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A formal model of fair exchange protocols

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Science in China(Series F) 2005年第4期48卷 499-512页

作者： QING Sihan1,2.3 & LI Gaicheng1,2.3 1. engineering research Center for Information Security Technology, {2. of Software, Chinese Aca- demy of Sciences, Beijing 100080, China 2. Beijing Zhongke Ansheng Corporation of Information Technology, Beijing 100080, China 3. Graduate School of the Chinese Academy of Sciences, Beijing 100039, China 1. engineering research Center for Information Security Technology Institute of Software Chinese Academy of Sciences 100080 Beijing China 2. Beijing Zhongke Ansheng Corporation of Information Technology 100080 Beijing China 3. Graduate School of the Chinese Academy of Sciences 100039 Beijing China

Based on the study of existing fair exchange protocols, this paper sets up an accurate formal model by stepwise refinement. In the process of refinement an unreliable channel is employed to simulate an attack behavior. The model provides a novel formal definition of exchanged items, and presents the formal goals for fairness, accountability, etc., reflecting the inherent requirements for fair exchange protocols across-the-board. In order to check, prove, and design fair exchange protocols effectively and efficiently, the model puts forward a novel property of abuse-freeness which applies to all fair exchange protocols, gives a formal definition for trust strand of the third party, and presents general criteria of designing a secure and effective fair exchange protocol. Taking a typical fair exchange protocol as an example, this paper presents the analysis steps of fair exchange protocols appealing to our model. An unknown attack is uncovered. The analysis reveals the process of a complete attack, discovering deeper reasons for causing an attack. Finally, we modify the flawed protocol and the revised protocol ensures the desirable properties.

关键词： events local causal relation local temporal relation global relation exchanged item security goals.

Effect of Chemical Composition on Oxide Transformation and MnS Precipitation Upon Oxide Particles in Fe-Cr Alloy by Heat Treatment

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Journal of Iron and Steel research International 2011年第S2期18卷 377-382页

作者： WANG Mao1, WANG Xin-hua1, YU Hui-xiang1, KITAMURA Shinya2. SHIBATA Hiroyuki2.(1. School of Metallurgical and Ecological engineering, University of Science and Technology Beijing, Beijing 100083, China 2. institute of Multidisciplinary {2. for Advanced Materials, Tohoku University, Sendai, Miyagi 980-8577, Japan) Univ Sci & Technol Beijing Sch Met & Ecol Engn Beijing 100083 Peoples R China Tohoku Univ Inst Multidisciplinary Res Adv Mat Sendai Miyagi 9808577 Japan

The transformation of nonmetallic inclusions and the change of MnS precipitation ratio on oxide particles during heat treatment were studied by using Fe-10%Cr alloy containing different Si and S content in the present study. The phenomenon of oxide transformation in alloy in this research was characterized according to Si content. When the Si content was lower, the typical inclusions changed from MnO?SiO2.type to MnO?Cr2.3 type by heat treatment. In the case of high S concentration, the obvious MnS area in inclusions was observed after heat treatment. It was more favorable for MnS precipitation as the S content was improved from approximately 2.×10-6 to 60×10-6. The MnS precipitation ratio on oxide particles was higher on MnO?SiO2.type than MnO-Cr2.3 type oxide particles. Besides, the ratio on the two kinds of oxides increased with increasing the time for heat treatment at 1473K as a whole. The theoretical Mn content at which MnS can precipitate agrees well with the experimental results.

关键词： nonmetallic inclusion oxide transformation Manganese Sulphide precipitation ratio heat treatment

Growth of Carbon Encapsulated Long Nickel Nanorods on Bulk Nickel Substrate

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Journal of Wuhan University of Technology(Materials Science) 2011年第1期26卷 28-32页

作者：宾晓蓓 College of Resources & Environment engineering Wuhan University of Technology

Carbon nanotube encapsulated nickel nanorods were catalytic grown via pyrolysis of oil on a bulk nickel wire substrate. X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy and Raman spectroscopy were employed to characterize the as-prepared sample. The results show that, carbon nanotubes possess several microns in length, the filled metallic nickel nanorods with a uniform diameter of 35 nm were tightly encapsulated by the carbon capsules. The detailed formation mechanism for the carbon nanotubes encapsulated nickel nanorods were discussed briefly.

