WorldWideScience

Sample records for wind stresses imposed

  1. Individually ventilated cages impose cold stress on laboratory mice: a source of systemic experimental variability.

    Science.gov (United States)

    David, John M; Knowles, Scott; Lamkin, Donald M; Stout, David B

    2013-11-01

    Individual ventilated cages (IVC) are increasing in popularity. Although mice avoid IVC in preference testing, they show no aversion when provided additional nesting material or the cage is not ventilated. Given the high ventilation rate in IVC, we developed 3 hypotheses: that mice housed in IVC experience more cold stress than do mice housed in static cages; that IVC-induced cold stress affects the results of experiments using mice; and that, when provided shelters, mice behaviorally thermoregulate and thereby rescue the cold-stress effects of IVC. To test these hypotheses, we housed mice in IVC, IVC with shelters, and static cages maintained at 20 to 21 °C. We quantified the cold stress of each housing system on mice by assessing nonshivering thermogenesis and brown adipose vacuolation. To test housing effects in a common, murine model of human disease, we implanted mice with subcutaneous epidermoid carcinoma cells and quantified tumor growth, tumor metabolism, and adrenal weight. Mice housed in IVC had histologic signs of cold stress and significantly higher nonshivering thermogenesis, smaller subcutaneous tumors, lower tumor metabolism, and larger adrenal weights than did mice in static cages. Shelters rescued IVC-induced nonshivering thermogenesis, adrenal enlargement, and phenotype-dependent cold-mediated histologic changes in brown adipose tissue and tumor size. IVC impose chronic cold stress on mice, alter experimental results, and are a source of systemic confounders throughout rodent-dependent research. Allowing mice to exhibit behavioral thermoregulation through seeking shelter markedly rescues the experiment-altering effects of housing-imposed cold stress, improves physiologic uniformity, and increases experimental reproducibility across housing systems.

  2. Crop yield response to water stress imposed at different growth stages

    International Nuclear Information System (INIS)

    Iqbal, M.; Mahmood Shah, M.; Wisal, M.

    1995-01-01

    Potato requires sufficient soil moisture and fertilization to produce high yields but the present water resoures are limited compared to the cultivable land, field experiments were conduced from 1991 to 1995 to study relationship between yield and crop water use as a function of water stress imposed at different growth stages. The irrigation treatments involved application of full and stress watering s selectively at four growth stages : Establishment , Flowering Tuber formation and ripening. In full watering, full water requirements of the crop were met, i.e., ET sub a = ET sub m whereas in stress watering about half the amount of full watering was applied, i.e., ET sub a < ET sub m. Changes in moisture content of the soil pre files after irrigation were monitored with the help of neutron moisture probe in order to compute ET sub a by the water balance method. The results obtained showed that the tuber yield was produced by full watering ( T 1) and the lowest by continuous stress watering (T 2). A plot of relative yield against relative evapotranspiration deficit revealed that ripening was the lest sensitive whereas early development followed by flowering the most sensitive growth stage to water stress. The crop water use efficiencies were generally higher in the treatments where a combination of normal and stress watering was applied compared to where all - normal watering s were applied. The traditional irrigation practice resulted in wasteful water application with relatively lower yields, hence the results from this project will have high value for the farming community to get this higher yields with scarce water resources. The studies with labelled fertilizer showed that planting and earthing - up were equally important growth stages of potato for applying fertilizer for its efficient utilization. 3 figs; 25 tabs; 12 refs (Author)

  3. Imposed Environmental Stresses Facilitate Cell-Free Nanoparticle Formation by Deinococcus radiodurans

    Science.gov (United States)

    2017-01-01

    ABSTRACT The biological synthesis of metal nanoparticles has been examined in a wide range of organisms, due to increased interest in green synthesis and environmental remediation applications involving heavy metal ion contamination. Deinococcus radiodurans is particularly attractive for environmental remediation involving metal reduction, due to its high levels of resistance to radiation and other environmental stresses. However, few studies have thoroughly examined the relationships between environmental stresses and the resulting effects on nanoparticle biosynthesis. In this work, we demonstrate cell-free nanoparticle production and study the effects of metal stressor concentrations and identity, temperature, pH, and oxygenation on the production of extracellular silver nanoparticles by D. radiodurans R1. We also report the synthesis of bimetallic silver and gold nanoparticles following the addition of a metal stressor (silver or gold), highlighting how production of these particles is enabled through the application of environmental stresses. Additionally, we found that both the morphology and size of monometallic and bimetallic nanoparticles were dependent on the environmental stresses imposed on the cells. The nanoparticles produced by D. radiodurans exhibited antimicrobial activity comparable to that of pure silver nanoparticles and displayed catalytic activity comparable to that of pure gold nanoparticles. Overall, we demonstrate that biosynthesized nanoparticle properties can be partially controlled through the tuning of applied environmental stresses, and we provide insight into how their application may affect nanoparticle production in D. radiodurans during bioremediation. IMPORTANCE Biosynthetic production of nanoparticles has recently gained prominence as a solution to rising concerns regarding increased bacterial resistance to antibiotics and a desire for environmentally friendly methods of bioremediation and chemical synthesis. To date, a range of

  4. Wind Stress, QuikSCAT SeaWinds, 0.25 degrees, Global, Science Quality, Modulus

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes science quality wind stress data in zonal, meridional, modulus, and wind stress curl sets. This data begins with wind velocity...

  5. Wind Stress, QuikSCAT SeaWinds, 0.25 degrees, Global, Science Quality, Zonal

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes science quality wind stress data in zonal, meridional, modulus, and wind stress curl sets. This data begins with wind velocity...

  6. Wind Stress, QuikSCAT SeaWinds, 0.25 degrees, Global, Science Quality, Meridional

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes science quality wind stress data in zonal, meridional, modulus, and wind stress curl sets. This data begins with wind velocity...

  7. Wind Stress, QuikSCAT SeaWinds, 0.25 degrees, Global, Science Quality, Curl

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes science quality wind stress data in zonal, meridional, modulus, and wind stress curl sets. This data begins with wind velocity...

  8. Southern Ocean carbon-wind stress feedback

    Science.gov (United States)

    Bronselaer, Ben; Zanna, Laure; Munday, David R.; Lowe, Jason

    2018-02-01

    The Southern Ocean is the largest sink of anthropogenic carbon in the present-day climate. Here, Southern Ocean pCO2 and its dependence on wind forcing are investigated using an equilibrium mixed layer carbon budget. This budget is used to derive an expression for Southern Ocean pCO2 sensitivity to wind stress. Southern Ocean pCO2 is found to vary as the square root of area-mean wind stress, arising from the dominance of vertical mixing over other processes such as lateral Ekman transport. The expression for pCO2 is validated using idealised coarse-resolution ocean numerical experiments. Additionally, we show that increased (decreased) stratification through surface warming reduces (increases) the sensitivity of the Southern Ocean pCO2 to wind stress. The scaling is then used to estimate the wind-stress induced changes of atmospheric pCO_2 in CMIP5 models using only a handful of parameters. The scaling is further used to model the anthropogenic carbon sink, showing a long-term reversal of the Southern Ocean sink for large wind stress strength.

  9. Biophysical and biochemical constraints imposed by salt stress:Learning from halophyte

    Directory of Open Access Journals (Sweden)

    Bernardo eDuarte

    2014-12-01

    Full Text Available Soil salinization is one of the most important factors impacting plant productivity. About 3.6 billion of the world’s 5.2 billion ha of agricultural dryland have already suffered erosion, degradation and salinization. Halophytes typically are considered as plants able to complete their life cycle in environments where the salt concentration is 200 mM NaCl or higher. Different strategies are known to overcome salt stress, as adaptation mechanisms from this type of plants. Salinity adjustment is a complex phenomenon characterized by both biochemical and biophysical adaptations. As photosynthesis is a prerequisite for biomass production, halophytes adapted their electronic transduction pathways and the entire energetic metabolism to overcome the salt excess. The maintenance of ionic homeostasis is in the basis of all cellular stress in particular in terms of redox potential and energy transduction. In the present work the biophysical mechanisms underlying energy capture and transduction in halophytes are discussed alongside with their relation to biochemical mechanisms, integrating data from photosystem light harvesting complexes, electronic transport chains to the quinone pools, carbon harvesting and energy dissipation metabolism.

  10. Progressively motile human spermatozoa are well protected against in vitro lipid peroxidation imposed by induced oxidative stress.

    Science.gov (United States)

    Rhemrev, J P; Vermeiden, J P; Haenen, G R; De Bruijne, J J; Rekers-Mombarg, L T; Bast, A

    2001-05-01

    Semen samples of 24 patients were analysed. Volumes were measured and the numbers of progressively motile (PMS), motile (MS) and nonmotile spermatozoa (NMS) were determined. These 24 samples appeared to show a large variation in motility percentages and numbers. Spermatozoa of these semen samples were isolated from the seminal plasma and exposed to induced radical oxygen stress imposed by iron/ascorbate. Lipid peroxidation (LPO) was quantified as thiobarbituric acid reactive material. The contributions of PMS, MS and NMS were also estimated. It was found that the PMS did not contribute to the formation of lipid peroxides. The cellular radical defence system of PMS may offer them adequate protection against the harsh conditions of radical oxygen stress. Stepwise regression analyses showed that only the population of NMS contributed significantly to the explanation of the variance in LPO production (R2 = 0.56, P < 0.001). Pre-existing membrane lipid peroxides were not detected in spermatozoa. It is therefore suggested that LPO takes place only after radical oxygen stress has exhausted the cellular defence system. LPO is not the initial, but one of the later, events leading to the death of spermatozoa. It is concluded that the population of progressively motile spermatozoa in semen samples does not contribute to the production of thiobarbituric acid reactive substances as induced by in vitro radical oxygen stress.

  11. A Root-Colonizing Pseudomonad Lessens Stress Responses in Wheat Imposed by CuO Nanoparticles

    Science.gov (United States)

    Wright, Melanie; Adams, Joshua; Yang, Kwang; McManus, Paul; Jacobson, Astrid; Gade, Aniket; McLean, Joan; Britt, David; Anderson, Anne

    2016-01-01

    Nanoparticle (NPs) containing essential metals are being considered in formulations of fertilizers to boost plant nutrition in soils with low metal bioavailability. This paper addresses whether colonization of wheat roots by the bacterium, Pseudomonas chlororaphis O6 (PcO6), protected roots from the reduced elongation caused by CuO NPs. There was a trend for slightly elongated roots when seedlings with roots colonized by PcO6 were grown with CuO NPs; the density of bacterial cells on the root surface was not altered by the NPs. Accumulations of reactive oxygen species in the plant root cells caused by CuO NPs were little affected by root colonization. However, bacterial colonization did reduce the extent of expression of an array of genes associated with plant responses to stress induced by root exposure to CuO NPs. PcO6 colonization also reduced the levels of two important chelators of Cu ions, citric and malic acids, in the rhizosphere solution; presumably because these acids were used as nutrients for bacterial growth. There was a trend for lower levels of soluble Cu in the rhizosphere solution and reduced Cu loads in the true leaves with PcO6 colonization. These studies indicate that root colonization by bacterial cells modulates plant responses to contact with CuO NPs. PMID:27776146

  12. A Root-Colonizing Pseudomonad Lessens Stress Responses in Wheat Imposed by CuO Nanoparticles.

    Directory of Open Access Journals (Sweden)

    Melanie Wright

    Full Text Available Nanoparticle (NPs containing essential metals are being considered in formulations of fertilizers to boost plant nutrition in soils with low metal bioavailability. This paper addresses whether colonization of wheat roots by the bacterium, Pseudomonas chlororaphis O6 (PcO6, protected roots from the reduced elongation caused by CuO NPs. There was a trend for slightly elongated roots when seedlings with roots colonized by PcO6 were grown with CuO NPs; the density of bacterial cells on the root surface was not altered by the NPs. Accumulations of reactive oxygen species in the plant root cells caused by CuO NPs were little affected by root colonization. However, bacterial colonization did reduce the extent of expression of an array of genes associated with plant responses to stress induced by root exposure to CuO NPs. PcO6 colonization also reduced the levels of two important chelators of Cu ions, citric and malic acids, in the rhizosphere solution; presumably because these acids were used as nutrients for bacterial growth. There was a trend for lower levels of soluble Cu in the rhizosphere solution and reduced Cu loads in the true leaves with PcO6 colonization. These studies indicate that root colonization by bacterial cells modulates plant responses to contact with CuO NPs.

  13. Enhancement of wind stress evaluation method under storm conditions

    Science.gov (United States)

    Chen, Yingjian; Yu, Xiping

    2016-12-01

    Wind stress is an important driving force for many meteorological and oceanographical processes. However, most of the existing methods for evaluation of the wind stress, including various bulk formulas in terms of the wind speed at a given height and formulas relating the roughness height of the sea surface with wind conditions, predict an ever-increasing tendency of the wind stress coefficient as the wind speed increases, which is inconsistent with the field observations under storm conditions. The wave boundary layer model, which is based on the momentum and energy conservation, has the advantage to take into account the physical details of the air-sea interaction process, but is still invalid under storm conditions without a modification. By including the energy dissipation due to the presence of sea spray, which is speculated to be an important aspect of the air-sea interaction under storm conditions, the wave boundary layer model is improved in this study. The improved model is employed to estimate the wind stress caused by an idealized tropical cyclone motion. The computational results show that the wind stress coefficient reaches its maximal value at a wind speed of about 40 m/s and decreases as the wind speed further increases. This is in fairly good agreement with the field data.

  14. Investigating the effect of tractive parameters on imposed vertical stresses under driving wheel using a soil bin test rig facility

    Directory of Open Access Journals (Sweden)

    H Taghavifar

    2015-09-01

    traction force. Furthermore, it was deduced that the increase in depth leads to a reduction of soil vertical stresses. Conclusions: The present study is aimed at investigating the effect of net traction force on the imposed vertical stress under the 220/65R21 driving wheel. Hence, velocity at three levels (i.e. 0.8, 1, 1.2 m s-1, wheel load at three levels (i.e. 2, 3, and 4 kN and slippage at three levels (i.e. 8, 12, and 15% were considered to obtain traction force and soil vertical stress at three depths of 0.1, 0.15 and 0.2 m. Experiments were carried out in the complete randomized block design with three replicates on clay loam soil at 12% moisture content. The vertical stress was measured using a manufactured soil stress transducer where the net traction was measured using four horizontally installed load cells between the tester rig and the carriage. A correlation was developed between soil stress and traction force. The results revealed that vertical stress increases with respect to increase of wheel load and slippage, whereas vertical stress decreases by increase in depth and velocity. Additionally, it was found that wheel load and slippage bring about increased traction force while velocity has no significant effect on traction force at 1% significance level. Finally, it was deduced that an increase of traction force results in an increase of vertical stress transmission.

  15. Relationships between climate at origin and seedling traits in eight Panafrican provenances of Vitellaria paradoxa C.F. Gaertn. under imposed drought stress

    DEFF Research Database (Denmark)

    Bayala, J.; Sanon, Z.; Bazié, P.

    2018-01-01

    The morphological responses of seedlings of eight African provenances of Vitellaria paradoxa (Shea tree or Karité) to imposed draught stress were compared under nursery experimental conditions. The potted seedlings were subjected to three different watering regimes (87 days after sowing): no water...... stress (100% of the field capacity, C), moderate water stress (75% of C) and severe water stress (50% of C). Before the application of the stress, we observed genotypical differences in the morphological variables at the scale of leaves and of above-ground parts. The six-month water stress affected...

  16. Vulnerability imposed by diet and brain trauma for anxiety-like phenotype: implications for post-traumatic stress disorders.

    Directory of Open Access Journals (Sweden)

    Ethika Tyagi

    Full Text Available Mild traumatic brain injury (mTBI, cerebral concussion is a risk factor for the development of psychiatric illness such as posttraumatic stress disorder (PTSD. We sought to evaluate how omega-3 fatty acids during brain maturation can influence challenges incurred during adulthood (transitioning to unhealthy diet and mTBI and predispose the brain to a PTSD-like pathobiology. Rats exposed to diets enriched or deficient in omega-3 fatty acids (n-3 during their brain maturation period, were transitioned to a western diet (WD when becoming adult and then subjected to mTBI. TBI resulted in an increase in anxiety-like behavior and its molecular counterpart NPY1R, a hallmark of PTSD, but these effects were more pronounced in the animals exposed to n-3 deficient diet and switched to WD. The n-3 deficiency followed by WD disrupted BDNF signaling and the activation of elements of BDNF signaling pathway (TrkB, CaMKII, Akt and CREB in frontal cortex. TBI worsened these effects and more prominently in combination with the n-3 deficiency condition. Moreover, the n-3 deficiency primed the immune system to the challenges imposed by the WD and brain trauma as evidenced by results showing that the WD or mTBI affected brain IL1β levels and peripheral Th17 and Treg subsets only in animals previously conditioned to the n-3 deficient diet. These results provide novel evidence for the capacity of maladaptive dietary habits to lower the threshold for neurological disorders in response to challenges.

  17. Vulnerability imposed by diet and brain trauma for anxiety-like phenotype: implications for post-traumatic stress disorders.

    Science.gov (United States)

    Tyagi, Ethika; Agrawal, Rahul; Zhuang, Yumei; Abad, Catalina; Waschek, James A; Gomez-Pinilla, Fernando

    2013-01-01

    Mild traumatic brain injury (mTBI, cerebral concussion) is a risk factor for the development of psychiatric illness such as posttraumatic stress disorder (PTSD). We sought to evaluate how omega-3 fatty acids during brain maturation can influence challenges incurred during adulthood (transitioning to unhealthy diet and mTBI) and predispose the brain to a PTSD-like pathobiology. Rats exposed to diets enriched or deficient in omega-3 fatty acids (n-3) during their brain maturation period, were transitioned to a western diet (WD) when becoming adult and then subjected to mTBI. TBI resulted in an increase in anxiety-like behavior and its molecular counterpart NPY1R, a hallmark of PTSD, but these effects were more pronounced in the animals exposed to n-3 deficient diet and switched to WD. The n-3 deficiency followed by WD disrupted BDNF signaling and the activation of elements of BDNF signaling pathway (TrkB, CaMKII, Akt and CREB) in frontal cortex. TBI worsened these effects and more prominently in combination with the n-3 deficiency condition. Moreover, the n-3 deficiency primed the immune system to the challenges imposed by the WD and brain trauma as evidenced by results showing that the WD or mTBI affected brain IL1β levels and peripheral Th17 and Treg subsets only in animals previously conditioned to the n-3 deficient diet. These results provide novel evidence for the capacity of maladaptive dietary habits to lower the threshold for neurological disorders in response to challenges.

  18. Wind Stress, METOP ASCAT, 0.25 degrees, Global, Near Real Time, Curl

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes near real time wind stress data in zonal, meridional, modulus, and wind stress curl sets. This data begins with wind velocity...

  19. Wind Stress, METOP ASCAT, 0.25 degrees, Global, Near Real Time, Meridional

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes near real time wind stress data in zonal, meridional, modulus, and wind stress curl sets. This data begins with wind velocity...

  20. Wind Stress, METOP ASCAT, 0.25 degrees, Global, Near Real Time, Modulus

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes near real time wind stress data in zonal, meridional, modulus, and wind stress curl sets. This data begins with wind velocity...

  1. Wind Stress, METOP ASCAT, 0.25 degrees, Global, Near Real Time, Zonal

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes near real time wind stress data in zonal, meridional, modulus, and wind stress curl sets. This data begins with wind velocity...

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

    International Nuclear Information System (INIS)

    Ligotke, M.W.

    1993-02-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Ligotke, M.W.

    1993-02-01

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

  4. The influence of ventilation tube design on the magnitude of stress imposed at the implant/tympanic membrane interface.

    LENUS (Irish Health Repository)

    Vard, John P

    2008-03-01

    The design of ventilation tubes or grommets is thought to have a considerable influence on their performance. A computational model (finite element method) was used to investigate the significance of four design parameters of a commonly used design of ventilation tube. The design parameters were: the length of the shaft, the diameter of the flanges, the thickness of the flanges, and the material type. A statistical analysis technique, known as a factorial analysis of variance, was used to examine the importance of the four design parameters on the dynamical behaviour of the middle ear with the implant in situ and on the magnitude of stress induced at the implant\\/tympanic membrane interface. We predicted that the ventilation tube alters the frequency response of the middle ear; specifically the shaft length and the thickness of the flanges were found to have a significant effect upon the vibratory pattern at the umbo. A reduced length of tube and an increased size of flange were also found to be significant for minimising membrane stress (both with P<0.001). Thus, design parameters of critical influence on optimising performance were identified.

  5. Wind stress, curl and vertical velocity in the Bay of Bengal during southwest monsoon, 1984

    Digital Repository Service at National Institute of Oceanography (India)

    Babu, M.T.; Heblekar, A.K.; Murty, C.S.

    Wind distribution observed during southwest monsoon of 1984 has used to derive the mean wind stress for the season at every 1 degree square grid and curl over the Bay of Bengal. Two regions of maximum wind stress are present over the Bay of Bengal...

  6. Blended 6-Hourly Sea Surface Wind Vectors and Wind Stress on a Global 0.25 Degree Grid (1987-2011)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Blended Global Sea Surface Winds products contain ocean surface wind vectors and wind stress on a global 0.25 degree grid, in multiple time resolutions of...

  7. Wind stress over the Arabian Sea from ship reports and Seasat scatterometer data

    Science.gov (United States)

    Perigaud, C.; Minster, J. F.; Delecluse, P.

    1989-01-01

    Seasat scatterometer data over the Arabian Sea are used to build wind-stress fields during July and August 1978. They are first compared with 3-day wind analyses from ship data along the Somali coast. Seasat scatterometer specifications of 2-m/s and 20-deg accuracy are fulfilled in almost all cases. The exceptions are for winds stronger than 14 m/s, which are underestimated by the scatterometer by 15 percent. Wind stress is derived from these wind data using a bulk formula with a drag coefficient depending on the wind intensity. A successive-correction objective analysis is used to build the wind-stress field over the Arabian Sea with 2 x 2-deg and 6-day resolution. The final wind-stress fields are not significantly dependent on the objective analysis because of the dense coverage of the scatterometer. The combination of scatterometer and coastal ship data gives the best coverage to resolve monsoon wind structures even close to the coast. The final wind stress fields show wind features consistent with other monthly mean wind stress field. However, a high variability is observed on the 6-day time scale.

  8. ZnO nanoparticles impose a panmetabolic toxic effect along with strong necrosis, inducing activation of the envelope stress response in Salmonella enterica serovar Enteritidis.

    Science.gov (United States)

    Vidovic, Sinisa; Elder, Jeff; Medihala, Prabhakara; Lawrence, John R; Predicala, Bernardo; Zhang, Haixia; Korber, Darren R

    2015-01-01

    In this study, we tested the antimicrobial activity of three metal nanoparticles (NPs), ZnO, MgO, and CaO NPs, against Salmonella enterica serovar Enteritidis in liquid medium and on solid surfaces. Out of the three tested metal NPs, ZnO NPs exhibited the most significant antimicrobial effect both in liquid medium and when embedded on solid surfaces. Therefore, we focused on revealing the mechanisms of surface-associated ZnO biocidal activity. Using the global proteome approach, we report that a great majority (79%) of the altered proteins in biofilms formed by Salmonella enterica serovar Enteritidis were downregulated, whereas a much smaller fraction (21%) of proteins were upregulated. Intriguingly, all downregulated proteins were enzymes involved in a wide range of the central metabolic pathways, including translation; amino acid biosynthetic pathways; nucleobase, nucleoside, and nucleotide biosynthetic processes; ATP synthesis-coupled proton transport; the pentose phosphate shunt; and carboxylic acid metabolic processes, indicating that ZnO NPs exert a panmetabolic toxic effect on this prokaryotic organism. In addition to their panmetabolic toxicity, ZnO NPs induced profound changes in cell envelope morphology, imposing additional necrotic effects and triggering the envelope stress response of Salmonella serovar Enteritidis. The envelope stress response effect activated periplasmic chaperones and proteases, transenvelope complexes, and regulators, thereby facilitating protection of this prokaryotic organism against ZnO NPs. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  9. TropFlux wind stresses over the tropical oceans: Evaluation and comparison with other products

    Digital Repository Service at National Institute of Oceanography (India)

    PraveenKumar, B.; Vialard, J.; Lengaigne, M.; Murty, V.S.N.; McPhaden, M.J.; Cronin, M.F.; Pinsard, F.; Reddy, K.G.

    the hourly values. Note that, we neglected surface currents (which are not always available) while computing wind stresses at these moorings. 3. The TropFlux wind stress product In this section, we first present the methodology for computing Trop... onset. Hence, we recommend the use of TropFlux for studies of equatorial ocean dynamics. Key words: TropFlux, tropics, air-sea momentum fluxes, wind stress products validation. 3 1. Introduction The tropics are home to many climatically relevant...

  10. Wind stress and heat fluxes over a Brazilian Coastal Upwelling

    Science.gov (United States)

    Dourado, Marcelo; Candella, Rogério

    2017-04-01

    Coastal upwelling zones have been intensively studied in the last decades especially due to their importance to the biological cycle. The coastal upwelling system of the Cabo Frio region (east coast of the Rio de Janeiro state, Brazil) keeps the surface water cold during most part of the year, what induces a stable atmospheric boundary layer associated to northeast winds. The main goal of this study is to investigate the wind stress and heat fluxes exchanges between the ocean and the atmosphere in that area. For this purpose, a set of hourly data meteorological and oceanographic data collected by a Wavescan metocean buoy anchored at 23o59S; 42oW, were used, as well as solar radiation and relative humidity from a terrestrial meteorological station from the Instituto Nacional de Meteorologia (InMet). COARE 3.0 algorithm was used to calculate the latent and sensible heat fluxes. In this discussion, positive values represent fluxes towards the ocean. The average net heat flux over our study period is 88 W m-2. The reduction of the net heat flux is due to the increase of the ocean latent heat loss, although a reduction in incoming shortwave radiation and an increase in ocean long wave cooling also contributes. The latent heat is 20 times larger than the sensible heat flux, but the mean value of the latent heat flux, 62 W m-2, is half the typical value found in open ocean. The temporal variability of both sensible and latent heat fluxes reflects their dependence on wind speed and air-sea temperature differences. When upwelling events, here periods when diurnal SST is lower than 18oC, are compared with undisturbed (without upwelling) events, it can be noted the sensible heat fluxes are positives and 10 times greater in magnitude. This is related to an increment, during these upwelling events, of the air-sea temperature difference and an increasing of the wind speed. The cold waters of the upwelling increase the air-sea temperature gradient and, also, the horizontal land

  11. Generation of Random Wind Speed Profiles for Evaluation of Stress in WT Power Converters

    DEFF Research Database (Denmark)

    Pigazo, Alberto; Qin, Zian; Liserre, Marco

    2013-01-01

    Wind turbines are subjected to wind speed variations that cause a power profile that will stress the overall system. This stress is tranfered to the power converter, resulting in temperature variations of the power devices and, hence, causing the reduction of the lifetime. The lifetime expectation...... changes depending on the real wind speed once the wind turbine is operating. Usually, the real wind speed profiles are employed to evaluate this stress but they do not consider all possible operation conditions and require intensive computations. To solve these issues, this paper proposes the generation...... of random wind speed profiles, based on the measured ones, in order to evaluate the thermal stress of the power devices based on a simplified statistical approach....

  12. Swell impact on wind stress and atmospheric mixing in a regional coupled atmosphere-wave model

    DEFF Research Database (Denmark)

    Wu, Lichuan; Rutgersson, Anna; Sahlée, Erik

    2016-01-01

    Over the ocean, the atmospheric turbulence can be significantly affected by swell waves. Change in the atmospheric turbulence affects the wind stress and atmospheric mixing over swell waves. In this study, the influence of swell on atmospheric mixing and wind stress is introduced into an atmosphere......-neutral and unstable stratification conditions is introduced by changing the roughness length. Five year simulation results indicate that adding the swell influence on atmospheric mixing has limited influence, only slightly increasing the near-surface wind speed; in contrast, adding the swell influence on wind stress....... The influence varies with wave characteristics for different sea basins. Swell occurs infrequently in the studied area, and one could expect more influence in high-swell-frequency areas (i.e., low-latitude ocean). We conclude that the influence of swell on atmospheric mixing and wind stress should be considered...

  13. Stress analysis of composite wind turbine blade by finite element method

    Science.gov (United States)

    Yeh, Meng-Kao; Wang, Chen-Hsu

    2017-10-01

    In this study, the finite element analysis software ANSYS was used to analyze the composite wind turbine blade. The wind turbine blade model used is adopted from the 5 MW model of US National Renewable Energy Laboratory (NREL). The wind turbine blade is a sandwich structure, comprising outermost carbon fiber cloth/epoxy composites, the inner glass fiber/vinylester layers, and PVC foam core, together with stiffeners. The wind pressure is converted into the load on the blade structure. The stress distribution and deformation of wind turbine blade were obtained by considering different pitch angles and at different angular positions. The Tsai-Hill criterion was used to determine the failure of wind turbine blade. The results show that at the 0° pitch angle, the wind turbine blade is subjected to the largest combined load and therefore the stress is the largest; with the increasing pitch angle, the load gradually decreases and the stress is also smaller. The stress and displacement are the greatest when the wind blade is located at 120° angular position from its highest vertex.

  14. TAO/TRITON, RAMA, and PIRATA Buoys, Monthly, 1989-present, Wind Stress

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has monthly Wind Stress data from the TAO/TRITON (Pacific Ocean, https://www.pmel.noaa.gov/gtmba/ ), RAMA (Indian Ocean,...

  15. TAO/TRITON, RAMA, and PIRATA Buoys, 5-Day, 1989-present, Wind Stress

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has 5-day Wind Stress data from the TAO/TRITON (Pacific Ocean, https://www.pmel.noaa.gov/gtmba/ ), RAMA (Indian Ocean,...

  16. TAO/TRITON, RAMA, and PIRATA Buoys, Daily, 1989-present, Wind Stress

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has daily Wind Stress data from the TAO/TRITON (Pacific Ocean, https://www.pmel.noaa.gov/gtmba/ ), RAMA (Indian Ocean,...

  17. Contributions of soluble carbohydrates to the osmotic adjustment in the C4 grass Setaria sphacelata: a comparison between rapidly and slowly imposed water stress.

    Science.gov (United States)

    da Silva, Jorge Marques; Arrabaça, Maria Celeste

    2004-05-01

    Photosynthetic carbohydrate content in Setaria sphacelata var. splendida under rapidly and slowly induced water deficit and its contribution to osmotic adjustment were studied. In short-term stress experiments, a decrease in the total content of sucrose (Su) and starch (St) was observed in leaf discs submitted to stress. An increase in the ratio between free hexoses and sucrose was found in stressed leaves, but no significant differences were found in the amount of free hexoses nor in the ratio between soluble and insoluble sugars. In long-term stress experiments, a higher amount of soluble sugars and a lower amount of starch were found in stressed leaves, when compared to the control. The ratios of free hexoses to sucrose and of soluble to insoluble sugars were also higher in stressed leaves. The contribution of the accumulation of soluble sugars to osmotic adjustment was absent in rapidly stressed leaves and was of minor importance in slowly stressed leaves.

  18. A Non-Linear Upscaling Approach for Wind Turbines Blades Based on Stresses

    NARCIS (Netherlands)

    Castillo Capponi, P.; Van Bussel, G.J.W.; Ashuri, T.; Kallesoe, B.

    2011-01-01

    The linear scaling laws for upscaling wind turbine blades show a linear increase of stresses due to the weight. However, the stresses should remain the same for a suitable design. Application of linear scaling laws may lead to an upscaled blade that may not be any more a feasible design. In this

  19. Acceptance and stress effects of aircraft obstruction markings of wind turbines

    International Nuclear Information System (INIS)

    Pohl, Johannes; Hübner, Gundula; Mohs, Anja

    2012-01-01

    A dominant resistance factor against wind power projects seems to be their visual impact on the landscape. In addition stress effects from aircraft obstruction markings are an emerging topic related to acceptance. As the height of wind turbines increases, so does the number of mandatory obstruction markings. Recently, obstruction markings have caused a growing number of complaints from residents. Whether obstruction markings indeed cause stress or even substantial annoyance remains an open question. To analyse the stress impact of obstruction markings, we used environmental and stress psychology methodologies. Residents (N=420) with direct sight of turbines at 13 wind farms participated in a questionnaire survey. Evidence of substantial annoyance caused by obstruction markings was not found. However, residents exposed to xenon lights reported more intense and multifaceted stress responses than exposed to LED or colour markings on blades. Moreover, xenon lights negatively affected the general acceptance of wind energy. Additionally, synchronised navigation lights were found to be less annoying than non-synchronised lights under certain weather conditions. Markings with light intensity adjustment proved to be advantageous. To reduce stress and increase social acceptance of wind power, xenon lights should be abandoned, navigation lights synchronised, and light intensity adjustment applied. - Research highlights: ► Wind turbine obstruction markings influence the social acceptance of wind energy. ► Residents exposed to xenon lights reported more intense stress responses than exposed to LED or colour markings. ► Synchronised lights were found to be less annoying under certain weather conditions. ► Markings with light intensity adjustment proved to be advantageous. ► Evidence of substantial annoyance caused by obstruction markings was not found.

  20. Numerical model for wind-driven circulation in the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Bahulayan, N.; Varadachari, V.V.R.

    experiments have shown that when a uniform wind stress in suddenly imposed over the sea surface, a steady circulation is generated after 50 h of numerical integration of model equations. The sensitivity of this model to bathymetry and coastal configuration...

  1. An Exploration of Wind Stress Calculation Techniques in Hurricane Storm Surge Modeling

    Directory of Open Access Journals (Sweden)

    Kyra M. Bryant

    2016-09-01

    Full Text Available As hurricanes continue to threaten coastal communities, accurate storm surge forecasting remains a global priority. Achieving a reliable storm surge prediction necessitates accurate hurricane intensity and wind field information. The wind field must be converted to wind stress, which represents the air-sea momentum flux component required in storm surge and other oceanic models. This conversion requires a multiplicative drag coefficient for the air density and wind speed to represent the air-sea momentum exchange at a given location. Air density is a known parameter and wind speed is a forecasted variable, whereas the drag coefficient is calculated using an empirical correlation. The correlation’s accuracy has brewed a controversy of its own for more than half a century. This review paper examines the lineage of drag coefficient correlations and their acceptance among scientists.

  2. Test Results of a Nb3Sn Wind/React ''Stress-Managed'' Block Dipole

    International Nuclear Information System (INIS)

    McInturff, A.; Bish, P.; Blackburn, R.; Diaczenko, N.; Elliott, T.; Hafalia Jr., R.; Henchel, W.; Jaisle, A.; Lau, W.; Lietzke, A.; McIntyre, P.; Noyes, P.; Nyman, M.; Sattarov, A.; Sattarov, A.

    2006-01-01

    A second phase of a highfield dipole technology development has been tested. A Nb3Sn block-coil model dipole was fabricated, using magnetic mirror geometry and wind/react coil technology. The primary objective of this phase was to make a first experimental test of the stress-management strategy pioneered at Texas A and M. In this strategy a high-strength support matrix is integrated with the windings to intercept Lorentz stress from the inner winding so that it does not accumulate in the outer winding. The magnet attained a field that was consistent with short sample limit on the first quench; there was no training. The decoupling of Lorentz stress between inner and outer windings was validated. In ramp rate studies the magnet exhibited a remarkable robustness in rapid ramping operation. It reached 85 percent of short sample(ss) current even while ramping 2-3 T/s. This robustness is attributed to the orientation of the Rutherford cables parallel to the field in the windings, instead of the transverse orientation that characterizes common dipole designs. Test results are presented and the next development phase plans are discussed

  3. WIND TURBINES CAUSE CHRONIC STRESS IN BADGERS (MELES MELES) IN GREAT BRITAIN.

    Science.gov (United States)

    Agnew, Roseanna C N; Smith, Valerie J; Fowkes, Robert C

    2016-07-01

    A paucity of data exists with which to assess the effects of wind turbines noise on terrestrial wildlife, despite growing concern about the impact of infrasound from wind farms on human health and well-being. In 2013, we assessed whether the presence of turbines in Great Britain impacted the stress levels of badgers ( Meles meles ) in nearby setts. Hair cortisol levels were used to determine if the badgers were physiologically stressed. Hair of badgers living 10 km from a wind farm. This demonstrates that affected badgers suffer from enhanced hypothalamo-pituitary-adrenal activity and are physiologically stressed. No differences were found between the cortisol levels of badgers living near wind farms operational since 2009 and 2012, indicating that the animals do not become habituated to turbine disturbance. Cortisol levels in the affected badgers did not vary in relation to the distance from turbines within 1 km, wind farm annual power output, or number of turbines. We suggest that the higher cortisol levels in affected badgers is caused by the turbines' sound and that these high levels may affect badgers' immune systems, which could result in increased risk of infection and disease in the badger population.

  4. Scales of North Atlantic wind stress curl determined from the comprehensive ocean-atmosphere data set

    Science.gov (United States)

    Ehret, Laura L.; O'Brien, James J.

    1989-01-01

    Nineteen years of wind data over the North Atlantic are used to calculate a field of wind stress curl. An empirical orthogonal function (EOF) analysis is performed on this field, resulting in spatial patterns of wind stress curl and associated time series. A Monte Carlo technique is used to establish the statistical significance of each spatial pattern, and the associated time series are spectrally analyzed. The first four statistically significant EOF modes represent more than 50 percent of the curl variance, and the spatial patterns of curl associated with these modes exhibit the major elements of North Atlantic climatology. Most of the time series spectral variance is contained in annual and semiannual frequencies. The features observed include the individual annual variation of the subtropical high and the subpolar low, the annual oscillation of intensity between pressure centers, the influence of localized strong SST gradients and associated cyclogenesis regions, and the constant nature of the trades.

  5. 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.

  6. Impacts of Wind Stress Changes on the Global Heat Transport, Baroclinic Instability, and the Thermohaline Circulation

    Directory of Open Access Journals (Sweden)

    Jeferson Prietsch Machado

    2016-01-01

    Full Text Available The wind stress is a measure of momentum transfer due to the relative motion between the atmosphere and the ocean. This study aims to investigate the anomalous pattern of atmospheric and oceanic circulations due to 50% increase in the wind stress over the equatorial region and the Southern Ocean. In this paper we use a coupled climate model of intermediate complexity (SPEEDO. The results show that the intensification of equatorial wind stress causes a decrease in sea surface temperature in the tropical region due to increased upwelling and evaporative cooling. On the other hand, the intensification of wind stress over the Southern Ocean induces a regional increase in the air and sea surface temperatures which in turn leads to a reduction in Antarctic sea ice thickness. This occurs in association with changes in the global thermohaline circulation strengthening the rate of Antarctic Bottom Water formation and a weakening of the North Atlantic Deep Water. Moreover, changes in the Southern Hemisphere thermal gradient lead to modified atmospheric and oceanic heat transports reducing the storm tracks and baroclinic activity.

  7. Monthly mean wind stress along the coast of the north Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Shetye, S.R.; Shenoi, S.S.C.; Antony, M.K.; Krishnakumar, V.

    Monthly-mean wind stress and its longshore and offshore components have been computed using the bulk aerodynamic method for each of a string of 36 two-degree-latitude by two-degree-longitude squares along the coast of the north Indian Ocean...

  8. Global Gene-expression Analysis of the Response of Salmonella Enteritidis to Egg White Exposure Reveals Multiple Egg White-imposed Stress Responses

    Directory of Open Access Journals (Sweden)

    Florence Baron

    2017-05-01

    Full Text Available Chicken egg white protects the embryo from bacterial invaders by presenting an assortment of antagonistic activities that combine together to both kill and inhibit growth. The key features of the egg white anti-bacterial system are iron restriction, high pH, antibacterial peptides and proteins, and viscosity. Salmonella enterica serovar Enteritidis is the major pathogen responsible for egg-borne infection in humans, which is partly explained by its exceptional capacity for survival under the harsh conditions encountered within egg white. However, at temperatures up to 42°C, egg white exerts a much stronger bactericidal effect on S. Enteritidis than at lower temperatures, although the mechanism of egg white-induced killing is only partly understood. Here, for the first time, the impact of exposure of S. Enteritidis to egg white under bactericidal conditions (45°C is explored by global-expression analysis. A large-scale (18.7% of genome shift in transcription is revealed suggesting major changes in specific aspects of S. Enteritidis physiology: induction of egg white related stress-responses (envelope damage, exposure to heat and alkalinity, and translation shutdown; shift in energy metabolism from respiration to fermentation; and enhanced micronutrient provision (due to iron and biotin restriction. Little evidence of DNA damage or redox stress was obtained. Instead, data are consistent with envelope damage resulting in cell death by lysis. A surprise was the high degree of induction of hexonate/hexuronate utilization genes, despite no evidence indicating the presence of these substrates in egg white.

  9. Global Gene-expression Analysis of the Response ofSalmonellaEnteritidis to Egg White Exposure Reveals Multiple Egg White-imposed Stress Responses.

    Science.gov (United States)

    Baron, Florence; Bonnassie, Sylvie; Alabdeh, Mariah; Cochet, Marie-Françoise; Nau, Françoise; Guérin-Dubiard, Catherine; Gautier, Michel; Andrews, Simon C; Jan, Sophie

    2017-01-01

    Chicken egg white protects the embryo from bacterial invaders by presenting an assortment of antagonistic activities that combine together to both kill and inhibit growth. The key features of the egg white anti-bacterial system are iron restriction, high pH, antibacterial peptides and proteins, and viscosity. Salmonella enterica serovar Enteritidis is the major pathogen responsible for egg-borne infection in humans, which is partly explained by its exceptional capacity for survival under the harsh conditions encountered within egg white. However, at temperatures up to 42°C, egg white exerts a much stronger bactericidal effect on S . Enteritidis than at lower temperatures, although the mechanism of egg white-induced killing is only partly understood. Here, for the first time, the impact of exposure of S . Enteritidis to egg white under bactericidal conditions (45°C) is explored by global-expression analysis. A large-scale (18.7% of genome) shift in transcription is revealed suggesting major changes in specific aspects of S . Enteritidis physiology: induction of egg white related stress-responses (envelope damage, exposure to heat and alkalinity, and translation shutdown); shift in energy metabolism from respiration to fermentation; and enhanced micronutrient provision (due to iron and biotin restriction). Little evidence of DNA damage or redox stress was obtained. Instead, data are consistent with envelope damage resulting in cell death by lysis. A surprise was the high degree of induction of hexonate/hexuronate utilization genes, despite no evidence indicating the presence of these substrates in egg white.

  10. Analysis of Mechanical Stresses Due to Voltage Dips in Fixed-Speed Wind Turbines

    DEFF Research Database (Denmark)

    Veluri, Badrinath; Santos-Martin, David; Jensen, Henrik Myhre

    2011-01-01

    stresses transients that may have a detrimental effect on the fatigue life of drivetrain system due to voltage dips. A rainflow cycle counting method for the stress history during the voltage dip event, analyses mean and amplitudes of the counted cycles, their occurrence moment and time of duration.......Voltage dips due to electrical grid faults generate transients of the generator electromagnetic torque which result in significant high stresses and noticeable vibrations for the wind turbine mechanical system. These events may also have a detrimental effect on the fatigue life of important...

  11. Legal theology in imposed constitutionalism

    DEFF Research Database (Denmark)

    Abat Ninet, Antoni

    2018-01-01

    The focus of this paper is the question of legitimacy, and how can we consider legitimate an imposed constitution and the subsequent constitutional principles, practices and values that go hand-in-hand with the legal and political acculturation. Constitutional texts around the world are good...... examples of transposition and complicity of theological and juridical thoughts. For the purpose of this paper, imposed constitutions are political and legal norms of a state enacted and enforced without the free and full agreement of the Demos. Legal theology implies the application of religious phenomena......, theories and concepts to achieve undisputed legal legitimacy. Imposed constitutions as rules imposed for salvation for those “Platonic Philosophes” who have seen the “light”, that known the episteme are paramount examples of legal and political theology. The paper has two main sections. The first one...

  12. Intercomparison of the Charnock and COARE bulk wind stress formulations for coastal ocean modelling

    Directory of Open Access Journals (Sweden)

    J. M. Brown

    2013-08-01

    Full Text Available The accurate parameterisation of momentum and heat transfer across the air–sea interface is vital for realistic simulation of the atmosphere–ocean system. In most modelling applications accurate representation of the wind stress is required to numerically reproduce surge, coastal ocean circulation, surface waves, turbulence and mixing. Different formulations can be implemented and impact the accuracy of the instantaneous and long-term residual circulation, the surface mixed layer, and the generation of wave-surge conditions. This, in turn, affects predictions of storm impact, sediment pathways, and coastal resilience to climate change. The specific numerical formulation needs careful selection to ensure the accuracy of the simulation. Two wind stress parameterisations widely used in the ocean circulation and the storm surge communities respectively are studied with focus on an application to the NW region of the UK. Model–observation validation is performed at two nearshore and one estuarine ADCP (acoustic Doppler current profiler stations in Liverpool Bay, a hypertidal region of freshwater influence (ROFI with vast intertidal areas. The period of study covers both calm and extreme conditions to test the robustness of the 10 m wind stress component of the Coupled Ocean–Atmosphere Response Experiment (COARE bulk formulae and the standard Charnock relation. In this coastal application a realistic barotropic–baroclinic simulation of the circulation and surge elevation is set-up, demonstrating greater accuracy occurs when using the Charnock relation, with a constant Charnock coefficient of 0.0185, for surface wind stress during this one month period.

  13. Adding insult to injury: The development of psychosocial stress in Ontario wind turbine communities.

    Science.gov (United States)

    Walker, Chad; Baxter, Jamie; Ouellette, Danielle

    2015-05-01

    Though historically dismissed as not-in-my-backyard (NIMBY) attitudes, reports of psychosocial stress linked to wind energy developments have emerged in Ontario, Canada. While the debate and rhetoric intensify concerning whether wind turbines 'actually' cause 'health' effects, less sincere attention has been given to the lived experience and mental well-being of those near turbines. Drawing on theories of environmental stress, this grounded theory, mixed-method (n = 26 interviews; n = 152 questionnaires) study of two communities in 2011 and 2012 traces how and why some wind turbine community residents suffer substantial changes to quality of life, develop negative perceptions of 'the other' and in some cases, experience intra-community conflict. Policy-related forces, along with existing community relationships may help explain much of these differences between communities. We suggest a move beyond debating simply whether or not 'annoyance' represents a 'health impact' and instead focus on ways to minimize and attenuate these feelings of threat (risk) and stress at the community level. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Maximum-power-point tracking with reduced mechanical stress applied to wind-energy-conversion-systems

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, L.G. [Departamento de Electronica y Comunicaciones, Universidad de los Andes, nucleo la Hechicera, 5101 Merida (Venezuela); Figueres, E.; Garcera, G. [Grupo de Sistemas Electronicos Industriales, Universidad Politecnica de Valencia, Camino de vera s/n, 46022 Valencia (Spain); Carranza, O. [Escuela Superior de Computo, Instituto Politecnico Nacional, Av. Juan de Dios Batiz s/n, 07738 DF (Mexico)

    2010-07-15

    This paper presents an improved maximum-power-point tracking algorithm for wind-energy-conversion-systems. The proposed method significantly reduces the turbine mechanical stress with regard to conventional techniques, so that both the maintenance needs and the medium time between failures are expected to be improved. To achieve these objectives, a sensorless speed control loop receives its reference signal from a modified Perturb and Observe algorithm, in which the typical steps on the reference speed have been substituted by a fixed and well-defined slope ramp signal. As a result, it is achieved a soft dynamic response of both the torque and the speed of the wind turbine, so that the whole system suffers from a lower mechanical stress than with conventional P and O techniques. The proposed method has been applied to a wind turbine based on a permanent magnet synchronous generator operating at variable speed, which is connected to the distribution grid by means of a back to back converter. (author)

  15. Study on the Wake of a Miniature Wind Turbine Using the Reynolds Stress Model

    Directory of Open Access Journals (Sweden)

    Jianxiao Hu

    2016-09-01

    Full Text Available The Reynolds Stress Model (RSM is adopted to simulate the wind turbine wake and the simulation results are compared with the wind tunnel test data, simulation results from the standard k-ε model and a modified k-ε model. RSM shows good performance in predicting the turbine wakes velocity, turbulence intensity and the kinetic shear stress, while the k-ε based models fail to predict either wakes velocity or turbulence intensity. Simulation results show that the wake velocity will be recovered up to 90% at around 10 D downstream of the turbine (D denotes turbine rotor diameter and it stops at 91% at around 16 D downstream. The wake turbulence intensity reaches a maximum at around 5 D downstream of turbine. Further investigation shows that the horizontal profile of the wakes velocity can be approximated by a Gaussian distribution, and the turbulence intensity can be approximated by a bimodal distribution. The influence of the wakes effect is limited to within ±D in the across-wind direction. The turbine wakes show clear anisotropy, which could explain the incorrect estimation on the turbulence intensity with the extended k-ε model.

