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The third type DC flow in pulse tube cryocooler

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Science China(Technological Sciences) 2009年第12期52卷 3491-3496页

作者： ZHOU yuan gu Chao CAI HuiKun Key Laboratory of Cryogenics Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijing 100190China Graduate University of Chinese Academy of Sciences Beijing 100049China

New phenomena discovered in the experimental research of the ultra-high frequency pulse tube cryocooler were *** cause of the new phenomena was analyzed and the third type DC flow was discovered in the pulse tube *** third type DC flow not only deteriorated cooling capacity but also led to temperature instability of the pulse tube *** the fluid network theory and the simple regenerator model,the root of the third type DC flow was concisely investigated in theory. The asymmetric resistance of oscillating flow in pulse tube cryocooler was the key mechanism of the third type DC *** suppression methods were briefly discussed.

关键词： pulse tube cryocooler DC flow fluid network theory flow resistance

Distribution network state estimation based on attention-enhanced recurrent neural network pseudo-measurement modeling

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Protection and Control of Modern Power Systems 2023年第2期8卷 244-259页

作者： Yaojian Wang Jie gu Lyuzerui yuan Department of Electrical Engineering School of ElectronicsInformation and Electrical EngineeringShanghai Jiao Tong University209 of Smart Grid Building800 Dong Chuan RdShanghai 200240China

Because there is insufficient measurement data when implementing state estimation in distribution networks,this paper proposes an attention-enhanced recurrent neural network(A-RNN)-based pseudo-measurement modeling ***,based on analyzing the power series at the source and load end in the time and frequency domains,a period-dependent extrapolation model is established to characterize the power series in those *** complex mapping functions in the model are automatically represented by A-RNNs to obtain an A-RNNs-based period-dependent pseudo-measurement generation *** distributed dynamic state estimation model of the distribution network is established,and the pseudo-measurement data generated by the model in real time is used as the input of the state estimation model together with the measurement *** experimental results show that the method proposed can explore in depth the complex sequence characteristics of the measurement data such that the accuracy of the pseudo-measurement data is further *** results also show that the state estimation accuracy of a distribution network is very poor when there is a lack of measurement data,but is greatly improved by adding the pseudo-measurement data generated by the model proposed.

关键词： State estimation Pseudo measurement Recurrent neural network Attention mechanism Time-frequency domain analysis Distribution network

Sensitivity of Sample for Simulation-Based Reliability Analysis Methods

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Computer Modeling in Engineering & Sciences 2021年第1期126卷 331-357页

作者： Xiukai yuan Jian gu Shaolong Liu School of Aerospace and Engineering Xiamen UniversityXiamen361005China Institute for Risk and Reliability Leibniz Universitat HannoverHannoverGermany

In structural reliability analysis,simulation methods are widely *** statistical characteristics of failure probability estimate of these methods have been well *** this study,the sensitivities of the failure probability estimate and its statistical characteristics with regard to sample,called‘contribution indexes’,are proposed to measure the contribution of *** contribution indexes in four widely simulation methods,i.e.,Monte Carlo simulation(MCS),importance sampling(IS),line sampling(LS)and subset simulation(SS)are derived and *** proposed contribution indexes of sample can provide valuable information understanding the methods deeply,and enlighten potential improvement of *** is found that the main differences between these investigated methods lie in the contribution indexes of the safety samples,which are the main factors to the efficiency of the ***,numerical examples are used to validate these findings.

关键词： Reliability analysis Monte Carlo simulation importance sampling line sampling subset simulation

Coleman Automorphisms of Generalized Dihedral Groups

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Acta Mathematica Sinica,English Series 2016年第2期32卷 251-257页

作者： Zheng xing LI yuan Lin LI Colledge of Automation EngineeringQingdao University Department of Mathematics Brock University

Let D be a generalized dihedral group and Autcol（D） its Coleman automorphism group. Denote by Outcol（D） the quotient group of Autcol（D） by Inn（D）, where Inn（D） is the inner automorphism group of D. It is proved that either Outcol（D） = i or Outcol（D） is an elementary abelian 2-group whose order is completely determined by the cardinality of π（D）. Furthermore, a necessary and sufficient condition for Outcol（D） = 1 is obtained. In addition, whenever Outcol（D） ≠ 1, it is proved that Autcol（D） is a split extension of Inn（D） by an elementary abelian 2-group for which an explicit description is given.

关键词： Coleman automorphism generalized dihedral group

Approximation to the Distribution of the Least Squares Estimators in Two Dimensional Cosine Models by Randomly Weighted Bootstrap

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Acta Mathematicae Applicatae Sinica 2013年第4期29卷 765-776页

作者： yuan-yuan ZHAO Rui-xing MING Yao-hua WU Department of Statistics and Finance University of Science and Technology of China School of Mathematical Sciences Nanjing Normal University Institute of Finance and Statistics Nanjing Normal University School of Statistics and Mathematics Zhejiang Gongshang University

Recently, Kundu and gupta （Metrika, 48：83 C 97, 1998） established the asymptotic normality of the least squares estimators in the two dimensional cosine model. In this paper, we give the approximation to the general least squares estimators by using random weights which is called the Bayesian bootstrap or the random weighting method by Rubin （Annals of Statistics, 9：130 C 134, 1981） and Zheng （Acta Math. Appl. Sinica （in Chinese）, 10（2）： 247 C 253, 1987）. A simulation study shows that this approximation works very well.

