Bibliographies thématiques / Valley-wind system

Littérature scientifique sur le sujet « Valley-wind system »

Auteur : Grafiati
Publié le 4 mai 2024

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Articles de revues sur le sujet "Valley-wind system"

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Schmidli, Juerg, Brian Billings, Fotini K. Chow, Stephan F. J. de Wekker, James Doyle, Vanda Grubišić, Teddy Holt et al. « Intercomparison of Mesoscale Model Simulations of the Daytime Valley Wind System ». Monthly Weather Review 139, no 5 (mai 2011) : 1389–409. http://dx.doi.org/10.1175/2010mwr3523.1.

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Three-dimensional simulations of the daytime thermally induced valley wind system for an idealized valley–plain configuration, obtained from nine nonhydrostatic mesoscale models, are compared with special emphasis on the evolution of the along-valley wind. The models use the same initial and lateral boundary conditions, and standard parameterizations for turbulence, radiation, and land surface processes. The evolution of the mean along-valley wind (averaged over the valley cross section) is similar for all models, except for a time shift between individual models of up to 2 h and slight differences in the speed of the evolution. The analysis suggests that these differences are primarily due to differences in the simulated surface energy balance such as the dependence of the sensible heat flux on surface wind speed. Additional sensitivity experiments indicate that the evolution of the mean along-valley flow is largely independent of the choice of the dynamical core and of the turbulence parameterization scheme. The latter does, however, have a significant influence on the vertical structure of the boundary layer and of the along-valley wind. Thus, this ideal case may be useful for testing and evaluation of mesoscale numerical models with respect to land surface–atmosphere interactions and turbulence parameterizations.
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Miao, Miao, Suhua Lou, Yuanxin Zhang et Xing Chen. « Research on the Optimized Operation of Hybrid Wind and Battery Energy Storage System Based on Peak-Valley Electricity Price ». Energies 14, no 12 (21 juin 2021) : 3707. http://dx.doi.org/10.3390/en14123707.

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The combined operation of hybrid wind power and a battery energy storage system can be used to convert cheap valley energy to expensive peak energy, thus improving the economic benefits of wind farms. Considering the peak–valley electricity price, an optimization model of the economic benefits of a combined wind–storage system was developed. A charging/discharging strategy of the battery storage system was proposed to maximize the economic benefits of the combined wind–storage system based on the forecast wind power. The maximal economic benefits were obtained based on scenario analysis, taking into account the wind-power forecast error, and costs associated with the loss of battery life, battery operation, and maintenance. Case simulation results highlight the effectiveness of the proposed model. The results show that the hybrid wind–storage system is not only able to convert cheap electricity in the valley period into expensive electricity in the peak period, thus resulting in higher economic benefits, but can also balance the deviation between actual output and plans for the wind power generator to decrease the loss penalty. The analyzed examples show that, following an increase in the deviation of the forecast wind power, the profit of the combined wind–storage system can increase by up to 45% using the charging/discharging strategy, compared with a wind farm that does not utilize energy storage. In addition, the profit of the combined wind–storage system can increase by up to 16% compared with separate systems, following an increase in the deviation penalty deviation coefficient.
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Eigenmann, R., S. Metzger et T. Foken. « Generation of free convection due to changes of the local circulation system ». Atmospheric Chemistry and Physics Discussions 9, no 3 (7 mai 2009) : 11367–411. http://dx.doi.org/10.5194/acpd-9-11367-2009.

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Abstract. Eddy-covariance and Sodar/RASS experimental measurement data of the COPS (Convective and Orographically-induced Precipitation Study) field campaign 2007 are used to investigate the generation of near-ground free convection events in the Kinzig valley, Black Forest, Southwest Germany. The measured high-quality turbulent flux data revealed free convection to be induced in situations where high buoyancy fluxes and a simultaneously occurring wind speed collapse were present. The minimum in wind speed – observable by the Sodar measurements through the whole vertical extension of the valley atmosphere – is the consequence of a thermally-induced valley wind system, which changes its wind direction from down to up-valley winds in the morning hours. Buoyant forces then dominate over shear forces within turbulence production. These situations are detected by the stability parameter (ratio of the measurement height to the Obukhov length) calculated from directly measured turbulent fluxes. An analysis of the scales of turbulent motions during the free convection event using wavelet transform confirms the large-eddy scale character of the detected plume-like coherent structures. Regarding the entire COPS measurement period, free convection events (FCEs) in the morning hours occur on about 50% of all days.
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Shrestha, S., et R. P. Regmi. « Winter-time Hydraulic Jump over the Pokhara Valley, Nepal ». Journal of Nepal Physical Society 9, no 1 (25 août 2023) : 98–106. http://dx.doi.org/10.3126/jnphyssoc.v9i1.57739.

