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Acta Mathematicae Applicatae Sinica 2024年第3期40卷 708-727页

作者： Wei-qi peng Yong CHEN School of Mathematical Sciences East China Normal UniversityShanghai 200241China College of Mathematics and Systems Science Shandong University of Science and TechnologyQingdao 266590China

In this work,we mainly consider the Cauchy problem for the reverse space-time nonlocal Hirota equation with the initial data rapidly decaying in the solitonless *** from the Lax pair,we first construct the basis Riemann-Hilbert problem for the reverse space-time nonlocal Hirota ***,using the approach of Deift-Zhou nonlinear steepest descent,the explicit long-time asymptotics for the reverse space-time nonlocal Hirota is *** the reverse space-time nonlocal Hirota equation,since the symmetries of its scattering matrix are different with the local Hirota equation,the v(λ_(i))(i=0,1)would like to be imaginary,which results in theδ_(λi)^(0)contains an increasing t(±Imv(λ_(i)))/2,and then the asymptotic behavior for nonlocal Hirota equation becomes differently.

关键词： Riemann-Hilbert problem reverse space-time nonlocal Hirota equation long-time asymptotics nonlinear steepest descent method

Typhoon wind hazard model and estimation on return period of typhoon wind speed

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Journal of Oceanology and Limnology 2021年第2期39卷 420-436页

作者： Yunxia GUO Yijun HOU peng qi Key Laboratory of Ocean Circulation and Waves Institute of OceanologyChinese Academy of SciencesQingdao 266071China University of Chinese Academy of Sciences Beijing 100049China Laboratory for Ocean and Climate Dynamics Qingdao National Laboratory for Marine Science and TechnologyQingdao 266237China Center for Ocean Mega-Science Chinese Academy of SciencesQingdao 266071China

Typhoons are one of the most serious natural disasters that occur annually on China’s southeast coast.A technique for analyzing the typhoon wind hazard was developed based on the empirical track model,and used to generate 1000-year virtual typhoons for Northwest Pacific *** influences of typhoon decay model,track model,and the extreme value distribution on the predicted extreme wind speed were *** found that different typhoon decay models have least influence on the predicted extreme wind *** most of the southeast coast of China,the predicted wind speed by the non-simplified empirical track model is larger than that from the simplified tracking *** extreme wind speed predicted by different extreme value distribution is quite *** super typhoons Meranti(2016),Hato(2017),Mangkhut(2018)and Lekima(2019)were selected and the return periods of typhoon wind speeds along the China southeast coast were estimated in order to assess the typhoon wind hazard.

关键词： typhoon empirical track model decay model extreme wind speed return period

l^1-error estimates on the immersed interface upwind scheme for linear convection equations with piecewise constant coefcients: A simple proof

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Science China Mathematics 2013年第12期56卷 2773-2782页

作者： JIN Shi qi peng Department of Mathematics Institute of Natural Sciences and MOE Key Lab in Scientific and Engineering ComputingShanghai Jiao Tong University Department of Mathematics University of Wisconsin-MadisonMadison WI 53706 USA

A linear convection equation with discontinuous coefficients arises in wave propagation through interfaces. An interface condition is needed at the interface to select a unique solution. An upwind scheme that builds this interface condition into its numerical flux is called the immersed interface upwind scheme. An ι1-error estimate of such a scheme was first established by Wen et al. （2008）. In this paper, we provide a simple analysis on the ι1-error estimate. The main idea is to formulate the solution to the underline initial-value problem into the sum of solutions to two convection equations with constant coefficients, which can then be estimated using classical methods for the initial or boundary value problems.

关键词： ι1-error estimates linear convection equation with discontinuous coefficients immersed interphasemethod

Evaluation of Environmental Quality for Abandoned Coal Mine Based on Environmental Vulnerability Index

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Energy Engineering 2021年第3期118卷 727-736页

作者： peng qi Yu Shang School of Law and Humanities China University of Mining&TechnologyBeijing100083China School of Management China University of Mining&TechnologyBeijing100083China

With the increasingly prominent environmental problems of abandoned coal mines,this paper discussed the significance of environmental vulnerability assessment of abandoned coal *** vulnerability assessment is essentially an assessment of environmental *** present,the research object of environmental impact assessment method and program of mine is mostly single ***,the impact of abandoned coal mine on the environment is multifaceted,which was summarized into nine prominent common *** on these nine factors,the environmental vulnerability assessment model of abandoned coal mine based on multifactor evaluation was established by using the analytic hierarchy process(AHP)method,the ranking criteria of nine factor indexes was proposed,the evaluation process was established,and the evaluation index system of environmental vulnerability of abandoned coal mines was *** environmental vulnerability assessment method of abandoned coal mines has universal applicability,which can provide the basis for the government and enterprises to carry out treatment and planning of abandoned coal mine and promote the optimization of governance effect.