关键词： two dimensional model least squares estimator Bayesian bootstrap random weighting method

The effects of caudal fin deformation on the hydrodynamics of thunniform swimming under self-propulsion

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Journal of Hydrodynamics 2020年第6期32卷 1122-1137页

作者： Yi-kun Feng Yu-min Su Huan-xing Liu yuan-yuan Su College of Shipbuilding Engineering Harbin Engineering UniversityHarbin150001China Beijing Institute of Specialized Machinery Beijing100081China Science College Harbin Engineering UniversityHarbin150001China

To investigate the effects of the caudal fin deformation on the hydrodynamic performance of the self-propelled thunniform swimming,we perform fluid-body interaction simulations for a tuna-like swimmer with thunniform *** 3-D vortices are visualized to reveal the role of the leading-edge vortex(LEV)in the thrust *** comparing the swimming velocity of the swimmer with different caudal fin flexure amplitudes fa,it is shown that the acceleration in the starting stage of the swimmer increases with the increase of fa,but its cruising velocity *** results indicate that the caudal fin deformation is beneficial to the fast start but not to the fast cruising of the *** the entire swimming process,the undulation amplitudes of the lateral velocity and the yawing angular velocity decrease as fa *** is found that the formation of an attached LEV on the caudal fin is responsible for generating the low-pressure region on the surface of the caudal fin,which contributes to the ***,the caudal fin deformation can delay the LEV shedding from the caudal fin,extending the duration of the low pressure on the caudal fin,which will cause the caudal fin to generate a drag-type force over a time period in one swimming cycle and reduce the cruising speed of the swimmer.

关键词： Computational fluid dynamics(CFD)numerical simulation self-propulsion caudal fin deformation

Scatter Search Based Particle Swarm Optimization Algorithm for Earliness/Tardiness Flowshop Scheduling with Uncertainty

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International Journal of Automation and computing 2016年第3期13卷 285-295页

作者： Jia-Can Geng Zhe Cui xing-Sheng gu Key Laboratory of Advanced Control and Optimization for Chemical Process Ministry of EducationEast China University of Science and Technology

Considering the imprecise nature of the data in real-world problems, the earliness/tardiness （E/T） fiowshop scheduling problem with uncertain processing time and distinct due windows is concerned in this paper. A fuzzy scheduling model is established and then transformed into a deterministic one by employing the method of maximizing the membership function of middle value. Moreover, an effective scatter search based particle swarm optimization （SSPSO） algorithm is proposed to minimize the sum of total earliness and tardiness penalties. The proposed SSPSO algorithm incorporates the scatter search （SS） algorithm into the frame of particle swarm optimization （PSO） algorithm and gives full play to their characteristics of fast convergence and high diversity. Besides, a differential evolution （DE） scheme is used to generate solutions in the SS. In addition, the dynamic update strategy and critical conditions are adopted to improve the performance of SSPSO. The simulation results indicate the superiority of SSPSO in terms of effectiveness and efficiency.

关键词： Earliness/tardiness (E/T) scheduling fuzzy modeling scatter search (SS) particle swarm optimization (PSO).

New explicit algebraic stress and flux model for active scalar and simulation of shear stratified cylinder wake flow

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Science China(Technological Sciences) 2009年第9期52卷 2536-2546页

作者： HUA ZuLin gu Li xing LingHang DAI WenHong Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes of Ministry of Education College of Environmental Science&EngineeringHohai UniversityNanjing 210098China Yangtze River Scientific Research Institute Wuhan 430010China Centre for Water and Environment Queen’s UniversityKingstonOntarioK7L3N6Canada

On the numerical simulation of active scalar,a new explicit algebraic expression on active scalar flux was derived based on Wikstrm,Wallin and Johansson model (aWWJ model). Reynolds stress algebraic expressions were added by a term to account for the buoyancy effect. The new explicit Reynolds stress and active scalar flux model was then established. Governing equations of this model were solved by finite volume method with unstructured grids. The thermal shear stratified cylinder wake flow was computed by this new model. The computational results are in good agreement with laboratorial measurements. This work is the development on modeling of explicit algebraic Reynolds stress and scalar flux,and is also a further modification of the aWWJ model for complex situations such as a shear stratified flow.

关键词： active scalar explicit algebraic model scalar flux Reynolds stress thermal shear stratified cylinder wake flow numerical simulation

Application of Learning by Design Into the Cultivation of Multiliteracies:A Case Study of College English Teaching Practice at Soochow University

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Language and Semiotic Studies 2018年第1期4卷 125-143页

作者： Wei-xing gu Soochow University China

Multiliteracies are an indispensable component of language abilities in the modern age of information *** proposed by the New London Group in 1996, multiliteracies refer to the abilities needed to obtain the learning resources that are transmitted through different media and modals, and to apply different modes and means to communicate with others to create *** cultivation of multiliteracies is not only a systematic process of constructing knowledge but also a dynamic cycle of designing learning *** undertaking an international multiliteracies project, the New London Group adopted a mode of learning by design to cultivate *** by design includes three progressive components of available design, designing, and redesigned, with available design referring to the learning resources available, designing being the work to be done to make use of the learning resources obtained, and redesigned meaning the regenerated and transformed learning resources that are to become the new learning resources for available *** it comes to the stage of redesigned, the mode of learning by design enters a new *** since learning by design was adopted, it became the main theoretical framework used to cultivate *** college English teaching subsequently developed at Soochow University followed and specified the general principles of learning by design while constructing its own specific mode, trying to integrate available design and designing into a dynamic whole geared toward cultivating multiliteracies(one of the three abilities needed to use English, together with language expression abilities and intercultural communication competences).With regard to available design, efforts were made toward building and expanding various learning resources, facilities, settings, environments, and other learning support systems at Soochow *** was done to provide easy and selectable accesses to the Net^+ based m

关键词： college English teaching abilities to use English multiliteracies learning by design