  16. Maintaining the Background Dust Opacity During Northern Hemisphere Summer Mars Using Wind Stress Based Dust Lifting

    Science.gov (United States)

    Jha, V.; Kahre, M. A.

    2017-12-01

    The Mars atmosphere has low levels of dust during Northern Hemisphere (NH) spring and summer (the non-dusty season) and increased levels during NH autumn and winter (the dusty season). In the absence of regional or global storms, dust devils and local storms maintain a background minimum dust loading during the non-dusty season. While observational surveys and Global Climate Model (GCM) studies suggest that dust devils are likely to be major contributors to the background haze during NH spring and summer, a complete understanding of the relative contribution of dust devils and local dust storms has not yet been achieved. We present preliminary results from an investigation that focuses on the effects of radiatively active water ice clouds on dust lifting processes during these seasons. Water ice clouds are known to affect atmospheric temperatures directly by absorption and emission of thermal infrared radiation and indirectly through dynamical feedbacks. Our goal is to understand how clouds affect the contribution by local (wind stress) dust storms to the background dust haze during NH spring and summer. The primary tool for this work is the NASA Ames Mars GCM, which contains physical parameterizations for a fully interactive dust cycle. Three simulations that included wind stress dust lifting were executed for a period of 5 Martian years: a case that included no cloud formation, a case that included radiatively inert cloud formation and a case that included radiatively active cloud (RAC) formation. Results show that when radiatively active clouds are included, the clouds in the aphelion cloud belt radiatively heat the atmosphere aloft in the tropics (Figure 1). This heating produces a stronger overturning circulation, which in turn produces an enhanced low-level flow in the Hadley cell return branch. The stronger low-level flow drives higher surface stresses and increased dust lifting in those locations. We examine how realistic these simulated results are by

  17. The Alignment of the Mean Wind and Stress Vectors in the Unstable Surface Layer

    Science.gov (United States)

    Bernardes, M.; Dias, N. L.

    2010-01-01

    A significant non-alignment between the mean horizontal wind vector and the stress vector was observed for turbulence measurements both above the water surface of a large lake, and over a land surface (soybean crop). Possible causes for this discrepancy such as flow distortion, averaging times and the procedure used for extracting the turbulent fluctuations (low-pass filtering and filter widths etc.), were dismissed after a detailed analysis. Minimum averaging times always less than 30 min were established by calculating ogives, and error bounds for the turbulent stresses were derived with three different approaches, based on integral time scales (first-crossing and lag-window estimates) and on a bootstrap technique. It was found that the mean absolute value of the angle between the mean wind and stress vectors is highly related to atmospheric stability, with the non-alignment increasing distinctively with increasing instability. Given a coordinate rotation that aligns the mean wind with the x direction, this behaviour can be explained by the growth of the relative error of the u- w component with instability. As a result, under more unstable conditions the u- w and the v- w components become of the same order of magnitude, and the local stress vector gives the impression of being non-aligned with the mean wind vector. The relative error of the v- w component is large enough to make it undistinguishable from zero throughout the range of stabilities. Therefore, the standard assumptions of Monin-Obukhov similarity theory hold: it is fair to assume that the v- w stress component is actually zero, and that the non-alignment is a purely statistical effect. An analysis of the dimensionless budgets of the u- w and the v- w components confirms this interpretation, with both shear and buoyant production of u- w decreasing with increasing instability. In the v- w budget, shear production is zero by definition, while buoyancy displays very low-intensity fluctuations around

  18. Barotropic Eulerian residual circulation in the Gulf of California due to the M{sub 2} tide and wind stress

    Energy Technology Data Exchange (ETDEWEB)

    Argote, M. L.; Lavin, M. F.; Amador, A. [Departamento de Oceanografia Fisica, CICESE, Ensenada, Baja California (Mexico)

    1998-07-01

    A vertically integrated, non-linear numerical model in finite differences is used to analyze two forcing mechanisms of the mean barotropic circulation in the Gulf of California: topographic rectification due to tidal currents (M{sub 2}) and wind stress. Under tidal forcing the nonlinearities of the momentum equations induce unorganized strong tidal induced residual currents (u{sub e} > 5 cm s{sup -}1) in the channels between the islands, and along-isobath anticyclonic circulation in the Northern Gulf, with speeds u{sub 3} < 2.5 cm s{sup -}1 over the edge of Delfin Basin. These numerical results are in agreement with analytical results, which indicate that the tidal-induced currents are mostly due to the advective terms, and that continuity and the Coriolis term (but regulated by bottom friction) are responsible for the along-isobath flow. The quadratic bottom friction plays a role in generating mean currents only in the very shallow area off the Colorado River Delta. The effect of wind stress was modeled by imposing upon the running M{sub 2} model a constant surface stress ( r = 0.016 Pa), from the NW for winter conditions and from the SE for summer conditions. The wind-induced circulation was obtained by averaging over a tidal cycle and then subtracting the tidal residuals. The two wind directions produce almost identical circulation patterns, but with opposite directions. For the NW wind stress, the main features of the predicted circulation are: (a) In the Northern Gulf an anticyclonic circulation pattern, with the strongest currents (up to {approx} 10 cm s-1) following the bathymetry of the rim of Delfin Basin, Wagner Basin and the mainland coast off Bahia Adair and Bahia San Jorge. There is also a southward flow along the peninsula coast, from the Colorado River to Bahia San Luis Gonzaga. (b) In the Southern Gulf, there is a strong flow ({approx} 10 to 15 cm s{sup -}1) to the SE over the continental shelf along the mainland coast. A somewhat less well

  19. Self-Imposed Creativity Constraints

    DEFF Research Database (Denmark)

    Biskjaer, Michael Mose

    2013-01-01

    and high concept awareness characterizing the humanities’ general mode of inquiry; (b) expertise in formulating new ‘big’ exploratory and unifying questions, which are waning in creativity research; and (c) greater versatility in the use of empirical data material, since the analytical, speculative...... increasingly fragmented and in need of new ‘big’ unifying questions. Hence the designation of the dissertation’s research approach. The four papers serve a dual purpose. They are contributions in their own right, and they provide partial answers to the overall research question. In this respect, the concept...... of the current dispersed studies on constraints in creativity, spanning psychology, engineering, philosophy, design, and aesthetics. (2) Definitions, concepts, and models of self-imposed creativity constraints for analytical application within and across creative domains, including the 6i model for demonstrating...

  20. Comparison of residual stresses in sand- and chill casting of ductile cast iron wind turbine main shafts

    DEFF Research Database (Denmark)

    Sonne, Mads Rostgaard; Frandsen, J. O.; Hattel, Jesper Henri

    2015-01-01

    In this work, simulations of pouring, solidification and cooling, and residual stress evolution of sand and chill cast wind turbine main shafts is performed. The models are made in the commercial software MAGMAsoft. As expected, the cooling rate of the sand casting is shown to be much lower than ...

  1. The Impact of Wind Speed Changes on the Surface Stress in the Weak-wind Stable Boundary Layer

    Science.gov (United States)

    Thomas, C. K.

    2015-12-01

    The behaviour of turbulent transport in the weak-wind stably stratified boundary layer is examined in terms of the non-stationarity of the wind field based upon field observations. Extensive sonic anemometer measurements from horizontal networks and vertical towers ranging from 12 to 20 m height were collected from three field programs in moderately sloped terrain with a varying degree of surface heterogeneity, namely the Shallow Cold Pool (SCP) and the Flow Over Snow Surfaces (FLOSS) II experiments in Colorado (USA), and the Advanced Canopy Resolution Experiment (ARCFLO) in Oregon (USA). The relationship of the friction velocity to the stratification and small non-stationary submeso motions is studied from several points of view and nominally quantified. The relationship of the turbulence to the stratification is less systematic than expected due to the important submeso-scale motions. Consequently, the roles of the wind speed and stratification are not adequately accommodated by a single non-dimensional combination, such as the bulk Richardson number. Howver, cause and effect relationships are difficult to isolate because the non-stationary momentum flux significantly modifies the profile of the non-stationary mean flow. The link between the turbulence and accelerations at the surface is examined in terms of the changing vertical structure of the wind profile and sudden increases of downward transport of momentum. The latter may be significant in explaining the small-scale weak turbulence during stable stratification and deviations from conventional flux-profile relationships.

  2. La comunidad imposible: atisbos sartreanos

    Directory of Open Access Journals (Sweden)

    Rius, Mercè

    2016-06-01

    Full Text Available In this paper, Sartre’s ontology is regarded as a precedent of the current political philosophers who state the impossibility of a being-in-common. In this sense they all distance themselves from Hegel and Heidegger, except that the thinkers of the impossible community cannot avoid speculating about death even if they deny that it has any sense. For Sartre though, the incompatibility between death and the freedom to exist remain essential, as well as a defense of realism. Moreover, this paper traces Sartre’s concept of the real and both his tendency and opposition to materialism.En este artículo se aborda la ontología sartreana a modo de precedente de la actual filosofía política que constata la imposibilidad del ser-en-común. Para ambas son Hegel y Heidegger los referentes de que distanciarse. Solo que los pensadores de la imposible comunidad no se abstienen de especular sobre la muerte, aunque nieguen su sentido. En cambio, para Sartre es esencial la incompatibilidad entre la muerte y la libertad del existir, así como la defensa del realismo. Se sigue aquí la pista a su concepto de lo real, a la vez que a su actitud tan propensa como adversa al materialismo.

  3. Influence of El Niño Wind Stress Anomalies on South Brazil Bight Ocean Volume Transports

    Directory of Open Access Journals (Sweden)

    Luiz Paulo de Freitas Assad

    2015-01-01

    Full Text Available The knowledge of wind stress variability could represent an important contribution to understand the variability over upper layer ocean volume transports. The South Brazilian Bight (SBB circulation had been studied by numerous researchers who predominantly attempted to estimate its meridional volume transport. The main objective and contribution of this study is to identify and quantify possible interannual variability in the ocean volume transport in the SBB induced by the sea surface wind stress field. A low resolution ocean global circulation model was implemented to investigate the volume transport variability. The results obtained indicate the occurrence of interannual variability in meridional ocean volume transports along three different zonal sections. These results also indicate the influence of a wind driven large-scale atmospheric process that alters locally the SBB and near-offshore region wind stress field and consequently causes interannual variability in the upper layer ocean volume transports. A strengthening of the southward flow in 25°S and 30°S was observed. The deep layer ocean volume transport in the three monitored sections indicates a potential dominance of other remote ocean processes. A small time lag between the integrated meridional volume transports changes in each monitored zonal section was observed.

  4. Hidden power system inflexibilities imposed by traditional unit commitment formulations

    International Nuclear Information System (INIS)

    Morales-España, Germán; Ramírez-Elizondo, Laura; Hobbs, Benjamin F.

    2017-01-01

    Highlights: • Quality and accuracy of traditional-energy- and power-based UCs are evaluated. • Real-time performance evaluation simulating “perfect” stochastic UCs. • Ideal energy-based stochastic UC formulations impose hidden system inflexibilities. • A deterministic power-based UC may outperform an ideal energy-based stochastic UC. • Power-based UC overcomes flaws of energy-based UC: lower cost and wind curtailment. - Abstract: Approximations made in traditional day-ahead unit commitment model formulations can result in suboptimal or even infeasible schedules for slow-start units and inaccurate predictions of actual costs and wind curtailment. With increasing wind penetration, these errors will become economically more significant. Here, we consider inaccuracies from three approximations: the use of hourly intervals in which energy production from each generator is modeled as being constant; the disregarding of startup and shutdown energy trajectories; and optimization based on expected wind profiles. The results of unit commitment formulations with those assumptions are compared to models that: (1) use a piecewise-linear power profiles of generation, load and wind, instead of the traditional stepwise energy profiles; (2) consider startup/shutdown trajectories; and (3) include many possible wind trajectories in a stochastic framework. The day-ahead hourly schedules of slow-start generators are then evaluated against actual wind and load profiles using a model real-time dispatch and quick-start unit commitment with a 5 min time step. We find that each simplification usually causes expected generation costs to increase by several percentage points, and results in significant understatement of expected wind curtailment and, in some cases, load interruptions. The inclusion of startup and shutdown trajectories often yielded the largest improvements in schedule performance.

  5. Impacts of the Mesoscale Ocean-Atmosphere Coupling on the Peru-Chile Ocean Dynamics: The Current-Induced Wind Stress Modulation

    Science.gov (United States)

    Oerder, V.; Colas, F.; Echevin, V.; Masson, S.; Lemarié, F.

    2018-02-01

    The ocean dynamical responses to the surface current-wind stress interaction at the oceanic mesoscale are investigated in the South-East Pacific using a high-resolution regional ocean-atmosphere coupled model. Two simulations are compared: one includes the surface current in the wind stress computation while the other does not. In the coastal region, absolute wind velocities are different between the two simulations but the wind stress remains very similar. As a consequence, the mean regional oceanic circulation is almost unchanged. On the contrary, the mesoscale activity is strongly reduced when taking into account the effect of the surface current on the wind stress. This is caused by a weakening of the eddy kinetic energy generation near the coast by the wind work and to intensified offshore eddy damping. We show that, above coherent eddies, the current-stress interaction generates eddy damping through Ekman pumping and eddy kinetic energy dissipation through wind work. This alters significantly the coherent eddy vertical structures compared with the control simulation, weakening the temperature and vorticity anomalies and increasing strongly the vertical velocity anomalies associated to eddies.

  6. Simulation Tool to Assess Mechanical and Electrical Stresses on Wind Turbine Generators: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Singh, M.; Muljadi, E.; Gevorgian, V.; Jonkman, J.

    2013-10-01

    Wind turbine generators (WTGs) consist of many different components to convert kinetic energy of the wind into electrical energy for end users. Wind energy is accessed to provide mechanical torque for driving the shaft of the electrical generator. The conversion from wind power to mechanical power is governed by the aerodynamic conversion. The aerodynamic-electrical-conversion efficiency of a WTGis influenced by the efficiency of the blades, the gearbox, the generator, and the power converter. This paper describes the use of MATLAB/Simulink to simulate the electrical and grid-related aspects of a WTG coupled with the FAST aero-elastic wind turbine computer-aided engineering tool to simulate the aerodynamic and mechanical aspects of a WTG. The combination of the two enables studiesinvolving both electrical and mechanical aspects of a WTG. This digest includes some examples of the capabilities of the FAST and MATLAB coupling, namely the effects of electrical faults on the blade moments.

  7. Structural monitoring and smart control of a wind turbine

    DEFF Research Database (Denmark)

    Caterino, Nicola; Trinchillo, Francesco; Georgakis, Christos T.

    2014-01-01

    The remarkable growth in height of wind turbines in the last years - for a higher production of electricity - makes the issues of monitoring and control of such challenging engineering works pressing than ever. The research herein proposed is addressed to monitor the structural demand imposed...... to the intensity of current feeding them. A specific control algorithm is proposed to drive MR dampers during severe wind loads. It aims to instantaneously calibrate the current to be supplied to the MR dampers, i.e. their “stiffness”, so as to reduce stresses and displacements imposed to the wind tower. The idea...... the control system under very different types of action. The results gathered, encouraging for further investigations, are presented and discussed, also looking at possible further developments....

  8. Discrete model in the analysis of residual stresses in unidirectional winding cylinders made of fiber-reinforced plastic

    Directory of Open Access Journals (Sweden)

    Turusov Robert Alekseevich

    2015-01-01

    Full Text Available Today works in cosmos and at great sea depths are becoming very current. In order to execute these works tanks with great mass perfection are needed, which represents the relation of the product of pressure and inner volume to its mass. Usually such tanks are usually produced as a cocoon by winding methods, which can be automated. The simplest model of a cocoon is a cylinder with hemispheric blinds at the edges. The radial stresses arise in thick walled composite cylinders due to anisotropic thermal shrinkage during cooling process after curing. It also can lead to formation of radial cracks. The results of the analyses when a material is simplified to a homogenous orthotropic material show a very small residual radial stress value. In this paper we have used discrete model to evaluate residual radial stresses in thick-walled unidirectional filament wound cylinder and the results were compared to the results of homogenous orthotropic model.

  9. Integration of complementary methods for monitoring stress/strain of wind turbine blades structures

    Directory of Open Access Journals (Sweden)

    Savin Adriana

    2017-01-01

    Full Text Available The most important part of wind turbine is the blade that must be tested during the fabrication and during the functioning when can be damaged by moisture absorption, fatigue, wind gusts or lightning strikes. The novelty of the paper is represented by the employing of wireless sensors embedded in a scalable wind turbine blade made from Glass Fiber Reinforced Plastics together with Fiber Bragg Gratings in order to effectuate structural health monitoring in static conditions. The sensors are placed on critical location on blade determined by FEM simulation and a comparison between the complementary methods is done.

  10. Numerical modeling of the response of Ceará continental shelf waters to wind stress forcing

    Directory of Open Access Journals (Sweden)

    Jacyra Soares

    1996-01-01

    Full Text Available Ceará shelf waters response to steady and transicnt wind forcing, from Ponta Cajuais (04°42'S, 37°19.5'W to Ponta de Itapagé (02°50.5'S, 40000'W, was studied using a hydrodynamic numerical model. The finitc difference model was based upon the equations for a barotropic ocean in general form: advective and quadratic surface and bottom stress terms were included. Seasonal differences in the shelf waters response were characterized by simulation of summer and winter forcing. Such experiments wcre conducted for both f and equatorial beta plane domains, without significative differences in the results. Transient shelf waters response were investigated using surface winds from the Fortaleza airport , during the period extending from 14/03 to 25/03n9. Model results were compared to current data collected during the same period; modeled currents were able to roughly describe observed current pattem, but not current intensity.A resposta das águas da plataforma continental do Ceará, de Ponta Cajuais (04°42'S, 37° 19,5'W, à forçante do vento estacionária e transiente foi estudada através de um modelo numérico hidrodinâmico. O modelo, na forma de diferenças finitas, utiliza as equações do movimento e da continuidade de massa para um oceano barotr6pico no caso mais geral: estão incluídos os termos advectivos, bem como o atrito com o fundo e a tensão de cisalhamento do vento, ambos parametrizados na forma quadrática. Variações sazonais na resposta estacionária das águas da plataforma continental, da área estudada, foram caracterizadas pela simulação das condições de verão e inverno da região. Os experimentos foram realizados no plano f e no plano p equatorial sem diferenças significativas nos resultados. A resposta transiente das águas da plataforma continental, da região escolhida, foi investigada usando uma série temporal de vento de superfície do Aeroporto de Fortaleza do período de 14 à 25 de março. O per

  11. Ocean Current and Wave Effects on Wind Stress Drag Coefficient Over the Global Ocean

    National Research Council Canada - National Science Library

    Kara, A. B; Metzger, E. J; Bourassa, Mark A

    2007-01-01

    ...%), but the notable impact of the latter is only evident in the tropical Pacific Ocean; (2) the presence of waves generally makes winds weaker and C0 lower almost everywhere over the global ocean; (3...

  12. Long term erosion resistance of unprotected radon suppression earth covers to wind stresses

    Energy Technology Data Exchange (ETDEWEB)

    Bander, T.J.

    1980-10-01

    Estimates of the amount of soil cover lost due to wind erosion are obtained using three different models. One model developed by W. S. Chepil employs a wind erosion equation which is based on wind tunnel and agricultural field measurements. The second model is based on an analytical solution of the saltation process obtained by P. R. Owen and agrees well with the data of Bagnold and Zingg. The third model was developed by Gillette and is based on a modification of the horizontal flux equation used by Bagnold and Chepil. Basic differences between the models are examined and a comparison of the soil movement predicted by each is presented. The usefulness of these wind erosion models as guidance in designing long term erosion-resistant covers for tailings piles is considered.

  13. Transformer sound level caused by core magnetostriction and winding stress displacement variation

    Directory of Open Access Journals (Sweden)

    Chang-Hung Hsu

    2017-05-01

    Full Text Available Magnetostriction caused by the exciting variation of the magnetic core and the current conducted by the winding wired to the core has a significant result impact on a power transformer. This paper presents the sound of a factory transformer before on-site delivery for no-load tests. This paper also discusses the winding characteristics from the transformer full-load tests. The simulation and the measurement for several transformers with capacities ranging from 15 to 60 MVA and high voltage 132kV to low voltage 33 kV are performed. This study compares the sound levels for transformers by no-load test (core/magnetostriction and full-load test (winding/displacement ε. The difference between the simulated and the measured sound levels is about 3dB. The results show that the sound level depends on several parameters, including winding displacement, capacity, mass of the core and windings. Comparative results of magnetic induction of cores and the electromagnetic force of windings for no-load and full-load conditions are examined.

  14. Imposing resolved turbulence in CFD simulations

    DEFF Research Database (Denmark)

    Gilling, L.; Sørensen, Niels N.

    2011-01-01

    In large‐eddy simulations, the inflow velocity field should contain resolved turbulence. This paper describes and analyzes two methods for imposing resolved turbulence in the interior of the domain in Computational Fluid Dynamics simulations. The intended application of the methods is to impose...... resolved turbulence immediately upstream of the region or structure of interest. Comparing to the alternative of imposing the turbulence at the inlet, there is a large potential to reduce the computational cost of the simulation by reducing the total number of cells. The reduction comes from a lower demand...... of modifying the source terms. None of the two methods can impose synthetic turbulence with good results, but it is shown that by running the turbulence field through a short precursor simulation, very good results are obtained. Copyright © 2011 John Wiley & Sons, Ltd....

  15. Surface Stress with Non-stationary Weak Winds and Stable Stratification

    Science.gov (United States)

    Mahrt, L.; Thomas, Christoph K.

    2016-04-01

    The behaviour of turbulent transport in the weak-wind, stably-stratified, boundary layer over land is examined in terms of the non-stationarity of the wind field using measurements from three field programs. These field programs include towers ranging from 12 to 20 m in height and an extensive horizontal network of sonic anemometers. The relationship of the friction velocity to the stratification and non-stationary submeso motions is investigated from several points of view and nominally quantified. The relationship of the turbulence to the stratification is less systematic than expected partly due to enhancement of the turbulence by submeso motions. Cause and effect relationships are difficult to isolate because the non-stationary momentum flux significantly modifies the profile of the non-stationary mean flow. The link between the turbulence and accelerations at the surface is examined in terms of the changing vertical structure of the wind profile and sudden increases in the downward transport of momentum.

  16. A Technique for Mitigating Thermal Stress and Extending Life Cycle of Power Electronic Converters Used for Wind Turbines

    Directory of Open Access Journals (Sweden)

    Canras Batunlu

    2015-11-01

    Full Text Available Over the last two decades, various models have been developed to assess and improve the reliability of power electronic conversion systems (PECs with a focus on those used for wind turbines. However, only few studies have dealt with mitigating the PECs thermo-mechanical effects on their reliability taking into account variations in wind characteristics. This work critically investigates this issue and attempts to offer a mitigating technique by, first, developing realistic full scale (FS and partial scale (PS induction generator models combined with two level back-to-back PECs. Subsequently, deriving a driving algorithm, which reduces PEC’s operating temperature by controlling its switching patterns. The developed switching procedure ensures minimum temperature fluctuations by adapting the variable DC link and system’s frequency of operation. It was found for both FS and PS topologies, that the generator side converters have higher mean junction temperatures where the grid side ones have more fluctuations on their thermal profile. The FS and PS cycling temperatures were reduced by 12 °C and 5 °C, respectively. Moreover, this led to a significant improvement in stress; approximately 27 MPa stress reduction for the FS induction generator PEC.

  17. Fabrication of 'TAMU3', a 'Wind/React' stress-managed 14T Nb3Sn block coil design

    International Nuclear Information System (INIS)

    Blackburn, R; Diaczenko, N; Elliott, T; Jaisle, A; McInturff, A; McIntyre, P; Sattarov, A

    2008-01-01

    The third phase of a high field dipole technology development, a full set (2+) of Stress-Managed winding modules is being fabricated. The dipole fabrication uses tooling, fixtures, procedures and technology modified and updated based on the second phase work and results reported plus new material developments and higher performance strand. The strand was furnished by the DOE HEP Nb 3 Sn conductor development program. The modules' cables were processed and cabled by the LBNL facility using the latest procedures developed. There were several new materials and processes introduced in this third phase to improve performance or simplify the fabrication which will be discussed. If all the performance inherent in the strand were to be achieved then the peak field should be higher than 14 T. The containment and flux return structure are the same as used in phase 2. This phase of the development will constitute the outer winding modules of a 'Collider' prototype Block dipole with Stress-Management. The lessons learned and the results obtained will be discussed

  18. Tower Design Load Verification on a 1-kW Wind Turbine: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Prascher, D.; Huskey, A.

    2004-11-01

    Wind turbine testing at the National Wind Technology Center (NWTC) has been done to characterize both tower top loads and thrust loads for small wind turbines, which is part of an ongoing effort to model and predict small wind turbine behavior and the resulting stresses imposed on the supporting tower. To these ends, a 1-kW furling wind turbine mounted on a 10-meter tower was instrumented and monitored via a data acquisition system for nearly a year. This test was conducted to verify the design loads as predicted by the simple design equations provided in the draft revision of the International Electrotechnical Commission (IEC) Small Wind Turbine Safety Standard 61400-02 CDV (hereafter called ''the draft Standard''). Data were captured for several operating conditions covered by the draft Standard. This paper addresses the collected data and what conclusions can be made from it.

  19. Stress analysis of the Euratom LCT case and winding as a contact problem

    International Nuclear Information System (INIS)

    Maurer, A.

    1984-01-01

    For the large coil task (LCT), the stress analysis of the superconducting toroidal field coil is performed using the finite element computer program MSC/NASTRAN. The previous analysis not only showed high stressed regions, but also made evident, that there is need for improvements in modeling and procedure. The most relevant results are presented in tables or graphs

  20. Oxidative stress is enhanced by hypothermia imposed on cerulein-induced pancreatitis in rats Aumento do estresse oxidativo após hipotermia em ratos com pancreatite induzida por ceruleína

    Directory of Open Access Journals (Sweden)

    Wellington Andraus

    2007-01-01

    Full Text Available BACKGROUND: Hypothermia is a frequent event in severe acute pancreatitis (AP and its real effects on the normal pancreas have not been well demonstrated. Moreover, neither have its effects on the outcome of acute pancreatitis been fully investigated. One hypothesis is that oxidative stress may be implicated in lesions caused or treated by hypothermia. AIM OF THE STUDY: To investigate the effect of hypothermia in cerulein-induced acute pancreatitis (CIAP in rats and the role played by oxidative stress in this process. METHODS: Male Wistar rats were divided into hypothermic and normothermic groups. Hypothermia was induced with a cold mattress and rectal temperature was kept at 30ºC for one hour. Acute pancreatitis was induced with 2 doses of cerulein (20 ìg/kg administered at a one-hour interval. Serum amylase, pancreas vascular permeability by Evan's blue method, pancreas wet-to-dry weight ratio and histopathology were analyzed in each group. RESULTS: When compared with normothermic rats, hypothermic animals, with cerulein-induced acute pancreatitis, showed higher levels of pancreatic vascular permeability (p BACKGROUND: Hipotermia é um evento freqüente em episódios de pancreatite aguda, contudo seu efeito real sobre pâncreas normal ainda não esta bem demonstrado. Além do mais, o efeito da hipotermia no decorrer da pancreatite aguda também não está completamente esclarecido. Uma das hipóteses sobre as causas das lesões causadas ou tratadas por hipotermia aventa a implicação de estresse oxidativo. OBJETIVOS: Investigar o efeito da hipotermia em ratos com pancreatite aguda induzida por ceruleína e o papel do estresse oxidativo neste processo. MÉTODOS: Ratos Wistar machos foram divididos em grupos hipotérmicos e normotérmicos. Hipotermia foi induzida com uma bolsa gelada de forma que a temperatura retal permanecesse em 30ºC por uma hora. Pancreatite aguda foi induzida com duas aplicações de ceruleína (20 ìg/kg administradas

  1. 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.

  2. Tropical Atlantic biases and their relation to surface wind stress and terrestrial precipitation

    Science.gov (United States)

    Richter, Ingo; Xie, Shang-Ping; Wittenberg, Andrew T.; Masumoto, Yukio

    2012-03-01

    Most coupled general circulation models (GCMs) perform poorly in the tropical Atlantic in terms of climatological seasonal cycle and interannual variability. The reasons for this poor performance are investigated in a suite of sensitivity experiments with the Geophysical Fluid Dynamics Laboratory (GFDL) coupled GCM. The experiments show that a significant portion of the equatorial SST biases in the model is due to weaker than observed equatorial easterlies during boreal spring. Due to these weak easterlies, the tilt of the equatorial thermocline is reduced, with shoaling in the west and deepening in the east. The erroneously deep thermocline in the east prevents cold tongue formation in the following season despite vigorous upwelling, thus inhibiting the Bjerknes feedback. It is further shown that the surface wind errors are due, in part, to deficient precipitation over equatorial South America and excessive precipitation over equatorial Africa, which already exist in the uncoupled atmospheric GCM. Additional tests indicate that the precipitation biases are highly sensitive to land surface conditions such as albedo and soil moisture. This suggests that improving the representation of land surface processes in GCMs offers a way of improving their performance in the tropical Atlantic. The weaker than observed equatorial easterlies also contribute remotely, via equatorial and coastal Kelvin waves, to the severe warm SST biases along the southwest African coast. However, the strength of the subtropical anticyclone and along-shore winds also play an important role.

  3. Tropical Atlantic biases and their relation to surface wind stress and terrestrial precipitation

    Energy Technology Data Exchange (ETDEWEB)

    Richter, Ingo [Research Institute for Global Change, JAMSTEC, Yokohama (Japan); University of Hawaii at Manoa, International Pacific Research Center, Honolulu, HI (United States); Xie, Shang-Ping [University of Hawaii at Manoa, International Pacific Research Center, Honolulu, HI (United States); University of Hawaii at Manoa, Department of Meteorology, Honolulu, HI (United States); Wittenberg, Andrew T. [NOAA/Geophysical Fluid Dynamics Laboratory, Princeton, NJ (United States); Masumoto, Yukio [Research Institute for Global Change, JAMSTEC, Yokohama (Japan)

    2012-03-15

    Most coupled general circulation models (GCMs) perform poorly in the tropical Atlantic in terms of climatological seasonal cycle and interannual variability. The reasons for this poor performance are investigated in a suite of sensitivity experiments with the Geophysical Fluid Dynamics Laboratory (GFDL) coupled GCM. The experiments show that a significant portion of the equatorial SST biases in the model is due to weaker than observed equatorial easterlies during boreal spring. Due to these weak easterlies, the tilt of the equatorial thermocline is reduced, with shoaling in the west and deepening in the east. The erroneously deep thermocline in the east prevents cold tongue formation in the following season despite vigorous upwelling, thus inhibiting the Bjerknes feedback. It is further shown that the surface wind errors are due, in part, to deficient precipitation over equatorial South America and excessive precipitation over equatorial Africa, which already exist in the uncoupled atmospheric GCM. Additional tests indicate that the precipitation biases are highly sensitive to land surface conditions such as albedo and soil moisture. This suggests that improving the representation of land surface processes in GCMs offers a way of improving their performance in the tropical Atlantic. The weaker than observed equatorial easterlies also contribute remotely, via equatorial and coastal Kelvin waves, to the severe warm SST biases along the southwest African coast. However, the strength of the subtropical anticyclone and along-shore winds also play an important role. (orig.)

  4. Variability of wind stress and currents at selected locations over the north Indian Ocean during 1977 and 1979 summer monsoon seasons

    Digital Repository Service at National Institute of Oceanography (India)

    Gopalakrishna, V.V.; Sadhuram, Y.; RameshBabu, V.; Rao, M.V.

    -77 and MONEX-79. In general, the surface wind stress and near surface current fields are strong during a good monsoon year (1977) as compared to those in a bad monsoon year (1979) under similar synoptic conditions together with the prevalence of high...

  5. Parametric Analysis of Forces and Stresses in Superconducting Quadrupole Sector Windings

    CERN Document Server

    Fessia, P; Todesco, E

    2009-01-01

    We first present a review of the existing analytical equations for electromagnetic forces and stress in a sector coil quadrupole, evaluating their extent of application in function of the coil geometrical layout. We analyze the distribution of stress provided on the coil retaining structure as well as on the coil mid plane, this one related to the degradation of critical current in the superconductor. We focus on the maximum compressive stress dependence on the magnetic gradient at short sample conditions, considering two possible low temperature superconductors: Nb-Ti and Nb3Sn. In the last part the effect of an iron yoke on the magnetic field and forces is presented, proposing a correction of the critical current density expression when an infinite permeable iron yoke is used.

  6. Parametric Analysis of Forces and Stresses in Superconducting Quadrupole Sector Windings

    CERN Document Server

    Fessia, P; Todesco, E

    2008-01-01

    We first present a review of the existing analytical equations for electromagnetic forces and stress in a sector coil quadrupole, evaluating their extent of application in function of the coil geometrical layout. We analyze the distribution of stress provided on the coil retaining structure as well as on the coil mid plane, this one related to the degradation of critical current in the superconductor. We focuse on the maximum compressive stress dependence on the magnetic gradient at short sample conditions, considering two possible low temperature superconductors: Nb-Ti and Nb3Sn. In the last part the effect of an iron yoke on the magnetic field and forces is presented, proposing a correction of the critical current density expression when an infinite permeable iron yoke is used.

  7. Alignment of stress, mean wind, and vertical gradient of the velocity vector

    DEFF Research Database (Denmark)

    Berg, Jacob; Mann, Jakob; Patton, E.G.

    2012-01-01

    In many applications in the atmospheric surface layer the turbulent-viscosity hypothesis is applied, i.e. the stress vector can be described through the vertical gradient of velocity. In the atmospheric surface layer, where the Coriolis force and baroclinic effects are considered negligible...

  8. Effect of load eccentricity and stress level on monopile support for offshore wind turbines

    DEFF Research Database (Denmark)

    Klinkvort, Rasmus Tofte; Hededal, Ole

    2014-01-01

    on which load is applied with a large eccentricity. With centrifuge tests as the basis, this paper investigates the behaviour of a rigid pile loaded with a high eccentricity. A test series was carried out to simulate idealized monotonic load cases for monopiles supporting an offshore wind turbine...... analysis and Rankine’s passive earth pressure coefficient as a normalization parameter. The normalized ultimate soil resistance was unaffected by acceleration level and load eccentricity, indicating that the failure mechanism was the same for all tests. Based on the centrifuge tests, a reformulation...... of soil–pile interaction curves is presented. The normalized initial stiffness of the soil–pile resistance curves was seen to increase linearly with depth in the centrifuge tests. The reformulation differs from current guidelines in terms of the shape of the interaction curve and magnitude of ultimate...

  9. Role of multiaxial stress state in the hydrogen-assisted rolling-contact fatigue in bearings for wind turbines

    Directory of Open Access Journals (Sweden)

    J. Toribio

    2015-07-01

    Full Text Available Offshore wind turbines often involve important engineering challenges such as the improvement of hydrogen embrittlement resistance of the turbine bearings. These elements frequently suffer the so-called phenomenon of hydrogen-assisted rolling-contact fatigue (HA-RCF as a consequence of the synergic action of the surrounding harsh environment (the lubricant supplying hydrogen to the material and the cyclic multiaxial stress state caused by in-service mechanical loading. Thus the complex phenomenon could be classified as hydrogen-assisted rolling-contact multiaxial fatigue (HA-RC-MF. This paper analyses, from the mechanical and the chemical points of view, the so-called ball-on-rod test, widely used to evaluate the hydrogen embrittlement susceptibility of turbine bearings. Both the stress-strain states and the steady-state hydrogen concentration distribution are studied, so that a better elucidation can be obtained of the potential fracture places where the hydrogen could be more harmful and, consequently, where the turbine bearings could fail during their life in service.

  10. DOCUMENT IMAGE REGISTRATION FOR IMPOSED LAYER EXTRACTION

    Directory of Open Access Journals (Sweden)

    Surabhi Narayan

    2017-02-01

    Full Text Available Extraction of filled-in information from document images in the presence of template poses challenges due to geometrical distortion. Filled-in document image consists of null background, general information foreground and vital information imposed layer. Template document image consists of null background and general information foreground layer. In this paper a novel document image registration technique has been proposed to extract imposed layer from input document image. A convex polygon is constructed around the content of the input and the template image using convex hull. The vertices of the convex polygons of input and template are paired based on minimum Euclidean distance. Each vertex of the input convex polygon is subjected to transformation for the permutable combinations of rotation and scaling. Translation is handled by tight crop. For every transformation of the input vertices, Minimum Hausdorff distance (MHD is computed. Minimum Hausdorff distance identifies the rotation and scaling values by which the input image should be transformed to align it to the template. Since transformation is an estimation process, the components in the input image do not overlay exactly on the components in the template, therefore connected component technique is applied to extract contour boxes at word level to identify partially overlapping components. Geometrical features such as density, area and degree of overlapping are extracted and compared between partially overlapping components to identify and eliminate components common to input image and template image. The residue constitutes imposed layer. Experimental results indicate the efficacy of the proposed model with computational complexity. Experiment has been conducted on variety of filled-in forms, applications and bank cheques. Data sets have been generated as test sets for comparative analysis.

  11. Effect of variable winds on current structure and Reynolds stresses in a tidal flow: analysis of experimental data in the eastern English Channel

    Directory of Open Access Journals (Sweden)

    K. A. Korotenko

    2012-11-01

    Full Text Available Wind and wave effects on tidal current structure and turbulence throughout the water column are examined using an upward-looking acoustic Doppler current profiler (ADCP. The instrument has been deployed on the seafloor of 18-m mean depth, off the north-eastern French coast in the eastern English Channel, over 12 tidal cycles, and covered the period of the transition from mean spring to neap tide, and forcing regimes varied from calm to moderate storm conditions. During storms, we observed gusty winds with magnitudes reaching 15 m s−1 and wave heights reaching up to 1.3 m. Analysis of velocity spectra revealed a noticeable contribution of wind-induced waves to spectral structure of velocity fluctuations within the subsurface layer. Near the surface, stormy winds and waves produced a significant intensification of velocity fluctuations, particularly when the sustained wind blew against the ebb tide flow. As during wavy periods, the variance-derived Reynolds stress estimates might include a wave-induced contamination, we applied the Variance Fit method to obtain unbiased stresses and other turbulent quantities. Over calm periods, the turbulent quantities usually decreased with height above the seabed. The stresses were found to vary regularly with the predominantly semidiurnal tidal flow. The along-shore stress being generally greater during the flood flow (~2.7 Pa than during the ebb flow (~−0.6 Pa. The turbulent kinetic energy production rate, P, and eddy viscosity, Az, followed a nearly regular cycle with close to a quarter-diurnal period. As for the stresses, near the seabed, we found the maximum values of estimated quantities of P and Az to be 0.1 Wm−3 and 0.5 m2 s−1, respectively, during the flood flow. Over the storm periods, we found the highest unbiased stress values (~−2.6 Pa during ebb when tidal currents were opposite to the

  12. Are birds stressed during long-term flights? A wind-tunnel study on circulating corticosterone in the red knot.

    Science.gov (United States)

    Jenni-Eiermann, Susanne; Hasselquist, Dennis; Lindström, Ake; Koolhaas, Anita; Piersma, Theunis

    2009-01-01

    During endurance flight most birds do not feed and have to rely on their body reserves. Fat and protein is catabolised to meet the high energetic demands. Even though the hormonal regulation of migration is complex and not yet fully understood, the adrenocortical hormone corticosterone crystallizes to play a major role in controlling physiological traits in migratory birds during flight. However, results from field studies are partially equivocal, not least because data from birds during endurance flight are hard to get and present mostly a momentary shot. A wind-tunnel experiment offered the possibility to measure repeatedly under controlled conditions the effect of long flights on the stress hormone corticosterone. In a long-distance migrating shorebird, the red knot Calidris canutus, we measured plasma concentrations of corticosterone within 3 min and after a restraint time of 30 min directly after 2h and 10h non-stop flights, respectively, and during rest. Baseline corticosterone levels were unchanged directly after the flights, indicating that endurance flight did not affect corticosterone levels. The adrenocortical response to restraint showed the typical rise in birds during rest, while birds after a 2 or 10h flight substantially decreased plasma corticosterone concentrations. We suggest that the negative adrenocortical response to restraint after flight is part of the mechanism to reduce the proteolytic effect of corticosterone to save muscle protein and to avoid muscle damaging effects.

  13. Human cold stress of strong local-wind "Hijikawa-arashi" in Japan, based on the UTCI index and thermo-physiological responses

    Science.gov (United States)

    Ohashi, Yukitaka; Katsuta, Takumi; Tani, Haruka; Okabayashi, Taiki; Miyahara, Satoshi; Miyashita, Ryoji

    2018-03-01

    We investigated the cold stress caused by a strong local wind called "Hijikawa-arashi," through in situ vital measurements and the Universal Thermal Climate Index (UTCI). This wind is a very interesting winter phenomenon, localized in an area within 1 km of the seashore in Ozu City, Ehime Prefecture in Japan. When a strong Hijikawa-arashi (HA) occurred at 14-15 m s-1, the UTCI decreased to - 30 °C along the bridge where commuting residents are the most exposed to strong and cold winds. On the bridge, most participants in our experiment felt "very cold" or "extremely cold." The UTCI of HA can be predicted from a multiple regression equation using wind speed and air temperature. The cold HA wind is also harmful to human thermo-physiological responses. It leads to higher blood pressure and increased heart rate, both of which act as cardiovascular stress triggers. Increases of 6-10 mmHg and 3-6 bpm for every 10 °C reduction in UTCI were seen on all observational days, including HA and non-HA days. In fact, the participants' body skin temperatures decreased by approximately 1.2 to 1.7 °C for every 10 °C reduction in UTCI. Thus, the UTCI variation due to the HA outbreak corresponded well with the cold sensation and thermo-physiological responses in humans. This result suggests that daily UTCI monitoring enables the prediction of thermo-physiological responses to the HA cold stress.

  14. FACTS Devices for Large Wind Power Plants

    DEFF Research Database (Denmark)

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

    2010-01-01

    Growing number of wind turbines is changing electricity generation profile all over the world. However, high wind energy penetration affects power system safety and stability. For this reason transmission system operators (TSO) impose more stringent connection requirements on the wind power plant...

  15. Is imposing risk awareness cultural imperialism?

    Science.gov (United States)

    Førde, O H

    1998-11-01

    Epidemiology is the main supplier of "bases of action" for preventive medicine and health promotion. Epidemiology and epidemiologists therefore have a responsibility not only for the quality and soundness of the risk estimates they deliver and for the way they are interpreted and used, but also for their consequences. In the industrialised world, the value of, and fascination with health is greater than ever, and the revelation from epidemiological research of new hazards and risks, conveyed to the public by the media, has become almost an every-day phenomenon. This "risk epidemic" in the modern media is paralleled in professional medical journals. It is in general endorsed by health promoters as a necessary foundation for increased health awareness and a desirable impetus for people to take responsibility for their own health through behavioural changes. Epidemiologists and health promoters, however, have in general not taken the possible side effects of increased risk awareness seriously enough. By increasing anxiety regarding disease, accidents and other adverse events, the risk epidemic enhances both health care dependence and health care consumption. More profoundly, and perhaps even more seriously, it changes the way people think about health, disease and death--and ultimately and at least potentially, their perspective on life more generally. The message from the odds ratios from epidemiological research advocates a rationalistic, individualistic, prospective life perspective where maximising control and minimising uncertainty is seen as a superior goal. The inconsistency between applying an expanded health concept, comprising elements of coping, self-realisation and psycho-physical functioning, and imposing intolerance to risk and uncertainty, is regularly overlooked. Acceptance and tolerance of risk and uncertainty, which are inherent elements of human life, is a prerequisite for coping and self-realisation. A further shift away from traditional working

  16. Wind Forcing of the Pacific Ocean Using Scatterometer Wind Data

    Science.gov (United States)

    Kelly, Kathryn A.

    1999-01-01

    The long-term objective of this research was an understanding of the wind-forced ocean circulation, particularly for the Pacific Ocean. To determine the ocean's response to the winds, we first needed to generate accurate maps of wind stress. For the ocean's response to wind stress we examined the sea surface height (SSH) both from altimeters and from numerical models for the Pacific Ocean.

  17. Anisotropy of the Reynolds stress tensor in the wakes of wind turbine arrays in Cartesian arrangements with counter-rotating rotors

    Science.gov (United States)

    Hamilton, Nicholas; Cal, Raúl Bayoán

    2015-01-01

    A 4 × 3 wind turbine array in a Cartesian arrangement was constructed in a wind tunnel setting with four configurations based on the rotational sense of the rotor blades. The fourth row of devices is considered to be in the fully developed turbine canopy for a Cartesian arrangement. Measurements of the flow field were made with stereo particle-image velocimetry immediately upstream and downstream of the selected model turbines. Rotational sense of the turbine blades is evident in the mean spanwise velocity W and the Reynolds shear stress - v w ¯ . The flux of kinetic energy is shown to be of greater magnitude following turbines in arrays where direction of rotation of the blades varies. Invariants of the normalized Reynolds stress anisotropy tensor (η and ξ) are plotted in the Lumley triangle and indicate that distinct characters of turbulence exist in regions of the wake following the nacelle and the rotor blade tips. Eigendecomposition of the tensor yields principle components and corresponding coordinate system transformations. Characteristic spheroids representing the balance of components in the normalized anisotropy tensor are composed with the eigenvalues yielding shapes predicted by the Lumley triangle. Rotation of the coordinate system defined by the eigenvectors demonstrates trends in the streamwise coordinate following the rotors, especially trailing the top-tip of the rotor and below the hub. Direction of rotation of rotor blades is shown by the orientation of characteristic spheroids according to principle axes. In the inflows of exit row turbines, the normalized Reynolds stress anisotropy tensor shows cumulative effects of the upstream turbines, tending toward prolate shapes for uniform rotational sense, oblate spheroids for streamwise organization of rotational senses, and a mixture of characteristic shapes when the rotation varies by row. Comparison between the invariants of the Reynolds stress anisotropy tensor and terms from the mean

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

    Energy Technology Data Exchange (ETDEWEB)

    Bander, T.J.

    1982-11-01

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

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

    International Nuclear Information System (INIS)

    Bander, T.J.

