Compared with different structure of P2P network,a new P2P e-Learning model based on Super Peer in distributed environment is presented.How a super peer is joined and what the service is of a super peer are described in this paper,as well as a detailed description of the data Ontology and Metadata of the e-Learning model.It also discusses the efficiency of the e-Learning model on file transfer issue.

文章从协同学的理论基础与支持协同学习的教学模式与方法出发,结合“编译原理”课程教学实践,探讨了在该课程中实施开放式协同学习教学模式的教学改革问题。针对课程的理论性强、内容抽象的特点,设计了新教学模式下编译原理课程的教学方案,给出实施开放式教学过程中重点解决的问题、编译原理实验教学指导以及教学效果评价方法。总结了协同学习教学模式的应用前景与意义。

水印系统通常被看作为一种通信模型,水印相当于被传送的信息,宿主信号为信道第一噪声源,攻击为信道第二噪声源。有信编码可以抵制第一噪声源对水印的干扰,而盲编码可以抵制第二噪声源的干扰。文章尝试性地提出了盲编码与有信编码结合的自适应的音频扩谱水印算法,用有信编码来抵制第一噪声源对水印的干扰,用较高码率的盲编码抵制第二噪声源的干扰。通过大量的实验证明,与其它的水印编码方案相比[3,4],该文的方法在多种攻击测试中具有很强的鲁棒性,其结果接近脏纸理论[7]的理想性能。

In this research an audio dual-watermarking scheme is presented in which both robust watermark and fragile watermark can be embedded.The robust watermarking is embedded in low-middle frequency range using the multi-resolution of DWT and the energy compression of DCT,while the fragile watermarking is rooted in high frequency range of wavelet domain.Watermark embedding is based on quantization process.The watermark can be extracted without the original digital audio signal.Experimental results show that the robustness of robust watermark is satisfying,and it can be applied to copyright protection,while fragile watermark is sensitive to audio attacks and can thus be utilized for content integrity verification.

数字水印已经成为实现多媒体版权保护的一项重要技术.提出在嵌入鲁棒性水印的同时考虑攻击的行为特征,辅以陷阱策略抵制各种攻击.水印以量化音频DCT系数的方式嵌入,在提取时针对攻击的行为特征以不同方式提取水印.算法嵌入的水印为一幅二值图像,能抵制随机裁剪、AD及DA转换、低通滤波等去同步型攻击,提取的水印可以直接分辨.与cocktail水印方法相比,所提方法的鲁棒性高,提取水印时不需要原始音频.实验结果说明我们的音频水印方法十分有效.

An audio watermarking algorithm based on mean quantization in the wavelet domain is presented.To reduce the effect of attacks on embedded watermark,mean quantization technique is used to embed the watermark.In this algorithm,the audio signal is decomposed using appropriate wavelet basis.Low frequency coefficients are selected to embed watermark using mean quantization method.The watermark can be extracted without the original digital audio signal.Experimental results show that compared with basic quantization watermarking algorithm,the algorithm presented in this paper is robust to many attacks,such as MP3 compression,requantization,resampling,low pass filtering,and noise addition and so on,and the robust performance has been improved highly.

本文在IEEE/ACM关于计算(Computing)学科本科教学参考计划CC2005(Computing Curricula 2005)指导下,针对我国高校本科计算机专业建设的现状,提出基于CC2005的"计算机组成原理与结构"课程内容体系的改革,采用整体"自顶向下"、细节"自底向上"的方法,从整机到部件、从原理到芯片的方式组织课程内容,并探讨了与课程群内部其他核心课程、选修课程之间的关系.

A wavelet speech enhancement algorithm based on Improved-Thresholding is presented.A parameter,which can be adjusted properly to produce the best estimations of the wavelet coefficients,is imported in the Improved-Thresolding function.The parameter enables the function to become a more general case in which it incorporates the hard and soft thresholding The experiments results show that this method can effectively enhance noisy speech infected by white Gaussian noise and reduce the loss of speech information.The enhancement of the SNR and the reduction of the MSE indicate that the performance of this method is better than the hard and soft thresholding methods.

