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Microwave peak absorption frequency of liquid

Science china(Physics,Mechanics & Astronomy) 2008年第9期51卷 1254-1263页

作者： HAN GuangZe1 & CHEN MingDong2.1 Department of Physics,South china University of technology,Guangzhou 510640,{2. 2.Guangzhou Auto college,South china University of technology,Guangzhou 510800,{2. Department of Physics South China University of Technology Guangzhou China Guangzhou Auto college South China University of Technology Guangzhou China

Microwave-assisted extraction is a new effective method which has practical ap-plications in many fields. Microwave heating is one of its physical mechanisms,and it also has the characteristic of selectivity. When the applied microwave fre-quency equals a certain absorption frequency of the material (or specific compo-nent),the material will intensively absorb microwave energy. This is also known as resonant absorption,and the frequency is called the peak absorption frequency which depends on the physical structure of the material. In this work,dynamic hy-drogen bond energy was included in molecular activation energy; with the liquid cell model,the expression of interaction energy between dipolar molecules was derived. The rotational relaxation time was gotten from the Eyring viscosity formula. Then based on the relationship between dielectric dissipation coefficient and re-laxation time,the expression of microwave peak absorption frequency as a func-tion of the material physical structure,rotational inertia and electrical dipole mo-ment of molecules was established. These theoretical formulas were applied to water and benzene,and the calculated results agree fairly well with the experi-mental data. This work can not only deepen the study of the interaction between microwave and material,but also provide a possible guide for the experiment of microwave-assisted extraction.

关键词： microwave-assisted extraction microwave heating relaxation time liquid viscosity peak absorption fre-quency

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Study on Theory and Application of the Energy Method used for Analyzing Compressive Instability in Sheet Forming

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厦门大学学报（自然科学版） 2002年第S1期41卷 126-127页

作者： XIONG Zhi-qing 1, XIE Lan-sheng 2.(1. Department of mechanical engineering, Nanjing Institute of Techno logy, Nanjing 2.0013,{2. 2. college of mechanical and electrical engineering, Nanjing University of Aer onautics and Astronautics, Nanjing 2.0016,{2.)

It is pointed out that there was serious weakness w he n using the energy method for studying compressive plastic instability in sheet forming in the past. Where applying the deduced instability strengths to relativ e engineering analysis, theoretical solutions were away from practices. Its basi c reason is that simplified process in mathematical analysis of elastic bending energy was completely applied to that of plastic bending energy. Where the cambe r expressed by function of displacement normal to a plate was approximated to re alistic deflective camber, the displacement of deflected plate to compressed dir ection was neglected. With the aid of the improved instability strengths, the pr edictions on both critical buckling dimension of blank in cup deep-drawing with out blankholder through cylindrical die or conical die and the minimum blankhold er pressure to prevent buckling under constant load are universally in agreement with both experimental results and experiential data. On the bases of above-mentioned improvement, the approximate expressions for bo th the curvature and the twist used in equation of the energy of elastic bending are also ameliorated. Thus the obtained general equations for both the energy a nd the work done by internal force in plastic bending of a plate are more precis e than before. In the analyses of plastic buckling of shell with bending moment, the effect of bending moment is considered through the work done by simulative bending for ce. The method proposed in this paper can not only simplify analyses but also ge t practical result.

关键词： sheet forming deep-drawing buckling energy me thod

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External synchronization of two dynamical systems with uncertain parameters

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Science china(Technological Sciences) 2010年第3期53卷 731-740页

作者： HAN QingKai 1,SUN XiaoYu 2.YANG XiaoGuang 3 &WEN BangChun 1 1 School of mechanical engineering&Automation,Northeastern University,Shenyang 110004,{2. 2.School of electrical engineering,Shenyang University of technology,Shenyang 11002.,{2. 3School of mechanical engineering,The University of Birmingham,Birmingham,B15 2.T,UK School of mechanical engineering & Automation Northeastern University School of electrical engineering Shenyang University of Technology School of mechanical engineering The University of Birmingham

External synchronization is addressed as two or more dynamical systems with synchronous motions,which is also regarded as master-slave *** this paper,two dynamical systems,one employs a hysteretic term to model the friction phenomenon,the other involves a hardening stiffness component with the third order of displacement due to flexible deformation,are controlled to converge to the same *** control strategy is extended from feedback control for all parameters known to adaptive control for linear parameters unknown and all parameters *** slave system can keep synchronous motions with the movements of master via the designed control strategy even all the parameters are not *** stability of synchronization error,the transient process into synchronization and the effects of parameters on the designed controller using different control strategies are *** simulation results unfold the feasibility and effectiveness of this synchronization method.

