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Rietveld Quantitative Analysis of Carbides Precipitation in Normalized-tempered 2.2.Cr-1Mo-0.2.V Steel

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Journal of Wuhan university of Technology(Materials Science) 2009年第6期24卷 922-926页

作者：张永涛张汉谦 School of Materials Science and engineering Shanghai Jiaotong University Research Institute Baoshan Iron & Steel Co.Ltd.

The quantitative determination of the mass fractions of precipitates in steels is very difficult using traditional materials characterization techniques. The Rietveld full-pattern fitting algorithm was introduced to solve this problem. The precipitated multicomponents’ mass fraction of M3C, MC, M7C3 and M2.C6 were evaluated precisely and relatively quickly. It is found evolution of carbides apparently occurs during tempering at high temperatures, and a two-step transformation mechanism is proposed for M7C3 during early tempering treatment. The method is an effective way on the investigation of precipitation kinetics, which may play a promising role in propertities’ enhancement and design of the heat-resistant steels.

关键词： 2.2.Cr-1Mo-0.2.V steel rietveld quantitative analysis precipitates

Dynamic Properties of Concrete under Severe Environmental Condition

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Journal of Wuhan university of Technology(Materials Science) 2010年第5期25卷 877-882页

作者：闫东明 Department of Hydraulic and Environmental engineering Zhengzhou University Department of civil and Hydraulic engineering Dalian University of Technology

Exposure to environmental conditions can significantly influence the mechanical behavior of concrete structures in civil engineering. In this study, the effect of environmental factors, such as moisture and temperature, on the strain-rate sensitivity of concrete mixtures was systematically investigated. The strain rate varied from 10^-5s^-1 to 10^-2.^-1. From the investigation it was concluded that moisture content had a significant influence on the strain-rate sensitivity of concrete. With regard to concrete with low moisture content, temperature had little influence on the rate-dependent behavior; while for fully saturated specimens, a significant influence was observed. These phenomena were attributed to the meso-scale bonding properties of the concrete matrix. Equations were derived to characterize the ultimate strength increment of concrete with strain rate under different environmental conditions. An explanation to the dynamic failure mechanisms of concrete based on the experimental findings was proposed.

关键词： concrete strain rate moisture content temperature failure mechanism

Global optimization of tool path for five-axis flank milling with a cylindrical cutter

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Science china(Technological Sciences) 2009年第8期52卷 2449-2459页

作者： DING Han1 & ZHU LiMin2.1 State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong university of Science and Technology, Wuhan 430074, china 2.School of Mechanical {2., shanghai Jiao Tong university, shanghai 2.02.0, china State Key Laboratory of Digital Manufacturing Equipment and Technology Huazhong University of Science and Technology Wuhan 430074 China School of Mechanical engineering Shanghai Jiao Tong University Shanghai 200240 China

In this paper, optimum positioning of cylindrical cutter for five-axis flank milling of non-developable ruled surface is addressed from the perspective of surface approximation. Based on the developed interchangeability principle, global optimization of the five-axis tool path is modeled as approximation of the tool envelope surface to the data points on the design surface following the minimum zone criterion recommended by ANSI and ISO standards for tolerance evaluation. By using the signed point-to-surface distance function, tool path plannings for semi-finish and finish millings are formulated as two constrained optimization problems in a unified framework. Based on the second order Taylor approximation of the distance function, a sequential approximation algorithm along with a hierarchical algorithmic structure is developed for the optimization. Numerical examples are presented to confirm the validity of the proposed approach.

关键词： five-axis flank milling tool path optimization tool axis trajectory surface surface approximation distance function minimax optimization

A LINEAR HYBRID MODEL OF MSE AND BEM FOR FLOATING STRUCTURES IN COASTAL ZONES

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Journal of Hydrodynamics 2006年第6期18卷 649-658页

作者： ZHANG Jun MIAO Guo-ping School of Naval Architecture Ocean and Civil Engineering Shanghai Jiaotong University Shanghai 200030China The First Engineers Scientific Research Institute of the General Armaments Wuxi 214035 China

A linear hybrid model of Mild Slope Equation （MSE） and Boundary Element Method （BEM） is developed to study the wave propagation around floating structures in coastal zones. Both the wave refraction under the influence of topography and the wave diffraction by floating structures are considered. Hence, the model provides wave properties around the coastal floating structures of arbitrary shape but also the wave forces on and the hydrodynamic characteristics of the structures. Different approaches are compared to demonstrate the validity of the present hybrid model. Several numerical tests are carried out for the cases of pontoons under different circumstances. The results show that the influence of topography on the hydrodynamic characteristics of floating structures in coastal regions is important and must not be ignored in the most wave period range with practical interests.