    1982-11-01

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

  20. 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

  1. Wakes in very large wind farms and the effect of neighbouring wind farms

    International Nuclear Information System (INIS)

    Nygaard, Nicolai Gayle

    2014-01-01

    We present the first analysis of wake losses in some of the largest offshore wind farms built to date. In addition, we give an example of the external wake losses that can be imposed by a neighbouring wind farm. Both situations lend insights to the wake phenomena in large offshore wind farm clusters. A simple wake model is compared to the data to assess the need for a more detailed physical description of large wind farm wakes

  2. The impact of non-stationary flows on the surface stress in the weak-wind stable boundary layer

    Science.gov (United States)

    Thomas, Christoph; Mahrt, Larry

    2016-04-01

    The behaviour of turbulent transport in the weak-wind stably stratified boundary layer is examined in terms of the non-stationarity of the wind field based upon field observations. Extensive sonic anemometer measurements from horizontal networks and vertical towers ranging from 12 to 20 m height and innovative fiber-optic distributed temperature sensing observations were collected from three field programs in moderately sloped terrain with a varying degree of surface heterogeneity, namely the Shallow Cold Pool (SCP) and the Flow Over Snow Surfaces (FLOSS) II experiments in Colorado (USA), and the Advanced Canopy Resolution Experiment (ARCFLO) in Oregon (USA). The relationship of the friction velocity to the stratification and small non-stationary submeso motions is studied from several points of view and nominally quantified. The relationship of the turbulence to the stratification is less systematic than expected due to the important submeso-scale motions. Consequently, the roles of the wind speed and stratification are not adequately accommodated by a single non-dimensional combination, such as the bulk Richardson number. However, cause and effect relationships are difficult to isolate because the non-stationary momentum flux significantly modifies the profile of the non-stationary mean flow. The link between the turbulence and accelerations at the surface is examined in terms of the changing vertical structure of the wind profile and sudden increases of downward transport of momentum. The latter may be significant in explaining the small-scale weak turbulence during stable stratification and deviations from conventional flux-profile relationships. Contrary to expectations, the vertical coherence was strongest for weakest winds and declined fast with increasing velocities, which suggests that submeso-scale motions are much deeper than previously thought.

  3. In-situ damage localization for a wind turbine blade through outlier analysis of SDDLV-induced stress resultants

    DEFF Research Database (Denmark)

    Ulriksen, Martin Dalgaard; Tcherniak, Dmitri; Hansen, Lasse Majgaard

    2017-01-01

    stress resultants approaching zero in the damaged elements. The proposed extension is based on outlier analysis of the characteristic stress resultants to discriminate between damaged elements and healthy ones; a procedure that previously, in the context of experiments with a small-scale blade, has...... proved to mitigate noise-induced anomalies and systematic, non-damage-associated adverse effects....

  4. Decadal Variations of the Western Subarctic Gyre and Main Pycnocline Depth due to Wind Stress Change in the Northern North Pacific

    Science.gov (United States)

    Nagano, A.; Wakita, M.

    2017-12-01

    From the late 1990s to the early 2000s, the western subarctic gyre of the North Pacific, a cyclonic circulation in the western subarctic region, shrank northward associated with a decadal increase of sea surface height (SSH). This gyre change displaced the main pycnocline (halocline) downward and is expected to contribute to the deepening of the overlying temperature minimum layer. This is considered to affect the biogeochemical conditions in the western subarctic region, where is known as substantially slow ocean acidification region. In this study, on the basis of wind stress field data in the subpolar region (40˚N—54˚N, 160˚E—135˚W) during 1979—2014 provided by U.S. National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis, we estimated the variation in SSH, solving the vorticity gradient equation on the beta plane. Decadal increase in SSH at Station K2 (47˚N, 160˚E), representative point of the western subarctic region, was well produced by the calculation, and the correlation coefficient with altimetric SSH exceeds 0.6. The calculated SSH variation consists of the variations due to the barotropic and baroclinic Rossby wave modes. The gyre shrinkage is found to be caused primarily by the barotropic response to the wind change in the whole subpolar region and secondary by the first baroclinic response. Meanwhile, the decadal deepening of the main pycnocline at K2 is attributed to the baroclinic responses of the higher (second, third, and fourth) vertical modes to the local wind change.

  5. Metric of the 2–6 day sea-surface temperature response to wind stress in the Tropical Pacific and its sensitivity to the K-Profile Parameterization of vertical mixing

    KAUST Repository

    Wagman, Benjamin M.

    2014-05-04

    Uncertainty in wind forcing has long hampered direct tests of ocean model output against observations for the purpose of refining the boundary layer K-Profile Parameterization (KPP) of oceanic vertical mixing. Considered here is a short-term metric that could be sensitive to the ways in which the KPP directly affects the adjustment of sea surface temperatures for a given change in wind stress. In particular a metric is developed based on the lagged correlation between the 2–6 day filtered wind stress and sea surface temperature. The metric is normalized by estimated observational and model uncertainties such that the significance of differences may be assessed. For this purpose multiple wind reanalysis products and their blended combinations were used to represent the range of forcing uncertainty, while perturbed KPP parameter model runs explore the sensitivity of the metric to the parameterization of vertical mixing. The correlation metric is sensitive to perturbations to most KPP parameters, in ways that accord with expectations, although only a few parameters show a sensitivity on the same order as the sensitivity to switching between wind products. This suggests that uncertainties in wind forcing continue to be a significant limitation for applying direct observational tests of KPP physics. Moreover, model correlations are biased high, suggesting that the model lacks or does not resolve sources of variability on the 2–6 day time scale.

  6. 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

  7. Hidden Power System Inflexibilities imposed by traditional unit commitment formulations

    NARCIS (Netherlands)

    Morales Espana, G.; Ramirez Elizondo, L.M.; Hobbs, Benjamin F.

    2017-01-01

    Approximations made in traditional day-ahead unit commitment model formulations can result in suboptimal or even infeasible schedules for slow-start units and inaccurate predictions of actual costs and wind curtailment. With increasing wind penetration, these errors will become economically more

  8. Stochastic Evaluation of Maximum Wind Installation in a Radial Distribution Network

    DEFF Research Database (Denmark)

    Chen, Peiyuan; Bak-Jensen, Birgitte; Chen, Zhe

    2011-01-01

    This paper proposes an optimization algorithm to find the maximum wind installation in a radial distribution network. The algorithm imposes a limit on the amount of wind energy that can be curtailed annually. The algorithm implements the wind turbine reactive power control and wind energy curtail...... executes reactive compensation and energy curtailment sequentially in an effective and efficient manner....

  9. 49 CFR 199.209 - Other requirements imposed by operators.

    Science.gov (United States)

    2010-10-01

    ... ALCOHOL TESTING Alcohol Misuse Prevention Program § 199.209 Other requirements imposed by operators. (a... authority of operators, or the rights of employees, with respect to the use or possession of alcohol, including authority and rights with respect to alcohol testing and rehabilitation. (b) Operators may, but...

  10. Alignment to natural and imposed mismatches between the senses

    NARCIS (Netherlands)

    van der Kooij, K.; Brenner, E.; van Beers, R.J.; Schot, W.D.; Smeets, J.B.J.

    2013-01-01

    Does the nervous system continuously realign the senses so that objects are seen and felt in the same place? Conflicting answers to this question have been given. Research imposing a sensory mismatch has provided evidence that the nervous system realigns the senses to reduce the mismatch. Other

  11. Modelling the water mass circulation in the Aegean Sea. Part I: wind stresses, thermal and haline fluxes

    Directory of Open Access Journals (Sweden)

    I. A. Valioulis

    Full Text Available The aim of this work is to develop a computer model capable of simulating the water mass circulation in the Aegean Sea. There is historical, phenomenological and recent experimental evidence of important hydrographical features whose causes have been variably identified as the highly complex bathymetry, the extreme seasonal variations in temperature, the considerable fresh water fluxes, and the large gradients in salinity or temperature across neighbouring water masses (Black Sea and Eastern Mediterranean. In the approach taken here, physical processes are introduced into the model one by one. This method reveals the parameters responsible for permanent and seasonal features of the Aegean Sea circulation. In the first part of the work reported herein, wind-induced circulation appears to be seasonally invariant. This yearly pattern is overcome by the inclusion of baroclinicity in the model in the form of surface thermohaline fluxes. The model shows an intricate pattern of sub-basin gyres and locally strong currents, permanent or seasonal, in accord with the experimental evidence.

  12. Modelling the water mass circulation in the Aegean Sea. Part I: wind stresses, thermal and haline fluxes

    Directory of Open Access Journals (Sweden)

    I. A. Valioulis

    1994-07-01

    Full Text Available The aim of this work is to develop a computer model capable of simulating the water mass circulation in the Aegean Sea. There is historical, phenomenological and recent experimental evidence of important hydrographical features whose causes have been variably identified as the highly complex bathymetry, the extreme seasonal variations in temperature, the considerable fresh water fluxes, and the large gradients in salinity or temperature across neighbouring water masses (Black Sea and Eastern Mediterranean. In the approach taken here, physical processes are introduced into the model one by one. This method reveals the parameters responsible for permanent and seasonal features of the Aegean Sea circulation. In the first part of the work reported herein, wind-induced circulation appears to be seasonally invariant. This yearly pattern is overcome by the inclusion of baroclinicity in the model in the form of surface thermohaline fluxes. The model shows an intricate pattern of sub-basin gyres and locally strong currents, permanent or seasonal, in accord with the experimental evidence.

  13. Modelling the effect of coating on the stresses and microstructure evolution in chill casting of wind turbine main shafts

    DEFF Research Database (Denmark)

    Sonne, Mads Rostgaard; Thorborg, J.; Hattel, Jesper Henri

    2017-01-01

    . Simulations of the casting process are performed with four different heat transfer coefficients (HTCs) between the casting and the chill, and the resulting transient stress fields are reported in the chill. The microstructural evolution in the casting in terms of the nodule count is also modelled......, it is concluded that the material quality obtained from casting the main shafts in chills (and hence the performance of the part) is still much better than for sand casting, even though a very thick layer of coating is applied. Copyright © 2017 John Wiley & Sons, Ltd....

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

    Indian Academy of Sciences (India)

    Service. References. Brown S, Nickling W G and Gillies J A 2008 A wind tunnel examination of shear stress partitioning for an assortment of surface roughness distribution; J. Geophys. Res. 113. F02S06, doi: 10.1029/2007JF000790. Buckley R 1987 The effect of sparse vegetation on the transport of dune sand by wind; ...

  15. 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...

  16. Cyber security issues imposed on nuclear power plants

    International Nuclear Information System (INIS)

    Kim, Do-Yeon

    2014-01-01

    Highlights: • Provide history of cyber attacks targeting at nuclear facilities. • Provide cyber security issues imposed on nuclear power plants. • Provide possible countermeasures for protecting nuclear power plants. - Abstract: With the introduction of new technology based on the increasing digitalization of control systems, the potential of cyber attacks has escalated into a serious threat for nuclear facilities, resulting in the advent of the Stuxnet. In this regard, the nuclear industry needs to consider several cyber security issues imposed on nuclear power plants, including regulatory guidelines and standards for cyber security, the possibility of Stuxnet-inherited malware attacks in the future, and countermeasures for protecting nuclear power plants against possible cyber attacks

  17. Optimal Design of DC Electromagnets Based on Imposed Dynamic Characteristics

    Directory of Open Access Journals (Sweden)

    Sergiu Ivas

    2016-10-01

    Full Text Available In this paper is proposed a method for computing of optimal geometric dimensions of a DC electromagnet, based on the imposed dynamical characteristics. For obtaining the optimal design, it is built the criterion function in an analytic form that may be optimized in the order to find the constructive solution. Numerical simulations performed in Matlab software confirm the proposed work. The presented method can be extended to other electromagnetic devices which frequently operate in dynamic regime.

  18. Distortions Imposed By Inflation on Historical-Cost Depreciation

    OpenAIRE

    Bravo-Ureta, Boris E.

    1983-01-01

    The use of historical-cost depreciation in periods of persistent inflation decreases the present value of depreciation deductions, thus understating the true economic cost of capital and increasing the real after-tax rate of return required by potential investors. Efforts to correct these problems by adopting depreciation methods that allow for artificially short recovery periods or accelerated rates do not provide an adequate solution. Distortions imposed by inflation on historical-cost depr...

  19. Arc Motion in an Obliquely Imposed Alternating Magnetic Field

    International Nuclear Information System (INIS)

    Akiho, R; Takeda, K; Sugimoto, M

    2012-01-01

    The arc motion is theoretically investigated under an alternating magnetic field imposed obliquely to the arc. The arc is known to oscillate on a 2-D plane when the alternating magnetic field is imposed perpendicularly to the arc. If the alternating magnetic field is imposed obliquely to the arc, then it is expected that the arc oscillates not on the 2-D plane but in a 3-D space. For this study, 3-D simulation was performed on the motion of the plasma gas under an alternating magnetic field crossing obliquely to the arc. It was also assumed that a stream line of the plasma gas represented the arc profile. The momentum equation for the plasma gas was solved together with the continuity equation. Governing parameters for the gas motion are θ (crossing angle), v 0 (initial velocity of the plasma gas), and λ. Parameter λ is defined as λ = (I a B 0 )/Q 0 . Numerical results are reported under different operating conditions such as magnetic flux densities and the angles between the arc and the magnetic flux. If the crossing angle is larger than 4/π, the arc might be extinguished because of the drastic increase of the arc length.

  20. Stress !!!

    OpenAIRE

    Fledderus, M.

    2012-01-01

    Twee op de vijf UT-studenten hebben last van ernstige studiestress, zo erg zelfs dat het ze in hun privéleven belemmert. Die cijfers komen overeen met het landelijk beeld van stress onder studenten. Samen met 14 andere universiteits- en hogeschoolbladen enquêteerde UT Nieuws bijna 5500 studenten. Opvallend is dat mannelijke studenten uit Twente zich veel minder druk lijken te maken over hun studie. Onder vrouwen ligt de stress juist erg hoog ten opzichte van het landelijk gemiddelde.

  1. Stress

    DEFF Research Database (Denmark)

    Keller, Hanne Dauer

    2015-01-01

    Kapitlet handler om stress som følelse, og det trækker primært på de få kvalitative undersøgelser, der er lavet af stressforløb.......Kapitlet handler om stress som følelse, og det trækker primært på de få kvalitative undersøgelser, der er lavet af stressforløb....

  2. Propulsion efficiency and imposed flow fields of a copepod jump

    DEFF Research Database (Denmark)

    Jiang, H.; Kiørboe, Thomas

    2011-01-01

    the imposed flow fields and associated energetics of jumps by means of computational fluid dynamics simulations by modeling the copepod as a self-propelled body. The computational fluid dynamics simulation was validated by particle image velocimetry data. The flow field generated by a repositioning jump...... velocity vectors pointing towards the copepod; such a flow field may inform the predator of the whereabouts of the escaping copepod prey. High Froude propulsion efficiency (0.94–0.98) was obtained for individual power stroke durations of all simulated jumps. This is unusual for small aquatic organisms...

  3. Stress !!!

    NARCIS (Netherlands)

    Fledderus, M.

    2012-01-01

    Twee op de vijf UT-studenten hebben last van ernstige studiestress, zo erg zelfs dat het ze in hun privéleven belemmert. Die cijfers komen overeen met het landelijk beeld van stress onder studenten. Samen met 14 andere universiteits- en hogeschoolbladen enquêteerde UT Nieuws bijna 5500 studenten.

  4. 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

  5. Global wind power development: Economics and policies

    International Nuclear Information System (INIS)

    Timilsina, Govinda R.; Cornelis van Kooten, G.; Narbel, Patrick A.

    2013-01-01

    Existing literature indicates that theoretically, the earth's wind energy supply potential significantly exceeds global energy demand. Yet, only 2–3% of global electricity demand is currently derived from wind power despite 27% annual growth in wind generating capacity over the last 17 years. More than 95% of total current wind power capacity is installed in the developed countries plus China and India. Our analysis shows that the economic competitiveness of wind power varies at wider range across countries or locations. A climate change damage cost of US$20/tCO 2 imposed to fossil fuels would make onshore wind competitive to all fossil fuels for power generation; however, the same would not happen to offshore wind, with few exceptions, even if the damage cost is increased to US$100/tCO 2 . To overcome a large number of technical, financial, institutional, market and other barriers to wind power, many countries have employed various policy instruments, including capital subsidies, tax incentives, tradable energy certificates, feed-in tariffs, grid access guarantees and mandatory standards. Besides, climate change mitigation policies, such as the Clean Development Mechanism, have played a pivotal role in promoting wind power. Despite these policies, intermittency, the main technical constraint, could remain as the major challenge to the future growth of wind power. - Highlights: • Global wind energy potential is enormous, yet the wind energy contribution is very small. • Existing policies are boosting development of wind power. • Costs of wind energy are higher than cost of fossil-based energies. • Reasonable premiums for climate change mitigation substantially promote wind power. • Intermittency is the key challenge to future development of wind power

  6. Grid integration impacts on wind turbine design and development

    DEFF Research Database (Denmark)

    Hansen, Anca Daniela; Cutululis, Nicolaos Antonio; Sørensen, Poul Ejnar

    2009-01-01

    This paper presents an overall perspective on contemporary issues like wind power plants and grid integration. The purpose is to present and discuss the impacts of emerging new grid connection requirements on modern wind turbines. The grid integration issue has caused several new challenges...... to the wind turbine design and development. The survival of different wind turbine concepts and controls is strongly conditioned by their ability to comply with stringent grid connection requirements, imposed by utility companies. Beside its impact on the mechanical design and control of wind turbines......, the grid integration aspect has also an effect on wind turbines' role in the power system, on wind turbine technologies' survival on the market, as well as on the wind turbines' loads. Over the last years, it became obviously, that there it is an increasing need for design and research of wind turbines...

  7. Arthropod Borne Diseases in Imposed War during 1980-88

    Directory of Open Access Journals (Sweden)

    M Khoobdel

    2008-06-01

    Full Text Available Background: Personnel of military forces have close contact with natural habitat and usually encounter with bite of arthropods and prone to be infected with arthropod borne diseases. The imposed war against Iran was one of the most important and the longest war in the Middle East and even in the world and military people faced various diseases. The aim of this study was to review prevalence of arthropod borne diseases and to collect relevant information and valuable experiences during the imposed war.Methods: The present survey is a historical research and cross-sectional study, focused on arthropod fauna, situation of different arthropod borne diseases and also the ways which military personnel used to protect themselves against them. The information was adopted from valid military health files and also interviewing people who participated in the war.Results: Scabies, cutaneous leishmaniasis, sandfly fever and pediculosis were more prevalent among other arthropod -borne diseases in Iran-Iraq war. Measures to control arthropods and diseases at wartime mainly included: scheduled spraying of pesticides, leishmanization and treatment of patients.Conclusion: Although measures used during the war to control arthropods were proper, however, due to needs and importance of military forces to new equipment and technologies, it is recommended to use deltamethrin-impreg­nated bed net, permethrin treated military uniforms and various insect repellents in future.

  8. Roles of wind stress and thermodynamic forcing in recent trends in Antarctic sea ice and Southern Ocean SST: An ocean-sea ice model study

    Science.gov (United States)

    Kusahara, Kazuya; Williams, Guy D.; Massom, Robert; Reid, Phillip; Hasumi, Hiroyasu

    2017-11-01

    In contrast to a strong decrease in Arctic sea ice extent, overall Antarctic sea ice extent has modestly increased since 1979. Several hypotheses have been proposed for the net Antarctic sea ice expansion, including atmosphere/ocean circulation and temperature changes, sea ice-atmospheric-ocean feedback, increased precipitation, and enhanced basal meltwater from ice shelves. Concomitant with this positive trend in Antarctic sea ice, sea surface temperatures (SSTs) over the Southern Ocean south of approximately 45°S have cooled over this period. However, the mechanisms responsible for the Antarctic sea ice expansion and the SST cooling trend remain poorly defined. Here, we conduct comprehensive sensitivity experiments using a coupled ocean-sea ice model with a steady-state ice shelf component in order to investigate the main drivers of recent trends in Antarctic sea ice and SST over the Southern Ocean. The results suggest that Antarctic sea ice expansion is mostly explained by trends in the thermodynamic surface forcing, notably cooling and drying and a reduction in longwave radiation. Similarly, thermodynamic forcing is found to be the main driver of the zonal SST cooling trend. While apparently less influential on sea ice extent and SST, wind stress plays a key role in sea ice motion, thickening coastal sea ice, and thinning and decreasing the concentration of ice in mid-pack regions of the Amundsen-eastern Ross seas and 65-95°E in winter-spring. Furthermore, the model suggests that ocean-ice shelf interaction does not significantly influence the observed trends in Antarctic sea ice coverage and Southern Ocean SST in recent decades.

  9. Optimizing transmission from distant wind farms

    International Nuclear Information System (INIS)

    Pattanariyankool, Sompop; Lave, Lester B.

    2010-01-01

    We explore the optimal size of the transmission line from distant wind farms, modeling the tradeoff between transmission cost and benefit from delivered wind power. We also examine the benefit of connecting a second wind farm, requiring additional transmission, in order to increase output smoothness. Since a wind farm has a low capacity factor, the transmission line would not be heavily loaded, on average; depending on the time profile of generation, for wind farms with capacity factor of 29-34%, profit is maximized for a line that is about 3/4 of the nameplate capacity of the wind farm. Although wind generation is inexpensive at a good site, transmitting wind power over 1600 km (about the distance from Wyoming to Los Angeles) doubles the delivered cost of power. As the price for power rises, the optimal capacity of transmission increases. Connecting wind farms lowers delivered cost when the wind farms are close, despite the high correlation of output over time. Imposing a penalty for failing to deliver minimum contracted supply leads to connecting more distant wind farms.

  10. Robust unit commitment with dispatchable wind power

    NARCIS (Netherlands)

    Morales Espana, G.; Lorca, Álvaro; de Weerdt, M.M.

    The increasing penetration of uncertain generation such as wind and solar in power systems imposes new challenges to the unit commitment (UC) problem, one of the most critical tasks in power systems operations. The two most common approaches to address these challenges — stochastic and robust

  11. 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

    1998-12-31

    During the wind power generator project a design algorithm for a gearless permanent magnet generator with an axially orientated magnetic flux was developed and a 10 kW model machine was constructed. Utilising the test results a variable wind speed system of 100 kW was designed that incorporates a permanent magnet generator, a frequency converter and a fuzzy controller. This system produces about 5-15% more energy than existing types and stresses to the blades are minimised. The type of generator designed in the project represents in general a gearless solution for slow-speed electrical drives. (orig.)

  12. Structural optimization under overhang constraints imposed by additive manufacturing technologies

    Science.gov (United States)

    Allaire, G.; Dapogny, C.; Estevez, R.; Faure, A.; Michailidis, G.

    2017-12-01

    This article addresses one of the major constraints imposed by additive manufacturing processes on shape optimization problems - that of overhangs, i.e. large regions hanging over void without sufficient support from the lower structure. After revisiting the 'classical' geometric criteria used in the literature, based on the angle between the structural boundary and the build direction, we propose a new mechanical constraint functional, which mimics the layer by layer construction process featured by additive manufacturing technologies, and thereby appeals to the physical origin of the difficulties caused by overhangs. This constraint, as well as some variants, is precisely defined; their shape derivatives are computed in the sense of Hadamard's method, and numerical strategies are extensively discussed, in two and three space dimensions, to efficiently deal with the appearance of overhang features in the course of shape optimization processes.

  13. Self-imposed length limits in recreational fisheries

    Science.gov (United States)

    Chizinski, Christopher J.; Martin, Dustin R.; Hurley, Keith L.; Pope, Kevin L.

    2014-01-01

    A primary motivating factor on the decision to harvest a fish among consumptive-orientated anglers is the size of the fish. There is likely a cost-benefit trade-off for harvest of individual fish that is size and species dependent, which should produce a logistic-type response of fish fate (release or harvest) as a function of fish size and species. We define the self-imposed length limit as the length at which a captured fish had a 50% probability of being harvested, which was selected because it marks the length of the fish where the probability of harvest becomes greater than the probability of release. We assessed the influences of fish size, catch per unit effort, size distribution of caught fish, and creel limit on the self-imposed length limits for bluegill Lepomis macrochirus, channel catfish Ictalurus punctatus, black crappie Pomoxis nigromaculatus and white crappie Pomoxis annularis combined, white bass Morone chrysops, and yellow perch Perca flavescens at six lakes in Nebraska, USA. As we predicted, the probability of harvest increased with increasing size for all species harvested, which supported the concept of a size-dependent trade-off in costs and benefits of harvesting individual fish. It was also clear that probability of harvest was not simply defined by fish length, but rather was likely influenced to various degrees by interactions between species, catch rate, size distribution, creel-limit regulation and fish size. A greater understanding of harvest decisions within the context of perceived likelihood that a creel limit will be realized by a given angler party, which is a function of fish availability, harvest regulation and angler skill and orientation, is needed to predict the influence that anglers have on fish communities and to allow managers to sustainable manage exploited fish populations in recreational fisheries.

  14. Wind Extraction for Natural Ventilation

    Science.gov (United States)

    Fagundes, Tadeu; Yaghoobian, Neda; Kumar, Rajan; Ordonez, Juan

    2017-11-01

    Due to the depletion of energy resources and the environmental impact of pollution and unsustainable energy resources, energy consumption has become one of the main concerns in our rapidly growing world. Natural ventilation, a traditional method to remove anthropogenic and solar heat gains, proved to be a cost-effective, alternative method to mechanical ventilation. However, while natural ventilation is simple in theory, its detailed design can be a challenge, particularly for wind-driven ventilation, which its performance highly involves the buildings' form, surrounding topography, turbulent flow characteristics, and climate. One of the main challenges with wind-driven natural ventilation schemes is due to the turbulent and unpredictable nature of the wind around the building that impose complex pressure loads on the structure. In practice, these challenges have resulted in founding the natural ventilation mainly on buoyancy (rather than the wind), as the primary force. This study is the initial step for investigating the physical principals of wind extraction over building walls and investigating strategies to reduce the dependence of the wind extraction on the incoming flow characteristics and the target building form.

  15. Stress.

    Science.gov (United States)

    Chambers, David W

    2008-01-01

    We all experience stress as a regular, and sometimes damaging and sometimes useful, part of our daily lives. In our normal ups and downs, we have our share of exhaustion, despondency, and outrage--matched with their corresponding positive moods. But burnout and workaholism are different. They are chronic, dysfunctional, self-reinforcing, life-shortening habits. Dentists, nurses, teachers, ministers, social workers, and entertainers are especially susceptible to burnout; not because they are hard-working professionals (they tend to be), but because they are caring perfectionists who share control for the success of what they do with others and perform under the scrutiny of their colleagues (they tend to). Workaholics are also trapped in self-sealing cycles, but the elements are ever-receding visions of control and using constant activity as a barrier against facing reality. This essay explores the symptoms, mechanisms, causes, and successful coping strategies for burnout and workaholism. It also takes a look at the general stress response on the physiological level and at some of the damage American society inflicts on itself.

  16. Association between the training loads imposed to amateur rugby sevens players and burnout syndrome

    Directory of Open Access Journals (Sweden)

    Alberto Sarly Coutinho Sobral

    2014-06-01

    Full Text Available Burnout syndrome has been shown to be increasingly prevalent in athletes, since it is related to factors that influence levels of stress during the preparation of sports. Therefore, it has been studied in several sports, but not in Rugby Seven. The aim of this study was to correlate the effects of training loads imposed on amateur Rugby Sevens players with the burnout questionnaire. Nine players (25 ± 5 years-old were evaluated before the preparatory period. Assessment included the measurement of the % fat percentage; nutritional status, stress, and aerobic power. During the preparatory period, once again, it was assessed the state of stress, aerobic power, and intensity of the training program. It was observed that there is no significant correlation between the intensity of the workout and Burnout scores (p> 0.05, nor between Burnout scores and aerobic capacity. However, there was significant a correlation between the intensity of training performed with aerobic power (p< 0.01. Therefore, it is concluded that a training program prescribed properly, prevents the onset of burnout syndrome in Rugby Sevens players.

  17. Contact stresses modeling at the Panda-type fiber single-layer winding and evaluation of their impact on the fiber optic properties

    Science.gov (United States)

    Lesnikova, Yu I.; Smetannikov, O. Yu; Trufanov, A. N.; Trufanov, N. A.

    2017-02-01

    The impact of contact transverse forces on the birefringence of the single-mode polarization-maintaining Panda-type fiber is numerically modeled. It has been established that with a single-row power winding on a cylindrical mandrel, the fiber tension at winding is the principal factor that influences birefringence. When coiling the fiber based on the local defect microbending, the birefringence at the microbending point differs from that of the free fiber by 1.3%.

  18. Thermal loading of wind power converter considering dynamics of wind speed

    DEFF Research Database (Denmark)

    Baygildina, Elvira; Peltoniemi, Pasi; Pyrhönen, Olli

    2013-01-01

    ), and the thermal stress of power devices is investigated from the frequency spectrum point of view of wind speed. It is concluded that because of the strong inertia effects by the aerodynamic behavior of wind turbines, thermal stress of the semiconductors is relatively more stable and only influenced by the low......The thermal loading of power semiconductors is a crucial performance related to the reliability and cost of the wind power converter. However, the thermal loading impacts by the variation of wind speeds have not yet been clarified, especially when considering the aerodynamic behavior of the wind...

  19. The corporation and the community: Credibility, legitimacy, and imposed risk

    Energy Technology Data Exchange (ETDEWEB)

    Wade, C. (ed.) (Los Alamos National Lab., NM (United States)); Rosenthal, I. (Pennsylvania Univ., Philadelphia, PA (United States). Center for Risk and Decision Processes)

    1991-10-01

    In this age of rapid changes, large segments of society no longer trust any institution or authority in regard to pronouncements on what is safe. Because of this distrust, the public has demanded and obtained increased rights for individuals to intervene directly in decisions affecting them. Rosenthal warns that an organization that just fulfills its legal requirements for safety is no longer doing enough. Industry leaders must work toward re-establishing credibility by identifying persons who are potentially at risk as a result of industry activities, involving them in the communication process, and justifying the firm's social benefits. Seeking social legitimacy, chemical manufacturers have formed self-assessment groups and community councils, which have reaped unexpected benefits but have forced them to deal with issues they would have preferred to avoid. To industry leaders who contend that these types of activities are not worth the effort, Rosenthal presents a timely warning. Government and business must reduce public concerns significantly and make stakeholders more willing to tolerate imposed risk because of perceived benefits. It the public's concern is not reduced, we will all be required to make greater and greater investments in an inefficient and largely fruitless pursuit of absolute safety. 16 refs.

  20. SAR moving object imaging using sparsity imposing priors

    Science.gov (United States)

    Önhon, N. Özben; Çetin, Müjdat

    2017-12-01

    Synthetic aperture radar (SAR) returns from a scene with motion can be viewed as data from a stationary scene, but with phase errors due to motion. Based on this perspective, we formulate the problem of SAR imaging of motion-containing scenes as one of joint imaging and phase error compensation. The proposed method is based on the minimization of a cost function which involves sparsity-imposing regularization terms on the reflectivity field to be imaged, considering that it admits a sparse representation as well as on the spatial structure of the motion-related phase errors, reflecting the assumption that only a small percentage of the entire scene contains moving objects. To incorporate the spatial structure of the phase errors into the problem, we provide three different sparsity-enforcing prior terms. In order to achieve computational gains, we also present a two-step version of our approach, which first determines regions of interest that are likely to contain the moving objects and then applies our sparsity-driven approach for joint image reconstruction and autofocusing in such a spatially constrained setting. Our preliminary experiments demonstrate the effectiveness of this new moving target SAR imaging approach.

  1. The corporation and the community: Credibility, legitimacy, and imposed risk

    International Nuclear Information System (INIS)

    Wade, C.; Rosenthal, I.

    1991-10-01

    In this age of rapid changes, large segments of society no longer trust any institution or authority in regard to pronouncements on what is safe. Because of this distrust, the public has demanded and obtained increased rights for individuals to intervene directly in decisions affecting them. Rosenthal warns that an organization that just fulfills its legal requirements for safety is no longer doing enough. Industry leaders must work toward re-establishing credibility by identifying persons who are potentially at risk as a result of industry activities, involving them in the communication process, and justifying the firm's social benefits. Seeking social legitimacy, chemical manufacturers have formed self-assessment groups and community councils, which have reaped unexpected benefits but have forced them to deal with issues they would have preferred to avoid. To industry leaders who contend that these types of activities are not worth the effort, Rosenthal presents a timely warning. Government and business must reduce public concerns significantly and make stakeholders more willing to tolerate imposed risk because of perceived benefits. It the public's concern is not reduced, we will all be required to make greater and greater investments in an inefficient and largely fruitless pursuit of absolute safety. 16 refs

  2. WIND VARIABILITY IN BZ CAMELOPARDALIS

    International Nuclear Information System (INIS)

    Honeycutt, R. K.; Kafka, S.; Robertson, J. W.

    2013-01-01

    Sequences of spectra of the nova-like cataclysmic variable (CV) BZ Cam were acquired on nine nights in 2005-2006 in order to study the time development of episodes of wind activity known to occur frequently in this star. We confirm the results of Ringwald and Naylor that the P-Cygni absorption components of the lines mostly evolve from higher expansion velocity to lower velocity as an episode progresses. We also commonly find blueshifted emission components in the Hα line profile, whose velocities and durations strongly suggest that they are also due to the wind. Curiously, Ringwald and Naylor reported common occurrences of redshifted Hα emission components in their BZ Cam spectra. We have attributed these emission components in Hα to occasions when gas concentrations in the bipolar wind (both front side and back side) become manifested as emission lines as they move beyond the disk's outer edge. We also suggest, based on changes in the P-Cygni profiles during an episode, that the progression from larger to smaller expansion velocities is due to the higher velocity portions of a wind concentration moving beyond the edge of the continuum light of the disk first, leaving a net redward shift of the remaining absorption profile. We derive a new orbital ephemeris for BZ Cam, using the radial velocity of the core of the He I λ5876 line, finding P = 0.15353(4). Using this period, the wind episodes in BZ Cam are found to be concentrated near the inferior conjunction of the emission line source. This result helps confirm that the winds in nova-like CVs are often phase dependent, in spite of the puzzling implication that such winds lack axisymmetry. We argue that the radiation-driven wind in BZ Cam receives an initial boost by acting on gas that has been lifted above the disk by the interaction of the accretion stream with the disk, thereby imposing flickering timescales onto the wind events, as well as leading to an orbital modulation of the wind due to the non

  3. 42 CFR 488.430 - Civil money penalties: Basis for imposing penalty.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 5 2010-10-01 2010-10-01 false Civil money penalties: Basis for imposing penalty... PROCEDURES Enforcement of Compliance for Long-Term Care Facilities with Deficiencies § 488.430 Civil money penalties: Basis for imposing penalty. (a) CMS or the State may impose a civil money penalty for either the...

  4. 26 CFR 1.802-3 - Tax imposed on life insurance companies.

    Science.gov (United States)

    2010-04-01

    ... 26 Internal Revenue 8 2010-04-01 2010-04-01 false Tax imposed on life insurance companies. 1.802-3... TAX (CONTINUED) INCOME TAXES Life Insurance Companies § 1.802-3 Tax imposed on life insurance companies. (a) In general. For taxable years beginning after December 31, 1957, section 802(a)(1) imposes a...

  5. 26 CFR 1.1374-1A - Tax imposed on certain capital gains.

    Science.gov (United States)

    2010-04-01

    ... TAX (CONTINUED) INCOME TAXES Section 1374 Before the Tax Reform Act of 1986 § 1.1374-1A Tax imposed on... 26 Internal Revenue 11 2010-04-01 2010-04-01 true Tax imposed on certain capital gains. 1.1374-1A... 1374 imposes a tax (computed under paragraph (b) of this section) on the income of such corporation...

  6. 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.

  7. 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...

  8. Damage Characterization of EBC-SiCSiC Ceramic Matrix Composites Under Imposed Thermal Gradient Testing

    Science.gov (United States)

    Appleby, Matthew P.; Morscher, Gregory N.; Zhu, Dongming

    2014-01-01

    Due to their high temperature capabilities, Ceramic Matrix Composite (CMC) components are being developed for use in hot-section aerospace engine applications. Harsh engine environments have led to the development of Environmental Barrier Coatings (EBCs) for silicon-based CMCs to further increase thermal and environmental capabilities. This study aims at understanding the damage mechanisms associated with these materials under simulated operating conditions. A high heat-flux laser testing rig capable of imposing large through-thickness thermal gradients by means of controlled laser beam heating and back-side air cooling is used. Tests are performed on uncoated composites, as well as CMC substrates that have been coated with state-of-the-art ceramic EBC systems. Results show that the use of the EBCs may help increase temperature capability and creep resistance by reducing the effects of stressed oxidation and environmental degradation. Also, the ability of electrical resistance (ER) and acoustic emission (AE) measurements to monitor material condition and damage state during high temperature testing is shown; suggesting their usefulness as a valuable health monitoring technique. Micromechanics models are used to describe the localized stress state of the composite system, which is utilized along with ER modeling concepts to develop an electromechanical model capable of characterizing material behavior.

  9. 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...

  10. Rigid MATLAB drivetrain model of a 500 kW wind turbine for predicting maximum gear tooth stresses in a planetary gearbox using multibody gear constraints

    DEFF Research Database (Denmark)

    Jørgensen, Martin Felix; Pedersen, Niels Leergaard; Sørensen, Jens Nørkær

    2014-01-01

    The aeroelastic FLEX 5 code and a semi-advanced rigid multibody model has been utilized for simulating drivetrain forces and moments in a real 500 kW wind turbine. Experimental validation is carried out with results based on known physical properties of the blades, tower, hub, gearbox, shaft and ...

  11. Evaluation of environmental stress imposed by a coal-ash effluent: Wisconsin power plant impact study

    Energy Technology Data Exchange (ETDEWEB)

    Webster, K.E.; Forbes, A.M.; Magnuson, J.L.

    1985-06-01

    Effluent discharged from the coal-ash settling basin of the Columbia Generating Station (Wisconsin) modified water chemistry (increased trace metal concentrations, suspended solids and dissolved materials) and substrate quality (precipitation of chemical floc) in the receiving stream, the ash pit drain. To test the hypothesis that habitat avoidance could account for declines in macroinvertebrate density observed after discharge began, drift rates of two species were measured in laboratory streams containing combinations of reference and coal-ash-modified substrate and water. Contrary to the hypothesis, drift was uniformly lower in laboratory streams containing modified substrate and/or water compared to the reference condition for Gammarus pseudolimnaeus and Asellus racovitzai.

  12. Arbuscular mycorrhizal symbiosis alleviates drought stress imposed on Knautia arvensis plants in serpentine soil

    Czech Academy of Sciences Publication Activity Database

    Doubková, Pavla; Vlasáková, E.; Sudová, Radka

    2013-01-01

    Roč. 370, 1-2 (2013), s. 149-161 ISSN 0032-079X R&D Projects: GA AV ČR KJB600050812 Institutional support: RVO:67985939 Keywords : arbuscular mycorrhizal fungi * drought * serpentine soil Subject RIV: EF - Botanics Impact factor: 3.235, year: 2013

  13. Assessing spacing impact on coherent features in a wind turbine array boundary layer

    Directory of Open Access Journals (Sweden)

    N. Ali

    2018-02-01

    Full Text Available As wind farms become larger, the spacing between turbines becomes a significant design consideration that can impose serious economic constraints. To investigate the turbulent flow structures in a 4 × 3 Cartesian wind turbine array boundary layer (WTABL, a wind tunnel experiment was carried out parameterizing the streamwise and spanwise wind turbine spacing. Four cases are chosen spacing turbines by 6 or 3D in the streamwise direction, and 3 or 1.5D in the spanwise direction, where D = 12 cm is the rotor diameter. Data are obtained experimentally using stereo particle image velocimetry. Mean streamwise velocity showed maximum values upstream of the turbine with the spacing of 6 and 3D in the streamwise and spanwise direction, respectively. Fixing the spanwise turbine spacing to 3D, variations in the streamwise spacing influence the turbulent flow structure and the power available to following wind turbines. Quantitative comparisons are made through spatial averaging, shifting measurement data and interpolating to account for the full range between devices to obtain data independent of array spacing. The largest averaged Reynolds stress is seen in cases with spacing of 3D × 3D. Snapshot proper orthogonal decomposition (POD was employed to identify the flow structures based on the turbulence kinetic energy content. The maximum turbulence kinetic energy content in the first POD mode is seen for turbine spacing of 6D × 1.5D. The flow upstream of each wind turbine converges faster than the flow downstream according to accumulation of turbulence kinetic energy by POD modes, regardless of spacing. The streamwise-averaged profile of the Reynolds stress is reconstructed using a specific number of modes for each case; the case of 6D × 1.5D spacing shows the fastest reconstruction to compare the rate of reconstruction of statistical profiles. Intermediate modes are also used to reconstruct the averaged profile and show that the

  14. 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

  15. 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.

  16. 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.

  17. Wind effect in turbulence parametrization

    Science.gov (United States)

    Colombini, M.; Stocchino, A.

    2005-09-01

    The action of wind blowing over a closed basin ultimately results in a steady shear-induced circulation pattern and in a leeward rising of the free surface—and a corresponding windward lowering—known as wind set-up. If the horizontal dimensions of the basin are large with respect to the average flow depth, the occurrence of local quasi-equilibrium conditions can be expected, i.e. the flow can be assumed to be locally driven only by the wind stress and by the opposing free surface gradient due to set-up. This wind-induced flow configuration shows a strong similarity with turbulent Couette-Poiseuille flow, the one dimensional flow between parallel plates generated by the simultaneous action of a constant pressure gradient and of the shear induced by the relative motion of the plates. A two-equation turbulence closure is then employed to perform a numerical study of turbulent Couette-Poiseuille flows for different values of the ratio of the shear stresses at the two walls. The resulting eddy viscosity vertical distributions are analyzed in order to devise analytical profiles of eddy viscosity that account for the effect of wind. The results of this study, beside allowing for a physical insight on the turbulence process of this class of flows, will allow for a more accurate description of the wind effect to be included in the formulation of quasi-3D and 3D models of lagoon hydrodynamics.

  18. TOPFARM - next generation design tool for optimisation of wind farm topology and operation

    DEFF Research Database (Denmark)

    Larsen, Gunner Chr.; Aagaard Madsen, Helge; Troldborg, Niels

    The present report is the publishable final activity report for the EU project TOPFARM. The project has been running from 1st December 2007 to 30th November 2010, and has successfully addressed optimization of wind farm topology and control strategy based on aero-elastic modeling of loads as well...... as of power production as seen in an economical perspective. Crucial factors in this regard are the overall wind climate at the wind farm site, the position of the individual wind turbines, the wind turbine characteristics, the internal wind farm wind climate, the wind turbine control/operation strategy...... for wind turbines interacting through wakes, various cost models, the optimization strategy and a priori defined constraints imposed on the wind farm topology. In TOPFARM, the object function used in the optimization platform is formulated in economical terms, thus ensuring the optimal balance between...

  19. Scenarios of hydrogen production from wind power

    Energy Technology Data Exchange (ETDEWEB)

    Klaric, Mario

    2010-09-15

    Since almost total amount of hydrogen is currently being produced from natural gas, other ways of cleaner and 'more renewable' production should be made feasible in order to make benchmarks for total 'hydrogen economy'. Hydrogen production from wind power combined with electrolysis imposes as one possible framework for new economy development. In this paper various wind-to-hydrogen scenarios were calculated. Cash flows of asset based project financing were used as decision making tool. Most important parameters were identified and strategies for further research and development and resource allocation are suggested.

  20. 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.)

  1. 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

  2. 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.

  3. Lethal Consequences of Overcoming Metabolic Restrictions Imposed on a Cooperative Bacterial Population.

    Science.gov (United States)

    Goo, Eunhye; Kang, Yongsung; Lim, Jae Yun; Ham, Hyeonheui; Hwang, Ingyu

    2017-02-28

    Quorum sensing (QS) controls cooperative activities in many Proteobacteria In some species, QS-dependent specific metabolism contributes to the stability of the cooperation. However, the mechanism by which QS and metabolic networks have coevolved to support stable public good cooperation and maintenance of the cooperative group remains unknown. Here we explored the underlying mechanisms of QS-controlled central metabolism in the evolutionary aspects of cooperation. In Burkholderia glumae , the QS-dependent glyoxylate cycle plays an important role in cooperativity. A bifunctional QS-dependent transcriptional regulator, QsmR, rewired central metabolism to utilize the glyoxylate cycle rather than the tricarboxylic acid cycle. Defects in the glyoxylate cycle caused metabolic imbalance and triggered high expression of the stress-responsive chaperonin GroEL. High-level expression of GroEL in glyoxylate cycle mutants interfered with the biosynthesis of a public resource, oxalate, by physically interrupting the oxalate biosynthetic enzyme ObcA. Under such destabilized cooperativity conditions, spontaneous mutations in the qsmR gene in glyoxylate cycle mutants occurred to relieve metabolic stresses, but these mutants lost QsmR-mediated pleiotropy. Overcoming the metabolic restrictions imposed on the population of cooperators among glyoxylate cycle mutants resulted in the occurrence and selection of spontaneous qsmR mutants despite the loss of other important functions. These results provide insight into how QS bacteria have evolved to maintain stable cooperation via QS-mediated metabolic coordination. IMPORTANCE We address how quorum sensing (QS) has coevolved with metabolic networks to maintain bacterial sociality. We found that QS-mediated metabolic rewiring is critical for sustainable bacterial cooperation in Burkholderia glumae The loss of the glyoxylate cycle triggered the expression of the stress-responsive molecular chaperonin GroEL. Excessive biosynthesis of Gro

  4. Wind climate modeling using Weibull and extreme value distribution ...

    African Journals Online (AJOL)

    The expected number of stress cycles in the projected working life of a structure is related to the expected number of hours in the critical wind speed range and wind climate modelling is required to know this. The most popular model for this purpose is Weibull distribution. Again, wind energy is proportional to the cube of the ...

  5. Probabilistic Wind Power Forecasting with Hybrid Artificial Neural Networks

    DEFF Research Database (Denmark)

    Wan, Can; Song, Yonghua; Xu, Zhao

    2016-01-01

    The uncertainty of wind power generation imposes significant challenges to optimal operation and control of electricity networks with increasing wind power penetration. To effectively address the uncertainties in wind power forecasts, probabilistic forecasts that can quantify the associated...... via a bootstrap technique. Subsequently, the maximum likelihood estimation method is employed to construct a distinct neural network to estimate the noise variance of forecasting results. The proposed approach has been tested on multi-step forecasting of high-resolution (10-min) wind power using...... actual wind power data from Denmark. The numerical results demonstrate that the proposed hybrid artificial neural network approach is effective and efficient for probabilistic forecasting of wind power and has high potential in practical applications....

  6. Low-cost Triangular Lattice Towers for Small Wind Turbines

    Science.gov (United States)

    Adhikari, Ram Chandra

    This thesis focuses on the study of low-cost steel and bamboo triangular lattice towers for small wind turbines. The core objective is to determine the material properties of bamboo and assess the feasibility of bamboo towers. Using the experimentally determined buckling resistance, elastic modulus, and Poisson's ratio, a 12 m high triangular lattice tower for a 500W wind turbine has been modeled as a tripod to formulate the analytical solutions for the stresses and tower deflections, which enables design of the tower based on buckling strength of tower legs. The tripod formulation combines the imposed loads, the base distance between the legs and tower height, and cross-sectional dimensions of the tower legs. The tripod model was used as a reference for the initial design of the bamboo tower and extended to finite element analysis. A 12 m high steel lattice tower was also designed for the same turbine to serve as a comparison to the bamboo tower. The primary result of this work indicates that bamboo is a valid structural material. The commercial software package ANSYS APDL was used to carry out the tower analysis, evaluate the validity of the tripod model, and extend the analysis for the tower design. For this purpose, a 12 m high steel lattice tower for a 500 W wind turbine was examined. Comparison of finite element analysis and analytical solution has shown that tripod model can be accurately used in the design of lattice towers. The tower designs were based on the loads and safety requirements of international standard for small wind turbine safety, IEC 61400-2. For connecting the bamboo sections in the lattice tower, a steel-bamboo adhesive joint combined with conventional lashing has been proposed. Also, considering the low durability of bamboo, periodic replacement of tower members has been proposed. The result of this study has established that bamboo could be used to construct cost-effective and lightweight lattice towers for wind turbines of 500 Watt

  7. Estimating the offsite household damages from wind erosion in the western United States. Staff report

    Energy Technology Data Exchange (ETDEWEB)

    Piper, S.; Lee, L.K.

