复合变指数趋近律的永磁同步电机控制

针对变指数趋近律应用在永磁同步电机矢量控制中出现的抖振以及趋近滑模面较慢的问题,提出一种复合变指数趋近律的控制方法。该方法引入变指数并与加权积分复合,变指数趋近律可使其快速趋近滑模面,加快系统的反应速度;再与加权积分增益结合,能消除滑动阶段抖动切换增益严重的问题。依据所提出的方法,设计了速度控制器,并与变指数趋近律进行仿真比较。仿真结果表明:稳态时,系统转速波动小,静态误差低;负载转矩突变时,系统反应迅速,响应时间短,提升了快速响应能力。     

对称复合板冷轧过程的上限分析

采用Hill提出的速度场 ,计算了对称复合板冷轧变形过程的能量消耗 ,在此基础上对软复层对称复合板在不同参数组合下冷轧时所需的最小摩擦、最大允许的加工率、以及复合板与轧辊间的摩擦状态进行了计算和分析 ,给出了相关计算曲线。计算结果表明 ,当基体材料的相对强度和相对厚度较小时 ,复合板冷轧时的变形行为与单金属冷轧时类似 ,但当基体材料的相对强度和相对厚度较大时 ,接触表面容易产生粘着现象。     

基于RES理论的岩体失稳模式判别及其智能实现

基于完全耦合模型解决复杂岩石力学问题的方法论——岩石工程系统理论(RES)的基本原理，构造了地下工程岩体失稳模式判别的智能预测模型，并采用具有自学习、非线性映射和数据挖掘功能的模糊自组织人工神经网络模型ANN来实现RES交互作用矩阵的编码。通过一个实例说明这种方法具有良好的实用性。     

Novel approach of LY12 alloy brazing

The LY12 Al alloy was brazed with the adoption of the improved KF-CsF-AlF3 flux matching Ag-Al-Cu-Zn filler metal. The shear strength of brazed joint could reach 80% of that of the substrate and the tensile strength of butt brazed joint will be 70% of that of the substrate. This was the great progress against the traditional claim that Al alloy reinforced by heat treatment could not be brazed. The experimental results and theoretical analysis had proved that it was the key issue to remove the MgO oxide film below 503℃. The addition of rare earth La was the effective way to obtain better mechanical properties of the filler metal as well as brazed joints.     

河南省水生态文明建设试点城市生态系统健康评价

在总结城市生态系统的属性并分析其健康内涵的基础上, 通过频度统计法, 建立评价指标体系。采用海明贴 近度, 建立模糊物元模型, 对河南省第一批水生态文明城市建设试点郑州、 洛阳、 许昌 2000 年- 2013 年间城市生态 系统的健康水平进行评价, 分析影响城市生态系统健康发展的各要素, 结果表明: 郑州、 洛阳和许昌整体的城市生态 系统健康水平呈上升趋势, 但健康改善程度并不显著, 且部分指标有恶化趋势; 相同时期内, 城市生态系统的健康水 平排序由高到低依次为郑州、 洛阳、 许昌, 但其增长速率则为许昌最快、 郑州最慢; 各城市不同要素之间的健康程度 差别较大, 且不同城市各要素之间的协调性较低。因此, 未来应针对健康程度较差的要素重点发展, 提高各要素之 间的协调性, 进一步提高城市生态系统整体的健康水平。     

三相电压型逆变器的一种非线性复合控制策略研究

为了减少在三相电压型逆变器系统中应用精确线性化时选择反馈增益矩阵参数的随机性,提出将精确线性化方法和反步法结合起来应用于此系统中.首先根据非线性微分几何理论,验证了该系统仿射非线性模型满足2输入2输出系统精确线性化的条件.经过非线性坐标变换得到系统的参数严格反馈形式模型,再根据反步法的设计步骤,逐步设计虚拟控制相量和中间控制相量,使系统的状态分量具有渐近稳定性,从而得到原非线性系统的控制模型.最后通过实验验证了该复合控制策略的可行性.     

虚拟网映射竞争算法设计与分析

对网络虚拟化技术中的虚拟网映射问题及其研究现状进行了介绍,针对虚拟节点映射已知且物理网不支持路径分割的虚拟网映射问题,提出以物理网提供商收益最大化为目标的虚拟网映射竞争算法,并给出了算法的竞争比分析。实验表明,所提出的算法能提高物理网资源的负载均衡度和利用率,从而提高了虚拟网构建请求的接受率和物理网提供商的收益。     

Performance control for interconnection of identical systems: Application to PLL network design

In this paper, the problem of the control law design for interconnected identical systems ensuring the global stability and the global performance properties is under consideration. Inspired by the decentralized control law design methodology using the dissipativity input–output approach, the problem is reduced to the problem of satisfying two conditions: (i) the condition on the interconnection and (ii) the condition on the local subsystem dynamics. Both problems are efficiently solved applying a (quasi‐) convex LMI optimization and standard H_∞ synthesis. The proposed design methodology is applied to the control law design of a synchronous PLL network. Copyright © 2014 John Wiley & Sons, Ltd.     

A robust observer‐based stabilization method for systems with uncertain parameters and Lipschitz nonlinearities

This paper deals with the robust observer‐based control design for a class of Lipschitz nonlinear discrete‐time systems with parameter uncertainties. Based on the use of a reformulated Lipschitz property combined with the slack variable techniques and some mathematical artifacts, it is shown that the solution of the discrete‐time output feedback stabilization problem is conditioned by a set of bilinear matrix inequalities, which become linear matrix inequalities by freezing some scalars. Furthermore, we show that some existing and elegant results reported in the literature can be regarded as particular cases of the stability conditions presented here. Numerical examples are provided to show the validity and superiority of the proposed method. Copyright © 2015 John Wiley & Sons, Ltd.     

Chaotification of Switching Control Systems via Dwell Time Approach

In this paper, a class of switching control systems is investigated, and a novel switching control method is developed, which can be applied to generating chaos dynamics from switching control systems through dwell time restriction. A numerical example is given to illustrate the generated chaotic dynamic behavior of the systems, and the corresponding bifurcation diagram is sketched. Then, the validity of the main results is verified together with other phase portraits.