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Journal articles on the topic 'Wind quartets'
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1
Barkin, Elaine, Arthur Berger, and Milton Babbitt. "Quartet for Winds." American Music 7, no. 3 (1989): 351. http://dx.doi.org/10.2307/3052090.
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Hwang, Paul A., Yalin Fan, Francisco J. Ocampo-Torres, and Héctor García-Nava. "Ocean Surface Wave Spectra inside Tropical Cyclones." Journal of Physical Oceanography 47, no. 10 (October 2017): 2393–417. http://dx.doi.org/10.1175/jpo-d-17-0066.1.
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AbstractDirectional wave spectra acquired in hurricane reconnaissance missions are compared with wind-wave spectral models. The comparison result is quantified with two indices of model–measurement spectral agreement. In the main region of hurricane coverage, the indices vary sinusoidally with the azimuth angle referenced to the hurricane heading while showing a weak dependence on the radial distance from the hurricane center. The measured spectra agree well with three models evaluated in the back and right quarters, and they are underdeveloped in the front and left quarters. The local wind and wave directions also show a weak radial dependence and sinusoidal variation along the azimuth. The wind and wave vectors are almost collinear in the back and right quarters; they diverge azimuthally and become almost perpendicular in the left quarter. The azimuthally cyclical correlation between the indices of spectral agreement and the wind-wave directional difference is well described by the sinusoidal variations. Also discussed is the wide range of the spectral slopes observed in both hurricane and nonhurricane field data. It is unlikely that the observed spectral slope variation is caused by Doppler frequency shift from background currents. No clear correlation is found between spectral slope and various wind and wave parameters. The result suggests that the spectral slope needs to be treated as a stochastic random variable. Complementing the existing wind-wave spectral models that prescribe a fixed spectral slope of either −4 or −5, a general spectral model with its spectral parameters accommodating a variable spectral slope is introduced.
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Shields, Julia, and Kirsty Murray. "Bridie's Fire, Children of the Wind Quartet, Volume 1." Labour History, no. 89 (2005): 268. http://dx.doi.org/10.2307/27516105.
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Katz, J., and L. Dykstra. "Effect of Passenger Car’s Rear Deck Geometry on Its Aerodynamic Coefficients." Journal of Fluids Engineering 114, no. 2 (June 1, 1992): 186–90. http://dx.doi.org/10.1115/1.2910014.
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The effects of aerodynamic modifications near the rear deck of a passenger-car based race car were investigated experimentally. The modifications were evaluated on a quarter-scale wind tunnel model and included a rear spoiler and a wing. The experimental results indicate that these devices alter the flow field on the vehicle’s body resulting in considerable negative lift coefficients. Also, this aerodynamic interaction is sensitive to rear wing location and when properly placed the total lift owing to the rear wing, combined with its effect on the vehicle’s body, can amount to twice the lift of the isolated wing.
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Vatamaniuk, Nataliia. "DEFINITION OF THE INTRA QUARTER SPACES AND THEIR FUNCTIONS IN THE PLANNING STRUCTURE OF HISTORICAL CITIES." Current problems of architecture and urban planning, no. 58 (November 30, 2020): 48–55. http://dx.doi.org/10.32347/2077-3455.2020.58.48-55.
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The article gives the definition of intra quarter spaces using the example of the historical city of Chernivtsi. The main functions of residential courtyards as elements of the urban planning structure are determined.
To define the concept of «intra quarter space», we can turn to several foreign and domestic researchers, architects, city planners. For example, the theorist and architect A. Gutnov characterized the yard as a clearly fixed, closed space. Courtyards were connected by arches or through passages, forming a complex system of intra quarter spaces, which in some cases penetrated large areas of the city [3].
Architect R. Krier in his works on the morphology of urban space defined the interior spaces of historic quarters as protected from the weather and the environment of the territory, which became the appropriate symbols of the private sphere of life [12].
Summarizing all the above statements, we can give a general definition for «intra quarter spaces», that it is an independent, complex-functional structure that provides communication: the house – the courtyard – urban areas.
Exploring the intra quarters of the city of Chernivtsi, we can identify the following functions of the courtyards:
insulating function, which serves as protection against unplanned intrusion of «strangers» or vehicles into the yard;
household function, which includes meeting the needs of residents of nearby houses;
trade function, is the creation in the volumes of the first floors of various commercial premises;
the function of communication, which plays a socio-psychological role of adaptation of residents to the urban environment;
sanitary and hygienic function, including landscaping, the need for insolation, wind and snow protection of the courtyard, etc.
aesthetic function that provides visual comfort from objects of small architectural forms, landscaping (lawns, flower beds), murals on empty walls, etc.
game function and sports and health function.
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Rosén, Mikael, and Anders Hedenström. "Soaring Flight in the Eleonora's Falcon (Falco eleonorae)." Auk 119, no. 3 (July 1, 2002): 835–40. http://dx.doi.org/10.1093/auk/119.3.835.
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Abstract Eleonora's Falcon (Falco eleonorae) breeds in the Mediterranean region and is highly adapted for catching small birds on passage migration between Eurasia and their African winter quarters, which they feed their young. We studied gliding flight behavior of Eleonora's Falcon at a breeding colony located on a small island southwest of Sardinia, Italy. Gliding and soaring flight performance was measured using an optical range finder and evaluated against flight mechanical theory. The male falcon does the majority of hunting and usually sets off from the colony to hunting areas located at high altitude over the open sea to catch prey. To lower the cost of transport and maximize the energy gain from hunting, we show that the birds use vertical winds for soaring when available. The occurrence of rising air changes with wind direction. At north-northwesterly winds (on-shore), slope lift is available outside the nesting cliffs, and at south-southeasterly winds thermals that form over the island drift out over the sea. Our observations demonstrated the flexibility of flight behavior in relation to the wind situation, and birds thereby make full use of available soaring conditions.
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Ardhuin, Fabrice, T. H. C. Herbers, Kristen P. Watts, Gerbrant Ph van Vledder, R. Jensen, and Hans C. Graber. "Swell and Slanting-Fetch Effects on Wind Wave Growth." Journal of Physical Oceanography 37, no. 4 (April 1, 2007): 908–31. http://dx.doi.org/10.1175/jpo3039.1.
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Abstract Wind-sea generation was observed during two experiments off the coast of North Carolina. One event with offshore winds of 9–11 m s−1 directed 20° from shore normal was observed with eight directional stations recording simultaneously and spanning a fetch from 4 to 83 km. An opposing swell of 1-m height and 10-s period was also present. The wind-sea part of the wave spectrum conforms to established growth curves for significant wave height and peak period, except at inner-shelf stations where a large alongshore wind-sea component was observed. At these short fetches, the mean wave direction θm was observed to change abruptly across the wind-sea spectral peak, from alongshore at lower frequencies to downwind at higher frequencies. Waves from another event with offshore winds of 6–14 m s−1 directed 20°–30° from shore normal were observed with two instrument arrays. A significant amount of low-frequency wave energy was observed to propagate alongshore from the region where the wind was strongest. These measurements are used to assess the performance of some widely used parameterizations in wave models. The modeled transition of θm across the wind-sea spectrum is smoother than that in the observations and is reproduced very differently by different parameterizations, giving insights into the appropriate level of dissipation. Calculations with the full Boltzmann integral of quartet wave–wave interactions reveal that the discrete interaction approximation parameterization for these interactions is reasonably accurate at the peak of the wind sea but overpredicts the directional spread at high frequencies. This error is well compensated by parameterizations of the wind input source term that have a narrow directional distribution. Observations also highlight deficiencies in some parameterizations of wave dissipation processes in mixed swell–wind-sea conditions.
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Katz, J., and R. Largman. "Experimental Study of the Aerodynamic Interaction Between an Enclosed-Wheel Racing-Car and Its Rear Wing." Journal of Fluids Engineering 111, no. 2 (June 1, 1989): 154–59. http://dx.doi.org/10.1115/1.3243616.
