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Sample records for geostatistical study evaluation

  1. Quick evaluation of multiple geostatistical models using upscaling with coarse grids: A practical study

    Energy Technology Data Exchange (ETDEWEB)

    Lemouzy, P. [Institut Francais du Petrole and ELF/IFP Helios Group, Pau (France)

    1997-08-01

    In field delineation phase, uncertainty in hydrocarbon reservoir descriptions is large. To quickly examine the impact of this uncertainty on production performance, it is necessary to evaluate a large number of descriptions in relation to possible production methods (well spacing, injection rate, etc.). The method of using coarse upscaled models was first proposed by Ballin. Unlike other methods (connectivity analysis, tracer simulations), it considers parameters such as PVT, well management, etc. After a detailed review of upscaling issues, applications to water-injection cases (either with balance or imbalance of production, with or without aquifer) and to depletion of an oil reservoir with aquifer coning are presented. Much more important than the method of permeability upscaling far from wells, the need of correct upscaling of numerical well representation is pointed out Methods are proposed to accurately represent fluids volumes in coarse models. Simple methods to upscale relative permeabilities, and methods to efficiently correct numerical dispersion are proposed. Good results are obtained for water injection. The coarse upscaling method allows the performance of sensitivity analyses on model parameters at a much lower CPU cost than comprehensive simulations. Models representing extreme behaviors can be easily distinguished. For depletion of an oil reservoir showing aquifer coning, however, the method did not work property. It is our opinion that further research is required for upscaling close to wells. We therefore recombined this method for practical use in the case of water injection.

  2. Study of the plywood panels properties using geostatistic

    Directory of Open Access Journals (Sweden)

    Cleverson Pinheiro

    2016-12-01

    Full Text Available Plywood panels have multiple applications in construction, in the furniture industry and packaging. There is a need to improve techniques for assessing quality of these products. This paper proposed the use of geostatistics to evaluate the behavior of the of the plywood panel. The physical properties were analyzed (moisture content, density and water absorption in the full extent of the plywood panel of Eucalyptus sp., bonded with adhesive single-component polyurethane. For analysis, three panels of five layers, with dimensions of 350 x 350 x 15.5 mm each, were employed. The tests were based on the standards EN 323-2000, EN 322-2000 and ABNT NBR 9486- 2011. Statistical modeling was performed using the R software, using the methodology of geostatistics. The average results were compared with values reported in the literature. The average water absorption was 7% higher in comparison with other studies, which used urea formaldehyde. So, the product can be applied only to interior and their use is not advisable for floors; the average moisture content and density were within the average values found in the literature. The behavior of the properties analyzed using the geostatistical model was not homogeneous, with large variations. Geostatistics was considered an appropriate tool for the study of the variability of the plywood panel properties, and can be applied for better quality control of them.

  3. Geostatistical evaluation of travel time uncertainties

    International Nuclear Information System (INIS)

    Devary, J.L.

    1983-08-01

    Data on potentiometric head and hydraulic conductivity, gathered from the Wolfcamp Formation of the Permian System, have exhibited tremendous spatial variability as a result of heterogeneities in the media and the presence of petroleum and natural gas deposits. Geostatistical data analysis and error propagation techniques (kriging and conditional simulation) were applied to determine the effect of potentiometric head uncertainties on radionuclide travel paths and travel times through the Wolfcamp Formation. Blok-average kriging was utilized to remove measurement error from potentiometric head data. The travel time calculations have been enhanced by the use of an inverse technique to determine the relative hydraulic conductivity along travel paths. In this way, the spatial variability of the hydraulic conductivity corresponding to streamline convergence and divergence may be included in the analysis. 22 references, 11 figures, 1 table

  4. Use of geostatistics on broiler production for evaluation of different minimum ventilation systems during brooding phase

    Directory of Open Access Journals (Sweden)

    Thayla Morandi Ridolfi de Carvalho

    2012-01-01

    Full Text Available The objective of this research was to evaluate different minimum ventilation systems, in relation to air quality and thermal comfort using geostatistics in brooding phase. The minimum ventilation systems were: Blue House I: exhaust fans + curtain management (end of the building; Blue House II: exhaust fans + side curtain management; and Dark House: exhaust fans + flag. The climate variables evaluated were: dry bulb temperature, relative humidity, air velocity, carbon dioxide and ammonia concentration, during winter time, at 9 a.m., in 80 equidistant points in brooding area. Data were evaluated by geostatistic technique. The results indicate that Wider broiler houses (above 15.0 m width present the greatest ammonia and humidity concentration. Blue House II present the best results in relation to air quality. However, none of the studied broiler houses present an ideal thermal comfort.

  5. Study on geological environment model using geostatistics method

    International Nuclear Information System (INIS)

    Honda, Makoto; Suzuki, Makoto; Sakurai, Hideyuki; Iwasa, Kengo; Matsui, Hiroya

    2005-03-01

    The purpose of this study is to develop the geostatistical procedure for modeling geological environments and to evaluate the quantitative relationship between the amount of information and the reliability of the model using the data sets obtained in the surface-based investigation phase (Phase 1) of the Horonobe Underground Research Laboratory Project. This study lasts for three years from FY2004 to FY2006 and this report includes the research in FY2005 as the second year of three-year study. In FY2005 research, the hydrogeological model was built as well as FY2004 research using the data obtained from the deep boreholes (HDB-6, 7 and 8) and the ground magnetotelluric (AMT) survey which were executed in FY2004 in addition to the data sets used in the first year of study. Above all, the relationship between the amount of information and the reliability of the model was demonstrated through a comparison of the models at each step which corresponds to the investigation stage in each FY. Furthermore, the statistical test was applied for detecting the difference of basic statistics of various data due to geological features with a view to taking the geological information into the modeling procedures. (author)

  6. Evaluation of geostatistical parameters based on well tests; Estimation de parametres geostatistiques a partir de tests de puits

    Energy Technology Data Exchange (ETDEWEB)

    Gauthier, Y.

    1997-10-20

    Geostatistical tools are increasingly used to model permeability fields in subsurface reservoirs, which are considered as a particular random variable development depending of several geostatistical parameters such as variance and correlation length. The first part of the thesis is devoted to the study of relations existing between the transient well pressure (the well test) and the stochastic permeability field, using the apparent permeability concept.The well test performs a moving permeability average over larger and larger volume with increasing time. In the second part, the geostatistical parameters are evaluated using well test data; a Bayesian framework is used and parameters are estimated using the maximum likelihood principle by maximizing the well test data probability density function with respect to these parameters. This method, involving a well test fast evaluation, provides an estimation of the correlation length and the variance over different realizations of a two-dimensional permeability field

  7. How to evaluate the risks of exceeding limits: geostatistical models and their application to air pollution

    International Nuclear Information System (INIS)

    Fouquet, Ch. de; Deraisme, J.; Bobbia, M.

    2007-01-01

    Geo-statistics is increasingly applied to the study of environmental risks in a variety of sectors, especially in the fields of soil decontamination and the evaluation of the risks due to air pollution. Geo-statistics offers a rigorous stochastic modeling approach that makes it possible to answer questions expressed in terms of uncertainty and risk. This article focusses on nonlinear geo-statistical methods, based on the Gaussian random function model, whose essential properties are summarised. We use two examples to characterize situations where direct and thus rapid methods provide appropriate solutions and cases that inevitably require more laborious simulation techniques. Exposure of the population of the Rouen metropolitan area to the risk of NO 2 pollution is assessed by simulations, but the surface area where the pollution exceeds the threshold limit can be easily estimated with nonlinear conditional expectation techniques. A second example is used to discuss the bias introduced by direct simulation, here of a percentile of daily SO 2 concentration for one year in the city of Le Havre; an operational solution is proposed. (authors)

  8. Characterization of groundwater quality using water evaluation indices, multivariate statistics and geostatistics in central Bangladesh

    Directory of Open Access Journals (Sweden)

    Md. Bodrud-Doza

    2016-04-01

    Full Text Available This study investigates the groundwater quality in the Faridpur district of central Bangladesh based on preselected 60 sample points. Water evaluation indices and a number of statistical approaches such as multivariate statistics and geostatistics are applied to characterize water quality, which is a major factor for controlling the groundwater quality in term of drinking purposes. The study reveal that EC, TDS, Ca2+, total As and Fe values of groundwater samples exceeded Bangladesh and international standards. Ground water quality index (GWQI exhibited that about 47% of the samples were belonging to good quality water for drinking purposes. The heavy metal pollution index (HPI, degree of contamination (Cd, heavy metal evaluation index (HEI reveal that most of the samples belong to low level of pollution. However, Cd provide better alternative than other indices. Principle component analysis (PCA suggests that groundwater quality is mainly related to geogenic (rock–water interaction and anthropogenic source (agrogenic and domestic sewage in the study area. Subsequently, the findings of cluster analysis (CA and correlation matrix (CM are also consistent with the PCA results. The spatial distributions of groundwater quality parameters are determined by geostatistical modeling. The exponential semivariagram model is validated as the best fitted models for most of the indices values. It is expected that outcomes of the study will provide insights for decision makers taking proper measures for groundwater quality management in central Bangladesh.

  9. Evaluation of statistical and geostatistical models of digital soil properties mapping in tropical mountain regions

    Directory of Open Access Journals (Sweden)

    Waldir de Carvalho Junior

    2014-06-01

    Full Text Available Soil properties have an enormous impact on economic and environmental aspects of agricultural production. Quantitative relationships between soil properties and the factors that influence their variability are the basis of digital soil mapping. The predictive models of soil properties evaluated in this work are statistical (multiple linear regression-MLR and geostatistical (ordinary kriging and co-kriging. The study was conducted in the municipality of Bom Jardim, RJ, using a soil database with 208 sampling points. Predictive models were evaluated for sand, silt and clay fractions, pH in water and organic carbon at six depths according to the specifications of the consortium of digital soil mapping at the global level (GlobalSoilMap. Continuous covariates and categorical predictors were used and their contributions to the model assessed. Only the environmental covariates elevation, aspect, stream power index (SPI, soil wetness index (SWI, normalized difference vegetation index (NDVI, and b3/b2 band ratio were significantly correlated with soil properties. The predictive models had a mean coefficient of determination of 0.21. Best results were obtained with the geostatistical predictive models, where the highest coefficient of determination 0.43 was associated with sand properties between 60 to 100 cm deep. The use of a sparse data set of soil properties for digital mapping can explain only part of the spatial variation of these properties. The results may be related to the sampling density and the quantity and quality of the environmental covariates and predictive models used.

  10. Geostatistical Study of Precipitation on the Island of Crete

    Science.gov (United States)

    Agou, Vasiliki D.; Varouchakis, Emmanouil A.; Hristopulos, Dionissios T.

    2015-04-01

    Understanding and predicting the spatiotemporal patterns of precipitation in the Mediterranean islands is an important topic of research, which is emphasized by alarming long-term predictions for increased drought conditions [4]. The analysis of records from drought-prone areas around the world has demonstrated that precipitation data are non-Gaussian. Typically, such data are fitted to the gamma distribution function and then transformed into a normalized index, the so-called Standardized Precipitation Index (SPI) [5]. The SPI can be defined for different time scales and has been applied to data from various regions [2]. Precipitation maps can be constructed using the stochastic method of Ordinary Kriging [1]. Such mathematical tools help to better understand the space-time variability and to plan water resources management. We present preliminary results of an ongoing investigation of the space-time precipitation distribution on the island of Crete (Greece). The study spans the time period from 1948 to 2012 and extends over an area of 8 336 km2. The data comprise monthly precipitation measured at 56 stations. Analysis of the data showed that the most severe drought occurred in 1950 followed by 1989, whereas the wettest year was 2002 followed by 1977. A spatial trend was observed with the spatially averaged annual precipitation in the West measured at about 450mm higher than in the East. Analysis of the data also revealed strong correlations between the precipitation in the western and eastern parts of the island. In addition to longitude, elevation (masl) was determined to be an important factor that exhibits strong linear correlation with precipitation. The precipitation data exhibit wet and dry periods with strong variability even during the wet period. Thus, fitting the data to specific probability distribution models has proved challenging. Different time scales, e.g. monthly, biannual, and annual have been investigated. Herein we focus on annual

  11. Comparative study of the geostatistical ore reserve estimation method over the conventional methods

    International Nuclear Information System (INIS)

    Kim, Y.C.; Knudsen, H.P.

    1975-01-01

    Part I contains a comprehensive treatment of the comparative study of the geostatistical ore reserve estimation method over the conventional methods. The conventional methods chosen for comparison were: (a) the polygon method, (b) the inverse of the distance squared method, and (c) a method similar to (b) but allowing different weights in different directions. Briefly, the overall result from this comparative study is in favor of the use of geostatistics in most cases because the method has lived up to its theoretical claims. A good exposition on the theory of geostatistics, the adopted study procedures, conclusions and recommended future research are given in Part I. Part II of this report contains the results of the second and the third study objectives, which are to assess the potential benefits that can be derived by the introduction of the geostatistical method to the current state-of-the-art in uranium reserve estimation method and to be instrumental in generating the acceptance of the new method by practitioners through illustrative examples, assuming its superiority and practicality. These are given in the form of illustrative examples on the use of geostatistics and the accompanying computer program user's guide

  12. Geostatistical methods for radiological evaluation and risk analysis of contaminated premises

    International Nuclear Information System (INIS)

    Desnoyers, Y.; Jeannee, N.; Chiles, J.P.; Dubot, D.

    2009-01-01

    Full text: At the end of process equipment dismantling, the complete decontamination of nuclear facilities requires the radiological assessment of residual activity levels of building structures. As stated by the IAEA, 'Segregation and characterization of contaminated materials are the key elements of waste minimization'. From this point of view, the set up of an appropriate evaluation methodology is of primordial importance. The radiological characterization of contaminated premises can be divided into three steps. First, the most exhaustive facility analysis provides historical, functional and qualitative information. Then, a systematic (exhaustive or not) control of the emergent signal is performed by means of in situ measurement methods such as surface control device combined with in situ gamma spectrometry. Besides, in order to assess the contamination depth, samples can be collected from boreholes at several locations within the premises and analyzed. Combined with historical information and emergent signal maps, such data improve and reinforce the preliminary waste zoning. In order to provide reliable estimates while avoiding supplementary investigation costs, there is therefore a crucial need for sampling optimization methods together with appropriate data processing techniques. The relevance of the geostatistical methodology relies on the presence of a spatial continuity for radiological contamination. In this case, geostatistics provides reliable methods for activity estimation, uncertainty quantification and risk analysis, which are essential decision-making tools for decommissioning and dismantling projects of nuclear installations. Besides, the ability of this geostatistical framework to provide answers to several key issues that generally occur during the clean-up preparation phase is discussed: How to optimise the investigation costs? How to deal with data quality issues? How to consistently take into account auxiliary information such as historical

  13. A conceptual sedimentological-geostatistical model of aquifer heterogeneity based on outcrop studies

    Energy Technology Data Exchange (ETDEWEB)

    Davis, J.M.

    1994-01-01

    Three outcrop studies were conducted in deposits of different depositional environments. At each site, permeability measurements were obtained with an air-minipermeameter developed as part of this study. In addition, the geological units were mapped with either surveying, photographs, or both. Geostatistical analysis of the permeability data was performed to estimate the characteristics of the probability distribution function and the spatial correlation structure. The information obtained from the geological mapping was then compared with the results of the geostatistical analysis for any relationships that may exist. The main field site was located in the Albuquerque Basin of central New Mexico at an outcrop of the Pliocene-Pleistocene Sierra Ladrones Formation. The second study was conducted on the walls of waste pits in alluvial fan deposits at the Nevada Test Site. The third study was conducted on an outcrop of an eolian deposit (miocene) south of Socorro, New Mexico. The results of the three studies were then used to construct a conceptual model relating depositional environment to geostatistical models of heterogeneity. The model presented is largely qualitative but provides a basis for further hypothesis formulation and testing.

  14. A conceptual sedimentological-geostatistical model of aquifer heterogeneity based on outcrop studies

    International Nuclear Information System (INIS)

    Davis, J.M.

    1994-01-01

    Three outcrop studies were conducted in deposits of different depositional environments. At each site, permeability measurements were obtained with an air-minipermeameter developed as part of this study. In addition, the geological units were mapped with either surveying, photographs, or both. Geostatistical analysis of the permeability data was performed to estimate the characteristics of the probability distribution function and the spatial correlation structure. The information obtained from the geological mapping was then compared with the results of the geostatistical analysis for any relationships that may exist. The main field site was located in the Albuquerque Basin of central New Mexico at an outcrop of the Pliocene-Pleistocene Sierra Ladrones Formation. The second study was conducted on the walls of waste pits in alluvial fan deposits at the Nevada Test Site. The third study was conducted on an outcrop of an eolian deposit (miocene) south of Socorro, New Mexico. The results of the three studies were then used to construct a conceptual model relating depositional environment to geostatistical models of heterogeneity. The model presented is largely qualitative but provides a basis for further hypothesis formulation and testing

  15. Geostatistical evaluation of integrated marsh management impact on mosquito vectors using before-after-control-impact (BACI design

    Directory of Open Access Journals (Sweden)

    Dempsey Mary E

    2009-06-01

    Full Text Available Abstract Background In many parts of the world, salt marshes play a key ecological role as the interface between the marine and the terrestrial environments. Salt marshes are also exceedingly important for public health as larval habitat for mosquitoes that are vectors of disease and significant biting pests. Although grid ditching and pesticides have been effective in salt marsh mosquito control, marsh degradation and other environmental considerations compel a different approach. Targeted habitat modification and biological control methods known as Open Marsh Water Management (OMWM had been proposed as a viable alternative to marsh-wide physical alterations and chemical control. However, traditional larval sampling techniques may not adequately assess the impacts of marsh management on mosquito larvae. To assess the effectiveness of integrated OMWM and marsh restoration techniques for mosquito control, we analyzed the results of a 5-year OMWM/marsh restoration project to determine changes in mosquito larval production using GIS and geostatistical methods. Methods The following parameters were evaluated using "Before-After-Control-Impact" (BACI design: frequency and geographic extent of larval production, intensity of larval production, changes in larval habitat, and number of larvicide applications. The analyses were performed using Moran's I, Getis-Ord, and Spatial Scan statistics on aggregated before and after data as well as data collected over time. This allowed comparison of control and treatment areas to identify changes attributable to the OMWM/marsh restoration modifications. Results The frequency of finding mosquito larvae in the treatment areas was reduced by 70% resulting in a loss of spatial larval clusters compared to those found in the control areas. This effect was observed directly following OMWM treatment and remained significant throughout the study period. The greatly reduced frequency of finding larvae in the treatment

  16. Geostatistical evaluation of integrated marsh management impact on mosquito vectors using before-after-control-impact (BACI) design.

    Science.gov (United States)

    Rochlin, Ilia; Iwanejko, Tom; Dempsey, Mary E; Ninivaggi, Dominick V

    2009-06-23

    In many parts of the world, salt marshes play a key ecological role as the interface between the marine and the terrestrial environments. Salt marshes are also exceedingly important for public health as larval habitat for mosquitoes that are vectors of disease and significant biting pests. Although grid ditching and pesticides have been effective in salt marsh mosquito control, marsh degradation and other environmental considerations compel a different approach. Targeted habitat modification and biological control methods known as Open Marsh Water Management (OMWM) had been proposed as a viable alternative to marsh-wide physical alterations and chemical control. However, traditional larval sampling techniques may not adequately assess the impacts of marsh management on mosquito larvae. To assess the effectiveness of integrated OMWM and marsh restoration techniques for mosquito control, we analyzed the results of a 5-year OMWM/marsh restoration project to determine changes in mosquito larval production using GIS and geostatistical methods. The following parameters were evaluated using "Before-After-Control-Impact" (BACI) design: frequency and geographic extent of larval production, intensity of larval production, changes in larval habitat, and number of larvicide applications. The analyses were performed using Moran's I, Getis-Ord, and Spatial Scan statistics on aggregated before and after data as well as data collected over time. This allowed comparison of control and treatment areas to identify changes attributable to the OMWM/marsh restoration modifications. The frequency of finding mosquito larvae in the treatment areas was reduced by 70% resulting in a loss of spatial larval clusters compared to those found in the control areas. This effect was observed directly following OMWM treatment and remained significant throughout the study period. The greatly reduced frequency of finding larvae in the treatment areas led to a significant decrease (approximately 44%) in

  17. A geostatistical analysis of geostatistics

    NARCIS (Netherlands)

    Hengl, T.; Minasny, B.; Gould, M.

    2009-01-01

    The bibliometric indices of the scientific field of geostatistics were analyzed using statistical and spatial data analysis. The publications and their citation statistics were obtained from the Web of Science (4000 most relevant), Scopus (2000 most relevant) and Google Scholar (5389). The focus was

  18. Application of Bayesian geostatistics for evaluation of mass discharge uncertainty at contaminated sites

    DEFF Research Database (Denmark)

    Troldborg, Mads; Nowak, Wolfgang; Lange, Ida Vedel

    2012-01-01

    , and (3) uncertain source zone and transport parameters. The method generates conditional realizations of the spatial flow and concentration distribution. An analytical macrodispersive transport solution is employed to simulate the mean concentration distribution, and a geostatistical model of the Box......Mass discharge estimates are increasingly being used when assessing risks of groundwater contamination and designing remedial systems at contaminated sites. Such estimates are, however, rather uncertain as they integrate uncertain spatial distributions of both concentration and groundwater flow....... Here a geostatistical simulation method for quantifying the uncertainty of the mass discharge across a multilevel control plane is presented. The method accounts for (1) heterogeneity of both the flow field and the concentration distribution through Bayesian geostatistics, (2) measurement uncertainty...

  19. A geostatistical method applied to the geochemical study of the Chichinautzin Volcanic Field in Mexico

    Science.gov (United States)

    Robidoux, P.; Roberge, J.; Urbina Oviedo, C. A.

    2011-12-01

    The origin of magmatism and the role of the subducted Coco's Plate in the Chichinautzin volcanic field (CVF), Mexico is still a subject of debate. It has been established that mafic magmas of alkali type (subduction) and calc-alkali type (OIB) are produced in the CVF and both groups cannot be related by simple fractional crystallization. Therefore, many geochemical studies have been done, and many models have been proposed. The main goal of the work present here is to provide a new tool for the visualization and interpretation of geochemical data using geostatistics and geospatial analysis techniques. It contains a complete geodatabase built from referred samples over the 2500 km2 area of CVF and its neighbour stratovolcanoes (Popocatepetl, Iztaccihuatl and Nevado de Toluca). From this database, map of different geochemical markers were done to visualise geochemical signature in a geographical manner, to test the statistic distribution with a cartographic technique and highlight any spatial correlations. The distribution and regionalization of the geochemical signatures can be viewed in a two-dimensional space using a specific spatial analysis tools from a Geographic Information System (GIS). The model of spatial distribution is tested with Linear Decrease (LD) and Inverse Distance Weight (IDW) interpolation technique because they best represent the geostatistical characteristics of the geodatabase. We found that ratio of Ba/Nb, Nb/Ta, Th/Nb show first order tendency, which means visible spatial variation over a large scale area. Monogenetic volcanoes in the center of the CVF have distinct values compare to those of the Popocatepetl-Iztaccihuatl polygenetic complex which are spatially well defined. Inside the Valley of Mexico, a large quantity of monogenetic cone in the eastern portion of CVF has ratios similar to the Iztaccihuatl and Popocatepetl complex. Other ratios like alkalis vs SiO2, V/Ti, La/Yb, Zr/Y show different spatial tendencies. In that case, second

  20. A geostatistical study of the uranium deposit at Kvanefjeld, the Ilimaussaq intrusion, South Greenland

    International Nuclear Information System (INIS)

    Lund Clausen, F.

    1982-05-01

    The uranium deposit at Kvanefjeld within the Ilimaussaq intrusion in South Greenland has been tested by diamond drilling, hole logging, chip sampling and field gamma-spectrometric surveys. Based on these different types of spatially distributed samples the uranium variation within the deposit was studied. The spatial variation, which comprises a large random component, was modelled, and the intrinsic function was used to establish gradetonnage curves by the best linear unbiased estimator of geostatistics (kriging). From data obtained by a ground surface gamma-spectrometric survey it is shown that the uranium variation is possibly subject to a spatial anisotropy consistent with the geology. The uranium variation has a second-order stationarity. A global estimation of the total reserves shows that single block grade values are always estimated with high errors. This is mainly caused by the poor spatial structure and the very sparse sampling pattern. The best way to solve this problem appears to be a selective type of kriging. The overall uranium reserves are estimated as 23600 tons with a mean grade of 297 ppm (cutoff grade 250 ppm U). Studies of data from a test adit show that local geostatistical estimation can be done with acceptably small errors provided that a close sampling pattern is used. A regression relationship is established to correct field gamma-spectrometric measures of bulk grades towards truer values. Multivariate cluster and discriminant analyses were used to classify lujavrite samples based on their trace element content. Misclassification is due to a possibly continuous transition between naujakasite lujavrite and arfvedsonite lujavrite. Some of the main mineralogical differences between the geological units are identified by the discriminating effect of the individual variable. (author)

  1. Evaluation of spatial variability of metal bioavailability in soils using geostatistics

    DEFF Research Database (Denmark)

    Owsianiak, Mikolaj; Hauschild, Michael Zwicky; Rosenbaum, Ralph K.

    2012-01-01

    Soil properties show signifficant spatial variability at local, regional and continental scales. This is a challenge for life cycle impact assessment (LCIA) of metals, because fate, bioavailability and effect factors are controlled by environmental chemistry and can vary orders of magnitude...... for different soils. Here, variography is employed to analyse spatial variability of bioavailability factors (BFs) of metals at the global scale. First, published empirical regressions are employed to calculate BFs of metals for 7180 topsoil profiles. Next, geostatistical interpretation of calculated BFs...... is performed using ArcGIS Geostatistical Analyst. Results show that BFs of copper span a range of 6 orders of magnitude, and have signifficant spatial variability at local and continental scales. The model nugget variance is signifficantly higher than zero, suggesting the presence of spatial variability...

  2. A Bayesian geostatistical approach for evaluating the uncertainty of contaminant mass discharges from point sources

    DEFF Research Database (Denmark)

    Troldborg, Mads; Nowak, Wolfgang; Binning, Philip John

    of both concentration and groundwater flow. For risk assessments or any other decisions that are being based on mass discharge estimates, it is essential to address these uncertainties. We present a novel Bayesian geostatistical approach for quantifying the uncertainty of the mass discharge across...... and the hydraulic gradient across the control plane and are consistent with measurements of both hydraulic conductivity and head at the site. An analytical macro-dispersive transport solution is employed to simulate the mean concentration distribution across the control plane, and a geostatistical model of the Box......Estimates of mass discharge (mass/time) are increasingly being used when assessing risks of groundwater contamination and designing remedial systems at contaminated sites. Mass discharge estimates are, however, prone to rather large uncertainties as they integrate uncertain spatial distributions...

  3. Dose rate estimates and spatial interpolation maps of outdoor gamma dose rate with geostatistical methods; A case study from Artvin, Turkey

    International Nuclear Information System (INIS)

    Yeşilkanat, Cafer Mert; Kobya, Yaşar; Taşkin, Halim; Çevik, Uğur

    2015-01-01

    In this study, compliance of geostatistical estimation methods is compared to ensure investigation and imaging natural Fon radiation using the minimum number of data. Artvin province, which has a quite hilly terrain and wide variety of soil and located in the north–east of Turkey, is selected as the study area. Outdoor gamma dose rate (OGDR), which is an important determinant of environmental radioactivity level, is measured in 204 stations. Spatial structure of OGDR is determined by anisotropic, isotropic and residual variograms. Ordinary kriging (OK) and universal kriging (UK) interpolation estimations were calculated with the help of model parameters obtained from these variograms. In OK, although calculations are made based on positions of points where samples are taken, in the UK technique, general soil groups and altitude values directly affecting OGDR are included in the calculations. When two methods are evaluated based on their performances, it has been determined that UK model (r = 0.88, p < 0.001) gives quite better results than OK model (r = 0.64, p < 0.001). In addition, as a result of the maps created at the end of the study, it was illustrated that local changes are better reflected by UK method compared to OK method and its error variance is found to be lower. - Highlights: • The spatial dispersion of gamma dose rates in Artvin, which possesses one of the roughest lands in Turkey were studied. • The performance of different Geostatistic methods (OK and UK methods) for dispersion of gamma dose rates were compared. • Estimation values were calculated for non-sampling points by using the geostatistical model, the results were mapped. • The general radiological structure was determined in much less time with lower costs compared to experimental methods. • When theoretical methods are evaluated, it was obtained that UK gives more descriptive results compared to OK.

  4. Geostatistics as a tool to study mite dispersion in physic nut plantations.

    Science.gov (United States)

    Rosado, J F; Picanço, M C; Sarmento, R A; Pereira, R M; Pedro-Neto, M; Galdino, T V S; de Sousa Saraiva, A; Erasmo, E A L

    2015-08-01

    Spatial distribution studies in pest management identify the locations where pest attacks on crops are most severe, enabling us to understand and predict the movement of such pests. Studies on the spatial distribution of two mite species, however, are rather scarce. The mites Polyphagotarsonemus latus and Tetranychus bastosi are the major pests affecting physic nut plantations (Jatropha curcas). Therefore, the objective of this study was to measure the spatial distributions of P. latus and T. bastosi in the physic nut plantations. Mite densities were monitored over 2 years in two different plantations. Sample locations were georeferenced. The experimental data were analyzed using geostatistical analyses. The total mite density was found to be higher when only one species was present (T. bastosi). When both the mite species were found in the same plantation, their peak densities occurred at different times. These mites, however, exhibited uniform spatial distribution when found at extreme densities (low or high). However, the mites showed an aggregated distribution in intermediate densities. Mite spatial distribution models were isotropic. Mite colonization commenced at the periphery of the areas under study, whereas the high-density patches extended until they reached 30 m in diameter. This has not been reported for J. curcas plants before.

  5. Geostatistical Evaluation of Spring Water Quality in an Urbanizing Carbonate Aquifer

    Science.gov (United States)

    McGinty, A.; Welty, C.

    2003-04-01

    As part of an investigation of the impacts of urbanization on the hydrology and ecology of Valley Creek watershed near Philadelphia, Pennsylvania, we have analyzed the chemical composition of 110 springs to assess the relative influence of geology and anthropogenic activities on water quality. The 60 km^2 watershed is underlain by productive fractured rock aquifers composed of Cambrian and Ordovician carbonate rocks in the central valley and Cambrian crystalline and siliciclastic rocks (quartzite and phyllite) in the north and south hills that border the valley. All tributaries of the surface water system originate in the crystalline and siliciclastic hills. The watershed is covered by 17% impervious area and contains 6 major hazardous waste sites, one active quarrying operation and one golf course; 25% of the area utilizes septic systems for sewage disposal. We identified 172 springs, 110 of which had measurable flow rates ranging from 0.002 to 5 l/s. The mapped surficial geology appears as an anisotropic pattern, with long bands of rock formations paralleling the geographic orientation of the valley. Mapped development appears as a more isotropic pattern, characterized by isolated patches of land use that are not coincident with the evident geologic pattern. Superimposed upon these characteristics is a dense array of depressions and shallow sinkholes in the carbonate rocks, and a system of major faults at several formation contacts. We used indicator geostatistics to quantitatively characterize the spatial extent of the major geologic formations and patterns of land use. Maximum correlation scales for the rock types corresponded with strike direction and ranged from 1000 to 3000 m. Anisotropy ratios ranged from 2 to 4. Land-use correlation scales were generally smaller (200 to 500 m) with anisotropy ratios of around 1.2, i.e., nearly isotropic as predicted. Geostatistical analysis of spring water quality parameters related to geology (pH, specific conductance

  6. Survey and Zoning of Soil Physical and Chemical Properties Using Geostatistical Methods in GIS (Case Study: Miankangi Region in Sistan

    Directory of Open Access Journals (Sweden)

    M. Hashemi

    2017-02-01

    Full Text Available Introduction: In order to provide a database, it is essential having access to accurate information on soil spatial variation for soil sustainable management such as proper application of fertilizers. Spatial variations in soil properties are common but it is important for understanding these changes, particularly in agricultural lands for careful planning and land management. Materials and Methods: To this end, in winter 1391, 189 undisturbed soil samples (0-30 cm depth in a regular lattice with a spacing of 500 m were gathered from the surface of Miankangi land, Sistan plain, and their physical and chemical properties were studied. The land area of the region is about 4,500 hectares; the average elevation of studied area is 489.2 meters above sea level with different land uses. Soil texture was measured by the hydrometer methods (11, Also EC and pH (39, calcium carbonate equivalent (37 and the saturation percentage of soils were determined. Kriging, Co-Kriging, Inverse Distance Weighting and Local Polynomial Interpolation techniques were evaluated to produce a soil characteristics map of the study area zoning and to select the best geostatistical methods. Cross-validation techniques and Root Mean Square Error (RMSE were used. Results and Discussion: Normalized test results showed that all of the soil properties except calcium carbonate and soil clay content had normal distribution. In addition, the results of correlation test showed that the soil saturation percentage was positively correlated with silt content (r=0.43 and p

  7. Epidemiological study of hazelnut bacterial blight in central Italy by using laboratory analysis and geostatistics.

    Directory of Open Access Journals (Sweden)

    Jay Ram Lamichhane

    Full Text Available Incidence of Xanthomonas arboricola pv. corylina, the causal agent of hazelnut bacterial blight, was analyzed spatially in relation to the pedoclimatic factors. Hazelnut grown in twelve municipalities situated in the province of Viterbo, central Italy was studied. A consistent number of bacterial isolates were obtained from the infected tissues of hazelnut collected in three years (2010-2012. The isolates, characterized by phenotypic tests, did not show any difference among them. Spatial patterns of pedoclimatic data, analyzed by geostatistics showed a strong positive correlation of disease incidence with higher values of rainfall, thermal shock and soil nitrogen; a weak positive correlation with soil aluminium content and a strong negative correlation with the values of Mg/K ratio. No correlation of the disease incidence was found with soil pH. Disease incidence ranged from very low (<1% to very high (almost 75% across the orchards. Young plants (4-year old were the most affected by the disease confirming a weak negative correlation of the disease incidence with plant age. Plant cultivars did not show any difference in susceptibility to the pathogen. Possible role of climate change on the epidemiology of the disease is discussed. Improved management practices are recommended for effective control of the disease.

  8. Space-time geostatistics for geography: a case study of radiation monitoring across parts of Germany

    NARCIS (Netherlands)

    Heuvelink, G.B.M.; Griffith, D.A.

    2010-01-01

    Many branches within geography deal with variables that vary not only in space but also in time. Therefore, conventional geostatistics needs to be extended with methods that estimate and quantify spatiotemporal variation and use it in spatiotemporal interpolation and stochastic simulation. This

  9. Geostatistical and Stochastic Study of Flow and Tracer Transport in the Unsaturated Zone at Yucca Mountain

    International Nuclear Information System (INIS)

    Ye, Ming; Pan, Feng; Hu, Xiaolong; Zhu, Jianting

    2007-01-01

    Yucca Mountain has been proposed by the U.S. Department of Energy as the nation's long-term, permanent geologic repository for spent nuclear fuel or high-level radioactive waste. The potential repository would be located in Yucca Mountain's unsaturated zone (UZ), which acts as a critical natural barrier delaying arrival of radionuclides to the water table. Since radionuclide transport in groundwater can pose serious threats to human health and the environment, it is important to understand how much and how fast water and radionuclides travel through the UZ to groundwater. The UZ system consists of multiple hydrogeologic units whose hydraulic and geochemical properties exhibit systematic and random spatial variation, or heterogeneity, at multiple scales. Predictions of radionuclide transport under such complicated conditions are uncertain, and the uncertainty complicates decision making and risk analysis. This project aims at using geostatistical and stochastic methods to assess uncertainty of unsaturated flow and radionuclide transport in the UZ at Yucca Mountain. Focus of this study is parameter uncertainty of hydraulic and transport properties of the UZ. The parametric uncertainty arises since limited parameter measurements are unable to deterministically describe spatial variability of the parameters. In this project, matrix porosity, permeability and sorption coefficient of the reactive tracer (neptunium) of the UZ are treated as random variables. Corresponding propagation of parametric uncertainty is quantitatively measured using mean, variance, 5th and 95th percentiles of simulated state variables (e.g., saturation, capillary pressure, percolation flux, and travel time). These statistics are evaluated using a Monte Carlo method, in which a three-dimensional flow and transport model implemented using the TOUGH2 code is executed with multiple parameter realizations of the random model parameters. The project specifically studies uncertainty of unsaturated flow

  10. Application of Geostatistical Modelling to Study the Exploration Adequacy of Uniaxial Compressive Strength of Intact Rock alongthe Behesht-Abad Tunnel Route

    Directory of Open Access Journals (Sweden)

    Mohammad Doustmohammadi

    2014-12-01

    Full Text Available Uniaxial compressive strength (UCS is one of the most significant factors on the stability of underground excavation projects. Most of the time, this factor can be obtained by exploratory boreholes evaluation. Due to the large distance between exploratory boreholes in the majority of geotechnical projects, the application of geostatistical methods has increased as an estimator of rock mass properties. The present paper ties the estimation of UCS values of intact rock to the distance between boreholes of the Behesht-Abad tunnel in central Iran, using SGEMS geostatistical program. Variography showed that UCS estimation of intact rock using geostatistical methods is reasonable. The model establishment and validation was done after assessment that the model was trustworthy. Cross validation proved the high accuracy (98% and reliability of the model to estimate uniaxial compressive strength. The UCS values were then estimated along the tunnel axis. Moreover, using geostatistical estimation led to better identification of the pros and cons of geotechnical explorations in each location of tunnel route.

  11. Geostatistics project of the National Uranium Resource Evaluation Program. Progress report, April-September 1980

    International Nuclear Information System (INIS)

    Johnson, M.E.; Howell, J.A.; Jackson, C.K.; Patterson, D.; Beckman, R.J.; Campbell, K.; Bement, T.R.

    1981-03-01

    A large computer code was written to perform a number of discriminant analysis procedures on aerial radiometric data. Work on percentile estimation, using the normal and log-normal probability distributions, was extended. Additional work was performed on methods of computing with large data sets. Attempts are being made to evaluate the behavior of principal components analysis relative to element distribution in a survey area. We also provided general statistical consulting in such areas as discriminant analysis, filtering, and kriging

  12. Geostatistical uncertainty of assessing air quality using high-spatial-resolution lichen data: A health study in the urban area of Sines, Portugal.

    Science.gov (United States)

    Ribeiro, Manuel C; Pinho, P; Branquinho, C; Llop, Esteve; Pereira, Maria J

    2016-08-15

    In most studies correlating health outcomes with air pollution, personal exposure assignments are based on measurements collected at air-quality monitoring stations not coinciding with health data locations. In such cases, interpolators are needed to predict air quality in unsampled locations and to assign personal exposures. Moreover, a measure of the spatial uncertainty of exposures should be incorporated, especially in urban areas where concentrations vary at short distances due to changes in land use and pollution intensity. These studies are limited by the lack of literature comparing exposure uncertainty derived from distinct spatial interpolators. Here, we addressed these issues with two interpolation methods: regression Kriging (RK) and ordinary Kriging (OK). These methods were used to generate air-quality simulations with a geostatistical algorithm. For each method, the geostatistical uncertainty was drawn from generalized linear model (GLM) analysis. We analyzed the association between air quality and birth weight. Personal health data (n=227) and exposure data were collected in Sines (Portugal) during 2007-2010. Because air-quality monitoring stations in the city do not offer high-spatial-resolution measurements (n=1), we used lichen data as an ecological indicator of air quality (n=83). We found no significant difference in the fit of GLMs with any of the geostatistical methods. With RK, however, the models tended to fit better more often and worse less often. Moreover, the geostatistical uncertainty results showed a marginally higher mean and precision with RK. Combined with lichen data and land-use data of high spatial resolution, RK is a more effective geostatistical method for relating health outcomes with air quality in urban areas. This is particularly important in small cities, which generally do not have expensive air-quality monitoring stations with high spatial resolution. Further, alternative ways of linking human activities with their

  13. Geostatistical methods in evaluating spatial variability of groundwater quality in Al-Kharj Region, Saudi Arabia

    Science.gov (United States)

    Al-Omran, Abdulrasoul M.; Aly, Anwar A.; Al-Wabel, Mohammad I.; Al-Shayaa, Mohammad S.; Sallam, Abdulazeam S.; Nadeem, Mahmoud E.

    2017-11-01

    The analyses of 180 groundwater samples of Al-Kharj, Saudi Arabia, recorded that most groundwaters are unsuitable for drinking uses due to high salinity; however, they can be used for irrigation with some restriction. The electric conductivity of studied groundwater ranged between 1.05 and 10.15 dS m-1 with an average of 3.0 dS m-1. Nitrate was also found in high concentration in some groundwater. Piper diagrams revealed that the majority of water samples are magnesium-calcium/sulfate-chloride water type. The Gibbs's diagram revealed that the chemical weathering of rock-forming minerals and evaporation are influencing the groundwater chemistry. A kriging method was used for predicting spatial distribution of salinity (EC dS m-1) and NO3 - (mg L-1) in Al-Kharj's groundwater using data of 180 different locations. After normalization of data, variogram was drawn, for selecting suitable model for fitness on experimental variogram, less residual sum of squares value was used. Then cross-validation and root mean square error were used to select the best method for interpolation. The kriging method was found suitable methods for groundwater interpolation and management using either GS+ or ArcGIS.

  14. Evaluating the effect of sampling and spatial correlation on ground-water travel time uncertainty coupling geostatistical, stochastic, and first order, second moment methods

    International Nuclear Information System (INIS)

    Andrews, R.W.; LaVenue, A.M.; McNeish, J.A.

    1989-01-01

    Ground-water travel time predictions at potential high-level waste repositories are subject to a degree of uncertainty due to the scale of averaging incorporated in conceptual models of the ground-water flow regime as well as the lack of data on the spatial variability of the hydrogeologic parameters. The present study describes the effect of limited observations of a spatially correlated permeability field on the predicted ground-water travel time uncertainty. Varying permeability correlation lengths have been used to investigate the importance of this geostatistical property on the tails of the travel time distribution. This study uses both geostatistical and differential analysis techniques. Following the generation of a spatially correlated permeability field which is considered reality, semivariogram analyses are performed upon small random subsets of the generated field to determine the geostatistical properties of the field represented by the observations. Kriging is then employed to generate a kriged permeability field and the corresponding standard deviation of the estimated field conditioned by the limited observations. Using both the real and kriged fields, the ground-water flow regime is simulated and ground-water travel paths and travel times are determined for various starting points. These results are used to define the ground-water travel time uncertainty due to path variability. The variance of the ground-water travel time along particular paths due to the variance of the permeability field estimated using kriging is then calculated using the first order, second moment method. The uncertainties in predicted travel time due to path and parameter uncertainties are then combined into a single distribution

  15. Regional-scale geostatistical inverse modeling of North American CO2 fluxes: a synthetic data study

    Directory of Open Access Journals (Sweden)

    A. M. Michalak

    2010-07-01

    Full Text Available A series of synthetic data experiments is performed to investigate the ability of a regional atmospheric inversion to estimate grid-scale CO2 fluxes during the growing season over North America. The inversions are performed within a geostatistical framework without the use of any prior flux estimates or auxiliary variables, in order to focus on the atmospheric constraint provided by the nine towers collecting continuous, calibrated CO2 measurements in 2004. Using synthetic measurements and their associated concentration footprints, flux and model-data mismatch covariance parameters are first optimized, and then fluxes and their uncertainties are estimated at three different temporal resolutions. These temporal resolutions, which include a four-day average, a four-day-average diurnal cycle with 3-hourly increments, and 3-hourly fluxes, are chosen to help assess the impact of temporal aggregation errors on the estimated fluxes and covariance parameters. Estimating fluxes at a temporal resolution that can adjust the diurnal variability is found to be critical both for recovering covariance parameters directly from the atmospheric data, and for inferring accurate ecoregion-scale fluxes. Accounting for both spatial and temporal a priori covariance in the flux distribution is also found to be necessary for recovering accurate a posteriori uncertainty bounds on the estimated fluxes. Overall, the results suggest that even a fairly sparse network of 9 towers collecting continuous CO2 measurements across the continent, used with no auxiliary information or prior estimates of the flux distribution in time or space, can be used to infer relatively accurate monthly ecoregion scale CO2 surface fluxes over North America within estimated uncertainty bounds. Simulated random transport error is shown to decrease the quality of flux estimates in under-constrained areas at the ecoregion scale, although the uncertainty bounds remain realistic. While these synthetic

  16. Geostatistics and Geographic Information Systems to Study the Spatial Distribution of Grapholita molesta (Busck) (Lepidoptera: Tortricidae) in Peach Fields.

    Science.gov (United States)

    Duarte, F; Calvo, M V; Borges, A; Scatoni, I B

    2015-08-01

    The oriental fruit moth, Grapholita molesta (Busck), is the most serious pest in peach, and several insecticide applications are required to reduce crop damage to acceptable levels. Geostatistics and Geographic Information Systems (GIS) are employed to measure the range of spatial correlation of G. molesta in order to define the optimum sampling distance for performing spatial analysis and to determine the current distribution of the pest in peach orchards of southern Uruguay. From 2007 to 2010, 135 pheromone traps per season were installed and georeferenced in peach orchards distributed over 50,000 ha. Male adult captures were recorded weekly from September to April. Structural analysis of the captures was performed, yielding 14 semivariograms for the accumulated captures analyzed by generation and growing season. Two sets of maps were constructed to describe the pest distribution. Nine significant models were obtained in the 14 evaluated periods. The range estimated for the correlation was from 908 to 6884 m. Three hot spots of high population level and some areas with comparatively low populations were constant over the 3-year period, while there is a greater variation in the size of the population in different generations and years in other areas.

  17. [Multivariate geostatistics and GIS-based approach to study the spatial distribution and sources of heavy metals in agricultural soil in the Pearl River Delta, China].

    Science.gov (United States)

    Cai, Li-mei; Ma, Jin; Zhou, Yong-zhang; Huang, Lan-chun; Dou, Lei; Zhang, Cheng-bo; Fu, Shan-ming

    2008-12-01

    One hundred and eighteen surface soil samples were collected from the Dongguan City, and analyzed for concentration of Cu, Zn, Ni, Cr, Pb, Cd, As, Hg, pH and OM. The spatial distribution and sources of soil heavy metals were studied using multivariate geostatistical methods and GIS technique. The results indicated concentrations of Cu, Zn, Ni, Pb, Cd and Hg were beyond the soil background content in Guangdong province, and especially concentrations of Pb, Cd and Hg were greatly beyond the content. The results of factor analysis group Cu, Zn, Ni, Cr and As in Factor 1, Pb and Hg in Factor 2 and Cd in Factor 3. The spatial maps based on geostatistical analysis show definite association of Factor 1 with the soil parent material, Factor 2 was mainly affected by industries. The spatial distribution of Factor 3 was attributed to anthropogenic influence.

  18. Geostatistical Three-Dimensional Modeling of a Tight Gas Reservoir: A Case Study of Block S6 of the Sulige Gas Field, Ordos Basin, China

    Directory of Open Access Journals (Sweden)

    Jinliang Zhang

    2017-09-01

    Full Text Available In this study, three-dimensional (3-D geostatistical models were constructed to quantify distributions of sandstone and mudstone. We propose a new method that employs weight coefficients to balance the sandstone and mudstone data from irregular well patterns during stochastic modeling. This new method begins with classifying well groups according to well distribution patterns; areas with similar well distribution patterns are classified within the same zone. Then, the distributions of sandstone and mudstone for each zone are simulated separately using the sequential indicator simulation (SIS method, and the relevant variogram parameters for each zone are computed. In this paper, we used block S6 of the Sulige Gas Field in Ordos Basin in China as a case study. We evaluated the quality of each set of parameters through the vacuation checking method; certain wells were removed to generate equiprobable realizations using different seed numbers. Subsequently, the variogram parameters for the entire S6 area were obtained by assigning different weight coefficients to the parameters of each zone. Finally, a quality assessment of the sandstone and mudstone models of the S6 area was conducted using the horizontal wells, which were not involved in the stochastic modeling process. The results show that these variogram parameters, which were calculated using weight coefficients, are reliable.

  19. Systematic evaluation of sequential geostatistical resampling within MCMC for posterior sampling of near-surface geophysical inverse problems

    Science.gov (United States)

    Ruggeri, Paolo; Irving, James; Holliger, Klaus

    2015-08-01

    We critically examine the performance of sequential geostatistical resampling (SGR) as a model proposal mechanism for Bayesian Markov-chain-Monte-Carlo (MCMC) solutions to near-surface geophysical inverse problems. Focusing on a series of simple yet realistic synthetic crosshole georadar tomographic examples characterized by different numbers of data, levels of data error and degrees of model parameter spatial correlation, we investigate the efficiency of three different resampling strategies with regard to their ability to generate statistically independent realizations from the Bayesian posterior distribution. Quite importantly, our results show that, no matter what resampling strategy is employed, many of the examined test cases require an unreasonably high number of forward model runs to produce independent posterior samples, meaning that the SGR approach as currently implemented will not be computationally feasible for a wide range of problems. Although use of a novel gradual-deformation-based proposal method can help to alleviate these issues, it does not offer a full solution. Further, we find that the nature of the SGR is found to strongly influence MCMC performance; however no clear rule exists as to what set of inversion parameters and/or overall proposal acceptance rate will allow for the most efficient implementation. We conclude that although the SGR methodology is highly attractive as it allows for the consideration of complex geostatistical priors as well as conditioning to hard and soft data, further developments are necessary in the context of novel or hybrid MCMC approaches for it to be considered generally suitable for near-surface geophysical inversions.

  20. Bayesian Geostatistical Design

    DEFF Research Database (Denmark)

    Diggle, Peter; Lophaven, Søren Nymand

    2006-01-01

    This paper describes the use of model-based geostatistics for choosing the set of sampling locations, collectively called the design, to be used in a geostatistical analysis. Two types of design situation are considered. These are retrospective design, which concerns the addition of sampling...... locations to, or deletion of locations from, an existing design, and prospective design, which consists of choosing positions for a new set of sampling locations. We propose a Bayesian design criterion which focuses on the goal of efficient spatial prediction whilst allowing for the fact that model...... parameter values are unknown. The results show that in this situation a wide range of interpoint distances should be included in the design, and the widely used regular design is often not the best choice....

  1. 10th International Geostatistics Congress

    CERN Document Server

    Rodrigo-Ilarri, Javier; Rodrigo-Clavero, María; Cassiraga, Eduardo; Vargas-Guzmán, José

    2017-01-01

    This book contains selected contributions presented at the 10th International Geostatistics Congress held in Valencia from 5 to 9 September, 2016. This is a quadrennial congress that serves as the meeting point for any engineer, professional, practitioner or scientist working in geostatistics. The book contains carefully reviewed papers on geostatistical theory and applications in fields such as mining engineering, petroleum engineering, environmental science, hydrology, ecology, and other fields.

  2. Geostatistical methodology for waste optimization of contaminated premises - 59344

    International Nuclear Information System (INIS)

    Desnoyers, Yvon; Dubot, Didier

    2012-01-01

    The presented methodological study illustrates a Geo-statistical approach suitable for radiological evaluation in nuclear premises. The waste characterization is mainly focused on floor concrete surfaces. By modeling the spatial continuity of activities, Geo-statistics provide sound methods to estimate and map radiological activities, together with their uncertainty. The multivariate approach allows the integration of numerous surface radiation measurements in order to improve the estimation of activity levels from concrete samples. This way, a sequential and iterative investigation strategy proves to be relevant to fulfill the different evaluation objectives. Waste characterization is performed on risk maps rather than on direct interpolation maps (due to bias of the selection on kriging results). The use of several estimation supports (punctual, 1 m 2 , room) allows a relevant radiological waste categorization thanks to cost-benefit analysis according to the risk of exceeding a given activity threshold. Global results, mainly total activity, are similarly quantified to precociously lead the waste management for the dismantling and decommissioning project. This paper recalled the geo-statistics principles and demonstrated how this methodology provides innovative tools for the radiological evaluation of contaminated premises. The relevance of this approach relies on the presence of a spatial continuity for radiological contamination. In this case, geo-statistics provides reliable activity estimates, uncertainty quantification and risk analysis, which are essential decision-making tools for decommissioning and dismantling projects of nuclear installations. Waste characterization is then performed taking all relevant information into account: historical knowledge, surface measurements and samples. Thanks to the multivariate processing, the different investigation stages can be rationalized as regards quantity and positioning. Waste characterization is finally

  3. Evaluation of Contaminations and Sources of Heavy Metals in Sediments at Samrak Delta of Nakdong River in Busan, Korea Using Geostatistical Methods

    Science.gov (United States)

    Chung, Sang Yong; Senapathi, Venkatramanan; Khakimov, Elyor; Selvam, Sekar; Oh, Yun Yeong

    2016-04-01

    This research used several geostatistical methods to assess heavy metal contaminations and their sources of sediments at Samrak Delta of Nakdong River in Busan, Korea. The mean concentration of heavy metals in sediments were Fe (16.42 %), Al (15.56 %), Mn (0.31 %), Zn, Pb, Cr (0.03 %), Ni (0.02 %) and Cu (0.008 %), which were mainly attributed to the intense industrial and irrigation activities, and also geogenic sources. Groundwater in the sediments also contains the high concentrations of heavy metals such as Fe and Mn. Canonical correlation analysis (CCA) exhibited a significant relationship between physicochemical parameters (sand, silt, clay, TOC, CaCO3) and heavy metals (Fe, Al, Mn, Zn, Pb, Cr, Ni, Cu), and the importance of physicochemical parameters in regulating the amount of heavy metals in sediments. Artificial neural network (ANN) showed a good correlation and model efficiency for simulated outputs except Fe, Pb and Zn. Silt, Clay, TOC and CaCO3 controlled the concentrations of heavy metals in sediments. Principal component analysis (PCA) produced two factor loadings of PCA 1 of Fe, Mn, Pb, TOC, Cr, silt and Al, 75.4 % in variance, and PCA 2 of Cu, Ni, Zn and CaCO3, 24.6 % in variance. It suggested that heavy metals were originated from geogenic sources and effluents from industries. Cluster analysis (CA) was helpful for the classification of contamination sources of heavy metals. This study suggests that geostatistical techniques are essentially necessary for the effective management of heavy metal contaminations and policy decision making processes to reduce the contamination level of heavy metals in deltaic region.

  4. "Geo-statistics methods and neural networks in geophysical applications: A case study"

    Science.gov (United States)

    Rodriguez Sandoval, R.; Urrutia Fucugauchi, J.; Ramirez Cruz, L. C.

    2008-12-01

    The study is focus in the Ebano-Panuco basin of northeastern Mexico, which is being explored for hydrocarbon reservoirs. These reservoirs are in limestones and there is interest in determining porosity and permeability in the carbonate sequences. The porosity maps presented in this study are estimated from application of multiattribute and neural networks techniques, which combine geophysics logs and 3-D seismic data by means of statistical relationships. The multiattribute analysis is a process to predict a volume of any underground petrophysical measurement from well-log and seismic data. The data consist of a series of target logs from wells which tie a 3-D seismic volume. The target logs are neutron porosity logs. From the 3-D seismic volume a series of sample attributes is calculated. The objective of this study is to derive a set of attributes and the target log values. The selected set is determined by a process of forward stepwise regression. The analysis can be linear or nonlinear. In the linear mode the method consists of a series of weights derived by least-square minimization. In the nonlinear mode, a neural network is trained using the select attributes as inputs. In this case we used a probabilistic neural network PNN. The method is applied to a real data set from PEMEX. For better reservoir characterization the porosity distribution was estimated using both techniques. The case shown a continues improvement in the prediction of the porosity from the multiattribute to the neural network analysis. The improvement is in the training and the validation, which are important indicators of the reliability of the results. The neural network showed an improvement in resolution over the multiattribute analysis. The final maps provide more realistic results of the porosity distribution.

  5. 4th International Geostatistics Congress

    CERN Document Server

    1993-01-01

    The contributions in this book were presented at the Fourth International Geostatistics Congress held in Tróia, Portugal, in September 1992. They provide a comprehensive account of the current state of the art of geostatistics, including recent theoretical developments and new applications. In particular, readers will find descriptions and applications of the more recent methods of stochastic simulation together with data integration techniques applied to the modelling of hydrocabon reservoirs. In other fields there are stationary and non-stationary geostatistical applications to geology, climatology, pollution control, soil science, hydrology and human sciences. The papers also provide an insight into new trends in geostatistics particularly the increasing interaction with many other scientific disciplines. This book is a significant reference work for practitioners of geostatistics both in academia and industry.

  6. 7th International Geostatistics Congress

    CERN Document Server

    Deutsch, Clayton

    2005-01-01

    The conference proceedings consist of approximately 120 technical papers presented at the Seventh International Geostatistics Congress held in Banff, Alberta, Canada in 2004. All the papers were reviewed by an international panel of leading geostatisticians. The five major sections are: theory, mining, petroleum, environmental and other applications. The first section showcases new and innovative ideas in the theoretical development of geostatistics as a whole; these ideas will have large impact on (1) the directions of future geostatistical research, and (2) the conventional approaches to heterogeneity modelling in a wide range of natural resource industries. The next four sections are focused on applications and innovations relating to the use of geostatistics in specific industries. Historically, mining, petroleum and environmental industries have embraced the use of geostatistics for uncertainty characterization, so these three industries are identified as major application areas. The last section is open...

  7. Assessment and modeling of the groundwater hydrogeochemical quality parameters via geostatistical approaches

    Science.gov (United States)

    Karami, Shawgar; Madani, Hassan; Katibeh, Homayoon; Fatehi Marj, Ahmad

    2018-03-01

    Geostatistical methods are one of the advanced techniques used for interpolation of groundwater quality data. The results obtained from geostatistics will be useful for decision makers to adopt suitable remedial measures to protect the quality of groundwater sources. Data used in this study were collected from 78 wells in Varamin plain aquifer located in southeast of Tehran, Iran, in 2013. Ordinary kriging method was used in this study to evaluate groundwater quality parameters. According to what has been mentioned in this paper, seven main quality parameters (i.e. total dissolved solids (TDS), sodium adsorption ratio (SAR), electrical conductivity (EC), sodium (Na+), total hardness (TH), chloride (Cl-) and sulfate (SO4 2-)), have been analyzed and interpreted by statistical and geostatistical methods. After data normalization by Nscore method in WinGslib software, variography as a geostatistical tool to define spatial regression was compiled and experimental variograms were plotted by GS+ software. Then, the best theoretical model was fitted to each variogram based on the minimum RSS. Cross validation method was used to determine the accuracy of the estimated data. Eventually, estimation maps of groundwater quality were prepared in WinGslib software and estimation variance map and estimation error map were presented to evaluate the quality of estimation in each estimated point. Results showed that kriging method is more accurate than the traditional interpolation methods.

  8. Assessment of geostatistical features for object-based image classification of contrasted landscape vegetation cover

    Science.gov (United States)

    de Oliveira Silveira, Eduarda Martiniano; de Menezes, Michele Duarte; Acerbi Júnior, Fausto Weimar; Castro Nunes Santos Terra, Marcela; de Mello, José Márcio

    2017-07-01

    Accurate mapping and monitoring of savanna and semiarid woodland biomes are needed to support the selection of areas of conservation, to provide sustainable land use, and to improve the understanding of vegetation. The potential of geostatistical features, derived from medium spatial resolution satellite imagery, to characterize contrasted landscape vegetation cover and improve object-based image classification is studied. The study site in Brazil includes cerrado sensu stricto, deciduous forest, and palm swamp vegetation cover. Sentinel 2 and Landsat 8 images were acquired and divided into objects, for each of which a semivariogram was calculated using near-infrared (NIR) and normalized difference vegetation index (NDVI) to extract the set of geostatistical features. The features selected by principal component analysis were used as input data to train a random forest algorithm. Tests were conducted, combining spectral and geostatistical features. Change detection evaluation was performed using a confusion matrix and its accuracies. The semivariogram curves were efficient to characterize spatial heterogeneity, with similar results using NIR and NDVI from Sentinel 2 and Landsat 8. Accuracy was significantly greater when combining geostatistical features with spectral data, suggesting that this method can improve image classification results.

  9. A Streamlined Approach by a Combination of Bioindication and Geostatistical Methods for Assessing Air Contaminants and Their Effects on Human Health in Industrialized Areas: A Case Study in Southern Brazil

    Directory of Open Access Journals (Sweden)

    Angélica B. Ferreira

    2017-09-01

    Full Text Available Industrialization in developing countries associated with urban growth results in a number of economic benefits, especially in small or medium-sized cities, but leads to a number of environmental and public health consequences. This problem is further aggravated when adequate infrastructure is lacking to monitor the environmental impacts left by industries and refineries. In this study, a new protocol was designed combining biomonitoring and geostatistics to evaluate the possible effects of shale industry emissions on human health and wellbeing. Futhermore, the traditional and expensive air quality method based on PM2.5 measuring was also used to validate the low-cost geostatistical approach. Chemical analysis was performed using Energy Dispersive X-ray Fluorescence Spectrometer (EDXRF to measure inorganic elements in tree bark and shale retorted samples in São Mateus do Sul city, Southern Brazil. Fe, S, and Si were considered potential pollutants in the study area. Distribution maps of element concentrations were generated from the dataset and used to estimate the spatial behavior of Fe, S, and Si and the range from their hot spot(s, highlighting the regions sorrounding the shale refinery. This evidence was also demonstrated in the measurements of PM2.5 concentrations, which are in agreement with the information obtained from the biomonitoring and geostatistical model. Factor and descriptive analyses performed on the concentrations of tree bark contaminants suggest that Fe, S, and Si might be used as indicators of industrial emissions. The number of cases of respiratory diseases obtained from local basic health unit were used to assess a possible correlation between shale refinery emissions and cases of repiratory disease. These data are public and may be accessed on the website of the the Brazilian Ministry of Health. Significant associations were found between the health data and refinery activities. The combination of the spatial

  10. Applications of stochastic models and geostatistical analyses to study sources and spatial patterns of soil heavy metals in a metalliferous industrial district of China

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Buqing; Liang, Tao, E-mail: liangt@igsnrr.ac.cn; Wang, Lingqing; Li, Kexin

    2014-08-15

    An extensive soil survey was conducted to study pollution sources and delineate contamination of heavy metals in one of the metalliferous industrial bases, in the karst areas of southwest China. A total of 597 topsoil samples were collected and the concentrations of five heavy metals, namely Cd, As (metalloid), Pb, Hg and Cr were analyzed. Stochastic models including a conditional inference tree (CIT) and a finite mixture distribution model (FMDM) were applied to identify the sources and partition the contribution from natural and anthropogenic sources for heavy metal in topsoils of the study area. Regression trees for Cd, As, Pb and Hg were proved to depend mostly on indicators of anthropogenic activities such as industrial type and distance from urban area, while the regression tree for Cr was found to be mainly influenced by the geogenic characteristics. The FMDM analysis showed that the geometric means of modeled background values for Cd, As, Pb, Hg and Cr were close to their background values previously reported in the study area, while the contamination of Cd and Hg were widespread in the study area, imposing potentially detrimental effects on organisms through the food chain. Finally, the probabilities of single and multiple heavy metals exceeding the threshold values derived from the FMDM were estimated using indicator kriging (IK) and multivariate indicator kriging (MVIK). The high probabilities exceeding the thresholds of heavy metals were associated with metalliferous production and atmospheric deposition of heavy metals transported from the urban and industrial areas. Geostatistics coupled with stochastic models provide an effective way to delineate multiple heavy metal pollution to facilitate improved environmental management. - Highlights: • Conditional inference tree can identify variables controlling metal distribution. • Finite mixture distribution model can partition natural and anthropogenic sources. • Geostatistics with stochastic models

  11. Applications of stochastic models and geostatistical analyses to study sources and spatial patterns of soil heavy metals in a metalliferous industrial district of China

    International Nuclear Information System (INIS)

    Zhong, Buqing; Liang, Tao; Wang, Lingqing; Li, Kexin

    2014-01-01

    An extensive soil survey was conducted to study pollution sources and delineate contamination of heavy metals in one of the metalliferous industrial bases, in the karst areas of southwest China. A total of 597 topsoil samples were collected and the concentrations of five heavy metals, namely Cd, As (metalloid), Pb, Hg and Cr were analyzed. Stochastic models including a conditional inference tree (CIT) and a finite mixture distribution model (FMDM) were applied to identify the sources and partition the contribution from natural and anthropogenic sources for heavy metal in topsoils of the study area. Regression trees for Cd, As, Pb and Hg were proved to depend mostly on indicators of anthropogenic activities such as industrial type and distance from urban area, while the regression tree for Cr was found to be mainly influenced by the geogenic characteristics. The FMDM analysis showed that the geometric means of modeled background values for Cd, As, Pb, Hg and Cr were close to their background values previously reported in the study area, while the contamination of Cd and Hg were widespread in the study area, imposing potentially detrimental effects on organisms through the food chain. Finally, the probabilities of single and multiple heavy metals exceeding the threshold values derived from the FMDM were estimated using indicator kriging (IK) and multivariate indicator kriging (MVIK). The high probabilities exceeding the thresholds of heavy metals were associated with metalliferous production and atmospheric deposition of heavy metals transported from the urban and industrial areas. Geostatistics coupled with stochastic models provide an effective way to delineate multiple heavy metal pollution to facilitate improved environmental management. - Highlights: • Conditional inference tree can identify variables controlling metal distribution. • Finite mixture distribution model can partition natural and anthropogenic sources. • Geostatistics with stochastic models

  12. Technology demonstration: geostatistical and hydrologic analysis of salt areas. Assessment of effectiveness of geologic isolation systems

    International Nuclear Information System (INIS)

    Doctor, P.G.; Oberlander, P.L.; Rice, W.A.; Devary, J.L.; Nelson, R.W.; Tucker, P.E.

    1982-09-01

    The Office of Nuclear Waste Isolation (ONWI) requested Pacific Northwest Laboratory (PNL) to: (1) use geostatistical analyses to evaluate the adequacy of hydrologic data from three salt regions, each of which contains a potential nuclear waste repository site; and (2) demonstrate a methodology that allows quantification of the value of additional data collection. The three regions examined are the Paradox Basin in Utah, the Permian Basin in Texas, and the Mississippi Study Area. Additional and new data became available to ONWI during and following these analyses; therefore, this report must be considered a methodology demonstration here would apply as illustrated had the complete data sets been available. A combination of geostatistical and hydrologic analyses was used for this demonstration. Geostatistical analyses provided an optimal estimate of the potentiometric surface from the available data, a measure of the uncertainty of that estimate, and a means for selecting and evaluating the location of future data. The hydrologic analyses included the calculation of transmissivities, flow paths, travel times, and ground-water flow rates from hypothetical repository sites. Simulation techniques were used to evaluate the effect of optimally located future data on the potentiometric surface, flow lines, travel times, and flow rates. Data availability, quality, quantity, and conformance with model assumptions differed in each of the salt areas. Report highlights for the three locations are given

  13. Technology demonstration: geostatistical and hydrologic analysis of salt areas. Assessment of effectiveness of geologic isolation systems

    Energy Technology Data Exchange (ETDEWEB)

    Doctor, P.G.; Oberlander, P.L.; Rice, W.A.; Devary, J.L.; Nelson, R.W.; Tucker, P.E.

    1982-09-01

    The Office of Nuclear Waste Isolation (ONWI) requested Pacific Northwest Laboratory (PNL) to: (1) use geostatistical analyses to evaluate the adequacy of hydrologic data from three salt regions, each of which contains a potential nuclear waste repository site; and (2) demonstrate a methodology that allows quantification of the value of additional data collection. The three regions examined are the Paradox Basin in Utah, the Permian Basin in Texas, and the Mississippi Study Area. Additional and new data became available to ONWI during and following these analyses; therefore, this report must be considered a methodology demonstration here would apply as illustrated had the complete data sets been available. A combination of geostatistical and hydrologic analyses was used for this demonstration. Geostatistical analyses provided an optimal estimate of the potentiometric surface from the available data, a measure of the uncertainty of that estimate, and a means for selecting and evaluating the location of future data. The hydrologic analyses included the calculation of transmissivities, flow paths, travel times, and ground-water flow rates from hypothetical repository sites. Simulation techniques were used to evaluate the effect of optimally located future data on the potentiometric surface, flow lines, travel times, and flow rates. Data availability, quality, quantity, and conformance with model assumptions differed in each of the salt areas. Report highlights for the three locations are given.

  14. Geostatistical ore reserve estimation for a roll-front type uranium deposit (practitioner's guide)

    International Nuclear Information System (INIS)

    Kim, Y.C.; Knudsen, H.P.

    1977-01-01

    This report comprises two parts. Part I contains illustrative examples of each phase of a geostatistical study using a roll-front type uranium deposit. Part II contains five computer programs and comprehensive users' manuals for these programs which are necessary to make a practical geostatistical study

  15. A practical primer on geostatistics

    Science.gov (United States)

    Olea, Ricardo A.

    2009-01-01

    The Challenge—Most geological phenomena are extraordinarily complex in their interrelationships and vast in their geographical extension. Ordinarily, engineers and geoscientists are faced with corporate or scientific requirements to properly prepare geological models with measurements involving a small fraction of the entire area or volume of interest. Exact description of a system such as an oil reservoir is neither feasible nor economically possible. The results are necessarily uncertain. Note that the uncertainty is not an intrinsic property of the systems; it is the result of incomplete knowledge by the observer.The Aim of Geostatistics—The main objective of geostatistics is the characterization of spatial systems that are incompletely known, systems that are common in geology. A key difference from classical statistics is that geostatistics uses the sampling location of every measurement. Unless the measurements show spatial correlation, the application of geostatistics is pointless. Ordinarily the need for additional knowledge goes beyond a few points, which explains the display of results graphically as fishnet plots, block diagrams, and maps.Geostatistical Methods—Geostatistics is a collection of numerical techniques for the characterization of spatial attributes using primarily two tools: probabilistic models, which are used for spatial data in a manner similar to the way in which time-series analysis characterizes temporal data, or pattern recognition techniques. The probabilistic models are used as a way to handle uncertainty in results away from sampling locations, making a radical departure from alternative approaches like inverse distance estimation methods.Differences with Time Series—On dealing with time-series analysis, users frequently concentrate their attention on extrapolations for making forecasts. Although users of geostatistics may be interested in extrapolation, the methods work at their best interpolating. This simple difference

  16. MIDDLE MIOCENE DEPOSITIONAL MODEL IN THE DRAVA DEPRESSION DESCRIBED BY GEOSTATISTICAL POROSITY AND THICKNESS MAPS (CASE STUDY: STARI GRADAC-BARCS NYUGAT FIELD

    Directory of Open Access Journals (Sweden)

    Tomislav Malvić

    2006-12-01

    Full Text Available Neogene depositional environments in the Drava depression can be classified in two groups. One group is of local alluvial fans, which were active during the period of Middle Miocene (Badenian extension through the entire Pannonian Basin. The second group is represented by continuous Pannonian and Pontian sedimentation starting with lacustrine environment of partly deep water and partly prodelta (turbidity fans and terminating at the delta plain sedimentation. The coarse-grained sediments of alluvial fans have the great hydrocarbon potential, because they often comprise reservoir rocks. Reservoir deposits are mostly overlain (as result of fan migration by pelitic seal deposits and sometimes including organic rich source facies. That Badenian sequences are often characterised by complete petroleum systems, what is confirmed by large number of oil and gas discoveries in such sediments in the Drava and other Croatian depressions. Alluvial environments are characterised by frequent changes of petrophysical properties, due to local character of depositional mechanism and material sources. In the presented paper, Stari Gradac-Barcs Nyugat field is selected as a case study for demonstrating the above mentioned heterogenic features of the Badenian sequences. Structural solutions are compared by maps of parameters related to depositional environment, i.e. porosity and thickness maps. Geostatistics were used for spatial extension of input dataset. The spatial variability of porosity values, i.e. reservoir quality, is interpreted by transition among different sub-environments (facies in the alluvial fan system.

