Principal Hawaiian Islands Geoid Heights (GEOID96)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This 2' geoid height grid for the Principal Hawaiian Islands is distributed as a GEOID96 model. The computation used 61,000 terrestrial and marine gravity data held...

Airborne geoid determination

DEFF Research Database (Denmark)

Forsberg, René; Olesen, Arne Vestergaard; Bastos, L.

2000-01-01

Airborne geoid mapping techniques may provide the opportunity to improve the geoid over vast areas of the Earth, such as polar areas, tropical jungles and mountainous areas, and provide an accurate "seam-less" geoid model across most coastal regions. Determination of the geoid by airborne methods...... relies on the development of airborne gravimetry, which in turn is dependent on developments in kinematic GPS. Routine accuracy of airborne gravimetry are now at the 2 mGal level, which may translate into 5-10 cm geoid accuracy on regional scales. The error behaviour of airborne gravimetry is well......-suited for geoid determination, with high-frequency survey and downward continuation noise being offset by the low-pass gravity to geoid filtering operation. In the paper the basic principles of airborne geoid determination are outlined, and examples of results of recent airborne gravity and geoid surveys...

Geoid undulation accuracy

Science.gov (United States)

Rapp, Richard H.

1993-01-01

The determination of the geoid and equipotential surface of the Earth's gravity field, has long been of interest to geodesists and oceanographers. The geoid provides a surface to which the actual ocean surface can be compared with the differences implying information on the circulation patterns of the oceans. For use in oceanographic applications the geoid is ideally needed to a high accuracy and to a high resolution. There are applications that require geoid undulation information to an accuracy of +/- 10 cm with a resolution of 50 km. We are far from this goal today but substantial improvement in geoid determination has been made. In 1979 the cumulative geoid undulation error to spherical harmonic degree 20 was +/- 1.4 m for the GEM10 potential coefficient model. Today the corresponding value has been reduced to +/- 25 cm for GEM-T3 or +/- 11 cm for the OSU91A model. Similar improvements are noted by harmonic degree (wave-length) and in resolution. Potential coefficient models now exist to degree 360 based on a combination of data types. This paper discusses the accuracy changes that have taken place in the past 12 years in the determination of geoid undulations.

GRAVTool, a Package to Compute Geoid Model by Remove-Compute-Restore Technique

Science.gov (United States)

Marotta, G. S.; Blitzkow, D.; Vidotti, R. M.

2015-12-01

Currently, there are several methods to determine geoid models. They can be based on terrestrial gravity data, geopotential coefficients, astro-geodetic data or a combination of them. Among the techniques to compute a precise geoid model, the Remove-Compute-Restore (RCR) has been widely applied. It considers short, medium and long wavelengths derived from altitude data provided by Digital Terrain Models (DTM), terrestrial gravity data and global geopotential coefficients, respectively. In order to apply this technique, it is necessary to create procedures that compute gravity anomalies and geoid models, by the integration of different wavelengths, and that adjust these models to one local vertical datum. This research presents a developed package called GRAVTool based on MATLAB software to compute local geoid models by RCR technique and its application in a study area. The studied area comprehends the federal district of Brazil, with ~6000 km², wavy relief, heights varying from 600 m to 1340 m, located between the coordinates 48.25ºW, 15.45ºS and 47.33ºW, 16.06ºS. The results of the numerical example on the studied area show the local geoid model computed by the GRAVTool package (Figure), using 1377 terrestrial gravity data, SRTM data with 3 arc second of resolution, and geopotential coefficients of the EIGEN-6C4 model to degree 360. The accuracy of the computed model (σ = ± 0.071 m, RMS = 0.069 m, maximum = 0.178 m and minimum = -0.123 m) matches the uncertainty (σ =± 0.073) of 21 points randomly spaced where the geoid was computed by geometrical leveling technique supported by positioning GNSS. The results were also better than those achieved by Brazilian official regional geoid model (σ = ± 0.099 m, RMS = 0.208 m, maximum = 0.419 m and minimum = -0.040 m).

Gravity model improvement investigation. [improved gravity model for determination of ocean geoid

Science.gov (United States)

Siry, J. W.; Kahn, W. D.; Bryan, J. W.; Vonbun, F. F.

1973-01-01

This investigation was undertaken to improve the gravity model and hence the ocean geoid. A specific objective is the determination of the gravity field and geoid with a space resolution of approximately 5 deg and a height resolution of the order of five meters. The concept of the investigation is to utilize both GEOS-C altimeter and satellite-to-satellite tracking data to achieve the gravity model improvement. It is also planned to determine the geoid in selected regions with a space resolution of about a degree and a height resolution of the order of a meter or two. The short term objectives include the study of the gravity field in the GEOS-C calibration area outlined by Goddard, Bermuda, Antigua, and Cape Kennedy, and also in the eastern Pacific area which is viewed by ATS-F.

Investigating the Indian Ocean Geoid Low

Science.gov (United States)

Ghosh, A.; Gollapalli, T.; Steinberger, B. M.

2016-12-01

The lowest geoid anomaly on Earth lies in the Indian Ocean just south of the Indian peninsula.Several theories have been proposed to explain this geoid low, most of which invoke past subduction. Some recent studies have alsoargued that high velocity anomalies in the lower mantle coupled with low velocity anomalies in the upper mantle are responsible for these negative geoidanomalies. However, there is no general consensus regarding the source of the Indian Ocean negative geoid. We investigate the source of this geoid low by using forward models of density driven mantle convection using CitcomS. We test various tomography models in our flow calculations with different radial and lateral viscosity variations. Many tomography modelsproduce a fairly high correlation to the global geoid, however none could match the precise location of the geoid low in the Indian Ocean. Amerged P-wave model of LLNL-G3DV3 in the Indian Ocean region and S40rts elsewhere yields a good fit to the geoid anomaly, both in pattern and magnitude.The source of this geoid low seems to stem from a low velocity anomaly stretching from a depth of 300 km up to 700 km in the northern Indian Ocean region.This velocity anomaly could potentially arise from material rising along the edge of the African LLSVP and moving towards the northeast, facilitated by the movementof the Indian plate in the same direction.

Learning-based computing techniques in geoid modeling for precise height transformation

Science.gov (United States)

Erol, B.; Erol, S.

2013-03-01

Precise determination of local geoid is of particular importance for establishing height control in geodetic GNSS applications, since the classical leveling technique is too laborious. A geoid model can be accurately obtained employing properly distributed benchmarks having GNSS and leveling observations using an appropriate computing algorithm. Besides the classical multivariable polynomial regression equations (MPRE), this study attempts an evaluation of learning based computing algorithms: artificial neural networks (ANNs), adaptive network-based fuzzy inference system (ANFIS) and especially the wavelet neural networks (WNNs) approach in geoid surface approximation. These algorithms were developed parallel to advances in computer technologies and recently have been used for solving complex nonlinear problems of many applications. However, they are rather new in dealing with precise modeling problem of the Earth gravity field. In the scope of the study, these methods were applied to Istanbul GPS Triangulation Network data. The performances of the methods were assessed considering the validation results of the geoid models at the observation points. In conclusion the ANFIS and WNN revealed higher prediction accuracies compared to ANN and MPRE methods. Beside the prediction capabilities, these methods were also compared and discussed from the practical point of view in conclusions.

Mexico Geoid Heights (MEXICO97)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This 2' geoid height grid for Mexico, and North-Central America, is the MEXICO97 geoid model. The computation used about one million terrestrial and marine gravity...

ERRORS MEASUREMENT OF INTERPOLATION METHODS FOR GEOID MODELS: STUDY CASE IN THE BRAZILIAN REGION

Directory of Open Access Journals (Sweden)

Daniel Arana

Full Text Available Abstract: The geoid is an equipotential surface regarded as the altimetric reference for geodetic surveys and it therefore, has several practical applications for engineers. In recent decades the geodetic community has concentrated efforts on the development of highly accurate geoid models through modern techniques. These models are supplied through regular grids which users need to make interpolations. Yet, little information can be obtained regarding the most appropriate interpolation method to extract information from the regular grid of geoidal models. The use of an interpolator that does not represent the geoid surface appropriately can impair the quality of geoid undulations and consequently the height transformation. This work aims to quantify the magnitude of error that comes from a regular mesh of geoid models. The analysis consisted of performing a comparison between the interpolation of the MAPGEO2015 program and three interpolation methods: bilinear, cubic spline and neural networks Radial Basis Function. As a result of the experiments, it was concluded that 2.5 cm of the 18 cm error of the MAPGEO2015 validation is caused by the use of interpolations in the 5'x5' grid.

Spatial uncertainty of a geoid undulation model in Guayaquil, Ecuador

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Chicaiza E.G.

2017-06-01

Full Text Available Geostatistics is a discipline that deals with the statistical analysis of regionalized variables. In this case study, geostatistics is used to estimate geoid undulation in the rural area of Guayaquil town in Ecuador. The geostatistical approach was chosen because the estimation error of prediction map is getting. Open source statistical software R and mainly geoR, gstat and RGeostats libraries were used. Exploratory data analysis (EDA, trend and structural analysis were carried out. An automatic model fitting by Iterative Least Squares and other fitting procedures were employed to fit the variogram. Finally, Kriging using gravity anomaly of Bouguer as external drift and Universal Kriging were used to get a detailed map of geoid undulation. The estimation uncertainty was reached in the interval [-0.5; +0.5] m for errors and a maximum estimation standard deviation of 2 mm in relation with the method of interpolation applied. The error distribution of the geoid undulation map obtained in this study provides a better result than Earth gravitational models publicly available for the study area according the comparison with independent validation points. The main goal of this paper is to confirm the feasibility to use geoid undulations from Global Navigation Satellite Systems and leveling field measurements and geostatistical techniques methods in order to use them in high-accuracy engineering projects.

Spatial uncertainty of a geoid undulation model in Guayaquil, Ecuador

Science.gov (United States)

Chicaiza, E. G.; Leiva, C. A.; Arranz, J. J.; Buenańo, X. E.

2017-06-01

Geostatistics is a discipline that deals with the statistical analysis of regionalized variables. In this case study, geostatistics is used to estimate geoid undulation in the rural area of Guayaquil town in Ecuador. The geostatistical approach was chosen because the estimation error of prediction map is getting. Open source statistical software R and mainly geoR, gstat and RGeostats libraries were used. Exploratory data analysis (EDA), trend and structural analysis were carried out. An automatic model fitting by Iterative Least Squares and other fitting procedures were employed to fit the variogram. Finally, Kriging using gravity anomaly of Bouguer as external drift and Universal Kriging were used to get a detailed map of geoid undulation. The estimation uncertainty was reached in the interval [-0.5; +0.5] m for errors and a maximum estimation standard deviation of 2 mm in relation with the method of interpolation applied. The error distribution of the geoid undulation map obtained in this study provides a better result than Earth gravitational models publicly available for the study area according the comparison with independent validation points. The main goal of this paper is to confirm the feasibility to use geoid undulations from Global Navigation Satellite Systems and leveling field measurements and geostatistical techniques methods in order to use them in high-accuracy engineering projects.

Marine Geoid Undulation Assessment Over South China Sea Using Global Geopotential Models and Airborne Gravity Data

Science.gov (United States)

Yazid, N. M.; Din, A. H. M.; Omar, K. M.; Som, Z. A. M.; Omar, A. H.; Yahaya, N. A. Z.; Tugi, A.

2016-09-01

Global geopotential models (GGMs) are vital in computing global geoid undulations heights. Based on the ellipsoidal height by Global Navigation Satellite System (GNSS) observations, the accurate orthometric height can be calculated by adding precise and accurate geoid undulations model information. However, GGMs also provide data from the satellite gravity missions such as GRACE, GOCE and CHAMP. Thus, this will assist to enhance the global geoid undulations data. A statistical assessment has been made between geoid undulations derived from 4 GGMs and the airborne gravity data provided by Department of Survey and Mapping Malaysia (DSMM). The goal of this study is the selection of the best possible GGM that best matches statistically with the geoid undulations of airborne gravity data under the Marine Geodetic Infrastructures in Malaysian Waters (MAGIC) Project over marine areas in Sabah. The correlation coefficients and the RMS value for the geoid undulations of GGM and airborne gravity data were computed. The correlation coefficients between EGM 2008 and airborne gravity data is 1 while RMS value is 0.1499.In this study, the RMS value of EGM 2008 is the lowest among the others. Regarding to the statistical analysis, it clearly represents that EGM 2008 is the best fit for marine geoid undulations throughout South China Sea.

Estimating Gravity Biases with Wavelets in Support of a 1-cm Accurate Geoid Model

Science.gov (United States)

Ahlgren, K.; Li, X.

2017-12-01

Systematic errors that reside in surface gravity datasets are one of the major hurdles in constructing a high-accuracy geoid model at high resolutions. The National Oceanic and Atmospheric Administration's (NOAA) National Geodetic Survey (NGS) has an extensive historical surface gravity dataset consisting of approximately 10 million gravity points that are known to have systematic biases at the mGal level (Saleh et al. 2013). As most relevant metadata is absent, estimating and removing these errors to be consistent with a global geopotential model and airborne data in the corresponding wavelength is quite a difficult endeavor. However, this is crucial to support a 1-cm accurate geoid model for the United States. With recently available independent gravity information from GRACE/GOCE and airborne gravity from the NGS Gravity for the Redefinition of the American Vertical Datum (GRAV-D) project, several different methods of bias estimation are investigated which utilize radial basis functions and wavelet decomposition. We estimate a surface gravity value by incorporating a satellite gravity model, airborne gravity data, and forward-modeled topography at wavelet levels according to each dataset's spatial wavelength. Considering the estimated gravity values over an entire gravity survey, an estimate of the bias and/or correction for the entire survey can be found and applied. In order to assess the accuracy of each bias estimation method, two techniques are used. First, each bias estimation method is used to predict the bias for two high-quality (unbiased and high accuracy) geoid slope validation surveys (GSVS) (Smith et al. 2013 & Wang et al. 2017). Since these surveys are unbiased, the various bias estimation methods should reflect that and provide an absolute accuracy metric for each of the bias estimation methods. Secondly, the corrected gravity datasets from each of the bias estimation methods are used to build a geoid model. The accuracy of each geoid model

U.S. Geoid Heights, Scientific Model (G96SSS)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This 2' geoid height grid for the conterminous United States is the G96SSS model. The computation used about 1.8 million terrestrial and marine gravity data held in...

Geoid Height and Deflections of the Vertical Models - National Geospatial Data Asset (NGDA) Geoid Models

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — In Gauss' words, the geoid is "the mathematical figure of the Earth". This figure is an equipotential surface coincident with the idealized mean sea surface. The...

Assessment of Gravity Field and Steady State Ocean Circulation Explorer (GOCE) geoid model using GPS levelling over Sabah and Sarawak

Science.gov (United States)

Othman, A. H.; Omar, K. M.; Din, A. H. M.; Som, Z. A. M.; Yahaya, N. A. Z.; Pa'suya, M. F.

2016-06-01

The GOCE satellite mission has significantly contributed to various applications such as solid earth physics, oceanography and geodesy. Some substantial applications of geodesy are to improve the gravity field knowledge and the precise geoid modelling towards realising global height unification. This paper aims to evaluate GOCE geoid model based on the recent GOCE Global Geopotential Model (GGM), as well as EGM2008, using GPS levelling data over East Malaysia, i.e. Sabah and Sarawak. The satellite GGMs selected in this study are the GOCE GGM models which include GOCE04S, TIM_R5 and SPW_R4, and the EGM2008 model. To assess these models, the geoid heights from these GGMs are compared to the local geometric geoid height. The GGM geoid heights was derived using EGMLAB1 software and the geometric geoid height was computed by available GPS levelling information obtained from the Department Survey and Mapping Malaysia. Generally, the GOCE models performed better than EGM2008 over East Malaysia and the best fit GOCE model for this region is the TIM_R5 model. The TIM_R5 GOCE model demonstrated the lowest R.M.S. of ± 16.5 cm over Sarawak, comparatively. For further improvement, this model should be combined with the local gravity data for optimum geoid modelling over East Malaysia.

Practical application of the geometric geoid for heighting over ...

African Journals Online (AJOL)

This is because a geoid model is required to convert ellipsoidal heights to orthometric heights that are used in practice. A local geometric geoid ... The geoid height is expressed as a function of the local plane coordinates through a biquadratic surface polynomial, using 14 GPS/levelling points. Five points have been used ...

How to handle topography in practical geoid determination: three examples

DEFF Research Database (Denmark)

Omang, O.C.D.; Forsberg, René

2000-01-01

Three different methods of handling topography in geoid determination were investigated. The first two methods employ the residual terrain model (RTM) remove-restore technique, yielding the quasi-geoid, whereas the third method uses the classical Helmert condensation method, yielding the geoid. All...

Refining geoid and vertical gradient of gravity anomaly

Directory of Open Access Journals (Sweden)

Zhang Chijun

2011-11-01

Full Text Available We have derived and tested several relations between geoid (N and quasi-geoid (ζ with model validation. The elevation correction consists of the first-term (Bouguer anomaly and second-term (vertical gradient of gravity anomaly. The vertical gradient was obtained from direct measurement and terrain calculation. The test results demonstrated that the precision of geoid can reach centimeter-level in mountains less than 5000 meters high.

GRAVTool, Advances on the Package to Compute Geoid Model path by the Remove-Compute-Restore Technique, Following Helmert's Condensation Method

Science.gov (United States)

Marotta, G. S.

2017-12-01

Currently, there are several methods to determine geoid models. They can be based on terrestrial gravity data, geopotential coefficients, astrogeodetic data or a combination of them. Among the techniques to compute a precise geoid model, the Remove Compute Restore (RCR) has been widely applied. It considers short, medium and long wavelengths derived from altitude data provided by Digital Terrain Models (DTM), terrestrial gravity data and Global Geopotential Model (GGM), respectively. In order to apply this technique, it is necessary to create procedures that compute gravity anomalies and geoid models, by the integration of different wavelengths, and adjust these models to one local vertical datum. This research presents the advances on the package called GRAVTool to compute geoid models path by the RCR, following Helmert's condensation method, and its application in a study area. The studied area comprehends the federal district of Brazil, with 6000 km², wavy relief, heights varying from 600 m to 1340 m, located between the coordinates 48.25ºW, 15.45ºS and 47.33ºW, 16.06ºS. The results of the numerical example on the studied area show a geoid model computed by the GRAVTool package, after analysis of the density, DTM and GGM values, more adequate to the reference values used on the study area. The accuracy of the computed model (σ = ± 0.058 m, RMS = 0.067 m, maximum = 0.124 m and minimum = -0.155 m), using density value of 2.702 g/cm³ ±0.024 g/cm³, DTM SRTM Void Filled 3 arc-second and GGM EIGEN-6C4 up to degree and order 250, matches the uncertainty (σ =± 0.073) of 26 points randomly spaced where the geoid was computed by geometrical leveling technique supported by positioning GNSS. The results were also better than those achieved by Brazilian official regional geoid model (σ = ± 0.076 m, RMS = 0.098 m, maximum = 0.320 m and minimum = -0.061 m).

An ocean modelling and assimilation guide to using GOCE geoid products

DEFF Research Database (Denmark)

Haines, K.; Johannessen, J. A.; Knudsen, Per

2011-01-01

We review the procedures and challenges that must be considered when using geoid data derived from the Gravity and steady-state Ocean Circulation Explorer (GOCE) mission in order to constrain the circulation and water mass representation in an ocean general circulation model. It covers the combin...

Rigorous covariance propagation of geoid errors to geodetic MDT estimates

Science.gov (United States)

Pail, R.; Albertella, A.; Fecher, T.; Savcenko, R.

2012-04-01

The mean dynamic topography (MDT) is defined as the difference between the mean sea surface (MSS) derived from satellite altimetry, averaged over several years, and the static geoid. Assuming geostrophic conditions, from the MDT the ocean surface velocities as important component of global ocean circulation can be derived from it. Due to the availability of GOCE gravity field models, for the very first time MDT can now be derived solely from satellite observations (altimetry and gravity) down to spatial length-scales of 100 km and even below. Global gravity field models, parameterized in terms of spherical harmonic coefficients, are complemented by the full variance-covariance matrix (VCM). Therefore, for the geoid component a realistic statistical error estimate is available, while the error description of the altimetric component is still an open issue and is, if at all, attacked empirically. In this study we make the attempt to perform, based on the full gravity VCM, rigorous error propagation to derived geostrophic surface velocities, thus also considering all correlations. For the definition of the static geoid we use the third release of the time-wise GOCE model, as well as the satellite-only combination model GOCO03S. In detail, we will investigate the velocity errors resulting from the geoid component in dependence of the harmonic degree, and the impact of using/no using covariances on the MDT errors and its correlations. When deriving an MDT, it is spectrally filtered to a certain maximum degree, which is usually driven by the signal content of the geoid model, by applying isotropic or non-isotropic filters. Since this filtering is acting also on the geoid component, the consistent integration of this filter process into the covariance propagation shall be performed, and its impact shall be quantified. The study will be performed for MDT estimates in specific test areas of particular oceanographic interest.

Using GPS and leveling data in local precise geoid determination and case study

Science.gov (United States)

Erol, B.; Çelik, R. N.; Erol, S.

2003-04-01

the fundamental mathematical equation; N=h-H. In the equation, "h" is the ellipsoidal height of a point P, "H" is the orthometric height of the same point and "N" is "geoid undulation" value. Normally, "H" orthometric height derived from leveling measurements but these measurements are tiring applications. So, while having a geoid model in the region as the essential part of geodetic infrastructure, number leveling measurements can be reduced from the procedure and by this way time and labor is saved. Geoid determination is modeling of the data in such a way that geoid height can be obtained digital or analog at a point whose horizontal position is known. Geoid models can be developed for local, regional or global regions. Using satellite techniques, especially GPS, in geodetic measurements are increased importance of geoid. Because geoid is a natural tie between high precision geodetic coordinates and coordinates which obtained from satellites. There are several geoid determination methods according to used data and models. GPS/Leveling method, which is also known as geometric method, is one of these methods. This method is appropriate for local precise geoid determination in respectively small areas. In this paper, it is going to be given information about GPS/Leveling geoid determination method and mathematical models, which are used in geoid determination with this method. And Izmir local geoid model will be presented as a case study. Izmir is one of the west metropolitan cities of Turkey and located near Aegean Sea. The topography is extremely rough in the region. There are two different geoid determination studies which were carried out in 1996 and 2001 in Izmir. Both models were accomplished according to GPS/Leveling method. Those two geoid models of Izmir Metropolitan region are investigated in here, the conflict of them were discussed. The relation between distribution of common reference points and differences of geoid undulation values, which are calculated

Alaska/Yukon Geoid Improvement by a Data-Driven Stokes's Kernel Modification Approach

Science.gov (United States)

Li, Xiaopeng; Roman, Daniel R.

2015-04-01

Geoid modeling over Alaska of USA and Yukon Canada being a trans-national issue faces a great challenge primarily due to the inhomogeneous surface gravity data (Saleh et al, 2013) and the dynamic geology (Freymueller et al, 2008) as well as its complex geological rheology. Previous study (Roman and Li 2014) used updated satellite models (Bruinsma et al 2013) and newly acquired aerogravity data from the GRAV-D project (Smith 2007) to capture the gravity field changes in the targeting areas primarily in the middle-to-long wavelength. In CONUS, the geoid model was largely improved. However, the precision of the resulted geoid model in Alaska was still in the decimeter level, 19cm at the 32 tide bench marks and 24cm on the 202 GPS/Leveling bench marks that gives a total of 23.8cm at all of these calibrated surface control points, where the datum bias was removed. Conventional kernel modification methods in this area (Li and Wang 2011) had limited effects on improving the precision of the geoid models. To compensate the geoid miss fits, a new Stokes's kernel modification method based on a data-driven technique is presented in this study. First, the method was tested on simulated data sets (Fig. 1), where the geoid errors have been reduced by 2 orders of magnitude (Fig 2). For the real data sets, some iteration steps are required to overcome the rank deficiency problem caused by the limited control data that are irregularly distributed in the target area. For instance, after 3 iterations, the standard deviation dropped about 2.7cm (Fig 3). Modification at other critical degrees can further minimize the geoid model miss fits caused either by the gravity error or the remaining datum error in the control points.

Subducted slabs and lateral viscosity variations: effects on the long-wavelength geoid

Science.gov (United States)

Tosi, Nicola; Čadek, Ondřej; Martinec, Zdeněk

2009-11-01

The characteristic broad local maxima exhibited by the long-wavelength geoid over subduction zones are investigated with a numerical model of mantle flow. In a spherical axisymmetric geometry, a synthetic model of buoyancy driven subduction is used to test the effects on the geoid caused by the depth of penetration of the lithosphere into the mantle, by the viscosity stratification and by lateral viscosity variations (LVV) in the lithosphere, upper and lower mantle. The presence of anomalous slab density in the lower mantle guarantees geoid amplitudes comparable with the observations, favouring the picture of slabs that penetrate the transition zone and sink into the deep mantle. The viscosity of the lower mantle controls the long-wavelength geoid to the first order, ensuring a clear positive signal when it is at least 30-times greater than the upper-mantle viscosity. The presence of LVV in the lithosphere, in the form of weak plate margins, helps to increase the contribution of the surface topography, causing a pronounced reduction of the geoid. Localized LVV associated with the cold slab play a secondary role if they are in the upper mantle. On the other hand, highly viscous slabs in the lower mantle exert a large influence on the geoid. They cause its amplitude to increase dramatically, way beyond the values typically observed over subduction zones. Long-wavelength flow becomes less vigorous as the slab viscosity increases. Deformation in the upper mantle becomes more localized and power is transferred to short wavelengths, causing the long-wavelength surface topography to diminish and the total geoid to increase. Slabs may be then weakened in the lower mantle or retain their high viscosity while other mechanisms act to lower the geoid. It is shown that a phase change from perovskite to post-perovskite above the core-mantle boundary can cause the geoid to reduce significantly, thereby helping to reconcile models and observations.

Deep structure of the Tristan-Gough plume revealed by geoid anomalies

Science.gov (United States)

Maia, M.; Flamme, J.; Cadio, C.; Lalancette, M. F.; Metivier, L.; Pajot-Métivier, G.; Diament, M.

2017-12-01

The origin of the hotspot Tristan da Cunha located at the southwestern end of Walvis Ridge in the Atlantic Ocean is still a controversial topic. We especially question on the nature of the involved geodynamical processes and on their origin depth. The latest results based on local seismic and magnetic data (Schlömer et al., 2016; Baba et al., 2016; Geissler et al., 2016) suggest the existence of a plume coming from the mid-mantle in the southwest of the archipelago. Here we give a regional view of mantle dynamics patterns in the area by using the high-quality satellite geoid data. To extract the mantle signature, we estimate the crustal and lithospheric signals of the ocean basin and South American and African continents, which contribute to mid- and long-wavelengths in the total geoid. We pay particular attention to the modeling of continental margins and their effects on the residual geoid signal. In addition, we explore a large density values set derived from petrological and geochemical studies in the calculation of the lithospheric geoid model. After subtracting the lithospheric signature to the EGM2008 geoid, we apply a multi-scale analysis, which unfolds the different components of the geoid residual signal. The analysis underlines a set of positive anomalies at 200-400 km in the study area, notably in north and west of Tristan de Cunha, and a positive anomaly at 700-1100 km scale in the southwest of the archipelago. These patterns do not change by using different lithospheric geoid models, which allow us to evaluate the reliability of the residual geoid anomalies. These results indicate the existence of small-scale density anomalies in the upper mantle and a larger scale density anomaly in the mid-mantle. Our study suggests that a large dome toped by plume clusters could be a good candidate to explain the volcanism of Tristan da Cunha.Schlömer et al., 2016 Hunting for the Tristan mantle plume..., EPSL, http://dx.doi.org/10.1016/j.epsl.2016.12.028Baba et

Use of GOCE L2 Gravity Gradients for full resolution Geoid

DEFF Research Database (Denmark)

Herceg, Matija; Tscherning, Carl Christian; Knudsen, Per

The objective of this study is to develop methodology to use GOCE gravity gradients for enhanced geoid modelling and ocean circulation modelling. In specific regions with a rough gravity field, the resolution of the geoid may be enhanced substantially if GOCE gradiometer data are used in addition...... of the GOCE spherical harmonic coefficient model (EGMs) since in such areas the GOCE gradients contain more information than the EGM itself. Hence, the use of gradients may lead to improve the resolution of e.g. the marine geoid which in turn will improve the estimation of the ocean circulation....... This is tested using GOCE gravity gradient data, the GEOCOL program (GRAVSOFT) and Reduced Point Mass (RPM) program. Tests are carried out in the GOCINA region and in the Mediterranean basin. Furthermore, the effect of the decreasing height of the GOCE satellite on gravity gradients and associated MDT...

Towards the Selection of an Optimal Global Geopotential Model for the Computation of the Long-Wavelength Contribution: A Case Study of Ghana

Directory of Open Access Journals (Sweden)

Caleb Iddissah Yakubu

2017-11-01

Full Text Available The selection of a global geopotential model (GGM for modeling the long-wavelength for geoid computation is imperative not only because of the plethora of GGMs available but more importantly because it influences the accuracy of a geoid model. In this study, we propose using the Gaussian averaging function for selecting an optimal GGM and degree and order (d/o for the remove-compute-restore technique as a replacement for the direct comparison of terrestrial gravity anomalies and GGM anomalies, because ground data and GGM have different frequencies. Overall, EGM2008 performed better than all the tested GGMs and at an optimal d/o of 222. We verified the results by computing geoid models using Heck and Grüninger’s modification and validated them against GPS/trigonometric data. The results of the validation were consistent with those of the averaging process with EGM2008 giving the smallest standard deviation of 0.457 m at d/o 222, resulting in an 8% improvement over the previous geoid model. In addition, this geoid model, the Ghanaian Gravimetric Geoid 2017 (GGG 2017 may be used to replace second-order class II leveling, with an expected error of 6.8 mm/km for baselines ranging from 20 to 225 km.

Simultaneous solution of the geoid and the surface density anomalies

Science.gov (United States)

Ardalan, A. A.; Safari, A.; Karimi, R.; AllahTavakoli, Y.

2012-04-01

The main application of the land gravity data in geodesy is "local geoid" or "local gravity field" modeling, whereas the same data could play a vital role for the anomalous mass-density modeling in geophysical explorations. In the realm of local geoid computations based on Geodetic Boundary Value Problems (GBVP), it is needed that the effect of the topographic (or residual terrain) masses be removed via application of the Newton integral in order to perform the downward continuation in a harmonic space. However, harmonization of the downward continuation domain may not be perfectly possible unless accurate information about the mass-density of the topographic masses be available. On the other hand, from the exploration point of view the unwanted topographical masses within the aforementioned procedure could be regarded as the signal. In order to overcome the effect of the remaining masses within the remove step of the GBVP, which cause uncertainties in mathematical modeling of the problem, here we are proposing a methodology for simultaneous solution of the geoid and residual surface density modeling In other words, a new mathematical model will be offered which both provides the needed harmonic space for downward continuation and at the same time accounts for the non-harmonic terms of gravitational field and makes use of it for residual mass density modeling within the topographic region. The presented new model enjoys from uniqueness of the solution, opposite to the inverse application of the Newton integral for mass density modeling which is non-unique, and only needs regularization to remove its instability problem. In this way, the solution of the model provides both the incremental harmonic gravitational potential on surface of the reference ellipsoid as the gravity field model and the lateral surface mass-density variations via the second derivatives of the non harmonic terms of gravitational field. As the case study and accuracy verification, the proposed

Direct regional quasi-geoid determination using EGM2008 and DEM: A case study for Mainland China and its vicinity areas

Directory of Open Access Journals (Sweden)

Jin Li

2015-11-01

Full Text Available Earth's gravity model (EGM helps people better determine the figure of Earth, which is generally represented by a global geoid. For a considerable amount of practical applications, people use quasi-geoid to approximate the geoid, thus the quasi-geoid is also treated as an important height datum. In this study we revisit the method to directly determine regional quasi-geoid using EGM and digital elevation model (DEM, on the basis of Molodensky theory. According to the method we obtain a 5′ × 5′ quasi-geoid for Mainland China and its vicinity areas, based on the EGM2008 gravitational potential model and the Shuttle Radar Topography Mission (SRTM DEM model. By comparing height anomalies derived from EGM2008 with observations at 70 GPS/leveling points in areas including northwest, mid-west, mid-east and southeast of China, we find that the 5′ × 5′ EGM2008 quasi-geoid well fits the GPS/leveling results, with average deviations less than 10 cm for the selected areas in east China (with mainly plain topography and ∼20 cm for the selected areas in west China (highland or mountainous areas. We also discuss a few technical issues for directly determining height anomalies based on EGM and DEM, under the frame of Molodensky theory.

Airborne gravimetry for geoid and GOCE

DEFF Research Database (Denmark)

Forsberg, R.; Olesen, A. V.; Nielsen, E.

2014-01-01

DTU-Space has since 1996 carried out large area airborne surveys over both polar, tropical and temperate regions, especially for geoid determination and global geopotential models. Recently we have started flying two gravimeters (LCR and Chekan-AM) side by side for increased reliability and redun......DTU-Space has since 1996 carried out large area airborne surveys over both polar, tropical and temperate regions, especially for geoid determination and global geopotential models. Recently we have started flying two gravimeters (LCR and Chekan-AM) side by side for increased reliability...... in Antarctica and Tanzania based on DTU-Space aerogravity and GOCE. In both cases the airborne data validate GOCE to very high degrees, and confirms the synergy of airborne gravity and GOCE. For Antarctica, the deep interior Antarctic survey (continued in 2013 from a remote field camp), shows...... that it is possible efficiently to cover even the most remote regions on the planet with good aerogravity. With the recent termination of the GOCE mission, it is therefore timely to initiate a coordinated, preferably international, airborne gravity effort to cover the polar gap south of 83° S; such a survey can...

Oceanic Geoid and Tides Obtained from GEOS-3 Satellite Data in the Northwestern Atlantic Ocean

Science.gov (United States)

Won, I. J.; Miller, L. S.

1978-01-01

Two sets of GEO-3 altimeter data which fall within about a 2.5 degree width are analyzed for ocean geoid and tides. One set covers a linear path from Newfoundland to Cuba and the other from Puerto Rico to the North Carolina coast. Forty different analyses using various parameters are performed in order to investigate convergence. Profiles of the geoid and four tides, M sub 2 O sub 1, S sub 2, and K sub 1, are obtained along the two strips. The results demonstrate convergent solutions for all forty cases and show, within expectation, fair agreement with those obtained from the MODE deep-sea tide gauge. It is also shown that the oceanic geoid obtained through this analysis can potentially improve the short wavelength structure over existing geoid models.

Towards an exact relativistic theory of Earth's geoid undulation

International Nuclear Information System (INIS)

Kopeikin, Sergei M.; Mazurova, Elena M.; Karpik, Alexander P.

2015-01-01

The present paper extends the Newtonian concept of the geoid in classic geodesy towards the realm of general relativity by utilizing the covariant geometric methods of the perturbation theory of curved manifolds. It yields a covariant definition of the anomalous (disturbing) gravity potential and formulates differential equation for it in the form of a covariant Laplace equation. The paper also derives the Bruns equation for calculation of geoid's height with full account for relativistic effects beyond the Newtonian approximation. A brief discussion of the relativistic Bruns formula is provided. - Highlights: • We apply general relativity to define the exact concept of relativistic geoid. • We derive relativistic equation of geoid and the reference level surface. • We employ the manifold perturbation theory to discuss geoid's undulation

Towards an exact relativistic theory of Earth's geoid undulation

Energy Technology Data Exchange (ETDEWEB)

Kopeikin, Sergei M., E-mail: kopeikins@missouri.edu [Department of Physics & Astronomy, University of Missouri, Columbia, MO 65211 (United States); Siberian State Geodetic Academy, 10 Plakhotny St., Novosibirsk 630108 (Russian Federation); Mazurova, Elena M., E-mail: e_mazurova@mail.ru [Moscow State University of Geodesy and Cartography, 4 Gorokhovsky Alley, Moscow 105064 (Russian Federation); Siberian State Geodetic Academy, 10 Plakhotny St., Novosibirsk 630108 (Russian Federation); Karpik, Alexander P., E-mail: rector@ssga.ru [Siberian State Geodetic Academy, 10 Plakhotny St., Novosibirsk 630108 (Russian Federation)

2015-08-14

The present paper extends the Newtonian concept of the geoid in classic geodesy towards the realm of general relativity by utilizing the covariant geometric methods of the perturbation theory of curved manifolds. It yields a covariant definition of the anomalous (disturbing) gravity potential and formulates differential equation for it in the form of a covariant Laplace equation. The paper also derives the Bruns equation for calculation of geoid's height with full account for relativistic effects beyond the Newtonian approximation. A brief discussion of the relativistic Bruns formula is provided. - Highlights: • We apply general relativity to define the exact concept of relativistic geoid. • We derive relativistic equation of geoid and the reference level surface. • We employ the manifold perturbation theory to discuss geoid's undulation.

Reconciling Long-Wavelength Dynamic Topography, Geoid Anomalies and Mass Distribution on Earth

Science.gov (United States)

Hoggard, M.; Richards, F. D.; Ghelichkhan, S.; Austermann, J.; White, N.

2017-12-01

Since the first satellite observations in the late 1950s, we have known that that the Earth's non-hydrostatic geoid is dominated by spherical harmonic degree 2 (wavelengths of 16,000 km). Peak amplitudes are approximately ± 100 m, with highs centred on the Pacific Ocean and Africa, encircled by lows in the vicinity of the Pacific Ring of Fire and at the poles. Initial seismic tomography models revealed that the shear-wave velocity, and therefore presumably the density structure, of the lower mantle is also dominated by degree 2. Anti-correlation of slow, probably low density regions beneath geoid highs indicates that the mantle is affected by large-scale flow. Thus, buoyant features are rising and exert viscous normal stresses that act to deflect the surface and core-mantle boundary (CMB). Pioneering studies in the 1980s showed that a viscosity jump between the upper and lower mantle is required to reconcile these geoid and tomographically inferred density anomalies. These studies also predict 1-2 km of dynamic topography at the surface, dominated by degree 2. In contrast to this prediction, a global observational database of oceanic residual depth measurements indicates that degree 2 dynamic topography has peak amplitudes of only 500 m. Here, we attempt to reconcile observations of dynamic topography, geoid, gravity anomalies and CMB topography using instantaneous flow kernels. We exploit a density structure constructed from blended seismic tomography models, combining deep mantle imaging with higher resolution upper mantle features. Radial viscosity structure is discretised, and we invert for the best-fitting viscosity profile using a conjugate gradient search algorithm, subject to damping. Our results suggest that, due to strong sensitivity to radial viscosity structure, the Earth's geoid seems to be compatible with only ± 500 m of degree 2 dynamic topography.

Inter-comparison of state-of-the-art MSS and geoid models in the Arctic Ocean

DEFF Research Database (Denmark)

Skourup, Henriette; Farrell, Sinead; Hendricks, Stefan

in errors in the estimated freeboard heights, especially in areas with a sparse lead distribution in consolidated ice conditions. Additionally these errors can impact ocean geostrophic current estimates and remaining biases in the models may impact longer-term, multi-sensor oceanographic time-series of sea......State-of-the-art Arctic Ocean mean sea surface (MSS) and geoid models are used to support sea ice freeboard estimation from satellite altimeters, and for oceanographic studies. However, errors in a given model in the high frequency domain, e.g. due to unresolved gravity features, can result...

Improved representations of the Mediterranean Geoid within the GEOMED 2 project. Contributions of local gravity, GOCE and Cryosat2 data

DEFF Research Database (Denmark)

Barzaghi, Riccardo; Vergos, George S.; Albertella, Alberta

The Mediterranean Sea has always been a lab for geosciences, given its geodynamic peculiarities, the large short-scale variations of the gravity field and the complex circulation. Within the GEOMED 2 project, new improved representations of the Mediterranean marine geoid have been deemed...... of a Mediterranean-wide gravity database. The data employed within GEOMED 2 for the determination of the marine geoid are land and marine gravity data, GOCE/GRACE based Global Geopotential Models and a combination of MISTRAL and SRTM/bathymetry terrain models. The processing methodology will be based on the well......)-based techniques have provided the geoid estimation in the frequency domain. In this work, the pre-processing steps consisting in merging and validating all the available gravity observations for the wider Mediterranean are presented and discussed. Furthermore, the latest basin-wide geoid models are estimated from...

The direct effect on geoid computations

OpenAIRE

Juan G. Serpas

2016-01-01

La técnica más popular para la reducción de observaciones gravimétricas al geoide es el método de condensación de Helmert. Dos maneras deferentes de aplicar dicha reducción son estudiadas: el enfoque clásico (Wang y Rapp, 1990, Heiskanen y Morits, 1967) y el enfoque por Vanicek and Kleusberg (1987), extendido por Martinec et al. (1993). El enfoque clásico (Wang y Rapp, 1990, Heiskanen y Moritz, 1967) argumenta que el efecto de la capa condensada tiene que ser evaluado en el geoide y no en el ...

Utilization of high resolution satellite geoid data for estimation of lithospheric thickness in the Bay of Bengal

Digital Repository Service at National Institute of Oceanography (India)

Majumdar, T.J.; Bhattacharyya, R.; Chatterjee, S.; Krishna, K.S.

been estimated using residual geoid data. In a similar fashion, the age offset from the age contours have been observed. (Figs. 5 a and b). Geoid models for ocean ridges and fracture zones If h(t) is the blope is the geoid as a function of seafloor... age, resulting from changes in seafloor depth and plate thickness due to cooling, then the quantity (∆h/age offset) estimated above is simply the derivative of h(t) with respect to age, where t is the mean age between two sides of a fracture8. From...

Airborne gravimetry used in precise geoid computations by ring integration

DEFF Research Database (Denmark)

Kearsley, A.H.W.; Forsberg, René; Olesen, Arne Vestergaard

1998-01-01

Two detailed geoids have been computed in the region of North Jutland. The first computation used marine data in the offshore areas. For the second computation the marine data set was replaced by the sparser airborne gravity data resulting from the AG-MASCO campaign of September 1996. The results...... of comparisons of the geoid heights at on-shore geometric control showed that the geoid heights computed from the airborne gravity data matched in precision those computed using the marine data, supporting the view that airborne techniques have enormous potential for mapping those unsurveyed areas between...

The influence of the atmosphere on geoid and potential coefficient determinations from gravity data

Science.gov (United States)

Rummel, R.; Rapp, R. H.

1976-01-01

For the precise computation of geoid undulations the effect of the attraction of the atmosphere on the solution of the basic boundary value problem of gravimetric geodesy must be considered. This paper extends the theory of Moritz for deriving an atmospheric correction to the case when the undulations are computed by combining anomalies in a cap surrounding the computation point with information derived from potential coefficients. The correction term is a function of the cap size and the topography within the cap. It reaches a value of 3.0 m for a cap size of 30 deg, variations on the decimeter level being caused by variations in the topography. The effect of the atmospheric correction terms on potential coefficients is found to be small, reaching a maximum of 0.0055 millionths at n = 2, m = 2 when terrestrial gravity data are considered. The magnitude of this correction indicates that in future potential coefficient determination from gravity data the atmospheric correction should be made to such data.

The northern European geoid: a case study on long-wavelength geoid errors

DEFF Research Database (Denmark)

Omang, O.C.D.; Forsberg, René

2002-01-01

. This method of removing lower-order terms in the Stokes kernel appears to improve the geoid. The best fit to the global positioning system (GPS) leveling points is obtained with a degree of modification of approximately 30. In addition to the study of modification errors, the results of different methods...

Comparisons of geoid models over Alaska computed with different Stokes' kernel modifications

Science.gov (United States)

Li, X.; Wang, Y.

2011-01-01

Various Stokes kernel modification methods have been developed over the years. The goal of this paper is to test the most commonly used Stokes kernel modifications numerically by using Alaska as a test area and EGM08 as a reference model. The tests show that some methods are more sensitive than others to the integration cap sizes. For instance, using the methods of Vaníček and Kleusberg or Featherstone et al. with kernel modification at degree 60, the geoid decreases by 30 cm (on average) when the cap size increases from 1° to 25°. The corresponding changes in the methods of Wong and Gore and Heck and Grüninger are only at the 1 cm level. At high modification degrees, above 360, the methods of Vaníček and Kleusberg and Featherstone et al become unstable because of numerical problems in the modification coefficients; similar conclusions have been reported by Featherstone (2003). In contrast, the methods of Wong and Gore, Heck and Grüninger and the least-squares spectral combination are stable at any modification degree, though they do not provide as good fit as the best case of the Molodenskii-type methods at the GPS/Leveling benchmarks. However, certain tests for choosing the cap size and modification degree have to be performed in advance to avoid abrupt mean geoid changes if the latter methods are applied.

Gravimetric Model of Quasigeoid in the Area of Slovakia

Directory of Open Access Journals (Sweden)

Juraj Papčo

2005-06-01

Full Text Available The gravimetric model of quasigeoid in the area of Slovakia was determined by using the revised and homogenised gravity mapping data in the scale of 1:25 000 from the area of Slovakia, and by using the mean Bouguer gravity anomalies with the resolution of 5´x7.5´ in the area 44°<φ<56° and 12°<λ<30° from abroad and by the digital terrain model DMR-2/ERTS89 with the resolution 3“ in the ellipsoidal latitude and 5“ in the ellipsoidal longitude from the area of Slovakia and the digital terrain model GTOPO30 with the resolution of 30“ in the ellipsoidal latitude and 30“ in the ellipsoidal longitude from abroad. The global part of the height anomaly was determined from the global geopotential model EGM96. The residual part of the height anomaly was determined by the Stokes integral formula. For the solution of the Stokes integra,l the Fast Fourier Transformation method in the spherical approximation was used. The gravimetric quasigeoid was tested by the GPS/levelling method using 46 points distributed on the area of Slovakia. The systematic trend of differences between height anomalies was rejected by the surface polynomial of second degree with 6 coefficients. The standard deviation after removing a systematic trend was 0.017 m

Oceanic geoid and tides derived from GEOS 3 satellite data in the Northwestern Atlantic Ocean

Science.gov (United States)

Won, I. J.; Miller, L. S.

1979-01-01

Two sets of GEOS 3 altimeter data which fall within about a 2.5-deg width are analyzed for ocean geoid and tides. One set covers a path from Newfoundland to Cuba, and the other a path from Puerto Rico to the North Carolina coast. Forty different analyses using various parameters are performed in order to investigate convergence. Profiles of the geoid and four tides, M2, O1, S2, and K1, are derived along the two strips. While the analyses produced convergent solutions for all 40 cases, the uncertainty caused by the linear orbital bias error of the satellite is too large to claim that the solutions represent the true ocean tides in the area. A spot check of the result with the Mode deep-sea tide gauge data shows poor agreement. A positive conclusion of this study is that despite the uncertain orbital error the oceanic geoid obtained through this analysis can improve significantly the short-wavelength structure over existing spherical harmonic geoid models.

Satellite-derived geoid for the estimation of lithospheric cooling and ...

Indian Academy of Sciences (India)

The northern Indian Ocean consists of older Bay of Bengal (BOB) oceanic .... Andaman & Nicobar Islands m ... The long wavelength classical geoid anomaly over the northern Indian Ocean with the largest geoid anomaly low ... and 'Snm' are the mass distribution functions. ..... in the Pacific Plate that caused the long wave-.

Use of recent geoid models to estimate mean dynamic topography and geostrophic currents in South Atlantic and Brazil Malvinas confluence

Directory of Open Access Journals (Sweden)

Alexandre Bernardino Lopes

2012-03-01

Full Text Available The use of geoid models to estimate the Mean Dynamic Topography was stimulated with the launching of the GRACE satellite system, since its models present unprecedented precision and space-time resolution. In the present study, besides the DNSC08 mean sea level model, the following geoid models were used with the objective of computing the MDTs: EGM96, EIGEN-5C and EGM2008. In the method adopted, geostrophic currents for the South Atlantic were computed based on the MDTs. In this study it was found that the degree and order of the geoid models affect the determination of TDM and currents directly. The presence of noise in the MDT requires the use of efficient filtering techniques, such as the filter based on Singular Spectrum Analysis, which presents significant advantages in relation to conventional filters. Geostrophic currents resulting from geoid models were compared with the HYCOM hydrodynamic numerical model. In conclusion, results show that MDTs and respective geostrophic currents calculated with EIGEN-5C and EGM2008 models are similar to the results of the numerical model, especially regarding the main large scale features such as boundary currents and the retroflection at the Brazil-Malvinas Confluence.A utilização de modelos geoidais na determinação da Topografia Dinâmica Média foi impulsionada com o lançamento dos satélites do sistema GRACE, já que seus modelos apresentam precisão e resolução espacial e temporal sem precedentes. No presente trabalho, além do modelo de nível médio do mar DNSC08, foram utilizados os seguintes modelos geoidais com o objetivo de calcular as TDMs: EGM96, EIGEN-5C e EGM2008. No método adotado, foram calculadas as respectivas correntes geostróficas para o Atlântico Sul a partir das TDMs. O grau e ordem dos modelos geoidais influenciam diretamente na determinação da TDM e correntes. Neste trabalho verificou-se que presença de ruídos da TDM requer a utilização de técnicas de filtragem

Different ways to handle topography in practical geoid determination

DEFF Research Database (Denmark)

Dahl, O.C.; Forsberg, René

1999-01-01

In this paper two different methods of how to handle topography in geoid determination is investigated. First method employs the Residual Terrain Model (RTM) remove-restore technique and yields the quasigeoid, whereas the second method is the classical Helmert condensation method, yielding...... the topography was represented by either a detailed (100 m) or a coarse (1000 m) digital terrain model. The inclusion of bathymetry in the terrain model was also investigated. Even if two different methods were used, they produced almost identical results at the 5 cm level in the mountains, but small systematic...

Local Marine Geoid Variations and Jason-2 Bias Determination using the Gavdos Permanent Cal/Val Facility

DEFF Research Database (Denmark)

Mertikas, S. P.; Daskalakis, A.; Tziavos, I. N.

2012-01-01

This work outlines how changes in steep bathymetry (from 200 m to 3500 m depth over a distance of 10 km) are reflected on the determined sea surface anomalies at the Gavdos site used for satellite altimeter calibration. After almost 4 years of Jason-2 calibration activities, it has been observed......, but others are related to under-sampling of the Earth's gravity field due to the resolution of the geoid model. New reference surfaces for calibration have thus emerged. Finally, new updated values for the Jason-2 altimeter bias have been determined as 191.81 ± 2.80 mm with the geoid model and as 181.51 ± 2...

Towards an exact relativistic theory of Earth's geoid undulation

Science.gov (United States)

Kopeikin, Sergei M.; Mazurova, Elena M.; Karpik, Alexander P.

2015-08-01

The present paper extends the Newtonian concept of the geoid in classic geodesy towards the realm of general relativity by utilizing the covariant geometric methods of the perturbation theory of curved manifolds. It yields a covariant definition of the anomalous (disturbing) gravity potential and formulates differential equation for it in the form of a covariant Laplace equation. The paper also derives the Bruns equation for calculation of geoid's height with full account for relativistic effects beyond the Newtonian approximation. A brief discussion of the relativistic Bruns formula is provided.

Geoid-to-Quasigeoid Separation Computed Using the GRACE/GOCE Global Geopotential Model GOCO02S - A Case Study of Himalayas and Tibet

Directory of Open Access Journals (Sweden)

Mohammad Bagherbandi Robert Tenzer

2013-01-01

Full Text Available The geoid-to-quasigeoid correction has been traditionally computed approximately as a function of the planar Bouguer gravity anomaly and the topographic height. Recent numerical studies based on newly developed theoretical models, however, indicate that the computation of this correction using the approximate formula yields large errors especially in mountainous regions with computation points at high elevations. In this study we investigate these approximation errors at the study area which comprises Himalayas and Tibet where this correction reaches global maxima. Since the GPS-leveling and terrestrial gravity datasets in this part of the world are not (freely available, global gravitational models (GGMs are used to compute this correction utilizing the expressions for a spherical harmonic analysis of the gravity field. The computation of this correction can be done using the GGM coefficients taken from the Earth Gravitational Model 2008 (EGM08 complete to degree 2160 of spherical harmonics. The recent studies based on a regional accuracy assessment of GGMs have shown that the combined GRACE/GOCE solutions provide a substantial improvement of the Earth¡¦s gravity field at medium wavelengths of spherical harmonics compared to EGM08. We address this aspect in numerical analysis by comparing the gravity field quantities computed using the satellite-only combined GRACE/GOCE model GOCO02S against the EGM08 results. The numerical results reveal that errors in the geoid-to-quasigeoid correction computed using the approximate formula can reach as much as ~1.5 m. We also demonstrate that the expected improvement of the GOCO02S gravity field quantities at medium wavelengths (within the frequency band approximately between 100 and 250 compared to EGM08 is as much as ±60 mGal and ±0.2 m in terms of gravity anomalies and geoid/quasigeoid heights respectively.

ON THE COMPUTATION OF A PRECISE GEOID – TO – QUASIGEOID SEPARATION

Directory of Open Access Journals (Sweden)

S. Hejrati

2017-09-01

Full Text Available In geodesy, orthometric and normal heights are considered as basic height systems on the earth. The reference surfaces for these heights are the geoid and quasigeoid respectively. Taking advantage of GNSS measurements, one can achieve a precise solution for the geoid and for the quasigeoid. Two methods, called direct and indirect, are worked out in this research for the computation of separation between geoid and quasigeoid in a mountainous region in the USA. The area selected for this purpose is mountainous and rough enough in order to be able to show the effect of roughness of topography in the sought quantity. The results of the two methods and testing them against GNSS-Levelling on 445 known points indicates an accuracy of 1.3 cm in RMS scale with the direct method, where there is 7 cm as an average difference between the observed geoid and quasigeoid separation and the same quantity derived from the direct method. Using Chi-squared goodness of fit test showed that the distribution of the residual quantities are normally distributed in the test area.

In defense of the classical height system

Science.gov (United States)

Foroughi, Ismael; Vaníček, Petr; Sheng, Michael; Kingdon, Robert William; Santos, Marcelo C.

2017-11-01

leveling points range between - 9.5 and 0 cm, differences between Helmert's and the rigorous orthometric heights vary between - 3.6 and 1.1 cm. The local gravimetric geoid model of Auvergne, computed by the Stokes-Helmert technique, is used here to illustrate the accuracy of the classical height system. Results show a very reasonable standard deviation (STD) of 3.2 cm of the differences between geoid values, derived from control leveling points, and gravimetric geoid heights when Helmert's heights are employed and even a smaller STD of 2.9 cm when rigorous orthometric heights are used. A corresponding comparison of a quasi-geoid model, computed by Least-Squares Modification of Stokes method, with normal heights show an STD of 3.4 cm.

A Study on Earthquake-Related Geoid Deformation at Beijing-Tangshan and West Yunnan During 1985-1998

Science.gov (United States)

Li, Z.

2006-05-01

Based on the determination of the non-tidal variations in the deflection of the vertical (or PlumbLine Variations, PLVs) at Beijing astronomical observatory, the work has been extended into a determination of the PLV array within a 4 x 1 (degree) area at Beijing-Tangshan. By repeated observations of the gravimetric network, 46 batches of this PLV array, and consequently the relative geoid deformation (RGD), of the area during 1987- 1998 have been determined. Together with the 23 earthquakes (Mb > 4.0) in the area during the same period, a comparison is done between an earthquake event and the related RGD. Similar study has also been carried out for the case in West Yunnan, where 32 batches of repeated gravimetric observations of the network there during 1985-1998 have been performed from which the 32 PLV array, as well as the corresponding RGD, of a 2 x 2 (dergee) area has been calculated. A comparison is also done at West Yunnan between an earthquake event and its related RGD. It is interesting to see that the earthquake and the RGD measured are related. It appears that there is usually a detectable RGD nearby well before an earthquake, but a contrary RGD afterwards. The study provides us a new approach in geodesy on the RGD determination, as well as a new measurable phenomenon in an earthquake event at Beijing-Tangshan and West Yunnan. The study also provides us evidence in which the existence of the PLVs, as well as the corresponding RGD, at Beijing- Tangshan and West Yunnan becomes more conclusive. Their potential usage in geodesy and seismology, as well as in other related sciences, is now expected.

Altimetry, bathymetry and geoid variations at the Gavdos permanent Cal/Val facility

DEFF Research Database (Denmark)

Mertikas, Stelios P.; Daskalakis, Antonis; Tziavos, Ilias N.

2013-01-01

The aim of this work has been to examine the relationship of steep bathymetry in the coastal areas around the permanent Cal/Val facility of Gavdos, and their influence on the produced calibration values for the Jason-2 satellite altimeter. The paper describes how changes in seafloor topography...... (from 200 to 3500m depth over a distance of 10km) are reflected on the determined altimeter parameters using different reference surfaces for satellite calibration. Finally, it describes the relation between these parameter trends and the region’s local characteristics.Using 3.5years of Jason-2...... to be related to the general oceanographic circulation, but others of short wavelength (in the order of 1km) are because of the insufficient geoid model resolution. Along Pass No. 109, the concealed effect of bathymetry on the geoid has produced a slope of 3.1cm over 14–21km from Gavdos. Along the other Pass No...

Arctic Ocean gravity, geoid and sea-ice freeboard heights from ICESat and GRACE

DEFF Research Database (Denmark)

Forsberg, René; Skourup, Henriette

2005-01-01

Gravity Project in combination with GRACE gravity field models to derive an improved Arctic geoid model. This model is then used to convert ICESat measurements to sea-ice freeboard heights with a coarse lowest-level surface method. The derived freeboard heights show a good qualitative agreement...... all major tectonic features of the Arctic Ocean, and has an accuracy of 6 mGal compared to recent airborne gravity data, illustrating the usefulness of ICESat data for gravity field determination....

A conventional value for the geoid reference potential

Czech Academy of Sciences Publication Activity Database

Sánchez, L.; Čundrlík, R.; Dayoub, N.; Mikula, K.; Minarechová, Z.; Šíma, Zdislav; Vatrt, V.; Vojtíšková, M.

2016-01-01

Roč. 90, č. 9 (2016), s. 815-835 ISSN 0949-7714 Institutional support: RVO:67985815 Keywords : gobal W-0 value * W-0 best estimate * potential value of the geoid Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 2.949, year: 2016

Reference Ellipsoid and Geoid in Chronometric Geodesy

Science.gov (United States)

Kopeikin, Sergei M.

2016-02-01

Chronometric geodesy applies general relativity to study the problem of the shape of celestial bodies including the earth, and their gravitational field. The present paper discusses the relativistic problem of construction of a background geometric manifold that is used for describing a reference ellipsoid, geoid, the normal gravity field of the earth and for calculating geoid's undulation (height). We choose the perfect fluid with an ellipsoidal mass distribution uniformly rotating around a fixed axis as a source of matter generating the geometry of the background manifold through the Einstein equations. We formulate the post-Newtonian hydrodynamic equations of the rotating fluid to find out the set of algebraic equations defining the equipotential surface of the gravity field. In order to solve these equations we explicitly perform all integrals characterizing the interior gravitational potentials in terms of elementary functions depending on the parameters defining the shape of the body and the mass distribution. We employ the coordinate freedom of the equations to choose these parameters to make the shape of the rotating fluid configuration to be an ellipsoid of rotation. We derive expressions of the post-Newtonian mass and angular momentum of the rotating fluid as functions of the rotational velocity and the parameters of the ellipsoid including its bare density, eccentricity and semi-major axes. We formulate the post-Newtonian Pizzetti and Clairaut theorems that are used in geodesy to connect the parameters of the reference ellipsoid to the polar and equatorial values of force of gravity. We expand the post-Newtonian geodetic equations characterizing the reference ellipsoid into the Taylor series with respect to the eccentricity of the ellipsoid, and discuss the small-eccentricity approximation. Finally, we introduce the concept of relativistic geoid and its undulation with respect to the reference ellipsoid, and discuss how to calculate it in chronometric

Application, advantages and limitations of high-density gravimetric surveys compared with three-dimensional geological modelling in dolomite stability investigations

OpenAIRE

Breytenbach, I J; Bosch, P J A

2011-01-01

The article discusses the nature of the gravimetric survey as applied and used in dolomite stability investigations on areas underlain by the Chuniespoort Group in South Africa. A short discussion is given on the gravimetric survey procedure along with its uses and alternative methods. Finally, two case studies illustrate the application of the method on a high-density survey grid spacing in comparison with three-dimensional geological modelling based on the lithology and karst weathering hor...

Modeling the North American vertical datum of 1988 errors in the conterminous United States

Science.gov (United States)

Li, X.

2018-02-01

A large systematic difference (ranging from -20 cm to +130 cm) was found between NAVD 88 (North AmericanVertical Datum of 1988) and the pure gravimetric geoid models. This difference not only makes it very difficult to augment the local geoid model by directly using the vast NAVD 88 network with state-of-the-art technologies recently developed in geodesy, but also limits the ability of researchers to effectively demonstrate the geoid model improvements on the NAVD 88 network. Here, both conventional regression analyses based on various predefined basis functions such as polynomials, B-splines, and Legendre functions and the Latent Variable Analysis (LVA) such as the Factor Analysis (FA) are used to analyze the systematic difference. Besides giving a mathematical model, the regression results do not reveal a great deal about the physical reasons that caused the large differences in NAVD 88, which may be of interest to various researchers. Furthermore, there is still a significant amount of no-Gaussian signals left in the residuals of the conventional regression models. On the other side, the FA method not only provides a better not of the data, but also offers possible explanations of the error sources. Without requiring extra hypothesis tests on the model coefficients, the results from FA are more efficient in terms of capturing the systematic difference. Furthermore, without using a covariance model, a novel interpolating method based on the relationship between the loading matrix and the factor scores is developed for predictive purposes. The prediction error analysis shows that about 3-7 cm precision is expected in NAVD 88 after removing the systematic difference.

Modeling the North American vertical datum of 1988 errors in the conterminous United States

Directory of Open Access Journals (Sweden)

Li X.

2018-02-01

Full Text Available A large systematic difference (ranging from −20 cm to +130 cm was found between NAVD 88 (North AmericanVertical Datum of 1988 and the pure gravimetric geoid models. This difference not only makes it very difficult to augment the local geoid model by directly using the vast NAVD 88 network with state-of-the-art technologies recently developed in geodesy, but also limits the ability of researchers to effectively demonstrate the geoid model improvements on the NAVD 88 network. Here, both conventional regression analyses based on various predefined basis functions such as polynomials, B-splines, and Legendre functions and the Latent Variable Analysis (LVA such as the Factor Analysis (FA are used to analyze the systematic difference. Besides giving a mathematical model, the regression results do not reveal a great deal about the physical reasons that caused the large differences in NAVD 88, which may be of interest to various researchers. Furthermore, there is still a significant amount of no-Gaussian signals left in the residuals of the conventional regression models. On the other side, the FA method not only provides a better not of the data, but also offers possible explanations of the error sources. Without requiring extra hypothesis tests on the model coefficients, the results from FA are more efficient in terms of capturing the systematic difference. Furthermore, without using a covariance model, a novel interpolating method based on the relationship between the loading matrix and the factor scores is developed for predictive purposes. The prediction error analysis shows that about 3-7 cm precision is expected in NAVD 88 after removing the systematic difference.

Interpretation of Gravimetric and Aeromagnetic Data of the Tecoripa Chart in Southeast Sonora, Mexico.

Science.gov (United States)

Martínez-Retama, S.; Montaño-Del Cid, M. A.

2015-12-01

The Tecoripa chart H12-D64 is located southeast of the state of Sonora, México, south of Arizona. The geology is represented by sedimentary rocks of the Ordovician and Triassic, volcanic rocks of the Upper Cretaceous and Tertiary, intrusive rocks from the Upper Cretaceous- Tertiary and sedimentary rocks of the Cenozoic. In this paper a gravimetric study was conducted to determine the configuration and depth of the basement and to develop a structural model of the subsurface. For this purpose a consistent gravimetric survey in 3 profiles was conducted. To complement this study, gravimetric data obtained by INEGI (96 gravimetric stations spaced every 4000 m) that correspond to a regional survey was also used. The two sets of data were corrected and processed with the WinGLink software. The profiles were then modeled using the Talwani method. 4 Profiles corresponding to the gravimetric survey and 5 data profiles from INEGI were modeled. Aeromagnetic data from the total field of Tecoripa chart were also processed. The digital information was integrated and processed by generating a data grid. Processes applied to data consisted of reduction to the pole, regional-residual separation and upward continuations. In general, the obtained structural models show intrusive bodies associated with well-defined high gravimetric and magnetic and low gravimetric and magnetic are associated with basins and sedimentary rocks. The obtained geological models show the basement represented by volcanic rocks of the Tarahumara Formation from the Upper Cretaceous which are in contact with sedimentary rocks from the Barranca Group from Upper Cretaceous and limestones from the Middle Ordovician. Both volcanic and sedimentary rocks are intruded by granodiorite- granite with ages of the Tertiary-Oligocene. Based on the superficial geology as well as in the configuration of the basement and the obtained structural model the existence of faults with NW-SE orientation that originate Horst and

Reference ellipsoid and geoid in chronometric geodesy

Directory of Open Access Journals (Sweden)

Sergei M Kopeikin

2016-02-01

Full Text Available Chronometric geodesy applies general relativity to study the problem of the shape of celestial bodies including the earth, and their gravitational field. The present paper discusses the relativistic problem of construction of a background geometric manifold that is used for describing a reference ellipsoid, geoid, the normal gravity field of the earth and for calculating geoid's undulation (height. We choose the perfect fluid with an ellipsoidal mass distribution uniformly rotating around a fixed axis as a source of matter generating the geometry of the background manifold through the Einstein equations. We formulate the post-Newtonian hydrodynamic equations of the rotating fluid to find out the set of algebraic equations defining the equipotential surface of the gravity field. In order to solve these equations we explicitly perform all integrals characterizing the interior gravitational potentials in terms of elementary functions depending on the parameters defining the shape of the body and the mass distribution. We employ the coordinate freedom of the equations to choose these parameters to make the shape of the rotating fluid configuration to be an ellipsoid of rotation. We derive expressions of the post-Newtonian mass and angular momentum of the rotating fluid as functions of the rotational velocity and the parameters of the ellipsoid including its bare density, eccentricity and semi-major axes. We formulate the post-Newtonian Pizzetti and Clairaut theorems that are used in geodesy to connect the parameters of the reference ellipsoid to the polar and equatorial values of force of gravity. We expand the post-Newtonian geodetic equations characterizing the reference ellipsoid into the Taylor series with respect to the eccentricity of the ellipsoid, and discuss the small-eccentricity approximation. Finally, we introduce the concept of relativistic geoid and its undulation with respect to the reference ellipsoid, and discuss how to calculate it

Reference Ellipsoid and Geoid in Chronometric Geodesy

Energy Technology Data Exchange (ETDEWEB)

Kopeikin, Sergei M., E-mail: kopeikins@missouri.edu [Department of Physics and Astronomy, University of Missouri, Columbia, MO (United States); Department of Physical Geodesy and Remote Sensing, Siberian State University of Geosystems and Technologies, Novosibirsk (Russian Federation)

2016-02-25

Chronometric geodesy applies general relativity to study the problem of the shape of celestial bodies including the earth, and their gravitational field. The present paper discusses the relativistic problem of construction of a background geometric manifold that is used for describing a reference ellipsoid, geoid, the normal gravity field of the earth and for calculating geoid's undulation (height). We choose the perfect fluid with an ellipsoidal mass distribution uniformly rotating around a fixed axis as a source of matter generating the geometry of the background manifold through the Einstein equations. We formulate the post-Newtonian hydrodynamic equations of the rotating fluid to find out the set of algebraic equations defining the equipotential surface of the gravity field. In order to solve these equations we explicitly perform all integrals characterizing the interior gravitational potentials in terms of elementary functions depending on the parameters defining the shape of the body and the mass distribution. We employ the coordinate freedom of the equations to choose these parameters to make the shape of the rotating fluid configuration to be an ellipsoid of rotation. We derive expressions of the post-Newtonian mass and angular momentum of the rotating fluid as functions of the rotational velocity and the parameters of the ellipsoid including its bare density, eccentricity and semi-major axes. We formulate the post-Newtonian Pizzetti and Clairaut theorems that are used in geodesy to connect the parameters of the reference ellipsoid to the polar and equatorial values of force of gravity. We expand the post-Newtonian geodetic equations characterizing the reference ellipsoid into the Taylor series with respect to the eccentricity of the ellipsoid, and discuss the small-eccentricity approximation. Finally, we introduce the concept of relativistic geoid and its undulation with respect to the reference ellipsoid, and discuss how to calculate it in

High-resolution residual geoid and gravity anomaly data of the northern Indian Ocean - An input to geological understanding

Digital Repository Service at National Institute of Oceanography (India)

Sreejith, K.M.; Rajesh, S.; Majumdar, T.J.; Rao, G.S.; Radhakrishna, M.; Krishna, K.S.; Rajawat, A.S.

