一种基于混合蛙跳优化的JPEG图像隐写算法

在JPEG图像中隐写会引起图像DCT系数直方图变化和分块效应比,分析者可以根据这些特征变化察觉到秘密信息的存在。为了提高隐写的安全性,提出了一种基于混合蛙跳优化的JPEG图像隐写算法。对图像进行分块处理后,在每个块中采用混合蛙跳优化算法,寻找最优的置换矩阵来替换秘密信息。在隐写过程中,将置换矩阵和置换后的秘密信息隐藏于修改了量化表的DCT系数中,算法不需传递其他边缘信息。仿真实验表明,所提出的隐写算法与修改量化表隐写算法,基于粒子群优化隐写算法相比,在隐写容量增大的同时,具有更高的安全性。     

基于直方图差异的模型隐写分析

基于模型(Model-Based,MB)的隐写方法可以保持JPEG载体图像的直方图在隐写前后几乎不变,使秘密信息具有良好的统计隐蔽性.根据MB隐写使得图像平坦区域和纹理区域的DCT系数分布变得相似这一线索,提出一种新的隐写分析方法,通过考察纹理较丰富的内容中的DCT系数直方图与全局DCT系数直方图之间的差异情况来分析图像是否经过MB隐写.实验结果表明,该方法可有效击破MB隐写.     

基于DCT系数修改的自适应稳健可逆信息隐藏

通过修改JPEG图像块中的DCT系数, 提出一种新的稳健可逆信息隐藏方法. 遍历块中特定位置连续6个DCT系数的均值, 找出最接近0的均值进行嵌入. 由于连续DCT系数的均值接近0, 经过压缩操作不会有太大的变化, 因此所嵌入的秘密信息有一定的稳健性. 为了对抗攻击, 在嵌入秘密信息时, 通过比较并改变系数的大小, 将改变量分为两个等级进行自适应嵌入. 若含密图像未被压缩, 则不仅可以正确提取秘密信息, 而且可以恢复原始图像; 若含密图像已被压缩, 则只能正确提取秘密信息, 不能恢复原始图像. 实验结果表明, 在经过质量因子为85以上的压缩攻击后, 含密图像的视觉效果很好, 并且仍能正确提取秘密信息.     

不同扫描方式在联合图像专家小组隐写分析方法中的应用

目前绝大部分联合图像专家小组(joint photographic experts group,JPEG)隐写方法都是通过改变DCT系数值来实现秘密信息嵌入;这种嵌入方式必然会对DCT系数的相关性造成影响,在隐写分析时挖掘DCT系数相关性很有必要。共生矩阵是挖掘DCT系数相关性的常用工具,利用该工具在提取特征前需要先对系数进行扫描。现有主流JPEG隐写分析方法主要采用行扫描或列扫描,对其他扫描方式研究较少,没有充分挖掘DCT系数相关性。针对这个问题,在研究不同扫描方式后,提出了一种新的JPEG隐写分析方法;该方法首先分析了不同扫描方式对DCT系数的块间和块内相关性的影响,然后使用多种高阶共生矩阵提取DCT系数在不同方向和距离上的相关性作为特征。针对4种隐写方法 11种嵌入率的实验表明,与同类型的低维特征方法相比,该方法的检测正确率有明显提升;与同类型的高维特征方法相比,在不明显降低检测正确率的情况下,能使得特征维数得到有效控制,综合性能有一定提升。     

不同扫描方式在JPEG隐写分析方法中的研究与应用

目前绝大部分JPEG隐写方法都是通过改变DCT系数值来实现秘密信息嵌入,这种嵌入方式必然会对DCT系数的相关性造成影响,在隐写分析时挖掘DCT系数相关性很有必要。共生矩阵是挖掘DCT系数相关性的常用工具,利用该工具在提取特征前需要先对系数进行扫描。现有主流JPEG隐写分析方法主要采用行扫描或列扫描,对其他扫描方式研究较少,没有充分挖掘DCT系数相关性。针对这个问题,该文在研究不同扫描方式后,提出了一种新的JPEG隐写分析方法。该方法首先分析了不同扫描方式对DCT系数的块间和块内相关性的影响,然后使用多种高阶共生矩阵提取DCT系数在不同方向和距离上的相关性作为特征。针对4种隐写方法11种嵌入率的实验表明,与同类型的低维特征方法相比,该方法的检测正确率有明显提升,与同类型的高维特征方法相比,在不明显降低检测正确率的情况下,能使得特征维数得到有效控制,综合性能有一定提升。     