  17. Constrained optimisation of spatial sampling : a geostatistical approach

    NARCIS (Netherlands)

    Groenigen, van J.W.

    1999-01-01

    Aims

    This thesis aims at the development of optimal sampling strategies for geostatistical studies. Special emphasis is on the optimal use of ancillary data, such as co-related imagery, preliminary observations and historic knowledge. Although the object of all studies

  18. Benchmarking a geostatistical procedure for the homogenisation of annual precipitation series

    Science.gov (United States)

    Caineta, Júlio; Ribeiro, Sara; Henriques, Roberto; Soares, Amílcar; Costa, Ana Cristina

    2014-05-01

    The European project COST Action ES0601, Advances in homogenisation methods of climate series: an integrated approach (HOME), has brought to attention the importance of establishing reliable homogenisation methods for climate data. In order to achieve that, a benchmark data set, containing monthly and daily temperature and precipitation data, was created to be used as a comparison basis for the effectiveness of those methods. Several contributions were submitted and evaluated by a number of performance metrics, validating the results against realistic inhomogeneous data. HOME also led to the development of new homogenisation software packages, which included feedback and lessons learned during the project. Preliminary studies have suggested a geostatistical stochastic approach, which uses Direct Sequential Simulation (DSS), as a promising methodology for the homogenisation of precipitation data series. Based on the spatial and temporal correlation between the neighbouring stations, DSS calculates local probability density functions at a candidate station to detect inhomogeneities. The purpose of the current study is to test and compare this geostatistical approach with the methods previously presented in the HOME project, using surrogate precipitation series from the HOME benchmark data set. The benchmark data set contains monthly precipitation surrogate series, from which annual precipitation data series were derived. These annual precipitation series were subject to exploratory analysis and to a thorough variography study. The geostatistical approach was then applied to the data set, based on different scenarios for the spatial continuity. Implementing this procedure also promoted the development of a computer program that aims to assist on the homogenisation of climate data, while minimising user interaction. Finally, in order to compare the effectiveness of this methodology with the homogenisation methods submitted during the HOME project, the obtained results

  19. Study of the permeability up-scaling by direct filtering of geostatistical model; Etude du changement d'echelle des permeabilites par filtrage direct du modele geostatistique

    Energy Technology Data Exchange (ETDEWEB)

    Zargar, G.

    2005-10-15

    In this thesis, we present a new approach, which consists in directly up-scaling the geostatistical permeability distribution rather than the individual realizations. Practically, filtering techniques based on. the FFT (Fast Fourier Transform), allows us to generate geostatistical images, which sample the up-scaled distributions. In the log normal case, an equivalence hydraulic criterion is proposed, allowing to re-estimate the geometric mean of the permeabilities. In the anisotropic case, the effective geometric mean becomes a tensor which depends on the level of filtering used and it can be calculated by a method of renormalisation. Then, the method was generalized for the categorial model. Numerical tests of the method were set up for isotropic, anisotropic and categorial models, which shows good agreement with theory. (author)

  20. ASSESSMENT SPATIAL VARIABILITY OF SOIL ERODIBILITY BY USING OF GEOSTATISTIC AND GIS (Case study MEHR watershed of SABZEVAR)

    OpenAIRE

    Ayoubi, S.A; M. H. Alizadeh

    2005-01-01

    Soil erodibility is one of the key factors on some sediment and soil erosion models such as USLE, MUSLE, RUSLE, AUSLE (USLE modified in LS factor) and MMF and represents like K factor and is function of particle distribution, organic mater, soil structure and ermeability. Traditional methods do not take spatial variability and estimate precision of variables in to consideration and amount of them are constant across the whole of soil series .This study was performed to assess spatial variabil...

  1. ASSESSMENT SPATIAL VARIABILITY OF SOIL ERODIBILITY BY USING OF GEOSTATISTIC AND GIS (Case study MEHR watershed of SABZEVAR

    Directory of Open Access Journals (Sweden)

    Ayoubi, S.A

    2005-05-01

    Full Text Available Soil erodibility is one of the key factors on some sediment and soil erosion models such as USLE, MUSLE, RUSLE, AUSLE (USLE modified in LS factor and MMF and represents like K factor and is function of particle distribution, organic mater, soil structure and ermeability. Traditional methods do not take spatial variability and estimate precision of variables in to consideration and amount of them are constant across the whole of soil series .This study was performed to assess spatial variability of soil erodibility and its relevant variables at MEHR watershed from Khorasan province, in northern Iran. Interested network was designed by 110 samples like nested- systematic with distance about 50, 100, 250 and 500 meter across the study area by preparing point map at GIS. Sampling points were identified in field by an Global Positioning system. Soil sampling was done at depth of 0-5cm of ground surface and permeability was studied at depth of 5-30 cm. Some soil properties such as particle distribution and organic mater were measured at laboratory. Particle size distribution was determined by Hydrometer method and Organic matter was measured by wet oxidation approach. Then spatial analysis was done. Variography analysis on soil attributes according to soil erodibility, showed that Gaussian, exponential and spherical models were the most models to predict spatial variability of soil parameters. The range of spatial dependencies was changed from 320 to 3200 m. Soil attribute maps prepared by kriging technique using models parameters. Then soil attributes were composed by Wischmeier (1978 formula in Illwis media to calculate K factor. Amount of soil erodibility changed from 0.13 to 0.91 that it's maximum and minimum was identified in east and southwest of studiedarea. Soil spatial variability pattern, is similar to silt pattern due to high effect of silt on soil rodibility, Also that is partially confirmed with geology map, indicated which soil

  2. Geostatistical coal quality control in longwall mining

    Energy Technology Data Exchange (ETDEWEB)

    Hindistan, Mehmet Ali; Tercan, Abdullah Erhan; Uenver, Bahtiyar [Hacettepe University, Dept. of Mining Engineering, Beytepe, 06800 Ankara (Turkey)

    2010-03-01

    The coal quality is an important aspect of coal mine planning. This paper presents a case study in which an underground coal mine is faced with severe penalty cost because it does not consider in situ coal quality control at all. To help short term planning of the coal production the mean calorific values of the blocks inside the production panels are estimated by kriging. The estimated calorific values are compared with those obtained from actual production. The ratio of the calorific values of actual production to estimated values is found to be 0.73 in average due to adverse effect of dilution on the quality of run-of-mine coal. This study reveals the importance of geostatistical block modelling in short term mine planning. (author)

  3. Geostatistical ore reserve estimation for a roll-front type uranium deposit (practitioner's guide)

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Y.C.; Knudsen, H.P.

    1977-01-01

    This report comprises two parts. Part I contains illustrative examples of each phase of a geostatistical study using a roll-front type uranium deposit. Part II contains five computer programs and comprehensive users' manuals for these programs which are necessary to make a practical geostatistical study. (LK)

  4. Geostatistical methods for the integrated information; Metodos geoestadisticos para la integracion de informacion

    Energy Technology Data Exchange (ETDEWEB)

    Cassiraga, E.F.; Gomez-Hernandez, J.J. [Departamento de Ingenieria Hidraulica y Medio Ambiente, Universidad Politecnica de Valencia, Valencia (Spain)

    1996-10-01

    The main objective of this report is to describe the different geostatistical techniques to use the geophysical and hydrological parameters. We analyze the characteristics of estimation methods used in others studies.

  5. Estimation of geotechnical parameters on the basis of geophysical methods and geostatistics

    Science.gov (United States)

    Brom, Aleksander; Natonik, Adrianna

    2017-12-01

    The paper presents possible implementation of ordinary cokriging and geophysical investigation on humidity data acquired in geotechnical studies. The Author describes concept of geostatistics, terminology of geostatistical modelling, spatial correlation functions, principles of solving cokriging systems, advantages of (co-)kriging in comparison with other interpolation methods, obstacles in this type of attempt. Cross validation and discussion of results was performed with an indication of prospect of applying similar procedures in various researches..

  6. Reservoir Modeling Combining Geostatistics with Markov Chain Monte Carlo Inversion

    DEFF Research Database (Denmark)

    Zunino, Andrea; Lange, Katrine; Melnikova, Yulia

    2014-01-01

    We present a study on the inversion of seismic reflection data generated from a synthetic reservoir model. Our aim is to invert directly for rock facies and porosity of the target reservoir zone. We solve this inverse problem using a Markov chain Monte Carlo (McMC) method to handle the nonlinear......, multi-step forward model (rock physics and seismology) and to provide realistic estimates of uncertainties. To generate realistic models which represent samples of the prior distribution, and to overcome the high computational demand, we reduce the search space utilizing an algorithm drawn from...... geostatistics. The geostatistical algorithm learns the multiple-point statistics from prototype models, then generates proposal models which are tested by a Metropolis sampler. The solution of the inverse problem is finally represented by a collection of reservoir models in terms of facies and porosity, which...

  7. The role of geostatistics in medical geology

    Science.gov (United States)

    Goovaerts, Pierre

    2014-05-01

    Since its development in the mining industry, geostatistics has emerged as the primary tool for spatial data analysis in various fields, ranging from earth and atmospheric sciences, to agriculture, soil science, remote sensing, and more recently environmental exposure assessment. In the last few years, these tools have been tailored to the field of medical geography or spatial epidemiology, which is concerned with the study of spatial patterns of disease incidence and mortality and the identification of potential 'causes' of disease, such as environmental exposure, diet and unhealthy behaviors, economic or socio-demographic factors. On the other hand, medical geology is an emerging interdisciplinary scientific field studying the relationship between natural geological factors and their effects on human and animal health. This paper provides an introduction to the field of medical geology with an overview of geostatistical methods available for the analysis of geological and health data. Key concepts are illustrated using the mapping of groundwater arsenic concentrations across eleven Michigan counties and the exploration of its relationship to the incidence of prostate cancer at the township level. Arsenic in drinking-water is a major problem and has received much attention because of the large human population exposed and the extremely high concentrations (e.g. 600 to 700 μg/L) recorded in many instances. Few studies have however assessed the risks associated with exposure to low levels of arsenic (say < 50 μg/L) most commonly found in drinking water in the United States. In the Michigan thumb region, arsenopyrite (up to 7% As by weight) has been identified in the bedrock of the Marshall Sandstone aquifer, one of the region's most productive aquifers. Epidemiologic studies have suggested a possible associationbetween exposure to inorganic arsenic and prostate cancer mortality, including a study of populations residing in Utah. The information available for the

  8. Geostatistical analysis of the flood risk perception queries in the village of Navaluenga (Central Spain)

    Science.gov (United States)

    Guardiola-Albert, Carolina; Díez-Herrero, Andrés; Amérigo, María; García, Juan Antonio; María Bodoque, José; Fernández-Naranjo, Nuria

    2017-04-01

    response actions, such as designing optimal evacuation routes during flood emergencies. Geostatistical tools also provide a set of interpolation techniques for the prediction of the variable value at unstudied similar locations, basing on the sample point values and other variables related with the measured variable. We attempt different geostatistical interpolation methods to obtain continuous surfaces of the risk perception and level of awareness in the study area. The use of these maps for future extensions and actualizations of the Civil Protection Plan is evaluated. References Bodoque, J. M., Amérigo, M., Díez-Herrero, A., García, J. A., Cortés, B., Ballesteros-Cánovas, J. A., & Olcina, J. (2016). Improvement of resilience of urban areas by integrating social perception in flash-flood risk management.Journal of Hydrology.

  9. 3D vadose zone modeling using geostatistical inferences

    International Nuclear Information System (INIS)

    Knutson, C.F.; Lee, C.B.

    1991-01-01

    In developing a 3D model of the 600 ft thick interbedded basalt and sediment complex that constitutes the vadose zone at the Radioactive Waste Management Complex (RWMC) at the Idaho National Engineering Laboratory (INEL) geostatistical data were captured for 12--15 parameters (e.g. permeability, porosity, saturation, etc. and flow height, flow width, flow internal zonation, etc.). This two scale data set was generated from studies of subsurface core and geophysical log suites at RWMC and from surface outcrop exposures located at the Box Canyon of the Big Lost River and from Hell's Half Acre lava field all located in the general RWMC area. Based on these currently available data, it is possible to build a 3D stochastic model that utilizes: cumulative distribution functions obtained from the geostatistical data; backstripping and rebuilding of stratigraphic units; an ''expert'' system that incorporates rules based on expert geologic analysis and experimentally derived geostatistics for providing: (a) a structural and isopach map of each layer, (b) a realization of the flow geometry of each basalt flow unit, and (c) a realization of the internal flow parameters (eg permeability, porosity, and saturation) for each flow. 10 refs., 4 figs., 1 tab

  10. Book Review Geostatistical Analysis of Compositional Data

    Energy Technology Data Exchange (ETDEWEB)

    Carle, S F

    2007-03-26

    Compositional data are represented as vector variables with individual vector components ranging between zero and a positive maximum value representing a constant sum constraint, usually unity (or 100 percent). The earth sciences are flooded with spatial distributions of compositional data, such as concentrations of major ion constituents in natural waters (e.g. mole, mass, or volume fractions), mineral percentages, ore grades, or proportions of mutually exclusive categories (e.g. a water-oil-rock system). While geostatistical techniques have become popular in earth science applications since the 1970s, very little attention has been paid to the unique mathematical properties of geostatistical formulations involving compositional variables. The book 'Geostatistical Analysis of Compositional Data' by Vera Pawlowsky-Glahn and Ricardo Olea (Oxford University Press, 2004), unlike any previous book on geostatistics, directly confronts the mathematical difficulties inherent to applying geostatistics to compositional variables. The book righteously justifies itself with prodigious referencing to previous work addressing nonsensical ranges of estimated values and error, spurious correlation, and singular cross-covariance matrices.

  11. Geostatistics and spatial analysis in biological anthropology.

    Science.gov (United States)

    Relethford, John H

    2008-05-01

    A variety of methods have been used to make evolutionary inferences based on the spatial distribution of biological data, including reconstructing population history and detection of the geographic pattern of natural selection. This article provides an examination of geostatistical analysis, a method used widely in geology but which has not often been applied in biological anthropology. Geostatistical analysis begins with the examination of a variogram, a plot showing the relationship between a biological distance measure and the geographic distance between data points and which provides information on the extent and pattern of spatial correlation. The results of variogram analysis are used for interpolating values of unknown data points in order to construct a contour map, a process known as kriging. The methods of geostatistical analysis and discussion of potential problems are applied to a large data set of anthropometric measures for 197 populations in Ireland. The geostatistical analysis reveals two major sources of spatial variation. One pattern, seen for overall body and craniofacial size, shows an east-west cline most likely reflecting the combined effects of past population dispersal and settlement. The second pattern is seen for craniofacial height and shows an isolation by distance pattern reflecting rapid spatial changes in the midlands region of Ireland, perhaps attributable to the genetic impact of the Vikings. The correspondence of these results with other analyses of these data and the additional insights generated from variogram analysis and kriging illustrate the potential utility of geostatistical analysis in biological anthropology. (c) 2008 Wiley-Liss, Inc.

  12. Identification of high-permeability subsurface structures with multiple point geostatistics and normal score ensemble Kalman filter

    Science.gov (United States)

    Zovi, Francesco; Camporese, Matteo; Hendricks Franssen, Harrie-Jan; Huisman, Johan Alexander; Salandin, Paolo

    2017-05-01

    Alluvial aquifers are often characterized by the presence of braided high-permeable paleo-riverbeds, which constitute an interconnected preferential flow network whose localization is of fundamental importance to predict flow and transport dynamics. Classic geostatistical approaches based on two-point correlation (i.e., the variogram) cannot describe such particular shapes. In contrast, multiple point geostatistics can describe almost any kind of shape using the empirical probability distribution derived from a training image. However, even with a correct training image the exact positions of the channels are uncertain. State information like groundwater levels can constrain the channel positions using inverse modeling or data assimilation, but the method should be able to handle non-Gaussianity of the parameter distribution. Here the normal score ensemble Kalman filter (NS-EnKF) was chosen as the inverse conditioning algorithm to tackle this issue. Multiple point geostatistics and NS-EnKF have already been tested in synthetic examples, but in this study they are used for the first time in a real-world case study. The test site is an alluvial unconfined aquifer in northeastern Italy with an extension of approximately 3 km2. A satellite training image showing the braid shapes of the nearby river and electrical resistivity tomography (ERT) images were used as conditioning data to provide information on channel shape, size, and position. Measured groundwater levels were assimilated with the NS-EnKF to update the spatially distributed groundwater parameters (hydraulic conductivity and storage coefficients). Results from the study show that the inversion based on multiple point geostatistics does not outperform the one with a multiGaussian model and that the information from the ERT images did not improve site characterization. These results were further evaluated with a synthetic study that mimics the experimental site. The synthetic results showed that only for a much

  13. Demonstration of a geostatistical approach to physically consistent downscaling of climate modeling simulations

    KAUST Repository

    Jha, Sanjeev Kumar

    2013-01-01

    A downscaling approach based on multiple-point geostatistics (MPS) is presented. The key concept underlying MPS is to sample spatial patterns from within training images, which can then be used in characterizing the relationship between different variables across multiple scales. The approach is used here to downscale climate variables including skin surface temperature (TSK), soil moisture (SMOIS), and latent heat flux (LH). The performance of the approach is assessed by applying it to data derived from a regional climate model of the Murray-Darling basin in southeast Australia, using model outputs at two spatial resolutions of 50 and 10 km. The data used in this study cover the period from 1985 to 2006, with 1985 to 2005 used for generating the training images that define the relationships of the variables across the different spatial scales. Subsequently, the spatial distributions for the variables in the year 2006 are determined at 10 km resolution using the 50 km resolution data as input. The MPS geostatistical downscaling approach reproduces the spatial distribution of TSK, SMOIS, and LH at 10 km resolution with the correct spatial patterns over different seasons, while providing uncertainty estimates through the use of multiple realizations. The technique has the potential to not only bridge issues of spatial resolution in regional and global climate model simulations but also in feature sharpening in remote sensing applications through image fusion, filling gaps in spatial data, evaluating downscaled variables with available remote sensing images, and aggregating/disaggregating hydrological and groundwater variables for catchment studies.

  14. Integration of dynamical data in a geostatistical model of reservoir; Integration des donnees dynamiques dans un modele geostatistique de reservoir

    Energy Technology Data Exchange (ETDEWEB)

    Costa Reis, L.

    2001-01-01

    We have developed in this thesis a methodology of integrated characterization of heterogeneous reservoirs, from geologic modeling to history matching. This methodology is applied to the reservoir PBR, situated in Campos Basin, offshore Brazil, which has been producing since June 1979. This work is an extension of two other thesis concerning geologic and geostatistical modeling of the reservoir PBR from well data and seismic information. We extended the geostatistical litho-type model to the whole reservoir by using a particular approach of the non-stationary truncated Gaussian simulation method. This approach facilitated the application of the gradual deformation method to history matching. The main stages of the methodology for dynamic data integration in a geostatistical reservoir model are presented. We constructed a reservoir model and the initial difficulties in the history matching led us to modify some choices in the geological, geostatistical and flow models. These difficulties show the importance of dynamic data integration in reservoir modeling. The petrophysical property assignment within the litho-types was done by using well test data. We used an inversion procedure to evaluate the petrophysical parameters of the litho-types. The up-scaling is a necessary stage to reduce the flow simulation time. We compared several up-scaling methods and we show that the passage from the fine geostatistical model to the coarse flow model should be done very carefully. The choice of the fitting parameter depends on the objective of the study. In the case of the reservoir PBR, where water is injected in order to improve the oil recovery, the water rate of the producing wells is directly related to the reservoir heterogeneity. Thus, the water rate was chosen as the fitting parameter. We obtained significant improvements in the history matching of the reservoir PBR. First, by using a method we have proposed, called patchwork. This method allows us to built a coherent

  15. Data analysis for radiological characterisation: Geostatistical and statistical complementarity

    International Nuclear Information System (INIS)

    Desnoyers, Yvon; Dubot, Didier

    2012-01-01

    Radiological characterisation may cover a large range of evaluation objectives during a decommissioning and dismantling (D and D) project: removal of doubt, delineation of contaminated materials, monitoring of the decontamination work and final survey. At each stage, collecting relevant data to be able to draw the conclusions needed is quite a big challenge. In particular two radiological characterisation stages require an advanced sampling process and data analysis, namely the initial categorization and optimisation of the materials to be removed and the final survey to demonstrate compliance with clearance levels. On the one hand the latter is widely used and well developed in national guides and norms, using random sampling designs and statistical data analysis. On the other hand a more complex evaluation methodology has to be implemented for the initial radiological characterisation, both for sampling design and for data analysis. The geostatistical framework is an efficient way to satisfy the radiological characterisation requirements providing a sound decision-making approach for the decommissioning and dismantling of nuclear premises. The relevance of the geostatistical methodology relies on the presence of a spatial continuity for radiological contamination. Thus geo-statistics provides reliable methods for activity estimation, uncertainty quantification and risk analysis, leading to a sound classification of radiological waste (surfaces and volumes). This way, the radiological characterization of contaminated premises can be divided into three steps. First, the most exhaustive facility analysis provides historical and qualitative information. Then, a systematic (exhaustive or not) surface survey of the contamination is implemented on a regular grid. Finally, in order to assess activity levels and contamination depths, destructive samples are collected at several locations within the premises (based on the surface survey results) and analysed. Combined with

  16. Geospatial Interpolation and Mapping of Tropospheric Ozone Pollution Using Geostatistics

    Directory of Open Access Journals (Sweden)

    Swatantra R. Kethireddy

    2014-01-01

    Full Text Available Tropospheric ozone (O3 pollution is a major problem worldwide, including in the United States of America (USA, particularly during the summer months. Ozone oxidative capacity and its impact on human health have attracted the attention of the scientific community. In the USA, sparse spatial observations for O3 may not provide a reliable source of data over a geo-environmental region. Geostatistical Analyst in ArcGIS has the capability to interpolate values in unmonitored geo-spaces of interest. In this study of eastern Texas O3 pollution, hourly episodes for spring and summer 2012 were selectively identified. To visualize the O3 distribution, geostatistical techniques were employed in ArcMap. Using ordinary Kriging, geostatistical layers of O3 for all the studied hours were predicted and mapped at a spatial resolution of 1 kilometer. A decent level of prediction accuracy was achieved and was confirmed from cross-validation results. The mean prediction error was close to 0, the root mean-standardized-prediction error was close to 1, and the root mean square and average standard errors were small. O3 pollution map data can be further used in analysis and modeling studies. Kriging results and O3 decadal trends indicate that the populace in Houston-Sugar Land-Baytown, Dallas-Fort Worth-Arlington, Beaumont-Port Arthur, San Antonio, and Longview are repeatedly exposed to high levels of O3-related pollution, and are prone to the corresponding respiratory and cardiovascular health effects. Optimization of the monitoring network proves to be an added advantage for the accurate prediction of exposure levels.

  17. Risk Assessment of Sediment Pollution Using Geostatistical Simulations

    Science.gov (United States)

    Golay, J.; Kanevski, M.

    2012-04-01

    Environmental monitoring networks (EMN) discreetly measure the intensities of continuous phenomena (e.g. pollution, temperature, etc.). Spatial prediction models, like kriging, are then used for modeling. But, they give rise to smooth representations of phenomena which leads to overestimations or underestimations of extreme values. Moreover, they do not reproduce the spatial variability of the original data and the corresponding uncertainties. When dealing with risk assessment, this is unacceptable, since extreme values must be retrieved and probabilities of exceeding given thresholds must be computed [Kanevski et al., 2009]. In order to overcome these obstacles, geostatistics provides another approach: conditional stochastic simulations. Here, the basic idea is to generate multiple estimates of variable values (e.g. pollution concentration) at every location of interest which are calculated as stochastic realizations of an unknown random function (see, for example, [Kanevski, 2008], where both theoretical concepts and real data case studies are presented in detail). Many algorithms implement this approach. The most widely used in spatial modeling are sequential Gaussian simulations/cosimulations, sequential indicator simulations/cosimulations and direct simulations. In the present study, several algorithms of geostatistical conditional simulations were applied on real data collected from Lake Geneva. The main objectives were to compare their effectiveness in reproducing global statistics (histograms, variograms) and the way they characterize the variability and uncertainty of the contamination patterns. The dataset is composed of 200 measurements of the contamination of the lake sediments by heavy metals (i.e. Cadmium, Mercury, Zinc, Copper, Titanium and Chromium). The results obtained show some differences highlighting that risk assessment can be influenced by the algorithm it relies on. Moreover, hybrid models based on machine learning algorithms and

  18. Comparison of geostatistical interpolation and remote sensing techniques for estimating long-term exposure to ambient PM2.5 concentrations across the continental United States.

    Science.gov (United States)

    Lee, Seung-Jae; Serre, Marc L; van Donkelaar, Aaron; Martin, Randall V; Burnett, Richard T; Jerrett, Michael

    2012-12-01

    A better understanding of the adverse health effects of chronic exposure to fine particulate matter (PM2.5) requires accurate estimates of PM2.5 variation at fine spatial scales. Remote sensing has emerged as an important means of estimating PM2.5 exposures, but relatively few studies have compared remote-sensing estimates to those derived from monitor-based data. We evaluated and compared the predictive capabilities of remote sensing and geostatistical interpolation. We developed a space-time geostatistical kriging model to predict PM2.5 over the continental United States and compared resulting predictions to estimates derived from satellite retrievals. The kriging estimate was more accurate for locations that were about 100 km from a monitoring station, whereas the remote sensing estimate was more accurate for locations that were > 100 km from a monitoring station. Based on this finding, we developed a hybrid map that combines the kriging and satellite-based PM2.5 estimates. We found that for most of the populated areas of the continental United States, geostatistical interpolation produced more accurate estimates than remote sensing. The differences between the estimates resulting from the two methods, however, were relatively small. In areas with extensive monitoring networks, the interpolation may provide more accurate estimates, but in the many areas of the world without such monitoring, remote sensing can provide useful exposure estimates that perform nearly as well.

  19. Geostatistics – a tool applied to the distribution of Legionella pneumophila in a hospital water system

    Directory of Open Access Journals (Sweden)

    Pasqualina Laganà

    2015-12-01

    Full Text Available [b]Introduction.[/b] Legionnaires’ disease is normally acquired by inhalation of legionellae from a contaminated environmental source. Water systems of large buildings, such as hospitals, are often contaminated with legionellae and therefore represent a potential risk for the hospital population. The aim of this study was to evaluate the potential contamination of [i]Legionella pneumophila[/i] (LP in a large hospital in Italy through georeferential statistical analysis to assess the possible sources of dispersion and, consequently, the risk of exposure for both health care staff and patients. [b]Materials and Method. [/b]LP serogroups 1 and 2–14 distribution was considered in the wards housed on two consecutive floors of the hospital building. On the basis of information provided by 53 bacteriological analysis, a ‘random’ grid of points was chosen and spatial geostatistics or [i]FAIk Kriging[/i] was applied and compared with the results of classical statistical analysis. [b]Results[/b]. Over 50% of the examined samples were positive for [i]Legionella pneumophila[/i]. LP 1 was isolated in 69% of samples from the ground floor and in 60% of sample from the first floor; LP 2–14 in 36% of sample from the ground floor and 24% from the first. The iso-estimation maps show clearly the most contaminated pipe and the difference in the diffusion of the different [i]L. pneumophila[/i] serogroups. [b]Conclusion.[/b] Experimental work has demonstrated that geostatistical methods applied to the microbiological analysis of water matrices allows a better modeling of the phenomenon under study, a greater potential for risk management and a greater choice of methods of prevention and environmental recovery to be put in place with respect to the classical statistical analysis.

  20. Uso da geoestatística para avaliar a captação automática dos níveis de pressão sonora em instalações de creche para suínos Geostatistics to evaluate the automatic acquisiton of sound pressure levels in pig nursery facilities

    Directory of Open Access Journals (Sweden)

    Giselle Borges

    2010-06-01

    Full Text Available Este trabalho teve o objetivo de estudar a influência da distribuição de decibelímetros na captação automática dos níveis de pressão sonora, em ambiente de produção intensiva de suínos. O experimento foi conduzido em sala do setor de creche de uma granja comercial de suínos situada no município de Monte Mor, Estado de São Paulo. A sala foi dividida em dez quadrantes idênticos, e os decibelímetros foram instalados no centro geométrico de cada quadrante. Utilizou-se a geoestatística para avaliar a dependência espacial entre os decibelímetros e para predizer os níveis de pressão sonora em locais onde estes não foram instalados. Os dados foram analisados pela correlação entre os decibelímetros e por intermédio da geoestatística, que possibilitou afirmar que não houve dependência espacial entre os pontos de registro dos níveis de pressão sonora. Por intermédio da interpolação dos pontos de captura utilizando o processo de krigagem, foi possível predizer os níveis de pressão sonora nos locais onde não havia decibelímetros no interior da instalação. Verificou-se homogeneidade de propagação dos níveis de pressão sonora no interior da instalação, concluindo que, para o ambiente avaliado, o uso de somente um equipamento para o registro automático dos níveis de pressão sonora é suficiente.The objective of this work was to study the influence of decibelimeters distribution in the automatic acquisition of sound pressure levels in pig nursery facilities. The experiment was conducted in a nursering room of a commercial swine's facility situated in the city of Monte Mor, State of São Paulo, Brazil. The room was divided in ten identical quadrants and the geometrical center of each quadrant was installed the decibelimeters. Geostatistics was used to evaluate the spatial dependence among the decibelimeters and to predict sound pressure levels in the places that they were not installed. Data were analyzed by the

  1. Spatial interpolation of forest conditions using co-conditional geostatistical simulation

    Science.gov (United States)

    H. Todd Mowrer

    2000-01-01

    In recent work the author used the geostatistical Monte Carlo technique of sequential Gaussian simulation (s.G.s.) to investigate uncertainty in a GIS analysis of potential old-growth forest areas. The current study compares this earlier technique to that of co-conditional simulation, wherein the spatial cross-correlations between variables are included. As in the...

  2. Forecasting Interest Rates Using Geostatistical Techniques

    Directory of Open Access Journals (Sweden)

    Giuseppe Arbia

    2015-11-01

    Full Text Available Geostatistical spatial models are widely used in many applied fields to forecast data observed on continuous three-dimensional surfaces. We propose to extend their use to finance and, in particular, to forecasting yield curves. We present the results of an empirical application where we apply the proposed method to forecast Euro Zero Rates (2003–2014 using the Ordinary Kriging method based on the anisotropic variogram. Furthermore, a comparison with other recent methods for forecasting yield curves is proposed. The results show that the model is characterized by good levels of predictions’ accuracy and it is competitive with the other forecasting models considered.

  3. Genome-wide selection by mixed model ridge regression and extensions based on geostatistical models.

    Science.gov (United States)

    Schulz-Streeck, Torben; Piepho, Hans-Peter

    2010-03-31

    The success of genome-wide selection (GS) approaches will depend crucially on the availability of efficient and easy-to-use computational tools. Therefore, approaches that can be implemented using mixed models hold particular promise and deserve detailed study. A particular class of mixed models suitable for GS is given by geostatistical mixed models, when genetic distance is treated analogously to spatial distance in geostatistics. We consider various spatial mixed models for use in GS. The analyses presented for the QTL-MAS 2009 dataset pay particular attention to the modelling of residual errors as well as of polygenetic effects. It is shown that geostatistical models are viable alternatives to ridge regression, one of the common approaches to GS. Correlations between genome-wide estimated breeding values and true breeding values were between 0.879 and 0.889. In the example considered, we did not find a large effect of the residual error variance modelling, largely because error variances were very small. A variance components model reflecting the pedigree of the crosses did not provide an improved fit. We conclude that geostatistical models deserve further study as a tool to GS that is easily implemented in a mixed model package.

  4. Geostatistical Approach to Estimating the Gold Ore Characteristics and Gold Reserves: A Case Study Daksa Area, Quang Nam Province, Viet Nam

    Science.gov (United States)

    Luan Truong, Xuan; Luong Le, Van; Quang Truong, Xuan

    2015-04-01

    Daksa gold deposit is the biggest gold deposits in Vietnam. The Daksa geological structure complicated, distributed mainly metamorphosed sedimentary NuiVu formation (PR3-?1nv2). The sulfide gold ore bodies distributed in quartz schist, quartz - biotite related to faut and distribution wing anticline. The gold ore bodies form circuits, network circuits, circuits lenses; fill the cup surface layer of the developing northeast - southwest; is the less than or west longitude north - SE. The results show that, Au and accompanying elements (Ag, Pb and Zn) have correlated pretty closely. All of its consistent with the logarithmic distribution standard, in accordance with the law of distribution of content mineral rare. The structure functions have nugget effect and spherical models with show that Au and accompanying elements special variation are changes. Au contents shown local anisotropy, no clearly anisotropy (K=1,17) and weakly anisotropy (K=1,4). Intensity mineralization of the ore bodies are quite high with demand spherical conversion coefficient ranging from 0.49 to 0.75 and from 0.66 to 0.97 (for other body). With nugget effects, ore bodies shown that it is consistent with mineralization in the ore bodies study, ore erasable, micro vein, infilling fractures in quartz vein. All of variogram presents local anisotropy, indicated gold mineralization at study area has least two-mineralization stages, consistent with the analysis of mineralography samples. By the results of the structure function study, the authors present the system optimization for exploration deposit and used to evaluate gold reserves by Ordinary Kriging. High accuracy of Kriging estimation results are expressed in the minimum Kriging variance, by compare the results calculated by some other methods (such as distance inverse weighting method, ..) and specially compare to the results of a some blocks have been exploited. Key words: Geostat and gold deposits VN. Daksa and gold mineralization. Geostat

  5. The use of sequential indicator simulation to characterize geostatistical uncertainty

    International Nuclear Information System (INIS)

    Hansen, K.M.

    1992-10-01

    Sequential indicator simulation (SIS) is a geostatistical technique designed to aid in the characterization of uncertainty about the structure or behavior of natural systems. This report discusses a simulation experiment designed to study the quality of uncertainty bounds generated using SIS. The results indicate that, while SIS may produce reasonable uncertainty bounds in many situations, factors like the number and location of available sample data, the quality of variogram models produced by the user, and the characteristics of the geologic region to be modeled, can all have substantial effects on the accuracy and precision of estimated confidence limits. It is recommended that users of SIS conduct validation studies for the technique on their particular regions of interest before accepting the output uncertainty bounds

  6. Geostatistical methods applied to field model residuals

    DEFF Research Database (Denmark)

    Maule, Fox; Mosegaard, K.; Olsen, Nils

    consists of measurement errors and unmodelled signal), and is typically assumed to be uncorrelated and Gaussian distributed. We have applied geostatistical methods to analyse the residuals of the Oersted(09d/04) field model [http://www.dsri.dk/Oersted/Field_models/IGRF_2005_candidates/], which is based......The geomagnetic field varies on a variety of time- and length scales, which are only rudimentary considered in most present field models. The part of the observed field that can not be explained by a given model, the model residuals, is often considered as an estimate of the data uncertainty (which...... on 5 years of Ørsted and CHAMP data, and includes secular variation and acceleration, as well as low-degree external (magnetospheric) and induced fields. The analysis is done in order to find the statistical behaviour of the space-time structure of the residuals, as a proxy for the data covariances...

  7. A geostatistics-informed hierarchical sensitivity analysis method for complex groundwater flow and transport modeling: GEOSTATISTICAL SENSITIVITY ANALYSIS

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Heng [Pacific Northwest National Laboratory, Richland Washington USA; Chen, Xingyuan [Pacific Northwest National Laboratory, Richland Washington USA; Ye, Ming [Department of Scientific Computing, Florida State University, Tallahassee Florida USA; Song, Xuehang [Pacific Northwest National Laboratory, Richland Washington USA; Zachara, John M. [Pacific Northwest National Laboratory, Richland Washington USA

    2017-05-01

    Sensitivity analysis is an important tool for quantifying uncertainty in the outputs of mathematical models, especially for complex systems with a high dimension of spatially correlated parameters. Variance-based global sensitivity analysis has gained popularity because it can quantify the relative contribution of uncertainty from different sources. However, its computational cost increases dramatically with the complexity of the considered model and the dimension of model parameters. In this study we developed a hierarchical sensitivity analysis method that (1) constructs an uncertainty hierarchy by analyzing the input uncertainty sources, and (2) accounts for the spatial correlation among parameters at each level of the hierarchy using geostatistical tools. The contribution of uncertainty source at each hierarchy level is measured by sensitivity indices calculated using the variance decomposition method. Using this methodology, we identified the most important uncertainty source for a dynamic groundwater flow and solute transport in model at the Department of Energy (DOE) Hanford site. The results indicate that boundary conditions and permeability field contribute the most uncertainty to the simulated head field and tracer plume, respectively. The relative contribution from each source varied spatially and temporally as driven by the dynamic interaction between groundwater and river water at the site. By using a geostatistical approach to reduce the number of realizations needed for the sensitivity analysis, the computational cost of implementing the developed method was reduced to a practically manageable level. The developed sensitivity analysis method is generally applicable to a wide range of hydrologic and environmental problems that deal with high-dimensional spatially-distributed parameters.

  8. A geostatistical model of facies-architecture and internal heterogeneity of Rotliegend-reservoirs developed from outcrop-analogues. Outcrop-analogue study Cutler Group (Utah/USA)

    Energy Technology Data Exchange (ETDEWEB)

    Irmen, A.

    2001-10-01

    The aim of this DGMK study was the collection of data that document the distribution of facies units within mixed fluvial/aeolian deposits. The Cutler Group of southeastern Utah was chosen as an outcrop analog since it contains all major lithofacies common within such deposits (aeolian dunes and interdunes, fluvial channel-films as well as lacustrine and Sabkha deposits). Because of the outstanding outcrop quality in this region, numerous detailed datasets could be collected, which allowed the visualization of size, distribution, and sedimentological inventory of the different facies in various ''paleogeographical'' maps and diagrams. A genetic model, which explains the presence of correlative horizons and cyclic patterns of deposition, could be developed. (orig.) [German] Zielsetzung dieses DGMK-Forschungsvorhabens war es, quantitative Daten zur Verteilung fazieller Einheiten innerhalb eines gemischt fluviatil/aeolischen Ablagerungsraums zu gewinnen. Die Cutler Group im Suedosten des amerikanischen Bundesstaates Utah wurde als Aufschlussanalog gewaehlt, in welchem die typischen Ablagerungen eines solchen Deposystems vorhanden sind (aeolische Duenen und -Interduenen, fluviatile Rinnenfuellungen, sowie lakustrine und Sabkha-Ablagerungen). Aufgrund der hervorragenden Aufschlusssituation konnten detaillierte Datensaetze gewonnen werden, welche die Darstellung von Groesse, bevorzugter Ausrichtung und Sedimentologie potentieller Heterogenitaetselemente entweder direkt als ''paleogeographische'' Karten, oder in statistischer Form ermoeglichten. Ein genetisches Modell erklaert die Zyklizitaet der Ablagerungen und die Anwesenheit von weitraeumig korrelierbaren Horizonten. (orig.)

  9. Optimizing Groundwater Monitoring Networks Using Integrated Statistical and Geostatistical Approaches

    Directory of Open Access Journals (Sweden)

    Jay Krishna Thakur

    2015-08-01

    Full Text Available The aim of this work is to investigate new approaches using methods based on statistics and geo-statistics for spatio-temporal optimization of groundwater monitoring networks. The formulated and integrated methods were tested with the groundwater quality data set of Bitterfeld/Wolfen, Germany. Spatially, the monitoring network was optimized using geo-statistical methods. Temporal optimization of the monitoring network was carried out using Sen’s method (1968. For geostatistical network optimization, a geostatistical spatio-temporal algorithm was used to identify redundant wells in 2- and 2.5-D Quaternary and Tertiary aquifers. Influences of interpolation block width, dimension, contaminant association, groundwater flow direction and aquifer homogeneity on statistical and geostatistical methods for monitoring network optimization were analysed. The integrated approach shows 37% and 28% redundancies in the monitoring network in Quaternary aquifer and Tertiary aquifer respectively. The geostatistical method also recommends 41 and 22 new monitoring wells in the Quaternary and Tertiary aquifers respectively. In temporal optimization, an overall optimized sampling interval was recommended in terms of lower quartile (238 days, median quartile (317 days and upper quartile (401 days in the research area of Bitterfeld/Wolfen. Demonstrated methods for improving groundwater monitoring network can be used in real monitoring network optimization with due consideration given to influencing factors.

  10. Geostatistical Spatio-Time model of crime in el Salvador: Structural and Predictive Analysis

    Directory of Open Access Journals (Sweden)

    Welman Rosa Alvarado

    2011-07-01

    Full Text Available Today, to study a geospatial and spatio-temporal phenomena requires searching statistical tools that enable the analysis of the dependency of space, time and interactions. The science that studies this kind of subjects is the Geoestatics which the goal is to predict spatial phenomenon. This science is considered the base for modeling phenomena that involves interactions between space and time. In the past 10 years, the Geostatistic had seen a great development in areas like the geology, soils, remote sensing, epidemiology, agriculture, ecology, economy, etc. In this research, the geostatistic had been apply to build a predictive map about crime in El Salvador; for that the variability of space and time together is studied to generate crime scenarios: crime hot spots are determined, crime vulnerable groups are identified, to improve political decisions and facilitate to decision makers about the insecurity in the country.

  11. The geostatistic-based spatial distribution variations of soil salts under long-term wastewater irrigation.

    Science.gov (United States)

    Wu, Wenyong; Yin, Shiyang; Liu, Honglu; Niu, Yong; Bao, Zhe

    2014-10-01

    The purpose of this study was to determine and evaluate the spatial changes in soil salinity by using geostatistical methods. The study focused on the suburb area of Beijing, where urban development led to water shortage and accelerated wastewater reuse to farm irrigation for more than 30 years. The data were then processed by GIS using three different interpolation techniques of ordinary kriging (OK), disjunctive kriging (DK), and universal kriging (UK). The normality test and overall trend analysis were applied for each interpolation technique to select the best fitted model for soil parameters. Results showed that OK was suitable for soil sodium adsorption ratio (SAR) and Na(+) interpolation; UK was suitable for soil Cl(-) and pH; DK was suitable for soil Ca(2+). The nugget-to-sill ratio was applied to evaluate the effects of structural and stochastic factors. The maps showed that the areas of non-saline soil and slight salinity soil accounted for 6.39 and 93.61%, respectively. The spatial distribution and accumulation of soil salt were significantly affected by the irrigation probabilities and drainage situation under long-term wastewater irrigation.

  12. Integration of GIS, Geostatistics, and 3-D Technology to Assess the Spatial Distribution of Soil Moisture

    Science.gov (United States)

    Betts, M.; Tsegaye, T.; Tadesse, W.; Coleman, T. L.; Fahsi, A.

    1998-01-01

    The spatial and temporal distribution of near surface soil moisture is of fundamental importance to many physical, biological, biogeochemical, and hydrological processes. However, knowledge of these space-time dynamics and the processes which control them remains unclear. The integration of geographic information systems (GIS) and geostatistics together promise a simple mechanism to evaluate and display the spatial and temporal distribution of this vital hydrologic and physical variable. Therefore, this research demonstrates the use of geostatistics and GIS to predict and display soil moisture distribution under vegetated and non-vegetated plots. The research was conducted at the Winfred Thomas Agricultural Experiment Station (WTAES), Hazel Green, Alabama. Soil moisture measurement were done on a 10 by 10 m grid from tall fescue grass (GR), alfalfa (AA), bare rough (BR), and bare smooth (BS) plots. Results indicated that variance associated with soil moisture was higher for vegetated plots than non-vegetated plots. The presence of vegetation in general contributed to the spatial variability of soil moisture. Integration of geostatistics and GIS can improve the productivity of farm lands and the precision of farming.

  13. Robust spatialization of soil water content at the scale of an agricultural field using geophysical and geostatistical methods

    Science.gov (United States)

    Henine, Hocine; Tournebize, Julien; Laurent, Gourdol; Christophe, Hissler; Cournede, Paul-Henry; Clement, Remi

    2017-04-01

    Research on the Critical Zone (CZ) is a prerequisite for undertaking issues related to ecosystemic services that human societies rely on (nutrient cycles, water supply and quality). However, while the upper part of CZ (vegetation, soil, surface water) is readily accessible, knowledge of the subsurface remains limited, due to the point-scale character of conventional direct observations. While the potential for geophysical methods to overcome this limitation is recognized, the translation of the geophysical information into physical properties or states of interest remains a challenge (e.g. the translation of soil electrical resistivity into soil water content). In this study, we propose a geostatistical framework using the Bayesian Maximum Entropy (BME) approach to assimilate geophysical and point-scale data. We especially focus on the prediction of the spatial distribution of soil water content using (1) TDR point-scale measurements of soil water content, which are considered as accurate data, and (2) soil water content data derived from electrical resistivity measurements, which are uncertain data but spatially dense. We used a synthetic dataset obtained with a vertical 2D domain to evaluate the performance of this geostatistical approach. Spatio-temporal simulations of soil water content were carried out using Hydrus-software for different scenarios: homogeneous or heterogeneous hydraulic conductivity distribution, and continuous or punctual infiltration pattern. From the simulations of soil water content, conceptual soil resistivity models were built using a forward modeling approach and point sampling of water content values, vertically ranged, were done. These two datasets are similar to field measurements of soil electrical resistivity (using electrical resistivity tomography, ERT) and soil water content (using TDR probes) obtained at the Boissy-le-Chatel site, in Orgeval catchment (East of Paris, France). We then integrated them into a specialization

  14. Topsoil moisture mapping using geostatistical techniques under different Mediterranean climatic conditions.

    Science.gov (United States)

    Martínez-Murillo, J F; Hueso-González, P; Ruiz-Sinoga, J D

    2017-10-01

    Soil mapping has been considered as an important factor in the widening of Soil Science and giving response to many different environmental questions. Geostatistical techniques, through kriging and co-kriging techniques, have made possible to improve the understanding of eco-geomorphologic variables, e.g., soil moisture. This study is focused on mapping of topsoil moisture using geostatistical techniques under different Mediterranean climatic conditions (humid, dry and semiarid) in three small watersheds and considering topography and soil properties as key factors. A Digital Elevation Model (DEM) with a resolution of 1×1m was derived from a topographical survey as well as soils were sampled to analyzed soil properties controlling topsoil moisture, which was measured during 4-years. Afterwards, some topography attributes were derived from the DEM, the soil properties analyzed in laboratory, and the topsoil moisture was modeled for the entire watersheds applying three geostatistical techniques: i) ordinary kriging; ii) co-kriging considering as co-variate topography attributes; and iii) co-kriging ta considering as co-variates topography attributes and gravel content. The results indicated topsoil moisture was more accurately mapped in the dry and semiarid watersheds when co-kriging procedure was performed. The study is a contribution to improve the efficiency and accuracy of studies about the Mediterranean eco-geomorphologic system and soil hydrology in field conditions. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Geostatistical techniques to assess the influence of soil density on sugarcane productivity

    Science.gov (United States)

    Marques, Karina; Silva, Wellington; Almeida, Ceres; Bezerra, Joel; Almeida, Brivaldo; Siqueira, Glecio

    2013-04-01

    Spatial variation in some soil properties on small distances occur even on homogeneous areas with same soil class that can influence to crop productivity. This variability must be incorporated into the procedures and techniques used in agriculture. Thus, it is necessary to know it to optimize agricultural practices. This study aimed to evaluate the influence of soil density on the sugarcane productivity by geostatistical techniques. The area is located on Rio Formoso city, Pernambuco (Brazil), at latitude 08°38'91"S and longitude 35°16'08"W, where the climate is rainy tropical. About of 243 georeferenced undisturbed soil samples (clods) were collected on lowland area at three depths (0-20, 20-40 and 40-60cm) grid spacing of 15 x 30 m. The total area has 7.5 ha, divided equally into three subareas. Statistical and geostatistics analysis were done. It was found that soil density increased with depth Bulk density and can be used as an index of relative compaction. Machine weight, track or tire design and soil water content at the time of traffic are some of the factors that determine the amount of soil compaction and resulting changes in the plant root environment. These points can have influenced the highest soil density found in subarea 1. This subarea was intensively mechanized and it presents poor drainage and seasonal flood. Based on semivariograms models fitted, we can say that soil density showed spatial dependence in subarea 1 at all depths (Gaussian (0-20cm) and spherical both 20-40 and 40-60cm). Unlike this, the models fitted to subarea 2 were to 0-20 and 40-60cm depths, exponential and on subarea 3, at 0-20cm (Gaussian). Pure nugget effect was found on 20-40cm depth at the subareas 2 and 3, and 40-60cm on the subarea 3. Subarea 1 had higher soil density and lower sugarcane productivity thus, it is known that root development and nutrient uptake are directly influenced by soil density.

  16. A space and time scale-dependent nonlinear geostatistical approach for downscaling daily precipitation and temperature

    KAUST Repository

    Jha, Sanjeev Kumar

    2015-07-21

    A geostatistical framework is proposed to downscale daily precipitation and temperature. The methodology is based on multiple-point geostatistics (MPS), where a multivariate training image is used to represent the spatial relationship between daily precipitation and daily temperature over several years. Here, the training image consists of daily rainfall and temperature outputs from the Weather Research and Forecasting (WRF) model at 50 km and 10 km resolution for a twenty year period ranging from 1985 to 2004. The data are used to predict downscaled climate variables for the year 2005. The result, for each downscaled pixel, is daily time series of precipitation and temperature that are spatially dependent. Comparison of predicted precipitation and temperature against a reference dataset indicates that both the seasonal average climate response together with the temporal variability are well reproduced. The explicit inclusion of time dependence is explored by considering the climate properties of the previous day as an additional variable. Comparison of simulations with and without inclusion of time dependence shows that the temporal dependence only slightly improves the daily prediction because the temporal variability is already well represented in the conditioning data. Overall, the study shows that the multiple-point geostatistics approach is an efficient tool to be used for statistical downscaling to obtain local scale estimates of precipitation and temperature from General Circulation Models. This article is protected by copyright. All rights reserved.

  17. Multivariate analysis and geostatistics of the fertility of a humic rhodic hapludox under coffee cultivation

    Directory of Open Access Journals (Sweden)

    Samuel de Assis Silva

    2012-04-01

    Full Text Available The spatial variability of soil and plant properties exerts great influence on the yeld of agricultural crops. This study analyzed the spatial variability of the fertility of a Humic Rhodic Hapludox with Arabic coffee, using principal component analysis, cluster analysis and geostatistics in combination. The experiment was carried out in an area under Coffea arabica L., variety Catucai 20/15 - 479. The soil was sampled at a depth 0.20 m, at 50 points of a sampling grid. The following chemical properties were determined: P, K+, Ca2+, Mg2+, Na+, S, Al3+, pH, H + Al, SB, t, T, V, m, OM, Na saturation index (SSI, remaining phosphorus (P-rem, and micronutrients (Zn, Fe, Mn, Cu and B. The data were analyzed with descriptive statistics, followed by principal component and cluster analyses. Geostatistics were used to check and quantify the degree of spatial dependence of properties, represented by principal components. The principal component analysis allowed a dimensional reduction of the problem, providing interpretable components, with little information loss. Despite the characteristic information loss of principal component analysis, the combination of this technique with geostatistical analysis was efficient for the quantification and determination of the structure of spatial dependence of soil fertility. In general, the availability of soil mineral nutrients was low and the levels of acidity and exchangeable Al were high.

  18. Geostatistical regularization operators for geophysical inverse problems on irregular meshes

    Science.gov (United States)

    Jordi, C.; Doetsch, J.; Günther, T.; Schmelzbach, C.; Robertsson, J. OA

    2018-05-01

    Irregular meshes allow to include complicated subsurface structures into geophysical modelling and inverse problems. The non-uniqueness of these inverse problems requires appropriate regularization that can incorporate a priori information. However, defining regularization operators for irregular discretizations is not trivial. Different schemes for calculating smoothness operators on irregular meshes have been proposed. In contrast to classical regularization constraints that are only defined using the nearest neighbours of a cell, geostatistical operators include a larger neighbourhood around a particular cell. A correlation model defines the extent of the neighbourhood and allows to incorporate information about geological structures. We propose an approach to calculate geostatistical operators for inverse problems on irregular meshes by eigendecomposition of a covariance matrix that contains the a priori geological information. Using our approach, the calculation of the operator matrix becomes tractable for 3-D inverse problems on irregular meshes. We tested the performance of the geostatistical regularization operators and compared them against the results of anisotropic smoothing in inversions of 2-D surface synthetic electrical resistivity tomography (ERT) data as well as in the inversion of a realistic 3-D cross-well synthetic ERT scenario. The inversions of 2-D ERT and seismic traveltime field data with geostatistical regularization provide results that are in good accordance with the expected geology and thus facilitate their interpretation. In particular, for layered structures the geostatistical regularization provides geologically more plausible results compared to the anisotropic smoothness constraints.

  19. Statistics and geostatistics: Kriging and use of hemivariogram functions in the structural investigation of uranium deposits

    International Nuclear Information System (INIS)

    Lucero Michaut, H.N.

    1980-01-01

    After presenting some general conceptual considerations regarding the theory of regionalized variables, the paper deals with specific applications of the intrinsic dispersion law to the determination, description and quantification of structures. It then briefly describes two uranium deposits in Cordoba province, the study of which yielded the basic data and parameters for compiling the geostatistical results presented. Before taking up the matter of structural interpretations, it refers briefly to the mathematical relationship between the number of sampling points available and the number of directions that can be investigated by the variogram method and also emphasizes the need for quantifying regionalization concepts on the basis of a table of absolute dimensionalities. In the case of the ''Rodolfo'' deposit it presents and comments on the hemivariograms for concentrations, thicknesses and accumulations, drawing attention at the same time to the existence of significant nest-like phenomena (gigogne structures). In this connection there is also a discussion of the case of iterative lenticular mineralization on a natural and a simulated model. The ''Schlagintweit'' deposit is dealt with in the same way, with descriptions and evaluations of the subjacent structures revealed by the hemivariographic analysis of grades, mineralization thicknesses and accumulations. This is followed by some considerations on the possibility of applying Krige and Matheron correctors in the moderation of anomalous mineralized thicknesses. In conclusion, the paper presents a ''range ellipse'' for grades; this is designed to supplement the grid of sampling points for the ''Rodolfo'' deposit by means of Matheronian kriging techniques. (author)

  20. A Classification for a Geostatistical Index of Spatial Dependence

    Directory of Open Access Journals (Sweden)

    Enio Júnior Seidel

    Full Text Available ABSTRACT: In geostatistical studies, spatial dependence can generally be described by means of the semivariogram or, in complementary form, with a single index followed by its categorization to classify the degree of such dependence. The objective of this study was to construct a categorization for the spatial dependence index (SDI proposed by Seidel and Oliveira (2014 in order to classify spatial variability in terms of weak, moderate, and strong dependence. Theoretical values were constructed from different degrees of spatial dependence, which served as a basis for calculation of the SDI. In view of the form of distribution and SDI descriptive measures, we developed a categorization for posterior classification of spatial dependence, specific to each semivariogram model. The SDI categorization was based on its median and 3rd quartile, allowing us to classify spatial dependence as weak, moderate, or strong. We established that for the spherical semivariogram: SDISpherical (% ≤ 7 % (weak spatial dependence, 7 % 15 % (strong spatial dependence; for the exponential semivariogram: SDIExponential (% ≤ 6 % (weak spatial dependence, 6 % 13 % (strong spatial dependence; and for the Gaussian semivariogram: SDIGaussian (% ≤ 9 % (weak spatial dependence, 9 % 20 % (strong spatial dependence. The proposed categorization allows the user to transform the numerical values calculated for SDI into categories of variability of spatial dependence, with adequate power for explanation and comparison.

  1. Geostatistical inference using crosshole ground-penetrating radar

    DEFF Research Database (Denmark)

    Looms, Majken C; Hansen, Thomas Mejer; Cordua, Knud Skou

    2010-01-01

    , the moisture content will reflect the variation of the physical properties of the subsurface, which determine the flow patterns in the unsaturated zone. Deterministic least-squares inversion of crosshole groundpenetrating-radar GPR traveltimes result in smooth, minimumvariance estimates of the subsurface radar...... wave velocity structure, which may diminish the utility of these images for geostatistical inference. We have used a linearized stochastic inversion technique to infer the geostatistical properties of the subsurface radar wave velocity distribution using crosshole GPR traveltimes directly. Expanding...

  2. GEOSTATISTICAL SOLUTIONS FOR DOWNSCALING REMOTELY SENSED LAND SURFACE TEMPERATURE

    Directory of Open Access Journals (Sweden)

    Q. Wang

    2017-09-01

    Full Text Available Remotely sensed land surface temperature (LST downscaling is an important issue in remote sensing. Geostatistical methods have shown their applicability in downscaling multi/hyperspectral images. In this paper, four geostatistical solutions, including regression kriging (RK, downscaling cokriging (DSCK, kriging with external drift (KED and area-to-point regression kriging (ATPRK, are applied for downscaling remotely sensed LST. Their differences are analyzed theoretically and the performances are compared experimentally using a Landsat 7 ETM+ dataset. They are also compared to the classical TsHARP method.

  3. Geostatistical parameters estimation using well test data; Determination de parametres geostatistiques par l'utilisation des donnees d'essai de puits

    Energy Technology Data Exchange (ETDEWEB)

    Gautier, Y.; Noetinger, B. [Institut Francais du Petrole (IFP), 92 - Rueil-Malmaison (France)

    2004-07-01

    In this paper we describe a new method to obtain estimations of the geostatistical parameters (GPs) such as the correlation length, l{sub c} and the permeability variance, {sigma}{sub ln}{sup 2} from well test data. In practical studies, the GPs are estimated using geological and petrophysical data, but often, these data are too scarce to give precise results. The proposed method uses the Bayesian inversion theory, in conjunction with a fast evaluation of well tests that implies up-scaling techniques. The method was tested using synthetic well-test data performed on some training images, and estimations of the underlying correlation length, l{sub c} and permeability variance, {sigma}{sub ln}{sup 2} were recovered. These estimations give a correct order of magnitude of the actual values, but as noticed in similar methods, the uncertainties are high. Once the GPs are estimated, other well established techniques can be used to get well-test matched reservoir images consistent with the geostatistical model. We will see that excellent well test data are needed, and that the method could be improved using multiple well test data. (authors)

  4. geostatistical prediction of future volcanic eruption and risk ...

    African Journals Online (AJOL)

    Admin

    within the limits of any reasonable doubt that the interval for the next major eruption that will emit lava with a volume of ..... P e rc e n ta g e. S u rv iv o r. Fig. 11: Log empirical Survivor factor for Mount Cameroon. Volcano. GEOSTATISTICAL PREDICTION OF FUTURE VOLCANIC ..... Cox, D., and Lewis, P. A. W., 1966.

  5. Geostatistics for radiological characterization: overview and application cases

    International Nuclear Information System (INIS)

    Desnoyers, Yvon

    2016-01-01

    The objective of radiological characterization is to find a suitable balance between gathering data (constrained by cost, deadlines, accessibility or radiation) and managing the issues (waste volumes, levels of activity or exposure). It is necessary to have enough information to have confidence in the results without multiplying useless data. Geo-statistics processing of data considers all available pieces of information: historical data, non-destructive measurements and laboratory analyses of samples. The spatial structure modelling is then used to produce maps and to estimate the extent of radioactive contamination (surface and depth). Quantifications of local and global uncertainties are powerful decision-making tools for better management of remediation projects at contaminated sites, and for decontamination and dismantling projects at nuclear facilities. They can be used to identify hot spots, estimate contamination of surfaces and volumes, classify radioactive waste according to thresholds, estimate source terms, and so on. The spatial structure of radioactive contamination makes the optimization of sampling (number and position of data points) particularly important. Geo-statistics methodology can help determine the initial mesh size and reduce estimation uncertainties. Several show cases are presented to illustrate why and how geo-statistics can be applied to a range of radiological characterization where investigated units can represent very small areas (a few m 2 or a few m 3 ) or very large sites (at a country scale). The focus is then put on experience gained over years in the use of geo-statistics and sampling optimization. (author)

  6. A Bayesian Markov geostatistical model for estimation of hydrogeological properties

    International Nuclear Information System (INIS)

    Rosen, L.; Gustafson, G.

    1996-01-01

    A geostatistical methodology based on Markov-chain analysis and Bayesian statistics was developed for probability estimations of hydrogeological and geological properties in the siting process of a nuclear waste repository. The probability estimates have practical use in decision-making on issues such as siting, investigation programs, and construction design. The methodology is nonparametric which makes it possible to handle information that does not exhibit standard statistical distributions, as is often the case for classified information. Data do not need to meet the requirements on additivity and normality as with the geostatistical methods based on regionalized variable theory, e.g., kriging. The methodology also has a formal way for incorporating professional judgments through the use of Bayesian statistics, which allows for updating of prior estimates to posterior probabilities each time new information becomes available. A Bayesian Markov Geostatistical Model (BayMar) software was developed for implementation of the methodology in two and three dimensions. This paper gives (1) a theoretical description of the Bayesian Markov Geostatistical Model; (2) a short description of the BayMar software; and (3) an example of application of the model for estimating the suitability for repository establishment with respect to the three parameters of lithology, hydraulic conductivity, and rock quality designation index (RQD) at 400--500 meters below ground surface in an area around the Aespoe Hard Rock Laboratory in southeastern Sweden

  7. Reducing uncertainty in geostatistical description with well testing pressure data

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, A.C.; He, Nanqun [Univ. of Tulsa, OK (United States); Oliver, D.S. [Chevron Petroleum Technology Company, La Habra, CA (United States)

    1997-08-01

    Geostatistics has proven to be an effective tool for generating realizations of reservoir properties conditioned to static data, e.g., core and log data and geologic knowledge. Due to the lack of closely spaced data in the lateral directions, there will be significant variability in reservoir descriptions generated by geostatistical simulation, i.e., significant uncertainty in the reservoir descriptions. In past work, we have presented procedures based on inverse problem theory for generating reservoir descriptions (rock property fields) conditioned to pressure data and geostatistical information represented as prior means for log-permeability and porosity and variograms. Although we have shown that the incorporation of pressure data reduces the uncertainty below the level contained in the geostatistical model based only on static information (the prior model), our previous results assumed did not explicitly account for uncertainties in the prior means and the parameters defining the variogram model. In this work, we investigate how pressure data can help detect errors in the prior means. If errors in the prior means are large and are not taken into account, realizations conditioned to pressure data represent incorrect samples of the a posteriori probability density function for the rock property fields, whereas, if the uncertainty in the prior mean is incorporated properly into the model, one obtains realistic realizations of the rock property fields.

  8. Estimating Rainfall in Rodrigues by Geostatistics: (A) Theory | Proag ...

    African Journals Online (AJOL)

    This paper introduces the geostatistical method. Originally devised to treat problems that arise when conventional statistical theory is used in estimating changes in ore grade within a mine, it is, however, an abstract theory of statistical behaviour that is applicable to many circumstances in different areas of geology and other ...

  9. Geostatistical radar-raingauge combination with nonparametric correlograms: methodological considerations and application in Switzerland

    Directory of Open Access Journals (Sweden)

    R. Schiemann

    2011-05-01

    Full Text Available Modelling spatial covariance is an essential part of all geostatistical methods. Traditionally, parametric semivariogram models are fit from available data. More recently, it has been suggested to use nonparametric correlograms obtained from spatially complete data fields. Here, both estimation techniques are compared. Nonparametric correlograms are shown to have a substantial negative bias. Nonetheless, when combined with the sample variance of the spatial field under consideration, they yield an estimate of the semivariogram that is unbiased for small lag distances. This justifies the use of this estimation technique in geostatistical applications.

    Various formulations of geostatistical combination (Kriging methods are used here for the construction of hourly precipitation grids for Switzerland based on data from a sparse realtime network of raingauges and from a spatially complete radar composite. Two variants of Ordinary Kriging (OK are used to interpolate the sparse gauge observations. In both OK variants, the radar data are only used to determine the semivariogram model. One variant relies on a traditional parametric semivariogram estimate, whereas the other variant uses the nonparametric correlogram. The variants are tested for three cases and the impact of the semivariogram model on the Kriging prediction is illustrated. For the three test cases, the method using nonparametric correlograms performs equally well or better than the traditional method, and at the same time offers great practical advantages.

    Furthermore, two variants of Kriging with external drift (KED are tested, both of which use the radar data to estimate nonparametric correlograms, and as the external drift variable. The first KED variant has been used previously for geostatistical radar-raingauge merging in Catalonia (Spain. The second variant is newly proposed here and is an extension of the first. Both variants are evaluated for the three test cases

  10. Spatial analysis of groundwater levels using Fuzzy Logic and geostatistical tools

    Science.gov (United States)

    Theodoridou, P. G.; Varouchakis, E. A.; Karatzas, G. P.

    2017-12-01

    The spatial variability evaluation of the water table of an aquifer provides useful information in water resources management plans. Geostatistical methods are often employed to map the free surface of an aquifer. In geostatistical analysis using Kriging techniques the selection of the optimal variogram is very important for the optimal method performance. This work compares three different criteria to assess the theoretical variogram that fits to the experimental one: the Least Squares Sum method, the Akaike Information Criterion and the Cressie's Indicator. Moreover, variable distance metrics such as the Euclidean, Minkowski, Manhattan, Canberra and Bray-Curtis are applied to calculate the distance between the observation and the prediction points, that affects both the variogram calculation and the Kriging estimator. A Fuzzy Logic System is then applied to define the appropriate neighbors for each estimation point used in the Kriging algorithm. The two criteria used during the Fuzzy Logic process are the distance between observation and estimation points and the groundwater level value at each observation point. The proposed techniques are applied to a data set of 250 hydraulic head measurements distributed over an alluvial aquifer. The analysis showed that the Power-law variogram model and Manhattan distance metric within ordinary kriging provide the best results when the comprehensive geostatistical analysis process is applied. On the other hand, the Fuzzy Logic approach leads to a Gaussian variogram model and significantly improves the estimation performance. The two different variogram models can be explained in terms of a fractional Brownian motion approach and of aquifer behavior at local scale. Finally, maps of hydraulic head spatial variability and of predictions uncertainty are constructed for the area with the two different approaches comparing their advantages and drawbacks.

  11. GEOSTATISTICAL BASED SUSCEPTIBILITY MAPPING OF SOIL EROSION AND OPTIMIZATION OF ITS CAUSATIVE FACTORS: A CONCEPTUAL FRAMEWORK

    Directory of Open Access Journals (Sweden)

    ABDULKADIR T. SHOLAGBERU

    2017-11-01

    Full Text Available Soil erosion hazard is the second biggest environmental challenges after population growth causing land degradation, desertification and water deterioration. Its impacts on watersheds include loss of soil nutrients, reduced reservoir capacity through siltation which may lead to flood risk, landslide, high water turbidity, etc. These problems become more pronounced in human altered mountainous areas through intensive agricultural activities, deforestation and increased urbanization among others. However, due to challenging nature of soil erosion management, there is great interest in assessing its spatial distribution and susceptibility levels. This study is thus intend to review the recent literatures and develop a novel framework for soil erosion susceptibility mapping using geostatistical based support vector machine (SVM, remote sensing and GIS techniques. The conceptual framework is to bridge the identified knowledge gaps in the area of causative factors’ (CFs selection. In this research, RUSLE model, field studies and the existing soil erosion maps for the study area will be integrated for the development of inventory map. Spatial data such as Landsat 8, digital soil and geological maps, digital elevation model and hydrological data shall be processed for the extraction of erosion CFs. GISbased SVM techniques will be adopted for the establishment of spatial relationships between soil erosion and its CFs, and subsequently for the development of erosion susceptibility maps. The results of this study include evaluation of predictive capability of GIS-based SVM in soil erosion mapping and identification of the most influential CFs for erosion susceptibility assessment. This study will serve as a guide to watershed planners and to alleviate soil erosion challenges and its related hazards.

  12. Use of stratigraphic, petrographic, hydrogeologic and geochemical information for hydrogeologic modelling based on geostatistical simulation

    International Nuclear Information System (INIS)

    Rohlig, K.J.; Fischer, H.; Poltl, B.

    2004-01-01

    This paper describes the stepwise utilization of geologic information from various sources for the construction of hydrogeological models of a sedimentary site by means of geostatistical simulation. It presents a practical application of aquifer characterisation by firstly simulating hydrogeological units and then the hydrogeological parameters. Due to the availability of a large amount of hydrogeological, geophysical and other data and information, the Gorleben site (Northern Germany) has been used for a case study in order to demonstrate the approach. The study, which has not yet been completed, tries to incorporate as much as possible of the available information and to characterise the remaining uncertainties. (author)

  13. Unsupervised classification of multivariate geostatistical data: Two algorithms

    Science.gov (United States)

    Romary, Thomas; Ors, Fabien; Rivoirard, Jacques; Deraisme, Jacques

    2015-12-01

    With the increasing development of remote sensing platforms and the evolution of sampling facilities in mining and oil industry, spatial datasets are becoming increasingly large, inform a growing number of variables and cover wider and wider areas. Therefore, it is often necessary to split the domain of study to account for radically different behaviors of the natural phenomenon over the domain and to simplify the subsequent modeling step. The definition of these areas can be seen as a problem of unsupervised classification, or clustering, where we try to divide the domain into homogeneous domains with respect to the values taken by the variables in hand. The application of classical clustering methods, designed for independent observations, does not ensure the spatial coherence of the resulting classes. Image segmentation methods, based on e.g. Markov random fields, are not adapted to irregularly sampled data. Other existing approaches, based on mixtures of Gaussian random functions estimated via the expectation-maximization algorithm, are limited to reasonable sample sizes and a small number of variables. In this work, we propose two algorithms based on adaptations of classical algorithms to multivariate geostatistical data. Both algorithms are model free and can handle large volumes of multivariate, irregularly spaced data. The first one proceeds by agglomerative hierarchical clustering. The spatial coherence is ensured by a proximity condition imposed for two clusters to merge. This proximity condition relies on a graph organizing the data in the coordinates space. The hierarchical algorithm can then be seen as a graph-partitioning algorithm. Following this interpretation, a spatial version of the spectral clustering algorithm is also proposed. The performances of both algorithms are assessed on toy examples and a mining dataset.

  14. Conditioning geostatistical simulations of a bedrock fluvial aquifer using single well pumping tests

    Science.gov (United States)

    Niazi, A.; Bentley, L. R.; Hayashi, M.

    2015-12-01

    Geostatistical simulation is a powerful tool to explore the uncertainty associated with heterogeneity in groundwater and reservoir studies. Nonetheless, conditioning simulations merely with lithological information does not utilize all of the available information and so some workers additionally condition simulations with flow data. In this study, we introduce an approach to condition geostatistical simulations of the Paskapoo Formation, which is a paleo-fluvial system consisting of sandstone channels embedded in mudstone. The conditioning data consist of two-hour single well pumping tests extracted from the public water well database in Alberta, Canada. In this approach, lithologic models of an entire watershed are simulated and conditioned with hard lithological data using transition probability geostatistics (TPROGS). Then, a segment of the simulation around a pumping well was used to populate a flow model (FEFLOW) with either sand or mudstone. The values of the hydraulic conductivity and specific storage of sand and mudstone were then adjusted to minimize the difference between simulated and actual pumping test data using the parameter estimation program PEST. If the simulated data do not adequately match the measured data, the lithologic model is updated by locally deforming the lithology distribution using the probability perturbation method (PPM) and the model parameters are again updated with PEST. This procedure is repeated until the simulated and measured data agree within a pre-determined tolerance. The procedure is repeated for each pumping well that has pumping test data. The method constrains the lithological simulations and provides estimates of hydraulic conductivity and specific storage that are consistent with the pumping test data. Eventually, the simulations will be combined in watershed scale groundwater models.

  15. 4th European Conference on Geostatistics for Environmental Applications

    CERN Document Server

    Carrera, Jesus; Gómez-Hernández, José

    2004-01-01

    The fourth edition of the European Conference on Geostatistics for Environmental Applications (geoENV IV) took place in Barcelona, November 27-29, 2002. As a proof that there is an increasing interest in environmental issues in the geostatistical community, the conference attracted over 100 participants, mostly Europeans (up to 10 European countries were represented), but also from other countries in the world. Only 46 contributions, selected out of around 100 submitted papers, were invited to be presented orally during the conference. Additionally 30 authors were invited to present their work in poster format during a special session. All oral and poster contributors were invited to submit their work to be considered for publication in this Kluwer series. All papers underwent a reviewing process, which consisted on two reviewers for oral presentations and one reviewer for posters. The book opens with one keynote paper by Philippe Naveau. It is followed by 40 papers that correspond to those presented orally d...