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The Pokhara Valley is set to be one of the aviation hubs of Nepal with the opening of an international airport. The complex mid-hill mountainous topography of the Gangi-Himalaya and the characteristic wind system of the valley make safe aviation rather challenging over the valley. This study using the Weather Research and Forecasting modeling system shows that hydraulic jump-like phenomena occur regularly during winter in the western and central part of the Pokhara Valley during late afternoon/early evening when the airport may remain relatively busy. The jump occurs over the western part of the valley when the regional southwesterly plain to mountain wind via the Putalibazar Valley intrudes into the Valley crossing the Deurali-Mattikhan hill. The jump-like flow is accompanied by the formation of a mild reverse roller above the jump region and the head-on convergence with the northeasterly katabatic/drainage wind from Parche-Namarjung along the southeast–northwest oriented valley axis generating an updraft of as much as 0.4 to 0.8 m s-1. The southwesterly overrides northeasterly generating clockwise vertical rotors and high turbulence over the northeastern region of the valley. An early prediction of possible wind hazards at high spatiotemporal resolutions are highly desired to make aviation activities in the region safer for civil aviation.
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Eigenmann, R., S. Metzger et T. Foken. « Generation of free convection due to changes of the local circulation system ». Atmospheric Chemistry and Physics 9, no 21 (12 novembre 2009) : 8587–600. http://dx.doi.org/10.5194/acp-9-8587-2009.

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Abstract. Eddy-covariance and Sodar/RASS experimental measurement data of the COPS (Convective and Orographically-induced Precipitation Study) field campaign 2007 are used to investigate the generation of near-ground free convection conditions (FCCs) in the Kinzig valley, Black Forest, Southwest Germany. The measured high-quality turbulent flux data revealed that FCCs are initiated near the ground in situations where moderate to high buoyancy fluxes and a simultaneously occurring drop of the wind speed were present. The minimum in wind speed – observable by the Sodar measurements through the whole vertical extension of the valley atmosphere – is the consequence of a thermally-induced valley wind system, which changes its wind direction from down to up-valley winds in the morning hours. Buoyancy then dominates over shear within the production of turbulence kinetic energy near the ground. These situations are detected by the stability parameter (ratio of the measurement height to the Obukhov length) when the level of free convection, which starts above the Obukhov length, drops below that of the sonic anemometer. An analysis of the scales of turbulent motions during FCCs using wavelet transform shows the occurrence of large-scale turbulence structures. Regarding the entire COPS measurement period, FCCs in the morning hours occur on about 50% of all days. Enhanced surface fluxes of latent and sensible heat are found on these days.
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Katurji, Marwan, Bob Noonan, Peyman Zawar-Reza, Tobias Schulmann et Andrew Sturman. « Characteristics of the Springtime Alpine Valley Atmospheric Boundary Layer Using Self-Organizing Maps ». Journal of Applied Meteorology and Climatology 54, no 10 (octobre 2015) : 2077–85. http://dx.doi.org/10.1175/jamc-d-14-0317.1.

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AbstractVertical profiles of wind velocity and air temperature from a sound detection and ranging (sodar) radio acoustic sounding system (RASS)-derived dataset within an alpine valley of the New Zealand Southern Alps were analyzed. The data covered the month of September 2013, and self-organizing maps (SOM; a data-clustering approach that is based on an unsupervised machine-learning algorithm) are used to detect topological relationships between profiles. The results of the SOM were shown to reflect the physical processes within the valley boundary layer by preserving valley boundary layer dynamics and its response to wind shear. By examining the temporal evolution of ridgetop wind speed and direction and SOM node transitions, the sensitivity of the valley boundary layer to ridgetop weather conditions was highlighted. The approach of using a composite variable (wind speed and potential temperature) with SOM was successful in revealing the coupling of dynamics and atmospheric stability. The results reveal the capabilities of SOM in analyzing large datasets of atmospheric boundary layer measurements and elucidating the connectivity of ridgetop wind speeds and valley boundary layers.
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Liu, Yuanyuan, Pengcheng Guo et Hao Zhang. « Optimal scheduling for wind-solar-hydro hybrid generation system with cascade hydropower considering regulation energy storage requirements ». Journal of Physics : Conference Series 2707, no 1 (1 février 2024) : 012100. http://dx.doi.org/10.1088/1742-6596/2707/1/012100.

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Abstract Large-scale integration of renewable energy into the grid can lead to significant changes in the net load, peak-to-valley difference, peak and valley occurrence time of the power system. As a result, the power of hydropower plants must take a rapid adjustment response. Aiming at the coordinated operation of multiple energy sources, such as wind power, solar power, cascade hydropower station and energy storage pumping station, a coordinated scheduling model is proposed which can fully improve the consumption capacity of wind and solar power by aiming at the maximum power generation, minimum net load fluctuation and minimum wind and solar abandonment. Through the configuration of three different pumping station capacities, the influence of energy storage pumping station capacity on the complementary power generation system is analyzed. When the pumping station capacity is large enough, the output of the wind and solar can be completely consumed. The studies show that the cascade power station and pump energy storage regulation have a strong net load filling valley effect, which can effectively reduce the impact of wind and solar access on system operation, maintain the efficient and stable operation of the unit, and ensure the absorption rate of renewable energy.
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Yunli, Yue, Sun Beibei, Yue Hao, Chen Dan, Zhou Yi et Lu Jun. « An optimized demand-response operation method of regional integrated energy system considering 5G base station energy storage ». Journal of Physics : Conference Series 2121, no 1 (1 novembre 2021) : 012007. http://dx.doi.org/10.1088/1742-6596/2121/1/012007.

