基于数据包分析的网页还原技术研究

本文结合应用环境和实际需求,研究了网络数据包信息还原涉及的数据包捕获技术、数据包分析技术、数据包重组技术、http信息识别技术。     

一种用于网络攻击犯罪防范的数据包分配防护方法

网络攻击犯罪被认为是目前影响网络尤其是因特网安全的重要威胁之一,传统的数据包分配防护算法采用线性组合重传方式进行网络攻击犯罪的防范。但网络环境的波动性,使得接收方对信息产生的负反馈效应,导致数据包分配防护算法的均衡性差。提出一种用于网络攻击犯罪防范的数据包分配防护方法。采用分布式计算方法,并融合于随机网络编码方法,获取无线网络数据包的编码解码线性方程,利用方程中网络节点信息反馈机制,编码解码并优化重组网络数据包,提高网络数据包的分配防护性能。仿真结果表明,采用该算法有效降低无线网络数据包的分配误比特率,提高了网络数据包分配防护均衡性能,能够较好地应用于网络攻击犯罪的防范中。     

基于DSP的语音识别系统研究

文章介绍了语音识别的基本原理以及用DSK6713实现语音识别算法的一些原则和方法,阐述了语音识别在DSP上的实现技术。系统使用梅尔倒谱系数（MFCC）作为特征参数,采用算法相对简单以及计算量较小的动态时间弯折算法（DTW）实现语音参数的匹配。用MATLAB实现DTW算法的仿真,进而将语音识别技术应用到DSP上,实验结果表明对特定人、小词汇量和孤立词的语音识别效果比较好。     

基于窄带VoIP网络的说话人识别

在语音同一鉴定案件中,自动语音识别方法逐渐被采用,但目前某些语音检材存在质量下降无法进行有效语音识别等问题。文章通过研究网络电话（VoIP）各特性因素（如语音编解码、数据包丢失、数据包乱序、网络抖动和外来串扰或回波）,对自动语音识别系统（ASR）性能的影响做出系统分析。     

识别现代藏文基字的算法设计与实现

识别藏文单音节的基字是藏文排序的基础,识别算法的劣质直接影响到藏文排序的速度和效率。文章在对藏文编码体系和藏文单音节本身的语法特点进行研究的基础上,设计一种识别藏文单音节基字的算法,经试验表明已达到较高的准确率。     

IP追踪中一种新的确定性包标记方法

本文提出一种新的确定性包标记(NDPM)方法.它通过边界网关协议(BGP)路由器在其转发的数据包中标记IP地址信息和当前AS编号,受害者不仅可根据数据包中的标记信息追踪到攻击源所在的AS,还可以根据标记信息过滤掉攻击包,从而能有效地缓解攻击流量对受害者的影响.该方法解决了传统标记算法中计算量大、误报率高等缺点,同时无须攻击路径中每个路由器都参与标记,极大地减少了路由器开销.     

隐通道网络波动下数据包监测间隔测量算法

传统的数据包监测间隔测量算法采用概率统计为基础的链接数配对方法,由于网络链接时间段,隐通道网络波动幅度大,监测时间间隔测量不准。提出一种C/S架构隐通道网络波动下基于有界抖动范围内均匀分布的数据包监测间隔测量算法,基于有界波动范围内均匀分布的数据包监测间隔测量,优化通道容量和抗检测性之间的关系,调整接收方测量时间间隔与发送方发送的时间间隔,使其达到一致。仿真实验表明,采用该方法能有效避免网络波动的影响,通过调整监测间隔时间步长,使得数据包传输误码率降低为0,规避了网络波动影响,提高了C/S隐通道网络通信性能。     

网络协议分析技术研究

通过对TCP/IP协议的相关知识的深入理解,人们就可以对捕获到的数据包进行协议分析工作,还原数据包所封装的协议结构和其携带的数据,从而得到大量有价值的信息。     

一种以DPI为核心的网络流量识别方案

网络流量的识别是流量控制、计费和内容安全等需求实现的前提条件,是适应当前网络急速增长和解决当前网络威胁的有效途径。提出了一种以深度数据包检测（DeepPacketInspection,DPI）为主要识别技术,结合端口、统计等多种识别技术的识别方案。以谷歌的GoogleTalk为例,对各种场景的应用和采用不同协议的情况,进行了细致的分析。测试结果表明,该方案能精确地识别各种类型的协议。     

