24 bit高精度数据采集系统接口电路的FPGA实现

采用VHDL语言设计，用FPGA解决了GS5381与DSP之间接口电路复杂、难以实现的问题。完成了多路模拟信号的同步高精度模／数转换、数据预处理、中断、数据缓存等电路的设计。本方案外围电路结构简单可靠，特别适用于高精度数据采集系统中，而且可以根据需要易于对系统进行扩展，有一定的通用性。实际应用系统中，输出信号的动态范围接近100dB，在弱信号的测量中，有很高的推广价值。     

24Bit高精度数据采集系统接口电路的FPGA实现

CS5381是一种24竹高性能以体声∑-△A/D变换器，该器件仪具有串行数据总线（I^2C），故与DSP器件的接口电路较为复杂。文章给出了基于VHDL语言实现的多片CS5381与DSP之间的接口电路、数据缓冲存储电路、以及系统实验结果。实际应用系统中，该系统的输出信号动态范围接近100dB。[编者按]     

工厂线路越级跳闸事故案例分析及级差保护配合方案

工厂供电系统多采用电缆线路,其截面大、长度短,给线路保护级差配合增加了难度,在线路末端出现短路故障时易造成越级跳闸事故发生。为此,针对某110kV新建变电站出现的越级跳闸事故,对各线路保护定值时间重新进行校验,为下级出线留出时间配合空间,以满足保护选择性要求。     

基于建筑施工图设计管理的优化策略

建筑施工图纸的设计效果的影响因素相对较多,由于施工图纸设计具有很强的综合性和技术性,因此在实际设计中需要结合建筑工程的特点和要求,明确施工图设计管理的内容,为提升理水平,促使建筑工程施工中各道工序都能高效、有序地开展,本文以西安金科博翠天宸项目为例,通过对建筑施工图设计管理内容,分析了当前设计管理中常见的问题,提出建筑施工图设计管理的优化策略,研究表明：施工图纸设计管理效果直接关系到整个建筑工程项目施工质量和效率。因此,对建筑施工图设计管理的优化策略的研究具有十分重要的意义。     

一种改进的小波阈值去噪法

基于小波变换的阈值去噪法是去除数字信号中白噪声的有效算法,其中阈值函数的选择关系着重构信号的连续性和精度。但是硬阈值函数在阈值点具有不连续性,软阈值函数中估计的小波系数与信号的小波信号间存在恒定偏差的缺陷,这些缺点限制了阈值去噪法的进一步应用。将硬阈值和软阈值函数进行加权平均,选取适当的权值函数,可以构造出一种克服了软硬阈值缺点的新的阈值函数。仿真结果表明,该方法具有较好的去噪效果。     

Optical Emission Spectroscopic Studies of ICP Ar Plasma

The ion line of 434.8 nm and atom line of 419.8 nm of Ar plasma produced by an inductively coupled plasma （ICP） were measured by optical emission spectroscopy and the influences from the working gas pressure, radio-frequency （RF） power and different positions in the discharge chamber on the line intensities were investigated in this study. It was found that the intensity of Ar atom line increased firstly and then saturated with the increase of the pressure. The line intensity of Ar^＋, on the other hand, reached a maximum value and then decreased along with the pressure. The intensity of the line in an RF discharge also demonstrated a jumping mode and a hysteresis phenomenon with the RF power. When the RF power increased to 400 W, the discharge jumped from the E-mode to the H-mode where the line intensity of Ar atom demonstrated a sudden increase, while the intensity of Ar^＋ ion only changed slightly. If the RF power decreased from a high value, e.g., 1000 W, the discharge would jump from the H-mode back to the E-mode at a power of 300 W. At this time the intensities of Ar and Ar^＋ lines would also decrease sharply. It was also noticed in this paper that the intensity of the ion line depended on the detective location in the chamber, namely at the bottom of the chamber the line was more intense than that in the middle of the chamber, but less intense than at the top, which is considered to be related to the capacitance coupling ability of the ICP plasma in different discharge areas.     

Cu Films Deposited by Unbalanced Magnetron Sputtering Enhanced by ICP and External Magnetic Field Confinement

Metallic copper（Cu） films were deposited on a Si （100） substrate by unbalanced magnetron sputtering enhanced by radio-frequency plasma and external magnetic field confinement. The morphology and structure of the films were examined by scanning electron microscopy （SEM）, atomic force microscope （AFM） and X-ray diffraction （XRD）. The surface average roughness of the deposited Cu films was characterized by AFM data and resistivity was measured by a four-point probe. The results show that the Cu films deposited with radio-frequency discharge enhanced ionization and external magnetic field confinement have a smooth surface, low surface roughness and low resistivity. The reasons may be that the radio-frequency discharge and external magnetic field enhance the plasma density, which further improves the ion bombardment effect under the same bias voltage conditions. Ion bombardment can obviously influence the growth features and characteristics of the deposited Cu films.     

射频等离子体增强非平衡磁控溅射沉积技术

介绍了射频电感耦合等离子体增强非平衡磁控溅射沉积技术的原理、实验性能。并用该技术在Si基片上沉积了Cu膜，研究了所成膜的结构、表面形貌及膜成分等，分析结果表明在该条件下沉积的Cu膜致密，晶粒尺度大约在100～1000nm，膜基界面比较紧密，没有明显的空洞，并且膜呈（111）织构。最后简要介绍了该技术应用的前景。     

小波阈值去噪法的改进算法

基于小波变换的阈值去噪法是去除数字信号中白噪声的有效算法.其中阈值函数关系着重构信号的连续性和精度,硬阈值函数的不连续性和软阈值函数中估计的小波系数与信号的小波信号间存在恒定偏差的缺陷,也限制了它的进一步应用.本文通过数学方法的引入,对阈值函数进行了改进.仿真结果表明,该方法具有较好的去噪效果.