WorldWideScience

Sample records for wind erosion prediction

  1. A history of wind erosion prediction models in the United States Department of Agriculture: The Wind Erosion Prediction System (WEPS)

    Science.gov (United States)

    Development of the Wind Erosion Prediction System (WEPS) was officially inaugurated in 1985 by United States Department of Agriculture-Agricultural Research Service (USDA-ARS) scientists in response to customer requests, particularly those coming from the USDA Soil Conservation Service (SCS), for im...

  2. Building Chinese wind data for Wind Erosion Prediction System using surrogate US data

    Science.gov (United States)

    Wind erosion is a global problem, especially in arid and semiarid regions of the world, which leads to land degradation and atmosphere pollution. The process-based Wind Erosion Prediction System (WEPS), developed by the USDA, is capable of simulating the windblown soil loss with changing weather and...

  3. A history of wind erosion prediction models in the United States Department of Agriculture prior to the Wind Erosion Prediction System

    Science.gov (United States)

    Tatarko, John; Sporcic, Michael A.; Skidmore, Edward L.

    2013-09-01

    The Great Plains experienced an influx of settlers in the late 1850s-1900. Periodic drought was hard on both settlers and the soil and caused severe wind erosion. The period known as the Dirty Thirties, 1931-1939, produced many severe windstorms, and the resulting dusty sky over Washington, DC helped Hugh Hammond Bennett gain political support for the Soil Conservation Act of 1937 that started the USDA Soil Conservation Service (SCS). Austin W. Zingg and William S. Chepil began wind erosion studies at a USDA laboratory at Kansas State University in 1947. Neil P. Woodruff and Francis H. Siddoway published the first widely used model for wind erosion in 1965, called the Wind Erosion Equation (WEQ). The WEQ was solved using a series of charts and lookup tables. Subsequent improvements to WEQ included monthly magnitudes of the total wind, a computer version of WEQ programmed in FORTRAN, small-grain equivalents for range grasses, tillage systems, effects of residue management, crop row direction, cloddiness, monthly climate factors, and the weather. The SCS and the Natural Resources Conservation Service (NRCS) produced several computer versions of WEQ with the goal of standardizing and simplifying it for field personnel including a standalone version of WEQ was developed in the late 1990s using Microsoft Excel. Although WEQ was a great advancement to the science of prediction and control of wind erosion on cropland, it had many limitations that prevented its use on many lands throughout the United States and the world. In response to these limitations, the USDA developed a process-based model know as the Wind Erosion Prediction System (WEPS). The USDA Agricultural Research Service has taken the lead in developing science and technology for wind erosion prediction.

  4. Wind erosion in semiarid landscapes: Predictive models and remote sensing methods for the influence of vegetation

    Science.gov (United States)

    Musick, H. Brad

    1993-01-01

    The objectives of this research are: to develop and test predictive relations for the quantitative influence of vegetation canopy structure on wind erosion of semiarid rangeland soils, and to develop remote sensing methods for measuring the canopy structural parameters that determine sheltering against wind erosion. The influence of canopy structure on wind erosion will be investigated by means of wind-tunnel and field experiments using structural variables identified by the wind-tunnel and field experiments using model roughness elements to simulate plant canopies. The canopy structural variables identified by the wind-tunnel and field experiments as important in determining vegetative sheltering against wind erosion will then be measured at a number of naturally vegetated field sites and compared with estimates of these variables derived from analysis of remotely sensed data.

  5. 75 FR 75961 - Notice of Implementation of the Wind Erosion Prediction System for Soil Erodibility System...

    Science.gov (United States)

    2010-12-07

    ... implementation of the WEPS system does not affect the Highly Erodible Map Unit List contained in the NRCS Field Office Technical Guide as of January 1, 1990. This 1990 list will continue to be used for all erodibility... plant damage, and predict PM-10 emissions when wind speeds exceed the erosion threshold. The WEPS model...

  6. A history of wind erosion prediction models in the United States Department of Agriculture Prior to the Wind Erosion Prediction System

    Science.gov (United States)

    The Great Plains experienced an influx of settlers in the late 1850s to 1900. Periodic drought was hard on both settlers and the soil and caused severe wind erosion. The period known as the Dirty Thirties, 1931 to 1939, produced many severe windstorms, and the resulting dusty sky over Washington, D....

  7. Wind erosion modelling in a Sahelian environment

    NARCIS (Netherlands)

    Faye-Visser, S.M.; Sterk, G.; Karssenberg, D.

    2005-01-01

    In the Sahel field observations of wind-blown mass transport often show considerable spatial variation related to the spatial variation of the wind erosion controlling parameters, e.g. soil crust and vegetation cover. A model, used to predict spatial variation in wind erosion and deposition is a

  8. Wind erosion processes and control

    Science.gov (United States)

    Wind erosion continues to threaten the sustainability of our nations' soil, air, and water resources. To effectively apply conservation systems to prevent wind driven soil loss, an understanding of the fundamental processes of wind erosion is necessary so that land managers can better recognize the ...

  9. Wind erosion of soils burned by wildfire

    Science.gov (United States)

    N. S. Wagenbrenner; M. J. Germino; B. K. Lamb; R. B. Foltz; P. R. Robichaud

    2011-01-01

    Wind erosion and aeolian transport processes are largely unstudied in the post-wildfire environment, but recent studies have shown that wind erosion can play a major role in burned landscapes. A wind erosion monitoring system was installed immediately following a wildfire in southeastern Idaho, USA to measure wind erosion from the burned area (Figure 1). This paper...

  10. Development of an Integrated Water and Wind Erosion Model

    Science.gov (United States)

    Flanagan, D. C.; Ascough, J. C.; Wagner, L. E.; Geter, W. F.

    2006-12-01

    Prediction technologies for soil erosion by the forces of wind or water have largely been developed independently from one another, especially within the United States. Much of this has been due to the initial creation of equations and models which were empirical in nature (i.e., Universal Soil Loss Equation, Wind Erosion Equation) and based upon separate water erosion or wind erosion plot and field measurements. Additionally, institutional organizations in place typically divided research efforts and funding to unique wind or water erosion research and modeling projects. However, during the past 20 years computer technologies and erosion modeling have progressed to the point where it is now possible to merge physical process-based computer simulation models into an integrated water and wind erosion prediction system. In a physically- based model, many of the processes which must be simulated for wind and water erosion computations are the same, e.g., climate, water balance, runoff, plant growth, etc. Model components which specifically deal with the wind or water detachment, transport and deposition processes are those that must differ, as well as any necessary parameterization of input variables (e.g., adjusted soil erodibilities, critical shear stresses, etc.) for those components. This presentation describes current efforts towards development of a combined wind and water erosion model, based in part upon technologies present in the Water Erosion Prediction Project (WEPP) and the Wind Erosion Prediction System (WEPS) models. Initial efforts during the past two years have resulted in modular modeling components that allow for prediction of infiltration, surface runoff, and water erosion at a hillslope scale within an Object Modeling System. Additional components currently in development include wind detachment at a single field point, continuous water balance, and unified plant growth. Challenges in this project are many, and include adequate field

  11. Integrated spatial assessment of wind erosion risk in Hungary

    Directory of Open Access Journals (Sweden)

    L. Pásztor

    2016-11-01

    Full Text Available Wind erosion susceptibility of Hungarian soils was mapped on the national level integrating three factors of the complex phenomenon of deflation (physical soil features, wind characteristics, and land use and land cover. Results of wind tunnel experiments on erodibility of representative soil samples were used for the parametrization of a countrywide map of soil texture compiled for the upper 5 cm layer of soil, which resulted in a map representing threshold wind velocity exceedance. Average wind velocity was spatially estimated with 0.5′ resolution using the Meteorological Interpolation based on Surface Homogenised Data Basis (MISH method elaborated for the spatial interpolation of surface meteorological elements. The probability of threshold wind velocity exceedance was determined based on values predicted by the soil texture map at the grid locations. Ratio values were further interpolated to a finer 1 ha resolution using sand and silt content of the uppermost (0–5 cm layer of soil as spatial co-variables. Land cover was also taken into account, excluding areas that are not relevant to wind erosion (forests, water bodies, settlements, etc., to spatially assess the risk of wind erosion. According to the resulting map of wind erosion susceptibility, about 10 % of the total area of Hungary can be identified as susceptible to wind erosion. The map gives more detailed insight into the spatial distribution of wind-affected areas in Hungary compared to previous studies.

  12. On the prediction of threshold friction velocity of wind erosion using soil reflectance spectroscopy

    Science.gov (United States)

    Li, Junran; Flagg, Cody B.; Okin, Gregory S.; Painter, Thomas H.; Dintwe, Kebonye; Belnap, Jayne

    2015-01-01

    Current approaches to estimate threshold friction velocity (TFV) of soil particle movement, including both experimental and empirical methods, suffer from various disadvantages, and they are particularly not effective to estimate TFVs at regional to global scales. Reflectance spectroscopy has been widely used to obtain TFV-related soil properties (e.g., moisture, texture, crust, etc.), however, no studies have attempted to directly relate soil TFV to their spectral reflectance. The objective of this study was to investigate the relationship between soil TFV and soil reflectance in the visible and near infrared (VIS–NIR, 350–2500 nm) spectral region, and to identify the best range of wavelengths or combinations of wavelengths to predict TFV. Threshold friction velocity of 31 soils, along with their reflectance spectra and texture were measured in the Mojave Desert, California and Moab, Utah. A correlation analysis between TFV and soil reflectance identified a number of isolated, narrow spectral domains that largely fell into two spectral regions, the VIS area (400–700 nm) and the short-wavelength infrared (SWIR) area (1100–2500 nm). A partial least squares regression analysis (PLSR) confirmed the significant bands that were identified by correlation analysis. The PLSR further identified the strong relationship between the first-difference transformation and TFV at several narrow regions around 1400, 1900, and 2200 nm. The use of PLSR allowed us to identify a total of 17 key wavelengths in the investigated spectrum range, which may be used as the optimal spectral settings for estimating TFV in the laboratory and field, or mapping of TFV using airborne/satellite sensors.

  13. Mechanics of interrill erosion with wind-driven rain

    Science.gov (United States)

    The vector physics of wind-driven rain (WDR) differs from that of wind-free rain, and the interrill soil detachment equations in the Water Erosion Prediction Project (WEPP) model were not originally developed to deal with this phenomenon. This article provides an evaluation of the performance of the...

  14. Mechanics of Interrill Erosion with Wind-Driven Rain (WDR)

    Science.gov (United States)

    This article provides an evaluation analysis for the performance of the interrill component of the Water Erosion Prediction Project (WEPP) model for Wind-Driven Rain (WDR) events. The interrill delivery rates (Di) were collected in the wind tunnel rainfall simulator facility of the International Cen...

  15. Determining Wind Erosion in the Great Plains

    OpenAIRE

    Elwin G. Smith; Burton C. English

    1982-01-01

    Wind erosion is defined as the movement of soil particles resulting from strong turbulent winds. The movement of soil particles can be categorized as suspension, saltation, or surface creep. Fine soil particles can be suspended in the atmosphere and carried for great distances. Particles too large to be suspended move in a jumping action along the soil surface, known as saltation. Heavier particles have a rolling movement along the surface and this type of erosion is surface creep.

  16. Using albedo to reform wind erosion modelling, mapping and monitoring

    Science.gov (United States)

    Chappell, Adrian; Webb, Nicholas P.

    2016-12-01

    Wind erosion and dust emission models are used to assess the impacts of dust on radiative forcing in the atmosphere, cloud formation, nutrient fertilisation and human health. The models are underpinned by a two-dimensional geometric property (lateral cover; L) used to characterise the three-dimensional aerodynamic roughness (sheltered area or wakes) of the Earth's surface and calibrate the momentum it extracts from the wind. We reveal a fundamental weakness in L and demonstrate that values are an order of magnitude too small and significant aerodynamic interactions between roughness elements and their sheltered areas have been omitted, particularly under sparse surface roughness. We describe a solution which develops published work to establish a relation between sheltered area and the proportion of shadow over a given area; the inverse of direct beam directional hemispherical reflectance (black sky albedo; BSA). We show direct relations between shadow and wind tunnel measurements and thereby provide direct calibrations of key aerodynamic properties. Estimation of the aerodynamic parameters from albedo enables wind erosion assessments over areas, across platforms from the field to airborne and readily available satellite data. Our new approach demonstrated redundancy in existing wind erosion models and thereby reduced model complexity and improved fidelity. We found that the use of albedo enabled an adequate description of aerodynamic sheltering to characterise fluid dynamics and predict sediment transport without the use of a drag partition scheme (Rt) or threshold friction velocity (u∗t). We applied the calibrations to produce global maps of aerodynamic properties which showed very similar spatial patterns to each other and confirmed the redundancy in the traditional parameters of wind erosion modelling. We evaluated temporal patterns of predicted horizontal mass flux at locations across Australia which revealed variation between land cover types that would not

  17. On the geoethical implications of wind erosion

    Science.gov (United States)

    Károly, Tatárvári

    2016-04-01

    Human activities exerts an ever growing impact on our environment, and this is undeniably the responsibility of mankind. In spite of this fact there is almost no process in our environment that can be described exactly with complete exactness, and the working of which is known in full extent. Wind erosion is such a process. Although water erosion is mentioned ever more often in scientific circles as a from of erosion, its effect is restrained to a certain region, although it may cause perceptibly damage of a greater extent in short time. Wind erosion, apart from the fact that it may have global impact, may play an important role in the warming of our climate according to recent studies. First of all, wind erosion may cause damage far from its origin in human health, nutrition, or in the environment in general. Today several surveys have proved, that erosion caused by wind significantly contributes to the air pollution of cities, the fine dust carried as drift by the wind may cause severe environmental damage in accumulation zones. Microbes, toxic material may attach themselves to the dust carried this way and carried on and by the wings of the wind they may cause health issues in humans animals and plants as well. In spite of these facts there are almost no measures against wind erosion employed in arable land, although our ever doughtier climate and changes would make these necessary. Reduction of organic matter content presents a great problem in a large part of cultivated land, so the risk of the production of high quality food raises questions of more and more ethical nature. Who is responsible? The fact, that the chemicals used in a growing extent by agriculture may reach many people causing considerable damage to the environment also raises serious ethical questions. More and more periods with extreme weather conditions are experienced in Hungary and Europe as the effect of climate change. Drought periods are longer and more frequent as the intensity of

  18. Modelling of environmental and climatic problems: Wind and water erosion

    International Nuclear Information System (INIS)

    Aslan, Z.

    2004-01-01

    Magnitude of wind and water erosion mainly depend on wind velocity, rainfall rate, slope and soil characteristics. The main purpose of this lecture is to define the role of small, meso and large scale phenomena (local and synoptic fluctuations) on water and wind erosion. These lecture notes present some results on wind speed simulation and seasonal fluctuations of water deficit for the selected station in different erosion risque and transition regions of Turkey. (author)

  19. Wind and water erosion control on semiarid lands

    International Nuclear Information System (INIS)

    Siddoway, F.H.

    1980-01-01

    Commercial crop production on semiarid lands is difficult because insufficient water is often present to manage the system effectively. Erosion control presents the major management problem. The factors contributing to wind erosion and their interaction have been quantified into a wind erosion equation. The control of wind erosion through agronomic alteration of the various factors is discussed. The quantification and control of water erosion is also discussed with respect to the Universal Soil Loss Equation. Radioisotopes tracers have been used in conjunction with these erosion equations to measure soil losses. (author)

  20. Soil deflation analyses from wind erosion events

    Directory of Open Access Journals (Sweden)

    Lenka Lackóová

    2015-09-01

    Full Text Available There are various methods to assess soil erodibility for wind erosion. This paper focuses on aggregate analysis by a laser particle sizer ANALYSETTE 22 (FRITSCH GmbH, made to determine the size distribution of soil particles detached by wind (deflated particles. Ten soil samples, trapped along the same length of the erosion surface (150–155 m but at different wind speeds, were analysed. The soil was sampled from a flat, smooth area without vegetation cover or soil crust, not affected by the impact of windbreaks or other barriers, from a depth of maximum 2.5 cm. Prior to analysis the samples were prepared according to the relevant specifications. An experiment was also conducted using a device that enables characterisation of the vertical movement of the deflated material. The trapped samples showed no differences in particle size and the proportions of size fractions at different hourly average wind speeds. It was observed that most of particles travelling in saltation mode (size 50–500 μm – 58–70% – moved vertically up to 26 cm above the soil surface. At greater heights, particles moving in suspension mode (floating in the air; size < 100 μm accounted for up to 90% of the samples. This result suggests that the boundary between the two modes of the vertical movement of deflated soil particles lies at about 25 cm above the soil surface.

  1. AERO: A Decision Support Tool for Wind Erosion Assessment in Rangelands and Croplands

    Science.gov (United States)

    Galloza, M.; Webb, N.; Herrick, J.

    2015-12-01

    Wind erosion is a key driver of global land degradation, with on- and off-site impacts on agricultural production, air quality, ecosystem services and climate. Measuring rates of wind erosion and dust emission across land use and land cover types is important for quantifying the impacts and identifying and testing practical management options. This process can be assisted by the application of predictive models, which can be a powerful tool for land management agencies. The Aeolian EROsion (AERO) model, a wind erosion and dust emission model interface provides access by non-expert land managers to a sophisticated wind erosion decision-support tool. AERO incorporates land surface processes and sediment transport equations from existing wind erosion models and was designed for application with available national long-term monitoring datasets (e.g. USDI BLM Assessment, Inventory and Monitoring, USDA NRCS Natural Resources Inventory) and monitoring protocols. Ongoing AERO model calibration and validation are supported by geographically diverse data on wind erosion rates and land surface conditions collected by the new National Wind Erosion Research Network. Here we present the new AERO interface, describe parameterization of the underpinning wind erosion model, and provide a summary of the model applications across agricultural lands and rangelands in the United States.

  2. Incorporating the Wind Erosion Prediction System (WEPS) Into a Regional Air Quality Modeling System for the Pacific Northwest

    Science.gov (United States)

    In the Pacific Northwest, wind storms intermittently cause massive dust events that reduce visibility along roadways and jeopardize health as a result of extremely high concentrations of PM10 (particulate matter less than or equal to 10µm in diameter). An early warning dust forecast system is needed...

  3. [Research progress on wind erosion control with polyacrylamide (PAM).

    Science.gov (United States)

    Li, Yuan Yuan; Wang, Zhan Li

    2016-03-01

    Soil wind erosion is one of the main reasons for soil degradation in the northwest region of China. Polyacrylamide (PAM), as an efficient soil amendment, has gained extensive attention in recent years since it is effective in improving the structure of surface soil due to its special physical and chemical properties. This paper introduced the physical and chemical properties of PAM, reviewed the effects of PAM on soil wind erosion amount and threshold wind velocity, as well as the effect differences of PAM in soil wind erosion control under conditions of various methods and doses. Its effect was proved by comparing with other materials in detail. Furthermore, we analyzed the mecha-nism of wind erosion control with PAM according to its influence on soil physical characteristics. Comprehensive analysis showed that, although some problems existed in wind erosion control with (PAM), PAM as a sand fixation agent, can not only enhance the capacity of the soil resis-tance to wind erosion, but also improve soil physical properties to form better soil conditions. Besides, we proposed that combination of PAM and plant growth would increase the survival rate of plants greatly, control soil wind erosion in wind-erosive areas, and improve the quality of the ecological environment construction. Thus, PAM has practically important significance and wide application prospect in controlling soil wind erosion.

  4. Wind power prediction models

    Science.gov (United States)

    Levy, R.; Mcginness, H.

    1976-01-01

    Investigations were performed to predict the power available from the wind at the Goldstone, California, antenna site complex. The background for power prediction was derived from a statistical evaluation of available wind speed data records at this location and at nearby locations similarly situated within the Mojave desert. In addition to a model for power prediction over relatively long periods of time, an interim simulation model that produces sample wind speeds is described. The interim model furnishes uncorrelated sample speeds at hourly intervals that reproduce the statistical wind distribution at Goldstone. A stochastic simulation model to provide speed samples representative of both the statistical speed distributions and correlations is also discussed.

  5. Wind erosion control of soils using polymeric materials

    Directory of Open Access Journals (Sweden)

    Mohammad Movahedan

    2012-07-01

    Full Text Available Wind erosion of soils is one of the most important problems in environment and agriculture which could affects several fields. Agricultural lands, water reservoires, irrigation canals, drains and etc. may be affected by wind erosion and suspended particles. As a result wind erosion control needs attention in arid and semi-arid regions. In recent years, some polymeric materials have been used for improvement of structural stability, increasing aggregate stability and soil stabilization, though kind of polymer, quantity of polymer, field efficiency and durability and environmental impacts are some important parameters which should be taken into consideration. In this study, a Polyvinil Acetate-based polymer was used to treat different soils. Then polymer-added soil samples were investigated experimentally in a wind tunnel to verify the effecte of polymer on wind erosion control of the soils and the results were compared with water treated soil samples. The results of wind tunnel experiments with a maximum 26 m/s wind velocity showed that there was a significat difference between the erosion of polymer treated and water treated soil samples. Application of 25g/m2 polymer to Aeolian sands reduced the erosion of Aeolian sands samples to zero related to water treated samples. For silty and calyey soils treated by polymer, the wind erosion reduced minimum 90% in relation to water treated samples.

  6. Wind erosion potential after land application of biosolids

    Science.gov (United States)

    PI, H.; Sharratt, B. S.; Schillinger, W. F.; Bary, A.; Cogger, C.

    2017-12-01

    The world population is currently 7.6 billion and, along with continued population growth, comes the challenge of disposing of wastewater and sewage sludge (biosolids). Applying biosolids to agricultural land to replace synthetic fertilizers represents a relatively safe method to recycle or sustainably use biosolids. While land application of biosolids is recognized as a sustainable management practice for enhancing soil health, no studies have determined the effects of biosolids on soil wind erosion. Wind erosion potential of a silt loam was assessed using a portable wind tunnel after applying synthetic and biosolid fertilizer to conventional and conservation tillage practices during the summer fallow phase of a winter wheat-summer fallow rotation in 2015 and 2016 in east-central Washington. Little difference in soil loss was observed between biosolid and synthetic fertilizer treatments, but this result appeared to be dependent on susceptibility of the soil to erosion. Regression analysis between soil loss from fertilizer or tillage treatments indicated that soil loss was lower from biosolid versus synthetic fertilizer and conservation versus conventional tillage at high erosion rates. This suggests that biosolids may reduce wind erosion under highly erodible conditions. Meanwhile, heavy metal concentrations in the windblown sediment were similar for the biosolid and synthetic fertilizer treatments whereas metal loss in windblown sediment was 10% lower from biosolid than synthetic fertilizer. Our results indicate that land application of biosolids did not accelerate the loss of metals or nutrients from soils during high winds. KeywordsLand application of biosolids; wind erosion; wind tunnel; sustainable agriculture

  7. Wind tunnel experiments on the effects of tillage ridge features on wind erosion horizontal fluxes

    Directory of Open Access Journals (Sweden)

    M. Kardous

    2005-11-01

    Full Text Available In addition to the well-known soil factors which control wind erosion on flat, unridged surfaces, two specific processes affect the susceptibility of tillage ridged surfaces to wind erosion: ridge-induced roughness and ridge- trapping efficiency. In order to parameterize horizontal soil fluxes produced by wind over tillage ridges, eight-ridge configurations composed of sandy soil and exhibiting ridge heights to ridge spacing (RH/RS ratios ranging from 0.18 to 0.38 were experimented in a wind tunnel. These experiments are used to develop a parameterization of the horizontal fluxes over tillage ridged surfaces based only on the geometric characteristics of the ridges. Indeed, the key parameters controlling the horizontal flux, namely the friction velocity, threshold friction velocity and the adjustment coefficient, are derived through specific expressions, from ridge heights (RH and ridge spacing (RS. This parameterization was evaluated by comparing the results of the simulations to an additional experimental data set and to the data set obtained by Hagen and Armbrust (1992. In both cases, predicted and measured values are found to be in a satisfying agreement. This parameterization was used to evaluate the efficiency of ridges in reducing wind erosion. The results show that ridged surfaces, when compared to a loose, unridged soil surface, lead to an important reduction in the horizontal fluxes (exceeding 60%. Moreover, the effect of ridges in trapping particles contributes for more than 90% in the flux reduction while the ridge roughness effect is weak and decreases when the wind velocity increases.

  8. Wind tunnel experiments on the effects of tillage ridge features on wind erosion horizontal fluxes

    Directory of Open Access Journals (Sweden)

    M. Kardous

    2005-11-01

    Full Text Available In addition to the well-known soil factors which control wind erosion on flat, unridged surfaces, two specific processes affect the susceptibility of tillage ridged surfaces to wind erosion: ridge-induced roughness and ridge- trapping efficiency.

    In order to parameterize horizontal soil fluxes produced by wind over tillage ridges, eight-ridge configurations composed of sandy soil and exhibiting ridge heights to ridge spacing (RH/RS ratios ranging from 0.18 to 0.38 were experimented in a wind tunnel. These experiments are used to develop a parameterization of the horizontal fluxes over tillage ridged surfaces based only on the geometric characteristics of the ridges. Indeed, the key parameters controlling the horizontal flux, namely the friction velocity, threshold friction velocity and the adjustment coefficient, are derived through specific expressions, from ridge heights (RH and ridge spacing (RS. This parameterization was evaluated by comparing the results of the simulations to an additional experimental data set and to the data set obtained by Hagen and Armbrust (1992. In both cases, predicted and measured values are found to be in a satisfying agreement.

    This parameterization was used to evaluate the efficiency of ridges in reducing wind erosion. The results show that ridged surfaces, when compared to a loose, unridged soil surface, lead to an important reduction in the horizontal fluxes (exceeding 60%. Moreover, the effect of ridges in trapping particles contributes for more than 90% in the flux reduction while the ridge roughness effect is weak and decreases when the wind velocity increases.

  9. Estimation of wind erosion from construction of a railway in arid Northwest China

    Directory of Open Access Journals (Sweden)

    Benli Liu

    2017-06-01

    Full Text Available A state-of-the-art wind erosion simulation model, the Wind Erosion Prediction System and the United States Environmental Protection Agency's AP 42 emission factors formula, were combined together to evaluate wind-blown dust emissions from various construction units from a railway construction project in the dry Gobi land in Northwest China. The influence of the climatic factors: temperature, precipitation, wind speed and direction, soil condition, protective measures, and construction disturbance were taken into account. Driven by daily and sub-daily climate data and using specific detailed management files, the process-based WEPS model was able to express the beginning, active, and ending phases of construction, as well as the degree of disturbance for the entire scope of a construction project. The Lanzhou-Xinjiang High-speed Railway was selected as a representative study because of the diversities of different climates, soil, and working schedule conditions that could be analyzed. Wind erosion from different working units included the building of roadbeds, bridges, plants, temporary houses, earth spoil and barrow pit areas, and vehicle transportation were calculated. The total wind erosion emissions, 7406 t, for the first construction area of section LXS-15 with a 14.877 km length was obtained for quantitative analysis. The method used is applicable for evaluating wind erosion from other complex surface disturbance projects.

  10. Accelerated rain erosion of wind turbine blade coatings

    DEFF Research Database (Denmark)

    Zhang, Shizhong

    . There are four chapters in the thesis. In chapter 1, a literature survey provides background information to the field. Topics discussed are the global wind energy development, possible wind turbine constructions, blade structures and materials, blade coatings, and liquid erosion mechanisms. In chapter 2......During operation, the fast-moving blades of wind turbines are exposed to continuous impacts with rain droplets, hail, insects, or solid particles. This can lead to erosion of the blades, whereby the electrical efficiency is compromised and expensive repairs may be required. One possible solution...

  11. Wind driven erosion and the effects of particulate electrification

    Science.gov (United States)

    Merrison, J. P.; Bak, E.; Finster, K.; Gunnlaugsson, H. P.; Holstein-Rathlou, C.; Knak Jensen, S.; Nørnberg, P.; Rasmussen, K. R.

    2012-09-01

    Several related aspects of Aeolian activity are presently being studied in the laboratory, the most recent advances in this field will be presented. These include simulating wind driven erosion in the laboratory, quantifying erosion rates and the study of mineral change due to mechanical activation. Also advances in our understanding of the electrification of sand/dust particles is being made and how this phenomenon affects their behavior.

  12. Climate change and wind erosion by dust storms

    International Nuclear Information System (INIS)

    Wheaton, E.E.; Wittrock, V.

    1991-01-01

    Dust storms and their associated wind erosion are thought to be almost synonymous with drought. Dust storms have varying impacts including sandblasting and burying crops, wind erosion of soil, health effects and traffic accidents. A comparison of drought periods for southern Saskatchewan with dust storm frequencies for the period 1977-1988 revealed that the worst drought conditions coincided with the greatest April dust storm frequencies, with 1981 having the worst drought, and secondary spring droughts occurring in 1977, 1988, 1980 and 1982, and spring dust storm peaks occurring, in order of magnitude, in 1981, 1977, 1987, and 1982. An increase in atmospheric dust particles may lead to enhanced atmospheric subsidence and associated drought, and could be a positive feedback for drought intensity. Wind erosion potential may rise with rising temperature due to decreased vegetation cover, but the effect might be offset by rising precipitation

  13. Determination of wind erosion intensity on heavy clay soils

    Directory of Open Access Journals (Sweden)

    Jana Kozlovsky Dufková

    2010-01-01

    Full Text Available Wind erosion, common problem of light-textured soils, was determined on heavy clay soils in the foothills of Bílé Karpaty Mountains, Czech Republic. Soil erodibility by wind was determined from the Map of potential erodibility of soil by wind and from the calculation of potential and real soil loss by wind. All the determinations show underestimation of soil erodibility by wind on heavy clay soils, because methods that are used for this are based above all on the assessment of clay particles content and the presumption the more clay particles soil contains, the less vulnerable to wind erosion is. The potential erodibility of soil by wind is 0,09 t . ha−1 per year. The determined value does not exceed the tolerable soil loss limit 10 t . ha−1 per year for deep soils. The real average erodibility of soil by wind has the highest value 1,47 g . m−2 on November 30th, 2008. Other soil losses that do not exceed the tolerable soil loss limit 1,4 g . m−2, were determined on March 18th and 28th, 2008. Big difficulties come with the assessment of the erodibility of heavy clay soils in the areas, where soil erosion ve­ri­fia­bly exists, but it is not assessable by objective calculating methods. Evident necessity of new know­ledge concerning the determination of wind erosion intensity follows from the results.

  14. Wind tunnel experimental study on the effect of PAM on soil wind erosion control.

    Science.gov (United States)

    He, Ji-Jun; Cai, Qiang-Guo; Tang, Ze-Jun

    2008-10-01

    In recent years, high-molecular-weight anionic polyacrylamide (PAM) have been widely tested on a variety of soils, primarily in water erosion control. However, little information is available regarding the effectiveness of PAM on preventing soil loss from wind erosion. The research adopted room wind tunnel experiment, two kinds of soils were used which were from the agro-pastoral area of Inner Mongolia, the northwest of China, the clay content of soils were 22.0 and 13.7%, respectively. For these tests, all the treatments were performed under the condition of wind velocity of 14 m s(-1) and a blown angle of 8.75%, according to the actual situation of experimented area. The study results indicated that using PAM on the soil surface could enhance the capability of avoiding the wind erosion, at the same time, the effect of controlling wind soil erosion with 4 g m(-2) PAM was better than 2 g m(-2) PAM's. Economically, the 2 g m(-2) PAM used in soil surface can control wind erosion effectively in this region. The prophase PAM accumulated in soil could not improve the capability of avoiding the wind erosion, owing to the degradation of PAM in the soil and the continual tillage year after year. The texture of soil is a main factor influencing the capability of soil avoiding wind erosion. Soil with higher clay content has the higher capability of preventing soil from wind erosion than one with the opposite one under the together action of PAM and water.

  15. An index guiding temporal planting policies for wind erosion reduction

    NARCIS (Netherlands)

    Zhao, C.X.; Zheng, D.W.; Stigter, C.J.; He, W.Q.; Tuo, D.B.; Zhao, P.

    2006-01-01

    Vegetation cover has spatial as well as temporal characteristics, but the latter are often neglected. Temporal cover characteristics were explored to recommend planting policies for returning arable land into land better protected from serious wind erosion during late autumn, winter, and

  16. Dryland Degradation by wind erosion and its control

    NARCIS (Netherlands)

    Sterk, G.; Riksen, M.; Goossens, D.

    2001-01-01

    Global population growth, is expected to impose an increasing pressure on agricultural production in the world's drylands, which cover approximately 41␘f the continental area. The land resources in drylands are severely threatened by soil degradation, with wind erosion being, one of the major

  17. Crater Mound Formation by Wind Erosion on Mars

    Science.gov (United States)

    Steele, L. J.; Kite, E. S.; Michaels, T. I.

    2018-01-01

    Most of Mars' ancient sedimentary rocks by volume are in wind-eroded sedimentary mounds within impact craters and canyons, but the connections between mound form and wind erosion are unclear. We perform mesoscale simulations of different crater and mound morphologies to understand the formation of sedimentary mounds. As crater depth increases, slope winds produce increased erosion near the base of the crater wall, forming mounds. Peak erosion rates occur when the crater depth is ˜2 km. Mound evolution depends on the size of the host crater. In smaller craters mounds preferentially erode at the top, becoming more squat, while in larger craters mounds become steeper sided. This agrees with observations where smaller craters tend to have proportionally shorter mounds and larger craters have mounds encircled by moats. If a large-scale sedimentary layer blankets a crater, then as the layer recedes across the crater it will erode more toward the edges of the crater, resulting in a crescent-shaped moat. When a 160 km diameter mound-hosting crater is subject to a prevailing wind, the surface wind stress is stronger on the leeward side than on the windward side. This results in the center of the mound appearing to "march upwind" over time and forming a "bat-wing" shape, as is observed for Mount Sharp in Gale crater.

  18. WIND EROSION INTENSITY DETERMINATION USING SOIL PARTICLE CATCHER DEVICES

    Directory of Open Access Journals (Sweden)

    Lenka Lackóová

    2013-12-01

    Full Text Available To analyze wind erosion events in the real terrain conditions, we proposed to construct a prototype of soil particle catcher devices to trap soil particles. With these devices we are able to measure the intensity of wind erosion at six different heights above the soil surface in one location or at three different heights in two places. It is possible to use them for six different places at the same time as well. We performed field measurements to determine the amount of soil particles transported by the wind between 26th – 31st March 2012. Each measuring took 60 minutes. After this time the soil particle catchers were emptied and further measurements carried out. At the beginning we selected two places for measurement (soil HPJ 16 and 37 at two heights, one above the other. Then we used two measuring systems 40 m apart at two sites (D2 and D4 and the soil captured at two heights (0, 1. The maximum weight of soil particles trapped in measuring system D2 at height (0 was 1242.7 g at a wind speed of 9.6 ms-1. At measurement height (1 the maximum weight was 72.7 g trapped at the same average hourly rate, but during different measurement events. The measuring system at D4 trapped the highest amount of soil at a wind speed of 8.9 ms-1 (1141.7 g at height (0 and at a speed of 9.3 ms-1 (22.3 g at height (1. During the measurements with the two basic measuring systems D4 and D2, we measured the wind erosion intensity together with soil particle catchers D1 and D3. D3 was placed between devices D4 and D2, D1 was 20 m ahead D2. Soil particle catchers were placed on the soil surface at height position (0. We measured increasing soil erosion downwind on four locations spaced at 20 m. The results show that with there is an increasing quantity of particles collected as the erosive surface length increases, due to the so-called snowball effect. We analyzed selected trapped soil samples in order to determine the size of the soil particles and their proportion

  19. Implications of climate change on wind erosion of agricultural lands in the Columbia plateau

    Directory of Open Access Journals (Sweden)

    B.S. Sharratt

    2015-12-01

    Full Text Available Climate change may impact soil health and productivity as a result of accelerated or decelerated rates of erosion. Previous studies suggest a greater risk of wind erosion on arid and semi-arid lands due to loss of biomass under a future warmer climate. There have been no studies conducted to assess the impact of climate change on wind erosion in the Columbia Plateau of the Pacific Northwest United States where wind erosion of agricultural lands can cause exceedance of national air quality standards. The Wind Erosion Prediction System (WEPS was used to assess wind erosion and PM10 (particulate matter ≤10 µm in aerodynamic diameter emissions under a future climate projected by downscaling 18 Global Climate Models (GCM for a conservative emissions pathway. Wind erosion simulations were conducted at Lacrosse and Lind, WA and Moro, OR on a winter wheat-summer fallow (WW-SF rotation and at Lind on an additional winter wheat-camelina-summer fallow (WW-Cam-SF rotation. Each rotation was subject to conservation or conventional tillage practices for a baseline (1970–1999 and mid-21st century climate (2035–2064. A significant increase in temperature and nominal increases in precipitation were projected by an ensemble of climate models for the Columbia Plateau by the mid-21st century. Soil and PM10 losses were 25–84% lower for a mid-21st century climate, due in part to greater biomass production associated with CO2 fertilization and warmer temperatures. The reduction in soil and PM10 loss is projected to be more apparent for conservation tillage practices in the future. Soil and PM10 losses were greater from a WW-Cam-SF rotation than WW-SF rotation when conservation tillage practices were employed during the fallow phase of the rotations. Despite accounting for differences in the length of each rotation, annual soil and PM10 losses remained higher for the WW-Cam-SF rotation than the WW-SF rotation. Soil and PM10 losses were more variable across

  20. Ice-Release and Erosion Resistant Materials for Wind Turbines

    Science.gov (United States)

    Zhang, Wei; Brinn, Cameron; Cook, Alex; Pascual-Marquez, Fernando

    2017-11-01

    Icing conditions may cause wind turbine generators to partially lose productivity or to be completely shut down to avoid structural damage. At present, commercially available technologies to mitigate this problem consist of expensive, energy hungry heating elements, which costs roughly 70,000 euro per medium size turbine. Conventional passive ice protection coating systems heavily rely on delicate surface structures and expensive materials to create water repellent superhydrophobic / low surface energy surfaces, which have been proven to be ineffective against ice accumulation. The lack of performance among conventional ice protection materials stems from a flaw in the approach to the problem: failure to recognize that water in its liquid form (WATER) and water in its solid form (ICE) are two different things. Something that works for WATER does not automatically work for ICE. Another reason is that many superhydrophobic materials are often reliant upon often fragile micro-structured surfaces to achieve their intended effects. This paper discusses a fundamentally different approach to the creation of a robust, low cost, durable, and multifunctional materials for ice release and erosion resistance. This National Science Foundation sponsored ice-release coating technology holds promise for protecting wind turbine blades and towers, thus potentially increasing reliability for power generation under icing conditions. Because of the vulnerability of wind turbine blades to ice buildup and erosion damages, wind farm facilities stand to reap considerable benefits.

  1. Numerical Modelling and Prediction of Erosion Induced by Hydrodynamic Cavitation

    Science.gov (United States)

    Peters, A.; Lantermann, U.; el Moctar, O.

    2015-12-01

    The present work aims to predict cavitation erosion using a numerical flow solver together with a new developed erosion model. The erosion model is based on the hypothesis that collapses of single cavitation bubbles near solid boundaries form high velocity microjets, which cause sonic impacts with high pressure amplitudes damaging the surface. The erosion model uses information from a numerical Euler-Euler flow simulation to predict erosion sensitive areas and assess the erosion aggressiveness of the flow. The obtained numerical results were compared to experimental results from tests of an axisymmetric nozzle.

  2. Soil erosion rates caused by wind and saltating sand stresses in a wind tunnel

    International Nuclear Information System (INIS)

    Ligotke, M.W.

    1993-02-01

    Wind erosion tests were performed in a wind tunnel in support of the development of long-term protective barriers to cap stabilized waste sites at the Hanford Site. Controlled wind and saltating sand erosive stresses were applied to physical models of barrier surface layers to simulate worst-case eolian erosive stresses. The goal of these tests was to provide information useful to the design and evaluation of the surface layer composition of an arid-region waste site barrier concept that incorporates a deep fine-soil reservoir. A surface layer composition is needed that will form an armor resistant to eolian erosion during periods of extreme dry climatic conditions, especially when such conditions result in the elimination or reduction of vegetation by water deprivation or wildfire. Because of the life span required of Hanford waste barriers, it is important that additional work follow these wind tunnel studies. A modeling effort is planned to aid the interpretation of test results with respect to the suitability of pea gravel to protect the finite-soil reservoir during long periods of climatic stress. It is additionally recommended that wind tunnel tests be continued and field data be obtained at prototype or actual barrier sites. Results wig contribute to barrier design efforts and provide confidence in the design of long-term waste site caps for and regions

  3. Particle transport patterns of short-distance soil erosion by wind-driven rain, rain and wind

    Science.gov (United States)

    Marzen, Miriam; Iserloh, Thomas; de Lima, João L. M. P.; Ries, Johannes B.

    2015-04-01

    Short distance erosion of soil surface material is one of the big question marks in soil erosion studies. The exact measurement of short-distance transported soil particles, prior to the occurrence of overland flow, is a challenge to soil erosion science due to the particular requirements of the experimental setup and test procedure. To approach a quantification of amount and distance of each type of transport, we applied an especially developed multiple-gutter system installed inside the Trier Portable Wind and Rainfall Simulator (PWRS). We measured the amount and travel distance of soil particles detached and transported by raindrops (splash), wind-driven rain (splash-saltation and splash-drift) and wind (saltation). The test setup included three different erosion agents (rain/ wind-driven rain/ wind), two substrates (sandy/ loamy), three surface structures (grain roughness/ rills lengthwise/ rills transversal) and three slope angles (0°/+7°/-7°). The results present detailed transport patterns of the three erosion agents under the varying soil and surface conditions up to a distance of 1.6 m. Under the applied rain intensity and wind velocity, wind-driven rain splash generates the highest erosion. The erodibility and travel distance of the two substrates depend on the erosion agent. The total erosion is slightly higher for the slope angle -7° (downslope), but for wind-driven rain splash, the inclination is not a relevant factor. The effect of surface structures (rills) changes with traveling distance. The wind driven rain splash generates a much higher amount of erosion and a further travel distance of the particles due to the combined action of wind and rain. The wind-driven rain factor appears to be much more significant than the other factors. The study highlights the effects of different erosion agents and surface parameters on short-distance particle transport and the powerful impact of wind-driven rain on soil erosion.

  4. Multi-scale wind erosion monitoring and assessment for US rangelands

    Science.gov (United States)

    Wind erosion is a major resource concern for rangeland managers. Although wind erosion is a naturally occurring process in many drylands, land use activities, and land management in particular, can accelerate wind-driven soil loss – impacting ecosystem dynamics and agricultural production, air quali...

  5. Wind erosion in the Sahelian zone of Niger : processes, models, and control techniques

    NARCIS (Netherlands)

    Sterk, G.

    1997-01-01

    In the Sahelian zone of Niger, severe wind erosion occurs mainly in the first half of the rainy season (May - July), when violent winds preceding thunderstorms result in intense sediment transport. Quantification of this wind erosion is difficult due to a high degree of temporal and spatial

  6. Early-season wind erosion influenced by soil-incorporated green manure in the Pacific Northwest

    Science.gov (United States)

    Management strategies are sought to minimize wind erosion of irrigated agricultural soils along the Columbia River of the Inland Pacific Northwest, particularly during the early season (March-April) when high winds coincide with sowing of vegetable crops. Early-season wind erosion potential from soi...

  7. Wind erosion potential of a winter wheat–summer fallow rotation after land application of biosolids

    Science.gov (United States)

    While land application of biosolids is recognized as a sustainable management practice for enhancing soil health, no studies have determined the effects of biosolids on soil wind erosion. Wind erosion potential of a silt loam was assessed using a portable wind tunnel after applying synthetic and bio...

  8. Wind erosion research at an uranium mill tailings site

    International Nuclear Information System (INIS)

    Sehmel, G.A.

    1977-07-01

    A uranium mill tailings pile at Grants, New Mexico, was selected for wind erosion research since the configuration provides flat area containing fine sand and made up of larger particles. The wind erosion experiment is discussed. Experimental equipment consists of meteorological instrumentation to automatically activate air samplers as a function of wind speed increments and direction, particle cascade impactors to measure airborne respirable concentrations as a function of particle size, inertial impaction devices to measure nonrespirable fluxes of airborne particles, a virtual particle cascade impactor to measure airborne concentrations of toxic trace elements, and soil depth gauges to measure changes in surface soil elevations as a function of time. Both radioactive particles as well as toxic trace element concentrations are measured. Radioactive particles are measured with both particle cascade impactors as well as high-volume air samplers. In contrast, toxic trace element airborne concentrations are measured only with a two-stage virtual particle cascade impactor. Fluxes of nonrespirable airborne particles are measured with inertial impaction devices. At particle cascade impactor sites, a rotating cyclone preseparator collects nonrespirable particles. In addition at all sites, fluxes of nonrespirable particles are measured using an open cavity inertial impaction device

  9. Manufacturing issues which affect coating erosion performance in wind turbine blades

    Science.gov (United States)

    Cortés, E.; Sánchez, F.; Domenech, L.; Olivares, A.; Young, T. M.; O'Carroll, A.; Chinesta, F.

    2017-10-01

    Erosion damage, caused by repeated rain droplet impact on the leading edges of wind turbine blades, is a major cause for cost concern. Resin Infusion (RI) is used in wind energy blades where low weight and high mechanical performance materials are demanded. The surface coating plays a crucial role in the manufacturing and performance response. The Leading Edge coating is usually moulded, painted or sprayed onto the blade surface so adequate adhesion in the layers' characterization through the thickness is required for mechanical performance and durability reasons. In the current work, an investigation has been directed into the resulting rain erosion durability of the coating was undertaken through a combination of mass loss testing measurements with manufacturing processing parameter variations. The adhesion and erosion is affected by the shock wave caused by the collapsing water droplet on impact. The stress waves are transmitted to the substrate, so microestructural discontinuities in coating layers and interfaces play a key role on its degradation. Standard industrial systems are based on a multilayer system, with a high number of interfaces that tend to accelerate erosion by delamination. Analytical and numerical models are commonly used to relate lifetime prediction and to identify suitable coating and composite substrate combinations and their potential stress reduction on the interface. In this research, the input parameters for the appropriate definition of the Cohesive Zone Modelling (CZM) of the coating-substrate interface are outlined by means of Pull off testing and Peeling testing results. It allowed one to optimize manufacturing and coating process for blades into a knowledge-based guidance for leading edge coating material development. It was achieved by investigating the erosion degradation process using both numerical and laboratory techniques (Pull off, Peeling and Rain Erosion Testing in a whirling arm rain erosion test facility).

  10. Spatial and temporal variations of wind erosion climatic erosivity in the farming-pastoral zone of Northern China

    Science.gov (United States)

    Yue, Shuping; Yang, Ruixin; Yan, Yechao; Yang, Zhengwei; Wang, Dandan

    2018-03-01

    Wind erosion climatic erosivity is an important parameter to assess the possible effects of climatic conditions on wind erosion. In this paper, the wind erosion climatic factor (C-factor), which was used to quantify the wind erosion climatic erosivity, was calculated for the period 1960-2014 based on monthly meteorological data collected from 101 stations in the farming-pastoral zone of Northern China. The Mann-Kendall (M-K) test, trend analysis, and geostatistical analysis methods were used to explore the spatial and temporal characteristics of the wind erosion climatic erosivity in this region. The result suggests that the annual C-factor, with a maximum of 76.05 in 1969 and a minimum of 26.57 in 2007, has a significant decreasing trend over the past 55 years. Strong seasonality in the C-factor was found, with the highest value in spring, which accounts for a significant proportion of the annual C-factor (41.46%). However, the coefficient of variation of the seasonal C-factor reaches a maximum in winter and a minimum in spring. The mean annual C-factor varies substantially across the region. Areas with high values of the mean annual C-factor (C ≥ 100) are located in Ulanqab and Dingxi, while areas with low values (C ≤ 10) lie in Lanzhou, Linxia, Dingxi, Xining, and Chengde. Spatial analysis on the trend of the C-factor reveals that 81% of the stations show statistically significant decreases at a 90% confidence level. An examination of the concentration ratio of the C-factor shows that the wind erosion climatic erosivity is concentrated in spring, especially in April, which makes this period particularly important for implementing soil conservation measures.

  11. Soil tillage and windbreak effects on millet and cowpea: I. Wind speed, evaporation, and wind erosion

    International Nuclear Information System (INIS)

    Banzhaf, J.; Leihner, D.E.; Buerkert, A.; Serafini, P.G.

    1992-01-01

    Deforestation, overgrazing, and declining soil regeneration periods have resulted in increased wind erosion problems in dry areas of the West African Sahel, but little is known about the bio-physical factors involved. This research was conducted to determine the effects of ridging and four different windbreak spacings on wind erosion, potential evaporation, and soil water reserves. A field trial was conducted from 1985 to 1987 on 12 ha of a Psammentic Paleustalf in Southern Niger. Millet, Pennisetum glaucum (L.), and cowpea, Vigna unguiculata (L.) Walp., were seeded in strips on flat and ridged soil. Windbreaks of savannah vegetation were spaced at 6, 20, 40, and 90 m. The effects of ridging on wind speed, evaporation, and wind erosion were small and mostly non-significant. However, average wind speed at 0.3 m above ground in the center of cowpea and millet strips was significantly reduced from 2.8 to 2.1 m s -1 as windbreak distances narrowed from 90 to 6 m. As a consequence, potential evaporation declined by 15% and the amount of windblown soil particles by 50% in ridged and by 70% in flat treatments. Despite reduced potential evaporation, average subsoil water reserves were 14 mm smaller in the 6- than in the 20-m windbreak spacing indicating excessive water extraction by the windbreak vegetation. Thus, establishing windbreaks with natural savannah vegetation may require a careful consideration of the agronomic benefits and costs to competing crops. 21 refs., 5 figs

  12. The combined effect of wind and rain on interrill erosion processes

    International Nuclear Information System (INIS)

    Erpul, G.; Gabriels, D.; Norton, L.D.

    2004-01-01

    flow-driven process begins to transport the detached soil particles. This is different from the approach of recent interrill erosion models that soil detached by the rain splash will be subsequently transported by overland flow. The results of the study showed that, when compared to the contribution of the flow-driven transport, the contribution of the rain splash transport was significant to the extent that it should not be neglected in accurately predicting water erosion from interrill areas under wind-driven rains

  13. Cavitation erosion prediction on Francis turbines

    Energy Technology Data Exchange (ETDEWEB)

    Bourdon, P.; Farhat, M.; Simoneau, R.; Lavigne, P. [Hydro-Quebec, Montreal, PQ (Canada); Pereira, F.; Dupont, P.; Avellan, F.; Caron, J.F. [IMHEF/EPFL, (France); Dorey, J.M.; Archer, A. [Electricite de France (EDF), 92 - Clamart (France). Dir. des Etudes et Recherches; and others

    1997-12-31

    On-board aggressiveness measurement methods were tested on a severely eroded prototype blade of a 266 MW Francis turbine: pressure, pit counting, DECER electrochemical and vibration measurements. The test program provided understanding of the heterogeneous erosion distribution of the prototype blades and quantitative data for comparison in subsequent tests on the model of the machine. Model tests and flow analysis were also performed, to detect cavitation on a Francis turbine model. The results are compared to those obtained on the prototype measurements. The model used for that study is built on the basis of a geometrical recovery of one of the most eroded blade of the prototype. Different methods were investigated to predict cavitation erosion on Francis turbines from model. They are based on measurement of pitting, pressure fluctuations and acceleration. The methods proposed are suitable to measure cavitation aggressiveness on model and on prototype, and that the level on the model is several orders of magnitude smaller than on the prototype. (author) 18 refs.

  14. Wind erosion potential of a winter wheat-summer fallow rotation after land application of biosolids

    Science.gov (United States)

    Pi, Huawei; Sharratt, Brenton; Schillinger, William F.; Bary, Andrew I.; Cogger, Craig G.

    2018-06-01

    Conservation tillage is a viable management strategy to control soil wind erosion, but other strategies such as land application of biosolids that enhance soil quality may also reduce wind erosion. No studies have determined the effects of biosolids on wind erosion. Wind erosion potential of a silt loam was assessed using a portable wind tunnel after applying synthetic and biosolids fertilizer to traditional (disk) and conservation (undercutter) tillage practices during the summer fallow phase of a winter wheat-summer fallow (WW-SF) rotation in 2015 and 2016 in east-central Washington. Soil loss ranged from 12 to 61% lower for undercutter than disk tillage, possibly due to retention of more biomass on the soil surface of the undercutter versus disk tillage treatment. In contrast, soil loss was similar to or lower for biosolids as compared with synthetic fertilizer treatment. Our results suggest that biosolids applications to agricultural lands will have minimal impact on wind erosion.

  15. Wind erosion control with scattered vegetation in the Sahelian zone of Burkina Faso

    NARCIS (Netherlands)

    Leenders, J.K.

    2006-01-01

    The Sahelian zone ofAfricais the region that is globally most subjected to land degradation, with wind erosion being the most important soil degradation process. By using control measures, the negative effects of wind erosion can be reduced. At present, adoption of

  16. Effect of vegetation cover and transitions on regional wind erosion in drylands

    NARCIS (Netherlands)

    Youssef, I.F.

    2012-01-01

    Wind erosion is a critical environmental problem that threatens mainly the arid and semi-arid regions of our planet. Usually this problem is associated with desertification, poverty and other environmental and socioeconomic problems. Wind erosion causes the loss of fertile topsoil, and has a

  17. Wind Erosion Processes and Control Techniques in the Sahelian Zone of Niger

    NARCIS (Netherlands)

    Sterk, G.; Stroosnijder, L.; Raats, P.A.C.

    1999-01-01

    Wind Erosion Processes and Control Techniques in the Sahelian Zone of Niger G. Sterk, L. Stroosnijder, and P.A.C. Raats Abstract The objective of this paper is to present the main results and conclusions from three years of field research on wind erosion processes and control techniques in the

  18. Farmers' perceptions of erosion by wind and water in northern Burkina Faso

    NARCIS (Netherlands)

    Visser, S.M.; Leenders, J.K.; Leeuwis, M.

    2003-01-01

    Wind and water erosion are widespread phenomena throughout the Sahel, especially in the early rainy season, when high-intensity rainstorms are often preceded by severe windstorms. This paper describes the results of a survey on the farmers' perceptions of wind and water erosion processes and control

  19. Geospatial application of the Water Erosion Prediction Project (WEPP) Model

    Science.gov (United States)

    D. C. Flanagan; J. R. Frankenberger; T. A. Cochrane; C. S. Renschler; W. J. Elliot

    2011-01-01

    The Water Erosion Prediction Project (WEPP) model is a process-based technology for prediction of soil erosion by water at hillslope profile, field, and small watershed scales. In particular, WEPP utilizes observed or generated daily climate inputs to drive the surface hydrology processes (infiltration, runoff, ET) component, which subsequently impacts the rest of the...

  20. The Current State of Predicting Furrow Irrigation Erosion

    Science.gov (United States)

    There continues to be a need to predict furrow irrigation erosion to estimate on- and off-site impacts of irrigation management. The objective of this paper is to review the current state of furrow erosion prediction technology considering four models: SISL, WEPP, WinSRFR and APEX. SISL is an empiri...

  1. Ecological site-based assessments of wind and water erosion: informing accelerated soil erosion management in rangelands

    Science.gov (United States)

    Webb, Nicholas P.; Herrick, Jeffrey E.; Duniway, Michael C.

    2014-01-01

    Accelerated soil erosion occurs when anthropogenic processes modify soil, vegetation or climatic conditions causing erosion rates at a location to exceed their natural variability. Identifying where and when accelerated erosion occurs is a critical first step toward its effective management. Here we explore how erosion assessments structured in the context of ecological sites (a land classification based on soils, landscape setting and ecological potential) and their vegetation states (plant assemblages that may change due to management) can inform systems for reducing accelerated soil erosion in rangelands. We evaluated aeolian horizontal sediment flux and fluvial sediment erosion rates for five ecological sites in southern New Mexico, USA, using monitoring data and rangeland-specific wind and water erosion models. Across the ecological sites, plots in shrub-encroached and shrub-dominated vegetation states were consistently susceptible to aeolian sediment flux and fluvial sediment erosion. Both processes were found to be highly variable for grassland and grass-succulent states across the ecological sites at the plot scale (0.25 Ha). We identify vegetation thresholds that define cover levels below which rapid (exponential) increases in aeolian sediment flux and fluvial sediment erosion occur across the ecological sites and vegetation states. Aeolian sediment flux and fluvial erosion in the study area can be effectively controlled when bare ground cover is 100 cm in length is less than ~35%. Land use and management activities that alter cover levels such that they cross thresholds, and/or drive vegetation state changes, may increase the susceptibility of areas to erosion. Land use impacts that are constrained within the range of natural variability should not result in accelerated soil erosion. Evaluating land condition against the erosion thresholds identified here will enable identification of areas susceptible to accelerated soil erosion and the development of

  2. Ecological site‐based assessments of wind and water erosion: informing accelerated soil erosion management in rangelands.

    Science.gov (United States)

    Webb, Nicholas P; Herrick, Jeffrey E; Duniway, Michael C

    Accelerated soil erosion occurs when anthropogenic processes modify soil, vegetation, or climatic conditions causing erosion rates at a location to exceed their natural variability. Identifying where and when accelerated erosion occurs is a critical first step toward its effective management. Here we explored how erosion assessments structured in the context of ecological sites (a land classification based on soils, landscape setting, and ecological potential) and their vegetation states (plant assemblages that may change due to management) can inform systems for reducing accelerated soil erosion in rangelands. We evaluated aeolian horizontal sediment flux and fluvial sediment erosion rates for five ecological sites in southern New Mexico, USA, using monitoring data and rangeland-specific wind and water erosion models. Across the ecological sites, plots in shrub-encroached and shrub-dominated vegetation states were consistently susceptible to aeolian sediment flux and fluvial sediment erosion. Both processes were found to be highly variable for grassland and grass–succulent states across the ecological sites at the plot scale (0.25 ha). We identified vegetation thresholds that define cover levels below which rapid (exponential) increases in aeolian sediment flux and fluvial sediment erosion occur across the ecological sites and vegetation states. Aeolian sediment flux and fluvial erosion in the study area could be effectively controlled when bare ground cover was 100 cm in length was less than ∼35%. Land use and management activities that alter cover levels such that they cross thresholds, and/or drive vegetation state changes, may increase the susceptibility of areas to erosion. Land use impacts that are constrained within the range of natural variability should not result in accelerated soil erosion. Evaluating land condition against the erosion thresholds identified here will enable identification of areas susceptible to accelerated soil erosion and the

  3. Response of wind erosion dynamics to climate change and human activity in Inner Mongolia, China during 1990 to 2015.

    Science.gov (United States)

    Zhang, Haiyan; Fan, Jiangwen; Cao, Wei; Harris, Warwick; Li, Yuzhe; Chi, Wenfeng; Wang, Suizi

    2018-10-15

    Soil erosion caused by wind is a serious environmental problem that results in land degradation and threatens sustainable development. Accurately evaluating wind erosion dynamics is important for reducing the hazard of wind erosion. Separating the climatic and anthropogenic causes of wind erosion can improve the understanding of its driving mechanisms. Based on meteorological, remote sensing and field observation data, we applied the Revised Wind Erosion Equation (RWEQ) to simulate wind erosion in Inner Mongolia, China from 1990 to 2015. We used the variable control method by input of the average climate conditions to calculate human-induced wind erosion. The difference between natural wind erosion and human-induced wind erosion was determined to assess the effect of climate change on wind erosion. The results showed that the wind erosion modulus had a remarkable decline with a slope of 52.23 t/km 2 /a from 1990 to 2015. During 26 years, the average wind erosion for Inner Mongolia amounted to 63.32 billion tons. Wind erosion showed an overall significant decline of 49.23% and the partial severer erosion hazard significantly increased by 7.11%. Of the significant regional decline, 40.72% was caused by climate changes, and 8.51% was attributed to ecological restoration programs. For the significant regional increases of wind erosion, 4.29% was attributed to climate changes and 2.82% to human activities, mainly overgrazing and land use/cover changes. During the study, the driving forces in Inner Mongolia of wind erosion dynamics differed spatially. Timely monitoring based on multi-source data and highlighting the importance of positive human activities by increasing vegetation coverage for deserts, reducing grazing pressure on grasslands, establishing forests as windbreaks and optimizing crop planting rotations of farmlands can all act to reduce and control wind erosion. Copyright © 2018 Elsevier B.V. All rights reserved.

  4. The development of U. S. soil erosion prediction and modeling

    Directory of Open Access Journals (Sweden)

    John M. Laflen

    2013-09-01

    Full Text Available Soil erosion prediction technology began over 70 years ago when Austin Zingg published a relationship between soil erosion (by water and land slope and length, followed shortly by a relationship by Dwight Smith that expanded this equation to include conservation practices. But, it was nearly 20 years before this work's expansion resulted in the Universal Soil Loss Equation (USLE, perhaps the foremost achievement in soil erosion prediction in the last century. The USLE has increased in application and complexity, and its usefulness and limitations have led to the development of additional technologies and new science in soil erosion research and prediction. Main among these new technologies is the Water Erosion Prediction Project (WEPP model, which has helped to overcome many of the shortcomings of the USLE, and increased the scale over which erosion by water can be predicted. Areas of application of erosion prediction include almost all land types: urban, rural, cropland, forests, rangeland, and construction sites. Specialty applications of WEPP include prediction of radioactive material movement with soils at a superfund cleanup site, and near real-time daily estimation of soil erosion for the entire state of Iowa.

  5. Application of fuzzy logic approach for wind erosion hazard mapping in Laghouat region (Algeria) using remote sensing and GIS

    Science.gov (United States)

    Saadoud, Djouher; Hassani, Mohamed; Martin Peinado, Francisco José; Guettouche, Mohamed Saïd

    2018-06-01

    Wind erosion is one of the most serious environmental problems in Algeria that threatens human activities and socio-economic development. The main goal of this study is to apply a fuzzy logic approach to wind erosion sensitivity mapping in the Laghouat region, Algeria. Six causative factors, obtained by applying fuzzy membership functions to each used parameter, are considered: soil, vegetation cover, wind factor, soil dryness, land topography and land cover sensitivity. Different fuzzy operators (AND, OR, SUM, PRODUCT, and GAMMA) are applied to generate wind-erosion hazard map. Success rate curves reveal that the fuzzy gamma (γ) operator, with γ equal to 0.9, gives the best prediction accuracy with an area under curve of 85.2%. The resulting wind-erosion sensitivity map delineates the area into different zones of five relative sensitivity classes: very high, high, moderate, low and very low. The estimated result was verified by field measurements and the high statistically significant value of a chi-square test.

  6. Understanding and Predicting Gun Barrel Erosion

    National Research Council Canada - National Science Library

    Johnston, Ian A

    2005-01-01

    The Australian Defence Force will soon have to contend with gun barrel erosion issues arising from the use of new low-vulnerability gun propellants, the acquisition of new ammunition and gun systems...

  7. [Estimation of the effect derived from wind erosion of soil and dust emission in Tianjin suburbs on the central district based on WEPS model].

    Science.gov (United States)

    Chen, Li; Han, Ting-Ting; Li, Tao; Ji, Ya-Qin; Bai, Zhi-Peng; Wang, Bin

    2012-07-01

    Due to the lack of a prediction model for current wind erosion in China and the slow development for such models, this study aims to predict the wind erosion of soil and the dust emission and develop a prediction model for wind erosion in Tianjin by investigating the structure, parameter systems and the relationships among the parameter systems of the prediction models for wind erosion in typical areas, using the U.S. wind erosion prediction system (WEPS) as reference. Based on the remote sensing technique and the test data, a parameter system was established for the prediction model of wind erosion and dust emission, and a model was developed that was suitable for the prediction of wind erosion and dust emission in Tianjin. Tianjin was divided into 11 080 blocks with a resolution of 1 x 1 km2, among which 7 778 dust emitting blocks were selected. The parameters of the blocks were localized, including longitude, latitude, elevation and direction, etc.. The database files of blocks were localized, including wind file, climate file, soil file and management file. The weps. run file was edited. Based on Microsoft Visualstudio 2008, secondary development was done using C + + language, and the dust fluxes of 7 778 blocks were estimated, including creep and saltation fluxes, suspension fluxes and PM10 fluxes. Based on the parameters of wind tunnel experiments in Inner Mongolia, the soil measurement data and climate data in suburbs of Tianjin, the wind erosion module, wind erosion fluxes, dust emission release modulus and dust release fluxes were calculated for the four seasons and the whole year in suburbs of Tianjin. In 2009, the total creep and saltation fluxes, suspension fluxes and PM10 fluxes in the suburbs of Tianjin were 2.54 x 10(6) t, 1.25 x 10(7) t and 9.04 x 10(5) t, respectively, among which, the parts pointing to the central district were 5.61 x 10(5) t, 2.89 x 10(6) t and 2.03 x 10(5) t, respectively.

  8. Water erosion risk prediction in eucalyptus plantations

    Directory of Open Access Journals (Sweden)

    Mayesse Aparecida da Silva

    2014-04-01

    Full Text Available Eucalyptus plantations are normally found in vulnerable ecosystems such as steep slope, soil with low natural fertility and lands that were degraded by agriculture. The objective of this study was to obtain Universal Soil Loss Equation (USLE factors and use them to estimate water erosion risk in regions with eucalyptus planted. The USLE factors were obtained in field plots under natural rainfall in the Rio Doce Basin, MG, Brazil, and the model applied to assess erosion risk using USLE in a Geographic Information System. The study area showed rainfall-runoff erosivity values from 10,721 to 10,642 MJ mm ha-1 h-1 yr-1. Some soils (Latosols had very low erodibility values (2.0 x 10-4 and 1.0 x 10-4t h MJ-1 mm-1, the topographic factor ranged from 0.03 to 10.57 and crop and management factor values obtained for native forest, eucalyptus and planted pasture were 0.09, 0.12 and 0.22, respectively. Water erosion risk estimates for current land use indicated that the areas where should receive more attention were mainly areas with greater topographic factors and those with Cambisols. Planning of forestry activities in this region should consider implementation of other conservation practices beyond those already used, reducing areas with a greater risk of soil erosion and increasing areas with very low risk.

