WorldWideScience

Sample records for prevailing wind direction

  1. Seasonal prevailing surface winds in Northern Serbia

    Science.gov (United States)

    Tošić, Ivana; Gavrilov, Milivoj B.; Marković, Slobodan B.; Ruman, Albert; Putniković, Suzana

    2018-02-01

    Seasonal prevailing surface winds are analyzed in the territory of Northern Serbia, using observational data from 12 meteorological stations over several decades. In accordance with the general definition of prevailing wind, two special definitions of this term are used. The seasonal wind roses in 16 directions at each station are analyzed. This study shows that the prevailing winds in Northern Serbia have northwestern and southeastern directions. Circulation weather types over Serbia are presented in order to determine the connections between the synoptic circulations and prevailing surface winds. Three controlling pressure centers, i.e., the Mediterranean cyclone, Siberian high, and the Azores anticyclone, appear as the most important large-scale factors that influence the creation of the prevailing winds over Northern Serbia. Beside the synoptic cause of the prevailing winds, it is noted that the orography of the eastern Balkans has a major influence on the winds from the second quadrant. It was found that the frequencies of circulation weather types are in agreement with those of the prevailing winds over Northern Serbia.

  2. Potencial eólico na direção predominante do vento no Nordeste brasileiro Wind energy potential for the prevailing direction in Northeast Brazil

    Directory of Open Access Journals (Sweden)

    Bernardo B. da Silva

    2002-12-01

    Full Text Available Neste trabalho, foram utilizados dados horários de velocidade e direção do vento, provenientes de registros de anemógrafo Universal Fuess, a 10 m de altura, de 77 estações climatológicas pertencentes ao Instituto Nacional de Meteorologia (INMET, no período de janeiro de 1977 a dezembro de 1981. O objetivo da pesquisa foi a determinação da potência eólica média horária da direção predominante do vento em todas as estações selecionadas. Para tanto, identificou-se a direção predominante do vento de cada localidade e se estimaram os parâmetros da distribuição de Weibull, através dos quais se calculou a potência eólica média horária. Em função dos resultados apresentados neste trabalho, constatou-se que a direção predominante do vento no Nordeste do Brasil é de Leste, com flutuações para Sudeste e Nordeste. O ajuste do Método dos Momentos evidenciou-se melhor que o dos Mínimos Quadrados. Os Estados do Maranhão e Rio Grande do Norte apresentaram, respectivamente, o menor e maior potencial eólico. As estações de Alto Parnaíba, MA, e Acaraú, CE, apresentaram, mensalmente, a menor (0,022 W m-2 e a maior (138,302 W m-2 potência eólica, respectivamente.Hourly mean data of wind speed and direction, measured with a Fuess anemograph at 10 m height, were used in this study. These data were collected from January 1977 to December 1981 at 77 weather stations located in the Northeast of Brazil. The main objective of the study was to determine the wind energy potential for the predominant wind direction of selected stations; therefore, the identification of the relative frequency related to the hourly mean wind speed of the predominant direction was carried out. Then, the parameters, of a Weibull distribution related to the hourly mean wind speed of the predominant direction at each station were estimated by Moments and Graphical methods. The results show that the predominant wind direction in Northeast as a whole is

  3. Global empirical wind model for the upper mesosphere/lower thermosphere. I. Prevailing wind

    Directory of Open Access Journals (Sweden)

    Y. I. Portnyagin

    Full Text Available An updated empirical climatic zonally averaged prevailing wind model for the upper mesosphere/lower thermosphere (70-110 km, extending from 80°N to 80°S is presented. The model is constructed from the fitting of monthly mean winds from meteor radar and MF radar measurements at more than 40 stations, well distributed over the globe. The height-latitude contour plots of monthly mean zonal and meridional winds for all months of the year, and of annual mean wind, amplitudes and phases of annual and semiannual harmonics of wind variations are analyzed to reveal the main features of the seasonal variation of the global wind structures in the Northern and Southern Hemispheres. Some results of comparison between the ground-based wind models and the space-based models are presented. It is shown that, with the exception of annual mean systematic bias between the zonal winds provided by the ground-based and space-based models, a good agreement between the models is observed. The possible origin of this bias is discussed.

    Key words: Meteorology and Atmospheric dynamics (general circulation; middle atmosphere dynamics; thermospheric dynamics

  4. Projected changes in prevailing winds for transatlantic migratory birds under global warming.

    Science.gov (United States)

    La Sorte, Frank A; Fink, Daniel

    2017-03-01

    A number of terrestrial bird species that breed in North America cross the Atlantic Ocean during autumn migration when travelling to their non-breeding grounds in the Caribbean or South America. When conducting oceanic crossings, migratory birds tend to associate with mild or supportive winds, whose speed and direction may change under global warming. The implications of these changes for transoceanic migratory bird populations have not been addressed. We used occurrence information from eBird (1950-2015) to estimate the geographical location of population centres at a daily temporal resolution across the annual cycle for 10 transatlantic migratory bird species. We used this information to estimate the location and timing of autumn migration within the transatlantic flyway. We estimated how prevailing winds are projected to change within the transatlantic flyway during this time using daily wind speed anomalies (1996-2005 and 2091-2100) from 29 Atmosphere-Ocean General Circulation Models implemented under CMIP5. Autumn transatlantic migrants have the potential to encounter strong westerly crosswinds early in their transatlantic journey at intermediate and especially high migration altitudes, strong headwinds at low and intermediate migration altitudes within the Caribbean that increase in strength as the season progresses, and weak tailwinds at intermediate and high migration altitudes east of the Caribbean. The CMIP5 simulations suggest that, during this century, the likelihood of autumn transatlantic migrants encountering strong westerly crosswinds will diminish. As global warming progresses, the need for species to compensate or drift under the influence of strong westerly crosswinds during the initial phase of their autumn transatlantic journey may be diminished. Existing strategies that promote headwind avoidance and tailwind assistance will likely remain valid. Thus, climate change may reduce time and energy requirements and the chance of mortality or

  5. Monthly mean climatology of the prevailing winds and tides in the Arctic mesosphere/lower thermosphere

    Directory of Open Access Journals (Sweden)

    Y. I. Portnyagin

    2004-11-01

    Full Text Available The Arctic MLT wind regime parameters measured at the ground-based network of MF and meteor radar stations (Andenes 69° N, Tromsø 70° N, Esrange 68° N, Dixon 73.5° N, Poker Flat 65° N and Resolute Bay 75° N are discussed and compared with those observed in the mid-latitudes. The network of the ground-based MF and meteor radars for measuring winds in the Arctic upper mesosphere and lower thermosphere provides an excellent opportunity for study of the main global dynamical structures in this height region and their dependence from longitude. Preliminary estimates of the differences between the measured winds and tides from the different radar types, situated 125-273km apart (Tromsø, Andenes and Esrange, are provided. Despite some differences arising from using different types of radars it is possible to study the dynamical wind structures. It is revealed that most of the observed dynamical structures are persistent from year to year, thus permitting the analysis of the Arctic MLT dynamics in a climatological sense. The seasonal behaviour of the zonally averaged wind parameters is, to some extent, similar to that observed at the moderate latitudes. However, the strength of the winds (except the prevailing meridional wind and the diurnal tide amplitudes in the Arctic MLT region is, in general, less than that detected at the moderate latitudes, decreasing toward the pole. There are also some features in the vertical structure and seasonal variations of the Arctic MLT winds which are different from the expectations of the well-known empirical wind models CIRA-86 and HWM-93. The tidal phases show a very definite longitudinal dependence that permits the determination of the corresponding zonal wave numbers. It is shown that the migrating tides play an important role in the dynamics of the Arctic MLT region. However, there are clear indications with the presence in some months of non-migrating tidal modes of significant appreciable amplitude.

  6. A joint probability density function of wind speed and direction for wind energy analysis

    International Nuclear Information System (INIS)

    Carta, Jose A.; Ramirez, Penelope; Bueno, Celia

    2008-01-01

    A very flexible joint probability density function of wind speed and direction is presented in this paper for use in wind energy analysis. A method that enables angular-linear distributions to be obtained with specified marginal distributions has been used for this purpose. For the marginal distribution of wind speed we use a singly truncated from below Normal-Weibull mixture distribution. The marginal distribution of wind direction comprises a finite mixture of von Mises distributions. The proposed model is applied in this paper to wind direction and wind speed hourly data recorded at several weather stations located in the Canary Islands (Spain). The suitability of the distributions is judged from the coefficient of determination R 2 . The conclusions reached are that the joint distribution proposed in this paper: (a) can represent unimodal, bimodal and bitangential wind speed frequency distributions, (b) takes into account the frequency of null winds, (c) represents the wind direction regimes in zones with several modes or prevailing wind directions, (d) takes into account the correlation between wind speeds and its directions. It can therefore be used in several tasks involved in the evaluation process of the wind resources available at a potential site. We also conclude that, in the case of the Canary Islands, the proposed model provides better fits in all the cases analysed than those obtained with the models used in the specialised literature on wind energy

  7. Modelling Wind for Wind Farm Layout Optimization Using Joint Distribution of Wind Speed and Wind Direction

    OpenAIRE

    Ju Feng; Wen Zhong Shen

    2015-01-01

    Reliable wind modelling is of crucial importance for wind farm development. The common practice of using sector-wise Weibull distributions has been found inappropriate for wind farm layout optimization. In this study, we propose a simple and easily implementable method to construct joint distributions of wind speed and wind direction, which is based on the parameters of sector-wise Weibull distributions and interpolations between direction sectors. It is applied to the wind measurement data a...

  8. PREVAILING DUST-TRANSPORT DIRECTIONS ON COMET 67P/CHURYUMOV–GERASIMENKO

    Energy Technology Data Exchange (ETDEWEB)

    Kramer, Tobias; Noack, Matthias [Konrad-Zuse-Zentrum für Informationstechnik, Takustrasse 7, D-14195 Berlin (Germany)

    2015-11-10

    Dust transport and deposition behind larger boulders on the comet 67P/Churyumov–Gerasimenko (67P/C–G) have been observed by the Rosetta mission. We present a mechanism for dust-transport vectors based on a homogeneous surface activity model incorporating in detail the topography of 67P/C–G. The combination of gravitation, gas drag, and Coriolis force leads to specific dust transfer pathways, which for higher dust velocities fuel the near-nucleus coma. By distributing dust sources homogeneously across the whole cometary surface, we derive a global dust-transport map of 67P/C–G. The transport vectors are in agreement with the reported wind-tail directions in the Philae descent area.

  9. Influence of local wind speed and direction on wind power dynamics – Application to offshore very short-term forecasting

    DEFF Research Database (Denmark)

    Gallego, Cristobal; Pinson, Pierre; Madsen, Henrik

    2011-01-01

    on one-step ahead forecasting and a time series resolution of 10 min. It has been found that the local wind direction contributes to model some features of the prevailing winds, such as the impact of the wind direction on the wind variability, whereas the non-linearities related to the power......Wind power time series usually show complex dynamics mainly due to non-linearities related to the wind physics and the power transformation process in wind farms. This article provides an approach to the incorporation of observed local variables (wind speed and direction) to model some...... of these effects by means of statistical models. To this end, a benchmarking between two different families of varyingcoefficient models (regime-switching and conditional parametric models) is carried out. The case of the offshore wind farm of Horns Rev in Denmark has been considered. The analysis is focused...

  10. Modelling Wind for Wind Farm Layout Optimization Using Joint Distribution of Wind Speed and Wind Direction

    DEFF Research Database (Denmark)

    Feng, Ju; Shen, Wen Zhong

    2015-01-01

    Reliable wind modelling is of crucial importance for wind farm development. The common practice of using sector-wise Weibull distributions has been found inappropriate for wind farm layout optimization. In this study, we propose a simple and easily implementable method to construct joint distribu......Reliable wind modelling is of crucial importance for wind farm development. The common practice of using sector-wise Weibull distributions has been found inappropriate for wind farm layout optimization. In this study, we propose a simple and easily implementable method to construct joint...... quite well in terms of the coefficient of determination R-2. Then, the best of these joint distributions is used in the layout optimization of the Horns Rev 1 wind farm and the choice of bin sizes for wind speed and wind direction is also investigated. It is found that the choice of bin size for wind...... direction is especially critical for layout optimization and the recommended choice of bin sizes for wind speed and wind direction is finally presented....

  11. Direct Drive Technology for Wind Turbine Applications

    OpenAIRE

    Azar, Ziad

    2014-01-01

    Siemens Wind Power have developed direct-drive (DD) wind turbine technology over the past decade to meet the future demand for cost effective and reliable onshore and offshore wind power. The increasing power requirements from the industry resulting in higher torque requirements in the drive train, has made it necessary to reduce the complexity and improve reliability of wind turbines by going to DD generator technology.

  12. Effect of Wind Direction on ENVISAT ASAR Wind Speed Retrieval

    DEFF Research Database (Denmark)

    Takeyama, Yuko; Ohsawa, Teruo; Kozai, Katsutoshi

    2010-01-01

    This paper presents an evaluation of effects of wind directions (NCEP, MANAL, QuickSCAT and WRF) on the sea surface wind speed retrieval from 75 ENVISAT ASAR images with four C-band Geophysical model functions, CMOD4, CMOD_IFR2, CMOD5 and CMOD5N at two target areas, Hiratsuka and Shirahama...

  13. Characterization of wind speed data according to wind direction

    Energy Technology Data Exchange (ETDEWEB)

    Torres, J.L.; Garcia, A.; Prieto, E. [Universidad Publica de Navarra, Pamplona (Spain). Dpto. Proyectos e Ingenieria Rural; Francisco, A. De [Universidad Politecnica de Madrid (Spain). Dpto. de Ingenieria Forestal

    1999-05-01

    Knowledge of the wind speed distribution and the most frequent wind directions is important when choosing wind turbines and when locating them. For this reason wind evaluation and characterization are important when forecasting output power. The data used here were collected from eleven meteorological stations distributed in Navarre, Spain. We obtained data for the period extending from 1992 to 1995, with each datum encompassing 10 minutes of time. Wind speed data of each station were gathered in eight directional sectors, each one extended over 45 degrees according to the direction from which the wind blows. The stations were grouped in two blocks: those under the influence of the Ebro valley and those in mountainous areas. For each group the Weibull parameters were estimated, (according to the Weibull probability paper because the Weibull distribution gives the best fit in this region). Kurtosis and skewness coefficients were estimated as well. The Weibull parameters, especially the scale parameter c, depend strongly on the direction considered, and both Weibull parameters show an increasing trend as the direction considered moves to the more dominant direction, while both kurtosis and skewness show a corresponding decreasing trend. (author)

  14. Wind measurement via direct detection lidar

    Science.gov (United States)

    Afek, I.; Sela, N.; Narkiss, N.; Shamai, G.; Tsadka, S.

    2013-10-01

    Wind sensing Lidar is considered a promising technology for high quality wind measurements required for various applications such as hub height wind resource assessment, power curve measurements and advanced, real time, forward looking turbine control. Until recently, the only available Lidar technology was based on coherent Doppler shift detection, whose market acceptance has been slow primarily due to its exuberant price. Direct detection Lidar technology provides an alternative to remote sensing of wind by incorporating high precision measurement, a robust design and an affordable price tag.

  15. Boundary-Layer Structure Near an Ice Edge as a Function of Wind Direction

    Science.gov (United States)

    1992-10-01

    variations in onthezeft. aue n 1962)h geostrophic wind direction (cx), particularly for flow sea breeze ( Estoque , 1962). approximately parallel to the...case with "ice on the left". The Estoque , M.A., 1962: The sea breeze as a function of position of maximum w is closely related to its the prevailing

  16. Numerical Investigation of Wind Conditions for Roof-Mounted Wind Turbines: Effects of Wind Direction and Horizontal Aspect Ratio of a High-Rise Cuboid Building

    Directory of Open Access Journals (Sweden)

    Takaaki Kono

    2016-11-01

    Full Text Available From the viewpoint of installing small wind turbines (SWTs on rooftops, this study investigated the effects of wind direction and horizontal aspect ratio (HAR = width/length of a high-rise cuboid building on wind conditions above the roof by conducting large eddy simulations (LESs. The LES results confirmed that as HAR decreases (i.e., as the building width decreases, the variation in wind velocity over the roof tends to decrease. This tendency is more prominent as the angle between the wind direction and the normal vector of the building’s leeward face with longer roof edge increases. Moreover, at windward corners of the roof, wind conditions are generally favorable at relatively low heights. In contrast, at the midpoint of the roof's windward edge, wind conditions are generally not favorable at relatively low heights. At leeward representative locations of the roof, the bottoms of the height range of favorable wind conditions are typically higher than those at the windward representative locations, but the favorable wind conditions are much better at the leeward representative locations. When there is no prevailing wind direction, the center of the roof is more favorable for installing SWTs than the corners or the edge midpoints of the roof.

  17. Radiotelemetric Analysis of the Effects of Prevailing Wind Direction on Mormon Cricket Migratory Band Movement

    Science.gov (United States)

    During outbreaks, flightless Mormon crickets [Anabrus simplex Haldeman (Orthoptera: Tettigoniidae)] form large mobile groups known as migratory bands. These bands can contain millions of individuals that march en masse across the landscape. The role of environmental cues in influencing the movement ...

  18. Direct Interval Forecasting of Wind Power

    DEFF Research Database (Denmark)

    Wan, Can; Xu, Zhao; Pinson, Pierre

    2013-01-01

    This letter proposes a novel approach to directly formulate the prediction intervals of wind power generation based on extreme learning machine and particle swarm optimization, where prediction intervals are generated through direct optimization of both the coverage probability and sharpness, wit......, without the prior knowledge of forecasting errors. The proposed approach has been proved to be highly efficient and reliable through preliminary case studies using real-world wind farm data, indicating a high potential of practical application.......This letter proposes a novel approach to directly formulate the prediction intervals of wind power generation based on extreme learning machine and particle swarm optimization, where prediction intervals are generated through direct optimization of both the coverage probability and sharpness...

  19. Directly driven generators for wind power applications

    Energy Technology Data Exchange (ETDEWEB)

    Lampola, P. [Helsinki Univ. of Technology, Espoo (Finland). Lab. of Electromechanics

    1995-12-31

    The article deals with an analysis of directly driven, low-speed wind generators. The generators studied were a permanent-magnet synchronous machine and an asynchronous machine. The machines were compared with a typical generator of a wind power plant. The electromagnetic optimization of the machines was done by the finite element method. The rated power of the generators was 500 kW and the rotational speed was 40 rpm. (author)

  20. Influence of Wind Strength and Duration on Relative Hypoxia Reductions by Opposite Wind Directions in an Estuary with an Asymmetric Channel

    Directory of Open Access Journals (Sweden)

    Ping Wang

    2016-09-01

    Full Text Available Computer model experiments are applied to analyze hypoxia reductions for opposing wind directions under various speeds and durations in the north–south oriented, two-layer-circulated Chesapeake estuary. Wind’s role in destratification is the main mechanism in short-term reduction of hypoxia. Hypoxia can also be reduced by wind-enhanced estuarine circulation associated with winds that have down-estuary straining components that promote bottom-returned oxygen-rich seawater intrusion. The up-bay-ward along-channel component of straining by the southerly or easterly wind induces greater destratification than the down-bay-ward straining by the opposite wind direction, i.e., northerly or westerly winds. While under the modulation of the west-skewed asymmetric cross-channel bathymetry in the Bay’s hypoxic zone, the westward cross-channel straining by easterly or northerly winds causes greater destratification than its opposite wind direction. The wind-induced cross-channel circulation can be completed much more rapidly than the wind-induced along-channel circulation, and the former is usually more effective than the latter in destratification and hypoxia reduction in an early wind period. The relative importance of cross-channel versus along-channel circulation for a particular wind direction can change with wind speed and duration. The existence of month-long prevailing unidirectional winds in the Chesapeake is explored, and the relative hypoxia reductions among different prevailing directions are analyzed. Scenarios of wind with intermittent calm or reversing directions on an hourly scale are also simulated and compared.

  1. Current limiting characteristics of transformer type SFCL with coupled secondary windings according to its winding direction

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Sung Hun [Dept. of Electrical Engineering, Soongsil University, Seoul (Korea, Republic of); Han, Tae Hee [Dept. of Aero Materials Engineering, Jungwon University, Goesan (Korea, Republic of)

    2017-06-15

    In this paper, the current limiting characteristics of the transformer type superconducting fault current limiter (SFCL) with the two coupled secondary windings due to its winding direction were analyzed. To analyze the dependence of transient fault current limiting characteristics on the winding direction of the additional secondary winding, the fault current limiting tests of the SFCL with an additional secondary winding, wound as subtractive polarity winding and additive polarity winding, were carried out. The time interval of quench occurrence between two superconducting elements comprising the transformer type SFCL with the additional secondary winding was confirmed to be affected by the winding direction of the additional secondary winding. In case of the subtractive polarity winding of the additional secondary winding, the time interval of the quench occurrence in two superconducting elements was shorter than the case of the additive polarity winding.

  2. A multiple-fan active control wind tunnel for outdoor wind speed and direction simulation

    Science.gov (United States)

    Wang, Jia-Ying; Meng, Qing-Hao; Luo, Bing; Zeng, Ming

    2018-03-01

    This article presents a new type of active controlled multiple-fan wind tunnel. The wind tunnel consists of swivel plates and arrays of direct current fans, and the rotation speed of each fan and the shaft angle of each swivel plate can be controlled independently for simulating different kinds of outdoor wind fields. To measure the similarity between the simulated wind field and the outdoor wind field, wind speed and direction time series of two kinds of wind fields are recorded by nine two-dimensional ultrasonic anemometers, and then statistical properties of the wind signals in different time scales are analyzed based on the empirical mode decomposition. In addition, the complexity of wind speed and direction time series is also investigated using multiscale entropy and multivariate multiscale entropy. Results suggest that the simulated wind field in the multiple-fan wind tunnel has a high degree of similarity with the outdoor wind field.

  3. Full scale experimental analysis of wind direction changes (EOD)

    DEFF Research Database (Denmark)

    Hansen, Kurt Schaldemose

    2007-01-01

    wind direction gust amplitudes associated with the investigated European sites are low compared to the recommended IEC- values. However, these values, as function of the mean wind speed, are difficult to validate thoroughly due to the limited number of fully correlated measurements....... the magnitudes of a joint gust event defined by a simultaneously wind speed- and direction change in order to obtain an indication of the validity of the magnitudes specified in the IEC code. The analysis relates to pre-specified recurrence periods and is based on full-scale wind field measurements. The wind......A coherent wind speed and wind direction change (ECD) load case is defined in the wind turbine standard. This load case is an essential extreme load case that e.g. may be design driving for flap defection of active stall controlled wind turbines. The present analysis identifies statistically...

  4. directional considerations for extreme wind climatic events in the ...

    African Journals Online (AJOL)

    Dr Obe

    analysis is performed, taking into account directional wind information, as described in krishnasamy [2]. Wind speed data obtained from the meteorological section of the. Nigerian Civil Aviation Lagos were used for analysis. 5. DESIGN OF THE LINE SPAN. In order to obtain a reasonably accurate estimate of wind directions, ...

  5. The Crucial Records Number to Retrieve Offshore Directional Wind Distribution

    Science.gov (United States)

    Zhu, X.; Li, Z.; Yang, X.

    2017-02-01

    The wind energy production estimates are very important to a wind power project. And, the remote sensing technique has been widely used to obtain the offshore wind speed and direction which could be used to calculate the wind energy of potential wind farm. However, the directional wind energy distributions are rarely studied, which also play important roles in analysis of wind farms’ potential power. In this article, the minimum number of records to obtain offshore directional wind distribution is stated by simulation experiment on In-situ dataset. The NDBC buoy dataset is randomly and multiply sampled to build new dataset under different numbers of observation records, which vary from 21 to 800. The resample under the same number of observation is repeated for 100 times to build dataset group. The directional wind distribution of new dataset is compared with the one of original buoy dataset, and errors made by dataset with fewer records are calculated. Besides, the 10th largest error in the sampled dataset group, which have the same number of observation records, is regarded as the error bound for those dataset. The change rule of the error bound is shown by fitted curves. Based on the fitted curves, minimum number of records is calculated. By this simulation experiment, the minimum number of records to represent wind direction frequency is 350, and 800 for annual direction distributions of wind energy density. To reduce the number of records needed in retrieval, some methods are discussed and tested.

  6. Structural Flexibility of Large Direct Drive Generators for Wind Turbines

    NARCIS (Netherlands)

    Shrestha, G.

    2013-01-01

    The trend in wind energy is towards large offshore wind farms. This trend has led to the demand for high reliability and large single unit wind turbines. Different energy conversion topologies such as multiple stage geared generators, single stage geared generators and gearless (direct drive)

  7. Effectiveness of WRF wind direction for retrieving coastal sea surface wind from synthetic aperture radar

    DEFF Research Database (Denmark)

    Takeyama, Yuko; Ohsawa, Teruo; Kozai, Katsutoshi

    2013-01-01

    Wind direction is required as input to the geophysical model function (GMF) for the retrieval of sea surface wind speed from a synthetic aperture radar (SAR) images. The present study verifies the effectiveness of using the wind direction obtained from the weather research and forecasting model...... directions: the meso‐analysis of the Japan Meteorological Agency (MANAL), the SeaWinds microwave scatterometer on QuikSCAT and the National Center for Environmental Prediction final operational global analysis data (NCEP FNL). In comparison with the errors of the SAR‐retrieved wind speeds obtained using...

  8. Temperature Effects on the Wind Direction Measurement of 2D Solid Thermal Wind Sensors

    Science.gov (United States)

    Chen, Bei; Zhu, Yan-Qing; Yi, Zhenxiang; Qin, Ming; Huang, Qing-An

    2015-01-01

    For a two-dimensional solid silicon thermal wind sensor with symmetrical structure, the wind speed and direction information can be derived from the output voltages in two orthogonal directions, i.e., the north-south and east-west. However, the output voltages in these two directions will vary linearly with the ambient temperature. Therefore, in this paper, a temperature model to study the temperature effect on the wind direction measurement has been developed. A theoretical analysis has been presented first, and then Finite Element Method (FEM) simulations have been performed. It is found that due to symmetrical structure of the thermal wind sensor, the temperature effects on the output signals in the north-south and east-west directions are highly similar. As a result, the wind direction measurement of the thermal wind sensor is approximately independent of the ambient temperature. The experimental results fit the theoretical analysis and simulation results very well. PMID:26633398

  9. Directional analysis of extreme winds under mixed climate conditions

    CSIR Research Space (South Africa)

    Kruger, A

    2013-07-01

    Full Text Available Directional statistics provide design engineers with the opportunity to realise considerable cost savings, but these are not yet provided for in the South African standard for wind loading. The development of the directional statistics of extreme...

  10. Wind directing correlation and vertical temperature gradient correlation with the wind direction amplitud variation at Angra dos Reis site

    International Nuclear Information System (INIS)

    Nicolli, D.

    1982-08-01

    Two studies are presented: an analysis of air flow characteristics at the Itaorna site, in Angra dos Reis by correlation of wind directions measured simultaneosly on four meteorological masts, and a tentative correlation of vertical temperature gradient with the wind fluctuation standard deviation. It's concluded that the wind directions change vertical and horizontally and the wind direction fluctuation amplitude holds no correlation with the vertical temperature gradient, and therefore it should not be used as an alternative for determination of stability categories. (Author) [pt

  11. Passively cooled direct drive wind turbine

    Science.gov (United States)

    Costin, Daniel P [Chelsea, VT

    2008-03-18

    A wind turbine is provided that passively cools an electrical generator. The wind turbine includes a plurality of fins arranged peripherally around a generator house. Each of the fins being oriented at an angle greater than zero degrees to allow parallel flow of air over the fin. The fin is further tapered to allow a constant portion of the fin to extend beyond the air stream boundary layer. Turbulence initiators on the nose cone further enhance heat transfer at the fins.

  12. Climatology of Wind Direction Fluctuations at Risø

    DEFF Research Database (Denmark)

    Kristensen, Leif; Panofsky, H. A.

    1976-01-01

    Standard deviations of wind direction fluctuations at 76 m at Risø for the first half year of 1975 have been analyzed as functions of wind speed and temperature lapse rate, either measured near the surface or near the level of the azimuth variations. Between 31 and 37% of the variance of the stan......Standard deviations of wind direction fluctuations at 76 m at Risø for the first half year of 1975 have been analyzed as functions of wind speed and temperature lapse rate, either measured near the surface or near the level of the azimuth variations. Between 31 and 37% of the variance...

  13. Wind speed and direction shears with associated vertical motion during strong surface winds

    Science.gov (United States)

    Alexander, M. B.; Camp, D. W.

    1984-01-01

    Strong surface winds recorded at the NASA 150-Meter Ground Winds Tower facility at Kennedy Space Center, Florida, are analyzed to present occurrences representative of wind shear and vertical motion known to be hazardous to the ascent and descent of conventional aircraft and the Space Shuttle. Graphical (percentage frequency distributions) and mathematical (maximum, mean, standard deviation) descriptions of wind speed and direction shears and associated updrafts and downdrafts are included as functions of six vertical layers and one horizontal distance for twenty 5-second intervals of parameters sampled simultaneously at the rate of ten per second during a period of high surface winds.

  14. Potential bias in estimates of abundance and distribution of North Sea cod (Gadus morhua) due to strong winds prevailing prior or during a survey

    DEFF Research Database (Denmark)

    Wieland, Kai; Olesen, Hans Jakob; Pedersen, Eva Maria

    2011-01-01

    The impact of strong winds on catches of cod (Gadus morhua) was studied using different fishing methods during small-scale surveys with commercial fishing vessels in the north-eastern central North Sea. Catch per unit effort of a flyshooter and a trawler were considerably lower in the shallower...

  15. Wind direction variations in the natural wind – A new length scale

    DEFF Research Database (Denmark)

    Johansson, Jens; Christensen, Silas Sverre

    2018-01-01

    During an observation period of e.g. 10min, the wind direction will differ from its mean direction for short periods of time, and a body of air will pass by from that direction before the direction changes once again. The present paper introduces a new length scale which we have labeled the angul...

  16. Wind direction variability in Afternoon and Sunset Turbulence

    Science.gov (United States)

    Nilsson, Erik; Lothon, Marie; Lohou, Fabienne; Mahrt, Larry

    2014-05-01

    Understanding wind direction (WD) variability better is important for several reasons. Air pollution models need information about how variable wind direction is in different conditions (Davies and Thomson 1999). Accurate predictions of dispersion are important for human health and safety and allow for adaptation planning (Nagle et al. 2011). Other applications include horizontal diffusion, efficiency and fatigue of wind machines and air-sea interaction (Mahrt 2011). Most studies of wind direction variability have focused on nocturnal conditions because of greater variability in light winds. Modelling WD variability in transition periods when both mean wind speed and variance of the wind components are in a state of change can, however, also be very challenging and has not been the focus of earlier studies. The evening transitioning to the nocturnal boundary layer can play an important role in the diffusion process of pollutants and scalars emitted at surface and transported within the atmosphere. The Boundary Layer Late Afternoon and Sunset Turbulence (BLLAST) field campaign that took place in southern France in June and July 2011 focused on the decaying turbulence of the late afternoon boundary layer and related issues (Lothon et al. 2012). We analyse field measurements from BLLAST to investigate WD variability in the evening transition period. Standard deviations of horizontal wind direction fluctuations in the lowest 60 m of the boundary layer have been examined for dependence on mean wind speed, higher order moments and averaging time. Measurement results are interpreted using measured and idealized probability density functions of horizontal wind vectors. These are also used to develop analytical functions describing how WD variability depends on wind speed, variance and other controlling factors in the atmospheric boundary layer. References: Davies B.M., Thomson D.J., 1999. Comparison of some parameterizations of wind direction variability with observations

  17. Summertime winds and direct cyclonic circulation: observations from Lake Geneva

    Directory of Open Access Journals (Sweden)

    U. Lemmin

    Full Text Available Records of wind, air temperature and air pressure from nine stations, situated along the shoreline of Lake Geneva, Switzerland, were analyzed for the summer period May to September. At all stations the consistent appearance of significant spectral peaks and changes in wind direction at the diurnal frequency indicates the importance of lake-land breezes. It is shown that the surrounding topography has a strong modifying effect (temporal and spatial on the lake-land breeze. Superimposed on this cyclic wind pattern, short episodes of strong winds with long fetch over parts of Lake Geneva are regularly observed. Both of these winds exert a spatially variable wind stress over the lake surface on the same time scale. Typical examples of the expected lake's response are presented, among them the seasonally persistent gyre in the central part of the lake. Evidence is provided that this dominant circulation is part of a direct cyclonic circulation, generated by the curl of the diurnal wind field. It is concluded that the mean circulation is caused by these winds and affected by the topography of the surrounding land.

  18. Wind turbine having a direct-drive drivetrain

    Science.gov (United States)

    Bevington, Christopher M.; Bywaters, Garrett L.; Coleman, Clint C.; Costin, Daniel P.; Danforth, William L.; Lynch, Jonathan A.; Rolland, Robert H.

    2008-10-07

    A wind turbine (100) comprising an electrical generator (108) that includes a rotor assembly (112). A wind rotor (104) that includes a wind rotor hub (124) is directly coupled to the rotor assembly via a simplified connection. The wind rotor and generator rotor assembly are rotatably mounted on a central spindle (160) via a bearing assembly (180). The wind rotor hub includes an opening (244) having a diameter larger than the outside diameter of the central spindle adjacent the bearing assembly so as to allow access to the bearing assembly from a cavity (380) inside the wind rotor hub. The spindle is attached to a turret (140) supported by a tower (136). Each of the spindle, turret and tower has an interior cavity (172, 176, 368) that permits personnel to traverse therethrough to the cavity of the wind rotor hub. The wind turbine further includes a frictional braking system (276) for slowing, stopping or keeping stopped the rotation of the wind rotor and rotor assembly.

  19. Direct calculation of wind turbine tip loss

    DEFF Research Database (Denmark)

    Wood, D.H.; Okulov, Valery; Bhattacharjee, D.

    2016-01-01

    . We develop three methods for the direct calculation of the tip loss. The first is the computationally expensive calculation of the velocities induced by the helicoidal wake which requires the evaluation of infinite sums of products of Bessel functions. The second uses the asymptotic evaluation...

  20. Multi-Pole HTS Generators for Direct Drive Wind Turbines

    DEFF Research Database (Denmark)

    Jensen, Bogi Bech; Abrahamsen, Asger Bech; Seiler, Eugen

    In this presentation the feasibility of installing a 5MW direct drive superconducting generator for an offshore wind turbine is presented. The reference turbine is a geared 5MW wind turbine that has been installed offshore and has been documented extensively by the National Renewable Energy...... on two different types of coated conductor. In the specific design the allowable current density was 300A/mm^2 for tape 1 and 70A/mm^2 for tape 2. The design is analytical, based on magnetic circuit analysis, which is validated by finite element modelling. The conclusion is that the either price...... or the performance of the coated conductor has to improve significantly (by a factor of 10 or more) in order for HTS generators to become feasible in direct drive offshore wind turbines. This price/performance improvement is not unrealistic in the coming decade. Additionally the reliability of such machines...

  1. directional considerations for extreme wind climatic events in the ...

    African Journals Online (AJOL)

    Dr Obe

    This paper takes a look at the importance and role of probability concepts structural design of transmission line. The reliability of transmission structure is ... results in a Gumbel Type 1 distribution. Sample fit plot, directional wind speed plots ... design process involves sizing of component to withstand a few carefully selected.

  2. Design Tool for Direct Drive Wind Turbine Generators

    DEFF Research Database (Denmark)

    Leban, Krisztina Monika

    The current work offers a comparison of the proposed machine geometries for 6 [MW] direct drive wind generator candidates with the prospective of up scaling to 20MW. The suggestions are based on a design tool especially built for this investigation. The in-built flexibility of the design tool gives...

  3. 5MW Direct Drive Wind Turbine Generator Design

    DEFF Research Database (Denmark)

    Zaidi, Arsalan; Senn, Lucile; Ortega, Iratxe

    2012-01-01

    A 5MW direct drive offshore wind turbine generator was studied and simulated using Vector Fields OPERA. This software allows calculation of the flux density, force, torque, and eddy currents in the machine at different rotor positions. Based on the data obtained from the model, initial assumptions...

  4. Induction Generators for Direct-Drive Wind Turbines

    DEFF Research Database (Denmark)

    Henriksen, Matthew Lee; Jensen, Bogi Bech

    2011-01-01

    This paper considers the use of a squirrel cage induction generator for a direct-drive wind turbine. Advantages of this topology include a simple/rugged construction, and no need for permanent magnets. A major focus of this paper is the choice of an appropriate pole number. An iterative, analytical...

  5. Wind gust measurements using pulsed Doppler wind-lidar: comparison of direct and indirect techniques

    DEFF Research Database (Denmark)

    wind vector, we need information from at least three different lines of sight pointing towards different directions. The instrument sensitivity depends on the amount of aerosol present and the velocity measurement uncertainty is directly related to the amount of signal. With the commercial lidars...... traditionally used today it takes several seconds to measure each line of sight with sufficient sensitivity and therefore the temporal resolution of the wind measurement is of the order of tens of seconds, which is not sufficient for gusts. Here we deploy a fast scanning lidar (temporal resolution for a scan...

  6. Influence of wind direction on pollen concentration in the atmosphere

    Science.gov (United States)

    Silva Palacios, I.; Tormo Molina, R.; Muñoz Rodríguez, A. F.

    The daily pollen concentration in the atmosphere of Badajoz (SW Spain) was analysed over a 6-year period (1993-1998) using a volumetric aerobiological trap. The results for the main pollination period are compared with the number of hours of wind each day in the four quadrants: 1 (NE), 2 (SE), 3 (SW) and 4 (NW). The pollen source distribution allowed 16 pollen types to be analysed as a function of their distribution in the four quadrants with respect to the location of the trap. Four of them correspond to species growing in an irrigated farmland environment (Amaranthaceae-Chenopodiaceae, Plantago, Scirpus, and Typha), five to riparian and woodland species (Salix, Fraxinus, Alnus, Populus, and Eucalyptus), four to urban ornamentals (Ulmus, Arecaceae, Cupressaceae, and Casuarina), and three which include the most frequent pollen grains of widely distributed species (Poaceae, Quercus, and Olea). The results show that the distribution of the sources and the wind direction play a very major role in determining the pollen concentration in the atmosphere when these sources are located in certain quadrants, and that the widely distributed pollen sources show no relationship with wind direction. In some years the values of the correlations were not maintained, which leads one to presume that, in order to draw significant conclusions and establish clear patterns of the influence of wind direction, a continuous and more prolonged study will be required.

  7. Assessing the effect of wind speed/direction changes on urban heat island intensity of Istanbul.

    Science.gov (United States)

    Perim Temizoz, Huriye; Unal, Yurdanur S.

    2017-04-01

    Assessing the effect of wind speed/direction changes on urban heat island intensity of Istanbul. Perim Temizöz, Deniz H. Diren, Cemre Yürük and Yurdanur S. Ünal Istanbul Technical University, Department of Meteorological Engineering, Maslak, Istanbul, Turkey City or metropolitan areas are significantly warmer than the outlying rural areas since the urban fabrics and artificial surfaces which have different radiative, thermal and aerodynamic features alter the surface energy balance, interact with the regional circulation and introduce anthropogenic sensible heat and moisture into the atmosphere. The temperature contrast between urban and rural areas is most prominent during nighttime since heat is absorbed by day and emitted by night. The intensity of the urban heat island (UHI) vary considerably depending on the prevailent meteorological conditions and the characteristics of the region. Even though urban areas cover a small fraction of Earth, their climate has greater impact on the world's population. Over half of the world population lives in the cities and it is expected to rise within the coming decades. Today almost one fifth of the Turkey's population resides in Istanbul with the percentage expected to increase due to the greater job opportunities compared to the other cities. Its population has been increased from 2 millions to 14 millions since 1960s. Eventually, the city has been expanded tremendously within the last half century, shifting the landscape from vegetation to built up areas. The observations of the last fifty years over Istanbul show that the UHI is most pronounced during summer season. The seasonal temperature differences between urban and suburban sites reach up to 3 K and roughly haft degree increase in UHI intensity is observed after 2000. In this study, we explore the possible range of heat load and distribution over Istanbul for different prevailing wind conditions by using the non-hydrostatic MUKLIMO3 model developed by DWD

  8. Direct employment in the wind energy sector: An EU study

    International Nuclear Information System (INIS)

    Blanco, Maria Isabel; Rodrigues, Gloria

    2009-01-01

    Wind energy is often said to have positive effects on employment, but few studies have systematically dealt with this matter. This article presents estimates of direct wind energy employment in all EU countries, gathered for the first time. By using a thematic survey, the authors have been able to analyse aspects such as gender distribution, company profiles and the shortage of skilled workers reported by wind energy companies. The outcomes show that wind energy deployment creates a significant number of jobs (over 104,000 in 2008), and does so at a time when other energy sectors are shrinking. There is a clear relationship between MW installed and number of jobs, but the use of a single EU job/MW ratio is not feasible, due to differences in the export/import capacity. Wind turbine manufacturers-including major sub-components-are responsible for the lion's share of the jobs, and there is a marked prevalence of males in the workforce. The scarcity of specialist roles-project managers, engineers and O and M technicians-is not likely to be solved unless a series of educational, mobility and dissemination measures are put into practice.

  9. Design Preliminaries for Direct Drive under Water Wind Turbine Generator

    DEFF Research Database (Denmark)

    Leban, Krisztina Monika; Ritchie, Ewen; Argeseanu, Alin

    2012-01-01

    This paper focuses on the preliminary design process of a 20 MW electric generator. The application calls for an offshore, vertical axis, direct drive wind turbine. Arguments for selecting the type of electric machine for the application are presented and discussed. Comparison criteria for deciding...... on a type of machine are listed. Additional constraints emerging from the direct drive, vertical axis concepts are considered. General rules and a preliminary algorithm are discussed for the machine selected to be most suitable for the imposed conditions....

  10. Testing of a direct drive generator for wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Sondergaard, L.M. [Riso National Laboratory, Roskilde (Denmark)

    1996-12-31

    The normal drive train of a wind turbine consists a gearbox and a 4 to 8 poles asynchronous generator. The gearbox is an expensive and unreliable components and this paper deals with testing of a direct drive synchronous generator for a gearless wind turbine. The Danish company Belt Electric has constructed and manufactured a 27 kW prototype radial flux PM-generator (DD600). They have used cheap hard ferrite magnets in the rotor of this PM-generator. This generator has been tested at Riso and the test results are investigated and analyzed in this paper. The tests have been done with three different load types (1: resistance; 2: diode rectifier, DC-capacitor, resistance; 3: AC-capacitor, diode rectifier, DC-capacitor, resistance). 1 ref., 9 figs., 5 tabs.

  11. Dependence of the wind climate of Ireland on the direction distribution of geostrophic wind; Die Abhaengigkeit des Windklimas von Irland von der Richtungsverteilung des geostrophischen Windes

    Energy Technology Data Exchange (ETDEWEB)

    Frank, H.P. [Forskningcenter Risoe, Roskilde (Denmark). Afdelingen for Vindenergi og Atmosfaerefysik

    1998-01-01

    The wind climate of Ireland is calculated using the Karlsruhe Atmospheric Mesoscale Model KAMM. The dependence of the simulated wind energy on the direction distribution of geostrophic wind is studied. As geostrophic winds from the south-west are most frequent, sites on the north-west coast are particularly suited for wind power stations. In addition, geostrophic wind increases from the south-east to the north-west. (orig.) [Deutsch] Das Windklima von Irland wurde mit dem Karlsruher Atmosphaerischen Mesoskaligen Modell KAMM berechnet. Hier wird die Abhaengigkeit der simultierten Windenergie von der Richtungsverteilung des geostrophischen Windes untersucht. Da geostrophische Winde aus Suedwest am haeufigsten vorkommen, eignet sich besonders die Nordwestkueste als Standort fuer Windkraftanlagen. Zusaetzlich nimmt auch der mittlere geostrophische Wind von Suedost nach Nordwest zu. (orig.)

  12. Design Optimization and Site Matching of Direct-Drive Permanent Magnet Wind Generator Systems

    DEFF Research Database (Denmark)

    Li, H.; Chen, Zhe

    2009-01-01

    of the maximum wind energy capture, the rotor diameter and the rated wind speed of a direct-drive wind turbine with the optimum PM generator are determined. The annual energy output (AEO) is also presented using the Weibull density function. Finally, the maximum AEO per cost (AEOPC) of the optimized wind...

  13. Markov Chain model for the stochastic behaviors of wind-direction data

    International Nuclear Information System (INIS)

    Masseran, Nurulkamal

    2015-01-01

    Highlights: • I develop a Markov chain model to describe about the stochastic and probabilistic behaviors of wind direction data. • I describe some of the theoretical arguments regarding the Markov chain model in term of wind direction data. • I suggest a limiting probabilities approach to determine a dominant directions of wind blow. - Abstract: Analyzing the behaviors of wind direction can complement knowledge concerning wind speed and help researchers draw conclusions regarding wind energy potential. Knowledge of the wind’s direction enables the wind turbine to be positioned in such a way as to maximize the total amount of captured energy and optimize the wind farm’s performance. In this paper, first-order and higher-order Markov chain models are proposed to describe the probabilistic behaviors of wind-direction data. A case study is conducted using data from Mersing, Malaysia. The wind-direction data are classified according to an eight-state Markov chain based on natural geographical directions. The model’s parameters are estimated using the maximum likelihood method and the linear programming formulation. Several theoretical arguments regarding the model are also discussed. Finally, limiting probabilities are used to determine a long-run proportion of the wind directions generated. The results explain the dominant direction for Mersing’s wind in terms of probability metrics

  14. Pollutant forecasting error based on persistence of wind direction

    International Nuclear Information System (INIS)

    Cooper, R.E.

    1978-01-01

    The purpose of this report is to provide a means of estimating the reliability of forecasts of downwind pollutant concentrations from atmospheric puff releases. These forecasts are based on assuming the persistence of wind direction as determined at the time of release. This initial forecast will be used to deploy survey teams, to predict population centers that may be affected, and to estimate the amount of time available for emergency response. Reliability of forecasting is evaluated by developing a cumulative probability distribution of error as a function of lapsed time following an assumed release. The cumulative error is determined by comparing the forecast pollutant concentration with the concentration measured by sampling along the real-time meteorological trajectory. It may be concluded that the assumption of meteorological persistence for emergency response is not very good for periods longer than 3 hours. Even within this period, the possibiity for large error exists due to wind direction shifts. These shifts could affect population areas totally different from those areas first indicated

  15. Comparison of superconducting generators and permanent magnet generators for 10-MW direct-drive wind turbines

    DEFF Research Database (Denmark)

    Liu, Dong; Polinder, Henk; Abrahamsen, Asger Bech

    2016-01-01

    Large offshore direct-drive wind turbines of 10-MW power levels are being extensively proposed and studied because of a reduced cost of energy. Conventional permanent magnet generators currently dominating the direct-drive wind turbine market are still under consideration for such large wind...

  16. Analysis of Transient Phenomena Due to a Direct Lightning Strike on a Wind Energy System

    OpenAIRE

    Rafael B. Rodrigues; Victor M. F. Mendes; João P. S. Catalão

    2012-01-01

    This paper is concerned with the protection of wind energy systems against the direct effects of lightning. As wind power generation undergoes rapid growth, lightning damages involving wind turbines have come to be regarded as a serious problem. Nevertheless, very few studies exist yet in Portugal regarding lightning protection of wind energy systems using numerical codes. A new case study is presented in this paper, based on a wind turbine with an interconnecting transformer, for the analysi...

  17. Modeling and Control of Direct Driven PMSG for Ultra Large Wind Turbines

    OpenAIRE

    Ahmed M. Hemeida; Wael A. Farag; Osama A. Mahgoub

    2011-01-01

    This paper focuses on developing an integrated reliable and sophisticated model for ultra large wind turbines And to study the performance and analysis of vector control on large wind turbines. With the advance of power electronics technology, direct driven multi-pole radial flux PMSG (Permanent Magnet Synchronous Generator) has proven to be a good choice for wind turbines manufacturers. To study the wind energy conversion systems, it is important to develop a wind turbin...

  18. Recent near-surface wind directions inferred from mapping sand ripples on Martian dunes

    Science.gov (United States)

    Liu, Zac Yung-Chun; Zimbelman, James R.

    2015-11-01

    The High Resolution Imaging Science Experiment (HiRISE) provides the capability to obtain orbital images of Mars that are of sufficient resolution to record wind ripple patterns on the surfaces of sand dunes. Ripple patterns provide valuable insights into aeolian erosion and deposition on Earth and Mars. In this study, we develop a systematic mapping procedure to examine sand ripple orientations and create surface process maps to evaluate the recent wind flow over the dunes, as well as the interplay of wind and dune shape. By carefully examining the morphology of the dunes and the location of grainflow and grainfall on dune slipfaces, the recent near-surface wind direction (short-term wind) can be identified. Results from the analysis of three dune fields on the floors of craters west of Hellas Basin show regional N, NW, SE, and ESE wind directions. In the three adjacent dune fields, surface process and flow maps suggest a complex wind pattern. The comparison of short-term wind with dune-constructing wind (long-term wind) shows NE and ESE winds may be persistent at least for the past thousands of years. The results also show that the orientation of inferred wind direction on linear dunes is correlated with the crestlines, which suggest that form-flow interaction may take place. The results of local wind flow documentation should improve Martian surface wind modeling and advance our understanding of sand transport, as well as the rates of sand mobility on both Mars and Earth.

  19. A note on the correlation between circular and linear variables with an application to wind direction and air temperature data in a Mediterranean climate

    Science.gov (United States)

    Lototzis, M.; Papadopoulos, G. K.; Droulia, F.; Tseliou, A.; Tsiros, I. X.

    2018-04-01

    There are several cases where a circular variable is associated with a linear one. A typical example is wind direction that is often associated with linear quantities such as air temperature and air humidity. The analysis of a statistical relationship of this kind can be tested by the use of parametric and non-parametric methods, each of which has its own advantages and drawbacks. This work deals with correlation analysis using both the parametric and the non-parametric procedure on a small set of meteorological data of air temperature and wind direction during a summer period in a Mediterranean climate. Correlations were examined between hourly, daily and maximum-prevailing values, under typical and non-typical meteorological conditions. Both tests indicated a strong correlation between mean hourly wind directions and mean hourly air temperature, whereas mean daily wind direction and mean daily air temperature do not seem to be correlated. In some cases, however, the two procedures were found to give quite dissimilar levels of significance on the rejection or not of the null hypothesis of no correlation. The simple statistical analysis presented in this study, appropriately extended in large sets of meteorological data, may be a useful tool for estimating effects of wind on local climate studies.

  20. Self-Powered Wind Sensor System for Detecting Wind Speed and Direction Based on a Triboelectric Nanogenerator.

    Science.gov (United States)

    Wang, Jiyu; Ding, Wenbo; Pan, Lun; Wu, Changsheng; Yu, Hua; Yang, Lijun; Liao, Ruijin; Wang, Zhong Lin

    2018-04-02

    The development of the Internet of Things has brought new challenges to the corresponding distributed sensor systems. Self-powered sensors that can perceive and respond to environmental stimuli without an external power supply are highly desirable. In this paper, a self-powered wind sensor system based on an anemometer triboelectric nanogenerator (a-TENG, free-standing mode) and a wind vane triboelectric nanogenerator (v-TENG, single-electrode mode) is proposed for simultaneously detecting wind speed and direction. A soft friction mode is adopted instead of a typical rigid friction for largely enhancing the output performance of the TENG. The design parameters including size, unit central angle, and applied materials are optimized to enhance sensitivity, resolution, and wide measurement scale. The optimized a-TENG could deliver an open-circuit voltage of 88 V and short-circuit current of 6.3 μA, corresponding to a maximum power output of 0.47 mW (wind speed of 6.0 m/s), which is capable of driving electronics for data transmission and storage. The current peak value of the a-TENG signal is used for analyzing wind speed for less energy consumption. Moreover, the output characteristics of a v-TENG are further explored, with six actual operation situations, and the v-TENG delivers fast response to the incoming wind and accurately outputs the wind direction data. As a wind sensor system, wind speed ranging from 2.7 to 8.0 m/s can be well detected (consistent with a commercial sensor) and eight regular directions can be monitored. Therefore, the fabricated wind sensor system has great potential in wireless environmental monitoring applications.

  1. Ceramic thermal wind sensor based on advanced direct chip attaching package

    International Nuclear Information System (INIS)

    Zhou Lin; Qin Ming; Chen Shengqi; Chen Bei

    2014-01-01

    An advanced direct chip attaching packaged two-dimensional ceramic thermal wind sensor is studied. The thermal wind sensor chip is fabricated by metal lift-off processes on the ceramic substrate. An advanced direct chip attaching (DCA) packaging is adopted and this new packaged method simplifies the processes of packaging further. Simulations of the advanced DCA packaged sensor based on computational fluid dynamics (CFD) model show the sensor can detect wind speed and direction effectively. The wind tunnel testing results show the advanced DCA packaged sensor can detect the wind direction from 0° to 360° and wind speed from 0 to 20 m/s with the error less than 0.5 m/s. The nonlinear fitting based least square method in Matlab is used to analyze the performance of the sensor. (semiconductor devices)

  2. Comparison of superconducting generators and permanent magnet generators for 10-MW direct-drive wind turbines

    DEFF Research Database (Denmark)

    Liu, Dong; Polinder, Henk; Abrahamsen, Asger Bech

    2016-01-01

    Large offshore direct-drive wind turbines of 10-MW power levels are being extensively proposed and studied because of a reduced cost of energy. Conventional permanent magnet generators currently dominating the direct-drive wind turbine market are still under consideration for such large wind...... turbines. In the meantime, superconducting generators (SCSGs) have been of particular interest to become a significant competitor because of their compactness and light weight. This paper compares the performance indicators of these two direct-drive generator types in the same 10-MW wind turbine under...

  3. Pattern recognition methods and air pollution source identification. [based on wind direction

    Science.gov (United States)

    Leibecki, H. F.; King, R. B.

    1978-01-01

    Directional air samplers, used for resolving suspended particulate matter on the basis of time and wind direction were used to assess the feasibility of characterizing and identifying emission source types in urban multisource environments. Filters were evaluated for 16 elements and X-ray fluorescence methods yielded elemental concentrations for direction, day, and the interaction of direction and day. Large numbers of samples are necessary to compensate for large day-to-day variations caused by wind perturbations and/or source changes.

  4. Dependence of the surf zone aerosol on wind direction and wind speed at a coastal site on the Baltic Sea

    Directory of Open Access Journals (Sweden)

    Tymon Zieliński

    2003-09-01

    Full Text Available Since 1992 lidar-based measurements have been carried out under various meteorological conditions and at various times of the year. The aerosol optical properties were determined in the marine boundary layer as a function of altitude using such factors as wind direction, duration and velocity and aerosol size distribution and concentration. It was confirmed that in all cases, the total aerosol concentration, size distribution and aerosol extinction increase with wind speed but decrease with altitude. In the range of wind velocities from 1 to 15 m s-1 the mean aerosol optical thickness of the atmosphere (VIS obtained from the lidar varied from 0.1 to 0.38 for offshore winds and from 0.01 to about 0.1 for onshore winds, while the Ångström parameter for VIS oscillated around 0.65 for onshore winds and around 1 for offshore winds. Both parameters depended strongly on the history of the air mass above the Baltic Sea. Such aerosol optical thicknesses are in agreement with those obtained by other researchers in the Baltic Sea area.

  5. LIDAR and SODAR Measurements of Wind Speed and Direction in Upland Terrain for Wind Energy Purposes

    Directory of Open Access Journals (Sweden)

    Eamon McKeogh

    2011-08-01

    Full Text Available Detailed knowledge of the wind resource is necessary in the developmental and operational stages of a wind farm site. As wind turbines continue to grow in size, masts for mounting cup anemometers—the accepted standard for resource assessment—have necessarily become much taller, and much more expensive. This limitation has driven the commercialization of two remote sensing (RS tools for the wind energy industry: The LIDAR and the SODAR, Doppler effect instruments using light and sound, respectively. They are ground-based and can work over hundreds of meters, sufficient for the tallest turbines in, or planned for, production. This study compares wind measurements from two commercial RS instruments against an instrumented mast, in upland (semi-complex terrain typical of where many wind farms are now being installed worldwide. With appropriate filtering, regression analyses suggest a good correlation between the RS instruments and mast instruments: The RS instruments generally recorded lower wind speeds than the cup anemometers, with the LIDAR more accurate and the SODAR more precise.

  6. Development of a Wind Directly Forced Heat Pump and Its Efficiency Analysis

    OpenAIRE

    Ching-Song Jwo; Zi-Jie Chien; Yen-Lin Chen; Chao-Chun Chien

    2013-01-01

    The requirements of providing electric energy through the wind-forced generator to the heat pump for water cooling and hot water heating grow significantly by now. This study proposes a new technique to directly adopt the wind force to drive heat pump systems, which can effectively reduce the energy conversion losses during the processes of wind force energy converting to electric energy and electric energy converting to kinetic energy. The operation of heat pump system transfers between chil...

