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An explicit method for numerical simulation of wave equations

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Earthquake Engineering and Engineering Vibration 2009年第1期8卷 17-28页

作者： liu heng Liao Zhenpeng Institute of Engineering Mechanics China Earthquake Administration Harbin 150080 China Department of Shipbuilding and Ocean Engineering University of Engineering Harbin 150001 China

In this paper, a method to develop a hierarchy of explicit recursion formulas for numerical simulation in an irregular grid for scalar wave equations is presented and its accuracy is illustrated via 2-D and 1-D models. Approaches to develop the stable formulas which are of 2M-order accuracy in both time and space with Mbeing a positive integer for regular grids are discussed and illustrated by constructing the second order （M= 1） and the fourth order （M = 2） recursion formulas.

关键词： wave equation numerical simulation explicit recursion formula finite element method

Experimental study of vibration mitigation of mast arm signal structures with particle-thrust damping based tuned mass damper

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Earthquake Engineering and Engineering Vibration 2019年第1期18卷 219-231页

作者： Zhang Yunfeng liu heng Dept.of Civil & Environmental Engineering University of Maryland College Park

Large amplitude vibration of mast arm structures due to wind loads are the primary contributing factor to the reduced fatigue life of signal support structures. To alleviate this problem of wind-induced in-plane vibration of mast arm signal structures, a particle-thrust damping based turned mass damper(PTD-TMD) device is adopted and its damping effect is characterized experimentally. The particle-thrust damping is a passive damping device that does not require electric power and is temperature independent. Based on the calibration test, an equivalent dynamic model of the PTD-TMD device is developed and used for numerical simulation study. The damping effects of this PTD-TMD device on signal support structures was investigated through both numerical analysis and laboratory testing of a 50-ft(15.24 m) mast arm structure including both free vibration and forced vibration tests. The experimental test and numerical study results show that vibration response behavior of mast arm signal support structures can be significantly reduced by installing the PTD-TMD that can increase the critical damping ratio of the mast arm signal structures to 4%. The stress range at the welded connection between the mast arm and traffic pole is also reduced.

关键词： fatigue mast arm signal support structures tuned mass damper vibration

An explicit method for numerical simulation of wave equations: 3D wave motion

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Earthquake Engineering and Engineering Vibration 2011年第1期10卷 13-20页

作者： liu heng Liao Zhenpeng Department of Civil Engineering Tsinghua University Beijing 100084 China Institute of Engineering Mechanics China Earthquake Administration Harbin 150080 China Department of Shipbuilding and Ocean Engineering Harbin Engineering University Harbin 150001 China

In this paper, an explicit method is generalized from 1D and 2D models to a 3D model for numerical simulation of wave motion, and the corresponding recursion formulas are developed for 3D irregular grids. For uniform cubic grids, the approach used to establish stable formulas with 2M-order accuracy is discussed in detail, with M being a positive integer, and is illustrated by establishing second order （M=1） recursion formulas. The theoretical results presented in this paper are demonstrated through numerical testing.

关键词： 3D wave equation numerical simulation explicit recursion formula finite element method

Lagrangian description of nonlinear chromatography

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Science China Chemistry 2004年第6期47卷 443-452页

作者： LIANG heng liu Xiaolong The Key Laboratory of Biomedical Information Engineering of Education Ministry Separation Science InstituteXi'an Jiaotong University Xi'an 710049 China The Key Laboratory of Biomedical Information Engineering of Education Ministry Separation Science InstituteXi'an Jiaotong University Xi'an 710049 China

Under the framework of non-equilibrium thermodynamic separation theory (NTST), Local Lagrangian approach (LLA) was proposed to deal with the essential issues of the convec- tion and diffusion (shock waves) phenomena in nonlinear chromatography with recursion equa- tions based on the three basic theorems, Lagrangian description, continuity axiom and local equilibrium assumption (LEA). This approach remarkably distinguished from the system of con- temporary chromatographic theories (Eulerian description-partial differential equations), and can felicitously match modern cybernetics.

关键词： nonlinear chromatography, Lagrangian description, recursion equations, convection-diffusion equations, shock waves.

Bending and vibration of a discontinuous beam with a curvic coupling under different axial forces

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Frontiers of Mechanical Engineering 2020年第3期15卷 417-429页

作者： heng liu Jie HONG Dayi ZHANG School of Energy and Power Engineering Beihang UniversityBeijing 100191China State Key Laboratory of Laser Propulsion and Application Beijing Power Machinery InstituteBeijing 100074China

The transverse stiffness and vibration characteristics of discontinuous beams can significantly differ from those of continuous beams given that an abrupt change in stiffness may occur at the interface of the *** this study,the equations for the deflection curve and vibration frequencies of a simply supported discontinuous beam under axial loads are derived analytically on the basis of boundary,continuity,and deformation compatibility conditions by using equivalent spring *** equation for the deflection curve is solved using undetermined coefficient *** normal function of the transverse vibration equation is obtained by separating *** differential equations for the beam that consider moments of inertia,shearing effects,and gyroscopic moments are investigated using the transfer matrix *** deflection and vibration frequencies of the discontinuous beam are studied under different axial loads and connection spring *** show that deflection decreases and vibration frequencies increase exponentially with increasing connection spring ***,both variables remain steady when connection spring stiffness reaches a considerable ***,an experimental study is conducted to investigate the vibration characteristics of a discontinuous beam with a curvic coupling,and the results exhibit a good match with the proposed model.