人体行走特征识别研究

针对运动状态下人体步态的特征识别,本文采用了一种基于轮廓的方法对步态特征进行提取,先把目标从背景中分离出来,再提取人的整体轮廓,本文中所提取的人在行走过程中的特征就是人的质心点到轮廓边缘各个像素点之间的距离。然后使用BP神经网络算法根据步态数据库进行步态识别。结果表明,本文中的步态识别算法准确率优于其他算法。     

DES加密算法及其在Java中的实现

DES算法已被应用于许多需要安全加密的场合(如信用卡持卡人的PIN加密传输、IC卡与POS间的双向认证、金融数据包校验等),深入地分析了DES算法的思想、加密过程及应用,并指出了DES算法的优势和不足。     

基于小波包分解的数字图像水印算法研究

通过Shannon熵算法采用自下向上的搜索方法选取最优小波包基,分别对原始图像和水印图像进行小波包分解,把水印数据嵌入选定的原始图像小波包基中。经攻击实验表明,应用本算法所实现的水印不可见,较好地保持了图像的质量,同时显示了较强的鲁棒性。     

动态概率包标记算法分析及改进

IP追踪技术是防御拒绝服务攻击的一个研究热点。本文对IP追踪中的动态概率包标记算法进行了介绍和分析,在总结其优点的同时也发现其存在不足。针对动态概率包标记算法使得距离攻击者最近的边界路由器的标记负载太大的不足提出了一个可行性改进方案,经对比分析效果明显。     

网络处理器的程序设计方法

在网络节点处理串行数据流时，通常将数据流处理功能构造为单向或双向的内部高速输入输出系统，分析其特征可知：它们的数据包处理流程和程序设计方法基本相同，但网络处理器的速度和带宽不相同。本文以IPv6典型的数据包处理流程为例，重点探讨IXP2XXX网络处理器的数据结构和操作过程、微引擎缟程模型和程序设计方法。     

网络排队策略优化的OPNET仿真研究

移动通信技术的迅速发展,越来越需要各种网络技术的全面支持与融合。基于这个原因,就路由器传递数据包的排队策略对移动通讯系统的服务质量进行了研究,并利用OPNET软件进行了仿真。结果表明,采用wFQ策略,接口每次按不同的权重从不同队列中取不同数量的数据包发送,能优化路由器的数据吞吐量。     

Helping ants for adaptive network routing

Appropriate routing in data transfer is a challenging problem that can lead to improved performance of networks in terms of lower delay in delivery of packets and higher throughput. Considering the highly distributed nature of networks, several multi-agent based algorithms, and in particular ant colony based algorithms, have been suggested in recent years. However, considering the need for quick optimization and adaptation to network changes, improving the relative slow convergence of these algorithms remains an elusive challenge. Our goal here is to reduce the time needed for convergence and to accelerate the routing algorithm's response to network failures and/or changes by imitating pheromone propagation in natural ant colonies. More specifically, information exchange among neighboring nodes is facilitated by proposing a new type of ant (helping ants) to the AntNet algorithm. The resulting algorithm, the “modified AntNet,” is then simulated via NS2 on NSF network topology. The network performance is evaluated under various node-failure and node-added conditions. Statistical analysis of results confirms that the new method can significantly reduce the average packet delivery time and rate of convergence to the optimal route when compared with standard AntNet.     

