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Influence of Calcium Sulfate State and Fineness of Cement on Hydration of p.rtland Cements Using Electrical Measurement

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Journal of Wuhan University of Technology(Materials Science) 2006年第4期21卷 141-145页

作者：魏小胜 department of Civil Engineering Huazhong University of Science and Technology Wuhan 430074 China

The influence of calcium sulfate state and fineness of cement on hydration of p.rtland cement was studied using electrical resistivity measurement. The bulk resistivity curve of the paste from the abnormal cement mainly with hemihydrate had a characteristic abnormal peak and rapid increase in early p.riod. The resistivity measurement technique can be used to discriminate abnormal setting. For normal cement with gypsum, the increase in fineness of the p.rtland cement decreases the minimum resistivhy due to a higher ionic concentration and increases the 24 hour resistivity due to a reduction in macroscopic p.re size. The setting time, compressive strength, p.re structure of pastes made from different cements were carried out to comp.re the influence of water to cement ratio, calcium sulfate state and fineness. It is found that the electrical and mechanical prop.rties are strongly affected by the initial p.rosity, the presence of hemihydrate or gypsum, and the fineness of cement.

关键词： false setting electrical resistivity fineness hydration

Density functional study on enantioselective reduction of keto oxime ether with borane catalyzed by oxazaborolidine

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Science china Chemistry 2006年第4期49卷 296-307页

作者： LI Ming1, ZHENG Wenxu2 & TIAN Anmin2 1. department of Chemistry, Southwest-china Normal University, Chongqing 400715, china 2. department of Chemistry, Sichuan University, Chengdu 610064, china 1. department of Chemistry Southwest-China Normal University Chongqing 400715 China 2. department of Chemistry Sichuan University Chengdu 610064 China

The enantioselective reduction of keto oxime ether with borane catalyzed by oxazaborolidine is discussed by the density functional theory (DFT) method. The main intermediates and transition states for this reaction are optimized completely at the B3LYp/6-31g(d) level, and the transition states are verified by vibrational modes. As shown, the chirality-controlled steps for this re- action are the hydride transfer from borane to carbonyl carbon and oxime carbon of keto oxime ether, and the chirality for the reduced products is determined in these two reaction steps. In all examined reaction paths, the first hydride is transferred via a six-membered ring and the second hydride via a five-membered ring or a four-membered ring.

关键词： keto oxime ether, oxazaborolidine, enantioselective reduction, DFT.

Threshold Signature Scheme Based on Discrete Logarithm and Quadratic residue

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Wuhan University Journal of Natural Sciences 2004年第5期9卷 770-774页

作者： FEI ru-chun 1,2 , WANG Li-na 1 1.School of Computer, Wuhan University, Wuhan 430072, Hubei, china 2.department of Information Engineering, Benxi College of Metallurgy, Benxi 117022,Liaoning,china Wuhan University School of Computer Wuhan Hubei China (GRID:grid.49470.3e) (ISNI:***) Benxi College of Metallurgy Department of Information Engineering Benxi Liaoning China (GRID:grid.49470.3e) Wuhan University School of Computer Wuhan Hubei China (GRID:grid.49470.3e) (ISNI:***)

Digital signature scheme is a very imp.rtant research field in computer security and modern cryptography. A (k, n) threshold digital signature scheme is proposed by integrating digital signature scheme with Shamir secret sharing scheme. It can realize group-oriented digital signature, and its security is based on the difficulty in computing discrete logarithm and quadratic residue on some special conditions. In this scheme, effective digital signature can not be generated by anyk?1 or fewer legal users, or only by signature executive. In addition, this scheme can identify any legal user who presents incorrect p.rtial digital signature to disrupt correct signature, or any illegal user who forges digital signature. A method of extending this scheme to an Abelian group such as elliptical curve group is also discussed. The extended scheme can provide rapider computing speed and stronger security in the case of using shorter key. Key words threshold scheme - digital signature - discrete logarithm - quadratic residuc - threshold digital signature CLC number Tp 309. 7 Foundation item: Supp.rted the National Nature Science Foundation of china, Hubei province (90104005, 2002 AB0039)Biography: FEI ru-chun (1964-), male, ph. D candidate, Associated professor, research direction: information security and cryptography.

关键词： threshold scheme digital signature discrete logarithm quadratic residuc threshold digital signature

Effects of NaNbO_3-Co_2O_3 Co-additive on the prop.rties of pZN-pZT Ceramics

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Journal of Wuhan University of Technology(Materials Science) 2007年第4期22卷 722-724页

作者：邓毅华 College of Material Science and Engineering South China University of Technology department of Electronic Science and Technology Huazhong University of Science and TechnologyWuhan 430074China

NaNbO3-Co2O3 co-added pZN-pZT （pZCNNT） ceramics were prep.red using conventional solid state reaction. The piezoelectric and dielectric prop.rties were measured. The exp.rimental results show that the addition of 0.3mo1% Co2O3 leads to low dielectric loss （tgδ） in pZCNNT ceramics and the prop.r addition of NaNbO3 not only improves piezoelectric prop.rties but also decreases intensively dielectric loss and mechanical loss. The optimal ceramic having d33=310 pC/N, kp=0.59, εr=985, tgδ=0.0034, Qm=1380 was obtained.

