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Numerical investigation on adiabatic film cooling effectiveness and heat transfer coefficient for effusion cooling over a transverse corrugated surface

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Chinese Journal of Aeronautics 2017年第2期30卷 677-684页

作者： Qu Lihong Zhang Jingzhou tan Xiaoming wang Minmin College of Energy and power Engineering Jiangsu Province Key Laboratory of Aerospace Power System Nanjing University of Aeronautics and Astronautics Nanjing 210016 China Collaborative Innovation Center of Advanced Aero-Engine Beijing 100083 China

Three-dimensional numerical computations are conducted to investigate the effects of the blowing ratio and corrugation geometry on the adiabatic film cooling effectiveness as well as the heat transfer coefficient over a transverse corrugated *** is noticeable that the adiabatic wall temperature on the wavy valley of the transverse corrugated surface is relatively lower than that on the wavy *** corrugation has a relatively obvious influence on the laterallyaveraged adiabatic film cooling effectiveness in the region where the effusion film layer is developed,but has little influence in the front *** to a flat surface,the transverse corrugated surface produces a smaller adiabatic film cooling effectiveness and a higher heat transfer coefficient *** effusion cooling difference between the flat and corrugated surfaces behaves more obviously under a small aspect ratio of the wavy corrugation.

关键词： Adiabatic film cooling effectiveness Effusion cooling Heat transfer Numerical computation Transverse corrugated surface

perfect State Transfer on weighted Abelian Cayley Graphs

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Chinese Annals of Mathematics,Series B 2021年第4期42卷 625-642页

作者： Xiwang CAO Keqin FENG Ying-Ying tan Department of Mathematics Nanjing University of Aeronautics and Astronau-ticsNanjing 210016China Department of Mathematical Sciences Tsinghua UniversityBeijing 100084China School of Mathematics and physics Anhui Jianzhu UniversityHefei 230601China

Recently,there are extensive studies on perfect state transfer(pST for short)on graphs due to their significant applications in quantum information processing and quantum ***,there is not any general characterization of graphs that have pST in *** this paper,the authors present a depiction on weighted abelian Cayley graphs having *** give a unified approach to describe the periodicity and the existence of pST on some specific graphs.

关键词： perfect state transfer Cayley graph Eigenvalues of a graph weighted graph Random walk

Combined effects of topography and bottom friction on shoaling internal solitary waves in the South China Sea

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Applied Mathematics and Mechanics(English Edition) 2019年第4期40卷 421-434页

作者： Dalin tan Jifu ZHOU Xu wANG Zhan wANG Key Laboratory for Mechanics in Fluid Solid Coupling Systems Institute of MechanicsChinese Academy of Sciences School of Engineering Sciences University of Chinese Academy of Sciences

A numerical study to a generalized Korteweg-de Vries (KdV) equation is adopted to model the propagation and disintegration of large-amplitude internal solitary waves (ISws) in the South China Sea (SCS). Based on theoretical analysis and in situ measurements, the drag coefficient of the Chezy friction is regarded as inversely proportional to the initial amplitude of an ISw, rather than a constant as assumed in the previous studies. Numerical simulations of ISws propagating from a deep basin to a continental shelf are performed with the generalized KdV model. It is found that the depression waves are disintegrated into several solitons on the continental shelf due to the variable topography. It turns out that the amplitude of the leading ISw reaches a maximum at the shelf break, which is consistent with the field observation in the ***, a dimensionless parameter defining the relative importance of the variable topography and friction is presented.

关键词： internal solitary wave(ISw) South China Sea(SCS) Chezy friction vari-able topography

Horizontal Connection and Horizontal Mean Curvature in Carnot Groups

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Acta Mathematica Sinica,English Series 2006年第3期22卷 701-710页

作者： Kang Hai tan Xiao ping YANG Department of Applied Mathematics Nanjing University of Science and Technology

In this paper we give a geometric interpretation of the notion of the horizontal mean curvature which is introduced by Danielli Garofalo-Nhieu and pauls who recently introduced sub- Riemannian minimal surfaces in Carnot groups. This will be done by introducing a natural nonholonomic connection which is the restriction （projection） of the natural Riemannian connection on the horizontal bundle. For this nonholonomic connection and （intrinsic） regular hypersurfaces we introduce the notions of the horizontal second fundamental form and the horizontal shape operator. It turns out that the horizontal mean curvature is the trace of the horizontal shape operator.

关键词： Carnot groups Nonholonomic connection Horizontal mean curvature Sub-Riemannian minimal surfaces

Optimal Dividend Strategy in Compound Binomial Model with Bounded Dividend Rates

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Acta Mathematicae Applicatae Sinica 2014年第4期30卷 859-870页

作者： Ji-yang tan Xiang-qun YANG School of Mathematics and Computational Science Xiangtan University College of Mathematics and Computer Science Hunan Normal University

we consider the compound binomial model, and assume that dividends are paid to the shareholders according to an admissible strategy with dividend rates bounded by a *** company controls the amount of dividends in order to maximize the cumulative expected discounted dividends prior to ruin. we show that the optimal value function is the unique solution of a discrete HJB equation. Moreover, we obtain some properties of the optimal payment strategy, and offer a simple algorithm for obtaining the optimal strategy. The key of our method is to transform the value function. Numerical examples are presented to illustrate the transformation method.

