时滞系统的预测控制及其仿真分析

针对PID对大滞后大惯性系统的控制效果不佳、参数整定复杂等方面的不足,将预测控制应用到时滞控制系统当中,并在MATLAB环境下进行仿真。以算例证明预测控制应用于时滞控制系统中,比单纯的HD控制具有更良好的鲁棒性和抗干扰性,不但调节速度更快,参数整定方法更简单,而且还不依赖于对象模型的参数,非常适用于工业过程控制。     

UPS系统中PWM整流器的研究

针对传统UPS电源系统在低压时电压利用率低、谐波大的缺点,提出一种双闭环参数整定的方法,该方法将传统单相电压型PWMUPS系统改进为双闭环系统的参数整定方案,采用电流内环、电压外环相结合的双闭环控制方式,再通过理论分析、建模和仿真,最终达到系统功率因数接近于1的目的;仿真结果与理论分析的结果基本相同,验证了此方法的正确性和可行性。     

基于座椅安全带固定点试验台的液压伺服系统性能分析

基于汽车座椅安全带固定点试验台对液压伺服闭环控制系统进行了分析。解析了系统结构主要组成部分,建立系统数学模型。根据控制原理分析了系统的稳定性和稳态性能,对调节器PID参数进行整定,通过对实测波形和仿真波形的比较表明模型及其参数的正确性。     

基于SIMULINK对非线性系统死区环节进行仿真

主要是针对非线性系统死区环节进行SIMULINK仿真,通过仿真分析来实现控制系统的优化。本文介绍了MATLAB中SIULINK工具的应用,对控制系统非线性环节的死区环节的分析,并用SIMULINK进行仿真解析的过程。     

基于遗传算法的模糊自抗扰PID双环直流调速系统

本文将遗传算法与模糊控制相结合,针对工程上通常采用直流调速系统,详细分析双闭环调速系统的模糊自整定PID控制,设计了模糊控制器并对直流双闭环调速系统进行建模,分别对系统的电流环、转速环的动态性能、抗干扰性能进行仿真分析,最后,与传统PID控制进行比较,可见模糊自整定控制可以大大提高控制效果、增强抗扰性能、加快系统响应速度快,具有良好的动态性能。     

双直线电机往复泵恒流控制的研究

双直线电机往复泵与传统往复泵相比,具备结构简单、冲程长、冲次低、排量波动小、泵压均匀和系统效率高等一系列优点,是一种非常具有发展潜力的新型往复泵。文章介绍了直线电机的工作原理,并利用模糊PI控制实现了双直线电机的协调控制,从而在理论上实现了双直线电机的恒流输出。并通过建立控制系统的MATLAB/SIMULINK仿真模型,验证此方法的有效性和可行性,从而为实际的直线电机控制打好理论基础。     

经典控制理论在飞行控制系统中的设计应用

飞行控制系统对控制飞机起到了至关重要的作用。飞行控制系统可用来保证飞行器的稳定性和操纵性、提高完成任务的能力与飞行品质、增强飞行的安全及减轻驾驶员负担。然而如何设计闭环飞行控制系统的反馈参数,使此系统能拥有良好的动态特性和飞机控制力。本文以F16飞机模型为例,以经典控制理论中的根轨迹法为切入点,运用MATLAB软件进行仿真分析设计,最终设计闭环飞行控制系统的反馈参数。     

基于无功功率模型的MRAS辨识异步电机转子时间常数方法

本文针对异步电机矢量控制系统控制精度不高的问题,对影响异步电机矢量控制效果的异步电机转子时间常数整定策略进行了研究,介绍了一种基于无功功率模型的MRAS辨识异步电机转子时间常数方法,并对该策略进行了MATLAB仿真,仿真结果表明,该方法能有效降低转子磁链观测误差,抑制转矩脉动,提高控制系统性能。     

基于MATLAB的永磁同步电机矢量控制系统仿真

根据永磁同步电机（PMSM）的数学模型及矢量控制方法,在MATLAB／SIMULINK环境中建立独立的功能模块,对电机及其控制系统的各部分进行建模,并进行了仿真分析。     

模糊控制的逆变器仿真研究

文章以电压型逆变电路作为被控对象,采用双闭环控制系统对其进行控制,以输出得到理想的正弦交流电压波形。用MATLAB进行仿真实验,结果证明了这种智能控制系统性能良好,是一个能达到满意控制效果的设计。     

Development in Information and Communications Technology (ICT) Statistics at the Australian Bureau of Statistics

This paper outlines the ICT statistical developments that the ABS has undertaken over recent years. These developments have been on both the supply side (ICT industry) and the demand side (use of IT by sector). The content of ABS ICT surveys has changed significantly over the last few years and are expected to develop further in line with industry changes and emerging policy needs.
Recent developments in household collections have been the inclusion of IT use questions in the 2001 Census of Population and Housing and in various ABS social surveys such as Children's Participation in Culture and Leisure Activities. Annual business IT use surveys are now conducted and include topics such as Internet commerce and IT security. Biennial ICT industry surveys are conducted to provide data on ICT production, imports and exports, ICT industry employment, performance and structure information. An Internet activity survey is run every six months and provides regional Internet access details and infrastructure details on Internet service providers.
A major development for 2002–03 will be the compilation of an ICT satellite account. ABS intends to produce an ICT Information Development Plan to guide its future statistical development work in the ICT field.     

