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Subcritical dyke propagation in a host rock with temperature-dependent viscoelastic properties

2008 IEEE International Ultrasonics Symposium

作者： Zhenhua Chen~1 Yaowu Shi~1 Haiyan Zhao~2 ~1 Institute of Advanced Materials Processing Technology School of Materials Science and engineering china.~2 department of mechanical engineering.Tsinghua University china.

＜正＞Background,Motivation and Objective Resistance spot welding is the major production technology and widely adopted in automobile body manufacture. The zinc-coated high strength steel sheet is widely used with inc...

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Subcritical dyke propagation in a host rock with temperature...

Preparation of nanoparticles with an environment-friendly approach

中国科学院地质与地球物理研究所第11届（2011年度）学术年会

作者： Zuan Chen~1 and Z.-H.Jin~2 1 Key Laboratory of the Study of Earth’s Deep Interior,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,china. 2 department of mechanical engineering,University of Maine Orono,ME 04469,USA

SUMMARY In this paper,we examine the effects of temperature-dependent viscoelastic properties of the host rock on the suberitical growth of a dyke from a magma chamber.A theoretical relationship between the velocity of subcritical dyke growth and dyke length is established using a perturbation solution of stress intensity factor at the dyke tip and a viscoelastic crack growth theory in which the temperature-dependent creep properties are taken into account. The temperature field around the dyke is calculated using an analytic *** numerical results for a dyke subcritically propagating from a magma chamber indicate that while the general dyke growth characteristics are similar to those with constant creep properties,the subcritical dyke growth velocity is increased by an order of magnitude by considering the temperature dependence of the creep ***,the subcritical growth duration before the dyke reaches the unstable growth state is significantly shortened.

关键词： Mechanic s theory and modelling Magma migration and fragmentation Volcano monitoring

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Journal of Environmental Sciences 2009年第6期21卷 727-730页

作者： YAO Kefu,PENG Zhen,FAN Xiaolin Key Laboratory of Advanced Materials Processing Technology,Ministry of Education of china.department of mechanical engineering,Tsinghua University,Beijing 100084,china. Key Laboratory of Advanced Materials Processing Technology Ministry of Education of China Department of Mechanical Engineering Tsinghua University Beijing 100084 China

Developing various approaches for preparing high performance materials has long been topics and tasks both for scientists and for engineers. Despite that many methods have been developed for preparing nanomaterials, developing simple and environment-friendly ways for preparing nanomaterials is very attractive. Here a simple approach of synthesizing Fe3O4 nanoparticles by arc-discharge submerging in water was reported. The results showed that by this method Fe3O4 nanoparticles can be synthesized at large scale. The as-prepared Fe3O4 nanoparticles exhibited uniform spherical shape and their diameters varied with arc-discharging parameters. The experimental results showed that the size of the synthesized Fe3O4 nanoparticles can be controlled through adjusting the processing parameters. Since no vacuum system has been used, the synthesizing process is greatly simplified. In addition, only cheap deionized water and industrial iron bar are used and no pollution or harmful byproducts are found in the synthesis process. It indicated that the present approach is a simple, low-cost and environment-friendly one for preparing nanoparticles.

关键词： nanoparticles preparation approach Fe3O4

Design of policy mechanism to promote cleaner production in china

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Journal of Environmental Sciences 2001年第3期13卷 346-350页

作者： ZHANG Tian zhu(department of Environmental Science and engineering, Tsinghua University, Beijing 100084, china. department of Environmental Science and engineering Tsinghua University Beijing 100084 China

In order to promote cleaner production in china. a package of policy options was presented based on the identification of the barriers encountered in the CP demonstration project and the effectiveness and feasibility of policy options for the CP implementation were analyzed. Furthermore, the policy mechanism framework was given, which composes of compulsory, economic incentive, social pressure and supportive function. Finally, the implementation strategy of the policy mechanism, in which the emphasis will be changed from compulsory policy options towards economic and social pressure policy options, was proposed.