关键词： controlled synchronization uncertain parameters hysteretic system Duffing system

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Preparation and Characterization of Chitosan/Carboxymethylated Konjac Glucomannan Blend Films

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Wuhan University Journal of Natural Sciences 2002年第1期7卷 107-112页

作者： Zheng Hua 1 , Du Yu-min 2.1. Department of Chemical engineering, Wuhan University of technology, Wuhan 430070, Hubei,{2. 2. college of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072. Hubei,{2. Department of Chemical engineering Wuhan University of Technology Wuhan Hubei China college of Chemistry and Molecular Sciences Wuhan University Wuhan Hubei China

In order to improve the mechanical and water swelling properties of the chitosan (CS) film, a series of transparent films were prepared by blending 2.(weight) chitosan acetic acid solution with 1.5%(weight) carboxymethylated konjac glucomannan (CMKGM) aqueous solution according to predetermined ratio and drying at 30°C. The morphological structure, miscibility, thermal stability, mechanical properies, and swelling capacity of the blend films were studied by infrared (IR), X-ray diffraction (XRD), differential thermal analysis (DTA), scanning electron micrograph (SEM), and measurements of the mechanical properties and swelling properties. The results demonstrated that there was strong interaction and good miscibility between CS and CMKGM resulted from intermolecular hydrogen bonding and electrostatic force. The mechanical properties in dry state and wet state, thermostability, and water swelling properties of the blend films were obviously improved. The best values of the tensile strength in the dry and wet state achieved 89 MPa and 49 MPa, respectively, when the CMKGM content was 30%(weight). The CS/ CMKGM blend films provided promising biomedical applications.

关键词： Key words chitosan carboxymethylated konjac glucomannan blend films structure characterization

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Preparation of MWNTs/Al_2._3 composites and their mechanical and electrical properties

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Science china(Technological Sciences) 2005年第6期48卷 622-631页

作者： FAN Jinpeng1,2. ZHAO Daqing1,2. XU Zening1,2.& WU Minsheng1,2.1. Department of mechanical engineering, Tsinghua University, Beijing 100084,{2. 2. Key Laboratory for Advanced Manufacturing by Materials Processing technology, Tsinghua University, Beijing 100084,{2. Department of mechanical engineering Tsinghua University Beijing 100084 China

The mechanical and electrical properties of MWNTs/Al2.3 composite prepared fabricated by hot pressing are investigated. The relation between properties and microstructure of composites is also discussed. With 4wt% MWNTs as reinforcement, the fracture toughness of composite obtained reaches 5.55 MPa·m1/2. which is 80% higher than that of pure Al2.3 obtained in the same conditions. The main toughening mechanism is CNTs’ pinning alumina grain boundaries, and the pullout of CNTs takes effect also. Through adding 2.t% MWNTs and altering the mix method, the fracture toughness of the composite obtained is 3.97 MPa·m1/2. Furthermore, the electrical resistivity is as low as 8.4×10?3 ?·m, decreasing by 14 orders of magnitude compared with pure alumina ceramics. The function of CNTs in composite is related to the distribution state of CNTs in composite, and the distribution state of CNTs in matrix is dependent on preparation procedures.

关键词： MWNTs, alumina, composite, fracture toughness, electrical properties.

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Security region based real and reactive power pricing of power system

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Science china(Technological Sciences) 2008年第12期51卷 2095-2111页

作者： YU YiXin1 & WANG YanJun1,2.1 Key Laboratory of Power System Simulation and Control of Ministry of Education,Tianjin University,Tianjin 300072.china 2.college of mechanical and electrical engineering,Agriculture University of Hebei,Baoding 071001,china Key Laboratory of Power System Simulation and Control of Ministry of Education Tianjin University college of mechanical and {2. engineering Agriculture University of Hebei

This paper develops a novel model and an algorithm of security region based real and reactive power pricing of power *** the proposed model,the reactive power production cost is represented as the opportunity *** static voltage stability region in the cut set power space(CVSR) and the practical dynamic security region(PDSR) in the injection power space are used to represent the constraints of voltage stability and transient stability,so that the consideration of this kind of constraints in the optimization becomes very *** the proposed algorithm,a decoupled optimization and iteration method of active power production cost and reactive power production cost is *** to the K-T optimality conditions,the prices of active power and reactive power,and the different components corresponding to the concerned security constraints are *** components of spot prices can reflect the influence of different node power injections on each kind of security constraints,so that through the node price all of the participants in power market can be stimulated to take an active part in maintaining the system *** illustrative example on the New England 10-genetator 39-bus System is used to demonstrate the proposed method.

