基于片上PowerPC的Vxworks处理平台的波束控制设计

片上嵌入式系统凭借其诸多方面的优势,如成本低、功耗低、尺寸小、处理速度快、可靠性高、实时性强、灵活性、产品上市时间以及设计开发周期短等优势,将嵌入式实时多任务操作系统VxWorks和基于FPGA的片上PowerPC平台相结合,使产品体积更小、环境适应性更强、运行更可靠、扩展和升级更灵活、生产成本更低。必将成为将来雷达产品上的主流技术。本文提出了在其内嵌PowerPC440处理器上构建Vxworks操作系统平台的雷达的波束控制设计。     

基于预测极性动态变换的分支预测框架研究

针对动态分支预测错误率在时间上分布不均匀且高错误率比较集中的特点,该文提出一种可动态变换预测极性的分支预测方法。该方法对未经极性变换的原始动态分支预测错误率进行自适应监测,筛选出原始动态分支预测错误率高于阈值的预测错误高峰期,进而调整预测错误高峰期内分支预测器的预测极性,使经过极性变换的最终动态分支预测错误率在程序运行过程中始终低于设定的阈值。该文同时研究了全局监测、按组监测和局部监测3种分支预测错误率监测方式。实验结果表明,相同硬件资源下该方法比Gshare和Bi-Mode分支预测方法具有更高的分支预测精度。     

A study on the temperature dependence of epoxy/BaTiO<Subscript>3</Subscript> composite embedded capacitor films

In this study, the temperature dependence of capacitance, one of the most important properties of embedded capacitor films (ECFs), was investigated. The temperature dependence of the capacitance of ECFs was determined by the temperature dependence of the dielectric constant and thickness, and among these, the main factor was the dielectric constant of ECFs. The dielectric constant of ECFs was determined by that of epoxy and BaTiO₃ powders. Below 130°C, the dielectric constant of ECFs increased as temperature increased, and was mainly affected by an epoxy matrix. However, above 130°C (the Curie temperature of BaTiO₃), the increased rate of the dielectric constant of ECFs started decreasing. This was due to the fact that BaTiO₃ powder undergoes a phase transition from a tetragonal to a cubic structure, and its dielectric constant decreases at 130°C. The dielectric constant of BaTiO₃ powder was obtained from measured dielectric constants of ECF and application of the Lichtenecker logarithmic rule.     

“嵌埋式实时操作系统”灵活性的研究

本文阐述了“嵌埋式实时操作系统”灵活性的三个因素；可移植性、可配置性、可剪裁性及其概念和重要性，并提出了一些设计和实现的方法。     

Samba图形化配置工具的设计与实现

针对Linux系统下配置Samba共享服务只能通过用户手动编辑配置文件,且配置项众多、步骤繁琐、上手困难等问题,分析了Samba配置文件的结构和配置项的具体作用,结合重载Samba配置和使配置生效的相关系统指令,通过Python的OS库执行系统命令,设计了基于Python的Samba配置解析算法,解析系统中已存在的Sa...     

On simplified solutions of contact problems for elastic foundations

In the paper, a method of averaging displacements in a circular area lying in a linearly elastic transversally isotropic foundation is developed for the four modes of motion: vertical, horizontal, rocking and torsional. The corresponding formulae are constructed in a general form which does not depend on the kind of Green functions. For vertical and horizontal modes, uniform load distribution are applied and the simple integral mean is considered, whereas for rotational modes the load proportional to the distance from an axis of rotation is used, and angles of rotation for individual points are averaged with weight of the distance squared. Along with the case of equal radii of circles of loading and averaging, the case of different radii is studied, which allows one to consider contact problems for embedded axisymmetric foundations having the radius varying with depth. As examples the following contact problems are studied: static stiffness for a cone embedded in a homogeneous isotropic half-space in vertical motion, and dynamic stiffness for a disk on a layer resting on a homogeneous half-space for four modes of motion. Comparisons with the corresponding exact solutions are carried out.     

数字投影三维数字成像的并行DSP实现

提出一种基于数字白光投影的三维数字成像嵌入式DSP处理系统.该系统根据时序变频条纹投影原理,利用TMS320DM642定点DSP和FPGA硬件电路以及多线程软件技术实现了条纹编码、编码图像采集和条纹分析的流水线处理过程.为了提高相位解调算法的速度,使用软件流水对其进行了优化.对于512×512像素图像,五步相移时的条纹图处理速度可达到39.7 fps,能满足快速条纹图处理的要求.测量实验表明,该系统可以实现快速、准确的三维轮廓测量.     

Embedded dots inside glass for optical film using UV laser of ultrafast laser pulse

Microstructures are usually fabricated on the surface of optical sheets to improve the optical characteristics. In this study, a new fabrication process with UV (ultraviolet) laser direct writing method is developed to embed microstructures inside the glass. Then the optical properties of glass such as reflection and refraction indexes can be modified. Single- and multi-layer microstructures are designed and embedded inside glass substrate to modify the optical characteristics. Both luminance and uniformity can be controlled with the embedded microstructures. Thus, the glass with inside pattern can be used as a light guide plate to increase optical performance. First, an optical commercial software, FRED, is applied to design the microstructure configuration. Then, UV laser direct writing with output power 2.5-2.6 W, repetition rate 30 kHz, wave length: 355 nm, and pulse duration 15 ns is used to fabricate the microstructures inside the glass. The effect of dot pattern in the glass such as the dot pitch, the layer gap, and the number of layer on the optical performance is discussed. Machining capacity of UV laser ranges from micron to submicrometer; hence with this ultrafast laser pulse, objectives of various dimensions such as dot, line width, and layers can be easily embedded in the glass by one simple process. In addition, the embedded microstructures can be made with less contamination. Finally, the optical performance of the glasses with various configurations is measured using a Spectra Colorometer (Photo Research PR650) and compared with the simulated results.