一类时滞不确定系统的鲁棒稳定性研究

本文针对一类带时滞的时变不确定系统,在其他文献研究的基础上提出一种鲁棒控制设计方法.这种方法在知道时滞的区间而不知时滞的准确量的情况下,就可以设计相应的控制器而保证系统的稳定性.最后,用事例验证了方法的有效性.     

Delay-dependent robust H∞ control for a class of uncertain switched systems with time delay

For linear switched system with both parameter uncertainties and time delay,a delay-dependent sufficient condition for the existence of a new robust H∞ feedback controller was formulated in nonlinear matrix inequalities solvable by an LMI-based iterative algorithm.Compared with the conventional state-feedback controller,the proposed controller can achieve better robust control performance since the delayed state is utilized as additional feedback information and the parameters of the proposed controllers are changed synchronously with the dynamical characteristic of the system.This design method was also extended to the case where only delayed state is available for the controller.The example of balancing an inverted pendulum on a cart demonstrates the effectiveness and applicability of the proposed design methods.     

Delay-dependent robust control for uncertain discrete singular systems with time-varying delay

The design problem of delay-dependent robust control For uncertain discrete singular systems with time-varying delay is addressed in this paper. The uncertainty is assumed to be norm-bounded. By establishing a finite sum inequality based on quadratic terms, a new delay-dependent robust stability condition is derived and expressed in terms of linear matrix inequalities （LMIs）. A suitable robust state feedback control law is presented, which guarantees that the resultant closed-loop system is regular, causal and stable for all admissible uncertainties. Numerical examples are given to demonstrate the applicability of the proposed method.     

随机需求及回收量价格敏感的闭环供应链决策模型

考虑一个既向市场提供全新产品又提供再制造品的单一产品供应链,在需求随机且回收量对回收价格敏感的情况下,为企业做出最优生产和回收决策,使供应链利润最大化.依据回收主体的不同,分别建立制造商回收时的集中决策模型与第三方回收时的分散决策模型;在随机需求环境下,给出不同决策模型的最优回收价格及全新产品与再制造品的最优产量;为分散决策模型制定协调各方利益的契约并给出最优契约参数.最后给出一个数值算例分析了回收参数对系统利润的影响.结果显示,回收参数在集中决策模型中对制造商的利润有很大的影响,而在分散模型中对回收商有较大影响.     

Multi-objective robust controller synthesis for discrete-time systems with convex polytopic uncertain domain

Multi-objective robust state-feedback controller synthesis problems for linear discrete-time uncertain systems are addressed. Based on parameter-dependent Lyapunov functions, the Gl2 and GH2 norm expressed in terms of LMI （Linear Matrix Inequality） characterizations are further generalized to cope with the robust analysis for convex polytopic uncertain system. Robust state-feedback controller synthesis conditions are also derived for this class of uncertain systems. Using the above results, multi-objective state-feedback controller synthesis procedures which involve the LMI optimization technique are developed and less conservative than the existing one. An illustrative example verified the validity of the approach.     

Multi-objective robust controller synthesis for discrete-time systems with convex polytopic uncertain domain

Multi-objective robust state-feedback controller synthesis problems for linear discrete-time uncertain systems are addressed. Based on parameter-dependent Lyapunov functions, the Gl2 and GH2 norm expressed in terms of LMI (Linear Matrix Inequality) characterizations are further generalized to cope with the robust analysis for convex polytopic uncertain system.Robust state-feedback controller synthesis conditions are also derived for this class of uncertain systems. Using the above results,multi-objective state-feedback controller synthesis procedures which involve the LMI optimization technique are developed and less conservative than the existing one. An illustrative example verified the validity of the approach.     

长前导时间企业投入产出过程的建模与控制

研究了在经济全球化的环境下长前导时间对于企业投入产出过程的影响,阐述了在前导时间长的情况下,汇率、物价、市场等因素对于企业投入产出的生产要素的影响,然后在Leontief动态投入产出模型的基础上构建了包含前导时间影响的扩展投入产出模型,并基于差分方程的稳定性理论分析新的投入产出模型的稳定性问题,最后说明稳定性对于企业增长的意义.     