关键词： compound binomial model optimal dividend strategy transformation

过渡金属磷化物基材料在电催化析氢中的改性策略:现状及展望

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复合材料学报 2024年第4期41卷 1737-1749页

作者：雷琬莹吴攀司渭滨赵亮谭自强杨鑫鑫乔明涛张婷婷西安建筑科技大学材料科学与工程学院西安710055 定西市产品质量监督检验所定西743000

氢能作为一种零碳燃料,被认为是替代化石能源的理想能源。电催化析氢(HER)是一种绿色环保技术,可以裂解水分子制备氢气。因此开发低廉高效且稳定性好的非贵金属催化剂对于解决能源危机和可持续发展尤为重要。过渡金属磷化物(TMps)具有... 详细信息

氢能作为一种零碳燃料,被认为是替代化石能源的理想能源。电催化析氢(HER)是一种绿色环保技术,可以裂解水分子制备氢气。因此开发低廉高效且稳定性好的非贵金属催化剂对于解决能源危机和可持续发展尤为重要。过渡金属磷化物(TMps)具有良好的导电性、多变的化学组成、丰富的储量和稳定的理化性质,是HER反应重要的催化剂之一。本文首先介绍了HER反应机制及TMps的结构特点,然后总结了TMps的合成方法包括液相合成法和气-固合成法等,接着重点分析了现有TMps的改性策略如形貌调控、缺陷调控、元素掺杂和界面复合,最后对未来TMps的发展方向提出了展望。

关键词：过渡金属磷化物氢能电催化析氢反应改性策略

Optimal maintenance decisions for gamma deteriorating systems

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Journal of Systems Engineering and Electronics 2011年第5期22卷 788-793页

作者： Lin tan Chiming Guo Zhijun Cheng Bo Guo Department of Human Sciences College of Humanities and Social Sciences National University of Defense Technology Changsha 410074 P. R. China Department of Systems Engineering College of Information System and Management National University of Defense Technology Changsha 410073 P. R. China

An optimal replacement model for gamma deteriorating systems is studied. This methodology uses a gamma distribution to model the material degradation, and the impact of imperfect maintenance actions on the system reliability is investigated. The state of a degrading system immediately after the imperfect maintenance action is assumed as a random variable and the maintenance time follows a geometric process. A maintenance policy （N） is applied by which the system will be repaired whenever it experiences Nth preventive maintenance （pM）, and an optimal policy （N＊） could be determined numerically or analytically for minimizing the long-run average cost per unit time. Finally, a numerical example is presented to demonstrate the use of this policy.

关键词： maintenance policy gamma process geometrical process deteriorating system imperfect maintenance.

Strain-Sensitive Current-Voltage Characteristics of ZnSe Nanowire in Metal-Semiconductor-Metal Nanostructure

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Chinese physics Letters 2013年第11期30卷 175-179页

作者： tan Yu wANG Yan-Guo Science College Hunan Agricultural UniversityChangsha 410128 Beijing National Laboratory of Condensed Matter physics Institute of PhysicsChinese Academy of SciencesP.O.Box 603Beijing 100190

Experimental investigation of electrical transport properties is carried out by in situ transmission electron microscopy(TEM)to explore the effect of local strain in ZnSe nanowires(Nws)on improvement of electron transport of Au-ZnSe Nw-Au(M-S-M)*** results show that the threshold voltage due to the Schottky barrier at the metal-semiconductor Nw(M-S)nanocontact is found to decrease significantly when the ZnSe Nw bends at the Au-ZnSe junction by the movable probe which can apply longitudinal compression,leading to current-voltage(I–V)characteristics of the M-S-M nanostructure being transformed from a nearly symmetrical to an asymmetrical *** of the I–V characteristic can be ascribed to significant depression of the Schottky barrier at the M-S nanocontact due to the band gap being narrowed by highly localized *** a result,the I–V characteristics of the M-S-M nanostructure are strain-sensitive and can be modified by local strain intentionally produced in the semiconductor *** modifiable I–V characteristics of M-S-M nanostructure confirm that the strain can be used for improvement of transport property of the semiconductor Nw-based nanoelectronics with the M-S-M nanostructure.

关键词： transport barrier structure

Magnetically responsive porous materials for efficient adsorption and desorption processes

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Chinese Journal of Chemical Engineering 2019年第6期27卷 1324-1338页

作者： peng tan Yao Jiang Xiaoqin Liu Linbing Sun State Key Laboratory of Materials-Oriented Chemical Engineering Jiangsu National Synergetic Innovation Center for Advanced Materials(SICAM)College of Chemical EngineeringNanjing Tech University

Magnetically responsive porous materials possess unique properties in adsorption processes such as magneticinduced separation and heat generation in alternating magnetic fields, which greatly facilitates recycling procedures, favors long-term operation, and improves desorption rate, making conventional adsorption processes highly efficient. with increasing interest in magnetic adsorbents, great progress has been made in designing and understanding of magnetically responsive porous materials varying from monoliths to nanoscale particles used for adsorption including oil uptake, removal of hazardous substances from water, deep desulfurization of fuels, and CO2 capture in the past few years. Therefore, a review summarizing the advanced strategies of synthesizing these magnetically responsive adsorbents and the utilization of their magnetism in practical applications is highly desired. In this review, we give a comprehensive overview of this emerging field, highlighting the strategies of exquisitely incorporating magnetism to porous materials and subtly exploiting their magnetic responsiveness. Further innovations for fabricating or utilizing magnetic adsorbents are expected to be fueled. The potential opportunities and challenges are also discussed.

关键词： Adsorbents Adsorption Desorption Separation porous materials Magnetic composites