关键词： Abandoned coal mine environmental vulnerability analytic hierarchy process

Analysis of typhoon wind hazard in Shenzhen City by Monte-Carlo Simulation

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Journal of Oceanology and Limnology 2019年第6期37卷 1994-2013页

作者： GUO Yunxia HOU Yijun qi peng Key Laboratory of Ocean Circulation and Waves Institute of OceanologyChinese Academy of SciencesQingdao 266071China University of Chinese Academy of Sciences Beijing 100049China Laboratory for Ocean and Climate Dynamics Qingdao National Laboratory for Marine Science and TechnologyQingdao 266237China Center for Ocean Mega-Science Chinese Academy of SciencesQingdao 266071China

As one of the most serious natural disasters,many typhoons affect southeastern China every *** Shenzhen,a coastal city in southeast China as an example,we employed a Monte-Carlo simulation to generate a large number of virtual typhoons for wind hazard *** analyzing 67-year historical typhoons data from 1949 to 2015 using the Best Track Dataset for Tropical Cyclones over the Western North Pacific recorded by the Shanghai Typhoon Institute,China Meteorological Administration(CMASTI),typhoon characteristic parameters were extracted and optimal statistical distributions established for the parameters in relation to *** employed the Monte-Carlo method to sample each distribution to generate the characteristic parameters of virtual *** addition,the Yah Meng(YM)wind field model was introduced,and the sensitivity of the YM model to several parameters *** the YM wind field model,extreme wind speeds were extracted from the virtual *** extreme wind speeds for different return periods were predicted and compared with the current structural code to provide improved wind load information for wind-resistant structural design.

关键词： typhoon hazard analysis Monte-Carlo simulation wind field model extreme wind speed

Science Letters:A current-differential-based method for improving dynamic characteristics of electromagnetic actuators

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第9期10卷 1241-1244页

作者： Ping FANG qi-peng LI Fan DING State Key Lab of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China School of Mechanical and Automotive Engineering Zhejiang University of Science and Technology Hangzhou 310023 China

This paper presents a new control strategy based on current differential feedback to accelerate the dynamic response of electromagnetic actuators, instead of traditional closed-loop control based on displacement feedback. The method mainly includes a differentiator, proportioner and signal synthesizer. Analysis and simulation on the step characteristics of an electromagnetic actuator were discussed, and all the results show that the approach can improve the actuator's step response greatly. Finally, the control method is applied to a real gravure system which verifies the control performance.

关键词： Electromagnetic actuator Control method Dynamic characteristics Current differential

Visualization Investigation on Flowing Condensation in Horizontal Small Channels with Liquid Separator

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Journal of Thermal Science 2018年第1期27卷 48-54页

作者： ZHANG Xuan JIA Li DANG Chao peng qi Institude of Thermal Engineering School of MechanicalElectronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China Beijing key laboratory of flow and heat transfer of phase changing in micro and small scale Beijing 100044China

A simultaneous visualization and measurement experiment was carried out to investigate condensation flow pat- terns and condensing heat transfer characteristics of refrigerant R14 lb in parallel horizontal multi-channels with liquid-vapor separator. The hydraulic diameter of each channel was 1.5 mm and the channel length was 100 ram. The refrigerant vapor flowing in the small channels was cooled by cooling water. The parallel horizontal mul- ti-channels were covered with a transparent silica glass for visualization of flow patterns. Experiments were per- formed at different inlet superheat temperatures （ranging from 3~C to 7~C）. Mass velocity was in the range of 82.37 kg mZs1 to 35.56 kg m-2s1. It was found that there were three different flow patterns through the mul- ti-channels with the increase of mass velocity. The flow patterns in each channel pass almost tended to be same and all of them were annular flows.＇ The efficiency of the liquid-vapor separator with U-type was related to vapor mass velocity and the pressure in the small channels. It was also found that the heat transfer coefficient increased with the increase of the mass velocity while the cooling water mass flow rate increased. It increased to a top point and then decreased. It increased with the increase of superheat in the low superheat temperature region.

