Stability criteria for linear systems with multiple time-varying delays

New delay-independent and delay-dependent stability criteria for linear systems with multiple time-varying delays are established by using the time-domain method. The results are derived based on a new-type stability theorem for general retarded dynamical systems and new analysis techniques developed in the author's previous work. Unlike some results in the literature, all of the established results do not depend on the derivative of time-varying delays. Therefore, they are suitable for the case with very fast time-varying delays. In addition, some remarks are also given to explain the obtained results and to point out the limitations of the previous results in the literature. Keywords Stability - Delay-independent criteria - Delay-dependent criteria - Linear time-delay systems - Multiple time-varying delays This work was supported by NSFC Key-Project (No. 60334010) and Guangdong Province Natural Science Foundation of China (No. 31406).

Delay-dependent criteria for the robust stability of systems with time-varying delay

The problem of delay-dependent robust stability for systems with time-varying delay has been considered. By using the S-procedure and the Park's inequality in the recent issue, a delay-dependent robust stability criterion which is less conservative than the previous results has been derived for time-delay systems with time-varying structured uncertainties. The same idea has also been easily extended to the systems with nonlinear perturbations. Numerical examples illustrated the effectiveness and the improvement of the proposed approach. Keywords Delay-dependent criteria - Robust stability - Time-varying structured uncertainties - Nonlinear perturbations - Linear matrix inequality This work was supported by the Doctor Subject Foundation of China (No. 2000053303).

Controller Design for a Teleoperation System with Time Delay

A robust controller design method is presented to guarantee the stability and zero tracking error for teleoperation system with time delay. Through choosing appropriate master and slave parameters, extended state equation about master and master-slave error is achieved, which can be analyzed by using time delay knowledge. Thus delay-independent and delay-dependent criteria are derived in terms of the Lyapunov stability theorem, control parameters are obtained by the feasible of linear matrix inequalities. Experimental results show the validity of these approaches and the performance of master and slave manipulators with delay variations is analyzed.

Delay-dependent exponential stability criteria for stochastic systems with polytopic-type uncertainties

This paper considers the problem of delay-dependent exponential stability in mean square for stochastic systems with polytopic-type uncertainties and time-varying delay. Applying the descriptor model transformation and introducing free weighting matrices, a new type of Lyapunov-Krasovskii functional is constructed based on linear matrix inequalities （LMIs）, and some new delay-dependent criteria are obtained. These criteria include the delay-independent/rate- dependent and delay-dependent/rate-independent exponential stability criteria. These new criteria are less conservative than existing ones. Numerical examples demonstrate that these new criteria are effective and are an improvement over existing ones.

A Production Inventory Model with Shortages, Fuzzy Preparation Time and Variable Production and Demand

A production inventory model is formulated for a single item. Here, demand varies with the on-hand inventory level and production price. Shortages are allowed and fully backlogged. The time gap between the decision and actual commencement of production is termed as “preparation time” and is assumed to be crisp/imprecise in nature. The set-up cost depends on preparation time. The fuzzy preparation time is reduced to a crisp interval preparation time using nearest interval approximation and following the interval arithmetic, the reduced problem is converted to a multi-objective optimization problem. Mathematical analysis has been made for single objective crisp model (Model-I). Numerical illustration have been made for both crisp (Model-I) and fuzzy (Model-II) models. Model-I is solved by generalized reduced gradient technique and multi-objective model (Model-II) by Global Criteria Method. Sensitivity analyses have been made for some parameters of Model-I.

Flood Risk Code Mapping Using Multi Criteria Assessment

Flash flood is a dangers natural disaster causes lots of structure damage, traffic collapse, economic defects and human life loss. An efficient way to reduce its effects is preparing flash flood mapping to identify zones at risk due to flood. Flash flood mapping is a powerful tool for urban planners, traffic and infrastructure engineers, emergency and rescue services. This article proposes an approach utilizes remote sensing (RS) and geographic information system (GIS) to prepare flood risk code (FRC) map for Jeddah city, Saudi Arabia. The proposed approach applied the Curve Number (CN) method of flood modelling and uses runoff depth, land use, soil hydrological parameters, surface slope, and longest flow path to generate FRC. SPOT satellite image of the study area was classified to generate land use map, Digital Elevation Model (DEM) was used for generating slope map and for hydrology analysis using HEC-GeoHMS tool, and soil properties were generated from scanned soil maps. All data were integrated in ArcGIS 10.4.1 to prepare the final flood risk map. The results show that a precipitation of 106.3 mm will generate 136.5 million m3 of flood water. The results according to the developed flood risk code show that due to this amount of precipitation, about 1 million people live in Jeddah are prone to extreme flood risk and about 2 million of population are at major risk, the rest of population (about 0.5 million) are vulnerable to moderate to minor fold risk. The approach was verified using ground truth data and proofed precision.

