Optimal reduced-order interval observer design for uncertain continuous-time linear systems

This article investigates the reduced-order interval observer (R-IO) design technique for continuous-time linear systems with unknown external disturbances and measurement noises. First, we propose a coupled R-IO structure with more design degrees of freedom, and it can be directly applied not only to solve the difficulty of the error system cooperativity construction but to relax the constraint on the sensor measurement noises. Second, the R-IO existence condition is derived as a set of matrix equations (MEs), and a complete solution, explicitly showing the available design parameters, to such an R-IO is further obtained by solving the MEs. Third, using the solution, an integrated optimization indicator of the R-IO performance is built as the valid selection mechanism of these parameters. Finally, the efficiency of the obtained results is illustrated through a numerical example and a practical example.     

基于混合多维云模型的工业绿色发展水平测度

如何测度各省工业绿色发展水平高低, 判断各省工业绿色创新能力差异, 本文从绿色投入要素和绿色产出效益视角构建集结综合属性值的工业绿色发展多指标评价体系; 并在云模型基础上提出了基于混合多维云模型的区间多属性测度方法. 该方法创新性地利用区间权重和云权重的相互转换, 在解决多指标权重不一的问题后, 再运用父云贴近度计算工业绿色发展水平, 云投影度测定工业绿色创新能力; 最后采用省际间的工业面板数据进行验证. 结果表明, 相较于一般的多指标综合评价法, 该测定方法的实证结果与实际情况更相符合, 说明了该方法既能对工业绿色发展水平的整体情况进行评价分析, 也能精确计算出各指标贡献度, 从而判断其是否具有工业绿色创新能力. 因此, 本研究可为各地区调整工业绿色发展水平测度指标、制定工业绿色发展规划提供实质性建议和理论决策依据.     

机械结构相似度评价及可靠性预计研究

在用传统的相似产品法进行可靠性预计时,所选取的相似产品与评价对象之间差异较大,会造成预计结果的偏差较大。为解决这一问题,提出了一种基于"功能—运动—动作"结构化分解的可靠性预计新方法。通过明确产品的各大运动功能建立功能层,分析完成各功能的机械部件运动建立运动层,确定实现各机械部件运动的元动作运动单元建立元动作层,建立了可靠性预计的"功能—运动—元动作运动单元"层次模型。引入区间层次分析法,确定了"功能—运动—元动作运动单元"层次模型中各子代运动单元对父代运动单元的可靠性影响权重,并构建了由子代运动单元预计父代运动单元可靠性的数学模型。确定影响评价机械结构相似度的因素,构建了区间数综合评判云模型并选取与元动作运动单元相似的参考结构,以区间数综合评价云模型得出的相似度值修正参考结构的可靠性数据来预计元动作运动单元的可靠性。将元动作运动单元的可靠性预计值代入数学模型,层层预计父代运动单元的可靠性,从而得出整个产品的可靠性水平。最后以数控转台为例进行了分析,得出了可靠性预计值,并将该方法与传统方法进行了比较。结果表明,新的可靠性预计方法具有较好的可行性和较高的准确性。     

Fitting fatigue data with a bi‐conditional model

The formulation of a probability‐stress‐life (P‐S‐N) curve is a necessary step beyond the basic S‐N relation when dealing with reliability. This paper presents a model, relevant to materials that exhibits a fatigue limit, which considers the number of cycles to failure and the occurrence of the failure itself as statistically independent events, described with different distributions and/or different degree of scatter. Combining these two as a parallel system leads to the proposed model. In the case where the S‐N relation is a Basquin's law, the formulations of the probability density function, cumulative distribution function, quantiles, parameter and quantile confidence interval are presented in a procedure that allows practically any testing strategy. The result is a flexible model combined with the tools that deliver a wide range of information needed in the design phase. Finally, an extension to include static strength and applicability to fatigue crack growth and defects‐based fatigue approach are presented.     