') geoid anomaly map of the northern Indian Ocean generated from the altimeter data obtained from Geodetic Missions of GEOSAT and ERS-1 along with ERS-2, TOPEX/POSIDEON and JASON satellites is presented. The geoid map of the Indian Ocean is dominated by a...

Ocean tides and quasi-stationary departures from the marine geoid investigation

Science.gov (United States)

Siry, J. W.; Kahn, W. D.; Bryan, J. W.; Vonbun, F. O.

1973-01-01

The detection of tides and/or currents through the analysis of data generated in connection with the Ocean Geoid Determination Investigation is presented. A discussion of the detailed objectives and approach are included.

Residual gravimetric method to measure nebulizer output.

Science.gov (United States)

Vecellio None, Laurent; Grimbert, Daniel; Bordenave, Joelle; Benoit, Guy; Furet, Yves; Fauroux, Brigitte; Boissinot, Eric; De Monte, Michele; Lemarié, Etienne; Diot, Patrice

2004-01-01

The aim of this study was to assess a residual gravimetric method based on weighing dry filters to measure the aerosol output of nebulizers. This residual gravimetric method was compared to assay methods based on spectrophotometric measurement of terbutaline (Bricanyl, Astra Zeneca, France), high-performance liquid chromatography (HPLC) measurement of tobramycin (Tobi, Chiron, U.S.A.), and electrochemical measurements of NaF (as defined by the European standard). Two breath-enhanced jet nebulizers, one standard jet nebulizer, and one ultrasonic nebulizer were tested. Output produced by the residual gravimetric method was calculated by weighing the filters both before and after aerosol collection and by filter drying corrected by the proportion of drug contained in total solute mass. Output produced by the electrochemical, spectrophotometric, and HPLC methods was determined after assaying the drug extraction filter. The results demonstrated a strong correlation between the residual gravimetric method (x axis) and assay methods (y axis) in terms of drug mass output (y = 1.00 x -0.02, r(2) = 0.99, n = 27). We conclude that a residual gravimetric method based on dry filters, when validated for a particular agent, is an accurate way of measuring aerosol output.

Radial profiles of temperature and viscosity in the Earth's mantle inferred from the geoid and lateral seismic structure

NARCIS (Netherlands)

Cadek, O.; Berg, A.P. van den

1998-01-01

In the framework of dynamical modelling of the geoid, we have estimated basic features of the radial profile of temperature in the mantle. The applied parameterization of the geotherm directly characterizes thermal boundary layers and values of the thermal gradient in the upper and lower mantle.

Gravimetric determination of uranium in SALE samples

International Nuclear Information System (INIS)

Anon.

1981-01-01

As a participant in the Safeguards Analytical Laboratory Evaluation (SALE) program, the Analytical Chemistry Laboratory at General Atomic routinely assays uranium dioxide and uranyl nitrate SALE samples for uranium content. Gravimetric methods are relatively easy and inexpensive to apply when the samples for uranium content. Gravimetric methods are relatively easy and inexpensive to apply when the samples are free from substantial amounts of metallic impurities. Clearly the gravimetric procedure alone is not specific for uranium and must be enhanced by the use of impurity corrections. Emission spectrography is used routinely as the technique of choice for making such corrections. In cases where it is essential to assay specifically for uranium, the modified Davies-Gray titration using a weighed titrant method is applied. In this paper some essential features of these gravimetric and titrimetric procedures are discussed

Precisión de la aproximación geoide y geoestadística: cómo encontrar un mapa contínuo de datos de gravedad absoluta

Directory of Open Access Journals (Sweden)

Hongzhi Song

2015-10-01

Full Text Available An accurate geoid model is needed for surveyors and engineers who require orthometric heights on a common datum, and environ- ment scientists who require elevations relative to present sea level. Airborne gravity data has been collected by the National Geodetic Survey (NGS under the Gravity for the Redefinition of the Amer- ican Vertical Datum (GRAV-D project and is available along the coasts of the Gulf of Mexico. For this study we obtained a set of abso- lute gravity data derived from full-field gravity at altitude/elevation. We used the data to derive free-air gravity anomalies to establish gravity on the geoid. For spatial interpolation we used the kriging method to estimate gravity on the geoid in any location and krig- ing of the difference between gravity on the ellipsoid of reference and the geoid. Various kriging methods were used for evaluation of errors calculated in this study. The mean precision of the predicted val- ues is around 1.23 cm, a very good result for coastal regions, which traditionally have sparse gravity data sets.

The first Australian gravimetric quasigeoid model with location-specific uncertainty estimates

Science.gov (United States)

Featherstone, W. E.; McCubbine, J. C.; Brown, N. J.; Claessens, S. J.; Filmer, M. S.; Kirby, J. F.

2018-02-01

We describe the computation of the first Australian quasigeoid model to include error estimates as a function of location that have been propagated from uncertainties in the EGM2008 global model, land and altimeter-derived gravity anomalies and terrain corrections. The model has been extended to include Australia's offshore territories and maritime boundaries using newer datasets comprising an additional {˜ }280,000 land gravity observations, a newer altimeter-derived marine gravity anomaly grid, and terrain corrections at 1^' ' }× 1^' ' } resolution. The error propagation uses a remove-restore approach, where the EGM2008 quasigeoid and gravity anomaly error grids are augmented by errors propagated through a modified Stokes integral from the errors in the altimeter gravity anomalies, land gravity observations and terrain corrections. The gravimetric quasigeoid errors (one sigma) are 50-60 mm across most of the Australian landmass, increasing to {˜ }100 mm in regions of steep horizontal gravity gradients or the mountains, and are commensurate with external estimates.

Comparison of the gravimetric, phenol red, and 14C-PEG-3350 methods to determine water absorption in the rat single-pass intestinal perfusion model.

Science.gov (United States)

Sutton, S C; Rinaldi, M T; Vukovinsky, K E

2001-01-01

This study was undertaken to determine whether the gravimetric method provided an accurate measure of water flux correction and to compare the gravimetric method with methods that employ nonabsorbed markers (eg, phenol red and 14C-PEG-3350). Phenol red,14C-PEG-3350, and 4-[2-[[2-(6-amino-3-pyridinyl)-2-hydroxyethyl]amino]ethoxy]-, methyl ester, (R)-benzene acetic acid (Compound I) were co-perfused in situ through the jejunum of 9 anesthetized rats (single-pass intestinal perfusion [SPIP]). Water absorption was determined from the phenol red,14C-PEG-3350, and gravimetric methods. The absorption rate constant (ka) for Compound I was calculated. Both phenol red and 14C-PEG-3350 were appreciably absorbed, underestimating the extent of water flux in the SPIP model. The average +/- SD water flux microg/h/cm) for the 3 methods were 68.9 +/- 28.2 (gravimetric), 26.8 +/- 49.2 (phenol red), and 34.9 +/- 21.9 (14C-PEG-3350). The (average +/- SD) ka for Compound I (uncorrected for water flux) was 0.024 +/- 0.005 min(-1). For the corrected, gravimetric method, the average +/- SD was 0.031 +/- 0.001 min(-1). The gravimetric method for correcting water flux was as accurate as the 2 "nonabsorbed" marker methods.

Lithospheric structure of southern Indian shield and adjoining oceans: integrated modelling of topography, gravity, geoid and heat flow data

Science.gov (United States)

Kumar, Niraj; Zeyen, H.; Singh, A. P.; Singh, B.

2013-07-01

For the present 2-D lithospheric density modelling, we selected three geotransects of more than 1000 km in length each crossing the southern Indian shield, south of 16°N, in N-S and E-W directions. The model is based on the assumption of local isostatic equilibrium and is constrained by the topography, gravity and geoid anomalies, by geothermal data, and where available by seismic data. Our integrated modelling approach reveals a crustal configuration with the Moho depth varying from ˜40 km beneath the Dharwar Craton, and ˜39 km beneath the Southern Granulite Terrane to about 15-20 km beneath the adjoining oceans. The lithospheric thickness varies significantly along the three profiles from ˜70-100 km under the adjoining oceans to ˜130-135 km under the southern block of Southern Granulite Terrane including Sri Lanka and increasing gradually to ˜165-180 km beneath the northern block of Southern Granulite Terrane and the Dharwar Craton. This step-like lithosphere-asthenosphere boundary (LAB) structure indicates a normal lithospheric thickness beneath the adjoining oceans, the northern block of Southern Granulite Terrane and the Dharwar Craton. The thin lithosphere below the southern block of Southern Granulite Terrane including Sri Lanka is, however, atypical considering its age. Our results suggest that the southern Indian shield as a whole cannot be supported isostatically only by thickened crust; a thin and hot lithosphere beneath the southern block of Southern Granulite Terrane including Sri Lanka is required to explain the high topography, gravity, geoid and crustal temperatures. The widespread thermal perturbation during Pan-African (550 Ma) metamorphism and the breakup of Gondwana during late Cretaceous are proposed as twin cause mechanism for the stretching and/or convective removal of the lower part of lithospheric mantle and its replacement by hotter and lighter asthenosphere in the southern block of Southern Granulite Terrane including Sri Lanka

OSGM02: A new model for converting GPS-derived heights to local height datums in Great Britain and Ireland

DEFF Research Database (Denmark)

Iliffe, J.C.; Ziebart, M.; Cross, P.A.

2003-01-01

The background to the recent computation of a new vertical datum model for the British Isles (OSGM02) is described After giving a brief description of the computational techniques and the data sets used for the derivation of the gravimetric geoid, the paper focuses on the fitting of this surface...... to the GPS and levelling networks in the various regions of the British Isles in such a way that it can be used in conjunction with GPS to form a replacement for the existing system of bench marks. The error sources induced in this procedure are discussed, and the theoretical basis given for the fitting...

Goce derived geoid changes before the Pisagua 2014 earthquake

Directory of Open Access Journals (Sweden)

Orlando Álvarez

2018-01-01

Full Text Available The analysis of space – time surface deformation during earthquakes reveals the variable state of stress that occurs at deep crustal levels, and this information can be used to better understand the seismic cycle. Understanding the possible mechanisms that produce earthquake precursors is a key issue for earthquake prediction. In the last years, modern geodesy can map the degree of seismic coupling during the interseismic period, as well as the coseismic and postseismic slip for great earthquakes along subduction zones. Earthquakes usually occur due to mass transfer and consequent gravity variations, where these changes have been monitored for intraplate earthquakes by means of terrestrial gravity measurements. When stresses and correspondent rupture areas are large, affecting hundreds of thousands of square kilometres (as occurs in some segments along plate interface zones, satellite gravimetry data become relevant. This is due to the higher spatial resolution of this type of data when compared to terrestrial data, and also due to their homogeneous precision and availability across the whole Earth. Satellite gravity missions as GOCE can map the Earth gravity field with unprecedented precision and resolution. We mapped geoid changes from two GOCE satellite models obtained by the direct approach, which combines data from other gravity missions as GRACE and LAGEOS regarding their best characteristics. The results show that the geoid height diminished from a year to five months before the main seismic event in the region where maximum slip occurred after the Pisagua Mw = 8.2 great megathrust earthquake. This diminution is interpreted as accelerated inland-directed interseismic mass transfer before the earthquake, coinciding with the intermediate degree of seismic coupling reported in the region. We highlight the advantage of satellite data for modelling surficial deformation related to pre-seismic displacements. This deformation, combined to

Preliminary study of gravimetric anomalies in the Magallanes-Fagnano fault system, South America

Directory of Open Access Journals (Sweden)

Juan Manuel Alcacer

2018-01-01

Full Text Available The main objective of this research is to recognize several geological structures associated with the shear zones of the MFFS (Magallanes – Fagnano fault system by the analysis and interpretation of gravimetric anomalies. Besides, to compare the gravimetrical response of the cortical blocks that integrate the region under study, which is related to the different morphotectonic domains recognized in the region. This research was developed employing data obtained from World Gravity 1.0, which includes earth and satellite gravity data derived from the EGM2008 model. The study and interpretation of the MFFS from the analysis and processing of the gravimetric data, allowed appreciation of a noticeable correlation with the most superficial cortical structure.

Crustal thickness of Antarctica estimated using data from gravimetric satellites

Science.gov (United States)

Llubes, Muriel; Seoane, Lucia; Bruinsma, Sean; Rémy, Frédérique

2018-04-01

Computing a better crustal thickness model is still a necessary improvement in Antarctica. In this remote continent where almost all the bedrock is covered by the ice sheet, seismic investigations do not reach a sufficient spatial resolution for geological and geophysical purposes. Here, we present a global map of Antarctic crustal thickness computed from space gravity observations. The DIR5 gravity field model, built from GOCE and GRACE gravimetric data, is inverted with the Parker-Oldenburg iterative algorithm. The BEDMAP products are used to estimate the gravity effect of the ice and the rocky surface. Our result is compared to crustal thickness calculated from seismological studies and the CRUST1.0 and AN1 models. Although the CRUST1.0 model shows a very good agreement with ours, its spatial resolution is larger than the one we obtain with gravimetric data. Finally, we compute a model in which the crust-mantle density contrast is adjusted to fit the Moho depth from the CRUST1.0 model. In East Antarctica, the resulting density contrast clearly shows higher values than in West Antarctica.

Comparison of fine particle measurements from a direct-reading instrument and a gravimetric sampling method.

Science.gov (United States)

Kim, Jee Young; Magari, Shannon R; Herrick, Robert F; Smith, Thomas J; Christiani, David C

2004-11-01

Particulate air pollution, specifically the fine particle fraction (PM2.5), has been associated with increased cardiopulmonary morbidity and mortality in general population studies. Occupational exposure to fine particulate matter can exceed ambient levels by a large factor. Due to increased interest in the health effects of particulate matter, many particle sampling methods have been developed In this study, two such measurement methods were used simultaneously and compared. PM2.5 was sampled using a filter-based gravimetric sampling method and a direct-reading instrument, the TSI Inc. model 8520 DUSTTRAK aerosol monitor. Both sampling methods were used to determine the PM2.5 exposure in a group of boilermakers exposed to welding fumes and residual fuel oil ash. The geometric mean PM2.5 concentration was 0.30 mg/m3 (GSD 3.25) and 0.31 mg/m3 (GSD 2.90)from the DUSTTRAK and gravimetric method, respectively. The Spearman rank correlation coefficient for the gravimetric and DUSTTRAK PM2.5 concentrations was 0.68. Linear regression models indicated that log, DUSTTRAK PM2.5 concentrations significantly predicted loge gravimetric PM2.5 concentrations (p gravimetric PM2.5 concentrations was found to be modified by surrogate measures for seasonal variation and type of aerosol. PM2.5 measurements from the DUSTTRAK are well correlated and highly predictive of measurements from the gravimetric sampling method for the aerosols in these work environments. However, results from this study suggest that aerosol particle characteristics may affect the relationship between the gravimetric and DUSTTRAK PM2.5 measurements. Recalibration of the DUSTTRAK for the specific aerosol, as recommended by the manufacturer, may be necessary to produce valid measures of airborne particulate matter.

What drives the Tibetan crust to the South East Asia? Role of upper mantle density discontinuities as inferred from the continental geoid anomalies

Science.gov (United States)

Rajesh, S.

2012-04-01

The Himalaya-Tibet orogen formed as a result of the northward convergence of India into the Asia over the past 55 Ma had caused the north south crustal shortening and Cenozoic upliftment of the Tibetan plateau, which significantly affected the tectonic and climatic framework of the Asia. Geodetic measurements have also shown eastward crustal extrusion of Tibet, especially along major east-southeast strike slip faults at a slip rate of 15-20 mm a-1 and around 40 mm a-1. Such continental scale deformations have been modeled as block rotation by fault boundary stresses developed due to the India-Eurasia collision. However, the Thin Sheet model explained the crustal deformation mechanism by considering varying gravitational potential energy arise out of varying crustal thickness of the viscous lithosphere. The Channel Flow model, which also suggests extrusion is a boundary fault guided flow along the shallow crustal brittle-ductile regime. Although many models have proposed, but no consensus in these models to explain the dynamics of measured surface geodetic deformation of the Tibetan plateau. But what remains conspicuous is the origin of driving forces that cause the observed Tibetan crustal flow towards the South East Asia. Is the crustal flow originated only because of the differential stresses that developed in the shallow crustal brittle-ductile regime? Or should the stress transfer to the shallow crustal layers as a result of gravitational potential energy gradient driven upper mantle flow also to be accounted. In this work, I examine the role of latter in the light of depth distribution of continental geoid anomalies beneath the Himalaya-Tibet across major upper mantle density discontinuities. These discontinuity surfaces in the upper mantle are susceptible to hold the plastic deformation that may occur as a result of the density gradient driven flow. The distribution of geoid anomalies across these density discontinuities at 220, 410 and 660 km depth in the

An Assessment of State-of-the-Art Mean Sea Surface and Geoid Models of the Arctic Ocean: Implications for Sea Ice Freeboard Retrieval

DEFF Research Database (Denmark)

Skourup, Henriette; Farrell, Sinéad Louise; Hendricks, Stefan

2017-01-01

in a given model in the high frequency domain, primarily due to unresolved gravity features, can result in errors in the estimated along-track freeboard. These errors are exacerbated in areas with a sparse lead distribution in consolidated ice pack conditions. Additionally model errors can impact ocean......State-of-the-art Arctic Ocean mean sea surface (MSS) models and global geoid models (GGMs) are used to support sea ice freeboard estimation from satellite altimeters, as well as in oceanographic studies such as mapping sea level anomalies and mean dynamic ocean topography. However, errors...... geostrophic currents, derived from satellite altimeter data, while remaining biases in these models may impact longer-term, multi-sensor oceanographic time-series of sea level change in the Arctic. This study focuses on an assessment of five state-of-the-art Arctic MSS models (UCL13/04, DTU15...

Some technical details concerning a new method of gravimetric-seismic inversion

DEFF Research Database (Denmark)

Strykowski, Gabriel

1999-01-01

In this paper a number of technical details related to a new method of gravimetric-seismic inversion, which is still under development, are explained. Although the present contribution aims on providing general statements on how to formulate and solve complex gravimetric-seismic modeling; problems......, the inspiration comes from the practical modeling problems in the area of Jutland peninsula (Denmark). More specifically, the methodological aspects of the proposed inversion method are illustrated on a problem of 3D modeling of the intra crustal intrusion associated with the Silkeborg Gravity High. The existing...... refraction seismic profile locates the source of the anomaly in depths 10 km - 18 km. In an earlier publication, (Strykowski, 1998), and for the same test area, a method of complex geological stripping is described. The present contribution is a continuation of this paper in the direction of inversion...

New geoid of Greenland: A case study of terrain and ice effects, GOCE and use of local sea level data

DEFF Research Database (Denmark)

Forsberg, René; Jensen, Tim Enzlberger

2015-01-01

Making an accurate geoid model of Greenland has always been a challenge due to the ice sheet and glaciers, and the rough topography and deep fjords in the ice free parts. Terrestrial gravity coverage has for the same reasons been relatively sparse, with an older airborne survey of the interior be...

[Preclinical study of immunocorrection action of the sum of active substances of Coluria geoides (Pall.) Ledeb. (Rosaceae)].

Science.gov (United States)

Dutova, S V; Karpova, M R; Myadelets, M A; Myasnaya, N V; Sherstoboev, E Yu

2015-01-01

A preclinical study of the immunocorrection action of the sum of active substances isolated from ethereal-oil plants Coluria geoides (Pall.) Ledeb. (Rosaceae family) with respect to experimental immunodeficiency showed that preparations relieve symptoms of immunodeficiency caused by the administration of cyclophosphan: suppressed synthesis of anti-erythrocyte antibodies (agglutinine) and proliferative processes in the spleen. Under the influence of C. geoides preparations, the absolute numbers of cariocytes and antibody forming cells in spleen significantly increased (compared to the group of animals with experimental immunodeficiency) and in some cases reached the background level. The drugs studied produced a more pronounced stimulating effect on the synthesis of specific immunoglobulins and proliferation of antibody forming cells of spleen as compared to the effect of Echinacea tincture. Preparation C-2 (extract from underground organs and grass of C. geoides obtained by percolation method with 70% ethanol) is most promising for in-depth research and the development of new effective drugs with immunocorrecting properties.

Modeling and Inversion of three-dimensional crustal structures beneath the Pyrenees and their foreland basins based upon geological, gravimetric and seismological data

Science.gov (United States)

Spangenberg, Hannah; Chevrot, Sébastien; Courrioux, Gabriel; Guillen, Antonio

2017-04-01

Our goal is to obtain a three-dimensional (3D) model of mass density and seismic velocities beneath the Pyrenees and their foreland basins (Aquitaine and Ebro basins), which accounts for all the geological and geophysical information available for that region. This model covers the whole mountain range going from the Atlantic Ocean to the Mediterranean Sea, and from the Iberian range to the Massif Central. The model is described by different units: the lower, middle, and upper crusts, the accretionary prism, and the consolidated and unconsolidated sediment layers. Furthermore, a sub-continental, serpentinized European mantle is introduced to describe the exhumed mantle bodies which are responsible for the positive Bouguer gravity anomalies in the western Pyrenees. We build a first 3D model using all the geological information: drill-hole surveys, seismic sections, and the geological map. We use the potential field method implemented in Geomodeler to interpolate these geological data. However, these data are too sparse to build a model that explains seismic travel times or gravimetric data, especially the Labourd and the St. Gaudens Bouguer gravity anomalies. In addition, inconsistencies between the different data sets exist. We thus add by trial and error additional data points, comparing modeled and observed Bouguer gravimetric anomalies. The result of this procedure is a 3D geological model that respects the geological data and explains the measured Bouguer gravimetric anomalies. In a second step, we use this model to determine the average density and seismic velocities inside each geological unit assuming uniform layers. To constrain the seismic velocities we use travel time picks extracted from the bulletin of the Pyrenean seismicity released by the Observatoire Midi Pyrenées. In a third step, we use this 3D a priori model in a Monte Carlo inversion to invert jointly gravimetric data and seismic travel times from the bulletin. This probabilistic approach

Crustal thickness of Antarctica estimated using data from gravimetric satellites

Directory of Open Access Journals (Sweden)

M. Llubes

2018-04-01

Full Text Available Computing a better crustal thickness model is still a necessary improvement in Antarctica. In this remote continent where almost all the bedrock is covered by the ice sheet, seismic investigations do not reach a sufficient spatial resolution for geological and geophysical purposes. Here, we present a global map of Antarctic crustal thickness computed from space gravity observations. The DIR5 gravity field model, built from GOCE and GRACE gravimetric data, is inverted with the Parker–Oldenburg iterative algorithm. The BEDMAP products are used to estimate the gravity effect of the ice and the rocky surface. Our result is compared to crustal thickness calculated from seismological studies and the CRUST1.0 and AN1 models. Although the CRUST1.0 model shows a very good agreement with ours, its spatial resolution is larger than the one we obtain with gravimetric data. Finally, we compute a model in which the crust–mantle density contrast is adjusted to fit the Moho depth from the CRUST1.0 model. In East Antarctica, the resulting density contrast clearly shows higher values than in West Antarctica.

Gravimetric model of the Gastre trough, province of Chubut, Argentina; Modelo gravimetrico en la fosa de Gastre, provincia de Chubut, Argentina

Energy Technology Data Exchange (ETDEWEB)

Lince Klinger, F.; Nacif, S.; Martinez, M. P.; Gimenez, M. E.; Ruiz, F.; Alvarez, O.

2011-07-01

A gravimetric study of the Gastre trough in the Province of Chubut, to the southwest of the Canadon Asfalto basin, has allowed us to determine the geometry of its crystalline basement. Using filtering techniques we were able to map residual Bouguer anomalies, which show the heterogeneities situated within the upper crust, some of which are linked to recognised geological structures. The gravimetric minima in the residual Bouguer anomaly map are associated with graben-type basins, flanked by positive gravity values associated with alignments identified on the surface and with the overall topographic relief of the Gastre trough. After suitable treatment of the density values of the outcrops and seismic data we were able to construct a 2D density model, perpendicular to the trough, which indicated a depth of 3600 m. The importance of this study lies in the fact that it has been possible to arrive at a gravimetric characterization of the Gastre trough in the Canadon Asfalto basin sector, a potentially hydrocarbon-bearing area hitherto lacking in reliable data concerning its subsoil. (Author)

Gravimetric geoid of a part of south India and its comparison with ...

Indian Academy of Sciences (India)

Indian region from terrestrial gravity and elevation data using remove–restore technique that involves ... the development models; it is necessary to com- ... Spirit levelling network in the area ... requires integration of the gravity field over whole.

Hydrologically induced orientation variations of a tri-axial Earth's principal axes based on satellite-gravimetric and hydrological models

Directory of Open Access Journals (Sweden)

Shen Wenbin

2013-05-01

Full Text Available The Earth is a tri-axial body, with unequal principal inertia moments, A, B and C. The corresponding principal axes a, b and c are determined by the mass distribution of the Earth, and their orientations vary with the mass redistribution. In this study, the hydrologically induced variations are estimated on the basis of satellite gravimetric data, including those from satellite laser ranging (SLR and gravity recovery and climate experiment (GRACE, and hydrological models from global land data assimilation system (GLDAS. The longitude variations of a and b are mainly related to the variations of the spherical harmonic coefficients C¯22 and S¯22, which have been estimated to be consisting annual variations of about 1. 6 arc seconds and 1. 8 arc seconds, respectively, from gravity data. This result is confirmed by land surface water storage provided by the GLDAS model. If the atmospheric and oceanic signals are removed from the spherical harmonic coefficients C¯21 and S¯21, the agreement of the orientation series for c becomes poor, possibly due to the inaccurate background models used in pre-processing of the satellite gravimetric data. Determination of the orientation variations may provide a better understanding of various phenomena in the study of the rotation of a tri-axial Earth.

Unraveling African plate structure from elevation, geoid and geology data

Science.gov (United States)

Chardon, Dominique; Bajolet, Flora; Robert, Alexandra; Rouby, Delphine

2014-05-01

The aim of our project is to simulate the long-wavelength, flexural isostatic response of the African plate to sediment transfers due to Meso-Cenozoic erosion - deposition processes in order to extract the residual topography driven by mantle dynamics. Our work will be based on the reconstruction and subtraction of two continental-scale erosional-depositional surfaces of Eocene and Late Cretaceous ages and their offshore extensions. The first step of our project consists in computing crustal and lithospheric maps of the African plate considering its various crustal geological components (cratons, mobile belts, basins, rifts and passive margins of various ages and strengths). In order to consider these heterogeneities, we compute a 2D distribution of crustal densities and thermal parameters from geological data and use it as an input of our modeling. We combine elevation and geoid anomaly data using a thermal analysis, following the method of Fullea et al. (2007) in order to map crustal and lithospheric thicknesses. In this approach, we assume local isostasy and consider a four-layer model made of crust and lithospheric mantle plus seawater and asthenosphere. In addition, we compare our results with crustal thickness datasets compiled from bibliography, existing global models such as CRUST 1.0, and tomographic lithospheric models. The obtained crustal thicknesses range from 30 to 45km, with the thickest crust confined to the northern part of the West African Craton, the Kaapvaal craton, and the Congo cuvette. The crust in the East African Rift appears unrealistically thick (40-45 km) as it is not isotatically compensated, highlighting the dynamic effect of the African superswell. The thinnest crust (30-35km) follows a central East-West trend coinciding with Cretaceous rifts and the Cameroon volcanic line. Pan-African mobile belts yield intermediate values of ca. 35-40 km. The lithosphere reaches 250 km beneath cratons, but remains globally thin (ca. 150-180 km

GNSS Wave Glider: First results from Loch Ness and demonstration of its suitability for determining the marine geoid

Science.gov (United States)

Penna, N. T.; Morales Maqueda, M.; Williams, S. D.; Foden, P.; Martin, I.; Pugh, J.

2013-12-01

We report on a first deployment of a GNSS Wave Glider designed for precise, unmanned, autonomous, mobile self-propelled sea level and sea state measurement in the open ocean. The Wave Glider, equipped with a dual frequency GPS+GLONASS receiver, was deployed in Loch Ness, Scotland, autonomously travelling 32 km in a north-easterly direction along the length of the loch in 26 hours, propelled by energy generated from waves of typical amplitude only 100-150 mm and frequency on the order 0.5-1 Hz. The Wave Glider GNSS data were analysed using a post-processed kinematic GPS+GLONASS precise point positioning (PPP) approach, which were quality controlled using double difference GPS kinematic processing with respect to onshore reference stations at either end of the loch. The PPP heights of the loch's surface revealed a clear geoid gradient of about 30 mm/km (i.e. just under 1 m over the whole length of the loch), very similar to both the EGM2008 and OSGM02 geoid models, demonstrating the potential use of a GNSS Wave Glider for marine geoid determination. After applying a low pass filter, the GNSS heights showed local deviations from both EGM2008 and OSGM02, potentially caused by omission errors or a lack of gravity data over Loch Ness. In addition to dual frequency GNSS data, the Wave Glider also recorded inclinometer data, bathymetry, and surface currents, which, in combination with tide gauge and wind data, were used to further control and interpret the GNSS time series.

Global and regional seasonal variations of the geoid detected by GRACE

Czech Academy of Sciences Publication Activity Database

Kostelecký, J.; Bezděk, Aleš; Klokočník, Jaroslav

2013-01-01

Roč. 10, č. 3 (2013), s. 285-291 ISSN 1214-9705 R&D Projects: GA ČR GA13-36843S Grant - others:EU(XE) NTIS CZ1.05/1.1.00/02.0090 Institutional support: RVO:67985815 Keywords : GRACE mission * seasonal variations * geoid Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 0.667, year: 2013

Variation of Marine Geoid Due to Ocean Circulation and Sea Level Change

Science.gov (United States)

Chu, P. C.

2017-12-01

Sea level (S) change and ocean circulation largely affect the gravity field and in turns the marine geoid (N). Difference between the two, D = S - N, is the dynamic ocean topography (DOT), whose gradient represents the large-scale surface geostrophic circulations. Thus, temporal variability of marine geoid (δN) is caused by the sea level change (δS) and the DOT variation (δD), δN = δS - δD. Here, δS is identified from temporally varying satellite altimeter measures; δD is calculated from the change of DOT. For large-scale processes with conservation of potential vorticity, the geostrophic flows take minimum energy state. Based on that, a new elliptic equation is derived in this study to determine D. Here, H is the water depth; and (X, Y) are forcing functions calculated from the in-situ density. The well-posed elliptic equation is integrated numerically on 1o grids for the world oceans with the boundary values taken from the mean DOT (1993-2006) field at the NASA/JPL website: https://grace.jpl.nasa.gov/data/get-data/dynamic-ocean-typography/, the forcing function F calculated from the three-dimensional temperature and salinity of the NOAA National Centers for Environmental Information (NCEI) World Ocean Atlas 2013 version 2, and sea-floor topography (H) from the NOAA ETOPO5. The numerical solution compares reasonably well (relative root mean square difference of 0.09) with the NASA/JPL satellite observation of the difference between the time-averaged sea surface height and the geoid. In-situ ocean measurements of temperature, salinity, and velocity have also rapidly advanced such that the global ocean is now continuously monitored by near 4,000 free-drifting profiling floats (called Argo) from the surface to 2000 m depth with all data being relayed and made publicly available within hours after collection (http://www.argo.ucsd.edu/). This provides a huge database of temperature and salinity and in turns the forcing function F for the governing elliptic

Estimates of the topographic uplift of the Southern African Plateau from the African Superswell through petrologically-consistent thermo-chemical modelling of the geoid, SHF, Rayleigh and Love dispersion curves and MT data

Science.gov (United States)

Jones, Alan G.; Afonso, Juan Carlos; Fullea, Javier

2015-04-01

The deep mantle African Superswell is thought to cause up to 500 m of the uplift of the Southern African Plateau. We investigate this phenomenon through stochastic thermo-chemical inversion modelling of the geoid, surface heat flow, Rayleigh and Love dispersion curves and MT data, in a manner that is fully petrologically-consistent. We invert for a three layer crustal velocity, density and thermal structure, but assume the resistivity layering (based on prior inversion of the MT data alone). Inversions are performed using an improved Delayed Rejection and Adaptive Metropolis (DRAM) type Markov chain Monte Carlo (MCMC) algorithm. We demonstrate that a single layer lithosphere can fit most of the data, but not the MT responses. We further demonstrate that modelling the seismic data alone, without the constraint of requiring reasonable oxide chemistry or of fitting the geoid, permits wildly acceptable elevations and with very poorly defined lithosphere-asthenosphere boundary (LAB). We parameterise the lithosphere into three layers, and bound the permitted oxide chemistry of each layer consistent with known chemical layering. We find acceptable models, from 5 million tested in each case, that fit all responses and yield a posteriori elevation distributions centred on 900-950 m, suggesting dynamic support from the lower mantle of some 400 m.

Tandem Gravimetric and Volumetric Apparatus for Methane Sorption Measurements

Science.gov (United States)

Burress, Jacob; Bethea, Donald

Concerns about global climate change have driven the search for alternative fuels. Natural gas (NG, methane) is a cleaner fuel than gasoline and abundantly available due to hydraulic fracturing. One hurdle to the adoption of NG vehicles is the bulky cylindrical storage vessels needed to store the NG at high pressures (3600 psi, 250 bar). The adsorption of methane in microporous materials can store large amounts of methane at low enough pressures for the allowance of conformable, ``flat'' pressure vessels. The measurement of the amount of gas stored in sorbent materials is typically done by measuring pressure differences (volumetric, manometric) or masses (gravimetric). Volumetric instruments of the Sievert type have uncertainties that compound with each additional measurement. Therefore, the highest-pressure measurement has the largest uncertainty. Gravimetric instruments don't have that drawback, but can have issues with buoyancy corrections. An instrument will be presented with which methane adsorption measurements can be performed using both volumetric and gravimetric methods in tandem. The gravimetric method presented has no buoyancy corrections and low uncertainty. Therefore, the gravimetric measurements can be performed throughout an entire isotherm or just at the extrema to verify the results from the volumetric measurements. Results from methane sorption measurements on an activated carbon (MSC-30) and a metal-organic framework (Cu-BTC, HKUST-1, MOF-199) will be shown. New recommendations for calculations of gas uptake and uncertainty measurements will be discussed.

An estimation of the height system bias parameter N (0) using least squares collocation from observed gravity and GPS-levelling data

DEFF Research Database (Denmark)

Sadiq, Muhammad; Tscherning, Carl C.; Ahmad, Zulfiqar

2009-01-01

This paper deals with the analysis of gravity anomaly and precise levelling in conjunction with GPS-Levelling data for the computation of a gravimetric geoid and an estimate of the height system bias parameter N-o for the vertical datum in Pakistan by means of least squares collocation technique...... covariance parameters has facilitated to achieve gravimetric height anomalies in a global geocentric datum. Residual terrain modeling (RTM) technique has been used in combination with the EGM96 for the reduction and smoothing of the gravity data. A value for the bias parameter N-o has been estimated...... with reference to the local GPS-Levelling datum that appears to be 0.705 m with 0.07 m mean square error. The gravimetric height anomalies were compared with height anomalies obtained from GPS-Levelling stations using least square collocation with and without bias adjustment. The bias adjustment minimizes...

Petrologically-constrained thermo-chemical modelling of cratonic upper mantle consistent with elevation, geoid, surface heat flow, seismic surface waves and MT data

Science.gov (United States)

Jones, A. G.; Afonso, J. C.

2015-12-01

The Earth comprises a single physio-chemical system that we interrogate from its surface and/or from space making observations related to various physical and chemical parameters. A change in one of those parameters affects many of the others; for example a change in velocity is almost always indicative of a concomitant change in density, which results in changes to elevation, gravity and geoid observations. Similarly, a change in oxide chemistry affects almost all physical parameters to a greater or lesser extent. We have now developed sophisticated tools to model/invert data in our individual disciplines to such an extent that we are obtaining high resolution, robust models from our datasets. However, in the vast majority of cases the different datasets are modelled/inverted independently of each other, and often even without considering other data in a qualitative sense. The LitMod framework of Afonso and colleagues presents integrated inversion of geoscientific data to yield thermo-chemical models that are petrologically consistent and constrained. Input data can comprise any combination of elevation, geoid, surface heat flow, seismic surface wave (Rayleigh and Love) data and receiver function data, and MT data. The basis of LitMod is characterization of the upper mantle in terms of five oxides in the CFMAS system and a thermal structure that is conductive to the LAB and convective along the adiabat below the LAB to the 410 km discontinuity. Candidate solutions are chosen from prior distributions of the oxides. For the crust, candidate solutions are chosen from distributions of crustal layering, velocity and density parameters. Those candidate solutions that fit the data within prescribed error limits are kept, and are used to establish broad posterior distributions from which new candidate solutions are chosen. Examples will be shown of application of this approach fitting data from the Kaapvaal Craton in South Africa and the Rae Craton in northern Canada. I

Zirconium determination in refractories (gravimetric method)

International Nuclear Information System (INIS)

Capiotto, N.; Narahashi, Y.; Perish, P.G.; Souza, J.R. de

1991-01-01

A gravimetric method for zirconium determination in refractories is described. X-ray fluorescence analysis is also employed in this experiment and considerations about interfering elements are presented. (M.V.M.)

To what extent can aerosol water explain the discrepancy between model calculated and gravimetric PM10 and PM2.5?

Directory of Open Access Journals (Sweden)

S. G. Tsyro

2005-01-01

Full Text Available Inter-comparisons of European air quality models show that regional transport models, including the EMEP (Co-operative Programme for monitoring and evaluation of the long-range transmission of air pollutants in Europe aerosol model, tend to underestimate the observed concentrations of PM10 and PM2.5. Obviously, an accurate representation of the individual aerosol constituents is a prerequisite for adequate calculation of PM concentrations. On the other hand, available measurements on the chemical characterization of ambient particles reveal that full chemical PM mass closure is rarely achieved. The fraction unaccounted for by chemical analysis can comprise as much as 30-40% of gravimetric PM10 or PM2.5 mass. The unaccounted PM mass can partly be due to non-C atoms in organic aerosols and/or due to sampling and measurement artefacts. Moreover, a part of the unaccounted PM mass is likely to consist of water associated with particles. Thus, the gravimetrically measured particle mass does not necessarily represent dry PM10 and PM2.5 mass. This is thought to be one of the reasons for models under-prediction of observed PM, if calculated dry PM10 and PM2.5 concentrations are compared with measurements. The EMEP aerosol model has been used to study to what extent particle-bound water can explain the chemically unidentified PM mass in filter-based particle samples. Water content of PM2.5 and PM10 has been estimated with the model for temperature 20°C and relative humidity 50%, which are conditions required for equilibration of dust-loaded filters according to the Reference method recommended by the European Committee for Standardization (CEN. Model calculations for Europe show that, depending on particle composition, particle-bound water constitutes 20-35% of the annual mean PM10 and PM2.5 concentrations, which is consistent with existing experimental estimates. At two Austrian sites, in Vienna and Streithofen, where daily measurements of PM2.5 mass

Combined Gravimetric-Seismic Crustal Model for Antarctica

Science.gov (United States)

Baranov, Alexey; Tenzer, Robert; Bagherbandi, Mohammad

2018-01-01

The latest seismic data and improved information about the subglacial bedrock relief are used in this study to estimate the sediment and crustal thickness under the Antarctic continent. Since large parts of Antarctica are not yet covered by seismic surveys, the gravity and crustal structure models are used to interpolate the Moho information where seismic data are missing. The gravity information is also extended offshore to detect the Moho under continental margins and neighboring oceanic crust. The processing strategy involves the solution to the Vening Meinesz-Moritz's inverse problem of isostasy constrained on seismic data. A comparison of our new results with existing studies indicates a substantial improvement in the sediment and crustal models. The seismic data analysis shows significant sediment accumulations in Antarctica, with broad sedimentary basins. According to our result, the maximum sediment thickness in Antarctica is about 15 km under Filchner-Ronne Ice Shelf. The Moho relief closely resembles major geological and tectonic features. A rather thick continental crust of East Antarctic Craton is separated from a complex geological/tectonic structure of West Antarctica by the Transantarctic Mountains. The average Moho depth of 34.1 km under the Antarctic continent slightly differs from previous estimates. A maximum Moho deepening of 58.2 km under the Gamburtsev Subglacial Mountains in East Antarctica confirmed the presence of deep and compact orogenic roots. Another large Moho depth in East Antarctica is detected under Dronning Maud Land with two orogenic roots under Wohlthat Massif (48-50 km) and the Kottas Mountains (48-50 km) that are separated by a relatively thin crust along Jutulstraumen Rift. The Moho depth under central parts of the Transantarctic Mountains reaches 46 km. The maximum Moho deepening (34-38 km) in West Antarctica is under the Antarctic Peninsula. The Moho depth minima in East Antarctica are found under the Lambert Trench (24

Zirconium determination in refractories (gravimetric method)

International Nuclear Information System (INIS)

Capiotto, N.; Narahashi, Y.; Perish, C.G.; Souza, J.R.

1991-01-01

The zirconium determination in refractories is described, consisting in two separation methods for eliminating the interferences. The formatted product is calcined at 1100 0 C and determined gravimetrically as Zr P z 07. (author)

Gravimetric and titrimetric methods of analysis

International Nuclear Information System (INIS)

Rives, R.D.; Bruks, R.R.

1983-01-01

Gravimetric and titrimetric methods of analysis are considered. Methods of complexometric titration are mentioned, as well as methods of increasing sensitivity in titrimetry. Gravimetry and titrimetry are applied during analysis for traces of geological materials

Gravimetric gas determinations for volume calibration

International Nuclear Information System (INIS)

Gibbs, P.W.

1991-01-01

Gravimetric measurements of gases is one of the methods available for calibrating gas volumes. By inputting a known quantity of gas and measuring the resulting pressure and temperature, the system volume can be calculated using gas law principles. Historically, this method has been less accurate due to the difficulty in the mass determination. This difficulty comes from several sources. Two examples are the large tare weight of the gas container relative to the weight of gas and the external volume of the gas container relative to the standards. The application of a gravimetric gas determination to tank volume calibrations at the savannah River Site is discussed. Mass determinations on a 25,00 gram gas container were such that a 1500 gram quantity of gas was routinely determined to within ±0.2 gram at the 99% confidence level. In this paper the weighting design and the methods used to address the difficulties of the mass determination are detailed

Estimation of the internal structure of Trans-Mexican volcanic belt by gravimetric data

International Nuclear Information System (INIS)

Flores R, J.H.

1994-01-01

The regional gravimetric data of Trans-Mexican volcanic belt and surroundings, has been analyzed in order to estimate the depth of its internal structure. The short profiles with N-S orientation give a model of four shells with an average depth in the rank 24, 34, 56 and 83 kilometers. Only the profiles included between 97 West degrees to 102 West degrees give a depth of crust larger than the rest of the profiles with the same orientation. This profiles are associated with that of the Valleys of Toluca, D.F. and Puebla where the maximum crust thickness was estimated. The 3 long profiles with S-W orientation, give a model of 3 shells. The tendency of the first shell has a cortical thickness of 38 kilometers in the latitude of 18 North degrees. This tendency to increase the depth in the crust is associated with the minimum gravimetric in the map of Bouguer anomaly. (Author)

Comparison of Potentiometric and Gravimetric Methods for Determination of O/U Ratio

International Nuclear Information System (INIS)

Farida; Windaryati, L; Putro Kasino, P

1998-01-01

Comparison of determination O/U ratio by using potentiometric and gravimetric methods has been done. Those methods are simple, economical and having high precision and accuracy. Determination O/U ratio for UO 2 powder using potentiometric is carried out by adopting the davies-gray method. This technique is based on the redox reaction of uranium species such as U(IV) and U(VI). In gravimetric method,the UO 2 power as a sample is calcined at temperature of 900 C, and the weight of the sample is measured after calcination process. The t-student test show that there are no different result significantly between those methods. However, for low concentration in the sample the potentiometric method has a highed precision and accuracy compare to the gravimetric method. O/U ratio obtained is 2.00768 ± 0,00170 for potentiometric method 2.01089 ± 0,02395 for gravimetric method

Combination volumetric and gravimetric sorption instrument for high accuracy measurements of methane adsorption

Science.gov (United States)

Burress, Jacob; Bethea, Donald; Troub, Brandon

2017-05-01

The accurate measurement of adsorbed gas up to high pressures (˜100 bars) is critical for the development of new materials for adsorbed gas storage. The typical Sievert-type volumetric method introduces accumulating errors that can become large at maximum pressures. Alternatively, gravimetric methods employing microbalances require careful buoyancy corrections. In this paper, we present a combination gravimetric and volumetric system for methane sorption measurements on samples between ˜0.5 and 1 g. The gravimetric method described requires no buoyancy corrections. The tandem use of the gravimetric method allows for a check on the highest uncertainty volumetric measurements. The sources and proper calculation of uncertainties are discussed. Results from methane measurements on activated carbon MSC-30 and metal-organic framework HKUST-1 are compared across methods and within the literature.

Gravity model development for TOPEX/POSEIDON: Joint gravity models 1 and 2

Science.gov (United States)

Nerem, R. S.; Lerch, F. J.; Marshall, J. A.; Pavlis, E. C.; Putney, B. H.; Tapley, B. D.; Eanes, R. J.; Ries, J. C.; Schutz, B. E.; Shum, C. K.

1994-01-01

The TOPEX/POSEIDON (T/P) prelaunch Joint Gravity Model-1 (JGM-1) and the postlaunch JGM-2 Earth gravitational models have been developed to support precision orbit determination for T/P. Each of these models is complete to degree 70 in spherical harmonics and was computed from a combination of satellite tracking data, satellite altimetry, and surface gravimetry. While improved orbit determination accuracies for T/P have driven the improvements in the models, the models are general in application and also provide an improved geoid for oceanographic computations. The postlaunch model, JGM-2, which includes T/P satellite laser ranging (SLR) and Doppler orbitography and radiopositioning integrated by satellite (DORIS) tracking data, introduces radial orbit errors for T/P that are only 2 cm RMS with the commission errors of the marine geoid for terms to degree 70 being +/- 25 cm. Errors in modeling the nonconservative forces acting on T/P increase the total radial errors to only 3-4 cm root mean square (RMS), a result much better than premission goals. While the orbit accuracy goal for T/P has been far surpassed geoid errors still prevent the absolute determination of the ocean dynamic topography for wavelengths shorter than about 2500 km. Only a dedicated gravitational field satellite mission will likely provide the necessary improvement in the geoid.

Gravimetric method for the determination of diclofenac in pharmaceutical preparations.

Science.gov (United States)

Tubino, Matthieu; De Souza, Rafael L

2005-01-01

A gravimetric method for the determination of diclofenac in pharmaceutical preparations was developed. Diclofenac is precipitated from aqueous solution with copper(II) acetate in pH 5.3 (acetic acid/acetate buffer). Sample aliquots had approximately the same quantity of the drug content in tablets (50 mg) or in ampules (75 mg). The observed standard deviation was about +/- 2 mg; therefore, the relative standard deviation (RSD) was approximately 4% for tablet and 3% for ampule preparations. The results were compared with those obtained with the liquid chromatography method recommended in the United States Pharmacopoeia using the statistical Student's t-test. Complete agreement was observed. It is possible to obtain more precise results using higher aliquots, for example 200 mg, in which case the RSD falls to 1%. This gravimetric method, contrary to what is expected for this kind of procedure, is relatively fast and simple to perform. The main advantage is the absolute character of the gravimetric analysis.

Combined Colorimetric and Gravimetric CMUT Sensor for Detection of Phenylacetone

DEFF Research Database (Denmark)

Mølgaard, Mathias Johannes Grøndahl; Laustsen, Milan; Thygesen, Ida Lysgaard

2017-01-01

The detection of phenylacetone is of interest as it is a common precursor for the synthesis of (meth)amphetamine. Resonant gravimetric sensors can be used to detect the mass and hereby the concentration of a gas while colorimetric arrays typically have an exceptional selectivity to the target...... analyte if the right colorimetric dyes are chosen. We present a sensor system consisting of a Capacitive Micromachined Ultrasonic Transducer (CMUT) and a colorimetric array for detection of phenylacetone. The CMUT is used as a resonant gravimetric gas sensor where the resonance frequency shift due to mass...

Modelación del geoide en presas de colas de la región minera de Moa

Directory of Open Access Journals (Sweden)

Yordanis Esteban Batista-Legrá

2014-12-01

Full Text Available El presente trabajo tuvo el propósito de determinar el modelo del geoide en las presas de colas de la región minera de Moa, con el fin de obtener las alturas de puntos sobre la superficie del terreno con la exactitud que requiere el movimiento de tierras, para lo cual fueron empleados los Sistemas de Posicionamiento Global (GPS. Se aplicaron métodos de Topografía Minera, Geodesia Física, Hidrografía, Oceanografía, Cartografía Digital y Modelación y se integraron diferentes softwares para procesar la información obtenida en los experimentos. Como resultado se ofrece un nuevo método para determinar el modelo del geoide, la implementación de un Sistema de Información Geográfica (SIG para la modelación y un estudio del nivel medio del mar en la costa de Moa

Gravimetric Analysis of Uranium in Yellow Cake

International Nuclear Information System (INIS)

Srinuttrakul, Wannee; Jantha, Suwat

2007-08-01

Full text: The gravimetric analysis of uranium in yellow cake is composed of several stages. The analysis takes a long time, which is the disadvantage of this method. However, this gravimetric method provides accurate result for determining the major content of sample. Uranium is the main composition of yellow cake, while Thorium, rare earths and other elements are minor and trace elements. In this work, anion exchange resin was used to separate uranium from other elements to yield highly pure uranium suitable for precipitation. This pure uranium was burnt to U3O8, a form that is stable enough to be weighed. From the optimal condition, the recovery of U3O8 after separating uranium from rare earths and iron is 99.85 ± 0.21%. The application of anion exchange separation was used to analyze uranium in yellow cake obtained from monazite digestion process. It was found that U3O8 in yellow cake is 78.85 ± 2.03%

Measuring intestinal fluid transport in vitro: Gravimetric method versus non-absorbable marker.

Science.gov (United States)

Whittamore, Jonathan M; Genz, Janet; Grosell, Martin; Wilson, Rod W

2016-04-01

The gut sac is a long-standing, widely used in vitro preparation for studying solute and water transport, and calculation of these fluxes requires an accurate assessment of volume. This is commonly determined gravimetrically by measuring the change in mass over time. While convenient this likely under-estimates actual net water flux (Jv) due to tissue edema. We evaluated whether the popular in vivo volume marker [(14)C]-PEG 4000, offers a more representative measure of Jvin vitro. We directly compared these two methods in five teleost species (toadfish, flounder, rainbow trout, killifish and tilapia). Net fluid absorption by the toadfish intestine based on PEG was significantly higher, by almost 4-fold, compared to gravimetric measurements, compatible with the latter under-estimating Jv. Despite this, PEG proved inconsistent for all of the other species frequently resulting in calculation of net secretion, in contrast to absorption seen gravimetrically. Such poor parallelism could not be explained by the absorption of [(14)C]-PEG (typically gravimetric method therefore remains the most reliable measure of Jv and we urge caution in the use of PEG as a volume marker. Copyright © 2016 Elsevier Inc. All rights reserved.

A Comparative Analysis of Seismological and Gravimetric Crustal Thicknesses below the Andean Region with Flat Subduction of the Nazca Plate

Directory of Open Access Journals (Sweden)

Mario E. Gimenez

2009-01-01

Full Text Available A gravimetric study was carried out in a region of the Central Andean Range between 28∘ and 32∘ south latitudes and from 72∘ and 66∘ west longitudes. The seismological and gravimetrical Moho models were compared in a sector which coincides with the seismological stations of the CHARGE project. The comparison reveals discrepancies between the gravity Moho depths and those obtained from seismological investigations (CHARGE project, the latter giving deeper values than those resulting from the gravimetric inversion. These discrepancies are attenuated when the positive gravimetric effect of the Nazca plate is considered. Nonetheless, a small residuum of about 5 km remains beneath the Cuyania terrane region, to the east of the main Andean chain. This residuum could be gravimetrically justified if the existence of a high density or eclogitized portion of the lower crust is considered. This result differed from the interpretations from Project “CHARGE” which revealed that the entire inferior crust extending from the Precordillera to the occidental “Sierras Pampeanas” could be “eclogitized”. In this same sector, we calculated the effective elastic thickness (Te of the crust. These results indicated an anomalous value of Te = 30 km below the Cuyania terrane. This is further conclusive evidence of the fact that the Cuyania terrane is allochthonous, for which also geological evidences exist.

Zero drift and solid Earth tide extracted from relative gravimetric data with principal component analysis

OpenAIRE

Hongjuan Yu; Jinyun Guo; Jiulong Li; Dapeng Mu; Qiaoli Kong

2015-01-01

Zero drift and solid Earth tide corrections to static relative gravimetric data cannot be ignored. In this paper, a new principal component analysis (PCA) algorithm is presented to extract the zero drift and the solid Earth tide, as signals, from static relative gravimetric data assuming that the components contained in the relative gravimetric data are uncorrelated. Static relative gravity observations from Aug. 15 to Aug. 23, 2014 are used as statistical variables to separate the signal and...

Lateral variation in upper mantle temperature and composition beneath mid-ocean ridges inferred from shear-wave propagation, geoid, and bathymetry. Ph.D. Thesis

Science.gov (United States)

Sheehan, Anne Francis

1991-01-01

Resolution of both the extent and mechanism of lateral heterogeneity in the upper mantle constraints the nature and scales of mantle convection. Oceanic regions are of particular interest as they are likely to provide the closest glimpse at the patterns of temperature anomalies and convective flow in the upper mantle because of their young age and simple crustal structure relative to continental regions. Lateral variations were determined in the seismic velocity and attenuation structure of the lithosphere and astenosphere beneath the oceans, and these seismological observations were combined with the data and theory of geoid and bathymetry anomalies in order to test and improve current models for seafloor spreading and mantle convection. Variations were determined in mantle properties on a scale of about 1000 km, comparable to the thickness of the upper mantle. Seismic velocity, geoid, and bathymetry anomalies are all sensitive to variations in upper mantle density, and inversions were formulated to combine quantitatively these different data and to search for a common origin. Variations in mantle density can be either of thermal or compositional origin and are related to mantle convection or differentiation.

40 CFR 1065.290 - PM gravimetric balance.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 32 2010-07-01 2010-07-01 false PM gravimetric balance. 1065.290... balance. (a) Application. Use a balance to weigh net PM on a sample medium for laboratory testing. (b) Component requirements. We recommend that you use a balance that meets the specifications in Table 1 of...

A gravimetric simplified method for nucleated marrow cell counting using an injection needle.

Science.gov (United States)

Saitoh, Toshiki; Fang, Liu; Matsumoto, Kiyoshi

2005-08-01

A simplified gravimetric marrow cell counting method for rats is proposed for a regular screening method. After fresh bone marrow was aspirated by an injection needle, the marrow cells were suspended in carbonate buffered saline. The nucleated marrow cell count (NMC) was measured by an automated multi-blood cell analyzer. When this gravimetric method was applied to rats, the NMC of the left and right femurs had essentially identical values due to careful handling. The NMC at 4 to 10 weeks of age in male and female Crj:CD(SD)IGS rats was 2.72 to 1.96 and 2.75 to 1.98 (x10(6) counts/mg), respectively. More useful information for evaluation could be obtained by using this gravimetric method in addition to myelogram examination. However, some difficulties with this method include low NMC due to blood contamination and variation of NMC due to handling. Therefore, the utility of this gravimetric method for screening will be clarified by the accumulation of the data on myelotoxicity studies with this method.

Lowest Astronomical Tide in the North Sea derived from a vertically referenced shallow water model, and an assessment of its suggested sense of safety

NARCIS (Netherlands)

Slobbe, D.C.; Klees, R.; Verlaan, M.; Dorst, L.; Gerritsen, H.

2012-01-01

In this study, LAT will be modeled relative to a geoid, after which the ellipsoidal heights of LAT will be obtained by adding geoid heights to the modeled LAT values. The use of a geoid instead of MSL has the advantage that the former can be realized everywhere and does not leave a gap along the

Comparison of macro-gravimetric and micro-colorimetric lipid determination methods.

Science.gov (United States)

Inouye, Laura S; Lotufo, Guiherme R

2006-10-15

In order to validate a method for lipid analysis of small tissue samples, the standard macro-gravimetric method of Bligh-Dyer (1959) [E.G. Bligh, W.J. Dyer, Can. J. Biochem. Physiol. 37 (1959) 911] and a modification of the micro-colorimetric assay developed by Van Handel (1985) [E. Van Handel, J. Am. Mosq. Control Assoc. 1 (1985) 302] were compared. No significant differences were observed for wet tissues of two species of fish. However, limited analysis of wet tissue of the amphipod, Leptocheirusplumulosus, indicated that the Bligh-Dyer gravimetric method generated higher lipid values, most likely due to the inclusion of non-lipid materials. Additionally, significant differences between the methods were observed with dry tissues, with the micro-colorimetric method consistently reporting calculated lipid values greater than as reported by the gravimetric method. This was most likely due to poor extraction of dry tissue in the standard Bligh-Dyer method, as no significant differences were found when analyzing a single composite extract. The data presented supports the conclusion that the micro-colorimetric method described in this paper is accurate, rapid, and minimizes time and solvent use.

On the equivalence of spherical splines with least-squares collocation and Stokes's formula for regional geoid computation

Science.gov (United States)

Ophaug, Vegard; Gerlach, Christian

2017-11-01

This work is an investigation of three methods for regional geoid computation: Stokes's formula, least-squares collocation (LSC), and spherical radial base functions (RBFs) using the spline kernel (SK). It is a first attempt to compare the three methods theoretically and numerically in a unified framework. While Stokes integration and LSC may be regarded as classic methods for regional geoid computation, RBFs may still be regarded as a modern approach. All methods are theoretically equal when applied globally, and we therefore expect them to give comparable results in regional applications. However, it has been shown by de Min (Bull Géod 69:223-232, 1995. doi: 10.1007/BF00806734) that the equivalence of Stokes's formula and LSC does not hold in regional applications without modifying the cross-covariance function. In order to make all methods comparable in regional applications, the corresponding modification has been introduced also in the SK. Ultimately, we present numerical examples comparing Stokes's formula, LSC, and SKs in a closed-loop environment using synthetic noise-free data, to verify their equivalence. All agree on the millimeter level.

Comparison of remove-compute-restore and least squares modification of Stokes' formula techniques to quasi-geoid determination over the Auvergne test area

DEFF Research Database (Denmark)

Yildiz, H.; Forsberg, René; Ågren, J.

2012-01-01

The remove-compute-restore (RCR) technique for regional geoid determination implies that both topography and low-degree global geopotential model signals are removed before computation and restored after Stokes' integration or Least Squares Collocation (LSC) solution. The Least Squares Modification...... area. All methods showed a reasonable agreement with GPS-levelling data, in the order of a 3-3.5 cm in the central region having relatively smooth topography, which is consistent with the accuracies of GPS and levelling. When a 1-parameter fit is used, the FFT method using kernel modification performs...

Reduction Of Gravimetric Data Using An Integrated Computer ...

African Journals Online (AJOL)

The rigour of gravimetric data collection, and the non-availability of comprehensive data reduction software that takes care of local peculiarities, have always constituted hindrance to the application of the gravity method of geophysical studies. However, in recent time, the importance of the gravity method in mineral ...

Technical note: Comparison of metal-on-metal hip simulator wear measured by gravimetric, CMM and optical profiling methods

Science.gov (United States)

Alberts, L. Russell; Martinez-Nogues, Vanesa; Baker Cook, Richard; Maul, Christian; Bills, Paul; Racasan, R.; Stolz, Martin; Wood, Robert J. K.

2018-03-01

Simulation of wear in artificial joint implants is critical for evaluating implant designs and materials. Traditional protocols employ the gravimetric method to determine the loss of material by measuring the weight of the implant components before and after various test intervals and after the completed test. However, the gravimetric method cannot identify the location, area coverage or maximum depth of the wear and it has difficulties with proportionally small weight changes in relatively heavy implants. In this study, we compare the gravimetric method with two geometric surface methods; an optical light method (RedLux) and a coordinate measuring method (CMM). We tested ten Adept hips in a simulator for 2 million cycles (MC). Gravimetric and optical methods were performed at 0.33, 0.66, 1.00, 1.33 and 2 MC. CMM measurements were done before and after the test. A high correlation was found between the gravimetric and optical methods for both heads (R 2  =  0.997) and for cups (R 2  =  0.96). Both geometric methods (optical and CMM) measured more volume loss than the gravimetric method (for the heads, p  =  0.004 (optical) and p  =  0.08 (CMM); for the cups p  =  0.01 (optical) and p  =  0.003 (CMM)). Two cups recorded negative wear at 2 MC by the gravimetric method but none did by either the optical method or by CMM. The geometric methods were prone to confounding factors such as surface deformation and the gravimetric method could be confounded by protein absorption and backside wear. Both of the geometric methods were able to show the location, area covered and depth of the wear on the bearing surfaces, and track their changes during the test run; providing significant advantages to solely using the gravimetric method.

Crumpled Nitrogen-Doped Graphene for Supercapacitors with High Gravimetric and Volumetric Performances.

Science.gov (United States)

Wang, Jie; Ding, Bing; Xu, Yunling; Shen, Laifa; Dou, Hui; Zhang, Xiaogang

2015-10-14

Graphene is considered a promising electrochemical capacitors electrode material due to its high surface area and high electrical conductivity. However, restacking interactions between graphene nanosheets significantly decrease the ion-accessible surface area and impede electronic and ionic transfer. This would, in turn, severely hinder the realization of high energy density. Herein, we report a strategy for preparation of few-layer graphene material with abundant crumples and high-level nitrogen doping. The two-dimensional graphene nanosheets (CNG) feature high ion-available surface area, excellent electronic and ion transfer properties, and high packing density, permitting the CNG electrode to exhibit excellent electrochemical performance. In ionic liquid electrolyte, the CNG electrode exhibits gravimetric and volumetric capacitances of 128 F g(-1) and 98 F cm(-3), respectively, achieving gravimetric and volumetric energy densities of 56 Wh kg(-1) and 43 Wh L(-1). The preparation strategy described here provides a new approach for developing a graphene-based supercapacitor with high gravimetric and volumetric energy densities.

An Assessment of State-of-the-Art Mean Sea Surface and Geoid Models of the Arctic Ocean: Implications for Sea Ice Freeboard Retrieval

Science.gov (United States)

Skourup, Henriette; Farrell, Sinéad Louise; Hendricks, Stefan; Ricker, Robert; Armitage, Thomas W. K.; Ridout, Andy; Andersen, Ole Baltazar; Haas, Christian; Baker, Steven

2017-11-01

State-of-the-art Arctic Ocean mean sea surface (MSS) models and global geoid models (GGMs) are used to support sea ice freeboard estimation from satellite altimeters, as well as in oceanographic studies such as mapping sea level anomalies and mean dynamic ocean topography. However, errors in a given model in the high-frequency domain, primarily due to unresolved gravity features, can result in errors in the estimated along-track freeboard. These errors are exacerbated in areas with a sparse lead distribution in consolidated ice pack conditions. Additionally model errors can impact ocean geostrophic currents, derived from satellite altimeter data, while remaining biases in these models may impact longer-term, multisensor oceanographic time series of sea level change in the Arctic. This study focuses on an assessment of five state-of-the-art Arctic MSS models (UCL13/04 and DTU15/13/10) and a commonly used GGM (EGM2008). We describe errors due to unresolved gravity features, intersatellite biases, and remaining satellite orbit errors, and their impact on the derivation of sea ice freeboard. The latest MSS models, incorporating CryoSat-2 sea surface height measurements, show improved definition of gravity features, such as the Gakkel Ridge. The standard deviation between models ranges 0.03-0.25 m. The impact of remaining MSS/GGM errors on freeboard retrieval can reach several decimeters in parts of the Arctic. While the maximum observed freeboard difference found in the central Arctic was 0.59 m (UCL13 MSS minus EGM2008 GGM), the standard deviation in freeboard differences is 0.03-0.06 m.

Gravimetric and profilometric measurements of the ablation rates of photosensitive polymers at different wavelengths

International Nuclear Information System (INIS)

Dumont, Th.; Bischofberger, R.; Lippert, T.; Wokaun, A.

2005-01-01

The ablation rates of two polyimides (PMDA and DurimidTM) and one triazene polymer were studied by gravimetric (quartz microbalance) and profilometric (profilometer) methods at irradiation wavelengths of 193, 248 and 308 nm. The ablation rates determined by the two methods are discussed in the context of the absorption behavior of the materials. Furthermore, the consistence of the two experimental methods is discussed for the ablation rates of DurimidTM and the triazene polymer. The gravimetric measurements revealed a good correlation between the ablation rate and the absorption properties of the examined materials. The comparison of the gravimetric and the profilometric measurements suggest a significant mass removal, e.g. by formation of gaseous products, prior to the detection of changes in the surface morphology

A study on improvement of measurement capability for gravimetric flowmeter calibrator

International Nuclear Information System (INIS)

Lee, Dong Keun; Park, Jong Ho

2009-01-01

The calibration of flowmeter is a very important procedure to set up traceability from the national or international standards. The uncertainty of flow measurement defines reliability for measurement results. The uncertainty of gravimetric method combines uncertainties of each independent variable, including mass, time, water density, air density and the density of dead weight. In this study, it has been found that the uncertainties of mass and time measurement in the gravimetric method have dominant influence on the total measurement uncertainty. After improvements of a constant head tank and a diverter, the best measurement capability for K-water's calibration facility has been reached less than 0.1%.

Quartz analysis in gravimetric sampling

International Nuclear Information System (INIS)

Rex, D.A.

1990-01-01

An overview of the methods employed in the assessment of quartz exposure is provided. The principles and some of the problems associated with each method is discussed. The methods reviewed include wet chemical methods, X-ray diffraction and infrared absorption of which the latter two methods are deemed appropriate for analysing quartz on personal gravimetric collected samples. The implications of combining area samples collected over a six month period, and performing only a single quartz analysis rather than separate analyses, are considered. Finally, various options open to mines with regard to their involvement with quartz analysis are also briefly discussed. 35 refs., 6 figs., 1 tab

Comparison of the gravimetric, phenol red, and 14C-PEG-3350 methods to determine water absorption in the rat single-pass intestinal perfusion model

OpenAIRE

Sutton, Steven C.; Rinaldi, M. T. S.; Vukovinsky, K. E.