    1989-06-01

    Wind erosion contributes significantly to particulate air pollution in some regions of the Western United States. As a result, wind erosion imposes damages on households in the form of increased interior and exterior cleaning, reduced recreational opportunities, and impaired health. Costs are difficult to estimate because of limited data availability. However, damages appear to be much larger offsite than onsite.

  8. Differences in the heat stress associated with white sportswear and being semi-nude in exercising humans under conditions of radiant heat and wind at a wet bulb globe temperature of greater than 28 °C.

    Science.gov (United States)

    Tsuji, Michio; Kume, Masashi; Tuneoka, Hideyuki; Yoshida, Tetsuya

    2014-08-01

    This study investigated whether wearing common white sportswear can reduce heat stress more than being semi-nude during exercise of different intensities performed under radiant heat and wind conditions, such as a hot summer day. After a 20-min rest period, eight male subjects performed three 20 min sessions of cycling exercise at a load intensity of 20 % or 50 % of their peak oxygen uptake (VO2peak) in a room maintained at a wet bulb globe temperature (WBGT) of 28.7 ± 0.1 °C using two spot lights and a fan (0.8 m/s airflow). Subjects wore common white sportswear (WS) consisting of a long-sleeved shirt (45 % cotton and 55 % polyester) and short pants (100 % polyester), or only swimming pants (SP) under the semi-nude condition. The mean skin temperature (Tsk) was greater when subjects wore SP than WS under both the 20 % and 50 % exercise conditions. During the 50 % exercise, the rating of perceived exertion (RPE) and thermal sensation (TS), and the increases in esophageal temperature (ΔTes) and heart rate were significantly higher (Pheat storage (S), calculated from the changes in the mean body temperature (0.9Tes + 0.1 Tsk), was significantly lower in the WS trials than in the SP trials during the 20 min resting period before exercise session. However, S was similar between conditions during the 20 % exercise, but was greater in the WS than in the SP trials during 50 % exercise. These results suggest that, under conditions of radiant heat and wind at a WBGT greater than 28 °C, the heat stress associated with wearing common WS is similar to that of being semi-nude during light exercise, but was greater during moderate exercise, and the storage of body heat can be reduced by wearing WS during rest periods.

  9. 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...

  10. Reactive power control methods for improved reliability of wind power inverters under wind speed variations

    DEFF Research Database (Denmark)

    Ma, Ke; Liserre, Marco; Blaabjerg, Frede

    2012-01-01

    temperature fluctuation in the most stressed devices of 3L-NPC wind power inverter under severe wind speed variations can be significantly stabilized, and the reliability of the power converter can thereby be improved while the increased stress of the other devices in the same power converter......The thermal cycling of power switching devices may lead to failures that compromise the reliability of power converters. Wind Turbine Systems (WTS) are especially subject to severe thermal cycling which may be caused by the wind speed variations or power grid faults. This paper proposes a control...... method to relieve the thermal cycling of power switching devices under severe wind speed variations, by circulating reactive power among the parallel power converters in a WTS or among the WTS's in a wind park. The amount of reactive power is adjusted to limit the junction temperature fluctuation...

  11. The forming of a superconductor cable during the winding of a large toroidal field coil

    International Nuclear Information System (INIS)

    Messemer, G.; Zehlein, H.

    1984-01-01

    The feasible range for the tension force which acts on a superconductor cable during the winding of a large D-shaped toroidal field coil depends strongly on the mechanical properties of the cable, on the geometry of the winding pack and on the arrangement of the equipment. The upper limit is imposed by possible damage within the cable. The lower limit is set by the need to assure enough compaction and to overcome the friction forces between the layers. Within this 'corridor' optimal control of elastic prestresses is desirable: this may be chosen with regard to the residual stresses and/or the elastic springback after removal of the coil former. This paper presents a simplified elastica conductor model built by a finite chain of intervals with constant bending moment and curvature. This paper describes the discrete model as well as the iterative shooting method, which finds the equilibrium shape of the conductor. The distributions of bending moment and shear forces around the D-shaped contour, as well as along the conductor, are given. Desirable improvements are outlined. In particular, the possibility of mitigating the stress concentration effect by supporting rollers suitably placed along the 'free' conductor near the bobbin is discussed. (author)

  12. Imposed work of breathing during high-frequency oscillatory ventilation : a bench study

    NARCIS (Netherlands)

    van Heerde, Marc; van Genderingen, Huib R.; Leenhoven, Tom; Roubik, Karel; Ploetz, Frans B.; Markhorst, Dick G.

    2006-01-01

    Introduction The ventilator and the endotracheal tube impose additional workload in mechanically ventilated patients breathing spontaneously. The total work of breathing (WOB) includes elastic and resistive work. In a bench test we assessed the imposed WOB using 3100 A/3100 B SensorMedics

  13. 42 CFR 422.756 - Procedures for imposing intermediate sanctions and civil money penalties.

    Science.gov (United States)

    2010-10-01

    ... instances where marketing or enrollment or both intermediate sanctions have been imposed, CMS may require an... assist CMS in making a determination as to whether the deficiencies that are the bases for the....752(c)(1), CMS will send a written notice of the Agency's decision to impose a civil money penalty to...

  14. 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

  15. 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)

  16. Adhesive Joints in Wind Turbine Blades

    DEFF Research Database (Denmark)

    Jørgensen, Jeppe Bjørn

    The industrial goal of this PhD project is to enable manufacturing of larger wind turbine blades by improving the existing design methods for adhesive joints. This should improve the present joint design such that more efficient wind turbine blades can be produced. The main scientific goal...... of the project is to develop new- and to improve the existing design rules for adhesive joints in wind turbine blades. The first scientific studies of adhesive joints were based on stress analysis, which requires that the bond-line is free of defects, but this is rarely the case for a wind turbine blade. Instead...... curing and test temperatures) on the formation of transverse cracks in the adhesive were tested experimentally. It was assumed that the transverse cracks evolved due to a combination of mechanical- and residual stresses in the adhesive. A new approach was developed that allows the residual stress...

  17. Assessment approaches to logistics for offshore wind energy installation

    NARCIS (Netherlands)

    Vis, Iris F.A.; Ursavas, Evrim

    2016-01-01

    Offshore wind farm installation planning is highly complex, due to the high dependency on weather and the oversized components that impose specific constraints in areas such as transportation and lifting. Currently, there is very little transparency vis-à-vis the logistics challenges in the

  18. 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.

  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. Crop yield response to deficit irrigation imposed at different plant growth stages

    International Nuclear Information System (INIS)

    Kovaks, T.; Kovaks, G.; Szito, J.

    1995-01-01

    A series of field experiments were conducted between 1991 - 1994 using 7 irrigation treatments at two fertilizer levels. Nitrogen fertilizers used were labelled with 15 N stable isotope to examine the effect of irrigation on the fertilizer N use efficiency by isotope technique. The irrigation were maintained at four different growth stages of maize, soybean and potato( vegetative, flowering, yield formation and ripening ) in 4 replicates. The aim of study was to compare deficit irrigation( i.e. the water stress imposed, during one growth stage ) with normal irrigation practice included the traditional one. Two watering regimes were established : (1) normal watering when available water was within the range of 60 - 90 %, and (2) deficit irrigation, when the AW was at 30 to 60 %. Neutron probe was used for measuring the soil water status and evaporation data were recorded to determine the amount of irrigation water demand. Reference evapotranspiration ( ETo) was calculated according to Penman - Monteith. Crop water requirement ( ETm) were determined in every year. Actual evapotranspiration ( ETa) was computed using CROPWAT: FAO computer program for irrigation planning and management (1992). Every irrigation treatment was equipped with neutron access tubes in two replicates at a depth from 10 to 130 cm. tensiometers were installed at depths of 30, 50, 60 and 80 cm in one replicate of treatments and were measured on a daily basis while neutron probe measurements were used to monitor the soil water table fluctuations. The irrigation method used was a special type of low pressure drop irrigation. There were measured the amount of rainfall with irrigation water supplied and the moisture distribution profiles were drown for the different treatments. Relationships between relative yield decrease and evapotranspiration and also between the crop yield and water use were determined. 9 tabs, 9 refs, ( Author )

  1. 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…

  2. 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…

  3. Smoothing of wind farm output power using prediction based flywheel energy storage system

    Science.gov (United States)

    Islam, Farzana

    Being socially beneficial, economically competitive and environment friendly, wind energy is now considered to be the world's fastest growing renewable energy source. However, the stochastic nature of wind imposes a considerable challenge in the optimal management and operation of wind power system. Wind speed prediction is critical for wind energy conversion system since it greatly influences the issues related to effective energy management, dynamic control of wind turbine, and improvement of the overall efficiency of the power generation system. This thesis focuses on integration of energy storage system with wind farm, considering wind speed prediction in the control scheme to overcome the problems associated with wind power fluctuations. In this thesis, flywheel energy storage system (FESS) with adjustable speed rotary machine has been considered for smoothing of output power in a wind farm composed of a fixed speed wind turbine generator (FSWTG). Since FESS has both active and reactive power compensation ability, it enhances the stability of the system effectively. An efficient energy management system combined with supervisory control unit (SCU) for FESS and wind speed prediction has been developed to improve the smoothing of the wind farm output effectively. Wind speed prediction model is developed by artificial neural network (ANN) which has advantages over the conventional prediction scheme including data error tolerance and ease in adaptability. The model for prediction with ANN is developed in MATLAB/Simulink and interfaced with PSCAD/EMTDC. Effectiveness of the proposed control system is illustrated using real wind speed data in various operating conditions.

  4. 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.

  5. 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,...

  6. 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

  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. 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....

  9. 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 ...

  10. Differences in the heat stress associated with white sportswear and being semi-nude in exercising humans under conditions of radiant heat and wind at a wet bulb globe temperature of greater than 28 °C

    Science.gov (United States)

    Tsuji, Michio; Kume, Masashi; Tuneoka, Hideyuki; Yoshida, Tetsuya

    2014-08-01

    This study investigated whether wearing common white sportswear can reduce heat stress more than being semi-nude during exercise of different intensities performed under radiant heat and wind conditions, such as a hot summer day. After a 20-min rest period, eight male subjects performed three 20 min sessions of cycling exercise at a load intensity of 20 % or 50 % of their peak oxygen uptake (VO2peak) in a room maintained at a wet bulb globe temperature (WBGT) of 28.7 ± 0.1 °C using two spot lights and a fan (0.8 m/s airflow). Subjects wore common white sportswear (WS) consisting of a long-sleeved shirt (45 % cotton and 55 % polyester) and short pants (100 % polyester), or only swimming pants (SP) under the semi-nude condition. The mean skin temperature was greater when subjects wore SP than WS under both the 20 % and 50 % exercise conditions. During the 50 % exercise, the rating of perceived exertion (RPE) and thermal sensation (TS), and the increases in esophageal temperature (ΔTes) and heart rate were significantly higher ( P < 0.001-0.05), or tended to be higher ( P < 0.07), in the WS than SP trials at the end of the third 20-min exercise session. The total sweat loss ( m sw,tot) was also significantly higher in the WS than in the SP trials ( P < 0.05). However, during the 20 % exercise, the m sw,tot during exercise, and the ΔTes, RPE and TS at the end of the second and third sessions of exercise did not differ significant between conditions. The heat storage (S), calculated from the changes in the mean body temperature (0.9Tes + 0.1 ), was significantly lower in the WS trials than in the SP trials during the 20 min resting period before exercise session. However, S was similar between conditions during the 20 % exercise, but was greater in the WS than in the SP trials during 50 % exercise. These results suggest that, under conditions of radiant heat and wind at a WBGT greater than 28 °C, the heat stress associated with wearing common WS is similar to that

  11. 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

  12. 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.

  13. 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.

  14. Wind Tunnel Tests of Parabolic Trough Solar Collectors: March 2001--August 2003

    Energy Technology Data Exchange (ETDEWEB)

    Hosoya, N.; Peterka, J. A.; Gee, R. C.; Kearney, D.

    2008-05-01

    Conducted extensive wind-tunnel tests on parabolic trough solar collectors to determine practical wind loads applicable to structural design for stress and deformation, and local component design for concentrator reflectors.

  15. The Offshore New European Wind Atlas

    Science.gov (United States)

    Karagali, I.; Hahmann, A. N.; Badger, M.; Hasager, C.; Mann, J.

    2017-12-01

    The New European Wind Atlas (NEWA) is a joint effort of research agencies from eight European countries, co-funded under the ERANET Plus Program. The project is structured around two areas of work: development of dynamical downscaling methodologies and measurement campaigns to validate these methodologies, leading to the creation and publication of a European wind atlas in electronic form. This atlas will contain an offshore component extending 100 km from the European coasts. To achieve this, mesoscale models along with various observational datasets are utilised. Scanning lidars located at the coastline were used to compare the coastal wind gradient reproduced by the meso-scale model. Currently, an experimental campaign is occurring in the Baltic Sea, with a lidar located in a commercial ship sailing from Germany to Lithuania, thus covering the entire span of the south Baltic basin. In addition, satellite wind retrievals from scatterometers and Synthetic Aperture Radar (SAR) instruments were used to generate mean wind field maps and validate offshore modelled wind fields and identify the optimal model set-up parameters.The aim of this study is to compare the initial outputs from the offshore wind atlas produced by the Weather & Research Forecasting (WRF) model, still in pre-operational phase, and the METOP-A/B Advanced Scatterometer (ASCAT) wind fields, reprocessed to stress equivalent winds at 10m. Different experiments were set-up to evaluate the model sensitivity for the various domains covered by the NEWA offshore atlas. ASCAT winds were utilised to assess the performance of the WRF offshore atlases. In addition, ASCAT winds were used to create an offshore atlas covering the years 2007 to 2016, capturing the signature of various spatial wind features, such as channelling and lee effects from complex coastal topographical elements.

  16. 'Wind turbine syndrome': fact or fiction?

    Science.gov (United States)

    Farboud, A; Crunkhorn, R; Trinidade, A

    2013-03-01

    Symptoms, including tinnitus, ear pain and vertigo, have been reported following exposure to wind turbine noise. This review addresses the effects of infrasound and low frequency noise and questions the existence of 'wind turbine syndrome'. This review is based on a search for articles published within the last 10 years, conducted using the PubMed database and Google Scholar search engine, which included in their title or abstract the terms 'wind turbine', 'infrasound' or 'low frequency noise'. There is evidence that infrasound has a physiological effect on the ear. Until this effect is fully understood, it is impossible to conclude that wind turbine noise does not cause any of the symptoms described. However, many believe that these symptoms are related largely to the stress caused by unwanted noise exposure. There is some evidence of symptoms in patients exposed to wind turbine noise. The effects of infrasound require further investigation.

  17. 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

  18. 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.)

  19. 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...

  20. Stress in plants cultured in vitro

    NARCIS (Netherlands)

    Klerk, de G.J.M.

    2007-01-01

    Plants subjected to stress display various defense mechanisms. On base of these mechanisms, stress-protective measures can be developed. This paper deals with protection brought about by putrescine. An in vitro system to impose drought stress was developed and the protective effect of putrescine on

  1. Tributes imposed on tourists as a new-old source of local governments income

    Directory of Open Access Journals (Sweden)

    Marcin BURZEC

    2014-12-01

    Full Text Available The growth in a number of tourists and, consequently, a larger income obtained from tourism by the state led to the situation when the previously marginalized tributes imposed on tourists by local governments have assumed greater significance. Additional revenues to local units’ budgets, gained from the above-mentioned tributes, are often allotted for better infrastructure and tourist promotion, thereby contributing to the increased tourist competitiveness. The present paper discusses the construction of levies imposed on tourists by local governments in various European states. Besides, the issues of how local governments can influence the construction of the tax within the frames of the granted tax autonomy are examined. Due to the fact that in many European countries burdens imposed on tourists by local units can be called taxes, fees or other levies, the term „tribute”, as a broader one including all statutory charges, is intentionally used in the present paper.

  2. 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.

  3. Microscopic Symmetry Imposed by Rotational Symmetry Boundary Conditions in Molecular Dynamics Simulation

    Science.gov (United States)

    Roy, Amitava; Post, Carol Beth

    2011-01-01

    A large number of viral capsids, as well as other macromolecular assemblies, have icosahedral structure or structures with other rotational symmetries. This symmetry can be exploited during molecular dynamics (MD) to model in effect the full viral capsid using only a subset of primary atoms plus copies of image atoms generated from rotational symmetry boundary conditions (RSBC). A pure rotational symmetry operation results in both primary and image atoms at short range, and within nonbonded interaction distance of each other, so that nonbonded interactions can not be specified by the minimum image convention and explicit treatment of image atoms is required. As such an unavoidable consequence of RSBC is that the enumeration of nonbonded interactions in regions surrounding certain rotational axes must include both a primary atom and its copied image atom, thereby imposing microscopic symmetry for some forces. We examined the possibility of artifacts arising from this imposed microscopic symmetry of RSBC using two simulation systems: a water shell and human rhinovirus 14 (HRV14) capsid with explicit water. The primary unit was a pentamer of the icosahedron, which has the advantage of direct comparison of icosahedrally equivalent spatial regions, for example regions near a 2-fold symmetry axis with imposed symmetry and a 2-fold axis without imposed symmetry. Analysis of structural and dynamic properties of water molecules and protein atoms found similar behavior near symmetry axes with imposed symmetry and where the minimum image convention fails compared with that in other regions in the simulation system, even though an excluded volume effect was detected for water molecules near the axes with imposed symmetry. These results validate the use of RSBC for icosahedral viral capsids or other rotationally symmetric systems. PMID:22096451

  4. Extended onshore control of a floating wind turbine with wave disturbance reduction

    DEFF Research Database (Denmark)

    Christiansen, S.; Knudsen, T.; Bak, Thomas

    2014-01-01

    Reaching for higher wind resources floating wind turbines are being investigated. Wave induced loads significantly increase for floating wind turbines, and applying conventional onshore control strategies to floating wind turbines has been shown to impose negative damped oscillations in fore......-aft due to the low natural frequency of the floating structure. We suggest a control loop extension of the onshore controller which stabilizes the system and reduces the wave disturbance. The result is improved performance in power fluctuations, blade pitch activity, and platform oscillations...

  5. Field measurement of wind pressure and wind-induced vibration of large-span spatial cable-truss system under strong wind or typhoon

    Directory of Open Access Journals (Sweden)

    ZHANG Zhihong

    2013-10-01

    Full Text Available In order to ensure wind-resistance safety of large-span pre-stressed flexible system in southeast coast area of China,and to prepare something for revising of current codes of practice or technical standards,the present paper conducts field measurement of wind pressure and wind-induced vibration of a practical and typical large-span spatial cable-truss system-lunar stadium in Yueqing city.Wind loading and wind effects on full-scale structure under strong wind or typhoon in real architectural environment can be obtained directly and effectively.Field measurement is the best way to investigate the wind loading property,wind effects,and wind-structure interactions of large-span flexible system.Measured data will be highly valuable for scientific research and practical design.On the other hand,it also provides the basis of wind-resistance safety design of this kind of tension structures.If any creative development,it would dramatically improve the research level of large-span pre-stressed flexible system in our country.

  6. Wind Turbines and Human Health

    Science.gov (United States)

    Knopper, Loren D.; Ollson, Christopher A.; McCallum, Lindsay C.; Whitfield Aslund, Melissa L.; Berger, Robert G.; Souweine, Kathleen; McDaniel, Mary

    2014-01-01

    The association between wind turbines and health effects is highly debated. Some argue that reported health effects are related to wind turbine operation [electromagnetic fields (EMF), shadow flicker, audible noise, low-frequency noise, infrasound]. Others suggest that when turbines are sited correctly, effects are more likely attributable to a number of subjective variables that result in an annoyed/stressed state. In this review, we provide a bibliographic-like summary and analysis of the science around this issue specifically in terms of noise (including audible, low-frequency noise, and infrasound), EMF, and shadow flicker. Now there are roughly 60 scientific peer-reviewed articles on this issue. The available scientific evidence suggests that EMF, shadow flicker, low-frequency noise, and infrasound from wind turbines are not likely to affect human health; some studies have found that audible noise from wind turbines can be annoying to some. Annoyance may be associated with some self-reported health effects (e.g., sleep disturbance) especially at sound pressure levels >40 dB(A). Because environmental noise above certain levels is a recognized factor in a number of health issues, siting restrictions have been implemented in many jurisdictions to limit noise exposure. These setbacks should help alleviate annoyance from noise. Subjective variables (attitudes and expectations) are also linked to annoyance and have the potential to facilitate other health complaints via the nocebo effect. Therefore, it is possible that a segment of the population may remain annoyed (or report other health impacts) even when noise limits are enforced. Based on the findings and scientific merit of the available studies, the weight of evidence suggests that when sited properly, wind turbines are not related to adverse health. Stemming from this review, we provide a number of recommended best practices for wind turbine development in the context of human health. PMID:24995266

  7. Wind turbines and human health.

    Science.gov (United States)

    Knopper, Loren D; Ollson, Christopher A; McCallum, Lindsay C; Whitfield Aslund, Melissa L; Berger, Robert G; Souweine, Kathleen; McDaniel, Mary

    2014-01-01

    The association between wind turbines and health effects is highly debated. Some argue that reported health effects are related to wind turbine operation [electromagnetic fields (EMF), shadow flicker, audible noise, low-frequency noise, infrasound]. Others suggest that when turbines are sited correctly, effects are more likely attributable to a number of subjective variables that result in an annoyed/stressed state. In this review, we provide a bibliographic-like summary and analysis of the science around this issue specifically in terms of noise (including audible, low-frequency noise, and infrasound), EMF, and shadow flicker. Now there are roughly 60 scientific peer-reviewed articles on this issue. The available scientific evidence suggests that EMF, shadow flicker, low-frequency noise, and infrasound from wind turbines are not likely to affect human health; some studies have found that audible noise from wind turbines can be annoying to some. Annoyance may be associated with some self-reported health effects (e.g., sleep disturbance) especially at sound pressure levels >40 dB(A). Because environmental noise above certain levels is a recognized factor in a number of health issues, siting restrictions have been implemented in many jurisdictions to limit noise exposure. These setbacks should help alleviate annoyance from noise. Subjective variables (attitudes and expectations) are also linked to annoyance and have the potential to facilitate other health complaints via the nocebo effect. Therefore, it is possible that a segment of the population may remain annoyed (or report other health impacts) even when noise limits are enforced. Based on the findings and scientific merit of the available studies, the weight of evidence suggests that when sited properly, wind turbines are not related to adverse health. Stemming from this review, we provide a number of recommended best practices for wind turbine development in the context of human health.

  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. The CMEMS L3 scatterometer wind product

    Science.gov (United States)

    de Kloe, Jos; Stoffelen, Ad; Verhoef, Anton

    2017-04-01

    Within the Copernicus Marine Environment Monitoring Service KNMI produces several ocean surface Level 3 wind products. These are daily updated global maps on a regular grid of the available scatterometer wind observations and derived properties, and produced from our EUMETSAT Ocean and Sea Ice Satellite Application Facility (OSI SAF) operational near-real time (NRT) Level 2 swath-based wind products by linear interpolation. Currently available products are the ASCAT on Metop A/B stress equivalent wind vectors, accompanied by ECMWF NWP reference stress equivalent winds from the operational ECMWF NWP model. For each ASCAT scatterometer we provide products on 2 different resolutions, 0.25 and 0.125 degrees. In addition we provide wind stress vectors, and derivative fields (curl and divergence) for stress equivalent wind and wind stress, both for the observations and for the NWP reference winds. New NRT scatterometer products will be made available when additional scatterometer instruments become available, and NRT access to the data can be arranged. We hope OSCAT on the Indian ScatSat-1 satellite will be the the next NRT product to be added. In addition multi-year reprocessing datasets have been made available for ASCAT on Metop-A (1-Jan-2007 up to 31-Mar-2014) and Seawinds on QuikScat (19-Jul-1999 up to 21-Nov-2009). For ASCAT 0.25 and 0.125 degree resolution products are provided, and for QuikScat 0.50 and 0.25 degree resolution products are provided, These products are based on reprocessing the L2 scatterometer products with the latest processing software version, and include reference winds from the ECMWF ERA-Interim model. Additional reprocessing datasets will be added when reprocessed L2 datasets become available. This will hopefully include the ERS-1 and ERS-2 scatterometer datasets (1992-2001), which will extend the available date range back to 1992. These products are available for download through the CMEMS portal website: http://marine.copernicus.eu/

  10. Price volatility in wind dominant electricity markets

    DEFF Research Database (Denmark)

    Farashbashi-Astaneh, Seyed-Mostafa; Chen, Zhe

    2013-01-01

    High penetration of intermittent renewable energy sources causes price volatility in future electricity markets. This is specially the case in European countries that plan high penetration levels. This highlights the necessity for revising market regulations and mechanisms in accordance...... electricity markets. High price volatility is unappreciated because it imposes high financial risk levels to both electricity consumers and producers. Additionally high price variations impede tracking price signals by consumers in future smart grid and jeopardize implementation of demand response concepts....... The main contribution of this paper is to quantify volatility patterns of electricity price, as penetration level of wind power increases. Results explain a direct relationship between wind penetration and electricity price volatility in a quantitative manner....

  11. 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

  12. Unsustainable Wind Turbine Blade Disposal Practices in the United States.

    Science.gov (United States)

    Ramirez-Tejeda, Katerin; Turcotte, David A; Pike, Sarah

    2017-02-01

    Finding ways to manage the waste from the expected high number of wind turbine blades in need of disposal is crucial to harvest wind energy in a truly sustainable manner. Landfilling is the most cost-effective disposal method in the United States, but it imposes significant environmental impacts. Thermal, mechanical, and chemical processes allow for some energy and/or material recovery, but they also carry potential negative externalities. This article explores the main economic and environmental issues with various wind turbine blade disposal methods. We argue for the necessity of policy intervention that encourages industry to develop better technologies to make wind turbine blade disposal sustainable, both environmentally and economically. We present some of the technological initiatives being researched, such as the use of bio-derived resins and thermoplastic composites in the manufacturing process of the blades.

  13. 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...

  14. 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...

  15. Characterization of eucalyptus clones subject to wind damage

    OpenAIRE

    Zanuncio, Antônio José Vinha; Carvalho, Amélia Guimarães; Carneiro, Angélica de Cassia Oliveira; Valenzuela, Paulina; Gacitúa, William; Leite, Fernando Palha; Colodette, Jorge Luiz

    2017-01-01

    Abstract: The objective of this work was to test a new methodology to assess the resistance of trees to wind damage and determine the characteristics that increase clone resistance to winds. Tree resistance to breakage, basic density, ultrastructure, anatomy, mechanical properties, and wood growth stress have been evaluated in seven Eucalyptus grandis × Eucalyptus urophylla clones, collected from a region with a high incidence of wind damage. The Pearson correlation coefficient between the tr...

  16. 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...

  17. 20 CFR 655.1230 - What time limits are imposed in ALJ proceedings?

    Science.gov (United States)

    2010-04-01

    ... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false What time limits are imposed in ALJ proceedings? 655.1230 Section 655.1230 Employees' Benefits EMPLOYMENT AND TRAINING ADMINISTRATION, DEPARTMENT... direct the parties to serve pleadings or documents by a method other than regular mail. (b) Two (2...

  18. Special economic zones as an instrument to enhance international cooperation in the economic conditions imposed sanctions

    OpenAIRE

    BURTSEVA TATIANA; SHUGAR VALERIYA

    2015-01-01

    The article considers the role of special economic zones in the conditions imposed sanctions. We analyzed the number of residents, including foreign ones, as well as the amount of their investment. We studied the special economic zones of tourist-type as a tool to enhance the attractiveness of the country and the region in particular.

  19. CJEU rules on use of standards in imposing information duties on life insurance companies

    NARCIS (Netherlands)

    Mańko, R.

    2015-01-01

    The EU Directive applicable to life insurance sets out what kind of information insurance companies must give to policyholders. It also allows Member States to impose broader information duties, provided that the information is necessary for the policyholder to understand the contract. In its ruling

  20. ENTRAINMENT OF THE BREATHING RHYTHM OF THE CARP BY IMPOSED OSCILLATION OF THE GILL ARCHES

    NARCIS (Netherlands)

    DEGRAAF, PJF; ROBERTS, BL

    Artificial oscillation imposed onto the gill arches could modify the respiratory rhythm in the carp Cyprinus carpio. The degree of modification depended upon the frequency and amplitude of the applied movement. Oscillation at frequencies close to the spontaneous respiratory rhythm and at amplitudes

  1. 76 FR 74690 - Extension of Import Restrictions Imposed on Archaeological and Ethnological Material From Bolivia

    Science.gov (United States)

    2011-12-01

    ... with Bolivia on December 4, 2001, concerning the imposition of import restrictions on certain... CFR Part 12 [CBP Dec. 11-24] RIN 1515-AD83 Extension of Import Restrictions Imposed on Archaeological and Ethnological Material From Bolivia AGENCY: U.S. Customs and Border Protection; Department of...

  2. Identification during imposed change: the roles of personal values, type of change, and anxiety.

    Science.gov (United States)

    Sverdlik, Noga; Oreg, Shaul

    2015-06-01

    Using a person-situation perspective, we explain what happens to individuals' identification with a collective in the context of a change. We propose that given the anxiety that often emerges during change, individuals' personal values (conservation and openness to change) interact with type of change (imposed vs. voluntary) in predicting identification following change. In a pilot, longitudinal field study (N = 61, 67% female) of an imposed university campus relocation, we measured employees' values and identification with the university before and several months after the relocation. In two lab experiments (Study 1: N = 104, 91.3% female; Study 2: N = 113, 75.2% female), we manipulated a change to be either imposed or voluntary and compared the relationships between values and identification across types of change. In Study 2, we also measured anxiety from the change. When change was imposed (all three studies), but not when voluntary (Studies 1 and 2), individuals' conservation was positively, and openness negatively, related to individuals' post-change identification. The effects emerged only for individuals who experienced change-related anxiety (Study 2). Our findings demonstrate that individuals' identification with a changing collective depends on the amount of anxiety change elicits and on the particular combination of their values and type of change. © 2014 Wiley Periodicals, Inc.

  3. 42 CFR 423.756 - Procedures for imposing intermediate sanctions and civil money penalties.

    Science.gov (United States)

    2010-10-01

    ... independent review has been performed. (ii) In instances where marketing or enrollment or both intermediate... both for a limited period of time in order to assist CMS in making a determination as to whether the... decision to impose a civil money penalty to include— (i) A description of the basis for the determination...

  4. 13 CFR 127.700 - What penalties may be imposed under this part?

    Science.gov (United States)

    2010-01-01

    ... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false What penalties may be imposed under this part? 127.700 Section 127.700 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION WOMEN-OWNED SMALL BUSINESS FEDERAL CONTRACT ASSISTANCE PROCEDURES Penalties § 127.700 What penalties may...

  5. Are the force characteristics of synchronous handcycling affected by speed and the method to impose power?

    NARCIS (Netherlands)

    Arnet, U.; van Drongelen, S.V.; van der Woude, L.H.V.; Veeger, H.E.J.

    2012-01-01

    Objective: To investigate the influence of exercise conditions (speed and method to impose power) on the applied force, force effectiveness and distribution of work during handcycling. Method: Ten able-bodied men performed handcycling on a treadmill. To test the effect of speed, subjects propelled

  6. Are the force characteristics of synchronous handcycling affected by speed and the method to impose power?

    NARCIS (Netherlands)

    Arnet, Ursina; van Drongelen, Stefan; Veeger, DirkJan H. E. J.; van der Woude, Lucas H. V.

    Objective: To investigate the influence of exercise conditions (speed and method to impose power) on the applied force, force effectiveness and distribution of work during handcycling. Method: Ten able-bodied men performed handcycling on a treadmill. To test the effect of speed, subjects propelled

  7. Adolescent Drug Use and the Deterrent Effect of School-Imposed Penalties

    Science.gov (United States)

    Waddell, G. R.

    2012-01-01

    Estimates of the effect of school-imposed penalties for drug use on a student's consumption of marijuana are biased if both are determined by unobservable school or individual attributes. Reverse causality is also a potential challenge to retrieving estimates of the causal relationship, as the severity of school sanctions may simply reflect the…

  8. Offshore wind energy developments

    DEFF Research Database (Denmark)

    Stolpe, Mathias; Buhl, Thomas; Sumer, B. Mutlu

    2014-01-01

    This chapter will give a brief overview of a few of the activities within offshore wind energy research, specifically 1) Support structure optimization, 2) Blade coatings for wind turbines; 3) Scour protection of foundations, 4) Offshore HVDC and 5) Offshore wind services.......This chapter will give a brief overview of a few of the activities within offshore wind energy research, specifically 1) Support structure optimization, 2) Blade coatings for wind turbines; 3) Scour protection of foundations, 4) Offshore HVDC and 5) Offshore wind services....

  9. Wind energy information guide

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-04-01

    This book is divided into nine chapters. Chapters 1--8 provide background and annotated references on wind energy research, development, and commercialization. Chapter 9 lists additional sources of printed information and relevant organizations. Four indices provide alphabetical access to authors, organizations, computer models and design tools, and subjects. A list of abbreviations and acronyms is also included. Chapter topics include: introduction; economics of using wind energy; wind energy resources; wind turbine design, development, and testing; applications; environmental issues of wind power; institutional issues; and wind energy systems development.

  10. Wind Power Career Chat

    Energy Technology Data Exchange (ETDEWEB)

    2011-01-01

    This document will teach students about careers in the wind energy industry. Wind energy, both land-based and offshore, is expected to provide thousands of new jobs in the next several decades. Wind energy companies are growing rapidly to meet America's demand for clean, renewable, and domestic energy. These companies need skilled professionals. Wind power careers will require educated people from a variety of areas. Trained and qualified workers manufacture, construct, operate, and manage wind energy facilities. The nation will also need skilled researchers, scientists, and engineers to plan and develop the next generation of wind energy technologies.

  11. Arctic wind energy

    International Nuclear Information System (INIS)

    Peltola, E.; Holttinen, H.; Marjaniemi, M.; Tammelin, B.

    1998-01-01

    Arctic wind energy research was aimed at adapting existing wind technologies to suit the arctic climatic conditions in Lapland. Project research work included meteorological measurements, instrument development, development of a blade heating system for wind turbines, load measurements and modelling of ice induced loads on wind turbines, together with the development of operation and maintenance practices in arctic conditions. As a result the basis now exists for technically feasible and economically viable wind energy production in Lapland. New and marketable products, such as blade heating systems for wind turbines and meteorological sensors for arctic conditions, with substantial export potential, have also been developed. (orig.)

  12. Arctic wind energy

    Energy Technology Data Exchange (ETDEWEB)

    Peltola, E. [Kemijoki Oy (Finland); Holttinen, H.; Marjaniemi, M. [VTT Energy, Espoo (Finland); Tammelin, B. [Finnish Meteorological Institute, Helsinki (Finland)

    1998-12-31

    Arctic wind energy research was aimed at adapting existing wind technologies to suit the arctic climatic conditions in Lapland. Project research work included meteorological measurements, instrument development, development of a blade heating system for wind turbines, load measurements and modelling of ice induced loads on wind turbines, together with the development of operation and maintenance practices in arctic conditions. As a result the basis now exists for technically feasible and economically viable wind energy production in Lapland. New and marketable products, such as blade heating systems for wind turbines and meteorological sensors for arctic conditions, with substantial export potential, have also been developed. (orig.)

  13. Wind power today

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-04-01

    This publication highlights initiatives of the US DOE`s Wind Energy Program. 1997 yearly activities are also very briefly summarized. The first article describes a 6-megawatt wind power plant installed in Vermont. Another article summarizes technical advances in wind turbine technology, and describes next-generation utility and small wind turbines in the planning stages. A village power project in Alaska using three 50-kilowatt turbines is described. Very brief summaries of the Federal Wind Energy Program and the National Wind Technology Center are also included in the publication.

  14. Analysis of federally imposed penalties for violations of the Consolidated Omnibus Reconciliation Act.

    Science.gov (United States)

    Levine, R J; Guisto, J A; Meislin, H W; Spaite, D W

    1996-07-01

    To identify the incidence of federally imposed penalties for violations of the Consolidated Omnibus Reconciliation Act (COBRA). Under the Freedom of Information Act, we retrieved a copy of any document related to fines imposed on, settlements made by, or litigation against physicians or hospitals as a result of COBRA violations from the Office of the Inspector General. Under a separate inquiry, also under the Freedom of Information Act, we requested and received from the central office of the Health Care Financing Administration the National Composite Log showing the status of all complaint investigations pursuant to COBRA since the inception of the law. One thousand seven hundred fifty-seven complaint investigations were authorized. Of the 1,729 investigations completed, 412 (24%) were found to be out of compliance with federal regulations. Of these, 27 cases resulted in fines imposed on hospitals. These fines ranged from $1,500 to $150,000 with a mean of $33,917, a median of $25,000, and standard deviation of $35,899. The six fines that were imposed against physicians ranged in value from $2,500 to $20,000 with a mean of $8,500, a median of $7,500, and an SD of $8,612. Seven hospitals but no physicians were terminated from the Medicare program for COBRA violations. The incidence of federally imposed penalties for COBRA violations is low given the multitude of patient transfers that have occurred since the enactment of COBRA. The growing concern regarding this issue may be related to current litigation efforts to broaden the scope and applications of these laws.

  15. High Resolution Wind and SST Coupling: Impacts on Ekman Upwelling

    Science.gov (United States)

    Bourassa, M. A.; Hughes, P. J.

    2014-12-01

    Satellite observations have revealed a small-scale (air-sea coupling in regions of strong sea surface temperature (SST) fronts (e.g., currents, eddies, and tropical instability waves), where the surface wind and wind stress are altered by the underlying SST. Surface winds and wind stresses are persistently higher over the warm side of the SST front compared to the cool side, causing perturbations in the dynamically and thermodynamically curl and divergence fields. Capturing this small-scale SST-wind variability is important because it can significantly impact both local and remote (i.e., large scale) oceanic and atmospheric processes. The SST-wind relationship is not well represented in numerical weather prediction (NWP) and climate models, and the relative importance of the physical processes that are proposed to be responsible for this relationship is actively and vehemently debated. This study focuses on the physical mechanisms that are primarily responsible for the SST-induced changes in surface wind and wind stress, and on the physical implication on ocean forcing through Ekman pumping. This study shows that the baroclinic-related changes in Ekman pumping are significant (first-order) over a seasonal (2003 winter season) time scale and that the meso-scale impacts are quite important over larger spatial scales. These findings highlight the need to consider the small-scale SST-wind relationship even in coarser resolution model simulation, which may be feasible to parameterize because of the linear nature of the baroclinic-related effect.

  16. Wind Effects on Retention Time in Highway Ponds

    DEFF Research Database (Denmark)

    Bentzen, Thomas Ruby; Larsen, Torben; Rasmussen, Michael R.

    2007-01-01

    is to evaluate the quality of long term simulations based on historical rain series of the pollutant discharges from roads and highways. The idea of this paper is to evaluate the effects of wind on the retention time and compare the retention time for the situation of a spatial uniform wind shear stress...

  17. Wind Effects on Retention Time in Highway Ponds

    DEFF Research Database (Denmark)

    Bentzen, Thomas Ruby; Larsen, Torben; Rasmussen, Michael R.

    2008-01-01

    is to evaluate the quality of long term simulations based on historical rain series of the pollutant discharges from roads and highways. The idea of this paper is to evaluate the effects of wind on the retention time and compare the retention time for the situation of a spatial uniform wind shear stress...

  18. Advantages on monitoring wind turbine nacelle oscillation

    DEFF Research Database (Denmark)

    Skrimpas, Georgios Alexandros; Marhadi, Kun Saptohartyadi; Hilmisson, Reynir

    2015-01-01

    and vibrations on blades, tower and drive train components, which may jeopardize their working condition. The present paper deals with the comparison and analysis of vibration signals from wind turbines subjected to various failure modes and operating conditions, such as blade misalignment, pitch malfunction......, ice accretion, damaged blade tips and yaw system defects. Theoretical analysis of nacelle movement at down wind and lateral direction is presented along with field results from multi megawatt wind turbines. Additionally the paper discusses the employment of nacelle accelerometers for cross reference......Nacelle oscillation monitoring, where accelerometers are mounted on the nacelle frame, is integral part of modern condition monitoring systems towards holistic and consistent health assessment of wind turbines. It enables detection of abnormal behavior associated to increased stresses...

  19. Evolution of wind towards wind turbine

    NARCIS (Netherlands)

    Giyanani, A.H.; Bierbooms, W.A.A.M.; Van Bussel, G.J.W.

    2015-01-01

    Remote sensing of the atmospheric variables with the use of LiDAR is a relatively new technology field for wind resource assessment in wind energy. The validation of LiDAR measurements and comparisons is of high importance for further applications of the data.

  20. 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...

  1. Realization and control of a wind turbine connected to the grid by using PMSG

    International Nuclear Information System (INIS)

    Dahbi, Abdeldjalil; Hachemi, Mabrouk; Nait-Said, Nasreddine; Nait-Said, Mohamed-Said

    2014-01-01

    Highlights: • Realization and control of a wind turbine. • Control of the system. • Injection to grid. - Abstract: This paper studies the control of a variable-speed wind turbine using the permanent magnet synchronous generator (PMSG) driven by a wind turbine emulator. The wind turbine is realized by imposing the wind profile on emulator to behave as the real wind turbine when it receives the same wind profile. This wind turbine is connected to the grid by means of a two back-to-back voltage-fed pulse width-modulation (PWM) converters to interface the generator and the grid. This paper has three main objectives, the first is realization of the wind turbine emulator, the second is extracting and exploiting the maximum power from the wind, the third is feeding the grid by high-power and good electrical energy quality; to achieve that, we applied the strategies of maximum power point tracking (MPPT) using optimal torque control which allows the PMSG to operate at an optimal speed. The inverter is used for delivering power to the grid, controlled in a way to deliver only the active power into the grid, thus we have unit power factor. DC-link voltage is also controlled by the inverter. This paper shows the dynamic performances of the complete system by its simulation using Matlab Simulink. Experimental results has verified and validated the wind turbine emulator and the efficiency of MPPT control method using a variable wind profile

  2. The design of models for cryogenic wind tunnels. [mechanical properties and loads

    Science.gov (United States)

    Gillespie, V. P.

    1977-01-01

    Factors to be considered in the design and fabrication of models for cryogenic wind tunnels include high model loads imposed by the high operating pressures, the mechanical and thermodynamic properties of materials in low temperature environments, and the combination of aerodynamic loads with the thermal environment. Candidate materials are being investigated to establish criteria for cryogenic wind tunnel models and their installation. Data acquired from these tests will be provided to users of the National Transonic Facility.

  3. An evaluation of the WindEye wind lidar

    DEFF Research Database (Denmark)

    Dellwik, Ebba; Sjöholm, Mikael; Mann, Jakob

    Prevision of the wind field by remote sensing wind lidars has the potential to improve the performance of wind turbines. The functionality of a WindEye lidar developed by Windar Photonics A/S (Denmark) for the wind energy market was tested in a two months long field experiment. The WindEye sensor...... with a high accuracy during the whole campaign....

  4. Wind electric power generation

    International Nuclear Information System (INIS)

    Koch, M.K.; Wind, L.; Canter, B.; Moeller, T.

    2001-01-01

    The monthly statistics of wind electric power generation in Denmark are compiled from information given by the owners of the private wind turbines. For each wind turbine the name of the site and of the type of turbine is given, and the power generation data are given for the month in question together with the total production in 1999 and 2000. Also the data of operation start are given. On the map of Denmark the sites of the wind turbines are marked. (CLS)

  5. The Irish Wind Atlas

    Energy Technology Data Exchange (ETDEWEB)

    Watson, R. [Univ. College Dublin, Dept. of Electronic and Electrical Engineering, Dublin (Ireland); Landberg, L. [Risoe National Lab., Meteorology and Wind Energy Dept., Roskilde (Denmark)

    1999-03-01

    The development work on the Irish Wind Atlas is nearing completion. The Irish Wind Atlas is an updated improved version of the Irish section of the European Wind Atlas. A map of the irish wind resource based on a WA{sup s}P analysis of the measured data and station description of 27 measuring stations is presented. The results of previously presented WA{sup s}P/KAMM runs show good agreement with these results. (au)

  6. Turbulence and wind turbines

    DEFF Research Database (Denmark)

    Brand, Arno J.; Peinke, Joachim; Mann, Jakob

    2011-01-01

    The nature of turbulent flow towards, near and behind a wind turbine, the effect of turbulence on the electricity production and the mechanical loading of individual and clustered wind turbines, and some future issues are discussed.......The nature of turbulent flow towards, near and behind a wind turbine, the effect of turbulence on the electricity production and the mechanical loading of individual and clustered wind turbines, and some future issues are discussed....

  7. Wind Power Now!

    Science.gov (United States)

    Inglis, David Rittenhouse

    1975-01-01

    The government promotes and heavily subsidizes research in nuclear power plants. Federal development of wind power is slow in comparison even though much research with large wind-electric machines has already been conducted. Unless wind power programs are accelerated it will not become a major energy alternative to nuclear power. (MR)

  8. Power from the Wind

    Science.gov (United States)

    Roman, Harry T.

    2004-01-01

    Wind energy is the fastest-growing renewable energy source in the world. Over the last 20 years, the wind industry has done a very good job of engineering machines, improving materials, and economies of production, and making this energy source a reality. Like all renewable energy forms, wind energy's successful application is site specific. Also,…

  9. Extreme winds in Denmark

    DEFF Research Database (Denmark)

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

    1999-01-01

    Wind-speed data from four sites in Denmark have been analyzed in order to obtain estimates of the basic wind velocity, defined as the 50-year wind speed (ten minute averages) under standard conditions, i.e. 10 meter over a homogeneous terrain with the roughness length 0.05 m. The sites are Skjern...

  10. Extreme winds in Denmark

    DEFF Research Database (Denmark)

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

    1999-01-01

    Wind-speed data from four sites in Denmark have been analyzed in order to obtain estimates of the basic wind velocity which is defined as the 50-year wind speed under standard conditions, i.e. ten-minute averages at the height 10 m over a uniform terrainwith the roughness length 0.05 m. The sites...

  11. 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....

  12. 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....

  13. Wind power soars

    Energy Technology Data Exchange (ETDEWEB)

    Flavin, C. [Worldwatch Inst., Washington, DC (United States)

    1996-12-31

    Opinions on the world market for wind power are presented in this paper. Some data for global wind power generating capacity are provided. European and other markets are discussed individually. Estimated potential for wind power is given for a number of countries. 3 figs.

  14. Wind power outlook 2006

    Energy Technology Data Exchange (ETDEWEB)

    anon.

    2006-04-15

    This annual brochure provides the American Wind Energy Association's up-to-date assessment of the wind industry in the United States. This 2006 general assessment shows positive signs of growth, use and acceptance of wind energy as a vital component of the U.S. energy mix.

  15. 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...

  16. 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

  17. Denmark Wind Energy Programme

    DEFF Research Database (Denmark)

    Shen, Wen Zhong

    2015-01-01

    In this chapter, a summary of some ongoing wind energy projects in Denmark is given. The research topics comprise computational model development, wind turbine (WT) design, low-noise airfoil and blade design, control device development, wake modelling and wind farm layout optimization....

  18. Wind energy in Mediterranean Basin

    International Nuclear Information System (INIS)

    Gaudiosi, G.