  7. Direct Torque Control of a Small Wind Turbine with a Sliding-Mode Speed Controller

    Science.gov (United States)

    Sri Lal Senanayaka, Jagath; Karimi, Hamid Reza; Robbersmyr, Kjell G.

    2016-09-01

    In this paper. the method of direct torque control in the presence of a sliding-mode speed controller is proposed for a small wind turbine being used in water heating applications. This concept and control system design can be expanded to grid connected or off-grid applications. Direct torque control of electrical machines has shown several advantages including very fast dynamics torque control over field-oriented control. Moreover. the torque and flux controllers in the direct torque control algorithms are based on hvsteretic controllers which are nonlinear. In the presence of a sliding-mode speed control. a nonlinear control system can be constructed which is matched for AC/DC conversion of the converter that gives fast responses with low overshoots. The main control objectives of the proposed small wind turbine can be maximum power point tracking and soft-stall power control. This small wind turbine consists of permanent magnet synchronous generator and external wind speed. and rotor speed measurements are not required for the system. However. a sensor is needed to detect the rated wind speed overpass events to activate proper speed references for the wind turbine. Based on the low-cost design requirement of small wind turbines. an available wind speed sensor can be modified. or a new sensor can be designed to get the required measurement. The simulation results will be provided to illustrate the excellent performance of the closed-loop control system in entire wind speed range (4-25 m/s).

  8. 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.

  9. Field Calibration of Wind Direction Sensor to the True North and Its Application to the Daegwanryung Wind Turbine Test Sites

    Directory of Open Access Journals (Sweden)

    Jeong Wan Lee

    2008-12-01

    Full Text Available This paper proposes a field calibration technique for aligning a wind direction sensor to the true north. The proposed technique uses the synchronized measurements of captured images by a camera, and the output voltage of a wind direction sensor. The true wind direction was evaluated through image processing techniques using the captured picture of the sensor with the least square sense. Then, the evaluated true value was compared with the measured output voltage of the sensor. This technique solves the discordance problem of the wind direction sensor in the process of installing meteorological mast. For this proposed technique, some uncertainty analyses are presented and the calibration accuracy is discussed. Finally, the proposed technique was applied to the real meteorological mast at the Daegwanryung test site, and the statistical analysis of the experimental testing estimated the values of stable misalignment and uncertainty level. In a strict sense, it is confirmed that the error range of the misalignment from the exact north could be expected to decrease within the credibility level.

  10. A novel linear direct drive system for textile winding applications

    OpenAIRE

    Jakeman, N; Bullough, W; Bingham, Chris; Mellor, Phillip

    2003-01-01

    The paper describes the specification, modelling, magnetic design, thermal characteristics and control of a novel, high acceleration (up to 82g) brushless PM linear actuator with Halbach array, for textile package winding applications. Experimental results demonstrate the realisation of the actuator and induced performance advantages afforded to the phase lead, closed-loop position control scheme.

  11. An Improved Local Gradient Method for Sea Surface Wind Direction Retrieval from SAR Imagery

    Directory of Open Access Journals (Sweden)

    Lizhang Zhou

    2017-06-01

    Full Text Available Sea surface wind affects the fluxes of energy, mass and momentum between the atmosphere and ocean, and therefore regional and global weather and climate. With various satellite microwave sensors, sea surface wind can be measured with large spatial coverage in almost all-weather conditions, day or night. Like any other remote sensing measurements, sea surface wind measurement is also indirect. Therefore, it is important to develop appropriate wind speed and direction retrieval models for different types of microwave instruments. In this paper, a new sea surface wind direction retrieval method from synthetic aperture radar (SAR imagery is developed. In the method, local gradients are computed in frequency domain by combining the operation of smoothing and computing local gradients in one step to simplify the process and avoid the difference approximation. This improved local gradients (ILG method is compared with the traditional two-dimensional fast Fourier transform (2D FFT method and local gradients (LG method, using interpolating wind directions from the European Centre for Medium-Range Weather Forecast (ECMWF reanalysis data and the Cross-Calibrated Multi-Platform (CCMP wind vector product. The sensitivities to the salt-and-pepper noise, the additive noise and the multiplicative noise are analyzed. The ILG method shows a better performance of retrieval wind directions than the other two methods.

  12. Seasonal variation of Sigma sub(Theta) with wind speed, direction and stability

    Digital Repository Service at National Institute of Oceanography (India)

    Sadhuram, Y.

    For an airport site near Visakhapatnam, India, and based on 10 years of data for the months of January, April, August and October, values of Sigma sub(Theta) are given as a function of wind speed, wind direction and Pasquill diffusion category...

  13. Optimized Permanent Magnet Generator Topologies for Direct-Drive Wind Turbines

    NARCIS (Netherlands)

    Dubois, M.R.J.

    2004-01-01

    The thesis deals with the issue of cost reduction in direct-drive generators for wind turbines. Today, the combination gearbox-medium-speed (1000-2000 rpm) induction generator largely dominates the market of MW-scale wind turbines. This is due to the lower costs of the gearbox option compared to the

  14. Design study of coated conductor direct drive wind turbine generator for small scale demonstration

    DEFF Research Database (Denmark)

    Abrahamsen, Asger Bech; Jensen, Bogi Bech

    2012-01-01

    We have investigated the properties of a superconducting direct drive generator suitable for demonstration in a small scale 11 kW wind turbine. The engineering current density of the superconducting field windings is based on properties of coated conductors wound into coils holding of the order 6...

  15. Design and numerical investigation of Savonius wind turbine with discharge flow directing capability

    DEFF Research Database (Denmark)

    Tahani, Mojtaba; Rabbani, Ali; Kasaeian, Alibakhsh

    2017-01-01

    Recently, Savonius vertical axis wind turbines due to their capabilities and positive properties have gained a significant attention. The objective of this study is to design and model a Savonius-style vertical axis wind turbine with direct discharge flow capability in order to ventilate building...

  16. Fitting a mixture of von Mises distributions in order to model data on wind direction in Peninsular Malaysia

    International Nuclear Information System (INIS)

    Masseran, N.; Razali, A.M.; Ibrahim, K.; Latif, M.T.

    2013-01-01

    Highlights: • We suggest a simple way for wind direction modeling using the mixture of von Mises distribution. • We determine the most suitable probability model for wind direction regime in Malaysia. • We provide the circular density plots to show the most prominent directions of wind blows. - Abstract: A statistical distribution for describing wind direction provides information about the wind regime at a particular location. In addition, this information complements knowledge of wind speed, which allows researchers to draw some conclusions about the energy potential of wind and aids the development of efficient wind energy generation. This study focuses on modeling the frequency distribution of wind direction, including some characteristics of wind regime that cannot be represented by a unimodal distribution. To identify the most suitable model, a finite mixture of von Mises distributions were fitted to the average hourly wind direction data for nine wind stations located in Peninsular Malaysia. The data used were from the years 2000 to 2009. The suitability of each mixture distribution was judged based on the R 2 coefficient and the histogram plot with a density line. The results showed that the finite mixture of the von Mises distribution with H number of components was the best distribution to describe the wind direction distributions in Malaysia. In addition, the circular density plots of the suitable model clearly showed the most prominent directions of wind blows than the other directions

  17. Comparison of 10 MW superconducting generator topologies for direct-drive wind turbines

    DEFF Research Database (Denmark)

    Liu, Dong; Polinder, Henk; Abrahamsen, Asger Bech

    2015-01-01

    Large wind turbines of 10 MW or higher power levels are desirable for reducing the cost of energy of offshore wind power conversion. Conventional wind generator systems will be costly if scaled up to 10 MW due to rather large size and weight. Direct drive superconducting generators have been...... proposed to address the problem with generator size, because the electrical machines with superconducting windings are capable of achieving a higher torque density of an electrical machine. However, the topology to be adopted for superconducting wind generators has not yet been settled, since the high...... magnetic field excitation allows for lightweight non-magnetic composite materials for machine cores instead of iron. A topology would probably not be a good option for an offshore wind turbine generator if it demands a far more expensive active material cost than others, even if it has other advantages...

  18. Ensemble standar deviation of wind speed and direction of the FDDA input to WRF

    Data.gov (United States)

    U.S. Environmental Protection Agency — NetCDF file of the SREF standard deviation of wind speed and direction that was used to inject variability in the FDDA input. variable U_NDG_OLD contains standard...

  19. Seasonal variation of wind direction fluctuations vs Pasquill stabilities in complex terrain

    Digital Repository Service at National Institute of Oceanography (India)

    Sadhuram, Y.; Murthy, K.P.R.V.

    The authors have studied the seasonal variation of sigma theta (the standard deviation of wind direction fluctuations) vs Pasquill stabilities over complex terrain. It is found that the values of sigma theta are quite high in the month of April...

  20. Analysis of starting resistance moment of direct drive wind turbine

    Directory of Open Access Journals (Sweden)

    He Bin

    2016-01-01

    Full Text Available Permanent magnet motor in the process of running, the permanent magnets provided the magnetic field , the core will have a strong attraction, produce the cogging torque and torque ripple, vibration and noise and other disharmony factors, seriously affect the control precision of the motor system.Therefore, in the design of permanent magnet wind turbine generator, weaken the cogging torque is very important.

  1. Analysis of Transient Phenomena Due to a Direct Lightning Strike on a Wind Energy System

    Directory of Open Access Journals (Sweden)

    João P. S. Catalão

    2012-07-01

    Full Text Available This paper is concerned with the protection of wind energy systems against the direct effects of lightning. As wind power generation undergoes rapid growth, lightning damages involving wind turbines have come to be regarded as a serious problem. Nevertheless, very few studies exist yet in Portugal regarding lightning protection of wind energy systems using numerical codes. A new case study is presented in this paper, based on a wind turbine with an interconnecting transformer, for the analysis of transient phenomena due to a direct lightning strike to the blade. Comprehensive simulation results are provided by using models of the Restructured Version of the Electro-Magnetic Transients Program (EMTP, and conclusions are duly drawn.

  2. Fault diagnosis of direct-drive wind turbine based on support vector machine

    International Nuclear Information System (INIS)

    An, X L; Jiang, D X; Li, S H; Chen, J

    2011-01-01

    A fault diagnosis method of direct-drive wind turbine based on support vector machine (SVM) and feature selection is presented. The time-domain feature parameters of main shaft vibration signal in the horizontal and vertical directions are considered in the method. Firstly, in laboratory scale five experiments of direct-drive wind turbine with normal condition, wind wheel mass imbalance fault, wind wheel aerodynamic imbalance fault, yaw fault and blade airfoil change fault are carried out. The features of five experiments are analyzed. Secondly, the sensitive time-domain feature parameters in the horizontal and vertical directions of vibration signal in the five conditions are selected and used as feature samples. By training, the mapping relation between feature parameters and fault types are established in SVM model. Finally, the performance of the proposed method is verified through experimental data. The results show that the proposed method is effective in identifying the fault of wind turbine. It has good classification ability and robustness to diagnose the fault of direct-drive wind turbine.

  3. Wind speed and direction measurement based on arc ultrasonic sensor array signal processing algorithm.

    Science.gov (United States)

    Li, Xinbo; Sun, Haixin; Gao, Wei; Shi, Yaowu; Liu, Guojun; Wu, Yue

    2016-11-01

    This article investigates a kind of method to measure the wind speed and the wind direction, which is based on arc ultrasonic sensor array and combined with array signal processing algorithm. In the proposed method, a new arc ultrasonic array structure is introduced and the array manifold is derived firstly. On this basis, the measurement of the wind speed and the wind direction is analyzed and discussed by means of the basic idea of the classic MUSIC (Multiple Signal Classification) algorithm, which achieves the measurements of the 360° wind direction with resolution of 1° and 0-60m/s wind speed with resolution of 0.1m/s. The implementation of the proposed method is elaborated through the theoretical derivation and corresponding discussion. Besides, the simulation experiments are presented to show the feasibility of the proposed method. The theoretical analysis and simulation results indicate that the proposed method has superiority on anti-noise performance and improves the wind measurement accuracy. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

  4. Multisensor satellite data integration for sea surface wind speed and direction determination

    Science.gov (United States)

    Glackin, D. L.; Pihos, G. G.; Wheelock, S. L.

    1984-01-01

    Techniques to integrate meteorological data from various satellite sensors to yield a global measure of sea surface wind speed and direction for input to the Navy's operational weather forecast models were investigated. The sensors were launched or will be launched, specifically the GOES visible and infrared imaging sensor, the Nimbus-7 SMMR, and the DMSP SSM/I instrument. An algorithm for the extrapolation to the sea surface of wind directions as derived from successive GOES cloud images was developed. This wind veering algorithm is relatively simple, accounts for the major physical variables, and seems to represent the best solution that can be found with existing data. An algorithm for the interpolation of the scattered observed data to a common geographical grid was implemented. The algorithm is based on a combination of inverse distance weighting and trend surface fitting, and is suited to combing wind data from disparate sources.

  5. Power quality issues of 3MW direct-driven PMSG wind turbine

    OpenAIRE

    Ahmed, IA; Zobaa, AF; Taylor, GA

    2015-01-01

    This paper presents power quality issues of a grid connected wind generation system with a MW-class direct-driven permanent magnet synchronous generator (PMSG). A variable speed wind turbine model was simulated and developed with the simulation tool of PSCAD/EMTDC. The model includes a wind turbine with one mass-model drive train model, a PMSG model and a full-scale voltage source back to back PWM converter. The converter controller model is employed in the dq-synchronous rotating reference f...

  6. Analyzing wind turbine directional behavior: SCADA data mining techniques for efficiency and power assessment

    International Nuclear Information System (INIS)

    Castellani, Francesco; Astolfi, Davide; Sdringola, Paolo; Proietti, Stefania; Terzi, Ludovico

    2017-01-01

    Highlights: • The directional behavior of four turbines of an onshore wind farm is investigated. • The positions of the nacelles are discretized to highlight clusterization effects. • The recurrent alignment patterns of the cluster are individuated and analyzed. • The patterns are studied by the point of view of efficiency and power output. • Significative performance deviations arise among the most frequent configurations. - Abstract: SCADA control systems are the keystone for reliable performance optimization of wind farms. Processing into knowledge the amount of information they spread is a challenging task, involving engineering, physics, statistics and computer science skills. This work deals with SCADA data analysis methods for assessing the importance of how wind turbines align in patterns to the wind direction. In particular it deals with the most common collective phenomenon causing clusters of turbines behaving as a whole, rather than as a collection of individuality: wake effects. The approach is based on the discretization of nacelle position measurements and subsequent post-processing through simple statistical methods. A cluster, severely affected by wakes, from an onshore wind farm, is selected as test case. The dominant alignment patterns of the cluster are identified and analyzed by the point of view of power output and efficiency. It is shown that non-trivial alignments with respect to the wind direction arise and important performance deviations occur among the most frequent configurations.

  7. New insights into the wind-dust relationship in sandblasting and direct aerodynamic entrainment from wind tunnel experiments

    KAUST Repository

    Parajuli, Sagar Prasad

    2016-01-22

    Numerous parameterizations have been developed for predicting wind erosion, yet the physical mechanism of dust emission is not fully understood. Sandblasting is thought to be the primary mechanism, but recent studies suggest that dust emission by direct aerodynamic entrainment can be significant under certain conditions. In this work, using wind tunnel experiments, we investigated some of the lesser understood aspects of dust emission in sandblasting and aerodynamic entrainment for three soil types, namely clay, silty clay loam, and clay loam. First, we explored the role of erodible surface roughness on dust emitted by aerodynamic entrainment. Second, we compared the emitted dust concentration in sandblasting and aerodynamic entrainment under a range of wind friction velocities. Finally, we explored the sensitivity of emitted dust particle size distribution (PSD) to soil type and wind friction velocity in these two processes. The dust concentration in aerodynamic entrainment showed strong positive correlation, no significant correlation, and weak negative correlation, for the clay, silty clay loam, and clay loam, respectively, with the erodible soil surface roughness. The dust in aerodynamic entrainment was significant constituting up to 28.3, 41.4, and 146.4% compared to sandblasting for the clay, silty clay loam, and clay loam, respectively. PSD of emitted dust was sensitive to soil type in both sandblasting and aerodynamic entrainment. PSD was sensitive to the friction velocity in aerodynamic entrainment but not in sandblasting. Our results highlight the need to consider the details of sandblasting and direct aerodynamic entrainment processes in parameterizing dust emission in global/regional climate models.

  8. Wind-direction analysis in coastal mountainous sites: An experimental study within the Gulf of Corinth, Greece

    International Nuclear Information System (INIS)

    Xydis, G.

    2012-01-01

    Highlights: ► Focus was given to the forced airflow around mountains and the effect on wind profile. ► WAsP model correlated measured and predicted wind directions in 4 coastal areas. ► The difference between simulated and measured values was always less than 8.35%. ► The clear forefront, distance from the mast and the shore influences the wind rose. - Abstract: The wind potential around several coastal areas within the Gulf of Corinth has been studied and an experimental analysis implemented accentuates the level of significance that local winds have in wind farm development and planning. The purpose of this study was to examine wind direction of coastal areas based on field measurements and correlate the results with ruggedness and distance. Four coastal mountainous areas, situated within the Gulf of Corinth, were examined and simulated results were compared to measurements aiming in explaining substantially the wind direction profile. Understanding wind flow interdependent not only from local wind, but also in the wider area of large mountains masses is of great importance for estimating wind resource in rough coastal terrain. In the present paper wind resource analysis results impose new views on the relation among masts’ horizontal distance, difference of ruggedness index, and wind direction in coastal sites.

  9. An optimal design of coreless direct-drive axial flux permanent magnet generator for wind turbine

    International Nuclear Information System (INIS)

    Ahmed, D; Ahmad, A

    2013-01-01

    Different types of generators are currently being used in wind power technology. The commonly used are induction generator (IG), doubly-fed induction generator (DFIG), electrically excited synchronous generator (EESG) and permanent magnet synchronous generator (PMSG). However, the use of PMSG is rapidly increasing because of advantages such as higher power density, better controllability and higher reliability. This paper presents an innovative design of a low-speed modular, direct-drive axial flux permanent magnet (AFPM) generator with coreless stator and rotor for a wind turbine power generation system that is developed using mathematical and analytical methods. This innovative design is implemented in MATLAB / Simulink environment using dynamic modelling techniques. The main focus of this research is to improve efficiency of the wind power generation system by investigating electromagnetic and structural features of AFPM generator during its operation in wind turbine. The design is validated by comparing its performance with standard models of existing wind power generators. The comparison results demonstrate that the proposed model for the wind power generator exhibits number of advantages such as improved efficiency with variable speed operation, higher energy yield, lighter weight and better wind power utilization.

  10. An optimal design of coreless direct-drive axial flux permanent magnet generator for wind turbine

    Science.gov (United States)

    Ahmed, D.; Ahmad, A.

    2013-06-01

    Different types of generators are currently being used in wind power technology. The commonly used are induction generator (IG), doubly-fed induction generator (DFIG), electrically excited synchronous generator (EESG) and permanent magnet synchronous generator (PMSG). However, the use of PMSG is rapidly increasing because of advantages such as higher power density, better controllability and higher reliability. This paper presents an innovative design of a low-speed modular, direct-drive axial flux permanent magnet (AFPM) generator with coreless stator and rotor for a wind turbine power generation system that is developed using mathematical and analytical methods. This innovative design is implemented in MATLAB / Simulink environment using dynamic modelling techniques. The main focus of this research is to improve efficiency of the wind power generation system by investigating electromagnetic and structural features of AFPM generator during its operation in wind turbine. The design is validated by comparing its performance with standard models of existing wind power generators. The comparison results demonstrate that the proposed model for the wind power generator exhibits number of advantages such as improved efficiency with variable speed operation, higher energy yield, lighter weight and better wind power utilization.

  11. Potential of MgB2 superconductors in direct drive generators for wind turbines

    DEFF Research Database (Denmark)

    Abrahamsen, Asger Bech; Liu, Dong; Magnusson, Niklas

    2015-01-01

    Topologies of superconducting direct drive wind turbine generators are based on a combination of superconducting wires wound into field coils, copper armature windings, steel laminates to shape the magnetic flux density and finally structural materials as support. But what is the most optimal......-Pin concept nacelle. A series of topologies are investigate by adding more iron components to the generator, such as rotor back iron, field winding pole, magnetic teeth and armature back iron. This method is used to investigate 6 topologies and to determine the optimal cost of the different topologies...... by using the current cost of 4 €/m for the MgB2 wire from Columbus Superconductors and also a possible future cost of 1 €/m if a superconducting offshore wind power capacity of 10 GW has been introduced by 2030 as suggested in a roadmap. The obtained topologies are compared to what is expected from...

  12. Design and control of a direct drive wind turbine equipped with multilevel converters

    Energy Technology Data Exchange (ETDEWEB)

    Abbes, Mohamed [LSE-ENIT, P.O Box 37, Belvedere, 1002 Tunis (Tunisia); Belhadj, Jamel [LSE-ENIT, P.O Box 37, Belvedere, 1002 Tunis (Tunisia); ESSTT, P.O. Box 56, Monfleury, 1008 Tunis (Tunisia); Ben Abdelghani Bennani, Afef [LSE-ENIT, P.O Box 37, Belvedere, 1002 Tunis (Tunisia); INSAT, P.O. Box 676, North Urban Centre, 1080 Tunis (Tunisia)

    2010-05-15

    This paper concentrates on the design and control of a three-level grid side converter (GSC) for direct drive high power wind turbines. The three-level, neutral point clamped (NPC) topology was investigated. The proposed control scheme, based on vector current control, offers very satisfying performances regarding to structure stability and grid connection requirements (GCR). In order to have an accurate evaluation of grid voltage source, two grid synchronization methods are developed and their performances are compared. The GSC performances are evaluated under both normal and grid fault conditions. Simulation results show that stability is maintained during voltage dips and that the proposed direct drive wind turbine satisfies completely GCR. (author)

  13. Analysis of vertical wind direction and speed gradients for data from the met. mast at Høvsøre

    DEFF Research Database (Denmark)

    Cariou, Nicolas; Wagner, Rozenn; Gottschall, Julia

    The task of this project has been to study the vertical gradient of the wind direction from experimental data obtained with different measurement instruments at the Høvsøre test site, located at the west coast of Denmark. The major part of the study was based on data measured by wind vanes mounted...... at a meteorological (met.) mast. These measurements enabled us to make an analysis of the variation of the direction with altitude, i.e. the wind direction shear. For this purpose, four years of wind direction measurements at two heights (60 m and 100 m) were analysed with special respect to the diurnal and seasonal...... variations of the direction gradient. The location of the test site close to the sea allowed for an investigation of specific trends for offshore and onshore winds, dependent on the considered wind direction sector. Furthermore, a comparison to lidar measurements showed the existence of an offset between...

  14. Wind direction over the ocean determined by an airborne, imaging, polarimetric radiometer system

    DEFF Research Database (Denmark)

    Laursen, Brian; Skou, Niels

    2001-01-01

    The speed and direction of winds over the ocean can be determined by polarimetric radiometers. This has been established by theoretical work and demonstrated experimentally using airborne radiometers carrying out circle flights and thus measuring the full 360° azimuthal response from the sea surf...

  15. Design considerations for permanent magnet direct drive generators for wind energy applications

    NARCIS (Netherlands)

    Jassal, A.K.; Polinder, H.; Damen, M.E.C.; Versteegh, K.

    2012-01-01

    Permanent Magnet Direct Drive (PMDD) generators offer very high force density, high efficiency and low number of components. Due to these advantages, PMDD generators are getting popular in the wind energy industry especially for offshore application. Presence of permanent magnets gives magnetic

  16. Design study of a 10 MW MgB2 superconductor direct drive wind turbine generator

    NARCIS (Netherlands)

    Abrahamsen, A.B.; Magnusson, N.; Liu, D.; Stehouwer, E.; Hendriks, B.; Polinder, H.

    2014-01-01

    A superconducting direct drive generator based on field windings of MgB2 superconducting tape is proposed as a solution by mounting the generator in front of the blades using a king-pin nacelle design for offshore turbines with power ratings larger than 10 MW as investigated in the INNWIND.EU

  17. Design study of a 10 MW MgB2 superconductor direct drive wind turbine generator

    DEFF Research Database (Denmark)

    Abrahamsen, Asger Bech; Magnusson, Niklas; Liu, Dong

    2014-01-01

    A superconducting direct drive generator based on field windings of MgB2 superconducting tape is proposed as a solution by mounting the generator in front of the blades using a king-pin nacelle design for offshore turbines with power ratings larger than 10 MW as investigated in the INNWIND.EU pro...

  18. Short Communication The effect of wind direction on flying fish counts

    African Journals Online (AJOL)

    Flying fish and squid flushed by a ship's passage are easy to count, but the value of such data is compromised by uncertainty regarding the proportion of individuals flushed. Wind direction relative to the ship's course plays an important role in determining this proportion, with on average 6 times (range 2.5–10.8) more fish ...

  19. The Wind Lost its Direction | Ezenwa-Ohaeto | UJAH: Unizik Journal ...

    African Journals Online (AJOL)

    UJAH: Unizik Journal of Arts and Humanities. Journal Home · ABOUT · Advanced Search · Current Issue · Archives · Journal Home > Special Edition 2011 >. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register. The Wind Lost its Direction. C Ezenwa-Ohaeto. Abstract.

  20. Design of Transverse Flux Permanent Magnet Machines for Large Direct-Drive Wind Turbines

    NARCIS (Netherlands)

    Bang, D.

    2010-01-01

    In order to maximize the energy harnessed, to minimize the cost, to improve the power quality and to ensure safety together with the growth of the size, various wind turbine concepts have been developed during last three decades. Different generator systems such as geared and direct-drive generator

  1. Wind Stress Variability Directly Measured at a Tidal Inlet from a Mobile Vessel

    Science.gov (United States)

    Ortiz-Suslow, D. G.; Haus, B. K.; Laxague, N.; Williams, N. J.; Graber, H. C.

    2014-12-01

    Tidal inlets are characterized by a dynamic coupling of waves, currents, wind, and topography and to better understand these processes the Riverine and Estuarine Transport (RIVET) experiment was conducted during the month of May 2012 at New River Inlet, North Carolina. As a part of that effort, the Surface Physics Experimental Catamaran (SPEC) was outfitted with a suite of concurrently sampled atmospheric and oceanographic sensors. These included a meteorological mast capable of measuring the air-sea momentum flux, paired subsurface ADV's, a downward looking ADCP, and a bow-mounted wave-staff array. Using a mobile platform enabled capturing the fine-scale dynamical features across this highly sheared zone, without compromising spatial or temporal resolution. The SPEC was deployed, in part, to make direct wind stress measurements and the eddy covariance method was used to calculate the 10 m neutral drag coefficients from the observed wind shear velocities. In general, for any given wind speed, measured drag coefficients were about 2.5 times greater than those derived from bulk relations (e.g. Smith, 1988). Observations of the wind stress angle show significant wind stress steering, up to about 70o off the mean wind direction, within 2 km off-shore of the inlet mouth. The causes for the departure of these observations from conventional open ocean results remains under investigation, although it is highly likely that these findings highlight processes unique to coastal waters that are not regarded in the well-established algorithms (e.g. depth-limited wave breaking and wave-current interactions). Preliminary results from the second installment in the RIVET campaign, which took place at the Mouth of the Columbia River during the spring of 2013, will also be shown.

  2. Microphone directionality, pre-emphasis filter, and wind noise in cochlear implants.

    Science.gov (United States)

    Chung, King; McKibben, Nicholas

    2011-10-01

    Wind noise can be a nuisance or a debilitating masker for cochlear implant users in outdoor environments. Previous studies indicated that wind noise at the microphone/hearing aid output had high levels of low-frequency energy and the amount of noise generated is related to the microphone directionality. Currently, cochlear implants only offer either directional microphones or omnidirectional microphones for users at-large. As all cochlear implants utilize pre-emphasis filters to reduce low-frequency energy before the signal is encoded, effective wind noise reduction algorithms for hearing aids might not be applicable for cochlear implants. The purposes of this study were to investigate the effect of microphone directionality on speech recognition and perceived sound quality of cochlear implant users in wind noise and to derive effective wind noise reduction strategies for cochlear implants. A repeated-measure design was used to examine the effects of spectral and temporal masking created by wind noise recorded through directional and omnidirectional microphones and the effects of pre-emphasis filters on cochlear implant performance. A digital hearing aid was programmed to have linear amplification and relatively flat in-situ frequency responses for the directional and omnidirectional modes. The hearing aid output was then recorded from 0 to 360° at flow velocities of 4.5 and 13.5 m/sec in a quiet wind tunnel. Sixteen postlingually deafened adult cochlear implant listeners who reported to be able to communicate on the phone with friends and family without text messages participated in the study. Cochlear implant users listened to speech in wind noise recorded at locations that the directional and omnidirectional microphones yielded the lowest noise levels. Cochlear implant listeners repeated the sentences and rated the sound quality of the testing materials. Spectral and temporal characteristics of flow noise, as well as speech and/or noise characteristics before

  3. Relationships between airborne pollen grains, wind direction and land cover using GIS and circular statistics.

    Science.gov (United States)

    Maya-Manzano, J M; Sadyś, M; Tormo-Molina, R; Fernández-Rodríguez, S; Oteros, J; Silva-Palacios, I; Gonzalo-Garijo, A

    2017-04-15

    Airborne bio-aerosol content (mainly pollen and spores) depends on the surrounding vegetation and weather conditions, particularly wind direction. In order to understand this issue, maps of the main land cover in influence areas of 10km in radius surrounding pollen traps were created. Atmospheric content of the most abundant 14 pollen types was analysed in relation to the predominant wind directions measured in three localities of SW of Iberian Peninsula, from March 2011 to March 2014. Three Hirst type traps were used for aerobiological monitoring. The surface area for each land cover category was calculated and wind direction analysis was approached by using circular statistics. This method could be helpful for estimating the potential risk of exposure to various pollen types. Thus, the main land cover was different for each monitoring location, being irrigated crops, pastures and hardwood forests the main categories among 11 types described. Comparison of the pollen content with the predominant winds and land cover shows that the atmospheric pollen concentration is related to some source areas identified in the inventory. The study found that some pollen types (e.g. Plantago, Fraxinus-Phillyrea, Alnus) come from local sources but other pollen types (e.g. Quercus) are mostly coming from longer distances. As main conclusions, airborne particle concentrations can be effectively split by addressing wind with circular statistics. By combining circular statistics and GIS method with aerobiological data, we have created a useful tool for understanding pollen origin. Some pollen loads can be explained by immediate surrounding landscape and observed wind patterns for most of the time. However, other factors like medium or long-distance transport or even pollen trap location within a city, may occasionally affect the pollen load recorded using an air sampler. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Directionality Effects of Aligned Wind and Wave Loads on a Y-Shape Semi-Submersible Floating Wind Turbine under Rated Operational Conditions

    Directory of Open Access Journals (Sweden)

    Shengtao Zhou

    2017-12-01

    Full Text Available The Y-shape (triangular semi-submersible foundation has been adopted by most of the built full-scale floating wind turbines, such as Windfloat, Fukushima Mirai and Shimpuu. Considering the non-fully-symmetrical shape and met-ocean condition, the foundation laying angle relative to wind/wave directions will not only influence the downtime and power efficiency of the floating turbine, but also the strength and fatigue safety of the whole structure. However, the dynamic responses induced by various aligned wind and wave load directions have scarcely been investigated comparatively before. In our study, the directionality effects are investigated by means of combined wind and wave tests and coupled multi-body simulations. By comparing the measured data in three load directions, it is found that the differences of platform motions are mainly derived from the wave loads and larger pitch motion can always be observed in one of the directions. To make certain the mechanism underlying the observed phenomena, a coupled multi-body dynamic model of the floating wind turbine is established and validated. The numerical results demonstrate that the second-order hydrodynamic forces contribute greatly to the directionality distinctions for surge and pitch, and the first-order hydrodynamic forces determine the variations of tower base bending moments and nacelle accelerations. These findings indicate the directionality effects should be predetermined comprehensively before installation at sea, which is important for the operation and maintenance of the Y-shape floating wind turbines.

  5. Is the Economic Crisis Challenging the Prevailing Gender Regime?

    DEFF Research Database (Denmark)

    Leschke, Janine; Jepsen, Maria

    2014-01-01

    This paper addresses the question of whether the current economic and financial crisis is challenging the prevailing gender-equality model in four European countries: Denmark, Germany, Slovakia, and the United Kingdom. After situating the countries in relation to the underlying gender regime...... and analysing the corresponding position of women and men in paid and unpaid work, the paper contains an in-depth discussion of the short- and medium-term policy responses to the crisis. Our analysis shows that independent of the prevailing gender regime, scant public attention has been directed to gender...

  6. Conventional and novel control designs for direct driven PMSG wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shuhui; Haskew, Timothy A.; Xu, Ling [Department of Electrical and Computer Engineering, The University of Alabama, 317 Houser Hall, Tuscaloosa, AL 35487 (United States)

    2010-03-15

    With the advance of power electronic technology, direct driven permanent magnet synchronous generators (PMSG) have increasingly drawn interests to wind turbine manufactures. This paper studies and compares conventional and a novel control designs for a direct driven PMSG wind turbine. The paper presents transient and steady-state models of a PMSG system in a d-q reference frame. Then, general PMSG characteristics are investigated in the rotor-flux-oriented frame. A shortage of conventional control mechanisms is studied analytically and through computer simulation. A novel direct-current based d-q vector control technique is proposed by integrating fuzzy, adaptive and traditional PID control technologies in an optimal control configuration. Comparison study demonstrates that the proposed control approach, having superior performance in various aspects, is effective not only in achieving desired PMSG control objectives but also in improving the optimal performance of the overall system. (author)

  7. Combining Ordinary Kriging with wind directions to identify sources of industrial odors in Portland, Oregon.

    Science.gov (United States)

    Eckmann, Ted C; Wright, Samantha G; Simpson, Logan K; Walker, Joe L; Kolmes, Steven A; Houck, James E; Velasquez, Sandra C

    2018-01-01

    This study combines Ordinary Kriging, odor monitoring, and wind direction data to demonstrate how these elements can be applied to identify the source of an industrial odor. The specific case study used as an example of how to address this issue was the University Park neighborhood of Portland, Oregon (USA) where residents frequently complain about industrial odors, and suspect the main source to be a nearby Daimler Trucks North America LLC manufacturing plant. We collected 19,665 odor observations plus 105,120 wind measurements, using an automated weather station to measure winds in the area at five-minute intervals, logging continuously from December 2014 through November 2015, while we also measured odors at 19 locations, three times per day, using methods from the American Society of the International Association for Testing and Materials. Our results quantify how winds vary with season and time of day when industrial odors were observed versus when they were not observed, while also mapping spatiotemporal patterns in these odors using Ordinary Kriging. Our analyses show that industrial odors were detected most frequently to the northwest of the Daimler plant, mostly when winds blew from the southeast, suggesting Daimler's facility is a likely source for much of this odor.

  8. Wind-direction analysis in coastal mountainous sites: An experimental study within the Gulf of Corinth, Greece

    DEFF Research Database (Denmark)

    Xydis, George

    2012-01-01

    areas based on field measurements and correlate the results with ruggedness and distance. Four coastal mountainous areas, situated within the Gulf of Corinth, were examined and simulated results were compared to measurements aiming in explaining substantially the wind direction profile. Understanding...... wind flow interdependent not only from local wind, but also in the wider area of large mountains masses is of great importance for estimating wind resource in rough coastal terrain. In the present paper wind resource analysis results impose new views on the relation among masts’ horizontal distance...

  9. On the Feasibility of Tracking the Monsoon History by Using Ancient Wind Direction Records

    Science.gov (United States)

    Gallego, D.; Ribera, P.; Peña-Ortiz, C.; Vega, I.; Gómez, F. D. P.; Ordoñez-Perez, P.; Garcia-Hererra, R.

    2015-12-01

    In this work, we use old wind direction records to reconstruct indices for the West African Monsoon (WAM) and the Indian Summer Monsoon (ISM). Since centuries ago, ships departing from the naval European powers circumnavigated Africa in their route to the Far East. Most of these ships took high-quality observations preserved in logbooks. We show that wind direction observations taken aboard ships can be used to track the seasonal wind reversal typical of monsoonal circulations. The persistence of the SW winds in the 20W-17W and 7N-13N region is highly correlated with the WAM strength and Sahel's precipitation. It has been possible to build a WAM index back to the 19th Century. Our results show that in the Sahel, the second half of the 19thCentury was significantly wetter than present day. The relation of the WAM with the ENSO cycle, and the Atlantic Multidecadal Oscillation was low and instable from the 1840s to the 1970s, when they abruptly suffered an unprecedented reinforcement which last up to the present day. The persistence of the SSW wind in the 60E-80E and 8N-12N area has been used to track the ISM onset since the 1880s. We found evidences of later than average onset dates during the 1900-1925 and 1970-1990 periods and earlier than average onset between 1940 and 1965. A significant relation between the ISM onset and the PDO restricted to shifts from negative to positive PDO phases has been found. The most significant contribution of our study is the fact that we have shown that it is possible to build consistent monsoon indices of instrumental character using solely direct observations of wind direction. Our indices have been generated by using data currently available in the ICOADS 2.5 database, but a large amount of wind observations for periods previous to the 20thcentury still remain not explored in thousands of logbooks preserved in British archives. The interest of unveil these data to track the monsoons for more than 200 -or even 300 years- it is

  10. Effects of Strand Lay Direction and Crossing Angle on Tribological Behavior of Winding Hoist Rope

    Directory of Open Access Journals (Sweden)

    Xiang-dong Chang

    2017-06-01

    Full Text Available Friction and wear behavior exists between hoisting ropes that are wound around the drums of a multi-layer winding hoist. It decreases the service life of ropes and threatens mine safety. In this research, a series of experiments were conducted using a self-made test rig to study the effects of the strand lay direction and crossing angle on the winding rope’s tribological behavior. Results show that the friction coefficient in the steady-state period shows a decreasing tendency with an increase of the crossing angle in both cross directions, but the variation range is different under different cross directions. Using thermal imaging, the high temperature regions always distribute along the strand lay direction in the gap between adjacent strands, as the cross direction is the same with the strand lay direction (right cross contact. Additionally, the temperature rise in the steady-state increases with the increase of the crossing angle in both cross directions. The differences of the wear scar morphology are obvious under different cross directions, especially for the large crossing angle tests. In the case of right cross, the variation range of wear mass loss is larger than that in left cross. The damage that forms on the wear surface is mainly ploughing, pits, plastic deformation, and fatigue fracture. The major wear mechanisms are adhesive wear, and abrasive and fatigue wear.

  11. Effects of Strand Lay Direction and Crossing Angle on Tribological Behavior of Winding Hoist Rope.

    Science.gov (United States)

    Chang, Xiang-Dong; Peng, Yu-Xing; Zhu, Zhen-Cai; Gong, Xian-Sheng; Yu, Zhang-Fa; Mi, Zhen-Tao; Xu, Chun-Ming

    2017-06-09

    Friction and wear behavior exists between hoisting ropes that are wound around the drums of a multi-layer winding hoist. It decreases the service life of ropes and threatens mine safety. In this research, a series of experiments were conducted using a self-made test rig to study the effects of the strand lay direction and crossing angle on the winding rope's tribological behavior. Results show that the friction coefficient in the steady-state period shows a decreasing tendency with an increase of the crossing angle in both cross directions, but the variation range is different under different cross directions. Using thermal imaging, the high temperature regions always distribute along the strand lay direction in the gap between adjacent strands, as the cross direction is the same with the strand lay direction (right cross contact). Additionally, the temperature rise in the steady-state increases with the increase of the crossing angle in both cross directions. The differences of the wear scar morphology are obvious under different cross directions, especially for the large crossing angle tests. In the case of right cross, the variation range of wear mass loss is larger than that in left cross. The damage that forms on the wear surface is mainly ploughing, pits, plastic deformation, and fatigue fracture. The major wear mechanisms are adhesive wear, and abrasive and fatigue wear.

  12. Assimilation of wind speed and direction observations: results from real observation experiments

    Directory of Open Access Journals (Sweden)

    Feng Gao

    2015-06-01

    Full Text Available The assimilation of wind observations in the form of speed and direction (asm_sd by the Weather Research and Forecasting Model Data Assimilation System (WRFDA was performed using real data and employing a series of cycling assimilation experiments for a 2-week period, as a follow-up for an idealised post hoc assimilation experiment. The satellite-derived Atmospheric Motion Vectors (AMV and surface dataset in Meteorological Assimilation Data Ingest System (MADIS were assimilated. This new method takes into account the observation errors of both wind speed (spd and direction (dir, and WRFDA background quality control (BKG-QC influences the choice of wind observations, due to data conversions between (u,v and (spd, dir. The impacts of BKG-QC, as well as the new method, on the wind analysis were analysed separately. Because the dir observational errors produced by different platforms are not known or tuned well in WRFDA, a practical method, which uses similar assimilation weights in comparative trials, was employed to estimate the spd and dir observation errors. The asm_sd produces positive impacts on analyses and short-range forecasts of spd and dir with smaller root-mean-square errors than the u,v-based system. The bias of spd analysis decreases by 54.8%. These improvements result partly from BKG-QC screening of spd and dir observations in a direct way, but mainly from the independent impact of spd (dir data assimilation on spd (dir analysis, which is the primary distinction from the standard WRFDA method. The potential impacts of asm_sd on precipitation forecasts were evaluated. Results demonstrate that the asm_sd is able to indirectly improve the precipitation forecasts by improving the prediction accuracies of key wind-related factors leading to precipitation (e.g. warm moist advection and frontogenesis.

  13. Directional short wind wave spectra derived from the sea surface photography

    Science.gov (United States)

    Dulov, Vladimir; Yurovskaya, Maria; Chapron, Bertrand; Kudryavtsev, Vladimir

    2014-05-01

    New field measurements of 2-D wave number short wind wave spectra in the wavelength range from few millimeters to few decimeters are reported and discussed. The measurement method proposed by [Kosnik and Dulov, 2011] is based on stereophotography and image brightness contrast processing. The method strongly builds on the brightness cross-spectral analysis to reduce the noise within this short wave gravity and capillary range. Field measurements of wind wave spectra are still rare, and the reported data thus provide valuable information to bring new evidences on the 2-D spectral distribution of short wind waves in the wavelength range from decimeters to millimeters. As found, the folded spectra of decimeter waves are very weakly dependent on the wind speed and its direction. Wind speed and direction sensitivity only starts to appear in the short wavelength range, more precisely in the vicinity of the wave number 100 rad/m, where the wind exponent grows from 0.5 to 1.5-2.5 at 800 rad/m, and angular anisotropy parameter introduced by [Elfouhaily et al., 1997] amounts the value of 0.5. These aspects are consistent with other previously reported optical and radar data. For the latter, we solely extracted the polarization sensitivity to best isolate the contribution associated to the wave saturation spectrum around the Bragg resonant wave number. For the former, mean-squared slope statistics were used to assess the integrated shortscale directional spectral properties. As revealed, observed direction spectral distributions are significantly different from those previously suggested [Elfouhaily et al., 1997; Kudryavtsev et al., 2003, 2005]. On the basis of these new in situ measurements, we then propose to revise the semiempirical analytical model of short wind wave spectra developed by [Kudryavtsev et al., 2003, 2005]. In this model the key parameter is exponent n governing the nonlinear dissipation rate as D ~ Bn+1, where B is saturation spectrum. Accordingly, new

  14. Assessing spring direct mortality to avifauna from wind energy facilities in the Dakotas

    Science.gov (United States)

    Graff, Brianna J.; Jenks, Jonathan A.; Stafford, Joshua D.; Jensen, Kent C.; Grovenburg, Troy W.

    2016-01-01

    The Northern Great Plains (NGP) contains much of the remaining temperate grasslands, an ecosystem that is one of the most converted and least protected in the world. Within the NGP, the Prairie Pothole Region (PPR) provides important habitat for >50% of North America's breeding waterfowl and many species of shorebirds, waterbirds, and grassland songbirds. This region also has high wind energy potential, but the effects of wind energy developments on migratory and resident bird and bat populations in the NGP remains understudied. This is troubling considering >2,200 wind turbines are actively generating power in the region and numerous wind energy projects have been proposed for development in the future. Our objectives were to estimate avian and bat fatality rates for wind turbines situated in cropland- and grassland-dominated landscapes, document species at high risk to direct mortality, and assess the influence of habitat variables on waterfowl mortality at 2 wind farms in the NGP. From 10 March to 7 June 2013–2014, we completed 2,398 searches around turbines for carcasses at the Tatanka Wind Farm (TAWF) and the Edgeley-Kulm Wind Farm (EKWF) in South Dakota and North Dakota. During spring, we found 92 turbine-related mortalities comprising 33 species and documented a greater diversity of species (n = 30) killed at TAWF (predominately grassland) than at EKWF (n = 9; predominately agricultural fields). After accounting for detection rates, we estimated spring mortality of 1.86 (SE = 0.22) deaths/megawatt (MW) at TAWF and 2.55 (SE = 0.51) deaths/MW at EKWF. Waterfowl spring (Mar–Jun) fatality rates were 0.79 (SE = 0.11) and 0.91 (SE = 0.10) deaths/MW at TAWF and EKWF, respectively. Our results suggest that future wind facility siting decisions consider avoiding grassland habitats and locate turbines in pre-existing fragmented and converted habitat outside of high densities of breeding waterfowl and major migration corridors.

  15. Design Considerations of a Transverse Flux Machine for Direct-Drive Wind Turbine Applications

    Energy Technology Data Exchange (ETDEWEB)

    Husain, Tausif; Hasan, Iftekhar; Sozer, Yilmaz; Husain, Iqbal; Muljadi, Eduard

    2018-01-01

    This paper presents the design considerations of a double-sided transverse flux machine (TFM) for direct-drive wind turbine applications. The proposed TFM has a modular structure with quasi-U stator cores and toroidal ring windings. The rotor is constructed with ferrite magnets in a flux-concentrating setup to achieve high air gap flux density. Pole number selection is critical in the design process of a TFM as it affects both the torque density and power factor under fixed magnetic and changing electrical loading. Several key design ratios are introduced to facilitate the initial design procedure. The effect of pole shaping on back-EMF and inductance is also analyzed. These investigations provide guidance toward the required design of a TFM for direct-drive applications. The analyses are carried out using analytical and three-dimensional finite element analysis (FEA). A proof-of-concept prototype was developed to experimentally validate the FEA results.

  16. Effect of Side Wind on the Directional Stability and Aerodynamics of a Hybrid Buoyant Aircraft

    Directory of Open Access Journals (Sweden)

    Haque Anwar U

    2016-01-01

    Full Text Available Directional stability characteristics explain the capabilities of a hybrid buoyant aircraft’s performance against the side wind, which induces flow separation that is chaotic in nature and may lead to oscillations of the aerodynamic surfaces. A numerical study is carried out to estimate the effect of side wind. The boundary conditions for the computational domain are set to velocity inlet and pressure outlet. Due to the incompressible flow at the cruise velocity, the density is taken to be constant. For these steady state simulations, the time is discretized in first order implicit and the SIMPLE scheme is employed for pressure velocity coupling alongwith k-ω SST model. Based on the results obtained so far, it is concluded that voluminous hybrid lifting fuselage is the major cause of directional.

  17. Wind direction correlated measurements of radon and radon progeny in atmosphere: a method for radon source identification

    Energy Technology Data Exchange (ETDEWEB)

    Akber, R.A.; Pfitzner, J.; Johnston, A. [Environmental Research Inst. of the Supervising Scientist, Jabiru, NT (Australia)

    1994-12-31

    This paper describes the basic principles and methodology of a wind direction correlated measurement technique which is used to distinguish the mine-related and background components of radon and radon progeny concentrations in the vicinity of the ERA Ranger Uranium Mine. Simultaneous measurements of atmospheric radon and radon progeny concentrations and wind speed and direction were conducted using automatic sampling stations. The data were recorded as a time series of half hourly averages and grouped into sixteen 22.5 degrees wind sectors. The sampling interval and the wind sector width were chosen considering wind direction variability ({sigma} {sub {theta}}) over the sampling time interval. The data were then analysed for radon and radon progeny concentrations in each wind sector. Information about the wind frequency wind speed seasonal and diurnal variations in wind direction and radon concentrations was required for proper data analysis and interpretation of results. A comparison with model-based estimates for an identical time period shows agreement within about a factor of two between the two methods. 15 refs., 1 tab., 5 figs.

  18. Wind direction correlated measurements of radon and radon progeny in atmosphere: a method for radon source identification

    International Nuclear Information System (INIS)

    Akber, R.A.; Pfitzner, J.; Johnston, A.

    1994-01-01

    This paper describes the basic principles and methodology of a wind direction correlated measurement technique which is used to distinguish the mine-related and background components of radon and radon progeny concentrations in the vicinity of the ERA Ranger Uranium Mine. Simultaneous measurements of atmospheric radon and radon progeny concentrations and wind speed and direction were conducted using automatic sampling stations. The data were recorded as a time series of half hourly averages and grouped into sixteen 22.5 degrees wind sectors. The sampling interval and the wind sector width were chosen considering wind direction variability (σ θ ) over the sampling time interval. The data were then analysed for radon and radon progeny concentrations in each wind sector. Information about the wind frequency wind speed seasonal and diurnal variations in wind direction and radon concentrations was required for proper data analysis and interpretation of results. A comparison with model-based estimates for an identical time period shows agreement within about a factor of two between the two methods. 15 refs., 1 tab., 5 figs

  19. Design study of a 10 MW MgB2 superconductor direct drive wind turbine generator

    DEFF Research Database (Denmark)

    Abrahamsen, Asger Bech; Magnusson, Niklas; Liu, Dong

    2014-01-01

    A design study of a 10 MW direct drive wind turbine generator based on MgB2 superconducting wires is presented and the cost of the active materials of the generator is estimated to be between 226 €/kW and 84 €/kw, which is lower than the threshold values of 300 €/kW of the INNWIND.EU project. A n...

  20. Dynamical response of the magnetotail to changes of the solar wind direction: an MHD modeling perspective

    Directory of Open Access Journals (Sweden)

    V. A. Sergeev

    2008-08-01

    Full Text Available We performed global MHD simulations to investigate the magnetotail response to the solar wind directional changes (Vz-variations. These changes, although small, cause significant variations of the neutral sheet shape and location even in the near and middle tail regions. They display a complicated temporal response, in which ~60 to 80% of the final shift of the neutral sheet in Z direction occurs within first 10–15 min (less for faster solar wind, whereas a much longer time (exceeding half hour is required to reach a new equilibrium. The asymptotic equilibrium shape of the simulated neutral sheet is consistent with predictions of Tsyganenko-Fairfield (2004 empirical model. To visualize a physical origin of the north-south tail motion we compared the values of the total pressure in the northern and southern tail lobes and found a considerable difference (10–15% for only 6° change of the solar wind direction used in the simulation. That difference builds up during the passage of the solar wind directional discontinuity and is responsible for the vertical shift of the neutral sheet, although some pressure difference remains in the near tail even near the new equilibrium. Surprisingly, at a given tailward distance, the response was found to be first initiated in the tail center (the "leader effect", rather than near the flanks, which can be explained by the wave propagation in the tail, and which may have interesting implications for the substorm triggering studies. The present results have serious implications for the data-based modeling, as they place constraints on the accuracy of tail magnetic configurations to be derived for specific events using data of multi-spacecraft missions, e.g. such as THEMIS.

  1. Direct monitoring of wind-induced pressure-pumping on gas transport in soil

    Science.gov (United States)

    Laemmel, Thomas; Mohr, Manuel; Schindler, Dirk; Schack-Kirchner, Helmer; Maier, Martin

    2017-04-01

    Gas exchange between soil and atmosphere is important for the biogeochemistry of soils and is commonly assumed to be governed by molecular diffusion. Yet a few previous field studies identified other gas transport processes such as wind-induced pressure-pumping to enhance soil-atmosphere fluxes significantly. However, since these wind-induced non-diffusive gas transport processes in soil often occur intermittently, the quantification of their contribution to soil gas emissions is challenging. To quantify the effects of wind-induced pressure-pumping on soil gas transport, we developed a method for in situ monitoring of soil gas transport. The method includes the use of Helium (He) as a tracer gas which was continuously injected into the soil. The resulting He steady-state concentration profile was monitored. Gas transport parameters of the soil were inversely modelled. We used our method during a field campaign in a well-aerated forest soil over three months. During periods of low wind speed, soil gas transport was modelled assuming diffusion as transport process. During periods of high wind speed, the previously steady diffusive He concentration profile showed temporary concentration decreases in the topsoil, indicating an increase of the effective gas transport rate in the topsoil up to 30%. The enhancement of effective topsoil soil gas diffusivity resulted from wind-induced air pressure fluctuations which are referred to as pressure-pumping. These air pressure fluctuations had frequencies between 0.1 and 0.01 Hz and amplitudes up to 10 Pa and occurred at above-canopy wind speeds greater than 5 m s-1. We could show the importance of the enhancement of the gas transport rate in relation with the wind intensity and corresponding air pressure fluctuations characteristics. We directly detected and quantified the pressure-pumping effect on gas transport in soil in a field study for the first time, and could thus validate and underpin the importance of this non

  2. Application of Surface Protective Coating to Enhance Environment-Withstanding Property of the MEMS 2D Wind Direction and Wind Speed Sensor

    Science.gov (United States)

    Shin, Kyu-Sik; Lee, Dae-Sung; Song, Sang-Woo; Jung, Jae Pil

    2017-01-01

    In this study, a microelectromechanical system (MEMS) two-dimensional (2D) wind direction and wind speed sensor consisting of a square heating source and four thermopiles was manufactured using the heat detection method. The heating source and thermopiles of the manufactured sensor must be exposed to air to detect wind speed and wind direction. Therefore, there are concerns that the sensor could be contaminated by deposition or adhesion of dust, sandy dust, snow, rain, and so forth, in the air, and that the membrane may be damaged by physical shock. Hence, there was a need to protect the heating source, thermopiles, and the membrane from environmental and physical shock. The upper protective coating to protect both the heating source and thermopiles and the lower protective coating to protect the membrane were formed by using high-molecular substances such as SU-8, Teflon and polyimide (PI). The sensor characteristics with the applied protective coatings were evaluated. PMID:28925942

  3. Application of Surface Protective Coating to Enhance Environment-Withstanding Property of the MEMS 2D Wind Direction and Wind Speed Sensor.

    Science.gov (United States)

    Shin, Kyu-Sik; Lee, Dae-Sung; Song, Sang-Woo; Jung, Jae Pil

    2017-09-19

    In this study, a microelectromechanical system (MEMS) two-dimensional (2D) wind direction and wind speed sensor consisting of a square heating source and four thermopiles was manufactured using the heat detection method. The heating source and thermopiles of the manufactured sensor must be exposed to air to detect wind speed and wind direction. Therefore, there are concerns that the sensor could be contaminated by deposition or adhesion of dust, sandy dust, snow, rain, and so forth, in the air, and that the membrane may be damaged by physical shock. Hence, there was a need to protect the heating source, thermopiles, and the membrane from environmental and physical shock. The upper protective coating to protect both the heating source and thermopiles and the lower protective coating to protect the membrane were formed by using high-molecular substances such as SU-8, Teflon and polyimide (PI). The sensor characteristics with the applied protective coatings were evaluated.

  4. Effect of fall wind on wind power generation; Furyoku hatsuden ni okeru dashikaze no koka

    Energy Technology Data Exchange (ETDEWEB)

    Nagai, H. [Nihon University, Tokyo (Japan)

    1997-11-25

    Wind conditions in Arakawa Town, Niigata Prefecture, were surveyed by anemometers and anemoscopes installed at 3 different points, and the data are analyzed to develop the prediction model for investigating possibility of introduction of wind mills there. Outlined herein is power generated by fall wind by comparing predicted power availability with the actual results. In order to investigate possibility of power generation by fall wind, the wind conditions and power availability are simulated using the observed wind condition data. Predicted wind velocity involves a large error at a point where frequency of prevailing wind direction is high, and direction in which average wind velocity is high coincides with direction in which land is slanted at a high slope. Fall wind occurs locally for geographical reasons. Location of the wind mill must be carefully considered, because it is complex, although potentially gives a larger quantity of power. A wind mill of 400kW can produce power of around 600MWh annually, when it is located at the suited site confirmed by the wind condition analysis results. 6 refs., 5 figs., 6 tabs.

  5. Estimates of oceanic surface wind speed and direction using orthogonal beam scatterometer measurements and comparison of recent sea scattering theories

    Science.gov (United States)

    Moore, R. K.; Fung, A. K.; Dome, G. J.; Birrer, I. J.

    1978-01-01

    The wind direction properties of radar backscatter from the sea were empirically modelled using a cosine Fourier series through the 4th harmonic in wind direction (referenced to upwind). A comparison with 1975 JONSWAP (Joint North Sea Wave Project) scatterometer data, at incidence angles of 40 and 65, indicates that effects to third and fourth harmonics are negligible. Another important result is that the Fourier coefficients through the second harmonic are related to wind speed by a power law expression. A technique is also proposed to estimate the wind speed and direction over the ocean from two orthogonal scattering measurements. A comparison between two different types of sea scatter theories, one type presented by the work of Wright and the other by that of Chan and Fung, was made with recent scatterometer measurements. It demonstrates that a complete scattering model must include some provisions for the anisotropic characteristics of the sea scatter, and use a sea spectrum which depends upon wind speed.

