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A low frequency piezoelectric power harvester using a spiral-shaped bimorph

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Science china(Physics,Mechanics & Astronomy) 2006年第6期49卷 649-659页

作者： HU Yuantai1,2.HU Hongping2.& YANG Jiashi3 1. Institute of Mechanics and Sensing Technology,Central South university,Changsha 410083,china 2. {2. of Mechanics,Huazhong university of Science and Technology,Wuhan 430074,china 3. {2. of engineering Mechanics,university of Nebraska,Lincoln,NE 68588-052.,USA 1. Institute of Mechanics and Sensing Technology Central South University Changsha 410083 China 2. department of Mechanics Huazhong University of Science and Technology Wuhan 430074 China 3. department of engineering Mechanics University of Nebraska Lincoln NE 68588-0526 USA

We propose a spiral-shaped piezoelectric bimorph power harvester operating with coupled flexural and extensional vibration modes for applications to low frequency energy sources. A theoretical analysis is performed and the computational results show that the spiral structure has relatively low operating frequency compared to beam power harvesters of the same size. It is found that to optimize the performance of a piezoelectric spiral-shaped harvester careful design is needed.

关键词： spiral-shaped bimorph,piezoelectric harvester,power density.

Study on impurity desorption induced by femtosecond pulse laser based on a stochastic process model

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Science china(Technological Sciences) 2006年第1期49卷 78-88页

作者： CHI Yinsheng1, LIN Xiaohui1, ZHUANG Ping1 & CHEN Yunfei1,2.1. department of Mechanical engineering, Southeast {2., Nanjing 2.0096, china 2. Key Laboratory of MEMS of china Educational Ministry, Southeast {2., Nanjing 2.0096, china department of Mechanical engineering Southeast University Nanjing 210096 China Key Laboratory of MEMS of china Educational Ministry Southeast University Nanjing 210096 China

With the advantages on non-equilibrium heating and desorption induced by electronic transition, the femtosecond pulse laser introduces a new way for solving the problem of impurity pollution adsorbed on a solid thin film in micro-electro-mechanical systems (MEMS). A model based on stochastic processes was established for stimulated desorption induced by the femtosecond pulse laser to interpret the interaction of the opti-cally excited hot electrons with the adsorbed molecules in a metal substrate. Numerical simulation results reveal a time-dependent desorption probability of adsorbed molecules and indicate that how key parameters of femtosecond pulse laser, such as incident laser energy flux, pulse duration, and wavelength of pulse, have a great effect on the desorption probability.

关键词： desorption, femtosecond pulse laser, stochastic process.

An　Exact　Penalty　Function　Method　for　Linear　Static　Stackelberg　Problem　with　Multiple　Leaders　and　Multiple　Followers

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Systems Science and Systems engineering 1996年第3期6卷 312-318页

作者： LI Dengfeng CHEN Shouyu(department of civil {2., dalian Uaiversity of Technology, dalian, 11602., china)

The paper models and analyzes the linear static stackelberg model with multiple leaders and multiple followers in which each decision maker within his group may or may not cooperate. An exact penalty function method is developed. The duality gaps of the followers’ problems are appended to the leaders’ objective function with a penalty. This structure leads to the decomposition of the composite problem into a series of linear programming leading to an efficient algorithm. We prove that local optimality is reached for an exact penalty function and illustrste the method with three examples. Our model extends the stackelberg leader-follower model. The analysis in this paper hopefully provides some forther insights about types of the static stackelberg leader-follower model.

关键词： stackelberg game cooperation penalty function method linear programming.