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Abstract The scheduling technology of regional integrated energy system is one of the key technologies to realize carbon neutralization by utilizing wind-power. Aiming at the optimal scheduling problem of regional electrothermal integrated energy system considering wind-power utilization and load side energy consumption, this paper proposes an optimized demand-response operation method of regional integrated energy system considering 5G base station energy storage. The regional integrated energy system of load side demand response is constructed based on the comprehensive consideration of technical and economic factors such as wind-power utilization and economic costs and load side peak valley difference. Finally, a two-layer particle swarm optimization method is proposed to solve the model. The experimental results show that the proposed method can effectively achieve wind-power utilization, economic dispatch and reduce the peak valley difference through load side demand response, which can improve the economic efficiency, environmental protection and low-carbon operation of regional integrated energy system.
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Wang, Hsueh-Ming Steve, Karl M. Spohn, LuAnn Piccard et Lei Yao. « Feasibility Study of Wind Power Generation System at Arctic Valley ». Engineering Management Journal 22, no 3 (septembre 2010) : 21–33. http://dx.doi.org/10.1080/10429247.2010.11431869.

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Whiteman, C. David, Sebastian W. Hoch et Gregory S. Poulos. « Evening Temperature Rises on Valley Floors and Slopes : Their Causes and Their Relationship to the Thermally Driven Wind System ». Journal of Applied Meteorology and Climatology 48, no 4 (1 avril 2009) : 776–88. http://dx.doi.org/10.1175/2008jamc2028.1.

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Abstract At slope and valley floor sites in the Owens Valley of California, the late afternoon near-surface air temperature decline is often followed by a temporary temperature rise before the expected nighttime cooling resumes. The spatial and temporal patterns of this evening warming phenomenon, as seen in the March/April 2006 Terrain-Induced Rotor Experiment, are investigated using a widely distributed network of 51 surface-based temperature dataloggers. Hypotheses on the causes of the temperature rises are tested using heavily instrumented 34-m meteorological towers that were located within the datalogger array. The evening temperature rise follows the development of a shallow temperature deficit layer over the slopes and floor of the valley in which winds blow downslope. Background winds within the valley, freed from frictional deceleration from the earth’s surface by this layer, accelerate. The increased vertical wind shear across the temperature deficit layer eventually creates shear instability and mixes out the layer, creating the observed warming near the ground. As momentum is exchanged during the mixing event, the wind direction near the surface gradually turns from downslope to the background wind direction. After the short period of warming associated with the mixing, ongoing net radiative loss causes a resumption of the cooling.
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Thèses sur le sujet "Valley-wind system"

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Metzger, Jutta [Verfasser]. « Wind Systems and Energy Balance in the Dead Sea Valley / Jutta Metzger ». Karlsruhe : KIT Scientific Publishing, 2017. http://www.ksp.kit.edu.

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Largeron, Yann. « Dynamique de la couche limite atmosphérique stable en relief complexe : application aux épisodes de pollution particulaire des vallées alpines ». Phd thesis, Grenoble, 2010. http://www.theses.fr/2010GRENU032.

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L'étude se concentre sur l'analyse de la dynamique de la Couche Limite Atmosphérique stable et hivernale en vallée, notamment dans des situations conduisant à des épisodes de pollution particulaire. L'analyse est effectuée à partir de simulations numériques de type LES et de mesures locales. Dans une première partie, on étudie les vents catabatiques prenant naissance sur les pentes des vallées encaissées. On montre qu'ils sont instationnaires, inhomogènes et turbulents, que leur diffusivité turbulente évolue quadratiquement avec le nombre de Froude et décroît avec la stratification ambiante. On s'intéresse ensuite au champ d'ondes internes généré par ces vents. On trouve que sa fréquence ne dépend que de la stratification et est indépendante des caractéristiques des vents qui lui donnent naissance. Dans une seconde partie, on s'intéresse au système de vents de vallées et aux inversions thermiques dans les vallées Grenobloises. Les conditions météorologiques conduisant aux épisodes de pollution sont étudiées et leur lien avec les mécanismes précédents est explicité. On montre que ces épisodes se déroulent toujours dans un contexte anticyclonique, sont induits par la présence d'une inversion et que leur évolution est liée à celle des régimes de temps. Pendant ces épisodes, le système de vents local est toujours similaire, indépendant du régime synoptique et constitué de vents thermiques, dont l'organisation spatiale est gouvernée par la géométrie du site. Ces courants sont contenus dans la couche d'inversion qui persiste pendant toute la durée de l'épisode et n'est pas détruite si l'énergie solaire est insuffisante. Le seuil énergétique correspondant est mis en évidence
The study is focusing on the dynamics of the stably-stratified Atmospheric Boundary Layer in wintertime in valleys, especially during situations leading to PM10 pollution peaks. The analysis is made by means of LES-like numerical simulations and local measurements. In a first part, we study the katabatic wind created over the slopes of a narrow valley. We show that they are intermittent and turbulent and that their turbulent diffusivity is proportional to the square of a Froude number, and decreases with the ambient stratification. We also study the internal wave field generated by these winds and find that this frequency depends only on the stratification and seems to be independent of the characteristics of its source. In a second part, we study the valley wind system and the thermal inversions which occur by winter conditions in the valleys of the Grenoble area. Meteorological conditions leading to pollution episodes in the Grenoble valleys are also studied and their link with the previous mechanisms are explained. We show that these episodes take place during anticyclonic conditions, are induced by thermal inversion and that their evolution is linked to that of the weather regimes. During these episodes, we show that the local winds system is always the same, independent of the synoptical regime and consists of thermally-driven winds, whose spatial organization is controlled by the geometry of the site. These currents are confined into a thermal inversion, which persists during the whole episode, and is however not destroyed during the day if the solar energy is not sufficient. The corresponding energy treshold is highlighted
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Sudol, Peter. « Modelling and analysis of hydrogen-based wind energy transmission and storage systems : HyLink system at Totara Valley : a thesis presented in partial fulfilment of the requirements for the degree of Master of Technology in Energy Management at Massey University, Palmerston North, New Zealand ». 2009. http://hdl.handle.net/10179/786.