    1991-01-01

    In its examination of wind energy potential in the Mediterranean Basin, this paper provides brief notes on the Basin's geography; indicates power production and demand; describes the area's wind characteristics and wind monitoring activities; illustrates wind velocity distributions; estimates local wind power production potential; reviews the Basin's wind energy marketing situation and each bordering country's wind energy programs; surveys installed wind energy farms; and assesses national research and commercialization efforts

  19. Ocean Ekman Response to Wind Forcing in Frontal Regions and Implications for Vertical Velocity

    Science.gov (United States)

    Cronin, M. F.; Tozuka, T.

    2016-12-01

    Wind forcing is fundamental to the ocean circulation. According to the classic "Ekman" theory developed in the early twentieth century, wind-induced steady flow spirals to the right of the wind stress in the Northern Hemisphere and to the left in the Southern Hemisphere, resulting in a net wind-forced "Ekman" transport that is 90 degrees to the right of the wind stress in the Northern Hemisphere and to the left in the Southern Hemisphere. This theory, however, assumes that the near-surface ocean is uniform in density (i.e., has no fronts). In frontal regions the surface "geostrophic" currents have a vertical shear aligned with the density front and this oceanic "thermal wind" shear can balance a portion of the surface wind stress. In this study we show that in frontal regions, the classic Ekman response is altered. Surface ocean currents respond to the effective wind stress—the portion of the wind stress that is out of balance with the ocean's surface geostrophic shear. Consequently, the vertical velocity at the base of the mixed layer is better approximated by the curl of the effective wind stress, rather than the full wind stress. Wind blowing along a front can give rise to a local minimum in the effective wind stress and result in a secondary circulation with downwelling on the cold side of the front and upwelling on the warm side. Using data from the high-resolution Japanese Ocean general circulation model For the Earth Simulator (OFES), we show that these frontal effects cannot be ignored in the Tropics or in strong frontal regions in the extratropics, such as found in coastal regions and in western boundary currents of all basins. Furthermore, these frontal effects dominate the classic Ekman response in regions of both hemispheres where trade winds change to westerlies.

  20. An electron plasma experiment to study vortex dynamics subject to externally imposed flows

    Science.gov (United States)

    Hurst, N. C.; Danielson, J. R.; Surko, C. M.

    2018-01-01

    An experimental technique is presented for studying two-dimensional (2D) ideal fluid vortices in the presence of externally imposed flows, using an electron plasma confined in a Penning-Malmberg trap. This procedure is made possible by an isomorphism between the Drift-Poisson equations governing electron plasma dynamics and the 2D Euler equations describing an ideal fluid. Here, the electron density is the analog of fluid vorticity, and the electric potential that of the fluid stream function. External flows are imposed in 2D using a segmented electrode spanning the length of the plasma. Details of the experimental procedure and data analysis are given, including the capabilities and limitations of the experimental approach.

  1. The cost of self-imposed regulatory burden in animal research.

    Science.gov (United States)

    Thulin, Joseph D; Bradfield, John F; Bergdall, Valerie K; Conour, Laura A; Grady, Andrew W; Hickman, Debra L; Norton, John N; Wallace, Jeanne M

    2014-08-01

    U.S. federal regulations and standards governing the care and use of research animals enacted in the mid- to late 1980s, while having positive effects on the welfare and quality of the animals, have resulted in dramatic increases in overall research costs. In addition to the expenses of housing and caring for animals according to the standards, establishing the requisite internal compliance bureaucracies has markedly driven up costs, in both institutional monetary expenditures and lost research effort. However, many institutions are increasing these costs even further through additional self-imposed regulatory burden, typically characterized by overly complex compliance organizations and unnecessary policies and procedures. We discuss the sources of this self-imposed burden and recommend strategies for avoiding it while preserving an appropriate focus on animal well-being and research success. © FASEB.

  2. Classification of Rotor Induced Shearing Events in the Near Wake of a Wind Turbine Array Boundary Layer

    Science.gov (United States)

    Smith, Sarah; Viggiano, Bianca; Ali, Naseem; Cal, Raul Bayoan

    2017-11-01

    Flow perturbation induced by a turbine rotor imposes considerable turbulence and shearing effects in the near wake of a turbine, altering the efficiency of subsequent units within a wind farm array. Previous methods have characterized near wake vorticity of a turbine and recovery distance of various turbine array configurations. This study aims to build on previous analysis with respect to a turbine rotor within an array and develop a model to examine stress events and energy contribution in the near wake due to rotational effects. Hot wire anemometry was employed downstream of a turbine centrally located in the third row of a 3x3 array. Data considered points planar to the rotor and included simultaneous streamwise and wall-normal velocities as well as concurrent streamwise and transverse velocities. Conditional analysis of Reynolds stresses induced by the rotor agree with former near wake research, and examination of stresses in terms of streamwise and transverse velocity components depicts areas of significant rotational effects. Continued analysis includes spectral decomposition and conditional statistics to further characterize shearing events at various points considering the swept area of the rotor.

  3. Endotracheal tubes and imposed work of breathing: what should we do about it, if anything?

    Science.gov (United States)

    Branson, Richard D

    2003-01-01

    Concerns about the work of breathing imposed by the endotracheal tube have led clinicians to routinely use pressure support to overcome this resistive component. More recently, ventilator manufacturers have introduced systems to automatically overcome endotracheal tube resistance, regardless of tube diameter or patient demand for flow. Despite the theoretical advantages, neither method appears to provide superior performance. Stepping back, the real question may be, is overcoming endotracheal tube resistance really important? PMID:12974965

  4. Minimax passband group delay nonlinear FIR filter design without imposing desired phase response

    OpenAIRE

    Ho, Charlotte Yuk-Fan; Ling, Wing-Kuen; Dam, Hai Huyen; Yeo, Kok-Lay

    2011-01-01

    In this paper, a nonlinear phase finite impulse response (FIR) filter is designed without imposing a desired phase response. The maximum passband group delay of the filter is minimized subject to a positivity constraint on the passband group delay response of the filter as well as a specification on the maximum absolute difference between the desired magnitude square response and the designed magnitude square response over both the passband and the stopband. This filter design problem is a no...

  5. Imposed Work of Breathing and Breathing Comfort of Nonintubated Volunteers Breathing with Three Portable Ventilators and a Critical Care Ventilator

    National Research Council Canada - National Science Library

    Austin, Paul

    2001-01-01

    .... The purpose of this study was to assess the imposed inspiratory work of breathing and breathing comfort of nonintubated healthy volunteers breathing spontaneously through three portable ventilators...

  6. Offshore wind resource estimation for wind energy

    DEFF Research Database (Denmark)

    Hasager, Charlotte Bay; Badger, Merete; Mouche, A.

    2010-01-01

    Satellite remote sensing from active and passive microwave instruments is used to estimate the offshore wind resource in the Northern European Seas in the EU-Norsewind project. The satellite data include 8 years of Envisat ASAR, 10 years of QuikSCAT, and 23 years of SSM/I. The satellite observati......Satellite remote sensing from active and passive microwave instruments is used to estimate the offshore wind resource in the Northern European Seas in the EU-Norsewind project. The satellite data include 8 years of Envisat ASAR, 10 years of QuikSCAT, and 23 years of SSM/I. The satellite...... observations are compared to selected offshore meteorological masts in the Baltic Sea and North Sea. The overall aim of the Norsewind project is a state-of-the-art wind atlas at 100 m height. The satellite winds are all valid at 10 m above sea level. Extrapolation to higher heights is a challenge. Mesoscale...... modeling of the winds at hub height will be compared to data from wind lidars observing at 100 m above sea level. Plans are also to compare mesoscale model results and satellite-based estimates of the offshore wind resource....

  7. Flexibly imposing periodicity in kernel independent FMM: A multipole-to-local operator approach

    Science.gov (United States)

    Yan, Wen; Shelley, Michael

    2018-02-01

    An important but missing component in the application of the kernel independent fast multipole method (KIFMM) is the capability for flexibly and efficiently imposing singly, doubly, and triply periodic boundary conditions. In most popular packages such periodicities are imposed with the hierarchical repetition of periodic boxes, which may give an incorrect answer due to the conditional convergence of some kernel sums. Here we present an efficient method to properly impose periodic boundary conditions using a near-far splitting scheme. The near-field contribution is directly calculated with the KIFMM method, while the far-field contribution is calculated with a multipole-to-local (M2L) operator which is independent of the source and target point distribution. The M2L operator is constructed with the far-field portion of the kernel function to generate the far-field contribution with the downward equivalent source points in KIFMM. This method guarantees the sum of the near-field & far-field converge pointwise to results satisfying periodicity and compatibility conditions. The computational cost of the far-field calculation observes the same O (N) complexity as FMM and is designed to be small by reusing the data computed by KIFMM for the near-field. The far-field calculations require no additional control parameters, and observes the same theoretical error bound as KIFMM. We present accuracy and timing test results for the Laplace kernel in singly periodic domains and the Stokes velocity kernel in doubly and triply periodic domains.

  8. Age and sex differences in steadiness of elbow flexor muscles with imposed cognitive demand

    Science.gov (United States)

    Pereira, Hugo M.; Spears, Vincent C.; Schlinder-Delap, Bonnie; Yoon, Tejin; Nielson, Kristy A.; Hunter, Sandra K.

    2015-01-01

    Purpose These studies determined (1) age and sex-related differences in steadiness of isometric contractions when high cognitive demand was imposed across a range of forces with the elbow flexor muscles (study 1) and, (2) sex differences in steadiness among older adults when low cognitive demand was imposed (study 2). Methods 36 young adults (18–25 years; 18 women) and 30 older adults (60–82 years; 17 women) performed isometric contractions at 5%, 30% and 40% of maximum voluntary contraction (MVC). Study 1 involved a high-cognitive demand session (serial subtractions by 13 during the contraction) and a control session (no mental math). Study 2 (older adults only) involved a low-cognitive demand session (subtracting by 1s). Results Older individuals exhibited greater increases in force fluctuations (coefficient of variation of force, CV) with high cognitive demand than young adults, with the largest age difference at 5% MVC (P = 0.01). Older adults had greater agonist EMG activity with high-cognitive demand and women had greater coactivation than men (Pdemand for the older women but not for the older men (P = 0.03). Conclusion Older adults had reduced steadiness and increased muscle activation when high cognitive demand was imposed while low cognitive demand induced increased force fluctuations in older women but not older men. These findings have implications for daily and work-related tasks that involve cognitive demand performed simultaneously during submaximal isometric contractions in an aging workforce. PMID:25633070

  9. Small wind turbine for variable speed with flexible blades and automatically mechanical pitching

    DEFF Research Database (Denmark)

    Rasmussen, Tonny Wederberg; Johansen, Arne

    2017-01-01

    Wind energy have for many years been a growing alternative to fossil energy. The sizes of turbines are increasing to megawatt level. Wind turbines operate in a wide range of wind speeds but are shot down for high wind speeds. Traditional concepts are relatively stiff and have a cause stress...... on the gearbox. The turbine described in this paper overcomes some of these challenges by having flexibly and pitchebly blades. This means that the turbine can operate at turbulent sites and withstand wind burst without high stress level on the gearbox. This paper describes the mechanical principle, electrical...

  10. Potentials of wind power

    International Nuclear Information System (INIS)

    Bezrukikh, P.P.; Bezrukikh, P.P.

    2000-01-01

    The ecological advantages of the wind power facilities (WPF) are considered. The possibilities of small WPF, generating the capacity from 40 W up to 10 kW, are discussed. The basic technical data on the national and foreign small WPF are presented. The combined wind power systems are considered. Special attention is paid to the most perspective wind-diesel systems, which provide for all possible versions of the electro-power supply. Useful recommendations and information on the wind power engineering are given for those, who decided to build up a wind facility [ru

  11. Visualization of wind farms

    International Nuclear Information System (INIS)

    Pahlke, T.

    1994-01-01

    With the increasing number of wind energy installations the visual impact of single wind turbines or wind parks is a growing problem for landscape preservation, leading to resistance of local authorities and nearby residents against wind energy projects. To increase acceptance and to form a basis for planning considerations, it is necessary to develop instruments for the visualization of planned wind parks, showing their integration in the landscape. Photorealistic montages and computer animation including video sequences may be helpful in 'getting the picture'. (orig.)

  12. Mapping Wind Energy Controversies

    DEFF Research Database (Denmark)

    Munk, Anders Kristian

    As part the Wind2050 project funded by the Danish Council for Strategic Research we have mapped controversies on wind energy as they unfold online. Specifically we have collected two purpose built datasets, a web corpus containing information from 758 wind energy websites in 6 different countries......, and a smaller social media corpus containing information from 14 Danish wind energy pages on Facebook. These datasets have been analyzed to answer questions like: How do wind proponents and opponents organize online? Who are the central actors? And what are their matters of concern? The purpose of this report...

  13. Wind energy applications guide

    Energy Technology Data Exchange (ETDEWEB)

    anon.

    2001-01-01

    The brochure is an introduction to various wind power applications for locations with underdeveloped transmission systems, from remote water pumping to village electrification. It includes an introductory section on wind energy, including wind power basics and system components and then provides examples of applications, including water pumping, stand-alone systems for home and business, systems for community centers, schools, and health clinics, and examples in the industrial area. There is also a page of contacts, plus two specific example applications for a wind-diesel system for a remote station in Antarctica and one on wind-diesel village electrification in Russia.

  14. Wind energy systems

    International Nuclear Information System (INIS)

    Richardson, R.D.; McNerney, G.M.

    1993-01-01

    Wind energy has matured to a level of development where it is ready to become a generally accepted utility generation technology. A brief discussion of this development is presented, and the operating and design principles are discussed. Alternative designs for wind turbines and the tradeoffs that must be considered are briefly compared. Development of a wind energy system and the impacts on the utility network including frequency stability, voltage stability, and power quality are discussed. The assessment of wind power station economics and the key economic factors that determine the economic viability of a wind power plant are presented

  15. Fault Tolerant Wind Farm Control

    DEFF Research Database (Denmark)

    Odgaard, Peter Fogh; Stoustrup, Jakob

    2013-01-01

    In the recent years the wind turbine industry has focused on optimizing the cost of energy. One of the important factors in this is to increase reliability of the wind turbines. Advanced fault detection, isolation and accommodation are important tools in this process. Clearly most faults are dealt...... with best at a wind turbine control level. However, some faults are better dealt with at the wind farm control level, if the wind turbine is located in a wind farm. In this paper a benchmark model for fault detection and isolation, and fault tolerant control of wind turbines implemented at the wind farm...... control level is presented. The benchmark model includes a small wind farm of nine wind turbines, based on simple models of the wind turbines as well as the wind and interactions between wind turbines in the wind farm. The model includes wind and power references scenarios as well as three relevant fault...

  16. Wind Tunnel Measurements at LM Wind Power

    DEFF Research Database (Denmark)

    Bertagnolio, Franck

    2012-01-01

    This section presents the results obtained during the experimental campaign that was conducted in the wind tunnel at LM Wind Power in Lunderskov from August 16th to 26th, 2010. The goal of this study is to validate the so-called TNO trailing edge noise model through measurements of the boundary...... layer turbulence characteristics and the far-field noise generated by the acoustic scattering of the turbulent boundary layer vorticies as they convect past the trailing edge. This campaign was conducted with a NACA0015 airfoil section that was placed in the wind tunnel section. It is equipped with high...

  17. Wind energy in Europe

    International Nuclear Information System (INIS)

    Evans, L.C.

    1992-01-01

    Wind energy should be an important part of the energy supply mix, both at home and abroad, to provide cleaner air and a more stable fuel supply. Not only can wind energy contribute to solving complex global issues, it also can provide a large market for American technological leadership. Even though utilities are paying more attention to wind in a number of states, there are no plans for major installations of wind power plants in the United States. At the same time, European nations have developed aggressive wind energy development programs, including both ambitious research and development efforts and market incentives. Many countries recognize the importance of the clean energy provided by wind technology and are taking steps to promote their fledgling domestic industries. The emphasis on market incentives is starting to pay off. In 1991, European utilities and developers installed nearly twice as much wind capacity as Americans did. In 1992 the gap will be even greater. This article reviews aggressive incentives offered by European governments to boost their domestic wind industries at home and abroad in this almost $1 billion per year market. By offering substantial incentives - considerably more than the American Wind Energy Association (AWEA) is proposing - European nations are ensuring dramatic near-term wind energy development and are taking a major step toward dominating the international wind industry of the 21st century

  18. Kansas Wind Energy Consortium

    Energy Technology Data Exchange (ETDEWEB)

    Gruenbacher, Don [Kansas State Univ., Manhattan, KS (United States)

    2015-12-31

    This project addresses both fundamental and applied research problems that will help with problems defined by the DOE “20% Wind by 2030 Report”. In particular, this work focuses on increasing the capacity of small or community wind generation capabilities that would be operated in a distributed generation approach. A consortium (KWEC – Kansas Wind Energy Consortium) of researchers from Kansas State University and Wichita State University aims to dramatically increase the penetration of wind energy via distributed wind power generation. We believe distributed generation through wind power will play a critical role in the ability to reach and extend the renewable energy production targets set by the Department of Energy. KWEC aims to find technical and economic solutions to enable widespread implementation of distributed renewable energy resources that would apply to wind.

  19. Wind Turbine Technologies

    DEFF Research Database (Denmark)

    Hansen, Anca Daniela

    2017-01-01

    The wind turbine technology is a very complex technology involving multidisciplinary and broad technical disciplines such as aerodynamics, mechanics, structure dynamics, meteorology as well as electrical engineering addressing the generation, transmission, and integration of wind turbines...... into the power system. Wind turbine technology has matured over the years and become the most promising and reliable renewable energy technology today. It has moved very fast, since the early 1980s, from wind turbines of a few kilowatts to today’s multimegawatt-sized wind turbines [13]. Besides their size......, the design of wind turbines has changed from being convention driven to being optimized driven within the operating regime and market environment. Wind turbine designs have progressed from fixed speed, passive controlled and with drive trains with gearboxes, to become variable speed, active controlled...

  20. 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.

  1. Turning to the wind

    Science.gov (United States)

    Sorensen, B.

    1981-10-01

    Consideration is given the economic and technological aspects of both free-stream (horizontal-axis) and cross-wind (vertical-axis) wind energy conversion systems, with attention to operational devices ranging in rotor diameter from 10 to 40 m and in output from 22 to 630 kW. After a historical survey of wind turbine design and applications development, the near-term technical feasibility and economic attractiveness of combined wind/fossil-fueled generator and wind/hydroelectric systems are assessed. Also presented are estimates of wind energy potential extraction in the U.S. and Denmark, the industrial requirements of large-scale implementation, energy storage possibilities such as pumped hydro and flywheels, and cost comparisons of electrical generation by large and small wind systems, coal-fired plants, and light-water fission reactors.

  2. Wind power takes over

    International Nuclear Information System (INIS)

    2002-01-01

    All over the industrialized world concentrated efforts are being made to make wind turbines cover some of the energy demand in the coming years. There is still a long way to go, however, towards a 'green revolution' as far as energy is concerned, for it is quite futile to use wind power for electric heating. The article deals with some of the advantages and disadvantages of developing wind power. In Norway, for instance, environmentalists fear that wind power plants along the coast may have serious consequences for the stocks of white-tailed eagle and golden eagle. An other factor that delays the large-scale application of wind power in Norway is the low price of electricity. Some experts, however, maintain that wind power may already compete with new hydroelectric power of intermediate cost. The investment costs are expected to go down with one third by 2020, when wind power may be the most competitive energy source to utilize

  3. Wind energy conversion system

    Science.gov (United States)

    Longrigg, Paul

    1987-01-01

    The wind energy conversion system includes a wind machine having a propeller connected to a generator of electric power, the propeller rotating the generator in response to force of an incident wind. The generator converts the power of the wind to electric power for use by an electric load. Circuitry for varying the duty factor of the generator output power is connected between the generator and the load to thereby alter a loading of the generator and the propeller by the electric load. Wind speed is sensed electro-optically to provide data of wind speed upwind of the propeller, to thereby permit tip speed ratio circuitry to operate the power control circuitry and thereby optimize the tip speed ratio by varying the loading of the propeller. Accordingly, the efficiency of the wind energy conversion system is maximized.

  4. Interaction of turbulent length scales with wind turbine blades

    Science.gov (United States)

    Torres-Nieves, Sheilla N.

    wind turbine blade as a consequence of its geometry) on the behavior of turbulent boundary layers and to identify and quantify the length scales that are affected by these external conditions. Laser Doppler and hot-wire anemometry measurements, for smooth and rough surfaces, confirmed that FST and FPG cause a reduction in the wake of the boundary layer. Moreover, results show a discrepancy in the behavior of the stream-wise and wall-normal variances due to free-stream turbulence. As a result, the addition of FST increases the anisotropy in the body of the boundary layer. For FPG flows, a budget analysis of the Reynolds stresses shows that turbulent transport and pressure strain terms are responsible for the increase in the stream-wise Reynolds stress component when FST is present. Second-order structure functions and energy spectra are examined to identify and quantify which turbulence length-scales contribute mostly to the increased anisotropy, and to compare these effects to the case of a zero pressure gradient (ZPG) boundary layer. For ZPG flows, it is shown that the anisotropy created by adding nearly isotropic turbulence in the free-stream resides mostly in the larger scales of the flow, in a range between r/delta95 = 3 and 10. With an imposed FPG, the effect of FST resides in the very-largest length scales of the flow, r ≥ 4.3delta95, corresponding to scales of the same size, and even larger, than the integral scale of the outer free-stream turbulence. However, the free-stream turbulence is not increasing the anisotropy to the extent that it did for the ZPG case. The effects of surface roughness on the different length scales of the flow, when a FPG and additional levels of FST are present, are also examined. Second-order structure functions and energy spectra analysis suggests that for highly turbulent favorable pressure gradient flows, the effect of roughness at the surface is felt, not only by the small length scales of the flow, but also by large (e.g. r

  5. Advantages on monitoring wind turbine nacelle oscillation

    DEFF Research Database (Denmark)

    Skrimpas, Georgios Alexandros; Marhadi, Kun Saptohartyadi; Hilmisson, Reynir

    2015-01-01

    Nacelle oscillation monitoring, where accelerometers are mounted on the nacelle frame, is integral part of modern condition monitoring systems towards holistic and consistent health assessment of wind turbines. It enables detection of abnormal behavior associated to increased stresses and vibrati......Nacelle oscillation monitoring, where accelerometers are mounted on the nacelle frame, is integral part of modern condition monitoring systems towards holistic and consistent health assessment of wind turbines. It enables detection of abnormal behavior associated to increased stresses...... and vibrations on blades, tower and drive train components, which may jeopardize their working condition. The present paper deals with the comparison and analysis of vibration signals from wind turbines subjected to various failure modes and operating conditions, such as blade misalignment, pitch malfunction......, ice accretion, damaged blade tips and yaw system defects. Theoretical analysis of nacelle movement at down wind and lateral direction is presented along with field results from multi megawatt wind turbines. Additionally the paper discusses the employment of nacelle accelerometers for cross reference...

  6. Second wind in the offshore wind industry

    International Nuclear Information System (INIS)

    Philippe, Edouard; Neyme, Eric; Deboos, Christophe; Villageois, Jean-Remy; Gouverneur, Philippe; Gerard, Bernard; Fournier, Eric; Petrus, Raymond; Lemarquis, David; Dener, Marc; Bivaud, Jean-Pierre; Lemaire, Etienne; Nielsen, Steffen; Lafon, Xavier; Lagandre, Pierre; Nadai, Alain; Pinot de Villechenon, Edouard; Westhues, Markus; Herpers, Frederick; Bisiaux, Christophe; Sperlich, Miriam; Bales, Vincent; Vandenbroeck, Jan; His, Stephane; Derrey, Thierry; Barakat, Georges; Dakyo, Brayima; Carme, Laurent; Petit, Frederic; Ytournel, Sophie; Westhues, Markus; Diller, Armin; Premont, Antoine de; Ruer, Jacques; Lanoe, Frederic; Declercq, Jan; Holmager, Morten; Fidelin, Daniel; Guillet, Jerome; Dudziak, Gregory; Lapierre, Anne; Couturier, Ludovic; Audineau, Jean-Pierre; Rouaix, Eric; De Roeck, Yann-Herve; Quesnel, Louis; Duguet, Benjamin

    2011-06-01

    After several keynote addresses, this publication contains contributions and Power Point presentations proposed during this conference on the development of offshore wind energy. The successive sessions addressed the following issues: the offshore mass production of electricity (examples of Denmark and Belgium, laying and protecting offshore cables), the space, economic and environmental planning (the Danish experience, the role of the Coastal area integrated management, importance of the public debate, so on), the logistics of port infrastructures (simulation tools, example of Bremerhaven, issues related to project management), innovation at the core of industrial strategies (high power wind turbines, the 6 MW Alstom turbine, chain value and innovation in offshore wind energy, the Vertiwing innovating project of a floating wind turbine, a bench test in Charleston, foundations, gravity base structures, the British experience, the Danish experience), the economic and organisational conditions for development, the validation and certification of technologies

  7. A short G1 phase imposes constitutive replication stress and fork remodelling in mouse embryonic stem cells

    DEFF Research Database (Denmark)

    Ahuja, Akshay K.; Jodkowska, Karolina; Teloni, Federico

    2016-01-01

    Embryonic stem cells (ESCs) represent a transient biological state, where pluripotency is coupled with fast proliferation. ESCs display a constitutively active DNA damage response (DDR), but its molecular determinants have remained elusive. Here we show in cultured ESCs and mouse embryos that H2AX...... slowing and reversal leads to chromosomal breakage in unperturbed ESCs. We propose that rapid cell cycle progression makes ESCs dependent on effective replication-coupled mechanisms to protect genome integrity....

  8. Wind Turbine Contingency Control Through Generator De-Rating

    Science.gov (United States)

    Frost, Susan; Goebel, Kai; Balas, Mark

    2013-01-01

    Maximizing turbine up-time and reducing maintenance costs are key technology drivers for wind turbine operators. Components within wind turbines are subject to considerable stresses due to unpredictable environmental conditions resulting from rapidly changing local dynamics. In that context, systems health management has the aim to assess the state-of-health of components within a wind turbine, to estimate remaining life, and to aid in autonomous decision-making to minimize damage to the turbine. Advanced contingency control is one way to enable autonomous decision-making by providing the mechanism to enable safe and efficient turbine operation. The work reported herein explores the integration of condition monitoring of wind turbines with contingency control to balance the trade-offs between maintaining system health and energy capture. The contingency control involves de-rating the generator operating point to achieve reduced loads on the wind turbine. Results are demonstrated using a high fidelity simulator of a utility-scale wind turbine.

  9. Power Electronics for the Next Generation Wind Turbine System

    DEFF Research Database (Denmark)

    Ma, Ke

    The wind power generation has been steadily growing both for the total installed capacity and for the individual turbine size. Due to much more significant impacts to the power grid, the power electronics, which can change the behavior of wind turbines from an unregulated power source to an active...... generation unit, are becoming crucial in the wind turbine system. The objective of this project is to study the power electronics technology used for the next generation wind turbines. Some emerging challenges as well as potentials like the cost of energy and reliability are going to be addressed. First...... several potential converter topologies and power semiconductor devices for the future wind power application are presented in respect to the advantages/drawbacks. And then the criteria for evaluating the wind power converter are generally discussed, where the importance of thermal stress in the power...

  10. Student-Life Stress Inventory.

    Science.gov (United States)

    Gadzella, Bernadette M.; And Others

    The reliability of the Student-Life Stress Inventory of B. M. Gadzella (1991) was studied. The inventory consists of 51 items listed in 9 sections indicating different types of stressors (frustrations, conflicts, pressures, changes, and self-imposed stressors) and reactions to the stressors (physiological, emotional, behavioral, and cognitive) as…

  11. 36 CFR 1280.34 - What are the types of corrective action NARA imposes for prohibited behavior?

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false What are the types of corrective action NARA imposes for prohibited behavior? 1280.34 Section 1280.34 Parks, Forests, and Public... corrective action NARA imposes for prohibited behavior? (a) Individuals who violate the provisions of this...

  12. 26 CFR 301.7422-1 - Special rules for certain excise taxes imposed by chapter 42 or 43.

    Science.gov (United States)

    2010-04-01

    ... 26 Internal Revenue 18 2010-04-01 2010-04-01 false Special rules for certain excise taxes imposed... Proceedings Civil Actions by the United States § 301.7422-1 Special rules for certain excise taxes imposed by... modified or reversed as the result of a decision of a higher court, upon the expiration, with respect to...

  13. 28 CFR 522.13 - Relationship between existing civil contempt commitment orders and new criminal sentences imposed...

    Science.gov (United States)

    2010-07-01

    ... contempt commitment orders and new criminal sentences imposed under the U.S. or D.C. Code. 522.13 Section..., CLASSIFICATION, AND TRANSFER ADMISSION TO INSTITUTION Civil Contempt of Court Commitments § 522.13 Relationship between existing civil contempt commitment orders and new criminal sentences imposed under the U.S. or D.C...

  14. Observability of wind power

    International Nuclear Information System (INIS)

    Gonot, J.P.; Fraisse, J.L.

    2009-01-01

    The total installed capacity of wind power grows from a few hundred MW at the beginning of 2005 to 3400 MW at the end of 2008. With such a trend, a total capacity of 7000 MW could be reached by 2010. The natural variability of wind power and the difficulty of its predictability require a change in the traditional way of managing supply/demand balance, day-ahead margins and the control of electrical flows. As a consequence, RTE operators should be informed quickly and reliably of the real time output power of wind farms and of its evolvement some hours or days ahead to ensure the reliability of the French electrical power system. French specificities are that wind farms are largely spread over the territory, that 95 % of wind farms have an output power below 10 MW and that they are connected to the distribution network. In this context, new tools were necessary to acquire as soon as possible data concerning wind power. In two years long, RTE set up an observatory of wind production 'IPES system' enable to get an access to the technical characteristics of the whole wind farms, to observe in real time 75 % of the wind generation and to implement a forecast model related to wind generation. (authors)

  15. Financing wind projects

    International Nuclear Information System (INIS)

    Manson, J.

    2006-01-01

    This presentation reviewed some of the partnership opportunities available from GE Energy. GE Energy's ecomagination commitment has promised to double research investment, make customers true partners and reduce greenhouse gases (GHGs). GE Energy's renewable energy team provides a broad range of financial products, and has recently funded 30 wind farms and 2 large solar projects. The company has a diverse portfolio of technology providers and wind regimes, and is increasing their investment in technology. GE Energy recognizes that the wind industry is growing rapidly and has received increased regulatory support that is backed by strong policy and public support. It is expected that Canada will have 3006 wind projects either planned or under construction by 2007. According to GE Energy, successful wind financing is dependent on the location of the site and its wind resources, as well as on the wind developer's power sales agreement. The success of a wind project is also determined by clear financing goals. Site-specific data is needed to determine the quality of wind resource, and off-site data can also be used to provide validation. Proximity to load centres will help to minimize capital costs. Power sales agreements should be based on the project's realistic net capacity factor as well as on the cost of the turbines. The economics of many wind farms is driven by the size of the turbines used. Public consultations are also needed to ensure the success of wind power projects. It was concluded that a good partner will have staying power in the wind power industry, and will understand the time-lines and needs that are peculiar to wind energy developers. refs., tabs., figs

  16. Filament winding cylinders. I - Process model

    Science.gov (United States)

    Lee, Soo-Yong; Springer, George S.

    1990-01-01

    A model was developed which describes the filament winding process of composite cylinders. The model relates the significant process variables such as winding speed, fiber tension, and applied temperature to the thermal, chemical and mechanical behavior of the composite cylinder and the mandrel. Based on the model, a user friendly code was written which can be used to calculate (1) the temperature in the cylinder and the mandrel, (2) the degree of cure and viscosity in the cylinder, (3) the fiber tensions and fiber positions, (4) the stresses and strains in the cylinder and in the mandrel, and (5) the void diameters in the cylinder.

  17. Market microstructure matters when imposing a Tobin tax—Evidence from the lab☆

    Science.gov (United States)

    Kirchler, Michael; Huber, Jürgen; Kleinlercher, Daniel

    2011-01-01

    Trading in FX markets is dominated by two microstructures: exchanges with market makers and OTC-markets without market makers. Using laboratory experiments we test whether the impact of a Tobin tax is different in these two market microstructures. We find that (i) in markets without market makers an unilaterally imposed Tobin tax (i.e. a tax haven exists) increases volatility. (ii) In contrast, in markets with market makers we observe a decrease in volatility in unilaterally taxed markets. (iii) An encompassing Tobin tax has no impact on volatility in either setting. Efficiency does not vary significantly across tax regimes. PMID:22210970

  18. Market microstructure matters when imposing a Tobin tax-Evidence from the lab.

    Science.gov (United States)

    Kirchler, Michael; Huber, Jürgen; Kleinlercher, Daniel

    2011-12-01

    TRADING IN FX MARKETS IS DOMINATED BY TWO MICROSTRUCTURES: exchanges with market makers and OTC-markets without market makers. Using laboratory experiments we test whether the impact of a Tobin tax is different in these two market microstructures. We find that (i) in markets without market makers an unilaterally imposed Tobin tax (i.e. a tax haven exists) increases volatility. (ii) In contrast, in markets with market makers we observe a decrease in volatility in unilaterally taxed markets. (iii) An encompassing Tobin tax has no impact on volatility in either setting. Efficiency does not vary significantly across tax regimes.

  19. Offshore Wind Power Data

    DEFF Research Database (Denmark)

    Cutululis, Nicolaos Antonio; Litong-Palima, Marisciel; Zeni, Lorenzo

    2012-01-01

    Wind power development scenarios are critical when trying to assess the impact of the demonstration at national and European level. The work described in this report had several objectives. The main objective was to prepare and deliver the proper input necessary for assessing the impact of Demo 4...... – Storm management at national and European level. For that, detailed scenarios for offshore wind power development by 2020 and 2030 were required. The aggregation level that is suitable for the analysis to be done is at wind farm level. Therefore, the scenarios for offshore wind power development offer...... details about the wind farms such as: capacity and coordinates. Since the focus is on the impact of storm fronts passage in Northen Europe, the offshore wind power scenarios were estimated only for the countries at North and Baltic Sea. The sources used are public sources, mentioned in the reference list...

  20. Wind farm economics

    International Nuclear Information System (INIS)

    Milborrow, D.J.

    1995-01-01

    The economics of wind energy are changing rapidly, with improvements in machine performance and increases in size both contributing to reduce costs. These trends are examined and future costs assessed. Although the United Kingdom has regions of high wind speed, these are often in difficult terrain and construction costs are often higher than elsewhere in Europe. Nevertheless, wind energy costs are converging with those of the conventional thermal sources. At present, bank loan periods for wind projects are shorter than for thermal plant, which means that energy prices are higher. Ways of overcoming this problem are explored. It is important, also, to examine the value of wind energy. It is argued that wind energy has a higher value than energy from centralized plant, since it is fed into the low-voltage distribution network. (Author)

  1. Wind power in France

    International Nuclear Information System (INIS)

    Tuille, F.; Courtel, J.

    2015-01-01

    After 3 years of steady decreasing, wind power has resumed growth in 2014 in France and the preliminary figures of 2015 confirm this trend. About 1100 MW were installed in 2014 which was almost twice as much as it was installed the year before. This renaissance is mostly due to the implementation of Brottes' law that eases the installations of wind farms by suppressing the wind power development areas (that were interfering with regional wind power schemes) and by suppressing the minimum number of 5 turbines for any new wind farms. Another important incentive measure was the announcement in January 2015 of a new financial support scheme in replacement of the policy of guaranteed purchase price for the electricity produced. In 2014 the total wind power produced in mainland France reached 17 TW which represented 3.1% of the production of electricity. (A.C.)

  2. 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...

  3. Wind turbine state estimation

    DEFF Research Database (Denmark)

    Knudsen, Torben

    2014-01-01

    the results using full-scale wind turbine data. The previously developed methods were based on extended Kalman filtering. This method has several drawback compared to unscented Kalman filtering which has therefore been developed. The unscented Kalman filter was first tested on linear and non-linear test cases......Dynamic inflow is an effect which is normally not included in the models used for wind turbine control design. Therefore, potential improvement from including this effect exists. The objective in this project is to improve the methods previously developed for this and especially to verify...... which was successful. Then the estimation of a wind turbine state including dynamic inflow was tested on a simulated NREL 5MW turbine was performed. This worked perfectly with wind speeds from low to nominal wind speed as the output prediction errors where white. In high wind where the pitch actuator...

  4. 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)

  5. Wind turbine pitch optimization

    DEFF Research Database (Denmark)

    Biegel, Benjamin; Juelsgaard, Morten; Stoustrup, Jakob

    2011-01-01

    We consider a static wind model for a three-bladed, horizontal-axis, pitch-controlled wind turbine. When placed in a wind field, the turbine experiences several mechanical loads, which generate power but also create structural fatigue. We address the problem of finding blade pitch profiles......% compared to any constant pitch profile while sacrificing at most 7% of the maximum attainable output power. Using iterative learning, we show that very similar performance can be achieved by using only load measurements, with no knowledge of the wind field or wind turbine model....... for maximizing power production while simultaneously minimizing fatigue loads. In this paper, we show how this problem can be approximately solved using convex optimization. When there is full knowledge of the wind field, numerical simulations show that force and torque RMS variation can be reduced by over 96...

  6. SERI Wind Energy Program

    Energy Technology Data Exchange (ETDEWEB)

    Noun, R. J.

    1983-06-01

    The SERI Wind Energy Program manages the areas or innovative research, wind systems analysis, and environmental compatibility for the U.S. Department of Energy. Since 1978, SERI wind program staff have conducted in-house aerodynamic and engineering analyses of novel concepts for wind energy conversion and have managed over 20 subcontracts to determine technical feasibility; the most promising of these concepts is the passive blade cyclic pitch control project. In the area of systems analysis, the SERI program has analyzed the impact of intermittent generation on the reliability of electric utility systems using standard utility planning models. SERI has also conducted methodology assessments. Environmental issues related to television interference and acoustic noise from large wind turbines have been addressed. SERI has identified the causes, effects, and potential control of acoustic noise emissions from large wind turbines.

  7. 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...

  8. Danish Wind Power

    DEFF Research Database (Denmark)

    Lund, Henrik; Hvelplund, Frede; Østergaard, Poul Alberg

    In a normal wind year, Danish wind turbines generate the equivalent of approx. 20 percent of the Danish electricity demand. This paper argues that only approx. 1 percent of the wind power production is exported. The rest is used to meet domestic Danish electricity demands. The cost of wind power......, a study made by the Danish think tank CEPOS claimed the opposite, i.e. that most of the Danish wind power has been exported in recent years. However, this claim is based on an incorrect interpretation of statistics and a lack of understanding of how the international electricity markets operate...... is paid solely by the electricity consumers and the net influence on consumer prices was as low as 1-3 percent on average in the period 2004-2008. In 2008, the net influence even decreased the average consumer price, although only slightly. In Denmark, 20 percent wind power is integrated by using both...

  9. 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....

  10. 77 FR 29633 - Alta Wind VII, LLC, Alta Wind IX, LLC, Alta Wind X, LLC, Alta Wind XI, LLC, Alta Wind XII, LLC...

    Science.gov (United States)

    2012-05-18

    ..., Alta Wind XIV, LLC, Alta Wind XV, LLC, Alta Windpower Development, LLC, TGP Development Company, LLC... XIII, LLC, Alta Wind XIV, LLC, Alta Wind XV, LLC, Alta Windpower Development, LLC, and TGP Development...

  11. 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.

  12. Enabling Wind Power Nationwide

    Energy Technology Data Exchange (ETDEWEB)

    Jose Zayas, Michael Derby, Patrick Gilman and Shreyas Ananthan,

    2015-05-01

    Leveraging this experience, the U.S. Department of Energy’s (DOE’s) Wind and Water Power Technologies Office has evaluated the potential for wind power to generate electricity in all 50 states. This report analyzes and quantifies the geographic expansion that could be enabled by accessing higher above ground heights for wind turbines and considers the means by which this new potential could be responsibly developed.

  13. Wind and Yaw correlation

    DEFF Research Database (Denmark)

    Kock, Carsten Weber; Vesth, Allan

    The report describes measurements carried out on a given wind turbine. A comparison between wind speed on the metmast and Nacelle Windspeed are made and the results are presented on graphs and in a table. The data used for the comparison are identical with the data used for the Risø-I-3246(EN......) power curve report. The measurements are carried out in accordance to Ref. [1] and the wind and yaw correlation is analyzed in accordance to Ref. [2]....

  14. Hurricane Resilient Wind Plant Concept Study Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Dibra, Besart [Keystone Engineering Inc., Vonore, TN (United States); Finucane, Zachary [Keystone Engineering Inc., Vonore, TN (United States); Foley, Benjamin [Keystone Engineering Inc., Vonore, TN (United States); Hall, Rudy [Keystone Engineering Inc., Vonore, TN (United States); Damiani, Rick [National Renewable Energy Lab. (NREL), Golden, CO (United States); Maples, Benjamin [National Renewable Energy Lab. (NREL), Golden, CO (United States); Parker, Zachary [National Renewable Energy Lab. (NREL), Golden, CO (United States); Robertson, Amy [National Renewable Energy Lab. (NREL), Golden, CO (United States); Scott, George [National Renewable Energy Lab. (NREL), Golden, CO (United States); Stehly, Tyler [National Renewable Energy Lab. (NREL), Golden, CO (United States); Wendt, Fabian [National Renewable Energy Lab. (NREL), Golden, CO (United States); Andersen, Mads Boel Overgaard [Siemens Wind Power A/S, Brande (Denmark); Standish, Kevin [Siemens Wind Power A/S, Brande (Denmark); Lee, Ken [Wetzel Engineering Inc., Round Rock, TX (United States); Raina, Amool [Wetzel Engineering Inc., Round Rock, TX (United States); Wetzel, Kyle [Wetzel Engineering Inc., Round Rock, TX (United States); Musial, Walter [National Renewable Energy Lab. (NREL), Golden, CO (United States); Schreck, Scott [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2016-10-01

    Hurricanes occur over much of the U.S. Atlantic and Gulf coasts, from Long Island to the U.S.-Mexico border, encompassing much of the nation's primary offshore wind resource. Category 5 hurricanes have made landfall as far north as North Carolina, with Category 3 hurricanes reaching New York with some frequency. Along the US West coast, typhoons strike with similar frequency and severity. At present, offshore wind turbine design practices do not fully consider the severe operating conditions imposed by hurricanes. Although universally applied to most turbine designs, International Electrotechnical Commission (IEC) standards do not sufficiently address the duration, directionality, magnitude, or character of hurricanes. To assess advanced design features that could mitigate hurricane loading in various ways, this Hurricane-Resilient Wind Plant Concept Study considered a concept design study of a 500-megawatt (MW) wind power plant consisting of 10-MW wind turbines deployed in 25-meter (m) water depths in the Western Gulf of Mexico. This location was selected because hurricane frequency and severity provided a unique set of design challenges that would enable assessment of hurricane risk and projection of cost of energy (COE) changes, all in response to specific U.S. Department of Energy (DOE) objectives. Notably, the concept study pursued a holistic approach that incorporated multiple advanced system elements at the wind turbine and wind power plant levels to meet objectives for system performance and reduced COE. Principal turbine system elements included a 10-MW rotor with structurally efficient, low-solidity blades; a lightweight, permanent-magnet, direct-drive generator, and an innovative fixed substructure. At the wind power plant level, turbines were arrayed in a large-scale wind power plant in a manner aimed at balancing energy production against capital, installation, and operation and maintenance (O&M) costs to achieve significant overall reductions in

  15. Presentation of a stochastic model estimating the wind energy contribution in remote island electrical networks

    International Nuclear Information System (INIS)

    Kaldellis, J.K.; Kapsali, M.; Tiligadas, D.

    2012-01-01

    Highlights: ► This study estimates the maximum wind energy contribution to an isolated micro-grid. ► An integrated computational tool is developed on the basis of stochastic analysis. ► The probability distribution of the wind energy surplus and deficit is estimated. ► The results indicate that a strict penetration limit is imposed to wind energy. -- Abstract: The electrification in remote islands whose electricity distribution network is not connected to the mainland’s grid is mostly based on Autonomous Power Stations (APSs) that are usually characterized by a considerably high electricity production cost, while at the same time the contribution of Renewable Energy Sources (RES) in these regions accounts for less than 10% of the total electricity generation. This actually results from the fact that despite the excellent wind potential of most of these islands, the wind energy contribution is significantly restricted from limits imposed to protect the remote electrical grids from possible instability problems, due to the stochastic wind speed behavior and the variable electricity consumption. On the basis of probability distribution of the load demand of a representative Greek island and the corresponding data related to the available wind potential, the present study estimates the maximum – acceptable by the local grid – wind energy contribution. For that reason, an integrated computational algorithm has been developed from first principles, based on a stochastic analysis. According to the results obtained, it becomes evident that with the current wind turbine technology, wind energy cannot play a key role in coping with the electrification problems encountered in many Greek island regions, excluding however the case of introducing bulk energy storage systems that may provide considerable recovery of the remarkable wind energy rejections expected.

  16. Wind power prediction models

    Science.gov (United States)

    Levy, R.; Mcginness, H.

    1976-01-01

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

  17. Wind on the moors

    International Nuclear Information System (INIS)

    Martin, S.

    1992-01-01

    A local town councillor describes the setting up of a wind farm in the south Pennines which plans to sell electricity to the local electricity suppliers. The Coal Clough wind farm will generate sufficient electricity to meet the average demand of 7,500 households and will be managed by a consortium known as Wind Resources Limited linking the construction company and the utilities aiming to buy the electricity produced. While wind power offers many environmental advantages over other means of power generation, local opposition was strong on the basis of the noise produced and clearly visible structures in an area designated as being of outstanding natural beauty. (UK)

  18. 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

  19. Microsystem Aeromechanics Wind Tunnel

    Data.gov (United States)

    Federal Laboratory Consortium — The Microsystem Aeromechanics Wind Tunnel advances the study of fundamental flow physics relevant to micro air vehicle (MAV) flight and assesses vehicle performance...

  20. Winds of change

    International Nuclear Information System (INIS)

    Palmer, C.; Short, L.

    1998-01-01

    The British countryside is oversubscribed with multiple and often irreconcilable demands. The siting of wind turbines is but one facet of this situation. While the problems of these demands are widely recognised, there is little understanding or agreement on how to resolve them. The 1996 Future Landscape: New Partnerships was an attempt to address this challenge. The use of wind energy as a case study initiated a partnership between contemporary artists and the wind energy industry. It became clear that artists have an important role to play in creating new ways of seeing that will establish wind turbines as new icons for a sustainable future. (Author)

  1. Could wind replace nuclear?

    International Nuclear Information System (INIS)

    2017-01-01

    This article aims at assessing the situation produced by a total replacement of nuclear energy by wind energy, while facing consumption demand at any moment, notably in December. The authors indicate the evolution of the French energy mix during December 2016, and the evolution of the rate between wind energy production and the sum of nuclear and wind energy production during the same month, and then give briefly some elements regarding necessary investments in wind energy to wholly replace nuclear energy. According to them, such a replacement would be ruinous

  2. Climate Wind Power Resources

    Directory of Open Access Journals (Sweden)

    Nana M. Berdzenishvili

    2013-01-01

    Full Text Available Georgia as a whole is characterized by rather rich solar energy resources, which allows to construct alternative power stations in the close proximity to traditional power plants. In this case the use of solar energy is meant. Georgia is divided into 5 zones based on the assessment of wind power resources. The selection of these zones is based on the index of average annual wind speed in the examined area, V> 3 m / s and V> 5 m / s wind speed by the summing duration in the course of the year and V = 0. . . 2 m / s of passive wind by total and continuous duration of these indices per hour.