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A quarter-scale model of an enclosed wheel racing car was tested using the elevated ground plane wind tunnel technique. To increase the aerodynamic down force, two longitudinal underbody channels were built into the vehicle’s lower surface, and a rear wing was added. The effect of these underbody channels, and of wing angle of attack and position, on the vehicle’s drag and down force was experimentally investigated. Results of the experiments indicate that the flow under the car is affected by the presence of the wheels, and the vehicle without a rear wing generates only a negligible downforce. However, the addition of a rear wing enhanced the flow under the vehicle body, resulting in an increased aerodynamic downforce.
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Hwang, Paul A., and Edward J. Walsh. "Propagation Directions of Ocean Surface Waves inside Tropical Cyclones." Journal of Physical Oceanography 48, no. 7 (July 2018): 1495–511. http://dx.doi.org/10.1175/jpo-d-18-0015.1.
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AbstractSurface wave propagation inside tropical cyclones (TCs) is complicated and multiple wave systems are frequently observed. The directional wave spectra acquired by hurricane hunters are analyzed to quantify its azimuthal and radial variations. Referenced to the hurricane heading, the dominate feature in the front half of the TC coverage area is single wave systems propagating toward left and left-front. Multiple wave systems are generally observed in the back and right quarters outside the radius of maximum wind (RMW). The directional differences and locations of occurrences of multisystem spectra are Gaussian distributed. The directional differences of the secondary and tertiary wave systems from the primary system are centered around 60°–70°. The minor systems are more likely on the left-hand side of the primary system than on the right-hand side by a 3-to-1 ratio. The most likely azimuthal location of multisystem spectra is about 210° counterclockwise from the heading. In the right-front quarter, waves propagate into the advancing wind field and experience extended air–sea exchanges to grow higher and longer; in the left-rear quarter, they propagate away from the advancing wind field and are more likely younger seas. The radial variation of wave propagation is relatively minor except inside the RMW. A model describing the dominant wave propagation direction is presented. The regression statistics between modeled and measured wave directions show consistent agreement in 9 of the 11 datasets available for investigation. Causes for the significantly different statistics of the two remaining datasets include proximity to coast (a landfalling case) and rapid change in the hurricane translation speed or direction.
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Roberts, LS, MV Finnis, and K. Knowles. "Modelling boundary-layer transition on wings operating in ground effect at low Reynolds numbers." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 233, no. 11 (October 25, 2018): 2820–37. http://dx.doi.org/10.1177/0954407018804007.
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The transition-sensitive, three-equation k- kL- ω eddy-viscosity closure model was used for simulations of three-dimensional, single-element and multi-element wing configurations operating in close proximity to the ground. The aim of the study was to understand whether the model correctly simulated the transitional phenomena that occurred in the low Reynolds number operating conditions and whether it offered an improvement over the classical fully turbulent k-ω shear stress transport model. This was accomplished by comparing the simulation results to experiments conducted in a 2.7 m × 1.7 m closed-return, three-quarter-open-jet wind tunnel. The model was capable of capturing the presence of a laminar separation bubble on the wing and predicted sectional forces and surface-flow structures generated by the wings in wind tunnel testing to within 2.5% in downforce and 4.1% in drag for a multi-element wing. It was found, however, that the model produced insufficient turbulent kinetic energy during shear-layer reattachment, predicted turbulent trailing-edge separation prematurely in areas of large adverse pressure gradients, and was found to be very sensitive to inlet turbulence quantities. Despite these deficiencies, the model gave results that were much closer to wind-tunnel tests than those given by the fully turbulent k-ω shear stress transport model, which tended to underestimate downforce. Significant differences between the transitional and fully turbulent models in terms of pressure field, wake thickness and turbulent kinetic energy production were found and highlighted the importance of using transitional models for wings operating at low Reynolds numbers in ground effect. The k- kL- ω model has been shown to be appropriate for the simulation of separation-induced transition on a three-dimensional wing operating in ground effect at low Reynolds number.
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Conway, Paul. "John McCabe CD round-up." Tempo 58, no. 229 (July 2004): 53–54. http://dx.doi.org/10.1017/s0040298204290222.
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JOHN McCABE: Concerto for Piano and Wind Quintet; Musica Notturna; Fauvel's Rondeaux; Postcards for wind quintet. The Fibonacci Sequence. Dutton CDLX 7125.‘Old City New Image’. McCABE: String Trio; String Quartet No. 2. DAVID ELLIS: Trio for violin, viola and cello; String Quartet No. 1. Camerata Ensemble. Campion Cameo 2027.McCABE: Piano Concerto No. 2; Concertante Variations on a theme of Nicholas Maw; Six-Minute Symphony; Sonata on a Motet. Tamami Honma (pno), St Christopher Chamber Orchestra c. Donatas Katkus. Dutton CDLX 7133.‘Tenebrae’. McCABE: Variations; Intermezzi; Sostenuto (Study No. 2); Capriccio (Study No. 1); Aubade (Study No. 4); Tenebrae; Scrunch (Study No. 8); Evening Harmonies (Study No. 7). Tamami Honma (pno). Metier MSV CD92071.
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Rickards, Guy. "MARGARET BROUWER, CHEN YI, SADIE HARRISON, MISATO MOCHIZUKI, ONUTE NARBUTAITE, APPARENZE." Tempo 58, no. 229 (July 2004): 60–66. http://dx.doi.org/10.1017/s0040298204360225.
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MARGARET BROUWER: Lament for violin, clarinet, bassoon and percussion12,4,6,10; Light for soprano, harpsichord, flute, clarinet, violin, cello and percussion1,7,2,5,13,14,11; Under the Summertree for piano8; Skyriding for flute, violin, cello & piano3,13,14,9; Demeter Prelude for string quartet15. 1Sandra Simon (sop), 2Sean Gabriel (fl), 3Alice Kogan Weinreb (fl), 4Jean Kopperud (cl), 5Amitai Vardi (cl), 6Donald McGeen (bsn), 7Jeanette Sorrell (hpschd), 8Kathryn Brown (pno), 9Mitsuko Morikawa (pno), 10Dominic Donato (perc), 11Scott Christian (perc), 12Laura Frautschi (vln), 13Gabriel Bolkosky (vln), 14Ida Mercer (vlc), 15Cavani String Quartet. New World 80606-2.CHEN YI: Momentum; Chinese Folk Dance Suite for violin and orchestra1; Dunhuang Fantasy for organ and chamber wind ensemble3; Romance and Dance for 2 violins and string orchestra1,2; Tu. 1Cho-Liang Lin (vln), 2Yi-Jia Susanne Hou (vln), 3Kimberley Marshall (org), Singapore SO c. Lan Shui. BIS-CD-1352.SADIE HARRISON: The Light Garden for mixed quintet1; The Fourteenth Terrace for clarinet and ensemble2; Bavad Khair Baqi! for solo violin3. Traditional Afghan Music4. 1Tate Ensemble, 2Andrew Spalding (cl), Lontano c. Odaline de la Martinez, 3Peter Sheppard Skærved (vln), 4Ensemble Bakhtar. Metier MSV CD92084.MISATO MOCHIZUKI: Si bleu, si calme1; All that is including me for bass flute, clarinet and violin1,2,3; Chimera; Intermezzi I for flute & piano1,4; La chamber claire. 1Eva Furrer (fl, bass fl), 2Bernhard Zachhuber (cl), 3Sophie Schafleitner (vln), 4Marino Formenti (pno), Klangforum Wien c. Johannes Kalitzke. Kairos 0012402KAIONUTE NARBUTAITE: Symphony No. 2; Liberatio for 12 winds, cymbals & 4 strings; Metabole for chamber orchestra. Lithuanian National SO c.Robertas Fervenikas. Finlandia 0927-49597-2.ALLA PAVLOVA: Symphony No. 1, Farewell Russia1,3,4; Symphony No.32,3,5. 1Leonid Lebedev (fl), Nikolay Lotakov (picc), Mikhail Shestakov (vln), Valery Brill (vlc), Mikhail Adamovich (pno); 2Olga Verdernikova (vln), 3Russian PO c. 4Konstantin D. Krimets, 5Alexander Vedernikov. Naxos 8.557157.‘APPARENZE: Collana di Nuove Musiche 1997’. Works by SILVIA DELITALA, RITA PORTERA, CATERINA DE CARLO, BEATRICE CAMPODONICO, PAOLA CIAR-LANTINI, JANET MAGUIRE, MARCO SANTAM BROGIO, PAOLO MINETTI, FEDERICO MONTAGNER, RINALDO BELLUCCI and BIAGIO PUTIGNANO. Maria Vittoria Vallese (sop), Pia Zanca, Fiametta Facchini, Rinaldo Bellucci (pnos), Duo Soncini-Flückiger, Italian Guitar Quartet, Ensemble Paul Klee, Fabrizio Fantini, Gianluca Calonghi (cls), Giuseppe Giannotti (ob). Radio Onda d'Urto E.F.B 001.