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Distributed generation has the potential to reduce the supply-demand gap emerging in New Zealand’s electricity market. Thereby it can improve the overall network efficiency, harness renewable energy resources and reduce the need for upgrading of existing distribution lines. A typical New Zealand rural community consisting of three adjacent farms at Totara Valley near Woodville represents a demonstration site on distributed generation for Massey University and Industrial Research Limited. Local renewable energy resources are being used for the purpose of sustainable development. Alternative micro-scale technologies are being combined to achieve a valuable network support. This paper is an in-depth report on the implementation process of the HyLink system; a system which utilises hydrogen as an energy carrier to balance and transport the fluctuating wind power. The report documents its development from the laboratory stage to commissioning at Totara Valley, which was carried out under direction of Industrial Research Limited. The PEM electrolyser’s performance at different stack temperatures was investigated. It was found that hydrogen production increases at the same voltage with a higher stack temperature. This is due to the improved kinetics of the electrochemical reactions and decreased thermodynamic energy requirement for water electrolysis. The electrolyser efficiency measurement at the half of its maximal power input (247 W) resulted in 65.3%. Thereby the stack temperature attained less than half of the allowed limit of 80°C. The capture of the excess heat by insulation can improve the electrolyser’s efficiency. Pressure tests were performed on the 2 km long pipeline at Totara Valley using hydrogen and natural gas in order to test their permeability. The results were compared with previous studies at Massey University and with data obtained from the industry. The hydrogen permeability was measured to be 5.5 * 10[to the power of]-16 mol m m[to the power of]-2 s[to the power of]-1 Pa[to the power of]-1 for a 2 km MDPE pipe. This is about half the result obtained from previous studies on hydrogen permeability through MDPE at Massey University which was undertaken at room temperature. The reason for this discrepancy is likely to be the lower ambient temperature during the measurement at Totara Valley, which can be supported with the Arrhenius equation. It was furthermore measured that the power loss due to hydrogen diffusion through the pipeline walls during the fuel cell operation is about 1.5 W at the current system operation mode. A techno-economic analysis of the system was undertaken applying the micro-power optimisation software HOMER as a simulation tool. Two operation modes of the system were investigated, the load following and the peak demand compensating. The simulation results reveal that the durability and the cost of the electrochemical energy conversion devices; electrolyser and fuel cell, are the main hurdles which need to be overcome on the path in introducing hydrogen based energy systems like HyLink. Finally, economic optimisation modelling of the small-scale system by best component alignment was performed. It was found that the electrolyser capacity down-rating of 80% in relation to the wind turbine capacity, leads to a minimal system levelised cost. In addition to this, the impact of various wind turbine/electrolyser subsystems and pipeline storage capacities on the fuel cell capacity factor and on the system levelised cost in the load following operation mode was analysed. The outcomes can be useful for further HyLink related energy system planning.
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Razím, Matyáš. « Vliv reliéfu Hrubého Jeseníku na vzdušné proudění ». Master's thesis, 2019. http://www.nusl.cz/ntk/nusl-411446.

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The thesis is concerned with a prominent phenomenon of the mountain areas - the anemo- orographic systems which occur as a consequence of the collaboration of prevailing winds and of the large windward valleys, the summit flattened surfaces and the leeward slopes. Their presence has a vast influence of numerous physical-geographical realms, mainly due to the highly uneven spatial snow cover distribution within these systems. The focus of the thesis lies on the highest elevations of the Hrubý Jeseník Mts. which reach or exceed the alpine treeline. In this area, the anemo-orographic systems were already defined earlier but a thorough description and of their presence and activity has not been carried out so far, which is the main aim of the thesis. A detailed and spatially compact mapping and measurement of the flag or banner trees has been performed, as these, thanks to their deformed asymmetric shape, attest to the prevailing or mean wind direction as well as its velocity with a high accuracy. As a secondary and comparative data source the meteorological measurements from the summits of Praděd and Šerák Mounts and a modern and detailed wind model has been used. A verification measurement of snow cover depth at selected locations under presumed strong wind action was executed as well. The acquired...
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Davidson, James D. (James Douglas). « Methods for short-term prediction of wind speeds in the Pacific Northwest Columbia Gorge wind farm region ». Thesis, 2012. http://hdl.handle.net/1957/30474.

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Variable electrical generation (VG) sources such as wind farms are an increasing percentage of total electrical generation in the Bonneville Power Administration (BPA) balancing area and are starting to impact the ability of the regional balancing authority to control the electric grid. Wind farms are not dispatchable and challenge historical electric grid control methods. Successful integration of VG at high penetration levels of wind needs to address increased overall system variability and the rapid power ramp rates caused by wind. One of the new control paradigms needed is accurate wind speed prediction which directly relates to wind farm power output. With an accurate wind speed forecast other generation sources can be dispatched as needed to ensure grid stability. This work uses BPA metrology station (MS) data to make predictions for short-term wind speed where short-term is defined as a one hour prediction horizon. It is shown that, using the available metrology station data and several different prediction methodologies, only small improvements in short-term wind speed prediction can be achieved with the available data for the algorithms analyzed.
Graduation date: 2013
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Livres sur le sujet "Valley-wind system"

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Aeronautical Systems Center (U.S.). History Office., dir. Against the wind : 90 years of flight test in the Miami Valley. [Wright-Patterson Air Force Base, Ohio?] : History Office, Aeronautical Systems Center, Air Force Materiel Command, 1994.