  6. Modal analysis of a grid-connected direct-drive permanent magnet synchronous generator wind turbine system

    DEFF Research Database (Denmark)

    Tan, Jin; Wang, Xiao Ru; Chen, Zhe

    2013-01-01

    In order to study the stability of a grid-connected direct-drive permanent magnet synchronous generator (PMSG) wind turbine systems, this paper presents the modal analysis of a PMSG wind turbine system. A PMSG model suitable for small signal stability analysis is presented. The modal properties...

  7. A Lightweight, Direct-Drive, Fully Superconducting Generator for Large Wind Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Meinke, Rainer [Advanced Magnet Lab, Palm Bay, FL (United States); Morrison, Darrell [Emerson Inc., St. Louis, MO (United States); Prince, Vernon Gregory [Advanced Magnet Lab, Palm Bay, FL (United States)

    2014-12-31

    The current trend in the offshore wind turbine industry favors direct-drive generators based on permanent magnets, as they allow for a simple and reliable drivetrain without a gearbox. These generators, however, do not scale very well to high power levels beneficial for offshore wind, and their use in wind turbines over 6 MW is questionable in terms of mass and economic feasibility. Moreover, rare earth materials composing the permanent magnets are becoming less available, more costly and potentially unavailable in the foreseeable future. A stated goal of the DOE is a critical materials strategy that pursues the development of substitute materials and technology for rare earth materials to improve supply chain flexibility and meet the needs of the clean energy economy.Therefore, alternative solutions are needed, in terms of both favorable up-scaling and minimizing or eliminating the use of permanent magnets. The generator design presented in this document addresses both these issues with the development of a fully superconducting generator (FSG) with unprecedented high specific torque. A full-scale, 10-MW, 10-rpm generator will weigh less about 150 metric tons, compared to 300 metric tons for an equivalent direct-drive, permanent magnet generator. The developed concept does not use any rare earth materials in its critical drive components, but rather relies on a superconductor composed of mainly magnesium and boron (MgB2), both of which are in abundant supply from multiple global sources.

  8. Influence of omni-directional guide vane on the performance of cross-flow rotor for urban wind energy

    Science.gov (United States)

    Wicaksono, Yoga Arob; Tjahjana, Dominicus Danardono Dwi Prija; Hadi, Syamsul

    2018-02-01

    Vertical axis wind turbine like cross-flow rotor have some advantage there are, high self-starting torque, low noise, and high stability; so, it can be installed in the urban area to produce electricity. But, the urban area has poor wind condition, so the cross-flow rotor needs a guide vane to increase its performance. The aim of this study is to determine experimentally the effect of Omni-Directional Guide Vane (ODGV) on the performance of a cross-flow wind turbine. Wind tunnel experiment has been carried out for various configurations. The ODGV was placed around the cross-flow rotor in order to increase ambient wind environment of the wind turbine. The maximum power coefficient is obtained as Cpmax = 0.125 at 60° wind direction. It was 21.46% higher compared to cross-flow wind turbine without ODGV. This result showed that the ODGV able to increase the performance of the cross-flow wind turbine.

  9. Effect of Wind Angle Direction on Carbon Monoxide (CO) Concentration Dispersion on Traffic Flow in Padang City

    Science.gov (United States)

    Bachtiar, V. S.; Purnawan, P.; Afrianita, R.; Dahlia, N.

    2018-01-01

    This study aims to analyze the relationship between CO concentration and wind direction. Wind direction in this context is the wind angle to the road on the traffic flow in Padang City. Sampling of CO concentration was conducted for 9 days at 3 monitoring points (each 3-day point) representing the wind angle to the road (a) i.e. at Jend. A. Yani road (0 degrees), Andalas road (30 degrees) and Prof. Dr. Hamka road (60 degrees), using impinger and analyzed by spectrophotometer. The results of the research in the three monitoring sites showed that the concentration of CO ranged between 137.217 and 600.525 μg/Nm3. The highest and lowest concentrations respectively on Prof. Dr. Hamka road and Jend. A. Yani road. The sampling showed that CO concentrations will be decreased if wind direction is changed from perpendicular wind direction (a 90°) to a 60°, 30°, and 0° respectively by 64.62%, 37.77% and 27.09%. It can be concluded that the wind angle direction to the road affects the CO concentrations in the roadside.

  10. Measurement of rotor centre flow direction and turbulence in wind farm environment

    DEFF Research Database (Denmark)

    Friis Pedersen, Troels; Demurtas, Giorgio; Sommer, A.

    2014-01-01

    The measurement of inflow to a wind turbine rotor was made with a spinner anemometer on a 2 MW wind turbine in a wind farm of eight wind turbines. The wind speed, yaw misalignment and flow inclination angle was measured during a five months measurement campaign. Angular measurements were calibrat...

  11. Direct solar wind proton access into permanently shadowed lunar polar craters

    Science.gov (United States)

    Zimmerman, M. I.; Farrell, W. M.; Stubbs, T. J.; Halekas, J. S.

    2011-12-01

    Recent analyses of Lunar Prospector neutron spectrometer (LPNS) data have suggested that high abundances of hydrogen exist within cold traps at the lunar poles, and it has often been assumed that hydrogen-bearing volatiles sequestered in permanent shadow are topographically shielded from sputtering by solar wind protons. However, recent simulation results are presented showing that textbf{solar wind protons clearly access the floor of an idealized, shadowed lunar crater} through a combination of thermal and ambipolar processes, in effect creating a plasma "mini-wake". These simulations are the first to model the mini-wake environment in two spatial dimensions with a self-consistent lunar surface-plasma interaction. Progress is reported on constraining the nonzero particle fluxes and energies incident on kilometer-scale shadowed topography, such as a small crater embedded within a larger one. The importance of direct solar wind proton bombardment is discussed within the context of understanding the stability and inventory of hydrogen-bearing volatiles in shadow at the lunar poles. textit{The support of the National Lunar Science Institute, the DREAM Institute, LPROPS, and the NASA Postdoctoral Program at NASA Goddard Space Flight Center administered by ORAU are gratefully acknowledged.}

  12. Direct Solar Wind Proton Access into Permanently Shadowed Lunar Polar Craters

    Science.gov (United States)

    Zimmerman, M. I.; Farrell, W. M.; Stubbs, T. J.; Halekas, J. S.

    2011-01-01

    Recent analyses of Lunar Prospector neutron spectrometer (LPNS) data have suggested that high abundances of hydrogen exist within cold traps at the lunar poles, and it has often been assumed that hydrogen-bearing volatiles sequestered in permanent shadow are topographically shielded from sputtering by solar wind protons. However, recent simulation results are presented showing that solar wind protons clearly access the floor of an idealized, shadowed lunar crater through a combination of thermal and ambipolar processes, in effect creating a plasma "miniwake". These simulations are the first to model the mini-wake environment in two spatial dimensions with a self-consistent lunar surface-plasma interaction. Progress is reported on constraining the nonzero particle fluxes and energies incident on kilometer-scale shadowed topography, such as a small crater embedded within a larger one. The importance of direct solar wind proton bombardment is discussed within the context of understanding the stability and inventory of hydrogen-bearing volatiles in shadow at the lunar poles. The support of the National Lunar Science institute, the DREAM institute, LPROPS, and the NASA Postdoctoral Program at NASA Goddard Space Flight Center administered by ORAU are gratefully acknowledged.

  13. High stability vector-based direct power control for DFIG-based wind turbine

    DEFF Research Database (Denmark)

    Zhu, Rongwu; Chen, Zhe; Wu, Xiaojie

    2015-01-01

    This paper proposes an improved vector-based direct power control (DPC) strategy for the doubly-fed induction generator (DFIG)-based wind energy conversion system. Based on the small signal model, the proposed DPC improves the stability of the DFIG, and avoids the DFIG operating in the marginal...... stable region (the real part of eigenvalue is equal to zero). The vector-based DPC combines with a space vector modulation technique to achieve a constant switching frequency. The simulation and experimental results clearly validate the effectiveness and feasibility of the proposed vector-based DPC...

  14. Effect of land uses and wind direction on the contribution of local sources to airborne pollen

    Energy Technology Data Exchange (ETDEWEB)

    Rojo, Jesús; Rapp, Ana; Lara, Beatriz; Fernández-González, Federico; Pérez-Badia, Rosa

    2015-12-15

    The interpretation of airborne pollen levels in cities based on the contribution of the surrounding flora and vegetation is a useful tool to estimate airborne allergen concentrations and, consequently, to determine the allergy risk for local residents. This study examined the pollen spectrum in a city in central Spain (Guadalajara) and analysed the vegetation landscape and land uses within a radius of 20 km in an attempt to identify and locate the origin of airborne pollen and to determine the effect of meteorological variables on pollen emission and dispersal. The results showed that local wind direction was largely responsible for changes in the concentrations of different airborne pollen types. The land uses contributing most to airborne pollen counts were urban green spaces, though only 0.1% of the total surface area studied, and broadleaved forest which covered 5% of the study area. These two types of land use together accounted for 70% of the airborne pollen. Crops, scrubland and pastureland, though covering 80% of the total surface area, contributed only 18.6% to the total pollen count, and this contribution mainly consisted of pollen from Olea and herbaceous plants, including Poaceae, Urticaceae and Chenopodiaceae–Amaranthaceae. Pollen from ornamental species were mainly associated with easterly (Platanus), southerly (Cupressaceae) and westerly (Cupressaceae and Platanus) winds from the areas where the city's largest parks and gardens are located. Quercus pollen was mostly transported by winds blowing in from holm-oak stands on the eastern edge of the city. The highest Populus pollen counts were associated with easterly and westerly winds blowing in from areas containing rivers and streams. The airborne pollen counts generally rose with increasing temperature, solar radiation and hours of sunlight, all of which favour pollen release. In contrast, pollen counts declined with increased relative humidity and rainfall, which hinder airborne pollen

  15. Effect of land uses and wind direction on the contribution of local sources to airborne pollen

    International Nuclear Information System (INIS)

    Rojo, Jesús; Rapp, Ana; Lara, Beatriz; Fernández-González, Federico; Pérez-Badia, Rosa

    2015-01-01

    The interpretation of airborne pollen levels in cities based on the contribution of the surrounding flora and vegetation is a useful tool to estimate airborne allergen concentrations and, consequently, to determine the allergy risk for local residents. This study examined the pollen spectrum in a city in central Spain (Guadalajara) and analysed the vegetation landscape and land uses within a radius of 20 km in an attempt to identify and locate the origin of airborne pollen and to determine the effect of meteorological variables on pollen emission and dispersal. The results showed that local wind direction was largely responsible for changes in the concentrations of different airborne pollen types. The land uses contributing most to airborne pollen counts were urban green spaces, though only 0.1% of the total surface area studied, and broadleaved forest which covered 5% of the study area. These two types of land use together accounted for 70% of the airborne pollen. Crops, scrubland and pastureland, though covering 80% of the total surface area, contributed only 18.6% to the total pollen count, and this contribution mainly consisted of pollen from Olea and herbaceous plants, including Poaceae, Urticaceae and Chenopodiaceae–Amaranthaceae. Pollen from ornamental species were mainly associated with easterly (Platanus), southerly (Cupressaceae) and westerly (Cupressaceae and Platanus) winds from the areas where the city's largest parks and gardens are located. Quercus pollen was mostly transported by winds blowing in from holm-oak stands on the eastern edge of the city. The highest Populus pollen counts were associated with easterly and westerly winds blowing in from areas containing rivers and streams. The airborne pollen counts generally rose with increasing temperature, solar radiation and hours of sunlight, all of which favour pollen release. In contrast, pollen counts declined with increased relative humidity and rainfall, which hinder airborne pollen

  16. Atmospheric infrasound propagation modelling using the reflectivity method with a direct formulation of the wind effect

    Science.gov (United States)

    Maupin, Valerie; Näsholm, Sven Peter; Schweitzer, Johannes; Gibbons, Steven J.

    2016-04-01

    We recently advocated using the reflectivity method, also known as the wavenumber integration method or fast-field program, to model atmospheric infrasound propagation at regional distances. The advantage of the reflectivity method is its ability to model the full wavefield, including diffractive effects with head waves and shadow zone arrivals, in a broad frequency range but still at a relatively low computational cost. Attenuation can easily be included, giving the possibility to analyse relative amplitudes and frequency content of the different arrivals. It has clear advantages compared with ray theory in terms of predicting phases considering the particular frequent occurrence of shadow zone arrivals in infrasound observations. Its main limitation, at least in the traditional form of the method, lies in the fact that it can only handle range-independent models. We presented earlier some reflectivity method simulations of an observed accidental explosion in Norway. Wind intensity and direction are non-negligible parameters for infrasound propagation and these are appropriately taken into account in most infrasound ray-tracing codes. On the other hand, in the previous reflectivity simulations wind was taken into account only through the effective sound speed approximation where the horizontal projection of the wind field is added to the adiabatic sound speed profiles. This approximation is appropriate for dominantly horizontal propagation but can give incorrect arrival times and shadow zone locations for waves which have a significant portion of their propagation path at more vertical incidence, like thermospheric arrivals. We present here how we have modified the original reflectivity algorithm in order to take the wind into account in a more correct fashion, and how this improvement influences the synthetics.

  17. Effects of vernal equinox solar eclipse on temperature and wind direction in Switzerland

    Science.gov (United States)

    Eugster, Werner; Emmel, Carmen; Wolf, Sebastian; Buchmann, Nina; McFadden, Joseph P.; Whiteman, Charles David

    2017-12-01

    The vernal equinox total solar eclipse of 20 March 2015 produced a maximum occultation of 65.8-70.1 % over Switzerland during the morning hours (09:22 to 11:48 CET). Skies were generally clear over the Swiss Alps due to a persistent high-pressure band between the UK and Russia associated with a rather weak pressure gradient over the continent. To assess the effects of penumbral shading on near-surface meteorology across Switzerland, air temperature data measured at 10 min intervals at 184 MeteoSwiss weather stations were used. Wind speed and direction data were available from 165 of these stations. Additionally, six Swiss FluxNet eddy covariance flux (ECF) sites provided turbulent measurements at 20 Hz resolution. During maximum occultation, the temperature drop was up to 5.8 K at a mountain site where cold air can pool in a topographic depression. The bootstrapped average of the maximum temperature drops of all 184 MeteoSwiss sites during the solar eclipse was 1.51 ± 0.02 K (mean ± SE). A detailed comparison with literature values since 1834 showed a temperature decrease of 2.6 ± 1.7 K (average of all reports), with extreme values up to 11 K. On fair weather days under weak larger-scale pressure gradients, local thermo-topographic wind systems develop that are driven by small-scale pressure and temperature gradients. At one ECF site, the penumbral shading delayed the morning transition from down-valley to up-valley wind conditions. At another site, it prevented this transition from occurring at all. Data from the 165 MeteoSwiss sites measuring wind direction did not show a consistent pattern of wind direction response to the passing of the penumbral shadow. These results suggest that the local topographic setting had an important influence on the temperature drop and the wind flow patterns during the eclipse. A significant cyclonic effect of the passing penumbral shadow was found in the elevation range ≈ 1700-2700 m a. s. l., but not at lower

  18. Effects of vernal equinox solar eclipse on temperature and wind direction in Switzerland

    Directory of Open Access Journals (Sweden)

    W. Eugster

    2017-12-01

    Full Text Available The vernal equinox total solar eclipse of 20 March 2015 produced a maximum occultation of 65.8–70.1 % over Switzerland during the morning hours (09:22 to 11:48 CET. Skies were generally clear over the Swiss Alps due to a persistent high-pressure band between the UK and Russia associated with a rather weak pressure gradient over the continent. To assess the effects of penumbral shading on near-surface meteorology across Switzerland, air temperature data measured at 10 min intervals at 184 MeteoSwiss weather stations were used. Wind speed and direction data were available from 165 of these stations. Additionally, six Swiss FluxNet eddy covariance flux (ECF sites provided turbulent measurements at 20 Hz resolution. During maximum occultation, the temperature drop was up to 5.8 K at a mountain site where cold air can pool in a topographic depression. The bootstrapped average of the maximum temperature drops of all 184 MeteoSwiss sites during the solar eclipse was 1.51 ± 0.02 K (mean ± SE. A detailed comparison with literature values since 1834 showed a temperature decrease of 2.6 ± 1.7 K (average of all reports, with extreme values up to 11 K. On fair weather days under weak larger-scale pressure gradients, local thermo-topographic wind systems develop that are driven by small-scale pressure and temperature gradients. At one ECF site, the penumbral shading delayed the morning transition from down-valley to up-valley wind conditions. At another site, it prevented this transition from occurring at all. Data from the 165 MeteoSwiss sites measuring wind direction did not show a consistent pattern of wind direction response to the passing of the penumbral shadow. These results suggest that the local topographic setting had an important influence on the temperature drop and the wind flow patterns during the eclipse. A significant cyclonic effect of the passing penumbral shadow was found in the elevation range

  19. A wind-tunnel investigation of parameters affecting helicopter directional control at low speeds in ground effect

    Science.gov (United States)

    Yeager, W. T., Jr.; Young, W. H., Jr.; Mantay, W. R.

    1974-01-01

    An investigation was conducted in the Langley full-scale tunnel to measure the performance of several helicopter tail-rotor/fin configurations with regard to directional control problems encountered at low speeds in ground effect. Tests were conducted at wind azimuths of 0 deg to 360 deg in increments of 30 deg and 60 deg and at wind speeds from 0 to 35 knots. The results indicate that at certain combinations of wind speed and wind azimuth, large increases in adverse fin force require correspondingly large increases in the tail-rotor thrust, collective pitch, and power required to maintain yaw trim. Changing the tail-rotor direction of rotation to top blade aft for either a pusher tail rotor (tail-rotor wake blowing away from fin) or a tractor tail rotor (tail-rotor wake blowing against fin) will alleviate this problem. For a pusher tail rotor at 180 deg wind azimuth, increases in the fin/tail-rotor gap were not found to have any significant influence on the overall vehicle directional control capability. Changing the tail rotor to a higher position was found to improve tail-rotor performance for a fin-off configuration at a wind azimuth of 180 deg. A V-tail configuration with a pusher tail rotor with top blade aft direction of rotation was found to be the best configuration with regard to overall directional control capability.

  20. Reduction of Cogging Torque in Dual Rotor Permanent Magnet Generator for Direct Coupled Wind Energy Systems

    Directory of Open Access Journals (Sweden)

    Sivachandran Paulsamy

    2014-01-01

    Full Text Available In wind energy systems employing permanent magnet generator, there is an imperative need to reduce the cogging torque for smooth and reliable cut in operation. In a permanent magnet generator, cogging torque is produced due to interaction of the rotor magnets with slots and teeth of the stator. This paper is a result of an ongoing research work that deals with various methods to reduce cogging torque in dual rotor radial flux permanent magnet generator (DRFPMG for direct coupled stand alone wind energy systems (SAWES. Three methods were applied to reduce the cogging torque in DRFPMG. The methods were changing slot opening width, changing magnet pole arc width and shifting of slot openings. A combination of these three methods was applied to reduce the cogging torque to a level suitable for direct coupled SAWES. Both determination and reduction of cogging torque were carried out by finite element analysis (FEA using MagNet Software. The cogging torque of DRFPMG has been reduced without major change in induced emf. A prototype of 1 kW, 120 rpm DRFPMG was fabricated and tested to validate the simulation results. The test results have good agreement with the simulation predictions.

  1. Direct-phase-variable model of a synchronous reluctance motor including all slot and winding harmonics

    International Nuclear Information System (INIS)

    Obe, Emeka S.; Binder, A.

    2011-01-01

    A detailed model in direct-phase variables of a synchronous reluctance motor operating at mains voltage and frequency is presented. The model includes the stator and rotor slot openings, the actual winding layout and the reluctance rotor geometry. Hence, all mmf and permeance harmonics are taken into account. It is seen that non-negligible harmonics introduced by slots are present in the inductances computed by the winding function procedure. These harmonics are usually ignored in d-q models. The machine performance is simulated in the stator reference frame to depict the difference between this new direct-phase model including all harmonics and the conventional rotor reference frame d-q model. Saturation is included by using a polynomial fitting the variation of d-axis inductance with stator current obtained by finite-element software FEMAG DC (registered) . The detailed phase-variable model can yield torque pulsations comparable to those obtained from finite elements while the d-q model cannot.

  2. Design Considerations of a Transverse Flux Machine for Direct-Drive Wind Turbine Applications

    Energy Technology Data Exchange (ETDEWEB)

    Husain, Tausif; Hasan, Iftekhar; Sozer, Yilmaz; Husain, Iqbal; Muljadi, Eduard

    2017-02-16

    This paper presents the design considerations of a double-sided transverse flux machine (TFM) for direct-drive wind turbine applications. The TFM has a modular structure with quasi-U stator cores and ring windings. The rotor is constructed with ferrite magnets in a flux-concentrating arrangement to achieve high air gap flux density. The design considerations for this TFM with respect to initial sizing, pole number selection, key design ratios, and pole shaping are presented in this paper. Pole number selection is critical in the design process of a TFM because it affects both the torque density and power factor under fixed magnetic and changing electrical loading. Several key design ratios are introduced to facilitate the design procedure. The effect of pole shaping on back-emf and inductance is also analyzed. These investigations provide guidance toward the required design of a TFM for direct-drive applications. The analyses are carried out using analytical and three-dimensional finite element analysis. A prototype is under construction for experimental verification.

  3. Design Considerations of a Transverse Flux Machine for Direct-Drive Wind Turbine Applications: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Husain, Tausif; Hasan, Iftekhar; Sozer, Yilmaz; Husain, Iqbal; Muljadi, Eduard

    2017-01-01

    This paper presents the design considerations of a double-sided transverse flux machine (TFM) for direct-drive wind turbine applications. The TFM has a modular structure with quasi-U stator cores and ring windings. The rotor is constructed with ferrite magnets in a flux-concentrating arrangement to achieve high air gap flux density. The design considerations for this TFM with respect to initial sizing, pole number selection, key design ratios, and pole shaping are presented in this paper. Pole number selection is critical in the design process of a TFM because it affects both the torque density and power factor under fixed magnetic and changing electrical loading. Several key design ratios are introduced to facilitate the design procedure. The effect of pole shaping on back-emf and inductance is also analyzed. These investigations provide guidance toward the required design of a TFM for direct-drive applications. The analyses are carried out using analytical and three-dimensional finite element analysis. A prototype is under construction for experimental verification.

  4. Reduction of cogging torque in dual rotor permanent magnet generator for direct coupled wind energy systems.

    Science.gov (United States)

    Paulsamy, Sivachandran

    2014-01-01

    In wind energy systems employing permanent magnet generator, there is an imperative need to reduce the cogging torque for smooth and reliable cut in operation. In a permanent magnet generator, cogging torque is produced due to interaction of the rotor magnets with slots and teeth of the stator. This paper is a result of an ongoing research work that deals with various methods to reduce cogging torque in dual rotor radial flux permanent magnet generator (DRFPMG) for direct coupled stand alone wind energy systems (SAWES). Three methods were applied to reduce the cogging torque in DRFPMG. The methods were changing slot opening width, changing magnet pole arc width and shifting of slot openings. A combination of these three methods was applied to reduce the cogging torque to a level suitable for direct coupled SAWES. Both determination and reduction of cogging torque were carried out by finite element analysis (FEA) using MagNet Software. The cogging torque of DRFPMG has been reduced without major change in induced emf. A prototype of 1 kW, 120 rpm DRFPMG was fabricated and tested to validate the simulation results. The test results have good agreement with the simulation predictions.

  5. Influence of hurricane wind field in the structure of directional wave spectra.

    Science.gov (United States)

    Esquivel-Trava, Bernardo; García-Nava, Hector; Osuna, Pedro; Ocampo-Torres, Francisco J.

    2017-04-01

    Three numerical experiments using the spectral wave prediction model SWAN were carried out to gain insight into the mechanism that controls the directional and frequency distributions of hurricane wave energy. One particular objective is to evaluate the effect of the translation speed of the hurricane and the presence of concentric eye walls, on both the wave growth process and the shape of the directional wave spectrum. The HRD wind field of Hurricane Dean on August 20 at 7:30 was propagated at two different velocities (5 and 10 m/s). An idealized concentric eye wall (a Gaussian function that evolve in time along a path in the form of an Archimedean spiral) was imposed to the wind field. The white-capping formulation of Westhuysen et al. (2007) was selected. The wave model represents fairly well the directionality of the energy and the shape of the directional spectra in the hurricane domain. The model results indicate that the forward movement of the storm influences the development of the waves, consistent with field observations. Additionally the same experiments were carried out using the Wave Watch III model with the source terms formulation proposed by Ardhuin et al., 2010, with the aim of making comparisons between the physical processes that represent each formulation, and the latest results will be addressed. References Ardhuin, F., Rogers, E., Babanin, A. V., Filipot, J.-F., Magne, R., Roland, A., van der Westhuysen, A., et al. (2010). Semiempirical Dissipation Source Functions for Ocean Waves. Part I: Definition, Calibration, and Validation. Journal of Physical Oceanography, 40(9), 1917-1941. doi:10.1175/2010JPO4324.1 Van der Westhuysen, A. J., Zijlema, M., & Battjes, J. A. (2007). Nonlinear saturation-based whitecapping dissipation in SWAN for deep and shallow water. Coast. Eng., 54(2), 151-170. doi:10.1016/j.coastaleng.2006.08.006

  6. Effect of wind direction and speed on the dispersion of nucleation and accumulation mode particles in an urban street canyon.

    Science.gov (United States)

    Kumar, Prashant; Fennell, Paul; Britter, Rex

    2008-08-25

    There have been many studies concerning dispersion of gaseous pollutants from vehicles within street canyons; fewer address the dispersion of particulate matter, particularly particle number concentrations separated into the nucleation (10-30 nm or N10-30) or accumulation (30-300 nm or N30-300) modes either separately or together (N10-300). This study aimed to determine the effect of wind direction and speed on particle dispersion in the above size ranges. Particle number distributions (PNDs) and concentrations (PNCs) were measured in the 5-2738 nm range continuously (and in real-time) for 17 days between 7th and 23rd March 2007 in a regular (aspect ratio approximately unity) street canyon in Cambridge (UK), using a newly developed fast-response differential mobility spectrometer (sampling frequency 0.5 Hz), at 1.60 m above the road level. The PNCs in each size range, during all wind directions, were better described by a proposed two regime model (traffic-dependent and wind-dependent mixing) than by simply assuming that the PNC was inversely proportional to the wind speed or by fitting the data with a best-fit single power law. The critical cut-off wind speed (Ur,crit) for each size range of particles, distinguishing the boundary between these mixing regimes was also investigated. In the traffic-dependent PNC region (UrUrwind speed and direction. In the wind speed dependent PNC region (UrUr>Ur,critUr,crit), concentrations were inversely proportional to Ur irrespective of any particle size range and wind directions. The wind speed demarcating the two regimes (Ur,critUr,crit) was 1.23+/-0.55 m s(-1) for N10-300, (1.47+/-0.72 m s(-1)) for N10-30 but smaller (0.78+/-0.29 m s(-1)) for N30-300.

  7. Direct numerical simulations of an arc-powered heater for used in a hypersonic wind tunnel

    Science.gov (United States)

    Kim, Pilbum; Panesi, Marco; Freund, Jonathan

    2017-11-01

    We study a model arc-heater using direct numerical simulations, in a configuration motivated by its used to generated inflow of a high-speed wind tunnel for hypersonics research. The flow is assumed to be in local thermal equilibrium (LTE) and is modeled with with 11 species (N2, O2, NO, N, O, N2+,O2+,NO+, N+, O+, e-). The flow equations are solved in conjunction with an electrostatic field solver and the gas electric conductivity in LTE. The flow rate and the mean arc power are set to be 50.42 g/s and 84.7 kW with 214.0 V of the mean arc voltage , respectively. We study the flow details, the heading and thrust mechanisms, and make general comparisons with a corresponding, though geometrically more complex, experimental configuration. We particularly interested in the radical species it produces and will potentially be present in the wind-tunnel test section. This material is based in part upon work supported by the Department of Energy, National Nuclear Security Administration, under Award Number DE-NA0002374.

  8. Sliding mode direct power control of RSC for DFIGs driven by variable speed wind turbines

    Directory of Open Access Journals (Sweden)

    E.G. Shehata

    2015-12-01

    Full Text Available In spite of its several advantages, a classic direct power control (DPC of doubly fed induction generators (DFIGs driven by variable speed wind turbines has some drawbacks. In this paper, a simple and robust total sliding mode controller (TSMC is designed to improve the classical DPC performance without complicating the overall scheme. The TSMC is designed to regulate the DFIG stator active and reactive powers. Two integral switching functions are selected for describing the switching surfaces of the active and reactive powers. Reaching phase stability problem of the classical sliding mode controller is avoided in the proposed TSMC. Neither current control loops nor accurate values of machine parameters are required in the proposed scheme. In addition, axes transformation of the stator voltage and current are eliminated. The grid side converter is controlled based on DPC principle to regulate both DC-link voltage and total reactive power. The feasibility of the proposed DPC scheme is validated through simulation studies on a 1.5 MW wind power generation system. The performance of the proposed and conventional DPC schemes is compared under different operating conditions.

  9. The Tropospheric Wind Lidar Technology Experiment (TWiLiTE): An Airborne Direct Detection Doppler Lidar Instrument Development Program

    Science.gov (United States)

    Gentry, Bruce; McGill, Matthew; Schwemmer, Geary; Hardesty, Michael; Brewer, Alan; Wilkerson, Thomas; Atlas, Robert; Sirota, Marcos; Lindemann, Scott

    2006-01-01

    Global measurement of tropospheric winds is a key measurement for understanding atmospheric dynamics and improving numerical weather prediction. Global wind profiles remain a high priority for the operational weather community and also for a variety of research applications including studies of the global hydrologic cycle and transport studies of aerosols and trace species. In addition to space based winds, a high altitude airborne system flown on UAV or other advanced platforms would be of great interest for studying mesoscale dynamics and hurricanes. The Tropospheric Wind Lidar Technology Experiment (TWiLiTE) project was selected in 2005 by the NASA Earth Sun Technology Office as part of the Instrument Incubator Program. TWiLiTE will leverage significant research and development investments in key technologies made in the past several years. The primary focus will be on integrating these sub-systems into a complete molecular direct detection Doppler wind lidar system designed for autonomous operation on a high altitude aircraft, such as the NASA WB57, so that the nadir viewing lidar will be able to profile winds through the full troposphere. TWiLiTE is a collaboration involving scientists and technologists from NASA Goddard, NOAA ESRL, Utah State University Space Dynamics Lab and industry partners Michigan Aerospace Corporation and Sigma Space Corporation. NASA Goddard and it's partners have been at the forefront in the development of key lidar technologies (lasers, telescopes, scanning systems, detectors and receivers) required to enable spaceborne global wind lidar measurement. The TWiLiTE integrated airborne Doppler lidar instrument will be the first demonstration of a airborne scanning direct detection Doppler lidar and will serve as a critical milestone on the path to a fixture spaceborne tropospheric wind system. The completed system will have the capability to profile winds in clear air from the aircraft altitude of 18 h to the surface with 250 m vertical

  10. Direct Numerical Simulation of Acoustic Noise Generation from the Nozzle Wall of a Hypersonic Wind Tunnel

    Science.gov (United States)

    Huang, Junji; Duan, Lian; Choudhari, Meelan; Missouri Univ of Sci; Tech Team; NASA Langley Research Center Team

    2017-11-01

    Direct numerical simulations (DNS) are used to examine the acoustic noise generation from the turbulent boundary layer on the nozzle wall of a Mach 6 Ludwieg Tube. The emphasis is on characterizing the freestream acoustic pressure disturbances radiated from the nozzle-wall turbulent boundary layer and comparing it with acoustic noise generated from a single, flat wall in an unconfined setting at a similar freestream Mach number to assess the effects of noise reverberation. In particular, the numerical database is used to provide insights into the pressure disturbance spectrum and amplitude scaling with respect to the boundary-layer parameters as well as to understand the acoustic source mechanisms. Such information is important for characterizing the freestream disturbance environment in conventional (i.e., noisy) hypersonic wind tunnels. Air Force Office of Scientific Research Award No. FA9550-14-1-0170.

  11. 76 FR 47353 - Final Directives for Forest Service Wind Energy Special Use Authorizations, Forest Service Manual...

    Science.gov (United States)

    2011-08-04

    ...- specific conditions, such as wildlife habitat, topography, and climate. Response. The Agency is familiar... person or small team to coordinate wind energy projects for all regions and process all wind energy... recommended that the Agency develop national siting criteria for wind energy projects and an inventory of...

  12. Bi-directional vibration control of offshore wind turbines using a 3D pendulum tuned mass damper

    Science.gov (United States)

    Sun, C.; Jahangiri, V.

    2018-05-01

    Offshore wind turbines suffer from excessive bi-directional vibrations due to wind-wave misalignment and vortex induced vibrations. However, most of existing research focus on unidirectional vibration attenuation which is inadequate for real applications. The present paper proposes a three dimensional pendulum tuned mass damper (3d-PTMD) to mitigate the tower and nacelle dynamic response in the fore-aft and side-side directions. An analytical model of the wind turbine coupled with the 3d-PTMD is established wherein the interaction between the blades, the tower and the 3d-PTMD is modeled. Aerodynamic loading is computed using the Blade Element Momentum method where the Prandtls tip loss factor and the Glauert correction are considered. JONSWAP spectrum is adopted to generate wave data. Wave loading is computed using Morisons equation in collaboration with the strip theory. Via a numerical search approach, the design formula of the 3d-PTMD is obtained and examined on a National Renewable Energy Lab (NREL) monopile 5 MW baseline wind turbine model under misaligned wind, wave and seismic loading. Dual linear tuned mass dampers (TMDs) deployed in the fore-aft and side-side directions are utilized for comparison. It is found that the 3d-PTMD with a mass ratio of 2 % can improve the mitigation of the root mean square and peak response by around 10 % when compared with the dual linear TMDs in controlling the bi-directional vibration of the offshore wind turbines under misaligned wind, wave and seismic loading.

  13. Summary Report: The Shadow effect of large wind farms: measurements, data analysis and modelling

    DEFF Research Database (Denmark)

    Frandsen, Sten Tronæs; Barthelmie, Rebecca Jane; Rathmann, Ole

    It was the goal of the project – by means of data from the demonstration wind farms Horns Rev and Nysted, analyses of these data and modelling – to facilitate prediction of the power losses from a wind farm should a new wind farm be built upwind relative to the prevailing wind direction......: • Measurements were carried out at the Nysted and Horns Rev demonstration wind farms for several years. Doing so included design, installation and operation of the measurement system • A data base was built from the incoming data. The data have been organized to facilitate verification of the models developed....... Or conversely, predict with adequate accuracy the production of a new wind farm built downwind of an existing wind farm. The project should be seen in the perspective of the two existing demonstration wind farms that extend 5-10 km in each direction. In order to e.g. use the existing electrical infrastructure...

  14. Laboratory investigation and direct numerical simulation of wind effect on steep surface waves

    Science.gov (United States)

    Troitskaya, Yuliya; Sergeev, Daniil; Druzhinin, Oleg; Ermakova, Olga

    2015-04-01

    particles 20 μm in diameter were injected into the airflow. The images of the illuminated particles were photographed with a digital CCD video camera at a rate of 1000 frames per second. For the each given parameters of wind and waves, a statistical ensemble of 30 movies with duration from 200 to 600 ms was obtained. Individual flow realizations manifested the typical features of flow separation, while the average vector velocity fields obtained by the phase averaging of the individual vector fields were smooth and slightly asymmetrical, with the minimum of the horizontal velocity near the water surface shifted to the leeward side of the wave profile, but do not demonstrate the features of flow separation. The wave-induced pressure perturbations, averaged over the turbulent fluctuations, were retrieved from the measured velocity fields, using the Reynolds equations. It ensures sufficient accuracy for study of the dependence of the wave increment on the wave amplitude. The dependences of the wave growth rate on the wave steepness are weakly decreasing, serving as indirect proof of the non-separated character of flow over waves. Also direct numerical simulation of the airflow over finite amplitude periodic surface wave was performed. In the experiments the primitive 3-dimensional fluid mechanics equations were solved in the airflow over curved water boundary for the following parameters: the Reynolds number Re=15000, the wave steepness ka=0-0.2, the parameter c/u*=0-10 (where u* is the friction velocity and c is the wave celerity). Similar to the physical experiment the instant realizations of the velocity field demonstrate flow separation at the crests of the waves, but the ensemble averaged velocity fields had typical structures similar to those excising in shear flows near critical levels, where the phase velocity of the disturbance coincides with the flow velocity. The wind growth rate determined by the ensemble averaged wave-induced pressure component in phase of the

  15. Rotor Speed Control of a Direct-Driven Permanent Magnet Synchronous Generator-Based Wind Turbine Using Phase-Lag Compensators to Optimize Wind Power Extraction

    Directory of Open Access Journals (Sweden)

    Ester Hamatwi

    2017-01-01

    Full Text Available Due to the intermittent nature of wind, the wind power output tends to be inconsistent, and hence maximum power point tracking (MPPT is usually employed to optimize the power extracted from the wind resource at a wide range of wind speeds. This paper deals with the rotor speed control of a 2 MW direct-driven permanent magnet synchronous generator (PMSG to achieve MPPT. The proportional-integral (PI, proportional-derivative (PD, and proportional-integral-derivative (PID controllers have widely been employed in MPPT studies owing to their simple structure and simple design procedure. However, there are a number of shortcomings associated with these controllers; the trial-and-error design procedure used to determine the P, I, and D gains presents a possibility for poorly tuned controller gains, which reduces the accuracy and the dynamic performance of the entire control system. Moreover, these controllers’ linear nature, constricted operating range, and their sensitivity to changes in machine parameters make them ineffective when applied to nonlinear and uncertain systems. On the other hand, phase-lag compensators are associated with a design procedure that is well defined from fundamental principles as opposed to the aforementioned trial-and-error design procedure. This makes the latter controller type more accurate, although it is not well developed yet, and hence it is the focus of this paper. The simulation results demonstrated the effectiveness of the proposed MPPT controller.

  16. Towards an automatic wind speed and direction profiler for Wide Field adaptive optics systems

    Science.gov (United States)

    Sivo, G.; Turchi, A.; Masciadri, E.; Guesalaga, A.; Neichel, B.

    2018-05-01

    Wide Field Adaptive Optics (WFAO) systems are among the most sophisticated adaptive optics (AO) systems available today on large telescopes. Knowledge of the vertical spatio-temporal distribution of wind speed (WS) and direction (WD) is fundamental to optimize the performance of such systems. Previous studies already proved that the Gemini Multi-Conjugated AO system (GeMS) is able to retrieve measurements of the WS and WD stratification using the SLOpe Detection And Ranging (SLODAR) technique and to store measurements in the telemetry data. In order to assess the reliability of these estimates and of the SLODAR technique applied to such complex AO systems, in this study we compared WS and WD values retrieved from GeMS with those obtained with the atmospheric model Meso-NH on a rich statistical sample of nights. It has previously been proved that the latter technique provided excellent agreement with a large sample of radiosoundings, both in statistical terms and on individual flights. It can be considered, therefore, as an independent reference. The excellent agreement between GeMS measurements and the model that we find in this study proves the robustness of the SLODAR approach. To bypass the complex procedures necessary to achieve automatic measurements of the wind with GeMS, we propose a simple automatic method to monitor nightly WS and WD using Meso-NH model estimates. Such a method can be applied to whatever present or new-generation facilities are supported by WFAO systems. The interest of this study is, therefore, well beyond the optimization of GeMS performance.

  17. Modelling and Analysis of Radial Flux Surface Mounted Direct-Driven PMSG in Small Scale Wind Turbine

    Directory of Open Access Journals (Sweden)

    Theint Zar Htet

    2017-11-01

    Full Text Available This paper presents the modelling and analysis of permanent magnet synchronous generator (PMSG which are used in direct driven small scale wind turbines. The 3 kW PM generator which is driven directly without gear system is analyzed by Ansoft Maxwell 2D RMxprt. The performance analysis of generator includes the cogging torque in two teeth, induced coil voltages under load, winding current under load, airgap flux density distribution and so on. The modelling analysis is based on the 2D finite element techniques. In an electrical machine, an accurate determination of the geometry parameters is a vital role. The proper performance results of 3kW PMSG in small scale wind turbine can be seen in this paper.

  18. Federal Prevailing Rate Advisory Committee (FPRAC) Annual Reports

    Data.gov (United States)

    Office of Personnel Management — Annual reports of the Federal Prevailing Rate Advisory Committee (FPRAC), which studies the prevailing (market) rate system for wages and other matters pertinent to...

  19. Directed flight and optimal airspeeds: homeward-bound gulls react flexibly to wind yet fly slower than predicted

    NARCIS (Netherlands)

    McLaren, J.D.; Shamoun, J.; Camphuysen, C.J.; Bouten, W.

    2016-01-01

    Birds in flight are proposed to adjust their body orientation (heading) and airspeed to wind conditions adaptively according to time and energy constraints. Airspeeds in goal-directed flight are predicted to approach or exceed maximum-range airspeeds, which minimize transport costs (energy

  20. Field intercomparison of prevailing sonic anemometers

    Science.gov (United States)

    Mauder, Matthias; Zeeman, Matthias J.

    2018-01-01

    Three-dimensional sonic anemometers are the core component of eddy covariance systems, which are widely used for micrometeorological and ecological research. In order to characterize the measurement uncertainty of these instruments we present and analyse the results from a field intercomparison experiment of six commonly used sonic anemometer models from four major manufacturers. These models include Campbell CSAT3, Gill HS-50 and R3, METEK uSonic-3 Omni, R. M. Young 81000 and 81000RE. The experiment was conducted over a meadow at the TERENO/ICOS site DE-Fen in southern Germany over a period of 16 days in June of 2016 as part of the ScaleX campaign. The measurement height was 3 m for all sensors, which were separated by 9 m from each other, each on its own tripod, in order to limit contamination of the turbulence measurements by adjacent structures as much as possible. Moreover, the high-frequency data from all instruments were treated with the same post-processing algorithm. In this study, we compare the results for various turbulence statistics, which include mean horizontal wind speed, standard deviations of vertical wind velocity and sonic temperature, friction velocity, and the buoyancy flux. Quantitative measures of uncertainty, such as bias and comparability, are derived from these results. We find that biases are generally very small for all sensors and all computed variables, except for the sonic temperature measurements of the two Gill sonic anemometers (HS and R3), confirming a known transducer-temperature dependence of the sonic temperature measurement. The best overall agreement between the different instruments was found for the mean wind speed and the buoyancy flux.

  1. Field intercomparison of prevailing sonic anemometers

    Directory of Open Access Journals (Sweden)

    M. Mauder

    2018-01-01

    Full Text Available Three-dimensional sonic anemometers are the core component of eddy covariance systems, which are widely used for micrometeorological and ecological research. In order to characterize the measurement uncertainty of these instruments we present and analyse the results from a field intercomparison experiment of six commonly used sonic anemometer models from four major manufacturers. These models include Campbell CSAT3, Gill HS-50 and R3, METEK uSonic-3 Omni, R. M. Young 81000 and 81000RE. The experiment was conducted over a meadow at the TERENO/ICOS site DE-Fen in southern Germany over a period of 16 days in June of 2016 as part of the ScaleX campaign. The measurement height was 3 m for all sensors, which were separated by 9 m from each other, each on its own tripod, in order to limit contamination of the turbulence measurements by adjacent structures as much as possible. Moreover, the high-frequency data from all instruments were treated with the same post-processing algorithm. In this study, we compare the results for various turbulence statistics, which include mean horizontal wind speed, standard deviations of vertical wind velocity and sonic temperature, friction velocity, and the buoyancy flux. Quantitative measures of uncertainty, such as bias and comparability, are derived from these results. We find that biases are generally very small for all sensors and all computed variables, except for the sonic temperature measurements of the two Gill sonic anemometers (HS and R3, confirming a known transducer-temperature dependence of the sonic temperature measurement. The best overall agreement between the different instruments was found for the mean wind speed and the buoyancy flux.

  2. Earth aeolian wind streaks: Comparison to wind data from model and stations

    Science.gov (United States)

    Cohen-Zada, A. L.; Maman, S.; Blumberg, D. G.

    2017-05-01

    Wind streak is a collective term for a variety of aeolian features that display distinctive albedo surface patterns. Wind streaks have been used to map near-surface winds and to estimate atmospheric circulation patterns on Mars and Venus. However, because wind streaks have been studied mostly on Mars and Venus, much of the knowledge regarding the mechanism and time frame of their formation and their relationship to the atmospheric circulation cannot be verified. This study aims to validate previous studies' results by a comparison of real and modeled wind data with wind streak orientations as measured from remote-sensing images. Orientations of Earth wind streaks were statistically correlated to resultant drift direction (RDD) values calculated from reanalysis and wind data from 621 weather stations. The results showed good agreement between wind streak orientations and reanalysis RDD (r = 0.78). A moderate correlation was found between the wind streak orientations and the weather station data (r = 0.47); a similar trend was revealed on a regional scale when the analysis was performed by continent, with r ranging from 0.641 in North America to 0.922 in Antarctica. At sites where wind streak orientations did not correspond to the RDDs (i.e., a difference of 45°), seasonal and diurnal variations in the wind flow were found to be responsible for deviation from the global pattern. The study thus confirms that Earth wind streaks were formed by the present wind regime and they are indeed indicative of the long-term prevailing wind direction on global and regional scales.

  3. Design and Comparison of a Novel Stator Interior Permanent Magnet Generator for Direct-Drive Wind Turbines

    DEFF Research Database (Denmark)

    Zhang, Johan Xi; Chen, Zhe; Cheng, M.

    2007-01-01

    A novel stator interior permanent magnet generator (SIPMG) is presented. A modular stator design is used for convenience in manufacture and maintenance. The generator has the advantages of rugged rotor and concentrated winding design whereas the torque ripple is smaller than that produced...... by a doubly salient machine. Several low-speed multi-pole SIPMGs are designed for direct-drive wind turbines with ratings from 3 to 10 MW. Comparisons between the SIPMG and rotor-surface-mounted permanent magnet synchronous generator (PMSG) show that the SIPMGs have about 120% torque density and 78% cost per...

  4. Microbiology of Wind-eroded Sediments: Current Knowledge and Future Research Directions

    Science.gov (United States)

    Wind erosion is a threat to the sustainability and productivity of soils that takes place at local, regional, and global scales. Current estimates of cost of wind erosion have not included the costs associated with the loss of soil biodiversity and reduced ecosystem functions. Microorganisms carrie...

  5. Plants and ventifacts delineate late Holocene wind vectors in the Coachella Valley, USA

    Science.gov (United States)

    Griffiths, P.G.; Webb, R.H.; Fisher, M.; Muth, Allan

    2009-01-01

    Strong westerly winds that emanate from San Gorgonio Pass, the lowest point between Palm Springs and Los Angeles, California, dominate aeolian transport in the Coachella Valley of the western Sonoran Desert. These winds deposit sand in coppice dunes that are critical habitat for several species, including the state and federally listed threatened species Uma inornata, a lizard. Although wind directions are generally defined in this valley, the wind field has complex interactions with local topography and becomes more variable with distance from the pass. Local, dominant wind directions are preserved by growth patterns of Larrea tridentata (creosote bush), a shrub characteristic of the hot North American deserts, and ventifacts. Exceptionally long-lived, Larrea has the potential to preserve wind direction over centuries to millennia, shaped by the abrasive pruning of windward branches and the persistent training of leeward branches. Wind direction preserved in Larrea individuals and clones was mapped at 192 locations. Compared with wind data from three weather stations, Larrea vectors effectively reflect annual prevailing winds. Ventifacts measured at 24 locations record winds 10° more westerly than Larrea and appear to reflect the direction of the most erosive winds. Based on detailed mapping of local wind directions as preserved in Larrea, only the northern half of the Mission-Morongo Creek floodplain is likely to supply sand to protected U. inornata habitat in the Willow Hole ecological reserve.

  6. Plants and ventifacts delineate late Holocene wind vectors in the Coachella Valley, USA

    Science.gov (United States)

    Griffiths, Peter G.; Webb, Robert H.; Fisher, Mark; Muth, Allan

    Strong westerly winds that emanate from San Gorgonio Pass, the lowest point between Palm Springs and Los Angeles, California, dominate aeolian transport in the Coachella Valley of the western Sonoran Desert. These winds deposit sand in coppice dunes that are critical habitat for several species, including the state and federally listed threatened species Uma inornata, a lizard. Although wind directions are generally defined in this valley, the wind field has complex interactions with local topography and becomes more variable with distance from the pass. Local, dominant wind directions are preserved by growth patterns of Larrea tridentata (creosote bush), a shrub characteristic of the hot North American deserts, and ventifacts. Exceptionally long-lived, Larrea has the potential to preserve wind direction over centuries to millennia, shaped by the abrasive pruning of windward branches and the persistent training of leeward branches. Wind direction preserved in Larrea individuals and clones was mapped at 192 locations. Compared with wind data from three weather stations, Larrea vectors effectively reflect annual prevailing winds. Ventifacts measured at 24 locations record winds 10° more westerly than Larrea and appear to reflect the direction of the most erosive winds. Based on detailed mapping of local wind directions as preserved in Larrea, only the northern half of the Mission-Morongo Creek floodplain is likely to supply sand to protected U. inornata habitat in the Willow Hole ecological reserve.

  7. A Study on Maximum Wind Power Penetration Limit in Island Power System Considering High-Voltage Direct Current Interconnections

    Directory of Open Access Journals (Sweden)

    Minhan Yoon

    2015-12-01

    Full Text Available The variability and uncontrollability of wind power increases the difficulty for a power system operator to implement a wind power system with a high penetration rate. These are more serious factors to consider in small and isolated power systems since the system has small operating reserves and inertia to secure frequency and voltage. Typically, this difficulty can be reduced by interconnection with another robust power system using a controllable transmission system such as a high-voltage direct current (HVDC system. However, the reliability and stability constraints of a power system has to be performed according to the HVDC system implementation. In this paper, the method for calculation of maximum wind power penetration in an island supplied by a HVDC power system is presented, and the operational strategy of a HVDC system is proposed to secure the power system reliability and stability. The case study is performed for the Jeju Island power system in the Korean smart grid demonstration area.

  8. Direct power control of DFIG wind turbine systems based on an intelligent proportional-integral sliding mode control.

    Science.gov (United States)

    Li, Shanzhi; Wang, Haoping; Tian, Yang; Aitouch, Abdel; Klein, John

    2016-09-01

    This paper presents an intelligent proportional-integral sliding mode control (iPISMC) for direct power control of variable speed-constant frequency wind turbine system. This approach deals with optimal power production (in the maximum power point tracking sense) under several disturbance factors such as turbulent wind. This controller is made of two sub-components: (i) an intelligent proportional-integral module for online disturbance compensation and (ii) a sliding mode module for circumventing disturbance estimation errors. This iPISMC method has been tested on FAST/Simulink platform of a 5MW wind turbine system. The obtained results demonstrate that the proposed iPISMC method outperforms the classical PI and intelligent proportional-integral control (iPI) in terms of both active power and response time. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

  9. Advanced control of direct-driven PMSG generator in wind turbine system

    Directory of Open Access Journals (Sweden)

    Gajewski Piotr

    2016-12-01

    Full Text Available The paper presents the advanced control system of the wind energy conversion with a variable speed wind turbine. The considered system consists of a wind turbine with the permanent magnet synchronous generator (PMSG, machine side converter (MSC, grid side converter (GSC and control circuits. The mathematical models of a wind turbine system, the PMSG generator and converters have been described. The control algorithms of the converter systems based on the methods of vector control have been applied. In the advanced control system of the machine side converter the optimal MPPT control method has been used. Additionally the pitch control scheme is included in order to achieve the limitation of maximum power and to prevent mechanical damage of the wind turbine. In the control system of the grid side converter the control of active and reactive power has been applied with the application of Voltage Oriented Control (VOC. The performance of the considered wind energy system has been studied by digital simulation. The results of simulation studies confirmed the good effectiveness of the considered wind turbine system and very good performance of the proposed methods of vector control and control systems.

  10. Canadian Estimate of Bird Mortality Due to Collisions and Direct Habitat Loss Associated with Wind Turbine Developments

    Directory of Open Access Journals (Sweden)

    J. Ryan. Zimmerling

    2013-12-01

    Full Text Available We estimated impacts on birds from the development and operation of wind turbines in Canada considering both mortality due to collisions and loss of nesting habitat. We estimated collision mortality using data from carcass searches for 43 wind farms, incorporating correction factors for scavenger removal, searcher efficiency, and carcasses that fell beyond the area searched. On average, 8.2 ± 1.4 birds (95% C.I. were killed per turbine per year at these sites, although the numbers at individual wind farms varied from 0 - 26.9 birds per turbine per year. Based on 2955 installed turbines (the number installed in Canada by December 2011, an estimated 23,300 birds (95% C.I. 20,000 - 28,300 would be killed from collisions with turbines each year. We estimated direct habitat loss based on data from 32 wind farms in Canada. On average, total habitat loss per turbine was 1.23 ha, which corresponds to an estimated total habitat loss due to wind farms nationwide of 3635 ha. Based on published estimates of nest density, this could represent habitat for ~5700 nests of all species. Assuming nearby habitats are saturated, and 2 adults displaced per nest site, effects of direct habitat loss are less than that of direct mortality. Installed wind capacity is growing rapidly, and is predicted to increase more than 10-fold over the next 10-15 years, which could lead to direct mortality of approximately 233,000 birds / year, and displacement of 57,000 pairs. Despite concerns about the impacts of biased correction factors on the accuracy of mortality estimates, these values are likely much lower than those from collisions with some other anthropogenic sources such as windows, vehicles, or towers, or habitat loss due to many other forms of development. Species composition data suggest that < 0.2% of the population of any species is currently affected by mortality or displacement from wind turbine development. Therefore, population level impacts are unlikely

  11. Tidal analysis of Met rocket wind data

    Science.gov (United States)

    Bedinger, J. F.; Constantinides, E.

    1976-01-01

    A method of analyzing Met Rocket wind data is described. Modern tidal theory and specialized analytical techniques were used to resolve specific tidal modes and prevailing components in observed wind data. A representation of the wind which is continuous in both space and time was formulated. Such a representation allows direct comparison with theory, allows the derivation of other quantities such as temperature and pressure which in turn may be compared with observed values, and allows the formation of a wind model which extends over a broader range of space and time. Significant diurnal tidal modes with wavelengths of 10 and 7 km were present in the data and were resolved by the analytical technique.

  12. Comparing Pulsed Doppler LIDAR with SODAR and Direct Measurements for Wind Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Kelley, N. D.; Jonkman, B. J.; Scott, G. N.; Pichugina, Y. L.

    2007-07-01

    There is a pressing need for good wind-speed measurements at greater and greater heights to assess the availability of the resource in terms of power production and to identify any frequently occurring atmospheric structural characteristics that may create turbulence that impacts the operational reliability and lifetime of wind turbines and their components. In this paper, we summarize the results of a short study that compares the relative accuracies of wind speeds derived from a high-resolution pulsed Doppler LIDAR operated by the National Oceanic and Atmospheric Administration (NOAA) and a midrange Doppler SODAR with wind speeds measured by four levels of tower-based sonic anemometry up to a height of 116 m.

  13. Ancillary Frequency Control of Direct Drive Full-Scale Converter Based Wind Power Plants

    DEFF Research Database (Denmark)

    Hu, Weihao; Su, Chi; Fang, Jiakun

    2013-01-01

    emulation, primary frequency control and secondary frequency control, are proposed in order to improve the frequency stability of power systems. The modified IEEE 39-bus test system with a large-scale wind power penetration is chosen as the studied power system. Simulation results show that the proposed......This paper presents a simulation model of a wind power plant based on a MW-level variable speed wind turbine with a full-scale back-to-back power converter developed in the simulation tool of DIgSILENT Power Factory. Three different kinds of ancillary frequency control strategies, namely inertia...... control strategies are effective means for providing ancillary frequency control of variable speed wind turbines with full-scale back-to-back power converters....

  14. A Direct Comparison of Passive Polarimetry and Scatterometry Under Low- and High-Wind Conditions

    National Research Council Canada - National Science Library

    Swift, Calvin

    1997-01-01

    The University of Massachusetts Microwave Remote Sensing Laboratory (MIRSL) gathered coincident active and passive measurements of the ocean surface from the NASA Wallops P3 during the Ocean Wind Imaging (OWI) Experiment...

  15. Direct Embedding of Fiber-Optical Load Sensors into Wind Turbine Blades

    DEFF Research Database (Denmark)

    Glavind, Lars; Buggy, Stephen; Olesen, Ib S.