  16. Geostatistical analysis of soil properties at field scale using standardized data

    Science.gov (United States)

    Millan, H.; Tarquis, A. M.; Pérez, L. D.; Matos, J.; González-Posada, M.

    2012-04-01

    Indentifying areas with physical degradation is a crucial step to ameliorate the effects in soil erosion. The quantification and interpretation of spatial variability is a key issue for site-specific soil management. Geostatistics has been the main methodological tool for implementing precision agriculture using field data collected at different spatial resolutions. Even though many works have made significant contributions to the body of knowledge on spatial statistics and its applications, some other key points need to be addressed for conducting precise comparisons between soil properties using geostatistical parameters. The objectives of the present work were (i) to quantify the spatial structure of different physical properties collected from a Vertisol, (ii) to search for potential correlations between different spatial patterns and (iii) to identify relevant components through multivariate spatial analysis. The study was conducted on a Vertisol (Typic Hapludert) dedicated to sugarcane (Saccharum officinarum L.) production during the last sixty years. We used six soil properties collected from a squared grid (225 points) (penetrometer resistance (PR), total porosity, fragmentation dimension (Df), vertical electrical conductivity (ECv), horizontal electrical conductivity (ECh) and soil water content (WC)). All the original data sets were z-transformed before geostatistical analysis. Three different types of semivariogram models were necessary for fitting individual experimental semivariograms. This suggests the different natures of spatial variability patterns. Soil water content rendered the largest nugget effect (C0 = 0.933) while soil total porosity showed the largest range of spatial correlation (A = 43.92 m). The bivariate geostatistical analysis also rendered significant cross-semivariance between different paired soil properties. However, four different semivariogram models were required in that case. This indicates an underlying co

  17. Development of A Bayesian Geostatistical Data Assimilation Method and Application to the Hanford 300 Area

    Science.gov (United States)

    Murakami, Haruko

    Probabilistic risk assessment of groundwater contamination requires us to incorporate large and diverse datasets at the site into the stochastic modeling of flow and transport for prediction. In quantifying the uncertainty in our predictions, we must not only combine the best estimates of the parameters based on each dataset, but also integrate the uncertainty associated with each dataset caused by measurement errors and limited number of measurements. This dissertation presents a Bayesian geostatistical data assimilation method that integrates various types of field data for characterizing heterogeneous hydrological properties. It quantifies the parameter uncertainty as a posterior distribution conditioned on all the datasets, which can be directly used in stochastic simulations to compute possible outcomes of flow and transport processes. The goal of this framework is to remove the discontinuity between data analysis and prediction. Such a direct connection between data and prediction also makes it possible to evaluate the worth of each dataset or combined worth of multiple datasets. The synthetic studies described here confirm that the data assimilation method introduced in this dissertation successfully captures the true parameter values and predicted values within the posterior distribution. The shape of the inferred posterior distributions from the method indicates the importance of estimating the entire distribution in fully accounting for parameter uncertainty. The method is then applied to integrate multiple types of datasets at the Hanford 300 Area for characterizing a three-dimensional heterogeneous hydraulic conductivity field. Comparing the results based on the different numbers or combinations of datasets shows that increasing data do not always contribute in a straightforward way to improving the posterior distribution: increasing numbers of the same data type would not necessarily be beneficial above a certain number, and also the combined effect of

  18. 2nd European Conference on Geostatistics for Environmental Applications

    CERN Document Server

    Soares, Amílcar; Froidevaux, Roland

    1999-01-01

    The Second European Conference on Geostatistics for Environmental Ap­ plications took place in Valencia, November 18-20, 1998. Two years have past from the first meeting in Lisbon and the geostatistical community has kept active in the environmental field. In these days of congress inflation, we feel that continuity can only be achieved by ensuring quality in the papers. For this reason, all papers in the book have been reviewed by, at least, two referees, and care has been taken to ensure that the reviewer comments have been incorporated in the final version of the manuscript. We are thankful to the members of the scientific committee for their timely review of the scripts. All in all, there are three keynote papers from experts in soil science, climatology and ecology and 43 contributed papers providing a good indication of the status of geostatistics as applied in the environ­ mental field all over the world. We feel now confident that the geoENV conference series, seeded around a coffee table almost six...

  19. Home Start Evaluation Study.

    Science.gov (United States)

    High/Scope Educational Research Foundation, Ypsilanti, MI.

    Case studies of eight Home Start programs are given as the third section of an evaluation study. Communities involved are Binghamton, New York; Franklin, North Carolina; Cleveland, Ohio; Harrogate, Tennessee; Houston, Texas; Weslaco, Texas; Millville, Utah; Parkersburg, West Virginia. Although each study varies in format, each describes in detail…

  20. Spatial heterogeneity and risk factors for stunting among children under age five in Ethiopia: A Bayesian geo-statistical model.

    Directory of Open Access Journals (Sweden)

    Seifu Hagos

    Full Text Available Understanding the spatial distribution of stunting and underlying factors operating at meso-scale is of paramount importance for intervention designing and implementations. Yet, little is known about the spatial distribution of stunting and some discrepancies are documented on the relative importance of reported risk factors. Therefore, the present study aims at exploring the spatial distribution of stunting at meso- (district scale, and evaluates the effect of spatial dependency on the identification of risk factors and their relative contribution to the occurrence of stunting and severe stunting in a rural area of Ethiopia.A community based cross sectional study was conducted to measure the occurrence of stunting and severe stunting among children aged 0-59 months. Additionally, we collected relevant information on anthropometric measures, dietary habits, parent and child-related demographic and socio-economic status. Latitude and longitude of surveyed households were also recorded. Local Anselin Moran's I was calculated to investigate the spatial variation of stunting prevalence and identify potential local pockets (hotspots of high prevalence. Finally, we employed a Bayesian geo-statistical model, which accounted for spatial dependency structure in the data, to identify potential risk factors for stunting in the study area.Overall, the prevalence of stunting and severe stunting in the district was 43.7% [95%CI: 40.9, 46.4] and 21.3% [95%CI: 19.5, 23.3] respectively. We identified statistically significant clusters of high prevalence of stunting (hotspots in the eastern part of the district and clusters of low prevalence (cold spots in the western. We found out that the inclusion of spatial structure of the data into the Bayesian model has shown to improve the fit for stunting model. The Bayesian geo-statistical model indicated that the risk of stunting increased as the child's age increased (OR 4.74; 95% Bayesian credible interval [BCI]:3

  1. Redesigning rain gauges network in Johor using geostatistics and simulated annealing

    Energy Technology Data Exchange (ETDEWEB)

    Aziz, Mohd Khairul Bazli Mohd, E-mail: mkbazli@yahoo.com [Centre of Preparatory and General Studies, TATI University College, 24000 Kemaman, Terengganu, Malaysia and Department of Mathematical Sciences, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor (Malaysia); Yusof, Fadhilah, E-mail: fadhilahy@utm.my [Department of Mathematical Sciences, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor (Malaysia); Daud, Zalina Mohd, E-mail: zalina@ic.utm.my [UTM Razak School of Engineering and Advanced Technology, Universiti Teknologi Malaysia, UTM KL, 54100 Kuala Lumpur (Malaysia); Yusop, Zulkifli, E-mail: zulyusop@utm.my [Institute of Environmental and Water Resource Management (IPASA), Faculty of Civil Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor (Malaysia); Kasno, Mohammad Afif, E-mail: mafifkasno@gmail.com [Malaysia - Japan International Institute of Technology (MJIIT), Universiti Teknologi Malaysia, UTM KL, 54100 Kuala Lumpur (Malaysia)

    2015-02-03

    Recently, many rainfall network design techniques have been developed, discussed and compared by many researchers. Present day hydrological studies require higher levels of accuracy from collected data. In numerous basins, the rain gauge stations are located without clear scientific understanding. In this study, an attempt is made to redesign rain gauge network for Johor, Malaysia in order to meet the required level of accuracy preset by rainfall data users. The existing network of 84 rain gauges in Johor is optimized and redesigned into a new locations by using rainfall, humidity, solar radiation, temperature and wind speed data collected during the monsoon season (November - February) of 1975 until 2008. This study used the combination of geostatistics method (variance-reduction method) and simulated annealing as the algorithm of optimization during the redesigned proses. The result shows that the new rain gauge location provides minimum value of estimated variance. This shows that the combination of geostatistics method (variance-reduction method) and simulated annealing is successful in the development of the new optimum rain gauge system.

  2. Redesigning rain gauges network in Johor using geostatistics and simulated annealing

    International Nuclear Information System (INIS)

    Aziz, Mohd Khairul Bazli Mohd; Yusof, Fadhilah; Daud, Zalina Mohd; Yusop, Zulkifli; Kasno, Mohammad Afif

    2015-01-01

    Recently, many rainfall network design techniques have been developed, discussed and compared by many researchers. Present day hydrological studies require higher levels of accuracy from collected data. In numerous basins, the rain gauge stations are located without clear scientific understanding. In this study, an attempt is made to redesign rain gauge network for Johor, Malaysia in order to meet the required level of accuracy preset by rainfall data users. The existing network of 84 rain gauges in Johor is optimized and redesigned into a new locations by using rainfall, humidity, solar radiation, temperature and wind speed data collected during the monsoon season (November - February) of 1975 until 2008. This study used the combination of geostatistics method (variance-reduction method) and simulated annealing as the algorithm of optimization during the redesigned proses. The result shows that the new rain gauge location provides minimum value of estimated variance. This shows that the combination of geostatistics method (variance-reduction method) and simulated annealing is successful in the development of the new optimum rain gauge system

  3. Redesigning rain gauges network in Johor using geostatistics and simulated annealing

    Science.gov (United States)

    Aziz, Mohd Khairul Bazli Mohd; Yusof, Fadhilah; Daud, Zalina Mohd; Yusop, Zulkifli; Kasno, Mohammad Afif

    2015-02-01

    Recently, many rainfall network design techniques have been developed, discussed and compared by many researchers. Present day hydrological studies require higher levels of accuracy from collected data. In numerous basins, the rain gauge stations are located without clear scientific understanding. In this study, an attempt is made to redesign rain gauge network for Johor, Malaysia in order to meet the required level of accuracy preset by rainfall data users. The existing network of 84 rain gauges in Johor is optimized and redesigned into a new locations by using rainfall, humidity, solar radiation, temperature and wind speed data collected during the monsoon season (November - February) of 1975 until 2008. This study used the combination of geostatistics method (variance-reduction method) and simulated annealing as the algorithm of optimization during the redesigned proses. The result shows that the new rain gauge location provides minimum value of estimated variance. This shows that the combination of geostatistics method (variance-reduction method) and simulated annealing is successful in the development of the new optimum rain gauge system.

  4. Mapping monthly rainfall data in Galicia (NW Spain using inverse distances and geostatistical methods

    Directory of Open Access Journals (Sweden)

    P. Sande-Fouz

    2007-04-01

    Full Text Available In this paper, results from three different interpolation techniques based on Geostatistics (ordinary kriging, kriging with external drift and conditional simulation and one deterministic method (inverse distances for mapping total monthly rainfall are compared. The study data set comprised total monthly rainfall from 1998 till 2001 corresponding to a maximum of 121 meteorological stations irregularly distributed in the region of Galicia (NW Spain. Furthermore, a raster Geographic Information System (GIS was used for spatial interpolation with a 500×500 m grid digital elevation model. Inverse distance technique was appropriate for a rapid estimation of the rainfall at the studied scale. In order to apply geostatistical interpolation techniques, a spatial dependence analysis was performed; rainfall spatial dependence was observed in 33 out of 48 months analysed, the rest of the rainfall data sets presented a random behaviour. Different values of the semivariogram parameters caused the smoothing in the maps obtained by ordinary kriging. Kriging with external drift results were according to former studies which showed the influence of topography. Conditional simulation is considered to give more realistic results; however, this consideration must be confirmed with new data.

  5. 3D Geostatistical Modeling and Uncertainty Analysis in a Carbonate Reservoir, SW Iran

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Kamali

    2013-01-01

    Full Text Available The aim of geostatistical reservoir characterization is to utilize wide variety of data, in different scales and accuracies, to construct reservoir models which are able to represent geological heterogeneities and also quantifying uncertainties by producing numbers of equiprobable models. Since all geostatistical methods used in estimation of reservoir parameters are inaccurate, modeling of “estimation error” in form of uncertainty analysis is very important. In this paper, the definition of Sequential Gaussian Simulation has been reviewed and construction of stochastic models based on it has been discussed. Subsequently ranking and uncertainty quantification of those stochastically populated equiprobable models and sensitivity study of modeled properties have been presented. Consequently, the application of sensitivity analysis on stochastic models of reservoir horizons, petrophysical properties, and stochastic oil-water contacts, also their effect on reserve, clearly shows any alteration in the reservoir geometry has significant effect on the oil in place. The studied reservoir is located at carbonate sequences of Sarvak Formation, Zagros, Iran; it comprises three layers. The first one which is located beneath the cap rock contains the largest portion of the reserve and other layers just hold little oil. Simulations show that average porosity and water saturation of the reservoir is about 20% and 52%, respectively.

  6. Geostatistics: a common link between medical geography, mathematical geology, and medical geology.

    Science.gov (United States)

    Goovaerts, P

    2014-08-01

    Since its development in the mining industry, geostatistics has emerged as the primary tool for spatial data analysis in various fields, ranging from earth and atmospheric sciences to agriculture, soil science, remote sensing, and more recently environmental exposure assessment. In the last few years, these tools have been tailored to the field of medical geography or spatial epidemiology, which is concerned with the study of spatial patterns of disease incidence and mortality and the identification of potential 'causes' of disease, such as environmental exposure, diet and unhealthy behaviours, economic or socio-demographic factors. On the other hand, medical geology is an emerging interdisciplinary scientific field studying the relationship between natural geological factors and their effects on human and animal health. This paper provides an introduction to the field of medical geology with an overview of geostatistical methods available for the analysis of geological and health data. Key concepts are illustrated using the mapping of groundwater arsenic concentration across eleven Michigan counties and the exploration of its relationship to the incidence of prostate cancer at the township level.

  7. Downscaling remotely sensed imagery using area-to-point cokriging and multiple-point geostatistical simulation

    Science.gov (United States)

    Tang, Yunwei; Atkinson, Peter M.; Zhang, Jingxiong

    2015-03-01

    A cross-scale data integration method was developed and tested based on the theory of geostatistics and multiple-point geostatistics (MPG). The goal was to downscale remotely sensed images while retaining spatial structure by integrating images at different spatial resolutions. During the process of downscaling, a rich spatial correlation model in the form of a training image was incorporated to facilitate reproduction of similar local patterns in the simulated images. Area-to-point cokriging (ATPCK) was used as locally varying mean (LVM) (i.e., soft data) to deal with the change of support problem (COSP) for cross-scale integration, which MPG cannot achieve alone. Several pairs of spectral bands of remotely sensed images were tested for integration within different cross-scale case studies. The experiment shows that MPG can restore the spatial structure of the image at a fine spatial resolution given the training image and conditioning data. The super-resolution image can be predicted using the proposed method, which cannot be realised using most data integration methods. The results show that ATPCK-MPG approach can achieve greater accuracy than methods which do not account for the change of support issue.

  8. Evaluating factorial kriging for seismic attributes filtering: a geostatistical filter applied to reservoir characterization; Avaliacao da krigagem fatorial na filtragem de atributos sismicos: um filtro geoestatistico aplicado a caracterizacao de reservatorios

    Energy Technology Data Exchange (ETDEWEB)

    Mundim, Evaldo Cesario

    1999-02-01

    In this dissertation the Factorial Kriging analysis for the filtering of seismic attributes applied to reservoir characterization is considered. Factorial Kriging works in the spatial, domain in a similar way to the Spectral Analysis in the frequency domain. The incorporation of filtered attributes via External Drift Kriging and Collocated Cokriging in the estimate of reservoir characterization is discussed. Its relevance for the reservoir porous volume calculation is also evaluated based on comparative analysis of the volume risk curves derived from stochastic conditional simulations with collocated variable and stochastic conditional simulations with collocated variable and stochastic conditional simulations with external drift. results prove Factorial Kriging as an efficient technique for the filtering of seismic attributes images, of which geologic features are enhanced. The attribute filtering improves the correlation between the attributes and the well data and the estimates of the reservoir properties. The differences between the estimates obtained by External Drift Kriging and Collocated Cokriging are also reduced. (author)

  9. Evaluation of epidemiological studies

    International Nuclear Information System (INIS)

    Breckow, J.

    1995-01-01

    The publication is intended for readers with a professional background in radiation protection who are not experts in the field of epidemiology. The potentials and the limits of epidemiology are shown and concepts and terminology of radioepidemilogic studies as well as epidemiology in general are explained, in order to provide the necessary basis for understanding or performing evaluations of epidemiologic studies. (orig./VHE) [de

  10. Geo-statistical modeling to evaluate the socio-economic impacts of households in the context of low-lying areas conversion in Colombo metropolitan region-Sri Lanka

    Science.gov (United States)

    Hemakumara, GPTS; Rainis, Ruslan

    2015-02-01

    Living in Low-lying areas is a challenging task, but due to the lack of suitable land at affordable prices, thousands of householders have been establishing their own houses on Low-lying areas. Manipulation and conversion of low lying areas have led to an increase in the frequency and severity of micro disasters because the cumulative effect of these settlements is very high. Therefore, it is needed to examine how individual households have been emerging in Low-lying areas. This process is primarily influenced and controlled by Socio-economic factors. In the field survey conducted for this study, 388 householders were interviewed face to face to obtain the primary data. Collected data were applied to the Multivariate binary logistic Model. The Dependent variable of the model was set as Stable Houses and Non-Stable Houses based on the weighted values that were obtained from the field observations. Independent variables of this study are nine key aspects of the socio-economic conditions in these areas. Units of analysis of the study were taken as individual housing plots in the study area. The particular combination of Socio-Economic factors that exerted influence on each housing plot was measured using predicted probability value of logistic model and linked it with GIS land plot's map. Accuracy of Final Model is 86.9 % and probability level of influencing factors given a clear idea about household distribution and status while providing guidance about how the planning authorities should monitor and manage low lying areas, taking into consideration the present housing condition of these areas.

  11. Mercury emissions from coal combustion in Silesia, analysis using geostatistics

    Science.gov (United States)

    Zasina, Damian; Zawadzki, Jaroslaw

    2015-04-01

    Data provided by the UNEP's report on mercury [1] shows that solid fuel combustion in significant source of mercury emission to air. Silesia, located in southwestern Poland, is notably affected by mercury emission due to being one of the most industrialized Polish regions: the place of coal mining, production of metals, stone mining, mineral quarrying and chemical industry. Moreover, Silesia is the region with high population density. People are exposed to severe risk of mercury emitted from both: industrial and domestic sources (i.e. small household furnaces). Small sources have significant contribution to total emission of mercury. Official and statistical analysis, including prepared for international purposes [2] did not provide data about spatial distribution of the mercury emitted to air, however number of analysis on Polish public power and energy sector had been prepared so far [3; 4]. The distribution of locations exposed for mercury emission from small domestic sources is interesting matter merging information from various sources: statistical, economical and environmental. This paper presents geostatistical approach to distibution of mercury emission from coal combustion. Analysed data organized in 2 independent levels: individual, bottom-up approach derived from national emission reporting system [5; 6] and top down - regional data calculated basing on official statistics [7]. Analysis, that will be presented, will include comparison of spatial distributions of mercury emission using data derived from sources mentioned above. Investigation will include three voivodeships of Poland: Lower Silesian, Opole (voivodeship) and Silesian using selected geostatistical methodologies including ordinary kriging [8]. References [1] UNEP. Global Mercury Assessment 2013: Sources, Emissions, Releases and Environmental Transport. UNEP Chemicals Branch, Geneva, Switzerland, 2013. [2] NCEM. Poland's Informative Inventory Report 2014. NCEM at the IEP-NRI, 2014. http

  12. Spatial distribution of Munida intermedia and M. sarsi (crustacea: Anomura) on the Galician continental shelf (NW Spain): Application of geostatistical analysis

    Science.gov (United States)

    Freire, J.; González-Gurriarán, E.; Olaso, I.

    1992-12-01

    Geostatistical methodology was used to analyse spatial structure and distribution of the epibenthic crustaceans Munida intermedia and M. sarsi within sets of data which had been collected during three survey cruises carried out on the Galician continental shelf (1983 and 1984). This study investigates the feasibility of using geostatistics for data collected according to traditional methods and of enhancing such methodology. The experimental variograms were calculated (pooled variance minus spatial covariance between samples taken one pair at a time vs. distance) and fitted to a 'spherical' model. The spatial structure model was used to estimate the abundance and distribution of the populations studied using the technique of kriging. The species display spatial structures, which are well marked during high density periods and in some areas (especially northern shelf). Geostatistical analysis allows identification of the density gradients in space as well as the patch grain along the continental shelf of 16-25 km diameter for M. intermedia and 12-20 km for M. sarsi. Patches of both species have a consistent location throughout the different cruises. As in other geographical areas, M. intermedia and M. sarsi usually appear at depths ranging from 200 to 500 m, with the highest densities in the continental shelf area located between Fisterra and Estaca de Bares. Althouh sampling was not originally designed specifically for geostatistics, this assay provides a measurement of spatial covariance, and shows variograms with variable structure depending on population density and geographical area. These ideas are useful in improving the design of future sampling cruises.

  13. Variabilidade espacial da agregação do solo avaliada pela geometria fractal e geoestatística Spatial variability of soil aggregation evaluated by fractal geometry and geostatistics

    Directory of Open Access Journals (Sweden)

    J. R. P. Carvalho

    2004-02-01

    Full Text Available Este trabalho teve por objetivo explorar a aplicabilidade da teoria de fractais no estudo da variabilidade espacial em agregação de solo. A geometria de fractais tem sido proposta como um modelo para a distribuição de tamanho de partículas. A distribuição do tamanho de agregados do solo, expressos em termos de massa, é apresentada. Os parâmetros do modelo, tais como: a dimensão fractal D, medida representativa da fragmentação do solo (quanto maior seu valor, maior a fragmentação, e o tamanho do maior agregado R L foram definidos como ferramentas descritivas para a agregação do solo. Os agregados foram coletados em uma profundidade de 0-10 cm de um Latossolo Vermelho distrófico típico álico textura argilosa, em Angatuba, São Paulo. Uma grade regular de 100 x 100 m foi usada e a amostragem realizada em 76 pontos nos quais se determinou a distribuição de agregados por via úmida, usando água, álcool e benzeno como pré-tratamentos. Pelo exame de semivariogramas, constatou-se a ocorrência de dependência espacial. A krigagem ordinária foi usada como interpolador e mapas de contorno mostraram-se de grande utilidade na descrição da variabilidade espacial de agregação do solo.This work explored the applicability of the fractal theory for studies into space variability of soil aggregation. Fractal geometry has become a model for soil size particle distribution. The distribution of soil aggregates in terms of its mass was obtained, and model parameters such as the fractal dimension D, which is a representative measure of the soil fragmentation (the larger its value, the larger the fragmentation, and the largest aggregate size R L were defined as descriptive tools for soil aggregation. The aggregates were collected at a depth of 0-10 cm of a Clayey Ferrasol in Angatuba, São Paulo. A regular grid of 100 x 100 m was used and samples collected from 76 points, where the aggregate distribution was determined by humid way (water

  14. Geostatistical modelling of household malaria in Malawi

    Science.gov (United States)

    Chirombo, J.; Lowe, R.; Kazembe, L.

    2012-04-01

    Malaria is one of the most important diseases in the world today, common in tropical and subtropical areas with sub-Saharan Africa being the region most burdened, including Malawi. This region has the right combination of biotic and abiotic components, including socioeconomic, climatic and environmental factors that sustain transmission of the disease. Differences in these conditions across the country consequently lead to spatial variation in risk of the disease. Analysis of nationwide survey data that takes into account this spatial variation is crucial in a resource constrained country like Malawi for targeted allocation of scare resources in the fight against malaria. Previous efforts to map malaria risk in Malawi have been based on limited data collected from small surveys. The Malaria Indicator Survey conducted in 2010 is the most comprehensive malaria survey carried out in Malawi and provides point referenced data for the study. The data has been shown to be spatially correlated. We use Bayesian logistic regression models with spatial correlation to model the relationship between malaria presence in children and covariates such as socioeconomic status of households and meteorological conditions. This spatial model is then used to assess how malaria varies spatially and a malaria risk map for Malawi is produced. By taking intervention measures into account, the developed model is used to assess whether they have an effect on the spatial distribution of the disease and Bayesian kriging is used to predict areas where malaria risk is more likely to increase. It is hoped that this study can help reveal areas that require more attention from the authorities in the continuing fight against malaria, particularly in children under the age of five.

  15. Cross-covariance functions for multivariate geostatistics

    KAUST Repository

    Genton, Marc G.

    2015-05-01

    Continuously indexed datasets with multiple variables have become ubiquitous in the geophysical, ecological, environmental and climate sciences, and pose substantial analysis challenges to scientists and statisticians. For many years, scientists developed models that aimed at capturing the spatial behavior for an individual process; only within the last few decades has it become commonplace to model multiple processes jointly. The key difficulty is in specifying the cross-covariance function, that is, the function responsible for the relationship between distinct variables. Indeed, these cross-covariance functions must be chosen to be consistent with marginal covariance functions in such a way that the second-order structure always yields a nonnegative definite covariance matrix. We review the main approaches to building cross-covariance models, including the linear model of coregionalization, convolution methods, the multivariate Matérn and nonstationary and space-time extensions of these among others. We additionally cover specialized constructions, including those designed for asymmetry, compact support and spherical domains, with a review of physics-constrained models. We illustrate select models on a bivariate regional climate model output example for temperature and pressure, along with a bivariate minimum and maximum temperature observational dataset; we compare models by likelihood value as well as via cross-validation co-kriging studies. The article closes with a discussion of unsolved problems. © Institute of Mathematical Statistics, 2015.

  16. Rainfall variation by geostatistical interpolation method

    Directory of Open Access Journals (Sweden)

    Glauber Epifanio Loureiro

    2013-08-01

    Full Text Available This article analyses the variation of rainfall in the Tocantins-Araguaia hydrographic region in the last two decades, based upon the rain gauge stations of the ANA (Brazilian National Water Agency HidroWeb database for the years 1983, 1993 and 2003. The information was systemized and treated with Hydrologic methods such as method of contour and interpolation for ordinary kriging. The treatment considered the consistency of the data, the density of the space distribution of the stations and the periods of study. The results demonstrated that the total volume of water precipitated annually did not change significantly in the 20 years analyzed. However, a significant variation occurred in its spatial distribution. By analyzing the isohyet it was shown that there is a displacement of the precipitation at Tocantins Baixo (TOB of approximately 10% of the total precipitated volume. This displacement can be caused by global change, by anthropogenic activities or by regional natural phenomena. However, this paper does not explore possible causes of the displacement.

  17. Multi-Criteria GIS Methodology Focused on the Location of Optimal Places for Small Hydro Power Via Hydrological and Geostatistic Aplications; Metodologia SIG Multicriterio Enfocada a la Localizacion de Enclaves Optimos para Centrales de Minihidroelectricas mediante Aplicaciones Hidrologicas y Geoestadisticas

    Energy Technology Data Exchange (ETDEWEB)

    Paz, C. de la

    2013-02-01

    The main objective of this research is the development of a location methodology for sitting optimization of small hydro power (SHP) centrals. In order of achieve this goal, a Multi-Criteria Evaluation (MCE) methodology implemented through the use of tools in a GIS environment: Spatial Analysis, Geostatistic Analysis, and Hydrology have been developed. This methodology includes two different models based on the same MCE process. The substantial difference of both models is in the input data and the tools applied to estimate the energy resource and the principal factor of the methodology (caudal or accumulated flow). The first model is generated from caudal data obtained in the study area (El Bierzo), and the second one from pluviometric data and Digital Terrain Model (DTM). Both models include viability maps with greater ability areas to locate SHP facilities. As an additional objective, the study allows contrasting the results of the two developed models to evaluate their similarity. (Author)

  18. Spatial Variability and Geostatistical Prediction of Some Soil Hydraulic Coefficients of a Calcareous Soil

    Directory of Open Access Journals (Sweden)

    Ali Akbar Moosavi

    2017-02-01

    diffusivity were week, whereas, the spatial correlation classes of the other studied soil hydraulic attributes were moderate. Results revealed that the Inverse Distance Weighting method was the most suitable approach for the prediction of all studied soil hydraulic attributes in the present study. Comparison of the calculated statistical evaluation measures (i.e. Determination coefficient, R2, Mean residual error, MRE, mean square error, MSE, Normalized mean square error, NRMSE and geometric mean error ratio, GMER and the final determined order of precision showed that the most and the least accurate predictions were obtained for Ks and Фm, respectively. Conclusion: It is suggested in the cases that we need to map the hydraulic attributes or need their quantities in a large number; geostatistical prediction be performed using the limited measurements to reduce the needed time and costs.

  19. Bayesian geostatistics in health cartography: the perspective of malaria.

    Science.gov (United States)

    Patil, Anand P; Gething, Peter W; Piel, Frédéric B; Hay, Simon I

    2011-06-01

    Maps of parasite prevalences and other aspects of infectious diseases that vary in space are widely used in parasitology. However, spatial parasitological datasets rarely, if ever, have sufficient coverage to allow exact determination of such maps. Bayesian geostatistics (BG) is a method for finding a large sample of maps that can explain a dataset, in which maps that do a better job of explaining the data are more likely to be represented. This sample represents the knowledge that the analyst has gained from the data about the unknown true map. BG provides a conceptually simple way to convert these samples to predictions of features of the unknown map, for example regional averages. These predictions account for each map in the sample, yielding an appropriate level of predictive precision.

  20. Geostatistical modeling of groundwater properties and assessment of their uncertainties

    International Nuclear Information System (INIS)

    Honda, Makoto; Yamamoto, Shinya; Sakurai, Hideyuki; Suzuki, Makoto; Sanada, Hiroyuki; Matsui, Hiroya; Sugita, Yutaka

    2010-01-01

    The distribution of groundwater properties is important for understanding of the deep underground hydrogeological environments. This paper proposes a geostatistical system for modeling the groundwater properties which have a correlation with the ground resistivity data obtained from widespread and exhaustive survey. That is, the methodology for the integration of resistivity data measured by various methods and the methodology for modeling the groundwater properties using the integrated resistivity data has been developed. The proposed system has also been validated using the data obtained in the Horonobe Underground Research Laboratory project. Additionally, the quantification of uncertainties in the estimated model has been tried by numerical simulations based on the data. As a result, the uncertainties of the proposal model have been estimated lower than other traditional model's. (author)

  1. A Geostatistical Approach to Indoor Surface Sampling Strategies

    DEFF Research Database (Denmark)

    Schneider, Thomas; Petersen, Ole Holm; Nielsen, Allan Aasbjerg

    1990-01-01

    using the global information. Then methods for choosing a proper sampling area for a single sample of dust on a table are given. The global contamination of an object is determined by a maximum likelihood estimator. Finally, it is shown how specified experimental goals can be included to determine......Particulate surface contamination is of concern in production industries such as food processing, aerospace, electronics and semiconductor manufacturing. There is also an increased awareness that surface contamination should be monitored in industrial hygiene surveys. A conceptual and theoretical...... framework for designing sampling strategies is thus developed. The distribution and spatial correlation of surface contamination can be characterized using concepts from geostatistical science, where spatial applications of statistics is most developed. The theory is summarized and particulate surface...

  2. Geostatistical Interpolation of Particle-Size Curves in Heterogeneous Aquifers

    Science.gov (United States)

    Guadagnini, A.; Menafoglio, A.; Secchi, P.

    2013-12-01

    We address the problem of predicting the spatial field of particle-size curves (PSCs) from measurements associated with soil samples collected at a discrete set of locations within an aquifer system. Proper estimates of the full PSC are relevant to applications related to groundwater hydrology, soil science and geochemistry and aimed at modeling physical and chemical processes occurring in heterogeneous earth systems. Hence, we focus on providing kriging estimates of the entire PSC at unsampled locations. To this end, we treat particle-size curves as cumulative distribution functions, model their densities as functional compositional data and analyze them by embedding these into the Hilbert space of compositional functions endowed with the Aitchison geometry. On this basis, we develop a new geostatistical methodology for the analysis of spatially dependent functional compositional data. Our functional compositional kriging (FCK) approach allows providing predictions at unsampled location of the entire particle-size curve, together with a quantification of the associated uncertainty, by fully exploiting both the functional form of the data and their compositional nature. This is a key advantage of our approach with respect to traditional methodologies, which treat only a set of selected features (e.g., quantiles) of PSCs. Embedding the full PSC into a geostatistical analysis enables one to provide a complete characterization of the spatial distribution of lithotypes in a reservoir, eventually leading to improved predictions of soil hydraulic attributes through pedotransfer functions as well as of soil geochemical parameters which are relevant in sorption/desorption and cation exchange processes. We test our new method on PSCs sampled along a borehole located within an alluvial aquifer near the city of Tuebingen, Germany. The quality of FCK predictions is assessed through leave-one-out cross-validation. A comparison between hydraulic conductivity estimates obtained

  3. Geostatistical analysis of soil gas data in a high seismic intermontane basin: Fucino Plain, central Italy

    Science.gov (United States)

    Ciotoli, G.; Lombardi, S.; Annunziatellis, A.

    2007-05-01

    Numerous soil gas measurements of four gaseous species with very different geochemical behaviors were performed in the Fucino Basin, an area characterized by known and inferred structural discontinuities. A comprehensive statistical and geostatistical treatment of these data followed in order to provide insight into the spatial influence of tectonic discontinuities and geology on deep-seated gas migration toward the surface. The results yielded anomalies with different features, reflecting the different gas-bearing properties of the eastern seismogenic faults related to the 1915 earthquake (Mb = 7.0) and the hidden structural features occurring in the western side of the plain. In particular, this approach demonstrates that soil gas concentration (i.e., Rn and CO2) can identify the simpler normal faults of the eastern sector of the plain. In contrast, the more pervasive fracturing and faulting, as well as the occurrence of coarser deposits, on the western side of the area, make the location of faults less clear. The results show that gases migrate preferentially through zones of brittle deformation by advective processes, as suggested by the relatively high rate of migration needed to obtain anomalies of short-lived 222Rn in the soil pores. Furthermore, a geostatistical study of soil gas data was conducted to quantify the spatial domain of correlation and the gas-bearing properties of faults on the basis of shallow soil gas distribution (i.e., anisotropic behavior). The results provide a clear correlation between the shape and orientation of the anomalies and the different geometry of the faults recognized in the plain.

  4. Two-point versus multiple-point geostatistics: the ability of geostatistical methods to capture complex geobodies and their facies associations—an application to a channelized carbonate reservoir, southwest Iran

    Science.gov (United States)

    Hashemi, Seyyedhossein; Javaherian, Abdolrahim; Ataee-pour, Majid; Khoshdel, Hossein

    2014-12-01

    Facies models try to explain facies architectures which have a primary control on the subsurface heterogeneities and the fluid flow characteristics of a given reservoir. In the process of facies modeling, geostatistical methods are implemented to integrate different sources of data into a consistent model. The facies models should describe facies interactions; the shape and geometry of the geobodies as they occur in reality. Two distinct categories of geostatistical techniques are two-point and multiple-point (geo) statistics (MPS). In this study, both of the aforementioned categories were applied to generate facies models. A sequential indicator simulation (SIS) and a truncated Gaussian simulation (TGS) represented two-point geostatistical methods, and a single normal equation simulation (SNESIM) selected as an MPS simulation representative. The dataset from an extremely channelized carbonate reservoir located in southwest Iran was applied to these algorithms to analyze their performance in reproducing complex curvilinear geobodies. The SNESIM algorithm needs consistent training images (TI) in which all possible facies architectures that are present in the area are included. The TI model was founded on the data acquired from modern occurrences. These analogies delivered vital information about the possible channel geometries and facies classes that are typically present in those similar environments. The MPS results were conditioned to both soft and hard data. Soft facies probabilities were acquired from a neural network workflow. In this workflow, seismic-derived attributes were implemented as the input data. Furthermore, MPS realizations were conditioned to hard data to guarantee the exact positioning and continuity of the channel bodies. A geobody extraction workflow was implemented to extract the most certain parts of the channel bodies from the seismic data. These extracted parts of the channel bodies were applied to the simulation workflow as hard data. This

  5. Geostatistical Methods For Determination of Roughness, Topography, And Changes of Antarctic Ice Streams From SAR And Radar Altimeter Data

    Science.gov (United States)

    Herzfeld, Ute C.

    2002-01-01

    The central objective of this project has been the development of geostatistical methods fro mapping elevation and ice surface characteristics from satellite radar altimeter (RA) and Syntheitc Aperture Radar (SAR) data. The main results are an Atlas of elevation maps of Antarctica, from GEOSAT RA data and an Atlas from ERS-1 RA data, including a total of about 200 maps with 3 km grid resolution. Maps and digital terrain models are applied to monitor and study changes in Antarctic ice streams and glaciers, including Lambert Glacier/Amery Ice Shelf, Mertz and Ninnis Glaciers, Jutulstraumen Glacier, Fimbul Ice Shelf, Slessor Glacier, Williamson Glacier and others.

  6. Evaluation of geostatistics interpolators and deterministic of the daily reference evapotranspiration in the state of Espirito Santo = Avaliação de interpoladores geoestatísticos e determinísticos da evapotranspiração de referência diária para o estado do Espírito Santo

    Directory of Open Access Journals (Sweden)

    Giselle Sabadim Saraiva

    2017-03-01

    Full Text Available In the state of Espírito Santo it is notorious the importance of agriculture for the State economy, several crops have been irrigated due to irregular distribution of rainfall. The daily reference evapotranspiration (ETo is an important variable in irrigation management, making it possible to quantify the water demand of a culture and region. This study aimed to compare interpolation methods to the spatial distribution of daily ETo. The study included the state of Espírito Santo, Brazil, with a total area of 46,184.1 km2 . Fifteen automatic meteorological stations were selected as the basis for interpolation and ten for cross-validation. The daily data analyzed were from the period 2010-2012, using three methods of interpolation, employed: the Kriging geostatistical method and deterministic methods Distance Square Inverse (IQD and Spline Tensioned. Three sets of data were interpolated. The IQD interpolation presented the best performance for the variable among the three methods, presenting lower deviation and variation among the ETo values estimated by the Penman-Monteith method. The IQD interpolator showed, as a good method to estimate the daily reference evapotranspiration variable in places where do not have weather stations installed. The estimated values of ETo obtained by IQD interpolation method can be used with confidence in irrigation management. = No estado do Espírito Santo é notório o destaque da agricultura na sua economia, mas, devido a irregularidade na distribuição das chuvas, as culturas têm sido irrigadas, sendo assim, o manejo da irrigação se torna importante para a produção das culturas. A evapotranspiração de referência (ETo diária é uma variável importante no manejo da irrigação, possibilitando quantificar a demanda hídrica de uma cultura e região. Objetivou-se com este trabalho comparar métodos de interpolação visando à espacialização da ETo diária. A área de abrangência do estudo foi o

  7. Comparing the applicability of some geostatistical methods to predict the spatial distribution of topsoil Calcium Carbonate in part of farmland of Zanjan Province

    Science.gov (United States)

    Sarmadian, Fereydoon; Keshavarzi, Ali

    2010-05-01

    Most of soils in iran, were located in the arid and semi-arid regions and have high pH (more than 7) and high amount of calcium carbonate and this problem cause to their calcification.In calcareous soils, plant growing and production is difficult. Most part of this problem, in relation to high pH and high concentration of calcium ion that cause to fixation and unavailability of elements which were dependent to pH, especially Phosphorous and some micro nutrients such as Fe, Zn, Mn and Cu. Prediction of soil calcium carbonate in non-sampled areas and mapping the calcium carbonate variability in order to sustainable management of soil fertility is very important.So, this research was done with the aim of evaluation and analyzing spatial variability of topsoil calcium carbonate as an aspect of soil fertility and plant nutrition, comparing geostatistical methods such as kriging and co-kriging and mapping topsoil calcium carbonate. For geostatistical analyzing, sampling was done with stratified random method and soil samples from 0 to 15 cm depth were collected with auger within 23 locations.In co-kriging method, salinity data was used as auxiliary variable. For comparing and evaluation of geostatistical methods, cross validation were used by statistical parameters of RMSE. The results showed that co-kriging method has the highest correlation coefficient and less RMSE and has the higher accuracy than kriging method to prediction of calcium carbonate content in non-sampled areas.

  8. Analysis of dengue fever risk using geostatistics model in bone regency

    Science.gov (United States)

    Amran, Stang, Mallongi, Anwar

    2017-03-01

    This research aim is to analysis of dengue fever risk based on Geostatistics model in Bone Regency. Risk levels of dengue fever are denoted by parameter of Binomial distribution. Effect of temperature, rainfalls, elevation, and larvae abundance are investigated through Geostatistics model. Bayesian hierarchical method is used in estimation process. Using dengue fever data in eleven locations this research shows that temperature and rainfall have significant effect of dengue fever risk in Bone regency.

  9. Assessment of nitrate pollution in the Grand Morin aquifers (France): Combined use of geostatistics and physically based modeling

    Energy Technology Data Exchange (ETDEWEB)

    Flipo, Nicolas [Centre de Geosciences, UMR Sisyphe, ENSMP, 35 rue Saint-Honore, F-77305 Fontainebleau (France)]. E-mail: nicolas.flipo@ensmp.fr; Jeannee, Nicolas [Geovariances, 49 bis, avenue Franklin Roosevelt, F-77212 Avon (France); Poulin, Michel [Centre de Geosciences, UMR Sisyphe, ENSMP, 35 rue Saint-Honore, F-77305 Fontainebleau (France); Even, Stephanie [Centre de Geosciences, UMR Sisyphe, ENSMP, 35 rue Saint-Honore, F-77305 Fontainebleau (France); Ledoux, Emmanuel [Centre de Geosciences, UMR Sisyphe, ENSMP, 35 rue Saint-Honore, F-77305 Fontainebleau (France)

    2007-03-15

    The objective of this work is to combine several approaches to better understand nitrate fate in the Grand Morin aquifers (2700 km{sup 2}), part of the Seine basin. CAWAQS results from the coupling of the hydrogeological model NEWSAM with the hydrodynamic and biogeochemical model of river PROSE. CAWAQS is coupled with the agronomic model STICS in order to simulate nitrate migration in basins. First, kriging provides a satisfactory representation of aquifer nitrate contamination from local observations, to set initial conditions for the physically based model. Then associated confidence intervals, derived from data using geostatistics, are used to validate CAWAQS results. Results and evaluation obtained from the combination of these approaches are given (period 1977-1988). Then CAWAQS is used to simulate nitrate fate for a 20-year period (1977-1996). The mean nitrate concentrations increase in aquifers is 0.09 mgN L{sup -1} yr{sup -1}, resulting from an average infiltration flux of 3500 kgN.km{sup -2} yr{sup -1}. - Combined use of geostatistics and physically based modeling allows assessment of nitrate concentrations in aquifer systems.

  10. Assessment of nitrate pollution in the Grand Morin aquifers (France): Combined use of geostatistics and physically based modeling

    International Nuclear Information System (INIS)

    Flipo, Nicolas; Jeannee, Nicolas; Poulin, Michel; Even, Stephanie; Ledoux, Emmanuel

    2007-01-01

    The objective of this work is to combine several approaches to better understand nitrate fate in the Grand Morin aquifers (2700 km 2 ), part of the Seine basin. CAWAQS results from the coupling of the hydrogeological model NEWSAM with the hydrodynamic and biogeochemical model of river PROSE. CAWAQS is coupled with the agronomic model STICS in order to simulate nitrate migration in basins. First, kriging provides a satisfactory representation of aquifer nitrate contamination from local observations, to set initial conditions for the physically based model. Then associated confidence intervals, derived from data using geostatistics, are used to validate CAWAQS results. Results and evaluation obtained from the combination of these approaches are given (period 1977-1988). Then CAWAQS is used to simulate nitrate fate for a 20-year period (1977-1996). The mean nitrate concentrations increase in aquifers is 0.09 mgN L -1 yr -1 , resulting from an average infiltration flux of 3500 kgN.km -2 yr -1 . - Combined use of geostatistics and physically based modeling allows assessment of nitrate concentrations in aquifer systems

  11. Geostatistical Analysis of Mesoscale Spatial Variability and Error in SeaWiFS and MODIS/Aqua Global Ocean Color Data

    Science.gov (United States)

    Glover, David M.; Doney, Scott C.; Oestreich, William K.; Tullo, Alisdair W.

    2018-01-01

    Mesoscale (10-300 km, weeks to months) physical variability strongly modulates the structure and dynamics of planktonic marine ecosystems via both turbulent advection and environmental impacts upon biological rates. Using structure function analysis (geostatistics), we quantify the mesoscale biological signals within global 13 year SeaWiFS (1998-2010) and 8 year MODIS/Aqua (2003-2010) chlorophyll a ocean color data (Level-3, 9 km resolution). We present geographical distributions, seasonality, and interannual variability of key geostatistical parameters: unresolved variability or noise, resolved variability, and spatial range. Resolved variability is nearly identical for both instruments, indicating that geostatistical techniques isolate a robust measure of biophysical mesoscale variability largely independent of measurement platform. In contrast, unresolved variability in MODIS/Aqua is substantially lower than in SeaWiFS, especially in oligotrophic waters where previous analysis identified a problem for the SeaWiFS instrument likely due to sensor noise characteristics. Both records exhibit a statistically significant relationship between resolved mesoscale variability and the low-pass filtered chlorophyll field horizontal gradient magnitude, consistent with physical stirring acting on large-scale gradient as an important factor supporting observed mesoscale variability. Comparable horizontal length scales for variability are found from tracer-based scaling arguments and geostatistical decorrelation. Regional variations between these length scales may reflect scale dependence of biological mechanisms that also create variability directly at the mesoscale, for example, enhanced net phytoplankton growth in coastal and frontal upwelling and convective mixing regions. Global estimates of mesoscale biophysical variability provide an improved basis for evaluating higher resolution, coupled ecosystem-ocean general circulation models, and data assimilation.

  12. DEM-based delineation for improving geostatistical interpolation of rainfall in mountainous region of Central Himalayas, India

    Science.gov (United States)

    Kumari, Madhuri; Singh, Chander Kumar; Bakimchandra, Oinam; Basistha, Ashoke

    2017-10-01

    In mountainous region with heterogeneous topography, the geostatistical modeling of the rainfall using global data set may not confirm to the intrinsic hypothesis of stationarity. This study was focused on improving the precision of the interpolated rainfall maps by spatial stratification in complex terrain. Predictions of the normal annual rainfall data were carried out by ordinary kriging, universal kriging, and co-kriging, using 80-point observations in the Indian Himalayas extending over an area of 53,484 km2. A two-step spatial clustering approach is proposed. In the first step, the study area was delineated into two regions namely lowland and upland based on the elevation derived from the digital elevation model. The delineation was based on the natural break classification method. In the next step, the rainfall data was clustered into two groups based on its spatial location in lowland or upland. The terrain ruggedness index (TRI) was incorporated as a co-variable in co-kriging interpolation algorithm. The precision of the kriged and co-kriged maps was assessed by two accuracy measures, root mean square error and Chatfield's percent better. It was observed that the stratification of rainfall data resulted in 5-20 % of increase in the performance efficiency of interpolation methods. Co-kriging outperformed the kriging models at annual and seasonal scale. The result illustrates that the stratification of the study area improves the stationarity characteristic of the point data, thus enhancing the precision of the interpolated rainfall maps derived using geostatistical methods.

  13. Bayesian geostatistical modeling of leishmaniasis incidence in Brazil.

    Directory of Open Access Journals (Sweden)

    Dimitrios-Alexios Karagiannis-Voules

    Full Text Available BACKGROUND: Leishmaniasis is endemic in 98 countries with an estimated 350 million people at risk and approximately 2 million cases annually. Brazil is one of the most severely affected countries. METHODOLOGY: We applied Bayesian geostatistical negative binomial models to analyze reported incidence data of cutaneous and visceral leishmaniasis in Brazil covering a 10-year period (2001-2010. Particular emphasis was placed on spatial and temporal patterns. The models were fitted using integrated nested Laplace approximations to perform fast approximate Bayesian inference. Bayesian variable selection was employed to determine the most important climatic, environmental, and socioeconomic predictors of cutaneous and visceral leishmaniasis. PRINCIPAL FINDINGS: For both types of leishmaniasis, precipitation and socioeconomic proxies were identified as important risk factors. The predicted number of cases in 2010 were 30,189 (standard deviation [SD]: 7,676 for cutaneous leishmaniasis and 4,889 (SD: 288 for visceral leishmaniasis. Our risk maps predicted the highest numbers of infected people in the states of Minas Gerais and Pará for visceral and cutaneous leishmaniasis, respectively. CONCLUSIONS/SIGNIFICANCE: Our spatially explicit, high-resolution incidence maps identified priority areas where leishmaniasis control efforts should be targeted with the ultimate goal to reduce disease incidence.

  14. Bayesian Analysis of Geostatistical Models With an Auxiliary Lattice

    KAUST Repository

    Park, Jincheol

    2012-04-01

    The Gaussian geostatistical model has been widely used for modeling spatial data. However, this model suffers from a severe difficulty in computation: it requires users to invert a large covariance matrix. This is infeasible when the number of observations is large. In this article, we propose an auxiliary lattice-based approach for tackling this difficulty. By introducing an auxiliary lattice to the space of observations and defining a Gaussian Markov random field on the auxiliary lattice, our model completely avoids the requirement of matrix inversion. It is remarkable that the computational complexity of our method is only O(n), where n is the number of observations. Hence, our method can be applied to very large datasets with reasonable computational (CPU) times. The numerical results indicate that our model can approximate Gaussian random fields very well in terms of predictions, even for those with long correlation lengths. For real data examples, our model can generally outperform conventional Gaussian random field models in both prediction errors and CPU times. Supplemental materials for the article are available online. © 2012 American Statistical Association, Institute of Mathematical Statistics, and Interface Foundation of North America.

  15. Geostatistical analysis of morphometric features in the selected parts of the Sudetes (SW Poland)

    Science.gov (United States)

    Pawlowski, Lukasz; Szymanowski, Mariusz; Migon, Piotr

    2017-04-01

    Recent years have brought rapid development of quantitative techniques that are successfully applied in geomorphology. They open up new interpretation possibilities, even in seemingly very well recognized areas. In particular, we are talking about the geomorphometric and geostatistical techniques whose integration in Geographic Information Systems allows to look at the spatial pattern of landforms and process signatures from a new perspective. The morphology of the Sudetes, as of other mountain ranges in central Europe, is the result of protracted interaction of tectonic and surface processes, passive geological factors such as lithology and structure, and passage of time. This raises the question whether, and to which extent, these different controls and signals have resulted in similarities or differences in the morphometric structure of different parts within the same mountain range. In this paper we assume that geomorphic signals of various origins are expressed by a set of primary and secondary topographic attributes, which can be further analyzed as regional variables and modelled using geostatistical methods. Special attention is paid to variogram modelling. This method allows the identification of the spatial structure of the morphometric characteristics, its spatial scale and direction reflected in quantitative parameters of variograms (model functions, range, sill, nugget, anisotropy). This parameters for various areas are compared to find (dis-)similarities between different parts of the Sudetes. Thus, the main goals of the paper are: 1. To evaluate the usefulness of topographic attributes' variogram modelling for quantification of the spatial morphometric structure of mountain areas, on the example of medium-altitude, non-glaciated mountain terrain. 2. To compare different parts of the Sudetes to find similarities and differences between them and to interpret the findings through the examination of geology and geomorphology of the region. The analysis

  16. Time-lapse analysis of methane quantity in Mary Lee group of coal seams using filter-based multiple-point geostatistical simulation

    Science.gov (United States)

    Karacan, C. Özgen; Olea, Ricardo A.

    2013-01-01

    Coal seam degasification and its success are important for controlling methane, and thus for the health and safety of coal miners. During the course of degasification, properties of coal seams change. Thus, the changes in coal reservoir conditions and in-place gas content as well as methane emission potential into mines should be evaluated by examining time-dependent changes and the presence of major heterogeneities and geological discontinuities in the field. In this work, time-lapsed reservoir and fluid storage properties of the New Castle coal seam, Mary Lee/Blue Creek seam, and Jagger seam of Black Warrior Basin, Alabama, were determined from gas and water production history matching and production forecasting of vertical degasification wellbores. These properties were combined with isotherm and other important data to compute gas-in-place (GIP) and its change with time at borehole locations. Time-lapsed training images (TIs) of GIP and GIP difference corresponding to each coal and date were generated by using these point-wise data and Voronoi decomposition on the TI grid, which included faults as discontinuities for expansion of Voronoi regions. Filter-based multiple-point geostatistical simulations, which were preferred in this study due to anisotropies and discontinuities in the area, were used to predict time-lapsed GIP distributions within the study area. Performed simulations were used for mapping spatial time-lapsed methane quantities as well as their uncertainties within the study area.

  17. Accounting for regional background and population size in the detection of spatial clusters and outliers using geostatistical filtering and spatial neutral models: the case of lung cancer in Long Island, New York

    Directory of Open Access Journals (Sweden)

    Goovaerts Pierre

    2004-07-01

    Full Text Available Abstract Background Complete Spatial Randomness (CSR is the null hypothesis employed by many statistical tests for spatial pattern, such as local cluster or boundary analysis. CSR is however not a relevant null hypothesis for highly complex and organized systems such as those encountered in the environmental and health sciences in which underlying spatial pattern is present. This paper presents a geostatistical approach to filter the noise caused by spatially varying population size and to generate spatially correlated neutral models that account for regional background obtained by geostatistical smoothing of observed mortality rates. These neutral models were used in conjunction with the local Moran statistics to identify spatial clusters and outliers in the geographical distribution of male and female lung cancer in Nassau, Queens, and Suffolk counties, New York, USA. Results We developed a typology of neutral models that progressively relaxes the assumptions of null hypotheses, allowing for the presence of spatial autocorrelation, non-uniform risk, and incorporation of spatially heterogeneous population sizes. Incorporation of spatial autocorrelation led to fewer significant ZIP codes than found in previous studies, confirming earlier claims that CSR can lead to over-identification of the number of significant spatial clusters or outliers. Accounting for population size through geostatistical filtering increased the size of clusters while removing most of the spatial outliers. Integration of regional background into the neutral models yielded substantially different spatial clusters and outliers, leading to the identification of ZIP codes where SMR values significantly depart from their regional background. Conclusion The approach presented in this paper enables researchers to assess geographic relationships using appropriate null hypotheses that account for the background variation extant in real-world systems. In particular, this new

  18. Menses cup evaluation study.

    Science.gov (United States)

    Cheng, M; Kung, R; Hannah, M; Wilansky, D; Shime, J

    1995-09-01

    To determine whether the menses cup is well tolerated by menstruating women. Prospective descriptive clinical study. Normal human volunteers in an academic research environment. Fifty-one menstruating women recruited between June to December 1991. Each participant was provided with two menses cups and an instruction sheet. Baseline information, including age, occupation, martial status, parity, description of menstrual flow, and current method used to cope with menstrual flow was collected. Subjects were asked to describe their experience with the cup at 1-, 2-, 6-, and 12-month intervals. The proportion of women who found the cup acceptable. The cup was used by 51 subjects for a total of 159 cycles. Overall, 23 women (45%) found the cup an acceptable method for coping with menses. Among 29 (57%) women who used the cup for two or more cycles, 62% found it acceptable. The menses cup may be an acceptable method for some women for coping with menstrual flow.

  19. Delineating Facies Spatial Distribution by Integrating Ensemble Data Assimilation and Indicator Geostatistics with Level Set Transformation.

    Energy Technology Data Exchange (ETDEWEB)

    Hammond, Glenn Edward; Song, Xuehang; Ye, Ming; Dai, Zhenxue; Zachara, John; Chen, Xingyuan

    2017-03-01

    A new approach is developed to delineate the spatial distribution of discrete facies (geological units that have unique distributions of hydraulic, physical, and/or chemical properties) conditioned not only on direct data (measurements directly related to facies properties, e.g., grain size distribution obtained from borehole samples) but also on indirect data (observations indirectly related to facies distribution, e.g., hydraulic head and tracer concentration). Our method integrates for the first time ensemble data assimilation with traditional transition probability-based geostatistics. The concept of level set is introduced to build shape parameterization that allows transformation between discrete facies indicators and continuous random variables. The spatial structure of different facies is simulated by indicator models using conditioning points selected adaptively during the iterative process of data assimilation. To evaluate the new method, a two-dimensional semi-synthetic example is designed to estimate the spatial distribution and permeability of two distinct facies from transient head data induced by pumping tests. The example demonstrates that our new method adequately captures the spatial pattern of facies distribution by imposing spatial continuity through conditioning points. The new method also reproduces the overall response in hydraulic head field with better accuracy compared to data assimilation with no constraints on spatial continuity on facies.

  20. Large to intermediate-scale aquifer heterogeneity in fine-grain dominated alluvial fans (Cenozoic As Pontes Basin, northwestern Spain): insight based on three-dimensional geostatistical reconstruction

    Science.gov (United States)

    Falivene, O.; Cabrera, L.; Sáez, A.

    2007-08-01

    Facies reconstructions are used in hydrogeology to improve the interpretation of aquifer permeability distribution. In the absence of sufficient data to define the heterogeneity due to geological processes, uncertainties in the distribution of aquifer hydrofacies and characteristics may appear. Geometric and geostatistical methods are used to understand and model aquifer hydrofacies distribution, providing models to improve comprehension and development of aquifers. However, these models require some input statistical parameters that can be difficult to infer from the study site. A three-dimensional reconstruction of a kilometer scale fine-grain dominated Cenozoic alluvial fan derived from more than 200 continuously cored, closely spaced, and regularly distributed wells is presented. The facies distributions were reconstructed using a genetic stratigraphic subdivision and a deterministic geostatistical algorithm. The reconstruction is only slightly affected by variations in the geostatistical input parameters because of the high-density data set. Analysis of the reconstruction allowed identification in the proximal to medial alluvial fan zones of several laterally extensive sand bodies with relatively higher permeability; these sand bodies were quantified in terms of volume, mean thickness, maximum area, and maximum equivalent diameter. These quantifications provide trends and geological scenarios for input statistical parameters to model aquifer systems in similar alluvial fan depositional settings.

  1. TIPs Evaluation Project Prospective Study.

    Science.gov (United States)

    Melzer, Becky A.; Hubbard, Susan M.; Huang, Judy Y.

    2003-01-01

    Used an experimental design to examine four different approaches to disseminating Treatment Improvement Protocols to substance abuse professionals. Although results of this ongoing study are not yet available, this article describes the use of triangulation methodology in evaluation studies. (SLD)

  2. Determination of homogeneous zones for liming recommendations of black pepper using geostatistics

    Directory of Open Access Journals (Sweden)

    Ivoney Gontijo

    Full Text Available ABSTRACT Studies aimed at determining homogeneous zones and the spatial variability of soil characteristics may improve the efficiency of agricultural input applications. The purpose of this study was to determine homogeneous zones for liming applications and to characterize the spatial variability of characteristics related to soil acidity and productivity in an Oxisol cultivated with black pepper (Piper nigrum L.. This study was carried out in São Mateus, state of Espírito Santo, Brazil. The experimental site was 100 x 120 m. A grid with 126 sampling points was established. Three soil sub-samples were collected at each sampling point in the black pepper canopy areas, at a 0-0.20 m depth. Crop productivity was estimated by harvesting the three plants neighboring each sampling point. Descriptive statistics and geostatistical analyses were performed. Homogeneous management zones were defined based on map of liming needs. Mathematical models adjusted to semivariograms indicated that all of the studied variables exhibited spatial dependency. An analysis of the spatial variability together with the definition of homogeneous zones can be used to increase the efficiency of soil liming.

  3. Mapping mean annual and monthly river discharges: geostatistical developments for incorporating river network dependencies

    International Nuclear Information System (INIS)

    Sauquet, Eric

    2004-01-01

    Regional hydrology is one topic that shows real improvement in partly due to new statistical development and computation facilities. Nevertheless theoretical difficulties for mapping river regime characteristics or recover these features at un gauged location remain because of the nature of the variable under study: river flows are related to a specific area that is defined by the drainage basin, are spatially organised by the river network with upstream-downstream dependencies. Estimations of hydrological descriptors are required for studying links with ecological processes at different spatial scale, from local site where biological or/and water quality data are available to large scale for sustainable development purposes. This presentation aims at describing a method for runoff pattern along the main river network. The approach dedicated to mean annual runoff is based on geostatistical interpolation procedures to which a constraint of water budget has been added. Expansion in Empirical Orthogonal Function has been considered in combination with kriging for interpolating mean monthly discharges. The methodologies are implemented within a Geographical Information System and illustrated by two study cases (two large basins in France). River flow regime descriptors are estimated for basins of more than 50km 2 . Opportunities of collaboration with a partition of France into hydro-eco regions derived from geology and climate considerations is discussed. (Author)

  4. The geostatistical approach for structural and stratigraphic framework analysis of offshore NW Bonaparte Basin, Australia

    International Nuclear Information System (INIS)

    Wahid, Ali; Salim, Ahmed Mohamed Ahmed; Yusoff, Wan Ismail Wan; Gaafar, Gamal Ragab

    2016-01-01

    Geostatistics or statistical approach is based on the studies of temporal and spatial trend, which depend upon spatial relationships to model known information of variable(s) at unsampled locations. The statistical technique known as kriging was used for petrophycial and facies analysis, which help to assume spatial relationship to model the geological continuity between the known data and the unknown to produce a single best guess of the unknown. Kriging is also known as optimal interpolation technique, which facilitate to generate best linear unbiased estimation of each horizon. The idea is to construct a numerical model of the lithofacies and rock properties that honor available data and further integrate with interpreting seismic sections, techtonostratigraphy chart with sea level curve (short term) and regional tectonics of the study area to find the structural and stratigraphic growth history of the NW Bonaparte Basin. By using kriging technique the models were built which help to estimate different parameters like horizons, facies, and porosities in the study area. The variograms were used to determine for identification of spatial relationship between data which help to find the depositional history of the North West (NW) Bonaparte Basin

  5. The geostatistical approach for structural and stratigraphic framework analysis of offshore NW Bonaparte Basin, Australia

    Energy Technology Data Exchange (ETDEWEB)

    Wahid, Ali, E-mail: ali.wahid@live.com; Salim, Ahmed Mohamed Ahmed, E-mail: mohamed.salim@petronas.com.my; Yusoff, Wan Ismail Wan, E-mail: wanismail-wanyusoff@petronas.com.my [Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 32610 Tronoh, Perak (Malaysia); Gaafar, Gamal Ragab, E-mail: gaafargr@gmail.com [Petroleum Engineering Division, PETRONAS Carigali Sdn Bhd, Kuala Lumpur (Malaysia)

    2016-02-01

    Geostatistics or statistical approach is based on the studies of temporal and spatial trend, which depend upon spatial relationships to model known information of variable(s) at unsampled locations. The statistical technique known as kriging was used for petrophycial and facies analysis, which help to assume spatial relationship to model the geological continuity between the known data and the unknown to produce a single best guess of the unknown. Kriging is also known as optimal interpolation technique, which facilitate to generate best linear unbiased estimation of each horizon. The idea is to construct a numerical model of the lithofacies and rock properties that honor available data and further integrate with interpreting seismic sections, techtonostratigraphy chart with sea level curve (short term) and regional tectonics of the study area to find the structural and stratigraphic growth history of the NW Bonaparte Basin. By using kriging technique the models were built which help to estimate different parameters like horizons, facies, and porosities in the study area. The variograms were used to determine for identification of spatial relationship between data which help to find the depositional history of the North West (NW) Bonaparte Basin.

  6. The detection of thermophilous forest hotspots in Poland using geostatistical interpolation of plant richness

    Directory of Open Access Journals (Sweden)

    Marcin Kiedrzyński

    2014-07-01

    Full Text Available Attempts to study biodiversity hotspots on a regional scale should combine compositional and functionalist criteria. The detection of hotspots in this study uses one ecologically similar group of high conservation value species as hotspot indicators, as well as focal habitat indicators, to detect the distribution of suitable environmental conditions. The method is assessed with reference to thermophilous forests in Poland – key habitats for many rare and relict species. Twenty-six high conservation priority species were used as hotspot indicators, and ten plant taxa characteristic of the Quercetalia pubescenti-petraeae phytosociological order were used as focal habitat indicators. Species distribution data was based on a 10 × 10 km grid. The number of species per grid square was interpolated by the ordinary kriging geostatistical method. Our analysis largely determined the distribution of areas with concentration of thermophilous forest flora, but also regional disjunctions and geographical barriers. Indicator species richness can be interpreted as a reflection of the actual state of habitat conditions. It can also be used to determine the location of potential species refugia and possible past and future migration routes.

  7. Geostatistical Approach to Find ‘Hotspots’ Where Biodiversity is at Risk in a Transition Country

    Directory of Open Access Journals (Sweden)

    Petrişor Alexandru-Ionuţ

    2014-10-01

    Full Text Available Global change‟ is a relatively recent concept, related to the energy - land use - climate change nexus, and designated to include all changes produced by the human species and the consequences of its activities over natural ecological complexes and biodiversity. The joint effects of these drivers of change are particularly relevant to understanding the changes of biodiversity. This study overlaps results of previous studies developed in Romania to find, explain and predict potential threats on biodiversity, including the effects of very high temperatures and low precipitations, urban sprawl and deforestation in order to identify „hotspots‟ of high risk for the loss of biodiversity using geostatistical tools. The results found two hotspots, one in the center and the other one in the south, and show that the area affected by three factors simultaneously represents 0.2% of the national territory, while paired effects cover 4% of it. The methodological advantage of this approach is its capacity to pinpoint hotspots with practical relevance. Nevertheless, its generalizing character impairs its use at the local scale..

  8. The Possibilities and Limitations of Geostatistical Methods in Real Estate Market Analyses

    Directory of Open Access Journals (Sweden)

    Cellmer Radosław

    2014-10-01

    Full Text Available In the traditional approach, geostatistical modeling involves analyses of the spatial structure of regionalized data, as well as estimations and simulations that rely on kriging methods. Geostatistical methods can complement traditional statistical models of property transaction prices, and when combined with those models, they offer a comprehensive tool for spatial analysis that is used in the process of developing land value maps. Transaction prices are characterized by mutual spatial correlations and can be considered as regionalized variables. They can also be regarded as random variables that have a local character and a specific probability distribution.

  9. EIA and EINP. Evaluation study

    International Nuclear Information System (INIS)

    Lande, R.W.I. van der; De Vries, E.F.

    2001-01-01

    The evaluation study on the title subjects concerns two subsidy tools in the Netherlands: the Energy Investment Rebate (EIA, abbreviated in Dutch) and the Subsidy for Energy in the non-profit sector and other special sectors (EINP, abbreviated in Dutch). The central question in the evaluation was to what extent did the EIA and EINP contribute to the original policy targets and at what costs. The evaluation has been carried out by means of a desk study, interviews, and an analysis of bottlenecks and possible solutions. [nl

  10. Geostatistical interpolation of daily rainfall at catchment scale: the use of several variogram models in the Ourthe and Ambleve catchments, Belgium

    Directory of Open Access Journals (Sweden)

    S. Ly

    2011-07-01

    Full Text Available Spatial interpolation of precipitation data is of great importance for hydrological modelling. Geostatistical methods (kriging are widely applied in spatial interpolation from point measurement to continuous surfaces. The first step in kriging computation is the semi-variogram modelling which usually used only one variogram model for all-moment data. The objective of this paper was to develop different algorithms of spatial interpolation for daily rainfall on 1 km2 regular grids in the catchment area and to compare the results of geostatistical and deterministic approaches. This study leaned on 30-yr daily rainfall data of 70 raingages in the hilly landscape of the Ourthe and Ambleve catchments in Belgium (2908 km2. This area lies between 35 and 693 m in elevation and consists of river networks, which are tributaries of the Meuse River. For geostatistical algorithms, seven semi-variogram models (logarithmic, power, exponential, Gaussian, rational quadratic, spherical and penta-spherical were fitted to daily sample semi-variogram on a daily basis. These seven variogram models were also adopted to avoid negative interpolated rainfall. The elevation, extracted from a digital elevation model, was incorporated into multivariate geostatistics. Seven validation raingages and cross validation were used to compare the interpolation performance of these algorithms applied to different densities of raingages. We found that between the seven variogram models used, the Gaussian model was the most frequently best fit. Using seven variogram models can avoid negative daily rainfall in ordinary kriging. The negative estimates of kriging were observed for convective more than stratiform rain. The performance of the different methods varied slightly according to the density of raingages, particularly between 8 and 70 raingages but it was much different for interpolation using 4 raingages. Spatial interpolation with the geostatistical and

  11. Geostatistical methods in the assessment of the spatial variability of the quality of river water

    Science.gov (United States)

    Krasowska, Małgorzata; Banaszuk, Piotr

    2017-11-01

    The research was conducted in the agricultural catchment in north-eastern Poland. The aim of this study was to check how geostatistical analysis can be useful for the detection zones and forms of supply stream by water from different sources. The work was included the implementation of hydrochemical profiles. These profiles were made by measuring the electrical conductivity (EC) values and temperature along the river. On the basis of these results, the authors calculated the coefficient of Moran I and performed semivariogram and found that the EC values are correlated on a stretch of about 140 m. This means that the spatial correlation between samples of water in the stream is readable over a distance of about 140 meters. Therefore it is believed that the degree of water mineralization on this section is shaped by water entering the river channel migration in different ways: through tributaries, leachate drainage and surface runoff. In the case of the analyzed catchment, the potential sources of pollution were drainage systems. Therefore, the spatial analysis allowed the identification pollution sources in a catchment, especially in drained agricultural catchments.

  12. A Resampling-Based Stochastic Approximation Method for Analysis of Large Geostatistical Data

    KAUST Repository

    Liang, Faming

    2013-03-01

    The Gaussian geostatistical model has been widely used in modeling of spatial data. However, it is challenging to computationally implement this method because it requires the inversion of a large covariance matrix, particularly when there is a large number of observations. This article proposes a resampling-based stochastic approximation method to address this challenge. At each iteration of the proposed method, a small subsample is drawn from the full dataset, and then the current estimate of the parameters is updated accordingly under the framework of stochastic approximation. Since the proposed method makes use of only a small proportion of the data at each iteration, it avoids inverting large covariance matrices and thus is scalable to large datasets. The proposed method also leads to a general parameter estimation approach, maximum mean log-likelihood estimation, which includes the popular maximum (log)-likelihood estimation (MLE) approach as a special case and is expected to play an important role in analyzing large datasets. Under mild conditions, it is shown that the estimator resulting from the proposed method converges in probability to a set of parameter values of equivalent Gaussian probability measures, and that the estimator is asymptotically normally distributed. To the best of the authors\\' knowledge, the present study is the first one on asymptotic normality under infill asymptotics for general covariance functions. The proposed method is illustrated with large datasets, both simulated and real. Supplementary materials for this article are available online. © 2013 American Statistical Association.

  13. Application of Geostatistical Methods and Machine Learning for spatio-temporal Earthquake Cluster Analysis

    Science.gov (United States)

    Schaefer, A. M.; Daniell, J. E.; Wenzel, F.

