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Acta Mechanica Sinica 2012年第5期28卷 1436-1448页

作者： z.-K.Peng z.-q.lang G.Meng S.A.Billings State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University Department of Automatic Control and Systems Engineering University of Sheffield

In the present study, the Volterra series theory is adopted to theoretically investigate the force transmissibility of multiple degrees of freedom （MDOF） structures, in which an isolator with nonlinear anti-symmetric viscous damping is assembled. The results reveal that the anti-symmetric nonlinear viscous damping can significantly reduce the force trans- missibility over all resonance regions for MDOF structures with little effect on the transmissibility over non-resonant and isolation regions. The results indicate that the vibration isolators with an anti-symmetric damping characteristic have great potential to solve the dilemma occurring in the design of linear viscously damped vibration isolators where an increase of the damping level reduces the force transmissibility over resonant frequencies but increases the transmissibility over non-resonant frequency regions. This work is an extension of a previous study in which MDOF structures installed on the mount through an isolator with cubic nonlinear damping are considered. The theoretical analysis results are also verified by simulation studies.

关键词： Nonlinear viscous damping Force transmissibility - Vibration isolation Volterra series

Analysis of vibration reduction level in an 8/6 switched reluctance machine by active vibration cancellation

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Journal of z.ejiang University-Science C(Computers and Electronics) 2010年第10期11卷 808-816页

作者： Xu LIU z.i-ping PAN z. q. z.U School of Electrical Engineering Zhejiang University Hangzhou 310027 China Department of Electronic and Electrwal Engmeermg University of Sheffield Sheffield S1 3JD UK

This paper proposes an analytical model for predicting the maximum vibration reduction level in a four-phase 8/6 switched reluctance machine(SRM) by employing active vibration cancellation(AVC),one of the most effective and convenient methods for reducing the vibration and acoustic noise produced by *** on the proposed method,the factors that influence the vibration reduction level are analyz.d in *** relationships between vibration and noise reduction levels at resonance frequency and rotor speed are ***,it is shown that a large damping factor will lead to smaller vibration reduction level with AVC while,in contrast,a large resonance frequency will increase the vibration reduction *** finite element analyses and experiments were carried out on a prototype 8/6 SRM to validate the proposed method.

关键词： Active vibration cancellation Analytical model Switched reluctance machine Vibration

EXPERIMENTAL RESEARCH AND NUMERICAL SIMULATION OF LASER SHOCK FORMING OF TA2 TITANIUM SHEET

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Acta Metallurgica Sinica(English Letters) 2006年第5期19卷 347-354页

作者： F. Wang z. q. Yao J. Hu q.L. Deng School of Mechanical Engineering Shanghai Jiao Tong UniversityShanghai 200030 China

Laser shock forming （ISF） was a new technique realiz.d by applying an impulsive pressure generated by laser-induced shock wave on the surface of metal sheet. LSF of metal sheet was investigated with experiments and numerical simulation. The basic theories were introduced; the surface quality and deformation of the processed titanium sample （TA2） were examined; ABAqUS was used to simulate ISF and the central displacement of the shocked region was measured and compared with the simulation. Overlapped ISF treatment was experimentally carried out to produce groove and simulation. The results showed that the surface quality and the microstructure with single laser pulse had no remarkable change, and ablation was observed on the surface of the sample with overlapped pulses. The deformation observed in the numerical simulation agreeed with that observed in the experimental measurement quite well.

关键词： laser shock forming numerical simulation surface quality deformation

State estimation over a communication network:measurement or estimate communication?

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控制理论与应用（英文版） 2010年第1期8卷 20-26页

作者： Ling SHI Ye YUAN Michael z. q. CHEN Electronic and Computer Engineering Hong Kong University of Science and Technology Hong Kong China Control Group Department of Engineering University of Cambridge Cambridge CB2 IPZ UK Department of Automation Nanjing University of Science and Technology Nanjing Jiangsu 210094 China)

In this paper we consider the problem of state estimation over a communication network. Using estimation quality as a metric, two communication schemes are studied and compared. In scheme one, each sensor node communicates its measurement data to the remote estimator, while in scheme two, each sensor node communicates its local state estimate to the remote estimator. We show that with perfect communication link, if the sensor has unlimited computation capability, the two schemes produce the same estimate at the estimator, and if the sensor has limited computation capability, scheme one is always better than scheme two. On the other hand, when data packet drops occur over the communication link, we show that if the sensor has unlimited computation capability, scheme two always outperforms scheme one, and if the sensor has limited computation capability, we show that in general there exists a critical packet arrival rate, above which scheme one outperforms scheme two. Simulations are provided to demonstrate the two schemes under various circumstances.

关键词： Networked estimation Kalman filtering Packet-dropping network

STUDY OF THE INFLUENCE OF pH ON THE ELECTROCRYSTALLIz.TION OF z.NC

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Acta Metallurgica Sinica(English Letters) 2005年第4期18卷 497-504页

作者： z. z.ang W.H. Leng J. q. z.ang Department of Chemistry Zhejiang University Hangzhou 310027 China State Key Laboratory for Corrosion and Protection Institute of Metal Reseach The Chinese Academy of Sciences Shenyang 110016 China

The influence of pH value of the electrolyte solution on the z.nc electroplating process was studied by means of cyclic voltammetry and chronoamperometry approaches. The results shown that, under this experimental conditions and at high overpotentials, the nucleation of z.nc is instantaneous, and the nuclear densities N increase with the overpotentials. While at low potentials, no distinguished nucleation current can be observed. High pH promotes the deposition either by drifting the initial depositing potential positively, or by increasing the depositing current through the change of the total charge of the adsorption process qads, i.e., thevstructure of electrochemical double layer.