A Decision Support Framework for the Choice of Languages and Methods for the Design of Real Time Embedded Systems

The choice of methods or design languages is a crucial phase in the development of systems and software, also for real time and embedded systems. An open question that remains in the design of these types of systems is to build a method, or to choose one among those existing, capable to cover the life cycle of a project, and particularly the development phases. This article contributes to answer the question, by proposing an approach based on a multi-criteria comparative study, of few languages and methods dedicated to the design of real time and embedded systems. The underlying objective of this work is to present to designers a wide range of approaches, and elements that can guide their choices. In order to reach this goal, we propose different comparison criteria. Each criterion is divided into sub-criteria, so that the designers can refine their choices according to the qualities they prefer and wish to have in the method or language. We also define a rating scale which is used to assess the retained languages and methods. The scores obtained from this assessment are presented in tables, one table per criterion, followed by a summary table giving the overall scores. Graphics built from these tables are provided and intend to facilitate the judgement and thus the choice of the designers.

基于Apriori多维传感参量沙棘质量监测系统设计

沙棘具有很高的营养价值,常被应用于植物原料提取行业。但由于沙棘品质监测技术的缺失,导致基于沙棘制造的副产品质量难以保证。目前沙棘质量检测主要采用单一的沙棘化学成份含量检测,难以满足对沙棘品质监测的技术需求。从沙棘生长特征出发,利用无线传感网技术和多传感技术对沙棘生长环境的多维度参数进行采集传输,基于改进Apriori(先验原理)对多维传感参量特征关联规则进行数据挖掘,分析标签值,选择出较高的沙棘副产品对应的沙棘生长环境特征数据,挖掘数据特征之间存在的映射关系,作为沙棘溯源质量监测评价的参考规范。基于Spark Streaming实时数据处理技术,构建沙棘质量监测系统。通过映射规则构造条形图直观展示,便于指导沙棘原料的筛选。从沙棘副产品质量监管出发,利用优质沙棘副产品溯源环境数据构建沙棘原料质量监测体系,提高以沙棘为原料的副产品品质监管。

Delay-dependent Criteria for Robust Stability of Uncertain Switched Hopfield Neural Networks

This paper deals with the problem of delay-dependent robust stability for a class of switched Hopfield neural networks with time-varying structured uncertainties and time-varying delay. Some Lyapunov-KrasoVskii functionals are constructed and the linear matrix inequality （LMI） approach and free weighting matrix method are employed to devise some delay-dependent stability criteria which guarantee the existence, uniqueness and global exponential stability of the equilibrium point for all admissible parametric uncertainties. By using Leibniz-Newton formula, free weighting matrices are employed to express this relationship, which implies that the new criteria are less conservative than existing ones. Some examples suggest that the proposed criteria are effective and are an improvement over previous ones.

Oil-Price Forecasting Based on Various Univariate Time-Series Models

Time-series-based forecasting is essential to determine how past events affect future events. This paper compares the performance accuracy of different time-series models for oil prices. Three types of univariate models are discussed: the exponential smoothing (ES), Holt-Winters (HW) and autoregressive intergrade moving average (ARIMA) models. To determine the best model, six different strategies were applied as selection criteria to quantify these models’ prediction accuracies. This comparison should help policy makers and industry marketing strategists select the best forecasting method in oil market. The three models were compared by applying them to the time series of regular oil prices for West Texas Intermediate (WTI) crude. The comparison indicated that the HW model performed better than the ES model for a prediction with a confidence interval of 95%. However, the ARIMA (2, 1, 2) model yielded the best results, leading us to conclude that this sophisticated and robust model outperformed other simple yet flexible models in oil market.