    2014-12-01

    Earthquake clustering tends to be an increasingly important part of general earthquake research especially in terms of seismic hazard assessment and earthquake forecasting and prediction approaches. The distinct identification and definition of foreshocks, aftershocks, mainshocks and secondary mainshocks is taken into account using a point based spatio-temporal clustering algorithm originating from the field of classic machine learning. This can be further applied for declustering purposes to separate background seismicity from triggered seismicity. The results are interpreted and processed to assemble 3D-(x,y,t) earthquake clustering maps which are based on smoothed seismicity records in space and time. In addition, multi-dimensional Gaussian functions are used to capture clustering parameters for spatial distribution and dominant orientations. Clusters are further processed using methodologies originating from geostatistics, which have been mostly applied and developed in mining projects during the last decades. A 2.5D variogram analysis is applied to identify spatio-temporal homogeneity in terms of earthquake density and energy output. The results are mitigated using Kriging to provide an accurate mapping solution for clustering features. As a case study, seismic data of New Zealand and the United States is used, covering events since the 1950s, from which an earthquake cluster catalogue is assembled for most of the major events, including a detailed analysis of the Landers and Christchurch sequences.

  14. A geostatistical approach to data harmonization - Application to radioactivity exposure data

    Science.gov (United States)

    Baume, O.; Skøien, J. O.; Heuvelink, G. B. M.; Pebesma, E. J.; Melles, S. J.

    2011-06-01

    Environmental issues such as air, groundwater pollution and climate change are frequently studied at spatial scales that cross boundaries between political and administrative regions. It is common for different administrations to employ different data collection methods. If these differences are not taken into account in spatial interpolation procedures then biases may appear and cause unrealistic results. The resulting maps may show misleading patterns and lead to wrong interpretations. Also, errors will propagate when these maps are used as input to environmental process models. In this paper we present and apply a geostatistical model that generalizes the universal kriging model such that it can handle heterogeneous data sources. The associated best linear unbiased estimation and prediction (BLUE and BLUP) equations are presented and it is shown that these lead to harmonized maps from which estimated biases are removed. The methodology is illustrated with an example of country bias removal in a radioactivity exposure assessment for four European countries. The application also addresses multicollinearity problems in data harmonization, which arise when both artificial bias factors and natural drifts are present and cannot easily be distinguished. Solutions for handling multicollinearity are suggested and directions for further investigations proposed.

  15. A Bayesian spatio-temporal geostatistical model with an auxiliary lattice for large datasets

    KAUST Repository

    Xu, Ganggang

    2015-01-01

    When spatio-temporal datasets are large, the computational burden can lead to failures in the implementation of traditional geostatistical tools. In this paper, we propose a computationally efficient Bayesian hierarchical spatio-temporal model in which the spatial dependence is approximated by a Gaussian Markov random field (GMRF) while the temporal correlation is described using a vector autoregressive model. By introducing an auxiliary lattice on the spatial region of interest, the proposed method is not only able to handle irregularly spaced observations in the spatial domain, but it is also able to bypass the missing data problem in a spatio-temporal process. Because the computational complexity of the proposed Markov chain Monte Carlo algorithm is of the order O(n) with n the total number of observations in space and time, our method can be used to handle very large spatio-temporal datasets with reasonable CPU times. The performance of the proposed model is illustrated using simulation studies and a dataset of precipitation data from the coterminous United States.

  16. Definition of radon prone areas in Friuli Venezia Giulia region, Italy, using geostatistical tools.

    Science.gov (United States)

    Cafaro, C; Bossew, P; Giovani, C; Garavaglia, M

    2014-12-01

    Studying the geographical distribution of indoor radon concentration, using geostatistical interpolation methods, has become common for predicting and estimating the risk to the population. Here we analyse the case of Friuli Venezia Giulia (FVG), the north easternmost region of Italy. Mean value and standard deviation are, respectively, 153 Bq/m(3) and 183 Bq/m(3). The geometric mean value is 100 Bq/m(3). Spatial datasets of indoor radon concentrations are usually affected by clustering and apparent non-stationarity issues, which can eventually yield arguable results. The clustering of the present dataset seems to be non preferential. Therefore the areal estimations are not expected to be affected. Conversely, nothing can be said on the non stationarity issues and its effects. After discussing the correlation of geology with indoor radon concentration It appears they are created by the same geologic features influencing the mean and median values, and can't be eliminated via a map-based approach. To tackle these problems, in this work we deal with multiple definitions of RPA, but only in quaternary areas of FVG, using extensive simulation techniques. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Batch orographic interpolation of monthly precipitation based on free-of-charge geostatistical tools

    Science.gov (United States)

    Ledvinka, Ondrej

    2017-11-01

    The effects of possible climate change on water resources in prescribed areas (e.g. river basins) are intensively studied in hydrology. These resources are highly dependent on precipitation totals. When focusing on long-term changes in climate variables, one has to rely on station measurements. However, hydrologists need the information on spatial distribution of precipitation over the areas. For this purpose, the spatial interpolation techniques must be employed. In Czechia, where the addition of elevation co-variables proved to be a good choice, several GIS tools exist that are able to produce time series necessary for climate change analyses. Nevertheless, these tools are exclusively based on commercial software and there is a lack of free-of-charge tools that could be used by everyone. Here, selected free-of-charge geostatistical tools were utilized in order to produce monthly precipitation time series representing six river basins in the Ore Mountains located in NW Bohemia, Czechia and SE Saxony, Germany. The produced series span from January 1961 to December 2012. Rain-gauge data from both Czechia and Germany were used. The universal kriging technique was employed where a multiple linear regression (based on elevation and coordinates) residuals were interpolated. The final time series seem to be homogeneous.

  18. Integrating address geocoding, land use regression, and spatiotemporal geostatistical estimation for groundwater tetrachloroethylene.

    Science.gov (United States)

    Messier, Kyle P; Akita, Yasuyuki; Serre, Marc L

    2012-03-06

    Geographic information systems (GIS) based techniques are cost-effective and efficient methods used by state agencies and epidemiology researchers for estimating concentration and exposure. However, budget limitations have made statewide assessments of contamination difficult, especially in groundwater media. Many studies have implemented address geocoding, land use regression, and geostatistics independently, but this is the first to examine the benefits of integrating these GIS techniques to address the need of statewide exposure assessments. A novel framework for concentration exposure is introduced that integrates address geocoding, land use regression (LUR), below detect data modeling, and Bayesian Maximum Entropy (BME). A LUR model was developed for tetrachloroethylene that accounts for point sources and flow direction. We then integrate the LUR model into the BME method as a mean trend while also modeling below detects data as a truncated Gaussian probability distribution function. We increase available PCE data 4.7 times from previously available databases through multistage geocoding. The LUR model shows significant influence of dry cleaners at short ranges. The integration of the LUR model as mean trend in BME results in a 7.5% decrease in cross validation mean square error compared to BME with a constant mean trend.

  19. Real-time reservoir geological model updating using the hybrid EnKF and geostatistical technique

    Energy Technology Data Exchange (ETDEWEB)

    Li, H.; Chen, S.; Yang, D. [Regina Univ., SK (Canada). Petroleum Technology Research Centre

    2008-07-01

    Reservoir simulation plays an important role in modern reservoir management. Multiple geological models are needed in order to analyze the uncertainty of a given reservoir development scenario. Ideally, dynamic data should be incorporated into a reservoir geological model. This can be done by using history matching and tuning the model to match the past performance of reservoir history. This study proposed an assisted history matching technique to accelerate and improve the matching process. The Ensemble Kalman Filter (EnKF) technique, which is an efficient assisted history matching method, was integrated with a conditional geostatistical simulation technique to dynamically update reservoir geological models. The updated models were constrained to dynamic data, such as reservoir pressure and fluid saturations, and approaches geologically realistic at each time step by using the EnKF technique. The new technique was successfully applied in a heterogeneous synthetic reservoir. The uncertainty of the reservoir characterization was significantly reduced. More accurate forecasts were obtained from the updated models. 3 refs., 2 figs.

  20. Soil Moisture Mapping in an Arid Area Using a Land Unit Area (LUA Sampling Approach and Geostatistical Interpolation Techniques

    Directory of Open Access Journals (Sweden)

    Saeid Gharechelou

    2016-03-01

    Full Text Available Soil moisture (SM plays a key role in many environmental processes and has a high spatial and temporal variability. Collecting sample SM data through field surveys (e.g., for validation of remote sensing-derived products can be very expensive and time consuming if a study area is large, and producing accurate SM maps from the sample point data is a difficult task as well. In this study, geospatial processing techniques are used to combine several geo-environmental layers relevant to SM (soil, geology, rainfall, land cover, etc. into a land unit area (LUA map, which delineates regions with relatively homogeneous geological/geomorphological, land use/land cover, and climate characteristics. This LUA map is used to guide the collection of sample SM data in the field, and the field data is finally spatially interpolated to create a wall-to-wall map of SM in the study area (Garmsar, Iran. The main goal of this research is to create a SM map in an arid area, using a land unit area (LUA approach to obtain the most appropriate sample locations for collecting SM field data. Several environmental GIS layers, which have an impact on SM, were combined to generate a LUA map, and then field surveying was done in each class of the LUA map. A SM map was produced based on LUA, remote sensing data indexes, and spatial interpolation of the field survey sample data. The several interpolation methods (inverse distance weighting, kriging, and co-kriging were evaluated for generating SM maps from the sample data. The produced maps were compared to each other and validated using ground truth data. The results show that the LUA approach is a reasonable method to create the homogenous field to introduce a representative sample for field soil surveying. The geostatistical SM map achieved adequate accuracy; however, trend analysis and distribution of the soil sample point locations within the LUA types should be further investigated to achieve even better results. Co

  1. A novel geotechnical/geostatistical approach for exploration and production of natural gas from multiple geologic strata, Phase 1

    Energy Technology Data Exchange (ETDEWEB)

    Overbey, W.K. Jr.; Reeves, T.K.; Salamy, S.P.; Locke, C.D.; Johnson, H.R.; Brunk, R.; Hawkins, L. (BDM Engineering Services Co., Morgantown, WV (United States))

    1991-05-01

    This research program has been designed to develop and verify a unique geostatistical approach for finding natural gas resources. The project has been conducted by Beckley College, Inc., and BDM Engineering Services Company (BDMESC) under contract to the US Department of Energy (DOE), Morgantown Energy Technology Center (METC). This section, Volume II, contains a detailed discussion of the methodology used and the geological and production information collected and analyzed for this study. A companion document, Volume 1, provides an overview of the program, technique and results of the study. In combination, Volumes I and II cover the completion of the research undertaken under Phase I of this DOE project, which included the identification of five high-potential sites for natural gas production on the Eccles Quadrangle, Raleigh County, West Virginia. Each of these sites was selected for its excellent potential for gas production from both relatively shallow coalbeds and the deeper, conventional reservoir formations.

  2. A spatiotemporal geostatistical hurdle model approach for short-term deforestation prediction

    NARCIS (Netherlands)

    Ribeiro Sales, Marcio; Bruin, De Sytze; Herold, Martin; Kyriakidis, Phaedon; Souza, Carlos

    2017-01-01

    This paper introduces and tests a geostatistical spatiotemporal hurdle approach for predicting the spatial distribution of future deforestation (one to three years ahead in time). The method accounts for neighborhood effects by modeling the auto-correlation of occurrence and intensity of

  3. Confronting uncertainty in model-based geostatistics using Markov Chain Monte Carlo simulation

    NARCIS (Netherlands)

    Minasny, B.; Vrugt, J.A.; McBratney, A.B.

    2011-01-01

    This paper demonstrates for the first time the use of Markov Chain Monte Carlo (MCMC) simulation for parameter inference in model-based soil geostatistics. We implemented the recently developed DiffeRential Evolution Adaptive Metropolis (DREAM) algorithm to jointly summarize the posterior

  4. Combining Geostatistics with Moran’s I Analysis for Mapping Soil Heavy Metals in Beijing, China

    Directory of Open Access Journals (Sweden)

    Bao-Guo Li

    2012-03-01

    Full Text Available Production of high quality interpolation maps of heavy metals is important for risk assessment of environmental pollution. In this paper, the spatial correlation characteristics information obtained from Moran’s I analysis was used to supplement the traditional geostatistics. According to Moran’s I analysis, four characteristics distances were obtained and used as the active lag distance to calculate the semivariance. Validation of the optimality of semivariance demonstrated that using the two distances where the Moran’s I and the standardized Moran’s I, Z(I reached a maximum as the active lag distance can improve the fitting accuracy of semivariance. Then, spatial interpolation was produced based on the two distances and their nested model. The comparative analysis of estimation accuracy and the measured and predicted pollution status showed that the method combining geostatistics with Moran’s I analysis was better than traditional geostatistics. Thus, Moran’s I analysis is a useful complement for geostatistics to improve the spatial interpolation accuracy of heavy metals.

  5. Introduction to This Special Issue on Geostatistics and Geospatial Techniques in Remote Sensing

    Science.gov (United States)

    Atkinson, Peter; Quattrochi, Dale A.; Goodman, H. Michael (Technical Monitor)

    2000-01-01

    The germination of this special Computers & Geosciences (C&G) issue began at the Royal Geographical Society (with the Institute of British Geographers) (RGS-IBG) annual meeting in January 1997 held at the University of Exeter, UK. The snow and cold of the English winter were tempered greatly by warm and cordial discussion of how to stimulate and enhance cooperation on geostatistical and geospatial research in remote sensing 'across the big pond' between UK and US researchers. It was decided that one way forward would be to hold parallel sessions in 1998 on geostatistical and geospatial research in remote sensing at appropriate venues in both the UK and the US. Selected papers given at these sessions would be published as special issues of C&G on the UK side and Photogrammetric Engineering and Remote Sensing (PE&RS) on the US side. These issues would highlight the commonality in research on geostatistical and geospatial research in remote sensing on both sides of the Atlantic Ocean. As a consequence, a session on "Geostatistics and Geospatial Techniques for Remote Sensing of Land Surface Processes" was held at the RGS-IBG annual meeting in Guildford, Surrey, UK in January 1998, organized by the Modeling and Advanced Techniques Special Interest Group (MAT SIG) of the Remote Sensing Society (RSS). A similar session was held at the Association of American Geographers (AAG) annual meeting in Boston, Massachusetts in March 1998, sponsored by the AAG's Remote Sensing Specialty Group (RSSG). The 10 papers that make up this issue of C&G, comprise 7 papers from the UK and 3 papers from the LIS. We are both co-editors of each of the journal special issues, with the lead editor of each journal issue being from their respective side of the Atlantic. The special issue of PE&RS (vol. 65) that constitutes the other half of this co-edited journal series was published in early 1999, comprising 6 papers by US authors. We are indebted to the International Association for Mathematical

  6. Modeling spatial variability of sand-lenses in clay till settings using transition probability and multiple-point geostatistics

    DEFF Research Database (Denmark)

    Kessler, Timo Christian; Nilsson, Bertel; Klint, Knud Erik

    2010-01-01

    of sand-lenses in clay till. Sand-lenses mainly account for horizontal transport and are prioritised in this study. Based on field observations, the distribution has been modeled using two different geostatistical approaches. One method uses a Markov chain model calculating the transition probabilities......The construction of detailed geological models for heterogeneous settings such as clay till is important to describe transport processes, particularly with regard to potential contamination pathways. In low-permeability clay matrices transport is controlled by diffusion, but fractures and sand......-lenses facilitate local advective flow. In glacial settings these geological features occur at diverse extent, geometry, degree of deformation, and spatial distribution. The high level of heterogeneity requires extensive data collection, respectively detailed geological mapping. However, when characterising...

  7. Improve ground-level PM2.5concentration mapping using a random forests-based geostatistical approach.

    Science.gov (United States)

    Liu, Ying; Cao, Guofeng; Zhao, Naizhuo; Mulligan, Kevin; Ye, Xinyue

    2018-04-01

    Accurate measurements of ground-level PM 2.5 (particulate matter with aerodynamic diameters equal to or less than 2.5 μm) concentrations are critically important to human and environmental health studies. In this regard, satellite-derived gridded PM 2.5 datasets, particularly those datasets derived from chemical transport models (CTM), have demonstrated unique attractiveness in terms of their geographic and temporal coverage. The CTM-based approaches, however, often yield results with a coarse spatial resolution (typically at 0.1° of spatial resolution) and tend to ignore or simplify the impact of geographic and socioeconomic factors on PM 2.5 concentrations. In this study, with a focus on the long-term PM 2.5 distribution in the contiguous United States, we adopt a random forests-based geostatistical (regression kriging) approach to improve one of the most commonly used satellite-derived, gridded PM 2.5 datasets with a refined spatial resolution (0.01°) and enhanced accuracy. By combining the random forests machine learning method and the kriging family of methods, the geostatistical approach effectively integrates ground-based PM 2.5 measurements and related geographic variables while accounting for the non-linear interactions and the complex spatial dependence. The accuracy and advantages of the proposed approach are demonstrated by comparing the results with existing PM 2.5 datasets. This manuscript also highlights the effectiveness of the geographical variables in long-term PM 2.5 mapping, including brightness of nighttime lights, normalized difference vegetation index and elevation, and discusses the contribution of each of these variables to the spatial distribution of PM 2.5 concentrations. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Geostatistics and multivariate analysis as a tool to characterize volcaniclastic deposits: Application to Nevado de Toluca volcano, Mexico

    Science.gov (United States)

    Bellotti, F.; Capra, L.; Sarocchi, D.; D'Antonio, M.

    2010-03-01

    Grain size analysis of volcaniclastic deposits is mainly used to study flow transport and depositional processes, in most cases by comparing some statistical parameters and how they change with distance from the source. In this work the geospatial and multivariate analyses are presented as a strong adaptable geostatistical tool applied to volcaniclastic deposits in order to provide an effective and relatively simple methodology for texture description, deposit discrimination and interpretation of depositional processes. We choose the case of Nevado de Toluca volcano (Mexico) due to existing knowledge of its geological evolution, stratigraphic succession and spatial distribution of volcaniclastic units. Grain size analyses and frequency distribution curves have been carried out to characterize and compare the 28-ka block-and-ash flow deposit associated to a dome destruction episode, and the El Morral debris avalanche deposit originated from the collapse of the south-eastern sector of the volcano. The geostatistical interpolation of sedimentological data allows to realize bidimensional maps draped over the volcano topography, showing the granulometric distribution, sorting and fine material concentration into the whole deposit with respect to topographic changes. In this way, it is possible to analyze a continuous surface of the grain size distribution of volcaniclastic deposits and better understand flow transport processes. The application of multivariate statistic analysis (discriminant function) indicates that this methodology could be useful in discriminating deposits with different origin or different depositional lithofacies within the same deposit. The proposed methodology could be an interesting approach to sustain more classical analysis of volcaniclastic deposits, especially where a clear field classification appears problematic because of a homogeneous texture of the deposits or their scarce and discontinuous outcrops. Our study is an example of the

  9. Geostatistical modeling of the spatial distribution of sediment oxygen demand within a Coastal Plain blackwater watershed.

    Science.gov (United States)

    Todd, M Jason; Lowrance, R Richard; Goovaerts, Pierre; Vellidis, George; Pringle, Catherine M

    2010-10-15

    Blackwater streams are found throughout the Coastal Plain of the southeastern United States and are characterized by a series of instream floodplain swamps that play a critical role in determining the water quality of these systems. Within the state of Georgia, many of these streams are listed in violation of the state's dissolved oxygen (DO) standard. Previous work has shown that sediment oxygen demand (SOD) is elevated in instream floodplain swamps and due to these areas of intense oxygen demand, these locations play a major role in determining the oxygen balance of the watershed as a whole. This work also showed SOD rates to be positively correlated with the concentration of total organic carbon. This study builds on previous work by using geostatistics and Sequential Gaussian Simulation to investigate the patchiness and distribution of total organic carbon (TOC) at the reach scale. This was achieved by interpolating TOC observations and simulated SOD rates based on a linear regression. Additionally, this study identifies areas within the stream system prone to high SOD at representative 3rd and 5th order locations. Results show that SOD was spatially correlated with the differences in distribution of TOC at both locations and that these differences in distribution are likely a result of the differing hydrologic regime and watershed position. Mapping of floodplain soils at the watershed scale shows that areas of organic sediment are widespread and become more prevalent in higher order streams. DO dynamics within blackwater systems are a complicated mix of natural and anthropogenic influences, but this paper illustrates the importance of instream swamps in enhancing SOD at the watershed scale. Moreover, our study illustrates the influence of instream swamps on oxygen demand while providing support that many of these systems are naturally low in DO.

  10. Spatially explicit burden estimates of malaria in Tanzania: bayesian geostatistical modeling of the malaria indicator survey data.

    Directory of Open Access Journals (Sweden)

    Laura Gosoniu

    Full Text Available A national HIV/AIDS and malaria parasitological survey was carried out in Tanzania in 2007-2008. In this study the parasitological data were analyzed: i to identify climatic/environmental, socio-economic and interventions factors associated with child malaria risk and ii to produce a contemporary, high spatial resolution parasitaemia risk map of the country. Bayesian geostatistical models were fitted to assess the association between parasitaemia risk and its determinants. bayesian kriging was employed to predict malaria risk at unsampled locations across Tanzania and to obtain the uncertainty associated with the predictions. Markov chain Monte Carlo (MCMC simulation methods were employed for model fit and prediction. Parasitaemia risk estimates were linked to population data and the number of infected children at province level was calculated. Model validation indicated a high predictive ability of the geostatistical model, with 60.00% of the test locations within the 95% credible interval. The results indicate that older children are significantly more likely to test positive for malaria compared with younger children and living in urban areas and better-off households reduces the risk of infection. However, none of the environmental and climatic proxies or the intervention measures were significantly associated with the risk of parasitaemia. Low levels of malaria prevalence were estimated for Zanzibar island. The population-adjusted prevalence ranges from 0.29% in Kaskazini province (Zanzibar island to 18.65% in Mtwara region. The pattern of predicted malaria risk is similar with the previous maps based on historical data, although the estimates are lower. The predicted maps could be used by decision-makers to allocate resources and target interventions in the regions with highest burden of malaria in order to reduce the disease transmission in the country.

  11. Comparison of smoothness-constrained and geostatistically based cross-borehole electrical resistivity tomography for characterization of solute tracer plumes

    Directory of Open Access Journals (Sweden)

    Andreas Englert

    2016-10-01

    Full Text Available Experiments using electrical resistivity tomography (ERT have shown promising results in reducing the uncertainty of solute plume characteristics related to estimates based on the analysis of local point measurements only. To explore the similarities and differences between two cross-borehole ERT inversion approaches for characterizing salt tracer plumes, namely the classical smoothness-constrained inversion and a geostatistically based approach, we performed two-dimensional synthetic experiments. Simplifying assumptions about the solute transport model and the electrical forward and inverse model allowed us to study the sensitivity of the ERT inversion approaches towards a variety of basic conditions, including the number of boreholes, measurement schemes, contrast between the plume and background electrical conductivity, use of a priori knowledge, and point conditioning. The results show that geostatistically based and smoothness-constrained inversions of electrical resistance data yield plume characteristics of similar quality, which can be further improved when point measurements are incorporated and advantageous measurement schemes are chosen. As expected, an increased number of boreholes included in the ERT measurement layout can highly improve the quality of inferred plume characteristics, while in this case the benefits of point conditioning and advantageous measurement schemes diminish. Both ERT inversion approaches are similarly sensitive to the noise level of the data and the contrast between the solute plume and background electrical conductivity, and robust with regard to biased input parameters, such as mean concentration, variance, and correlation length of the plume. Although sophisticated inversion schemes have recently become available, in which flow and transport as well as electrical forward models are coupled, these schemes effectively rely on a relatively simple geometrical parameterization of the hydrogeological model

  12. Interannual Changes in Biomass Affect the Spatial Aggregations of Anchovy and Sardine as Evidenced by Geostatistical and Spatial Indicators.

    Directory of Open Access Journals (Sweden)

    Marco Barra

    Full Text Available Geostatistical techniques were applied and a series of spatial indicators were calculated (occupation, aggregation, location, dispersion, spatial autocorrelation and overlap to characterize the spatial distributions of European anchovy and sardine during summer. Two ecosystems were compared for this purpose, both located in the Mediterranean Sea: the Strait of Sicily (upwelling area and the North Aegean Sea (continental shelf area, influenced by freshwater. Although the biomass of anchovy and sardine presented high interannual variability in both areas, the location of the centres of gravity and the main spatial patches of their populations were very similar between years. The size of the patches representing the dominant part of the abundance (80% was mostly ecosystem- and species-specific. Occupation (area of presence appears to be shaped by the extent of suitable habitats in each ecosystem whereas aggregation patterns (how the populations are distributed within the area of presence were species-specific and related to levels of population biomass. In the upwelling area, both species showed consistently higher occupation values compared to the continental shelf area. Certain characteristics of the spatial distribution of sardine (e.g. spreading area, overlapping with anchovy differed substantially between the two ecosystems. Principal component analysis of geostatistical and spatial indicators revealed that biomass was significantly related to a suite of, rather than single, spatial indicators. At the spatial scale of our study, strong correlations emerged between biomass and the first principal component axis with highly positive loadings for occupation, aggregation and patchiness, independently of species and ecosystem. Overlapping between anchovy and sardine increased with the increase of sardine biomass but decreased with the increase of anchovy. This contrasting pattern was attributed to the location of the respective major patches

  13. Spatially explicit burden estimates of malaria in Tanzania: bayesian geostatistical modeling of the malaria indicator survey data.

    Science.gov (United States)

    Gosoniu, Laura; Msengwa, Amina; Lengeler, Christian; Vounatsou, Penelope

    2012-01-01

    A national HIV/AIDS and malaria parasitological survey was carried out in Tanzania in 2007-2008. In this study the parasitological data were analyzed: i) to identify climatic/environmental, socio-economic and interventions factors associated with child malaria risk and ii) to produce a contemporary, high spatial resolution parasitaemia risk map of the country. Bayesian geostatistical models were fitted to assess the association between parasitaemia risk and its determinants. bayesian kriging was employed to predict malaria risk at unsampled locations across Tanzania and to obtain the uncertainty associated with the predictions. Markov chain Monte Carlo (MCMC) simulation methods were employed for model fit and prediction. Parasitaemia risk estimates were linked to population data and the number of infected children at province level was calculated. Model validation indicated a high predictive ability of the geostatistical model, with 60.00% of the test locations within the 95% credible interval. The results indicate that older children are significantly more likely to test positive for malaria compared with younger children and living in urban areas and better-off households reduces the risk of infection. However, none of the environmental and climatic proxies or the intervention measures were significantly associated with the risk of parasitaemia. Low levels of malaria prevalence were estimated for Zanzibar island. The population-adjusted prevalence ranges from 0.29% in Kaskazini province (Zanzibar island) to 18.65% in Mtwara region. The pattern of predicted malaria risk is similar with the previous maps based on historical data, although the estimates are lower. The predicted maps could be used by decision-makers to allocate resources and target interventions in the regions with highest burden of malaria in order to reduce the disease transmission in the country.

  14. Geostatistical validation and cross-validation of magnetometric measurements of soil pollution with Potentially Toxic Elements in problematic areas

    Science.gov (United States)

    Fabijańczyk, Piotr; Zawadzki, Jarosław

    2016-04-01

    Field magnetometry is fast method that was previously effectively used to assess the potential soil pollution. One of the most popular devices that are used to measure the soil magnetic susceptibility on the soil surface is a MS2D Bartington. Single reading using MS2D device of soil magnetic susceptibility is low time-consuming but often characterized by considerable errors related to the instrument or environmental and lithogenic factors. In this connection, measured values of soil magnetic susceptibility have to be usually validated using more precise, but also much more expensive, chemical measurements. The goal of this study was to analyze validation methods of magnetometric measurements using chemical analyses of a concentration of elements in soil. Additionally, validation of surface measurements of soil magnetic susceptibility was performed using selected parameters of a distribution of magnetic susceptibility in a soil profile. Validation was performed using selected geostatistical measures of cross-correlation. The geostatistical approach was compared with validation performed using the classic statistics. Measurements were performed at selected areas located in the Upper Silesian Industrial Area in Poland, and in the selected parts of Norway. In these areas soil magnetic susceptibility was measured on the soil surface using a MS2D Bartington device and in the soil profile using MS2C Bartington device. Additionally, soil samples were taken in order to perform chemical measurements. Acknowledgment The research leading to these results has received funding from the Polish-Norwegian Research Programme operated by the National Centre for Research and Development under the Norwegian Financial Mechanism 2009-2014 in the frame of Project IMPACT - Contract No Pol-Nor/199338/45/2013.

  15. Interannual Changes in Biomass Affect the Spatial Aggregations of Anchovy and Sardine as Evidenced by Geostatistical and Spatial Indicators.

    Science.gov (United States)

    Barra, Marco; Petitgas, Pierre; Bonanno, Angelo; Somarakis, Stylianos; Woillez, Mathieu; Machias, Athanasios; Mazzola, Salvatore; Basilone, Gualtiero; Giannoulaki, Marianna

    2015-01-01

    Geostatistical techniques were applied and a series of spatial indicators were calculated (occupation, aggregation, location, dispersion, spatial autocorrelation and overlap) to characterize the spatial distributions of European anchovy and sardine during summer. Two ecosystems were compared for this purpose, both located in the Mediterranean Sea: the Strait of Sicily (upwelling area) and the North Aegean Sea (continental shelf area, influenced by freshwater). Although the biomass of anchovy and sardine presented high interannual variability in both areas, the location of the centres of gravity and the main spatial patches of their populations were very similar between years. The size of the patches representing the dominant part of the abundance (80%) was mostly ecosystem- and species-specific. Occupation (area of presence) appears to be shaped by the extent of suitable habitats in each ecosystem whereas aggregation patterns (how the populations are distributed within the area of presence) were species-specific and related to levels of population biomass. In the upwelling area, both species showed consistently higher occupation values compared to the continental shelf area. Certain characteristics of the spatial distribution of sardine (e.g. spreading area, overlapping with anchovy) differed substantially between the two ecosystems. Principal component analysis of geostatistical and spatial indicators revealed that biomass was significantly related to a suite of, rather than single, spatial indicators. At the spatial scale of our study, strong correlations emerged between biomass and the first principal component axis with highly positive loadings for occupation, aggregation and patchiness, independently of species and ecosystem. Overlapping between anchovy and sardine increased with the increase of sardine biomass but decreased with the increase of anchovy. This contrasting pattern was attributed to the location of the respective major patches combined with the

  16. Geostatistical Analyses of Soil Organic Carbon Concentrations in Aligodarz Watershed, Lorestan Province

    Directory of Open Access Journals (Sweden)

    Masoud Davari

    2017-01-01

    Full Text Available Introduction: Soil organic carbon (SOC has great impacts on soil properties, soil productivity, food security, land degradation and global warming. Similar to other soil properties, SOC has a strong spatial heterogeneity as a result of dynamic interactions between parent material, climate and geological history, at both regional and continental scales. However, landscape attributes including slope, aspect, altitude, and land use types are dominant factors influencing on SOC in areas with the same parent materials and climate regime. Understanding and identifying the spatial and temporal distribution of SOC is essential to evaluate soil quality, agricultural management, watershed modeling and soil carbon sequestration budgets. Therefore, the objectives of this study was to estimate soil organic carbon content in the Aligodarz watershed, and to investigate the effects of altitude, slope, and land use type on SOC. Materials and Methods: The research was carried out in the Aligodraz watershed in Lorestan province of Iran. The study area is located between latitudes N 33° 10' 51.72"to N 33° 34' 28.22" and longitudes E 49° 27' 17.99"to E 49° 58' 40.84" 14 that covers an area of 1078.9 km2. It has an altitude between 1866.3 and 3200 m above sea-level. The primary land uses within the watershed include pasture, dryland and irrigated farming. In this study, soil samples were randomly collected from 206 sites at depth of 0– 15 cm during June and August 2003. The mean distance between samples was about 5 km. Soil samples were air-dried in the shade for about 7 days and then passed through a 0.25 mm prior to determination of SOC. Soil organic carbon content was determined in triplicate for each sample using the Walkey-Black method. Basic statistical analyses for frequency distribution, normality tests, Pearson's correlation and analysis of variance were conducted using SPSS (version 18.0. Calculation of experimental variograms and modeling of spatial

  17. A Geostatistical Toolset for Reconstructing Louisiana's Coastal Stratigraphy using Subsurface Boring and Cone Penetrometer Test Data

    Science.gov (United States)

    Li, A.; Tsai, F. T. C.; Jafari, N.; Chen, Q. J.; Bentley, S. J.

    2017-12-01

    A vast area of river deltaic wetlands stretches across southern Louisiana coast. The wetlands are suffering from a high rate of land loss, which increasingly threats coastal community and energy infrastructure. A regional stratigraphic framework of the delta plain is now imperative to answer scientific questions (such as how the delta plain grows and decays?) and to provide information to coastal protection and restoration projects (such as marsh creation and construction of levees and floodwalls). Through years, subsurface investigations in Louisiana have been conducted by state and federal agencies (Louisiana Department of Natural Resources, United States Geological Survey, United States Army Corps of Engineers, etc.), research institutes (Louisiana Geological Survey, LSU Coastal Studies Institute, etc.), engineering firms, and oil-gas companies. This has resulted in the availability of various types of data, including geological, geotechnical, and geophysical data. However, it is challenging to integrate different types of data and construct three-dimensional stratigraphy models in regional scale. In this study, a set of geostatistical methods were used to tackle this problem. An ordinary kriging method was used to regionalize continuous data, such as grain size, water content, liquid limit, plasticity index, and cone penetrometer tests (CPTs). Indicator kriging and multiple indicator kriging methods were used to regionalize categorized data, such as soil classification. A compositional kriging method was used to regionalize compositional data, such as soil composition (fractions of sand, silt and clay). Stratigraphy models were constructed for three cases in the coastal zone: (1) Inner Harbor Navigation Canal (IHNC) area: soil classification and soil behavior type (SBT) stratigraphies were constructed using ordinary kriging; (2) Middle Barataria Bay area: a soil classification stratigraphy was constructed using multiple indicator kriging; (3) Lower Barataria

  18. Increasing the predictive power of geostatistical reservoir models by integration of geological constraints from stratigraphic forward modeling

    NARCIS (Netherlands)

    Sacchi, Q.; Borello, E.S.; Weltje, G.J.; Dalman, R.

    2016-01-01

    Current static reservoir models are created by quantitative integration of interpreted well and seismic data through geostatistical tools. In these models, equiprobable realizations of structural settings and property distributions can be generated by stochastic simulation techniques. The

  19. Geostatistical investigation into the temporal evolution of spatial structure in a shallow water table

    Directory of Open Access Journals (Sweden)

    S. W. Lyon

    2006-01-01

    Full Text Available Shallow water tables near-streams often lead to saturated, overland flow generating areas in catchments in humid climates. While these saturated areas are assumed to be principal biogeochemical hot-spots and important for issues such as non-point pollution sources, the spatial and temporal behavior of shallow water tables, and associated saturated areas, is not completely understood. This study demonstrates how geostatistical methods can be used to characterize the spatial and temporal variation of the shallow water table for the near-stream region. Event-based and seasonal changes in the spatial structure of the shallow water table, which influences the spatial pattern of surface saturation and related runoff generation, can be identified and used in conjunction to characterize the hydrology of an area. This is accomplished through semivariogram analysis and indicator kriging to produce maps combining soft data (i.e., proxy information to the variable of interest representing general shallow water table patterns with hard data (i.e., actual measurements that represent variation in the spatial structure of the shallow water table per rainfall event. The area used was a hillslope in the Catskill Mountains region of New York State. The shallow water table was monitored for a 120 m×180 m near-stream region at 44 sampling locations on 15-min intervals. Outflow of the area was measured at the same time interval. These data were analyzed at a short time interval (15 min and at a long time interval (months to characterize the changes in the hydrologic behavior of the hillslope. Indicator semivariograms based on binary-transformed ground water table data (i.e., 1 if exceeding the time-variable median depth to water table and 0 if not were created for both short and long time intervals. For the short time interval, the indicator semivariograms showed a high degree of spatial structure in the shallow water table for the spring, with increased range

  20. Use of geostatistic techniques to describe a reservoir to be submitted into a secondary recovery process field case: {open_quotes}Eocene B-Inferior/VLG-3659, Ceuta, Venezuela{close_quotes}

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, T.; Poquioma, W. [Maraven, S.A., Caracas (Venezuela)

    1997-08-01

    This study presents the results of an integrated reservoir study of the Eocene B-Inferior/VLG-3659, Area 7, Ceuta filed. This field located in the Maracaibo Lake in the western side of Venezuela. The objective was to evaluating the feasibility to implement a secondary recovery project by means of water flooding. Core information was used for this study (194 ft), PVT analysis, RFI, build-up and statistic`s pressure analysis, modem logs and production history data. Using geostatistical techniques (Kriging) it was defined a low uncertainty geological model that was validated by means of a black oil simulator (Eclipse). The results showed a good comparison of historical pressure of the reservoir against those obtained from the model, without the need of {open_quotes}history matching{close_quotes}. It means without modifying neither the initial rock properties nor reservoir fluids. The results of this study recommended drilling in two new locations, also the reactivation of four producing wells and water flooding under peripherical array by means of four injection wells, with the recovery of an additional 30.2 MMSTB. The economical evaluation shows an internal return rate of 31.4%.

  1. SRS 2010 Vegetation Inventory GeoStatistical Mapping Results for Custom Reaction Intensity and Total Dead Fuels.

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, Lloyd A. [Leading Solutions, LLC.; Paresol, Bernard [U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station, Portland, OR.

    2014-09-01

    This report of the geostatistical analysis results of the fire fuels response variables, custom reaction intensity and total dead fuels is but a part of an SRS 2010 vegetation inventory project. For detailed description of project, theory and background including sample design, methods, and results please refer to USDA Forest Service Savannah River Site internal report “SRS 2010 Vegetation Inventory GeoStatistical Mapping Report”, (Edwards & Parresol 2013).

  2. Spatially explicit Schistosoma infection risk in eastern Africa using Bayesian geostatistical modelling

    DEFF Research Database (Denmark)

    Schur, Nadine; Hürlimann, Eveline; Stensgaard, Anna-Sofie

    2013-01-01

    surveys on different age-groups and to acquire separate estimates for individuals aged ≤20 years and entire communities. Prevalence estimates were combined with population statistics to obtain country-specific numbers of Schistosoma infections. We estimate that 122 million individuals in eastern Africa...... Africa. Bayesian geostatistical models based on climatic and other environmental data were used to account for potential spatial clustering in spatially structured exposures. Geostatistical variable selection was employed to reduce the set of covariates. Alignment factors were implemented to combine...... are currently infected with either S. mansoni, or S. haematobium, or both species concurrently. Country-specific population-adjusted prevalence estimates range between 12.9% (Uganda) and 34.5% (Mozambique) for S. mansoni and between 11.9% (Djibouti) and 40.9% (Mozambique) for S. haematobium. Our models revealed...

  3. A geostatistical estimation of zinc grade in bore-core samples

    International Nuclear Information System (INIS)

    Starzec, A.

    1987-01-01

    Possibilities and preliminary results of geostatistical interpretation of the XRF determination of zinc in bore-core samples are considered. For the spherical model of the variogram the estimation variance of grade in a disk-shape sample (estimated from the grade on the circumference sample) is calculated. Variograms of zinc grade in core samples are presented and examples of the grade estimation are discussed. 4 refs., 7 figs., 1 tab. (author)

  4. Geostatistical interpolation model selection based on ArcGIS and spatio-temporal variability analysis of groundwater level in piedmont plains, northwest China.

    Science.gov (United States)

    Xiao, Yong; Gu, Xiaomin; Yin, Shiyang; Shao, Jingli; Cui, Yali; Zhang, Qiulan; Niu, Yong

    2016-01-01

    Based on the geo-statistical theory and ArcGIS geo-statistical module, datas of 30 groundwater level observation wells were used to estimate the decline of groundwater level in Beijing piedmont. Seven different interpolation methods (inverse distance weighted interpolation, global polynomial interpolation, local polynomial interpolation, tension spline interpolation, ordinary Kriging interpolation, simple Kriging interpolation and universal Kriging interpolation) were used for interpolating groundwater level between 2001 and 2013. Cross-validation, absolute error and coefficient of determination (R(2)) was applied to evaluate the accuracy of different methods. The result shows that simple Kriging method gave the best fit. The analysis of spatial and temporal variability suggest that the nugget effects from 2001 to 2013 were increasing, which means the spatial correlation weakened gradually under the influence of human activities. The spatial variability in the middle areas of the alluvial-proluvial fan is relatively higher than area in top and bottom. Since the changes of the land use, groundwater level also has a temporal variation, the average decline rate of groundwater level between 2007 and 2013 increases compared with 2001-2006. Urban development and population growth cause over-exploitation of residential and industrial areas. The decline rate of the groundwater level in residential, industrial and river areas is relatively high, while the decreasing of farmland area and development of water-saving irrigation reduce the quantity of water using by agriculture and decline rate of groundwater level in agricultural area is not significant.

  5. A comparison of geostatistically-based inverse techniques for use in performance assessment analyses at the WIPP site results from the Test Case No. 1

    International Nuclear Information System (INIS)

    Zimmerman, D.A.; Gallegos, D.P.

    1992-01-01

    The groundwater flow pathway in the Culebra Dolomite aquifer at the Waste Isolation Pilot Plant (WIPP) has been identified a potentially important pathway for radionuclide migration to the accessible environment. Consequently, uncertainties in the models used to describe flow and transport in the Culebra need to be addressed. A ''Geostatistics Test Problem'' is being developed to evaluate a number of inverse techniques that may be used for Dow calculations in the WIPP performance assessment (PA). The Test Problem is actually a series of test cases, each being developed as a highly complex synthetic data sct; the intent is for the ensemble of these data sets span the range of possible conceptual models of groundwater now at the WIPP site. This paper describes the results from Test Case No. 1. Of the five techniques compared, those based on the linearized form of the groundwater flow equation exhibited less bias and less spread in their GWTT distribution functions; the semi-analytical method had the least bias. While the results are not sufficient to make generalizations about which techniques may be better suited for the WIPP PA (only one test case has been exercised), analyses of the data from this test case provides some indication about the relative importance of other aspects of the flow modeling (besides inverse method or geostatistical approach) in PA. Then ancillary analyses examine the effect of gridding an the effect of boundary conditions on the groundwater travel time estimates

  6. Spatial Downscaling of TRMM Precipitation Using Geostatistics and Fine Scale Environmental Variables

    Directory of Open Access Journals (Sweden)

    No-Wook Park

    2013-01-01

    Full Text Available A geostatistical downscaling scheme is presented and can generate fine scale precipitation information from coarse scale Tropical Rainfall Measuring Mission (TRMM data by incorporating auxiliary fine scale environmental variables. Within the geostatistical framework, the TRMM precipitation data are first decomposed into trend and residual components. Quantitative relationships between coarse scale TRMM data and environmental variables are then estimated via regression analysis and used to derive trend components at a fine scale. Next, the residual components, which are the differences between the trend components and the original TRMM data, are then downscaled at a target fine scale via area-to-point kriging. The trend and residual components are finally added to generate fine scale precipitation estimates. Stochastic simulation is also applied to the residual components in order to generate multiple alternative realizations and to compute uncertainty measures. From an experiment using a digital elevation model (DEM and normalized difference vegetation index (NDVI, the geostatistical downscaling scheme generated the downscaling results that reflected detailed characteristics with better predictive performance, when compared with downscaling without the environmental variables. Multiple realizations and uncertainty measures from simulation also provided useful information for interpretations and further environmental modeling.

  7. Geostatistical and multivariate statistical analysis of heavily and manifoldly contaminated soil samples.

    Science.gov (United States)

    Schaefer, Kristin; Einax, Jürgen W; Simeonov, Vasil; Tsakovski, Stefan

    2010-04-01

    The surroundings of the former Kremikovtzi steel mill near Sofia (Bulgaria) are influenced by various emissions from the factory. In addition to steel and alloys, they produce different products based on inorganic compounds in different smelters. Soil in this region is multiply contaminated. We collected 65 soil samples and analyzed 15 elements by different methods of atomic spectroscopy for a survey of this field site. Here we present a novel hybrid approach for environmental risk assessment of polluted soil combining geostatistical methods and source apportionment modeling. We could distinguish areas with heavily and slightly polluted soils in the vicinity of the iron smelter by applying unsupervised pattern recognition methods. This result was supported by geostatistical methods such as semivariogram analysis and kriging. The modes of action of the metals examined differ significantly in such a way that iron and lead account for the main pollutants of the iron smelter, whereas, e.g., arsenic shows a haphazard distribution. The application of factor analysis and source-apportionment modeling on absolute principal component scores revealed novel information about the composition of the emissions from the different stacks. It is possible to estimate the impact of every element examined on the pollution due to their emission source. This investigation allows an objective assessment of the different spatial distributions of the elements examined in the soil of the Kremikovtzi region. The geostatistical analysis illustrates this distribution and is supported by multivariate statistical analysis revealing relations between the elements.

  8. Geostatistical integration and uncertainty in pollutant concentration surface under preferential sampling

    Directory of Open Access Journals (Sweden)

    Laura Grisotto

    2016-04-01

    Full Text Available In this paper the focus is on environmental statistics, with the aim of estimating the concentration surface and related uncertainty of an air pollutant. We used air quality data recorded by a network of monitoring stations within a Bayesian framework to overcome difficulties in accounting for prediction uncertainty and to integrate information provided by deterministic models based on emissions meteorology and chemico-physical characteristics of the atmosphere. Several authors have proposed such integration, but all the proposed approaches rely on representativeness and completeness of existing air pollution monitoring networks. We considered the situation in which the spatial process of interest and the sampling locations are not independent. This is known in the literature as the preferential sampling problem, which if ignored in the analysis, can bias geostatistical inferences. We developed a Bayesian geostatistical model to account for preferential sampling with the main interest in statistical integration and uncertainty. We used PM10 data arising from the air quality network of the Environmental Protection Agency of Lombardy Region (Italy and numerical outputs from the deterministic model. We specified an inhomogeneous Poisson process for the sampling locations intensities and a shared spatial random component model for the dependence between the spatial location of monitors and the pollution surface. We found greater predicted standard deviation differences in areas not properly covered by the air quality network. In conclusion, in this context inferences on prediction uncertainty may be misleading when geostatistical modelling does not take into account preferential sampling.

  9. Geostatistical modelling of soil-transmitted helminth infection in Cambodia: do socioeconomic factors improve predictions?

    Science.gov (United States)

    Karagiannis-Voules, Dimitrios-Alexios; Odermatt, Peter; Biedermann, Patricia; Khieu, Virak; Schär, Fabian; Muth, Sinuon; Utzinger, Jürg; Vounatsou, Penelope

    2015-01-01

    Soil-transmitted helminth infections are intimately connected with poverty. Yet, there is a paucity of using socioeconomic proxies in spatially explicit risk profiling. We compiled household-level socioeconomic data pertaining to sanitation, drinking-water, education and nutrition from readily available Demographic and Health Surveys, Multiple Indicator Cluster Surveys and World Health Surveys for Cambodia and aggregated the data at village level. We conducted a systematic review to identify parasitological surveys and made every effort possible to extract, georeference and upload the data in the open source Global Neglected Tropical Diseases database. Bayesian geostatistical models were employed to spatially align the village-aggregated socioeconomic predictors with the soil-transmitted helminth infection data. The risk of soil-transmitted helminth infection was predicted at a grid of 1×1km covering Cambodia. Additionally, two separate individual-level spatial analyses were carried out, for Takeo and Preah Vihear provinces, to assess and quantify the association between soil-transmitted helminth infection and socioeconomic indicators at an individual level. Overall, we obtained socioeconomic proxies from 1624 locations across the country. Surveys focussing on soil-transmitted helminth infections were extracted from 16 sources reporting data from 238 unique locations. We found that the risk of soil-transmitted helminth infection from 2000 onwards was considerably lower than in surveys conducted earlier. Population-adjusted prevalences for school-aged children from 2000 onwards were 28.7% for hookworm, 1.5% for Ascaris lumbricoides and 0.9% for Trichuris trichiura. Surprisingly, at the country-wide analyses, we did not find any significant association between soil-transmitted helminth infection and village-aggregated socioeconomic proxies. Based also on the individual-level analyses we conclude that socioeconomic proxies might not be good predictors at an

  10. Geostatistical estimates of future recharge for the Death Valley region

    International Nuclear Information System (INIS)

    Hevesi, J.A.; Flint, A.L.

    1998-01-01

    Spatially distributed estimates of regional ground water recharge rates under both current and potential future climates are needed to evaluate a potential geologic repository for high-level nuclear waste at Yucca Mountain, Nevada, which is located within the Death Valley ground-water region (DVGWR). Determining the spatial distribution of recharge is important for regional saturated-zone ground-water flow models. In the southern Nevada region, the Maxey-Eakin method has been used for estimating recharge based on average annual precipitation. Although this method does not directly account for a variety of location-specific factors which control recharge (such as bedrock permeability, soil cover, and net radiation), precipitation is the primary factor that controls in the region. Estimates of recharge obtained by using the Maxey-Eakin method are comparable to estimates of recharge obtained by using chloride balance studies. The authors consider the Maxey-Eakin approach as a relatively simple method of obtaining preliminary estimates of recharge on a regional scale

  11. Geostatistical characterization of the Callovo-Oxfordian clay variability: from conventional and high resolution log data

    International Nuclear Information System (INIS)

    Lefranc, Marie

    2007-01-01

    Andra (National Radioactive Waste Management Agency) has conducted studies in its Meuse/Haute-Marne Underground Research Laboratory located at a depth of about 490 m in a 155-million-year-old argillaceous rock: the Callovo-Oxfordian argillite. The purpose of the present work is to obtain as much information as possible from high-resolution log data and to optimize their analysis to specify and characterize space-time variations of the argillites from the Meuse/Haute-Marne site and subsequently predict the evolution of argillite properties on a 250 km 2 zone around the underground laboratory (transposition zone). The aim is to outline a methodology to transform depth intervals into geological time intervals and thus to quantify precisely the sedimentation rate variation, estimate duration; for example the duration of bio-stratigraphical units or of hiatuses. The latter point is particularly important because a continuous time recording is often assumed in geological modelling. The spatial variations can be studied on various scales. First, well-to-well correlations are established between seven wells at different scales. Relative variations of the thickness are observed locally. Second, FMI (Full-bore Formation Micro-Imager, Schlumberger) data are studied in detail to extract as much information as possible. For example, the analysis of FMI images reveals a clear carbonate - clay inter-bedding which displays cycles. Third, geostatistical tools are used to study these cycles. The vario-graphic analysis of conventional log data shows one metre cycles. With FMI data, smaller periods can be detected. Variogram modelling and factorial kriging analysis suggest that three spatial periods exist. They vary vertically and laterally in the boreholes but cycle ratios are stable and similar to orbital-cycle ratios (Milankovitch cycles). The three periods correspond to eccentricity, obliquity and precession. Since the duration of these orbital cycles is known, depth intervals can

  12. Potential of deterministic and geostatistical rainfall interpolation under high rainfall variability and dry spells: case of Kenya's Central Highlands

    Science.gov (United States)

    Kisaka, M. Oscar; Mucheru-Muna, M.; Ngetich, F. K.; Mugwe, J.; Mugendi, D.; Mairura, F.; Shisanya, C.; Makokha, G. L.

    2016-04-01

    Drier parts of Kenya's Central Highlands endure persistent crop failure and declining agricultural productivity. These have, in part, attributed to high temperatures, prolonged dry spells and erratic rainfall. Understanding spatial-temporal variability of climatic indices such as rainfall at seasonal level is critical for optimal rain-fed agricultural productivity and natural resource management in the study area. However, the predominant setbacks in analysing hydro-meteorological events are occasioned by either lack, inadequate, or inconsistent meteorological data. Like in most other places, the sole sources of climatic data in the study region are scarce and only limited to single stations, yet with persistent missing/unrecorded data making their utilization a challenge. This study examined seasonal anomalies and variability in rainfall, drought occurrence and the efficacy of interpolation techniques in the drier regions of eastern Kenyan. Rainfall data from five stations (Machang'a, Kiritiri, Kiambere and Kindaruma and Embu) were sourced from both the Kenya Meteorology Department and on-site primary recording. Owing to some experimental work ongoing, automated recording for primary dailies in Machang'a have been ongoing since the year 2000 to date; thus, Machang'a was treated as reference (for period of record) station for selection of other stations in the region. The other stations had data sets of over 15 years with missing data of less than 10 % as required by the world meteorological organization whose quality check is subject to the Centre for Climate Systems Modeling (C2SM) through MeteoSwiss and EMPA bodies. The dailies were also subjected to homogeneity testing to evaluate whether they came from the same population. Rainfall anomaly index, coefficients of variance and probability were utilized in the analyses of rainfall variability. Spline, kriging and inverse distance weighting interpolation techniques were assessed using daily rainfall data and

  13. Diagnostic techniques applied in geostatistics for agricultural data analysis Técnicas de diagnóstico utilizadas em geoestatística para análise de dados agrícolas

    Directory of Open Access Journals (Sweden)

    Joelmir André Borssoi

    2009-12-01

    Full Text Available The structural modeling of spatial dependence, using a geostatistical approach, is an indispensable tool to determine parameters that define this structure, applied on interpolation of values at unsampled points by kriging techniques. However, the estimation of parameters can be greatly affected by the presence of atypical observations in sampled data. The purpose of this study was to use diagnostic techniques in Gaussian spatial linear models in geostatistics to evaluate the sensitivity of maximum likelihood and restrict maximum likelihood estimators to small perturbations in these data. For this purpose, studies with simulated and experimental data were conducted. Results with simulated data showed that the diagnostic techniques were efficient to identify the perturbation in data. The results with real data indicated that atypical values among the sampled data may have a strong influence on thematic maps, thus changing the spatial dependence structure. The application of diagnostic techniques should be part of any geostatistical analysis, to ensure a better quality of the information from thematic maps.A modelagem da estrutura de dependência espacial pela abordagem da geoestatística é de fundamental importância para a definição de parâmetros que definem essa estrutura e que são utilizados na interpolação de valores em locais não amostrados, pela técnica de krigagem. Entretanto, a estimação de parâmetros pode ser muito alterada pela presença de observações atípicas nos dados amostrados. O desenvolvimento deste trabalho teve por objetivo utilizar técnicas de diagnóstico em modelos espaciais lineares gaussianos, empregados em geoestatística, para avaliar a sensibilidade dos estimadores de máxima verossimilhança e máxima verossimilhança restrita a pequenas perturbações nos dados. Foram realizados estudos de dados simulados e experimentais. O estudo com dados simulados mostrou que as técnicas de diagnóstico foram

  14. Stochastic simulation of time-series models combined with geostatistics to predict water-table scenarios in a Guarani Aquifer System outcrop area, Brazil

    Science.gov (United States)

    Manzione, Rodrigo L.; Wendland, Edson; Tanikawa, Diego H.

    2012-11-01

    Stochastic methods based on time-series modeling combined with geostatistics can be useful tools to describe the variability of water-table levels in time and space and to account for uncertainty. Monitoring water-level networks can give information about the dynamic of the aquifer domain in both dimensions. Time-series modeling is an elegant way to treat monitoring data without the complexity of physical mechanistic models. Time-series model predictions can be interpolated spatially, with the spatial differences in water-table dynamics determined by the spatial variation in the system properties and the temporal variation driven by the dynamics of the inputs into the system. An integration of stochastic methods is presented, based on time-series modeling and geostatistics as a framework to predict water levels for decision making in groundwater management and land-use planning. The methodology is applied in a case study in a Guarani Aquifer System (GAS) outcrop area located in the southeastern part of Brazil. Communication of results in a clear and understandable form, via simulated scenarios, is discussed as an alternative, when translating scientific knowledge into applications of stochastic hydrogeology in large aquifers with limited monitoring network coverage like the GAS.

  15. Geochemical mapping in polluted floodplains using handheld XRF, geophysical imaging, and geostatistics

    Science.gov (United States)

    Hošek, Michal; Matys Grygar, Tomáš; Popelka, Jan; Kiss, Timea; Elznicová, Jitka; Faměra, Martin

    2017-04-01

    In the recent years researchers have enjoyed noticeable improvements of portable analytical and geophysical methods, which allow studying floodplain architecture and deciphering pollutant distribution more easily than ever before. Our area of interest was floodplain of the Ploučnice River, particularly a pollution hotspot in Boreček, severely impacted by U mining between the 1970s and late 1980s, in particular a "radioactive flood" in 1981. In the area, we used hand drill coring and in situ (field) analysis of so acquired sediments by handheld X-ray fluorescence spectrometer (XRF), which gave us information about depth profiles of pollutants (Ba, U, Zn) and the Al/Si and Zr/Rb ratios, i.e., proxies for sediment lithology. We found that spatial distribution of pollutants (control by depth and position in the floodplain) is apparently complex and discontinuous. In some places, contamination is buried by a couple decimetres of less polluted sediments, while in other places the peak pollution is near surface, apparently without a straightforward connection with the surface topography and the distance to the river channel. We thus examined the floodplain architecture, the internal structure of the floodplain using two geophysical methods. First of them, dipole electromagnetic profiling (DEMP, also denoted EMP, MP, or Slingram) quickly acquires average electric resistivity in top strata in selected areas, which was actually top 3 m with our particular instrument. Second, electric resistivity tomography (ERT) produces much more detailed information on resistivity with depth resolution of ca 0.5 m to the depth of ca 5 m in selected lines. ERT thus allows identifying boundaries of electric resistivity domains (sediment bodies) and DEMP their spatial distribution. Based on the obtained data, we divided the floodplain to five segments with specific topography, pollution characteristics, and electric resistivity. We suppose that those segments are lithogenetic floodplain

  16. Geostatistical interpolation for modelling SPT data in northern Izmir

    Indian Academy of Sciences (India)

    for depth, hammer energy, rod length, sampler, borehole diameter and fines content, to the data in hand. .... energy (CE), rod length (CR), sampler (CS), borehole diameter (CB) and fines content (Cfines) correction factors ..... In addi- tion to MAE, Root Mean Square Error (RMSE) is a common parameter used in evaluation of.

  17. Spatial Distribution and Mobility Assessment of Carcinogenic Heavy Metals in Soil Profiles Using Geostatistics and Random Forest, Boruta Algorithm

    Directory of Open Access Journals (Sweden)

    Asma Shaheen

    2018-03-01

    Full Text Available In third world countries, industries mainly cause environmental contamination due to lack of environmental policies or oversight during their implementation. The Sheikhupura industrial zone, which includes industries such as tanneries, leather, chemical, textiles, and colour and dyes, contributes massive amounts of untreated effluents that are released directly into drains and used for the irrigation of crops and vegetables. This practice causes not only soil contamination with an excessive amount of heavy metals, but is also considered a source of toxicity in the food chain, i.e., bioaccumulation in plants and ultimately in human body organs. The objective of this research study was to assess the spatial distribution of the heavy metals chromium (Cr, cadmium (Cd, and lead (Pb, at three depths of soil using geostatistics and the selection of significant contributing variables to soil contamination using the Random Forest (RF function of the Boruta Algorithm. A total of 60 sampling locations were selected in the study area to collect soil samples (180 samples at three depths (0–15 cm, 15–30 cm, and 60–90 cm. The soil samples were analysed for their physico-chemical properties, i.e., soil saturation, electrical conductivity (EC, organic matter (OM, pH, phosphorus (P, potassium (K, and Cr, Cd, and Pb using standard laboratory procedures. The data were analysed with comprehensive statistics and geostatistical techniques. The correlation coefficient matrix between the heavy metals and the physico-chemical properties revealed that electrical conductivity (EC had a significant (p ≤ 0.05 negative correlation with Cr, Cd, and Pb. The RF function of the Boruta Algorithm employed soil depth as a classifier and ranked the significant soil contamination parameters (Cr, Cd, Pb, EC, and P in relation to depth. The mobility factor indicated the leachate percentage of heavy metals at different vertical depths of soil. The spatial distribution pattern of

  18. Conditioning geostatistical simulations of a heterogeneous paleo-fluvial bedrock aquifer using lithologs and pumping tests

    Science.gov (United States)

    Niazi, A.; Bentley, L. R.; Hayashi, M.

    2016-12-01

    Geostatistical simulations are used to construct heterogeneous aquifer models. Optimally, such simulations should be conditioned with both lithologic and hydraulic data. We introduce an approach to condition lithologic geostatistical simulations of a paleo-fluvial bedrock aquifer consisting of relatively high permeable sandstone channels embedded in relatively low permeable mudstone using hydraulic data. The hydraulic data consist of two-hour single well pumping tests extracted from the public water well database for a 250-km2 watershed in Alberta, Canada. First, lithologic models of the entire watershed are simulated and conditioned with hard lithological data using transition probability - Markov chain geostatistics (TPROGS). Then, a segment of the simulation around a pumping well is used to populate a flow model (FEFLOW) with either sand or mudstone. The values of the hydraulic conductivity and specific storage of sand and mudstone are then adjusted to minimize the difference between simulated and actual pumping test data using the parameter estimation program PEST. If the simulated pumping test data do not adequately match the measured data, the lithologic model is updated by locally deforming the lithology distribution using the probability perturbation method and the model parameters are again updated with PEST. This procedure is repeated until the simulated and measured data agree within a pre-determined tolerance. The procedure is repeated for each well that has pumping test data. The method creates a local groundwater model that honors both the lithologic model and pumping test data and provides estimates of hydraulic conductivity and specific storage. Eventually, the simulations will be integrated into a watershed-scale groundwater model.

  19. Geostatistical interpolation of field data in three dimensions to assess nitrate leaching to groundwater

    Science.gov (United States)

    Onsoy, S. Y.; Harter, T.; Ginn, T.; Hopmans, J. W.; Horwath, W.

    2003-04-01

    Groundwater deterioration and associated environmental problems induced by nitrate applications in agricultural areas are a growing concern worldwide. Estimation of downward nitrate flux to groundwater is a major concern due to its extensive use, high mobility and persistence in the environment. The overall goal of our research is to better understand the role of deep alluvial unsaturated zone in controlling the long term impact of California Central Valley agricultural practices on groundwater quality. We describe the quantitative analysis of the subsurface N budget in a 16 m thick vadose zone utilizing the data obtained from the 12-year N fertilizer experiment (1982-1995) conducted on an alluvial fan of the Kings River in the Central Valley of California. Three alternative N management practices with an annual fertilizer rate of 0, 100 and 325 lbs N/ac are compared, by high-resolution sampling of the vadose zone 12 years after initiation of the applications. Here we report on spatial statistics of the collected data on water content, nitrate, etc. The results from directional experimental semivariograms are rather striking. Nitrate data, while widely variable, have a significant spatial continuity in the vertical direction while the sill is identical both in the horizontal and vertical directions. In the case of soil moisture data, however, the sill in the horizontal direction is smaller while the range is significantly longer than in the vertical direction, indicating that moisture flux is predominantly vertical despite the strong stratigraphic heterogeneity. The results from the variogram analysis are incorporated in the kriging interpolation to analyze the effects of spatial structure of the data in the estimation of N mass. We employ two methods to estimate the risk of nitrate loss from the root zone: mass balance of the N fluxes in the root zone and deep vadose zone N mass assessment via geostatistical analysis. From both methods we obtain excess N available

  20. Groundwater levels time series sensitivity to pluviometry and air temperature: a geostatistical approach to Sfax region, Tunisia.

    Science.gov (United States)

    Triki, Ibtissem; Trabelsi, Nadia; Hentati, Imen; Zairi, Moncef

    2014-03-01

    In this paper, the pattern of groundwater level fluctuations is investigated by statistical techniques for 24 monitoring wells located in an unconfined coastal aquifer in Sfax (Tunisia) for a time period from 1997 to 2006. Firstly, a geostatistical study is performed to characterize the temporal behaviors of data sets in terms of variograms and to make predictions about the value of the groundwater level at unsampled times. Secondly, multivariate statistical methods, i.e., principal component analysis (PCA) and cluster analysis (CA) of time series of groundwater levels are used to classify groundwater hydrographs regard to identical fluctuation pattern. Three groundwater groups (A, B, and C) were identified. In group "A," water level decreases continuously throughout the study periods with rapid annual cyclic variation, whereas in group "B," the water level contains much less high-frequency variation. The wells of group "C" represents a steady and gradual increase of groundwater levels caused by the aquifer artificial recharge. Furthermore, a cross-correlation analysis is used to investigate the aquifer response to local rainfall and temperature records. The result revealed that the temperature is more affecting the variation of the groundwater level of group A wells than the rainfall. However, the second and the third groups are less affected by rainfall or temperature.

  1. Impact of additional small-scale survey data on the geostatistical analyses of demersal fish species in the North Sea

    Directory of Open Access Journals (Sweden)

    Vanessa Stelzenmüller

    2005-12-01

    Full Text Available Geostatistical tools have been used to study the impact of additional small scale catch data (star survey design on the spatial analysis of fish, regarding different biological groups of dab, Limanda limanda and whiting, Merlangius merlangus. A standard survey carried out in January (2001-2003 in a meso-scale area in the German Bight was modified by additional small-scale sampling in 2002 and 2003. Adopting the star survey reduced the small-scale variability for medium-sized and male dab, as indicated by lower values of the nugget effect and an increased resolution of the spatial dependency. For whiting no reduction in the small scale variability could be detected; a significant difference in the spatial structuring was only found for two different size groups of whiting. Uncertainty of mean catches of dab and whiting was reduced in 2002, while in 2003 the effect of the star survey was less pronounced due to the high local density of the nearby stations. We conclude that the star survey design can be an inexpensive and effective procedure — depending on the species studied and/or the positioning of the nearby stations — when a minimised small-scale variability and a reduction of uncertainty in mean biomass of fish are the focus of interest.

  2. Detection of terrain indices related to soil salinity and mapping salt-affected soils using remote sensing and geostatistical techniques.

    Science.gov (United States)

    Triki Fourati, Hela; Bouaziz, Moncef; Benzina, Mourad; Bouaziz, Samir

    2017-04-01

    Traditional surveying methods of soil properties over landscapes are dramatically cost and time-consuming. Thus, remote sensing is a proper choice for monitoring environmental problem. This research aims to study the effect of environmental factors on soil salinity and to map the spatial distribution of this salinity over the southern east part of Tunisia by means of remote sensing and geostatistical techniques. For this purpose, we used Advanced Spaceborne Thermal Emission and Reflection Radiometer data to depict geomorphological parameters: elevation, slope, plan curvature (PLC), profile curvature (PRC), and aspect. Pearson correlation between these parameters and soil electrical conductivity (EC soil ) showed that mainly slope and elevation affect the concentration of salt in soil. Moreover, spectral analysis illustrated the high potential of short-wave infrared (SWIR) bands to identify saline soils. To map soil salinity in southern Tunisia, ordinary kriging (OK), minimum distance (MD) classification, and simple regression (SR) were used. The findings showed that ordinary kriging technique provides the most reliable performances to identify and classify saline soils over the study area with a root mean square error of 1.83 and mean error of 0.018.

  3. NORTHERN OHIO AEROSOL STUDY: STAPHYLOCOCCUS AUREUS EVALUATION

    Science.gov (United States)

    A consortium of Universities, located in northwest Ohio have received funds to conduct a comprehensive evaluation of land applied biosolids in that state. This USDA funded study includes observing land application practices and evaluating biosolids, soils, runoff water and bioaer...

  4. Crescent Evaluation : appendix B : state case study evaluation report

    Science.gov (United States)

    1994-02-01

    The state case study evaluation approach uniquely captured an understanding of the potential of such a system by documenting the experiences, issues, and opportunities of selected key state government personnel from a cross-section of involved agenci...

  5. Merging parallel tempering with sequential geostatistical resampling for improved posterior exploration of high-dimensional subsurface categorical fields

    Science.gov (United States)

    Laloy, Eric; Linde, Niklas; Jacques, Diederik; Mariethoz, Grégoire

    2016-04-01

    The sequential geostatistical resampling (SGR) algorithm is a Markov chain Monte Carlo (MCMC) scheme for sampling from possibly non-Gaussian, complex spatially-distributed prior models such as geologic facies or categorical fields. In this work, we highlight the limits of standard SGR for posterior inference of high-dimensional categorical fields with realistically complex likelihood landscapes and benchmark a parallel tempering implementation (PT-SGR). Our proposed PT-SGR approach is demonstrated using synthetic (error corrupted) data from steady-state flow and transport experiments in categorical 7575- and 10,000-dimensional 2D conductivity fields. In both case studies, every SGR trial gets trapped in a local optima while PT-SGR maintains an higher diversity in the sampled model states. The advantage of PT-SGR is most apparent in an inverse transport problem where the posterior distribution is made bimodal by construction. PT-SGR then converges towards the appropriate data misfit much faster than SGR and partly recovers the two modes. In contrast, for the same computational resources SGR does not fit the data to the appropriate error level and hardly produces a locally optimal solution that looks visually similar to one of the two reference modes. Although PT-SGR clearly surpasses SGR in performance, our results also indicate that using a small number (16-24) of temperatures (and thus parallel cores) may not permit complete sampling of the posterior distribution by PT-SGR within a reasonable computational time (less than 1-2 weeks).

  6. Spatial variability of soil pH based on GIS combined with geostatistics in Panzhihua tobacco area

    International Nuclear Information System (INIS)

    Du Wei; Wang Changquan; Li Bing; Li Qiquan; Du Qian; Hu Jianxin; Liu Chaoke

    2012-01-01

    GIS and geostatistics were utilized to study the spatial variability of soil pH in Panzhihua tobacco area. Results showed that pH values in this area ranged from 4.5 to 8.3, especially 5.5 to 6.5, and in few areas were lower than 5.0 or higher than 7.0 which can meet the need of high-quality tobacco production. The best fitting model of variogram was exponential model with the nugget/sill of soil pH in 13.61% indicating strong spatial correlation. The change process was 5.40 km and the coefficient of determination was 0.491. The spatial variability of soil pH was mainly caused by structural factors such as cane, topography and soil type. The soil pH in Panzhihua tobacco area also showed a increasing trend of northwest to southeast trend. The pH of some areas in Caochang, Gonghe and Yumen were lower, and in Dalongtan were slightly higher. (authors)

  7. Thin sand modeling based on geostatistic, uncertainty and risk analysis in Zuata Principal field, Orinoco oil belt

    Energy Technology Data Exchange (ETDEWEB)

    Cardona, W.; Aranaga, R.; Siu, P.; Perez, L. [PDVSA Petroleos de Venezuela SA, Caracas (Venezuela, Bolivarian Republic of)

    2009-07-01

    The geological modelling of the Zuata Principal field in Venezuela, particularly the Junin Block 2 belonging to Orinoco oil belt, is a challenge because of the presence of thin sand bodies in an unexploited zone. This paper presented the results obtained from a horizontal well that contacted 96 per cent of pay count sand in the field. Geostatistical modelling and sensibility analysis were used for planning the well. The model was generated by processing and interpreting information from production and exploratory fishbones. Information provided by nearby wildcat wells suggested that the proposed area was not prospective. However, information provided by several exploratory fishbones offered some possibility of draining additional reserves. From available information, facies models and uncertainty analysis were made to statistically determine the best option, notably to drill additional stratwells to obtain a more accurate characterization or apply the already obtained model for drilling a production well in the investigated area. The study showed that geological uncertainty does not only depend on how much information is available, but also on how this information can be processed and interpreted. Decision analysis provides a rational basis for dealing with risk and uncertainties. 4 refs., 7 tabs., 7 figs., 1 appendix.

  8. Quantifying aggregated uncertainty in Plasmodium falciparum malaria prevalence and populations at risk via efficient space-time geostatistical joint simulation.

    Science.gov (United States)

    Gething, Peter W; Patil, Anand P; Hay, Simon I

    2010-04-01

    Risk maps estimating the spatial distribution of infectious diseases are required to guide public health policy from local to global scales. The advent of model-based geostatistics (MBG) has allowed these maps to be generated in a formal statistical framework, providing robust metrics of map uncertainty that enhances their utility for decision-makers. In many settings, decision-makers require spatially aggregated measures over large regions such as the mean prevalence within a country or administrative region, or national populations living under different levels of risk. Existing MBG mapping approaches provide suitable metrics of local uncertainty--the fidelity of predictions at each mapped pixel--but have not been adapted for measuring uncertainty over large areas, due largely to a series of fundamental computational constraints. Here the authors present a new efficient approximating algorithm that can generate for the first time the necessary joint simulation of prevalence values across the very large prediction spaces needed for global scale mapping. This new approach is implemented in conjunction with an established model for P. falciparum allowing robust estimates of mean prevalence at any specified level of spatial aggregation. The model is used to provide estimates of national populations at risk under three policy-relevant prevalence thresholds, along with accompanying model-based measures of uncertainty. By overcoming previously unchallenged computational barriers, this study illustrates how MBG approaches, already at the forefront of infectious disease mapping, can be extended to provide large-scale aggregate measures appropriate for decision-makers.

