Memory-constrained Block Processing for DSP Software Optimization

Digital signal processing (DSP) applications involve processing long streams of input data. It is important to take into account this form of processing when implementing embedded software for DSP systems. Task-level vectorization, or block processing, is a useful dataflow graph transformation that can significantly improve execution performance by allowing subsequences of data items to be processed through individual task invocations. In this way, several benefits can be obtained, including reduced context switch overhead, increased memory locality, improved utilization of processor pipelines, and use of more efficient DSP oriented addressing modes. On the other hand, block processing generally results in increased memory requirements since it effectively increases the sizes of the input and output values associated with processing tasks. In this paper, we investigate the memory-performance trade-off associated with block processing. We develop novel block processing algorithms that carefully take into account memory constraints to achieve efficient block processing configurations within given memory space limitations. Our experimental results indicate that these methods derive optimal memory-constrained block processing solutions most of the time. We demonstrate the advantages of our block processing techniques on practical kernel functions and applications in the DSP domain.

Excluded Minors and the Ribbon Graphs of Knots

In this article we consider minors of ribbon graphs (or, equivalently, cellularly embedded graphs). The theory of minors of ribbon graphs differs from that of graphs in that contracting loops is necessary and doing this can create additional vertices and components. Thus, the ribbon graph minor relation is incompatible with the graph minor relation. We discuss excluded minor characterizations of minor closed families of ribbon graphs. Our main result is an excluded minor characterization of the family of ribbon graphs that represent knot and link diagrams.     

基于MPC8548E的嵌入式实时系统自举优化设计

板级支持包(BSP)是嵌入式系统中联系操作系统与硬件平台的桥梁。以PowerPC体系架构下 的MPC8548E的微处理器硬件为平台,研究了VxWorks操作系统的启动过程,并从BSP的总体架 构 、存储空间的地址分配、运行过程等方面进行分析,提出了一种新的策略来优化实时操作系 统启动时间,通过实验证明此方法可行且安全,具有一定的适用性。     

Self-interstitial configuration in molybdenum studied by modified analytical embedded atom method

The stability of various atomic configurations containing a self-interstitial atom (SIA) in a model representing Mo has been investigated using the modified analytical embedded atom method (MAEAM). The lattice relaxations are treated with the molecular dynamics (MD) simulation at absolute zero of temperature. Six relatively stable self-interstitial configurations and formation energies have been described and calculated. The results indicate that the [111] dumbbell interstitial S₁₁₁ has the lowest formation energy, and in ascending order, the sequence of the configurations is predicted to be S₁₁₁, C, S₁₁₀, T, S₀₀₁ and O. From relaxed displacement field up to the fifth-NN atoms of six configurations, we know that the relaxed displacements depend not only on separation distances of the NN atoms from the defect centre but also strongly on the direction of the connected line between the NN atoms and the defect centre. The equilibrium distances between two nearest atoms in the core of the S₁₁₁, C, S₁₁₀, T, S₀₀₁ and O configurations are 0.72a, 0.72a, 0.71a, 0.72a, 0.70a and 0.70a, respectively.      

Variational formulation of the material failure process in solids by embedded discontinuities model

This work presents a variational formulation of the material failure process, idealized as strain or displacement discontinuities, by weak, strong, or discrete embedded discontinuities into a continuum. It is shown that the solution of the proposed variational formulation may be approximated by different types of finite elements with embedded discontinuities. The developed displacement approximation of a finite element split by the discontinuity leads to a symmetric stiffness matrix, which considers not only the continuity of tractions but also the rigid body relative motions of the portions in which the element is split. The variational formulation of a continuum with more than one discontinuity in its interior is developed. It is shown that this formulation may lead to finite elements with embedded discontinuities that can be classified as displacement, force, mixed, and hybrid models. To show the effectiveness of the proposed formulation, the classical example of a bar under tension is solved using one and 2D finite element approximations. © 2008 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2009     

短波发射机智能控制系统的设计与实现

随着工业自动化的普及与发展,为了实现短波发射机全自动化,要求有更加先进、稳定、可靠的设备加入到控制系统中,在这里采用了智能控制系统终端,即集合信息技术、计算机技术、控制技术为一体的控制模块,实际中对短波发射机进行了控制方面的改造,最后获得了很好的自动化控制效果,解决了工作人员的手工操作,完全可以做到无人化值班无人化控制。为未来的一体化全智能控制打下技术基础。     

基于嵌入式的虚拟仪器构件问题的研究

由于微电子技术、计算机技术的飞速发展,对电量的测量以及模拟技术也相应的提高,虚拟仪器技术的提出大大简便了计算机测试测量与控制。文中针对虚拟仪器技术中的虚拟仪器构件问题,利用嵌入式的思想进行了简单的分析。     

基于超声波的头部动作侦测设计

基于Intel大学项目,完成三维增强显示系统中对于用户头部动作以及位置数据的检测与传输功能。介绍超声测距原理,利用嵌入式ARM处理器来完成对于系统的控制与数据传输,完成了头部动作侦测的设计,并且验证了该系统的实用性与稳定性。     

基于四网协同的智能家居系统的设计

国内无线城市的建设已如火如荼地开展,各运营商根据各自运营网络的特点,从不同则重点给出了若干建设方案.针对中国移动良好的网络覆盖优势,并以中国移动“四网协同”发展战略为契机,顺应国内移动互联网和云计算产业浪潮的兴起,探讨使用新型系统级数字信号处理器做核心,借助嵌入式Internet 技术及获工信部十二五发展规划政策扶持的物联网技术,搭建一体化的安全、舒适、绿色环保的智能家居系统.     

基于K60＋FPGA的小型移动机器人硬件设计

本文介绍了一种基于K60N512处理器和FPGA的嵌入式移动机器人平台,并具体分析了各个模块在硬件上的设计和实现。机器人平台采用模块化的分层结构设计,充分发挥了ARM与FPGA各自的特点,并提供有丰富的外设和接口,具有良好的通用性和可扩展性,为本文以后的工作提供了良好的基础硬件平台。