电流型阻抗源升压整流器

自Z源网络提出以来,阻抗源变流器得到了广泛的研究和应用,但大多是针对电压型及逆变器的。选择电流型准Z源整流器作为研究对象,在传统控制策略中加入了阻抗源电感电流的前馈控制和有源阻尼控制,得到了更高的输出范围和更好的输出波形,并通过仿真验证了控制策略的正确性。设计了1台1 kW量级的样机并进行实验验证。     

一种磁悬浮直线开关磁阻电机悬浮模块设计与分析

磁悬浮直线开关磁阻电机继承了直线开关磁阻电机的优点,结合有效的悬浮设计方案,在磁悬浮运输系统中具有一定的应用潜力。研究了磁悬浮直线开关磁阻电机的悬浮模块及其改进结构,分析磁场分布和磁路模型,在此基础上,利用有限元软件进行仿真,通过结果分析发现所提出结构具有天然解耦的结构特点,可以实现悬浮力控制和推力控制解耦以及悬浮力控制与动子前进位置解耦,通过线性调节悬浮电流即可线性控制悬浮力,使悬浮电流控制为标量控制,大大降低了悬浮控制系统的复杂性。此外,改进结构可以有效提高悬浮电流利用率,减小悬浮绕组损耗。     

桩承式路堤平面土拱应力折减系数影响因素分析

通过二维数值模拟对桩承式路堤平面土拱应力折减系数进行了分析,探讨了影响折减系数的因素及其变化规律,结果表明:抗剪强度高的土体,应力折减系数较小,土拱效应作用显著,在一定范围中填土高度的增加,使得土拱效应逐渐形成,应力折减系数逐渐减小,土拱效应逐渐增强;桩净间距的增大或桩径的减小,都会使得应力折减系数增大,削弱了土拱效应的发挥程度。     

Estimation and comparative study of JIC using different methods for 20MnMoNi55 steel

Fracture toughness is one of the key input variables to compute critical load of the structural components. The resistance against ductile fracture can be quantified either by the initiation value or by the entire resistance curve. Different standard methods like J_SZW, JSME and ASTM: E1820 etc. are mainly used to estimate the critical crack initiation value from the resistance curve developed by the J-integral test. However, the results vary from method to method and are even inconsistent for the same method. Pehrson and Landes suggested a simple method for estimation of the critical fracture toughness by identifying the critical point corresponding to the maximum load on load–displacement curve. In the present study, different standard methods along with the one suggested by Pehrson and Landes are used to find out the critical fracture toughness using 1T–CT and ½T–CT specimens of the material 20MnMoNi55 steel for varying temperatures and crack size. The results are analyzed to compare the merits of the different methods of estimation of fracture toughness.     

Disturbance Observer-based Adaptive Fault-tolerant Dynamic Surface Control of Nonlinear System with Asymmetric Input Saturation

International Journal of Control, Automation and Systems - In this paper, a composite fault-tolerant control problem is studied for a class of uncertain nonlinear system with asymmetric input...     

Investigating the driving factors of regional CO2 emissions in China using the IDA-PDA-MMI method

In this paper, we systematically summarized existing research on the driving factors of CO₂ emissions and found that changes in technology gap may be one of the key driving factors of CO₂ emissions. Technology efficiency, technology progress, and technology gap were decomposed by using the Meta-frontier Malmquist index (MMI), which was then combined it with the Index Decomposition Analysis (IDA) and the Production-theoretical Decomposition Analysis (PDA). Our framework was applied to Chinese provincial data from 2000 to 2016. We identified nine factors to explain changes of regional CO₂ emissions. Results demonstrate that economic scale, energy technology efficiency, and output technology efficiency increased CO₂ emissions in Eastern, Central, and Western regions of China, with the economic scale being the largest contributor. Energy structure, energy intensity, energy technology progress, and output technology progress decreased regional CO₂ emissions, with the energy technology progress playing the strongest role. Energy technology gap and output technology gap led to an increase in CO₂ emissions in Central China and, to a lesser extent, in Western China. The effects of each driving factor on CO₂ emissions varied across provinces. Finally, policy implications are suggested to reduce CO₂ emissions in China.     

大坝混凝土材料溶蚀性试验研究

采用新安江库水浸泡坝址混凝土新、老龄期岩样的方法进行水—混凝土材料的溶蚀试验,主要通过测pH值、TDS（Total Dissolved Solids）、电导率这三个有代表性的指标,来评价混凝土岩样在浸泡过程中的溶蚀情况。     

基于服务质量的多品种多工艺车间作业调度系统研究

为了有效解决多品种、多工艺条件下复杂的车间作业调度问题,提高调度的速度与质量,构建基于服务质量的车间作业调度管理系统。以某锻造企业的各生产车间作业调度为背景,通过分析该企业产品的主要类型、生产特点、工艺过程的多样化以及多品种变批量生产模式下作业调度的难点,总结出影响车间作业调度质量的主要指标,给出系统的总体结构,并讨论了系统的主要功能。     

基于惯性传感器MPU6050的滤波算法研究

针对运动体姿态角测量问题,利用惯性传感器MPU6050提出了一种参数可调的自适应显性互补滤波算法,并与经典互补滤波、显性互补滤波、基于梯度下降法的互补滤波算法及传感器数字运动处理器自带滤波算法进行了比较,分析了几种算法在工程应用中的适应性。测试结果表明,此类互补滤波算法具有思路清晰,计算量小,估算精度高及易实现等特点,改进后的算法综合性能最优,适用于各种运动姿态测量系统。     

插补前加减速运动时间周期化等效变换算法

针对数控系统插补前加减速控制计算得到的运动时间不是插补周期的整数倍的问题,提出了基于连续时间速度曲线与位移等效变换原理,生成满足插补周期整数倍特征的周期化离散速度曲线的方法,并以梯形加减速为例,详细推导了起止速度为任意正实数情况下不同加减速阶段的各个插补周期的进给速度计算公式。该方法无需改变插补周期,易于与传统伺服运动控制系统兼容。插补实例表明,提出的方法能够生成匀速运动速度严格等于指令速度的速度曲线,保证以指定的速度通过线段终点,且具有较高的运动效率与插补精度。