  9. Quantifying aggregated uncertainty in Plasmodium falciparum malaria prevalence and populations at risk via efficient space-time geostatistical joint simulation.

    Directory of Open Access Journals (Sweden)

    Peter W Gething

    2010-04-01

    Full Text Available Risk maps estimating the spatial distribution of infectious diseases are required to guide public health policy from local to global scales. The advent of model-based geostatistics (MBG has allowed these maps to be generated in a formal statistical framework, providing robust metrics of map uncertainty that enhances their utility for decision-makers. In many settings, decision-makers require spatially aggregated measures over large regions such as the mean prevalence within a country or administrative region, or national populations living under different levels of risk. Existing MBG mapping approaches provide suitable metrics of local uncertainty--the fidelity of predictions at each mapped pixel--but have not been adapted for measuring uncertainty over large areas, due largely to a series of fundamental computational constraints. Here the authors present a new efficient approximating algorithm that can generate for the first time the necessary joint simulation of prevalence values across the very large prediction spaces needed for global scale mapping. This new approach is implemented in conjunction with an established model for P. falciparum allowing robust estimates of mean prevalence at any specified level of spatial aggregation. The model is used to provide estimates of national populations at risk under three policy-relevant prevalence thresholds, along with accompanying model-based measures of uncertainty. By overcoming previously unchallenged computational barriers, this study illustrates how MBG approaches, already at the forefront of infectious disease mapping, can be extended to provide large-scale aggregate measures appropriate for decision-makers.

  10. The effect of training image and secondary data integration with multiple-point geostatistics in groundwater modelling

    DEFF Research Database (Denmark)

    He, Xin; Sonnenborg, Torben; Jørgensen, F.

    2014-01-01

    Multiple-point geostatistical simulation (MPS) has recently become popular in stochastic hydrogeology, primarily because of its capability to derive multivariate distributions from a training image (TI). However, its application in three-dimensional (3-D) simulations has been constrained by the d...... is a convenient and efficient way of integrating secondary data such as 3-D airborne electromagnetic data (SkyTEM), but over-conditioning has to be avoided....... by the difficulty of constructing a 3-D TI. The object-based unconditional simulation program TiGenerator may be a useful tool in this regard; yet the applicability of such parametric training images has not been documented in detail. Another issue in MPS is the integration of multiple geophysical data. The proper...... way to retrieve and incorporate information from high-resolution geophysical data is still under discussion. In this study, MPS simulation was applied to different scenarios regarding the TI and soft conditioning. By comparing their output from simulations of groundwater flow and probabilistic capture...

  11. Geostatistical interpolation for modelling SPT data in northern Izmir

    Indian Academy of Sciences (India)

    http://www.ias.ac.in/article/fulltext/sadh/038/06/1451-1468. Keywords. Kriging; SPT; site investigations; land-use planning; modelling; Northern Izmir. Abstract. In this study, it was aimed to map the corrected Standard Penetration Test(SPT) values in Karşıyaka city center by kriging approach. Six maps were prepared by this ...

  12. Geostatistical interpolation for modelling SPT data in northern Izmir

    Indian Academy of Sciences (India)

    to the data in hand. At various depths, prepared variograms and the kriging method were used together to model the variation of corrected SPT data in the region, which enabled ... backs and application of different tests on various types of soils requires an extensive study in decision ..... It should be added that, a big amount.

  13. Timescape: a simple space-time interpolation geostatistical Algorithm

    Science.gov (United States)

    Ciolfi, Marco; Chiocchini, Francesca; Gravichkova, Olga; Pisanelli, Andrea; Portarena, Silvia; Scartazza, Andrea; Brugnoli, Enrico; Lauteri, Marco

    2016-04-01

    explored in many ways, including the extraction of time series at fixed locations and GIS layers at constant times, allowing for the inclusion of the model in the users' established workflow. The software requirements are relatively modest since it has been purposely designed for potential users in various research field with a limited computing power at their disposal. Any respectful modern PC or laptop can run it. Users however need a separate database for sample data and models storage because these can be quite bulky in terms of data output: a single model can be composed of several billions of voxels (three-dimensional discrete cells, a sort of 3D pixels). Running times range from a few minutes for sketch models to some days of evaluation for a full-size model, depending on the users' hardware and model size.

  14. PCTO-SIM: Multiple-point geostatistical modeling using parallel conditional texture optimization

    Science.gov (United States)

    Pourfard, Mohammadreza; Abdollahifard, Mohammad J.; Faez, Karim; Motamedi, Sayed Ahmad; Hosseinian, Tahmineh

    2017-05-01

    Multiple-point Geostatistics is a well-known general statistical framework by which complex geological phenomena have been modeled efficiently. Pixel-based and patch-based are two major categories of these methods. In this paper, the optimization-based category is used which has a dual concept in texture synthesis as texture optimization. Our extended version of texture optimization uses the energy concept to model geological phenomena. While honoring the hard point, the minimization of our proposed cost function forces simulation grid pixels to be as similar as possible to training images. Our algorithm has a self-enrichment capability and creates a richer training database from a sparser one through mixing the information of all surrounding patches of the simulation nodes. Therefore, it preserves pattern continuity in both continuous and categorical variables very well. It also shows a fuzzy result in its every realization similar to the expected result of multi realizations of other statistical models. While the main core of most previous Multiple-point Geostatistics methods is sequential, the parallel main core of our algorithm enabled it to use GPU efficiently to reduce the CPU time. One new validation method for MPS has also been proposed in this paper.

  15. Bridges between multiple-point geostatistics and texture synthesis: Review and guidelines for future research

    Science.gov (United States)

    Mariethoz, Gregoire; Lefebvre, Sylvain

    2014-05-01

    Multiple-Point Simulations (MPS) is a family of geostatistical tools that has received a lot of attention in recent years for the characterization of spatial phenomena in geosciences. It relies on the definition of training images to represent a given type of spatial variability, or texture. We show that the algorithmic tools used are similar in many ways to techniques developed in computer graphics, where there is a need to generate large amounts of realistic textures for applications such as video games and animated movies. Similarly to MPS, these texture synthesis methods use training images, or exemplars, to generate realistic-looking graphical textures. Both domains of multiple-point geostatistics and example-based texture synthesis present similarities in their historic development and share similar concepts. These disciplines have however remained separated, and as a result significant algorithmic innovations in each discipline have not been universally adopted. Texture synthesis algorithms present drastically increased computational efficiency, patterns reproduction and user control. At the same time, MPS developed ways to condition models to spatial data and to produce 3D stochastic realizations, which have not been thoroughly investigated in the field of texture synthesis. In this paper we review the possible links between these disciplines and show the potential and limitations of using concepts and approaches from texture synthesis in MPS. We also provide guidelines on how recent developments could benefit both fields of research, and what challenges remain open.

  16. Efficient geostatistical inversion of transient groundwater flow using preconditioned nonlinear conjugate gradients

    Science.gov (United States)

    Klein, Ole; Cirpka, Olaf A.; Bastian, Peter; Ippisch, Olaf

    2017-04-01

    In the geostatistical inverse problem of subsurface hydrology, continuous hydraulic parameter fields, in most cases hydraulic conductivity, are estimated from measurements of dependent variables, such as hydraulic heads, under the assumption that the parameter fields are autocorrelated random space functions. Upon discretization, the continuous fields become large parameter vectors with O (104 -107) elements. While cokriging-like inversion methods have been shown to be efficient for highly resolved parameter fields when the number of measurements is small, they require the calculation of the sensitivity of each measurement with respect to all parameters, which may become prohibitive with large sets of measured data such as those arising from transient groundwater flow. We present a Preconditioned Conjugate Gradient method for the geostatistical inverse problem, in which a single adjoint equation needs to be solved to obtain the gradient of the objective function. Using the autocovariance matrix of the parameters as preconditioning matrix, expensive multiplications with its inverse can be avoided, and the number of iterations is significantly reduced. We use a randomized spectral decomposition of the posterior covariance matrix of the parameters to perform a linearized uncertainty quantification of the parameter estimate. The feasibility of the method is tested by virtual examples of head observations in steady-state and transient groundwater flow. These synthetic tests demonstrate that transient data can reduce both parameter uncertainty and time spent conducting experiments, while the presented methods are able to handle the resulting large number of measurements.

  17. Reservoir Modeling Combining Geostatistics with Markov Chain Monte Carlo Inversion

    DEFF Research Database (Denmark)

    Zunino, Andrea; Lange, Katrine; Melnikova, Yulia

    2014-01-01

    We present a study on the inversion of seismic reflection data generated from a synthetic reservoir model. Our aim is to invert directly for rock facies and porosity of the target reservoir zone. We solve this inverse problem using a Markov chain Monte Carlo (McMC) method to handle the nonlinear,...... constitute samples of the posterior distribution.......We present a study on the inversion of seismic reflection data generated from a synthetic reservoir model. Our aim is to invert directly for rock facies and porosity of the target reservoir zone. We solve this inverse problem using a Markov chain Monte Carlo (McMC) method to handle the nonlinear......, multi-step forward model (rock physics and seismology) and to provide realistic estimates of uncertainties. To generate realistic models which represent samples of the prior distribution, and to overcome the high computational demand, we reduce the search space utilizing an algorithm drawn from...

  18. Downscaling SMAP Soil Moisture Using Geoinformation Data and Geostatistics

    Science.gov (United States)

    Xu, Y.; Wang, L.

    2017-12-01

    Soil moisture is important for agricultural and hydrological studies. However, ground truth soil moisture data for wide area is difficult to achieve. Microwave remote sensing such as Soil Moisture Active Passive (SMAP) can offer a solution for wide coverage. However, existing global soil moisture products only provide observations at coarse spatial resolutions, which often limit their applications in regional agricultural and hydrological studies. This paper therefore aims to generate fine scale soil moisture information and extend soil moisture spatial availability. A statistical downscaling scheme is presented that incorporates multiple fine scale geoinformation data into the downscaling of coarse scale SMAP data in the absence of ground measurement data. Geoinformation data related to soil moisture patterns including digital elevation model (DEM), land surface temperature (LST), land use and normalized difference vegetation index (NDVI) at a fine scale are used as auxiliary environmental variables for downscaling SMAP data. Generalized additive model (GAM) and regression tree are first conducted to derive statistical relationships between SMAP data and auxiliary geoinformation data at an original coarse scale, and residuals are then downscaled to a finer scale via area-to-point kriging (ATPK) by accounting for the spatial correlation information of the input residuals. The results from standard validation scores as well as the triple collocation (TC) method against soil moisture in-situ measurements show that the downscaling method can significantly improve the spatial details of SMAP soil moisture while maintain the accuracy.

  19. Assessing Landscape-Scale Soil Moisture Distribution Using Auxiliary Sensing Technologies and Multivariate Geostatistics

    Science.gov (United States)

    Landrum, C.; Castrignanò, A.; Mueller, T.; Zourarakis, D.; Zhu, J.

    2013-12-01

    It is important to assess soil moisture to develop strategies to better manage its availability and use. At the landscape scale, soil moisture distribution derives from an integration of hydrologic, pedologic and geomorphic processes that cause soil moisture variability (SMV) to be time, space, and scale-dependent. Traditional methods to assess SMV at this scale are often costly, labor intensive, and invasive, which can lead to inadequate sampling density and spatial coverage. Fusing traditional sampling techniques with georeferenced auxiliary sensing technologies, such as geoelectric sensing and LiDAR, provide an alternative approach. Because geoelectric and LiDAR measurements are sensitive to soil properties and terrain features that affect soil moisture variation, they are often employed as auxiliary measures to support less dense direct sampling. Georeferenced proximal sensing acquires rapid, real-time, high resolution data over large spatial extents that is enriched with spatial, temporal and scale-dependent information. Data fusion becomes important when proximal sensing is used in tandem with more sparse direct sampling. Multicollocated factorial cokriging (MFC) is one technique of multivariate geostatistics to fuse multiple data sources collected at different sampling scales to study the spatial characteristics of environmental properties. With MFC sparse soil observations are supported by more densely sampled auxiliary attributes to produce more consistent spatial descriptions of scale-dependent parameters affecting SMV. This study uses high resolution geoelectric and LiDAR data as auxiliary measures to support direct soil sampling (n=127) over a 40 hectare Central Kentucky (USA) landscape. Shallow and deep apparent electrical resistivity (ERa) were measured using a Veris 3100 in tandem with soil moisture sampling on three separate dates with ascending soil moisture contents ranging from plant wilting point to field capacity. Terrain features were produced

  20. Characterizing regional soil mineral composition using spectroscopyand geostatistics

    Science.gov (United States)

    Mulder, V.L.; de Bruin, S.; Weyermann, J.; Kokaly, Raymond F.; Schaepman, M.E.

    2013-01-01

    This work aims at improving the mapping of major mineral variability at regional scale using scale-dependent spatial variability observed in remote sensing data. Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data and statistical methods were combined with laboratory-based mineral characterization of field samples to create maps of the distributions of clay, mica and carbonate minerals and their abundances. The Material Identification and Characterization Algorithm (MICA) was used to identify the spectrally-dominant minerals in field samples; these results were combined with ASTER data using multinomial logistic regression to map mineral distributions. X-ray diffraction (XRD)was used to quantify mineral composition in field samples. XRD results were combined with ASTER data using multiple linear regression to map mineral abundances. We testedwhether smoothing of the ASTER data to match the scale of variability of the target sample would improve model correlations. Smoothing was donewith Fixed Rank Kriging (FRK) to represent the mediumand long-range spatial variability in the ASTER data. Stronger correlations resulted using the smoothed data compared to results obtained with the original data. Highest model accuracies came from using both medium and long-range scaled ASTER data as input to the statistical models. High correlation coefficients were obtained for the abundances of calcite and mica (R2 = 0.71 and 0.70, respectively). Moderately-high correlation coefficients were found for smectite and kaolinite (R2 = 0.57 and 0.45, respectively). Maps of mineral distributions, obtained by relating ASTER data to MICA analysis of field samples, were found to characterize major soil mineral variability (overall accuracies for mica, smectite and kaolinite were 76%, 89% and 86% respectively). The results of this study suggest that the distributions of minerals and their abundances derived using FRK-smoothed ASTER data more closely match the spatial

  1. Hydrology and Geostatistics of a Vermont, USA Kettlehole Peatland

    Science.gov (United States)

    Mouser, Paula J.; Hession, W. Cully; Rizzo, Donna M.; Gotelli, Nicholas J.

    2005-01-01

    The ability to predict the response of peatland ecosystems to hydrologic changes is imperative for successful conservation and remediation efforts. We studied a 1.25-ha Vermont kettlehole bog for one year (September 2001-October 2002) to identify hydrologic controls, temporal and spatial variability in flow regimes, and to link hydrologic processes to density of the carnivorous plant ( Sarracenia purpurea), an ombrotrophic bog specialist. Using a spatial array of nested piezometers, we measured surface and subsurface flow in shallow peat and surrounding mineral soil. Our unique sampling array was based on a repeated measures factorial design with: (1) incremental distances from a central kettlehole pond; (2) equal distances between piezometers; and (3) at three depths from the peat surface. Local flow patterns in the peat were controlled by snowpack storage during winter and spring months and by evapotranspiration and pond water elevation during summer and fall months. Hydraulic head values showed a local reversal within the peat during spring months which was reflected in higher chemical constituent concentrations in these wells. On a regional scale, higher permeable soils diverted groundwater beneath the peatland to a nearby wetland complex. Horizontal water gradient magnitudes were larger in zones where the peatland was perched above regional groundwater and smaller in zones where a hydraulic connection existed between the peatland and the regional groundwater. The density of pitcher plants ( S. purpurea) is strongly correlated to the distance from a central pond, [Fe 3+], [Na +], [Cl -], and [SO42-]. The pH, conductivity, and [Ca 2+] had significant effects of depth and time with horizontal distance correlations between 20 and 26 m. The pH samples had temporal correlations between 27 and 79 days. The link between pitcher plants and ion chemistry; significant effects of peatland chemistry on distance, depth, and time; and spatial and temporal correlations are

  2. Study design considerations in evaluating environmental impacts

    Science.gov (United States)

    Stan T. Lebow; Paul A. Cooper; Patricia Lebow

    2006-01-01

    The purpose of this chapter is to make the reader aware of how choices in study parameters may influence the outcome of treated-wood environmental impact evaluations. Evaluation of the leaching and environmental accumulation of preservatives from treated wood is a complex process. and many factors can influence the results of such studies. In laboratory studies, the...

  3. A comparison of geostatistically-based inverse techniques for use in performance assessment analysis at the WIPP site results from test case No. 1

    International Nuclear Information System (INIS)

    Zimmerman, D.A.; Gallegos, D.P.

    1993-01-01

    The groundwater flow pathway in the Culebra Dolomite aquifer at the Waste Isolation Pilot Plant (WIPP) has been identified as a potentially important pathway for radionuclide migration to the accessible environment. Consequently, uncertainties in the models used to described flow and transport in the Culebra need to be addressed. A 'Geostatistics Test Problem' is being developed as a highly complex synthetic data set; the intent is for the ensemble of these data sets span the range of possible conceptual models of groundwater flow at the WIPP site. The Test Problem analysis approach is to use a comparison of the probabilistic groundwater travel time (GWTT) estimates produced by each technique as the basis for the evaluation. Participants are given observations of head and transmissivity and are asked to develop stochastic models of groundwater flow for the synthetic system. Cumulative distribution functions (CDFs) of groundwater flow (computed via particle tracking) are constructed using the head and transmissivity data generated through the application of each technique; one semi-analytical method generates the CDFs of groundwater flow directly. This paper describes the results from Test Case No 1. Of the five techniques compared, those based on the linearized form of the groundwater flow equation exhibited less bias and less spread in their GWTT distribution functions; the semi-analytical method had the least bias. While the results are not sufficient to make generalizations about which techniques may be better suited for the WIPP PA (only one test case has been exercised), analysis of the data from this test case provides some indication about the relative importance of other aspects of the flow modeling (besides inverse method or geostatistical approach) in PA. These ancillary analyses examine the effect of gridding and the effect of boundary conditions on the groundwater travel time estimates

  4. Geostatistical approach for management of soil nutrients with special emphasis on different forms of potassium considering their spatial variation in intensive cropping system of West Bengal, India.

    Science.gov (United States)

    Chatterjee, Sourov; Santra, Priyabrata; Majumdar, Kaushik; Ghosh, Debjani; Das, Indranil; Sanyal, S K

    2015-04-01

    A large part of precision agriculture research in the developing countries is devoted towards precision nutrient management aspects. This has led to better economics and efficiency of nutrient use with off-farm advantages of environmental security. The keystone of precision nutrient management is analysis and interpretation of spatial variability of soils by establishing management zones. In this study, spatial variability of major soil nutrient contents was evaluated in the Ghoragacha village of North 24 Parganas district of West Bengal, India. Surface soil samples from 100 locations, covering different cropping systems of the village, was collected from 0 to 15 cm depth using 100×100 m grid system and analyzed in the laboratory to determine organic carbon (OC), available nitrogen (N), phosphorus (P), and potassium (K) contents of the soil as well as its water-soluble K (KWS), exchangeable K (KEX), and non-exchangeable forms of K (KNEX). Geostatistical analyses were performed to determine the spatial variation structure of each nutrient content within the village, followed by the generation of surface maps through kriging. Four commonly used semivariogram models, i.e., spherical, exponential, Gaussian, and linear models were fitted to each soil property, and the best one was used to prepare surface maps through krigging. Spherical model was found the best for available N and P contents, while linear and exponential model was the best for OC and available K, and for KWS and KNEK, Gausian model was the best. Surface maps of nutrient contents showed that N content (129-195 kg ha(-1)) was the most limiting factor throughout the village, while P status was generally very high ( 10-678 kg ha(-1)) in the soils of the present village. Among the different soil K fractions, KWS registered the maximum variability (CV 75%), while the remaining soil K fractions showed moderate to high variation. Interestingly, KNEX content also showed high variability, which essentially

  5. A novel geotechnical/geostatistical approach for exploration and production of natural gas from multiple geologic strata, Phase 1. Volume 2, Geology and engineering

    Energy Technology Data Exchange (ETDEWEB)

    Overbey, W.K. Jr.; Reeves, T.K.; Salamy, S.P.; Locke, C.D.; Johnson, H.R.; Brunk, R.; Hawkins, L. [BDM Engineering Services Co., Morgantown, WV (United States)

    1991-05-01

    This research program has been designed to develop and verify a unique geostatistical approach for finding natural gas resources. The project has been conducted by Beckley College, Inc., and BDM Engineering Services Company (BDMESC) under contract to the US Department of Energy (DOE), Morgantown Energy Technology Center (METC). This section, Volume II, contains a detailed discussion of the methodology used and the geological and production information collected and analyzed for this study. A companion document, Volume 1, provides an overview of the program, technique and results of the study. In combination, Volumes I and II cover the completion of the research undertaken under Phase I of this DOE project, which included the identification of five high-potential sites for natural gas production on the Eccles Quadrangle, Raleigh County, West Virginia. Each of these sites was selected for its excellent potential for gas production from both relatively shallow coalbeds and the deeper, conventional reservoir formations.

  6. Regional soil erosion assessment based on a sample survey and geostatistics

    Science.gov (United States)

    Yin, Shuiqing; Zhu, Zhengyuan; Wang, Li; Liu, Baoyuan; Xie, Yun; Wang, Guannan; Li, Yishan

    2018-03-01

    Soil erosion is one of the most significant environmental problems in China. From 2010 to 2012, the fourth national census for soil erosion sampled 32 364 PSUs (Primary Sampling Units, small watersheds) with the areas of 0.2-3 km2. Land use and soil erosion controlling factors including rainfall erosivity, soil erodibility, slope length, slope steepness, biological practice, engineering practice, and tillage practice for the PSUs were surveyed, and the soil loss rate for each land use in the PSUs was estimated using an empirical model, the Chinese Soil Loss Equation (CSLE). Though the information collected from the sample units can be aggregated to estimate soil erosion conditions on a large scale; the problem of estimating soil erosion condition on a regional scale has not been addressed well. The aim of this study is to introduce a new model-based regional soil erosion assessment method combining a sample survey and geostatistics. We compared seven spatial interpolation models based on the bivariate penalized spline over triangulation (BPST) method to generate a regional soil erosion assessment from the PSUs. Shaanxi Province (3116 PSUs) in China was selected for the comparison and assessment as it is one of the areas with the most serious erosion problem. Ten-fold cross-validation based on the PSU data showed the model assisted by the land use, rainfall erosivity factor (R), soil erodibility factor (K), slope steepness factor (S), and slope length factor (L) derived from a 1 : 10 000 topography map is the best one, with the model efficiency coefficient (ME) being 0.75 and the MSE being 55.8 % of that for the model assisted by the land use alone. Among four erosion factors as the covariates, the S factor contributed the most information, followed by K and L factors, and R factor made almost no contribution to the spatial estimation of soil loss. The LS factor derived from 30 or 90 m Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) data

  7. Monte Carlo full-waveform inversion of crosshole GPR data using multiple-point geostatistical a priori information

    DEFF Research Database (Denmark)

    Cordua, Knud Skou; Hansen, Thomas Mejer; Mosegaard, Klaus

    2012-01-01

    We present a general Monte Carlo full-waveform inversion strategy that integrates a priori information described by geostatistical algorithms with Bayesian inverse problem theory. The extended Metropolis algorithm can be used to sample the a posteriori probability density of highly nonlinear inve...

  8. Evaluating Evaluation Systems: Policy Levers and Strategies for Studying Implementation of Educator Evaluation. Policy Snapshot

    Science.gov (United States)

    Matlach, Lauren

    2015-01-01

    Evaluation studies can provide feedback on implementation, support continuous improvement, and increase understanding of evaluation systems' impact on teaching and learning. Despite the importance of educator evaluation studies, states often need support to prioritize and fund them. Successful studies require expertise, time, and a shared…

  9. Local Geostatistical Models and Big Data in Hydrological and Ecological Applications

    Science.gov (United States)

    Hristopulos, Dionissios

    2015-04-01

    The advent of the big data era creates new opportunities for environmental and ecological modelling but also presents significant challenges. The availability of remote sensing images and low-cost wireless sensor networks implies that spatiotemporal environmental data to cover larger spatial domains at higher spatial and temporal resolution for longer time windows. Handling such voluminous data presents several technical and scientific challenges. In particular, the geostatistical methods used to process spatiotemporal data need to overcome the dimensionality curse associated with the need to store and invert large covariance matrices. There are various mathematical approaches for addressing the dimensionality problem, including change of basis, dimensionality reduction, hierarchical schemes, and local approximations. We present a Stochastic Local Interaction (SLI) model that can be used to model local correlations in spatial data. SLI is a random field model suitable for data on discrete supports (i.e., regular lattices or irregular sampling grids). The degree of localization is determined by means of kernel functions and appropriate bandwidths. The strength of the correlations is determined by means of coefficients. In the "plain vanilla" version the parameter set involves scale and rigidity coefficients as well as a characteristic length. The latter determines in connection with the rigidity coefficient the correlation length of the random field. The SLI model is based on statistical field theory and extends previous research on Spartan spatial random fields [2,3] from continuum spaces to explicitly discrete supports. The SLI kernel functions employ adaptive bandwidths learned from the sampling spatial distribution [1]. The SLI precision matrix is expressed explicitly in terms of the model parameter and the kernel function. Hence, covariance matrix inversion is not necessary for parameter inference that is based on leave-one-out cross validation. This property

  10. Comparison of ArcGIS and SAS Geostatistical Analyst to Estimate Population-Weighted Monthly Temperature for US Counties.

    Science.gov (United States)

    Xiaopeng, Q I; Liang, Wei; Barker, Laurie; Lekiachvili, Akaki; Xingyou, Zhang

    Temperature changes are known to have significant impacts on human health. Accurate estimates of population-weighted average monthly air temperature for US counties are needed to evaluate temperature's association with health behaviours and disease, which are sampled or reported at the county level and measured on a monthly-or 30-day-basis. Most reported temperature estimates were calculated using ArcGIS, relatively few used SAS. We compared the performance of geostatistical models to estimate population-weighted average temperature in each month for counties in 48 states using ArcGIS v9.3 and SAS v 9.2 on a CITGO platform. Monthly average temperature for Jan-Dec 2007 and elevation from 5435 weather stations were used to estimate the temperature at county population centroids. County estimates were produced with elevation as a covariate. Performance of models was assessed by comparing adjusted R 2 , mean squared error, root mean squared error, and processing time. Prediction accuracy for split validation was above 90% for 11 months in ArcGIS and all 12 months in SAS. Cokriging in SAS achieved higher prediction accuracy and lower estimation bias as compared to cokriging in ArcGIS. County-level estimates produced by both packages were positively correlated (adjusted R 2 range=0.95 to 0.99); accuracy and precision improved with elevation as a covariate. Both methods from ArcGIS and SAS are reliable for U.S. county-level temperature estimates; However, ArcGIS's merits in spatial data pre-processing and processing time may be important considerations for software selection, especially for multi-year or multi-state projects.

  11. Study on team evaluation. Team process model for team evaluation

    International Nuclear Information System (INIS)

    Sasou Kunihide; Ebisu, Mitsuhiro; Hirose, Ayako

    2004-01-01

    Several studies have been done to evaluate or improve team performance in nuclear and aviation industries. Crew resource management is the typical example. In addition, team evaluation recently gathers interests in other teams of lawyers, medical staff, accountants, psychiatrics, executive, etc. However, the most evaluation methods focus on the results of team behavior that can be observed through training or actual business situations. What is expected team is not only resolving problems but also training younger members being destined to lead the next generation. Therefore, the authors set the final goal of this study establishing a series of methods to evaluate and improve teams inclusively such as decision making, motivation, staffing, etc. As the first step, this study develops team process model describing viewpoints for the evaluation. The team process is defined as some kinds of power that activate or inactivate competency of individuals that is the components of team's competency. To find the team process, the authors discussed the merits of team behavior with the experienced training instructors and shift supervisors of nuclear/thermal power plants. The discussion finds four team merits and many components to realize those team merits. Classifying those components into eight groups of team processes such as 'Orientation', 'Decision Making', 'Power and Responsibility', 'Workload Management', 'Professional Trust', 'Motivation', 'Training' and 'staffing', the authors propose Team Process Model with two to four sub processes in each team process. In the future, the authors will develop methods to evaluate some of the team processes for nuclear/thermal power plant operation teams. (author)

  12. Application of Geostatistics to the resolution of structural problems in homogeneous rocky massifs

    International Nuclear Information System (INIS)

    Lucero Michaut, H.N.

    1985-01-01

    The nature and possibilities of application of intrinsic functions to the structural research and the delimitation of the areas of influence in an ore deposit are briefly described. Main models to which the different distributions may be assimilated: 'logarithmic' and 'linear' among those with no sill value, and on the other hand, 'spherical', 'exponential' and 'gaussian' among those having a sill level, which allows the establishment of a range value liable to separate the field of independent samples from that of non-independent ones are shown. Thereafter as an original contribution to applied geostatistics the autor postulates 1) the application of the 'fracturing rank' as a regionalized variable after verifying its validity through strict probabilistic methodologies, and 2) a methodological extension of the conventional criterion of 'rock quality designation' to the analysis of the quality and degree of structural discontinuity in the rock surface. Finally, some examples are given of these applications. (M.E.L.) [es

  13. Geostatistical exploration of dataset assessing the heavy metal contamination in Ewekoro limestone, Southwestern Nigeria

    Directory of Open Access Journals (Sweden)

    Kehinde D. Oyeyemi

    2017-10-01

    Full Text Available The dataset for this article contains geostatistical analysis of heavy metals contamination from limestone samples collected from Ewekoro Formation in the eastern Dahomey basin, Ogun State Nigeria. The samples were manually collected and analysed using Microwave Plasma Atomic Absorption Spectrometer (MPAS. Analysis of the twenty different samples showed different levels of heavy metals concentration. The analysed nine elements are Arsenic, Mercury, Cadmium, Cobalt, Chromium, Nickel, Lead, Vanadium and Zinc. Descriptive statistics was used to explore the heavy metal concentrations individually. Pearson, Kendall tau and Spearman rho correlation coefficients was used to establish the relationships among the elements and the analysis of variance showed that there is a significant difference in the mean distribution of the heavy metals concentration within and between the groups of the 20 samples analysed. The dataset can provide insights into the health implications of the contaminants especially when the mean concentration levels of the heavy metals are compared with recommended regulatory limit concentration.

  14. Implementation of the Iterative Proportion Fitting Algorithm for Geostatistical Facies Modeling

    International Nuclear Information System (INIS)

    Li Yupeng; Deutsch, Clayton V.

    2012-01-01

    In geostatistics, most stochastic algorithm for simulation of categorical variables such as facies or rock types require a conditional probability distribution. The multivariate probability distribution of all the grouped locations including the unsampled location permits calculation of the conditional probability directly based on its definition. In this article, the iterative proportion fitting (IPF) algorithm is implemented to infer this multivariate probability. Using the IPF algorithm, the multivariate probability is obtained by iterative modification to an initial estimated multivariate probability using lower order bivariate probabilities as constraints. The imposed bivariate marginal probabilities are inferred from profiles along drill holes or wells. In the IPF process, a sparse matrix is used to calculate the marginal probabilities from the multivariate probability, which makes the iterative fitting more tractable and practical. This algorithm can be extended to higher order marginal probability constraints as used in multiple point statistics. The theoretical framework is developed and illustrated with estimation and simulation example.

  15. Geostatistical three-dimensional modeling of oolite shoals, St. Louis Limestone, southwest Kansas

    Science.gov (United States)

    Qi, L.; Carr, T.R.; Goldstein, R.H.

    2007-01-01

    In the Hugoton embayment of southwestern Kansas, reservoirs composed of relatively thin (oil. The geometry and distribution of oolitic deposits control the heterogeneity of the reservoirs, resulting in exploration challenges and relatively low recovery. Geostatistical three-dimensional (3-D) models were constructed to quantify the geometry and spatial distribution of oolitic reservoirs, and the continuity of flow units within Big Bow and Sand Arroyo Creek fields. Lithofacies in uncored wells were predicted from digital logs using a neural network. The tilting effect from the Laramide orogeny was removed to construct restored structural surfaces at the time of deposition. Well data and structural maps were integrated to build 3-D models of oolitic reservoirs using stochastic simulations with geometry data. Three-dimensional models provide insights into the distribution, the external and internal geometry of oolitic deposits, and the sedimentologic processes that generated reservoir intervals. The structural highs and general structural trend had a significant impact on the distribution and orientation of the oolitic complexes. The depositional pattern and connectivity analysis suggest an overall aggradation of shallow-marine deposits during pulses of relative sea level rise followed by deepening near the top of the St. Louis Limestone. Cemented oolitic deposits were modeled as barriers and baffles and tend to concentrate at the edge of oolitic complexes. Spatial distribution of porous oolitic deposits controls the internal geometry of rock properties. Integrated geostatistical modeling methods can be applicable to other complex carbonate or siliciclastic reservoirs in shallow-marine settings. Copyright ?? 2007. The American Association of Petroleum Geologists. All rights reserved.

  16. Optimizing Usability Studies by Complementary Evaluation Methods

    NARCIS (Netherlands)

    Schmettow, Martin; Bach, Cedric; Scapin, Dominique

    2014-01-01

    This paper examines combinations of complementary evaluation methods as a strategy for efficient usability problem discovery. A data set from an earlier study is re-analyzed, involving three evaluation methods applied to two virtual environment applications. Results of a mixed-effects logistic

  17. Characterizing groundwater quality ranks for drinking purposes in Sylhet district, Bangladesh, using entropy method, spatial autocorrelation index, and geostatistics.

    Science.gov (United States)

    Islam, Abu Reza Md Towfiqul; Ahmed, Nasir; Bodrud-Doza, Md; Chu, Ronghao

    2017-12-01

    Drinking water is susceptible to the poor quality of contaminated water affecting the health of humans. Thus, it is an essential study to investigate factors affecting groundwater quality and its suitability for drinking uses. In this paper, the entropy theory, multivariate statistics, spatial autocorrelation index, and geostatistics are applied to characterize groundwater quality and its spatial variability in the Sylhet district of Bangladesh. A total of 91samples have been collected from wells (e.g., shallow, intermediate, and deep tube wells at 15-300-m depth) from the study area. The results show that NO 3 - , then SO 4 2- , and As are the most contributed parameters influencing the groundwater quality according to the entropy theory. The principal component analysis (PCA) and correlation coefficient also confirm the results of the entropy theory. However, Na + has the highest spatial autocorrelation and the most entropy, thus affecting the groundwater quality. Based on the entropy-weighted water quality index (EWQI) and groundwater quality index (GWQI) classifications, it is observed that 60.45 and 53.86% of water samples are classified as having an excellent to good qualities, while the remaining samples vary from medium to extremely poor quality domains for drinking purposes. Furthermore, the EWQI classification provides the more reasonable results than GWQIs due to its simplicity, accuracy, and ignoring of artificial weight. A Gaussian semivariogram model has been chosen to the best fit model, and groundwater quality indices have a weak spatial dependence, suggesting that both geogenic and anthropogenic factors play a pivotal role in spatial heterogeneity of groundwater quality oscillations.

  18. Using the Direct Sampling Multiple-Point Geostatistical Method for Filling Gaps in Landsat 7 ETM+ SLC-off Imagery

    KAUST Repository

    Yin, Gaohong

    2016-05-01

    Since the failure of the Scan Line Corrector (SLC) instrument on Landsat 7, observable gaps occur in the acquired Landsat 7 imagery, impacting the spatial continuity of observed imagery. Due to the highly geometric and radiometric accuracy provided by Landsat 7, a number of approaches have been proposed to fill the gaps. However, all proposed approaches have evident constraints for universal application. The main issues in gap-filling are an inability to describe the continuity features such as meandering streams or roads, or maintaining the shape of small objects when filling gaps in heterogeneous areas. The aim of the study is to validate the feasibility of using the Direct Sampling multiple-point geostatistical method, which has been shown to reconstruct complicated geological structures satisfactorily, to fill Landsat 7 gaps. The Direct Sampling method uses a conditional stochastic resampling of known locations within a target image to fill gaps and can generate multiple reconstructions for one simulation case. The Direct Sampling method was examined across a range of land cover types including deserts, sparse rural areas, dense farmlands, urban areas, braided rivers and coastal areas to demonstrate its capacity to recover gaps accurately for various land cover types. The prediction accuracy of the Direct Sampling method was also compared with other gap-filling approaches, which have been previously demonstrated to offer satisfactory results, under both homogeneous area and heterogeneous area situations. Studies have shown that the Direct Sampling method provides sufficiently accurate prediction results for a variety of land cover types from homogeneous areas to heterogeneous land cover types. Likewise, it exhibits superior performances when used to fill gaps in heterogeneous land cover types without input image or with an input image that is temporally far from the target image in comparison with other gap-filling approaches.

  19. Quantifying the exposure of humans and the environment to oil pollution in the Niger Delta using advanced geostatistical techniques.

    Science.gov (United States)

    Obida, Christopher B; Alan Blackburn, G; Duncan Whyatt, J; Semple, Kirk T

    2018-02-01

    The Niger Delta is one of the largest oil producing regions of the world. Large numbers and volumes of oil spills have been reported in this region. What has not been quantified is the putative exposure of humans and/or the environment to this hydrocarbon pollution. In this novel study, advanced geostatistical techniques were applied to an extensive database of oil spill incidents from 2007 to 2015. The aims were to (i) identify and analyse spill hotspots along the oil pipeline network and (ii) estimate the exposure of the hydrocarbon pollution to the human population and the environment within the Niger Delta. Over the study period almost 90millionlitres of oil were released. Approximately 29% of the human population living in proximity to the pipeline network has been potentially exposed to oil contamination, of which 565,000 people live within high or very high spill intensity sectors. Over 1000km 2 of land has been contaminated by oil pollution, with broadleaved forest, mangroves and agricultural land the most heavily impacted land cover types. Proximity to the coast, roads and cities are the strongest spatial factors contributing to spill occurrence, which largely determine the accessibility of sites for pipeline sabotage and oil theft. Overall, the findings demonstrate the high levels of environmental and human exposure to hydrocarbon pollutants in the Niger Delta. These results provide evidence with which to spatially target interventions to reduce future spill incidents and mitigate the impacts of previous spills on human communities and ecosystem health. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Multivariate geostatistical analysis and source identification of heavy metals in the sediment of Poyang Lake in China.

    Science.gov (United States)

    Dai, Lijun; Wang, Lingqing; Li, Lianfang; Liang, Tao; Zhang, Yongyong; Ma, Chuanxin; Xing, Baoshan

    2018-04-15

    Heavy metals in lake sediment have become a great concern because their remobilization has frequently occurred under hydrodynamic disturbance in shallow lakes. In this study, heavy metals (Cr, Cu, Cd, Pb, and Zn) concentrations in the surface and core sediments of the largest freshwater lake in China, Poyang Lake, were investigated. Geostatistical prediction maps of heavy metals distribution in the surface sediment were completed as well as further data mining. Based on the prediction maps, the ranges of Cr, Cu, Cd, Pb, and Zn concentrations in the surface sediments of the entire lake were 96.2-175.2, 38.3-127.6, 0.2-2.3, 22.5-77.4, and 72.3-254.4mg/kg, respectively. A self-organizing map (SOM) was applied to find the inner element relation of heavy metals in the sediment cores. K-means clustering of the self-organizing map was also completed to define the Euclidian distance of heavy metals in the sediment cores. The geoaccumulation index (I geo ) for Poyang Lake indicated a varying degree of heavy metal contamination in the surface sediment, especially for Cu. The heavy metal contamination in the sediment profiles had similar pollution levels as those of surface sediment, except for Cd. Correlation matrix mapping and principal component analysis (PCA) were used to support the idea that Cr, Pb, and Zn may be mainly derived from both lithogenic and human activities, such as atmospheric and river inflow transportation, whereas Cu and Cd may be mainly contributed from anthropogenic sources, such as mining activities and fertilizer application. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Improved hydrological model parametrization for climate change impact assessment under data scarcity - The potential of field monitoring techniques and geostatistics.

    Science.gov (United States)

    Meyer, Swen; Blaschek, Michael; Duttmann, Rainer; Ludwig, Ralf

    2016-02-01

    According to current climate projections, Mediterranean countries are at high risk for an even pronounced susceptibility to changes in the hydrological budget and extremes. These changes are expected to have severe direct impacts on the management of water resources, agricultural productivity and drinking water supply. Current projections of future hydrological change, based on regional climate model results and subsequent hydrological modeling schemes, are very uncertain and poorly validated. The Rio Mannu di San Sperate Basin, located in Sardinia, Italy, is one test site of the CLIMB project. The Water Simulation Model (WaSiM) was set up to model current and future hydrological conditions. The availability of measured meteorological and hydrological data is poor as it is common for many Mediterranean catchments. In this study we conducted a soil sampling campaign in the Rio Mannu catchment. We tested different deterministic and hybrid geostatistical interpolation methods on soil textures and tested the performance of the applied models. We calculated a new soil texture map based on the best prediction method. The soil model in WaSiM was set up with the improved new soil information. The simulation results were compared to standard soil parametrization. WaSiMs was validated with spatial evapotranspiration rates using the triangle method (Jiang and Islam, 1999). WaSiM was driven with the meteorological forcing taken from 4 different ENSEMBLES climate projections for a reference (1971-2000) and a future (2041-2070) times series. The climate change impact was assessed based on differences between reference and future time series. The simulated results show a reduction of all hydrological quantities in the future in the spring season. Furthermore simulation results reveal an earlier onset of dry conditions in the catchment. We show that a solid soil model setup based on short-term field measurements can improve long-term modeling results, which is especially important

  2. A geostatistical analysis of the association between armed conflicts and Plasmodium falciparum malaria in Africa, 1997-2010.

    Science.gov (United States)

    Sedda, Luigi; Qi, Qiuyin; Tatem, Andrew J

    2015-12-16

    The absence of conflict in a country has been cited as a crucial factor affecting the operational feasibility of achieving malaria control and elimination, yet mixed evidence exists on the influence that conflicts have had on malaria transmission. Over the past two decades, Africa has seen substantial numbers of armed conflicts of varying length and scale, creating conditions that can disrupt control efforts and impact malaria transmission. However, very few studies have quantitatively assessed the associations between conflicts and malaria transmission, particularly in a consistent way across multiple countries. In this analysis an explicit geostatistical, autoregressive, mixed model is employed to quantitatively assess the association between conflicts and variations in Plasmodium falciparum parasite prevalence across a 13-year period in sub-Saharan Africa. Analyses of geolocated, malaria prevalence survey variations against armed conflict data in general showed a wide, but short-lived impact of conflict events geographically. The number of countries with decreased P. falciparum parasite prevalence (17) is larger than the number of countries with increased transmission (12), and notably, some of the countries with the highest transmission pre-conflict were still found with lower transmission post-conflict. For four countries, there were no significant changes in parasite prevalence. Finally, distance from conflicts, duration of conflicts, violence of conflict, and number of conflicts were significant components in the model explaining the changes in P. falciparum parasite rate. The results suggest that the maintenance of intervention coverage and provision of healthcare in conflict situations to protect vulnerable populations can maintain gains in even the most difficult of circumstances, and that conflict does not represent a substantial barrier to elimination goals.

  3. Geostatistics project of the National Uranium Resources Evaluation Program. Progress report, October 1978--March 1979

    International Nuclear Information System (INIS)

    Beckman, R.J.; Bement, T.R.; Campbell, K.; Howell, J.S.; Wecksung, G.W.; Whitemann, D.E.

    1979-01-01

    During the period covered by this report, research was concentrated on multivariate approaches to the analysis of aerial radiometric data. Two aspects of principal components analysis were the subjects of two publications. The procedures recommended for linear discriminant analysis were revised. Progress was made in overlaying LANDSAT data with aerial radiometric data from the Lubbock quadrangle. Some preliminary results from principal components analysis of the Wind River data were obtained

  4. Evaluation of Groundwater Quality Indices of Mashhad Plain using Geostatistics and GIS Techniques

    Directory of Open Access Journals (Sweden)

    Mohammadreza Yazdani

    2017-11-01

    The outcomes illustrate that the qualitative conditions of underground water resources, particularly in TDS and TH are in the inappropriate condition in the southern parts of Mashhad. It is related to the high population density and the lack of proper drainage. It is needed to restrict over exploitation of groundwater resources in critical hot spots, along with defining alternative safe water sources for urban consumption.

  5. Geostatistics project of the national uranium resource evaluation program. Progress report, October 1979-March 1980

    International Nuclear Information System (INIS)

    Campbell, K.; Bement, T.R.; Howell, J.A.; Beckman, R.J.; Jackson, K.; Buslee, P.

    1980-08-01

    During the period covered by this report, the authors investigated the serial properties of aerial radiometric data. Results were applied to the choice of minimum segment width in the maximum variance segments algorithm and to the use of aerial radiometric data in the design of ground sampling experiments. The report also presents the results of a comparison of normal and lognormal percentile estimation techniques. Twenty-two quadrangles are being analyzed in the search for a uranium favorability index. Computer codes developed during this investigation have been provided to the Bendix Field Engineering Corporation in Grand Junction, Colorado

  6. Time-Lapse Analysis of Methane Quantity in the Mary Lee Group of Coal Seams Using Filter-Based Multiple-Point Geostatistical Simulation.

    Science.gov (United States)

    Karacan, C Özgen; Olea, Ricardo A

    2013-08-01

    Coal seam degasification and its success are important for controlling methane, and thus for the health and safety of coal miners. During the course of degasification, properties of coal seams change. Thus, the changes in coal reservoir conditions and in-place gas content as well as methane emission potential into mines should be evaluated by examining time-dependent changes and the presence of major heterogeneities and geological discontinuities in the field. In this work, time-lapsed reservoir and fluid storage properties of the New Castle coal seam, Mary Lee/Blue Creek seam, and Jagger seam of Black Warrior Basin, Alabama, were determined from gas and water production history matching and production forecasting of vertical degasification wellbores. These properties were combined with isotherm and other important data to compute gas-in-place (GIP) and its change with time at borehole locations. Time-lapsed training images (TIs) of GIP and GIP difference corresponding to each coal and date were generated by using these point-wise data and Voronoi decomposition on the TI grid, which included faults as discontinuities for expansion of Voronoi regions. Filter-based multiple-point geostatistical simulations, which were preferred in this study due to anisotropies and discontinuities in the area, were used to predict time-lapsed GIP distributions within the study area. Performed simulations were used for mapping spatial time-lapsed methane quantities as well as their uncertainties within the study area. The systematic approach presented in this paper is the first time in literature that history matching, TIs of GIPs and filter simulations are used for degasification performance evaluation and for assessing GIP for mining safety. Results from this study showed that using production history matching of coalbed methane wells to determine time-lapsed reservoir data could be used to compute spatial GIP and representative GIP TIs generated through Voronoi decomposition

  7. Optimal design of sampling and mapping schemes in the radiometric exploration of Chipilapa, El Salvador (Geo-statistics)

    International Nuclear Information System (INIS)

    Balcazar G, M.; Flores R, J.H.

    1992-01-01

    As part of the knowledge about the radiometric surface exploration, carried out in the geothermal field of Chipilapa, El Salvador, its were considered the geo-statistical parameters starting from the calculated variogram of the field data, being that the maxim distance of correlation of the samples in 'radon' in the different observation addresses (N-S, E-W, N W-S E, N E-S W), it was of 121 mts for the monitoring grill in future prospectus in the same area. Being derived of it an optimization (minimum cost) in the spacing of the field samples by means of geo-statistical techniques, without losing the detection of the anomaly. (Author)

  8. Geostatistical modeling of a fluviodeltaic reservoir in the Huyapari Field, Hamaca area, in the Faja Petrolifera del Orinoco, Venezuela

    Energy Technology Data Exchange (ETDEWEB)

    De Ascencao, Erika M.; Munckton, Toni; Digregorio, Ricardo [Petropiar (Venezuela)

    2011-07-01

    The Huyapari field, situated within the Faja Petrolifera del Orinoco (FPO) of Venezuela presents unique problems in terms of modeling. This field is spread over a wide area and is therefore subject to variable oil quality and complex fluvial facies architecture. Ameriven and PDVSA have been working on characterizing the ld's reservoirs in this field since 2000 and the aim of this paper is to present these efforts. Among others, a 3-D seismic survey completed in 1998 and a stratigraphic framework built from 149 vertical wells were used for reservoir characterization. Geostatistical techniques such as sequential Gaussian simulation with locally varying mean and cloud transform were also used. Results showed that these geostatistical methods accurately represented the architecture and properties of the reservoir and its fluid distribution. This paper showed that the application of numerous different techniques in the Hamasca area permitted reservoir complexity to be captured.

  9. PHYSIOTHERAPY FOR CLUMSY CHILDREN - AN EVALUATION STUDY

    NARCIS (Netherlands)

    SCHOEMAKER, MM; HIJLKEMA, MGJ; KALVERBOER, AF

    This study reports the findings of an effect-evaluation study of physiotherapy for clumsy children. 18 children were identified by school doctors as having poor motor co-ordination. They were followed for three months in order to exclude spontaneous improvement of motor problems; none spontaneously

  10. Groundwater quality assessment of the shallow aquifers west of the Nile Delta (Egypt) using multivariate statistical and geostatistical techniques

    Science.gov (United States)

    Masoud, Alaa A.

    2014-07-01

    Extensive urban, agricultural and industrial expansions on the western fringe of the Nile Delta of Egypt have exerted much load on the water needs and lead to groundwater quality deterioration. Documenting the spatial variation of the groundwater quality and their controlling factors is vital to ensure sustainable water management and safe use. A comprehensive dataset of 451 shallow groundwater samples were collected in 2011 and 2012. On-site field measurements of the total dissolved solids (TDS), electric conductivity (EC), pH, temperature, as well as lab-based ionic composition of the major and trace components were performed. Groundwater types were derived and the suitability for irrigation use was evaluated. Multivariate statistical techniques of factor analysis and K-means clustering were integrated with the geostatistical semi-variogram modeling for evaluating the spatial hydrochemical variations and the driving factors as well as for hydrochemical pattern recognition. Most hydrochemical parameters showed very wide ranges; TDS (201-24,400 mg/l), pH (6.72-8.65), Na+ (28.30-7774 mg/l), and Cl- (7-12,186 mg/l) suggesting complex hydrochemical processes of multiple sources. TDS violated the limit (1200 mg/l) of the Egyptian standards for drinking water quality in many localities. Extreme concentrations of Fe2+, Mn2+, Zn2+, Cu2+, Ni2+, are mostly related to their natural content in the water-bearing sediments and/or to contamination from industrial leakage. Very high nitrate concentrations exceeding the permissible limit (50 mg/l) were potentially maximized toward hydrologic discharge zones and related to wastewater leakage. Three main water types; NaCl (29%), Na2SO4 (26%), and NaHCO3 (20%), formed 75% of the groundwater dominated in the saline depressions, sloping sides of the coastal ridges of the depressions, and in the cultivated/newly reclaimed lands intensely covered by irrigation canals, respectively. Water suitability for irrigation use clarified that the

  11. Multivariate Analysis and Modeling of Sediment Pollution Using Neural Network Models and Geostatistics

    Science.gov (United States)

    Golay, Jean; Kanevski, Mikhaïl

    2013-04-01

    The present research deals with the exploration and modeling of a complex dataset of 200 measurement points of sediment pollution by heavy metals in Lake Geneva. The fundamental idea was to use multivariate Artificial Neural Networks (ANN) along with geostatistical models and tools in order to improve the accuracy and the interpretability of data modeling. The results obtained with ANN were compared to those of traditional geostatistical algorithms like ordinary (co)kriging and (co)kriging with an external drift. Exploratory data analysis highlighted a great variety of relationships (i.e. linear, non-linear, independence) between the 11 variables of the dataset (i.e. Cadmium, Mercury, Zinc, Copper, Titanium, Chromium, Vanadium and Nickel as well as the spatial coordinates of the measurement points and their depth). Then, exploratory spatial data analysis (i.e. anisotropic variography, local spatial correlations and moving window statistics) was carried out. It was shown that the different phenomena to be modeled were characterized by high spatial anisotropies, complex spatial correlation structures and heteroscedasticity. A feature selection procedure based on General Regression Neural Networks (GRNN) was also applied to create subsets of variables enabling to improve the predictions during the modeling phase. The basic modeling was conducted using a Multilayer Perceptron (MLP) which is a workhorse of ANN. MLP models are robust and highly flexible tools which can incorporate in a nonlinear manner different kind of high-dimensional information. In the present research, the input layer was made of either two (spatial coordinates) or three neurons (when depth as auxiliary information could possibly capture an underlying trend) and the output layer was composed of one (univariate MLP) to eight neurons corresponding to the heavy metals of the dataset (multivariate MLP). MLP models with three input neurons can be referred to as Artificial Neural Networks with EXternal

  12. Agricultura de precisão: mapeamento da produtividade em pomares cítricos usando geoestatística Precision agriculture: mapping yield in citrus groves using geostatistics

    Directory of Open Access Journals (Sweden)

    Paulo Roberto Silva Farias

    2003-08-01

    Full Text Available A variabilidade espacial de produtividade e tamanho de frutos foi avaliada em pomares de laranja irrigados e não irrigados, localizados no município de Luiz Antônio - SP, utilizando-se de geoestatística. Através dos mapas de krigagem, podem-se determinar as áreas de alta e baixa produtividade dos talhões. Verificou-se maior variabilidade para produtividade e tamanho de frutos nas quadras irrigadas e não irrigadas. Portanto, a geoestatística mostrou-se uma ferramenta extremamente útil para auxiliar em Programas de Agricultura de Precisão.The yield variability of sweet orange groves located in Luiz Antonio country, Sao Paulo State, Brazil, was evaluated using geostatistics. Through the kriging maps, areas with higher and lower yields in the groves were determinated. A great variability of yield and fruit size on irrigated and non-irrigated groves was verified. Thus, the geostatistic showed to be an extremely useful tool to enhance Precision Agriculture Programs.

  13. A Comparison of Traditional, Step-Path, and Geostatistical Techniques in the Stability Analysis of a Large Open Pit

    Science.gov (United States)

    Mayer, J. M.; Stead, D.

    2017-04-01

    With the increased drive towards deeper and more complex mine designs, geotechnical engineers are often forced to reconsider traditional deterministic design techniques in favour of probabilistic methods. These alternative techniques allow for the direct quantification of uncertainties within a risk and/or decision analysis framework. However, conventional probabilistic practices typically discretize geological materials into discrete, homogeneous domains, with attributes defined by spatially constant random variables, despite the fact that geological media display inherent heterogeneous spatial characteristics. This research directly simulates this phenomenon using a geostatistical approach, known as sequential Gaussian simulation. The method utilizes the variogram which imposes a degree of controlled spatial heterogeneity on the system. Simulations are constrained using data from the Ok Tedi mine site in Papua New Guinea and designed to randomly vary the geological strength index and uniaxial compressive strength using Monte Carlo techniques. Results suggest that conventional probabilistic techniques have a fundamental limitation compared to geostatistical approaches, as they fail to account for the spatial dependencies inherent to geotechnical datasets. This can result in erroneous model predictions, which are overly conservative when compared to the geostatistical results.

  14. Handbook for evaluation studies in virtual reality

    DEFF Research Database (Denmark)

    Livatino, Salvatore; Koeffel, Christina

    2006-01-01

    Virtual reality (VR) applications are spreading and attract industries since VR technologies are becoming more affordable, powerful and robust. VR applications inherently call for human-computer interaction, which in turn calls for system and usability evaluations, typically through measurement...... of human behavior including aspects of perception, action, and task-performance. The evaluation issue calls for multi- and interdisciplinary research activities, where technical expertise is combined with humanistic knowledge and methodology. Several experts in the field of VR as well as in the field...... of usability studies call for helpful guidelines in order to be able to evaluate VR applications. This paper gives an overview of this problem and introduces a guideline which is supposed to assist researchers in evaluating VR applications. In particular it aims at assisting those who are not experts...

  15. Factors affecting paddy soil arsenic concentration in Bangladesh: prediction and uncertainty of geostatistical risk mapping.

    Science.gov (United States)

    Ahmed, Zia U; Panaullah, Golam M; DeGloria, Stephen D; Duxbury, John M

    2011-12-15

    Knowledge of the spatial correlation of soil arsenic (As) concentrations with environmental variables is needed to assess the nature and extent of the risk of As contamination from irrigation water in Bangladesh. We analyzed 263 paired groundwater and paddy soil samples covering highland (HL) and medium highland-1 (MHL-1) land types for geostatistical mapping of soil As and delineation of As contaminated areas in Tala Upazilla, Satkhira district. We also collected 74 non-rice soil samples to assess the baseline concentration of soil As for this area. The mean soil As concentrations (mg/kg) for different land types under rice and non-rice crops were: rice-MHL-1 (21.2)>rice-HL (14.1)>non-rice-MHL-1 (11.9)>non-rice-HL (7.2). Multiple regression analyses showed that irrigation water As, Fe, land elevation and years of tubewell operation are the important factors affecting the concentrations of As in HL paddy soils. Only years of tubewell operation affected As concentration in the MHL-1 paddy soils. Quantitatively similar increases in soil As above the estimated baseline-As concentration were observed for rice soils on HL and MHL-1 after 6-8 years of groundwater irrigation, implying strong retention of As added in irrigation water in both land types. Application of single geostatistical methods with secondary variables such as regression kriging (RK) and ordinary co-kriging (OCK) gave little improvement in prediction of soil As over ordinary kriging (OK). Comparing single prediction methods, kriging within strata (KWS), the combination of RK for HL and OCK for MHL-1, gave more accurate soil As predictions and showed the lowest misclassification of declaring a location "contaminated" with respect to 14.8 mg As/kg, the highest value obtained for the baseline soil As concentration. Prediction of soil As buildup over time indicated that 75% or the soils cropped to rice would contain at least 30 mg/L As by the year 2020. Copyright © 2011 Elsevier B.V. All rights reserved.

  16. Information for decision making from imperfect national data: tracking major changes in health care use in Kenya using geostatistics

    Directory of Open Access Journals (Sweden)

    Hay Simon I

    2007-12-01

    Full Text Available Abstract Background Most Ministries of Health across Africa invest substantial resources in some form of health management information system (HMIS to coordinate the routine acquisition and compilation of monthly treatment and attendance records from health facilities nationwide. Despite the expense of these systems, poor data coverage means they are rarely, if ever, used to generate reliable evidence for decision makers. One critical weakness across Africa is the current lack of capacity to effectively monitor patterns of service use through time so that the impacts of changes in policy or service delivery can be evaluated. Here, we present a new approach that, for the first time, allows national changes in health service use during a time of major health policy change to be tracked reliably using imperfect data from a national HMIS. Methods Monthly attendance records were obtained from the Kenyan HMIS for 1 271 government-run and 402 faith-based outpatient facilities nationwide between 1996 and 2004. A space-time geostatistical model was used to compensate for the large proportion of missing records caused by non-reporting health facilities, allowing robust estimation of monthly and annual use of services by outpatients during this period. Results We were able to reconstruct robust time series of mean levels of outpatient utilisation of health facilities at the national level and for all six major provinces in Kenya. These plots revealed reliably for the first time a period of steady nationwide decline in the use of health facilities in Kenya between 1996 and 2002, followed by a dramatic increase from 2003. This pattern was consistent across different causes of attendance and was observed independently in each province. Conclusion The methodological approach presented can compensate for missing records in health information systems to provide robust estimates of national patterns of outpatient service use. This represents the first such use of

  17. A comparison of geostatistically based inverse techniques for use in performance assessment analysis at the Waste Isolation Pilot Plant Site: Results from Test Case No. 1

    International Nuclear Information System (INIS)

    Zimmerman, D.A.; Gallegos, D.P.

    1993-10-01

    The groundwater flow pathway in the Culebra Dolomite aquifer at the Waste Isolation Pilot Plant (WIPP) has been identified as a potentially important pathway for radionuclide migration to the accessible environment. Consequently, uncertainties in the models used to describe flow and transport in the Culebra need to be addressed. A ''Geostatistics Test Problem'' is being developed to evaluate a number of inverse techniques that may be used for flow calculations in the WIPP performance assessment (PA). The Test Problem is actually a series of test cases, each being developed as a highly complex synthetic data set; the intent is for the ensemble of these data sets to span the range of possible conceptual models of groundwater flow at the WIPP site. The Test Problem analysis approach is to use a comparison of the probabilistic groundwater travel time (GWTT) estimates produced by each technique as the basis for the evaluation. Participants are given observations of head and transmissivity (possibly including measurement error) or other information such as drawdowns from pumping wells, and are asked to develop stochastic models of groundwater flow for the synthetic system. Cumulative distribution functions (CDFs) of groundwater flow (computed via particle tracking) are constructed using the head and transmissivity data generated through the application of each technique; one semi-analytical method generates the CDFs of groundwater flow directly. This paper describes the results from Test Case No. 1

  18. Geostatistical methods for rock mass quality prediction using borehole and geophysical survey data

    Science.gov (United States)

    Chen, J.; Rubin, Y.; Sege, J. E.; Li, X.; Hehua, Z.

    2015-12-01

    For long, deep tunnels, the number of geotechnical borehole investigations during the preconstruction stage is generally limited. Yet tunnels are often constructed in geological structures with complex geometries, and in which the rock mass is fragmented from past structural deformations. Tunnel Geology Prediction (TGP) is a geophysical technique widely used during tunnel construction in China to ensure safety during construction and to prevent geological disasters. In this paper, geostatistical techniques were applied in order to integrate seismic velocity from TGP and borehole information into spatial predictions of RMR (Rock Mass Rating) in unexcavated areas. This approach is intended to apply conditional probability methods to transform seismic velocities to directly observed RMR values. The initial spatial distribution of RMR, inferred from the boreholes, was updated by including geophysical survey data in a co-kriging approach. The method applied to a real tunnel project shows significant improvements in rock mass quality predictions after including geophysical survey data, leading to better decision-making for construction safety design.

  19. Characterisation and geostatistical analysis of clay rocks in underground facilities using hyper-spectral images

    International Nuclear Information System (INIS)

    Becker, J.K.; Marschall, P.; Brunner, P.; Cholet, C.; Renard, P.; Buckley, S.; Kurz, T.

    2012-01-01

    Document available in extended abstract form only. Flow and transport processes in geological formations are controlled by the porosity and permeability which in turn are mainly controlled by the fabric and the mineralogical composition of the rock. For the assessment of transport processes in water-saturated Clay-stone formations, the relevant scales are ranging essentially from kilometers to nanometers. The spatial variability of the mineralogical composition is a key indicator for the separation of transport scales and for the derivation of the effective transport properties at a given scale. Various laboratory and in-situ techniques are available for characterizing the mineralogical composition of a rock on different scales. The imaging spectroscopy presented in this paper is a new site investigation method suitable for mapping the mineralogical composition of geological formations in 2D on a large range of scales. A combination of imaging spectrometry with other site characterization methods allows the inference of the spatial variability of the mineralogical composition in 3D over a wide range of scales with the help of advanced geostatistical methods. The method of image spectrometry utilizes the fact that the reflection of electromagnetic radiation from a surface is a function of the wavelength, the chemical-mineralogical surface properties, and physical parameters such as the grain size and surface roughness. In remote sensing applications using the sun as the light source, the reflectance is measured within the visible and infrared range, according to the atmospheric transmissibility. Many rock-forming minerals exhibit diagnostic absorption features within this range, which are caused by electronic and vibrational processes within the crystal lattice. The exact wavelength of an absorption feature is controlled by the type of ion, as well as the position of the ion within the lattice. Spectral signatures of minerals are described by a number of authors

  20. Spatiotemporal mapping of ground water pollution in a Greek lignite basin, using geostatistics

    Energy Technology Data Exchange (ETDEWEB)

    Modis, K. [National Technical Univ. of Athens, Athens (Greece)

    2010-07-01

    An issue of significant interest in the mining industry in Greece is the occurrence of chemical pollutants in ground water. Ammonium, nitrites and nitrates concentrations have been monitored through an extensive sampling network in the Ptolemais lignite opencast mining area in Greece. Due to intensive mining efforts in the area, the surface topology is continuously altered, affecting the life span of the water boreholes and resulting in messy spatiotemporal distribution of data. This paper discussed the spatiotemporal mapping of ground water pollution in the Ptolemais lignite basin, using geostatistics. More specifically, the spatiotemporal distribution of ground water contamination was examined by the application of the bayesian maximum entropy theory which allows merging spatial and temporal estimations in a single model. The paper provided a description of the site and discussed the materials and methods, including samples and statistics; variography; and spatiotemporal mapping. It was concluded that in the case of the Ptolemais mining area, results revealed an underlying average yearly variation pattern of pollutant concentrations. Inspection of the produced spatiotemporal maps demonstrated a continuous increase in the risk of ammonium contamination, while risk for the other two pollutants appeared in hot spots. 18 refs., 1 tab., 7 figs.

  1. Forward modeling of gravity data using geostatistically generated subsurface density variations

    Science.gov (United States)

    Phelps, Geoffrey

    2016-01-01

    Using geostatistical models of density variations in the subsurface, constrained by geologic data, forward models of gravity anomalies can be generated by discretizing the subsurface and calculating the cumulative effect of each cell (pixel). The results of such stochastically generated forward gravity anomalies can be compared with the observed gravity anomalies to find density models that match the observed data. These models have an advantage over forward gravity anomalies generated using polygonal bodies of homogeneous density because generating numerous realizations explores a larger region of the solution space. The stochastic modeling can be thought of as dividing the forward model into two components: that due to the shape of each geologic unit and that due to the heterogeneous distribution of density within each geologic unit. The modeling demonstrates that the internally heterogeneous distribution of density within each geologic unit can contribute significantly to the resulting calculated forward gravity anomaly. Furthermore, the stochastic models match observed statistical properties of geologic units, the solution space is more broadly explored by producing a suite of successful models, and the likelihood of a particular conceptual geologic model can be compared. The Vaca Fault near Travis Air Force Base, California, can be successfully modeled as a normal or strike-slip fault, with the normal fault model being slightly more probable. It can also be modeled as a reverse fault, although this structural geologic configuration is highly unlikely given the realizations we explored.

  2. Spatiotemporal mapping of ground water pollution in a Greek lignite basin, using geostatistics

    International Nuclear Information System (INIS)

    Modis, K.

    2010-01-01

    An issue of significant interest in the mining industry in Greece is the occurrence of chemical pollutants in ground water. Ammonium, nitrites and nitrates concentrations have been monitored through an extensive sampling network in the Ptolemais lignite opencast mining area in Greece. Due to intensive mining efforts in the area, the surface topology is continuously altered, affecting the life span of the water boreholes and resulting in messy spatiotemporal distribution of data. This paper discussed the spatiotemporal mapping of ground water pollution in the Ptolemais lignite basin, using geostatistics. More specifically, the spatiotemporal distribution of ground water contamination was examined by the application of the bayesian maximum entropy theory which allows merging spatial and temporal estimations in a single model. The paper provided a description of the site and discussed the materials and methods, including samples and statistics; variography; and spatiotemporal mapping. It was concluded that in the case of the Ptolemais mining area, results revealed an underlying average yearly variation pattern of pollutant concentrations. Inspection of the produced spatiotemporal maps demonstrated a continuous increase in the risk of ammonium contamination, while risk for the other two pollutants appeared in hot spots. 18 refs., 1 tab., 7 figs.

  3. [Geostatistical analysis on distribution dynamics of Myzus persicae (Sulzer) in flue-cured tobacco field].

    Science.gov (United States)

    Xia, Peng-liang; Liu, Ying-hong; Fan, Jun; Tan, Jun

    2015-02-01

    Abstract: Myzus persicae belonging to Aphididae, Hemiptera, is an important migratory pest in tobacco field. As nymph and adult, it sucks the juice, breeds the mildew stains disease, spreads tobacco virus diseases and causes huge losses to the yield and quality. The distribution pattern and dynamics of winged and wingless aphids in the field were investigated from the transplanting of tobacco to the harvesting stage of mid-place tobacco leaves in Enshi, Hubei. The semivariable function characteristics were analyzed by geostatistical method, and the field migration pattern were simulated. The results showed that the population dynamics of winged aphids in Enshi were of bimodal curve, with two peaks at 3 weeks after transplanting and 2 weeks after multi-topping of tobacco leaves, and there were five-step process such as random, aggregation, random, aggregation and random. The population dynamics of wingless peach aphids were of single-peak curve, getting its peak before multi-topping, and had random, aggregation, random three-step process. Human factors and the hosts had considerable effects on the population density. Spatial distribution simulation-interpolation-figure could clearly reflect the dynamics of tobacco aphids. Combined with the Pearson correlation analysis, we found that the population density was low and highly concentrated as winged type in the immigration period, which was the key period for the management of peach aphids.

  4. Determining site-specific background level with geostatistics for remediation of heavy metals in neighborhood soils

    Directory of Open Access Journals (Sweden)

    Tammy M. Milillo

    2017-03-01

    Full Text Available The choice of a relevant, uncontaminated site for the determination of site-specific background concentrations for pollutants is critical for planning remediation of a contaminated site. The guidelines used to arrive at concentration levels vary from state to state, complicating this process. The residential neighborhood of Hickory Woods in Buffalo, NY is an area where heavy metal concentrations and spatial distributions were measured to plan remediation. A novel geostatistics based decision making framework that relies on maps generated from indicator kriging (IK and indicator co-kriging (ICK of samples from the contaminated site itself is shown to be a viable alternative to the traditional method of choosing a reference site for remediation planning. GIS based IK and ICK, and map based analysis are performed on lead and arsenic surface and subsurface datasets to determine site-specific background concentration levels were determined to be 50 μg/g for lead and 10 μg/g for arsenic. With these results, a remediation plan was proposed which identified regions of interest and maps were created to effectively communicate the results to the environmental agencies, residents and other interested parties.

  5. Using geostatistical methods to estimate snow water equivalence distribution in a mountain watershed

    Science.gov (United States)

    Balk, B.; Elder, K.; Baron, Jill S.

    1998-01-01

    Knowledge of the spatial distribution of snow water equivalence (SWE) is necessary to adequately forecast the volume and timing of snowmelt runoff.  In April 1997, peak accumulation snow depth and density measurements were independently taken in the Loch Vale watershed (6.6 km2), Rocky Mountain National Park, Colorado.  Geostatistics and classical statistics were used to estimate SWE distribution across the watershed.  Snow depths were spatially distributed across the watershed through kriging interpolation methods which provide unbiased estimates that have minimum variances.  Snow densities were spatially modeled through regression analysis.  Combining the modeled depth and density with snow-covered area (SCA produced an estimate of the spatial distribution of SWE.  The kriged estimates of snow depth explained 37-68% of the observed variance in the measured depths.  Steep slopes, variably strong winds, and complex energy balance in the watershed contribute to a large degree of heterogeneity in snow depth.

  6. A geostatistical approach to large-scale disease mapping with temporal misalignment.

    Science.gov (United States)

    Hund, Lauren; Chen, Jarvis T; Krieger, Nancy; Coull, Brent A

    2012-09-01

    Temporal boundary misalignment occurs when area boundaries shift across time (e.g., census tract boundaries change at each census year), complicating the modeling of temporal trends across space. Large area-level datasets with temporal boundary misalignment are becoming increasingly common in practice. The few existing approaches for temporally misaligned data do not account for correlation in spatial random effects over time. To overcome issues associated with temporal misalignment, we construct a geostatistical model for aggregate count data by assuming that an underlying continuous risk surface induces spatial correlation between areas. We implement the model within the framework of a generalized linear mixed model using radial basis splines. Using this approach, boundary misalignment becomes a nonissue. Additionally, this disease-mapping framework facilitates fast, easy model fitting by using a penalized quasilikelihood approximation to maximum likelihood estimation. We anticipate that the method will also be useful for large disease-mapping datasets for which fully Bayesian approaches are infeasible. We apply our method to assess socioeconomic trends in breast cancer incidence in Los Angeles between the periods 1988-1992 and 1998-2002. © 2011, The International Biometric Society.

