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Prediction of fish body's passive visco-elastic properties and related muscle mechanical performance in vivo during steady swimming

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Science China(Physics,Mechanics & Astronomy) 2014年第2期57卷 354-364页

作者： ZHANG wei YU YongLiang tong BingGang School of Physics University of Chinese Academy of Sciences

For attaining the optimized locomotory performance of swimming fishes,both the passive visco-elastic properties of the fish body and the mechanical behavior of the active muscles should coordinate with the fish body’s undulatory motion ***,it is difficult to directly measure the visco-elastic constitutive relation and the muscular mechanical performance in *** the present paper,a new approach based on the continuous beam model for steady swimming fish is proposed to predict the fish body’s visco-elastic properties and the related muscle mechanical behavior in *** the lateral travelling-wave-like movement as the input condition,the required muscle force and the energy consumption are functions of the fish body’s visco-elastic parameters,*** Young’s modulus E and the viscosity coefficient in the Kelvin *** investigating the variations of the propagating speed of the required muscle force with the fish body’s visco-elastic parameters,we analyze the impacts of the visco-elastic properties on the energy efficiencies,including the energy utilization ratios of each element of the kinematic chain in fish swimming and the overall *** the constraints of reasonable wave speed of muscle activation and the physiological feasibility,the optimal design of the passive visco-elastic properties can be predicted aiming at maximizing the overall *** analysis is based on the small-amplitude steady swimming of the carangiform swimmer,with typical Reynolds number varying from 2.5×104to 2.5×105,and the present results show that the non-dimensional Young’s modulus is 112±34,and the non-dimensional viscosity coefficient is 13 *** the present estimated ranges,the overall efficiency of the swimming fish is insensitive to the viscosity,and its magnitude is about 0.11±0.02,in the predicted range given by previous study.

关键词： fish swimming visco-elastic properties muscle mechanics efficiency

Special Column for the Distributed Energy System with Renewable Energy and Natural Gas

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Journal of Thermal Science 2020年第5期29卷 1095-1096页

作者： HAN wei ZHU tong GAN Zhongxue Institute of Engineering Thermophysics CASBeijingChina School of Mechanical Engineering Tongji UniversityShanghaiChina ENN Science and Technology Development Co. Ltd.HebeiChina

With the rapid growth of urban population,the contradiction between energy consumption and environment protection has begun to restrict the development of the ecological *** distributed energy network system,which combines the advantages of renewable energy and distributed energy,has gradually emerged and become one of the main development directions of the next-generation energy *** energy network system is a new type of intelligent energy network system that has evolved from the distributed energy system with integration of multiple energy networks and information *** connecting multiple renewable energy and natural gas in the region with end users in a distributed way,it can realize the instant and bidirectional transmission of cold,heat and electricity,and achieve ordering of the entire network through integration and cooperative control of the material flow,energy flow and information flow.

关键词： network integration connecting

Investigation of the dynamic characteristics of a dual rotor system and its start-up simulation based on finite element method

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2013年第4期14卷 268-280页

作者： Zhong-xiu FEI Shui-guang tong Chao wei Institute of Chemical Machinery Engineering Zhejiang University Mechanical Design Institute Zhejiang University Institute of Thermal Engineering and Power Systems Zhejiang University

Recently,the finite element method(FEM) has been commonly applied in the engineering analysis of rotor *** moments,rotary inertia,transverse shear deformation and gravity can be included in computational models of rotor-bearing *** this paper,a finite element model and its solution method are presented for the calculation of the dynamics of dual rotor systems.A typical structure with two rotor shafts is discussed and the procedure for obtaining the coupling motion equations of the subsystems is illustrated.A computer program is developed to solve critical speeds and to simulate the transient *** influence of gyroscopic moments on co-rotation and counter-rotation is analyzed,and the effect of the speed ratio on critical speed is *** dynamic characteristics under different conditions of increasing speed during start-up are demonstrated by comparison with transient nodal *** presented model provides a complete foundation for further investigation of the dynamics of dual rotor systems.

