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Search Results: 1 - 10 of 105832 matches for " Hang Zhang "
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A Literature Review of Stochastic Programming and Unit Commitment  [PDF]
Hang Dai, Ni Zhang, Wencong Su
Journal of Power and Energy Engineering (JPEE) , 2015, DOI: 10.4236/jpee.2015.34029
Abstract:

The study of unit commitment (UC) aims to find reasonable schedules for generators to optimize power systems’ operation. Many papers have been published that solve UC through different methods. Articles that systematically summarize UC problems’ progress in order to update researchers interested in this field are needed. Because of its promising performance, stochastic programming (SP) has become increasingly researched. Most papers, however, present SP’s UC solving approaches differently, which masks their relationships and makes it hard for new researchers to quickly obtain a general idea. Therefore, this paper tries to give a structured bibliographic survey of SP’s applications in UC problems.

Fixed points and controllability in delay systems
Hang Gao,Bo Zhang
Fixed Point Theory and Applications , 2006,
Abstract: Schaefer's fixed point theorem is used to study the controllability in an infinite delay system x ′ ( t ) = G ( t , x t ) + ( B u ) ( t ) . A compact map or homotopy is constructed enabling us to show that if there is an a priori bound on all possible solutions of the companion control system x ′ ( t ) = λ [ G ( t , x t ) + ( B u ) ( t ) ] , 0 < λ < 1 , then there exists a solution for λ = 1 . The a priori bound is established by means of a Liapunov functional or applying an integral inequality. Applications to integral control systems are given to illustrate the approach.
Fixed points and controllability in delay systems
Gao Hang,Zhang Bo
Fixed Point Theory and Applications , 2006,
Abstract: Schaefer's fixed point theorem is used to study the controllability in an infinite delay system . A compact map or homotopy is constructed enabling us to show that if there is an a priori bound on all possible solutions of the companion control system , then there exists a solution for . The a priori bound is established by means of a Liapunov functional or applying an integral inequality. Applications to integral control systems are given to illustrate the approach.
Fixed points and controllability in delay systems
Hang Gao,Bo Zhang
Fixed Point Theory and Applications , 2006, DOI: 10.1155/fpta/2006/41480
Abstract: Schaefer's fixed point theorem is used to study the controllability in an infinite delay system x ¢ € 2(t)=G(t,xt)+(Bu)(t). A compact map or homotopy is constructed enabling us to show that if there is an a priori bound on all possible solutions of the companion control system x ¢ € 2(t)= [G(t,xt)+(Bu)(t)],0< <1, then there exists a solution for =1. The a priori bound is established by means of a Liapunov functional or applying an integral inequality. Applications to integral control systems are given to illustrate the approach.
Null controllability of some degenerate wave equations
Muming Zhang,Hang Gao
Mathematics , 2015,
Abstract: This paper is devoted to a study of the null controllability problems for one-dimensional linear degenerate wave equations through a boundary controller. First, the well-posedness of linear degenerate wave equations is discussed. Then the null controllability of some degenerate wave equations is established, when a control acts on the non-degenerate boundary. Different from the known controllability results in the case that a control acts on the degenerate boundary, any initial value in state space is controllable in this case. Also, an explicit expression for the controllability time is given. Furthermore, a counterexample on the controllability is given for some other degenerate wave equations.
Thermodynamic and Experimental Analysis of an Ammonia-Water Absorption Chiller  [PDF]
Dingfeng Kong, Jianhua Liu, Liang Zhang, Hang He, Zhiyun Fang
Energy and Power Engineering (EPE) , 2010, DOI: 10.4236/epe.2010.24042
Abstract: A single stage ammonia-water absorption chiller with complete condensation is designed, built and tested. The apparatus is designed for a cooling capacity of 2814 W, which is obtained using electric heater as heating source. The thermodynamic models have been derived using the First and Second Laws. Calculated results are compared with experimental data. The results show that the cooling capacity of experimental apparatus is found between 1900 and 2200 W with the actual coefficient of performance (COP) between 0.32 and 0.36. The contribution of the components to internal entropy production is analyzed. It shows that the larger irreversibility is caused by spanning the largest temperature and dissipated thermal energy by heat transfer losses at the generator and evaporator. In the experimentation, the low pressure is lower than the designed value. This is a consequence of a large capacity in the falling film absorber which performs as expected. This decreases the evaporation pressure, and the evaporating temperature could be reduced to the designed value.
The optical tomography of tissues by a δ sound field
基于δ声波场的生物组织光学断层成像研究

