一种快速稀疏贝叶斯学习的水声目标方位估计方法研究

针对以具有时序结构的稀疏贝叶斯学习(Temporally multiple sparse Bayesian learning,TMSBL)为重构算法的水声目标DOA (Direction-of-arrival)估计方法存在运算速度慢的问题,结合块稀疏贝叶斯学习(Block-spare Bayesian learning,BSBL)理论框架下DOA估计模型与特点,采用MacKay提出的定点方法(Fixed-point method)对TMSBL算法中的核心超参量进行求解,提出一种快速的水声目标方位估计稀疏贝叶斯学习的方法,该方法具有运算速度快,重构概率高的特点,并通过实验仿真从运算时间、失败率和均方根误差等方面与TMSBL算法进行比较,验证了该方法的可行性与有效性。      

Blow-up rate estimate for degenerate parabolic equation with nonlinear gradient term

Abstract In this paper, the blow-up rate is obtained for a porous medium equation with a nonlinear gradient term and a nonlinear boundary flux. By using a scaling method and regularity estimates of parabolic equations, the blow-up rate determined by the interaction between the diffusion and the boundary flux is obtained. Compared with previous results, the gradient term, whose exponent does not exceed two, does not affect the blow-up rate of the solutions.     

On the calculation of energy release rate for viscoelastic cracked laminates

IntroductionGenerallyspeaking ,acrackinviscoelasticmaterialswillgrowinsomeunknownspeedeveniftheappliedloadisquasistatic,thusthemaindifficultyisinducedindervingtheenergyreleaserate .Knowledgeoftheconditiongoverningthedelaminationincompositelaminateswithviscoelasticlayersisofparamountimportanceinpracticalapplications.Forexample,inplasticencapsulatedICpackages,theinterfacialdelaminationbetweentheSilicondieandviscoelasticepoxymoldingcompoundunderthethermalloadingisthemainfailuremodeofthestructure…     

Analytical solutions of thermal stress distribution in plastic encapsulated integrated circuit packages

IntroductionElectronicpackagesarecomplexcompositestructure.Theyhavemyriadcornersandinterfacesthatcanactaspotentialfailuresitesduringfieldoperation .Atpresenttime ,plasticencapsulatedintegratedcircuits (ICs)arewidelyusedinengineering .AplasticencapsulatedICpackageconsistsofasilicondie,dieattachment,passivation ,wireinterconnects,aleadframe ,andplasticmoldingcompound .Thermalexcursionduringpackagequalificationfromthermalcycling thermalshock ,orpowercyclingduringnormaloperationcansetupthermomec…     

基于内变量理论的电流变液本构关系

研究了电流变液的微结构本构关系.其理论框架是基于内变量理论和机理的分析.电流变液是由高介电常数的颗粒悬浮在某种液体中组成的.在电场作用下,极化的颗粒将沿着电场方向聚集在一起形成链状结构.颗粒聚集体的大小和方向将随外加电场和应变率的变化进行调整,因而可以通过建立起能量守恒方程和力平衡方程来确定颗粒聚集体的大小和方向的变化.那么,一个三维的、清晰的本构关系可以由相互作用能和系统的耗散能导出.具体考虑和讨论了在简单剪切载荷作用下的系统响应,发现电流变液的切变剪薄粘滞系数同系统Mason数之间近似于幂指数∝(Mn)-082的关系.     

压电材料中两平行对称可导通裂纹断裂性能分析

采用Schmidt研究了压电材料中对称平行的双可导通裂纹的断裂性能,利用富里叶变换使问题的求解转换为求解两对以裂纹面位移之差为未知变量的对偶积分方程,并采用Schmidt方法来对这两对对偶积分程进行数值求解。结果表明应力强度因子和电位移强度因子与裂纹的几何尺寸有关。与不可导通裂纹有关结果相比,可导通裂纹的电位移强度因子远小于相应问题不可导通裂纹的电位移强度因子。     

Investigation of a griffith crack subject to uniform tension using the non-local theory by a new method

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