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Mathematic Expression of Kinetic Compensation Effect and Relationship between the Exothermic Decomposition Temperature and Critical Temperature of Thermal Explosion of Eighty-six Energetic materials

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含能材料 2001年第1期9卷 8-9页

作者： HU Rong zu 1, YANG De suo 2. ZHANG Jiao qiang 3. (1. department of Chemistry,Northwest University, Xi′an 710065,{2. 2. department of Chemistry and Chemical Engineering, Baoji College of Arts and Science, Baoji 72.007,{2. 3. department of 西北大学陕西西安 710065 宝鸡文理学院陕西 721007 西北工业大学陕西西安 710072

Two relationships are established using the least squares method,between the kinetic parameters (the apparent activation energy and pre exponential constant),and the exothermic decomposition temperature and ther... 详细信息

关键词： critical temperature of thermal explosion decomposition temperature DSC energetic materials.

Analysis on cohesive crack opening displacement considering the strain softening effect

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Science china(Physics,Mechanics & Astronomy) 2006年第1期49卷 88-101页

作者： WANG Limin1, XU Shilang2.& ZHAO Xiqiang3.1. Mechanics department, Shandong University of {2., Zibo 2.5049, china 2. Civil Engineering department, Dalian University of {2., Dalian 11602., china 3. Mathematics department, Ocean University of china, Qingdao 2.6071, china Mechanics department Shandong University of Technology Zibo China Civil Engineering department Dalian University of Technology Dalian China Mathematics department Ocean University of China Qingdao China

In order to investigate the crack propagation in quasi-brittle materials like rock, ceramic and concrete, Hillerborg and his co-researchers abstracted the fracture process zone in front of a stress free crack in terms of a “fictitious crack zone”. On the fictitious crack zone, cohesive stresses distribute following a given softening relationship of stress vs. crack opening. Based on the polynomial or power series expression of cohesive crack opening displacement, the relationship of the cohesive stress vs. the crack opening displacement is established using elastic theory and integral equation, and some unknown physics variables are obtained using variation approach. The calculation results gained in this paper are close to the experimentally test ones.

关键词： cohesive crack, softening, dissipation work, variation approach.

Characteristics of fMRI BOLD signal and its neurophysiological mechanism

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Progress in Natural Science:materials International 2007年第6期17卷 630-638页

作者： Zhao Xiaohu1,2. Wu Yigen3.and Guo Shengli3.1. College of Life Sciences, Zhejiang University, Hangzhou 3.0058, china 2. Imaging department of Tongji Hospital of Tongji University, Shanghai 2.0065, china 3. College of Mathematics and Physics, Nanjing University of Information Science and {3., Nanjing 2.0044, china) College of Life Sciences Zhejiang University Hangzhou 310058 China Imaging department Tongji Hospital Tongji University Shanghai 200065 China College of Mathematics and Physics Nanjing University of Information Science and Technology Nanjing 210044 China

The functional magnetic resonance imaging (fMRI) based on blood oxygen level dependent (BOLD) contrast has emerged as one of the most potent noninvasive tools for mapping brain function and has been widely used to explore physiological, pathological changes and mental activity in the brain. Exploring the nature and property of BOLD signal has recently attracted more attentions. Despite that great progress has been made in investigation of the characteristics and neurophysiological basis, the exact nature of BOLD signal remains unclear. In this paper we discuss the characteristics of BOLD signals, the nonlinear BOLD response to external stimuli and the relation between BOLD signals and neural electrophysiological recordings. Furthermore, we develop our new opinions regarding nonlinear BOLD response and make some perspectives on future study.

关键词： functional magnetic resonance imaging blood oxygen level dependent nonlinear response neural electrophysiological activity.

Thermodynamic properties of under-cooled silver melts

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Science china(Physics,Mechanics & Astronomy) 2010年第1期53卷 76-80页

作者： ZHU YuYing 1 , LI Qiang 1,2.3. WANG Ge 1 , JING Qin 2., WANG Xu 1 , GAO Ying 3.& GAO JingNa 3.1 department of Mechanical Engineering, Yanshan University, Qinhuangdao 066004, china 2.Key Laboratory of Metastable materials Science & {3., Yanshan University, Qinhuangdao 066004, china 3.department of materials Science & Engineering, hebei University of Science and {3.,{12., china department of Mechanical Engineering Yanshan University Qinhuangdao China Key Laboratory of Metastable materials Science & technology Yanshan University Qinhuangdao China department of materials Science & Engineering Hebei University of Science and Technology Shijiazhuang China

