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稀有金属材料与工程 2011年第S4期40卷 120-124页

作者： Zhang L J1,Zhang J X1,Wu B1,2.Chen L2.Gong S L2.Wang H R3 1 state key {2. of Mechanical Behavior for Materials,Xi’an Jiaotong University,Xi’an 710049,china2.power Beam Processing Dept.,Avic Beijing Aeronautical Manufacturing Technology Research Institute,Beijing 10002.,china3 School of Energy and power Engineering,Xi’an Jiaotong University,Xi’an 710049,china Xi An Jiao Tong Univ Sch Energy & Power Engn Xian 710049 Peoples R China Xi An Jiao Tong Univ State Key Lab Mech Behav Mat Xian 710049 Peoples R China Avic Beijing Aeronaut Mfg Technol Res Inst Power Beam Proc Dept Beijing 100024 Peoples R China

A three dimensional model including a non-rotational symmetry keyhole of which the geometry is calculated base on the energy balance at keyhole wall is created to simulate the heat transfer and {2. flow within the molten pool during laser full penetration welding of titanium alloy *** order to take into account the effects of multiple reflections within the keyhole,a ray tracing method is employed and the coordinate dependent heat flux obtained is exerted on keyhole wall during the simulation on the heat transfer and {2. flow within molten ***,the computed weld cross sectional profile is compared with the experimental result to verify the model and it is fond that the simulation result is consists with experimental result.

关键词： laser welding titanium alloy non-rotational symmetry keyhole simulation

Analysis of Dynamic Property of High Pressure and Large Flow Rate Pneumatic On-Off Valve

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Analysis of Dynamic Property of High Pressure and Large Flow...

第五届流体传动与控制国际会议

作者： Jia Guangzheng~(1*) Ha Mingda~1 Wang Xueli~1 Wang Xuanyin~2.1)School of Mechanical Science and Engineering,Daqing Petroleum Institute,Daqing 163318,china 2.state {2. {2. of fluid power transmission and control,Zhejiang University,hangzhou 31002.,china

＜正＞Aim at the pilot solenoid high pressure and large flow rate pneumatic on-off valve structure and principle,using the subdivision principle,its mathematical model and MATLAB-Simulink simulation model are established,and its dynamic performance effect factor and rule are *** control diameter of pilot valve,control chamber diameter,cone-shaped valve diameter and control gas pressure play important roles to dynamic performance of the high pressure pneumatic control on-off valve,but the friction force,spring rigidity,mass of cone-shape valve,and so on,acting little *** effect factors on the high pressure pneumatic valve are essential difference from the conventional pressure pneumatic control valve.

关键词： high pressure pneumatic system pneumatic on-off valve subdivision principle dynamic property

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挖掘机电液流量匹配控制系统流量补偿试验

浙江大学学报（工学版） 2012年第8期46卷 1382-1389页

作者：徐兵刘伟杨华勇张圣峰浙江大学流体动力与机电系统国家重点实验室浙江杭州310027 中联重科股份有限公司湖南长沙410013

为改善挖掘机液压系统的操控性和节能性,采用电比例泵和电比例多路阀同步控制方式的电液流量匹配控制系统.以2.挖掘机试验样机为研究对象,分析电液流量匹配控制系统的结构原理和特点;针对挖掘机轻重负载不同工况,测试系统的压力和流量特... 详细信息

为改善挖掘机液压系统的操控性和节能性,采用电比例泵和电比例多路阀同步控制方式的电液流量匹配控制系统.以2.挖掘机试验样机为研究对象,分析电液流量匹配控制系统的结构原理和特点;针对挖掘机轻重负载不同工况,测试系统的压力和流量特性,通过试验研究基于压力特性的开环流量补偿方法.利用实时检测的油缸速度间接实现流量闭环控制,试验分析动臂、铲斗单执行器动作和复合动作的速度控制特性,并对系统进行变负载、变速度工况测试.试验结果表明:采用流量补偿方法提高系统的流量控制精度;电液流量匹配控制系统与负载敏感系统相比,泵的压力裕度减小0.6～0.7MPa,提高了系统的节能性和动态响应性.

关键词：电液流量匹配控制挖掘机流量补偿负载敏感系统

The onset and advance of the Asian summer monsoon

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Science Bulletin 2006年第1期51卷 80-88页

作者： Lü Junmei1,2.4, ZHANG Qingyun1, TAO Shiyan1 & JU Jianhua3 1. state key {2. of Numerical Modeling for Atmospheric Sci- ences and Geophysical {2. Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 10002., china 2. Department of Atmospheric Sciences, Yunnan University, Kunming 650091, china 3. china Meteorological Administration Training Centre, Beijing 100081, china 4. Graduate School of Chinese Academy of Sciences, Beijing 100039, china state key {2. of Numerical Modeling for Atmospheric Sciences and Geophysical {2. Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China Department of Atmospheric Sciences Yunnan University Kunming 650091 China Graduate School of Chinese Academy of Sciences Beijing 100039 China china Meteorological Administration Training Centre Beijing 100081 China