    Long Period Gratings were embedded into the adhesive utilized in the matrix of a wind turbine blade. The LPGs were subsequently subjected to temperature-testing in order to assess their performance, which illustrates good embedding capabilities....

  16. The influence of spatial effects on wind power revenues under direct marketing rules

    International Nuclear Information System (INIS)

    Grothe, Oliver; Müsgens, Felix

    2013-01-01

    In many countries, investments in renewable technologies have been accelerated by fixed feed-in tariffs for electricity from renewable energy sources (RES). While fixed tariffs accomplish this purpose, they lack incentives to align the RES production with price signals. Today, the intermittency of most RES increases the volatility of electricity prices and makes balancing supply and demand more complicated. Therefore, support schemes for RES have to be modified. Recently, Germany launched a scheme which gives wind power operators the monthly choice to either receive a fixed tariff or to risk a – subsidized – access to the wholesale electricity market. This paper quantifies revenues of wind turbines under this new subsidy and analyzes whether, when and where producers may profit. We find that the position of the wind turbine within the country significantly influences revenues in terms of EUR/MWh. The results are important for wind farm operators deciding whether electricity should be sold in the fixed feed-in tariff or in the wholesale market. However, no location is persistently, i.e., in every calendar month of the year, above the average. This limits the effect of the new subsidy scheme on investment locations and long term improvements in the aggregated wind feed-in profile. - Highlights: • Germany couples feed-in tariff for renewable energies to hourly market prices. • Analysis of position of wind turbines on relative revenues in EUR/MW. • Quantification of locational effect for policy makers and investors

  17. Current direction, benthic organisms, temperature, and wind direction data from moored current meter casts in the Gulf of Mexico during the Brine Disposal project, 22 September 1977 - 30 November 1978 (NODC Accession 7900110)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, benthic organisms, temperature, and wind direction data were collected using moored current meter casts in the Gulf of Mexico from September 22,...

  18. Wind direction/velocity and current direction/velocity data from current meter casts in a world wide distribution from 1970-12-06 to 1991-10-01 (NODC Accession 9700218)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Wind direction/velocity and current direction/velocity data were collected using current meter casts in a world wide distribution from December 6, 1970 to October 1,...

  19. A 225 kW Direct Driven PM Generator Adapted to a Vertical Axis Wind Turbine

    Directory of Open Access Journals (Sweden)

    S. Eriksson

    2011-01-01

    Full Text Available A unique direct driven permanent magnet synchronous generator has been designed and constructed. Results from simulations as well as from the first experimental tests are presented. The generator has been specifically designed to be directly driven by a vertical axis wind turbine and has an unusually low reactance. Generators for wind turbines with full variable speed should maintain a high efficiency for the whole operational regime. Furthermore, for this application, requirements are placed on high generator torque capability for the whole operational regime. These issues are elaborated in the paper and studied through simulations. It is shown that the generator fulfils the expectations. An electrical control can effectively substitute a mechanical pitch control. Furthermore, results from measurements of magnetic flux density in the airgap and no load voltage coincide with simulations. The electromagnetic simulations of the generator are performed by using an electromagnetic model solved in a finite element environment.

  20. Direct Torque Control in presence of Current sensor failure in Variable Speed Wind System: Effect analysis, detection and control reconfiguration

    Directory of Open Access Journals (Sweden)

    A. J. Arbi

    2008-03-01

    Full Text Available This paper presents a study of current sensor failure in a Direct Torque Control applied to a Double Fed Induction Generator based Variable Speed Wind System. The effect of scaling and offset current sensor errors is discussed through sensibility analysis. A control reconfiguration is then proposed to remedy this sensor failure. Simulation results emphasize the good performances of the proposed current sensor fault tolerant control

  1. Directional Bias of TAO Daily Buoy Wind Vectors in the Central Equatorial Pacific Ocean from November 2008 to January 2010

    Directory of Open Access Journals (Sweden)

    Ge Peng

    2014-07-01

    Full Text Available This article documents a systematic bias in surface wind directions between the TAO buoy measurements at 0°, 170°W and the ECMWF analysis and forecasts. This bias was of the order 10° and persisted from November 2008 to January 2010, which was consistent with a post-recovery calibration drift in the anemometer vane. Unfortunately, the calibration drift was too time-variant to be used to correct the data so the quality flag for this deployment was adjusted to reflect low data quality. The primary purpose of this paper is to inform users in the modelling and remote-sensing community about this systematic, persistent wind directional bias, which will allow users to make an educated decision on using the data and be aware of its potential impact to their downstream product quality. The uncovering of this bias and its source demonstrates the importance of continuous scientific oversight and effective user-data provider communication in stewarding scientific data. It also suggests the need for improvement in the ability of buoy data quality control procedures of the TAO and ECMWF systems to detect future wind directional systematic biases such as the one described here.

  2. Power control for direct-driven permanent magnet wind generator system with battery storage.

    Science.gov (United States)

    Guang, Chu Xiao; Ying, Kong

    2014-01-01

    The objective of this paper is to construct a wind generator system (WGS) loss model that addresses the loss of the wind turbine and the generator. It aims to optimize the maximum effective output power and turbine speed. Given that the wind generator system has inertia and is nonlinear, the dynamic model of the wind generator system takes the advantage of the duty of the Buck converter and employs feedback linearization to design the optimized turbine speed tracking controller and the load power controller. According to that, this paper proposes a dual-mode dynamic coordination strategy based on the auxiliary load to reduce the influence of mode conversion on the lifetime of the battery. Optimized speed and power rapid tracking as well as the reduction of redundant power during mode conversion have gone through the test based on a 5 kW wind generator system test platform. The generator output power as the capture target has also been proved to be efficient.

  3. Power Control for Direct-Driven Permanent Magnet Wind Generator System with Battery Storage

    Science.gov (United States)

    Guang, Chu Xiao; Ying, Kong

    2014-01-01

    The objective of this paper is to construct a wind generator system (WGS) loss model that addresses the loss of the wind turbine and the generator. It aims to optimize the maximum effective output power and turbine speed. Given that the wind generator system has inertia and is nonlinear, the dynamic model of the wind generator system takes the advantage of the duty of the Buck converter and employs feedback linearization to design the optimized turbine speed tracking controller and the load power controller. According to that, this paper proposes a dual-mode dynamic coordination strategy based on the auxiliary load to reduce the influence of mode conversion on the lifetime of the battery. Optimized speed and power rapid tracking as well as the reduction of redundant power during mode conversion have gone through the test based on a 5 kW wind generator system test platform. The generator output power as the capture target has also been proved to be efficient. PMID:25050405

  4. Overview of FACTS devices for wind power plants directly connected to the transmission network

    DEFF Research Database (Denmark)

    Adamczyk, Andrzej Grzegorz; Teodorescu, Remus; Rodriguez, Pedro

    2010-01-01

    of the electrical network with high wind energy penetration might be compromised. For this reason transmission system operators (TSO) impose more stringent connection requirements on the wind power plant (WPP) owners. On the other hand flexible AC transmission systems (FACTS) devices offer enhancement of grid...... stability and can facilitate grid code compliance for WPP. In this paper state-of-the-art in FACTS for WPPs with AC connection is given. FACTS devices with their properties are described. HVDC, which in literature is also often recognized as FACTS device, is out of this paper scope. Academic and industrial...

  5. Direct load control for electricity supply and demand matching : increasing reliability of wind energy

    NARCIS (Netherlands)

    Hoeve ten, Marieke

    2009-01-01

    In Sweden as well as in The Netherlands energy policy is increasingly aiming at extending the use of renew-able sources. In accordance with the targets of the European Union, both countries have formulated national targets for the year 2020. For wind ener

  6. Composite materials for wind energy applications: micromechanical modeling and future directions

    DEFF Research Database (Denmark)

    Mishnaevsky, Leon

    2012-01-01

    The strength and reliability of wind turbine blades depend on the properties, mechanical behavior and strengths of the material components (glass or carbon fibers and polymer matrix), and the interaction between them under loading. In this paper, ideas, methods and concepts of micromechanical...

  7. Airfoil and blade optimization for a direct-drive, permanent magnet wind generator

    Energy Technology Data Exchange (ETDEWEB)

    Dini, P. [Carleton College, Northfield, MN (United States); Bayly, E. [World Power Technologies, Inc., Duluth, MN (United States)

    1996-12-31

    A new blade is designed for a small, variable-speed wind turbine by relying on available theoretical design and analysis methods. The performance predictions are compared to field test measurements and are found to be optimistic. This feedback sheds light on the interpretation of the theoretical results and is used to refine the design method. 9 refs., 10 figs.

  8. Granger causality estimate of information flow in temperature fields is consistent with wind direction

    Czech Academy of Sciences Publication Activity Database

    Jajcay, Nikola; Hlinka, Jaroslav; Hartman, David; Paluš, Milan

    2014-01-01

    Roč. 16, - (2014), EGU2014-12768 ISSN 1607-7962. [EGU General Assembly /11./. 27.04.2014-02.05.2014, Vienna] Institutional support: RVO:67985807 Keywords : Granger causality * climate * information flow * surface air temperature * wind Subject RIV: BB - Applied Statistics, Operational Research

  9. Improved direct torque control of an induction generator used in a wind conversion system connected to the grid.

    Science.gov (United States)

    Abdelli, Radia; Rekioua, Djamila; Rekioua, Toufik; Tounzi, Abdelmounaïm

    2013-07-01

    This paper presents a modulated hysteresis direct torque control (MHDTC) applied to an induction generator (IG) used in wind energy conversion systems (WECs) connected to the electrical grid through a back-to-back converter. The principle of this strategy consists in superposing to the torque reference a triangular signal, as in the PWM strategy, with the desired switching frequency. This new modulated reference is compared to the estimated torque by using a hysteresis controller as in the classical direct torque control (DTC). The aim of this new approach is to lead to a constant frequency and low THD in grid current with a unit power factor and a minimum voltage variation despite the wind variation. To highlight the effectiveness of the proposed method, a comparison was made with classical DTC and field oriented control method (FOC). The obtained simulation results, with a variable wind profile, show an adequate dynamic of the conversion system using the proposed method compared to the classical approaches. Copyright © 2013 ISA. Published by Elsevier Ltd. All rights reserved.

  10. Hot solar-wind helium: direct evidence for local heating by Alfvén-cyclotron dissipation.

    Science.gov (United States)

    Kasper, J C; Lazarus, A J; Gary, S P

    2008-12-31

    A study of solar-wind hydrogen and helium temperature observations collected by the Wind spacecraft offers compelling evidence of heating by an Alfvén-cyclotron dissipation mechanism. Observations are sorted by the rate of Coulomb interactions, or collisional age, in the plasma and the differential flow between the two species. We show that helium is preferentially heated perpendicular to the magnetic field direction by more than a factor of 6 when the flow between the species is small relative to the Alfvén wave speed and collisions are infrequent. These signatures are consistent with predictions of dissipation in the presence of multiple ion species. We also report an unexpected result: observations of efficient heating of helium parallel to the magnetic field for large differential flow relative to the sound speed.

  11. Topology Comparison of Superconducting Generators for 10-MW Direct-Drive Wind Turbines: Cost of Energy Based

    DEFF Research Database (Denmark)

    Liu, Dong; Polinder, Henk; Abrahamsen, Asger Bech

    2017-01-01

    This paper aims at finding feasible electromagnetic designs of superconducting synchronous generators (SCSGs) for a 10-MW direct-drive wind turbine. Since a lower levelized cost of energy (LCoE) increases the feasibility of SCSGs in this application, 12 generator topologies are compared regarding...... their LCoE in a simplified form of levelized equipment cost of energy (LCoE$_{\\text{eq}}$). MgB$_2$ wires are employed in the field winding. Based on the current unit cost and critical current density capability of the MgB $_2$ wire at 20 K, the topologies with more iron have a much lower LCo...... having the most iron in the core are the most promising for both now and the long term. If low weight is required, the topologies with more nonmagnetic cores should be considered....

  12. Accuracy of National Weather Service wind-direction forecasts at Macon and Augusta, Georgia

    Science.gov (United States)

    Leonidas G. Lavdas

    1997-01-01

    National Weather Service wind forecasts and observations over a nine-year period (1985 to 1993) were analyzed to determine the usefulness of these forecasts for forestry smoke management. Data from Macon, GA indicated that forecasts were accurate to within plus or minus 22.5E about 38 percent of the time. When a wider plus or minus 67.5E window was used, accuracy...

  13. Direct Reuse of Rare Earth Permanent Magnets - Wind Turbine Generator Case Study

    DEFF Research Database (Denmark)

    Högberg, Stig; Pedersen, Thomas Stigsberg; Bendixen, Flemming Buus

    2016-01-01

    A novel recycling strategy, direct reuse, for rare earth permanent magnets were investigated in this article. Direct reuse uses small, unit-cell (segmented) magnets to replace the normal solid pole configuration, which is not directly reusable due its unique shape and size. The unit-cell magnets...

  14. Tower Winds - Cape Kennedy

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Digitized data taken from Wind Gust Charts. Record contains hourly wind directions and speed with a peak wind recorded at the end of each day. Sorted by: station,...

  15. Sand Drift Potential by Wind in Shileh Plain of Sistan

    Directory of Open Access Journals (Sweden)

    S. Poormand

    2016-02-01

    Full Text Available Introduction: Wind erosion is one of the most important factors in desert environments. Prevailing winds can shift sand dunes and affect their accumulation and morphology. Also, wind regime determines the direction of sand dune mobility in different ways. Therefore, the wind regime, frequency, direction and velocity are supposed to be the most important factors to form the morphology of sand dunes. Wind energy and changes in different directions (wind regime have large impacts on the morphology, maintenance and transformation of wind features. Having a global knowledge of the magnitude of aeolian processes, we can assess the powerful impact of sand dune mobility on residential areas and infrastructures. The most important factors including the frequency, magnitude and directional mobility of aeolian processes have a very important effect on the entrainment and form of sand dunes. Materials and Methods: To understand and identify the wind erosion regions, wind regime is a useful way since there is a strong correlation between wind regimes and sand dune morphology and structure. Sand rose and wind rose are assumed to be easy, fast and most accurate methods for the identification of wind erosion. Wind regimes processes have been studied by many researchers who believed that investigating wind regimes and sand dune mobility gives a measure of drift potential. Drift potential is a measure of the sand-moving capability by wind; derived from reduction of surface-wind data through a weighting equation. To predict drift potential, wind velocity and direction data from meteorological synoptic stations were used. Regarding the estimation of sand transport rate by wind, many formulas exist such as Bagnold, Kawamura, and Lattau. Also, many software applications have been suggested. However, among these formulas, Fryberger’s is the best and has been widely used since 1979. Results and Discussion: The aim of this study was to analyze wind velocities and

  16. The physical phenomena associated with stator winding insulation condition as detected by the ramped direct high-voltage method

    Science.gov (United States)

    Rux, Lorelynn Mary

    Deregulation of the electric utility industry has increased the need to monitor the state of powerplant equipment, such as critical generators and motors, to improve availability and reduce life cycle costs via condition-based maintenance. To achieve these goals, nondestructive condition assessment and diagnostic tests are necessary to evaluate the quality and condition of a machine's stator winding insulation system. Periodic tests are generally conducted to monitor insulation aging, diagnose problems, or provide some assurance that the winding has a minimum level of electrical strength. The basic principles of insulation testing are presented herein, and the physical mechanisms that affect the current versus voltage response are described. A stator winding insulation model was developed based on this theoretical foundation for use in understanding and analyzing the macroscopic behavior of complex insulation phenomena. A comprehensive, controlled laboratory experiment was conducted on a set of stator coils that were deliberately manufactured with and without insulation defects. Specific defects were chosen to represent the types of insulation problems typically encountered during manufacture or as a result of in-service aging, and included lack of resin cure, loosely-applied insulating tapes, internal conductive contamination, reduced density of the groundwall insulation, and thermal cycling damage. Results are presented from a series of electrical tests conducted on the coil specimens to compare the effectiveness of various test methods in detecting the different insulation problems. The tests included insulation resistance, polarization index, ramped direct voltage, dissipation factor, dielectric spectroscopy, partial discharge, and recovery voltage measurements. Dielectric principles and testing experience obtained during this investigation were applied to a collection of test results obtained by the author from in-service machines during the past ten years

  17. Prevailing Torque Locking Feature in Threaded Fasteners Using Anaerobic Adhesive

    Science.gov (United States)

    Hernandez, Alan; Hess, Daniel P.

    2016-01-01

    This paper presents results from tests to assess the use of anaerobic adhesive for providing a prevailing torque locking feature in threaded fasteners. Test procedures are developed and tests are performed on three fastener materials, four anaerobic adhesives, and both unseated assembly conditions. Five to ten samples are tested for each combination. Tests for initial use, reuse without additional adhesive, and reuse with additional adhesive are performed for all samples. A 48-hour cure time was used for all initial use and reuse tests. Test data are presented as removal torque versus removal angle with the specification required prevailing torque range added for performance assessment. Percent specification pass rates for the all combinations of fastener material, adhesive, and assembly condition are tabulated and reveal use of anaerobic adhesive as a prevailing torque locking feature is viable. Although not every possible fastener material and anaerobic adhesive combination provides prevailing torque values within specification, any combination can be assessed using the test procedures presented. Reuse without additional anaerobic adhesive generally provides some prevailing torque, and in some cases within specification. Reuse with additional adhesive often provides comparable removal torque data as in initial use.

  18. Design of a monolithic Michelson interferometer for fringe-imaging in a near-field, UV, direct detection Doppler wind lidar

    OpenAIRE

    Herbst, Jonas; Vrancken, Patrick

    2016-01-01

    The low-biased, fast, airborne, short-range, and range-resolved determination of atmospheric wind speeds plays a key role in wake vortex and turbulence mitigation strategies and would improve flight safety, comfort, and economy. In this work, a concept for an airborne, UV, direct-detection Doppler wind lidar receiver is presented. A monolithic, tilted, field-widened, fringe-imaging Michelson interferometer (FWFIMI) combines the Advantages of low angular sensitivity, high thermo-mecha...

  19. Spatio‐temporal analysis and modeling of short‐term wind power forecast errors

    DEFF Research Database (Denmark)

    Tastu, Julija; Pinson, Pierre; Kotwa, Ewelina

    2011-01-01

    for the spatio‐temporal dependencies observed in the wind generation field. However, it is intuitively expected that, owing to the inertia of meteorological forecasting systems, a forecast error made at a given point in space and time will be related to forecast errors at other points in space in the following...... of small size like western Denmark, significant correlation between the various zones is observed for time delays up to 5 h. Wind direction is shown to play a crucial role, while the effect of wind speed is more complex. Nonlinear models permitting capture of the interdependence structure of wind power...... period. The existence of such underlying correlation patterns is demonstrated and analyzed in this paper, considering the case‐study of western Denmark. The effects of prevailing wind speed and direction on autocorrelation and cross‐correlation patterns are thoroughly described. For a flat terrain region...

  20. Overview of condition monitoring and operation control of electric power conversion systems in direct-drive wind turbines under faults

    Science.gov (United States)

    Huang, Shoudao; Wu, Xuan; Liu, Xiao; Gao, Jian; He, Yunze

    2017-09-01

    Electric power conversion system (EPCS), which consists of a generator and power converter, is one of the most important subsystems in a direct-drive wind turbine (DD-WT). However, this component accounts for the most failures (approximately 60% of the total number) in the entire DD-WT system according to statistical data. To improve the reliability of EPCSs and reduce the operation and maintenance cost of DD-WTs, numerous researchers have studied condition monitoring (CM) and fault diagnostics (FD). Numerous CM and FD techniques, which have respective advantages and disadvantages, have emerged. This paper provides an overview of the CM, FD, and operation control of EPCSs in DD-WTs under faults. After introducing the functional principle and structure of EPCS, this survey discusses the common failures in wind generators and power converters; briefly reviewed CM and FD methods and operation control of these generators and power converters under faults; and discussed the grid voltage faults related to EPCSs in DD-WTs. These theories and their related technical concepts are systematically discussed. Finally, predicted development trends are presented. The paper provides a valuable reference for developing service quality evaluation methods and fault operation control systems to achieve high-performance and high-intelligence DD-WTs.

  1. Load-Direction-Derived Support Structures for Wind Turbines: A Lattice Tower Concept and Preparations for Future Certifications: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Jonkman, Jason [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Damiani, Rick R [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Struve, Achim [University of Applied Sciences Flensburg; Faber, Torsten [University of Applied Sciences Flensburg; Ummenhofer, Thomas [Karlsruhe Institute of Technology

    2017-11-07

    The call for more cost-effective and environmentally friendly tower concepts is motivated by tower costs [1] and tower CO2-emission contributions [2], which are high relative to the whole wind turbine system. The proposed rotatable tower concept with yaw bearing at the bottom instead of the top of the tower will provide beneficial economic and environmental impacts to the turbine system. This wind alignment capability indicates a load-direction-derived tower design. By combining this approach with a lattice concept, large material and cost savings for the tower can be achieved. This paper presents a way to analyze and verify the proposed design through aero-servo-elastic simulations, which make future certifications of rotatable tower concepts viable. For this reason, the state-of-the-art, open-source lattice-tower finite-element-method (FEM) module SubDyn [10], developed by the National Renewable Energy Laboratory, has been modified to account for arbitrary member cross-sections. Required changes in the beam element stiffness and mass matrix formulation took place according to an energy method [13]. All validated adaptions will be usable within the aero-servo-elastic simulation framework FAST and are also beneficial for other nonrotatable lattice structures.

  2. 77 FR 24941 - Vantage Wind Energy LLC; Order Accepting Updated Market Power Analysis and Providing Direction on...

    Science.gov (United States)

    2012-04-26

    .... 1. In this order, the Commission accepts an updated market power analysis filed by Vantage Wind.... Background 3. On December 20, 2010, Vantage Wind filed an updated market power analysis in compliance with... power analysis filed by Puget Sound Energy, Inc. (Puget).\\4\\ \\3\\ See Vantage Wind Energy LLC, Docket No...

  3. The Study of Fuzzy Proportional Integral Controllers Based on Improved Particle Swarm Optimization for Permanent Magnet Direct Drive Wind Turbine Converters

    Directory of Open Access Journals (Sweden)

    Yancai Xiao

    2016-05-01

    Full Text Available In order to meet the requirements of high precision and fast response of permanent magnet direct drive (PMDD wind turbines, this paper proposes a fuzzy proportional integral (PI controller associated with a new control strategy for wind turbine converters. The purpose of the control strategy is to achieve the global optimization for the quantization factors, ke and kec, and scale factors, kup and kui, of the fuzzy PI controller by an improved particle swarm optimization (PSO method. Thus the advantages of the rapidity of the improved PSO and the robustness of the fuzzy controller can be fully applied in the control process. By conducting simulations for 2 MW PMDD wind turbines with Matlab/Simulink, the performance of the fuzzy PI controller based on the improved PSO is demonstrated to be obviously better than that of the PI controller or the fuzzy PI controller without using the improved PSO under the situation when the wind speed changes suddenly.

  4. A comparison between two optimized TFPM geometries for 5 MW direct-drive wind turbines

    DEFF Research Database (Denmark)

    Nica, Florin Valentin Traian; Ritchie, Ewen; Leban, Krisztina Monika

    2013-01-01

    for the industry. The approach presented in this paper focuses on a reduction in mass of active materials, which constitute the generator, because the price of the machine is in direct relation with the amount of materials used for the construction. This strategy is applied for two types of TFPM geometries...... in order to asses which behaves better when subjected to optimization and which provides the best result. In order to obtain the mass of active materials the entire analytical design has to be covered, making the analytical design to behave as a cost function for the optimization program. The innovation...

  5. Ensemble using different Planetary Boundary Layer schemes in WRF model for wind speed and direction prediction over Apulia region

    Science.gov (United States)

    Tateo, Andrea; Marcello Miglietta, Mario; Fedele, Francesca; Menegotto, Micaela; Monaco, Alfonso; Bellotti, Roberto

    2017-04-01

    The Weather Research and Forecasting mesoscale model (WRF) was used to simulate hourly 10 m wind speed and direction over the city of Taranto, Apulia region (south-eastern Italy). This area is characterized by a large industrial complex including the largest European steel plant and is subject to a Regional Air Quality Recovery Plan. This plan constrains industries in the area to reduce by 10 % the mean daily emissions by diffuse and point sources during specific meteorological conditions named wind days. According to the Recovery Plan, the Regional Environmental Agency ARPA-PUGLIA is responsible for forecasting these specific meteorological conditions with 72 h in advance and possibly issue the early warning. In particular, an accurate wind simulation is required. Unfortunately, numerical weather prediction models suffer from errors, especially for what concerns near-surface fields. These errors depend primarily on uncertainties in the initial and boundary conditions provided by global models and secondly on the model formulation, in particular the physical parametrizations used to represent processes such as turbulence, radiation exchange, cumulus and microphysics. In our work, we tried to compensate for the latter limitation by using different Planetary Boundary Layer (PBL) parameterization schemes. Five combinations of PBL and Surface Layer (SL) schemes were considered. Simulations are implemented in a real-time configuration since our intention is to analyze the same configuration implemented by ARPA-PUGLIA for operational runs; the validation is focused over a time range extending from 49 to 72 h with hourly time resolution. The assessment of the performance was computed by comparing the WRF model output with ground data measured at a weather monitoring station in Taranto, near the steel plant. After the analysis of the simulations performed with different PBL schemes, both simple (e.g. average) and more complex post-processing methods (e.g. weighted average

  6. An Enhanced Three-Level Voltage Switching State Scheme for Direct Torque Controlled Open End Winding Induction Motor

    Science.gov (United States)

    Kunisetti, V. Praveen Kumar; Thippiripati, Vinay Kumar

    2018-01-01

    Open End Winding Induction Motors (OEWIM) are popular for electric vehicles, ship propulsion applications due to less DC link voltage. Electric vehicles, ship propulsions require ripple free torque. In this article, an enhanced three-level voltage switching state scheme for direct torque controlled OEWIM drive is implemented to reduce torque and flux ripples. The limitations of conventional Direct Torque Control (DTC) are: possible problems during low speeds and starting, it operates with variable switching frequency due to hysteresis controllers and produces higher torque and flux ripple. The proposed DTC scheme can abate the problems of conventional DTC with an enhanced voltage switching state scheme. The three-level inversion was obtained by operating inverters with equal DC-link voltages and it produces 18 voltage space vectors. These 18 vectors are divided into low and high frequencies of operation based on rotor speed. The hardware results prove the validity of proposed DTC scheme during steady-state and transients. From simulation and experimental results, proposed DTC scheme gives less torque and flux ripples on comparison to two-level DTC. The proposed DTC is implemented using dSPACE DS-1104 control board interface with MATLAB/SIMULINK-RTI model.

  7. Economic feasibility analysis of a wind farm in Caldas da Rainha, Portugal

    Energy Technology Data Exchange (ETDEWEB)

    de Oliveira, Wagner Sousa; Fernandes, Antonio Jorge [Department of Economics, Management and Industrial Engineering, University of Aveiro & Campus Universitario de Santiago, 3810-193 Aveiro (Portugal)

    2012-07-01

    This paper presents the technical and economical feasibility of a wind farm. The method is applied to a potential wind farm site located in Caldas da Rainha, Portugal. The site is considered on technical and economical parameters for the complete plant and its running costs. For technical consideration wind speed, prevailing wind direction, and temperature measurements are performed by using RETScreen Climate Database and Retscreen Product Database. The economic and financial evaluation of the wind farm is made by the software RETScreen(reg. sign) International Clean Energy Project Analysis and the indicators calculated are WACC, NPV, IRR, SPB, DPB, TLCC, BCR, LCOE, RR and UPAC. The sensitivity analysis backs up the findings through the scenarios developed (Current, S1, S2 and S3).

  8. Effect of Virtual Reality Exposure and Aural Stimuli on Eye Contact, Directional Focus, and Focus of Attention of Novice Wind Band Conductors

    Science.gov (United States)

    Orman, Evelyn K.

    2016-01-01

    This study examined the effects of virtual reality immersion with audio on eye contact, directional focus and focus of attention for novice wind band conductors. Participants (N = 34) included a control group (n = 12) and two virtual reality groups with (n = 10) and without (n = 12) head tracking. Participants completed conducting/score study…

  9. Enhanced Control for a Direct-driven Permanent Synchronous Generator Wind-power Generation System with Flywheel Energy Storage Unit Under Unbalanced Grid Fault

    DEFF Research Database (Denmark)

    Yao, Jun; Zhou, Te; Hu, Weihao

    2015-01-01

    This article presents an enhanced control strategy for a direct-driven permanent synchronous generator based wind-power generation system with a flywheel energy storage unit. The behaviors of the direct-driven permanent magnet synchronous generator system with a flywheel energy storage unit under......, the DC-link voltage oscillations can be effectively suppressed during the unbalanced grid fault by controlling the flywheel energy storage unit. Furthermore, a proportional–integral-resonant controller is designed for the flywheel motor to eliminate the oscillations in the DC-link voltage. Finally......, the proposed coordinated control strategy for the direct-driven permanent magnet synchronous generator system with a flywheel energy storage unit has been validated by the simulation results of a 1-MW direct-driven permanent magnet synchronous generator wind power generation system with a flywheel energy...

  10. The electric wind of Venus: A global and persistent "polar wind"-like ambipolar electric field sufficient for the direct escape of heavy ionospheric ions

    Science.gov (United States)

    Collinson, Glyn A.; Frahm, Rudy A.; Glocer, Alex; Coates, Andrew J.; Grebowsky, Joseph M.; Barabash, Stas; Domagal-Goldman, Shawn D.; Fedorov, Andrei; Futaana, Yoshifumi; Gilbert, Lin K.; Khazanov, George; Nordheim, Tom A.; Mitchell, David; Moore, Thomas E.; Peterson, William K.; Winningham, John D.; Zhang, Tielong L.

    2016-06-01

    Understanding what processes govern atmospheric escape and the loss of planetary water is of paramount importance for understanding how life in the universe can exist. One mechanism thought to be important at all planets is an "ambipolar" electric field that helps ions overcome gravity. We report the discovery and first quantitative extraterrestrial measurements of such a field at the planet Venus. Unexpectedly, despite comparable gravity, we show the field to be five times stronger than in Earth's similar ionosphere. Contrary to our understanding, Venus would still lose heavy ions (including oxygen and all water-group species) to space, even if there were no stripping by the solar wind. We therefore find that it is possible for planets to lose heavy ions to space entirely through electric forces in their ionospheres and such an "electric wind" must be considered when studying the evolution and potential habitability of any planet in any star system.

  11. The Electric Wind of Venus: A global and persistent "polar wind" like ambipolar electric field sufficient for the direct escape of heavy ionospheric ions

    Science.gov (United States)

    Collinson, G.; Frahm, R.; Glocer, A.; Coates, A. J.; Grebowsky, J. M.; Barbash, S.; Fedorov, A.; Futaana, Y.; Gilbert, L.; Khazanov, G. V.; Domagal-Goldman, S. D.; Nordheim, T.; Mitchell, D. L.; Moore, T. E.; Peterson, W.; Winningham, D.; Zhang, T.

    2016-12-01

    Understanding what processes govern atmospheric escape and the loss of planetary water is of paramount importance for understanding how life in the universe can exist. One mechanism thought to be important at all planets is an "ambipolar" electric field that helps ions overcome gravity. We report the discovery and first quantitative extraterrestrial measurements of such a field at the planet Venus. Unexpectedly, despite comparable gravity, we show the field to be five times stronger than in Earth's similar ionosphere. Contrary to our understanding, Venus would still lose heavy ions (including oxygen and all water-group species) to space, even if there were no stripping by the solar wind. We therefore find it is possible for planets to lose heavy ions to space entirely through electric forces in their ionospheres, and such an "electric wind" must be considered when studying the evolution and potential habitability of any planet in any star system

  12. The Electric Wind of Venus: A Global and Persistent Polar Wind -Like Ambipolar Electric Field Sufficient for the Direct Escape of Heavy Ionospheric Ions

    Science.gov (United States)

    Collinson, Glyn A.; Frahm, Rudy A.; Glocer, Alex; Coates, Andrew J.; Grebowsky, Joseph M.; Barabash, Stas; Domagal-Goldman, Shawn D.; Federov, Andrei; Futaana, Yoshifumi; Gilbert, Lin K.; hide

    2016-01-01

    Understanding what processes govern atmospheric escape and the loss of planetary water is of paramount importance for understanding how life in the universe can exist. One mechanism thought to be important at all planets is an ambipolar electric field that helps ions overcome gravity. We report the discovery and first quantitative extraterrestrial measurements of such a field at the planet Venus. Unexpectedly, despite comparable gravity, we show the field to be five times stronger than in Earths similar ionosphere. Contrary to our understanding, Venus would still lose heavy ions (including oxygen and all water-group species) to space, even if there were no stripping by the solar wind. We therefore find that it is possible for planets to lose heavy ions to space entirely through electric forces in their ionospheres and such an electric wind must be considered when studying the evolution and potential habitability of any planet in any star system.

  13. Operating capability as a PQ/PV node of a direct-drive wind turbine based on a permanent magnet synchronous generator

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, L.M.; Garcia, C.A. [Department of Electrical Engineering, University of Cadiz, EPS Algeciras, Avda. Ramon Puyol s/n,11202 Algeciras (Cadiz) (Spain); Jurado, F. [Department of Electrical Engineering, University of Jaen, EPS Linares, C/ Alfonso X n . 28, 23700 Linares (Jaen) (Spain)

    2010-06-15

    This paper describes the modelling and control system of a direct-drive PMSG wind turbine for effective active and reactive power generation control and voltage control at the grid connection point. This study focuses on the maximum power capability of the wind turbine, which is limited by its generator and power converter. The ability of this model and control strategy are assessed by means of simulations and discussed at length. The results of our study show that a PMSG wind turbine is able to actively participate in grid operation because it can independently control active and reactive power production (operating as a PQ node) or the active power and voltage at the connection node (operating as a PV node). (author)

  14. Assessment of Global Wind Energy Resource Utilization Potential

    Science.gov (United States)

    Ma, M.; He, B.; Guan, Y.; Zhang, H.; Song, S.

    2017-09-01

    Development of wind energy resource (WER) is a key to deal with climate change and energy structure adjustment. A crucial issue is to obtain the distribution and variability of WER, and mine the suitable location to exploit it. In this paper, a multicriteria evaluation (MCE) model is constructed by integrating resource richness and stability, utilization value and trend of resource, natural environment with weights. The global resource richness is assessed through wind power density (WPD) and multi-level wind speed. The utilizable value of resource is assessed by the frequency of effective wind. The resource stability is assessed by the coefficient of variation of WPD and the frequency of prevailing wind direction. Regression slope of long time series WPD is used to assess the trend of WER. All of the resource evaluation indicators are derived from the atmospheric reanalysis data ERA-Interim with spatial resolution 0.125°. The natural environment factors mainly refer to slope and land-use suitability, which are derived from multi-resolution terrain elevation data 2010 (GMTED 2010) and GlobalCover2009. Besides, the global WER utilization potential map is produced, which shows most high potential regions are located in north of Africa. Additionally, by verifying that 22.22 % and 48.8 9% operational wind farms fall on medium-high and high potential regions respectively, the result can provide a basis for the macroscopic siting of wind farm.

  15. Electronic Power Transformer Control Strategy in Wind Energy Conversion Systems for Low Voltage Ride-through Capability Enhancement of Directly Driven Wind Turbines with Permanent Magnet Synchronous Generators (D-PMSGs

    Directory of Open Access Journals (Sweden)

    Hui Huang

    2014-11-01

    Full Text Available This paper investigates the use of an Electronic Power Transformer (EPT incorporated with an energy storage system to smooth the wind power fluctuations and enhance the low voltage ride-through (LVRT capability of directly driven wind turbines with permanent magnet synchronous generators (D-PMSGs. The decoupled control schemes of the system, including the grid side converter control scheme, generator side converter control scheme and the control scheme of the energy storage system, are presented in detail. Under normal operating conditions, the energy storage system absorbs the high frequency component of the D-PMSG output power to smooth the wind power fluctuations. Under grid fault conditions, the energy storage system absorbs the redundant power, which could not be transferred to the grid by the EPT, to help the D-PMSG to ride through low voltage conditions. This coordinated control strategy is validated by simulation studies using MATLAB/Simulink. With the proposed control strategy, the output wind power quality is improved and the D-PMSG can ride through severe grid fault conditions.

  16. Airborne direct-detection and coherent wind lidar measurements over the North Atlantic in 2015 supporting ESA's aeolus mission

    Science.gov (United States)

    Marksteiner, Uwe; Reitebuch, Oliver; Lemmerz, Christian; Lux, Oliver; Rahm, Stephan; Witschas, Benjamin; Schäfler, Andreas; Emmitt, Dave; Greco, Steve; Kavaya, Michael J.; Gentry, Bruce; Neely, Ryan R.; Kendall, Emma; Schüttemeyer, Dirk

    2018-04-01

    The launch of the Aeolus mission by the European Space Agency (ESA) is planned for 2018. The satellite will carry the first wind lidar in space, ALADIN (Atmospheric Laser Doppler INstrument). Its prototype instrument, the ALADIN Airborne Demonstrator (A2D), was deployed during several airborne campaigns aiming at the validation of the measurement principle and optimization of algorithms. In 2015, flights of two aircraft from DLR & NASA provided the chance to compare parallel wind measurements from four airborne wind lidars for the first time.

  17. Wind and Yaw correlation

    DEFF Research Database (Denmark)

    Federici, Paolo; Kock, Carsten Weber

    The report describes measurements carried out on a given turbine and period. The measurements are carried out in accordance to Ref. [1]. A comparison between wind speed and wind direction on the met mast and nacelle wind speed and yaw direction is made in accordance to Ref. [2] and the results...... are presented on graphs and in a table....

  18. Wind and Yaw correlation

    DEFF Research Database (Denmark)

    Federici, Paolo; Kock, Carsten Weber

    The report describes measurements carried out on a given turbine and period. The measurements are carried out in accordance to Ref. [1]. A comparison between wind speed and wind direction on the met mast and nacelle wind speed and yaw direction is made in accordance to Ref. [2] and the results...

  19. Wind power. [electricity generation

    Science.gov (United States)

    Savino, J. M.

    1975-01-01

    A historical background on windmill use, the nature of wind, wind conversion system technology and requirements, the economics of wind power and comparisons with alternative systems, data needs, technology development needs, and an implementation plan for wind energy are presented. Considerable progress took place during the 1950's. Most of the modern windmills feature a wind turbine electricity generator located directly at the top of their rotor towers.

  20. Farmers prevailing perception profiles regarding GM crops: A classification proposal.

    Science.gov (United States)

    Almeida, Carla; Massarani, Luisa

    2018-04-01

    Genetically modified organisms have been at the centre of a major public controversy, involving different interests and actors. While much attention has been devoted to consumer views on genetically modified food, there have been few attempts to understand the perceptions of genetically modified technology among farmers. By investigating perceptions of genetically modified organisms among Brazilian farmers, we intend to contribute towards filling this gap and thereby add the views of this stakeholder group to the genetically modified debate. A comparative analysis of our data and data from other studies indicate there is a complex variety of views on genetically modified organisms among farmers. Despite this diversity, we found variations in such views occur within limited parameters, concerned principally with expectations or concrete experiences regarding the advantages of genetically modified crops, perceptions of risks associated with them, and ethical questions they raise. We then propose a classification of prevailing profiles to represent the spectrum of perceptions of genetically modified organisms among farmers.

  1. Development of an Offshore Direct-Drive Wind Turbine Model by Using a Flexible Multibody Simulation (Poster)

    Energy Technology Data Exchange (ETDEWEB)

    Bergua, R.; Jove, J.; Campbell, J.; Guo, Y.; Van Dam, J.

    2014-05-01

    Modern wind turbines are complex, highly-coupled systems. The dynamic interaction between various components is especially pronounced for multi-megawatt wind turbines. As a result, design process is generally split in several phases. First step consists of creating a global aero-elastic model that includes essential dynamics of structural components using the minimum-possible number of degrees of freedom (d.o.f.). The most important simplifications concern drivetrain and rotor-nacelle assembly (RNA). This approach has been shown valid for several wind turbine configurations. Nevertheless, with increasing size of wind turbines, any simplified design approach must be validated. The present work deals with the comparison and validation of the two modeling approaches for directdrive offshore wind turbines. ARNA/drivetrain model idealized as collection of lumped masses and springs is compared to a detailed Finite Element Method (FEM) based model. The comparison between models focuses on dynamic loads concerning drivetrain system. The comparison is performed in several operational conditions in order to explore the range of validity of the simplified model. Finally, the paper proposes a numerical-based workflow to assess the validity of simplified models of RNA/drivetrain in an aero-elastic global WT model.

  2. Wind barriers suppress fugitive dust and soil-derived airborne particles in arid regions

    Energy Technology Data Exchange (ETDEWEB)

    Grantz, D.A.; Vaughn, D.L. [Univ. of California, Parlier, CA (United States). Kearney Agricultural Center; Farber, R.J. [SoCal Edison, Rosemead, CA (United States). Environmental Research Div.; Kim, B. [South Coast Air Quality Management District, Diamond Bar, CA (United States); Ashbaugh, L. [Univ. of California, Davis, CA (United States). Crocker Nuclear Lab.; Van Curen, T. [California Air Resources Board, Sacramento, CA (United States); Campbell, R. [Antelope Valley Resources Conservation District, Lancaster, CA (United States)

    1998-07-01

    Areas of abandoned agricultural land in the Antelope Valley, western Mojave (high) desert of California have proven in the previous studies to be recalcitrant to conventional tillage and revegetation strategies designed to suppress wind erosion of soil and transport of sediment and fugitive dust. These areas represented a continuing source of drifting sand and of coarse and respirable suspended particulate matter. The traditional techniques failed because furrows collapsed and the water holding capacity of the overburden was too low to support seed germination and transplant survival. In this study a variety of wind barriers were evaluated for suppression of sediment transport. Airborne particles were measured with an array of coarse particle samplers at heights of 0.2, 1.0, and 2.0 m above the soil surface. Discrete artificial wind barriers, consisting of widely spaced roughness elements were effective in suppressing fugitive emissions. Wind fences established along the leeward edge of an area of blowing sand, perpendicular to the prevailing wind, significantly decreased fugitive emissions. Control was greatest and precision of the measurements was highest under high wind conditions. These techniques provide rapid and effective suppression of fugitive emissions of soil-derived particles under conditions that resist conventional tillage and revegetation techniques. A simple, indirect procedure for determining local wind velocity erosion thresholds requiring only sampling of wind run and suspended particulate mass compared favorably with direct measurement of saltation as a function of wind velocity.

  3. Program to determine space vehicle response to wind turbulence

    Science.gov (United States)

    Wilkening, H. D.

    1972-01-01

    Computer program was developed as prelaunch wind monitoring tool for Saturn 5 vehicle. Program accounts for characteristic wind changes including turbulence power spectral density, wind shear, peak wind velocity, altitude, and wind direction using stored variational statistics.

  4. Wind-induced flow velocity effects on nutrient concentrations at Eastern Bay of Lake Taihu, China.

    Science.gov (United States)

    Jalil, Abdul; Li, Yiping; Du, Wei; Wang, Jianwei; Gao, Xiaomeng; Wang, Wencai; Acharya, Kumud

    2017-07-01

    Shallow lakes are highly sensitive to respond internal nutrient loading due to wind-induced flow velocity effects. Wind-induced flow velocity effects on nutrient suspension were investigated at a long narrow bay of large shallow Lake Taihu, the third largest freshwater lake in China. Wind-induced reverse/compensation flow and consistent flow field probabilities at vertical column of the water were measured. The probabilities between the wind field and the flow velocities provided a strong correlation at the surface (80.6%) and the bottom (65.1%) layers of water profile. Vertical flow velocity profile analysis provided the evidence of delay response time to wind field at the bottom layer of lake water. Strong wind field generated by the west (W) and west-north-west (WNW) winds produced displaced water movements in opposite directions to the prevailing flow field. An exponential correlation was observed between the current velocities of the surface and the bottom layers while considering wind speed as a control factor. A linear model was developed to correlate the wind field-induced flow velocity impacts on nutrient concentration at the surface and bottom layers. Results showed that dominant wind directions (ENE, E, and ESE) had a maximum nutrient resuspension contribution (nutrient resuspension potential) of 34.7 and 43.6% at the surface and the bottom profile layers, respectively. Total suspended solids (TSS), total nitrogen (TN), and total phosphorus (TP) average concentrations were 6.38, 1.5, and 0.03 mg/L during our field experiment at Eastern Bay of Lake Taihu. Overall, wind-induced low-to-moderate hydrodynamic disturbances contributed more in nutrient resuspension at Eastern Bay of Lake Taihu. The present study can be used to understand the linkage between wind-induced flow velocities and nutrient concentrations for shallow lakes (with uniform morphology and deep margins) water quality management and to develop further models.

  5. 77 FR 34854 - Prevailing Rate Systems; Special Wage Schedules for Nonappropriated Fund Automotive Mechanics

    Science.gov (United States)

    2012-06-12

    ...-AM63 Prevailing Rate Systems; Special Wage Schedules for Nonappropriated Fund Automotive Mechanics... for the Department of Defense's (DOD's) nonappropriated fund (NAF) automotive mechanics. These special... practice for compensating NAF automotive mechanics with current prevailing pay practices in the private...

  6. System efficiency of a tap transformer based grid connection topology applied on a direct driven generator for wind power.

    Science.gov (United States)

    Apelfröjd, Senad; Eriksson, Sandra

    2014-01-01

    Results from experiments on a tap transformer based grid connection system for a variable speed vertical axis wind turbine are presented. The tap transformer based system topology consists of a passive diode rectifier, DC-link, IGBT inverter, LCL-filter, and tap transformer. Full range variable speed operation is enabled by using the different step-up ratios of a tap transformer. Simulations using MATLAB/Simulink have been performed in order to study the behavior of the system. A full experimental set up of the system has been used in the laboratory study, where a clone of the on-site generator was driven by an induction motor and the system was connected to a resistive load to better evaluate the performance. Furthermore, the system is run and evaluated for realistic wind speeds and variable speed operation. For a more complete picture of the system performance, a case study using real site Weibull parameters is done, comparing different tap selection options. The results show high system efficiency at nominal power and an increase in overall power output for full tap operation in comparison with the base case, a standard transformer. In addition, the loss distribution at different wind speeds is shown, which highlights the dominant losses at low and high wind speeds. Finally, means for further increasing the overall system efficiency are proposed.

  7. System Efficiency of a Tap Transformer Based Grid Connection Topology Applied on a Direct Driven Generator for Wind Power

    Science.gov (United States)

    2014-01-01

    Results from experiments on a tap transformer based grid connection system for a variable speed vertical axis wind turbine are presented. The tap transformer based system topology consists of a passive diode rectifier, DC-link, IGBT inverter, LCL-filter, and tap transformer. Full range variable speed operation is enabled by using the different step-up ratios of a tap transformer. Simulations using MATLAB/Simulink have been performed in order to study the behavior of the system. A full experimental set up of the system has been used in the laboratory study, where a clone of the on-site generator was driven by an induction motor and the system was connected to a resistive load to better evaluate the performance. Furthermore, the system is run and evaluated for realistic wind speeds and variable speed operation. For a more complete picture of the system performance, a case study using real site Weibull parameters is done, comparing different tap selection options. The results show high system efficiency at nominal power and an increase in overall power output for full tap operation in comparison with the base case, a standard transformer. In addition, the loss distribution at different wind speeds is shown, which highlights the dominant losses at low and high wind speeds. Finally, means for further increasing the overall system efficiency are proposed. PMID:25258733

  8. System Efficiency of a Tap Transformer Based Grid Connection Topology Applied on a Direct Driven Generator for Wind Power

    Directory of Open Access Journals (Sweden)

    Senad Apelfröjd

    2014-01-01

    Full Text Available Results from experiments on a tap transformer based grid connection system for a variable speed vertical axis wind turbine are presented. The tap transformer based system topology consists of a passive diode rectifier, DC-link, IGBT inverter, LCL-filter, and tap transformer. Full range variable speed operation is enabled by using the different step-up ratios of a tap transformer. Simulations using MATLAB/Simulink have been performed in order to study the behavior of the system. A full experimental set up of the system has been used in the laboratory study, where a clone of the on-site generator was driven by an induction motor and the system was connected to a resistive load to better evaluate the performance. Furthermore, the system is run and evaluated for realistic wind speeds and variable speed operation. For a more complete picture of the system performance, a case study using real site Weibull parameters is done, comparing different tap selection options. The results show high system efficiency at nominal power and an increase in overall power output for full tap operation in comparison with the base case, a standard transformer. In addition, the loss distribution at different wind speeds is shown, which highlights the dominant losses at low and high wind speeds. Finally, means for further increasing the overall system efficiency are proposed.

  9. The shadow effect of large wind farms: measurements, data analysis and modelling. Summary report[Final summary report

    Energy Technology Data Exchange (ETDEWEB)

    Frandsen, Steen; Barthelmie, R.; Rathmann, O.; Joergensen, Hans E.; Badger, J.; Hansen, Kurt; Ott, S.; Rethore, P.-E.; Larsen, Soeren E.; Jensen, Leo E.

    2007-07-15

    It was the goal of the project by means of data from the demonstration wind farms Horns Rev and Nysted, analyses of these data and modelling to facilitate prediction of the power losses from a wind farm should a new wind farm be built upwind relative to the prevailing wind direction. Or conversely, predict with adequate accuracy the production of a new wind farm built downwind of an existing wind farm. The project should be seen in the perspective of the two existing demonstration wind farms that extend 5-10 km in each direction. In order to e.g. use the existing electrical infrastructure it may be appropriate to build new wind farms rather close to the existing wind farms. A relevant question is therefore how far away new wind farms must be placed to avoid too large power losses. Measurements have been carried out for several years at the two sites, and databases have been prepared. The databases one for each site include production and operational statistics for the wind turbines and statistics for the meteorological measurements carries out in the vicinity of the wind farms. Several different modelling activities were carried out, which intentionally to some extent are redundant. Thus, if different modelling efforts results in comparable results, the quality of the models will be tested outside the physical range where data are available. All project participants find that the project has been immensely successful. The main achievements of the project are: 1) Measurements were carried out at the Nysted and Horns Rev demonstration wind farms for several years. Doing so included design, installation and operation of the measurement system 2) A data base was built from the incoming data. The data have been organized to facilitate verification of the models developed as part of the project 3) 6-7 different models have been developed and compared. 4) Approximately 20 journal and conference papers have resulted directly from the project (au)

  10. Design of a monolithic Michelson interferometer for fringe imaging in a near-field, UV, direct-detection Doppler wind lidar.

    Science.gov (United States)

    Herbst, Jonas; Vrancken, Patrick

    2016-09-01

    The low-biased, fast, airborne, short-range, and range-resolved determination of atmospheric wind speeds plays a key role in wake vortex and turbulence mitigation strategies and would improve flight safety, comfort, and economy. In this work, a concept for an airborne, UV, direct-detection Doppler wind lidar receiver is presented. A monolithic, tilted, field-widened, fringe-imaging Michelson interferometer (FWFIMI) combines the advantages of low angular sensitivity, high thermo-mechanical stability, independence of the specific atmospheric conditions, and potential for fast data evaluation. Design and integration of the FWFIMI into a lidar receiver concept are described. Simulations help to evaluate the receiver design and prospect sufficient performance under different atmospheric conditions.

  11. The role of wind field induced flow velocities in destratification and hypoxia reduction at Meiling Bay of large shallow Lake Taihu, China.

    Science.gov (United States)

    Jalil, Abdul; Li, Yiping; Du, Wei; Wang, Wencai; Wang, Jianwei; Gao, Xiaomeng; Khan, Hafiz Osama Sarwar; Pan, Baozhu; Acharya, Kumud

    2018-01-01

    Wind induced flow velocity patterns and associated thermal destratification can drive to hypoxia reduction in large shallow lakes. The effects of wind induced hydrodynamic changes on destratification and hypoxia reduction were investigated at the Meiling bay (N 31° 22' 56.4″, E 120° 9' 38.3″) of Lake Taihu, China. Vertical flow velocity profile analysis showed surface flow velocities consistency with the wind field and lower flow velocity profiles were also consistent (but with delay response time) when the wind speed was higher than 6.2 m/s. Wind field and temperature found the control parameters for hypoxia reduction and for water quality conditions at the surface and bottom profiles of lake. The critical temperature for hypoxia reduction at the surface and the bottom profile was ≤24.1C° (below which hypoxic conditions were found reduced). Strong prevailing wind field (onshore wind directions ESE, SE, SSE and E, wind speed ranges of 2.4-9.1 m/s) reduced the temperature (22C° to 24.1C°) caused reduction of hypoxia at the near surface with a rise in water levels whereas, low to medium prevailing wind field did not supported destratification which increased temperature resulting in increased hypoxia. Non-prevailing wind directions (offshore) were not found supportive for the reduction of hypoxia in study area due to less variable wind field. Daytime wind field found more variable (as compared to night time) which increased the thermal destratification during daytime and found supportive for destratification and hypoxia reduction. The second order exponential correlation found between surface temperature and Chlorophyll-a (R 2 : 0.2858, Adjusted R-square: 0.2144 RMSE: 4.395), Dissolved Oxygen (R 2 : 0.596, Adjusted R-square: 0.5942, RMSE: 0.3042) concentrations. The findings of the present study reveal the driving mechanism of wind induced thermal destratification and hypoxic conditions, which may further help to evaluate the wind role in eutrophication

  12. Genetics of Schizophrenia: Historical Insights and Prevailing Evidence.

    Science.gov (United States)

    van de Leemput, J; Hess, J L; Glatt, S J; Tsuang, M T

    2016-01-01

    Schizophrenia's (SZ's) heritability and familial transmission have been known for several decades; however, despite the clear evidence for a genetic component, it has been very difficult to pinpoint specific causative genes. Even so genetic studies have taught us a lot, even in the pregenomic era, about the molecular underpinnings and disease-relevant pathways. Recurring themes emerged revealing the involvement of neurodevelopmental processes, glutamate regulation, and immune system differential activation in SZ etiology. The recent emergence of epigenetic studies aimed at shedding light on the biological mechanisms underlying SZ has provided another layer of information in the investigation of gene and environment interactions. However, this epigenetic insight also brings forth another layer of complexity to the (epi)genomic landscape such as interactions between genetic variants, epigenetic marks-including cross-talk between DNA methylation and histone modification processes-, gene expression regulation, and environmental influences. In this review, we seek to synthesize perspectives, including limitations and obstacles yet to overcome, from genetic and epigenetic literature on SZ through a qualitative review of risk factors and prevailing hypotheses. Encouraged by the findings of both genetic and epigenetic studies to date, as well as the continued development of new technologies to collect and interpret large-scale studies, we are left with a positive outlook for the future of elucidating the molecular genetic mechanisms underlying SZ and other complex neuropsychiatric disorders. Copyright © 2016 Elsevier Inc. All rights reserved.

  13. Familiar units prevail over statistical cues in word segmentation.

    Science.gov (United States)

    Poulin-Charronnat, Bénédicte; Perruchet, Pierre; Tillmann, Barbara; Peereman, Ronald

    2017-09-01

    In language acquisition research, the prevailing position is that listeners exploit statistical cues, in particular transitional probabilities between syllables, to discover words of a language. However, other cues are also involved in word discovery. Assessing the weight learners give to these different cues leads to a better understanding of the processes underlying speech segmentation. The present study evaluated whether adult learners preferentially used known units or statistical cues for segmenting continuous speech. Before the exposure phase, participants were familiarized with part-words of a three-word artificial language. This design allowed the dissociation of the influence of statistical cues and familiar units, with statistical cues favoring word segmentation and familiar units favoring (nonoptimal) part-word segmentation. In Experiment 1, performance in a two-alternative forced choice (2AFC) task between words and part-words revealed part-word segmentation (even though part-words were less cohesive in terms of transitional probabilities and less frequent than words). By contrast, an unfamiliarized group exhibited word segmentation, as usually observed in standard conditions. Experiment 2 used a syllable-detection task to remove the likely contamination of performance by memory and strategy effects in the 2AFC task. Overall, the results suggest that familiar units overrode statistical cues, ultimately questioning the need for computation mechanisms of transitional probabilities (TPs) in natural language speech segmentation.