关键词： hybrid model Mild Slope Equation (MSE),Boundary Element Method (BEM) marine floating structures,coastal regions wave propagation wave force

NUMERICAL SIMULATION OF TWO-DIMENSIONAL OVERTOPPING AGAINST SEAWALLS ARMORED WITH ARTIFICIAL UNITS IN REGULAR WAVES

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Journal of Hydrodynamics 2007年第3期19卷 322-329页

作者： LU Yong-jin LIU Hua WU Wei ZHANG Jiu-shan School of Naval Architecture Ocean and Civil Engineering Shanghai Jiaotong University Shanghai 200030 China shanghai Hydraulic engineering Design and Research Institute Shanghai 200063 China School of Naval Architecture Ocean and Civil Engineering Shanghai Jiaotong University Shanghai 200030China

A new mathematical model for the overtopping against seawalls armored with artificial units in regular waves was established. The 2.D numerical wave flume, based on the Reynolds Averaged Navier-Stokes （RANS） equations and the standard κ-ε turbulence model, was developed to simulate the turbulent flows with the free surface, in which the Volume Of Fluid （VOF） method was used to handle the large deformation of the free surface and the relaxation approach of combined wave generation and absorbing was implemented. In order to consider the effects of energy dissipation due to the armors on a slope seawall, a porous media model was proposed and implemented in the numerical wave flume. A series of physical model experiments were carried out in the same condition of the numerical simulation to determine the drag coefficient in the porous media model in terms of the overtopping discharge. Compared the computational value of overtopping over the seawall with the experimental data, the values of the effective drag coefficient was calibrated for the layers of blocks at different locations along the seawalls.

关键词： porous media overtopping seawall armored units 2.D numerical wave flume regular waves

IDENTIFICATION OF ABKOWITZ MODEL FOR SHIP MANOEUVRING MOTION USING ε-SUPPORT VECTOR REGRESSION

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Journal of Hydrodynamics 2011年第3期23卷 353-360页

作者： ZHANG Xin-guang ZOU Zao-jian School of Naval Architecture Ocean and Civil Engineering Shanghai Jiao Tong University Shanghai 200240 China School of Naval Architecture Ocean and Civil Engineering and State Key Laboratory of Ocean Engineering Shanghai Jiao Tong University Shanghai 200240 China

By analyzing the data of longitudinal speed, transverse speed and rudder angle etc. in the simulated 10°/10°zigzag test, the hydrodynamic derivatives in the Abkowitz model for ship manoeuvring motion are identified by using e-Support Vector Regression （ε -SVR）. To damp the extent of parameter drift, a series of random numbers are added into the training samples to reconstruct the training samples. The identification results of the hydrodynamic derivatives are compared with the Planar Motion Mechanism （PMM） test results to verify the identification method. By using the identified Abkowitz model, 2.°/2.° zigzag test is numerically simulated. The simulated results are compared with those obtained by using the Abkowitz model where the hydrodynamic derivatives are obtained from PMM tests. The agreement is satisfactory, which shows that the regressive Abkowitz model has a good generalization performance.

关键词： ship manoeuvring Abkowitz model parameter identification e -Support Vector Regression ( ~ -SVR)

Effect of Limestone Powder on Microstructure of Concrete

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Journal of Wuhan university of Technology(Materials Science) 2010年第2期25卷 328-331页

作者：刘数华 State Key Laboratory of Water Resource and Hydropower engineering Science Wuhan University

The effect of limestone powder on microstructure of concrete was studied by using mercury intrusion porosimetry （MIP）, backscattering scanning electron（BSE）, scanning electron mi- croscopy （SEM） and X-ray diffraction （XRD） techniques. The experimental results show that the compressive strength of concrete containing 100 kg/m3 limestone powder can meet the strength requirement. Limestone powder has not pozzolanic activity; it is still unhydrated at the age of 2. days. But its filling effect can make the paste matrix and the interfacial transition zone between matrix and aggregate denser, which will improve the performance of concrete.

关键词： concrete limestone powder microstructure filling effect hydration characteristic

Research on Digitalization of High Frequency Microplasma Arc Welding Machine with Small Welding Current

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稀有金属材料与工程 2011年第S4期40卷 79-83页

作者： He Jianping1,Huang Chen1,Jiao Fujie1,You Zhichun2.1College of Materials engineering,shanghai {2. of engineering Science,shanghai 2.162.,china2.1} WTL Welding Equipment Manufacture Co.Ltd.,shanghai 2.162.,china shanghai Univ Engn Sci Coll Mat Engn Shanghai 201620 Peoples R China shanghai WTL Welding Equipment Mfg Co Ltd Shanghai 201620 Peoples R China

The problem of digital controlling of high frequency microplasma arc welding machine has been solved through Fujitsu 16-bits single-chip processor *** welding power sources and their control systems,digital sequential control system,and digital man-machine interaction system were included in digital microplasma arc welding machine ***,which is about digital sequential control system,digital man-machine interaction system,digital controller and its interface,and controlling software program,were *** has been showed that full digitalization of high frequency microplasma arc welding machine was fulfilled,minimum welding current of the machine is 0.05A,and arc is stable and can been started unfailingly.

关键词： digitalization microplasma arc welding machine single-chip processor

Impact chaos control and stress release——A key for development of ultra fine vibration milling

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Progress in Natural Science:Materials International 2002年第5期12卷 18-23页

作者： WANG Shulin(Department of Power engineering, university of {2. for Science and Technology, {2. 2.0093, china) shanghai Univ Sci & Technol Dept Power Engn Shanghai 200093 Peoples R China

Through our previous experimental and analytical studies, it has been discovered that the key for the development of vibration milling is the impact chaos control and stress release. The necessities for the chaos control and stress release are: (i) to strictly e-liminate the sub-harmonics; (ii) to control the super-harmonics to a lower level and (iii) to load the system compressively with relatively higher period, in order that the vibration energy can be absorbed by the particles effectively and sufficiently. A new vibration model for ultra fine milling is proposed, which has wide applications in preparing ultra fine particles.

关键词： vibration mills ultra fine milling impact chaos control stress release.