基于滑模变结构的感应电动机直接转矩控制

针对感应电动机常规直接转矩控制中存在磁链、转矩脉动大,低速控制不精确等问题,在建立α-β坐标系感应电动机数学模型的基础上,提出了一种基于滑模变结构的新型直接转矩控制方法。该方法利用转速滑模变结构控制器代替常规直接转矩控制中的PI控制器,可有效减小常规直接转矩控制中的磁链和转矩脉动,增强了系统的稳定性。仿真结果证明了该方法的正确性。     

单参数控制的数字DC-DC变换器设计及其FPGA实现

传统的数字DC-DC变换器采用多参数控制方法,因而增加了控制器设计的复杂度和硬件开销;一种单参数控制的数字变换器控制方法被提出,其数字补偿器由一个乘法查找表和一个加法器构成,使得执行数字控制律的逻辑电路得到显著简化;在分析了控制参数对变换器性能的影响后,提出了获得系统最佳瞬态性能的设计条件;基于所提的单参数控制方法,完成了数字Buck变换器的FPGA实现,测试结果表明:在1MHz的开关频率下,对于1.8V的输出电压,电压纹波律小于1%,电压调整率为6mV/V,负载调节律为8mV/A;负载电流为0.3A时,转换效率高达91.9%。     

论虚拟财产的刑法保护

本文从犯罪论的角度分析了网络虚拟财产的法律属性,认为网络虚拟财产具有财产属性,可以作为盗窃罪的犯罪对象,盗窃网络虚拟财产具有社会危害性,应该适用《刑法》进行规制。     

刑法视角下计算机犯罪概念的辨析

本文首先简要的介绍了几种关于计算机犯罪定义的学说,然后对刑法意义上的＂计算机犯罪概念＂进行了定位,最后论述了计算机犯罪的犯罪构成,为刑法理论和司法实践中准确认定该类犯罪提供了具体依据。     

Design of robotic visual servo control based on neural network and genetic algorithm

A new visual servo control scheme for a robotic manipulator is presented in this paper, where a back propagation (BP) neural network is used to make a direct transition from image feature to joint angles without requiring robot kinematics and camera calibration. To speed up the convergence and avoid local minimum of the neural network, this paper uses a genetic algorithm to find the optimal initial weights and thresholds and then uses the BP algorithm to train the neural network according to the data given. The proposed method can effectively combine the good global searching ability of genetic algorithms with the accurate local searching feature of BP neural network. The Simulink model for PUMA560 robot visual servo system based on the improved BP neural network is built with the Robotics Toolbox of Matlab. The simulation results indicate that the proposed method can accelerate convergence of the image errors and provide a simple and effective way of robot control.     

A universal dependence for thermal conductivity of metals and dilute alloys

A universal curve relating the maximum of thermal conductivity and its respective temperature with the residual electrical resistivity has been proposed for metals and dilute alloys. Based on the equation of that curve, a comparative analysis of selected literature data of thermal conductivity of metals, which have residual electrical resistivity in the range 10^–11<₀<10^–5. cm, have been performed. Using the data for 33 metals, confirmation of the Wiedemann-Franz law for the impurity component/T of thermal conductivity was obtained, which means that _th/_el1, where _th and _el are the parameters of the electron-lattice defect interaction obtained from measurements of thermal and electrical conductivity, respectively. Examples of the failure of the Wiedemann-Franz law are also presented, exhibiting the values of _th/_el in the range 0.16 to 25. Measurements of thermal conductivity in the range 2 to 20 K and determination of the residual electrical resistivity for the samples of Cd doped with Zn and quenched were performed, resulting in values _th/_el1.     

高空作业平台臂架伸缩运动的横向振动特性

为了探究高空作业平台做伸缩运动时变幅平面内的横向振动动力学特性,针对臂架的实际搭接和支承情况,将臂架等效为根部铰接、中间弹性支承且带有集中参数的变截面变长度梁. 基于牛顿第二定律建立各臂段的运动微分方程,采用模态叠加法、结合边界条件求解臂架一系列时刻的瞬态振型函数,曲线拟合时变参数以近似表示梁的振型,并依据伽辽金截断方法,得到广义坐标下的状态空间方程. 在Matlab/Simulink环境下进行动态仿真,得到伸缩过程中臂架头部的变幅平面横向振动动态响应. 结果表明,就横向振动振幅而言,搭接简化会带来15.63%计算结果误差;支承简化会加大臂架整体刚度、减小臂架振动响应,不可取。     

基于剪切带扩展法的海底斜坡稳定性分析

简介剪切带扩展法（SBP）的原理及其在海底滑坡稳定性分析的应用;以舟山六横岛典型海底斜坡为分析案例,开展基于高斯函数的SBP和极限平衡法（LEM）斜坡稳定性对比分析研究;进行SBP输入参数对剪切带扩展系数R的敏感度分析. 研究结果显示,对于斜坡剪切带破坏长度,当剪切带扩展系数R不大于1时,LEM与SBP得到的滑坡滑裂面区域一致,当R大于1时,SBP计算得到的最终滑动区域比LEM计算得到的区域大;在斜坡发生滑动破坏区域SBP比LEM计算得到的安全系数低;地震影响因素和土体特征位移对R的影响较大.     

论儒家"差等观"及其对中国法治的影响

作为中国各种哲学渊源中影响最大的儒家思想,其“差等观”深刻地体现于家庭（族）生活、社会生活、政治和法律生活等方面的理论当中,对中国古代的法思想影响至深.在当代中国的法治建设进程中,应当对传统的“差等观”加以扬弃改造,批判继承,在全社会树立现代的、注入自由平等观的“差等观”.     

Crack initiation and propagation induced by inclusions in a nickel-base P/M superalloy under fatigue load

1 IntroductionRecently the key components in advanced aircraftengines are widely made of nickel-base P/M super-alloy. However, non-metallic inclusions are intro-duced into this material during powder metallurgyprocessing. In industry, although many method…