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Ali, Nesar, Mostafizur Rahman Komol, and Mohammad Takiuddin Saki. "Study on Thin Airfoil Theory & Performance Test of Elliptical Wing as Compared to Model Mosquito Wing and NACA 64A012 Mod Airfoil." European Journal of Engineering Research and Science 3, no. 4 (April 28, 2018): 48. http://dx.doi.org/10.24018/ejers.2018.3.4.665.
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Thin airfoil theory is a simple conception of airfoils that describes angle of attack to lift for incompressible, inviscid flows. It was first devised by famous German-American mathematician Max Munk and therewithal refined by British aerodynamicist Hermann Glauertand others in the 1920s. The thin airfoil theory idealizes that the flow around an airfoil as two-dimensional flow around a thin airfoil. It can be conceived as addressing an airfoil of zero thickness and infinite wingspan. Thin airfoil theory was particularly citable in its day because it provided a well-established theoretical basis for the following important prominence of airfoils in two-dimensional flow like i) on a symmetric shape of airfoil which center of pressure and aerodynamic center remain exactly one quarter of the chord behind the leading edge, ii) on a cambered airfoil, the aerodynamic center lies exactly one quarter of the chord behind the leading edge and iii)the slope of the lift coefficient versus angle of attack line is two pi ( ) units per radian. The fundamental equation of Prandtl’s lifting-line theory; simply states that the geometric angle of attack is equal to the sum of the effective angle plus the induced angle of attack. And also omitted the theory of elliptical wing theory which indicates that the Elliptical wing has better flight performance than any other airfoil. In this experiment we made a model of elliptical wing and test in wind tunnel to get experimental value. We also analyze the model in simulation software for further knowledge. Comparing this practical and experimental value to other airfoil like Mosquito wing and NACA 64A012 airfoil for further research.
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Gibson, Greg, Matthew Wemple, and Sylvie van Helden. "Potential Variance Affecting Homeotic Ultrabithorax and Antennapedia Phenotypes in Drosophila melanogaster." Genetics 151, no. 3 (March 1, 1999): 1081–91. http://dx.doi.org/10.1093/genetics/151.3.1081.
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Abstract Introgression of homeotic mutations into wild-type genetic backgrounds results in a wide variety of phenotypes and implies that major effect modifiers of extreme phenotypes are not uncommon in natural populations of Drosophila. A composite interval mapping procedure was used to demonstrate that one major effect locus accounts for three-quarters of the variance for haltere to wing margin transformation in Ultrabithorax flies, yet has no obvious effect on wild-type development. Several other genetic backgrounds result in enlargement of the haltere significantly beyond the normal range of haploinsufficient phenotypes, suggesting genetic variation in cofactors that mediate homeotic protein function. Introgression of Antennapedia produces lines with heritable phenotypes ranging from almost complete suppression to perfect antennal leg formation, as well as transformations that are restricted to either the distal or proximal portion of the appendage. It is argued that the existence of “potential” variance, which is genetic variation whose effects are not observable in wild-type individuals, is a prerequisite for the uncoupling of genetic from phenotypic divergence.
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Hwang, Paul A. "Transports and Net Fluxes of Surface Wave Energy and Momentum inside Tropical Cyclones: Spectrum Computation and Modeling." Journal of Physical Oceanography 50, no. 11 (November 2020): 3309–29. http://dx.doi.org/10.1175/jpo-d-20-0104.1.
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AbstractTransports and net fluxes of surface wave energy and momentum inside tropical cyclones (TCs) are analyzed with wave spectra acquired by hurricane hunters. Previous analyses of dominant wave properties show a primary feature of sinusoidal azimuthal variation. Transports calculated from directional wave spectra are also primarily sinusoidal, which is modeled as a harmonic series. The result reveals that forward transport peaks are in the right-front quarter relative to the TC heading, and somewhat weaker valleys of backward transports are in the left-back quarter. Rightward transport peaks are in the right-back quarter and stronger leftward transport valleys are in the left-front quarter. Net fluxes are derived analytically from the gradients of transports. Their azimuthal variations are primarily biharmonic with forward trend confined in a slightly left-tilted parallel channel about a width two to three radius of maximum wind (RMW) on each side of the TC center. Leftward net fluxes are in a parallel channel of similar size and normal to that of the forward net fluxes. In vectors, the right-back quarter is a region of net influxes of energy and momentum. The TC central region has strong local fluxes that lead to bifurcation of the flux lines into leftward and forward paths. This may play a role in stabilizing the TC propagation. The net fluxes are a small fraction of the expected energy and momentum inputs from local wind except near the eye region. Within about 30 km from the TC center the local wind speed may exceed 30 m s−1 and the net fluxes can exceed 50% of the expected local wind input.
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Ortiz, Miguel Mejías, Roger Eritja, José Antonio Oteo, and Ignacio Ruiz-Arrondo. "Description of a Culex pipiens Gynandromorph Captured in La Rioja (Spain)." Journal of the American Mosquito Control Association 35, no. 4 (December 1, 2019): 288–90. http://dx.doi.org/10.2987/19-6857.1.
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ABSTRACT A gynandromorph is an imago combining well-defined male and female structures, caused by different processes, and it is infrequent in wild-caught mosquitoes. A Culex pipiens gynandromorph was caught in La Grajera wetland (La Rioja, Spain) in 2016. The phenotypic sex of wings was determined using linear discriminating analysis and the training error for the model on a previous database of sex-classified wing biometry data. It is suggested that the individual had an uncommon layout categorized as a top quarter male gynandromorph.
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Korotenko, K. A., A. V. Sentchev, and F. G. Schmitt. "Effect of variable winds on current structure and Reynolds stresses in a tidal flow: analysis of experimental data in the eastern English Channel." Ocean Science 8, no. 6 (November 27, 2012): 1025–40. http://dx.doi.org/10.5194/os-8-1025-2012.
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Abstract. 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 southwesterly winds while, during the flood, the surface stresses slightly exceeded those estimated for a calm period. A comparison of obtained results gives a good agreement with those of other researchers working on direct measurements of turbulence in tidal flows.
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Korotenko, K. A., A. V. Sentchev, and F. G. Schmitt. "Effect of variable winds on current structure and Reynolds stresses in a tidal flow: analysis of experimental data in the Eastern English Channel." Ocean Science Discussions 9, no. 3 (June 13, 2012): 2215–54. http://dx.doi.org/10.5194/osd-9-2215-2012.
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Abstract. 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 20-m 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 magnitude reached 15 m s−1 and wave height reached 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 upper 10-m 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, with 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 W m−3 and 0.5 m2 s−1, respectively, during the flood flow. Over the storm periods, we found the highest stress values (~−2 Pa) during ebb when tidal currents were opposite to the southwesterly winds while, during the flood, the surface stresses slightly exceeded those estimated for a calm period.
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Mailyan, B., C. Munteanu, and S. Haaland. "What is the best method to calculate the solar wind propagation delay?" Annales Geophysicae 26, no. 8 (August 5, 2008): 2383–94. http://dx.doi.org/10.5194/angeo-26-2383-2008.