关键词： condensation visualization multi-channels liquid-vapor separation

A New Flexible Multibody Dynamics Analysis Methodology of Deployable Structures with Scissor-Like Elements

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Chinese Journal of Mechanical Engineering 2019年第5期32卷 107-116页

作者： qi’an peng Sanmin Wang Changjian Zhi Bo Li School of Mechanical Engineering Northwestern Polytechnical University

There are vast constraint equations in conventional dynamics analysis of deployable structures,which lead to differential-algebraic equations(DAEs)solved *** reduce the difficulty of solving and the amount of equations,a new flexible multibody dynamics analysis methodology of deployable structures with scissor-like elements(SLEs)is ***,a precise model of a flexible bar of SLE is established by the higher order shear deformable beam element based on the absolute nodal coordinate formulation(ANCF),and the master/slave freedom method is used to obtain the dynamics equations of SLEs without constraint ***,according to features of deployable structures,the specification matrix method(SMM)is proposed to eliminate the constraint equations among SLEs in the frame of *** this method,the inner and the boundary nodal coordinates of element characteristic matrices can be separated simply and efficiently,especially on condition that there are vast nodal *** the element characteristic matrices can be added end to end ***,the dynamic model of deployable structure reduces dimension and can be assembled without any constraint ***,a new iteration procedure for the generalized-a algorithm is presented to solve the ordinary differential equations(ODEs)of deployable ***,the proposed methodology is used to analyze the flexible multi-body dynamics of a planar linear array deployable structure based on three scissor-like *** simulation results show that flexibility has a significant influence on the deployment motion of the deployable *** proposed methodology indeed reduce the difficulty of solving and the amount of equations by eliminating redundant degrees of freedom and the constraint equations in scissor-like elements and among scissor-like elements.

关键词： Flexible multibody dynamics Scissor-like elements Absolute nodal coordinate formulation Specification matrix method Ordinary differential equations

The Effect of Heating Direction on Flow Boiling Heat Transfer of R134a in Microchannels

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Journal of Thermal Science 2017年第2期26卷 166-174页

作者： XU Mingchen JIA Li DANG Chao peng qi Institute of Thermal Engineering School of MechanicalElectronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China Beijing Key Laboratory of Flow and Heat Transfer of Phase Changing in Micro and Small Scale Beijing 100044China

This paper presents effects of heating directions on heat transfer performance of R134 a flow boiling in micro-channel heat sink. The heat sink has 30 parallel rectangular channels with cross-sectional dimensions of 500mm width 500mm depth and 30 mm length. The experimental operation condition ranges of the heat flux and the mass flux were 13.48 to 82.25 W/cm^2 and 373.3 to 1244.4 kg/m^2 s respectively. The vapor quality ranged from 0.07 to 0.93. The heat transfer coefficients of top heating and bottom heating both were up to 25 k W/m^2 K. Two dominate transfer mechanisms of nucleate boiling and convection boiling were observed according to boiling curves. The experimental results indicated that the heat transfer coefficient of bottom heating was 13.9% higher than top heating in low heat flux, while in high heat flux, the heat transfer coefficient of bottom heating was 9.9%.higher than the top heating, because bubbles were harder to divorce the heating wall. And a modified correlation was provided to predict heat transfer of top heating.

关键词： top heating bottom heating flow boiling micro-channels R134a correlation

Analyzing the capability of a radio telescope in a bistatic space debris observation system

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Research in Astronomy and Astrophysics 2013年第12期13卷 1518-1526页

作者： Zhe Zhao You Zhao peng-qi Gao National Astronomical Observatories Chinese Academy of Sciences University of Chinese Academy of Sciences

A bistatic space debris observation system using a radio telescope as the receiving part is introduced. The detection capability of the system at different working frequencies is analyzed based on real instruments. The detection range of targets with a fixed radar cross section and the detection ability of small space debris at a fixed range are discussed. The simulations of this particular observation system at different transmitting powers are also implemented and the detection capability is discussed. The simulated results approximately match the actual experiments. The analysis in this paper provides a theoretical basis for developing a space debris observation system that can be built in China.

关键词： instrumentation: detectors - large radio telescope techniques: radarastronomy