VxWorks系统下的Intel82559ER驱动程序设计

Intel82559ER是在嵌入式系统中广泛使用的功能最为强大的快速以太网控制器之一,在网口数据流量很大,且CPU占用率不能过高的情况下,设计一个高效率的驱动程序显得尤为重要。本文基于VxWorks的软件平台和MPC8241CPU的硬件平台,提出一种新的Intel82559ER快速以太网控制器驱动程序设计方法,该方法将中断与查询相结合,既提高了网口处理数据包的能力,又避免了CPU占用率过高。     

An on-line orthogonal wavelet denoising algorithm for high-resolution surface scans

This paper deals with noise detection and threshold free on-line denoising procedure for discrete scanning probe microscopy (SPM) surface images using wavelets. In this sense, the proposed denoising procedure works without thresholds for the localisation of noise, as well for the stop criterium of the algorithm. In particular, a proposition which states a constructive structural property of the wavelets tree with respect to a defined seminorm has been proven for a special technical case. Using orthogonal wavelets, it is possible to obtain an efficient localisation of noise and as a consequence a denoising of the measured signal. An on-line denoising algorithm, which is based upon the discrete wavelet transform (DWT), is proposed to detect unavoidable measured noise in the acquired data. With the help of a seminorm the noise of a signal is defined as an incoherent part of a measured signal and it is possible to rearrange the wavelet basis which can illuminate the differences between its coherent and incoherent part. In effect, the procedure looks for the subspaces consisting of wavelet packets characterised either by small or opposing components in the wavelet domain. Taking real measurements the effectiveness of the proposed denoising algorithm is validated and compared with Gaussian FIR- and Median filter. The proposed method was built using the free wavelet toolboxes from the WaveLab 850 library of the Stanford University (USA).     

一种二用户协作HARQ通信方案

针对协作通信(cooperative communication)的重传问题,提出了在2个用户和基站之间的通信过程中,用户之间如何协作进行混合ARQ(hybrid ARQ)的方案. 通过分时发送机制,每个用户都保存对方上一次发送的数据,在收到基站的ACK/NACK后,根据基站的指示,从存储的上一次发送数据包中,寻找需要重传的数据包,并插入自己需要传送的新数据包,在下一个发送时隙中进行传输. 通过协作通信系统所实现的空间分集增益,提高了HARQ的性能. 比较2个用户分别独立与基站通信和相互协作与基站通信的HARQ方案,并通过理论分析和仿真,比较不同信噪比(SNR)下的吞吐量(throughput)和误包率(PER)以及平均时延,证实了本系统在可提高系统传输时延的前提下,具有更高的吞吐量和更低的PER.     

Biorthogonal wavelet trees in the classification of embedded signal classes for intelligent sensors using machine learning applications

The paper deals with a method of constructing orthonormal bases of coordinates which maximize, through redundant dictionaries (frames) of biorthogonal bases, a class separability index or distances among classes. The method proposes an algorithm which consists of biorthogonal expansions over two redundant dictionaries. Embedded classes are often present in multiclassification problems. It is shown how the biorthogonality of the expansion can really help to construct a coordinate system which characterizes the classes. The algorithm is created for training wavelet networks in order to provide an efficient coordinate system maximizing the Cross Entropy function between two complementary classes. Sine and cosine wavelet packets are basis functions of the network. Thanks to their packet structure, once selected the depth of the tree, an adaptive number of basis functions is automatically chosen. The algorithm is also able to carry out centering and dilation of the basis functions in an adaptive way. The algorithm works with a preliminary extracted feature through shrinkage technique in order to reduce the dimensionality of the problem. In particular, our attention is pointed out for time-frequency monitoring, detection and classification of transients in rail vehicle systems and the outlier problem. In the former case the goal is to distinguish transients as inrush current and no inrush current and a further distinction between the two complementary classes: dangerous inrush current and no dangerous inrush current. The proposed algorithm is used on line in order to recognize the dangerous transients in real time and thus shut-down the vehicle. The algorithm can also be used in a general application of the outlier detection. A similar structure is used in developed algorithms which are currently integrated in the inferential modeling platform of the unit responsible for Advanced Control and Simulation Solutions within ABB's (Asea Brown Boveri) industry division. It is shown how impressive and rapid performances are achieved with a limited number of wavelets and few iterations. Real applications using real measured data are included to illustrate and analyze the effectiveness of the proposed method.