Input-output approach to robust stability and stabilization for uncertain singular systems with time-varying discrete and distributed delays

Based on input-output approach, the robust stability and stabilization problems for uncertain singular systemswith time-varying delays are investigated. The parameter uncertainties are assumed to be norm-bounded and the time-varying delays include both discrete delay and distributed delay. By introducing a new input-output model, the time-delay system is embedded in a family of systems with a forward system without time delay and a dynamical feedback uncertainty. A sufficient and necessary condition, which guarantees the system regular, impulse-free and stable for all admissible uncertainties, is obtained. Based on the strict linear matrix inequality, the desired robust state feedback controller is also obtained. Finally, a numerical example is provided to demonstrate the application of the proposed method.     

具有测量数据丢失的鲁棒H2/H∞滤波新方法

针对一类具有测量数据丢失的不确定离散随机系统,讨论鲁棒H2/H∞滤波器的问题.文章的目的是应用一种新的方法设计滤波器,使得对于所有可能的测量数据丢失和所能容许的不确定性,滤波误差系统都是均方意义下指数稳定,且同时具有H2/H∞性能特性.利用线性矩阵不等式(LM I)的方法给出满足给定性能的滤波器存在的充分条件.并通过数值仿真和对比结果验证了所提出算法的可行性.     

专业学位研究生实习基地建设需求与融合点分析

对专业学位研究生实习基地建设需求与融合点进行了分析,从学校、企业和学生3个角度分析了各自的需求,得出人才和技术是3方的主动需求点,具有较高的融合度,并可拉动与被动需求的融合。以该校物流工程研究生实习基地建设为案例,介绍了"顺丰班"订单式培养实践教学模式和"顺丰"研究生示范性实习基地建设取得的成效。     

变质量系统功能原理的转动类比与相对论形式

给出了变质量系统功能原理的转动形式与相对论形式。     

Dynamic simulation and optimal control strategy for a parallel hybrid hydraulic excavator

The primary focus of this study is to investigate the control strategies of a hybrid system used in hydraulic excavators. First, the structure and evaluation target of hybrid hydraulic excavators are analyzed. Then the dynamic system model including batteries, motor and engine is built as the simulation environment to obtain control results. A so-called multi-work-point dynamic control strategy, which has both closed-loop speed PI （proportion integral） control and direct torque control, is proposed and studied in the simulation model. Simulation results indicate that the hybrid system with this strategy can meet the power demand and achieve better system stability and higher fuel efficiency.     

丽江“大玉龙”旅游景区客源需求时间结构定量研究

旅游客源市场是旅游研究的重要组成部分之一,系统分析旅游客源市场的时间分布规律,有助于为旅游管理部门及旅游企业提供决策依据和理论支持.以丽江“大玉龙”旅游景区为例,针对其旅游客源市场的现状,用时间强度指数、高峰指数作为主要指标进行聚类分析,找出其旅游需求的时间结构规律,有助于丽江大玉龙旅游景区进一步开拓旅游市场,对其旅游规划和经营决策具有较大的现实意义.     

Dynamic modelling and robust current control of wind-turbine driven DFIG during external AC voltage dip

INTRODUCTION Due to concerns about emissions from fossil fuels and the depletion of fossil fuel resources, re- newable energy systems are becoming a topic of great interest and investment in the world. In particular, wind energy has been the subject of much recent research and development. In order to overcome the problems associated with fixed-speed wind-turbine system and to maximize the wind energy capture, many new wind farms will employ wind turbines based on Doubly-Fed Induction Ge…     

Norm-referenced,Criterion-referenced,and Dynamic Assessment: What exactly is the point?

