数字水印技术研究

数字水印技术作为一种信息安全技术,是在数字信息中加入不可见的标记,从而实现数字产品的版权保护。本文全面分析总结了数字水印的模型与特性,详细讨论了多种数字水印算法,并分析了这些算法的适用范围。最后,文章给出了数字水印未来的发展与研究方向。     

网络信息安全和数字水印技术

网络信息安全是网络安全的核心,其主要技术包括监控、检测、加密、认证以及数字水印技术等等.数字水印具有不可感知性、隐蔽性与安全性以及鲁棒性.数字水印技术广泛应用于数字产品的版权保护、声像数据的隐藏标识和篡改提示以及隐蔽通信等等.     

数字水印嵌入算法分析

数字水印是近年出现的一种数字产品版权保护技术,它可携带有版权信息和认证信息,保护数字产品的合法拷贝和传播,已经成为当前国际学术界的研究热点.本文主要探讨了数字水印原理、特点、一般模型和典型算法.     

一种基于CDMA和HVS的数字水印算法

数字水印技术是解决信息安全和数字媒体的版权保护的一种有效手段.笔者将CDMA技术引入数字水印技术中,提出一种基于CDMA(Code Division Multiple Access)和HVS(人类视觉系统)的灰度图像数字水印算法.该算法采用CDMA扩频技术对水印信息进行正交化处理提高安全性,并在将水印信息嵌入原始灰度图像时充分考虑了人眼的视觉特征.实验证明该算法具有良好的鲁棒性和不可见性,是一种有效的方法.     

数字水印协议研究

数字水印技术为数字产品的知识产权保护提供了一种工具,但是仅靠技术的成熟远远不能达到目的,在这种情况下就出现了数字水印协议的研究.本文介绍了安全数字水印体系的概念,IMPRIMATUR体系以及现有的数字水印协议.最后对当前数字水印协议的状况进行了总结.     

网络信息安全和数字水印技术

网络信息安全是网络安全的核心,其主要技术包括监控、检测、加密、认证以及数字水印技术等等。数字水印具有不可感知性、隐蔽性与安全性以及鲁棒性。数字水印技术广泛应用于数字产品的版权保护、声像数据的隐藏标识和篡改提示以及隐蔽通信等等。     

扩频技术在数字图像水印技术中的应用及分析

数字水印技术作为数字产品版权保护的一种新技术,已受到越来越多的关注.为了提高水印的安全性,把扩频技术应用到数字水印中,分析了扩频技术的原理及优点.最后通过实验证明,该方法对剪裁、JPEG压缩和噪声等图像退化处理均具有一定的抵抗力,是一种行之有效的水印嵌入方法.     

基于数字水印技术的档案安全保护手段

分析了数字档案的信息安全隐患及对策,介绍了数字档案的版权保护手段——数字水印技术,阐述了基于数字水印技术的档案信息安全方案。     

数字水印技术及其攻击分析

如何保护数字产品的版权在多媒体信息交流日益广泛和网络日益普及的今天受到人们的高度重视,成为一个迫切需要解决好的课题.作为信息隐藏技术的一个重要分支,数字水印技术将成为保护数字作品版权的重要手段.文章对多媒体数字水印技术的原理及其基本特征、现有方法作了详细的论述,重点分析了几种数字水印算法方案和攻击手段,指出了应用中存在的问题,并展望了未来研究方向.     

数字水印技术的发展与展望

在信息时代的今天,我们可以很方便地通过网络来获取、交流信息,传统媒体正逐渐被数字媒体所替代,这也使得数字媒体的复制、篡改等问题渐渐出现,网络与信息安全等问题变得日趋重要。本文介绍了数字水印技术的概念、基本特征和分类,数字水印技术的现状、开发中的应用及其局限性,并对未来数字水印技术的前景以及发展提出了自己的观点。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with