  3. Wind Energy Facilities

    Energy Technology Data Exchange (ETDEWEB)

    Laurie, Carol

    2017-02-01

    This book takes readers inside the places where daily discoveries shape the next generation of wind power systems. Energy Department laboratory facilities span the United States and offer wind research capabilities to meet industry needs. The facilities described in this book make it possible for industry players to increase reliability, improve efficiency, and reduce the cost of wind energy -- one discovery at a time. Whether you require blade testing or resource characterization, grid integration or high-performance computing, Department of Energy laboratory facilities offer a variety of capabilities to meet your wind research needs.

  4. Vertical axis wind turbines

    Science.gov (United States)

    Krivcov, Vladimir [Miass, RU; Krivospitski, Vladimir [Miass, RU; Maksimov, Vasili [Miass, RU; Halstead, Richard [Rohnert Park, CA; Grahov, Jurij [Miass, RU

    2011-03-08

    A vertical axis wind turbine is described. The wind turbine can include a top ring, a middle ring and a lower ring, wherein a plurality of vertical airfoils are disposed between the rings. For example, three vertical airfoils can be attached between the upper ring and the middle ring. In addition, three more vertical airfoils can be attached between the lower ring and the middle ring. When wind contacts the vertically arranged airfoils the rings begin to spin. By connecting the rings to a center pole which spins an alternator, electricity can be generated from wind.

  5. 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

  6. Wind Turbines Make Waves: Why Some Residents near Wind Turbines Become Ill

    Science.gov (United States)

    Havas, Magda; Colling, David

    2011-01-01

    People who live near wind turbines complain of symptoms that include some combination of the following: difficulty sleeping, fatigue, depression, irritability, aggressiveness, cognitive dysfunction, chest pain/pressure, headaches, joint pain, skin irritations, nausea, dizziness, tinnitus, and stress. These symptoms have been attributed to the…

  7. Transition to magnetorotational turbulence in Taylor–Couette flow with imposed azimuthal magnetic field

    International Nuclear Information System (INIS)

    A Guseva; Avila, M; Willis, A P; Hollerbach, R

    2015-01-01

    The magnetorotational instability (MRI) is thought to be a powerful source of turbulence and momentum transport in astrophysical accretion discs, but obtaining observational evidence of its operation is challenging. Recently, laboratory experiments of Taylor–Couette flow with externally imposed axial and azimuthal magnetic fields have revealed the kinematic and dynamic properties of the MRI close to the instability onset. While good agreement was found with linear stability analyses, little is known about the transition to turbulence and transport properties of the MRI. We here report on a numerical investigation of the MRI with an imposed azimuthal magnetic field. We show that the laminar Taylor–Couette flow becomes unstable to a wave rotating in the azimuthal direction and standing in the axial direction via a supercritical Hopf bifurcation. Subsequently, the flow features a catastrophic transition to spatio-temporal defects which is mediated by a subcritical subharmonic Hopf bifurcation. Our results are in qualitative agreement with the PROMISE experiment and dramatically extend their realizable parameter range. We find that as the Reynolds number increases defects accumulate and grow into turbulence, yet the momentum transport scales weakly. (paper)

  8. Egg eviction imposes a recoverable cost of virulence in chicks of a brood parasite.

    Directory of Open Access Journals (Sweden)

    Michael G Anderson

    2009-11-01

    Full Text Available Chicks of virulent brood parasitic birds eliminate their nestmates and avoid costly competition for foster parental care. Yet, efforts to evict nest contents by the blind and naked common cuckoo Cuculus canorus hatchling are counterintuitive as both adult parasites and large older cuckoo chicks appear to be better suited to tossing the eggs and young of the foster parents.Here we show experimentally that egg tossing imposed a recoverable growth cost of mass gain in common cuckoo chicks during the nestling period in nests of great reed warbler Acrocephalus arundinaceus hosts. Growth rates of skeletal traits and morphological variables involved in the solicitation of foster parental care remained similar between evictor and non-evictor chicks throughout development. We also detected no increase in predation rates for evicting nests, suggesting that egg tossing behavior by common cuckoo hatchlings does not increase the conspicuousness of nests.The temporary growth cost of egg eviction by common cuckoo hatchlings is the result of constraints imposed by rejecter host adults and competitive nestmates on the timing and mechanism of parasite virulence.

  9. Imposed, ordered dust structures and other plasma features in a strongly magnetized plasma

    Science.gov (United States)

    Thomas, Edward; Leblanc, Spencer; Lynch, Brian; Konopka, Uwe; Merlino, Robert; Rosenberg, Marlene

    2015-11-01

    The Magnetized Dusty Plasma Experiment (MDPX) device has been in operation for just over one year. In that time, the MDPX device has been operating using a uniform magnetic field configuration up to 3.0 Tesla and has successfully produced plasmas and dusty plasmas at high magnetic fields. In these experimental studies, we have made observations of a new type of imposed, ordered structure in a dusty plasma at magnetic fields above 1 T. These dusty plasma structures are shown to scale inversely with neutral pressure and are shown to reflect the spatial structure of a wire mesh placed in the plasma. Additionally, recent measurements have been made that give insights into the effective potential that establishes the ordered structures in the plasma. In this presentation, we report on details of the imposed, ordered dusty plasma structure as well as filamentary features that also appear in the plasma and modify the confinement of the dusty plasma. This work is supported with funding from the NSF and Department of Energy.

  10. Imposing a pause between the eccentric and concentric phases increases the reliability of isoinertial strength assessments.

    Science.gov (United States)

    Pallarés, Jesús G; Sánchez-Medina, Luis; Pérez, Carlos Esteban; De La Cruz-Sánchez, Ernesto; Mora-Rodriguez, Ricardo

    2014-01-01

    This study analysed the effect of imposing a pause between the eccentric and concentric phases on the biological within-subject variation of velocity- and power-load isoinertial assessments. Seventeen resistance-trained athletes undertook a progressive loading test in the bench press (BP) and squat (SQ) exercises. Two trials at each load up to the one-repetition maximum (1RM) were performed using 2 techniques executed in random order: with (stop) and without (standard) a 2-s pause between the eccentric and concentric phases of each repetition. The stop technique resulted in a significantly lower coefficient of variation for the whole load-velocity relationship compared to the standard one, in both BP (2.9% vs. 4.1%; P = 0.02) and SQ (2.9% vs. 3.9%; P = 0.01). Test-retest intraclass correlation coefficients (ICCs) were r = 0.61-0.98 for the standard and r = 0.76-0.98 for the stop technique. Bland-Altman analysis showed that the error associated with the standard technique was 37.9% (BP) and 57.5% higher (SQ) than that associated with the stop technique. The biological within-subject variation is significantly reduced when a pause is imposed between the eccentric and concentric phases. Other relevant variables associated to the load-velocity and load-power relationships such as the contribution of the propulsive phase and the load that maximises power output remained basically unchanged.

  11. Wind Power Today: (2002) Wind Energy Research Highlights

    Energy Technology Data Exchange (ETDEWEB)

    2003-05-01

    Wind Power Today is an annual publication that provides an overview of the wind research conducted under the U.S. Department of Energy's Wind and Hydropower Technologies Program. The purpose of Wind Power Today is to show how DOE supports wind turbine research and deployment in hopes of furthering the advancement of wind technologies that produce clean, low-cost, reliable energy. Content objectives include: educate readers about the advantages and potential for widespread deployment of wind energy; explain the program's objectives and goals; describe the program's accomplishments in research and application; examine the barriers to widespread deployment; describe the benefits of continued research and development; facilitate technology transfer; and attract cooperative wind energy projects with industry. This 2002 edition of Wind Power Today also includes discussions about wind industry growth in 2002, how DOE is taking advantage of low wind speed regions through advancing technology, and distributed applications for small wind turbines.

  12. Sensing the wind profile

    Energy Technology Data Exchange (ETDEWEB)

    Pena, A.

    2009-03-15

    This thesis consists of two parts. The first is a synopsis of the theoretical progress of the study that is based on a number of journal papers. The papers, which constitute the second part of the report, aim to analyze, measure, and model the wind prole in and beyond the surface layer by combining observations from cup anemometers with lidars. The lidar is necessary to extend the measurements on masts at the Horns Rev offshore wind farm and over at land at Hoevsoere, Denmark. Both sensing techniques show a high degree of agreement for wind speed measurements performed at either sites. The wind speed measurements are averaged for several stability conditions and compare well with the surface-layer wind profile. At Hoevsoere, it is sufficient to scale the wind speed with the surface friction velocity, whereas at Horns Rev a new scaling is added, due to the variant roughness length. This new scaling is coupled to wind prole models derived for flow over the sea and tested against the wind proles up to 160 m at Horns Rev. The models, which account for the boundary-layer height in stable conditions, show better agreement with the measurements than compared to the traditional theory. Mixing-length parameterizations for the neutral wind prole compare well with length-scale measurements up to 300 m at Hoevsoere and 950 m at Leipzig. The mixing-length-derived wind proles strongly deviate from the logarithmic wind prole, but agree better with the wind speed measurements. The length-scale measurements are compared to the length scale derived from a spectral analysis performed up to 160 m at Hoevsoere showing high agreement. Mixing-length parameterizations are corrected to account for stability and used to derive wind prole models. These compared better to wind speed measurements up to 300 m at Hoevsoere than the surface-layer wind prole. The boundary-layer height is derived in nearneutral and stable conditions based on turbulent momentum uxes only and in unstable conditions

  13. Wind energy - an overview

    International Nuclear Information System (INIS)

    Rangi, R.; Oprisan, M.

    1998-01-01

    The current status of wind technology developments in Canada and around the world was reviewed. Information regarding the level of wind turbine deployment was presented. It was shown that significant effort has been made on the national and international level to increase the capacity of this clean, non-polluting form of energy. Wind energy has become competitive with conventional sources of electricity due to lower cost, higher efficiency and improved reliability of generating equipment. The advantages and disadvantages of wind electricity generating systems and the economics and atmospheric emissions of the systems were described. At present, there is about 23 MW of wind energy generating capacity installed in Canada, but the potential is very large. It was suggested that wind energy could supply as much as 60 per cent of Canada's electricity needs if only one per cent of the land with 'good winds' were covered by wind turbines. Recently, the Canadian government has provided an accelerated capital cost allowance for certain types of renewable energies under the Income Tax Act, and the flow-through share financing legislation to include intangible expenses in certain renewable energy projects has been extended. Besides the support provided to the private sector through tax advantages, the Government also supports renewable energy development by purchasing 'green' energy for its own buildings across the country, and by funding a research and development program to identify and promote application of wind energy technologies, improve its cost effectiveness, and support Canadian wind energy industries with technology development to enhance their competitiveness at home and abroad. Details of the Wind Energy Program, operated by Natural Resources Canada, are described. 3 tabs., 5 figs

  14. LCT-coil design: Mechanical interaction between composite winding and steel casing under various test conditions

    International Nuclear Information System (INIS)

    Dolensky, B.; Messemer, G.; Zehlein, H.; Erb, J.

    1981-01-01

    Finite element computations for the structural design of the large superconducting toroidal field coil contributed by EURATOM to the Large Coil Test Facility (LCTF) at ORNL, USA were performed at KfK, using the ASKA code. The layout of the coil must consider different types of requirements: firstly, an optimal D-shaped contour minimizing circumferential stress gradients under normal operation in the toroidal arrangement must be defined. Secondly, the three-dimensional real design effects due to the actual support conditions, manufacturing tolerances etc. must be mastered for different basic operational and failure load cases. And, thirdly, the design must stand a single coil qualification test in the TOSKA-facility at KfK, Karlsruhe, FRG, before it is plugged into the LCTF. The emphasis of the paper is three-pronged according to these requirements: i) the 3D magnetic body forces as well as the underlying magnetic fields as computed by the HEDO-code are described. ii) The mechanical interaction between casing and winding as given elsewhere in terms of high stress regions, gaps, slide movements and contact forces for various load cases representing the LCTF test conditions is illustrated here by a juxtaposition of the operational deformations and stresses within the LCTF and the TOSKA. iii) Particular effects like the restraint imposed by a corset-type reinforcement of the coil in the TOSKA test facility to limit the breathing deformation are parametrically studied. Moreover, the possibilities to derive scaling laws which make essential results transferable to larger coils by extracting a 1D mechanical response from the 3D finite element model is also demonstrated. (orig./GG)

  15. 40 CFR 90.427 - Catalyst thermal stress resistance evaluation.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Catalyst thermal stress resistance... Gaseous Exhaust Test Procedures § 90.427 Catalyst thermal stress resistance evaluation. (a) The purpose of... catalyst conversion efficiency for Phase 1 engines. The thermal stress is imposed on the test catalyst by...

  16. Wind power integration : From individual wind turbine to wind park as a power plant

    NARCIS (Netherlands)

    Zhou, Y.

    2009-01-01

    As power capacities of single wind turbine, single wind park and total wind power installation are continuously increasing, the wind power begins to challenge the safety operation of the power system. This thesis focuses on the grid integration aspects such as the dynamic behaviours of wind power

  17. Mesoscale Influences of Wind Farms Throughout a Diurnal Cycle

    Science.gov (United States)

    Fitch, A. C.; Lundquist, J. K.; Olson, J. B.

    2012-12-01

    Few observations are available to give insight into the interaction between large wind farms and the boundary layer. As wind farm deployment increases, questions are arising on the potential impact on meteorology within and downwind of large wind farms. While large-eddy simulation can provide insight into the detailed interaction between individual turbines and the boundary layer, to date it has been too computationally expensive to simulate wind farms with large numbers of turbines and the resulting wake far downstream. Mesoscale numerical weather prediction models provide the opportunity to investigate the flow in and around large wind farms as a whole, and the resulting impact on meteorology. To this end, we have implemented a wind farm parameterization in the Weather Research and Forecasting (WRF) model, which represents wind turbines by imposing a momentum sink on the mean flow; converting kinetic energy into electricity and turbulent kinetic energy (TKE). The parameterization improves upon previous models, basing the atmospheric drag of turbines on the thrust coefficient of a modern commercial turbine. In addition, the source of TKE varies with wind speed, reflecting the amount of energy extracted from the atmosphere by the turbines that does not produce electrical energy. We simulate a wind farm covering 10x10 km over land, consisting of 100 turbines each of nominal power output of 5 MW. Results will be presented showing how the wake structure varies dramatically over a diurnal cycle characteristic of a region in the Great Plains of the US, where wind farm deployment is planned. At night, a low-level jet forms within the rotor area, which is completely eliminated by energy extraction within the wind farm. The deep stable layer and lack of higher momentum air aloft at this time maximises the wind deficit and the length of the wake. The presentation will discuss the maximum reduction of wind speed within and downwind from the farm, and the wake e

  18. Wind speed dynamical model in a wind farm

    DEFF Research Database (Denmark)

    Soleimanzadeh, Maryam; Wisniewski, Rafal

    2010-01-01

    , the dynamic model for wind flow will be established. The state space variables are determined based on a fine mesh defined for the farm. The end goal of this method is to assist the development of a dynamical model of a wind farm that can be engaged for better wind farm control strategies.......This paper presents a model for wind speed in a wind farm. The basic purpose of the paper is to calculate approximately the wind speed in the vicinity of each wind turbine in a farm. In this regard the governing equations of flow will be solved for the whole wind farm. In ideal circumstances...

  19. Modeling and control of PMSG-based variable-speed wind turbine

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hong-Woo; Ko, Hee-Sang [Wind Energy Research Center, Korea Institute of Energy Research, Yuseong-gu Jang-Dong 71-2,305-343 Daejeon (Korea); Kim, Sung-Soo [Chungbuk National University (Korea)

    2010-01-15

    This paper presents a control scheme of a variable-speed wind turbine with a permanent-magnetic synchronous generator (PMSG) and full-scale back-to-back voltage source converter. A comprehensive dynamical model of the PMSG wind turbine and its control scheme is presented. The control scheme comprises both the wind-turbine control itself and the power-converter control. In addition, since the PMSG wind turbine is able to support actively the grid due to its capability to control independently active and reactive power production to the imposed set-values with taking into account its operating state and limits, this paper presents the supervisory reactive power control scheme in order to regulate/contribute the voltage at a remote location. The ability of the control scheme is assessed and discussed by means of simulations, based on a candidate site of the offshore wind farm in Jeju, Korea. (author)

  20. Implementation of a Wind Farm Turbine Control System with Short-Term Grid Faults Management

    DEFF Research Database (Denmark)

    Marra, Francesco; Rasmussen, Tonny Wederberg; Garcia-Valle, Rodrigo

    2010-01-01

    restrictions for the wind turbines behavior especially under grid faults. Wind turbines are requested to stay connected even during faults. These new requirements are challenging the control of the wind turbines and new control strategies are required to meet the target. This paper dealt...... with the implementation of a control strategy in order to stay connected under grid faults. The method aimed to ensure that a wind farm turbine remains connected and no electric power is delivered to the grid during the fault period. The overall system was modelled and simulated by using the software Matlab/Simulink.......The increased penetration of wind power in the grid has led to important technical barriers that limit the development, where the stability of the system plays a key issue. Grid operators in different countries are issuing new grid requirements, the so-called grid codes that impose more...

  1. Fixture for winding transformers

    Science.gov (United States)

    Mclyman, M. T.

    1980-01-01

    Bench-mounted fixture assists operator in winding toroid-shaped transformer cores. Toroid is rigidly held in place as wires are looped around. Arrangement frees both hands for rapid winding and untangling of wires that occurs when core is hand held.

  2. Wind turbines and infrasound

    International Nuclear Information System (INIS)

    Howe, B.

    2006-01-01

    This paper provided the results of a study conducted to assess the impacts of wind farm-induced infrasound on nearby residences and human populations. Infrasound occurs at frequencies below those considered as detectable by human hearing. Infrasonic levels caused by wind turbines are often similar to ambient levels of 85 dBG or lower that are caused by wind in the natural environment. This study examined the levels at which infrasound poses a threat to human health or can be considered as an annoyance. The study examined levels of infrasound caused by various types of wind turbines, and evaluated acoustic phenomena and characteristics associated with wind turbines. Results of the study suggested that infrasound near modern wind turbines is typically not perceptible to humans through either auditory or non-auditory mechanisms. However, wind turbines often create an audible broadband noise whose amplitude can be modulated at low frequencies. A review of both Canadian and international studies concluded that infrasound generated by wind turbines should not significantly impact nearby residences or human populations. 17 refs., 2 tabs., 4 figs

  3. NORCOWE Reference Wind Farm

    DEFF Research Database (Denmark)

    Bak, Thomas; Graham, Angus

    2015-01-01

    Offshore wind farms are complex systems, influenced by both the environment (e.g. wind, waves, current and seabed) and the design characteristics of the equipment available for installation (e.g. turbine type, foundations, cabling and distance to shore). These aspects govern the capital and opera...

  4. MWR, Meteor Wind Radars

    Science.gov (United States)

    Roper, R. G.

    1984-01-01

    The requirements of a state of the art meteor wind radar, and acceptable comprises in the interests of economy, are detailed. Design consideration of some existing and proposed radars are discussed. The need for international cooperation in mesopause level wind measurement, such as that being fostered by the MAP GLOBMET (Global Meteor Observations System) project, is emphasized.

  5. Research on wind energy

    CSIR Research Space (South Africa)

    Szewczuk, S

    2012-10-01

    Full Text Available & underlying technologies Ovid: composite man- rated trainer airplane Eskom?s wind farm, Klipheuwel, Cape Town ? CSIR, then DME & City of Cape Town undertook study on large grid connected wind turbines ? included a study tour to Europe. ? Recommended...

  6. Emerging wind energy technologies

    DEFF Research Database (Denmark)

    Rasmussen, Flemming; Grivel, Jean-Claude; Faber, Michael Havbro

    2014-01-01

    This chapter will discuss emerging technologies that are expected to continue the development of the wind sector to embrace new markets and to become even more competitive.......This chapter will discuss emerging technologies that are expected to continue the development of the wind sector to embrace new markets and to become even more competitive....

  7. Aerodynamics of wind turbines

    DEFF Research Database (Denmark)

    Hansen, Martin Otto Laver

    Aerodynamics of Wind Turbines is the established essential text for the fundamental solutions to efficient wind turbine design. Now in its third edition, it has been substantially updated with respect to structural dynamics and control. The new control chapter now includes details on how to design...

  8. Aerodynamics of Wind Turbines

    DEFF Research Database (Denmark)

    Hansen, Martin Otto Laver

    Aerodynamics of Wind Turbines is the established essential text for the fundamental solutions to efficient wind turbine design. Now in its second edition, it has been entirely updated and substantially extended to reflect advances in technology, research into rotor aerodynamics and the structural...

  9. The difficult wind power

    International Nuclear Information System (INIS)

    Groenaas, Sigbjoern

    2005-01-01

    The article presents a brief survey of the conditions for wind power production in Norway and points out that several areas should be well suited. A comparison to Danish climate is made. The wind variations, turbulence problems and regional conditions are discussed

  10. Wind Energy Systems.

    Science.gov (United States)

    Conservation and Renewable Energy Inquiry and Referral Service (DOE), Silver Spring, MD.

    During the 1920s and 1930s, millions of wind energy systems were used on farms and other locations far from utility lines. However, with passage of the Rural Electrification Act in 1939, cheap electricity was brought to rural areas. After that, the use of wind machines dramatically declined. Recently, the rapid rise in fuel prices has led to a…

  11. Fort Carson Wind Resource Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Robichaud, R.

    2012-10-01

    This report focuses on the wind resource assessment, the estimated energy production of wind turbines, and economic potential of a wind turbine project on a ridge in the southeastern portion of the Fort Carson Army base.

  12. Offshore Wind Power

    DEFF Research Database (Denmark)

    Negra, Nicola Barberis

    The aim of the project is to investigate the influence of wind farms on the reliability of power systems. This task is particularly important for large offshore wind farms, because failure of a large wind farm might have significant influence on the balance of the power system, and because offshore...... Carlo simulation is used for these calculations: this method, in spite of an extended computation time, has shown flexibility in performing reliability studies, especially in case of wind generation, and a broad range of results which can be evaluated. The modelling is then extended to the entire power...... system considering conventional power plants, distributed generation based on wind energy and CHP technology as well as the load and transmission facilities. In particular, the different models are used to represent two well-known test systems, the RBTS and the IEEE-RTS, and to calculate...

  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. Aeroservoelasticity of Wind Turbines

    DEFF Research Database (Denmark)

    Kallesøe, Bjarne Skovmose

    2007-01-01

    This thesis deals with the fundamental aeroelastic interaction between structural motion, Pitch action and control for a wind turbine blade. As wind turbines become larger, the interaction between pitch action, blade motion, aerodynamic forces, and control become even more important to understand...... to a 2D blade section model, and it can be used instead of this in many applications, giving a transparent connection to a real wind turbine blade. In this work the aeroelastic blade model is used to analyze interaction between pitch action, blade motion and wind speed variations. Furthermore the model...... conditions. So, a new aeroelastic blade model has been derived, which includes important features of large wind turbines, yet simple enough to be suitable for analytical analysis and control design....

  16. Aerodynamics of Wind Turbines

    DEFF Research Database (Denmark)

    Hansen, Martin Otto Laver

    Aerodynamics of Wind Turbines is the established essential text for the fundamental solutions to efficient wind turbine design. Now in its second edition, it has been entirely updated and substantially extended to reflect advances in technology, research into rotor aerodynamics and the structural...... response of the wind turbine structure. Topics covered include increasing mass flow through the turbine, performance at low and high wind speeds, assessment of the extreme conditions under which the turbine will perform and the theory for calculating the lifetime of the turbine. The classical Blade Element...... Momentum method is also covered, as are eigenmodes and the dynamic behavior of a turbine. The new material includes a description of the effects of the dynamics and how this can be modeled in an aeroelastic code, which is widely used in the design and verification of modern wind turbines. Further...

  17. Optimization of wind turbine rotors

    Energy Technology Data Exchange (ETDEWEB)

    Nygaard, Tor Anders

    1999-07-01

    The Constrained Steepest Descent method has been applied to the optimization of wind turbine rotors through the development of a numerical model. The model consists of an optimization kernel, an aerodynamic model, a structural dynamic model of a rotating beam, and a cost model for the wind turbine. The cost of energy is minimized directly by varying the blade design, the rotational speed and the resulting design of the drive-train and tower. The aerodynamic model is a combination of a fast engineering model based on strip-theory and two and three-dimensional Euler solvers. The two-dimensional Euler solver is used for generation of pre-stall airfoil data. Comparisons with experimental data verify that the engineering model effectively approximates non-stalled flow, except at the blade tip. The three-dimensional Euler solver is in good agreement with the experimental data at the tip, and is therefore a useful supplement for corrections of the tip-loss model, and evaluation of an optimized design. The structural dynamic model evaluates stresses and deformations for the blade. It is based on constitutive relations for a slender beam that are solved with the equations of motions using a finite-difference method. The cost model evaluates the design change of the wind turbine and the resulting costs that occur when a change in blade design modifies the blade mass and the overall forces. The cost model is based on engineering design rules for the drive-train and tower. The model was applied using a Danish 600 kW wind turbine as a reference. Two rotors were optimized using traditional NACA airfoils and a new low-lift airfoil family developed specifically for wind turbine purposes. The cost of energy decreased four percent for the NACA rotor, and seven percent for the low-lift rotor. Optimizations with a high number of degrees of freedom show that a designer has considerable flexibility in choosing some primary parameters such as rated power and rotor diameter, if the rest

  18. European Wind Atlas and Wind Resource Research in Denmark

    DEFF Research Database (Denmark)

    Mortensen, Niels Gylling

    to estimate the actual wind climate at any specific site and height within this region. The Danish and European Wind Atlases are examples of how the wind atlas methodology can be employed to estimate the wind resource potential for a country or a sub-continent. Recently, the methodology has also been used...... - from wind measurements at prospective sites to wind tunnel simulations and advanced flow modelling. Among these approaches, the wind atlas methodology - developed at Ris0 National Laboratory over the last 25 years - has gained widespread recognition and is presently considered by many as the industry......-standard tool for wind resource assessment and siting of wind turbines. The PC-implementation of the methodology, the Wind Atlas Analysis and Application Program (WAsP), has been applied in more than 70 countries and territories world-wide. The wind atlas methodology is based on physical descriptions and models...

  19. Itinerarios imposibles del sujeto nómade en la hora de la estrella

    Directory of Open Access Journals (Sweden)

    Angélica Tatiana Vargas Ortiz

    2011-12-01

    Full Text Available http://dx.doi.org/10.5007/2176-8522.2009n9p39 En La Hora de la Estrella de Clarice Lispector el sujeto emprende la búsqueda de su identidad a través de desplazamientos propios de su naturaleza nómade. Estos desplazamientos de la consciencia del sujeto forman una serie de itinerarios que revelan algunas imposibilidades que el sujeto nómade sufre en una sociedad que lo condena a su alienación. La imposibilidad de la autoconsciencia del yo, su devenir animal y el vaciamiento del deseo, son parte de estos itinerarios imposibles que acontecen en la novela.

  20. Imposed Stories: Prisoner Self-narratives in the Criminal Justice System in New South Wales, Australia

    Directory of Open Access Journals (Sweden)

    Maggie Hall

    2016-03-01

    Full Text Available This article examines the ways in which offenders are required to provide very particular accounts of themselves and to self-narrate in confined ways. Drawing on ethnographic fieldwork and interviews conducted in the New South Wales justice system, it explores how the stories that offenders are made to accept and tell about themselves often bear little relationship to their own reflections. It analyses how, despite the expectations of judges and prison authorities, these self-narratives are not products of an offender’s soul-searching concerning his past actions and experience; rather they are products of an official legal narrative being imposed on an offender whose capacity to own and enact such a narrative is already seriously compromised.

  1. Stimulated Raman Scattering Imposes Fundamental Limits to the Duration and Bandwidth of Temporal Cavity Solitons

    Science.gov (United States)

    Wang, Yadong; Anderson, Miles; Coen, Stéphane; Murdoch, Stuart G.; Erkintalo, Miro

    2018-02-01

    Temporal cavity solitons (CS) are optical pulses that can persist in passive resonators, and they play a key role in the generation of coherent microresonator frequency combs. In resonators made of amorphous materials, such as fused silica, they can exhibit a spectral redshift due to stimulated Raman scattering. Here we show that this Raman-induced self-frequency-shift imposes a fundamental limit on the duration and bandwidth of temporal CSs. Specifically, we theoretically predict that stimulated Raman scattering introduces a previously unidentified Hopf bifurcation that leads to destabilization of CSs at large pump-cavity detunings, limiting the range of detunings over which they can exist. We have confirmed our theoretical predictions by performing extensive experiments in synchronously driven fiber ring resonators, obtaining results in excellent agreement with numerical simulations. Our results could have significant implications for the future design of Kerr frequency comb systems based on amorphous microresonators.

  2. Tribal communities and coal in Northeast India: The politics of imposing and resisting mining bans

    International Nuclear Information System (INIS)

    McDuie-Ra, Duncan; Kikon, Dolly

    2016-01-01

    Bans on coal mining have been implemented in two tribal majority states in India's north-east frontier; Nagaland and Meghalaya. In Nagaland the state government imposed the ban in an attempt to capture control of coal extraction and trade, while in Meghalaya India's National Green Commission imposed the ban over concern for the environment and labour conditions. In both cases local communities have opposed the bans, and in some areas resumed mining under the authority of tribal councils and powerful civil society actors. In this paper we explore the politics of coal extraction that resulted in these bans and the response of communities and authorities. In doing so we made three main arguments that contribute to understanding of coal and communities in frontier regions where state control is partial and the legacy of armed conflict is powerful. First, in both locations the majority of the coal mining activity has been initiated and managed by members of tribal communities rather than profit-driven outsiders. Second, in contrast to other contexts in India (notably Orissa and Jharkhand) where large state or private enterprises seek to modify the law to enable coal extraction, in Nagaland and Meghalaya it has been communities that resent and challenge state and national laws being applied to their lands. Third, the right to extract coal is connected to the right of tribal communities to determine what happens on their lands. - Highlights: • Tribal communities initiate and manage coal mining in Nagaland and Meghalaya. • Laws banning coal extraction have been challenged and resisted by local communities. • The right to extract coal is tied to protecting tribal land rights. • Tribal autonomy in coal policy is progressive, yet enables capture by local elites. • Where there has been regulation of coal mining it has come from unexpected sources.

  3. Effects of imposed resistance on tidal volume with 5 neonatal nasal continuous positive airway pressure systems.

    Science.gov (United States)

    Cook, Shannon E; Fedor, Katherine L; Chatburn, Robert L

    2010-05-01

    Neonates with respiratory distress syndrome are often treated with nasal continuous positive airway pressure (CPAP). Nasal CPAP methods include electronic feedback control, underwater seal, flow opposition, and flow opposition with fluidic flow reversal on expiration. Few studies have compared those modes, and the results have been contradictory. We compared the effect of resistive load on simulated tidal volume (V(T)) with 5 neonatal nasal CPAP systems: Fisher and Paykel nasal CPAP tubing with Maquet Servo-i ventilator in NIV CPAP mode; Cardinal Health AirLife nasal CPAP system; Fisher and Paykel nasal CPAP tubing with water-seal pressure generator; AirLife infant nasal CPAP generator kit; and Hamilton Medical Arabella fluidic nasal CPAP generator. The lung simulator settings were: compliance 0.5 mL/cm H2O, resistance 125 H2O/L/s, sinusoidal patient-effort range 6.5-26 cm H2O, rise 25%, hold 0%, release 25%, respiratory rate 65 breaths/min. We compared the mean values from 10 breaths. The mean inspiratory pressure drop and V(T) difference (compared to the simulator alone, unloaded) increased with V(T), respectively, from 0.32 cm H2O to 1.73 cm H2O, and from -0.04 mL to -0.40 mL. Flow opposition had the smallest pressure drop (from 0.10 cm H2O to 0.64 cm H2O, P nasal CPAP's pressure drop was largest (P or = 9 mL the electronic nasal CPAP's pressure drop was largest (P nasal CPAP systems correlate with the differences in unassisted V(T) due to loading effects. The ventilator imposed the least load, and the AirLife nasal CPAP system imposed the most.

  4. Protein Homeostasis Imposes a Barrier on Functional Integration of Horizontally Transferred Genes in Bacteria.

    Directory of Open Access Journals (Sweden)

    Shimon Bershtein

    2015-10-01

    Full Text Available Horizontal gene transfer (HGT plays a central role in bacterial evolution, yet the molecular and cellular constraints on functional integration of the foreign genes are poorly understood. Here we performed inter-species replacement of the chromosomal folA gene, encoding an essential metabolic enzyme dihydrofolate reductase (DHFR, with orthologs from 35 other mesophilic bacteria. The orthologous inter-species replacements caused a marked drop (in the range 10-90% in bacterial growth rate despite the fact that most orthologous DHFRs are as stable as E.coli DHFR at 37°C and are more catalytically active than E. coli DHFR. Although phylogenetic distance between E. coli and orthologous DHFRs as well as their individual molecular properties correlate poorly with growth rates, the product of the intracellular DHFR abundance and catalytic activity (kcat/KM, correlates strongly with growth rates, indicating that the drop in DHFR abundance constitutes the major fitness barrier to HGT. Serial propagation of the orthologous strains for ~600 generations dramatically improved growth rates by largely alleviating the fitness barriers. Whole genome sequencing and global proteome quantification revealed that the evolved strains with the largest fitness improvements have accumulated mutations that inactivated the ATP-dependent Lon protease, causing an increase in the intracellular DHFR abundance. In one case DHFR abundance increased further due to mutations accumulated in folA promoter, but only after the lon inactivating mutations were fixed in the population. Thus, by apparently distinguishing between self and non-self proteins, protein homeostasis imposes an immediate and global barrier to the functional integration of foreign genes by decreasing the intracellular abundance of their products. Once this barrier is alleviated, more fine-tuned evolution occurs to adjust the function/expression of the transferred proteins to the constraints imposed by the

  5. Industrial wind turbines and adverse health effects.

    Science.gov (United States)

    Jeffery, Roy D; Krogh, Carmen M E; Horner, Brett

    2014-01-01

    Some people living in the environs of industrial wind turbines (IWTs) report experiencing adverse health and socioeconomic effects. This review considers the hypothesis that annoyance from audible IWTs is the cause of these adverse health effects. We searched PubMed and Google Scholar for articles published since 2000 that included the terms "wind turbine health," "wind turbine infrasound," "wind turbine annoyance," "noise annoyance" or "low frequency noise" in the title or abstract. Industrial wind turbines produce sound that is perceived to be more annoying than other sources of sound. Reported effects from exposure to IWTs are consistent with well-known stress effects from persistent unwanted sound. If placed too close to residents, IWTs can negatively affect the physical, mental and social well-being of people. There is sufficient evidence to support the conclusion that noise from audible IWTs is a potential cause of health effects. Inaudible low-frequency noise and infrasound from IWTs cannot be ruled out as plausible causes of health effects.

  6. Co-generation of hydrogen from nuclear and wind: the effect on costs of realistic variations in wind generation. Paper no. IGEC-1-094

    International Nuclear Information System (INIS)

    Miller, A.I.; Duffey, R.B.

    2005-01-01

    Can electricity from high-capacity nuclear reactors be blended with the variable output of wind turbines to produce electrolytic hydrogen competitively? To be competitive with alternative sources, hydrogen produced by conventional electrolysis requires low-cost electricity (likely <2.5 cents US/kW.h). One approach is to operate interruptibly, allowing an installation to sell electricity when the grid price is high and to make hydrogen when it is low. Our previous studies show that this could be cost-competitive using nuclear power generator producing electricity around 3 cents US/kW.h. Although similar unit costs are projected for wind-generated electricity, idleness of the electrolysis facility due to the variability of wind-generated electricity imposes a significant cost penalty. This paper reports on ongoing work on the economics of blending electricity from nuclear and wind sources by using wind-generated power, when available, to augment the current through electrolysis equipment that is primarily nuclear-powered - a concept we call NuWind. A voltage penalty accompanies the higher current. A 10% increase in capital cost for electrolysis equipment to enable it to accommodate the higher rate of hydrogen generation is still substantially cheaper than the capital cost of wind-dedicated electrolysis. Real-time data for electricity costs have been combined with real-time wind variability. The variability in wind fields between sites was accommodated by assigning average wind speeds that produced an average electricity generation from wind of between 32 and 42% of peak capacity, which is typical of the expectations for superior wind-generation sites. (author)

  7. Anisotropy of turbulence in wind turbine wakes

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-Elvira, Rafael [Comision Nacional de Energia (Spain); Crespo, Antonio; Migoya, Emilio; Manuel, Fernando [Departamento de Ingenieria Energetica y Fluidomecanica, Escuela Tecnica Superior de Ingenieros Industriales, Universidad Politecnica de Madrid, Jose Gutierrez Abascal, 2. 28006 Madrid (Spain); Hernandez, Julio [Departamento de Mecanica, ETSII, Universidad Nacional de Educacion a Distancia, Ciudad Universitaria, 28040 Madrid (Spain)

    2005-10-01

    This work is mainly dedicated to the study of non-isotropic characteristics of turbulence in wind turbine wakes, specifically the shear layer of the near wake. A calculation method based on an explicit algebraic model for the components of the turbulent stress tensor is proposed, and the results are found to be in acceptable agreement with experimental results. Analytical expressions for the estimation of an upper limit of the global turbulence kinetic energy, k, and the individual contributions of each diagonal term in the turbulent stress tensor are proposed. Their predictions are compared with experimental results.

  8. Early stages of wind wave and drift current generation under non-stationary wind conditions.

    Science.gov (United States)

    Robles-Diaz, Lucia; Ocampo-Torres, Francisco J.; Branger, Hubert

    2016-04-01

    waves by turbulent wind." Journal of Fluid Mechanics, 2: 417-445. • Smith, Stuart D. 1980. "Wind Stress and Heat Flux over the Ocean in Gale Force Winds." Journal of Physical Oceanography 10: 709-26. • Yelland, Margaret, and Peter K. Taylor. 1996. "Wind Stress Measurements from the Open Ocean." Journal of Physical Oceanography 26: 541-58.

  9. Integrating Structural Health Management with Contingency Control for Wind Turbines

    Directory of Open Access Journals (Sweden)

    Kai Goebel

    2013-01-01

    Full Text Available Maximizing turbine up-time and reducing maintenance costs are key technology drivers for wind turbine operators. Components within wind turbines are subject to considerable stresses due to unpredictable environmental conditions resulting from rapidly changing local dynamics. In that context, systems health management has the aim to assess the state-of-health of components within a wind turbine, to estimate remaining life, and to aid in autonomous decision-making to minimize damage to the turbine. Advanced contingency control is one way to enable autonomous decision-making by providing the mechanism to enable safe and efficient turbine operation. The work reported herein explores the integration of condition monitoring of wind turbine blades with contingency control to balance the trade-offs between maintaining system health and energy capture. Results are demonstrated using a high fidelity simulator of a utility-scale wind turbine.

  10. On the dependence of sea surface roughness on wind waves

    DEFF Research Database (Denmark)

    Johnson, H.K.; Højstrup, J.; Vested, H.J.

    1998-01-01

    The influence of wind waves on the momentum transfer (wind stress) between the atmosphere and sea surface was studied using new measured data from the RASEX experiment and other datasets compiled by Donelan et al. Results of the data analysis indicate that errors in wind friction velocity u...... that calculations of the wind friction velocities using the wave-spectra-dependent expression of Hansen and Larsen agrees quite well with measured values during RASEX. It also gives a trend in Charnock parameter consistent with that found by combining the field data. Last, calculations using a constant Charnock...... parameter (0.018) also give very good results for the wind friction velocities at the RASEX site....

  11. Wind and tornado guidelines

    International Nuclear Information System (INIS)

    McDonald, J.R.

    1989-01-01

    The objective of the Department of Energy Natural Phenomena Hazards Project is to provide guidance and criteria for design of new facilities and for evaluation of existing ones subjected to extreme winds, earthquakes, and floods. This paper describes the treatment of wind and tornado hazards. Four facility-use categories are defined which represent increasing levels of risk to personnel or the environment in the event of a high wind event. Facilities are assigned to a particular category, depending on their mission, value, or toxic material content. The assigned facility-use category determines the design and evaluation criteria. The criteria are based on probabilistic hazard assessment. Performance goals are also specified for each facility-use category. A uniform approach to design wind loads, based on the ANSI A58.1-1982 standard, allows treatment of high winds and hurricane and tornado winds in a similar manner. Based on the wind hazard models, some sites must account for the possibility of tornadoes while others do not. Atmospheric pressure changes and missiles must be taken into account when considering tornadoes. The design and evaluation guidelines are designed to establish consistent levels of risk for different natural phenomena hazards and for facilities at different geographical locations

  12. Wind energy in Europe

    International Nuclear Information System (INIS)

    Sesto, E.

    1992-02-01

    Interest in wind energy as a supplementary source for the production of electricity has recently gained renewed momentum due to widespread concern about environmental impacts from the large scale use of fossil fuels and nuclear energy. In addition, political unrest in the Middle East has drawn attention to the importance of national energy self-sufficiency. European government administrations, however, have not yet fully appreciated the real worth of the 'clean energy' afforded by wind energy. In this regard, the European Wind Energy Association (EWEA) is acting as a strong voice to inform the public and energy planners by stimulating international wind energy R ampersand D cooperation, and organizing conferences to explain the advantages of wind energy. In October 1991, EWEA published a strategy document giving a picture of the real possibilities offered by wind energy within the geographical, social, and European economic context. This paper provides an overview of the more significant features to emerge from this document which represents a useful guideline for wind power plant technical/economic feasibility studies in that it contains brief notes on resource availability, land requirements, visual and acoustic impacts, turbine sizing, performance, interconnection to utility grids, maintenance and operating costs, safety, as well as, on marketing aspects

  13. Wind farms and planning

    International Nuclear Information System (INIS)

    Arkesteijn, L.; Havinga, R.; Benner, J.H.B.

    1992-01-01

    The siting of wind farms is becoming an increasingly important issue in the Netherlands. This paper gives an overview of the current situation concerning the planning of wind farms. We will pay attention to: Wind energy in official Dutch planning policy. To select the optimal sites, the government has made an administrative agreement with the 7 windy provinces. Nevertheless, wind energy is still fighting for a rightful position in physical planning policy. Some examples will illustrate this. Studies on siting and siting problems in the Netherlands. In order to gain more insight into aspects of wind farming several studies have been executed. In this paper special attention will be paid to the results of a study on the potential impact of large windturbine clusters on an existing agricutural area. Experiences with siting of wind farms in the Netherlands. Based on experiences with the planning and realization of farms, this paper gives the main problems. In the final part of the paper we present some general conclusions. Generally speaking, the knowledge is available for selecting optimal sites in the Netherlands. The basic problems for wind farming nowadays seem to be the visual impact and actually obtaining the ground. Nevertheless, there do seem to be enough sites for realizing the goals in the Netherlands. (au)

  14. Database on wind characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, K.S. [The Technical Univ. of Denmark (Denmark); Courtney, M.S. [Risoe National Lab., (Denmark)

    1999-08-01

    The organisations that participated in the project consists of five research organisations: MIUU (Sweden), ECN (The Netherlands), CRES (Greece), DTU (Denmark), Risoe (Denmark) and one wind turbine manufacturer: Vestas Wind System A/S (Denmark). The overall goal was to build a database consisting of a large number of wind speed time series and create tools for efficiently searching through the data to select interesting data. The project resulted in a database located at DTU, Denmark with online access through the Internet. The database contains more than 50.000 hours of measured wind speed measurements. A wide range of wind climates and terrain types are represented with significant amounts of time series. Data have been chosen selectively with a deliberate over-representation of high wind and complex terrain cases. This makes the database ideal for wind turbine design needs but completely unsuitable for resource studies. Diversity has also been an important aim and this is realised with data from a large range of terrain types; everything from offshore to mountain, from Norway to Greece. (EHS)

  15. 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

  16. Type IV Wind Turbine Model

    DEFF Research Database (Denmark)

    Hansen, Anca Daniela; Margaris, Ioannis D.

    (WPP) will be considered. The aggregate WPP model, which will be based on the upscaling of the individual wind turbine model on the electrical part, will make use of an equivalent wind speed. The implemented model follows the basic structure of the generic standard Type 4 wind turbine model proposed...... by the International Electrotechnical Commission (IEC), in the IEC61400-27-1 Committee Draft for electrical simulation models for wind power generation, which is currently under review, [1]. The Type 4 wind turbine model described in this report includes a set of adjustments of the standard Type 4 wind turbine model...... project to be incorporated in the wind power plant level. This document describes the Type 4 wind turbine simulation model, implemented in the EaseWind project. The implemented wind turbine model is one of the initial necessary steps toward integrating new control services in the wind power plant level...

  17. Operations model for utilities using wind-generator arrays

    Science.gov (United States)

    Schlueter, R. A.; Park, G. L.; Dorsey, J.; Lotfalian, M.; Shayanfar, A.

    1981-05-01

    The effects that various combinations of wind regime, array configuration and penetrations, and system characteristics have on system variables such as area control error, frequency, interchange power and spinning reserve are discussed. The characteristics of the combinations causing system operating stress or operating problems are denoted and methods for estimating effects on a simplified and on a detailed simulation basis are reported. Methods for reducing operating problems are suggested and involve array configurations, penetration, unit commitment and dispatch changes, and wind generator controls.

  18. Filament winding cylinders. III - Selection of the process variables

    Science.gov (United States)

    Lee, Soo-Yong; Springer, George S.

    1990-01-01

    By using the Lee-Springer filament winding model temperatures, degrees of cure, viscosities, stresses, strains, fiber tensions, fiber motions, and void diameters were calculated in graphite-epoxy composite cylinders during the winding and subsequent curing. The results demonstrate the type of information which can be generated by the model. It is shown, in reference to these results, how the model, and the corresponding WINDTHICK code, can be used to select the appropriate process variables.

  19. Calculating wind profiles above a pine forest

    International Nuclear Information System (INIS)

    Murphy, C.E.; Dexter, A.H.

    1978-01-01

    A major part of the environmental transport work at the Savannah River Laboratory (SRL) involves the dispersion of airborne pollutants (aerosols and gases). A major part of the Savannah River Plant (SRP) site is covered with pine forests. Because forests are ''rough'' surfaces which increase turbulence and surface shear stress and, hence, alter the dispersion patterns, the nature of the wind profiles above the forests is being investigated. Two methods for determining the surface shear caused by the atmospheric wind field over a pine plantation were compared. Friction velocity [the square root of the ratio of shearing stress over the density of air; U/sub */ = (stress/density)1/2] calculated by eddy correlation was compared with friction velocity calculated from wind profiles. Data from the first five meters above the pine forest were compared. The data indicated that there was no significant difference in the mean friction velocity measured by each method. However, there were large differences in individual values calculated by the two methods for many of the measurement periods. An attempt was made to reconcile the differences in the measured values, but no satisfactory method was found

  20. Offshore wind turbine foundation monitoring, extrapolating fatigue measurements from fleet leaders to the entire wind farm

    Science.gov (United States)

    Weijtens, Wout; Noppe, Nymfa; Verbelen, Tim; Iliopoulos, Alexandros; Devriendt, Christof

    2016-09-01

    The present contribution is part of the ongoing development of a fatigue assessment strategy driven purely on in-situ measurements on operational wind turbines. The primary objective is to estimate the remaining life time of existing wind farms and individual turbines by instrumenting part of the farm with a load monitoring setup. This load monitoring setup allows to measure interface loads and local stress histories. This contribution will briefly discuss how these load measurements can be translated into fatigue assessment of the instrumented turbine. However, due to different conditions at the wind farm, such as turbulence, differences in water depth and foundation design this turbine will not be fully representable for all turbines in the farm. In this paper we will use the load measurements on two offshore wind turbines in the Northwind offshore wind farm to discuss fatigue progression in an operational wind farm. By calculating the damage equivalent loads on the two turbines the fatigue progression is quantified for every 10 minute interval and can be analyzed against turbulence and site conditions. In future work these results will be used to predict the fatigue life progression in the entire farm.