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Abstract. We present a statistical study of propagation times of solar wind discontinuities between Advanced Composition Explorer (ACE) spacecraft orbiting the L1 libration point and the Cluster quartet of spacecraft near the Earth's magnetopause. The propagation times for almost 200 events are compared with the predicted times from four different models. The simplest model assumes a constant convective motion of solar wind disturbances along the Sun-Earth line, whereas more sophisticated models take the orientation of the discontinuity as well as the real positions of the solar wind monitor and target into account. The results show that taking orientation and real position of the solar wind monitor and target into account gives a more precise time delay estimation in most cases. In particular, we show that recent modifications to the minimum variance technique can improve the estimation of propagation times of solar wind discontinuities.
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Hubova, Olga, and Lenka Konecna. "The Influence of the Wind Flow Around the Free Ends of High-Rise Building on the Values of External Wind Pressure Coefficients." Applied Mechanics and Materials 837 (June 2016): 203–8. http://dx.doi.org/10.4028/www.scientific.net/amm.837.203.
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The external wind pressure coefficients are based on the measurements on the structures without free-end flow near the top of vertical structures. The end-effect factor takes into account reduction of the pressures due to specific flow around the top of atypical building. The article is based on the experimental measurements in BLWT tunnel in Bratislava on the model of building with cross section of the quarter circle. The model was tested in two spaces - in steady and turbulent wind flow, by changing of wind direction and wind velocity. The end-effect factor depending on the wind direction is shown in the graphs.
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Lu, Jun, Chun Die Li, Liang Wang, Yu Lu Chen, and Xin Hui Zhang. "Analyzing the Factors and Variables of Heat Island Effect in Comprehensive High-Rise Residential Quarter of Mountain City." Advanced Materials Research 356-360 (October 2011): 980–85. http://dx.doi.org/10.4028/www.scientific.net/amr.356-360.980.
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In order to guide the planning of urban microclimate, the influencing variables of the heat island intensity (UII) of tall residential quarter in mountain city in spring and summer is quantitatively analyzed. Through experiments and simulations, 6 variables including wind speed(WS), green ratio(GR), impervious ratio(IR), average surface temperature(AST) , shadow ratio(SR), H / W were chosen and summarized as factors by dimension reduction in factors analysis; further, the dominant variables and factors in different time were confirmed through multiple linear regression analysis of the factors/ variables and UII. Results revealed that in the microclimate tests, it is appropriate to make factor analysis when the cumulative contribution rate of a factor is higher than 50%, and the significant correlated factor of UII is horizontal surface factor (HSF) in three fifths of the testing time in July. The variable analysis revealed that the significance of WS on UII is more in cloudy days than that in sunny days; the significance of SR is higher in summer than that in transition seasons and is most in 15:00, it demonstrates that optimal utilization of the building shadings is an effective way to improve the outdoor thermal environment in residential quarters.
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Jiang, Xin Bo, Chang Zhi Yang, Biao Tang, and Wei Chen. "Coupled Simulation and Analysis of Wind Environment around Residential Quarter in Hot Summer and Cold Winter Area in China." Advanced Materials Research 726-731 (August 2013): 3627–32. http://dx.doi.org/10.4028/www.scientific.net/amr.726-731.3627.
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Computer aided design is an effective means of wind environment assessment and prediction under complex layout, In this paper, the relationships of contact and containment among wind environment was studied by coupled simulation and analysis of wind environment around residential quarter in hot summer and cold winter area, and analyzed how to fix the layout of indoor and outdoor by simulation software during the operation, and make them reach the requirement of Evaluation standard for green building, at the same time make the ecological effects of the buildings complex to maximize.
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Tryhuba, Anatoliy, Oleg Bashynsky, Ihor Garasymchuk, Oleg Gorbovy, Dariia Vilchinska, and Viktor Dubik. "Research of the variable natural potential of the wind and energy energy in the northern strip of the ukrainian carpathians." E3S Web of Conferences 154 (2020): 06002. http://dx.doi.org/10.1051/e3sconf/202015406002.
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The expediency of studying the varying potential of wind and solar energy in the northern strip of the Ukrainian Carpathians is substantiated. The technique of conducting experiments to determine the natural potential of wind and solar energy is proposed and a model for determining the relative volumes of electricity generation by wind farms and solar electrical installations is developed. Based on the conducted research, according to the Drohobych meteorological station, an energy assessment of wind and solar energy resources in the northern strip of the Ukrainian Carpathians was performed. It is substantiated that the theoretical curves of distribution of wind velocity in separate quarters of the year in the territory of the northern strip of the Ukrainian Carpathians are described by the Weibull distributions. Based on the calculations, it is established that the highest total daily solar radiation is in the summer months. Daily graphs of the relative generation of electricity by wind farms and solar electric installations have been constructed. The expediency of formation of combined systems of energy supply of objects from wind and solar energy in the northern strip of the Ukrainian Carpathians has been established. The substantiated patterns of change in the natural potential of wind and solar energy, as well as the graphs of the relative generation of electricity from them, will significantly speed up managerial decisions and improve their quality.
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Adlerman, Edwin J., and Kelvin K. Droegemeier. "The Dependence of Numerically Simulated Cyclic Mesocyclogenesis upon Environmental Vertical Wind Shear." Monthly Weather Review 133, no. 12 (December 1, 2005): 3595–623. http://dx.doi.org/10.1175/mwr3039.1.
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Abstract Building upon the authors’ previous work that examined the dynamics of numerically simulated cyclic mesocyclogenesis and its dependence upon model physical and computational parameters, this study likewise uses idealized numerical simulations to investigate associated dependencies upon ambient vertical wind shear. Specifically, the authors examine variations in hodograph shape, shear magnitude, and shear distribution, leading to storms with behavior ranging from steady state to varying degrees of aperiodic occluding cyclic mesocyclogenesis. However, the authors also demonstrate that a different mode of nonoccluding cyclic mesocyclogenesis may occur in certain environments. Straight hodographs (unidirectional shear) produce only nonoccluding cyclic mesocyclogenesis. Introducing some curvature by adding a quarter circle of turning at low levels results in steady, nonoccluding, and occluding modes. When a higher degree of curvature is introduced—for example, turning through half and three-quarter circles—the tendency for nonoccluding behavior is diminished. None of the full-circle hodographs exhibited cycling during 4 h of simulation. Overall, within a given storm, the preferred mode of cycling is related principally to hodograph shape and magnitude of the ambient vertical shear.
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Huang, Yong Yu, Qiu Yun Mo, Xu Zhang, and Zu Peng Zhou. "Numerical Simulations of Spherical Vertical-Axis Wind Rotor." Applied Mechanics and Materials 291-294 (February 2013): 456–60. http://dx.doi.org/10.4028/www.scientific.net/amm.291-294.456.
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In this paper, the effects of the shape of three types of the blade on power coefficient of Savonius rotors are studied by simulating the model using numerical simulation under the same conditions. For this purpose, three spherical rotors with different configurations but identical number of stages and blades, aspect ratio and overlap keeping the identical projected area of each rotor are constructed. The geometries of blade of the three rotors are a plane, a semi-circle and a quarter of sphere. The building data are calculated on the basis of the nominal wind velocity V= 10m/s and the speed ratio λ= 0.3 with an industrial flow simulation code (ANSYS-Fluent). The result shows that the rotor with semicircular blades has a higher value of power coefficient in comparison with other rotors.
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Braithwaite, Roger J., and Ole B. Olesen. "Response of the Energy Balance on the Margin of the Greenland Ice Sheet to Temperature Changes." Journal of Glaciology 36, no. 123 (1990): 217–21. http://dx.doi.org/10.1017/s0022143000009461.
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AbstractDaily ice ablation on two outlet glaciers from the Greenland ice sheet, Nordbogletscher (1979–83) and Qamanârssûp sermia (1980–86), is related to air temperature by a linear regression equation. Analysis of this ablation-temperature equation with the help of a simple energy-balance model shows that sensible-heat flux has the greatest temperature response and accounts for about one-half of the temperature response of ablation. Net radiation accounts for about one-quarter of the temperature response of ablation, and latent-heat flux and errors account for the remainder. The temperature response of sensible-heat flux at QQamanârssûp sermia is greater than at Nordbogletscher mainly due to higher average wind speeds. The association of high winds with high temperatures during Föhn events further increases sensible-heat flux. The energy-balance model shows that ablation from a snow surface is only about half that from an ice surface at the same air temperature.