关键词： z.nc electroplating nucleation growth mechanism

MORPHOLOGY OF AMORPHOUS SILICA DURING ALUMINUM REACTIVE PENETRATION

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Acta Metallurgica Sinica(English Letters) 2000年第4期13卷 944-948页

作者： z.ou, z. Gan, q.S. Ding, P.D. Chongqing Univ Chongqing China

The reduction of volume of silica glass during aluminum reactive penetration was observed experimentally. The liquid aluminum infiltrates easily into the cavities while the released silicon is solved in the liquid aluminum, and Al/Al2O3 composites could be obtained. The experimental results show that Al/Al2O3 composites can be transformed into Al2O3 grains by oxygen in the cavities of Al/Al2O3 composites during the longer penetration treatment. The formation of alumina is a sintering process, in which liquid aluminum, particulate alumina and oxygen play an important role. The transformtion process has shown that there is a relationship of σAl2O3-Al2O3 2O3-Al, where σAl2O3-Al2O3 is the grain boundary energy of alumina, and σAl2O3-Al is the interface energy between aluminum and alumina. The formation temperature by aluminum reactive penetration is much lower than that by sintering.

关键词： Alumina Aluminum Metallic matrix composites Morphology Silica

SYNTHESIS AND IDENTIFICATION OF CONDUCTING POLYANILINE DOPED WITH RARE EARTH CHLORIDE

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Acta Metallurgica Sinica(English Letters) 2000年第3期13卷 872-876页

作者： Yang, C.M. z.ang, q.R. Fang, z. Central South Univ of Technology Changsha China

Polyaniline doped with rare earth chloride was synthesiz.d in organic solvent and identified by elemental analysis and infrared spectroscopy. The experimental results show that there exists both doping and complexation at the same time in the resulting product. When pH4. Moreover, polyaniline doped with rare earth chloride exhibits better thermal stability than that doped with hydrochloric acid.

关键词： Chlorine compounds Composition Conductive materials Electric conductivity Organic polymers Rare earth compounds Synthesis (chemical)

A Modified Entropy Generation Number for Heat Exchangers

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Journal of Thermal Science 1996年第4期5卷 257-263页

作者： z. M. Xu S. R. Yang z. q. Chen Department of Power Engineering Northeast China Institute of Electric Power Engineering Jilin City China Energy and Power Machinery Engineering Institute Xi’an Jiaotong University Xi’an China

This paper demonstrates the difference between the entropy generation number method proposed by Bejan and the method of entropy generation per unit amount of heat transferred in analyz.ng the thermodynamic performance of heat exchangers, points out the reason for leading to the above difference.A modified entropy generation number for evaluating the irreversibility of heat exchangers is proposed which is in consistent with the entropy generation per unit amount of heat transferred in entropy generation analysis. The entropy generated by friction is also investigated. Results show that when the entropy generated by friction in heat exchangers is taken into account, there is a minimum total entropy generation number while the NTU and the ratio of heat capacity rates vary. The existence of this minimum is the prerequisite of heat exchanger optindz.tion.

关键词： entropy generation heat exchanger.

KINETIC STUDY OF SPINEL LiMn_2O_4 SYNTHESIz.D BY SOLID REACTION WITH SOFT-CHEMICAL METHOD

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Acta Metallurgica Sinica(English Letters) 2005年第4期18卷 512-518页

作者： C.q. Xu Y. W. Tian Y. C. z.ai z.J. Guo z. q. Huang School of Materials and Metallurgy Northeastern University Shenyang 110004 China

The differential thermal analysis （DTA） curves were measured at different heating rates in flowing air for studying the synthesis of the spinel LiMn2O3 with Li2CO3 and MnO2, The reaction began at about 503K, and finished at about 873K. The apparent activation energy of Kissinger method was about ***^-1, the reaction orderwas 1.67, the frequency factor was 7.81×10^9, and therefore the dinetic epuation was dδ/dt=A·exp（- E/RT）·（1-δ）^n=7.81×10^9, exp（-122770/RT）·（l-δ）^1.67 . Coats-Redfem integral method was used to analyz. the DTA curves of the samples at different heating rates, and the calculated apparent activation energy and frequency factor were 112. 13kJ· mol^-1 and 1.18 × 10^9, respectively, rather close to that of Kissinger method. X-ray diffraction （XRD） and scanning electron microscope （SEM） results shown that the synthesiz.d LiMn2O3 possesses pure phase, regular shape and normal particle distribution.

关键词： lithium manganese oxides synthesiz.d kinetics Kissinger method,Coats-Redfern integral method

DEFORMATION BEHAVIOR OF AA6063 ALUMINIUM ALLOY AFTER REMOVING FRICTION EFFECT UNDER HOT WORKING CONDITIONS

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Acta Metallurgica Sinica(English Letters) 2008年第6期21卷 451-458页

作者： z. Y. Chen S. q. Xu X.H. Dong National Die ＆ Mold CAD Engineering Research Center Shanghai Jiaotong University Shanghai 200030 China College of Materials Science and Engineering Taiyuan University of Technology Taiyuan 030024 China

The hot deformation behavior of AA6063 aluminium alloy has been investigated by means of compression tests at temperatures between 400 and 520℃, and strain rates ranging from 2.5 to 10 s^-1. Owing to the barreling, the theoretical model on the basis of Hills general method is used to calculate the flow stress of a cylindrical specimen under uniaxial simple compression so as to consider the friction effect at the die-specimen interface. A method of evaluating the friction coefficient by combining compression tests with the finite element method is presented. The real flow behavior of AA6063 aluminium alloy can be described with sinh-Arrhenius equation. The hot deformation activation energy q derived from the corrected stress and strain data is 232. 350 kJ/mol.

关键词： Barreling Compression test Friction Flow stress Aluminium alloy Activation energy