RM算法的运行时开销研究与算法改进

RM算法是经典的固定优先级实时调度算法.而在嵌入式实时系统中,系统的工作负荷往往是由很多频率快、执行时间较短的任务组成.因此,直接使用RM算法进行任务调度会由于实时操作系统中任务的上下文切换开销而导致嵌入式系统资源利用率的降低.分析了基于RM算法调度的任务之间的抢占关系,并建立了以任务属性为参数的上下文切换开销模型.在该模型的基础上,通过优化任务的释放时间来降低RM算法导致的系统运行时任务切换开销.最后的实验结果验证了该策略的有效性.     

嵌入式系统的低功耗与可靠性技术研究

本文中就主要点明了在工业化背景下嵌入式系统低功耗的建设需求,主要对嵌入式系统的实时低功耗技术原理以及系统类型进行全面剖析,最终重点研究了嵌入式系统基于平衡点的周期任务低功耗调度算法应用,结合实验分析论证嵌入式系统低功耗运行结果,希望提高系统运行可靠性。     

一种改进的进程调度算法在机顶盒上的设计与实现

调度算法对操作系统中的实时性起着关键的作用.就此问题,深入分析了基于最小优裕度算法的内核进程调度算法,为更好地满足Linux系统对嵌入式系统实时可靠性的要求,对现有的LSF调度策略进行分析,指出LSF算法调度算法的不足.为了改进LSF算法的颠簸现象,基于抢占阈值的思想,提出适用于LSF算法的抢占阈值分配方法,动态地给每...     

一种面向硬件线程的实时调度算法研究与设计

本文根据硬件线程的特征,为硬件线程调度建立了一个周期与非周期混合线程集的调度模型.在数学层面描述了硬件多线程调度中每个线程被成功调度的条件判据.并在此基础之上,提出一种以截止时间与最坏执行时间差为基本因子的DR-EDF算法,提供了一种实现这种DR-EDF算法的硬件多线程控制器的设计原理.最后用FPGA为载体,实现了一款硬件多线程处理器,通过实际测试的分析结果,得出这种面向硬件多线程的实时调度算法在不影响线程集错失率前提下,提高了嵌入式系统中紧急任务的可调度性.     

基于优化回溯模型的无重叠模调度算法

软件流水技术通过重组循环体来挖掘指令级并行性,模调度是一类广泛使用的软件流水调度算法.传统模调度算法通常会产生变量活跃域重叠和寄存器压力增大问题,无法适用于嵌入式处理器.本文面向嵌入式处理器特性,建立了一种优化回溯模型,并基于该回溯模型提出了一种面向嵌入式处理器的无重叠模调度算法(NOn-Over-lapped Iterative Modulo Scheduling,简称NOOI).NOOI算法使用循环相关反依赖消除变量活跃域重叠,并使用依赖约束和资源约束回溯模型消解节点冲突,从而提高了模调度的有效性.实验结果表明,NOOI模调度算法能够有效改进模调度成功率和循环启动间距,并提高程序性能.     

基于粒子群算法的嵌入式云计算资源调度

随着移动互联网的发展,基于嵌入式设备的云计算服务成为研究热点。在国内,嵌入式云计算目前正处于探索研究阶段,云资源管理调度是嵌入式云计算的核心技术之一,其效率直接影响嵌入式云计算系统的性能。为了提高云计算性能,本文提出一种基于粒子群优化算法的云计算任务调度模型。粒子群算法中粒子位置代表可行的资源调度方案,以云计算任务完成时间及资源负载均衡度作为目标函数,通过粒子群优化算法,找出最优资源调度方案。在matlab实验平台进行了仿真,通过大量数据模拟实验表明,该模型可以快速找到最优调度方案,提高资源利用率,具有较好的实用性和可行性。     

Linux的进程调度策略

随着Linux操作系统在嵌入式系统方面的应用越来越广泛,关于增强并改进Linux对实时任务支持方面的研究也越来越多.该文通过对Liunx下进程调度的原理、依据以及调度算法、实时调度策略的全面分析,说明了Linux对普通进程和实时进程进行相应处理的过程.同时为了改进Linux对实时任务的支持,提出了一种混合调度算法.     

CAN总线共享时钟调度算法的应用与改进

控制器局域网（CAN）协议被广泛运用在分布式嵌入式系统中,研究表明共享时钟调度算法能有效的将基于CAN的微控制器与时间触发网络结构结合起来。文章指出了共享时钟调度算法存在的一些不足,并且提出一种改进的共享时钟调度算法,通过构建一个实际系统验证了两种算法在CAN通信中的性能,结果显示改进的共享时钟调度算法是对原算法的一种有效补充。     

EDF调度算法抢占行为的研究及其改进

通过对采用抢占式EDF算法的嵌入式系统中各实时任务抢占行为的分析,建立了一个周期性任务集的抢占模型,从数学上描述了抢占关系、可调度性、调度开销与实时任务的周期、执行时间、最终期限、启动时间等属性之间的关系.依据该抢占模型,提出了一个改进的抢占式EDF调度算法,通过将基于遗传算法的优化方法离线计算得到的实时任务启动时间作为目标系统的一个调度参数,减少抢占次数,改变抢占关系,从而提高系统的可调度能力和实时性能.最后用实验验证了改进的抢占式EDF调度算法的有效性.     

ARINC653调度算法研究

实时调度算法是嵌入式系统的核心组成部分,高效的调度算法能增强系统的实时性和可靠性,ARINC653标准已经广泛地应用于综合航空电子系统中。首先介绍了几种实时调度算法,从满足ARINC653标准的角度出发,选取近几年的双层调度算法进行综述,讨论了现有的双层调度模型和双层调度算法,不同的分区间与分区内的调度算法组合会产生不同的效果。通过对各种双层模型和算法的比较与分析给出了各自的优缺点,对常用调度分析工具进行了叙述,以供设计和分析人员选择。最后,分析了双层调度算法有待深入研究的难点,并对其发展趋势进行展望。     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Nanoimprint Lithography -A Next Generation High Volume Lithography Technique

IntroductionNanoimprint Lithography is a well-acknowl-edged low cost, high resolution, large area pattern-ing process. It includes the most promising methods,high-pressure hot embossing lithography (HEL) [2],UV-cured imprinting (UV-NIL) [3] and micro contactprinting (m-CP, MCP) [4]. Curing of the imprintedstructures is either done by subsequent UV-lightexposure in the case of UV-NIL or by cooling downbelow the glass transition temperature of the ther-moplastic material in case of HEL…     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

Influence of PVK ： NPB hole transporting layer on the characteristics of organic light-emitting devices

A doping system consisting of NPB and PVK is employed as a composite hole transporting layer （CHTL）. By adjusting the component ratio of the doping system, a series of devices with different concentration proportion of PVK ： NPB are constracted. The result shows that doping concentration of NPB enhances the competence of hole transporting ability, and modifies the recombination region of charge as well as affects the surface morphology of doped film. Optimum device with a maximum brightness of 7852 cd/m^2 and a power efficiency of 1.75 lm/W has been obtained by choosing a concentration proportion of PVK ： NPB at 1：3.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.