关键词： Dual rotor system Critical speed Transient response Finite element method(FEM)

A system dynamics urban water management model for Macao, China

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Journal of Environmental Sciences 2016年第12期28卷 117-126页

作者： tong wei Inchio Lou Zhifeng Yang Yingxia Li State Key Laboratory of Water Environment Simulation School of Environment Beijing Normal University Beijing 100875 China. Department of Civil and Environmental Engineering University of Macao Macao 999078 China

Urban water resources have been facing significant pressure from population growth, urbanization, and climate change. A system dynamics urban water management model was proposed to simulate the dynamic interactions between urban water demands and society, economy, climate, and water conservation. The residents＇ water conseration willingness was incorporated in the model and water-saving effects were quantified. The simulation results for Macao showed that population size was the main driving force for urban water demand. The change of temperature and precipitation has obvious effects on the landscape water demand. The water demand output is sensitive to the change in population, per capita demand, and temperature. Increased precipitation will reduce urban water demand and increased economic growth will increase water demand. By implementing integrated water conservation measures and imoroved water conservation willinmaess, water demand could be reduced bv 17.5%.

关键词： Macao System dynamics Water conservation willingness Water demand

Robust model selection for positive and unlabeled learning with constraints

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Science China(Information Sciences) 2022年第11期65卷 94-106页

作者： tong wei Hai WANG weiwei TU Yufeng LI Department of Computer Science and Technology Nanjing University 4Paradigm Inc.

Positive and unlabeled(PU) learning is the problem in which training data contains only PU samples. Although PU learning is widely used in real-world applications, its model selection remains challenging. Specifically, traditional model selection methods are often highly sensitive to the class prior as well as the data size, resulting in human overhead in hyperparameter optimization. In this paper, we present a method called ODE(robust model selection) for robust model selection in PU learning. Two novel model evaluators based on the integral probability metric and area under the curve, which are free of the class prior, are introduced, and a variance reduction method is further employed to improve the quality of model selection. In addition, we perform model selection under user-defined constraints and propose a fast halvingstyle searching algorithm to efficiently identify the most promising model configuration. Extensive empirical studies demonstrate that our proposed method performs more robustly and is more computationally efficient than many state-of-the-art methods.

关键词： positive and unlabeled learning model selection automated machine learning

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Influences of Leading-Edge Tubercle Amplitude on Airfoil Flow Field

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Journal of Thermal Science 2023年第4期32卷 1335-1344页

作者： ZHAO Ming wei tong ZHAO Yijia LIU Zhengxian Department of Mechanics School of Mechanical EngineeringTianjin UniversityTianjin300350China Tianjin Key Laboratory of Modern Engineering Mechanics Tianjin UniversityTianjin300350China

The influences of leading-edge tubercle amplitude on airfoil flow field have been analyzed at high angle of *** accuracy of a large eddy simulation(LES)research is validated through quantitative comparisons with corresponding experimental ***,a proper orthogonal decomposition(POD)analysis has been carried out based on the unsteady flow field and the fluid mechanisms of corresponding POD modes have been ***,the influences of leading-edge tubercle amplitude have been *** the streamwise vorticity is larger than that of small amplitude cases,the momentum transfer process at peaks is more obvious for large amplitude,leading to delayed flow *** amplitude and wavelength play important roles in the generation of laminar separation bubble(LSB)at ***,the Karman vortex shedding process takes place at specific trough sections as pairs of periodic spatial structures exist in the dominant POD *** destruction of Karman vortex shedding process is strengthened along with the increase of amplitude.

