Convolutions and generalization of logconcavity: Implications and applications

Additive convolution of unimodal and α‐unimodal random variables are known as an old classic problem which has attracted the attention of many authors in theory and applied fields. Another type of convolution, called multiplicative convolution, is rather younger. In this article, we first focus on this newer concept and obtain several useful results in which the most important ones is that if is logconcave then so are and for some suitable increasing functions ?. This result contains and as two more important special cases. Furthermore, one table including more applied distributions comparing logconcavity of f(x) and and two comprehensive implications charts are provided. Then, these fundamental results are applied to aging properties, existence of moments and several kinds of ordered random variables. Multiplicative strong unimodality in the discrete case is also introduced and its properties are investigated. In the second part of the article, some refinements are made for additive convolutions. A remaining open problem is completed and a conjecture concerning convolution of discrete α‐unimodal distributions is settled. Then, we shall show that an existing result regarding convolution of symmetric discrete unimodal distributions is not correct and an easy alternative proof is presented. © 2016 Wiley Periodicals, Inc. Naval Research Logistics 63: 109–123, 2016     

一种新的复合导引头多源异步信息融合精确拦截算法

针对单一制导体制难以满足现代战场作战需求，而多传感器数据更新率不同步的问题，建立一种新的微惯导/毫米波/红外复合制导体制，研究了该体制下多传感器异步信息融合的时间同步和空间配准问题；提出一种自适应Unscented卡尔曼滤波算法，该算法采用预测残差构造状态模型误差统计量，通过自适应因子调整状态模型信息对状态参数估值的贡献，有效控制状态模型噪声异常对状态参数估值的影响。将提出的算法应用到微惯导/毫米波/红外复合制导系统中进行仿真验证，结果表明，提出的自适应Unscented卡尔曼滤波算法的解算精度高于标准扩展卡尔曼滤波和Unscented卡尔曼滤波算法，能有效提高导弹的制导的解算精度。     

DEA models for two‐stage processes: Game approach and efficiency decomposition

Data envelopment analysis (DEA) is a method for measuring the efficiency of peer decision making units (DMUs). This tool has been utilized by a number of authors to examine two‐stage processes, where all the outputs from the first stage are the only inputs to the second stage. The current article examines and extends these models using game theory concepts. The resulting models are linear, and imply an efficiency decomposition where the overall efficiency of the two‐stage process is a product of the efficiencies of the two individual stages. When there is only one intermediate measure connecting the two stages, both the noncooperative and centralized models yield the same results as applying the standard DEA model to the two stages separately. As a result, the efficiency decomposition is unique. While the noncooperative approach yields a unique efficiency decomposition under multiple intermediate measures, the centralized approach is likely to yield multiple decompositions. Models are developed to test whether the efficiency decomposition arising from the centralized approach is unique. The relations among the noncooperative, centralized, and standard DEA approaches are investigated. Two real world data sets and a randomly generated data set are used to demonstrate the models and verify our findings. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008     

带裂缝钢筋混凝土梁振动特性变刚度模型分析

按常规等刚度、匀质线性材料来考虑开裂后的钢筋混凝土梁，必然带来较大的误差，与实际情况存在较大差距。基于条带法提出了建立带裂缝钢筋混凝土梁的变刚度模型分析方法，对考虑开裂和材料非线性的钢筋混凝土简支梁的振动特性进行了理论计算和试验研究。结果表明：提出的方法从理论上可以得到既有钢筋混凝土简支梁的振动特性、裂缝开展情况等参数，理论计算结果与试验结果吻合较好，且精度较高，具有良好的可行性和工程适用性。     

电驱动车辆反馈线性化自适应滑模滑移率控制

针对驱动和制动工况下电驱动汽车的滑移率控制这一强非线性和不确定性控制问题,提出了一种基于反馈线性化的自适应滑模控制(ASMC)方法。针对车辆驱动、制动工况下的车轮滑移率进行了动力学分析,建立了统一的状态方程。充分利用系统已知模型和参数,采用线性化反馈消除非线性变化的控制量增益系数的影响,通过对反馈项增益参数的自适应调整,适应附着路面不确定参数变化的控制要求,克服系统控制中存在的主要非线性和不确定性部分,对于系统难以建模描述部分,视为扰动,利用滑模控制抑制系统该部分的不确定性因素,同时保证系统响应的快速性,并对算法进行了Lyapunov稳定性分析。最后,以某型电动汽车为对象进行了仿真分析,结果表明采用ASMC控制系统动态响应快、精度高、抗扰能力强,对路面参数变化具有较强的鲁棒性,同时输出控制量抖振小。     

基于规则的动态频谱接入研究

动态频谱接入面临的关键技术之一是对接入时机和方式进行有效地管控,防止由于频谱的接入使用过于灵活造成用频的干扰和混乱。将频谱接入的时间和方式给予规则上的约束和指导,基于规则构建动态频谱管理框架可以有效实现频谱的实时管控。对动态频谱接入的规则及表述方式进行了讨论,分析了基于规则的动态频谱接入过程,最后结合美军XG项目的试验结果分析了基于规则的动态频谱接入的应用前景。     

TETRA数字集群宽带化演进

TETRA数字集群空中接口所涉及的调制方式、传输速率、信道编解码和高层协议等方面的标准化工作是在支持原有话音业务的基础上,以支持分组数据和多媒体业务为新的服务目标,为满足宽带化通信需求进行的改进和完善。     

邻域灰度差加权的模糊C均值聚类图像分割算法

模糊C均值(FCM)算法用于灰度图像分割是一种非监督模糊聚类后再标定的过程,适合灰度图像中存在着模糊和不确定性的特点.但是这种算法没有考虑到样本空间中不同的样本点对分类的贡献不同,因此分割效果不理想.提出了邻域灰度差加权的模糊C均值聚类算法,实验结果表明,该算法不仅取得了很好的分割效果,而且加快了算法的收敛速度,从而满足了图像分割的有效性、实时性的要求.     

基于Web Service网络管理体系结构研究

传统层次型网络管理体系结构中网络管理系统之间交互困难。基于Web Service体系结构的思想,将网络管理系统提供的管理功能抽象成管理服务,提出了具有面向服务、动态协作等特点的基于Web Service的网络管理体系结构,并详细讨论了该体系结构涉及的网络管理资源和服务的描述方法以及服务组合技术。     

基于粒子群优化的稀疏序列Bayes反卷积方法研究

在地下目标低频声波探测中,由于探测信号的混叠,难以判读反射目标的空间位置.应用信号处理方法求解时,目标信号是稀疏序列,求解方程是病态的.运用Bayes反卷积方法修正其病态性,并采用优化的粒子群算法求解,提高了系统的探测分辨率,同时降低了计算量.实际应用表明,该方法是有效的.