  9. Predicting of soil erosion with regarding to rainfall erosivity and soil erodibility

    Science.gov (United States)

    Suif, Zuliziana; Razak, Mohd Amirun Anis Ab; Ahmad, Nordila

    2018-02-01

    The soil along the hill and slope are wearing away due to erosion and it can take place due to occurrence of weak and heavy rainfall. The aim of this study is to predict the soil erosion degree in Universiti Pertahanan Nasional Malaysia (UPNM) area focused on two major factor which is soil erodibility and rainfall erosivity. Soil erodibility is the possibilities of soil to detach and carried away during rainfall and runoff. The "ROM" scale was used in this study to determine the degree of soil erodibility, namely low, moderate, high, and very high. As for rainfall erosivity, the erosive power caused by rainfall that cause soil loss. A daily rainfall data collected from January to April was analyzed by using ROSE index classification to identify the potential risk of soil erosion. The result shows that the soil erodibilty are moderate at MTD`s hill, high at behind of block Lestari and Landslide MTD hill, and critical at behind the mess cadet. While, the highest rainfall erosivity was recorded in March and April. Overall, this study would benefit the organization greatly in saving cost in landslide protection as relevant authorities can take early measures repairing the most affected area of soil erosion.

  10. Predicción de la erosión eólica potencial con el modelo EWEQ en dos suelos loesicos: efectos de las condiciones climáticas Wind erosion prediction with the EWEQ model in two loess soils: effects of climatic condition

    Directory of Open Access Journals (Sweden)

    Silvia Beatriz Aimar

    2011-12-01

    Full Text Available La erosión eólica potencial del suelo (EEP es un dato básico utilizado en varios modelos de predicción para calcular la erosión eólica de suelos agrícolas. El objetivo de este estudio fue cuantificar la EEP de un Haplustol y un Ustipsammente de la Región Semiárida Pampeana (RSP y compararla con las predicciones del modelo Ecuación de Erosión Eólica en Español (EWEQ, realizadas con diferentes factores climáticos (C. Se efectuaron mediciones de EEP a campo durante un año en ambos suelos, mantenidos sin cobertura y con mínima rugosidad. Los resultados indicaron que la EEP medida a campo fue mayor en el Ustipsammente (270 Mg ha-1 año-1 que en el Haplustol (40 Mg ha-1 año -1 , con una reducción en el espesor del horizonte de 21,3 y 3,1 mm, respectivamente. La erosión del Ustipsammente fue dos veces mayor en primavera-verano que en otoño-invierno. Este efecto no se observó en el Haplustol, debido a su menor desecamiento y mayores contenidos de humedad luego de las lluvias. La erosión del Haplustol, por desecarse más lentamente luego de una lluvia, fue más condicionada por las precipitaciones que la del Ustipsammente. Un 40% de la erosión de ambos suelos fue definida por la duración de las tormentas. Las tasas de erosión (EEP por unidad de tiempo, Qt se correlacionaron positivamente con la velocidad promedio del viento (V, ajustando a una función polinómica en ambos suelos. A la misma V, Qt fue siempre mayor en el Ustipsammente. La EEP calculada con la EWEQ, utilizando el factor C correspondiente al año de muestreo (30,3, fue la más semejante a la erosión medida a campo, aunque el modelo la subestimó en un 43% en el Haplustol y en un 18% en el Ustipsammente. La EWEQ deberá ofrecer al usuario distintos factores C para poder predecir EEP en escenarios climáticos variables.The potential wind erosion of a soil (EEP is a basic data for predicting wind erosion of agricultural soils in most wind erosion prediction models

  11. On the Predictability of Hub Height Winds

    DEFF Research Database (Denmark)

    Draxl, Caroline

    Wind energy is a major source of power in over 70 countries across the world, and the worldwide share of wind energy in electricity consumption is growing. The introduction of signicant amounts of wind energy into power systems makes accurate wind forecasting a crucial element of modern electrical...... grids. These systems require forecasts with temporal scales of tens of minutes to a few days in advance at wind farm locations. Traditionally these forecasts predict the wind at turbine hub heights; this information is then converted by transmission system operators and energy companies into predictions...... of power output at wind farms. Since the power available in the wind is proportional to the wind speed cubed, even small wind forecast errors result in large power prediction errors. Accurate wind forecasts are worth billions of dollars annually; forecast improvements will result in reduced costs...

  12. Wind erosion on Deliblato (the largest European continental sandy terrain) studied using 210Pbex and 137Cs measurements

    International Nuclear Information System (INIS)

    Krmar, M.; Hansman, J.; Todorovic, N.; Mihailovic, A.; Vucinic-Vasic, M.; Savic, R.

    2015-01-01

    The objective of this paper is to estimate the difference in wind erosion between two extreme situations: sandy soil permanently covered by grass and the nearby frequently ploughed area highly susceptible to wind erosion. The spatial pattern of soil erosion rate was investigated using 137 Cs and 210 Pb ex tracing technique. The spatial pattern of erosion rate obtained within the studied area reveal influence of topography as well as direction of prevailing winds on mobilization and transport of the soil particles. (author)

  13. A New Instrument for Testing Wind Erosion by Soil Surface Shape Change

    International Nuclear Information System (INIS)

    Hai, C.; Yuan, X.; Jiang, H.; Zhou, R.; Wang, J.; Liu, B.; Ye, Y.; Du, P.

    2010-01-01

    Wind erosion, a primary cause of soil degeneration, is a problem in arid and semiarid areas throughout the world. Many methods are available to study soil erosion, but there is no an effective method for making quantitative measurements in the field. To solve this problem, we have developed a new instrument that can measure the change in the shape of the soil surface, allowing quick quantification of wind erosion. In this paper, the construction and principle of the new instrument are described. Field experiments are carried out using the instrument, and the data are analyzed. The erosion depth is found to vary by 11% compared to the average for measurement areas ranging from 30 x 30 cm 2 to 10 x 10 cm 2 . The results show that the instrument is convenient and reliable for quantitatively measuring wind erosion in the field.

  14. Wind born(e) landscapes: the role of wind erosion in agricultural land management and nature development

    NARCIS (Netherlands)

    Riksen, M.J.P.M.

    2006-01-01

    Wind has played an important role in the geological development of the north-western Europe. Various aeolian deposits such as inland dunes, river dunes, cover sands, drift sands and coastal dunes, form the base of large areas in our present landscape. The role of wind erosion in today's north-west

  15. Quantifying accelerated soil erosion through ecological site-based assessments of wind and water erosion

    Science.gov (United States)

    This work explores how organising soil erosion assessments using established groupings of similar soils (ecological sites) can inform systems for managing accelerated soil erosion. We evaluated aeolian sediment transport and fluvial erosion rates for five ecological sites in southern New Mexico, USA...

  16. Wind Power Prediction Considering Nonlinear Atmospheric Disturbances

    Directory of Open Access Journals (Sweden)

    Yagang Zhang

    2015-01-01

    Full Text Available This paper considers the effect of nonlinear atmospheric disturbances on wind power prediction. A Lorenz system is introduced as an atmospheric disturbance model. Three new improved wind forecasting models combined with a Lorenz comprehensive disturbance are put forward in this study. Firstly, we define the form of the Lorenz disturbance variable and the wind speed perturbation formula. Then, different artificial neural network models are used to verify the new idea and obtain better wind speed predictions. Finally we separately use the original and improved wind speed series to predict the related wind power. This proves that the corrected wind speed provides higher precision wind power predictions. This research presents a totally new direction in the wind prediction field and has profound theoretical research value and practical guiding significance.

  17. Leading edge erosion of coated wind turbine blades: Review of coating life models

    NARCIS (Netherlands)

    Slot, H.M.; Gelinck, E.R.M.; Rentrop, A.; van der Heide, Emile

    2015-01-01

    Erosion of the leading edge of wind turbine blades by droplet impingement wear, reduces blade aerodynamic efficiency and power output. Eventually, it compromises the integrity of blade surfaces. Elastomeric coatings are currently used for erosion resistance, yet the life of such coatings cannot be

  18. An extreme wind erosion event of the fresh Eyjafjallajökull 2010 volcanic ash.

    Science.gov (United States)

    Arnalds, Olafur; Thorarinsdottir, Elin Fjola; Thorsson, Johann; Waldhauserova, Pavla Dagsson; Agustsdottir, Anna Maria

    2013-01-01

    Volcanic eruptions can generate widespread deposits of ash that are subsequently subjected to erosive forces which causes detrimental effects on ecosystems. We measured wind erosion of the freshly deposited Eyjafjallajökull ash at a field site the first summer after the 2010 eruption. Over 30 wind erosion events occurred (June-October) at wind speeds > 10 m s(-1) in each storm with gusts up to 38.7 m s(-1). Surface transport over one m wide transect (surface to 150 cm height) reached > 11,800 kg m(-1) during the most intense storm event with a rate of 1,440 kg m(-1) hr(-1) for about 6½ hrs. This storm is among the most extreme wind erosion events recorded on Earth. The Eyjafjallajökull wind erosion storms caused dust emissions extending several hundred km from the volcano affecting both air quality and ecosystems showing how wind erosion of freshly deposited ash prolongs impacts of volcanic eruptions.

  19. Conditional prediction intervals of wind power generation

    DEFF Research Database (Denmark)

    Pinson, Pierre; Kariniotakis, Georges

    2010-01-01

    A generic method for the providing of prediction intervals of wind power generation is described. Prediction intervals complement the more common wind power point forecasts, by giving a range of potential outcomes for a given probability, their so-called nominal coverage rate. Ideally they inform...... on the characteristics of prediction errors for providing conditional interval forecasts. By simultaneously generating prediction intervals with various nominal coverage rates, one obtains full predictive distributions of wind generation. Adapted resampling is applied here to the case of an onshore Danish wind farm...... to the case of a large number of wind farms in Europe and Australia among others is finally discussed....

  20. Theoretical model for cavitation erosion prediction in centrifugal pump impeller

    International Nuclear Information System (INIS)

    Rayan, M.A.; Mahgob, M.M.; Mostafa, N.H.

    1990-01-01

    Cavitation is known to have great effects on pump hydraulic and mechanical characteristics. These effects are mainly described by deviation in pump performance, increasing vibration and noise level as well as erosion of blade and casing materials. In the present work, only the hydrodynamic aspect of cavitation was considered. The efforts were directed toward the study of cavitation inception, cavity mechanics and material erosion in order to clarify the macrohydrodynamic aspects of cavitation erosive wear in real machines. As a result of this study, it was found that cavitation damage can be predicted from model data. The obtained theoretical results show good agreement with the experimental results obtained in this investigation and with results of some other investigations. The application of the findings of this work will help the design engineer in predicting the erosion rate, according to the different operating conditions. (author)

  1. Deterministic prediction of surface wind speed variations

    Directory of Open Access Journals (Sweden)

    G. V. Drisya

    2014-11-01

    Full Text Available Accurate prediction of wind speed is an important aspect of various tasks related to wind energy management such as wind turbine predictive control and wind power scheduling. The most typical characteristic of wind speed data is its persistent temporal variations. Most of the techniques reported in the literature for prediction of wind speed and power are based on statistical methods or probabilistic distribution of wind speed data. In this paper we demonstrate that deterministic forecasting methods can make accurate short-term predictions of wind speed using past data, at locations where the wind dynamics exhibit chaotic behaviour. The predictions are remarkably accurate up to 1 h with a normalised RMSE (root mean square error of less than 0.02 and reasonably accurate up to 3 h with an error of less than 0.06. Repeated application of these methods at 234 different geographical locations for predicting wind speeds at 30-day intervals for 3 years reveals that the accuracy of prediction is more or less the same across all locations and time periods. Comparison of the results with f-ARIMA model predictions shows that the deterministic models with suitable parameters are capable of returning improved prediction accuracy and capturing the dynamical variations of the actual time series more faithfully. These methods are simple and computationally efficient and require only records of past data for making short-term wind speed forecasts within practically tolerable margin of errors.

  2. PM2.5 and PM10 Emission from agricultural soils by wind erosion

    Science.gov (United States)

    Soil tillage and wind erosion are a major source of particulate matter less than 2.5 and 10 µm (PM2.5 and PM10) emission from cultivated soil. Fifteen cultivated soils collected from 5 states were tested as crushed (<2.0 mm) and uncrushed (natural aggregation) at 8, 10, and 13 m s-1 wind velocity in...

  3. Soil erosion rates from mixed soil and gravel surfaces in a wind tunnel: A preliminary report

    International Nuclear Information System (INIS)

    Ligotke, M.W.

    1988-12-01

    Tests of wind erosion were performed in a controlled-environment wind tunnel to support the development of natural-material protective barriers for long-term isolation of radioactive waste. Barrier performance standards currently being developed for internal and external barrier performance are expected to mandate a surface layer that is resistant to wind erosion. The purpose of this study was to initiate a series of tests to determine suitable soil and gravel mixtures for such a barrier and to test worst-case surface layer conditions under the influence of high wind speeds. Six mixed soil and gravel surfaces were prepared, weathered to represent natural wind-blown desert areas, and subjected to controlled wind erosion forces in a wind tunnel. The applied erosive forces, including surface shear forces, were characterized to provide a means of relating wind tunnel results with actual field conditions. Soil particle losses from the surfaces caused by suspension, saltation, and surface creep were monitored by aerosol sample probes and mass balance measurements. 23 refs., 22 figs., 3 tabs

  4. Erosion prediction for alpine slopes: a symbiosis of remote sensing and a physical based erosion model

    Science.gov (United States)

    Kaiser, Andreas; Neugirg, Fabian; Haas, Florian; Schindewolf, Marcus; Schmidt, Jürgen

    2014-05-01

    As rainfall simulations represent an established tool for quantifying soil detachment on cultivated area in lowlands and low mountain ranges, they are rarely used on steep slopes high mountain ranges. Still this terrain represents productive sediment sources of high morphodynamic. A quantitative differentiation between gravitationally and fluvially relocated material reveals a major challenge in understanding erosion on steep slopes: does solifluction as a result of melting in spring or heavy convective rainstorms during summer cause the essential erosion processes? This paper aims to answer this question by separating gravitational mass movement (solifluction, landslides, mudflow and needle ice) and runoff-induced detachment. First simulated rainstorm experiments are used to assess the sediment production on bare soil on a strongly inclined plot (1 m², 42°) in the northern limestone Alps. Throughout precipitation experiments runoff and related suspended sediments were quantified. In order to enlarge slope length virtually to around 20 m a runoff feeding device is additionally implemented. Soil physical parameters were derived from on-site sampling. The generated data is introduced to the physically based and catchment-scaled erosion model EROSION 3D to upscale plot size to small watershed conditions. Thus infiltration, runoff, detachment, transport and finally deposition can be predicted for single rainstorm events and storm sequences. Secondly, in order to separate gravitational mass movements and water erosion, a LiDAR and structure-from-motion based monitoring approach is carried out to produce high-resolution digital elevation models. A time series analysis of detachment and deposition from different points in time is implemented. Absolute volume losses are then compared to sediment losses calculated by the erosion model as the latter only generates data that is connected to water induced hillside erosion. This methodology will be applied in other watersheds

  5. The Dust Storm Index (DSI): A method for monitoring broadscale wind erosion using meteorological records

    Science.gov (United States)

    O'Loingsigh, T.; McTainsh, G. H.; Tews, E. K.; Strong, C. L.; Leys, J. F.; Shinkfield, P.; Tapper, N. J.

    2014-03-01

    Wind erosion of soils is a natural process that has shaped the semi-arid and arid landscapes for millennia. This paper describes the Dust Storm Index (DSI); a methodology for monitoring wind erosion using Australian Bureau of Meteorology (ABM) meteorological observational data since the mid-1960s (long-term), at continental scale. While the 46 year length of the DSI record is its greatest strength from a wind erosion monitoring perspective, there are a number of technical challenges to its use because when the World Meteorological Organisation (WMO) recording protocols were established the use of the data for wind erosion monitoring was never intended. Data recording and storage protocols are examined, including the effects of changes to the definition of how observers should interpret and record dust events. A method is described for selecting the 180 long-term ABM stations used in this study and the limitations of variable observation frequencies between stations are in part resolved. The rationale behind the DSI equation is explained and the examples of temporal and spatial data visualisation products presented include; a long term national wind erosion record (1965-2011), continental DSI maps, and maps of the erosion event types that are factored into the DSI equation. The DSI is tested against dust concentration data and found to provide an accurate representation of wind erosion activity. As the ABM observational records used here were collected according to WMO protocols, the DSI methodology could be used in all countries with WMO-compatible meteorological observation and recording systems.

  6. Geospatial application of the Water Erosion Prediction Project (WEPP) model

    Science.gov (United States)

    D. C. Flanagan; J. R. Frankenberger; T. A. Cochrane; C. S. Renschler; W. J. Elliot

    2013-01-01

    At the hillslope profile and/or field scale, a simple Windows graphical user interface (GUI) is available to easily specify the slope, soil, and management inputs for application of the USDA Water Erosion Prediction Project (WEPP) model. Likewise, basic small watershed configurations of a few hillslopes and channels can be created and simulated with this GUI. However,...

  7. Using Cesium-137 technique to study the characteristics of different aspect of soil erosion in the Wind-water Erosion Crisscross Region on Loess Plateau of China

    International Nuclear Information System (INIS)

    Li Mian; Li Zhanbin; Liu Puling; Yao Wenyi

    2005-01-01

    The most serious soil erosion on Loess Plateau exists in the Wind-water Erosion Crisscross Region. In the past 20 years, the types and intensity of soil erosion and its temporal and spatial distribution were studied, but studies on the difference of soil erosion between slope aspects and slope positions in this area have no report. However, it is very important to analyze and evaluate quantitatively the characteristics of different aspects and positions of soil loss for the prevention and treatment of soil erosion in this area. The spatial pattern of net soil loss on 4 downslope transects in four aspects (east, west, south and north) on a typical Mao (round loess mound) in Liudaogou catchment in Wind-water Erosion Crisscross Region was measured in 2000 using the resident cesium-137 deficit technique. The purposes of this investigation were undertaken to determine whether or not 137 Cs measurement would give a useful indication of the extent of soil loss and their characteristics from cultivated hillsides in different slope aspect and slope position in the study area. The results showed that the difference of soil erosion in different aspect was significant and the erosion rate was in this order: north>east>south>west. Compared with other areas, the difference of erosion rate between north hillside and south hillside was on the contrary, and the possible explanations could be the effect of wind erosion. Also, the percentage of wind erosion was estimated to be at least larger than 18% of total soil loss by comparing the difference of erosion amount in south hillside and north hillside. The erosion rates on different slope positions in all aspects were also different, the highest net soil loss occurred in the lower slope position, and the upper and middle slope positions were slight. The general trend of net soil loss on sloping surface was to increase in fluctuation with increasing downslope distance

  8. Using Cesium-137 technique to study the characteristics of different aspect of soil erosion in the Wind-water Erosion Crisscross Region on Loess Plateau of China

    Energy Technology Data Exchange (ETDEWEB)

    Li Mian E-mail: hnli-mian@163.com; Li Zhanbin; Liu Puling; Yao Wenyi

    2005-01-01

    The most serious soil erosion on Loess Plateau exists in the Wind-water Erosion Crisscross Region. In the past 20 years, the types and intensity of soil erosion and its temporal and spatial distribution were studied, but studies on the difference of soil erosion between slope aspects and slope positions in this area have no report. However, it is very important to analyze and evaluate quantitatively the characteristics of different aspects and positions of soil loss for the prevention and treatment of soil erosion in this area. The spatial pattern of net soil loss on 4 downslope transects in four aspects (east, west, south and north) on a typical Mao (round loess mound) in Liudaogou catchment in Wind-water Erosion Crisscross Region was measured in 2000 using the resident cesium-137 deficit technique. The purposes of this investigation were undertaken to determine whether or not {sup 137}Cs measurement would give a useful indication of the extent of soil loss and their characteristics from cultivated hillsides in different slope aspect and slope position in the study area. The results showed that the difference of soil erosion in different aspect was significant and the erosion rate was in this order: north>east>south>west. Compared with other areas, the difference of erosion rate between north hillside and south hillside was on the contrary, and the possible explanations could be the effect of wind erosion. Also, the percentage of wind erosion was estimated to be at least larger than 18% of total soil loss by comparing the difference of erosion amount in south hillside and north hillside. The erosion rates on different slope positions in all aspects were also different, the highest net soil loss occurred in the lower slope position, and the upper and middle slope positions were slight. The general trend of net soil loss on sloping surface was to increase in fluctuation with increasing downslope distance.

  9. Bayesian Predictive Models for Rayleigh Wind Speed

    DEFF Research Database (Denmark)

    Shahirinia, Amir; Hajizadeh, Amin; Yu, David C

    2017-01-01

    predictive model of the wind speed aggregates the non-homogeneous distributions into a single continuous distribution. Therefore, the result is able to capture the variation among the probability distributions of the wind speeds at the turbines’ locations in a wind farm. More specifically, instead of using...... a wind speed distribution whose parameters are known or estimated, the parameters are considered as random whose variations are according to probability distributions. The Bayesian predictive model for a Rayleigh which only has a single model scale parameter has been proposed. Also closed-form posterior...... and predictive inferences under different reasonable choices of prior distribution in sensitivity analysis have been presented....

  10. Wind Erosion Induced Soil Degradation in Northern China: Status, Measures and Perspective

    Directory of Open Access Journals (Sweden)

    Zhongling Guo

    2014-12-01

    Full Text Available Soil degradation is one of the most serious ecological problems in the world. In arid and semi-arid northern China, soil degradation predominantly arises from wind erosion. Trends in soil degradation caused by wind erosion in northern China frequently change with human activities and climatic change. To decrease soil loss by wind erosion and enhance local ecosystems, the Chinese government has been encouraging residents to reduce wind-induced soil degradation through a series of national policies and several ecological projects, such as the Natural Forest Protection Program, the National Action Program to Combat Desertification, the “Three Norths” Shelter Forest System, the Beijing-Tianjin Sand Source Control Engineering Project, and the Grain for Green Project. All these were implemented a number of decades ago, and have thus created many land management practices and control techniques across different landscapes. These measures include conservation tillage, windbreak networks, checkerboard barriers, the Non-Watering and Tube-Protecting Planting Technique, afforestation, grassland enclosures, etc. As a result, the aeolian degradation of land has been controlled in many regions of arid and semiarid northern China. However, the challenge of mitigating and further reversing soil degradation caused by wind erosion still remains.

  11. Remote sensing of land use/cover changes and its effect on wind erosion potential in southern Iran

    NARCIS (Netherlands)

    Rezaei, Mahrooz; Sameni, Abdolmajid; Fallah Shamsi, Seyed Rashid; Bartholomeus, Harm

    2016-01-01

    Wind erosion is a complex process influenced by different factors. Most of these factors are stable over time, but land use/cover and land management practices are changing gradually. Therefore, this research investigates the impact of changing land use/cover and land management on wind erosion

  12. Wind erosion potential influenced by tillage in an irrigated potato-sweet corn rotation in the Columbia Basin

    Science.gov (United States)

    Wind erosion is a concern within the Columbia Basin of the Inland Pacific Northwest (PNW) United States due to the sandy texture of soils and small amount of residue retained on the soil surface after harvest of vegetable crops like potato. This study assessed potential wind erosion of an irrigated ...

  13. Wind farms production: Control and prediction

    Science.gov (United States)

    El-Fouly, Tarek Hussein Mostafa

    Wind energy resources, unlike dispatchable central station generation, produce power dependable on external irregular source and that is the incident wind speed which does not always blow when electricity is needed. This results in the variability, unpredictability, and uncertainty of wind resources. Therefore, the integration of wind facilities to utility electrical grid presents a major challenge to power system operator. Such integration has significant impact on the optimum power flow, transmission congestion, power quality issues, system stability, load dispatch, and economic analysis. Due to the irregular nature of wind power production, accurate prediction represents the major challenge to power system operators. Therefore, in this thesis two novel models are proposed for wind speed and wind power prediction. One proposed model is dedicated to short-term prediction (one-hour ahead) and the other involves medium term prediction (one-day ahead). The accuracy of the proposed models is revealed by comparing their results with the corresponding values of a reference prediction model referred to as the persistent model. Utility grid operation is not only impacted by the uncertainty of the future production of wind farms, but also by the variability of their current production and how the active and reactive power exchange with the grid is controlled. To address this particular task, a control technique for wind turbines, driven by doubly-fed induction generators (DFIGs), is developed to regulate the terminal voltage by equally sharing the generated/absorbed reactive power between the rotor-side and the gridside converters. To highlight the impact of the new developed technique in reducing the power loss in the generator set, an economic analysis is carried out. Moreover, a new aggregated model for wind farms is proposed that accounts for the irregularity of the incident wind distribution throughout the farm layout. Specifically, this model includes the wake effect

  14. Literature review of models for estimating soil erosion and deposition from wind stresses on uranium-mill-tailings covers

    Energy Technology Data Exchange (ETDEWEB)

    Bander, T.J.

    1982-11-01

    Pacific Northwest Laboratory (PNL) is investigating the use of a rock armoring blanket (riprap) to mitigate wind and water erosion of an earthen radon-suppression cover applied to uranium-mill tailings. The mechanics of wind erosion, as well as of soil deposition, are discussed in this report. Several wind erosion models are reviewed to determine if they can be used to estimate the erosion of soil from a mill-tailings cover. One model, developed by W.S. Chepil, contains the most-important factors that describe variables that influence wind erosion. Particular features of other models are also discussed, as well as the application of Chepil's model to a particular tailings pile. For this particular tailings pile, the estimated erosion was almost one inch per year for an unprotected tailings soil surface. Wide variability in the deposition velocity and lack of adequate deposition models preclude reliable estimates of the rate at which airborne particles are deposited.

  15. Literature review of models for estimating soil erosion and deposition from wind stresses on uranium-mill-tailings covers

    International Nuclear Information System (INIS)

    Bander, T.J.

    1982-11-01

    Pacific Northwest Laboratory (PNL) is investigating the use of a rock armoring blanket (riprap) to mitigate wind and water erosion of an earthen radon-suppression cover applied to uranium-mill tailings. The mechanics of wind erosion, as well as of soil deposition, are discussed in this report. Several wind erosion models are reviewed to determine if they can be used to estimate the erosion of soil from a mill-tailings cover. One model, developed by W.S. Chepil, contains the most-important factors that describe variables that influence wind erosion. Particular features of other models are also discussed, as well as the application of Chepil's model to a particular tailings pile. For this particular tailings pile, the estimated erosion was almost one inch per year for an unprotected tailings soil surface. Wide variability in the deposition velocity and lack of adequate deposition models preclude reliable estimates of the rate at which airborne particles are deposited

  16. Predicting coastal cliff erosion using a Bayesian probabilistic model

    Science.gov (United States)

    Hapke, Cheryl J.; Plant, Nathaniel G.

    2010-01-01

    Regional coastal cliff retreat is difficult to model due to the episodic nature of failures and the along-shore variability of retreat events. There is a growing demand, however, for predictive models that can be used to forecast areas vulnerable to coastal erosion hazards. Increasingly, probabilistic models are being employed that require data sets of high temporal density to define the joint probability density function that relates forcing variables (e.g. wave conditions) and initial conditions (e.g. cliff geometry) to erosion events. In this study we use a multi-parameter Bayesian network to investigate correlations between key variables that control and influence variations in cliff retreat processes. The network uses Bayesian statistical methods to estimate event probabilities using existing observations. Within this framework, we forecast the spatial distribution of cliff retreat along two stretches of cliffed coast in Southern California. The input parameters are the height and slope of the cliff, a descriptor of material strength based on the dominant cliff-forming lithology, and the long-term cliff erosion rate that represents prior behavior. The model is forced using predicted wave impact hours. Results demonstrate that the Bayesian approach is well-suited to the forward modeling of coastal cliff retreat, with the correct outcomes forecast in 70–90% of the modeled transects. The model also performs well in identifying specific locations of high cliff erosion, thus providing a foundation for hazard mapping. This approach can be employed to predict cliff erosion at time-scales ranging from storm events to the impacts of sea-level rise at the century-scale.

  17. Evaluation of chemical stabilizers and windscreens for wind erosion control of uranium mill tailings

    International Nuclear Information System (INIS)

    Elmore, M.R.; Hartley, J.N.

    1984-08-01

    Potential wind erosion of uranium mill tailings is a concern for the surface disposal of tailings at uranium mills. Wind-blown tailings may subsequently be redeposited on areas outside the impoundment. Pacific Northwest Laboratory (PNL) is investigating techniques for fugitive dust control at uranium mill tailings piles. Laboratory tests, including wind tunnel studies, were conducted to evaluate the relative effectiveness of 43 chemical stabilizers. Seventeen of the more promising stabilizers were applied to test plots on a uranium tailings pile at the American Nuclear Corporation-Gas Hills Project mill site in central Wyoming. The durabilities of these materials under actual site conditions were evaluated over time. In addition, field testing of commercially available windscreens was conducted. Test panels were constructed of eight different materials at the Wyoming test site to compare their durability. A second test site was established near PNL to evaluate the effectiveness of windscreens at reducing wind velocity, and thereby reduce the potential for wind erosion of mill tailings. Results of the laboratory land field tests of the chemical stabilizers and windscreens are presented, along with costs versus effectiveness of these techniques for control of wind erosion at mill tailings piles. 12 references, 4 figures, 6 tables

  18. Interactions Between Wind Erosion, Vegetation Structure, and Soil Stability in Groundwater Dependent Plant Communities

    Science.gov (United States)

    Vest, K. R.; Elmore, A. J.; Okin, G. S.

    2009-12-01

    Desertification is a human induced global phenomenon causing a loss of biodiversity and ecosystem productivity. Semi-arid grasslands are vulnerable to anthropogenic impacts (i.e., groundwater pumping and surface water diversion) that decrease vegetation cover and increase bare soil area leading to a greater probability of soil erosion, potentially enhancing feedback processes associated with desertification. To enhance our understanding of interactions between anthropogenic, physical, and biological factors causing desertification, this study used a combination of modeling and field observations to examine the relationship between chronic groundwater pumping and vegetation cover change and its effects on soil erosion and stability. The work was conducted in Owens Valley California, where a long history of groundwater pumping and surface water diversion has lead to documented vegetation changes. The work examined hydrological, ecological and biogeochemical factors across thirteen sites in Owens Valley. We analyzed soil stability, vegetation and gap size, soil organic carbon, and we also installed Big Spring Number Eight (BSNE) catchers to calculate mass transport of aeolian sediment across sites. Mass transport calculations were used to validate a new wind erosion model that represents the effect of porous vegetation on surface windshear velocity. Results across two field seasons show that the model can be used to predict mass transport, and areas with increased groundwater pumping show a greater susceptibility to erosion. Sediment collected in BSNE catchers was positively correlated with site gap size. Additionally, areas with larger gap sizes have a greater threshold shear velocity and soil stability, yet mass transport was greater at these sites than at sites with smaller gap sizes. Although modeling is complicated by spatial variation in multiple model parameters (e.g., gap size, threshold shear velocity in gaps), our results support the hypothesis that soils

  19. Crop production and economic loss due to wind erosion in hot arid ecosystem of India

    Science.gov (United States)

    Santra, Priyabrata; Moharana, P. C.; Kumar, Mahesh; Soni, M. L.; Pandey, C. B.; Chaudhari, S. K.; Sikka, A. K.

    2017-10-01

    Wind erosion is a severe land degradation process in hot arid western India and affects the agricultural production system. It affects crop yield directly by damaging the crops through abrasion, burial, dust deposition etc. and indirectly by reducing soil fertility. In this study, an attempt was made to quantify the indirect impact of wind erosion process on crop production loss and associated economic loss in hot arid ecosystem of India. It has been observed that soil loss due to wind erosion varies from minimum 1.3 t ha-1 to maximum 83.3 t ha-1 as per the severity. Yield loss due to wind erosion was found maximum for groundnut (Arachis hypogea) (5-331 kg ha-1 yr-1), whereas minimum for moth bean (Vigna aconitifolia) (1-93 kg ha-1 yr-1). For pearl millet (Pennisetum glaucum), which covers a major portion of arable lands in western Rajasthan, the yield loss was found 3-195 kg ha-1 yr-1. Economic loss was found higher for groundnut and clusterbean (Cyamopsis tetragonoloba) than rest crops, which are about

  20. Experience in the application of erosion-corrosion prediction programs

    International Nuclear Information System (INIS)

    Castiella Villacampa, E.; Cacho Cordero, L.; Pascual Velazquez, A.; Casar Asuar, M.

    1994-01-01

    Recently the results of the Nuclear Regulatory Commission's follow-on programme relating to the application of erosion-corrosion supervision and control programs were published. The main problems encountered in their practical application are highlighted, namely those associated with prediction, calculation of minimum thickness acceptable by code, results analyses of the thicknesses measured using ultrasound technology, cases of incorrect substitution, etc. A number of power plants in Spain are currently using a computerised prediction and monitoring program for the erosion-corrosion phenomenon. The experience gained in the application of this program has been such that it has led to a number or benefits: an improvement in the application of the program, proof of its suitability to real situation, the establishment of a series of criteria relative to the inclusion or exclusion of consideration during data input, the monitoring of the phenomenon, selection of elements for inspection, etc. The report describes these areas, using typical examples as illustrations. (Author)

  1. The National Wind Erosion Research Network: Building a standardized long-term data resource for aeolian research, modeling and land management

    Science.gov (United States)

    Webb, Nicholas P.; Herrick, Jeffrey E.; Van Zee, Justin W; Courtright, Ericha M; Hugenholtz, Ted M; Zobeck, Ted M; Okin, Gregory S.; Barchyn, Thomas E; Billings, Benjamin J; Boyd, Robert A.; Clingan, Scott D; Cooper, Brad F; Duniway, Michael C.; Derner, Justin D.; Fox, Fred A; Havstad, Kris M.; Heilman, Philip; LaPlante, Valerie; Ludwig, Noel A; Metz, Loretta J; Nearing, Mark A; Norfleet, M Lee; Pierson, Frederick B; Sanderson, Matt A; Sharrat, Brenton S; Steiner, Jean L; Tatarko, John; Tedela, Negussie H; Todelo, David; Unnasch, Robert S; Van Pelt, R Scott; Wagner, Larry

    2016-01-01

    The National Wind Erosion Research Network was established in 2014 as a collaborative effort led by the United States Department of Agriculture’s Agricultural Research Service and Natural Resources Conservation Service, and the United States Department of the Interior’s Bureau of Land Management, to address the need for a long-term research program to meet critical challenges in wind erosion research and management in the United States. The Network has three aims: (1) provide data to support understanding of basic aeolian processes across land use types, land cover types, and management practices, (2) support development and application of models to assess wind erosion and dust emission and their impacts on human and environmental systems, and (3) encourage collaboration among the aeolian research community and resource managers for the transfer of wind erosion technologies. The Network currently consists of thirteen intensively instrumented sites providing measurements of aeolian sediment transport rates, meteorological conditions, and soil and vegetation properties that influence wind erosion. Network sites are located across rangelands, croplands, and deserts of the western US. In support of Network activities, http://winderosionnetwork.org was developed as a portal for information about the Network, providing site descriptions, measurement protocols, and data visualization tools to facilitate collaboration with scientists and managers interested in the Network and accessing Network products. The Network provides a mechanism for engaging national and international partners in a wind erosion research program that addresses the need for improved understanding and prediction of aeolian processes across complex and diverse land use types and management practices.

  2. Wind erosion of waste impoundments in arid climates and mitigation of dust pollution.

    Science.gov (United States)

    Blight, G E

    2008-12-01

    Wind can erode and disperse fine-grained material from an impoundment of mining, industrial or municipal waste that stands above the level of its surroundings. Such dust dispersion can be a serious nuisance as well as a health hazard to inhabitants and animals in nearby settlements. It can also degrade crops, making them less marketable, and pollute soil, surface water and ground water. Wind can seasonally erode waste impoundments in all types of climate, but the erosion intensifies and persists for more of each year as regional aridity increases. As clouds of dust are often observed billowing across the top surfaces of waste impoundments in dry windy weather, there is a common misconception that dust arises from erosion of the top surface of an impoundment, resulting in much effort and money being misspent on top treatments when in fact the sloped sides of the impoundments are the true source of blown dust. This paper offers a brief review of general waste impoundment wind erosion issues and then focuses in more detail on the mechanics of how wind erodes surfaces of waste impoundments. Recommendations are offered for mitigating the effects of wind-eroded dust.

  3. Forest soil erosion prediction as influenced by wildfire and roads

    Science.gov (United States)

    Cao, L.; Brooks, E. S.; Elliot, W.

    2017-12-01

    Following a wildfire, the risk of erosion is greatly increased. Forest road networks may change the underlying topography and alter natural flow paths. Flow accumulation and energy can be redistributed by roads and alter soil erosion processes. A LiDAR (Light Detection and Ranging) DEM makes it possible to quantify road topography, and estimate how roads influence surface runoff and sediment transport in a fire-disturbed watershed. With GIS technology and a soil erosion model, this study was carried out to evaluate the effect of roads on erosion and sediment yield following the Emerald Fire southwest of Lake Tahoe. The GeoWEPP model was used to estimate onsite erosion and offsite sediment delivery from each hillslope polygon and channel segment before and after fire disturbance in part of the burned area. The GeoWEPP flow path method was used to estimate the post-fire erosion rate of each GIS pixel. A 2-m resolution LiDAR DEM was used as the terrain layer. The Emerald Fire greatly increased onsite soil loss and sediment yields within the fire boundary. Following the fire, 78.71% of the burned area had predicted sediment yields greater than 4 Mg/ha/yr, compared to the preburn condition when 65.3% of the study area was estimated to generate a sediment yield less than 0.25 Mg/ha/yr. Roads had a remarkable influence on the flow path simulation and sub-catchments delineation, affecting sediment transport process spatially. Road segments acted as barriers that intercepted overland runoff and reduced downslope flow energy accumulation, therefore reducing onsite soil loss downslope of the road. Roads also changed the boundary of sub-catchment and defined new hydrological units. Road segments can transport sediment from one sub-catchment to another. This in turn leads to the redistribution of sediment and alters sediment yield for some sub-catchments. Culverts and road drain systems are of vital importance in rerouting runoff and sediment. Conservation structures can be

  4. Environmental risks associated to wind erosion in a metal mining area from SE Spain

    International Nuclear Information System (INIS)

    Garcia Fernandez, G.; Romero Diaz, A.

    2009-01-01

    Soils and mining wastes from the Mediterranean mining area placed in the Sierra Minera Mountains are highly enriched in heavy metals such as lead and zinc, but also other metals such as cadmium and arsenic. Wind erosion in this area could be considered extremely high and hazards associated to this eroded sediments seems to be high because the huge amount of metals present in this wastes. Therefore, combination of high erosion rates and high metal concentration in this mining waste, make those environmental risks can be considered high for the surrounding ecosystems, but also for public health of the nearby villages and towns. In order, to study these wind erosion processes over these mining materials, some experiments for the evaluation of the transportation of soil particles were carried out. Erosion rates in this realm is particularly important during spring months, when increased activity of the eastern winds brings intense soil dragging, with strong effects on the metals dispersion, including the massive removal of sediments. (Author) 16 refs.

  5. Environmental risks associated to wind erosion in a metal mining area from SE Spain

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Fernandez, G.; Romero Diaz, A.

    2009-07-01

    Soils and mining wastes from the Mediterranean mining area placed in the Sierra Minera Mountains are highly enriched in heavy metals such as lead and zinc, but also other metals such as cadmium and arsenic. Wind erosion in this area could be considered extremely high and hazards associated to this eroded sediments seems to be high because the huge amount of metals present in this wastes. Therefore, combination of high erosion rates and high metal concentration in this mining waste, make those environmental risks can be considered high for the surrounding ecosystems, but also for public health of the nearby villages and towns. In order, to study these wind erosion processes over these mining materials, some experiments for the evaluation of the transportation of soil particles were carried out. Erosion rates in this realm is particularly important during spring months, when increased activity of the eastern winds brings intense soil dragging, with strong effects on the metals dispersion, including the massive removal of sediments. (Author) 16 refs.

  6. Wind Power Prediction using Ensembles

    DEFF Research Database (Denmark)

    Giebel, Gregor; Badger, Jake; Landberg, Lars

    2005-01-01

    offshore wind farm and the whole Jutland/Funen area. The utilities used these forecasts for maintenance planning, fuel consumption estimates and over-the-weekend trading on the Leipzig power exchange. Othernotable scientific results include the better accuracy of forecasts made up from a simple...... superposition of two NWP provider (in our case, DMI and DWD), an investigation of the merits of a parameterisation of the turbulent kinetic energy within thedelivered wind speed forecasts, and the finding that a “naïve” downscaling of each of the coarse ECMWF ensemble members with higher resolution HIRLAM did...

  7. Dust emission and soil loss due to anthropogenic activities by wind erosion simulations

    Science.gov (United States)

    Katra, Itzhak; Swet, Nitzan; Tanner, Smadar

    2017-04-01

    Wind erosion is major process of soil loss and air pollution by dust emission of clays, nutrients, and microorganisms. Many soils throughout the world are currently or potentially associated with dust emissions, especially in dryland zones. The research focuses on wind erosion in semi-arid soils (Northern Negev, Israel) that are subjected to increased human activities of urban development and agriculture. A boundary-layer wind tunnel has been used to study dust emission and soil loss by simulation and quantification of high-resolution wind processes. Field experiments were conducted in various surface types of dry loess soils. The experimental plots represent soils with long-term and short term influences of land uses such as agriculture (conventional and organic practices), grazing, and natural preserves. The wind tunnel was operated under various wind velocities that are above the threshold velocity of aeolian erosion. Total soil sediment and particulate matter (PM) fluxes were calculated. Topsoil samples from the experimental plots were analysed in the laboratory for physical and chemical characteristics including aggregation, organic matter, and high-resolution particle size distribution. The results showed variations in dust emission in response to surface types and winds to provide quantitative estimates of soil loss over time. Substantial loss of particulate matter that is < 10 micrometer in diameter, including clays and nutrients, was recorded in most experimental conditions. Integrative analyses of the topsoil properties and dust experiment highlight the significant implications for soil nutrient resources and management strategies as well as for PM loading to the atmosphere and air pollution.

  8. Short-term wind power prediction

    DEFF Research Database (Denmark)

    Joensen, Alfred K.

    2003-01-01

    , and to implement these models and methods in an on-line software application. The economical value of having predictions available is also briefly considered. The summary report outlines the background and motivation for developing wind power prediction models. The meteorological theory which is relevant......The present thesis consists of 10 research papers published during the period 1997-2002 together with a summary report. The objective of the work described in the thesis is to develop models and methods for calculation of high accuracy predictions of wind power generated electricity...

  9. A universal meteorological method to identify potential risk of wind erosion on heavy-textured soils

    Directory of Open Access Journals (Sweden)

    Středová Hana

    2015-06-01

    Full Text Available The climate of Central Europe, mainly winter seasons with no snow cover at lower altitudes and a spring drought as well, might cause erosion events on heavy-textured soils. The aim of this paper is to define a universal method to identify the potential risk of wind erosion on heavy-textured soils. The categorization of potential wind erosion risk due to meteorological conditions is based on: (i an evaluation of the number of freeze-thaw episodes forming bare soil surfaces during the cold period of year; and (ii, an evaluation of the number of days with wet soil surfaces during the cold period of year. In the period 2001–2012 (from November to March, episodes with temperature changes from positive to negative and vice versa (thaw-freeze and freeze-thaw cycles and the effects of wet soil surfaces in connection with aggregate disintegration, are identified. The data are spatially interpolated by GIS tools for areas in the Czech Republic with heavy-textured soils. Blending critical categories is used to locate potential risks. The level of risk is divided into six classes. Those areas identified as potentially most vulnerable are the same localities where the highest number of erosive episodes on heavy-textured soils was documented.

  10. Wind-Driven Erosion and Exposure Potential at Mars 2020 Rover Candidate-Landing Sites

    Science.gov (United States)

    Chojnacki, Matthew; Banks, Maria; Urso, Anna

    2018-01-01

    Aeolian processes have likely been the predominant geomorphic agent for most of Mars’ history and have the potential to produce relatively young exposure ages for geologic units. Thus, identifying local evidence for aeolian erosion is highly relevant to the selection of landing sites for future missions, such as the Mars 2020 Rover mission that aims to explore astrobiologically relevant ancient environments. Here we investigate wind-driven activity at eight Mars 2020 candidate-landing sites to constrain erosion potential at these locations. To demonstrate our methods, we found that contemporary dune-derived abrasion rates were in agreement with rover-derived exhumation rates at Gale crater and could be employed elsewhere. The Holden crater candidate site was interpreted to have low contemporary erosion rates, based on the presence of a thick sand coverage of static ripples. Active ripples at the Eberswalde and southwest Melas sites may account for local erosion and the dearth of small craters. Moderate-flux regional dunes near Mawrth Vallis were deemed unrepresentative of the candidate site, which is interpreted to currently be experiencing low levels of erosion. The Nili Fossae site displayed the most unambiguous evidence for local sand transport and erosion, likely yielding relatively young exposure ages. The downselected Jezero crater and northeast Syrtis sites had high-flux neighboring dunes and exhibited substantial evidence for sediment pathways across their ellipses. Both sites had relatively high estimated abrasion rates, which would yield young exposure ages. The downselected Columbia Hills site lacked evidence for sand movement, and contemporary local erosion rates are estimated to be relatively low. PMID:29568719

  11. Wind-Driven Erosion and Exposure Potential at Mars 2020 Rover Candidate-Landing Sites

    Science.gov (United States)

    Chojnacki, Matthew; Banks, Maria; Urso, Anna

    2018-02-01

    Aeolian processes have likely been the predominant geomorphic agent for most of Mars' history and have the potential to produce relatively young exposure ages for geologic units. Thus, identifying local evidence for aeolian erosion is highly relevant to the selection of landing sites for future missions, such as the Mars 2020 Rover mission that aims to explore astrobiologically relevant ancient environments. Here we investigate wind-driven activity at eight Mars 2020 candidate-landing sites to constrain erosion potential at these locations. To demonstrate our methods, we found that contemporary dune-derived abrasion rates were in agreement with rover-derived exhumation rates at Gale crater and could be employed elsewhere. The Holden crater candidate site was interpreted to have low contemporary erosion rates, based on the presence of a thick sand coverage of static ripples. Active ripples at the Eberswalde and southwest Melas sites may account for local erosion and the dearth of small craters. Moderate-flux regional dunes near Mawrth Vallis were deemed unrepresentative of the candidate site, which is interpreted to currently be experiencing low levels of erosion. The Nili Fossae site displayed the most unambiguous evidence for local sand transport and erosion, likely yielding relatively young exposure ages. The downselected Jezero crater and northeast Syrtis sites had high-flux neighboring dunes and exhibited substantial evidence for sediment pathways across their ellipses. Both sites had relatively high estimated abrasion rates, which would yield young exposure ages. The downselected Columbia Hills site lacked evidence for sand movement, and contemporary local erosion rates are estimated to be relatively low.

  12. Neural Network Classifiers for Local Wind Prediction.

    Science.gov (United States)

    Kretzschmar, Ralf; Eckert, Pierre; Cattani, Daniel; Eggimann, Fritz

    2004-05-01

    This paper evaluates the quality of neural network classifiers for wind speed and wind gust prediction with prediction lead times between +1 and +24 h. The predictions were realized based on local time series and model data. The selection of appropriate input features was initiated by time series analysis and completed by empirical comparison of neural network classifiers trained on several choices of input features. The selected input features involved day time, yearday, features from a single wind observation device at the site of interest, and features derived from model data. The quality of the resulting classifiers was benchmarked against persistence for two different sites in Switzerland. The neural network classifiers exhibited superior quality when compared with persistence judged on a specific performance measure, hit and false-alarm rates.

  13. Assessment and prediction of wind turbine noise

    International Nuclear Information System (INIS)

    Lowson, M.V.

    1993-01-01

    The significance of basic aerodynamic noise sources for wind turbine noise are assessed, using information on the aero-acoustic mechanisms of other rotors, which have been studied in depth for many years. From the analysis, areas of potential improvement in wind turbine noise prediction are defined. Suggestions are made for approaches to wind turbine noise control which separate the noise problems at cut-in from those at rated power. Some of these offer the possibility of noise reduction without unfavourable effects on performance. Based on this analysis, a new model for prediction of wind turbine noise is presented and comparisons made between prediction and experiment. The model is based on well established aeroacoustic theory and published laboratory data for the two principal sources, inflow turbulence and boundary layer trailing edge interaction. The new method gives good agreement with experiment with the case studied so far. Parametric trends and sensitivities for the model are presented. Comparisons with previous prediction methods are also given. A consequence of the new model is to put more emphasis on boundary layer trailing edge interaction as a noise source. There are prospects for reducing noise from this source detail changes to the wind turbine design. (author)

  14. Climatological changing effects on wind, precipitation and erosion: Large, meso and small scale analysis

    International Nuclear Information System (INIS)

    Aslan, Z.

    2004-01-01

    The Fourier transformation analysis for monthly average values of meteorological parameters has been considered, and amplitudes, phase angles have been calculated by using ground measurements in Turkey. The first order harmonics of meteorological parameters show large scale effects, while higher order harmonics show the effects of small scale fluctuations. The variations of first through sixth order harmonic amplitudes and phases provide a useful means of understanding the large and local scale effects on meteorological parameters. The phase angle can be used to determine the time of year the maximum or minimum of a given harmonic occurs. The analysis helps us to distinguish different pressure, relative humidity, temperature, precipitation and wind speed regimes and transition regions. Local and large scale phenomenon and some unusual seasonal patterns are also defined near Keban Dam and the irrigation area. Analysis of precipitation based on long term data shows that semi-annual fluctuations are predominant in the study area. Similarly, pressure variations are mostly influenced by semi-annual fluctuations. Temperature and humidity variations are mostly influenced by meso and micro scale fluctuations. Many large and meso scale climate change simulations for the 21st century are based on concentration of green house gases. A better understanding of these effects on soil erosion is necessary to determine social, economic and other impacts of erosion. The second part of this study covers the time series analysis of precipitation, rainfall erosivity and wind erosion at the Marmara Region. Rainfall and runoff erosivity factors are defined by considering the results of field measurements at 10 stations. Climatological changing effects on rainfall erosion have been determined by monitoring meteorological variables. In the previous studies, Fournier Index is defined to estimate the rainfall erosivity for the study area. The Fournier Index or in other words a climatic index

  15. Load prediction of stall regulated wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Bjoerck, A.; Dahlberg, J.Aa. [Aeronautical Research Inst. of Sweden, Bromma (Sweden); Carlen, I. [Chalmers Univ. of Technology, Goeteborg (Sweden). Div. of Marine Structural Engineering; Ganander, H. [Teknikgruppen AB, Sollentua (Sweden)

    1996-12-01

    Measurements of blade loads on a turbine situated in a small wind farm shows that the highest blade loads occur during operation close to the peak power i.e. when the turbine operates in the stall region. In this study the extensive experimental data base has been utilised to compare loads in selected campaigns with corresponding load predictions. The predictions are based on time domain simulations of the wind turbine structure, performed by the aeroelastic code VIDYN. In the calculations a model were adopted in order to include the effects of dynamic stall. This paper describes the work carried out so far within the project and key results. 5 refs, 10 figs

  16. Sonic anemometry and sediment traps to evaluate the effectiveness of windbreaks in preventing wind erosion

    Directory of Open Access Journals (Sweden)

    Alejandro López

    Full Text Available ABSTRACT The present work analyzes the effectiveness of windbreaks against wind erosion through the study of streamline patterns and turbulent flow by means of sonic anemometry and sediment traps. To this end, windbreaks composed of plastic meshes (7.5 m long and 0.7 m tall were used. Windbreaks are a good means to reduce wind erosion, as they produce a positive effect on the characteristics of air currents that are related to wind erosion processes. Due to their ease of installation and dismantling, plastic meshes are widely used in areas where they are not required permanently. In our study, the use of a mesh of 13 × 30 threads cm−2 and 39 % porosity resulted in an average reduction of 85 % in face velocity at a height of 0.4 m and a distance of 1 m from the windbreak. The turbulence intensity i increased behind the windbreak because the reduction of mean of air speed on the leeside caused by the flow of air through the windbreak. Fluctuation levels, however, remained stable. The mean values of turbulence kinetic energy k decreased by 65 % to 86 % at a distance of 1 m from the windbreak and at a height of 0.4 m. The windbreak reduces erosion and sediment transportation 2 m downwind (2.9 times the windbreak height. Nevertheless, sediment transportation was not reduced at a height of 1.0 m and the effect of the windbreak was not observed at a distance of 6 m downwind (8.6 m times the windbreak height.

  17. Relative contributions of wind and water erosion to total soil loss and its effect on soil properties in sloping croplands of the Chinese Loess Plateau.

    Science.gov (United States)

    Tuo, Dengfeng; Xu, Mingxiang; Gao, Guangyao

    2018-08-15

    Wind and water erosion are two dominant types of erosion that lead to soil and nutrient losses. Wind and water erosion may occur simultaneously to varying extents in semi-arid regions. The contributions of wind and water erosion to total erosion and their effects on soil quality, however, remains elusive. We used cesium-137 ( 137 Cs) inventories to estimate the total soil erosion and used the Revised Universal Soil Loss Equation (RUSLE) to quantify water erosion in sloping croplands. Wind erosion was estimated from the subtraction of the two. We also used 137 Cs inventories to calculate total soil erosion and validate the relationships of the soil quality and erosion at different slope aspects and positions. The results showed that wind erosion (1460tkm -2 a -1 ) on northwest-facing slope was responsible for approximately 39.7% of the total soil loss, and water erosion (2216tkm -2 a -1 ) accounted for approximately 60.3%. The erosion rates were 58.8% higher on northwest- than on southeast-facing slopes. Northwest-facing slopes had lower soil organic carbon, total nitrogen, clay, and silt contents than southeast-facing slopes, and thus, the 137 Cs inventories were lower, and the total soil erosions were higher on the northwest-facing slopes. The variations in soil physicochemical properties were related to total soil erosion. The lowest 137 Cs inventories and nutrient contents were recorded at the upper positions on the northwest-facing slopes due to the successive occurrence of more severe wind and water erosion at the same site. The results indicated that wind and water could accelerate the spatial variability of erosion rate and soil properties and cause serious decreases in the nutrient contents in sloping fields. Our research could help researchers develop soil strategies to reduce soil erosion according to the dominant erosion type when it occurs in a hilly agricultural area. Copyright © 2018 Elsevier B.V. All rights reserved.

  18. Mapping wind erosion hazard in Australia using MODIS-derived ground cover, soil moisture and climate data

    International Nuclear Information System (INIS)

    Yang, X; Leys, J

    2014-01-01

    This paper describes spatial modeling methods to identify wind erosion hazard (WEH) areas across Australia using the recently available time-series products of satellite-derived ground cover, soil moisture and wind speed. We implemented the approach and data sets in a geographic information system to produce WEH maps for Australia at 500 m ground resolution on a monthly basis for the recent thirteen year period (2000–2012). These maps reveal the significant wind erosion hazard areas and their dynamic tendencies at paddock and regional scales. Dust measurements from the DustWatch network were used to validate the model and interpret the dust source areas. The modeled hazard areas and changes were compared with results from a rule-set approach and the Computational Environmental Management System (CEMSYS) model. The study demonstrates that the time series products of ground cover, soil moisture and wind speed can be jointly used to identify landscape erodibility and to map seasonal changes of wind erosion hazard across Australia. The time series wind erosion hazard maps provide detailed and useful information to assist in better targeting areas for investments and continuous monitoring, evaluation and reporting that will lead to reduced wind erosion and improved soil condition

  19. Predicting annoyance by wind turbine noise

    NARCIS (Netherlands)

    Janssen, S.A.; Vos, H.; Eisses, A.R.; Pedersen, E.

    2010-01-01

    While wind turbines have beneficial effects for the environment, they inevitably generate environmental noise. In order to protect residents against unacceptable levels of noise, exposure-response relationships are needed to predict the expected percentage of people annoyed or highly annoyed at a

  20. Predictability and Variability of Wave and Wind

    DEFF Research Database (Denmark)

    Chozas, Julia Fernandez; Kofoed, Jens Peter; Sørensen, Hans Christian

    This project covers two fields of study: a) Wave energy predictability and electricity markets. b) Variability of the power output of WECs in diversified systems : diversified renewable systems with wave and offshore wind production. See page 2-4 in the report for a executive summery....

  1. Evaluation of the RWEQ and SWEEP in simulating soil and PM10 loss from a portable wind tunnel

    Science.gov (United States)

    Wind erosion threatens sustainable agriculture and environmental quality in the Columbia Plateau region of the US Pacific Northwest. Wind erosion models such as Wind Erosion Prediction System (WEPS) and the Revised Wind Erosion Equation (RWEQ) have been developed as tools for identifying practices t...

  2. Wind Erosion Caused by Land Use Changes Significantly Reduces Ecosystem Carbon Storage and Carbon Sequestration Potentials in Grassland

    Science.gov (United States)

    Li, P.; Chi, Y. G.; Wang, J.; Liu, L.

    2017-12-01

    Wind erosion exerts a fundamental influence on the biotic and abiotic processes associated with ecosystem carbon (C) cycle. However, how wind erosion under different land use scenarios will affect ecosystem C balance and its capacity for future C sequestration are poorly quantified. Here, we established an experiment in a temperate steppe in Inner Mongolia, and simulated different intensity of land uses: control, 50% of aboveground vegetation removal (50R), 100% vegetation removal (100R) and tillage (TI). We monitored lateral and vertical carbon flux components and soil characteristics from 2013 to 2016. Our study reveals three key findings relating to the driving factors, the magnitude and consequence of wind erosion on ecosystem C balance: (1) Frequency of heavy wind exerts a fundamental control over the severity of soil erosion, and its interaction with precipitation and vegetation characteristics explained 69% variation in erosion intensity. (2) With increases in land use intensity, the lateral C flux induced by wind erosion increased rapidly, equivalent to 33%, 86%, 111% and 183% of the net ecosystem exchange of the control site under control, 50R, 100R and TI sites, respectively. (3) After three years' treatment, erosion induced decrease in fine fractions led to 31%, 43%, 85% of permanent loss of C sequestration potential in the surface 5cm soil for 50R, 100R and TI sites. Overall, our study demonstrates that lateral C flux associated with wind erosion is too large to be ignored. The loss of C-enriched fine particles not only reduces current ecosystem C content, but also results in irreversible loss of future soil C sequestration potential. The dynamic soil characteristics need be considered when projecting future ecosystem C balance in aeolian landscape. We also propose that to maintain the sustainability of grassland ecosystems, land managers should focus on implementing appropriate land use rather than rely on subsequent managements on degraded soils.

  3. Soil drying and wind erosion as affected by different types of shelterbelts planted in the desert region of western Rajasthan, India

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, J.P.; Rao, G.G.S.N.; Gupta, G.N.; Rao, B.V.R.

    1983-03-01

    Studies on the effects of 8-year-old shelterbelt plantations indicate a general reduction in wind velocity, wind erosion and evaporative loss of moisture from fields protected with Prosopis juliflora, Cassia siamea and Acacia tortilis. Cassia siamea shelterbelts are the most effective in checking wind erosion and delaying drying of the soil. (Refs. 13).

  4. Soil wind erosion in ecological olive trees in the Tabernas desert (southeastern Spain): a wind tunnel experiment

    Science.gov (United States)

    Asensio, Carlos; Lozano, Francisco Javier; Gallardo, Pedro; Giménez, Antonio

    2016-08-01

    Wind erosion is a key component of the soil degradation processes. The purpose of this study is to find out the influence of material loss from wind on soil properties for different soil types and changes in soil properties in olive groves when they are tilled. The study area is located in the north of the Tabernas Desert, in the province of Almería, southeastern Spain. It is one of the driest areas in Europe, with a semiarid thermo-Mediterranean type of climate. We used a new wind tunnel model over three different soil types (olive-cropped Calcisol, Cambisol and Luvisol) and studied micro-plot losses and deposits detected by an integrated laser scanner. We also studied the image processing possibilities for examining the particles attached to collector plates located at the end of the tunnel to determine their characteristics and whether they were applicable to the setup. Samples collected in the traps at the end of the tunnel were analyzed. We paid special attention to the influence of organic carbon, carbonate and clay contents because of their special impact on soil crusting and the wind-erodible fraction. A principal components analysis (PCA) was carried out to find any relations on generated dust properties and the intensity and behavior of those relationships. Component 1 separated data with high N and OC contents from samples high in fine silt, CO3= and available K content. Component 2 separated data with high coarse silt and clay contents from data with high fine sand content. Component 3 was an indicator of available P2O5 content. Analysis of variance (ANOVA) was carried out to analyze the effect of soil type and sampling height on different properties of trapped dust. Calculations based on tunnel data showed overestimation of erosion in soil types and calculation of the fraction of soil erodible by wind done by other authors for Spanish soils. As the highest loss was found in Cambisols, mainly due to the effect on soil crusting and the wind

  5. Development and validation of a method to estimate the potential wind erosion risk in Germany

    Science.gov (United States)

    Funk, Roger; Deumlich, Detlef; Völker, Lidia

    2017-04-01

    The introduction of the Cross Compliance (CC) regulations for soil protection resulted in the demand for the classification of the the wind erosion risk on agricultural areas in Germany nationwide. A spatial highly resolved method was needed based on uniform data sets and validation principles, which provides a fair and equivalent procedure for all affected farmers. A GIS-procedure was developed, which derives the site specific wind erosion risk from the main influencing factors: soil texture, wind velocity, wind direction and landscape structure following the German standard DIN 19706. The procedure enables different approaches in the Federal States and comparable classification results. Here, we present the approach of the Federal State of Brandenburg. In the first step a complete soil data map was composed in a grid size of 10 x 10 m. Data were taken from 1.) the Soil quality Appraisal (scale 1:10.000), 2.) the Medium-scale Soil Mapping (MMK, 1:25.000), 3.) extrapolating the MMK, 4.) new Soil quality Appraisal (new areas after coal-mining). Based on the texture and carbon content the wind erosion susceptibility was divided in 6 classes. This map was combined with data of the annual average wind velocity resulting in an increase of the risk classes for wind velocities > 5 ms-1 and a decrease for structure is regarded by allocating a height to each landscape element, corresponding to the described features in the digital "Biotope and Land Use Map". The "hill shade" procedure of ArcGIS was used to set virtual shadows behind the landscape elements for eight directions. The relative frequency of wind from each direction was used as a weighting factor and multiplied with the numerical values of the shadowed cells. Depending on the distance to the landscape element the shadowing effect was combined with the risk classes. The results show that the wind erosion risk is obviously reduced by integrating landscape structures into the risk assessment. After the renewed

  6. Long-term predictive capability of erosion models

    Science.gov (United States)

    Veerabhadra, P.; Buckley, D. H.

    1983-01-01

    A brief overview of long-term cavitation and liquid impingement erosion and modeling methods proposed by different investigators, including the curve-fit approach is presented. A table was prepared to highlight the number of variables necessary for each model in order to compute the erosion-versus-time curves. A power law relation based on the average erosion rate is suggested which may solve several modeling problems.

  7. Assessing and Predicting Erosion from Off Highway Vehicle Trails in Front-Range Rocky Mountain Watersheds.

    Science.gov (United States)

    Howard, M. J.; Silins, U.; Anderson, A.

    2016-12-01

    Off highway vehicle (OHV) trails have the potential to deliver sediment to sensitive headwater streams and increased OHV use is a growing watershed management concern in many Rocky Mountain regions. Predictive tools for estimating erosion and sediment inputs are needed to support assessment and management of erosion from OHV trail networks. The objective of this study was to a) assess erodibility (K factor) and total erosion from OHV trail networks in Rocky Mountain watersheds in south-west Alberta, Canada, and to b) evaluate the applicability of the Universal Soil Loss Equation (USLE) for predicting OHV trail erosion to support erosion management strategies. Measured erosion rates and erodibility (K) from rainfall simulation plots on OHV trails during the summers of 2014 and 2015 were compared to USLE predicted erosion from these same trails. Measured erodibility (K) from 23 rainfall simulation plots was highly variable (0.001-0.273 Mg*ha*hr/ha*MJ*mm) as was total seasonal erosion from 52 large trail sections (0.0595-43.3 Mg/ha) across trail segments of variable slope, stoniness, and trail use intensity. In particular, intensity of trail use had a large effect on both erodibility and total erosion that is not presently captured by erodibility indices (K) derived from soil characteristics. Results of this study suggest that while application of USLE for predicting erosion from OHV trail networks may be useful for initial coarse erosion assessment, a better understanding of the effect of factors such as road/trail use intensity on erodibility is needed to support use of USLE or associated erosion prediction tools for road/trail erosion management.

  8. Prediction of Soil Erosion Rates in Japan where Heavily Forested Landscape with Unstable Terrain

    Science.gov (United States)

    Nanko, K.; Oguro, M.; Miura, S.; Masaki, T.

    2016-12-01

    Soil is fundamental for plant growth, water conservation, and sustainable forest management. Multidisciplinary interest in the role of the soil in areas such as biodiversity, ecosystem services, land degradation, and water security has been growing (Miura et al., 2015). Forest is usually protective land use from soil erosion because vegetation buffers rainfall power and erosivity. However, some types of forest in Japan show high susceptibility to soil erosion due to little ground cover and steep slopes exceeding thirty degree, especially young Japanese cypress (Chamaecyparis obtusa) plantations (Miura et al., 2002). This is a critical issue for sustainable forest management because C. obtusaplantations account for 10% of the total forest coverage in Japan (Forestry Agency, 2009). Prediction of soil erosion rates on nationwide scale is necessary to make decision for future forest management plan. To predict and map soil erosion rates across Japan, we applied three soil erosion models, RUSLE (Revised Universal Soil Loss Equation, Wischmeier and Smith, 1978), PESERA (Pan-European Soil Erosion Risk Assessment, Kirkby et al., 2003), and RMMF (Revised Morgan-Morgan-Finney, Morgan, 2001). The grid scale is 1-km. RUSLE and PESERA are most widely used erosion models today. RMMF includes interactions between rainfall and vegetation, such as canopy interception and ratio of canopy drainage in throughfall. Evaporated rainwater by canopy interception, generally accounts for 15-20% in annual rainfall, does not contribute soil erosion. Whereas, larger raindrops generated by canopy drainage produced higher splash erosion rates than gross rainfall (Nanko et al., 2008). Therefore, rainfall redistribution process in canopy should be considered to predict soil erosion rates in forested landscape. We compared the results from three erosion models and analyze the importance of environmental factors for the prediction of soil erosion rates. This research was supported by the Environment

  9. Challenges in soil erosion research and prediction model development

    Science.gov (United States)

    Quantification of soil erosion has been traditionally considered as a surface hydrologic process with equations for soil detachment and sediment transport derived from the mechanics and hydraulics of the rainfall and surface flow. Under the current erosion modeling framework, the soil has a constant...

