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Higher-mode effect on the seismic responses of buildings with viscoelastic dampers

Earthquake Engineering and Engineering Vibration 2002年第1期1卷 119-129页

作者： Meng-Hao Tsai Department of Civil Engineering Taiwan UniversityChinese Taipei Postdoctoral Research Fellow

In conventional modal analysis procedures,usually only a few dominant modes are required to describe the dynamic behavior of multi-degrees-of-freedom *** number of modes needed in the dynamic analysis depends on the higher-mode contribution to the structural response,which is called the higher-mode *** modal analysis approach, however,may not be directly applied to the dynamic analysis of viscoelastically damped *** is because the dynamic properties of the viscoelastic dampers depend on their vibration ***,the structural stiffness and damping contributed from those dampers would be different for each *** this study,the higher-mode effect is referred to as the response difference induced by the frequency-dependent property of viscoelastic dampers at higher *** analysis procedures for buildings with viscoelastic dampers distributed proportionally and non-proportionally to the stiffness of the buildings are developed to consider the higher-mode *** studies on shear-type viscoelastically damped building models are conducted to examine the accuracy of the proposed procedures and to investigate the significance of the higher-mode effect on their seismic *** damper models are used to estimate the peak damper forces in the proposed procedures. Study results reveal that the higher-mode effect is significant for long-period viscoelastically damped *** higher-mode effect on base shear is less significant than on story acceleration *** difference of the seismic response usually occurs at the top ***,the higher-mode effect may not be reduced by decreasing the damping ratio provided by the viscoelastic *** practical application,it is realized that the linear viscous damping model without considering the higher-mode effect may predict larger damper forces and hence,is on the conservative side.

关键词： model analysis viscoelastic dampers higher-mode effect

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Velocity Profiles between Two Baffles in a Shell and Tube Heat Exchanger

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Journal of Thermal Science 2015年第4期24卷 356-363页

作者： Tae-Hyun Chang Chang-Hoan Lee Hae-Soo Lee Kwon-Soo Lee Senior research fellow of RESEAT Korea Institute of Science and Technology Information Korea Institute of Science and Technology Information postdoctoral research fellow School of Mechanical Engineering of Kyungnam University International University of Korea

Heat exchangers are extensively utilized for waste heat recovery,oil refining,chemical processing,and steam *** this study,velocity profiles are measured using a 3D particle image velocimetry(PIV)system between two baffles in a shell and tube heat exchanger for parallel and counter *** PIV and computational fluid dynamics results show the occurrence of some strong vectors near the *** vectors are assumed due to the clearance between the inner tubes and the front ***,the major parts of the vectors are moved out through the bottom opening of the rear baffle,and other vectors produce a large circle between the two *** simulations are conducted to investigate the effects of the baffle on the heat exchanger using the Fluent *** k-εturbulence model is employed to calculate the flows along the heat exchanger.

关键词： Baffle P1V Shell and tube heat exchanger Cut off ratio CFD

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Effect of Cambering on the Aerodynamic Performance of Heaving Airfoils

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Journal of Bionic Engineering 2009年第4期6卷 398-404,406-407页

作者： Joel E.Guerrero postdoctoral research fellow Department of CivilEnvironmental and Architectural EngineeringUniversity of GenoaVia Montallegro 1Genoa16145Italy

In the present work,a parametric numerical study is conducted in order to assess the effect of airfoil cambering on the aerodynamic performance of rigid heaving *** incompressible Navier-Stokes equations are solved in their velocity-pressure formulation using a second-order accurate in space and time finite-difference *** tackle the problem of moving boundaries,the governing equations are solved on overlapping structured *** numerical simulations are performed at a Reynolds number of Re=1100 and at different values of Strouhal number and reduced *** results obtained show that the airfoil cambering geometric parameter has a strong influence on the average lift coefficient,while it has a smaller impact on the average thrust coefficient and propulsive efficiency of heaving airfoils.

