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theoretical Studies on the SAW Properties of LGS at High-temperature in Optimal Cuts

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Journal of Materials science & technology 2004年第5期20卷 512-516页

作者： xiaojun JI, tao HAN, Wenkang SHI and Guowei zhangDepartment of Instrumentation {2.,{3., shanghai 2.0030, china Dept. of Instrumentation Eng. Shanghai Jiaotong Univ. Shanghai 200030 China

Surface acoustic wave (SAW) devices play a significant role in signal processing, frequency control and sensing applications. In general, they cannot operate at elevated temperature. the new crystal of langasite provides possibility for surface acoustic wave devices applied at high temperature. this paper studies the SAW properties of single and doubly rotated cuts of LGS at high temperature. the calculated SAW properties of LGS are analyzed in space with aid of contour plots, and two promising SAW orientation regions at high temperature are presented. For some typical cuts and propagating directions within the two optimal regions, their SAW characteristics vs temperature are discussed. Based on the experimental evidence in some literatures, the reliability of calculated results is verified.

关键词： High-temperature Surface acoustic wave Langasite Optimal cuts

EXPERIMENtAL INVEStIGAtION ON tHE DRAG REDUCtION CHARACtERIStICS OF tRAVELING WAVy WALL At HIGH REyNOLDS NUMBER IN WIND tUNNEL

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Journal of Hydrodynamics 2010年第5期22卷 719-724页

作者： yAO yan LU Chuan-jing SI ting ZHU Kun Department of engineering Mechanics Shanghai Jiao Tong University Shanghai 200240 China Beijing Electromechanic engineering Institute Beijing 100074 China State Key Laboratory of Ocean engineering Shanghai Jiao Tong University Shanghai 200030 China Department of Modern Mechanics University of Science and Technology of China Hefei 230027 China

Drag reduction experiments of the traveling wavy wall at high Reynolds number, ranging from 1.46×106 to 5.83.106 based on the free-stream velocity and the model length, were conducted. A suit of traveling wavy wall device was developed and its characteristics of drag reduction at high Reynolds number were investigated. the drag forces of the traveling wavy wall with various wave speeds （ c ） were measured at different wind speeds （U ） in the FL-8 low-speed wind tunnel and compared with the drag force of the flat plate. the results show that the mean drag force of the traveling wavy wall decreases as the value of c /U increases, at different wind velocities, the values of c /U corresponding to minimal drag force of the traveling wavy wall are different, when the values of c /U are larger than 0.6, the mean drag forces of the traveling wavy wall are smaller than those of the flat plate, and the drag reduction can be up to 60%. the drag reduction effectiveness of traveling wavy wall is thus achieved. Furthermore, as the value of c /U increases, the traveling wavy wall can restrain the separation and improve the quality of flow field.

关键词： flow control drag reduction traveling wavy wall wind tunnel test

A StEEL MAtRIX WEAR RESIStANt COMPOSItE REINFORCED By IN-SItU GRANULAR EUtECtICS

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Acta Metallurgica Sinica(English Letters) 2001年第2期14卷 79-84页

作者： Z.M. Xu, t.X. Li and J.G. Li (School of Materials science and engineering,{2.,{3., china) Sch. of Mat. Sci. and Eng. Shanghai Jiaotong Univ. Shanghai 200030 China

A new steel matrix wear resistant composite reinforced by in situ granular eutectics can be obtained by modifying with a Si-Ce-ti compound in the steel melt. the result indicates that the in situ granular eutectic is a pseudo-eutectic of austenite and (Fe,Mn)3., which is formed between austenite dendrites during solidification due to the segregation of C and Mn impelled by modifying elements. the quantity of in situ granular eutectic reaches up to 8%-12. and its grain size is in the range from 10um to 2.um. the austenite steel matrix wear resistant composite reinforced by in situ granular eutectic (abbreviated AGE composite) and austenite-bainite steel mains wear resistant composite reinforced by in situ granular eutectic (abbreviated ABGE composite) are obtained in the as-cast state and by air hardening, respectively. the wear resistance of the AGE and ABGE composites can be more greatly increased than that of their matrix steels under low and medium impact working condition.

关键词： steel matrix composite Si-Ce-ti compound in situ granular eutectic mechanical property

Friction compensation design based on state observer and adaptive law for high-accuracy positioning system

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Progress in Natural science:Materials International 2006年第2期16卷 147-152页

作者： WANG ying, xiONG Zhenhua and DING Han (School of Mechanical engineering,{2.,{3., china) [a]School of Mechanical engineering Shanghai Jiao Tong University Shangai China

Friction is one of the main factors that affect the positioning accuracy of motion system. Friction compensation based on friction model is usually adopted to eliminate the nonlinear effect of friction. this paper presents a proportional-plus-derivative (PD) feedback controller with a friction compensator based on LuGre friction model. We also design a state observer to observe the unknown state of LuGre friction model, and adopt a parameter adaptive law and off-line approximation to estimate the parameters of LuGre friction model. Comparative experiments are carried out among our proposed controller, PD controller with friction compensation based on classical friction model, and PD controller without friction compensation. Experimental results demonstrate that our proposed controller can achieve better performance, especially higher positioning accuracy.