  10. Advanced experimental and numerical techniques for cavitation erosion prediction

    CERN Document Server

    Chahine, Georges; Franc, Jean-Pierre; Karimi, Ayat

    2014-01-01

    This book provides a comprehensive treatment of the cavitation erosion phenomenon and state-of-the-art research in the field. It is divided into two parts. Part 1 consists of seven chapters, offering a wide range of computational and experimental approaches to cavitation erosion. It includes a general introduction to cavitation and cavitation erosion, a detailed description of facilities and measurement techniques commonly used in cavitation erosion studies, an extensive presentation of various stages of cavitation damage (including incubation and mass loss), and insights into the contribution of computational methods to the analysis of both fluid and material behavior. The proposed approach is based on a detailed description of impact loads generated by collapsing cavitation bubbles and a physical analysis of the material response to these loads. Part 2 is devoted to a selection of nine papers presented at the International Workshop on Advanced Experimental and Numerical Techniques for Cavitation Erosion (Gr...

  11. Experimental study on influence of vegetation coverage on runoff in wind-water erosion crisscross region

    Science.gov (United States)

    Wang, Jinhua; Zhang, Ronggang; Sun, Juan

    2018-02-01

    Using artificial rainfall simulation method, 23 simulation experiments were carried out in water-wind erosion crisscross region in order to analyze the influence of vegetation coverage on runoff and sediment yield. The experimental plots are standard plots with a length of 20m, width of 5m and slope of 15 degrees. The simulation experiments were conducted in different vegetation coverage experimental plots based on three different rainfall intensities. According to the experimental observation data, the influence of vegetation coverage on runoff and infiltration was analyzed. Vegetation coverage has a significant impact on runoff, and the higher the vegetation coverage is, the smaller the runoff is. Under the condition of 0.6mm/min rainfall intensity, the runoff volume from the experimental plot with 18% vegetation coverage was 1.2 times of the runoff from the experimental with 30% vegetation coverage. What’s more, the difference of runoff is more obvious in higher rainfall intensity. If the rainfall intensity reaches 1.32mm/min, the runoff from the experimental plot with 11% vegetation coverage is about 2 times as large as the runoff from the experimental plot with 53%vegetation coverage. Under the condition of small rainfall intensity, the starting time of runoff in the experimental plot with higher vegetation coverage is later than that in the experimental plot with low vegetation coverage. However, under the condition of heavy rainfall intensity, there is no obvious difference in the beginning time of runoff. In addition, the higher the vegetation coverage is, the deeper the rainfall infiltration depth is.The results can provide reference for ecological construction carried out in wind erosion crisscross region with serious soil erosion.

  12. Model Predictive Control with Constraints of a Wind Turbine

    DEFF Research Database (Denmark)

    Henriksen, Lars Christian; Poulsen, Niels Kjølstad

    2007-01-01

    Model predictive control of wind turbines offer a more systematic approach of constructing controllers that handle constraints while focusing on the main control objective. In this article several controllers are designed for different wind conditions and appropriate switching conditions ensure a...... an efficient control of the wind turbine over the entire range of wind speeds. Both onshore and floating offshore wind turbines are tested with the controllers.......Model predictive control of wind turbines offer a more systematic approach of constructing controllers that handle constraints while focusing on the main control objective. In this article several controllers are designed for different wind conditions and appropriate switching conditions ensure...

  13. Predicting the temporal relationship between soil cesium-137 and erosion rate

    International Nuclear Information System (INIS)

    Kachanoski, R.G.; De Jong, E.

    1984-01-01

    A model was developed that predicts the amount of 137 Cs remaining in soil as a function of time and erosion rate. The model accounts for atmospheric deposition, radioactive decay, tillage dilution, and erosion transport of 137 Cs, as well as seasonal differences in 137 Cs deposition and erosion rates. The model was used to estimate minimum resolution of erosion estimates based on detection limits and accuracy of 137 Cs measurement by gamma spectroscopy, as a function of time and erosion rate. The analysis showed that under Saskatchewan conditions, changes in 137 Cs at a given site can be used to estimate erosion rates between 0.5 and 10 kg m -2 yr -1 with reasonable precision, provided the sampling interval is at least 15 yr. The relationship of fraction of 137 Cs lost vs. erosion as predicted by the model was compared with other methods being used. The model was used to estimate erosion from selected Saskatchewan soils where 137 Cs levels were measured in 1966 and again in 1981. Erosion rates calculated with the model varied from 1 kg m -2 yr -1 for a sandy loam soil in continuous forage to 19 kg m -2 yr -1 for a similar soil in a crop-fallow rotation. Erosion estimates using the model were higher than those calculated by assuming that soil loss was directly proportional to 137 Cs loss, especially when 137 Cs loss was high

  14. The wind power prediction research based on mind evolutionary algorithm

    Science.gov (United States)

    Zhuang, Ling; Zhao, Xinjian; Ji, Tianming; Miao, Jingwen; Cui, Haina

    2018-04-01

    When the wind power is connected to the power grid, its characteristics of fluctuation, intermittent and randomness will affect the stability of the power system. The wind power prediction can guarantee the power quality and reduce the operating cost of power system. There were some limitations in several traditional wind power prediction methods. On the basis, the wind power prediction method based on Mind Evolutionary Algorithm (MEA) is put forward and a prediction model is provided. The experimental results demonstrate that MEA performs efficiently in term of the wind power prediction. The MEA method has broad prospect of engineering application.

  15. Wind Power Plant Prediction by Using Neural Networks: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Z.; Gao, W.; Wan, Y. H.; Muljadi, E.

    2012-08-01

    This paper introduces a method of short-term wind power prediction for a wind power plant by training neural networks based on historical data of wind speed and wind direction. The model proposed is shown to achieve a high accuracy with respect to the measured data.

  16. Predicting soil erosion risk at the Alqueva dam watershed

    OpenAIRE

    Ferreira, Vera; Panagopoulos, Thomas

    2012-01-01

    Soil erosion is serious economic and environmental concern. Assessing soil erosion risk in the Alqueva dam watershed is urgently needed to conserve soil and water resources and prevent the accelerated dam siltation, taking into account the possible land-use changes, due to tourism development, intensification of irrigated farming and biomass production, as well as climate change. A comprehensive methodology that integrates Revised Universal Soil Loss Equation (RUSLE) model and Geographic Info...

  17. Wind speed prediction using statistical regression and neural network

    Indian Academy of Sciences (India)

    Prediction of wind speed in the atmospheric boundary layer is important for wind energy assess- ment,satellite launching and aviation,etc.There are a few techniques available for wind speed prediction,which require a minimum number of input parameters.Four different statistical techniques,viz.,curve fitting,Auto Regressive ...

  18. Dst Prediction Based on Solar Wind Parameters

    Directory of Open Access Journals (Sweden)

    Yoon-Kyung Park

    2009-12-01

    Full Text Available We reevaluate the Burton equation (Burton et al. 1975 of predicting Dst index using high quality hourly solar wind data supplied by the ACE satellite for the period from 1998 to 2006. Sixty magnetic storms with monotonously decreasing main phase are selected. In order to determine the injection term (Q and the decay time (tau of the equation, we examine the relationships between Dst* and VB_s, Delta Dst* and VB_s, and Delta Dst* and Dst* during the magnetic storms. For this analysis, we take into account one hour of the propagation time from the ACE satellite to the magnetopause, and a half hour of the response time of the magnetosphere/ring current to the solar wind forcing. The injection term is found to be Q({nT}/h=-3.56VB_s for VB_s>0.5mV/m and Q({nT}/h=0 for VB_s leq0.5mV/m. The tau (hour is estimated as 0.060 Dst* + 16.65 for Dst*>-175nT and 6.15 hours for Dst* leq -175nT. Based on these empirical relationships, we predict the 60 magnetic storms and find that the correlation coefficient between the observed and predicted Dst* is 0.88. To evaluate the performance of our prediction scheme, the 60 magnetic storms are predicted again using the models by Burton et al. (1975 and O'Brien & McPherron (2000a. The correlation coefficients thus obtained are 0.85, the same value for both of the two models. In this respect, our model is slightly improved over the other two models as far as the correlation coefficients is concerned. Particularly our model does a better job than the other two models in predicting intense magnetic storms (Dst* lesssim -200nT.

  19. Adapting the Water Erosion Prediction Project (WEPP) model for forest applications

    Science.gov (United States)

    Shuhui Dun; Joan Q. Wu; William J. Elliot; Peter R. Robichaud; Dennis C. Flanagan; James R. Frankenberger; Robert E. Brown; Arthur C. Xu

    2009-01-01

    There has been an increasing public concern over forest stream pollution by excessive sedimentation due to natural or human disturbances. Adequate erosion simulation tools are needed for sound management of forest resources. The Water Erosion Prediction Project (WEPP) watershed model has proved useful in forest applications where Hortonian flow is the major form of...

  20. The Rangeland Hydrology and Erosion Model: A dynamic approach for predicting soil loss on rangelands

    Science.gov (United States)

    In this study we present the improved Rangeland Hydrology and Erosion Model (RHEM V2.3), a process-based erosion prediction tool specific for rangeland application. The article provides the mathematical formulation of the model and parameter estimation equations. Model performance is assessed agains...

  1. The role of bathymetry, wave obliquity and coastal curvature in dune erosion prediction

    NARCIS (Netherlands)

    Den Heijer, C.

    2013-01-01

    This study aims at reducing uncertainty in dune erosion predictions, in particular at complex dune coasts, in order to improve the assessment method for dune safety against flooding. To that end, state-of-the-art process-based dune erosion models are employed to further investigate issues

  2. Comparison of WEPP and APEX runoff and erosion prediction at field scale in Goodwater Creek Experimental Watershed

    Science.gov (United States)

    The Water Erosion Prediction Project (WEPP) and the Agricultural Policy/Environmental eXtender (APEX) are process-based models that can predict spatial and temporal distributions of erosion for hillslopes and watersheds. This study applies the WEPP model to predict runoff and erosion for a 35-ha fie...

  3. Erosion Prediction Analysis and Landuse Planning in Gunggung Watershed, Bali, Indonesia

    Science.gov (United States)

    Trigunasih, N. M.; Kusmawati, T.; Yuli Lestari, N. W.

    2018-02-01

    The purpose of this research is to predict the erosion that occurs in Gunggung watershed and sustainable landuse management plan. This research used the USLE (Universal Soil Loss Equation) methodology. The method used observation / field survey and soil analysis at the Soil Laboratory of Faculty of Agriculture, Udayana University. This research is divided into 5 stages, (1) land unit determination, (2) Field observation and soil sampling, (3) Laboratory analysis and data collection, (4) Prediction of erosion using USLE (Universal Soil Loss Equation) method, (5) The permissible erosion determination (EDP) then (6) determines the level of erosion hazard based on the depth of the soil, as well as the soil conservation plan if the erosion is greater than the allowed erosion, and (7) determining landuse management plan for sustainable agriculture. Erosion which value is smaller than soil loss tolerance can be exploited in a sustainable manner, while erosion exceeds allowable erosion will be conservation measures. Conservation action is the improvement of vegetation and land management. Land management like improvements the terrace, addition of organic matter, increase plant density, planting ground cover and planting layered header system will increase the land capability classes. Land use recommended after management is mixed plantation high density with forest plants, mix plantation high density with patio bench construction, seasonal cultivation and perennial crops, cultivation of perennial crops and cultivation of seasonal crops.

  4. Using wind tunnels to predict bird mortality in wind farms: the case of griffon vultures.

    Science.gov (United States)

    de Lucas, Manuela; Ferrer, Miguel; Janss, Guyonne F E

    2012-01-01

    Wind farms have shown a spectacular growth during the last 15 years. Avian mortality through collision with moving rotor blades is well-known as one of the main adverse impacts of wind farms. In Spain, the griffon vulture incurs the highest mortality rates in wind farms. As far as we know, this study is the first attempt to predict flight trajectories of birds in order to foresee potentially dangerous areas for wind farm development. We analyse topography and wind flows in relation to flight paths of griffon vultures, using a scaled model of the wind farm area in an aerodynamic wind tunnel, and test the difference between the observed flight paths of griffon vultures and the predominant wind flows. Different wind currents for each wind direction in the aerodynamic model were observed. Simulations of wind flows in a wind tunnel were compared with observed flight paths of griffon vultures. No statistical differences were detected between the observed flight trajectories of griffon vultures and the wind passages observed in our wind tunnel model. A significant correlation was found between dead vultures predicted proportion of vultures crossing those cells according to the aerodynamic model. Griffon vulture flight routes matched the predominant wind flows in the area (i.e. they followed the routes where less flight effort was needed). We suggest using these kinds of simulations to predict flight paths over complex terrains can inform the location of wind turbines and thereby reduce soaring bird mortality.

  5. Using wind tunnels to predict bird mortality in wind farms: the case of griffon vultures.

    Directory of Open Access Journals (Sweden)

    Manuela de Lucas

    Full Text Available BACKGROUND: Wind farms have shown a spectacular growth during the last 15 years. Avian mortality through collision with moving rotor blades is well-known as one of the main adverse impacts of wind farms. In Spain, the griffon vulture incurs the highest mortality rates in wind farms. METHODOLOGY/PRINCIPAL FINDINGS: As far as we know, this study is the first attempt to predict flight trajectories of birds in order to foresee potentially dangerous areas for wind farm development. We analyse topography and wind flows in relation to flight paths of griffon vultures, using a scaled model of the wind farm area in an aerodynamic wind tunnel, and test the difference between the observed flight paths of griffon vultures and the predominant wind flows. Different wind currents for each wind direction in the aerodynamic model were observed. Simulations of wind flows in a wind tunnel were compared with observed flight paths of griffon vultures. No statistical differences were detected between the observed flight trajectories of griffon vultures and the wind passages observed in our wind tunnel model. A significant correlation was found between dead vultures predicted proportion of vultures crossing those cells according to the aerodynamic model. CONCLUSIONS: Griffon vulture flight routes matched the predominant wind flows in the area (i.e. they followed the routes where less flight effort was needed. We suggest using these kinds of simulations to predict flight paths over complex terrains can inform the location of wind turbines and thereby reduce soaring bird mortality.

  6. I Got Them Dust Bowl Blues: Wind Erosion in the Music of the Southern Great Plains

    Science.gov (United States)

    Lee, J. A.

    2017-12-01

    This paper deals with the role of wind erosion and blowing dust on the music of the Dust Bowl region, a portion of the southern Great Plains of the United States. A defining characteristic of the region is dust storms, and in the 1930s, severe dust storms created dramatic images that came to symbolize all of the economic, social and environmental hardships suffered by the people during the 1930s. The music of the time, by Woody Guthrie and others, suggested that the region was being destroyed, never to recover. The region was resilient, however, and in recent decades, dust has been depicted in songs either as an adversity to be endured or simply as a normal part of life in the area. It may be that blowing dust has become a defining characteristic of the region because of a somewhat warped sense of pride in living in an often-difficult environment.

  7. Drawing a representative sample from the NCSS soil database: Building blocks for the national wind erosion network

    Science.gov (United States)

    Developing national wind erosion models for the continental United States requires a comprehensive spatial representation of continuous soil particle size distributions (PSD) for model input. While the current coverage of soil survey is nearly complete, the most detailed particle size classes have c...

  8. Prediction method for cavitation erosion based on measurement of bubble collapse impact loads

    International Nuclear Information System (INIS)

    Hattori, S; Hirose, T; Sugiyama, K

    2009-01-01

    The prediction of cavitation erosion rates is important in order to evaluate the exact life of components. The measurement of impact loads in bubble collapses helps to predict the life under cavitation erosion. In this study, we carried out erosion tests and the measurements of impact loads in bubble collapses with a vibratory apparatus. We evaluated the incubation period based on a cumulative damage rule by measuring the impact loads of cavitation acting on the specimen surface and by using the 'constant impact load - number of impact loads curve' similar to the modified Miner's rule which is employed for fatigue life prediction. We found that the parameter Σ(F i α xn i ) (F i : impact load, n i : number of impacts and α: constant) is suitable for the evaluation of the erosion life. Moreover, we propose a new method that can predict the incubation period under various cavitation conditions.

  9. A model to predict the power output from wind farms

    Energy Technology Data Exchange (ETDEWEB)

    Landberg, L. [Riso National Lab., Roskilde (Denmark)

    1997-12-31

    This paper will describe a model that can predict the power output from wind farms. To give examples of input the model is applied to a wind farm in Texas. The predictions are generated from forecasts from the NGM model of NCEP. These predictions are made valid at individual sites (wind farms) by applying a matrix calculated by the sub-models of WASP (Wind Atlas Application and Analysis Program). The actual wind farm production is calculated using the Riso PARK model. Because of the preliminary nature of the results, they will not be given. However, similar results from Europe will be given.

  10. Comparison of 137Cs fallout redistribution analysis and conventional erosion-prediction models (WEPP, USLE)

    International Nuclear Information System (INIS)

    Sparovek, G.; Bacchi, O.O.S.; Ranieri, S.B.L.; Schnug, E.; De-Maria, I.C.

    2002-01-01

    Soil erosion is the most important component of the degradation of tropical agroecosystems. The rates of erosion should be considered in land evaluation and conservation planning assessment. The methods available for erosion prediction are not sufficiently well calibrated or validated for tropical soils, climates and crops. Thus, differences in estimated soil-erosion values may be expected, even if considering a single set of input data. Three methods for the estimation of soil erosion (USLE, WEPP, and 137 Cs) were applied to a watershed cultivated with sugarcane in southeastern Brazil. The absolute erosion-rate values and differences in the spatial distribution were evaluated. The overall results suggest important differences in the estimates obtained by the three methods. The differences occurred both in mean values and in geographic locations. The relative mean values for soil loss were USLE>> 137 Cs>WEPP and for standard deviations were USLE>WEPP> 137 Cs, indicating that USLE predicted the highest erosion values spread out over the widest range. The poor geographical coincidence of the results is evidence that values resulting from non-calibrated erosion methods should be considered only as qualitative indications. The method selection should consider overall site variability in relation to factors to which the methods are known to be sensitive. (author)

  11. Atomic Oxygen Erosion Yield Prediction for Spacecraft Polymers in Low Earth Orbit

    Science.gov (United States)

    Banks, Bruce A.; Backus, Jane A.; Manno, Michael V.; Waters, Deborah L.; Cameron, Kevin C.; deGroh, Kim K.

    2009-01-01

    The ability to predict the atomic oxygen erosion yield of polymers based on their chemistry and physical properties has been only partially successful because of a lack of reliable low Earth orbit (LEO) erosion yield data. Unfortunately, many of the early experiments did not utilize dehydrated mass loss measurements for erosion yield determination, and the resulting mass loss due to atomic oxygen exposure may have been compromised because samples were often not in consistent states of dehydration during the pre-flight and post-flight mass measurements. This is a particular problem for short duration mission exposures or low erosion yield materials. However, as a result of the retrieval of the Polymer Erosion and Contamination Experiment (PEACE) flown as part of the Materials International Space Station Experiment 2 (MISSE 2), the erosion yields of 38 polymers and pyrolytic graphite were accurately measured. The experiment was exposed to the LEO environment for 3.95 years from August 16, 2001 to July 30, 2005 and was successfully retrieved during a space walk on July 30, 2005 during Discovery s STS-114 Return to Flight mission. The 40 different materials tested (including Kapton H fluence witness samples) were selected specifically to represent a variety of polymers used in space as well as a wide variety of polymer chemical structures. The MISSE 2 PEACE Polymers experiment used carefully dehydrated mass measurements, as well as accurate density measurements to obtain accurate erosion yield data for high-fluence (8.43 1021 atoms/sq cm). The resulting data was used to develop an erosion yield predictive tool with a correlation coefficient of 0.895 and uncertainty of +/-6.3 10(exp -25)cu cm/atom. The predictive tool utilizes the chemical structures and physical properties of polymers to predict in-space atomic oxygen erosion yields. A predictive tool concept (September 2009 version) is presented which represents an improvement over an earlier (December 2008) version.

  12. Separation of dry and wet periods from regular weather station data for the analysis of wind erosion risk

    DEFF Research Database (Denmark)

    Naeini, Mohammadali Saremi; Fister, Wolfgang; Heckrath, Goswin Johann

    importance, soil moisture content is often ignored in the analysis of wind data for wind erosion studies. The main reason most probably being the lack of soil moisture sensors in conventional climate stations. Soil moisture at a given point in time is determined by rain (e.g. rainfall amount, duration......), climate (e.g. air temperature, solar radiation, evaporation) and soil (e.g. infiltration rate, adhesion). The purpose of this study is to overcome the lack of soil moisture data for wind erosion risk assessment by developing a method to estimate the soil wetness based on easy available weather data......, such as daily precipitation, hourly/sub hourly ambient air temperature and hourly/sub hourly relative humidity. This new method was used to identify periods of wet and dry soil moisture conditions of a time series from 20 weather stations in Denmark. The length of the time series varied between 8 to 37 years...

  13. Atomic Oxygen Erosion Yield Predictive Tool for Spacecraft Polymers in Low Earth Orbit

    Science.gov (United States)

    Bank, Bruce A.; de Groh, Kim K.; Backus, Jane A.

    2008-01-01

    A predictive tool was developed to estimate the low Earth orbit (LEO) atomic oxygen erosion yield of polymers based on the results of the Polymer Erosion and Contamination Experiment (PEACE) Polymers experiment flown as part of the Materials International Space Station Experiment 2 (MISSE 2). The MISSE 2 PEACE experiment accurately measured the erosion yield of a wide variety of polymers and pyrolytic graphite. The 40 different materials tested were selected specifically to represent a variety of polymers used in space as well as a wide variety of polymer chemical structures. The resulting erosion yield data was used to develop a predictive tool which utilizes chemical structure and physical properties of polymers that can be measured in ground laboratory testing to predict the in-space atomic oxygen erosion yield of a polymer. The properties include chemical structure, bonding information, density and ash content. The resulting predictive tool has a correlation coefficient of 0.914 when compared with actual MISSE 2 space data for 38 polymers and pyrolytic graphite. The intent of the predictive tool is to be able to make estimates of atomic oxygen erosion yields for new polymers without requiring expensive and time consumptive in-space testing.

  14. Development and Life Prediction of Erosion Resistant Turbine Low Conductivity Thermal Barrier Coatings

    Science.gov (United States)

    Zhu, Dongming; Miller, Robert A.; Kuczmarski, Maria A.

    2010-01-01

    Future rotorcraft propulsion systems are required to operate under highly-loaded conditions and in harsh sand erosion environments, thereby imposing significant material design and durability issues. The incorporation of advanced thermal barrier coatings (TBC) in high pressure turbine systems enables engine designs with higher inlet temperatures, thus improving the engine efficiency, power density and reliability. The impact and erosion resistance of turbine thermal barrier coating systems are crucial to the turbine coating technology application, because a robust turbine blade TBC system is a prerequisite for fully utilizing the potential coating technology benefit in the rotorcraft propulsion. This paper describes the turbine blade TBC development in addressing the coating impact and erosion resistance. Advanced thermal barrier coating systems with improved performance have also been validated in laboratory simulated engine erosion and/or thermal gradient environments. A preliminary life prediction modeling approach to emphasize the turbine blade coating erosion is also presented.

  15. Model Predictive Control of Wind Turbines

    DEFF Research Database (Denmark)

    Henriksen, Lars Christian

    Wind turbines play a major role in the transformation from a fossil fuel based energy production to a more sustainable production of energy. Total-cost-of-ownership is an important parameter when investors decide in which energy technology they should place their capital. Modern wind turbines...... the need for maintenance of the wind turbine. Either way, better total-cost-of-ownership for wind turbine operators can be achieved by improved control of the wind turbines. Wind turbine control can be improved in two ways, by improving the model on which the controller bases its design or by improving...

  16. Predicted erosion and sediment delivery of fallout plutonium

    International Nuclear Information System (INIS)

    Foster, G.R.; Hakonson, T.E.

    1984-01-01

    Plutonium (Pu) from fallout after atmospheric explosion of nuclear weapons in the 1950s and 1960s is being redistributed over the landscape by soil erosion and carried on sediment by streams to oceans. Erosion rates computed with the Universal Soil Loss Equation for about 200,000 sample points on nonfederal land across the US were used to estimate Pu removal rates by soil erosion by water, Pu delivery in several major rivers, and concentration of Pu on the transported sediment. Estimates of average annual Pu delivery on sediment ranged from 0.002% of the initial fallout Pu inventory for the Savannah River basin to 0.08% for the Mississippi River basin. If the deposition of Pu had been uniformly 37 Bq/m 2 , the estimated Pu activity on suspended sediment ranged from about 0.26 Bq/kg of sediment for the Savannah River basin to 0.52 Bq/kg for the Columbia and Rio Grande river basins. After 1000 yr, about 9 to 48% of the initial Pu inventory will remain in US soils that are eroding. Much of the Pu on eroded sediment will travel only a short distance from its origin before its host sediment particles are deposited and permanently located, at least for a few hundred years. As much as 90% of the initially deposited Pu will remain, redistributed over the landscape by erosion and deposition. Although the delivery rate of Pu by rivers will not decrease greatly in the next 100 yr, a significant decrease will likely occur by 1000 yr

  17. Prediction of long-term erosion from landfill covers in the southwest

    International Nuclear Information System (INIS)

    Anderson, C.E.; Stormont, J.C.

    1997-01-01

    Erosion is a primary stressor of landfill covers, especially for climates with high intensity storms and low native plant density. Rills and gullies formed by discrete events can damage barrier layers and induce failure. Geomorphologic, empirical and physical modeling procedures are available to provide estimates of surface erosion, but numerical modeling requires accurate representation of the severe rainfall events that generate erosion. The National Weather Service precipitation frequency data and estimates of 5, 10, 15, 30 and 60-minute intensity can be statistically combined in a numerical model to obtain long-term erosion estimates. Physically based numerical models using the KINEROS and AHYMO programs have been utilized to predict the erosion from a southwestern landfill or waste containment site with 0.03, 0.05 and 0.08 meter per meter surface slopes. Results of AHYMO modeling were within 15 percent of average annual values computed with the empirical Universal Soil Loss Equation. However, the estimation of rill and gully formation that primarily degrades cover systems requires quantifying single events. For Southwestern conditions, a single 10-year storm can produce erosion quantifies equal to three times the average annual erosion and a 100-year storm can produce five times the average annual erosion

  18. Numerical Investigation of Temperature Distribution in an Eroded Bend Pipe and Prediction of Erosion Reduced Thickness

    Science.gov (United States)

    Zhu, Hongjun; Feng, Guang; Wang, Qijun

    2014-01-01

    Accurate prediction of erosion thickness is essential for pipe engineering. The objective of the present paper is to study the temperature distribution in an eroded bend pipe and find a new method to predict the erosion reduced thickness. Computational fluid dynamic (CFD) simulations with FLUENT software are carried out to investigate the temperature field. And effects of oil inlet rate, oil inlet temperature, and erosion reduced thickness are examined. The presence of erosion pit brings about the obvious fluctuation of temperature drop along the extrados of bend. And the minimum temperature drop presents at the most severe erosion point. Small inlet temperature or large inlet velocity can lead to small temperature drop, while shallow erosion pit causes great temperature drop. The dimensionless minimum temperature drop is analyzed and the fitting formula is obtained. Using the formula we can calculate the erosion reduced thickness, which is only needed to monitor the outer surface temperature of bend pipe. This new method can provide useful guidance for pipeline monitoring and replacement. PMID:24719576

  19. Skill forecasting from ensemble predictions of wind power

    DEFF Research Database (Denmark)

    Pinson, Pierre; Nielsen, Henrik Aalborg; Madsen, Henrik

    2009-01-01

    Optimal management and trading of wind generation calls for the providing of uncertainty estimates along with the commonly provided short-term wind power point predictions. Alternative approaches for the use of probabilistic forecasting are introduced. More precisely, focus is given to prediction...... risk indices aiming to give a comprehensive signal on the expected level of forecast uncertainty. Ensemble predictions of wind generation are used as input. A proposal for the definition of prediction risk indices is given. Such skill forecasts are based on the spread of ensemble forecasts (i.e. a set...... of alternative scenarios for the coming period) for a single prediction horizon or over a took-ahead period. It is shown on the test case of a Danish offshore wind farm how these prediction risk indices may be related to several levels of forecast uncertainty (and potential energy imbalances). Wind power...

  20. Using Wind Tunnels to Predict Bird Mortality in Wind Farms: The Case of Griffon Vultures

    OpenAIRE

    de Lucas, Manuela; Ferrer, Miguel; Janss, Guyonne F. E.

    2012-01-01

    Background: Wind farms have shown a spectacular growth during the last 15 years. Avian mortality through collision with moving rotor blades is well-known as one of the main adverse impacts of wind farms. In Spain, the griffon vulture incurs the highest mortality rates in wind farms. Methodology/Principal Findings: As far as we know, this study is the first attempt to predict flight trajectories of birds in order to foresee potentially dangerous areas for wind farm development. We analyse topo...

  1. Chapter 4. Predicting post-fire erosion and sedimentation risk on a landscape scale

    Science.gov (United States)

    MacDonald, L.H.; Sampson, R.; Brady, D.; Juarros, L.; Martin, Deborah

    2000-01-01

    Historic fire suppression efforts have increased the likelihood of large wildfires in much of the western U.S. Post-fire soil erosion and sedimentation risks are important concerns to resource managers. In this paper we develop and apply procedures to predict post-fire erosion and sedimentation risks on a pixel-, catchment-, and landscape-scale in central and western Colorado.Our model for predicting post-fire surface erosion risk is conceptually similar to the Revised Universal Soil Loss Equation (RUSLE). One key addition is the incorporation of a hydrophobicity risk index (HY-RISK) based on vegetation type, predicted fire severity, and soil texture. Post-fire surface erosion risk was assessed for each 90-m pixel by combining HYRISK, slope, soil erodibility, and a factor representing the likely increase in soil wetness due to removal of the vegetation. Sedimentation risk was a simple function of stream gradient. Composite surface erosion and sedimentation risk indices were calculated and compared across the 72 catchments in the study area.When evaluated on a catchment scale, two-thirds of the catchments had relatively little post-fire erosion risk. Steeper catchments with higher fuel loadings typically had the highest post-fire surface erosion risk. These were generally located along the major north-south mountain chains and, to a lesser extent, in west-central Colorado. Sedimentation risks were usually highest in the eastern part of the study area where a higher proportion of streams had lower gradients. While data to validate the predicted erosion and sedimentation risks are lacking, the results appear reasonable and are consistent with our limited field observations. The models and analytic procedures can be readily adapted to other locations and should provide useful tools for planning and management at both the catchment and landscape scale.

  2. Integration of fluvial erosion factors for predicting landslides along meandering rivers

    Science.gov (United States)

    Chen, Yi-chin; Chang, Kang-tsung; Ho, Jui-yi

    2015-04-01

    River incision and lateral erosion are important geomorphologic processes in mountainous areas of Taiwan. During a typhoon or storm event, the increase of water discharge, flow velocity, and sediment discharge enhances the power of river erosion on channel bank. After the materials on toe of hillslope were removed by river erosion, landslides were triggered at outer meander bends. Although it has been long expected that river erosion can trigger landslide, studies quantifying the effects of river erosion on landslide and the application of river erosion index in landslide prediction are still overlooked. In this study, we investigated the effect of river erosion on landslide in a particular meanders landscape of the Jhoukou River, southern Taiwan. We developed a semi-automatic model to separate meandering lines into several reach segments based on the inflection points and to calculate river erosion indexes, e.g. sinuosity of meander, stream power, and stream order, for each reach segment. This model, then, built the spatial relationship between the reaches and its corresponding hillslopes, of which the toe was eroded by the reach. Based on the spatial relationship, we quantified the correlations between these indexes and landslides triggered by Typhoon Morakot in 2009 to examine the effects of river erosion on landslide. The correlated indexes were then used as landslide predictors in logistic regression model. Results of the study showed that there is no significant correlation between landslide density and meander sinuosity. This may be a result of wider channel dispersing the erosion at a meandering reach. On the other hand, landslide density at concave bank is significantly higher than that at convex bank in the downstream (stream order > 3), but that is almost the same in the upstream (stream order bank. In contrast, river sediment in the downstream is an erosion agent eroding the concave bank laterally, but also depositing on the concave side and protecting

  3. Contributions of solar-wind induced potential sputtering to the lunar surface erosion rate and it's exosphere

    Science.gov (United States)

    Alnussirat, S. T.; Barghouty, A. F.; Edmunson, J. E.; Sabra, M. S.; Rickman, D. L.

    2018-04-01

    Sputtering of lunar regolith by solar-wind protons and heavy ions with kinetic energies of about 1 keV/amu is an important erosive process that affects the lunar surface and exosphere. It plays an important role in changing the chemical composition and thickness of the surface layer, and in introducing material into the exosphere. Kinetic sputtering is well modeled and understood, but understanding of mechanisms of potential sputtering has lagged behind. In this study we differentiate the contributions of potential sputtering from the standard (kinetic) sputtering in changing the chemical composition and erosion rate of the lunar surface. Also we study the contribution of potential sputtering in developing the lunar exosphere. Our results show that potential sputtering enhances the total characteristic sputtering erosion rate by about 44%, and reduces sputtering time scales by the same amount. Potential sputtering also introduces more material into the lunar exosphere.

  4. A methodology for the prediction of offshore wind energy resources

    Energy Technology Data Exchange (ETDEWEB)

    Watson, S J; Watson, G M [Rutherford Appleton Lab., Oxfordshire (United Kingdom); Holt, R.J. [Univ. of East Anglia, Climatic Research Unit, Norwich (United Kingdom)] Barthelmie, R.J. [Risoe National Lab., Dept. of Wind Energy and Atmospheric Physics, Roskilde (Denmark); Zuylen, E.J. van [Ecofys Energy and Environment, Utrecht (Netherlands)] Cleijne, J.W. [Kema Sustainable, Arnhem (Netherlands)

    1999-03-01

    There are increasing constraints on the development of wind power on land. Recently, there has been a move to develop wind power offshore, though the amount of measured wind speed data at potential offshore wind farm sites is sparse. We present a novel methodology for the prediction of offshore wind power resources which is being applied to European Union waters. The first stage is to calculate the geostrophic wind from long-term pressure fields over the sea area of interest. Secondly, the geostrophic wind is transformed to the sea level using WA{sup s}P, taking account of near shore topography. Finally, these values are corrected for land/sea climatology (stability) effects using an analytical Coastal discontinuity Model (CDM). These values are further refined using high resolution offshore data at selected sites. The final values are validated against existing offshore datasets. Preliminary results are presented of the geostrophic wind speed validation in European Union waters. (au)

  5. Retrospection of recent 30-year changes in the process of soil wind erosion in the Luanhe River Source Area of North China using Cesium-137

    Energy Technology Data Exchange (ETDEWEB)

    Chen Zhifan [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, 19 Xin Jie Kou Wai St., Beijing 100875 (China) and College of Environment and Planning, Henan University, Kaifeng 475001 (China)], E-mail: chenzhf0604@163.com; Zhao Ye [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, 19 Xin Jie Kou Wai St., Beijing 100875 (China)], E-mail: zhaoye@bnu.edu.cn; Qiao Jiejuan [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, 19 Xin Jie Kou Wai St., Beijing 100875 (China); Zhang Qing [National Institute for Radiological Protection, Chinese Center for Disease Control and Protection, Beijing 100088 (China); Zhu Yuen [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, 19 Xin Jie Kou Wai St., Beijing 100875 (China); Xu Cuihua [National Institute for Radiological Protection, Chinese Center for Disease Control and Protection, Beijing 100088 (China)

    2009-10-15

    The Luanhe River Source Area belongs to typical semi-arid, agro-pastoral ecotone of North China. It is very important for the prevention and treatment of soil erosion in North China to analyze and evaluate quantitatively the recent 30-year changes in the process of soil wind erosion in this area. Based on long field observations, soil samples from different depths in a representative wind-deposited soil profile in the Luanhe River Source Area were collected. Then the {sup 137}Cs activity of soil samples from different depths in the soil profile was determined using a GEM series HPGe (high-purity germanium) coaxial detector system (ADCAM-100), and their soil properties, such as the soil particle fraction and so on, were analyzed. According to the detected {sup 137}Cs activity of different depths, a continuous time sequence of the wind-deposited soil profile in the study area was established. Furthermore, through assumption on a soil relative wind erosion intensity index (SWEI), recent 30-year changes in the process of soil wind erosion in the Luanhe River Source Area were retrospected . The analysis results revealed that weaker soil wind erosion occurred in the study area from the 1970s to the early 1980s and from the late 1980s to the mid to late 1990s. Conversely, intense periods of soil wind erosion occurred in the mid-1980s and from the late 1990s to 2002.

  6. Retrospection of recent 30-year changes in the process of soil wind erosion in the Luanhe River Source Area of North China using Cesium-137

    International Nuclear Information System (INIS)

    Chen Zhifan; Zhao Ye; Qiao Jiejuan; Zhang Qing; Zhu Yuen; Xu Cuihua

    2009-01-01

    The Luanhe River Source Area belongs to typical semi-arid, agro-pastoral ecotone of North China. It is very important for the prevention and treatment of soil erosion in North China to analyze and evaluate quantitatively the recent 30-year changes in the process of soil wind erosion in this area. Based on long field observations, soil samples from different depths in a representative wind-deposited soil profile in the Luanhe River Source Area were collected. Then the 137 Cs activity of soil samples from different depths in the soil profile was determined using a GEM series HPGe (high-purity germanium) coaxial detector system (ADCAM-100), and their soil properties, such as the soil particle fraction and so on, were analyzed. According to the detected 137 Cs activity of different depths, a continuous time sequence of the wind-deposited soil profile in the study area was established. Furthermore, through assumption on a soil relative wind erosion intensity index (SWEI), recent 30-year changes in the process of soil wind erosion in the Luanhe River Source Area were retrospected . The analysis results revealed that weaker soil wind erosion occurred in the study area from the 1970s to the early 1980s and from the late 1980s to the mid to late 1990s. Conversely, intense periods of soil wind erosion occurred in the mid-1980s and from the late 1990s to 2002.

  7. 7 CFR 610.12 - Equations for predicting soil loss due to water erosion.

    Science.gov (United States)

    2010-01-01

    .... (a) The equation for predicting soil loss due to erosion for both the USLE and the RUSLE is A = R × K... 22161.) (b) The factors in the USLE equation are: (1) A is the estimation of average annual soil loss in... 7 Agriculture 6 2010-01-01 2010-01-01 false Equations for predicting soil loss due to water...

  8. Wind Predictions Upstream Wind Turbines from a LiDAR Database

    Directory of Open Access Journals (Sweden)

    Soledad Le Clainche

    2018-03-01

    Full Text Available This article presents a new method to predict the wind velocity upstream a horizontal axis wind turbine from a set of light detection and ranging (LiDAR measurements. The method uses higher order dynamic mode decomposition (HODMD to construct a reduced order model (ROM that can be extrapolated in space. LiDAR measurements have been carried out upstream a wind turbine at six different planes perpendicular to the wind turbine axis. This new HODMD-based ROM predicts with high accuracy the wind velocity during a timespan of 24 h in a plane of measurements that is more than 225 m far away from the wind turbine. Moreover, the technique introduced is general and obtained with an almost negligible computational cost. This fact makes it possible to extend its application to both vertical axis wind turbines and real-time operation.

  9. Model predictive control for wind power gradients

    DEFF Research Database (Denmark)

    Hovgaard, Tobias Gybel; Boyd, Stephen; Jørgensen, John Bagterp

    2015-01-01

    We consider the operation of a wind turbine and a connected local battery or other electrical storage device, taking into account varying wind speed, with the goal of maximizing the total energy generated while respecting limits on the time derivative (gradient) of power delivered to the grid. We...... ranges. The system dynamics are quite non-linear, and the constraints and objectives are not convex functions of the control inputs, so the resulting optimal control problem is difficult to solve globally. In this paper, we show that by a novel change of variables, which focuses on power flows, we can...... wind data and modern wind forecasting methods. The simulation results using real wind data demonstrate the ability to reject the disturbances from fast changes in wind speed, ensuring certain power gradients, with an insignificant loss in energy production....

  10. Improved Wind Speed Prediction Using Empirical Mode Decomposition

    Directory of Open Access Journals (Sweden)

    ZHANG, Y.

    2018-05-01

    Full Text Available Wind power industry plays an important role in promoting the development of low-carbon economic and energy transformation in the world. However, the randomness and volatility of wind speed series restrict the healthy development of the wind power industry. Accurate wind speed prediction is the key to realize the stability of wind power integration and to guarantee the safe operation of the power system. In this paper, combined with the Empirical Mode Decomposition (EMD, the Radial Basis Function Neural Network (RBF and the Least Square Support Vector Machine (SVM, an improved wind speed prediction model based on Empirical Mode Decomposition (EMD-RBF-LS-SVM is proposed. The prediction result indicates that compared with the traditional prediction model (RBF, LS-SVM, the EMD-RBF-LS-SVM model can weaken the random fluctuation to a certain extent and improve the short-term accuracy of wind speed prediction significantly. In a word, this research will significantly reduce the impact of wind power instability on the power grid, ensure the power grid supply and demand balance, reduce the operating costs in the grid-connected systems, and enhance the market competitiveness of the wind power.

  11. Prediction models for wind speed at turbine locations in a wind farm

    DEFF Research Database (Denmark)

    Knudsen, Torben; Bak, Thomas; Soltani, Mohsen

    2011-01-01

    In wind farms, individual turbines disturb the wind field by generating wakes that influence other turbines in the farm. From a control point of view, there is an interest in dynamic optimization of the balance between fatigue and production, and an understanding of the relationship between turbines...... on standard turbine measurements such as rotor speed and power produced, an effective wind speed, which represents the wind field averaged over the rotor disc, is derived. The effective wind speed estimator is based on a continuous–discrete extended Kalman filter that takes advantage of nonlinear time varying...... on the result related to effective wind speed, it is possible to predict wind speeds at neighboring turbines, with a separation of over 700 m, up to 1 min ahead reducing the error by 30% compared with a persistence method. The methodological results are demonstrated on data from an off-shore wind farm...

  12. Assessment of wind erosion threat for soils in cadastral area of Hajske

    International Nuclear Information System (INIS)

    Muchova, Z.; Stredanska, A.

    2008-01-01

    This contribution illustrates the application of methods of erosion threat assessment in lan adaptation projects. Calculations of the soil erosion index of particular soil blocks are demonstrated for the cadastral area of Hajske. Two methods for assessment of erosion threat have been applied. First the assessment based on the ecological soil-quality units (ESQU) has been performed. Next, the Pasak method for a detailed analysis of the soil erosion threat was applied. Both of the mentioned approaches are recommended for the land adaption projects. Based on the results, the soil blocks have been ranked by their soil erosion threat. (authors)

  13. A GIS-model for predicting the impact of climate change on shore erosion in hydroelectric reservoirs

    International Nuclear Information System (INIS)

    Penner, L.A.; Zimmer, T.A.M.; St Laurent, M.

    2008-01-01

    Shoreline erosion affects inland lakes and hydroelectric reservoirs in several ways. This poster described a vector-based geographic information system (GIS) model designed to predict changes in shore zone geometry, top-of-bluff recession, and eroded sediment volumes. The model was designed for use in Manitoba Hydro's reservoirs in northern Manitoba, and simulated near-shore downcutting and bank recession caused by wind-generated waves. Parameters for the model included deep water wave energy, and water level fluctuations. Effective wave energy was seen as a function of the water level fluctuation range, wave conditions, and near-shore slope. The model was validated by field monitoring studies that included repeated shore zone transect surveys and sediment coring studies. Results of the study showed that the model provides a systematic method of predicting potential changes in erosion associated with climatic change. The volume and mass of eroded sediment predicted for the different modelling scenarios will be used as input data for future sedimentation models. tabs., figs

  14. On the Material Characterisation of Wind Turbine Blade Coatings: The Effect of Interphase Coating–Laminate Adhesion on Rain Erosion Performance

    Directory of Open Access Journals (Sweden)

    Enrique Cortés

    2017-09-01

    Full Text Available Rain erosion damage, caused by repeated droplet impact on wind turbine blades, is a major cause for concern, even more so at offshore locations with larger blades and higher tip speeds. Due to the negative economic influence of blade erosion, all wind turbine Original Equipment Manufacturers (OEMs are actively seeking solutions. In most cases, since the surface coating plays a decisive role in the blade manufacture and overall performance, it has been identified as an area where a solution may be obtained. In this research, two main coating technologies have been considered: In-mould coatings (Gel coating applied during moulding on the entire blade surface and the post-mould coatings specifically developed for Leading Edge Protection (LEP. The coating adhesion and erosion is affected by the shock waves created by the collapsing water droplets on impact. The stress waves are reflected and transmitted to the laminate substrate, so microstructural discontinuities in coating layers and interfaces play a key role on its degradation and may accelerate erosion by delamination. Analytical and numerical models are commonly used to relate lifetime prediction and to identify suitable coating and composite substrate combinations based on their potential stress reduction on the interface. Nevertheless, in order to use them, it is necessary to measure the contact adhesion resistance of the multi-layered system interfaces. The rain erosion performance is assessed using an accelerated testing technique, whereby the test material is repeatedly impacted at high speed with water droplets in a Whirling Arm Rain Erosion Rig (WARER. The materials, specifically the coating–laminate interphase region and acoustic properties, are further characterised by several laboratory tests, including Differential Scanning Calorimetry (DSC, pull-off testing, peeling–adhesion testing and nanoindentation testing. This body of work includes a number of case studies. The first case

  15. On the Material Characterisation of Wind Turbine Blade Coatings: The Effect of Interphase Coating–Laminate Adhesion on Rain Erosion Performance

    Science.gov (United States)

    Cortés, Enrique; Sánchez, Fernando; Madramany, Borja

    2017-01-01

    Rain erosion damage, caused by repeated droplet impact on wind turbine blades, is a major cause for concern, even more so at offshore locations with larger blades and higher tip speeds. Due to the negative economic influence of blade erosion, all wind turbine Original Equipment Manufacturers (OEMs) are actively seeking solutions. In most cases, since the surface coating plays a decisive role in the blade manufacture and overall performance, it has been identified as an area where a solution may be obtained. In this research, two main coating technologies have been considered: In-mould coatings (Gel coating) applied during moulding on the entire blade surface and the post-mould coatings specifically developed for Leading Edge Protection (LEP). The coating adhesion and erosion is affected by the shock waves created by the collapsing water droplets on impact. The stress waves are reflected and transmitted to the laminate substrate, so microstructural discontinuities in coating layers and interfaces play a key role on its degradation and may accelerate erosion by delamination. Analytical and numerical models are commonly used to relate lifetime prediction and to identify suitable coating and composite substrate combinations based on their potential stress reduction on the interface. Nevertheless, in order to use them, it is necessary to measure the contact adhesion resistance of the multi-layered system interfaces. The rain erosion performance is assessed using an accelerated testing technique, whereby the test material is repeatedly impacted at high speed with water droplets in a Whirling Arm Rain Erosion Rig (WARER). The materials, specifically the coating–laminate interphase region and acoustic properties, are further characterised by several laboratory tests, including Differential Scanning Calorimetry (DSC), pull-off testing, peeling–adhesion testing and nanoindentation testing. This body of work includes a number of case studies. The first case study compares

  16. On the Material Characterisation of Wind Turbine Blade Coatings: The Effect of Interphase Coating-Laminate Adhesion on Rain Erosion Performance.

    Science.gov (United States)

    Cortés, Enrique; Sánchez, Fernando; O'Carroll, Anthony; Madramany, Borja; Hardiman, Mark; Young, Trevor M

    2017-09-28

    Rain erosion damage, caused by repeated droplet impact on wind turbine blades, is a major cause for concern, even more so at offshore locations with larger blades and higher tip speeds. Due to the negative economic influence of blade erosion, all wind turbine Original Equipment Manufacturers (OEMs) are actively seeking solutions. In most cases, since the surface coating plays a decisive role in the blade manufacture and overall performance, it has been identified as an area where a solution may be obtained. In this research, two main coating technologies have been considered: In-mould coatings (Gel coating) applied during moulding on the entire blade surface and the post-mould coatings specifically developed for Leading Edge Protection (LEP). The coating adhesion and erosion is affected by the shock waves created by the collapsing water droplets on impact. The stress waves are reflected and transmitted to the laminate substrate, so microstructural discontinuities in coating layers and interfaces play a key role on its degradation and may accelerate erosion by delamination. Analytical and numerical models are commonly used to relate lifetime prediction and to identify suitable coating and composite substrate combinations based on their potential stress reduction on the interface. Nevertheless, in order to use them, it is necessary to measure the contact adhesion resistance of the multi-layered system interfaces. The rain erosion performance is assessed using an accelerated testing technique, whereby the test material is repeatedly impacted at high speed with water droplets in a Whirling Arm Rain Erosion Rig (WARER). The materials, specifically the coating-laminate interphase region and acoustic properties, are further characterised by several laboratory tests, including Differential Scanning Calorimetry (DSC), pull-off testing, peeling-adhesion testing and nanoindentation testing. This body of work includes a number of case studies. The first case study compares two

  17. DES Prediction of Cavitation Erosion and Its Validation for a Ship Scale Propeller

    Science.gov (United States)

    Ponkratov, Dmitriy, Dr

    2015-12-01

    Lloyd's Register Technical Investigation Department (LR TID) have developed numerical functions for the prediction of cavitation erosion aggressiveness within Computational Fluid Dynamics (CFD) simulations. These functions were previously validated for a model scale hydrofoil and ship scale rudder [1]. For the current study the functions were applied to a cargo ship's full scale propeller, on which the severe cavitation erosion was reported. The performed Detach Eddy Simulation (DES) required a fine computational mesh (approximately 22 million cells), together with a very small time step (2.0E-4 s). As the cavitation for this type of vessel is primarily caused by a highly non-uniform wake, the hull was also included in the simulation. The applied method under predicted the cavitation extent and did not fully resolve the tip vortex; however, the areas of cavitation collapse were captured successfully. Consequently, the developed functions showed a very good prediction of erosion areas, as confirmed by comparison with underwater propeller inspection results.

  18. Wind prediction in Malaysia using Mycielski-1 approach

    Science.gov (United States)

    Lee, S. W.; Kok, B. C.; Goh, K. C.; Goh, H. H.

    2012-11-01

    In this paper, the wind speed prediction in Kudat, Malaysia had been done by using Mycielski-1 approach. There is some improvement in obtaining the random number of Mycielski-1. The wind prediction is important to study a favorable site's wind potential. The prediction is based on 3 years history data provided by Meteorology Department of Malaysia and 1 year data as the reference to check the accuracy of this algorithm. The basic concept of this algorithm is to predict the next value by looking to history data. The result shows the prediction of Mycielski-1 algorithm is promising. The wind speed is predicted in order to obtain the mean power for energy planning.

  19. Wind power prediction based on genetic neural network

    Science.gov (United States)

    Zhang, Suhan

    2017-04-01

    The scale of grid connected wind farms keeps increasing. To ensure the stability of power system operation, make a reasonable scheduling scheme and improve the competitiveness of wind farm in the electricity generation market, it's important to accurately forecast the short-term wind power. To reduce the influence of the nonlinear relationship between the disturbance factor and the wind power, the improved prediction model based on genetic algorithm and neural network method is established. To overcome the shortcomings of long training time of BP neural network and easy to fall into local minimum and improve the accuracy of the neural network, genetic algorithm is adopted to optimize the parameters and topology of neural network. The historical data is used as input to predict short-term wind power. The effectiveness and feasibility of the method is verified by the actual data of a certain wind farm as an example.

  20. Predicting rainfall erosivity by momentum and kinetic energy in Mediterranean environment

    Science.gov (United States)

    Carollo, Francesco G.; Ferro, Vito; Serio, Maria A.

    2018-05-01

    Rainfall erosivity is an index that describes the power of rainfall to cause soil erosion and it is used around the world for assessing and predicting soil loss on agricultural lands. Erosivity can be represented in terms of both rainfall momentum and kinetic energy, both calculated per unit time and area. Contrasting results on the representativeness of these two variables are available: some authors stated that momentum and kinetic energy are practically interchangeable in soil loss estimation while other found that kinetic energy is the most suitable expression of rainfall erosivity. The direct and continuous measurements of momentum and kinetic energy by a disdrometer allow also to establish a relationship with rainfall intensity at the study site. At first in this paper a comparison between the momentum-rainfall intensity relationships measured at Palermo and El Teularet by an optical disdrometer is presented. For a fixed rainfall intensity the measurements showed that the rainfall momentum values measured at the two experimental sites are not coincident. However both datasets presented a threshold value of rainfall intensity over which the rainfall momentum assumes a quasi-constant value. Then the reliability of a theoretically deduced relationship, linking momentum, rainfall intensity and median volume diameter, is positively verified using measured raindrop size distributions. An analysis to assess which variable, momentum or kinetic energy per unit area and time, is the best predictor of erosivity in Italy and Spain was also carried out. This investigation highlighted that the rainfall kinetic energy per unit area and time can be substituted by rainfall momentum as index for estimating the rainfall erosivity, and this result does not depend on the site where precipitation occurs. Finally, rainfall intensity measurements and soil loss data collected from the bare plots equipped at Sparacia experimental area were used to verify the reliability of some

  1. Evaluation of the 137Cs technique for estimating wind erosion losses for some sandy Western Australian soils

    International Nuclear Information System (INIS)

    Harper, R.J.; Gilkes, R.J.

    1994-01-01

    The utility of the caesium-137 technique, for estimating the effects of wind erosion, was evaluated on the soils of a semi-arid agricultural area near Jerramungup, Western Australia. The past incidence of wind erosion was estimated from field observations of soil profile morphology and an existing remote sensing study. Erosion was limited to sandy surfaced soils (0-4% clay), with a highly significant difference (P 137 Cs values between eroded and non-eroded sandy soils, with mean values of 243±17 and 386±13 Bq m -2 respectively. Non-eroded soils, with larger clay contents, had a mean 137 Cs content of 421±26 Bq m -2 , however, due to considerable variation between replicate samples, this value was not significantly different from that of the non-eroded sands. Hence, although the technique discriminates between eroded and non-eroded areas, the large variation in 137 Cs values means that from 27 to 96 replicate samples are required to provide statistically valid estimates of 137 Cs loss. The occurrence of around 18% of the total 137 Cs between 10 and 20 cm depth in these soils, despite cultivation being confined to the surface 9 cm, suggests that leaching of 137 Cs occurs in the sandy soils, although there was no relationship between clay content and 137 Cs value for either eroded or non-eroded soils. In a multiple linear regression, organic carbon content and the mean grain size of the eroded soils explained 35% of the variation in 137 Cs content. This relationship suggests that both organic carbon and 137 Cs are removed by erosion, with erosion being more prevalent on soils with a finer sand fraction. Clay and silt contents do not vary with depth in the near-surface horizons of the eroded sandy soils, hence it is likely that wind erosion strips the entire surface horizon with its 137 Cs content, rather than selectively winnowing fine material. 71 refs., 6 tabs., 2 fig

  2. VT Predicted Mean Wind Speed - 70 meter height

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) Wind speed predictions at 70m are generated by a numerical model that simulates weather conditions over a 15-year period, taking into account...

  3. VT Predicted Mean Wind Power - 50 meter height

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) Wind power predictions at 50m are generated by a numerical model that simulates weather conditions over a 15-year period, taking into account...

  4. VT Predicted Mean Wind Speed - 30 meter height

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) Wind speed predictions at 30m are generated by a numerical model that simulates weather conditions over a 15-year period, taking into account...

  5. How to diagnose rheumatoid arthritis early: a prediction model for persistent (erosive) arthritis

    NARCIS (Netherlands)

    Visser, Henk; le Cessie, Saskia; Vos, Koen; Breedveld, Ferdinand C.; Hazes, Johanna M. W.

    2002-01-01

    To develop a clinical model for the prediction, at the first visit, of 3 forms of arthritis outcome: self-limiting, persistent nonerosive, and persistent erosive arthritis. A standardized diagnostic evaluation was performed on 524 consecutive, newly referred patients with early arthritis.

  6. WPPT, a tool for on-line wind power prediction

    Energy Technology Data Exchange (ETDEWEB)

    Skov Nielsen, T. [Dept. of Mathematical Modelling (IMM-DTU), Kgs. Lyngby (Denmark); Madsen, H. [Dept. of Mathematical Modelling (IMM-DTU) Kgs. Lyngby (Denmark); Toefting, J. [Elsam, Fredericia (Denmark)

    2004-07-01

    This paper dsecribes VPPT (Wind Power Prediction Tool), an application for assessing the future available wind power up to 36 hours ahead in time. WPPT has been installed in the Eltra/Elsam central dispatch center since October 1997. The paper describes the prediction model used, the actual implementation of WPPT as well as the experience gained by the operators in the dispatch center (au)

  7. Prediction of Wind Energy Resources (PoWER) Users Guide

    Science.gov (United States)

    2016-01-01

    ARL-TR-7573● JAN 2016 US Army Research Laboratory Prediction of Wind Energy Resources (PoWER) User’s Guide by David P Sauter...manufacturer’s or trade names does not constitute an official endorsement or approval of the use thereof. Destroy this report when it is no longer needed. Do...not return it to the originator. ARL-TR-7573 ● JAN 2016 US Army Research Laboratory Prediction of Wind Energy Resources (PoWER

  8. Frequency weighted model predictive control of wind turbine

    DEFF Research Database (Denmark)

    Klauco, Martin; Poulsen, Niels Kjølstad; Mirzaei, Mahmood

    2013-01-01

    This work is focused on applying frequency weighted model predictive control (FMPC) on three blade horizontal axis wind turbine (HAWT). A wind turbine is a very complex, non-linear system influenced by a stochastic wind speed variation. The reduced dynamics considered in this work are the rotatio...... predictive controller are presented. Statistical comparison between frequency weighted MPC, standard MPC and baseline PI controller is shown as well.......This work is focused on applying frequency weighted model predictive control (FMPC) on three blade horizontal axis wind turbine (HAWT). A wind turbine is a very complex, non-linear system influenced by a stochastic wind speed variation. The reduced dynamics considered in this work...... are the rotational degree of freedom of the rotor and the tower for-aft movement. The MPC design is based on a receding horizon policy and a linearised model of the wind turbine. Due to the change of dynamics according to wind speed, several linearisation points must be considered and the control design adjusted...

  9. Model Predictive Control of Wind Turbines using Uncertain LIDAR Measurements

    DEFF Research Database (Denmark)

    Mirzaei, Mahmood; Soltani, Mohsen; Poulsen, Niels Kjølstad

    2013-01-01

    , we simplify state prediction for the MPC. Consequently, the control problem of the nonlinear system is simplified into a quadratic programming. We consider uncertainty in the wind propagation time, which is the traveling time of wind from the LIDAR measurement point to the rotor. An algorithm based......The problem of Model predictive control (MPC) of wind turbines using uncertain LIDAR (LIght Detection And Ranging) measurements is considered. A nonlinear dynamical model of the wind turbine is obtained. We linearize the obtained nonlinear model for different operating points, which are determined...... on wind speed estimation and measurements from the LIDAR is devised to find an estimate of the delay and compensate for it before it is used in the controller. Comparisons between the MPC with error compensation, the MPC without error compensation and an MPC with re-linearization at each sample point...

  10. Probabilistic maximum-value wind prediction for offshore environments

    DEFF Research Database (Denmark)

    Staid, Andrea; Pinson, Pierre; Guikema, Seth D.

    2015-01-01

    statistical models to predict the full distribution of the maximum-value wind speeds in a 3 h interval. We take a detailed look at the performance of linear models, generalized additive models and multivariate adaptive regression splines models using meteorological covariates such as gust speed, wind speed......, convective available potential energy, Charnock, mean sea-level pressure and temperature, as given by the European Center for Medium-Range Weather Forecasts forecasts. The models are trained to predict the mean value of maximum wind speed, and the residuals from training the models are used to develop...... the full probabilistic distribution of maximum wind speed. Knowledge of the maximum wind speed for an offshore location within a given period can inform decision-making regarding turbine operations, planned maintenance operations and power grid scheduling in order to improve safety and reliability...

  11. Evaluation of different machine learning models for predicting and mapping the susceptibility of gully erosion

    Science.gov (United States)

    Rahmati, Omid; Tahmasebipour, Nasser; Haghizadeh, Ali; Pourghasemi, Hamid Reza; Feizizadeh, Bakhtiar

    2017-12-01

    Gully erosion constitutes a serious problem for land degradation in a wide range of environments. The main objective of this research was to compare the performance of seven state-of-the-art machine learning models (SVM with four kernel types, BP-ANN, RF, and BRT) to model the occurrence of gully erosion in the Kashkan-Poldokhtar Watershed, Iran. In the first step, a gully inventory map consisting of 65 gully polygons was prepared through field surveys. Three different sample data sets (S1, S2, and S3), including both positive and negative cells (70% for training and 30% for validation), were randomly prepared to evaluate the robustness of the models. To model the gully erosion susceptibility, 12 geo-environmental factors were selected as predictors. Finally, the goodness-of-fit and prediction skill of the models were evaluated by different criteria, including efficiency percent, kappa coefficient, and the area under the ROC curves (AUC). In terms of accuracy, the RF, RBF-SVM, BRT, and P-SVM models performed excellently both in the degree of fitting and in predictive performance (AUC values well above 0.9), which resulted in accurate predictions. Therefore, these models can be used in other gully erosion studies, as they are capable of rapidly producing accurate and robust gully erosion susceptibility maps (GESMs) for decision-making and soil and water management practices. Furthermore, it was found that performance of RF and RBF-SVM for modelling gully erosion occurrence is quite stable when the learning and validation samples are changed.

  12. Wind Plant Performance Prediction (WP3) Project

    Energy Technology Data Exchange (ETDEWEB)

    Craig, Anna [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2018-01-26

    The methods for analysis of operational wind plant data are highly variable across the wind industry, leading to high uncertainties in the validation and bias-correction of preconstruction energy estimation methods. Lack of credibility in the preconstruction energy estimates leads to significant impacts on project financing and therefore the final levelized cost of energy for the plant. In this work, the variation in the evaluation of a wind plant's operational energy production as a result of variations in the processing methods applied to the operational data is examined. Preliminary results indicate that selection of the filters applied to the data and the filter parameters can have significant impacts in the final computed assessment metrics.

  13. Using machine learning to predict wind turbine power output

    International Nuclear Information System (INIS)

    Clifton, A; Kilcher, L; Lundquist, J K; Fleming, P

    2013-01-01

    Wind turbine power output is known to be a strong function of wind speed, but is also affected by turbulence and shear. In this work, new aerostructural simulations of a generic 1.5 MW turbine are used to rank atmospheric influences on power output. Most significant is the hub height wind speed, followed by hub height turbulence intensity and then wind speed shear across the rotor disk. These simulation data are used to train regression trees that predict the turbine response for any combination of wind speed, turbulence intensity, and wind shear that might be expected at a turbine site. For a randomly selected atmospheric condition, the accuracy of the regression tree power predictions is three times higher than that from the traditional power curve methodology. The regression tree method can also be applied to turbine test data and used to predict turbine performance at a new site. No new data are required in comparison to the data that are usually collected for a wind resource assessment. Implementing the method requires turbine manufacturers to create a turbine regression tree model from test site data. Such an approach could significantly reduce bias in power predictions that arise because of the different turbulence and shear at the new site, compared to the test site. (letter)

  14. Empirical models for predicting wind potential for wind energy applications in rural locations of Nigeria

    Energy Technology Data Exchange (ETDEWEB)

    Odo, F.C. [National Centre for Energy Research and Development, University of Nigeria, Nsukka (Nigeria); Department of Physics and Astronomy, University of Nigeria, Nsukka (Nigeria); Akubue, G.U.; Offiah, S.U.; Ugwuoke, P.E. [National Centre for Energy Research and Development, University of Nigeria, Nsukka (Nigeria)

    2013-07-01

    In this paper, we use the correlation between the average wind speed and ambient temperature to develop models for predicting wind potentials for two Nigerian locations. Assuming that the troposphere is a typical heterogeneous mixture of ideal gases, we find that for the studied locations, wind speed clearly correlates with ambient temperature in a simple polynomial of 3rd degree. The coefficient of determination and root-mean-square error of the models are 0.81; 0.0024 and 0.56; 0.0041, respectively, for Enugu (6.40N; 7.50E) and Owerri (5.50N; 7.00E). These results suggest that the temperature-based model can be used, with acceptable accuracy, in predicting wind potentials needed for preliminary design assessment of wind energy conversion devices for the locations and others with similar meteorological conditions.

  15. A new ensemble model for short term wind power prediction

    DEFF Research Database (Denmark)

    Madsen, Henrik; Albu, Razvan-Daniel; Felea, Ioan

    2012-01-01

    As the objective of this study, a non-linear ensemble system is used to develop a new model for predicting wind speed in short-term time scale. Short-term wind power prediction becomes an extremely important field of research for the energy sector. Regardless of the recent advancements in the re-search...... of prediction models, it was observed that different models have different capabilities and also no single model is suitable under all situations. The idea behind EPS (ensemble prediction systems) is to take advantage of the unique features of each subsystem to detain diverse patterns that exist in the dataset...

  16. Prediction for disruption erosion of ITER plasma facing components; a comparison of experimental and numerical results

    International Nuclear Information System (INIS)

    Laan, J.G. van der; Akiba, M.; Seki, M.; Hassanein, A.; Tanchuk, V.