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Braithwaite, Roger J., and Ole B. Olesen. "Response of the Energy Balance on the Margin of the Greenland Ice Sheet to Temperature Changes." Journal of Glaciology 36, no. 123 (1990): 217–21. http://dx.doi.org/10.3189/s0022143000009461.
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AbstractDaily ice ablation on two outlet glaciers from the Greenland ice sheet, Nordbogletscher (1979–83) and Qamanârssûp sermia (1980–86), is related to air temperature by a linear regression equation. Analysis of this ablation-temperature equation with the help of a simple energy-balance model shows that sensible-heat flux has the greatest temperature response and accounts for about one-half of the temperature response of ablation. Net radiation accounts for about one-quarter of the temperature response of ablation, and latent-heat flux and errors account for the remainder. The temperature response of sensible-heat flux at QQamanârssûp sermia is greater than at Nordbogletscher mainly due to higher average wind speeds. The association of high winds with high temperatures during Föhn events further increases sensible-heat flux. The energy-balance model shows that ablation from a snow surface is only about half that from an ice surface at the same air temperature.
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Schahinger, RB. "Structure of coastal upwelling events observed off the south-east coast of South Australia during February 1983 - April 1984." Marine and Freshwater Research 38, no. 4 (1987): 439. http://dx.doi.org/10.1071/mf9870439.
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Observations of upwelling along the south-east coast of South Australia during the summers of 1983 and 1984 are presented. In situ measurements were obtained from a number of current meters moored across the continental shelf near 37.5�S.,139.5�E. These were complemented by wind and sea level measurements along the coast and also monthly hydrographic surveys. Differences between summer and winter regimes are discussed in both physical and dynamical terms. The summer weather pattern gives rise to winds which are favourable to upwelling along this coast more than 50% of the time (i.e. winds from the south-east quarter). The evolution of two upwelling events and the associated shelf circulation are documented. Salient features include the offshore transport of water in a shallow surface layer 0 (20 m) in response to south-easterly winds; an onshore compensatory flow occurs almost immediately below. The summer thermocline shoals soon after the onset of winds favouring upwelling, leading to pronounced cross-shelf surface-temperature gradients with cooler (upwelled) water at the surface near the coast. The surfaced thermocline moves offshore and attains an equilibrium position in the vicinity of the shelf edge (after 4-5 days), as shown by infrared satellite images, while water from depths of 250-300 m encroaches onto the shelf. Alongshore currents reach speeds of more than 50 cm s-1 in the outer-shelf region and are strongly influenced by the position of the upwelling front. Brief comparisons are drawn with other upwelling regions.
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Kupka, I. "Growth reaction of young wild cherry (Prunus aviumL.) trees to pruning." Journal of Forest Science 53, No. 12 (January 7, 2008): 555–60. http://dx.doi.org/10.17221/2165-jfs.
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A large crown is one of the most important prerequisites for the good growth of a tree and therefore the crown could be called an engine of increment. The care for a large crown brings a decrease in the bole value at the same time as it makes large branches and later knots on it. Pruning is a possible solution of these two contradictions. Young wild cherry trees were pruned in three different ways: (<I>i</I>) half of the crown left, (<I>ii</I>) one quarter of the crown left and (<I>iii</I>) control, i.e. no pruning. The results show that height growth was not influenced by pruning while diameter growth was significantly affected. The crown reduction to a half means 10% less in diameter growth within a 5-year period after pruning. The crown reduction to one quarter of the crown means only two thirds of ‘full’ diameter growth on the control plot. The data suggest that the pruning of young wild cherry trees should be done moderately (more than a half of the crown should be left) and pruning should be done when the bottom part of the crown is in the shadow zone of the crown layer, not earlier.
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Sohoni, Vaishali, Shivcharan Gupta, and R. K. Nema. "Design of wind-PV based hybrid standalone energy systems for three sites in central India." ECTI Transactions on Electrical Engineering, Electronics, and Communications 17, no. 1 (September 9, 2019): 24–34. http://dx.doi.org/10.37936/ecti-eec.2019171.215397.
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The aim of this study is to design renewable energy based hybrid standalone systems to supply two rural and one urban sites of Madhya Pradesh state in India. These locations characterize different load profiles and wind and solar resources. The wind speed data measured at these sites and solar radiation data obtained from NASA are utilized to carry out theanalyses of these systems using HOMER Pro. These systems are designed to cater for domestic electricity demand of one rural site, domestic and agricultural demand of another rural site and residential load demand of staff quarters of an urban institution. The pattern of power consumption of the loads considered for these sites is suitably modelled and different combinations of hybrid systems are simulated to identify the optimal system based on least life cycle cost. Results show that the most economically feasible system to supply the load demand of the three sites is comprised of different combinations of renewable energy sources viz. only wind, wind- solar and only solar based systems. Each design also includes diesel generator back up and battery storage to ensure reliability of power supply and a converter to maintain the energy flow between ac and dc components.
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Clarke, Allan J. "Analytical Theory for the Quasi-Steady and Low-Frequency Equatorial Ocean Response to Wind Forcing: The “Tilt” and “Warm Water Volume” Modes." Journal of Physical Oceanography 40, no. 1 (January 1, 2010): 121–37. http://dx.doi.org/10.1175/2009jpo4263.1.
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Abstract Analytical theory is used to examine the linear response of a meridionally unbounded stratified ocean to large-scale, low-frequency wind forcing. The following results, applied mainly to the equatorial Pacific, were obtained. (i) Provided that the wind stress curl vanishes at large distance from the equator, a general Sverdrup solution is valid in the quasi-steady (frequency ω → 0) limit. The meridionally averaged zonal flow toward the western boundary layer is zero so that there is no net mass flow into the boundary layer and the large-scale boundary condition is therefore satisfied. This solution predicts a zero pycnocline response in the eastern equatorial Pacific. It therefore predicts that, for the eastern equatorial Pacific, a slow weakening of the equatorial trade winds will not lead to long-term El Niño conditions there. (ii) Consistent with observations and other previous work, for finite but small frequencies there are two modes of equatorial motion. One is a “tilt” mode in which the equatorial sea level and thermocline are tilted by the in-phase zonal wind stress and the other is an equatorial warm water volume (WWV) mode in which the discharge of equatorial warm water (negative WWV anomaly) lags the wind stress forcing by a quarter of a period. (iii) The amplitude of the WWV mode approaches zero like ω1/2. Therefore, as ω → 0, the equatorial solution reduces to the tilt mode. (iv) The WWV mode is not due to a dominant meridional divergence driven by the wind, as suggested by some previous work. Meridional and zonal divergence approximately cancel. Reflection of energy at both ocean boundaries together with the strong dependence of long Rossby wave speed on latitude is crucial to the existence of the disequilibrium WWV mode. Because higher-latitude Rossby waves travel so much more slowly, the Rossby waves reflecting from the western ocean boundary are not in phase. This gives rise to a reflected equatorial Kelvin wave and a WWV that is not in phase with the wind stress forcing. (v) Observations from past work have shown that much low-frequency wave energy, particularly westward propagating Rossby wave energy poleward of about 5°N and 5°S, is damped out before it reaches the western ocean boundary. In this way dissipation likely has a strong influence on the equatorial Kelvin wave reflection and hence the disequilibrium WWV.
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Darwish, Abdul Salam, and Riadh Al-Dabbagh. "Wind energy state of the art: present and future technology advancements." Renewable Energy and Environmental Sustainability 5 (2020): 7. http://dx.doi.org/10.1051/rees/2020003.
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Renewables today are the first-choice option for a modern power system. Wind and solar are now competitive with conventional sources and commanded a high percentage of investments in renewable power. The cost of wind turbines has fallen by nearly 1/3rd since 2009 and that of solar photovoltaic (PV) modules by 80%. The number of countries that held auctions to deploy renewables has increased (from 6 in 2005 to 67 countries in 2017) with a very large increase in global investment. Global cumulative installed wind power capacity had more than 645 GW by the first quarter of 2019. The paper reviews the recent developments in wind energy conversion systems technology and discusses future expectations. Offshore wind turbines are the most possible technology for future utilization and of this, floating wind turbines are to dominate with larger scales could reach three times the present introduced scales. This is to provide more than 20% of the global demand in 2030. The paper presents several case studies for each case and highlights the technological aspects that support each development. The most important design advancements are also discussed with a forecast of the future design expectation that will affect the wind power generation program.
