Transfer matrix approach of vibration isolation analysis of periodic composite structure

The transmission properties of elastic waves propagating in a three-dimensional composite structure embedded periodically with spherical inclusions are analyzed by the transfer matrix method in this paper. Firstly, the periodic composite structures are divided into many layers, the transfer matrix of monolayer structure is deduced by the wave equations, and the transfer matrix of the entire structure is obtained in the case of boundary conditions of displacement and stress continuity between layers. Then, the effective impedance of the structure is analyzed to calculate its reflectivity and transmissivity of vibration isolation. Finally, numerical simulation is carried out; the experiment results validate the accuracy and feasibility of the method adopted in the paper and some useful conclusions are obtained. Project (No. 50075029) supported by the National Natural Science Foundation of China.     

Electrochemical Immunoanalysis for Carcinoembryonic Antigen Based on Multilayer Architectures of Gold Nanoparticles and Polycation Biomimetic Interface on Glassy Carbon Electrode

This paper describes a layer‐by‐layer (LBL) self‐assembly process of chitosan (CTS) and gold nanoparticles (Au) on the pretreated negatively charged glassy carbon (GC) electrode to fabricate electrochemistry immunosensor with a nontoxic biomimetic interface, which provided an environment similar to a native system and allowed more freedom in orientation for immobilization of carcinoembryonic antibody (anti‐CEA) to monitor carcinoembryonic antigen (CEA). UV‐vis spectroscope, atomic force microscopy (AFM), and cyclic voltammetric (CV) measurements were used to follow the multilayer film formation. The performance of the biominetic interface and factors influencing the assay system were investigated in detail. The differential pulse voltammetry (DPV) current response is used for the CEA concentration assay. The dynamic range was from 0.50 to 80.00 ng mL^?1 with a detection limit of 0.27 ng mL^?1 at 3σ. In addition, the experiment results indicate that immobilization described in this proposed method exhibits a good sensitivity, selectivity, and stability.     

HART协议物理层设备的测试(上)

本文介绍HART协议物理层设备的测试要求、测试设备、测试方法及测试时的一些特别说明。     

智能化多业务网络

首先从不同角度分析了通信服务商目前面临的环境,包括通信服务业的投资趋势、业务发展趋势、服务提供商的业务收入情况以及用户的需求;接着介绍了朗讯的智能化多业务网络的整体架构和解决方案;其中重点描述了智能化多业务网络在网络传输层、业务控制层和应用层上的智能化以及包括核心网络、城域网络在内的六大解决方案。     

只读式超分辨光盘的膜层设计和分析

超分辨技术是一种无需减小记录波长或增大数值孔径而提高存储密度的方法。Ge Sb Te是一种良好的相变光存储材料 ,在超分辨光盘中可作为掩膜。利用多层膜反射率的矩阵法计算了掩膜为Ge2 Sb2 Te5薄膜的超分辨只读式光盘的光学参数与各膜层厚度之间的关系 ,最后得到了较为理想的膜层厚度匹配。采用磁控溅射法制备了只读式超分辨光盘 ,测量了光盘的光学性质。     

金属PTC陶瓷复合材料结构及其导电机理

研究了金属ＰＴＣ陶瓷复合材料的电学性能和其材料组分。结果表明，掺入金属的ＰＴＣ陶瓷材料经氮气中烧结，然后在空气中进行热处理，材料表面形成高势垒层，金属ＰＴＣ陶瓷复合材料的室温电阻较ＰＴＣ的陶瓷高。样品之中存在大量不同类型的极化，在低温时样品电阻较高，温度增加后，大量各种类型离子极化出现，在变价金属铁的变价导电作用下，削弱表面势垒，使金属ＰＴＣ陶瓷复合材料电阻降低，表现出ＮＴＣ现象。在电场作用下，正负电荷、晶粒畸变和空位缺陷等产生空间电荷极化使金属ＰＴＣ陶瓷复合材料有较高介电常数。介电损耗（ｔｇδ）频谱和介电δ温度谱上都出现一个介电峰，其主要原因是跃迁极化，金属阳离子由一个位置跃迁到另一个位置，在介电损耗所对应的频率和温度时出现跃迁极化率最大     

Experience Gained Using Second-Moment Closure Modeling for Transitional Flows Due to Boundary Layer Separation

This paper presents detailed information on the experience gained during the attempts to model a set of transitional flows due to boundary layer separation. These flows are developed on a flat plate with a semi-circular leading edge and they have been coded by the ERCOFTAC Special Interest Group on Transition, as T3L flows. Different freestream velocities and turbulence intensities configure these transitional flows and, by consequence, govern the transition mechanism, resulting in larger or smaller transitional regions. The modeling of the T3L flows has been performed by adopting a low-Reynolds number second-moment closure turbulence model. The results showed satisfactory agreement with the experimental measurements, although some difficulties regarding successful convergence have been faced. The final conclusion is that turbulence modeling can present quite accurate results for transitional flows without any additional use of ad-hoc modifications or additional equations based on various transition models and intermittency transport modeling.     

脉冲激光LGA法钛表面氮化及其XRD和SEM微观分析

用调Ｑ－ＹＡＧ和ＸｅＣｌ脉冲激光在钛表面以激光气体合金化方法生成氮化钛层，用Ｘ射线衍射仪分析了不同激光能量、不同Ｎ２气压不同作用脉冲数等条件下ＴｉＮ的结晶取向、结晶形态、氮化程度，用扫描电镜观察了它们的微观结构，对脉冲激光的ＬＧＡ法机理进行了探讨，也发现了用ＬＧＡ法对Ｍｏ的氮化生成Ｍｏ２Ｎ．     

高层印制线路板正面临的对位挑战

封装工业正在推动着印制线路板技术水平朝着半导体要求的方向发展。高密度印制线路板正广泛用于网络路由器、自动测试设备和服务器领域。高密度要求(>150 IO/cm~2)正成为客户的普通需求。为满足现有的高密度封装要求,由于线宽、线距和通孔孔径正接近传统制作极限,普遍的方法就是不断增加印制线路板的层数。这些特征正驱动着印制线路板在基材、图像转移、蚀刻、电镀、阻焊、测试流程和对位系统的变化。此文主要讲述了印制线路板特性的变化趋势和利用对位模式和雷利分布去预测满足高级对位要求的能力以及印制线路板各流程中有关对准度的控制要点。     

非线性编辑中特效图文素材的应用

Cool 3D是一款特效图文制作软件，适用于动画片段、3D文字、图形等制作场合。Cool 3D中制作的特效素材应用于非线性编辑中，可以丰富素材的表现形式，提高节目编辑制作的整体质量。