Differential scanning calorimeter technique combined with the traditional fluxing treatment was used to investigate the specific heat and related thermodynamic properties of under-cooled pure silver melts. The specific heat of the under-cooled melt showed a linear dependence on the temperature in the range of the obtained under-cooling from 0 to 198 K. The related thermodynamic properties of silver, such as the entropy change, the enthalpy change and the Gibbs free energy difference between the under-cooled melt and the solid phase, were derived from the measured specific heat. The relations between the temperature and the thermal diffusion or the thermal conductivity of the under-cooled melt were analyzed respectively.

关键词： under-cooled silver melts specific heat thermodynamic properties

Surface roughness and removal rate in magnetorheological finishing of a subsurface damage free surface

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Progress in Natural Science:materials International 2005年第6期15卷 538-544页

作者： CHENG Haobo1*, WANG Yingwei2. FENG Zhijing1 and CHENG Kai3.1. State Key Laboratory of Tribiology, Tsinghua University, Beijing 100084, china 2. {2. of Material Sciences, Changchun University of Science and technology, Changchun 13.02., china 3. Faculty of Information and Engineering Systems, City Campus, Leeds LS1 3.E, UK) State Key Laboratory of Tribiology Tsinghua University Beijing 100084 China department of Material Sciences Changchun University of Science and Technology Changchun 130021 China Faculty of Information and Engineering Systems City Campus Leeds LS1 3HE United Kingdom

Based on computer-controlled optical surfacing, a new technique called magnetorheological finishing (MRF), is presented. The new technique combines the features of conventional loose abrasive machining with a wheel shaped polishing tool. The tool incorporates a host of features and has unprecedented fabricating versatility. The pre-polishing and fine polishing processes can be performed only by adjusting different parameters. The material removal function is studied theoretically and the results of simulation present a Gaussian distribution feature. Based on the established theoretical model, material removal rate experiments involving a parabolic mirror are designed and carried out to determine the effect of controllable parameters on size of the gap between the workpiece and the polishing wheel, rotating speed of the polishing wheel, concentration of volume fraction of non-magnetic particles and polishing time. Further experiments are carried out on the surface microstructure of the workpiece, the final surface roughness with an initial value of 10.98 nm reaches 1.2. nm root mean square (RMS) after 2. min of polishing. The subsurface damage experiment and the atomic force microscopy (AFM) measurement on the polished surface can also verify the feasibility of the MRF technique.

关键词： magnetorheological finishing surface roughness computer controlled optical surfacing subsurface damage removal function.

Interfacial Microstructure and Properties of Ti(C, N)/Ni Bonded by Transient Liquid-phase Diffusion

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Journal of Wuhan University of technology(materials Science) 2009年第3期24卷 432-439页

作者：周世权熊惟皓 School of Mechanical Science and Engineering Huazhong University of Science and Technology department of Mechanical Engineering University of Waterloo School of materials Science and Engineering Huazhong University of Science and Technology

Effects of the main process parameters（temperature and time） on microstructure and properties of Ti（C, N）/Ni interface bonded by （Cu＋Nb） interlayer in a vacuum diffusion bonding device were investigated. The interfacial microstructures consisted initially of Ni3.b metallic compound and eutectic of Ni3.b ＋ CuNiss, and finally transformed to （Ti, Nb）（C, N）＋Ni3.b near Ti （C, N） and NiCuss ＋ Ni3.b near Ni when diffusion bonding temperature was 1 52.0}1 573.K. It was clear that Cu was a constituent in the transient liquid phase （TLP） into which Ni was dissolved by forming Cu-Ni transition liquid. Nb was dissolved in Cu-Ni transition liquid rapidly. Ti （C, N） conld be wetted by resultant Ni-Nb-Cu transient liquid phase which was followed by a little （Ti, Nb）（C, N） solid solution formed at interface. This increased the interface combining capability. Ultimately the interface shear strength was able to reach 140 MPa. The theoretle analysis and experimental results show that the growth of interfacial reaction layer Ni3.b accords with parabola law, and the activation energy of diffusion reaction is 115.0±0.5 kJ/mol, while the diffusion reaction speed constant is 12.53.mm/s^1/2.

