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1.
郑玉甫 《信息技术》2008,32(3):106-108
通过混沌检测原理,得出了微弱余弦信号混沌检测模型,进一步利用VB设计和建立了微弱余弦信号混沌检测仿真系统平台.经与Matlab仿真实验比较验证其效果良好,与谱减法等检测结果进行比较证明该仿真系统平台具有优良的检测效果.这样不仅为混沌产生变化的研究提供了基础,同时也为混沌技术在实际信号检测中的应用提供了平台.  相似文献   

2.
设计了接触式印刷电路板检测系统,利用3个轴的步进电机驱动针头运动,对印刷电路板的电子线路的质量进行检测,并对其原理和具体的实现作了分析.通过实际应用证明,弥补了其他方案的不足,提高了检测效率.  相似文献   

3.
分布式拒绝服务攻击(Distributed Denial of Serviece Attack)是目前黑客用的比较多的攻击手段,这种攻击对网络造成的危害性越来越大.为了更好地了解这种攻击的特点,从而避免产生更大的损失,这里从DoS和DDoS的攻击原理进行探讨研究,研究常见的DDOS攻击的类型如Smurf攻击、Trinoo攻击等.根据这些攻击的特点,提出DDoS攻击的检测方法即基于特征的攻击检测和基于异常的攻击检测.这两种检测技术各有所长,在实际使用中往往需要将两者结合起来,共同提高DDoS检测的准确性.  相似文献   

4.
平稳随机过程非均匀采样信号的数字谱研究   总被引:6,自引:0,他引:6  
张洁  高品贤  林建辉 《信号处理》2002,18(4):358-362
目前的随机信号分析多是基于作等时间间隔采样以描述信号特征,而实际应用中往往不能避免采样的非均匀性;传统的谱分析方法必然产生原理误差。本文引入平稳随机点过程的知识,建立了广义平稳随机信号的非均匀采样序列模型,推导了其数字频谱的一般公式,分析了具有典型分布函数的随机采样情况。  相似文献   

5.
CCD动态检测轨道不平顺的研究及数据分析   总被引:2,自引:0,他引:2  
介绍基于CCD的动态检测轨道不平顺的方法,给出了系统检测的原理、总体结构和软件处理流程.装置经过实际线路的试验证明是准确和可靠的,文章对试验做了数据分析.  相似文献   

6.
木马是目前计算机网络面临的主要安全威胁之一.针对现有木马检测方法的不足,提出了行为分析与ID3决策树相结合的木马动态检测技术,对其原理、算法、实现和性能进行了详细介绍.利用ID3算法对样本进行学习建立的木马判定决策树,根据程序运行时的行为判定其是否为木马.在Windows系统下的实现和测试显示该技术具有较高的准确率.  相似文献   

7.
基于线阵CCD的光刻机调焦调平系统的研究   总被引:1,自引:0,他引:1  
介绍了一种基于线阵CCD的光刻机调焦调平系统,讨论了其检测和控制原理.介绍了调焦调平系统的光学结构,并建立起了理想的单点高度测量与整场调焦调平的算法模型.  相似文献   

8.
传统多用户检测方法通常假定接收方已知活跃用户数,其一般为这个系统所能容纳的最大用户个数.在此前提下,传统多用户检测方法能够获得较好的性能.然而在实际多址移动通信系统中活跃用户个数及其参数往往都是时变的,因此传统多用户检测方法性能恶化.针对这个问题,本文首先采用随机集理论( Random Set Theory,RST)建立多用户动态模型,基于此模型将信道分解为离散部分和连续部分,并通过分析两者的关系得到它们的状态转移概率;然后提出了采用Rao-Blackwellised粒子滤波(RBPF)算法的时变多用户检测器,实现了活跃用户数目变化和信道幅度变化的跟踪及用户发送数据估计;最后给出了算法在抗噪声能力、抗远近效应和系统容量等方面的仿真结果.仿真结果表明本文算法性能明显优于传统多用户检测方法.  相似文献   

9.
基于DSP的雷达目标检测模块设计   总被引:1,自引:1,他引:0  
高性能信号处理器芯片ADSP-TS101广泛应用于复杂雷达信号处理系统的设计中.本文分析了动目标检测(MTD)和恒虚警检测(CFAR)的原理,对其性能进行了讨论,并根据实际情况做了算法改进和优化,最后在基于四TS101雷达信号处理板上完成系统的设计实现.  相似文献   

10.
田立勤  林闯 《电子学报》2003,31(Z1):2167-2170
工作流是近年来网络领域里研究的一个热点,对工作流模型的性能分析是工作流研究的一个重要内容.实际的模型往往规模大而复杂,这为分析其性能带来了很大的困难.但有一类模型可由工作流的四种基本模型(顺序、并行、选择、循环)嵌套组成,对于这类模型,本文给出了计算其性能乘积解的数学公式.文中给出了如何由这四种基本模型嵌套组成实际模型的方法,推导出了计算这四种基本模型的性能等价公式,并按建立实际模型相反的顺序,用由里到外逐层的分析方法,给出了计算实际模型的性能乘积解.  相似文献   

11.
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.  相似文献   

12.
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.  相似文献   

13.
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.  相似文献   

14.
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.  相似文献   

15.
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.  相似文献   

16.
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.  相似文献   

17.
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.  相似文献   

18.
It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output(MIMO) communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.  相似文献   

19.
The effect of laser microbeam trapping the bioparticles has been appfied widely in the biology .However the micromechanism of the acting that realizes the laser-microbeam trapping bioparticles is still lacking. In this paper ,the act microchenism of the gradiant force of laser microbeam for the bioparticles is analysed by means of quantum theory ,The result accords with our experiment.  相似文献   

20.
Using multiple importance sampling (MIS) technique, the optical communication system performance affected by polarization-mode dispersion (PMD) and polarization-dependent loss (PDL) is simulated numerically. The power penalties and system outage probabilities are obtained for optical communication systems with on-off keying (OOK) or differential phase shift keying (DPSK) modulation. The simulation results show that DPSK always performs better than OOK. When the system has moderate PDL (about 1.5 dB), it is necessary to compensate effectively the fiber PMD in order to enhance the system tolerance to the PMD and PDL. However, the efficiency of PMD compensation will degrade rapidly when the PMD of the whole optical link drops into the low value.  相似文献   

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