  1. Satellite winds as a tool for offshore wind resource assessment: The Great Lakes Wind Atlas

    DEFF Research Database (Denmark)

    Doubrawa, Paula; Barthelmie, Rebecca Jane; Pryor, Sara C.

    2015-01-01

    This work presents a new observational wind atlas for the Great Lakes, and proposes a methodology to combine in situ and satellite wind observations for offshore wind resource assessment. Efficient wind energy projects rely on accurate wind resource estimates, which are complex to obtain offshore...... the North American Regional Reanalysis. Generalized wind climates are obtained for each buoy and coastal site with the wind model WAsP, and combined into a single wind speed estimate for the Great Lakes region. The method of classes is used to account for the temporal sparseness in the SAR data set...

  2. Wind for Schools: A Wind Powering America Project

    Science.gov (United States)

    US Department of Energy, 2007

    2007-01-01

    The U.S. Department of Energy's (DOE's) Wind Powering America program (based at the National Renewable Energy Laboratory) sponsors the Wind for Schools Project to raise awareness in rural America about the benefits of wind energy while simultaneously educating college seniors regarding wind energy applications. The three primary project goals of…

  3. Operation Design of Wind Turbines in Strong Wind Conditions

    DEFF Research Database (Denmark)

    Shen, Wen Zhong; Montes, Melissa Barroso; Odgaard, Peter Fogh

    2012-01-01

    and variable speed pitch regulated wind turbines. The variable speed design is more suitable for wind turbines to run at very high wind speeds which can help the turbine braking system to stop the turbine at the new "cut-out" wind speed. Reference power, rotational speed and pitch angle have been designed...

  4. Offshore wind speed and wind power characteristics for ten ...

    Indian Academy of Sciences (India)

    This paper utilizes wind speed data measured at 3 and 10 m above water surface level using buoys at 10 stations in Ionian and Aegean Seas to understand the behaviour of wind and thereafter energy yield at these stations using 5 MW rated power offshore wind turbine. With wind power densities of 971 and 693 W/m2 at ...

  5. Wind Turbine Converter Control Interaction with Complex Wind Farm Systems

    DEFF Research Database (Denmark)

    Kocewiak, Lukasz Hubert; Hjerrild, Jesper; Bak, Claus Leth

    2013-01-01

    in this study. It is shown that wind farm components, such as long high-voltage alternating current cables and park transformers, can introduce significant low-frequency series resonances seen from the wind turbine terminals that can affect wind turbine control system operation and overall wind farm stability...

  6. Sensing the wind profile

    DEFF Research Database (Denmark)

    Pena Diaz, Alfredo

    This thesis consists of two parts. The first is a synopsis of the theoretical progress of the study that is based on a number of journal papers. The papers, which constitute the second part of the report, aim to analyze, measure, and model the wind prole in and beyond the surface layer by combining...... measurements are averaged for several stability conditions and compare well with the surface-layer wind profile. At Høvsøre, it is sufficient to scale the wind speed with the surface friction velocity, whereas at Horns Rev a new scaling is added, due to the variant roughness length. This new scaling is coupled...

  7. Wind Farm Wake

    DEFF Research Database (Denmark)

    Hasager, Charlotte Bay; Karagali, Ioanna; Volker, Patrick

    2017-01-01

    together to investigate the atmospheric conditions at the time of the photos by analysing local meteorological observations and wind turbine information, satellite remote sensing and nearby radiosonde data. Two wake models and one mesoscale model were used to model the case and explain what was seen.......On 25 January 2016 at 12:45 UTC several photographs of the offshore wind farm Horns Rev 2 were taken by helicopter pilot Gitte Lundorff with an iPhone. A very shallow layer of fog covered the sea. The photos of the fog over the sea dramatically pictured the offshore wind farm wake. Researchers got...

  8. Financing renewables - wind energy

    International Nuclear Information System (INIS)

    Armstrong, J.

    1998-01-01

    This paper describes the status of the wind energy markets world-wide, in Europe and in the UK. It outlines the main methods of financing wind energy installations and discusses why different institutional structures have led to different markets in the UK and in Germany, with some concern about the state of the UK onshore industry. The paper looks ahead to the opening up of the potentially much larger offshore wind resource, concluding that in this area, existing UK development and financing structures are well suited. (Author)

  9. Investigating power control in autonomous power systems with increasing wind power penetration

    Energy Technology Data Exchange (ETDEWEB)

    Margaris, Ioannis D. [National Technical Univ. of Athens (Greece). Electric Energy Systems Lab.; Hansen, Anca D.; Sorensen, Poul [Risoe National Laboratory, Roskilde (Denmark). Wind Energy Dept.; Hatziargyriou, Nikos D. [National Technical Univ. of Athens (Greece). Electric Energy Systems Lab.; Public Power Corporation S.A., Athens (Greece)

    2009-07-01

    Increasing levels of wind penetration in autonomous power systems has set intensively high standards with respect to wind turbine technology during the last years. Special features of non-interconnected power systems make security issues rather critical, as the operation of large wind farms like conventional power plants is becoming a necessity. This paper includes the study case of Rhodos island, in Greece, where rapidly increasing wind penetration has started to impose serious security issues for the immediate future. The scenarios studied here correspond to reference year of study 2012 and include wind farms with three different wind turbine technologies - namely Doubly Fed Induction Generator (DFIG), Permanent Magnet Synchronous Generator (PMSG) and Active Stall Induction Generator (ASIG) based wind turbines. Aggregated models of the wind farms are being used and results for different load cases are being analyzed and discussed. The ability of wind farms to assist in some of the power system control services traditionally carried out by conventional synchronous generation is being investigated and discussed. The power grid of the island, including speed governors and automatic voltage regulators, is simulated in the dedicated power system simulation program Power Factory from DIgSILENT. (orig.)

  10. Equivalent models of wind farms by using aggregated wind turbines and equivalent winds

    International Nuclear Information System (INIS)

    Fernandez, L.M.; Garcia, C.A.; Saenz, J.R.; Jurado, F.

    2009-01-01

    As a result of the increasing wind farms penetration on power systems, the wind farms begin to influence power system, and therefore the modeling of wind farms has become an interesting research topic. In this paper, new equivalent models of wind farms equipped with wind turbines based on squirrel-cage induction generators and doubly-fed induction generators are proposed to represent the collective behavior on large power systems simulations, instead of using a complete model of wind farms where all the wind turbines are modeled. The models proposed here are based on aggregating wind turbines into an equivalent wind turbine which receives an equivalent wind of the ones incident on the aggregated wind turbines. The equivalent wind turbine presents re-scaled power capacity and the same complete model as the individual wind turbines, which supposes the main feature of the present equivalent models. Two equivalent winds are evaluated in this work: (1) the average wind from the ones incident on the aggregated wind turbines with similar winds, and (2) an equivalent incoming wind derived from the power curve and the wind incident on each wind turbine. The effectiveness of the equivalent models to represent the collective response of the wind farm at the point of common coupling to grid is demonstrated by comparison with the wind farm response obtained from the detailed model during power system dynamic simulations, such as wind fluctuations and a grid disturbance. The present models can be used for grid integration studies of large power system with an important reduction of the model order and the computation time

  11. Shelter effect on a row of coal piles to prevent wind erosion

    Energy Technology Data Exchange (ETDEWEB)

    Borges, A.R.; Viergas, D.X.

    1988-08-01

    The shelter effect of porous wind breakers over a row of coal piles was studied in a wind tunnel. Two sets of tests are described, one performed in two dimensional configuration in which the shelter effect of several barriers with different heights and porosities is evaluated. The effect of wind direction is considered using a tridimensional model. Wall shear stress measurements performed with a hot film sensor allowed the characterization of the transport properties of fine particles of coal. By integration of the local wind properties the rates of pollutant emission were determined leading to the conclusion of an effective shelter action of the porous wind breakers.

  12. H∞ Based Control for Load Mitigation in Wind Turbines

    Directory of Open Access Journals (Sweden)

    Aron Pujana-Arrese

    2012-04-01

    Full Text Available This article demonstrates a strategy to design multivariable and multi-objective controllers based on the H∞ norm reduction applied to a wind turbine. The wind turbine model has been developed in the GH Bladed software and it is based on a 5 MW wind turbine defined in the Upwind European project. The designed control strategy works in the above rated power production zone and performs generator speed control and load reduction on the drive train and tower. In order to do this, two robust H∞ MISO (Multi-Input Single-Output controllers have been developed. These controllers generate collective pitch angle and generator torque set-point values to achieve the imposed control objectives. Linear models obtained in GH Bladed 4.0 are used, but the control design methodology can be used with linear models obtained from any other modelling package. Controllers are designed by setting out a mixed sensitivity problem, where some notch filters are also included in the controller dynamics. The obtained H∞ controllers have been validated in GH Bladed and an exhaustive analysis has been carried out to calculate fatigue load reduction on wind turbine components, as well as to analyze load mitigation in some extreme cases. The analysis compares the proposed control strategy based on H∞ controllers to a baseline control strategy designed using the classical control methods implemented on the present wind turbines.

  13. Weather response to a large wind turbine array

    Directory of Open Access Journals (Sweden)

    D. B. Barrie

    2010-01-01

    Full Text Available Electrical generation by wind turbines is increasing rapidly, and has been projected to satisfy 15% of world electric demand by 2030. The extensive installation of wind farms would alter surface roughness and significantly impact the atmospheric circulation due to the additional surface roughness forcing. This forcing could be changed deliberately by adjusting the attitude of the turbine blades with respect to the wind, which would enable the "management" of a large array of wind turbines. Using a General Circulation Model (GCM, we represent a continent-scale wind farm as a distributed array of surface roughness elements. Here we show that initial disturbances caused by a step change in roughness grow within four and a half days such that the flow is altered at synoptic scales. The growth rate of the induced perturbations is largest in regions of high atmospheric instability. For a roughness change imposed over North America, the induced perturbations involve substantial changes in the track and development of cyclones over the North Atlantic, and the magnitude of the perturbations rises above the level of forecast uncertainty.

  14. Wind turbine influence on surfers wind conditions at Hanstholm

    DEFF Research Database (Denmark)

    Larsen, Torben J.; Andersen, Søren Juhl

    alter the wind conditions on the lee side, which is an important area for wind and kite surfers. The Dynamic Wake Meander Model is used to investigate the wind conditions north east of the planned new turbines at Hanstholm covering a surf area from a location called “Fish Factory” to a location called...... “Hamborg”. This model, which predicts instationary wind conditions behind one or more wind turbines, has previously been used to predict the changed power and load conditions for wind turbines in wind farm conditions. Avery fine agreement to measurements is seen and the model is therefore considered...

  15. Wind resource estimation and siting of wind turbines

    DEFF Research Database (Denmark)

    Lundtang Petersen, Erik; Mortensen, N.G.; Landberg, L.

    1994-01-01

    Detailed knowledge of the characteristics of the natural wind is necessary for the design, planning and operational aspect of wind energy systems. Here, we shall only be concerned with those meteorological aspects of wind energy planning that are termed wind resource estimation. The estimation...... of the wind resource ranges from the overall estimation of the mean energy content of the wind over a large area - called regional assessment - to the prediction of the average yearly energy production of a specific wind turbine at a specific location - called siting. A regional assessment will most often...

  16. Stress Management: Job Stress

    Science.gov (United States)

    Healthy Lifestyle Stress management Job stress can be all-consuming — but it doesn't have to be. Address your triggers, keep perspective and know when ... effects of stress at work. Effectively coping with job stress can benefit both your professional and personal ...

  17. Operation and control of large wind turbines and wind farms

    Energy Technology Data Exchange (ETDEWEB)

    Soerensen, Poul; Hansen, Anca D.; Thomsen, Kenneth (and others)

    2005-09-01

    This report is the final report of a Danish research project 'Operation and control of large wind turbines and wind farms'. The objective of the project has been to analyse and assess operational strategies and possibilities for control of different types of wind turbines and different wind farm concepts. The potentials of optimising the lifetime/energy production ratio by means of using revised operational strategies for the individual wind turbines are investigated. Different strategies have been simulated, where the power production is decreased to an optimum when taking loads and actual price of produced electricity into account. Dynamic models and control strategies for the wind farms have also been developed, with the aim to optimise the operation of the wind farms considering participation in power system control of power (frequency) and reactive power (voltage), maximise power production, keep good power quality and limit mechanical loads and life time consumption. The project developed models for 3 different concepts for wind farms. Two of the concepts use active stall controlled wind turbines, one with AC connection and one with modern HVDC/VSC connection of the wind farm. The third concept is based on pitch controlled wind turbines using doubly fed induction generators. The models were applied to simulate the behaviour of the wind farm control when they were connected to a strong grid, and some initial simulations were performed to study the behaviour of the wind farms when it was isolated from the main grid on a local grid. Also the possibility to use the available information from the wind turbine controllers to predict the wind speed has been investigated. The main idea has been to predict the wind speed at a wind turbine using up-wind measurements of the wind speed in another wind turbine. (au)

  18. Wind Turbine Acoustics

    Science.gov (United States)

    Hubbard, Harvey H.; Shepherd, Kevin P.

    2009-01-01

    Wind turbine generators, ranging in size from a few kilowatts to several megawatts, are producing electricity both singly and in wind power stations that encompass hundreds of machines. Many installations are in uninhabited areas far from established residences, and therefore there are no apparent environmental impacts in terms of noise. There is, however, the potential for situations in which the radiated noise can be heard by residents of adjacent neighborhoods, particularly those neighborhoods with low ambient noise levels. A widely publicized incident of this nature occurred with the operation of the experimental Mod-1 2-MW wind turbine, which is described in detail elsewhere. Pioneering studies which were conducted at the Mod-1 site on the causes and remedies of noise from wind turbines form the foundation of much of the technology described in this chapter.

  19. 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...

  20. Superconducting wind turbine generators

    DEFF Research Database (Denmark)

    Mijatovic, Nenad

    in this thesis is a part of a larger endeavor, the Superwind project that focused on identifying the potentials that HTS machines could offer to the wind industry and addressing some of the challenges in the process. In order to identify these challenges, I have designed and constructed an HTS machine......A HTS machine could be a way to address some of the technical barriers offshore wind energy is about to face. Due to the superior power density of HTS machines, this technology could become a milestone on which many, including the wind industry, will rely on in the future. The work presented...... experimental setup which is made to serve as precursor, leading towards an optimized HTS machine concept proposed for wind turbines. In part, the work presented in this thesis will focus on the description of the experimental setup and reasoning behind the choices made during the design. The setup comprises...

  1. Wind_Speeds_Master

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set included wind speeds for each subregion in the study (Georges Bank, Gulf of Maine, Southern New England, Middle Atlantic Bight) . The data came from...

  2. South Baltic Wind Atlas

    DEFF Research Database (Denmark)

    Pena Diaz, Alfredo; Hahmann, Andrea N.; Hasager, Charlotte Bay

    A first version of a wind atlas for the South Baltic Sea has been developed using the WRF mesoscale model and verified by data from tall Danish and German masts. Six different boundary-layer parametrization schemes were evaluated by comparing the WRF results to the observed wind profiles...... at the masts. The WRF modeling was done in a nested domain of high spatial resolution for 4 years. In addition the longterm wind statistics using the NCAR-NCEP reanalysis data were performed during 30 years to provide basis for a long-term adjustment of the results and the final WRF results include a weighting...... for the long-term trends variability in the South Baltic Sea. Observations from Earth observing satellites were used to evaluate the spatial resolution of the WRF model results near the surface. The QuikSCAT and the WRF results compared well whereas the Envisat ASAR mean wind map showed some variation...

  3. Noise from wind turbines

    International Nuclear Information System (INIS)

    Andersen, B.; Larsen, P.

    1993-01-01

    Denmark has 3200 wind turbines with an installed maximum capacity of 418MW. The most important Danish research projects into wind turbine noise and the main results are listed. These date from 1983. Two comprehensive studies are currently in progress. The first is an analytical and empirical investigation of aerodynamic noise from wind turbine rotors and has so far dealt mainly with tip noise. The measurement method, using a hard board mounted microphone on the ground near the turbine, is described. Four different tip designs have been tested. Some examples of reference sound power level spectra for three of the designs are presented. During the past two years a computerbased data acquisition system has been used for real-time determination of sound power levels. The second study, which has just commenced, is on annoyance from wind turbine noise. It will include noise measurements, masking calculations and a social survey on the perceived nuisance. (UK)

  4. Aerodynamics of wind turbines

    DEFF Research Database (Denmark)

    Hansen, Martin Otto Laver

    Aerodynamics of Wind Turbines is the established essential text for the fundamental solutions to efficient wind turbine design. Now in its third edition, it has been substantially updated with respect to structural dynamics and control. The new control chapter now includes details on how to design...... a classical pitch and torque regulator to control rotational speed and power, while the section on structural dynamics has been extended with a simplified mechanical system explaining the phenomena of forward and backward whirling modes. Readers will also benefit from a new chapter on Vertical Axis Wind...... Turbines (VAWT). Topics covered include increasing mass flow through the turbine, performance at low and high wind speeds, assessment of the extreme conditions under which the turbine will perform and the theory for calculating the lifetime of the turbine. The classical Blade Element Momentum method...

  5. Wind Profiling Radar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Clutter present in radar return signals as used for wind profiling is substantially removed by carrying out a Daubechies wavelet transformation on a time series of...

  6. Distributed Wind Market Applications

    Energy Technology Data Exchange (ETDEWEB)

    Forsyth, T.; Baring-Gould, I.

    2007-11-01

    Distributed wind energy systems provide clean, renewable power for on-site use and help relieve pressure on the power grid while providing jobs and contributing to energy security for homes, farms, schools, factories, private and public facilities, distribution utilities, and remote locations. America pioneered small wind technology in the 1920s, and it is the only renewable energy industry segment that the United States still dominates in technology, manufacturing, and world market share. The series of analyses covered by this report were conducted to assess some of the most likely ways that advanced wind turbines could be utilized apart from large, central station power systems. Each chapter represents a final report on specific market segments written by leading experts in this field. As such, this document does not speak with one voice but rather a compendium of different perspectives, which are documented from a variety of people in the U.S. distributed wind field.

  7. Wind Tunnel Facility

    Data.gov (United States)

    Federal Laboratory Consortium — This ARDEC facility consists of subsonic, transonic, and supersonic wind tunnels to acquire aerodynamic data. Full-scale and sub-scale models of munitions are fitted...

  8. Aerodynamics of wind turbines

    DEFF Research Database (Denmark)

    Hansen, Martin Otto Laver

    Aerodynamics of Wind Turbines is the established essential text for the fundamental solutions to efficient wind turbine design. Now in its third edition, it has been substantially updated with respect to structural dynamics and control. The new control chapter now includes details on how to design...... Turbines (VAWT). Topics covered include increasing mass flow through the turbine, performance at low and high wind speeds, assessment of the extreme conditions under which the turbine will perform and the theory for calculating the lifetime of the turbine. The classical Blade Element Momentum method...... is also covered, as are eigenmodes and the dynamic behaviour of a turbine. The book describes the effects of the dynamics and how this can be modelled in an aeroelastic code, which is widely used in the design and verification of modern wind turbines. Furthermore, it examines how to calculate...

  9. Monitoring of wind turbines

    Science.gov (United States)

    White, Jonathan R.; Adams, Douglas E.; Paquette, Josh

    2017-07-25

    Method and apparatus for determining the deflection or curvature of a rotating blade, such as a wind turbine blade or a helicopter blade. Also, methods and apparatus for establishing an inertial reference system on a rotating blade.

  10. Performance of Wind Pump Prototype

    African Journals Online (AJOL)

    Mulu

    performance of the wind pump. One year wind speed data collected at 10 m height was extrapolated to the wind pump hub height using wind shear coefficient. The model assumed balanced rotor power and reciprocating pump, hence did not consider the effect of pump size. The theoretical model estimated the average ...

  11. 2010 Wind Technologies Market Report

    Energy Technology Data Exchange (ETDEWEB)

    Ryan Wiser, Mark Bolinger

    2011-06-01

    This report provides a comprehensive overview of trends in the U.S. wind power market in 2010. The report analyzes trends in wind power capacity, industry, manufacturing, turbines, installed project costs, project performance, and wind power prices. It also describes trends among wind power developers, project owners, and power purchasers, and discusses financing issues.

  12. Wind energy: A viable alternative

    International Nuclear Information System (INIS)

    Soin, R.S.

    1991-01-01

    This article examines the economic feasibility of wind energy in the current economic and political environment. The article specifically addresses the wind farm application to India, with asides to Europe and the US. Topics discussed include cost of energy generation for a 10 MW wind farm, cost comparison for captive energy options (diesel, coal, wind), environmental impacts, and social benefits

  13. Integrated Wind Power Planning Tool

    DEFF Research Database (Denmark)

    Rosgaard, Martin H.; Hahmann, Andrea N.; Nielsen, Torben S.

    This poster presents the Public Service Obligation (PSO) funded project PSO 10464 "Integrated Wind Power Planning Tool". The project goal is to integrate a Numerical Weather Prediction (NWP) model with statistical tools in order to assess wind power fluctuations, with focus on short term...... forecasting for existing wind farms, as well as long term power system planning for future wind farms....

  14. Wind energy utilization: A bibliography

    Science.gov (United States)

    1975-01-01

    Bibliography cites documents published to and including 1974 with abstracts and references, and is indexed by topic, author, organization, title, and keywords. Topics include: Wind Energy Potential and Economic Feasibility, Utilization, Wind Power Plants and Generators, Wind Machines, Wind Data and Properties, Energy Storage, and related topics.

  15. Wind flow through shrouded wind turbines

    Science.gov (United States)

    2017-03-01

    velocity and model angle were varied . Additionally, static wall pressures and cross section flow were studied with the addition of a screen. The pressure...the geometry of a wind lens or flange on the shroud and a gradually diverging shape, proved to accelerate the flow through the duct. 14. SUBJECT...Tunnel velocity and model angle were varied . Additionally, static wall pressures and cross section flow were studied with the addition of a screen. The

  16. 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.

  17. Wind energy handbook

    CERN Document Server

    Burton, Tony; Sharpe, David; Bossanyi, Ervin

    2011-01-01

    Named as one of Choice's Outstanding Academic Titles of 2012Every year, Choice subject editors recognise the most significant print and electronic works reviewed in Choice during the previous calendar year. Appearing annually inChoice's January issue, this prestigious list of publications reflects the best in scholarly titles and attracts extraordinary attention from the academic library community. The authoritative reference on wind energy, now fully revised and updated to include offshore wind power<

  18. Wind power barometer

    International Nuclear Information System (INIS)

    2006-01-01

    This annual evaluation is a synthesis of works published in 2006. Comparisons are presented between the wind power performances and European Commission White Paper and Biomass action plan objectives. Germany and Spain are no longer the only countries ensuring European Union market growth. The market sees also a rise in importance of wind power in United Kingdom, Portugal, Italy and France. (A.L.B.)

  19. Wind interviewet til politikken

    DEFF Research Database (Denmark)

    Wind, Marlene

    2017-01-01

    Fredag d. 29. september blev centerleder og professor ved Center for Europæisk Politik Marlene Wind interviewet til Politiken i forbindelse med det tyske forbundsvalgs betydning for EU's fremtid. Mange har spekuleret i om FDP (Freie Demokratische Partei) med deres unægtelige indflydelse på en...... kommende tysk koalition, kommer til at påvirke den tysk-franske alliance i EU-regi. Ikke hvis man spørger Marlene Wind:...

  20. Small wind turbine

    OpenAIRE

    Vélez Castellano, Didier

    2010-01-01

    The main objective is to develop a project on installing a small wind turbine at the University of Glyndwr in Wrexham Wales. Today are immersed in a world seeking clean energy for reduce greenhouse gases because this problem is becoming a global reality. So installing a small wind turbine at the university would provide large quantity of clean energy to supply a workshop and also reduce the expulsion of CO2 into the atmosphere. The main characteristic of the turbine under...

  1. Wind turbine state estimation

    OpenAIRE

    Knudsen, Torben

    2014-01-01

    Dynamic inflow is an effect which is normally not included in the models used for wind turbine control design. Therefore, potential improvement from including this effect exists. The objective in this project is to improve the methods previously developed for this and especially to verify the results using full-scale wind turbine data. The previously developed methods were based on extended Kalman filtering. This method has several drawback compared to unscented Kalman filtering which has the...

  2. Wind turbine reliability analysis

    OpenAIRE

    Pinar Pérez, Jesús María; García Márquez, Fausto Pedro; Tobias, Andrew Mark; Papaelias, Mayorkinos

    2013-01-01

    Against the background of steadily increasing wind power generation worldwide, wind turbine manufacturers are continuing to develop a range of configurations with different combinations of pitch control, rotor speeds, gearboxes, generators and converters. This paper categorizes the main designs, focusing on their reliability by bringing together and comparing data from a selection of major studies in the literature. These are not particularly consistent but plotting failure rates against hour...

  3. Wind Streak and Crater

    Science.gov (United States)

    2004-01-01

    23 February 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a wind streak developed in the lee of a meteor impact crater in western Daedalia Planum. The dominant winds responsible for the streak blew from the bottom/lower right (southeast). The image is located near 9.9oS, 144.9oW. Sunlight illuminates the scene from the lower left; the picture covers an area 3 km (1.9 mi) wide.

  4. Next Generation Wind Turbine

    Energy Technology Data Exchange (ETDEWEB)

    Cheraghi, S. Hossein [Western New England Univ., Springfield, MA (United States); Madden, Frank [FloDesign Wind Turbine Corp., Waltham, MA (United States)

    2012-09-01

    The goal of this collaborative effort between Western New England University's College of Engineering and FloDesign Wind Turbine (FDWT) Corporation to wok on a novel areodynamic concept that could potentially lead to the next generation of wind turbines. Analytical studies and early scale model tests of FDWT's Mixer/Ejector Wind Turbine (MEWT) concept, which exploits jet-age advanced fluid dynamics, indicate that the concept has the potential to significantly reduce the cost of electricity over conventional Horizontal Axis Wind Turbines while reducing land usage. This project involved the design, fabrication, and wind tunnel testing of components of MEWT to provide the research and engineering data necessary to validate the design iterations and optimize system performance. Based on these tests, a scale model prototype called Briza was designed, fabricated, installed and tested on a portable tower to investigate and improve the design system in real world conditions. The results of these scale prototype efforts were very promising and have contributed significantly to FDWT's ongoing development of a product scale wind turbine for deployment in multiple locations around the U.S. This research was mutually beneficial to Western New England University, FDWT, and the DOE by utilizing over 30 student interns and a number of faculty in all efforts. It brought real-world wind turbine experience into the classroom to further enhance the Green Engineering Program at WNEU. It also provided on-the-job training to many students, improving their future employment opportunities, while also providing valuable information to further advance FDWT's mixer-ejector wind turbine technology, creating opportunities for future project innovation and job creation.

  5. Database on Wind Characteristics

    DEFF Research Database (Denmark)

    Højstrup, J.; Ejsing Jørgensen, Hans; Lundtang Petersen, Erik

    1999-01-01

    his report describes the work and results of the project: Database on Wind Characteristics which was sponsered partly by the European Commision within the framework of JOULE III program under contract JOR3-CT95-0061......his report describes the work and results of the project: Database on Wind Characteristics which was sponsered partly by the European Commision within the framework of JOULE III program under contract JOR3-CT95-0061...

  6. Oncogene-induced senescence is part of the tumorigenesis barrier imposed by DNA damage checkpoints

    DEFF Research Database (Denmark)

    Bartkova, Jirina; Rezaei, Nousin; Liontos, Michalis

    2006-01-01

    Recent studies have indicated the existence of tumorigenesis barriers that slow or inhibit the progression of preneoplastic lesions to neoplasia. One such barrier involves DNA replication stress, which leads to activation of the DNA damage checkpoint and thereby to apoptosis or cell cycle arrest......, whereas a second barrier is mediated by oncogene-induced senescence. The relationship between these two barriers, if any, has not been elucidated. Here we show that oncogene-induced senescence is associated with signs of DNA replication stress, including prematurely terminated DNA replication forks...... and senescence markers cosegregate closely. Thus, senescence in human preneoplastic lesions is a manifestation of oncogene-induced DNA replication stress and, together with apoptosis, provides a barrier to malignant progression....

  7. Reliability Analysis of Wind Turbines

    DEFF Research Database (Denmark)

    Toft, Henrik Stensgaard; Sørensen, John Dalsgaard

    2008-01-01

    In order to minimise the total expected life-cycle costs of a wind turbine it is important to estimate the reliability level for all components in the wind turbine. This paper deals with reliability analysis for the tower and blades of onshore wind turbines placed in a wind farm. The limit states......) the reliability level for a wind turbine placed in a wind farm is considered, and wake effects from neighbouring wind turbines is taken into account. An illustrative example with calculation of the reliability for mudline bending of the tower is considered. In the example the design is determined according...

  8. 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....

  9. WindPACT Reference Wind Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Dykes, Katherine L [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Rinker, Jennifer [Former National Renewable Energy Laboratory (NREL) employee

    2018-04-02

    To fully understand how loads and turbine cost scale with turbine size, it is necessary to have identical turbine models that have been scaled to different rated powers. The report presents the WindPACT baseline models, which are a series of four baseline models that were designed to facilitate investigations into the scalings of loads and turbine cost with size. The models have four different rated powers (750 kW, 1.5 MW, 3.0 MW, and 5.0 MW), and each model was designed to its specified rated power using the same design methodology. The models were originally implemented in FAST_AD, the predecessor to NREL's open-source wind turbine simulator FAST, but have yet to be implemented in FAST. This report contains the specifications for all four WindPACT baseline models - including structural, aerodynamic, and control specifications - along with the inherent assumptions and equations that were used to calculate the model parameters. It is hoped that these baseline models will serve as extremely useful resources for investigations into the scalings of costs, loads, or optimization routines.

  10. Social barriers in wind power implementation in The Netherlands: Perceptions of wind power entrepreneurs and local civil servants of institutional and social conditions in realizing wind power projects

    International Nuclear Information System (INIS)

    Agterbosch, Susanne; Glasbergen, Pieter; Vermeulen, Walter J.V.

    2007-01-01

    The primary social factors for the implementation of wind energy projects in a liberalized market are entrepreneurs willing to invest. Understanding conditions that trigger entrepreneurs to invest in these projects, and understanding conditions that determine the chance of success for entrepreneurs to implement and exploit their projects, is vital for setting up effective policies to stimulate wind electricity generation. This paper analyses the way in which wind power entrepreneurs and local civil servants experience social and institutional conditions in the operational process of realizing wind power projects, and their perceptions of policy implications. A groups support system in an electronic board room was used to analyze the perceptions. From the analysis it was concluded that wind power entrepreneurs and civil servants share the opinion that the institutionally embedded power position of local politicians, and the sensitiveness of the local political debate for the popular opinion are most critical for project realization. With regard to the proposed solutions, both groups differ in their approach. Entrepreneurs stress procedural solutions, such as limiting the possibilities to appeal, reducing the complexity of the formal authorization trajectory and using a top down planning approach. Civil servants stress more strategic solutions, such as providing more public information on the necessity of wind power for local politicians and citizens, and community involvement in planning processes. Finally, the analysis explains that steering strategies that have been developed at the national level to solve the planning problems at the operational level do not address the right problems. (author)

  11. 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.

  12. Wind turbines and health

    International Nuclear Information System (INIS)

    Rideout, K.; Copes, R.; Bos, C.

    2010-01-01

    This document summarized the potential health hazards associated with wind turbines, such as noise and low frequency sound, vibration and infrasound; electromagnetic fields (EMF); shadow flicker; and ice throw and structural failure. Various symptoms can be attributed to wind turbines, including dizziness, sleep disruption, and headaches. A review of available research regarding potential health affects to residents living in close proximity to wind turbines showed that the sound level associated with wind turbines at common residential setbacks is not sufficient to damage hearing, but may lead to annoyance and sleep disturbance. Research has shown that wind turbines are not a significant source of EMF exposure, and although shadows caused by the blades may be annoying, they are not likely to cause epileptic seizures at normal operational speeds. The risk of injury from ice throw can be minimized with setbacks of 200 to 400 m. Examples of Canadian wind turbine setback guidelines and regulations were also offered. It was concluded that setbacks and operational guidelines can be utilized in combination to address safety hazards, sound levels, land use issues, and impacts on people. 46 refs., 2 tabs., 2 figs.

  13. European wind turbine catalogue

    International Nuclear Information System (INIS)

    1994-01-01

    The THERMIE European Community programme is designed to promote the greater use of European technology and this catalogue contributes to the fulfillment of this aim by dissemination of information on 50 wind turbines from 30 manufacturers. These turbines are produced in Europe and are commercially available. The manufacturers presented produce and sell grid-connected turbines which have been officially approved in countries where this approval is acquired, however some of the wind turbines included in the catalogue have not been regarded as fully commercially available at the time of going to print. The entries, which are illustrated by colour photographs, give company profiles, concept descriptions, measured power curves, prices, and information on design and dimension, safety systems, stage of development, special characteristics, annual energy production, and noise pollution. Lists are given of wind turbine manufacturers and agents and of consultants and developers in the wind energy sector. Exchange rates used in the conversion of the prices of wind turbines are also given. Information can be found on the OPET network (organizations recognised by the European Commission as an Organization for the Promotion of Energy Technologies (OPET)). An article describes the development of the wind power industry during the last 10-15 years and another article on certification aims to give an overview of the most well-known and acknowledged type approvals currently issued in Europe. (AB)

  14. EDITORIAL: Wind energy

    Science.gov (United States)

    Mann, Jakob; Nørkær Sørensen, Jens; Morthorst, Poul-Erik

    2008-01-01

    Wind energy is rapidly growing. In 2006 the installed generating capacity in the world increased by 25%, a growth rate which has more or less been sustained during the last decade. And there is no reason to believe that this growth will slow significantly in the coming years. For example, the United Kingdom's goal for installed wind turbines by 2020 is 33 GW up from 2 GW in 2006, an average annual growth rate of 22% over that period. More than half of all turbines are installed in Europe, but United States, India and lately China are also rapidly growing markets. The cradle of modern wind energy was set by innovative blacksmiths in rural Denmark. Now the wind provides more than 20% of the electrical power in Denmark, the industry has professionalized and has close ties with public research at universities. This focus issue is concerned with research in wind energy. The main purposes of research in wind energy are to: decrease the cost of power generated by the wind; increase the reliability and predictability of the energy source; investigate and reduce the adverse environmental impact of massive deployment of wind turbines; build research based educations for wind energy engineers. This focus issue contains contributions from several fields of research. Decreased costs cover a very wide range of activities from aerodynamics of the wind turbine blades, optimal site selection for the turbines, optimization of the electrical grid and power market for a fluctuating source, more efficient electrical generators and gears, and new materials and production techniques for turbine manufacturing. The United Kingdom recently started the construction of the London Array, a 1 GW off-shore wind farm east of London consisting of several hundred turbines. To design such a farm optimally it is necessary to understand the chaotic and very turbulent flow downwind from a turbine, which decreases the power production and increases the mechanical loads on other nearby turbines. Also

  15. Wind turbines and health

    Energy Technology Data Exchange (ETDEWEB)

    Rideout, K.; Copes, R.; Bos, C. [National Colaborating Centre for Environmental Health, Vancouver, BC (Canada)

    2010-01-15

    This document summarized the potential health hazards associated with wind turbines, such as noise and low frequency sound, vibration and infrasound; electromagnetic fields (EMF); shadow flicker; and ice throw and structural failure. Various symptoms can be attributed to wind turbines, including dizziness, sleep disruption, and headaches. A review of available research regarding potential health affects to residents living in close proximity to wind turbines showed that the sound level associated with wind turbines at common residential setbacks is not sufficient to damage hearing, but may lead to annoyance and sleep disturbance. Research has shown that wind turbines are not a significant source of EMF exposure, and although shadows caused by the blades may be annoying, they are not likely to cause epileptic seizures at normal operational speeds. The risk of injury from ice throw can be minimized with setbacks of 200 to 400 m. Examples of Canadian wind turbine setback guidelines and regulations were also offered. It was concluded that setbacks and operational guidelines can be utilized in combination to address safety hazards, sound levels, land use issues, and impacts on people. 46 refs., 2 tabs., 2 figs.

  16. Tornado type wind turbines

    Science.gov (United States)

    Hsu, Cheng-Ting

    1984-01-01

    A tornado type wind turbine has a vertically disposed wind collecting tower with spaced apart inner and outer walls and a central bore. The upper end of the tower is open while the lower end of the structure is in communication with a wind intake chamber. An opening in the wind chamber is positioned over a turbine which is in driving communication with an electrical generator. An opening between the inner and outer walls at the lower end of the tower permits radially flowing air to enter the space between the inner and outer walls while a vertically disposed opening in the wind collecting tower permits tangentially flowing air to enter the central bore. A porous portion of the inner wall permits the radially flowing air to interact with the tangentially flowing air so as to create an intensified vortex flow which exits out of the top opening of the tower so as to create a low pressure core and thus draw air through the opening of the wind intake chamber so as to drive the turbine.

  17. The potential of wind farms

    International Nuclear Information System (INIS)

    Hauge Madsen, P.; Lundsager, P.

    1992-09-01

    Papers presented at the European wind energy conference on the potential of wind farms are presented. The aim of the conference was to bring into focus the problems, experiences and potential of the application of wind power in wind power farms as a contribution to the European and global energy supply. It was considered that the interchange of experience among representatives of science, utilities, industry, environment and energy planning, together with those who represent financial and insurance interests, would create a better understanding of all aspects of wind power for its future successful development. The subjects covered concern surveys of national planning and policies regarding wind energy utilization and national and global development of wind turbine arrays. The performance of some individual wind farms is described. Papers also deal with utility and project planning, wind prediction and certification, wind loads and fatigues, wakes, noise and control. (AB)

  18. The potential of wind farms

    International Nuclear Information System (INIS)

    Hauge Madsen, P.; Lundsager, P.

    1992-09-01

    Papers presented at the European wind energy conference on the potential of wind farms are presented. The aim of the conference was to bring into focus the problems, experiences and potential of the application of wind power in wind power farms as a contribution to the European and global energy supply. It was considered that the interchange of experience among representatives of science, utilities, industry, environment and energy planning, together with those who represent financial and insurance interests, would create a better understanding of all aspects of wind power for its future successful development. The subjects covered concern surveys of national planning and policies regarding wind energy utilization and national and global development of wind turbine arrays. The performance of some individual wind farms is described. Papers also deal with utility and project planning, wind prediction and certification, wind loads and fatigus, wakes, noise and control. (AB)

  19. Offshore wind farm repowering optimization

    DEFF Research Database (Denmark)

    Hou, Peng; Enevoldsen, Peter; Hu, Weihao

    2017-01-01

    is focused on optimization of offshore wind farm repowering, which is one option for the wind farm owner at end of life for the offshore wind farm. The LCoE is used as the evaluation index to identify whether it is economical to invest in such a way. In an optimized repowering strategy, different types...... of wind turbines are selected to replace the original wind turbines to reconstruct the wind farm, which is demonstrated to be better than the refurbishment approach which replaces the old wind turbines with the same type. The simulations performed in this research reveal that the reconstructed wind farm......, which consists of multiple types of wind turbine, has a smaller LCoE (10.43%) than the refurbishment approach, which shows the superiority of the proposed method. This research contributes an optimization tool to the wind industry, which consequently drives down the cost of energy produced by offshore...

  20. 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

    The Coastal Ohio Wind Project intends to address problems that impede deployment of wind turbines in the coastal and offshore regions of Northern Ohio. The project evaluates different wind turbine designs and the potential impact of offshore turbines on migratory and resident birds by developing multidisciplinary research, which involves wildlife biology, electrical and mechanical engineering, and geospatial science. Firstly, the project conducts cost and performance studies of two- and three-blade wind turbines using a turbine design suited for the Great Lakes. The numerical studies comprised an analysis and evaluation of the annual energy production of two- and three-blade wind turbines to determine the levelized cost of energy. This task also involved wind tunnel studies of model wind turbines to quantify the wake flow field of upwind and downwind wind turbine-tower arrangements. The experimental work included a study of a scaled model of an offshore wind turbine platform in a water tunnel. The levelized cost of energy work consisted of the development and application of a cost model to predict the cost of energy produced by a wind turbine system placed offshore. The analysis found that a floating two-blade wind turbine presents the most cost effective alternative for the Great Lakes. The load effects studies showed that the two-blade wind turbine model experiences less torque under all IEC Standard design load cases considered. Other load effects did not show this trend and depending on the design load cases, the two-bladed wind turbine showed higher or lower load effects. The experimental studies of the wake were conducted using smoke flow visualization and hot wire anemometry. Flow visualization studies showed that in the downwind turbine configuration the wake flow was insensitive to the presence of the blade and was very similar to that of the tower alone. On the other hand, in the upwind turbine configuration, increasing the rotor blade angle of attack

  1. Extreme winds in the Western North Pacific

    Energy Technology Data Exchange (ETDEWEB)

    Ott, S.

    2006-11-15

    A statistical model for extreme winds in the western North Pacific is developed, the region on the Planet where tropical cyclones are most common. The model is based on best track data derived mostly from satellite images of tropical cyclones. The methods used to estimate surface wind speeds from satellite images is discussed with emphasis on the empirical basis, which, unfortunately, is not very strong. This is stressed by the fact that Japanese and US agencies arrive at markedly different estimates. On the other hand, best track data records cover a long period of time and if not perfect they are at least coherent over time in their imperfections. Applying the the Holland model to the best track data, wind profiles can be assigned along the tracks. From this annual wind speed maxima at any particular point in the region can be derived. The annual maxima, in turn, are fitted to a Gumbel distribution using a generalization Abild's method that allows for data wind collected from multiple positions. The choice of this method is justified by a Monte Carlo simulation comparing it to two other methods. The principle output is a map showing fifty year winds in the region. The method is tested against observed winds from Philippine synoptic stations and fair agreement is found for observed and predicted 48 year maxima. However, the almost biasfree performance of the model could be fortuitous, since precise definitions of 'windspeed' in terms averaging time, height above ground and assumed surface roughness are not available, neither for best tracks nor for the synoptic data. The work has been carried out under Danish Research Agency grant 2104-04-0005 'Offshore wind power' and it also covers the findings and analysis carried out in connection with task 1.6 of the project 'Feasibility Assessment and Capacity Building for Wind Energy Development in Cambodia, The Philippines and Vietnam' during 2005-06 under contract 125-2004 with EU

  2. Transcriptomes Reveal Genetic Signatures Underlying Physiological Variations Imposed by Different Fermentation Conditions in Lactobacillus plantarum

    Science.gov (United States)

    Bongers, Roger S.; van Bokhorst-van de Veen, Hermien; Wiersma, Anne; Overmars, Lex; Marco, Maria L.; Kleerebezem, Michiel

    2012-01-01

    Lactic acid bacteria (LAB) are utilized widely for the fermentation of foods. In the current post-genomic era, tools have been developed that explore genetic diversity among LAB strains aiming to link these variations to differential phenotypes observed in the strains investigated. However, these genotype-phenotype matching approaches fail to assess the role of conserved genes in the determination of physiological characteristics of cultures by environmental conditions. This manuscript describes a complementary approach in which Lactobacillus plantarum WCFS1 was fermented under a variety of conditions that differ in temperature, pH, as well as NaCl, amino acid, and O2 levels. Samples derived from these fermentations were analyzed by full-genome transcriptomics, paralleled by the assessment of physiological characteristics, e.g., maximum growth rate, yield, and organic acid profiles. A data-storage and -mining suite designated FermDB was constructed and exploited to identify correlations between fermentation conditions and industrially relevant physiological characteristics of L. plantarum, as well as the associated transcriptome signatures. Finally, integration of the specific fermentation variables with the transcriptomes enabled the reconstruction of the gene-regulatory networks involved. The fermentation-genomics platform presented here is a valuable complementary approach to earlier described genotype-phenotype matching strategies which allows the identification of transcriptome signatures underlying physiological variations imposed by different fermentation conditions. PMID:22802930

  3. Plasma membrane NADH oxidase of maize roots responds to gravity and imposed centrifugal forces

    Science.gov (United States)

    Bacon, E.; Morre, D. J.

    2001-01-01

    NADH oxidase activities measured with excised roots of dark-grown maize (Zea mays) seedlings and with isolated plasma membrane vesicles from roots of dark-grown maize oscillated with a regular period length of 24 min and were inhibited by the synthetic auxin 2,4-dichlorophenoxyacetic [correction of dichorophenoxyacetic] acid. The activities also responded to orientation with respect to gravity and to imposed centrifugal forces. Turning the roots upside down resulted in stimulation of the activity with a lag of about 10 min. Returning the sections to the normal upright position resulted in a return to initial rates. The activity was stimulated reversibly to a maximum of about 2-fold with isolated plasma membrane vesicles, when subjected to centrifugal forces of 25 to 250 x g for 1 to 4 min duration. These findings are the first report of a gravity-responsive enzymatic activity of plant roots inhibited by auxin and potentially related to the gravity-induced growth response. c2001 Editions scientifiques et medicales Elsevier SAS.

  4. Lower-limb amputee recovery response to an imposed error in mediolateral foot placement.

    Science.gov (United States)

    Segal, Ava D; Klute, Glenn K

    2014-09-22

    Despite walking with a wider step width, amputees remain 20% more likely to fall than non-amputees. Since mediolateral (ML) balance is critical for ambulation and contingent on ML foot placement, we used a ML disturbance to perturb walking balance and explore the influence of prosthetic foot stiffness on balance recovery. Ten transtibial amputees were fit with two commonly prescribed prosthetic feet with differing stiffness characteristics; 12 non-amputees also participated. A perturbation device that released an air burst just before heel strike imposed a repeatable medial or lateral disturbance in foot placement. After a medial disturbance, the first recovery step width was narrowed (pprosthetic limb (-103%), the sound limb (-51%) and non-amputees (-41%) and more than twice as variable. The ML inclination angle remained reduced (-109%) for the prosthetic limb, while the sound limb and non-amputees approached undisturbed levels (pprosthetic medial disturbance versus two steps for the sound limb and for non-amputees. After a lateral disturbance, the first recovery step was widened for the prosthetic limb (+82%), sound limb (+75%), and wider than non-amputees (+51%; pProsthetic feet with different stiffness properties did not have a significant effect. In conclusion, amputee balance was particularly challenged by medial disturbances to the prosthetic limb implying a need for improved interventions that address these balance deficits. Published by Elsevier Ltd.

  5. Optimal Placement of Actors in WSANs Based on Imposed Delay Constraints

    Directory of Open Access Journals (Sweden)

    Chunxi Yang

    2014-01-01

    Full Text Available Wireless Sensor and Actor Networks (WSANs refer to a group of sensors and actors linked by wireless medium to probe environment and perform specific actions. Such certain actions should always be taken before a deadline when an event of interest is detected. In order to provide such services, the whole monitor area is divided into several virtual areas and nodes in the same area form a cluster. Clustering of the WSANs is often pursued to give that each actor acts as a cluster-head. The number of actors is related to the size and the deployment of WSANs cluster. In this paper, we find a method to determine the accurate number of actors which enables them to receive data and take actions in an imposed time-delay. The k-MinTE and the k-MaxTE clustering algorithm are proposed to form the minimum and maximum size of cluster, respectively. In those clustering algorithms, actors are deployed in such a way that sensors could route data to actors within k hops. Then, clusters are arranged by the regular hexagon. At last, we evaluate the placement of actors and results show that our approach is effective.

