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Influence of MB-value of Manufactured Sand on the Shrinkage and Cracking of High Strength Concrete

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Journal of Wuhan University of technology(Materials Science) 2009年第2期24卷 321-325页

作者：王稷良 Key Laboratory of Road Structure and Material Ministry of communications (Beijing) Research Institute of Highway Ministry of Communication

The relation between methylene blue （MB） value of MS and its limestone dust content and clay content was investigated. The effects of MB value ranging from 0.35 to 2.5 on the workability of fresh concrete and crack propagation characteristics at the age of 2. hours, and effects on the mechanical properties, dry shrinkage of the harden concrete were tested. The experimental results show that the MB value is not related with the limestone dust content of MS, but in direct proportion to clay content. With the increase of MB value, the concrete workability decreases, and the flexural strength and 7 d compressive strength reduce markedly, whearas the 2. d compressive strength is not affected. When the MB-value is less than or equal to 1.35, the change of the MB-value has a little influence on early plastic cracking and dry shrinkage property of concrete, but when the MB-value is more than 1.35, the tendency of plastic cracking and dry shrinkage is remarkable.

关键词： manufactured sand methylene blue value high strength concrete anti-cracking shrinkage

Effects of Ultrasonic Field on Microstructures and Properties of Semi-solid AZ91D Magnesium Alloy

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Journal of Wuhan University of technology(Materials Science) 2010年第4期25卷 555-560页

作者：陈国平 Mechanical engineering institute Hunan Industry University(Zhuzhou) Mechanical and Electrical engineering institute Nanchang University

The microstructure distribution rule of semi-solid AZ91D alloy treated by ultrasonic was researched, and mechanical properies of specimens before and after ultrasonic treatment were investigated ***-solid AZ91D melt specimens were processed by ultrasonic under different powers, and its microstructures and mechanical properties at different sampling points in specimens were obtained. The experimental results show that the microstructure of AZ91D alloy at different sampling points under the same ultrasonic power is different in grain size and shape, and there is also great difference among their microstructures at the same sampling point under different ultrasonic powers. AZ91D alloy treated by ultrasonic can obtain increment in both tensile strength and plasticity. Under same ultrasonic power, mechanical properties of specimen at different sampling points have obvious difference, and regularity for change of mechanical properties everywhere is similar to regularity for change of grain size and shape everywhere.

关键词： magnesium alloy AZ91D ultrasonic treatment semi-solid structure distribution rule

Detection and parameter estimation of multicomponent LFM signal based on the fractional Fourier transform

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Science in china(Series F) 2004年第2期47卷 184-198页

作者： QI Lin1, 2. TAO Ran1, ZHOU Siyong1 & WANG Yue1 1. department of Electronic engineering, Beijing {2. of technology, Beijing 100081, china 2. School of Information engineering, Zhengzhou University, Zhengzhou 450052. china Correspondence should be addressed to QI Lin (email: qilin@***) 1. department of Electronic engineering Beijing Institute of Technology 100081 Beijing China 2. School of Information engineering Zhengzhou University 450052 Zhengzhou China

This paper presents a new method for the detection and parameter estimation of multicomponent LFM signals based on the fractional Fourier transform. For the optimization in the fractional Fourier domain, an algorithm based on Quasi-Newton method is proposed which consists of two steps of searching, leading to a reduction in computation without loss of accuracy. And for multicomponent signals, we further propose a signal separation technique in the fractional Fourier domain which can effectively suppress the interferences on the detection of the weak components brought by the stronger components. The statistical analysis of the estimate errors is also performed which perfects the method theoretically, and finally, simulation results are provided to show the validity of our method.

关键词： LFM signal parameter estimation fractional Fourier transform.

Formation control for networked spacecraft in deep space:with or without communication delays and with switching topology

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Science china(Information Sciences) 2011年第3期54卷 469-481页

作者： WANG Nan 1,2. ZHANG TianWu 2.& XU JieQiong 1 1 School of Aeronautic Science and engineering, Beijing University of Aeronautics and Astronautics, Beijing 100191, china 2.{2. of Computer Science and engineering, Henan institute of engineering, Zhengzhou 451191, china 1. School of Aeronautic Science and engineering Beijing University of Aeronautics and Astronautics Beijing 100191 China2. Department of Computer Science and Engineering Henan Institute of Engineering Zhengzhou 451191 China

In this paper, several formation controllers are developed with constant and variable connected communication topology for six-degree-of-freedom (6-DOF) networked spacecraft flying in deep space with constant and time-varying communication delays considered. In the control algorithm, any explicit leader does not exist in the formation team and it is required that each spacecraft communicate only with its neighbors and therefore the required communication loads of the whole formation is greatly reduced. The proposed control strategies allow that each spacecraft can track its desired position and attitude and simultaneously the whole group moves to the desired formation and obtain its desired relative attitudes with its neighbors. Simulation results demonstrate the effectiveness of the proposed controllers.