基于分块的JPEG图像信息隐藏算法

本文将图像进行分块,根据每块图像量化后的DCT系数矩阵,结合视觉特性将图像块分为不同的类型;然后对不同类型的块采用不同的方法在AC系数中嵌入秘密信息,减少对载体图像的影响,隐藏信息后载体图像块的类型不变,从而可正确提取隐藏信息.实验结果表明,该算法在保持JPEG图像视觉质量的同时有较高信息隐藏容量.     

一种JPEG图像可逆视觉变换算法

可逆视觉变换是一种新兴的图像处理技术,能够在改变图像视觉内容后无失真地恢复原始图像,用于秘密图像加密传输等场景.文中首次提出了一种基于JPEG压缩的图像可逆视觉变换算法,具有适用性强、计算复杂度低等特点.由于JPEG格式是当前应用较多的图像类型之一,研究JPEG图像中的数据隐藏和可逆视觉变换技术具有重要实用价值.算法通过改变DCT系数矩阵中最后4位系数以嵌入图像子块位置索引信息,能够根据提取的数据无失真地还原出原始图像.实验结果表明,文中算法能改变秘密图像的视觉内容,并实现可逆的图像视觉变换,无需额外信息即可完全恢复原始的JPEG图像.     

一种针对彩色JPEG图像的安全隐写算法

为进一步增强载密彩色JPEG图像的安全性,提出一种针对彩色JPEG图像的安全隐写算法.算法把原始彩色JPEG图像的每个8×8分块进行DCT变换后,对各块中具有相同频率的R,G,B各分量的AC系数用密钥控制生成一个近似服从高斯分布的整数序列进行整除取余,将余数的LSB构成序列brbgbb,对brbgbb采用矩阵编码嵌入秘密信息.实验结果表明:与同类算法相比,该方法对彩色JPEG图像可提供较大的嵌入容量,载密彩色JPEG图像具有较好的视觉质量,且能够抵几种常见的隐写分析方法.     

基于边信息估计的JPEG图像隐写方法

基于JPEG图像的隐写方法通常利用原始图像的边信息来提高隐写安全性.然而现有的JPEG图像隐写方法在使用边信息时需要提前获取未压缩的原始图像,当原始图像不可获得时,往往不能把边信息用于设计隐写方法.文中提出了一种在不具有未压缩的原始图像的情况下,通过估计图像的边信息来提高JPEG图像隐写安全性的方法.首先,使用卷积神经网络对JPEG载体图像进行恢复,得到估计的原始图像;其次,通过得到的估计图像计算取整误差;然后利用取整误差来控制嵌入过程中离散余弦变换(DCT)系数的修改方向;最后结合DCT系数的失真代价和STC编码来实现隐写嵌入.文中提出的边信息估计方法能够应用于现有的JPEG图像自适应隐写方法,如JC-UED和J-UNIWARD.实验结果表明,该方法能较好地恢复图像的边信息,并能显著提高现有JPEG图像自适应隐写方法的安全性.     

HCGAN:一种基于GAN的高容量信息隐藏算法

针对现有信息隐藏算法存在隐写容量低、信息提取困难以及安全性差等问题,本文提出了一种基于生成对抗网络的高容量信息隐藏算法（High Capacity Information Hiding Algorithm Based on GAN,HCGAN）.在秘密信息嵌入方面,使用基于Im-Residual结构的编码器将秘密信息嵌入载体图像中,避免了秘密信息嵌入时由卷积层提取特征导致的信息损失.在秘密信息提取方面,使用基于稠密结构的解码器从含秘图像中提取出秘密信息,利用特征复用来增加秘密信息的提取率.在抗隐写分析方面,利用基于隐写分析的鉴别器与基于Im-Residual结构的编码器进行对抗训练,以提高含秘图像的抗隐写分析能力.实验表明,经过对抗训练后,HCGAN在2 bpp嵌入率下比WOW和S-UNIWARD在0.4 bpp嵌入率下具有更低的隐写分析检测率.     

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

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