Based on the daily outgoing longwave radiation (OLR) data from National Oceanic and At- mospheric Administration (NOAA) satellites, the Cli- mate Prediction Center’s merged analysis of pre- cipitation (CMAP) data and the National Centers for Environmental Prediction/National Center for At- mospheric Research (NCEP/NCAR) reanalysis dataset, the mean intraseasonal variability of the Asian summer monsoon (ASM) is investigated by using power spectrum analysis, band-pass filter, and diagnostic analyses. The processes of the onset and advance of monsoon over the southern part of Indo- china Peninsula, the east coast of Bay of Bengal, the South china Sea and the Indian subcontinent are explored. It is found that there is an abrupt change in OLR, precipitation and zonal wind during the onset and advance of the ASM. It is also indicated that the southern part of Indochina Peninsula and the adja- cent Andaman Sea is the region where the earliest onset of the ASM occurs in the 2.d pentad of May.

关键词： Asian summer monsoon intraseasonal variability onset advance.

A Class of Fuzzy Output Feedback Tracking controllers for Robot Manipulators with Bounded Torque Inputs

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A Class of Fuzzy Output Feedback Tracking Controllers for Ro...

基于AMESim的海流能发电装置液压传动系统的建模与仿真

第三十届中国控制会议

作者： LIU Huashan~1,LI Xiaoli~1,ZHU Shiqiang~2.1.College of Information Science and Technology,Donghua University,Shanghai 2.162.,P.R.china 2.the{2. key Lab of fluid power transmission and control,Zhejiang University,hangzhou 31002.,P.R.china

＜正＞To deal with the problem of the output feedback tracking（OFT） control with bounded torque inputs of robot manipulators,we propose a generalized fuzzy OFT controller based on a class of saturation ***,considering the fact that the output toque of joint actuators is limited,a general expression for a class of saturation functions is *** it as template,different kinds of specific saturation functions can be created to be applied in the saturated control ***,to carry out the whole closed-loop control with only position measurements,a linear filter is involved to generate a pseudo velocity error *** a third contribution,a fuzzy self-tuning regulator is added to obtain an adaptive performance in tackling the disturbances during the tracking ***,an explicit stability proof of the control systems based on the theory of singularly perturbed systems is ***,numerical simulations on a sample controller are implemented to verify the effectiveness of the proposed approach.

关键词： Robot Tracking System Fuzzy control Output Feedback Bounded Torque Input

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太阳能学报 2010年第2期31卷 222-227页

作者：张大海李伟林勇刚刘宏伟应有浙江大学流体传动及控制国家重点实验室杭州310027

通过对海流能发电装置液压传动系统的研究,建立了系统主要模块的数学模型,并基于AMESim软件平台构建了海流能发电装置液压传动系统的仿真模型,在Matlab/Simulink中设计了控制器模型,进行了联合仿真。联合仿真结果表明:采用容积调速控制... 详细信息

通过对海流能发电装置液压传动系统的研究,建立了系统主要模块的数学模型,并基于AMESim软件平台构建了海流能发电装置液压传动系统的仿真模型,在Matlab/Simulink中设计了控制器模型,进行了联合仿真。联合仿真结果表明:采用容积调速控制可以实现海流能发电装置的变速恒频控制,从而实现能量的最大捕获和输出功率稳定。

关键词：海流能发电装置液压传动系统 AMESim 联合仿真

Shear Induced Crystallization of High-Density Polyethylene

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Shear Induced Crystallization of High-Density Polyethylene

CFD simulation of pressure fluctuation characteristics in the gas-solid fluidized bed:Comparisons with experiments

The 4th Pacific Rim Conference on Rheology

作者： Qing Chen Yu-run Fan and Qiang Zhengstate key {2. of {2. power control and transmission Zhejiang University 31002. hangzhou china Department of Polymer Science and Engineering Zhejiang University 31002. hangzhou china

＜正＞ It is well known that shearing has a great impact on the crystallization of polymers. Theoretical models of flow induced polymer crystallization indicated the excessive free energy due to shearing as the major factor that determines the crystallization rate. In this study, relaxation behavior and isothermal crystallization of two commercial high-density polyethylenes （HDPE） were investigated using a rotational rheometer with cone-plate configuration. The excessive free energy is estimated by the measured shear stress and the first normal stress difference, based on a model proposed by Marrucci, in which the molecular orientation brought about by shearing is responsible for the increase of free energy. The results show that a small change of free energy can significantly increase the crystallization rate, thus the induction time of crystallization decreases rapidly as the shear rate increases. The excessive free energy and the induction time of isothermal crystallization can be correlated by an exponential function.

关键词： High-density polyethylene isothermal crystallization shear-induced relaxation behavior.