  14. Anywhere the Wind Blows does Really Matter

    Science.gov (United States)

    Montaldo, Nicola; Oren, Ram

    2014-05-01

    The variation of net ecosystem carbon exchange (NEE) has been explained at coarse scales with variation of forcing variables among climate regions and associated biomes, at the intermediate, mesoscale, with differences among dominating vegetation types and conditions, and at the misoscale with heterogeneity of the eddy covariance footprint properties. Wind is rarely considered in analysis of surface fluxes for its effects on periodic budgets of water and carbon. In many regions conditions change frequently between maritime and continental depending on wind velocity (VW) and direction. In these regions, water and carbon fluxes may respond to mesoscale weather patterns extending maritime influences far inland. Using eddy-covariance data from Sardinia, we show that daytime net carbon exchange (NEE) of a mixed pasture-woodland (grass-wild olive) ecosystem (Detto et al., 2006; Montaldo et al., 2008) increased with VW, especially during summer-dry conditions. As VW increased, the air, humidified over sea, remains relatively moist and cool to a greater distance inland, reaching only ~50 km during slow Saharan Sirocco wind but >160 km during mostly Mistral wind (4 m/s) from Continental Europe. A 30% lower vapor pressure deficit (D) associated with high VW (average 2 kPa at 4 m/s), allowed a 50% higher canopy stomatal conductance (gc) and, thus, photosynthesis. However, because gc and D have opposite effects on evapotranspiration (Ee), Ee was unaffected by VW. Thus, higher NEE during summertime Mistral reflects increased ecosystem water-use efficiency (We) and a departure from a costly carbon-water tradeoff. Yet many regions often experience high velocity winds, attention is typically focused on the capacity of strong winds to fan regional fires, threatening human habitation and natural habitats, and reducing Carbon storage (C), NEE and latent heat flux. However, depending on their origin, high velocity winds can bring continental air to the coast (e.g., Santa Ana winds

  15. Current direction, wind wave spectra, and other data from moored current meter casts and other instruments in the Gulf of Mexico during the Brine Disposal project, 1978-10-11 to 1980-03-19 (NODC Accession 8000368)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, wind wave spectra, and other data were collected using moored current meter casts and other instruments from the CAPT JACK and EXCELLENCE in the...

  16. Temperature, wind direction, and salinity data from moored current meter casts in the Gulf of Mexico during the Brine Disposal project, 01 December 1980 - 01 December 1980 (NODC Accession 8100457)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature, wind direction, and salinity data were collected using moored current meter casts in the Gulf of Mexico from December 1, 1980 to December 1, 1980. Data...

  17. Current direction, phytoplankton, zooplankton, wind wave spectra, and other data from moored current meter casts and other instruments in the Gulf of Mexico during the Brine Disposal project, 1981-02-07 to 1982-11-01 (NODC Accession 8300055)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, phytoplankton, zooplankton, wind wave spectra, and other data were collected using moored current meter casts and other instruments in the Gulf of...

  18. Current direction and wind wave spectra data from moored current meter casts in the Gulf of Mexico during the Brine Disposal project, 01 November 1980 - 01 November 1980 (NODC Accession 8100222)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current direction and wind wave spectra data were collected using moored current meter casts in the Gulf of Mexico from November 1, 1980 to November 1, 1980. Data...

  19. Current direction and wind wave spectra data from moored current meter casts in the Gulf of Mexico as part of the Brine Disposal project, 1977-02-02 to 1979-01-31 (NODC Accession 7900144)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, salinity, and wind wave spectra data were collected using moored current meter casts in the Gulf of Mexico from February 2, 1978 to January 31,...

  20. Current direction, benthic organisms, wind wave spectra data from moored current meter casts and other instruments in the Gulf of Mexico during the Brine Disposal project, 25 March 1977 - 01 February 1980 (NODC Accession 8000320)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, benthic organisms, wind wave spectra, and other data were collected using moored current meter casts in the Gulf of Mexico from March 25, 1977 to...

  1. Current direction and wind wave spectra data from moored current meter casts in the Gulf of Mexico as part of the Brine Disposal project, 1977-12-22 to 1978-10-31 (NODC Accession 7900023)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, temperature, and wind wave spectra data were collected using moored current meter casts in the Gulf of Mexico from December 22, 1977 to October...

  2. Temperature, wind direction, and salinity data from moored current meter casts in the Gulf of Mexico during the Brine Disposal project, 01 January 1981 - 01 January 1981 (NODC Accession 8100474)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature, wind direction, and salinity data were collected using moored current meter casts in the Gulf of Mexico from January 1, 1981 to January 1, 1981. Data...

  3. Current direction and wind wave spectra data from moored current meter casts in the Gulf of Mexico as part of the Brine Disposal project, 1977-12-22 to 1978-07-01 (NODC Accession 7900123)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, temperature, and wind wave spectra data were collected using moored current meter casts in the Gulf of Mexico from December 22, 1977 to October...

  4. Current direction, wind wave spectra, and CTD data from moored current meter and CTD casts in the North Atlantic Ocean from 1982-09-15 to 1983-09-15 (NODC Accession 8500148)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, wind wave spectra, and CTD data were collected using moored current meter and CTD casts in the Gulf of Mexico from September 3, 1982 to September...

  5. Current direction, zooplankton, wind wave spectra, benthic organisms, and other data from moored current meter casts and other instruments in the Gulf of Mexico during the Brine Disposal project, 18 October 1977 to 01 May 1979 (NODC Accession 7900270)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, zooplankton, benthic organisms, wind wave spectra, and other data were collected using moored current meter casts and other instruments in the...

  6. Current direction, benthic organisms, wind wave spectra, and other data from moored current meter casts and other instruments in the Gulf of Mexico during the Brine Disposal project, 1978-01-12 to 1980-06-01 (NODC Accession 8000465)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, benthic organisms, wind wave spectra, and other data were collected using moored current meter casts and other instruments from the CAPT JACK and...

  7. Current direction, wind wave spectra, phytoplankton, zooplankton, and other data from moored current meter casts and other instruments in the Gulf of Mexico during the Brine Disposal project, 1977-09-24 to 1981-08-31 (NODC Accession 8100681)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, chemical, phytoplankton, zooplankton, wind wave spectra, and other data were collected using moored current meter casts and other instruments in...

  8. Behavior of current sheets at directional magnetic discontinuities in the solar wind at 0.72 AU

    Czech Academy of Sciences Publication Activity Database

    Zhang, T. L.; Russell, C. T.; Zambelli, W.; Vörös, Zoltán; Wang, C.; Cao, J. B.; Jian l, L. K.; Strangeway, R. J.; Balikhin, M.; Baumjohann, W.; Delva, M.; Volwerk, M.; Glassmeier, K.; H.

    2008-01-01

    Roč. 35, č. 24 (2008), L24102/1-L24102/5 ISSN 0094-8276 Grant - others:Austrian Wissenschaftfonds(AT) P20131-N16; NNSFC(CN) 40628003; 973 Program(CN) 2006CB806305; NASA (US) NNG06GC62G Institutional research plan: CEZ:AV0Z30420517 Keywords : solar wind * current sheets * magnetic annihilation Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.959, year: 2008

  9. Combined free-stream disturbance measurements and receptivity studies in hypersonic wind tunnels by means of a slender wedge probe and direct numerical simulation

    Science.gov (United States)

    Wagner, Alexander; Schülein, Erich; Petervari, René; Hannemann, Klaus; Ali, Syed R. C.; Cerminara, Adriano; Sandham, Neil D.

    2018-05-01

    Combined free-stream disturbance measurements and receptivity studies in hypersonic wind tunnels were conducted by means of a slender wedge probe and direct numerical simulation. The study comprises comparative tunnel noise measurements at Mach 3, 6 and 7.4 in two Ludwieg tube facilities and a shock tunnel. Surface pressure fluctuations were measured over a wide range of frequencies and test conditions including harsh test environments not accessible to measurement techniques such as pitot probes and hot-wire anemometry. Quantitative results of the tunnel noise are provided in frequency ranges relevant for hypersonic boundary layer transition. In combination with the experimental studies, direct numerical simulations of the leading-edge receptivity to fast and slow acoustic waves were performed for the slender wedge probe at conditions corresponding to the experimental free-stream conditions. The receptivity to fast acoustic waves was found to be characterized by an early amplification of the induced fast mode. For slow acoustic waves an initial decay was found close to the leading edge. At all Mach numbers, and for all considered frequencies, the leading-edge receptivity to fast acoustic waves was found to be higher than the receptivity to slow acoustic waves. Further, the effect of inclination angles of the acoustic wave with respect to the flow direction was investigated. The combined numerical and experimental approach in the present study confirmed the previous suggestion that the slow acoustic wave is the dominant acoustic mode in noisy hypersonic wind tunnels.

  10. Device for the acquisition and visualization in real time of the velocity and direction of wind in a radiological post stage

    International Nuclear Information System (INIS)

    Ledo P, L.M.; Guibert G, R.; Dominguez L, O.; Alonso A, D.; Ramos V, E.O.

    2006-01-01

    The work shows the development, construction and post stage of a device dedicated to the acquisition and transmission in real time of the information on the behavior of the meteorological variables: velocity and wind direction. It is introduced for the first time in an observation position the automatic monitoring, in real time, using the tools that it offers the digitalisation of the information and the computation. The obtained data are registered in a PC, its are visualized appropriately and can be objects of later analysis. It was developed the application program Autoclima for such purpose. (Author)

  11. Wind energy

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    This chapter discusses the role wind energy may have in the energy future of the US. The topics discussed in the chapter include historical aspects of wind energy use, the wind energy resource, wind energy technology including intermediate-size and small wind turbines and intermittency of wind power, public attitudes toward wind power, and environmental, siting and land use issues

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

    Indian Academy of Sciences (India)

    The effectiveness of vegetation in reducing wind ... Wind erosion; roughness length; shear velocity ratio; shear stress ratio; roughness density; wind tunnel. J. Earth .... flow direction induced by its kinematic viscosity. An increase in shear stress causes a proportional increase in the height-dependent change in wind velocity.

  13. Effects of trade-wind strength and direction on the leeside circulations and rainfall of the island of Hawaii

    Science.gov (United States)

    Yang Yang; Yi-Leng Chen; Francis M. Fujioka

    2009-01-01

    The leeside circulations and weather of the island of Hawaii were studied from the fifth-generation Pennsylvania State University–NCAR Mesoscale Model (MM5) land surface model simulations for eight strong (∼7.9 m s−1) and eight weak (∼5.2 m s−1) trade-wind days and for five days with southeasterly trades (∼7.1 m s

  14. Analyzing SO2 concentrations and wind directions during a short monitoring campaign at a site far from the industrial pole of La Plata, Argentina.

    Science.gov (United States)

    Ratto, Gustavo; Videla, Fabian; Maronna, Ricardo

    2009-02-01

    This article presents and discusses SO2 air quality concentrations (ppbv) together with wind velocities and directions measurements carried out between September 1st and December 21st 2005 at a site located 8.5 km away from the Industrial Pole of La Plata area. As the city and its surroundings have no official monitoring network, the current work enlarges the air quality information available from the zone and sets some initial considerations to the future siting of monitoring stations. The statistical analysis of the data was performed using techniques of tests for outliers and trends, dissimilarity measures and robust regression. In relation to SO2 concentrations, low values were found during this short campaign considering daily averages (with a maximum of 8.5 ppbv) and hourly averages (with a maximum of 25.9 ppbv); World Health Organization guidelines were never surpassed. Nevertheless, a strong dependence between wind directions carrying air pollutants from the Industrial Pole and hourly concentration peaks were found. Due to low monthly SO2 concentrations and because a decreasing time trend was found, the authors propose, as an example, the implementation of an alternative discontinuous method to the continuous analyzer used in the current campaign. Our results state that sampling every 7 days at 13:00-13:59 hours (local time) would be enough to get representative values of the air quality. As a general remark it is possible to highlight that longer and systematic studies should be encouraged to confirm the seasonal wind pattern and to evaluate the air quality.

  15. Evaluation of wind farm efficiency and wind turbine wakes at the Nysted offshore wind farm

    DEFF Research Database (Denmark)

    Barthelmie, Rebecca Jane; Jensen, L.E.

    2010-01-01

    be quantified, albeit with relatively large uncertainty due to stochastic effects in the data. There is evidence of the ‘deep array effect’ in that wake losses in the centre of the wind farm are under-estimated by the wind farm model WAsP, although overall efficiency of the wind farm is well predicted due......Here, we quantify relationships between wind farm efficiency and wind speed, direction, turbulence and atmospheric stability using power output from the large offshore wind farm at Nysted in Denmark. Wake losses are, as expected, most strongly related to wind speed variations through the turbine...... thrust coefficient; with direction, atmospheric stability and turbulence as important second order effects. While the wind farm efficiency is highly dependent on the distribution of wind speeds and wind direction, it is shown that the impact of turbine spacing on wake losses and turbine efficiency can...

  16. Noise from wind turbines

    International Nuclear Information System (INIS)

    Andersen, B.; Jakobsen, J.

    1992-11-01

    Based on a previous project concerning the calculation of the amount of noise emanating from wind turbine arrays, this one examines the subject further by investigating whether there could be significant differences in the amount of noise made by individual wind turbines in an array, and whether the noise is transmitted in varying directions - so that when it is carried in the same direction as the wind blows it would appear to be louder. The aim was also to determine whether the previously used method of calculation lacked precision. It was found that differences in noise niveaux related to individual wind turbines were insignificant and that noise was not so loud when it was not borne in the direction of the wind. It was necessary to change the method of calculation as reckoning should include the influence of the terrain, wind velocity and distance. The measuring and calculation methods are exemplified and the resulting measurements are presented in detail. (AB)

  17. The Influence of Structural Morphology on the Efficiency of Building Integrated Wind Turbines (BIWT

    Directory of Open Access Journals (Sweden)

    Hassam Nasarullah Chaudhry

    2014-08-01

    Full Text Available A numerical investigation was carried out to determine the impact of structural morphology on the power generation capacity of building-integrated wind turbines. The performance of the turbines was analysed using the specifications of the Bahrain Trade Centre which was taken as the benchmark model, the results of which were compared against triangular, square and circular cross-sections of the same building. The three-dimensional Reynolds-Averaged Navier-Stokes (RANS equations along with the momentum and continuity equations were solved for obtaining the velocity and pressure field. Simulating a reference wind speed of 6 m/s, the findings from the study quantified an estimate power generation of 6.4 kW indicating a capacity factor of 2.9 % for the benchmark model. The square and circular configurations however determined greater capacity factors of 12.2 % and 19.9 %, recording an estimated power production capability of 26.9 kW and 35.1 kW and confirming the largest extraction of the incoming wind stream. The optimum cross-sectional configuration for installing wind turbines in high-rise buildings was the circular orientation as the average wind speed at the wind turbines was accelerated by 0.3 m/s resulting in an overall augmentation of 5 %. The results from this study therefore highlighted that circular building morphology is the most viable building orientation, particularly suited to regions with a dominant prevailing wind direction.

  18. 42 CFR 405.504 - Determining prevailing charges.

    Science.gov (United States)

    2010-10-01

    ... the direct-labor price components are adjusted by an annual percent change in a 10-year moving average... are net of the change in the 10-year moving average of output per man-hour to exclude changes in non...) Changes in general earnings levels of workers that are attributable to factors other than increases in...

  19. Mongolia wind resource assessment project

    International Nuclear Information System (INIS)

    Elliott, D.; Chadraa, B.; Natsagdorj, L.

    1998-01-01

    The development of detailed, regional wind-resource distributions and other pertinent wind resource characteristics (e.g., assessment maps and reliable estimates of seasonal, diurnal, and directional) is an important step in planning and accelerating the deployment of wind energy systems. This paper summarizes the approach and methods being used to conduct a wind energy resource assessment of Mongolia. The primary goals of this project are to develop a comprehensive wind energy resource atlas of Mongolia and to establish a wind measurement program in specific regions of Mongolia to identify prospective sites for wind energy projects and to help validate some of the wind resource estimates. The Mongolian wind resource atlas will include detailed, computerized wind power maps and other valuable wind resource characteristic information for the different regions of Mongolia

  20. Computational Analysis to Factor Wind into the Design of an Architectural Environment

    Directory of Open Access Journals (Sweden)

    Hassam Nasarullah Chaudhry

    2015-01-01

    Full Text Available The effect of wind distribution on the architectural domain of the Bahrain Trade Centre was numerically analysed using computational fluid dynamics (CFD. Using the numerical data, the power generation potential of the building-integrated wind turbines was determined in response to the prevailing wind direction. The three-dimensional Reynolds-averaged Navier-Stokes (RANS equations along with the momentum and continuity equations were solved for obtaining the velocity and pressure field. Simulating a reference wind speed of 6 m/s, the findings from the study quantified an estimate power generation of 6.4 kW indicating a capacity factor of 2.9% for the benchmark model. At the windward side of the building, it was observed that the layers of turbulence intensified in inverse proportion to the height of the building with an average value of 0.45 J/kg. The air velocity was found to gradually increase in direct proportion to the elevation with the turbine located at higher altitude receiving maximum exposure to incoming wind. This work highlighted the potential of using advanced computational fluid dynamics in order to factor wind into the design of any architectural environment.

  1. Some Wind Characteristics of Kahe Point, O’ahu and Vicinity

    Science.gov (United States)

    1988-08-01

    breeze circulation interaction with prevailing winds is found to be in good agreement with earlier numerical results of Estoque (1962). Hodographs...synoptic winds. Sea- breeze circulation interaction with prevailing winds is found to be in good agreement with earlier numerical results of Estoque ...extends eastward of site 129. Using a two-dimensional numerical model, Estoque (1962) showed that strongest vertical motions associated with the sea

  2. Wind: French revolutions

    International Nuclear Information System (INIS)

    Jones, C.

    2006-01-01

    Despite having the second best wind resources in Europe after the UK, the wind industry in France lags behind its European counterparts with just 6 W of installed wind capacity per person. The electricity market in France is dominated by the state-owned Electricite de France (EdF) and its nuclear power stations. However, smaller renewable generators are now in theory allowed access to the market and France has transposed the EU renewables directive into national law. The French governement has set a target of generating 10,000 MW of renewable capacity by 2010. The announcement of an increased feed-in tariff and the introduction of 'development zones' (ZDEs) which could allow fast-tracking of planning for wind projects are also expected to boost wind projects. But grid access and adminstrative burdens remain major barriers. In addition, French politicians and local authorities remain committed to nuclear, though encouraged by the European Commission, wind is beginning to gain acceptance; some 325 wind farms (representing 1557 MW of capacity) were approved between February 2004 and January 2005. France is now regarded by the international wind energy sector as a target market. One of France's leading independent wind developers and its only listed wind company, Theolia, is expected to be one of the major beneficiaries of the acceleration of activity in France, though other companies are keen to maximise the opportunities for wind. France currently has only one indigenous manufacturer of wind turbines, but foreign suppliers are winning orders

  3. Wind/water energy converter

    Science.gov (United States)

    Paulkovich, J.

    1979-01-01

    Device will convert wind, water, tidal or wave energy into electrical or mechanical energy. Is comprised of windmill-like paddles or blades synchronously geared to orient themselves to wind direction for optimum energy extraction.

  4. Wind tower service lift

    Science.gov (United States)

    Oliphant, David; Quilter, Jared; Andersen, Todd; Conroy, Thomas

    2011-09-13

    An apparatus used for maintaining a wind tower structure wherein the wind tower structure may have a plurality of legs and may be configured to support a wind turbine above the ground in a better position to interface with winds. The lift structure may be configured for carrying objects and have a guide system and drive system for mechanically communicating with a primary cable, rail or other first elongate member attached to the wind tower structure. The drive system and guide system may transmit forces that move the lift relative to the cable and thereby relative to the wind tower structure. A control interface may be included for controlling the amount and direction of the power into the guide system and drive system thereby causing the guide system and drive system to move the lift relative to said first elongate member such that said lift moves relative to said wind tower structure.

  5. Extreme winds in Denmark

    DEFF Research Database (Denmark)

    Kristensen, L.; Rathmann, O.; Hansen, S.O.

    2000-01-01

    ), Kegnaes (7 yr), Sprogo (20 yr), and Tystofte (16 yr). The measured data are wind speed, wind direction, temperature and pressure. The wind records are cleaned for terrain effects by means of WASP (Mortensew ct al., Technical Report I-666 (EN), Riso National Laboratory, 1993. Vol. 2. User's Guide......): assuming geostrophic balance, all the wind-velocity data are transformed to friction velocity u(*) and direction at standard conditions by means of the geostrophic drag law for neutral stratification. The basic wind velocity in 30 degrees sectors are obtained through ranking of the largest values...... of the friction velocity pressure pu(*)(2)/2 taken once every two months. The main conclusion is that the basic wind velocity is significantly larger at the west coast of Jutland (25 +/- 1 m/s) than at any of the other sites (22 +/- 1 m/s). These results are in agreement with those obtained by Jensen and Franck...

  6. Concepts of spirituality prevailing among undergraduate medical students in Delhi

    Directory of Open Access Journals (Sweden)

    Shantanu Sharma

    2017-01-01

    Full Text Available Background: Spirituality is considered one of the determinants of health. Various studies have documented its role in the management of psychological illnesses such as schizophrenia, and anxiety disorders. Doctors often lack skills to do spiritual assessment of the patients. Aim: The current study was conducted among the 1st year undergraduate medical students to find out their ideas and thoughts about spirituality using self-administered questionnaire. Methodology: This was a college based cross sectional study wherein 168 students were interviewed using semistructured, self administered questionnaire. Ethical clearance was obtained from Institutional ethical committee.Results: Most of the students (93.5% believed in spirituality, but only about half (49% of them had complete knowledge about it. Only psychological disorders and chronic diseases were labeled by students who need spirituality as a modality of treatment. Girls linked spirituality with God more than boys. A formal training in spirituality is not essential according to 43% of the subjects. Conclusion: The undergraduates need to understand the importance of this dimension of health. A mere gain in knowledge about spiritual strength available in some of the textbooks would not be able to orient doctors sufficiently to apply it in their practice. Future Direction: Skill building and practicing the culture of spiritual counseling among health workers is the need of hour.

  7. Prevailing Trends in Haptic Feedback Simulation for Minimally Invasive Surgery.

    Science.gov (United States)

    Pinzon, David; Byrns, Simon; Zheng, Bin

    2016-08-01

    Background The amount of direct hand-tool-tissue interaction and feedback in minimally invasive surgery varies from being attenuated in laparoscopy to being completely absent in robotic minimally invasive surgery. The role of haptic feedback during surgical skill acquisition and its emphasis in training have been a constant source of controversy. This review discusses the major developments in haptic simulation as they relate to surgical performance and the current research questions that remain unanswered. Search Strategy An in-depth review of the literature was performed using PubMed. Results A total of 198 abstracts were returned based on our search criteria. Three major areas of research were identified, including advancements in 1 of the 4 components of haptic systems, evaluating the effectiveness of haptic integration in simulators, and improvements to haptic feedback in robotic surgery. Conclusions Force feedback is the best method for tissue identification in minimally invasive surgery and haptic feedback provides the greatest benefit to surgical novices in the early stages of their training. New technology has improved our ability to capture, playback and enhance to utility of haptic cues in simulated surgery. Future research should focus on deciphering how haptic training in surgical education can increase performance, safety, and improve training efficiency. © The Author(s) 2016.

  8. Long-Term Mean Wind Profiles Based on Similarity Theory

    DEFF Research Database (Denmark)

    Kelly, Mark C.; Gryning, Sven-Erik

    2010-01-01

    We provide general forms for long-term mean wind profiles from similarity-based wind profiles, beginning with a probabilistic adaptation of Monin–Obukhov similarity theory. We develop an analytical formulation for the stability distributions prevailing in the atmospheric surface layer, which...

  9. Wind Tunnel Measurements at LM Wind Power

    DEFF Research Database (Denmark)

    Bertagnolio, Franck

    2012-01-01

    The optimization of airfoil profiles specifically designed for wind turbine application was initiated in the late 80’s [67, 68, 30, 15]. The first attempts to reduce airfoil noise for wind turbines made use of airfoil trailing edge serration. Themodification of airfoil shapes targeted at noise...... reduction is more recent. An important effort was produced in this direction within the SIROCCO project. This latter work involved measurements on full size wind turbines and showed that trailing edge serration may proved a viable solution for mitigating wind turbine noise though it has not been implemented...... on commercial wind turbine yet. It should be mentioned here that the attenuation of turbulent inflow noise using wavy leading edge has recently been investigated [55], but this technique has still to be further validated for practical applications. In this paper, it is proposed to optimize an airfoil which...

  10. Assessment of ENSEMBLES regional climate models for the representation of monthly wind characteristics in the Aegean Sea (Greece): Mean and extremes analysis

    Science.gov (United States)

    Anagnostopoulou, Christina; Tolika, Konstantia; Tegoulias, Ioannis; Velikou, Kondylia; Vagenas, Christos

    2013-04-01

    The main scope of the present study is the assessment of the ability of three of the most updated regional climate models, developed under the frame of the European research project ENSEMBLES (http://www.ensembles-eu.org/), to simulate the wind characteristics in the Aegean Sea in Greece. The examined models are KNMI-RACMO2, MPI-MREMO, and ICTP - RegCM3. They all have the same spatial resolution (25x25km) and for their future projections they are using the A1B SRES emission scenarios. Their simulated wind data (speed and direction) were compared with observational data from several stations over the domain of study for a time period of 25 years, from 1980 to 2004 on a monthly basis. The primer data were available every three or six hours from which we computed the mean daily wind speed and the prevailing daily wind direction. It should be mentioned, that the comparison was made for the grid point that was the closest to each station over land. Moreover, the extreme speed values were also calculated both for the observational and the simulated data, in order to assess the ability of the models in capturing the most intense wind conditions. The first results of the study showed that the prevailing winds during the winter and spring months have a north - northeastern or a south - south western direction in most parts of the Aegean sea. The models under examination seem to capture quite satisfactorily this pattern as well as the general characteristics of the winds in this area. During summer, winds in the Aegean Sea have mainly north direction and the models have quite good agreement both in simulating this direction and the wind speed. Concerning the extreme wind speed (percentiles) it was found that for the stations in the northern Aegean all the models overestimate the extreme wind indices. For the eastern parts of the Aegean the KNMI and the MPI model underestimate the extreme wind speeds while on the other hand the ICTP model overestimates them. Finally for the

  11. Vertical axis wind turbine

    International Nuclear Information System (INIS)

    Obretenov, V.; Tsalov, T.; Chakarov, T.

    2012-01-01

    In recent years, the interest in wind turbines with vertical axis noticeably increased. They have some important advantages: low cost, relatively simple structure, reliable packaging system of wind aggregate long period during which require no maintenance, low noise, independence of wind direction, etc.. The relatively low efficiency, however, makes them applicable mainly for small facilities. The work presents a methodology and software for approximately aerodynamic design of wind turbines of this type, and also analyzed the possibility of improving the efficiency of their workflow

  12. Design of High-Efficiency and Low-Cost Six-Phase Permanent Magnet Synchronous Generator for Direct-Drive Small-Scale Wind Power Application

    Directory of Open Access Journals (Sweden)

    M. E. Moazzen

    2017-06-01

    Full Text Available Permanent magnet synchronous generators (PMSG have a huge potential for direct-drive wind power applications. Therefore, optimal design of these generators is necessary to maximize their efficiency and to reduce their manufacturing cost and total volume. In this paper, an optimal design of a six-phase 3.5 KW direct-drive PMSG to generate electricity for domestic needs is performed. The aim of optimal design is to reduce the manufacturing cost, losses and total volume of PMSG. To find the best design, single/multi-objective design optimization is carried out. Cuckoo optimization algorithm (COA is adopted to solve the optimization problem. Comparison between the results of the single-objective and multi-objective models shows that simultaneous optimization of manufacturing cost, losses and total volume leads to more suitable design for PMSG. Finally, finite-element method (FEM is employed to validate the optimal design, which show a good agreement between the theoretical work and simulation results.

  13. Wind Energy

    International Nuclear Information System (INIS)

    Rodriguez D, J.M.

    1998-01-01

    The general theory of the wind energy conversion systems is presented. The availability of the wind resource in Colombia and the ranges of the speed of the wind in those which is possible economically to use the wind turbines are described. It is continued with a description of the principal technological characteristics of the wind turbines and are split into wind power and wind-powered pumps; and its use in large quantities grouped in wind farms or in autonomous systems. Finally, its costs and its environmental impact are presented

  14. Marine wind data presentation using wind transition matrix

    Digital Repository Service at National Institute of Oceanography (India)

    Mascarenhas, A.J.; Gouveia, A.D.; Desai, R.G.P.

    depends upon the direction from which the wind is presently blowing. The percentage cumulative wind transition matrix of the order of 49 x 49 has been presented for the data obtainEd. by the wind monitoring system. These observations were obtained at a...

  15. Summertime wind climate in Yerevan: valley wind systems

    Science.gov (United States)

    Gevorgyan, Artur

    2017-03-01

    1992-2014 wind climatology analysis in Yerevan is presented with particular focus given to the summertime thermally induced valley wind systems. Persistence high winds are observed in Yerevan during July-August months when the study region is strongly affected by a heat-driven plain-plateau circulation. The local valley winds arrive in Yerevan in the evening hours, generally, from 1500 to 1800 UTC, leading to rapid enhancement of wind speeds and dramatic changes in wind direction. Valley-winds significantly impact the local climate of Yerevan, which is a densely populated city. These winds moderate evening temperatures after hot and dry weather conditions observed during summertime afternoons. On the other hand, valley winds result in significantly higher nocturnal temperatures and more frequent occurrence of warm nights (tn90p) in Yerevan due to stronger turbulent mixing of boundary layer preventing strong surface cooling and temperature drop in nighttime and morning hours. The applied WRF-ARW limited area model is able to simulate the key features of the observed spatial pattern of surface winds in Armenia associated with significant terrain channeling, wind curls, etc. By contrast, ECMWF EPS global model fails to capture mesoscale and local wind systems over Armenia. However, the results of statistical verification of surface winds in Yerevan showed that substantial biases are present in WRF 18-h wind forecasts, as well as, the temporal variability of observed surface winds is not reproduced adequately in WRF-ARW model.

  16. Cuticle Structure in Relation to Chemical Composition: Re-assessing the Prevailing Model.

    Science.gov (United States)

    Fernández, Victoria; Guzmán-Delgado, Paula; Graça, José; Santos, Sara; Gil, Luis

    2016-01-01

    The surface of most aerial plant organs is covered with a cuticle that provides protection against multiple stress factors including dehydration. Interest on the nature of this external layer dates back to the beginning of the 19th century and since then, several studies facilitated a better understanding of cuticular chemical composition and structure. The prevailing undertanding of the cuticle as a lipidic, hydrophobic layer which is independent from the epidermal cell wall underneath stems from the concept developed by Brongniart and von Mohl during the first half of the 19th century. Such early investigations on plant cuticles attempted to link chemical composition and structure with the existing technologies, and have not been directly challenged for decades. Beginning with a historical overview about the development of cuticular studies, this review is aimed at critically assessing the information available on cuticle chemical composition and structure, considering studies performed with cuticles and isolated cuticular chemical components. The concept of the cuticle as a lipid layer independent from the cell wall is subsequently challenged, based on the existing literature, and on new findings pointing toward the cell wall nature of this layer, also providing examples of different leaf cuticle structures. Finally, the need for a re-assessment of the chemical and structural nature of the plant cuticle is highlighted, considering its cell wall nature and variability among organs, species, developmental stages, and biotic and abiotic factors during plant growth.

  17. Wind Energy Systems

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Ma, Ke

    2017-01-01

    Wind power now represents a major and growing source of renewable energy. Large wind turbines (with capacities of up to 6-8 MW) are widely installed in power distribution networks. Increasing numbers of onshore and offshore wind farms, acting as power plants, are connected directly to power...... transmission networks at the scale of hundreds of megawatts. As its level of grid penetration has begun to increase dramatically, wind power is starting to have a significant impact on the operation of the modern grid system. Advanced power electronics technologies are being introduced to improve...... the characteristics of the wind turbines, and make them more suitable for integration into the power grid. Meanwhile, there are some emerging challenges that still need to be addressed. This paper provides an overview and discusses some trends in the power electronics technologies used for wind power generation...

  18. Wind Turbines Wake Aerodynamics

    DEFF Research Database (Denmark)

    Vermeer, L.; Sørensen, Jens Nørkær; Crespo, A.

    2003-01-01

    The aerodynamics of horizontal axis wind turbine wakes is studied. The contents is directed towards the physics of power extraction by wind turbines and reviews both the near and the far wake region. For the near wake, the survey is restricted to uniform, steady and parallel flow conditions......, thereby excluding wind shear, wind speed and rotor setting changes and yawed conditions. The emphasis is put on measurements in controlled conditions.For the far wake, the survey focusses on both single turbines and wind farm effects, and the experimental and numerical work are reviewed; the main interest...... is to study how the far wake decays downstream, in order to estimate the effect produced in downstream turbines.The article is further restricted to horizontal axis wind turbines and excludes all other types of turbines....

  19. Molecular-based mechanisms of Mendelian forms of salt-dependent hypertension: questioning the prevailing theory.

    Science.gov (United States)

    Kurtz, Theodore W; Dominiczak, Anna F; DiCarlo, Stephen E; Pravenec, Michal; Morris, R Curtis

    2015-05-01

    This critical review directly challenges the prevailing theory that a transient increase in cardiac output caused by genetically mediated increases in activity of the ENaC in the aldosterone sensitive distal nephron, or of the NCC in the distal convoluted tubule, accounts entirely for the hemodynamic initiation of all Mendelian forms of salt-dependent hypertension (Figure 1). The prevailing theory of how genetic mutations enable salt to hemodynamically initiate Mendelian forms of salt-dependent hypertension in humans (Figure 1) depends on the results of salt-loading studies of cardiac output and systemic vascular resistance in nongenetic models of hypertension that lack appropriate normal controls. The theory is inconsistent with the results of studies that include measurements of the initial hemodynamic changes induced by salt loading in normal, salt-resistant controls. The present analysis, which takes into account the results of salt-loading studies that include the requisite normal controls, indicates that mutation-induced increases in the renal tubular activity of ENaC or NCC that lead to transient increases in cardiac output will generally not be sufficient to enable increases in salt intake to initiate the increased BP that characterizes Mendelian forms of salt-dependent hypertension (Table). The present analysis also raises questions about whether mutation-dependent increases in renal tubular activity of ENaC or NCC are even necessary to account for increased risk for salt-dependent hypertension in most patients with such mutations. We propose that for the genetic alterations underlying Mendelian forms of salt-dependent hypertension to enable increases in salt intake to initiate the increased BP, they must often cause vasodysfunction, ie, an inability to normally vasodilate and decrease systemic vascular resistance in response to increases in salt intake within dietary ranges typically observed in most modern societies. A subnormal ability to vasodilate in

  20. About the wind energetics development

    International Nuclear Information System (INIS)

    Strebkov, D.S.; Kharitonov, V.P.; Murugov, V.P.; Sokol'skij, A.K.

    1996-01-01

    The review of wind power energetics state in USA, Europe, Russia is given. The data of EC on wind power plants production in different periods are presented. The directions of scientific-research works with the purpose of increasing the level of wind power industry of Russia corresponding to economics demands were elaborated. (author). 8 refs., 3 tabs

  1. Numerical Analysis of the Effect of Active Wind Speed and Direction on Circulation of Sea of Azov Water with and without Allowance for the Water Exchange through the Kerch Strait

    Science.gov (United States)

    Cherkesov, L. V.; Shul'ga, T. Ya.

    2018-01-01

    The effect of seawater movement through the Kerch Strait for extreme deviations in the level and speed of currents in the Sea of Azov caused by the action of climate wind fields has been studied using the Princeton ocean model (POM), a general three-dimensional nonlinear model of ocean circulation. Formation of the water flow through the strait is caused by the long-term action of the same type of atmospheric processes. The features of the water dynamics under conditions of changing intensity and active wind direction have been studied. Numerical experiments were carried out for two versions of model Sea of Azov basins: closed (without the Kerch Strait) and with a fluid boundary located in the Black Sea. The simulation results have shown that allowance for the strait leads to a significant change in the velocities of steady currents and level deviations at wind speeds greater than 5 m/s. The most significant effect on the parameters of steady-state movements is exerted by the speed of the wind that generates them; allowance for water exchange through the strait is less important. Analysis of the directions of atmospheric circulation has revealed that the response generated by the movement of water through the strait is most pronounced when a southeast wind is acting.

  2. Simulating coastal effects on an offshore wind farm

    DEFF Research Database (Denmark)

    van der Laan, Paul; Pena Diaz, Alfredo; Volker, Patrick

    Wind turbine wakes can cause energy losses in wind farms1 and their effect needs to be modeled in order to design energy efficient wind farm layouts. Wake losses in offshore wind farms are often modeled by assuming offshore conditions for all wind directions; however, many offshore wind farms...

  3. Modeling of wind turbines for power system studies

    Energy Technology Data Exchange (ETDEWEB)

    Petru, T.

    2001-05-01

    When wind turbines are installed into the electric grid, the power quality is affected. Today, strict installation recommendations often prevail due to a lack of knowledge on this subject. Consequently, it is important to predict the impact of wind turbines on the electric grid before the turbines are installed. The thesis describes relevant power quality issues, discusses different configurations of wind turbines with respect to power quality and draw requirements regarding wind turbine modeling. A model of a stall-regulated, fixed-speed wind turbine system is introduced and its power quality impact on the electric grid is evaluated. The model is verified with field measurements.

  4. Shorlist Masterplan Wind. Evaluation of the sampling grid of the year-round ichthyoplankton survey

    NARCIS (Netherlands)

    Bolle, L.J.; Beek, van J.K.L.

    2011-01-01

    Within the research programme 'Shortlist Masterplan Wind' a year-round ichthyoplankton survey is being carried out. The sampling area is based on known spawning concentrations and prevailing currents.

  5. Potential health impact of wind turbines

    International Nuclear Information System (INIS)

    2010-05-01

    In response to public health concerns about wind turbines, a study was conducted to review the scientific evidence on the potential health effects of wind turbines. Several research questions were examined, including scientific evidence on the potential health impacts of wind turbines; the relationship between wind turbine noise and health; the relationship between low frequency sound, infrasound and health; assessment of exposure to wind turbines; wind turbine health and safety hazards and Ontario wind turbine setbacks; community consultation prior to wind farm construction and data gaps and research needs. The study showed that although some people living near wind turbines reported symptoms such as dizziness, headaches, and sleep disturbance, the scientific evidence available to date does not demonstrate a direct causal link between wind turbine noise and adverse health effects. The sound level from wind turbines at common residential setbacks is not sufficient to cause hearing impairment or other direct health effects, although some people may find it annoying. 41 refs., 1 appendix.

  6. Potential health impact of wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2010-05-15

    In response to public health concerns about wind turbines, a study was conducted to review the scientific evidence on the potential health effects of wind turbines. Several research questions were examined, including scientific evidence on the potential health impacts of wind turbines; the relationship between wind turbine noise and health; the relationship between low frequency sound, infrasound and health; assessment of exposure to wind turbines; wind turbine health and safety hazards and Ontario wind turbine setbacks; community consultation prior to wind farm construction and data gaps and research needs. The study showed that although some people living near wind turbines reported symptoms such as dizziness, headaches, and sleep disturbance, the scientific evidence available to date does not demonstrate a direct causal link between wind turbine noise and adverse health effects. The sound level from wind turbines at common residential setbacks is not sufficient to cause hearing impairment or other direct health effects, although some people may find it annoying. 41 refs., 1 appendix.

  7. Wind Structure and Wind Loading

    DEFF Research Database (Denmark)

    Brorsen, Michael

    The purpose of this note is to provide a short description of wind, i.e. of the flow in the atmosphere of the Earth and the loading caused by wind on structures. The description comprises: causes to the generation of windhe interaction between wind and the surface of the Earthhe stochastic nature...... of windhe interaction between wind and structures, where it is shown that wind loading depends strongly on this interaction...

  8. Empirical investigation of wind farm blockage effects in Horn Rev 1 offshore wind farm

    DEFF Research Database (Denmark)

    Mitraszewski, Karol; Hansen, Kurt Schaldemose; Nygaard, Nicolai

    We present an empirical study of wind farm blockage effects based on Horns Rev 1 SCADA data. The mean inflow non-uniformities in wind speed are analyzed by calculating the mean power outputs of turbines located along the outer edges of the farm for different wind directions, wind speeds and stabi......We present an empirical study of wind farm blockage effects based on Horns Rev 1 SCADA data. The mean inflow non-uniformities in wind speed are analyzed by calculating the mean power outputs of turbines located along the outer edges of the farm for different wind directions, wind speeds...

  9. Prevailing theories of consciousness are challenged by novel cross-modal associations acquired between subliminal stimuli.

    Science.gov (United States)

    Scott, Ryan B; Samaha, Jason; Chrisley, Ron; Dienes, Zoltan

    2018-06-01

    While theories of consciousness differ substantially, the 'conscious access hypothesis', which aligns consciousness with the global accessibility of information across cortical regions, is present in many of the prevailing frameworks. This account holds that consciousness is necessary to integrate information arising from independent functions such as the specialist processing required by different senses. We directly tested this account by evaluating the potential for associative learning between novel pairs of subliminal stimuli presented in different sensory modalities. First, pairs of subliminal stimuli were presented and then their association assessed by examining the ability of the first stimulus to prime classification of the second. In Experiments 1-4 the stimuli were word-pairs consisting of a male name preceding either a creative or uncreative profession. Participants were subliminally exposed to two name-profession pairs where one name was paired with a creative profession and the other an uncreative profession. A supraliminal task followed requiring the timed classification of one of those two professions. The target profession was preceded by either the name with which it had been subliminally paired (concordant) or the alternate name (discordant). Experiment 1 presented stimuli auditorily, Experiment 2 visually, and Experiment 3 presented names auditorily and professions visually. All three experiments revealed the same inverse priming effect with concordant test pairs associated with significantly slower classification judgements. Experiment 4 sought to establish if learning would be more efficient with supraliminal stimuli and found evidence that a different strategy is adopted when stimuli are consciously perceived. Finally, Experiment 5 replicated the unconscious cross-modal association achieved in Experiment 3 utilising non-linguistic stimuli. The results demonstrate the acquisition of novel cross-modal associations between stimuli which are not

  10. Prevailing trends of climatic extremes across Indus-Delta of Sindh-Pakistan

    Science.gov (United States)

    Abbas, Farhat; Rehman, Iqra; Adrees, Muhammad; Ibrahim, Muhammad; Saleem, Farhan; Ali, Shafaqat; Rizwan, Muhammad; Salik, Muhammad Raza

    2018-02-01

    This study examines the variability and change in the patterns of climatic extremes experienced in Indus-Delta of Sindh province of Pakistan, comprising regions of Karachi, Badin, Mohenjodaro, and Rohri. The homogenized daily minimum and maximum temperature and precipitation data for a 36-year period were used to calculate 13 and 11 indices of temperature and precipitation extremes with the help of RClimDex, a program written in the statistical software package R. A non-parametric Mann-Kendall test and Sen's slope estimates were used to determine the statistical significance and magnitude of the calculated trend. Temperatures of summer days and tropical nights increased in the region with overall significant warming trends for monthly maximum temperature as well as for warm days and nights reflecting dry conditions in the study area. The warm extremes and nighttime temperature indices showed greater trends than cold extremes and daytime indices depicting an overall warming trends in the Delta. Historic decrease in the acreage of major crops and over 33% decrease in agriculture credit for Sindh are the indicators of adverse impacts of warmer and drier weather on Sindh agriculture. Trends reported for Karachi and Badin are expected to decrease rice cultivation, hatching of fisheries, and mangroves forest surrounding these cities. Increase in the prevailing temperature trends will lead to increasingly hotter and drier summers resulting to constraints on cotton, wheat, and rice yield in Rohri and Mohenjodaro areas due to increased crop water requirements that may be met with additional groundwater pumping; nonetheless, the depleted groundwater resources would have a direct impact on the region's economy.

  11. Current direction, chemical, benthic organisms, and wind wave spectra data from moored current meter casts and other instruments in the Gulf of Mexico as part of the Brine Disposal project, 1977-10-14 to 1979-08-24 (NODC Accession 7900335)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, chemical, benthic organisms, and wind direction data were collected using moored current meter casts and other instruments in the Gulf of Mexico...

  12. Optimal siting and sizing of wind farms

    NARCIS (Netherlands)

    Cetinay-Iyicil, H.; Kuipers, F.A.; Guven, A. Nezih

    2017-01-01

    In this paper, we propose a novel technique to determine the optimal placement of wind farms, thereby taking into account wind characteristics and electrical grid constraints. We model the long-term variability of wind speed using a Weibull distribution according to wind direction intervals, and

  13. Urban Wind Energy

    DEFF Research Database (Denmark)

    Beller, Christina

    for the installation of wind turbines in cities, with Copenhagen, DK, as example. Focus is taken on turbine with a swept area of maximum 5m2, since turbines of this size are relatively easy to be integrated in the urban space and are in the financial range for small companies as well as for private persons. Elements......New trends e.g. in architecture and urban planning are to reduce energy needs. Several technologies are employed to achieve this, and one of the technologies, not new as such, is wind energy. Wind turbines are installed in cities, both by companies and private persons on both old and new buildings...... the lower wind energy in cities other factors foster the attractiveness of urban wind energy application, like the demand or wish to reduce CO2 emissions and the possibility to produce energy directly to ones household....

  14. Illinois Wind Workers Group

    Energy Technology Data Exchange (ETDEWEB)

    David G. Loomis

    2012-05-28

    The Illinois Wind Working Group (IWWG) was founded in 2006 with about 15 members. It has grown to over 200 members today representing all aspects of the wind industry across the State of Illinois. In 2008, the IWWG developed a strategic plan to give direction to the group and its activities. The strategic plan identifies ways to address critical market barriers to the further penetration of wind. The key to addressing these market barriers is public education and outreach. Since Illinois has a restructured electricity market, utilities no longer have a strong control over the addition of new capacity within the state. Instead, market acceptance depends on willing landowners to lease land and willing county officials to site wind farms. Many times these groups are uninformed about the benefits of wind energy and unfamiliar with the process. Therefore, many of the project objectives focus on conferences, forum, databases and research that will allow these stakeholders to make well-educated decisions.

  15. Direct Optical Ice Sensing and Closed-Loop Controller Design for Active De-icing of Wind Turbines Using Distributed Heating

    Science.gov (United States)

    Shajiee, Shervin

    Ice accumulation on wind turbines operating in cold regions reduces power generation by degrading aerodynamic efficiency and causes mass imbalance and fatigue loads on the blades. Due to blade rotation and variation of the pitch angle, different locations on the blade experience large variations of Reynolds number, Nusselt number, heat loss, and non-uniform ice distribution. Hence, applying different amounts of heat flux in different blade locations can provide more effective de-icing for the same total power consumption. This large variation of required heat flux motivates using distributed resistive heating, with the capability of locally adjusting thermal power as a function of location on the blade. The main contributions of this research are developing the experimental feasibility of direct ice sensing using an optical sensing technique as well as development of a computational framework for implementation of closed-loop localized active de-icing using distributed sensing. A script-base module was developed in a commercial finite-element software (ANSYS) which provides the capability of (i) Closed-loop de-icing simulations for a distributed network of sensors and actuators, (ii) investigating different closed-loop thermal control schemes and their de-icing efficiency (iii) optimizing thermal actuation for a distributed resistive heating, and (iv) analyzing different faulty scenarios for sensors and thermal actuators under known faults in the network. Different surrogate models were used to enhance the computational efficiency of this approach. The results showed that optimal value of control parameters in a distributed network of heaters depends on convective heat transfer characteristics, layout of heaters and type of closed-loop controller scheme used for thermal actuation. Furthermore, It was shown that closed-loop control provides much faster de-icing than the open-loop constant heat flux thermal actuation. It was observed both experimentally and

  16. Full-Scale Fatigue Testing of a Wind Turbine Blade in Flapwise Direction and Examining the Effect of Crack Propagation on the Blade Performance

    Directory of Open Access Journals (Sweden)

    Othman Al-Khudairi

    2017-10-01

    Full Text Available In this paper, the sensitivity of the structural integrity of wind turbine blades to debonding of the shear web from the spar cap was investigated. In this regard, modal analysis, static and fatigue testing were performed on a 45.7 m blade for three states of the blade: (i as received blade (ii when a crack of 200 mm was introduced between the web and the spar cap and (iii when the crack was extended to 1000 mm. Calibration pull-tests for all three states of the blade were performed to obtain the strain-bending moment relationship of the blade according to the estimated target bending moment (BM which the blade is expected to experience in its service life. The resultant data was used to apply appropriate load in the fatigue tests. The blade natural frequencies in flapwise and edgewise directions over a range of frequency domain were found by modal testing for all three states of the blade. The blade first natural frequency for each state was used for the flapwise fatigue tests. These were performed in accordance with technical specification IEC TS 61400-23. The fatigue results showed that, for a 200 mm crack between the web and spar cap at 9 m from the blade root, the crack did not propagate at 50% of the target BM up to 62,110 cycles. However, when the load was increased to 70% of target BM, some damages were detected on the pressure side of the blade. When the 200 mm crack was extended to 1000 mm, the crack began to propagate when the applied load exceeded 100% of target BM and the blade experienced delaminations, adhesive joint failure, compression failure and sandwich core failure.

  17. Full-Scale Fatigue Testing of a Wind Turbine Blade in Flapwise Direction and Examining the Effect of Crack Propagation on the Blade Performance.

    Science.gov (United States)

    Al-Khudairi, Othman; Hadavinia, Homayoun; Little, Christian; Gillmore, Gavin; Greaves, Peter; Dyer, Kirsten

    2017-10-03

    In this paper, the sensitivity of the structural integrity of wind turbine blades to debonding of the shear web from the spar cap was investigated. In this regard, modal analysis, static and fatigue testing were performed on a 45.7 m blade for three states of the blade: (i) as received blade (ii) when a crack of 200 mm was introduced between the web and the spar cap and (iii) when the crack was extended to 1000 mm. Calibration pull-tests for all three states of the blade were performed to obtain the strain-bending moment relationship of the blade according to the estimated target bending moment (BM) which the blade is expected to experience in its service life. The resultant data was used to apply appropriate load in the fatigue tests. The blade natural frequencies in flapwise and edgewise directions over a range of frequency domain were found by modal testing for all three states of the blade. The blade first natural frequency for each state was used for the flapwise fatigue tests. These were performed in accordance with technical specification IEC TS 61400-23. The fatigue results showed that, for a 200 mm crack between the web and spar cap at 9 m from the blade root, the crack did not propagate at 50% of the target BM up to 62,110 cycles. However, when the load was increased to 70% of target BM, some damages were detected on the pressure side of the blade. When the 200 mm crack was extended to 1000 mm, the crack began to propagate when the applied load exceeded 100% of target BM and the blade experienced delaminations, adhesive joint failure, compression failure and sandwich core failure.

  18. MCMC for Wind Power Simulation

    NARCIS (Netherlands)

    Papaefthymiou, G.; Klöckl, B.

    2008-01-01

    This paper contributes a Markov chain Monte Carlo (MCMC) method for the direct generation of synthetic time series of wind power output. It is shown that obtaining a stochastic model directly in the wind power domain leads to reduced number of states and to lower order of the Markov chain at equal

  19. Wind Characteristics and Wind Energy Potential in the Golf of Tunis

    International Nuclear Information System (INIS)

    Dahmouni, A.W.; Ben Salah, M.; Kerkeni, C.; Askri, F.; Ben Nasrallah, S.

    2009-01-01

    This paper presents a study of wind resource in the Golf of Tunis. Experimental measurement of wind speed and wind direction, are conducted. The statistic treatment of results permitted us to evaluate the most characteristics of wind energy in the studied site. The obtained results can be used to perform wind power designs and confirm that the Golf of Tunis has promising wind energy potential

  20. Wind Power in Georgia

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2012-11-01

    Georgia has good wind power potential. Preliminary analyses show that the technical wind power potential in Georgia is good. Meteorological data shows that Georgia has four main areas in Georgia with annual average wind speeds of over 6 m/s and two main areas with 5-6 m/s at 80m. The most promising areas are the high mountain zone of the Great Caucasus, The Kura river valley, The South-Georgian highland and the Southern part of the Georgian Black Sea coast. Czech company Wind Energy Invest has recently signed a Memorandum of Understanding with Georgian authorities for development of the first wind farm in Georgia, a 50MW wind park in Paravani, Southern Georgia, to be completed in 2014. Annual generation is estimated to 170.00 GWh and the investment estimated to 101 million US$. Wind power is suited to balance hydropower in the Georgian electricity sector Electricity generation in Georgia is dominated by hydro power, constituting 88% of total generation in 2009. Limited storage capacity and significant spring and summer peaks in river flows result in an uneven annual generation profile and winter time shortages that are covered by three gas power plants. Wind power is a carbon-free energy source well suited to balance hydropower, as it is available (often strongest) in the winter and can be exported when there is a surplus. Another advantage with wind power is the lead time for the projects; the time from site selection to operation for a wind power park (approximately 2.5 years) is much shorter than for hydro power (often 6-8 years). There is no support system or scheme for renewable sources in Georgia, so wind power has to compete directly with other energy sources and is in most cases more expensive to build than hydro power. In a country and region with rapidly increasing energy demands, the factors described above nevertheless indicate that there is a commercial niche and a role to play for Georgian wind power. Skra: An example of a wind power development

  1. 78 FR 60181 - Prevailing Rate Systems; Redefinition of the Clayton-Cobb-Fulton, Georgia, Nonappropriated Fund...

    Science.gov (United States)

    2013-10-01

    ... OFFICE OF PERSONNEL MANAGEMENT 5 CFR Part 532 RIN 3206-AM84 Prevailing Rate Systems; Redefinition.... Office of Personnel Management. ACTION: Final rule. SUMMARY: The U.S. Office of Personnel Management (OPM..., from the wage area definition. The name of the wage area will be Cobb, GA. These changes are necessary...

  2. 20 CFR 656.40 - Determination of prevailing wage for labor certification purposes.

    Science.gov (United States)

    2010-04-01

    ... association of six or more professional sports teams whose total combined revenues exceed $10,000,000 per year... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false Determination of prevailing wage for labor certification purposes. 656.40 Section 656.40 Employees' Benefits EMPLOYMENT AND TRAINING ADMINISTRATION...

  3. 78 FR 60182 - Prevailing Rate Systems; Definition of Broward County, Florida, to a Nonappropriated Fund Federal...

    Science.gov (United States)

    2013-10-01

    ... OFFICE OF PERSONNEL MANAGEMENT 5 CFR Part 532 RIN 3206-AM83 Prevailing Rate Systems; Definition of... Personnel Management. ACTION: Final rule. SUMMARY: The U.S. Office of Personnel Management (OPM) is issuing a final rule to define Broward County, FL, as an area of application county to the Miami-Dade, FL...

  4. 78 FR 29658 - Prevailing Rate Systems; Definition of Broward County, Florida, to a Nonappropriated Fund Federal...

    Science.gov (United States)

    2013-05-21

    ... Management is issuing a proposed rule that would define Broward County, Florida, as an area of application... Management (OPM) is issuing a proposed rule that would define Broward County, Florida, as an area of... OFFICE OF PERSONNEL MANAGEMENT 5 CFR Part 532 RIN 3206-AM83 Prevailing Rate Systems; Definition of...

  5. 76 FR 9640 - Prevailing Rate Systems: Santa Clara, CA, Tulsa County, OK, and Angelina County, TX

    Science.gov (United States)

    2011-02-22

    ...: Final rule. SUMMARY: The U.S. Office of Personnel Management is issuing a final rule to define Tulsa... Management (OPM) issued a proposed rule (75 FR 45557) to define Tulsa County, Oklahoma, as an area of... OFFICE OF PERSONNEL MANAGEMENT 5 CFR Part 532 RIN 3206-AM22 Prevailing Rate Systems: Santa Clara...

  6. The Wind Energy Potential of Kurdistan, Iran

    OpenAIRE

    Arefi, Farzad; Moshtagh, Jamal; Moradi, Mohammad

    2014-01-01

    In the current work by using statistical methods and available software, the wind energy assessment of prone regions for installation of wind turbines in, Qorveh, has been investigated. Information was obtained from weather stations of Baneh, Bijar, Zarina, Saqez, Sanandaj, Qorveh, and Marivan. The monthly average and maximum of wind speed were investigated between the years 2000?2010 and the related curves were drawn. The Golobad curve (direction and percentage of dominant wind and calm wind...

  7. Wind power

    International Nuclear Information System (INIS)

    Gipe, P.

    2007-01-01

    This book is a translation of the edition published in the USA under the title of ''wind power: renewable energy for home, farm and business''. In the wake of mass blackouts and energy crises, wind power remains a largely untapped resource of renewable energy. It is a booming worldwide industry whose technology, under the collective wing of aficionados like author Paul Gipe, is coming of age. Wind Power guides us through the emergent, sometimes daunting discourse on wind technology, giving frank explanations of how to use wind technology wisely and sound advice on how to avoid common mistakes. Since the mid-1970's, Paul Gipe has played a part in nearly every aspect of wind energy development from installing small turbines to promoting wind energy worldwide. As an American proponent of renewable energy, Gipe has earned the acclaim and respect of European energy specialists for years, but his arguments have often fallen on deaf ears at home. Today, the topic of wind power is cropping up everywhere from the beaches of Cape Cod to the Oregon-Washington border, and one wind turbine is capable of producing enough electricity per year to run 200 average American households. Now, Paul Gipe is back to shed light on this increasingly important energy source with a revised edition of Wind Power. Over the course of his career, Paul Gipe has been a proponent, participant, observer, and critic of the wind industry. His experience with wind has given rise to two previous books on the subject, Wind Energy Basics and Wind Power for Home and Business, which have sold over 50,000 copies. Wind Power for Home and Business has become a staple for both homeowners and professionals interested in the subject, and now, with energy prices soaring, interest in wind power is hitting an all-time high. With chapters on output and economics, Wind Power discloses how much you can expect from each method of wind technology, both in terms of energy and financial savings. The book updated models

  8. Wind Speed Perception and Risk

    Science.gov (United States)

    Agdas, Duzgun; Webster, Gregory D.; Masters, Forrest J.