An efficient hybrid reliability analysis method with random and interval variables

Random and interval variables often coexist. Interval variables make reliability analysis much more computationally intensive. This work develops a new hybrid reliability analysis method so that the probability analysis (PA) loop and interval analysis (IA) loop are decomposed into two separate loops. An efficient PA algorithm is employed, and a new efficient IA method is developed. The new IA method consists of two stages. The first stage is for monotonic limit-state functions. If the limit-state function is not monotonic, the second stage is triggered. In the second stage, the limit-state function is sequentially approximated with a second order form, and the gradient projection method is applied to solve the extreme responses of the limit-state function with respect to the interval variables. The efficiency and accuracy of the proposed method are demonstrated by three examples.     

多目标群体决策的区间层次分析法研究

基于专家个体判断矩阵,应用数理统计及误差理论,探讨了综合判断矩阵的建立途径,给出了用区间层次分析法求解多目标群体决策问题的算法与步骤,最后以算例说明该方法的实用性及有效性。     

车载无线电台同址干扰测试与分析

同址干扰是车载、舰载、机载无线电通信中面临的一个重要问题,针对同址干扰对复杂通信系统的影响提出了一种有效的测试和分析方法;首先对车载电台的各种天线进行了耦合度测试,从实验和仿真两方面阐述了同址干扰的严重程度,为进一步定量分析同址干扰的影响,构建了有线测试平台;在需求分析基础上,详细介绍了平台的组成,并以短波、超短波电台为对象,通过大量现场实验,深入分析了误码率,同址工作电台的频率间隔和功率之间的相互关系;研究表明,同址干扰的定量分析是设计车载通信系统,合理分配电台工作参数的关键环节。     

高脉冲重复频率雷达混合滤波解距离模糊方法

针对高脉冲重复雷达距离模糊问题,提出一种新的混合滤波解距离模糊方法.通过把脉冲间隔数和脉冲间隔变化量作为目标待估计状态,对离散的脉冲间隔数、间隔变化量和连续的目标状态(位置和速度)进行混合滤波,从而将解距离模糊问题转换为对脉冲间隔数的估计问题.初始时刻,由于距离量测模糊,利用多个高脉冲重复频率(HPRF)采用欧氏距离对混合状态进行初始化.在滤波过程中,为了避免门限选择,首先根据脉冲间隔变化量的有限个离散取值,将六维向量的混合滤波模型等效为有限个五维向量的混合滤波模型;然后对量测分别进行混合滤波;最后通过对各模型得到的新息的2范数进行比较获得混合状态估计,从而实现解距离模糊.混合滤波解距离模糊方法为实现高脉冲重复频率雷达实时解距离模糊提供了一种新的研究思路,仿真结果表明,本文提出的混合滤波方法在只有一个脉冲重复频率获得目标量测时较现有多假设方法收敛速度快,并且可以克服多假设方法在脉冲间隔数变化时发生的解模糊错误.     

区间序信息系统及其属性约简算法

在不含决策属性的区间序信息系统中,区间偏序关系的不完备性造成信息流失。针对该问题,提出一种新的基于区间模糊数的区间序全序关系,以此建立区间序信息系统,并分析其相关上、下近似的单调性和包含性。采用不可区分函数的方法,给出区间序信息系统的属性约简算法,并通过算例验证了该算法的有效性。     

基于最大隶属度的区间概率灰色随机多准则决策方法

定义了一种灰色隶属函数.针对概率为区间数、准则值为区间灰数的灰色随机多准则决策问题,提出一种基于最大隶属度的决策方法.首先,运用区间数可能度排序向量将区间概率转化为点概率,并将其转化为无风险决策问题;然后,计算各方案在负理想方案到正理想方案上的灰色隶属度,并计算各方案准则值的相对灰度,进而根据灰色隶属度和相对灰度大小对方案进行排序;最后,通过算例验证了该方法的可行性和有效性.