社会网络中基于局部信息的边社区挖掘

 近年来,随着社交网络的发展,许多重叠社区挖掘算法被提出来.传统的方法都是将节点作为研究对象,而最近的一些研究表明,以边为研究对象的边社区挖掘方法相对于点社区挖掘方法来说具有更加明显的优势.因此,我们提出了基于局部边社区的挖掘算法(LLCM),利用网络中的局部信息去挖掘边社区结构.给定一条初始的边,通过不断最大化一个适应度函数来获取该边所在的局部社区,而这条初始的边可以预先通过一些排序算法进行选择.算法经过在计算机生成网络和真实网络上测试,并且同其他边社区挖掘算法进行了比较,实验结果表明LLCM算法获取了合理的边社区的结构.     

基于双编码的重叠社团检测多目标优化方法

近年来,多目标进化方法已被广泛应用于重叠社团检测问题并取得了较好的社团划分性能.如何设计合适的个体编码以及进化策略是提高基于多目标进化重叠社团检测算法性能的重要因素.为此,本文设计了一种双编码表示方法对非重叠社团结构和重叠点分别进行编码,能够有效解码得到重叠社团结构.在双编码表示的基础上,本文提出了一种基于双编码的重叠社团检测多目标优化方法(DRMOEA).在DRMOEA中,为了获得好的初始个体并提高算法检测性能,本文提出了一种基于社团边界点的初始化策略.除此之外,针对双编码中的重叠点编码部分,本文提出了基于精英个体边界点的交叉策略,该策略利用社团边界信息引导种群向好的方向进化,从而有效提高了算法的检测性能.最后,在9个真实世界网络上的实验结果表明DRMOEA算法优于其他5个代表性重叠社团检测算法.     

基于LSGA的最小测试用例集自动生成

测试数据的生成是一个复杂的问题且其技术和方法还不成熟.根据实现语句覆盖的测试目标,提出了最大稳定遗传算法（LSGA）.该算法充分考虑了遗传算法的稳定性并在构造适应度函数和路径编号时提出了＂邻近者优先＂原则和＂就近路径编号＂原则.这个算法可以生成满足测试目标的最小用例集且其性能明显优于遗传算法.     

一种基于神经网络的广义熵模糊聚类算法

以模糊聚类为基础,将广义熵引入到模糊聚类的目标函数中,提出一种基于模糊熵的模糊聚类的统一形式,即广义熵模糊聚类模型;利用增广拉格朗日求解方法,以及Hopfield神经网络和复突触神经网络解决了基于广义熵的目标函数的优化问题,提出了基于神经网络的广义熵模糊聚类算法,表明了使用神经网络求解的收敛性;同时,给出一种用于确定增广拉格朗日乘子的迭代方法.实验中选取人工生成数据集和UCI标准数据集对提出的算法进行了实验研究,并与常用的聚类算法进行了性能比较.     

在流滑动窗体上挖掘Top-K高效用项集的有效算法

数据流上的频繁项集挖掘是数据挖掘的一个重要话题,并在现实生活中应用广泛.可是这个问题存在两个限制:(1)项在数据流中的权重没有被考虑;(2)项在每条事务中的数量没有被考虑.因此,研究人员提出了"数据流上的高效用项集挖掘"的研究问题.在这一问题中,项的权重及项在事务中的数量被考虑,数据流上的高效用项集挖掘是指在数据流中挖掘所有效用值不小于用户指定最小效用阈值的项集.对用户而言,由于不了解数据流中数据的统计特性,很难设置一个合适的最小效用阈值,如果最小效用阈值设置过高,则挖掘算法返回高效用项集的数量过少,使得用户无法准确分析;如果最小效用阈值设置过低,则挖掘算法返回太多的高效用项集,使得用户需要对结果集二次分析,为此研究人员提出了"数据流上的Top-K高效用项集挖掘"的研究问题.数据流上的Top-K高效用项集挖掘是指在数据流中寻找前k个具有最高效用值的项集,通过设置k值取代最小效用阈值,可有效地控制算法的输出规模,对用户而言更直观.与静态数据相比,数据流具有如下特点:快速的数据到达速率、数据流的尺寸未知和不能访问以前到达数据的特点,因此很难将整个数据流放入内存中处理,通常研究人员采用流滑动窗体模型.流滑动窗体是由固定数量的、最近到达的批数据组成,每个批数据包含一组事务集.现有的挖掘流滑动窗体上Top-K高效用项集的研究方法通常包含两个阶段:(1)采用高估技术高估项集在流滑动窗体中的效用,将高估效用不小于由阈值提升技术获得的最小效用阈值的项集选定为Top-K高效用项集候选项集;(2)通过扫描流滑动窗体内的批数据,计算第一阶段生成的候选项集的真实效用.可是,这个方法存在两个问题:(1)第一阶段生成的候选项集通常数量巨大,需要大量的存储空间;(2)计算第一阶段生成的候选项集的真实效用是非常耗时的.因此,本文提出一个在挖掘过程中不生成候选项集的流滑动窗体上Top-K高效用项集挖掘算法TK-HIS,TK-HIS采用提出的HUIL-Tree和效用数据库存储流滑动窗体中的项集及其在窗体事务中的效用,在HUIL-Tree和效用数据库的构建过程中提出两个阈值提升策略提升初始值为0的最小效用阈值,在挖掘过程中TK-HIS维护前k个具有最高效用值的项集,使用模式增长的方法生成搜索空间中的项集,对每一个项集通过效用数据库直接计算其在流滑动窗体中的效用.研究在稀疏数据流上进行了大量的实验评估TK-HIS的性能,并与当前最好的流滑动窗体Top-K高效用项集挖掘算法T-HUDS进行比较,实验结果表明在稀疏数据流上TK-HIS显著优于T-HUDS:运行时间最快可提升一个数量级.     