    1991-01-01

    An evaluation is given for the prediction for disruption erosion in the International Thermonuclear Engineering Reactor (ITER). At first, a description is given of the relation between plasma operating paramters and system dimensions to the predictions of loading parameters of Plasma Facing Components (PFC) in off-normal events. Numerical results from ITER parties on the prediction of disruption erosion are compared for a few typical cases and discussed. Apart from some differences in the codes, the observed discrepancies can be ascribed to different input data of material properties and boundary conditions. Some physical models for vapour shielding and their effects on numerical results are mentioned. Experimental results from ITER parties, obtained with electron and laser beams, are also compared. Erosion rates for the candidate ITER PFC materials are shown to depend very strongly on the energy deposition parameters, which are based on plasma physics considerations, and on the assumed material loss mechanisms. Lifetimes estimates for divertor plate and first wall armour are given for carbon, tungsten and beryllium, based on the erosion in the thermal quench phase. (orig.)

  17. Optimal prediction intervals of wind power generation

    DEFF Research Database (Denmark)

    Wan, Can; Wu, Zhao; Pinson, Pierre

    2014-01-01

    direct optimization of both the coverage probability and sharpness to ensure the quality. The proposed method does not involve the statistical inference or distribution assumption of forecasting errors needed in most existing methods. Case studies using real wind farm data from Australia have been...

  18. Selection of References in Wind Turbine Model Predictive Control Design

    DEFF Research Database (Denmark)

    Odgaard, Peter Fogh; Hovgaard, Tobias

    2015-01-01

    a model predictive controller for a wind turbine. One of the important aspects for a tracking control problem is how to setup the optimal reference tracking problem, as it might be relevant to track, e.g., the three concurrent references: optimal pitch angle, optimal rotational speed, and optimal power......Lowering the cost of energy is one of the major focus areas in the wind turbine industry. Recent research has indicated that wind turbine controllers based on model predictive control methods can be useful in obtaining this objective. A number of design considerations have to be made when designing....... The importance if the individual references differ depending in particular on the wind speed. In this paper we investigate the performance of a reference tracking model predictive controller with two different setups of the used optimal reference signals. The controllers are evaluated using an industrial high...

  19. Error analysis of short term wind power prediction models

    International Nuclear Information System (INIS)

    De Giorgi, Maria Grazia; Ficarella, Antonio; Tarantino, Marco

    2011-01-01

    The integration of wind farms in power networks has become an important problem. This is because the electricity produced cannot be preserved because of the high cost of storage and electricity production must follow market demand. Short-long-range wind forecasting over different lengths/periods of time is becoming an important process for the management of wind farms. Time series modelling of wind speeds is based upon the valid assumption that all the causative factors are implicitly accounted for in the sequence of occurrence of the process itself. Hence time series modelling is equivalent to physical modelling. Auto Regressive Moving Average (ARMA) models, which perform a linear mapping between inputs and outputs, and Artificial Neural Networks (ANNs) and Adaptive Neuro-Fuzzy Inference Systems (ANFIS), which perform a non-linear mapping, provide a robust approach to wind power prediction. In this work, these models are developed in order to forecast power production of a wind farm with three wind turbines, using real load data and comparing different time prediction periods. This comparative analysis takes in the first time, various forecasting methods, time horizons and a deep performance analysis focused upon the normalised mean error and the statistical distribution hereof in order to evaluate error distribution within a narrower curve and therefore forecasting methods whereby it is more improbable to make errors in prediction. (author)

  20. Error analysis of short term wind power prediction models

    Energy Technology Data Exchange (ETDEWEB)

    De Giorgi, Maria Grazia; Ficarella, Antonio; Tarantino, Marco [Dipartimento di Ingegneria dell' Innovazione, Universita del Salento, Via per Monteroni, 73100 Lecce (Italy)

    2011-04-15

    The integration of wind farms in power networks has become an important problem. This is because the electricity produced cannot be preserved because of the high cost of storage and electricity production must follow market demand. Short-long-range wind forecasting over different lengths/periods of time is becoming an important process for the management of wind farms. Time series modelling of wind speeds is based upon the valid assumption that all the causative factors are implicitly accounted for in the sequence of occurrence of the process itself. Hence time series modelling is equivalent to physical modelling. Auto Regressive Moving Average (ARMA) models, which perform a linear mapping between inputs and outputs, and Artificial Neural Networks (ANNs) and Adaptive Neuro-Fuzzy Inference Systems (ANFIS), which perform a non-linear mapping, provide a robust approach to wind power prediction. In this work, these models are developed in order to forecast power production of a wind farm with three wind turbines, using real load data and comparing different time prediction periods. This comparative analysis takes in the first time, various forecasting methods, time horizons and a deep performance analysis focused upon the normalised mean error and the statistical distribution hereof in order to evaluate error distribution within a narrower curve and therefore forecasting methods whereby it is more improbable to make errors in prediction. (author)

  1. Model Predictive Voltage Control of Wind Power Plants

    DEFF Research Database (Denmark)

    Zhao, Haoran; Wu, Qiuwei

    2018-01-01

    the efficacy of the proposed WFVC, two case scenarios were designed: the wind farm is under normal operating conditions and the internal wind power fluctuation is considered; and besides internal power fluctuation, the impact of the external grid on the wind farm is considered.......This chapter proposes an autonomous wind farm voltage controller (WFVC) based on model predictive control (MPC). It also introduces the analytical expressions for the voltage sensitivity to tap positions of a transformer. The chapter then describes the discrete models for the wind turbine...... generators (WTGs) and static var compensators (SVCs)/static var generators (SVGs). Next, it describes the implementation of the on‐load tap changing (OLTC) in the MPC. Furthermore, the chapter examines the cost function as well as the constraints of the MPC‐based WFVC for both control modes. In order to test...

  2. Improved USLE-K factor prediction: A case study on water erosion areas in China

    Directory of Open Access Journals (Sweden)

    Bin Wang

    2016-09-01

    Full Text Available Soil erodibility (K-factor is an essential factor in soil erosion prediction and conservation practises. The major obstacles to any accurate, large-scale soil erodibility estimation are the lack of necessary data on soil characteristics and the misuse of variable K-factor calculators. In this study, we assessed the performance of available erodibility estimators Universal Soil Loss Equation (USLE, Revised Universal Soil Loss Equation (RUSLE, Erosion Productivity Impact Calculator (EPIC and the Geometric Mean Diameter based (Dg model for different geographic regions based on the Chinese soil erodibility database (CSED. Results showed that previous estimators overestimated almost all K-values. Furthermore, only the USLE and Dg approaches could be directly and reliably applicable to black and loess soil regions. Based on the nonlinear best fitting techniques, we improved soil erodibility prediction by combining Dg and soil organic matter (SOM. The NSE, R2 and RE values were 0.94, 0.67 and 9.5% after calibrating the results independently; similar model performance was showed for the validation process. The results obtained via the proposed approach were more accurate that the former K-value predictions. Moreover, those improvements allowed us to effectively establish a regional soil erodibility map (1:250,000 scale of water erosion areas in China. The mean K-value of Chinese water erosion regions was 0.0321 (t ha h·(ha MJ mm−1 with a standard deviation of 0.0107 (t ha h·(ha MJ mm−1; K-values present a decreasing trend from North to South in water erosion areas in China. The yield soil erodibility dataset also satisfactorily corresponded to former K-values from different scales (local, regional, and national.

  3. Short-term prediction of local wind conditions

    DEFF Research Database (Denmark)

    Landberg, L.

    2001-01-01

    This paper will describe a system which predicts the expected power output of a number of wind farms. The system is automatic and operates on-line. The paper will quantify the accuracy of the predictions and will also give examples of the performance for specific storm events. An actual...

  4. Robust Model Predictive Control of a Wind Turbine

    DEFF Research Database (Denmark)

    Mirzaei, Mahmood; Poulsen, Niels Kjølstad; Niemann, Hans Henrik

    2012-01-01

    In this work the problem of robust model predictive control (robust MPC) of a wind turbine in the full load region is considered. A minimax robust MPC approach is used to tackle the problem. Nonlinear dynamics of the wind turbine are derived by combining blade element momentum (BEM) theory...... of the uncertain system is employed and a norm-bounded uncertainty model is used to formulate a minimax model predictive control. The resulting optimization problem is simplified by semidefinite relaxation and the controller obtained is applied on a full complexity, high fidelity wind turbine model. Finally...... and first principle modeling of the turbine flexible structure. Thereafter the nonlinear model is linearized using Taylor series expansion around system operating points. Operating points are determined by effective wind speed and an extended Kalman filter (EKF) is employed to estimate this. In addition...

  5. Improving urban wind flow predictions through data assimilation

    Science.gov (United States)

    Sousa, Jorge; Gorle, Catherine

    2017-11-01

    Computational fluid dynamic is fundamentally important to several aspects in the design of sustainable and resilient urban environments. The prediction of the flow pattern for example can help to determine pedestrian wind comfort, air quality, optimal building ventilation strategies, and wind loading on buildings. However, the significant variability and uncertainty in the boundary conditions poses a challenge when interpreting results as a basis for design decisions. To improve our understanding of the uncertainties in the models and develop better predictive tools, we started a pilot field measurement campaign on Stanford University's campus combined with a detailed numerical prediction of the wind flow. The experimental data is being used to investigate the potential use of data assimilation and inverse techniques to better characterize the uncertainty in the results and improve the confidence in current wind flow predictions. We consider the incoming wind direction and magnitude as unknown parameters and perform a set of Reynolds-averaged Navier-Stokes simulations to build a polynomial chaos expansion response surface at each sensor location. We subsequently use an inverse ensemble Kalman filter to retrieve an estimate for the probabilistic density function of the inflow parameters. Once these distributions are obtained, the forward analysis is repeated to obtain predictions for the flow field in the entire urban canopy and the results are compared with the experimental data. We would like to acknowledge high-performance computing support from Yellowstone (ark:/85065/d7wd3xhc) provided by NCAR.

  6. Artificial intelligence to predict short-term wind speed

    Energy Technology Data Exchange (ETDEWEB)

    Pinto, Tiago; Soares, Joao; Ramos, Sergio; Vale, Zita [Polytechnic of Porto (Portugal). GECAD - ISEP

    2012-07-01

    The use of renewable energy is increasing exponentially in many countries due to the introduction of new energy and environmental policies. Thus, the focus on energy and on the environment makes the efficient integration of renewable energy into the electric power system extremely important. Several European countries have been seeing a high penetration of wind power, representing, gradually, a significant penetration on electricity generation. The introduction of wind power in the network power system causes new challenges for the power system operator due to the variability and uncertainty in weather conditions and, consequently, in the wind power generation. As result, the scheduling dispatch has a significantly portion of uncertainty. In order to deal with the uncertainty in wind power and, with that, introduce improvements in the power system operator efficiency, the wind power forecasting may reveal as a useful tool. This paper proposes a data-mining-based methodology to forecast wind speed. This method is based on the use of data mining techniques applied to a real database of historical wind data. The paper includes a case study based on a real database regarding the last three years to predict wind speed at 5 minute intervals. (orig.)

  7. Research on wind field algorithm of wind lidar based on BP neural network and grey prediction

    Science.gov (United States)

    Chen, Yong; Chen, Chun-Li; Luo, Xiong; Zhang, Yan; Yang, Ze-hou; Zhou, Jie; Shi, Xiao-ding; Wang, Lei

    2018-01-01

    This paper uses the BP neural network and grey algorithm to forecast and study radar wind field. In order to reduce the residual error in the wind field prediction which uses BP neural network and grey algorithm, calculating the minimum value of residual error function, adopting the residuals of the gray algorithm trained by BP neural network, using the trained network model to forecast the residual sequence, using the predicted residual error sequence to modify the forecast sequence of the grey algorithm. The test data show that using the grey algorithm modified by BP neural network can effectively reduce the residual value and improve the prediction precision.

  8. Hourly Wind Speed Interval Prediction in Arid Regions

    Science.gov (United States)

    Chaouch, M.; Ouarda, T.

    2013-12-01

    context, probabilistic forecasts might be more relevant than point forecasts for the planner to build scenarios In this paper, we are interested in estimating predictive intervals of the hourly wind speed measures in few cities in United Arab emirates (UAE). More precisely, given a wind speed time series, our target is to forecast the wind speed at any specific hour during the day and provide in addition an interval with the coverage probability 0flexible because it does not need a specification of the model to work with (such as normal distribution or a linear relation). Here, we use a covariable that is correlated to the wind speed. In practice, many possible choices of the covariate are available. In fact, in addition to its historical data, the wind speed is highly correlated to temperature, humidity and wind direction. In this paper a comparison, in terms of Mean Absolute Prediction Errors and Interquartile Range, between those choices will be provided to show which covariates are more suitable to forecast wind speed.

  9. Model output statistics applied to wind power prediction

    Energy Technology Data Exchange (ETDEWEB)

    Joensen, A; Giebel, G; Landberg, L [Risoe National Lab., Roskilde (Denmark); Madsen, H; Nielsen, H A [The Technical Univ. of Denmark, Dept. of Mathematical Modelling, Lyngby (Denmark)

    1999-03-01

    Being able to predict the output of a wind farm online for a day or two in advance has significant advantages for utilities, such as better possibility to schedule fossil fuelled power plants and a better position on electricity spot markets. In this paper prediction methods based on Numerical Weather Prediction (NWP) models are considered. The spatial resolution used in NWP models implies that these predictions are not valid locally at a specific wind farm. Furthermore, due to the non-stationary nature and complexity of the processes in the atmosphere, and occasional changes of NWP models, the deviation between the predicted and the measured wind will be time dependent. If observational data is available, and if the deviation between the predictions and the observations exhibits systematic behavior, this should be corrected for; if statistical methods are used, this approaches is usually referred to as MOS (Model Output Statistics). The influence of atmospheric turbulence intensity, topography, prediction horizon length and auto-correlation of wind speed and power is considered, and to take the time-variations into account, adaptive estimation methods are applied. Three estimation techniques are considered and compared, Extended Kalman Filtering, recursive least squares and a new modified recursive least squares algorithm. (au) EU-JOULE-3. 11 refs.

  10. Skill forecasting from different wind power ensemble prediction methods

    International Nuclear Information System (INIS)

    Pinson, Pierre; Nielsen, Henrik A; Madsen, Henrik; Kariniotakis, George

    2007-01-01

    This paper presents an investigation on alternative approaches to the providing of uncertainty estimates associated to point predictions of wind generation. Focus is given to skill forecasts in the form of prediction risk indices, aiming at giving a comprehensive signal on the expected level of forecast uncertainty. Ensemble predictions of wind generation are used as input. A proposal for the definition of prediction risk indices is given. Such skill forecasts are based on the dispersion of ensemble members for a single prediction horizon, or over a set of successive look-ahead times. It is shown on the test case of a Danish offshore wind farm how prediction risk indices may be related to several levels of forecast uncertainty (and energy imbalances). Wind power ensemble predictions are derived from the transformation of ECMWF and NCEP ensembles of meteorological variables to power, as well as by a lagged average approach alternative. The ability of risk indices calculated from the various types of ensembles forecasts to resolve among situations with different levels of uncertainty is discussed

  11. Soil erosion model predictions using parent material/soil texture-based parameters compared to using site-specific parameters

    Science.gov (United States)

    R. B. Foltz; W. J. Elliot; N. S. Wagenbrenner

    2011-01-01

    Forested areas disturbed by access roads produce large amounts of sediment. One method to predict erosion and, hence, manage forest roads is the use of physically based soil erosion models. A perceived advantage of a physically based model is that it can be parameterized at one location and applied at another location with similar soil texture or geological parent...

  12. Pelton turbine Needle erosion prediction based on 3D three- phase flow simulation

    International Nuclear Information System (INIS)

    Chongji, Z; Yexiang, X; Wei, Z; Yangyang, Y; Lei, C; Zhengwei, W

    2014-01-01

    Pelton turbine, which applied to the high water head and small flow rate, is widely used in the mountainous area. During the operation period the sediment contained in the water does not only induce the abrasion of the buckets, but also leads to the erosion at the nozzle which may damage the needle structure. The nozzle and needle structure are mainly used to form high quality cylindrical jet and increase the efficiency of energy exchange in the runner to the most. Thus the needle erosion will lead to the deformation of jet, and then may cause the efficiency loss and cavitation. The favourable prediction of abrasion characteristic of needle can effectively guide the optimization design and maintenance of needle structure. This paper simulated the unsteady three-dimensional multi-phase flow in the nozzle and injected jet flow. As the jet containing water and sediment is injected into the free atmosphere air with high velocity, the VOF model was adopted to predict the water and air flow. The sediment is simplified into round solid particle and the discrete particle model (DPM) was employed to predict the needle abrasion characteristic. The sand particle tracks were analyzed to interpret the mechanism of sand erosion on the needle surface. And the numerical result of needle abrasion was obtained and compared with the abrasion field observation. The similarity of abrasion pattern between the numerical results and field observation illustrated the validity of the 3D multi-phase flow simulation method

  13. Pelton turbine Needle erosion prediction based on 3D three- phase flow simulation

    Science.gov (United States)

    Chongji, Z.; Yexiang, X.; Wei, Z.; Yangyang, Y.; Lei, C.; Zhengwei, W.

    2014-03-01

    Pelton turbine, which applied to the high water head and small flow rate, is widely used in the mountainous area. During the operation period the sediment contained in the water does not only induce the abrasion of the buckets, but also leads to the erosion at the nozzle which may damage the needle structure. The nozzle and needle structure are mainly used to form high quality cylindrical jet and increase the efficiency of energy exchange in the runner to the most. Thus the needle erosion will lead to the deformation of jet, and then may cause the efficiency loss and cavitation. The favourable prediction of abrasion characteristic of needle can effectively guide the optimization design and maintenance of needle structure. This paper simulated the unsteady three-dimensional multi-phase flow in the nozzle and injected jet flow. As the jet containing water and sediment is injected into the free atmosphere air with high velocity, the VOF model was adopted to predict the water and air flow. The sediment is simplified into round solid particle and the discrete particle model (DPM) was employed to predict the needle abrasion characteristic. The sand particle tracks were analyzed to interpret the mechanism of sand erosion on the needle surface. And the numerical result of needle abrasion was obtained and compared with the abrasion field observation. The similarity of abrasion pattern between the numerical results and field observation illustrated the validity of the 3D multi-phase flow simulation method.

  14. Wind farm production prediction - The Zephyr model

    Energy Technology Data Exchange (ETDEWEB)

    Landberg, L. [Risoe National Lab., Wind Energy Dept., Roskilde (Denmark); Giebel, G. [Risoe National Lab., Wind Energy Dept., Roskilde (Denmark); Madsen, H. [IMM (DTU), Kgs. Lyngby (Denmark); Nielsen, T.S. [IMM (DTU), Kgs. Lyngby (Denmark); Joergensen, J.U. [Danish Meteorologisk Inst., Copenhagen (Denmark); Lauersen, L. [Danish Meteorologisk Inst., Copenhagen (Denmark); Toefting, J. [Elsam, Fredericia (DK); Christensen, H.S. [Eltra, Fredericia (Denmark); Bjerge, C. [SEAS, Haslev (Denmark)

    2002-06-01

    This report describes a project - funded by the Danish Ministry of Energy and the Environment - which developed a next generation prediction system called Zephyr. The Zephyr system is a merging between two state-of-the-art prediction systems: Prediktor of Risoe National Laboratory and WPPT of IMM at the Danish Technical University. The numerical weather predictions were generated by DMI's HIRLAM model. Due to technical difficulties programming the system, only the computational core and a very simple version of the originally very complex system were developed. The project partners were: Risoe, DMU, DMI, Elsam, Eltra, Elkraft System, SEAS and E2. (au)

  15. Predicting Ultimate Loads for Wind Turbine Design

    International Nuclear Information System (INIS)

    Madsen, P. H.; Pierce, K.; Buhl, M.

    1998-01-01

    This paper addresses the statistical uncertainty of loads prediction using structural dynamics simulation codes and the requirements for the number and duration of simulations for obtaining robust load estimates

  16. Vertical Wind Tunnel for Prediction of Rocket Flight Dynamics

    Directory of Open Access Journals (Sweden)

    Hoani Bryson

    2016-03-01

    Full Text Available A customized vertical wind tunnel has been built by the University of Canterbury Rocketry group (UC Rocketry. This wind tunnel has been critical for the success of UC Rocketry as it allows the optimization of avionics and control systems before flight. This paper outlines the construction of the wind tunnel and includes an analysis of flow quality including swirl. A minimal modelling methodology for roll dynamics is developed that can extrapolate wind tunnel behavior at low wind speeds to much higher velocities encountered during flight. The models were shown to capture the roll flight dynamics in two rocket launches with mean roll angle errors varying from 0.26° to 1.5° across the flight data. The identified model parameters showed consistent and predictable variations over both wind tunnel tests and flight, including canard–fin interaction behavior. These results demonstrate that the vertical wind tunnel is an important tool for the modelling and control of sounding rockets.

  17. Measurement and data analysis methods for field-scale wind erosion studies and model validation

    NARCIS (Netherlands)

    Zobeck, T.M.; Sterk, G.; Funk, R.F.; Rajot, J.L.; Stout, J.E.; Scott Van Pelt, R.

    2003-01-01

    Accurate and reliable methods of measuring windblown sediment are needed to confirm, validate, and improve erosion models, assess the intensity of aeolian processes and related damage, determine the source of pollutants, and for other applications. This paper outlines important principles to

  18. Wind reduction patterns around isolated biomass for wind erosion control in a desertified area of Central Sudan

    NARCIS (Netherlands)

    Nasr Al-amin, N.K.; Stigter, C.J.; El-Tayeb Mohammed, A.

    2010-01-01

    The aim of this study was to assess the effectiveness of sparse vegetation, feature common in arid zone, to reduce wind force (velocity) and hence protect the surface and regions downwind from drifting sand and their consequences. Respectively 4 (with heights h of 4, 3.2, 2 and 1.66 m), 2 (with h of

  19. Aerodynamic performance prediction of Darrieus-type wind turbines

    Directory of Open Access Journals (Sweden)

    Ion NILĂ

    2010-06-01

    Full Text Available The prediction of Darrieus wind turbine aerodynamic performances provides the necessarydesign and operational data base related to the wind potential. In this sense it provides the type ofturbine suitable to the area where it is to be installed. Two calculation methods are analyzed for arotor with straight blades. The first one is a global method that allows an assessment of the turbinenominal power by a brief calculation. This method leads to an overestimation of performances. Thesecond is the calculation method of the gust factor and momentum which deals with the pale as beingcomposed of different elements that don’t influence each other. This method, developed based on thetheory of the turbine blades, leads to values close to the statistical data obtained experimentally. Thevalues obtained by the calculation method of gust factor - momentum led to the concept of a Darrieusturbine, which will be tested for different wind values in the INCAS subsonic wind tunnel.

  20. Model predictive control of wind energy conversion systems

    CERN Document Server

    Yaramasu, Venkata Narasimha R

    2017-01-01

    The authors provide a comprehensive analysis on the model predictive control of power converters employed in a wide variety of variable-speed wind energy conversion systems (WECS). The contents of this book includes an overview of wind energy system configurations, power converters for variable-speed WECS, digital control techniques, MPC, modeling of power converters and wind generators for MPC design. Other topics include the mapping of continuous-time models to discrete-time models by various exact, approximate, and quasi-exact discretization methods, modeling and control of wind turbine grid-side two-level and multilevel voltage source converters. The authors also focus on the MPC of several power converter configurations for full variable-speed permanent magnet synchronous generator based WECS, squirrel-cage induction generator based WECS, and semi-variable-speed doubly fed induction generator based WECS.

  1. Three-model ensemble wind prediction in southern Italy

    Science.gov (United States)

    Torcasio, Rosa Claudia; Federico, Stefano; Calidonna, Claudia Roberta; Avolio, Elenio; Drofa, Oxana; Landi, Tony Christian; Malguzzi, Piero; Buzzi, Andrea; Bonasoni, Paolo

    2016-03-01

    Quality of wind prediction is of great importance since a good wind forecast allows the prediction of available wind power, improving the penetration of renewable energies into the energy market. Here, a 1-year (1 December 2012 to 30 November 2013) three-model ensemble (TME) experiment for wind prediction is considered. The models employed, run operationally at National Research Council - Institute of Atmospheric Sciences and Climate (CNR-ISAC), are RAMS (Regional Atmospheric Modelling System), BOLAM (BOlogna Limited Area Model), and MOLOCH (MOdello LOCale in H coordinates). The area considered for the study is southern Italy and the measurements used for the forecast verification are those of the GTS (Global Telecommunication System). Comparison with observations is made every 3 h up to 48 h of forecast lead time. Results show that the three-model ensemble outperforms the forecast of each individual model. The RMSE improvement compared to the best model is between 22 and 30 %, depending on the season. It is also shown that the three-model ensemble outperforms the IFS (Integrated Forecasting System) of the ECMWF (European Centre for Medium-Range Weather Forecast) for the surface wind forecasts. Notably, the three-model ensemble forecast performs better than each unbiased model, showing the added value of the ensemble technique. Finally, the sensitivity of the three-model ensemble RMSE to the length of the training period is analysed.

  2. WSA-Enlil Solar Wind Prediction

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — WSA-Enlil is a large-scale, physics-based prediction model of the heliosphere, used by the Space Weather Forecast Office to provide 1-4 day advance warning of solar...

  3. [Advance in researches on vegetation cover and management factor in the soil erosion prediction model].

    Science.gov (United States)

    Zhang, Yan; Yuan, Jianping; Liu, Baoyuan

    2002-08-01

    Vegetation cover and land management are the main limiting factors of soil erosion, and quantitative evaluation on the effect of different vegetation on soil erosion is essential to land use and soil conservation planning. The vegetation cover and management factor (C) in the universal soil loss equation (USLE) is an index to evaluate this effect, which has been studied deeply and used widely. However, the C factor study is insufficient in China. In order to strengthen the research of C factor, this paper reviewed the developing progress of C factor, and compared the methods of estimating C value in different USLE versions. The relative studies in China were also summarized from the aspects of vegetation canopy coverage, soil surface cover, and root density. Three problems in C factor study were pointed out. The authors suggested that cropland C factor research should be furthered, and its methodology should be unified in China to represent reliable C values for soil loss prediction and conservation planning.

  4. Forecasting Electricity Spot Prices Accounting for Wind Power Predictions

    DEFF Research Database (Denmark)

    Jónsson, Tryggvi; Pinson, Pierre; Nielsen, Henrik Aalborg

    2013-01-01

    A two-step methodology for forecasting of electricity spot prices is introduced, with focus on the impact of predicted system load and wind power generation. The nonlinear and nonstationary influence of these explanatory variables is accommodated in a first step based on a nonparametric and time...

  5. Prediction of wind energy distribution in complex terrain using CFD

    DEFF Research Database (Denmark)

    Xu, Chang; Li, Chenqi; Yang, Jianchuan

    2013-01-01

    Based on linear models, WAsP software predicts wind energy distribution, with a good accuracy for flat terrain, but with a large error under complicated topography. In this paper, numerical simulations are carried out using the FLUENT software on a mesh generated by the GAMBIT and ARGIS software ...

  6. Dust records in the Pleistocene sediments of Fraser Island: palaeoclimatic reconstruction of wind erosion over the last 600 ka

    International Nuclear Information System (INIS)

    Longmore, M.E.; McTainsh, G.H.

    1997-01-01

    Full text: Pleistocene lake sediments from a relic perched freshwater lake on Fraser Island have been found to date back to ca.600 ka using U/Th analysis of the organics. This sequence is one of the three longest terrestrial records of environmental change in Australia and the contained evidence of vegetation, fire and lake level changes (Longmore and Heijnis, 1996) and is an invaluable contribution to palaeoclimatic reconstruction. A younger sequence, dated by conventional radiocarbon analysis, has 6.5 m of continuous organic sedimentation from ca. 30 ka to the present. The last 8.5 ka has been analysed in detail, showing a mid-Holocene 'dry' period (Longmore, 1996). Continental aeolian dust from extreme wind erosional events has been measured in modern atmospheres (McTainsh, 1989; Knight et al., 1995) and deep sea cores (Hesse, 1994), but the terrestrial record of wind erosion during the Pleistocene is sparse. We will report on a pilot project to determine the presence of aeolian dust from extreme wind erosional events in the past in the sediments of Fraser Island lakes. Due to the highly weathered, well-sorted, siliceous nature of the dune sands forming the Island and the highly organic nature of the lake sediments (80-95% LOI), these are some of the few terrestrial sequences that permit separation of aeolian dust from local catchment materials. In the future, oxygen isotope and XRD analysis of the extracted dust will allow the most likely source of the entrained material to be determined and thus provide further evidence as to the wind regime during the last 600ka and 30ka respectively. The separation of dust from these terrestrial sequences is a major achievement and potentially may make a significant contribution to global palaeoclimatic models

  7. Wind erosion risk in the southwest of Buenos Aires Province, Argentina, and its relationship to the productivity index

    Science.gov (United States)

    Silenzi, Juan C.; Echeverría, Nora E.; Vallejos, Adrián G.; Bouza, Mariana E.; De Lucia, Martín P.

    2012-01-01

    Wind erosion risk (WER) for soils of each municipality in the southwest (SW) of Buenos Aires Province (10,491,172 ha) was determined using the wind erosion equation (WEQ) model. WER results from multiplying the soil erodibility index (" I") of the soil by the climatic factor ( C). WER (Mg ha -1 year -1) of each municipality was: Bahía Blanca: 22.4, Coronel Dorrego: 18.6, Coronel Pringles: 4.5, Coronel Rosales: 48.2, Coronel Suárez: 4.5, Guaminí: 3.0, Patagones: 104.6, Puan: 12.2, Saavedra: 3.0, Tornquist: 6.8, and Villarino: 31.7. The maximum weighted average of " I" (Mg ha -1 year -1) corresponded to Coronel Rosales (87.6), Patagones (87.2), Villarino (85.7), Puan (67.9); Guaminí (59.6), Coronel Dorrego (53.1), and Bahía Blanca (39.3); the remaining municipalities ranged between 34.9 and 32.1 Mg ha -1 year -1. The highest C (%) corresponded to Patagones (120), Bahía Blanca (57), Coronel Rosales (55), Villarino (37), Coronel Dorrego (35), Tornquist (21), and Puan (18); for the remaining municipalities it was 14%. The productivity index (PI) is known to establish a numerical value of the productive capacity of lands. The relationship between WER and PI, weighted averages, in all the studied municipalities was fitted by means of a linear model, WER (Mg ha -1 year -1) = 95.23 - 2.09 * PI (%) ( R2 = 66%), and a second-order polynomial model, WER (Mg ha -1 year -1) = 139.41 - 5.86 * PI (%) + 0.07 * PI 2 (%) ( R2 = 74%). No statistically significant relationship was found between WER and PI for each municipality.

  8. Interactive effects of moss-dominated crusts and Artemisia ordosica on wind erosion and soil moisture in Mu Us sandland, China.

    Science.gov (United States)

    Yang, Yongsheng; Bu, Chongfeng; Mu, Xingmin; Shao, Hongbo; Zhang, Kankan

    2014-01-01

    To better understand the effects of biological soil crusts (BSCs) on soil moisture and wind erosion and study the necessity and feasibility of disturbance of BSCs in the Mu Us sandland, the effects of four treatments, including moss-dominated crusts alone, Artemisia ordosica alone, bare sand, and Artemisia ordosica combined with moss-dominated crusts, on rainwater infiltration, soil moisture, and annual wind erosion were observed. The major results are as follows. (1) The development of moss-dominated crusts exacerbated soil moisture consumption and had negative effects on soil moisture in the Mu Us sandland. (2) Moss-dominated crusts significantly increased soil resistance to wind erosion, and when combined with Artemisia ordosica, this effect became more significant. The contribution of moss-dominated crusts under Artemisia ordosica was significantly lower than that of moss-dominated crusts alone in sites where vegetative coverage > 50%. (3) Finally, an appropriate disturbance of moss-dominated crusts in the rainy season in sites with high vegetative coverage improved soil water environment and vegetation succession, but disturbance in sites with little or no vegetative cover should be prohibited to avoid the exacerbation of wind erosion.

  9. Using meteorological forecasts in on-line predictions of wind power

    DEFF Research Database (Denmark)

    Nielsen, Torben Skov; Nielsen, Henrik Aalborg; Madsen, Henrik

    1999-01-01

    This report describes a model investigation into wind power prediction model as well as a tool for predicting the power production from wind turbines in an area - the Wind Power Prediction Tool (WPPT). The predictions are based on on-line measurements of power production for a selected set...

  10. Model Predictive Control for Load Frequency Control with Wind Turbines

    Directory of Open Access Journals (Sweden)

    Yi Zhang

    2015-01-01

    Full Text Available Reliable load frequency (LFC control is crucial to the operation and design of modern electric power systems. Considering the LFC problem of a four-area interconnected power system with wind turbines, this paper presents a distributed model predictive control (DMPC based on coordination scheme. The proposed algorithm solves a series of local optimization problems to minimize a performance objective for each control area. The scheme incorporates the two critical nonlinear constraints, for example, the generation rate constraint (GRC and the valve limit, into convex optimization problems. Furthermore, the algorithm reduces the impact on the randomness and intermittence of wind turbine effectively. A performance comparison between the proposed controller with and that without the participation of the wind turbines is carried out. Good performance is obtained in the presence of power system nonlinearities due to the governors and turbines constraints and load change disturbances.

  11. The statistical prediction of offshore winds from land-based data for wind-energy applications

    DEFF Research Database (Denmark)

    Walmsley, J.L.; Barthelmie, R.J.; Burrows, W.R.

    2001-01-01

    Land-based meteorological measurements at two locations on the Danish coast are used to predict offshore wind speeds. Offshore wind-speed data are used only for developing the statistical prediction algorithms and for verification. As a first step, the two datasets were separated into nine...... percentile-based bins, with a minimum of 30 data records in each bin. Next, the records were randomly selected with approximately 70% of the data in each bin being used as a training set for development of the prediction algorithms, and the remaining 30% being reserved as a test set for evaluation purposes....... The binning procedure ensured that both training and test sets fairly represented the overall data distribution. To base the conclusions on firmer ground, five permutations of these training and test sets were created. Thus, all calculations were based on five cases, each one representing a different random...

  12. Development of a mobile application based on RUSLE model to predict erosion in olive groves

    Science.gov (United States)

    Marín Moreno, Víctor Javier; Redel, María Dolores; Taguas, Encarnación V.

    2017-04-01

    Apache Cordova, which are very efficient to facilitate its implementation in most of mobile platforms. The first evaluations from farmers and technicians are also presented in order to improve the first version. References: - Areal, F.J., Riesgo, L., 2014. Farmers' views on the future of olive farming in Andalusia, Spain. Land Use Policy 36 (2014) 543- 553. - CAPyDR, 2016. Aforo de producción de olivar en Andalucía, Campaña 2016-2017. Consejería de Agricultura, Pesca y Desarrollo Rural - Junta de Andalucía. Regional Government of Andalusia, Seville (2016) (Spain) - FAOSTAT -2016. FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS STATISTICS. Accessed at: http://www.fao.org/faostat - Franco, J.A., 2011. Análisis de los factores de participación en programas agroambientales de lucha contra la erosión en el olivar. ITEA 107 (3), 169-183. - Renard, K. G., Foster, G. R., Wessies, G. A., Mccool, D. K., and Yoder, D. C., 1997. Predicting Soil Ero¬sion by Water: A Guide to Conservation Planning with the Revised Universal LossEquation (RUSLE). USDA Agriculture Handbook, No. 703. - Taguas, E.V., Gómez, J.A., 2015. Vulnerability of olive orchards under the current CAP (Common Agricultural Policy) regulations on soil erosion: a study case in Southern Spain. Land Use Policy, 42, 683-694

  13. Wind tunnel tests of biodegradable fugitive dust suppressants being considered to reduce soil erosion by wind at radioactive waste construction sites

    International Nuclear Information System (INIS)

    Ligotke, M.W.; Dennis, G.W.; Bushaw, L.L.

    1993-10-01

    Wind tunnel tests were performed of three fugitive dust control agents derived from potato and sugar beet products. These materials are being considered for use as dust suppressants to reduce the potential for transport of radioactive materials by wind from radioactive waste construction and remediation sites. Soil and dust control agent type, solution concentrations, application quantities, aging (or drying) conditions, surface disturbance, and wind and saltating sand eolian erosive stresses were selected and controlled to simulate application and exposure of excavated soil surfaces in the field. A description of the tests, results, conclusions, and recommendations are presented in this report. The results of this study indicate that all three dust control agents can protect exposed soil surfaces from extreme eolian stresses. It is also clear that the interaction and performance of each agent with various soil types may differ dramatically. Thus, soils similar to that received from ML should be best protected by high concentration (∼2.5%) solutions of potato starch at low water application levels (∼1 to 2 L/m 2 ). Because the effectiveness of PS on this soil type is degraded after a moderate amount of simulated rainfall, other options or additives should be considered if surfaces are to be protected for long intervals or during periods of intermittent rainfall and hot, windy conditions. On the other hand, XDCA should be considered when excavating sandy soils. It should be noted, however, that because the Hanford soil test results are based on a small number of tests, it would be prudent to perform additional tests prior to selecting a fugitive dust control agent for use at the Hanford Site. While fermented potato waste was not the best fixative used on either soil, it did perform reasonably well on both soil types (better than XDCA on Idaho soil and better than PS on Hanford soil)

  14. Parametrization of the increase of the aeolian erosion threshold wind friction velocity due to soil moisture for arid and semi-arid areas

    Directory of Open Access Journals (Sweden)

    F. Fécan

    1999-01-01

    Full Text Available Large-scale simulation of the soil-derived dust emission in semi-arid regions needs to account for the influence of the soil moisture on the wind erosion threshold. Soil water retention consists of molecular adsorption on the soil grain surface and capillary forces between the grain. Interparticle capillary forces (characterized by the moisture tension are the main factor responsible for the increase of the wind erosion threshold observed when the soil moisture increases. When the soil moisture content is close to but smaller than the maximum amount of adsorbed water, w' (depending on the soil texture, these capillary forces are considered as not strong enough to significantly increase the erosion threshold. An expression of the moisture tension as a function of soil moisture and w' is derived from retention curves. From this expression, a parametrization of the ratio of the wet to dry erosion thresholds has been developed as a function of soil moisture and soil texture. The coefficients of this parametrization have been determined by using experimental data from the literature. An empirical relationship between w' and soil clay content has been established. The erosion threshold ratios simulated for different soil textures were found to be in good agreement with the experimental data.Key words. Atmospheric composition and structure (Aerosols and particles · Hydrology (soil moisture

  15. Three procedures for estimating erosion from construction areas

    International Nuclear Information System (INIS)

    Abt, S.R.; Ruff, J.F.

    1978-01-01

    Erosion from many mining and construction sites can lead to serious environmental pollution problems. Therefore, erosion management plans must be developed in order that the engineer may implement measures to control or eliminate excessive soil losses. To properly implement a management program, it is necessary to estimate potential soil losses from the time the project begins to beyond project completion. Three methodologies are presented which project the estimated soil losses due to sheet or rill erosion of water and are applicable to mining and construction areas. Furthermore, the three methods described are intended as indicators of the state-of-the-art in water erosion prediction. The procedures herein do not account for gully erosion, snowmelt erosion, wind erosion, freeze-thaw erosion or extensive flooding

  16. Testing and prediction of erosion-corrosion for corrosion resistant alloys used in the oil and gas production industry

    Science.gov (United States)

    Rincon, Hernan E.

    The corrosion behavior of CRAs has been thoroughly investigated and documented in the public literature by many researchers; however, little work has been done to investigate erosion-corrosion of such alloys. When sand particles are entrained in the flow, the degradation mechanism is different from that observed for sand-free corrosive environment. There is a need in the oil and gas industry to define safe service limits for utilization of such materials. The effects of flow conditions, sand rate, pH and temperature on the erosion-corrosion of CRAs were widely studied. An extensive experimental work was conducted using scratch tests and flow loop tests using several experimental techniques. At high erosivity conditions, a synergistic effect between erosion and corrosion was observed. Under the high sand rate conditions tested, erosivity is severe enough to damage the passive layer protecting the CRA thereby enhancing the corrosion rate. In most cases there is likely a competition between the rates of protective film removal due to mechanical erosion and protective film healing. Synergism occurs for each of the three alloys examined (13Cr and Super13Cr and 22Cr); however, the degree of synergism is quite different for the three alloys and may not be significant for 22Cr for field conditions where erosivities are typically much lower that those occurring in the small bore loop used in this research. Predictions of the corrosion component of erosion-corrosion based on scratch test data compared reasonably well to test results from flow loops for the three CRAs at high erosivity conditions. Second order behavior appears to be an appropriate and useful model for representing the repassivation process of CRAs. A framework for a procedure to predict penetration rates for erosion-corrosion conditions was developed based on the second order model behavior observed for the re-healing process of the passive film of CRAs and on computational fluid dynamics (CFD) simulations

  17. Particle Impact Erosion. Volume 4. User’s Manual Erosion Prediction Procedure for Rocket Nozzle Expansion Region

    Science.gov (United States)

    1983-05-01

    empirical erosion model, with use of the debris-layer model optional. 1.1 INTERFACE WITH ISPP ISPP is a collection of computer codes designed to calculate...expansion with the ODK code, 4. A two-dimensional, two-phase nozzle expansion with the TD2P code, 5. A turbulent boundary layer solution along the...INPUT THERMODYNAMIC DATA FOR TEMPERATURESBELOW 300°K OIF NEEDED) NO A• 11 READ SSP NAMELIST (ODE. BAL. ODK . TD2P. TEL. NOZZLE GEOMETRY) PROfLM 2

  18. Changes in wind erosion over a 25-year restoration chronosequence on the south edge of the Tengger Desert, China: implications for preventing desertification.

    Science.gov (United States)

    Ma, Quanlin; Fehmi, Jeffrey S; Zhang, Dekui; Fan, Baoli; Chen, Fang

    2017-08-23

    Wind erosion is a primary cause of desertification as well as being a serious ecological problem in arid and semi-arid areas across the world. To determine mechanisms for restoring desertified lands, an unrestored shifting sand dune and three formerly shifting sand dunes (desertified lands) that had been enclosed and afforested for 5, 15, and 25 years were selected for evaluation on the south edge of the Tengger Desert, China. Based on sampling heights between 0.2 and 3 m, the critical threshold average wind speed was 6.5 m s -1 at 2 m where the sand transport rate was reduced from 285.9 kg m -2  h -1 on the unrestored dunes to 9.1 and 1.8 kg m -2  h -1 on the sites afforested and enclosed for 5 and 15 years, respectively. The percentage of wind eroded area was reduced from 99.9% on the unrestored dune to 94.5, 9.0, and 0.5% on the sites afforested and enclosed for 5, 15, and 25 years, respectively. Wind erosion was effectively reduced after 15 years. Although there were different driving factors for wind erosion mitigation on the different restoration stages, an increase in the vegetation cover, surface roughness, soil shear strength, soil clay content, organic matter, and reduction in the near-surface wind speed were the primary variables associated with the restoration chronosequence. We conclude that reducing the wind speed and developing a biological crust through vegetation restoration were the critical components for restoration of desertified land.

  19. KwaZulu-Natal coastal erosion events of 2006/2007 and 2011: A predictive tool?

    OpenAIRE

    Alan Smith; Lisa A. Guastella; Andrew A. Mather; Simon C. Bundy; Ivan D. Haigh

    2013-01-01

    Severe coastal erosion occurred along the KwaZulu-Natal coastline between mid-May and November 2011. Analysis of this erosion event and comparison with previous coastal erosion events in 2006/2007 offered the opportunity to extend the understanding of the time and place of coastal erosion strikes. The swells that drove the erosion hotspots of the 2011 erosion season were relatively low (significant wave heights were between 2 m and 4.5 m) but of long duration. Although swell height was import...

  20. Measurement of erosion: Is it possible?

    NARCIS (Netherlands)

    Stroosnijder, L.

    2005-01-01

    Reasons for erosion measurements are: (1) to determine the environmental impact of erosion and conservation practices, (2) scientific erosion research; (3) development and evaluation of erosion control technology; (4) development of erosion prediction technology and (5) allocation of conservation

  1. Statistical downscaling of historical monthly mean winds over a coastal region of complex terrain. II. Predicting wind components

    Energy Technology Data Exchange (ETDEWEB)

    Kamp, Derek van der [University of Victoria, Pacific Climate Impacts Consortium, Victoria, BC (Canada); University of Victoria, School of Earth and Ocean Sciences, Victoria, BC (Canada); Curry, Charles L. [Environment Canada University of Victoria, Canadian Centre for Climate Modelling and Analysis, Victoria, BC (Canada); University of Victoria, School of Earth and Ocean Sciences, Victoria, BC (Canada); Monahan, Adam H. [University of Victoria, School of Earth and Ocean Sciences, Victoria, BC (Canada)

    2012-04-15

    A regression-based downscaling technique was applied to monthly mean surface wind observations from stations throughout western Canada as well as from buoys in the Northeast Pacific Ocean over the period 1979-2006. A predictor set was developed from principal component analysis of the three wind components at 500 hPa and mean sea-level pressure taken from the NCEP Reanalysis II. Building on the results of a companion paper, Curry et al. (Clim Dyn 2011), the downscaling was applied to both wind speed and wind components, in an effort to evaluate the utility of each type of predictand. Cross-validated prediction skill varied strongly with season, with autumn and summer displaying the highest and lowest skill, respectively. In most cases wind components were predicted with better skill than wind speeds. The predictive ability of wind components was found to be strongly related to their orientation. Wind components with the best predictions were often oriented along topographically significant features such as constricted valleys, mountain ranges or ocean channels. This influence of directionality on predictive ability is most prominent during autumn and winter at inland sites with complex topography. Stations in regions with relatively flat terrain (where topographic steering is minimal) exhibit inter-station consistencies including region-wide seasonal shifts in the direction of the best predicted wind component. The conclusion that wind components can be skillfully predicted only over a limited range of directions at most stations limits the scope of statistically downscaled wind speed predictions. It seems likely that such limitations apply to other regions of complex terrain as well. (orig.)

  2. Tidal influence on offshore wind fields and resource predictions[Efficient Development of Offshore Windfarms

    Energy Technology Data Exchange (ETDEWEB)

    Khan, D. [Entec UK Ltd., Doherty Innovation Centre, Penicuik (United Kingdom); Infield, D. [Loughborough Univ., Centre for Renewable Energy Systems Tecnology, Loughborough (United Kingdom)

    2002-03-01

    The rise and fall of the sea surface due to tides effectively moves an offshore wind turbine hub through the wind shear profile. This effect is quantified using measured data from 3 offshore UK sites. Statistical evidence of the influence of tide on mean wind speed and turbulence is presented. The implications of this effect for predicting offshore wind resource are outlined. (au)

  3. Model predictive control of a wind turbine modelled in Simpack

    International Nuclear Information System (INIS)

    Jassmann, U; Matzke, D; Reiter, M; Abel, D; Berroth, J; Schelenz, R; Jacobs, G

    2014-01-01

    Wind turbines (WT) are steadily growing in size to increase their power production, which also causes increasing loads acting on the turbine's components. At the same time large structures, such as the blades and the tower get more flexible. To minimize this impact, the classical control loops for keeping the power production in an optimum state are more and more extended by load alleviation strategies. These additional control loops can be unified by a multiple-input multiple-output (MIMO) controller to achieve better balancing of tuning parameters. An example for MIMO control, which has been paid more attention to recently by wind industry, is Model Predictive Control (MPC). In a MPC framework a simplified model of the WT is used to predict its controlled outputs. Based on a user-defined cost function an online optimization calculates the optimal control sequence. Thereby MPC can intrinsically incorporate constraints e.g. of actuators. Turbine models used for calculation within the MPC are typically simplified. For testing and verification usually multi body simulations, such as FAST, BLADED or FLEX5 are used to model system dynamics, but they are still limited in the number of degrees of freedom (DOF). Detailed information about load distribution (e.g. inside the gearbox) cannot be provided by such models. In this paper a Model Predictive Controller is presented and tested in a co-simulation with SlMPACK, a multi body system (MBS) simulation framework used for detailed load analysis. The analysis are performed on the basis of the IME6.0 MBS WT model, described in this paper. It is based on the rotor of the NREL 5MW WT and consists of a detailed representation of the drive train. This takes into account a flexible main shaft and its main bearings with a planetary gearbox, where all components are modelled flexible, as well as a supporting flexible main frame. The wind loads are simulated using the NREL AERODYN v13 code which has been implemented as a routine

  4. Model predictive control of a wind turbine modelled in Simpack

    Science.gov (United States)

    Jassmann, U.; Berroth, J.; Matzke, D.; Schelenz, R.; Reiter, M.; Jacobs, G.; Abel, D.

    2014-06-01

    Wind turbines (WT) are steadily growing in size to increase their power production, which also causes increasing loads acting on the turbine's components. At the same time large structures, such as the blades and the tower get more flexible. To minimize this impact, the classical control loops for keeping the power production in an optimum state are more and more extended by load alleviation strategies. These additional control loops can be unified by a multiple-input multiple-output (MIMO) controller to achieve better balancing of tuning parameters. An example for MIMO control, which has been paid more attention to recently by wind industry, is Model Predictive Control (MPC). In a MPC framework a simplified model of the WT is used to predict its controlled outputs. Based on a user-defined cost function an online optimization calculates the optimal control sequence. Thereby MPC can intrinsically incorporate constraints e.g. of actuators. Turbine models used for calculation within the MPC are typically simplified. For testing and verification usually multi body simulations, such as FAST, BLADED or FLEX5 are used to model system dynamics, but they are still limited in the number of degrees of freedom (DOF). Detailed information about load distribution (e.g. inside the gearbox) cannot be provided by such models. In this paper a Model Predictive Controller is presented and tested in a co-simulation with SlMPACK, a multi body system (MBS) simulation framework used for detailed load analysis. The analysis are performed on the basis of the IME6.0 MBS WT model, described in this paper. It is based on the rotor of the NREL 5MW WT and consists of a detailed representation of the drive train. This takes into account a flexible main shaft and its main bearings with a planetary gearbox, where all components are modelled flexible, as well as a supporting flexible main frame. The wind loads are simulated using the NREL AERODYN v13 code which has been implemented as a routine to

  5. A large source of dust missing in Particulate Matter emission inventories? Wind erosion of post-fire landscapes

    Directory of Open Access Journals (Sweden)

    N.S. Wagenbrenner

    2017-02-01

    Full Text Available Wind erosion of soils burned by wildfire contributes substantial particulate matter (PM in the form of dust to the atmosphere, but the magnitude of this dust source is largely unknown. It is important to accurately quantify dust emissions because they can impact human health, degrade visibility, exacerbate dust-on-snow issues (including snowmelt timing, snow chemistry, and avalanche danger, and affect ecological and biogeochemical cycles, precipitation regimes, and the Earth’s radiation budget. We used a novel modeling approach in which local-scale winds were used to drive a high-resolution dust emission model parameterized for burned soils to provide a first estimate of post-fire PM emissions. The dust emission model was parameterized with dust flux measurements from a 2010 fire scar. Here we present a case study to demonstrate the ability of the modeling framework to capture the onset and dynamics of a post-fire dust event and then use the modeling framework to estimate PM emissions from burn scars left by wildfires in U.S. western sagebrush landscapes during 2012. Modeled emissions from 1.2 million ha of burned soil totaled 32.1 Tg (11.7–352 Tg of dust as PM10 and 12.8 Tg (4.68–141 Tg as PM2.5. Despite the relatively large uncertainties in these estimates and a number of underlying assumptions, these first estimates of annual post-fire dust emissions suggest that post-fire PM emissions could substantially increase current annual PM estimates in the U.S. National Emissions Inventory during high fire activity years. Given the potential for post-fire scars to be a large source of PM, further on-site PM flux measurements are needed to improve emission parameterizations and constrain these first estimates.

  6. Evaluating water erosion prediction project model using Cesium-137-derived spatial soil redistribution data

    Science.gov (United States)

    The lack of spatial soil erosion data has been a major constraint on the refinement and application of physically based erosion models. Spatially distributed models can only be thoroughly validated with distributed erosion data. The fallout cesium-137 has been widely used to generate spatial soil re...

  7. Rain erosion of wind turbine blade coatings using discrete water jets: Effects of water cushioning, substrate geometry, impact distance, and coating properties

    DEFF Research Database (Denmark)

    Zhang, Shizhong; Dam-Johansen, Kim; Bernad, Pablo L.

    2015-01-01

    Rapid and reliable rain erosion screening of blade coatings for wind turbines is a strong need in the coatings industry. One possibility in this direction is the use of discrete water jets, where so-called jet slugs are impacted on a coating surface. Previous investigations have mapped...... the influence of water jet slug velocity and impact frequency. In the present work, the effects on coating erosion of water cushioning, substrate curvature, and water nozzle-coating distance were explored. The investigations showed that in some cases water cushioning (the presence of a liquid film...... on the coating surface prior to impact) influences the erosion. Contrary to this, substrate curvature and the water nozzle-coating distance (

  8. [Responses of soil fauna to environment degeneration in the process of wind erosion desertification of Hulunbeir steppe].

    Science.gov (United States)

    Lü, Shi-Hai; Lu, Xin-Shi; Gao, Ji-Xi

    2007-09-01

    To reveal the relationships between soil fauna and soil environmental factors in the process of steppe desertification, field survey combined with laboratory analysis was made to study the community structure, population density and biodiversity of soil fauna, and their relationships with the changes of soil organic matter, hydrolysable nitrogen, available phosphorus and moisture contents and soil pH at different stages of desertification of Hulunbeir steppe. The soil faunal specimens collected belonged to 4 phyla, 6 classes and 12 orders. Nematoda was the only dominant group of medium- and small-sized soil fauna, occupying 94.3% of the total, while Coleoptera and Hemiptera were the dominant groups of large-sized soil fauna, with the amount of 79.7%. The group amount, population density, diversity, and evenness of soil fauna had an obvious decreasing trend with the aggravation of steppe desertification. At serious stage of desertification, soil fauna vanished completely. The population density of soil fauna in 0-20 cm soil layer had significant linear correlations with soil nutrients and moisture contents, soil pH, and litter mass, indicating that soil fauna had stronger sensibility to the changes of soil environmental factors in the process of wind erosion desertification of Hulunbeir steppe.

  9. Performance and wake predictions of HAWTs in wind farms

    Energy Technology Data Exchange (ETDEWEB)

    Leclerc, C.; Masson, C.; Paraschivoiu, I. [Ecole Polytechnique, Montreal (Canada)

    1997-12-31

    The present contribution proposes and describes a promising way towards performance prediction of an arbitrary array of turbines. It is based on the solution of the time-averaged, steady-state, incompressible Navier-Stokes equations with an appropriate turbulence closure model. The turbines are represented by distributions of momentum sources in the Navier-Stokes equations. In this paper, the applicability and viability of the proposed methodology is demonstrated using an axisymmetric implementation. The k-{epsilon} model has been chosen for the closure of the time-averaged, turbulent flow equations and the properties of the incident flow correspond to those of a neutral atmospheric boundary layer. The proposed mathematical model is solved using a Control-Volume Finite Element Method (CVFEM). Detailed results have been obtained using the proposed method for an isolated wind turbine and for two turbines one behind another. In the case of an isolated turbine, accurate wake velocity deficit predictions are obtained and an increase in power due to atmospheric turbulence is found in agreement with measurements. In the case of two turbines, the proposed methodology provides an appropriate modelling of the wind-turbine wake and a realistic prediction of the performance degradation of the downstream turbine.

  10. PREDICTION OF POWER GENERATION OF SMALL SCALE VERTICAL AXIS WIND TURBINE USING FUZZY LOGIC

    Directory of Open Access Journals (Sweden)

    Altab Hossain

    2009-01-01

    Full Text Available Renewable energy from the wind turbine has been focused for the alternative source of power generation due to the following advances of the of the wind turbine. Firstly, the wind turbine is highly efficient and eco-friendly. Secondly, the turbine has the ability to response for the changeable power generation based on the wind velocity and structural framework. However, the competitive efficiency of the wind turbine is necessary to successfully alternate the conventional power sources. The most relevant factor which affects the overall efficiency of the wind turbine is the wind velocity and the relative turbine dimensions. Artificial intelligence systems are widely used technology that can learn from examples and are able to deal with non-linear problems. Compared with traditional approach, fuzzy logic approach is more efficient for the representation, manipulation and utilization. Therefore, the primary purpose of this work was to investigate the relationship between wind turbine power generation and wind velocity, and to illustrate how fuzzy expert system might play an important role in prediction of wind turbine power generation. The main purpose of the measurement over the small scaled prototype vertical axis wind turbine for the wind velocity is to predict the performance of full scaled H-type vertical axis wind turbine. Prediction of power generation at the different wind velocities has been tested at the Thermal Laboratory of Faculty of Engineering, Universiti Industri Selangor (UNISEL and results concerning the daily prediction have been obtained.

  11. PREDICTION OF POWER GENERATION OF SMALL SCALE VERTICAL AXIS WIND TURBINE USING FUZZY LOGIC

    Directory of Open Access Journals (Sweden)

    Altab Md. Hossain

    2009-12-01

    Full Text Available Renewable energy from the wind turbine has been focused for the alternative source of power generation due to the following advances of the of the wind turbine. Firstly, the wind turbine is highly efficient and eco-friendly. Secondly, the turbine has the ability to response for the changeable power generation based on the wind velocity and structural framework. However, the competitive efficiency of the wind turbine is necessary to successfully alternate the conventional power sources. The most relevant factor which affects the overall efficiency of the wind turbine is the wind velocity and the relative turbine dimensions. Artificial intelligence systems are widely used technology that can learn from examples and are able to deal with non-linear problems. Compared with traditional approach, fuzzy logic approach is more efficient for the representation, manipulation and utilization. Therefore, the primary purpose of this work was to investigate the relationship between wind turbine power generation and wind velocity, and to illustrate how fuzzy expert system might play an important role in prediction of wind turbine power generation. The main purpose of the measurement over the small scaled prototype vertical axis wind turbine for the wind velocity is to predict the performance of full scaled H-type vertical axis wind turbine. Prediction of power generation at the different wind velocities has been tested at the Thermal Laboratory of Faculty of Engineering, Universiti Industri Selangor (UNISEL and results concerning the daily prediction have been obtained.

  12. Predicting wind shear effects: A study of Minnesota wind data collected at heights up to 70 meters

    Energy Technology Data Exchange (ETDEWEB)

    Artig, R. [Minnesota Dept. of Public Service, St. Paul, MN (United States)

    1997-12-31

    The Minnesota Department of Public Service (DPS) collects wind data at carefully selected sites around the state and analyzes the data to determine Minnesota`s wind power potential. DPS recently installed advanced new monitoring equipment at these sites and began to collect wind data at 30, 50, and 70 meters above ground level, with two anemometers at each level. Previously, the Department had not collected data at heights above ground level higher than 30 meters. DPS also, with the U.S. Department of Energy (DOE), installed four sophisticated monitoring sites as part of a Tall Tower Wind Shear Study that is assessing the effects of wind shear on wind power potential. At these sites, wind data are being collected at the 10, 30, 40, 50, 60, and 70 meter heights. This paper presents the preliminary results of the analysis of wind data from all sites. These preliminary results indicate that the traditional 1/7 power law does not effectively predict wind shear in Minnesota, and the result is an underestimation of Minnesota`s wind power potential at higher heights. Using a power factor of 1/5 or 1/4 may be more accurate and provide sound justification for installing wind turbines on taller towers in Minnesota.

  13. Usability and Functional Enhancements to an Online Interface for Predicting Post Fire Erosion (WEPP-PEP)

    Science.gov (United States)

    Lew, Roger; Dobre, Mariana; Elliot, William; Robichaud, Pete; Brooks, Erin; Frankenberger, Jim

    2017-04-01

    There is an increased interest in the United States to use soil burn severity maps in watershed-scale hydrologic models to estimate post-fire sediment erosion from burned areas. This information is needed by stakeholders in order to concentrate their pre- or post-fire management efforts in ecologically sensitive areas to decrease the probability of post-fire sediment delivery. But these tools traditionally have been time consuming and difficult to use by managers because input datasets must be obtained and correctly processed for valid results. The Water Erosion Prediction Project (WEPP) has previously been developed as an online and easy-to-use interface to help land managers with running simulations without any knowledge of computer programming or hydrologic modeling. The interface automates the acquisition of DEM, climate, soils, and landcover data, and also automates channel and hillslope delineation for the users. The backend is built with Mapserver, GDAL, PHP, C++, Python while the front end uses OpenLayers, and, of course, JavaScript. The existing WEPP online interface was enhanced to provide better usability to stakeholders in United States (Forest Service, BLM, USDA) as well as to provide enhanced functionality for managing both pre-fire and post-fire treatments. Previously, only site administrators could add burn severity maps. The interface now allows users to create accounts to upload and share FlamMap prediction maps, differenced Normalized Burned Ratio (dNBR), or Burned Area Reflectance Classification (BARC) maps. All maps are loaded into a sortable catalog so users can quickly find their area of interest. Once loaded, the interface has been modified to support running comparisons between baseline condition with "no burn" and with a burn severity classification map. The interface has also been enhanced to allow users to conduct single storm analyses to examine, for example, how much soil loss would result after a 100-year storm. An OpenLayers map

  14. A new approach to very short term wind speed prediction using k-nearest neighbor classification

    International Nuclear Information System (INIS)

    Yesilbudak, Mehmet; Sagiroglu, Seref; Colak, Ilhami

    2013-01-01

    Highlights: ► Wind speed parameter was predicted in an n-tupled inputs using k-NN classification. ► The effects of input parameters, nearest neighbors and distance metrics were analyzed. ► Many useful and reasonable inferences were uncovered using the developed model. - Abstract: Wind energy is an inexhaustible energy source and wind power production has been growing rapidly in recent years. However, wind power has a non-schedulable nature due to wind speed variations. Hence, wind speed prediction is an indispensable requirement for power system operators. This paper predicts wind speed parameter in an n-tupled inputs using k-nearest neighbor (k-NN) classification and analyzes the effects of input parameters, nearest neighbors and distance metrics on wind speed prediction. The k-NN classification model was developed using the object oriented programming techniques and includes Manhattan and Minkowski distance metrics except from Euclidean distance metric on the contrary of literature. The k-NN classification model which uses wind direction, air temperature, atmospheric pressure and relative humidity parameters in a 4-tupled space achieved the best wind speed prediction for k = 5 in the Manhattan distance metric. Differently, the k-NN classification model which uses wind direction, air temperature and atmospheric pressure parameters in a 3-tupled inputs gave the worst wind speed prediction for k = 1 in the Minkowski distance metric

  15. Watershed-scale evaluation of the Water Erosion Prediction Project (WEPP) model in the Lake Tahoe basin

    Science.gov (United States)

    Erin S. Brooks; Mariana Dobre; William J. Elliot; Joan Q. Wu; Jan Boll

    2016-01-01

    Forest managers need methods to evaluate the impacts of management at the watershed scale. The Water Erosion Prediction Project (WEPP) has the ability to model disturbed forested hillslopes, but has difficulty addressing some of the critical processes that are important at a watershed scale, including baseflow and water yield. In order to apply WEPP to...

  16. Benefits for wind energy in electricity markets from using short term wind power prediction tools: a simulation study

    International Nuclear Information System (INIS)

    Usaola, J.; Ravelo, O.; Gonzalez, G.; Soto, F.; Davila, M.C.; Diaz-Guerra, B.

    2004-01-01

    One of the characteristics of wind energy, from the grid point of view, is its non-dispatchability, i.e. generation cannot be ordered, hence integration in electrical networks may be difficult. Short-term wind power prediction-tools could make this integration easier, either by their use by the grid System Operator, or by promoting the participation of wind farms in the electricity markets and using prediction tools to make their bids in the market. In this paper, the importance of a short-term wind power-prediction tool for the participation of wind energy systems in electricity markets is studied. Simulations, according to the current Spanish market rules, have been performed to the production of different wind farms, with different degrees of accuracy in the prediction tool. It may be concluded that income from participation in electricity markets is increased using a short-term wind power prediction-tool of average accuracy. This both marginally increases income and also reduces the impact on system operation with the improved forecasts. (author)

  17. Repetitive model predictive approach to individual pitch control of wind turbines

    DEFF Research Database (Denmark)

    Adegas, Fabiano Daher; Stoustrup, Jakob; Odgaard, Peter Fogh

    2011-01-01

    prediction. As a consequence, individual pitch feed-forward control action is generated by the controller, taking ”future” wind disturbance into account. Information about the estimated wind spatial distribution one blade experience can be used in the prediction model to better control the next passing blade......Wind turbines are inherently exposed to nonuniform wind fields with of wind shear, tower shadow, and possible wake contributions. Asymmetrical aerodynamic rotor loads are a consequence of such periodic, repetitive wind disturbances experienced by the blades. A controller may estimate and use...... this peculiar disturbance pattern to better attenuate loads and regulate power by controlling the blade pitch angles individually. A novel model predictive (MPC) approach for individual pitch control of wind turbines is proposed in this paper. A repetitive wind disturbance model is incorporated into the MPC...

  18. Oxygen isotopic ratios of quartz from wind-erosive soils of southwestern United States in relation to aerosol dust

    Energy Technology Data Exchange (ETDEWEB)

    Sridhar, K.; Jackson, M.L.; Clayton, R.N.; Gillette, D.A.; Hawley, J.W.

    1978-01-01

    The oxygen isotopic ratios (expressed as parts per thousand relative to mean ocean water, SMOW, delta/sup 18/O) of the quartz from 13 soils undergoing much wind erosion during the study period of 1972-1975 in four southwestern states and from comparison areas were determined. The delta/sup 18/O for quartz from eight Texas (TX) and Arizona (AZ) soils range from 13.0 to 15.9 /sup 0///sub 00/. The quartz of the sands and silts coarser than 20 ..mu..m from three of the soils had delta/sup 18/O values ranging from 13.1 to 15.1 /sup 0///sub 00/, characteristic of an ultimate igneous-metamorphic origin. The delta/sup 18/O values increase greatly with decreasing particle size of quartz from three soils ranging from loamy fine sand to loam to clay in texture. The delta/sup 18/O of the 1-10 ..mu..m quartz fraction (aerosol size) ranged from 19.2 to 20.2 /sup 0///sub 00/ (19.55 +- 0.28 /sup 0///sub 00/; +- sigma) for the thirteen soils most affected by dust storms. The oxygen isotopic ratios of 1-10 ..mu..m quartz from three Hawaiian soils and two sediments from Lake Waiau occurring at 3,970 m altitude on the Mauna Kea summit on the Island of Hawaii give a delta/sup 18/O mean of 18.3 +- 0.2 /sup 0///sub 00/.

