多线程的效率

用Java语言定义了一个线程类,并用System类中的静态方法eurrentTimeMillis()计算时间,从而比较了用不同个数的线程求数组元素和的时间.通过实验证明在LimLx、Windows 2000 Advanced Server和Windows XPProfessional系统中,在加数个数一定的条件下,并不是线程数越多,效率越高.而是要用合适的线程数.同时通过分析了在Windows XP Professional中,不同配置的计算机线程个教与加数的关系相似.     

智能公用室内照明系统的设计

分析比较了已有的几种智能照明系统方案,将检测单元阵列引入智能公用室内照明系统的设计中,从而实现了可精确定位使用者位置及检测此位置的自然光水平,进而实现照明灯的精确控制,实现了真正的智能照明。实际应用验证了本文所述方法的可行性,根据室内自然光及使用者情况自动进行智能照明控制可达到节能目的,且方便操作管理,具有很好的应用前景。     

图像处理技术在面包烘焙品质检验中的应用

阐速了数字图像处理技术在烘焙面包品质检验中的应用,依据灰度共现矩阵算法提取图像的纹理特征,并通过二值化后的烘焙面包切片计算出其体积。试验结果表明,该方法不仅为面包烘焙品质的快速自动检验提供了客观准确的科学依据,使感官评价的指标客观化,而且经济可行。     

BGA焊点气孔缺陷的特殊结构光质量检测

为了解决球栅阵列（BGA）焊点气孔缺陷的在线检测问题,开发了一种特殊的结构光检测技术。同时用环形红光和十字形绿光发射二极管（LED）照明BGA芯片,通过环形和十字形的中心,布置一个带有远心透镜的电荷耦合器（CCD）摄像机记录小球上红色圆环和绿色十字的图像。根据图像半径方向上的纹理频谱分布特征,引入人工神经网络（ANN）算法对BGA芯片的气孔缺陷进行检测。采用真实的BGA焊点进行实验,结果验证了方法的精度和可行性。     

Orbital pairing effects in fullerenes

We propose a theory of superconductivity for a crystal having multiple band structure. The theory is valid for the parameter(k _F)/1 when the splitting between bands(k _F ) is small in comparison with the phonon frequency. The theory may be applicable to the doped fullerenes where it is widely supposed that pairing occurs through high-energy intramolecular phonons. As in semiconductors, the bunch of bands is treated by ascribing the highest spin to electrons. We derive the analytic expression for the critical temperature, which strongly depends on the value of the total spin of the Cooper pair, which may be equal toY=0,1,.... In all cases the order parameter is a vector with components proportional to spherical harmonics and at the same time the superconducting gap has no zeros. The data may be fitted to doped fullerenes, if the superconductivity arises fromd-pairing.     

A variable-precision square root implementation for field programmable gate arrays

Applications requiring variable-precision arithmetic often rely on software implementations because custom hardware is either unavailable or too costly to build. By using the flexibility of the Xilinx XC4010 field programmable gate arrays, we present a hardware implementation of square root that is easily tailored to any desired precision. Our design consists of three types of modules: a control logic module, a data path module to extend the precision in 4-bit increments, and an interface module to span multiple chips. Our data path design avoids the common problem of large fan-out delay in the critical path. Cycle time is independent of precision, and operation latency can be independent of interchip communication delays.Notation S_j square root digit of weight 2^–j - S _j {–1, 0, 1} - S[j] computed square root value as of stepj - S _j ^s sign bit in the representation ofS _j in sign and magnitude form - S _j ^m magnitude bit in the representation ofS _j in sign and magnitude form - w[j] residual at stepj in two's complement carry-save representation - a sum vector in the carry-save representation of 2w[j] - b carry vector in the carry-save representation of 2w[j] - a _i bit of weight 2^–i in the sum vector,a - b_i bit of weight 2^–i in the carry vector,b - T[j]=–S[j – 1]s_j – s _j ² 2^–(j+1) T _i bit of weight 2^–i inT     

Maximum Power Extraction Control Algorithm for Hybrid Renewable Energy System

In this research, a modified fractional order proportional integral derivate (FOPID) control method is proposed for the photovoltaic (PV) and thermoelectric generator (TEG) combined hybrid renewable energy system. The faster tracking and steady-state output are aimed at the suggested maximum power point tracking (MPPT) control technique. The derivative order number (µ) value in the improved FOPID (also known as PI^λD^µ) control structure will be dynamically updated utilizing the value of change in PV array voltage output. During the transient, the value of µ is changeable; it’s one at the start and after reaching the maximum power point (MPP), allowing for strong tracking characteristics. TEG will use the freely available waste thermal energy created surrounding the PV array for additional power generation, increasing the system’s energy conversion efficiency. A high-gain DC-DC converter circuit is included in the system to maintain a high amplitude DC input voltage to the inverter circuit. The proposed approach’s performance was investigated using an extensive MATLAB software simulation and validated by comparing findings with the perturbation and observation (P&O) type MPPT control method. The study results demonstrate that the FOPID controller-based MPPT control outperforms the P&O method in harvesting the maximum power achievable from the PV-TEG hybrid source. There is also a better control action and a faster response.     

基于改进的GABP算法优化5G天线阵列

为了加快天线建模速度,针对现有天线设计软件天线参数优化速度过慢问题进行了建模研究。首先通过几种常用的启发式算法优化后的多层前馈（Back propagation,BP）神经网络对天线参数进行优化比较,并对其中最优的算法遗传算法优化BP（Genetic algorithm BP,GABP）神经网络算法进行深度改进。其次采用自适应算法和模拟退火算法优化算法对GABP进行优化。最终通过模拟试验验证出自适应GABP算法对于天线参数优化的误差最小。该研究为天线设计软件中天线优化方法提供了一种误差较小的新方法,拥有更高的预测准确度,拟合速度也大大提升。实验对比证明了该算法的可行性。     

二进制代码安全分析综述

近几十年来,计算机硬件性能和软件规模技术已不同以往,其承载了人类社会生活生产的方方面面.计算机技术的飞速发展,也带来了人们对程序安全问题的关注.由于市面上存在着较多的遗留软件,这些软件无人维护且缺乏源代码支持,其安全性令人担忧,而二进制分析技术被用来解决该类软件问题.二进制分析技术根据其检测方式不同可分为:基于静态的二进制代码分析技术、基于动态的二进制代码分析技术和动静态混合的二进制代码分析技术.本文调研了近年来的二进制代码安全分析领域上相关研究,分别详细阐述了这3类技术中的主要方法,并对其关键技术进行详细介绍.     

混响噪声下声源定位与跟踪的多特征自适应IMM粒子滤波算法EI北大核心CSCD

针对混响噪声下声源定位精度低和鲁棒性弱等问题,提出了多特征自适应IMM粒子滤波算法.该算法以麦克风接收信号的多特征作为观测信息,采用空时相关和迭代滤波建立了时延选择机制和波束输出能量优化机制,并在两者的基础上构建了似然函数以获得合理的声源位置信息.考虑到说话人运动的随机性,给出了自适应IMM算法,通过在线粒子集生成并将不同过程方差的模型进行交互来拟合说话人的不同运动模式,改善了说话人跟踪系统的稳健性.仿真和实测结果表明,所提算法利用了多特征定位信息的互补性,降低了观测误差不确定性对声源位置估计的影响,增强了随机运动声源跟踪系统的鲁棒性,提高了系统的定位精度.