  7. Geostatistical analysis of tritium, groundwater age and other noble gas derived parameters in California.

    Science.gov (United States)

    Visser, A; Moran, J E; Hillegonds, Darren; Singleton, M J; Kulongoski, Justin T; Belitz, Kenneth; Esser, B K

    2016-03-15

    Key characteristics of California groundwater systems related to aquifer vulnerability, sustainability, recharge locations and mechanisms, and anthropogenic impact on recharge are revealed in a spatial geostatistical analysis of a unique data set of tritium, noble gases and other isotopic analyses unprecedented in size at nearly 4000 samples. The correlation length of key groundwater residence time parameters varies between tens of kilometers ((3)H; age) to the order of a hundred kilometers ((4)Heter; (14)C; (3)Hetrit). The correlation length of parameters related to climate, topography and atmospheric processes is on the order of several hundred kilometers (recharge temperature; δ(18)O). Young groundwater ages that highlight regional recharge areas are located in the eastern San Joaquin Valley, in the southern Santa Clara Valley Basin, in the upper LA basin and along unlined canals carrying Colorado River water, showing that much of the recent recharge in central and southern California is dominated by river recharge and managed aquifer recharge. Modern groundwater is found in wells with the top open intervals below 60 m depth in the southeastern San Joaquin Valley, Santa Clara Valley and Los Angeles basin, as the result of intensive pumping and/or managed aquifer recharge operations. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Inverse modeling of hydraulic tests in fractured crystalline rock based on a transition probability geostatistical approach

    Science.gov (United States)

    Blessent, Daniela; Therrien, René; Lemieux, Jean-Michel

    2011-12-01

    This paper presents numerical simulations of a series of hydraulic interference tests conducted in crystalline bedrock at Olkiluoto (Finland), a potential site for the disposal of the Finnish high-level nuclear waste. The tests are in a block of crystalline bedrock of about 0.03 km3 that contains low-transmissivity fractures. Fracture density, orientation, and fracture transmissivity are estimated from Posiva Flow Log (PFL) measurements in boreholes drilled in the rock block. On the basis of those data, a geostatistical approach relying on a transitional probability and Markov chain models is used to define a conceptual model based on stochastic fractured rock facies. Four facies are defined, from sparsely fractured bedrock to highly fractured bedrock. Using this conceptual model, three-dimensional groundwater flow is then simulated to reproduce interference pumping tests in either open or packed-off boreholes. Hydraulic conductivities of the fracture facies are estimated through automatic calibration using either hydraulic heads or both hydraulic heads and PFL flow rates as targets for calibration. The latter option produces a narrower confidence interval for the calibrated hydraulic conductivities, therefore reducing the associated uncertainty and demonstrating the usefulness of the measured PFL flow rates. Furthermore, the stochastic facies conceptual model is a suitable alternative to discrete fracture network models to simulate fluid flow in fractured geological media.

  9. Geostatistical analysis for soil moisture content under the no tillage cropping system Análise geoestatística do teor de água do solo sob sistema de cultivo em plantio direto

    Directory of Open Access Journals (Sweden)

    Célia Regina Grego

    2006-08-01

    Full Text Available Experiments in agriculture usually consider the topsoil properties to be uniform in space and, for this reason, often make inadequate use of the results. The objective of this study was to assess the variability for soil moisture content using geostatistical techniques. The experiment was carried out on a Rhodic Ferralsol (typic Haplorthox in Campinas, SP, Brazil, in an area of 3.42 ha cultivated under the no tillage system, and the sampling was made in a grid of 102 points spaced 10 m x 20 m. Access tubes were inserted down to one meter at each evaluation point in order to measure soil moisture contents (cm³ cm-3 at depths of 30, 60 and 90 cm with a neutron moisture gauge. Samplings were made between the months of August and September of 2003 and in January 2004. The soil moisture content for each sampling date was analyzed using classical statistics in order to appropriately describe the central tendency and dispersion on the data and then using geostatistics to describe the spatial variability. The comparison between the spatial variability for different samplings was made examining scaled semivariograms. Water content was mapped using interpolated values with punctual kriging. The semivariograms showed that, at the 60 cm depth, soil water content had moderate spatial dependence with ranges between 90 and 110 m. However, no spatial dependence was found for 30 and 90 cm depths in 2003. Sampling density was insufficient for an adequate characterization of the spatial variability of soil moisture contents at the 30 and 90 cm depths.Experimentos em agricultura geralmente consideram as propriedades do solo como sendo uniformes no espaço e, por esta razão, os resultados são freqüentemente mal interpretados. O objetivo deste estudo foi avaliar a variabilidade do teor de água do solo usando técnicas de geoestatística. O experimento foi desenvolvido em um Latossolo Vermelho eutroférrico, Campinas, SP, Brasil, numa área de 3,42 ha sob plantio

  10. Geostatistical characterization of soil pollution at industrial sites Case of polycyclic aromatic hydrocarbons at former coking plants; Caracterisation geostatistique de pollutions industrielles de sols cas des hydrocarbures aromatiques polycycliques sur d'anciens sites de cokeries

    Energy Technology Data Exchange (ETDEWEB)

    Jeannee, N.

    2001-05-15

    Estimating polycyclic aromatic hydrocarbons concentrations in soil at former industrial sites poses several practical problems on account of the properties of the contaminants and the history of site: 1)collection and preparation of samples from highly heterogeneous material, 2) high short scale variability, particularly in presence of backfill, 3) highly contrasted grades making the vario-gram inference complicated. The sampling strategy generally adopted for contaminated sites is based on the historical information. Systematic sampling recommended for geostatistical estimation is often considered to be excessive and unnecessary. Two former coking plants are used as test cases for comparing several geostatistical methods for estimating (i) in situ concentrations and (ii) the probability that they are above a pollution threshold. Several practical and methodological questions are considered: 1) the properties of various estimators of the experimental vario-gram and the validity of the results; 2) the use of soft data, such as historical information, organoleptic observations and semi-quantitative methods, with a view to improve the precision of the estimates; 3) the comparison of standard sampling strategies, taking into account vertical repartition of grades and the history of the site. Multiple analyses of the same sample give an approximation of the sampling error. Short scale sampling shows the difficulty of selecting soils in the absence of a spatial structure. Sensitivity studies are carried out to assess how densely sampled soft data can improve estimates. By using mainly existing models, this work aims at giving practical recommendations for the characterization of soil pollution. (author)

  11. Improving a spatial rainfall product using multiple-point geostatistical simulations and its effect on a national hydrological model.

    Science.gov (United States)

    Oriani, F.; Stisen, S.

    2016-12-01

    Rainfall amount is one of the most sensitive inputs to distributed hydrological models. Its spatial representation is of primary importance to correctly study the uncertainty of basin recharge and its propagation to the surface and underground circulation. We consider here the 10-km-grid rainfall product provided by the Danish Meteorological Institute as input to the National Water Resources Model of Denmark. Due to a drastic reduction in the rain gauge network in recent years (from approximately 500 stations in the period 1996-2006, to 250 in the period 2007-2014), the grid rainfall product, based on the interpolation of these data, is much less reliable. Consequently, the related hydrological model shows a significantly lower prediction power. To give a better estimation of spatial rainfall at the grid points far from ground measurements, we use the direct sampling technique (DS) [1], belonging to the family of multiple-point geostatistics. DS, already applied to rainfall and spatial variable estimation [2, 3], simulates a grid value by sampling a training data set where a similar data neighborhood occurs. In this way, complex statistical relations are preserved by generating similar spatial patterns to the ones found in the training data set. Using the reliable grid product from the period 1996-2006 as training data set, we first test the technique by simulating part of this data set, then we apply the technique to the grid product of the period 2007-2014, and subsequently analyzing the uncertainty propagation to the hydrological model. We show that DS can improve the reliability of the rainfall product by generating more realistic rainfall patterns, with a significant repercussion on the hydrological model. The reduction of rain gauge networks is a global phenomenon which has huge implications for hydrological model performance and the uncertainty assessment of water resources. Therefore, the presented methodology can potentially be used in many regions where

  12. Fine-Resolution Precipitation Mapping in a Mountainous Watershed: Geostatistical Downscaling of TRMM Products Based on Environmental Variables

    Directory of Open Access Journals (Sweden)

    Yueyuan Zhang

    2018-01-01

    Full Text Available Accurate precipitation data at a high spatial resolution are essential for hydrological, meteorological, and ecological research at regional scales. This study presented a geostatistical downscaling-calibration procedure to derive the high spatial resolution maps of precipitation over a mountainous watershed affected by a monsoon climate. Based on the relationships between precipitation and other environmental variables, such as the Normalized Difference Vegetation Index (NDVI and digital elevation model (DEM, a regression model with a residual correction method was applied to downscale the Tropical Rainfall Measuring Mission (TRMM 3B43 product from coarse resolution (25 km to fine resolution (1 km. Two methods, geographical difference analysis (GDA and geographical ratio analysis (GRA, were used to calibrate the downscaled TRMM precipitation data. Monthly 1 km precipitation data were obtained by disaggregating 1 km annual downscaled and calibrated precipitation data using monthly fractions derived from original TRMM data. The downscaled precipitation datasets were validated against ground observations measured by rain gauges. According to the comparison of different regression models and residual interpolation methods, a geographically-weighted regression kriging (GWRK method was accepted to conduct the downscaling of TRMM data. The downscaled TRMM precipitation data obtained using GWRK described the spatial patterns of precipitation reasonably well at a spatial resolution of 1 km with more detailed information when compared with the original TRMM precipitation. The results of validation indicated that the GRA method provided results with higher accuracy than that of the GDA method. The final annual and monthly downscaled precipitation not only had significant improvement in spatial resolution, but also agreed well with data from the validation rain gauge stations (i.e., R2 = 0.72, RMSE = 161.0 mm, MAE = 127.5 mm, and Bias = 0.050 for annual

  13. Risk mapping of clonorchiasis in the People's Republic of China: A systematic review and Bayesian geostatistical analysis.

    Directory of Open Access Journals (Sweden)

    Ying-Si Lai

    2017-03-01

    Full Text Available Clonorchiasis, one of the most important food-borne trematodiases, affects more than 12 million people in the People's Republic of China (P.R. China. Spatially explicit risk estimates of Clonorchis sinensis infection are needed in order to target control interventions.Georeferenced survey data pertaining to infection prevalence of C. sinensis in P.R. China from 2000 onwards were obtained via a systematic review in PubMed, ISI Web of Science, Chinese National Knowledge Internet, and Wanfang Data from January 1, 2000 until January 10, 2016, with no restriction of language or study design. Additional disease data were provided by the National Institute of Parasitic Diseases, Chinese Center for Diseases Control and Prevention in Shanghai. Environmental and socioeconomic proxies were extracted from remote-sensing and other data sources. Bayesian variable selection was carried out to identify the most important predictors of C. sinensis risk. Geostatistical models were applied to quantify the association between infection risk and the predictors of the disease, and to predict the risk of infection across P.R. China at high spatial resolution (over a grid with grid cell size of 5×5 km.We obtained clonorchiasis survey data at 633 unique locations in P.R. China. We observed that the risk of C. sinensis infection increased over time, particularly from 2005 onwards. We estimate that around 14.8 million (95% Bayesian credible interval 13.8-15.8 million people in P.R. China were infected with C. sinensis in 2010. Highly endemic areas (≥ 20% were concentrated in southern and northeastern parts of the country. The provinces with the highest risk of infection and the largest number of infected people were Guangdong, Guangxi, and Heilongjiang.Our results provide spatially relevant information for guiding clonorchiasis control interventions in P.R. China. The trend toward higher risk of C. sinensis infection in the recent past urges the Chinese government to

  14. A connectionist-geostatistical approach for classification of deformation types in ice surfaces

    Science.gov (United States)

    Goetz-Weiss, L. R.; Herzfeld, U. C.; Hale, R. G.; Hunke, E. C.; Bobeck, J.

    2014-12-01

    Deformation is a class of highly non-linear geophysical processes from which one can infer other geophysical variables in a dynamical system. For example, in an ice-dynamic model, deformation is related to velocity, basal sliding, surface elevation changes, and the stress field at the surface as well as internal to a glacier. While many of these variables cannot be observed, deformation state can be an observable variable, because deformation in glaciers (once a viscosity threshold is exceeded) manifests itself in crevasses.Given the amount of information that can be inferred from observing surface deformation, an automated method for classifying surface imagery becomes increasingly desirable. In this paper a Neural Network is used to recognize classes of crevasse types over the Bering Bagley Glacier System (BBGS) during a surge (2011-2013-?). A surge is a spatially and temporally highly variable and rapid acceleration of the glacier. Therefore, many different crevasse types occur in a short time frame and in close proximity, and these crevasse fields hold information on the geophysical processes of the surge.The connectionist-geostatistical approach uses directional experimental (discrete) variograms to parameterize images into a form that the Neural Network can recognize. Recognizing that each surge wave results in different crevasse types and that environmental conditions affect the appearance in imagery, we have developed a semi-automated pre-training software to adapt the Neural Net to chaining conditions.The method is applied to airborne and satellite imagery to classify surge crevasses from the BBGS surge. This method works well for classifying spatially repetitive images such as the crevasses over Bering Glacier. We expand the network for less repetitive images in order to analyze imagery collected over the Arctic sea ice, to assess the percentage of deformed ice for model calibration.

  15. UNCERT: geostatistics, uncertainty analysis and visualization software applied to groundwater flow and contaminant transport modeling

    International Nuclear Information System (INIS)

    Wingle, W.L.; Poeter, E.P.; McKenna, S.A.

    1999-01-01

    UNCERT is a 2D and 3D geostatistics, uncertainty analysis and visualization software package applied to ground water flow and contaminant transport modeling. It is a collection of modules that provides tools for linear regression, univariate statistics, semivariogram analysis, inverse-distance gridding, trend-surface analysis, simple and ordinary kriging and discrete conditional indicator simulation. Graphical user interfaces for MODFLOW and MT3D, ground water flow and contaminant transport models, are provided for streamlined data input and result analysis. Visualization tools are included for displaying data input and output. These include, but are not limited to, 2D and 3D scatter plots, histograms, box and whisker plots, 2D contour maps, surface renderings of 2D gridded data and 3D views of gridded data. By design, UNCERT's graphical user interface and visualization tools facilitate model design and analysis. There are few built in restrictions on data set sizes and each module (with two exceptions) can be run in either graphical or batch mode. UNCERT is in the public domain and is available from the World Wide Web with complete on-line and printable (PDF) documentation. UNCERT is written in ANSI-C with a small amount of FORTRAN77, for UNIX workstations running X-Windows and Motif (or Lesstif). This article discusses the features of each module and demonstrates how they can be used individually and in combination. The tools are applicable to a wide range of fields and are currently used by researchers in the ground water, mining, mathematics, chemistry and geophysics, to name a few disciplines. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  16. Distribuição espacial de Huanglongbing (Greening em citros utilizando a geoestatística Spatial distribuition of Huanglongbing (Greening on citrus using geostatistic

    Directory of Open Access Journals (Sweden)

    Renata Moreira Leal

    2010-09-01

    Full Text Available Os objetivos do trabalho foram avaliar a distribuição espacial e a expansão da Huanglongbing (greening em talhões de citros de uma propriedade agrícola localizada no município de Araraquara-SP, utilizando a geoestatística. Para determinar o número de plantas com greening, foram realizadas inspeções periódicas em intervalos de três meses, no período de março de 2005 a julho de 2007, contando-se, em cada talhão, o número de plantas com os sintomas característicos da doença. Realizou-se a análise descritiva dos dados e, para verificar a distribuição espacial do greening, utilizou-se a geoestatística através do ajuste de semivariogramas e da interpolação dos dados por krigagem. A dependência espacial de plantas com greening apresentou raio de agregação de 300 a 560 m, indicando distribuição agregada da doença. Por meio dos mapas de krigagem, observou-se que o foco inicial de plantas doentes ocorreu nos limites da fazenda, com expansão do greening por toda a área. O intervalo de inspeção de três meses não foi adequado para a redução do greening na fazenda.The aim of this study was to use geostatistics to verify the spatial distribution of Huanglongbing (greening in oranges orchards on agricultural property located in the city of Araraquara, São Paulo. To determine the number of plants with greening, periodic inspections the three months were made from March 2005 until July 2007, counting the number of plants in each stand with the characteristic symptoms of the disease. A descriptive analysis of the data was undertaken, and geostatistics were used to verify the spatial distribution of greening through the adjustment of semivariograms and interpolation of data by kriging. The spatial dependence of plants with greening formed a beam of aggregation of 300 to 560 m, indicated an aggregated distribution of disease. Diagrams of kriging showed that initial focus of plants with greening started at the border in the

  17. Spatial assessment of soil organic carbon and physicochemical properties in a horticultural orchard at arid zone of India using geostatistical approaches.

    Science.gov (United States)

    Singh, Akath; Santra, Priyabrata; Kumar, Mahesh; Panwar, Navraten; Meghwal, P R

    2016-09-01

    Soil organic carbon (SOC) is a major indicator of long-term sustenance of agricultural production system. Apart from sustaining productivity, SOC plays a crucial role in context of climate change. Keeping in mind these potentials, spatial variation of SOC contents of a fruit orchard comprising several arid fruit plantations located at arid region of India is assessed in this study through geostatistical approaches. For this purpose, surface and subsurface soil samples from 175 locations from a fruit orchard spreading over 14.33 ha area were collected along with geographical coordinates. SOC content and soil physicochemical properties of collected soil samples were determined followed by geostatistical analysis for mapping purposes. Average SOC stock density of the orchard was 14.48 Mg ha(-1) for 0- to 30-cm soil layer ranging from 9.01 Mg ha(-1) in Carissa carandas to 19.52 Mg ha(-1) in Prosopis cineraria block. Range of spatial variation of SOC content was found about 100 m, while two other soil physicochemical properties, e.g., pH and electrical conductivity (EC) also showed similar spatial trend. This indicated that minimum sampling distance for future SOC mapping programme may be kept lower than 100 m for better accuracy. Ordinary kriging technique satisfactorily predicted SOC contents (in percent) at unsampled locations with root-mean-squared residual (RMSR) of 0.35-0.37. Co-kriging approach was found slightly superior (RMSR = 0.26-0.28) than ordinary kriging for spatial prediction of SOC contents because of significant correlations of SOC contents with pH and EC. Uncertainty of SOC estimation was also presented in terms of 90 % confidence interval. Spatial estimates of SOC stock through ordinary kriging or co-kriging approach were also found with low uncertainty of estimation than non-spatial estimates, e.g., arithmetic averaging approach. Among different fruit block plantations of the orchard, the block with Prosopis cineraria ('khejri') has

  18. Evaluation of roentgenologic study of the stomach

    International Nuclear Information System (INIS)

    Suh, Jung Ho; Choi, Byung So

    1972-01-01

    In order to achieve more correct diagnosis of gastric lesion, further progress in the technique of diagnosis is much desired. And so, in pursuing the more ideal study, about 7,500 cases of U. G. I. studies taken in Severance Hospital in the past 29 months from May 1969 to September 1971, have been reviewed to evaluate how the following factors will affect the demonstrability of gastric lesion in upper G. I. series. (1) Introduction of air into the stomach by nasogastric tube. (2) Kinds and concentration of barium. (3) Demonstrability according to the position of the patient. (4) Use of antispasmodics. The results may be briefly summarized as follows: 1. The intubation of nasogastric tube gives discomfort temporarily to the patient: however, it has an advantage that the amount of air required for ideal insufflation of the stomach can be controlled under the fluoroscopy. 2. About concentration and type of barium. a) Mikabarium in 90% seems to give the best result in filling study, mucosal relief study and double contrast study. b) Mikabarium in higher concentration adheres to the mucosa better, thus resulting in good double contrast: however, it tends to coagulate each other in the high concentration. c) Micropaque powder of 110% solution produces good double contrast, but it has the disadvantage of making air bubbles. d) When water is given prior to barium ingestion, the anterior wall of stomach is better demonstrated with mucosal relief study. e) To get better result in contrast study, the selection of barium is important as well as rapid and proper positioning of the patient and abdominal respiratory movement. 3. Demonstrability of the stomach lesion according to the position. a) The small lesion either in pylorus or in antrum can be best demonstrated by compression technique of double contrast method in supine position. b) The mucosal relief study in prone by adequate air insufflation was proper to demonstrate the lesion of anterior wall. c) In the lesion of the

  19. Evaluation of roentgenologic study of the stomach

    Energy Technology Data Exchange (ETDEWEB)

    Suh, Jung Ho; Choi, Byung So [Yonsei University College of Medicine, Seoul (Korea, Republic of)

    1972-09-15

    In order to achieve more correct diagnosis of gastric lesion, further progress in the technique of diagnosis is much desired. And so, in pursuing the more ideal study, about 7,500 cases of U. G. I. studies taken in Severance Hospital in the past 29 months from May 1969 to September 1971, have been reviewed to evaluate how the following factors will affect the demonstrability of gastric lesion in upper G. I. series. (1) Introduction of air into the stomach by nasogastric tube. (2) Kinds and concentration of barium. (3) Demonstrability according to the position of the patient. (4) Use of antispasmodics. The results may be briefly summarized as follows: 1. The intubation of nasogastric tube gives discomfort temporarily to the patient: however, it has an advantage that the amount of air required for ideal insufflation of the stomach can be controlled under the fluoroscopy. 2. About concentration and type of barium. a) Mikabarium in 90% seems to give the best result in filling study, mucosal relief study and double contrast study. b) Mikabarium in higher concentration adheres to the mucosa better, thus resulting in good double contrast: however, it tends to coagulate each other in the high concentration. c) Micropaque powder of 110% solution produces good double contrast, but it has the disadvantage of making air bubbles. d) When water is given prior to barium ingestion, the anterior wall of stomach is better demonstrated with mucosal relief study. e) To get better result in contrast study, the selection of barium is important as well as rapid and proper positioning of the patient and abdominal respiratory movement. 3. Demonstrability of the stomach lesion according to the position. a) The small lesion either in pylorus or in antrum can be best demonstrated by compression technique of double contrast method in supine position. b) The mucosal relief study in prone by adequate air insufflation was proper to demonstrate the lesion of anterior wall. c) In the lesion of the

  20. Ground motion input in seismic evaluation studies

    International Nuclear Information System (INIS)

    Sewell, R.T.; Wu, S.C.

    1996-07-01

    This report documents research pertaining to conservatism and variability in seismic risk estimates. Specifically, it examines whether or not artificial motions produce unrealistic evaluation demands, i.e., demands significantly inconsistent with those expected from real earthquake motions. To study these issues, two types of artificial motions are considered: (a) motions with smooth response spectra, and (b) motions with realistic variations in spectral amplitude across vibration frequency. For both types of artificial motion, time histories are generated to match target spectral shapes. For comparison, empirical motions representative of those that might result from strong earthquakes in the Eastern U.S. are also considered. The study findings suggest that artificial motions resulting from typical simulation approaches (aimed at matching a given target spectrum) are generally adequate and appropriate in representing the peak-response demands that may be induced in linear structures and equipment responding to real earthquake motions. Also, given similar input Fourier energies at high-frequencies, levels of input Fourier energy at low frequencies observed for artificial motions are substantially similar to those levels noted in real earthquake motions. In addition, the study reveals specific problems resulting from the application of Western U.S. type motions for seismic evaluation of Eastern U.S. nuclear power plants

  1. Expermental Studies of quantitative evaluation using HPLC

    Directory of Open Access Journals (Sweden)

    Ki Rok Kwon

    2005-06-01

    Full Text Available Methods : This study was conducted to carry out quantitative evaluation using HPLC Content analysis was done using HPLC Results : According to HPLC analysis, each BVA-1 contained approximately 0.36㎍ melittin, and BVA-2 contained approximately 0.54㎍ melittin. But the volume of coating was so minute, slight difference exists between each needle. Conclusion : Above results indicate that the bee venom acupuncture can complement shortcomings of syringe usage as a part of Oriental medicine treatment, but extensive researches should be done for further verification.

  2. Analysis of vadose zone tritium transport from an underground storage tank release using numerical modeling and geostatistics

    Energy Technology Data Exchange (ETDEWEB)

    Lee, K.H.

    1997-09-01

    Numerical and geostatistical analyses show that the artificial smoothing effect of kriging removes high permeability flow paths from hydrogeologic data sets, reducing simulated contaminant transport rates in heterogeneous vadose zone systems. therefore, kriging alone is not recommended for estimating the spatial distribution of soil hydraulic properties for contaminant transport analysis at vadose zone sites. Vadose zone transport if modeled more effectively by combining kriging with stochastic simulation to better represent the high degree of spatial variability usually found in the hydraulic properties of field soils. However, kriging is a viable technique for estimating the initial mass distribution of contaminants in the subsurface.

  3. Evaluation of craniofacial proportions: A pilot study.

    Science.gov (United States)

    Sadeghian, Saied; Motamedi, Ali Mohammad Kalantar; Haerian, Alireza; Rafiei, Elahe

    2015-01-01

    Regarding the need for determining the cephalometric norms for each population and the advantages of proportional analyses, we evaluated the variables of McNamara and Schwartz analyses and their relation in a pilot study on 6-17 years old Iranian students and provided formulas, which show these relations. In this descriptive-analytical study, a tatal of cephalometric radiographs from the archive documents of Orthodontic Department of Isfahan Dental School was selected and traced. The variables of McNamara and Schwartz analyses were investigated. The data were analyzed by t-test and linear regression and Spearman correlation coefficient tests using SPSS 12 software, and the significance was set at 0.05. Then, a formula was suggested for predicting the relation between the jaws, cranium and face. The variables measured in this study were significantly different between the genders (P < 0.05), except for Co-Gn (P = 0.055), and they were higher in boys. All variables significantly increased (P < 0.05) with age from 6 to 17 years. The formulas presented in this study can be used for calculating the amount of PNS-APmax, Go-APmax and the Co-Gn, anterior nasal spine-menton in the Iranian population. Within the limitation of this study, the formula presented in this study might be considered to predict the relation between jaw dimensions and cranial base and facial dimensions in the Iranian population.

  4. Improving Classification of Airborne Laser Scanning Echoes in the Forest-Tundra Ecotone Using Geostatistical and Statistical Measures

    Directory of Open Access Journals (Sweden)

    Nadja Stumberg

    2014-05-01

    Full Text Available The vegetation in the forest-tundra ecotone zone is expected to be highly affected by climate change and requires effective monitoring techniques. Airborne laser scanning (ALS has been proposed as a tool for the detection of small pioneer trees for such vast areas using laser height and intensity data. The main objective of the present study was to assess a possible improvement in the performance of classifying tree and nontree laser echoes from high-density ALS data. The data were collected along a 1000 km long transect stretching from southern to northern Norway. Different geostatistical and statistical measures derived from laser height and intensity values were used to extent and potentially improve more simple models ignoring the spatial context. Generalised linear models (GLM and support vector machines (SVM were employed as classification methods. Total accuracies and Cohen’s kappa coefficients were calculated and compared to those of simpler models from a previous study. For both classification methods, all models revealed total accuracies similar to the results of the simpler models. Concerning classification performance, however, the comparison of the kappa coefficients indicated a significant improvement for some models both using GLM and SVM, with classification accuracies >94%.

  5. Identification of the Hydrogeochemical Processes in Groundwater Using Classic Integrated Geochemical Methods and Geostatistical Techniques, in Amol-Babol Plain, Iran

    Science.gov (United States)

    Sheikhy Narany, Tahoora; Ramli, Mohammad Firuz; Aris, Ahmad Zaharin; Sulaiman, Wan Nor Azmin; Juahir, Hafizan; Fakharian, Kazem

    2014-01-01

    Hydrogeochemical investigations had been carried out at the Amol-Babol Plain in the north of Iran. Geochemical processes and factors controlling the groundwater chemistry are identified based on the combination of classic geochemical methods with geographic information system (GIS) and geostatistical techniques. The results of the ionic ratios and Gibbs plots show that water rock interaction mechanisms, followed by cation exchange, and dissolution of carbonate and silicate minerals have influenced the groundwater chemistry in the study area. The hydrogeochemical characteristics of groundwater show a shift from low mineralized Ca-HCO3, Ca-Na-HCO3, and Ca-Cl water types to high mineralized Na-Cl water type. Three classes, namely, C1, C2, and C3, have been classified using cluster analysis. The spatial distribution maps of Na+/Cl−, Mg2+/Ca2+, and Cl−/HCO3 − ratios and electrical conductivity values indicate that the carbonate and weathering of silicate minerals played a significant role in the groundwater chemistry on the southern and western sides of the plain. However, salinization process had increased due to the influence of the evaporation-precipitation process towards the north-eastern side of the study area. PMID:24523640

  6. Lattice Boltzmann Simulations of Fluid Flow in Continental Carbonate Reservoir Rocks and in Upscaled Rock Models Generated with Multiple-Point Geostatistics

    Directory of Open Access Journals (Sweden)

    J. Soete

    2017-01-01

    Full Text Available Microcomputed tomography (μCT and Lattice Boltzmann Method (LBM simulations were applied to continental carbonates to quantify fluid flow. Fluid flow characteristics in these complex carbonates with multiscale pore networks are unique and the applied method allows studying their heterogeneity and anisotropy. 3D pore network models were introduced to single-phase flow simulations in Palabos, a software tool for particle-based modelling of classic computational fluid dynamics. In addition, permeability simulations were also performed on rock models generated with multiple-point geostatistics (MPS. This allowed assessing the applicability of MPS in upscaling high-resolution porosity patterns into large rock models that exceed the volume limitations of the μCT. Porosity and tortuosity control fluid flow in these porous media. Micro- and mesopores influence flow properties at larger scales in continental carbonates. Upscaling with MPS is therefore necessary to overcome volume-resolution problems of CT scanning equipment. The presented LBM-MPS workflow is applicable to other lithologies, comprising different pore types, shapes, and pore networks altogether. The lack of straightforward porosity-permeability relationships in complex carbonates highlights the necessity for a 3D approach. 3D fluid flow studies provide the best understanding of flow through porous media, which is of crucial importance in reservoir modelling.

  7. Identification of the hydrogeochemical processes in groundwater using classic integrated geochemical methods and geostatistical techniques, in Amol-Babol Plain, Iran.

    Science.gov (United States)

    Sheikhy Narany, Tahoora; Ramli, Mohammad Firuz; Aris, Ahmad Zaharin; Sulaiman, Wan Nor Azmin; Juahir, Hafizan; Fakharian, Kazem

    2014-01-01

    Hydrogeochemical investigations had been carried out at the Amol-Babol Plain in the north of Iran. Geochemical processes and factors controlling the groundwater chemistry are identified based on the combination of classic geochemical methods with geographic information system (GIS) and geostatistical techniques. The results of the ionic ratios and Gibbs plots show that water rock interaction mechanisms, followed by cation exchange, and dissolution of carbonate and silicate minerals have influenced the groundwater chemistry in the study area. The hydrogeochemical characteristics of groundwater show a shift from low mineralized Ca-HCO3, Ca-Na-HCO3, and Ca-Cl water types to high mineralized Na-Cl water type. Three classes, namely, C1, C2, and C3, have been classified using cluster analysis. The spatial distribution maps of Na(+)/Cl(-), Mg(2+)/Ca(2+), and Cl(-)/HCO3 (-) ratios and electrical conductivity values indicate that the carbonate and weathering of silicate minerals played a significant role in the groundwater chemistry on the southern and western sides of the plain. However, salinization process had increased due to the influence of the evaporation-precipitation process towards the north-eastern side of the study area.

  8. Geostatistical Modelling of the Travertine Formation Associated with the Alicun de las Torres Thermal System by Using Electrical Tomography and Porosity Data

    International Nuclear Information System (INIS)

    Prado Perez, A. J.; Aracil, E.; Perez del Villar, L.

    2010-01-01

    In the framework of a Singular Strategic Project entitled: Advanced Technologies of Carbon, Capture and Storage (CCS)1', supported by the MICINN (Spain) and the FEDER founds (EU), specifically in the Carbon Storage Task, a comprehensive study on the CO 2 leakage as DIG (Dissolved Inorganic Carbon) in the Alicun de Las Torres (Prov. of Granada) natural analogue thermal system was envisaged. This analogous system is characterised by the presence of a very important travertine formation, which can be considered as a permanent and stable sink for CO 2 . Consequently, the estimation of the travertine mass has been a main objective of this investigation. For that, data from two complementary electrical tomography campaigns, previously treated by a powerful geostatistical tool, have been used, as well as the porosity average value of this travertine and the calcite density. Besides this, the statistical methodology applied has also allowed the establishment of a 3-D model of the travertine formation, displaying the geological contact between this formation and the underlying materials, as well as the contacts among the three units forming the travertine formation. (Author) 23 refs.

  9. Avisalmvac: evaluation studies of stability and toxicity

    Directory of Open Access Journals (Sweden)

    Daniela Botus,

    2008-12-01

    Full Text Available In Pasteur Institute laboratories there was developed AVISALMVAC, a vaccine against avian Salmonella, a biological product that contains S. enteritidis and S. typhimurium bacterin, with oil adjuvant. This paper presents the results of the studies regarding the stability and toxicity evaluation of this vaccine stored under conditions recommended by the manufacturer (2-80C at the end of the period of validity. The vaccine stability was assessed by serological and histopathological analysis of samples from SPF chickens vaccinated with the product at the end of the period of validity. The study of Avisalmvac toxicity was carried out by inoculation of the product or its components on Vero cell monolayer, and the effects were microscopically recorded or by MTT test, applied at 6 days post-inoculation. Antibody titers recorded at 2 and 3 weeks post vaccination demonstrated the vaccine ability (used after an year since manufacture to induce synthesis of specific antibodies and therefore, the product stability was proven. Histopathological examinations carried out on samples taken at 18 days post vaccinationfrom the vaccination site (skeletal muscle and skin and spleen, did not show any lesions associated to vaccination with Avisalmvac. The cytotoxicity analysis made by inoculating the vaccine or its components on Vero cell monolayer and the microscopic examination did not record visible cytopathic effects for any vaccine dilutions or vaccine components. The cell metabolism evaluation by MTT assay made at 6 days after vaccine/vaccine components inoculation on Vero monolayer, shown the ability of the vaccine and oil adjuvant to stimulate cell metabolism, and a certain degree of toxicity / inhibition of dehydrogenase metabolism associated to one of emulsifier but at dilutions higher than those used in the vaccine formula.

  10. Investigating Heuristic Evaluation: A Case Study.

    Science.gov (United States)

    Goldman, Kate Haley; Bendoly, Laura

    When museum professionals speak of evaluating a web site, they primarily mean formative evaluation, and by that they primarily mean testing the usability of the site. In the for-profit world, usability testing is a multi-million dollar industry, while non-profits often rely on far too few dollars to do too much. Hence, heuristic evaluation is one…

  11. Geographical distribution of the annual mean radon concentrations in primary schools of Southern Serbia – application of geostatistical methods

    International Nuclear Information System (INIS)

    Bossew, P.; Žunić, Z.S.; Stojanovska, Z.; Tollefsen, T.; Carpentieri, C.; Veselinović, N.; Komatina, S.; Vaupotič, J.; Simović, R.D.; Antignani, S.; Bochicchio, F.

    2014-01-01

    Between 2008 and 2011 a survey of radon ( 222 Rn) was performed in schools of several districts of Southern Serbia. Some results have been published previously (Žunić et al., 2010; Carpentieri et al., 2011; Žunić et al., 2013). This article concentrates on the geographical distribution of the measured Rn concentrations. Applying geostatistical methods we generate “school radon maps” of expected concentrations and of estimated probabilities that a concentration threshold is exceeded. The resulting maps show a clearly structured spatial pattern which appears related to the geological background. In particular in areas with vulcanite and granitoid rocks, elevated radon (Rn) concentrations can be expected. The “school radon map” can therefore be considered as proxy to a map of the geogenic radon potential, and allows identification of radon-prone areas, i.e. areas in which higher Rn radon concentrations can be expected for natural reasons. It must be stressed that the “radon hazard”, or potential risk, estimated this way, has to be distinguished from the actual radon risk, which is a function of exposure. This in turn may require (depending on the target variable which is supposed to measure risk) considering demographic and sociological reality, i.e. population density, distribution of building styles and living habits. -- Highlights: • A map of Rn concentrations in primary schools of Southern Serbia. • Application of geostatistical methods. • Correlation with geology found. • Can serve as proxy to identify radon prone areas

  12. Statistical Analyses of Second Indoor Bio-Release Field Evaluation Study at Idaho National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Amidan, Brett G.; Pulsipher, Brent A.; Matzke, Brett D.

    2009-12-17

    In September 2008 a large-scale testing operation (referred to as the INL-2 test) was performed within a two-story building (PBF-632) at the Idaho National Laboratory (INL). The report “Operational Observations on the INL-2 Experiment” defines the seven objectives for this test and discusses the results and conclusions. This is further discussed in the introduction of this report. The INL-2 test consisted of five tests (events) in which a floor (level) of the building was contaminated with the harmless biological warfare agent simulant Bg and samples were taken in most, if not all, of the rooms on the contaminated floor. After the sampling, the building was decontaminated, and the next test performed. Judgmental samples and probabilistic samples were determined and taken during each test. Vacuum, wipe, and swab samples were taken within each room. The purpose of this report is to study an additional four topics that were not within the scope of the original report. These topics are: 1) assess the quantitative assumptions about the data being normally or log-normally distributed; 2) evaluate differences and quantify the sample to sample variability within a room and across the rooms; 3) perform geostatistical types of analyses to study spatial correlations; and 4) quantify the differences observed between surface types and sampling methods for each scenario and study the consistency across the scenarios. The following four paragraphs summarize the results of each of the four additional analyses. All samples after decontamination came back negative. Because of this, it was not appropriate to determine if these clearance samples were normally distributed. As Table 1 shows, the characterization data consists of values between and inclusive of 0 and 100 CFU/cm2 (100 was the value assigned when the number is too numerous to count). The 100 values are generally much bigger than the rest of the data, causing the data to be right skewed. There are also a significant

  13. Modelagem geoestatística da infecção por Ascaris lumbricoides Geostatistical modeling of Ascaris lumbricoides infection

    Directory of Open Access Journals (Sweden)

    Bruno de Paula Menezes Drumond Fortes

    2004-06-01

    Full Text Available O estudo tem por objetivo modelar a distribuição espacial da ocorrência de ascaríase, utilizando mapas de risco mediante técnicas de geoprocessamento e análise geoestatística. Com base no banco de dados do PAISQUA, foram selecionados 19 setores censitários do Rio de Janeiro. Foram amostradas e georreferenciadas, no centróide de seu respectivo domicílio, 1.550 crianças com idade de 1 a 9 anos. Mapas de risco de Ascaris lumbricoides foram gerados usando krigagem indicadora. Com base na validação cruzada, os valores estimados foram comparados aos observados por intermédio da curva ROC. Um modelo de semivariograma isotrópico esférico com alcance de 30m e efeito pepita de 50% foi empregado na krigagem ordinária indicadora para a construção de um mapa de probabilidade de infecção por A. lumbricoides. A acurácia global, mensurada por meio da área sob a curva ROC, mostrou-se significativa. O uso da krigagem ordinária indicadora permitiu a modelagem de mapas de risco valendo-se da amostra de uma variável indicadora. O emprego das técnicas de análise estatística espacial mostrou-se adequado na predição da ocorrência do fenômeno, não ficando restrita a delimitações político-administrativas da região.The following study intends to model the spatial distribution of ascariasis, through the use of geoprocessing and geostatistic analysis. The database used in the study was taken from the PAISQUA project, including a coproparasitologic and domiciliary survey, conducted in 19 selected census tracts of Rio de Janeiro State, Brazil, randomly selecting a group of 1,550 children aged 1 to 9 years old plotting them in their respective domicile's centroids. Risk maps of Ascaris lumbricoides were generated by indicator kriging. The estimated and observed values from the cross-validation were compared using a ROC curve. An isotropic spherical semivariogram model with a range of 30m and nugget effect of 50% was employed in ordinary

  14. Economic evaluation of CISM : a pilot study

    DEFF Research Database (Denmark)

    Vogt, Joachim

    2004-01-01

    air traffic controllers, critical incident stress management, CISM, critical incidents, critical incident stress, cost-benefit-analysis, economic evaluation, efficiency, return on investment......air traffic controllers, critical incident stress management, CISM, critical incidents, critical incident stress, cost-benefit-analysis, economic evaluation, efficiency, return on investment...

  15. Feasibility study on evaluating driver education curriculum.

    Science.gov (United States)

    2009-04-01

    One way to attempt to reduce the problem of teen driving crashes is professional driver education. However, despite the : seemingly universal appeal of driver education, scientific evaluations have indicated that such programs generally do not : prod...

  16. Geostatistical and stratigraphic analysis of deltaic reservoirs from the Reconcavo Basin, Brazil; Analise estratigrafica e geoestatistica de reservatorios deltaicos da Bacia do Reconcavo (BA)

    Energy Technology Data Exchange (ETDEWEB)

    Soares, Carlos Moreira

    1997-07-01

    This study presents the characterization of the external geometry of deltaic oil reservoirs, including the description of their areal distribution using geo statistic tools, such as variography and kriging. A high-resolution stratigraphic study was developed over a 25 km{sup 2} area, by using data from 276 closely-spaced wells of an oil-producer field from the Reconcavo Basin, northeastern Brazil. The studied succession records the progressive lacustrine transgression of a deltaic environment. Core data and stratigraphic cross sections suggest that the oil reservoirs are mostly amalgamated, delta-front lobes, and subordinately, crevasse deposits. Some important geometrical elements were recognized by the detailed variographic analysis developed for each stratigraphic unit (zone). The average width for the groups of deltaic lobes of one zone was measured from the variographic feature informally named as hole effect. This procedure was not possible for the other zones due to the intense lateral amalgamation of sandstones, indicated by many variographic nested structures. Net sand krigged maps for the main zones suggest a NNW-SSE orientation for the deltaic lobes, as also their common amalgamation and compensation arrangements. High-resolution stratigraphic analyses should include a more regional characterization of the depositional system that comprises the studied succession. On the other hand, geostatistical studies should be developed only after the recognition of the depositional processes acting in the study area and the geological meaning of the variable to be treated, including its spatial variability scales as a function of sand body thickness, orientation and amalgamation. (author)

  17. Detection of Local Anomalies in High Resolution Hyperspectral Imagery Using Geostatistical Filtering and Local Spatial Statistics

    Science.gov (United States)

    Goovaerts, P.; Jacquez, G. M.; Marcus, A. W.

    2004-12-01

    Spatial data are periodically collected and processed to monitor, analyze and interpret developments in our changing environment. Remote sensing is a modern way of data collecting and has seen an enormous growth since launching of modern satellites and development of airborne sensors. In particular, the recent availability of high spatial resolution hyperspectral imagery (spatial resolution of less than 5 meters and including data collected over 64 or more bands of electromagnetic radiation for each pixel offers a great potential to significantly enhance environmental mapping and our ability to model spatial systems. High spatial resolution imagery contains a remarkable quantity of information that could be used to analyze spatial breaks (boundaries), areas of similarity (clusters), and spatial autocorrelation (associations) across the landscape. This paper addresses the specific issue of soil disturbance detection, which could indicate the presence of land mines or recent movements of troop and heavy equipment. A challenge presented by soil detection is to retain the measurement of fine-scale features (i.e. mineral soil changes, organic content changes, vegetation disturbance related changes, aspect changes) while still covering proportionally large spatial areas. An additional difficulty is that no ground data might be available for the calibration of spectral signatures, and little might be known about the size of patches of disturbed soils to be detected. This paper describes a new technique for automatic target detection which capitalizes on both spatial and across spectral bands correlation, does not require any a priori information on the target spectral signature but does not allow discrimination between targets. This approach involves successively a multivariate statistical analysis (principal component analysis) of all spectral bands, a geostatistical filtering of noise and regional background in the first principal components using factorial kriging, and

  18. Characterisation of contaminated metals using an advanced statistical toolbox - Geostatistical characterisation of contaminated metals: methodology and illustrations

    International Nuclear Information System (INIS)

    Larsson, Arne; Lidar, Per; Desnoyers, Yvon

    2014-01-01

    Radiological characterisation plays an important role in the process to recycle contaminated or potentially contaminated metals. It is a platform for planning, identification of the extent and nature of contamination, assessing potential risk impacts, cost estimation, radiation protection, management of material arising from decommissioning as well as for the release of the materials as well as the disposal of the generated secondary waste as radioactive waste. Key issues in radiological characterisation are identification of objectives, development of a measurement and sampling strategy (probabilistic, judgmental or a combination thereof), knowledge management, traceability, recording and processing of obtained information. By applying advanced combination of statistical and geostatistical in the concept better performance can be achieved at a lower cost. This paper will describe the benefits with the usage of the available methods in the different stages of the characterisation, treatment and clearance processes aiming for reliable results in line with the data quality objectives. (authors)

  19. Geostatistical Investigations of Displacements on the Basis of Data from the Geodetic Monitoring of a Hydrotechnical Object

    Science.gov (United States)

    Namysłowska-Wilczyńska, Barbara; Wynalek, Janusz

    2017-12-01

    Geostatistical methods make the analysis of measurement data possible. This article presents the problems directed towards the use of geostatistics in spatial analysis of displacements based on geodetic monitoring. Using methods of applied (spatial) statistics, the research deals with interesting and current issues connected to space-time analysis, modeling displacements and deformations, as applied to any large-area objects on which geodetic monitoring is conducted (e.g., water dams, urban areas in the vicinity of deep excavations, areas at a macro-regional scale subject to anthropogenic influences caused by mining, etc.). These problems are very crucial, especially for safety assessment of important hydrotechnical constructions, as well as for modeling and estimating mining damage. Based on the geodetic monitoring data, a substantial basic empirical material was created, comprising many years of research results concerning displacements of controlled points situated on the crown and foreland of an exemplary earth dam, and used to assess the behaviour and safety of the object during its whole operating period. A research method at a macro-regional scale was applied to investigate some phenomena connected with the operation of the analysed big hydrotechnical construction. Applying a semivariogram function enabled the spatial variability analysis of displacements. Isotropic empirical semivariograms were calculated and then, theoretical parameters of analytical functions were determined, which approximated the courses of the mentioned empirical variability measure. Using ordinary (block) kriging at the grid nodes of an elementary spatial grid covering the analysed object, the values of the Z* estimated means of displacements were calculated together with the accompanying assessment of uncertainty estimation - a standard deviation of estimation σk. Raster maps of the distribution of estimated averages Z* and raster maps of deviations of estimation σk (in perspective

  20. WMC Database Evaluation. Case Study Report

    Energy Technology Data Exchange (ETDEWEB)

    Palounek, Andrea P. T [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-10-29

    The WMC Database is ultimately envisioned to hold a collection of experimental data, design information, and information from computational models. This project was a first attempt at using the Database to access experimental data and extract information from it. This evaluation shows that the Database concept is sound and robust, and that the Database, once fully populated, should remain eminently usable for future researchers.

  1. Appraisal of family doctors: an evaluation study.

    NARCIS (Netherlands)

    Lewis, M.I.; Elwyn, G.; Wood, F.

    2003-01-01

    BACKGROUND: Appraisal has evolved to become a key component of workforce management. However, it is not clear from existing proposals for appraisal of doctors whether employers, health authorities or primary care organisations should take responsibility for appraisal processes. AIMS: To evaluate the

  2. Geostatistical screening of flood events in the groundwater levels of the diverted inner delta of the Danube River: implications for river bed clogging

    Science.gov (United States)

    Trásy, Balázs; Garamhegyi, Tamás; Laczkó-Dobos, Péter; Kovács, József; Hatvani, István Gábor

    2018-04-01

    The efficient operation of shallow groundwater (SGW) monitoring networks is crucial to water supply, in-land water protection, agriculture and nature conservation. In the present study, the spatial representativity of such a monitoring network in an area that has been thoroughly impacted by anthropogenic activity (river diversion/damming) is assessed, namely the Szigetköz adjacent to the River Danube. The main aims were to assess the spatial representativity of the SGW monitoring network in different discharge scenarios, and investigate the directional characteristics of this representativity, i.e. establish whether geostatistical anisotropy is present, and investigate how this changes with flooding. After the subtraction of a spatial trend from the time series of 85 shallow groundwater monitoring wells tracking flood events from 2006, 2009 and 2013, variography was conducted on the residuals, and the degree of anisotropy was assessed to explore the spatial autocorrelation structure of the network. Since the raw data proved to be insufficient, an interpolated grid was derived, and the final results were scaled to be representative of the original raw data. It was found that during floods the main direction of the spatial variance of the shallow groundwater monitoring wells alters, from perpendicular to the river to parallel with it for over a period of about two week. However, witht the passing of the flood, this returns to its original orientation in 2 months. It is likely that this process is related first to the fast removal of clogged riverbed strata by the flood, then to their slower replacement. In addition, the study highlights the importance of assessing the direction of the spatial autocorrelation structure of shallow groundwater monitoring networks, especially if the aim is to derive interpolated maps for the further investigation or modeling of flow.

  3. Evaluation of Social Studies Curriculum on Compassion ...

    African Journals Online (AJOL)

    This study examined the impact of social studies curriculum on the affective dispositions of students of Colleges of Education in North-West Zone of Nigeria. The purpose of the study was to determine the level of NCE I and NCE III students' affective dispositions in the area of compassion. One research question and one ...

  4. Evaluation of multi-outcome longitudinal studies

    DEFF Research Database (Denmark)

    Jensen, Signe Marie; Pipper, Christian Bressen; Ritz, Christian

    2015-01-01

    conservative conclusions. We propose an alternative approach for multiplicity adjustment that incorporates dependence between outcomes, resulting in an appreciably less conservative evaluation. The ability of the proposed method to control the familywise error rate is evaluated in a simulation study...

  5. Cooperative Student Assessment Method: an Evaluation Study

    Directory of Open Access Journals (Sweden)

    Antonella Grasso

    2006-06-01

    Full Text Available Training through the Internet poses a series of technical problems and pedagogical issues. Traditional training is not indiscriminate but takes on different forms according to the needs of the subject being trained and the context where such training occurs. In order to make the systems adaptable in this way, a model of the student’s characteristics - the student model - has to be set up, maintained and updated. However, there are many difficulties involved in obtaining sufficient information to create an accurate student model. One way to solve this problem is to involve students in the student modeling process, stimulating them to provide the necessary information by means of a dialog in which the student and system build the student model according to a collaborative process. The present work describes a cooperative student modeling method (Cooperative Student Assessment - CSA which builds a joint system-student assessment of student’s activities on the basis of the student’s self-assessment ability estimation and a prototype system for children, addressing the learning of fractions, in which CSA is implemented. The article also reports the result of an experimentation carried out with learners attending primary school aiming at evaluating the effectiveness of involving students in the assessment process by comparing two versions of the same system: one using cooperative student modeling and the other the traditional overlay model.

  6. Lesson Study: Evaluation Report and Executive Summary

    Science.gov (United States)

    Murphy, Richard; Weinhardt, Felix; Wyness, Gill; Rolfe, Heather

    2017-01-01

    Lesson Study is a popular approach to teacher professional development used widely in Japan. It involves a small group of teachers co-planning a series of lessons based on a shared learning goal for the pupils, with one teacher leading the co-constructed lesson and their colleagues invited to observe pupil learning in the lesson. The team then…

  7. QUALITY OF AN ACADEMIC STUDY PROGRAMME - EVALUATION MODEL

    Directory of Open Access Journals (Sweden)

    Mirna Macur

    2016-01-01

    Full Text Available Quality of an academic study programme is evaluated by many: employees (internal evaluation and by external evaluators: experts, agencies and organisations. Internal and external evaluation of an academic programme follow written structure that resembles on one of the quality models. We believe the quality models (mostly derived from EFQM excellence model don’t fit very well into non-profit activities, policies and programmes, because they are much more complex than environment, from which quality models derive from (for example assembly line. Quality of an academic study programme is very complex and understood differently by various stakeholders, so we present dimensional evaluation in the article. Dimensional evaluation, as opposed to component and holistic evaluation, is a form of analytical evaluation in which the quality of value of the evaluand is determined by looking at its performance on multiple dimensions of merit or evaluation criteria. First stakeholders of a study programme and their views, expectations and interests are presented, followed by evaluation criteria. They are both joined into the evaluation model revealing which evaluation criteria can and should be evaluated by which stakeholder. Main research questions are posed and research method for each dimension listed.

  8. Principals' Experiences of Being Evaluated: A Phenomenological Study

    Science.gov (United States)

    Parylo, Oksana; Zepeda, Sally J.; Bengtson, Ed

    2012-01-01

    This phenomenological study sought to understand principals' lived experiences of being evaluated with reliance on the principles of developmental supervision and adult learning theory. Analysis of interview data from 16 principals revealed 3 major constructs in principal evaluation: evaluation is a complex, constantly changing system; principal…

  9. Student Evaluation of Teaching: A Case Study from School of ...

    African Journals Online (AJOL)

    Purpose: This paper presents a case study of an academic department's experience with evaluation. The purpose is to review the impact of student evaluation of teaching. The paper also introduces a new evaluation scoring method: the University of Zambia Staff Appraisal System (UNZASAS) method. Method: Anonymous ...

  10. The geostatistics of the metal concentrations in sediments from the eastern Brazilian continental shelf in areas of gas and oil production

    Science.gov (United States)

    Aguiar, Jose Edvar; de Lacerda, Luiz Drude; Miguens, Flavio Costa; Marins, Rozane Valente

    2014-04-01

    Geostatistical techniques were used to evaluate the differences in the geochemistry of metals in the marine sediments along the Eastern Brazilian continental margin along the states of Ceará and Rio Grande do Norte (Northeastern sector) and Espírito Santo (Southeastern sector). The concentrations of Al, Fe, Mn, Ba, Cd, Cu, Cr, Ni, Pb, V, Hg, and Zn were obtained from acid digestion and quantified using flame atomic absorption spectrometry (AAS), inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma atomic emission spectrometry (ICP-AES). The metals showed a similar order of concentration: Al > Fe > Ba > Mn > V > Ni > Pb > Cr > Zn > Cu, in both the Ceará; and Rio Grande do Norte shelf regions but different in the Espírito Santo shelf (Fe > Al > Mn > Ba > Zn > V > Cr > Ni > Pb > Cu. The concentrations of Hg and Cd were below the detection limit in all areas. A multivariate analysis revealed that the metals of siliciclastic origin on the continental shelf of Ceará are carried by Al. In addition, a large portion of metal deposits is connected to the iron and manganese oxides on the continental margin of Rio Grande do Norte. The metals from the continental supply on the coast of Espírito Santo (Cu, Ni, Ba, and Mn) are associated with Al; whereas Cr, Pb, V, and Zn are associated with iron in this southern area. Geochemical evaluations are needed to distinguish the origin and mineralogical differences of marine sediments within the regions. Scanning electron microscopy/energy dispersive spectrometry (SEM/EDS) applied to the sediments from the coast of Ceará showed the morphological diversity of sediment grains: biological fragments, multifaceted particles, aggregates, and crystals occurred in the three regions analyzed. Among these grains, calcite, Mg-calcite, and aragonite were predominant in the northeastern sector, whereas silicates and other minerals were predominant the southeastern sector. Mg, K, Ti, and Zr as well as the

  11. A study protocol to evaluate the relationship between outdoor air pollution and pregnancy outcomes.

    Science.gov (United States)

    Ribeiro, Manuel C; Pereira, Maria J; Soares, Amílcar; Branquinho, Cristina; Augusto, Sofia; Llop, Esteve; Fonseca, Susana; Nave, Joaquim G; Tavares, António B; Dias, Carlos M; Silva, Ana; Selemane, Ismael; de Toro, Joaquin; Santos, Mário J; Santos, Fernanda

    2010-10-15

    The present study protocol is designed to assess the relationship between outdoor air pollution and low birth weight and preterm births outcomes performing a semi-ecological analysis. Semi-ecological design studies are widely used to assess effects of air pollution in humans. In this type of analysis, health outcomes and covariates are measured in individuals and exposure assignments are usually based on air quality monitor stations. Therefore, estimating individual exposures are one of the major challenges when investigating these relationships with a semi-ecologic design. Semi-ecologic study consisting of a retrospective cohort study with ecologic assignment of exposure is applied. Health outcomes and covariates are collected at Primary Health Care Center. Data from pregnant registry, clinical record and specific questionnaire administered orally to the mothers of children born in period 2007-2010 in Portuguese Alentejo Litoral region, are collected by the research team. Outdoor air pollution data are collected with a lichen diversity biomonitoring program, and individual pregnancy exposures are assessed with spatial geostatistical simulation, which provides the basis for uncertainty analysis of individual exposures. Awareness of outdoor air pollution uncertainty will improve validity of individual exposures assignments for further statistical analysis with multivariate regression models. Exposure misclassification is an issue of concern in semi-ecological design. In this study, personal exposures are assigned to each pregnant using geocoded addresses data. A stochastic simulation method is applied to lichen diversity values index measured at biomonitoring survey locations, in order to assess spatial uncertainty of lichen diversity value index at each geocoded address. These methods assume a model for spatial autocorrelation of exposure and provide a distribution of exposures in each study location. We believe that variability of simulated exposure values at

  12. A study protocol to evaluate the relationship between outdoor air pollution and pregnancy outcomes

    Directory of Open Access Journals (Sweden)

    Selemane Ismael

    2010-10-01

    Full Text Available Abstract Background The present study protocol is designed to assess the relationship between outdoor air pollution and low birth weight and preterm births outcomes performing a semi-ecological analysis. Semi-ecological design studies are widely used to assess effects of air pollution in humans. In this type of analysis, health outcomes and covariates are measured in individuals and exposure assignments are usually based on air quality monitor stations. Therefore, estimating individual exposures are one of the major challenges when investigating these relationships with a semi-ecologic design. Methods/Design Semi-ecologic study consisting of a retrospective cohort study with ecologic assignment of exposure is applied. Health outcomes and covariates are collected at Primary Health Care Center. Data from pregnant registry, clinical record and specific questionnaire administered orally to the mothers of children born in period 2007-2010 in Portuguese Alentejo Litoral region, are collected by the research team. Outdoor air pollution data are collected with a lichen diversity biomonitoring program, and individual pregnancy exposures are assessed with spatial geostatistical simulation, which provides the basis for uncertainty analysis of individual exposures. Awareness of outdoor air pollution uncertainty will improve validity of individual exposures assignments for further statistical analysis with multivariate regression models. Discussion Exposure misclassification is an issue of concern in semi-ecological design. In this study, personal exposures are assigned to each pregnant using geocoded addresses data. A stochastic simulation method is applied to lichen diversity values index measured at biomonitoring survey locations, in order to assess spatial uncertainty of lichen diversity value index at each geocoded address. These methods assume a model for spatial autocorrelation of exposure and provide a distribution of exposures in each study location

  13. Characterization of Drain Surface Water: Environmental Profile, Degradation Level and Geo-statistic Monitoring

    Directory of Open Access Journals (Sweden)

    Muhammad Waseem Mumtaz

    2015-12-01

    Full Text Available The physico-chemical characterization of the surface water. Samples was carried out collected from nine sampling points of drain passing by the territory of Hafizabad city, Punjab, Pakistan. The water of drain is used by farmers for irrigation purposes in nearby agricultural fields. Twenty water quality parameters were evaluated in three turns and the results obtained were compared with the National Environmental Quality Standards (NEQS municipal and industrial effluents prescribed limits. The highly significant difference (p0.05 was noted for temperature, pH, electrical conductivity, hardness, calcium, sodium, chemical oxygen demand and chloride among water samples from different sampling points. Furthermore, the experimental results of different water quality parameters studied at nine sampling points of the drain were used and interpolated in ArcGIS 9.3 environment system using kriging techniques to obtain calculated values for the remaining locations of the Drain.

  14. Bias During the Evaluation of Animal Studies?

    Directory of Open Access Journals (Sweden)

    Andrew Knight

    2012-02-01

    Full Text Available My recent book entitled The Costs and Benefits of Animal Experiments seeks to answer a key question within animal ethics, namely: is animal experimentation ethically justifiable? Or, more precisely, is it justifiable within the utilitarian cost:benefit framework that fundamentally underpins most regulations governing animal experimentation? To answer this question I reviewed more than 500 scientific publications describing animal studies, animal welfare impacts, and alternative research, toxicity testing and educational methodologies. To minimise bias I focused primarily on large-scale systematic reviews that had examined the human clinical and toxicological utility of animal studies. Despite this, Dr. Susanne Prankel recently reviewed my book in this journal, essentially accusing me of bias. However, she failed to provide any substantive evidence to refute my conclusions, let alone evidence of similar weight to that on which they are based. Those conclusions are, in fact, firmly based on utilitarian ethical reasoning, informed by scientific evidence of considerable strength, and I believe they are robust.

  15. Geostatistical analysis of the effects of stage and roughness on reach-scale spatial patterns of velocity and turbulence intensity

    Science.gov (United States)

    Legleiter, Carl J.; Phelps, Tracy L.; Wohl, Ellen E.

    2007-01-01

    Although previous research has documented well-organized interactions between the turbulent flow field and an irregular boundary, the spatial variability of turbulent flow characteristics at the reach-scale remains poorly understood. In this paper, we present detailed field measurements of three-dimensional flow velocities and turbulence intensities in a high-gradient, cobble-bed riffle from three discharges; additional data on sediment grain size and bed topography were used to characterize boundary roughness. An acoustic Doppler velocimeter was used to measure velocities along five cross-sections within a 6 m long reach of the North Fork Cache La Poudre River; vertical profiles were also measured along the channel thalweg. We adopted a spatially explicit stochastic hydraulic approach and focused not on coherent flow structures per se but rather time-averaged, reach-scale variability and spatial pattern. Scaling velocities and turbulence intensities by the reach-averaged friction velocity U* accounted for changes in flow depth and enabled comparisons among the three discharges. We quantified the effects of stage and roughness by assessing differences among probability distributions of hydraulic quantities and by examining geostatistical metrics of spatial variability. We computed semivariograms for streamwise and transverse directions and fit parametric models to summarize the spatial structure of each variable at each discharge. Cross-correlograms were also used to describe the local and lagged effects of boundary roughness on flow characteristics. Although the probability distributions yielded some insight, incorporating spatial information revealed important elements of stage-dependent flow structure. The development of secondary currents and flow convergence at higher stages were clearly documented in maps and semivariograms. In general, the spatial structure of the flow field became smoother and more continuous as stage increased and the effects of boundary

  16. Hierarchical probabilistic regionalization of volcanism for Sengan region in Japan using multivariate statistical techniques and geostatistical interpolation techniques

    International Nuclear Information System (INIS)

    Park, Jinyong; Balasingham, P.; McKenna, Sean Andrew; Kulatilake, Pinnaduwa H. S. W.

    2004-01-01

    Sandia National Laboratories, under contract to Nuclear Waste Management Organization of Japan (NUMO), is performing research on regional classification of given sites in Japan with respect to potential volcanic disruption using multivariate statistics and geo-statistical interpolation techniques. This report provides results obtained for hierarchical probabilistic regionalization of volcanism for the Sengan region in Japan by applying multivariate statistical techniques and geostatistical interpolation techniques on the geologic data provided by NUMO. A workshop report produced in September 2003 by Sandia National Laboratories (Arnold et al., 2003) on volcanism lists a set of most important geologic variables as well as some secondary information related to volcanism. Geologic data extracted for the Sengan region in Japan from the data provided by NUMO revealed that data are not available at the same locations for all the important geologic variables. In other words, the geologic variable vectors were found to be incomplete spatially. However, it is necessary to have complete geologic variable vectors to perform multivariate statistical analyses. As a first step towards constructing complete geologic variable vectors, the Universal Transverse Mercator (UTM) zone 54 projected coordinate system and a 1 km square regular grid system were selected. The data available for each geologic variable on a geographic coordinate system were transferred to the aforementioned grid system. Also the recorded data on volcanic activity for Sengan region were produced on the same grid system. Each geologic variable map was compared with the recorded volcanic activity map to determine the geologic variables that are most important for volcanism. In the regionalized classification procedure, this step is known as the variable selection step. The following variables were determined as most important for volcanism: geothermal gradient, groundwater temperature, heat discharge, groundwater

  17. Evaluation and comparison of methods to estimate irrigation withdrawal for the National Water Census Focus Area Study of the Apalachicola-Chattahoochee-Flint River Basin in southwestern Georgia

    Science.gov (United States)

    Painter, Jaime A.; Torak, Lynn J.; Jones, John W.

    2015-09-30

    Methods to estimate irrigation withdrawal using nationally available datasets and techniques that are transferable to other agricultural regions were evaluated by the U.S. Geological Survey as part of the Apalachicola-Chattahoochee-Flint (ACF) River Basin focus area study of the National Water Census (ACF–FAS). These methods investigated the spatial, temporal, and quantitative distributions of water withdrawal for irrigation in the southwestern Georgia region of the ACF–FAS, filling a vital need to inform science-based decisions regarding resource management and conservation. The crop– demand method assumed that only enough water is pumped onto a crop to satisfy the deficit between evapotranspiration and precipitation. A second method applied a geostatistical regimen of variography and conditional simulation to monthly metered irrigation withdrawal to estimate irrigation withdrawal where data do not exist. A third method analyzed Landsat satellite imagery using an automated approach to generate monthly estimates of irrigated lands. These methods were evaluated independently and compared collectively with measured water withdrawal information available in the Georgia part of the ACF–FAS, principally in the Chattahoochee-Flint River Basin. An assessment of each method’s contribution to the National Water Census program was also made to identify transfer value of the methods to the national program and other water census studies. None of the three methods evaluated represent a turnkey process to estimate irrigation withdrawal on any spatial (local or regional) or temporal (monthly or annual) extent. Each method requires additional information on agricultural practices during the growing season to complete the withdrawal estimation process. Spatial and temporal limitations inherent in identifying irrigated acres during the growing season, and in designing spatially and temporally representative monitor (meter) networks, can belie the ability of the methods to

  18. Trends in Evaluation Research 1982 - 2002: A Study on how the Quality of IT Evaluation Studies Develop

    NARCIS (Netherlands)

    de Keizer, Nicolette; Ammenwerth, Elske

    2005-01-01

    During the last years the significance of evaluation studies as well as the interest in adequate methods and approaches for evaluation has grown in medical informatics. In order to put this discussion into historical perspective of evaluation research, we conducted a systematic review on trends in

  19. Geostatistical exploration of spatial variation of summertime temperatures in the Detroit metropolitan region

    Science.gov (United States)

    Zhang, Kai; Oswald, Evan M.; Brown, Daniel G.; Brines, Shannon J.; Gronlund, Carina J.; White-Newsome, Jalonne L.; Rood, Richard B.; O’Neill, Marie S.

    2015-01-01

    Background Because of the warming climate urban temperature patterns have been receiving increased attention. Temperature within urban areas can vary depending on land cover, meteorological and other factors. High resolution satellite data can be used to understand this intra-urban variability, although they have been primarily studied to characterize urban heat islands at a larger spatial scale. Objective This study examined whether satellite-derived impervious surface and meteorological conditions from multiple sites can improve characterization of spatial variability of temperature within an urban area. Methods Temperature was measured at 17 outdoor sites throughout the Detroit metropolitan area during the summer of 2008. Kriging and linear regression were applied to daily temperatures and secondary information, including impervious surface and distance-to-water. Performance of models in predicting measured temperatures was evaluated by cross-validation. Variograms derived from several scenarios were compared to determine whether high-resolution impervious surface information could capture fine-scale spatial structure of temperature in the study area. Results Temperatures measured at the sites were significantly different from each other, and all kriging techniques generally performed better than the two linear regression models. Impervious surface values and distance-to-water generally improved predictions slightly. Restricting models to days with lake breezes and with less cloud cover also somewhat improved the predictions. In addition, incorporating high-resolution impervious surface information into cokriging or universal kriging enhanced the ability to characterize fine-scale spatial structure of temperature. Conclusions Meteorological and satellite-derived data can better characterize spatial variability in temperature across a metropolitan region. The data sources and methods we used can be applied in epidemiological studies and public health

  20. To evaluate or not: Evaluability study of 40 interventions of Belgian development cooperation.

    Science.gov (United States)

    Holvoet, Nathalie; Van Esbroeck, Dirk; Inberg, Liesbeth; Popelier, Lisa; Peeters, Bob; Verhofstadt, Ellen

    2018-04-01

    Due to an increasing importance of evaluations within development cooperation, it has become all the more important to analyse if initial conditions for quality and relevant evaluations are met. This article presents the findings from an evaluability study of 40 interventions of Belgian development cooperation. A study framework was developed focusing on three key dimensions (i.e. theoretical evaluability, practical evaluability and the evaluation context) and subdivided over the different OECD/DAC criteria. Drawing upon a combination of desk and field research, the study framework was subsequently applied on a set of 40 interventions in Benin, DRC, Rwanda and Belgium. Findings highlight that the context dimension scores remarkably better than the theoretical and practical evaluability in particular. The large majority of the interventions have the conditions in place to satisfactorily evaluate effectiveness and efficiency while the opposite holds for sustainability and impact in particular. These findings caution against commissioning of evaluations that ritually focus on all OECD/DAC criteria regardless of their readiness. It underscores the usefulness of a flexible 'portfolio' approach towards evaluations, in which a more systematic use of evaluability assessment from the start of interventions could play a role. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Análise dos atributos do solo e da produtividade da cultura de cana-de-açúcar com o uso da geoestatística e árvore de decisão Analyze the soil attributes and sugarcane yield culture with the use of geostatistics and decision trees

    Directory of Open Access Journals (Sweden)

    Zigomar Menezes de Souza

    2010-04-01

    Full Text Available Um dos desafios da agricultura de precisão é oferecer subsídios para a definição de unidades de manejo para posteriores intervenções. Portanto, o objetivo deste trabalho foi avaliar os atributos químicos do solo e a produtividade da cultura de cana-de-açúcar por meio da geoestatística e mineração de dados pela indução da árvore de decisão. A produtividade da cana-de-açúcar foi mapeada em uma área de aproximadamente 23ha, utilizando-se o critério de célula, por meio de um monitor de produtividade que permitiu a elaboração de um mapa digital que representa a superfície de produção para a área em estudo. Para determinar os atributos de um Argissolo Vermelho-Amarelo, foram coletadas as amostras no início da safra 2006/2007, utilizando-se uma grade regular de 50 x 50m, nas profundidades de 0,0-0,2m e 0,2-0,4m. Os dados dos atributos do solo e da produtividade foram analisados por meio da técnica de goestatística e classificados em três níveis de produção para indução de árvore de decisão. A árvore de decisão foi induzida no programa SAS Enterprise Miner, sendo utilizado algoritmo baseado na redução de entropia. As variáveis altitude e potássio apresentaram os maiores valores de correlação com a produtividade de cana-de-açúcar. A indução de árvores de decisão permitiu verificar que a altitude é a variável com maior potencial para interpretar os mapas de produtividade de cana-de-açúcar, auxiliando na agricultura de precisão e mostrando-se uma ferramenta adequada para o estudo de definição de zonas de manejo em área cultivada com essa cultura.One of the challenges of precision agriculture is to offer subsidies for the definition of management units for posterior interventions. Therefore, the objective of this work was to evaluate soil chemical attributes and sugarcane yield with the use of geostatistics and data mining by decision tree induction. Sugarcane yield was mapped in a 23ha field

  2. Geostatistical analysis of the power-law exponents of the size distribution of earthquakes, Quaternary faults and monogenetic volcanoes in the Central Trans-Mexican Volcanic Belt

    Science.gov (United States)

    Mendoza-Ponce, A.; Perez Lopez, R.; Guardiola-Albert, C.; Garduño-Monroy, V. H.; Figueroa-Soto, Á.

