一种基于K-means的WSN移动汇聚路由算法

无线传感网络(Wireless Sensor Network,WSN)作为一种资源受限的网络,网络中节点的能耗直接影响了网络的性能。因此,均衡网络中的能耗,延长网络的生命周期,成为设计WSN路由算法的重要目标。于是,在LEACH-C协议的基础上提出了一种移动汇聚路由算法。分簇阶段由Sink节点计算最优簇首个数,通过K-means聚类将网络中的节点划分至不同的集群,选择通信成本最低的节点作为各集群的簇首。稳定传输阶段通过移动Sink进行数据采集,针对不同的延迟分别规划Sink节点的移动轨迹。MATLAB仿真结果表明,与LEACH和LEAHC-C算法相比簇首的分布更合理,结合Sink节点的移动策略能有效均衡网络能耗,延长网络的寿命。     

基于提前选择策略的传感器网络的分层路由协议

能量的有限性严重限制了无线传感器网络的发展,而数据冗余问题在分层路由协议中广泛存在,网络的密度越高,数据冗余问题越严重.现介绍一种新的方法来解决这个问题.在群建立之前从网络中选取一些已分配的节点,而这些操作类似于群首节点的选取过程,这些被选取的节点将用来完成整个网络的数据融合过程.仿真结果分析表明采用了这种策略之后网络生存期延长了很多.     

一种基于能量和区域密度的LEACH算法的改进

本文在LEACH算法的基础上,引入节点剩余能量、节点到汇聚节点的距离和区域内节点密度等因素.利用网络最小能量来求解出最佳的簇首节点个数,动态设置每个节点的选举阈值.仿真实验表明,本文改进算法相较于LEACH算法和其它改进算法可以有效地降低网络能耗,延长网络生命周期,提高汇聚节点接收数据包量.     

无线传感器网络泊松分布最优簇首数目的研究

在无线传感器网络分簇路由协议中,簇首节点通常会消耗更多的能量。簇首节点过多或过少都会增加网络能耗。因此,为延长整个网络的生存周期,需要合理设置簇首节点的个数。在节点服从二维泊松分布的基础上,为最小化网络能耗,提出了一种求解网络最优簇首数目的方法。网络仿真表明,簇首个数为最优簇首数时,整个网络能量消耗最低。将求解的最优簇首数用于LEACH协议中,不仅延长了第一个节点的死亡时间,也提高了整个网络的生存周期。     

低能量自适应分群分层协议的改进

为了避免能量较少节点当选为群首而过早死亡,对Leach协议群首的选取进行改进。采用结合节点剩余能量重新设置阈值的方法,选取剩余能量较多的节点作为群首,解决了能量较少节点当选为群首和群首负担载过重的问题。仿真结果表明,采用改进后的算法可以有效减少网络能量的消耗,延长网络生存时间。     

基于扇形分簇的无线传感器网络路由算法

无线传感网络中低功耗自适应聚类分簇(LEACH)路由算法等概率选取簇首节点,容易导致整个网络节点能量损耗出现极端化,减少网络生存时间。为此,提出一种针对簇首节点选取和分簇的改进LEACH算法。该算法把整个网络区域分为四个扇形区域,在每个区域内独立进行分簇路由;然后基站根据节点剩余能量和与基站的距离进行簇首节点选择,节点根据簇首节点和基站接收信号强度选择路由方式,以均衡网络能量消耗。仿真结果表明,改进LEACH算法的网络寿命是原有LEACH算法的150%,数据吞吐量提升了3倍。     

基于权值竞争的分簇与连通策略研究

针对无线传感器网络中节点失效导致网络断连的问题,提出一种基于分簇和路径规划的网络连通策略,适用于命令监控型监测。固定节点采用权值竞选机制选举出最佳数量的簇首,其余节点根据簇首信号强度成簇;移动节点连通各簇首与汇点（sink）,借鉴动态旅行商问题的数学模型,尽快遍历所有簇首。两者共同维护无线传感器网络全连通。仿真结果表明：分簇算法显著增加网络运行轮数,路径规划降低网络的数据丢失率。     

基于融合补偿的光纤网络入侵节点精准定位策略

光纤网络节点受到入侵后易导致信息丢失，甚至导致整体网络系统瘫痪。为此，提出基于融合补偿的光纤网络入侵节点精准定位策略方法。利用汇聚链路的控制法分组检测网络节点并融合信息，利用融合滤波的控制方法，获取网络入侵节点与未被入侵节点的差异化特性，确定关键节点位置，选择最佳公共节点补偿，满足节点对网络拓扑改变的最小原则，凭借信号分析法提取网络内异常信息特征，构建光纤网络入侵节点信号波束模型，提供定位输入数据，最后对整体网络状态预处理，建立网络检测模型，将异常特征信息输入至粒子群算法中，完成光纤网络入侵节点精准定位。实验结果表明：所提方法对入侵节点定位耗时较短，且定位平均误差较低。     

一种针对无线传感器网络LEACH协议的改进算法

针对传统LEACH协议在簇首选取的随意性,以及簇首节点将数据以单跳形式传输给汇聚节点造成能耗大的缺点。文中提出了改进协议,该算法在对簇头节点的选择时会将节点的剩余能量考虑进去,会在选择剩余能量最多,同时以其到汇聚节点距离小的节点作为下一跳来传输数据,以实现多个簇之间的路由数据传输。通过Matlab仿真可以知道,改进后的协议使整个传感器网络的能量消耗变得更加均衡,同时使整个网络的生存时间得到了15%的延长。     

非正交多址中继系统复数域网络编码优化设计

无线中继与网络编码是提高通信系统数据可靠性和吞吐率的重要技术手段,重点研究了单中继非正交多址系统复数域网络编码的优化设计问题.首先,在限制源节点和中继节点的总发送功率并假设各个源节点发送功率相同的条件下,证明了当源节点与中继节点发送功率相等时基于复数域网络编码的单中继非正交多址系统误符号率(SEP)性能最佳.其次,以编码增益为目标函数,提出了一种复数域网络编码的优化设计方法.与已有的复数域网络编码系数设计方法相比,此方法能满足任意源节点个数条件下复数域网络编码系数的优化设计要求,同时可以有效地避免因为网络编码系数选择不当造成信号重叠的现象,提升和改进系统的SEP性能.     

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.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

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.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

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.     

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.