关键词： leading-edge tubercle airfoil flow field proper orthogonal decomposition

Research on the basic theoretical issues of smart metro construction

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Science China(Technological Sciences) 2019年第11期62卷 2038-2051页

作者： wei Yun HUANG wei CAO JinDe BAI WenFei tong ShuZhen National Engineering Laboratory for Green&Safe Construction Technology in Urban Rail Transit Beijing 10037China Beijing Urban Construction Design&Development Group Co. LimitedBeijing 100037China Jiangsu Provincial Key Laboratory of Networked Collective Intelligence ITS Research CenterSoutheast UniversityNanjing 210096China

The basic conception and theoretical system of smart metro are not clear and there is not a unified understanding at the academic *** on this fact,there is no guidance of the smart metro ***,this paper conducts a complete and systemic research on several basic theoretical issues of smart metro,such as the development history,concept,connotation,characteristics,evolution stages,system architecture and main construction ***,the internal and external development demands are analyzed in this *** addition,the subject-cycle-function(SCF)model of smart metro concept is ***,the essential connotation,three typical characteristics and the evolution process of smart metro are ***,the evolution relationships of main function,achievement goal,instrument subject,decision subject,control subject and factor relationship for every evolution stage are ***,according to the theory of system engineering,the three-hierarchy system architecture and five main construction contents are *** both can be used to construct the technical system of smart metro at the academic level,and provide theoretical support and technical guidance for promoting the development of smart metro construction in China.

关键词： smart metro basic theory issues system architecture

Relative phase-dependent two-electron emission dynamics with two-color circularly polarized laser fields

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Chinese Physics B 2020年第9期29卷 281-287页

作者： tong-tong Xu Lian-Lian Zhang Zhao Jin wei-Jiang Gong College of Sciences Northeastern UniversityShenyang 110819China

With the semiclassical ensemble model, we explore the relative phase-dependent nonsequential double ionization (NSDI) of Mg by counter-rotating two-color circularly polarized (TCCP) laser pulses. The yield of Mg2+ sensitively depends on the relative phase Δφ and the intensity of TCCP laser fields. At Δφ=1.5π, the yield of Mg2+ exhibits a pronounced peak in the 0.05 PW/cm2 laser field. This behavior results from the increase of the initial transverse velocity compensating for the drift velocity with the decreasing angle by analyzing the angular distributions of the electron pairs in four relative phases. By changing the relative phases, we find that the recollision excitation with subsequent ionization and the recollision-impact ionization mechanisms can be controlled with TCCP laser fields.

关键词： nonsequential double ionization relative phases two-electron emission dynamics

Research on Stock Price Prediction Method Based on the GAN-LSTM-Attention Model

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Computers, Materials & Continua 2025年第1期82卷 609-625页

作者： Peng Li Yanrui wei Lili Yin College of Computer Science and Technology Harbin University of Science and TechnologyHarbin150006China

Stock price prediction is a typical complex time series prediction problem characterized by dynamics,nonlinearity,and *** paper introduces a generative adversarial network model that incorporates an attention mechanism(GAN-LSTM-Attention)to improve the accuracy of stock price ***,the generator of this model combines the Long and Short-Term Memory Network(LSTM),the Attention Mechanism and,the Fully-Connected Layer,focusing on generating the predicted stock *** discriminator combines the Convolutional Neural Network(CNN)and the Fully-Connected Layer to discriminate between real stock prices and generated stock ***,to evaluate the practical application ability and generalization ability of the GAN-LSTM-Attention model,four representative stocks in the United States of America(USA)stock market,namely,Standard&Poor’s 500 Index stock,Apple Incorporatedstock,AdvancedMicroDevices Incorporatedstock,and Google Incorporated stock were selected for prediction experiments,and the prediction performance was comprehensively evaluated by using the three evaluation metrics,namely,mean absolute error(MAE),root mean square error(RMSE),and coefficient of determination(R2).Finally,the specific effects of the attention mechanism,convolutional layer,and fully-connected layer on the prediction performance of the model are systematically analyzed through ablation *** results of experiment show that the GAN-LSTM-Attention model exhibits excellent performance and robustness in stock price prediction.

关键词： Stock price prediction generative adversarial network attention mechanism time-series prediction