  19. How Many Model Evaluations Are Required To Predict The AEP Of A Wind Power Plant?

    DEFF Research Database (Denmark)

    Murcia Leon, Juan Pablo; Réthoré, Pierre-Elouan; Natarajan, Anand

    2015-01-01

    (AEP) predictions expensive. The objective of the present paper is to minimize the number of model evaluations required to capture the wind power plant's AEP using stationary wind farm flow models. Polynomial chaos techniques are proposed based on arbitrary Weibull distributed wind speed and Von Misses...... distributed wind direction. The correlation between wind direction and wind speed are captured by defining Weibull-parameters as functions of wind direction. In order to evaluate the accuracy of these methods the expectation and variance of the wind farm power distributions are compared against...... the traditional binning method with trapezoidal and Simpson's integration rules. The wind farm flow model used in this study is the semi-empirical wake model developed by Larsen [1]. Three test cases are studied: a single turbine, a simple and a real offshore wind power plant. A reduced number of model...

  20. Wind Speed Prediction with Wavelet Time Series Based on Lorenz Disturbance

    Directory of Open Access Journals (Sweden)

    ZHANG, Y.

    2017-08-01

    Full Text Available Due to the sustainable and pollution-free characteristics, wind energy has been one of the fastest growing renewable energy sources. However, the intermittent and random fluctuation of wind speed presents many challenges for reliable wind power integration and normal operation of wind farm. Accurate wind speed prediction is the key to ensure the safe operation of power system and to develop wind energy resources. Therefore, this paper has presented a wavelet time series wind speed prediction model based on Lorenz disturbance. Therefore, in this paper, combined with the atmospheric dynamical system, a wavelet-time series improved wind speed prediction model based on Lorenz disturbance is proposed and the wind turbines of different climate types in Spain and China are used to simulate the disturbances of Lorenz equations with different initial values. The prediction results show that the improved model can effectively correct the preliminary prediction of wind speed, improving the prediction. In a word, the research work in this paper will be helpful to arrange the electric power dispatching plan and ensure the normal operation of the wind farm.

  1. Effects of Long-term Conservation Tillage on Soil Nutrients in Sloping Fields in Regions Characterized by Water and Wind Erosion

    Science.gov (United States)

    Tan, Chunjian; Cao, Xue; Yuan, Shuai; Wang, Weiyu; Feng, Yongzhong; Qiao, Bo

    2015-12-01

    Conservation tillage is commonly used in regions affected by water and wind erosion. To understand the effects of conservation tillage on soil nutrients and yield, a long-term experiment was set up in a region affected by water and wind erosion on the Loess Plateau. The treatments used were traditional tillage (CK), no tillage (NT), straw mulching (SM), plastic-film mulching (PM), ridging and plastic-film mulching (RPM) and intercropping (In). Our results demonstrate that the available nutrients in soils subjected to non-traditional tillage treatments decreased during the first several years and then remained stable over the last several years of the experiment. The soil organic matter and total nitrogen content increased gradually over 6 years in all treatments except CK. The nutrient content of soils subjected to conservative tillage methods, such as NT and SM, were significantly higher than those in soils under the CK treatment. Straw mulching and film mulching effectively reduced an observed decrease in soybean yield. Over the final 6 years of the experiment, soybean yields followed the trend RPM > PM > SM > NT > CK > In. This trend has implications for controlling soil erosion and preventing non-point source pollution in sloping fields by sacrificing some food production.

  2. Optimal day-ahead wind-thermal unit commitment considering statistical and predicted features of wind speeds

    International Nuclear Information System (INIS)

    Sun, Yanan; Dong, Jizhe; Ding, Lijuan

    2017-01-01

    Highlights: • A day–ahead wind–thermal unit commitment model is presented. • Wind speed transfer matrix is formed to depict the sequential wind features. • Spinning reserve setting considering wind power accuracy and variation is proposed. • Verified study is performed to check the correctness of the program. - Abstract: The increasing penetration of intermittent wind power affects the secure operation of power systems and leads to a requirement of robust and economic generation scheduling. This paper presents an optimal day–ahead wind–thermal generation scheduling method that considers the statistical and predicted features of wind speeds. In this method, the statistical analysis of historical wind data, which represents the local wind regime, is first implemented. Then, according to the statistical results and the predicted wind power, the spinning reserve requirements for the scheduling period are calculated. Based on the calculated spinning reserve requirements, the wind–thermal generation scheduling is finally conducted. To validate the program, a verified study is performed on a test system. Then, numerical studies to demonstrate the effectiveness of the proposed method are conducted.

  3. Automated lake-wide erosion predictions and economic damage calculations upstream of the Moses-Saunders power dam

    International Nuclear Information System (INIS)

    Zuzek, P.; Baird, W.F.; International Joint Commission, Ottawa, ON

    2008-01-01

    This presentation discussed an automated flood and erosion prediction system designed for the upstream sections of the Moses-Saunders power dam. The system included a wave prediction component along with 3-D maps, hourly run-ups, geographic information system (GIS) tools and a hazard analysis tool. Parcel, reach, township, and county databases were used to populate the system. The prediction system was used to develop detailed study sites of shore units in the study area. Shoreline classes included sand and cohesive buffs, low banks, coarse beaches, and cobble or boulder lags. Time series plots for Lake Ontario water and wave levels were presented. Great Lakes ice cover data were also included in the system as well as erosion predictions from 1961 to 1995. The system was also used to develop bluff recession equations and cumulative recession analyses for different regulation plans. Cumulative bluff recession and protection requirements were outlined. Screenshots of the flood and erosion prediction system interface were also included. tabs., figs

  4. On Practical tuning of Model Uncertainty in Wind Turbine Model Predictive Control

    DEFF Research Database (Denmark)

    Odgaard, Peter Fogh; Hovgaard, Tobias

    2015-01-01

    Model predictive control (MPC) has in previous works been applied on wind turbines with promising results. These results apply linear MPC, i.e., linear models linearized at different operational points depending on the wind speed. The linearized models are derived from a nonlinear first principles...... model of a wind turbine. In this paper, we investigate the impact of this approach on the performance of a wind turbine. In particular, we focus on the most non-linear operational ranges of a wind turbine. The MPC controller is designed for, tested, and evaluated at an industrial high fidelity wind...

  5. Soil Erosion Prediction Using Morgan-Morgan-Finney Model in a GIS Environment in Northern Ethiopia Catchment

    Directory of Open Access Journals (Sweden)

    Gebreyesus Brhane Tesfahunegn

    2014-01-01

    Full Text Available Even though scientific information on spatial distribution of hydrophysical parameters is critical for understanding erosion processes and designing suitable technologies, little is known in Geographical Information System (GIS application in developing spatial hydrophysical data inputs and their application in Morgan-Morgan-Finney (MMF erosion model. This study was aimed to derive spatial distribution of hydrophysical parameters and apply them in the Morgan-Morgan-Finney (MMF model for estimating soil erosion in the Mai-Negus catchment, northern Ethiopia. Major data input for the model include climate, topography, land use, and soil data. This study demonstrated using MMF model that the rate of soil detachment varied from 170 t ha−1 y−1, whereas the soil transport capacity of overland flow (TC ranged from 5 t ha−1 y−1 to >42 t ha−1 y−1. The average soil loss estimated by TC using MMF model at catchment level was 26 t ha−1 y−1. In most parts of the catchment (>80%, the model predicted soil loss rates higher than the maximum tolerable rate (18 t ha−1 y−1 estimated for Ethiopia. Hence, introducing appropriate interventions based on the erosion severity predicted by MMF model in the catchment is crucial for sustainable natural resources management.

  6. Wind Turbine Generator Efficiency Based on Powertrain Combination and Annual Power Generation Prediction

    Directory of Open Access Journals (Sweden)

    Dongmyung Kim

    2018-05-01

    Full Text Available Wind turbine generators are eco-friendly generators that produce electric energy using wind energy. In this study, wind turbine generator efficiency is examined using a powertrain combination and annual power generation prediction, by employing an analysis model. Performance testing was conducted in order to analyze the efficiency of a hydraulic pump and a motor, which are key components, and so as to verify the analysis model. The annual wind speed occurrence frequency for the expected installation areas was used to predict the annual power generation of the wind turbine generators. It was found that the parallel combination of the induction motors exhibited a higher efficiency when the wind speed was low and the serial combination showed higher efficiency when wind speed was high. The results of predicting the annual power generation considering the regional characteristics showed that the power generation was the highest when the hydraulic motors were designed in parallel and the induction motors were designed in series.

  7. Development of Erosive Burning Models for CFD Predictions of Solid Rocket Motor Internal Environments

    Science.gov (United States)

    Wang, Qun-Zhen

    2003-01-01

    Four erosive burning models, equations (11) to (14). are developed in this work by using a power law relationship to correlate (1) the erosive burning ratio and the local velocity gradient at propellant surfaces; (2) the erosive burning ratio and the velocity gradient divided by centerline velocity; (3) the erosive burning difference and the local velocity gradient at propellant surfaces; and (4) the erosive burning difference and the velocity gradient divided by centerline velocity. These models depend on the local velocity gradient at the propellant surface (or the velocity gradient divided by centerline velocity) only and, unlike other empirical models, are independent of the motor size. It was argued that, since the erosive burning is a local phenomenon occurring near the surface of the solid propellant, the erosive burning ratio should be independent of the bore diameter if it is correlated with some local flow parameters such as the velocity gradient at the propellant surface. This seems to be true considering the good results obtained by applying these models, which are developed from the small size 5 inch CP tandem motor testing, to CFD simulations of much bigger motors.

  8. Crust behavior and erosion rate prediction of EPR sacrificial material impinged by core melt jet

    Energy Technology Data Exchange (ETDEWEB)

    Li, Gen; Liu, Ming, E-mail: ming.liu@mail.xjtu.edu.cn; Wang, Jinshi; Chong, Daotong; Yan, Junjie

    2017-04-01

    Highlights: • A numerical code was developed to analyze melt jet-concrete interaction in the frame of MPS method. • Crust and ablated concrete layer at UO{sub 2}-ZrO{sub 2} melt and concrete interface periodically developed and collapsed. • Concrete surface temperature fluctuated around a low temperature and ablation temperature. • Concrete erosion by Fe-Zr melt jet was significantly faster than that by UO{sub 2}-ZrO{sub 2} melt jet. - Abstract: Sacrificial material is a special ferro-siliceous concrete, designed in the ex-vessel core melt stabilization system of European Pressurized water Reactor (EPR). Given a localized break of RPV lower head, the melt directly impinges onto the dry concrete in form of compact jet. The concrete erosion behavior influences the failure of melt plug, and further affects melt spreading. In this study, a numerical code was developed in the frame of Moving Particle Semi-implicit (MPS) method, to analyze the crust behavior and erosion rate of sacrificial concrete, impinged by prototypic melt jet. In validation of numerical modeling, the time-dependent erosion depth and erosion configuration matched well with the experimental data. Sensitivity study of sacrificial concrete erosion indicates that the crust and ablated concrete layer presented at UO{sub 2}-ZrO{sub 2} melt and concrete interface, whereas no crust could be found in the interaction of Fe-Zr melt with concrete. The crust went through stabilization-fracture-reformation periodic process, accompanied with accumulating and collapsing of molten concrete layer. The concrete surface temperature fluctuated around a low temperature and ablation temperature. It increased as the concrete surface layer was heated to melting, and dropped down when the cold concrete was revealed. The erosion progression was fast in the conditions of small jet diameter and large concrete inclination angle, and it was significantly faster in the erosion by metallic melt jet than by oxidic melt jet.

  9. Short-term wind power prediction based on LSSVM–GSA model

    International Nuclear Information System (INIS)

    Yuan, Xiaohui; Chen, Chen; Yuan, Yanbin; Huang, Yuehua; Tan, Qingxiong

    2015-01-01

    Highlights: • A hybrid model is developed for short-term wind power prediction. • The model is based on LSSVM and gravitational search algorithm. • Gravitational search algorithm is used to optimize parameters of LSSVM. • Effect of different kernel function of LSSVM on wind power prediction is discussed. • Comparative studies show that prediction accuracy of wind power is improved. - Abstract: Wind power forecasting can improve the economical and technical integration of wind energy into the existing electricity grid. Due to its intermittency and randomness, it is hard to forecast wind power accurately. For the purpose of utilizing wind power to the utmost extent, it is very important to make an accurate prediction of the output power of a wind farm under the premise of guaranteeing the security and the stability of the operation of the power system. In this paper, a hybrid model (LSSVM–GSA) based on the least squares support vector machine (LSSVM) and gravitational search algorithm (GSA) is proposed to forecast the short-term wind power. As the kernel function and the related parameters of the LSSVM have a great influence on the performance of the prediction model, the paper establishes LSSVM model based on different kernel functions for short-term wind power prediction. And then an optimal kernel function is determined and the parameters of the LSSVM model are optimized by using GSA. Compared with the Back Propagation (BP) neural network and support vector machine (SVM) model, the simulation results show that the hybrid LSSVM–GSA model based on exponential radial basis kernel function and GSA has higher accuracy for short-term wind power prediction. Therefore, the proposed LSSVM–GSA is a better model for short-term wind power prediction

  10. Developing relations between soil erodibilty factors in two different soil erosion prediction models (USLE/RUSLE and wWEPP) and fludization bed technique for mechanical soil cohesion

    Science.gov (United States)

    Soil erosion models are valuable analysis tools that scientists and engineers use to examine observed data sets and predict the effects of possible future soil loss. In the area of water erosion, a variety of modeling technologies are available, ranging from solely qualitative models, to merely quan...

  11. An appraisal of wind speed distribution prediction by soft computing methodologies: A comparative study

    International Nuclear Information System (INIS)

    Petković, Dalibor; Shamshirband, Shahaboddin; Anuar, Nor Badrul; Saboohi, Hadi; Abdul Wahab, Ainuddin Wahid; Protić, Milan; Zalnezhad, Erfan; Mirhashemi, Seyed Mohammad Amin

    2014-01-01

    Highlights: • Probabilistic distribution functions of wind speed. • Two parameter Weibull probability distribution. • To build an effective prediction model of distribution of wind speed. • Support vector regression application as probability function for wind speed. - Abstract: The probabilistic distribution of wind speed is among the more significant wind characteristics in examining wind energy potential and the performance of wind energy conversion systems. When the wind speed probability distribution is known, the wind energy distribution can be easily obtained. Therefore, the probability distribution of wind speed is a very important piece of information required in assessing wind energy potential. For this reason, a large number of studies have been established concerning the use of a variety of probability density functions to describe wind speed frequency distributions. Although the two-parameter Weibull distribution comprises a widely used and accepted method, solving the function is very challenging. In this study, the polynomial and radial basis functions (RBF) are applied as the kernel function of support vector regression (SVR) to estimate two parameters of the Weibull distribution function according to previously established analytical methods. Rather than minimizing the observed training error, SVR p oly and SVR r bf attempt to minimize the generalization error bound, so as to achieve generalized performance. According to the experimental results, enhanced predictive accuracy and capability of generalization can be achieved using the SVR approach compared to other soft computing methodologies

  12. Effect of accuracy of wind power prediction on power system operator

    Science.gov (United States)

    Schlueter, R. A.; Sigari, G.; Costi, T.

    1985-01-01

    This research project proposed a modified unit commitment that schedules connection and disconnection of generating units in response to load. A modified generation control is also proposed that controls steam units under automatic generation control, fast responding diesels, gas turbines and hydro units under a feedforward control, and wind turbine array output under a closed loop array control. This modified generation control and unit commitment require prediction of trend wind power variation one hour ahead and the prediction of error in this trend wind power prediction one half hour ahead. An improved meter for predicting trend wind speed variation is developed. Methods for accurately simulating the wind array power from a limited number of wind speed prediction records was developed. Finally, two methods for predicting the error in the trend wind power prediction were developed. This research provides a foundation for testing and evaluating the modified unit commitment and generation control that was developed to maintain operating reliability at a greatly reduced overall production cost for utilities with wind generation capacity.

  13. How Many Model Evaluations Are Required To Predict The AEP Of A Wind Power Plant?

    International Nuclear Information System (INIS)

    Murcia, J P; Réthoré, P E; Natarajan, A; Sørensen, J D

    2015-01-01

    Wind farm flow models have advanced considerably with the use of large eddy simulations (LES) and Reynolds averaged Navier-Stokes (RANS) computations. The main limitation of these techniques is their high computational time requirements; which makes their use for wind farm annual energy production (AEP) predictions expensive. The objective of the present paper is to minimize the number of model evaluations required to capture the wind power plant's AEP using stationary wind farm flow models. Polynomial chaos techniques are proposed based on arbitrary Weibull distributed wind speed and Von Misses distributed wind direction. The correlation between wind direction and wind speed are captured by defining Weibull-parameters as functions of wind direction. In order to evaluate the accuracy of these methods the expectation and variance of the wind farm power distributions are compared against the traditional binning method with trapezoidal and Simpson's integration rules.The wind farm flow model used in this study is the semi-empirical wake model developed by Larsen [1]. Three test cases are studied: a single turbine, a simple and a real offshore wind power plant. A reduced number of model evaluations for a general wind power plant is proposed based on the convergence of the present method for each case. (paper)

  14. Coordinated Voltage Control of a Wind Farm based on Model Predictive Control

    DEFF Research Database (Denmark)

    Zhao, Haoran; Wu, Qiuwei; Guo, Qinglai

    2016-01-01

    This paper presents an autonomous wind farm voltage controller based on Model Predictive Control (MPC). The reactive power compensation and voltage regulation devices of the wind farm include Static Var Compensators (SVCs), Static Var Generators (SVGs), Wind Turbine Generators (WTGs) and On...... are calculated based on an analytical method to improve the computation efficiency and overcome the convergence problem. Two control modes are designed for both voltage violated and normal operation conditions. A wind farm with 20 wind turbines was used to conduct case studies to verify the proposed coordinated...

  15. Validated Loads Prediction Models for Offshore Wind Turbines for Enhanced Component Reliability

    DEFF Research Database (Denmark)

    Koukoura, Christina

    To improve the reliability of offshore wind turbines, accurate prediction of their response is required. Therefore, validation of models with site measurements is imperative. In the present thesis a 3.6MW pitch regulated-variable speed offshore wind turbine on a monopole foundation is built...... are used for the modification of the sub-structure/foundation design for possible material savings. First, the background of offshore wind engineering, including wind-wave conditions, support structure, blade loading and wind turbine dynamics are presented. Second, a detailed description of the site...

  16. A study of single multiplicative neuron model with nonlinear filters for hourly wind speed prediction

    International Nuclear Information System (INIS)

    Wu, Xuedong; Zhu, Zhiyu; Su, Xunliang; Fan, Shaosheng; Du, Zhaoping; Chang, Yanchao; Zeng, Qingjun

    2015-01-01

    Wind speed prediction is one important methods to guarantee the wind energy integrated into the whole power system smoothly. However, wind power has a non–schedulable nature due to the strong stochastic nature and dynamic uncertainty nature of wind speed. Therefore, wind speed prediction is an indispensable requirement for power system operators. Two new approaches for hourly wind speed prediction are developed in this study by integrating the single multiplicative neuron model and the iterated nonlinear filters for updating the wind speed sequence accurately. In the presented methods, a nonlinear state–space model is first formed based on the single multiplicative neuron model and then the iterated nonlinear filters are employed to perform dynamic state estimation on wind speed sequence with stochastic uncertainty. The suggested approaches are demonstrated using three cases wind speed data and are compared with autoregressive moving average, artificial neural network, kernel ridge regression based residual active learning and single multiplicative neuron model methods. Three types of prediction errors, mean absolute error improvement ratio and running time are employed for different models’ performance comparison. Comparison results from Tables 1–3 indicate that the presented strategies have much better performance for hourly wind speed prediction than other technologies. - Highlights: • Developed two novel hybrid modeling methods for hourly wind speed prediction. • Uncertainty and fluctuations of wind speed can be better explained by novel methods. • Proposed strategies have online adaptive learning ability. • Proposed approaches have shown better performance compared with existed approaches. • Comparison and analysis of two proposed novel models for three cases are provided

  17. Stochastic Prediction of Wind Generating Resources Using the Enhanced Ensemble Model for Jeju Island’s Wind Farms in South Korea

    OpenAIRE

    Deockho Kim; Jin Hur

    2017-01-01

    Due to the intermittency of wind power generation, it is very hard to manage its system operation and planning. In order to incorporate higher wind power penetrations into power systems that maintain secure and economic power system operation, an accurate and efficient estimation of wind power outputs is needed. In this paper, we propose the stochastic prediction of wind generating resources using an enhanced ensemble model for Jeju Island’s wind farms in South Korea. When selecting the poten...

  18. Predicting Faults in Wind Turbines Using SCADA Data

    DEFF Research Database (Denmark)

    Borchersen, Anders Bech; Larsen, Jesper Abildgaard; Stoustrup, Jakob

    2013-01-01

    The cost of operation and maintenance of wind turbines is a significant part of the overall cost of wind turbines. To reduce this cost a method for enabling early fault detection is proposed and tested in this paper. The method is taking advantage of the fact that wind turbines in wind farms...... and tested on historical Supervisory Control And Data Acquisition (SCADA) data from nine operational turbines over a testing period of nine months. The performance of the fault detection is found to be acceptable based on the testing period. During the testing period several gear related services were...

  19. Runoff erosion

    OpenAIRE

    Evelpidou, Niki (Ed.); Cordier, Stephane (Ed.); Merino, Agustin (Ed.); Figueiredo, Tomás de (Ed.); Centeri, Csaba (Ed.)

    2013-01-01

    Table of Contents PART I – THEORY OF RUNOFF EROSION CHAPTER 1 - RUNOFF EROSION – THE MECHANISMS CHAPTER 2 - LARGE SCALE APPROACHES OF RUNOFF EROSION CHAPTER 3 - MEASURING PRESENT RUNOFF EROSION CHAPTER 4 - MODELLING RUNOFF EROSION CHAPTER 5 - RUNOFF EROSION AND HUMAN SOCIETIES: THE INFLUENCE OF LAND USE AND MANAGEMENT PRACTICES ON SOIL EROSION PART II - CASE STUDIES CASE STUDIES – INTRODUCTION: RUNOFF EROSION IN MEDITERRANEAN AREA CASE STUDY 1: Soil Erosion Risk...

  20. Erosion corrosion in power plant piping systems - Calculation code for predicting wall thinning

    International Nuclear Information System (INIS)

    Kastner, W.; Erve, M.; Henzel, N.; Stellwag, B.

    1990-01-01

    Extensive experimental and theoretical investigations have been performed to develop a calculation code for wall thinning due to erosion corrosion in power plant piping systems. The so-called WATHEC code can be applied to single-phase water flow as well as to two-phase water/steam flow. Only input data which are available to the operator of the plant are taken into consideration. Together with a continuously updated erosion corrosion data base the calculation code forms one element of a weak point analysis for power plant piping systems which can be applied to minimize material loss due to erosion corrosion, reduce non-destructive testing and curtail monitoring programs for piping systems, recommend life-extending measures. (author). 12 refs, 17 figs

  1. Development of Wind Farm AEP Prediction Program Considering Directional Wake Effect

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Kyoungboo; Cho, Kyungho; Huh, Jongchul [Jeju Nat’l Univ., Jeju (Korea, Republic of)

    2017-07-15

    For accurate AEP prediction in a wind farm, it is necessary to effectively calculate the wind speed reduction and the power loss due to the wake effect in each wind direction. In this study, a computer program for AEP prediction considering directional wake effect was developed. The results of the developed program were compared with the actual AEP of the wind farm and the calculation result of existing commercial software to confirm the accuracy of prediction. The applied equations are identical with those of commercial software based on existing theories, but there is a difference in the calculation process of the detection of the wake effect area in each wind direction. As a result, the developed program predicted to be less than 1% of difference to the actual capacity factor and showed more than 2% of better results compared with the existing commercial software.

  2. Increasing the competitiveness of wind energy. New technologies for advanced wind predictability

    International Nuclear Information System (INIS)

    Bertolotti, Fabio

    2013-01-01

    The performance of thermal and nuclear power plants is assessed routinely and precisely, whereas the performance assessment of wind turbines is lagging far behind. This increases operational costs, reduces energy capture, and makes wind energy less competitive. The paper presents a technology and system with improved 24-h power forecasting, as well as condition monitoring of the rotor blades. The system can be employed by any wind power plant and offers potentials to increase the competitiveness of the power industry. (orig.)

  3. Short-term prediction method of wind speed series based on fractal interpolation

    International Nuclear Information System (INIS)

    Xiu, Chunbo; Wang, Tiantian; Tian, Meng; Li, Yanqing; Cheng, Yi

    2014-01-01

    Highlights: • An improved fractal interpolation prediction method is proposed. • The chaos optimization algorithm is used to obtain the iterated function system. • The fractal extrapolate interpolation prediction of wind speed series is performed. - Abstract: In order to improve the prediction performance of the wind speed series, the rescaled range analysis is used to analyze the fractal characteristics of the wind speed series. An improved fractal interpolation prediction method is proposed to predict the wind speed series whose Hurst exponents are close to 1. An optimization function which is composed of the interpolation error and the constraint items of the vertical scaling factors in the fractal interpolation iterated function system is designed. The chaos optimization algorithm is used to optimize the function to resolve the optimal vertical scaling factors. According to the self-similarity characteristic and the scale invariance, the fractal extrapolate interpolation prediction can be performed by extending the fractal characteristic from internal interval to external interval. Simulation results show that the fractal interpolation prediction method can get better prediction result than others for the wind speed series with the fractal characteristic, and the prediction performance of the proposed method can be improved further because the fractal characteristic of its iterated function system is similar to that of the predicted wind speed series

  4. Prediction of wind power potential by wind speed probability distribution in a hilly terrain near Bh

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Siraj; Diwakar, Nilesh

    2010-09-15

    Daily wind speed data in metre per second and its direction of flow in degree were recorded from of the India Meteorological Department for a site near the Bhopal Airport for the period of eleven years. The influence of roughness of the terrain, obstacles and topography in terms of contour for the area were also taken into consideration. These data were analysed using WAsP programme and regional wind climate of the area was determined. It is seen from the analysis of the wind speed data and keeping the topographical variation of terrain, exploitable wind speed is experienced at 50 m.

  5. Application of a ray theory model to the prediction of noise emissions from isolated wind turbines and wind parks

    International Nuclear Information System (INIS)

    Prospathopoulos, John M.; Voutsinas, Spyros G.

    2006-01-01

    Various propagation models have been developed to estimate the level of noise near residential areas. Predictions and measurements have proven that proper modelling of the propagation medium is of particular importance. In the present work, calculations are performed using a ray theory methodology. The ray trajectory and transport equations are derived from the linear acoustics equations for a moving medium in three dimensions. Ground and atmospheric absorption, wave refraction and diffraction and atmospheric turbulence are taken into account by introducing appropriate coefficients in the equations. In the case of a wind turbine (W/T) it is assumed that noise is produced by a point source located at the rotor centre. Given the sound power spectrum, the noise spectrum at the receiver is obtained by solving the axisymmetric propagation problem. The procedure consists of (a) finding the eigenrays, (b) calculating the energy losses along the eigenrays and (c) synthesizing the sound pressure level (SPL) by superposing the contributions of the eigenrays. In the case of a wind park the total SPL is calculated by superposing the contributions of all W/Ts. Application is made to five cases of isolated W/Ts in terrains of varying complexity. In flat or even smooth terrain the predictions agree well with the measurements. In complex terrain the predictions can be considered satisfactory, taking into account the assumption of constant wind velocity profile. Application to a wind park shows clearly the influence of the terrain on the wind velocity and consequently on the SPL. (Author)

  6. A critical discussion on the applicability of Compound Topographic Index (CTI) for predicting ephemeral gully erosion

    Science.gov (United States)

    Casalí, Javier; Chahor, Youssef; Giménez, Rafael; Campo-Bescós, Miguel

    2016-04-01

    The so-called Compound Topographic Index (CTI) can be calculated for each grid cell in a DEM and be used to identify potential locations for ephemeral gullies (e. g.) based on land topography (CTI = A.S.PLANC, where A is upstream drainage area, S is local slope and PLANC is planform curvature, a measure of the landscape convergence) (Parker et al., 2007). It can be shown that CTI represents stream power per unit bed area and it considers the major parameters controlling the pattern and intensity of concentrated surface runoff in the field (Parker et al., 2007). However, other key variables controlling e.g. erosion (e. g. e.) such as soil characteristics, land-use and management, are not had into consideration. The critical CTI value (CTIc) "represents the intensity of concentrated overland flow necessary to initiate erosion and channelised flow under a given set of circumstances" (Parker et al., 2007). AnnAGNPS (Annualized Agriculture Non-Point Source) pollution model is an important management tool developed by (USDA) and uses CTI to locate potential ephemeral gullies. Then, and depending on rainfall characteristics of the period simulated by AnnAGNPS, potential e. g. can become "actual", and be simulated by the model accordingly. This paper presents preliminary results and a number of considerations after evaluating the CTI tool in Navarre. CTIc values found are similar to those cited by other authors, and the e. g. networks that on average occur in the area have been located reasonably well. After our experience we believe that it is necessary to distinguish between the CTIc corresponding to the location of headcuts whose migrations originate the e. g. (CTIc1); and the CTIc necessary to represent the location of the gully networks in the watershed (CTIc2), where gully headcuts are located in the upstream end of the gullies. Most scientists only consider one CTIc value, although, from our point of view, the two situations are different. CTIc1 would represent the

  7. On wake modeling, wind-farm gradients, and AEP predictions at the Anholt wind farm

    Directory of Open Access Journals (Sweden)

    A. Peña

    2018-04-01

    Full Text Available We investigate wake effects at the Anholt offshore wind farm in Denmark, which is a farm experiencing strong horizontal wind-speed gradients because of its size and proximity to land. Mesoscale model simulations are used to study the horizontal wind-speed gradients over the wind farm. From analysis of the mesoscale simulations and supervisory control and data acquisition (SCADA, we show that for westerly flow in particular, there is a clear horizontal wind-speed gradient over the wind farm. We also use the mesoscale simulations to derive the undisturbed inflow conditions that are coupled with three commonly used wake models: two engineering approaches (the Park and G. C. Larsen models and a linearized Reynolds-averaged Navier–Stokes approach (Fuga. The effect of the horizontal wind-speed gradient on annual energy production estimates is not found to be critical compared to estimates from both the average undisturbed wind climate of all turbines' positions and the undisturbed wind climate of a position in the middle of the wind farm. However, annual energy production estimates can largely differ when using wind climates at positions that are strongly influenced by the horizontal wind-speed gradient. When looking at westerly flow wake cases, where the impact of the horizontal wind-speed gradient on the power of the undisturbed turbines is largest, the wake models agree with the SCADA fairly well; when looking at a southerly flow case, where the wake losses are highest, the wake models tend to underestimate the wake loss. With the mesoscale-wake model setup, we are also able to estimate the capacity factor of the wind farm rather well when compared to that derived from the SCADA. Finally, we estimate the uncertainty of the wake models by bootstrapping the SCADA. The models tend to underestimate the wake losses (the median relative model error is 8.75 % and the engineering wake models are as uncertain as Fuga. These results are specific for

  8. Synthesising empirical results to improve predictions of post-wildfire runoff and erosion response

    Science.gov (United States)

    Richard A. Shakesby; John A. Moody; Deborah A. Martin; Pete Robichaud

    2016-01-01

    Advances in research into wildfire impacts on runoff and erosion have demonstrated increasing complexity of controlling factors and responses, which, combined with changing fire frequency, present challenges for modellers. We convened a conference attended by experts and practitioners in post-wildfire impacts, meteorology and related research, including...

  9. Predicting soil erosion using Rusle and NDVI time series from TM Landsat 5

    Directory of Open Access Journals (Sweden)

    Daniel Fonseca de Carvalho

    2014-03-01

    Full Text Available The objective of this work was to evaluate the seasonal variation of soil cover and rainfall erosivity, and their influences on the revised universal soil loss equation (Rusle, in order to estimate watershed soil losses in a temporal scale. Twenty-two TM Landsat 5 images from 1986 to 2009 were used to estimate soil use and management factor (C factor. A corresponding rainfall erosivity factor (R factor was considered for each image, and the other factors were obtained using the standard Rusle method. Estimated soil losses were grouped into classes and ranged from 0.13 Mg ha-1 on May 24, 2009 (dry season to 62.0 Mg ha-1 on March 11, 2007 (rainy season. In these dates, maximum losses in the watershed were 2.2 and 781.5 Mg ha-1 , respectively. Mean annual soil loss in the watershed was 109.5 Mg ha-1 , but the central area, with a loss of nearly 300.0 Mg ha-1 , was characterized as a site of high water-erosion risk. The use of C factor obtained from remote sensing data, associated to corresponding R factor, was fundamental to evaluate the soil erosion estimated by the Rusle in different seasons, unlike of other studies which keep these factors constant throughout time.

  10. Estimation of uncertainty of wind energy predictions with application to weather routing and wind power generation

    CERN Document Server

    Zastrau, David

    2017-01-01

    Wind drives in combination with weather routing can lower the fuel consumption of cargo ships significantly. For this reason, the author describes a mathematical method based on quantile regression for a probabilistic estimate of the wind propulsion force on a ship route.

  11. Development of a catchment/landscape erosion prediction model (MINErosion 4) for post-mining landscapes in Central Queensland, Australia.

    Science.gov (United States)

    Khalifa, Ashraf; Yu, Bofu; Ghadiri, Hossain; Carroll, Chris; So, Hwat-Bing

    2010-05-01

    industry further require a tool that enables them to predict and manage the impact of on-site and offsite discharges from storm events and to identify the areas of high erosion risk. Work is in progress to develop a user friendly package MINErosion 4 by combining the hillslope model MINErosion 3 with ARC-GIS 9, which allows the prediction of sediment losses and deposition from proposed post-mining landscapes (designed based on criteria derived from MINErosion3) subjected to rainstorms with known recurrence intervals for selected locations. An option is provided to derive mean annual soil loss from these catchments and landscapes. Soil samples were collected from various locations on 6 minesites to provide a measure of variability in erodibilities across a minesite. The model was validated against 9 years of catchment data collected from previous projects and the agreement between predicted (Y) and measured (X) soil losses are good with regression equations of Y = 0.919 X (R2 = 0.81) for individual rainstorms, and Y= 1.473 X (R2 = 0.726) for average annual soil loss.

  12. Near Real Time MISR Wind Observations for Numerical Weather Prediction

    Science.gov (United States)

    Mueller, K. J.; Protack, S.; Rheingans, B. E.; Hansen, E. G.; Jovanovic, V. M.; Baker, N.; Liu, J.; Val, S.

    2014-12-01

    The Multi-angle Imaging SpectroRadiometer (MISR) project, in association with the NASA Langley Atmospheric Science Data Center (ASDC), has this year adapted its original production software to generate near-real time (NRT) cloud-motion winds as well as radiance imagery from all nine MISR cameras. These products are made publicly available at the ASDC with a latency of less than 3 hours. Launched aboard the sun-synchronous Terra platform in 1999, the MISR instrument continues to acquire near-global, 275 m resolution, multi-angle imagery. During a single 7 minute overpass of any given area, MISR retrieves the stereoscopic height and horizontal motion of clouds from the multi-angle data, yielding meso-scale near-instantaneous wind vectors. The ongoing 15-year record of MISR height-resolved winds at 17.6 km resolution has been validated against independent data sources. Low-level winds dominate the sampling, and agree to within ±3 ms-1 of collocated GOES and other observations. Low-level wind observations are of particular interest to weather forecasting, where there is a dearth of observations suitable for assimilation, in part due to reliability concerns associated with winds whose heights are assigned by the infrared brightness temperature technique. MISR cloud heights, on the other hand, are generated from stereophotogrammetric pattern matching of visible radiances. MISR winds also address data gaps in the latitude bands between geostationary satellite coverage and polar orbiting instruments that obtain winds from multiple overpasses (e.g. MODIS). Observational impact studies conducted by the Naval Research Laboratory (NRL) and by the German Weather Service (Deutscher Wetterdienst) have both demonstrated forecast improvements when assimilating MISR winds. An impact assessment using the GEOS-5 system is currently in progress. To benefit air quality forecasts, the MISR project is currently investigating the feasibility of generating near-real time aerosol products.

  13. Development and Application of Advanced Weather Prediction Technologies for the Wind Energy Industry (Invited)

    Science.gov (United States)

    Mahoney, W. P.; Wiener, G.; Liu, Y.; Myers, W.; Johnson, D.

    2010-12-01

    Wind energy decision makers are required to make critical judgments on a daily basis with regard to energy generation, distribution, demand, storage, and integration. Accurate knowledge of the present and future state of the atmosphere is vital in making these decisions. As wind energy portfolios expand, this forecast problem is taking on new urgency because wind forecast inaccuracies frequently lead to substantial economic losses and constrain the national expansion of renewable energy. Improved weather prediction and precise spatial analysis of small-scale weather events are crucial for renewable energy management. In early 2009, the National Center for Atmospheric Research (NCAR) began a collaborative project with Xcel Energy Services, Inc. to perform research and develop technologies to improve Xcel Energy's ability to increase the amount of wind energy in their generation portfolio. The agreement and scope of work was designed to provide highly detailed, localized wind energy forecasts to enable Xcel Energy to more efficiently integrate electricity generated from wind into the power grid. The wind prediction technologies are designed to help Xcel Energy operators make critical decisions about powering down traditional coal and natural gas-powered plants when sufficient wind energy is predicted. The wind prediction technologies have been designed to cover Xcel Energy wind resources spanning a region from Wisconsin to New Mexico. The goal of the project is not only to improve Xcel Energy’s wind energy prediction capabilities, but also to make technological advancements in wind and wind energy prediction, expand our knowledge of boundary layer meteorology, and share the results across the renewable energy industry. To generate wind energy forecasts, NCAR is incorporating observations of current atmospheric conditions from a variety of sources including satellites, aircraft, weather radars, ground-based weather stations, wind profilers, and even wind sensors on

  14. 7 CFR 610.13 - Equations for predicting soil loss due to wind erosion.

    Science.gov (United States)

    2010-01-01

    ... from the American Society of Agronomy, Madison, Wisconsin. In addition, the use of the WEQ in NRCS is explained in the Natural Resources Conservation Service (NRCS) National Agronomy Manual, 190-V-NAM, second...

  15. An adaptive short-term prediction scheme for wind energy storage management

    International Nuclear Information System (INIS)

    Blonbou, Ruddy; Monjoly, Stephanie; Dorville, Jean-Francois

    2011-01-01

    Research highlights: → We develop a real time algorithm for grid-connected wind energy storage management. → The method aims to guarantee, with ±5% error margin, the power sent to the grid. → Dynamic scheduling of energy storage is based on short-term energy prediction. → Accurate predictions reduce the need in storage capacity. -- Abstract: Efficient forecasting scheme that includes some information on the likelihood of the forecast and based on a better knowledge of the wind variations characteristics along with their influence on power output variation is of key importance for the optimal integration of wind energy in island's power system. In the Guadeloupean archipelago (French West-Indies), with a total wind power capacity of 25 MW; wind energy can represent up to 5% of the instantaneous electricity production. At this level, wind energy contribution can be equivalent to the current network primary control reserve, which causes balancing difficult. The share of wind energy is due to grow even further since the objective is set to reach 118 MW by 2020. It is an absolute evidence for the network operator that due to security concerns of the electrical grid, the share of wind generation should not increase unless solutions are found to solve the prediction problem. The University of French West-Indies and Guyana has developed a short-term wind energy prediction scheme that uses artificial neural networks and adaptive learning procedures based on Bayesian approach and Gaussian approximation. This paper reports the results of the evaluation of the proposed approach; the improvement with respect to the simple persistent prediction model was globally good. A discussion on how such a tool combined with energy storage capacity could help to smooth the wind power variation and improve the wind energy penetration rate into island utility network is also proposed.

  16. Reduction of wind power induced reserve requirements by advanced shortest-term forecasts and prediction intervals

    Energy Technology Data Exchange (ETDEWEB)

    Dobschinski, Jan; Wessel, Arne; Lange, Bernhard; Bremen, Lueder von [Fraunhofer Institut fuer Windenergie und Energiesystemtechnik (IWES), Kassel (Germany)

    2009-07-01

    In electricity systems with large penetration of wind power, the limited predictability of the wind power generation leads to an increase in reserve and balancing requirements. At first the present study concentrates on the capability of dynamic day-ahead prediction intervals to reduce the wind power induced reserve and balancing requirements. Alternatively the reduction of large forecast errors of the German wind power generation by using advanced shortest-term predictions has been evaluated in a second approach. With focus on the allocation of minute reserve power the aim is to estimate the maximal remaining uncertainty after trading activities on the intraday market. Finally both approaches were used in a case study concerning the reserve requirements induced by the total German wind power expansion in 2007. (orig.)

  17. Short-Term Wind Speed Prediction Using EEMD-LSSVM Model

    Directory of Open Access Journals (Sweden)

    Aiqing Kang

    2017-01-01

    Full Text Available Hybrid Ensemble Empirical Mode Decomposition (EEMD and Least Square Support Vector Machine (LSSVM is proposed to improve short-term wind speed forecasting precision. The EEMD is firstly utilized to decompose the original wind speed time series into a set of subseries. Then the LSSVM models are established to forecast these subseries. Partial autocorrelation function is adopted to analyze the inner relationships between the historical wind speed series in order to determine input variables of LSSVM models for prediction of every subseries. Finally, the superposition principle is employed to sum the predicted values of every subseries as the final wind speed prediction. The performance of hybrid model is evaluated based on six metrics. Compared with LSSVM, Back Propagation Neural Networks (BP, Auto-Regressive Integrated Moving Average (ARIMA, combination of Empirical Mode Decomposition (EMD with LSSVM, and hybrid EEMD with ARIMA models, the wind speed forecasting results show that the proposed hybrid model outperforms these models in terms of six metrics. Furthermore, the scatter diagrams of predicted versus actual wind speed and histograms of prediction errors are presented to verify the superiority of the hybrid model in short-term wind speed prediction.

  18. RANS Based Methodology for Predicting the Influence of Leading Edge Erosion on Airfoil Performance

    Energy Technology Data Exchange (ETDEWEB)

    Langel, Christopher M. [Univ. of California, Davis, CA (United States). Dept. of Mechanical and Aerospace Engineering; Chow, Raymond C. [Univ. of California, Davis, CA (United States). Dept. of Mechanical and Aerospace Engineering; van Dam, C. P. [Univ. of California, Davis, CA (United States). Dept. of Mechanical and Aerospace Engineering; Maniaci, David Charles [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Wind Energy Technologies Dept.

    2017-10-01

    The impact of surface roughness on flows over aerodynamically designed surfaces is of interested in a number of different fields. It has long been known the surface roughness will likely accelerate the laminar- turbulent transition process by creating additional disturbances in the boundary layer. However, there are very few tools available to predict the effects surface roughness will have on boundary layer flow. There are numerous implications of the premature appearance of a turbulent boundary layer. Increases in local skin friction, boundary layer thickness, and turbulent mixing can impact global flow properties compounding the effects of surface roughness. With this motivation, an investigation into the effects of surface roughness on boundary layer transition has been conducted. The effort involved both an extensive experimental campaign, and the development of a high fidelity roughness model implemented in a R ANS solver. Vast a mounts of experimental data was generated at the Texas A&M Oran W. Nicks Low Speed Wind Tunnel for the calibration and validation of the roughness model described in this work, as well as future efforts. The present work focuses on the development of the computational model including a description of the calibration process. The primary methodology presented introduces a scalar field variable and associated transport equation that interacts with a correlation based transition model. The additional equation allows for non-local effects of surface roughness to be accounted for downstream of rough wall sections while maintaining a "local" formulation. The scalar field is determined through a boundary condition function that has been calibrated to flat plate cases with sand grain roughness. The model was initially tested on a NACA 0012 airfoil with roughness strips applied to the leading edge. Further calibration of the roughness model was performed using results from the companion experimental study on a NACA 633 -418 airfoil

  19. High-altitude wind prediction and measurement technology assessment

    Science.gov (United States)

    2009-06-30

    The principles and operational characteristics of balloon and radar-based techniques for measuring upper air winds in support of launches and recoveries are presented. Though either a balloon or radar system could serve as a standalone system, the sa...

  20. The effects of tropical wind data on the prediction of ultralong waves

    Science.gov (United States)

    Baker, W. E.

    1981-01-01

    The influence of tropical wind data on the prediction of planetary waves were studied. Two assimilation experiments were performed, one with and one without FGGE tropical winds. The planetary wave error was then analyzed in 72 h forecasts from the initial conditions provided by the two assimilations.

  1. A new wind power prediction method based on chaotic theory and Bernstein Neural Network

    International Nuclear Information System (INIS)

    Wang, Cong; Zhang, Hongli; Fan, Wenhui; Fan, Xiaochao

    2016-01-01

    The accuracy of wind power prediction is important for assessing the security and economy of the system operation when wind power connects to the grids. However, multiple factors cause a long delay and large errors in wind power prediction. Hence, efficient wind power forecasting approaches are still required for practical applications. In this paper, a new wind power forecasting method based on Chaos Theory and Bernstein Neural Network (BNN) is proposed. Firstly, the largest Lyapunov exponent as a judgment for wind power system's chaotic behavior is made. Secondly, Phase Space Reconstruction (PSR) is used to reconstruct the wind power series' phase space. Thirdly, the prediction model is constructed using the Bernstein polynomial and neural network. Finally, the weights and thresholds of the model are optimized by Primal Dual State Transition Algorithm (PDSTA). The practical hourly data of wind power generation in Xinjiang is used to test this forecaster. The proposed forecaster is compared with several current prominent research findings. Analytical results indicate that the forecasting error of PDSTA + BNN is 3.893% for 24 look-ahead hours, and has lower errors obtained compared with the other forecast methods discussed in this paper. The results of all cases studying confirm the validity of the new forecast method. - Highlights: • Lyapunov exponent is used to verify chaotic behavior of wind power series. • Phase Space Reconstruction is used to reconstruct chaotic wind power series. • A new Bernstein Neural Network to predict wind power series is proposed. • Primal dual state transition algorithm is chosen as the training strategy of BNN.

  2. Using data-driven approach for wind power prediction: A comparative study

    International Nuclear Information System (INIS)

    Taslimi Renani, Ehsan; Elias, Mohamad Fathi Mohamad; Rahim, Nasrudin Abd.

    2016-01-01

    Highlights: • Double exponential smoothing is the most accurate model in wind speed prediction. • A two-stage feature selection method is proposed to select most important inputs. • Direct prediction illustrates better accuracy than indirect prediction. • Adaptive neuro fuzzy inference system outperforms data mining algorithms. • Random forest performs the worst compared to other data mining algorithm. - Abstract: Although wind energy is intermittent and stochastic in nature, it is increasingly important in the power generation due to its sustainability and pollution-free. Increased utilization of wind energy sources calls for more robust and efficient prediction models to mitigate uncertainties associated with wind power. This research compares two different approaches in wind power forecasting which are indirect and direct prediction methods. In indirect method, several times series are applied to forecast the wind speed, whereas the logistic function with five parameters is then used to forecast the wind power. In this study, backtracking search algorithm with novel crossover and mutation operators is employed to find the best parameters of five-parameter logistic function. A new feature selection technique, combining the mutual information and neural network is proposed in this paper to extract the most informative features with a maximum relevancy and minimum redundancy. From the comparative study, the results demonstrate that, in the direct prediction approach where the historical weather data are used to predict the wind power generation directly, adaptive neuro fuzzy inference system outperforms five data mining algorithms namely, random forest, M5Rules, k-nearest neighbor, support vector machine and multilayer perceptron. Moreover, it is also found that the mean absolute percentage error of the direct prediction method using adaptive neuro fuzzy inference system is 1.47% which is approximately less than half of the error obtained with the

  3. Soil Erosion. LC Science Tracer Bullet.

    Science.gov (United States)

    Buydos, John F., Comp.

    Soil erosion is the detachment and movement of topsoil or soil material from the upper part of the soil profile. It may occur in the form of rill, gully, sheet, or wind erosion. Agents of erosion may be water, wind, glacial ice, agricultural implements, machinery, and animals. Soil conservation measures require a thorough understanding of the…

  4. On wake modeling, wind-farm gradients and AEP predictions at the Anholt wind farm

    DEFF Research Database (Denmark)

    Pena Diaz, Alfredo; Hansen, Kurt Schaldemose; Ott, Søren

    2017-01-01

    of the mesoscale simulations and supervisory control and data acquisition (SCADA), we show that for westerly flow in particular, there is a clear horizontal wind-speed gradient over the wind farm. We also use the mesoscale simulations to derive the undisturbed inflow conditions that are coupled with three commonly....... When looking at westerly flow wake cases, where the impact of the horizontal wind-speed gradient on the power of the undisturbed turbines is largest, the wake models agree with the SCADA fairly well; when looking at a southerly flow case, where the wake losses are highest, the wake models tend...... to underestimate the wake loss. With the mesoscale-wake model setup, we are also able to estimate the capacity factor of the wind farm rather well when compared to that derived from the SCADA. Finally, we estimate the uncertainty of the wake models by bootstrapping the SCADA. The models tend to underestimate...

  5. Ultra-Short-Term Wind Power Prediction Using a Hybrid Model

    Science.gov (United States)

    Mohammed, E.; Wang, S.; Yu, J.

    2017-05-01

    This paper aims to develop and apply a hybrid model of two data analytical methods, multiple linear regressions and least square (MLR&LS), for ultra-short-term wind power prediction (WPP), for example taking, Northeast China electricity demand. The data was obtained from the historical records of wind power from an offshore region, and from a wind farm of the wind power plant in the areas. The WPP achieved in two stages: first, the ratios of wind power were forecasted using the proposed hybrid method, and then the transformation of these ratios of wind power to obtain forecasted values. The hybrid model combines the persistence methods, MLR and LS. The proposed method included two prediction types, multi-point prediction and single-point prediction. WPP is tested by applying different models such as autoregressive moving average (ARMA), autoregressive integrated moving average (ARIMA) and artificial neural network (ANN). By comparing results of the above models, the validity of the proposed hybrid model is confirmed in terms of error and correlation coefficient. Comparison of results confirmed that the proposed method works effectively. Additional, forecasting errors were also computed and compared, to improve understanding of how to depict highly variable WPP and the correlations between actual and predicted wind power.

  6. Distributed Model Predictive Control for Active Power Control of Wind Farm

    DEFF Research Database (Denmark)

    Zhao, Haoran; Wu, Qiuwei; Rasmussen, Claus Nygaard

    2014-01-01

    This paper presents the active power control of a wind farm using the Distributed Model Predictive Controller (D- MPC) via dual decomposition. Different from the conventional centralized wind farm control, multiple objectives such as power reference tracking performance and wind turbine load can...... be considered to achieve a trade-off between them. Additionally, D- MPC is based on communication among the subsystems. Through the interaction among the neighboring subsystems, the global optimization could be achieved, which significantly reduces the computation burden. It is suitable for the modern large......-scale wind farm control....

  7. Upper Gastrointestinal Symptoms Predictive of Candida Esophagitis and Erosive Esophagitis in HIV and Non-HIV Patients

    Science.gov (United States)

    Takahashi, Yuta; Nagata, Naoyoshi; Shimbo, Takuro; Nishijima, Takeshi; Watanabe, Koji; Aoki, Tomonori; Sekine, Katsunori; Okubo, Hidetaka; Watanabe, Kazuhiro; Sakurai, Toshiyuki; Yokoi, Chizu; Mimori, Akio; Oka, Shinichi; Uemura, Naomi; Akiyama, Junichi

    2015-01-01

    Abstract Upper gastrointestinal (GI) symptoms are common in both HIV and non-HIV-infected patients, but the difference of GI symptom severity between 2 groups remains unknown. Candida esophagitis and erosive esophagitis, 2 major types of esophagitis, are seen in both HIV and non-HIV-infected patients, but differences in GI symptoms that are predictive of esophagitis between 2 groups remain unknown. We aimed to determine whether GI symptoms differ between HIV-infected and non-HIV-infected patients, and identify specific symptoms of candida esophagitis and erosive esophagitis between 2 groups. We prospectively enrolled 6011 patients (HIV, 430; non-HIV, 5581) who underwent endoscopy and completed questionnaires. Nine upper GI symptoms (epigastric pain, heartburn, acid regurgitation, hunger cramps, nausea, early satiety, belching, dysphagia, and odynophagia) were evaluated using a 7-point Likert scale. Associations between esophagitis and symptoms were analyzed by the multivariate logistic regression model adjusted for age, sex, and proton pump inhibitors. Endoscopy revealed GI-organic diseases in 33.4% (2010/6.011) of patients. The prevalence of candida esophagitis and erosive esophagitis was 11.2% and 12.1% in HIV-infected patients, respectively, whereas it was 2.9% and 10.7 % in non-HIV-infected patients, respectively. After excluding GI-organic diseases, HIV-infected patients had significantly (P symptom scores for heartburn, hunger cramps, nausea, early satiety, belching, dysphagia, and odynophagia than non-HIV-infected patients. In HIV-infected patients, any symptom was not significantly associated with CD4 cell count. In multivariate analysis, none of the 9 GI symptoms were associated with candida esophagitis in HIV-infected patients, whereas dysphagia and odynophagia were independently (P HIV-infected patients. However, heartburn and acid regurgitation were independently (P symptom scores were reliable in both HIV (α, 0.86) and non-HIV-infected patients

  8. NASA's Evolutionary Xenon Thruster (NEXT) Project Qualification Propellant Throughput Milestone: Performance, Erosion, and Thruster Service Life Prediction After 450 kg

    Science.gov (United States)

    Herman, Daniel A.

    2010-01-01

    The NASA s Evolutionary Xenon Thruster (NEXT) program is tasked with significantly improving and extending the capabilities of current state-of-the-art NSTAR thruster. The service life capability of the NEXT ion thruster is being assessed by thruster wear test and life-modeling of critical thruster components, such as the ion optics and cathodes. The NEXT Long-Duration Test (LDT) was initiated to validate and qualify the NEXT thruster propellant throughput capability. The NEXT thruster completed the primary goal of the LDT; namely to demonstrate the project qualification throughput of 450 kg by the end of calendar year 2009. The NEXT LDT has demonstrated 28,500 hr of operation and processed 466 kg of xenon throughput--more than double the throughput demonstrated by the NSTAR flight-spare. Thruster performance changes have been consistent with a priori predictions. Thruster erosion has been minimal and consistent with the thruster service life assessment, which predicts the first failure mode at greater than 750 kg throughput. The life-limiting failure mode for NEXT is predicted to be loss of structural integrity of the accelerator grid due to erosion by charge-exchange ions.

  9. Standardizing the performance evaluation of short-term wind prediction models

    DEFF Research Database (Denmark)

    Madsen, Henrik; Pinson, Pierre; Kariniotakis, G.

    2005-01-01

    Short-term wind power prediction is a primary requirement for efficient large-scale integration of wind generation in power systems and electricity markets. The choice of an appropriate prediction model among the numerous available models is not trivial, and has to be based on an objective...... evaluation of model performance. This paper proposes a standardized protocol for the evaluation of short-term wind-poser preciction systems. A number of reference prediction models are also described, and their use for performance comparison is analysed. The use of the protocol is demonstrated using results...... from both on-shore and off-shore wind forms. The work was developed in the frame of the Anemos project (EU R&D project) where the protocol has been used to evaluate more than 10 prediction systems....

  10. Development of a wind farm noise propagation prediction model - project progress to date

    International Nuclear Information System (INIS)

    Robinson, P.; Bullmore, A.; Bass, J.; Sloth, E.

    1998-01-01

    This paper describes a twelve month measurement campaign which is part of a European project (CEC Project JOR3-CT95-0051) with the aim to substantially reduce the uncertainties involved in predicting environmentally radiated noise levels from wind farms (1). This will be achieved by comparing noise levels measure at varying distances from single and multiple sources over differing complexities of terrain with those predicted using a number of currently adopted sound propagation models. Specific objectives within the project are to: establish the important parameters controlling the propagation of wind farm noise to the far field; develop a planning tool for predicting wind farm noise emission levels under practically encountered conditions; place confidence limits on the upper and lower bounds of the noise levels predicted, thus enabling developers to quantify the risk whether noise emission from wind farms will cause nuisance to nearby residents. (Author)

  11. Stochastic Prediction of Wind Generating Resources Using the Enhanced Ensemble Model for Jeju Island’s Wind Farms in South Korea

    Directory of Open Access Journals (Sweden)

    Deockho Kim

    2017-05-01

    Full Text Available Due to the intermittency of wind power generation, it is very hard to manage its system operation and planning. In order to incorporate higher wind power penetrations into power systems that maintain secure and economic power system operation, an accurate and efficient estimation of wind power outputs is needed. In this paper, we propose the stochastic prediction of wind generating resources using an enhanced ensemble model for Jeju Island’s wind farms in South Korea. When selecting the potential sites of wind farms, wind speed data at points of interest are not always available. We apply the Kriging method, which is one of spatial interpolation, to estimate wind speed at potential sites. We also consider a wind profile power law to correct wind speed along the turbine height and terrain characteristics. After that, we used estimated wind speed data to calculate wind power output and select the best wind farm sites using a Weibull distribution. Probability density function (PDF or cumulative density function (CDF is used to estimate the probability of wind speed. The wind speed data is classified along the manufacturer’s power curve data. Therefore, the probability of wind speed is also given in accordance with classified values. The average wind power output is estimated in the form of a confidence interval. The empirical data of meteorological towers from Jeju Island in Korea is used to interpolate the wind speed data spatially at potential sites. Finally, we propose the best wind farm site among the four potential wind farm sites.

  12. Wind Power Ramp Events Prediction with Hybrid Machine Learning Regression Techniques and Reanalysis Data

    Directory of Open Access Journals (Sweden)

    Laura Cornejo-Bueno

    2017-11-01

    Full Text Available Wind Power Ramp Events (WPREs are large fluctuations of wind power in a short time interval, which lead to strong, undesirable variations in the electric power produced by a wind farm. Its accurate prediction is important in the effort of efficiently integrating wind energy in the electric system, without affecting considerably its stability, robustness and resilience. In this paper, we tackle the problem of predicting WPREs by applying Machine Learning (ML regression techniques. Our approach consists of using variables from atmospheric reanalysis data as predictive inputs for the learning machine, which opens the possibility of hybridizing numerical-physical weather models with ML techniques for WPREs prediction in real systems. Specifically, we have explored the feasibility of a number of state-of-the-art ML regression techniques, such as support vector regression, artificial neural networks (multi-layer perceptrons and extreme learning machines and Gaussian processes to solve the problem. Furthermore, the ERA-Interim reanalysis from the European Center for Medium-Range Weather Forecasts is the one used in this paper because of its accuracy and high resolution (in both spatial and temporal domains. Aiming at validating the feasibility of our predicting approach, we have carried out an extensive experimental work using real data from three wind farms in Spain, discussing the performance of the different ML regression tested in this wind power ramp event prediction problem.

  13. Statistical downscaling of historical monthly mean winds over a coastal region of complex terrain. I. Predicting wind speed

    Energy Technology Data Exchange (ETDEWEB)

    Curry, Charles L. [Canadian Centre for Climate Modelling and Analysis, Environment Canada, University of Victoria, Victoria, BC (Canada); School of Earth and Ocean Sciences, University of Victoria, Victoria, BC (Canada); Kamp, Derek van der [School of Earth and Ocean Sciences, University of Victoria, Victoria, BC (Canada); Pacific Climate Impacts Consortium, University of Victoria, Victoria, BC (Canada); Monahan, Adam H. [School of Earth and Ocean Sciences, University of Victoria, Victoria, BC (Canada)

    2012-04-15

    Surface wind speed is a key climatic variable of interest in many applications, including assessments of storm-related infrastructure damage and feasibility studies of wind power generation. In this work and a companion paper (van der Kamp et al. 2011), the relationship between local surface wind and large-scale climate variables was studied using multiple regression analysis. The analysis was performed using monthly mean station data from British Columbia, Canada and large-scale climate variables (predictors) from the NCEP-2 reanalysis over the period 1979-2006. Two regression-based methodologies were compared. The first relates the annual cycle of station wind speed to that of the large-scale predictors at the closest grid box to the station. It is shown that the relatively high correlation coefficients obtained with this method are attributable to the dominant influence of region-wide seasonality, and thus contain minimal information about local wind behaviour at the stations. The second method uses interannually varying data for individual months, aggregated into seasons, and is demonstrated to contain intrinsically local information about the surface winds. The dependence of local wind speed upon large-scale predictors over a much larger region surrounding the station was also explored, resulting in 2D maps of spatial correlations. The cross-validated explained variance using the interannual method was highest in autumn and winter, ranging from 30 to 70% at about a dozen stations in the region. Reasons for the limited predictive skill of the regressions and directions for future progress are reviewed. (orig.)

  14. Enhanced Voltage Control of VSC-HVDC Connected Offshore Wind Farms Based on Model Predictive Control

    DEFF Research Database (Denmark)

    Guo, Yifei; Gao, Houlei; Wu, Qiuwei

    2018-01-01

    This paper proposes an enhanced voltage control strategy (EVCS) based on model predictive control (MPC) for voltage source converter based high voltage direct current (VSCHVDC) connected offshore wind farms (OWFs). In the proposed MPC based EVCS, all wind turbine generators (WTGs) as well...... as the wind farm side VSC are optimally coordinated to keep voltages within the feasible range and reduce system power losses. Considering the high ratio of the OWF collector system, the effects of active power outputs of WTGs on voltage control are also taken into consideration. The predictive model of VSC...

  15. A hybrid PSO-ANFIS approach for short-term wind power prediction in Portugal

    International Nuclear Information System (INIS)

    Pousinho, H.M.I.; Mendes, V.M.F.; Catalao, J.P.S.

    2011-01-01

    The increased integration of wind power into the electric grid, as nowadays occurs in Portugal, poses new challenges due to its intermittency and volatility. Wind power prediction plays a key role in tackling these challenges. The contribution of this paper is to propose a new hybrid approach, combining particle swarm optimization and adaptive-network-based fuzzy inference system, for short-term wind power prediction in Portugal. Significant improvements regarding forecasting accuracy are attainable using the proposed approach, in comparison with the results obtained with five other approaches.

  16. A hybrid PSO-ANFIS approach for short-term wind power prediction in Portugal

    Energy Technology Data Exchange (ETDEWEB)

    Pousinho, H.M.I. [Department of Electromechanical Engineering, University of Beira Interior, R. Fonte do Lameiro, 6201-001 Covilha (Portugal); Mendes, V.M.F. [Department of Electrical Engineering and Automation, Instituto Superior de Engenharia de Lisboa, R. Conselheiro Emidio Navarro, 1950-062 Lisbon (Portugal); Catalao, J.P.S. [Department of Electromechanical Engineering, University of Beira Interior, R. Fonte do Lameiro, 6201-001 Covilha (Portugal); Center for Innovation in Electrical and Energy Engineering, Instituto Superior Tecnico, Technical University of Lisbon, Av. Rovisco Pais, 1049-001 Lisbon (Portugal)

    2011-01-15

    The increased integration of wind power into the electric grid, as nowadays occurs in Portugal, poses new challenges due to its intermittency and volatility. Wind power prediction plays a key role in tackling these challenges. The contribution of this paper is to propose a new hybrid approach, combining particle swarm optimization and adaptive-network-based fuzzy inference system, for short-term wind power prediction in Portugal. Significant improvements regarding forecasting accuracy are attainable using the proposed approach, in comparison with the results obtained with five other approaches. (author)

  17. Importance of Dynamic Inflow Model Predictive Control of Wind Turbines

    DEFF Research Database (Denmark)

    Odgaard, Peter Fogh; Knudsen, Torben; Overgaard, Anders

    2015-01-01

    The efficiency of including dynamic inflow in the model based design of wind turbine controller has been discussed for many years in the wind energy community with out getting to a safe conclusion. This paper delivers a good argument in favor of including dynamic inflow. The main contributions...... pronounces. For this the well accepted NREL 5MW reference turbine simulated with FAST is used. The main result is a reduction in tower fatigue load at 22% while power error, rotor speed error, generator torque and pitch rate is improved from 2 to 33%....

  18. Estimation of Separation Buffers for Wind-Prediction Error in an Airborne Separation Assistance System

    Science.gov (United States)

    Consiglio, Maria C.; Hoadley, Sherwood T.; Allen, B. Danette

    2009-01-01

    Wind prediction errors are known to affect the performance of automated air traffic management tools that rely on aircraft trajectory predictions. In particular, automated separation assurance tools, planned as part of the NextGen concept of operations, must be designed to account and compensate for the impact of wind prediction errors and other system uncertainties. In this paper we describe a high fidelity batch simulation study designed to estimate the separation distance required to compensate for the effects of wind-prediction errors throughout increasing traffic density on an airborne separation assistance system. These experimental runs are part of the Safety Performance of Airborne Separation experiment suite that examines the safety implications of prediction errors and system uncertainties on airborne separation assurance systems. In this experiment, wind-prediction errors were varied between zero and forty knots while traffic density was increased several times current traffic levels. In order to accurately measure the full unmitigated impact of wind-prediction errors, no uncertainty buffers were added to the separation minima. The goal of the study was to measure the impact of wind-prediction errors in order to estimate the additional separation buffers necessary to preserve separation and to provide a baseline for future analyses. Buffer estimations from this study will be used and verified in upcoming safety evaluation experiments under similar simulation conditions. Results suggest that the strategic airborne separation functions exercised in this experiment can sustain wind prediction errors up to 40kts at current day air traffic density with no additional separation distance buffer and at eight times the current day with no more than a 60% increase in separation distance buffer.