考虑高平峰差异的城市轨道交通节能运行图优化研究

降低能耗是轨道交通绿色低碳、可持续发展的关键。基于“高峰快跑保运力、平峰慢跑降能耗”的思想,本文提出在高平峰时段设置差异化标尺的节能运行图优化方法。首先,根据区间运行时间与列车牵引能耗负相关关系,结合客运服务需求特征,以列车周转牵引能耗最小化为目标构建列车运行标尺优化模型;其次,针对差异化标尺导致的过渡时段列车服务不均匀问题,以列车到站间隔标准差最小化为目标构建列车运行线调整模型;最后,选取福州地铁1号线开展实证分析。结果表明:高平峰差异化标尺节能运行图能够在不改变运力供给、车底运用数量的前提下有效降低全日列车牵引能耗12.56%。所构建方法具有良好的应用价值和可操作性,能够为运营管理人员编制节能运行图提供方法支持。

多维度评价及优化黄芪瞬时高温灭菌工艺

为优化黄芪瞬时高温灭菌(high temperature short time,HTST)工艺参数并多维度考察其对黄芪质量的影响,基于指标相关性的权重系数(criteria importance though intercrieria correlation,CRITIC)法采用正交设计优化黄芪灭菌工艺参数,以灭菌温度、灭菌时间、药材粉碎粒度为考察因素,以灭菌率、5种化合物含量及1,1-二苯基-2-苦基肼自由基(1,1-diphenyl-2-picrylhydrazyl,DPPH·)清除率为考察指标,通过直观及方差分析评价灭菌对3个考察指标的影响;并运用液质联用技术(liquid chromatography-mass spectrometry,LC-MS)确认指纹图谱共有峰的结构,以偏最小二乘回归分析法分析共有峰与抗氧化活性的谱效关系。结果显示,灭菌温度是具有显著影响的因素(P<0.05),最佳灭菌工艺参数为灭菌温度(170±2)℃,灭菌时间5 s,粉碎粒度50目;按优化工艺灭菌后的3批样品微生物水平均符合药典规定,5种化合物含量及DPPH·清除率与灭菌前比较无明显变化;灭菌前后指纹图谱相似度均大于0.900;谱效学分析相关性结果与化合物单体抗氧化的试验结果及其结构特点基本一致。综上所述,瞬时高温灭菌对黄芪中微生物具有明显杀灭作用且对其质量无明显影响,表明该方法适用于黄芪药材灭菌。

A real time processing system of seismic waves using personal computers-Function and characteristics

Seismological Bureau of Sichuan Province, Chengdu 610041, China2) Center for Analysis and Prediction, State Seismological Bureau, Beijing 100036, China3) Observation Center for Prediction of Earthquakes and Volcanic Eruptions, Faculty of Sciences, Tohoku University, Sendai 98077, Japan

论自动投案的时间限制标准认定

符合自动投案的时间限制是自动投案成立的前提和关键,但是目前理论界对于自动投案时间的限制并没有形成一个统一的标准,部分满足法律规定的行为却不符合自动投案的实质,有必要确立一个自动投案时限的实质性标准来填补理论上的空缺。当前,法律规定中的归案标准无法穷尽所有情形,也忽视了抓捕行为对自由意志的影响,致使自动投案的认定存在诸多争议。通过引入控制的概念对归案标准进行明确,以司法机关宣告实施控制作为时限的补充,提出自动投案的时间限制标准。

论医疗纠纷人民调解员管理体制的构建

构建科学的医疗纠纷人民调解员管理体制,建立专业化、职业化的调解员队伍,是保证医疗纠纷调解专业性之前提。应建立调解员资格准入制度,按照统一的调解员选任标准来建立专兼结合、业务能力强、热心于人民调解事业的调解员队伍;设立医疗纠纷调解咨询专家库,保障其运行经费、规定其运行程序、明确专家咨询意见书的作用,以提升医疗纠纷的调解质量;建立调解员考核体系与奖励制度,以推动调解员队伍的专业化和职业化,推进医疗纠纷人民调解事业的持续健康发展。