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Hu, Huan Ran, and Guan Xin Hong. "Simulation Method for 3-D Wind Field over Complex Terrain with Asymmetrical Mountains." Applied Mechanics and Materials 444-445 (October 2013): 549–54. http://dx.doi.org/10.4028/www.scientific.net/amm.444-445.549.
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It is important for the research of flight characteristics to master the distribution of wind field and the character of turbulence intensity in a complex-terrain mountain. Based on the potential flow theories in fluid dynamics, a numerical simulation method of complex terrain including asymmetrical and symmetrical mountains has been developed in this paper. In particular, asymmetrical mountains are simulated by the combination of two transformed quarter-semiellipsoids. Furthermore, mountain-induced airflow is calculated based on potential flow theory, which could reflect the characteristic of wind field. As an example, the wind field near Dingling airport in Beijing has been simulated and analyzed by this method. The results demonstrate that this method is suitable and accurate for engineering practice, and also applicable for flight dynamics characteristics analysis of aircrafts.
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Jumper, E. J., R. L. Dimmick, and A. J. S. Allaire. "The Effect of Pitch Location on Dynamic Stall." Journal of Fluids Engineering 111, no. 3 (September 1, 1989): 256–62. http://dx.doi.org/10.1115/1.3243639.
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This paper reports the results of theoretical and wind-tunnel studies of the effect of pitch location on dynamic stall for an airfoil pitching at constant rate. A modified momentum-integral method was used to predict the effect of pitch location and rate on the delay in quarter-chord separation. The wind-tunnel study involved the collection of time-varying pressure readings from 16 locations on an NACA 0015 airfoil that were subsequently used to determine lift, pressure-drag, and moment coefficients as functions of angle of attack for 140 test cases, covering 28 dynamic airspeed/pitch-rate/pitch-location combinations. Dynamic-stall effects of change (from steady flow) in the angle of attack at which separation occurs at the quarter chord (for comparison with the momentum-integral results), and change in the angle of attack at which stall occurs were extracted from these data and found to collapse best onto a non-dimensional pitch rate given by the chord times the pitch rate divided by two times the free-stream velocity. An adjusted non-dimensional rate formed by replacing one half the chord with the fraction of the chord corresponding to the pitch location was also examined and found not to be the proper non-dimensional variable for collapsing the data. The quarter-chord separation data compared favorably with the theoretical predictions.
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Lohani, Sunil Prasad, and Andrew Blakers. "100% renewable energy with pumped-hydro-energy storage in Nepal." Clean Energy 5, no. 2 (May 13, 2021): 243–53. http://dx.doi.org/10.1093/ce/zkab011.
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Abstract A radical transformation of the global energy system is underway. Solar photovoltaics and wind now comprise three-quarters of the global net new electricity-generation-capacity additions because they are cheap. The deep renewable electrification of energy services including transport, heating and industry will allow solar and wind to largely eliminate fossil fuels over the next few decades. This paper demonstrates that Nepal will be able to achieve energy self-sufficiency during the twenty-first century. Nepal has good solar and moderate hydroelectric potential but has negligible wind- and fossil-energy resources. The solar potential is about 100 times larger than that required to support a 100% solar-energy system in which all Nepalese citizens enjoy a similar per-person energy consumption to developed countries, without the use of fossil fuels and without the environmental degradation resulting from damming Nepal’s Himalayan rivers. Nepal has vast low-cost off-river pumped hydro-energy-storage potential, thus eliminating the need for on-river hydro storage and moderating the need for large-scale batteries. Solar, with support from hydro and battery storage, is likely to be the primary route for renewable electrification and rapid growth of the Nepalese energy system.
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Tang, Zheng, Wei Feng, Mengfan Wang, Benli Yu, and Guojie Tu. "Research on technology of 1550nm all-fiber continuous wave coherent Doppler wind lidar." E3S Web of Conferences 261 (2021): 01038. http://dx.doi.org/10.1051/e3sconf/202126101038.
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In order to obtain the telemetry data of wind field 80 m ahead of the wind turbine, an all-fiber continuous wave coherent Doppler lidar (CW-CDL) system is demonstrated in this paper. The CW-CDL of all-fiber structure has advantages of the compact structure, good stability and low cost. However, there is inherent crosstalk in the optical circulator of the optical fiber module, the crosstalk light and the reference light enter the photon detector together to produce phase induced intensity noise (PIIN). Aiming to effectively solve the noise, we proposed a polarization control method by combining a polarization beam splitter and a quarter wave plate to reduce the PIIN in the system. The wind speed Doppler signal at 80 meters is obtained on a sunny day, and the typical signal-to-noise ratio can reach 21.7 dB.
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Guerrero, Bridget L., Stephen H. Amosson, Thomas H. Marek, and Jeffrey W. Johnson. "Economic Evaluation of Wind Energy as an Alternative to Natural Gas Powered Irrigation." Journal of Agricultural and Applied Economics 42, no. 2 (May 2010): 277–87. http://dx.doi.org/10.1017/s107407080000345x.
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High natural gas prices have agricultural producers searching for alternative energy sources for irrigation. The economic feasibility of electric and hybrid (electric/wind) systems are evaluated as alternatives to natural gas powered irrigation. Texas Panhandle and Southern Kansas farms are assessed with a quarter-mile sprinkler system, three crops, and two pumping lifts. Breakeven points identify the price at which conversion from a natural gas irrigation system to an electric or hybrid system is cost effective. Results indicate electricity is a more feasible energy source for irrigation and policy changes such as net metering are necessary to make hybrid systems viable.
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Nigatie, Dereje Bishaw, Megersa O. Dinka, and Tilahun Hordofa. "Effects of Operating Pressure, Nozzle Diameter and Wind Speed on the Performance of Sprinkler in Irrigation System during Water Application." ABC Journal of Advanced Research 7, no. 2 (December 31, 2018): 45–56. http://dx.doi.org/10.18034/abcjar.v7i2.78.
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Owing to an increasing demand for irrigation water associated with the massive expansion of irrigated sugarcane farms in Ethiopia, there is a need to use the available water efficiently and effectively. Accordingly, a study was conducted to evaluate the effect of operating pressure and nozzle size on the field performance of dragline sprinkler system at Wonji/Shoa Sugar Estate. The study was conducted under three wind phases (morning, mid-day and late afternoon) using three operating pressures (250 kPa, 300 kPa and 350 kPa) and two nozzle sizes (4.4 and 4.8 mm). Uniformity measurements were performed using single sprinkler and four sprinklers configurations. An application efficiency of low-quarter of 41% to 80.3% and actual application efficiency of low-quarter of 30.1% to 37.5% were achieved under the respective test combinations. Christiansen’s coefficient of uniformity of 71.7% to 86.3%, and distribution uniformity of 61% to 80.3% were achieved under different test combinations for four sprinklers test. The achievable delivery performance ratio was in the range of 0.81 to 1.18. The experimental results illustrated that, lower operating pressure and higher wind velocity were the major factors responsible for the low water distribution uniformity and efficiency.
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MacDonald, M. K., J. W. Pomeroy, and A. Pietroniro. "Hydrological response unit-based blowing snow modelling over an alpine ridge." Hydrology and Earth System Sciences Discussions 7, no. 1 (February 12, 2010): 1167–208. http://dx.doi.org/10.5194/hessd-7-1167-2010.