An audio information hiding technology in DWT(discrete wavelet transform) domain based on chaotic map and modified Patchwork algorithm is presented.A piece of secret speech is hidden in the host audio signal,and can be recovered without loss.Two important characteristics of the chaotic sequence,high secrecy and easy reproducibility,are used to ensure operation security.In the modified Patchwork algorithm,a portion of DWT coefficients has been modified to make a shift of their statistical characteristic in order to hide the bit sequence of audio signals.The application of chaos and privacy of modification to DWT coefficients enhance the security of the algorithm.Blind recovery of the speech information is realized while keeping larger capacity of privacy information.Experimental results show that the SNR of the carrier audio after hiding is around 50dB,and the BER of the recovered bit stream is below 0.1%.This method is capable of ensuring audible quality of the carrier audio and the security of audio signals.

This paper presented an E-learning system model which is based on the Internet. This model adopts B/S three layer structure and ActiveX technology. In order to improve the response of the network, this model uses chinese word segmentation algorithm which is based on the max matching algorithm and the binary tree. This model is applied in distance education system of ckcsite.com.

With the development of multimedia technology and computer network, the distribution and transmission of digital media (e.g., image, text, audio and video) become very convenient. But rampant piracy, forgery and tamper is stunting the development of digital era. How to provide available method for copyright protection and information Security has become a hot research area. Digital watermarking as a copyright protection technology is developed in this condition. Digital audio watermarking is especially challenging compared with digital video and image watermarking because the human auditory system (HAS) is far more sensitive than the human visual system (HVS). An audio watermarking algorithm based-on Modulated Complex Lapped Transform (MCLT) is proposed. Using spectrum-warping technique that shifts spectrum coefficients non-linearly, a significant binary image is embedded in audio by modulating MCLT's angle frequency. In order to improve the security, some pretreatments for watermark are carried through before it is embedded to audio, such as repeat coding and interleaver. The watermarking is embedded in audio frequency domain, and embedding capability is high. The experimental results show that the spectrum-warping watermarking algorithm is of low robustness against MP3 compression, resampling and so on. It is a fragile watermarking algorithm.

A new audio digital watermarking blind algorithm based on MCLT coefficient quantization is presented. The embedded watermark is a visually recognizable image. After converting the binary watermark image into one-dimension sequence, the sequence is then modulated with m-sequence. Finally, the watermark is embedded into the audio signal by modifying the selected coefficients in the quantification process. The upper limit of quantization parameter is found by lots of listening test. Experimental results demonstrate that the embedding strategy is effective and the embedded watermark is inaudible and sustainable against compression algorithms, and common signal processing manipulation attacks.

文章提出了一种基于频率掩蔽效应的自适应音频数字水印算法.嵌入的水印为视觉可辨的二值图像,水印能根据音频信号的频域掩蔽阈值进行自适应调整,水印的提取采用假设检验的方法.实验结果表明所嵌入的水印是不可感知的,该算法对大多数音频信号处理具有很强的鲁棒性,如重采样、MP3压缩和随机裁剪等操作.

In order to enhance robustness, with the help of co nvolutional idea, the adaptive audio watermarking algorithm is investigated in D CT domain in this paper. The improved detecting algorithm which uses Viterbi sof t-decision is presented, and the watermark detecting doesnt need the original audio. Experimental results show that the proposed algorithm is provided with h igh robustness, and can resist signal processing manipulation attacks such as MP 3 compression algorithm.

随着互联网的发展,尤其是宽带网络的日益普及,越来越多的人选择远程教育.本文在分析远程教育需求的基础上,比较了目前几种远程教育模型的特点,并提出了一种基于Internet/Intranet的、同步模式与异步模式相结合的远程教学模型.

在研究教学模式的基础上,探讨了计算机组成原理课程的教学模式构建,结合课程的实际教学要求和教学方法,制定计算机组成原理课程的教学模式.