风险决策背景下的预警原则争议及启示

风险预警原则能否作为风险评估中的决策规则一直存在争议。尽管表述不确定性和决策专断性成为风险预警原则主要缺陷,但在风险不确定情形下,以科学为基础的评估方法却导致理性悖论。风险评估的社会建构性,揭示出风险预防是一个多元、开放、协商的过程。风险预警原则的政策含义在于,将风险不确定性这一难题转换为可以协商的话题,以形成共识。     

全球化背景下的制造业生产调度体系探讨

面对客户随机需求,制造业生产调度系统应促进生产的快速性、动态性和敏捷性。论文以制造业生产调度体系为研究对象,从生产车间调度的目标、方法、手段、资源等基本要素入手,总结了传统生产调度系统在实际生产中的问题,并概括了系统集成视角下的生产调度方法及其改进措施,介绍了不确定条件下生产调度策略及评价指标。运用系统集成的思想,探讨了供需链环境下的制造业生产调度系统模式,最终提出了生产调度系统的集成化、动态化、高效智能化、柔性化和排程可视化等发展方向。     

多时滞非线性系统的鲁棒非脆弱H_∞控制

针对一类不确定多时变时滞非线性系统,探讨了鲁棒非脆弱H∞控制器的设计问题.假定其中的不确定性是范数有界的,并且系统的状态是完全可测的,利用李亚普诺夫稳定性方法,以线性矩阵不等式的形式,给出了使该不确定多时变时滞非线性闭环系统渐近稳定及非脆弱鲁棒H∞状态反馈控制器存在的充分条件.通过求解相应的线性矩阵不等式就可得到系统的非脆弱鲁棒H∞控制器,同时也能保证从扰动到受控输出之间传递函数的H∞范数不大于给定的指标值.数值算例验证了所给方法的有效可行性.     

一类不确定非线性系统的参数自适应滑模控制

针对一类具有不确定性的非线性系统,考虑参数摄动、未建模动态和外界干扰等各种不确定性的综合影响,提出了一种基于切换增益和sigmoid函数边界层厚度的参数自适应滑模控制策略,采用李雅普诺夫稳定性理论证明了闭环系统全局稳定性.该控制方法消除了传统滑模控制的输入抖振现象,而且跟踪精度高,无须确知不确定项的界.仿真算例验证了该方法的有效性.     

可修复产品逆向物流网络的鲁棒优化模型研究

考虑一类同时具有回收、再处理、处理和废物处理中心的可修复产品逆向物流网络在产品回收率不确定环境下的网络优化问题.为了提高可修复产品逆向物流网络的经济效益和网络的稳健性,建立了可修复产品逆向物流网络在产品回收率不确定情况下的鲁棒优化模型,分析了鲁棒优化模型解的存在性.     

不确定OD需求下的轴-辐式集装箱海运网络设计

从轴-辐式集装箱海运网络设计角度出发,深入分析港口节点、航段节线和集装箱OD三个要素的相互关系,考虑到集装箱OD需求的不确定性对轴-辐式集装箱海运网络设计的影响,利用随机规划方法,建立不确定OD需求下的轴-辐式集装箱海运网络优化模型,借助机会约束规划将其转化为确定性等价模型;结合贪婪算法改进禁忌搜索算法对模型进行求解。研究结果表明:禁忌长度的增大将降低算法的效率;随机模型比确定模型具有成本优势;改进禁忌搜索算法具有更快的收敛速度和更准确的求解精度。     

High-order sliding mode attitude controller design for reentry flight

A novel high-order sliding mode control strategy is proposed for the attitude control problem of reentry vehicles in the presence of parametric uncertainties and external disturbances, which results in the robust and accurate tracking of the aerodynamic angle commands with the finite time convergence. The proposed control strategy is developed on the basis of integral sliding mode philosophy, which combines conventional sliding mode control and a linear quadratic regulator over a finite time interval with a free-final-state and allows the finite-time establishment of a high-order sliding mode. Firstly, a second-order sliding mode attitude controller is designed in the proposed high-order siding mode control framework. Then, to address the control chattering problem, a virtual control is introduced in the control design and hence a third-order sliding mode attitude controller is developed, leading to the chattering reduction as well as the control accuracy improvement. Finally, simulation examples are given to illustrate the effectiveness of the theoretical results.     

Ranking grey numbers based on dominance grey degrees

With respect to the decision making problems where a lot of fuzzy and grey information always exists in the real-life decision making information system methods as fuzzy mathematics, it is difficult for such uncertainty probability, and interval numbers to deal with. To this end, based on the thought and method of grey numbers, grey degrees and interval numbers, the concept of dominance grey degree is defined. And then a method of ranking interval grey numbers based on the dominance grey degree is proposed. After discussing the relevant properties, the paper finally uses an example to demonstrate the effectiveness and applicability of the model. The result shows that the proposed model can more accurately describe uncertainty decision making problems, and realize the total ordering process for multiple-attribute decision-making problems.     

LIVESTOCK PRODUCTION PLANNING UNDER ENVIRONMENTAL RISKS AND UNCERTAINTIES

1. Introduction The world food economy is increasingly being driven by a shift of diets towards livestock products. In the developing countries, consumption of meat has been growing at 5-6 percent p.a., and that of milk and dairy products at 3.3-3.5 percent p.a. in the last few decades. Much of the growth is taking place in China (Huang and Zhang et al. 2003a, Huang and Liu 2003b, Keyzer and van Veen 2004, Ma and Huang et al. 2004, Simpson and Cheng et al.1994, USDA Economic Research Se…     

网络化服务组织的效率和福利改进分析

售后服务行业在我国东部一些大城市已经逐步向网络式组织转化,这种组织形式的业量具有不确定性特点,从学术界已有的研究中难以找到对这种组织形式经济学特性的深入研究.就其面对的市场特点建立了泊松流模型对网络化服务组织进行分析,得出网络化服务组织的效率改进主要体现在资产和管理的规模经济及不确定条件下的人员互补效应,后者是和不确定性相联系的一种规模经济.这种组织形式对所涉及各方均带来了有利的影响,是市场效率提高的表现.