关键词： heaving airfoils structured overlapping grids incompressible Navier-Stokes equations airfoil cambering

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Velocity Profiles between Two Baffles in a Horizontal Circular Tube

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Journal of Thermal Science 2014年第6期23卷 544-551页

作者： Tae-Hyun Chang Hae-Soo Lee Keon-Je Oh Doeg Hee Doh Chang-Hoan Lee Senior research fellow of RESEAT Korea Institute of Science and Information postdoctoral research fellow School of Mechanical Engineering of Kyungnam University School of Mechanical Engineering Kyungnam University Division of Mechanical and Energy Systems Engineering Korea Marine and Ocean University Korea Institute of Science and Technology Information

The shell and tube heat exchanger is an essential part of a power plant for recovering heat transfer between the feed water of a boiler and the wasted *** baffles are also an important element inside the heat *** materials influence the flow pattern in the *** influence of baffles in the velocity profiles was observed using a three-dimensional particle image velocimetry around baffles in a horizontal circular *** velocity of the particles was measured before the baffle and between them in the test *** show that the flows near the front baffle flow were parallel to the vertical wall,and then concentrate on the upper opening of the front *** flows circulate in the front and rear *** flow profiles are related to the Reynolds number(Re) or the flow *** velocity profiles at lower Re number showed a complicated mixing,concentrating on the lower opening of the rear baffle as front *** flow was employed in this study,which was produced using tangential velocities at the *** the entrance of the front baffle,the velocity vector profiles with swirl were much different from that without ***,velocities between two baffles are not much different from those without swirl.

关键词： Baffle Shell and tube Tangential inlet Swirl Particle image velocimetry

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Impurity Deionization Effects on Surface Recombination DC Current-Voltage Characteristics in MOS Transistors

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Journal of Semiconductors 2010年第12期31卷 1-10页

作者：陈祖辉揭斌斌薩支唐 Lee-Kuan-Yew postdoctoral fellow 2007-2010Nanyang Technological University Department of Physics Xiamen University CTSAH Associates Gainesville

Impurity deionization on the direct-current current-voltage characteristics from electron-hole recombi- nation （R-DCIV） at SiO2/Si interface traps in MOS transistors is analyzed using the steady-state Shockley-Read-Hall recombination kinetics and the Fermi distributions for electrons and holes. Insignificant distortion is observed over 90% of the bell-shaped R-DCIV curves centered at their peaks when impurity deionization is excluded in the theory. This is due to negligible impurity deionization because of the much lower electron and hole concentrations at the interface than the impurity concentration in the 90% range.

关键词： recombination current impurity deionization interface traps MOS transistors

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INVERSION OF MULTILAYERED VARIABLE DENSITY MODELS AND STUDY OF CRUSTAL AND UPPER MANTLE STRUCTURE

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Science China Chemistry 1990年第8期33卷 1002-1013页

作者：陈胜早 Instisute of Geophysics State Seismological Bureau Beijing 100083 PRC Postdoctoral fellow in Canadian Government Laboratory Ontario Canada.

This paper presents a direct gravity inverse method of multilayered variable density models, and gives gravity forward formulae under various conditions of density-depth functions such as the constant, exponential, linear, sine and cosine, cubic spline, and Fourier progression. The testing of theoretical models and the analysis of real examples have been made for the cubic spline function and have proved that the method is effective. Other formulae can be applied under corresponding conditions by means of optimization or other methods.

关键词： multilayered variable density gravity forward and inverse problems crustal and upper mantle structure optimization

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Perturbation of the Moore–Penrose Metric Generalized Inverse in Reflexive Strictly Convex Banach Spaces

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Acta Mathematica Sinica,English Series 2016年第6期32卷 725-735页

作者： Jian Bing CAO Wan Qin ZHANG postdoctoral research Base He'nan Institute of Science and Technology postdoctoral research Station of Physics He'nan Normal University Department of Mathematics He'nan Institute of Science and Technology

Let X, Y be reflexive strictly convex Banach spaces, let T, δT ： X → Y be bounded linear operators with closed range R（T）. Put T= T ＋ δT. In this paper, by using the concept of quasiadditivity and the so called generalized Neumman lemma, we will give some error estimates of the bounds of ｜｜T^M｜｜. By using a relation between the concepts of the reduced minimum module and the gap of two subspaces, some new existence characterization of the Moore-Penrose metric generalized inverse T^M of the perturbed operator T will be also given.