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Chapitres de livres sur le sujet "Valley-wind system"

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Whiteman, C. David. « Diurnal Mountain Winds ». Dans Mountain Meteorology. Oxford University Press, 2000. http://dx.doi.org/10.1093/oso/9780195132717.003.0019.

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Diurnal mountain winds develop over complex topography of all scales, from small hills to large mountain massifs and are characterized by a reversal of wind direction twice per day. As a rule, winds flow upslope, up-valley, and from the plain to the mountain massif during daytime. During nighttime, they flow downslope, down-valley, and from the mountain massif to the plain. Diurnal mountain winds are strongest when skies are clear and winds aloft are weak. Diurnal mountain winds are produced by horizontal temperature differences that develop daily in complex terrain. The resulting horizontal pressure differences cause winds near the surface of the earth to blow from areas with lower temperatures and higher pressures toward areas with higher temperatures and lower pressures. The circulations are closed by return, or compensatory, flows higher in the atmosphere. Four wind systems comprise the mountain wind system, which carries air into a mountain massif at low levels during daytime and out of a mountain massif during nighttime. The slope wind system (upslope winds and downslope winds) is driven by horizontal temperature contrasts between the air over the valley sidewalls and the air over the center of the valley. The along-valley wind system (up-valley winds and down-valley winds) is driven by horizontal temperature contrasts along a valley’s axis or between the air in a valley and the air over the adjacent plain. The cross-valley wind system results from horizontal temperature differences between the air over one valley sidewall and the air over the opposing sidewall, producing winds that blow perpendicular to the valley axis and toward the more strongly heated sidewall. The mountain-plain wind system results from horizontal temperature differences between the air over a mountain massif and the air over the surrounding plains, producing large-scale winds that blow up or down the outer slopes of a mountain massif. The mountain-plain circulation and its upper level return flow are not confined by the topography but are carried over deep layers of the atmosphere above the mountain slopes. Because diurnal mountain winds are driven by horizontal temperature differences, the regular evolution of the winds in a given valley is closely tied to the thermal structure of the atmospheric boundary layer within the valley, which is characterized by a diurnal cycle of buildup and breakdown of a temperature inversion.
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Ruskin, John. « The King of the Golden River or The Black Brothers : A Tale of Stiria ». Dans Victorian Fairy Tales. Oxford University Press, 2016. http://dx.doi.org/10.1093/owc/9780198737599.003.0006.

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Chapter I How The Agricultural System Of The Black Brothers Was Interfered With By South-West Wind, Esquire In a secluded and mountainous part of Stiria,* there was, in old time, a valley of the most surprising and luxuriant fertility. It was surrounded,...
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Zhao, Xulei. « Optimal Dispatch of Combined Heat and Power System Considering Adequacy Resources on Demand Side ». Dans Advances in Energy Research and Development. IOS Press, 2022. http://dx.doi.org/10.3233/aerd220031.

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In order to improve the flexibility of the power system, alleviate the problem of wind power curtailment in the heating season in North China, Northeast China and Northwest China, and realize the coordinated operation of the demand side and supply side resources, this paper proposes that the demand side resources include the flexible heat load considering the users’ thermal comfort, the peak-valley time-of-use electricity price demand response, and the orderly charge and discharge of electric vehicles into the power grid. On this basis, the green economic dispatching model of combined heat and power system is established. Then, the Benders decomposition method is used to realize the decomposition and iterative of the thermoelectric system in the outer layer, and the improved particle swarm optimization algorithm is nested in the inner layer for optimizing the solution. Example analysis were given to show that the proposed strategy and model can effectively reduce the total cost of system power supply and improve the accommodation of wind power.
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Gupta, Avijit. « Rivers of Southeast Asia ». Dans The Physical Geography of Southeast Asia. Oxford University Press, 2005. http://dx.doi.org/10.1093/oso/9780199248025.003.0014.