    2012-01-01

    Background How accurately do people perceive extreme wind speeds and how does that perception affect the perceived risk? Prior research on human–wind interaction has focused on comfort levels in urban settings or knock-down thresholds. No systematic experimental research has attempted to assess people's ability to estimate extreme wind speeds and perceptions of their associated risks. Method We exposed 76 people to 10, 20, 30, 40, 50, and 60 mph (4.5, 8.9, 13.4, 17.9, 22.3, and 26.8 m/s) winds in randomized orders and asked them to estimate wind speed and the corresponding risk they felt. Results Multilevel modeling showed that people were accurate at lower wind speeds but overestimated wind speeds at higher levels. Wind speed perceptions mediated the direct relationship between actual wind speeds and perceptions of risk (i.e., the greater the perceived wind speed, the greater the perceived risk). The number of tropical cyclones people had experienced moderated the strength of the actual–perceived wind speed relationship; consequently, mediation was stronger for people who had experienced fewer storms. Conclusion These findings provide a clearer understanding of wind and risk perception, which can aid development of public policy solutions toward communicating the severity and risks associated with natural disasters. PMID:23226230

  9. Wind speed perception and risk.

    Directory of Open Access Journals (Sweden)

    Duzgun Agdas

    Full Text Available BACKGROUND: How accurately do people perceive extreme wind speeds and how does that perception affect the perceived risk? Prior research on human-wind interaction has focused on comfort levels in urban settings or knock-down thresholds. No systematic experimental research has attempted to assess people's ability to estimate extreme wind speeds and perceptions of their associated risks. METHOD: We exposed 76 people to 10, 20, 30, 40, 50, and 60 mph (4.5, 8.9, 13.4, 17.9, 22.3, and 26.8 m/s winds in randomized orders and asked them to estimate wind speed and the corresponding risk they felt. RESULTS: Multilevel modeling showed that people were accurate at lower wind speeds but overestimated wind speeds at higher levels. Wind speed perceptions mediated the direct relationship between actual wind speeds and perceptions of risk (i.e., the greater the perceived wind speed, the greater the perceived risk. The number of tropical cyclones people had experienced moderated the strength of the actual-perceived wind speed relationship; consequently, mediation was stronger for people who had experienced fewer storms. CONCLUSION: These findings provide a clearer understanding of wind and risk perception, which can aid development of public policy solutions toward communicating the severity and risks associated with natural disasters.

  10. Wind turbine rotor aerodynamics : The IEA MEXICO rotor explained

    NARCIS (Netherlands)

    Zhang, Y.

    2017-01-01

    Wind turbines are operating under very complex and uncontrolled environmental conditions, including atmospheric turbulence, atmospheric boundary layer effects, directional and spatial variations in wind shear, etc. Over the past decades, the size of a commercial wind turbine has increased

  11. RSS MONTHLY 1-DEG MERGED WIND CLIMATOLOGY NETCDF V7

    Data.gov (United States)

    National Aeronautics and Space Administration — The RSS Monthly 1-deg Merged Wind Climatology netCDF dataset provides one degree gridded data for the monthly means of wind speed and wind direction, a 20 year...

  12. Time Series Model of Wind Speed for Multi Wind Turbines based on Mixed Copula

    Directory of Open Access Journals (Sweden)

    Nie Dan

    2016-01-01

    Full Text Available Because wind power is intermittent, random and so on, large scale grid will directly affect the safe and stable operation of power grid. In order to make a quantitative study on the characteristics of the wind speed of wind turbine, the wind speed time series model of the multi wind turbine generator is constructed by using the mixed Copula-ARMA function in this paper, and a numerical example is also given. The research results show that the model can effectively predict the wind speed, ensure the efficient operation of the wind turbine, and provide theoretical basis for the stability of wind power grid connected operation.

  13. Wind Turbines Adaptation to the Variability of the Wind Field

    Science.gov (United States)

    Ulianov, Yuriy; Martynenko, Gennadii; Misaylov, Vitaliy; Soliannikova, Iuliia

    2010-05-01

    WIND TURBINES ADAPTATION TO THE VARIABILITY OF THE WIND FIELD The subject of our scientific research is wind power turbines (WPT) with the horizontal axis which were now common in the world. Efficient wind turbines work is largely determined by non-stationarity of the wind field, expressed in its gustiness, the presence of vertical and horizontal shifts of wind speed and direction. At critical values of the wind parameters WPT has aerodynamic and mechanical overload, leading to breakdowns, premature wear and reduce the life of the wind turbine. To prevent accidents at the peak values of wind speed it is used the regulatory system of windwheels. WPT control systems provide a process orientation of the wind turbine rotor axis in the line of the mean wind. Wind turbines are also equipped with braking device used to protect against breakdowns when a significant increase in the wind. In general, all these methods of regulation are not always effective. Thus, in practice there may be situations when the wind speed is many times greater than the stated limit. For example, if there are microbursts in the atmospheric boundary layer, low-level wind shears caused by its gust front, storms, etc. It is required for a wind power turbine adaptation to intensive short-term wind impulses and considerable vertical wind shifts that the data about them shall be obtained ahead of time. To do this it is necessary to have the information on the real structure of the wind field in the area of the blade sweep for the minimum range against the wind that is determined by the mean speed and the system action time. The implementation of acoustic and laser traditional wind sounding systems is limited by ambient acoustic noise, by heavy rain, snowfall and by fog. There are free of these disadvantages the inclined radioacoustic sounding (IRASS) technique which works for a system of remote detection and control of wind gusts. IRASS technique is realized as low-potential Doppler pulse radar

  14. Combining radar and direct observation to estimate pelican collision risk at a proposed wind farm on the Cape west coast, South Africa

    Science.gov (United States)

    Reid, Tim; du Plessis, Johan; Colyn, Robin; Benn, Grant; Millikin, Rhonda

    2018-01-01

    Pre-construction assessments of bird collision risk at proposed wind farms are often confounded by insufficient or poor quality data describing avian flight paths through the development area. These limitations can compromise the practical value of wind farm impact studies. We used radar- and observer-based methods to quantify great white pelican flights in the vicinity of a planned wind farm on the Cape west coast, South Africa, and modelled turbine collision risk under various scenarios. Model outputs were combined with pre-existing demographic data to evaluate the possible influence of the wind farm on the pelican population, and to examine impact mitigation options. We recorded high volumes of great white pelican movement through the wind farm area, coincident with the breeding cycle of the nearby colony and associated with flights to feeding areas located about 50 km away. Pelicans were exposed to collision risk at a mean rate of 2.02 High Risk flights.h-1. Risk was confined to daylight hours, highest during the middle of the day and in conditions of strong north-westerly winds, and 82% of High Risk flights were focused on only five of the proposed 35 turbine placements. Predicted mean mortality rates (22 fatalities.yr-1, 95% Cl, 16–29, with average bird and blade speeds and 95% avoidance rates) were not sustainable, resulting in a negative population growth rate (λ = 0.991). Models suggested that removal of the five highest risk turbines from the project, or institution of a curtailment regimen that shuts down at least these turbines at peak traffic times, could theoretically reduce impacts to manageable levels. However, in spite of the large quantities of high quality data used in our analyses, our collision risk model remains compromised by untested assumptions about pelican avoidance rates and uncertainties about the existing dynamics of the pelican population, and our findings are probably not reliable enough to ensure sustainable development. PMID

  15. Influence of the wind direction on the chloride profiles of structures close to the Caribbean Sea. The case of the Turiguanó- Coco Key Viaduct in Cuba

    Directory of Open Access Journals (Sweden)

    Pérez García, E. J.

    2005-03-01

    Full Text Available Interpretation of chlorides profiles is important to predict concrete structures service life, among other factors. However, reported results are, in general, from small specimens exposed to specific atmospheres instead of real structures. The objective of this work was the obtention and interpretation of the chlorides profiles forms from several bridges of the Turiguanó-Coco Key viaduct in Cuba. The results verified data from other authors but on different structural elements and similar atmospheres. The form of the chloride profile for structures similar to those in the viaduct bridges, exposed to tropical marine atmosphere, is consistent and changes in intensity with the winds direction and the blocking to them by parts of the structure. The possible effect of the wet and drying process is also discussed.

    En años recientes se le ha dado importancia a la interpretación de los perfiles de cloruros en el hormigón armado con fines de predicción de vida útil, entre otros. Sin embargo, los datos que se han constatado pertenecen, por lo general, a experimentos sobre probetas que han sido expuestas, por un tiempo determinado, a atmósferas específicas más que a estructuras reales. El objetivo de este trabajo fue la obtención e interpretación de la forma de los perfiles de cloruros de varios puentes del viaducto Turiguanó-Cayo Coco en Cuba. Los resultados ratificaron los datos encontrados por otros autores en otros elementos y ambientes similares, pero en un tipo de estructura diferente. En todos los casos estudiados se pudo verificar que, la forma del perfil de concentración de cloruros para estructuras similares a los puentes del viaducto estudiado expuestas a un ambiente tropical marino, es consistente y cambia de intensidad con la dirección de los vientos y del apantallamiento a los mismos por parte de la estructura y de sus partes. Se discute el posible efecto del mojado y secado.

  16. Semiconductor Laser Lidar Wind Velocity Sensor for Turbine Control

    DEFF Research Database (Denmark)

    Rodrigo, Peter John; Hu, Qi; Pedersen, Christian

    2014-01-01

    A dual line-of-sight CW lidar that measures both wind speed and direction is presented . The wind lidar employs a semiconductor laser, which allows for inexpensive remote sensors geared towards enhanced control of wind turbines .......A dual line-of-sight CW lidar that measures both wind speed and direction is presented . The wind lidar employs a semiconductor laser, which allows for inexpensive remote sensors geared towards enhanced control of wind turbines ....

  17. Wind power forecast error smoothing within a wind farm

    International Nuclear Information System (INIS)

    Saleck, Nadja; Bremen, Lueder von

    2007-01-01

    Smoothing of wind power forecast errors is well-known for large areas. Comparable effects within a wind farm are investigated in this paper. A Neural Network was taken to predict the power output of a wind farm in north-western Germany comprising 17 turbines. A comparison was done between an algorithm that fits mean wind and mean power data of the wind farm and a second algorithm that fits wind and power data individually for each turbine. The evaluation of root mean square errors (RMSE) shows that relative small smoothing effects occur. However, it can be shown for this wind farm that individual calculations have the advantage that only a few turbines are needed to give better results than the use of mean data. Furthermore different results occurred if predicted wind speeds are directly fitted to observed wind power or if predicted wind speeds are first fitted to observed wind speeds and then applied to a power curve. The first approach gives slightly better RMSE values, the bias improves considerably

  18. Wind farm production estimates

    DEFF Research Database (Denmark)

    Larsen, Torben J.; Larsen, Gunner Chr.; Aagaard Madsen, Helge

    2012-01-01

    inves- tigated for a full polar (i.e. as function of mean inflow wind direction). This investigation relates to a mean wind speed bin defined as 8m=s±1m=s. The impact of ambient turbu- lence intensity and turbine inter spacing on the production of a wind turbine operating under full wake conditions...... is investi- gated. Four different turbine inter spacings, ranging between 3.8 and 10.4 rotor diameters, are analyzed for ambient turbu- lence intensities varying between 2% and 20%. This analysis is based on full scale production data from three other wind farms Wieringermeer [3], Horns Rev [4] and Nysted [5......]. A very satisfactory agreement between experimental data and predictions is observed. This paper finally includes additionally an analysis of the production impact caused by atmospheric stability effects. For this study, atmospheric stability conditions are defined in terms of the Monin-Obukhov length...

  19. 75 FR 11935 - Technical Change to the Filing Location of Prevailing Wage Determinations for Use in the H-1B, H...

    Science.gov (United States)

    2010-03-12

    ... (Australia), and Permanent Labor Certification Programs; Prevailing Wage Determinations for Use in the... (Australia), and Permanent Labor Certification Programs; Prevailing Wage Determinations for Use in the...

  20. CFD analysis of a Darrieus wind turbine

    Science.gov (United States)

    Niculescu, M. L.; Cojocaru, M. G.; Pricop, M. V.; Pepelea, D.; Dumitrache, A.; Crunteanu, D. E.

    2017-07-01

    The Darrieus wind turbine has some advantages over the horizontal-axis wind turbine. Firstly, its tip speed ratio is lower than that of the horizontal-axis wind turbine and, therefore, its noise is smaller, privileging their placement near populated areas. Secondly, the Darrieus wind turbine does needs no orientation mechanism with respect to wind direction in contrast to the horizontal-axis wind turbine. However, the efficiency of the Darrieus wind turbine is lower than that of the horizontal-axis wind turbine since its aerodynamics is much more complex. With the advances in computational fluids and computers, it is possible to simulate the Darrieus wind turbine more accurately to understand better its aerodynamics. For these reasons, the present papers deals with the computational aerodynamics of a Darrieus wind turbine applying the state of the art of CFD methods (anisotropic turbulence models, transition from laminar to turbulent, scale adaptive simulation) to better understand its unsteady behavior.

  1. Benthic diversity of River Gomti in relation to the prevailing environmental conditions in Lucknow

    OpenAIRE

    Varshney, P.K.; Agrahari, R.K.; Singh, S.K.; Jain, A.K.

    2006-01-01

    To evaluate the benthic diversity of River Gomti in relation to the prevailing environmental conditions, four stations, viz., Maa Chandrika Devi, Daliganj, Ambedkar Park and Aquaduct, were identified from upstream to downstream along the course of the river in Lucknow. Dissolved oxygen was low on many occasions at all the stations except Maa Chandrika Devi and chemical oxygen demand values were high. There was a gradual increase in mean nitrite and phosphate values from up to downstream. Bent...

  2. Why nature prevails over nurture in the making of the elite athlete

    OpenAIRE

    Georgiades, Evelina; Klissouras, Vassilis; Baulch, Jamie; Wang, Guan; Pitsiladis, Yannis

    2017-01-01

    While the influence of nature (genes) and nurture (environment) on elite sporting performance remains difficult to precisely determine, the dismissal of either as a contributing factor to performance is unwarranted. It is accepted that a complex interaction of a combination of innumerable factors may mold a talented athlete into a champion. The prevailing view today is that understanding elite human performance will require the deciphering of two major sources of individual differences, genes...

  3. Wind height distribution influence on offshore wind farm feasibility study

    Science.gov (United States)

    Benassai, Guido; Della Morte, Renata; Matarazzo, Antonio; Cozzolino, Luca

    2015-04-01

    The economic feasibility of offshore wind power utilization depends on the favourable wind conditions offshore as compared to sites on land. The higher wind speeds have to compensate the additional cost of offshore developments. However, not only the mean wind speed is different, but the whole flow regime, as can be seen in the vertical wind speed profile. The commonly used models to describe this profile have been developed mainly for land sites, so they have to be verified on the basis of field data. Monin-Obukhov theory is often used for the description of the wind speed profile at a different height with respect to a measurement height. Starting from the former, , the profile is predicted using two parameters, Obukhov length and sea surface roughness. For situations with near-neutral and stable atmospheric stratification and long (>30km) fetch, the wind speed increase with height is larger than what is predicted from Monin-Obukhov theory. It is also found that this deviation occurs at wind speeds important for wind power utilization, mainly at 5-9 ms-1. In the present study the influence of these aspects on the potential site productivity of an offshore wind farm were investigated, namely the deviation from the theory of Monin-Obukhov due to atmospheric stability and the influence of the fetch length on the Charnock model. Both these physical effects were discussed and examined in view of a feasibility study of a site for offshore wind farm in Southern Italy. Available data consisted of time histories of wind speeds and directions collected by National Tidegauge Network (Rete Mareografica Nazionale) at the height of 10m a.s.l. in ports. The theory of Monin-Obukhov was used to extrapolate the data to the height of the wind blades, while the Charnock model was used to extend the wind speed on the sea surface from the friction velocity on the ground. The models described were used to perform calculations for a feasibility study of an offshore wind farm in Southern

  4. Wind Load Assessment of a Large Radar Antenna using Measurements and Simulation

    Science.gov (United States)

    Weerasinghe, Rohitha; Bunn, Thomas

    2017-11-01

    Radar structures are subject to heavy wind loads due to the physical size of such structures. This paper contains the methodology and assessment of a project which set out to accomplish an improved method for modelling wind loads on a radar structure. The new method employs the use of computational fluid dynamics (CFD) to create a simulation of the conditions. Several studies on the approach to CFD testing were undertaken to optimise the process. Dimensions of domain volume and mesh density were examined for their effect on the computed solutions, as well as run time. Once an efficient set-up had been found, a scale model of the radar was analysed. Pressure distributions across the antenna face were studied from four cases, in which the prevailing wind approached from a different direction relative to the system (0°, 45°,90° and 180°). To validate the results from the CFD, a low-speed wind tunnel test was conducted. The experimental measurements were compared to the computed results and common trends were shown to exist between both sets of data.

  5. Mesoscale atmosphere ocean coupling enhances the transfer of wind energy into the ocean

    Science.gov (United States)

    Byrne, D.; Münnich, M.; Frenger, I.; Gruber, N.

    2016-01-01

    Although it is well established that the large-scale wind drives much of the world's ocean circulation, the contribution of the wind energy input at mesoscales (10–200 km) remains poorly known. Here we use regional simulations with a coupled high-resolution atmosphere–ocean model of the South Atlantic, to show that mesoscale ocean features and, in particular, eddies can be energized by their thermodynamic interactions with the atmosphere. Owing to their sea-surface temperature anomalies affecting the wind field above them, the oceanic eddies in the presence of a large-scale wind gradient provide a mesoscale conduit for the transfer of energy into the ocean. Our simulations show that this pathway is responsible for up to 10% of the kinetic energy of the oceanic mesoscale eddy field in the South Atlantic. The conditions for this pathway to inject energy directly into the mesoscale prevail over much of the Southern Ocean north of the Polar Front. PMID:27292447

  6. Statistical analysis of wind power in the region of Veracruz (Mexico)

    Energy Technology Data Exchange (ETDEWEB)

    Cancino-Solorzano, Yoreley [Departamento de Ing Electrica-Electronica, Instituto Tecnologico de Veracruz, Calzada Miguel A. de Quevedo 2779, 91860 Veracruz (Mexico); Xiberta-Bernat, Jorge [Departamento de Energia, Escuela Tecnica Superior de Ingenieros de Minas, Universidad de Oviedo, C/Independencia, 13, 2a Planta, 33004 Oviedo (Spain)

    2009-06-15

    The capacity of the Mexican electricity sector faces the challenge of satisfying the demand of the 80 GW forecast by 2016. This value supposes a steady yearly average increase of some 4.9%. The electricity sector increases for the next eight years will be mainly made up of combined cycle power plants which could be a threat to the energy supply of the country due to the fact that the country is not self-sufficient in natural gas. As an alternative wind energy resource could be a more suitable option compared with combined cycle power plants. This option is backed by market trends indicating that wind technology costs will continue to decrease in the near future as has happened in recent years. Evaluation of the eolic potential in different areas of the country must be carried out in order to achieve the best use possible of this option. This paper gives a statistical analysis of the wind characteristics in the region of Veracruz. The daily, monthly and annual wind speed values have been studied together with their prevailing direction. The data analyzed correspond to five meteorological stations and two anemometric stations located in the aforementioned area. (author)

  7. Statistical analysis of wind power in the region of Veracruz (Mexico)

    International Nuclear Information System (INIS)

    Cancino-Solorzano, Yoreley; Xiberta-Bernat, Jorge

    2009-01-01

    The capacity of the Mexican electricity sector faces the challenge of satisfying the demand of the 80 GW forecast by 2016. This value supposes a steady yearly average increase of some 4.9%. The electricity sector increases for the next eight years will be mainly made up of combined cycle power plants which could be a threat to the energy supply of the country due to the fact that the country is not self-sufficient in natural gas. As an alternative wind energy resource could be a more suitable option compared with combined cycle power plants. This option is backed by market trends indicating that wind technology costs will continue to decrease in the near future as has happened in recent years. Evaluation of the eolic potential in different areas of the country must be carried out in order to achieve the best use possible of this option. This paper gives a statistical analysis of the wind characteristics in the region of Veracruz. The daily, monthly and annual wind speed values have been studied together with their prevailing direction. The data analyzed correspond to five meteorological stations and two anemometric stations located in the aforementioned area. (author)

  8. Meteor wind observation at Kyoto Station

    International Nuclear Information System (INIS)

    Kato, S.; Aso, T.; Tsuda, T.

    1979-01-01

    Meteor wind observation at Kyoto Station has now collected a fairly large amount of data enough to enable to know the basic dynamic state at meteor heights over the station. Tidal and prevailing winds have been detected and their behavior seems now well understood on daily and seasonal basis. A comparison with observations at other stations suggests classical tidal theory to be relevant to explain the average state. Deviations from the mean present problems on the existence of various causes including hydromagnetic effects. Gravity waves would be an interesting subject in future study. (author)

  9. Evaluation of Urbanization Influences on Urban Winds of Kenyan ...

    African Journals Online (AJOL)

    There is need to understand the modification of wind since the wind spped and direction greatly affects dispersion of pollutants in the city and distribution of heat which affect human comfort. The study utilized land surface albedo, decadal population data and daily wind speeds and direction. The wind was analyzed using ...

  10. Magnetosheath waves under very low solar wind dynamic pressure: Wind/Geotail observations

    Directory of Open Access Journals (Sweden)

    C. J. Farrugia

    2005-06-01

    Full Text Available The expanded bow shock on and around "the day the solar wind almost disappeared" (11 May 1999 allowed the Geotail spacecraft to make a practically uninterrupted 54-h-long magnetosheath pass near dusk (16:30-21:11 magnetic local time at a radial distance of 24 to 30 RE (Earth radii. During most of this period, interplanetary parameters varied gradually and in such a way as to give rise to two extreme magnetosheath structures, one dominated by magnetohydrodynamic (MHD effects and the other by gas dynamic effects. We focus attention on unusual features of electromagnetic ion wave activity in the former magnetosheath state, and compare these features with those in the latter. Magnetic fluctuations in the gas dynamic magnetosheath were dominated by compressional mirror mode waves, and left- and right-hand polarized electromagnetic ion cyclotron (EIC waves transverse to the background field. In contrast, the MHD magnetosheath, lasting for over one day, was devoid of mirror oscillations and permeated instead by EIC waves of weak intensity. The weak wave intensity is related to the prevailing low solar wind dynamic pressures. Left-hand polarized EIC waves were replaced by bursts of right-hand polarized waves, which remained for many hours the only ion wave activity present. This activity occurred when the magnetosheath proton temperature anisotropy (= $T_{p, perp}/T_{p, parallel}{-}1$ became negative. This was because the weakened bow shock exposed the magnetosheath directly to the (negative temperature anisotropy of the solar wind. Unlike the normal case studied in the literature, these right-hand waves were not by-products of left-hand polarized waves but derived their energy source directly from the magnetosheath temperature anisotropy. Brief entries into the

  11. Magnetosheath waves under very low solar wind dynamic pressure: Wind/Geotail observations

    Directory of Open Access Journals (Sweden)

    C. J. Farrugia

    2005-06-01

    Full Text Available The expanded bow shock on and around "the day the solar wind almost disappeared" (11 May 1999 allowed the Geotail spacecraft to make a practically uninterrupted 54-h-long magnetosheath pass near dusk (16:30-21:11 magnetic local time at a radial distance of 24 to 30 RE (Earth radii. During most of this period, interplanetary parameters varied gradually and in such a way as to give rise to two extreme magnetosheath structures, one dominated by magnetohydrodynamic (MHD effects and the other by gas dynamic effects. We focus attention on unusual features of electromagnetic ion wave activity in the former magnetosheath state, and compare these features with those in the latter. Magnetic fluctuations in the gas dynamic magnetosheath were dominated by compressional mirror mode waves, and left- and right-hand polarized electromagnetic ion cyclotron (EIC waves transverse to the background field. In contrast, the MHD magnetosheath, lasting for over one day, was devoid of mirror oscillations and permeated instead by EIC waves of weak intensity. The weak wave intensity is related to the prevailing low solar wind dynamic pressures. Left-hand polarized EIC waves were replaced by bursts of right-hand polarized waves, which remained for many hours the only ion wave activity present. This activity occurred when the magnetosheath proton temperature anisotropy (= became negative. This was because the weakened bow shock exposed the magnetosheath directly to the (negative temperature anisotropy of the solar wind. Unlike the normal case studied in the literature, these right-hand waves were not by-products of left-hand polarized waves but derived their energy source directly from the magnetosheath temperature anisotropy. Brief entries into the low latitude boundary layer (LLBL and duskside magnetosphere occurred under such inflated conditions that the magnetospheric magnetic pressure was insufficient to maintain pressure balance. In these crossings, the inner edge of

  12. Current direction, marine toxic substances, and wind wave spectra data from moored current meter casts and other instruments in the Gulf of Mexico as part of the Brine Disposal project, 1977-09-15 to 1979-06-30 (NODC Accession 7900295)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, marine toxic substances, and wind wave spectra data were collected using moored current meter casts and other instruments in the Gulf of Mexico...

  13. Current direction, marine toxic substances, and wind wave spectra data from moored current meter casts and other instruments in the Gulf of Mexico as part of the Brine Disposal project, 1977-12-22 to 1979-09-30 (NODC Accession 7900336)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, marine toxic substances, and wind wave spectra data were collected using moored current meter casts and other instruments in the Gulf of Mexico...

  14. Air pollution in a tropical city: the relationship between wind direction and lichen bio-indicators in San José, Costa Rica.

    Science.gov (United States)

    Bustamante, Erich Neurohr; Monge-Nájera, Julián; González Lutz, María Isabel

    2011-06-01

    Lichens are good bio-indicators of air pollution, but in most tropical countries there are few studies on the subject; however, in the city of San José, Costa Rica, the relationship between air pollution and lichens has been studied for decades. In this article we evaluate the hypothesis that air pollution is lower where the wind enters the urban area (Northeast) and higher where it exits San José (Southwest). We identified the urban parks with a minimum area of approximately 5,000 m2 and randomly selected a sample of 40 parks located along the passage of wind through the city. To measure lichen coverage, we applied a previously validated 10 x 20 cm template with 50 random points to five trees per park (1.5m above ground, to the side with most lichens). Our results (years 2008 and 2009) fully agree with the generally accepted view that lichens reflect air pollution carried by circulating air masses. The practical implication is that the air enters the city relatively clean by the semi-rural and economically middle class area of Coronado, and leaves through the developed neighborhoods of Escazú and Santa Ana with a significant amount of pollutants. In the dry season, the live lichen coverage of this tropical city was lower than in the May to December rainy season, a pattern that contrasts with temperate habitats; but regardless of the season, pollution follows the pattern of wind movement through the city.

  15. Soil slip/debris flow localized by site attributes and wind-driven rain in the San Francisco Bay region storm of January 1982

    Science.gov (United States)

    Pike, R.J.; Sobieszczyk, S.

    2008-01-01

    GIS analysis at 30-m resolution reveals that effectiveness of slope-destabilizing processes in the San Francisco Bay area varies with compass direction. Nearly half the soil slip/debris flows mapped after the catastrophic rainstorm of 3-5 January 1982 occurred on slopes that face S to WSW, whereas fewer than one-quarter have a northerly aspect. Azimuthal analysis of hillside properties for susceptible terrain near the city of Oakland suggests that the skewed aspect of these landslides primarily reflects vegetation type, ridge and valley alignment, and storm-wind direction. Bedrock geology, soil expansivity, and terrain height and gradient also were influential but less so; the role of surface curvature is not wholly resolved. Normalising soil-slip aspect by that of the region's NNW-striking topography shifts the modal azimuth of soil-slip aspect from SW to SE, the direction of origin of winds during the 1982 storm-but opposite that of the prevailing WNW winds. Wind from a constant direction increases rainfall on windward slopes while diminishing it on leeward slopes, generating a modelled difference in hydrologically effective rainfall of up to 2:1 on steep hillsides in the Oakland area. This contrast is consistent with numerical simulations of wind-driven rain and with rainfall thresholds for debris-flow activity. We conclude that storm winds from the SE in January 1982 raised the vulnerability of the Bay region's many S-facing hillsides, most of which are covered in shallow-rooted shrub and grass that offer minimal resistance to soil slip. Wind-driven rainfall also appears to have controlled debris-flow location in a major 1998 storm and probably others. Incorporating this overlooked influence into GIS models of debris-flow likelihood would improve predictions of the hazard in central California and elsewhere.

  16. Floating wind turbine system

    Science.gov (United States)

    Viterna, Larry A. (Inventor)

    2009-01-01

    A floating wind turbine system with a tower structure that includes at least one stability arm extending therefrom and that is anchored to the sea floor with a rotatable position retention device that facilitates deep water installations. Variable buoyancy for the wind turbine system is provided by buoyancy chambers that are integral to the tower itself as well as the stability arm. Pumps are included for adjusting the buoyancy as an aid in system transport, installation, repair and removal. The wind turbine rotor is located downwind of the tower structure to allow the wind turbine to follow the wind direction without an active yaw drive system. The support tower and stability arm structure is designed to balance tension in the tether with buoyancy, gravity and wind forces in such a way that the top of the support tower leans downwind, providing a large clearance between the support tower and the rotor blade tips. This large clearance facilitates the use of articulated rotor hubs to reduced damaging structural dynamic loads. Major components of the turbine can be assembled at the shore and transported to an offshore installation site.

  17. 5 CFR 532.205 - The use of Federal, State, and local minimum wage requirements in determining prevailing rates.

    Science.gov (United States)

    2010-01-01

    ... minimum wage requirements in determining prevailing rates. 532.205 Section 532.205 Administrative... Determinations § 532.205 The use of Federal, State, and local minimum wage requirements in determining prevailing... amended, or (2) The highest State or local minimum wage rate in the local wage area which is applicable to...

  18. Applicability of Synthetic Aperture Radar Wind Retrievals on Offshore Wind Resources Assessment in Hangzhou Bay, China

    DEFF Research Database (Denmark)

    Chang, Rui; Zhu, Rong; Badger, Merete

    2014-01-01

    ENVISAT advanced SAR (ASAR) for mapping wind resources with high spatial resolution. Around 181 collected pairs of wind data from SAR wind maps and from 13 meteorological stations in Hangzhou Bay are compared. The statistical results comparing in situ wind speed and SAR-based wind speed show a standard...... deviation (SD) of 1.99 m/s and correlation coefficient of R = 0.67. The model wind directions, which are used as input for the SAR wind speed retrieval, show a high correlation coefficient (R = 0.89) but a large standard deviation (SD = 42.3°) compared to in situ observations. The Weibull probability...

  19. Winds observed in the Northern European seas with wind lidars, meteorological masts and satellite

    DEFF Research Database (Denmark)

    Hasager, Charlotte Bay; Stein, D.; Peña, Alfredo

    2013-01-01

    of them for up to two years when the project campaign ended. The NORSEWInD database on lidar data in total contains around 11 years worth of observations (> 280.000 10 min data). The wind lidars were mounted such that winds were mapped at or very near 100 m above sea level. The lidars provide wind profile...... directional bins. The latter resulted in so-called ‘alpha roses’, similar to wind roses but with the values of alpha given. Satellite ocean surface winds were collected from synthetic aperture radar (SAR), scatterometer and passive microwave instruments. All satellite wind data provide winds at 10 m above sea...

  20. Wind resource in the urban environment

    Directory of Open Access Journals (Sweden)

    Derek Joseph Kearney

    2013-10-01

    Full Text Available Renewable energy technologies, such as wind turbines, have to be considered for new building over 1000m2 under the Energy Performance of Buildings Directive (2002. Accurate assessment of the wind resource is a key component in the success of a wind installation. Designers, planners and architects also need wind data from urban areas to support low-energy building design, natural ventilation, air quality, pollution control, insurance and wind engineering. Over the last six years instrumentation has been installed at the Dublin Institute of Technology (DIT in two separate locations to monitor the wind. The data has shown that the wind resource will vary quite considerably on a given site and this is due to local variations in topography, and other factors associated with wind and turbulence in the built environment. Difficulties were encountered in measuring the wind and turbulence on site. IEC 61400-12-1: 2005 states that “... analytical tools (anemometers presently available offer little help in identifying the impact of these variables, and experimental methods encounter equally-serious difficulties.” The practical experience of measuring wind in the urban environment informed the development of a prototype anemometer that may be capable of digitally mapping accurate real-time three-dimensional data on wind speed, wind direction and, uniquely in the field of wind instrumentation, wind turbulence.

  1. Wind turbine noise diagnostics

    International Nuclear Information System (INIS)

    Richarz, W.; Richarz, H.

    2009-01-01

    This presentation proposed a self-consistent model for broad-band noise emitted from modern wind turbines. The simple source model was consistent with the physics of sound generation and considered the unique features of wind turbines. Although the acoustics of wind turbines are similar to those of conventional propellers, the dimensions of wind turbines pose unique challenges in diagnosing noise emission. The general features of the sound field were deduced. Source motion and source directivity appear to be responsible for amplitude variations. The amplitude modulation is likely to make wind-turbine noise more audible, and may be partly responsible for annoyance that has been reported in the literature. Acoustic array data suggests that broad-band noise is emitted predominantly during the downward sweep of each rotor blade. Source motion and source directivity account for the observed pattern. Rotor-tower interaction effects are of lesser importance. Predicted amplitude modulation ranges from 1 dB to 6dB. 2 refs., 9 figs.

  2. 49 CFR 193.2067 - Wind forces.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Wind forces. 193.2067 Section 193.2067...: FEDERAL SAFETY STANDARDS Siting Requirements § 193.2067 Wind forces. (a) LNG facilities must be designed to withstand without loss of structural or functional integrity: (1) The direct effect of wind forces...

  3. Wind energy

    CERN Document Server

    Woll, Kris

    2016-01-01

    Across the country, huge open spaces are covered in gently turning wind turbines. In Wind Energy, explore how these machines generate electricity, learn about the history of wind power, and discover the latest advances in the field. Easy-to-read text, vivid images, and helpful back matter give readers a clear look at this subject. Features include a table of contents, infographics, a glossary, additional resources, and an index. Aligned to Common Core Standards and correlated to state standards. Core Library is an imprint of Abdo Publishing, a division of ABDO.

  4. Air pollution in a tropical city: the relationship between wind direction and lichen bio-indicators in San José, Costa Rica

    Directory of Open Access Journals (Sweden)

    Erich Neurohr Bustamante

    2011-06-01

    Full Text Available Lichens are good bio-indicators of air pollution, but in most tropical countries there are few studies on the subject; however, in the city of San José, Costa Rica, the relationship between air pollution and lichens has been studied for decades. In this article we evaluate the hypothesis that air pollution is lower where the wind enters the urban area (Northeast and higher where it exits San José (Southwest. We identified the urban parks with a minimum area of approximately 5 000m² and randomly selected a sample of 40 parks located along the passage of wind through the city. To measure lichen coverage, we applied a previously validated 10 x 20cm template with 50 random points to five trees per park (1.5m above ground, to the side with most lichens. Our results (years 2008 and 2009 fully agree with the generally accepted view that lichens reflect air pollution carried by circulating air masses. The practical implication is that the air enters the city relatively clean by the semi-rural and economically middle class area of Coronado, and leaves through the developed neighborhoods of Escazú and Santa Ana with a significant amount of pollutants. In the dry season, the live lichen coverage of this tropical city was lower than in the May to December rainy season, a pattern that contrasts with temperate habitats; but regardless of the season, pollution follows the pattern of wind movement through the city. Rev.Biol. Trop. 59 (2: 899-905. Epub 2011 June 01.

  5. Careers in Industry: Pioneering Spirit Prevails at the Carlsberg Research Laboratory.

    Science.gov (United States)

    Skadhauge, Birgitte; Haldrup, Anna; Olsen, Ole

    2016-10-01

    The founder of the Carlsberg brewery, J.C Jacobsen, recognized the value of private-public partnership and established the Carlsberg Foundation in 1876 with the single aim of applying research and innovation to brew the best beer. One hundred and forty years on, Jacobsen's vision still prevails, and in this interview three scientists from the Carlsberg Research Laboratory (Birgitte Skadhauge, Anna Haldrup, and Ole Olsen) share their experience about finding a career at the crossroads between industry and basic research. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Establishing a Comprehensive Wind Energy Program

    Energy Technology Data Exchange (ETDEWEB)

    Fleeter, Sanford [Purdue University

    2012-09-30

    This project was directed at establishing a comprehensive wind energy program in Indiana, including both educational and research components. A graduate/undergraduate course ME-514 - Fundamentals of Wind Energy has been established and offered and an interactive prediction of VAWT performance developed. Vertical axis wind turbines for education and research have been acquired, instrumented and installed on the roof top of a building on the Calumet campus and at West Lafayette (Kepner Lab). Computational Fluid Dynamics (CFD) calculations have been performed to simulate these urban wind environments. Also, modal dynamic testing of the West Lafayette VAWT has been performed and a novel horizontal axis design initiated. The 50-meter meteorological tower data obtained at the Purdue Beck Agricultural Research Center have been analyzed and the Purdue Reconfigurable Micro Wind Farm established and simulations directed at the investigation of wind farm configurations initiated. The virtual wind turbine and wind turbine farm simulation in the Visualization Lab has been initiated.

  7. Cooperation under the RES Directive - Case study on a joint project: An offshore wind park in the North Sea (cooperation between the Netherlands, Belgium, UK, and Luxembourg)

    DEFF Research Database (Denmark)

    Kitzing, Lena; Nysten, Jana; Gephart, Malte

    assume that Belgium can achieve to involve Luxembourg into the project viastatistical transfers, corresponding to 10% of the project.Because of the first mover character of such a joint project in the North Sea, with offshore electricityproduction connected to several countries, we discuss in detail...... as compared to own development at the same site. The UK will gain anoption on additional offshore wind resources that may be at competitive prices. Luxembourg mighthave a benefit from using a concrete joint project for the import of RES benefits, as they are moretangible than for e.g. technology...

  8. 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.

  9. The economics of wind energy. Collection of papers for discussions

    International Nuclear Information System (INIS)

    Vihriaelae, H.

    1995-01-01

    This publication contains the proceedings of EWEA Special Topic Conference '95 on the economics of wind energy, held in Helsinki, Finland, on 5-7 September, 1995. The programme consisted of panel discussions and poster presentations on National Programmes and Operational Experience of Wind Energy, Grid Issues and Avoided Direct Costs of Wind Energy, Avoided External Costs of Wind Energy, The Role of Wind Energy in Future Energy Supply and Technical Innovations of Wind Energy

  10. The economics of wind energy. Collection of papers for discussions

    Energy Technology Data Exchange (ETDEWEB)

    Vihriaelae, H. [ed.

    1995-12-31

    This publication contains the proceedings of EWEA Special Topic Conference `95 on the economics of wind energy, held in Helsinki, Finland, on 5-7 September, 1995. The programme consisted of panel discussions and poster presentations on National Programmes and Operational Experience of Wind Energy, Grid Issues and Avoided Direct Costs of Wind Energy, Avoided External Costs of Wind Energy, The Role of Wind Energy in Future Energy Supply and Technical Innovations of Wind Energy

  11. Some atmospheric dispersion, wind and temperature statistics from Jervis Bay, Australian Capital Territory 1972 to 1974

    International Nuclear Information System (INIS)

    Clark, G.H.

    1985-07-01

    A meteorological study of winds, temperatures and Pasquill stability categories was conducted in the coastal conditions at Jervis Bay. Three Pasquill stability categorisation schemes were compared. These indicated a predominance of neutral to slightly unstable conditions. During the daytime, north bay breezes and north-east sea breezes were most common together with on-shore south-east winds. Off-shore south-west winds prevailed during winter and were observed most frequently at night

  12. World Wind

    Data.gov (United States)

    National Aeronautics and Space Administration — World Wind allows any user to zoom from satellite altitude into any place on Earth, leveraging high resolution LandSat imagery and SRTM elevation data to experience...

  13. Method and apparatus for wind turbine braking

    Science.gov (United States)

    Barbu, Corneliu [Laguna Hills, CA; Teichmann, Ralph [Nishkayuna, NY; Avagliano, Aaron [Houston, TX; Kammer, Leonardo Cesar [Niskayuna, NY; Pierce, Kirk Gee [Simpsonville, SC; Pesetsky, David Samuel [Greenville, SC; Gauchel, Peter [Muenster, DE

    2009-02-10

    A method for braking a wind turbine including at least one rotor blade coupled to a rotor. The method includes selectively controlling an angle of pitch of the at least one rotor blade with respect to a wind direction based on a design parameter of a component of the wind turbine to facilitate reducing a force induced into the wind turbine component as a result of braking.

  14. Assessment of Wind Parameter Sensitivity on Ultimate and Fatigue Wind Turbine Loads: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, Amy N [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Sethuraman, Latha [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Jonkman, Jason [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Quick, Julian [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2018-02-13

    Wind turbines are designed using a set of simulations to ascertain the structural loads that the turbine could encounter. While mean hub-height wind speed is considered to vary, other wind parameters such as turbulence spectra, sheer, veer, spatial coherence, and component correlation are fixed or conditional values that, in reality, could have different characteristics at different sites and have a significant effect on the resulting loads. This paper therefore seeks to assess the sensitivity of different wind parameters on the resulting ultimate and fatigue loads on the turbine during normal operational conditions. Eighteen different wind parameters are screened using an Elementary Effects approach with radial points. As expected, the results show a high sensitivity of the loads to the turbulence standard deviation in the primary wind direction, but the sensitivity to wind shear is often much greater. To a lesser extent, other wind parameters that drive loads include the coherence in the primary wind direction and veer.

  15. Assessment of Wind Parameter Sensitivity on Extreme and Fatigue Wind Turbine Loads

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, Amy N [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Sethuraman, Latha [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Jonkman, Jason [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Quick, Julian [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2018-01-12

    Wind turbines are designed using a set of simulations to ascertain the structural loads that the turbine could encounter. While mean hub-height wind speed is considered to vary, other wind parameters such as turbulence spectra, sheer, veer, spatial coherence, and component correlation are fixed or conditional values that, in reality, could have different characteristics at different sites and have a significant effect on the resulting loads. This paper therefore seeks to assess the sensitivity of different wind parameters on the resulting ultimate and fatigue loads on the turbine during normal operational conditions. Eighteen different wind parameters are screened using an Elementary Effects approach with radial points. As expected, the results show a high sensitivity of the loads to the turbulence standard deviation in the primary wind direction, but the sensitivity to wind shear is often much greater. To a lesser extent, other wind parameters that drive loads include the coherence in the primary wind direction and veer.

  16. On the Relationship between Solar Wind Speed, Earthward-Directed Coronal Mass Ejections, Geomagnetic Activity, and the Sunspot Cycle Using 12-Month Moving Averages

    Science.gov (United States)

    Wilson, Robert M.; Hathaway, David H.

    2008-01-01

    For 1996 .2006 (cycle 23), 12-month moving averages of the aa geomagnetic index strongly correlate (r = 0.92) with 12-month moving averages of solar wind speed, and 12-month moving averages of the number of coronal mass ejections (CMEs) (halo and partial halo events) strongly correlate (r = 0.87) with 12-month moving averages of sunspot number. In particular, the minimum (15.8, September/October 1997) and maximum (38.0, August 2003) values of the aa geomagnetic index occur simultaneously with the minimum (376 km/s) and maximum (547 km/s) solar wind speeds, both being strongly correlated with the following recurrent component (due to high-speed streams). The large peak of aa geomagnetic activity in cycle 23, the largest on record, spans the interval late 2002 to mid 2004 and is associated with a decreased number of halo and partial halo CMEs, whereas the smaller secondary peak of early 2005 seems to be associated with a slight rebound in the number of halo and partial halo CMEs. Based on the observed aaM during the declining portion of cycle 23, RM for cycle 24 is predicted to be larger than average, being about 168+/-60 (the 90% prediction interval), whereas based on the expected aam for cycle 24 (greater than or equal to 14.6), RM for cycle 24 should measure greater than or equal to 118+/-30, yielding an overlap of about 128+/-20.

  17. Moment of Inertia Dependence of Vertical Axis Wind Turbines in Pulsating Winds

    Directory of Open Access Journals (Sweden)

    Yutaka Hara

    2012-01-01

    Full Text Available Vertical Axis Wind Turbines (VAWTs are unaffected by changes in wind direction, and they have a simple structure and the potential for high efficiency due to their lift driving force. However, VAWTs are affected by changes in wind speed, owing to effects originating from the moment of inertia. In this study, changes in the rotational speed of a small VAWT in pulsating wind, generated by an unsteady wind tunnel, are investigated by varying the wind cycle and amplitude parameters. It is shown that the responses observed experimentally agree with simulations based on torque characteristics obtained under steady rotational conditions. Additionally, a simple equation expressing the relationship between the rotational change width and amplitude of the pulsating wind is presented. The energy efficiency in a pulsating wind remains constant with changes in both the moment of inertia and the wind cycle; however, the energy efficiency decreases when the wind amplitude is large.

  18. 78 FR 29364 - Exelon Corporation, Exelon Wind 1, LLC, Exelon Wind 2, LLC, Exelon Wind 3, LLC, Exelon Wind 4...

    Science.gov (United States)

    2013-05-20

    ...-005, QF07-257-004] Exelon Corporation, Exelon Wind 1, LLC, Exelon Wind 2, LLC, Exelon Wind 3, LLC, Exelon Wind 4, LLC, Exelon Wind 5, LLC, Exelon Wind 6, LLC, Exelon Wind 7, LLC, Exelon Wind 8, LLC, Exelon Wind 9, LLC, Exelon Wind 10, LLC, Exelon Wind 11, LLC, High Plains Wind Power, LLC v. Xcel Energy...

  19. Coastal Ohio Wind Project

    Energy Technology Data Exchange (ETDEWEB)

    Gorsevski, Peter [Bowling Green State Univ., OH (United States); Afjeh, Abdollah [Univ. of Toledo, OH (United States); Jamali, Mohsin [Univ. of Toledo, OH (United States); Bingman, Verner [Bowling Green State Univ., OH (United States)

    2014-04-04

    to collect additional monitoring parameters such as passage rates, flight paths, flight directions, and flight altitudes of nocturnal migrating species. Our work focused on the design and development of custom built marine radar that used t-bar and parabolic dish antennas. The marine radar used in the project was Furuno (XANK250) which was coupled with a XIR3000B digitizing card from Russell Technologies for collection of the radar data. The radar data was processed by open source radR processing software using different computational techniques and methods. Additional data from thermal IR imaging cameras were collected to detect heat emitted from objects and provide information on movements of birds and bats, data which we used for different animal flight behavior analysis. Lastly, the data from the acoustic recorders were used to provide the number of bird calls for assessing patterns and peak passage rates during migration. The development of the geospatial database included collection of different data sources that are used to support offshore wind turbine development. Many different data sets were collected and organized using initial version of web-based repository software tools that can accommodate distribution of rectified pertinent data sets such as the lake depth, lake bottom engineering parameters, extent of ice, navigation pathways, wind speed, important bird habitats, fish efforts and other layers that are relevant for supporting robust offshore wind turbine developments. Additional geospatial products developed during the project included few different prototypes for offshore wind farm suitability which can involve different stakeholders and participants for solving complex planning problems and building consensus. Some of the prototypes include spatial decision support system (SDSS) for collaborative decision making, a web-based Participatory Geographic Information System (PGIS) framework for evaluating importance of different decision alternatives

  20. Superconducting wind turbine generators

    DEFF Research Database (Denmark)

    Abrahamsen, Asger Bech; Mijatovic, Nenad; Seiler, Eugen

    2010-01-01

    We have examined the potential of 10 MW superconducting direct drive generators to enter the European offshore wind power market and estimated that the production of about 1200 superconducting turbines until 2030 would correspond to 10% of the EU offshore market. The expected properties of future...... offshore turbines of 8 and 10 MW have been determined from an up-scaling of an existing 5 MW turbine and the necessary properties of the superconducting drive train are discussed. We have found that the absence of the gear box is the main benefit and the reduced weight and size is secondary. However......, the main challenge of the superconducting direct drive technology is to prove that the reliability is superior to the alternative drive trains based on gearboxes or permanent magnets. A strategy of successive testing of superconducting direct drive trains in real wind turbines of 10 kW, 100 kW, 1 MW and 10...

  1. 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.

  2. 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.

  3. Financing wind energy projects

    International Nuclear Information System (INIS)

    Blom, P.

    1996-01-01

    Triodos Bank has more than 10 years of experience with developing and financing wind projects in the Netherlands. Over 50 Megawatt has been installed with direct involvement of the bank. The experience is both as a bank and as a venture capital fund. In this contribution the perspective will be more from a venture capital point of view than as a bank. The bank's activities in the wind energy sector started in 1986 by forming a joint venture with an engineering bureau, experienced i wind energy but not yet in developing wind projects. From 1989 onwards the joint venture started to build wind farms, both as a private company and in a joint venture with utilities. The European Investment Bank became involved with a long-term debt finance facility (15 years, fixed interest loan). The main difficulties were long-term commitments from landowners (Dike authorities) and utilities with regard to power contracts. The development got really stuck when utilities refused to pay a fair price anymore. Also, site development became more and more difficult. Even the poor technical performance improved drastically and did not frighten developers and banks too much. (author)

  4. Effects of an electromagnetic shield and armature teeth on the short-circuit performance of a direct drive superconducting generator for 10 MW wind turbines

    DEFF Research Database (Denmark)

    Liu, Dong; Polinder, Henk; Abrahamsen, Asger Bech

    2015-01-01

    reactance. An electromagnetic (EM) shield between the rotor and the stator as well as iron or non-magnetic composite (NMC) armature teeth affects the sub-transient reactance of a superconducting machine so that they play a role in the short-circuit performance of a superconducting wind generator. This paper...... presents a 10 MW superconducting generator design and studies the effects of material, thickness and position of an EM shield and the effects of NMC and iron armature teeth on the torque and the field current density during a three-phase short circuit at the generator terminal. One result shows...... that the short circuit torque is not able to be effectively reduced by varying the EM shield and the armature tooth material. The other result shows that the field current density is likely to exceed its critical value during a short circuit although the EM shield material and the armature tooth material take...

  5. Demonstration of a Basis for Tall Wind Turbine Design, EUDP Project Final Report

    DEFF Research Database (Denmark)

    Natarajan, Anand; Dimitrov, Nikolay Krasimirov; Madsen, Peter Hauge

    Wind turbine design using calibrated wind models have been proposed to be used in conjunction with load cases which lead to reduced uncertainties in the design of wind turbines with hub heights above 60m. These recommended wind profiles have been made for shear, wind directional change and turbul......Wind turbine design using calibrated wind models have been proposed to be used in conjunction with load cases which lead to reduced uncertainties in the design of wind turbines with hub heights above 60m. These recommended wind profiles have been made for shear, wind directional change...

  6. Optimization of Wind Farm Layout in Complex Terrain

    DEFF Research Database (Denmark)

    Xu, Chang; Yang, Jianchuan; Li, Chenqi

    2013-01-01

    distribution law and wake loss between different turbines into consideration and calculated the sheltering area effect of wake loss from upstream wind turbines on downstream wind turbines. Wind direction was divided into sixteen sections, and the wind speed was processed by the Weibull distribution....... To calculate the output of each section, we used the wind speed distribution and its probability density as well as the wake loss between wind turbines for every section. The objective function is maximization of the whole wind farm's power output and the free variables are the wind turbines' coordinates which...

  7. WIND TURBINES FOR WIND POWER INSTALLATIONS

    Directory of Open Access Journals (Sweden)

    Barladean A.S.

    2008-04-01

    Full Text Available The problem of wind turbine choice for wind power stations is examined in this paper. It is shown by comparison of parameters and characteristics of wind turbines, that for existing modes and speeds of wind in territory of Republic of Moldova it is necessary to use multi-blade small speed rotation wind turbines of fan class.

  8. Suprathermal electron loss cone distributions in the solar wind: Ulysses observations

    International Nuclear Information System (INIS)

    Phillips, J. L.; Feldman, W. C.; Gosling, J. T.; Hammond, C. M.; Forsyth, R. J.

    1996-01-01

    We present observations by the Ulysses solar wind plasma experiment of a new class of suprathermal electron signatures. At low solar latitudes and heliocentric distances beyond 3.37 AU Ulysses encountered seven intervals, ranging in duration from 1 hour to 22 hours, in which the suprathermal distributions included an antisunward field-aligned beam and a return population with a flux dropout typically spanning ±60 deg. from the sunward field-aligned direction. All events occurred between the forward and reverse shocks or waves bounding corotating interaction regions (CIRs). The observations support a scenario in which the sunward-moving electrons result from reflection of the prevailing antisunward field-aligned beam at magnetic field compressions downstream from the spacecraft, with wide loss cones caused by the relatively weak mirror ratio. This hypothesis requires that the field magnitude within the CIRs actually increased locally with increasing field-aligned distance from the Sun

  9. 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.

  10. Wind turbine

    Science.gov (United States)

    Cheney, Jr., Marvin C.

    1982-01-01

    A wind turbine of the type having an airfoil blade (15) mounted on a flexible beam (20) and a pitch governor (55) which selectively, torsionally twists the flexible beam in response to wind turbine speed thereby setting blade pitch, is provided with a limiter (85) which restricts unwanted pitch change at operating speeds due to torsional creep of the flexible beam. The limiter allows twisting of the beam by the governor under excessive wind velocity conditions to orient the blades in stall pitch positions, thereby preventing overspeed operation of the turbine. In the preferred embodiment, the pitch governor comprises a pendulum (65,70) which responds to changing rotor speed by pivotal movement, the limiter comprising a resilient member (90) which engages an end of the pendulum to restrict further movement thereof, and in turn restrict beam creep and unwanted blade pitch misadjustment.

  11. Using Satellite SAR to Characterize the Wind Flow around Offshore Wind Farms

    Directory of Open Access Journals (Sweden)

    Charlotte Bay Hasager

    2015-06-01

    Full Text Available Offshore wind farm cluster effects between neighboring wind farms increase rapidly with the large-scale deployment of offshore wind turbines. The wind farm wakes observed from Synthetic Aperture Radar (SAR are sometimes visible and atmospheric and wake models are here shown to convincingly reproduce the observed very long wind farm wakes. The present study mainly focuses on wind farm wake climatology based on Envisat ASAR. The available SAR data archive covering the large offshore wind farms at Horns Rev has been used for geo-located wind farm wake studies. However, the results are difficult to interpret due to mainly three issues: the limited number of samples per wind directional sector, the coastal wind speed gradient, and oceanic bathymetry effects in the SAR retrievals. A new methodology is developed and presented. This method overcomes effectively the first issue and in most cases, but not always, the second. In the new method all wind field maps are rotated such that the wind is always coming from the same relative direction. By applying the new method to the SAR wind maps, mesoscale and microscale model wake aggregated wind-fields results are compared. The SAR-based findings strongly support the model results at Horns Rev 1.

  12. Effects of Yaw Error on Wind Turbine Running Characteristics Based on the Equivalent Wind Speed Model

    Directory of Open Access Journals (Sweden)

    Shuting Wan

    2015-06-01

    Full Text Available Natural wind is stochastic, being characterized by its speed and direction which change randomly and frequently. Because of the certain lag in control systems and the yaw body itself, wind turbines cannot be accurately aligned toward the wind direction when the wind speed and wind direction change frequently. Thus, wind turbines often suffer from a series of engineering issues during operation, including frequent yaw, vibration overruns and downtime. This paper aims to study the effects of yaw error on wind turbine running characteristics at different wind speeds and control stages by establishing a wind turbine model, yaw error model and the equivalent wind speed model that includes the wind shear and tower shadow effects. Formulas for the relevant effect coefficients Tc, Sc and Pc were derived. The simulation results indicate that the effects of the aerodynamic torque, rotor speed and power output due to yaw error at different running stages are different and that the effect rules for each coefficient are not identical when the yaw error varies. These results may provide theoretical support for optimizing the yaw control strategies for each stage to increase the running stability of wind turbines and the utilization rate of wind energy.

  13. El suicidio: Una conducta antisocial que prevalece/Suicide: An antisocial behavior that prevails

    Directory of Open Access Journals (Sweden)

    Omar Alejandro De León Palomo

    2012-01-01

    Full Text Available The suicide has existed throughout history and has prevailed as a behavior that was contrary to the rules of the society in terms of preservation of life itself; the objective of this research was to make emphasis on the nature of antisocial behavior of this behavior and show its prevalence in the years 2006 to 2010 in Mexico and Tamaulipas, as well as from 1999 to 2008 in Reynosa, Tamaulipas. For which the data were obtained from the National Institute of Statistics and Geography to the country and the State and the books of the register of deaths by cause violent of the Regional Unit of Expert Services of the Attorney General of Justice, which has its headquarters in Reynosa; developed a theoretical framework on the impact of the conduct in society and the means to prevent it, The data obtained we revealed the continued presence of this conduct year-on-year, 23.554 cases appearing in Mexico and 819 in Tamaulipas in the period from 2006 to 2010; in Reynosa, Tamaulipas were presented 278 suicides in the period 1999 to 2008. The results show us a conduct stable in numbers, but without excessive overflows that prevails year-on-year, suicide, and the attempt of the same should be viewed as a social problem and not detract from the importance that it deserves a conduct of these dimensions, that is no more than a reflection of the situation in which are the means of social control toward the preservation of life itself.