关键词： discontinuous beam bending stiffness transverse vibration axial loads gyroscopic moments

Positivity and Stability of Fractional-Order Linear Time-Delay Systems

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Journal of Systems Science & Complexity 2022年第6期35卷 2181-2207页

作者： HAO Yilin HUANG Chengdai CAO Jinde liu heng School of Mathematics and Physics Guangxi University for NationalitiesNanning 530006China School of Mathematics and Statistics Xinyang Normal UniversityXinyang 464000China School of Mathematics Southeast UniversityNanjing 211189China

This article focuses on the positivity and the asymptotic stability of fractional-order linear time-delay systems(FOLTDSs)which are composed of N(N≥2)***,a sufficient and necessary condition is given to ensure the positivity of *** solutions of the studied systems are obtained by using the Laplace transform method,and it can be observed that the positivity of FOLTDSs is completely determined by the series of matrices and independent of the magnitude of ***,a theorem is given to prove the asymptotic stability of positive *** considering the monotonicity and asymptotic properties of systems with constant time-delay,it is further shown that the asymptotic stability of positive FOLTDSs is independent of the ***,a state-feedback controller,whose gain matrix is derived by resolving a linear programming question,is designed such that the state variables of the systems are nonnegative and asymptotically *** the order of the FOLTDSs is greater than one,by utilizing a proposed property of Caputo derivative,a sufficient condition for the positivity of FOLTDS is ***,simulation examples are presented to verify the validity and practicability of the theoretical analysis.

关键词： Asymptotic stability fractional-order system linear programming positivity time-delay

Lanthanide complexes mediated coordinative chain transfer polymerization of conjugated dienes

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Science China(Technological Sciences) 2018年第9期61卷 1286-1294页

作者： WANG Feng liu heng HU YanMing ZHANG XueQuan Key Laboratory of Synthetic Rubber Changchun Institute of Applied Chemistry Chinese Academy of Sciences

Tremendous advances has been witnessed in the past few years in the lanthanide complexes mediated coordinative chain transfer polymerization(CCTP) of conjugated dienes. CCTP features catalyst economy, well-controlling over both microstructure and architecture of the resulting polymers, and accessibility for novel(co)polymers. This review highlights the recent progresses made in the field of CCTP of dienes. After a brief introduction, the body of this review is divided into three parts:(1) principle of CCTP;(2) coordinative chain transfer homopolymerization of dienes;(3) coordinative chain transfer copolymerization of *** the end, we present some challenges remaining in this area and our personal opinion regarding where this field should continue to develop. CCTP represents a novel strategy to prepare polydiene synthetic rubbers with controlled high molecular weight and narrow molecular weight distribution, which has reached the practical industrial application level, demonstrating a great potential in industrialization.

关键词： coordinative chain transfer polymerization dienes lanthanide complexes

Temporal and spatial regulation of biomimetic vascularization in 3D-printed skeletal muscles

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Bio-Design and Manufacturing 2024年第5期7卷 597-610页

作者： Minxuan Jia Tingting Fan Tan Jia Xin liu heng liu Qi Gu Key Laboratory of Organ Regeneration and Reconstruction State Key Laboratory of Membrane BiologyInstitute of ZoologyChinese Academy of SciencesBeijing 100101China Beijing Institute for Stem Cell and Regenerative Medicine Beijing 100101China University of Chinese Academy of Sciences Beijing 100049China State Key Laboratory of Stem Cell and Reproductive Biology Institute of ZoologyChinese Academy of SciencesBeijing 100101China Department of Orthopaedics Beijing Jishuitan HospitalCapital Medical UniversityBeijing 100035China

In the intricate skeletal muscle tissue,the symbiotic relationship between myotubes and their supporting vasculature is pivotal in delivering essential oxygen and *** study explored the complex interplay between skeletal muscle and endothelial cells in the vascularization ofmuscle *** harnessing the capabilities of three-dimensional(3D)bioprinting and modeling,we developed a novel approach involving the co-construction of endothelial and muscle cells,followed by their subsequent *** findings highlight the importance of the interaction dynamics between these two cell ***,introducing endothelial cells during the advanced phases of muscle differentiation enhanced myotube ***,it stimulated the development of the vascular network,paving the way for the early stages of vascularized skeletal muscle *** methodology proposed in this study indicates the potential for constructing large-scale,physiologically aligned skeletal ***,it highlights the need for exploring the delicate equilibrium and mutual interactions between muscle and endothelial *** on the multicell-type interaction model,we can predict promising pathways for constructing even more intricate tissues or organs.

关键词： Skeletal muscle Vascularization 3D bioprinting Cell interaction

Seismic fragility analysis of composite frame structure based on performance

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Earthquake Science 2010年第1期23卷 45-52页

作者： Jingbo liu Yangbing liu heng liu Department ofCivilEngineering Tsinghua University Beo'ing 100084 China College of Civil Engineering Chongqing University Chongqing 400045 China

Steel-concrete composite structures that share the advantages of both steel structure and concrete structure have been developed rapidly and used widely. It has been a popular structure in high-rise buildings in recent years. Although more and more composite structures have been used in earthquake area, only a few literatures about fragility analysis of this type of structure are available. In this paper, a fragility analysis method based on performance is proposed, in which both the uncertainty due to variability in structures and ground motion are considered. Seismic fragility analysis is performed for a 15-story composite beam-concrete-filled square steel tube column frame by the proposed method. The top-drift-angle and the story-drift-angle are used as quantitative indexes to define the four different performance levels. Then seismic demand probability analysis is carried out and fragility curves are derived to assess the seismic performance of this type of structure.

关键词： composite structure performance level seismic demand fragility curve