PCB翘曲度控制

本文从PCB的设计、物料选择、压板程序、流程操作等四个方面介绍了影响PCB弯曲度的一些因素。     

First-principles calculations of the effect of Ge content on the electronic,mechanical and acoustic properties of Li17Si4-xGex

The electronic, mechanical and acoustic properties of Li₁₇Si_4-xGe_x (x = 0, 2.3, 3.08, 3.53, and 4) have been investigated by using first-principles calculations based on the density functional theory (DFT). The research shows that the bulk modulus B, Young's modulus E, shear modulus G, and hardness H_v gradually decrease with the increasing Ge content. Li₁₇Si_4-xGe_x have the brittle nature from the analysis of B/G ratio and Cauchy pressure. The maximum Young's moduli are all along [1 1 0] plane, and the sequence of degree of anisotropic property is Li₁₇Ge₄ > Li₁₇Si_0.48Ge_3.52 > Li₁₇Si_0.92Ge_3.08 > Li₁₇Si_1.7Ge_2.3 > Li₁₇Si₄. The analysis of acoustic velocity shows that all the sound velocities decrease with the increasing Ge content for Li₁₇Si_4-xGe_x (x = 0, 2.3, 3.08, 3.53, and 4), and the longitudinal wave along [111] direction is fastest for the studied compounds. Debye temperature Θ_D, v_t and v_l decrease with the increasing Ge content. The minimum thermal conductivity decreases with the increasing Ge content, and Li₁₇Si_4-xGe_x have low thermal conductivities and are not potential thermal conductors. The analysis of electronic properties indicates that Li₁₇Si_4-xGe_x have the metal nature and anisotropic electrical conductivity. The electric conduction is improved with the increasing Ge content.     

浅析IPv6的发展和完善

阐述了IPv6是互联网向未来网络演进的必然选择,分析了IPv6在部署过程以及未来发展面临的挑战,指出了IPv6在部署后仍需在多个方面进行的技术演进和相关进展,以及IPv6与未来网络的关系。     

Control DSO6104L oscillograph to testing by PC via

本文就通过DSO6104L示波器的LAN接口实现网络控制问题,介绍了LAN Non-Auto-MDIX接口含义、计算机与DSO6104L的相连注意事项、LAN参数设置方法及充分利用其内部提供的远程前面板接口功能,通过Web浏览器实现控制类似于真实示波器仪器,不需要编写任何程序就可以达到远程控制的目的,该方法利用了仪器固有的资源,避免了资源浪费和无形的损失,可以直接利用其功能组建分布式测试系统,避免了程序设计和繁琐调试过程,对程序设计者和使用者具有很高的参考借鉴价值。     

关于全国无线电寻呼联网的基本设想

本文提出了全国无线电寻呼联网的基本设想和实现方案。     

IP网络的拓扑结构设计

对在设计IP网络的拓扑结构中涉及的网络分层，聚合、可靠冗余、IP地址分配等问题进行了探讨。     

用ADSP—21060芯片构建多处理器DSP系统

采用多处理器数字信号处理（ＤＳＰ）系统是现代数字信号处理技术发展的客观要求,这里介绍了用ＡＤＳＰ—２１０６０芯片作为ＣＰＵ来构建多处理器ＤＳＰ系统的设计实现方案。     

一种基于PCI总线的多路数据采集系统

结合对PCI总线接口控制芯片S5933的开发,详细介绍了基于PCI总线的一个多路数据采集系统,包括硬件时序和软件驱动程序的开发。最后给出一个用MatLab分析的实验结果,证明该系统性能良好。目前该系统已投入使用,工作稳定可靠。     

汉语单音节清晰度与STI-PA关系的实验测量

在实验室条件下对无噪声纯混响作用下STI—PA与汉语普通话单音节清晰度之间的关系进行了实验研究,归纳出了STI—PA与普通话单音节清晰度之间的函数关系。实验结果表明,汉语普通话单音节清晰度受混响的影响与基于外语的研究结果有所不同。     

Study of the trapping states in ZnS single crystals grown from gallium melt

The trapping levels in zinc sulphide single crystals grown from gallium melt have been investigated using thermoluminescence techniques. The observed peak at 175° K consists of two overlapping components at 173 and 200° K respectively. Thermal activation energies and frequency factors were calculated for both traps. The dependence of glow curve shape on excitation conditions is caused by the retrapping by non-filled 200° K traps of electrons freed from 173° K traps in the course of the glow curve run. In addition to the results on “pure” crystals, measurements were made on samples grown with chlorine, oxygen and copper impurities, as well. Although no positive identification of the chemical nature of the 173 and 200° K trapping centers has been possible, we find that our results are not inconsistent with a previously suggested model in which the traps are identified as complex defects. Comparison is also made with trap spectra observed earlier in gallium-doped zinc sulphide samples prepared by the usual methods.