  14. Doppler Lidar Wind Value-Added Product

    Energy Technology Data Exchange (ETDEWEB)

    Newsom, R. K. [DOE ARM Climate Research Facility, Washington, DC (United States); Sivaraman, C. [DOE ARM Climate Research Facility, Washington, DC (United States); Shippert, T. R. [DOE ARM Climate Research Facility, Washington, DC (United States); Riihimaki, L. D. [DOE ARM Climate Research Facility, Washington, DC (United States)

    2015-07-01

    Wind speed and direction, together with pressure, temperature, and relative humidity, are the most fundamental atmospheric state parameters. Accurate measurement of these parameters is crucial for numerical weather prediction. Vertically resolved wind measurements in the atmospheric boundary layer are particularly important for modeling pollutant and aerosol transport. Raw data from a scanning coherent Doppler lidar system can be processed to generate accurate height-resolved measurements of wind speed and direction in the atmospheric boundary layer.

  15. Air pollution in a tropical city: the relationship between wind direction and lichen bio-indicators in San José, Costa Rica

    Directory of Open Access Journals (Sweden)

    Erich Neurohr Bustamante

    2011-06-01

    Full Text Available Lichens are good bio-indicators of air pollution, but in most tropical countries there are few studies on the subject; however, in the city of San José, Costa Rica, the relationship between air pollution and lichens has been studied for decades. In this article we evaluate the hypothesis that air pollution is lower where the wind enters the urban area (Northeast and higher where it exits San José (Southwest. We identified the urban parks with a minimum area of approximately 5 000m² and randomly selected a sample of 40 parks located along the passage of wind through the city. To measure lichen coverage, we applied a previously validated 10 x 20cm template with 50 random points to five trees per park (1.5m above ground, to the side with most lichens. Our results (years 2008 and 2009 fully agree with the generally accepted view that lichens reflect air pollution carried by circulating air masses. The practical implication is that the air enters the city relatively clean by the semi-rural and economically middle class area of Coronado, and leaves through the developed neighborhoods of Escazú and Santa Ana with a significant amount of pollutants. In the dry season, the live lichen coverage of this tropical city was lower than in the May to December rainy season, a pattern that contrasts with temperate habitats; but regardless of the season, pollution follows the pattern of wind movement through the city. Rev.Biol. Trop. 59 (2: 899-905. Epub 2011 June 01.Los líquenes constituyen un buen bioindicador para estudiar la “salud de la atmósfera”, pero en los países tropicales hay pocos estudios sobre el tema, aunque para la ciudad de San José existen algunos estudios sobre la relación entre tráfico vehicular y contaminación atmosférica. En este artículo evaluamos la hipótesis de que la contaminación atmosférica es menor en las áreas por donde ingresan los vientos a la zona urbana de San José (noreste y mayor a su salida (suroeste, para

  16. Dynamic modeling and simulation of wind turbines

    International Nuclear Information System (INIS)

    Ghafari Seadat, M.H.; Kheradmand Keysami, M.; Lari, H.R.

    2002-01-01

    Using wind energy for generating electricity in wind turbines is a good way for using renewable energies. It can also help to protect the environment. The main objective of this paper is dynamic modeling by energy method and simulation of a wind turbine aided by computer. In this paper, the equations of motion are extracted for simulating the system of wind turbine and then the behavior of the system become obvious by solving the equations. The turbine is considered with three blade rotor in wind direction, induced generator that is connected to the network and constant revolution for simulation of wind turbine. Every part of the wind turbine should be simulated for simulation of wind turbine. The main parts are blades, gearbox, shafts and generator

  17. Bringing satellite winds to hub-height

    DEFF Research Database (Denmark)

    Badger, Merete; Pena Diaz, Alfredo; Bredesen, Rolv Erlend

    2012-01-01

    Satellite observations of the ocean surface can provide detailed information about the spatial wind variability over large areas. This is very valuable for the mapping of wind resources offshore where other measurements are costly and sparse. Satellite sensors operating at microwave frequencies...... measure the amount of radar backscatter from the sea surface, which is a function of the instant wind speed, wind direction, and satellite viewing geometry. A major limitation related to wind retrievals from satellite observations is that existing empirical model functions relate the radar backscatter...... to wind speed at the height 10 m only. The extrapolation of satellite wind fields to higher heights, which are more relevant for wind energy, remains a challenge which cannot be addressed by means of satellite data alone. As part of the EU-NORSEWInD project (2008-12), a hybrid method has been developed...

  18. Astrospheres and Solar-like Stellar Winds

    Directory of Open Access Journals (Sweden)

    Wood Brian E.

    2004-07-01

    Full Text Available Stellar analogs for the solar wind have proven to be frustratingly difficult to detect directly. However, these stellar winds can be studied indirectly by observing the interaction regions carved out by the collisions between these winds and the interstellar medium (ISM. These interaction regions are called "astrospheres", analogous to the "heliosphere" surrounding the Sun. The heliosphere and astrospheres contain a population of hydrogen heated by charge exchange processes that can produce enough H I Ly alpha absorption to be detectable in UV spectra of nearby stars from the Hubble Space Telescope (HST. The amount of astrospheric absorption is a diagnostic for the strength of the stellar wind, so these observations have provided the first measurements of solar-like stellar winds. Results from these stellar wind studies and their implications for our understanding of the solar wind are reviewed here. Of particular interest are results concerning the past history of the solar wind and its impact on planetary atmospheres.

  19. Wind Statistics Offshore based on Satellite Images

    DEFF Research Database (Denmark)

    Hasager, Charlotte Bay; Mouche, Alexis; Badger, Merete

    2009-01-01

    Ocean wind maps from satellites are routinely processed both at Risø DTU and CLS based on the European Space Agency Envisat ASAR data. At Risø the a priori wind direction is taken from the atmospheric model NOGAPS (Navel Operational Global Atmospheric Prediction System) provided by the U.S. Navy......-based observations become available. At present preliminary results are obtained using the routine methods. The first step in the process is to retrieve raw SAR data, calibrate the images and use a priori wind direction as input to the geophysical model function. From this process the wind speed maps are produced....... The wind maps are geo-referenced. The second process is the analysis of a series of geo-referenced SAR-based wind maps. Previous research has shown that a relatively large number of images are needed for achieving certain accuracies on mean wind speed, Weibull A and k (scale and shape parameters...

  20. Computational modelling of an operational wind turbine and validation with LIDAR

    Science.gov (United States)

    Creech, Angus; Fruh, Wolf-Gerrit; Clive, Peter

    2010-05-01

    We present a computationally efficient method to model the interaction of wind turbines with the surrounding flow, where the interaction provides information on the power generation of the turbine and the generated wake behind the turbine. The turbine representation is based on the principle of an actuator volume, whereby the energy extraction and balancing forces on the fluids are formulated as body forces which avoids the extremely high computational costs of boundary conditions and forces. Depending on the turbine information available, those forces can be derived either from published turbine performance specifications or from their rotor and blade design. This turbine representation is then coupled to a Computational Fluid Dynamics package, in this case the hr-adaptive Finite-Element code Fluidity from Imperial College, London. Here we present a simulation of an operational 950kW NEG Micon NM54 wind turbine installed in the west of Scotland. The calculated wind is compared with LIDAR measurements using a Galion LIDAR from SgurrEnergy. The computational domain extends over an area of 6km by 6km and a height of 750m, centred on the turbine. The lower boundary includes the orography of the terrain and surface roughness values representing the vegetation - some forested areas and some grassland. The boundary conditions on the sides are relaxed Dirichlet conditions, relaxed to an observed prevailing wind speed and direction. Within instrumental errors and model limitations, the overall flow field in general and the wake behind the turbine in particular, show a very high degree of agreement, demonstrating the validity and value of this approach. The computational costs of this approach are such that it is possible to extend this single-turbine example to a full wind farm, as the number of required mesh nodes is given by the domain and then increases only linearly with the number of turbines

  1. Wind Conditions for Wind Farm Hanstholm

    DEFF Research Database (Denmark)

    Pena Diaz, Alfredo; Hahmann, Andrea N.; Mann, Jakob

    The net annual energy production (AEP) of the Hanstholm Wind Farm is 158 GWh per year for the Siemens SWT-3.6-120 turbine and 140 GWh for the Vestas V112-3.0 turbine. These values have an uncertainty (standard deviation) of 6%. This result is mainly based on the data for Risø DTU’s test station...... at Høvsøre where wind speeds are measured at approximately the same height as the turbines at Hanstholm and where the terrain is similar. On top of that meso-scale modeling has been used to extrapolate the climatology from Høvsøre to Hanstholm increasing the AEP by almost 6% compared to just using...... the Høvsøre climatology directly. This method of extrapolation is rather new, but several older investigations indicate that the wind resource at Hanstholm is slightly higher than at Høvsøre. The work is carried out for Grontmij-Carl Bro according to a contract dated January 18th 2011....

  2. Wind power

    International Nuclear Information System (INIS)

    2006-06-01

    This road-map proposes by the Group Total aims to inform the public on the wind power. It presents the principles, the technology takes off, its applications and technology focus, the global market trends and the outlooks and Total commitments in the domain. (A.L.B.)

  3. Wind energy

    International Nuclear Information System (INIS)

    Portilla S, L.A.

    1995-01-01

    The wind energy or eolic energy is a consequence of solar energy, the one which is absorbed by the atmosphere and is transformed into energy of movement of large bulks of air. In this process the atmosphere acts as the filter to the solar radiation and demotes the ultraviolet beams that result fatal to life in the Earth. The ionosphere is the most external cap and this is ionized by means of absorption process of ultraviolet radiation arising to the Sun. The atmosphere also acts as a trap to the infrared radiation, it that results from the continual process of energetic degradation. In this way, the interaction between Earth - Atmospheres, is behaved as a great greenhouse, maintaining the constant temperatures, including in the dark nights. Processes as the natural convection (that occur by the thermodynamic phenomenon), equatorial calmness, trade winds and against trade winds and global distribution of the air currents are described. The other hand, techniques as the transformation of the wind into energy and its parameters also are shown

  4. Wind Energy Japan

    Energy Technology Data Exchange (ETDEWEB)

    Komatsubara, Kazuyo [Embassy of the Kingdom of the Netherlands, Tokyo (Japan)

    2012-06-15

    An overview is given of wind energy in Japan: Background; Wind Energy in Japan; Japanese Wind Energy Industry; Government Supports; Useful Links; Major Japanese Companies; Profiles of Major Japanese Companies; Major Wind Energy Projects in Japan.

  5. Grid integration of wind energy

    CERN Document Server

    Heier, Siegfried

    2014-01-01

    This timely update provides detailed treatment of the integration of wind power into electrical power systems, including brand new material on offshore wind power farms and technologies This third English edition is based on new material from the fourth and fifth German editions (Windkraftanlagen: Systemauslegung, Netzintegration und Regelung, 5. Auflage, published by Teubner B.G. Gmbh, July 2009). It answers the question of how, with the proper control and direction, wind turbines can be made to operate more similarly to conventional power plants. The revised third edition addresses the engin

  6. Frequency and timing stability of an airborne injection-seeded Nd:YAG laser system for direct-detection wind lidar.

    Science.gov (United States)

    Lemmerz, Christian; Lux, Oliver; Reitebuch, Oliver; Witschas, Benjamin; Wührer, Christian

    2017-11-10

    We report on the design and performance of the laser deployed in the airborne demonstrator Doppler wind lidar for the Aeolus mission of the European Space Agency (ESA). The all-solid-state, diode-pumped and frequency-tripled Nd:YAG laser is realized as a master oscillator power amplifier (MOPA) system, generating 60 mJ of single-frequency pulses at 355 nm wavelength, 50 Hz repetition rate and 20 ns pulse duration. For the measurement of the Doppler frequency shift over several accumulated laser shots, the frequency stability of the laser is of crucial importance. Injection-seeding, in combination with an active cavity control based on the Ramp-Delay-Fire technique, provides a pulse-to-pulse frequency stability of 0.25 MHz measured at 1064 nm under laboratory conditions. This value increases to 0.31 MHz for airborne operation in a vibration environment that has been characterized by multiple acceleration sensors during different flight conditions. In addition, a pure Ramp-Fire setting was tested for comparison leading to a frequency stability of 0.16 MHz both in airborne operation and on ground. The laser cavity control electronics also have to provide a trigger signal for the lidar detection electronics, about 60 μs prior to the expected laser pulse emission and with high timing stability. An in-flight timing stability of below 100 ns was measured decreasing to 20 ns for a shorter pre-trigger time of 10 μs.

  7. Impact of active and break wind spells on the demand-supply balance in wind energy in India

    Science.gov (United States)

    Kulkarni, Sumeet; Deo, M. C.; Ghosh, Subimal

    2018-02-01

    With an installed capacity of over 19,000 MW, the wind power currently accounts for almost 70% of the total installed capacity among the renewable energy sector in India. The extraction of wind power mainly depends on prevailing meteorology which is strongly influenced by monsoon variability. The monsoon season is characterized by significant fluctuations in between periods of wet and dry spells. During the dry spells, the demand for power from agriculture and cooling equipment increases, whereas during the wet periods, such demand reduces, although, at the same time, the power supply increases because of strong westerly winds contributing to an enhanced production of wind energy. At this backdrop, we aim to assess the impact of intra-seasonal wind variability on the balance of energy supply and demand during monsoon seasons in India. Further, we explore the probable cause of wind variability by relating it to El Nino events. It is observed that the active and break phases in wind significantly impact the overall wind potential output. Although the dry spells are generally found to reduce the overall wind potential, their impact on the potential seems to have declined after the year 2000. The impact of meteorological changes on variations in wind power studied in this work should find applications typically in taking investment decisions on conventional generation facilities, like thermal, which are currently used to maintain the balance of power supply and demand.

  8. Lattice Wind Description and Characterization of Mexico City Local Wind Events in the 2001–2006 Period

    Directory of Open Access Journals (Sweden)

    Alejandro Salcido

    2015-07-01

    Full Text Available Urban transformation and expansion in Mexico City continuously affect its urban morphology, and therefore the modes of wind circulation inside it and their occurrence probabilities. Knowledge on these topics is an important issue for urban planning and for other urban studies, such as air quality assessment. In this paper, using a lattice wind model at a meso-β scale, we develop a simple description and characterization of Mexico City local wind events that occurred during the period 2001–2006, including an estimation of the occurrence probabilities. This region was modeled as a 2D lattice domain of identical cells, and wind conditions in each cell were described by four wind attributes: the horizontal velocity components, divergence, and vorticity. Models of one and four cells were applied to wind data furnished by the meteorological network of the city. Results include the following: Early morning: low intensity winds (75% from N, NW, W and SW (75%, convergent (93%, with a slight predominance of cyclonic vorticity (54%. Morning and early afternoon: winds from N, NE and E (72% with speeds from 0.5 to 3.5 m/s, slight prevailing of convergent winds (51%, and slight predominance of cyclonic vorticity (57%. Late afternoon and night: winds blowing from N, NW, and S (63% with speeds from 1.5 to 3.5 m/s (66%, convergent (90%, and cyclonic (72%.

  9. Gearless wind power generator

    Energy Technology Data Exchange (ETDEWEB)

    Soederlund, L.; Ridanpaeae, P.; Vihriaelae, H.; Peraelae, R. [Tampere Univ. of Technology (Finland). Lab. of Electricity and Magnetism

    1998-10-01

    In the project a 100 kW axial flux permanent magnet wind power generator has been designed. The toroidal stator with air gap winding is placed between two rotating discs with permanent magnets. The magnet material is NdBFe due to its excellent magnetic properties compared to other materials. This type of topology enables a very large number of poles compared to conventional machine of the same size. A large number of poles is required to achieve a low rotational speed and consequently a direct driven system. The stator winding is formed by rectangular coils. The end winding is very short leading to small resistive losses. On the other hand, the absence of iron teeth causes eddy current losses in the conductors. These can be restricted to an acceptable level by keeping the wire diameter and flux density small. This means that the number of phases should be large. Several independent three phase systems may be used. The toothless stator also means that the iron losses are small and there exists no cogging torque

  10. Wind Loads on Structures

    DEFF Research Database (Denmark)

    Dyrbye, Claes; Hansen, Svend Ole

    Wind loads have to be taken into account when designing civil engineering structures. The wind load on structures can be systematised by means of the wind load chain: wind climate (global), terrain (wind at low height), aerodynamic response (wind load to pressure), mechanical response (wind...... pressure to structural response) and design criteria. Starting with an introduction of the wind load chain, the book moves on to meteorological considerations, atmospheric boundary layer, static wind load, dynamic wind load and scaling laws used in wind-tunnel tests. The dynamic wind load covers vibrations...... induced by wind turbulence, vortex shedding, flutter and galloping. The book gives a comprehensive treatment of wind effects on structures and it will be useful for consulting engineers designing wind-sensitive structures. It will also be valuable for students of civil engineering as textbook...

  11. The Wind Energy Potential of Kurdistan, Iran.

    Science.gov (United States)

    Arefi, Farzad; Moshtagh, Jamal; Moradi, Mohammad

    2014-01-01

    In the current work by using statistical methods and available software, the wind energy assessment of prone regions for installation of wind turbines in, Qorveh, has been investigated. Information was obtained from weather stations of Baneh, Bijar, Zarina, Saqez, Sanandaj, Qorveh, and Marivan. The monthly average and maximum of wind speed were investigated between the years 2000-2010 and the related curves were drawn. The Golobad curve (direction and percentage of dominant wind and calm wind as monthly rate) between the years 1997-2000 was analyzed and drawn with plot software. The ten-minute speed (at 10, 30, and 60 m height) and direction (at 37.5 and 10 m height) wind data were collected from weather stations of Iranian new energy organization. The wind speed distribution during one year was evaluated by using Weibull probability density function (two-parametrical), and the Weibull curve histograms were drawn by MATLAB software. According to the average wind speed of stations and technical specifications of the types of turbines, the suitable wind turbine for the station was selected. Finally, the Divandareh and Qorveh sites with favorable potential were considered for installation of wind turbines and construction of wind farms.

  12. The Wind Energy Potential of Kurdistan, Iran

    Science.gov (United States)

    Arefi, Farzad; Moshtagh, Jamal; Moradi, Mohammad

    2014-01-01

    In the current work by using statistical methods and available software, the wind energy assessment of prone regions for installation of wind turbines in, Qorveh, has been investigated. Information was obtained from weather stations of Baneh, Bijar, Zarina, Saqez, Sanandaj, Qorveh, and Marivan. The monthly average and maximum of wind speed were investigated between the years 2000–2010 and the related curves were drawn. The Golobad curve (direction and percentage of dominant wind and calm wind as monthly rate) between the years 1997–2000 was analyzed and drawn with plot software. The ten-minute speed (at 10, 30, and 60 m height) and direction (at 37.5 and 10 m height) wind data were collected from weather stations of Iranian new energy organization. The wind speed distribution during one year was evaluated by using Weibull probability density function (two-parametrical), and the Weibull curve histograms were drawn by MATLAB software. According to the average wind speed of stations and technical specifications of the types of turbines, the suitable wind turbine for the station was selected. Finally, the Divandareh and Qorveh sites with favorable potential were considered for installation of wind turbines and construction of wind farms. PMID:27355042

  13. A Broad Continuum of Aeolian Impact Ripple Sizes on Mars is Allowed by Low Dynamic Wind Pressures

    Science.gov (United States)

    Sullivan, R. J., Jr.; Kok, J. F.; Yizhaq, H.

    2017-12-01

    Aeolian impact ripples are generated by impacts of wind-blown sand grains, and are common in environments with loose sand on Earth and Mars. Previous work has shown that, within a fully developed saltation cloud, impact ripple height grows upward into the boundary layer until limited by the effects of increasing wind dynamic pressure at the crest (e.g., lengthening of splash trajectories, or direct entrainment of grains by the wind). On Earth, this process limits ripples of well-sorted 250 µm dune sands to heights of millimeters, and strong winds can impose sufficient lateral dynamic pressure to flatten and erase these ripples. Rover observations show much larger ripple-like bedforms on Mars, raising questions about their formative mechanism. Here, we hypothesize that two factors allow impact ripples to grow much higher on Mars than on Earth: (1) previous work predicts a much larger difference between impact threshold and fluid threshold wind speeds on Mars than on Earth; and (2) recent analysis has revealed how low saltation flux can be initiated and sustained well below fluid threshold on Mars, allowing impact ripples to migrate entirely under prevailing conditions of relatively low wind speeds in the thin martian atmosphere. Under these circumstances, martian ripples would need to grow much larger than on Earth before reaching their maximum height limited by wind dynamic pressure effects. Because the initial size of impact ripples is similar on Mars and Earth, this should generate a much broader continuum of impact ripple sizes on Mars. Compared with Earth, far more time should be needed on Mars for impact ripples to achieve their maximum possible size. Consequently, in cases where wind azimuths are mixed but one azimuth is more dominant than others, martian impact ripples of all sizes can exist together in the same setting, with the largest examples reflecting the most common/formative wind azimuths. In cases where wind azimuth is not dominated by a single

  14. Winds at the Phoenix landing site

    DEFF Research Database (Denmark)

    Holstein-Rathlou, C.; Gunnlaugsson, H.P.; Merrison, J.P.

    2010-01-01

    Wind speeds and directions were measured on the Phoenix Lander by a mechanical anemometer, the so-called Telltale wind indicator. Analysis of images of the instrument taken with the onboard imager allowed for evaluation of wind speeds and directions. Daily characteristics of the wind data...... and frost formation are described and discussed. Two different mechanisms of dust lifting affecting the Phoenix site are proposed based on observations made with Mars Color Imager on Mars Reconnaissance Orbiter and the Telltale. The first is related to evaporation of the seasonal CO2 ice and is observed up...

  15. On the prevailing construction waste recycling practices: a South East Queensland study.

    Science.gov (United States)

    Tam, Vivian W Y; Kotrayothar, Duangthidar; Loo, Yew-Chaye

    2009-03-01

    Waste generated from construction and building demolition work constitutes about 68% of all solid waste generated each year in South East Queensland. Consequently, it has created a serious waste management problem. The State Governments of Victoria and New South Wales have been encouraging the use of recycled materials from construction and related waste; they have also promulgated specifications for their use. In Queensland, however, similar regulations are not anticipated in the near future, which explains the lack of funded research conducted in this important arena. This paper presents an evaluation of the prevailing waste recycling practices in Queensland. Nine sites were visited, including two construction sites, three demolition sites, three recycling plants and one landfill in South East Queensland. The difficulties encountered by the recycling programme operators and their associates at these sites are described and the benefits of recycling construction materials are presented. One of the major barriers is that the local councils disallow the use of recycled materials in new construction work. To help rectify these impediments to recycling, recommendations are given to increase the use of recycled construction waste in South East Queensland.

  16. Prevailing practices in airway management: a prospective single-centre observational study of endotracheal intubation.

    Science.gov (United States)

    Cheong, Geraldine Pei Chin; Kannan, Anusha; Koh, Kwong Fah; Venkatesan, Kumaresh; Seet, Edwin

    2018-03-01

    Airway management during anaesthesia has potential difficulties and risks. We aimed to investigate the utility of routine airway assessment for predicting difficult tracheal intubation, review the prevailing practice of videolaryngoscope use amongst anaesthetists in a teaching hospital and determine the incidence of intraoperative and postoperative airway-related complications. A prospective observational study of 1,654 patients undergoing general anaesthesia with endotracheal intubation over a seven-month period was performed. Data regarding airway and anaesthetic management was collected and analysed. Videolaryngoscopes were used as the first-choice equipment in 60.5% of the cohort. The incidence of difficult intubation was 2.1%, of which 45.7% of cases were unanticipated. The sensitivity of airway assessment was 54.3%, with a positive predictive value of 8.1%. When difficult intubation was anticipated, more videolaryngoscopes were used as the first equipment of choice compared to the Macintosh laryngoscope (p < 0.001). In the Macintosh group, more patients required a change of airway equipment (p = 0.015), but the number of intubation attempts was similar (p = 0.293). The incidence of intraoperative (p = 0.920) and postoperative complications (p = 0.380) were similar in both groups. Using the current predictors of difficult intubation, half of the difficult airways we encountered were unanticipated. Videolaryngoscopes were preferred when difficulty was anticipated and were also used in routine tracheal intubation. Copyright: © Singapore Medical Association.

  17. Appreciation of the nature of light demands enhancement over the prevailing scientific epistemology

    Science.gov (United States)

    Roychoudhuri, Chandrasekhar

    2011-09-01

    Based on attempts to resolve the problem of various self contradictory assumptions behind the prevailing belief on single photon interference, we have analyzed the process steps behind our experimental measurements and named the process as the Interaction Process Mapping Epistemology (IPM-E). This has helped us recognize that the quantum mechanical Measurement Problem has a much universal and deeper root in nature. Our scientific theorization process suffers from a Perpetual Information Challenge (PIC), which cannot be overcome by elegant and/or sophisticated mathematical theories alone. Iterative imaginative application of IPM-E needs to be used as a metaphorical analytical continuation to fill up the missing information gaps. IPM-E has also guided us to recognize the generic NIW-principle (Non-Interaction of Waves) in the linear domain, not explicitly recognized in current books and literature. Superposition effects become manifest through light-matter interactions. Detecting dipoles gets stimulated by multiple superposed beams; it sums the simultaneous multiple stimulations into a single resultant undulation, which then guides the resultant energy exchange. The consequent transformation in the detector corresponds to observed fringes. They neither represent interference of light; nor represent selective arrival or non-arrival of photons on the detector. Photons do not possess any force of mutual interaction to generate their redistribution. Implementation of IPM-E requires us to recognize our subjective interpretation propensity with which we are burdened due to our evolutionary successes.

  18. Why nature prevails over nurture in the making of the elite athlete.

    Science.gov (United States)

    Georgiades, Evelina; Klissouras, Vassilis; Baulch, Jamie; Wang, Guan; Pitsiladis, Yannis

    2017-11-14

    While the influence of nature (genes) and nurture (environment) on elite sporting performance remains difficult to precisely determine, the dismissal of either as a contributing factor to performance is unwarranted. It is accepted that a complex interaction of a combination of innumerable factors may mold a talented athlete into a champion. The prevailing view today is that understanding elite human performance will require the deciphering of two major sources of individual differences, genes and the environment. It is widely accepted that superior performers are endowed with a high genetic potential actualised through hard and prodigious effort. Heritability studies using the twin model have provided the basis to disentangle genetic and environmental factors that contribute to complex human traits and have paved the way to the detection of specific genes for elite sport performance. Yet, the heritability for most phenotypes essential to elite human performance is above 50% but below 100%, meaning that the environment is also important. Furthermore, individual differences can potentially also be explained not only by the impact of DNA sequence variation on biology and behaviour, but also by the effects of epigenetic changes which affect phenotype by modifying gene expression. Despite this complexity, the overwhelming and accumulating evidence, amounted through experimental research spanning almost two centuries, tips the balance in favour of nature in the "nature" and "nurture" debate. In other words, truly elite-level athletes are built - but only from those born with innate ability.

  19. Phylogenomics resolves a spider backbone phylogeny and rejects a prevailing paradigm for orb web evolution.

    Science.gov (United States)

    Bond, Jason E; Garrison, Nicole L; Hamilton, Chris A; Godwin, Rebecca L; Hedin, Marshal; Agnarsson, Ingi

    2014-08-04

    Spiders represent an ancient predatory lineage known for their extraordinary biomaterials, including venoms and silks. These adaptations make spiders key arthropod predators in most terrestrial ecosystems. Despite ecological, biomedical, and biomaterial importance, relationships among major spider lineages remain unresolved or poorly supported. Current working hypotheses for a spider "backbone" phylogeny are largely based on morphological evidence, as most molecular markers currently employed are generally inadequate for resolving deeper-level relationships. We present here a phylogenomic analysis of spiders including taxa representing all major spider lineages. Our robust phylogenetic hypothesis recovers some fundamental and uncontroversial spider clades, but rejects the prevailing paradigm of a monophyletic Orbiculariae, the most diverse lineage, containing orb-weaving spiders. Based on our results, the orb web either evolved much earlier than previously hypothesized and is ancestral for a majority of spiders or else it has multiple independent origins, as hypothesized by precladistic authors. Cribellate deinopoid orb weavers that use mechanically adhesive silk are more closely related to a diverse clade of mostly webless spiders than to the araneoid orb-weaving spiders that use adhesive droplet silks. The fundamental shift in our understanding of spider phylogeny proposed here has broad implications for interpreting the evolution of spiders, their remarkable biomaterials, and a key extended phenotype--the spider web. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Stellar winds

    International Nuclear Information System (INIS)

    Weymann, R.J.

    1978-01-01

    It is known that a steady outflow of material at comparable rates of mass loss but vastly different speeds is now known to be ubiquitous phenomenon among both the luminous hot stars and the luminous but cool red giants. The flows are probably massive enough in both cases to give rise to significant effects on stellar evolution and the mass balance between stars and the interstellar medium. The possible mechanisms for these phenomena as well as the methods of observation used are described. In particular, the mass-loss processes in stars other than the sun that also involve a steady flow of matter are considered. The evidence for their existence is described, and then the question of whether the process thought to produce the solar wind is also responsible for producing these stellar winds is explored

  1. 2016 Fee Wind energy directory

    International Nuclear Information System (INIS)

    2015-12-01

    France is currently engaged in the energy transition where ambitious goals are at stake to allow the country to be one of the leading European countries in renewable energies. The cost of onshore wind is getting more and more competitive and for this reason, wind energy professionals are committed in contributing actively to reach the 32 % objective of renewable energies in the final energy consumption and 40 % of renewable energies in the electricity mix for 2030. 2014 was marked by a swift growth of the installed onshore wind energy, the positive trend is confirmed in 2015 with more than 500 MW connected to the grid in the first half of the year, corresponding to the annual forecast of 1,200 MW for 2015. Thanks to the energy transition law, operational policies will be implemented through the multi-annual energy programming (PPE- programmation pluriannuelle de l'energie). France will therefore continue increasing its development of renewable energies. This law will also allow France to develop offshore wind energy and to strengthen its position regarding wind energy: with an objective of 15 GW of fixed offshore wind energy and 6 GW of floating wind energy to be built in the 2030 horizon, the sector will be able to guarantee its development, especially in the current context of strong worldwide competition. Some 10,000 direct and indirect jobs are awaited for offshore wind energy on the national territory and wind energy professionals underline that the development of the offshore wind sector will contribute to the economic dynamism of the country. This sector is thus a job creating sector as confirmed in the figures of the wind employment monitor (observatoire de l'emploi) in France, recording a significant growth in 2013 with 10,800 jobs. This upward trend was confirmed in 2014. This proves the continuous commitment of the wind industry in seeing the success of the energy transition in France in a context marked by numerous energy and climate events

  2. Health impact of wind farms.

    Science.gov (United States)

    Kurpas, Donata; Mroczek, Bozena; Karakiewicz, Beata; Kassolik, Krzysztof; Andrzejewski, Waldemar

    2013-01-01

    Wind power is employed worldwide as an alternative source of energy. At the same time, however, the health effects of wind turbines have become a matter of discussion. The purpose of this study is a critical review of available reports providing arguments both for and against the construction of wind farms. The authors also attempt to propose recommendations in accordance with the Evidence-Based Medicine (EBM) guidelines. In the case of exposure to wind farms, a randomized controlled trial (RCT) is impossible. To obtain the highest-level recommendations, analysis of case-control studies or cohort studies with control groups should be performed. Preferably, it should include geostatistical analysis conducted with the use of variograms and the kriging technique. Combinations of key words were entered into the Thomson Reuters Web of Knowledge (SM) and the Internet search engine Google. SHORT DESCRIPTION OF STATE OF THE ART: The nuisance caused by wind turbines is stereotypically linked with the noise that they produce. Nevertheless, the visual aspect of wind farms, opinions about them, and sensitivity to sound seem to be of the greater importance. To date, the direct correlations between the vicinity of modern wind farms, the noise that wind turbines make, and possible consequences to health have not been described in peer reviewed articles. Health effects are more probably associated with some environmental factors leading to annoyance or frustration. All types of studies share the same conclusion: wind turbines can provoke annoyance. As with any project involving changes in the local environment, a certain level of irritation among the population can be expected. There are elected officials and government representatives who should decide what level of social annoyance is acceptable, and whether wind power advantages outweigh its potential drawbacks. The influence of wind turbines on human emotional and physical health is a relatively new field of research. Further

  3. Wind Atlas Analysis and Application Program: WAsP 11 Help Facility

    DEFF Research Database (Denmark)

    2014-01-01

    The Wind Atlas Analysis and Application Program (WAsP) is a PC-program for horizontal and vertical extrapolation of wind climates. The program contains a complete set of models to calculate the effects on the wind of sheltering obstacles, surface roughness changes and terrain height variations....... The analysis part consists of a transformation of an observed wind climate (wind speed and direction distributions) to a generalised wind climate (wind atlas data set). The generalised wind climate can subsequently be applied for estimation of the wind climate and wind power potential, as well as for siting...

  4. Management of moderate wind energy coastal resources

    International Nuclear Information System (INIS)

    Karamanis, D.

    2011-01-01

    Research highlights: → Life cycle analysis reveals the viability of moderate wind fields utilization. → Wind turbine is the greenest electricity generator at a touristic site. → Wind parks should be collective applications of small hotel-apartments owners. -- Abstract: The feasibility of wind energy utilization at moderate wind fields was investigated for a typical touristic coastal site in Western Greece. Initially, the wind speed and direction as well as its availability, duration and diurnal variation were assessed. For an analysis period of eight years, the mean wind speed at ten meters was determined as 3.8 m s -1 with a small variation in monthly average wind speeds between 3.0 (January) and 4.4 m s -1 (October). The mean wind power density was less than 200 W m -2 at 10 m indicating the limiting suitability of the site for the usual renewable energy applications. However, life cycle analysis for wind turbine generators with lower cut-in, cut-out, and rated speeds revealed that the energy yield ratio can reach a value of six for a service life of 20 years while the energy pay-back period can be 3 years with 33 kt CO 2 -e of avoided greenhouse emissions. Therefore, the recent technological turbine improvements make wind power viable even at moderate wind fields. Moreover, the study of electricity supply of typical small hotel-apartments in the region of Western Greece indicated that the installation of 300 wind turbine generators in these moderate wind fields would cover the total consumption during the open touristic period with profits during the rest of the year. According to these results, wind turbine generators are the 'greenest' way of generating electricity in touristic coastal sites, even of moderate wind speeds.

  5. Wind conditions for wind turbine design

    Energy Technology Data Exchange (ETDEWEB)

    Maribo Pedersen, B.

    1999-04-01

    Delegates from Europe and USA attended the meeting and discussed general aspects of wind conditions for wind turbine design. The subjects and the presented papers covered a very broad range of aspects of wind conditions and related influence on the wind turbine. (EHS)

  6. NFLUX PRE: Validation of New Specific Humidity, Surface Air Temperature, and Wind Speed Algorithms for Ascending/Descending Directions and Clear or Cloudy Conditions

    Science.gov (United States)

    2015-06-18

    SDR ) satellite data, Environmental Data Record (EDR) readers, and direct observations (X) from buoys and ships to provide ocean surface state...are noted. Platform / Sensor QA U10 TA LTAN DMSP F16 / SSMIS SDR SDR SDR 17:22 DMSP F17 / SSMIS SDR SDR SDR 17:49 DMSP F18 / SSMIS SDR ... SDR SDR 17:06 POES N15 / AMSU SDR SDR 16:51 POES N18 / AMSU SDR SDR 15:23 POES N19 / AMSU SDR SDR

  7. Infrasound emission generated by wind turbines

    Science.gov (United States)

    Ceranna, Lars; Pilger, Christoph

    2014-05-01

    Aerodynamic noise emissions from the continuously growing number of wind turbines in Germany are creating increasing problems for infrasound recording systems. Such systems are equipped with highly sensitive micro pressure sensors, which are accurately measuring acoustic signals in a frequency range inaudible to humans. At infrasound station IGADE, north of Bremen, a constantly increasing background noise has been observed throughout the years since its installation in 2005. The spectral peaks are reflecting well the blade passing harmonics, which vary with prevailing wind speeds. Overall, a decrease is noted for the infrasound array's detection capability. This aspect is particularly important for the other two sites of the German infrasound stations I26DE in the Bavarian Forest and I27DE in Antarctica, because plans for installing wind turbines near these locations are being under discussion. These stations are part of the International Monitoring System (IMS) verifying compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT), and have to meet stringent specifications with respect to infrasonic background noise. Therefore data obtained during a field experiment with mobile micro-barometer stations for measuring the infrasonic pressure level of a single horizontal-axis wind turbine have been revisited. The results of this experiment successfully validate a theoretical model which estimates the generated sound pressure level of wind turbines and makes it possible to specify the minimum allowable distance between wind turbines and infrasound stations for undisturbed recording. Since the theoretical model also takes wind turbine design parameters into account, suitable locations for planned infrasound stations outside the determined disturbance range can be found, which will be presented; and vice versa, the model calculations' results for fixing the minimum distance for wind turbines planned for installation in the vicinity of an existing infrasound array.

  8. Doppler Wind Lidar Measurements and Scalability to Space

    Data.gov (United States)

    National Aeronautics and Space Administration — Global measurements of wind speed and direction from Doppler wind lidars, if available, would significantly improve forecasting of severe weather events such as...

  9. Validation of Sodar Measurements for Wind Power

    DEFF Research Database (Denmark)

    Hansen, Kurt Schaldemose

    2006-01-01

    A ground-based SODAR has been tested for 1½ years together with a traditional measurement set-up consisting of cups and vanes for measuring wind data for wind power assessment at a remote location. Many problems associated to the operation of a remote located SODAR have been solved during...... the project and a new remote power system has been designed. A direct comparison between SODAR and cup measurements revealed a limitation for the SODAR measurements during different weather conditions, especially since the SODAR was not able to measure wind speeds above 15 m/s due to an increasing back......-ground noise. Instead, using the SODAR as a profiler to establish representative wind speed profiles was successful. These wind speed profiles are combined with low height reference measurements to establish reliable hub height wind speed distributions. Representative wind speed profiles can be establish...

  10. Aerodynamic Analysis of a Vertical Axis Wind Turbine in a Diffuser

    NARCIS (Netherlands)

    Geurts, B.M.; Simao Ferreira, C.; Van Bussel, G.J.W.

    Wind energy in the urban environment faces complex and often unfavorable wind conditions. High turbulence, lower average wind velocities and rapid changes in the wind direction are common phenomena in the complex built environments. A possible way to improve the cost-efficiency of urban wind

  11. Wind Technologies & Evolving Opportunities (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Robichaud, R.

    2014-07-01

    This presentation covers opportunities for wind technology; wind energy market trends; an overview of the National Wind Technology Center near Boulder, Colorado; wind energy price and cost trends; wind turbine technology improvements; and wind resource characterization improvements.

  12. Investigation of wind characteristics and wind energy assessment in Sao Joao do Cariri (SJC) - Paraiba, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Lima, Laerte; Filho, Celso

    2010-09-15

    In this study wind characterization and wind energy assessment of the Sao Joao do Cariri (SJC) in Paraiba state situated in Brazilian northeast. The average wind speed and temperature for 25 and 50 m were found 4,74m/s, 24,46C and 5,31m/s 24,25C with wind speed predominate direction of SSE (165 degrees). Weibull shape, scale ,Weibull fit wind speed and Power wind density found 2,54, 5,4m/s, 4,76m/s and 103W/m2 for 25m wind height measurements and 2,59, 6,0m/s, 5,36m/s and 145W/m2 for 50m wind height measurements.

  13. Database on wind characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Hojstrup, J. [Riso National Lab., Roskilde (Denmark); Hansen, K.S. [Fluid Mechanics Section, Lyngby (Denmark)

    1996-12-31

    Wind data with high temporal resolution exist from a variety of sites, and is in demand by windturbine designers and wind engineers. Unfortunately it has always been a problem to gain access to a suitable amount of this data, because they are available from many different sources in different formats and with very different levels of documentation and quality control. We are now in the process of gaining access to a large amount of this type of data, checking the quality of the data and putting the data at the disposition of the windturbine designer community through easy Internet access. Online search will use summary statistics calculated for each series to help in the selection of data. The selected data can then be downloaded directly to the user. 3 figs.

  14. Optimization of monopiles for offshore wind turbines.

    Science.gov (United States)

    Kallehave, Dan; Byrne, Byron W; LeBlanc Thilsted, Christian; Mikkelsen, Kristian Kousgaard

    2015-02-28

    The offshore wind industry currently relies on subsidy schemes to be competitive with fossil-fuel-based energy sources. For the wind industry to survive, it is vital that costs are significantly reduced for future projects. This can be partly achieved by introducing new technologies and partly through optimization of existing technologies and design methods. One of the areas where costs can be reduced is in the support structure, where better designs, cheaper fabrication and quicker installation might all be possible. The prevailing support structure design is the monopile structure, where the simple design is well suited to mass-fabrication, and the installation approach, based on conventional impact driving, is relatively low-risk and robust for most soil conditions. The range of application of the monopile for future wind farms can be extended by using more accurate engineering design methods, specifically tailored to offshore wind industry design. This paper describes how state-of-the-art optimization approaches are applied to the design of current wind farms and monopile support structures and identifies the main drivers where more accurate engineering methods could impact on a next generation of highly optimized monopiles. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  15. The networked minority: How a small group prevailed in a local windfarm conflict

    International Nuclear Information System (INIS)

    Anderson, Carmel

    2013-01-01

    This paper aims to explain through a qualitative case study how a small protest group prevailed during a local windfarm conflict in south-eastern Australia. A social capital analytical framework was developed to analyse the data. The analysis found that two communities inhabited the area for which the windfarm development was proposed. The public participation process failed to address the concerns of both communities and led to the emergence of a social network of resistance. The network had high stocks of bridging social capital, which enabled an effective protest that led to the abandonment of the development. Their effectiveness was inadvertently aided by the windfarm supporters who were unable to act collectively to defend their interests because socio-economic changes in the community among other factors had led to a depletion of their social capital. In this context, different democratic participatory processes were needed to address the concerns of the two communities. Guidance and tools for researching and developing the types of participatory processes needed for vulnerable communities with low social capital and those similar to the social network with high social capital are provided. These will inform community-appropriate public participation processes and participatory planning policy. - Highlights: ► A case study of a local social network's resistance to a windfarm is undertaken. ► The link between high social capital and resistance is confirmed. ► Successful protest groups can be aided by passive windfarm supporters. ► Protesters are likely to participate in well-designed participatory processes. ► Guidance for developing community-specific participatory processes is provided

  16. Surface tension prevails over solute effect in organic-influenced cloud droplet activation

    Science.gov (United States)

    Ovadnevaite, Jurgita; Zuend, Andreas; Laaksonen, Ari; Sanchez, Kevin J.; Roberts, Greg; Ceburnis, Darius; Decesari, Stefano; Rinaldi, Matteo; Hodas, Natasha; Facchini, Maria Cristina; Seinfeld, John H.; O' Dowd, Colin

    2017-06-01

    The spontaneous growth of cloud condensation nuclei (CCN) into cloud droplets under supersaturated water vapour conditions is described by classic Köhler theory. This spontaneous activation of CCN depends on the interplay between the Raoult effect, whereby activation potential increases with decreasing water activity or increasing solute concentration, and the Kelvin effect, whereby activation potential decreases with decreasing droplet size or increases with decreasing surface tension, which is sensitive to surfactants. Surface tension lowering caused by organic surfactants, which diminishes the Kelvin effect, is expected to be negated by a concomitant reduction in the Raoult effect, driven by the displacement of surfactant molecules from the droplet bulk to the droplet-vapour interface. Here we present observational and theoretical evidence illustrating that, in ambient air, surface tension lowering can prevail over the reduction in the Raoult effect, leading to substantial increases in cloud droplet concentrations. We suggest that consideration of liquid-liquid phase separation, leading to complete or partial engulfing of a hygroscopic particle core by a hydrophobic organic-rich phase, can explain the lack of concomitant reduction of the Raoult effect, while maintaining substantial lowering of surface tension, even for partial surface coverage. Apart from the importance of particle size and composition in droplet activation, we show by observation and modelling that incorporation of phase-separation effects into activation thermodynamics can lead to a CCN number concentration that is up to ten times what is predicted by climate models, changing the properties of clouds. An adequate representation of the CCN activation process is essential to the prediction of clouds in climate models, and given the effect of clouds on the Earth’s energy balance, improved prediction of aerosol-cloud-climate interactions is likely to result in improved assessments of future

  17. Surface tension prevails over solute effect in organic-influenced cloud droplet activation.

    Science.gov (United States)

    Ovadnevaite, Jurgita; Zuend, Andreas; Laaksonen, Ari; Sanchez, Kevin J; Roberts, Greg; Ceburnis, Darius; Decesari, Stefano; Rinaldi, Matteo; Hodas, Natasha; Facchini, Maria Cristina; Seinfeld, John H; O' Dowd, Colin

    2017-06-29

    The spontaneous growth of cloud condensation nuclei (CCN) into cloud droplets under supersaturated water vapour conditions is described by classic Köhler theory. This spontaneous activation of CCN depends on the interplay between the Raoult effect, whereby activation potential increases with decreasing water activity or increasing solute concentration, and the Kelvin effect, whereby activation potential decreases with decreasing droplet size or increases with decreasing surface tension, which is sensitive to surfactants. Surface tension lowering caused by organic surfactants, which diminishes the Kelvin effect, is expected to be negated by a concomitant reduction in the Raoult effect, driven by the displacement of surfactant molecules from the droplet bulk to the droplet-vapour interface. Here we present observational and theoretical evidence illustrating that, in ambient air, surface tension lowering can prevail over the reduction in the Raoult effect, leading to substantial increases in cloud droplet concentrations. We suggest that consideration of liquid-liquid phase separation, leading to complete or partial engulfing of a hygroscopic particle core by a hydrophobic organic-rich phase, can explain the lack of concomitant reduction of the Raoult effect, while maintaining substantial lowering of surface tension, even for partial surface coverage. Apart from the importance of particle size and composition in droplet activation, we show by observation and modelling that incorporation of phase-separation effects into activation thermodynamics can lead to a CCN number concentration that is up to ten times what is predicted by climate models, changing the properties of clouds. An adequate representation of the CCN activation process is essential to the prediction of clouds in climate models, and given the effect of clouds on the Earth's energy balance, improved prediction of aerosol-cloud-climate interactions is likely to result in improved assessments of future

  18. Prevailing negative soil biota effect and no evidence for local adaptation in a widespread Eurasian grass.

    Directory of Open Access Journals (Sweden)

    Viktoria Wagner

    2011-03-01

    Full Text Available Soil biota effects are increasingly accepted as an important driver of the abundance and distribution of plants. While biogeographical studies on alien invasive plant species have indicated coevolution with soil biota in their native distribution range, it is unknown whether adaptation to soil biota varies among populations within the native distribution range. The question of local adaptation between plants and their soil biota has important implications for conservation of biodiversity and may justify the use of seed material from local provenances in restoration campaigns.We studied soil biota effects in ten populations of the steppe grass Stipa capillata from two distinct regions, Europe and Asia. We tested for local adaptation at two different scales, both within (ca. 10-80 km and between (ca. 3300 km regions, using a reciprocal inoculation experiment in the greenhouse for nine months. Generally, negative soil biota effects were consistent. However, we did not find evidence for local adaptation: both within and between regions, growth of plants in their 'home soil' was not significantly larger relative to that in soil from other, more distant, populations.Our study suggests that negative soil biota effects can prevail in different parts of a plant species' range. Absence of local adaptation points to the possibility of similar rhizosphere biota composition across populations and regions, sufficient gene flow to prevent coevolution, selection in favor of plasticity, or functional redundancy among different soil biota. From the point of view of plant--soil biota interactions, our findings indicate that the current practice of using seeds exclusively from local provenances in ecosystem restoration campaigns may not be justified.

  19. Wind Power Meteorology

    DEFF Research Database (Denmark)

    Lundtang Petersen, Erik; Mortensen, Niels Gylling; Landberg, Lars

    Wind power meteorology has evolved as an applied science, firmly founded on boundary-layer meteorology, but with strong links to climatology and geography. It concerns itself with three main areas: siting of wind turbines, regional wind resource assessment, and short-term prediction of the wind...... resource. The history, status and perspectives of wind power meteorology are presented, with emphasis on physical considerations and on its practical application. Following a global view of the wind resource, the elements of boundary layer meteorology which are most important for wind energy are reviewed......: wind profiles and shear, turbulence and gust, and extreme winds. The data used in wind power meteorology stem mainly from three sources: onsite wind measurements, the synoptic networks, and the re-analysis projects. Wind climate analysis, wind resource estimation and siting further require a detailed...

  20. The dune effect on sand-transporting winds on Mars

    Science.gov (United States)

    Jackson, Derek W. T.; Bourke, Mary C.; Smyth, Thomas A. G.

    2015-11-01

    Wind on Mars is a significant agent of contemporary surface change, yet the absence of in situ meteorological data hampers the understanding of surface-atmospheric interactions. Airflow models at length scales relevant to landform size now enable examination of conditions that might activate even small-scale bedforms (ripples) under certain contemporary wind regimes. Ripples have the potential to be used as modern `wind vanes' on Mars. Here we use 3D airflow modelling to demonstrate that local dune topography exerts a strong influence on wind speed and direction and that ripple movement likely reflects steered wind direction for certain dune ridge shapes. The poor correlation of dune orientation with effective sand-transporting winds suggests that large dunes may not be mobile under modelled wind scenarios. This work highlights the need to first model winds at high resolution before inferring regional wind patterns from ripple movement or dune orientations on the surface of Mars today.

  1. Assessment of the emission of PCDD/Fs and dioxin-like PCBs from an industrial area over a nearby town using a selective wind direction sampling device

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Karell; Austrui, Joan Rivera [Lab. of Dioxins, Mass Spectrometry Laboratory, Environmental Chemistry Department, IDAEA-CSIC, Jordi Girona 18, 08034 Barcelona (Spain); Jover, Eric [FEMAN group, IN2UB, Applied Physics and Optics Department, Physics Faculty, University of Barcelona, Marti i Franques 1, 08028 Barcelona (Spain); Abalos, Manuela; Rivera, Josep [Lab. of Dioxins, Mass Spectrometry Laboratory, Environmental Chemistry Department, IDAEA-CSIC, Jordi Girona 18, 08034 Barcelona (Spain); Abad, Esteban, E-mail: esteban.abad@idaea.csic.e [Lab. of Dioxins, Mass Spectrometry Laboratory, Environmental Chemistry Department, IDAEA-CSIC, Jordi Girona 18, 08034 Barcelona (Spain)

    2010-03-15

    The development of new sampling devices or strategies to assess the concentration of persistent organic pollutants (POPs) in the environment has increased in the last two decades. In this study, a selective sampling device was used to evaluate the impact of potential local sources of polychlorinated dibenzo-p-dioxin and dibenzofuran (PCDD/Fs) and dioxin-like polychlorinated biphenyl (dl-PCBs) emissions on the ambient air levels of such compounds in a town near an important industrial estate. Average concentrations of target compounds of up to 2.5 times for PCDD/Fs and 2 times for dl-PCBs were found to come from the industrial state confirming this area as the main responsible for the majority of such compounds reaching the town. This finding was supported by a PCDD/F and dl-PCB sample profile analysis and a principal component analysis (PCA), which established a direct link between the dioxin-like compounds found in the samples collected in the town and their source. - Selective ambient air samplers provide a valuable information on POP emission sources

  2. Prospecting for Wind

    Science.gov (United States)

    Swapp, Andy; Schreuders, Paul; Reeve, Edward

    2011-01-01

    Many people use wind to help meet their needs. Over the years, people have been able to harness or capture the wind in many different ways. More recently, people have seen the rebirth of electricity-generating wind turbines. Thus, the age-old argument about technology being either good or bad can also be applied to the wind. The wind can be a…

  3. Careers in Wind Energy

    Science.gov (United States)

    Liming, Drew; Hamilton, James

    2011-01-01

    As a common form of renewable energy, wind power is generating more than just electricity. It is increasingly generating jobs for workers in many different occupations. Many workers are employed on wind farms: areas where groups of wind turbines produce electricity from wind power. Wind farms are frequently located in the midwestern, western, and…

  4. Feasibility of small wind turbines in Ontario: Integrating power curves with wind trends

    OpenAIRE

    Ashtine, Masaō; Bello, Richard; Higuchi, Kaz

    2016-01-01

    Micro-scale/small wind turbines, unlike larger utility-scale turbines, produce electricity at a rate of 300 W to 10 kW at their rated wind speed and are typically below 30 m in hub-height. These wind turbines have much more flexibility in their costs, maintenance and siting owing to their size and can provided wind energy in areas much less suited for direct supply to the grid system. The small wind industry has been substantially slow to progress in Ontario, Canada, and there is much debate ...

  5. 7 CFR 1427.25 - Determination of the prevailing world market price and the adjusted world price for upland cotton.

    Science.gov (United States)

    2010-01-01

    ... and the adjusted world price for upland cotton. 1427.25 Section 1427.25 Agriculture Regulations of the..., PURCHASES, AND OTHER OPERATIONS COTTON Nonrecourse Cotton Loan and Loan Deficiency Payments § 1427.25 Determination of the prevailing world market price and the adjusted world price for upland cotton. (a) CCC will...

  6. Prevailing climatic trends and runoff response from Hindukush–Karakoram–Himalaya, upper Indus Basin

    Directory of Open Access Journals (Sweden)

    S. U. Hasson

    2017-05-01

    Full Text Available Largely depending on the meltwater from the Hindukush–Karakoram–Himalaya, withdrawals from the upper Indus Basin (UIB contribute half of the surface water availability in Pakistan, indispensable for agricultural production systems, industrial and domestic use, and hydropower generation. Despite such importance, a comprehensive assessment of prevailing state of relevant climatic variables determining the water availability is largely missing. Against this background, this study assesses the trends in maximum, minimum and mean temperatures, diurnal temperature range and precipitation from 18 stations (1250–4500 m a.s.l. for their overlapping period of record (1995–2012 and, separately, from six stations of their long-term record (1961–2012. For this, a Mann–Kendall test on serially independent time series is applied to detect the existence of a trend, while its true slope is estimated using the Sen's slope method. Further, locally identified climatic trends are statistically assessed for their spatial-scale significance within 10 identified subregions of the UIB, and the spatially (field- significant climatic trends are then qualitatively compared with the trends in discharge out of corresponding subregions. Over the recent period (1995–2012, we find warming and drying of spring (field-significant in March and increasing early melt season discharge from most of the subregions, likely due to a rapid snowmelt. In stark contrast, most of the subregions feature a field-significant cooling within the monsoon period (particularly in July and September, which coincides well with the main glacier melt season. Hence, a decreasing or weakly increasing discharge is observed from the corresponding subregions during mid- to late melt season (particularly in July. Such tendencies, being largely consistent with the long-term trends (1961–2012, most likely indicate dominance of the nival but suppression of the glacial melt regime

  7. Efeitos da velocidade e da direção do vento na uniformidade de aplicação de água de sistemas autopropelidos Effects of wind speed and direction on water application uniformity of traveler irrigation systems

    Directory of Open Access Journals (Sweden)

    Henrique F. E. de Oliveira

    2012-08-01

    Full Text Available A velocidade e a direção de incidência do vento, em relação ao eixo de deslocamento do aspersor, são variáveis apresentadas em vários trabalhos como fatores importantes para a determinação da uniformidade de aplicação de água dos equipamentos autopropelidos de irrigação. No entanto, em razão das dificuldades de se conduzir estudos de campo com canhões hidráulicos sob condições controladas de direção e velocidade do vento, as recomendações de espaçamento entre carreadores, em sua maioria, consideram apenas o efeito da velocidade do vento, sem mencionar a direção de sua incidência. Neste trabalho, a aplicação de coeficientes semiempíricos do modelo Richards & Weatherhead, ajustados com base em ensaios de campo do canhão PLONA RL-250, possibilitou realizar, por meio de simulações digitais, uma análise quantitativa dos efeitos da velocidade e da direção do vento sobre a uniformidade de aplicação de água dos sistemas autopropelidos. As simulações indicaram que, na medida em que a incidência do vento passa de perpendicular para paralela ao eixo de deslocamento, os efeitos prejudiciais da velocidade do vento sobre a uniformidade são ampliados. Desta forma, fica evidenciado que tanto a direção como a velocidade do vento devem ser consideradas nas recomendações de espaçamento entre carreadores.Wind velocity and its direction, in relation to the sprinkler travel axis, are pointed out as key factors in determining water application uniformity of traveler irrigation machines. However, due to difficulties in running field tests with rain guns under controlled wind conditions, most towpath spacing recommendations consider only wind velocity without mentioning its direction. In this study, the application of semi-empirical parameters from RICHARDS & WEATERHEAD model's, adjusted based on field tests with the rain gun PLONA RL-250, provided with the help of computer simulation, the data necessary for a

  8. Field test of a lidar wind profiler

    NARCIS (Netherlands)

    Kunz, G.J.