Zhang Hang,
张航

物理学报 , 2004,
Abstract: 利用δ声波场和近红外光漫射理论实现生物组织的断层成像是一种新颖医学成像方法 .通过构建一个δ声波场并作用到生物组织中 ,仅改变组织内作用点上的光学特性参数 ,并影响近红外光在组织中的传播特性而改变组织表面的光强分布 .利用组织表面光强改变量与作用点上组织光学参数改变量之间的内在关系 ,可以通过对δ声波场作用点上断层的扫描实现组织内部的断层成像 .该方法具有广泛的临床医学应用前景 ,为乳腺癌的早期检测提供一种有效方法
A PP GOODNESS-OF-FIT TEST AND ITS ASYMPTOTIC PROPERTIES
PP 型拟合优度检验

ZHANG HANG,
张航

系统科学与数学 , 1988,
Abstract: By the use of the Projection Pursuit method,we get a multivariate goodness-of-fit testwith the classical X~2-test statistic as an index.The asymptotic propeerties of the test are dis-cussed,and the asymptotic rejection region is obtained by bootstraping the test statistic.
Ubiquitous Log Odds: A Common Representation of Probability and Frequency Distortion in Perception, Action, and Cognition
Hang Zhang,Laurence T. Maloney
Frontiers in Neuroscience , 2012, DOI: 10.3389/fnins.2012.00001
Abstract: In decision from experience, the source of probability information affects how probability is distorted in the decision task. Understanding how and why probability is distorted is a key issue in understanding the peculiar character of experience-based decision. We consider how probability information is used not just in decision-making but also in a wide variety of cognitive, perceptual, and motor tasks. Very similar patterns of distortion of probability/frequency information have been found in visual frequency estimation, frequency estimation based on memory, signal detection theory, and in the use of probability information in decision-making under risk and uncertainty. We show that distortion of probability in all cases is well captured as linear transformations of the log odds of frequency and/or probability, a model with a slope parameter, and an intercept parameter. We then consider how task and experience influence these two parameters and the resulting distortion of probability. We review how the probability distortions change in systematic ways with task and report three experiments on frequency distortion where the distortions change systematically in the same task. We found that the slope of frequency distortions decreases with the sample size, which is echoed by findings in decision from experience. We review previous models of the representation of uncertainty and find that none can account for the empirical findings.
The Best Nanoparticle Size Distribution for Minimum Thermal Conductivity
Hang Zhang,Austin J. Minnich
Physics , 2014,
Abstract: Which sizes of nanoparticles embedded in a crystalline solid yield the lowest thermal conductivity? Nanoparticles have long been demonstrated to reduce the thermal conductivity of crystals by scattering phonons, but most previous works assumed the nanoparticles to have a single size. Here, we use optimization methods to show that the best nanoparticle size distribution to scatter the broad thermal phonon spectrum is not a similarly broad distribution but rather several discrete peaks at well-chosen nanoparticle radii. For SiGe, the best size distribution yields a thermal conductivity below that of amorphous silicon. Further, we demonstrate that a simplified distribution yields nearly the same low thermal conductivity and can be readily fabricated. Our work provides important insights into how to manipulate the full spectrum of phonons and will guide the design of more efficient thermoelectric materials.
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