2001-01-01

This study was undertaken to determine whether the gravimetric method provided an accurate measure of water flux correction and to compare the gravimetric method with methods that employ nonabsorbed markers (eg, phenol red and 14C-PEG-3350). Phenol red, 14C-PEG-3350, and 4-[2-[[2-(6-amino-3-pyridinyl)-2-hydroxyethyl]amino]ethoxy]-methyl ester, (R)-benzene acetic acid (Compound I) were co-perfused in situ through the jejunum of 9 anesthetized rats (single-pass intestinal perfusion [SPIP]). Wat...

Application of neural network technique to determine a corrector surface for global geopotential model using GPS/levelling measurements in Egypt

Science.gov (United States)

Elshambaky, Hossam Talaat

2018-01-01

Owing to the appearance of many global geopotential models, it is necessary to determine the most appropriate model for use in Egyptian territory. In this study, we aim to investigate three global models, namely EGM2008, EIGEN-6c4, and GECO. We use five mathematical transformation techniques, i.e., polynomial expression, exponential regression, least-squares collocation, multilayer feed forward neural network, and radial basis neural networks to make the conversion from regional geometrical geoid to global geoid models and vice versa. From a statistical comparison study based on quality indexes between previous transformation techniques, we confirm that the multilayer feed forward neural network with two neurons is the most accurate of the examined transformation technique, and based on the mean tide condition, EGM2008 represents the most suitable global geopotential model for use in Egyptian territory to date. The final product gained from this study was the corrector surface that was used to facilitate the transformation process between regional geometrical geoid model and the global geoid model.

3D inversion and modeling of magnetic and gravimetric data characterizing the geophysical anomaly source in Pratinha I in the southeast of Brazil

Science.gov (United States)

Louro, Vinicius Hector Abud; Mantovani, Marta Silvia Maria

2012-05-01

The Alto do Paranaíba Igneous Province (APIP) is known for its great mineral exploratory interest in phosphates, niobium, titanium, and diamonds, among others. In the years of 2005 and 2006, the Economic Development Company of Minas Gerais (CODEMIG — http://www.comig.com.br/) performed an airborne magnetic survey over the portion of this igneous province which belongs to Minas Gerais state, denominated Area 7. This survey revealed at the coordinates (19°45'S, 46°10'W) a tripolar anomaly here referred as Pratinha I. This anomaly does not present evidences of outcropping or topographic remodeling. So, boreholes or studies over its sources make the geophysical methods the best and less expensive solution for studying the body in its subsurface. Besides, two gravimetric ground surveys were performed in 2009 and 2010, confirming the existence of a density contrast over the region of the magnetic anomaly. Therefore, through the magnetometry and gravimetry processing, 3D modeling and inversions, it was possible to estimate the geometry, density and magnetic susceptibility, which when analyzed with the regional geology, enabled the proposition of an igneous intrusion of probable alkaline or kamafugitic composition to justify the gravimetric and magnetic response in the region.

Spectrophotometric, potentiometric, and gravimetric determination of lanthanides with peri-dihydroxynaphthindenone

International Nuclear Information System (INIS)

Hassan, S.S.M.; Mahmoud, W.H.

1982-01-01

Sensitive and reasonably selective methods are described for the spectrophotometric, potentiometric, and gravimetric determination of lanthanides using peri-dihydroxynaphthindenone as a novel chromogenic and precipitating reagent. The reagent forms a stable 1:2 (metal:reagent) type of complex with light lanthanides at pH 2-7 in 1:1 ethanol-water mixture. Low metal concentrations ( 4 L mol -1 cm -1 ) which obey Beer's law. Quantitative precipitation of the complexes from metal solutions of concentrations > 100 μg/mL permits both gravimetric quantitation by igniting the precipitates to the metal oxides and potentiometric titration of the excess reagent. Results with an average recovery of 98% (standard deviation 0.7%) are obtainable for 0.1 μg to 200 mg of all light lanthanides. Many foreign ions naturally occurring or frequently associated with lanthanides do not interfere or can be tolerated

Uncertainty Quantification and Global Sensitivity Analysis of Subsurface Flow Parameters to Gravimetric Variations During Pumping Tests in Unconfined Aquifers

Science.gov (United States)

Maina, Fadji Zaouna; Guadagnini, Alberto

2018-01-01

We study the contribution of typically uncertain subsurface flow parameters to gravity changes that can be recorded during pumping tests in unconfined aquifers. We do so in the framework of a Global Sensitivity Analysis and quantify the effects of uncertainty of such parameters on the first four statistical moments of the probability distribution of gravimetric variations induced by the operation of the well. System parameters are grouped into two main categories, respectively, governing groundwater flow in the unsaturated and saturated portions of the domain. We ground our work on the three-dimensional analytical model proposed by Mishra and Neuman (2011), which fully takes into account the richness of the physical process taking place across the unsaturated and saturated zones and storage effects in a finite radius pumping well. The relative influence of model parameter uncertainties on drawdown, moisture content, and gravity changes are quantified through (a) the Sobol' indices, derived from a classical decomposition of variance and (b) recently developed indices quantifying the relative contribution of each uncertain model parameter to the (ensemble) mean, skewness, and kurtosis of the model output. Our results document (i) the importance of the effects of the parameters governing the unsaturated flow dynamics on the mean and variance of local drawdown and gravity changes; (ii) the marked sensitivity (as expressed in terms of the statistical moments analyzed) of gravity changes to the employed water retention curve model parameter, specific yield, and storage, and (iii) the influential role of hydraulic conductivity of the unsaturated and saturated zones to the skewness and kurtosis of gravimetric variation distributions. The observed temporal dynamics of the strength of the relative contribution of system parameters to gravimetric variations suggest that gravity data have a clear potential to provide useful information for estimating the key hydraulic

Accuracy criteria recommended for the certification of gravimetric coal-mine-dust samplers

International Nuclear Information System (INIS)

Bowman, J.D.; Bartley, D.L.; Breuer, G.M.; Doemeny, L.J.; Murdock, D.J.

1984-07-01

Procedures for testing bias and precision of gravimetric coal-mine-dust sampling units are reviewed. Performance criteria for NIOSH certification of personal coal-mine dust samplers are considered. The NIOSH criterion is an accuracy of 25% at the 95% confidence interval. Size distributions of coal-mine-dust are discussed. Methods for determining size distributions are described. Sampling and sizing methods are considered. Cyclone parameter estimation is discussed. Bias computations for general sampling units are noted. Recommended procedures for evaluating bias and precision of gravimetric coal mine dust personal samplers are given. The authors conclude that when cyclones are operated at lower rates, the NIOSH accuracy criteria can be met

Three years of high precision gravity measurements at the gravimetric station of Brasimone - Italy

Directory of Open Access Journals (Sweden)

G. Casula

1998-06-01

Full Text Available From August 1995 up to now, at the Enea Research Center of Brasimone, in the Italian Apennines between Bologna and Florence (Italy: 44º07'N, 11º.07'E, 890 m height, the superconducting gravimeter GWR model TT70 number T015 has been continuously recording the variation of the local gravity field, in the frame of the Global Geodynamics Project. The gravimetric laboratory, being a room of the disused nuclear power plant of Brasimone, is a very stable site, free from noise due to human activities. Data blocks of several months of continuous gravity records have been collected over a time span of three years, together with the meteorological data. The gravimeter has been calibrated at relative accuracy better than 0.3% with the aid of a mobile mass system, by imposed perturbations of the local gravity field and recording the gravimeter response. The results of this calibration technique were checked by two comparison experiments with absolute gravimeters performed during this period: the first, in May 1994 with the aid of the symmetrical rise and fall gravimeter of the Institute of Metrology Colonnetti of Turin, and the second in October 1997 involving an FG5 absolute gravimeter of the Institute de Physique du Globe of Strasbourg. The gravimeter signal was analysed to compute a high precision tidal model for Brasimone site. Starting from a set of gravimetric and atmospheric pressure data of high quality, relative to 46 months of observation, we performed the tidal analysis using Eterna 3.2 software to compute amplitudes, gravimetric factors and phases of the main waves of the Tamura catalogue. Finally a comparison experiment between two of the STS-1/VBB broadband seismometers of the MedNet project network and the gravity records relative to the Balleny Islands earthquake (March 25, 1998 were analysed to look for evidence of normal modes due to the free oscillations of the Earth.

Kampanje mjerenja apsolutnog i relativnog ubrzanja sile teže u „Osnovnoj gravimetrijskoj mreži Bosne i Hercegovine“ : Measurement campaign of absolute and relative gravity in "Basic gravimetric network of Bosnia and Herzegovina"

Directory of Open Access Journals (Sweden)

Hasumana Abaza

2014-12-01

Full Text Available Mjerenje apsolutnog ubrzanja sile Zemljine teže u Bosni i Hercegovini izvršeno je na četiri stanice, a u okviru projekta “Izgradnja kapaciteta za unapređenje zemljišne administracije i procedura u Bosni i Hercegovini“. Mjerenje relativnog ubrzanja sile Zemljine teže također je završeno u Osnovnoj gravimetrijskoj mreži BiH na 60 tačaka, te je izvršeno povezivanje sa stanicama na kojim je mjereno apsolutno ubrzanje sile teže. Do sada urađen posao je odlična osnova za nastavak radova na regionalnom gravimetrijskom premjeru na putu ka konačnom cilju određivanja geoida za teritoriju BiH. : Absolute gravity measurements in Bosnia and Herzegovina were carried out at four stations within the project "Capacity building for improving land administration and procedures in Bosnia and Herzegovina“ - CILAP. Relative gravity measurements were also completed in the primary gravimetric network of Bosnia and Herzegovina at 60 points, followed by connecting points with absolute gravity data. So far, completed work is an excellent basis for continuing on regional gravity measurements and determining the geoid for the territory of Bosnia and Herzegovina.

Offshore gravimetric and subsidence monitoring

Energy Technology Data Exchange (ETDEWEB)

Stenvold, Torkjell

2008-06-15

are discussed in Stenvold et al. (Chapter 2). A latitude dependence of the calibration scale factors of Scintrex gravimeters is shown for the first time. Chapter 5 contains the article 'Constraints on the in situ density of CO2 within the Utsira formation from time-lapse seafloor gravity measurements' by Nooner et al. (2007), published in the International Journal of Greenhouse Gas Control. In this article gravity measurements made on 30 seafloor stations above the CO2 bubble in 2002 and 2005 have been used to constrain the in-situ density of CO2 for models derived from seismic. The gravity responses of various numerical models are compared for the1999 to 2001 period. Note that time-lapse seismic for the 2002-2005 period was not available when this article was written. Chapter 6 contains the article 'Monitoring both gas production and CO2 injection at the Sleipner field using time-lapse gravimetry' by Alnes et al., submitted 29 February 2008 to Geophysics. This is a renewed analysis of the same gravity data as in the article by Nooner et al. (Chapter 5). Recently available 4D seismic, a more updated reservoir simulation model, and reprocessed gravity and pressure data give a new estimate of CO2 density. The observed gravity response between 2002 and 2005 from the underlying Ty Formation is shown for the first time. Chapter 7 contains the article 'Gravimetric monitoring of gas production from the Troll field' by Eiken et al., submitted 3 April 2008 to Geophysics. The gravity data is used to map and quantify water influx on Troll between 2002 and 2005. There is good agreement with well data and the amount of water influx agrees with material balance calculations. Chapter 8 contains the article 'Gravimetric monitoring of gas reservoir water influx' a combined flow- and gravity-modeling approach' by Stenvold et al., and was accepted for publication in January 2008 by Geophysics. It is to appear in an upcoming special section on

Gravimetric dust sampling for control purposes and occupational dust sampling.

CSIR Research Space (South Africa)

Unsted, AD

1997-02-01

Full Text Available Prior to the introduction of gravimetric dust sampling, konimeters had been used for dust sampling, which was largely for control purposes. Whether or not absolute results were achievable was not an issue since relative results were used to evaluate...

A rapid method to map the crustal and lithospheric thickness using elevation, geoid anomaly and thermal analysis. Application to the Gibraltar Arc System, Atlas Mountains and adjacent zones

Science.gov (United States)

Fullea, J.; Fernàndez, M.; Zeyen, H.; Vergés, J.

2007-02-01

We present a method based on the combination of elevation and geoid anomaly data together with thermal field to map crustal and lithospheric thickness. The main assumptions are local isostasy and a four-layered model composed of crust, lithospheric mantle, sea water and the asthenosphere. We consider a linear density gradient for the crust and a temperature dependent density for the lithospheric mantle. We perform sensitivity tests to evaluate the effect of the variation of the model parameters and the influence of RMS error of elevation and geoid anomaly databases. The application of this method to the Gibraltar Arc System, Atlas Mountains and adjacent zones reveals the presence of a lithospheric thinning zone, SW-NE oriented. This zone affects the High and Middle Atlas and extends from the Canary Islands to the eastern Alboran Basin and is probably linked with a similarly trending zone of thick lithosphere constituting the western Betics, eastern Rif, Rharb Basin, and Gulf of Cadiz. A number of different, even mutually opposite, geodynamic models have been proposed to explain the origin and evolution of the study area. Our results suggest that a plausible slab-retreating model should incorporate tear and asymmetric roll-back of the subducting slab to fit the present-day observed lithosphere geometry. In this context, the lithospheric thinning would be caused by lateral asthenospheric flow. An alternative mechanism responsible for lithospheric thinning is the presence of a hot magmatic reservoir derived from a deep ancient plume centred in the Canary Island, and extending as far as Central Europe.

Gravimetric determination of beryllium in the presence of transition metals

International Nuclear Information System (INIS)

Morozova, S.S.; Nikitina, L.V.; Dyatlova, N.M.; Serebryakova, G.V.; Vol'nyagina, A.N.

1976-01-01

A new organic reagent, nitrolotrimethylphosphonic acid (H 6 L), is proposed for gravimetric determination of beryllium. This complexone forms with Be hardly soluble complexes in a wide pH range. The separated complex has a composition Be 5 (HL) 2 x10H 2 O. To elucidate the possibility of determining Be in the presence of transition metals, often accompanying beryllium in alloys, interaction of cations of these metals with H 6 L at different pH has been studied potentiometrically. It has been established that at pH=1.1 in the presence of masking reagent (diethylentriaminopentacetic acid) Be can be determined when zinc, copper, chromium, cobalt, nickel, iron, manganese and cadmium are present. Gravimetric method of determining Be with the help of H 6 L has been developed. The weight form is obtained by drying the precipitate which reduces considerably the time of analysis and the error of determination

Gravimetric determination of the iodine number of carbon black

International Nuclear Information System (INIS)

Murphy, L.J. Jr.

1991-01-01

This paper discusses a gravimetric method for the determination of the iodine adsorption number of carbon black. It comprises determining the concentration of an accurately weighed iodine blank solution by adding a standardized titrant to the iodine solution until a titration endpoint is reached and determining the concentration of the iodine solution by accurately weighing the amount of the standardized titrant necessary to reach the endpoint, accurately weighing an amount of carbon black and adding an appropriate amount of an accurately weighed portion of the iodine solution, equilibrating the carbon black-iodine solution mixture, adding the standardized titrant to an accurately weighed portion of the supernatant from the carbon black-iodine mixture until a titration endpoint is reached and determining the concentration of the supernatant by accurately weighing the amount of the standardized titrant necessary to reach the endpoint, wherein the titration endpoint of the supernatant is obtained using an indicating and a reference electrode, and calculating the iodine adsorption number of the carbon black based on the gravimetrically determined concentration of the titrant, the iodine solution, and the supernatant

Determination of uranium in uranyl nitrate solutions of nuclear grade quality - Gravimetric method

International Nuclear Information System (INIS)

1990-01-01

This international Standard specifies a precise and accurate gravimetric method for determining the uranium content in uranyl nitrate product solutions of nuclear grade quality at concentrations above 100 g/l of uranium. Non-volatile impurities influence the accuracy of the method. Uranyl nitrate is converted into uranium octoxide (U 3 O 8 ) by ignition in air to constant mass at 900 deg. C ± 10 deg. C. Calculation of the uranium content in the sample using a gravimetric conversion factor which depends on the isotopic composition of the uranium. The isotopic composition is determined by mass spectrometry

Gravimetric study on the western edge of the Rio de La Plata craton

International Nuclear Information System (INIS)

Rame, G; Miro, R

2010-01-01

This work is about the gravimetric study on the western edge of the Rio de la Plata craton which belongs to the Gondwana fragment in the south of Brazil, Uruguay and central eastern of Argentina. The work consisted of a survey of 332 gravimetric and topographic stations extended from the western edge of the Sierra Chica de Cordoba up to 200 km east on the pampas. The gravity values observed (gobs) were obtained using a LaCoste §Rom berg gravimeter G-961 and 200T Sodin both with 0.01 mGal, referred to IGSN71 (International Gravity Standardization Net 1971) network

Decomposition of Copper (II) Sulfate Pentahydrate: A Sequential Gravimetric Analysis.

Science.gov (United States)

Harris, Arlo D.; Kalbus, Lee H.

1979-01-01

Describes an improved experiment of the thermal dehydration of copper (II) sulfate pentahydrate. The improvements described here are control of the temperature environment and a quantitative study of the decomposition reaction to a thermally stable oxide. Data will suffice to show sequential gravimetric analysis. (Author/SA)

A Comparative Study of the Applied Methods for Estimating Deflection of the Vertical in Terrestrial Geodetic Measurements

Directory of Open Access Journals (Sweden)

Luca Vittuari

2016-04-01

Full Text Available This paper compares three different methods capable of estimating the deflection of the vertical (DoV: one is based on the joint use of high precision spirit leveling and Global Navigation Satellite Systems (GNSS, a second uses astro-geodetic measurements and the third gravimetric geoid models. The working data sets refer to the geodetic International Terrestrial Reference Frame (ITRF co-location sites of Medicina (Northern, Italy and Noto (Sicily, these latter being excellent test beds for our investigations. The measurements were planned and realized to estimate the DoV with a level of precision comparable to the angular accuracy achievable in high precision network measured by modern high-end total stations. The three methods are in excellent agreement, with an operational supremacy of the astro-geodetic method, being faster and more precise than the others. The method that combines leveling and GNSS has slightly larger standard deviations; although well within the 1 arcsec level, which was assumed as threshold. Finally, the geoid model based method, whose 2.5 arcsec standard deviations exceed this threshold, is also statistically consistent with the others and should be used to determine the DoV components where local ad hoc measurements are lacking.

Tectonic evolution of the Paranoá basin: New evidence from gravimetric and stratigraphic data

Science.gov (United States)

Martins-Ferreira, Marco Antonio Caçador; Campos, José Eloi Guimarães; Von Huelsen, Monica Giannoccaro

2018-06-01

Field gravimetric and stratigraphic surveys were conducted with the aim to constraint the mechanisms responsible for the initiation of the Stenian-Tonian Paranoá basin, central Brazil, a subject not yet studied in detail. The Paranoá Group crops out in the external zone of the Brasília Belt, a Neoproterozoic orogen in the western margin of the São Francisco Craton. Detailed geological mapping confirmed the existence of a regional scale fault that controlled sedimentation of the Paranoá Group during the deposition of its basal formations, revealing important details about basin initiation and early evolution. Gravimetric modeling indicates the existence of paleorift structures beneath the Paranoá sequence in the study area. Results from both stratigraphic and gravimetric surveys show strong evidence of mechanical subsidence by faulting during basin initiation. Unsorted, angular, clasts cut by quartz veins and brecciated boulders present in the basal conglomerate, support this hypothesis. Basin initiation faults coincide with deeper paleorift faults and are thus interpreted as reactivations of the older Statherian Araí Rift. The reactivations favored an initial regime of mechanical subsidence, dominated by the development of epirogenic arches subsiding at different rates. Apart from faulting activity, the post-basal sequence presents no evidence of rift environment in the strict sense. Besides, the great lateral continuity and relatively constant thickness of facies, indicate that an initial mechanic subsidence rapidly gave way to flexural subsidence during subsequent stages of basin evolution. The Paranoá Group do not present reliable characteristics that would allow its strict classification as a passive margin. Its main stratigraphic characteristics, tectonic location and basement architecture, indicate that the Paranoá Group was deposited in a cratonic margin basin, and may have been either connected to a passive margin basin at times of sea level rise

Precise and efficient evaluation of gravimetric quantities at arbitrarily scattered points in space

Science.gov (United States)

Ivanov, Kamen G.; Pavlis, Nikolaos K.; Petrushev, Pencho

2017-12-01

Gravimetric quantities are commonly represented in terms of high degree surface or solid spherical harmonics. After EGM2008, such expansions routinely extend to spherical harmonic degree 2190, which makes the computation of gravimetric quantities at a large number of arbitrarily scattered points in space using harmonic synthesis, a very computationally demanding process. We present here the development of an algorithm and its associated software for the efficient and precise evaluation of gravimetric quantities, represented in high degree solid spherical harmonics, at arbitrarily scattered points in the space exterior to the surface of the Earth. The new algorithm is based on representation of the quantities of interest in solid ellipsoidal harmonics and application of the tensor product trigonometric needlets. A FORTRAN implementation of this algorithm has been developed and extensively tested. The capabilities of the code are demonstrated using as examples the disturbing potential T, height anomaly ζ , gravity anomaly Δ g , gravity disturbance δ g , north-south deflection of the vertical ξ , east-west deflection of the vertical η , and the second radial derivative T_{rr} of the disturbing potential. After a pre-computational step that takes between 1 and 2 h per quantity, the current version of the software is capable of computing on a standard PC each of these quantities in the range from the surface of the Earth up to 544 km above that surface at speeds between 20,000 and 40,000 point evaluations per second, depending on the gravimetric quantity being evaluated, while the relative error does not exceed 10^{-6} and the memory (RAM) use is 9.3 GB.

Well known outstanding geoid and relief depressions as regular wave woven features on Eartg (Indian geoid minimum), Moon (SPA basin), Phobos (Stickney crater), and Miranda (an ovoid).

Science.gov (United States)

Kochemasov, Gennady G.

2010-05-01

A very unreliable interpretation of the deepest and large depressions on the Moon and Phobos as the impact features is not synonymous and causes many questions. A real scientific understanding of their origin should take into consideration a fact of their similar tectonic position with that of a comparable depression on so different by size, composition, and density heavenly body as Earth. On Earth as on other celestial bodies there is a fundamental division on two segments - hemispheres produced by an interference of standing warping wave 1 (long 2πR) of four directions [1]. One hemisphere is uplifted (continental, highlands) and the opposite subsided (oceanic, lowlands). Tectonic features made by wave 2 (sectors) adorn this fundamental structure. Thus, on the continental risen segment appear regularly disposed sectors, also uplifted and subsided. On the Earth's eastern continental hemisphere they are grouped around the Pamirs-Hindukush vertex of the structural octahedron made by interfering waves2. Two risen sectors (highly uplifted African and the opposite uplifted Asian) are separated by two fallen sectors (subsided Eurasian and the opposite deeply subsided Indoceanic). The Indoceanic sector with superposed on it subsided Indian tectonic granule (πR/4-structure) produce the deepest geoid minimum of Earth (-112 m). The Moon demonstrates its own geoid minimum of the same relative size and in the similar sectoral tectonic position - the SPA basin [2, 3]. This basin represents a deeply subsided sector of the sectoral structure around the Mare Orientale (one of vertices of the lunar structural octahedron). To this Mare converge four sectors: two subsided - SPA basin and the opposite Procellarum Ocean, and two uplifted - we call them the "Africanda sector" and the opposite "Antiafricanda one" to stress structural similarity with Earth [2]. The highest "Africanda sector" is built with light anorthosites; enrichment with Na makes them even less dense that is required

Time-Resolved Gravimetric Method To Assess Degassing of Roasted Coffee.

Science.gov (United States)

Smrke, Samo; Wellinger, Marco; Suzuki, Tomonori; Balsiger, Franz; Opitz, Sebastian E W; Yeretzian, Chahan

2018-05-30

During the roasting of coffee, thermally driven chemical reactions lead to the formation of gases, of which a large fraction is carbon dioxide (CO 2 ). Part of these gases is released during roasting while part is retained inside the porous structure of the roasted beans and is steadily released during storage or more abruptly during grinding and extraction. The release of CO 2 during the various phases from roasting to consumption is linked to many important properties and characteristics of coffee. It is an indicator for freshness, plays an important role in shelf life and in packaging, impacts the extraction process, is involved in crema formation, and may affect the sensory profile in the cup. Indeed, and in view of the multiple roles it plays, CO 2 is a much underappreciated and little examined molecule in coffee. Here, we introduce an accurate, quantitative, and time-resolved method to measure the release kinetics of gases from whole beans and ground coffee using a gravimetric approach. Samples were placed in a container with a fitted capillary to allow gases to escape. The time-resolved release of gases was measured via the weight loss of the container filled with coffee. Long-term stability was achieved using a customized design of a semimicro balance, including periodic and automatic zero value measurements and calibration procedures. The novel gravimetric methodology was applied to a range of coffee samples: (i) whole Arabica beans and (ii) ground Arabica and Robusta, roasted to different roast degrees and at different speeds (roast air temperatures). Modeling the degassing rates allowed structural and mechanistic interpretation of the degassing process.

Modelling of the Global Geopotential Energy & Stress Field

DEFF Research Database (Denmark)

Schiffer, Christian; Nielsen, S.B.

Lateral density and topography variations yield in and important contribution to the lithospheric stress field. The leading quantity is the Geopotential Energy, the integrated lithostatic pressure in a rock column. The horizontal gradient of this quantity is related to horizontal stresses through...... the Equations of equilibrium of stresses. The Geopotential Energy furthermore can be linearly related to the Geoid under assumption of local isostasy. Satellite Geoid measurements contain, however, also non-isostatic deeper mantle responses of long wavelength. Unfortunately, high-pass filtering of the Geoid...... flow in the presence of local isostasy and a steady state geotherm. Subsequently we use a FEM code to solve the Equations of equilibrium of stresses for a three dimensional elastic shell. The modelled results are shown and compared with the global stress field and other publications....

Modernizing and Upgrading the Astrogeodetic Camera System for Determining Vertical Deflections

Science.gov (United States)

Albayrak, M.; Halicioglu, K.; Basoglu, B.; Ulug, R.; Ozludemir, M. T.; Deniz, R.

2017-12-01

The geoid is the equipotential surface of the Earth. Modeling the geoid with high accuracy is one of the critical issues in Geodesy. Development of geoid modeling is based on geodetic, gravimetric and astrogeodetic techniques. In order to reach the intended accuracy, deflection of the vertical (VD) components, which is obtained by the astrogeodetic techniques, can be used. VD is also very important for providing valuable information on the structure of Earth's gravity field. For this reason, astrogeodetic observations were essential gravity field observables and used for astrogeodetic geoid determinations. Scientists in several countries have developed modern instruments to measure vertical deflections. One of those instruments, namely Astro-geodetic Camera System (ACSYS) was developed in Turkey in 2015. The system components include a telescope, a Charged Coupled Device (CCD), two tiltmeters with the accuracy of 0.01 milliradians, a focuser, a single frequency GPS receiver and a substructure. The first version of the ACSYS is capable of determining astronomical coordinates with an accuracy of 0.2-0.3 arc sec, yet it has some limitations in observation duration. Because of the semi-automated mechanical design, leveling the system towards zenith was a time-consuming process. Since the beginning of 2016, the ACSYS has been modernized through the upgrade of the system with new technological components, hardware and software which is supported by The Scientific and Research Council of Turkey. Upgrade process includes the installation of a high-resolution tiltmeter with an accuracy of 1 nano-radians, implementation of a temperature compensating focuser and fully automatized substructure system. The components of the system are controlled by specially designed and integrated software. In the scope of the modernization studies, the project team has also been working on a unified real-time processing and control software for the ACSYS.v2. This study introduces the

Uncertainty associated with assessing semen volume: are volumetric and gravimetric methods that different?

Science.gov (United States)

Woodward, Bryan; Gossen, Nicole; Meadows, Jessica; Tomlinson, Mathew

2016-12-01

The World Health Organization laboratory manual for the examination of human semen suggests that an indirect measurement of semen volume by weighing (gravimetric method) is more accurate than a direct measure using a serological pipette. A series of experiments were performed to determine the level of discrepancy between the two methods using pipettes and a balance which had been calibrated to a traceable standard. The median weights of 1.0ml and 5.0ml of semen were 1.03 g (range 1.02-1.05 g) and 5.11 g (range 4.95-5.16 g), respectively, suggesting a density for semen between 1.03g and 1.04 g/ml. When the containers were re-weighed after the removal of 5.0 ml semen using a serological pipette, the mean residual loss was 0.12 ml (120 μl) or 0.12 g (median 100 μl, range 70-300 μl). Direct comparison of the volumetric and gravimetric methods in a total of 40 samples showed a mean difference of 0.25ml (median 0.32 ± 0.67ml) representing an error of 8.5%. Residual semen left in the container by weight was on average 0.11 g (median 0.10 g, range 0.05-0.19 g). Assuming a density of 1 g/ml then the average error between volumetric and gravimetric methods was approximately 8% (p gravimetric measurement of semen volume. Laboratories may therefore prefer to provide in-house quality assurance data in order to be satisfied that 'estimating' semen volume is 'fit for purpose' as opposed to assuming a lower uncertainty associated with the WHO recommended method.

Comparison of Metal-on-Metal Hip Simulator Wear Measured by Gravimetric, CMM and Optical Profiling Methods

OpenAIRE

Alberts, Larry Russell; Martinez-Nogues, Vanesa; Cook, Richard; Maul, Christian; Bills, Paul J.; Racasan, Radu; Stolz, Martin; Wood, Robert J. K.

2018-01-01

Simulation of wear in artificial joint implants is critical for evaluating implant designs and materials. Traditional protocols employ the gravimetric method to determine the loss of material by measuring the weight of the implant components before and after various test intervals and after the completed test. However, the gravimetric method cannot identify the location, area coverage or maximum depth of the wear and it has difficulties with proportionally small weight changes in relatively h...

Erosion of water-based cements evaluated by volumetric and gravimetric methods.

Science.gov (United States)

Nomoto, Rie; Uchida, Keiko; Momoi, Yasuko; McCabe, John F

2003-05-01

To compare the erosion of glass ionomer, zinc phosphate and polycarboxylate cements using volumetric and gravimetric methods. For the volumetric method, the eroded depth of cement placed in a cylindrical cavity in PMMA was measured using a dial gauge after immersion in an eroding solution. For the gravimetric method, the weight of the residue of a solution in which a cylindrical specimen had been immersed was measured. 0.02 M lactic acid solution (0.02 M acid) and 0.1 M lactic acid/sodium lactate buffer solution (0.1 M buffer) were used as eroding solutions. The pH of both solutions was 2.74 and the test period was 24 h. Ranking of eroded depth and weight of residue was polycarboxylate>zinc phosphate>glass ionomers. Differences in erosion were more clearly defined by differences in eroded depth than differences in weight of residue. In 0.02 M acid, the erosion of glass ionomer using the volumetric method was effected by the hygroscopic expansion. In 0.1 M buffer, the erosion for polycarboxylate and zinc phosphate using the volumetric method was much greater than that using the gravimetric method. This is explained by cryo-SEM images which show many holes in the surface of specimens after erosion. It appears that zinc oxide is dissolved leaving a spongy matrix which easily collapses under the force applied to the dial gauge during measurement. The volumetric method that employs eroded depth of cement using a 0.1 M buffer solution is able to quantify erosion and to make material comparisons.

Density Imaging of Puy de Dôme Volcano by Joint Inversion of Muographic and Gravimetric Data

Science.gov (United States)

Barnoud, A.; Niess, V.; Le Ménédeu, E.; Cayol, V.; Carloganu, C.

2016-12-01

We aim at jointly inverting high density muographic and gravimetric data to robustly infer the density structure of volcanoes. We use the puy de Dôme volcano in France as a proof of principle since high quality data sets are available for both muography and gravimetry. Gravimetric inversion and muography are independent methods that provide an estimation of density distributions. On the one hand, gravimetry allows to reconstruct 3D density variations by inversion. This process is well known to be ill-posed and intrinsically non unique, thus it requires additional constraints (eg. a priori density model). On the other hand, muography provides a direct measurement of 2D mean densities (radiographic images) from the detection of high energy atmospheric muons crossing the volcanic edifice. 3D density distributions can be computed from several radiographic images, but the number of images is generally limited by field constraints and by the limited number of available telescopes. Thus, muon tomography is also ill-posed in practice.In the case of the puy de Dôme volcano, the density structures inferred from gravimetric data (Portal et al. 2016) and from muographic data (Le Ménédeu et al. 2016) show a qualitative agreement but cannot be compared quantitatively. Because each method has different intrinsic resolutions due to the physics (Jourde et al., 2015), the joint inversion is expected to improve the robustness of the inversion. Such joint inversion has already been applied in a volcanic context (Nishiyama et al., 2013).Volcano muography requires state-of-art, high-resolution and large-scale muon detectors (Ambrosino et al., 2015). Instrumental uncertainties and systematic errors may constitute an important limitation for muography and should not be overlooked. For instance, low-energy muons are detected together with ballistic high-energy muons, decreasing the measured value of the mean density closed to the topography.Here, we jointly invert the gravimetric and

Use of sulfoxides for extraction-gravimetric determination of niobium and tantalum

International Nuclear Information System (INIS)

Nikolaev, A.I.; Babkin, A.G.; Tkachenko, V.G.

1977-01-01

An extraction-gravimetrical technique has been developed for determination of niobium and tantalum. The technique permits simultaneous extraction of tantalum and its concentrating in the aqueous phase; the range of Ta concentrations determined is essentially wider than in case of the routine gravimetric methods. The technique is based upon the fact, that tantalum is extracted by sulfoxides from fluorine-sulphate solutions at lower concentration of Hf and at lower ratios between the volumes of organic and aqueous phases than niobium. Two subsequent extractions by 1M sulfoxide solutions provide for practically complete transfer of tantalum into the organic phase, whereas extraction of niobium is only 3-20%. Sufficient recovery of Ta and Nb from organic phases is provided by re-extraction by NH 4 F solution. The technique is suitable for niobium and tantalum determination at the ratios of their pentoxides from 1:100 to 100:1. The disturbing influence of Fe(3) is suppressed by reductions to Fe(2)

Gravimetric determination of uranium(VI) and thorium(IV) with substituted pyrazolones

International Nuclear Information System (INIS)

Arora, H.C.; Rao, G.N.

1981-01-01

4-Acylpyrazolones like 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP), 1-phenyl-3-methyl-4-p-nitrobenzoyl-5-pyrazolone (PMNP) and 1-phenyl-3-methyl-4-(3,5 dinitrobenzoyl)-5-pyrazolone (PMDP) have been synthesized and developed as gravimetric reagents for the determination of U(VI) and Th(IV). Uranium(VI) is almost quantitatively precipitated with PMBP, PMNP, and PMDP at pH 2.20, 1.85 and 1.70 respectively. The pH values for the complete precipitation of thorium(IV) with PMBP, PMNP and PMDP are 2.90, 2.75 and 2.50 respectively. PMBP has proved to be an efficient ligand for gravimetric determination of U(VI) by direct weighing method after drying at 100 +- 10 deg C. The percentage relative error varies from 0.4 to 1.6 in the determination of U(VI) by this method. The effect of a number of interfering ions on the precipitation of U(VI) by PMBP has been reported. (author)

The use of gravimetric data from GRACE mission in the understanding of polar motion variations

Science.gov (United States)

Seoane, L.; Nastula, J.; Bizouard, C.; Gambis, D.

2009-08-01

Tesseral coefficients C21 and S21 derived from Gravity Recovery and Climate Experiment (GRACE) observations allow to compute the mass term of the polar-motion excitation function. This independent estimation can improve the geophysical models and, in addition, determine the unmodelled phenomena. In this paper, we intend to validate the polar motion excitation derived from GRACE's last release (GRACE Release 4) computed by different institutes: GeoForschungsZentrum (GFZ), Postdam, Germany; Center for Space Research (CSR), Austin, USA; Jet Propulsion Laboratory (JPL), Pasadena, USA, and the Groupe de Recherche en Géodésie Spatiale (GRGS), Toulouse, France. For this purpose, we compare these excitations functions first to the mass term obtained from observed Earth's rotation variations free of the motion term and, second, to the mass term estimated from geophysical fluids models. We confirm the large improvement of the CSR solution, and we show that the GRGS estimate is also well correlated with the geodetic observations. Significant discrepancies exist between the solutions of each centre. The source of these differences is probably related to the data processing strategy. We also consider residuals computed after removing the geophysical models or the gravimetric solutions from the geodetic mass term. We show that the residual excitation based on models is smoother than the gravimetric data, which are still noisy. Still, they are comparable for the χ2 component. It appears that χ2 residual signals using GFZ and JPL data have less variability. Finally, for assessing the impact of the geophysical fluids models choice on our results, we checked two different oceanic excitation series. We show the significant differences in the residuals correlations, especially for the χ1 more sensitive to the oceanic signals.

Aspects of Remote Sensing in the GEOid and Sea level Of the North Atlantic Region (GEOSONAR) Project

DEFF Research Database (Denmark)

Hilger, Klaus Baggesen; Nielsen, Allan Aasbjerg; Knudsen, Per

1999-01-01

The general objectives of the GEOid and Sea level Of the North Atlantic Region (GEOSONAR) project are presented. These include analyses of the dynamics of the ocean and its characteristics. The analyses are mainly based on remote sensing. As an example a data set obtained by the multi-channel Sea-viewing...... Wide Field-of-view Sensor (SeaWiFs) is analysed. The presentation results include the computed principal components (PC) and the maximum autocorrelation factors (MAF). Both methods are expected to be incorporated into future analyses of the state of the ocean....

GOCE Data for Ocean Modelling

DEFF Research Database (Denmark)

Herceg, Matija

and order. The method makes use of all available GOCE gradient data in addition to the global models and aims at improving the determination of Earth’s gravitational field in regional areas. Subsequently, the calculated equipotential surface, known as the geoid, is used together with measurements of sea...... surface height in a calculation of the Mean Dynamic Topography (MDT). This reflects the geostrophic ocean currents and leads to a better understanding of ocean mass and heat transfer. In regional geoid recovery from GOCE gradients, two methods are used, one of them being Least-Squares Collocation (LSC...

Humidity and Gravimetric Equivalency Adjustments for Nephelometer-Based Particulate Matter Measurements of Emissions from Solid Biomass Fuel Use in Cookstoves

Science.gov (United States)

Soneja, Sutyajeet; Chen, Chen; Tielsch, James M.; Katz, Joanne; Zeger, Scott L.; Checkley, William; Curriero, Frank C.; Breysse, Patrick N.

2014-01-01

Great uncertainty exists around indoor biomass burning exposure-disease relationships due to lack of detailed exposure data in large health outcome studies. Passive nephelometers can be used to estimate high particulate matter (PM) concentrations during cooking in low resource environments. Since passive nephelometers do not have a collection filter they are not subject to sampler overload. Nephelometric concentration readings can be biased due to particle growth in high humid environments and differences in compositional and size dependent aerosol characteristics. This paper explores relative humidity (RH) and gravimetric equivalency adjustment approaches to be used for the pDR-1000 used to assess indoor PM concentrations for a cookstove intervention trial in Nepal. Three approaches to humidity adjustment performed equivalently (similar root mean squared error). For gravimetric conversion, the new linear regression equation with log-transformed variables performed better than the traditional linear equation. In addition, gravimetric conversion equations utilizing a spline or quadratic term were examined. We propose a humidity adjustment equation encompassing the entire RH range instead of adjusting for RH above an arbitrary 60% threshold. Furthermore, we propose new integrated RH and gravimetric conversion methods because they have one response variable (gravimetric PM2.5 concentration), do not contain an RH threshold, and is straightforward. PMID:24950062

Humidity and gravimetric equivalency adjustments for nephelometer-based particulate matter measurements of emissions from solid biomass fuel use in cookstoves.

Science.gov (United States)

Soneja, Sutyajeet; Chen, Chen; Tielsch, James M; Katz, Joanne; Zeger, Scott L; Checkley, William; Curriero, Frank C; Breysse, Patrick N

2014-06-19

Great uncertainty exists around indoor biomass burning exposure-disease relationships due to lack of detailed exposure data in large health outcome studies. Passive nephelometers can be used to estimate high particulate matter (PM) concentrations during cooking in low resource environments. Since passive nephelometers do not have a collection filter they are not subject to sampler overload. Nephelometric concentration readings can be biased due to particle growth in high humid environments and differences in compositional and size dependent aerosol characteristics. This paper explores relative humidity (RH) and gravimetric equivalency adjustment approaches to be used for the pDR-1000 used to assess indoor PM concentrations for a cookstove intervention trial in Nepal. Three approaches to humidity adjustment performed equivalently (similar root mean squared error). For gravimetric conversion, the new linear regression equation with log-transformed variables performed better than the traditional linear equation. In addition, gravimetric conversion equations utilizing a spline or quadratic term were examined. We propose a humidity adjustment equation encompassing the entire RH range instead of adjusting for RH above an arbitrary 60% threshold. Furthermore, we propose new integrated RH and gravimetric conversion methods because they have one response variable (gravimetric PM2.5 concentration), do not contain an RH threshold, and is straightforward.

Visual estimation versus gravimetric measurement of postpartum blood loss: a prospective cohort study.

Science.gov (United States)

Al Kadri, Hanan M F; Al Anazi, Bedayah K; Tamim, Hani M

2011-06-01

One of the major problems in international literature is how to measure postpartum blood loss with accuracy. We aimed in this research to assess the accuracy of visual estimation of postpartum blood loss (by each of two main health-care providers) compared with the gravimetric calculation method. We carried out a prospective cohort study at King Abdulaziz Medical City, Riyadh, Saudi Arabia between 1 November 2009 and 31 December 2009. All women who were admitted to labor and delivery suite and delivered vaginally were included in the study. Postpartum blood loss was visually estimated by the attending physician and obstetrics nurse and then objectively calculated by a gravimetric machine. Comparison between the three methods of blood loss calculation was carried out. A total of 150 patients were included in this study. There was a significant difference between the gravimetric calculated blood loss and both health-care providers' estimation with a tendency to underestimate the loss by about 30%. The background and seniority of the assessing health-care provider did not affect the accuracy of the estimation. The corrected incidence of postpartum hemorrhage in Saudi Arabia was found to be 1.47%. Health-care providers tend to underestimate the volume of postpartum blood loss by about 30%. Training and continuous auditing of the diagnosis of postpartum hemorrhage is needed to avoid missing cases and thus preventing associated morbidity and mortality.

Strategy for thermo-gravimetric analysis of K East fuel samples

International Nuclear Information System (INIS)

Lawrence, L.A.

1997-01-01

A strategy was developed for the Thermo-Gravimetric Analysis (TGA) testing of K East fuel samples for oxidation rate determinations. Tests will first establish if there are any differences for dry air oxidation between the K West and K East fuel. These tests will be followed by moist inert gas oxidation rate measurements. The final series of tests will consider pure water vapor i.e., steam

Comparison of neutron scattering, gravimetric and tensiometric methods for measuring soil water content in the field

International Nuclear Information System (INIS)

Jat, R.L.; Das, D.K.; Naskar, G.C.

1975-01-01

Water content of a sandy clay loam soil was measured by neutron scattering, gravimetric and tensiometric methods. Tensiometric measurement based on laboratory moisture retention curve gave comparatively higher moisture content than those obtained by other methods. No significant differences were observed among neutron meter, gravimetric and tensiometric measurement based on field calibration curve. Though for irrigation purposes all the methods can be used equally, use of tensiometric method with field calibration curve is suggested for easy and more accurate soil water content measurement where neutron meter is not available. (author)

Control and Prediction of the Course of Brewery Fermentations by Gravimetric Analysis

Czech Academy of Sciences Publication Activity Database

Košín, P.; Šavel, J.; Brož, A.; Sigler, Karel

2008-01-01

Roč. 53, č. 5 (2008), s. 451-456 ISSN 0015-5632 R&D Projects: GA MŠk 1M0570 Institutional research plan: CEZ:AV0Z50200510 Keywords : brewery fermentation * gravimetric analysis Subject RIV: EE - Microbiology, Virology Impact factor: 1.172, year: 2008

Novel gravimetric measurement technique for quantitative volume calibration in the sub-microliter range

International Nuclear Information System (INIS)

Liang, Dong; Zengerle, Roland; Steinert, Chris; Ernst, Andreas; Koltay, Peter; Bammesberger, Stefan; Tanguy, Laurent

2013-01-01

We present a novel measurement method based on the gravimetric principles adapted from the ASTM E542 and ISO 4787 standards for quantitative volume determination in the sub-microliter range. Such a method is particularly important for the calibration of non-contact micro dispensers as well as other microfluidic devices. The novel method is based on the linear regression analysis of continuously monitored gravimetric results and therefore is referred to as ‘gravimetric regression method (GRM)’. In this context, the regression analysis is necessary to compensate the mass loss due to evaporation that is significant for very small dispensing volumes. A full assessment of the measurement uncertainty of GRM is presented and results in a standard measurement uncertainty around 6 nl for dosage volumes in the range from 40 nl to 1 µl. The GRM has been experimentally benchmarked with a dual-dye ratiometric photometric method (Artel Inc., Westbrook, ME, USA), which can provide traceability of measurement to the International System of Units (SI) through reference standards maintained by NIST. Good precision (max. CV = 2.8%) and consistency (bias around 7 nl in the volume range from 40 to 400 nl) have been observed comparing the two methods. Based on the ASTM and ISO standards on the one hand and the benchmark with the photometric method on the other hand, two different approaches for establishing traceability for the GRM are discussed. (paper)

Comparison of gravimetric, creamatocrit and esterified fatty acid methods for determination of total fat content in human milk.

Science.gov (United States)

Du, Jian; Gay, Melvin C L; Lai, Ching Tat; Trengove, Robert D; Hartmann, Peter E; Geddes, Donna T

2017-02-15

The gravimetric method is considered the gold standard for measuring the fat content of human milk. However, it is labor intensive and requires large volumes of human milk. Other methods, such as creamatocrit and esterified fatty acid assay (EFA), have also been used widely in fat analysis. However, these methods have not been compared concurrently with the gravimetric method. Comparison of the three methods was conducted with human milk of varying fat content. Correlations between these methods were high (r(2)=0.99). Statistical differences (Pmethods. Overall, stronger correlation with lower mean (4.73g/L) and percentage differences (5.16%) was observed with the creamatocrit than the EFA method when compared to the gravimetric method. Furthermore, the ease of operation and real-time analysis make the creamatocrit method preferable. Copyright © 2016. Published by Elsevier Ltd.

Precision gravimetric survey at the conditions of urban agglomerations

Science.gov (United States)

Sokolova, Tatiana; Lygin, Ivan; Fadeev, Alexander

2014-05-01

Large cities growth and aging lead to the irreversible negative changes of underground. The study of these changes at the urban area mainly based on the shallow methods of Geophysics, which extensive usage restricted by technogenic noise. Among others, precision gravimetry is allocated as method with good resistance to the urban noises. The main the objects of urban gravimetric survey are the soil decompaction, leaded to the rocks strength violation and the karst formation. Their gravity effects are too small, therefore investigation requires the modern high-precision equipment and special methods of measurements. The Gravimetry division of Lomonosov Moscow State University examin of modern precision gravimeters Scintrex CG-5 Autograv since 2006. The main performance characteristics of over 20 precision gravimeters were examined in various operational modes. Stationary mode. Long-term gravimetric measurements were carried at a base station. It shows that records obtained differ by high-frequency and mid-frequency (period 5 - 12 hours) components. The high-frequency component, determined as a standard deviation of measurement, characterizes the level of the system sensitivity to external noise and varies for different devices from 2 to 5-7 μGals. Midrange component, which closely meet to the rest of nonlinearity gravimeter drifts, is partially compensated by the equipment. This factor is very important in the case of gravimetric monitoring or observations, when midrange anomalies are the target ones. For the examined gravimeters, amplitudes' deviations, associated with this parameter may reach 10 μGals. Various transportation modes - were performed by walking (softest mode), lift (vertical overload), vehicle (horizontal overloads), boat (vertical plus horizontal overloads) and helicopter. The survey quality was compared by the variance of the measurement results and internal convergence of series. The measurement results variance (from ±2 to ±4 μGals) and its

Study of the corrosion behavior of magnesium alloy weddings in NaCl solutions by gravimetric tests

Energy Technology Data Exchange (ETDEWEB)

Segarra, J. A.; Calderon, B.; Portoles, A.

2015-07-01

In this article, the corrosion behavior of commercial AZ31 welded plates in aqueous chloride media was investigated by means of gravimetric techniques and Neutral Salt Spray tests (NSS). The AZ31 samples tested were welded using Gas Tugsten Arc Welding (GTAW) and different filler materials. Material microstructures were investigated by optical microscopy to stablish the influence of those microstructures in the corrosion behavior. Gravimetric and NSS tests indicate that the use of more noble filler alloys for the sample welding, preventing the reduction of aluminum content in weld beads, does not imply a better corrosion behavior. (Author)

Gravimetric method for in vitro calibration of skin hydration measurements.

Science.gov (United States)

Martinsen, Ørjan G; Grimnes, Sverre; Nilsen, Jon K; Tronstad, Christian; Jang, Wooyoung; Kim, Hongsig; Shin, Kunsoo; Naderi, Majid; Thielmann, Frank

2008-02-01

A novel method for in vitro calibration of skin hydration measurements is presented. The method combines gravimetric and electrical measurements and reveals an exponential dependency of measured electrical susceptance to absolute water content in the epidermal stratum corneum. The results also show that absorption of water into the stratum corneum exhibits three different phases with significant differences in absorption time constant. These phases probably correspond to bound, loosely bound, and bulk water.

Separation and gravimetric determination of rare earths with N-(3-nitrobenzoyl), N-(3-tolyl) hydroxylamine

International Nuclear Information System (INIS)

Agrawal, Y.K.; Kapoor, H.L.

1977-01-01

The N-(3-nitrobenzoyl), N-(3-tolyl) hydroxylamine is used as a reagent for the separation and gravimetric determination of Ce 3+ , La 3+ , Pr 3+ , Nd 3+ , Sm 3+ and Gd 3+ . The optimum conditions of precipitation of these rare earths indicate that, by control of pH and judicious use of masking agents, these ions can be separated from, and determined gravimetrically among several other ions. Further, the stochiometric nature of the N-(3-nitrobenzoyl), N-(3-tolyl) hydroxylamine acid is advantageous for the direct determination by weighting of (C 14 H 11 N 2 O 4 ) 3 M complex without ignition to obtain oxides. These complexes are characterized by infrared spectra

Gravimetric determination of cadmium with o-phenanthroline and iodide

International Nuclear Information System (INIS)

Yoshida, Hitoshi; Mizuno, Kazunori; Taga, Mitsuhiko; Hikime, Seiichiro

1976-01-01

Cadmium forms insoluble mixed ligand complex with o-phenanthroline and iodide ions. By using the complex a new gravimetric method for the determination of cadmium was investigated. The recommended analytical procedure is as follows: Adjust pH value of a solution containing 5 to 45 mg cadmium to 4 with 3 M acetic acid-sodium acetate buffer solution. Add over threefold moles of potassium iodide to the solution and heat to just before boiling. To the solution add 0.1% ascorbic acid solution and then 0.1 M o-phenanthroline solution drop by drop in excess with stirring, and cool the mixture to room temperature. Filter the precipitates and wash first with 0.01% potassium iodide solution and then with water. Dry the precipitates at 110 0 C for two hours and weigh as Cd(o-phen) 2 I 2 (I). The gravimetric factor of the complex for cadmium is 0.1547. Chemical composition of the precipitate is variable when o-phenanthroline is added less than twofold moles to cadmium. Adding the o-phenanthroline solution 2.4-fold moles against cadmium, the ternary complex (I) precipitates quantitatively. Though a large excess of iodide ion in the solution contaminated the precipitate, the contamination was avoided when precipitation was carryed out at high temperature and in the presence of ascorbic acid. By the presented procedure 5 to 45 mg of cadmium are determined with a standard deviation of 0 C. (JPN)

Computation of improved tidal parameters at the gravimetric station of Brasimone

Directory of Open Access Journals (Sweden)

P. Baldi

1997-06-01

Full Text Available Since 1991 a GWR superconducting gravimeter has been working in a laboratory at the Brasimone ENEA Research Centre, near Bologna (Italy, in the frame of an experimental program to verify Newton's law over distances of the order of 10-100 m. Owing to the aim of the experiment, the gravimeter was moved to different laboratories in the same area, but from August 1995 to date it has been working continuously in the same laboratory in the frame of the preliminary program of the Global Geodynamics Project. The site, belonging to a building of a dismissed nuclear power plant, is free from noise due to human activities, and is thus highly suitable for recording Earth tides. Starting from a set of gravimetric and atmospheric pressure data of high quality relative to 22 months of observation, we performed the tidal analysis using Eterna 3.2 software in order to compute amplitudes, gravimetric factors and phases of the main waves of the Tamura 1987 catalogue. The accuracy of the method adopted for the calibration of the gravimeter, the values of the principal waves and the result of the computation of atmospheric pressure admittance are described.

Mycotoxin metrology: Gravimetric production of zearalenone calibration solution

Science.gov (United States)

Rego, E. C. P.; Simon, M. E.; Li, Xiuqin; Li, Xiaomin; Daireaux, A.; Choteau, T.; Westwood, S.; Josephs, R. D.; Wielgosz, R. I.; Cunha, V. S.

2018-03-01

Food safety is a major concern for countries developing metrology and quality assurance systems, including the contamination of food and feed by mycotoxins. To improve the mycotoxin analysis and ensure the metrological traceability, CRM of calibration solution should be used. The production of certified mycotoxin solutions is a major challenge due to the limited amount of standard for conducting a proper purity study and due to the cost of standards. The CBKT project was started at BIPM and Inmetro produced gravimetrically one batch of zearelenone in acetronitrile (14.708 ± 0.016 μg/g, k=2) and conducted homogeneity, stability and value assignment studies.

A highly accurate absolute gravimetric network for Albania, Kosovo and Montenegro

Science.gov (United States)

Ullrich, Christian; Ruess, Diethard; Butta, Hubert; Qirko, Kristaq; Pavicevic, Bozidar; Murat, Meha

2016-04-01

The objective of this project is to establish a basic gravity network in Albania, Kosovo and Montenegro to enable further investigations in geodetic and geophysical issues. Therefore the first time in history absolute gravity measurements were performed in these countries. The Norwegian mapping authority Kartverket is assisting the national mapping authorities in Kosovo (KCA) (Kosovo Cadastral Agency - Agjencia Kadastrale e Kosovës), Albania (ASIG) (Autoriteti Shtetëror i Informacionit Gjeohapësinor) and in Montenegro (REA) (Real Estate Administration of Montenegro - Uprava za nekretnine Crne Gore) in improving the geodetic frameworks. The gravity measurements are funded by Kartverket. The absolute gravimetric measurements were performed from BEV (Federal Office of Metrology and Surveying) with the absolute gravimeter FG5-242. As a national metrology institute (NMI) the Metrology Service of the BEV maintains the national standards for the realisation of the legal units of measurement and ensures their international equivalence and recognition. Laser and clock of the absolute gravimeter were calibrated before and after the measurements. The absolute gravimetric survey was carried out from September to October 2015. Finally all 8 scheduled stations were successfully measured: there are three stations located in Montenegro, two stations in Kosovo and three stations in Albania. The stations are distributed over the countries to establish a gravity network for each country. The vertical gradients were measured at all 8 stations with the relative gravimeter Scintrex CG5. The high class quality of some absolute gravity stations can be used for gravity monitoring activities in future. The measurement uncertainties of the absolute gravity measurements range around 2.5 micro Gal at all stations (1 microgal = 10-8 m/s2). In Montenegro the large gravity difference of 200 MilliGal between station Zabljak and Podgorica can be even used for calibration of relative gravimeters

Evaluation of the gravimetric tetraphenylarsonium method for the determination of Tc(VII)

International Nuclear Information System (INIS)

Pacer, R.A.

1980-01-01

Solubility losses in the gravimetric tetraphenylarsonium method for determining pertechnetate have been evaluated. Liquid scintillation counting was used to measure the β - activity of 99 Tc in the filtrate, and indicated solubility losses of about 1% in analyses yielding 40 to 50 mg of precipitate. The solubility product of (C 6 H 5 ) 4 AsTcO 4 is estimated to be (8.6 +- 0.2) x 10 -10 at room temperature (24 to 25 0 ), and Ksub(sp) for (C 6 H 5 ) 4 AsReO 4 at approximately 21 to 23 0 is estimated at (2.6 +- 0.3) x 10 -9 . Both values are satisfactory for gravimetric purposes, but to keep solubility losses within 1% at least 40 mg of (C 6 H 5 ) 4 AsTcO 4 or 80 mg of (C 6 H 5 ) 4 AsReO 4 should be obtained (assuming 20 ml of solution, 20 to 30% excess of precipitant, and 6 or 7 washes with 5-ml portions of distilled water). (author)

Venus spherical harmonic gravity model to degree and order 60

Science.gov (United States)

Konopliv, Alex S.; Sjogren, William L.

1994-01-01

The Magellan and Pioneer Venus Orbiter radiometric tracking data sets have been combined to produce a 60th degree and order spherical harmonic gravity field. The Magellan data include the high-precision X-band gravity tracking from September 1992 to May 1993 and post-aerobraking data up to January 5, 1994. Gravity models are presented from the application of Kaula's power rule for Venus and an alternative a priori method using surface accelerations. Results are given as vertical gravity acceleration at the reference surface, geoid, vertical Bouguer, and vertical isostatic maps with errors for the vertical gravity and geoid maps included. Correlation of the gravity with topography for the different models is also discussed.

Magnetometric and gravimetric surveys in fault detection over Acambay System

Science.gov (United States)

García-Serrano, A.; Sanchez-Gonzalez, J.; Cifuentes-Nava, G.

2013-05-01

In commemoration of the centennial of the Acambay intraplate earthquake of November 19th 1912, we carry out gravimetric and magnetometric surveys to define the structure of faults caused by this event. The study area is located approximately 11 km south of Acambay, in the Acambay-Tixmadeje fault system, where we performed two magnetometric surveys, the first consisting of 17 lines with a spacing of 35m between lines and 5m between stations, and the second with a total of 12 lines with the same spacing, both NW. In addition to these two lines we performed gravimetric profiles located in the central part of each magnetometric survey, with a spacing of 25m between stations, in order to correlate the results of both techniques, the lengths of such profiles were of 600m and 550m respectively. This work describes the data processing including directional derivatives, analytical signal and inversion, by means of which we obtain results of magnetic variations and anomaly traits highly correlated with those faults. It is of great importance to characterize these faults given the large population growth in the area and settlement houses on them, which involves a high risk in the security of the population, considering that these are active faults and cannot be discard earthquakes associated with them, so it is necessary for the authorities and people have relevant information to these problem.

Geopotential coefficient determination and the gravimetric boundary value problem: A new approach

Science.gov (United States)

Sjoeberg, Lars E.

1989-01-01

New integral formulas to determine geopotential coefficients from terrestrial gravity and satellite altimetry data are given. The formulas are based on the integration of data over the non-spherical surface of the Earth. The effect of the topography to low degrees and orders of coefficients is estimated numerically. Formulas for the solution of the gravimetric boundary value problem are derived.

Moving to a Modernized Height Reference System in Canada: Rationale, Status and Plans

Science.gov (United States)

Veronneau, M.; Huang, J.

2007-05-01

A modern society depends on a common coordinate reference system through which geospatial information can be interrelated and exploited reliably. For height measurements this requires the ability to measure mean sea level elevations easily, accurately, and at the lowest possible cost. The current national reference system for elevations, the Canadian Geodetic Vertical Datum of 1928 (CGVD28), offers only partial geographic coverage of the Canadian territory and is affected by inaccuracies that are becoming more apparent as users move to space- based technologies such as GPS. Furthermore, the maintenance and expansion of the national vertical network using spirit-levelling, a costly, time consuming and labour intensive proposition, has only been minimally funded over the past decade. It is now generally accepted that the most sustainable alternative for the realization of a national vertical datum is a gravimetric geoid model. This approach defines the datum in relation to an ellipsoid, making it compatible with space-based technologies for positioning. While simplifying access to heights above mean sea level all across the Canadian territory, this approach imposes additional demands on the quality of the geoid model. These are being met by recent and upcoming space gravimetry missions that have and will be measuring the Earth`s gravity field with increasing and unprecedented accuracy. To maintain compatibility with the CGVD28 datum materialized at benchmarks, the current first-order levelling can be readjusted by constraining geoid heights at selected stations of the Canadian Base Network. The new reference would change CGVD28 heights of benchmarks by up to 1 m across Canada. However, local height differences between benchmarks would maintain a relative precision of a few cm or better. CGVD28 will co-exist with the new height reference as long as it will be required, but it will undoubtedly disappear as benchmarks are destroyed over time. The adoption of GNSS

Gravimetric and volumetric approaches adapted for hydrogen sorption measurements with in situ conditioning on small sorbent samples

International Nuclear Information System (INIS)

Poirier, E.; Chahine, R.; Tessier, A.; Bose, T.K.

2005-01-01

We present high sensitivity (0 to 1 bar, 295 K) gravimetric and volumetric hydrogen sorption measurement systems adapted for in situ sample conditioning at high temperature and high vacuum. These systems are designed especially for experiments on sorbents available in small masses (mg) and requiring thorough degassing prior to sorption measurements. Uncertainty analysis from instrumental specifications and hydrogen absorption measurements on palladium are presented. The gravimetric and volumetric systems yield cross-checkable results within about 0.05 wt % on samples weighing from (3 to 25) mg. Hydrogen storage capacities of single-walled carbon nanotubes measured at 1 bar and 295 K with both systems are presented

Determination of plutonium in pure plutonium nitrate solutions - Gravimetric method

International Nuclear Information System (INIS)

1987-01-01

This International Standard specifies a precise and accurate gravimetric method for determining the concentration of plutonium in pure plutonium nitrate solutions and reference solutions, containing between 100 and 300 g of plutonium per litre, in a nitric acid medium. The weighed portion of the plutonium nitrate is treated with sulfuric acid and evaporated to dryness. The plutonium sulfate is decomposed and formed to oxide by heating in air. The oxide is ignited in air at 1200 to 1250 deg. C and weighed as stoichiometric plutonium dioxide, which is stable and non-hygroscopic

Gravimetric survey and modeling of the basement morphology in the sedimentary thickness characterization, NE portion of Paraná Sedimentary Basin - Brazil

Directory of Open Access Journals (Sweden)

Maximilian Fries

2017-05-01

Full Text Available ABSTRACT: The northeast portion of the Paraná Sedimentary Basin is distinguished by structural highs as the known Pitanga Dome, an uplifted structure identified in the last century. It represents a geological and evolutionary evidence of the Paraná Sedimentary Basin and has undergone inspired studies and intense exploration surveys. This study consists of a gravimetric survey in the Pitanga Dome area, State of São Paulo, Brazil. The Bouguer gravity anomalies have been identified and related to the structural high, sedimentary thickness, and the basement morphology. Processing and enhancement techniques were used for forward modeling based on previous studies. The three models from profiles sectioning the dome have a sedimentary thickness varying from 200 to 1.250 meters. The adopted methodology has provided important results determining that the Pitanga Dome can be understood through rational 3D visualization. The area can be interpreted as an undulating basement with thinning of sedimentary rocks related to deep features (structures in the crust/mantle limit (Moho uplift. This characteristic is confirmed by the sedimentary layer thickening present throughout the surrounding area. The results also offer important insights and support for further studies concerning the genesis and evolution of this and other uplifted structures of the Paraná Sedimentary Basin.

Study of the corrosion behavior of magnesium alloy weldings in NaCl solutions by gravimetric tests

Directory of Open Access Journals (Sweden)

Segarra, José A.

2015-09-01

Full Text Available In this article, the corrosion behavior of commercial AZ31 welded plates in aqueous chloride media was investigated by means of gravimetric techniques and Neutral Salt Spray tests (NSS. The AZ31 samples tested were welded using Gas Tugsten Arc Welding (GTAW and different filler materials. Material microstructures were investigated by optical microscopy to stablish the influence of those microstructures in the corrosion behavior. Gravimetric and NSS tests indicate that the use of more noble filler alloys for the sample welding, preventing the reduction of aluminum content in weld beads, does not imply a better corrosion behavior.En este artículo se ha investigado el comportamiento frente a la corrosión en medios acuosos salinos de chapas soldadas de aleación AZ31 mediante técnicas gravimétricas y ensayo en cámara de niebla salina. Las muestras estudiadas han sido soldadas mediante soldadura TIG (Tungsten Inert Gas y con diferentes materiales de aporte. En el estudio se ha empleado microscopía óptica para analizar la microestructura. Los ensayos de gravimetría y los ensayos de niebla salina indican que el empleo de materiales de aporte más nobles para soldar las muestras evitando la disminución del contenido en aluminio en los cordones, no implica un mejor comportamiento frente a la corrosión.

Modified method for zirconium or hafnium gravimetric determination with glycolic acid derivatives

International Nuclear Information System (INIS)

Barbieri, R.S.; Rocha, J.C.; Terra, V.R.; Marques Neto, A.

1989-01-01

The conditions for gravimetric determination of zirconium or hafnium by glicolic acid derivatives were studied by thermogravimetric analysis. The method utilized shown that after precipitation, washing and drying of precipitates at 150 0 C, the resulting solid was weighed in the form of [M{RCH(OH)COO} 4 ] (M = Zr,Hf;R = C 6 H 5 , β-C 10 H 7 ,p-BrC 6 H 4 ). (author) [pt

Comparison Of Metal Corrosion Inhibition By Gravimetric And Linear Polarization Resistance Methods

OpenAIRE

Banerji, Shankha

1992-01-01

Studies were conducted to evaluate the effectiveness of various dosages of the selected silicate and phosphate compounds applied for corrosion inhibition of cast iron, copper, lead, and galvanized steel specimens. The compounds selected for study were zinc polyphosphate (Calgon C-39), zinc orthophosphate (Virchem V-931), sodium metasilicate and glassy silicate. The effectiveness of these compounds for corrosion inhibition were studied under differing water quality conditions using gravimetric...

Photometrically measured continuous personal PM(2.5) exposure: levels and correlation to a gravimetric method.

Science.gov (United States)

Lanki, Timo; Alm, Sari; Ruuskanen, Juhani; Janssen, Nicole A H; Jantunen, Matti; Pekkanen, Juha

2002-05-01

There is evidence that hourly variations in exposure to airborne particulate matter (PM) may be associated with adverse health effects. Still there are only few published data on short-term levels of personal exposure to PM in community settings. The objectives of the study were to assess hourly and shorter-term variations in personal PM(2.5) exposure in Helsinki, Finland, and to compare results from portable photometers to simultaneously measured gravimetric concentrations. The effect of relative humidity on the photometric results was also evaluated. Personal PM(2.5) exposures of elderly persons were assessed for 24 h every second week, resulting in 308 successful measurements from 47 different subjects. Large changes in concentrations in minutes after cooking or changing microenvironment were seen. The median of daily 1-h maxima was over twice the median of 24-h averages. There was a strong significant association between the two means, which was not linear. Median (95th percentile) of the photometric 24-h concentrations was 12.1 (37.7) and of the 24-h gravimetric concentrations 9.2 (21.3) microg/m3. The correlation between the photometric and the gravimetric method was quite good (R2=0.86). Participants spent 94.1% of their time indoors or in a vehicle, where relative humidity is usually low and thus not likely to cause significant effects on photometric results. Even outdoors, the relative humidity had only modest effect on concentrations. Photometers are a promising method to explore the health effects of short-term variation in personal PM(2.5) exposure.