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Southeast Asia, in general, is a subcontinent with surplus water, as evidenced by the formerly widespread tropical rainforests. Most of the region receives at least 2000 mm of rainfall annually, and a positive water balance prevails for the majority of months. Four very large rivers (the Irrawaddy, Salween, Mekong, and Sông Hóng or Red) originate close to each other on the eastern Tibetan Plateau north of the region, and flow through large structure-guided valleys towards the southeast like outstretched fingers. Other major rivers of the region (Chao Phraya, Pahang, Brantas, Mahakam, etc.) start and end within Southeast Asia. The upland slopes are drained by a large number of tributaries, and short, wide estuaries wind through coastal plains. Table 4.1 lists selective physical dimensions of the large rivers of Southeast Asia. Except the Mekong, a part of whose discharge consists of seasonal snowmelt from the Tibetan Plateau, the rivers are rain-fed; and the majority tend to show a seasonal pattern of discharge corresponding to either the southwestern or the northeastern monsoon, depending on the location. The wide riverine lowlands of the previous chapter are structural depressions, filled in mostly by the alluvium of the major rivers that occupy them. The Irrawaddy and its main tributary, the Chindwin, flow through the Central Myanmar Lowland. The channel of the Chao Phraya is located within the Central Plain of Thailand. Further to the east, the Mekong has filled the eponymous lowland. The Salween, in contrast, flows almost entirely in 1000 m gorges cut into plateaux and mountains. The Sông Hóng flows in a narrow valley except for the last 250 km from the coast, where it traverses the coastal plain of north Viet Nam. The present coastline of Southeast Asia, however, is a temporary pause in the geological evolution of the drainage system, and as described in Chapter 2, only appeared in the Holocene. The rivers of the ice age Pleistocene used to continue further. What now are individual major streams in many instances used to be parts of the channel network of a much larger system.
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Brody-Heine, Siena, Marwan Katurji et Jiawei Zhang. « Observed Wind Vector Change Across New Zealand’s National Network of Fire-Weather Stations in Predicting Fire Risk ». Dans Advances in Forest Fire Research 2022, 1248–54. Imprensa da Universidade de Coimbra, 2022. http://dx.doi.org/10.14195/978-989-26-2298-9_189.

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Wildfire spread is influenced significantly by weather fluctuations. Specifically, wind speed and direction (wind vector) change can drastically alter fire intensity and spread. Wind vector change can result from synoptic or mesoscale weather systems and small-scale meteorological processes, such as thermal circulations and low-level wind shear in complex terrain. These small-scale processes are usually underrepresented in numerical weather forecasting models, usually needing to be resolved by more expensive sub-kilometre grid resolution simulations. Recent New Zealand wildfires, such as 2017 Port Hills and 2019 Pigeon Valley wildfires, experienced wind change due to local sea breezes and strong nocturnal downslopes flows, exacerbating fire behaviour. The aim of this research is to investigate if vector wind change (VWC) can be a metric to better represent the effect of mesoscale and microscale weather and the subsequent impact in extreme fire behavior. This was achieved utilizing hourly VWC, or the difference in magnitude of the hourly wind vectors, from the Fire and Emergency New Zealand (FENZ) national network of more than 200 weather monitoring stations. An additional variable, wind direction change (WDC), was also calculated to include the degree change of wind direction. To identify high-risk stations, the top 20% of stations for VWC and WDC were calculated and investigated spatially across the New Zealand landscape. The high-risk stations are located primarily on the South Island, inland and in areas of complex terrain. There is little to no variation of these stations when mapped in each synoptic type, suggesting that the main factor in determining high VWC and WDC is meso and microscale terrain driven meteorology as opposed to larger synoptic regimes. Critically, the current fire risk metric, the Fire Weather Index, does not include wind direction changes at high windspeeds. Therefore, the inclusion of VWC and WDC as additional metrics in fire risk calculations could increase operational understanding of high-risk locations and terrain impacts on extreme and unpredictable fire behavior.
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Ogallo, Laban A., et Silvery B. Otengi. « Monitoring Agricultural Drought : The Case of Kenya ». Dans Monitoring and Predicting Agricultural Drought. Oxford University Press, 2005. http://dx.doi.org/10.1093/oso/9780195162349.003.0028.

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Agriculture is the mainstay of Kenya’s economic development and accounts for about 30% of the country’s gross domestic product, 60% of export earnings, and 70% of the labor force. This sector is the largest source of employment (Government of Kenya, 1995). More than 85% of the population survives in one way or the other on agricultural activities (crops and livestock). Agriculture in Kenya is mainly rain-fed, with little irrigation. About 46% of the rural population live below the poverty line, with 70% of them below food poverty line. Like many parts of the tropics, the majority of agricultural activities in Kenya are rain dependent. Small-scale farmers, pastoralists, and wildlife are most often affected by drought, with crops withering and livestock as well as wildlife dying. Drought of more than one season overwhelms the social fabric, as crops, livestock, wild animals, and humans die. Such droughts affect pastoral communities (e.g., the Masai in Kenya and Tanzania) by killing livestock and game animals, forcing these communities to invade the nearby towns and cities to find remnants of patches of grass still left there or grass growing at the roadsides. The death of game animals affects ecotourism. Interannual climate variability that often leads to the recurrence of climate extremes such as droughts has far-reaching impacts on agricultural production. Figure 18.1 shows below-normal rainfall during different years that are often associated with droughts in Kenya. These rainfall deficits are caused by the anomalies in the circulation patterns that can extend from local or regional to very large scales. Some patterns that are responsible for spatial and temporal distribution of rainfall in Kenya include the Intertropical Convergence Zone (ITCZ), subtropical anticyclones, monsoonal wind systems, tropical cyclones, easterly/westerly wave perturbations, subtropical jet streams, East African low-level jet stream, extratropical weather systems, teleconnection with El Niño/Southern Oscillation (ENSO), and quasi-biennial oscillation (Ogallo, 1988, 1991, 1994). In addition, complex physical features such as large inland lakes, mountains, and complex orographic patterns (e.g., the Great Rift Valley) influence rainfall patterns. Lake Victoria in western Kenya is also one of the largest freshwater lakes in the world and has its own strong circulation patterns in space and time.
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« bianzhong bell chime bili a double-reed cylindrical instrument bo cymbals Chaozhou Xianshi String music in Chaozhou chiba vertical bamboo flute chui blowing, a category of folk classification for music instruments, meaning wind instruments Chuige Hui Society of wind songs da beating, a category of folk classification for music instruments, meaning percussion instruments Dadiao Qüzi a local singing narrative genre in Henan Province daqü large suite di bamboo flute erhu two-string bowed lute Erquan Yingyue Moonlight reflected on the water of Erquan Spring, an erhu piece played by Abing Fanglü Pasture donkey, a wind and percussion ensemble piece played in Chuige Hui in Hebei Province fengshou konghou arched harp Ge hide, a category of ancient classification for musical instruments gonche Chinese system of notation gu drum guan a double-reed cylindrical instrument, basically the same as the ancient bili Guangdong Yinyue Cantonese music, a genre of instrumental ensemble in Guangdong Province Guangling San Tune of Guangling, a qin piece Guchui yue drum and blowing music gudi bone flute haidi small suona (small conical oboe) hua painting, one category of the literati’s self-cultivation and entertainment hujiao horn Ji Kong Yuewu Worshiping music and dance to Confucius Jiangnan Sizhu String and wind ensemble in the south area of the Yangtze River Valley jianzi pu simplified character notation Jin metal, a category of ancient classification for musical instruments jinghu two-string bowed lute, like a small erhu but with its soundbox made of bamboo ». Dans Tradition & ; Change Performance, 32. Routledge, 2012. http://dx.doi.org/10.4324/9780203985656-4.