Value at Risk in the Suburbs: Eminent Domain and the Geographical Politics of the US Foreclosure Crisis

Several US counties and local governments have recently considered a novel solution to the foreclosure crisis. They plan to use eminent domain to compel the owners of mortgage debt—and specifically of private‐label mortgage‐backed securities—to sell the debt to the government at a price reflecting the loan's market value. The government would then restructure the debt and resell it to new investors. The plans are striking because—in contrast to both development‐driven eminent domain and the federal subprime bank bailout—they would force investors to assume asset devaluation and increased long‐term risk. Notably, the plans have emerged as an instance of financialization‐focused politics in suburbs and suburban cities of color, specifically majority‐black and ‐Latino/a suburbs. Local support for the plans, we argue, is rooted in the long‐term disinvestment of these ‘suburbs of exception', which became targets of subprime lending and eventually sites where the ‘financial exception' has been localized. But these demographic shifts, fragmentation and fiscal pressures have at the same time created a suburban political terrain in which the plans have gained their strongest political support.     

Towards a Theory of Serendipity: A Systematic Review and Conceptualization

Serendipity – the notion of making surprising and valuable discoveries – plays a major role in the success of individuals and organizations alike. Previous research has established the importance of serendipity and identified important individual- and organizational-level antecedents. However, the literature has been dispersed and the boundaries of the concept have been blurry, leading to a lack of conceptual clarity and structure, and thus limiting validity and managerial actionability. Based on a systematic literature review, I synthesize existing management-related research on serendipity and explicate the emergence and composition of serendipity in the organizational context. I first identify three necessary conditions that differentiate serendipity from related concepts such as luck or targeted innovation: agency, surprise, and value. Then, I draw from the literature on sensemaking, event-based theorizing, and quantum-based approaches to management to conceptualize the process of cultivating serendipity in the organizational context as a process of enabling potentiality and materialization, and develop a multi-level theory of (cultivating) serendipity. This conceptualization contributes to our collective understanding of how, why, and when (i.e., under what conditions) organizations can leverage the value in the unexpected, which opens up fruitful avenues for further research.     

Accountability of NGOs in Bangladesh A critical overview

NGOs in Bangladesh have been recognized as effective change agents in the socio-economic arena throughout the world. Their contributions in micro credit, non-formal education and primary health care are widely known. NGOs play a significant role in society. NGO accountability, as a result, has become a critical issue. NGO accountability in Bangladesh has been examined here in relation to patrons, clients and themselves. Of the three relationships only accountability to patrons is in a near satisfactory state. Accountability to clients is handicapped by lack of opportunities of beneficiaries to participate meaningfully in NGO policy making. Accountability to themselves is adversely affected due to the adherence to a strictly hierarchical system and the influence of founding and charismatic NGO leaders.     

Towards an Asian model of human resource management? A comparative analysis of China,Japan and South Korea

There has been much discussion regarding the possible decline and weakening of national systems of human resource management (HRM). Yet, culture and institutions are often cited as the major stumbling blocks to this outcome. Such constraints may dissipate in the analysis, particularly if ‘regional clusters’ are considered where geographic and cultural closeness and ‘openness’ to similar economic pressures exist. In such cases, it might be postulated that convergence in HRM will occur. We argue that China, Japan and South Korea represent such a cluster. This article examines these countries, to see if a degree of convergence is taking place and if it is towards an identifiable ‘Asian’ model of HRM. A model of change is presented that distinguishes between levels of occurrence and acceptance. Details of the development and practice of HRM in each country are then set out. The article ends with a discussion and implications section and a brief conclusion.     

Ansätze und Ergebnisse anglo-amerikanischer M&A-Forschung

Based on a review of established U.S. management journals (1995–2003), six schools of thought are identified within the Anglo-American M&;A research: “Capital Market”, “Principal/Agent”, “Industrial Organization”, “Organizational Behavior”, “Human Resources” and “Strategic Management”. The literature review shows that the definition of M&;A success, the methods applied, and insights from empirical research differ according to the respective school of thought. Empirical studies focus on the resource combinations of merger partners, the specific circumstances of merger negotiations, and on integration management as antecedents of merger performance. Unfortunately, empirical findings have not yet provided reliable explanations for M&;A success. Based on the current state of Anglo-American M&;A research, the authors discuss implications for business practice, identify research gaps, and propose areas for future research.     

Introduction of New Technology with a Sound Transition of the Input-Output Structure

We examine the general equilibrium repercussions associated with the introduction of new technologies, using the generalized Leontief system that allows technological substitutions. We show that an untested introduction of cost-increasing technologies in any industry may result in creating a non-productive technological structure that does not satisfy the Hawkins-Simon condition, following the autonomous dynamic adjustment process with structural transitions in the economic system. Therefore, we propose a practicable control scheme of introducing cost-increasing technologies that strictly avoids the creation of non-productive structures in all periods of structural transition, using the available information on the ex ante technological structure.     

The Creation of the Office for National Statistics

A new Office for National Statistics was created in the United Kingdom in 1996 following a series of developments designed to strengthen the relevance and integrity of statistics. This paper describes these fundamental changes and sets out a blueprint for future progress. It also sets current developments in the United Kingdom in an historical and international context.     

What helps? Women engineers' accounts of staying on

We have considerable understanding of the obstacles that women engineers encounter and the reasons that they leave the field, but we know less about what enables them to remain. Adopting an interpretivist approach, this article examines how a group of British women engineers in two FTSE 100 companies account for “staying on” in their male‐dominated work settings. We delineate four specific forms of help that facilitate women's retention in the field. We argue that exposure to help leads to women developing a habitus that enables them to continue working in engineering. To conclude, we draw on our findings to outline HR practices that will facilitate supportive relationships in the workplace and pave the way towards developing more positive organisational climates.     

论现代物流企业的发展观

物流业经过诸多年的发展目前已经成为最热门的行业之一,物流企业的注册数量也与日俱增,达到前所未有的规模。毋庸置疑,任何企业都希望自己迅速做强做大,并成为真正现代物流企业的典型代表,要实现这一目标一个首要问题就是要解决现代物流企业的发展观问题。