A new and simple gravimetric method for determination of uranium

International Nuclear Information System (INIS)

Saxena, A.K.

1994-01-01

A new and simple gravimetric method for determining uranium has been described. Using a known quantity of uranyl nitrate as the test solution, an alcoholic solution of 2-amino-2-methyl 1:3 propanediol (AMP) was added slowly. A yellow precipitate was obtained which was filtered through ashless filter paper, washed with alcohol, dried and ignited at 800 degC for 4h. It gave a black powder as a product which was shown by X-ray diffraction to be U 3 O 8 . The percentage error was found in the range -0.09 to +0.89. (author). 8 refs., 1 tab

Gravimetric determination of hafnium through its arsenate in carbide and boride of hafnium

International Nuclear Information System (INIS)

Rasulbekova, R.A.; Mamedov, I.A.

1976-01-01

A gravimetric method of determining hafnium through hydroarsenate has been recommended. The method differs from the known ones by its simplicity and by the recalculation coefficient which is more than by 50% smaller than that used in preparing a weight form of HfO 2 . Upon development of gravimetric determination of hafnium through hydro-and pyroarsenate, an investigation has been conducted with the aim to find some physico-chemical constants of hafnium hydroarsenate. The weighed amount of hafnium hydroarsenate is dissolved in sulphuric acid (2:5). The precipitate of hafnium hydroarsenate has been studied for recording infrared absorption spectra. Thermographic analysis of the precipitate has been performed. Thermogram reveals endothermal effect at 105 deg C and exothermal at 840 deg C. Water solubility of hafnium has been determined equal to 1.75x10 6 g mol/l. The corresponding solubility product of the precipitate has been calculated which is 2.1x10 -17 . It is shown that the method possesses certain selectivity, sufficient accuracy, and is rather fast. It has been established that determination can be performed in the presence of excess amounts of ions

A cost-effective technique for integrating personal radiation dose assessment with personal gravimetric sampling

International Nuclear Information System (INIS)

Strydom, R.; Rolle, R.; Van der Linde, A.

1992-01-01

During recent years there has been an increasing awareness internationally of radiation levels in the mining and milling of radioactive ores, including those from non-uranium mines. A major aspect of radiation control is concerned with the measurement of radiation levels and the assessment of radiation doses incurred by individual workers. Current techniques available internationally for personnel monitoring of radiation exposures are expensive and there is a particular need to reduce the cost of personal radiation monitoring in South African gold mines because of the large labour force employed. In this regard the obvious benefits of integrating personal radiation monitoring with existing personal monitoring systems already in place in South African gold mines should be exploited. A system which can be utilized for this purpose is personal gravimetric sampling. A new cost-effective technique for personal radiation monitoring, which can be fully integrated with the personal gravimetric sampling strategy being implemented on mines, has been developed in South Africa. The basic principles of this technique and its potential in South African mines are described. 9 refs., 7 figs

Near infrared spectrometry for faecal fat measurement: comparison with conventional gravimetric and titrimetric methods.

Science.gov (United States)

Benini, L; Caliari, S; Guidi, G C; Vaona, B; Talamini, G; Vantini, I; Scuro, L A

1989-01-01

This investigation was aimed at comparing a new method for measuring faecal fat excretion, carried out with a semi-automated instrument by using near infrared analysis (NIRA), with the traditional titrimetric (Van de Kamer) and gravimetric (Sobel) methods. Near infrared analysis faecal fat was assayed on the three day stool collection from 118 patients (68 chronic pancreatitis, 19 organic diseases of the gastrointestinal tract, 19 alcoholic liver disease, 12 functional gastrointestinal disorders). A strict linear correlation was found between NIRA and both the titrimetric (r = 0.928, p less than 0.0001) and the gravimetric (r = 0.971, p less than 0.0001) methods. On homogenised faeces, a mean coefficient of variation of 2.1 (SD 1.71)% was found. Before homogenisation (where a mean coefficient of variation of 7% was found) accurate results were obtained when the mean of five measurements was considered. In conclusion, the assay of faecal fat excretion by the near infrared reflessometry appears a simple, rapid and reliable method for measuring steatorrhoea. PMID:2583563

Determination of uranium in coated fuel particle compact by potassium fluoride fusion-gravimetric method

International Nuclear Information System (INIS)

Ito, Mitsuo; Iso, Shuichi; Hoshino, Akira; Suzuki, Shuichi.

1992-03-01

Potassium fluoride-gravimetric method has been developed for the determination of uranium in TRISO type-coated fuel particle compact. Graphite matrix in the fuel compact is burned off by heating it in a platinum crucible at 850degC. The coated fuel particles thus obtained are decomposed by fusion with potassium fluoride at 900degC. The melt was dissolved with sulfuric acid. Uranium is precipitated as ammonium diuranate, by passing ammonia gas through the solution. The resulting precipitate is heated in a muffle furnace at 850degC, to convert uranium into triuranium octoxide. Uranium in the triuranium octoxide was determined gravimetrically. Ten grams of caoted fuel particles were completely decomposed by fusion with 50 g of potassium fluoride at 900degC for 3 hrs. Analytical result for uranium in the fuel compact by the proposed method was 21.04 ± 0.05 g (n = 3), and was in good agreement with that obtained by non-destructive γ-ray measurement method : 21.01 ± 0.07 g (n = 3). (author)

The Comparison Of Silicon Analysis For The Uranium Silicide Fuel Using Spectrophotometrical And Gravimetrical Methods

International Nuclear Information System (INIS)

Putro, P. K.; Suripto, A.; Putra, S.; Gunanjar

1996-01-01

The analysis of silicon content in the uranium silicide fuel spectro-photometrical and gravimetrical method have been performed. The nitrous oxide-acetylene was used in the atomic absorption spectrophotometry (AAS) on the wave length of 251.6 nm, and the mixture of ammonium hepta molybdate complexes and SnC1 2 as reductor were applied during analysis by UV-VIS spectrophotometry (UV-VIS) on the wave length of 757.5 mm. The reagent of HCLO 4 and HNO 3 were used for determining Si content by gravimetrical methods. The results of this comparison is as follows: the accuracy result is around 96.37 % + 0.24 % for the Si concentration up to 300 ppm (the AAS), is 138.60 % = 0.43 % for the Si concentration range between 0.1-1.5 ppm (UV-VIS), and is 51.13 % + 0.8 % for 1 gram of Si (gravimetry). The results also show that the lowest analytical error is obtained by AAS method

A problem in gravimetric method for the determination of rare earth elements as oxide after the fluoride separation

International Nuclear Information System (INIS)

Takada, Kunio

1979-01-01

For the gravimetric determination of lanthanum, it was precipitated as fluoride and converted to oxide by igniting (ca. 930 0 C) in a town gas flame. However, the oxidation of lanthanum fluoride by ignition was incomplete, the major part of the precipitate being converted to oxyfluoride (LaOF) and a mixture of oxide and oxyfluoride resulted. Therefore, analytical results were generally (5 -- 7)% higher than theoretically expected. The lanthanum fluoride became converted into the oxide by repeating ignition (ca. 1070 0 C) three times, each for (30 -- 40)min. However, the weight was lower than that of the corresponding sesquioxide, La 2 O 3 . Except for ytterbium and lutetium, gravimetric results as oxides for the other rare earth elements (Y, Pr, Nd, Sm, Eu and Gd) were higher than theoretical values. Therefore, the precipitation of the rare earth elements as fluoride and the subsequent determination as oxide by ignition of the fluoride could not be recommended as the gravimetric method for the rare earths. In order to obtain accurate results for major to minor amounts of the rare earth elements, an EDTA titration at pH 6 should be used after the dissolution of fluoride in acid, if the fluoride precipitation separation is involved. (author)

The use of cerium(IV) phosphate for the gravimetric determination and separation of cerium

International Nuclear Information System (INIS)

Masin, V.; Dolezal, J.

1978-01-01

A method for the gravimetric determination of cerium as Ce 3 (PO 4 ) 4 is described. Cerium can be separated from many metals in this form, as well as from permanganate and dichromate; the cerium separated can then be titrated with iron(II) solution. The method was verified for the determination of cerium in a rare earth concentrate. (Auth.)

Design and realization of the high-precision weighing systems as the gravimetric references in PTB's national water flow standard

International Nuclear Information System (INIS)

Engel, Rainer; Beyer, Karlheinz; Baade, Hans-Joachim

2012-01-01

PTB's ‘Hydrodynamic Test Field’, which represents a high-accuracy water flow calibration facility, serves as the national primary standard for liquid flow measurands. As the core reference device of this flow facility, a gravimetric standard has been incorporated, which comprises three special-design weighing systems: 300 kg, 3 tons and 30 tons. These gravimetric references were realized as a combination of a strain-gauge-based and an electromagnetic-force-compensation load-cell-based balance, each. Special emphasis had to be placed upon the dynamics design of the whole weighing system, due to the high measurement resolution and the dynamic behavior of the weighing systems, which are dynamically affected by mechanical vibrations caused by environmental impacts, flow machinery operation, flow noise in the pipework and induced wave motions in the weigh tanks. Taking into account all the above boundary conditions, the design work for the gravimetric reference resulted in a concrete foundation ‘rock’ of some 300 tons that rests on a number of vibration isolators. In addition to these passively operating vibration isolators, the vibration damping effect is enhanced by applying an electronic level regulation device. (paper)

GRACE gravity model: assssment in terms of deep ocean currents from hydrography and from the ECCO ocean model

Science.gov (United States)

Zlotnicki, V.; Stammer, D.; Fukumori, I.

2003-01-01

Here we assess the new generation of gravity models, derived from GRACE data. The differences between a global geoid model (one from GRACE data and one the well-known EGM-96), minus a Mean Sea Surface derived from over a decade of altimetric data are compared to hydrographic data from the Levitus compilation and to the ECCO numerical ocean model, which assimilates altimetry and other data.

Providing long-term trend and gravimetric factor at Chandler period from superconducting gravimeter records by using Singular Spectrum Analysis along with its multivariate extension

Science.gov (United States)

Gruszczynska, M.; Rosat, S.; Klos, A.; Bogusz, J.

2017-12-01

In this study, Singular Spectrum Analysis (SSA) along with its multivariate extension MSSA (Multichannel SSA) were used to estimate long-term trend and gravimetric factor at the Chandler wobble frequency from superconducting gravimeter (SG) records. We have used data from seven stations located worldwide and contributing to the International Geodynamics and Earth Tides Service (IGETS). The timespan ranged from 15 to 19 years. Before applying SSA and MSSA, we had removed local tides, atmospheric (ECMWF data), hydrological (MERRA2 products) loadings and non-tidal ocean loading (ECCO2 products) effects. In the first part of analysis, we used the SSA approach in order to estimate the long-term trends from SG observations. We use the technique based on the classical Karhunen-Loève spectral decomposition of time series into long-term trend, oscillations and noise. In the second part, we present the determination of common time-varying pole tide (annual and Chandler wobble) to estimate gravimetric factor from SG time series using the MSSA approach. The presented method takes advantage over traditional methods like Least Squares Estimation by determining common modes of variability which reflect common geophysical field. We adopted a 6-year lag-window as the optimal length to extract common seasonal signals and the Chandler components of the Earth polar motion. The signals characterized by annual and Chandler wobble account for approximately 62% of the total variance of residual SG data. Then, we estimated the amplitude factors and phase lags of Chandler wobble with respect to the IERS (International Earth Rotation and Reference Systems Service) polar motion observations. The resulting gravimetric factors at the Chandler Wobble period are finally compared with previously estimates. A robust estimate of the gravimetric Earth response to the Chandlerian component of the polar motion is required to better constrain the mantle anelasticity at this frequency and hence the

Determination of uranium by a gravimetric-volumetric titration method

International Nuclear Information System (INIS)

Krtil, J.

1998-01-01

A volumetric-gravimetric modification of a method for the determination of uranium based on the reduction of uranium to U (IV) in a phosphoric acid medium and titration with a standard potassium dichromate solution is described. More than 99% of the stoichiometric amount of the titrating solution is weighed and the remainder is added volumetrically by using the Mettler DL 40 RC Memotitrator. Computer interconnected with analytical balances collects continually the data on the analyzed samples and evaluates the results of determination. The method allows to determine uranium in samples of uranium metal, alloys, oxides, and ammonium diuranate by using aliquot portions containing 30 - 100 mg of uranium with the error of determination, expressed as the relative standard deviation, of 0.02 - 0.05%. (author)

Nuclear fuel technology - Determination of uranium in uranyl nitrate solutions of nuclear grade quality - Gravimetric method

International Nuclear Information System (INIS)

2003-01-01

This International Standard specifies a precise and accurate gravimetric method for determining the mass fraction of uranium in uranyl nitrate solutions of nuclear grade quality containing more than 100 g/kg of uranium. Non-volatile impurities influence the accuracy of the method

Comparison of gravimetric and spectrophotometric methods for the determination of O/U ratios in uranium oxides

International Nuclear Information System (INIS)

Esteban, Adolfo; Eppis, Maria Rosa

2004-01-01

One important parameter to specify in nuclear fuels is the oxygen-metal ratio; many tests were described in literature to determine it. Possibly, gravimetric methods are the most used and usually a good precision was obtained analysing sintered materials. However, the humidity sorbed in the samples and impurities affect these methods, especially in powders. On the other hand, the spectrophotometric methods determine oxygen-uranium ratio by measuring the absorbances of different ionic species in phosphoric acid. This technique is simply and is not affected by humidity and impurities. Owing to discrepancy in the results between both methods, it was carried out in our laboratory, a study on various gravimetric and spectrophotometric methods. Several assays and analysis were performed comparing test procedures, trying to obtain better precision and accuracy. This work presents the results obtained and the recommend procedure to use with sintered and unsintered materials

Gravimetric Analysis of Bismuth in Bismuth Subsalicylate Tablets: A Versatile Quantitative Experiment for Undergraduate Laboratories

Science.gov (United States)

Davis, Eric; Cheung, Ken; Pauls, Steve; Dick, Jonathan; Roth, Elijah; Zalewski, Nicole; Veldhuizen, Christopher; Coeler, Joel

2015-01-01

In this laboratory experiment, lower- and upper-division students dissolved bismuth subsalicylate tablets in acid and precipitated the resultant Bi[superscript 3+] in solution with sodium phosphate for a gravimetric determination of bismuth subsalicylate in the tablets. With a labeled concentration of 262 mg/tablet, the combined data from three…

Gravity model development for precise orbit computations for satellite altimetry

Science.gov (United States)

Marsh, James G.; Lerch, Francis, J.; Smith, David E.; Klosko, Steven M.; Pavlis, Erricos

1986-01-01

Two preliminary gravity models developed as a first step in reaching the TOPEX/Poseidon modeling goals are discussed. They were obtained by NASA-Goddard from an analysis of exclusively satellite tracking observations. With the new Preliminary Gravity Solution-T2 model, an improved global estimate of the field is achieved with an improved description of the geoid.

GOCE in ocean modelling - Point mass method applied on GOCE gravity gradients

DEFF Research Database (Denmark)

Herceg, Matija; Knudsen, Per

This presentation is an introduction to my Ph.D project. The main objective of the study is to improve the methodology for combining GOCE gravity field models with satellite altimetry to derive optimal dynamic ocean topography models for oceanography. Here a method for geoid determination using...

Synergistic improvement of gas sensing performance by micro-gravimetrically extracted kinetic/thermodynamic parameters

International Nuclear Information System (INIS)

Guo, Shuanbao; Xu, Pengcheng; Yu, Haitao; Cheng, Zhenxing; Li, Xinxin

2015-01-01

Highlights: • Sensing material can be comprehensively optimized by using gravimetric cantilever. • Kinetic-thermodynamic model parameters are quantitatively extracted by experiment • Sensing-material performance is synergistically optimized by extracted parameters. - Abstract: A novel method is explored for comprehensive design/optimization of organophosphorus sensing material, which is loaded on mass-type microcantilever sensor. Conventionally, by directly observing the gas sensing response, it is difficult to build quantitative relationship with the intrinsic structure of the material. To break through this difficulty, resonant cantilever is employed as gravimetric tool to implement molecule adsorption experiment. Based on the sensing data, key kinetic/thermodynamic parameters of the material to the molecule, including adsorption heat −ΔH°, adsorption/desorption rate constants K a and K d , active-site number per unit mass N′ and surface coverage θ, can be quantitatively extracted according to physical–chemistry theories. With gaseous DMMP (simulant of organophosphorus agents) as sensing target, the optimization route for three sensing materials is successfully demonstrated. Firstly, a hyper-branched polymer is evaluated. Though suffering low sensitivity due to insufficient N′, the bis(4-hydroxyphenyl)-hexafluoropropane (BHPF) sensing-group exhibits satisfactory reproducibility due to appropriate −ΔH°. To achieve more sensing-sites, KIT-5 mesoporous-silica with higher surface-area is assessed, resulting in good sensitivity but too high −ΔH° that brings poor repeatability. After comprehensive consideration, the confirmed BHPF sensing-group is grafted on the KIT-5 carrier to form an optimized DMMP sensing nanomaterial. Experimental results indicate that, featuring appropriate kinetic/thermodynamic parameters of −ΔH°, K a , K d , N′ and θ, the BHPF-functionalized KIT-5 mesoporous silica exhibits synergistic improvement among

Comparison of Glaciological and Gravimetric Glacier Mass Balance Measurements of Taku and Lemon Creek Glaciers, Southeast Alaska

Science.gov (United States)

Vogler, K.; McNeil, C.; Bond, M.; Getraer, B.; Huxley-Reicher, B.; McNamara, G.; Reinhardt-Ertman, T.; Silverwood, J.; Kienholz, C.; Beedle, M. J.

2017-12-01

Glacier-wide annual mass balances (Ba) have been calculated for Taku (726 km2) and Lemon Creek glaciers (10.2 km2) since 1946 and 1953 respectively. These are the longest mass balance records in North America, and the only Ba time-series available for Southeast Alaska, making them particularly valuable for the global glacier mass balance monitoring network. We compared Ba time-series from Taku and Lemon Creek glaciers to Gravity Recovery and Climate Experiment (GRACE) mascon solutions (1352 and 1353) during the 2004-2015 period to assess how well these gravimetric solutions reflect individual glaciological records. Lemon Creek Glacier is a challenging candidate for this comparison because it is small compared to the 12,100 km2 GRACE mascon solutions. Taku Glacier is equally challenging because its mass balance is stable compared to the negative balances dominating its neighboring glaciers. Challenges notwithstanding, a high correlation between the glaciological and gravimetrically-derived Ba for Taku and Lemon Creek glaciers encourage future use of GRACE to measure glacier mass balance. Additionally, we employed high frequency ground penetrating radar (GPR) to measure the variability of accumulation around glaciological sites to assess uncertainty in our glaciological measurements, and the resulting impact to Ba. Finally, we synthesize this comparison of glaciological and gravimetric mass balance solutions with a discussion of potential sources of error in both methods and their combined utility for measuring regional glacier change during the 21st century.

Comparison of gravimetric and mantle flow solutions for sub-lithopsheric stress modeling and their combination

Science.gov (United States)

Eshagh, Mehdi; Steinberger, Bernhard; Tenzer, Robert; Tassara, Andrés

2018-05-01

Based on Hager and O'Connell's solution to mantle flow equations, the stresses induced by mantle convection are determined using the density and viscosity structure in addition to topographic data and a plate velocity model. The solution to mantle flow equations requires the knowledge of mantle properties that are typically retrieved from seismic information. Large parts of the world are, however, not yet covered sufficiently by seismic surveys. An alternative method of modeling the stress field was introduced by Runcorn. He formulated a direct relation between the stress field and gravity data, while adopting several assumptions, particularly disregarding the toroidal mantle flow component and mantle viscosity variations. A possible way to overcome theoretical deficiencies of Runcorn's theory as well as some practical limitations of applying Hager and O'Connell's theory (in the absence of seismic data) is to combine these two methods. In this study, we apply a least-squares analysis to combine these two methods based on the gravity data inversion constraint on mantle flow equations. In particular, we use vertical gravity gradients from the Gravity field and steady state Ocean Circulation Explorer that are corrected for the gravitational contribution of crustal density heterogeneities prior to applying a localized gravity-gradient inversion. This gravitational contribution is estimated based on combining the Vening Meinesz-Moritz and flexural isostatic theories. Moreover, we treat the non-isostatic effect implicitly by applying a band-limited kernel of the integral equation during the inversion. In numerical studies of modeling, the stress field within the South American continental lithosphere we compare the results obtained after applying Runcorn and Hager and O'Connell's methods as well as their combination. The results show that, according to Hager and O'Connell's (mantle flow) solution, the maximum stress intensity is inferred under the northern Andes

Gravimetric and conductometric studies of the sedimentation kinetics in aqueous dispersions of kaoline

International Nuclear Information System (INIS)

Bulavyin, L.A.; Khrapatij, S.V.; Koval'chuk, V.Yi.; Klepko, V.V.; Lebovka, M.Yi.

2006-01-01

Using gravimetric and conductometric methods, the sedimentation kinetics in aqueous suspensions of Alekseev kaoline has been studied for pH value range from 4 to 10. It has been found that pH increasing leads to the decreasing of mean radii of flocks linearly. We found that sedimentation kinetics for intermediate pH values can be described by scaling equations that crossover time defined transition from a gravitational mechanism of deposition to the diffusion one

Gravimetric water distribution assessment from geoelectrical methods (ERT and EMI) in municipal solid waste landfill.

Science.gov (United States)

Dumont, Gaël; Pilawski, Tamara; Dzaomuho-Lenieregue, Phidias; Hiligsmann, Serge; Delvigne, Frank; Thonart, Philippe; Robert, Tanguy; Nguyen, Frédéric; Hermans, Thomas

2016-09-01

The gravimetric water content of the waste material is a key parameter in waste biodegradation. Previous studies suggest a correlation between changes in water content and modification of electrical resistivity. This study, based on field work in Mont-Saint-Guibert landfill (Belgium), aimed, on one hand, at characterizing the relationship between gravimetric water content and electrical resistivity and on the other hand, at assessing geoelectrical methods as tools to characterize the gravimetric water distribution in a landfill. Using excavated waste samples obtained after drilling, we investigated the influences of the temperature, the liquid phase conductivity, the compaction and the water content on the electrical resistivity. Our results demonstrate that Archie's law and Campbell's law accurately describe these relationships in municipal solid waste (MSW). Next, we conducted a geophysical survey in situ using two techniques: borehole electromagnetics (EM) and electrical resistivity tomography (ERT). First, in order to validate the use of EM, EM values obtained in situ were compared to electrical resistivity of excavated waste samples from corresponding depths. The petrophysical laws were used to account for the change of environmental parameters (temperature and compaction). A rather good correlation was obtained between direct measurement on waste samples and borehole electromagnetic data. Second, ERT and EM were used to acquire a spatial distribution of the electrical resistivity. Then, using the petrophysical laws, this information was used to estimate the water content distribution. In summary, our results demonstrate that geoelectrical methods represent a pertinent approach to characterize spatial distribution of water content in municipal landfills when properly interpreted using ground truth data. These methods might therefore prove to be valuable tools in waste biodegradation optimization projects. Copyright © 2016 Elsevier Ltd. All rights reserved.

Gravimetric Measurements of Filtering Facepiece Respirators Challenged With Diesel Exhaust.

Science.gov (United States)

Satish, Swathi; Swanson, Jacob J; Xiao, Kai; Viner, Andrew S; Kittelson, David B; Pui, David Y H

2017-07-01

Elevated concentrations of diesel exhaust have been linked to adverse health effects. Filtering facepiece respirators (FFRs) are widely used as a form of respiratory protection against diesel particulate matter (DPM) in occupational settings. Previous results (Penconek A, Drążyk P, Moskal A. (2013) Penetration of diesel exhaust particles through commercially available dust half masks. Ann Occup Hyg; 57: 360-73.) have suggested that common FFRs are less efficient than would be expected for this purpose based on their certification approvals. The objective of this study was to measure the penetration of DPM through NIOSH-certified R95 and P95 electret respirators to verify this result. Gravimetric-based penetration measurements conducted using polytetrafluoroethylene (PTFE) and polypropylene (PP) filters were compared with penetration measurements made with a Scanning Mobility Particle Sizer (SMPS, TSI Inc.), which measures the particle size distribution. Gravimetric measurements using PP filters were variable compared to SMPS measurements and biased high due to adsorption of gas phase organic material. Relatively inert PTFE filters adsorbed less gas phase organic material resulting in measurements that were more accurate. To attempt to correct for artifacts associated with adsorption of gas phase organic material, primary and secondary filters were used in series upstream and downstream of the FFR. Correcting for adsorption by subtracting the secondary mass from the primary mass improved the result for both PTFE and PP filters but this correction is subject to 'equilibrium' conditions that depend on sampling time and the concentration of particles and gas phase hydrocarbons. Overall, the results demonstrate that the use of filters to determine filtration efficiency of FFRs challenged with diesel exhaust produces erroneous results due to the presence of gas phase hydrocarbons in diesel exhaust and the tendency of filters to adsorb organic material. Published by

Investigations on vertical crustal movements in the Venezuelan Andes by gravimetric methods

Science.gov (United States)

Drewes, H.

1978-01-01

A precise gravimetric network has been installed in the Venezuelan Andes to study eventual gravity changes due to vertical tectonic movements. The design and the measurements of the network are described and the accuracy is estimated. In the center of the region a local gravity network has been reobserved three times. The detected variations are discussed. In order to obtain a genuine statement as far as possible about the significance of observed gravity changes, requirements for the procedure of monitoring precise gravity networks are pointed out.

Application of InSAR and gravimetric surveys for developing construction codes in zones of land subsidence induced by groundwater extraction: case study of Aguascalientes, Mexico

Directory of Open Access Journals (Sweden)

J. Pacheco-Martínez

2015-11-01

Full Text Available Interferometric Synthetic Aperture Radar (InSAR has become a valuable tool for surface deformation monitoring, including land subsidence associated with groundwater extraction. Another useful tools for studying Earth's surface processes are geophysical methods such as Gravimetry. In this work we present the application of InSAR analysis and gravimetric surveying to generate valuable information for risk management related to land subsidence and surface faulting. Subsidence of the city of Aguascalientes, Mexico is presented as study case. Aguascalientes local governments have addressed land subsidence issues by including new requirements for new constructions projects in the State Urban Construction Code. Nevertheless, the resulting zoning proposed in the code is still subjective and not clearly defined. Our work based on gravimetric and InSAR surveys is aimed for improving the subsidence hazard zoning proposed in the State Urban Code in a more comprehensive way. The study includes a 2007–2011 ALOS InSAR time-series analysis of the Aguascalientes valley, an interpretation of the compete Bouguer gravimetric anomaly of the Aguascalientes urban area, and the application of time series and gravimetric anomaly maps for improve the subsidence hazard zoning of Aguascalientes City.

Lithospheric thickness jumps at the S-Atlantic continental margins from satellite gravity data and modelled isostatic anomalies

Science.gov (United States)

Shahraki, Meysam; Schmeling, Harro; Haas, Peter

2018-01-01

Isostatic equilibrium is a good approximation for passive continental margins. In these regions, geoid anomalies are proportional to the local dipole moment of density-depth distributions, which can be used to constrain the amount of oceanic to continental lithospheric thickening (lithospheric jumps). We consider a five- or three-layer 1D model for the oceanic and continental lithosphere, respectively, composed of water, a sediment layer (both for the oceanic case), the crust, the mantle lithosphere and the asthenosphere. The mantle lithosphere is defined by a mantle density, which is a function of temperature and composition, due to melt depletion. In addition, a depth-dependent sediment density associated with compaction and ocean floor variation is adopted. We analyzed satellite derived geoid data and, after filtering, extracted typical averaged profiles across the Western and Eastern passive margins of the South Atlantic. They show geoid jumps of 8.1 m and 7.0 m for the Argentinian and African sides, respectively. Together with topography data and an averaged crustal density at the conjugate margins these jumps are interpreted as isostatic geoid anomalies and yield best-fitting crustal and lithospheric thicknesses. In a grid search approach five parameters are systematically varied, namely the thicknesses of the sediment layer, the oceanic and continental crusts and the oceanic and the continental mantle lithosphere. The set of successful models reveals a clear asymmetry between the South Africa and Argentine lithospheres by 15 km. Preferred models predict a sediment layer at the Argentine margin of 3-6 km and at the South Africa margin of 1-2.5 km. Moreover, we derived a linear relationship between, oceanic lithosphere, sediment thickness and lithospheric jumps at the South Atlantic margins. It suggests that the continental lithospheres on the western and eastern South Atlantic are thicker by 45-70 and 60-80 km than the oceanic lithospheres, respectively.

Definition of Physical Height Systems for Telluric Planets and Moons

Science.gov (United States)

Tenzer, Robert; Foroughi, Ismael; Sjöberg, Lars E.; Bagherbandi, Mohammad; Hirt, Christian; Pitoňák, Martin

2018-01-01

In planetary sciences, the geodetic (geometric) heights defined with respect to the reference surface (the sphere or the ellipsoid) or with respect to the center of the planet/moon are typically used for mapping topographic surface, compilation of global topographic models, detailed mapping of potential landing sites, and other space science and engineering purposes. Nevertheless, certain applications, such as studies of gravity-driven mass movements, require the physical heights to be defined with respect to the equipotential surface. Taking the analogy with terrestrial height systems, the realization of height systems for telluric planets and moons could be done by means of defining the orthometric and geoidal heights. In this case, however, the definition of the orthometric heights in principle differs. Whereas the terrestrial geoid is described as an equipotential surface that best approximates the mean sea level, such a definition for planets/moons is irrelevant in the absence of (liquid) global oceans. A more natural choice for planets and moons is to adopt the geoidal equipotential surface that closely approximates the geometric reference surface (the sphere or the ellipsoid). In this study, we address these aspects by proposing a more accurate approach for defining the orthometric heights for telluric planets and moons from available topographic and gravity models, while adopting the average crustal density in the absence of reliable crustal density models. In particular, we discuss a proper treatment of topographic masses in the context of gravimetric geoid determination. In numerical studies, we investigate differences between the geodetic and orthometric heights, represented by the geoidal heights, on Mercury, Venus, Mars, and Moon. Our results reveal that these differences are significant. The geoidal heights on Mercury vary from - 132 to 166 m. On Venus, the geoidal heights are between - 51 and 137 m with maxima on this planet at Atla Regio and Beta

Gravimetric preparation and characterization of primary reference solutions of molybdenum and rhodium.

Science.gov (United States)

Kaltenbach, Angela; Noordmann, Janine; Görlitz, Volker; Pape, Carola; Richter, Silke; Kipphardt, Heinrich; Kopp, Gernot; Jährling, Reinhard; Rienitz, Olaf; Güttler, Bernd

2015-04-01

Gravimetrically prepared mono-elemental reference solutions having a well-known mass fraction of approximately 1 g/kg (or a mass concentration of 1 g/L) define the very basis of virtually all measurements in inorganic analysis. Serving as the starting materials of all standard/calibration solutions, they link virtually all measurements of inorganic analytes (regardless of the method applied) to the purity of the solid materials (high-purity metals or salts) they were prepared from. In case these solid materials are characterized comprehensively with respect to their purity, this link also establishes direct metrological traceability to The International System of Units (SI). This, in turn, ensures the comparability of all results on the highest level achievable. Several national metrology institutes (NMIs) and designated institutes (DIs) have been working for nearly two decades in close cooperation with commercial producers on making an increasing number of traceable reference solutions available. Besides the comprehensive characterization of the solid starting materials, dissolving them both loss-free and completely under strict gravimetric control is a challenging problem in the case of several elements like molybdenum and rhodium. Within the framework of the European Metrology Research Programme (EMRP), in the Joint Research Project (JRP) called SIB09 Primary standards for challenging elements, reference solutions of molybdenum and rhodium were prepared directly from the respective metals with a relative expanded uncertainty associated with the mass fraction of U rel(w) methods required to assist with the preparation and as dissemination tools.

Determination of sulfate in thorium salts using gravimetric technique with previous thorium separation

International Nuclear Information System (INIS)

Silva, C.M. da; Pires, M.A.F.

1994-01-01

Available as short communication only. A simple analytical method to analyze sulfates in thorium salt, is presented. The method is based on the thorium separation as hydroxide. The gravimetric technique is used to analyze the sulfate in the filtered as barium sulfate. Using this method, the sulfate separation from thorium has been reach 99,9% yield, and 0,1% precision. This method is applied to thorium salts specifically thorium sulfate, carbonate and nitrate. (author). 5 refs, 2 tabs

Comparison of gravimetric and gas chromatographic methods for assessing performance of textile materials against liquid pesticide penetration.

Science.gov (United States)

Shaw, Anugrah; Abbi, Ruchika

2004-01-01

Penetration of liquid pesticides through textile materials is a criterion for determining the performance of protective clothing used by pesticide handlers. The pipette method is frequently used to apply liquid pesticides onto textile materials to measure penetration. Typically, analytical techniques such as Gas Chromatography (GC) are used to measure percentage penetration. These techniques are labor intensive and costly. A simpler gravimetric method was developed, and tests were conducted to compare the gravimetric and GC methods of analysis. Three types of pesticide formulations and 4 fabrics were used for the study. Diluted pesticide formulations were pipetted onto the test specimens and percentage penetration was measured using the 2 methods. For homogeneous formulation, the results of the two methods were fairly comparable. However, due to the filtering action of the textile materials, there were differences in the percentage penetration between the 2 methods for formulations that were not homogeneous.

Simplified method for gravimetric determination of zirconium or hafnium with α-hydroxy carboxylic acids

International Nuclear Information System (INIS)

Barbieri, R.S.; Rocha, J.C.; Terra, V.R.; Marques Netto, A.

1989-01-01

The conditions for gravimetric determination of zirconium or hafnium by glicoloc acids derivatives were studied by thermogravimetric analysis. The method utilized shownd that after precipitation, washing and drying of precipitates at 150 o C, the resulting solid was weighed in the form of [M (RCH(OH)COO) 4 ] (M = Zr, Hf; R + C 6 H 5 , β-C 10 H 7 , p-BrC 6 H 4 ). (author)

Geoid and gravity anomaly data of conjugate regions of Bay of Bengal and Enderby Basin: New constraints on breakup and early spreading history between India and Antarctica

Digital Repository Service at National Institute of Oceanography (India)

Krishna, K.S.; Michael, L.; Bhattacharyya, R.; Majumdar, T.J.

the anomalies. Since the magnetic anomalies in the western Enderby Basin have lower amplitude, Gaina et al. (2007) could not identify the anomalies with confidence and found difficulty to correlate the spreading history with that of the central and eastern... Geoid and gravity anomaly data of conjugate regions of Bay of Bengal and Enderby Basin – new constraints on breakup and early spreading history between India and Antarctica K.S. Krishna*, Laju Michael National Institute of Oceanography, Council...

Determination of molybdenum by the gravimetric plumbate method (with the molybdenum content from 50 % and above)

International Nuclear Information System (INIS)

Stepin, V.V.; Kurbatova, V.I.; Fedorova, N.D.

1980-01-01

A gravimetric method of molybdenum determination in ferromolybdenum (Mo content from 50% and higher) after its dissolving in HNO 3 is developed. The method is based on Mo deposition in acetic acid solution in the form of molybdenum oxide lead after separation of Fe and other interfering elements with sodium hydroxide [ru

A binder-free NiCo2O4 nanosheet/3D elastic N-doped hollow carbon nanotube sponge electrode with high volumetric and gravimetric capacitances for asymmetric supercapacitors.

Science.gov (United States)

Tong, Hao; Yue, Shihong; Lu, Liang; Jin, Fengqiao; Han, Qiwei; Zhang, Xiaogang; Liu, Jie

2017-11-09

To increase the volumetric and gravimetric capacitances of supercapacitors, a new class of electrode materials with high electrochemical activity and favorable structures is extremely desired. In this work, a hollow novel nitrogen-doped 3D elastic single-walled carbon nanotube sponge (NSCS) which is ultra lightweight with the lowest density of 0.8 mg cm -3 , and has a high open surface structure for electrolyte accessibility and excellent compressible properties as the electrode scaffold has been successfully fabricated by the pyrolysis method which could produce the carbon nanotube sponge easily on a large scale without high-cost and time-consuming processes. Moreover, a NiCo 2 O 4 nanosheet supported on the NSCS has been successfully fabricated. The highest volumetric and gravimetric capacitance of this electrode is 790 F cm -3 at 1.43 g cm -3 and 1618 F g -1 at 0.54 g cm -3 with excellent cycling stability. The density of NiCo 2 O 4 /NSCS electrode was adjusted by mechanical compression and the most favorable density of the film for both high volumetric and gravimetric capacitances obtained was 1.21 g cm -3 . The thick NiCo 2 O 4 /NSCS film of 72 μm has been fabricated at this favorable density, presenting both high volumetric and gravimetric capacitances of 597 F cm -3 and 1074 F g -1 at 1 A g -1 , respectively, indicating that the structure of the NSCS is extremely feasible for obtaining a thick film electrode with excellent volumetric and gravimetric capacitances. Furthermore, an asymmetric supercapacitor of NiCo 2 O 4 /NSCS//NGN/CNTs was fabricated, exhibiting a high gravimetric energy density of 47.65 W h kg -1 at 536 W kg -1 and a volumetric energy density of 33.44 W h L -1 at 376.16 W L -1 .

A gravimetric and an X-ray fluorescence method for the determination of rubidium in Rb2U(SO4)3

International Nuclear Information System (INIS)

Mudher, K.D.S.; Krishnan, K.; Jayadevan, N.C.

1993-01-01

Chemical characterization of rubidium uranium(IV) trisulfate, RB 2 U(SO 4 ) 3 , a new chemical assay standard for uranium requires accurate analysis of rubidium. A gravimetric and an X-ray fluorescence method (XRF) for the determination of rubidium in this compound are described. In the gravimetric method, rubidium is determined as Rb 2 Na[Co(NO 2 ) 6 ].H 2 O without separating uranium with a precision of the order of ±0.5%. In the XRF method, the concentration ratio of rubidium to uranium, C Rb /C U , is determined in the solid samples by the binary ratio method using calibration between intensity ratios (I Rb /I U ) and concentration ratios (C Rb /C U ). (author) 6 refs.; 2 figs.; 3 tabs

Joint inversion of shear wave travel time residuals and geoid and depth anomalies for long-wavelength variations in upper mantle temperature and composition along the Mid-Atlantic Ridge

Science.gov (United States)

Sheehan, Anne F.; Solomon, Sean C.

1991-01-01

Measurements were carried out for SS-S differential travel time residuals for nearly 500 paths crossing the northern Mid-Atlantic Ridge, assuming that the residuals are dominated by contributions from the upper mantle near the surface bounce point of the reflected phase SS. Results indicate that the SS-S travel time residuals decrease linearly with square root of age, to an age of 80-100 Ma, in general agreement with the plate cooling model. A joint inversion was formulated of travel time residuals and geoid and bathymetric anomalies for lateral variation in the upper mantle temperature and composition. The preferred inversion solutions were found to have variations in upper mantle temperature along the Mid-Atlantic Ridge of about 100 K. It was calculated that, for a constant bulk composition, such a temperature variation would produce about a 7-km variation in crustal thickness, larger than is generally observed.

An NMR relaxometry and gravimetric study of gelatin-free aqueous polyacrylamide dosimeters

International Nuclear Information System (INIS)

Babic, Steven; Schreiner, L John

2006-01-01

In conformal radiation therapy, a high dose of radiation is given to a target volume to increase the probability of cure, and care is taken to minimize the dose to surrounding healthy tissue. The techniques used to achieve this are very complicated and the precise verification of the resulting three-dimensional (3D) dose distribution is required. Polyacrylamide gelatin (PAG) dosimeters with magnetic resonance imaging and optical computed tomography scanning provide the required 3D dosimetry with high spatial resolution. Many basic studies have characterized these chemical dosimeters that polymerize under irradiation. However, the investigation of the fundamental properties of the radiation-induced polymerization in PAG dosimeters is complicated by the presence of the background gelatin matrix. In this work, a gelatin-free model system for the study of the basic radiation-induced polymerization in PAG dosimeters has been developed. Experiments were performed on gelatin-free dosimeters, named aqueous polyacrylamide (APA) dosimeters, containing equal amounts of acrylamide and N,N'-methylene-bisacrylamide. The APA dosimeters were prepared with four different total monomer concentrations (2, 4, 6 and 8% by weight). Nuclear magnetic resonance (NMR) spin-spin and spin-lattice proton relaxation measurements at 20 MHz, and gravimetric analyses performed on all four dosimeters, show a continuous degree of polymerization over the dose range of 0-25 Gy. The developed NMR model explains the relationship observed between the relaxation data and the amount of crosslinked polymer formed at each dose. This model can be extended with gelatin relaxation data to provide a fundamental understanding of radiation-induced polymerization in the conventional PAG dosimeters

GRAVIMETRIC-DETERMINATION OF THE WATER CONCENTRATION IN WHOLE-BLOOD, PLASMA AND ERYTHROCYTES AND CORRELATIONS WITH HEMATOLOGICAL AND CLINICOCHEMICAL PARAMETERS

NARCIS (Netherlands)

LIJNEMA, TH; HUIZENGA, [No Value; JAGER, J; MACKOR, AJ; GIPS, CH

1993-01-01

We have assessed gravimetric methods for determination of intravascular water, established whole blood-, plasma- and erythrocyte water reference values in a healthy volunteer group (n = 97, 48 females) and correlated these variables with 30 simultaneous hematological, clinicochemical and body

Highly Selective Polypyrrole MIP-Based Gravimetric and Electrochemical Sensors for Picomolar Detection of Glyphosate

Directory of Open Access Journals (Sweden)

Zouhour Mazouz

2017-11-01

Full Text Available There is a global debate and concern about the use of glyphosate (Gly as an herbicide. New toxicological studies will determine its use in the future under new strict conditions or its replacement by alternative synthetic or natural herbicides. In this context, we designed biomimetic polymer sensing layers for the selective molecular recognition of Gly. Towards this end, complementary surface acoustic wave (SAW and electrochemical sensors were functionalized with polypyrrole (PPy-imprinted polymer for the selective detection of Gly. Their corresponding limits of detection were on the order of 1 pM, which are among the lowest values ever reported in literature. The relevant dissociation constants between PPy and Gly were estimated at [Kd1 = (0.7 ± 0.3 pM and Kd2 = (1.6 ± 1.4 µM] and [Kd1 = (2.4 ± 0.9 pM and Kd2 = (0.3 ± 0.1 µM] for electrochemical and gravimetric measurements, respectively. Quantum chemical calculations permitted to estimate the interaction energy between Gly and PPy film: ΔE = −145 kJ/mol. Selectivity and competitivity tests were investigated with the most common pesticides. This work conclusively shows that gravimetric and electrochemical results indicate that both MIP-based sensors are perfectly able to detect and distinguish glyphosate without any ambiguity.

Alternatives to the gravimetric method for quantification of diesel particulate matter near the lower level of detection.

Science.gov (United States)

Swanson, Jacob; Kittelson, David; Pui, David; Watts, Winthrop

2010-10-01

This paper is part of the Journal of the Air & Waste Management Association's 2010 special issue on combustion aerosol measurements. The issue is a combination of papers that synthesize and evaluate ideas and perspectives that were presented by experts at a series of workshops sponsored by the Coordinating Research Council that aimed to evaluate the current and future status of diesel particulate matter (DPM) measurement. Measurement of DPM is a complex issue with many stakeholders, including air quality management and enforcement agencies, engine manufacturers, health experts, and climatologists. Adoption of the U.S. Environmental Protection Agency 2007 heavy-duty engine DPM standards posed a unique challenge to engine manufacturers. The new standards reduced DPM emissions to the point that improvements to the gravimetric method were required to increase the accuracy and the sensitivity of the measurement. Despite these improvements, the method still has shortcomings. The objectives of this paper are to review the physical and chemical properties of DPM that make gravimetric measurement difficult at very low concentrations and to review alternative metrics and methods that are potentially more accurate, sensitive, and specific. Particle volatility, size, surface area, and number metrics are considered, as well as methods to quantify them. Although the authors believe that an alternative method is required to meet the needs of engine manufacturers, the methods reviewed in the paper are applicable to other areas where the gravimetric method detection limit is approached and greater accuracy and sensitivity are required. The paper concludes by suggesting a method to measure active surface area, combined with a method to separate semi-volatile and solid fractions to further increase the specificity of the measurement, has potential for reducing the lower detection limit of DPM and enabling engine manufacturers to reduce DPM emissions in the future.

Gravimetric determination of carbon in uranium-plutonium carbide materials

International Nuclear Information System (INIS)

Kavanaugh, H.J.; Dahlby, J.W.; Lovell, A.P.

1979-12-01

A gravimetric method for determining carbon in uranium-plutonium carbide materials was developed to analyze six samples simultaneously. The samples are burned slowly in an oxygen atmosphere at approximately 900 0 C, and the gases generated are passed through Schuetze's oxidizing reagent (iodine pentoxide on silica gel) to assure quantitative oxidation of the CO to CO 2 . The CO 2 is collected on Ascarite and weighed. This method was tested using a tungsten carbide reference material (NBS-SRM-276) and a (U,Pu)C sample. For 42 analyses of the tungsten carbide, which has a certified carbon content of 6.09%, an average value of 6.09% was obtained with a standard deviation of 0.01 7 % or a relative standard deviation of 0.28%. For 17 analyses of the (U,Pu)C sample, an average carbon content of 4.97% was found with a standard deviation of 0.01 2 % or a relative standard deviation of 0.24%

[Evaluation of the AOAC 985.29 enzimic gravimetric method for determination of dietary fiber in oat and corn grains].

Science.gov (United States)

da Silva, Leila Picolli; Ciocca, Maria de Lourdes Santorio; Furlong, Eliana Badiale

2003-12-01

The precision attributes and use of the enzymatic-gravimetric method of Prosky et al. (1992) (AOAC 985.29) were evaluated using corn (BR 5202 Pampa) and oat (UFRGS 15) samples. The effect of laboratory batches carried out in different days were evaluated in six laboratory batches, using for each material one duplicate for total fiber (FT) determination, one duplicate for insoluble fiber (FI) determination and blank ones for FT and for FI (both in duplicate). In order to characterize repetitive aspects, five other FT and FI determinations added to each sample were evaluated, summing up 11 data. The low coefficients of variation in the first six batches were considered acceptable as an expression of expected total intralaboratory variation. The repetitive of the method was considered good for FT determinations (CVs gravimetric corrections varies with the kind of the sample and is especially influenced by the protein content.

EGM2008

African Journals Online (AJOL)

Nana Kwasi Peprah

(EGM2008) – A Case Study ... Ghana's local geodetic reference network which is based on the War Office 1926 ... The study concluded that, the recent geoid model can be applied in UMaT and the ... regional or local geoid models after modelling the differences between the ...... Conference 2009, Salt Lake City, UT USA.

Modelling airborne gravity data by means of adapted Space-Wise approach

Science.gov (United States)

Sampietro, Daniele; Capponi, Martina; Hamdi Mansi, Ahmed; Gatti, Andrea

2017-04-01

Regional gravity field modelling by means of remove - restore procedure is nowadays widely applied to predict grids of gravity anomalies (Bouguer, free-air, isostatic, etc.) in gravimetric geoid determination as well as in exploration geophysics. Considering this last application, due to the required accuracy and resolution, airborne gravity observations are generally adopted. However due to the relatively high acquisition velocity, presence of atmospheric turbulence, aircraft vibration, instrumental drift, etc. airborne data are contaminated by a very high observation error. For this reason, a proper procedure to filter the raw observations both in the low and high frequency should be applied to recover valuable information. In this work, a procedure to predict a grid or a set of filtered along track gravity anomalies, by merging GGM and airborne dataset, is presented. The proposed algorithm, like the Space-Wise approach developed by Politecnico di Milano in the framework of GOCE data analysis, is based on a combination of along track Wiener filter and Least Squares Collocation adjustment and properly considers the different altitudes of the gravity observations. Among the main differences with respect to the satellite application of the Space-Wise approach there is the fact that, while in processing GOCE data the stochastic characteristics of the observation error can be considered a-priori well known, in airborne gravimetry, due to the complex environment in which the observations are acquired, these characteristics are unknown and should be retrieved from the dataset itself. Some innovative theoretical aspects focusing in particular on the theoretical covariance modelling are presented too. In the end, the goodness of the procedure is evaluated by means of a test on real data recovering the gravitational signal with a predicted accuracy of about 0.25 mGal.

Laser metrology for a next generation gravimetric mission

Science.gov (United States)

Mottini, Sergio; Biondetti, Giorgio; Cesare, Stefano; Castorina, Giuseppe; Musso, Fabio; Pisani, Marco; Leone, Bruno

2017-11-01

Within the ESA technology research project "Laser Interferometer High Precision tracking for LEO", Thales Alenia Space Italia is developing a laser metrology system for a Next Generation Gravimetric Mission (NGGM) based on satellite-to-satellite tracking. This technique is based on the precise measurement of the displacement between two satellites flying in formation at low altitude for monitoring the variations of Earth's gravity field at high resolution over a long time period. The laser metrology system that has been defined for this mission consists of the following elements: • an heterodyne Michelson interferometer for measuring the distance variation between retroreflectors positioned on the two satellites; • an angle metrology for measuring the orientation of the laser beam in the reference frames of the two satellites; • a lateral displacement metrology for measuring the deviations of the laser beam axis from the target retro-reflector. The laser interferometer makes use of a chopped measurement beam to avoid spurious signals and nonlinearity caused by the unbalance between the strong local beam and the weak return beam. The main results of the design, development and test activities performed on the breadboard of the metrology system are summarized in this paper.

Metal-Organic Frameworks for Resonant-Gravimetric Detection of Trace-Level Xylene Molecules.

Science.gov (United States)

Xu, Tao; Xu, Pengcheng; Zheng, Dan; Yu, Haitao; Li, Xinxin

2016-12-20

As one of typical VOCs, xylene is seriously harmful to human health. Nowadays, however, there is really lack of portable sensing method to directly detect environmental xylene that has chemical inertness. Especially when the concentration of xylene is lower than the human olfactory threshold of 470 ppb, people are indeed hard to be aware of and avoid this harmful vapor. Herein the metal-organic framework (MOF) of HKUST-1 is first explored for sensing to the nonpolar molecule of p-xylene. And the sensing mechanism is identified that is via host-guest interaction of MOF with xylene molecule. By loading MOFs on mass-gravimetric resonant-cantilevers, sensing experiments for four MOFs of MOF-5, HKUST-1, ZIF-8, and MOF-177 approve that HKUST-1 has the highest sensitivity to p-xylene. The resonant-gravimetric sensing experiments with our HKUST-1 based sensors have demonstrated that trace-level p-xylene of 400 ppb can be detected that is lower than the human olfactory threshold of 470 ppb. We analyze that the specificity of HKUST-1 to xylene comes from Cu 2+ -induced moderate Lewis acidity and the "like dissolves like" interaction of the benzene ring. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) is used to elucidate the adsorbing/sensing mechanism of HKUST-1 to p-xylene, where p-xylene adsorbing induced blue-shift phenomenon is observed that confirms the sensing mechanism. Our study also indicates that the sensor shows good selectivity to various kinds of common interfering gases. And the long-term repeatability and stability of the sensing material are also approved for the usage/storage period of two months. This research approves that the MOF materials exhibit potential usages for high performance chemical sensors applications.

Thermo Gravimetric and Differential Thermal Analysis of Clay of Western Rajasthan (india)

Science.gov (United States)

Shekhawat, M. S.

The paper presents the study of thermo gravimetric and differential thermal analysis of blended clay. Western part of Rajasthan (India) is rich resource of Ball clays and it is mainly used by porcelain, sanitary ware, and tile industry. The quality and grade of clay available in the region vary from one deposit to other. To upgrade the fired colour and strength properties, different variety of clays may be blended together. The paper compares the results of thermal analysis one of blended clay B2 with reference clay of Ukraine which is imported by industries owners. The result revealed that the blended clay is having mineral kaolinite while the Ukrainian clay is Halloysite.

[Determination of total, soluble and insoluble dietary fiber in foods by enzymatic-gravimetric method].

Science.gov (United States)

Yang, X; Yang, Y; Zhou, R; Bian, L

2001-11-01

For studying the contents of dietary fiber in general foods and functional foods, a enzymatic-gravimetric method recommended by AOAC was established in our laboratory. The method for the determination of total, soluble and insoluble dietary fiber in foods and functional foods could be used for many other kind of foods. The relative standard deviations (RSD) of reproducibility between-run and within-run were 2.04%-7.85%, 3.42%-55.23% respectively. The repeatability of the methods was good, and the methods are suitable for many foods.

Analysis of the thermal profiles and the charcoal gravimetric yield in three variations of rectangular brick

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Rogerio Lima Mota de; Alves Junior, Edson; Mulina, Bruno Henrique Oliveira; Borges, Valerio Luiz; Carvalho, Solidonio Rodrigues de [Federal University of Uberlandia - UFU, MG (Brazil). School of Mechanical Engineering - FEMEC], e-mails: rogerio@mecanica.ufu.br, edson@mec.ufu.br, vlborges@mecanica.ufu.br, srcarvalho@mecanica.ufu.br

2010-07-01

Charcoal assumes a major role in Brazilian economic scenario. The procedure for obtaining charcoal consists in carbonization of wood at certain specific temperatures in kilns. This ancient process has a few joined technologies and the kilns for such practice do not have any control instruments, in their great majority, becoming dependent on the ability of its operators. However, in recent decades several studies have been developed to improve the practice as well as the equipment that involve and control the stages of charcoal production. In this sense, this work proposes the analysis of the thermal profiles and the gravimetric yield in three variations of a rectangular brick kiln called RAC220: traditional (without any type of instrumentation), instrumented with thermal sensors (RTD PT100) and adapted with gasifier. The goal is to correlate temperature, gravimetric yield and quality of the produced charcoal. Immediate analyses were performed to determine the amount of fixed carbon, volatile gases and ashes contents in charcoal. Through such measurement procedures, together with statistical analysis, the aim is to identify an important tool to reduce the time of charcoal production and also contributes to minimize losses and to increase the thermal efficiency of the production process. (author)

Structural features of the southern Tulum Fault System, western central Argentina, through gravimetric data and geomorphologic analyses

Science.gov (United States)

Rodríguez, Aixa I.; Christiansen, Rodolfo O.; Suvires, Graciela M.; Lince Klinger, Federico; Martinez, M. Patricia

2016-12-01

A gravimetric analysis over the Tulum Valley was made. This data was used to reveal the structural setting of the Tulum Fault System situated in the southeastern part of San Juan province in the arid western part of Argentina. This system is the boundary between two geological provinces, the eastern Precordillera Oriental and the Sierras Pampeanas Occidentales. Gravity data was processed using upward continuation and vertical derivative filters and all the results were compared with the geomorphological and the drainage systems maps of the area. Our assessment confirms the presence of two structures in the Pampeano basement with positive anomalies similar to those found in Valdivia and Barboza hills, two important depocenters with low gravimetric gradients separated by a zone with higher gravity anomalies than the depocenters to the east and west. In view of this, a structural map is proposed for the area. This system is important not only because it is the boundary between two geological provinces and has significance regarding regional tectonic issues but also because it controls the surface drainage, soils distribution and groundwater flow of the Tulum basin conditioning the land use distribution.

Characterization and Gravimetric Analysis of the Dissolved Quartz in the Conversion of Coal Fly Ash to Sodalite

International Nuclear Information System (INIS)

Mohd Hilmi Mohamed; Zainab Ramli

2012-01-01

Coal fly ash (CFA) is a waste product produced from the electrical power plant and hazardous towards the environment. However, the high composition of silica and alumina in the CFA makes it useful as raw materials in the zeolite synthesis. However, the presence of silica in the form of quartz in the CFA does not facilitate the transformation of CFA to zeolite at 100 degree Celsius and autogeneous pressure. In this study, CFA was converted to zeolites in various NaOH concentrations by microwave heating at various heating time. All synthesized product were characterized by X-ray diffraction (XRD), and gravimetric analysis. XRD has shown that quite pure sodalite in nano size has been formed as early as 15 minutes and increase with time. Prolong heating up to 45 minutes has reduced the content of quartz to ca 20 %. Gravimetric analysis performed on the liquor of the reaction showed that the dissolved silica decrease with increase of heating time indicating that most of the dissolved quartz is used up to form sodalite framework. Hence, quartz of CFA did help in enhancing the crystallinity of the formed sodalite after prolong heating. (author)

Surface and subsurface continuous gravimetric monitoring of groundwater recharge processes through the karst vadose zone at Rochefort Cave (Belgium)

Science.gov (United States)

Watlet, A.; Van Camp, M. J.; Francis, O.; Poulain, A.; Hallet, V.; Triantafyllou, A.; Delforge, D.; Quinif, Y.; Van Ruymbeke, M.; Kaufmann, O.

2017-12-01

Ground-based gravimetry is a non-invasive and integrated tool to characterize hydrological processes in complex environments such as karsts or volcanoes. A problem in ground-based gravity measurements however concerns the lack of sensitivity in the first meters below the topographical surface, added to limited infiltration below the gravimeter building (umbrella effect). Such limitations disappear when measuring underground. Coupling surface and subsurface gravity measurements therefore allow isolating hydrological signals occurring in the zone between the two gravimeters. We present a coupled surface/subsurface continuous gravimetric monitoring of 2 years at the Rochefort Cave Laboratory (Belgium). The gravity record includes surface measurements of a GWR superconducting gravimeter and subsurface measurements of a Micro-g LaCoste gPhone gravimeter, installed in a cave 35 m below the surface station. The recharge of karstic aquifers is extremely complex to model, mostly because karst hydrological systems are composed of strongly heterogeneous flows. Most of the problem comes from the inadequacy of conventional measuring tools to correctly sample such heterogeneous media, and particularly the existence of a duality of flow types infiltrating the vadose zone: from rapid flows via open conduits to slow seepage through porous matrix. Using the surface/subsurface gravity difference, we were able to identify a significant seasonal groundwater recharge within the karst vadose zone. Seasonal or perennial perched reservoirs have already been proven to exist in several karst areas due to the heterogeneity of the porosity and permeability gradient in karstified carbonated rocks. Our gravimetric experiment allows assessing more precisely the recharge processes of such reservoirs. The gravity variations were also compared with surface and in-cave hydrogeological monitoring (i.e. soil moisture, in-cave percolating water discharges, water levels of the saturated zone). Combined

Studying the Representation Accuracy of the Earth's Gravity Field in the Polar Regions Based on the Global Geopotential Models

Science.gov (United States)

Koneshov, V. N.; Nepoklonov, V. B.

2018-05-01

The development of studies on estimating the accuracy of the Earth's modern global gravity models in terms of the spherical harmonics of the geopotential in the problematic regions of the world is discussed. The comparative analysis of the results of reconstructing quasi-geoid heights and gravity anomalies from the different models is carried out for two polar regions selected within a radius of 1000 km from the North and South poles. The analysis covers nine recently developed models, including six high-resolution models and three lower order models, including the Russian GAOP2012 model. It is shown that the modern models determine the quasi-geoid heights and gravity anomalies in the polar regions with errors of 5 to 10 to a few dozen cm and from 3 to 5 to a few dozen mGal, respectively, depending on the resolution. The accuracy of the models in the Arctic is several times higher than in the Antarctic. This is associated with the peculiarities of gravity anomalies in every particular region and with the fact that the polar part of the Antarctic has been comparatively less explored by the gravity methods than the polar Arctic.

Evaluation of real-time data obtained from gravimetric preparation of antineoplastic agents shows medication errors with possible critical therapeutic impact: Results of a large-scale, multicentre, multinational, retrospective study.

Science.gov (United States)

Terkola, R; Czejka, M; Bérubé, J

2017-08-01

Medication errors are a significant cause of morbidity and mortality especially with antineoplastic drugs, owing to their narrow therapeutic index. Gravimetric workflow software systems have the potential to reduce volumetric errors during intravenous antineoplastic drug preparation which may occur when verification is reliant on visual inspection. Our aim was to detect medication errors with possible critical therapeutic impact as determined by the rate of prevented medication errors in chemotherapy compounding after implementation of gravimetric measurement. A large-scale, retrospective analysis of data was carried out, related to medication errors identified during preparation of antineoplastic drugs in 10 pharmacy services ("centres") in five European countries following the introduction of an intravenous workflow software gravimetric system. Errors were defined as errors in dose volumes outside tolerance levels, identified during weighing stages of preparation of chemotherapy solutions which would not otherwise have been detected by conventional visual inspection. The gravimetric system detected that 7.89% of the 759 060 doses of antineoplastic drugs prepared at participating centres between July 2011 and October 2015 had error levels outside the accepted tolerance range set by individual centres, and prevented these doses from reaching patients. The proportion of antineoplastic preparations with deviations >10% ranged from 0.49% to 5.04% across sites, with a mean of 2.25%. The proportion of preparations with deviations >20% ranged from 0.21% to 1.27% across sites, with a mean of 0.71%. There was considerable variation in error levels for different antineoplastic agents. Introduction of a gravimetric preparation system for antineoplastic agents detected and prevented dosing errors which would not have been recognized with traditional methods and could have resulted in toxicity or suboptimal therapeutic outcomes for patients undergoing anticancer treatment. �

Comparison of Respirable Mass Concentrations Measured by a Personal Dust Monitor and a Personal DataRAM to Gravimetric Measurements.

Science.gov (United States)

Halterman, Andrew; Sousan, Sinan; Peters, Thomas M

2017-12-15

In 2016, the Mine Safety and Health Administration required the use of continuous monitors to measure respirable dust in mines and better protect miner health. The Personal Dust Monitor, PDM3700, has met stringent performance criteria for this purpose. In a laboratory study, respirable mass concentrations measured with the PDM3700 and a photometer (personal DataRam, pDR-1500) were compared to those measured gravimetrically for five aerosols of varying refractive index and density (diesel exhaust fume, welding fume, coal dust, Arizona road dust (ARD), and salt [NaCl] aerosol) at target concentrations of 0.38, 0.75, and 1.5 mg m-3. For all aerosols except coal dust, strong, near-one-to-one, linear relationships were observed between mass concentrations measured with the PDM3700 and gravimetrically (diesel fume, slope = 0.99, R2 = 0.99; ARD, slope = 0.98, R2 = 0.99; and NaCl, slope = 0.95, R2 = 0.99). The slope deviated substantially from unity for coal dust (slope = 0.55; R2 = 0.99). Linear relationships were also observed between mass concentrations measured with the pDR-1500 and gravimetrically, but one-to-one behavior was not exhibited (diesel fume, slope = 0.23, R2 = 0.76; coal dust, slope = 0.54, R2 = 0.99; ARD, slope = 0.61, R2 = 0.99; NaCl, slope = 1.14, R2 = 0.98). Unlike the pDR-1500, mass concentrations measured with the PDM3700 appear independent of refractive index and density, suggesting that it could have applications in a variety of occupational settings. © The Author(s) 2017. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Airborne Hyperspectral Evaluation of Maximum Gross Photosynthesis, Gravimetric Water Content, and CO2 Uptake Efficiency of the Mer Bleue Ombrotrophic Peatland

Directory of Open Access Journals (Sweden)

J. Pablo Arroyo-Mora

2018-04-01

Full Text Available Peatlands cover a large area in Canada and globally (12% and 3% of the landmass, respectively. These ecosystems play an important role in climate regulation through the sequestration of carbon dioxide from, and the release of methane to, the atmosphere. Monitoring approaches, required to understand the response of peatlands to climate change at large spatial scales, are challenged by their unique vegetation characteristics, intrinsic hydrological complexity, and rapid changes over short periods of time (e.g., seasonality. In this study, we demonstrate the use of multitemporal, high spatial resolution (1 m2 hyperspectral airborne imagery (Compact Airborne Spectrographic Imager (CASI and Shortwave Airborne Spectrographic Imager (SASI sensors for assessing maximum instantaneous gross photosynthesis (PGmax in hummocks, and gravimetric water content (GWC and carbon uptake efficiency in hollows, at the Mer Bleue ombrotrophic bog. We applied empirical models (i.e., in situ data and spectral indices and we derived spatial and temporal trends for the aforementioned variables. Our findings revealed the distribution of hummocks (51.2%, hollows (12.7%, and tree cover (33.6%, which is the first high spatial resolution map of this nature at Mer Bleue. For hummocks, we found growing season PGmax values between 8 μmol m−2 s−1 and 12 μmol m−2 s−1 were predominant (86.3% of the total area. For hollows, our results revealed, for the first time, the spatial heterogeneity and seasonal trends for gravimetric water content and carbon uptake efficiency for the whole bog.

A high-precision digital astrogeodetic traverse in an area of steep geoid gradients close to the coast of Perth, Western Australia

Science.gov (United States)

Schack, P.; Hirt, C.; Hauk, M.; Featherstone, W. E.; Lyon, T. J.; Guillaume, S.

2018-01-01

We present results from a new vertical deflection (VD) traverse observed in Perth, Western Australia, which is the first of its kind in the Southern Hemisphere. A digital astrogeodetic QDaedalus instrument was deployed to measure VDs with {˜ } 0.2'' precision at 39 benchmarks with a {{˜ }}1 km spacing. For the conversion of VDs to quasigeoid height differences, the method of astronomical-topographical levelling was applied, based on topographical information from the Shuttle Radar Topography Mission. The astronomical quasigeoid heights are in 20-30 mm (RMS) agreement with three independent gravimetric quasigeoid models, and the astrogeodetic VDs agree to 0.2-0.3'' (north-south) and 0.6-0.9'' (east-west) RMS. Tilt-like biases of {˜ }1 mm over {˜ }1 km are present for all quasigeoid models within {˜ }20 km of the coastline, suggesting inconsistencies in the coastal zone gravity data. The VD campaign in Perth was designed as a low-cost effort, possibly allowing replication in other Southern Hemisphere countries (e.g., Asia, Africa, South America and Antarctica), where VD data are particularly scarce.

Experimental aspects of buoyancy correction in measuring reliable highpressure excess adsorption isotherms using the gravimetric method.

Science.gov (United States)

Nguyen, Huong Giang T; Horn, Jarod C; Thommes, Matthias; van Zee, Roger D; Espinal, Laura

2017-12-01

Addressing reproducibility issues in adsorption measurements is critical to accelerating the path to discovery of new industrial adsorbents and to understanding adsorption processes. A National Institute of Standards and Technology Reference Material, RM 8852 (ammonium ZSM-5 zeolite), and two gravimetric instruments with asymmetric two-beam balances were used to measure high-pressure adsorption isotherms. This work demonstrates how common approaches to buoyancy correction, a key factor in obtaining the mass change due to surface excess gas uptake from the apparent mass change, can impact the adsorption isotherm data. Three different approaches to buoyancy correction were investigated and applied to the subcritical CO 2 and supercritical N 2 adsorption isotherms at 293 K. It was observed that measuring a collective volume for all balance components for the buoyancy correction (helium method) introduces an inherent bias in temperature partition when there is a temperature gradient (i.e. analysis temperature is not equal to instrument air bath temperature). We demonstrate that a blank subtraction is effective in mitigating the biases associated with temperature partitioning, instrument calibration, and the determined volumes of the balance components. In general, the manual and subtraction methods allow for better treatment of the temperature gradient during buoyancy correction. From the study, best practices specific to asymmetric two-beam balances and more general recommendations for measuring isotherms far from critical temperatures using gravimetric instruments are offered.