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Actes de conférences sur le sujet "Valley-wind system"

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He, Shuaijia, Qiang Zhou, Junyong Liu, Zhicheng Ma, Lei Di et Jinxiong Zhao. « Impact of Wind-Solar-Storage System Operation Characteristics on the Peak-Valley-Difference of Power Grid ». Dans 2023 3rd Power System and Green Energy Conference (PSGEC). IEEE, 2023. http://dx.doi.org/10.1109/psgec58411.2023.10255879.

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Rahm, S. « Airborne cw Doppler Lidar - ADOLAR ». Dans Coherent Laser Radar. Washington, D.C. : Optica Publishing Group, 1995. http://dx.doi.org/10.1364/clr.1995.tua1.

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For the airborne measurement of the wind field, knowledge of the exact velocity and orientation of the plane is mandatory. Any small deviation in these parameter will cause an error in the estimation of the wind field. The conical scanning airborne cw CO2 Doppler lidar ADOLAR has been designed to gain experience concerning the correction of the inertial reference system on board the aircraft using the ground return as well as for testing different signal processing algorithms. Beside this the instrument can also be used for the measurement of small scale wind phenomena e.g. valley wind or flow around a hill.
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James B. Rossman, P. E., P. E. Anthony M. Murphy, P. E. Kristin Britt Hensley et P. E. David C. Deloach. « Evaluating the Power Quality Impacts of Large-Scale Solar and Wind-Generation Applications on Tennessee Valley Authority’s (TVA) Power System ». Dans SoutheastCon 2019. IEEE, 2019. http://dx.doi.org/10.1109/southeastcon42311.2019.9020425.

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Li, Gong, et Jing Shi. « Comparison of Different Time Series Methods for Short-Term Forecasting of Wind Power Production ». Dans ASME 2010 4th International Conference on Energy Sustainability. ASMEDC, 2010. http://dx.doi.org/10.1115/es2010-90270.

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Reliable short-term predictions of the wind power production are critical for both wind farm operations and power system management, where the time scales can vary in the order of several seconds, minutes, hours and days. This comprehensive study mainly aims to quantitatively evaluate and compare the performances of different Box & Jenkins models and backpropagation (BP) neural networks in forecasting the wind power production one-hour ahead. The data employed is the hourly power outputs of an N.E.G. Micon 900-kilowatt wind turbine, which is installed to the east of Valley City, North Dakota. For each type of Box & Jenkins models tested, the model parameters are estimated to determine the corresponding optimal models. For BP network models, different input layer sizes, hidden layer sizes, and learning rates are examined. The evaluation metrics are mean absolute error and root mean squared error. Besides, the persistence model is also employed for purpose of comparison. The results show that in general both best performing Box & Jenkins and BP models can provide better forecasts than the persistence model, while the difference between the Box & Jenkins and BP models is actually insignificant.
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Tutkun, Nedim, Furkan Ungoren et Bisar Alpagut. « Improved load shifting and valley filling strategies in demand side management in a nano scale off-grid wind-PV system in remote areas ». Dans 2017 IEEE 14th International Conference on Networking, Sensing and Control (ICNSC). IEEE, 2017. http://dx.doi.org/10.1109/icnsc.2017.8000060.

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France, Todd, Eric Wiemers, Stephen E. Butterworth, Yahia Baghzouz et Robert F. Boehm. « Renewable Energy for Federal Land Management Agencies in Southern Nevada ». Dans ASME 2008 2nd International Conference on Energy Sustainability collocated with the Heat Transfer, Fluids Engineering, and 3rd Energy Nanotechnology Conferences. ASMEDC, 2008. http://dx.doi.org/10.1115/es2008-54230.

