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HCWCI/Carbon Steel Bimetal Liner by Liquid-Liquid Compound Lost Foam Casting

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Journal of Iron and Steel Research International 2012年第10期19卷 13-19页

作者： XIAO Xiao-feng1,2, YE Sheng-ping2, YIN Wei-xin3. XUE Qiong4 (1. School of mechanical engineering and Automation, wuhan Textile{3., wuhan 43.073. hubei, China 2. State Key Laboratory of Material Processing and Die and Mould technology, Huazhong{3. of Science and technology, wuhan 43.074, hubei, China 3. wuhan Zhike Abrasive-Resistant Material Science and technology Development Co Ltd, wuhan 43.073. hubei, China 4. college of Science, wuhan{3. of technology, wuhan 43.079, hubei, China) School of mechanical engineering and Automation Wuhan Textile University Wuhan Hubei China State Key Laboratory of Material Processing and Die and Mould technology Huazhong University of Science and Technology Wuhan Hubei China wuhan Zhike Abrasive-Resistant Material Science and technology Development Co Ltd Wuhan Hubei China college of Science Wuhan University of Technology Wuhan Hubei China

Impact, friction and corrosion from the grinding balls and the grinding medium during the mineral processing result in liner breakage. Liner, made from Hadfield steel or alloyed steel, could not have served in wet grinding environment for more than ten months. Composite liner, made from HCWCI (high Cr white cast iron) and carbon steel, has been developed successfully with liquid-liquid composing process based on LFC (lost foam casting). The microstructure of composite was analyzed with optical microscope, SEM (scanning electron microscope)/EDX energy-dispersive X-ray and XRD (X-ray diffraction). According to micrograph, the combination region of two metals was staggered like dogtooth, no mixtures occurred between two liquid metals, and its interface presented excellent metallurgical bonding state. The results of mechanical property test show that, the hardness of HRC, the fracture toughness, and the bending strength are more than 61, 16.5 J/cm2 and 1 600 MPa, respectively. Comparison between liners made from bimetal composite and alloyed steel has also been investigated in industrial hematite ball mill. The results of eight months test in wet grinding environment prove that the service life of bimetal composite liner is three times as long as that of one made from alloyed steel.

关键词： composite liner bimetal liquid-liquid compound composite interface lost foam casting high Cr white cast iron

Determination of the Thermal Expansion Coefficient of Concrete at Early Ages by Using Temperature-stress Testing Machine

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Journal of wuhan university of technology(Materials Science) 2006年第4期21卷 146-149页

作者：霍凯成 hubei Key Laboratory of Roadway Bridge & Structure engineering Wuhan University of TechnologyWuhan 430070China

By using the uptodate temperatuer-stress testing machine, the thermal expansion coefficient of concrete at early ages was studied and indicative conclusions were achieved ： temperature rising due to hydration heat is not directly correlated with cracking, but the temperature and stress evolation process should be taken into consideration in the same time. Proper chemical admixtures and mineral cornpasitions can improve the mechanical properties of concrete such as thermal expansion coefficient, which is very indicative in practice.

关键词： concrete coefficient of thermal expansion temperature-stress test

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 1 523.1 573.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

Minimum Exact Cover Problem of Group Key Distribution

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wuhan university Journal of Natural Sciences 2009年第2期14卷 137-142页

作者： FU Xiong1,2, XU Shouzhi3.1. School of Law ,wuhan university, wuhan 43.072,{3., China 2. Department of technology, Guangzhou Luogang District People’s Court, Guangzhou 51073., Guangdong, China 3. college of Electronic engineering and Information technology, China Three Gorges university, Yichang 443.02,{3., China School of Law Wuhan University Wuhan China Department of technology Guangzhou Luogang District People’s Court Guangzhou China college of Electronic engineering and Information technology China Three Gorges University Yichang China

Secure group communications are restrained by the number of the group size, number of changes and their distribution, all existing works do not meet the commands of applications with large group size and high dynamic members. In this paper, minimum exact cover problem for group key distribution （GMECP） is presented, and a heuristic solution is testified. Then an algorithm of batch rekeying with renewing cost tending to zero is illustrated, which can process any large number of change requests with best security guaranteed. Efficiency analysis and simulation test show that the achievement can improve the efficiency of any tree-based group key management.