  19. A hybrid measure-correlate-predict method for long-term wind condition assessment

    International Nuclear Information System (INIS)

    Zhang, Jie; Chowdhury, Souma; Messac, Achille; Hodge, Bri-Mathias

    2014-01-01

    Highlights: • A hybrid measure-correlate-predict (MCP) methodology with greater accuracy is developed. • Three sets of performance metrics are proposed to evaluate the hybrid MCP method. • Both wind speed and direction are considered in the hybrid MCP method. • The best combination of MCP algorithms is determined. • The developed hybrid MCP method is uniquely helpful for long-term wind resource assessment. - Abstract: This paper develops a hybrid measure-correlate-predict (MCP) strategy to assess long-term wind resource variations at a farm site. The hybrid MCP method uses recorded data from multiple reference stations to estimate long-term wind conditions at a target wind plant site with greater accuracy than is possible with data from a single reference station. The weight of each reference station in the hybrid strategy is determined by the (i) distance and (ii) elevation differences between the target farm site and each reference station. In this case, the wind data is divided into sectors according to the wind direction, and the MCP strategy is implemented for each wind direction sector separately. The applicability of the proposed hybrid strategy is investigated using five MCP methods: (i) the linear regression; (ii) the variance ratio; (iii) the Weibull scale; (iv) the artificial neural networks; and (v) the support vector regression. To implement the hybrid MCP methodology, we use hourly averaged wind data recorded at five stations in the state of Minnesota between 07-01-1996 and 06-30-2004. Three sets of performance metrics are used to evaluate the hybrid MCP method. The first set of metrics analyze the statistical performance, including the mean wind speed, wind speed variance, root mean square error, and mean absolute error. The second set of metrics evaluate the distribution of long-term wind speed; to this end, the Weibull distribution and the Multivariate and Multimodal Wind Distribution models are adopted. The third set of metrics analyze

  20. Erosion of wind turbine blade coatings - Design and analysis of jet-based laboratory equipment for performance evaluation

    DEFF Research Database (Denmark)

    Zhang, Shizhong; Dam-Johansen, Kim; Nørkjær, Sten

    2015-01-01

    of the blades in such equipment. To reduce expensive blade maintenance repairs and to avoid out-of-service periods, energy-absorbing blade coatings are required to protect rotor blades from rain erosion. In this work we describe the design, construction and evaluation of a laboratory setup for fast screening...... experimental blade coatings were investigated using the proposed experimental design. The evaluation of the coatings under conditions where impact frequency and water hammer pressure were "matched" could not be directly correlated with the results obtained with the whirling arm rig. This result may...

  1. Two Machine Learning Approaches for Short-Term Wind Speed Time-Series Prediction.

    Science.gov (United States)

    Ak, Ronay; Fink, Olga; Zio, Enrico

    2016-08-01

    The increasing liberalization of European electricity markets, the growing proportion of intermittent renewable energy being fed into the energy grids, and also new challenges in the patterns of energy consumption (such as electric mobility) require flexible and intelligent power grids capable of providing efficient, reliable, economical, and sustainable energy production and distribution. From the supplier side, particularly, the integration of renewable energy sources (e.g., wind and solar) into the grid imposes an engineering and economic challenge because of the limited ability to control and dispatch these energy sources due to their intermittent characteristics. Time-series prediction of wind speed for wind power production is a particularly important and challenging task, wherein prediction intervals (PIs) are preferable results of the prediction, rather than point estimates, because they provide information on the confidence in the prediction. In this paper, two different machine learning approaches to assess PIs of time-series predictions are considered and compared: 1) multilayer perceptron neural networks trained with a multiobjective genetic algorithm and 2) extreme learning machines combined with the nearest neighbors approach. The proposed approaches are applied for short-term wind speed prediction from a real data set of hourly wind speed measurements for the region of Regina in Saskatchewan, Canada. Both approaches demonstrate good prediction precision and provide complementary advantages with respect to different evaluation criteria.

  2. Formation of Valley Networks in a Cold and Icy Early Mars Climate: Predictions for Erosion Rates and Channel Morphology

    Science.gov (United States)

    Cassanelli, J.

    2017-12-01

    Mars is host to a diverse array of valley networks, systems of linear-to-sinuous depressions which are widely distributed across the surface and which exhibit branching patterns similar to the dendritic drainage patterns of terrestrial fluvial systems. Characteristics of the valley networks are indicative of an origin by fluvial activity, providing among the most compelling evidence for the past presence of flowing liquid water on the surface of Mars. Stratigraphic and crater age dating techniques suggest that the formation of the valley networks occurred predominantly during the early geologic history of Mars ( 3.7 Ga). However, whether the valley networks formed predominantly by rainfall in a relatively warm and wet early Mars climate, or by snowmelt and episodic rainfall in an ambient cold and icy climate, remains disputed. Understanding the formative environment of the valley networks will help distinguish between these warm and cold end-member early Mars climate models. Here we test a conceptual model for channel incision and evolution under cold and icy conditions with a substrate characterized by the presence of an ice-free dry active layer and subjacent ice-cemented regolith, similar to that found in the Antarctic McMurdo Dry Valleys. We implement numerical thermal models, quantitative erosion and transport estimates, and morphometric analyses in order to outline predictions for (1) the precise nature and structure of the substrate, (2) fluvial erosion/incision rates, and (3) channel morphology. Model predictions are compared against morphologic and morphometric observational data to evaluate consistency with the assumed cold climate scenario. In the cold climate scenario, the substrate is predicted to be characterized by a kilometers-thick globally-continuous cryosphere below a 50-100 meter thick desiccated ice-free zone. Initial results suggest that, with the predicted substrate structure, fluvial channel erosion and morphology in a cold early Mars

  3. Assessing the vegetation canopy influences on wind flow using wind ...

    Indian Academy of Sciences (India)

    Artificial plastic vegetations with different porosity and canopy shape were introduced as ... Wind erosion is the Aeolian process by which soil particles are detached from ..... the stabilizing role of vegetation on wind erosion. And therefore, for ...

  4. Calculation Methods of Topographic Factors Modification Using Data Digital Elevation Model (DEM To Predict Erosion

    Directory of Open Access Journals (Sweden)

    Hengki Simanjuntak

    2018-03-01

    Full Text Available Erosion  is a crucial information for sustainable management of land resources within a particular watershed. The information of erosion is needed for land resource management planning, and is generally counted by USLE (Universal Soil Loss Equation. One of the parameters in USLE is topographic factor (LS. The determinations of LS in erosion estimation model are vary, both in terms of LS factor equation, as well as in terms of the length of the slope (λ and slope (s measurements. There are at least 3 methods used to calculate slope factors in spatial operation, i.e (1 Input of the LS Value from Table (INT, (2 Flow accumulation, and (3 Cell Size. The study was designed to obtain a method of calculation that gives the smallest topographic factor and in order to obtain a LS factors that similar to the slope information. Research location in Kampa Sub watershed, The LS determination in Kampa Sub watershed basically are with (INT and without calculating λ and s. INT method is determination without calculating λ and s, LS value is generate from the contour map and DEM SRTM by giving LS value from table reference of LS value. The Flow Accumulation and Cell Size are determination of LS Value by calculating λ and s. The Flow Accumulation method modifies the determination of λ and s using the middle value of s, λ per land use, and λ and s per cell. Cell Size method determines λ using the amount of cell size. The results showed that the “cell size” and "INT" methods were the best method for topographic factor (LS calculation, because LS value of “cell size” and "INT" methods are smaller than the flow accumulation method and the LS value similar to the slope information. LS value from that methods generated weighted value in average of 0,55−0,58. Keywords: cell size, flow accumulation, flow direction, the length of the slope, USLE

  5. Predicting the Rate of River Bank Erosion Caused by Large Wood Log

    Science.gov (United States)

    Zhang, N.; Rutherfurd, I.; Ghisalberti, M.

    2016-12-01

    When a single tree falls into a river channel, flow is deflected and accelerated between the tree roots and the bank face, increasing shear stress and scouring the bank. The scallop shaped erosion increases the diversity of the channel morphology, but also causes concern for adjacent landholders. Concern about increased bank erosion is one of the main reasons for large wood to still be removed from channels in SE Australia. Further, the hydraulic effect of many logs in the channel can reduce overall bank erosion rates. Although both phenomena have been described before, this research develops a hydraulic model that estimates their magnitude, and tests and calibrates this model with flume and field measurements, with logs with various configurations and sizes. Specifically, the model estimates the change in excess shear stress on the bank associated . The model addresses the effect of the log angle, distance from bank, and log size and flow condition by solving the mass continuity and energy conservation between the cross section at the approaching flow and contracted flow. Then, we evaluate our model against flume experiment preformed with semi-realistic log models to represent logs in different sizes and decay stages by comparing the measured and simulated velocity increase in the gap between the log and the bank. The log angle, distance from bank, and flow condition are systemically varied for each log model during the experiment. Final, the calibrated model is compared with the field data collected in anabranching channels of Murray River in SE Australia where there are abundant instream logs and regulated and consistent high flow for irrigation. Preliminary results suggest that a log can significantly increase the shear stress on the bank, especially when it positions perpendicular to the flow. The shear stress increases with the log angle in a rising curve (The log angle is the angle between log trunk and flow direction. 0o means log is parallel to flow with

  6. Wind tunnel testing to predict control room atmospheric dispersion factors

    International Nuclear Information System (INIS)

    Holmquist, L.J.; Harden, P.A.; Muraida, J.E.

    1993-01-01

    Recent concerns at Palisades about control room habitability in the event of a loss-of-coolant accident have led to an extensive effort to increase control room habitability margin. The heating, ventilating and air-conditioning (HVAC) system servicing the control room has the potential for unfiltered in-leakage through its normal outside air intake louvered isolation dampers during emergency mode. The current limiting control room habitability analysis allows for 1.2 x 10 -2 m 3 /s (25 ft 3 /min) unfiltered in-leakage into the control room envelope. This leakage value was not thought to be achievable with the existing as-built configuration. Repairing the system was considered as a potential solution; however, this would be costly and could negatively affect plant operation. In addition, the system would still be required to meet the low specified unfiltered in-leakage. A second approach to this problem was to determine the atmospheric dispersion factors (x/Q's) through a wind tunnel test using a scale model of Palisades. The results of the wind tunnel testing could yield more realistic x/Q's for control room habitability than previously employed methods. Palisades selected the wind tunnel study option based on its ease of implementation, realistic results, and low cost. More importantly, the results of the study could increase the allowable unfiltered in-leakage

  7. Predicting Ionization Rates from SEP and Solar Wind Proton Precipitation into the Martian Atmosphere

    Science.gov (United States)

    Jolitz, R.; Dong, C.; Lee, C. O.; Curry, S.; Lillis, R. J.; Brain, D.; Halekas, J. S.; Larson, D. E.; Bougher, S. W.; Jakosky, B. M.

    2017-12-01

    Precipitating energetic particles ionize planetary atmospheres and increase total electron content. At Mars, the solar wind and solar energetic particles (SEPs) can precipitate directly into the atmosphere because solar wind protons can charge exchange to become neutrals and pass through the magnetosheath, while SEPs are sufficiently energetic to cross the magnetosheath unchanged. In this study we will present predicted ionization rates and resulting electron densities produced by solar wind and SEP proton ionization during nominal solar activity and a CME shock front impact event on May 16 2016. We will use the Atmospheric Scattering of Protons and Energetic Neutrals (ASPEN) model to compare ionization by SEP and solar wind protons currently measured by the SWIA (Solar Wind Ion Analyzer) and SEP instruments aboard the MAVEN spacecraft. Results will help to quantify how the ionosphere responds to extreme solar events during solar minimum.

  8. Combined Active and Reactive Power Control of Wind Farms based on Model Predictive Control

    DEFF Research Database (Denmark)

    Zhao, Haoran; Wu, Qiuwei; Wang, Jianhui

    2017-01-01

    This paper proposes a combined wind farm controller based on Model Predictive Control (MPC). Compared with the conventional decoupled active and reactive power control, the proposed control scheme considers the significant impact of active power on voltage variations due to the low X=R ratio...... of wind farm collector systems. The voltage control is improved. Besides, by coordination of active and reactive power, the Var capacity is optimized to prevent potential failures due to Var shortage, especially when the wind farm operates close to its full load. An analytical method is used to calculate...... the sensitivity coefficients to improve the computation efficiency and overcome the convergence problem. Two control modes are designed for both normal and emergency conditions. A wind farm with 20 wind turbines was used to verify the proposed combined control scheme....

  9. A prediction model for wind speed ratios at pedestrian level with simplified urban canopies

    Science.gov (United States)

    Ikegaya, N.; Ikeda, Y.; Hagishima, A.; Razak, A. A.; Tanimoto, J.

    2017-02-01

    The purpose of this study is to review and improve prediction models for wind speed ratios at pedestrian level with simplified urban canopies. We adopted an extensive database of velocity fields under various conditions for arrays consisting of cubes, slender or flattened rectangles, and rectangles with varying roughness heights. Conclusions are summarized as follows: first, a new geometric parameter is introduced as a function of the plan area index and the aspect ratio so as to express the increase in virtual density that causes wind speed reduction. Second, the estimated wind speed ratios in the range 0.05 coefficients between the wind speeds averaged over the entire region, and the front or side region values are larger than 0.8. In contrast, in areas where the influence of roughness elements is significant, such as behind a building, the wind speeds are weakly correlated.

  10. Bayesian state prediction of wind turbine bearing failure

    DEFF Research Database (Denmark)

    Herp, Jürgen; Ramezani, Mohammad H.; Bach-Andersen, Martin

    2017-01-01

    A statistical approach to abstract and predict turbine states in an online manner has been developed. Online inference is performed on temperature measurement residuals to predict the failure state δn steps ahead of time. In this framework a case study is performed showing the ability to predict...

  11. Prediction of the wind turbine performance by using BEM with airfoil data extracted from CFD

    DEFF Research Database (Denmark)

    Yang, Hua; Shen, Wen Zhong; Xu, Haoran

    2014-01-01

    Blade element momentum (BEM) theory with airfoil data is a widely used technique for prediction of wind turbine aerodynamic performance, but the reliability of the airfoil data is an important factor for the prediction accuracy of aerodynamic loads and power. The airfoil characteristics used in BEM...

  12. Wind Power Grid Connected Capacity Prediction Using LSSVM Optimized by the Bat Algorithm

    Directory of Open Access Journals (Sweden)

    Qunli Wu

    2015-12-01

    Full Text Available Given the stochastic nature of wind, wind power grid-connected capacity prediction plays an essential role in coping with the challenge of balancing supply and demand. Accurate forecasting methods make enormous contribution to mapping wind power strategy, power dispatching and sustainable development of wind power industry. This study proposes a bat algorithm (BA–least squares support vector machine (LSSVM hybrid model to improve prediction performance. In order to select input of LSSVM effectively, Stationarity, Cointegration and Granger causality tests are conducted to examine the influence of installed capacity with different lags, and partial autocorrelation analysis is employed to investigate the inner relationship of grid-connected capacity. The parameters in LSSVM are optimized by BA to validate the learning ability and generalization of LSSVM. Multiple model sufficiency evaluation methods are utilized. The research results reveal that the accuracy improvement of the present approach can reach about 20% compared to other single or hybrid models.

  13. A novel implementation of kNN classifier based on multi-tupled meteorological input data for wind power prediction

    International Nuclear Information System (INIS)

    Yesilbudak, Mehmet; Sagiroglu, Seref; Colak, Ilhami

    2017-01-01

    Highlights: • An accurate wind power prediction model is proposed for very short-term horizon. • The k-nearest neighbor classifier is implemented based on the multi-tupled inputs. • The variation of wind power prediction errors is evaluated in various aspects. • Our approach shows the superior prediction performance over the persistence method. - Abstract: With the growing share of wind power production in the electric power grids, many critical challenges to the grid operators have been emerged in terms of the power balance, power quality, voltage support, frequency stability, load scheduling, unit commitment and spinning reserve calculations. To overcome such problems, numerous studies have been conducted to predict the wind power production, but a small number of them have attempted to improve the prediction accuracy by employing the multidimensional meteorological input data. The novelties of this study lie in the proposal of an efficient and easy to implement very short-term wind power prediction model based on the k-nearest neighbor classifier (kNN), in the usage of wind speed, wind direction, barometric pressure and air temperature parameters as the multi-tupled meteorological inputs and in the comparison of wind power prediction results with respect to the persistence reference model. As a result of the achieved patterns, we characterize the variation of wind power prediction errors according to the input tuples, distance measures and neighbor numbers, and uncover the most influential and the most ineffective meteorological parameters on the optimization of wind power prediction results.

  14. Complex terrain wind resource estimation with the wind-atlas method: Prediction errors using linearized and nonlinear CFD micro-scale models

    DEFF Research Database (Denmark)

    Troen, Ib; Bechmann, Andreas; Kelly, Mark C.

    2014-01-01

    Using the Wind Atlas methodology to predict the average wind speed at one location from measured climatological wind frequency distributions at another nearby location we analyse the relative prediction errors using a linearized flow model (IBZ) and a more physically correct fully non-linear 3D...... flow model (CFD) for a number of sites in very complex terrain (large terrain slopes). We first briefly describe the Wind Atlas methodology as implemented in WAsP and the specifics of the “classical” model setup and the new setup allowing the use of the CFD computation engine. We discuss some known...

  15. A New Global Regression Analysis Method for the Prediction of Wind Tunnel Model Weight Corrections

    Science.gov (United States)

    Ulbrich, Norbert Manfred; Bridge, Thomas M.; Amaya, Max A.

    2014-01-01

    A new global regression analysis method is discussed that predicts wind tunnel model weight corrections for strain-gage balance loads during a wind tunnel test. The method determines corrections by combining "wind-on" model attitude measurements with least squares estimates of the model weight and center of gravity coordinates that are obtained from "wind-off" data points. The method treats the least squares fit of the model weight separate from the fit of the center of gravity coordinates. Therefore, it performs two fits of "wind- off" data points and uses the least squares estimator of the model weight as an input for the fit of the center of gravity coordinates. Explicit equations for the least squares estimators of the weight and center of gravity coordinates are derived that simplify the implementation of the method in the data system software of a wind tunnel. In addition, recommendations for sets of "wind-off" data points are made that take typical model support system constraints into account. Explicit equations of the confidence intervals on the model weight and center of gravity coordinates and two different error analyses of the model weight prediction are also discussed in the appendices of the paper.

  16. Predictive control of a chaotic permanent magnet synchronous generator in a wind turbine system

    International Nuclear Information System (INIS)

    Messadi, Manal; Mellit, Adel; Kemih, Karim; Ghanes, Malek

    2015-01-01

    This paper investigates how to address the chaos problem in a permanent magnet synchronous generator (PMSG) in a wind turbine system. Predictive control approach is proposed to suppress chaotic behavior and make operating stable; the advantage of this method is that it can only be applied to one state of the wind turbine system. The use of the genetic algorithms to estimate the optimal parameter values of the wind turbine leads to maximization of the power generation. Moreover, some simulation results are included to visualize the effectiveness and robustness of the proposed method. (paper)

  17. Predictive control of a chaotic permanent magnet synchronous generator in a wind turbine system

    Science.gov (United States)

    Manal, Messadi; Adel, Mellit; Karim, Kemih; Malek, Ghanes

    2015-01-01

    This paper investigates how to address the chaos problem in a permanent magnet synchronous generator (PMSG) in a wind turbine system. Predictive control approach is proposed to suppress chaotic behavior and make operating stable; the advantage of this method is that it can only be applied to one state of the wind turbine system. The use of the genetic algorithms to estimate the optimal parameter values of the wind turbine leads to maximization of the power generation. Moreover, some simulation results are included to visualize the effectiveness and robustness of the proposed method. Project supported by the CMEP-TASSILI Project (Grant No. 14MDU920).

  18. Assessing Long-Term Wind Conditions by Combining Different Measure-Correlate-Predict Algorithms: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, J.; Chowdhury, S.; Messac, A.; Hodge, B. M.

    2013-08-01

    This paper significantly advances the hybrid measure-correlate-predict (MCP) methodology, enabling it to account for variations of both wind speed and direction. The advanced hybrid MCP method uses the recorded data of multiple reference stations to estimate the long-term wind condition at a target wind plant site. The results show that the accuracy of the hybrid MCP method is highly sensitive to the combination of the individual MCP algorithms and reference stations. It was also found that the best combination of MCP algorithms varies based on the length of the correlation period.

  19. Using Unsupervised Machine Learning for Outlier Detection in Data to Improve Wind Power Production Prediction

    OpenAIRE

    Åkerberg, Ludvig

    2017-01-01

    The expansion of wind power for electrical energy production has increased in recent years and shows no signs of slowing down. This unpredictable source of energy has contributed to destabilization of the electrical grid causing the energy market prices to vary significantly on a daily basis. For energy producers and consumers to make good investments, methods have been developed to make predictions of wind power production. These methods are often based on machine learning were historical we...

  20. A Free Wake Numerical Simulation for Darrieus Vertical Axis Wind Turbine Performance Prediction

    Science.gov (United States)

    Belu, Radian

    2010-11-01

    In the last four decades, several aerodynamic prediction models have been formulated for the Darrieus wind turbine performances and characteristics. We can identified two families: stream-tube and vortex. The paper presents a simplified numerical techniques for simulating vertical axis wind turbine flow, based on the lifting line theory and a free vortex wake model, including dynamic stall effects for predicting the performances of a 3-D vertical axis wind turbine. A vortex model is used in which the wake is composed of trailing stream-wise and shedding span-wise vortices, whose strengths are equal to the change in the bound vortex strength as required by the Helmholz and Kelvin theorems. Performance parameters are computed by application of the Biot-Savart law along with the Kutta-Jukowski theorem and a semi-empirical stall model. We tested the developed model with an adaptation of the earlier multiple stream-tube performance prediction model for the Darrieus turbines. Predictions by using our method are shown to compare favorably with existing experimental data and the outputs of other numerical models. The method can predict accurately the local and global performances of a vertical axis wind turbine, and can be used in the design and optimization of wind turbines for built environment applications.

  1. Causes of bat fatalities at wind turbines: Hypotheses and predictions

    Science.gov (United States)

    Cryan, P.M.; Barclay, R.M.R.

    2009-01-01

    Thousands of industrial-scale wind turbines are being built across the world each year to meet the growing demand for sustainable energy. Bats of certain species are dying at wind turbines in unprecedented numbers. Species of bats consistently affected by turbines tend to be those that rely on trees as roosts and most migrate long distances. Although considerable progress has been made in recent years toward better understanding the problem, the causes of bat fatalities at turbines remain unclear. In this synthesis, we review hypothesized causes of bat fatalities at turbines. Hypotheses of cause fall into 2 general categoriesproximate and ultimate. Proximate causes explain the direct means by which bats die at turbines and include collision with towers and rotating blades, and barotrauma. Ultimate causes explain why bats come close to turbines and include 3 general types: random collisions, coincidental collisions, and collisions that result from attraction of bats to turbines. The random collision hypothesis posits that interactions between bats and turbines are random events and that fatalities are representative of the bats present at a site. Coincidental hypotheses posit that certain aspects of bat distribution or behavior put them at risk of collision and include aggregation during migration and seasonal increases in flight activity associated with feeding or mating. A surprising number of attraction hypotheses suggest that bats might be attracted to turbines out of curiosity, misperception, or as potential feeding, roosting, flocking, and mating opportunities. Identifying, prioritizing, and testing hypothesized causes of bat collisions with wind turbines are vital steps toward developing practical solutions to the problem. ?? 2009 American Society of Mammalogists.

  2. Wind power application research on the fusion of the determination and ensemble prediction

    Science.gov (United States)

    Lan, Shi; Lina, Xu; Yuzhu, Hao

    2017-07-01

    The fused product of wind speed for the wind farm is designed through the use of wind speed products of ensemble prediction from the European Centre for Medium-Range Weather Forecasts (ECMWF) and professional numerical model products on wind power based on Mesoscale Model5 (MM5) and Beijing Rapid Update Cycle (BJ-RUC), which are suitable for short-term wind power forecasting and electric dispatch. The single-valued forecast is formed by calculating the different ensemble statistics of the Bayesian probabilistic forecasting representing the uncertainty of ECMWF ensemble prediction. Using autoregressive integrated moving average (ARIMA) model to improve the time resolution of the single-valued forecast, and based on the Bayesian model averaging (BMA) and the deterministic numerical model prediction, the optimal wind speed forecasting curve and the confidence interval are provided. The result shows that the fusion forecast has made obvious improvement to the accuracy relative to the existing numerical forecasting products. Compared with the 0-24 h existing deterministic forecast in the validation period, the mean absolute error (MAE) is decreased by 24.3 % and the correlation coefficient (R) is increased by 12.5 %. In comparison with the ECMWF ensemble forecast, the MAE is reduced by 11.7 %, and R is increased 14.5 %. Additionally, MAE did not increase with the prolongation of the forecast ahead.

  3. Adapting SWAT hillslope erosion model to predict sediment concentrations and yields in large Basins.

    Science.gov (United States)

    Vigiak, Olga; Malagó, Anna; Bouraoui, Fayçal; Vanmaercke, Matthias; Poesen, Jean

    2015-12-15

    The Soil and Water Assessment Tool (SWAT) is used worldwide for water quality assessment and planning. This paper aimed to assess and adapt SWAT hillslope sediment yield model (Modified Universal Soil Loss Equation, MUSLE) for applications in large basins, i.e. when spatial data is coarse and model units are large; and to develop a robust sediment calibration method for large regions. The Upper Danube Basin (132,000km(2)) was used as case study representative of large European Basins. The MUSLE was modified to reduce sensitivity of sediment yields to the Hydrologic Response Unit (HRU) size, and to identify appropriate algorithms for estimating hillslope length (L) and slope-length factor (LS). HRUs gross erosion was broadly calibrated against plot data and soil erosion map estimates. Next, mean annual SWAT suspended sediment concentrations (SSC, mg/L) were calibrated and validated against SSC data at 55 gauging stations (622 station-years). SWAT annual specific sediment yields in subbasin reaches (RSSY, t/km(2)/year) were compared to yields measured at 33 gauging stations (87station-years). The best SWAT configuration combined a MUSLE equation modified by the introduction of a threshold area of 0.01km(2) where L and LS were estimated with flow accumulation algorithms. For this configuration, the SSC residual interquartile was less than +/-15mg/L both for the calibration (1995-2004) and the validation (2005-2009) periods. The mean SSC percent bias for 1995-2009 was 24%. RSSY residual interquartile was within +/-10t/km(2)/year, with a mean RSSY percent bias of 12%. Residuals showed no bias with respect to drainage area, slope, or spatial distribution. The use of multiple data types at multiple sites enabled robust simulation of sediment concentrations and yields of the region. The MUSLE modifications are recommended for use in large basins. Based on SWAT simulations, we present a sediment budget for the Upper Danube Basin. Copyright © 2015. Published by Elsevier B.V.

  4. Precision comparison of the erosion rates derived from 137Cs measurements models with predictions based on empirical relationship

    International Nuclear Information System (INIS)

    Yang Mingyi; Liu Puling; Li Liqing

    2004-01-01

    The soil samples were collected in 6 cultivated runoff plots with grid sampling method, and the soil erosion rates derived from 137 Cs measurements were calculated. The models precision of Zhang Xinbao, Zhou Weizhi, Yang Hao and Walling were compared with predictions based on empirical relationship, data showed that the precision of 4 models is high within 50m slope length except for the slope with low slope angle and short length. Relatively, the precision of Walling's model is better than that of Zhang Xinbao, Zhou Weizhi and Yang Hao. In addition, the relationship between parameter Γ in Walling's improved model and slope angle was analyzed, the ralation is: Y=0.0109 X 1.0072 . (authors)

  5. Rill erosion rates in burned forests

    Science.gov (United States)

    Joseph W. Wagenbrenner; Peter R. Robichaud

    2011-01-01

    Introduction Wildfires often produce large increases in runoff and erosion rates (e.g., Moody and Martin, 2009), and land managers need to predict the frequency and magnitude of postfire erosion to determine the needs for hazard response and possible erosion mitigation to reduce the impacts of increased erosion on public safety and valued resources. The Water Erosion...

  6. Kinetic and Potential Sputtering Enhancements of Lunar Regolith Erosion: The Contribution of the Heavy Multicharged (Minority) Solar Wind Constituents

    Science.gov (United States)

    Meyer, F. W.; Barghouty, A. F.

    2012-01-01

    We report preliminary results for H+, Ar+1, Ar+6 and Ar+9 ion sputtering of JSC-1A lunar regolith simulant at solar wind velocities, obtain ed at the ORNL Multicharged Ion Research Facility using quadrupole ma ss spectrometry. The multi-charged Ar ions were used as proxies for i ntermediate mass solar wind multicharged ions. Prior to the Ar beam e xposures, the sample was exposed to high fluence H+ irradiation to si mulate H-loading due to the dominant solar wind constituent. A x80 en hancement of oxygen sputtering by Ar+ over same velocity H+ was measu red and an additional x2 increase for Ar+9 over same velocity Ar+ was demonstrated, giving clear evidence of the importance of potential s puttering by multicharged ions. This enhancement was observed to pers ist to the maximum fluences investigated (approx 10(exp 16)/sq cm). As discussed in a companion abstract by N. Barghouty, such persistent s puttering enhancement has significant implications on weathering and aging of lunar regolith. In addition, XPS measurements showed strong evidence of Fe reduction for those target areas that had been exposed to high fluence Ar+ and Ar+8 beams. Preferential oxidation of the Fe -reduced beam-exposed regions during transfer to the XPS system led t o enhanced O concentrations in those regions as well. On the basis of these very promising preliminary results, a NASA-LASER project on mo re extensive measurements was recently selected for funding. The prop osal expands the collaboration with NASA-MSFC for the simulation effort, and adds a new collaboration with NASA-GSFC for lunar mission-rele vant measurements.

  7. Evaluation of the rusle and disturbed wepp erosion models for predicting soil loss in the first year after wildfire in NW Spain.

    Science.gov (United States)

    Fernández, Cristina; Vega, José A

    2018-05-04

    Severe fire greatly increases soil erosion rates and overland-flow in forest land. Soil erosion prediction models are essential for estimating fire impacts and planning post-fire emergency responses. We evaluated the performance of a) the Revised Universal Soil Loss Equation (RUSLE), modified by inclusion of an alternative equation for the soil erodibility factor, and b) the Disturbed WEPP model, by comparing the soil loss predicted by the models and the soil loss measured in the first year after wildfire in 44 experimental field plots in NW Spain. The Disturbed WEPP has not previously been validated with field data for use in NW Spain; validation studies are also very scarce in other areas. We found that both models underestimated the erosion rates. The accuracy of the RUSLE model was low, even after inclusion of a modified soil erodibility factor accounting for high contents of soil organic matter. We conclude that neither model is suitable for predicting soil erosion in the first year after fire in NW Spain and suggest that soil burn severity should be given greater weighting in post-fire soil erosion modelling. Copyright © 2018 Elsevier Inc. All rights reserved.

  8. Wind turbine control and model predictive control for uncertain systems

    DEFF Research Database (Denmark)

    Thomsen, Sven Creutz

    as disturbance models for controller design. The theoretical study deals with Model Predictive Control (MPC). MPC is an optimal control method which is characterized by the use of a receding prediction horizon. MPC has risen in popularity due to its inherent ability to systematically account for time...

  9. Comparison of measured and predicted airfoil self-noise with application to wind turbine noise reduction

    International Nuclear Information System (INIS)

    Dassen, T.; Parchen, R.; Guidati, G.; Wagner, S.; Kang, S.; Khodak, A.E.

    1998-01-01

    In the ongoing JOULE-III project 'Development of Design Tools for Reduced Aerodynamic Noise Wind Turbines (DRAW)', prediction codes for inflow-turbulence (IT) noise and turbulent boundary layer trailing-edge (TE) noise, are developed and validated. It is shown that the differences in IT noise radiation between airfoils having a different shape, are correctly predicted. The first, preliminary comparison made between predicted and measured TE noise spectra yields satisfactory results. 17 refs

  10. Verification of some numerical models for operationally predicting mesoscale winds aloft

    International Nuclear Information System (INIS)

    Cornett, J.S.; Randerson, D.

    1977-01-01

    Four numerical models are described for predicting mesoscale winds aloft for a 6 h period. These models are all tested statistically against persistence as the control forecast and against predictions made by operational forecasters. Mesoscale winds aloft data were used to initialize the models and to verify the predictions on an hourly basis. The model yielding the smallest root-mean-square vector errors (RMSVE's) was the one based on the most physics which included advection, ageostrophic acceleration, vertical mixing and friction. Horizontal advection was found to be the most important term in reducing the RMSVE's followed by ageostrophic acceleration, vertical advection, surface friction and vertical mixing. From a comparison of the mean absolute errors based on up to 72 independent wind-profile predictions made by operational forecasters, by the most complete model, and by persistence, we conclude that the model is the best wind predictor in the free air. In the boundary layer, the results tend to favor the forecaster for direction predictions. The speed predictions showed no overall superiority in any of these three models

  11. Aero-acoustic noise of wind turbines. Noise prediction models

    Energy Technology Data Exchange (ETDEWEB)

    Maribo Pedersen, B. [ed.

    1997-12-31

    Semi-empirical and CAA (Computational AeroAcoustics) noise prediction techniques are the subject of this expert meeting. The meeting presents and discusses models and methods. The meeting may provide answers to the following questions: What Noise sources are the most important? How are the sources best modeled? What needs to be done to do better predictions? Does it boil down to correct prediction of the unsteady aerodynamics around the rotor? Or is the difficult part to convert the aerodynamics into acoustics? (LN)

  12. Prediction of Typhoon Wind Speeds under Global Warming Conditions

    International Nuclear Information System (INIS)

    Choun, Young Sun; Kim, Min Kyu; Kang, Ju Whan; Kim, Yang Seon

    2016-01-01

    The continuous increase of SST by global warming conditions in the western North Pacific Ocean results in an increased occurrence of supertyphoons in East Asia and the Korean Peninsula. Recent numerical experiments have found that the central pressures of two historical typhoons, Maemi (2003) and Rusa (2002), which recorded the highest storm surges along the coasts of the Korean Peninsula, dropped about 19 and 17 hPa, respectively, when considering the future SST (a warming of 3.9 .deg. C for 100 years) over the East China Sea. The maximum wind speeds increase under global warming conditions. The probability of occurrence of super-typhoons increases in the future. The estimated return period for supertyphoons affecting the Younggwang site is about 1,000,000 years.

  13. Prediction of Typhoon Wind Speeds under Global Warming Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Choun, Young Sun; Kim, Min Kyu [KAERI, Daejeon (Korea, Republic of); Kang, Ju Whan; Kim, Yang Seon [Mokpo National University, Muan (Korea, Republic of)

    2016-05-15

    The continuous increase of SST by global warming conditions in the western North Pacific Ocean results in an increased occurrence of supertyphoons in East Asia and the Korean Peninsula. Recent numerical experiments have found that the central pressures of two historical typhoons, Maemi (2003) and Rusa (2002), which recorded the highest storm surges along the coasts of the Korean Peninsula, dropped about 19 and 17 hPa, respectively, when considering the future SST (a warming of 3.9 .deg. C for 100 years) over the East China Sea. The maximum wind speeds increase under global warming conditions. The probability of occurrence of super-typhoons increases in the future. The estimated return period for supertyphoons affecting the Younggwang site is about 1,000,000 years.

  14. Erosion and erosion-corrosion

    International Nuclear Information System (INIS)

    Isomoto, Yoshinori

    2008-01-01

    It is very difficult to interpret the technical term of erosion-corrosion' which is sometimes encountered in piping systems of power plants, because of complicated mechanisms and several confusing definitions of erosion-corrosion phenomena. 'FAC (flow accelerated corrosion)' is recently introduced as wall thinning of materials in power plant systems, as a representative of 'erosion-corrosion'. FAC is, however, not necessarily well understood and compared with erosion-corrosion. This paper describes firstly the origin, definition and fundamental understandings of erosion and erosion-corrosion, in order to reconsider and reconfirm the phenomena of erosion, erosion-corrosion and FAC. Next, typical mapping of erosion, corrosion, erosion-corrosion and FAC are introduced in flow velocity and environmental corrosiveness axes. The concept of damage rate in erosion-corrosion is finally discussed, connecting dissolution rate, mass transfer of metal ions in a metal oxide film and film growth. (author)

  15. Wind Resource Assessment in Complex Terrain with a High-Resolution Numerical Weather Prediction Model

    Science.gov (United States)

    Gruber, Karin; Serafin, Stefano; Grubišić, Vanda; Dorninger, Manfred; Zauner, Rudolf; Fink, Martin

    2014-05-01

    , considering the frequency of wind speed between cut-in and cut-out speed and of winds with a low vertical velocity component only. Wind turbines do not turn on at wind speeds below cut-in speed. Wind turbines are taken off from the generator in the case of wind speeds higher than cut-out speed and inclination angles of the wind vector greater than 8o. All of these parameters were computed at each model grid point in the innermost domain in order to map their spatial variability. The results show that in complex terrain the annual mean wind speed at hub height is not sufficient to predict the capacity factor of a turbine; vertical wind speed and the frequency of horizontal wind speed out of the range of cut-in and cut-out speed contribute substantially to a reduction of the energy harvest and locally high turbulence may considerably raise the building costs.

  16. Wind gust estimation by combining numerical weather prediction model and statistical post-processing

    Science.gov (United States)

    Patlakas, Platon; Drakaki, Eleni; Galanis, George; Spyrou, Christos; Kallos, George

    2017-04-01

    The continuous rise of off-shore and near-shore activities as well as the development of structures, such as wind farms and various offshore platforms, requires the employment of state-of-the-art risk assessment techniques. Such analysis is used to set the safety standards and can be characterized as a climatologically oriented approach. Nevertheless, a reliable operational support is also needed in order to minimize cost drawbacks and human danger during the construction and the functioning stage as well as during maintenance activities. One of the most important parameters for this kind of analysis is the wind speed intensity and variability. A critical measure associated with this variability is the presence and magnitude of wind gusts as estimated in the reference level of 10m. The latter can be attributed to different processes that vary among boundary-layer turbulence, convection activities, mountain waves and wake phenomena. The purpose of this work is the development of a wind gust forecasting methodology combining a Numerical Weather Prediction model and a dynamical statistical tool based on Kalman filtering. To this end, the parameterization of Wind Gust Estimate method was implemented to function within the framework of the atmospheric model SKIRON/Dust. The new modeling tool combines the atmospheric model with a statistical local adaptation methodology based on Kalman filters. This has been tested over the offshore west coastline of the United States. The main purpose is to provide a useful tool for wind analysis and prediction and applications related to offshore wind energy (power prediction, operation and maintenance). The results have been evaluated by using observational data from the NOAA's buoy network. As it was found, the predicted output shows a good behavior that is further improved after the local adjustment post-process.

  17. Adjoint-based model predictive control of wind farms : Beyond the quasi steady-state power maximization

    NARCIS (Netherlands)

    Vali, M.; Petrović, Vlaho; Boersma, S.; van Wingerden, J.W.; Kuhn, Martin; Dochain, Denis; Henrion, Didier; Peaucelle, Dimitri

    2017-01-01

    In this paper, we extend our closed-loop optimal control framework for wind farms to minimize wake-induced power losses. We develop an adjoint-based model predictive controller which employs a medium-fidelity 2D dynamic wind farm model. The wind turbine axial induction factors are considered here

  18. Bayesian based Prognostic Model for Predictive Maintenance of Offshore Wind Farms

    DEFF Research Database (Denmark)

    Asgarpour, Masoud; Sørensen, John Dalsgaard

    2018-01-01

    The operation and maintenance costs of offshore wind farms can be significantly reduced if existing corrective actions are performed as efficient as possible and if future corrective actions are avoided by performing sufficient preventive actions. In this paper a prognostic model for degradation...... monitoring, fault prediction and predictive maintenance of offshore wind components is defined. The diagnostic model defined in this paper is based on degradation, remaining useful lifetime and hybrid inspection threshold models. The defined degradation model is based on an exponential distribution...

  19. Bayesian based Prognostic Model for Predictive Maintenance of Offshore Wind Farms

    DEFF Research Database (Denmark)

    Asgarpour, Masoud; Sørensen, John Dalsgaard

    2018-01-01

    monitoring, fault prediction and predictive maintenance of offshore wind components is defined. The diagnostic model defined in this paper is based on degradation, remaining useful lifetime and hybrid inspection threshold models. The defined degradation model is based on an exponential distribution......The operation and maintenance costs of offshore wind farms can be significantly reduced if existing corrective actions are performed as efficient as possible and if future corrective actions are avoided by performing sufficient preventive actions. In this paper a prognostic model for degradation...

  20. Discussion of “Prediction intervals for short-term wind farm generation forecasts” and “Combined nonparametric prediction intervals for wind power generation”

    DEFF Research Database (Denmark)

    Pinson, Pierre; Tastu, Julija

    2014-01-01

    A new score for the evaluation of interval forecasts, the so-called coverage width-based criterion (CWC), was proposed and utilized.. This score has been used for the tuning (in-sample) and genuine evaluation (out-ofsample) of prediction intervals for various applications, e.g., electric load [1......], electricity prices [2], general purpose prediction [3], and wind power generation [4], [5]. Indeed, two papers by the same authors appearing in the IEEE Transactions On Sustainable Energy employ that score and use it to conclude on the comparative quality of alternative approaches to interval forecasting...

  1. Heartburn Severity Does Not Predict Disease Severity in Patients With Erosive Esophagitis

    Science.gov (United States)

    Fennerty, M. Brian; Johnson, David A.

    2006-01-01

    Background For patients with gastroesophageal reflux disease (GERD), it is often assumed by treating physicians that the severity of heartburn correlates with the severity of erosive esophagitis (EE). Objective This is a post hoc analysis of data from 5 clinical trials that investigate the relationship between the baseline severity of heartburn and the baseline severity of EE. Methods Patients with endoscopically confirmed EE were assessed for heartburn symptoms with a 4-point scale at baseline and during treatment for 8 weeks with various proton pump inhibitors in 5 double-blind trials in which esomeprazole was the common comparator. EE was graded with the Los Angeles (LA) classification system. In these trials, healing and symptom response were evaluated by endoscopy and questionnaire after 4 weeks of treatment. Patients who were not healed were treated for an additional 4 weeks and reevaluated. Results A total of 11,945 patients with endoscopically confirmed EE participated in the 5 trials, with patients receiving esomeprazole 40 mg (n = 5068), esomeprazole 20 mg (n = 1243), omeprazole 20 mg (n = 3018), or lansoprazole 30 mg (n = 2616). Approximately one quarter of the 11,945 GERD patients in these 5 trials had severe EE (defined as LA grades C or D), regardless of their baseline heartburn severity. Conclusion The severity of GERD symptoms does not correlate well with disease severity. These findings indicate that endoscopy may have value in GERD patients in identifying those with EE, and if empirical therapy is chosen, then longer courses (4-8 weeks) of antisecretory therapy may be necessary to ensure healing of unrecognized esophagitis. PMID:16926745

  2. Model predictive control of PMSG-based wind turbines for frequency regulation in an isolated grid

    DEFF Research Database (Denmark)

    Wang, Haixin; Yang, Junyou; Ma, Yiming

    2017-01-01

    This paper proposes a frequency regulation strategy applied to wind turbine generators (WTGs) in an isolated grid. In order to complement active power shortage caused by sudden load or wind speed change, an improved deloading method is proposed to solve inconsistent regulation capabilities...... in different speed regions and provide WTGs a certain capacity of power reserves. Considering the torque compensation may bring about power oscillation, speed reference of conventional pitch control system should be reset. Moreover, to suppress disturbances of load and wind speed as well as overcome dependence...... on system parameters, a model predictive controller (MPC) of wind farm is designed to generate torque compensation for each deloaded WTG. The key feature of this strategy is that each WTG reacts to grid disturbances in different ways, which depends on generator speeds. Hardware-in-the-loop simulation...

  3. Wind field near complex terrain using numerical weather prediction model

    Science.gov (United States)

    Chim, Kin-Sang

    The PennState/NCAR MM5 model was modified to simulate an idealized flow pass through a 3D obstacle in the Micro- Alpha Scale domain. The obstacle used were the idealized Gaussian obstacle and the real topography of Lantau Island of Hong Kong. The Froude number under study is ranged from 0.22 to 1.5. Regime diagrams for both the idealized Gaussian obstacle and Lantau island were constructed. This work is divided into five parts. The first part is the problem definition and the literature review of the related publications. The second part briefly discuss as the PennState/NCAR MM5 model and a case study of long- range transport is included. The third part is devoted to the modification and the verification of the PennState/NCAR MM5 model on the Micro-Alpha Scale domain. The implementation of the Orlanski (1976) open boundary condition is included with the method of single sounding initialization of the model. Moreover, an upper dissipative layer, Klemp and Lilly (1978), is implemented on the model. The simulated result is verified by the Automatic Weather Station (AWS) data and the Wind Profiler data. Four different types of Planetary Boundary Layer (PBL) parameterization schemes have been investigated in order to find out the most suitable one for Micro-Alpha Scale domain in terms of both accuracy and efficiency. Bulk Aerodynamic type of PBL parameterization scheme is found to be the most suitable PBL parameterization scheme. Investigation of the free- slip lower boundary condition is performed and the simulated result is compared with that with friction. The fourth part is the use of the modified PennState/NCAR MM5 model for an idealized flow simulation. The idealized uniform flow used is nonhydrostatic and has constant Froude number. Sensitivity test is performed by varying the Froude number and the regime diagram is constructed. Moreover, nondimensional drag is found to be useful for regime identification. The model result is also compared with the analytic

  4. A Gaussian process regression based hybrid approach for short-term wind speed prediction

    International Nuclear Information System (INIS)

    Zhang, Chi; Wei, Haikun; Zhao, Xin; Liu, Tianhong; Zhang, Kanjian

    2016-01-01

    Highlights: • A novel hybrid approach is proposed for short-term wind speed prediction. • This method combines the parametric AR model with the non-parametric GPR model. • The relative importance of different inputs is considered. • Different types of covariance functions are considered and combined. • It can provide both accurate point forecasts and satisfactory prediction intervals. - Abstract: This paper proposes a hybrid model based on autoregressive (AR) model and Gaussian process regression (GPR) for probabilistic wind speed forecasting. In the proposed approach, the AR model is employed to capture the overall structure from wind speed series, and the GPR is adopted to extract the local structure. Additionally, automatic relevance determination (ARD) is used to take into account the relative importance of different inputs, and different types of covariance functions are combined to capture the characteristics of the data. The proposed hybrid model is compared with the persistence model, artificial neural network (ANN), and support vector machine (SVM) for one-step ahead forecasting, using wind speed data collected from three wind farms in China. The forecasting results indicate that the proposed method can not only improve point forecasts compared with other methods, but also generate satisfactory prediction intervals.

  5. Fuels planning: science synthesis and integration; environmental consequences fact sheet 12: Water Erosion Prediction Project (WEPP) Fuel Management (FuMe) tool

    Science.gov (United States)

    William Elliot; David Hall

    2005-01-01

    The Water Erosion Prediction Project (WEPP) Fuel Management (FuMe) tool was developed to estimate sediment generated by fuel management activities. WEPP FuMe estimates sediment generated for 12 fuel-related conditions from a single input. This fact sheet identifies the intended users and uses, required inputs, what the model does, and tells the user how to obtain the...

  6. Identifying the Areas Benefitting from the Prevention of Wind Erosion by the Key Ecological Function Area for the Protection of Desertification in Hunshandake, China

    Directory of Open Access Journals (Sweden)

    Yu Xiao

    2017-10-01

    Full Text Available Research on the spatial flow of ecosystem services can help to identify the spatial relationships between service-providing areas (SPAs and service-benefitting areas (SBAs. In this study, we used the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT model to stimulate the flow paths of the wind erosion prevented by ecosystems in Hunshandake, China. By interpolating these paths, the SBAs were identified, and their benefits in terms of land cover, population, and Gross Domestic Product (GDP were determined. The results indicated that the flow paths mostly extended to the eastern part of the study area, and the estimated cover of the SBAs was 39.21% of the total area of China. The grid cells through which many (≥10% of the trajectories passed were mainly located in the western part of north-eastern China and the eastern part of northern China. The benefitting population accounted for 74.51% of the total population of China, and the GDP was 67.11% of the total in 2010. Based on this research, we described a quantitative relationship between the SPAs and the SBAs and identified the actual beneficiaries. This work may provide scientific knowledge that can be used by decision makers to develop management strategies, such as ecological compensation to mitigate damage from sandstorms in the study area.

  7. Predicting the Extreme Loads on a Wind Turbine Considering Uncertainty in Airfoil Data

    DEFF Research Database (Denmark)

    Abdallah, Imad; Natarajan, Anand; Sørensen, John Dalsgaard

    2014-01-01

    The sources contributing to uncertainty in a wind turbine blade static airfoil data include wind tunnel testing, CFD calculations, 3D rotational corrections based on CFD or emprircal models, surface roughness corrections, Reynolds number corrections, expansion to the full 360-degree angle of attack...... range, validation by full scale measurements, and geometric distortions of the blade during manufacturing and under loading. In this paper a stochastic model of the static airfoil data is proposed to supplement the prediction of extreme loads effects for large wind turbines. It is shown...... that the uncertainty in airfoil data can have e significant impact on the prediction of extreme loads effects depending on the component, and the correlation along the span of the blade....

  8. MRI of the wrist and finger joints in inflammatory joint diseases at 1-year interval: MRI features to predict bone erosions

    International Nuclear Information System (INIS)

    Savnik, Anette; Malmskov, Hanne; Graff, Lykke B.; Danneskiold-Samsoee, Bente; Bliddal, Henning; Thomsen, Henrik S.; Nielsen, Henrik; Boesen, Jens

    2002-01-01

    The aim of this study was to assess the ability of MRI determined synovial volumes and bone marrow oedema to predict progressions in bone erosions after 1 year in patients with different types of inflammatory joint diseases. Eighty-four patients underwent MRI, laboratory and clinical examination at baseline and 1 year later. Magnetic resonance imaging of the wrist and finger joints was performed in 22 patients with rheumatoid arthritis less than 3 years (group 1) who fulfilled the American College of Rheumatology (ACR) criteria for rheumatoid arthritis, 18 patients with reactive arthritis or psoriatic arthritis (group 2), 22 patients with more than 3 years duration of rheumatoid arthritis, who fulfilled the ACR criteria for rheumatoid arthritis (group 3), and 20 patients with arthralgia (group 4). The volume of the synovial membrane was outlined manually before and after gadodiamide injection on the T1-weighted sequences in the finger joints. Bones with marrow oedema were summed up in the wrist and fingers on short-tau inversion recovery sequences. These MRI features was compared with the number of bone erosions 1 year later. The MR images were scored independently under masked conditions. The synovial volumes in the finger joints assessed on pre-contrast images was highly predictive of bone erosions 1 year later in patients with rheumatoid arthritis (groups 1 and 3). The strongest individual predictor of bone erosions at 1-year follow-up was bone marrow oedema, if present at the wrist at baseline. Bone erosions on baseline MRI were in few cases reversible at follow-up MRI. The total synovial volume in the finger joints, and the presence of bone oedema in the wrist bones, seems to be predictive for the number of bone erosions 1 year later and may be used in screening. The importance of very early bone changes on MRI and the importance of the reversibility of these findings remain to be clarified. (orig.)

  9. Predicting local distributions of erosion-corrosion wear sites for the piping in the nuclear power plant using CFD models

    International Nuclear Information System (INIS)

    Ferng, Y.M.

    2008-01-01

    The erosion-corrosion (E/C) wear is an essential degradation mechanism for the piping in the nuclear power plant, which results in the oxide mass loss from the inside of piping, the wall thinning, and even the pipe break. The pipe break induced by the E/C wear may cause costly plant repairs and personal injures. The measurement of pipe wall thickness is a useful tool for the power plant to prevent this incident. In this paper, CFD models are proposed to predict the local distributions of E/C wear sites, which include both the two-phase hydrodynamic model and the E/C models. The impacts of centrifugal and gravitational forces on the liquid droplet behaviors within the piping can be reasonably captured by the two-phase model. Coupled with these calculated flow characteristics, the E/C models can predicted the wear site distributions that show satisfactory agreement with the plant measurements. Therefore, the models proposed herein can assist in the pipe wall monitoring program for the nuclear power plant by way of concentrating the measuring point on the possible sites of severe E/C wear for the piping and reducing the measurement labor works

  10. Statistical downscaling of IPCC sea surface wind and wind energy predictions for U.S. east coastal ocean, Gulf of Mexico and Caribbean Sea

    Science.gov (United States)

    Yao, Zhigang; Xue, Zuo; He, Ruoying; Bao, Xianwen; Song, Jun

    2016-08-01

    A multivariate statistical downscaling method is developed to produce regional, high-resolution, coastal surface wind fields based on the IPCC global model predictions for the U.S. east coastal ocean, the Gulf of Mexico (GOM), and the Caribbean Sea. The statistical relationship is built upon linear regressions between the empirical orthogonal function (EOF) spaces of a cross- calibrated, multi-platform, multi-instrument ocean surface wind velocity dataset (predictand) and the global NCEP wind reanalysis (predictor) over a 10 year period from 2000 to 2009. The statistical relationship is validated before applications and its effectiveness is confirmed by the good agreement between downscaled wind fields based on the NCEP reanalysis and in-situ surface wind measured at 16 National Data Buoy Center (NDBC) buoys in the U.S. east coastal ocean and the GOM during 1992-1999. The predictand-predictor relationship is applied to IPCC GFDL model output (2.0°×2.5°) of downscaled coastal wind at 0.25°×0.25° resolution. The temporal and spatial variability of future predicted wind speeds and wind energy potential over the study region are further quantified. It is shown that wind speed and power would significantly be reduced in the high CO2 climate scenario offshore of the mid-Atlantic and northeast U.S., with the speed falling to one quarter of its original value.

  11. Comparison of four Adaboost algorithm based artificial neural networks in wind speed predictions

    International Nuclear Information System (INIS)

    Liu, Hui; Tian, Hong-qi; Li, Yan-fei; Zhang, Lei

    2015-01-01

    Highlights: • Four hybrid algorithms are proposed for the wind speed decomposition. • Adaboost algorithm is adopted to provide a hybrid training framework. • MLP neural networks are built to do the forecasting computation. • Four important network training algorithms are included in the MLP networks. • All the proposed hybrid algorithms are suitable for the wind speed predictions. - Abstract: The technology of wind speed prediction is important to guarantee the safety of wind power utilization. In this paper, four different hybrid methods are proposed for the high-precision multi-step wind speed predictions based on the Adaboost (Adaptive Boosting) algorithm and the MLP (Multilayer Perceptron) neural networks. In the hybrid Adaboost–MLP forecasting architecture, four important algorithms are adopted for the training and modeling of the MLP neural networks, including GD-ALR-BP algorithm, GDM-ALR-BP algorithm, CG-BP-FR algorithm and BFGS algorithm. The aim of the study is to investigate the promoted forecasting percentages of the MLP neural networks by the Adaboost algorithm’ optimization under various training algorithms. The hybrid models in the performance comparison include Adaboost–GD-ALR-BP–MLP, Adaboost–GDM-ALR-BP–MLP, Adaboost–CG-BP-FR–MLP, Adaboost–BFGS–MLP, GD-ALR-BP–MLP, GDM-ALR-BP–MLP, CG-BP-FR–MLP and BFGS–MLP. Two experimental results show that: (1) the proposed hybrid Adaboost–MLP forecasting architecture is effective for the wind speed predictions; (2) the Adaboost algorithm has promoted the forecasting performance of the MLP neural networks considerably; (3) among the proposed Adaboost–MLP forecasting models, the Adaboost–CG-BP-FR–MLP model has the best performance; and (4) the improved percentages of the MLP neural networks by the Adaboost algorithm decrease step by step with the following sequence of training algorithms as: GD-ALR-BP, GDM-ALR-BP, CG-BP-FR and BFGS

  12. Improved prediction of aerodynamic noise from wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Guidati, G.; Bareiss, R.; Wagner, S. [Univ. of Stuttgart, Inst. of Aerodynamics and Gasdynamics, Stuttgart (Germany)

    1997-12-31

    This paper focuses on an improved prediction model for inflow-turbulence noise which takes the true airfoil shape into account. Predictions are compared to the results of acoustic measurements on three 2D-models of 0.25 m chord. Two of the models have NACA-636xx airfoils of 12% and 18% relative thickness. The third airfoil was acoustically optimized by using the new prediction model. In the experiments the turbulence intensity of the flow was strongly increased by mounting a grid with 60 mm wide meshes and 12 mm thick rods onto the tunnel exhaust nozzle. The sound radiated from the airfoil was distinguished by the tunnel background noise by using an acoustic antenna consisting of a cross array of 36 microphones in total. An application of a standard beam-forming algorithm allows to determine how much noise is radiated from different parts of the models. This procedure normally results in a peak at the leading and trailing edge of the airfoil. The strength of the leading-edge peak is taken as the source strength for inflow-turbulence noise. (LN) 14 refs.

  13. Prediction and analysis of infra and low-frequency noise of upwind horizontal axis wind turbine using statistical wind speed model

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Gwang-Se; Cheong, Cheolung, E-mail: ccheong@pusan.ac.kr [School of Mechanical Engineering, Pusan National University, Busan, 609-745, Rep. of Korea (Korea, Republic of)

    2014-12-15

    Despite increasing concern about low-frequency noise of modern large horizontal-axis wind turbines (HAWTs), few studies have focused on its origin or its prediction methods. In this paper, infra- and low-frequency (the ILF) wind turbine noise are closely examined and an efficient method is developed for its prediction. Although most previous studies have assumed that the ILF noise consists primarily of blade passing frequency (BPF) noise components, these tonal noise components are seldom identified in the measured noise spectrum, except for the case of downwind wind turbines. In reality, since modern HAWTs are very large, during rotation, a single blade of the turbine experiences inflow with variation in wind speed in time as well as in space, breaking periodic perturbations of the BPF. Consequently, this transforms acoustic contributions at the BPF harmonics into broadband noise components. In this study, the ILF noise of wind turbines is predicted by combining Lowson’s acoustic analogy with the stochastic wind model, which is employed to reproduce realistic wind speed conditions. In order to predict the effects of these wind conditions on pressure variation on the blade surface, unsteadiness in the incident wind speed is incorporated into the XFOIL code by varying incident flow velocities on each blade section, which depend on the azimuthal locations of the rotating blade. The calculated surface pressure distribution is subsequently used to predict acoustic pressure at an observing location by using Lowson’s analogy. These predictions are compared with measured data, which ensures that the present method can reproduce the broadband characteristics of the measured low-frequency noise spectrum. Further investigations are carried out to characterize the IFL noise in terms of pressure loading on blade surface, narrow-band noise spectrum and noise maps around the turbine.

  14. Prediction and analysis of infra and low-frequency noise of upwind horizontal axis wind turbine using statistical wind speed model

    Directory of Open Access Journals (Sweden)

    Gwang-Se Lee

    2014-12-01

    Full Text Available Despite increasing concern about low-frequency noise of modern large horizontal-axis wind turbines (HAWTs, few studies have focused on its origin or its prediction methods. In this paper, infra- and low-frequency (the ILF wind turbine noise are closely examined and an efficient method is developed for its prediction. Although most previous studies have assumed that the ILF noise consists primarily of blade passing frequency (BPF noise components, these tonal noise components are seldom identified in the measured noise spectrum, except for the case of downwind wind turbines. In reality, since modern HAWTs are very large, during rotation, a single blade of the turbine experiences inflow with variation in wind speed in time as well as in space, breaking periodic perturbations of the BPF. Consequently, this transforms acoustic contributions at the BPF harmonics into broadband noise components. In this study, the ILF noise of wind turbines is predicted by combining Lowson’s acoustic analogy with the stochastic wind model, which is employed to reproduce realistic wind speed conditions. In order to predict the effects of these wind conditions on pressure variation on the blade surface, unsteadiness in the incident wind speed is incorporated into the XFOIL code by varying incident flow velocities on each blade section, which depend on the azimuthal locations of the rotating blade. The calculated surface pressure distribution is subsequently used to predict acoustic pressure at an observing location by using Lowson’s analogy. These predictions are compared with measured data, which ensures that the present method can reproduce the broadband characteristics of the measured low-frequency noise spectrum. Further investigations are carried out to characterize the IFL noise in terms of pressure loading on blade surface, narrow-band noise spectrum and noise maps around the turbine.

  15. [Anti-erosion effect of hedgerows in hillside croplands of Danjiangkou based on the evaluation with water erosion prediction project (WEPP) model].

    Science.gov (United States)

    Xiong, Qin-xue; Liu, Zhang-yong; Yao, Gui-zhi; Li, Ben-zhou

    2010-09-01

    Based on the data of field experiments on the hillside croplands of Danjiangkou, Hubei Province of China, the input files of crop characters, management measures, slope gradient and length, and soil properties for running WEPP model (Hillslope version) were established. Combining with the local weather data, a simulation study with the model was made on the runoff and soil loss of the croplands protected by four kinds of hedgerows (Amorpha fruticosa, Lonicera japonica, Hemerocallis fulva, and Poa sphondylodes) in Danjiangkou area. The resulted showed that WEPP model could accurately simulate the anti-erosion effect of hedgerows in hillside farmlands in the study area. Using this model not only reduced test number, but also saved time and effort, being able to provide scientific basis for the popularization and application of hedgerows. Among the four hedgerows, Amorpha fruticosa had the best anti-erosion effect. According to the simulation, the optimal planting density of A. fruticosa hedgerows in the farmlands was 1 m x 15 m at slope gradient 5 degrees, 1 m x 10 m at slope gradient 15 degrees, and 1 m x 3 m at slope gradient 25 degrees.

  16. Towards accurate performance prediction of a vertical axis wind turbine operating at different tip speed ratios

    NARCIS (Netherlands)

    Rezaeiha, A.; Kalkman, I.; Blocken, B.J.E.

    2017-01-01

    Accurate prediction of the performance of a vertical-axis wind turbine (VAWT) using CFD simulation requires the employment of a sufficiently fine azimuthal increment (dθ) combined with a mesh size at which essential flow characteristics can be accurately resolved. Furthermore, the domain size needs

  17. Development of ANN Model for Wind Speed Prediction as a Support for Early Warning System

    Directory of Open Access Journals (Sweden)

    Ivan Marović

    2017-01-01

    Full Text Available The impact of natural disasters increases every year with more casualties and damage to property and the environment. Therefore, it is important to prevent consequences by implementation of the early warning system (EWS in order to announce the possibility of the harmful phenomena occurrence. In this paper, focus is placed on the implementation of the EWS on the micro location in order to announce possible harmful phenomena occurrence caused by wind. In order to predict such phenomena (wind speed, an artificial neural network (ANN prediction model is developed. The model is developed on the basis of the input data obtained by local meteorological station on the University of Rijeka campus area in the Republic of Croatia. The prediction model is validated and evaluated by visual and common calculation approaches, after which it was found that it is possible to perform very good wind speed prediction for time steps Δt=1 h, Δt=3 h, and Δt=8 h. The developed model is implemented in the EWS as a decision support for improvement of the existing “procedure plan in a case of the emergency caused by stormy wind or hurricane, snow and occurrence of the ice on the University of Rijeka campus.”

  18. Health-aware Model Predictive Control of Wind Turbines using Fatigue Prognosis

    DEFF Research Database (Denmark)

    Sardi, Hector Eloy Sanchez; Escobet, Teressa; Puig, Vicenc

    2015-01-01

    management module with the control provides a mechanism for the wind turbine to operate safely and optimize the trade-off between components life and energy production. The research presented in this paper explores the integration of model predictive control (MPC) with fatigue-based prognosis approach...

  19. Model Predictive Control of Trailing Edge Flaps on a wind turbine blade

    DEFF Research Database (Denmark)

    Castaignet, Damien; Poulsen, Niels Kjølstad; Buhl, Thomas

    2011-01-01

    Trailing Edge Flaps on wind turbine blades have been studied in order to achieve fatigue load reduction on the turbine components. We show in this paper how Model Predictive Control can be used to do frequency weighted control of the trailing edge flaps in order to reduce fatigue damage on the bl...

  20. Fatigue life prediction and strength degradation of wind turbine rotor blade composites

    NARCIS (Netherlands)

    Nijssen, R.P.L.

    2006-01-01

    Wind turbine rotor blades are subjected to a large number of highly variable loads, but life predictions are typically based on constant amplitude fatigue behaviour. Therefore, it is important to determine how service life under variable amplitude fatigue can be estimated from constant amplitude

  1. A LIDAR-assisted model predictive controller added on a traditional wind turbine controller

    DEFF Research Database (Denmark)

    Mirzaei, Mahmood; Hansen, Morten Hartvig

    2016-01-01

    control and opens the market of retrofitting existing wind turbines with the new technology. In this paper, we suggest a model predictive controller (MPC) that is added to the basic gain scheduled PI controller of a WT to enhance the performance of the closed loop system using LIDAR measurements...

  2. Incorporating Wind Power Forecast Uncertainties Into Stochastic Unit Commitment Using Neural Network-Based Prediction Intervals.

    Science.gov (United States)

    Quan, Hao; Srinivasan, Dipti; Khosravi, Abbas

    2015-09-01

    Penetration of renewable energy resources, such as wind and solar power, into power systems significantly increases the uncertainties on system operation, stability, and reliability in smart grids. In this paper, the nonparametric neural network-based prediction intervals (PIs) are implemented for forecast uncertainty quantification. Instead of a single level PI, wind power forecast uncertainties are represented in a list of PIs. These PIs are then decomposed into quantiles of wind power. A new scenario generation method is proposed to handle wind power forecast uncertainties. For each hour, an empirical cumulative distribution function (ECDF) is fitted to these quantile points. The Monte Carlo simulation method is used to generate scenarios from the ECDF. Then the wind power scenarios are incorporated into a stochastic security-constrained unit commitment (SCUC) model. The heuristic genetic algorithm is utilized to solve the stochastic SCUC problem. Five deterministic and four stochastic case studies incorporated with interval forecasts of wind power are implemented. The results of these cases are presented and discussed together. Generation costs, and the scheduled and real-time economic dispatch reserves of different unit commitment strategies are compared. The experimental results show that the stochastic model is more robust than deterministic ones and, thus, decreases the risk in system operations of smart grids.

