弹性基上圆柱管弯曲行为的高阶剪切梁理论解

以弹性基上圆柱管为研究对象,基于高阶剪切变形梁理论推导了Winkler弹性基圆柱管弯曲变形的高阶剪切梁理论控制方程,给出四种典型工况弯曲问题的精确解.研究表明,无须假设剪切修正系数,只需引入适当横截面翘曲形状函数,高阶梁理论在圆柱管内外表面满足剪应力τxr为零的边界条件,且对于不同长径比和厚径比的圆柱管弯曲问题均能提供...     

无奇点三维攻击时间控制滑模导引律

为研究导弹在视场角约束下的三维攻击时间控制问题,提出一种三维非线性滑模导引律。利用攻击时间误差设计滑模面,推导出三维形式的俯仰和偏航加速度指令;通过对所设计制导律进行简单修正,解决了零初始前置角引起的奇点问题;从数学上证明了该导引律的稳定性和收敛性,讨论了导引律相关参数的取值范围,分析了与纯比例导引法、解耦三维导引律之间的关系。仿真结果表明,所设计导引律能够在视场角约束条件下有效实现攻击时间增大或减小的控制;俯仰和偏航平面的耦合程度越强,该导引律控制能耗小的优势越为明显。     

A Fuzzy Cluster and Retinex Theory-based Variation Model for Inhomogenous Image Segmentation

A variational inhomogeneous image segmentation model based on fuzzy membership functions and Retinex theory is proposed by introducing the fuzzy membership function.The existence of the solution of the proposed model is proved theoretically.A valid algorithm is designed to make numerical solution of the model under the framework of alternating minimization.The last experimental results show that the model can make segmentation of the real image with intensity inhomogeneity effectively.     

Buckling analysis of embedded graphene oxide powder-reinforced nanocomposite shells

In this study, the buckling analysis of a Graphene oxide powder reinforced (GOPR) nanocomposite shell is investigated. The effective material properties of the nanocomposite are estimated through Halpin-Tsai micromechanical scheme. Three distribution types of GOPs are considered, namely uniform, X and O. Also, a first-order shear deformation shell theory is incorporated with the principle of virtual work to derive the governing differential equations of the problem. The governing equations are solved via Galerkin's method, which is a powerful analytical method for static and dynamic problems. Comparison study is performed to verify the present formulation with those of previous data. New results for the buckling load of GOPR nanocomposite shells are presented regarding for different values of circumfer-ential wave number. Besides, the influences of weight fraction of nanofillers, length and radius to thickness ratios and elastic foundation on the critical buckling loads of GOP-reinforced nanocomposite shells are explored.     

Size dependent free vibration analysis of functionally graded piezoelectric micro/nano shell based on modified couple stress theory with considering thickness stretching effect

Higher-order shear and normal deformation theory is used in this paper to account thickness stretching effect for free vibration analysis of the cylindrical micro/nano shell subjected to an applied voltage and uniform temperature rising. Size dependency is included in governing equations based on the modified couple stress theory. Hamilton's principle is used to derive governing equations of the cylindrical micro/nano shell. Solution procedure is developed using Navier technique for simply-supported boundary conditions. The numerical results are presented to investigate the effect of significant parameters such as some dimensionless geometric parameters, material properties, applied voltages and temperature rising on the free vibration responses.     

现代军事情报处理方法中的语言、语音技术

军事情报的收集、处理和分析是情报部门的重要工作,当今时代,依靠人工搜集处理方法在效率上已经不能满足需要,采用先进的信息处理技术对情报进行自动处理技术正是解决这一问题的有效途径。大部分的情报载体是文字和语音．因此自然语言和语音处理技术在情报处理方面发挥着重要作用。针对军事情报处理方法中的语言、语音处理技术进行简单的介绍,包括机器翻译、信息检索,语音分析、语音识别等方面。     

排队论在导弹防御体系射击效能中的应用

针对当前空袭手段多样化、综合化和一体化的特点,运用排队论方法,设计了一种基于排队论的射击效能评估模型。该模型综合考虑了各种因素对舰空导弹射击效能的影响,当编队的配置(如防御层数、通道数量)有所变化时,依然可以灵活运用上述模型对编队射击效能做出准确评估。     

现代机载探测系统多源信息融合算法

针对机载探测系统的特性,应用Dempster-Shafer(D-S)证据理论和主观Bayes的组合算法,对来自机载SAR雷达、机载前视红外搜索跟踪系统(IRS)、电子支援系统(ESM)等探测系统多次观测所获得的数据,以及来自地面的电子情报(ELINT)的不同信息进行实时融合、识别,进而确定攻击对象.通过实例进行仿真证明,这种组合算法适用于不同类传感器和不同格式信息间的融合,适合于复杂信号环境.     

新型驱护舰编队舰空导弹防御体系射击效能研究

针对新型驱护舰编队舰空导弹防御体系射击效能评估这一难题,对其射击效能准则进行了确立,提出了基于排队论的射击效能评估模型,对体系射击效能进行仿真计算,总结出能对系统射击效能做出准确评估的方法,并利用实例对模型进行了验证。     

Relaxed sequencing games have a nonempty core

We study sequencing situations with a fixed initial order and linear cost functions. Cost savings can be obtained by rearranging jobs. Next to finding an optimal order, an additional issue is formed by the division of these savings. Cooperative game theory studies this issue. A common assumption states that cooperation between players is restricted to groups that are connected according to the initial order. The value of disconnected groups is defined additively over their connected components. In this paper we allow players in disconnected coalitions to switch places as long as they do not hurt the players not in the coalition under consideration. The resulting games are called relaxed sequencing games. Although they have been studied before, no general results on stable profit divisions have been derived so far. In this paper we prove that relaxed sequencing games have a nonempty core, i.e., they all have stable profit divisions. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006