Determination of hydrogen in zirconium hydride and uranium-zirconium hydride by inert gas exraction-gravimetric method

International Nuclear Information System (INIS)

Hoshino, Akira; Iso, Shuichi

1976-01-01

An inert gas extraction-gravimetric method has been applied to the determination of hydrogen in zirconium hydride and uranium-zirconium hydride which are used as neutron moderator and fuel of nuclear safety research reactor (NSRR), respectively. The sample in a graphite-enclosed quartz crucible is heated inductively to 1200 0 C for 20 min in a helium stream. Hydrogen liberated from the sample is oxidized to water by copper(I) oxide-copper(II) oxide at 400 0 C, and the water is determined gravimetrically by absorption in anhydrone. The extraction curves of hydrogen for zirconium hydride and uranium-zirconium hydride samples are shown in Figs. 2 and 3. Hydrogen in the samples is extracted quantitatively by heating at (1000 -- 1250) 0 C for (10 -- 40) min. Recoveries of hydrogen in the case of zirconium hydride were examined as follows: a weighed zirconium rod (5 phi x 6 mm, hydrogen -5 Torr. After the chamber was filled with purified hydrogen to 200 Torr, the rod was heated to 400 0 C for 15 h, and again weighed to determine the increase in weight. Hydrogen in the rod was then determined by the proposed method. The results are in excellent agreement with the increase in weight as shown in Table 1. Analytical results of hydrogen in zirconium hydride samples and an uranium-zirconium hydride sample are shown in Table 2. (auth.)

Comparison between thermo balance and classic gravimetric method for determination of suspended solids in sludge from wastewater treatment plant

International Nuclear Information System (INIS)

Bruzzone, E.

2009-01-01

In this paper two methods for determination of suspended solids in sludge from wastewater treatment plants (activated, thickened and dry, in a range from 0.1 to 20-25%) are compared. Results are similar from statistic point of view between classic gravimetric method and thermo balance method. However the later seems better for its rapid and easy execution. [it

Mapping of sea bottom topography over western offshore, India using TOPEX/ERS-1 altimeter data

Digital Repository Service at National Institute of Oceanography (India)

Mohanty, K.K.; Majumdar, T.J.; Kunte, P.D.; Srivastava, A.K.

topography in SSH. Cross-over corrections are applied to account for the orbital error in the altimetric observation. The corrected SSH has been used as an approximation to the marine geoid. The bathymetry is related with the geoid through a convolution model...

Analysis of rocks involving the x-ray diffraction, infrared and thermal gravimetric techniques

International Nuclear Information System (INIS)

Ikram, M.; Rauf, M.A.; Munir, N.

1998-01-01

Chemical analysis of rocks and minerals are usually obtained by a number of analytical techniques. The purpose of present work is to investigate the chemical composition of the rock samples and also to find that how far the results obtained by different instrumental methods are closely related. Chemical tests wee performed before using the instrumental techniques in order to determined the nature of these rocks. The chemical analysis indicated mainly the presence of carbonate and hence the carbonate nature of these rocks. The x-ray diffraction, infrared spectroscopy and thermal gravimetric analysis techniques were used for the determination of chemical composition of these samples. The results obtained by using these techniques have shown a great deal of similarities. (author)

The Analysis of Height System Definition and the High Precision GNSS Replacing Leveling Method

Directory of Open Access Journals (Sweden)

ZHANG Chuanyin

2017-08-01

Full Text Available Based on the definition of height system, the gravitational equipotential property of height datum surface is discussed in this paper, differences of the heights at ground points that defined in different height systems are tested and analyzed as well. A new method for replacing leveling using GNSS is proposed to ensure the consistency between GNSS replacing leveling and spirit leveling at mm accuracy level. The main conclusions include:①For determining normal height at centimeter accuracy level, the datum surface of normal height should be the geoid. The 1985 national height datum of China adopts normal height system, its datum surface is the geoid passing the Qingdao zero point.②The surface of equi-orthometric height in the near earth space is parallel to the geoid. The combination of GNSS precise positioning and geoid model can be directly used for orthometric height determination. However, the normal height system is more advantageous for describing the terrain and relief.③Based on the proposed method of GNSS replacing leveling, the errors in geodetic height affect more on normal height result than the errors of geoid model, the former is about 1.5 times of the latter.

Space-Wise approach for airborne gravity data modelling

Science.gov (United States)

Sampietro, D.; Capponi, M.; Mansi, A. H.; Gatti, A.; Marchetti, P.; Sansò, F.

2017-05-01

Regional gravity field modelling by means of remove-compute-restore procedure is nowadays widely applied in different contexts: it is the most used technique for regional gravimetric geoid determination, and it is also used in exploration geophysics to predict grids of gravity anomalies (Bouguer, free-air, isostatic, etc.), which are useful to understand and map geological structures in a specific region. Considering this last application, due to the required accuracy and resolution, airborne gravity observations are usually adopted. However, due to the relatively high acquisition velocity, presence of atmospheric turbulence, aircraft vibration, instrumental drift, etc., airborne data are usually contaminated by a very high observation error. For this reason, a proper procedure to filter the raw observations in both the low and high frequencies should be applied to recover valuable information. In this work, a software to filter and grid raw airborne observations is presented: the proposed solution consists in a combination of an along-track Wiener filter and a classical Least Squares Collocation technique. Basically, the proposed procedure is an adaptation to airborne gravimetry of the Space-Wise approach, developed by Politecnico di Milano to process data coming from the ESA satellite mission GOCE. Among the main differences with respect to the satellite application of this approach, there is the fact that, while in processing GOCE data the stochastic characteristics of the observation error can be considered a-priori well known, in airborne gravimetry, due to the complex environment in which the observations are acquired, these characteristics are unknown and should be retrieved from the dataset itself. The presented solution is suited for airborne data analysis in order to be able to quickly filter and grid gravity observations in an easy way. Some innovative theoretical aspects focusing in particular on the theoretical covariance modelling are presented too

Estimation of generation and gravimetric composition of solid wastes at Federal University of Campina Grande, Pombal, Paraíba, Brazil

Directory of Open Access Journals (Sweden)

Elisângela Maria da Silva

2018-01-01

Full Text Available The objective was to present the estimation of the per capita generation and gravimetric composition of the solid residues of the Center of Sciences and Agri-food technology of the Federal University of Campina Grande. These two characteristics are of fundamental importance in the solid waste management process. The methodological procedure was carried out by field survey to identify the number of sectors in the University Campus, as well as the quantification of the daily population that attends the institution. As a result, the daily per capita generation of the Science Center and Environmental Technology was 49.28 g. In relation to the gravimetric composition, it was verified that the organic matter had the highest percentage, representing a total of 66%, followed by 13% of plastics, 9% of paper / cardboard and 8% of composites. It is concluded that the largest part of the total solid waste generated is putrescible organic matter, which was already expected, since solid waste generated in the university campus presents characteristics of household waste.

Measurement of Gd content in (U,Gd)O2 using thermal gravimetric analysis

International Nuclear Information System (INIS)

Kim, Keon Sik; Yang, Jae Ho; Kang, Ki Won; Song, Kun Woo; Kim, Gil Moo

2004-01-01

We propose a simple and precise method for measuring the Gd content in the (U,Gd)O 2 pellet by only measuring the weight variation of the pellet during thermal heat treatment in air. The (U,Gd)O 2 fuel pellets were oxidized at 475 deg. C, subsequently heat treated at 1300 deg. C, and then cooled to room temperature in air. The accompanying weight variations were measured using thermo gravimetric analysis (TGA). The measured weight variations were mathematically analyzed with reference to the successive phase reactions during the heat treatment. This method provides an advantage in that the rare-earth element content including Gd can be measured using relatively simple equipment such as an electric furnace and a balance

Gravimetric Viral Diagnostics: QCM Based Biosensors for Early Detection of Viruses

Directory of Open Access Journals (Sweden)

Adeel Afzal

2017-02-01

Full Text Available Viruses are pathogenic microorganisms that can inhabit and replicate in human bodies causing a number of widespread infectious diseases such as influenza, gastroenteritis, hepatitis, meningitis, pneumonia, acquired immune deficiency syndrome (AIDS etc. A majority of these viral diseases are contagious and can spread from infected to healthy human beings. The most important step in the treatment of these contagious diseases and to prevent their unwanted spread is to timely detect the disease-causing viruses. Gravimetric viral diagnostics based on quartz crystal microbalance (QCM transducers and natural or synthetic receptors are miniaturized sensing platforms that can selectively recognize and quantify harmful virus species. Herein, a review of the label-free QCM virus sensors for clinical diagnostics and point of care (POC applications is presented with major emphasis on the nature and performance of different receptors ranging from the natural or synthetic antibodies to selective macromolecular materials such as DNA and aptamers. A performance comparison of different receptors is provided and their limitations are discussed.

Thermal analysis of thermo-gravimetric measurements of spent nuclear fuel oxidation rates

International Nuclear Information System (INIS)

Cramer, E.R.

1997-01-01

A detailed thermal analysis was completed of the sample temperatures in the Thermo-Gravimetric Analysis (TGA) system used to measure irradiated N Reactor fuel oxidation rates. Sample temperatures during the oxidation process did not show the increase which was postulated as a result of the exothermic reactions. The analysis shows the axial conduction of heat in the sample holder effectively removes the added heat and only a very small, i.e., <10 C, increase in temperature is calculated. A room temperature evaporation test with water showed the sample thermocouple sensitivity to be more than adequate to account for a temperature change of approximately 5 C. Therefore, measured temperatures in the TGA are within approximately 10 C of the actual sample temperatures and no adjustments to reported data to account for the heat input from the oxidation process are necessary

Experimental aspects of buoyancy correction in measuring reliable high-pressure excess adsorption isotherms using the gravimetric method

Science.gov (United States)

Nguyen, Huong Giang T.; Horn, Jarod C.; Thommes, Matthias; van Zee, Roger D.; Espinal, Laura

2017-12-01

Addressing reproducibility issues in adsorption measurements is critical to accelerating the path to discovery of new industrial adsorbents and to understanding adsorption processes. A National Institute of Standards and Technology Reference Material, RM 8852 (ammonium ZSM-5 zeolite), and two gravimetric instruments with asymmetric two-beam balances were used to measure high-pressure adsorption isotherms. This work demonstrates how common approaches to buoyancy correction, a key factor in obtaining the mass change due to surface excess gas uptake from the apparent mass change, can impact the adsorption isotherm data. Three different approaches to buoyancy correction were investigated and applied to the subcritical CO2 and supercritical N2 adsorption isotherms at 293 K. It was observed that measuring a collective volume for all balance components for the buoyancy correction (helium method) introduces an inherent bias in temperature partition when there is a temperature gradient (i.e. analysis temperature is not equal to instrument air bath temperature). We demonstrate that a blank subtraction is effective in mitigating the biases associated with temperature partitioning, instrument calibration, and the determined volumes of the balance components. In general, the manual and subtraction methods allow for better treatment of the temperature gradient during buoyancy correction. From the study, best practices specific to asymmetric two-beam balances and more general recommendations for measuring isotherms far from critical temperatures using gravimetric instruments are offered.

Unigrace - A Project For The Unification of Gravity Systems In Central Europe

Science.gov (United States)

Richter, B.; Falk, R.; Erker, E.; Ruess, D.; Mäkinen, J.; Hinderer, J.; Marson, I.; Sledzinski, J.

Because of the present trends of political and economical unification in Europe for- merly classified gravimetric data in Central Europe are becoming available. The dif- ferences, however, between gravity systems in this area are so large that they strongly affect the geoid, vertical datum definitions and height systems. It is therefore manda- tory to study system differences and to unify them. The project UNIGRACE aims at solving this problem by carrying out absolute grav- ity measurements with the most advanced technology at 17 selected sites in the coun- tries concerned. In a joint effort five European groups from Austria, Finland, France, Germany, Italy and Poland using their absolute gravimeters and partners from Bul- garia, Croatia, Czech Republic, Hungary, Romania, Slovakia and Slovenia cooperate in selecting and/or establishing the sites and performing the measurements as well as in connecting the absolute sites to the national gravimetric networks. As a result, a unique gravity system in Central Europe will be available. The project started on Jan. 1, 1998 and till the end of 2000 all selected gravity sites have been observed twice by absolute gravimeters. From these repeated measurements the final results for this project will be presented which was granted by the European Commission.

Impact Of GOCE On The Nordic Gravity Field Modelling

DEFF Research Database (Denmark)

Yidiz, Hasan; Forsberg, René; Tscherning, C. C.

2011-01-01

GOCE level-2 Tzz and Txx gravity gradients at satellite altitude are used in combination as input data to predict surface free air gravity anomalies over the Nordic region using Least Square Collocation. We test the performance of using covariance functions created separately from Tzz gradients a...... Surface model, both the NKG-2004 quasi-geoid model of the Nordic and Baltic Area and the one obtained using second generation GOCE spherical harmonic coefficients based on time-wise method can successfully reproduce the higher level of the Baltic Sea relative to the Atlantic Ocean....

Evaluation of EGM2008 by means of GPS Levelling Uganda | Abeho ...

African Journals Online (AJOL)

For testing the model, a total of seven levelled benchmarks available in Uganda which belong to the New Khartoum datum were used. The spatial positions of these benchmarks were determined at mm accuracy, with respect to ITRF2008. The agreement between the EGM2008 geoid and the geoid undulation derived from ...

Sensors Technology and Advanced Signal Processing Concepts for Layered Warfare/Layered Sensing

Science.gov (United States)

2010-04-01

accurate model of the earth is a geoid defined as the shape of the gravitational equipotential of the earth’s surface . However, geoid models are often...processing framework is inadequate when confronted with complex surface target engagement applications being addressed by layered sensing. The...United States’ combat advantage in surface target engagement. Over the past 20+ years, the US has gathered a large quantity of information on the

Validation of phenol red versus gravimetric method for water reabsorption correction and study of gender differences in Doluisio's absorption technique.

Science.gov (United States)

Tuğcu-Demiröz, Fatmanur; Gonzalez-Alvarez, Isabel; Gonzalez-Alvarez, Marta; Bermejo, Marival

2014-10-01

The aim of the present study was to develop a method for water flux reabsorption measurement in Doluisio's Perfusion Technique based on the use of phenol red as a non-absorbable marker and to validate it by comparison with gravimetric procedure. The compounds selected for the study were metoprolol, atenolol, cimetidine and cefadroxil in order to include low, intermediate and high permeability drugs absorbed by passive diffusion and by carrier mediated mechanism. The intestinal permeabilities (Peff) of the drugs were obtained in male and female Wistar rats and calculated using both methods of water flux correction. The absorption rate coefficients of all the assayed compounds did not show statistically significant differences between male and female rats consequently all the individual values were combined to compare between reabsorption methods. The absorption rate coefficients and permeability values did not show statistically significant differences between the two strategies of concentration correction. The apparent zero order water absorption coefficients were also similar in both correction procedures. In conclusion gravimetric and phenol red method for water reabsorption correction are accurate and interchangeable for permeability estimation in closed loop perfusion method. Copyright © 2014 Elsevier B.V. All rights reserved.

Analytical methods used at model facility

International Nuclear Information System (INIS)

Wing, N.S.

1984-01-01

A description of analytical methods used at the model LEU Fuel Fabrication Facility is presented. The methods include gravimetric uranium analysis, isotopic analysis, fluorimetric analysis, and emission spectroscopy

Li4FeH6: Iron-containing complex hydride with high gravimetric hydrogen density

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Hiroyuki Saitoh

2014-07-01

Full Text Available Li4FeH6, which has the highest gravimetric hydrogen density of iron-containing complex hydrides reported so far, is synthesized by hydrogenation of a powder mixture of iron and LiH above 6.1 GPa at 900 °C. In situ synchrotron radiation X-ray diffraction measurements reveal that while kinetics require high temperature and thus high pressure for the synthesis, Li4FeH6 is expected to be thermodynamically stable slightly below room temperature at ambient pressure; further synthetic studies to suppress the kinetic effects may enable us to synthesize Li4FeH6 at moderate pressures. Li4FeH6 can be recovered at ambient conditions where Li4FeH6 is metastable.

Pathway to 2022: The Ongoing Modernization of the United States National Spatial Reference System

Science.gov (United States)

Stone, W. A.; Caccamise, D.

2017-12-01

The National Oceanic and Atmospheric Administration's National Geodetic Survey (NGS) mission is "to define, maintain and provide access to the National Spatial Reference System (NSRS) to meet our nation's economic, social, and environmental needs." The NSRS is an assemblage of geophysical and geodetic models, tools, and data, with the most-visible components being the North American Datum of 1983 (NAD83) and the North American Vertical Datum of 1988 (NAVD88), which together provide a consistent spatial reference framework for myriad geospatial applications and positioning requirements throughout the United States. The NGS is engaged in an ongoing and comprehensive multi-year project of modernizing the NSRS, a makeover necessitated by technological developments and user accuracy requirements, all with a goal of providing a modern, accurate, accessible, and globally aligned national positioning framework exploiting the substantial power and utility of the Global Navigation Satellite System - of both today and tomorrow. The modernized NSRS will include four new-generation geometric terrestrial reference frames (replacing NAD83) and a technically unprecedented geopotential datum (replacing NAVD88), all to be released in 2022 (anticipated). This poster/presentation will describe the justification for this modernization effort and will update the status and planned evolution of the NSRS as 2022 draws ever closer. Also discussed will be recent developments, including the publication of "blueprint" documents addressing technical details of various facets of the modernized NSRS and a continued series of public Geospatial Summits. Supporting/ancillary projects such as Gravity for the Redefinition of the American Vertical Datum (GRAV-D), which will result in the generation of a highly accurate gravimetric geoid - or definitional reference surface (zero elevation) - for the future geopotential datum, and Geoid Slope Validation Surveys (GSVS), which are exploring the achievable

Seismic, gravimetric and geological interpretation of an Andean transect in Venezuela; Interpretacion sismica, gravimetrica y geologica de un perfil transandino venezolano

Energy Technology Data Exchange (ETDEWEB)

Jacome R, Maria Ines; Audemard, Felipe; Gratero, Victor [Universidad Simon Bolivar, Caracas (Venezuela)

1995-12-31

The combination of seismic, gravimetric and geologic data allowed the construction of a crustal model from the Venezuela Andes. This model is aiming to improve the knowledge from this problematic region. The profile is 160 Km long and it cuts perpendicularly the Andes, across the Soledad, Celoso, Bocono, Virtudes and Gavilan faults. The interpreted reflexions seismic profiles lie both flanks of the Venezuelan Andes. Bouguer anomaly lows do not occurs along the central axis but on the satellite basins located along the Northwestern and Southeastern flanks. The contours tend to group on these flanks reflecting a system related to reverse faults. It was also observed a density contrast separating the Cretaceous-Tertiary from the basement lying at depths greater than 5 Km in the northern Barinas Basin. The same contrast was detected around 10 km along the southern Lake Maracaibo area. The Venezuelan Andes is an asymmetric northern vergent Neogene structure generated under compression, transmitted along basement involved thrusts dipping Southeast. In consequence the tectonic transport is from the Southeast to the Northwest. (author). 7 refs., 5 figs., 2 tabs

Resonant gravimetric immunosensing based on capacitive micromachined ultrasound transducers

KAUST Repository

Viržonis, Darius

2014-04-08

High-frequency (40 MHz) and low-frequency (7 MHz) capacitive micromachined ultrasound transducers (CMUT) were fabricated and tested for use in gravimetric detection of biomolecules. The low-frequency CMUT sensors have a gold-coated surface, while the high-frequency sensors have a silicon nitride surface. Both surfaces were functionalized with bovine leukemia virus antigen gp51 acting as the antigen. On addition of an a specific antibody labeled with horseradish peroxidase (HRP), the antigen/antibody complex is formed on the surface and quantified by HRP-catalyzed oxidation of tetramethylbenzidine. It has been found that a considerably smaller quantity of immuno complex is formed on the high frequency sensor surface. In parallel, the loading of the surface of the CMUT was determined via resonance frequency and electromechanical resistance readings. Following the formation of the immuno complexes, the resonance frequencies of the low-frequency and high-frequency sensors decrease by up to 420 and 440 kHz, respectively. Finite element analysis reveals that the loading of the (gold-coated) low frequency sensors is several times larger than that on high frequency sensors. The formation of the protein film with pronounced elasticity and stress on the gold surface case is discussed. We also discuss the adoption of this method for the detection of DNA using a hybridization assay following polymerase chain reaction.

Geopotential Stress

DEFF Research Database (Denmark)

Schiffer, Christian; Nielsen, S.B.

Density heterogeneity in the Earth’s lithosphere causes lateral pressure variations. Horizontal gradients of the vertically integrated lithostatic pressure, the Geopotential Energy (GPE), are a source of stresses (Geopotential Stress) that contribute to the Earth’s Stress Field. In theory the GPE...... is linearly related to the lithospheric part of the Geoid. The Geopotential Stress can be calculated if either the density structure and as a consequence the GPE or the lithospheric contribution to the Geoid is known. The lithospheric Geoid is usually obtained by short pass filtering of satellite Geoid...... are not entirely suitable for the stress calculations but can be compiled and adjusted. We present an approach in which a global lithospheric density model based on CRUST2.0 is obtained by simultaneously fitting topography and surface heat flow in the presence of isostatic compensation and long-wavelength lateral...

A comparison of daily water use estimates derived from constant-heat sap-flow probe values and gravimetric measurements in pot-grown saplings.

Science.gov (United States)

K.A. McCulloh; K. Winter; F.C. Meinzer; M. Garcia; J. Aranda; Lachenbruch B.

2007-01-01

The use of Granier-style heat dissipation sensors to measure sap flow is common in plant physiology, ecology, and hydrology. There has been concern that any change to the original Granier design invalidates the empirical relationship between sap flux density and the temperature difference between the probes. We compared daily water use estimates from gravimetric...

Digital terrain model evaluation and computation of the terrain correction and indirect effect in South America

Directory of Open Access Journals (Sweden)

Denizar Blitzkow

2009-12-01

Full Text Available The main objectives of this paper are to compare digital terrain models, to show the generated models for South America and to present two applications. Shuttle Radar Topography Mission (SRTM produced the most important and updated height information in the world. This paper addresses the attention to comparisons of the following models: SRTM3, DTM2002, GLOBE, GTOPO30, ETOPO2 and ETOPO5, at the common points of the grid. The comparisons are limited by latitudes 60º S and 25 º N and longitudes 100 º W and 25 º W. All these data, after some analysis, have been used to create three models for South America: SAM_1mv1, SAM_1mv2 (both of 1' grid spacing and SAM_30s (30" grid spacing. Besides this effort, the three models as well as STRM were evaluated using Bench Marks (BM in Brazil and Argentina. This paper also shows two important geodesy and geophysics applications using the SAM_1mv1: terrain correction (one of the reductions applied to the gravity acceleration and indirect effect (a consequence of the reduction of the external mass to the geoid. These are important at Andes for a precise geoid computation.Los objetivos principales de este documento son comparar modelos digitales del continente; enseñar los modelos generados para Sudamérica y presentar dos aplicaciones. Shuttle Radar Topography Mission (SRTM produjo la información más importante y más actualizada de las altitudes del mundo. Este trabajo centra su atención en las comparaciones de los modelos siguientes: SRTM3, DTM2002, GLOBO, GTOPO30, ETOPO2 y ETOPO5, en los puntos comunes de la rejilla. Las comparaciones son limitadas por las latitudes 60º S y 25 º N y longitudes 100 º W y 25 º W. Todos estos datos, después de los análisis, se han utilizado para crear tres modelos para Sudamérica: SAM_1mv1, SAM_1mv2 (1' de espaciamiento de la rejilla y SAM_30s (30" de espaciamiento de la rejilla. Los tres modelos bien como el STRM fueron evaluados usando puntos de referencia de

Determination of oxygen to metal ratio for varying UO2 content in sintered (U,Th)O2 pellet by oxidation-reduction method using thermo-gravimetric analyser

International Nuclear Information System (INIS)

Mahanty, B.N.; Khan, F.A.; Karande, A.P.; Prakash, A.; Afzal, Md.; Panakkal, J.P.

2009-01-01

Experiments were carried out to determine oxygen to metal ratio in 4%, 6%, 10%, 20%, 50% and 80% UO 2 in sintered (U, Th) O 2 pellets by oxidation-reduction method using thermo gravimetric analyser. (author)

3-D lithospheric structure and regional/residual Bouguer anomalies in the Arabia-Eurasia collision (Iran)

Science.gov (United States)

Jiménez-Munt, I.; Fernãndez, M.; Saura, E.; Vergés, J.; Garcia-Castellanos, D.

2012-09-01

The aim of this work is to propose a first-order estimate of the crustal and lithospheric mantle geometry of the Arabia-Eurasia collision zone and to separate the measured Bouguer anomaly into its regional and local components. The crustal and lithospheric mantle structure is calculated from the geoid height and elevation data combined with thermal analysis. Our results show that Moho depth varies from ˜42 km at the Mesopotamian-Persian Gulf foreland basin to ˜60 km below the High Zagros. The lithosphere is thicker beneath the foreland basin (˜200 km) and thinner underneath the High Zagros and Central Iran (˜140 km). Most of this lithospheric mantle thinning is accommodated under the Zagros mountain belt coinciding with the suture between two different mantle domains on the Sanandaj-Sirjan Zone. The regional gravity field is obtained by calculating the gravimetric response of the 3-D crustal and lithospheric mantle structure obtained by combining elevation and geoid data. The calculated regional Bouguer anomaly differs noticeably from those obtained by filtering or just isostatic methods. The residual gravity anomaly, obtained by subtraction of the regional components to the measured field, is analyzed in terms of the dominating upper crustal structures. Deep basins and areas with salt deposits are characterized by negative values (˜-20 mGal), whereas the positive values are related to igneous and ophiolite complexes and shallow basement depths (˜20 mGal).

Composição gravimétrica de resíduos sólidos aterrados Gravimetric composition of solid waste landfill

Directory of Open Access Journals (Sweden)

Greice Mattei

2007-09-01

Full Text Available A composição gravimétrica de um aterro de resíduos sólidos (RS é uma informação básica para o monitoramento e avaliação de projetos ambientais. A obtenção dessa informação é dificultada pela inexistência de procedimentos padrões de amostragem, pela heterogeneidade dos RS e pela forma de disposição desses resíduos ou tipo de aterro, entre outros fatores. Esse trabalho teve como objetivo determinar se há diferença entre a composição gravimétrica de materiais aterrados em um lixão e em um aterro controlado, além de avaliar se essa composição varia com a profundidade de amostragem. Constatou-se pouca diferença na composição gravimétrica dos RS entre os aterros. No aterro controlado predominou a massa pastosa (41,2 %, enquanto que no lixão houve maior teor de plástico filme (35,0 %. A composição dos resíduos aterrados não variou com a profundidade de amostragem.The gravimetric composition of solid waste (SW landfill is basic information for environmental monitoring and projects evaluation. The lack of standard procedures for sampling, the inherent heterogeneity of SW and the different disposal techniques of such wastes or type of landfill, among other factors, have imposed certain limitations to obtain data about landfill gravimetric composition. The objective of this work was to evaluate the difference between the gravimetric composition of SW collected from an open dump and from a controlled landfill and to evaluate if this composition changes with depth of sampling. There was little difference between the SW collected in the two types of landfills. In the controlled landfill pasted mass (41,2 % was the major component, while in the open dump the plastic film (35,0 % was the most common material. The SW composition did not change with the sampling depth.

Determination of total dietary fiber (CODEX definition) by enzymatic-gravimetric method and liquid chromatography: collaborative study.

Science.gov (United States)

McCleary, Barry V; DeVries, Jonathan W; Rader, Jeanne I; Cohen, Gerald; Prosky, Leon; Mugford, David C; Champ, Martine; Okuma, Kazuhiro

2010-01-01

A method for the determination of total dietary fiber (TDF), as defined by the CODEX Alimentarius, was validated in foods. Based upon the principles of AOAC Official Methods 985.29, 991.43, 2001.03, and 2002.02, the method quantitates high- and low-molecular-weight dietary fiber (HMWDF and LMWDF, respectively). In 2007, McCleary described a method of extended enzymatic digestion at 37 degrees C to simulate human intestinal digestion followed by gravimetric isolation and quantitation of HMWDF and the use of LC to quantitate low-molecular-weight soluble dietary fiber (LMWSDF). The method thus quantitates the complete range of dietary fiber components from resistant starch (by utilizing the digestion conditions of AOAC Method 2002.02) to digestion resistant oligosaccharides (by incorporating the deionization and LC procedures of AOAC Method 2001.03). The method was evaluated through an AOAC collaborative study. Eighteen laboratories participated with 16 laboratories returning valid assay data for 16 test portions (eight blind duplicates) consisting of samples with a range of traditional dietary fiber, resistant starch, and nondigestible oligosaccharides. The dietary fiber content of the eight test pairs ranged from 11.57 to 47.83%. Digestion of samples under the conditions of AOAC Method 2002.02 followed by the isolation and gravimetric procedures of AOAC Methods 985.29 and 991.43 results in quantitation of HMWDF. The filtrate from the quantitation of HMWDF is concentrated, deionized, concentrated again, and analyzed by LC to determine the LMWSDF, i.e., all nondigestible oligosaccharides of degree of polymerization > or =3. TDF is calculated as the sum of HMWDF and LMWSDF. Repeatability standard deviations (Sr) ranged from 0.41 to 1.43, and reproducibility standard deviations (S(R)) ranged from 1.18 to 5.44. These results are comparable to other official dietary fiber methods, and the method is recommended for adoption as Official First Action.

Comparison of gas chromatographic and gravimetric methods for quantization of total fat and fatty acids in foodstuffs

Directory of Open Access Journals (Sweden)

Sabria Aued-Pimentel

2010-01-01

Full Text Available Different methods to determine total fat (TF and fatty acids (FA, including trans fatty acids (TFA, in diverse foodstuffs were evaluated, incorporating gravimetric methods and gas chromatography with flame ionization detector (GC/FID, in accordance with a modified AOAC 996.06 method. Concentrations of TF and FA obtained through these different procedures diverged (p< 0.05 and TFA concentrations varied beyond 20 % of the reference values. The modified AOAC 996.06 method satisfied both accuracy and precision, was fast and employed small amounts of low toxicity solvents. Therefore, the results showed that this methodology is viable to be adopted in Brazil for nutritional labeling purposes.

Dynamic study of adsorbers by a new gravimetric version of the Large Temperature Jump method

International Nuclear Information System (INIS)

Sapienza, Alessio; Santamaria, Salvatore; Frazzica, Andrea; Freni, Angelo; Aristov, Yuri I.

2014-01-01

Highlights: • We have carried out a dynamic study of adsorbers. • Activity performed by new gravimetric version of the Large Temperature Jump method. • The kinetics measurements have been carried out under real operating conditions. • Results can support the design of adsorbers for adsorption cooling systems. - Abstract: This paper presents a new experimental setup devoted to measure the ad-/desorption kinetics of an Ad-HEX (adsorbent + heat exchanger) under typical boundary conditions of an Adsorption Heat Transformer (AHT) as well as the results of the first test campaign carried out. The experimental apparatus can be considered as a gravimetric version of the known Large Temperature Jump method. In fact, the dynamic evolution of the uptake during the isobaric ad-/desorption stages is directly measured by a weighing system suitable to work in the range of 5–600 g of sample mass (adsorbent + HEX) with the accuracy ±0.1 g and the time response shorter than 0.1 s The experimental campaign was conducted on an Ad-HEX composed of granules of a commercial SAPO-34 adsorbent placed on a flat type aluminum HEX, under operating conditions reproducing two different thermodynamic cycles (T h = 90 °C, T e = 10 °C, T c = 30 and 35 °C), typical for adsorption air conditioning. The influence of the grain size (ranging from 0.350 to 2.5 mm) on the adsorption dynamics both in monolayer and multilayer configurations at variable and constant “heat transfer surface/adsorbent mass” ratios (S/m) was studied. The results showed that, for the Ad-HEX configurations tested, the adsorption dynamics can be properly described by a modified Linear Driving Force approach by the use of a single temperature-invariant characteristic time τ. The invariance of the specific cooling power was revealed when the S/m ratio was kept constant (S/m = 1.23 m 2 /kg). This ratio is found to be a useful parameter for both assessment of the dynamic perfection and optimization of various Ad

A reexamination of the spreading center hypothesis for Ovda and Thetis Regiones, Venus

International Nuclear Information System (INIS)

Kiefer, W.S.

1990-01-01

Ceumpler, Head, and colleagues proposed that Ovda and Thetis Regiones are spreading centers. The strong positive correlation between geoid and topography observed in Ovda and Thetis is unlike that observed for terrestrial spreading centers. The maximum elevation expected for spreading centers on Venus is 1.5 km, and a cooling plate thermal model predicts a maximum geoid anomaly of 8 meters, both much less than observed. Even if a spreading center is operative in Ovda and Thetis, most of the geoid and topography must be due to other mechanisms. Crumpler et al. also proposed the existence of cross-strike discontinuities, interpreted as transform fault zones, but the evidence for these structures is not conclusive

Garnet Signatures in Geophysical and Geochemical Observations: Insights into the Thermo-Petrological Structure of Oceanic Upper Mantle

Science.gov (United States)

Grose, C. J.; Afonso, J. C.

2013-12-01

We have developed new physically comprehensive thermal plate models of the oceanic lithosphere which incorporate temperature- and pressure-dependent heat transport properties and thermal expansivity, melting beneath ridges, hydrothermal circulation near ridge axes, and insulating oceanic crust. These models provide good fits to global databases of seafloor topography and heat flow, and seismic evidence of thermal structure near ridge axes. We couple these thermal plate models with thermodynamic models to predict the petrology of oceanic lithosphere. Geoid height predictions from our models suggest that there is a strong anomaly in geoid slope (over age) above ~25 Ma lithosphere due to the topography of garnet-field mantle. A similar anomaly is also present in geoid data over fracture zones. In addition, we show that a new assessment of a large database of ocean island basalt Sm/Yb systematics indicates that there is an unmistakable step-like increase in Sm/Yb values around 15-20 Ma, indicating the presence of garnet. To explain this feature, we have attempted to couple our thermo-petrological models of oceanic upper mantle with an open system, non-modal, dynamic melting model with diffusion kinetics to investigate trace element partitioning in an ascending mantle column.

Mantle plumes on Venus revisited

Science.gov (United States)

Kiefer, Walter S.

1992-01-01

The Equatorial Highlands of Venus consist of a series of quasicircular regions of high topography, rising up to about 5 km above the mean planetary radius. These highlands are strongly correlated with positive geoid anomalies, with a peak amplitude of 120 m at Atla Regio. Shield volcanism is observed at Beta, Eistla, Bell, and Atla Regiones and in the Hathor Mons-Innini Mons-Ushas Mons region of the southern hemisphere. Volcanos have also been mapped in Phoebe Regio and flood volcanism is observed in Ovda and Thetis Regiones. Extensional tectonism is also observed in Ovda and Thetis Regiones. Extensional tectonism is also observed in many of these regions. It is now widely accepted that at least Beta, Atla, Eistla, and Bell Regiones are the surface expressions of hot, rising mantel plumes. Upwelling plumes are consistent with both the volcanism and the extensional tectonism observed in these regions. The geoid anomalies and topography of these four regions show considerable variation. Peak geoid anomalies exceed 90 m at Beta and Atla, but are only 40 m at Eistla and 24 m at Bell. Similarly, the peak topography is greater at Beta and Atla than at Eistla and Bell. Such a range of values is not surprising because terrestrial hotspot swells also have a side range of geoid anomalies and topographic uplifts. Kiefer and Hager used cylindrical axisymmetric, steady-state convection calculations to show that mantle plumes can quantitatively account for both the amplitude and the shape of the long-wavelength geoid and topography at Beta and Atla. In these models, most of the topography of these highlands is due to uplift by the vertical normal stress associated with the rising plume. Additional topography may also be present due to crustal thickening by volcanism and crustal thinning by rifting. Smrekar and Phillips have also considered the geoid and topography of plumes on Venus, but they restricted themselves to considering only the geoid-topography ratio and did not

Gravimetric quantitative determination of packaging residues in feed from former food.

Science.gov (United States)

Amato, Giuseppina; Desiato, Rosanna; Giovannini, Tiziana; Pinotti, Luciano; Tretola, Marco; Gili, Marilena; Marchis, Daniela

2017-08-01

Valorisation of former foodstuff products (FFP) in feed is part of a long-term strategy for sustainability. An approach to valorise FFP outside the waste value chain is their use as an alternative source of feed materials, with a subsequent optimisation of the environmental impact of products. In the current practice of food production, food packaging is provided to ensure the maintenance of food quality and safety during transport and storage. One of the problems of reusing FFP is how to deal with packaging materials or remains that can become residues in the feed. The aim of this study is to propose a fast and sensitive gravimetric method, fit for routine official controls, for the determination of packaging residues in feed. The developed method can briefly be summarised as: (1) visual selection of the undesired ingredients which can be identified as remnants of packaging materials; (2) weighing of the selected materials; (3) defatting; (4) dehydration; (5) final weighing; and (6) reporting of weight and percentage. Moreover, the method has been validated through the determination of some of the parameters listed in Council Regulation 2004/882/EC (i.e., specificity, limit of quantification (LOQ), recovery, repeatability, within-laboratory reproducibility and measurement uncertainty).

Mass change distribution inverted from space-borne gravimetric data using a Monte Carlo method

Science.gov (United States)

Zhou, X.; Sun, X.; Wu, Y.; Sun, W.

2017-12-01

Mass estimate plays a key role in using temporally satellite gravimetric data to quantify the terrestrial water storage change. GRACE (Gravity Recovery and Climate Experiment) only observes the low degree gravity field changes, which can be used to estimate the total surface density or equivalent water height (EWH) variation, with a limited spatial resolution of 300 km. There are several methods to estimate the mass variation in an arbitrary region, such as averaging kernel, forward modelling and mass concentration (mascon). Mascon method can isolate the local mass from the gravity change at a large scale through solving the observation equation (objective function) which represents the relationship between unknown masses and the measurements. To avoid the unreasonable local mass inverted from smoothed gravity change map, regularization has to be used in the inversion. We herein give a Markov chain Monte Carlo (MCMC) method to objectively determine the regularization parameter for the non-negative mass inversion problem. We first apply this approach to the mass inversion from synthetic data. Result show MCMC can effectively reproduce the local mass variation taking GRACE measurement error into consideration. We then use MCMC to estimate the ground water change rate of North China Plain from GRACE gravity change rate from 2003 to 2014 under a supposition of the continuous ground water loss in this region. Inversion result show that the ground water loss rate in North China Plain is 7.6±0.2Gt/yr during past 12 years which is coincident with that from previous researches.

Creating Orthographically Rectified Satellite Multi-Spectral Imagery with High Resolution Digital Elevation Model from LiDAR: A Tutorial

Science.gov (United States)

2014-08-15

EGM96 refers to the equipotential gravity field depicting mean-sea-level across the Earth that is commonly called the geoid...raster and commercial satellite MSI data that are combined in the process of making orthoimages, where feature extraction for models of surface material...peaks along the waveform that show a strong returned laser signal reflected from a rela- tively solid terrain surface or subsurface for the entire

Characterization of the structure of the Salar de Atacama Basin through gravimetric profiles and interval velocity analysis.

Science.gov (United States)

Becerra, J.; Bascunan, S. A.; Maksymowicz, A.; Martínez, F.; Arriagada, C.

2017-12-01

The structure of the basins found in the Preandean Depression in the northern Central Andes has remained elusive, partly due to a poor understanding of the structural styles and stratigraphy beneath their surface. An independent approach to the multiple interpretations of seismic lines available is the analysis of 2D gravity profiles. An E-W profile was performed across the basin, closely matching the surficial trace of previous seismic lines. The profile shows three gravimetric lows, the most relevant being one beneath the Llano de la Paciencia- Cordillera de la Sal, comprised of deformed evaporitic and terrigenous deposits of Oligocene-Early Miocene age. The structure which bounds this gravity low has a steeper dip on its eastern side, bounding the eastern side of the Cordillera de la Sal, which is at odds with previous studies that interpreted its western contact with Cretaceous outcrops as the possible basin boundary. The 3-D analyses of seismic interval velocity data around the gravimetric survey reveal a major vertical contrast in the eastern portion of the profile, interpreted as the bottom of the evaporite successions, followed to the west by a complex, narrow and deep zone of low velocities. Westward, the Cretaceous rocks record higher velocities than its post-Paleocene counterparts, and an almost uniform increase in velocity with depth. The major gravity anomaly is closely related to the Cordillera de la Sal, which consists of an array of folds and reverse faults involving Oligocene to recent deposits. We propose that the faults which generated Oligocene extension are not at the western border of the basin, but around the Cordillera de la Sal, which is the result of Miocene inversion of the same system. Strike-slip deformation was also probably a major contributor in basin formation, as shown by the narrow yet deep shape of the depocenter.

Determinations of total residue, total oxide and density of high-level liquid waste (HLLW) by gravimetric method

International Nuclear Information System (INIS)

Li Yun; Gao Yueying; Yang Ming; Jin Liyun

1992-01-01

Gravimetric method for determination of total residue, total oxide and density of HLLW is developed. An aliquot of the original HLLW solution is piped on to the small quartz disc and put into the mini muffle furnace carefully. It is first heated to below 100 degree C (for 1.5 hours to remove the free water, and then heated to 180 degree C for 2 hours to remove the crystal water in a furnace. The total residue is weighed at room temperature. The precision is better than 3% for the determination of total residue and total oxide. An aliquot of the original HLLW solution is piped into the weighing bottle and weighed. The precision is better than 1%

Tannins gravimetric yield condensed in Anadenanthera peregrina bark in different diameter classes

Directory of Open Access Journals (Sweden)

Caroline Junqueira Sartori

2014-06-01

Full Text Available This work aimed to determine the gravimetric yield of condensed tannins in the Anadenanthera peregrina bark in different diameter classes. Fifty-nine trees samples were collected of Anadenanthera peregrina, at 1.30m of the ground (diameter at breast height - DBH, distributed in seven diameter classes. The barks were dried and crushed in mill of hammer. Composite sample was made to prepare the extract. The extraction was done using water in the ratio 15:1 (v/w, added 3% sodium sulfite (w/w in water-bath at 70°C for 4 hours. The material was filtered using fine cloth strainer and concentrated on a heating plate at approximately 150 g. It was determined the extract mass and removed 10 g for obtaining solids content and 20g for the Stiasny's index. The average values of total solids content, Stiasny's index, condensed tannin content and the compound content non-tannin were 11.34%; 75.79%; 12.76% and 4.07%, respectively. The content of solids, Stiasny's index, compound content non-tannin show significant differences between diameter classes. For the condensed tannins production, the diameter class parameter there was no influence.

The geothermal gradient map of Central Tunisia: Comparison with structural, gravimetric and petroleum data

Science.gov (United States)

Dhia, Hamed Ben

1987-10-01

Five hundred and fifty temperature values, initially measured as either bottom-hole temperatures (BHT) or drill-stem tests (DST), from 98 selected petroleum exploration wells form the basis of a geothermal gradient map of central Tunisia. A "global-statistical" method was employed to correct the BHT measurements, using the DST as references. The geothermal gradient ranges from 23° to 49°C/km. Comparison of the geothermal gradient with structural, gravimetric and petroleum data indicates that: (1) the general trend of the geothermal gradient curves reflects the main structural directions of the region, (2) zones of low and high geothermal gradient are correlated with zones of negative and positive Bouguer anomalies and (3) the five most important oil fields of central Tunisia are located near the geothermal gradient curve of 40° C/km. Such associations could have practical importance in petroleum exploration, but their significance must first be established through further investigation and additional data.

Evaluation of the Military Utility of Employing an Angle of Arrival Payload Hosted on a CubeSat as an Augmentation to Existing Geolocation Systems

Science.gov (United States)

2015-03-26

Model 1996 (EGM 96) geoid. The EGM 96 geoid is defined as “the equipotential surface of the Earth’s gravity field which best fits MSL if the sea were...operationally representative scenarios. This research also introduces a high fidelity surface of the earth constraint based upon a digital elevation...distance using a Kalman filter fusion technique. The addition of the surface of earth constraint alone, without fusing multiple estimates, resulted in a 38

Geophysical modeling of Valle de Banderas graben and its structural relation to Bahia de Banderas, Mexico

OpenAIRE

Arzate, Jorge A.; Álvarez, Román; Yutsis, Vsevolod; Pacheco, Jesús; López-Loera, Héctor

2006-01-01

A gravimetric survey consisting of five lines and 483 stations, as well as a magnetotelluric (MT) survey consisting ofl 7 observation sites, were made in the Valle de Banderas region for the determination of the structural characteristics of the valley. Additionally, data from a previous aeromagnetic survey were analyzed to correlate them with our geophysical measurements. The gravimetric and MT models confirm that the valley corresponds to a graben structure with slumped blocks that vary fro...

The International Gravity Field Service (IGFS): Present Day Activities And Future Plans

Science.gov (United States)

Barzaghi, R.; Vergos, G. S.

2016-12-01

IGFS is a unified "umbrella" IAG service that coordinates the servicing of the geodetic and geophysical community with gravity field related data, software and information. The combined data of the IGFS entities will include global geopotential models, terrestrial, airborne, satellite and marine gravity observations, Earth tide data, GPS/levelling data, digital models of terrain and bathymetry, as well as ocean gravity field and geoid from satellite altimetry. The IGFS structure is based on the Gravity Services, the "operating arms" of IGFS. These Services related to IGFS are: BGI (Bureau Gravimetrique International), Toulouse, France ISG (International Service for the Geoid), Politecnico di Milano, Milano, Italy IGETS (International Geodynamics and Earth Tides Service), EOST, Strasbourg, France ICGEM (International Center for Global Earth Models), GFZ, Potsdam, Germany IDEMS (International Digital Elevation Model Service), ESRI, Redlands, CA, USA The Central Bureau, hosted at the Aristotle Thessaloniki University, is in charge for all the interactions among the services and the other IAG bodies, particularly GGOS. In this respect, connections with the GGOS Bureaus of Products and Standards and of Networks and Observations have been recently strengthened in order to align the Gravity services to the GGOS standards. IGFS is also strongly involved in the most relevant projects related to the gravity field such as the establishment of the new Global Absolute Gravity Reference System and of the International Height Reference System. These projects, along with the organization of Geoid Schools devoted to methods for gravity and geoid estimate, will play a central role in the IGFS future actions in the framework of GGOS.

Geodetic parametrisation of the CNGS project

International Nuclear Information System (INIS)

Jones, Mark; Mayoud, Michel; Wiart, Aude

2003-01-01

The CNGS (CERN Neutrinos to Gran Sasso) project aims to investigate the oscillation' of neutrinos. A beam extracted from the CERN SPS accelerator will produce a beam consisting uniquely of muon-type neutrinos that will be directed underground to their destination, the Gran Sasso National Laboratory (LNGS) in Italy, 730 km from CERN. For the CNGS project it is evident that our knowledge of the relative position of the two Laboratories, indeed the relative position of the neutrino target at CERN and the detector at Gran Sasso, is essential. Up until the CNGS Project the position of the CERN accelerators on a global scale has not been critical. Two GPS campaigns carried out in 1998, have now resolved this question to a high degree of accuracy, and a GPS survey campaign at Gran Sasso has provided us with the relative position. The parameters for the civil engineering work that started in September 2000 are all based upon the information from these two GPS campaigns. However, consultation with the national surveying bodies in France (IGN) and Switzerland (OFT) showed that the geoid model used for the LEP would probably need to be updated for the alignment of the CNGS accelerator components. Based upon the 1998 Swiss geoid model (CHGEO98) a new model of the geoid and technique for its exploitation has been implemented at CERN (CG2000). The parameters establishing the position of the CERN Laboratory together with those of the CNGS beam line have now been refined again. This new geoid model is currently being incorporated into our various algorithms. (author)

Unraveling African plate structure from elevation, geoid and geology data: implications for the impact of mantle flow and sediment transfers on lithospheric deformation

Science.gov (United States)

Bajolet, Flora; Robert, Alexandra; Chardon, Dominique; Rouby, Delphine

2017-04-01

The aim of our project is to simulate the long-wavelength, flexural isostatic response of the African plate to sediment transfers due to Meso-Cenozoic erosion - deposition processes in order to extract the residual topography driven by mantle dynamics. The first step of our project consists in computing crustal and lithospheric thickness maps of the African plate considering its main geological components (cratons, mobile belts, basins, rifts and passive margins of various ages and strengths). In order to consider these heterogeneities, we compute a 2D distribution of crustal densities and thermal parameters from geological data and use it as an input of our modeling. We combine elevation and geoid anomaly data using a thermal analysis, following the method of Fullea et al. (2007) in order to map crustal and lithospheric thicknesses. In this approach, we assume local isostasy and consider a four-layer model made of crust and lithospheric mantle plus seawater and asthenosphere. In addition, we compare our results with crustal and lithospheric thickness datasets compiled from bibliography and existing global models. The obtained crustal thicknesses range from 28 to 42km, with the thickest crust confined to the northern part of the West African Craton, the Kaapvaal craton, and the Congo cuvette. The crust in the East African Rift appears unrealistically thick (40-45 km) as it is not isotatically compensated, highlighting the dynamic effect of the African superswell. The thinnest crust (28-34km) follows a central East-West trend coinciding with Cretaceous rifts and the Cameroon volcanic line. The lithosphere reaches 220 km beneath the Congo craton, but remains globally thin (ca. 120-180 km) compared to tomographic models and considering the age of most geological provinces. As for the crust, the thinnest lithosphere is located in areas of Cretaceous-Jurassic rifting, suggesting that the lithosphere did not thermally recover from Mesozoic rifting. A new elastic

Two-dimensional MoS2-graphene hybrid nanosheets for high gravimetric and volumetric lithium storage

Science.gov (United States)

Deng, Yakai; Ding, Lixin; Liu, Qixing; Zhan, Liang; Wang, Yanli; Yang, Shubin

2018-04-01

Two-dimensional (2D) MoS2-graphene (MoS2-G) hybrid is fabricated simultaneously and scalablely with an efficient electrochemical exfoliation approach from the combined bulk MoS2-graphite wafer. The as-prepared 2D MoS2-G hybrid is tightly covered with each other with lateral sizes of 600 nm to few micrometers and can be directly assembled to flexible films for lithium storage. When used as anode material for lithium ion battery, the resultant MoS2-G hybrid film exhibits both high gravimetric (750 mA h g-1 at 50 mA g-1) and volumetric capacities (1200 mA h cm-3 at 0.1 mA cm-2). Such excellent electrochemical performance should attributed to the unique 2D structure and good conductive graphene network, which not only facilitates the diffusion of lithium ions, but also improves the fast transfer of electrons, satisfying the kinetics requirements for rapid lithium storage.

Significant enhancement in volumetric and gravimetric capacitance of Cu-TiO2/PPY composite for supercapacitor application

Science.gov (United States)

Purty, B.; Choudhary, R. B.

2018-04-01

Copper doped titanium dioxide-polypyrrole (Cu-TiO2/PPY) composite was successfully synthesized via chemical oxidative in-situ polymerization process. The structural and morphological properties of Cu-TiO2/PPY composite were investigated using X-ray diffractometer (XRD), field emission electron microscopy (FESEM) and transmission electron microscopy(TEM) techniques. The electrochemical properties of as-synthesized composite were studied using cyclic voltammetry (CV), galvanostatic charge discharge (GCD) and electrochemical impedance spectroscopic (EIS) techniques. The novel Cu-TiO2/PPY composite showed enhanced volumetric capacitance ˜714 F cm-1 and gravimetric capacitance ˜674 F g-1 at 1 A g-1. In addition an excellent coulombic efficiency and comparabley low charge transfer resistance than pure PPY suggests improved supercapacitive performance of Cu-TiO2/PPY composite as an electrode material.

Application of gamma-ray radiography and gravimetric measurements after accelerated corrosion tests of steel embedded in mortar

Energy Technology Data Exchange (ETDEWEB)

Duffó, Gustavo, E-mail: duffo@cnea.gov.ar [Comisión Nacional de Energía Atómica, Gerencia Materiales, Depto. Corrosión, Av. Gral. Paz 1499, 1650 San Martín, Buenos Aires (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Av. Rivadavia 1917, 1033 Buenos Aires (Argentina); Universidad Nacional de San Martín, Av. Gral. Paz 1499, 1650 San Martín, Buenos Aires (Argentina); Gaillard, Natalia [Universidad Nacional de San Martín, Av. Gral. Paz 1499, 1650 San Martín, Buenos Aires (Argentina); Mariscotti, Mario; Ruffolo, Marcelo [Tomografía de Hormigón Armado S.A. (THASA), Reclus 2017, 1609 Boulogne, Buenos Aires (Argentina)

2015-08-15

The accelerated corrosion by the impressed current technique is widely used in studies of concrete durability since it has the advantage that tests can be carried out within reasonable periods of time. In the present work the relationship between the applied current density and the resulting damage on the reinforcing steel, by applying optical microscopy, scanning electron microscopy, gamma-ray radiography and gravimetric measurements, was studied by means of the implementation of accelerated corrosion tests on reinforced mortar. The results show that the efficiency of the applied current is between 1 and 77%, regardless of the applied current density, the water/cement ratio and the mortar cover depth of the specimens. The results show the applicability of the gamma-ray radiography technique to detect localized corrosion of steel rebars in laboratory specimens.

Modelling anisotropic water transport in polymer composite

Indian Academy of Sciences (India)

This work reports anisotropic water transport in a polymer composite consisting of an epoxy matrix reinforced with aligned triangular bars made of vinyl ester. By gravimetric experiments, water diffusion in resin and polymer composites were characterized. Parameters for Fickian diffusion and polymer relaxation models were ...

Assessing performance of gravity models in the Arctic and the implications for polar oceanography

Science.gov (United States)

Thomas, S. F.; McAdoo, D. C.; Farrell, S. L.; Brozena, J. M.; Childers, V. A.; Ziebart, M. K.; Shepherd, A.

2014-12-01

The circulation of the Arctic Ocean is of great interest to both the oceanographic and cryospheric communities. Understanding both the steady state and variations of this circulation is essential to building our knowledge of Arctic climate. With the advent of high inclination altimeter missions such as CryoSat and ICESat, it is now feasible to produce Mean Dynamic Topography (MDT) products for the region, which allow a comprehensive investigation of geostrophic currents. However, the accuracy of these products is largely limited by our knowledge of the marine geoid in the Arctic. There are a number of publicly available gravity models commonly used to derive the geoid. These use different combinations of available data (satellite gravimetry, altimetry, laser ranging, and in-situ) and are calculated using different mathematical techniques. However, the effect of these differences on the real world performance of these models when used for oceanographic studies in the Arctic is not well known. Given the unique problems for gravimetry in the region (especially data gaps) and their potential impact on MDT products, it is especially important that the relative performance of these models be assessed We consider the needs of the "end user" satellite oceanographer in the Arctic with respect to gravimetry, and the relationship between the precision of gravity data and the accuracy of a final MDT/current velocity product. Using high-precision aerogravity data collected over 3 years of campaigns by NASA's Operation IceBridge we inter-compare 10 of the leading gravity models and assess their performance in the Arctic. We also use historical data from campaigns flown by the US Naval Research Laboratory (NRL) to demonstrate the impact of gravity errors on MDT products. We describe how gravity models for the region might be improved in the future, in an effort to maximize the level at which Arctic currents may be resolved.

Towards unification of terrestrial gravity data sets in Estonia

Directory of Open Access Journals (Sweden)

Ellmann, Artu

2009-12-01

Full Text Available Gravity data in Estonia have been collected by different institutions over many decades. This study assesses the suitability of available gravity data for ensuring a 1 cm geoid modelling accuracy over Estonia and in the Baltic Sea region in general. The main focus of this study is on the determination and elimination of discrepancies between three nationwide datasets. It was detected that one tested historic gravity dataset contained inadmissible systematic biases with respect to other tested datasets. Possible ways of gravity data improvement are discussed. More specifically, new field observation campaigns and aspects of using their outcomes in subsequent regional geoid modelling are suggested.

Anestesi Infus Gravimetrik Ketamin dan Propofol pada Anjing (THE GRAVIMETRIC INFUSION ANAESTHESIA WITH KETAMINE AND PROPOFOL IN DOGS

Directory of Open Access Journals (Sweden)

I Gusti Ngurah Sudisma

2014-08-01

Full Text Available This study aim was to evaluate quality of anaesthesia by using gravimetric infusion anaesthesia withketamine and propofol in dogs. The quality of anaesthesia, duration of actions, and the physiological responsseof anaesthesia were evaluated in twenty domestic dogs. Anaesthesia was induced intramuscularly withatropine (0.03 mg/kg-xylazine (2 mg/kg (AX, intravenously ketamine-propofol (KP (4 mg/kg, andmaintained with continuous intravenous infusion with pre-mixed propofol (P and normal saline containing2 mg/ml of propofol and 2 mg/ml of ketamine (K. Domestic stray dogs were randomly divided into fivegroups. Groups AXKP-K2P2, AXKP-K4P4, and AXKP-K6P6 were treated with ketamine-propofol the dose0.2 mg/kg/minute, 0.4 and 0.6 mg/kg/minute respectively, while group AXKP-P4 was given propofol 0.4 mg/kg/minute and group AXKP-I was given isoflurane 1-2%. Heart rate (HR, respiratory rate (RR,electrocardiogram (ECG, blood oxygen saturation (SpO2, end tidal CO2 (ET CO2, and capillary refill time(CRT were measured. No significant difference (P>0.05 found between the groups in anaesthetion times.All groups showed rapid and smooth inductions, prolonged surgical stage, and rapid recovery. Groups AXKPK2P2and AXKP-K4P4 showed minimal physiological effect on the dogs. The HR, RR, ET CO2, SpO2, CRT,and ECG wave were stabl. Combination of AXKP-K6P6 induced SpO2 depression, increased and instabilityof HR, RR and ET CO2. Groups AXKP-P4 showed decreased of HR and respiratory depression. All anaestheticcombinations showed no significant influence (P>0.05 on the electricity of the dog’s heart. The combinationof ketamine-propofol at dose 0.2 and 0.4 mg/kg/minute were found to be better as an application formaintaining anaesthesia by gravimetric continuous intravenous infusion. The method is a suitablealternative for inhalation anaesthesia in dogs.

Primary standards for measuring flow rates from 100 nl/min to 1 ml/min - gravimetric principle.

Science.gov (United States)

Bissig, Hugo; Petter, Harm Tido; Lucas, Peter; Batista, Elsa; Filipe, Eduarda; Almeida, Nelson; Ribeiro, Luis Filipe; Gala, João; Martins, Rui; Savanier, Benoit; Ogheard, Florestan; Niemann, Anders Koustrup; Lötters, Joost; Sparreboom, Wouter

2015-08-01

Microflow and nanoflow rate calibrations are important in several applications such as liquid chromatography, (scaled-down) process technology, and special health-care applications. However, traceability in the microflow and nanoflow range does not go below 16 μl/min in Europe. Furthermore, the European metrology organization EURAMET did not yet validate this traceability by means of an intercomparison between different National Metrology Institutes (NMIs). The NMIs METAS, Centre Technique des Industries Aérauliques et Thermiques, IPQ, Danish Technological Institute, and VSL have therefore developed and validated primary standards to cover the flow rate range from 0.1 μl/min to at least 1 ml/min. In this article, we describe the different designs and methods of the primary standards of the gravimetric principle and the results obtained at the intercomparison for the upper flow rate range for the various NMIs and Bronkhorst High-Tech, the manufacturer of the transfer standards used.

Use of a non-linear method for including the mass uncertainty of gravimetric standards and system measurement errors in the fitting of calibration curves for XRFA freeze-dried UNO3 standards

International Nuclear Information System (INIS)

Pickles, W.L.; McClure, J.W.; Howell, R.H.

1978-05-01

A sophisticated nonlinear multiparameter fitting program was used to produce a best fit calibration curve for the response of an x-ray fluorescence analyzer to uranium nitrate, freeze dried, 0.2% accurate, gravimetric standards. The program is based on unconstrained minimization subroutine, VA02A. The program considers the mass values of the gravimetric standards as parameters to be fit along with the normal calibration curve parameters. The fitting procedure weights with the system errors and the mass errors in a consistent way. The resulting best fit calibration curve parameters reflect the fact that the masses of the standard samples are measured quantities with a known error. Error estimates for the calibration curve parameters can be obtained from the curvature of the ''Chi-Squared Matrix'' or from error relaxation techniques. It was shown that nondispersive XRFA of 0.1 to 1 mg freeze-dried UNO 3 can have an accuracy of 0.2% in 1000 s

Determination of oxygen in ternary uranium oxides by a gravimetric alkaline earth addition method

International Nuclear Information System (INIS)

Fujino, T.; Tagawa, H.

1979-01-01

The applicability of a gravimetric method based on alkaline earth metal addition for the determination of oxygen in ternary uranium oxides of the tupe M-U-O (M=La, Ce and Th) is described. The oxide sample is mixed with MgO or Basub(2.8)UOsub(5.8) and heated in air under suitable conditions. Because uranium is completely oxidized to the hexavalent state during the reaction, oxygen can be determined from the weight change. Oxygen in Lasub(y)Usub(1-y)Osub(2+x) is determined up to y = 0.8 with a standard deviation for x of +- 0.006 with MgO. For Thsub(y)Usub(1-y)Osub(2+x) the value of x is determined with Basub(2.8)UOsub(5.8) with a standard deviation of +- 0.01 at y = 0.8. For Cesub(y)Usub(1-y)Osub(2+x), the method can be applied only for low cerium concentrations where y = 0-0.2; the value for x with Basub(2.8)UOsub(5.8) at y = 0.2 showed a standard deviation of +- 0.002. (Auth.)

Natural gas in 1942: Petroleum in 1942: Gravimetric and magnetic geophysical surveys in the gas fields of southwestern Ontario, 1941 and 1942. Annual publication

Energy Technology Data Exchange (ETDEWEB)

Crozier, A R; Brant, A A

1946-12-31

Part V of this annual report consists of three separate reports: Natural gas; petroleum; and gravimetric and magnetic geophysical surveys in the gas fields of southwestern Ontario. The natural gas report discusses production and distribution; changes and improvements; consumption and rates; and gas wells and their production. The petroleum report presents information on production and drilling by township; expansion; and petroleum importation and refining operations. The final report discusses causes of anomalies; a discussion of the gravitational results and a discussion of the magnetic results.

A highly accurate method for determination of dissolved oxygen: Gravimetric Winkler method

International Nuclear Information System (INIS)

Helm, Irja; Jalukse, Lauri; Leito, Ivo

2012-01-01

Highlights: ► Probably the most accurate method available for dissolved oxygen concentration measurement was developed. ► Careful analysis of uncertainty sources was carried out and the method was optimized for minimizing all uncertainty sources as far as practical. ► This development enables more accurate calibration of dissolved oxygen sensors for routine analysis than has been possible before. - Abstract: A high-accuracy Winkler titration method has been developed for determination of dissolved oxygen concentration. Careful analysis of uncertainty sources relevant to the Winkler method was carried out and the method was optimized for minimizing all uncertainty sources as far as practical. The most important improvements were: gravimetric measurement of all solutions, pre-titration to minimize the effect of iodine volatilization, accurate amperometric end point detection and careful accounting for dissolved oxygen in the reagents. As a result, the developed method is possibly the most accurate method of determination of dissolved oxygen available. Depending on measurement conditions and on the dissolved oxygen concentration the combined standard uncertainties of the method are in the range of 0.012–0.018 mg dm −3 corresponding to the k = 2 expanded uncertainty in the range of 0.023–0.035 mg dm −3 (0.27–0.38%, relative). This development enables more accurate calibration of electrochemical and optical dissolved oxygen sensors for routine analysis than has been possible before.

Bouguer gravity anomalies for terrain modeling | Orupabo | Journal ...

African Journals Online (AJOL)

Gravity anomalies have been applied in geodesy to determine the geoid, and the associated composition and crustal properties of the earth. Applications of solution of the gravity inversion problems include the study of crustal dynamics as a result of the extraction of fluids in the form of oil, gas and water from ...

Testing global geopotential models through comparison of a local quasi-geoid model with GPS/leveling data

Czech Academy of Sciences Publication Activity Database

Novák, P.; Kostelecký, J.; Klokočník, Jaroslav

2009-01-01

Roč. 53, č. 1 (2009), s. 39-60 ISSN 0039-3169 R&D Projects: GA AV ČR IAA3003407; GA MŠk(CZ) LC506 Institutional research plan: CEZ:AV0Z10030501 Keywords : global geopotential model s * CHAMP * GRACE Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 1.000, year: 2009

Gravity field modeling at the sea areas using satellite altimetry observations Case study: Gravity field modeling at the Coastal Fars

International Nuclear Information System (INIS)

Jomegi, A.

2007-01-01

Nowadays, satellite altimetry observations had made it possible to determine sea surface variations, in the global scale, to high degree of precision. Using satellite altimetry observations, Mean Sea Level (MSL) can be determined, which by Kowing Sea Surface Topography (SST), can be converted into high-resolution marine geoid. In this paper we are proposing a method for computation of the Earth's gravity field at the sea areas, which is different from usual methods. Indeed, our method is based on conversion of geoidal heights into gravity potential values at the reference ellipsoid 2 Ea,b , by using ellipsoidal Brun's formula, and forward application of solution of Fixed-Free Two Boundary Value Problem (FFTBVP), previously proposed by the authors for the geoid computations without application of Stokes formula. Numerical results of application of the proposed method at the test area of CoastalFars (at southern part of Iran) show the success of the method. Considering the low cost and high precision of satellite altimetry observations, the proposed method suggests an efficient substitution to shipborne gravity observations for gravity field molding at the sea areas

A comparison of four gravimetric fine particle sampling methods.

Science.gov (United States)

Yanosky, J D; MacIntosh, D L

2001-06-01

A study was conducted to compare four gravimetric methods of measuring fine particle (PM2.5) concentrations in air: the BGI, Inc. PQ200 Federal Reference Method PM2.5 (FRM) sampler; the Harvard-Marple Impactor (HI); the BGI, Inc. GK2.05 KTL Respirable/Thoracic Cyclone (KTL); and the AirMetrics MiniVol (MiniVol). Pairs of FRM, HI, and KTL samplers and one MiniVol sampler were collocated and 24-hr integrated PM2.5 samples were collected on 21 days from January 6 through April 9, 2000. The mean and standard deviation of PM2.5 levels from the FRM samplers were 13.6 and 6.8 microg/m3, respectively. Significant systematic bias was found between mean concentrations from the FRM and the MiniVol (1.14 microg/m3, p = 0.0007), the HI and the MiniVol (0.85 microg/m3, p = 0.0048), and the KTL and the MiniVol (1.23 microg/m3, p = 0.0078) according to paired t test analyses. Linear regression on all pairwise combinations of the sampler types was used to evaluate measurements made by the samplers. None of the regression intercepts was significantly different from 0, and only two of the regression slopes were significantly different from 1, that for the FRM and the MiniVol [beta1 = 0.91, 95% CI (0.83-0.99)] and that for the KTL and the MiniVol [beta1 = 0.88, 95% CI (0.78-0.98)]. Regression R2 terms were 0.96 or greater between all pairs of samplers, and regression root mean square error terms (RMSE) were 1.65 microg/m3 or less. These results suggest that the MiniVol will underestimate measurements made by the FRM, the HI, and the KTL by an amount proportional to PM2.5 concentration. Nonetheless, these results indicate that all of the sampler types are comparable if approximately 10% variation on the mean levels and on individual measurement levels is considered acceptable and the actual concentration is within the range of this study (5-35 microg/m3).