    1996-01-01

    Wind speeds and wind directions are measured remotely using an incoherent backscatter lidar system operating at a wavelength of 1.06 mm with a maximum repetition rate of 13 Hz. The principle of the measurements is based on following detectable atmospheric structures, which are transported by the

  9. Modelling the wind climate of Ireland

    DEFF Research Database (Denmark)

    Frank, H.P.; Landberg, L.

    1997-01-01

    The wind climate of Ireland has been calculated using the Karlsruhe Atmospheric Mesoscale Model KAMM. The climatology is represented by 65 frequency classes of geostrophic wind that were selected as equiangular direction sectors and speed intervals with equal frequency in a sector. The results ar...

  10. Multilevel converters for 10 MW Wind Turbines

    DEFF Research Database (Denmark)

    Ma, Ke; Blaabjerg, Frede

    2011-01-01

    Several promising multi-level converter configurations for 10 MW Wind Turbines both with direct drive and one-stage gear box drive using Permanent Magnet Synchronous Generator (PMSG) are proposed, designed and compared. Reliability is a crucial indicator for large scale wind power converters...

  11. Dynamic Phase Compensation of wind turbines

    DEFF Research Database (Denmark)

    Soerensen, P.; Skaarup, J.; Iov, Florin

    2004-01-01

    This paper describes a dynamic phase compensation unit for a wind turbine with directly connected induction generators. The compensation unit is based on thyristor switched capacitors, where conventional wind turbine compensations use mechanical contactors to switch the capacitors. The unit modules...

  12. The Wind Energy Potential of Iceland

    Science.gov (United States)

    Nawri, Nikolai; Nína Petersen, Guðrún; Bjornsson, Halldór; Hahmann, Andrea N.; Jónasson, Kristján; Bay Hasager, Charlotte; Clausen, Niels-Erik

    2014-05-01

    While Iceland has an abundant wind energy resource, its use for electrical power production has so far been limited. Electricity in Iceland is generated primarily from hydro- and geothermal sources, and adding wind energy has so far not been considered practical or even necessary. However, wind energy is becoming a more viable option, as opportunities for new hydro- or geothermal power installations become limited. In order to obtain an estimate of the wind energy potential of Iceland, a wind atlas has been developed as part of the joint Nordic project 'Improved Forecast of Wind, Waves and Icing' (IceWind). Downscaling simulations performed with the Weather Research and Forecasting (WRF) model were used to determine the large-scale wind energy potential of Iceland. Local wind speed distributions are represented by Weibull statistics. The shape parameter across Iceland varies between 1.2 and 3.6, with the lowest values indicative of near-exponential distributions at sheltered locations, and the highest values indicative of normal distributions at exposed locations in winter. Compared with summer, average power density in winter is increased throughout Iceland by a factor of 2.0 - 5.5. In any season, there are also considerable spatial differences in average wind power density. Relative to the average value within 10 km of the coast, power density across Iceland varies between 50 - 250%, excluding glaciers, or between 300 - 1500 W m-2 at 50 m above ground level in winter. At intermediate elevations of 500 - 1000 m above mean sea level, power density is independent of the distance to the coast. In addition to seasonal and spatial variability, differences in average wind speed and power density also exist for different wind directions. Along the coast in winter, power density of onshore winds is higher by 100 - 700 W m-2 than that of offshore winds. The regions with the highest average wind speeds are impractical for wind farms, due to the distances from road

  13. Pre-feasibility study of 80mw onshore wind farm

    International Nuclear Information System (INIS)

    Almas, M.S.

    2014-01-01

    This paper discusses a pre-feasibility study of 80MW onshore wind farm in the KPK (Khyber Pakhtunkhwa) province previously known as NWFP (North West Frontier) Province of Pakistan. The realistic data of wind speed is collected from Laboratory of Meteorology and Climatology (University of the Punjab) to study the feasibility of wind farm. Detailed analysis of wind turbines from four different manufacturers is carried out together with justifications of selecting a particular wind turbine. Issues related to site selection, wind farm civil foundation, recommendations for a particular choice of tower along with environmental effects are presented. Wind data analysis is carried out by using WINDROSE PRO software to determine the resultant direction of wind at the selected site for wind farm layout. The wind distribution at hub height of the wind turbine is calculated and is used to compute annual power production by the wind farm using power curves of the wind turbine. Electrical network integration issues of wind farm to the external grid are studied and the optimum point of connection is proposed. Finally, economic analysis of the whole wind farm project depending upon the LCC (Life Cycle Cost Analysis) is presented and the feasibility of the project from the investor's point of view is identified. The study concludes that the cost per kilowatt hour of electricity generated by this wind power plant will be 10.4 PKR/kWh and the payback period for the whole project is about 11.2 years. (author)

  14. Influence of wind loading

    OpenAIRE

    MAVLONOV RAVSHANBEK ABDUJABBOROVICH; VAKKASOV KHAYRULLO SAYFULLAHANOVICH

    2015-01-01

    Each wind load is determined by a probabilistic-statistical method based on the concept of “equivalent static wind load”, on the assumption that structural frames and components/cladding behave elastically in strong wind.

  15. Wind energy program overview

    International Nuclear Information System (INIS)

    1992-02-01

    This overview emphasizes the amount of electric power that could be provided by wind power rather than traditional fossil fuels. New wind power markets, advances in technology, technology transfer, and wind resources are some topics covered in this publication

  16. Denmark Wind Energy Programme

    DEFF Research Database (Denmark)

    Shen, Wen Zhong

    2014-01-01

    In this paper, a summary of some ongoing wind energy projects in Denmark is given. The research topics comprise computational model development, wind turbine design, low noise airfoil and blade design, control device development, wake modelling, and wind farm layout optimization.......In this paper, a summary of some ongoing wind energy projects in Denmark is given. The research topics comprise computational model development, wind turbine design, low noise airfoil and blade design, control device development, wake modelling, and wind farm layout optimization....

  17. Superconducting Wind Turbine Generators

    OpenAIRE

    Yunying Pan; Danhzen Gu

    2016-01-01

    Wind energy is well known as a renewable energy because its clean and less polluted characteristic, which is the foundation of development modern wind electricity. To find more efficient wind turbine is the focus of scientists around the world. Compared from conventional wind turbines, superconducting wind turbine generators have advantages at zero resistance, smaller size and lighter weight. Superconducting wind turbine will inevitably become the main trends in this area. This paper intends ...

  18. Wind resource modelling for micro-siting - Validation at a 60-MW wind farm site

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, J.C.; Gylling Mortensen, N. [Risoe National Lab., Wind Energy and Atmospheric Physics Dept., Roskilde (Denmark); Said, U.S. [New and Renewable Energy Authority, Cairo (Egypt)

    1999-03-01

    This paper investigates and validates the applicability of the WAsP-model for layout optimization and micro-siting of wind turbines at a given site for a 60-MW wind farm at Zafarana at the Gulf of Suez in Egypt. Previous investigations show large gradients in the wind climate within the area. For the design and optimization of the wind farm it was found necessary to verify the WAsP extrapolation of wind atlas results from 2 existing meteorological masts located 5 and 10 km, respectively, from the wind farm site. On-site measurements at the 3.5 x 3.5 km{sup 2} wind farm site in combination with 7 years of near-site wind atlas measurements offer significant amounts of data for verification of wind conditions for micro-siting. Wind speeds, wind directions, turbulence intensities and guests in 47.5 m a.g.l. have been measured at 9 locations across the site. Additionally, one of the site masts is equipped as a reference mast, measuring both vertical profiles of wind speed and temperature as well as air pressure and temperature. The exercise is further facilitated by the fact that winds are highly uni-directional; the north direction accounting for 80-90% of the wind resource. The paper presents comparisons of 5 months of on-site measurements and modeled predictions from 2 existing meteorological masts located at distances of 5 and 10 km, respectively, from the wind farm site. Predictions based on terrain descriptions of the Wind Atlas for the Gulf of Suez 1991-95 showed over-predictions of wind speeds of 4-10%. With calibrated terrain descriptions, made based on measured data and a re-visit to critical parts of the terrain, the average prediction error of wind speeds was reduced to about 1%. These deviations are smaller than generally expected for such wind resource modeling, clearly documenting the validity of using WAsP modeling for micro-siting and layout optimization of the wind farm. (au)

  19. Generation of Kappa Distributions in Solar Wind at 1 au

    Science.gov (United States)

    Livadiotis, G.; Desai, M. I.; Wilson, L. B., III

    2018-02-01

    We examine the generation of kappa distributions in the solar wind plasma near 1 au. Several mechanisms are mentioned in the literature, each characterized by a specific relationship between the solar wind plasma features, the interplanetary magnetic field (IMF), and the kappa index—the parameter that governs the kappa distributions. This relationship serves as a signature condition that helps the identification of the mechanism in the plasma. In general, a mechanism that generates kappa distributions involves a single or a series of stochastic or physical processes that induces local correlations among particles. We identify three fundamental solar wind plasma conditions that can generate kappa distributions, noted as (i) Debye shielding, (ii) frozen IMF, and (iii) temperature fluctuations, each one prevailing in different scales of solar wind plasma and magnetic field properties. Moreover, our findings show that the kappa distributions, and thus, their generating mechanisms, vary significantly with solar wind features: (i) the kappa index has different dependence on the solar wind speed for slow and fast modes, i.e., slow wind is characterized by a quasi-constant kappa index, κ ≈ 4.3 ± 0.7, while fast wind exhibits kappa indices that increase with bulk speed; (ii) the dispersion of magnetosonic waves is more effective for lower kappa indices (i.e., further from thermal equilibrium); and (iii) the kappa and polytropic indices are positively correlated, as it was anticipated by the theory.

  20. Wind turbines, is it just wind?

    International Nuclear Information System (INIS)

    Boiteux, M.

    2012-01-01

    The author first outlines that wind energy is not only random, but almost absent in extreme situations when it would be needed (for example and notably, very cold weather without wind). He suggests the association of a gas turbine to each wind turbine, so that the gas turbine will replace non operating wind turbines. He notices that wind turbines are not proximity energy as they were said to be, and that profitability in fact requires tens of grouped giant wind turbines. He also outlines the high cost of construction of grids for the connection of these wind turbines. Thus, he states that wind energy is far from being profitable in the present conditions of electricity tariffs in France

  1. Transport of Venusian rolling 'stones' by wind?

    Science.gov (United States)

    Greeley, R.; Marshall, J. R.

    1985-02-01

    Simulations of Venusian wind processes are described which show that particles are moved by 'rolling' at wind speeds as much as 30 percent lower than those required for saltation threshold. This mode of wind transport is only observed for sustained periods in water on earth; thus, there are similarities between aqueous fluid transport on earth and atmospheric transport on Venus. The formation of small sand ridges and grooves oriented parallel to the wind direction is associated with the rolling of grains in Venusian simulations and these structures may be unique aeolian features on Venus.

  2. IS CROATIAN HEALTHCARE SYSTEM READY TO PERFORM IN THE MARKET CONDITIONS PREVAILING IN THE EUROPEAN UNION?

    OpenAIRE

    Nevenka Kovac

    2013-01-01

    As Croatia is nearing its accession to the EU, it is facing a process of implementation of a number of newly introduced legal frameworks which also act to enable access to new market opportunities for certain industries. The most important Directive concerning healthcare providers is Directive 2011/24 on cross-border healthcare, which grants the patients freedom of choice of providers in another EU member state given that the necessary standards of quality and safety are met. A member state i...

  3. Advanced structural wind engineering

    CERN Document Server

    Kareem, Ahsan

    2013-01-01

    This book serves as a textbook for advanced courses as it introduces state-of-the-art information and the latest research results on diverse problems in the structural wind engineering field. The topics include wind climates, design wind speed estimation, bluff body aerodynamics and applications, wind-induced building responses, wind, gust factor approach, wind loads on components and cladding, debris impacts, wind loading codes and standards, computational tools and computational fluid dynamics techniques, habitability to building vibrations, damping in buildings, and suppression of wind-induced vibrations. Graduate students and expert engineers will find the book especially interesting and relevant to their research and work.

  4. Wind for Schools (Poster)

    Energy Technology Data Exchange (ETDEWEB)

    Baring-Gould, I.

    2010-05-01

    As the United States dramatically expands wind energy deployment, the industry is challenged with developing a skilled workforce and addressing public resistance. Wind Powering America's Wind for Schools project addresses these issues by developing Wind Application Centers (WACs) at universities; WAC students assist in implementing school wind turbines and participate in wind courses, by installing small wind turbines at community "host" schools, by implementing teacher training with interactive curricula at each host school. This poster provides an overview of the first two years of the Wind for Schools project, primarily supporting activities in Colorado, Kansas, Nebraska, South Dakota, Montana, and Idaho.

  5. Evaluating Tilt for Wind Plants

    Energy Technology Data Exchange (ETDEWEB)

    Annoni, Jennifer [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Scholbrock, Andrew K. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Churchfield, Matthew J. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Fleming, Paul A. [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-07-03

    The objective of this work is to demonstrate the feasibility of tilt in a wind plant. Tilt control, much like other wind plant control strategies, has the potential to improve the performance of a wind plant. Tilt control uses the tilt angle of the turbine to direct the wake above or below the downstream turbines. This paper presents a study of tilt in two- and three-turbine arrays. Specifically, the authors show that the power production of a two-turbine array can be increased by tilting turbines in a specific orientation. When adding more turbines, as is shown with the three-turbine array, the overall percentage of power gain increases. This outcome deviates from some of the results seen in typical wind plant control strategies. Finally, we discuss the impact this type of control strategy has on the aerodynamics in a wind plant. This analysis demonstrates that a good understanding of wake characteristics is necessary to improve the plant's performance. A tilt strategy such as the one presented in this paper may have implications for future control/optimization studies including optimization of hub heights in a wind plant and analysis of deep array effects.

  6. Wind power in political whirlwind

    International Nuclear Information System (INIS)

    Morch, Stein

    2002-01-01

    In Norway, according to this article, shifting fair wind and head wind for wind power have changed to unpredictable political whirlwinds. That is, there is great uncertainty with respect to further development of wind power in Norway as well as in nearby markets such as Sweden, Denmark and the Netherlands. The government, represented by Enova, has announced reduced investment grants, and so the realization of a ''green'' market, at home or across the frontiers, becomes very important. The political goal of producing 3 TWh of wind power per year by 2010 apparently is still valid, but it is difficult to see any robust and convincing clarity when it comes to policy instruments and economical frames that will make it possible to reach that goal. In its directive on renewable energy sources in the energy generation, the EU has quoted a total increase in capacity from 14 percent in 1997 to 22 percent in 2010. This has been shared among the member countries as indicative targets and there is great freedom in the selection of policy instruments. At the end of 2002, the wind power production in Norway is 0.3 TWh/year

  7. BOREAS AFM-06 Mean Wind Profile Data

    Science.gov (United States)

    Wilczak, James; Hall, Forrest G. (Editor); Newcomer, Jeffrey A. (Editor); Smith, David E. (Technical Monitor)

    2000-01-01

    The Boreal Ecosystem-Atmosphere Study (BOREAS) Airborne Fluxes and Meteorology (AFM)-6 team from the National Oceanic and Atmospheric Administration/Environment Technology Laboratory (NOAA/ETL) operated a 915-MHz wind/Radio Acoustic Sounding System (RASS) profiler system in the Southern Study Area (SSA) near the Old Jack Pine (OJP) tower from 21 May 1994 to 20 Sep 1994. The data set provides wind profiles at 38 heights, containing the variables of wind speed; wind direction; and the u-, v-, and w-components of the total wind. The data are stored in tabular ASCII files. The mean wind profile data are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The data files are available on a CD-ROM (see document number 20010000884).

  8. Class Generation for Numerical Wind Atlases

    DEFF Research Database (Denmark)

    Cutler, N.J.; Jørgensen, B.H.; Ersbøll, Bjarne Kjær

    2006-01-01

    A new optimised clustering method is presented for generating wind classes for mesoscale modelling to produce numerical wind atlases. It is compared with the existing method of dividing the data in 12 to 16 sectors, 3 to 7 wind-speed bins and dividing again according to the stability...... adapting to the local topography. The purpose of forming classes is to minimise the computational time for the mesoscale model while still representing the synoptic climate features. Only tried briefly in the past, clustering has traits that can be used to improve the existing class generation method...... at specific sites. The sources are The New Irish Wind Resource Atlas and the Wind Atlas for the Gulf of Suez. The new clustering method has the ability to include wind-speed, direction and thermal stability from different heights for the classification. It is shown that the clustering method is able...

  9. Adaptive Extremum Control and Wind Turbine Control

    DEFF Research Database (Denmark)

    Ma, Xin

    1997-01-01

    This thesis is divided into two parts, i.e., adaptive extremum control and modelling and control of a wind turbine. The rst part of the thesis deals with the design of adaptive extremum controllers for some processes which have the behaviour that process should have as high e ciency as possible...... in parameters, and thus directly lends itself to parameter estimation and adaptive control. The extremum control law is derived based on static optimization of a performance function. For a process with nonlinearity at output the intermediate signal between the linear part and nonlinear part plays an important...... role. If it can be emphasis on control design. The models have beenvalidated by experimental data obtained from an existing wind turbine. The e ective wind speed experienced by the rotor of a wind turbine, which is often required by some control methods, is estimated by using a wind turbine as a wind...

  10. The Wind Energy Potential of Iceland

    DEFF Research Database (Denmark)

    Nawri, Nikolai; Petersen, Guðrún Nína; Björnsson, Halldór

    2014-01-01

    of 500 e1000 m above mean sea level, power density is independent of the distance to the coast. In addition to seasonal and spatial variability, differences in average wind speed and power density also exist for different wind directions. Along the coast in winter, power density of onshore winds......, there are also considerable spatial differences in average wind power density. Relative to the average value within 10 km of the coast, power density across Iceland varies between 50 and 250%, excluding glaciers, or between 300 and 1500 W m_2 at 50 m above ground level in winter. At intermediate elevations...... is higher by 100 e700 W m_2 than that of offshore winds. Based on these results, 14 test sites were selected for more detailed analyses using the Wind Atlas Analysis and Application Program (WAsP). © 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license...

  11. Lightning protection for wind turbines in Vietnam

    Directory of Open Access Journals (Sweden)

    Thuan Nguyen

    2017-01-01

    Full Text Available Wind energy has become increasingly important in the total electrical energy supply mix in Vietnam over the last few years. Small, kW turbines were installed in isolated areas a decade ago, while wind farms of several MW to few hundred MW are now being connected directly to national grid, with many additional projects in planning or under construction to fulfill an objective of 6% of the total installed capacity by 2030 (approximately 6200 MW of wind energy component. The increase in wind farm generation results in increased damage from lightning. In this paper, the annual frequency of lightning strikes to wind turbines in Vietnam is calculated using electrogeometric model. Reported lightning incidents to three major wind farms in Vietnam are summarized. Possible causes of failure are discussed, and an EMTP simulation for each incident was performed accordingly. The simulations suggest the failure mechanisms as well the potential of improved grounding to reduce lightning induced damage in future windfarms.

  12. Assessment of regional wind energy resources over the Ukraine

    Science.gov (United States)

    Sobchenko, Anastasiia; Khomenko, Inna

    2015-04-01

    The purpose of the study has been to provide a preliminary assessment of different regions of the Ukraine. Investigation is based on thirty-minute wind observations collected through an 8-year period (January 1, 2002 to December 31, 2008) for seven airports of the Ukraine. For renewal of vertical profile of the wind direction and speed radiosounding data were used. By applying of the probabilistic analysis techniques to series of wind data and the wind extreme values, yearly, monthly and diurnal variation of wind speed and direction are derived. Based on these results theoretical distribution functions and exceeding probability are found for each airport. The statistic characteristics obtained were compared with the correspondent values provided for 1936-1960 and 1961-1990 periods and site-related temporal changeability is determined. For each period considered assessment of wind resources at 10 meters height is carried out. Since the geostrophic wind are frequently used to calculate the surface wind at heights between 10 and 200 m, in the research the distribution of the geostrophic wind for each airport were determined. Comparative analysis of distribution and statistic characteristics of geostrophic and surface winds are made. The relation between a set of values of the geostrophic wind and a set of values of the surface wind speed was provided for each airport. Using different relationship for variation of wind speed with height wind resources at heights between 10 and 200 were assessed. The results obtained show that with the lapse of the time wind speed and wind resources is decreased half the size. It is reflected general tendencies in the wind speed changeability over the European territory. Places which are most perspective for wind turbine installation are off-shore sites such as Odessa, and sites situated in the Crimea mountain (Simferopol) and the Donetsk ridge (Donetsk). The results derived in the contribution may be used for modeling and mapping wind

  13. Wind energy assessment and wind farm simulation in Triunfo - Pernambuco, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Lima, Laerte; Filho, Celso

    2010-09-15

    The Triunfo wind's characterization, in Pernambuco state, situated in Brazilian northeast, and wind power potential assessment study shows a average wind speed of 11.27 m / s, predominant Southeast wind direction, average wind power density of 1672 W/m2 and Weibull parameters shape and scale equal to 2,0 and 12,7 m/s. The wind farm was simulated by using 850kW wind turbines (total of 20MW). The simulated shows AEP of 111,4 GWh, Cf of 62% and 5462 hours of operation by year. The economical simulated results, shows Pay-back of 3 years, TIR = 47% and VAN = 85.506kEuro booths @ 20 years time period.

  14. WIND PROTECTION OF LANDSCAPE ARCHITECTURE

    Directory of Open Access Journals (Sweden)

    Trubitsyna Natalja Anatolevna

    2017-07-01

    shown in the form of sculptures moving from air streams, which also change the speed and direction of the wind. All this is generalized in further directions of research within the framework of the designated terrain theme, bioclimatic comfort and wind protection.

  15. Wind resource assessment: San Nicolas Island, California

    Energy Technology Data Exchange (ETDEWEB)

    McKenna, E. [National Renewable Energy Lab., Golden, CO (United States); Olsen, T.L. [Timothy L. Olsen Consulting, (United States)

    1996-01-01

    San Nicolas Island (SNI) is the site of the Navy Range Instrumentation Test Site which relies on an isolated diesel-powered grid for its energy needs. The island is located in the Pacific Ocean 85 miles southwest of Los Angeles, California and 65 miles south of the Naval Air Weapons Station (NAWS), Point Mugu, California. SNI is situated on the continental shelf at latitude N33{degree}14` and longitude W119{degree}27`. It is approximately 9 miles long and 3.6 miles wide and encompasses an area of 13,370 acres of land owned by the Navy in fee title. Winds on San Nicolas are prevailingly northwest and are strong most of the year. The average wind speed is 7.2 m/s (14 knots) and seasonal variation is small. The windiest months, March through July, have wind speeds averaging 8.2 m/s (16 knots). The least windy months, August through February, have wind speeds averaging 6.2 m/s (12 knots).

  16. Wind Power: A Turning Point. Worldwatch Paper 45.

    Science.gov (United States)

    Flavin, Christopher

    Recent studies have shown wind power to be an eminently practical and potentially substantial source of electricity and direct mechanical power. Wind machines range from simple water-pumping devices made of wood and cloth to large electricity producing turbines with fiberglass blades nearly 300 feet long. Wind is in effect a form of solar…

  17. Microcontroller-based data logging instrumentation system for wind ...

    African Journals Online (AJOL)

    The collected data were transmitted to a PC through an RS-232 serial interface, and were processed using the 208W Data logger support software. Wind speed and direction measured by the microcontroller-based data logging system were analyzed using line graphs, scatter correlation charts and wind roses. Wind speeds ...

  18. Oceansat–2 and RAMA buoy winds: A comparison

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 122; Issue 6. Oceansat–2 and RAMA buoy winds: A ... In the complete annual cycle (2011), the monthly mean root mean square differences in the wind speed and wind direction were less than ∼2.5 ms−1 and ∼20°, respectively. The better match between the ...

  19. Power fluctuations from large wind farms - Final report

    Energy Technology Data Exchange (ETDEWEB)

    Soerensen, Poul; Pinson, P.; Cutululis, N.A.; Madsen, Henrik; Jensen, Leo Enrico; Hjerrild, J.; Heyman Donovan, M.; Vigueras-ROdriguez, A.

    2009-08-15

    Experience from power system operation with the first large offshore wind farm in Denmark: Horns Rev shows that the power from the wind farm is fluctuating significantly at certain times, and that this fluctuation is seen directly on the power exchange between Denmark and Germany. This report describes different models for simulation and prediction of wind power fluctuations from large wind farms, and data acquired at the two large offshore wind farms in Denmark are applied to validate the models. Finally, the simulation model is further developed to enable simulations of power fluctuations from several wind farms simultaneously in a larger geographical area, corresponding to a power system control area. (au)

  20. Prescribed wind shear modelling with the actuator line technique

    DEFF Research Database (Denmark)

    Mikkelsen, Robert Flemming; Sørensen, Jens Nørkær; Troldborg, Niels

    2007-01-01

    A method for prescribing arbitrary steady atmospheric wind shear profiles combined with CFD is presented. The method is furthermore combined with the actuator line technique governing the aerodynamic loads on a wind turbine. Computation are carried out on a wind turbine exposed to a representative...... steady atmospheric wind shear profile with and without wind direction changes up through the atmospheric boundary layer. Results show that the main impact on the turbine is captured by the model. Analysis of the wake behind the wind turbine, reveal the formation of a skewed wake geometry interacting...

  1. Wind flow around a church - Case study

    Science.gov (United States)

    Jamińska-Gadomska, Paulina; Lipecki, Tomasz; Podgórski, Jerzy

    2018-01-01

    The paper presents results of CFD analysis performed to check the influence of wind action on a bell tower of a church. The geometry of the structure is quite complex therefore it is very hard to calculate wind load basing only on codes recommendations. The modelled geometry contains whole structure of the church including the bell tower. Results presented in this paper are focused on co-called "Venturi-effect" represented by the flow around the bell tower. CFD simulations were performed for two inflow wind directions of opposite senses. This led to two cases of converging and diverging walls of the bell tower in relation to the wind flow direction. Such analysis was performed to check if the wind speed increases between the walls of the bell tower.

  2. False-positive findings in mammography screening induces short-term distress - breast cancer-specific concern prevails longer

    DEFF Research Database (Denmark)

    Aro, A R; Pilvikki Absetz, S; van Elderen, T M

    2000-01-01

    -ups at 2 and 12 months postscreening. At 2 months, there was a moderate multivariate effect of group on distress; and intrusive thinking and worry about breast cancer, in particular, were most frequent amongst the false positives. Intrusive thinking still prevailed at 12 months, in addition to a higher...... findings (n=1407), false-positive findings (n=492) and referents from outside the screening programme (n=1718, age 48-49 years). Distress was measured as illness worry, anxiety, depression, cancer beliefs and early detection behaviour. Measurements were one month before screening invitation with follow...... perceived breast cancer risk and susceptibility. Distress related to screening and false-positive findings seems to be moderate, but prevailing cancer-specific concerns call for improvements in screening programmes....

  3. Wind power development field test project under Japan Sea Museum program. Detailed wind characteristics survey; Nihonkai Museum koso ni okeru furyoku kaihatsu field test jigyo (fukyo seisa) hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-11-01

    A detailed wind characteristics survey was conducted at Kaio-machi, Niiminato-shi, Toyama Prefecture, on the assumption that a wind power generation system would be constructed. The survey was a 1-year project from October 1998 through September 1999, and wind characteristics such as the average wind speed, average wind direction, standard deviation of wind velocity, and the maximum instantaneous wind speed were observed. The observation point was fixed at 20m above ground, the minimum time unit for observation was 10 minutes, and the 10-minute average value was defined as the measured value. For the maximum instantaneous wind speed, the minimum time unit for observation was set to be 2 seconds. The yearly average wind speed was 3.7m/s and the maximum wind speed in the period was 26m/s. Winds came prevalently from SW (17.5%), and then from WSW (11.4%) and NNE (10.2%). The wind axis was in the NE-SW direction with a total wind direction occurrence rate of 62.0%. Turbulence intensity was 0.15 at wind speed 2.0m/s or more and 0.14 at wind speed 4.0m/s or more. Estimated wind turbine yearly operating factors of 32-79% were obtained using rated values of a 150kW, 300kW, and 750kW-class wind turbines. (NEDO)

  4. Wind Directions in the Polish Tatras,

    Science.gov (United States)

    1982-01-26

    The study of anemometric conditions in the iatra Aoun- tains with the usually available observation data presents a rather difficult problem for two...year are presented in Table 2 and Fig. 1. Analysis of the anemometric conditions in the Polish Ta- tras and at 2odhale, on the basis of the observational...Vol. 29, 1947. 9. Milata, W. "The Foehn," Wierchy, Vol. 20, 1950. 10. Orlicz, M. " Anemometric Conditions on Peaks in the 2atras," Wiad. Sluzhby Hydro

  5. Direct Statistical Thermal Wind Estimation Procedure

    Science.gov (United States)

    1989-03-10

    1 . Althloti1 tourI other- mini mit1lation criteria were ev aluated inI that reference. there w as not a SLtICIent i11vIrOVe:illent uing1 the mlore...position x,. i = 1,...,N , where x = (x1 , x2) define a two- dimensional regular grid Find a plane : f(x = a + bx1 + cx 2 = d T X, (D.1-1) D-I wliere: x...Equation D. I-I defines a plane w% hose gradient, (b c). is an estimate of the radiance gra- dient at the center of the data grid expressed in the data

  6. Robust Kalman filter design for predictive wind shear detection

    Science.gov (United States)

    Stratton, Alexander D.; Stengel, Robert F.

    1991-01-01

    Severe, low-altitude wind shear is a threat to aviation safety. Airborne sensors under development measure the radial component of wind along a line directly in front of an aircraft. In this paper, optimal estimation theory is used to define a detection algorithm to warn of hazardous wind shear from these sensors. To achieve robustness, a wind shear detection algorithm must distinguish threatening wind shear from less hazardous gustiness, despite variations in wind shear structure. This paper presents statistical analysis methods to refine wind shear detection algorithm robustness. Computational methods predict the ability to warn of severe wind shear and avoid false warning. Comparative capability of the detection algorithm as a function of its design parameters is determined, identifying designs that provide robust detection of severe wind shear.

  7. Wind turbine/generator set and method of making same

    Science.gov (United States)

    Bevington, Christopher M.; Bywaters, Garrett L.; Coleman, Clint C.; Costin, Daniel P.; Danforth, William L.; Lynch, Jonathan A.; Rolland, Robert H.

    2013-06-04

    A wind turbine comprising an electrical generator that includes a rotor assembly. A wind rotor that includes a wind rotor hub is directly coupled to the rotor assembly via a simplified connection. The wind rotor and generator rotor assembly are rotatably mounted on a central spindle via a bearing assembly. The wind rotor hub includes an opening having a diameter larger than the outside diameter of the central spindle adjacent the bearing assembly so as to allow access to the bearing assembly from a cavity inside the wind rotor hub. The spindle is attached to a turret supported by a tower. Each of the spindle, turret and tower has an interior cavity that permits personnel to traverse therethrough to the cavity of the wind rotor hub. The wind turbine further includes a frictional braking system for slowing, stopping or keeping stopped the rotation of the wind rotor and rotor assembly.

  8. 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...... penetration beforehand. This paper proposes a novel hybrid intelligent algorithm approach to directly formulate optimal prediction intervals of wind power generation based on extreme learning machine and particle swarm optimization. Prediction intervals with Associated confidence levels are generated through...

  9. Wind engineering in Africa

    NARCIS (Netherlands)

    Wisse, J.A.; Stigter, C.J.

    2007-01-01

    The International Association for Wind Engineering (IAWE) has very few contacts in Africa, the second-largest continent. This paper reviews important wind-related African issues. They all require data on wind climate, which are very sparse in Africa. Wind engineering in Africa can assist in

  10. Wind energy; Energie eolienne

    Energy Technology Data Exchange (ETDEWEB)

    Vachey, C.

    2000-05-01

    This public information paper presents the wind energy resource in the Languedoc Roussillon region, explains how a wind turbine works, the different types of utilization and the cost of the wind energy. The environmental impacts of the wind energy, on the noise and the landscape, are also discussed. (A.L.B.)

  11. Investigation of wind characteristics and assessment of wind energy potential for Waterloo region, Canada

    International Nuclear Information System (INIS)

    Li Meishen; Li Xianguo

    2005-01-01

    Wind energy becomes more and more attractive as one of the clean renewable energy resources. Knowledge of the wind characteristics is of great importance in the exploitation of wind energy resources for a site. It is essential in designing or selecting a wind energy conversion system for any application. This study examines the wind characteristics for the Waterloo region in Canada based on a data source measured at an elevation 10 m above the ground level over a 5-year period (1999-2003) with the emphasis on the suitability for wind energy technology applications. Characteristics such as annual, seasonal, monthly and diurnal wind speed variations and wind direction variations are examined. Wind speed data reveal that the windy months in Waterloo are from November to April, defined as the Cold Season in this study, with February being the windiest month. It is helpful that the high heating demand in the Cold Season coincides with the windy season. Analysis shows that the day time is the windy time, with 2 p.m. in the afternoon being the windiest moment. Moreover, a model derived from the maximum entropy principle (MEP) is applied to determine the diurnal, monthly, seasonal and yearly wind speed frequency distributions, and the corresponding Lagrangian parameters are determined. Based on these wind speed distributions, this study quantifies the available wind energy potential to provide practical information for the application of wind energy in this area. The yearly average wind power density is 105 W/m 2 . The day and night time wind power density in the Cold Season is 180 and 111 W/m 2 , respectively

  12. The sound of high winds. The effect of atmospheric stability on wind turbine sound and microphone noise

    International Nuclear Information System (INIS)

    Van den Berg, G.P.

    2006-01-01

    In this thesis issues are raised concerning wind turbine noise and its relationship to altitude dependent wind velocity. The following issues are investigated: what is the influence of atmospheric stability on the speed and sound power of a wind turbine?; what is the influence of atmospheric stability on the character of wind turbine sound?; how widespread is the impact of atmospheric stability on wind turbine performance: is it relevant for new wind turbine projects; how can noise prediction take this stability into account?; what can be done to deal with the resultant higher impact of wind turbine sound? Apart from these directly wind turbine related issues, a final aim was to address a measurement problem: how does wind on a microphone affect the measurement of the ambient sound level?

  13. Offshore Wind Farms

    DEFF Research Database (Denmark)

    Lundtang Petersen, Erik; Hasager, Charlotte Bay; Courtney, Michael

    2015-01-01

    The technology behind constructing wind farms offshore began to develop in 1991 when the Vindeby wind farm was installed off the Danish coast (11 Bonus 450 kW turbines). Resource assessment, grid connection, and wind farm operation are significant challenges for offshore wind power just...... concern are the problems associated with locating the turbines close together in a wind farm and the problems of placing several large wind farms in a confined area. The environmental impacts of offshore wind farms are also treated, but not the supply chain, that is, the harbors, the installation vessels...

  14. Wake losses optimization of offshore wind farms with moveable floating wind turbines

    International Nuclear Information System (INIS)

    Rodrigues, S.F.; Teixeira Pinto, R.; Soleimanzadeh, M.; Bosman, Peter A.N.; Bauer, P.

    2015-01-01

    Highlights: • We present a layout optimization framework for wind farms with moveable turbines. • Using moveable wind turbines in optimized layouts maximizes energy production. • Turbine and wind farm designers should cooperate to optimize offshore wind projects. - Abstract: In the future, floating wind turbines could be used to harvest energy in deep offshore areas where higher wind mean speeds are observed. Currently, several floating turbine concepts are being designed and tested in small scale projects; in particular, one concept allows the turbine to move after installation. This article presents a novel layout optimization framework for wind farms composed of moveable floating turbines. The proposed framework uses an evolutionary optimization strategy in a nested configuration which simultaneously optimizes the anchoring locations and the wind turbine position within the mooring lines for each individual wind direction. The results show that maximum energy production is obtained when moveable wind turbines are deployed in an optimized layout. In conclusion, the framework represents a new design optimization tool for future offshore wind farms composed of moveable floating turbines

  15. Applicability of Synthetic Aperture Radar Wind Retrievals on Offshore Wind Resources Assessment in Hangzhou Bay, China

    Directory of Open Access Journals (Sweden)

    Rui Chang

    2014-05-01

    Full Text Available In view of the high cost and sparse spatial resolution of offshore meteorological observations, ocean winds retrieved from satellites are valuable in offshore wind resource assessment as a supplement to in situ measurements. This study examines satellite synthetic aperture radar (SAR images from ENVISAT advanced SAR (ASAR for mapping wind resources with high spatial resolution. Around 181 collected pairs of wind data from SAR wind maps and from 13 meteorological stations in Hangzhou Bay are compared. The statistical results comparing in situ wind speed and SAR-based wind speed show a standard deviation (SD of 1.99 m/s and correlation coefficient of R = 0.67. The model wind directions, which are used as input for the SAR wind speed retrieval, show a high correlation coefficient (R = 0.89 but a large standard deviation (SD = 42.3° compared to in situ observations. The Weibull probability density functions are compared at one meteorological station. The SAR-based results appear not to estimate the mean wind speed, Weibull scale and shape parameters and wind power density from the full in situ data set so well due to the lower number of satellite samples. Distributions calculated from the concurrent 81 SAR and in situ samples agree well.

  16. Comparative study of the behavior of wind-turbines in a wind farm

    Energy Technology Data Exchange (ETDEWEB)

    Migoya, Emilio; Crespo, Antonio; Garcia, Javier; Manuel, Fernando; Jimenez, Angel [Universidad Politecnica de Madrid (UPM), Madrid (Spain). Departamento de Ingenieria Energetica y Fluidomecanica, Laboratorio de Mecanica de Fluidos; Moreno, Fermin [Comision Nacional de la Energia, Madrid (Spain); Costa, Alexandre [Energia Eolica, Division de Energias Renovables, CIEMAT, Madrid (Spain)

    2007-10-15

    The Sotavento wind farm is an experimental wind farm which has different types of wind turbines. It is located in an area whose topography is moderately complex, and where wake effects can be significant. One of the objectives of Sotavento wind farm is to compare the performances of the different machines; particularly regarding power production, maintenance and failures. However, because of wakes and topography, the different machines are not working under identical conditions. Two linearized codes have been used to estimate topography effects: UPMORO and WAsP. For wind directions in which topography is abrupt, the non-linear flow equations have been solved with the commercial code FLUENT, although the results are only qualitatively used. For wake effects, the UPMPARK code has been applied. As a result, the incident velocity over each wind turbine is obtained, and the power production is estimated by means of the power curve of each machine. Experimental measurements give simultaneously the wind characteristics at the measuring stations, the wind velocity, at the nacelle anemometer, and the power production of each wind turbine. These experimental results are employed to validate the numerical predictions. The main objective of this work is to deduce and validate a relationship between the wind characteristics measured in the anemometers and the wind velocity and the power output in each machine. (author)

  17. Analysing wind farm efficiency on complex terrains

    International Nuclear Information System (INIS)

    Castellani, Francesco; Astolfi, Davide; Terzi, Ludovico; Hansen, Kurt Schaldemose; Rodrigo, Javier Sanz

    2014-01-01

    Actual performances of onshore wind farms are deeply affected both by wake interactions and terrain complexity: therefore monitoring how the efficiency varies with the wind direction is a crucial task. Polar efficiency plot is therefore a useful tool for monitoring wind farm performances. The approach deserves careful discussion for onshore wind farms, where orography and layout commonly affect performance assessment. The present work deals with three modern wind farms, owned by Sorgenia Green, located on hilly terrains with slopes from gentle to rough. Further, onshore wind farm of Nprrekffir Enge has been analysed as a reference case: its layout is similar to offshore wind farms and the efficiency is mainly driven by wakes. It is shown and justified that terrain complexity imposes a novel and more consistent way for defining polar efficiency. Dependency of efficiency on wind direction, farm layout and orography is analysed and discussed. Effects of atmospheric stability have been also investigated through MERRA reanalysis data from NASA satellites. Monin-Obukhov Length has been used to discriminate climate regimes

  18. Pilot project wind power - Large scale wind power in northern Sweden; Pilotprojekt vindkraft - Storskalig vindkraft i norra Sverige

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-07-01

    The Swedish Energy Agency granted 2009-04-20 Svevind AB financial aid to implement {sup P}ilot project wind power- Large scale wind power in northern Sweden{sup .} The purpose of the aid is to implement pilot sub-projects in wind power, to to increase knowledge for the larger establishments. The Energy Agency said in its decision that the projects Dragaliden and Gabriel Mountain is of 'great importance for future large-scale development of wind power in Sweden'. The special conditions prevailing in the project, forest environment and cold climate, gives the possibility of studies of wind turbines on birds, reindeer herding and hunting and the more technical aspects, such as de-icing and obstacle lighting. The objectives of the project, in addition to the construction and operation of 32 wind turbines, has been to include evaluating the permit process, studying the social effects around the wind power, to study the impact on small game hunting, perform tests of the de-icing system, investigate impacts on reindeer herding and explain the outcome of the project-generated rural funds. Some of the above sub-projects have been completed, which are reported in this report. For the sub-projects still in progress, the report presents the results to date, until the completion.

  19. Design of a Small Scale Wind Generator for Low Wind Speed Areas ...

    African Journals Online (AJOL)

    Most small scale level wind turbine generators are directly driven system, variable speed, and partially connected power electronic converter system. Choice of such system is to avoid costs associated with gearbox. However, due to low wind speed in most of the tropical countries, synchronous generators with smaller or ...

  20. Blowing in the wind: evaluating wind energy projects on the national forests

    Science.gov (United States)

    Kerry Schlichting; Evan Mercer

    2011-01-01

    The 650 million ac of federal lands are facing increased scrutiny for wind energy development. As a result, the US Forest Service has been directed to develop policies and procedures for siting wind energy projects. We incorporate geospatial site suitability analysis with applicable policy and management principles to illustrate the use of a Spatial Decision Support...

  1. design of a small scale wind generator for low wind speed areas

    African Journals Online (AJOL)

    USER

    the complexity of the drive train there are experimental proposals in literature where a synchronous generator that be able to operate under low wind speed can be directly connected to the end user especially the off-grid population. Hence, the study designed a six pole pairs wind turbine generator using permanent magnet ...

  2. Evaluation of wind flow with a nacelle-mounted, continuous wave wind lidar

    DEFF Research Database (Denmark)

    Medley, John; Barker, Will; Harris, Mike

    2014-01-01

    IR, increasing the confidence in the ZephIR for measuring wind parameters in this configuration. SCADA data from the turbine was combined with measured wind speeds and directions to derive power curves from the mast data (hub-height) and from ZephIR data (hub-height and rotor-equivalent). The rotor...

  3. Wind energy resources assessment for Yanbo, Saudi Arabia

    International Nuclear Information System (INIS)

    Rehman, Shafiqur

    2004-01-01

    The paper presents long term wind data analysis in terms of annual, seasonal and diurnal variations at Yanbo, which is located on the west coast of Saudi Arabia. The wind speed and wind direction hourly data for a period of 14 years between 1970 and 1983 is used in the analysis. The analysis showed that the seasonal and diurnal pattern of wind speed matches the electricity load pattern of the location. Higher winds of the order of 5.0 m/s and more were observed during the summer months of the year and noon hours (09:00 to 16:00 h) of the day. The wind duration availability is discussed as the percent of hours during which the wind remained in certain wind speed intervals or bins. Wind energy calculations were performed using wind machines of sizes 150, 250, 600, 800, 1000, 1300, 1500, 2300 and 2500 kW rated power. Wind speed is found to remain above 3.5 m/s for 69% of the time during the year at 40, 50, 60, and 80 m above ground level. The energy production analysis showed higher production from wind machines of smaller sizes than the bigger ones for a wind farm of 30 MW installed capacity. Similarly, higher capacity factors were obtained for smaller wind machines compared to larger ones

  4. Guide to Using the WIND Toolkit Validation Code

    Energy Technology Data Exchange (ETDEWEB)

    Lieberman-Cribbin, W.; Draxl, C.; Clifton, A.

    2014-12-01

    In response to the U.S. Department of Energy's goal of using 20% wind energy by 2030, the Wind Integration National Dataset (WIND) Toolkit was created to provide information on wind speed, wind direction, temperature, surface air pressure, and air density on more than 126,000 locations across the United States from 2007 to 2013. The numerical weather prediction model output, gridded at 2-km and at a 5-minute resolution, was further converted to detail the wind power production time series of existing and potential wind facility sites. For users of the dataset it is important that the information presented in the WIND Toolkit is accurate and that errors are known, as then corrective steps can be taken. Therefore, we provide validation code written in R that will be made public to provide users with tools to validate data of their own locations. Validation is based on statistical analyses of wind speed, using error metrics such as bias, root-mean-square error, centered root-mean-square error, mean absolute error, and percent error. Plots of diurnal cycles, annual cycles, wind roses, histograms of wind speed, and quantile-quantile plots are created to visualize how well observational data compares to model data. Ideally, validation will confirm beneficial locations to utilize wind energy and encourage regional wind integration studies using the WIND Toolkit.

  5. Class generation for numerical wind atlases

    Energy Technology Data Exchange (ETDEWEB)

    Cutler, N.J.

    2005-07-01

    A new optimised clustering method is presented for generating wind classes for mesoscale modelling to produce numerical wind atlases. It is compared with the existing method of dividing the data in 12-16 sectors, 3-7 wind speed bins and dividing again on the stability of the atmosphere. Wind atlases are typically produced from many years of on-site measurements. Numerical wind atlases are the result of mesoscale model integrations based on synoptic scale wind climates and can be produced in as quickly as a day. 40 years of twice daily NCEPINCAR Reanalysis geostrophic wind data (200 km resolution) is represented in typically around 100 classes, each with a frequency of occurrence. The mean wind speeds and directions in each class is used as input data to force the mesoscale model, which down scales to 5 km resolution while adapting to the local topography. The number of classes is to minimise the computational time for the mesoscale model while still representing the synoptic climate features. Only tried briefly in the past, clustering has traits that can be used to improve the existing class generation method by optimising the representation of the data and by automating the procedure more. The Karlsruhe Atmospheric Mesoscale Model (KAMM) is combined with WASP to produce numerical wind atlases for two sites, Ireland and Egypt. The model results are compared with The New Irish Wind Resource Atlas and wind atlases made from meteorological station measurements in Egypt. The new clustering method has the ability to include wind data from different heights and thermal stability for the classification. The results show that the clustering method is able to produce results at least equivalent to the existing method results for both sites. A refined, general clustering procedure is devised which could improve the results for both sites, where the existing method requires two different parameter settings. (au)

  6. The surface oxidation kinetics of zirconium-niobium alloys and aα-Fe with prevailing cubical texture

    International Nuclear Information System (INIS)

    Mukhambetov, D.G.; Kargin, D.B.; Chalaya, O. V.; Berber, N.N.

    2002-01-01

    It is known, that the kinetics of oxidation of zirconium at formed heating is characterized by two consecutive stages. At the initial stage the thin protecting film will be derived. The relation of its depth from time h (t) is described predominantly by parabolic law. Some time later there can be a transition to the linear law of oxidation. The time moment divided these areas on the kinetic relation is called as a point of break. The film is formed at the second stage, has a developed grid of pores or cracks, can be flake away and be crumbled by losing its protective properties. At the oxidation of the surface shells of the heat generating elements and the technological channels of atomic boilers both stages are proceeded simultaneously. This phenomenon is called modular corrosion. Its consequences can be dangerous for the equipment. Its mechanism is not clear till now. Similar dependencies h(t), with the break point, beginning from which the thin film is transformed into the thick one were found by us at the oxidation α-Fe with prevailing cubical texture. The task of the work was to study the oxide film growth laws in order to clarify the mechanisms of transition of the thin film into the oxide layer on the α-Fe surface and Zr-Nb alloy modular corrosion emergence. Low-carbonate steel with contents 99.43 % of α-Fe was used as a model object of our research. In the texture of the steel surface planar direction [100] was prevalent. Its part accounted for about 40 %. The isothermal air oxidation was carried out in the interval of 450-500 deg. C . Phase composition of the film was determined with X-ray diffraction. The mathematical treatment of the dependencies h(t) obtained by experiment showed that the kinetics of the film growth can be conditionally divided into 4-stages. The initial stage is described by function logarithmic function, the other stages - by the power mode h n =A n ·t, namely, the second stage - is described by function close to cubical (n≅3

  7. Climatic wind tunnel for wind engineering tasks

    Czech Academy of Sciences Publication Activity Database

    Kuznetsov, Sergeii; Pospíšil, Stanislav; Král, Radomil

    2015-01-01

    Roč. 112, 2-B (2015), s. 303-316 ISSN 1897-628X R&D Projects: GA ČR(CZ) GA14-12892S Keywords : climatic tunnel * wind tunnel * atmospheric boundary layer * flow resistance * wind tunnel contraction Subject RIV: JM - Building Engineering https://suw.biblos.pk.edu.pl/resources/i5/i6/i6/i7/i6/r56676/KuznetsovS_ClimaticWind.pdf

  8. Wind Atlas for Egypt

    DEFF Research Database (Denmark)

    Mortensen, Niels Gylling; Said Said, Usama; Badger, Jake

    2006-01-01

    The results of a comprehensive, 8-year wind resource assessment programme in Egypt are presented. The objective has been to provide reliable and accurate wind atlas data sets for evaluating the potential wind power output from large electricityproducing wind turbine installations. The regional wind...... climates of Egypt have been determined by two independent methods: a traditional wind atlas based on observations from more than 30 stations all over Egypt, and a numerical wind atlas based on long-term reanalysis data and a mesoscale model (KAMM). The mean absolute error comparing the two methods is about...... 10% for two large-scale KAMM domains covering all of Egypt, and typically about 5% for several smaller-scale regional domains. The numerical wind atlas covers all of Egypt, whereas the meteorological stations are concentrated in six regions. The Wind Atlas for Egypt represents a significant step...

  9. Wind Atlas for Egypt

    DEFF Research Database (Denmark)

    The results of a comprehensive, 8-year wind resource assessment programme in Egypt are presented. The objective has been to provide reliable and accurate wind atlas data sets for evaluating the potential wind power output from large electricityproducing wind turbine installations. The regional wind...... climates of Egypt have been determined by two independent methods: a traditional wind atlas based on observations from more than 30 stations all over Egypt, and a numerical wind atlas based on long-term reanalysis data and a mesoscale model (KAMM). The mean absolute error comparing the two methods is about...... 10% for two large-scale KAMM domains covering all of Egypt, and typically about 5% for several smaller-scale regional domains. The numerical wind atlas covers all of Egypt, whereas the meteorological stations are concentrated in six regions. The Wind Atlas for Egypt represents a significant step...

  10. Feasibility of Small Wind Turbines in Ontario: Integrating Power Curves with Wind Trends

    OpenAIRE

    Masaō Ashtine; Richard Bello; Kaz Higuchi

    2016-01-01

    Micro-scale/small wind turbines, unlike larger utility-scale turbines, produce electricity at a rate of 300 W to 10 kW at their rated wind speed and are typically below 30 m in hub-height. These wind turbines have much more flexibility in their costs, maintenance and siting, owing to their size, and can provided wind energy in areas much less suited for direct supply to the grid system. In the future under climate change, the energy landscape will likely shift from the present centralized ele...

  11. 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.

  12. Extreme wind estimate for Hornsea wind farm

    DEFF Research Database (Denmark)

    Larsén, Xiaoli Guo

    The purpose of this study is to provide estimation of the 50-year winds of 10 min and 1-s gust value at hub height of 100 m, as well as the design parameter shear exponent for the Hornsea offshore wind farm. The turbulence intensity required for estimating the gust value is estimated using two ap....... The greatest sector-wise extreme winds are from west to northwest. Different data, different periods and different methods have provided a range of values of the 50-year wind and accordingly the gust values, as summarized in Table 15.......The purpose of this study is to provide estimation of the 50-year winds of 10 min and 1-s gust value at hub height of 100 m, as well as the design parameter shear exponent for the Hornsea offshore wind farm. The turbulence intensity required for estimating the gust value is estimated using two...... approaches. One is through the measurements from the wind Doppler lidar, WindCube, which implies serious uncertainty, and the other one is through similarity theory for the atmospheric surface layer where the hub height is likely to belong to during strong storms. The turbulence intensity for storm wind...

  13. 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......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...... 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...

  14. Numerical forecast test on local wind fields at Qinshan Nuclear Power Plant

    International Nuclear Information System (INIS)

    Chen Xiaoqiu

    2005-01-01

    Non-hydrostatic, full compressible atmospheric dynamics model is applied to perform numerical forecast test on local wind fields at Qinshan nuclear power plant, and prognostic data are compared with observed data for wind fields. The results show that the prognostic of wind speeds is better than that of wind directions as compared with observed results. As the whole, the results of prognostic wind field are consistent with meteorological observation data, 54% of wind speeds are within a factor of 1.5, about 61% of the deviation of wind direction within the 1.5 azimuth (≤33.75 degrees) in the first six hours. (authors)

  15. Class generation for numerical wind atlases

    Energy Technology Data Exchange (ETDEWEB)

    Cutler, N.J.; Joergensen, B.H.; Ersboell, B.K.; Badger, J.

    2006-10-15

    A new optimised clustering method is presented for generating wind classes for mesoscale modelling to produce numerical wind atlases. It is compared with the existing method of dividing the data in 12 to 16 sectors, 3 to 7 wind-speed bins and dividing again according to the stability of the atmosphere. Wind atlases are typically produced using many years of on-site wind observations at many locations. Numerical wind atlases are the result of mesoscale model integrations based on synoptic scale wind climates and can be produced in a number of hours of computation. 40 years of twice daily NCEP/NCAR Reanalysis geostrophic wind data (approximately 200 km resolution) are represented in typically around 150 classes, each with a frequency of occurrence. The mean wind-speed and direction in each class is used as input data to force the mesoscale model, which downscales the wind to a 5 km resolution while adapting to the local topography. The purpose of forming classes is to minimise the computational time for the mesoscale model while still representing the synoptic climate features. Only tried briefly in the past, clustering has traits that can be used to improve the existing class generation method by optimising the representation of the data and by automating the procedure more. The Karlsruhe Atmospheric Mesoscale Model (KAMM) is combined with the WAsP analysis to produce numerical wind atlases for two sites, Ireland and Egypt. The model results are compared with wind atlases made from measurements at specific sites. The sources are The New Irish Wind Resource Atlas and the Wind Atlas for the Gulf of Suez. The new clustering method has the ability to include wind-speed, direction and thermal stability from different heights for the classification. It is shown that the clustering method is able to produce results at least as accurate as the existing method for both sites. A refined, general clustering procedure is devised which could improve the results for both sites

  16. Wake Effects on Lifetime Distribution in DFIG-based Wind Farms

    DEFF Research Database (Denmark)

    Tian, Jie; Zhou, Dao; Su, Chi

    2017-01-01

    With the increasing size of the wind farms, the impact of the wake effect on the energy yields and lifetime consumption of wind turbine can no longer be neglected. In this paper, the affecting factors like the wind speed and wind direction are investigated in terms of the single wake and multiple......, and it guides to the optimized control strategies for the balanced reliability....

  17. Mapping Winds over Martian Sand Dunes from Ripples and Digital Terrain Models

    Science.gov (United States)

    Johnson, M. B.; Zimbelman, J. R.

    2015-05-01

    Sand dunes preserve wind flow patterns in their ripple formations. DTMs can be used with wind modeling software to simulate wind speed and direction over these dunes. Results can be compared and together offer a more complete picture of recent wind.

  18. Aspects of Using CFD for Wind Comfort Modeling Around Tall Buildings

    DEFF Research Database (Denmark)

    Rasmussen, Michael R.; Andersen, Lars

    2008-01-01

    The Light*House complex is investigated for uncomfortable wind climate and dangerous winds at pedestrian level. A CFD model is used for simulating the wind effect for 12 different directions and correlated to the wind statistics of a nearby meteorological station. Comparing to practical standards...

  19. The Electrostatic Wind Energy Converter : Electrical performance of a high voltage prototype

    NARCIS (Netherlands)

    Djairam, D.

    2008-01-01

    Wind energy is converted to electrical energy by letting the wind move charged particles against the direction of an electric field. The advantage of this type of conversion is that no rotational movement, which occurs in conventional wind turbines, is required. An electrostatic wind energy

  20. Damping Estimation of a Prototype Bucket Foundation for Offshore Wind Turbines Identified by Full Scale Testing

    DEFF Research Database (Denmark)

    Damgaard, Mads; Ibsen, Lars Bo; Andersen, Lars Vabbersgaard

    2013-01-01

    Wave loading misaligned with wind turbulence often introduces large fatigue loads on offshore wind turbine structures. In this particular case, the structure is sensitive to resonant excitation acting out of the wind direction due to a small aerodynamic damping contribution in the cross-wind dire...