HCO-ADE求解单点交叉口信号配时问题

为克服信号配时问题求解中单一约束优化方法的局限性,提出混合约束优化自适应差分进化算法(HCO-ADE)。以交叉口通行效率为目标建立信号配时优化模型,依据模型中约束条件被满足程度,采用外罚函数法和可行性准则法相结合的混合约束优化策略(HCOS)对约束条件进行处理,并提出饱和度偏好准则作为自适应差分进化算法(ADE)的选择策略,构建HCO-ADE。最后,以哈尔滨市四相位交叉口高峰时段5 min采集标段交通量数据为例,验证HCO-ADE。结果表明:提出的信号配时问题求解方法可行、有效,优于基于饱和度区间可能度的罚函数约束优化自适应差分进化算法(PFCO-ADE),所得信号配时方案较实测方案平均延误减少3.32%,通行能力提高2.16%,能够更好地提高信号配时方案稳定性。

肾部分切除术后急性肾损伤及其对手术侧肾脏的远期影响

肾部分切除术是治疗局限性小肾癌的首选方法,但手术过程中通常需要暂时阻断肾动脉,不可避免地引发缺血再灌注损伤,严重者甚至发生急性肾损伤。肾部分切除术后急性肾损伤的诊断常采用急性肾损伤网络标准(AKIN)和风险、损伤、失败、损失、终末期肾脏疾病标准(RIFLE),但使用总肌酐升高水平来评估单侧肾损伤显然不够准确;另外,肾部分切除术中会丢失部分正常肾组织,也导致血肌酐升高。为避免上述因素对诊断造成干扰,笔者首先改良了孤立肾肾部分切除术后急性肾损伤诊断分级方法,提出了诊断肾部分切除术后的急性肾损伤需要考虑到正常肾组织丢失引起的血肌酐升高。接着采用“极端值法”量化了非孤立肾患者手术侧肾脏急性肾损伤的程度。最后还探讨了急性肾损伤对手术侧肾脏的远期影响以及减轻肾部分切除术中缺血再灌注肾损伤的潜在方法。

青藏块体东北缘GPS垂向时间序列噪声分析

为了进一步研究青藏块体东北缘全球定位系统(GPS)测站垂向位移序列的最佳噪声模型及对测站垂向速度估计的影响,提出一种青藏块体东北缘GPS垂向时间序列噪声分析方法:选取青藏块体东北缘27个中国内地构造环境监测网络(CMONOC)GPS测站,利用不同的噪声模型对测站垂向位移时间序列进行噪声分析;并探讨赤池信息准则(AIC)、贝叶斯信息准则(BIC)、时间优化贝叶斯信息准则(BICtp)和修正贝叶斯信息准则(BICc)确定的最优噪声模型之间的差异及对测站垂向速度估计的影响。结果表明,AIC确定的最佳噪声模型主要是广义高斯马尔可夫噪声(GGM)+自回归滑动平均噪声(ARMA1)、GGM+白噪声(WN)和WN+闪烁噪声(FN),分别占总测站数的29.6%、22.2%和18.5%,而BIC、BICtp和BICc准则确定的最佳噪声模型主要为WN+FN,分别占总测站数的74.1%、66.7%和70.4%,其次是GGM,分别占测站数的22.2%、22.2%和14.8%;BIC、BICtp、BICc在确定最佳噪声模型过程中,对GGM+ARMA1和GGM+WN噪声模型的影响较大,并且BICc对随机漫步噪声的敏感程度高于BIC、BICtp;不同信息准则确定的青藏块体东北缘垂向速度及不确定度存在一定的差异,但整体垂向趋势基本相同,西南部测站呈现下降趋势,东北边缘测站呈现上升趋势,但上升或下降的幅度相对较小。

有毒气体危害区域划分之临界浓度标准研究

通过研究毒物伤害准则进而界定有毒气体危害浓度,对有毒气体泄漏扩散后的危害区域进行分级划分,以采取相应的防护措施,最大限度的即时有效的减轻有毒气体对人员的伤害。最后,以氯为例,对比其在不同伤害准则下危害区域划分临界浓度标准值,数值差别较大,因此在使用时应根据实际情况加以判断,选择最适当的标准来划分危害区域。

企业新产品研发项目成功标准差异性实证分析——基于时间因素的影响

以时间因素对企业新产品研发(NPD)项目成功标准的影响为研究目标,在国内外相关文献分析的基础之上,提出了五条基于时间因素的企业NPD项目成功标准差异性假设,通过对国内82家企业进行的问卷调查而采集到的数据,使用SPSS软件进行统计学分析,最终验证了五条假设基本成立。