Hawaiian Islands Terrain Corrected Free Air Anomalies (96)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This 2' gravity anomaly grid for the Principal Hawaiian Islands is NOT the input data set used in development of the GEOID96 model. This gravity grid models the...

Vibrational spectroscopic and gravimetric study of some Hofmann-CBA-Type Host and host-guest compounds

International Nuclear Information System (INIS)

Aytekin, M.A.

2005-01-01

In this study, similar to Hofmann type M(C 4 H 7 NH 2 ) 2 Ni(CN) 4 (M=Ni or Co) host and M(C 4 H 7 NH 2 ) 2 Ni(CN) 4 .nG (M=Ni or Co; G=benzene, 1,2-, 1,3-dichlorobenzene; n=the number of guest) hostguest compounds were obtained chemically. The infrared spectra of these compounds were recorded with FT-IR spectrometer in the spectroscopic region of 4000cm-1-400cm-1. From these spectra the vibrational wave numbers of ligand molecule, Ni(CN) 4 2 - ion and guest molecules were determined. The absorption and the liberation processes of the guest molecules in the host compounds were examined at room temperature by gravimetric method. Otherwise, it was seen that the molecular structure was supported by making instrumental analysis of host and some host-guest compounds. By analysing the structures of host and host-guest compounds were found to be similar to those of Hofmann type compounds, ligand molecule cyclobutylamine were coordinated to M metal atom from cyclobutylamine's nitrogen atom, the guest molecules were imprisoned in the structural cavities between the sheets

Exposure testing of fasteners in preservative treated wood: Gravimetric corrosion rates and corrosion product analyses

Energy Technology Data Exchange (ETDEWEB)

Zelinka, Samuel L., E-mail: szelinka@fs.fed.u [USDA Forest Products Laboratory, One Gifford Pinchot Drive, Madison, WI 53726 (United States); Sichel, Rebecca J. [College of Engineering, University of Wisconsin, Madison, WI 53706 (United States); Stone, Donald S. [Department of Materials Science and Engineering, College of Engineering, University of Wisconsin, Madison, WI 53706 (United States)

2010-12-15

Research highlights: {yields} The composition of the corrosion products was similar for the nail head and shank. {yields} Reduced copper was not detected on any of the fasteners. {yields} Measured corrosion rates were between 1 and 35 {mu}m year{sup -1}. - Abstract: Research was conducted to determine the corrosion rates of metals in preservative treated wood and also understand the mechanism of metal corrosion in treated wood. Steel and hot-dip galvanized steel fasteners were embedded in wood treated with one of six preservative treatments and exposed to 27 {sup o}C at 100% relative humidity for 1 year. The corrosion rate was determined gravimetrically and the corrosion products were analyzed with scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. Although the accepted mechanism of corrosion in treated wood involves the reduction of cupric ions from the wood preservative, no reduced copper was found on the corrosion surfaces. The galvanized corrosion products contained sulfates, whereas the steel corrosion products consisted of iron oxides and hydroxides. The possible implications and limitations of this research on fasteners used in building applications are discussed.

Geophysical Characterization and Structural Model of the Santa ROSALÍA Aquifer, Sonora, MÉXICO

Science.gov (United States)

Martínez-Retama, S.; Montaño-Del Cid, M. A.

2017-12-01

The main objective of this work was to determine the morphology and depth of the basement, as well as the elaboration of a structural model for the Santa Rosalía aquifer, from the processing and interpretation of gravimetric and aeromagnetic data and its correlation with the Geology of the area. The study area is located in the central portion of the State of Sonora, Mexico. In general, the geology of the site is characterized by sedimentary, igneous and metamorphic rocks whose ages vary from the Precambrian to Recent. Chronologically, the geology of the study area consists of igneous and metamorphic rocks of Precambrian age, considered as a metamorphic complex. The Paleozoic is represented by a sequence of prebatolytic rocks. This sequence is intruded by rocks of the Upper Cretaceous. The Triassic-Jurassic periods consist of arenaceous units of the Barranca Group. The Cretaceous is constituted by the Tarahumara Formation, as well as granite bodies. The Quaternary is composed of alluvial deposits, which are overlain by sediments of Recent. In this work a gravimetric survey was performed, registering a total of 7 profiles. In addition, measured data from the National Institute of Statistics and Geography (INEGI) were used. The aeromagnetic study was carried out with data from the Mexican Geological Service (SGM). In order to reduce the ambiguity in the modeling process, a rock sampling was taken from the study area and its density and magnetic susceptibility were measured. Finally, two-dimensional models of gravimetric and magnetic profiles were made to obtain the structural model of the study area. The geological-structural models obtained show gravimetric anomalies (low)associated with sedimentary basins with depths of 800 m to 1,500 m., indicating the most susceptible áreas to water storage. The basement is represented by volcanic and granite rocks that are in contact with Paleozoic sedimentary rocks (Limestone) and in some areas with volcanic rocks of the

Gravimetric analysis and differential scanning calorimetric studies on glycerin-induced skin hydration.

Science.gov (United States)

Lee, Ae-Ri Cho; Moon, Hee Kyung

2007-11-01

A thermal gravimetric analysis (TGA) and a differential scanning calorimetry (DSC) were carried out to characterize the water property and an alteration of lipid phase transition of stratum corneum (SC) by glycerin. In addition, the relationship between steady state skin permeation rate and skin hydration in various concentrations of glycerin was investigated. Water vapor absorption-desorption was studied in the hairless mouse stratum corneum. Dry SC samples were exposed to different conc. of glycerin (0-50%) followed by exposure to dry air and the change in weight property was monitored over time by use of TGA. In DSC study, significant decrease in DeltaH of the lipid transition in 10% glycerin and water treated sample: the heat of lipid transition of normal, water, 10% glycerin treated SC were 6.058, 4.412 and 4.316 mJ/mg, respectively. In 10% glycerin treated SCs, the Tc of water shifts around 129 degrees C, corresponding to the weakly bound secondary water. In 40% glycerin treated SC, the Tc of water shifts to 144 degrees C corresponding to strongly bound primary water. There was a good correlation between the hydration property of the skin and the steady state skin flux with the correlation coefficient (r2=0.94). As the hydration increased, the steady state flux increased. As glycerin concentration increased, hydration property decreased. High diffusivity induced by the hydration effect of glycerin and water could be the major contributing factor for the enhanced skin permeation of nicotinic acid (NA).

Validation of spectroscopic gas analyzer accuracy using gravimetric standard gas mixtures: impact of background gas composition on CO2 quantitation by cavity ring-down spectroscopy

Science.gov (United States)

Lim, Jeong Sik; Park, Miyeon; Lee, Jinbok; Lee, Jeongsoon

2017-12-01

The effect of background gas composition on the measurement of CO2 levels was investigated by wavelength-scanned cavity ring-down spectrometry (WS-CRDS) employing a spectral line centered at the R(1) of the (3 00 1)III ← (0 0 0) band. For this purpose, eight cylinders with various gas compositions were gravimetrically and volumetrically prepared within 2σ = 0.1 %, and these gas mixtures were introduced into the WS-CRDS analyzer calibrated against standards of ambient air composition. Depending on the gas composition, deviations between CRDS-determined and gravimetrically (or volumetrically) assigned CO2 concentrations ranged from -9.77 to 5.36 µmol mol-1, e.g., excess N2 exhibited a negative deviation, whereas excess Ar showed a positive one. The total pressure broadening coefficients (TPBCs) obtained from the composition of N2, O2, and Ar thoroughly corrected the deviations up to -0.5 to 0.6 µmol mol-1, while these values were -0.43 to 1.43 µmol mol-1 considering PBCs induced by only N2. The use of TPBC enhanced deviations to be corrected to ˜ 0.15 %. Furthermore, the above correction linearly shifted CRDS responses for a large extent of TPBCs ranging from 0.065 to 0.081 cm-1 atm-1. Thus, accurate measurements using optical intensity-based techniques such as WS-CRDS require TPBC-based instrument calibration or use standards prepared in the same background composition of ambient air.

Alaska Terrain Corrected Free Air Anomalies (96)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This 2' x 4' gravity anomaly grid for Alaska is NOT the input data set used in development of the GEOID96 model. This gravity grid models the 1.1 million terrestrial...

U.S. Terrain Corrected Free Air Anomalies (96)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This 2' gravity anomaly grid for the conterminous United States is NOT the input data set used in development of the GEOID96 model. This gravity grid models the 1.7...

PR/VI Terrain Corrected Free Air Anomalies (96)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This 2' gravity anomaly grid for the Puerto Rico and the Virgin Islands is NOT the input data set used in development of the GEOID96 model. This gravity grid models...

Gravimetric and volumetric determination of the purity of electrolytically refined silver and the produced silver nitrate

Directory of Open Access Journals (Sweden)

Ačanski Marijana M.

2007-01-01

Full Text Available Silver is, along with gold and the platinum-group metals, one of the so called precious metals. Because of its comparative scarcity, brilliant white color, malleability and resistance to atmospheric oxidation, silver has been used in the manufacture of coins and jewelry for a long time. Silver has the highest known electrical and thermal conductivity of all metals and is used in fabricating printed electrical circuits, and also as a coating for electronic conductors. It is also alloyed with other elements such as nickel or palladium for use in electrical contacts. The most useful silver salt is silver nitrate, a caustic chemical reagent, significant as an antiseptic and as a reagent in analytical chemistry. Pure silver nitrate is an intermediate in the industrial preparation of other silver salts, including the colloidal silver compounds used in medicine and the silver halides incorporated into photographic emulsions. Silver halides become increasingly insoluble in the series: AgCl, AgBr, AgI. All silver salts are sensitive to light and are used in photographic coatings on film and paper. The ZORKA-PHARMA company (Sabac, Serbia specializes in the production of pharmaceutical remedies and lab chemicals. One of its products is chemical silver nitrate (argentum-nitricum (l. Silver nitrate is generally produced by dissolving pure electrolytically refined silver in hot 48% nitric acid. Since the purity of silver nitrate, produced in 2002, was not in compliance with the p.a. level of purity, there was doubt that the electrolytically refined silver was pure. The aim of this research was the gravimetric and volumetric determination of the purity of electrolytically refined silver and silver nitrate, produced industrially and in a laboratory. The purity determination was carried out gravimetrically, by the sedimentation of silver(I ions in the form of insoluble silver salts: AgCl, AgBr and Agi, and volumetrically, according to Mohr and Volhardt. The

DNSC08 mean sea surface and mean dynamic topography models

DEFF Research Database (Denmark)

Andersen, Ole Baltazar; Knudsen, Per

2009-01-01

-2004. It is the first global MSS without a polar gap including all of the Arctic Ocean by including laser altimetry from the ICESat mission. The mean dynamic topography (MDT) is the quantity that bridges the geoid and the mean sea surface constraining large-scale ocean circulation. Here we present a new high...

A gravimetric method for the determination of oxygen in uranium oxides and ternary uranium oxides by addition of alkaline earth compounds

International Nuclear Information System (INIS)

Fujino, Takeo; Tagawa, Hiroaki; Adachi, Takeo; Hashitani, Hiroshi

1978-01-01

A simple gravimetric determination of oxygen in uranium oxides and ternary uranium oxides is described. In alkaline earth uranates which are formed by heating in air at 800-1100 0 C, uranium is in the hexavalent state over certain continuous ranges of alkaline earth-to-uranium ratios. Thus, if an alkaline earth uranate or a compound containing an alkaline earth element, e.g. MgO, is mixed with the oxide sample and heated in air under suitable conditions, oxygen can be determined from the weight change before and after the reaction. The standard deviation of the O:U ratio for a UOsub(2+x) test sample is +-0.0008-0.001, if a correction is applied for atmospheric moisture absorbed during mixing. (Auth.)

Global Models of Ridge-Push Force, Geoid, and Lithospheric Strength of Oceanic plates

Science.gov (United States)

Mahatsente, Rezene

2017-12-01

An understanding of the transmission of ridge-push related stresses in the interior of oceanic plates is important because ridge-push force is one of the principal forces driving plate motion. Here, I assess the transmission of ridge-push related stresses in oceanic plates by comparing the magnitude of the ridge-push force to the integrated strength of oceanic plates. The strength is determined based on plate cooling and rheological models. The strength analysis includes low-temperature plasticity (LTP) in the upper mantle and assumes a range of possible tectonic conditions and rheology in the plates. The ridge-push force has been derived from the thermal state of oceanic lithosphere, seafloor depth and crustal age data. The results of modeling show that the transmission of ridge-push related stresses in oceanic plates mainly depends on rheology and predominant tectonic conditions. If a lithosphere has dry rheology, the estimated strength is higher than the ridge-push force at all ages for compressional tectonics and at old ages (>75 Ma) for extension. Therefore, under such conditions, oceanic plates may not respond to ridge-push force by intraplate deformation. Instead, the plates may transmit the ridge-push related stress in their interior. For a wet rheology, however, the strength of young lithosphere (stress may dissipate in the interior of oceanic plates and diffuses by intraplate deformation. The state of stress within a plate depends on the balance of far-field and intraplate forces.

Investigating the Trimethylaluminium/Water ALD Process on Mesoporous Silica by In Situ Gravimetric Monitoring

Directory of Open Access Journals (Sweden)

Verena E. Strempel

2018-05-01

Full Text Available A low amount of AlOx was successfully deposited on an unordered, mesoporous SiO2 powder using 1–3 ALD (Atomic Layer Deposition cycles of trimethylaluminium and water. The process was realized in a self-built ALD setup featuring a microbalanceand a fixed particle bed. The reactor temperature was varied between 75, 120, and 200 °C. The self-limiting nature of the deposition was verified by in situ gravimetric monitoring for all temperatures. The coated material was further analyzed by nitrogen sorption, inductively coupled plasma-optical emission spectroscopy, powder X-ray diffraction, high-resolution transmission electron microscopy, attenuated total reflection Fourier transformed infrared spectroscopy, and elemental analysis. The obtained mass gains correspond to average growth between 0.81–1.10 Å/cycle depending on substrate temperature. In addition, the different mass gains during the half-cycles in combination with the analyzed aluminum content after one, two, and three cycles indicate a change in the preferred surface reaction of the trimethylaluminium molecule from a predominately two-ligand exchange with hydroxyl groups to more single-ligand exchange with increasing cycle number. Nitrogen sorption isotherms demonstrate (1 homogeneously coated mesopores, (2 a decrease in surface area, and (3 a reduction of the pore size. The experiment is successfully repeated in a scale-up using a ten times higher substrate batch size.

Magneto-thermo-gravimetric technique to investigate the structural and magnetic properties of Fe-B-Nb-Y Bulk Metallic Glass

Energy Technology Data Exchange (ETDEWEB)

Lee, Sangmin; Makino, Akihiro; Inoue, Akihisa [Department of Materials Science, Graduate School of Engineering, Tohoku University, Sendai 980-8579 (Japan); Masood, Ansar; Tamaki, Takahiko; Valter, Strom; Rao, K V, E-mail: smlee@imr.tohoku.ac.j [Royal Institute of Technology (KTH), SE-100 44 Stockhom (Sweden)

2009-01-01

Magneto-thermo-gravimetric (MTG) technique is highly informative about the changes in the magnetic state, as well as structural changes in a system, which cannot be often noticed in calorimetric measurements. We demonstrate the versatility of this technique in determining the magnetic transition temperature, and the subsequent crystallization process in a (Fe{sub 0.72}B{sub 0.24}Nb{sub 0.04}){sub 95.5}Y{sub 4.5} Bulk Metallic Glass (BMG). MTG and DSC analyses were carried out at the heating rate of 0.67 K/s from RT {approx}1170 K. As a result of the repeated MTG measurements, a magnetic 2nd amorphous phase was observed in the BMG sample, which could be the first measurement for the Magnetic Short Range Ordering (MSRO). Consequently, the MTG measurement is proved as the most convenient method for determining the various structural and magnetic transitions in a glassy material.

Measurement of isotope abundance variations in nature by gravimetric spiking isotope dilution analysis (GS-IDA).

Science.gov (United States)

Chew, Gina; Walczyk, Thomas

2013-04-02

Subtle variations in the isotopic composition of elements carry unique information about physical and chemical processes in nature and are now exploited widely in diverse areas of research. Reliable measurement of natural isotope abundance variations is among the biggest challenges in inorganic mass spectrometry as they are highly sensitive to methodological bias. For decades, double spiking of the sample with a mix of two stable isotopes has been considered the reference technique for measuring such variations both by multicollector-inductively coupled plasma mass spectrometry (MC-ICPMS) and multicollector-thermal ionization mass spectrometry (MC-TIMS). However, this technique can only be applied to elements having at least four stable isotopes. Here we present a novel approach that requires measurement of three isotope signals only and which is more robust than the conventional double spiking technique. This became possible by gravimetric mixing of the sample with an isotopic spike in different proportions and by applying principles of isotope dilution for data analysis (GS-IDA). The potential and principle use of the technique is demonstrated for Mg in human urine using MC-TIMS for isotopic analysis. Mg is an element inaccessible to double spiking methods as it consists of three stable isotopes only and shows great potential for metabolically induced isotope effects waiting to be explored.

Determining Coastal Mean Dynamic Topography by Geodetic Methods

Science.gov (United States)

Huang, Jianliang

2017-11-01

In geodesy, coastal mean dynamic topography (MDT) was traditionally determined by spirit leveling technique. Advances in navigation satellite positioning (e.g., GPS) and geoid determination enable space-based leveling with an accuracy of about 3 cm at tide gauges. Recent CryoSat-2, a satellite altimetry mission with synthetic aperture radar (SAR) and SAR interferometric measurements, extends the space-based leveling to the coastal ocean with the same accuracy. However, barriers remain in applying the two space-based geodetic methods for MDT determination over the coastal ocean because current geoid modeling focuses primarily on land as a substitute to spirit leveling to realize the vertical datum.

A contrastive study on the influences of radial and three-dimensional satellite gravity gradiometry on the accuracy of the Earth's gravitational field recovery

International Nuclear Information System (INIS)

Zheng Wei; Hsu Hou-Tse; Zhong Min; Yun Mei-Juan

2012-01-01

The accuracy of the Earth's gravitational field measured from the gravity field and steady-state ocean circulation explorer (GOCE), up to 250 degrees, influenced by the radial gravity gradient V zz and three-dimensional gravity gradient V ij from the satellite gravity gradiometry (SGG) are contrastively demonstrated based on the analytical error model and numerical simulation, respectively. Firstly, the new analytical error model of the cumulative geoid height, influenced by the radial gravity gradient V zz and three-dimensional gravity gradient V ij are established, respectively. In 250 degrees, the GOCE cumulative geoid height error measured by the radial gravity gradient V zz is about 2 ½ times higher than that measured by the three-dimensional gravity gradient V ij . Secondly, the Earth's gravitational field from GOCE completely up to 250 degrees is recovered using the radial gravity gradient V zz and three-dimensional gravity gradient V ij by numerical simulation, respectively. The study results show that when the measurement error of the gravity gradient is 3 × 10 −12 /s 2 , the cumulative geoid height errors using the radial gravity gradient V zz and three-dimensional gravity gradient V ij are 12.319 cm and 9.295 cm at 250 degrees, respectively. The accuracy of the cumulative geoid height using the three-dimensional gravity gradient V ij is improved by 30%–40% on average compared with that using the radial gravity gradient V zz in 250 degrees. Finally, by mutual verification of the analytical error model and numerical simulation, the orders of magnitude from the accuracies of the Earth's gravitational field recovery make no substantial differences based on the radial and three-dimensional gravity gradients, respectively. Therefore, it is feasible to develop in advance a radial cold-atom interferometric gradiometer with a measurement accuracy of 10 −13 /s 2 −10 −15 /s 2 for precisely producing the next-generation GOCE Follow-On Earth gravity field

A mantle plume model for the Equatorial Highlands of Venus

Science.gov (United States)

Kiefer, Walter S.; Hager, Bradford H.

1991-01-01

The possibility that the Equatorial Highlands are the surface expressions of hot upwelling mantle plumes is considered via a series of mantle plume models developed using a cylindrical axisymmetric finite element code and depth-dependent Newtonian rheology. The results are scaled by assuming whole mantle convection and that Venus and the earth have similar mantle heat flows. The best model fits are for Beta and Atla. The common feature of the allowed viscosity models is that they lack a pronounced low-viscosity zone in the upper mantle. The shape of Venus's long-wavelength admittance spectrum and the slope of its geoid spectrum are also consistent with the lack of a low-viscosity zone. It is argued that the lack of an asthenosphere on Venus is due to the mantle of Venus being drier than the earth's mantle. Mantle plumes may also have contributed to the formation of some smaller highland swells, such as the Bell and Eistla regions and the Hathor/Innini/Ushas region.

The Potsdam Parallel Ice Sheet Model (PISM-PIK) - Part 1: Model description

Science.gov (United States)

Winkelmann, R.; Martin, M. A.; Haseloff, M.; Albrecht, T.; Bueler, E.; Khroulev, C.; Levermann, A.

2011-09-01

We present the Potsdam Parallel Ice Sheet Model (PISM-PIK), developed at the Potsdam Institute for Climate Impact Research to be used for simulations of large-scale ice sheet-shelf systems. It is derived from the Parallel Ice Sheet Model (Bueler and Brown, 2009). Velocities are calculated by superposition of two shallow stress balance approximations within the entire ice covered region: the shallow ice approximation (SIA) is dominant in grounded regions and accounts for shear deformation parallel to the geoid. The plug-flow type shallow shelf approximation (SSA) dominates the velocity field in ice shelf regions and serves as a basal sliding velocity in grounded regions. Ice streams can be identified diagnostically as regions with a significant contribution of membrane stresses to the local momentum balance. All lateral boundaries in PISM-PIK are free to evolve, including the grounding line and ice fronts. Ice shelf margins in particular are modeled using Neumann boundary conditions for the SSA equations, reflecting a hydrostatic stress imbalance along the vertical calving face. The ice front position is modeled using a subgrid-scale representation of calving front motion (Albrecht et al., 2011) and a physically-motivated calving law based on horizontal spreading rates. The model is tested in experiments from the Marine Ice Sheet Model Intercomparison Project (MISMIP). A dynamic equilibrium simulation of Antarctica under present-day conditions is presented in Martin et al. (2011).

The gravity field and GGOS

DEFF Research Database (Denmark)

Forsberg, René; Sideris, M.G.; Shum, C.K.

2005-01-01

The gravity field of the earth is a natural element of the Global Geodetic Observing System (GGOS). Gravity field quantities are like spatial geodetic observations of potential very high accuracy, with measurements, currently at part-per-billion (ppb) accuracy, but gravity field quantities are also...... unique as they can be globally represented by harmonic functions (long-wavelength geopotential model primarily from satellite gravity field missions), or based on point sampling (airborne and in situ absolute and superconducting gravimetry). From a GGOS global perspective, one of the main challenges...... is to ensure the consistency of the global and regional geopotential and geoid models, and the temporal changes of the gravity field at large spatial scales. The International Gravity Field Service, an umbrella "level-2" IAG service (incorporating the International Gravity Bureau, International Geoid Service...

Mantle viscosity structure constrained by joint inversions of seismic velocities and density

Science.gov (United States)

Rudolph, M. L.; Moulik, P.; Lekic, V.

2017-12-01

The viscosity structure of Earth's deep mantle affects the thermal evolution of Earth, the ascent of mantle upwellings, sinking of subducted oceanic lithosphere, and the mixing of compositional heterogeneities in the mantle. Modeling the long-wavelength dynamic geoid allows us to constrain the radial viscosity profile of the mantle. Typically, in inversions for the mantle viscosity structure, wavespeed variations are mapped into density variations using a constant- or depth-dependent scaling factor. Here, we use a newly developed joint model of anisotropic Vs, Vp, density and transition zone topographies to generate a suite of solutions for the mantle viscosity structure directly from the seismologically constrained density structure. The density structure used to drive our forward models includes contributions from both thermal and compositional variations, including important contributions from compositionally dense material in the Large Low Velocity Provinces at the base of the mantle. These compositional variations have been neglected in the forward models used in most previous inversions and have the potential to significantly affect large-scale flow and thus the inferred viscosity structure. We use a transdimensional, hierarchical, Bayesian approach to solve the inverse problem, and our solutions for viscosity structure include an increase in viscosity below the base of the transition zone, in the shallow lower mantle. Using geoid dynamic response functions and an analysis of the correlation between the observed geoid and mantle structure, we demonstrate the underlying reason for this inference. Finally, we present a new family of solutions in which the data uncertainty is accounted for using covariance matrices associated with the mantle structure models.

A gravimetric method for the measurement of total spontaneous activity in rats.

Science.gov (United States)

Biesiadecki, B J; Brand, P H; Koch, L G; Britton, S L

1999-10-01

Currently available methods for the measurement of spontaneous activity of laboratory animals require expensive, specialized equipment and may not be suitable for use in low light conditions with nocturnal species. We developed a gravimetric method that uses common laboratory equipment to quantify the total spontaneous activity of rats and is suitable for use in the dark. The rat in its home cage is placed on a top-loading electronic balance interfaced to a computer. Movements are recorded by the balance as changes in weight and transmitted to the computer at 10 Hz. Data are analyzed on-line to derive the absolute value of the difference in weight between consecutive samples, and the one-second average of the absolute values is calculated. The averages are written to file for off-line analysis and summed over the desired observation period to provide a measure of total spontaneous activity. The results of in vitro experiments demonstrated that: 1) recorded weight changes were not influenced by position of the weight on the bottom of the cage, 2) values recorded from a series of weight changes were not significantly different from the calculated values, 3) the constantly decreasing force exerted by a swinging pendulum placed on the balance was accurately recorded, 4) the measurement of activity was not influenced by the evaporation of a fluid such as urine, and 5) the method can detect differences in the activity of sleeping and waking rats over a 10-min period, as well as during 4-hr intervals recorded during active (night-time) and inactive (daytime) periods. These results demonstrate that this method provides an inexpensive, accurate, and noninvasive method to quantitate the spontaneous activity of small animals.

Measuring sea surface height with a GNSS-Wave Glider

Science.gov (United States)

Morales Maqueda, Miguel Angel; Penna, Nigel T.; Foden, Peter R.; Martin, Ian; Cipollini, Paolo; Williams, Simon D.; Pugh, Jeff P.

2017-04-01

A GNSS-Wave Glider is a novel technique to measure sea surface height autonomously using the Global Navigation Satellite System (GNSS). It consists of an unmanned surface vehicle manufactured by Liquid Robotics, a Wave Glider, and a geodetic-grade GNSS antenna-receiver system, with the antenna installed on a mast on the vehicle's deck. The Wave Glider uses the differential wave motion through the water column for propulsion, thus guaranteeing an, in principle, indefinite autonomy. Solar energy is collected to power all on-board instrumentation, including the GNSS system. The GNSS-Wave Glider was first tested in Loch Ness in 2013, demonstrating that the technology is capable of mapping geoid heights within the loch with an accuracy of a few centimetres. The trial in Loch Ness did not conclusively confirm the reliability of the technique because, during the tests, the state of the water surface was much more benign than would normally be expect in the open ocean. We now report on a first deployment of a GNSS-Wave Glider in the North Sea. The deployment took place in August 2016 and lasted thirteen days, during which the vehicle covered a distance of about 350 nautical miles in the north western North Sea off Great Britain. During the experiment, the GNSS-Wave Glider experienced sea states between 1 (0-0.1 m wave heights) and 5 (2.5-4 m wave heights). The GNSS-Wave Glider data, recorded at 5 Hz frequency, were analysed using a post-processed kinematic GPS-GLONASS precise point positioning (PPP) approach, which were quality controlled using double difference GPS kinematic processing with respect to onshore reference stations. Filtered with a 900 s moving-average window, the PPP heights reveal geoid patterns in the survey area that are very similar to the EGM2008 geoid model, thus demonstrating the potential use of a GNSS-Wave Glider for marine geoid determination. The residual of subtracting the modelled or measured marine geoid from the PPP signal combines information

An initial investigation of the GOCE error variance-covariance matrices in the context of the GOCE user toolbox project

DEFF Research Database (Denmark)

Bingham, Rory J.; Tscherning, Christian; Knudsen, Per

2011-01-01

The availability of the full error variance-covariance matrices for the GOCE gravity field models is an important feature of the GOCE mission. Potentially, it will allow users to evaluate the accuracy of a geoid or mean dynamic topography (MDT) derived from the gravity field model at any particul...

The kinetic of mass loss of grades A and B of melted TNT by isothermal and non-isothermal gravimetric methods

Directory of Open Access Journals (Sweden)

Hamid Reza Pouretedal

2018-04-01

Full Text Available The kinetic and activation energy of mass loss of two grades of melted TNT explosive, grade A and grade B, with freezing points of 80.57 and 78.15 °C, respectively, were studied by isothermal and non-isothermal gravimetric methods. In isothermal method, the mass loss of samples in containers of glass and aluminum was followed in temperatures of 80, 90 and 100 °C. The kinetic of the mass loss of the samples in the aluminum container was higher than the kinetic of it in the glass container that can be related to the effects of heat transfer and catalytic of aluminum metal. Also, the presence of impurities in grade B was due to increasing of kinetic of mass loss of it versus grade A. The non-isothermal curves were obtained in range of 30–330 °C at heating rates of 10, 15 and 20 °C⋅min−1. The TG/DTG data were used for determination of activation energy (Ea of mass loss of TNT samples upon degradation by using Ozawa, Kissinger, Ozawa-Flynn-Wall (OFW and Kissinger-Akahira-Sunose (KAS methods as model free methods. The activation energies of grades of A and B of TNT was obtained 99–120 and 66–70 kJ mol−1, respectively. The lower values of activation energy of the degradation reaction of grade B confirm the effect of impurities in the kinetics of mass loss of this grade. Keywords: TNT, Isothermal, Non-isothermal, Kinetic, Mass loss

Determination of insoluble, soluble, and total dietary fiber (CODEX definition) by enzymatic-gravimetric method and liquid chromatography: collaborative study.

Science.gov (United States)

McCleary, Barry V; DeVries, Jonathan W; Rader, Jeanne I; Cohen, Gerald; Prosky, Leon; Mugford, David C; Okuma, Kazuhiro

2012-01-01

A method for the determination of insoluble (IDF), soluble (SDF), and total dietary fiber (TDF), as defined by the CODEX Alimentarius, was validated in foods. Based upon the principles of AOAC Official Methods 985.29, 991.43, 2001.03, and 2002.02, the method quantitates water-insoluble and water-soluble dietary fiber. This method extends the capabilities of the previously adopted AOAC Official Method 2009.01, Total Dietary Fiber in Foods, Enzymatic-Gravimetric-Liquid Chromatographic Method, applicable to plant material, foods, and food ingredients consistent with CODEX Definition 2009, including naturally occurring, isolated, modified, and synthetic polymers meeting that definition. The method was evaluated through an AOAC/AACC collaborative study. Twenty-two laboratories participated, with 19 laboratories returning valid assay data for 16 test portions (eight blind duplicates) consisting of samples with a range of traditional dietary fiber, resistant starch, and nondigestible oligosaccharides. The dietary fiber content of the eight test pairs ranged from 10.45 to 29.90%. Digestion of samples under the conditions of AOAC 2002.02 followed by the isolation, fractionation, and gravimetric procedures of AOAC 985.29 (and its extensions 991.42 and 993.19) and 991.43 results in quantitation of IDF and soluble dietary fiber that precipitates (SDFP). The filtrate from the quantitation of water-alcohol-insoluble dietary fiber is concentrated, deionized, concentrated again, and analyzed by LC to determine the SDF that remains soluble (SDFS), i.e., all dietary fiber polymers of degree of polymerization = 3 and higher, consisting primarily, but not exclusively, of oligosaccharides. SDF is calculated as the sum of SDFP and SDFS. TDF is calculated as the sum of IDF and SDF. The within-laboratory variability, repeatability SD (Sr), for IDF ranged from 0.13 to 0.71, and the between-laboratory variability, reproducibility SD (SR), for IDF ranged from 0.42 to 2.24. The within

Upper mantle compositional variations and discontinuity topography imaged beneath Australia from Bayesian inversion of surface-wave phase velocities and thermochemical modeling

DEFF Research Database (Denmark)

Khan, A.; Zunino, Andrea; Deschamps, F.

2013-01-01

Here we discuss the nature of velocity heterogeneities seen in seismic tomography images of Earth's mantle whose origins and relation to thermochemical variations are yet to be understood. We illustrate this by inverting fundamental-mode and higher-order surface-wave phase velocities for radial....../Fe and Mg/Si values relative to surrounding mantle. Correlated herewith are thermal variations that closely follow surface tectonics. We also observe a strong contribution to lateral variations in structure and topography across the “410 km” seismic discontinuity from thermochemically induced phase......-wave tomography models with other regional models is encouraging. Radial anisotropy is strongest at 150/200 km depth beneath oceanic/continental areas, respectively, and appears weak and homogeneous below. Finally, geoid anomalies are computed for a subset of sampled model and compared to observations....

Theoretical and Applied Research in the Field of Higher Geodesy Conducted in Rzeszow

Directory of Open Access Journals (Sweden)

Kadaj Roman

2016-06-01

Full Text Available Important qualitative changes were taking place in polish geodesy in last few years. It was related to application of new techniques and technologies and to introduction of European reference frames in Poland. New reference stations network ASG-EUPOS, together with Internet services which helps in precise positioning was created. It allows to fast setting up precise hybrid networks. New, accurate satellite networks became the basis of new definitions in the field of reference systems. Simultaneously arise the need of new software, which enables to execute the geodetic works in new technical conditions. Authors had an opportunity to participate in mentioned undertakings, also under the aegis of GUGiK, by creation of methods, algorithms and necessary software tools. In this way the automatic postprocessing module (APPS in POZGEO service, a part of ASG-EUPOS system came into being. It is an entirely polish product which works in Trimble environment. Universal software for transformation between PLETRF89, PL-ETRF2000, PULKOWO’42 reference systems as well as defined coordinate systems was created (TRANSPOL v. 2.06 and published as open product. An essential functional element of the program is the quasi-geoid model PL-geoid-2011, which has been elaborated by adjustment (calibration of the global quasi-geoid model EGM2008 to 570 geodetic points (satellite-leveling points. Those and other studies are briefly described in this paper.

Validation of ERS-1 and high-resolution satellite gravity with in-situ shipborne gravity over the Indian offshore regions: Accuracies and implications to subsurface modeling

Digital Repository Service at National Institute of Oceanography (India)

Chatterjee, S.; Bhattacharyya, R.; Michael, L.; Krishna, K.S.; Majumdar, T.J.

Geoid and gravity anomalies derived from satellite altimetry are gradually gaining importance in marine geoscientific investigations. Keeping this in mind, we have validated ERS-1 (168 day repeat) altimeter data and very high-resolution free...

Determination of the parameters of binding between lipopolysaccharide and chitosan and its N-acetylated derivative using a gravimetric piezoquartz biosensor.

Science.gov (United States)

Naberezhnykh, G A; Gorbach, V I; Kalmykova, E N; Solov'eva, T F

2015-03-01

The interaction of endotoxin (lipopolysaccharide - LPS) with low molecular weight chitosan (5.5 kDa), its N-acylated derivative and chitoliposomes was studied using a gravimetric piezoelectric quartz crystal microbalance biosensor. The optimal conditions for the formation of a biolayer based on immobilized LPS on the resonator surface and its regeneration were elaborated. The association and dissociation rate constants for LPS binding to chitosans were determined and the affinity constants (Kaf) were calculated based on the data on changes in the oscillation frequency of the quartz crystal resonator. The Kaf values correlated with the ones obtained using other methods. The affinity of N-acylated chitosan binding to LPS was higher than that of the parent chitosan binding to LPS. Based on the results obtained, we suggest that water-soluble N-acylated derivatives of chitosan with low degree of substitution of amino groups could be useful compounds for endotoxin binding and neutralization. Copyright © 2015 Elsevier B.V. All rights reserved.

Corrosion of experimental magnesium alloys in blood and PBS: A gravimetric and microscopic evaluation

International Nuclear Information System (INIS)

Schille, Ch.; Braun, M.; Wendel, H.P.; Scheideler, L.; Hort, N.; Reichel, H.-P.; Schweizer, E.; Geis-Gerstorfer, J.

2011-01-01

Highlights: ► Corrosion of eight Mg–based Biomaterials was tested in saline and human blood. ► Corrosion behaviour in physiological saline and in blood was entirely different. ► Al and Zn had the highest influence on corrosion behaviour in both electrolytes. ► MgAl9 and MgAl9Zn1 showed least corrosion in human whole blood. ► Tests in buffered corrosion media are not sufficient to predict corrosion in vivo. - Abstract: Corrosion tests for medical materials are often performed in simulated body fluids (SBF). When SBF are used for corrosion measurement, the open question is, how well they match the conditions in the human body. The aim of the study was to compare the corrosion behaviour of different experimental magnesium alloys in human whole blood and PBS minus (phosphate buffered saline w/o Ca and Mg) as a simulated body fluid by gravimetric weight measurements and microscopic evaluation. Eight different experimental magnesium alloys, containing neither Mn nor other additives, were manufactured. With these alloys, a static immersion test in PBS minus and a dynamic test using the Chandler-loop model with human whole blood over 6 h were performed. During the static immersion test, the samples were weighed every hour. During the dynamic test, the specimens were weighed before and after the 6 h incubation period in the Chandler-loop. From both tests, the total mass change was calculated for each alloy and the values were compared. Additionally, microscopic pictures from the samples were taken at the end of the test period. All alloys showed different corrosion behaviour in both tests, especially the alloys with high aluminium content, MgAl9 and MgAl9Zn1. Generally, alloys in PBS showed a weight gain due to generation of a microscopically visible corrosion layer, while in the blood test system a more or less distinct weight loss was observed. When alloys are ranked according to corrosion susceptibility, the results differ also between the test systems. The

A dynamic model of Venus's gravity field

Science.gov (United States)

Kiefer, W. S.; Richards, M. A.; Hager, B. H.; Bills, B. G.

1984-01-01

Unlike Earth, long wavelength gravity anomalies and topography correlate well on Venus. Venus's admittance curve from spherical harmonic degree 2 to 18 is inconsistent with either Airy or Pratt isostasy, but is consistent with dynamic support from mantle convection. A model using whole mantle flow and a high viscosity near surface layer overlying a constant viscosity mantle reproduces this admittance curve. On Earth, the effective viscosity deduced from geoid modeling increases by a factor of 300 from the asthenosphere to the lower mantle. These viscosity estimates may be biased by the neglect of lateral variations in mantle viscosity associated with hot plumes and cold subducted slabs. The different effective viscosity profiles for Earth and Venus may reflect their convective styles, with tectonism and mantle heat transport dominated by hot plumes on Venus and by subducted slabs on Earth. Convection at degree 2 appears much stronger on Earth than on Venus. A degree 2 convective structure may be unstable on Venus, but may have been stabilized on Earth by the insulating effects of the Pangean supercontinental assemblage.

Análisis de nuevos estándares para reducir datos de gravedad: aplicación en Tierra del Fuego

Directory of Open Access Journals (Sweden)

Ana Carolina Pedraza De Marchi

2011-12-01

reducing gravity data in order to improve the precision, accuracy, and usefulness of geophysical gravity anomalies. The new standards take into account the increased current computing power, the modern satellite technology to determine the height and positioning of the gravity stations, the improved topographic / bathymetric databases, and new mathematical algorithms. They are based on internationally accepted procedures, protocols, equations and parameters, and in many cases differ from those presented in current geophysical textbooks and existing gravity databases. The most important change that the new standards suggest, due to the greater use of Global Positioning System (GPS for field gravimetric work, is the use of terrestrial reference ellipsoid adopted internationally to define the vertical datum. The anomalies calculated with the new standards could be modified by the adjective "ellipsoidal" to differentiate them from the anomalies calculated by conventional elevations referred to the geoid. Gravity reductions, following the traditional and new recommendations and standards were calculated in the province of Tierra del Fuego. We used digital elevation models and geopotential models to assess the effectiveness of its use in gravity reductions. The land gravimetric data were integrated with free air anomalies derived from satellite altimetry in the sea, in order to compute an ellipsoidal isostatic anomaly map.

The Potsdam Parallel Ice Sheet Model (PISM-PIK – Part 1: Model description

Directory of Open Access Journals (Sweden)

R. Winkelmann

2011-09-01

Full Text Available We present the Potsdam Parallel Ice Sheet Model (PISM-PIK, developed at the Potsdam Institute for Climate Impact Research to be used for simulations of large-scale ice sheet-shelf systems. It is derived from the Parallel Ice Sheet Model (Bueler and Brown, 2009. Velocities are calculated by superposition of two shallow stress balance approximations within the entire ice covered region: the shallow ice approximation (SIA is dominant in grounded regions and accounts for shear deformation parallel to the geoid. The plug-flow type shallow shelf approximation (SSA dominates the velocity field in ice shelf regions and serves as a basal sliding velocity in grounded regions. Ice streams can be identified diagnostically as regions with a significant contribution of membrane stresses to the local momentum balance. All lateral boundaries in PISM-PIK are free to evolve, including the grounding line and ice fronts. Ice shelf margins in particular are modeled using Neumann boundary conditions for the SSA equations, reflecting a hydrostatic stress imbalance along the vertical calving face. The ice front position is modeled using a subgrid-scale representation of calving front motion (Albrecht et al., 2011 and a physically-motivated calving law based on horizontal spreading rates. The model is tested in experiments from the Marine Ice Sheet Model Intercomparison Project (MISMIP. A dynamic equilibrium simulation of Antarctica under present-day conditions is presented in Martin et al. (2011.

Airborne gravity field Measurements - status and developments

DEFF Research Database (Denmark)

Olesen, Arne Vestergaard; Forsberg, René

2016-01-01

English Abstract:DTU-Space has since 1996 carried out large area airborne surveys over both polar, tropical and temperate regions, especially for geoid determination and global geopotential models. Recently we have started flying two gravimeters (LCR and Chekan-AM or inertial navigation systems) ...

Understanding of thermo-gravimetric analysis to calculate number of addends in multifunctional hemi-ortho ester derivatives of fullerenol

International Nuclear Information System (INIS)

Singh, Rachana; Goswami, Thakohari

2011-01-01

Test results for the applicability of existing thermo-gravimetric analysis (TGA) technique to ascertain average number of exohedral chemical attachment in a new class of fullerene dyads consisting of multiple hemi-ortho esters onto fullerenol is presented. Although the method is nicely applicable for higher fullerenol, but homogeneous phase products calculate lower number of addends, whereas, the hetero phase products indicate higher value. Lower value is attributed to either overlapping of thermal events or substituents effects and higher value is the contribution of tetra butyl ammonium hydroxide (TBAH) impurity used as phase transfer catalyst (PTC) in heterogeneous phase reactions. Presence of TBAH impurity is recognized through thermo-gravimetry mass spectrometry (TG-MS) measurement. Appropriate modification of test method to arrive at accurate and precise values of x (total mass contribution due to addends only) and y (total mass contribution due to fullerene plus char yield) are also reported. Successful use of two more different techniques, viz., electron-spray ionization mass spectrometry (ESI-MS) and X-ray photoelectron spectroscopy (XPS), supplement above results. Influences of fullerene and different substituents on thermal behavior of dyads are assessed.

Quantification of in vitro wear of a synthetic meniscus implant using gravimetric and micro-CT measurements.

Science.gov (United States)

Elsner, Jonathan J; Shemesh, Maoz; Shefy-Peleg, Adaya; Gabet, Yankel; Zylberberg, Eyal; Linder-Ganz, Eran

2015-09-01

A synthetic meniscus implant was recently developed for the treatment of patients with mild to moderate osteoarthritis with knee pain associated with medial joint overload. The implant is distinctively different from most orthopedic implants in its pliable construction, and non-anchored design, which enables implantation through a mini-arthrotomy without disruption to the bone, cartilage, and ligaments. Due to these features, it is important to show that the material and design can withstand knee joint conditions. This study evaluated the long-term performance of this device by simulating loading for a total of 5 million gait cycles (Mc), corresponding to approximately five years of service in-vivo. All five implants remained in good condition and did not dislodge from the joint space during the simulation. Mild abrasion was detected by electron microscopy, but µ-CT scans of the implants confirmed that the damage was confined to the superficial surfaces. The average gravimetric wear rate was 14.5 mg/Mc, whereas volumetric changes in reconstructed µ-CT scans point to an average wear rate of 15.76 mm(3)/Mc (18.8 mg/Mc). Particles isolated from the lubricant had average diameter of 15 µm. The wear performance of this polycarbonate-urethane meniscus implant concept under ISO-14243 loading conditions is encouraging. Copyright © 2015 Elsevier Ltd. All rights reserved.

Novel in situ multiharmonic EQCM-D approach to characterize complex carbon pore architectures for capacitive deionization of brackish water

International Nuclear Information System (INIS)

Shpigel, Netanel; Levi, Mikhael D; Sigalov, Sergey; Aurbach, Doron; Daikhin, Leonid; Presser, Volker

2016-01-01

Multiharmonic analysis by electrochemical quartz-crystal microbalance with dissipation monitoring (EQCM-D) is introduced as an excellent tool for quantitative studying electrosorption of ions from aqueous solution in mesoporous (BP-880) or mixed micro-mesoporous (BP-2000) carbon electrodes. Finding the optimal conditions for gravimetric analysis of the ionic content in the charged carbon electrodes, we propose a novel approach to modeling the charge-dependent gravimetric characteristics by incorporation of Gouy-Chapman-Stern electric double layer model for ions electrosorption into meso- and micro-mesoporous carbon electrodes. All three parameters of the gravimetric equation evaluated by fitting it to the experimental mass changes curves were validated using supplementary nitrogen gas sorption analysis and complementing atomic force microscopy. Important overlap between gravimetric EQCM-D analysis of the ionic content of porous carbon electrodes and the classical capacitive deionization models has been established. The necessity and usefulness of non-gravimetric EQCM-D characterizations of complex carbon architectures, providing insight into their unique viscoelastic behavior and porous structure changes, have been discussed in detail. (paper)

Towards worldwide height unification using ocean information

Directory of Open Access Journals (Sweden)

P. L. Woodworth

2015-03-01

Full Text Available This paper describes how we are contributing to worldwide height system unification (WHSU by using ocean models together with sea level (tide gauge and altimeter information, geodetic (GPS and levelling data, and new geoid models based on information from the GRACE and GOCE gravity missions, to understand how mean sea level (MSL varies from place to place along the coast. For the last two centuries, MSL has been used to define datums for national levelling systems. However, there are many problems with this. One consequence of WHSU will be the substitution of conventional datums as a reference for heights with the use of geoid, as the only true "level" or datum. This work is within a number of GOCE-related activities funded by the European Space Agency. The study is focused on the coastlines of North America and Europe where the various datasets are most copious.

Journal of Earth System Science | Indian Academy of Sciences

Indian Academy of Sciences (India)

Precise information of geoid undulations is essential for obtaining the orthometric heights from Global Positioning System (GPS) measurements over any region; apart from providing the information of subsurface density distribution. This paper presents computation of geoid undulations over a part of southern Indian region ...

Direct gravimetric measurements of the mass of the antarctic aerosol collected by high volume sampler: PM10 summer seasonal variation at Terra Nova Bay.

Science.gov (United States)

Truzzi, Cristina; Lambertucci, Luca; Illuminati, Silvia; Annibaldi, Anna; Scarponi, Giuseppe

2005-01-01

An on-site procedure was set up for direct gravimetric measurement of the mass of aerosol collected using high volume impactors (aerodynamic size cut point of 10 microm, PM10); this knowledge has hitherto been unavailable. Using a computerized microbalance in a clean chemistry laboratory, under controlled temperature (+/-0.5 degrees C) and relative humidity (+/-1%), continuous, long time filter mass measurements (hours) were carried out before and after exposure, after a 48 h minimun equilibration at the laboratory conditions. The effect of the electrostatic charge was exhausted in 30-60 min, after which stable measurements were obtained. Measurements of filters exposed for 7-11 days (1.13 m3 min(-1)) in a coastal site near Terra Nova Bay (December 2000 - February 2001), gave results for aerosol mass in the order of 10-20 mg (SD approximately 2 mg), corresponding to atmospheric concentrations of 0.52-1.27 microg m(-3). Data show a seasonal behaviour in the PM10 content with an increase during December - early January, followed by a net decrease. The above results compare well with estimates obtained from proxy data for the Antarctic Peninsula (0.30 microg m(-3)), the Ronne Ice Shelf (1.49 microg m(-3)), and the South Pole (0.18 microg m(-3), summer 1974-1975, and 0.37 microg m(-3), average summer seasons 1975-1976 and 1977-1978), and from direct gravimetric measurements recently obtained from medium volume samplers at McMurdo station (downwind 3.39 microg m(-3), upwind 4.15 microg m(-3)) and at King George Island (2.5 microg m(-3), summer, particle diameter <20 microm). This finding opens the way to the direct measurement of the chemical composition of the Antarctic aerosol and, in turn, to a better knowledge of the snow/air relationships as required for the reconstruction of the chemical composition of past atmospheres from deep ice core data.

Greenland uplift and regional sea level changes from ICESat observations and GIA modelling

DEFF Research Database (Denmark)

Spada, G.; Ruggieri, G.; Sørensen, Louise Sandberg

2012-01-01

‐resolution GrIS mass balance, we study the time‐variations of various geophysical quantities in response to the current mass loss. They include vertical uplift and subsidence, geoid height variations, global patterns of sea level change (or fingerprints), and regional sea level variations along the coasts...... of Greenland. Long‐wavelength uplifts and gravity variations in response to current or past ice thickness variations are obtained solving the sea level equation, which accounts for both the elastic and the viscoelastic components of deformation. To capture the short‐wavelength components of vertical uplift...... in response to current ice mass loss, which is not resolved by satellite gravity observations, we have specifically developed a high‐resolution regional elastic rebound (ER) model. The elastic component of vertical uplift is combined with estimates of the viscoelastic displacement fields associated...

Corrosion of experimental magnesium alloys in blood and PBS: A gravimetric and microscopic evaluation

Energy Technology Data Exchange (ETDEWEB)

Schille, Ch., E-mail: Christine.Schille@med.uni-tuebingen.de [University Hospital Tuebingen, Center for Dentistry, Oral Medicine and Maxillofacial Surgery, Section Medical Materials and Technology, Osianderstr. 2-8, D-72076 Tuebingen (Germany); Braun, M.; Wendel, H.P. [University Hospital Tuebingen, Div. Congenital and Paediatric Cardiac Surgery, University Children' s Hospital, Tuebingen, Germany, Calwerstr. 7/1, D-72076 Tuebingen (Germany); Scheideler, L. [University Hospital Tuebingen, Center for Dentistry, Oral Medicine and Maxillofacial Surgery, Section Medical Materials and Technology, Osianderstr. 2-8, D-72076 Tuebingen (Germany); Hort, N. [GKSS Research Centre, Institute of Materials Research, Max-Planck-Str. 1, D-21502 Geesthacht (Germany); Reichel, H.-P. [Weissensee Company, Buergermeister-Ebert-Str. 30-32, D-36124 Eichenzell (Germany); Schweizer, E.; Geis-Gerstorfer, J. [University Hospital Tuebingen, Center for Dentistry, Oral Medicine and Maxillofacial Surgery, Section Medical Materials and Technology, Osianderstr. 2-8, D-72076 Tuebingen (Germany)

2011-12-15

Highlights: Black-Right-Pointing-Pointer Corrosion of eight Mg-based Biomaterials was tested in saline and human blood. Black-Right-Pointing-Pointer Corrosion behaviour in physiological saline and in blood was entirely different. Black-Right-Pointing-Pointer Al and Zn had the highest influence on corrosion behaviour in both electrolytes. Black-Right-Pointing-Pointer MgAl9 and MgAl9Zn1 showed least corrosion in human whole blood. Black-Right-Pointing-Pointer Tests in buffered corrosion media are not sufficient to predict corrosion in vivo. - Abstract: Corrosion tests for medical materials are often performed in simulated body fluids (SBF). When SBF are used for corrosion measurement, the open question is, how well they match the conditions in the human body. The aim of the study was to compare the corrosion behaviour of different experimental magnesium alloys in human whole blood and PBS{sup minus} (phosphate buffered saline w/o Ca and Mg) as a simulated body fluid by gravimetric weight measurements and microscopic evaluation. Eight different experimental magnesium alloys, containing neither Mn nor other additives, were manufactured. With these alloys, a static immersion test in PBS{sup minus} and a dynamic test using the Chandler-loop model with human whole blood over 6 h were performed. During the static immersion test, the samples were weighed every hour. During the dynamic test, the specimens were weighed before and after the 6 h incubation period in the Chandler-loop. From both tests, the total mass change was calculated for each alloy and the values were compared. Additionally, microscopic pictures from the samples were taken at the end of the test period. All alloys showed different corrosion behaviour in both tests, especially the alloys with high aluminium content, MgAl9 and MgAl9Zn1. Generally, alloys in PBS showed a weight gain due to generation of a microscopically visible corrosion layer, while in the blood test system a more or less distinct weight

Mapping ocean tides with satellites - A computer simulation

Science.gov (United States)

Won, I. J.; Kuo, J. T.; Jachens, R. C.

1978-01-01

As a preliminary study for the future worldwide direct mapping of the open ocean tide with satellites equipped with precision altimeters we conducted a simulated study using sets of artificially generated altimeter data constructed from a realistic geoid and four pairs of major tides in the northeastern Pacific Ocean. Recovery of the original geoid and eight tidal maps is accomplished by a space-time, least squares harmonic analysis scheme. The resultant maps appear fairly satisfactory even when random noises up to + or - 100 cm are added to the altimeter data of sufficient space-time density. The method also produces a refined geoid which is rigorously corrected for the dynamic tides.

Mean Dynamic Topography of the Arctic Ocean

Science.gov (United States)

Farrell, Sinead Louise; Mcadoo, David C.; Laxon, Seymour W.; Zwally, H. Jay; Yi, Donghui; Ridout, Andy; Giles, Katherine

2012-01-01

ICESat and Envisat altimetry data provide measurements of the instantaneous sea surface height (SSH) across the Arctic Ocean, using lead and open water elevation within the sea ice pack. First, these data were used to derive two independent mean sea surface (MSS) models by stacking and averaging along-track SSH profiles gathered between 2003 and 2009. The ICESat and Envisat MSS data were combined to construct the high-resolution ICEn MSS. Second, we estimate the 5.5-year mean dynamic topography (MDT) of the Arctic Ocean by differencing the ICEn MSS with the new GOCO02S geoid model, derived from GRACE and GOCE gravity. Using these satellite-only data we map the major features of Arctic Ocean dynamical height that are consistent with in situ observations, including the topographical highs and lows of the Beaufort and Greenland Gyres, respectively. Smaller-scale MDT structures remain largely unresolved due to uncertainties in the geoid at short wavelengths.

Climate model biases in seasonality of continental water storage revealed by satellite gravimetry

Science.gov (United States)

Swenson, Sean; Milly, P.C.D.

2006-01-01

Satellite gravimetric observations of monthly changes in continental water storage are compared with outputs from five climate models. All models qualitatively reproduce the global pattern of annual storage amplitude, and the seasonal cycle of global average storage is reproduced well, consistent with earlier studies. However, global average agreements mask systematic model biases in low latitudes. Seasonal extrema of low‐latitude, hemispheric storage generally occur too early in the models, and model‐specific errors in amplitude of the low‐latitude annual variations are substantial. These errors are potentially explicable in terms of neglected or suboptimally parameterized water stores in the land models and precipitation biases in the climate models.

Evaluation and mapping of PM{sub 2.5} atmospheric aerosols in Arasia region using PIXE and gravimetric measurements

Energy Technology Data Exchange (ETDEWEB)

Roumie, M. [Accelerator Laboratory, Lebanese Atomic Energy Commission, CNRSL, Beirut (Lebanon); Chiari, M. [INFN, Firenze and Department of Physics and Astronomy, University of Florence, Florence (Italy); Srour, A. [Accelerator Laboratory, Lebanese Atomic Energy Commission, CNRSL, Beirut (Lebanon); Sa’adeh, H. [Department of Physics, Faculty of Science, University of Jordan, Amman (Jordan); Reslan, A. [Accelerator Laboratory, Lebanese Atomic Energy Commission, CNRSL, Beirut (Lebanon); Sultan, M. [Ministry of Science and Technology MOST, Baghdad (Iraq); Ahmad, M. [Atomic Energy Commission of Syria AECS, Damascus (Syrian Arab Republic); Calzolai, G.; Nava, S. [INFN, Firenze and Department of Physics and Astronomy, University of Florence, Florence (Italy); Zubaidi, Th. [Ministry of Science and Technology MOST, Baghdad (Iraq); Rihawy, M.S. [Atomic Energy Commission of Syria AECS, Damascus (Syrian Arab Republic); Hussein, T. [Department of Physics, Faculty of Science, University of Jordan, Amman (Jordan); Department of Physics, Division of Atmospheric Sciences, University of Helsinki, Helsinki (Finland); Arafah, D.-E. [Department of Physics, Faculty of Science, University of Jordan, Amman (Jordan); Karydas, A.G.; Simon, A. [International Atomic Energy Agency IAEA, Vienna (Austria); Nsouli, B. [Accelerator Laboratory, Lebanese Atomic Energy Commission, CNRSL, Beirut (Lebanon)

2016-03-15

The present work is a part of a scientific study conducted among several Arab countries in west Asia, under an International Atomic Energy Agency (IAEA) regional technical cooperation project for Arasia region. The project aims at producing for the first time a database of particulate matter (PM) elemental concentrations in the region that will help in future air quality studies in order to identify commonalities and differences in the presence and contribution of fingerprint pollution sources among the Arasia Member States. The first regional campaign was launched simultaneously in Lebanon, Iraq, Jordan, Syria and United Arab Emirates, using a harmonized sampling and analysis protocol of PM{sub 10} and PM{sub 2.5} samples. Different samples, collected between October 2014 and February 2015, from the participating countries, were analyzed by PIXE technique and gravimetric measurements were also carried out. The first results of the study will be discussed in a regional perspective. Our study shows that concentrations of fine aerosol fractions are often exceeding the WHO standard values as well as showing some disparities in the obtained values between the different sampling sites. However, some trend similarities of variations with time could also be observed, suggesting a common influence by trans-boundary or external sources of air pollution.

Method for the Collection, Gravimetric and Chemical Analysis of Nonvolatile Residue (NVR) on Surfaces

Science.gov (United States)

Gordon, Keith; Rutherford, Gugu; Aranda, Denisse

2017-01-01

Nonvolatile residue (NVR), sometimes referred to as molecular contamination is the term used for the total composition of the inorganic and high boiling point organic components in particulates and molecular films deposited on critical surfaces surrounding space structures, with the particulate and NVR contamination originating primarily from pre-launch operations. The "nonvolatile" suggestion from the terminology NVR implies that the collected residue will not experience much loss under ambient conditions. NVR has been shown to have a dramatic impact on the ability to perform optical measurements from platforms based in space. Such contaminants can be detected early by the controlled application of various detection techniques and contamination analyses. Contamination analyses are the techniques used to determine if materials, components, and subsystems can be expected to meet the performance requirements of a system. Of particular concern is the quantity of NVR contaminants that might be deposited on critical payload surfaces from these sources. Subsequent chemical analysis of the contaminant samples by infrared spectroscopy and gas chromatography mass spectrometry identifies the components, gives semi-quantitative estimates of contaminant thickness, indicates possible sources of the NVR, and provides guidance for effective cleanup procedures. In this report, a method for the collection and determination of the mass of NVR was generated by the authors at NASA Langley Research Center. This report describes the method developed and implemented for collecting NVR contaminants, and procedures for gravimetric and chemical analysis of the residue obtained. The result of this NVR analysis collaboration will help pave the way for Langley's ability to certify flight hardware outgassing requirements in support of flight projects such as Stratospheric Aerosol and Gas Experiment III (SAGE III), Clouds and the Earth's Radiant Energy System (CERES), Materials International

A three-dimensional model of the Pyrenees and their foreland basins from geological and gravimetric data

Science.gov (United States)

Wehr, H.; Chevrot, S.; Courrioux, G.; Guillen, A.

2018-06-01

We construct a three-dimensional geological model of the Pyrenees and their foreland basins with the Geomodeller. This model, which accounts for different sources of geological and geophysical informations, covers the whole Pyrenees, from the Atlantic Ocean to the Mediterranean Sea, and from the Iberian range to the Massif Central, down to 70 km depth. We model the geological structure with a stratigraphic column composed of a superposition of layers representing the mantle, lower, middle, and upper crusts. The sedimentary basins are described by two layers which allow us to make the distinction between Mesozoic and Cenozoic sediments, which are characterized by markedly different densities and seismic velocities. Since the Pyrenees result from the convergence between the Iberian and European plates, we ascribe to each plate its own stratigraphic column in order to be able to model the imbrication of Iberian and European crusts along this fossile plate boundary. We also introduce two additional units which describe the orogenic prism and the water column in the Bay of Biscay and in the Mediterranean Sea. The last ingredient is a unit that represents bodies of shallow exhumed and partly serpentinized lithospheric mantle, which are assumed to produce the positive Bouguer gravity anomalies in the North Pyrenean Zone. A first 3D model is built using only the geological information coming from geological maps, drill-holes, and seismic sections. We use the potential field method implemented in Geomodeller to interpolate these geological data. This model is then refined in order to better explain the observed Bouguer anomalies by adding new constraints on the main crustal interfaces. The final model explains the observed Bouguer anomalies with a standard deviation less than 3.4 mGal, and reveals anomalous deep structures beneath the eastern Pyrenees.

Comparison between different models for rheological characterization of sludge from settling tank

Directory of Open Access Journals (Sweden)

Malczewska Beata

2017-09-01

Full Text Available The municipal sludge characterized non-Newtonian behaviour, therefore the viscosity of the sewage sludge is not a constant value. The laboratory investigation was made using coaxial cylinder with rotating torque and gravimetric concentration of the investigated sludge ranged from 4.40% to 2.09%. This paper presents the investigation on the effect of concentration of rheological sludge behaviour. The three different rheological models: Bingham (plastic model, Ostwald-de Waele (power-law, Hershel-Bulkley’s were calculated by fitting the experimental data of shear stress as a function of shear rate to these models. In this study, the 3-parameter Herschel- Bulkley’s model fits the experimental data best.

Application of the gravimetric method to closing the material balance around the chop-leach cell of a spent-fuel reprocessing plant

International Nuclear Information System (INIS)

Fishbone, L.G.

1985-01-01

For a spent-fuel reprocessing plant handling commercial light-water-reactor fuel, plutonium accounting is traditionally done for the material balance area (MBA) extending from the input accountability tank to the product accountability tank - the process MBA. Consider an MBA comprising the chop-leach cell, with an inward flow consisting of the intact spent-fuel assemblies and outward flows consisting of leached hulls and dissolver solution. Given knowledge of the original uranium mass in the fuel and a measurement of the uranium-plutonium concentration ratio in the dissolver solution, the gravimetric method can be used to determine the amount of plutonium in the spent-fuel assemblies. A measurement of residual plutonium in the leached hulls would then permit the determination of a plutonium material balance for the chop-leach cell alone, since the volumetrically determined plutonium in the input accountability tank yields the plutonium in the flow leaving the chop-leach cell for the process MBA. The uncertainty in the balance can be estimated given the individual measurement uncertainties

The potential of continuous, local atomic clock measurements for earthquake prediction and volcanology

Directory of Open Access Journals (Sweden)

Bondarescu Mihai

2015-01-01

Full Text Available Modern optical atomic clocks along with the optical fiber technology currently being developed can measure the geoid, which is the equipotential surface that extends the mean sea level on continents, to a precision that competes with existing technology. In this proceeding, we point out that atomic clocks have the potential to not only map the sea level surface on continents, but also look at variations of the geoid as a function of time with unprecedented timing resolution. The local time series of the geoid has a plethora of applications. These include potential improvement in the predictions of earthquakes and volcanoes, and closer monitoring of ground uplift in areas where hydraulic fracturing is performed.

Mathematical modelling of the sorption isotherms of quince

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Mitrevski Vangelce

2017-01-01

Full Text Available The moisture adsorption isotherms of quince were determined at four temperatures 15, 30, 45, and 60°C over a range of water activity from 0.110 to 0.920 using the standard static gravimetric method. The experimental data were fitted with generated three parameter sorption isotherm models on Mitrevski et al., and the referent Anderson model known in the scientific and engineering literature as Guggenheim- Anderson-de Boer model. In order to find which models give the best results, large number of numerical experiments was performed. After that, several statistical criteria for estimation and selection of the best sorption isotherm model was used. The performed statistical analysis shows that the generated three parameter model M11 gave the best fit to the sorption data of quince than the referent three parameter Anderson model.

Ore prospecting in the Iberian Pyrite Belt using seismic and potential-field data

International Nuclear Information System (INIS)

Carvalho, João; Pinto, Carlos; Sousa, Pedro; Matos, João Xavier

2011-01-01

Ore prospecting using gravimetric and magnetic data has become one of the traditional approaches used in past decades, often complemented with electric and electromagnetic methods. However, due to the problem of non-uniqueness inherent to potential-field modelling, constraints provided by structural methods such as seismic reflection are often used. During the exploration of polymetallic massive sulfide minerals in the Iberian Pyrite Belt, Figueira de Cavaleiros sector, located in the Sado Tertiary Basin, several gravimetric and magnetic anomalies were considered to be interesting targets. In order to reduce any ambiguity in the gravimetric modelling and to confirm the geological model of the area, two seismic reflection profiles were acquired. The interpretation of these profiles was assisted by three mechanical boreholes, two of which were located in the research area to make a seismostratigraphic interpretation. Unfortunately, the gravimetric modelling suggests that the anomaly has a lithological and structural origin and is not related to massive sulfides. Nevertheless, a good agreement between the seismic and potential-field data was achieved and new insights into the geological model for the region were obtained from this work, with accurate data about the Tertiary cover and Palaeozoic basement

Feasibility of Using an Electrolysis Cell for Quantification of the Electrolytic Products of Water from Gravimetric Measurement.

Science.gov (United States)

Melaku, Samuel; Gebeyehu, Zewdu; Dabke, Rajeev B

2018-01-01

A gravimetric method for the quantitative assessment of the products of electrolysis of water is presented. In this approach, the electrolysis cell was directly powered by 9 V batteries. Prior to electrolysis, a known amount of potassium hydrogen phthalate (KHP) was added to the cathode compartment, and an excess amount of KHCO 3 was added to the anode compartment electrolyte. During electrolysis, cathode and anode compartments produced OH - (aq) and H + (aq) ions, respectively. Electrolytically produced OH - (aq) neutralized the KHP, and the completion of this neutralization was detected by a visual indicator color change. Electrolytically produced H + (aq) reacted with HCO 3 - (aq) liberating CO 2 (g) from the anode compartment. Concurrent liberation of H 2 (g) and O 2 (g) at the cathode and anode, respectively, resulted in a decrease in the mass of the cell. Mass of the electrolysis cell was monitored. Liberation of CO 2 (g) resulted in a pronounced effect of a decrease in mass. Experimentally determined decrease in mass (53.7 g/Faraday) agreed with that predicted from Faraday's laws of electrolysis (53.0 g/Faraday). The efficacy of the cell was tested to quantify the acid content in household vinegar samples. Accurate results were obtained for vinegar analysis with a precision better than 5% in most cases. The cell offers the advantages of coulometric method and additionally simplifies the circuitry by eliminating the use of a constant current power source or a coulometer.

