On the synthesis of time‐varying LQG weights and noises along optimal control and state trajectories

A general approach to control non‐linear uncertain systems is to apply a pre‐computed nominal optimal control, and use a pre‐computed LQG compensator to generate control corrections from the on‐line measured data. If the non‐linear model, on which the optimal control and LQG compensator design is based, is of sufficient quality, and when the LQG compensator is designed appropriately, the closed‐loop control system is approximately optimal. This paper contributes to the selection and computation of the time‐varying LQG weighting and noise matrices, which determine the LQG compensator design. It is argued that the noise matrices may be taken time‐invariant and diagonal. Three very important considerations concerning the selection of the time‐varying LQG weighting matrices are turned into a concrete computational scheme. Thereby, the selection of the time‐varying LQG weighting matrices is reduced to selecting three scalar design parameters, each one weighting one consideration. Although the three considerations seem straightforward they may oppose one another. Furthermore, they usually result in time‐varying weighting matrices that are indefinite, rather than positive (semi) definite as required for the LQG design. The computational scheme presented in this paper addresses and resolves both problems. By two numerical examples the benefits of our optimal closed‐loop control system design are demonstrated and evaluated using Monte Carlo simulation. Copyright © 2005 John Wiley & Sons, Ltd.     

Design and conduct of occupational epidemiology studies: I. Design aspects of cohort studies

Cohort and case-control studies are two standard approaches for investigating the etiology of occupational diseases. This paper, which is the first of a four-part series, contains a review of the design features of occupational cohort studies. Topics discussed include the basic features of prospective and historical cohort studies, options for defining the cohort, disease incidence ascertainment, and considerations involved in planning an occupational cohort study. Subsequent papers in this series will focus on data analysis of occupational cohort studies and the design and analysis of occupational case-control studies.     

外语多媒体软件界面设计的认知策略模式

外语学习软件界面的设计除了应注意实现软件功能的技术因素、表现媒体的物理性状以及信息内容的学科把握 ,还应对软件界面的内容组织方略、交互通达方式、语用认知功能等方面提出要求。界面设计的出发点 ,应该是学生、学习任务及其相应的学习活动。应该根据需求分析、学习者分析、任务和内容分析来确定目标和步骤。外语教学应以语言能力、交际能力、学习策略能力为目标 ,界面设计应以此为据选择表现媒体、结构层次、交互方式和技术手段。     

The logical structure and validity of experimental designs in pharmacokinetics and clinical pharmacology

Much of the literature on research design in clinical pharmacology and pharmacokinetics emphasizes statistical concerns, thus suggesting that a primary ingredient of a valid research design is an appropriate plan for statistical analysis of data. However, statistical validity is only one of several ways to evaluate an experimental study. The present paper reviews the underlying logic and sources of invalidity of experimental drug research suggesting influences and factors which may deceive or lure an experimenter into erroneous conclusions.     

Polynomial matrix solution of H2 optimal control problem for state‐space systems

A polynomial matrix solution to the H₂ output feedback optimal control problems is obtained for systems represented in state‐equation form. The proof does not invoke the separation principle but is obtained in the z‐domain. The cost function includes weighted states, which allows the so‐called standard system model problem to be solved. This encompasses the class of inferential control problems. The results also enable the two‐degree‐of‐freedom optimal control solution properties to be explored. Copyright © 2002 John Wiley & Sons, Ltd.     

维胺酯-β-环糊精包合物的研究

应用３因素８水平的均匀设计方法，优化出维胺酯－β－环糊精包合物最佳制备条件，所得包合物的包合率为９９．３％，其表观稳定常数为１３９４Ｍ－１．     

有效中药复方研究的方法学探讨

从化学的角度探讨了临床有效中药复方研究的四个过程 ,简述了直接试验设计在全方药味筛选及化学模式识别中药质量控制中的应用 ,论述了复方有效部位和有效部位中主要有效成分的确定及化学计量学的应用和主要药效物质化学结构信息的计算机模拟方法 ,为中药复方研究提供一个范例。     

自行下体负压训练器的研制

目的 研制一种自行下体负压训练器。方法 自行下体负压训练器由若干环形钢圈及涂胶布材料构成的密闭完整的空腔壳体，可上下随意伸缩。上表面安装有单向排气阀门、可调进气阀门、把手及肩带。沿筒体纵轴进行屈／伸膝关节运动，使之被动扩张产生负压。结果 进气阀门完全关闭、打开1／4、1／2至完全打开时，训练器负压峰值逐渐降低，分别为-58、-46、-38和-26mmHg。结论 自行下体负压训练器集体育锻炼和下体负压于一体，安全可靠，使用方便，可望应用于对抗失重生理影响和飞行员抗荷生理训练。     

用正交试验法探讨芸杞补肾口服液的生产工艺

作者采用正文试验法，以水提醇沉法提取和分离酚戒类有效成分，并以苯乙醇成含量作为含量测定指标，考察了乙醇浓度、提取温度及煎煮时间三个因素对有效成分提取量的影响，从而筛选出芸杞补肾口服液的是佳生产工艺。