ROBUST GUARANTEED COST CONTROL OF UNCERTAIN NON-LINEAR ROBOTIC SYSTEM USING MIXED MINIMUM TIME AND QUADRATIC PERFORMANCE INDEX

To provide better transient performance in controlling robots, a mixed minimum time and quadratic performance index is used. For known and uncertain revolute robot manipulators a conventional optimal control and a robust guaranteed cost control are proposed respectively. Asymptotic stability is also discussed based on the Lyapunov direct method. The proposed robust control is continuous and requires no knowledge of the uncertain system except for bounding functions.     

乳房手术中喉罩通气压力与容量控制呼吸模式的比较

目的:比较乳房手术喉罩通气压力控制呼吸(PCV)与容量控制呼吸(VCV)模式对心血管、气道压力与漏气率的影响。方法:30 例全麻下行乳房手术患者,年龄46．05±4．32岁,ASA Ⅰ-Ⅱ级,静脉麻醉诱导后置入喉罩,按随机顺序接受PCV和VCV两种通气方式,通气期间保持相同的呼气末二氧化碳分压(PetCO2)达到30-40mmHg,并稳定15min后分别记录呼吸循环参数。结果:两种通气方式SBP、DBP、HR、PetCO2、SPO2比较无显著差异,P>0．05。PCV时气道峰压和漏气率明显低于VCV,P<0．05,VCV期间有6例气道峰压大于20cmH2O,而PCV期间有3例为20cmH2O,15min后P-V环的密闭性PCV通气方式优于VCV期间。结论:全麻喉罩通气期间PCV较VCV方式能在较低的压力下提供有效的肺通气,是较为理想和安全的通气模式。     

一类不确定混杂动态系统的保性能控制及其应用

考虑在汽车自动变速巡航控制中遇到的、包含状态跳变的参数不确定混杂系统保性能控制问题，提出了混杂状态反馈保性能控制律的设计方法，该控制律在使不确定混杂系统闭环鲁棒稳定的同时，也使其性能满足一定要求。最后用实例验证了设计方法的可行性和有效性。     

Oxygenation remains unaffected by increased inspiration-to-expiration ratio but impairs hemodynamics in surfactant-depleted piglets

Objectives Prolongation of inspiratory time is used to reduce lung injury in mechanical ventilation. The aim of this study was to isolate the effects of inspiratory time on airway pressure, gas exchange, and hemodynamics, while ventilatory frequency, tidal volume, and mean airway pressure were kept constant.Design Randomized experimental trial.Setting Experimental laboratory of a University Department of Anesthesiology and Intensive Care.Animals Twelve anesthetised piglets.Interventions After lavage the reference setting was pressure-controlled ventilation with a decelerating flow; IE was 11, and PEEP was set to 75% of the inflection point pressure level. The IE ratios of 1.51, 2.31, and 41 were applied randomly. Under open lung conditions, mean airway pressure was kept constant by reduction of external PEEP.Measurement and results Gas exchange, airway pressures, hemodynamics, functional residual capacity (SF₆ tracer), and intrathoracic fluid volumes (double indicator dilution) were measured. Compared to the IE of 11, PaCO₂ was 8% lower, with IE 2.31 and 41 (p0.01) while PaO₂ remained unchanged. The decrease in inspiratory airway pressure with increased inspiratory time was due to the response of the pressure-regulated volume-controlled mode to an increased IE ratio. Stroke index and right ventricular ejection fraction were depressed at higher IE ratios (SI by 18% at 2.31, 20% at 41; RVEF by 10% at 2.31, 13% at 41;p0.05).Conclusion Under open lung conditions with an increased IE ratio, oxygenation remained unaffected while hemodynamics were impaired.This study was supported by the Swedish Medical Research Council (project 4252), the Swedish Heart-Lung Foundation, Stockholm, Sweden, and the Laerdal Foundation for Acute Medicine, Stavanger, Norway     

Optimal guaranteed cost stabilization of networked systems with bounded random packet losses