关键词： carbon nanotube nickel nanorod pyrolysis core-shell

Delayed Hopf bifurcation in time-delayed slow-fast systems

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Science China(Technological Sciences) 2010年第3期53卷 656-663页

作者： ZHENG YuanGuang1 & WANG ZaiHua1,2.1 institute of Vibration engineering {2.,Nanjing University of Aeronautics and Astronautics,Nanjing 2.0016,China 2.institute of Science,PLA University of Science and Technology,Nanjing 2.1101,China 1. institute of Vibration engineering {2. Nanjing University of Aeronautics and Astronautics Nanjing 210016 China2. Institute of Science PLA University of Science and Technology Nanjing 211101 China

This paper presents an investigation on the phenomenon of delayed bifurcation in time-delayed slow-fast differential *** the two delayed's have different *** delayed bifurcation means that the bifurcation does not happen immediately at the bifurcation point as the bifurcation parameter passes through some bifurcation point,but at some other point which is above the bifurcation point by an obvious *** a time-delayed system,the evolution of the system depends not only on the present state but also on past *** this paper,the time-delayed slow-fast system is firstly simplified to a slow-fast system without time delay by means of the center manifold reduction,and then the so-called entry-exit function is defined to characterize the delayed bifurcation on the basis of Neishtadt's *** shows that delayed Hopf bifurcation exists in time-delayed slow-fast systems,and the theoretical prediction on the exit-point is in good agreement with the numerical calculation,as illustrated in the two illustrative examples.

关键词： time delay delayed bifurcation Hopf bifurcation slow-fast systems exit-point entry-exit function

Stability of a linear oscillator with damping force of the fractional-order derivative

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Science China(Physics,Mechanics & Astronomy) 2010年第2期53卷 345-352页

作者： WANG ZaiHua1,2.& HU HaiYan1 1 institute of Vibration engineering {2.,Nanjing University of Aeronautics and Astronautics,Nanjing 2.0016,China 2.institute of Science,PLA University of Science and Technology,Nanjing 2.1101,China 1. institute of Vibration engineering {2. Nanjing University of Aeronautics and Astronautics Nanjing 210016 China2. Institute of Science PLA University of Science and Technology Nanjing 211101 China

It begins with the study of damping representation of a linear vibration system of single degree of freedom (SDOF),from the view point of fractional calculus. By using the idea of stability switch,it shows that the linear term involving the fractional-order derivative of an order between 0 and 2.always acts as a damping force,so that the unique equilibrium is asymp-totically stable. Further,based on the idea of stability switch again,the paper proposes a scheme for determining the stable gain region of a linear vibration system under a fractional-order control. It shows that unlike the classical velocity feedback which can adjust the damping force only,a fractional-order feedback can adjust not only the damping force,but also the elastic re-storing force,and in addition,a fractional-order PDα control can either enlarge the stable gain region or narrow the stable gain region. For the dynamic systems described by integer-order derivatives,the asymptotical stability of an equilibrium is guaranteed if all characteristic roots stay in the open left half-plane,while for the systems with fractional-order derivatives,the asymptotical stability of an equilibrium is guaranteed if all characteristic roots stay within a sector in the complex plane. Analysis shows that the proposed method,based on the idea of stability switch,works effectively in the stability analysis of dynamical systems with fractional-order derivatives.

关键词： vibration system fractional-order derivative asymptotical stability stability switch

Dynamic calculation model and seismic response for frame supporting structure with prestressed anchors

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Science China(Technological Sciences) 2010年第7期53卷 1957-1966页

作者： DONG JianHua1’2. ZHU YanPeng1, ZHOU Yong1 & MA Wei2.1 College of Civil engineering, Lanzhou University of Technology, Lanzhou 730050, 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 1. College of Civil engineering Lanzhou University of Technology Lanzhou 730050 China2. State Key Laboratory of Frozen Soil Engineering Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China

