Effect of AlN content on the performance of brominated epoxy resin for printed circuit board substrate

Polymer matrix composites, based on brominated epoxy, a type of material widely used in printed circuit boards (PCBs), as matrix and AlN particle as filler were prepared. The influences of AlN content on the mechanical, thermal, and electrical properties of the composites were investigated by uniaxial tensile test, TMA, thermal conductivity measurement, DMA, and dielectric properties measurement. It was found that the properties of composites monotonically varied with AlN content except that maximum tensile strength and strain of composites corresponded to a filler content of 10 wt %. The results of DMA also showed the AlN reinforcement was more pronounced above T_g, and the peak area of tan δ versus T curves decreased with AlN content, which implied the damping capacity of the composite gradually decreased. The increase in T_g and decrease in damping were probably due to strong interaction between the AlN and epoxy matrix inhibiting the mobility of the epoxy chain. In addition, different theoretical models reported in the literature were used to predict the E, CTE, k, and D_k, and compared with the experimental data. Finally, suitable models were recommended in the present materials system. For the significant improvement of performance of epoxy, we can conclude that these composite materials may be promising for PCB substrate. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1662–1674, 2007     

Diffusion approximation for billiards with totally accommodating scatterers

We study the 2D motion of independent point particles colliding with a periodic array of circular obstacles. The interaction between the particles and the obstacles is described by a total accommodation reflection law. Assuming that the array of scatterers has finite horizon, the density of particles is approximated by the solution of a diffusion equation in the long-time and large-scale regime. The proof relies on a multiscale asymptotics and gives the order of approximation.     

小康判别函数的建立与分析

近几年，国内在研究小康水平的定量指标分析中，应用较多的有综合评分法、层次分析法和模糊识别法。这几种方法比单项指标更全面、灵活，但在权数的确定上都难以克服人为因素的影响。当指标之间存在两个或两个以上的高度相关时，对问题的研究总存在一定的局限性。为了科学地研究小康问题，本文基于判别分析，建立城市小康的判别系数，来综合评价出我国城市小康水平的定量标准。     

A Note on Single Machine Scheduling with Coefficient of Completion Time Variation Minimization

1.IntroductionGivenasetN~{1,2,...,n},n>1,ofindependentandsimultaneouslyavailablejobswhicharetobeprocessednonpreemptivelyonasinglemachine,jobirequiresapositiveprocessingtimepiandisassignedapositiveweightfi,iEN.Let11bethesetofn!possiblepermutationsofintegers1,2,...,n,and7~{[l],[2]!...I[n]}E11beajobsequencewhichdenotesthatjob[k]isthekthjobtobeprocessedonthemachine.Assumethatthemachinestratstoprocessthefirstjobattimezero.TheproblemistofindajobsequenceT*E11tominimizewhereC[i]isthecompletiontime…     

球面反射镜的放大自发辐射方法测量小信号增益的理论研究

提出了球面反射镜的放大自发辐射（ＡＳＥ）方法测量小信号增益的理论模型，给出了相应的小信号增益系数的计算公式，该公式具有精确，简洁，显函数等特点，该模型有抑制光束横向分布引起的测量误差的机制。     

一种模拟非线性复杂系统的简化方法——疏系数化方法

用非线性时间序列模型描述复杂系统，往往因模型参数过多而导致负效应，疏系数化方法能简化模型结构、实现系统内在规律，甚至可以提高摸拟精度     

Maluta's coefficient in Musielak-Orlicz sequence spaces equipped with the Orlicz norm

Maluta's coefficient of Musielak-Orlicz sequence spaces equipped with the Orlicz norm is calculated. A sufficient condition for the Schur property of these spaces is given.

     

PTC热敏电阻器的电阻温度特性及应用

本文从半导体陶瓷PTC热敏电阻器入手，讨论了该热敏材料的电阻温度特性，给出了PTC热敏电阻器的测量结果和应用范围。     

渐变折射率光波导的精确分析

本文利用转移矩阵理论和等效衰减系数的概念，导出了渐变折射率光波导的色散方程，数值计算的结果，赢余方程的精度优于目前存在的所有近似方法。     

Phase transitions and reflection positivity for a class of quantum lattice systems

We prove a form of reflection positivity in planes containing sites for a class of quantum lattice systems. As an application, a proof is given of a phase transition for the Fisher-stabilized Ising antiferromagnet in an external magnetic field with parallel and transverse components, both by the method of infrared bounds and by a suitable version of the Peierls argument. We also discuss the spherical model in an appendix.