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Abstract. Snow redistribution by wind and the resulting accumulation regimes were simulated for two winters over an alpine ridge transect located in the Canada Rocky Mountains. Simulations were performed using physically based blowing snow and snowmelt models. A hydrological response unit (HRU)-based spatial discretization was used rather than a more computationally expensive fully-distributed one. The HRUs were set up to follow an aerodynamic sequence, whereby eroded snow was transported from windswept, upwind HRUs to drift accumulating, downwind HRUs. HRUs were selected by examining snow accumulation patterns from manual snow depth measurements. Simulations were performed using two sets of wind speed forcing: (1) station observed wind speed, and (2) modelled wind speed from a widely applied empirical, terrain-based windflow model. Best results were obtained when using the site meteorological station wind speed data. The windflow model performed poorly when comparing the magnitude of modelled and observed wind speeds, though over-winter snow accumulation results obtained when using the modelled wind speeds were reasonable. However, there was a notable discrepancy (17%) between blowing snow sublimation quantities estimated when using the modelled and observed wind speeds. As a result, the end-of-winter snow accumulation was considerably underestimated (32%) when using the modelled wind speeds. That snow redistribution by wind can be adequately simulated in computationally efficient HRUs over this alpine ridge has important implications for representing snow transport in large-scale hydrology models and land surface schemes. Snow redistribution by wind was shown to significantly impact snow accumulation regimes in mountainous environments as snow accumulation was reduced to less than one-third of snowfall on windswept landscapes and nearly doubled in certain lee slope and treeline areas. Blowing snow sublimation losses were shown to be significant (approximately one-quarter of snowfall or greater).
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Hwang, Paul A. "Fetch- and Duration-Limited Nature of Surface Wave Growth inside Tropical Cyclones: With Applications to Air–Sea Exchange and Remote Sensing." Journal of Physical Oceanography 46, no. 1 (January 2016): 41–56. http://dx.doi.org/10.1175/jpo-d-15-0173.1.
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AbstractThe 2D wavenumber spectra collected by an airborne scanning radar altimeter in hurricane hunter missions are used to investigate the fetch- and duration-limited nature of wave growth inside hurricanes. Despite the much more complex wind-forcing conditions, the dimensionless growth curves obtained with the wind-wave triplets (reference wind velocity, significant wave height, and dominant wave period) inside hurricanes, except near the eye region, are comparable to the reference similarity counterparts constructed with the wind-wave triplets collected in field experiments conducted under ideal quasi-steady fetch-limited conditions. In dimensionless terms, the youngest waves are in the back quarter of the hurricane. In the Northern Hemisphere, the dimensionless frequency decreases systematically counterclockwise (CCW), and the most mature waves are in the left-hand sector. Except for those waves near the eye region, the dominant wave phase speeds are about 0.32 to 0.71 times of the local wind speed, and they are proper wind seas. Based on the computation of the wind input or energy dissipation in the wave field, a conservative estimate of the air–sea energy exchange over the coverage area of a category one hurricane is about 5 TW. Formulas for the effective fetches and durations in the three hurricane sectors are derived from the data. Using these formulas together with the wave growth functions, the full set of wind-wave triplets can be calculated knowing only one of the three. These results may enhance the capability and scope of monitoring hurricanes from space.
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Marchenko, Oleg, and Sergei Solomin. "Efficiency of solar and wind energy use in the countries of Central and North-East Asia." E3S Web of Conferences 209 (2020): 04002. http://dx.doi.org/10.1051/e3sconf/202020904002.
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This paper investigates the effectiveness of renewable energy sources using solar and wind energy in the countries of Central and North-East Asia. The analysis was carried out in two stages. At the first stage, the efficiency of wind and solar installations in different climatic conditions was compared by the criterion of the cost of electricity. At the next stage of analysis, an optimization mathematical model was used to study the system that simultaneously includes wind and solar installations, backup energy sources and batteries. The model takes into account system effects caused by the interaction of the system elements between themselves and with the environment. It solves the problem of mathematical programming — the search for the minimum of the objective function (total costs) at some constrains. The model is used to study the economic efficiency of the large-scale construction of solar power plants in the Gobi Desert. It is shown that the joint use of solar and wind energy gives a positive economic effect, i.e. energy cost are less than with separate use of these energy sources. Under suitable wind conditions such systems reduces the cost of electricity by more than a quarter compared to the option of using solar energy only.
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Cameron, Jennifer H., Murray B. Isman, and Mahesh K. Upadhyaya. "Trichoplusia ni growth and preference on broccoli and eight common agricultural weeds." Canadian Journal of Plant Science 87, no. 2 (April 1, 2007): 413–21. http://dx.doi.org/10.4141/p06-032.
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Larval growth and feeding, and adult ovipositional preference of the cabbage looper, Trichoplusia ni Hübner, were investigated on broccoli (Brassica oleracea var. italica L.) and eight common agricultural weeds: cow cockle (Saponaria vaccaria L.), common groundsel (Senecio vulgaris L.), lamb’s-quarters (Chenopodium album L.), redroot pigweed (Amaranthus retroflexus L.), sheep sorrel (Rumex acetosella L.), shepherd’s purse (Capsella bursapastoris L.), stinkweed (Thlaspi arvense L.), and wild mustard (Sinapsis arvensis L.). Leaves from greenhouse grown plants were removed and fed to 1st instar larvae in a 7-d growth trial. Broccoli-fed larvae grew larger than those fed on cow cockle, redroot pigweed, sheep sorrel, stinkweed, and wild mustard. Only one insect of 64 survived for 7 d on stinkweed. In a leaf disc choice bioassay, 4th instar larvae showed a significant feeding preference for common groundsel over broccoli. Broccoli was preferred for oviposition over three of the weeds (common groundsel, lamb’s-quarters, and shepherd’s purse). Stinkweed showed promise as a dead-end trap species for this insect in broccoli, since more insects oviposited on stinkweed compared with broccoli yet larval survival on stinkweed was almost nil. Key words: Trichoplusia ni, broccoli, Thlaspi arvense, oviposition, feeding deterrence
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Archer, Cristina L., Sicheng Wu, Yulong Ma, and Pedro A. Jiménez. "Two Corrections for Turbulent Kinetic Energy Generated by Wind Farms in the WRF Model." Monthly Weather Review 148, no. 12 (December 2020): 4823–35. http://dx.doi.org/10.1175/mwr-d-20-0097.1.
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AbstractAs wind farms grow in number and size worldwide, it is important that their potential impacts on the environment are studied and understood. The Fitch parameterization implemented in the Weather Research and Forecasting (WRF) Model since version 3.3 is a widely used tool today to study such impacts. We identified two important issues related to the way the added turbulent kinetic energy (TKE) generated by a wind farm is treated in the WRF Model with the Fitch parameterization. The first issue is a simple “bug” in the WRF code, and the second issue is the excessive value of a coefficient, called CTKE, that relates TKE to the turbine electromechanical losses. These two issues directly affect the way that a wind farm wake evolves, and they impact properties like near-surface temperature and wind speed at the wind farm as well as behind it in the wake. We provide a bug fix and a revised value of CTKE that is one-quarter of the original value. This 0.25 correction factor is empirical; future studies should examine its dependence on parameters such as atmospheric stability, grid resolution, and wind farm layout. We present the results obtained with the Fitch parameterization in the WRF Model for a single turbine with and without the bug fix and the corrected CTKE and compare them with high-fidelity large-eddy simulations. These two issues have not been discovered before because they interact with one another in such a way that their combined effect is a somewhat realistic vertical TKE profile at the wind farm and a realistic wind speed deficit in the wake. All WRF simulations that used the Fitch wind farm parameterization are affected, and their conclusions may need to be revisited.
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Karipoğlu, Fatih. "Importance of offshore wind farms Marmara Sea for Turkey’s renewable energy targets: a case study Marmara Sea." Technium: Romanian Journal of Applied Sciences and Technology 2, no. 2 (April 7, 2020): 25–38. http://dx.doi.org/10.47577/technium.v2i2.286.