Assessment of individual children and young people has remained a major focus of professional activity for educational psychologists (EPs) and one surrounded by continuing controversy. Despite the arguments of the 'reconstructing movement' of the 1970s, and ensuing debates, individual assessment has survived seemingly as strong as ever. Subsumed within arguments concerning the prominence given to individual assessment, another set of discussions has concerned the paradigms from which such professional activity might derive. Located among constructs contrasting environment with individual and static with interactive perspectives, the particular debate within individual assessment has centred on the relative merits of norm-referenced, criterion-referenced, curriculum-based and dynamic methods. This article presents a taxonomy of purposes and procedures deriving from these major assessment paradigms. This collection is illustrated by examples taken from EP reports, and the relative familiarity and use of each approach by one major audience group is evaluated through examining questionnaire responses from 59 Special Educational Needs Coordinators within one Local Education Authority.     

带死区非线性输入的未知混沌系统控制

针对具有死区非线性输入的未知混沌系统的控制问题,基于Lyapunov稳定性理论建立变结构模糊自适应控制器及系统参数的自适应规则。控制器的设计过程中无需知道未知非线性未知函数的上界及非线性控制输入的增益衰减度,该方法能有效消除死区非线性输入对系统的影响,并能保证闭环系统所有信号一致有界,跟踪误差渐近收敛到原点的一个可调邻域内。数值仿真的结果也验证了该方法的有效性。     

基于传染病扩散规律和聚类分析的动态疫苗配送模型（英文）

针对当传染病发生时医药物资的配送对于应急需求响应至关重要这一特点,以在一定区域内发生传染病疫情为研究背景,根据传染病扩散规律和疫区紧急救助程度的不同,研究了具有多个疫区和多个应急配送中心的疫苗配送最优方案.引入具有脉冲接种的SIQR模型来描述传染病的扩散规律和获得各区域疫苗需求量,在SIQR模型的基础上,利用SOM神经网络将各疫区进行聚类并量化结果.以实现运输成本和缺货量最小为目标,在聚类的基础上建立了动态的疫苗配送模型.以20个受感染区域和4个分布中心为例,给出了算例和仿真分析,结果表明所提出的方法有助于控制具有较高紧急等级区域的疫情,且与不使用聚类方法进行疫苗配送相比,利用聚类方法能更好地控制疫情扩散.     

Dynamic voltage regulation and power export in a distribution system using distributed generation

The major aim of power quality （PQ） enhancing techniques is to maintain a specified voltage magnitude at a desired frequency for sensitive loads irrespective of faults on the power distribution network. The dynamic voltage restorer （DVR） is a device used to mitigate voltage sags to regulate load voltage. This paper presents a mathematical model for leading series voltage injection to mitigate sags thereby achieving the improvement of the utility power factor as well as power sharing between the DVR and utility. The power sharing will be as per requirement to compensate the sags considering the available distributed generation （DG）. The approach of mitigating voltage sags using the concept of leading series voltage injection is suitable for those locations where phase shift in the voltage will not cause any problem. The MATLAB/SIMULINK SimPowerSystem toolbox has been used to obtain simulation results to verify the proposed mathematical model.     

特殊点与三角函数的图象和性质

矛盾的普遍性寓于特殊性之中。灵活运用已知条件中的特殊点 ,可以巧妙地解决三角函数图象与性质中的以下几类常见问题。1　与三角函数图象变换的位移有关的问题关于三角函数图象变换的位移 ,只需抓住图象的“起点”变化。这类题多以选择填空的形式出现。一般地 ,在“五点法”作图时 ,与ωｘ φ =0所对应的点( -φω ,0 ) ,通常称“起点”。例 1　把函数 ｙ =ｓｉｎ2ｘ ｃｏｓ2ｘ的图象适当变动可以得到 ｙ =ｓｉｎ2ｘ -ｃｏｓ2ｘ的图象 ,这种变动可以是沿ｘ轴 (　　 )(Ａ)向左平移 π3　　　 (Ｂ)向右平移 π4(Ｃ)向左平移 π2 　　　 (Ｄ…