    2017-12-01

    The Trans Mexican Volcanic Belt (TMVB) is related to the convergence between the Cocos and Rivera plates beneath the North American plate by the Middle America Trench (MAT). Moreover, there is also intraplate faulting within the TMVB, which is responsible of important earthquakes like the Acambay in 1912 (Mw 7.0) and Maravatío in 1979 (Mb 5.3). In this tectonic scheme, monogenetic volcanoes, active faulting and earthquakes configure a complex tectonic frame where different spatial anisotropy featured this activity. This complexity can be characterized by the power-law of the frequency-size distribution of the monogenetic volcanoes, the faults and the earthquakes. This power-law is determined by the b-value of the Gutenberg-Richter law in case of the earthquakes. The novelty of this work is the application of geostatistics techniques (variograms) for the analysis of spatial distribution of the b-values obtained from the size distribution of the basal diameter for monogenetic volcanoes in the Michoacán-Guanajuato Volcanic Field (bmv), surface area for faults in the Morelia-Acambay fault system (bf) and the seismicity in the Central TMVB (beq). Therefore, the anisotropy in each case was compared and a geometric tectonic model was proposed. The evaluation of the spatial distribution of the b-value maps gives us a general interpretation of the tectonic stress field and the seismic hazard in the zone. Hence, the beq-value map for the seismic catalog shows anomalously low and high values, reveling two different processes, one related to a typical tectonic rupture (low b-values) and the other one related to hydraulic fracturing (high b-values). The resulting bmv-map for the diameter basal cones indicates us the locations of the ages of the monogenetic volcanoes, giving important information about the volcanic hazard. High bmv-values are correlated with the presence of young cinder cones and an increasing probability of a new volcano. For the Morelia-Acambay fault system

  3. Evaluation of the Ramazzini Foundation Study of Methanol in Rats

    Science.gov (United States)

    Evaluation of the Ramazzini Foundation Study of Methanol in Rats: A Comparison of Diagnoses by the RF Study Pathologist and a Recent NTP Review Team, summarized by George Cruzan and submitted to the Methanol Institute

  4. Simulation Studies for the evaluation of health information technologies:

    DEFF Research Database (Denmark)

    Ammenwerth, Elske; Hackl, Werner O; Binzer, Kristine

    2012-01-01

    It is essential for new health information technologies (IT) to undergo rigorous evaluations to ensure they are effective and safe for use in real-world situations. However, evaluation of new health IT is challenging, as field studies are often not feasible when the technology being evaluated...... of participants before using unfamiliar applications; consideration of time, effort and costs of conducting the simulation; technical maturity of the evaluated system; and allowing adequate preparation of simulation scenarios and simulation setting. Simulation studies are an interesting but time......-consuming approach, which can be used to evaluate newly developed health IT systems, particularly those systems that are not yet suffi ciently mature to undergo field evaluation studies....

  5. Geostatistical evaluation of integrated marsh management impact on mosquito vectors using before-after-control-impact (BACI) design

    OpenAIRE

    Rochlin, Ilia; Iwanejko, Tom; Dempsey, Mary E; Ninivaggi, Dominick V

    2009-01-01

    Abstract Background In many parts of the world, salt marshes play a key ecological role as the interface between the marine and the terrestrial environments. Salt marshes are also exceedingly important for public health as larval habitat for mosquitoes that are vectors of disease and significant biting pests. Although grid ditching and pesticides have been effective in salt marsh mosquito control, marsh degradation and other environmental considerations compel a different approach. Targeted h...

  6. What have we learned from deterministic geostatistics at highly resolved field sites, as relevant to mass transport processes in sedimentary aquifers?

    Science.gov (United States)

    Ritzi, Robert W.; Soltanian, Mohamad Reza

    2015-12-01

    In the method of deterministic geostatistics (sensu Isaaks and Srivastava, 1988), highly-resolved data sets are used to compute sample spatial-bivariate statistics within a deterministic framework. The general goal is to observe what real, highly resolved, sample spatial-bivariate correlation looks like when it is well-quantified in naturally-occurring sedimentary aquifers. Furthermore, it is to understand how this correlation structure, (i.e. shape and correlation range) is related to independent and physically quantifiable attributes of the sedimentary architecture. The approach has evolved among work by Rubin (1995, 2003), Barrash and Clemo (2002), Ritzi et al. (2004, 2007, 2013), Dai et al. (2005), and Ramanathan et al. (2010). In this evolution, equations for sample statistics have been developed which allow tracking the facies types at the heads and tails of lag vectors. The goal is to observe and thereby understand how aspects of the sedimentary architecture affect the well-supported sample statistics. The approach has been used to study heterogeneity at a number of sites, representing a variety of depositional environments, with highly resolved data sets. What have we learned? We offer and support an opinion that the single most important insight derived from these studies is that the structure of spatial-bivariate correlation is essentially the cross-transition probability structure, determined by the sedimentary architecture. More than one scale of hierarchical sedimentary architecture has been represented in these studies, and a hierarchy of cross-transition probability structures was found to define the correlation structure in all cases. This insight allows decomposing contributions from different scales of the sedimentary architecture, and has led to a more fundamental understanding of mass transport processes including mechanical dispersion of solutes within aquifers, and the time-dependent retardation of reactive solutes. These processes can now be

  7. Evaluation of operational experience for the German safety study

    International Nuclear Information System (INIS)

    Lindauer, E.

    1977-01-01

    The proceeding of evaluation of nuclear reactor operating experiences for the German risk study is shown together with an intermediate state of the works. For foreign experiences readily available reports are used instead of own evaluations. For German reactors the available abnormal occurrences are investigated especially with regard to qualitative information. In addition, a detailed evaluation of operating data for Biblis A and B is carried out. (orig.) [de

  8. A Study on Developing Evaluation Criteria for Electronic Resources in Evaluation Indicators of Libraries

    Science.gov (United States)

    Noh, Younghee

    2010-01-01

    This study aimed to improve the current state of electronic resource evaluation in libraries. While the use of Web DB, e-book, e-journal, and other e-resources such as CD-ROM, DVD, and micro materials is increasing in libraries, their use is not comprehensively factored into the general evaluation of libraries and may diminish the reliability of…

  9. A Qualitative Study on Primary School Mathematics Lesson Evaluation

    Science.gov (United States)

    Zhao, Dongchen; Ma, Yunpeng

    2009-01-01

    Through the qualitative interviews of five implementers of primary school mathematics curriculum, this study addresses the ways in which mathematics lessons are evaluated. Results show that each evaluator recognizes different aspects of a "good lesson," however, among all criteria, the design of the lesson plan, realization of the lesson…

  10. Synthesis, evaluation and molecular modelling studies of some ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 122; Issue 2. Synthesis, evaluation and molecular modelling studies of some novel 3-(3 ... The compounds have been characterized on the basis of elemental analysis and spectral data. All the compounds were evaluated for their HIV-1 RT inhibitory activity. Among ...

  11. Study on the evaluation index of active power reserve

    Science.gov (United States)

    Guo, Xiaorui; Liu, Jiantao; Wang, Ke; Min, Lu

    2018-01-01

    Based on the role of active reserve at different time scales, divides the evaluation dimension of active reserve. Analysis the calculation principle of traditional reliability index such as probability of system safety, lack of power shortage and electricity shortage expectancy, and studies the applicability of these indicators to evaluate the reserve capacity on different dimensions. Resolves the evaluation index of active reserve capacity from the dimensions of time dimension, spatial dimension, system state, risk degree and economy, then construct evaluation index of active reserve capacity.

  12. Continuous Evaluation in Ethics Education: A Case Study.

    Science.gov (United States)

    McIntosh, Tristan; Higgs, Cory; Mumford, Michael; Connelly, Shane; DuBois, James

    2017-06-14

    A great need for systematic evaluation of ethics training programs exists. Those tasked with developing an ethics training program may be quick to dismiss the value of training evaluation in continuous process improvement. In the present effort, we use a case study approach to delineate how to leverage formative and summative evaluation measures to create a high-quality ethics education program. With regard to formative evaluation, information bearing on trainee reactions, qualitative data from the comments of trainees, in addition to empirical findings, can ensure that the training program operates smoothly. Regarding summative evaluation, measures examining trainee cognition, behavior, and organization-level results provide information about how much trainees have changed as a result of taking the ethics training. The implications of effective training program evaluation are discussed.

  13. A case study evaluation of the use of video technology in concrete pavement evaluation.

    Science.gov (United States)

    2000-01-01

    This report presents the results of an evaluation of video technology as a possible solution to the problem of safely collecting objective condition data for prioritizing concrete pavement rehabilitation needs in Virginia. The study involved the eval...

  14. Comparative study of heuristic evaluation and usability testing methods.

    Science.gov (United States)

    Thyvalikakath, Thankam Paul; Monaco, Valerie; Thambuganipalle, Himabindu; Schleyer, Titus

    2009-01-01

    Usability methods, such as heuristic evaluation, cognitive walk-throughs and user testing, are increasingly used to evaluate and improve the design of clinical software applications. There is still some uncertainty, however, as to how those methods can be used to support the development process and evaluation in the most meaningful manner. In this study, we compared the results of a heuristic evaluation with those of formal user tests in order to determine which usability problems were detected by both methods. We conducted heuristic evaluation and usability testing on four major commercial dental computer-based patient records (CPRs), which together cover 80% of the market for chairside computer systems among general dentists. Both methods yielded strong evidence that the dental CPRs have significant usability problems. An average of 50% of empirically-determined usability problems were identified by the preceding heuristic evaluation. Some statements of heuristic violations were specific enough to precisely identify the actual usability problem that study participants encountered. Other violations were less specific, but still manifested themselves in usability problems and poor task outcomes. In this study, heuristic evaluation identified a significant portion of problems found during usability testing. While we make no assumptions about the generalizability of the results to other domains and software systems, heuristic evaluation may, under certain circumstances, be a useful tool to determine design problems early in the development cycle.

  15. Guidance for Identifying, Selecting and Evaluating Open Literature Studies

    Science.gov (United States)

    This guidance for Office of Pesticide Program staff will assist in their evaluation of open literature studies of pesticides. It also describes how we identify, select, and ensure that data we use in risk assessments is of sufficient scientific quality.

  16. Inference of strata separation and gas emission paths in longwall overburden using continuous wavelet transform of well logs and geostatistical simulation

    Science.gov (United States)

    Karacan, C. Özgen; Olea, Ricardo A.

    2014-06-01

    Prediction of potential methane emission pathways from various sources into active mine workings or sealed gobs from longwall overburden is important for controlling methane and for improving mining safety. The aim of this paper is to infer strata separation intervals and thus gas emission pathways from standard well log data. The proposed technique was applied to well logs acquired through the Mary Lee/Blue Creek coal seam of the Upper Pottsville Formation in the Black Warrior Basin, Alabama, using well logs from a series of boreholes aligned along a nearly linear profile. For this purpose, continuous wavelet transform (CWT) of digitized gamma well logs was performed by using Mexican hat and Morlet, as the mother wavelets, to identify potential discontinuities in the signal. Pointwise Hölder exponents (PHE) of gamma logs were also computed using the generalized quadratic variations (GQV) method to identify the location and strength of singularities of well log signals as a complementary analysis. PHEs and wavelet coefficients were analyzed to find the locations of singularities along the logs. Using the well logs in this study, locations of predicted singularities were used as indicators in single normal equation simulation (SNESIM) to generate equi-probable realizations of potential strata separation intervals. Horizontal and vertical variograms of realizations were then analyzed and compared with those of indicator data and training image (TI) data using the Kruskal-Wallis test. A sum of squared differences was employed to select the most probable realization representing the locations of potential strata separations and methane flow paths. Results indicated that singularities located in well log signals reliably correlated with strata transitions or discontinuities within the strata. Geostatistical simulation of these discontinuities provided information about the location and extents of the continuous channels that may form during mining. If there is a gas

  17. Geostatistical modelling of malaria indicator survey data to assess the effects of interventions on the geographical distribution of malaria prevalence in children less than 5 years in Uganda.

    Science.gov (United States)

    Ssempiira, Julius; Nambuusi, Betty; Kissa, John; Agaba, Bosco; Makumbi, Fredrick; Kasasa, Simon; Vounatsou, Penelope

    2017-01-01

    Malaria burden in Uganda has declined disproportionately among regions despite overall high intervention coverage across all regions. The Uganda Malaria Indicator Survey (MIS) 2014-15 was the second nationally representative survey conducted to provide estimates of malaria prevalence among children less than 5 years, and to track the progress of control interventions in the country. In this present study, 2014-15 MIS data were analysed to assess intervention effects on malaria prevalence in Uganda among children less than 5 years, assess intervention effects at regional level, and estimate geographical distribution of malaria prevalence in the country. Bayesian geostatistical models with spatially varying coefficients were used to determine the effect of interventions on malaria prevalence at national and regional levels. Spike-and-slab variable selection was used to identify the most important predictors and forms. Bayesian kriging was used to predict malaria prevalence at unsampled locations. Indoor Residual Spraying (IRS) and Insecticide Treated Nets (ITN) ownership had a significant but varying protective effect on malaria prevalence. However, no effect was observed for Artemisinin Combination-based Therapies (ACTs). Environmental factors, namely, land cover, rainfall, day and night land surface temperature, and area type were significantly associated with malaria prevalence. Malaria prevalence was higher in rural areas, increased with the child's age, and decreased with higher household socioeconomic status and higher level of mother's education. The highest prevalence of malaria in children less than 5 years was predicted for regions of East Central, North East and West Nile, whereas the lowest was predicted in Kampala and South Western regions, and in the mountainous areas in Mid-Western and Mid-Eastern regions. IRS and ITN ownership are important interventions against malaria prevalence in children less than 5 years in Uganda. The varying effects of the

  18. Geostatistical modelling of malaria indicator survey data to assess the effects of interventions on the geographical distribution of malaria prevalence in children less than 5 years in Uganda.

    Directory of Open Access Journals (Sweden)

    Julius Ssempiira

    Full Text Available Malaria burden in Uganda has declined disproportionately among regions despite overall high intervention coverage across all regions. The Uganda Malaria Indicator Survey (MIS 2014-15 was the second nationally representative survey conducted to provide estimates of malaria prevalence among children less than 5 years, and to track the progress of control interventions in the country. In this present study, 2014-15 MIS data were analysed to assess intervention effects on malaria prevalence in Uganda among children less than 5 years, assess intervention effects at regional level, and estimate geographical distribution of malaria prevalence in the country.Bayesian geostatistical models with spatially varying coefficients were used to determine the effect of interventions on malaria prevalence at national and regional levels. Spike-and-slab variable selection was used to identify the most important predictors and forms. Bayesian kriging was used to predict malaria prevalence at unsampled locations.Indoor Residual Spraying (IRS and Insecticide Treated Nets (ITN ownership had a significant but varying protective effect on malaria prevalence. However, no effect was observed for Artemisinin Combination-based Therapies (ACTs. Environmental factors, namely, land cover, rainfall, day and night land surface temperature, and area type were significantly associated with malaria prevalence. Malaria prevalence was higher in rural areas, increased with the child's age, and decreased with higher household socioeconomic status and higher level of mother's education. The highest prevalence of malaria in children less than 5 years was predicted for regions of East Central, North East and West Nile, whereas the lowest was predicted in Kampala and South Western regions, and in the mountainous areas in Mid-Western and Mid-Eastern regions.IRS and ITN ownership are important interventions against malaria prevalence in children less than 5 years in Uganda. The varying

  19. Investigation of spatial correlation in MR images of human cerebral white matter using geostatistical methods

    Energy Technology Data Exchange (ETDEWEB)

    Keil, Fabian

    2014-03-20

    Investigating the structure of human cerebral white matter is gaining interest in the neurological as well as in the neuroscientific community. It has been demonstrated in many studies that white matter is a very dynamic structure, rather than a static construct which does not change for a lifetime. That means, structural changes within white matter can be observed even on short timescales, e.g. in the course of normal ageing, neurodegenerative diseases or even during learning processes. To investigate these changes, one method of choice is the texture analysis of images obtained from white matter. In this regard, MRI plays a distinguished role as it provides a completely non-invasive way of acquiring in vivo images of human white matter. This thesis adapted a statistical texture analysis method, known as variography, to quantify the spatial correlation of human cerebral white matter based on MR images. This method, originally introduced in geoscience, relies on the idea of spatial correlation in geological phenomena: in naturally grown structures near things are correlated stronger to each other than distant things. This work reveals that the geological principle of spatial correlation can be applied to MR images of human cerebral white matter and proves that variography is an adequate method to quantify alterations therein. Since the process of MRI data acquisition is completely different to the measuring process used to quantify geological phenomena, the variographic analysis had to be adapted carefully to MR methods in order to provide a correctly working methodology. Therefore, theoretical considerations were evaluated with numerical samples in a first, and validated with real measurements in a second step. It was shown that MR variography facilitates to reduce the information stored in the texture of a white matter image to a few highly significant parameters, thereby quantifying heterogeneity and spatial correlation distance with an accuracy better than 5

  20. Investigation of spatial correlation in MR images of human cerebral white matter using geostatistical methods

    International Nuclear Information System (INIS)

    Keil, Fabian

    2014-01-01

    Investigating the structure of human cerebral white matter is gaining interest in the neurological as well as in the neuroscientific community. It has been demonstrated in many studies that white matter is a very dynamic structure, rather than a static construct which does not change for a lifetime. That means, structural changes within white matter can be observed even on short timescales, e.g. in the course of normal ageing, neurodegenerative diseases or even during learning processes. To investigate these changes, one method of choice is the texture analysis of images obtained from white matter. In this regard, MRI plays a distinguished role as it provides a completely non-invasive way of acquiring in vivo images of human white matter. This thesis adapted a statistical texture analysis method, known as variography, to quantify the spatial correlation of human cerebral white matter based on MR images. This method, originally introduced in geoscience, relies on the idea of spatial correlation in geological phenomena: in naturally grown structures near things are correlated stronger to each other than distant things. This work reveals that the geological principle of spatial correlation can be applied to MR images of human cerebral white matter and proves that variography is an adequate method to quantify alterations therein. Since the process of MRI data acquisition is completely different to the measuring process used to quantify geological phenomena, the variographic analysis had to be adapted carefully to MR methods in order to provide a correctly working methodology. Therefore, theoretical considerations were evaluated with numerical samples in a first, and validated with real measurements in a second step. It was shown that MR variography facilitates to reduce the information stored in the texture of a white matter image to a few highly significant parameters, thereby quantifying heterogeneity and spatial correlation distance with an accuracy better than 5

  1. Evaluation systems for clinical governance development: a comparative study.

    Science.gov (United States)

    Hooshmand, Elaheh; Tourani, Sogand; Ravaghi, Hamid; Ebrahimipour, Hossein

    2014-01-01

    Lack of scientific and confirmed researches and expert knowledge about evaluation systems for clinical governance development in Iran have made studies on different evaluation systems for clinical governance development a necessity. These studies must provide applied strategies to design criteria of implementing clinical governance for hospital's accreditation. This is a descriptive and comparative study on development of clinical governance models all over the world. Data have been gathered by reviewing related articles. Models have been studied in comprehensive review method. The evaluated models of clinical governance development were Australian, NHS, SPOCK and OPTIGOV. The final aspects extracted from these models were Responsiveness, Policies and Strategies, Organizational Structure, Allocating Resources, Education and Occupational Development, Performance Evaluation, External Evaluation, Patient Oriented Approach, Risk Management, Personnel's Participation, Information Technology, Human Resources, Research and Development, Evidence Based Medicine, Clinical Audit, Health Technology Assessment and Quality. These results are applicable for completing the present criteria which evaluating clinical governance application and provide practical framework to evaluate country's hospital on the basis of clinical governance elements.

  2. Evaluation of School Uniform Policy in Turkey: A Case Study

    Science.gov (United States)

    Cinoglu, Mustafa

    2014-01-01

    The purpose of this study is to evaluate the results of current school uniform policies according to views of stakeholders. Descriptive case study method was used for this study to understand the concerns of the stakeholders about school uniforms. Data was collected through interviews with stakeholders and also reviewing the documents in TOKI…

  3. A study of combined evaluation of suppliers based on correlation

    Directory of Open Access Journals (Sweden)

    Heting Qiu

    2013-03-01

    Full Text Available Purpose: The Selection of logistics service providers is an important issue in supply chain management. But different evaluation methods may lead to different results, which could cause inconsistent conclusions. This paper makes use of a new perspective to combine with a variety of methods to eliminate the deviation of different single evaluation methods. Design/methodology/approach: This paper expounds the application of the combined evaluation method based on correlation. Entropy method, factor analysis, grey colligation evaluation and AHP have been used for research. Findings: According to the evaluate result, the ranking of suppliers obtained by each method have obvious differences. The result shows that combined evaluation method can eliminate the deviation of different single evaluation methods. Originality/value: The combined evaluation method makes up for the defects of single evaluation methods and obtains a result that is more stable and creditable with smaller deviation. This study can provide the enterprise leaders with more scientific method to select their cooperative companies. 

  4. DETERMINATION OF IMPORTANCE EVALUATION FOR THE SUBSURFACE EXPLORATORY STUDIES FACILITY

    International Nuclear Information System (INIS)

    Clark, W.J.

    1999-01-01

    This Determination of Importance Evaluation (DIE) applies to the Subsurface Exploratory Studies Facility (ESF), encompassing the Topopah Spring (TS) Loop from Station 0+00 meters (m) at the North Portal to breakthrough at the South Portal (approximately 78+77 m), the Enhanced Characterization of the Repository Block (ECRB) East-West Cross Drift Starter Tunnel (to approximate ECRB Station 0+26 m), and ancillary test and operation support areas in the TS Loop. This evaluation applies to the construction, operation, and maintenance of these excavations. A more detailed description of these items is provided in Section 6.0. Testing activities are not evaluated in this DIE. Certain construction activities with respect to testing activities are evaluated; but the testing activities themselves are not evaluated. The DIE for ESF Subsurface Testing Activities (BAJ3000000-01717-2200-000111) (CRWMS M and O 1998a) evaluates Subsurface ESF Testing activities. The construction, operation, and maintenance of the TS Loop niches and alcove slot cuts is evaluated herein and is also discussed in CRWMS M and O 1998a. The construction, operation, and maintenance of the Busted Butte subsurface test area in support of the Unsaturated Zone (UZ) Transport Test is evaluated in CRWMS M and O 1998a. Potential test-to-test interference and the waste isolation impacts of testing activities are evaluated in the ESF Subsurface Testing Activities DIE and other applicable evaluation(s) for the Job Package (JP), Test Planning Package (TPP), and/or Field Work Package (FWP). The objectives of this DIE are to determine whether the Subsurface ESF TS Loop and associated excavations, including activities associated with their construction and operation, potentially impact site characterization testing or the waste isolation capabilities of the site. Controls needed to limit any potential impacts are identified. The validity and veracity of the individual tests, including data collection, are the

  5. DETERMINATION OF IMPORTANCE EVALUATION FOR THE SUBSURFACE EXPORATORY STUDIES FACILITY

    Energy Technology Data Exchange (ETDEWEB)

    W.J. Clark

    1999-06-28

    This Determination of Importance Evaluation (DIE) applies to the Subsurface Exploratory Studies Facility (ESF), encompassing the Topopah Spring (TS) Loop from Station 0+00 meters (m) at the North Portal to breakthrough at the South Portal (approximately 78+77 m), the Enhanced Characterization of the Repository Block (ECRB) East-West Cross Drift Starter Tunnel (to approximate ECRB Station 0+26 m), and ancillary test and operation support areas in the TS Loop. This evaluation applies to the construction, operation, and maintenance of these excavations. A more detailed description of these items is provided in Section 6.0. Testing activities are not evaluated in this DIE. Certain construction activities with respect to testing activities are evaluated; but the testing activities themselves are not evaluated. The DIE for ESF Subsurface Testing Activities (BAJ3000000-01717-2200-00011 Rev 01) (CRWMS M&O 1998a) evaluates Subsurface ESF Testing activities. The construction, operation, and maintenance of the TS Loop niches and alcove slot cuts is evaluated herein and is also discussed in CRWMS M&O 1998a. The construction, operation, and maintenance of the Busted Butte subsurface test area in support of the Unsaturated Zone (UZ) Transport Test is evaluated in CRWMS M&O 1998a. Potential test-to-test interference and the waste isolation impacts of testing activities are evaluated in the ESF Subsurface Testing Activities DIE and other applicable evaluation(s) for the Job Package (JP), Test Planning Package (TPP), and/or Field Work Package (FWP). The objectives of this DIE are to determine whether the Subsurface ESF TS Loop and associated excavations, including activities associated with their construction and operation, potentially impact site characterization testing or the waste isolation capabilities of the site. Controls needed to limit any potential impacts are identified. The validity and veracity of the individual tests, including data collection, are the responsibility

  6. Integration of DAS (distributed acoustic sensing) vertical seismic profile and geostatistically modeled lithology data to characterize an enhanced geothermal system.

    Science.gov (United States)

    Cronin, S. P.; Trainor Guitton, W.; Team, P.; Pare, A.; Jreij, S.; Powers, H.

    2017-12-01

    In March 2016, a 4-week field data acquisition took place at Brady's Natural Lab (BNL), an enhanced geothermal system (EGS) in Fallan, NV. During these 4 weeks, a vibe truck executed 6,633 sweeps, recorded by nodal seismometers, horizontal distributed acoustic sensing (DAS) cable, and 400 meters of vertical DAS cable. DAS provides lower signal to noise ratio than traditional geophones but better spatial resolution. The analysis of DAS VSP included Fourier transform, and filtering to remove all up-going energy. Thus, allowing for accurate first arrival picking. We present an example of the Gradual Deformation Method (GDM) using DAS VSP and lithological data to produce a distribution of valid velocity models of BNL. GDM generates continuous perturbations of prior model realizations seeking the best match to the data (i.e. minimize the misfit). Prior model realizations honoring the lithological data were created using sequential Gaussian simulation, a commonly used noniterative geostatistical method. Unlike least-squares-based methods of inversion, GDM readily incorporates a priori information, such as a variogram calculated from well-based lithology information. Additionally, by producing a distribution of models, as opposed to one optimal model, GDM allows for uncertainty quantification. This project aims at assessing the integrated technologies ability to monitor changes in the water table (possibly to one meter resolution) by exploiting the dependence of seismic wave velocities on water saturation of the subsurface. This project, which was funded in part by the National Science Foundation, is a part of the PoroTomo project, funded by a grant from the U.S. Department of Energy.

  7. Verification of the geostatistical inference code INFERENS, Version 1.1, and demonstration using data from Finnsjoen

    International Nuclear Information System (INIS)

    Geier, J.

    1993-06-01

    This report describes preliminary verification and demonstration of the geostatistical inference code, INFERENS Version 1.1. This code performs regularization of packer test conductivities, and iterative generalized least-squares estimation (IGLSE) of nested covariance models and spatial trends for the regularized data. Cross-validation is used to assess the quality of the estimated models in terms of statistics for the kriging errors. The code includes a capability to generate synthetic datasets for a given configuration of packer tests; this capability can be used for verification exercises and numerical experiments to aid in the design of packer testing programs. The report presents the results of a set of verification test cases. The test cases were designed to test the ability of INFERENS 1.1 to estimate the parameters of a variety of covariance models, with or without trends. This was done using synthetic datasets. This report also describes an application of INFERENS 1.1 to the dataset from the Finnsjoen site. The results are roughly similar to those obtained previously by Norman (1992a) using INFERENS 1.0, for the comparable cases. The actual numerical results are different, which may be due to changes in the fitting algorithms, and differences in how the lag pairs are divided into lag classes. The demonstrations confirm the result previously obtained by Norman, that the fitted horizontally isotropic models are less good, in terms of their cross-validation statistics, than the corresponding isotropic models. The use of nested covariance models is demonstrated to give visually improved fits to the sample semivariograms, at both short and long lag distances. However, despite the good match to the semivariograms, the nested models obtained are not better than the simple models, in terms of cross-validation statistics

  8. Spatial analysis and risk mapping of soil-transmitted helminth infections in Brazil, using Bayesian geostatistical models.

    Science.gov (United States)

    Scholte, Ronaldo G C; Schur, Nadine; Bavia, Maria E; Carvalho, Edgar M; Chammartin, Frédérique; Utzinger, Jürg; Vounatsou, Penelope

    2013-11-01

    Soil-transmitted helminths (Ascaris lumbricoides, Trichuris trichiura and hookworm) negatively impact the health and wellbeing of hundreds of millions of people, particularly in tropical and subtropical countries, including Brazil. Reliable maps of the spatial distribution and estimates of the number of infected people are required for the control and eventual elimination of soil-transmitted helminthiasis. We used advanced Bayesian geostatistical modelling, coupled with geographical information systems and remote sensing to visualize the distribution of the three soil-transmitted helminth species in Brazil. Remotely sensed climatic and environmental data, along with socioeconomic variables from readily available databases were employed as predictors. Our models provided mean prevalence estimates for A. lumbricoides, T. trichiura and hookworm of 15.6%, 10.1% and 2.5%, respectively. By considering infection risk and population numbers at the unit of the municipality, we estimate that 29.7 million Brazilians are infected with A. lumbricoides, 19.2 million with T. trichiura and 4.7 million with hookworm. Our model-based maps identified important risk factors related to the transmission of soiltransmitted helminths and confirm that environmental variables are closely associated with indices of poverty. Our smoothed risk maps, including uncertainty, highlight areas where soil-transmitted helminthiasis control interventions are most urgently required, namely in the North and along most of the coastal areas of Brazil. We believe that our predictive risk maps are useful for disease control managers for prioritising control interventions and for providing a tool for more efficient surveillance-response mechanisms.

  9. ExaGeoStat: A High Performance Unified Framework for Geostatistics on Manycore Systems

    KAUST Repository

    Abdulah, Sameh

    2017-08-09

    We present ExaGeoStat, a high performance framework for geospatial statistics in climate and environment modeling. In contrast to simulation based on partial differential equations derived from first-principles modeling, ExaGeoStat employs a statistical model based on the evaluation of the Gaussian log-likelihood function, which operates on a large dense covariance matrix. Generated by the parametrizable Matern covariance function, the resulting matrix is symmetric and positive definite. The computational tasks involved during the evaluation of the Gaussian log-likelihood function become daunting as the number n of geographical locations grows, as O(n2) storage and O(n3) operations are required. While many approximation methods have been devised from the side of statistical modeling to ameliorate these polynomial complexities, we are interested here in the complementary approach of evaluating the exact algebraic result by exploiting advances in solution algorithms and many-core computer architectures. Using state-of-the-art high performance dense linear algebra libraries associated with various leading edge parallel architectures (Intel KNLs, NVIDIA GPUs, and distributed-memory systems), ExaGeoStat raises the game for statistical applications from climate and environmental science. ExaGeoStat provides a reference evaluation of statistical parameters, with which to assess the validity of the various approaches based on approximation. The framework takes a first step in the merger of large-scale data analytics and extreme computing for geospatial statistical applications, to be followed by additional complexity reducing improvements from the solver side that can be implemented under the same interface. Thus, a single uncompromised statistical model can ultimately be executed in a wide variety of emerging exascale environments.

  10. Sustaining and Improving Study Abroad Experiences Through Comparative Evaluation.

    Science.gov (United States)

    Johanson, Linda S

    Researchers have related participation in study abroad experiences to many positive outcomes for nursing students; however, educators are faced with the task of not only developing meaningful study abroad opportunities but sustaining and improving them as well. Educators can evaluate repeat study abroad programs by comparing experiences, looking for trends, and conjecturing rationales. To illustrate this process, an example of a study abroad opportunity that has been repeated over 11 years is presented. The first six years have been compared to the most recent five years, revealing three categories of change for evaluation and the resulting course improvements.

  11. Spatial distribution of soil organic carbon and total nitrogen based on GIS and geostatistics in a small watershed in a hilly area of northern China.

    Science.gov (United States)

    Peng, Gao; Bing, Wang; Guangpo, Geng; Guangcan, Zhang

    2013-01-01

    The spatial variability of soil organic carbon (SOC) and total nitrogen (STN) levels is important in both global carbon-nitrogen cycle and climate change research. There has been little research on the spatial distribution of SOC and STN at the watershed scale based on geographic information systems (GIS) and geostatistics. Ninety-seven soil samples taken at depths of 0-20 cm were collected during October 2010 and 2011 from the Matiyu small watershed (4.2 km(2)) of a hilly area in Shandong Province, northern China. The impacts of different land use types, elevation, vegetation coverage and other factors on SOC and STN spatial distributions were examined using GIS and a geostatistical method, regression-kriging. The results show that the concentration variations of SOC and STN in the Matiyu small watershed were moderate variation based on the mean, median, minimum and maximum, and the coefficients of variation (CV). Residual values of SOC and STN had moderate spatial autocorrelations, and the Nugget/Sill were 0.2% and 0.1%, respectively. Distribution maps of regression-kriging revealed that both SOC and STN concentrations in the Matiyu watershed decreased from southeast to northwest. This result was similar to the watershed DEM trend and significantly correlated with land use type, elevation and aspect. SOC and STN predictions with the regression-kriging method were more accurate than those obtained using ordinary kriging. This research indicates that geostatistical characteristics of SOC and STN concentrations in the watershed were closely related to both land-use type and spatial topographic structure and that regression-kriging is suitable for investigating the spatial distributions of SOC and STN in the complex topography of the watershed.

  12. Individual performance evaluation of the Brazilian Nuclear Energy Commission (CNEN): a meta-evaluative study

    International Nuclear Information System (INIS)

    Bezerra, Leonardo Ferreira

    2017-01-01

    The present study is a summative meta-evaluation that had as objective to evaluate the quality of the process of evaluation of individual performance of the servers of the National Commission of Nuclear Energy, being guided by the scientific curiosity to know to what extent the evaluation of performance the National Commission for Nuclear Energy meets the quality standards disseminated by the Joint Committee on Standards for Educational Evaluation. The methodology chosen to be used was based on the management approach and had as a guiding principle of the study the elaboration of a framework of criteria considering the aforementioned standards. The criteria established in the criteria framework guided the preparation of the items of the questionnaire sent to the National Commission of Nuclear Energy servers. In addition to the questionnaire, the observation of this author was considered in the context where the phenomenon occurred, which allowed a better reflective analysis of the data collected by the questionnaire. Regarding the results, it can be inferred that the performance evaluation developed at the National Commission of Nuclear Energy can be considered of quality, highlighting the servers' trust for the data, the communication process of the program stages, the credibility of the evaluators, the process of negotiation of goals and adaptability of the instrument over the course of the cycle. However, there are some opportunities for improvement, considering the relevance of evaluation as a tool to improve the performance of the autarchy's servers. Among the points that need to be improved is that there is currently a lack of knowledge about the legal basis and justification of the process of evaluation process by the servers and the lack of clarity regarding the content of the final evaluation report. Among the recommendations of this study, one can consider as the most relevant the need to: disseminate the results of this meta-evaluation to the

  13. Wound assessment tools and nurses’ needs: an evaluation study

    OpenAIRE

    Greatrex-White, Sheila; Moxey, Helen

    2013-01-01

    The purpose of this study was to ascertain how well different wound assessment tools meet the needs of nurses in carrying out general wound assessment and whether current tools are fit for purpose. The methodology employed was evaluation research. In order to conduct the evaluation, a literature review was undertaken to identify the criteria of an optimal wound assessment tool which would meet nurses’ needs. Several freely available wound assessment tools were selected based on predetermin...

  14. Impact Evaluation Study for Institution Strengthening of Social Food Distribution

    Directory of Open Access Journals (Sweden)

    Budiman Notoatmojo

    2016-03-01

    Full Text Available The general objectives of this study were to evaluate whether the implementation of activities for strengthening LDPM could achieve the expected goals, to evaluate whether the LDPM strengthening activities had a positive impact. The study analysis used was descriptive, comparison, and financial analysis. The results of this study have shown that LDPM farmers’ income have increased significantly, and the Gapoktan as LPDM farmers’ institution has been significantly developing as a Bulog function in procuring grain paddy from farmers during peak harvest and distributing rice to stabilize the price of rice during the limited rice in the market.

  15. Evaluating QR Code Case Studies Using a Mobile Learning Framework

    Science.gov (United States)

    Rikala, Jenni

    2014-01-01

    The aim of this study was to evaluate the feasibility of Quick Response (QR) codes and mobile devices in the context of Finnish basic education. The feasibility was analyzed through a mobile learning framework, which includes the core characteristics of mobile learning. The study is part of a larger research where the aim is to develop a…

  16. Evaluation of Emotional Literacy Activities: A Phenomenological Study

    Science.gov (United States)

    Oksuz, Yucel

    2016-01-01

    The present study aims to evaluate impact of the emotional literacy activities through participant student's experiences. Emotional literacy activities, including social-emotional skills Goleman's emotional intelligence and Fapuel's emotional literacy model designed and conducted for 2 months on primary school students, who study in 4th grade. The…

  17. Radiological evaluation of tumor response in oncological studies (tumor response evaluation)

    International Nuclear Information System (INIS)

    Gebauer, B.; Riess, H.

    2011-01-01

    Purpose: Radiological-morphological response evaluation plays a major role in oncological therapy and studies for approval. Specific criteria have been developed for some tumor entities and chemotherapeutics. Application, limitations and definitions of the most frequently used criteria for tumor response evaluation will be presented. Materials and Methods: Review based on a selective literature research. Results: In clinical oncological therapy studies, WHO and RECIST are the most frequently used criteria to evaluate morphological therapy response. RECIST criteria have been modified recently, especially with respect to the evaluation of lymph nodes, and were published as RECIST 1.1 in 2009. All criteria were originally developed and defined to review clinical multicenter trials for approval. Using these criteria in a clinical situation, certain limitations have to be considered. To evaluate response, a baseline scan before therapy start is mandatory. Special tumor response criteria have been defined for some certain tumor entities. Oncologists and radiologists should define in advance which criteria are used before starting therapy. Conclusion: The use of defined criteria is very important in oncology response evaluation. In-depth knowledge of the criteria and their limits is required for correct usage. (orig.)

  18. Study on automatic ECT data evaluation by using neural network

    International Nuclear Information System (INIS)

    Komatsu, H.; Matsumoto, Y.; Badics, Z.; Aoki, K.; Nakayasu, F.; Hashimoto, M.; Miya, K.

    1994-01-01

    At the in--service inspection of the steam generator (SG) tubings in Pressurized Water Reactor (PWR) plant, eddy current testing (ECT) has been widely used at each outage. At present, ECT data evaluation is mainly performed by ECT data analyst, therefore it has the following problems. Only ECT signal configuration on the impedance trajectory is used in the evaluation. It is an enormous time consuming process. The evaluation result is influenced by the ability and experience of the analyst. Especially, it is difficult to identify the true defect signal hidden in background signals such as lift--off noise and deposit signals. In this work, the authors performed the study on the possibility of the application of neural network to ECT data evaluation. It was demonstrated that the neural network proved to be effective to identify the nature of defect, by selecting several optimum input parameters to categorize the raw ECT signals

  19. Methodology and applications in non-linear model-based geostatistics

    DEFF Research Database (Denmark)

    Christensen, Ole Fredslund

    . Conditioned by an underlying and unobserved Gaussian process the observations at the measured locations follow a generalised linear model. Concerning inference Markov chain Monte Carlo methods are used. The study of these models is the main topic of the thesis. Construction of priors, and the use of flat...... priors for Bayesian inference is discussed. Procedures for parameter estimation and prediction are studied. Theoretical properties of Markov chain Monte Carlo algorithms are investigated, and different algorithms are compared. In addition, the thesis contains a manual for an R-package, geoRglmm, which...

  20. Methodology and Applications in Non-linear Model-based Geostatistics

    DEFF Research Database (Denmark)

    Christensen, Ole Fredslund

    that are approximately Gaussian. Parameter estimation and prediction for the transformed Gaussian model is studied. In some cases a transformation cannot possibly render the data Gaussian. A methodology for analysing such data was introduced by Diggle, Tawn and Moyeed (1998): The generalised linear spatial model....... Conditioned by an underlying and unobserved Gaussian process the observations at the measured locations follow a generalised linear model. Concerning inference Markov chain Monte Carlo methods are used. The study of these models is the main topic of the thesis. Construction of priors, and the use of flat...... contains functions for inference in generalised linear spatial models.    ...

  1. Impact of copper sulfate application at an urban Brazilian reservoir: A geostatistical and ecotoxicological approach.

    Science.gov (United States)

    Leal, P R; Moschini-Carlos, V; López-Doval, J C; Cintra, J P; Yamamoto, J K; Bitencourt, M D; Santos, R F; Abreu, G C; Pompêo, M L M

    2018-03-15

    A landscape ecotoxicology approach was used to assess the spatial distribution of copper in the recent bottom sediment (surficial sediment) of a Brazilian subtropical reservoir (the Guarapiranga reservoir) and its potential ecotoxicological impacts on the reservoir ecosystem and the local society. We discuss the policies and procedures that have been employed for the management of this reservoir over the past four decades. Spatial heterogeneity in the reservoir was evaluated by means of sampling design and statistical analysis based on kriging spatial interpolation. The sediment copper concentrations have been converted into qualitative categories in order to interpret the reservoir quality and the impacts of management policies. This conversion followed the Canadian Water Framework Directive (WFD) ecotoxicological concentration levels approach, employing sediment quality guidelines (SQGs). The SQG values were applied as the copper concentration thresholds for quantitative-qualitative conversion of data for the surficial sediment of the Guarapiranga. The SQGs used were as follows: a) interim sediment quality guideline (ISQG), b) probable effect level (PEL), and c) regional reference value (RRV). The quantitative results showed that the spatial distribution of copper in the recent bottom sediment reflected the reservoir's management policy and the copper application protocol, and that the copper concentrations varied considerably, ranging from virtually-zero to in excess of 3g copper /kg ds . The qualitative results demonstrated that the recent bottom sediment was predominantly in a bad or very bad condition, and could therefore have impacts on the local society and the ecosystem. It could be concluded that the management policy for this reservoir was mainly determined by the desire to minimize short-term costs, disregarding long-term socioeconomic and environmental consequences. Copyright © 2017. Published by Elsevier B.V.

  2. Development of Geostatistical Models to Estimate CO2 Storage Resource in Sedimentary Geologic Formations

    Science.gov (United States)

    Popova, Olga H.

    Dental hygiene students must embody effective critical thinking skills in order to provide evidence-based comprehensive patient care. The problem addressed in this study it was not known if and to what extent concept mapping and reflective journaling activities embedded in a curriculum over a 4-week period, impacted the critical thinking skills of 22 first and second-year dental hygiene students attending a community college in the Midwest. The overarching research questions were: what is the effect of concept mapping, and what is the effect of reflective journaling on the level of critical thinking skills of first and second year dental hygiene students? This quantitative study employed a quasi-experimental, pretest-posttest design. Analysis of Covariance (ANCOVA) assessed students' mean scores of critical thinking on the California Critical Thinking Skills Test (CCTST) pretest and posttest for the concept mapping and reflective journaling treatment groups. The results of the study found an increase in CCTST posttest scores with the use of both concept mapping and reflective journaling. However, the increase in scores was not found to be statistically significant. Hence, this study identified concept mapping using Ausubel's assimilation theory and reflective journaling incorporating Johns's revision of Carper's patterns of knowing as potential instructional strategies and theoretical models to enhance undergraduate students' critical thinking skills. More research is required in this area to draw further conclusions. Keywords: Critical thinking, critical thinking development, critical thinking skills, instructional strategies, concept mapping, reflective journaling, dental hygiene, college students.

  3. Integrating interferometric SAR data with levelling measurements of land subsidence using geostatistics

    NARCIS (Netherlands)

    Zhou, Y.; Stein, A.; Molenaar, M.

    2003-01-01

    Differential Synthetic Aperture Radar (SAR) interferometric (D-InSAR) data of ground surface deformation are affected by several error sources associated with image acquisitions and data processing. In this paper, we study the use of D-InSAR for quantifying land subsidence due to groundwater

  4. Field Artillery Ammunition Processing System (FAAPS) concept evaluation study

    Energy Technology Data Exchange (ETDEWEB)

    Kring, C.T.; Babcock, S.M.; Watkin, D.C.; Oliver, R.P.

    1992-06-01

    The Field Artillery Ammunition Processing System (FAAPS) is an initiative to introduce a palletized load system (PLS) that is transportable with an automated ammunition processing and storage system for use on the battlefield. System proponents have targeted a 20% increase in the ammunition processing rate over the current operation while simultaneously reducing the total number of assigned field artillery battalion personnel by 30. The overall objective of the FAAPS Project is the development and demonstration of an improved process to accomplish these goals. The initial phase of the FAAPS Project and the subject of this study is the FAAPS concept evaluation. The concept evaluation consists of (1) identifying assumptions and requirements, (2) documenting the process flow, (3) identifying and evaluating technologies available to accomplish the necessary ammunition processing and storage operations, and (4) presenting alternative concepts with associated costs, processing rates, and manpower requirements for accomplishing the operation. This study provides insight into the achievability of the desired objectives.

  5. A comparison of spatial rainfall estimation techniques: A case study ...

    African Journals Online (AJOL)

    Two geostatistical interpolation techniques (kriging and cokriging) were evaluated against inverse distance weighted (IDW) and global polynomial interpolation (GPI). Of the four spatial interpolators, kriging and cokriging produced results with the least root mean square error (RMSE). A digital elevation model (DEM) was ...

  6. The Evaluation of Study Success between Online Study and Classroom Study Environment

    Directory of Open Access Journals (Sweden)

    Singkhamfu Phudinan

    2016-01-01

    Full Text Available Online study has increasingly become more attractive to students at university level due to convenience access to their instructors and to study resources. This study has developed online social network for study. It proposes to provide lesson content availability, past lecture, by sending online study lesson media to students’ mobile phone or tablet. Approximately 85 undergraduate software engineering students participated for 1.5 semesters. In comparing the use of the study toll, and without the tool, the alterations were found between traditional classroom learning style and online study. Also, the study’s aim was to attest the online study tool’s efficiency. However, these results were not obvious when the achievement factor was controlled by the limitation of time. The primary purpose of this study is to evaluate these two groups of students with extended experiment time for a noticeable result by used questionnaires course examination, and inventory of ILP learning process. The observed, shows that students with online study tools scored higher on course examinations after measures by the mentioned methodology.

  7. Family Assessment in Psychoeducational Evaluations: Case Studies with the Family Adaptability and Cohesion Evaluation Scales.

    Science.gov (United States)

    Gaughan, Edward

    1995-01-01

    Most recent articles on school psychologist involvement with families have been theoretical or conceptual in nature, and little has appeared regarding useful procedures. This article suggests an existing self-report measure that may be a useful addition to psychoeducational evaluations. Four case studies using the technique are presented, its…

  8. A geostatistical methodology for the optimal design of space-time hydraulic head monitoring networks and its application to the Valle de Querétaro aquifer.

    Science.gov (United States)

    Júnez-Ferreira, H E; Herrera, G S

    2013-04-01

    This paper presents a new methodology for the optimal design of space-time hydraulic head monitoring networks and its application to the Valle de Querétaro aquifer in Mexico. The selection of the space-time monitoring points is done using a static Kalman filter combined with a sequential optimization method. The Kalman filter requires as input a space-time covariance matrix, which is derived from a geostatistical analysis. A sequential optimization method that selects the space-time point that minimizes a function of the variance, in each step, is used. We demonstrate the methodology applying it to the redesign of the hydraulic head monitoring network of the Valle de Querétaro aquifer with the objective of selecting from a set of monitoring positions and times, those that minimize the spatiotemporal redundancy. The database for the geostatistical space-time analysis corresponds to information of 273 wells located within the aquifer for the period 1970-2007. A total of 1,435 hydraulic head data were used to construct the experimental space-time variogram. The results show that from the existing monitoring program that consists of 418 space-time monitoring points, only 178 are not redundant. The implied reduction of monitoring costs was possible because the proposed method is successful in propagating information in space and time.

  9. A retrospective study evaluating the efficacy of identification and ...

    African Journals Online (AJOL)

    Full Title: A retrospective study evaluating the efficacy of identification and management of sepsis at a district-level hospital internal medicine department in the Western Cape Province, South Africa, in comparison with the guidelines stipulated in the 2012 Surviving Sepsis Campaign. Background. Currently there is little ...

  10. Sponsorship Evaluation Scale (SES): a validity and reliability study ...

    African Journals Online (AJOL)

    The evaluation of consumer response to sport sponsorship is limited in the academic literature. This research was aimed to conduct a dimensionality, validity and reliability study of the Speed and Thompson Sponsorship Questionnaire in Turkey (2000). Eight hundred and fifty-two (852) university students participated in the ...

  11. Study Design and Data Gathering Guide for Serious Games’ Evaluation

    NARCIS (Netherlands)

    Baalsrud Hauge, Jannicke; Boyle, Elizabeth; Mayer, Igor; Nadolski, Rob; Riedel, Johann C. K. H.; Moreno-Ger, Pablo; Bellotti, Francesco; Lim, Theodore; Ritchie, James

    2013-01-01

    Baalsrud Hauge, J., Boyle, E., Mayer, I., Nadolski, R. J., Riedel, J. C. K. H., Moreno-Ger, P., Bellotti, F., Lim, T., & Ritchie, J. (2013). Study Design and Data Gathering Guide for Serious Games’ Evaluation. In T. M. Connolly, T. Hainey, E. Boyle, G. Baxter, & P. Moreno-Ger (Eds.), Psychology,

  12. Evaluation studies of some medicinal plant extracts and fungicides ...

    African Journals Online (AJOL)

    Evaluation studies of some medicinal plant extracts and fungicides against Alternaria solani. S Phalisteen, S Ishaq, K Amardeep, J Arif, S Sami. Abstract. Alternaria is a polyphagus fungus that occurs frequently on dead and decaying organic material and is responsible for causing leaf spot disease. In Indian subcontinent ...

  13. Ensuring Data Quality in Extension Research and Evaluation Studies

    Science.gov (United States)

    Radhakrishna, Rama; Tobin, Daniel; Brennan, Mark; Thomson, Joan

    2012-01-01

    This article presents a checklist as a guide for Extension professionals to use in research and evaluation studies they carry out. A total of 40 statements grouped under eight data quality components--relevance, objectivity, validity, reliability, integrity, generalizability, completeness, and utility--are identified to ensure that research…

  14. Molecular evaluation of genetic diversity and association studies in ...

    Indian Academy of Sciences (India)

    Molecular evaluation of genetic diversity and association studies in rice. (Oryza sativa L.) C. Vanniarajan, K. K. Vinod and Andy Pereira. J. Genet. 91, 9–19. Table 1. Chromosome-wise distribution of SSR alleles and their number (k), polymorphic information content (PIC) and allele discrimination index (Dm). Chromosome.

  15. Peaceful Uses Bona Fides: Criteria for Evaluation and Case Studies

    Energy Technology Data Exchange (ETDEWEB)

    Ajemian, Chris K.; Hazel, Mike; Kessler, Carol E.; Mathews, Carrie E.; Morris, Fred A.; Seward, Amy M.; Peterson, Danielle J.; Smith, Brian W.

    2007-06-06

    This study applies a set of indicators to assess the peaceful nature of a state’s nuclear program. Evaluation of a country’s nuclear program relative to these indicators can help the international community to take appropriate actions to ensure that the growth of the global nuclear energy industry proceeds peacefully and to minimize nuclear proliferation risks.

  16. Digital Libraries and Repositories in India: An Evaluative Study

    Science.gov (United States)

    Mittal, Rekha; Mahesh, G.

    2008-01-01

    Purpose: The purpose of this research is to identify and evaluate the collections within digital libraries and repositories in India available in the public domain. Design/methodology/approach: The digital libraries and repositories were identified through a study of the literature, as well as internet searching and browsing. The resulting digital…

  17. A Study on the Evaluation of Industrial Solid Waste Management ...

    African Journals Online (AJOL)

    A Study on the Evaluation of Industrial Solid Waste Management. Approaches in Some Industries in Aba, South Eastern Nigeria. Ajero, C.M.U and Chigbo,U.N. Department of Environmental Biology Imo State University, Owerri Imo State Nigeria. medoayero@yahoo.com. Abstract. Industrial solid waste is a serious health ...

  18. Evaluating care from a care ethical perspective:: A pilot study.

    Science.gov (United States)

    Kuis, Esther E; Goossensen, Anne

    2017-08-01

    Care ethical theories provide an excellent opening for evaluation of healthcare practices since searching for (moments of) good care from a moral perspective is central to care ethics. However, a fruitful way to translate care ethical insights into measurable criteria and how to measure these criteria has as yet been unexplored: this study describes one of the first attempts. To investigate whether the emotional touchpoint method is suitable for evaluating care from a care ethical perspective. An adapted version of the emotional touchpoint interview method was used. Touchpoints represent the key moments to the experience of receiving care, where the patient recalls being touched emotionally or cognitively. Participants and research context: Interviews were conducted at three different care settings: a hospital, mental healthcare institution and care facility for older people. A total of 31 participants (29 patients and 2 relatives) took part in the study. Ethical considerations: The research was found not to be subject to the (Dutch) Medical Research Involving Human Subjects Act. A three-step care ethical evaluation model was developed and described using two touchpoints as examples. A focus group meeting showed that the method was considered of great value for partaking institutions in comparison with existing methods. Reflection and discussion: Considering existing methods to evaluate quality of care, the touchpoint method belongs to the category of instruments which evaluate the patient experience. The touchpoint method distinguishes itself because no pre-defined categories are used but the values of patients are followed, which is an essential issue from a care ethical perspective. The method portrays the insider perspective of patients and thereby contributes to humanizing care. The touchpoint method is a valuable instrument for evaluating care; it generates evaluation data about the core care ethical principle of responsiveness.

  19. Simulation studies for the evaluation of health information technologies

    DEFF Research Database (Denmark)

    Ammenwerth, Elske; Hackl, Werner; Binzer, Kristine

    2012-01-01

    is not sufficiently mature. Laboratory-based evaluations have also been shown to have insufficient external validity. Simulation studies seem to be a way to bridge this gap. The aim of this study was to evaluate, using a simulation methodology, the impact of a new prototype of an electronic medication management...... system on the appropriateness of prescriptions and drugrelated activities, including laboratory test ordering or medication changes. This article presents the results of a controlled simulation study with 50 simulation runs, including ten doctors and five simulation patients, and discusses experiences...... and lessons learnt while conducting the study. Although the new electronic medication management system showed tendencies to improve medication safety when compared with the standard system, this tendency was not significant. Altogether, five distinct situations were identified where the new medication...

  20. Using Geoscience and Geostatistics to Optimize Groundwater Monitoring Networks at the Savannah River Site

    International Nuclear Information System (INIS)

    Tuckfield, R.C.

    2001-01-01

    A team of scientists, engineers, and statisticians was assembled to review the operation efficiency of groundwater monitoring networks at US Department of Energy Savannah River Site (SRS). Subsequent to a feasibility study, this team selected and conducted an analysis of the A/M area groundwater monitoring well network. The purpose was to optimize the number of groundwater wells requisite for monitoring the plumes of the principal constituent of concern, viz., trichloroethylene (TCE). The project gathered technical expertise from the Savannah River Technology Center (SRTC), the Environmental Restoration Division (ERD), and the Environmental Protection Department (EPD) of SRS

  1. Determination of reliability of express forecasting evaluation of radiometric enriching ability of non-ferrous ores

    International Nuclear Information System (INIS)

    Kirpishchikov, S.P.

    1991-01-01

    Use of the data of nuclear physical methods of sampling and logging enables to improve reliability of evaluation of radiometric enriching ability of ores, as well as to evaluate quantitatively this reliability. This problem may be solved by using some concepts of geostatistics. The presented results enable to conclude, that the data of nuclear-physical methods of sampling and logging can provide high reliability of evaluation of radiometric enriching ability of non-ferrous ores and their geometrization by technological types

  2. Using multivariate geostatistical methods and geographical clustering to delineate homogeneous winegrowing zones

    Science.gov (United States)

    Moral, Francisco J.; Rebollo, Francisco J.; Paniagua, Luis L.; García, Abelardo

    2014-05-01

    Characterization of homogeneous zones is difficult because of the complex combination of factors which could affect it. In winegrowing regions, zoning studies not only define areas according to their potential to produce specific wines but also identify the key drivers behind their variability and optimize vineyard management for sustainable viticulture. With the aim of characterizing the spatial variability of the main vine-related environmental variables and using this information to determine different zones, climate and topographical data were obtained in Extremadura (southwestern Spain), an important wine region. Thus, accurate maps of all climate indices were produced by using regression-kriging as the most suitable algorithm in which exhaustive secondary information on elevation was incorporated. Maps of topography-derived variables were obtained using GIS tools. Later, principal component analysis and multivariate geographic classification were carried out to define areas of similar characteristics, resulting in three zones. This territory zonification constitutes a basic tool for rational region management, demarcation of production areas, studying new cultivar suitability and its interaction with environment, and it can be the basis for viticultural zoning at larger scales. Finally, the suitability of the territory belonging to the Ribera del Guadiana Denomination of Origin for viticulture was analyzed

  3. Geostatistical analysis of the relationship between airborne electromagnetic data and borehole lithological data

    DEFF Research Database (Denmark)

    Barfod, Adrian; Møller, Ingelise; Christiansen, Anders Vest

    2015-01-01

    We present a large-scale study of the relationship between dense airborne SkyTEM resistivity data and sparse lithological borehole data. Airborne electromagnetic (AEM) data contains information about subsurface geology and hydrologic properties; however extracting this information is not trivial....... surface. By applying the proposed algorithm to all available airborne electromagnetic data, detailed maps of the large-scale resistivity-lihology structures on a National scale in Denmark are constructed....... properties and lithology, and apply this to get a better understanding of large-scale petrophysical structures of the subsurface. The data sampling is carried out in a scheme where data is interpolated onto the position of the boreholes. This allows for a lithological categorization of the interpolated......We present a large-scale study of the relationship between dense airborne SkyTEM resistivity data and sparse lithological borehole data. Airborne electromagnetic (AEM) data contains information about subsurface geology and hydrologic properties; however extracting this information is not trivial...

  4. Elliptic Cylinder Airborne Sampling and Geostatistical Mass Balance Approach for Quantifying Local Greenhouse Gas Emissions.

    Science.gov (United States)

    Tadić, Jovan M; Michalak, Anna M; Iraci, Laura; Ilić, Velibor; Biraud, Sébastien C; Feldman, Daniel R; Bui, Thaopaul; Johnson, Matthew S; Loewenstein, Max; Jeong, Seongeun; Fischer, Marc L; Yates, Emma L; Ryoo, Ju-Mee

    2017-09-05

    In this study, we explore observational, experimental, methodological, and practical aspects of the flux quantification of greenhouse gases from local point sources by using in situ airborne observations, and suggest a series of conceptual changes to improve flux estimates. We address the major sources of uncertainty reported in previous studies by modifying (1) the shape of the typical flight path, (2) the modeling of covariance and anisotropy, and (3) the type of interpolation tools used. We show that a cylindrical flight profile offers considerable advantages compared to traditional profiles collected as curtains, although this new approach brings with it the need for a more comprehensive subsequent analysis. The proposed flight pattern design does not require prior knowledge of wind direction and allows for the derivation of an ad hoc empirical correction factor to partially alleviate errors resulting from interpolation and measurement inaccuracies. The modified approach is applied to a use-case for quantifying CH 4 emission from an oil field south of San Ardo, CA, and compared to a bottom-up CH 4 emission estimate.

  5. Characterization and evaluation studies on some JAERI dosimetry systems

    International Nuclear Information System (INIS)

    Kojima, T.; Sunaga, H.; Tachibana, H.; Takizawa, H.; Tanaka, R.

    2000-01-01

    Characterization and evaluation studies were carried out on some JAERI dosimetry systems, mainly alanine-ESR, in terms of the influence on the dose response of parameters such as orientation at ESR analysis, and the temperature during irradiation and analysis. Feasibility study for application of these dosimetry systems to electrons with energies lower than 4 MeV and bremsstrahlung (X rays) was also performed parallel to their reliability check through international dose intercomparison. (author)

  6. Geostatistical analyses of communication routes in a geo-strategic and regional development perspective

    Directory of Open Access Journals (Sweden)

    Alexandru-Ionuţ Petrişor

    2017-12-01

    Full Text Available Accessibility is a key concept in regional development, with numerous ties to territorial cohesion and polycentricity. Moreover, it also exhibits a geo-strategic function, anchored in the international relationships between countries and continents. The article reviews several case studies, placing analyses of the Romanian accessibility in a broader context. The results show that regional development, overall EU connectivity and possible transit fluxes are prevented by the configuration or lack of communication routes. Increasing the accessibility of regions must be a priority of governments, regardless of political opinions. It is expected that the transition of economy to post-carbon era or other models – green economy, knowledge-based economy etc. – to result into the emergence of new poles and axes of development, and ensure transport sustainability.

  7. Geostatistical simulation of geological architecture and uncertainty propagation in groundwater modeling

    DEFF Research Database (Denmark)

    He, Xiulan

    be compensated by model parameters, e.g. when hydraulic heads are considered. However, geological structure is the primary source of uncertainty with respect to simulations of groundwater age and capture zone. Operational MPS based software has been on stage for just around ten years; yet, issues regarding...... parameters and model structures, which are the primary focuses of this PhD research. Parameter uncertainty was analyzed using an optimization tool (PEST: Parameter ESTimation) in combination with a random sampling method (LHS: Latin Hypercube Sampling). Model structure, namely geological architecture...... geological structures of these three sites provided appropriate conditions for testing the methods. Our study documented that MPS is an efficient approach for simulating geological heterogeneity, especially for non-stationary system. The high resolution of geophysical data such as SkyTEM is valuable both...

  8. Solving inverse problems through a smooth formulation of multiple-point geostatistics

    DEFF Research Database (Denmark)

    Melnikova, Yulia

    In oil and gas sector accurate reservoir description play a crucial role in problems associated with recovery of hydrocarbons, risk estimation and predicting reservoir performance. Knowledge on reservoir properties can be inferred from measurements typically made at the surface by solving...... be inferred, for instance, from a conceptual geological model termed a training image.The main motivation for this study was the challenge posed by history matching, an inverse problem aimed at estimating rock properties from production data. We addressed two main difficulties of the history matching problem...... have proposed a smooth formulation of training-image based priors, which was inspired by the Frequency Matching method developed by our group earlier. The proposed smooth generalization, that integrates data and multiple-point statistics in a probabilistic framework, allows us to find solution by use...

  9. Heavy metals relationship in arable and greenhouse soils of SE Spain using a geostatistical analysis

    Science.gov (United States)

    Gil, Carlos; Joaquin Ramos-Miras, Jose; Rodríguez Martín, Jose Antonio; Boluda, Rafael; Roca, Núria; Bech, Jaume

    2013-04-01

    This study compares heavy metals contents and the main edaphic parameters in greenhouse soils from the W Almería region one of the most productive agricultural systems in Europe, with agricultural soils (arable soils) in western Andalusia, SW Spain. Heavy metals input in agricultural soils mainly occur through pesticides and phytosanitary control products. The hazardousness of the studied elements (Cr, Ni, Pb, Cu, Zn and Cd) is particularly relevant in soils used for intensive greenhouse farming where such agricultural practices, which centre on maximising production, end up with products that finally enter the human food chain directly. Here we explore a total of 199 greenhouse soils and 142 arable soils, representing two scales of variation in this Mediterranean area. Despite their similar edaphic characteristics, the main differences between arable soils and greenhouse soils lie in nutrients contents (P and K) and in certain heavy metals (Cd, Pb and Zn), which reflect widespread use of pesticides in greenhouse farming. One of the most toxic metals is Cd given its mobility, whose concentrations triple in greenhouse soils, although it does not exceed the limits set by Spanish legislation. We conclude that despite anthropic heavy metals input, the association patterns of these elements were similar on the two spatial variability scales. Cd, Pb and Zn contents, and partly those of Cu, are related with agricultural practices. On the short spatial scale, grouping these heavy metals shows very high contents in greenhouse soils in the central northern area of the W Almería region. On the other hand, the associations of Cr and Ni suggest a lithogenic influence combined with a pedogenic effect on spatial maps. This natural origin input becomes more marked on the long spatial scale (arable soils) where the main Cr and Ni contents are found in the vicinity of the Gádor Mountain Range.

  10. Non-destructive evaluation studies for cultural heritage

    International Nuclear Information System (INIS)

    Jayakumar, T.; Babu Rao, C.; Kumar, Anish; Rajkumar, K.V.; Sharma, G.K.; Raj, Baldev

    2009-01-01

    The results of the nondestructive evaluation studies carried out on the Delhi iron pillar and the musical pillars of the Vithala temple at Hampi, Karnataka are discussed. While studies on Delhi iron pillar were carried out with a primary aim to understand the methodology of fabrication of this pillar, the studies on the musical pillars were carried out to finger print/petroligically characterize the stones used in the construction of the musical pillars and to understand the origin of various sounds generated on tapping of the musical pillars by carrying out various acoustic studies. (author)

  11. Grid-Mapping of Hellas Planitia, Mars - Geostatistical Analyses of Cold-Climate Landforms

    Science.gov (United States)

    Voelker, Martin; Hauber, Ernst; Jaumann, Ralf

    2016-10-01

    Hellas Planitia is one of the largest impact basins on Mars, with a diameter of 2,300 km and located in the southern mid-latitudes. The basin also contains the topographically lowest parts of the planet, making it of special interest for water and ice-related geomorphological activities. We applied a Grid-Mapping method to analyze the geographical distribution of possibly ice-related landforms (e.g., latitude-dependent mantle [LDM] and scalloped terrain) in a visual and statistical manner. Thus, we are able to look for yet unrecognized correlations between the landforms themselves and external parameters such as elevation, slope inclination, slope aspect (azimuth), and thermal inertia.By using this method, the study area is separated into 20,100 grids, each 20×20 km. Mapping is based on CTX images at a scale of 1:30,000 in a GIS environment. Because of the huge size of the study area, only every second grid has been mapped. For 21 different landforms, we attributed one of the five following classes to each grid: "dominant", "present", "possible", "absent", and "no data". The non-mapped grids were interpolated later. Statistical calculations have only considered "dominant" and "present" values for reliable results. In normalized distribution diagrams only bins with more than 30 samples are shown.Despite LDM covers Hellas almost entirely, our map shows an elliptical 800×200 km gap in NE Hellas. We suggest this lack of LDM may be the result of the dominant wind circulation pattern within the basin. According to global climate models, cold south-polar wind currents enter Hellas at a breach in its SW rim and rotate clockwise in Hellas. When they reach the northern parts of the Hellas floor around 30°S they warm up, and begin to move south again, subliming or preventing the evolution of LDM in the NE portions of Hellas because of the higher air temperature. In contrast to LDM, scalloped terrain occurs on higher inclined slopes between 6° to 9°. As they are

  12. A study on the quantitative evaluation of skin barrier function

    Science.gov (United States)

    Maruyama, Tomomi; Kabetani, Yasuhiro; Kido, Michiko; Yamada, Kenji; Oikaze, Hirotoshi; Takechi, Yohei; Furuta, Tomotaka; Ishii, Shoichi; Katayama, Haruna; Jeong, Hieyong; Ohno, Yuko

    2015-03-01

    We propose a quantitative evaluation method of skin barrier function using Optical Coherence Microscopy system (OCM system) with coherency of near-infrared light. There are a lot of skin problems such as itching, irritation and so on. It has been recognized skin problems are caused by impairment of skin barrier function, which prevents damage from various external stimuli and loss of water. To evaluate skin barrier function, it is a common strategy that they observe skin surface and ask patients about their skin condition. The methods are subjective judgements and they are influenced by difference of experience of persons. Furthermore, microscopy has been used to observe inner structure of the skin in detail, and in vitro measurements like microscopy requires tissue sampling. On the other hand, it is necessary to assess objectively skin barrier function by quantitative evaluation method. In addition, non-invasive and nondestructive measuring method and examination changes over time are needed. Therefore, in vivo measurements are crucial for evaluating skin barrier function. In this study, we evaluate changes of stratum corneum structure which is important for evaluating skin barrier function by comparing water-penetrated skin with normal skin using a system with coherency of near-infrared light. Proposed method can obtain in vivo 3D images of inner structure of body tissue, which is non-invasive and non-destructive measuring method. We formulate changes of skin ultrastructure after water penetration. Finally, we evaluate the limit of performance of the OCM system in this work in order to discuss how to improve the OCM system.

  13. 3D geostatistical modelling for identifying sinkhole disaster potential zones around the Verkhnekamskoye potash deposit (Russia)

    Science.gov (United States)

    Royer, J. J.; Litaudon, J.; Filippov, L. O.; Lyubimova, T.; Maximovich, N.

    2017-07-01

    This work results from a cooperative scientific program between the Perm State University (Russia) and the University of Lorraine (France). Its objectives are to integrate modern 3D geomodeling in order to improve sustainable mining extraction, especially for predicting and avoiding the formation of sinkholes disaster potential zones. Systematic exploration drill holes performed in the Verkhnekamskoye potash deposit (Perm region, Russia) have been used to build a comprehensive 3D model for better understanding the spatial repartition of the ore quality (geometallurgy). A precise modelling of the mineralized layers allows an estimation of the in-situ ore reserves after interpolating by kriging the potassium (K) and magnesium (Mg) contents at the node of a regular centred grid (over a million cells). Total resources in potassium vary according to the cut-off between 4.7Gt @ 16.1 % K2O; 0.32 % MgCl2 for a cut-off grade at 13.1% K2O and 2.06 Gt @ 18.2 % K2O; 0.32 % MgCl2 at a cut-off of 16.5% K2O. Most of reserves are located in the KPI, KPII and KPIII layers, the KPI being the richest, and KPIII the largest in terms of tonnage. A systematic study of the curvature calculated along the roof of the mineralized layers points out the location of potential main faults which play a major role in the formation of sinkhole during exploitation. A risk map is then derived from this attribute.

  14. Study on categorization of the safety design evaluation event

    Energy Technology Data Exchange (ETDEWEB)

    Kurisaka, Kenichi; Kani, Yoshio [Power Reactor and Nuclear Fuel Development Corp., Oarai, Ibaraki (Japan). Oarai Engineering Center

    1997-05-01

    In order to make a FBR practicable, it is important to make rational categorization of a safety design evaluation event. In this study, for the purpose of providing useful information into the event categorization, we developed the occurrence frequency data of various abnormal events, presented a proposal of the event categorization primarily based on the occurrence frequency and examined efficiency of the proposal. We researched and analyzed abnormal event instances of foreign and domestic FBR plants and of domestic light water reactor power plants. On the basis of the analysis, the failure occurrence frequency of the protection system (PS) in the FBR model plants with electric power production of 600MW and 1,000MW was quantified. Making use of results of probabilistic safety assessment study, loss-of-function probability of the mitigation system (MS) was quantified. Some of combinations of PS failure and loss of MS function were selected and their occurrence frequencies were quantified. We examined problems in the current categorization of the safety design evaluation event and presented a new proposal of the event categorization. Merits of the new proposal are to have divided the current category of `accident` into `small accident` and `rare accident`, explicitly to treat a multiple failure event not as a collateral analysis condition of supposing `a single failure` but as an event to be evaluated, and to have added a category for the event which is beyond design base, but should be supposed to evaluate depth of the safety design in terms of defense-in-depth. Some candidates of the safety design evaluation event were identified and applied to the new proposal. In comparison with the current categorization, we obtained perspective that it was possible to evaluate the safety design more in detail and effectively, especially depth of the safety design such as backup reactor shutdown system, decay heat removal function in a natural circulation mode etc. (J.P.N.)

  15. Application of Learning Curves for Didactic Model Evaluation: Case Studies

    Directory of Open Access Journals (Sweden)

    Felix Mödritscher

    2013-01-01

    Full Text Available The success of (online courses depends, among other factors, on the underlying didactical models which have always been evaluated with qualitative and quantitative research methods. Several new evaluation techniques have been developed and established in the last years. One of them is ‘learning curves’, which aim at measuring error rates of users when they interact with adaptive educational systems, thereby enabling the underlying models to be evaluated and improved. In this paper, we report how we have applied this new method to two case studies to show that learning curves are useful to evaluate didactical models and their implementation in educational platforms. Results show that the error rates follow a power law distribution with each additional attempt if the didactical model of an instructional unit is valid. Furthermore, the initial error rate, the slope of the curve and the goodness of fit of the curve are valid indicators for the difficulty level of a course and the quality of its didactical model. As a conclusion, the idea of applying learning curves for evaluating didactical model on the basis of usage data is considered to be valuable for supporting teachers and learning content providers in improving their online courses.