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Petroleum Science 2011年第2期8卷 211-218页

作者： Wang Qingcheng Zhang Kai Gu Hongyan Beijing Shenwu Thermal Energy Technology Co. LTD Beijing 102200 China state key {2. of Heavy Oil Processing China University of Petroleum Beijing 102249 China National Engineering Lab for Biomass power Generation Equipment North China Electric Power University Beijing 102206 China Electrical Engineering College Guizhou University Guiyang 550025 China

A simple hydrodynamic model based on two-fluid theory, taking into account the effect of discrete particles on both the gas- and solid-phase momentum equations, was used to numerically investigate the pressure fluctuation characteristics in a gas-solid fluidized bed with the aid of CFX 4.4, a commercial CFD software package, by adding user-defined Fortran subroutines. Numerical simulations together with typical experimental measurements show that pressure fluctuations originate above the distributor when a gas pulse is injected into the fluidized bed. The pressure above the bubble gradually increases due to the presence of a rising bubble. When the bubble passes through the bed surface, the pressure near the bed surface gradually decreases to a lower value. Moreover, the pressure signals in the bubbling fluidized beds show obviously periodic characteristics. The major frequency of pressure fluctuations at the same vertical position is affected slightly by the operating gas velocity, and the amplitude of pressure fluctuations is related to both the operating gas velocity and the vertical height. In this study, the influence of the operating gas velocity on the pressure wave propagation velocity can be ignored, and only two peak frequencies in the power spectrum of the pressure fluctuations are observed which are associated with the bubble formation above the distributor and its eruption at the bed surface.

关键词： Gas-solid fluidized bed CFD simulation experimental measurements propagation ofpressure fluctuations pressure wave velocity pressure fluctuation frequency

Acoustic Wave Prediction in Flowing Steam-Water Two-Phase Mixture

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Journal of Thermal Science 1994年第3期3卷 147-154页

作者： Xu Jinliang Chen Tingkuan (state key {2. of Multiphase Flow in {2. Engineering, Xi’an Jiaotong University, Xi’an 710049,china) 1. state key {2. of Multiphase Flow in {2. Engineering Xi’an Jiaotong University 710049 Xi’an China

The transient two-fluid model has been used to develop a general relation for acoustic waves. The analysis is valid in principle over the whole void fraction region. Flow pattern transitions from one flow regime to the other are assumed to occur at certain void fractions. Different correlations are used to calculate the interfacial area and interfacial drag force per unit mixture volume for bubbly flow,slug flow and annular flow respectively. The Vapour-liquid interphase heat flux is derived from the one dimensional Fourier heat conduction equation to evaluate the interphase evaporation or condensatior *** on the present theory, a program has been carried out. Calculations are performed for pressure from 0.07 MPa to 16.0 MPa, void fractions from 0.0 to 1.0. The predicted sound speeds are compare with some experimental data for low pressures, good agreement has been achieved between sound speed predictions and experimental data.

关键词： two-phase flow perturbation wave sound speed

Optimal user scheduling and power control in multi-user cognitive broadcast systems

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Science china(Information Sciences) 2012年第6期55卷 1402-1414页

作者： WANG QunHuan 1,2.3,WANG HuiMing 1,2.3 & YIN QinYe 1,3 1 School of Electronic and Information Engineering,Xi'an Jiaotong University,Xi'an 710049,china 2.state {2. Lab for Integrated Services Networks,Xidian University,Xi'an 710071,china 3 Ministry of Education {2. Lab for Intelligent Networks and Network Security,Xi'an Jiaotong University,Xi'an 710071,china. 1. School of Electronic and Information Engineering Xi’an Jiaotong University Xi’an 710049 China2. State Key Lab for Integrated Services Networks Xidian University Xi’an 710071 China3. Ministry of Education Key Lab for Intelligent Networks and Network Security Xi’an Jiaotong University Xi’an 710071 China

Cognitive radio systems should not only have the ability to sense and exploit "frequency spectrum holes",but also the ability to sense and utilize "spatial spectrum holes".In this paper,we consider the issue of maximizing the throughput of the cognitive systems by fully utilizing "spatial spectrum holes" brought in by multiple cognitive users,in the scenario where a pair of licensed users and a cognitive broadcast system share multiple spectrum *** exploiting the channel reciprocity under the premise that the licensed system adopts the time-division-duplexing (TDD) mode,we propose a more practical cognitive access scheme that can sense the interference at the licensed user caused by the cognitive transmitter,based on the existing feedback signals from the licensed user to the licensed base *** both interferences from the licensed base station to the cognitive receiver and from the cognitive transmitter to the licensed user into consideration,we investigate the optimal user scheduling and power allocation scheme that can maximize the ergodic sum rate of the cognitive *** show that scheduling the user whose channel gain to interference and noise ratio (CGINR) is the largest for each frequency band is *** also derive the dynamic power allocation scheme meeting the three practical constraints,i.e.,the transmitter's average{2. power constraint,the power amplifier's instantaneous{2. power constraint,and the interference power constraint at the licensed *** result shows that in different coherent time intervals and different frequency bands,the power allocation has a multi-level waterfilling *** analysis shows that the strategy scheduling user with the largest CGINR introduces significant performance improvement compared with the traditional strategy scheduling user with the largest channel gain to noise ratio (CGNR).We also illustrate the impact of power constraints and the number of users on system p

关键词： cognitive radio distributed spatial spectrum holes opportunistic scheduling power allocation