关键词： pZN-pZT piezoelectric constant dielectric constant dielectric loss

UV-Shielding and Catalytic Characteristics of Nanoscale Zinc-Cerium Oxides

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Journal of Wuhan University of Technology(Materials Science) 2007年第4期22卷 622-625页

作者：柴希娟 School of Science and Interior Design Southwest Forestry University

Fine p.rticles of zinc-cerium oxides （ZCO） used as an ultraviolet filter were prep.red via combustion synthesis route. The catalytic activity, UV-shielding p.rformance, surface modification and application of ZCO in polyester varnish were discussed in detail. The exp.rimental results indicate that the photo-catalytic activity of ZCO is much smaller than these of ZnO and TiO2; the oxidation catalytic activity of ZCO is far lower than that of CeO2; the ZCO has shown excellent ultraviolet absorption in the range of UV; addition modified ZCO （MZCO） into polyester will enhance the UV-shielding capability of polyester.

关键词： nanoscale zinc-cerium oxides photo-catalysis oxidation catalysis UV-shielding ability surface modification

Minimal rank preserving Additive Mappings on Upp.r Triangular Matrices

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Journal of Mathematical research and Exposition 2011年第6期31卷 951-964页

作者： Yu GUO1,2,3,Jin Chuan HOU2,3 1.department of Mathematics,Shanxi Datong University,Shanxi 037009,p.r.china 2.department of Mathematics,Shanxi University,Shanxi 030006,p.r.china 3.department of Mathematics,Taiyuan University of Technology,Shanxi 030024,p.r.china department of Mathematics Shanxi Datong University department of Mathematics Shanxi University department of Mathematics Taiyuan University of Technology

The additive mappings that preserve the minimal rank on the algebra of all n × n upp.r triangular matrices over a field of characteristic 0 are characterized.

关键词： rank minimal rank upp.r triangular matrices additive mappings

robust observer-based control for uncertain discrete-time piecewise affine systems

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控制理论与应用（英文版） 2012年第2期10卷 236-243页

作者： Yahui GAO 1 , Zhiyuan LIU 2 , Hong CHEN 3 1.AVIC (Aviation Industry Corp.ration of china) china Aviation Motor Control System Institute, Wuxi Jiangsu 214063, china 2.department of Control Science and Engineering, Harbin Institute of Technology, Harbin Heilongjiang 150001, china 3.department of Control Science and Engineering, Jilin University, Changchun Jilin 130025, china AVIC (Aviation Industry Corp.ration of china) china Aviation Motor Control System Institute Wuxi Jiangsu China department of Control Science and Engineering Harbin Institute of Technology Harbin Heilongjiang China department of Control Science and Engineering Jilin University Changchun Jilin China

The main contribution of this pap.r is to present a novel robust observer-based controller design method for discrete-time piecewise affine systems with norm-bounded uncertainties. The key ideas are to construct a piecewise quadratic Lyapunov function to guarantee the stability of the closed-loop systems, ap.roximate polytopic op.rating regions by ellipsoids, and use the singular value decomposition technique to treat the constraint of matrix equality. It is shown that the suggested control method can be formulated as linear matrix inequalities that are numerically feasible with commer- cially available software. A numerical example is also given to verify the proposed ap.roach.

关键词： piecewise affine systems robust control Observer Linear matrix inequality

Effect of Nitrogen Ion Implantation on the Structure and Corrosion resistance of Equiatomic NiTi Shape Memory Alloy

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Journal of Wuhan University of Technology(Materials Science) 2006年第4期21卷 36-39页

作者：华英杰 department of Chemistry Hainan Normal University Haikou 571158China

To protect the surface of NiTi from corrosion, an ion implantation method was proposed. In the present work, a surface oxidized sample was implanted with nitrogen at energy of 100 keV. The corrosion resistarwe prop.rty was examined by the anodic polarization method in a simulated body fluid （SBF） at a temp.rature of 37 ℃ and contrasted to non-implanted NiTi samples. The composition and structure of the implanted layers were investigated by XpS. The exp.rimental results from the electrochemical measurements provide an evidence that the nitrogen ion-implantation increases the corrosion resistance of NiTi shape memory alloy.

关键词： biocompatibility NiTi shape memory alloy ion implantation corrosion resistance

Disp.rsion of ultrafine alumina in modifier solution ——the role of polar interfacial interaction

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Journal of Central South University of Technology 2001年第1期8卷 18-23页

作者： HU Yue hua 1,QIU Guan zhou 1,J.D.Miller 2 (1.department of Mineral Engineering, Central South University, Changsha 410083, china 2.department of Metallurgical Engineering, University of Utah, 412 WBB, Salt Lake City, UT 84112, USA) 1. department of Mineral Engineering Central South University 410083 Changsha China 2. department of Metallurgical Engineering University of Utah 412 WBB 84112 Salt Lake City UT USA

Disp.rsion of ultrafine alumina suspension is examined by using p.rticle size analyzer. The zeta potential and contact angle measurements were used to discuss the electrokinetic behavior and surface wettability of alumina in modifier solution, and to calculate the electrostatic interaction forces and interfacial interaction forces between alumina p.rticles. The aggregation of ultrafine alumina occurs near its pZC. Addition of modifier increases the zeta potential of alumina and its surface hydrophilicity, resulting in increase of electrostatic and hydration repulsion. It makes the suspension of ultrafine alumina completely disp.rsed. The average p.rticle size of the suspension is decreased from 1.73 μm in absence of modifier to 0.8 μm in the presence of tripolyphosphate. According to polar interfacial interaction ap.roach, the hydration forces responsible for the stability of alumina suspension in the presence of modifier have also been obtained. The extended DLVO theory is successful to describe the disp.rsion behavior of ultrafine alumina in modifier solution.

关键词： disp.rsion alumina modifier polar interfacial interaction extended DLVO theory