A hybrid model-based optimal control method for nonlinear systems using simultaneous dynamic optimization strategies

To improve the overall control performance of nonlinear systems, an optimal control method, based on the framework of hybrid systems, is proposed. Firstly, the nonlinear systems are approximated by a number of piecewise affine models which are produced by the nonlinear systems at the specified operating points, then the piecewise affine models are synthesized under the framework of hybrid systems, and an associated optimal control problem, in which decision variables involve not only admissible continuous control but also the scheduling of subsystem modes, is established. Secondly, the optimal control problem is transformed into a MIQP problem by discretization over the whole state space and admissible control space to obtain the numerical optimal solution. For speeding up the algorithm, the simultaneous method on finite elements is used to lower the dimensions of the MIQP problem. Consequently, a hybrid model-based MPC for nonlinear systems is designed, and the adverse effects of model mismatch resulted from simultaneous method is weakened by MPC strategy. Simulations and comparisons with soft-switching method, hard-switching method and MLD method, confirm that a satisfactory performance can be obtained using the presented approach.     

Toward a better understanding of behavioral intention and system usage constructs

To understand user behavior, researchers have examined intention to use, and system usage through some common conceptualizations such as actual usage, reported usage, and assessed usage. Although this entire body of research has produced important findings, it has yet to appreciably advance our theoretical understanding of behavioral intention (BI) and usage constructs. To fill this gap, this paper critically examines and compares these core variables as well as their relationships with key technology acceptance determinants. We find that (1) BI has a much higher correlation with the determinants than does usage, and thus more variance in BI than in usage can be explained; (2) BI is not a good surrogate for usage; (3) among the three usage constructs, assessed usage is the most and actual usage is the least highly correlated with BI; and (4) researchers should examine both actual usage and assessed usage in their every single study to bring to light the true relationships between system usage and its antecedents. This study thus helps IS scholars expand their baseline knowledge of these core variables, interpret the important messages conveyed by the extant literature, and conduct more fruitful and illuminating future research on user behavior.     

脉冲式激光测距仪计时系统设计与实现

激光测距技术被广泛应用于扫描成像、模式识别、目标跟踪等领域,快速、高精度的测距计时是其实现的基础。为满足上述领域的应用需要,对脉冲式激光测距的高速计时技术进行了研究。采用基于数字式内插测量方法以及高精度时间间隔测量芯片和数据处理芯片,设计并实现了激光测距仪的计时模块与数据传输模块。试验结果表明,该计时系统具有较高的测量精度,可实现测距信号的高速计算以及将测距数据快速传递至上位机的功能,对模式识别、跟踪目标等领域相关功能的实现具有应用价值。     

多核体系下的并行任务构建

基于多核体系下的系统运行效率越来越受到各行业的关注,一个系统往往是由若干软件子模块构成的.一个完整的系统可以由Tomcat,Httpd以及Lucene这3个软件模块构成.这些软件本身均进行了一定的优化,各自运行效率都良好,可是如果将它们整合成一个系统,其效率的提高仍需要从整体多方面考虑.从不同软件的子任务之间的关系入手,通过分析它们的特点,提出苦干提高整体性能的方案.研究贡献在于以下3个方面:1)线程间同步操作的消除;2)通过多任务重排提高并行度;3)系统调用的单线程化.结果表明系统整体性能得到了提高,同时,每个子任务完成的功能更加清晰明了.     

忆阻器状态逻辑中与操作的高效设计与实现

作为电阻、电容、电感之外的第4种基本电路元件,忆阻器自2008年被发现以来受到学术界和产业界的广泛关注.忆阻器的阻值记忆效应和纳米工艺制造方式使其被认为可用于构建未来更大容量和密度的存储器,逐渐替代FLASH等现有存储器件.除存储功能外,HP公司在2010年《Nature》上发表的文章表明,忆阻器还可以通过以蕴含为基础的状态逻辑实现任意逻辑运算.研究了忆阻器状态逻辑的另一种操作——与操作,提出了一种更加高效的与操作实现方法,该方法不需要增加额外的忆阻器,降低了激励电压的复杂性,减小了误差,使运算更加简便高效.最后通过SPICE模拟仿真对提出的方法进行了验证.     

油水两相流非活塞式驱替的数值算法探讨

本文讨论了油藏数值模拟中油水两相驱替的数值计算方法．通过利用特征线方法分析Buckley-Leverett方程,提出了活塞式驱替和非活塞式驱替的严格数学划分条件．由于非活塞式驱替的饱和度在全场连续,本文建议在此情况下对网格界面处相对渗透率的离散值不采用常用的在迎风方向取值的做法,而直接取相邻网格的算术平均值．数值计算结果表明,对非活塞式驱替而言,该算法不仅可以提高计算精度,而且可以减小网格取向效应．     

基于模糊控制的微型燃机燃料压力控制

针对微型燃气轮机在控制时由于压力不恒定而导致的运行效率低的问题,将模糊PID控制思想运用到控制系统。在传统的PID控制下加入模糊控制,使其PID参数具有在线自整定功能。仿真结果表明,该方法能够很好地提高压力控制效果。     

一种面向IP-SAN的多网卡绑定方法的研究与实现

针对目前IP-SAN中网络链路的性能瓶颈问题,研究了Linux现有的多网卡绑定技术,多网卡绑定技术可以增大服务器带宽,提高服务器读写IP-SAN的速率。本文基于多核处理器,提出并实现了一种面向IP-SAN的多网卡绑定方法,进而使用基于多核处理器的服务器对所提出的多网卡绑定方法进行测试评估,同时与Linux现有的多网卡绑定方法进行性能对比测试。测试结果表明,此方法可以明显增加嵌入式服务器访问IP-SAN的速率和灵活性。     

矢量控制的带式输送的动力学仿真

采用长距离、大带宽、大运量、高带速的带式输送机输送散装物料己成为带式输送机发展的主流。采用有限元分析法建立输送带的动力学模型,并采用Matlab/Simulink建立具有反馈作用的异步电机矢量控制仿真模块。对建立的带式输送机的动力学数学模型在Simulink中建立仿真模型,构建带式输送机的闭环控制仿真,以便更真实地反映实际系统。     

面向调度主站一体化的数据网格设计与实现

高性能电力应用致力于搭建用于调度数据的统一管理、集中处理平台。数据网格易于海量数据共享的特点使其适用于实现调度主站一体化。构建了调度主站数据网格的基本架构,利用网格软件Globus Toolkit建立网格环境,在此基础上配置数据库访问中间件OGSA-DAI来建立面向调度主站一体化的数据网格实验平台。