Wear Performance of Laser Surface Hardened GCr15 Steel

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Journal of Wuhan university of Technology(Materials Science) 2010年第1期25卷 84-88页

作者：雷声 School of Materials Science and engineering Hefei University of Technology department of Electromechanical engineering Anhui Institute of Architecture and Industry

In order to assess the new tribological properties of laser surface hardened GCr15 steel, the wear resistance between specimens treated with laser and those of conventionally hardened under dry sliding conditions was compared. The change of wear mechanisms in laser hardened GCr15 resulted in a distinct difference in wear rates. The results showed that quenched zones not only had sufficient depth of hardening and higher hardness, but had more retained austenite and finer carbides because of a higher degree of carbide dissolution. Laser surface hardened GCr15 steel specimens exhibited superior wear resistance to their conventionally hardened specimens due to the effects of the microstructure hardening, high hardness and toughness. The wear mechanism for both the laser quenched layer and conventionally hardened layer was highly similar, generally involving adhesive, material transfer, wear-induced oxidation and plowing. When conventionally hardened block specimens rubbed against the laser hardened specimens, the surface of conventionally hardened block specimens was polished. The microstructural thermal stability was increased after laser surface treatment.

关键词： laser hardening dry sliding conditions GCr15 steel wear mechanisms

Solvation effects on brain uptakes of isomers of ^(99m)Tc brain imaging agents

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Chinese Science Bulletin 2002年第21期47卷 1786-1791页

作者： JIA Hongmei, MA Xiaohui, WANG Cunxin & LIU Boli1. department of Chemistry, Beijing Normal university, Beijing 100875,{2. 2. Center for Biomedical engineering, Beijing Polytechnic university, Beijing 10002.,{2. 1. department of Chemistry Beijing Normal University Beijing 100875 China 2. Center for Biomedical engineering Beijing Polytechnic University Beijing 100022 China

Analysis of electrostatic hydration free energies of the isomers of the 99mTc-BAT and 99mTc-DADT complexes is carried out using the computer simulation technique. The results show that not only a correlation exists between the logarithm of the brain uptake and the electrostatic hydration free energy for the isomers of 99mTc-brain radiopharmaceu-ticals, but also a linear relationship exists between the logarithm of the ratio of the brain uptake of the syn isomer to that of the anti one and the difference between the electrostatic hydration free energy of the syn-isomer and that of the anti one. Furthermore, the investigation on the important factors influencing the brain uptakes of 99mTc-radiophar-maceuticals and the reasons of the different biodistribution of the isomers of the 99mTc-complexes is explored at the molecular level. The results may provide a reference for the rational drug design of brain imaging agents.

关键词： 99mTc-brain imaging agent isomer brain uptake electro-static hydration free energy.

Multifield coupling model and its applications for pile foundation in permafrost

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Science china Earth Sciences 2005年第7期48卷 968-977页

作者： WU Yaping1,2. ZHU Yuanlin2. GUO Chunxiang1, SU Qiang1 & MA Wei2.1. School of civil engineering, Lanzhou Jiaotong {2., Lanzhou 730070, china 2. State Key Laboratory of Frozen Soil engineering, Cold and Arid Regions Environmental and engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, china School of civil engineering Lanzhou Jiaotong University Lanzhou 730070 China State Key Laboratory of Frozen Soil engineering Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China

Importing the interface element which links the frozen soil base with concrete piles and considering the couplings of stress field, temperature field and moisture field, this paper es- tablishes the nonlinear visco-elastic plastic finite element model of pile-soil. For a practical bridge structure the stress field and displacement field of single pile in freezing process are calculated. This paper emphatically studies the process of the tangential frost heave stress field, freezing stress field and displacement field varying with time, and ulteriorly studies time variation process of single pile carrying capacity in freezing process.

关键词： permafrost pile foundation freezing process multifield coupling analysis model.