关键词： friction compensation state observer adaptive law linear motor motion control.

Variation of phytoplankton community before an induced cyanobacterial(Arthrospira platensis) bloom

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Journal of Environmental sciences 2009年第12期21卷 1632-1638页

作者： WANG Chong, HUANG yingying, HE Shengbing, LIN yan, WANG xinze, KONG Hainan School of Environmental science and {2.,{3., shanghai 2.02.0, china. [a] School of Environmental science engineering Shanghai Jiao Tong University Shanghai 200240 China

A cyanobacterial （Arthrospira platensis） bloom was induced in situ by nutrient manipulation in an enclosure. the succession of the phytoplankton community and the water chemistry variations before the appearance of bloom, as well as their relationship, were investigated. the cell pigment variations were studied simultaneously. the Pearson＇s correlation analysis showed that there was no significant correlation between water chemistry and green algal or cyanobacterial composition, indicating that water chemistry variations were not suitable to be used as indicators for cyanobacterial-bloom early-warning. However, the diversity index of the phytoplankton community decreased sharply before the bloom appeared. therefore, the dynamics of phytoplankton community was put forward to be an indicator for cyanobacterial-bloom early-warning. In addition, the cell pigment variations represented the changes of community structure, which should be useful for studying the dynamics of phytoplankton community.

关键词： bloom cyanobacteria community pigments early-warning

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)

Development and Application of High Performance X80 Line Pipe for the 2.(nd) West-East Gas Pipeline

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Journal of Iron and Steel Research International 2011年第S1期18卷 39-48页

作者： LI He-lin 1 , HUO Chun-yong 1 , JI Ling-kang 1, 2., LI yang 1, 3.(1. CNPC tubular Goods Research Institute, xi’an 710065, china 2. . School of Material {2. and engineering, xi’an jiaotong university, xi’an 710049, china 3. School of Material {2. and engineering, university of {2. and technology Beijing, Beijing 100083. china) CNPC tubular Goods Res Inst Xian 710065 Peoples R China xi An jiao {2. Univ Sch Mat Sci & Engn Xian 710049 Peoples R China Univ Sci & technol Beijing Sch Mat Sci & Engn Beijing 100083 Peoples R China

It is the development tendency of gas pipeline to improve strength of line pipe and transmission pressure, which is an important symbol of the progress of gas pipeline technology. the 2.d West-East Gas Pipeline (the 2.nd WEGP) is the largest-scale X80 high pressure gas pipeline project in the world. through the joint development project by Pipeline Company, research institute, and steel company, a series of achievements of technology have been obtained, which makes it possible to apply pressure of 12.MPa and X80 LSAW and HSAW pipe for the 2.nd WEGP. Specifications of X80 steel and pipe have been issued based on API 5L. High performance X80 steel and pipe have been developed and meets the Specification. General design conception of applying HSAW pipe and LSAW pipe on gas transmission trunk line with large diameter and high pressure has been established. Failure control of the 2.nd WEGP has been carried out to avoid failure and reduce the lost which based on analysis of pipeline failure mode. In this paper, research and development of high performance X80 welded pipe, establishment of technical route of joint application of HSAW and LSAW steel pipe and key technology of failure control are emphatically discussed.

关键词： 2.nd WEGP acicular ferrite failure control arrest toughness strain-based design

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 43.074, {2. 2.School of Mechanical engineering, shanghai jiao tong university, shanghai 2.02.0, {2. 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

AN IN SItU SURFACE COMPOSItE AND GRADIENt MAtERIAL OF Al-Si ALLOy PRODUCED By ELECtROMAGNEtIC FORCE

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Acta Metallurgica Sinica(English Letters) 2001年第5期14卷 335-340页

作者： Z.M. Xu, t.X. Li, Z.L. Zhu and y.H. Zhou School of Materials science and engineering,{2.,{3., china Sch. of Mat. Sci. and Eng. Shanghai Jiaotong Univ. Shanghai 200030 China

Because of the different conductivities between the primary phase (low electric conduc tivity) and the metal melt, electromagnetic force scarcely acts on the primary phase. thus, an electromagnetic repulsive force applied by the metal melt exerts on the pri mary phase when the movement of the melt in the direction of electromagnetic force is limited. As a result, the repulsive force exerts on the primary phase to push them to move in the direction opposite to that of the electromagnetic force when the metal melt with primary phase solidifies under an electromagnetic force field. Based on this, a new method for production of in situ surface composite and gradient material by electromagnetic force is proposed. An in situ primary Si reinforced surface composite of Al-15wt%Si alloy and gradient material of Al-l9wt%Si alloy were produced by this method. the microhardness of the primary Si is HV13.0}. the reinforced phase size is in the range from 40μm to 100μm. the wear resistance of Al-Si alloy gradient material can be more greatly increased than that of their matrix material.

关键词： Al-Si alloy electromagnetic force in situ surface composite gradient material