This paper is concerned with the optimal guaranteed cost stabilizing controller design problem for a class of networked control systems (NCSs) with random packet losses. The number of consecutive packet losses is assumed to be upper bounded, and the closed‐loop NCS is described as a discrete‐time stochastic delay system with a time‐varying input delay and a stochastic parameter. A sufficient condition is derived for the closed‐loop NCS to be exponentially stable and achieve an optimal guaranteed cost performance level. The relationships among the exponential decay rate, the guaranteed cost performance level, and two parameters characterizing the random packet losses, namely, the packet loss probability and the maximal number of consecutive packet losses, are simultaneously established in the obtained condition. Furthermore, design procedures for the state feedback stabilizing controllers are also presented. Finally, an illustrative example is given to show the effectiveness of the proposed results. Copyright © 2011 John Wiley & Sons, Ltd.     

压力控制法肺复张在急性呼吸窘迫综合征中的应用

机械通气是急性呼吸窘迫综合征(ARDS)的主要治疗手段,肺复张手法应用较高压力开放塌陷肺泡,并使用高呼吸末正压防止肺泡塌陷,期望恢复肺泡的同一性,减少呼吸机相关性肺损伤,改善患者预后。但近年的临床试验却得出矛盾的结果,其有效性及安全性及具体实施方法仍无统一意见。现就压力控制法肺复张在ARDS中的有效性、安全性的操作方法予以综述。     

不同通气模式对单肺通气影响的Meta分析

目的 采用Meta分析的方法评价压力控制通气(pressure controlled ventilation,PCV)与容量控制通气(volume controlled ventilation,VCV)对术中单肺通气(one lung ventilation,OLV)患者呼吸力学及循环的影响. 方法 检索PubMed、Embase、Cochrane图书馆,检索时间从建库至2016年2月.收集术中OLV使用PCV与VCV的临床随机对照试验(randomizedcontrolled trim,RCT).采用Cochrane协作网系统评价法评价纳入文献的质量,采用RevMan 5.0软件对收集的患者资料进行Meta分析评价. 结果 共纳入14项研究,包括964例患者,其中PCV组480例,VCV组484例.与VCV组比较:在开胸前双肺通气时(T1),PCV组气道平均压(mean airway pressure,Pmean)比值比(odds ratio,OR)[0R=-0.22,95％CI(-0.42,-0.01),P＜0.05]较低;OLV时(T2),PCV组气道峰压(peak airway pressure,Ppeak)[加权均数差(weighted mean difference,WMD)=-1.37,95％CI(-1.69,-1.05)]及气道平台压(pause pressure,Plateau)较低[WMD=-0.29,95％CI(-0.51,-0.07)],而PaO2高[WMD=0.52,95％CI(0.08,0.95)];关胸后双肺通气时(T3),PCV组Ppeak较低[WMD=-0.63,95％CI(-1.09,0.17)]. 结论 与VCV比较,OLV期间PCV可提供较低的气道压,可能是一种较好的通气模式.     

Guaranteed cost control for switched LPV systems via parameter and state‐dependent switching with dwell time and its application

This paper is concerned with the problem of guaranteed cost control for switched linear parameter‐varying (LPV) systems. A parameter and state‐dependent switching law with dwell time is designed. The guaranteed cost control problem for switched LPV systems is still solvable even though this problem for each subsystem is unsolvable. First, a sufficient condition ensuring the solvability of the guaranteed cost control problem for switched LPV systems is presented via multiple parameter‐dependent Lyapunov functions. Then, the parameter‐dependent controller is designed, such that the closed‐loop system is asymptotically stable with the guaranteed cost index. Finally, the effectiveness of the proposed control design scheme is illustrated by its application to an aero‐engine. Copyright © 2016 John Wiley & Sons, Ltd.     

Robust inventory‐production control problem with stochastic demand

This paper deals with the inventory‐production control problem where the produced items are supposed to be deteriorating with a rate that depends on the stochastic demand rate. The inventory‐production control problem is formulated as a jump linear quadratic control problem. The optimal policy that solves the optimal control problem is obtained in terms of a set of coupled Riccati equations. The guaranteed cost control problem is also investigated. Copyright © 1999 John Wiley & Sons, Ltd.