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Stationary patterns in a discrete bistable reaction-diffusion system:mode analysis

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Chinese Physics B 2010年第10期19卷 174-183页

作者：邹为占萌 Wuhan Institute of Physics and Mathematics the Chinese Academy of Sciences Graduate School of the Chinese Academy of Sciences

This paper theoretically analyses and studies stationary patterns in diffusively coupled bistable elements. Since these stationary patterns consist of two types of stationary mode structure： kink and pulse, a mode analysis method is proposed to approximate the solutions of these localized basic modes and to analyse their stabilities. Using this method, it reconstructs the whole stationary patterns. The cellular mode structures （kink and pulse） in bistable media fundamentally differ from stationary patterns in monostable media showing spatial periodicity induced by a diffusive Taring bifurcation.

关键词： discrete reaction-diffusion system stationary patterns bistable mode analysis

Numerical analysis for impacts of nozzle end-clearances on aerodynamic performance and forced response in a VNT turbine

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Chinese Journal of Aeronautics 2018年第5期31卷 1030-1040页

作者： Ben ZHAO Leilei WANG Hongjun HOU Michigan State University East Lansing 48824 USA Hebei University of Engineering Handan 056038 China

It has been well known that nozzle end-clearances in a Variable Nozzle Turbine（VNT）are unfavorable for aerodynamic performance, especially at small openings, and efforts to further decrease size of the clearances are very hard due to thermal expansion. In this paper, both the different sizes of nozzle end-clearances and the various ratios of their distribution at the hub and shroud sides were modelled and investigated by performing 3D Computational Fluid Dynamics（CFD） and Finite Element analysis（FEA） simulations with a code of transferring the aerodynamic pressure from the CFD results to the FEA calculations. It was found that increasing the size of the nozzle end-clearances divided equally at the hub and shroud sides deteriorates turbine efficiency and turbine wheel reliability, yet increases turbine flow capacity. And, when the total nozzle endclearances remain the same, varying nozzle end-clearances＇ distribution at the hub and shroud sides not only shifts operation point of a VNT turbine, but also affects the turbine wheel vibration stress.Compared with nozzle hub clearance, the shroud clearance is more sensitive to both aerodynamic performance and reliability of a VNT turbine. Consequently, a possibility is put forward to improve VNT turbine efficiency meanwhile decrease vibration stress by optimizing nozzle end-clearances＇ distribution.

关键词： Clearance Forced response mode analysis Performance Reliability Variable Nozzle Turbine（VNT）

Flapping dynamics of a flexible propulsor near ground

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Acta Mechanica Sinica 2016年第6期32卷 991-1000页

作者： Jaeha Ryu Sung Goon Park Boyoung Kim Hyung Jin Sung Department of Mechanical Engineering Korea Advanced Institute of Science and Technology

The flapping motion of a flexible propulsor near the ground was simulated using the immersed boundary method. The hydrodynamic benefits of the propulsor near the ground were explored by varying the heaving frequency (St) of the leading edge of the flexible propulsor. Propulsion near the ground had some advantages in generating thrust and propelling faster than propulsion away from the ground. The mode analysis and flapping amplitude along the Lagrangian coordinate were examined to analyze the kinematics as a function of the ground proximity (d) and St. The trailing edge amplitude (\(a_\mathrm{tail}\)) and the net thrust (\(\overline{{F}}_x\)) were influenced by St of the flexible propulsor. The vortical structures in the wake were analyzed for different flapping conditions.

关键词： Flexible propulsor Ground effect Immersed boundary method mode analysis

VIBRATION analysis OF A BEAM WITH EMBEDDED SHAPE MEMORY ALLOY WIRES

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Acta Mechanica Solida Sinica 2013年第5期26卷 536-550页

作者： Mohammad Mehdi Barzegari Morteza Dardel Alireza Fathi Department of Mechanical Engineering Babol University of Technology

In this study, analytical relations for evaluating the exact solution of natural fre- quency and mode shape of beams with embedded shape memory alloy （SMA） wires are presented. Beams are modeled according to Euler-Bernoulli, Timoshenko and third order beam （Reddy） the- ories. A relation is obtained for determining the effect of axial load generated by the recovery action of pre-strained SMA wires. By defining some dimensionless quantities~ the effect of different me- chanical properties on the frequencies and mode shapes of the system are carefully examined. The effect of axial load generated by SMA wires with buckling load and frequency jump is accurately studied.