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The National Park Service, the U.S. Fish and Wildlife Service, and the USDA Forest Service governmental agencies in southern Nevada have collaborated with the Center for Energy Research at the University of Nevada, Las Vegas to explore the feasibility of becoming energy neutral by 2010. The three federal agencies have set a goal to offset their combined annual energy demand (currently supplied by local utility companies) with an equal amount of power produced by renewable energy sources. The study results indicate that the three federal agencies above consume just over 3,000 megawatt-hours of electrical energy per year in and around the Las Vegas Valley. Upon researching various types of renewable energy, it was determined that wind, geothermal, and biomass technologies either failed to have sufficient resources available in southern Nevada or conflicted with the resource management philosophies of the federal agencies. Solar energy is the most abundant feasible source of renewable energy within the study area, and it was determined that a 1.5 megawatt fixed photovoltaic (PV) system is best suited for this project.
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Hurt, Rick, Wooson Yim, Robert Boehm, Mary Jane Hale et Randy Gee. « Advanced Parabolic Trough Field Testing : Real-Time Data Collection, Archiving, and Analysis for the Solargenix Advanced Parabolic Trough ». Dans ASME 2006 International Solar Energy Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/isec2006-99078.

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Solargenix Energy is currently constructing a 64-MWe parabolic trough solar plant in Eldorado Valley, Nevada, just south of Las Vegas. As part of the preparation for construction and operation of the new utility-scale solar plant, Solargenix has collaborated with UNLV and NREL to build a collector test row. The test row is serving as a platform for field testing advanced parabolic trough components before their large-scale deployment. The test row consists of two Solargenix Solar Collector Assemblies (SCAs); each SCA has 12 collector modules (space frames and mirrors). This facility has been used to field test new Solargenix designs for first and second generation collector space frames, advanced reflectors, advanced local controllers (AdLoCs), a hydraulic-based drive system, receiver support arms, low-cost injection-molded bearings, ball joints and collector support pylons. The test-row facility also has equipment for monitoring the following weather data: direct normal irradiance, dry bulb temperature, relative humidity, wind speed and precipitation. Data logging equipment is used to record and track weather data as well as SCA parameters. Site instrumentation is solar-powered (photovoltaics) and uses cellular technology to transmit data to a web-based data collection system. This paper describes construction of this facility, the installation of the data-collection system and some data collected to date.
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So¨zen, Mehmet. « From a Traditional Combustion Course to an Alternative and Renewable Energy Course ». Dans ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-13072.

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With the increased interest and focus on sustainability and energy independence, utilization of renewable energy resources has been receiving a lot of attention. A new course on Alternative and Renewable Energy has been developed in the School of Engineering at Grand Valley State University as both a new technical elective course in thermofluids area as well as an alternative to the existing Combustion Applications course. While this course emphasizes alternative and renewable energy sources and applications, it also encompasses the basics of combustion of hydrocarbon fuels that is not covered in the single compulsory four credit hour thermodynamics course in the mechanical engineering curriculum. In this sense it serves a unique purpose of filling in an important gap in the curriculum. The laboratory used for the combustion course has been enhanced and transformed to be a Combustion and Energy Applications Laboratory. The experimental course that was developed and offered for the first time in fall 2008 tries to utilize to the maximum extent the existing laboratory and the essential and relevant topics of the combustion course, and builds on these with topics and experiments on alternative and renewable energy in forming a coherent course. In this regard, new equipment including a Hy-Expert™ Instructor Fuel Cell System, portable self-contained educational training units for solar photovoltaic, wind energy, and hydrogen energy have been purchased and added to the lab to complement the existing equipment. Other additions that are under way for enhancing this course are also described in this paper. This paper also discusses how the course and the laboratory were developed, the difficulties encountered, feedback obtained from the students as well as the overall experience and recommendations of the instructor.
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Li, Ni, Arianna Fatahi, Dennis Lee, Jim Y. Kuo et He Shen. « Wind Effects on Power Generation of Solar Farm in California ». Dans ASME 2019 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/imece2019-11859.

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Abstract In comparison to fossil fuels, solar energy is a more sustainable option due to its high availability and less environmental impact. Improving the efficiency of solar farms has been a primary concern of solar energy research. Many studies focus on the control of the tilt angle of solar modules to maximize their solar radiation reception and energy generation. However, an increase in solar radiation is accompanied by an increase in module temperature, which is known to be a significant parameter that reduces the power generation efficiency. Wind is another influential factor that helps Photovoltaic systems maintain a low operating temperature by enhancing the rate of heat transfer. Therefore, solar radiation and wind behavior are both critical parameters that must be considered to optimize solar panel performance. In this paper, the effect of wind conditions on solar panel performance will be examined. The solar panel energy output model will be built by empirically considering the irradiation, ambient temperature, wind speed, and wind direction. The published weather data and energy output data for the year 2017–2018 have been collected from Antelope Valley Solar Ranch, located in Lancaster, California. Four models have been proposed and the results indicate that the model which incorporates the wind conditions has the highest accuracy in approximating the energy production of solar farms. Among the factors that affect the temperature of solar panels and further the efficiency of solar panels including solar irradiation, convection, conduction, wind plays a major role in convective heat transfer. Based on this model, the potential improvement of energy generation via introducing a horizontal installation angle and adjusting this angle monthly according to the wind conditions is further analyzed. These results will help designers improve the design of solar farms by taking into consideration the local weather conditions.
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Rapports d'organisations sur le sujet "Valley-wind system"

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Author, Not Given. Small Wind Electric Systems : A Guide Produced for the Tennessee Valley Authority (Revised) (Brochure). Office of Scientific and Technical Information (OSTI), juin 2009. http://dx.doi.org/10.2172/15007775.

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