关键词： minimum exact cover problem group key distribution secure multicast group key management

Algorithm of graph isomorphism with threedimensional DNA graph structures

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Progress in Natural Science:Materials International 2005年第2期15卷 86-89页

作者： LIU Guangwu 1,2*, YIN Zhixiang 1,3. XU Jin1 and DONG Yafei1(1. Department of Control Science and engineering, Hua Zhong university of Science and technology,{3. 43.074, China 2. college of Transportation,{3. university of technology,{3. 43.063. China 3. Department of Mathematics and Physics, Anhui university of Science and technology, Huainan 23.001, China) Dept. of Control Science and Eng. Huazhong Univ. of Sci. and Technol. Wuhan 430074 China Coll. of Transportation Wuhan Univ. of Technology Wuhan 430063 China Dept. of Mathematics and Physics Anhui Univ. of Sci. and Technol. Huainan 232001 China

An algorithm for solving the graph isomorphism problem with 3.D DNA structures is proposed in this paper. The k-armed branched junction molecules are used to code k-degree vertices. Double stranded molecules are used to code edges. Then the molecules are mixed in a tube to be ligated. The result can be detected by gel electrophoresis. The time complexity of the algorithm is O(n2), where n is the number of vertices of the graph.

关键词： DNA computing DNA graph structure graph isomorphism

11-Round Impossible Differential Algebraic Attack for Serpent Encryption Algorithm

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wuhan university Journal of Natural Sciences 2010年第3期15卷 232-236页

作者： HU Zhihua1,2, QIN Zhongping3.1. School of Computer, wuhan university, wuhan 43.072,{3., China 2. college of Mathematical and Information Sciences,Huanggang Normal university, Huanggang 43.000,{3., China 3. School of Software engineering, Huazhong university of Science and technology, wuhan 43.074,{3., China School of Computer Wuhan University Wuhan Hubei China college of Mathematical and Information Sciences Huanggang Normal University Huanggang Hubei China School of Software engineering Huazhong University of Science and Technology Wuhan Hubei China

This paper explored algebraic features of nonlinear parts in Serpent encryption algorithm and offered an 11-round Serpent-128 impossible differential algebraic attack through utilizing the method in constructing S-box algebraic equations. The new method analyzed block ll-round Serpent with 2127 selected plaintexts and 2-29 bytes memory space at the same time of giving a new design principle of S-box anti-algebraic attack.

关键词： impossible differential Serpent algebraic equation

Regulation of eight avr genes by hrpG and hrpX in Xanthomonas campestris pv. campestris and their role in pathogenicity

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Progress in Natural Science:Materials International 2006年第12期16卷 1288-1294页

作者： XU Rongqi~ 1,3., LI Xianzhen~3. WEI Hongyu~3. JIANG Bole~2, LI Kai~3. HE Yongqiang~ 2,3., FENG Jiaxun~ 1,3.and TANG Jiliang~ 1,2 **(1. Guangxi Key Laboratory of Subtropical Bioresources Conservation and Utilization 2. The Key Laboratory of Ministry of Education for Microbial and Plant Genetic engineering 3. college of Life Science and technology, Guangxi{3., Nanning 53.004, China) Guangxi Key Laboratory of Subtropical Bioresources Conservation and Utilization Guangxi University Nanning 530004 China college of Life Science and technology Guangxi University Nanning 530004 China The Key Laboratory of Ministry of Education for Microbial and Plant Genetic engineering Guangxi University Nanning 530004 China