Un modelo geodésico para Colombia

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Sánchez Rodríguez Laura Marlene

1995-10-01

Full Text Available

The processed gravimetric information is compiled in the SIMPLE BOUGUER GRAVITY ANOMALY MAP OF COLOMBIA, EASTERN PANAMA AND ADYACENT MARINE AREAS, published in 1989 by The Geological Society of America Inc. Based on Isostatic anomaly values (approximated obtained for difference between the observed Simple Bouguer anomaly values and itself, processed by means of the Bidimensional Fourier Transform, the Physical-Mathematical Stokes model was applied. With this model can be possible to determine the geoid undulations, relating the normal gravity, the anomaly potential and the gravity anomalies; these undulations are based on the WGS-84 ellipsoid.

La información gravimétrica procesada esta compilada en el Mapa de anomalía Bouguer simple de Colombia, este de Panamá y aéreas marinas adyacentes, publicado por “The Geological Society of America Inc.” en 1989. A partir de los valores de la anomalía isostática (aproximada, resultante de la diferencia entre la anomalía Bouguer simple observada y la misma, procesada por medio de la Transformada de Fourier Bidimensional, se aplicó el modelo físico-matemático de Stokes, con el cual se determinan las ondulaciones geoidales relacionando la gravedad normal, el potencial anómalo y las anomalías de la gravedad; tales ondulaciones se referenciaron al elipsoide WGS-84.

Testing EGM2008 on Leveling Data from Scandinavia, Adjacent Baltic Areas, and Greenland

DEFF Research Database (Denmark)

Strykowski, Gabriel; Forsberg, René

2010-01-01

We tested EGM2008 on GPS/leveling data from Scandinavia and adjacent areas. EGM2008 performs at the same level as the best regional geoid model, NKG2004. However, the direct evaluation of EGM2008 is difficult in Greenland because no leveling data are available. Nevertheless, we show on 78 GPS-MSS...

Aerosols concentration in the Candiota area applying different gravimetric methods of sampling and numeric modelling.

Science.gov (United States)

Braga, C F; Alves, R C M; Teixeira, E C; Pire, M

2002-12-01

The main purpose of the present work is to study the concentration of atmospheric particles in the Candiota region, in the state of Rio Grande do Sul, where the Presidente Médici coal power plant is located. Aerosol samples were collected at the studied locations between December 2000 and December 2001 during 24 h periods at 15 day intervals using HV PM10 and dichotomous samplers. Then, the values obtained with the ISCST (Industrial Source Complex Term) model, with the HV PM10 sampler at all studied stations, and with the dichotomous sampler at the 8 de Agosto station were compared with each other. The results show that the values for the model had been underestimated in relation to the HV PM10 data for the studied stations, but agreed with the values obtained with the dichotomous sampler.

Dsm Extraction and Evaluation from GEOEYE-1 Stereo Imagery

Science.gov (United States)

Saldaña, M. M.; Aguilar, M. A.; Aguilar, F. J.; Fernández, I.

2012-07-01

The newest very high resolution (VHR) commercial satellites, such as GeoEye-1 or WorldView-2, open new possibilities for cartographic applications, orthoimages generation and extraction of Digital Surface Models (DSMs). These DSMs are generated by image matching strategies from VHR satellite stereopairs imagery, reconstructing the 3D surface corresponding to the first surface view of the earth containing both microrelief (buildings, trees and so on) and bare terrain. The main aim of this work is to carry out an accuracy assessment test on the DSMs extracted from a GeoEye-1 stereopair captured in August 2011. A LiDAR derived DSM taken at the same month that the satellite imagery was used as ground truth. The influence of factors such as number of Ground Control Points (GCPs), sensor models tested and the geoid employed to transform the ellipsoid to orthometric heights were going to be evaluated. In this way, different sets of GCPs ranging from 7 to 45, two sensor models and two geoids (EGM96 and EGM08, the last adapted for Spain vertical network by the Spanish's National Geographic Institute) were tested in this work. The photogrammetric software package used was OrthoEngine from PCI Geomatica v. 10.3.2. OrthoEngine implements both sensor models tested: (i) the physical model developed by Toutin (CCRS) and, (ii) the rational function model using rational polynomial coefficients supplied by the vendor and later refined by means of the zero order linear functions (RPC0). When high accurate and well-distributed GCPs were used, the planimetric and vertical accuracies of DSMs generated from the GeoEye-1 Geo stereopair were always better than 0.5 m. Using only 7 GCPs and RPC0, a vertical accuracy around 0.43 m measured as standard deviation was attained. The geoid used by OrthoEngine (EGM96) produced similar results that the EGM08 adapted for Spain vertical network.

Determining the better solvent and time for extracting soil by soxhlet in TPH (Total Petroleum Hydrocarbon) gravimetric method; A determinacao de qual o melhor solvente e o melhor tempo de extracao de sedimento em aparato Soxhlet na metodologia do TPH (Total Petroleum Hydrocarbon) gravimetrico

Energy Technology Data Exchange (ETDEWEB)

Koike, Renato S.; Lima, Guilherme; Baisch, Paulo R. [Fundacao Universidade Federal do Rio Grande (FURG), RS (Brazil)

2004-07-01

There are several methods of TPH (Total Petroleum Hydrocarbons) analysis of petroleum hydrocarbons contaminants in sediment. The TPH gravimetric has been widely used in many studies and in oil spill monitoring case. The present work examined three different solvents (DCM, DCM/N-HEX and N-HEX), in three different times, to the purpose to optimize the contaminants extraction using USEPA 9071 and 3540 reference method. Then was realized analysis of Total Organic Carbon (TOC) for monitoring the reproducible extracts. The sediments used in this experiment was collected in the Cavalos Island, localized in the city of Rio Grande, RS-Brasil. The sediment was 'washed' and after then contaminated with petroleum. The extracts were realized in Soxhlet apparatus, in three different times (4, 8 and 12 hours), and TOC analysis were realized before and after the extraction. The result demonstrated that eight hours with DCM/N-HEX solvent is more indicated for TPH gravimetric in sediment analysis with high concentration of petroleum hydrocarbons. TOC analysis demonstrated inappropriate for monitoring extract reproducibility. (author)

Inversion of Solid Earth's Varying Shape 2: Using Self-Consistency to Infer Static Ocean Topography

Science.gov (United States)

Blewitt, G.; Clarke, P. J.

2002-12-01

We have developed a spectral approach to invert for the redistribution of mass on the Earth's surface given precise global geodetic measurements of the solid Earth's geometrical shape. We used the elastic load Love number formalism to characterize the redistributed mass as a spherical harmonic expansion, truncated at some degree and order n. [Clarke and Blewitt, this meeting]. Here we incorporate the additional physical constraint that the sea surface in hydrostatic equilibrium corresponds to an equipotential surface, to infer the non-steric component of static ocean topography. Our model rigorously accounts for self-gravitation of the ocean, continental surface mass, and the deformed solid Earth, such that the sea surface adopts a new equipotential surface consistent with ocean-land mass exchange, deformation of the geoid, deformation of the sea floor, and the geographical configuration of the oceans and continents. We develop a self-consistent spectral inversion method to solve for the distribution of continental surface mass that would generate geographic variations in relative mean sea level such that the total (ocean plus continental) mass distribution agrees with the original geodetic estimates to degree and order n. We apply this theory to study the contribution of seasonal inter-hemispheric (degree-1) mass transfer to seasonal variation in static ocean topography, using a published empirical seasonal model for degree-1 surface loading derived using GPS coordinate time series from the global IGS network [Blewitt et al., Science 294, 2,342-2,345, 2001]. The resulting predictions of seasonal variations of relative sea level strongly depend on location, with peak variations ranging from 3 mm to 19 mm. The largest peak variations are predicted in mid-August around Antarctica and the southern hemisphere in general; the lowest variations are predicted in the northern hemisphere. Corresponding maximum continental loading occurs in Canada and Siberia at the water

Recent developments in high-resolution global altimetric gravity field modeling

DEFF Research Database (Denmark)

Andersen, Ole Baltazar; Knudsen, Per; Berry, P. A .M.

2010-01-01

older gravity fields show accuracy improvement of the order of 20-40% due to a combination of retracking, enhanced processing, and the use of the new EGM2008 geoid model. In coastal and polar regions, accuracy improved in many places by 40-50% (or more) compared with older global marine gravity fields.......In recent years, dedicated effort has been made to improve high-resolution global marine gravity fields. One new global field is the Danish National Space Center (DNSC) 1-minute grid called DNSC08GRA, released in 2008. DNSC08GRA was derived from double-retracked satellite altimetry, mainly from...... the ERS-1 geodetic mission data, augmented with new retracked GEOSAT data which have significantly enhanced the range and hence the gravity field accuracy. DNSC08GRA is the first high-resolution global gravity field to cover the entire Arctic Ocean all the way to the North Pole. Comparisons with other...

Monterey Bay Geoid

Science.gov (United States)

1994-03-01

thought to be a flat disk. The first scientific hypothesis that the earth was spherical is credited to Thales of Milet in 600 B.C. or Pythagoras in 550...acceleration can be integrated over the surface, by Gauss’s theorem and gives: 35 v1 Wv2 <v3 Figure 12. Equipotential Surfaces and Gravity: V,, V2, V3 are...continuous derivatives where they satisfy Laplace’s equation. Stokes’ theorem states that a harmonic function outside a surface is uniquely determined by

Comparison of invasive and non-invasive electromagnetic methods in soil water content estimation of a dike model

International Nuclear Information System (INIS)

Preko, Kwasi; Scheuermann, Alexander; Wilhelm, Helmut

2009-01-01

Water infiltration through a dike model under controlled flooding and drainage conditions was investigated using the gravimetric soil water sampling technique and electromagnetic techniques, in particular ground penetrating radar (GPR) applied in different forms, time domain reflectometry with intelligent microelements (TRIME-TDR) and spatial-time domain reflectometry (S-TDR). The experiments were conducted on the model in two phases. In the first phase, the model was flooded with varying water levels between 0 and 1.25 m above the waterproof base of the model. In the second phase, the characteristics of the temporal water content changes were investigated over a period of 65 days as the flood water drained off from the 1.25 m level. The dike model was constructed with soil of the texture class loamy sand. The aim of the experiment was to investigate whether GPR-based invasive and non-invasive methods were able to quantitatively observe and correctly monitor temporal changes in the volumetric water content (VWC) within embankment dams. The VWC values from the various techniques corresponded very well, especially with low VWC values. A comparison with the VWC of gravimetric soil water sampling showed a satisfactory reproducibility. Characteristic discrepancies were recorded with higher values of the VWC. Under saturated conditions only the invasive methods were able to produce reasonable values of the VWC. After the release of the highest flood level, the drainage phase could be characterized by two invasive methods based on the TDR and GPR techniques

Gravimetric structure for the abyssal mantle massif of Saint Peter and Saint Paul peridotite ridge, Equatorial Atlantic Ocean, and its relation to active uplift

Directory of Open Access Journals (Sweden)

KENJI F. MOTOKI

2014-06-01

Full Text Available This paper presents gravimetric and morphologic analyses based on the satellite-derived data set of EGM2008 and TOPEX for the area of the oceanic mantle massif of the Saint Peter and Saint Paul peridotite ridge, Equatorial Atlantic Ocean. The free-air anomaly indicates that the present plate boundary is not situated along the longitudinal graben which cuts peridotite ridge, but about 20 km to the north of it. The high Bouguer anomaly of the peridotite ridge suggests that it is constituted mainly by unserpentinised ultramafic rocks. The absence of isostatic compensation and low-degree serpentinisation of the ultramafic rocks indicate that the peridotite ridge is sustained mainly by active tectonic uplift. The unparallel relation between the transform fault and the relative plate motion generates near north-south compression and the consequent tectonic uplift. In this sense, the peridotite massif is a pressure ridge due to the strike-slip displacement of the Saint Paul Transform Fault.

Pyrolysis characteristics and kinetic parameters determination of biomass fuel powders by differential thermal gravimetric analysis (TGA/DTG)

International Nuclear Information System (INIS)

El-Sayed, Saad A.; Mostafa, M.E.

2014-01-01

Highlights: • The sugarcane bagasse powder has better energy value compared to the cotton stalks. • Bagasse moisture is entrained in its cell walls and its evaporation needs more energy. • The cotton stalks is more reactive and readily combustible than the bagasse powders. • A lower E and A 0 has been found for bagasse compared with cotton stalks powders. • Calculated E of bagasse and cotton stalks by direct and integral methods are different. - Abstract: The kinetics of the thermal decomposition of the two biomass materials (sugarcane bagasse and cotton stalks powders) were evaluated using a differential thermo-gravimetric analyzer under a non-isothermal condition. Two distinct reaction zones were observed for the two biomasses. The direct Arrhenius plot method and the integral method were applied for determination of kinetic parameters: activation energy, pre-exponential factor, and order of reaction. The weight loss curve showed that pyrolysis of sugarcane bagasse and cotton stalks took place mainly in the range of 200–500 °C. The activation energy of the sugarcane bagasse powder obtained by the direct Arrhenius plot method ranged between 43 and 53.5 kJ/mol. On the other side, the integral method shows larger values of activation energy (77–87.7 kJ/mol). The activation energy of the cotton stalks powder obtained by the direct Arrhenius plot method was ranged between 98.5 and 100.2 kJ/mol, but the integral method shows larger values of activation energy (72.5–127.8 kJ/mol)

Gravimetrical and chemical characterization of SiOx structures deposited on fine powders by short plasma exposure in a plasma down stream reactor

International Nuclear Information System (INIS)

Spillmann, Adrian; Sonnenfeld, Axel; Rohr, Philipp Rudolf von

2008-01-01

The surface of lactose particles was modified by a plasma-enhanced chemical vapor deposition process to improve the flow behavior of the powder. For this, the particulates were treated in a plasma down stream reactor which provides a short (50 ms) and homogeneous exposure to the capacitively coupled RF discharge. The organosilicon monomer hexamethyldisiloxane (HMDSO) was used as a precursor for the formation of SiO x which is deposited on the substrate particle surface. For varying process gas mixtures (O 2 /Ar/HMDSO) and RF power applied, the amount of the deposited material was determined gravimetrically after dissolution of the lactose substrate particles and the chemical composition of the accumulated deposition material was investigated by means of attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. The concentration of the deposited SiO x relating to the substrate material was found to be in the range of 0.1 wt.%. Based on the ATR-FTIR analysis, the inorganic, i.e. oxidic SiO x fraction of the obtained deposits was shown to be controllable by varying the process parameters, whilst a relatively large amount of organic structures must be considered.

Importance of dynamic topography in Himalaya-Tibetan plateau region

Science.gov (United States)

Ghosh, A.; Singh, S.

2017-12-01

Himalaya-Tibetan plateau region has the highest topography in the world. Various studies have been done to understand the mechanisms responsible for sustaining this high topography. However, the existence of dynamic topography in this region is still uncertain, though there have been some studies exploring the role of channel flow in lower crust leading to some topography. We investigated the role of radial mantle flow in this region by studying the relationship between geoid and topography. High geoid-to-topography ratios (GTR) were observed along the Himalayas suggesting deeper compensation mechanisms. However, further north, the geoid and topography relationship became a lot more complex as high as well as low GTR values were observed. The high GTR regions also coincided with area of high filtered free air gravity anomalies, indicating dynamic support. We also looked at the spectral components of gravity, geoid and topography, and calculated response functions to distinguish between different compensation mechanisms. We estimated the average elastic thickness of the whole region to be around 40 km from coherence and admittance studies. The GTR and admittance-coherence studies suggest deeper mass anomalies playing a role in supporting the topography along Himalayas and the area between Altyn Tagh and Kunlun faults.

Evaluation of the geopotential value W0LVD of China

Directory of Open Access Journals (Sweden)

Lin He

2017-11-01

Full Text Available Estimation of the zero-height geopotential value W0LVD for the CVD (China Vertical Datum plays a fundamental role in the connection of traditional height reference systems into a global height system. Estimation the W0LVD of China is based on the computation of the mean geopotential offset between the value W0 = 62636856.0 m2s−2, selected as reference in this study, and the unknown geopotential value W0LVD. This estimation is based on the combination of ellipsoidal heights, levelled heights (referring to the CVD, and some physical parameters, such as geopotential values, gravity values, and geoid undulations. The geoid undulations derived from the GGM (Global Geopotential Models. This combination is performed through three approaches: The first one is based on the theory of Molodensky, and the second one compares levelled heights and geopotential values derived from the GGMs, while the third one analyses the differences between GPS/Levelling and GGMs geoid undulations. The approaches are evaluated at 65 benchmarks (BMs covered around Qingdao where the tide gauge is used to observe the local mean sea level of China. The results from three approaches are very similar. Furthermore, the W0LVD determined for the China local vertical datum was 62636852.9462 m2s−2, indicates a bias of about 3.0538 m2/s−2 compared to the conventional value of 62636856.0 m2s−2.

Uncertainty associated with the gravimetric measurement of particulate matter concentration in ambient air.

Science.gov (United States)

Lacey, Ronald E; Faulkner, William Brock

2015-07-01

This work applied a propagation of uncertainty method to typical total suspended particulate (TSP) sampling apparatus in order to estimate the overall measurement uncertainty. The objectives of this study were to estimate the uncertainty for three TSP samplers, develop an uncertainty budget, and determine the sensitivity of the total uncertainty to environmental parameters. The samplers evaluated were the TAMU High Volume TSP Sampler at a nominal volumetric flow rate of 1.42 m3 min(-1) (50 CFM), the TAMU Low Volume TSP Sampler at a nominal volumetric flow rate of 17 L min(-1) (0.6 CFM) and the EPA TSP Sampler at the nominal volumetric flow rates of 1.1 and 1.7 m3 min(-1) (39 and 60 CFM). Under nominal operating conditions the overall measurement uncertainty was found to vary from 6.1x10(-6) g m(-3) to 18.0x10(-6) g m(-3), which represented an uncertainty of 1.7% to 5.2% of the measurement. Analysis of the uncertainty budget determined that three of the instrument parameters contributed significantly to the overall uncertainty: the uncertainty in the pressure drop measurement across the orifice meter during both calibration and testing and the uncertainty of the airflow standard used during calibration of the orifice meter. Five environmental parameters occurring during field measurements were considered for their effect on overall uncertainty: ambient TSP concentration, volumetric airflow rate, ambient temperature, ambient pressure, and ambient relative humidity. Of these, only ambient TSP concentration and volumetric airflow rate were found to have a strong effect on the overall uncertainty. The technique described in this paper can be applied to other measurement systems and is especially useful where there are no methods available to generate these values empirically. This work addresses measurement uncertainty of TSP samplers used in ambient conditions. Estimation of uncertainty in gravimetric measurements is of particular interest, since as ambient particulate

Thermal treatment investigation of natural lizardite at the atmospheric pressure, based on XRD and differential thermal analysis/thermal gravimetric analysis methods

International Nuclear Information System (INIS)

Dabiri, R.; Karimi Shahraki, B.; Mollaei, H.; Ghaffari, M.

2009-01-01

Determination of stability limits, mineralogical changes and thermal reaction of serpentine minerals are very important for the investigation of magmatism, mechanism and depth of plates of subduction. During the subduction process, serpentine (Lizardite) minerals will release their water due to thermal reactions. This dehydration can play an important role in volcanism processes related to the subduction, In this study, serpentine minerals (Lizardite) collected from the Neyriz Ophiolite Complex were dehydrated under the constant atmospheric pressure. These mineralogical changes were determined by X-Ray diffraction and differential thermal analysis-thermal gravimetric analyses methods. This study shows natural lizardites that heated for about one hour is stable up to 550 d eg C . Dehydration reactions on lizardite started at approximately between 100 to 150 d eg C and dehydroxylation reactions started at approximately 550-690 d eg C . As a result of thermal reaction, the decomposition of lizardite will take place and then changes in to olivine (forsterite). Crystallization of olivine (forsterite) will start at 600 d eg C . This mineral is stable up to 700 d eg C and then crystallization of enstatite will start at 700 d eg C . During this dehydration and crystallization reaction, amorphous processes will start at 600 d eg C and some amount water and silica will release.

Gravity derived depth to basement in Santiago Basin, Chile: implications for its geological evolution, hydrogeology, low enthalpy geothermal, soil characterization and geo-hazards

OpenAIRE

Yáñez, Gonzalo; Muñoz, Mauricio; Flores-Aqueveque, Valentina; Bosch, Andrés

2015-01-01

A recording of 1,115 gravimetric stations, the review of 368 wells, and the petrophysics measurements of 106 samples from representative outcrops have been used for a comprehensive geological/geophysical study of Santiago Basin. 2.5D and 3D gravimetric modeling, constrained by regional geology, soil and bedrock densities, edge-basin outcrops, depth (minimum) to basement from wells, and detailed modeling of heterogeneous bedrock and midcrustal blocks, provided a well-constrained depth to basem...

Blood Density Is Nearly Equal to Water Density: A Validation Study of the Gravimetric Method of Measuring Intraoperative Blood Loss.

Science.gov (United States)

Vitello, Dominic J; Ripper, Richard M; Fettiplace, Michael R; Weinberg, Guy L; Vitello, Joseph M

2015-01-01

Purpose. The gravimetric method of weighing surgical sponges is used to quantify intraoperative blood loss. The dry mass minus the wet mass of the gauze equals the volume of blood lost. This method assumes that the density of blood is equivalent to water (1 gm/mL). This study's purpose was to validate the assumption that the density of blood is equivalent to water and to correlate density with hematocrit. Methods. 50 µL of whole blood was weighed from eighteen rats. A distilled water control was weighed for each blood sample. The averages of the blood and water were compared utilizing a Student's unpaired, one-tailed t-test. The masses of the blood samples and the hematocrits were compared using a linear regression. Results. The average mass of the eighteen blood samples was 0.0489 g and that of the distilled water controls was 0.0492 g. The t-test showed P = 0.2269 and R (2) = 0.03154. The hematocrit values ranged from 24% to 48%. The linear regression R (2) value was 0.1767. Conclusions. The R (2) value comparing the blood and distilled water masses suggests high correlation between the two populations. Linear regression showed the hematocrit was not proportional to the mass of the blood. The study confirmed that the measured density of blood is similar to water.

Advances and Best Practices in Airborne Gravimetry from the U.S. GRAV-D Project

Science.gov (United States)

Diehl, Theresa; Childers, Vicki; Preaux, Sandra; Holmes, Simon; Weil, Carly

2013-04-01

The Gravity for the Redefinition of the American Vertical Datum (GRAV-D) project, an official policy of the U.S. National Geodetic Survey as of 2007, is working to survey the entire U.S. and its holdings with high-altitude airborne gravimetry. The goal of the project is to provide a consistent, high-quality gravity dataset that will become the cornerstone of a new gravimetric geoid and national vertical datum in 2022. Over the last five years, the GRAV-D project has surveyed more than 25% of the country, accomplishing almost 500 flights on six different aircraft platforms and producing more than 3.7 Million square km of data thus far. This wealth of experience has led to advances in the collection, processing, and evaluation of high-altitude (20,000 - 35,000 ft) airborne gravity data. This presentation will highlight the most important practical and theoretical advances of the GRAV-D project, giving an introduction to each. Examples of innovation include: 1. Use of navigation grade inertial measurement unit data and precise lever arm measurements for positioning; 2. New quality control tests and software for near real-time analysis of data in the field; 3. Increased accuracy of gravity post-processing by reexamining assumptions and simplifications that were inconsistent with a goal of 1 mGal precision; and 4. Better final data evaluation through crossovers, additional statistics, and inclusion of airborne data into harmonic models that use EGM08 as a base model. The increases in data quality that resulted from implementation of the above advances (and others) will be shown with a case study of the GRAV-D 2008 southern Alaska survey near Anchorage, over Cook Inlet. The case study's statistics and comparisons to global models illustrate the impact that these advances have had on the final airborne gravity data quality. Finally, the presentation will summarize the best practices identified by the project from its last five years of experience.

Evaluation of gravity field model EIGEN-6C4 by means of various functions of gravity potential, and by GNSS/levelling

Directory of Open Access Journals (Sweden)

Jan Kostelecký

2015-06-01

Full Text Available The combined gravity field model EIGEN-6C4 (Förste et al., 2014 is the latest combined global gravity field model of GFZ Potsdam and GRGS Toulouse. EIGEN-6C4 has been generated including the satellite gravity gradiometry data of the entire GOCE mission (November 2009 till October 2013 and is of maximum spherical degree and order 2190. In this study EIGEN-6C4 has been compared with EGM2008 to its maximum degree and order via gravity disturbances and Tzz part of the Marussi tensor of the second derivatives of the disturbing potential. The emphasis is put on such areas where GOCE data (complete set of gradiometry measurements after reductions in EIGEN-6C4 obviously contributes to an improvement of the gravity field description. GNSS/levelling geoid heights are independent data source for the evaluation of gravity field models. Therefore, we use the GNSS/levelling data sets over the territories of Europe, Czech Republic and Slovakia for the evaluation of EIGEN-6C4 w.r.t. EGM2008.

Gravity Field Parameter Estimation Using QR Factorization

Science.gov (United States)

Klokocnik, J.; Wagner, C. A.; McAdoo, D.; Kostelecky, J.; Bezdek, A.; Novak, P.; Gruber, C.; Marty, J.; Bruinsma, S. L.; Gratton, S.; Balmino, G.; Baboulin, M.

2007-12-01

This study compares the accuracy of the estimated geopotential coefficients when QR factorization is used instead of the classical method applied at our institute, namely the generation of normal equations that are solved by means of Cholesky decomposition. The objective is to evaluate the gain in numerical precision, which is obtained at considerable extra cost in terms of computer resources. Therefore, a significant increase in precision must be realized in order to justify the additional cost. Numerical simulations were done in order to examine the performance of both solution methods. Reference gravity gradients were simulated, using the EIGEN-GL04C gravity field model to degree and order 300, every 3 seconds along a near-circular, polar orbit at 250 km altitude. The simulation spanned a total of 60 days. A polar orbit was selected in this simulation in order to avoid the 'polar gap' problem, which causes inaccurate estimation of the low-order spherical harmonic coefficients. Regularization is required in that case (e.g., the GOCE mission), which is not the subject of the present study. The simulated gravity gradients, to which white noise was added, were then processed with the GINS software package, applying EIGEN-CG03 as the background gravity field model, followed either by the usual normal equation computation or using the QR approach for incremental linear least squares. The accuracy assessment of the gravity field recovery consists in computing the median error degree-variance spectra, accumulated geoid errors, geoid errors due to individual coefficients, and geoid errors calculated on a global grid. The performance, in terms of memory usage, required disk space, and CPU time, of the QR versus the normal equation approach is also evaluated.

MEASUREMENT AND MODELLING OF SORPTION EQUILIBRIUM CURVE OF WATER ON PA6, PP, HDPE AND PVC BY USING FLORY-HUGGINS MODEL

Directory of Open Access Journals (Sweden)

Suherman Suherman

2012-02-01

Full Text Available The sorption of water on granular polyamide-6 (PA6, granular polypropylene (PP, and powdery high density polyethylene (HDPE and powdery polyvinyl chloride (PVC were measured using a gravimetric method in a magnetic suspension balance (MSB. The Flory-Huggins model was successfully applied on the sorption equilibrium curve of all investigated polymers. The influence of temperature is low. The value of Flory-Huggins parameters(c of PA6, PVC, PP and HDPE were 1.8, 5.8, 6.3, and 8.1, respectively. The water in PA6 is mainly bound moisture, while in PP, HDPE and PVC it is mainly surface moisture.

Analiza tačnosti visina bosanskohercegovačke trigonometrijske mreže pomoću GPS/EGM podataka : Accuracy analyses of B&H trigonometric network heights by GPS/EGM data

Directory of Open Access Journals (Sweden)

Medžida Mulić

2012-06-01

Full Text Available Dostupnost savremenih globalnih geoidnih modela kao i 3D koordinata u globalnom koordinatnom referentnom sistemu omogućava anlazu tačnosti ortometrijskih visina trionometrijske mreže. Rad pokazuje preliminarne rezultate analize tačnosti visina trigonometrijske mreže u Bosni i Hercegovini, a na osnovu usporedbe visina izračunatih korištenjem GPS visina i EGM geoidnih modela. Preliminarni rezultati ukazuju na postojanje grubih pogrešaka u visinama trigonometrijskih tačaka BiH trigonometrijske mreže. : Analysis of the accuracy of the orthometric heights of the old trigonometric points are posible since the global accurate models of geoid as well as 3D coordinates in the global coordinate system became available. Preliminary results of the heights accuracy analyze in the old trigonometric network in the in Bosnia and Herzegovina are shown in this paper. The analyze has done by comparing the orthometric heights calculated using by GPS height and the modern global geoid models EGM, with the old official heights of trigonometric points. The results indicate the existence of blunders among the heights in the old trigonometric network of Bosnia and Herzegovina.

Sea level rise and the geoid: factor analysis approach

Directory of Open Access Journals (Sweden)

Alexey Sadovski

2013-08-01

Full Text Available Sea levels are rising around the world, and this is a particular concern along most of the coasts of the United States. A 1989 EPA report shows that sea levels rose 5-6 inches more than the global average along the Mid-Atlantic and Gulf Coasts in the last century. The main reason for this is coastal land subsidence. This sea level rise is considered more as relative sea level rise than global sea level rise. Thus, instead of studying sea level rise globally, this paper describes a statistical approach by using factor analysis of regional sea level rates of change. Unlike physical models and semi-empirical models that attempt to approach how much and how fast sea levels are changing, this methodology allows for a discussion of the factor(s that statistically affects sea level rates of change, and seeks patterns to explain spatial correlations.

Optimally combined regional geoid models for the realization of height systems in developing countries - ORG4heights

Science.gov (United States)

Lieb, Verena; Schmidt, Michael; Willberg, Martin; Pail, Roland

2017-04-01

Precise height systems require high-resolution and high-quality gravity data. However, such data sets are sparse especially in developing or newly industrializing countries. Thus, we initiated the DFG-project "ORG4heights" for the formulation of a general scientific concept how to (1) optimally combine all available data sets and (2) estimate realistic errors. The resulting regional gravity field models then deliver the fundamental basis for (3) establishing physical national height systems. The innovative key aspects of the project incorporate the development of a method which links (low- up to mid-resolution) gravity satellite mission data and (high- down to low-quality) terrestrial data. Hereby, an optimal combination of the data utilizing their highest measure of information including uncertainty quantification and analyzing systematic omission errors is pursued. Regional gravity field modeling via Multi-Resolution Representation (MRR) and Least Squares Collocation (LSC) are studied in detail and compared based on their theoretical fundamentals. From the findings, MRR shall be further developed towards implementing a pyramid algorithm. Within the project, we investigate comprehensive case studies in Saudi Arabia and South America, i. e. regions with varying topography, by means of simulated data with heterogeneous distribution, resolution, quality and altitude. GPS and tide gauge records serve as complementary input or validation data. The resulting products include error propagation, internal and external validation. A generalized concept then is derived in order to establish physical height systems in developing countries. The recommendations may serve as guidelines for sciences and administration. We present the ideas and strategies of the project, which combines methodical development and practical applications with high socio-economic impact.

A new approach to the unrest and subsequent eruption at El Hierro Island (2011) based on petrological, seismological, geodetical and gravimetric data

Science.gov (United States)

Meletlidis, Stavros; Di Roberto, Alessio; Domínguez Cerdeña, Itahiza; Pompilio, Massimo; García-Cañada, Laura; Bertagnini, Antonella; Benito Saz, Maria Angeles; Del Carlo, Paola; Sainz-Maza Aparicio, Sergio; Lopez Moreno, Carmen; Moure García, David

2014-05-01

A shallow submarine eruption took place on 10th October 2011, about 1.8 km off the coast of La Restinga, a small village located in El Hierro (Canary Islands, Spain). The eruption lasted for about four months and ended by early March 2012. The eruption was preceded by an unrest episode that initiated about three months before, in July 2011, and characterized by more than 10,000 localized earthquakes accompanied by up to 5 cm of vertical ground deformation. In the Canary Islands, this event represents the first case of an eruption that was monitored since the unrest to the end by the monitoring network of IGN (Instituto Geográfico National), providing a huge dataset that includes geophysical (seismic, magnetic and gravimetric), geodetic, geochemistry and petrological data. In this work we use the seismic, GPS and gravity records collected by IGN along with the petrological data derived from the study of various lava balloons, scoriaceous fragments and ash.Geophysical and geochemical monitoring tools provide a variety of information that need to be interpreted in terms of magma movement and/or interaction of magma with host rocks. We present a model, based on this data, which describes the intrusion and ascent of the magma. According to this model, a major intrusion beneath and around preexisting high-density magmatic bodies, localized in the central sector of the island, led to an eruption in the Southern sector of the island. After a failed attempt to reach the surface, while various dykes were emplaced, through a low fractured area in the Central and Northern parts of the island, the ascending magma finally found its way in the submarine area of La Restinga, in the South rift zone, at a depth of 350 m below sea level. Feeding of the eruption was achieved by the ascension of an important volume of material from the upper mantle which was emplaced near the crust-mantle boundary. However, the very energetic post-eruptive unrests - we had five episodes up today with

The effect of copper, MDA, and accelerated aging on jet fuel thermal stability as measured by the gravimetric JFTOT

Energy Technology Data Exchange (ETDEWEB)

Pande, S.G. [Geo-Centers, Inc., Ft. Washington, MD (United States); Hardy, D.R. [Navy Technology Center for Safety and Survivability, Washington, DC (United States)

1995-05-01

Thermally unstable jet fuels pose operational problems. In order to adequately identify such fuels, factors that realistically impact on thermal stability were examined. Evaluation was based on a quantitative method of measuring thermal stability, viz., NRL`s recently developed gravimetric JFTOT. This method gives a quantitative measurement of both the strip deposit and filterables formed. The pertinent factors examined, included the individual and interactive effects of: soluble copper, MDA (metal deactivator), and aging. The latter was accelerated to simulate field conditions of approximately six months aging at ambient temperature and pressure. The results indicate that the individual and interactive effects of copper, MDA, and accelerated aging appear to be fuel dependent. Based on the results, the three test fuels examined (one JP-8 and two JP-5s) were categorized as exhibiting very good, typical, and poor thermal stabilities, respectively. For both the very good and poor thermal stability fuels, the effect of copper in conjunction with accelerated aging did not significantly increase the total thermal deposits of the neat fuels. In contrast, for the typical thermal stability fuel, the combined effects of copper and accelerated aging, did. Furthermore, the addition of MDA prior to aging of the copper-doped, typical stability fuel significantly counteracted the adverse effect of copper and aging. A similar beneficial effect of MDA was not observed for the poor stability fuel. These results focus on the compositional differences among fuels and the need to elucidate these differences (physical and chemical) for a better understanding and prediction of their performance.

Geometrical and gravimetrical observations of the Aral Sea and its tributaries along with hydrological models

Science.gov (United States)

Singh, A.; Seitz, F.; Schwatke, C.; Güntner, A.

2012-04-01

Satellite altimetry is capable of measuring surface water level changes of large water bodies. This is especially interesting for regions where in-situ gauges are sparse or not available. Temporal variations of coastline and horizontal extent of a water body can be derived from optical remote sensing data. A joint analysis of both data types together with a digital elevation model allows for the estimation of water volume changes. Related variations of water mass map into the observations of the satellite gravity field mission GRACE. In this presentation, we demonstrate the application of heterogeneuous remote sensing methods for studying chages of water volume and mass of the Aral Sea and compare the results with respect to their consistency. Our analysis covers the period 2002-2011. In particular we deal with data from multi-mission radar and laser satellite altimetry that are analyzed in combination with coastlines from Landsat images. The resultant vertical and horizontal variations of the lake surface are geometrically intersected with the bathymetry of the Aral Sea in order to compute volumetric changes. These are transformed into variations of water mass that are subsequently compared with storage changes derived from GRACE satellite gravimetry. Hence we obtain a comprehensive picture of the hydrological changes in the region. Observations from all datasets correspond quite well with each other with respect to their temporal development. However, geometrically determined volume changes and mass changes observed by GRACE agree less well during years of heavy water inflow in to the Aral Sea from its southern tributary 'Amu Darya' since the GRACE signals are contaminated by the large mass of water stored in the river delta and prearalie region On the other hand, GRACE observations of the river basins of Syr Darya and Amu Dayra correspond very well with hydrological models and mass changes computed from the balance of precipitation, evaporation and runoff

Sequential assimilation of multi-mission dynamical topography into a global finite-element ocean model

Directory of Open Access Journals (Sweden)

S. Skachko

2008-12-01

Full Text Available This study focuses on an accurate estimation of ocean circulation via assimilation of satellite measurements of ocean dynamical topography into the global finite-element ocean model (FEOM. The dynamical topography data are derived from a complex analysis of multi-mission altimetry data combined with a referenced earth geoid. The assimilation is split into two parts. First, the mean dynamic topography is adjusted. To this end an adiabatic pressure correction method is used which reduces model divergence from the real evolution. Second, a sequential assimilation technique is applied to improve the representation of thermodynamical processes by assimilating the time varying dynamic topography. A method is used according to which the temperature and salinity are updated following the vertical structure of the first baroclinic mode. It is shown that the method leads to a partially successful assimilation approach reducing the rms difference between the model and data from 16 cm to 2 cm. This improvement of the mean state is accompanied by significant improvement of temporal variability in our analysis. However, it remains suboptimal, showing a tendency in the forecast phase of returning toward a free run without data assimilation. Both the mean difference and standard deviation of the difference between the forecast and observation data are reduced as the result of assimilation.

The eastern Tibetan Plateau geothermal belt, western China: Geology, geophysics, genesis, and hydrothermal system

Science.gov (United States)

Tang, Xianchun; Zhang, Jian; Pang, Zhonghe; Hu, Shengbiao; Tian, Jiao; Bao, Shujing

2017-10-01

The eastern Tibetan Plateau geothermal belt (ETGB), which is located in 98-102°E, 28-32°N, belongs to the eastern part of the Mediterranean-Himalayan geothermal belt. Recently, about 248 natural hot springs have been found in the ETGB. > 60% of these springs have temperatures of > 40 °C, and 11 springs have temperature above the local water boiling point. Using the helium isotopic data, gravity, magnetic and seismic data, we analyzed the thermal structure and the relationship between hydrothermal activity and geothermal dynamics of the ETGB. Results show that: (1) the 248 springs can be divided into three geothermal fields: Kangding-Luhuo geothermal field (KGF), Litang-Ganzi geothermal field (LGF) and Batang-Xiangcheng geothermal field (BGF). The BGF and LGF have hot crust and warm mantle, and are characterized by the higher heat flux (66.26 mW/m2), and higher ratios of crust-derived heat flux to total flux (47.46-60.62%). The KGF has cool crust and hot mantle, and is characterized by the higher heat flux and lower Qc/Qm; (2) there is a relatively 4-6 m higher gravimetric geoid anomaly dome which is corresponding with the ETGB. And in hydrothermal activity areas of the BGF and LGF, there is a northwest - southeast-trending tensile stress area and the upper-middle crust uplift area; (3) an abnormal layer exists in the middle-lower crust at a depth of 13-30 km beneath the ETGB, and this layer is 8-10 km thick and is characterized by lower velocity (Vp 2.5), high conductivity ( 10 Ω·m) and high temperature (850-1000 °C). Finally, based on the heat source and geological and geophysical background, we propose Kangding-type and Batang-type hydrothermal system models in the ETGB.

Identifying the risk: a prospective cohort study examining postpartum haemorrhage in a regional Australian health service.

Science.gov (United States)

Kearney, Lauren; Kynn, Mary; Reed, Rachel; Davenport, Lisa; Young, Jeanine; Schafer, Keppel

2018-06-07

In industrialised countries the incidence of postpartum haemorrhage (PPH) is increasing, for which exact etiology is not well understood. Studies have relied upon retrospective data with estimated blood loss as the primary outcome, known to be underestimated by clinicians. This study aimed to explore variables associated with PPH in a cohort of women birthing vaginally in coastal Queensland, Australia, using the gravimetric method to measure blood loss. Women were prospectively recruited to participate using an opt-out consent process. Maternal demographics; pregnancy history; model of care; mode of birth; third stage management practices; antenatal, intrapartum and immediate postpartum complications; gravimetric and estimated blood loss; and haematological laboratory data, were collected via a pre-designed data collection instrument. Descriptive statistics were used for demographic, intrapartum and birthing practices. A General Linear Model was used for multivariate analysis to examine relationship between gravimetric blood loss and demographic, birthing practices and intrapartum variables. The primary outcome was a postpartum haemorrhage (blood loss > 500 ml). 522 singleton births were included in the analysis. Maternal mean age was 29 years; 58% were multiparous. Most participants received active (291, 55.7%) or modified active management of third stage (191, 36.6%). Of 451 births with valid gravimetric blood loss recorded, 35% (n = 159) recorded a loss of 500 ml or more and 111 (70%) of these were recorded as PPH. Gravimetric blood loss was strongly correlated with estimated blood loss (r = 0.88; p gravimetric blood loss, about 78% of the measured value. High neonatal weight, perineal injury, complications during labour, separation of mother and baby, and observation of a gush of blood were associated with PPH. Nulliparity, labour induction and augmentation, syntocinon use were not associated with PPH. In contrast to previous study findings

Global Geopotential Energy & Stress Field

DEFF Research Database (Denmark)

Schiffer, Christian; Nielsen, S.B.

of the oceanic lithosphere. An entire modelling of the shallow Geopotential Energy is hereby approached, not taking into account possible deeper signals but all lithospheric signals for the subsequent stress calculation. Therefore a global lithospheric density model is necessary to calculate the corresponding...... response to Geopotential Energy and the Geoid. A linearized inverse method fits a lithospheric reference model to reproduce measured data sets, such as topography and surface heat flow, while assuming isostasy and solving the steady state heat equation. A FEM code solves the equations of equilibrium...

Evaluation of purity with its uncertainty value in high purity lead stick by conventional and electro-gravimetric methods.

Science.gov (United States)

Singh, Nahar; Singh, Niranjan; Tripathy, S Swarupa; Soni, Daya; Singh, Khem; Gupta, Prabhat K

2013-06-26

A conventional gravimetry and electro-gravimetry study has been carried out for the precise and accurate purity determination of lead (Pb) in high purity lead stick and for preparation of reference standard. Reference materials are standards containing a known amount of an analyte and provide a reference value to determine unknown concentrations or to calibrate analytical instruments. A stock solution of approximate 2 kg has been prepared after dissolving approximate 2 g of Pb stick in 5% ultra pure nitric acid. From the stock solution five replicates of approximate 50 g have been taken for determination of purity by each method. The Pb has been determined as PbSO4 by conventional gravimetry, as PbO2 by electro gravimetry. The percentage purity of the metallic Pb was calculated accordingly from PbSO4 and PbO2. On the basis of experimental observations it has been concluded that by conventional gravimetry and electro-gravimetry the purity of Pb was found to be 99.98 ± 0.24 and 99.97 ± 0.27 g/100 g and on the basis of Pb purity the concentration of reference standard solutions were found to be 1000.88 ± 2.44 and 1000.81 ± 2.68 mg kg-1 respectively with 95% confidence level (k = 2). The uncertainty evaluation has also been carried out in Pb determination following EURACHEM/GUM guidelines. The final analytical results quantifying uncertainty fulfills this requirement and gives a measure of the confidence level of the concerned laboratory. Gravimetry is the most reliable technique in comparison to titremetry and instrumental method and the results of gravimetry are directly traceable to SI unit. Gravimetric analysis, if methods are followed carefully, provides for exceedingly precise analysis. In classical gravimetry the major uncertainties are due to repeatability but in electro-gravimetry several other factors also affect the final results.

Assessment of the most recent satellite based digital elevation models of Egypt

Science.gov (United States)

Rabah, Mostafa; El-Hattab, Ahmed; Abdallah, Mohamed

2017-12-01

Digital Elevation Model (DEM) is crucial to a wide range of surveying and civil engineering applications worldwide. Some of the DEMs such as ASTER, SRTM1 and SRTM3 are freely available open source products. In order to evaluate the three DEMs, the contribution of EGM96 are removed and all DEMs heights are becoming ellipsoidal height. This step was done to avoid the errors occurred due to EGM96. 601 points of observed ellipsoidal heights compared with the three DEMs, the results show that the SRTM1 is the most accurate one, that produces mean height difference and standard deviations equal 2.89 and ±8.65 m respectively. In order to increase the accuracy of SRTM1 in EGYPT, a precise Global Geopotential Model (GGM) is needed to convert the SRTM1 ellipsoidal height to orthometric height, so that, we quantify the precision of most-recent released GGM (five models). The results show that, the GECO model is the best fit global models over Egypt, which produces a standard deviation of geoid undulation differences equals ±0.42 m over observed 17 HARN GPS/leveling stations. To confirm an enhanced DEM in EGYPT, the two orthometric height models (SRTM1 ellipsoidal height + EGM96) and (SRTM1 ellipsoidal height + GECO) are assessment with 17 GPS/leveling stations and 112 orthometric height stations, the results show that the estimated height differences between the SRTM1 before improvements and the enhanced model are at rate of 0.44 m and 0.06 m respectively.

Internal loading of an inhomogeneous compressible Earth with phase boundaries

Science.gov (United States)

Defraigne, P.; Dehant, V.; Wahr, J. M.

1996-01-01

The geoid and the boundary topography caused by mass loads inside the earth were estimated. It is shown that the estimates are affected by compressibility, by a radially varying density distribution, and by the presence of phase boundaries with density discontinuities. The geoid predicted in the chemical boundary case is 30 to 40 percent smaller than that predicted in the phase case. The effects of compressibility and radially varying density are likely to be small. The inner core-outer core topography for loading inside the mantle and for loading inside the inner core were computed.

Comparison of methods of calibration of a neutron probe by gravimetry or neutron-capture model

International Nuclear Information System (INIS)

Vachaud, G.; Royer, J.M.; Cooper, J.D.

1977-01-01

This paper presents a systematic analysis of two methods used for determining calibration curves of neutron probes. The uncertainties resulting from the use of the gravimetric method, with a linear correlation between count rates and water content of soil samples, are considered first. Particular care is given to the determination of errors in the values of water content and count rates, and to the difficulties arising from the choice of the correlation technique. The neutron-calibration curve of the soil was also obtained with a technique based on the determination of neutron thermal adsorption and diffusion constants. The importance of errors associated with this method is also analyzed. Different field examples are then presented. It appears that the neutron-capture technique should be particularly well suited for determining the calibration curve of clay soils or heterogeneous materials for which the gravimetric calibration technique cannot be applied with confidence. On the other hand, it is also shown that for a soil with a very well-defined gravimetric calibration curve, the neutron-capture technique gives results still at least as good as with the former method

The Addition of Enhanced Capabilities to NATO GMTIF STANAG 4607 to Support RADARSAT-2 GMTI Data

Science.gov (United States)

2007-12-01

However, the cost is a loss in the accuracy of the position specification and its dependence on the particular ellipsoid and/or geoid models used in...platform provides these parameters. Table B-3. Reference Coordinate Systems COORDINATE SYSTEM VALUE Unidentified 0 GEI: Geocentric Equatorial...Inertial, also known as True Equator and True Equinox of Date, True of Date (TOD), ECI, or GCI 1 J2000: Geocentric Equatorial Inertial for epoch J2000.0

Sea-ice thickness from airborne laser altimetry over the Arctic Ocean north of Greenland

DEFF Research Database (Denmark)

Hvidegaard, Sine Munk; Forsberg, René

2002-01-01

We present a new method to measure ice thickness of polar sea-ice freeboard heights, using airborne laser altimetry combined with a precise geoid model, giving estimates of thickness of ice through isostatic equilibrium assumptions. In the paper we analyze a number of flights from the Polar Sea off...... Northern Greenland, and estimate accuracies of the estimated freeboard values to be at a 13 cm level, corresponding to about 1 m in absolute thickness....

Modeling PM10 gravimetric data from the Qalabotjha low-smoke fuels macro-scale experiment in South Africa

International Nuclear Information System (INIS)

Engelbrecht, J.P.; Swanepoel, L.; Zunckel, M.; Chow, J.C.

1998-01-01

D-grade domestic coal is being widely used for household cooking and heating purposes by the poorer urban communities in South Africa. The smoke from the combustion of coal has had a severe impact on the health of communities living in the rural townships and cities. To alleviate this escalating problem, the Department of Minerals and Energy of South Africa evaluated low-smoke fuels as an alternative source of energy. The technical and social implications of such fuels were investigated in the course of the Qalabotjha Low-Smoke Fuels Macro-Scale Experiment. Three low-smoke fuels (Chartech, African Fine Carbon (AFC) and Flame Africa) were tested in Qalabotjha over a 10 to 20 day period. This paper presents results from a PM10 TEOM continuous monitor at the Clinic site in Qalabotjha over the mentioned monitoring period. Both the fuel-type and the wind were found to have an effect on the air particulate concentrations. An exponential model which incorporates both these variables is proposed. This model allows for all measured particulate concentrations to be re-calculated to zero wind values. From the analysis of variance (ANOVA) calculations on the zero wind concentrations, it is concluded that the combustion of low-smoke fuels did make a significant improvement to the air quality in Qalabotjha over the period when these were used

The electrochemistry and modelling of hydrogen storage materials

International Nuclear Information System (INIS)

Kalisvaart, W.P.; Vermeulen, P.; Ledovskikh, A.V.; Danilov, D.; Notten, P.H.L.

2007-01-01

Mg-based alloys are promising hydrogen storage materials because of the high gravimetric energy density of MgH 2 (7.6 wt.%). A major disadvantage, however, is its very slow desorption kinetics. It has been argued that, in contrast to the well-known rutile-structured Mg hydride, hydrided Mg-transition metal alloys have a much more open crystal structure facilitating faster hydrogen transport. In this paper, the electrochemical aspects of new Mg-Sc and Mg-Ti materials will be reviewed. Storage capacities as high as 6.5 wt.% hydrogen have been reached with very favourable discharge kinetics. A theoretical description of hydrogen storage materials has also been developed by our group. A new lattice gas model is presented and successfully applied to simulate the thermodynamic properties of various hydride-forming materials. The simulation results are expressed by parameters corresponding to several energy contributions, for example mutual atomic hydrogen interaction energies. A good fit of the lattice gas model to the experimental data is found in all cases

Modeling and estimation of a low degree geopotential model from terrestrial gravity data

Science.gov (United States)

Pavlis, Nikolaos K.

1988-01-01

The development of appropriate modeling and adjustment procedures for the estimation of harmonic coefficients of the geopotential, from surface gravity data was studied, in order to provide an optimum way of utilizing the terrestrial gravity information in combination solutions currently developed at NASA/Goddard Space Flight Center, for use in the TOPEX/POSEIDON mission. The mathematical modeling was based on the fundamental boundary condition of the linearized Molodensky boundary value problem. Atmospheric and ellipsoidal corrections were applied to the surface anomalies. Terrestrial gravity solutions were found to be in good agreement with the satellite ones over areas which are well surveyed (gravimetrically), such as North America or Australia. However, systematic differences between the terrestrial only models and GEMT1, over extended regions in Africa, the Soviet Union, and China were found. In Africa, gravity anomaly differences on the order of 20 mgals and undulation differences on the order of 15 meters, over regions extending 2000 km in diameter, occur. Comparisons of the GEMT1 implied undulations with 32 well distributed Doppler derived undulations gave an RMS difference of 2.6 m, while corresponding comparison with undulations implied by the terrestrial solution gave RMS difference on the order of 15 m, which implies that the terrestrial data in that region are substantially in error.

The Earth Gravitational Model 1996: The NCCS: Resource for Development, Resource for the Future

Science.gov (United States)

2002-01-01

For centuries, men have attempted to understand the climate system through observations obtained from Earth's surface. These observations yielded preliminary understanding of the ocean currents, tides, and prevailing winds using visual observation and simple mechanical tools as their instruments. Today's sensitive, downward-looking radar systems, called altimeters, onboard satellites can measure globally the precise height of the ocean surface. This surface is largely that of the equipotential gravity surface, called the geoid - the level surface to which the oceans would conform if there were no forces acting on them apart from gravity, as well as having a significant 1-2- meter-level signal arising from the motion of the ocean's currents.

A GOCE only gravity model GOSG01S and the validation of GOCE related satellite gravity models

Directory of Open Access Journals (Sweden)

Xinyu Xu

2017-07-01

Full Text Available We compile the GOCE-only satellite model GOSG01S complete to spherical harmonic degree of 220 using Satellite Gravity Gradiometry (SGG data and the Satellite-to-Satellite Tracking (SST observations along the GOCE orbit based on applying a least-squares analysis. The diagonal components (Vxx, Vyy, Vzz of the gravitational gradient tensor are used to form the system of observation equations with the band-pass ARMA filter. The point-wise acceleration observations (ax, ay, az along the orbit are used to form the system of observation equations up to the maximum spherical harmonic degree/order 130. The analysis of spectral accuracy characteristics of the newly derived gravitational model GOSG01S and the existing models GOTIM04S, GODIR04S, GOSPW04S and JYY_GOCE02S based on their comparison with the ultra-high degree model EIGEN-6C2 reveals a significant consistency at the spectral window approximately between 80 and 190 due to the same period SGG data used to compile these models. The GOCE related satellite gravity models GOSG01S, GOTIM05S, GODIR05S, GOTIM04S, GODIR04S, GOSPW04S, JYY_GOCE02S, EIGEN-6C2 and EGM2008 are also validated by using GPS-leveling data in China and USA. According to the truncation at degree 200, the statistic results show that all GGMs have very similar differences at GPS-leveling points in USA, and all GOCE related gravity models have better performance than EGM2008 in China. This suggests that all these models provide much more information on the gravity field than EGM2008 in areas with low terrestrial gravity coverage. And STDs of height anomaly differences in China for the selected truncation degrees show that GOCE has improved the accuracy of the global models beyond degree 90 and the accuracies of the models improve from 24 cm to 16 cm. STDs of geoid height differences in USA show that GOSG01S model has best consistency comparing with GPS-leveling data for the frequency band of the degree between 20 and 160.

Origin and Evolution of the Yellowstone Hotspot from Seismic-GPS Imaging and Geodynamic Modeling

Science.gov (United States)

Smith, R. B.; Jordan, M.; Puskas, C. M.; Farrell, J.; Waite, G. P.

2006-12-01

The Yellowstone hotspot resulted from interaction of a mantle plume with the overriding North America plate. This feature and related processes have influenced a large part of the western U.S., producing the 16 Ma Yellowstone-Snake River Plain-Newberry silicic-basalt volcanic field (YSRPN). We integrate results from a multi-institution experiment that deployed 80 seismic stations and 160 campaign and 21 permanent GPS stations for 1999-2003. Crust and mantle velocity models were derived from inversion of teleseismic and local earthquake data. Kinematic and dynamic models were derived from inversion of GPS velocities constrained by stresses associated the topography and the +15 m geoid anomaly. Tomography revealed a P- and S-wave low-velocity body at depths of 8-16 km beneath the caldera that is interpreted as partial melt of 8-15% that feeds the youthful Yellowstone volcanic field. Volume changes in the magma chamber are responsible for GPS-measured episodes of uplift and subsidence of the caldera at decadal scales with average rates of ~20 mm/yr but much higher short-term rates of up to 80 mm/yr. An upper-mantle low-velocity body was imaged by inverting teleseismic data constrained by the geoid structure, crustal structure, and the upper mantle discontinuities. This low P and S velocity body extends from 80 km to ~250 km directly beneath Yellowstone and then continues to 650 km with unexpected tilt to the west at ~60°. The tilt is consistent with the ascent of the buoyant magma entrained in eastward return-flow of the upper mantle. We estimate this body has an excess temperature from 85K to 120K, depending on the water content and with up to 1.5% melt. Using the inclined plume-geometry and plate motion history, we extrapolate the Yellowstone mantle source southwestward ~800 km as a plume-head in oceanic lithosphere centered beneath the Columbia Plateau basalt field at 16 Ma. Magma ascent was truncated there by the passage of thicker continental lithosphere over

Adsorption and Corrosion Inhibition Studies of Some Selected Dyes as Corrosion Inhibitors for Mild Steel in Acidic Medium: Gravimetric, Electrochemical, Quantum Chemical Studies and Synergistic Effect with Iodide Ions

Directory of Open Access Journals (Sweden)

Thabo Peme

2015-09-01

Full Text Available The corrosion inhibition properties of some organic dyes, namely Sunset Yellow (SS, Amaranth (AM, Allura Red (AR, Tartrazine (TZ and Fast Green (FG, for mild steel corrosion in 0.5 M HCl solution, were investigated using gravimetric, potentiodynamic polarization techniques and quantum chemical calculations. The results showed that the studied dyes are good corrosion inhibitors with enhanced inhibition efficiencies. The inhibition efficiency of all the studied dyes increases with increase in concentration, and decreases with increase in temperature. The results showed that the inhibition efficiency of the dyes increases in the presence of KI due to synergistic interactions of the dye molecules with iodide (I− ions. Potentiodynamic polarization results revealed that the studied dyes are mixed-type inhibitors both in the absence and presence of KI. The adsorption of the studied dyes on mild steel surface, with and without KI, obeys the Langmuir adsorption isotherm and involves physical adsorption mechanism. Quantum chemical calculations revealed that the most likely sites in the dye molecules for interactions with mild steel are the S, O, and N heteroatoms.

Adsorption and Corrosion Inhibition Studies of Some Selected Dyes as Corrosion Inhibitors for Mild Steel in Acidic Medium: Gravimetric, Electrochemical, Quantum Chemical Studies and Synergistic Effect with Iodide Ions.

Science.gov (United States)

Peme, Thabo; Olasunkanmi, Lukman O; Bahadur, Indra; Adekunle, Abolanle S; Kabanda, Mwadham M; Ebenso, Eno E

2015-09-02

The corrosion inhibition properties of some organic dyes, namely Sunset Yellow (SS), Amaranth (AM), Allura Red (AR), Tartrazine (TZ) and Fast Green (FG), for mild steel corrosion in 0.5 M HCl solution, were investigated using gravimetric, potentiodynamic polarization techniques and quantum chemical calculations. The results showed that the studied dyes are good corrosion inhibitors with enhanced inhibition efficiencies. The inhibition efficiency of all the studied dyes increases with increase in concentration, and decreases with increase in temperature. The results showed that the inhibition efficiency of the dyes increases in the presence of KI due to synergistic interactions of the dye molecules with iodide (I(-)) ions. Potentiodynamic polarization results revealed that the studied dyes are mixed-type inhibitors both in the absence and presence of KI. The adsorption of the studied dyes on mild steel surface, with and without KI, obeys the Langmuir adsorption isotherm and involves physical adsorption mechanism. Quantum chemical calculations revealed that the most likely sites in the dye molecules for interactions with mild steel are the S, O, and N heteroatoms.

International Digital Elevation Model Service (IDEMS): A Revived IAG Service

Science.gov (United States)

Kelly, K. M.; Hirt, C., , Dr; Kuhn, M.; Barzaghi, R.

2017-12-01

A newly developed International Digital Elevation Model Service (IDEMS) is now available under the umbrella of the International Gravity Field Service of the International Association of Geodesy. Hosted and operated by Environmental Systems Research Institute (Esri) (http://www.esri.com/), the new IDEMS website is available at: https://idems.maps.arcgis.com/home/index.html. IDEMS provides a focus for distribution of data and information about various digital elevation models, including spherical-harmonic models of Earth's global topography and lunar and planetary DEM. Related datasets, such as representation of inland water within DEMs, and relevant software which are available in the public domain are also provided. Currently, IDEMS serves as repository of links to providers of global terrain and bathymetry, terrain related Earth models and datasets such as digital elevation data services managed and maintained by Esri (Terrain and TopoBathy), Bedmap2-Ice thickness and subglacial topographic model of Antarctica and Ice, Cloud, and Land Elevation ICESat/GLAS Data, as well as planetary terrain data provided by PDS Geosciences Node at Washington University, St. Louis. These services provide online access to a collection of multi-resolution and multi-source elevation and bathymetry data, including metadata and source information. In addition to IDEMS current holdings of terrestrial and planetary DEMs, some topography related products IDEMS may include in future are: dynamic ocean topography, 3D crustal density models, Earth's dynamic topography, etc. IDEMS may also consider terrain related products such as quality assessments, global terrain corrections, global height anomaly-to-geoid height corrections and other geodesy-relevant studies and products. IDEMS encourages contributions to the site from the geodetic community in any of the product types listed above. Please contact the authors if you would like to contribute or recommend content you think appropriate for

ACCURACY ASSESSMENT OF RECENT GLOBAL OCEAN TIDE MODELS AROUND ANTARCTICA

Directory of Open Access Journals (Sweden)

J. Lei

2017-09-01

Full Text Available Due to the coverage limitation of T/P-series altimeters, the lack of bathymetric data under large ice shelves, and the inaccurate definitions of coastlines and grounding lines, the accuracy of ocean tide models around Antarctica is poorer than those in deep oceans. Using tidal measurements from tide gauges, gravimetric data and GPS records, the accuracy of seven state-of-the-art global ocean tide models (DTU10, EOT11a, GOT4.8, FES2012, FES2014, HAMTIDE12, TPXO8 is assessed, as well as the most widely-used conventional model FES2004. Four regions (Antarctic Peninsula region, Amery ice shelf region, Filchner-Ronne ice shelf region and Ross ice shelf region are separately reported. The standard deviations of eight main constituents between the selected models are large in polar regions, especially under the big ice shelves, suggesting that the uncertainty in these regions remain large. Comparisons with in situ tidal measurements show that the most accurate model is TPXO8, and all models show worst performance in Weddell sea and Filchner-Ronne ice shelf regions. The accuracy of tidal predictions around Antarctica is gradually improving.

Accuracy Assessment of Recent Global Ocean Tide Models around Antarctica

Science.gov (United States)

Lei, J.; Li, F.; Zhang, S.; Ke, H.; Zhang, Q.; Li, W.

2017-09-01

Due to the coverage limitation of T/P-series altimeters, the lack of bathymetric data under large ice shelves, and the inaccurate definitions of coastlines and grounding lines, the accuracy of ocean tide models around Antarctica is poorer than those in deep oceans. Using tidal measurements from tide gauges, gravimetric data and GPS records, the accuracy of seven state-of-the-art global ocean tide models (DTU10, EOT11a, GOT4.8, FES2012, FES2014, HAMTIDE12, TPXO8) is assessed, as well as the most widely-used conventional model FES2004. Four regions (Antarctic Peninsula region, Amery ice shelf region, Filchner-Ronne ice shelf region and Ross ice shelf region) are separately reported. The standard deviations of eight main constituents between the selected models are large in polar regions, especially under the big ice shelves, suggesting that the uncertainty in these regions remain large. Comparisons with in situ tidal measurements show that the most accurate model is TPXO8, and all models show worst performance in Weddell sea and Filchner-Ronne ice shelf regions. The accuracy of tidal predictions around Antarctica is gradually improving.

Integrating gravimetric and interferometric synthetic aperture radar data for enhancing reservoir history matching of carbonate gas and volatile oil reservoirs

KAUST Repository

Katterbauer, Klemens

2016-08-25

Reservoir history matching is assuming a critical role in understanding reservoir characteristics, tracking water fronts, and forecasting production. While production data have been incorporated for matching reservoir production levels and estimating critical reservoir parameters, the sparse spatial nature of this dataset limits the efficiency of the history matching process. Recently, gravimetry techniques have significantly advanced to the point of providing measurement accuracy in the microgal range and consequently can be used for the tracking of gas displacement caused by water influx. While gravity measurements provide information on subsurface density changes, i.e., the composition of the reservoir, these data do only yield marginal information about temporal displacements of oil and inflowing water. We propose to complement gravimetric data with interferometric synthetic aperture radar surface deformation data to exploit the strong pressure deformation relationship for enhancing fluid flow direction forecasts. We have developed an ensemble Kalman-filter-based history matching framework for gas, gas condensate, and volatile oil reservoirs, which synergizes time-lapse gravity and interferometric synthetic aperture radar data for improved reservoir management and reservoir forecasts. Based on a dual state-parameter estimation algorithm separating the estimation of static reservoir parameters from the dynamic reservoir parameters, our numerical experiments demonstrate that history matching gravity measurements allow monitoring the density changes caused by oil-gas phase transition and water influx to determine the saturation levels, whereas the interferometric synthetic aperture radar measurements help to improve the forecasts of hydrocarbon production and water displacement directions. The reservoir estimates resulting from the dual filtering scheme are on average 20%-40% better than those from the joint estimation scheme, but require about a 30% increase in

On the assimilation of absolute geodetic dynamic topography in a global ocean model: impact on the deep ocean state

Science.gov (United States)

Androsov, Alexey; Nerger, Lars; Schnur, Reiner; Schröter, Jens; Albertella, Alberta; Rummel, Reiner; Savcenko, Roman; Bosch, Wolfgang; Skachko, Sergey; Danilov, Sergey

2018-05-01

General ocean circulation models are not perfect. Forced with observed atmospheric fluxes they gradually drift away from measured distributions of temperature and salinity. We suggest data assimilation of absolute dynamical ocean topography (DOT) observed from space geodetic missions as an option to reduce these differences. Sea surface information of DOT is transferred into the deep ocean by defining the analysed ocean state as a weighted average of an ensemble of fully consistent model solutions using an error-subspace ensemble Kalman filter technique. Success of the technique is demonstrated by assimilation into a global configuration of the ocean circulation model FESOM over 1 year. The dynamic ocean topography data are obtained from a combination of multi-satellite altimetry and geoid measurements. The assimilation result is assessed using independent temperature and salinity analysis derived from profiling buoys of the AGRO float data set. The largest impact of the assimilation occurs at the first few analysis steps where both the model ocean topography and the steric height (i.e. temperature and salinity) are improved. The continued data assimilation over 1 year further improves the model state gradually. Deep ocean fields quickly adjust in a sustained manner: A model forecast initialized from the model state estimated by the data assimilation after only 1 month shows that improvements induced by the data assimilation remain in the model state for a long time. Even after 11 months, the modelled ocean topography and temperature fields show smaller errors than the model forecast without any data assimilation.

3D Gravimetric Modeling of the Spreading System North and Southeast of the Rodriguez Triple Junction (Indian Ocean)

Science.gov (United States)

Heyde, I.; Girolami, C.; Barckhausen, U.; Freitag, R.

