Permissible control of general constrained mechanical systems

This paper develops a unified approach for modeling and controlling mechanical systems that are constrained with general holonomic and nonholonomic constraints. The approach conceptually distinguishes and separates constraints that are imposed on the mechanical system for developing its physical structure between constraints that may be used for control purposes. This gives way to a general class of nonlinear control systems for constrained mechanical systems in which the control inputs are viewed as the permissible control forces. In light of this view, a new and simple technique for designing nonlinear state feedback controllers for constrained mechanical systems is presented. The general applicability of the approach is demonstrated by considering the nonlinear control of an underactuated system.     

Control of PDE-ODE cascades with Neumann interconnections

We extend several recent results on full-state feedback stabilization and state estimation of PDE-ODE cascades, where the PDEs are either of heat type or of wave type, from the previously considered cases where the interconnections are of Dirichlet type, to interconnections of Neumann type. The Neumann type interconnections constrain the PDE state to be subject to a Dirichlet boundary condition at the PDE-ODE interface, and employ the boundary value of the first spatial derivative of the PDE state to be the input to the ODE. In addition to considering heat-ODE and wave-ODE cascades, we also consider a cascade of a diffusion-convection PDE with an ODE, where the convection direction is “away” from the ODE. We refer to this case as a PDE-ODE cascade with “counter-convection.” This case is not only interesting because the PDE subsystem is unstable, but because the control signal is subject to competing effects of diffusion, which is in both directions in the one-dimensional domain, and counter-convection, which is in the direction that is opposite from the propagation direction of the standard delay (transport PDE) process. We rely on the diffusion process to propagate the control signal through the PDE towards the ODE, to stabilize the ODE.     

Review and new evidence on composite innovation indicators for evaluating national performance

The purpose of this contribution is to present a survey of the recent developments in constructing composite science and technology (S&T) indicators on a national level as well as new evidence of the variability of such S&T indicators which opens the gateway to “country-tuning”. It has become standard practice to combine several indicators for science, technology, and innovation to form composite numbers. Especially in the light of this variability, two questions arise. Firstly, are the results (especially rankings) stable with respect to weights? Secondly, is there hope to define “economically” reasonable weights? In order to provide answers to these questions, we use data from the European Innovation Scoreboard 2005 (EIS 2005) to exemplify our reasoning. Concerning the first question, we give genuine evidence on the existence of immense variability, possibly invalidating the results. Further, we also show that even existing and well-accepted methods, like equal weighting, Benefit of the Doubt weighting (BoD) and principal component analysis weighting (PCA) may lead to drastically differing results. Concerning the second question we will demonstrate that by each composite indicator weighting a set of shadow prices is implied expressing one indicator in terms of another. Whether the weights are sensible should be evaluated on the basis of these shadow prices. It turns out that those implied by EIS 2005 contain strange peculiarities. After that we plead for more care in constructing composite indicators. Especially weights should be chosen on the basis of shadow prices, rather than, say, by equal weighting or other automatic methods. Lastly, we discuss the merit of composite indicators and argue that they have a valuable communication and competition function, but they should be accompanied by multidimensional representations, which provide the basis for the construction of policy measures.     

我国粮食生产与消费中长期情景预测及政策建议

2008年以来,一些国家粮食短缺,粮价飞涨,发生饥饿粮荒,最终导致通货膨胀和社会动荡.与此相对的是,我国粮食供求平衡,粮食自给率连续十年保持在95%以上.然而,随着我国将迎来15亿人的人口峰值对粮食需求量的巨大推动,以及城镇化率和人均收入迅速提高对人均粮食消费数量及结构的重要影响,我国粮食生产与消费在未来三五十年是否依然可以继续保持乐观形势是摆在党和政府面前的重要问题.因此,有必要根据相关影响要素,构建我国粮食生产与消费中长期变化的可能情景,在此基础上做出预测分析并提出相应的政策建议,为国家制定粮食产业政策提供参考.     

基于SOA的中国邮政信息系统集成研究

SOA能有效解决信息化环境下业务集成问题。针对中国邮政现存的各种遗留信息系统,通过将其包装成"服务"的思想,研究了一种信息系统集成方法,并结合实际给出了它的体系结构和实现框架,提出了解决中国邮政各信息系统的互操作及重用问题的对策建议。     

我国食品安全发展态势的战略情报研究

结合共词分析法与战略坐标对食品安全发展态势做战略情报分析,得到当前国内食品安全研究领域的8个热点,为进一步定量分析各热点的发展趋势绘制了战略坐标图,研究结果表明:食品卫生监督、食品安全管理及法律法规、食品安全体系建设、残留危害物质及检测是当前研究的中心内容;食物中毒及有害微生物的快速检测处于探索阶段;农产品安全及食品标准尚不成熟;食品污染和食品RFID追溯制度处于研究领域的边缘。     

企业创新:激励体系与企业创新能力关系研究

对135家企业的250名员工进行问卷调查收集数据,实证研究了激励体系对企业技术创新能力的影响。结果表明,创新价值观、创新氛围及创新激励制度与技术创新能力显著正相关,企业绩效与技术创新能力显著负相关。     

汶川地震滑坡在两个典型区域内的分布研究

汶川地震诱发了数以万计的滑坡.选择2个地震滑坡重灾区域(A/B),基于空间分析方法,对地震滑坡分布与地层岩性、坡度、高程、地震动峰值加速度以及发震断裂距离之间的关系进行统计分析.结果表明,研究区A内滑坡最易发岩组为石墨片岩、石英岩岩组,研究区B内滑坡最易发岩组为粉砂岩、砂岩、硅质岩岩组;2研究区内滑坡易发程度均随着坡度的增加而升高,A区的滑坡发生优势坡度为44°,B区为38°;滑坡发育与高程均存在一定的对应关系;滑坡分布与地震动峰值加速度没有明显的对应关系,但是与距离发震断裂具有良好的对应关系,且上盘滑坡发育程度明显高于下盘.     

新疆与国内部分省区科技体制改革实践的启示

通过对我国部分省区科技体制改革发展情况的了解以及对其改革经验的总结,结合新疆实际情况,对新疆科技体制改革提出建议。     

社会型塑食品安全的参与者分析

新技术社会学产生于上世纪80年代的欧美,它认为社会的各种参与者(actors)型塑了技术.运用这一理论视角,分析食品安全问题,生产方、监管方、消费方等社会参与者共同编织成确保食品安全的人与非人行动者的异质网络.