关键词： shape memory alloy natural frequency mode analysis frequency jump Euler-Bernoulli Timoshenko third order beam buckling

Software for Acoustic Design

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Journal of Applied Mathematics and Physics 2023年第8期11卷 2515-2522页

作者： Anatoliy Sergeevich Suvorov Oleg Fedorovich Sevriukov Evgeniy Mikhailovich Sokov Mikhail Borisovich Salin Svetlana Georgievna Zaitseva Varvara Alekseevna Sharagina Federal Research Center A.V. Gaponov-Grekhov Institute of Applied Physics of the Russian Academy of Sciences (IAP RAS) Nizhny Novgorod Russia

We present the СATEС software, which implements the solution to the problems of computational acoustics. The software is based on the use of the superelement method and finite element modeling algorithms, in-cluding... 详细信息

关键词： Software Acoustic Design Acoustic Radiation Superelement Method Fini-te Element Methods Absorbing Boundary Conditions Hydrodynamic Noi-se mode analysis

3D-Simulations of Transverse Optical modes of the Free Electron Laser Resonator with Hole Output Coupling

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Communications in Computational Physics 2006年第5期1卷 920-929页

作者： Yu-Huan Dou Xiao-Jian Shu Yuan-Zhang Wang Institute of Applied Physics and Computational Mathematics P.O.Box 8009Beijing 100088P.R.China

The transverse construction of optical modes in the wiggler is calculated and the numerical simulations of the free-electron laser hole-coupled resonator are carried out.These 3D-simulations include optical amplitude distributions,modes evolvement of optical field and the influence of hole-radius on the distributing of modes.The nu-merical simulations confirm that the fraction of the even-order modes increase in the start-up stage and then decreases in the exponential gain stage.Moreover,it is found that the fundamental mode is dominant in the saturate stage.Based on this observa-tion,we estimate the optical output coupling by using the the fundamental mode.It is found that the numerical results and the first-order estimate are in good agreement for a range of the hole size.

关键词： Free-electron laser optical resonator mode analysis numerical simulation

Second Approximation model for Optical Head in Super High Density Storage Technology

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Wuhan University Journal of Natural Sciences 2000年第2期5卷 155-158页

作者： Wu Wan Pei Xian-deng College of Computer Science and Technology Huazhong University of Science and Technology Wuhan 430074 China

The paper presents second approximation model for optical head in super high-density storage technology firstly and it is an important part for three grades approximate model of ultra-small-size quantum well corn-shaped laser and simulative calculations. It supplies the important and useful results for the NFOD optical head design with ultra thin active layer and ultra small spot laser.

关键词： near field optical disc corn-shaped laser multilayer quantum well mode analysis

Modal analysis of Battery Box Based on ANSYS

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World Journal of Engineering and Technology 2016年第2期4卷 290-295页

作者： Jianong Wang Xiaoyu Zhao College of Automotive Engineering Shanghai University of Engineering and Science Shanghai china

At present, the development of the traditional car is more and more troubled by the high cost of environmental pollution and oil prices, many countries have paid increasingly attention to the research and development of electric vehicles. And vehicle battery box, as the heart of the automobile power system, and many difficulties still exist in its research and development. This paper is based on ANSYS. By using the finite element theory, it is to analyze the modal characteristics of the battery box and frequency vibration characteristics. Having a more comprehensive grasp of the dynamic performance of the battery box is the key to solve the new energy automotive research and development of issues.

关键词： New Energy Battery Box Finite Element Theory mode analysis

Structural Damage Detection with Damage InductionVector and Best Achievable Vector

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Advances in Manufacturing 1997年第3期1卷 214-220页

作者：赵琪周哲玮

This paper presents a new method using the damage induction vector (DIV) and the best achievable vector (BAV) by which the change of modes due to structural damage can be applied to detcrnlinc the location and scale of damage in structures. By the DIV, undamagc elements can be castly identified and the damage detection can be limited to a few domains of the structure. The structural damage is located by conlputing the Euclidean distance betwcen the DIV and its BAV. The loss of both stiffness and mass properties can be located and quantified.The characteristic of this method is less calculation and there is no limitation of damage scale. Finally, the effectiveness of the method is demonstrated by detecting the damages of the shallow arches.

关键词： structural damage detection mode analysis damage induction vector best achievablc vector