关键词： cleaner production barrier identification policy mechanism china

STUDY ON SUB-DRY CUTTING GCr12

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Chinese Journal of mechanical engineering 2002年第1期15卷 40-42页

作者： Ren Jialong department of mechanical engineering，East china.Shipbuilding Institute， Zhengjiang 212003，china department of mechanical engineering East China Shipbuilding Institute Zhengjiang 212003 China

Through the comparison study on cutting force, cutting temperature andmachined surface quality with the sub-dry cutting traditional cooling method, it is shown thatsub-dry cutting can retard the wear of the tooled par... 详细信息

关键词： Sub-dry cutting Production without pollution Bearing steal

Expression of lignin peroxidase H2 from Phanerochaete chrysosporium by multi-copy recombinant Pichia strain

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Journal of Environmental Sciences 2009年第2期21卷 218-222页

作者： WANG Wei,WEN Xianghua department of Environmental Science and engineering,Tsinghua University,Beijing 100084,china. department of Environmental Science and engineering Tsinghua University Beijing 100084 China

The lipH2 gene, encoding the expression of lignin peroxidase, was cloned from Phanerochaete chrysosporium BKM-F-1767 and expressed in Pichia pastoris X-33, a yeast. The cDNA of LiPH2 was generated from total RNA extracted from P chrysosporium by PCR with primers that do not contain a P. chrysosporium lignin peroxidase secretion signal. The gene was then successfully inserted into the expression vector pPICZα, and resulted in the recombinant vector pPICZα-lipH2. The transformation was conducted in two ways. One was using the wild Pichia pastoris as the recipients, which results in the recombinant P. pastoris with single or low lipH2 gene copy. The second was using P. pastoris and single or low lipH2 gene copy as the recipients, which results in the recombinant P. pastoris with multi-copies of lipH2 genes. This study firstly expressed the gene lipH2 in P. pastoris and achieved the successful expression of the lipH2 depending upon the generation of a recombinant strain that contained multiple copies. The lignin peroxidase activity reached a maximum of 15 U/L after 12 h induction.

关键词： heterologous expression lignin peroxidase Pichia pastoris

Start-up strategies of UASB reactor for treatment of pharmaceutical wastewater

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Journal of Environmental Sciences 2002年第2期14卷 250-254页

作者： ZHENG Ping, HU Bao lan (department of Environmental engineering, Zhejiang University, Hangzhou 310029, china. department of Environmental engineering Zhejiang University Hangzhou 310029 Chin

Two start up strategies of upflow anaerobic sludge blanket(UASB) reactor for treatment of pharmaceutical wastewater were investigated. The results showed that both of them were workable. Compared with the strategy that started up the reactor directly using chloromycetin wastewater, the strategy that started up the reactor first using mixed wastewater and then using chloromycetin wastewater could save time by 23%. When the latter strategy was adopted the development of sludge activity fluctuated more largely and its final activity was lower, but the sludge grew faster in the course of start up.

关键词： start up toxic wastewater UASB

COUPLED SOLUTION FOR ANISOTROPIC PIEZOELECTRIC MATERIALS WITH CRACKS

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Acta Mechanica Solida Sinica 1999年第1期12卷 83-90页

作者： Hou Mishan (department of mechanical engineering,University of Petroleum,Dongying 257062,china. department of mechanical engineering University of Petroleum Dongying 257062 China

The coupled elastic and electric fields for anisotropic piezoelectric materials with electrically permeable cracks are analyzed by using Stroh formula in anisotropic elasticity. It is shown from the solution that the tangent component of the electric field strength and the normal component of the electric displacement along the faces of cracks are all constants, and the electric field intensity and electric displacement have the singularity of type (1/2) at the crack tip. The energy release rate for crack propagation depends on both the stress intensity factor and material constants. The electric field intensity and electric displacement inside electrically permeable cracks are all constants.

关键词： piezoelectric material crack stress intensify factor energy release rate

Study on Numerical Simulation of Mold Filling and Heat Transfer in Die Casting Process

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Journal of Materials Science & Technology 2000年第3期16卷 269-272页

作者： Liangrong JIA, Shoumei XIONG and Baicheng LIU (department of mechanical engineering, Tsinghua University, Beijing 100084, china. department of mechanical engineering Tsinghua University Beijing 100084 China

A 3-D mathematical model considering turbulence phenomena has been established based on a computational fluid dynamics technique, so called 3-D SOLA-VOF (Solution Algorithm-Volume of Fluid), to simulate the fluid flow of mold filling process of die casting. In addition, the mathematical model for simulating the heat transfer in die casting process has also been established. The computation program has been developed by the authors with the finite difference method (FDM) recently. As verification, the mold filling process of a S-shaped die casting has been simulated and the simulation results coincide with that of the benchmark test. Finally, as a practical application, the gating design of a motorcycle component was modified by the mold filling simulation and the dies design of another motorcycle component was optimized by the heat transfer simulation. All the optimized designs were verified by the production practice.

关键词： Study on Numerical Simulation of Mold Filling and Heat Transfer in Die Casting Process Mold Simulation