2017-12-01

Hydrothermal vent fields along mid-ocean ridges can be metal-rich and thus of great importance for the industries in the future. By order of the German Federal Ministry of Economics and in coordination with the International Seabed Authority (ISA), BGR explores potential areas of the active spreading system in the Indian Ocean. A main goal is the identification of inactive seafloor massive sulfides (SMS) with the aid of modern exploration techniques. Important contributions could be expected from bathymetric, magnetic, and gravity datasets, which can be acquired simultaneously time from the sea surface within relatively short ship time. The area of interest is located between 21°S and 28°S and includes the southern Central Indian Ridge (CIR) and the northern Southeast Indian Ridge (SEIR). In this study we analyzed the marine gravity and bathymetric data acquired during six research cruises. The profiles running perpendicular to the ridge axis have a mean length of 60 km. Magnetic studies reveal that the parts of the ridges covered are geologically very young with the oldest crust dating back to about 1 Ma. To extend the area outside the ridges, the shipboard data were complemented with data derived from satellite radar altimeter measurements. We analyzed the gravity anomalies along sections which cross particular geologic features (uplifted areas, accommodation zones, hydrothermal fields, and areas with hints for extensional processes e.g. oceanic core complexes) to establish a correlation between the gravity anomalies and the surface geology. Subsequently, for both ridge segments 3D density models were developed. We started with simple horizontally layered models, which, however, do not explain the measured anomalies satisfyingly. The density values of the crust and the upper mantle in the ridge areas had to be reduced. Finally, the models show the lateral heterogeneity and the variations in the thickness of the oceanic crust. There are areas characterized by

Effect of the Earth's inner structure on the gravity in definitions of height systems

Science.gov (United States)

Tenzer, Robert; Foroughi, Ismael; Pitoňák, Martin; Šprlák, Michal

2017-04-01

In context of the vertical datum unification, the geoid-to-quasi-geoid separation has been of significant interest in recent years, because most of existing local vertical datums are realized in the system of either normal or orthometric heights. Nevertheless, the normal-orthometric heights are still used in many other countries where the normal gravity values along leveling lines were adopted instead of the observed gravity. Whereas the conversion between the orthometric and normal heights is defined by means of the mean gravity disturbances (i.e. differences between the mean values of the actual and normal gravity) along the plumbline within the topography, differences between the normal and normal-orthometric heights can be described by means of the surface gravity disturbances. Since the normal gravity field does not reflect the topographic masses and actual mass density distribution inside the Earth, the definition of gravity represents a principal aspect for a realization of particular vertical datum. To address this issue in this study, we investigate effects of the Earth's inner density structure on the surface and mean gravity disturbances, and discuss their impact on the vertical datum realization. These two gravity field quantities are computed globally with a spectral resolution complete to a spherical harmonic degree 2160 using the global gravity, terrain, ice-thickness, inland bathymetry and crustal structure models. Our results reveal that both, the surface and mean gravity disturbances mostly comprise the gravitational signal of topography and masses distributed below the geoid surface. Moreover, in polar areas, a significant contribution comes from large glaciers. In contrast, the contributions of anomalous density distribution within the topography attributed to major lakes, sediments and bedrock density variations are much less pronounced. We also demonstrate that the mean gravity disturbances within the topography are significantly modified

A three-dimensional gravity inversion applied to São Miguel Island (Azores)

Science.gov (United States)

Camacho, A. G.; Montesinos, F. G.; Vieira, R.

1997-04-01

Gravimetric studies are becoming more and more widely acknowledged as a useful tool for studying and modeling the distributions of subsurface masses that are associated with volcanic activity. In this paper, new gravimetric data for the volcanic island of São Miguel (Azores) were analyzed and interpreted by a stabilized linear inversion methodology. An inversion model of higher resolution was calculated for the Caldera of Furnas, which has a larger density of data. In order to filter out the noncorrelatable anomalies, least squares prediction was used, resulting in a correlated gravimetric signal model with an accuracy of the order of 0.9 mGal. The gravimetric inversion technique is based on the adjustment of a three-dimensional (3-D) model of cubes of unknown density that represents the island's subsurface. The problem of non-uniqueness is solved by minimization with appropriate covariance matrices of the data (resulting from the least squares prediction) and of the unknowns. We also propose a criterion for choosing a balance between the data fit (which in this case corresponds to residues with rms of the order of 0.6 mGal) and the smoothness of the solution. The global model of the island includes a low-density zone in a WNW-ESE direction and a depth of the order of 20 km, associated with the Terceira rift spreading center. The minimums located at a depth of 4 km may be associated with shallow magmatic chambers beneath the main volcanoes of the island. The main high-density area is related to the Nordeste basaltic shield. With regard to the Caldera Furnas, in addition to the minimum that can be associated with a magmatic chamber, there are other shallow minimums that correspond to eruptive processes.

Mathematical Modeling of Moisture Sorption Isotherms and Determination of Isosteric Heats of Sorption of Ziziphus Leaves

Directory of Open Access Journals (Sweden)

Amel Saad

2014-01-01

Full Text Available Desorption and adsorption equilibrium moisture isotherms of Ziziphus spina-christi leaves were determined using the gravimetric-static method at 30, 40, and 50°C for water activity (aw ranging from 0.057 to 0.898. At a given aw, the results show that the moisture content decreases with increasing temperature. A hysteresis effect was observed. The experimental data of sorption were fitted by eight models (GAB, BET, Henderson-Thompson, modified-Chung Pfost, Halsey, Oswin, Peleg, and Adam and Shove. After evaluating the models according to several criteria, the Peleg and Oswin models were found to be the most suitable for describing the sorption curves. The net isosteric heats of desorption and adsorption of Ziziphus spina-christi leaves were calculated by applying the Clausius-Clapeyron equation to the sorption isotherms and an expression for predicting these thermodynamic properties was given.

A gelatin-free model system for the study of the basic radiation-induced polymerization in PAG dosimeters

International Nuclear Information System (INIS)

Babic, S; Park, Y S; Schreiner, L J

2004-01-01

In this presentation we show results of investigations on gelatin-free dosimeters containing equal amounts of acrylamide and N,N'-methylene-bisacrylamide (named Aqueous Polyacrylamide, APA, dosimeters). The dosimeters were prepared with three different total monomer concentrations (2, 6, and 8% by weight). Nuclear magnetic resonance (NMR) spin-spin and spin-lattice proton relaxation measurements at 20 MHz, and gravimetric analyses performed on all three dosimeters, show a continuous degree of polymerization over the range of dose 0.5 - 25 Gy. The developed NMR model explains the relationship observed between the relaxation data and the amount of cross-linked polymer formed at each dose. This model may be extended with gelatin relaxation data to provide a fundamental understanding of radiation-induced polymerization in the conventional PAG dosimeters

Multi data reservior history matching and uncertainty quantification framework

KAUST Repository

Katterbauer, Klemens

2015-11-26

A multi-data reservoir history matching and uncertainty quantification framework is provided. The framework can utilize multiple data sets such as production, seismic, electromagnetic, gravimetric and surface deformation data for improving the history matching process. The framework can consist of a geological model that is interfaced with a reservoir simulator. The reservoir simulator can interface with seismic, electromagnetic, gravimetric and surface deformation modules to predict the corresponding observations. The observations can then be incorporated into a recursive filter that subsequently updates the model state and parameters distributions, providing a general framework to quantify and eventually reduce with the data, uncertainty in the estimated reservoir state and parameters.

Geoid Model and Altitude at Mount Aconcagua Region (Argentina) from Airborne Gravity Survey

DEFF Research Database (Denmark)

Cristina Pacino, M.; Jaeger, Eric; Forsberg, René

2014-01-01

Aconcagua is part of the Southern Andes in the Argentine Province of Mendoza and it is the highest mountain in the Americas. The Aconcagua region is mostly inaccessible for land surveys. The existing gravity data are sparsely distributed, and mainly along the route currently used to climb the mou...

Titan's geoid and hydrology: implications for Titan's geological evolution

Science.gov (United States)

Sotin, Christophe; Seignovert, Benoit; Lawrence, Kenneth; MacKenzie, Shannon; Barnes, Jason; Brown, Robert

2014-05-01

A 1x1 degree altitude map of Titan is constructed from the degree 4 gravity potential [1] and Titan's shape [2] determined by the Radio Science measurements and RADAR observations of the Cassini mission. The amplitude of the latitudinal altitude variations is equal to 300 m compared to 600 m for the amplitude of the latitudinal shape variations. The two polar caps form marked depressions with an abrupt change in topography at exactly 60 degrees at both caps. Three models are envisaged to explain the low altitude of the polar caps: (i) thinner ice crust due to higher heat flux at the poles, (ii) fossil shape acquired if Titan had higher spin rate in the past, and (iii) subsidence of the crust following the formation of a denser layer of clathrates as ethane rain reacts with the H2O ice crust [3]. The later model is favored because of the strong correlation between the location of the cloud system during the winter season and the latitude of the abrupt change in altitude. Low altitude polar caps would be the place where liquids would run to and eventually form large seas. Indeed, the large seas of Titan are found at the deepest locations at the North Pole. However, the lakes and terrains considered to be evaporite candidates due to their spectral characteristics in the infrared [4,5] seem to be perched. Lakes may have been filled during Titan's winter and then slowly evaporated leaving material on the surface. Interestingly, the largest evaporite deposits are located at the equator in a deep depression 150 m below the altitude of the northern seas. This observation seems to rule out the presence of a global subsurface hydrocarbon reservoir unless the evaporation rate at the equator is faster than the transport of fluids from the North Pole to the equator. This work has been performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA. [1] Iess L. et al. (2012) Science, doi 10.1126/science.1219631. [2] Lorenz R.D. (2013

Drag-Free Motion Control of Satellite for High-Precision Gravity Field Mapping

DEFF Research Database (Denmark)

Ziegler, Bent Lindvig; Blanke, Mogens

2002-01-01

High precision mapping of the geoid and the Earth's gravity field are of importance to a wide range of ongoing studies in areas like ocean circulation, solid Earth physics and ice sheet dynamics. Using a satellite in orbit around the Earth gives the opportunity to map the Earth's gravity field in 3...... will compromise measurement accuracy, unless they are accurately compensated by on-board thrusters. The paper concerns the design of a control system to performing such delicate drag compensation. A six degrees-of-freedom model for the satellite is developed with the model including dynamics of the satellite...

Isothermal CO2 Gasification Reactivity and Kinetic Models of Biomass Char/Anthracite Char

Directory of Open Access Journals (Sweden)

Hai-Bin Zuo

2015-07-01

Full Text Available Gasification of four biomass chars and anthracite char were investigated under a CO2 atmosphere using a thermo-gravimetric analyzer. Reactivity differences of chars were considered in terms of pyrolysis temperature, char types, crystallinity, and inherent minerals. The results show that the gasification reactivity of char decreased with the increase of pyrolysis temperature. Char gasification reactivity followed the order of anthracite coal char (AC-char ˂ pine sawdust char (PS-char ˂ peanut hull char (PH-char ˂ wheat straw char (WS-char ˂ corncob char (CB-char under the same pyrolysis temperature. Two repesentative gas-solid models, the random pore model (RPM and the modified random pore model (MRPM, were applied to describe the reactive behaviour of chars. The results indicate RPM performs well to describe gasification rates of chars but cannot predict the phenomenon that there appears to exist a peak conversion for biomass chars at a high conversion rate, where the MRPM performs better.

Receptor models for source apportionment of remote aerosols in Brazil

International Nuclear Information System (INIS)

Artaxo Netto, P.E.

1985-11-01

The PIXE (particle induced X-ray emission), and PESA (proton elastic scattering analysis) method were used in conjunction with receptor models for source apportionment of remote aerosols in Brazil. The PIXE used in the determination of concentration for elements with Z >- 11, has a detection limit of about 1 ng/m 3 . The concentrations of carbon, nitrogen and oxygen in the fine fraction of Amazon Basin aerosols was measured by PESA. We sampled in Jureia (SP), Fernando de Noronha, Arembepe (BA), Firminopolis (GO), Itaberai (GO) and Amazon Basin. For collecting the airbone particles we used cascade impactors, stacked filter units, and streaker samplers. Three receptor models were used: chemical mass balance, stepwise multiple regression analysis and principal factor analysis. The elemental and gravimetric concentrations were explained by the models within the experimental errors. Three sources of aerosol were quantitatively distinguished: marine aerosol, soil dust and aerosols related to forests. The emission of aerosols by vegetation is very clear for all the sampling sites. In Amazon Basin and Jureia it is the major source, responsible for 60 to 80% of airborne concentrations. (Author) [pt

Dynamic–gravimetric preparation of metrologically traceable primary calibration standards for halogenated greenhouse gases

Directory of Open Access Journals (Sweden)

M. Guillevic

2018-06-01

Full Text Available For many years, the comparability of measurements obtained with various instruments within a global-scale air quality monitoring network has been ensured by anchoring all results to a unique suite of reference gas mixtures, also called a primary calibration scale. Such suites of reference gas mixtures are usually prepared and then stored over decades in pressurised cylinders by a designated laboratory. For the halogenated gases which have been measured over the last 40 years, this anchoring method is highly relevant as measurement reproducibility is currently much better ( <  1 %, k  =  2 or 95 % confidence interval than the expanded uncertainty of a reference gas mixture (usually  >  2 %. Meanwhile, newly emitted halogenated gases are already measured in the atmosphere at pmol mol−1 levels, while still lacking an established reference standard. For compounds prone to adsorption on material surfaces, it is difficult to evaluate mixture stability and thus variations in the molar fractions over time in cylinders at pmol mol−1 levels.To support atmospheric monitoring of halogenated gases, we create new primary calibration scales for SF6 (sulfur hexafluoride, HFC-125 (pentafluoroethane, HFO-1234yf (or HFC-1234yf, 2,3,3,3-tetrafluoroprop-1-ene, HCFC-132b (1,2-dichloro-1,1-difluoroethane and CFC-13 (chlorotrifluoromethane. The preparation method, newly applied to halocarbons, is dynamic and gravimetric: it is based on the permeation principle followed by dynamic dilution and cryo-filling of the mixture in cylinders. The obtained METAS-2017 primary calibration scales are made of 11 cylinders containing these five substances at near-ambient and slightly varying molar fractions. Each prepared molar fraction is traceable to the realisation of SI units (International System of Units and is assigned an uncertainty estimate following international guidelines (JCGM, 2008, ranging from 0.6 % for SF6 to 1.3 % (k�

Measuring and modelling of diffusivities in carbohydrate-rich matrices during thin film drying

NARCIS (Netherlands)

Perdana, J.A.; Sman, van der R.G.M.; Fox, M.B.; Boom, R.M.; Schutyser, M.A.I.

2014-01-01

Knowledge about moisture diffusivity in solid matrices is a key for understanding drying behaviour of for example probiotic or enzymatic formulations. This paper presents an experimental procedure to determine moisture diffusivity on the basis of thin film drying and gravimetric analysis in a

Global height datum unification: a new approach in gravity potential space

Science.gov (United States)

Ardalan, A. A.; Safari, A.

2005-12-01

The problem of “global height datum unification” is solved in the gravity potential space based on: (1) high-resolution local gravity field modeling, (2) geocentric coordinates of the reference benchmark, and (3) a known value of the geoid’s potential. The high-resolution local gravity field model is derived based on a solution of the fixed-free two-boundary-value problem of the Earth’s gravity field using (a) potential difference values (from precise leveling), (b) modulus of the gravity vector (from gravimetry), (c) astronomical longitude and latitude (from geodetic astronomy and/or combination of (GNSS) Global Navigation Satellite System observations with total station measurements), (d) and satellite altimetry. Knowing the height of the reference benchmark in the national height system and its geocentric GNSS coordinates, and using the derived high-resolution local gravity field model, the gravity potential value of the zero point of the height system is computed. The difference between the derived gravity potential value of the zero point of the height system and the geoid’s potential value is computed. This potential difference gives the offset of the zero point of the height system from geoid in the “potential space”, which is transferred into “geometry space” using the transformation formula derived in this paper. The method was applied to the computation of the offset of the zero point of the Iranian height datum from the geoid’s potential value W 0=62636855.8 m2/s2. According to the geometry space computations, the height datum of Iran is 0.09 m below the geoid.

The role of upper mantle mineral phase transitions on the current structure of large-scale Earth's mantle convection.

Science.gov (United States)

Thoraval, C.

2017-12-01

Describing the large-scale structures of mantle convection and quantifying the mass transfer between upper and lower mantle request to account for the role played by mineral phase transitions in the transition zone. We build a density distribution within the Earth mantle from velocity anomalies described by global seismic tomographic models. The density distribution includes thermal anomalies and topographies of the phase transitions at depths of 410 and 660 km. We compute the flow driven by this density distribution using a 3D spherical circulation model, which account for depth-dependent viscosity. The dynamic topographies at the surface and at the CMB and the geoid are calculated as well. Within the range of viscosity profiles allowing for a satisfying restitution of the long wavelength geoid, we perform a parametric study to decipher the role of the characteristics of phase diagrams - mainly the Clapeyron's slopes - and of the kinetics of phase transitions, which may modify phase transition topographies. Indeed, when a phase transition is delayed, the boundary between two mineral phases is both dragged by the flow and interfere with it. The results are compared to recent estimations of surface dynamic topography and to the phase transition topographies as revealed by seismic studies. The consequences are then discussed in terms of structure of mantle flow. Comparisons between various tomographic models allow us to enlighten the most robust features. At last, the role played by the phase transitions on the lateral variations of mass transfer between upper and lower mantle are quantified by comparison to cases with no phase transitions and confronted to regional tomographic models, which reflect the variability of the behaviors of the descending slabs in the transition zone.

Comparison of a direct-reading device to gravimetric methods for evaluating organic dust aerosols in an enclosed swine production environment.

Science.gov (United States)

Taylor, C D; Reynolds, S J

2001-01-01

The production of livestock in enclosed facilities has become an accepted practice, driven by the need for increased efficiency. Exposure to organic dusts, containing various bioactive components, has been identified an important risk factor for the high rate of lung disease found among workers in these environments. Assessment of organic dust exposure requires technical skills and instrumentation not readily available to most agricultural enterprises. Development of a simple, cost-effective method for measuring organic dust levels would be useful in evaluating and controlling exposures in these environments. The objective of this study was to evaluate the usefulness of the direct reading MIE PDM-3 Miniram for estimating organic dust concentrations in enclosed swine production facilities. Responses from the MIE PDM-3 Miniram were compared to gravimetric methods for total and inhalable dust. Total dust determinations were conducted in accordance with the National Institute for Occupational Safety and Health (NIOSH) method 0500. Inhalable particulate mass (IPM) sampling was conducted using SKC brand IOM (Institute of Occupational Medicine) sampling cassettes, which meet the American Conference of Governmental Industrial Hygienists ACGIH criteria for inhalable dust sampling. This study design also allowed for the comparison of traditional total dust method to the IPM method, in collecting organic dusts in an agricultural setting. Fifteen sets of side-by-side samples (Miniram, total dust, and IPM) were collected over a period of six months in a swine confinement building. There were statistically significant differences in the results provided by the three sampling methods. Measurements for inhalable dust exceeded those for total dust in eleven of fifteen samples. The Miniram time-weighted average (TWA) response to the organic dust was always the lower of the three methods. A high degree of correlation was found among all three methods. The Miniram performed well under

Determination of normal heights in the area of Polish Economic Zone

Directory of Open Access Journals (Sweden)

Jerzy B. Rogowski

2017-12-01

Full Text Available The article presents a method of determining the level of the seabed in the Polish reference system. The authors show how to determine the ellipsoidal height of the seabed using GNSS measurements and single-beam echo sounders. The authors propose the transition to the system of normal heights referred to the average level of the North Sea as defined by the tide-gauge in Amsterdam to be made using the EGM 2008 model and data from the official Polish quasi-geoid model as well as data from another model distributed by GUGiK (Head Office of Geodesy and Cartography. The article presents also potential errors of the presented method.

2017 Updates: Earth Gravitational Model 2020

Science.gov (United States)

Barnes, D. E.; Holmes, S. A.; Ingalls, S.; Beale, J.; Presicci, M. R.; Minter, C.

2017-12-01

The National Geospatial-Intelligence Agency [NGA], in conjunction with its U.S. and international partners, has begun preliminary work on its next Earth Gravitational Model, to replace EGM2008. The new `Earth Gravitational Model 2020' [EGM2020] has an expected public release date of 2020, and will retain the same harmonic basis and resolution as EGM2008. As such, EGM2020 will be essentially an ellipsoidal harmonic model up to degree (n) and order (m) 2159, but will be released as a spherical harmonic model to degree 2190 and order 2159. EGM2020 will benefit from new data sources and procedures. Updated satellite gravity information from the GOCE and GRACE mission, will better support the lower harmonics, globally. Multiple new acquisitions (terrestrial, airborne and shipborne) of gravimetric data over specific geographical areas (Antarctica, Greenland …), will provide improved global coverage and resolution over the land, as well as for coastal and some ocean areas. Ongoing accumulation of satellite altimetry data as well as improvements in the treatment of this data, will better define the marine gravity field, most notably in polar and near-coastal regions. NGA and partners are evaluating different approaches for optimally combining the new GOCE/GRACE satellite gravity models with the terrestrial data. These include the latest methods employing a full covariance adjustment. NGA is also working to assess systematically the quality of its entire gravimetry database, towards correcting biases and other egregious errors. Public release number 15-564

Cell design concepts for aqueous lithium-oxygen batteries: A model-based assessment

Science.gov (United States)

Grübl, Daniel; Bessler, Wolfgang G.

2015-11-01

Seven cell design concepts for aqueous (alkaline) lithium-oxygen batteries are investigated using a multi-physics continuum model for predicting cell behavior and performance in terms of the specific energy and specific power. Two different silver-based cathode designs (a gas diffusion electrode and a flooded cathode) and three different separator designs (a porous separator, a stirred separator chamber, and a redox-flow separator) are compared. Cathode and separator thicknesses are varied over a wide range (50 μm-20 mm) in order to identify optimum configurations. All designs show a considerable capacity-rate effect due to spatiotemporally inhomogeneous precipitation of solid discharge product LiOH·H2O. In addition, a cell design with flooded cathode and redox-flow separator including oxygen uptake within the external tank is suggested. For this design, the model predicts specific power up to 33 W/kg and specific energy up to 570 Wh/kg (gravimetric values of discharged cell including all cell components and catholyte except housing and piping).

Adsorption characteristics of methane on Maxsorb III by gravimetric method

KAUST Repository

Thu, Kyaw

2014-11-01

Adsorption characteristics of CH4 on the carbonaceous porous material is evaluated for possible application in adsorbed natural gas (ANG) system. Adsorption uptakes at assorted temperatures (25-80 °C) and pressures ranging from ambient to relatively high pressure i.e., 8.0 MPa are experimentally investigated. Surface characteristics such as pore surface area, micropore volume and pore size distribution of the adsorbent (Maxsorb III) are first evaluated using Classical Volumetric Method i.e., the manometric method with N2 gas adsorption at 77 K. The sorption measurements for methane, CH4 gas are carried out by thermogravimetric (TGA) method using magnetic suspension balance coupled with the automatic dosing system. The buoyancy measurements were first conducted using Helium gas as adsorbate. Buoyancy correction is applied to all sets of measured data and the specific uptake capacities (g/g of adsorbent) at various temperatures and pressures were calculated. The isotherm data were then fitted using Langmuir and Tòth isotherm models. It is observed that the data can be satisfactorily fitted using Tòth model with excellent fitting accuracy around 2.2% within the experimental range. The outcome of the present study especially the adsorption data at high pressures is applicable to accurate design and modeling of Adsorbed Natural Gas (ANG) systems. © 2014 Elsevier Ltd. All rights reserved.

Laboratory Evaluation of Light Obscuration Particle Counter Contamination Limits for Aviation Fuel

Science.gov (United States)

2015-11-01

assurance testing though conducting periodic fuel sampling for gravimetric analysis. The Army currently utilizes two methods for measuring particulate...contamination by gravimetric analysis: ASTM D2276 - Standard Test Method for Particulate Contaminant in Aviation Fuel by Line Sampling, and ASTM D5452...while filter effectiveness is checked every 30 days by gravimetric analysis (ASTM D2276). One of the problems with the gravimetric methods is the

Laboratory Evaluation of Light Obscuration Particle Counters used to Establish use Limits for Aviation Fuel

Science.gov (United States)

2015-12-01

The Army currently utilizes two methods for measuring particulate contamination by gravimetric analysis: ASTM D2276 - Standard Test Method for...is checked every 30 days by gravimetric analysis (ASTM D2276). One of the problems with the gravimetric methods is the poor repeatability and...ASTM D2276 testing is an artifact of that method . The correlation of particle counter data to the theoretical gravimetric concentration, and cross

Gravity anomalies, compensation mechanisms, and the geodynamics of western Ishtar Terra, Venus

Science.gov (United States)

Grimm, Robert E.; Phillips, Roger J.

1991-01-01

Pioneer Venus line-of-sight orbital accelerations were utilized to calculate the geoid and vertical gravity anomalies for western Ishtar Terra on various planes of altitude z sub 0. The apparent depth of isostatic compensation at z sub 0 = 1400 km is 180 + or - 20 km based on the usual method of minimum variance in the isostatic anomaly. An attempt is made here to explain this observation, as well as the regional elevation, peripheral mountain belts, and inferred age of western Ishtar Terra, in terms of one or three broad geodynamic models.

Gravity and low-frequency geodynamics

CERN Document Server

Teisseyre, Roman

1989-01-01

This fourth volume in the series Physics and Evolution of the Earth's Interior, provides a comprehensive review of the geophysical and geodetical aspects related to gravity and low-frequency geodynamics. Such aspects include the Earth's gravity field, geoid shape theory, and low-frequency phenomena like rotation, oscillations and tides.Global-scale phenomena are treated as a response to source excitation in spherical Earth models consisting of several shells: lithosphere, mantle, core and sometimes also the inner solid core. The effect of gravitation and rotation on the Earth's shape is anal

Validation of Mean Absolute Sea Level of the North Atlantic obtained from Drifter, Altimetry and Wind Data

Science.gov (United States)

Maximenko, Nikolai A.

2003-01-01

Mean absolute sea level reflects the deviation of the Ocean surface from geoid due to the ocean currents and is an important characteristic of the dynamical state of the ocean. Values of its spatial variations (order of 1 m) are generally much smaller than deviations of the geoid shape from ellipsoid (order of 100 m) that makes the derivation of the absolute mean sea level a difficult task for gravity and satellite altimetry observations. Technique used by Niiler et al. for computation of the absolute mean sea level in the Kuroshio Extension was then developed into more general method and applied by Niiler et al. (2003b) to the global Ocean. The method is based on the consideration of balance of horizontal momentum.

Comment on "An Assessment of the ICE-6G_C (VM5a) Glacial Isostatic Adjustment Model" by Purcell et al.

Science.gov (United States)

Richard Peltier, W.; Argus, Donald F.; Drummond, Rosemarie

2018-02-01

The most recently published model of the glacial isostatic adjustment process in the ICE-NG (VMX) sequence from the University of Toronto, denoted ICE-6G_C (VM5a), was originally developed to degree and order 256 in spherical harmonics and has been shown to provide accurate fits to a voluminous database of GPS observations from North America, Eurasia, and Antarctica, to time dependent gravity data being provided by the GRACE satellites, and to radiocarbon-dated relative sea level histories through the Holocene epoch. The authors of the Purcell et al. (2016, https://doi.org/10.1002/2015JB012742) paper have suggested this model to be flawed. We have produced a further version of our model, denoted ICE-6G_D (VM5a), by employing the same BEDMAP2 bathymetry for the Southern Ocean as employed in their analysis which has somewhat reduced the differences between our results. However, significant physically important differences remain, including the magnitude of present-day vertical crustal motion in the embayments and in the spectrum of Stokes coefficients for present-day geoid height time dependence which continues to "flatten" at high spherical harmonic degree. We explore the reasons for these differences and trace them to the use by Purcell et al. of a loading history for the embayments that differs significantly from that tabulated for both the original and modified versions of our model.

Site selection methods for nuclear waste storage in sub-schistic granites

International Nuclear Information System (INIS)

Alsac, C.; Chantraine, J.; Chevremont, P.

1984-02-01

Intrusive granites in schists, where most of the roof is at a depth of several hundred metres can be regarded as favourable sites for storing radioactive waste since the schistic cover has extremely low permeability. This configuration exists in various parts of France. In this paper the authors describe methods which can be applied to the study of such structures, taking a region in the Armorican Massif as a reference example. The geological evidence here showed an extensive zone with a slight gravimetric anomaly around a few granite outcrops dispersed in the schists. This structure gave reason to believe that a shallow granite mass would be found under the schistic cover, and geological and gravimetric surface studies did indeed prove that this supposition was correct. Apart from the slight gravimetric anomaly, the extent of which has been confirmed and the outlines determined, the transformations (contact metamorphism and hydrothermalism) of the enclosing schists are particularly indicative of the presence of granite. The gravimetric model shows that the thickness of the granite is at least 2.3 km and provides an initial representation of the shape and depth of the roof. These results, together with those of the structural analysis, can be used to demarcate a favourable region for investigations at depth which will make it possible: to monitor the geological structures; to define the geotechnical characteristics of the formations; to analyse and model the hydrogeological behaviour, at present known only from surface studies which do not appear to indicate any circulation of water upwards towards the surface

Modeling multidomain hydraulic properties of shrink-swell soils

Science.gov (United States)

Stewart, Ryan D.; Abou Najm, Majdi R.; Rupp, David E.; Selker, John S.

2016-10-01

Shrink-swell soils crack and become compacted as they dry, changing properties such as bulk density and hydraulic conductivity. Multidomain models divide soil into independent realms that allow soil cracks to be incorporated into classical flow and transport models. Incongruously, most applications of multidomain models assume that the porosity distributions, bulk density, and effective saturated hydraulic conductivity of the soil are constant. This study builds on a recently derived soil shrinkage model to develop a new multidomain, dual-permeability model that can accurately predict variations in soil hydraulic properties due to dynamic changes in crack size and connectivity. The model only requires estimates of soil gravimetric water content and a minimal set of parameters, all of which can be determined using laboratory and/or field measurements. We apply the model to eight clayey soils, and demonstrate its ability to quantify variations in volumetric water content (as can be determined during measurement of a soil water characteristic curve) and transient saturated hydraulic conductivity, Ks (as can be measured using infiltration tests). The proposed model is able to capture observed variations in Ks of one to more than two orders of magnitude. In contrast, other dual-permeability models assume that Ks is constant, resulting in the potential for large error when predicting water movement through shrink-swell soils. Overall, the multidomain model presented here successfully quantifies fluctuations in the hydraulic properties of shrink-swell soil matrices, and are suitable for use in physical flow and transport models based on Darcy's Law, the Richards Equation, and the advection-dispersion equation.

Sea Surface Height Deviation, Aviso, 0.25 degrees, Global, Science Quality

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Aviso Sea Surface Height Deviation is the deviation from the mean geoid as measured from 1993 - 1995. This is Science Quality data.

Airborne gravity tests in the Italian area to improve the geoid model of Italy

DEFF Research Database (Denmark)

Barzaghi, R; Borghi, A; Keller, K

2009-01-01

Airborne gravimetry is an important method for measuring gravity over large unsurveyed areas. This technology has been widely applied in Canada, Antarctica and Greenland to map the gravity fields of these regions and in recent years, in the oil industry. In 2005, two tests in the Italian area were...... performed by ENI in cooperation with the Politecnico di Milano and the Danish National Space Center. To the knowledge of the authors, these were the first experiments of this kind in Italy and were performed over the Ionian coasts of Calabria and the Maiella Mountains. The Calabria test field......, the collocation method applied to compare and merge ground-based and airborne data proved to be efficient and reliable. The standard deviation of the discrepancies between airborne data and collocation upward continued gravity is, in both cases, less than 8 mgal. In the Maiella test, the gravity field obtained...

A Global Ocean Tide Model From TOPEX/POSEIDON Altimetry: GOT99.2

Science.gov (United States)

Ray, Richard D.

1999-01-01

Goddard Ocean Tide model GOT99.2 is a new solution for the amplitudes and phases of the global oceanic tides, based on over six years of sea-surface height measurements by the TOPEX/POSEIDON satellite altimeter. Comparison with deep-ocean tide-gauge measurements show that this new tidal solution is an improvement over previous global models, with accuracies for the main semidiurnal lunar constituent M2 now below 1.5 cm (deep water only). The new solution benefits from use of prior hydrodynamic models, several in shallow and inland seas as well as the global finite-element model FES94.1. This report describes some of the data processing details involved in handling the altimetry, and it provides a comprehensive set of global cotidal charts of the resulting solutions. Various derived tidal charts are also provided, including tidal loading deformation charts, tidal gravimetric charts, and tidal current velocity (or transport) charts. Finally, low-degree spherical harmonic coefficients are computed by numerical quadrature and are tabulated for the major short-period tides; these are useful for a variety of geodetic and geophysical purposes, especially in combination with similar estimates from satellite laser ranging.

A high-order 3-D spectral-element method for the forward modelling and inversion of gravimetric data—Application to the western Pyrenees

Science.gov (United States)

Martin, Roland; Chevrot, Sébastien; Komatitsch, Dimitri; Seoane, Lucia; Spangenberg, Hannah; Wang, Yi; Dufréchou, Grégory; Bonvalot, Sylvain; Bruinsma, Sean

2017-04-01

We image the internal density structure of the Pyrenees by inverting gravity data using an a priori density model derived by scaling a Vp model obtained by full waveform inversion of teleseismic P-waves. Gravity anomalies are computed via a 3-D high-order finite-element integration in the same high-order spectral-element grid as the one used to solve the wave equation and thus to obtain the velocity model. The curvature of the Earth and surface topography are taken into account in order to obtain a density model as accurate as possible. The method is validated through comparisons with exact semi-analytical solutions. We show that the spectral-element method drastically accelerates the computations when compared to other more classical methods. Different scaling relations between compressional velocity and density are tested, and the Nafe-Drake relation is the one that leads to the best agreement between computed and observed gravity anomalies. Gravity data inversion is then performed and the results allow us to put more constraints on the density structure of the shallow crust and on the deep architecture of the mountain range.

Application of GPS in a high precision engineering survey network

International Nuclear Information System (INIS)

Ruland, R.; Leick, A.

1985-04-01

A GPS satellite survey was carried out with the Macrometer to support construction at the Stanford Linear Accelerator Center (SLAC). The network consists of 16 stations of which 9 stations were part of the Macrometer network. The horizontal and vertical accuracy of the GPS survey is estimated to be 1 to 2 mm and 2 to 3 mm respectively. The horizontal accuracy of the terrestrial survey, consisting of angles and distances, equals that of the GPS survey only in the ''loop'' portion of the network. All stations are part of a precise level network. The ellipsoidal heights obtained from the GPS survey and the orthometric heights of the level network are used to compute geoid undulations. A geoid profile along the linac was computed by the National Geodetic Survey in 1963. This profile agreed with the observed geoid within the standard deviation of the GPS survey. Angles and distances were adjusted together (TERRA), and all terrestrial observations were combined with the GPS vector observations in a combination adjustment (COMB). A comparison of COMB and TERRA revealed systematic errors in the terrestrial solution. A scale factor of 1.5 ppM +- .8 ppM was estimated. This value is of the same magnitude as the over-all horizontal accuracy of both networks. 10 refs., 3 figs., 5 tabs

3-D crustal-scale gravity model of the San Rafael Block and Payenia volcanic province in Mendoza, Argentina

Directory of Open Access Journals (Sweden)

Daniel Richarte

2018-01-01

Based on gravimetric and magnetic data, together with isostatic and elastic thickness analyses, we modeled the crustal structure of the area. Information obtained has allowed us to understand the crust where the SRB and the Payenia volcanic province are located. Bouguer anomalies indicate that the SRB presents higher densities to the North of Cerro Nevado and Moho calculations suggest depths for this block between 40 and 50 km. Determinations of elastic thickness would indicate that the crust supporting the San Rafael Block presents values of approximately 10 km, being enough to support the block loading. However, in the Payenia region, elastic thickness values are close to zero due to the regional temperature increase.

GEOSAT 44: High-Accuracy, High-Resolution Gravity

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This satellite altimeter data base contains precise geoid and gravity anomaly profiles which were constructed from the average of 44 repeat cycles of Geosat. The...

AVISO_L4_DYN_TOPO_1DEG_1MO:1

Data.gov (United States)

National Aeronautics and Space Administration — The absolute dynamic topography data (similar to sea level but with respect to the geoid) are on monthly 1 degree grids. These data were generated to help support...

PODAAC-DYNTO-1D1M1

Data.gov (United States)

National Aeronautics and Space Administration — The absolute dynamic topography data (similar to sea level but with respect to the geoid) are on monthly 1 degree grids. These data were generated to help support...

GEOSAT44: High-Accuracy, High-Resolution Gravity

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This satellite altimeter data base contains precise geoid and gravity anomaly profiles which were constructed from the average of 44 repeat cycles of Geosat. The...

40 CFR 610.64 - Track test procedures.

Science.gov (United States)

2010-07-01

... truck or trailer. (4) Fuel economy will be determined by either a gravimetric or volumetric method. (c... dynamometer except that fuel economy will be measured by gravimetric or volumetric methods. ... either a volumetric or gravimetric procedure approved by the Administrator. (5) Vehicle speed and...

Improved High Resolution Models of Subduction Dynamics: Use of transversely isotropic viscosity with a free-surface

Science.gov (United States)

Liu, X.; Gurnis, M.; Stadler, G.; Rudi, J.; Ratnaswamy, V.; Ghattas, O.

2017-12-01

Dynamic topography, or uncompensated topography, is controlled by internal dynamics, and provide constraints on the buoyancy structure and rheological parameters in the mantle. Compared with other surface manifestations such as the geoid, dynamic topography is very sensitive to shallower and more regional mantle structure. For example, the significant dynamic topography above the subduction zone potentially provides a rich mine for inferring the rheological and mechanical properties such as plate coupling, flow, and lateral viscosity variations, all critical in plate tectonics. However, employing subduction zone topography in the inversion study requires that we have a better understanding of the topography from forward models, especially the influence of the viscosity formulation, numerical resolution, and other factors. One common approach to formulating a fault between the subducted slab and the overriding plates in viscous flow models assumes a thin weak zone. However, due to the large lateral variation in viscosity, topography from free-slip numerical models typically has artificially large magnitude as well as high-frequency undulations over subduction zone, which adds to the difficulty in making comparisons between model results and observations. In this study, we formulate a weak zone with the transversely isotropic viscosity (TI) where the tangential viscosity is much smaller than the viscosity in the normal direction. Similar with isotropic weak zone models, TI models effectively decouple subducted slabs from the overriding plates. However, we find that the topography in TI models is largely reduced compared with that in weak zone models assuming an isotropic viscosity. Moreover, the artificial `tooth paste' squeezing effect observed in isotropic weak zone models vanishes in TI models, although the difference becomes less significant when the dip angle is small. We also implement a free-surface condition in our numerical models, which has a smoothing

Effect of the lithospheric thermal state on the Moho interface: A case study in South America

Science.gov (United States)

Bagherbandi, Mohammad; Bai, Yongliang; Sjöberg, Lars E.; Tenzer, Robert; Abrehdary, Majid; Miranda, Silvia; Alcacer Sanchez, Juan M.

2017-07-01

Gravimetric methods applied for Moho recovery in areas with sparse and irregular distribution of seismic data often assume only a constant crustal density. Results of latest studies, however, indicate that corrections for crustal density heterogeneities could improve the gravimetric result, especially in regions with a complex geologic/tectonic structure. Moreover, the isostatic mass balance reflects also the density structure within the lithosphere. The gravimetric methods should therefore incorporate an additional correction for the lithospheric mantle as well as deeper mantle density heterogeneities. Following this principle, we solve the Vening Meinesz-Moritz (VMM) inverse problem of isostasy constrained by seismic data to determine the Moho depth of the South American tectonic plate including surrounding oceans, while taking into consideration the crustal and mantle density heterogeneities. Our numerical result confirms that contribution of sediments significantly modifies the estimation of the Moho geometry especially along the continental margins with large sediment deposits. To account for the mantle density heterogeneities we develop and apply a method in order to correct the Moho geometry for the contribution of the lithospheric thermal state (i.e., the lithospheric thermal-pressure correction). In addition, the misfit between the isostatic and seismic Moho models, attributed mainly to deep mantle density heterogeneities and other geophysical phenomena, is corrected for by applying the non-isostatic correction. The results reveal that the application of the lithospheric thermal-pressure correction improves the RMS fit of the VMM gravimetric Moho solution to the CRUST1.0 (improves ∼ 1.9 km) and GEMMA (∼1.1 km) models and the point-wise seismic data (∼0.7 km) in South America.

An application of the geophysical methods and ALS DTM for the identification of the geological structure in the Kraśnik region - Lublin Upland, Poland

Science.gov (United States)

Kamiński, Mirosław

2017-11-01

The purpose of the study was the assessment of the viability of selected geophysical methods and the Airborne Laser Scanning (ALS) for the identification and interpretation of the geological structure. The studied area is covered with a dense forest. For this reason, the ALS numerical terrain model was applied for the analysis of the topography. Three geophysical methods were used: gravimetric, in the form of a semi-detailed gravimetric photograph, Vertical Electrical Sounding (VES), and Electrical Resistivity Tomography (ERT). The numerical terrain model enabled the identification of Jurassic limestone outcrops and interpretation of the directions of the faults network. The geological interpretation of the digitally processed gravimetric data enabled the determination of the spatial orientation of the synclines and anticlines axes and of the course directions of main faults. Vertical Electrical Sounding carried along the section line perpendicular to the Gościeradów anticline axis enabled the interpretation of the lithology of this structure and identification of its complex tectonic structure. The shallow geophysical surveys using the ERT method enabled the estimation of the thickness of Quaternary formations deposited unconformably on the highly eroded Jurassic limestone outcrop. The lithology of Quaternary, Cretaceous and Jurassic rocks was also interpreted.

An application of the geophysical methods and ALS DTM for the identification of the geological structure in the Kraśnik region – Lublin Upland, Poland

Directory of Open Access Journals (Sweden)

Kamiński Mirosław

2017-01-01

Full Text Available The purpose of the study was the assessment of the viability of selected geophysical methods and the Airborne Laser Scanning (ALS for the identification and interpretation of the geological structure. The studied area is covered with a dense forest. For this reason, the ALS numerical terrain model was applied for the analysis of the topography. Three geophysical methods were used: gravimetric, in the form of a semi-detailed gravimetric photograph, Vertical Electrical Sounding (VES, and Electrical Resistivity Tomography (ERT. The numerical terrain model enabled the identification of Jurassic limestone outcrops and interpretation of the directions of the faults network. The geological interpretation of the digitally processed gravimetric data enabled the determination of the spatial orientation of the synclines and anticlines axes and of the course directions of main faults. Vertical Electrical Sounding carried along the section line perpendicular to the Gościeradów anticline axis enabled the interpretation of the lithology of this structure and identification of its complex tectonic structure. The shallow geophysical surveys using the ERT method enabled the estimation of the thickness of Quaternary formations deposited unconformably on the highly eroded Jurassic limestone outcrop. The lithology of Quaternary, Cretaceous and Jurassic rocks was also interpreted.

Results precision gravimetric picture for construction of wind generators; Точность результатов гравиметрического изображения для строительства ветряных генераторов

Energy Technology Data Exchange (ETDEWEB)

Tsenkov, T. [Higher School of Civil Engineering ' Lyuben Karavelov' , Sofia (Bulgaria); Mihaylov, E. [National Institute of Geophysics, Geodesy and Geography, Bulgarian Academy of Sciences, Sofia (Bulgaria)

2012-07-01

The outcome of the high precision gravimetric picture near the town of Shabla made maps of anomalies Bugei, average anomalies, residual / local / anomalies and average horizontal gradients, indicating stability in the region of the image in geological and hydrogeological terms for construction of wind generators. (author)

Matlab script for 3D visualizing geodata on a rotating globe

Czech Academy of Sciences Publication Activity Database

Bezděk, Aleš; Sebera, Josef

2013-01-01

Roč. 56, July (2013), s. 127-130 ISSN 0098-3004 Institutional support: RVO:67985815 Keywords : 3D visualization * geoid height * elevation mode Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 1.562, year: 2013

Amorphous MoS₃ Infiltrated with Carbon Nanotubes as an Advanced Anode Material of Sodium-Ion Batteries with Large Gravimetric, Areal, and Volumetric Capacities

Energy Technology Data Exchange (ETDEWEB)

Ye, Hualin [Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 China; Wang, Lu [Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 China; Deng, Shuo [Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 China; Zeng, Xiaoqiao [Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont IL 60439 USA; Nie, Kaiqi [Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 China; Duchesne, Paul N. [Department of Chemistry, Dalhousie University, Halifax NS B3H 4R2 Canada; Wang, Bo [Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 China; Liu, Simon [Department of Chemical Engineering, University of Waterloo, Ontario N2L 3G1 Canada; Zhou, Junhua [Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 China; Zhao, Feipeng [Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 China; Han, Na [Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 China; Zhang, Peng [Department of Chemistry, Dalhousie University, Halifax NS B3H 4R2 Canada; Zhong, Jun [Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 China; Sun, Xuhui [Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 China; Li, Youyong [Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 China; Li, Yanguang [Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 China; Lu, Jun [Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont IL 60439 USA

2016-11-17

The search for earth-abundant and high-performance electrode materials for sodium-ion batteries represents an important challenge to current battery research. 2D transition metal dichalcogenides, particularly MoS2, have attracted increasing attention recently, but few of them so far have been able to meet expectations. In this study, it is demonstrated that another phase of molybdenum sulfide—amorphous chain-like MoS3—can be a better choice as the anode material of sodium-ion batteries. Highly compact MoS3 particles infiltrated with carbon nanotubes are prepared via the facile acid precipitation method in ethylene glycol. Compared to crystalline MoS2, the resultant amorphous MoS3 not only exhibits impressive gravimetric performance—featuring excellent specific capacity (≈615 mA h g-1), rate capability (235 mA h g-1 at 20 A g-1), and cycling stability but also shows exceptional volumetric capacity of ≈1000 mA h cm-3 and an areal capacity of >6.0 mA h cm-2 at very high areal loadings of active materials (up to 12 mg cm-2). The experimental results are supported by density functional theory simulations showing that the 1D chains of MoS3 can facilitate the adsorption and diffusion of Na+ ions. At last, it is demonstrated that the MoS3 anode can be paired with an Na3V2(PO4)3 cathode to afford full cells with great capacity and cycling performance.

Inner structure of the Puy de Dôme volcano: cross-comparison of geophysical models (ERT, gravimetry, muon imaging

Directory of Open Access Journals (Sweden)

A. Portal

2013-01-01

Full Text Available Muon imaging of volcanoes and of geological structures in general is actively being developed by several groups in the world. It has the potential to provide 3-D density distributions with an accuracy of a few percent. At this stage of development, comparisons with established geophysical methods are useful to validate the method. An experiment has been carried out in 2011 and 2012 on a large trachytic dome, the Puy de Dôme volcano, to perform such a comparison of muon imaging with gravimetric tomography and 2-D electrical resistivity tomography. Here, we present the preliminary results for the last two methods. North–south and east–west resistivity profiles allow us to model the resistivity distribution down to the base of the dome. The modelling of the Bouguer anomaly provides models for the density distribution within the dome that are directly comparable with the results from the muon imaging. Our ultimate goal is to derive a model of the dome using the joint interpretation of all sets of data.

Studies on Fragrance Delivery from Inorganic Nanocontainers: Encapsulation, Release and Modeling Studies

Science.gov (United States)

Ghodke, Shailesh Adinath; Sonawane, Shirish Hari; Bhanvase, Bharat Apparao; Mishra, Satyendra; Joshi, Kalpana Shrikant

2015-04-01

The present work deals with encapsulation of fragrance molecule in inorganic nanocontainers substrate and investigation of its prolonged release at different pH condition. The nanocontainers used were aluminosilicate clay (Halloysite) having cylindrical shape with outside diameter in the range of 30-50 nm, 15 nm lumen and length equal to 800 ± 300 nm. Rosewater absolute was used as a sample fragrance for loading in nanocontainer and delivery purpose. The fragrance loaded nanocontainers were coated with a thin layer of polyelectrolyte i.e. Polyacrylic Acid (PAA). The structural characteristics of prepared nanocontainers were determined by using Fourier Transform Intra-red Spectroscopy (FTIR), Thermal Gravimetric Analysis (TGA) and UV spectroscopy analysis. Release of fragrance molecules in the aqueous medium was monitored for 24 h. The fragrance release was found to be responsive as the amount of fragrance release increases with increase in pH value from 3 to 7. Fragrance release has been studied by using various permeation kinetic models such as zero order, first order, Hixson-Crowell, Higuchi, Korsmeyer-Peppas and Hopfenberg models. Korsemyer-Peppas shows the best fit (R2 = 0.9544) compared to other kinetic model for the release of fragrance from nanocontainers.

Adsorption of 1,2-dichlorobenzene and 1,2,4-trichlorobenzene in nano- and microsized crystals of MIL-101(Cr): static and dynamic gravimetric studies.

Science.gov (United States)

Bullot, Laetitia; Vieira-Sellaï, Ludivine; Chaplais, Gérald; Simon-Masseron, Angélique; Daou, Toufic Jean; Patarin, Joël; Fiani, Emmanuel

2017-12-01

This work aims to highlight the promising adsorption capacity and kinetic of (poly)chlorobenzene pollutants in the hybrid MIL-101(Cr) type material for technological uses in industrial waste exhaust decontamination. The influence of the MIL-101(Cr) crystal size (nano- and microcrystals) on the adsorption behavior was studied in static and dynamic modes. For this purpose, crystals of MIL-101(Cr) in nano- and micrometric sizes were synthesized and fully characterized. Their sorption properties regarding 1,2-dichlorobenzene were examined using gravimetric method in dynamic (p/p° = 0.5) and static (p/p° = 1) modes at room temperature. 1,2,4-trichlorobenzene adsorption was only performed under static mode because of its too low vapor pressure. 1,2-dichlorobenzene and 1,2,4-trichlorobenzene were used to mimic 2,3-dichlorodibenzo-p-dioxin and 1,2,3,4-tetrachlorodibenzo-p-dioxin, respectively, and more largely dioxin compounds. Adsorptions of these probes were successfully carried out in nano- and microcrystals of MIL-101(Cr). Indeed, in static mode (p/p° = 1) and at room temperature, nanocrystals adsorb 2266 molecules of 1,2-dichlorobenzene and 2093 molecules of 1,2,4-trichlorobenzene per unit cell, whereas microcrystals adsorb 1871 molecules of 1,2-dichlorobenzene and 1631 molecules of 1,2,4-trichlorobenzene per unit cell. In dynamic mode, the 1,2-dichlorobenzene adsorbed amounts are substantially similar to those obtained in static mode. However, the adsorption kinetics are different because of a different scheme of diffusivity of the adsorbate between the two modes. To the best of our knowledge, these adsorption capacities of MIL-101(Cr) as adsorbent for polychlorobenzenes trapping have never been referenced. MIL-101(Cr) appears as a promising material for technological uses in industrial waste exhaust decontamination.

An Investigation on the Use of Different Centroiding Algorithms and Star Catalogs in Astro-Geodetic Observations

Science.gov (United States)

Basoglu, Burak; Halicioglu, Kerem; Albayrak, Muge; Ulug, Rasit; Tevfik Ozludemir, M.; Deniz, Rasim

2017-04-01

In the last decade, the importance of high-precise geoid determination at local or national level has been pointed out by Turkish National Geodesy Commission. The Commission has also put objective of modernization of national height system of Turkey to the agenda. Meanwhile several projects have been realized in recent years. In Istanbul city, a GNSS/Levelling geoid was defined in 2005 for the metropolitan area of the city with an accuracy of ±3.5cm. In order to achieve a better accuracy in this area, "Local Geoid Determination with Integration of GNSS/Levelling and Astro-Geodetic Data" project has been conducted in Istanbul Technical University and Bogazici University KOERI since January 2016. The project is funded by The Scientific and Technological Research Council of Turkey. With the scope of the project, modernization studies of Digital Zenith Camera System are being carried on in terms of hardware components and software development. Accentuated subjects are the star catalogues, and centroiding algorithm used to identify the stars on the zenithal star field. During the test observations of Digital Zenith Camera System performed between 2013-2016, final results were calculated using the PSF method for star centroiding, and the second USNO CCD Astrograph Catalogue (UCAC2) for the reference star positions. This study aims to investigate the position accuracy of the star images by comparing different centroiding algorithms and available star catalogs used in astro-geodetic observations conducted with the digital zenith camera system.

1-deg x 1-deg Terrestrial Mean Free-Air Anomalies

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The 1x1 degree Terrestrial Mean Free-Air Gravity Anomaly and Geoid Undulations Data Base was compiled and developed by the Ohio State University. This data base was...

30-min x 30-min Terrestrial Mean Free-Air Anomalies

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The 30-min x 30-min Terrestrial Mean Free-Air Gravity Anomaly and Geoid Undulations Data Base was compiled and developed by the Ohio State University. This data base...

Kinetics of methanol decomposition on Cu/ZnO/ZrO2 catalysts

International Nuclear Information System (INIS)

Grabowski, R.; Kozlowska, A.

2004-01-01

Interaction of methanol with Cu/ZnO/ZrO 2 (with different copper content) has been investigated by gravimetric and TPD methods. The TPD measurements of methanol adsorption on these catalysis show that it forms the complexes of two types. The first complex (I) decomposes at low temperature (453 K) yielding H 2 and CO 2 and second (II) decomposes at temperature (573 K) giving CO and H 2 . In the process of decomposition of the complex (I) takes part water which is adsorbed on the surface of the catalyst and the decomposition of the complex (II) occurs without participation of adsorbed water. Gravimetric measurements of methanol and that an increase of copper content leads to the changes in the kinetics of methanol adsorption and its decomposition. On the basis of gravimetric measurements a model of methanol adsorption and decomposition on Cu/ZnO/ZrO 2 catalyst has been proposed and the rate constants of methanol adsorption (k a ) and decomposition with and without participation of water (k 1 and k 2 ) have been determined. (author)

Moho Density Contrast in Central Eurasia from GOCE Gravity Gradients

Directory of Open Access Journals (Sweden)

Mehdi Eshagh

2016-05-01

Full Text Available Seismic data are primarily used in studies of the Earth’s inner structure. Since large parts of the world are not yet sufficiently covered by seismic surveys, products from the Earth’s satellite observation systems have more often been used for this purpose in recent years. In this study we use the gravity-gradient data derived from the Gravity field and steady-state Ocean Circulation Explorer (GOCE, the elevation data from the Shuttle Radar Topography Mission (SRTM and other global datasets to determine the Moho density contrast at the study area which comprises most of the Eurasian plate (including parts of surrounding continental and oceanic tectonic plates. A regional Moho recovery is realized by solving the Vening Meinesz-Moritz’s (VMM inverse problem of isostasy and a seismic crustal model is applied to constrain the gravimetric solution. Our results reveal that the Moho density contrast reaches minima along the mid-oceanic rift zones and maxima under the continental crust. This spatial pattern closely agrees with that seen in the CRUST1.0 seismic crustal model as well as in the KTH1.0 gravimetric-seismic Moho model. However, these results differ considerably from some previously published gravimetric studies. In particular, we demonstrate that there is no significant spatial correlation between the Moho density contrast and Moho deepening under major orogens of Himalaya and Tibet. In fact, the Moho density contrast under most of the continental crustal structure is typically much more uniform.

40 CFR 63.626 - Performance tests and compliance provisions.

Science.gov (United States)

2010-07-01

... Analysis For Phosphate Rock, No. 3 Phosphorus-P2O5 or Ca3(PO4)2, Method B—Gravimetric Quimociac Method. (D..., No. 3 Total Phosphorus-P2O5, Method B—Gravimetric Quimociac Method. (G) Section XI, Methods of..., Method B—Gravimetric Quimociac Method. (C) Section XI, Methods of Analysis For Phosphoric Acid...

An uncommon experience during removal of a foreign body from ear of a child

Directory of Open Access Journals (Sweden)

Sanjoy Kumar Ghosh

2016-04-01

Full Text Available A difficult to extract geoid bead was successfully removed from the middle ear cavity by threading it with monofilament polypropylene without drill-out of the bony annulus or widening the isthmus of the external auditory canal.

SPATIAL MODELLING FOR DESCRIBING SPATIAL VARIABILITY OF SOIL PHYSICAL PROPERTIES IN EASTERN CROATIA

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Igor Bogunović

2016-06-01

Full Text Available The objectives of this study were to characterize the field-scale spatial variability and test several interpolation methods to identify the best spatial predictor of penetration resistance (PR, bulk density (BD and gravimetric water content (GWC in the silty loam soil in Eastern Croatia. The measurements were made on a 25 x 25-m grid which created 40 individual grid cells. Soil properties were measured at the center of the grid cell deep 0-10 cm and 10-20 cm. Results demonstrated that PR and GWC displayed strong spatial dependence at 0-10 cm BD, while there was moderate and weak spatial dependence of PR, BD and GWC at depth of 10-20 cm. Semi-variogram analysis suggests that future sampling intervals for investigated parameters can be increased to 35 m in order to reduce research costs. Additionally, interpolation models recorded similar root mean square values with high predictive accuracy. Results suggest that investigated properties do not have uniform interpolation method implying the need for spatial modelling in the evaluation of these soil properties in Eastern Croatia.

Soft computing methods for geoidal height transformation

Science.gov (United States)

Akyilmaz, O.; Özlüdemir, M. T.; Ayan, T.; Çelik, R. N.

2009-07-01

Soft computing techniques, such as fuzzy logic and artificial neural network (ANN) approaches, have enabled researchers to create precise models for use in many scientific and engineering applications. Applications that can be employed in geodetic studies include the estimation of earth rotation parameters and the determination of mean sea level changes. Another important field of geodesy in which these computing techniques can be applied is geoidal height transformation. We report here our use of a conventional polynomial model, the Adaptive Network-based Fuzzy (or in some publications, Adaptive Neuro-Fuzzy) Inference System (ANFIS), an ANN and a modified ANN approach to approximate geoid heights. These approximation models have been tested on a number of test points. The results obtained through the transformation processes from ellipsoidal heights into local levelling heights have also been compared.

Desorption isotherms and mathematical modeling of thin layer drying kinetics of tomato

Science.gov (United States)

Belghith, Amira; Azzouz, Soufien; ElCafsi, Afif

2016-03-01

In recent years, there is an increased demand on the international market of dried fruits and vegetables with significant added value. Due to its important production, consumption and nutrient intake, drying of tomato has become a subject of extended and varied research works. The present work is focused on the drying behavior of thin-layer tomato and its mathematical modeling in order to optimize the drying processes. The moisture desorption isotherms of raw tomato were determined at four temperature levels namely 45, 50, 60 and 65 °C using the static gravimetric method. The experimental data obtained were modeled by five equations and the (GAB) model was found to be the best-describing these isotherms. The drying kinetics were experimentally investigated at 45, 55 and 65 °C and performed at air velocities of 0.5 and 2 m/s. In order to investigate the effect of the exchange surface on drying time, samples were dried into two different shapes: tomato halves and tomato quarters. The impact of various drying parameters was also studied (temperature, air velocity and air humidity). The drying curves showed only the preheating period and the falling drying rate period. In this study, attention was paid to the modeling of experimental thin-layer drying kinetics. The experimental results were fitted with four different models.

Modeling of Paleo Heat-and-Mass Trasport for Prognosys of Mineral Deposits Using GIS

International Nuclear Information System (INIS)

Cherkasov, Sergei; Vishnevskaya, Natalia; Cassard, Daniel; Sterligov, Boris; Arbuzova, Ekaterina

2008-01-01

The heat-and-mass flow from the mantle to the surface can be characterized by the three basic models. The first one represents just a convective heating of the crust by the hot mantle. Two other kinds of the heat-and-mass flow system are rather anomalous and sometimes serve as an engine for launching ore-forming processes. The second model describes a pipe-like conductive heat-and-flow system reasoning appearance of mafic-ultramafic intrusions coming to the surface directly from the upper mantle. The third model corresponds with a complicated convective-conductive process involving melting of crustal rocks, and forming magmatic chambers inside the crust. Analysis of gravimetric and seismic data using geographic informational systems allows us to locate elements of the anomalous heat-and-flow systems. Some of the elements (their projection on the surface) correlate with position of the known deposits of gold, silver, tungsten, tin, sometimes--molybdenum and base metals. The results of studies conducted by the Russian-French Metallogenic Laboratory in the frames of crystalline shields of Russia demonstrate location of 87% of the known gold-bearing deposits inside the zones defined by such analysis

Oceanic Loading Eect near the European Coast

Science.gov (United States)

Spiridonov, E.; Vinogradova, O.; Boyarskiy, E.; Afanasieva, L.

2012-04-01

The dissipation, anisotropy, and rotation constraints of the total oceanic gravimetric effect are analysed. The dependence of the results on the selected P- and S-velocity model (i.e., on the structure of the crust and upper mantle of the Earth) is considered. For calculating the effect of oceanic loading, we apply the method of Legendre polynomial expansion of tidal heights. The CSR3 model data are expanded up to the 720th order. The results yielded by this method closely agree with those calculated from the Green's functions by the LOAD07 program of the ETERNA software. Remarkable advantage of our program over other approaches is that it provides high-speed processing and does not require introducing the near-field formalism. Application of the pre-computed expansions reduces the time of calculations by two orders of magnitude, compared to LOAD07. This is particularly important when analyzing the geographical distributions of the loading effect predicted by different models. Taking dissipation into account improves the total gravimetric effect calculated for the M2 wave near the coast of Europe by 0.1-0.2 mcGal in amplitude and by a few hundredths of degree in phase. Transition from the PREM model to the IASP91 model which is better suitable for Europe changes the model predictions by 0.1-0.4 mcGal in amplitude and by 0.1 to 5-7 degrees in phase. Thus, allowance for dissipation together with the use of the refined data on the crustal and upper-mantle structure of the Earth may contribute, at places, over 0.5 mcGal to the amplitude and a few degrees to the phase of the total oceanic gravimetric effect. In this relation, particular attention should be paid to the regions about the Land's End cape (Cape Cornwall) and Cape Saint Mathieu.

Hydrogen storage in single-walled carbon nanotubes: methods and results

International Nuclear Information System (INIS)

Poirier, E.; Chahine, R.; Tessier, A.; Cossement, D.; Lafi, L.; Bose, T.K.

2004-01-01

We present high sensitivity gravimetric and volumetric hydrogen sorption measurement systems adapted for in situ conditioning under high temperature and high vacuum. These systems, which allow for precise measurements on small samples and thorough degassing, are used for sorption measurements on carbon nanostructures. We developed one volumetric system for the pressure range 0-1 bar, and two gravimetric systems for 0-1 bar and 0-100 bars. The use of both gravimetric and volumetric methods allows for the cross-checking of the results. The accuracy of the systems has been determined from hydrogen absorption measurements on palladium. The accuracies of the 0-1 bar volumetric and gravimetric systems are about 10 μg and 20 μg respectively. The accuracy of the 0-100 bars gravimetric system is about 20 μg. Hydrogen sorption measurements on single-walled carbon nanotubes (SWNTs) and metal-incorporated- SWNTs are presented. (author)

Coseismic and post-seismic signatures of the Sumatra 2004 December and 2005 March earthquakes in GRACE satellite gravity

Science.gov (United States)

Panet, I.; Mikhailov, V.; Diament, M.; Pollitz, F.; King, G.; de Viron, O.; Holschneider, M.; Biancale, R.; Lemoine, J.-M.

2007-01-01

The GRACE satellite mission has been measuring the Earth's gravity field and its temporal variations since 2002 April. Although these variations are mainly due to mass transfer within the geofluid envelops, they also result from mass displacements associated with phenomena including glacial isostatic adjustment and earthquakes. However, these last contributions are difficult to isolate because of the presence of noise and of geofluid signals, and because of GRACE's coarse spatial resolution (>400 km half-wavelength). In this paper, we show that a wavelet analysis on the sphere helps to retrieve earthquake signatures from GRACE geoid products. Using a wavelet analysis of GRACE geoids products, we show that the geoid variations caused by the 2004 December (Mw = 9.2) and 2005 March (Mw = 8.7) Sumatra earthquakes can be detected. At GRACE resolution, the 2004 December earthquake produced a strong coseismic decrease of the gravity field in the Andaman Sea, followed by relaxation in the area affected by both the Andaman 2004 and the Nias 2005 earthquakes. We find two characteristic timescales for the relaxation, with a fast variation occurring in the vicinity of the Central Andaman ridge. We discuss our coseismic observations in terms of density changes of crustal and upper-mantle rocks, and of the vertical displacements in the Andaman Sea. We interpret the post-seismic signal in terms of the viscoelastic response of the Earth's mantle. The transient component of the relaxation may indicate the presence of hot, viscous material beneath the active Central Andaman Basin. ?? 2007 The Authors Journal compilation ?? 2007 RAS.

The delineation and interpretation of the earth's gravity field. Annual progress report, 1 June 1988-31 May 1989

International Nuclear Information System (INIS)

Marsh, B.D.

1989-05-01

In an attempt to understand the mechanical interaction of a growing lithosphere containing fracture zones with small and large scale mantle convection, which gives rise to geoid anomalies in oceanic regions, a series of fluid dynamical experiments is in progress to investigate: (1) the influence of lithosphere structure, fluid depth and viscosity field on the onset, scale, and evolution of sublithospheric convection; (2) the role of this convection in determining the rate of growth of lithosphere, especially in light of the flattening of the lithosphere bathymetry and heat flow at late times; and (3) combining the results of both numerical and laboratory experiments to decide the dominate factors in producing geoid anomalies in oceanic regions through the thermo-mechanical interaction of the lithosphere and subjacent mantle. The clear existence of small scale convection associated with a downward propagating solidification front (i.e., the lithosphere) and a larger scale flow associated with a discontinuous upward heat flux (i.e., a fracture zone) has been shown. The flows exist simultaneously and each may have a significant role in deciding the thermal evolution of the lithosphere and in understanding the relation of shallow mantle convection to deep mantle convection. This overall process is reflected in the geoid, gravity, and topographic anomalies in the north-central Pacific. These highly correlated fields of intermediate wavelength (approx. 200 to 2000 km) show isostatic compensation by a thin lithosphere for shorter (less than or equal to approx. 500 km), but not the longer, wavelengths. The ultimate, dynamic origin of this class of anomalies is being investigated

Geodetic methods to determine the relativistic redshift at the level of 10^{-18} in the context of international timescales: a review and practical results

Science.gov (United States)

Denker, Heiner; Timmen, Ludger; Voigt, Christian; Weyers, Stefan; Peik, Ekkehard; Margolis, Helen S.; Delva, Pacôme; Wolf, Peter; Petit, Gérard

2017-12-01

The frequency stability and uncertainty of the latest generation of optical atomic clocks is now approaching the one part in 10^{18} level. Comparisons between earthbound clocks at rest must account for the relativistic redshift of the clock frequencies, which is proportional to the corresponding gravity (gravitational plus centrifugal) potential difference. For contributions to international timescales, the relativistic redshift correction must be computed with respect to a conventional zero potential value in order to be consistent with the definition of Terrestrial Time. To benefit fully from the uncertainty of the optical clocks, the gravity potential must be determined with an accuracy of about 0.1 m2 s^{-2} , equivalent to about 0.01 m in height. This contribution focuses on the static part of the gravity field, assuming that temporal variations are accounted for separately by appropriate reductions. Two geodetic approaches are investigated for the derivation of gravity potential values: geometric levelling and the Global Navigation Satellite Systems (GNSS)/geoid approach. Geometric levelling gives potential differences with millimetre uncertainty over shorter distances (several kilometres), but is susceptible to systematic errors at the decimetre level over large distances. The GNSS/geoid approach gives absolute gravity potential values, but with an uncertainty corresponding to about 2 cm in height. For large distances, the GNSS/geoid approach should therefore be better than geometric levelling. This is demonstrated by the results from practical investigations related to three clock sites in Germany and one in France. The estimated uncertainty for the relativistic redshift correction at each site is about 2 × 10^{-18}.

Roadmap to a mutually consistent set of offshore vertical reference frames

NARCIS (Netherlands)

Slobbe, D.C.

2013-01-01

This thesis presents a combined approach for the realization of the (quasi-)geoid as a height reference surface and the vertical reference surface at sea (chart datum). This approach, specifically designed for shallow seas and coastal waters, provides the relation between the two vertical reference

Light Obscuration Particle Counter Fuel Contamination Limits

Science.gov (United States)

2015-10-08

two methods for measuring particulate contamination by gravimetric analysis: ASTM D2276 - Standard Test Method for Particulate Contaminant in Aviation...problems with the gravimetric methods is the poor repeatability and reproducibility of the methods , ASTM D2276 has a repeatability of 0.25 mg/L and...collected failing either the particle count or the gravimetric limit, 314 of which failed both methods . 245 false negatives were recorded where the