关键词： deep space graph theory formation control communication topology delays

Game model of safety monitoring for arch dam deformation

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Science china(Technological Sciences) 2008年第S2期51卷 76-81页

作者： SU HuaiZhi1,2.WU ZhongRu1,2.GU YanChang1,2.HU Jiang1 & WEN ZhiPing3 1 College of Water Conservancy and Hydropower engineering,Hohai University,Nanjing 2.0098,china 2.National engineering Research Center of Water Resources Efficient Utilization and engineering Safety,Nanjing 2.0098,china 3 department of Computer engineering,Nanjing institute of technology,Nanjing 2.0013,china College of Water Conservancy and Hydropower engineering Hohai University Nanjing 210098 China National engineering Research Center of Water Resources Efficient Utilization and engineering Safety Nanjing 210098 China department of Computer engineering Nanjing Institute of Technology Nanjing 210013 China

Arch dam deformation is comprehensively affected by water pressure,temperature,dam's structural behavior and material properties as well as other *** them the water pressure and temperature are external factors(source factors) that cause dam deformation,and dam's structural behavior and material properties are the internal factors of deformation(resistance factors).The dam deformation is the result of the mutual game playing between source factors and resistance ***,resistance factors of structure and materials that reflect resistance character of arch dam structure are introduced into the traditional model,where structure factor is embodied by the flexibility coefficient of dam body and the maximum dam height,and material property is embodied by the elastic modulus of *** the basis of analyzing the correlation between dam deformation and resistance factors,the game model of safety monitoring for arch dam deformation is put forward.

关键词： arch dam deformation monitoring model flexibility coefficient game theory

A whisker-like carbon composite for the immobilization of laccase and its bioelectrochemistry

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Science china Chemistry 2010年第6期53卷 1332-1336页

作者： MA GuoXian1,2.ZHONG QingDong2.& LU TianHong3 1department of Chemical engineering,Shanghai {2. of technology,Shanghai 2.02.3,china 2.chool of Materials Science and engineering,Shanghai University,Shanghai 2.0072.china 3department of Chemistry,Nanjing Normal University,Nanjing 2.0097,china 1. department of Chemical engineering Shanghai Institute of Technology Shanghai 200233 China2. School of Materials Science and Engineering Shanghai University Shanghai 200072 China3. Department of Chemistry Nanjing Normal University Nanjing 210097 China

A novel mesoporous carbon/whisker-like carbon (MCWC) composite was used for the immobilization of laccase (Lac) and its bioelectrochemical behaviors were *** was confirmed by XPS that Lac was strongly adsorbed on the surface of the MCWC *** cyclic voltammetric results showed that the immobilized Lac underwent a direct quasi-reversible electrochemical *** value of the electron transfer rate constant ks was estimated to be 0.770 s-1,indicating a reasonably fast electron transfer between the immobilized Lac and the underlying *** surface concentration (I-) of Lac was estimated to be 2.730 × 10-12.mol/*** experimental results showed that the immobilized Lac displayed an appreciable electrocatalytic activity to the electrochemical reduction of *** properties could be attributed to the particular structure of loosely packed nanometer-scale carbon whiskers and the existence of a large amount of oxygen-containing *** immo- bilization method and the novel carrier (MCWC) may find new applications in fabricating the biocatalysts for biofuel cells.