关键词： vacuum diffusion bonding transient liquid phase (TLP) diffusion bonding interlayer activation energy

Effect of Initial Microstructure on Warm Deformation Behavior of 45 Steel

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Journal of Iron and Steel Research International 2012年第8期19卷 75-78页

作者： ZHAO Xin1, YANG Xiao-ling2. JING Tian-fu3.(1. The Sixth department, Zhengzhou Institute of Aeronautics, Zhengzhou 450015, Henan,{2. 2. Zhengzhou Zhongxing Basic Constructions Development Co Ltd, Zhengzhou 450015, Henan,{2. 3. State Key Laboratory of Metastable {3. Science and technology, Qinhuangdao 066004, hebei,{2.) The Sixth department Zhengzhou Institute of Aeronautics Zhengzhou Henan China Zhengzhou Zhongxing Basic Constructions Development Co Ltd Zhengzhou Henan China State Key Laboratory of Metastable materials Science and technology Qinhuangdao Hebei China

In order to investigate the effect of initial microstructure on warm deformation behavior, some specimens of 45 steel were annealed and some quenched. Then the specimens were isothermally compressed on a Gleeble 3.00 machine. The deformation temperature range was 550 to 700 ℃ and the strain rate range was 0.001 to 0.1 s-1. An optical microscope (OM) and a transmission electron microscope (TEM) were used to study the microstructures. The results show that the microstructure of annealed specimens is ferrite and pearlite and that of quenched specimens is martensite. The flow stress of quenched specimens is higher than that of annealed ones at 550 ℃ when strain rates are greater than 0.001 s-1. However, at 600 to 700 ℃ and strain rate of 0.001 s-1, the whole flow curves of quenched specimens are below that of annealed ones. Under the rest conditions, the flow stress of quenched specimens is higher at the beginning of compression and then the opposite is true after the strain is greater than a critical value. The microstructure examination proves that the tempering and dynamic recrystallization easily occur in the specimens with martensite during warm compression, which results in the above phenomena.

关键词： warm deformation flow stress steel microstructure

Online uniform machine covering with the known largest size

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Progress in Natural Science:materials International 2007年第11期17卷 1271-1278页

作者： Cao Shunjuan1,2.and Tan Zhiyi1,3.1. department of Mathematics, Zhejiang University, Hangzhou 3.002., china 2. department of Mathematics, Zhejiang Forestry University, Hangzhou 3.13.0, china 3. State Key Laboratory of CAD & CG, Zhejiang University, Hangzhou 3.002., china) department of Mathematics Zhejiang University Hangzhou 310027 China department of Mathematics Zhejiang Forestry University Hangzhou 311300 China State Key Laboratory of CAD and CG Zhejiang University Hangzhou 310027 China

This paper investigates the semi-online scheduling problem with the known largest size on two uniform machines. The objective is to maximize the minimum machine completion time. Both lower bounds and algorithms are given. Algorithms are optimal for the majority values of s≥1, where s is the speed ratio of the two machines. The largest gap between the competitive ratio and the lower bound is about 0.064. Moreover, the overall competitive ratio 2.matches the overall lower bound.

关键词： scheduling and covering uniform machine design and analysis of algorithm online competitive ratio

Variation properties of ionospheric eclipse factor and ionospheric influence factor

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Progress in Natural Science:materials International 2005年第6期15卷 573-576页

作者： ZHAO Chunmei 1,2.*, YUAN Yunbin1, OU Jikun1 and CHEN Jinping3.1. Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan 43.077,{2. 2. Graduate School of Chinese Academy of Sciences, Beijing 10003.,{2. 3. department of Precision Instrument and Mechanology, Tsinghua University, Beijing 100084,{2.) Institute of Geodesy and Geophysics Chinese Academy of Sciences Wuhan 430077 China Graduate School Chinese Academy of Sciences Beijing 100039 China department of Precision Instrument and Mechanology Tsinghua University Beijing 100084 China

The concepts and calculation methods of ionospheric eclipse factor (IEF) and ionospheric influence factor (IFF) are further illustrated. The temporal and spacial variation properties of IEF and IFF are studied, which shows that the properties are influenced by the geographic position and season. The possibility of improving the precision of using GPS data to determine ionospheric delay based on the above variation properties is also analysed.

关键词： GPS Ionospheric eclipse factor Ionospheric influence factor