A two-dimensional study on natural convection and heat transfer in the enclosure with heat transfer and radiation coupled in natural convection

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Science china(Technological Sciences) 2010年第4期53卷 991-999页

作者： ZHAN NaiYan1,2.YANG Mo1 & XU PeiWei2.1 College of Power engineering,university of Shanghai for Science and Technology,Shanghiai 2.0093,{2. 2.department of Environmental engineering,Jilin Architectural and civil engineering Institute,Changchun 13002.,{2. 1. College of Power engineering University of Shanghai for Science and Technology Shanghiai 200093 China2. Department of Environmental Engineering Jilin Architectural and Civil Engineering Institute Changchun 130021 China

Numerical investigation using SIMPLE algorithm with QUICK scheme for natural convection and heat transfer in the enclosure bounded by a solid wall and with heat transfer and radiation coupled in natural convection has been *** various parameters are:Rayleigh number(from 103 to 105),dimensionless conductivity of bounding wall(from 0 to 100),dimensionless wall thickness(from 0 to 0.6) and radiation emissivity of all surfaces(from 0 to 1).The results suggest that flow and heat transfer are influenced by *** is a dominant action on flow and heat *** increase of the thermal conductivity of wall,flow and heat transfer turn *** temperature distribution changes *** the thermal conductivity of wall is over a certain critical number,the increasing trend of flow and heat transfer may *** increase of enclosure wall thickness,flow and heat transfer turn *** the enclosure wall thickness is over a certain critical number,the flow and heat transfer will turn slow.

关键词： conduction natural convection radiation couple numerical simulation

Morphology and electrical conductivity of PACS

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Journal of Environmental Sciences 2000年第3期12卷 319-324页

作者： GAO Bao\|yu\+1, LIU Zong\|gang\+2. YUE Qin\|yan\+3, ZHAO Hua\|zhang\+3 (1. department of Environmental engineering, Shandong {2., Jinan 2.0100, china 2. Environmental Monitoring Station of Huaiyin, Jinan 2.002., china 3. department of Environ 山东大学山东济南 2 50 1 0 0 山东济南市槐荫区环境监测山东济南 2 50 0 2 2

Polyaluminium chlorides with sulfate ion(PACS) were prepared by using AlCl 3·6H 2., Al(SO 4) 3·18H 2. and Na 2.O 3 as raw materials. The effects of basicity ( r ), Al 3+ /SO 4 2. molar ratio and aging time on the morphology of PACS were observed by transmission electrical microscope. The influence of aging time on charge neutralization and coagulation effect of PACS was studied. The effects of basicity ( r ), Al 3+ /SO 4 2. molar ratio and aging time on the electrical conductivity of PACS solution were also investigated. The experimental results show that the degree of polymerization of polyaluminium chloride(PAC) increases when SO 4 2. ion is added. The higher the basicity( r ) and the longer the aging time, the larger the size of polymer PACS. The ability of PACS neutralizing the charge on Kaolinite decreases with the increase of aging time. The electrical conductivity of PACS solution(the concentration of Al 3+ ion is 0.18 mol/L) with different aging time is the function of the basicity and Al 3+ /SO 4 2. molar ratios and has its maximum at r =0.5 and Al 3+ /SO 4 2. =12.

关键词： coagulant PACS morphology transmission electron microscope electrical conductivity coagulation

Intermediate processes and critical phenomena: Theory, method and progress of fractional operators and their applications to modern mechanics

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Science china(Physics,Mechanics & Astronomy) 2006年第3期49卷 257-272页

作者： XU Mingyu1 & TAN Wenchang2.1. Institute of Applied Mathematics, School of Math & System Science, Shandong university, Jinan 2.0100, china 2. State Key Laboratory of Turbulence and Complex Systems & {2. of Mechanics and engineering Science, Peking university, Beijing 100871, china 1. Institute of Applied Mathematics School of Math & System Science Shandong University Jinan 250100 China 2. State Key Laboratory of Turbulence and Complex Systems & department of Mechanics and engineering Science Peking University Beijing 100871 China

From point of view of physics, especially of mechanics, we briefly introduce fractional operators (with emphasis on fractional calculus and fractional differential equa- tions) used for describing intermediate processes and critical phenomena in physics and mechanics, their progress in theory and methods and their applications to modern me- chanics. Some authors’ researches in this area in recent years are included. Finally, prospects and evaluation for this subject are made.

关键词： fractional operators,intermediate processes,critical phenomena,modern mechanics