A dynamic calculation model of frame supporting structures with prestressed anchors for the slope stability is proposed. The frame and soil are closely contacted in the role of prestressed anchors and they cannot be separated along the whole slope. The lateral displacement of frame and soil is nearly in phase. The movement characteristic satisfies the theory of elastic foundation beam. The frame is treated with elastic foundation beam in this model. The influence of prestressed anchors is simplified as linear spring and damped system related with velocity. Under the condition of horizontal earthquake excitation, the equation of vibration response is established by using the model of dynamic Winkler beam and the analytical solutions are obtained for simple harmonic vibration. This method is applied to a case record for illustration of its capability, in order to verify the method, 3D nonlinear FEM (ADINA) is used to analyze the seismic performance of this case, the comparative results show that the design and the analysis are safe and credible by using the proposed method. The calculation model provides a new way for earthquake analysis and seismic design of slope stability supported by frame structure with prestressed anchors.

关键词： frame supporting structure with prestressed anchor slope dynamic calculation model seismic performance seismic design

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. Department of Mechanics,Huazhong University of Science and Technology,Wuhan 430074,China 3. Department 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.

THz spectrum of reduced glutathione

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Science China(Physics,Mechanics & Astronomy) 2005年第5期48卷 585-592页

作者： WANG Weining1, YAN Haitao1, YUE Weiwei1, ZHAO Guozhong1, ZHANG Cunlin1, LIU Haibo2.& ZHANG Xicheng2.1. Department of Physics, Capital Normal University, Beijing 100037, China 2. Center for Terahertz research, Rensselaer Polytechnic institute, Tory, NY, USA 1. Department of Physics Capital Normal Univesity 100037 Beijing China 2. Center for Terahertz research Rensselaer Polytechnic Institute Tory NY USA

The optical characteristics of reduced glutathione molecules between 0.2.THz and 2.4 THz have been investigated by THz time-domain spectroscopy (THz-TDS). The absorption characteristics and optical parameters of the reduced glutathione purged with Nitrogen at room temperature were obtained experimentally. The measured results were fitted well with the theoretical results computed by using Density Functional Theory (DFT) in far-infrared range. Also the conformation of the reduced glutathione molecule was simulated by Gaussian 03. This work has demonstrated significantly that THz-TDS spectroscopy can further be used to study other biological molecules in biological and biomedical engineering.

关键词： THz time domain spectroscopy, reduced glutathione, absorption spectrum, biological engineering.

Preparation of graphitic carbon nitride by electrodeposition

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Chinese Science Bulletin 2003年第16期48卷 1737-1740页

作者： LI Chao1,2. CAO Chuanbao1 & ZHU Hesun1 1. research Center of Materials Science, Beijing institute of Technology, Beijing 100081, China 2. Department of Chemical {2., Zhengzhou institute of Light Industry, Zhengzhou 450002.China Correspondence should be addressed to Cao Chuanbao research Center of Materials Science Beijing Institute of Technology Beijing 100081 China Department of Chemical engineering Zhengzhou Institute of Light Industry Zhengzhou 450002 China

The CNx thin film was deposited on Si(100) substrate from a saturated acetone solution of cyanuric tri-chloride and melamine (cyanuric trichloride/melamine=1︰1.5) at room temperature. X-ray diffraction (XRD) results showed that the diffraction peaks in the pattern coincided well with those of graphite-like carbon nitride calculated in the literature. The lattice constants (a=4.79 ? c=6.90 ) for g-C3N4 matched with those of ab initio calculations (a=4.74 ? c=6.72.? quite well. X-ray photoelectron spectroscopy (XPS) measurements indicated that the elements in the de-posited films were mostly of C and N (N/C=0.75), and N (400.00 eV) bonded with C (2.7.72.eV) in the form of six-member C3N3 ring. The peaks at 800 cm-1, 1310 cm-1 and 1610 cm-1 in the Fourier transform infrared (FTIR) spec-trum indicated that triazine ring existed in the product. These results demonstrated that crystalline g-C3N4 was ob-tained in the CNx film.

关键词：沉淀薄膜饱和丙酮溶液三聚氰胺 X射线衍射石墨碳氮化合物晶格恒量光电子光谱测量法傅立叶变换红外光谱三嗪