Monitoring censored lifetime data with a weighted‐likelihood scheme

Lifetime experiments are common in many research areas and industrial applications. Recently, process monitoring for lifetime observations has received increasing attention. However, some existing methods are inadequate as neither their in control (IC) nor out of control (OC) performance is satisfactory. In addition, the challenges associated with designing robust and flexible control schemes have yet to be fully addressed. To overcome these limitations, this article utilizes a newly developed weighted likelihood ratio test, and proposes a novel monitoring strategy that automatically combines the likelihood of past samples with the exponential weighted sum average scheme. The proposed Censored Observation‐based Weighted‐Likelihood (COWL) control chart gives desirable IC and OC performances and is robust under various scenarios. In addition, a self‐starting control chart is introduced to cope with the problem of insufficient reference samples. Our simulation shows a stronger power in detecting changes in the censored lifetime data using our scheme than using other alternatives. A real industrial example based on the breaking strength of carbon fiber also demonstrates the effectiveness of the proposed method. © 2016 Wiley Periodicals, Inc. Naval Research Logistics 63: 631–646, 2017     

激光焦点控制磁力驱动的控制特性实验对比分析

为了满足激光焦点控制系统的位置和速度响应要求,设计了一种轴向放置、轴向磁化的环形永磁体自复位的3自由度激光焦点磁力驱动微动平台。根据该微动平台的结构进行力学分析并建立动力学方程,在此基础上进行微动平台的比例、积分、微分控制实验和鲁棒控制实验。通过两种不同控制策略的对比分析,结果表明,两种控制策略都能实现微动平台的稳定驱动,但是在比例、积分、微分控制策略下,响应速度更好,在鲁棒控制策略下,抗干扰能力更好。     

浅谈我国宪法监督制度的完善

宪法是我国的根本大法,对国家政治、经济、社会生活有着重要权威性。宪法监督是依宪治国的关键。我国现有宪法监督制度有着明显的缺陷,中国应当既立足本国实际,又顺应世界宪政发展的基本潮流,完善宪法监督制度,充分发挥宪法作为根本大法的作用。在分析了我国宪法监督体制弊端的基础之上,对我国宪法监督体制的完善提出了一些建议。     

共享态势认识的效用

态势认识是指挥控制过程在认知域中的重要环节,认识共享是改进态势认识、减少认识偏差的重要手段。文中在分析态势认识的基础上,提出战术相关要素的发现概率、态势认识中的理解程度和理解偏差的概念,建立了用于态势认识的定量评估的数学模型,分析了认识共享对战场态势认识的改进程度,导出了团队合作时战术相关要素发现概率与个体数量的关系式,给出理解偏差与个体数量的联系方程并求出极值条件。     

基于PIC16F877及RTL8019AS构成的PIC网络组件及应用

介绍了基于PIC16F877及RTL8019AS构成的PIC网络组件.使用该组件,可以通过PC或其它设备(如手机等)经网络对某些电器实行远程控制及监测.     

基础阻抗对隔振效果的影响

经典隔振理论评价隔振效果常假定基础为绝对刚性,这在隔振效果评价和测量上带来了很大的问题,导致计算结果偏差很大.针对这一问题推导了柔性基础上的传递率计算公式,讨论了基础阻抗对隔振效果的影响.理论分析表明,柔性基础的基频和质量是影响隔振效果的最重要因素.     

非线性系统参数识别的傅里叶级数展开法

采用电液伺服材料试验机加载方式,通过位移控制和傅里叶级数展开技巧,将含有滞迟环节系统的非线性参数识别问题转化为扩充参数的线性识别问题,为钢丝绳、金属橡胶构成的隔振系统的模型识别奠定了重要的理论基础。     

机电伺服系统的预测函数控制算法研究

针对典型机电伺服系统,提出了一种PFC PID串级透明控制策略,通过内环PID控制来提高抗干扰性,调节PID参数将其拟合成为一阶加纯滞后系统,作为外环PFC控制的广义对象,外环采用预测函数控制来获得良好的跟踪性能和强鲁棒性。详细分析了预测函数控制在具有参数饱和限制环节和滞后的机电伺服系统中的实施算法,分析了系统的闭环性能,并得到了其稳定鲁棒性条件。通过仿真验证了方法具有良好的鲁棒性和抗干扰能力。     

A sequential dynamic pricing model and its applications

Consider a sequential dynamic pricing model where a seller sells a given stock to a random number of customers. Arriving one at a time, each customer will purchase one item if the product price is lower than her personal reservation price. The seller's objective is to post a potentially different price for each customer in order to maximize the expected total revenue. We formulate the seller's problem as a stochastic dynamic programming model, and develop an algorithm to compute the optimal policy. We then apply the results from this sequential dynamic pricing model to the case where customers arrive according to a continuous‐time point process. In particular, we derive tight bounds for the optimal expected revenue, and develop an asymptotically optimal heuristic policy. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2004.     

微型飞行器飞行控制问题研究进展

微型飞行器(MAV)是飞行器的一个新兴发展方向,其飞行控制问题是MAV研究中最具挑战性的关键技术问题。对MAV飞行控制系统的结构及其特点进行了归纳和评述,分析了国内外MAV飞行控制系统的研究现状,对其中的一些关键技术问题进行了讨论,包括飞行控制方案、机载传感器、控制算法以及控制器设计方法等内容。