Eight putative avirulence genes in Xanthomonas campestris pv. campestris (Xcc) strain 8004 were characterized by Tn5gusA5 mutagenesis and gene expression analysis. The virulence test of mutants on Chinese radish showed that all mutants in individual avr genes except avrBs2 mutant were not significantly different from the wild type in virulence. The avrBs2 mutant showed reduced virulence and bacterial growth in planta. Gene expression analysis using β-glucuronidase as reporter indicated that avrBs1.1,avrBs1,avrXccB,avrXccC,avrXccE1 were regulated by hrpG, whereas avrXccA1, avrXccA2 and avrBs2 were not. RT-PCR analysis showed that all hrpG-regulated genes except avrBs1 were also regulated by hrpX. In addition, it was demonstrated that avrBs1 was responsible for elicitation of a type III dependent hypersensitive reaction (HR) on nonhost plant pepper ECW-10R, and wild type Xcc 8004 was unable to cause HR on pepper ECW-20R.

关键词： Xanthomonas campestris pv. campestris avirulence gene virulence expression analysis.

Second-order consensus in networks of dynamic agents with communication time-delays

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Journal of Systems engineering and Electronics 2010年第1期21卷 88-94页

作者： Bo Yang1,2, Huajing Fang3. and Hua Wang4 1. School of Navigation, wuhan university of technology, wuhan 43.063. P. R. China 2. wuhan Second Ship Design and Research Institute, wuhan 43.064, P. R. China 3. Department of Control Science and engineering, Huazhong university of Science and technology, wuhan 43.074, P. R. China 4. Department of Aerospace and mechanical engineering, Boston university, Boston MA02215, USA School of Navigation Wuhan University of Technology Wuhan 430063 P. R. China wuhan Second Ship Design and Research Institute Wuhan 430064 P. R. China Department of Control Science and engineering Huazhong University of Science and Technology Wuhan 430074 P. R. China Department of Aerospace and mechanical engineering Boston University Boston MA02215 USA

This paper proposes second-order consensus protocols with time-delays and gives the measure of the robustness of the protocols to the time-delay existing in the network of agents with second-order dynamics. By employing a frequency domain method, it is proven that the information states and their time derivatives of all the agents in the network achieve consensus asymptotically, respectively, for appropriate communication timedelay if the topology of weighted network is connected. Particularly, a tight upper bound on the communication time-delay that can be tolerated in the dynamic network is found. The consensus protocols are distributed in the sense that each agent only needs information from its neighboring agents, which reduces the complexity of connections between neighboring agents significantly. Numerical simulation results are provided to demonstrate the effectiveness and the sharpness of the theoretical results for second-order consensus in networks in the presence of communication time-delays.

关键词： second-order consensus protocols dynamic networks algebraic graph theory frequency domain analysis com-munication constraints.

Surface Nanocrystallization of Magnesium Alloy AZ91D by High-Energy Shot Peening

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Journal of wuhan university of technology(Materials Science) 2009年第4期24卷 515-519页

作者：张津 School of Materials Science & engineering University of Science and Technology Beijing college of Materials Science & engineering Chongqing University of Technology

High-energy shot peening （HESP）, a method to produce severe plastic deformation by high velocity flying balls, was applied on die cast magnesium alloy AZ91D. Effects of surface nanocrystallization by HESP and heat treatment at different temperatures were investigated. The mi- crostructure evolution was conducted using X-ray diffraction （XRD） and field emission scanning electronic microscopy （FESEM）. The hardness was measured by microhardness tester. The experimental results show that surface nanocrystrallization of AZ91D obtained by HESP would lead to the increase of microhardness. Low temperature heated at 100℃ for 1 h do not change the property obviously. However, both the microstructure and microhardness vary greatly after heat treatment at 400℃ for 1 h.

关键词： AZ91 D surface nanocrystallization HESP microhardnss corrosion resistance