  3. Dynamic Loads and Wake Prediction for Large Wind Turbines Based on Free Wake Method

    Institute of Scientific and Technical Information of China (English)

    Cao Jiufa; Wang Tongguang; Long Hui; Ke Shitang; Xu Bofeng

    2015-01-01

    With large scale wind turbines ,the issue of aerodynamic elastic response is even more significant on dy-namic behaviour of the system .Unsteady free vortex wake method is proposed to calculate the shape of wake and aerodynamic load .Considering the effect of aerodynamic load ,inertial load and gravity load ,the decoupling dy-namic equations are established by using finite element method in conjunction of the modal method and equations are solved numerically by Newmark approach .Finally ,the numerical simulation of a large scale wind turbine is performed through coupling the free vortex wake modelling with structural modelling .The results show that this coupling model can predict the flexible wind turbine dynamic characteristics effectively and efficiently .Under the influence of the gravitational force ,the dynamic response of flapwise direction contributes to the dynamic behavior of edgewise direction under the operational condition of steady wind speed .The difference in dynamic response be-tween the flexible and rigid wind turbines manifests when the aerodynamics/structure coupling effect is of signifi-cance in both wind turbine design and performance calculation .

  4. Observations and Predictability of Gap Winds in the Salmon River Canyon of Central Idaho, USA

    Directory of Open Access Journals (Sweden)

    Natalie S. Wagenbrenner

    2018-01-01

    Full Text Available This work investigates gap winds in a steep, deep river canyon prone to wildland fire. The driving mechanisms and the potential for forecasting the gap winds are investigated. The onset and strength of the gap winds are found to be correlated to the formation of an along-gap pressure gradient linked to periodic development of a thermal trough in the Pacific Northwest, USA. Numerical simulations are performed using a reanalysis dataset to investigate the ability of numerical weather prediction (NWP to simulate the observed gap wind events, including the timing and flow characteristics within the canyon. The effects of model horizontal grid spacing and terrain representation are considered. The reanalysis simulations suggest that horizontal grid spacings used in operational NWP could be sufficient for simulating the gap flow events given the regional-scale depression in which the Salmon River Canyon is situated. The strength of the events, however, is under-predicted due, at least in part, to terrain smoothing in the model. Routine NWP, however, is found to have mixed results in terms of forecasting the gap wind events, primarily due to problems in simulating the regional sea level pressure system correctly.

  5. Predicting geomagnetic storms from solar-wind data using time-delay neural networks

    Directory of Open Access Journals (Sweden)

    H. Gleisner

    1996-07-01

    Full Text Available We have used time-delay feed-forward neural networks to compute the geomagnetic-activity index Dst one hour ahead from a temporal sequence of solar-wind data. The input data include solar-wind density n, velocity V and the southward component Bz of the interplanetary magnetic field. Dst is not included in the input data. The networks implement an explicit functional relationship between the solar wind and the geomagnetic disturbance, including both direct and time-delayed non-linear relations. In this study we especially consider the influence of varying the temporal size of the input-data sequence. The networks are trained on data covering 6600 h, and tested on data covering 2100 h. It is found that the initial and main phases of geomagnetic storms are well predicted, almost independent of the length of the input-data sequence. However, to predict the recovery phase, we have to use up to 20 h of solar-wind input data. The recovery phase is mainly governed by the ring-current loss processes, and is very much dependent on the ring-current history, and thus also the solar-wind history. With due consideration of the time history when optimizing the networks, we can reproduce 84% of the Dst variance.

  6. Modeling soil erosion in a watershed

    OpenAIRE

    Lanuza, R.

    1999-01-01

    Most erosion models have been developed based on a plot scale and have limited application to a watershed due to the differences in aerial scale. In order to address this limitation, a GIS-assisted methodology for modeling soil erosion was developed using PCRaster to predict the rate of soil erosion at watershed level; identify the location of erosion prone areas; and analyze the impact of landuse changes on soil erosion. The general methodology of desktop modeling or soil erosion at watershe...

  7. Correaltion of full-scale drag predictions with flight measurements on the C-141A aircraft. Phase 2: Wind tunnel test, analysis, and prediction techniques. Volume 1: Drag predictions, wind tunnel data analysis and correlation

    Science.gov (United States)

    Macwilkinson, D. G.; Blackerby, W. T.; Paterson, J. H.

    1974-01-01

    The degree of cruise drag correlation on the C-141A aircraft is determined between predictions based on wind tunnel test data, and flight test results. An analysis of wind tunnel tests on a 0.0275 scale model at Reynolds number up to 3.05 x 1 million/MAC is reported. Model support interference corrections are evaluated through a series of tests, and fully corrected model data are analyzed to provide details on model component interference factors. It is shown that predicted minimum profile drag for the complete configuration agrees within 0.75% of flight test data, using a wind tunnel extrapolation method based on flat plate skin friction and component shape factors. An alternative method of extrapolation, based on computed profile drag from a subsonic viscous theory, results in a prediction four percent lower than flight test data.

  8. Prediction of soil stability and erosion in semiarid regions using numerical hydrological model (MCAT) and airborne hyperspectral imagery

    Science.gov (United States)

    Brook, Anna; Wittenberg, Lea

    2015-04-01

    promising models is the MCAT, which is a MATLAB library of visual and numerical analysis tools for the evaluation of hydrological and environmental models. The model applied in this paper presents an innovative infrastructural system for predicting soil stability and erosion impacts. This integrated model is applicable to mixed areas with spatially varying soil properties, landscape, and land-cover characteristics. Data from a semiarid site in southern Israel was used to evaluate the model and analyze fundamental erosion mechanisms. The findings estimate the sensitivity of the suggested model to the physical parameters and encourage the use of hyperspectral remote sensing imagery (HSI). The proposed model is integrated according to the following stages: 1. The soil texture, aggregation, soil moisture estimated via airborne HSI data, including soil surface clay and calcium carbonate erosions; 2. The mechanical stability of soil assessed via pedo-transfer function corresponding to load dependent changes in soil physical properties due to pre-compression stress (set of equations study shear strength parameters take into account soil texture, aggregation, soil moisture and ecological soil variables); 3. The precipitation-related runoff model program (RMP) satisfactorily reproduces the observed seasonal mean and variation of surface runoff for the current climate simulation; 4. The Monte Carlo Analysis Toolbox (MCAT), a library of visual and numerical analysis tools for the evaluation of hydrological and environmental models, is proposed as a tool for integrate all the approaches to an applicable model. The presented model overcomes the limitations of existing modeling methods by integrating physical data produced via HSI and yet stays generic in terms of space and time independency.

  9. A comparative study of various inflow boundary conditions and turbulence models for wind turbine wake predictions

    Science.gov (United States)

    Tian, Lin-Lin; Zhao, Ning; Song, Yi-Lei; Zhu, Chun-Ling

    2018-05-01

    This work is devoted to perform systematic sensitivity analysis of different turbulence models and various inflow boundary conditions in predicting the wake flow behind a horizontal axis wind turbine represented by an actuator disc (AD). The tested turbulence models are the standard k-𝜀 model and the Reynolds Stress Model (RSM). A single wind turbine immersed in both uniform flows and in modeled atmospheric boundary layer (ABL) flows is studied. Simulation results are validated against the field experimental data in terms of wake velocity and turbulence intensity.

  10. Bayesian based Prognostic Model for Predictive Maintenance of Offshore Wind Farms

    DEFF Research Database (Denmark)

    Asgarpour, Masoud

    2017-01-01

    monitoring, fault detection and predictive maintenance of offshore wind components is defined. The diagnostic model defined in this paper is based on degradation, remaining useful lifetime and hybrid inspection threshold models. The defined degradation model is based on an exponential distribution......The operation and maintenance costs of offshore wind farms can be significantly reduced if existing corrective actions are performed as efficient as possible and if future corrective actions are avoided by performing sufficient preventive actions. In this paper a prognostic model for degradation...

  11. A Gaussian mixture copula model based localized Gaussian process regression approach for long-term wind speed prediction

    International Nuclear Information System (INIS)

    Yu, Jie; Chen, Kuilin; Mori, Junichi; Rashid, Mudassir M.

    2013-01-01

    Optimizing wind power generation and controlling the operation of wind turbines to efficiently harness the renewable wind energy is a challenging task due to the intermittency and unpredictable nature of wind speed, which has significant influence on wind power production. A new approach for long-term wind speed forecasting is developed in this study by integrating GMCM (Gaussian mixture copula model) and localized GPR (Gaussian process regression). The time series of wind speed is first classified into multiple non-Gaussian components through the Gaussian mixture copula model and then Bayesian inference strategy is employed to incorporate the various non-Gaussian components using the posterior probabilities. Further, the localized Gaussian process regression models corresponding to different non-Gaussian components are built to characterize the stochastic uncertainty and non-stationary seasonality of the wind speed data. The various localized GPR models are integrated through the posterior probabilities as the weightings so that a global predictive model is developed for the prediction of wind speed. The proposed GMCM–GPR approach is demonstrated using wind speed data from various wind farm locations and compared against the GMCM-based ARIMA (auto-regressive integrated moving average) and SVR (support vector regression) methods. In contrast to GMCM–ARIMA and GMCM–SVR methods, the proposed GMCM–GPR model is able to well characterize the multi-seasonality and uncertainty of wind speed series for accurate long-term prediction. - Highlights: • A novel predictive modeling method is proposed for long-term wind speed forecasting. • Gaussian mixture copula model is estimated to characterize the multi-seasonality. • Localized Gaussian process regression models can deal with the random uncertainty. • Multiple GPR models are integrated through Bayesian inference strategy. • The proposed approach shows higher prediction accuracy and reliability

  12. Short-term wind speed prediction using an unscented Kalman filter based state-space support vector regression approach

    International Nuclear Information System (INIS)

    Chen, Kuilin; Yu, Jie

    2014-01-01

    Highlights: • A novel hybrid modeling method is proposed for short-term wind speed forecasting. • Support vector regression model is constructed to formulate nonlinear state-space framework. • Unscented Kalman filter is adopted to recursively update states under random uncertainty. • The new SVR–UKF approach is compared to several conventional methods for short-term wind speed prediction. • The proposed method demonstrates higher prediction accuracy and reliability. - Abstract: Accurate wind speed forecasting is becoming increasingly important to improve and optimize renewable wind power generation. Particularly, reliable short-term wind speed prediction can enable model predictive control of wind turbines and real-time optimization of wind farm operation. However, this task remains challenging due to the strong stochastic nature and dynamic uncertainty of wind speed. In this study, unscented Kalman filter (UKF) is integrated with support vector regression (SVR) based state-space model in order to precisely update the short-term estimation of wind speed sequence. In the proposed SVR–UKF approach, support vector regression is first employed to formulate a nonlinear state-space model and then unscented Kalman filter is adopted to perform dynamic state estimation recursively on wind sequence with stochastic uncertainty. The novel SVR–UKF method is compared with artificial neural networks (ANNs), SVR, autoregressive (AR) and autoregressive integrated with Kalman filter (AR-Kalman) approaches for predicting short-term wind speed sequences collected from three sites in Massachusetts, USA. The forecasting results indicate that the proposed method has much better performance in both one-step-ahead and multi-step-ahead wind speed predictions than the other approaches across all the locations

  13. Measuring Dust Emission from the Mojave Desert (USA) by Daily Remote-Camera Observations and Wind-Erosion Measurements: Bearing on "Unseen" Sources and Global Dust Abundance

    Science.gov (United States)

    Reynolds, R. L.; Urban, F.; Goldstein, H. L.; Fulton, R.

    2017-12-01

    A large gap in understanding the effects of atmospheric dust at all spatial scales is uncertainty about how much and whence dust is emitted annually. Digital recording of dust emission at high spatial and temporal resolution would, together with periodic flux measurements, support improved estimates of local-scale dust flux where infrastructure could support remote internet enabled cameras. Such recording would also elucidate wind-erosion dynamics when combined with meteorological data. Remote camera recording of dust-emitting settings on and around Soda Lake (Mojave Desert) was conducted every 15 minutes during daylight between 10 Nov. 2010 and 31 Dec. 2016 and images uploaded to a web server. Examination of 135,000 images revealed frequent dust events, termed "dust days" when plumes obscured mountains beyond source areas. Such days averaged 68 (sd=10) per year (2011 through 2016). We examined satellite retrievals (MODIS, GOES) for dust events during six cloudless days of highest and longest duration dust emission but none were observed. From Apr. 2000 through May 2013, aeolian sediments collected at three sites were sampled and weighed. Estimates of the emitted mass of silt- and clay-size fractions were made on the basis of measured horizontal mass flux, particle sizes of sediment in collectors, and roughly determined areas of dust generation. Over this period, nearly 4 Tg yr-1 of dust (as particulate matter flood in the basin in late Dec. 2010 that deposited flood sediment across the lake basin. Increased emission was likely related to the availability of fresh, unanchored flood sediment. Within the Mojave and Great Basin deserts of North America, many settings akin to those at Soda Lake similarly emit dust that is rarely detected in satellite retrievals. These findings strongly imply that local and regional dust emissions from western North America are far underestimated and that, by extension to relatively small dust-source areas across all drylands, global

  14. Vibration Analysis and Time Series Prediction for Wind Turbine Gearbox Prognostics

    Directory of Open Access Journals (Sweden)

    Hossam A. Gabbar

    2013-01-01

    Full Text Available Premature failure of a gearbox in a wind turbine poses a high risk of increasing the operational and maintenance costs and decreasing the profit margins. Prognostics and health management (PHM techniques are widely used to access the current health condition of the gearbox and project it in future to predict premature failures. This paper proposes such techniques for predicting gearbox health condition index extracted from the vibration signals emanating from the gearbox. The progression of the monitoring index is predicted using two different prediction techniques, adaptive neuro-fuzzy inference system (ANFIS and nonlinear autoregressive model with exogenous inputs (NARX. The proposed prediction techniques are evaluated through sun-spot data-set and applied on vibration based health related monitoring index calculated through psychoacoustic phenomenon. A comparison is given for their prediction accuracy. The results are helpful in understanding the relationship of machine conditions, the corresponding indicating features, the level of damage/degradation, and their progression.

  15. Using high-performance mathematical modelling tools to predict erosion and sediment fluxes in peri-urban catchments

    Science.gov (United States)

    Pereira, André; Conde, Daniel; Ferreira, Carla S. S.; Walsh, Rory; Ferreira, Rui M. L.

    2017-04-01

    Deforestation and urbanization generally lead to increased soil erosion andthrough the indirect effect of increased overland flow and peak flood discharges. Mathematical modelling tools can be helpful for predicting the spatial distribution of erosion and the morphological changes on the channel network. This is especially useful to predict the impacts of land-use changes in parts of the watershed, namely due to urbanization. However, given the size of the computational domain (normally the watershed itself), the need for high spatial resolution data to model accurately sediment transport processes and possible need to model transcritical flows, the computational cost is high and requires high-performance computing techniques. The aim of this work is to present the latest developments of the hydrodynamic and morphological model STAV2D and its applicability to predict runoff and erosion at watershed scale. STAV2D was developed at CEris - Instituto Superior Técnico, Universidade de Lisboa - as a tool particularly appropriated to model strong transient flows in complex and dynamic geometries. It is based on an explicit, first-order 2DH finite-volume discretization scheme for unstructured triangular meshes, in which a flux-splitting technique is paired with a reviewed Roe-Riemann solver, yielding a model applicable to discontinuous flows over time-evolving geometries. STAV2D features solid transport in both Euleran and Lagrangian forms, with the aim of describing the transport of fine natural sediments and then the large individual debris. The model has been validated with theoretical solutions and laboratory experiments (Canelas et al., 2013 & Conde et al., 2015). STAV-2D now supports fully distributed and heterogeneous simulations where multiple different hardware devices can be used to accelerate computation time within a unified Object-Oriented approach: the source code for CPU and GPU has the same compilation units and requires no device specific branches, like

  16. Effect of wind turbine mortality on noctule bats in Sweden: predictions from a simple population model

    Energy Technology Data Exchange (ETDEWEB)

    Rydell, Jens; Hedenstroem, Anders; Green, Martin

    2011-07-01

    Full text: The noctule bat Nyctalus noctula is apparently the species most seriously affected by wind turbine mortality in northern Europe. It occurs in south Sweden up to about 60oN, although the abundance is much higher in lowland agricultural areas than in forests. We used a recent estimate of 90 000 individuals as the population size in Sweden, and assumed a stable starting population not affected by mortality from wind turbines. In the absence of data from Sweden, we used demographic data and fatality rates at wind turbines (0.9 noctules/turbine/year) obtained in eastern Germany. Population development up to year 2020 was calculated, based on the current estimate of wind farm development in Sweden; ca. 1000 present and 2500 additional turbines within the area of noctule distribution. The results suggest that the additional mortality at wind turbines may affect the noctule bat in Sweden at the population level. However, the effect will probably be small, particularly in comparison with other anthropogenic sources. We are currently using the model to predict the effect on other bat species and birds. (Author)

  17. Comparison of Flight Measured, Predicted and Wind Tunnel Measured Winglet Characteristics on a KC-135 Aircraft

    Science.gov (United States)

    Dodson, R. O., Jr.

    1982-01-01

    One of the objectives of the KC-135 Winglet Flight Research and Demonstration Program was to obtain experimental flight test data to verify the theoretical and wind tunnel winglet aerodynamic performance prediction methods. Good agreement between analytic, wind tunnel and flight test performance was obtained when the known differences between the tests and analyses were accounted for. The flight test measured fuel mileage improvements for a 0.78 Mach number was 3.1 percent at 8 x 10(5) pounds W/delta and 5.5 percent at 1.05 x 10(6) pounds W/delta. Correcting the flight measured data for surface pressure differences between wind tunnel and flight resulted in a fuel mileage improvement of 4.4 percent at 8 x 10(5) pounds W/delta and 7.2 percent at 1.05 x 10(6) pounds W/delta. The performance improvement obtained was within the wind tunnel test data obtained from two different wind tunnel models. The buffet boundary data obtained for the baseline configuration was in good agreement with previous established data. Buffet data for the 15 deg cant/-4 deg incidence configuration showed a slight improvement, while the 15 deg cant/-2 deg incidence and 0 deg cant/-4 deg incidence data showed a slight deterioration.

  18. Energy Coordinative Optimization of Wind-Storage-Load Microgrids Based on Short-Term Prediction

    Directory of Open Access Journals (Sweden)

    Changbin Hu

    2015-02-01

    Full Text Available According to the topological structure of wind-storage-load complementation microgrids, this paper proposes a method for energy coordinative optimization which focuses on improvement of the economic benefits of microgrids in the prediction framework. First of all, the external characteristic mathematical model of distributed generation (DG units including wind turbines and storage batteries are established according to the requirements of the actual constraints. Meanwhile, using the minimum consumption costs from the external grid as the objective function, a grey prediction model with residual modification is introduced to output the predictive wind turbine power and load at specific periods. Second, based on the basic framework of receding horizon optimization, an intelligent genetic algorithm (GA is applied to figure out the optimum solution in the predictive horizon for the complex non-linear coordination control model of microgrids. The optimum results of the GA are compared with the receding solution of mixed integer linear programming (MILP. The obtained results show that the method is a viable approach for energy coordinative optimization of microgrid systems for energy flow and reasonable schedule. The effectiveness and feasibility of the proposed method is verified by examples.

  19. Predicting the effectiveness of different mulching techniques in reducing post-fire runoff and erosion at plot scale with the RUSLE, MMF and PESERA models.

    Science.gov (United States)

    Vieira, D C S; Serpa, D; Nunes, J P C; Prats, S A; Neves, R; Keizer, J J

    2018-08-01

    Wildfires have become a recurrent threat for many Mediterranean forest ecosystems. The characteristics of the Mediterranean climate, with its warm and dry summers and mild and wet winters, make this a region prone to wildfire occurrence as well as to post-fire soil erosion. This threat is expected to be aggravated in the future due to climate change and land management practices and planning. The wide recognition of wildfires as a driver for runoff and erosion in burnt forest areas has created a strong demand for model-based tools for predicting the post-fire hydrological and erosion response and, in particular, for predicting the effectiveness of post-fire management operations to mitigate these responses. In this study, the effectiveness of two post-fire treatments (hydromulch and natural pine needle mulch) in reducing post-fire runoff and soil erosion was evaluated against control conditions (i.e. untreated conditions), at different spatial scales. The main objective of this study was to use field data to evaluate the ability of different erosion models: (i) empirical (RUSLE), (ii) semi-empirical (MMF), and (iii) physically-based (PESERA), to predict the hydrological and erosive response as well as the effectiveness of different mulching techniques in fire-affected areas. The results of this study showed that all three models were reasonably able to reproduce the hydrological and erosive processes occurring in burned forest areas. In addition, it was demonstrated that the models can be calibrated at a small spatial scale (0.5 m 2 ) but provide accurate results at greater spatial scales (10 m 2 ). From this work, the RUSLE model seems to be ideal for fast and simple applications (i.e. prioritization of areas-at-risk) mainly due to its simplicity and reduced data requirements. On the other hand, the more complex MMF and PESERA models would be valuable as a base of a possible tool for assessing the risk of water contamination in fire-affected water bodies and

  20. Wind Speed Prediction Using a Univariate ARIMA Model and a Multivariate NARX Model

    Directory of Open Access Journals (Sweden)

    Erasmo Cadenas

    2016-02-01

    Full Text Available Two on step ahead wind speed forecasting models were compared. A univariate model was developed using a linear autoregressive integrated moving average (ARIMA. This method’s performance is well studied for a large number of prediction problems. The other is a multivariate model developed using a nonlinear autoregressive exogenous artificial neural network (NARX. This uses the variables: barometric pressure, air temperature, wind direction and solar radiation or relative humidity, as well as delayed wind speed. Both models were developed from two databases from two sites: an hourly average measurements database from La Mata, Oaxaca, Mexico, and a ten minute average measurements database from Metepec, Hidalgo, Mexico. The main objective was to compare the impact of the various meteorological variables on the performance of the multivariate model of wind speed prediction with respect to the high performance univariate linear model. The NARX model gave better results with improvements on the ARIMA model of between 5.5% and 10. 6% for the hourly database and of between 2.3% and 12.8% for the ten minute database for mean absolute error and mean squared error, respectively.

  1. Predicting the effectiveness of different mulching techniques to reduce post-fire runoff and erosion in Mediterranean pine stands - does cover matter?

    Science.gov (United States)

    Vieira, Diana; Nunes, João; Prats, Sergio; Serpa, Dalila; Keizer, Jan

    2016-04-01

    Wildfires have become a recurrent threat for many forest ecosystems of the Mediterranean. The characteristics of the Mediterranean climate with its warm and dry summers and mild and wet winters make it prone to wildfire occurrence as well as to post-fire soil erosion. Furthermore, climate change and continuation of current land management practices and planning are generally expected to further increase this threat. The wide recognition of the effects of wildfires to enhance runoff and erosion has created a strong demand for model-based tools for predicting the post-fire hydrological and erosion response and, in particular, for predicting the effectiveness of post-fire forestry operations to mitigate these responses. Such a tool should allow to identify areas with elevated risks of soil erosion and to evaluate which measures should be applied and when to minimize these risks. A key element in evaluating these measures is also their costs, in order to optimize the use of the limited resources that are typically available for post-fire land management. In this study, two "treatments" are compared with control conditions (i.e. doing nothing) after a wildfire with a moderate soil burn severity: (i) 4 erosion plots were treated with hydro-mulch, (ii) 4 erosion plots were untreated but had a high pine needle cover quickly after the fire, due to needle cast from scorched pine crowns (often referred to as "natural mulching") (iii) 4 plots were untreated and had a very reduced protective litter cover . The main objective of this study was to asses if the revised MMF model could effectively predict the impacts of hydro-mulching and natural mulching with pine needle on runoff generation and the associated soil losses. If MMF could predict well the impact of natural mulching, it could be very useful in limiting the areas that should be considered for specific soil mitigation measures, especially in the case of wildfires that affect large areas with moderate severity. The

  2. Feature selection in wind speed prediction systems based on a hybrid coral reefs optimization – Extreme learning machine approach

    International Nuclear Information System (INIS)

    Salcedo-Sanz, S.; Pastor-Sánchez, A.; Prieto, L.; Blanco-Aguilera, A.; García-Herrera, R.

    2014-01-01

    Highlights: • A novel approach for short-term wind speed prediction is presented. • The system is formed by a coral reefs optimization algorithm and an extreme learning machine. • Feature selection is carried out with the CRO to improve the ELM performance. • The method is tested in real wind farm data in USA, for the period 2007–2008. - Abstract: This paper presents a novel approach for short-term wind speed prediction based on a Coral Reefs Optimization algorithm (CRO) and an Extreme Learning Machine (ELM), using meteorological predictive variables from a physical model (the Weather Research and Forecast model, WRF). The approach is based on a Feature Selection Problem (FSP) carried out with the CRO, that must obtain a reduced number of predictive variables out of the total available from the WRF. This set of features will be the input of an ELM, that finally provides the wind speed prediction. The CRO is a novel bio-inspired approach, based on the simulation of reef formation and coral reproduction, able to obtain excellent results in optimization problems. On the other hand, the ELM is a new paradigm in neural networks’ training, that provides a robust and extremely fast training of the network. Together, these algorithms are able to successfully solve this problem of feature selection in short-term wind speed prediction. Experiments in a real wind farm in the USA show the excellent performance of the CRO–ELM approach in this FSP wind speed prediction problem

  3. A simple method to downscale daily wind statistics to hourly wind data

    OpenAIRE

    Guo, Zhongling

    2013-01-01

    Wind is the principal driver in the wind erosion models. The hourly wind speed data were generally required for precisely wind erosion modeling. In this study, a simple method to generate hourly wind speed data from daily wind statistics (daily average and maximum wind speeds together or daily average wind speed only) was established. A typical windy location with 3285 days (9 years) measured hourly wind speed data were used to validate the downscaling method. The results showed that the over...

  4. Observations and predictions of wave runup, extreme water levels, and medium-term dune erosion during storm conditions

    OpenAIRE

    Suanez , Serge ,; Cancouët , Romain; Floc'h , France; Blaise , Emmanuel; Ardhuin , Fabrice; Filipot , Jean-François; Cariolet , Jean-Marie; Delacourt , Christophe

    2015-01-01

    Monitoring of dune erosion and accretion on the high-energy macrotidal Vougot beach in North Brittany (France) over the past decade (2004–2014) has revealed significant morphological changes. Dune toe erosion/accretion records have been compared with extreme water level measurements, defined as the sum of (i) astronomic tide; (ii) storm surge; and (iii) vertical wave runup. Runup parameterization was conducted using swash limits, beach profiles, and hydrodynamic (Hm0, Tm0,–1, and high tide wa...

  5. Practical use of offsite atmospheric measurements to enhance profitability of onsite wind prediction

    Energy Technology Data Exchange (ETDEWEB)

    Collier, Craig [GL Garrad Hassan (Canada)

    2011-07-01

    This paper presents the use of offsite atmospheric measurements to improve the profitability of onsite wind prediction. There are two common sensitivities used, intraday and interday. Results from US mid-western sites show that the error associated with wind predictions is large but there are possibilities for improvement. Inter- and intraday can be used traditionally to contribute towards NWP bias correction. Intraday alone can be used with machine learning and NWP. These techniques are compared and given in order of ease of use and potential accuracy gains. Some considerations and differences for all three techniques, namely, traditional, data assimilation and machine learning are also detailed. An offsite selection matrix shows how elements like location, geography and telemetry rate in the 3 techniques. The experimental setup for all 3 techniques over a 3-month period is given and the results are presented. It can be concluded that the results from these simple experiments show promise but vary in method and time scale.

  6. Application of model predictive control for optimal operation of wind turbines

    Science.gov (United States)

    Yuan, Yuan; Cao, Pei; Tang, J.

    2017-04-01

    For large-scale wind turbines, reducing maintenance cost is a major challenge. Model predictive control (MPC) is a promising approach to deal with multiple conflicting objectives using the weighed sum approach. In this research, model predictive control method is applied to wind turbine to find an optimal balance between multiple objectives, such as the energy capture, loads on turbine components, and the pitch actuator usage. The actuator constraints are integrated into the objective function at the control design stage. The analysis is carried out in both the partial load region and full load region, and the performances are compared with those of a baseline gain scheduling PID controller. The application of this strategy achieves enhanced balance of component loads, the average power and actuator usages in partial load region.

  7. Prediction of windings temperature rise in induction motors supplied with distorted voltage

    Energy Technology Data Exchange (ETDEWEB)

    Gnacinski, P. [Gdynia Maritime University, Department of Ship Electrical Power Engineering, Morska Street 83, 81-225 Gdynia (Poland)

    2008-04-15

    One of the features of ship power systems is a different level and intensity of disturbances appearing during routine operation - the rms voltage value and frequency deviation, voltage unbalance and waveform voltage distortion. As a result, marine induction machines are exposed to overheating due to the lowered voltage quality. This paper is devoted to windings temperature rise prediction in marine induction cage machines supplied with distorted voltage, which means real voltage conditions. The proposed method of prediction does not require detailed knowledge of the thermal properties of a machine. Although the method was developed for marine induction motors, it is applicable for industry machines supplied with distorted voltage. It can also be generalized and used for estimation of the steady state windings temperature rise of any electrical machinery in various work conditions. (author)

  8. Prediction of windings temperature rise in induction motors supplied with distorted voltage

    International Nuclear Information System (INIS)

    Gnacinski, P.

    2008-01-01

    One of the features of ship power systems is a different level and intensity of disturbances appearing during routine operation - the rms voltage value and frequency deviation, voltage unbalance and waveform voltage distortion. As a result, marine induction machines are exposed to overheating due to the lowered voltage quality. This paper is devoted to windings temperature rise prediction in marine induction cage machines supplied with distorted voltage, which means real voltage conditions. The proposed method of prediction does not require detailed knowledge of the thermal properties of a machine. Although the method was developed for marine induction motors, it is applicable for industry machines supplied with distorted voltage. It can also be generalized and used for estimation of the steady state windings temperature rise of any electrical machinery in various work conditions

  9. Model predictive control of trailing edge flaps on a wind turbine blade

    Energy Technology Data Exchange (ETDEWEB)

    Castaignet, D.B.

    2011-11-15

    Trailing edge flaps on wind turbine blades have been investigated for several years. Aero-servoelastic simulations carried out with different simulation tools, trailing edge flaps configurations and controller designs proved that trailing edge flaps are a suitable solution for reducing some of the wind turbine fatigue and extreme loads. This potential was confirmed with wind tunnel tests made on blade sections with trailing edge flaps and on a scaled two-bladed wind turbine in a wind tunnel. The work presented in this thesis includes a full-scale test run on a Vestas V27 wind turbine equipped with three trailing edge flaps on one blade, located on DTU's Risoe Campus in Roskilde, Denmark. This thesis is divided into three parts: the controller design, results from simulations, and results from the experiments. The trailing edge flaps controller designed for this project is based on a frequency-weighted model predictive control, tuned in order to target only the flapwise blade root loads at the frequencies contributing the most to blade root fatigue damage (the 1P, 2P and 3P frequencies), and to avoid unnecessary wear and tear of the actuators at high frequencies. A disturbance model consisting in periodic disturbances at the rotor speed harmonic frequencies and a quasi-steady input disturbance is aggregated to an analytical model of a spinning blade with trailing edge flaps. Simulations on a multi-megawatt wind turbine show the potential of the trailing edge flaps to reduce the flapwise blade root fatigue loads by 23%, but also the main shaft and the tower fatigue loads by up to 32%. Extreme loads during normal production also benefit from the trailing edge flaps. At last, the same controller was run on the Vestas V27 wind turbine located at the Risoe Campus of the Technical University of Denmark, in Roskilde, Denmark. One blade of the turbine was equipped with three independent trailing edge flaps. In spite of the failure of several sensors and actuators, the

  10. Active Power Optimal Control of Wind Turbines with Doubly Fed Inductive Generators Based on Model Predictive Control

    Directory of Open Access Journals (Sweden)

    Guo Jiuwang

    2015-01-01

    Full Text Available Because of the randomness and fluctuation of wind energy, as well as the impact of strongly nonlinear characteristic of variable speed constant frequency (VSCF wind power generation system with doubly fed induction generators (DFIG, traditional active power control strategies are difficult to achieve high precision control and the output power of wind turbines is more fluctuated. In order to improve the quality of output electric energy of doubly fed wind turbines, on the basis of analyzing the operating principles and dynamic characteristics of doubly fed wind turbines, this paper proposes a new active power optimal control method of doubly fed wind turbines based on predictive control theory. This method uses state space model of wind turbines, based on the prediction of the future state of wind turbines, moves horizon optimization, and meanwhile, gets the control signals of pitch angle and generator torque. Simulation results show that the proposed control strategies can guarantee the utilization efficiency for wind energy. Simultaneously, they can improve operation stability of wind turbines and the quality of electric energy.

  11. A review on the young history of the wind power short-term prediction

    DEFF Research Database (Denmark)

    Costa, A.; Crespo, A.; Navarro, J.

    2008-01-01

    This paper makes a brief review on 30 years of history of the wind power short-term prediction, since the first ideas and sketches on the theme to the actual state of the art oil models and tools, giving emphasis to the most significant proposals and developments. The two principal lines of thought...... on short-term prediction (mathematical and physical) are indistinctly treated here and comparisons between models and tools are avoided, mainly because, on the one hand, a standard for a measure of performance is still not adopted and, on the other hand, it is very important that the data are exactly...

  12. Predicting the impact of logging activities on soil erosion and water quality in steep, forested tropical islands

    Science.gov (United States)

    Wenger, Amelia S.; Atkinson, Scott; Santini, Talitha; Falinski, Kim; Hutley, Nicholas; Albert, Simon; Horning, Ned; Watson, James E. M.; Mumby, Peter J.; Jupiter, Stacy D.

    2018-04-01

    Increasing development in tropical regions provides new economic opportunities that can improve livelihoods, but it threatens the functional integrity and ecosystem services provided by terrestrial and aquatic ecosystems when conducted unsustainably. Given the small size of many islands, communities may have limited opportunities to replace loss and damage to the natural resources upon which they depend for ecosystem service provisioning, thus heightening the need for proactive, integrated management. This study quantifies the effectiveness of management strategies, stipulated in logging codes-of-practice, at minimizing soil erosion and sediment runoff as clearing extent increases, using Kolombangara Island, Solomon Islands as a case study. Further, we examine the ability of erosion reduction strategies to maintain sustainable soil erosion rates and reduce potential downstream impacts to drinking water and environmental water quality. We found that increasing land clearing—even with best management strategies in place—led to unsustainable levels of soil erosion and significant impacts to downstream water quality, compromising the integrity of the land for future agricultural uses, consistent access to clean drinking water, and important downstream ecosystems. Our results demonstrate that in order to facilitate sustainable development, logging codes of practice must explicitly link their soil erosion reduction strategies to soil erosion and downstream water quality thresholds, otherwise they will be ineffective at minimizing the impacts of logging activities. The approach taken here to explicitly examine soil erosion rates and downstream water quality in relation to best management practices and increasing land clearing should be applied more broadly across a range of ecosystems to inform decision-making about the socioeconomic and environmental trade-offs associated with logging, and other types of land use change.

  13. Predicting hurricane wind damage by claim payout based on Hurricane Ike in Texas

    Directory of Open Access Journals (Sweden)

    Ji-Myong Kim

    2016-09-01

    Full Text Available The increasing occurrence of natural disasters and their related damage have led to a growing demand for models that predict financial loss. Although considerable research on the financial losses related to natural disasters has found significant predictors, there has been a lack of comprehensive study that addresses the relationship among vulnerabilities, natural disasters, and the economic losses of individual buildings. This study identifies the vulnerability indicators for hurricanes to establish a metric to predict the related financial loss. We classify hurricane-prone areas by highlighting the spatial distribution of losses and vulnerabilities. This study used a Geographical Information System (GIS to combine and produce spatial data and a multiple regression method to establish a wind damage prediction model. As the dependent variable, we used the value of the Texas Windstorm Insurance Association (TWIA claim payout divided by the appraised values of the buildings to predict real economic loss. As independent variables, we selected a hurricane indicator and built environment vulnerability indicators. The model we developed can be used by government agencies and insurance companies to predict hurricane wind damage.

  14. Intelligent and robust prediction of short term wind power using genetic programming based ensemble of neural networks

    International Nuclear Information System (INIS)

    Zameer, Aneela; Arshad, Junaid; Khan, Asifullah; Raja, Muhammad Asif Zahoor

    2017-01-01

    Highlights: • Genetic programming based ensemble of neural networks is employed for short term wind power prediction. • Proposed predictor shows resilience against abrupt changes in weather. • Genetic programming evolves nonlinear mapping between meteorological measures and wind-power. • Proposed approach gives mathematical expressions of wind power to its independent variables. • Proposed model shows relatively accurate and steady wind-power prediction performance. - Abstract: The inherent instability of wind power production leads to critical problems for smooth power generation from wind turbines, which then requires an accurate forecast of wind power. In this study, an effective short term wind power prediction methodology is presented, which uses an intelligent ensemble regressor that comprises Artificial Neural Networks and Genetic Programming. In contrast to existing series based combination of wind power predictors, whereby the error or variation in the leading predictor is propagated down the stream to the next predictors, the proposed intelligent ensemble predictor avoids this shortcoming by introducing Genetical Programming based semi-stochastic combination of neural networks. It is observed that the decision of the individual base regressors may vary due to the frequent and inherent fluctuations in the atmospheric conditions and thus meteorological properties. The novelty of the reported work lies in creating ensemble to generate an intelligent, collective and robust decision space and thereby avoiding large errors due to the sensitivity of the individual wind predictors. The proposed ensemble based regressor, Genetic Programming based ensemble of Artificial Neural Networks, has been implemented and tested on data taken from five different wind farms located in Europe. Obtained numerical results of the proposed model in terms of various error measures are compared with the recent artificial intelligence based strategies to demonstrate the

  15. Short-term load and wind power forecasting using neural network-based prediction intervals.

    Science.gov (United States)

    Quan, Hao; Srinivasan, Dipti; Khosravi, Abbas

    2014-02-01

    Electrical power systems are evolving from today's centralized bulk systems to more decentralized systems. Penetrations of renewable energies, such as wind and solar power, significantly increase the level of uncertainty in power systems. Accurate load forecasting becomes more complex, yet more important for management of power systems. Traditional methods for generating point forecasts of load demands cannot properly handle uncertainties in system operations. To quantify potential uncertainties associated with forecasts, this paper implements a neural network (NN)-based method for the construction of prediction intervals (PIs). A newly introduced method, called lower upper bound estimation (LUBE), is applied and extended to develop PIs using NN models. A new problem formulation is proposed, which translates the primary multiobjective problem into a constrained single-objective problem. Compared with the cost function, this new formulation is closer to the primary problem and has fewer parameters. Particle swarm optimization (PSO) integrated with the mutation operator is used to solve the problem. Electrical demands from Singapore and New South Wales (Australia), as well as wind power generation from Capital Wind Farm, are used to validate the PSO-based LUBE method. Comparative results show that the proposed method can construct higher quality PIs for load and wind power generation forecasts in a short time.

  16. Pressure integration technique for predicting wind-induced response in high-rise buildings

    Directory of Open Access Journals (Sweden)

    Aly Mousaad Aly

    2013-12-01

    Full Text Available This paper presents a procedure for response prediction in high-rise buildings under wind loads. The procedure is illustrated in an application example of a tall building exposed to both cross-wind and along-wind loads. The responses of the building in the lateral directions combined with torsion are estimated simultaneously. Results show good agreement with recent design standards; however, the proposed procedure has the advantages of accounting for complex mode shapes, non-uniform mass distribution, and interference effects from the surrounding. In addition, the technique allows for the contribution of higher modes. For accurate estimation of the acceleration response, it is important to consider not only the first two lateral vibrational modes, but also higher modes. Ignoring the contribution of higher modes may lead to underestimation of the acceleration response; on the other hand, it could result in overestimation of the displacement response. Furthermore, the procedure presented in this study can help decision makers, involved in a tall building design/retrofit to choose among innovative solutions like aerodynamic mitigation, structural member size adjustment, damping enhancement, and/or materials change, with an objective to improve the resiliency and the serviceability under extreme wind actions.

  17. Predicting wind-induced vibrations of high-rise buildings using unsteady CFD and modal analysis

    KAUST Repository

    Zhang, Yue

    2015-01-01

    This paper investigates the wind-induced vibration of the CAARC standard tall building model, via unsteady Computational Fluid Dynamics (CFD) and a structural modal analysis. In this numerical procedure, the natural unsteady wind in the atmospheric boundary layer is modeled with an artificial inflow turbulence generation method. Then, the turbulent flow is simulated by the second mode of a Zonal Detached-Eddy Simulation, and a conservative quadrature-projection scheme is adopted to transfer unsteady loads from fluid to structural nodes. The aerodynamic damping that represents the fluid-structure interaction mechanism is determined by empirical functions extracted from wind tunnel experiments. Eventually, the flow solutions and the structural responses in terms of mean and root mean square quantities are compared with experimental measurements, over a wide range of reduced velocities. The significance of turbulent inflow conditions and aeroelastic effects is highlighted. The current methodology provides predictions of good accuracy and can be considered as a preliminary design tool to evaluate the unsteady wind effects on tall buildings.

  18. Improving Wind Farm Dispatchability Using Model Predictive Control for Optimal Operation of Grid-Scale Energy Storage

    Directory of Open Access Journals (Sweden)

    Douglas Halamay

    2014-09-01

    Full Text Available This paper demonstrates the use of model-based predictive control for energy storage systems to improve the dispatchability of wind power plants. Large-scale wind penetration increases the variability of power flow on the grid, thus increasing reserve requirements. Large energy storage systems collocated with wind farms can improve dispatchability of the wind plant by storing energy during generation over-the-schedule and sourcing energy during generation under-the-schedule, essentially providing on-site reserves. Model predictive control (MPC provides a natural framework for this application. By utilizing an accurate energy storage system model, control actions can be planned in the context of system power and state-of-charge limitations. MPC also enables the inclusion of predicted wind farm performance over a near-term horizon that allows control actions to be planned in anticipation of fast changes, such as wind ramps. This paper demonstrates that model-based predictive control can improve system performance compared with a standard non-predictive, non-model-based control approach. It is also demonstrated that secondary objectives, such as reducing the rate of change of the wind plant output (i.e., ramps, can be considered and successfully implemented within the MPC framework. Specifically, it is shown that scheduling error can be reduced by 81%, reserve requirements can be improved by up to 37%, and the number of ramp events can be reduced by 74%.

  19. Optimal Active Power Control of A Wind Farm Equipped with Energy Storage System based on Distributed Model Predictive Control

    DEFF Research Database (Denmark)

    Zhao, Haoran; Wu, Qiuwei; Guo, Qinglai

    2016-01-01

    This paper presents the Distributed Model Predictive Control (D-MPC) of a wind farm equipped with fast and short-term Energy Storage System (ESS) for optimal active power control using the fast gradient method via dual decomposition. The primary objective of the D-MPC control of the wind farm...... is power reference tracking from system operators. Besides, by optimal distribution of the power references to individual wind turbines and the ESS unit, the wind turbine mechanical loads are alleviated. With the fast gradient method, the convergence rate of the DMPC is significantly improved which leads...

  20. On-Line Flutter Prediction Tool for Wind Tunnel Flutter Testing using Parameter Varying Estimation Methodology, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — ZONA Technology, Inc. (ZONA) proposes to develop an on-line flutter prediction tool for wind tunnel model using the parameter varying estimation (PVE) technique to...

  1. Current error vector based prediction control of the section winding permanent magnet linear synchronous motor

    Energy Technology Data Exchange (ETDEWEB)

    Hong Junjie, E-mail: hongjjie@mail.sysu.edu.cn [School of Engineering, Sun Yat-Sen University, Guangzhou 510006 (China); Li Liyi, E-mail: liliyi@hit.edu.cn [Dept. Electrical Engineering, Harbin Institute of Technology, Harbin 150000 (China); Zong Zhijian; Liu Zhongtu [School of Engineering, Sun Yat-Sen University, Guangzhou 510006 (China)

    2011-10-15

    Highlights: {yields} The structure of the permanent magnet linear synchronous motor (SW-PMLSM) is new. {yields} A new current control method CEVPC is employed in this motor. {yields} The sectional power supply method is different to the others and effective. {yields} The performance gets worse with voltage and current limitations. - Abstract: To include features such as greater thrust density, higher efficiency without reducing the thrust stability, this paper proposes a section winding permanent magnet linear synchronous motor (SW-PMLSM), whose iron core is continuous, whereas winding is divided. The discrete system model of the motor is derived. With the definition of the current error vector and selection of the value function, the theory of the current error vector based prediction control (CEVPC) for the motor currents is explained clearly. According to the winding section feature, the motion region of the mover is divided into five zones, in which the implementation of the current predictive control method is proposed. Finally, the experimental platform is constructed and experiments are carried out. The results show: the current control effect has good dynamic response, and the thrust on the mover remains constant basically.

  2. Using Deep Learning to Predict Complex Systems: A Case Study in Wind Farm Generation

    Directory of Open Access Journals (Sweden)

    J. M. Torres

    2018-01-01

    Full Text Available Making every component of an electrical system work in unison is being made more challenging by the increasing number of renewable energies used, the electrical output of which is difficult to determine beforehand. In Spain, the daily electricity market opens with a 12-hour lead time, where the supply and demand expected for the following 24 hours are presented. When estimating the generation, energy sources like nuclear are highly stable, while peaking power plants can be run as necessary. Renewable energies, however, which should eventually replace peakers insofar as possible, are reliant on meteorological conditions. In this paper we propose using different deep-learning techniques and architectures to solve the problem of predicting wind generation in order to participate in the daily market, by making predictions 12 and 36 hours in advance. We develop and compare various estimators based on feedforward, convolutional, and recurrent neural networks. These estimators were trained and validated with data from a wind farm located on the island of Tenerife. We show that the best candidates for each type are more precise than the reference estimator and the polynomial regression currently used at the wind farm. We also conduct a sensitivity analysis to determine which estimator type is most robust to perturbations. An analysis of our findings shows that the most accurate and robust estimators are those based on feedforward neural networks with a SELU activation function and convolutional neural networks.

  3. An Initial Assessment of the Impact of CYGNSS Ocean Surface Wind Assimilation on Navy Global and Mesoscale Numerical Weather Prediction

    Science.gov (United States)

    Baker, N. L.; Tsu, J.; Swadley, S. D.

    2017-12-01

    We assess the impact of assimilation of CYclone Global Navigation Satellite System (CYGNSS) ocean surface winds observations into the NAVGEM[i] global and COAMPS®[ii] mesoscale numerical weather prediction (NWP) systems. Both NAVGEM and COAMPS® used the NRL 4DVar assimilation system NAVDAS-AR[iii]. Long term monitoring of the NAVGEM Forecast Sensitivity Observation Impact (FSOI) indicates that the forecast error reduction for ocean surface wind vectors (ASCAT and WindSat) are significantly larger than for SSMIS wind speed observations. These differences are larger than can be explained by simply two pieces of information (for wind vectors) versus one (wind speed). To help understand these results, we conducted a series of Observing System Experiments (OSEs) to compare the assimilation of ASCAT wind vectors with the equivalent (computed) ASCAT wind speed observations. We found that wind vector assimilation was typically 3 times more effective at reducing the NAVGEM forecast error, with a higher percentage of beneficial observations. These results suggested that 4DVar, in the absence of an additional nonlinear outer loop, has limited ability to modify the analysis wind direction. We examined several strategies for assimilating CYGNSS ocean surface wind speed observations. In the first approach, we assimilated CYGNSS as wind speed observations, following the same methodology used for SSMIS winds. The next two approaches converted CYGNSS wind speed to wind vectors, using NAVGEM sea level pressure fields (following Holton, 1979), and using NAVGEM 10-m wind fields with the AER Variational Analysis Method. Finally, we compared these methods to CYGNSS wind speed assimilation using multiple outer loops with NAVGEM Hybrid 4DVar. Results support the earlier studies suggesting that NAVDAS-AR wind speed assimilation is sub-optimal. We present detailed results from multi-month NAVGEM assimilation runs along with case studies using COAMPS®. Comparisons include the fit of

  4. Erosive gastritis

    International Nuclear Information System (INIS)

    Mohammed, S.H.; Conrad, C.; Kjoergaad, J.

    1982-01-01

    Erosive gastritis is a well-defined radiologic and endoscopic entity. It is one of the common causes of upper gastrointestinal bleeding, yet it is seldom diagnosed and often confused with a number of other diseases. This communication re-emphasizes the characteristic endoscopic and radiologic features of erosive gastritis and its differential diagnosis. Two representative cases are reported. (orig.)

  5. Erosive gastritis

    Energy Technology Data Exchange (ETDEWEB)

    Mohammed, S.H.; Conrad, C.; Kjoergaad, J.

    1982-08-01

    Erosive gastritis is a well-defined radiologic and endoscopic entity. It is one of the common causes of upper gastrointestinal bleeding, yet it is seldom diagnosed and often confused with a number of other diseases. This communication re-emphasizes the characteristic endoscopic and radiologic features of erosive gastritis and its differential diagnosis. Two representative cases are reported.

  6. Predictive control strategies for wind turbine system based on permanent magnet synchronous generator.

    Science.gov (United States)

    Maaoui-Ben Hassine, Ikram; Naouar, Mohamed Wissem; Mrabet-Bellaaj, Najiba

    2016-05-01

    In this paper, Model Predictive Control and Dead-beat predictive control strategies are proposed for the control of a PMSG based wind energy system. The proposed MPC considers the model of the converter-based system to forecast the possible future behavior of the controlled variables. It allows selecting the voltage vector to be applied that leads to a minimum error by minimizing a predefined cost function. The main features of the MPC are low current THD and robustness against parameters variations. The Dead-beat predictive control is based on the system model to compute the optimum voltage vector that ensures zero-steady state error. The optimum voltage vector is then applied through Space Vector Modulation (SVM) technique. The main advantages of the Dead-beat predictive control are low current THD and constant switching frequency. The proposed control techniques are presented and detailed for the control of back-to-back converter in a wind turbine system based on PMSG. Simulation results (under Matlab-Simulink software environment tool) and experimental results (under developed prototyping platform) are presented in order to show the performances of the considered control strategies. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

  7. Numerical Prediction for the Size and Shape of a Flare in a Cross–Wind

    Directory of Open Access Journals (Sweden)

    W. Vicente y Rodríguez

    2009-10-01

    Full Text Available A computational fluid–dynamics model is used to simulate the turbulent combustion in a flare exposed to a cross–wind. Our research is mostly focused on the cross flow velocity influence to flame aerodynamics. The flow simulation is performed as three dimensional along a Cartesian coordinates system. In order to simulate the combustion process, a fast–chemistry model with a 1–step global irreversible reaction to form CO2 and H2O is used. A radiation model is used to identify the mean flame trajectory. The simulated configuration consists in a propane discharge into an air stream, get ting oxygen supply from the cross–wind. The velocity of this cross–flow is increased from 0.8 m/s to 12 m/s. Comparative analysis of our predicted values with respect to available experimental results shows good agreement in terms of flame length as well as inclination angles.

  8. Real time simulation of nonlinear generalized predictive control for wind energy conversion system with nonlinear observer.

    Science.gov (United States)

    Ouari, Kamel; Rekioua, Toufik; Ouhrouche, Mohand

    2014-01-01

    In order to make a wind power generation truly cost-effective and reliable, an advanced control techniques must be used. In this paper, we develop a new control strategy, using nonlinear generalized predictive control (NGPC) approach, for DFIG-based wind turbine. The proposed control law is based on two points: NGPC-based torque-current control loop generating the rotor reference voltage and NGPC-based speed control loop that provides the torque reference. In order to enhance the robustness of the controller, a disturbance observer is designed to estimate the aerodynamic torque which is considered as an unknown perturbation. Finally, a real-time simulation is carried out to illustrate the performance of the proposed controller. Copyright © 2013 ISA. Published by Elsevier Ltd. All rights reserved.

  9. Creep life prediction of super heater coils used in coal based thermal power plants subjected to fly ash erosion and oxide scale formation

    Science.gov (United States)

    Srinivasan, P.; Kushwaha, Shashank

    2018-04-01

    Super heater coils of the coal based thermal power plants and subjected to severe operating conditions from both steam side and gas side. Formation of oxide scale due to prolonged service lead to temperature raise of the tube and erosion due to fly ash present in the combusted gases leads to tube thinning. Both these factors lead to creep rupture of the coils much before the designed service life. Failure of super heater coils during service of the boiler leads to power loss and huge monitory loss to the power plants. An attempt is made to model the creep damage caused to the super heater coils using heat transfer analysis tube thinning due to erosive wear of the tubes. Combined effects of these parameters are taken into consideration to predict the life of the super heater coils. This model may be used to estimate the life of the coils operating under the severe operating conditions to prevent the unexpected failure of the coils.

  10. Numerical Predictions of Wind Turbine Power and Aerodynamic Loads for the NREL Phase II and IV Combined Experiment Rotor

    Science.gov (United States)

    Duque, Earl P. N.; Johnson, Wayne; vanDam, C. P.; Chao, David D.; Cortes, Regina; Yee, Karen

    1999-01-01

    Accurate, reliable and robust numerical predictions of wind turbine rotor power remain a challenge to the wind energy industry. The literature reports various methods that compare predictions to experiments. The methods vary from Blade Element Momentum Theory (BEM), Vortex Lattice (VL), to variants of Reynolds-averaged Navier-Stokes (RaNS). The BEM and VL methods consistently show discrepancies in predicting rotor power at higher wind speeds mainly due to inadequacies with inboard stall and stall delay models. The RaNS methodologies show promise in predicting blade stall. However, inaccurate rotor vortex wake convection, boundary layer turbulence modeling and grid resolution has limited their accuracy. In addition, the inherently unsteady stalled flow conditions become computationally expensive for even the best endowed research labs. Although numerical power predictions have been compared to experiment. The availability of good wind turbine data sufficient for code validation experimental data that has been extracted from the IEA Annex XIV download site for the NREL Combined Experiment phase II and phase IV rotor. In addition, the comparisons will show data that has been further reduced into steady wind and zero yaw conditions suitable for comparisons to "steady wind" rotor power predictions. In summary, the paper will present and discuss the capabilities and limitations of the three numerical methods and make available a database of experimental data suitable to help other numerical methods practitioners validate their own work.

  11. Coupling a Mesoscale Numerical Weather Prediction Model with Large-Eddy Simulation for Realistic Wind Plant Aerodynamics Simulations (Poster)

    Energy Technology Data Exchange (ETDEWEB)

    Draxl, C.; Churchfield, M.; Mirocha, J.; Lee, S.; Lundquist, J.; Michalakes, J.; Moriarty, P.; Purkayastha, A.; Sprague, M.; Vanderwende, B.

    2014-06-01

    Wind plant aerodynamics are influenced by a combination of microscale and mesoscale phenomena. Incorporating mesoscale atmospheric forcing (e.g., diurnal cycles and frontal passages) into wind plant simulations can lead to a more accurate representation of microscale flows, aerodynamics, and wind turbine/plant performance. Our goal is to couple a numerical weather prediction model that can represent mesoscale flow [specifically the Weather Research and Forecasting model] with a microscale LES model (OpenFOAM) that can predict microscale turbulence and wake losses.

  12. Predicting Effects of Corrosion Erosion of High Strength Steel Pipelines Elbow on CO2-Acetic Acid (HAc) Solution

    International Nuclear Information System (INIS)

    Asmara, Y. P.; Ismail, M. F.; Chui, L. Giok; Halimi, Jamiludin

    2016-01-01

    Simultaneously effect of erosion combined with corrosion becomes the most concern in oil and gas industries. It is due to the fast deterioration of metal as effects of solid particles mixed with corrosive environment. There are many corrosion software to investigate possible degradation mechanisms developed by researchers. They are using many combination factors of chemical reactions and physical process. However effects of CO 2 and acid on pipelines orientations are still remain uncovered in their simulation. This research will investigate combination effects of CO 2 and HAc on corrosion and erosion artificial environmental containing sands particles in 45°, 90° and 180° elbow pipelines. The research used theoretical calculations combined with experiments for verification. The main concerns are to investigate the maximum erosion corrosion rate and maximum shear stress at the surface. Methodology used to calculate corrosion rate are Linear Polarization Resistance (LPR) and weight loss. The results showed that at 45°, erosion rate is the more significant effects in contributing degradation of the metal. The effects of CO 2 and HAc gave significant effects when flow rate of the solution are high which reflect synergism effects of solid particles and those chemical compositions. (paper)

  13. Observations and Predictions of Wave Runup, Extreme Water Levels, and Medium-Term Dune Erosion during Storm Conditions

    Directory of Open Access Journals (Sweden)

    Serge Suanez

    2015-07-01

    Full Text Available Monitoring of dune erosion and accretion on the high-energy macrotidal Vougot beach in North Brittany (France over the past decade (2004–2014 has revealed significant morphological changes. Dune toe erosion/accretion records have been compared with extreme water level measurements, defined as the sum of (i astronomic tide; (ii storm surge; and (iii vertical wave runup. Runup parameterization was conducted using swash limits, beach profiles, and hydrodynamic (Hm0, Tm0,–1, and high tide water level—HTWL data sets obtained from high frequency field surveys. The aim was to quantify in-situ environmental conditions and dimensional swash parameters for the best calibration of Battjes [1] runup formula. In addition, an empirical equation based on observed tidal water level and offshore wave height was produced to estimate extreme water levels over the whole period of dune morphological change monitoring. A good correlation between this empirical equation (1.01Hmoξo and field runup measurements (Rmax was obtained (R2 85%. The goodness of fit given by the RMSE was about 0.29 m. A good relationship was noticed between dune erosion and high water levels when the water levels exceeded the dune foot elevation. In contrast, when extreme water levels were below the height of the toe of the dune sediment budget increased, inducing foredune recovery. These erosion and accretion phases may be related to the North Atlantic Oscillation Index.

  14. A pan-European quantitative assessment of soil loss by wind

    Science.gov (United States)

    Borrelli, Pasqualle; Lugato, Emanuele; Panagos, Panos

    2016-04-01

    Soil erosion by wind is a serious environmental problem often low perceived but resulting in severe soil degradation forms. On the long-term a considerable part of topsoil - rich in nutrient and organic matters - could be removed compromising the agricultural productivity and inducing an increased use of fertilizers. Field scale studies and observations proven that wind erosion is a serious problem in many European sites. The state-of-the-art suggests a scenario where wind erosion locally affects the temperate climate areas of the northern European countries, as well as the semi-arid areas of the Mediterranean region. However, observations, field measurements and modelling assessments are extremely limited and unequally distributed across Europe. It implies a lack of knowledge about where and when wind erosion occurs, limiting policy actions aimed at mitigating land degradation. To gain a better understanding about soil degradation process, the Soil Resource Assessment working group of the Joint Research Centre carried out the first pan-European assessments of wind-erodible fraction of soil (EF) (Geoderma, 232, 471-478, 2014) and land susceptibility to wind erosion (Land Degradation & Development, DOI: 10.1002/ldr.2318). Today's challenge is to integrate the insights archived by these pan-European assessments, local experiments and field-scale models into a new generation of regional-scale wind erosion models. A GIS version of the Revised Wind Erosion Equation (RWEQ) was developed with the aim to i) move a step forward into the aforementioned challenges, and ii) evaluate the soil loss potential due to wind erosion in the agricoltural land of the EU. The model scheme was designed to describe daily soil loss potential, combining spatiotemporal conditions of soil erodibility, crust factor, soil moisture content, vegetation coverage and wind erosivity at 1 km2 resolution. The average soil loss predicted by GIS-RWEQ in the EU arable land ranges from 0 to 39.9 Mg ha-1 yr

  15. Gain-Scheduled Model Predictive Control of Wind Turbines using Laguerre Functions

    DEFF Research Database (Denmark)

    Adegas, Fabiano Daher; Wisniewski, Rafal; Larsen, Lars Finn Sloth

    2014-01-01

    This paper presents a systematic approach to design gain-scheduled predictive controllers for wind turbines. The predictive control law is based on Laguerre functions to parameterize control signals and a parameter-dependent cost function that is analytically determined from turbine data....... These properties facilitate the design of speed controllers by placement of the closed-loop poles (when constraints are not active) and systematic adaptation towards changes in the operating point. Vibration control of undamped modes is achieved by imposing a certain degree of stability to the closed-loop system....... The approach can be utilized to the design of new controllers and to represent existing gain-scheduled controllers as predictive controllers. The numerical example and simulations illustrate the design of a speed controller augmented with active damping of the tower fore-aft displacement....

  16. Short term prediction of the horizontal wind vector within a wake vortex warning system

    Energy Technology Data Exchange (ETDEWEB)

    Frech, M.; Holzaepfel, F.; Gerz, T. [DLR Deutsches Zentrum fuer Luft- und Raumfahrt e.V., Wessling (Germany). Inst. fuer Physik der Atmosphaere; Konopka, J. [Deutsche Flugsicherung (DFS) GmbH, Langen (Germany)

    2000-07-14

    A wake vortex warning system (WVWS) has been developed for Frankfurt airport. This airport has two parallel runways which are separated by 518 m, a distance too short to operate them independently because wake vortices may be advected to the adjacent runway. The objective of the WVWS is to enable operation with reduced separation between two aircraft approaching the parallel runways at appropriate wind conditions. The WVWS applies a statistical persistence model to predict the crosswind within a 20 minute period. One of the main problems identified in the old WVWS are discontinuities between successive forecasts. These forecast breakdowns were not acceptable to airtraffic controllers. At least part of the problem was related to the fact that the forecast was solely based on the prediction of crosswind. A new method is developed on the basis of 523 days of sonic anemometer measurements at Frankfurt airport. It is demonstrated that the prediction of the horizontal wind vector avoids these difficulties and significantly improves the system's performance. (orig.)

  17. Frequency-Weighted Model Predictive Control of Trailing Edge Flaps on a Wind Turbine Blade

    DEFF Research Database (Denmark)

    Castaignet, Damien; Couchman, Ian; Poulsen, Niels Kjølstad

    2013-01-01

    flapwise blade root moment and trailing edge flap deflection. Frequency-weighted MPC is chosen for its ability to handle constraints on the trailing edge flaps deflection, and to target at loads with given frequencies only. The controller is first tested in servo-aeroelastic simulations, before being......This paper presents the load reduction achieved with trailing edge flaps during a full-scale test on a Vestas V27 wind turbine. The trailing edge flap controller is a frequency-weighted linear model predictive control (MPC) where the quadratic cost consists of costs on the zero-phase filtered...

  18. Ability of One-Dimensional Hairsine-Rose Erosion Model to Predict Sediment Transport over a Soil with Significant Surface Stones

    Science.gov (United States)

    Jomaa, S.; Barry, D. A.; Sander, G. C.; Parlange, J.-Y.; Heng, B. C. P.; Tromp-van Meerveld, H. J.

    2010-05-01

    Surface stones affect erosion rates by reducing raindrop-driven detachment and protecting the original soil against overland flow induced-hydraulic stress. Numerous studies have shown that the effect of surface stones on erosion depends on both the stone characteristics (e.g., size, distribution) and the soil properties. The aim of this study was (i) to quantify how the stone characteristics can affect the total sediment concentration and the concentrations of the individual size classes, (ii) to test if stones affect preferentially a particular size class within the eroded sediment and (iii) to determine whether the 1D Hairsine-Rose (H-R) erosion model can represent the experimental data. A series of laboratory experiments were conducted using the 2 m × 6 m EPFL erosion flume for a high rainfall intensity (60 mm/h) event on a gentle slope (2.2%). The flume was divided into two identical 1-m wide flumes. This separation was done to allow simultaneous replicate experiments. Experiments were conducted with different configurations and scenarios (stone coverage, size and emplacement). Three coverage proportions (20%, 40%, and 70%), two stone diameters (3-4 and 6-7 cm) and two emplacement types (topsoil and partially embedded) were tested. For each experiment, the total sediment concentration, the concentration for the individual size classes, and the flume discharge were measured. Infiltration rates were measured at different depths and locations. A high resolution laser scanner provided details of the surface change due to erosion during the experiments. This technique allowed us to quantify the spatial distribution of eroded soil and to understand better if sediment transport is 1D or rather 2D over the flumes. The one-dimensional Hairsine-Rose (H-R) erosion model was used to fit the integrated data and to provide estimates of the parameters. The ability of the 1D H-R model to predict the measured sediment concentrations in the presence of stones in the soil matrix

  19. High resolution modelling of wind fields for optimization of empirical storm flood predictions

    Science.gov (United States)

    Brecht, B.; Frank, H.

    2014-05-01

    High resolution wind fields are necessary to predict the occurrence of storm flood events and their magnitude. Deutscher Wetterdienst (DWD) created a catalogue of detailed wind fields of 39 historical storms at the German North Sea coast from the years 1962 to 2011. The catalogue is used by the Niedersächsisches Landesamt für Wasser-, Küsten- und Naturschutz (NLWKN) coastal research center to improve their flood alert service. The computation of wind fields and other meteorological parameters is based on the model chain of the DWD going from the global model GME via the limited-area model COSMO with 7 km mesh size down to a COSMO model with 2.2 km. To obtain an improved analysis COSMO runs are nudged against observations for the historical storms. The global model GME is initialised from the ERA reanalysis data of the European Centre for Medium-Range Weather Forecasts (ECMWF). As expected, we got better congruency with observations of the model for the nudging runs than the normal forecast runs for most storms. We also found during the verification process that different land use data sets could influence the results considerably.

  20. Loading Analysis of Composite Wind Turbine Blade for Fatigue Life Prediction of Adhesively Bonded Root Joint

    Science.gov (United States)

    Salimi-Majd, Davood; Azimzadeh, Vahid; Mohammadi, Bijan

    2015-06-01

    Nowadays wind energy is widely used as a non-polluting cost-effective renewable energy resource. During the lifetime of a composite wind turbine which is about 20 years, the rotor blades are subjected to different cyclic loads such as aerodynamics, centrifugal and gravitational forces. These loading conditions, cause to fatigue failure of the blade at the adhesively bonded root joint, where the highest bending moments will occur and consequently, is the most critical zone of the blade. So it is important to estimate the fatigue life of the root joint. The cohesive zone model is one of the best methods for prediction of initiation and propagation of debonding at the root joint. The advantage of this method is the possibility of modeling the debonding without any requirement to the remeshing. However in order to use this approach, it is necessary to analyze the cyclic loading condition at the root joint. For this purpose after implementing a cohesive interface element in the Ansys finite element software, one blade of a horizontal axis wind turbine with 46 m rotor diameter was modelled in full scale. Then after applying loads on the blade under different condition of the blade in a full rotation, the critical condition of the blade is obtained based on the delamination index and also the load ratio on the root joint in fatigue cycles is calculated. These data are the inputs for fatigue damage growth analysis of the root joint by using CZM approach that will be investigated in future work.

