基于Tinyos的低功耗MAC协议研究

由于无线传感器网络中的能量有限的特性,所以降低节点能耗,延长网络寿命在无线传感器网络中显得十分重要。低功耗的无线传感器网络协议,是无线传感器网络在应用中的一项重要技术。本文从无线传感器网络能耗方面出发,对BMAC、XMAC的优缺点进行了详细分析、提出了一个改进,并且基于Tinyos平台进行了实验,验证了低功耗协议良好的能耗特性。     

无线传感器网络自适应目标跟踪节点调度算法

在无线传感器网络中,设计合理的节点调度算法是提高网络感知能力、降低系统能耗的关键。在分析节点能耗模型的基础上,针对移动目标跟踪型网络应用,提出一种高能效的无线传感器网络自适应节点调度算法ANSTT。该算法根据节点对移动目标的感知能力,以及节点的相对剩余能量水平,自动调整节点工作模式。仿真实验表明,ANSTT算法在维持低感知延时、高目标感知率的同时,可有效降低系统能耗,延长网络寿命。     

传感器网络中的节点能耗监测软件设计与实现

为了有效延长节点工作寿命,设计一种新型的传感器网络节点能耗监测软件。传感器网络节点能耗监测系统的硬件主要由FPGA和控制板组成,所设计的软件将针对二者的工作流程进行控制。FPGA使用软件给出的采集程序和节点能耗识别码,进行传感器网络节点能耗数据的持续采集和模数转换。被转换成数字信号的节点能耗数据将被采集程序封装并传输到控制板。控制板根据数据读取流程对封装数据进行重构,获取完整的节点能耗数据并进行解析,给出节点能耗调节建议,实现对传感器网络节点能耗的监测。经实验验证可知,所设计的软件监测距离较远、传感节点工作寿命延长性能颇佳。     

无线传感器网络能耗分析与策略研究

无线传感器网络技术得到了广泛应用,但是该技术一直受能量的制约,因此能量始终是无线传感器网络的核心问题。通过对传感器节点结构与网络体系的分析,得出了传感器网络的能耗特性。为了延长无线传感器网络的生命周期,对传感器节点工作能耗与传感网络能耗做了具体研究,再从低功耗节点设计、网络协议及环境中能量补给三个方面总结出了一套有效的节能策略。     

基于CC2530的无线传感器节点的设计及性能分析

针对人力成本较高的现状和传统的有线监测系统布线繁杂、监测灵活性差及以往无线传感器节点能耗较高等问题,介绍了一种新型的无线传感器节点的结构和工作性能。综合利用太阳能供电技术、传感技术和无线通信技术,设计了一种依靠太阳能自主供电的无线传感器节点,有效解决了传感节点能耗的问题。经测试,人机交互操作简单,节点可靠性高,可以满足环境参数采集和监测工作的要求。     

改进的无线传感器节点定位算法

由于无线传感器网络具有其它网络不可比拟的各种优势,使得它在很多领域都有广泛的应用。对于无线传感器网络中的未知节点本身的定位工作是网络的各项应用的基础。本文主要分析无线传感器网络的节点定位技术,研究已有的定位算法,并根据现有算法提出一种改进的分布式的节点定位算法。该算法使用RSSI方法测距,无需增加新的硬件设备,通过分布式的算法来提高效率降低能耗,利用多次定位的平均值提高定位精度,降低了网络中的能量消耗,延长网络寿命。     

一种无线传感器网络全连通群的休眠调度算法

该文针对无线传感器网络的覆盖性和连通性问题,在假设传感器节点地理位置信息已知的条件下,设计了一种包含全连通群的建立和维护以及群内节点休眠调度的全新算法。该算法采用保证群内节点彼此一跳可达的全连通群分群方法,以及分布式节能的休眠调度策略,最大程度上减少传感器网络的能量消耗,延长了网络寿命。仿真结果表明:该算法能较好地保证无线传感器网络的覆盖性和连通性,且能耗较低。     

毫微功率能量收集IC极大地延长电池寿命

历史上,远程无线传感器一直依靠电池供电来测量数据并以无线方式发送数据。这种方式一直工作可靠,但传感器网络的可用寿命取决于电池的可用寿命。在有些应用中,无线传感器节点是人员可及的,因此电池可以相对容易地更换,尽管会有一些费用。这些电池设计为持续工作5～10年时间,在每个传感器节点中,都属于昂贵的组件。     

中继节点解决无线传感器网络的能量空洞问题

由于无线传感器网络多对一的数据传输特性,距sink节点近的传感器节点由于承担的数据量增大而过早的死亡,形成能量空洞。文章在近SINK节点区域额外布设专门用来转发数据的中继节点,降低了近SINK节点的传感器节点的数据量,达到了均衡整个网络能耗的目的,延长了网络寿命。     

基于ARM7的无线传感器网络节点能量管理初探

为了研究无线传感器网络能量管理和组网技术,采用ARM基高性能、低功耗微控制器LPC2138为核心制作了一种新型无线传感器网络节点,该节点由两节AA电池供电。说明了该节点的硬件构成及设计方法,介绍了该无线传感器网络节点使用的电池模型,并给出了一组该节点有效工作状态下的功率。     

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.