关键词： static voltage stability region practical dynamic security region opportunity cost spot price active power and reactive power

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MOTION ANALYSIS AND DESIGN OF ACCUMULATOR FOR HYDRAULIC ROCK DRILL

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中国有色金属学会会刊：英文版 1996年第2期6卷 148-151页

作者： Liu Shixun(college of mechanical and {2. engineering, Central South University of technology, Changsha 410083) college of mechanical and {2. engineering Central South University of Technology Changsha 410083 China

ＭＯＴＩＯＮＡＮＡＬＹＳＩＳＡＮＤＤＥＳＩＧＮＯＦＡＣＣＵＭＵＬＡＴＯＲＦＯＲＨＹＤＲＡＵＬＩＣＲＯＣＫＤＲＩＬＬＬｉｕＳｈｉｘｕｎ（ＣｏｌｌｅｇｅｏｆＭｅｃｈａｎｉｃａｌａｎｄＥｌｅｃｔｒｉｃａｌＥｎｇｉｎｅｅｒｉ... 详细信息

ＭＯＴＩＯＮＡＮＡＬＹＳＩＳＡＮＤＤＥＳＩＧＮＯＦＡＣＣＵＭＵＬＡＴＯＲＦＯＲＨＹＤＲＡＵＬＩＣＲＯＣＫＤＲＩＬＬＬｉｕＳｈｉｘｕｎ（ＣｏｌｌｅｇｅｏｆＭｅｃｈａｎｉｃａｌａｎｄＥｌｅｃｔｒｉｃａｌＥｎｇｉｎｅｅｒｉｎｇ，ＣｅｎｔｒａｌＳｏｕｔｈＵｎ...

关键词： hydraulic accumulator diaphragm service life stretching ratio parameter design,motion analvsis

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CALCULATION OF ELASTIC ERROR OF PLANAR MECHANISM—AN EQUIVALENT METHOD

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Journal of Central South University 1999年第1期11卷 57-59页

作者： Wang Ailun Zhong Jue Chang Tiegang (college of mechanical and {2. engineering, Central South University of technology, Changsha 410083, china) college of mechanical and {2. engineering Central South University of Technology Changsha410083 China

In rigid mechanism dynamic analysis, the equivalence theorem is often used due to its simplicity and perceivability. Based on conjugation and duality between inertia energy storing element and elastic energy storing element, the equivalence theorem is used in elastic error analysis of planar mechanism. A set of calculation formula of elastic error is introduced, and these equations are similar in expression form to the rigid dynamic equation. To demonstrate the method developed, a computation example is given.

关键词： planar mechanism elastic error equivalent flexibility

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Study on Ceramic Cutting by Plasma Arc

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厦门大学学报（自然科学版） 2002年第S1期41卷 55-56页

作者： XU Wen-ji 1, FANG Jian-cheng 2. LU Yi-shen 1 (1. School of mechanical engineering, Dalian University of {2., Dalian 11602., china 2. college of mechanical engineering and Automation, Huaqiao University, Quanzhou 362.11, china)

engineering ceramics are typical difficult-to-machine materials because of high hardness and brittleness. PAC (Plasma Arc Cutting) is a very important thermal cutting process and has been successfully used in cutting stainless steel and other difficult-to-machine alloys. PAC’s application in cutting ceramics, however, is still limited because the most ceramics are not good electronic conducts, and transferred plasma arc cannot be produced between cathode and work-piece. So we presented a method of plasma arc cutting engineering ceramics with additional anode. To reduce the kerf width and to improve the kerf quality, the hydro-magnetically confined plasma arc is used to cut engineering ceramic plates. By experiments and analyses the mechanism and characteristics of hydro-magnetic confined plasma are discussed and the effects of secondary confinement on cutting quality, arc properties, and optimal process parameters are presented. When the nozzle diameter is 3 mm, the kerf width of the Al 2. 3 ceramic plate with 6 mm thickness is less than 4.6 mm, and the cutting speed reaches to 0.9～1.2.m/min. Both theoretical analysis and experimental results have proved the feasibility and validity of the newly advanced hydro-magnetic plasma arc cutting, and the following conclusion can be drawn: (1)Synthesizing the advantages of both the water-constriction and magnetic constriction, the hydro-magnetic constriction of plasma arc forms a three-dimensional constriction with improved shape and uniformity of arc column, narrower kerfs, minimal beveling of cuts and higher dross-free cutting speeds than those under either water-constriction or magnetic constriction alone.(2.Hydro-magnetic constriction is capable of improving arc stability, which is reflected in the higher arc voltage at which arc-extinction occurs, than that under any single constriction. (3)For a given diameter of nozzle, quality cut can be produced by using a lower arc current than usually required in conventional plas

关键词： plasma cutting engineering ceramic plasma confinement

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Preparation of Reactive Powder Concrete Using Fly Ash and Steel Slag Powder

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Journal of Wuhan University of technology(Materials Science) 2010年第2期25卷 349-354页

作者：彭艳周 college of Hydraulic & Enviormental engineering China Three Gorges University Key Laboratory for Silicate Materials Science and engineering of Ministry of Education Wuhan University of Technology

To decrease the cement and SF content of RPC by using ultra-fine fly ash （UFFA） and steel slag powder （SS）, the effect of these mineral admixtures on compressive strength of RPC were investigated. The experimental results indicate that the utilization of UFFA and SS in RPC is feasible and has prominent mechanical performance. The microstructure analysis （SEM and TG-DTG-DSC） demonstrated that the excellent mechanical properties of RPC containing SS and UFFA were mainly attributed to the sequential hydration filling effect of the compound system.

关键词： ultra-fine fly ash steel slag powder reactive powder concrete sequential hydration microstructure strength

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