  1. Drivers and seasonal predictability of extreme wind speeds in the ECMWF System 4 and a statistical model

    Science.gov (United States)

    Walz, M. A.; Donat, M.; Leckebusch, G. C.

    2017-12-01

    As extreme wind speeds are responsible for large socio-economic losses in Europe, a skillful prediction would be of great benefit for disaster prevention as well as for the actuarial community. Here we evaluate patterns of large-scale atmospheric variability and the seasonal predictability of extreme wind speeds (e.g. >95th percentile) in the European domain in the dynamical seasonal forecast system ECMWF System 4, and compare to the predictability based on a statistical prediction model. The dominant patterns of atmospheric variability show distinct differences between reanalysis and ECMWF System 4, with most patterns in System 4 extended downstream in comparison to ERA-Interim. The dissimilar manifestations of the patterns within the two models lead to substantially different drivers associated with the occurrence of extreme winds in the respective model. While the ECMWF System 4 is shown to provide some predictive power over Scandinavia and the eastern Atlantic, only very few grid cells in the European domain have significant correlations for extreme wind speeds in System 4 compared to ERA-Interim. In contrast, a statistical model predicts extreme wind speeds during boreal winter in better agreement with the observations. Our results suggest that System 4 does not seem to capture the potential predictability of extreme winds that exists in the real world, and therefore fails to provide reliable seasonal predictions for lead months 2-4. This is likely related to the unrealistic representation of large-scale patterns of atmospheric variability. Hence our study points to potential improvements of dynamical prediction skill by improving the simulation of large-scale atmospheric dynamics.

  2. Upper Gastrointestinal Symptoms Predictive of Candida Esophagitis and Erosive Esophagitis in HIV and Non-HIV Patients: An Endoscopy-Based Cross-Sectional Study of 6011 Patients.

    Science.gov (United States)

    Takahashi, Yuta; Nagata, Naoyoshi; Shimbo, Takuro; Nishijima, Takeshi; Watanabe, Koji; Aoki, Tomonori; Sekine, Katsunori; Okubo, Hidetaka; Watanabe, Kazuhiro; Sakurai, Toshiyuki; Yokoi, Chizu; Mimori, Akio; Oka, Shinichi; Uemura, Naomi; Akiyama, Junichi

    2015-11-01

    Upper gastrointestinal (GI) symptoms are common in both HIV and non-HIV-infected patients, but the difference of GI symptom severity between 2 groups remains unknown. Candida esophagitis and erosive esophagitis, 2 major types of esophagitis, are seen in both HIV and non-HIV-infected patients, but differences in GI symptoms that are predictive of esophagitis between 2 groups remain unknown. We aimed to determine whether GI symptoms differ between HIV-infected and non-HIV-infected patients, and identify specific symptoms of candida esophagitis and erosive esophagitis between 2 groups.We prospectively enrolled 6011 patients (HIV, 430; non-HIV, 5581) who underwent endoscopy and completed questionnaires. Nine upper GI symptoms (epigastric pain, heartburn, acid regurgitation, hunger cramps, nausea, early satiety, belching, dysphagia, and odynophagia) were evaluated using a 7-point Likert scale. Associations between esophagitis and symptoms were analyzed by the multivariate logistic regression model adjusted for age, sex, and proton pump inhibitors.Endoscopy revealed GI-organic diseases in 33.4% (2010/6.011) of patients. The prevalence of candida esophagitis and erosive esophagitis was 11.2% and 12.1% in HIV-infected patients, respectively, whereas it was 2.9% and 10.7 % in non-HIV-infected patients, respectively. After excluding GI-organic diseases, HIV-infected patients had significantly (P symptom scores for heartburn, hunger cramps, nausea, early satiety, belching, dysphagia, and odynophagia than non-HIV-infected patients. In HIV-infected patients, any symptom was not significantly associated with CD4 cell count. In multivariate analysis, none of the 9 GI symptoms were associated with candida esophagitis in HIV-infected patients, whereas dysphagia and odynophagia were independently (P HIV-infected patients. However, heartburn and acid regurgitation were independently (P symptom scores were reliable in both HIV (α, 0.86) and non-HIV-infected patients (α, 0.85).This

  3. Wind directions predicted from global circulation models and wind directions determined from eolian sandstones of the western United States-A comparison

    Science.gov (United States)

    Parrish, Judith T.; Peterson, F.

    1988-01-01

    Wind directions for Middle Pennsylvanian through Jurassic time are predicted from global circulation models for the western United States. These predictions are compared with paleowind directions interpreted from eolian sandstones of Middle Pennsylvanian through Jurassic age. Predicted regional wind directions correspond with at least three-quarters of the paleowind data from the sandstones; the rest of the data may indicate problems with correlation, local effects of paleogeography on winds, and lack of resolution of the circulation models. The data and predictions suggest the following paleoclimatic developments through the time interval studied: predominance of winter subtropical high-pressure circulation in the Late Pennsylvanian; predominance of summer subtropical high-pressure circulation in the Permian; predominance of summer monsoonal circulation in the Triassic and earliest Jurassic; and, during the remainder of the Jurassic, influence of both summer subtropical and summer monsoonal circulation, with the boundary between the two systems over the western United States. This sequence of climatic changes is largely owing to paleogeographic changes, which influenced the buildup and breakdown of the monsoonal circulation, and possibly owing partly to a decrease in the global temperature gradient, which might have lessened the influence of the subtropical high-pressure circulation. The atypical humidity of Triassic time probably resulted from the monsoonal circulation created by the geography of Pangaea. This circulation is predicted to have been at a maximum in the Triassic and was likely to have been powerful enough to draw moisture along the equator from the ocean to the west. ?? 1988.

  4. The use of different ensemble forecasting systems for wind power prediction on a real case in the South of Italy

    DEFF Research Database (Denmark)

    Alessandrini, Stefano; Sperati, Simone; Pinson, Pierre

    2012-01-01

    Short-term forecasting applied to wind energy is becoming increasingly important due to the constant growth of this renewable source, whose uncertainty requires a constant effort to meet the needs of the national electrical systems and their operators. Regarding to this, the probabilistic approach...... calibration performed on the wind speed EPS members allows an improvement from an over-confident situation observable from the rank histograms (in which the measurements fell quite always outside the bounds of the probability distribution) to a consistent ensemble spread. After that it is possible to convert...... the data to wind energy: the spread calculated on wind power can then be used as an accuracy predictor due to its level of correlation with the deterministic WPF error. In this presentation we investigate the performances for both wind power and accuracy prediction of the new EPS used at the ECMWF, whose...

  5. Estimation Model of Soil Freeze-Thaw Erosion in Silingco Watershed Wetland of Northern Tibet

    OpenAIRE

    Kong, Bo; Yu, Huan

    2013-01-01

    The freeze-thaw (FT) erosion is a type of soil erosion like water erosion and wind erosion. Limited by many factors, the grading evaluation of soil FT erosion quantities is not well studied. Based on the comprehensive analysis of the evaluation indices of soil FT erosion, we for the first time utilized the sensitivity of microwave remote sensing technology to soil moisture for identification of FT state. We established an estimation model suitable to evaluate the soil FT erosion quantity in S...

  6. Can high-energy proton events in solar wind be predicted via classification of precursory structures?

    Energy Technology Data Exchange (ETDEWEB)

    Hallerberg, Sarah [Chemnitz University of Technology (Germany); Ruzmaikin, Alexander; Feynman, Joan [Jet Propulsion Laboratory, California Institute of Technology (United States)

    2011-07-01

    Shock waves in the solar wind associated with solar coronal mass ejections produce fluxes of high-energy protons and ions with energies larger than 10 MeV. These fluxes present a danger to humans and electronic equipment in space, and also endanger passengers of over-pole air flights. The approaches that have been exploited for the prediction of high-energy particle events so far consist in training artificial neural networks on catalogues of events. Our approach towards this task is based on the identification of precursory structures in the fluxes of particles. In contrast to artificial neural networks that function as a ''black box'' transforming data into predictions, this classification approach can additionally provide information on relevant precursory events and thus might help to improve the understanding of underlying mechanisms of particle acceleration.

  7. Incidencia potencial de la erosión eólica sobre la degradación del suelo y la calidad del aire en distintas regiones de la Argentina Potential effects of wind erosion on soil degradation and air quality in different regions of Argentina

    Directory of Open Access Journals (Sweden)

    Daniel E Buschiazzo

    2009-12-01

    ía relativamente más a la calidad del aire que a la del suelo. La magnitud de este proceso estaría regida, principalmente, por el área disponible para la erosión. En suelos sometidos a manejos agrícolas, frecuentemente desnudos y de bajo grado de evolución como los Ustipsammentes y Haplustoles, la erosión eólica tendría efectos intermedios, afectando tanto a la calidad del suelo como a la del aire. Finalmente, en suelos relativamente más evolucionados y sometidos a manejos agrícolas como los Hapludoles, la erosión afectaría en mayor medida a la calidad del suelo, siendo la emisión de partículas finas de relativa menor importancia.Wind erosion can impact soil and air quality. The magnitude of these effects depends on the soil type and management conditions, and is associated with the transport conditions of soil particles: saltation and rolling affect soil quality to a greater extent while suspension tends to increase the emission of fine particles to the atmosphere. The objective of this research was to determine the magnitude of both type of movements in soils of Argentina, in order to predict potential effects on soil or air quality. This study was carried out in four provinces of Argentina: Chaco (CHA, San Luis (SLU, La Pampa (LPA and Río Negro (PAT. In each case, wind erosion was measured in the 1 ha-square fields by means of BSNE samplers. Results indicated that the total amount of transported material, the so-called mass flux (FM as well as the absolute amount of eroded soil (Q were higher in sites with less developed soils of SLU (Ustipsamment and LPA (Haplustoll and lower in sites with a better developed soil of CHA (Hapludoll or with less developed soil but with permanent soil cover with natural grasses of PAT (Haplargid. Saltation and rolling were the main transport forms in SLU, LPA and CHA and suspension in PAT. Though low (10%, the plant coverage existing in this last site was enough to increase the height of the wind profile and to favor the transport

  8. A Predictive Power Control Strategy for DFIGs Based on a Wind Energy Converter System

    Directory of Open Access Journals (Sweden)

    Xiaoliang Yang

    2017-07-01

    Full Text Available A feasible control strategy is proposed to control a doubly fed induction generator based on the wind energy converter system (DFIG-WECS. The main aim is to enhance the steady state and dynamic performance under the condition of the parameter perturbations and external disturbances and to satisfy the stator power response of the system. Within the proposed control method, the control scheme for the rotor side converter (RSC is developed on the model predictive control. Firstly, the self-adaptive reference trajectory is established from the deduced discrete state-space equation of the generator. Then, the rotor voltage is calculated by minimizing the global performance index under the current prediction steps at the sampling instant. Through the control scheme for the grid side converter (GSC and wind turbine, we have re-applied the conventional control. The effectiveness of the proposed control strategy is verified via time domain simulation of a 150 kW-575 V DFIG-WECS using Matlab/Simulink. The simulation result shows that the control of the DFIG with the proposed control method can enhance the steady and dynamic response capability better than the conventional ones when the system faces errors due to the parameter perturbations, external disturbances and the rotor speed.

  9. Dynamic Modeling and Very Short-term Prediction of Wind Power Output Using Box-Cox Transformation

    Science.gov (United States)

    Urata, Kengo; Inoue, Masaki; Murayama, Dai; Adachi, Shuichi

    2016-09-01

    We propose a statistical modeling method of wind power output for very short-term prediction. The modeling method with a nonlinear model has cascade structure composed of two parts. One is a linear dynamic part that is driven by a Gaussian white noise and described by an autoregressive model. The other is a nonlinear static part that is driven by the output of the linear part. This nonlinear part is designed for output distribution matching: we shape the distribution of the model output to match with that of the wind power output. The constructed model is utilized for one-step ahead prediction of the wind power output. Furthermore, we study the relation between the prediction accuracy and the prediction horizon.

  10. Compressor Impeller Erosion Resistant Surface Treatment

    National Research Council Canada - National Science Library

    Riley, Michael

    2000-01-01

    ...). Coatings based on tungsten carbide tantalum carbide. titanium carbide all with a cobalt matrix were evaluated for high velocity particle erosion in conventional wear test studies as well as wind tunnel testing...

  11. Towards more accurate wind and solar power prediction by improving NWP model physics

    Science.gov (United States)

    Steiner, Andrea; Köhler, Carmen; von Schumann, Jonas; Ritter, Bodo

    2014-05-01

    The growing importance and successive expansion of renewable energies raise new challenges for decision makers, economists, transmission system operators, scientists and many more. In this interdisciplinary field, the role of Numerical Weather Prediction (NWP) is to reduce the errors and provide an a priori estimate of remaining uncertainties associated with the large share of weather-dependent power sources. For this purpose it is essential to optimize NWP model forecasts with respect to those prognostic variables which are relevant for wind and solar power plants. An improved weather forecast serves as the basis for a sophisticated power forecasts. Consequently, a well-timed energy trading on the stock market, and electrical grid stability can be maintained. The German Weather Service (DWD) currently is involved with two projects concerning research in the field of renewable energy, namely ORKA*) and EWeLiNE**). Whereas the latter is in collaboration with the Fraunhofer Institute (IWES), the project ORKA is led by energy & meteo systems (emsys). Both cooperate with German transmission system operators. The goal of the projects is to improve wind and photovoltaic (PV) power forecasts by combining optimized NWP and enhanced power forecast models. In this context, the German Weather Service aims to improve its model system, including the ensemble forecasting system, by working on data assimilation, model physics and statistical post processing. This presentation is focused on the identification of critical weather situations and the associated errors in the German regional NWP model COSMO-DE. First steps leading to improved physical parameterization schemes within the NWP-model are presented. Wind mast measurements reaching up to 200 m height above ground are used for the estimation of the (NWP) wind forecast error at heights relevant for wind energy plants. One particular problem is the daily cycle in wind speed. The transition from stable stratification during

  12. Soil erosion in Iran: Issues and solutions

    Science.gov (United States)

    Hamidreza Sadeghi, Seyed; Cerdà, Artemi

    2015-04-01

    Journal of Geosciences, 7(5), 1941-1950. Khaledi Darvishan, A., Sadeghi, S. H., Homaee, M., Arabkhedri, M. 2013. Measuring sheet erosion using synthetic color-contrast aggregates. Hydrological Processes. Mahmoodabadi, M. Cerdà, A. 2013. WEPP calibration for improved predictions on interril erosion in semi-arid to arid enviorments. Geoderma, 204-205,75-83. http://dx.doi.org/10.1016/j.geoderma.2013.04.013, Mehdizade, B., Asadi, H., Shabanpour, M., Ghadiri, H. 2013. Impact of erosion and tillage on the productivity and quality of selected semiarid soils of Iran. International Agrophysics, 27(3), 291-297. Moghadam, B. K., Jabarifar, M., Bagheri, M., Shahbazi, E. 2015. Effects of land use change on soil splash erosion in the semi-arid region of Iran. Geoderma, 241, 210-220. Nosrati, K., Ahmadi, F. 2013. Monitoring of soil organic carbon and nitrogen stocks in different land use under surface water erosion in a semi-arid drainage basin of Iran. Journal of Applied Sciences and Environmental Management, 17(2), 225-230. Nourzadeh, M., Bahrami, H. A., Goossens, D., Fryrear, D. W. 2013. Determining soil erosion and threshold friction velocity at different soil moisture conditions using a portable wind tunnel. Zeitschrift für Geomorphologie, 57(1), 97-109. Sadeghi, S. H. R., Seghaleh, M. B., Rangavar, A. S. 2013. Plot sizes dependency of runoff and sediment yield estimates from a small watershed. Catena, 102, 55-61. Sadeghi, S. H. R., Seghaleh, M. B., Rangavar, A. S. 2013. Plot sizes dependency of runoff and sediment yield estimates from a small watershed. Catena, 102, 55-61. Sadeghi, S. H., Najafi, S., Riyahi Bakhtiari, A., Abdi, P. 2014. Ascribing soil erosion types for sediment yield using composite fingerprinting technique. Hydrological Sciences Journal, 59(9), 1753-1762. Taghizadeh-Mehrjardi, R., Minasny, B., Sarmadian, F., Malone, B. P. 2014. Digital mapping of soil salinity in Ardakan region, central Iran. Geoderma, 213, 15-28.

  13. Extreme Value Predictions for Wave- and Wind-induced Loads on Floating Offshore Wind Turbines using FORM

    DEFF Research Database (Denmark)

    Joensen, Sunvard; Jensen, Jørgen Juncher; Mansour, Alaa E.

    2007-01-01

    duration of the time domain simulations needed (typically 60-300s to cover the hy-drodynamic memory effects in the response) the calcu-lation of the mean out-crossing rates of a given response are very fast. Thus complicated non-linear effects can be included. The FORM analysis also identifies the most...... probable wave episodes leading to given re-sponses. As an example the motions of floating foundations for offshore wind turbines are analysed taking into consid-eration both the wave and wind induced loads and con-sidering different mooring systems. The possible large horizontal motions make it important...

  14. DEWEPS - Development and Evaluation of new Wind forecasting tools with an Ensemble Prediction System

    Energy Technology Data Exchange (ETDEWEB)

    Moehrlen, C.; Joergensen, Jess

    2012-02-15

    There is an ongoing trend of increased privatization in the handling of renewable energy. This trend is required to ensure an efficient energy system, where improvements that make economic sense are prioritised. The reason why centralized forecasting can be a challenge in that matter is that the TSOs tend to optimize on physical error rather than cost. Consequently, the market is likely to speculate against the TSO, which in turn increases the cost of balancing. A privatized pool of wind and/or solar power is more difficult to speculate against, because the optimization criteria is unpredictable due to subjective risk considerations that may be taken into account at any time. Although there is and additional level of costs for the trading of the private volume, it can be argued that competition will accelerate efficiency from an economic perspective. The amount of power put into the market will become less predictable, when the wind power spot market bid takes place on the basis of a risk consideration in addition to the forecast information itself. The scope of this project is to contribute to more efficient wind power integration targeted both to centralised and decentralised cost efficient IT solutions, which will complement each other in market based energy systems. The DEWEPS project resulted in an extension of the number of Ensemble forecasts, an incremental trade strategy for balancing unpredictable power production, and an IT platform for efficient handling of power generation units. Together, these three elements contribute to less need for reserves, more capacity in the market, and thus more competition. (LN)

  15. Solar-wind predictions for the Parker Solar Probe orbit. Near-Sun extrapolations derived from an empirical solar-wind model based on Helios and OMNI observations

    Science.gov (United States)

    Venzmer, M. S.; Bothmer, V.

    2018-03-01

    Context. The Parker Solar Probe (PSP; formerly Solar Probe Plus) mission will be humanitys first in situ exploration of the solar corona with closest perihelia at 9.86 solar radii (R⊙) distance to the Sun. It will help answer hitherto unresolved questions on the heating of the solar corona and the source and acceleration of the solar wind and solar energetic particles. The scope of this study is to model the solar-wind environment for PSPs unprecedented distances in its prime mission phase during the years 2018 to 2025. The study is performed within the Coronagraphic German And US SolarProbePlus Survey (CGAUSS) which is the German contribution to the PSP mission as part of the Wide-field Imager for Solar PRobe. Aim. We present an empirical solar-wind model for the inner heliosphere which is derived from OMNI and Helios data. The German-US space probes Helios 1 and Helios 2 flew in the 1970s and observed solar wind in the ecliptic within heliocentric distances of 0.29 au to 0.98 au. The OMNI database consists of multi-spacecraft intercalibrated in situ data obtained near 1 au over more than five solar cycles. The international sunspot number (SSN) and its predictions are used to derive dependencies of the major solar-wind parameters on solar activity and to forecast their properties for the PSP mission. Methods: The frequency distributions for the solar-wind key parameters, magnetic field strength, proton velocity, density, and temperature, are represented by lognormal functions. In addition, we consider the velocity distributions bi-componental shape, consisting of a slower and a faster part. Functional relations to solar activity are compiled with use of the OMNI data by correlating and fitting the frequency distributions with the SSN. Further, based on the combined data set from both Helios probes, the parameters frequency distributions are fitted with respect to solar distance to obtain power law dependencies. Thus an empirical solar-wind model for the inner

  16. A simplified model predicting the weight of the load carrying beam in a wind turbine blade

    DEFF Research Database (Denmark)

    Mikkelsen, Lars Pilgaard

    2016-01-01

    from 20 to 90 m. In addition, it can be seen that for a blade using glass fibre reinforced polymers, the design is controlled by the deflection and thereby the material stiffness in order to avoid the blade to hit the tower. On the other hand if using aluminium, the design will be controlled...... to predict the weight of the load carrying beam when using glassfibre reinforced polymers, carbon fibre reinforced polymers or an aluminium alloy as the construction material. Thereby, it is found that the weight of a glass fibre wind turbine blade is increased from 0.5 to 33 tons when the blade length grows...... by the fatigue resistance in orderto making the material survive the 100 to 500 million load cycles experience of the windturbine blade throughout the lifetime. The aluminium blade is also found to be considerably heavier compared with the composite blades....

  17. Prediction of Aerodynamic Coefficients for Wind Tunnel Data using a Genetic Algorithm Optimized Neural Network

    Science.gov (United States)

    Rajkumar, T.; Aragon, Cecilia; Bardina, Jorge; Britten, Roy

    2002-01-01

    A fast, reliable way of predicting aerodynamic coefficients is produced using a neural network optimized by a genetic algorithm. Basic aerodynamic coefficients (e.g. lift, drag, pitching moment) are modelled as functions of angle of attack and Mach number. The neural network is first trained on a relatively rich set of data from wind tunnel tests of numerical simulations to learn an overall model. Most of the aerodynamic parameters can be well-fitted using polynomial functions. A new set of data, which can be relatively sparse, is then supplied to the network to produce a new model consistent with the previous model and the new data. Because the new model interpolates realistically between the sparse test data points, it is suitable for use in piloted simulations. The genetic algorithm is used to choose a neural network architecture to give best results, avoiding over-and under-fitting of the test data.

  18. State-Space Modeling and Performance Analysis of Variable-Speed Wind Turbine Based on a Model Predictive Control Approach

    Directory of Open Access Journals (Sweden)

    H. Bassi

    2017-04-01

    Full Text Available Advancements in wind energy technologies have led wind turbines from fixed speed to variable speed operation. This paper introduces an innovative version of a variable-speed wind turbine based on a model predictive control (MPC approach. The proposed approach provides maximum power point tracking (MPPT, whose main objective is to capture the maximum wind energy in spite of the variable nature of the wind’s speed. The proposed MPC approach also reduces the constraints of the two main functional parts of the wind turbine: the full load and partial load segments. The pitch angle for full load and the rotating force for the partial load have been fixed concurrently in order to balance power generation as well as to reduce the operations of the pitch angle. A mathematical analysis of the proposed system using state-space approach is introduced. The simulation results using MATLAB/SIMULINK show that the performance of the wind turbine with the MPC approach is improved compared to the traditional PID controller in both low and high wind speeds.

  19. Method to predict fatigue lifetimes of GRP wind turbine blades and comparison with experiments

    Energy Technology Data Exchange (ETDEWEB)

    Echtermeyer, A.T. [Det Norske Veritas Research AS, Hoevik (Norway); Kensche, C. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Stuttgart (Germany, F.R); Bach, P. [Netherlands Energy Research Foundation (ECN), Petten (Netherlands); Poppen, M. [Aeronautical Research Inst. of Sweden, Bromma (Sweden); Lilholt, H.; Andersen, S.I.; Broendsted, P. [Risoe National Lab., Roskilde (Denmark)

    1996-12-01

    This paper describes a method to predict fatigue lifetimes of fiber reinforced plastics in wind turbine blades. It is based on extensive testing within the EU-Joule program. The method takes the measured fatigue properties of a material into account so that credit can be given to materials with improved fatigue properties. The large number of test results should also give confidence in the fatigue calculation method for fiber reinforced plastics. The method uses the Palmgren-Miner sum to predict lifetimes and is verified by tests using well defined load sequences. Even though this approach is generally well known in fatigue analysis, many details in the interpretation and extrapolation of the measurements need to be clearly defined, since they can influence the results considerably. The following subjects will be described: Method to measure SN curves and to obtain tolerance bounds, development of a constant lifetime diagram, evaluation of the load sequence, use of Palmgren-Miner sum, requirements for load sequence testing. The fatigue lifetime calculation method has been compared against measured data for simple loading sequences and the more complex WISPERX loading sequence for blade roots. The comparison is based on predicted mean lifetimes, using the same materials to obtain the basic SN curves and to measure laminates under complicated loading sequences. 24 refs, 7 figs, 5 tabs

  20. Modeling the fluid/soil interface erosion in the Hole Erosion Test

    Directory of Open Access Journals (Sweden)

    Kissi B.

    2012-07-01

    Full Text Available Soil erosion is a complex phenomenon which yields at its final stage to insidious fluid leakages under the hydraulic infrastructures known as piping and which are the main cause of their rupture. The Hole Erosion Test is commonly used to quantify the rate of piping erosion. In this work, The Hole Erosion Test is modelled by using Fluent software package. The aim is to predict the erosion rate of soil during the hole erosion test. The renormalization group theory – based k–ε turbulence model equations are used. This modelling makes it possible describing the effect of the clay concentration in flowing water on erosion. Unlike the usual one dimensional models, the proposed modelling shows that erosion is not uniform erosion along the hole length. In particular, the concentration of clay is found to increase noticeably the erosion rate.

  1. Predicting wind-induced vibrations of high-rise buildings using unsteady CFD and modal analysis

    KAUST Repository

    Zhang, Yue; Habashi, Wagdi G (Ed); Khurram, Rooh Ul Amin

    2015-01-01

    This paper investigates the wind-induced vibration of the CAARC standard tall building model, via unsteady Computational Fluid Dynamics (CFD) and a structural modal analysis. In this numerical procedure, the natural unsteady wind in the atmospheric

  2. Predicting the aerodynamic characteristics of 2D airfoil and the performance of 3D wind turbine using a CFD code

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Bum Suk; Kim, Mann Eung [Korean Register of Shipping, Daejeon (Korea, Republic of); Lee, Young Ho [Korea Maritime Univ., Busan (Korea, Republic of)

    2008-07-15

    Despite of the laminar-turbulent transition region co-exist with fully turbulence region around the leading edge of an airfoil, still lots of researchers apply to fully turbulence models to predict aerodynamic characteristics. It is well known that fully turbulent model such as standard k-model couldn't predict the complex stall and the separation behavior on an airfoil accurately, it usually leads to over prediction of the aerodynamic characteristics such as lift and drag forces. So, we apply correlation based transition model to predict aerodynamic performance of the NREL (National Renewable Energy Laboratory) Phase IV wind turbine. And also, compare the computed results from transition model with experimental measurement and fully turbulence results. Results are presented for a range of wind speed, for a NREL Phase IV wind turbine rotor. Low speed shaft torque, power, root bending moment, aerodynamic coefficients of 2D airfoil and several flow field figures results included in this study. As a result, the low speed shaft torque predicted by transitional turbulence model is very good agree with the experimental measurement in whole operating conditions but fully turbulent model(K- {epsilon}) over predict the shaft torque after 7m/s. Root bending moment is also good agreement between the prediction and experiments for most of the operating conditions, especially with the transition model.

  3. Predicting the aerodynamic characteristics of 2D airfoil and the performance of 3D wind turbine using a CFD code

    International Nuclear Information System (INIS)

    Kim, Bum Suk; Kim, Mann Eung; Lee, Young Ho

    2008-01-01

    Despite of the laminar-turbulent transition region co-exist with fully turbulence region around the leading edge of an airfoil, still lots of researchers apply to fully turbulence models to predict aerodynamic characteristics. It is well known that fully turbulent model such as standard k-model couldn't predict the complex stall and the separation behavior on an airfoil accurately, it usually leads to over prediction of the aerodynamic characteristics such as lift and drag forces. So, we apply correlation based transition model to predict aerodynamic performance of the NREL (National Renewable Energy Laboratory) Phase IV wind turbine. And also, compare the computed results from transition model with experimental measurement and fully turbulence results. Results are presented for a range of wind speed, for a NREL Phase IV wind turbine rotor. Low speed shaft torque, power, root bending moment, aerodynamic coefficients of 2D airfoil and several flow field figures results included in this study. As a result, the low speed shaft torque predicted by transitional turbulence model is very good agree with the experimental measurement in whole operating conditions but fully turbulent model(K- ε) over predict the shaft torque after 7m/s. Root bending moment is also good agreement between the prediction and experiments for most of the operating conditions, especially with the transition model

  4. A Collision Risk Model to Predict Avian Fatalities at Wind Facilities: An Example Using Golden Eagles, Aquila chrysaetos.

    Science.gov (United States)

    New, Leslie; Bjerre, Emily; Millsap, Brian; Otto, Mark C; Runge, Michael C

    2015-01-01

    Wind power is a major candidate in the search for clean, renewable energy. Beyond the technical and economic challenges of wind energy development are environmental issues that may restrict its growth. Avian fatalities due to collisions with rotating turbine blades are a leading concern and there is considerable uncertainty surrounding avian collision risk at wind facilities. This uncertainty is not reflected in many models currently used to predict the avian fatalities that would result from proposed wind developments. We introduce a method to predict fatalities at wind facilities, based on pre-construction monitoring. Our method can directly incorporate uncertainty into the estimates of avian fatalities and can be updated if information on the true number of fatalities becomes available from post-construction carcass monitoring. Our model considers only three parameters: hazardous footprint, bird exposure to turbines and collision probability. By using a Bayesian analytical framework we account for uncertainties in these values, which are then reflected in our predictions and can be reduced through subsequent data collection. The simplicity of our approach makes it accessible to ecologists concerned with the impact of wind development, as well as to managers, policy makers and industry interested in its implementation in real-world decision contexts. We demonstrate the utility of our method by predicting golden eagle (Aquila chrysaetos) fatalities at a wind installation in the United States. Using pre-construction data, we predicted 7.48 eagle fatalities year-1 (95% CI: (1.1, 19.81)). The U.S. Fish and Wildlife Service uses the 80th quantile (11.0 eagle fatalities year-1) in their permitting process to ensure there is only a 20% chance a wind facility exceeds the authorized fatalities. Once data were available from two-years of post-construction monitoring, we updated the fatality estimate to 4.8 eagle fatalities year-1 (95% CI: (1.76, 9.4); 80th quantile, 6

  5. Application of the nonlinear time series prediction method of genetic algorithm for forecasting surface wind of point station in the South China Sea with scatterometer observations

    International Nuclear Information System (INIS)

    Zhong Jian; Dong Gang; Sun Yimei; Zhang Zhaoyang; Wu Yuqin

    2016-01-01

    The present work reports the development of nonlinear time series prediction method of genetic algorithm (GA) with singular spectrum analysis (SSA) for forecasting the surface wind of a point station in the South China Sea (SCS) with scatterometer observations. Before the nonlinear technique GA is used for forecasting the time series of surface wind, the SSA is applied to reduce the noise. The surface wind speed and surface wind components from scatterometer observations at three locations in the SCS have been used to develop and test the technique. The predictions have been compared with persistence forecasts in terms of root mean square error. The predicted surface wind with GA and SSA made up to four days (longer for some point station) in advance have been found to be significantly superior to those made by persistence model. This method can serve as a cost-effective alternate prediction technique for forecasting surface wind of a point station in the SCS basin. (paper)

  6. The state-of-the-art in short-term prediction of wind power. A literature overview

    Energy Technology Data Exchange (ETDEWEB)

    Giebel, G.; Brownsword, R.; Kariniotakis, G.

    2003-08-01

    Based on an appropriate questionnaire (WP1.1) and some other works already in progress, this report details the state-of-the-art in short term prediction of wind power, mostly summarising nearly all existing literature on the topic. (au)

  7. Prediction of tropical cyclone over North Indian Ocean using WRF model: sensitivity to scatterometer winds, ATOVS and ATMS radiances

    KAUST Repository

    Dodla, Venkata B.; Srinivas, Desamsetti; Dasari, Hari Prasad; Gubbala, Chinna Satyanarayana

    2016-01-01

    prediction with least errors less than 100 km up to 60 hours and producing pre-deepening and deepening periods accurately. The Control and SCAT wind assimilation experiments have shown good track but the errors were 150-200 km and gradual deepening from

  8. Prediction of geomagnetic storms from solar wind data with the use of a neural network

    Directory of Open Access Journals (Sweden)

    H. Lundstedt

    Full Text Available An artificial feed-forward neural network with one hidden layer and error back-propagation learning is used to predict the geomagnetic activity index (Dst one hour in advance. The Bz-component and ΣBz, the density, and the velocity of the solar wind are used as input to the network. The network is trained on data covering a total of 8700 h, extracted from the 25-year period from 1963 to 1987, taken from the NSSDC data base. The performance of the network is examined with test data, not included in the training set, which covers 386 h and includes four different storms. Whilst the network predicts the initial and main phase well, the recovery phase is not modelled correctly, implying that a single hidden layer error back-propagation network is not enough, if the measured Dst is not available instantaneously. The performance of the network is independent of whether the raw parameters are used, or the electric field and square root of the dynamical pressure.

  9. A review on the young history of the wind power short-term prediction

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Alexandre; Navarro, Jorge [Wind Energy, Division of Renewable Energies, Department of Energy, CIEMAT, Av. Complutense, 22, Ed. 42, 28044 Madrid (Spain); Crespo, Antonio [Laboratorio de Mecanica de Fluidos, Departmento de Ingenieria Energetica y Fluidomecanica, ETSII, Universidad Politecnica de Madrid, C/Jose Gutierrez Abascal, 2-28006 Madrid (Spain); Lizcano, Gil [Oxford University Centre for the Environment, University of Oxford, South Parks Road, Oxford OX1 3QY (United Kingdom); Madsen, Henrik [Informatics and Mathematical Modelling - IMM, Technical University of Denmark, Richard Petersens Plads, Building 321, Office 019, 2800 Kgs. Lyngby (Denmark); Feitosa, Everaldo [Brazilian Wind Energy Centre - CBEE, Centro de Tecnologia e Geociencias, UFPE-50.740-530 Recife, PE (Brazil)

    2008-08-15

    This paper makes a brief review on 30 years of history of the wind power short-term prediction, since the first ideas and sketches on the theme to the actual state of the art on models and tools, giving emphasis to the most significant proposals and developments. The two principal lines of thought on short-term prediction (mathematical and physical) are indistinctly treated here and comparisons between models and tools are avoided, mainly because, on the one hand, a standard for a measure of performance is still not adopted and, on the other hand, it is very important that the data are exactly the same in order to compare two models (this fact makes it almost impossible to carry out a quantitative comparison between a huge number of models and methods). In place of a quantitative description, a qualitative approach is preferred for this review, remarking the contribution (and innovative aspect) of each model. On the basis of the review, some topics for future research are pointed out. (author)

  10. Model predictive control of trailing edge flaps on a wind turbine blade

    DEFF Research Database (Denmark)

    Castaignet, Damien Bruno

    of the wind turbine fatigue and extreme loads. This potential was confirmed with wind tunnel tests made on blade sections with trailing edge flaps and on a scaled two-bladed wind turbine in a wind tunnel. The work presented in this thesis includes a full-scale test run on a Vestas V27 wind turbine equipped...... fatigue loads by 23%, but also the main shaft and the tower fatigue loads by up to 32%. Extreme loads during normal production also benefit from the trailing edge flaps. At last, the same controller was run on the Vestas V27 wind turbine located at the Risø Campus of the Technical University of Denmark......Trailing edge flaps on wind turbine blades have been investigated for several years. Aero-servoelastic simulations carried out with different simulation tools, trailing edge flaps configurations and controller designs proved that trailing edge flaps are a suitable solution for reducing some...

  11. Erhversbetinget erosion?

    DEFF Research Database (Denmark)

    Dige, Irene; Gjørup, Hans; Nyvad, Bente

    2012-01-01

    Baggrund – I forbindelse med dental erosion er en grundig udredning af patienten vigtig, således at årsagen til erosionernes opståen findes, og der kan iværksættes adækvat forebyggende indsats. En sådan udredning er ikke mindst vigtig, når arbejdsmiljøet mistænkes. Patienttilfælde – En 30-årig...... arbejdsskade, men ikke anerkendt, da erosioner ikke er optaget på Arbejdsskadestyrelsens liste over erhvervssygdomme. En systematisk registrering af lignende tilfælde kunne imidlertid på sigt ændre retspraksis for fremtidige patienter med arbejdsbetinget erosion....... patient, der arbejder som pladesmed, blev henvist til Landsdels- og Videnscenter, Århus Sygehus, med henblik på udredning af patientens kraftige slid. Patienten udviste ikke-alderssvarende tandslid af emalje og dentin svarende til erosion forårsaget af syredampe i arbejdsmiljøet, muligvis forstærket af...

  12. Impact assessment of rainfall-vegetation on sedimentation and predicting erosion-prone region by GIS and RS

    Directory of Open Access Journals (Sweden)

    Mahboob Alam

    2016-03-01

    Full Text Available Water reservoirs are facing universal sedimentation problems worldwide. Land covers, whether natural or manmade, eventually change, and the vegetation cover and rainfall have a great effect on the sediment load. Traditional techniques for analysing this problem are time-consuming and spatially limited. Remote sensing (RS provides a convenient way to observe land cover changes, and geographic information system (GIS provides tools for geographic analysis. This study demonstrates a GIS-based methodology for calculating the impact of vegetation and rainfall on the sediment load using remotely sensed data. Moderate resolution imaging spectroradiometer data were used to observe temporal changes in the vegetation-cover area of the watershed surface. The total drainage area for the reservoir was calculated from shuttle radar topographic mission data. The annual rainfall amount was used to compute the annual available rainwater for the watershed, and the impact of the annual available rainwater on the vegetation-covered area was determined. In addition, areas that were adding sedimentation to the reservoir were identified. An inverse relationship between the rainfall and vegetation cover was observed, clearly showing the triggering of erosion.

  13. Predictions of Resuspension of Highway Detention Pond Deposits in Interrain Event Periods due to Wind-Induced Currents and Waves

    DEFF Research Database (Denmark)

    Bentzen, Thomas Ruby; Larsen, Torben; Rasmussen, Michael R.

    2009-01-01

    -shear stress induced by the return flow near the bed and waves both generated by the wind. Wind statistics for 30 years have been applied for prediction of the annual discharged bulk of suspended solids and associated pollutants; fluoranthene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, dibenzo......(a,h)anthracene and indeno(1,2,3-cd)pyrene (PAHs) and the heavy metals of cadmium, chromium, copper, lead, nickel, and zinc. The current and wave-generated bed-shear stresses entail a discharged bulk of pollutants corresponding to approximately 10% of the annual accumulation of pollutants in the present pond due...

  14. Stochastic Model Predictive Fault Tolerant Control Based on Conditional Value at Risk for Wind Energy Conversion System

    Directory of Open Access Journals (Sweden)

    Yun-Tao Shi

    2018-01-01

    Full Text Available Wind energy has been drawing considerable attention in recent years. However, due to the random nature of wind and high failure rate of wind energy conversion systems (WECSs, how to implement fault-tolerant WECS control is becoming a significant issue. This paper addresses the fault-tolerant control problem of a WECS with a probable actuator fault. A new stochastic model predictive control (SMPC fault-tolerant controller with the Conditional Value at Risk (CVaR objective function is proposed in this paper. First, the Markov jump linear model is used to describe the WECS dynamics, which are affected by many stochastic factors, like the wind. The Markov jump linear model can precisely model the random WECS properties. Second, the scenario-based SMPC is used as the controller to address the control problem of the WECS. With this controller, all the possible realizations of the disturbance in prediction horizon are enumerated by scenario trees so that an uncertain SMPC problem can be transformed into a deterministic model predictive control (MPC problem. Finally, the CVaR object function is adopted to improve the fault-tolerant control performance of the SMPC controller. CVaR can provide a balance between the performance and random failure risks of the system. The Min-Max performance index is introduced to compare the fault-tolerant control performance with the proposed controller. The comparison results show that the proposed method has better fault-tolerant control performance.

  15. Modeling and control design of a stand alone wind energy conversion system based on functional model predictive control

    Energy Technology Data Exchange (ETDEWEB)

    Kassem, Ahmed M. [Beni-Suef University, Electrical Dept., Beni Suef (Egypt)

    2012-09-15

    This paper investigates the application of the model predictive control (MPC) approach to control the voltage and frequency of a stand alone wind generation system. This scheme consists of a wind turbine which drives an induction generator feeding an isolated load. A static VAR compensator is connected at the induction generator terminals to regulate the load voltage. The rotor speed, and thereby the load frequency are controlled via adjusting the mechanical power input using the blade pitch-angle. The MPC is used to calculate the optimal control actions including system constraints. To alleviate computational effort and to reduce numerical problems, particularly in large prediction horizon, an exponentially weighted functional model predictive control (FMPC) is employed. Digital simulations have been carried out in order to validate the effectiveness of the proposed scheme. The proposed controller has been tested through step changes in the wind speed and the load impedance. Simulation results show that adequate performance of the proposed wind energy scheme has been achieved. Moreover, this scheme is robust against the parameters variation and eliminates the influence of modeling and measurement errors. (orig.)

  16. User manual of Soil and Cesium Transport (SACT), a program to predict long-term Cs distribution using USLE for soil erosion, transportation and deposition

    International Nuclear Information System (INIS)

    Saito, Hiroshi; Yamaguchi, Masaaki; Kitamura, Akihiro

    2016-12-01

    This manual provides useful and necessary information to users of 'SACT' (Soil and Cesium Transport), which Japan Atomic Energy Agency (JAEA) has developed to predict a long-term distribution of Cs deposited on the land surface of Fukushima due to the Fukushima Daiichi Nuclear Power Station accident on March 11, 2011. SACT calculates soil movement (erosion, transportation and deposition) and resulting Cs migration, and predicts its future distribution, with the assumption that Cs is adhered to soil initially. SACT uses USLE (Universal Soil Loss Equation) for potential soil loss and simple hydraulic equations for soil transportation and deposition in which soil is divided into course-grained sand and fine-grained silt/clay. The amount of Cs moved with soil is predicted by the amount of above-mentioned soil movement and concentration ratio of Cs for each grain-size. SACT utilizes the 'ArcGIS' software and the GIS (Geographical Information System). SACT is characterized by its simplicity which enables fast calculation for wide area for long-term duration, using existing simple equations including USLE. Data for used parameters are widely available, and site-specific calculations are possible by using data obtained from the targeted area. (author)

  17. Power and loads for wind turbines in yawed conditions. Analysis of field measurements and aerodynamic predictions

    Energy Technology Data Exchange (ETDEWEB)

    Boorsma, K. [ECN Wind Energy, Petten (Netherlands)

    2012-11-15

    A description is given of the work carried out within the framework of the FLOW (Far and Large Offshore Wind) project on single turbine performance in yawed flow conditions. Hereto both field measurements as well as calculations with an aerodynamic code are analyzed. The rotors of horizontal axis wind turbines follow the changes in the wind direction for optimal performance. The reason is that the power is expected to decrease for badly oriented rotors. So, insight in the effects of the yaw angle on performance is important for optimization of the yaw control of each individual turbine. The effect of misalignment on performance and loads of a single 2.5 MW wind turbine during normal operation is investigated. Hereto measurements at the ECN Wind Turbine Test Site Wieringermeer (EWTW) are analyzed from December 2004 until April 2009. Also, the influence of yaw is studied using a design code and results from this design code are compared with wind tunnel measurements.

  18. Short-term wind speed prediction based on the wavelet transformation and Adaboost neural network

    Science.gov (United States)

    Hai, Zhou; Xiang, Zhu; Haijian, Shao; Ji, Wu

    2018-03-01

    The operation of the power grid will be affected inevitably with the increasing scale of wind farm due to the inherent randomness and uncertainty, so the accurate wind speed forecasting is critical for the stability of the grid operation. Typically, the traditional forecasting method does not take into account the frequency characteristics of wind speed, which cannot reflect the nature of the wind speed signal changes result from the low generality ability of the model structure. AdaBoost neural network in combination with the multi-resolution and multi-scale decomposition of wind speed is proposed to design the model structure in order to improve the forecasting accuracy and generality ability. The experimental evaluation using the data from a real wind farm in Jiangsu province is given to demonstrate the proposed strategy can improve the robust and accuracy of the forecasted variable.

  19. Predicting Atmospheric Ionization and Excitation by Precipitating SEP and Solar Wind Protons Measured By MAVEN

    Science.gov (United States)

    Jolitz, Rebecca; Dong, Chuanfei; Lee, Christina; Lillis, Rob; Brain, David; Curry, Shannon; Halekas, Jasper; Bougher, Stephen W.; Jakosky, Bruce

    2017-10-01

    Precipitating energetic particles ionize and excite planetary atmospheres, increasing electron content and producing aurora. At Mars, the solar wind and solar energetic particles (SEPs) can precipitate directly into the atmosphere because solar wind protons can charge exchange to become neutral and pass the magnetosheath, and SEPs are sufficiently energetic to cross the magnetosheath unchanged. We will compare ionization and Lyman alpha emission rates for solar wind and SEP protons during nominal solar activity and a CME shock front impact event on May 16 2016. We will use the Atmospheric Scattering of Protons and Energetic Neutrals (ASPEN) model to compare excitation and ionization rates by SEPs and solar wind protons currently measured by the SWIA (Solar Wind Ion Analyzer) and SEP instruments aboard the MAVEN spacecraft. Results will help quantify how SEP and solar wind protons influence atmospheric energy deposition during solar minimum.

  20. Improving Wind Predictions in the Marine Atmospheric Boundary Layer through Parameter Estimation in a Single-Column Model

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jared A.; Hacker, Joshua P.; Delle Monache, Luca; Kosović, Branko; Clifton, Andrew; Vandenberghe, Francois; Rodrigo, Javier Sanz

    2016-12-14

    A current barrier to greater deployment of offshore wind turbines is the poor quality of numerical weather prediction model wind and turbulence forecasts over open ocean. The bulk of development for atmospheric boundary layer (ABL) parameterization schemes has focused on land, partly due to a scarcity of observations over ocean. The 100-m FINO1 tower in the North Sea is one of the few sources worldwide of atmospheric profile observations from the sea surface to turbine hub height. These observations are crucial to developing a better understanding and modeling of physical processes in the marine ABL. In this study, we use the WRF single column model (SCM), coupled with an ensemble Kalman filter from the Data Assimilation Research Testbed (DART), to create 100-member ensembles at the FINO1 location. The goal of this study is to determine the extent to which model parameter estimation can improve offshore wind forecasts.

  1. Relative performance of different numerical weather prediction models for short term predition of wind wnergy

    Energy Technology Data Exchange (ETDEWEB)

    Giebel, G; Landberg, L [Risoe National Lab., Wind Energy and Atmospheric Physics Dept., Roskilde (Denmark); Moennich, K; Waldl, H P [Carl con Ossietzky Univ., Faculty of Physics, Dept. of Energy and Semiconductor, Oldenburg (Germany)

    1999-03-01

    In several approaches presented in other papers in this conference, short term forecasting of wind power for a time horizon covering the next two days is done on the basis of Numerical Weather Prediction (NWP) models. This paper explores the relative merits of HIRLAM, which is the model used by the Danish Meteorological Institute, the Deutschlandmodell from the German Weather Service and the Nested Grid Model used in the US. The performance comparison will be mainly done for a site in Germany which is in the forecasting area of both the Deutschlandmodell and HIRLAM. In addition, a comparison of measured data with the forecasts made for one site in Iowa will be included, which allows conclusions on the merits of all three models. Differences in the relative performances could be due to a better tailoring of one model to its country, or to a tighter grid, or could be a function of the distance between the grid points and the measuring site. Also the amount, in which the performance can be enhanced by the use of model output statistics (topic of other papers in this conference) could give insights into the performance of the models. (au)

  2. FY 1998 Report on development of large-scale wind power generation systems. Feasibility study on development of new technologies for wind power generation, and study on local wind resource prediction model; 1998 nendo ogata furyoku hatsuden system kaihatsu seika hokokusho. Furyoku hatsuden shingijutsu kaihatsu kanosei chosa (kyokusho fukyo yosoku shuho ni kansuru chosa)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-03-01

    Described herein are the FY 1998 results of the study on local wind resource prediction model. The local wind resource prediction models developed so far apply the solutions based on the existing linear models (WASP and AVENU) for relatively flat terrain. These models are studied for their applicability limits. The study covers wind direction and speed patterns of the surface wind and upper winds at 3 sites in Hokkaido, Fukushima Pref. and Shizuoka Pref. The surface winds are found to be correlated with the upper winds both for wind direction and wind speed in almost all cases. Next, wind resources simulations are carried out for each of the classified weather patterns using the existing models, and the prediction errors are studied. The results show that the prediction accuracy of the existing linear models is highly dependent on inputs of observed data, and that the accuracy tends to decrease for the situations where the upper and surface wind conditions greatly differ from each other, as in the case of a land and sea breeze of thermal origin. It is also confirmed that prediction accuracy is lower on complex terrain than on flat terrain. (NEDO)

  3. Optimal Real-Time Scheduling for Hybrid Energy Storage Systems and Wind Farms Based on Model Predictive Control

    Directory of Open Access Journals (Sweden)

    Meng Xiong

    2015-08-01

    Full Text Available Energy storage devices are expected to be more frequently implemented in wind farms in near future. In this paper, both pumped hydro and fly wheel storage systems are used to assist a wind farm to smooth the power fluctuations. Due to the significant difference in the response speeds of the two storages types, the wind farm coordination with two types of energy storage is a problem. This paper presents two methods for the coordination problem: a two-level hierarchical model predictive control (MPC method and a single-level MPC method. In the single-level MPC method, only one MPC controller coordinates the wind farm and the two storage systems to follow the grid scheduling. Alternatively, in the two-level MPC method, two MPC controllers are used to coordinate the wind farm and the two storage systems. The structure of two level MPC consists of outer level and inner level MPC. They run alternatively to perform real-time scheduling and then stop, thus obtaining long-term scheduling results and sending some results to the inner level as input. The single-level MPC method performs both long- and short-term scheduling tasks in each interval. The simulation results show that the methods proposed can improve the utilization of wind power and reduce wind power spillage. In addition, the single-level MPC and the two-level MPC are not interchangeable. The single-level MPC has the advantage of following the grid schedule while the two-level MPC can reduce the optimization time by 60%.

  4. Erodibility of waste (Loess) soils from construction sites under water and wind erosional forces.

    Science.gov (United States)

    Tanner, Smadar; Katra, Itzhak; Argaman, Eli; Ben-Hur, Meni

    2018-03-01

    Excess soils from construction sites (waste soils) become a problem when exposed to soil erosion by water or wind. Understanding waste soil erodibility can contribute to its proper reuse for various surface applications. The general objective of the study was to provide a better understanding of the effects of soil properties on erodibility of waste soils excavated from various depths in a semiarid region under rainfall and wind erosive forces. Soil samples excavated from the topsoil (0-0.3m) and subsoil layers (0.3-0.9 and >1m depths) were subjected to simulated rainfall and wind. Under rainfall erosive forces, the subsoils were more erodible than the topsoil, in contrast to the results obtained under wind erosive forces. Exchangeable sodium percentage was the main factor controlling soil erodibility (K i ) under rainfall, and a significant logarithmic regression line was found between these two parameters. In addition, a significant, linear regression was found between K i and slaking values for the studied soil samples, suggesting that the former can be predicted from the latter. Soil erodibility under wind erosion force was controlled mainly by the dry aggregate characteristics (mean weight diameter and aggregate density): their higher values in the subsoil layers resulted in lower soil erodibility compared to the topsoil. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Aerodynamic noise prediction of a Horizontal Axis Wind Turbine using Improved Delayed Detached Eddy Simulation and acoustic analogy

    International Nuclear Information System (INIS)

    Ghasemian, Masoud; Nejat, Amir

    2015-01-01

    Highlights: • The noise predictions are performed by Ffowcs Williams and Hawkings method. • There is a direct relation between the radiated noise and the wind speed. • The tonal peaks in the sound spectra match with the blade passing frequency. • The quadrupole noises have negligible effect on the low frequency noises. - Abstract: This paper presents the results of the aerodynamic and aero-acoustic prediction of the flow field around the National Renewable Energy Laboratory Phase VI wind turbine. The Improved Delayed Detached Eddy Simulation turbulence model is applied to obtain the instantaneous turbulent flow field. The noise prediction is carried out using the Ffowcs Williams and Hawkings acoustic analogy. Simulations are performed for three different inflow conditions, U = 7, 10, 15 m/s. The capability of the Improved Delayed Detached Eddy Simulation turbulence model in massive separation is verified with available experimental data for pressure coefficient. The broadband noises of the turbulent boundary layers and the tonal noises due to the blade passing frequency are predicted via flow field noise simulation. The contribution of the thickness, loading and quadrupole noises are investigated, separately. The results indicated that there is a direct relation between the strength of the radiated noise and the wind speed. Furthermore, the effect of the receiver location on the Overall Sound Pressure Level is investigated

  6. Very short-term spatio-temporal wind power prediction using a censored Gaussian field

    DEFF Research Database (Denmark)

    Baxevani, Anastassia; Lenzi, Amanda

    2018-01-01

    Wind power is a renewable energy resource, that has relatively cheap installation costs and it is highly possible that will become the main energy resource in the near future. Wind power needs to be integrated efficiently into electricity grids, and to optimize the power dispatch, techniques...

  7. Energy Yield Prediction of Offshore Wind Farm Clusters at the EERA-DTOC European Project

    DEFF Research Database (Denmark)

    Cantero, E.; Hasager, Charlotte Bay; Réthoré, Pierre-Elouan

    2014-01-01

    third-party models. Wake models have been benchmarked on the Horns Rev and, currently, on the Lilgrund wind farm test cases. Dedicated experiments from ‘BARD Offshore 1’ wind farm will using scanning lidars will produce new data for the validation of wake models. Furthermore, the project includes power...

  8. Energy yield prediction of offshore wind farm clusters at the EERA-DTOC European project

    DEFF Research Database (Denmark)

    Cantero, E.; Sanz, J.; Lorenzo, S.

    2013-01-01

    third-party models. Wake models have been benchmarked on the Horns Rev and, currently, on the Lilgrund wind farm test cases. Dedicated experiments from ‘BARD Offshore 1’ wind farm will using scanning lidars will produce new data for the validation of wake models. Furthermore, the project includes power...

  9. The Major Cause of Observed Erosion Surge on the Beaches North ...

    African Journals Online (AJOL)

    Surges in coastal erosion north of Dar es Salaam city have been documented from 1977 to the early 1980s and around 1997/98. Analysis of the wind data shows that the documented increase in coastal erosion coincided with increased wind speeds. Extreme winds in excess of 10-11 m s-1 were experienced during ...

  10. Method to Predict Long Time Span of Scour Around Offshore Wind Turbine Foundations

    DEFF Research Database (Denmark)

    Dixen, Martin; Lohmann, Iris P.; Christensen, Erik Damgaard

    2012-01-01

    tables have been made based on full 3D numerical simulations of the flow and sediment transport for fixed configurations of the scour hole. When changing the governing parameters which are causing the scour development around the structure, the erosion rate or backfilling rate can be calculated from...

  11. Remotely sensed wind speed predicts soaring behaviour in a wide-ranging pelagic seabird.

    Science.gov (United States)

    Gibb, Rory; Shoji, Akiko; Fayet, Annette L; Perrins, Chris M; Guilford, Tim; Freeman, Robin

    2017-07-01

    Global wind patterns affect flight strategies in many birds, including pelagic seabirds, many of which use wind-powered soaring to reduce energy costs during at-sea foraging trips and migration. Such long-distance movement patterns are underpinned by local interactions between wind conditions and flight behaviour, but these fine-scale relationships are far less well understood. Here we show that remotely sensed ocean wind speed and direction are highly significant predictors of soaring behaviour in a migratory pelagic seabird, the Manx shearwater ( Puffinus puffinus ). We used high-frequency GPS tracking data (10 Hz) and statistical behaviour state classification to identify two energetic modes in at-sea flight, corresponding to flap-like and soar-like flight. We show that soaring is significantly more likely to occur in tailwinds and crosswinds above a wind speed threshold of around 8 m s -1 , suggesting that these conditions enable birds to reduce metabolic costs by preferentially soaring over flapping. Our results suggest a behavioural mechanism by which wind conditions may shape foraging and migration ecology in pelagic seabirds, and thus indicate that shifts in wind patterns driven by climate change could impact this and other species. They also emphasize the emerging potential of high-frequency GPS biologgers to provide detailed quantitative insights into fine-scale flight behaviour in free-living animals. © 2017 The Author(s).

  12. Aero-acoustics prediction of a vertical axis wind turbine using Large Eddy Simulation and acoustic analogy

    International Nuclear Information System (INIS)

    Ghasemian, Masoud; Nejat, Amir

    2015-01-01

    Operating wind turbines generate tonal and broadband noises affecting the living environment adversely; especially small wind turbines located in the vicinity of human living places. Therefore, it is important to determine the level of noise pollution of such type of wind turbine installation. The current study carries out numerical prediction for aerodynamic noise radiated from an H-Darrieus Vertical Axis Wind Turbine. Incompressible LES (Large Eddy Simulation) is conducted to obtain the instantaneous turbulent flow field. The noise predictions are performed by the Ffowcs Williams and Hawkings (FW–H) acoustic analogy formulation. Simulations are performed for five different tip-speed ratios. First, the mean torque coefficient is compared with the experimental data, and good agreement is observed. Then, the research focuses on the broadband noises of the turbulent boundary layers and the tonal noises due to blade passing frequency. The contribution of the thickness, loading and quadrupole noises are investigated, separately. The results indicate a direct relation between the strength of the radiated noise and the rotational speed. Furthermore, the effect of receiver distance on the OASPL (Overall Sound Pressure Level) is investigated. It is concluded that the OASPL varies with a logarithmic trend with the receiver distance as it was expected. - Highlights: • Large Eddy Simulation has been used to predict the turbulent flow field. • The Ffowcs Williams and Hawkings method was employed to predict radiated noise. • There is a direct relation between the radiated noise and the tip speed ratio. • The quadrupole noises have negligible effect on the tonal noises

  13. The Gale Crater Mound in a Regional Geologic Setting: Comparison Study of Wind Erosion in Gale Crater and Within a 1000 KM Radius

    Science.gov (United States)

    Dapremont. A.; Allen, C.; Runyon, C.

    2014-01-01

    Gale is a Late Noachian/Early Hesperian impact crater located on the dichotomy boundary separating the southern highlands and the northern lowlands of Mars. NASA's Curiosity Rover is currently exploring Gale, searching for evidence of habitability early in Mars history. With an approximate diameter of 155 km, and a approx. 5 km central mound informally titled Mt. Sharp, Gale represents a region of geologic interest due to the abundance of knowledge that can be derived, through its sedimentary deposits, pertaining to the environmental evolution of Mars. This study was undertaken to compare wind erosional features in Gale Crater and within sediments in a 1000 km radial area. The ultimate objective of this comparison was to determine if or how Gale relates to the surrounding region.

  14. The new generation of tools for prediction of wind power potential and site selection

    DEFF Research Database (Denmark)

    Lundtang Petersen, Erik

    2012-01-01

    , from insufficient input data to deficient physics and resolution in any of the models, model linking issues, insufficient resolution or errors in surface topographical data such as terrain heights, land cover data etc. Therefore it has been decided on a European Union level to launch a project “The New...... European Wind Atlas” aiming at reducing overall uncertainties in determining wind conditions; standing on three legs: A data bank from a series of intensive measuring campaigns; a thorough examination and redesign of the model chain from global, mesoscale to microscale models and the creation of the wind...

  15. Fluctuations and predictability of wind and hydropower. Deliverable 2.1

    DEFF Research Database (Denmark)

    Giebel, Gregor; Holttinen, H.; Söder, L.

    2004-01-01

    The report forms the deliverable D2.1 of the EU supported project Wind Power Integration in a Liberalised Electricity Market (WILMAR). The handling and generation of the necessary wind and hydro time series for the project’s power system planningsimulation model is described. The wind power...... and the hydro power time series on hourly basis are generated on basis of real data for all the geographical regions included in the analysis in order to realistically represent the various correlations intime and displacement. Models have been developed to generate various realistic future time series based...

  16. Process-based coastal erosion modeling for Drew Point (North Slope, Alaska)

    Science.gov (United States)

    Ravens, Thomas M.; Jones, Benjamin M.; Zhang, Jinlin; Arp, Christopher D.; Schmutz, Joel A.

    2012-01-01

    A predictive, coastal erosion/shoreline change model has been developed for a small coastal segment near Drew Point, Beaufort Sea, Alaska. This coastal setting has experienced a dramatic increase in erosion since the early 2000’s. The bluffs at this site are 3-4 m tall and consist of ice-wedge bounded blocks of fine-grained sediments cemented by ice-rich permafrost and capped with a thin organic layer. The bluffs are typically fronted by a narrow (∼ 5  m wide) beach or none at all. During a storm surge, the sea contacts the base of the bluff and a niche is formed through thermal and mechanical erosion. The niche grows both vertically and laterally and eventually undermines the bluff, leading to block failure or collapse. The fallen block is then eroded both thermally and mechanically by waves and currents, which must occur before a new niche forming episode may begin. The erosion model explicitly accounts for and integrates a number of these processes including: (1) storm surge generation resulting from wind and atmospheric forcing, (2) erosional niche growth resulting from wave-induced turbulent heat transfer and sediment transport (using the Kobayashi niche erosion model), and (3) thermal and mechanical erosion of the fallen block. The model was calibrated with historic shoreline change data for one time period (1979-2002), and validated with a later time period (2002-2007).

  17. The use of real-time off-site observations as a methodology for increasing forecast skill in prediction of large wind power ramps one or more hours ahead of their impact on a wind plant.

    Energy Technology Data Exchange (ETDEWEB)

    Martin Wilde, Principal Investigator

    2012-12-31

    ABSTRACT Application of Real-Time Offsite Measurements in Improved Short-Term Wind Ramp Prediction Skill Improved forecasting performance immediately preceding wind ramp events is of preeminent concern to most wind energy companies, system operators, and balancing authorities. The value of near real-time hub height-level wind data and more general meteorological measurements to short-term wind power forecasting is well understood. For some sites, access to onsite measured wind data - even historical - can reduce forecast error in the short-range to medium-range horizons by as much as 50%. Unfortunately, valuable free-stream wind measurements at tall tower are not typically available at most wind plants, thereby forcing wind forecasters to rely upon wind measurements below hub height and/or turbine nacelle anemometry. Free-stream measurements can be appropriately scaled to hub-height levels, using existing empirically-derived relationships that account for surface roughness and turbulence. But there is large uncertainty in these relationships for a given time of day and state of the boundary layer. Alternatively, forecasts can rely entirely on turbine anemometry measurements, though such measurements are themselves subject to wake effects that are not stationary. The void in free-stream hub-height level measurements of wind can be filled by remote sensing (e.g., sodar, lidar, and radar). However, the expense of such equipment may not be sustainable. There is a growing market for traditional anemometry on tall tower networks, maintained by third parties to the forecasting process (i.e., independent of forecasters and the forecast users). This study examines the value of offsite tall-tower data from the WINDataNOW Technology network for short-horizon wind power predictions at a wind farm in northern Montana. The presentation shall describe successful physical and statistical techniques for its application and the practicality of its application in an operational

  18. A mathematical model of reservoir sediment quality prediction based on land-use and erosion processes in watershed

    Science.gov (United States)

    Junakova, N.; Balintova, M.; Junak, J.

    2017-10-01

    The aim of this paper is to propose a mathematical model for determining of total nitrogen (N) and phosphorus (P) content in eroded soil particles with emphasis on prediction of bottom sediment quality in reservoirs. The adsorbed nutrient concentrations are calculated using the Universal Soil Loss Equation (USLE) extended by the determination of the average soil nutrient concentration in top soils. The average annual vegetation and management factor is divided into five periods of the cropping cycle. For selected plants, the average plant nutrient uptake divided into five cropping periods is also proposed. The average nutrient concentrations in eroded soil particles in adsorbed form are modified by sediment enrichment ratio to obtain the total nutrient content in transported soil particles. The model was designed for the conditions of north-eastern Slovakia. The study was carried out in the agricultural basin of the small water reservoir Klusov.

  19. A Diagnostic and Predictive Framework for Wind Turbine Drive Train Monitoring

    DEFF Research Database (Denmark)

    Bach-Andersen, Martin

    Vast amount of data are collected minute by minute from wind turbines around the world. This thesis represents a focused research effort into discovering new ways of processing these data streams in order to gain insights which can be used to lower the maintenance costs of wind turbines and increase......, early fault identification based on analysis of complex vibration patterns which is a domain previously reserved for human experts, is shown to be solved with high accuracy using deep learning architecture strained in a fully supervised sense from the data collected in a large scale wind turbine...... monitoring platform. The research shows a way towards a fully automatized data-driven wind turbine diagnostic processing system that is highly scalable and requires little or no feature engineering and system modeling....

  20. Prediction of tropical cyclone over North Indian Ocean using WRF model: sensitivity to scatterometer winds, ATOVS and ATMS radiances

    KAUST Repository

    Dodla, Venkata B.

    2016-05-03

    Tropical cyclone prediction, in terms of intensification and movement, is important for disaster management and mitigation. Hitherto, research studies were focused on this issue that lead to improvement in numerical models, initial data with data assimilation, physical parameterizations and application of ensemble prediction. Weather Research and Forecasting (WRF) model is the state-of-art model for cyclone prediction. In the present study, prediction of tropical cyclone (Phailin, 2013) that formed in the North Indian Ocean (NIO) with and without data assimilation using WRF model has been made to assess impacts of data assimilation. WRF model was designed to have nested two domains of 15 and 5 km resolutions. In the present study, numerical experiments are made without and with the assimilation of scatterometer winds, and radiances from ATOVS and ATMS. The model performance was assessed in respect to the movement and intensification of cyclone. ATOVS data assimilation experiment had produced the best prediction with least errors less than 100 km up to 60 hours and producing pre-deepening and deepening periods accurately. The Control and SCAT wind assimilation experiments have shown good track but the errors were 150-200 km and gradual deepening from the beginning itself instead of sudden deepening.