多基站数据聚合无线传感器网络中的最大生命期路由

研究了多基站数据聚合无线传感器网络中的最大生命期路由问题.首先证明该类问题具有NP-hard性质,然后提出一种基于最小生成森林的启发式算法,并采用次梯度方法设计了分布式算法,最后通过大量的仿真实验分析所提路由算法性能,并给出分布式算法的收敛性能.     

基于Mean Shift算法非刚体跟踪的性能分析

介绍一种通过目标特征提取和定位实现的自下而上的运动物体跟踪方法,并通过实验对其性能进行分析和研究.该方法首先对某帧图像中的目标对象进行核函数空域加权的像素直方图特征提取.将目标对象的定位问题等价变换为在空域中求最优解的问题.通过Mean Shift算法在空域对相似程度求最优解,找到与目标对象模式最相似的搜索对象模式,从而完成目标对象的定位.在此通过仿真实验对Mean Shift算法在非刚性目标跟踪应用上的适用性、鲁棒性以及实时性进行分析和研究.最后还提出一些对该方法的改进算法.     

激光测高仪中雪崩光电二极管的探测性能分析

光电探测器是影响激光测高仪探测性能的重要器件.为了使探测器性能保持最佳状态,采用了近似算法进行分析.该算法使用近似分布函数来模拟探测器的输出,推导出虚警率与阈值门限和倍增因子三者之间的函数关系,找出虚警率、阈值和增益之间的最佳结合点.实验表明,根据该方法设计的激光测高仪探测器接收电路,可使探测概率和回波信噪比有显著提高.这一结果对激光测高仪目标特性的回波分析和地形地貌3维轮廓重建有很大帮助.     

基于最小生成树的并行分层聚类算法

分层聚类技术在图像处理、入侵检测和生物信息学等方面有着极为重要的应用,是数据挖掘领域的研究热点之一.针对目前基于SIMD模型的并行分层聚类算法存在的无法解决存储冲突问题,提出一种基于最小生成树无存取冲突的并行分层聚类算法.算法使用O(p)个并行处理单元,在O(n2/p)的时间内对n个输入数据点进行聚类,与现有文献结论进行的性能对比分析表明,本算法明显改进了现有文献的研究结果,是一种无存储冲突的并行分层聚类算法.     

基于核主分量相关判别分析特征提取方法的目标HRRP识别

为有效提高雷达高分辨1维距离像目标识别系统的总体性能,需要对目标高分辨1维距离像进行特征提取,以得到具有最小信息损失、高可分性且低维度的目标特征,为实现该目的提出一种基于核主分量相关判别分析的特征提取算法。该算法基于目标高分辨1维距离像的统计特性,通过对核主分量分析中核函数的选择,实现对不同类型距离单元的特征提取。同时综合线性判别分析与典型相关分析理论构建新的准则函数,以实现特征空间中类内相关性与类间差异性最大化,同时减少目标特征中的冗余信息。利用实测数据进行实验,结果表明该方法提高了特征向量的可分性,降低了特征向量的维度,并且对该算法在不同强度杂波下的识别性能进行了分析,实验结果表明,该方法可以有效的提高目标高分辨1维距离像目标识别系统的总体性能。     

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.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.