关键词： laccase whisker-like carbon composite direct electrochemical reaction oxygen bioelectrochemistry

Effect of rare earths on phase transformation in as-cast ZA2. alloy dur-ing compressive creep

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Rare Metals 2003年第4期22卷 259-264页

作者： WEIXiaowei SHENBaoluo DepamnentofAppliedPhysics UniversityofElectronicScienceandTechnologyofChinaChengdu610045China DeparlanentofMetalScience SichuanUniversityChengdu610065China

The effect of the mixed rare earths of Ce on the phase transformation in ascast ZA 2. alloy during compressive was investigated under 37 MPa and at 160 deg C by X-raydiffraction technique and SEM. The results showed that the as cast microstructure of ZA 2.-RE alloyconsisted of a dendritic Al-rich alpha' surrounded by Zn-rich beta' phase, interdendritic epsilonphase and Zn-rich eta phase together with a complex Z phase which was a complex constitute compound,(RE,Cu)Al_5Zn_(16), dispersed in crystal interfaces or branch crystal interfaces and stable duringcompressive creep test at 160 deg C. The phase transformations of ZA 2.-RE alloy, decomposition ofbeta' phase arid four transformation, were delayed by the addition of rare earths, also the lamellarstructure and the spheroidized structure in ZA 2.-RE alloy were finer than in ZA 2. alloy duringcompressive creep test at 160 deg C at the same creep time, and the compressive creep resistance ofZA 2.-RE alloy was higher than that of ZA 2. alloy.

关键词： microstructure change compressive creep rare earths ZA 2. alloy

The Effect of Annealing Processes on Fish-Scaling Resistance in V-Ti-N Microalloyed Low Carbon Steel Sheets for Enameling

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Journal of Iron and Steel Research International 2011年第S1期18卷 452-458页

作者： SUN Quan-she 1,XU Chun 2.(1.Baosteel Research institute,Baoshan Iron and Steel Co.,Ltd.,Shanghai 2.1900,china 2.Material {2. department,Shanghai institute of technology,Shanghai 2.02.3,china) Baoshan Iron & Steel Co Ltd Baosteel Res Inst Shanghai 201900 Peoples R China Shanghai Inst Technol Dept Mat Engn Shanghai 200233 Peoples R China

Annealing process will have greatly influence on microstructure of V,Ti and N microalloyed low carbon steel *** this paper,the experimental steels with given amount of V,Ti and N elements were annealed at 4 routes to simulate batch annealing and continuous annealing processes,*** enameling tests for the annealed steel sheets were undergone in same enameling and firing processes to study the relationship between microstructure and *** result shows that the cold-rolled steel sheets annealed at 750 ℃for 6 minutes even for 30 minutes exhibit excellent fishscale resistance.

关键词： fishscale resistance enameling steel sheet annealing process

Computer Simulation of the Indentation Creep Tests on Particle-Reinforced Composites

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Journal of Materials Science & technology 2002年第4期18卷 335-340页

作者： Zhufeng YUE1,2.1)department of engineering Mechanics, Northwestern Polytechnical University, Xi’an 710072.{2.2.institute of Materials, Ruhr University, 44780 Bochum, Germany department of engineering Mechanics Northwestern Polytechnical University Xi'an 710072 China institute of Materials Ruhr University 44780 Bochum Germany

A systematical simulation has been carried out on the indentation creep test on particle-reinforced composites. The deformation, failure mechanisms and life are analyzed by three reasonable models. The following five factors have been considered simultaneously: creep property of the particle, creep property of the matrix, the shape of the particle, the volume fraction of the particle and the size (relative size to the particle) of the indentation indenter. For all the cases, the power law respecting to the applied stress can be used to model the steady indentation creep depth rate of the indenter, and the detail expressions have been presented. The computer simulation precision is analyzed by the two-phase model and the three-phase model. Two places of the stress concentration are found in the composites. One is ahead of the indentation indenter, where the high stress state is deduced by the edge of the indenter and will decrease rapidly near to a steady value with the creep time. The other one is at the interface, where the high stress state is deduced by the misfit of material properties between the particles and matrix. It has been found that the creep dissipation energy density other than a stress parameter can be used to be the criterion to model the debonding of the interfaces. With the criterion of the critical creep dissipation energy density, a power law to the applied stress with negative exponent can be used to model the failure life deduced by the debonding of interfaces. The influences of the shape of the particles and the matching of creep properties of particle and matrix can be discussed for the failure. With a crack model, the further growth of interface crack is analyzed, and some important experimental phenomena can be predicted. The failure mechanism which the particle will be punched into matrix has been also discussed. The critical differences between the creep properties of the particles and matrix have been calculated, after a parameter has b

关键词： Indentation creep test Particle-reinforced composites Computer simulation Deformation Failure