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In Turkey, current energy generations are not sufficient for the existing energy needs and besides, energy demand is expected to increase by 4-6% percent annually until 2023. Therefore, the government aims to increase the ratio of renewable energy sources in total installed capacity to 30 percent by 2023. Turkey has three quarter seas around itself. So, Turkey has a high level offshore wind potential for energy generations. But there are not any offshore wind farms in Turkey seas. In this study, we aimed at assessing the viability of establishing offshore wind farms of Marmara Sea and to identify favorable sites for such farms using Geographical Information System (GIS) procedures and algorithms. GIS layers were created and a weighted overlay GIS model based on the above mentioned criteria was built to identify suitable sites for hosting a new offshore wind farm. Furthermore, EMODnet (the European Marine Observation and Data Network) and GWA (Global Wind Atlas) were employed for data acquisition to unlock fragmented and hidden marine data resources and to facilitate investment in sustainable coastal and offshore activities. Received technical, social and environmental data from different sources were processed in the GIS and we created the GIS-based model. Results showed that most of Marmara Sea offshore areas were unsuitable. There are only two suitable areas. It is apparent that the growth of offshore wind farms in Turkey will increase provided that the supporting mechanism and the necessary legislation are ensured.
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Wang, Ju, Xin Xie, and Chunsheng Fang. "Temporal and Spatial Distribution Characteristics of Atmospheric Particulate Matter (PM10 and PM2.5) in Changchun and Analysis of Its Influencing Factors." Atmosphere 10, no. 11 (October 28, 2019): 651. http://dx.doi.org/10.3390/atmos10110651.
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With Changchun’s economic development, atmospheric particulate pollution has become a significant challenge in Changchun. The spatiotemporal patterns of particulate matter emissions are an inherent characteristic for particulate matter emissions. By using hourly PM (particulate matter) mass concentration measured at 10 atmospheric automatic monitoring stations and meteorological parameters, the spatiotemporal distribution characteristics of particulate matter (PM10 and PM2.5) and its relationship with meteorological parameters of Changchun have been analyzed. Pollution pathways and source distribution were investigated using HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory) model and cluster analysis. Results indicated that the quarterly average PM2.5 and PM10 mass concentrations in Changchun were higher in the first quarter and the fourth quarter. PM concentrations observed in all seasons generally exhibited two peaks, at 07:00–10:00 and 21:00–23:00, with the exception of PM10 in spring. PM pollution was concentrated mainly in the central, northern, and western areas of Changchun in most seasons, mainly due to anthropogenic activities and soil dust transported outside the region. PM concentrations were negatively correlated with relative humidity and temperature. PM2.5 concentrations were negatively correlated with wind speed, while PM10 concentrations were positively correlated with wind speed. The results of backward trajectory clustered showed that the northwest airflow had the greatest impact on PM of Changchun, except summer.
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Brennenstuhl, M., M. von der Gruen, S. Harbola, A. Koukofikis, R. Padsala, M. Schaaf, V. Coors, and U. Voss. "CFD SIMULATION AND VISUALIZATION BASED INVESTIGATION OF SMALL WIND TURBINE POTENTIAL: A CASE STUDY “NEUER STÖCKACH” FOR STUTTGART." ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences VIII-4/W1-2021 (September 3, 2021): 17–24. http://dx.doi.org/10.5194/isprs-annals-viii-4-w1-2021-17-2021.
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Abstract. In the face of climate change and the energy transition that the German federal government is aiming for, all renewable energy potentials need to be tapped. Unfortunately, small wind turbines play a niche role in Germany and most other countries despite the fact, that although they offer advantages as e.g. almost seasonal independent energy production in close proximity to the consumer on the same low-voltage grid level. One reason beside the lower wind speeds that can be expected closer to the ground is, that in comparison to PV (photovoltaic), for which good yield forecasts can be made using global radiation measurements from nearby weather stations or online databases, the yield of small wind turbines, especially in urban areas, can only be forecasted using on-site measurements due to the influence of the surrounding buildings and topography. This method is time-consuming and costly. To address this, within this work a Computational Fluid Dynamics (CFD) simulation based visualization framework for the investigation of the small wind turbine potential is presented. In this specific case the energy supply company EnBW is planning to refurbish the “Neuer Stöckach” urban quarter on the former “Stöckach” company site. As part of the redevelopment, a comprehensive energy concept is planned to integrate renewable energies. In this context the integration of small wind turbines into the energy concept is examined according to this new methodology.
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Soltani, M. R., and M. Mahmoudi. "Measurements of velocity Field in the wake of an oscillating wind turbine blade." Aeronautical Journal 114, no. 1158 (August 2010): 493–504. http://dx.doi.org/10.1017/s0001924000003985.
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Abstract A series of tests were carried out to study the unsteady wake behaviour behind an aerofoil which is a section of a wind-turbine blade. The model is oscillated in pitch about its quarter chord axis at various reduced frequencies, amplitudes, and mean angles-of-attack. Instantaneous and mean velocity profiles were obtained using total and static pressure at 35 vertically aligned points behind the aerofoil via two similar rakes. The rakes were located at a distance of 1·5 chord length behind the model. An estimation of the real time and average variations of the linear momentum deficit during the oscillation cycle is obtained and has been compared with the corresponding static data. The results show that oscillation amplitude and reduced frequency have pronounced effects on the wake characteristics.
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Cao, Chunyan, and Jun Tao. "Predicting the Areas of Suitable Distribution for Zelkova serrata in China under Climate Change." Sustainability 13, no. 3 (February 1, 2021): 1493. http://dx.doi.org/10.3390/su13031493.
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Predicting the geographic distribution of a species together with its response to climate change is of great significance for biodiversity conservation and ecosystem sustainable development. Zelkova serrata is an excellent shelterbelt tree species that is used for soil and water conservation due to the fact of its well-developed root system, strong soil fixation, and wind resistance. However, the wild germplasm resources of Z. serrata have been increasingly depleted due to the fact of its weak ability to regenerate naturally and the unprecedented damage humans have caused to the natural habitats. The present work using Maxent aimed to model the current potential distribution of this species as well as in the future, assess how various environmental factors affect species distribution, and identify the shifts in the distribution of this species in various climate change scenarios. Our findings show habitat in provinces in the southern Qinling and Huai river basins have high environmental suitability. Temperature seasonality, annual precipitation, annual mean temperature, and warmest quarter precipitation were the most important factors affecting its distribution. Under a climate change scenario, the appropriate habitat range showed northeastward expansion geographically. The results in the present work can lay the foundation for the cultivation and conservation of Z. serrata.
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Moyer, J. R., and R. Hironaka. "Digestible energy and protein content of some annual weeds, alfalfa, bromegrass, and tame oats." Canadian Journal of Plant Science 73, no. 4 (October 1, 1993): 1305–8. http://dx.doi.org/10.4141/cjps93-169.
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Protein digestibility by sheep was greatest in alfalfa (Medicago sativa L.); however, protein digestibility of meadow bromegrass (Bromus biebersteinii Roem and Schutt) and tame oats was similar to or less than that of eight annual weeds. The digestible energy content of five of the eight weeds was similar to or greater than that of alfalfa or bromegrass. Key words: Wild oats, green foxtail, redroot pigweed, lamb’s-quarters, kochia, flixweed
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Bishaw, Dereje, and Megersa Olumana. "Evaluating the Effect of Operating Pressure and Riser Height on Irrigation Water Application under Different Wind Conditions in Ethiopia." Asia Pacific Journal of Energy and Environment 3, no. 1 (June 30, 2016): 41–48. http://dx.doi.org/10.18034/apjee.v3i1.230.
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Efficient and effective use of water resource is crucial to increase crop production. This can be achieved through uniform application of water and by reducing application losses. A field experiment was conducted at Wonji/Shoa Sugarcane Plantation (Ethiopia) to study the effect of sprinkler operating pressure and riser height on water distribution uniformity under different wind conditions. Three levels of operating pressure and two levels of sprinkler riser height, under three different wind conditions, were examined during the experiment. From the research evaporation and drift losses ranging from 11.2% to 16.4% were determined. Potential application efficiency (PAE) of 47.7% to 91.3% and actual application efficiency of low-quarter (AELQ) of 32.9% to 38.6% were achieved under various test combinations. Christiansen’s coefficient of uniformity (CU) of 71.7% to 81.7% and distribution uniformity (DU) of 56% to 75.7% were obtained under different test combinations. The results indicated that increase riser height leads to increase in sprinkler water uniformity. Higher sprinkler water uniformity and low application water loss have been encountered during low wind speed condition.