  6. Imposing Cognitive Constraints on Reference Production: The Interplay Between Speech and Gesture During Grounding.

    Science.gov (United States)

    Masson-Carro, Ingrid; Goudbeek, Martijn; Krahmer, Emiel

    2016-10-01

    Past research has sought to elucidate how speakers and addressees establish common ground in conversation, yet few studies have focused on how visual cues such as co-speech gestures contribute to this process. Likewise, the effect of cognitive constraints on multimodal grounding remains to be established. This study addresses the relationship between the verbal and gestural modalities during grounding in referential communication. We report data from a collaborative task where repeated references were elicited, and a time constraint was imposed to increase cognitive load. Our results reveal no differential effects of repetition or cognitive load on the semantic-based gesture rate, suggesting that representational gestures and speech are closely coordinated during grounding. However, gestures and speech differed in their execution, especially under time pressure. We argue that speech and gesture are two complementary streams that might be planned in conjunction but that unfold independently in later stages of language production, with speakers emphasizing the form of their gestures, but not of their words, to better meet the goals of the collaborative task. Copyright © 2016 Cognitive Science Society, Inc.

  7. Wind turbine control and monitoring

    CERN Document Server

    Luo, Ningsu; Acho, Leonardo

    2014-01-01

    Maximizing reader insights into the latest technical developments and trends involving wind turbine control and monitoring, fault diagnosis, and wind power systems, 'Wind Turbine Control and Monitoring' presents an accessible and straightforward introduction to wind turbines, but also includes an in-depth analysis incorporating illustrations, tables and examples on how to use wind turbine modeling and simulation software.   Featuring analysis from leading experts and researchers in the field, the book provides new understanding, methodologies and algorithms of control and monitoring, comput

  8. Wind Energy Workforce Development & Jobs

    Energy Technology Data Exchange (ETDEWEB)

    Tegen, Suzanne

    2016-11-08

    The United States needs a skilled and qualified wind energy workforce to produce domestic clean power. To assist with wind energy workforce development, the U.S. Department of Energy (DOE) and National Renewable Energy Laboratory are engaged with several efforts.This presentation by Suzanne Tegen describes these efforts, including a wind industry survey, DOE's Wind Career Map, the DOE Wind Vision report, and an in-depth discussion of the Jobs & Economic Development Impacts Model.

  9. Small Wind Site Assessment Guidelines

    Energy Technology Data Exchange (ETDEWEB)

    Olsen, Tim [Advanced Energy Systems LLC, Eugene, OR (United States); Preus, Robert [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2015-09-01

    Site assessment for small wind energy systems is one of the key factors in the successful installation, operation, and performance of a small wind turbine. A proper site assessment is a difficult process that includes wind resource assessment and the evaluation of site characteristics. These guidelines address many of the relevant parts of a site assessment with an emphasis on wind resource assessment, using methods other than on-site data collection and creating a small wind site assessment report.

  10. Performance of spanish wind turbines

    International Nuclear Information System (INIS)

    Lago, C.

    1995-01-01

    In this document we can find a statistical evaluation for the wind energy generation from each spanish wind farm referred to 1994, going on with the work that has been carried out since 1992, by initiative of the Wind Energy Division from Renewable Energy Institute. The purpose of this work is to contribute with interesting information for the wind environment and offer a global view from monthly performances of different wind farms. (Author)

  11. Government installation guidelines for the sustainable development of wind power

    International Nuclear Information System (INIS)

    2007-02-01

    The Government of Quebec has made a commitment to clean renewable energy, including wind power, as part of its sustainable development strategy. However, any proposed projects are subject to conditions imposed by regional municipalities. Municipalities are responsible for urban planning laws with jurisdiction over landscape, noise, public safety, and wildlife. Project proponents must meet both social and environmental criteria to ensure the preservation of the municipal territory and the quality of life. Regulations are in place to ensure economic development occurs in tandem with meeting the energy needs of local and regional communities. 16 refs

  12. 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....

  13. 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.

  14. Relationship of Different Perceived Exertion Scales in Walking or Running with Self-Selected and Imposed Intensity

    Directory of Open Access Journals (Sweden)

    Dias Marcelo Ricardo Cabral

    2014-12-01

    Full Text Available The aims of this study were to: (1 compare the Heart Rate (HR and Rating Perceived Exertion (RPE in training with self-selected and imposed loads, and (2 associate the OMNI-Walk/Run and Borg scales with self-selected and imposed loads, both on a treadmill. Ten trained men (20.3 ± 2.0 years, 75.6 ± 9.8 kg, 175.1 ± 5.1 cm participated in a training program with self-selected load (time and speed individually preferred and another with imposed load (even self-selected time and speed 10% higher. The HR and RPE were measured, every minute of training, by the OMNIWalk/ Run and Borg scales. No significant differences were found in the HR and RPE between training sessions. The correlation between the OMNI-Walk/Run and Borg scales showed a moderate association (r = 0.55 in training with self-selected load and a strong association in imposed load (r = 0.79. In this study, self-selected load induced a suboptimal stimulus to elicit favorable organic adaptations. Moreover, high correlation of OMNI Walk/Run and Borg scales with the imposed load showed that the greater the load of training the best were answers of RPE.

  15. Wind Atlas of Bay of Bengal with Satellite Wind Measurement

    DEFF Research Database (Denmark)

    Nadi, Navila Rahman

    footstep towards offshore wind energy analysis for this region. Generally, it is difficult to find offshore wind data relative to the wind turbine hub heights, therefore a starting point is necessary to identify the possible wind power density of the region. In such scenario, Synthetic aperture radars (SAR......The objective of this study is to obtain appropriate offshore location in the Bay of Bengal, Bangladesh for further development of wind energy. Through analyzing the previous published works, no offshore wind energy estimation has been found here. That is why, this study can be claimed as the first......) have proven useful. In this study, SAR based dataset- ENVISAT ASAR has been used for Wind Atlas generation. Furthermore, a comparative study has been performed with Global Wind Atlas (GWA) to determine a potential offshore wind farm. Additionally, the annual energy production of that offshore windfarm...

  16. Wind power today: 1999 Wind Energy program highlights

    Energy Technology Data Exchange (ETDEWEB)

    Weis-Taylor, Pat

    2000-04-06

    Wind Power Today is an annual publication that provides an overview for the Department of Energy's Wind Energy Program. The purpose of Wind Power Today is to show how DOE's Wind Energy Program supports wind turbine research and deployment in hopes of furthering the advancement of wind technologies that produce clean, low-cost, reliable energy for the 21st century. Content objectives include: Educate readers about the advantages and potential for widespread deployment of wind energy; explain DOE wind energy program objectives and goals; describe program accomplishments in research and application; examine the barriers to widespread deployment; describe benefits of continued research and development; facilitate technology transfer; attract cooperative wind energy projects with industry.

  17. When real life wind speed exceeds design wind assumptions

    Energy Technology Data Exchange (ETDEWEB)

    Winther-Jensen, M.; Joergensen, E.R. [Risoe National Lab., Roskilde (Denmark)

    1999-03-01

    Most modern wind turbines are designed according to a standard or a set of standards to withstand the design loads with a defined survival probability. Mainly the loads are given by the wind conditions on the site defining the `design wind speeds`, normally including extreme wind speeds given as an average and a peak value. The extreme wind speeds are normally (e.g. in the upcoming IEC standard for wind turbine safety) defined as having a 50-year recurrence period. But what happens when the 100 or 10,000 year wind situation hits a wind turbine? Results on wind turbines of wind speeds higher than the extreme design wind speeds are presented based on experiences especially from the State of Gujarat in India. A description of the normal approach of designing wind turbines in accordance with the standards in briefly given in this paper with special focus on limitations and built-in safety levels. Based on that, other possibilities than just accepting damages on wind turbines exposed for higher than design wind speeds are mentioned and discussed. The presentation does not intend to give the final answer to this problem but is meant as an input to further investigations and discussions. (au)

  18. Water deficit imposed by partial irrigation at different plant growth stages of common bean

    International Nuclear Information System (INIS)

    Calvache, M.; Reichardt, K.

    1995-01-01

    The purpose of this study was to identify specific growth stages of common bean crop, at which the plant is less sensitive to water stress so that irrigation can be omitted without significant decrease in biological nitrogen fixation and yield. Two field experiments were conducted at a University experiments station, Tumbaco, Pichincha, Ecuador, on a sandy loam soil ( Typic durustoll ). The climate is warm and dry ( mean air temperature 16 degree Celcius and mean relative humidity 74% ) during the cropping season and rainfall of 123 mm was recorded during the cropping period. The treatments consisted of combinations of 7 irrigation regimes ( I1 = all normal watering; I2 = all stres; I3 = traditional practice; I4 = single stress at vegetation; I5 flowering; I6 = yield formation and I7 = ripening stages ) and 2 levels of applied N ( 20 and 80 kg/ ha ). Differential irrigation was started after 3 uniform irrigations for germination and crop establishment. Soil moisture was monitored with a neutron probe down to 0.60 m depth, before and 24 h after each irrigation. Biological Nitrogen Fixation was calculated using the N- 15 metodology in the 20 kg N/ ha treatment. From the yield data, it can be concluded that treatments which had irrigation deficit had lower yield than those that had suplementary irrigation. The flowering stage was the most sensitive to number of pods and grain yield. Biological Nitrogen Fixation was significantly affected by water stress at flowering and formation stages. The crop water use efficiency ( kg/ m 3 ) was the lowest at flowering period and the yield response factor ( Ky ) was higher in treatments I2 ( all stress ) and I5 (stress at flowering ). Comparing with traditional practice by farmers of the region, only treatments I1 and I7 had 13 and 10 % higher crop water use effeciency. 15 tabs., 7 refs. ( Author )

  19. 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...

  20. Prolonged Decline of Jumbo Squid (Dosidicus gigas) Landings in the Gulf of California is Associated with Chronically low wind Stress and Decreased Chlorophyll a after El Niño 2009-2010

    Science.gov (United States)

    Robinson, C. J.; Gomez-Gutierrez, J.

    2016-02-01

    Dosidicus gigas (jumbo squid) is an ecologically relevant predator in the Gulf of California, Mexico, where it supports an economically valuable fishery. The commercial jumbo squid fishery in the Gulf declined steeply after an El Niño event in 2009-2010, and subsequent landings have remained at historically low levels in the relevant squid fishing centers (Guaymas, Sonora, and Santa Rosalia, Baja California Sur). In this paper, we examined wind speed and satellite chlorophyll a concentrations on the jumbo squid fishing grounds as factors that would be expected to be relevant to this prolonged period of low landings. Analysis from local weather stations, remote sensing and fishery data showed that low jumbo squid landings from 2010 to 2015 occurred during a period abnormally weak winter/spring winds and extremely low chlorophyll a concentrations off the East Guaymas Basin. Results indicate that the squid fishing area in the Guaymas region has been chronically impoverished during this period, and that this area may no longer be a productive habitat for jumbo squid. In response to this decreased productivity, size-at-maturity of jumbo squid showed a drastic decrease over the same period. Results are compared with the effect of El Niño 1997-1998 on the jumbo squid fishery and size-at-maturity of this species in the Gulf of California. The key difference between the recovery phases for El Niño 1997-1998 versus El Niño2009-2010 was the wind intensity as measured in the Guaymas fishing area.

  1. Wind turbine storage systems

    International Nuclear Information System (INIS)

    Ibrahim, H.; Ilinca, A.; Perron, J.

    2005-01-01

    Electric power is often produced in locations far from the point of utilization which creates a challenge in stabilizing power grids, particularly since electricity cannot be stored. The production of decentralized electricity by renewable energy sources offers a greater security of supply while protecting the environment. Wind power holds the greatest promise in terms of environmental protection, competitiveness and possible applications. It is known that wind energy production is not always in phase with power needs because of the uncertainty of wind. For that reason, energy storage is the key for the widespread integration of wind energy into the power grids. This paper proposed various energy storage methods that can be used in combination with decentralized wind energy production where an imbalance exists between electricity production and consumption. Energy storage can play an essential role in bringing value to wind energy, particularly if electricity is to be delivered during peak hours. Various types of energy storage are already in use or are being developed. This paper identified the main characteristics of various electricity storage techniques and their applications. They include stationary or embarked storage for long or short term applications. A comparison of characteristics made it possible to determine which types of electricity storage are best suited for wind energy. These include gravity energy; thermal energy; compressed air energy; coupled storage with natural gas; coupled storage with liquefied gas; hydrogen storage for fuel cells; chemical energy storage; storage in REDOX batteries; storage by superconductive inductance; storage in supercondensers; and, storage as kinetic energy. 21 refs., 21 figs

  2. Global surface wind and flux fields from model assimilation of Seasat data

    Science.gov (United States)

    Atlas, R.; Busalacchi, A. J.; Kalnay, E.; Bloom, S.; Ghil, M.

    1986-01-01

    Procedures for dealiasing Seasat data and developing global surface wind and latent and sensible heat flux fields are discussed. Seasat data from September 20, 1978 was dealiased using the Goddard Laboratory for Atmospheres (GLA) analysis/forecast system. The wind data obtained with the objective GLA forecast model are compared to the data subjectively dealiased by Peteherych et al. (1984) and Hoffman (1982, 1984). The GLA procedure is also verified using simulated Seasat data. The areas of high and low heat fluxes and cyclonic and anticyclonic wind stresses detected in the generated fields are analyzed and compared to climatological fields. It is observed that there is good correlation between the time-averaged analyses of wind stress obtained subjectively and objectively, and the monthly mean wind stress and latent fluxes agree with climatological fields and atmospheric and oceanic features.

  3. Structured Control of LPV Systems with Application to Wind Turbines

    DEFF Research Database (Denmark)

    Adegas, Fabiano Daher; Stoustrup, Jakob

    2012-01-01

    This paper deals with structured control of linear parameter varying systems (LPV) with application to wind turbines. Instead of attempting to reduce the problem to linear matrix inequalities (LMI), we propose to design the controllers via an LMI-based iterative algorithm. The proposed algorithm...... can synthesize structured controllers like decentralized, static output and reduced order output feedback for discrete-time LPV systems. Based on a coordinate decent, it relies on a sufficient matrix inequality condition extended with slack variables to an upper bound on the induced L2-norm...... of the closed-loop system. Algorithms for the computation of feasible as well as optimal controllers are presented. The general case where no restrictions are imposed on the parameter dependence is treated here due to its suitability for modeling wind turbines. A comprehensive numerical example of a gain...

  4. Wind Power Today: 1998 Wind Energy Program Highlights

    Energy Technology Data Exchange (ETDEWEB)

    Tromly, K.

    1999-06-17

    The US Department of Energy's Office of Energy Efficiency and Renewable Energy manages the Federal Wind Energy Program. The mission of the program is to help the US wind industry to complete the research, testing, and field verification needed to fully develop advanced wind technologies that will lead the world in cost-effectiveness and reliability. This publication, printed annually, provides a summary of significant achievements in wind energy made during the previous calendar year. Articles include wind energy in the Midwest, an Alaskan wind energy project, the US certification program, structural testing, and the federal program in review.

  5. The Wind Integration National Dataset (WIND) toolkit (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Caroline Draxl: NREL

    2014-01-01

    Regional wind integration studies require detailed wind power output data at many locations to perform simulations of how the power system will operate under high penetration scenarios. The wind datasets that serve as inputs into the study must realistically reflect the ramping characteristics, spatial and temporal correlations, and capacity factors of the simulated wind plants, as well as being time synchronized with available load profiles.As described in this presentation, the WIND Toolkit fulfills these requirements by providing a state-of-the-art national (US) wind resource, power production and forecast dataset.

  6. A critical role of lateral hypothalamus in context-induced relapse to alcohol seeking after punishment-imposed abstinence.

    Science.gov (United States)

    Marchant, Nathan J; Rabei, Rana; Kaganovsky, Konstantin; Caprioli, Daniele; Bossert, Jennifer M; Bonci, Antonello; Shaham, Yavin

    2014-05-28

    In human alcoholics, abstinence is often self-imposed, despite alcohol availability, because of the negative consequences of excessive use. During abstinence, relapse is often triggered by exposure to contexts associated with alcohol use. We recently developed a rat model that captures some features of this human condition: exposure to the alcohol self-administration environment (context A), after punishment-imposed suppression of alcohol self-administration in a different environment (context B), provoked renewal of alcohol seeking in alcohol-preferring P rats. The mechanisms underlying context-induced renewal of alcohol seeking after punishment-imposed abstinence are unknown. Here, we studied the role of the lateral hypothalamus (LH) and its forebrain projections in this effect. We first determined the effect of context-induced renewal of alcohol seeking on Fos (a neuronal activity marker) expression in LH. We next determined the effect of LH reversible inactivation by GABAA + GABAB receptor agonists (muscimol + baclofen) on this effect. Finally, we determined neuronal activation in brain areas projecting to LH during context-induced renewal tests by measuring double labeling of the retrograde tracer cholera toxin subunit B (CTb; injected in LH) with Fos. Context-induced renewal of alcohol seeking after punishment-imposed abstinence was associated with increased Fos expression in LH. Additionally, renewal was blocked by muscimol + baclofen injections into LH. Finally, double-labeling analysis of CTb + Fos showed that context-induced renewal of alcohol seeking after punishment-imposed abstinence was associated with selective activation of accumbens shell neurons projecting to LH. The results demonstrate an important role of LH in renewal of alcohol seeking after punishment-imposed abstinence and suggest a role of accumbens shell projections to LH in this form of relapse. Copyright © 2014 the authors 0270-6474/14/347447-11$15.00/0.

  7. Wind power production: from the characterisation of the wind resource to wind turbine technologies

    International Nuclear Information System (INIS)

    Beslin, Guy; Multon, Bernard

    2016-01-01

    Illustrated by graphs and tables, this article first describes the various factors and means related to the assessment of wind resource in the World, in Europe, and the factors which characterize a local wind resource. In this last respect, the authors indicate how local topography is taken into account to calculate wind speed, how time variations are taken into account (at the yearly, seasonal or daily level), the different methods used to model a local wind resource, how to assess the power recoverable by a wind turbine with horizontal axis (notion of Betz limit). In the second part, the authors present the different wind turbines, their benefits and drawbacks: vertical axis, horizontal axis (examples of a Danish-type wind turbine, of wind turbines designed for extreme conditions). Then, they address the technology of big wind turbines: evolution of technology and of commercial offer, aerodynamic characteristics of wind turbine and benefit of a varying speed (technological solutions, importance of the electric generator). They describe how to choose a wind turbine, how product lines are organised, how the power curve and energy capacity are determined. The issue of integration of wind energy into the power system is then addressed. The next part addressed the economy of wind energy production (annualized production cost, order of magnitude of wind electric power production cost). Future trends are discussed and offshore wind energy production is briefly addressed

  8. Possible Weakening Processes Imposed on California's Earthen Levees under Protracted Drought

    Science.gov (United States)

    Robinson, J. D.; Vahedifard, F.; AghaKouchak, A.

    2015-12-01

    California is currently suffering from a multiyear extreme drought and the impacts of the drought are anticipated to worsen in a warming climate. The resilience of critical infrastructure under extreme drought conditions is a major concern which has not been well understood. Thus, there is a crucial need to improve our understanding about the potential threats of drought on infrastructure and take subsequent actions in a timely manner to mitigate these threats and adopt our infrastructure for forthcoming extreme events. The need is more pronounced for earthen levees, since their functionality to protect limited water resources and dryland is more critical during drought. A significant amount of California's levee systems are currently operating under a high risk condition. Protracted drought can further threaten the structural competency of these already at-risk levee systems through several thermo-hydro mechanical weakening processes that undermine their stability. Viable information on the implications of these weakening processes, particularly on California's earthen levees, is relatively incomplete. This article discusses, from a geotechnical engineering perspective, how California's protracted drought might threaten the integrity of levee systems through the imposition of several thermo-hydro mechanical weakening processes. Pertinent facts and statistics regarding the drought in California are presented and discussed. Catastrophic levee failures and major damages resulting from drought-induce weakening processes such as shear strength reduction, desiccation cracking, land subsidence and surface erosion, fissuring and soil softening, and soil carbon oxidation are discussed to illustrate the devastating impacts that the California drought might impose on existing earthen levees. This article calls for further research in light of these potential drought-inducing weakening mechanisms to support mitigation strategies for reducing future catastrophic levee failures.

  9. Granulocytes impose a tight bottleneck upon the gut luminal pathogen population during Salmonella typhimurium colitis.

    Directory of Open Access Journals (Sweden)

    Lisa Maier

    2014-12-01

    Full Text Available Topological, chemical and immunological barriers are thought to limit infection by enteropathogenic bacteria. However, in many cases these barriers and their consequences for the infection process remain incompletely understood. Here, we employed a mouse model for Salmonella colitis and a mixed inoculum approach to identify barriers limiting the gut luminal pathogen population. Mice were infected via the oral route with wild type S. Typhimurium (S. Tm and/or mixtures of phenotypically identical but differentially tagged S. Tm strains ("WITS", wild-type isogenic tagged strains, which can be individually tracked by quantitative real-time PCR. WITS dilution experiments identified a substantial loss in tag/genetic diversity within the gut luminal S. Tm population by days 2-4 post infection. The diversity-loss was not attributable to overgrowth by S. Tm mutants, but required inflammation, Gr-1+ cells (mainly neutrophilic granulocytes and most likely NADPH-oxidase-mediated defense, but not iNOS. Mathematical modelling indicated that inflammation inflicts a bottleneck transiently restricting the gut luminal S. Tm population to approximately 6000 cells and plating experiments verified a transient, inflammation- and Gr-1+ cell-dependent dip in the gut luminal S. Tm population at day 2 post infection. We conclude that granulocytes, an important clinical hallmark of S. Tm-induced inflammation, impose a drastic bottleneck upon the pathogen population. This extends the current view of inflammation-fuelled gut-luminal Salmonella growth by establishing the host response in the intestinal lumen as a double-edged sword, fostering and diminishing colonization in a dynamic equilibrium. Our work identifies a potent immune defense against gut infection and reveals a potential Achilles' heel of the infection process which might be targeted for therapy.

  10. Imposed visual feedback delay of an action changes mass perception based on the sensory prediction error

    Directory of Open Access Journals (Sweden)

    Takuya eHonda

    2013-10-01

    Full Text Available While performing an action, the timing of when the sensory feedback is given can be used to establish the causal link between the action and its consequence. It has been shown that delaying the visual feedback while carrying an object makes people feel the mass of the object to be greater, suggesting that the feedback timing can also impact the perceived quality of an external object. In this study, we investigated the origin of the feedback timing information that influences the mass perception of the external object.Participants made a straight reaching movement while holding a manipulandum. The movement of the manipulandum was presented as a cursor movement on a monitor. In Experiment 1, various delays were imposed between the actual trajectory and the cursor movement. The participants’ perceived mass of the manipulandum significantly increased as the delay increased to 400 ms, but this gain did not reach significance when the delay was 800 ms. This suggests the existence of a temporal tuning mechanism for incorporating the visual feedback into the perception of mass. In Experiment 2, we examined whether the increased mass perception during the visual delay was due to the prediction error of the visual consequence of an action or to the actual delay of the feedback itself. After the participants adapted to the feedback delay, the perceived mass of the object became lighter than before, indicating that updating the temporal prediction model for the visual consequence diminishes the overestimation of the object’s mass. We propose that the misattribution of the visual delay into mass perception is induced by the sensorimotor prediction error, possibly when the amount of delay (error is within the range that can reasonably include the consequence of an action.

  11. Risk preferences impose a hidden distortion on measures of choice impulsivity.

    Directory of Open Access Journals (Sweden)

    Silvia Lopez-Guzman

    Full Text Available Measuring temporal discounting through the use of intertemporal choice tasks is now the gold standard method for quantifying human choice impulsivity (impatience in neuroscience, psychology, behavioral economics, public health and computational psychiatry. A recent area of growing interest is individual differences in discounting levels, as these may predispose to (or protect from mental health disorders, addictive behaviors, and other diseases. At the same time, more and more studies have been dedicated to the quantification of individual attitudes towards risk, which have been measured in many clinical and non-clinical populations using closely related techniques. Economists have pointed to interactions between measurements of time preferences and risk preferences that may distort estimations of the discount rate. However, although becoming standard practice in economics, discount rates and risk preferences are rarely measured simultaneously in the same subjects in other fields, and the magnitude of the imposed distortion is unknown in the assessment of individual differences. Here, we show that standard models of temporal discounting -such as a hyperbolic discounting model widely present in the literature which fails to account for risk attitudes in the estimation of discount rates- result in a large and systematic pattern of bias in estimated discounting parameters. This can lead to the spurious attribution of differences in impulsivity between individuals when in fact differences in risk attitudes account for observed behavioral differences. We advance a model which, when applied to standard choice tasks typically used in psychology and neuroscience, provides both a better fit to the data and successfully de-correlates risk and impulsivity parameters. This results in measures that are more accurate and thus of greater utility to the many fields interested in individual differences in impulsivity.

  12. Human health safety evaluation of cosmetics in the EU: a legally imposed challenge to science.

    Science.gov (United States)

    Pauwels, M; Rogiers, V

    2010-03-01

    As stated in the European legislation, cosmetic products present on the European market must be safe for the consumer. Safety evaluation of the products is carried out by a qualified safety assessor who needs to consider potential exposure scenarios next to the physicochemical and toxicological profiles of all composing ingredients. Whereas, until recently, the tools to determine the toxicological profile of cosmetic ingredients mainly consisted of animal experiments, they have now been narrowed down substantially by the legally imposed animal testing ban on cosmetic ingredients, taken up in the Cosmetic Products Directive (76/768/EEC). This Directive, however, is not a stand-alone piece of European legislation, since as well directly as indirectly it is influenced by a complex web of related legislations. Vertical legislations deal with different categories of chemicals, including dangerous substances, biocides, plant protection products, food additives, medicinal products, and of course also cosmetics. Horizontal legislative texts, on the contrary, cover more general fields such as protection of experimental animals, consumer product safety, misleading of consumers, specific provisions for aerosols, and others. Experience has learnt that having a general overview of these related legislations is necessary to understand their impact on the cosmetic world in general terms and on cosmetic safety evaluation in particular. This goes for a variety of concerned parties, including national and European regulators/agencies, contract laboratories, raw material suppliers, cosmetic companies, research and educational centers. They all deal with a number of aspects important for the quality and toxicity of cosmetics and their ingredients. This review summarises the most relevant points of the legislative texts of different types of product categories and emphasises their impact on the safety evaluation of cosmetics.

  13. Convection patterns in a liquid metal under an imposed horizontal magnetic field.

    Science.gov (United States)

    Yanagisawa, Takatoshi; Hamano, Yozo; Miyagoshi, Takehiro; Yamagishi, Yasuko; Tasaka, Yuji; Takeda, Yasushi

    2013-12-01

    We performed laboratory experiments of Rayleigh-Bénard convection with liquid gallium under various intensities of a uniform imposed horizontal magnetic field. An ultrasonic velocity profiling method was used to visualize the spatiotemporal structure of the flows with simultaneous monitoring of the temperature fluctuations in the liquid gallium layer. The explored Rayleigh numbers Ra range from the critical value for onset of convection to 10(5); the Chandrasekhar number Q covers values up to 1100. A regime diagram of the convection patterns was established in relation to the Ra and Q values for a square vessel with aspect ratio 5. We identified five flow regimes: (I) a fluctuating large-scale pattern without rolls, (II) weakly constrained rolls with fluctuations, (III) a continuous oscillation of rolls, (IV) repeated roll number transitions with random reversals of the flow direction, and (V) steady two-dimensional (2D) rolls. These flow regimes are classified by the Ra/Q values, the ratio of the buoyancy to the Lorentz force. Power spectra from the temperature time series indicate that regimes I and II have the features of developed turbulence, while the other regimes do not. The region of steady 2D rolls (Busse balloon) extends to high Ra values in the present setting by a horizontal magnetic field and regime V is located inside the Busse balloon. Concerning the instabilities of the steady 2D rolls, regime III is the traveling wave convection developed from the oscillatory instability. Regime IV can be regarded as a state of phase turbulence, which is induced by intermittent occurrences of the skewed-varicose instability.

  14. Assessment of the sensory and physical limitations imposed by leprosy in a Brazilian Amazon Population

    Directory of Open Access Journals (Sweden)

    Cintia Yolette Urbano Pauxis Aben-Athar

    Full Text Available Abstract INTRODUCTION Leprosy often results in sensory and physical limitations. This study aimed to evaluate these limitations using a quantitative approach in leprosy patients in Belém (Pará, Brazil. METHODS This epidemiological, cross-sectional study measured the sensory impairment of smell and taste through the use of a questionnaire and evaluated activity limitations of daily life imposed by leprosy through the Screening of Activity Limitation and Safety Awareness (SALSA Scale. Data were collected from 84 patients and associations between the degree of disability and clinical and epidemiological characteristics were assessed. RESULTS The majority of patients were men (64.3%, married (52.4%, age 31-40 years old (26.2%, had primary education (50%, and were independent laborers (36.9%. The multibacillary operational classification (81%, borderline clinical form (57.1%, and 0 degrees of physical disability (41.7% were predominant. SALSA scores ranged from 17 to 59 points, and being without limitations was predominant (53.6%. The risk awareness score ranged from 0 to 8, with a score of 0 (no awareness of risk being the most common (56%. Evaluation of smell and taste sensory sensitivities revealed that 70.2% did not experience these sensory changes. Patients with leprosy reactions were 7 times more likely to develop activity limitations, and those who had physical disabilities were approximately four times more likely to develop a clinical picture of activity limitations. CONCLUSIONS Most patients showed no sensory changes, but patients with leprosy reactions were significantly more likely to develop activity limitations. Finally, further studies should be performed, assessing a higher number of patients to confirm the present results.

  15. Human health safety evaluation of cosmetics in the EU: A legally imposed challenge to science

    International Nuclear Information System (INIS)

    Pauwels, M.; Rogiers, V.

    2010-01-01

    As stated in the European legislation, cosmetic products present on the European market must be safe for the consumer. Safety evaluation of the products is carried out by a qualified safety assessor who needs to consider potential exposure scenarios next to the physicochemical and toxicological profiles of all composing ingredients. Whereas, until recently, the tools to determine the toxicological profile of cosmetic ingredients mainly consisted of animal experiments, they have now been narrowed down substantially by the legally imposed animal testing ban on cosmetic ingredients, taken up in the Cosmetic Products Directive (76/768/EEC). This Directive, however, is not a stand-alone piece of European legislation, since as well directly as indirectly it is influenced by a complex web of related legislations. Vertical legislations deal with different categories of chemicals, including dangerous substances, biocides, plant protection products, food additives, medicinal products, and of course also cosmetics. Horizontal legislative texts, on the contrary, cover more general fields such as protection of experimental animals, consumer product safety, misleading of consumers, specific provisions for aerosols, and others. Experience has learnt that having a general overview of these related legislations is necessary to understand their impact on the cosmetic world in general terms and on cosmetic safety evaluation in particular. This goes for a variety of concerned parties, including national and European regulators/agencies, contract laboratories, raw material suppliers, cosmetic companies, research and educational centers. They all deal with a number of aspects important for the quality and toxicity of cosmetics and their ingredients. This review summarises the most relevant points of the legislative texts of different types of product categories and emphasises their impact on the safety evaluation of cosmetics.

  16. Aeroservoelasticity of wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Skovmose Kallesoee, B.

    2007-12-14

    This thesis deals with the fundamental aeroelastic interaction between structural motion, Pitch action and control for a wind turbine blade. As wind turbines become larger, the interaction between pitch action, blade motion, aerodynamic forces, and control become even more important to understand and address. The main contribution of this thesis is the development of an aeroelastic blade model which on the one hand includes the important effects of steady state blade deformation, gravity and pitch action, and on the other it is transparent, suitable for analytical analysis and parameter studies, and furthermore linear and therefore suitable for control design. The development of the primary aeroelastic blade model is divided into four steps: 1) Nonlinear partial differential equations (PDEs) of structural blade motion are derived together with equations of pitch action and rotor speed; the individual terms in these equations are discussed and given physical interpretations; 2) Steady state blade deformation and induced velocities are computed by combining the PDEs with a steady state aerodynamic model; 3) Aeroelastic modes of motion are computed by combining the linearized PDEs with a linear unsteady aerodynamic model; this model is used to analyze how blade deformation effects the modes of motion; and 4) the linear aeroelastic blade model is derived by a modal expansion of the linearized PDEs combined with a linear unsteady aerodynamic model. The aeroelastic blade model has many similarities to a 2D blade section model, and it can be used instead of this in many applications, giving a transparent connection to a real wind turbine blade. In this work the aeroelastic blade model is used to analyze interaction between pitch action, blade motion and wind speed variations. Furthermore the model is used to develop a state estimator for estimating the wind speed and wind shear, and to suggest a load reducing controller. The state estimator estimates the wind shear very

  17. Intermittent heating of the corona as an alternative to generate fast solar wind flows

    International Nuclear Information System (INIS)

    Grappin, R.; Mangeney, A.; Schwartz, S.J.; Feldman, W.C.

    1999-01-01

    We discuss a new alternative to the generation of fast streams which does not require momentum addition beyond the critical point. We consider the consequences on the solar wind of temporally intermittent heat depositions at the base of the wind. With the help of 1d hydrodynamic simulations we show that the instantaneous wind velocity profile fluctuates around an average profile well above the one corresponding to the Parker solution with a coronal temperature equal to the average coronal temperature imposed at the bottom of the numerical domain. The origin of this result lies in a previously overlooked phenomenon, the overexpansion of hot plasma regions in the subsonic wind. copyright 1999 American Institute of Physics

  18. Wind Farms: Modeling and Control

    DEFF Research Database (Denmark)

    Soleimanzadeh, Maryam

    2012-01-01

    is minimized. The controller is practically feasible. Yet, the results on load reduction in this approach are not very significant. In the second strategy, the wind farm control problem has been divided into below rated and above rated wind speed conditions. In the above rated wind speed pitch angle and power....... Distributed controller design commences with formulating the problem, where a structured matrix approach has been put in to practice. Afterwards, an H2 control problem is implemented to obtain the controller dynamics for a wind farm such that the structural loads on wind turbines are minimized.......The primary purpose of this work is to develop control algorithms for wind farms to optimize the power production and augment the lifetime of wind turbines in wind farms. In this regard, a dynamical model for wind farms was required to be the basis of the controller design. In the first stage...

  19. Wind energy potential in India

    International Nuclear Information System (INIS)

    Rangarajan, S.

    1995-01-01

    Though located in the tropics, India is endowed with substantial wind resources because of its unique geographical location which gets fully exposed to both the south-west and north-east monsoon winds. The westerly winds of the south-west monsoons provide bulk of the wind potential. Areas with mean annual wind speed exceeding 18 k mph and areas with mean annual power density greater than 140 W/m 2 have been identified using the wind data collected by the wind monitoring project funded by the Ministry of Non-conventional Energy Sources (MNES). Seasonal variations in wind speed at selected locations are discussed as also the frequency distribution of hourly wind speed. Annual capacity factors for 250 kW wind electric generators have been calculated for several typical locations. A good linear correlation has been found between mean annual wind speed and mean annual capacity factor. A method is described for assessing wind potential over an extended region where adequate data is available. It is shown that the combined wind energy potential over five selected areas of limited extent in Gujarat, Andhra Pradesh and Tamil Nadu alone amounts to 22,000 MW under the assumption of 20 per cent land availability for installing wind farms. For a higher percentage of land availability, the potential will be correspondingly higher. (author). 12 refs., 6 figs., 3 tabs

  20. Wind power barometer

    International Nuclear Information System (INIS)

    Anon.

    2010-01-01

    The global wind power market not only repelled the strictures of the financial crisis, but saw the installation of 37 GW in 2009, which is almost 10 GW up on 2008. China and the United States registered particularly steady growth and the European Union also picked up momentum to break its installation record. A total capacity of 158 GW of wind power are now installed across the world from which 74.8 GW in the European Union. Among the European countries Denmark has the highest wind capacity per inhabitant in 2009: 627.5 kW/1000 inhabitants. Spain seeks to limit its market's growth in order to better manage the development of wind energy across the country. German growth is back, Italy chalks up a new record for installation and the French market is becoming increasingly regulated. United-Kingdom is developing offshore wind farms: the offshore capacity could reasonably rise to 20000 MW by 2020. The last part of the article reports some economical news from the leading players: Vestas, GE-Energy, Gamesa, Enercon, Sinovel and Siemens. (A.C.)

  1. Wind Powering America

    International Nuclear Information System (INIS)

    Flowers, L.; Dougherty, P. J.

    2001-01-01

    At the June 1999 Windpower Conference, the Secretary of Energy launched the Office of Energy Efficiency and Renewable Energy's Wind Powering America (WPA) initiative. The goals of the initiative are to meet 5% of the nation's energy needs with wind energy by 2020 (i.e., 80,000 megawatts installed), to double the number of states that have more than 20 megawatts (MW) of wind capacity to 16 by 2005 and triple it to 24 by 2010, and to increase wind's contribution to Federal electricity use to 5% by 2010. To achieve the Federal government's goal, DOE would take the leadership position and work with its Federal partners. Subsequently, the Secretary accelerated the DOE 5% commitment to 2005. Achieving the 80,000 MW goal would result in approximately$60 billion investment and$1.5 billion of economic development in our rural areas (where the wind resources are the greatest). The purpose of this paper is to provide an update on DOE's strategy for achieving its goals and the activities it has undertaken since the initiative was announced

  2. Wind Powering America

    Energy Technology Data Exchange (ETDEWEB)

    Flowers, L. (NREL); Dougherty, P. J. (DOE)

    2001-07-07

    At the June 1999 Windpower Conference, the Secretary of Energy launched the Office of Energy Efficiency and Renewable Energy's Wind Powering America (WPA) initiative. The goals of the initiative are to meet 5% of the nation's energy needs with wind energy by 2020 (i.e., 80,000 megawatts installed), to double the number of states that have more than 20 megawatts (MW) of wind capacity to 16 by 2005 and triple it to 24 by 2010, and to increase wind's contribution to Federal electricity use to 5% by 2010. To achieve the Federal government's goal, DOE would take the leadership position and work with its Federal partners. Subsequently, the Secretary accelerated the DOE 5% commitment to 2005. Achieving the 80,000 MW goal would result in approximately $60 billion investment and $1.5 billion of economic development in our rural areas (where the wind resources are the greatest). The purpose of this paper is to provide an update on DOE's strategy for achieving its goals and the activities it has undertaken since the initiative was announced.

  3. 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.

  4. Wind energy and Turkey.

    Science.gov (United States)

    Coskun, Aynur Aydin; Türker, Yavuz Özhan

    2012-03-01

    The global energy requirement for sustaining economic activities, meeting social needs and social development is increasing daily. Environmentally friendly, renewable energy resources are an alternative to the primary non-renewable energy resources, which devastate ecosystems in order to meet increasing demand. Among renewable energy sources such as hydropower, biopower, geothermal power and solar power, wind power offers distinct advantages to Turkey. There is an increasing tendency toward wind globally and the European Union adjusted its legal regulations in this regard. As a potential EU Member state, Turkey is going through a similar process. The number of institutional and legal regulations concerning wind power has increased in recent years; technical infrastructure studies were completed, and some important steps were taken in this regard. This study examines the way in which Turkey has developed support for wind power, presents a SWOT analysis of the wind power sector in Turkey and a projection was made for the concrete success expected to be accomplished in the future.

  5. 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)

  6. Aspects of the determination of winds by means of scatterometry and of the utilization of vector wind data for meteorological forecasts

    Science.gov (United States)

    Pierson, W. J., Jr.; Sylvester, W. B.; Donelan, M. A.

    1986-01-01

    The present paper provides a description of four aspects of scatterometer winds and their uses. The theory of wave generation by the wind is considered along with an analysis of the properties of superobservations, and studies of intermittent versus continuous data assimilation methods for numerical weather predictions which use remotely sensed data. A comparison of the sum of squares versus the maximum likelihood method for recovering the vector winds is also conducted. Questions regarding wind speed, friction velocity, or normal stress are discussed and synoptic scale fields from Seasat-SASS data are examined.

  7. Wind power; Die Kraft der Winde

    Energy Technology Data Exchange (ETDEWEB)

    Mardo, Dietrich

    2009-10-30

    Wind power plants are probably only one pillar of the bridge that is taking us into an energy future still unimaginable to us. They are extremely cost-intensive and bulky and they spoil our landscapes. Their patronage by political leaders is understandable considering our excessive dependence on oil and gas. True energy autonomy is currently still a utopian dream for a country as poor in resources as Germany. On the other hand, to reach Utopia you have to build bridges there. Seen this way all currently available types of renewable energy represent bridge technologies whose realisation is imperative.

  8. Experimental evidence that litter size imposes an oxidative challenge to offspring.

    Science.gov (United States)

    Gibson, Alyssa B; Garratt, Michael; Brooks, Robert C

    2015-12-01

    The post-natal environment in which young develop can substantially impact development, adult phenotype and fitness. In wild mice, competition among litter-mates affects development rate and adult behaviour. We manipulated post-natal litter size in a cross-fostering design to investigate the effects of enlarged and reduced litter sizes on sexual signalling, oxidative stress and the links between them. Oxidative stress causes somatic damage that can limit reproductive success and lifespan, and is predicted to mediate investment in life-history traits, including sexual signals. We predicted that litter enlargement would cause an increase in potential oxidative stress, inhibit growth and reduce sexual signalling in male mice. Males reared in enlarged litters were smaller at weaning and, despite rapid growth immediately after weaning, remained smaller at 10 weeks of age than those reared in smaller litters. Females from enlarged litters were consistently smaller throughout post-weaning development and showed no increase in growth rate compared with females from reduced litters. In enlarged litters, protein thiol concentration was lower at weaning in the liver and kidneys, with this trend continuing at 10 weeks of age in the kidneys only. Aconitase enzyme activity was also lower in mice from enlarged litters at weaning and 10 weeks of age in the kidneys. Male mice from enlarged litters scent marked more frequently and had larger preputial glands than those from reduced litters, indicating greater sexual signalling investment irrespective of this increased oxidative challenge. The results of this study are the first to reveal oxidative costs of developmental stress in small mammals. © 2015. Published by The Company of Biologists Ltd.

  9. The wind energy takes off

    International Nuclear Information System (INIS)

    Rapin, M.; Degobert, Ph.

    2010-01-01

    After having evoked the objectives defined for wind energy production by 2050, the important growth of wind energy in Europe and in other parts of the world, and its importance in terms of business and jobs, this article presents the Denmark model where the wind energy industry is a world leader but now faces the need of a new development model. It comments the investments and incentives implemented in Western countries after the first oil crisis. It outlines the increasing power of wind generators and their technological evolution, the development of offshore wind farms and their cost, and finally the intermittency problem and the case of small wind turbines

  10. Wind turbines and idiopathic symptoms

    DEFF Research Database (Denmark)

    Blanes-Vidal, Victoria; Schwartz, Joel

    2016-01-01

    Whether or not wind turbines pose a risk to human health is a matter of heated debate. Personal reactions to other environmental exposures occurring in the same settings as wind turbines may be responsible of the reported symptoms. However, these have not been accounted for in previous studies. We...... investigated whether there is an association between residential proximity to wind turbines and idiopathic symptoms, after controlling for personal reactions to other environmental co-exposures. We assessed wind turbine exposures in 454 residences as the distance to the closest wind turbine (Dw) and number...... of wind turbines

  11. Simulation of a flexible wind turbine response to a grid fault

    DEFF Research Database (Denmark)

    Hansen, Anca Daniela; Cutululis, Nicolaos Antonio; Sørensen, Poul Ejnar

    2007-01-01

    The purpose of this work is to illustrate the impact of a grid fault on the mechanical loads of a wind turbine. Grid faults generate transients in the generator electromagnetic torque, which are propagated in the wind turbine, stressing its mechanical components. Grid faults are normally simulated...... in power system simulation tools applying simplified mechanical models of the drive train. This paper presents simulations of the wind turbine load response to grid faults with an advanced aeroelastic computer code (HAWC2). The core of this code is an advanced model for the flexible structure of the wind...... turbines, taking the flexibility of the tower, blades and other components of the wind turbines into account. The effect of a grid fault on the wind turbine flexible structure is assessed for a typical fixed speed wind turbine, equipped with an induction generator....

  12. Small Wind Energy Systems

    DEFF Research Database (Denmark)

    Simoes, Marcelo; Farret, Felix Alberto; Blaabjerg, Frede

    2015-01-01

    devices, and a centralized distribution control. In order to establish a small wind energy system it is important to observe the following: (i) Attending the energy requirements of the actual or future consumers; (ii) Establishing civil liabilities in case of accidents and financial losses due to shortage...... or low quality of energy; (iii) Negotiating collective conditions to interconnect the microgrid with the public network or with other sources of energy that is independent of wind resources; (iv) Establishing a performance criteria of power quality and reliability to end-users, in order to reduce costs...... and guaranteeing an acceptable energy supply. This paper discuss how performance is affected by local conditions and random nature of the wind, power demand profiles, turbine related factors, and presents the technical issues for implementing a self-excited induction generator system, or a permanent magnet based...

  13. Superconducting Wind Turbine Generators

    DEFF Research Database (Denmark)

    Mijatovic, Nenad

    in this thesis is a part of a larger endeavor, the Superwind project that focused on identifying the potentials that HTS machines could offer to the wind industry and addressing some of the challenges in the process. In order to identify these challenges, I have design and constructed a HTS machine experimental...... still be optimized towards more competitive alternative to conventional machines. Additionally, by constructing the HTS machine setup we went through most of the issues related to the HTS machine design which we managed to address in rather simple manner using everyday materials and therefore proving......A HTS machine could be a way to address some of the technical barriers offshore wind energy is about to face. Due to the superior power density of HTS machines, this technology could become a milestone on which many, including the wind industry, will rely in the future. The work presented...

  14. A simplified model predicting the weight of the load carrying beam in a wind turbine blade

    DEFF Research Database (Denmark)

    Mikkelsen, Lars Pilgaard

    2016-01-01

    Based on a simplified beam model, the loads, stresses and deflections experienced by a wind turbine blade of a given length is estimated. Due to the simplicity of the model used, the model is well suited for work investigating scaling effects of wind turbine blades. Presently, the model is used t...

  15. Stress Management

    Science.gov (United States)

    Healthy Lifestyle Stress management By Mayo Clinic Staff Stress basics Stress is a normal psychological and physical ... of life. Start practicing stress management techniques today. Stress relief The pace and challenges of modern life ...

  16. Childhood Stress

    Science.gov (United States)

    ... Safe Videos for Educators Search English Español Childhood Stress KidsHealth / For Parents / Childhood Stress What's in this ... and feel stress to some degree. Sources of Stress Stress is a function of the demands placed ...

  17. 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...

  18. Strategic wind power trading considering rival wind power production

    DEFF Research Database (Denmark)

    Exizidis, Lazaros; Kazempour, Jalal; Pinson, Pierre

    2016-01-01

    In an electricity market with high share of wind power, it is expected that wind power producers may exercise market power. However, wind producers have to cope with wind’s uncertain nature in order to optimally offer their generation, whereas in a market with more than one wind producers......, uncertainty of rival wind power generation should also be considered. Under this context, this paper addresses the impact of rival wind producers on the offering strategy and profits of a pricemaker wind producer. A stochastic day-ahead market setup is considered, which optimizes the day-ahead schedules...... considering a number of foreseen real-time scenarios. The results indicate that strategic wind producer is more likely to exercise market power having a mid-mean or low-mean forecast distribution, rather than having a high-mean one. Furthermore, it is observed that its offering strategy varies considerably...

  19. Wind Power Today: 2000 Wind Energy Program Highlights

    Energy Technology Data Exchange (ETDEWEB)

    Weis-Taylor, W.

    2001-05-08

    Wind Power Today is an annual publication that provides an overview of the U.S. Department of Energy's Wind Energy Program. The purpose of Wind Power Today is to show how DOE's Wind Energy Program supports wind turbine research and deployment in hopes of furthering the advancement of wind technologies that produce clean, low-cost, reliable energy. Content objectives include: educate readers about the advantages and potential for widespread deployment of wind energy; explain the program's objectives and goals; describe the program's accomplishments in research and application; examine the barriers to widespread deployment; describe the benefits of continued research and development; facilitate technology transfer; and attract cooperative wind energy projects with industry.

  20. 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