关键词： Metric generalized inverse perturbation reflexive strictly convex Banach space

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Two-Level Linear Relaxation Method for Generalized Linear Fractional Programming

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Journal of the Operations research Society of China 2023年第3期11卷 569-594页

作者： Hong-Wei Jiao You-Lin Shang postdoctoral research Base Henan Institute of Science and TechnologyXinxiang453003HenanChina postdoctoral research Station of Control Science and Engineering Henan University of Science and TechnologyLuoyang471023HenanChina

This paper presents an efficient algorithm for globally solving a generalized linear fractional programming *** establishing this algorithm,we firstly construct a two-level linear relaxation method,and by utilizing the method,we can convert the initial generalized linear fractional programming problem and its subproblems into a series of linear programming relaxation *** on the branch-and-bound framework and linear programming relaxation problems,a branch-and-bound algorithm is presented for globally solving the generalized linear fractional programming problem,and the computational complexity of the algorithm is ***,numerical experimental results demonstrate the feasibility and efficiency of the proposed algorithm.

关键词： Generalized linear fractional programming Global optimization Two-level linear relaxation method Branch-and-bound

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Reliability Study on the Risk Precontrol Management System of Coal Mines Safety

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Journal of Donghua University(English Edition) 2014年第6期31卷 886-889页

作者：孙青 postdoctoral Work Station Shenhua G roup Corporation Limited postdoctoral Mobile research Station China University of Mining and Technology

Risk precontrol management system of coal mines safety( RPMSCS) provides a set of preventive safety management strategy for high-risk coal industries, which has captured extensive attentions. Fundamentally,there are several membership systems with subsystems in the management system, and the subsystem reliability has an important influence on the management system performance. Through analyzing the structure characteristics of the management system,the phase type distribution was employed to analyze its subsystem reliability by considering repair process and three states including working,fail-abnormal,and fail-emergency states. The reliability indices of the subsystem were derived respectively,including the probabilities that the subsystem in three states,mean time to the first failure, mean time to first failemergency,mean working time to first fail-emergency,and mean maintenance time to the first fail-emergency, are derived respectively. The probabilities of the membership systems and the management system in three states were also derived. Some numerical examples were used to show the procedures. The result is important for better understanding the management system operation and improving its operational performance from the respect of system reliability.

关键词： safety management risk precontrol management system system modeling phase type distribution system reliability

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Study on the influences of ionization region material arrangement on Hall thruster channel discharge characteristics

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Plasma Science and Technology 2018年第2期20卷 47-55页

作者：胡翔段萍宋继磊李文庆陈龙边兴宇 College of Science Dalian Maritime University Transportation Engineering postdoctoral research Station Dalian Maritime University

There exists strong interaction between the plasma and channel wall in the Hall thruster,which greatly affects the discharge performance of the *** this paper,a two-dimensional physical model is established based on the actual size of an Aton P70 Hall thruster discharge *** particle-in-cell simulation method is applied to study the influences of segmented low emissive graphite electrode biased with anode voltage on the discharge characteristics of the Hall thruster *** influences of segmented electrode placed at the ionization region on electric potential,ion number density,electron temperature,ionization rate,discharge current and specific impulse are *** results show that,when segmented electrode is placed at the ionization region,the axial length of the acceleration region is shortened,the equipotential lines tend to be vertical with wall at the acceleration region,thus radial velocity of ions is reduced along with the wall *** axial position of the maximal electron temperature moves towards the exit with the expansion of ionization ***,the electron-wall collision frequency and ionization rate also increase,the discharge current decreases and the specific impulse of the Hall thruster is slightly enhanced.

关键词： Hall thruster segmented electrode particle-in-cell wall material

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