  16. Geostatistical approach for identifying scale-specific correlations between soil thickness and topographic attributes

    Science.gov (United States)

    Bourennane, Hocine; Salvador-Blanes, Sébastien; Couturier, Alain; Chartin, Caroline; Pasquier, Catherine; Hinschberger, Florent; Macaire, Jean-Jacques; Daroussin, Joël

    2014-09-01

    This paper investigates how the spatial correlations between topographic attributes and a soil thickness can be improved by focusing on the relationships between them at specific spatial scales. In addition, this paper examines the effects of the topographic attribute data sources that are used as explanatory variables for modeling the response variable, and considers the possibility of model extrapolation for mapping beyond the area where the model was established. Here, factorial kriging analysis (FKA) and partial least square regression (PLSR) analysis are used to separate nuggets and small- and large-scale structures in data including four topographic attributes and soil thickness (ST). These analyses were conducted at different scales to analyze the relationships between ST and the selected topographic attributes in the southwest region of the Parisian Basin. The structural correlation coefficients from the FKA show strong correlations between the variables. These correlations, which change as a function of spatial scale, are not revealed by the linear correlation coefficients. The Eigen vectors from the principal component analysis that was performed on the small-scale and large-scale structures of the linear co-regionalization model are used to obtain ST and the topographic attributes at both spatial scales over the study area. The ST models are built as a function of topographic attributes using PLSR. Results have shown that the models built using variables that were assessed at a specific scale are better at predicting the target variable than models that were built using raw data. Regarding the models that were built using raw data, the structural correlations that occur at different spatial scales are merged together and the variance-covariance matrix of the nugget that represents data noise is not filtered out. Measures of model performance that are based on a validation data set have shown that the model based on small-scale structure (Model-S) is

  17. Geostatistical mapping of leakance in a regional aquitard, Oak Ridges Moraine area, Ontario, Canada

    Science.gov (United States)

    Desbarats, A. J.; Hinton, M. J.; Logan, C. E.; Sharpe, D. R.

    2001-01-01

    The Newmarket Till forms a regionally extensive aquitard separating two major aquifer systems in the Greater Toronto area, Canada. The till is incised, and sometimes eroded entirely, by a network of sand- and gravel-filled channels forming productive aquifers and, locally, high-conductivity windows between aquifer systems. Leakage through the till may also be substantial in places. This study investigates the spatial variability of aquitard leakance in order to assess the relative importance of recharge processes to the lower aquifers. With a large database derived from water-well records and containing both hard and soft information, the Sequential Indicator Simulation method is used to generate maps of aquitard thickness and window probability. These can be used for targeting channel aquifers and for identifying potential areas of recharge to the lower aquifers. Conductivities are modeled from sparse data assuming that their correlation range is much smaller than the grid spacing. Block-scale leakances are obtained by upscaling nodal values based on simulated conductivity and thickness fields. Under the "aquifer-flow'' assumption, upscaling is performed by arithmetic spatial averaging. Histograms and maps of upscaled leakances show that heterogeneities associated with aquitard windows have the largest effect on regional groundwater flow patterns. Résumé. La moraine glaciaire de Newmarket constitue un imperméable d'extension régionale séparant deux systèmes aquifères dans la région du Grand Toronto (Canada). La moraine est entaillée, et parfois entièrement érodée, par un réseau de chenaux comblés de sables et de graviers formant des aquifères productifs et, localement, des «fenêtres», zones à forte conductivité hydraulique reliant les systèmes aquifères. Une drainance au travers de la moraine peut également être significative par endroits. Cette étude s'intéresse à la variabilité spatiale de la drainance au travers de l

  18. Evaluation of hybrid power system alternatives: a case study

    International Nuclear Information System (INIS)

    Rosenthal, Andrew L.

    1999-01-01

    Pursuant to executive and statutory policies, the National Park Service (NPS) has been evaluating the use of photovoltaic (PV) hybrid power systems, for many of its remote, off-grid areas. This paper reports the results of a detailed technical and economic evaluation for one such area: the Needles District of Canyonlands National Park. The study evaluates the presented power systems and five alternative power generation configurations, four of which utilise PV. Projections are provided for the generator run-time and fuel use associated with each configuration as well as all initial and future costs. Included in the study are specific recommendations for energy efficiency improvements at the site. Results show that the generation systems presently in use, two full-time diesel generators, has the lowest conventional 20-year life cycle costs (LCC) of the six systems evaluated. However, when emissions costs are included (per NPS guidelines), several of the PV hybrid alternatives attain a lower LCC than the diesel-only systems. General discussion of the effects of initial versus future costs of PV hybrids as they compare with engine generator system is presented. (Author)

  19. Economic evaluation of the Blanket Comparison and Selection Study

    International Nuclear Information System (INIS)

    Waganer, L.M.

    1985-01-01

    The economic impact of employing the highly ranked blankets in the Blanket Comparison and Selection Study (BCSS) was evaluated in the context of both a tokamak and a tandem mirror power reactor (TMR). The economic evaluation criterion was determined to be the cost of electricity. The influencing factors that were considered are the direct cost of the blankets and related systems; the annual cost of blanket replacement; and the performance of the blanket, heat transfer, and energy conversion systems. The technical and cost bases for comparison were those of the STARFIRE and Mirror Advanced Reactor Study conceptual design power plants. The economic evaluation results indicated that the nitrate-salt-cooled blanket concept is an economically attractive concept for either reactor type. The water-cooled, solid breeder blanket is attractive for the tokamak and somewhat less attractive for the TMR. The helium-cooled, liquidlithium breeder blanket is the least economically desirable of higher ranked concepts. The remaining self-cooled liquid-metal and the helium-cooled blanket concepts represent moderately attractive concepts from an economic standpoint. These results are not in concert with those found in the other BCSS evaluation areas (engineering feasibility, safety, and research and development (R and D) requirements). The blankets faring well economically had generally lower cost components, lower pumping power requirements, and good power production capability. On the other hand, helium- and lithium-cooled systems were preferred from the standpoints of safety, engineering feasibility, and R and D requirements

  20. Data envelopment analysis in service quality evaluation: an empirical study

    Science.gov (United States)

    Najafi, Seyedvahid; Saati, Saber; Tavana, Madjid

    2015-09-01

    Service quality is often conceptualized as the comparison between service expectations and the actual performance perceptions. It enhances customer satisfaction, decreases customer defection, and promotes customer loyalty. Substantial literature has examined the concept of service quality, its dimensions, and measurement methods. We introduce the perceived service quality index (PSQI) as a single measure for evaluating the multiple-item service quality construct based on the SERVQUAL model. A slack-based measure (SBM) of efficiency with constant inputs is used to calculate the PSQI. In addition, a non-linear programming model based on the SBM is proposed to delineate an improvement guideline and improve service quality. An empirical study is conducted to assess the applicability of the method proposed in this study. A large number of studies have used DEA as a benchmarking tool to measure service quality. These models do not propose a coherent performance evaluation construct and consequently fail to deliver improvement guidelines for improving service quality. The DEA models proposed in this study are designed to evaluate and improve service quality within a comprehensive framework and without any dependency on external data.

  1. Nuclear plant power up-rate study: feedwater heater evaluations

    International Nuclear Information System (INIS)

    Svensson, Eric; Catapano, Michael; Coakley, Michael; Thomas, Dan

    2014-01-01

    Given today's nuclear industry business climate, it has become common for Utility companies to consider increasing unit capacities through turbine replacement and power up-rates. An integral part of the studies conducted by many towards this end, involve the generation of a set of turbine cycle heat balances with predicted performance parameters for the up-rated condition. Once these tentative operating values are established, it becomes necessary to evaluate the suitability of the existing components within each system to ensure they are capable of continued safe and reliable operation. The ultimate cost for the up-rate, including the cost for any major required modifications or significant replacements is weighed against increased revenue generated from the up-rate over time. Exelon's Peach Bottom Atomic Power Station (PBAPS) is currently planning for an Extended Power up-rate (EPU) for both units. To ensure the existing Feedwater Heaters (FWH) could maintain the operating and transient response margins at the EPU condition, an engineering study was conducted. Powerfect Inc. in conjunction with SPX Heat Transfer LLC were contracted to provide engineering services to analyze the design, thermal performance, reliability and operating conditions at projected EPU conditions. Specifically, to address the following with regard to the station's Feedwater Heaters (FWHs): 1. Evaluate Drain Cooler (DC) Velocities - including zone inlet velocity, cross and window velocities and outlet velocities. 2. Evaluate Drain Cooler Zone Pressure Drop for effect on drain cooler margins to flashing. 3. Evaluate differential pressure allowable across the pass partition plate. 4. Evaluate Drain Cooler Tube Vibration Potential. 5. Perform detailed steam dome velocity calculations. The goal of the study was to identify the most susceptible areas within the heaters for problems and potential failures when operating at the higher duty of the EPU condition for the remaining life

  2. Participant evaluation results for two indoor air quality studies

    International Nuclear Information System (INIS)

    Hawthorne, A.R.; Dudney, C.S.; Cohen, M.A.; Spengler, J.D.

    1987-01-01

    After two surveys for indoor air pollutants (radon and other chemicals) the homeowners were surveyed for their reactions. The results of these participant evaluation surveys, assuming that the participants that responded to the survey were representative, indicate that homeowners will accept a significant level of monitoring activity as part of an indoor air quality field study. Those participants completing surveys overwhelmingly enjoyed being in the studies and would do it again. We believe that the emphasis placed on positive homeowner interactions and efforts made to inform participants throughout our studies were positive factors in this result. There was no substantial differences noted in the responses between the 70-house study, which included a homeowner compensation payment of $100, and the 300-house study, which did not include a compensation payment. These results provide encouragement to conduct future complex, multipollutant indoor air quality studies when they are scientifically sound and cost effective

  3. Status of fusion reactor blanket evaluation studies in France

    International Nuclear Information System (INIS)

    Carre, F.; Chevereau, G.; Gervaise, F.; Proust, E.

    1985-03-01

    In the frame of recent CEA studies aiming at the evaluation and at the comparison of various candidate blanket concepts in moderate power conditions (Psub(n) approximately 2 MW/m 2 ), the present work examines the neutronic and thermomechanical performances of a water cooled Li 17 Pb 83 tubular blanket and those of a helium cooled canister blanket taking advantage of the excellent breeding capability of composite Beryllium/LiAlO 2 (85/15%) breeder elements. The purpose of the following discussion is to justify the impetus for these reference concepts and to summarize the state of their evaluation studies updated by the continuous assimilation of calculations and experiments in progress

  4. Geostatistics for Large Datasets

    KAUST Repository

    Sun, Ying

    2011-10-31

    Each chapter should be preceded by an abstract (10–15 lines long) that summarizes the content. The abstract will appear onlineat www.SpringerLink.com and be available with unrestricted access. This allows unregistered users to read the abstract as a teaser for the complete chapter. As a general rule the abstracts will not appear in the printed version of your book unless it is the style of your particular book or that of the series to which your book belongs. Please use the ’starred’ version of the new Springer abstractcommand for typesetting the text of the online abstracts (cf. source file of this chapter template abstract) and include them with the source files of your manuscript. Use the plain abstractcommand if the abstract is also to appear in the printed version of the book.

  5. High performance APCS conceptual design and evaluation scoping study

    International Nuclear Information System (INIS)

    Soelberg, N.; Liekhus, K.; Chambers, A.; Anderson, G.

    1998-02-01

    This Air Pollution Control System (APCS) Conceptual Design and Evaluation study was conducted to evaluate a high-performance (APC) system for minimizing air emissions from mixed waste thermal treatment systems. Seven variations of high-performance APCS designs were conceptualized using several design objectives. One of the system designs was selected for detailed process simulation using ASPEN PLUS to determine material and energy balances and evaluate performance. Installed system capital costs were also estimated. Sensitivity studies were conducted to evaluate the incremental cost and benefit of added carbon adsorber beds for mercury control, specific catalytic reduction for NO x control, and offgas retention tanks for holding the offgas until sample analysis is conducted to verify that the offgas meets emission limits. Results show that the high-performance dry-wet APCS can easily meet all expected emission limits except for possibly mercury. The capability to achieve high levels of mercury control (potentially necessary for thermally treating some DOE mixed streams) could not be validated using current performance data for mercury control technologies. The engineering approach and ASPEN PLUS modeling tool developed and used in this study identified APC equipment and system performance, size, cost, and other issues that are not yet resolved. These issues need to be addressed in feasibility studies and conceptual designs for new facilities or for determining how to modify existing facilities to meet expected emission limits. The ASPEN PLUS process simulation with current and refined input assumptions and calculations can be used to provide system performance information for decision-making, identifying best options, estimating costs, reducing the potential for emission violations, providing information needed for waste flow analysis, incorporating new APCS technologies in existing designs, or performing facility design and permitting activities

  6. Evaluation of dermatologic emergeny patients: An unicentral prospective clinical study

    OpenAIRE

    Adem Köşlü; İlknur Kıvanç Altunay; Hilal Kaya Erdoğan

    2009-01-01

    Background and Design: The definition of emergent diseases includes potentially risky diseases that need urgent medical intervention. Diagnostic and therapeutic processes are managed mostly at ourpatient setting in dermatology. Therefore, it is unclear that which diseases are real emergencies and which patients apply urgently. There are a few studies assessing this topic. Our aim was to evaluate patients referred to our clinic urgently, and to review the concept of ‘‘real dermatologic emergen...

  7. High performance APCS conceptual design and evaluation scoping study

    Energy Technology Data Exchange (ETDEWEB)

    Soelberg, N.; Liekhus, K.; Chambers, A.; Anderson, G.

    1998-02-01

    This Air Pollution Control System (APCS) Conceptual Design and Evaluation study was conducted to evaluate a high-performance (APC) system for minimizing air emissions from mixed waste thermal treatment systems. Seven variations of high-performance APCS designs were conceptualized using several design objectives. One of the system designs was selected for detailed process simulation using ASPEN PLUS to determine material and energy balances and evaluate performance. Installed system capital costs were also estimated. Sensitivity studies were conducted to evaluate the incremental cost and benefit of added carbon adsorber beds for mercury control, specific catalytic reduction for NO{sub x} control, and offgas retention tanks for holding the offgas until sample analysis is conducted to verify that the offgas meets emission limits. Results show that the high-performance dry-wet APCS can easily meet all expected emission limits except for possibly mercury. The capability to achieve high levels of mercury control (potentially necessary for thermally treating some DOE mixed streams) could not be validated using current performance data for mercury control technologies. The engineering approach and ASPEN PLUS modeling tool developed and used in this study identified APC equipment and system performance, size, cost, and other issues that are not yet resolved. These issues need to be addressed in feasibility studies and conceptual designs for new facilities or for determining how to modify existing facilities to meet expected emission limits. The ASPEN PLUS process simulation with current and refined input assumptions and calculations can be used to provide system performance information for decision-making, identifying best options, estimating costs, reducing the potential for emission violations, providing information needed for waste flow analysis, incorporating new APCS technologies in existing designs, or performing facility design and permitting activities.

  8. Ethics reflection groups in community health services: an evaluation study.

    Science.gov (United States)

    Lillemoen, Lillian; Pedersen, Reidar

    2015-04-17

    Systematic ethics support in community health services in Norway is in the initial phase. There are few evaluation studies about the significance of ethics reflection on care. The aim of this study was to evaluate systematic ethics reflection in groups in community health (including nursing homes and residency), - from the perspectives of employees participating in the groups, the group facilitators and the service managers. The reflection groups were implemented as part of a research and development project. A mixed-methods design with qualitative focus group interviews, observations and written reports were used to evaluate. The study was conducted at two nursing homes, two home care districts and a residence for people with learning disabilities. Participants were employees, facilitators and service managers. The study was guided by ethical standard principles and was approved by the Norwegian Social Science Data Services. We found support for ethics reflection as a valuable measure to strengthen clinical practice. New and improved solutions, more cooperation between employees, and improved collaboration with patients and their families are some of the results. No negative experiences were found. Instead, the ethics reflection based on experiences and challenges in the workplace, was described as a win-win situation. The evaluation also revealed what is needed to succeed and useful tips for further development of ethics support in community health services. Ethics reflection groups focusing on ethical challenges from the participants' daily work were found to be significant for improved practice, collegial support and cooperation, personal and professional development among staff, facilitators and managers. Resources needed to succeed were managerial support, and anchoring ethics sessions in the routine of daily work.

  9. Evaluate VTS benefits: A case study of Zhoushan Port

    Directory of Open Access Journals (Sweden)

    Jun-Min Mou

    2015-12-01

    Full Text Available It has been well acknowledged that Vessel Traffic Services (VTS has played a growing important role to ensure the safety of navigation in the busy ports and waterways. However, the benefits produced by VTS are usually ignored by the public and private sectors. Besides, the previous evaluations generally exist following problems: (1 It is difficult to collect the data for the parameters in the evaluation models and/or the parameters are designed illogically; (2 Those models did not take the following factors into consideration such as reducing the frequency of coastal vessel patrolling and saving human and material resources; (3 It is difficult to clearly discriminate the benefits derived from VTS and non-VTS. In this paper, a framework is presented to calculate the benefits of VTS in China. Four key indicators (safety, traffic efficiency, environmental protection and reducing supervising cost and quantitative methods have been introduced into the framework. When calculating the benefits quantitatively, the traffic condition before the construction (expansion of the VTS has acted as a benchmark. For a case study, the project of the expansion of VTS in Zhoushan Port, East China was evaluated with 10-year data. According to the results, the largest contribution is from the benefit of environmental protection. Via Cost-benefit analysis the benefit cost ratio (B/C of the VTS is up to 5.248, which shows the benefits produced by VTS are considerable. The research could provide references for VTS benefits evaluation and investment optimizing.

  10. [Comparing audiological evaluation and screening: a study on presbycusis].

    Science.gov (United States)

    Samelli, Alessandra Giannella; Negretti, Camila Aparecida; Ueda, Kerli Saori; Moreira, Renata Rodrigues; Schochat, Eliane

    2011-01-01

    Given the high prevalence of presbycusis and the damage it brings about, a screening test can be useful in the identification of hearing loss in primary care. To estimate the prevalence of hearing loss in a representative sample of elderly people living at Butantan using an audiological screening method (questionnaire) and a basic audiological evaluation; to compare the results of the two kinds of evaluations, checking the validity of this tool for hearing loss screening. Cross sectional descriptive study. 200 individuals (above 60 years old, both genders) were randomly selected to undergo audiological screening (questionnaire). Another randomly selected group encompassed 100 individuals who were submitted to a set of audiological tests. Then, we compared the results from the two methods. There were no statistically significant associations between the questionnaire and the degree of hearing loss of the patients. The prevalence of hearing loss in our sample was of 56% in the screening and of 95% when checked by the audiological evaluation. Therefore, screening was not proven valid to assess hearing when compared to audiological evaluation.

  11. Space-time geostatistics for precision agriculture: a case study of NDVI mapping for a Dutch potato field

    NARCIS (Netherlands)

    Heuvelink, G.B.M.; Egmond, van F.M.

    2010-01-01

    Many environmental variables that are relevant to precision agriculture, such as crop and soil properties and climate, vary both in time and space. Farmers can often benefit greatly from accurate information about the status of these variables at any particular point in time and space to aid their

  12. Hungarian contribution to the Global Soil Organic Carbon Map (GSOC17) using advanced machine learning algorithms and geostatistics

    Science.gov (United States)

    Szatmári, Gábor; Laborczi, Annamária; Takács, Katalin; Pásztor, László

    2017-04-01

    The knowledge about soil organic carbon (SOC) baselines and changes, and the detection of vulnerable hot spots for SOC losses and gains under climate change and changed land management is still fairly limited. Thus Global Soil Partnership (GSP) has been requested to develop a global SOC mapping campaign by 2017. GSPs concept builds on official national data sets, therefore, a bottom-up (country-driven) approach is pursued. The elaborated Hungarian methodology suits the general specifications of GSOC17 provided by GSP. The input data for GSOC17@HU mapping approach has involved legacy soil data bases, as well as proper environmental covariates related to the main soil forming factors, such as climate, organisms, relief and parent material. Nowadays, digital soil mapping (DSM) highly relies on the assumption that soil properties of interest can be modelled as a sum of a deterministic and stochastic component, which can be treated and modelled separately. We also adopted this assumption in our methodology. In practice, multiple regression techniques are commonly used to model the deterministic part. However, this global (and usually linear) models commonly oversimplify the often complex and non-linear relationship, which has a crucial effect on the resulted soil maps. Thus, we integrated machine learning algorithms (namely random forest and quantile regression forest) in the elaborated methodology, supposing then to be more suitable for the problem in hand. This approach has enable us to model the GSOC17 soil properties in that complex and non-linear forms as the soil itself. Furthermore, it has enable us to model and assess the uncertainty of the results, which is highly relevant in decision making. The applied methodology has used geostatistical approach to model the stochastic part of the spatial variability of the soil properties of interest. We created GSOC17@HU map with 1 km grid resolution according to the GSPs specifications. The map contributes to the GSPs

  13. Photocatalytic degradation of rosuvastatin: Analytical studies and toxicity evaluations

    Energy Technology Data Exchange (ETDEWEB)

    Machado, Tiele Caprioli, E-mail: tiele@enq.ufrgs.br [Chemical Engineering Department, Federal University of Rio Grande do Sul, Rua Engenheiro Luiz Englert s/n, CEP: 90040-040 Porto Alegre, RS (Brazil); Pizzolato, Tânia Mara [Chemical Institute, Federal University of Rio Grande do Sul, Avenida Bento Gonçalves, 9500, CEP: 91501-970 Porto Alegre, RS (Brazil); Arenzon, Alexandre [Ecology Center, Federal University of Rio Grande do Sul, Avenida Bento Gonçalves, 9500, CEP: 91501-970 Porto Alegre, RS (Brazil); Segalin, Jeferson [Biotechnology Center, Federal University of Rio Grande do Sul, Avenida Bento Gonçalves, 9500, CEP: 91501-970 Porto Alegre, RS (Brazil); Lansarin, Marla Azário [Chemical Engineering Department, Federal University of Rio Grande do Sul, Rua Engenheiro Luiz Englert s/n, CEP: 90040-040 Porto Alegre, RS (Brazil)

    2015-01-01

    Photocatalytic degradation of rosuvastatin, which is a drug that has been used to reduce blood cholesterol levels, was studied in this work employing ZnO as catalyst. The experiments were carried out in a temperature-controlled batch reactor that was irradiated with UV light. Preliminary the effects of the photocatalyst loading, the initial pH and the initial rosuvastatin concentration were evaluated. The experimental results showed that rosuvastatin degradation is primarily a photocatalytic process, with pseudo-first order kinetics. The byproducts that were generated during the oxidative process were identified using nano-ultra performance liquid chromatography tandem mass spectrometry (nano-UPLC–MS/MS) and acute toxicity tests using Daphnia magna were done to evaluate the toxicity of the untreated rosuvastatin solution and the reactor effluent. - Highlights: • The photocatalytic degradation of rosuvastatin was studied under UV irradiation. • Commercial catalyst ZnO was used. • Initial rosuvastatin concentration, photocatalyst loading and pH were evaluated. • The byproducts generated during the oxidative process were detected and identified. • Acute toxicity tests using Daphnia magna were carried out.

  14. Wound assessment tools and nurses' needs: an evaluation study.

    Science.gov (United States)

    Greatrex-White, Sheila; Moxey, Helen

    2015-06-01

    The purpose of this study was to ascertain how well different wound assessment tools meet the needs of nurses in carrying out general wound assessment and whether current tools are fit for purpose. The methodology employed was evaluation research. In order to conduct the evaluation, a literature review was undertaken to identify the criteria of an optimal wound assessment tool which would meet nurses' needs. Several freely available wound assessment tools were selected based on predetermined inclusion and exclusion criteria and an audit tool was developed to evaluate the selected tools based on how well they met the criteria of the optimal wound assessment tool. The results provide a measure of how well the selected wound assessment tools meet the criteria of the optimal wound assessment tool. No tool was identified which fulfilled all the criteria, but two (the Applied Wound Management tool and the National Wound Assessment Form) met the most criteria of the optimal tool and were therefore considered to best meet nurses' needs in wound assessment. The study provides a mechanism for the appraisal of wound assessment tools using a set of optimal criteria which could aid practitioners in their search for the best wound assessment tool. © 2013 The Authors. International Wound Journal published by Medicalhelplines.com Inc and John Wiley & Sons Ltd.

  15. Studying the Foreign Experience of Evaluating Intellectual Potential of Organizations

    Directory of Open Access Journals (Sweden)

    Pererva Petro G.

    2016-01-01

    Full Text Available The use of intellectual capital (IC is considered in developed countries as a strategic management tool for achievement of the organizations' success in innovative activities. The article is aimed at studying the foreign experience of evaluating intellectual potential of organizations and identifying directions for its advancement and use at the domestic enterprises to improve their innovative activity. An approach to capital structure has been developed, in which the following three parts are allocated: human capital, structural capital, capital of interactions. The proposed general model for research of IC in terms of firm or region allows to evaluate not only the potential, but also several important lines of communication, namely: industrial-technological, market-customer, business environment and society, commercial operations (technology, value creation and the overall development strategy. In the proposed version of studying the IC potential, analytics are combined with management of both strategy and development tactics, based on use of resources of intellectual capital. The scheme of development management through the system of the activities of influence is recommended as well. The end result of the analytical project work provides the development package, which is issued as a supporting document of development strategy. Evaluation of the development level of intellectual capital in the context of individual enterprises and of regional complex in general has been recommended to include in the Regional innovation system (RIS as one of its functional tasks

  16. Quality evaluation of labneh: a study with consumers

    Directory of Open Access Journals (Sweden)

    Mariana Pereira Silveira

    2017-06-01

    Full Text Available The labneh (Greek yoghurt is a type of fermented milk product characterized by the concentration of the solids of the traditional yoghurt. The objectives of this study were to evaluate the acceptance of 3 commercial brands of traditional Greek yogurt marketed in the city of Diamantina/MG; and to identify the attributes that influence the quality of the product. Analysis of the color (L*, a*, b*, texture, acidity, pH and sensory evaluation were performed. It was observed variation among the samples regarding all analyzed parameters but b* value. In relation to the sensory evaluation, throughout the test of means, it was observed that the brands IA and IB were the most accepted. Through the preference map analysis, it could be concluded that the higher percent of lactic acid of the sample IA and the higher firmness of the sample IB were the parameters responsible for the greater acceptance of these brands. It was observed that the texture and acidity are important attributes related to the choice of the product. Therefore, the results of this study may help in future work of development of new formulations.

  17. The Risk-Stratified Osteoporosis Strategy Evaluation study (ROSE)

    DEFF Research Database (Denmark)

    Rubin, Katrine Hass; Holmberg, Teresa; Rothmann, Mette Juel

    2015-01-01

    The risk-stratified osteoporosis strategy evaluation study (ROSE) is a randomized prospective population-based study investigating the effectiveness of a two-step screening program for osteoporosis in women. This paper reports the study design and baseline characteristics of the study population....... 35,000 women aged 65-80 years were selected at random from the population in the Region of Southern Denmark and-before inclusion-randomized to either a screening group or a control group. As first step, a self-administered questionnaire regarding risk factors for osteoporosis based on FRAX......(®) was issued to both groups. As second step, subjects in the screening group with a 10-year probability of major osteoporotic fractures ≥15 % were offered a DXA scan. Patients diagnosed with osteoporosis from the DXA scan were advised to see their GP and discuss pharmaceutical treatment according to Danish...

  18. A Study of KHNP Nuclear Power Plant Technology Level Evaluation

    International Nuclear Information System (INIS)

    Yang, Seung Han; Lee, Sung Jin; Kim, Yo Han

    2016-01-01

    KHNP's 2030 mid and long term plan goal in technology field is securing global No. 1 NPP technology level. Quantifying technology level for this purpose, technology level at present should be surveyed. Technology level of South Korea has been surveyed by KISTEP (Korea Institute of S and T Evaluation and Planning) every two year but the technology level of KHNP has not been surveyed by any organization including KHNP itself. Also the size of technology surveyed by KISTEP was too broad to quantifying technology level of KHNP. In this paper, technology level of KHNP and South Korea are presented. In this study, NPP related technologies were divided into Level I and Level II technologies and conducted a survey for each Level II technologies using Delphi questionnaire survey that is widely used in technology level evaluation. The results of technology level and gap will be used from strategic point of view and also as a reference data for technology improvement planning

  19. Initial Results of an MDO Method Evaluation Study

    Science.gov (United States)

    Alexandrov, Natalia M.; Kodiyalam, Srinivas

    1998-01-01

    The NASA Langley MDO method evaluation study seeks to arrive at a set of guidelines for using promising MDO methods by accumulating and analyzing computational data for such methods. The data are collected by conducting a series of re- producible experiments. In the first phase of the study, three MDO methods were implemented in the SIGHT: framework and used to solve a set of ten relatively simple problems. In this paper, we comment on the general considerations for conducting method evaluation studies and report some initial results obtained to date. In particular, although the results are not conclusive because of the small initial test set, other formulations, optimality conditions, and sensitivity of solutions to various perturbations. Optimization algorithms are used to solve a particular MDO formulation. It is then appropriate to speak of local convergence rates and of global convergence properties of an optimization algorithm applied to a specific formulation. An analogous distinction exists in the field of partial differential equations. On the one hand, equations are analyzed in terms of regularity, well-posedness, and the existence and unique- ness of solutions. On the other, one considers numerous algorithms for solving differential equations. The area of MDO methods studies MDO formulations combined with optimization algorithms, although at times the distinction is blurred. It is important to

  20. Developmental neurotoxicity guideline study: issues with methodology, evaluation and regulation.

    Science.gov (United States)

    Tsuji, Ryozo; Crofton, Kevin M

    2012-09-01

    Recently social concerns have been increasing about the effects of environmental factors on children's health, especially on their nervous systems. The U.S. Environmental Protection Agency (EPA) and the Organisation for Economic Co-operation and Development (OECD) have published testing guidelines for developmental neurotoxicity (DNT). Approximately 110 guideline studies have been conducted to date. Importantly, information from these studies has provided data critical for regulatory decisions for a number of chemicals. However, the DNT guidelines do not always satisfy all stakeholders because of some uncertainties in their methodology, evaluation, and regulation. Methodological issues include incomplete harmonization between EPA and OECD guidelines, criticisms of the methodology for learning and memory testing, and unspecified positive control substances. Potential artifacts in morphometric neuropathological measures, criteria for observation measures, uncertainty of postnatal offspring exposure, especially in feeding studies, and extrapolation of data from rats to humans are major evaluation issues. In addition, there is some uncertainty in the use of an additional safety factor for susceptibility of infants and children. Moreover, the DNT guidelines have extensive time and cost requirements, use large numbers of animals, and there is a limited set of laboratories that can conduct the study. This paper reviews some of these issues and summarizes discussions from the symposium 'Developmental neurotoxicity testing: Scientific approaches towards the next generation to protecting the developing nervous system of children' held at the 2011 annual meeting of the Japanese Teratology Society. © 2012 The Authors. Congenital Anomalies © 2012 Japanese Teratology Society.

  1. [Evaluation of ear acupressure on painful shoulder syndrome: case study].

    Science.gov (United States)

    Zanelatto, Ana Paula

    2013-01-01

    The Painful Shoulder Syndrome (PSS) is defined as pain and functional limitation resulting from impairment of static and dynamic structures of the shoulder, such as ligaments, capsule and muscles. It is one of the most common and disabling of the musculoskeletal system in the general population with prevalence estimated between 15-25%. This study aimed to evaluate the results of auricular acupressure when used as therapy in the treatment of chronic pain secondary to SOD, and the analgesic effect and therapeutic satisfactory and the estimated time of treatment. To obtain the objective was to perform a case study was to intervene with auricular acupressure beads and crystals as an indicator of the outcome questionnaire Penn Shoulder Score (PSS - Brazil). Data were analyzed qualitatively and quantitatively. We conclude that auriculotherapy is an important therapeutic technique, because the study showed an improvement in the total score of the PSS - Brazil at 34.3%.

  2. Evaluating a problem based learning course: an action research study.

    Science.gov (United States)

    Walker, J; Bailey, S; Brasell-Brian, R; Gould, S

    2001-03-01

    Problem based learning (PBL) has been widely used in the United States, United Kingdom and Australasia in undergraduate nursing education to develop critical thinking and problem solving skills. PBL has been used since 1996 in a Bachelor of Nursing course at a New Zealand tertiary institution, and several modifications have been made to foster effective learning. The 'pure' PBL process has been adapted to move students gradually from teacher direction to taking responsibility for their learning. This has provided the opportunity for students to develop critical thinking, problem solving, information retrieval and evaluation skills, and group process skills over an 18-week period. Because rigorous evaluation of these changes had not been formally undertaken, the purpose of this study was to evaluate how the current format was developing students' understanding and integration of knowledge. Two cycles of the action research method (Cardno and Piggot-Irvine, 1994) were used, involving 4 lecturers and 17 students. Data was collected both quantitatively and qualitatively over a 16-week period. Findings indicated the importance of: explaining the purpose and process of PBL; communicating in detail the role of both students and lecturers; keeping communication lines open; addressing timetabling issues and valuing this method of learning for nursing practice. Implications for nursing education are addressed.

  3. Evaluating the ovarian cancer gonadotropin hypothesis: A candidate gene study

    Science.gov (United States)

    Lee, Alice W.; Tyrer, Jonathan P.; Doherty, Jennifer A.; Stram, Douglas A.; Kupryjanczyk, Jolanta; Dansonka-Mieszkowska, Agnieszka; Plisiecka-Halasa, Joanna; Spiewankiewicz, Beata; Myers, Emily J.; Chenevix-Trench, Georgia; Fasching, Peter A.; Beckmann, Matthias W.; Ekici, Arif B.; Hein, Alexander; Vergote, Ignace; Van Nieuwenhuysen, Els; Lambrechts, Diether; Wicklund, Kristine G.; Eilber, Ursula; Wang-Gohrke, Shan; Chang-Claude, Jenny; Rudolph, Anja; Sucheston-Campbell, Lara; Odunsi, Kunle; Moysich, Kirsten B.; Shvetsov, Yurii B.; Thompson, Pamela J.; Goodman, Marc T.; Wilkens, Lynne R.; Dörk, Thilo; Hillemanns, Peter; Dürst, Matthias; Runnebaum, Ingo B.; Bogdanova, Natalia; Pelttari, Liisa M.; Nevanlinna, Heli; Leminen, Arto; Edwards, Robert P.; Kelley, Joseph L.; Harter, Philipp; Schwaab, Ira; Heitz, Florian; du Bois, Andreas; Orsulic, Sandra; Lester, Jenny; Walsh, Christine; Karlan, Beth Y.; Hogdall, Estrid; Kjaer, Susanne K.; Jensen, Allan; Vierkant, Robert A.; Cunningham, Julie M.; Goode, Ellen L.; Fridley, Brooke L.; Southey, Melissa C.; Giles, Graham G.; Bruinsma, Fiona; Wu, Xifeng; Hildebrandt, Michelle A.T.; Lu, Karen; Liang, Dong; Bisogna, Maria; Levine, Douglas A.; Weber, Rachel Palmieri; Schildkraut, Joellen M.; Iversen, Edwin S.; Berchuck, Andrew; Terry, Kathryn L.; Cramer, Daniel W.; Tworoger, Shelley S.; Poole, Elizabeth M.; Olson, Sara H.; Orlow, Irene; Bandera, Elisa V.; Bjorge, Line; Tangen, Ingvild L.; Salvesen, Helga B.; Krakstad, Camilla; Massuger, Leon F.A.G.; Kiemeney, Lambertus A.; Aben, Katja K.H.; van Altena, Anne M.; Bean, Yukie; Pejovic, Tanja; Kellar, Melissa; Le, Nhu D.; Cook, Linda S.; Kelemen, Linda E.; Brooks-Wilson, Angela; Lubinski, Jan; Gronwald, Jacek; Cybulski, Cezary; Jakubowska, Anna; Wentzensen, Nicolas; Brinton, Louise A.; Lissowska, Jolanta; Yang, Hannah; Nedergaard, Lotte; Lundvall, Lene; Hogdall, Claus; Song, Honglin; Campbell, Ian G.; Eccles, Diana; Glasspool, Rosalind; Siddiqui, Nadeem; Carty, Karen; Paul, James; McNeish, Iain A.; Sieh, Weiva; McGuire, Valerie; Rothstein, Joseph H.; Whittemore, Alice S.; McLaughlin, John R.; Risch, Harvey A.; Phelan, Catherine M.; Anton-Culver, Hoda; Ziogas, Argyrios; Menon, Usha; Ramus, Susan J.; Gentry-Maharaj, Aleksandra; Harrington, Patricia; Pike, Malcolm C.; Modugno, Francesmary; Rossing, Mary Anne; Ness, Roberta B.; Pharoah, Paul D.P.; Stram, Daniel O.; Wu, Anna H.; Pearce, Celeste Leigh

    2016-01-01

    Objective Ovarian cancer is a hormone-related disease with a strong genetic basis. However, none of its high-penetrance susceptibility genes and GWAS-identified variants to date are known to be involved in hormonal pathways. Given the hypothesized etiologic role of gonadotropins, an assessment of how variability in genes involved in the gonadotropin signaling pathway impacts disease risk is warranted. Methods Genetic data from 41 ovarian cancer study sites were pooled and unconditional logistic regression was used to evaluate whether any of the 2185 SNPs from 11 gonadotropin signaling pathway genes was associated with ovarian cancer risk. A burden test using the admixture likelihood (AML) method was also used to evaluate gene-level associations. Results We did not find any genome-wide significant associations between individual SNPs and ovarian cancer risk. However, there was some suggestion of gene-level associations for four gonadotropin signaling pathway genes: INHBB (p = 0.045, mucinous), LHCGR (p = 0.046, high-grade serous), GNRH (p = 0.041, high-grade serous), and FSHB (p = 0.036, overall invasive). There was also suggestive evidence for INHA (p = 0.060, overall invasive). Conclusions Ovarian cancer studies have limited sample numbers, thus fewer genome-wide susceptibility alleles, with only modest associations, have been identified relative to breast and prostate cancers. We have evaluated the majority of ovarian cancer studies with biological samples, to our knowledge, leaving no opportunity for replication. Using both our understanding of biology and powerful gene-level tests, we have identified four putative ovarian cancer loci near INHBB, LHCGR, GNRH, and FSHB that warrant a second look if larger sample sizes and denser genotype chips become available. PMID:25528498

  4. Identifying and closing gaps in environmental monitoring by means of metadata, ecological regionalization and geostatistics using the UNESCO biosphere reserve Rhoen (Germany) as an example.

    Science.gov (United States)

    Schröder, Winfried; Pesch, Roland; Schmidt, Gunther

    2006-03-01

    In Germany, environmental monitoring is intended to provide a holistic view of the environmental condition. To this end the monitoring operated by the federal states must use harmonized, resp., standardized methods. In addition, the monitoring sites should cover the ecoregions without any geographical gaps, the monitoring design should have no gaps in terms of ecologically relevant measurement parameters, and the sample data should be spatially without any gaps. This article outlines the extent to which the Rhoen Biosphere Reserve, occupying a part of the German federal states of Bavaria, Hesse and Thuringia, fulfills the listed requirements. The investigation considered collection, data banking and analysis of monitoring data and metadata, ecological regionalization and geostatistics. Metadata on the monitoring networks were collected by questionnaires and provided a complete inventory and description of the monitoring activities in the reserve and its surroundings. The analysis of these metadata reveals that most of the monitoring methods are harmonized across the boundaries of the three federal states the Rhoen is part of. The monitoring networks that measure precipitation, surface water levels, and groundwater quality are particularly overrepresented in the central ecoregions of the biosphere reserve. Soil monitoring sites are more equally distributed within the ecoregions of the Rhoen. The number of sites for the monitoring of air pollutants is not sufficient to draw spatially valid conclusions. To fill these spatial gaps, additional data on the annual average values of the concentrations of air pollutants from monitoring sites outside of the biosphere reserve had therefore been subject to geostatistical analysis and estimation. This yields valid information on the spatial patterns and temporal trends of air quality. The approach illustrated is applicable to similar cases, as, for example, the harmonization of international monitoring networks.

  5. Estimating the number of cases of podoconiosis in Ethiopia using geostatistical methods [version 2; referees: 3 approved, 1 approved with reservations

    Directory of Open Access Journals (Sweden)

    Kebede Deribe

    2017-12-01

    Full Text Available Background: In 2011, the World Health Organization recognized podoconiosis as one of the neglected tropical diseases. Nonetheless, the  magnitude of podoconiosis and the geographical distribution of the disease is poorly understood. Based on a nationwide mapping survey and geostatistical modelling, we predict the prevalence of podoconiosis and estimate the number of cases across Ethiopia. Methods: We used nationwide data collected in Ethiopia between 2008 and 2013. Data were available for 141,238 individuals from 1,442 communities in 775 districts from all nine regional states and two city administrations. We developed a geostatistical model of podoconiosis prevalence among adults (individuals aged 15 years or above, by combining environmental factors. The number of people with podoconiosis was then estimated using a gridded map of adult population density for 2015. Results: Podoconiosis is endemic in 345 districts in Ethiopia: 144 in Oromia, 128 in Southern Nations, Nationalities and People’s [SNNP], 64 in Amhara, 4 in Benishangul Gumuz, 4 in Tigray and 1 in Somali Regional State. Nationally, our estimates suggest that 1,537,963 adults (95% confidence intervals, 290,923-4,577,031 adults were living with podoconiosis in 2015. Three regions (SNNP, Oromia and Amhara contributed 99% of the cases. The highest proportion of individuals with podoconiosis resided in the SNNP (39%, while 32% and 29% of people with podoconiosis resided in Oromia and Amhara Regional States, respectively. Tigray and Benishangul Gumuz Regional States bore lower burdens, and in the remaining regions, podoconiosis was almost non-existent.  Conclusions: The estimates of podoconiosis cases presented here based upon the combination of currently available epidemiological data and a robust modelling approach clearly show that podoconiosis is highly endemic in Ethiopia. Given the presence of low cost prevention, and morbidity management and disability prevention services, it is

  6. Synthesis, Computational Studies and Preliminary Pharmacological Evaluation of New Arylpiperazines

    Directory of Open Access Journals (Sweden)

    Sushil Kumar

    2011-01-01

    Full Text Available A series of novel arylpiperazines were synthesized and the target compounds evaluated for atypical antipsychotic activity in apomorphine induced climbing behavior (D2 antagonism, 5-HTP induced head twitches (5-HT2A antagonism and catalepsy studies in albino mice. The physicochemical similarity of the target compounds with respect to standard drugs clozapine, ketanserine and risperidone was assessed by calculating from a set of physiochemical properties using software programs. The test compounds (3a-j demonstrated good similarity values with respect to the standard drugs. Among them, compound 3d has emerged as an important lead compound showing potential atypical antipsychotic like profile.

  7. A Study on the improvement of Paldang dam discharge evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Song, Young Chul; Kim, Chong Hak; Lee, Dae Soo [Korea Electric Power Corp. (KEPCO), Taejon (Korea, Republic of). Research Center; Lee, Won Hwan; Cho, Won Chul; Heo, Jun Haeng [Yonsei Univ., Seoul (Korea, Republic of)

    1995-12-31

    Besides the original purpose of electric power generation, the Paldang dam plays such important roles as flood control and water supply in the Han river. However, significant drawdown of the downstream water level since 1973 has caused considerable differences between the real discharges and the estimated values currently in use. This study was performed to improve discharge evaluation method and to provide new discharge table appropriate for the changed condition. Through the physical model tests assisted by numerical test, the discharge equations were modified, the discharge table was revised for steady and unsteady flow conditions, but the gate operation rules proved reasonable and remained unchanged. (author). 81 refs., 166 figs.

  8. Synthesis, antimicrobial evaluation and QSAR studies of gallic acid derivatives

    Directory of Open Access Journals (Sweden)

    Anurag Khatkar

    2017-05-01

    Full Text Available A series of gallic acid derivatives (1–33 was synthesized and characterized by physicochemical and spectral means. The synthesized compounds were evaluated in vitro for their antimicrobial activity against different Gram positive and Gram negative bacterial and fungal strains by the tube dilution method. Results of antimicrobial screening indicated that compound 6 was the most active antimicrobial agent (pMICam = 1.92 μM/mL. The results of QSAR studies demonstrated that antibacterial, antifungal and overall antimicrobial activities of synthesized gallic acid derivatives were governed by the electronic parameters, cosmic total energy (Cos E. and nuclear energy (Nu. E..

  9. Complications to evaluate adult trauma care: An expert consensus study.

    Science.gov (United States)

    Moore, Lynne; Lauzier, François; Stelfox, Henry Thomas; Le Sage, Natalie; Bourgeois, Gilles; Clément, Julien; Shemilt, Michèle; Turgeon, Alexis F

    2014-08-01

    Complications affect up to 37% of patients hospitalized for injury and increase mortality, morbidity, and costs. One of the keys to controlling complications for injury admissions is to monitor in-hospital complication rates. However, there is no consensus on which complications should be used to evaluate the quality of trauma care. The objective of this study was to develop a consensus-based list of complications that can be used to assess the acute phase of adult trauma care. We used a three-round Web-based Delphi survey among experts in the field of trauma care quality with a broad range of clinical expertise and geographic diversity. The main outcome measure was median importance rating on a 5-point Likert scale (very low to very high); complications with a median of 4 or greater and no disagreement were retained. A secondary measure was the perceived quality of information on each complication available in patient files. Of 19 experts invited to participate, 17 completed the first (brainstorming) round and 16 (84%) completed all rounds. Of 73 complications generated in Round 1, a total of 25 were retained including adult respiratory distress syndrome, hospital-acquired pneumonia, sepsis, acute renal failure, deep vein thrombosis, pulmonary embolism, wound infection, decubitus ulcers, and delirium. Of these, 19 (76%) were perceived to have high-quality or very high-quality information in patient files by more than 50% of the panel members. This study proposes a consensus-based list of 25 complications that can be used to evaluate the quality of acute adult trauma care. These complications can be used to develop an informative and actionable quality indicator to evaluate trauma care with the goal of decreasing rates of hospital complications and thus improving patient outcomes and resource use. DRG International Classification of Diseases codes are provided.

  10. Leadership development through action learning sets: an evaluation study.

    Science.gov (United States)

    Walia, Surinder; Marks-Maran, Di

    2014-11-01

    This article examines the use of action learning sets in a leadership module delivered by a university in south east England. An evaluation research study was undertaking using survey method to evaluate student engagement with action learning sets, and their value, impact and sustainability. Data were collected through a questionnaire with a mix of Likert-style and open-ended questions and qualitative and quantitative data analysis was undertaken. Findings show that engagement in the action learning sets was very high. Action learning sets also had a positive impact on the development of leadership knowledge and skills and are highly valued by participants. It is likely that they would be sustainable as the majority would recommend action learning to colleagues and would consider taking another module that used action learning sets. When compared to existing literature on action learning, this study offers new insights as there is little empirical literature on student engagement with action learning sets and even less on value and sustainability. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Encouraging Stakeholder Engagement: A Case Study of Evaluator Behavior

    Science.gov (United States)

    Poth, Cheryl-Anne; Shulha, Lyn

    2008-01-01

    This chapter describes evaluator behaviors revealed by the case analysis of a participatory and developmental evaluation. The analysis revealed that the evaluator paid specific attention to individual stakeholder cues. These cues were related to three elements of the evaluation: negotiating the design, monitoring individual stakeholder needs, and…

  12. Evaluating midwifery units (EMU): lessons from the pilot study.

    Science.gov (United States)

    Monk, Amy R; Tracy, Sally K; Foureur, Maralyn; Tracy, Mark

    2013-08-01

    this paper describes the pilot study that was undertaken to test the feasibility of the recruitment plan designed to recruit women who booked to give birth in two freestanding midwifery units in NSW, Australia. The pilot preceded the full prospective cohort study, Evaluating Midwifery Units (EMU), which aimed to examine the antenatal, birth and postnatal outcomes of women planning to give birth in freestanding midwifery units compared to those booked to give birth in tertiary level maternity units in Australia and New Zealand. a prospective cohort study with two mutually-exclusive cohorts. two freestanding midwifery units in NSW and their corresponding tertiary referral hospitals. a total of 146 women with few identified risk factors recruited between 13 September 2009 and 31 March 2010 whose planned place of birth was either a freestanding midwifery unit or tertiary maternity unit. the pilot study identified the feasibility of relying on the booking midwife to recruit eligible women from several antenatal booking clinics to the study. Low rates of eligible women were invited resulting in a lower than expected consent rate. In addition, although mostly only low-risk women were invited to participate, some women requiring medical consultation at the time of booking were inadvertently recruited into the study. The results of this pilot study led us to revise the study protocol to find ways of including the outcomes of all women without identified risk factors who booked at either the freestanding midwifery units or the tertiary referral hospital in that area. This paper describes the revisions that were made to the study plan. five lessons were learned from the pilot study. We found that recruitment protocols employed for the cohort study were too complicated and required simplification to maximise the potential of the study. The study protocol needed to be changed for the main study to ensure a larger sample size and to ensure the risk profile of each cohort was as

  13. Longitudinal Evaluation of Transition Services ("LETS Study"): protocol for outcome evaluation.

    Science.gov (United States)

    Tsybina, Irina; Kingsnorth, Shauna; Maxwell, Joanne; Bayley, Mark; Lindsay, Sally; McKeever, Patricia; Colantonio, Angela; Hamdani, Yani; Healy, Helen; Macarthur, Colin

    2012-05-15

    Because of advances in medical treatment, most children with physical disabilities can expect to achieve near normal life spans. Typically, coordinated teams of health care providers in specialized pediatric settings care for these children. As these children reach adulthood, however, the availability of services and expertise changes because the adult health care system has different processes designed to meet their specialized needs. Gaps in continuity of care during the transition from pediatric to adult services, and associated poor health outcomes are well documented. In response, new models of care are being introduced to address the complex process of health care transition. This paper describes a study protocol of a client-centred, prospective, longitudinal, mixed-method evaluation of linked model of health care across the lifespan (the LIFEspan Model), offered by a pediatric rehabilitation centre and an adult rehabilitation centre. This project will include a process and an outcome evaluation of the LIFEspan Model. The process evaluation will detail the specific service delivery that occurs with respect to preparation for transition and transfer of care through chart audits of pediatric medical records and qualitative interviews with LIFEspan staff. The outcome evaluation will measure the effect of the model on: 1) maintaining continuity within the health care system from pediatric to adult care; and 2) secondary outcomes related to health, well-being, social participation, transition readiness, and health care utilization of youth with cerebral palsy and acquired brain injury. Standardized instruments will include Health Utilities Inventory, Assessment of Life Habits, Arc's Self-Determination, Assessment of Health-Related Quality of Life, Partners in Health Questionnaire, Social Support Questionnaire, and Self-Efficacy for Managing Chronic Disease. The LETS study will be original in its undertaking of a prospective examination of outcomes 1-year post

  14. Evaluation of Social Studies Programme in Government Teachers' Colleges of Borno State, Nigeria. African Studies in Curriculum Development & Evaluation No. 31.

    Science.gov (United States)

    Samba, Wutama Bulama; And Others

    The effectiveness of social studies instruction in the Nigerian state of Borno was investigated with emphasis on teachers' skills. The study had three objectives: (1) to evaluate preservice teacher education social studies programs in terms of their objectives, curricula, methods, media, and evaluation procedures; (2) to evaluate teachers' skills…

  15. EVALUATION OF MEDIASTINAL TUMOURS: A STUDY OF 50 CASES

    Directory of Open Access Journals (Sweden)

    Prema K. R

    2016-06-01

    Full Text Available INTRODUCTION Mediastinum is a site for neoplastic and non-neoplastic lesions and many of them present as mediastinal mass. The location and composition of these lesions are critical in arriving at a clinical diagnosis. This study of different mediastinal masses is aimed to find out frequency of malignancy, their compartmental distribution and characteristics through computed tomography. MATERIALS AND METHODS A prospective study was conducted at Government Medical College, Thrissur, India, during the period 2010-2012 with a total of 50 patients with suspected mediastinal masses. All patients were subjected to investigations like chest X-ray, CT scan along with guided fine needle aspiration/biopsy for definite tissue diagnosis. The major variables were age, clinical symptoms, mass location, imaging studies, and tissue pathology. RESULT Fifty patients enrolled in this study were analysed and compared with existing studies in the literature. 34 cases (68% were malignant and 16 cases (32% were benign. Majority of the lesions were seen in the anterior compartment, followed by posterior compartment. Bronchogenic carcinoma and lymphoma were the common malignant tumours seen in the anterior and middle compartments of the mediastinum, whereas neurogenic tumours, mostly benign, were the common tumours in the posterior compartment. CONCLUSION CT scan is an effective tool in evaluating mediastinal masses. Moreover, sampling the mass is important in obtaining pathological diagnosis. Surgery, radiotherapy and chemotherapy either as single or in combination are the main modalities of treatment. Accurate preoperative pathological diagnosis, invasion and infiltration of the tumour were the key to successful treatment.

  16. Evaluation of an accelerated mineralization process for ashes - feasibility study; Evaluering av jordmaansbildande askbehandlingsprocess (EJA) - foerstudie

    Energy Technology Data Exchange (ETDEWEB)

    Ecke, Holger; Bjurstroem, Henrik

    2005-03-01

    In Japan, expenses for landfilling yield about 400 USD per ton of ash, which gives an incentive to reduce the amount of landfilled ash. At NIES (National Institute for Environmental Studies) in Tsukuba, Japan, the AMT process (Accelerated Mineralization Technology) was developed aiming at the treatment of ashes and production of soil-like material for reuse. The objective of the project EJA was to evaluate the AMT process on the basis of available information and the possibilities the process could offer with respect to the conditions present in Sweden. With support of researchers at NIES, available literature including unpublished manuscripts on the AMT process was compiled, translated and evaluated. During treatment, the ashes are washed, aged and mixed with up to 5 % by weight of biodegradable organic matter. The material is stabilized at landfill. During up to several decades, metals are demobilized through a combination of three mechanisms, viz. carbonation, clay formation, and humification. Also persistent organic pollutants (POP) are demobilized due to humification products or they are degraded anaerobically. When the treatment is completed, the reuse of the material is envisaged. Due to the long treatment period, the AMT method might not be favored by ash producers in Sweden. In the future, landfill companies could be interested in the technology, since they are experienced to handle waste at long sight. This, however, requires that the legislation does not pose any hindrance for the implementation of the method, e.g. regarding the requirement to add organic matter to the ash. Above all, it remains several years of research on the AMT process to fully understand and evaluate the underlying biological and chemical processes as well as their interaction.

  17. An inventory of evaluation studies of information technology in health care - Trends in evaluation research 1982-2002

    NARCIS (Netherlands)

    Ammenwerth, E.; de Keizer, N.

    2005-01-01

    Objectives: During the last years the significance of evaluation studies as well as the interest in adequate Methods and approaches for evaluation has grown in medical informatics. In order to put this discussion into historical perspective of evaluation research, we conducted a systematic review on

  18. An inventory of evaluation studies of information technology in health care: trends in evaluation research 1982-2002

    NARCIS (Netherlands)

    Ammenwerth, Elske; de Keizer, Nicolette

    2004-01-01

    During the last years the significance of evaluation studies as well as the interest in adequate methods and approaches for evaluation has grown in medical informatics. In order to put this discussion into the historical context of evaluation research, we conducted a systematic overview on trends in

  19. A conceptual framework for evaluating data suitability for observational studies.

    Science.gov (United States)

    Shang, Ning; Weng, Chunhua; Hripcsak, George

    2017-09-08

    To contribute a conceptual framework for evaluating data suitability to satisfy the research needs of observational studies. Suitability considerations were derived from a systematic literature review on researchers' common data needs in observational studies and a scoping review on frequent clinical database design considerations, and were harmonized to construct a suitability conceptual framework using a bottom-up approach. The relationships among the suitability categories are explored from the perspective of 4 facets of data: intrinsic, contextual, representational, and accessible. A web-based national survey of domain experts was conducted to validate the framework. Data suitability for observational studies hinges on the following key categories: Explicitness of Policy and Data Governance, Relevance, Availability of Descriptive Metadata and Provenance Documentation, Usability, and Quality. We describe 16 measures and 33 sub-measures. The survey uncovered the relevance of all categories, with a 5-point Likert importance score of 3.9 ± 1.0 for Explicitness of Policy and Data Governance, 4.1 ± 1.0 for Relevance, 3.9 ± 0.9 for Availability of Descriptive Metadata and Provenance Documentation, 4.2 ± 1.0 for Usability, and 4.0 ± 0.9 for Quality. The suitability framework evaluates a clinical data source's fitness for research use. Its construction reflects both researchers' points of view and data custodians' design features. The feedback from domain experts rated Usability, Relevance, and Quality categories as the most important considerations. © The Author 2017. Published by Oxford University Press on behalf of the American Medical Informatics Association. All rights reserved. For Permissions, please email: journals.permissions@oup.com

  20. A multi-analysis approach for space-time and economic evaluation of risks related with livestock diseases: the example of FMD in Peru.

    Science.gov (United States)

    Martínez-López, B; Ivorra, B; Fernández-Carrión, E; Perez, A M; Medel-Herrero, A; Sánchez-Vizcaíno, F; Gortázar, C; Ramos, A M; Sánchez-Vizcaíno, J M

    2014-04-01

    This study presents a multi-disciplinary decision-support tool, which integrates geo-statistics, social network analysis (SNA), spatial-stochastic spread model, economic analysis and mapping/visualization capabilities for the evaluation of the sanitary and socio-economic impact of livestock diseases under diverse epidemiologic scenarios. We illustrate the applicability of this tool using foot-and-mouth disease (FMD) in Peru as an example. The approach consisted on a flexible, multistep process that may be easily adapted based on data availability. The first module (mI) uses a geo-statistical approach for the estimation (if needed) of the distribution and abundance of susceptible population (in the example here, cattle, swine, sheep, goats, and camelids) at farm-level in the region or country of interest (Peru). The second module (mII) applies SNA for evaluating the farm-to-farm contact patterns and for exploring the structure and frequency of between-farm animal movements as a proxy for potential disease introduction or spread. The third module (mIII) integrates mI-II outputs into a spatial-stochastic model that simulates within- and between-farm FMD-transmission. The economic module (mIV) connects outputs from mI-III to provide an estimate of associated direct and indirect costs. A visualization module (mV) is also implemented to graph and map the outputs of module I-IV. After 1000 simulated epidemics, the mean (95% probability interval) number of outbreaks, infected animals, epidemic duration, and direct costs were 37 (1, 1164), 2152 (1, 13, 250), 63 days (0, 442), and US$ 1.2 million (1072, 9.5 million), respectively. Spread of disease was primarily local (Peru, in particular to inform and support the implementation of risk-based surveillance and livestock insurance systems that may help to prevent and control potential FMD virus incursions into Peru. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Evaluation of Xerostomia in Different Psychological Disorders: An Observational Study.

    Science.gov (United States)

    Veerabhadrappa, Suresh Kandagal; Chandrappa, Pramod Redder; Patil, Snehal; Roodmal, Seema Yadav; Kumarswamy, Akshay; Chappi, Mounesh Kumar

    2016-09-01

    Psychiatric diseases like anxiety, depression, schizophrenia and bipolar disorders are increasing at an alarming rate. These diseases can affect the quantity and quality of saliva leading to multiple oral diseases. Although many researchers have evaluated xerostomia in general population, its prevalence is not been assessed in patients suffering from different psychological disorders. To investigate the prevalence of xerostomia and to assess the correlation between xerostomia and dryness of lip and mucosa in different psychological disorders. A cross-sectional observational study was conducted over a period of six months in Department of Psychiatry and Department of Oral Medicine. Patients with anxiety, depression, schizophrenia and bipolar disorder, as diagnosed by an experienced psychiatrist, were given a questionnaire to evaluate the xerostomia. Patients with symptoms of xerostomia were subjected to oral examination by a skilled oral diagnostician to check for dryness of lips and mucosa. One hundred patients from each group of psychiatric diseases were included in the study using a consecutive sampling technique. An equal number of healthy individuals reporting to oral medicine department for routine oral screening were included as control group after initial psychiatric evaluation. In this study statistically significant increase in the xerostomia in psychiatric patients was recorded when compared to the control group (pXerostomia was significantly higher in anxiety patients (51%) followed by depression (47%), bipolar disorder (41%), schizophrenia (39%) and control group (27%). The majority of the psychiatric patients had 'moderate' to 'severe' xerostomia whereas the control group had 'mild' xerostomia. Xerostomia was significantly higher in younger age group (18-49 years) than in older age group and females patients had higher xerostomia than male patients. Psychiatric patients had significantly more dryness of lip and mucosa than healthy controls. A moderate

  2. A STUDY TO EVALUATE THE LEVELS OF DIOXIN-LIKE ...

    Science.gov (United States)

    The Environmental Protection Agency (EPA), in cooperation with USDA and the US Food and Drug Administration (FDA), has undertaken a program to study the presence of dioxin-like compounds in animal feeds. Two phases of this program have been completed, and this paper reports on the third phase. The first phase was a study on the mass balance of dioxins in lactating cows. The objective of that study was to quantify the role feeds play in total dairy cow exposures. The second phase of the program involved the collections and measurement of dioxins in minor feed components. Dioxins in specific targeted animal feed components of interest, including animal and plant byproducts were measured. The third phase involved sampling of total mixed dairy feeds and feed components from dairy facilities around the United States, and measuring for dioxin-like compounds. Lorber, M; Ferrario, J; Byrne, C; Greene, C; Cyrus, A. 2004. A Study to Evaluate the Levels of Dioxin-Like Compounds in Dairy Feeds in the United States. Organohalogen Compounds 66: 1958-1965. journal articles

  3. Evaluating health effects of transport interventions methodologic case study.

    Science.gov (United States)

    Ogilvie, David; Mitchell, Richard; Mutrie, Nanette; Petticrew, Mark; Platt, Stephen

    2006-08-01

    There is little evidence about the effects of environmental interventions on population levels of physical activity. Major transport projects may promote or discourage physical activity in the form of walking and cycling, but researching the health effects of such "natural experiments" in transport policy or infrastructure is challenging. Case study of attempts in 2004-2005 to evaluate the effects of two major transport projects in Scotland: an urban congestion charging scheme in Edinburgh, and a new urban motorway (freeway) in Glasgow. These interventions are typical of many major transport projects. They are unique to their context. They cannot easily be separated from the other components of the wider policies within which they occur. When, where, and how they are implemented are political decisions over which researchers have no control. Baseline data collection required for longitudinal studies may need to be planned before the intervention is certain to take place. There is no simple way of defining a population or area exposed to the intervention or of defining control groups. Changes in quantitative measures of health-related behavior may be difficult to detect. Major transport projects have clear potential to influence population health, but it is difficult to define the interventions, categorize exposure, or measure outcomes in ways that are likely to be seen as credible in the field of public health intervention research. A final study design is proposed in which multiple methods and spatial levels of analysis are combined in a longitudinal quasi-experimental study.

  4. An updated summary of MATHEW/ADPIC model evaluation studies

    Energy Technology Data Exchange (ETDEWEB)

    Foster, K.T.; Dickerson, M.H.

    1990-05-01

    This paper summarizes the major model evaluation studies conducted for the MATHEW/ADPIC atmospheric transport and diffusion models used by the US Department of Energy's Atmospheric Release Advisory Capability. These studies have taken place over the last 15 years and involve field tracer releases influenced by a variety of meteorological and topographical conditions. Neutrally buoyant tracers released both as surface and elevated point sources, as well as material dispersed by explosive, thermally bouyant release mechanisms have been studied. Results from these studies show that the MATHEW/ADPIC models estimate the tracer air concentrations to within a factor of two of the measured values 20% to 50% of the time, and within a factor of five of the measurements 35% to 85% of the time depending on the complexity of the meteorology and terrain, and the release height of the tracer. Comparisons of model estimates to peak downwind deposition and air concentration measurements from explosive releases are shown to be generally within a factor of two to three. 24 refs., 14 figs., 3 tabs.

  5. An updated summary of MATHEW/ADPIC model evaluation studies

    International Nuclear Information System (INIS)

    Foster, K.T.; Dickerson, M.H.

    1990-05-01

    This paper summarizes the major model evaluation studies conducted for the MATHEW/ADPIC atmospheric transport and diffusion models used by the US Department of Energy's Atmospheric Release Advisory Capability. These studies have taken place over the last 15 years and involve field tracer releases influenced by a variety of meteorological and topographical conditions. Neutrally buoyant tracers released both as surface and elevated point sources, as well as material dispersed by explosive, thermally bouyant release mechanisms have been studied. Results from these studies show that the MATHEW/ADPIC models estimate the tracer air concentrations to within a factor of two of the measured values 20% to 50% of the time, and within a factor of five of the measurements 35% to 85% of the time depending on the complexity of the meteorology and terrain, and the release height of the tracer. Comparisons of model estimates to peak downwind deposition and air concentration measurements from explosive releases are shown to be generally within a factor of two to three. 24 refs., 14 figs., 3 tabs

  6. Phylloplane fungi in Hong Kong mangroves: evaluation of study methods.

    Science.gov (United States)

    Lee, Olive H K; Hyde, Kevin D

    2002-01-01

    Many methods have been used to study phylloplane fungi, most of which have constraints and may result in biased results. This study used light microscopy and scanning electron microscopy (SEM) to investigate fungal abundance on the leaves of the most common mangrove trees in Hong Kong, Kandelia candel and Aegiceras corniculatum. Species richness was investigated using light microscopy and a leaf washing method. Methods to study phylloplane fungi are discussed and the performances of these three investigation methods are evaluated. Seven mitosporic fungal taxa were found by light microscopy, while 30 sporulating taxa and 18 Mycelia sterilia were isolated using the leaf washing method. Fungal abundance in terms of percentage cover investigated with light microscopy was similar using the SEM method, and was significantly higher on Aegiceras corniculatum than on Kandelia candel. Fungal abundance peaked in the summer and was lowest in the winter. This study indicates that light microscopy reveals the most typical phylloplane fungi and is more efficient than SEM, while the leaf washing method reveals many casual species and is not quantitative.

  7. A Study for Semantic Evaluation of Street Trees

    Directory of Open Access Journals (Sweden)

    Banu Çiçek Kurdoğlu

    2011-11-01

    Full Text Available The decline of green areas due to rapid urbanization has brought many problems to our cities. In order to overcome these problems, some systems enabling green continuity in cities are being studied. In these studies, ideas are carried out, concepts are discussed and projects and applications are put into practice to produce some approaches including greenways, urban forests, urban parks, considered as parts of these systems. Street trees occupy an important place within this green-area scenario. In this study, the contribution of street trees to city, citizens and open green-area system is investigated. For this purpose, students from the Department of Landscape Architecture and the Department of Forest Engineering (15 students from each department have evaluated some pictures of the city. Some analyses have been done on the data obtained through this assessment. Results showed that street trees create images that are interesting, full, continuous, effective and with identity and according to the result of non parametric correlation analysis performed on the data of implementation study, significant relationships has been identified between these parameters.

  8. Translation Evaluation: A Comparative Study of an Oblique Translation

    Directory of Open Access Journals (Sweden)

    / Esmail Zare Behtash

    2017-06-01

    Full Text Available Translation is of an absolute necessity in today’s world. Robinson (1997 states that the study of translation is an integral part of intercultural relations and of conveying scientific and technological knowledge. He further mentions that “translators need to be able to process linguistic materials quickly and efficiently; but they also need to be able to recognize problem areas and to slow down to solve them in complex analytical ways” (p. 2. This study is an attempt to explore and evaluate an oblique translation of a text from English into Persian to find the most frequent translation strategy. To reach the goal of the study, the researchers selected one hundred and ten sentences of an original English text which had been translated freely at random and compared them with their Persian counterparts. The findings of the study indicated that Persian translator used equivalent strategy with the highest percentage (45% in the translated corpus. After that, modulation, and transposition had the highest percentages respectively.

  9. Evaluating and operationalizing an environmental auditing program: a pilot study.

    Science.gov (United States)

    Gordon, Laura; Bruce, Natalie; Suh, Kathryn N; Roth, Virginia

    2014-07-01

    Environmental auditing is an important tool to ensure consistent and effective cleaning. Our pilot study compared an alcohol-based fluorescent marking product and an adenosine-5'-triphosphate bioluminescence product for use in an environmental auditing program to determine which product was more practical and acceptable to users. Both products were tested on 15 preselected high touch objects in randomly selected patient rooms, following regular daily cleaning. A room was considered a "pass" if ≥80% of surfaces were adequately cleaned as defined by manufacturers' guidelines. A qualitative survey assessed user preference and operational considerations. Using fluorescent marking, 9 of 37 patient rooms evaluated (24%) were considered a "pass" after daily cleaning. Using adenosine-5'-triphosphate bioluminescence, 21 of 37 patient rooms passed (57%). There was great variability in results between different high touch objects. Eighty percent of users preferred the alcohol-based fluorescent marking product because it provided an effective visual aid to coach staff on proper cleaning techniques and allowed simple and consistent application. Environmental auditing using translucent, alcohol-based fluorescent marking best met the requirements of our organization. Our results reinforce the importance of involving a multidisciplinary team in evaluating and operationalizing an environmental auditing program. Copyright © 2014 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Mosby, Inc. All rights reserved.

  10. Evaluating website quality: Five studies on user-focused evaluation methods

    NARCIS (Netherlands)

    Elling, S.K.

    2012-01-01

    The benefits of evaluating websites among potential users are widely acknowledged. There are several methods that can be used to evaluate the websites’ quality from a users’ perspective. In current practice, many evaluations are executed with inadequate methods that lack research-based validation.

  11. Evaluation of E-learning Platforms: a Case Study

    Directory of Open Access Journals (Sweden)

    Cristina POP

    2012-01-01

    Full Text Available In the recent past, a great number of e-learning platforms have been introduced on the market showing different characteristics and services. These platforms can be evaluated using multiple criteria and methods. This paper proposes a list of selected quality criteria for describing, characterizing and selecting e-learning platform. These criteria were designed based on e-learning standards. I also propose a mathematical model to determine the probability that a student uses an e-learning platform based on the factors (criteria that determine the quality of the platform and the socio-demographic variables of the student. The case study presented is an application of the model and the input data, intermediate calculations and final results were processed using SAS (Statistical Analysis Software.

  12. Synthesis, antimicrobial evaluation and QSAR studies of propionic acid derivatives

    Directory of Open Access Journals (Sweden)

    Sanjiv Kumar

    2017-02-01

    Full Text Available A series of Schiff bases (1–17 and esters (18–24 of propionic acid was synthesized in appreciable yield and characterized by physicochemical as well as spectral means. The synthesized compounds were evaluated in vitro for their antimicrobial activity against Gram-positive bacteria Staphylococcus aureus, Bacillus subtilis, Gram negative bacterium Escherichia coli and fungal strains Candida albicans and Aspergillus niger by tube dilution method. Results of antimicrobial screening indicated that besides having good antibacterial activity, the synthesized compounds also displayed appreciable antifungal activity and compound 10 emerged as the most active antifungal agent (pMICca and pMICan = 1.93. The results of QSAR studies demonstrated that antibacterial, antifungal and overall antimicrobial activities of synthesized propionic acid derivatives were governed by the topological parameters, Kier’s alpha first order shape index (κα1 and valence first order molecular connectivity index (1χv.

  13. Study on ductile fracture evaluation for austenitic stainless steel

    International Nuclear Information System (INIS)

    Miura, Naoki; Shimakawa, Takashi; Kashima, Koichi; Michiba, Kouji; Hiramatsu, Hideki.

    1994-01-01

    In the development of Fast Breeder Reactors (FBRs), structural integrity must be assured for components subjected to high temperatures up to 550degC, even though possible defects are