基于小波变换的JPEG编码方法的探讨

小波变换是近几年在图象处理领域中新兴的一种变换方法，以性能优越而日益受到人们注意。本文通过实验方法探讨了小波变换与现有ＪＰＥＧ编码体系相结合的可能性，并与采用了其它编码方法的小波变换编码和ＪＰＥＧ编码进行了比较，对三种编码方法在图象压缩 效果及性能进行了评估。     

基于小波系数结构特征的高倍率图像压缩方法

针对图像小波系数在各子带内显著性分布的聚簇特征,提出了在SPIHT算法的输出环节引入游程编码,对游程编码算法的性能进行分析后,基于算法的最优编码条件,对SPIHT算法中LIS的初始化操作进行了优化,提出了一种改进的多分辨系数扫描方法,使得显著系数在LISLIP中的一维分布更趋集中,从而使游程编码获得了更高的压缩效率．实验结果表明,与SPIHT相比,在几乎不影响压缩时间的同时,在高倍率压缩应用中提高了图像的重建质量近1dB．     

用于图像压缩的小波系数的上下文模型

结合GlicBawls编码方法的线性预测思想和CALIC编码方法通过量化减少上下文个数的思想，提出了一种新的用于图像压缩的小波系数的上下文模型。它通过量化当前系数的线性预测值形成上下文，进行自适应的算术编码。实验结果表明，利用这种模型获得的无损压缩比高于无损的SPIHT和用于JPEG2000的无损的EBCOT。另外，这种模型充分利用了小波变换的多分辨率性质，能以渐近分辨率(progressive resolution)方式压缩图片，并且它获得的原图片的各个比例尺(scale)的小图片的压缩比也高于EBCOT。     

语音DCT变换的一种小波编码方法

语音信号离散余弦变换的小波变换编码方法是根据DCT变换和小波变换特点，并结合语音信号的特征而提出的一种高效简便的语音编码方法，在编码中，对不同层次小波系数分配不同的量化位，可灵活、方便地控制重构话音的质量，以汉语语音音节为例的实验表明，在16kbps的编码数据率时，重构(或再生)的话音质量与原始话音质量基本相同。     

图像压缩编码技术及其国际标准

作者在本文论述了现存的图像压缩编码技术，并将其方法分为两大类，即经典压缩编码方法和现代压缩编码方法，分析其优缺点，并着重论述现代编码方法和图像压缩编码的国际标准。     

基于方向剖分的小波域分形图象压缩

该文提出一种新的分形和小波混合编码方法－基于方向剖分的小波域分形图象压缩方法：在将图象分解到小波域后，对各子图象，根据其所占能量的大小和所代表的方向纹理信息，采用不同大小、形状与类别的定义域块和值域块进行分形编码，经实验证明，这种基于方向剖分的小波域分形编码方法，在保证一定的还原图象质量的前提下，可以大大地提高了分形编码的速度，如果结合多层小波分解的分形压缩编码的预测法和零树法，还能进一步提高压缩率，从而使分形图象编码向实时应用迈进了一步。     

对“码率压缩技术”的分析与评价

本文介绍了数字码率压缩的分类，码率压缩的基本原理，对预测编码、变换编码、矢量量化、子频带编码、霍夫曼编码和运动补偿做了一些分析。内容以介绍基本原理为主，并对不同的编码方法做了简要的评价     

分形压缩编码算法的改进

在分析总结分形理论的基础上，提出了一种将小波变换压缩编码与迭代函数系统（IFS）分形编码相结合的图象压缩方法，研究结果表明，与一般的分形图象编码方法相比，运算时间下降而压缩比提高。     

基于小波变换的图像压缩编码方法研究

介绍了小波变换的基本理论以及基于小波变换的图像压缩编码与解码恢复过程。为了研究基于小波变换的图像压缩编码方法的优越性,通过实验与传统的离散余弦变换编码方法进行了性能的对比分析,实验结果表明：由于小波变换具有时间-频率局部化特性和多分辨率特性等优点,其能够更加有效地应用于图像数据压缩,可以达到更高的压缩效率,而且理论上可以获得任意压缩比的压缩图像。     

采用视觉加权自适应阈值量化的彩色图像小波编码方法

提出了一种基于视觉特性的彩色图像小波变换编码方法.该方法是以一种简单的灰度图像小波编码方法为基础,首先通过小波变换将图像进行多分辨率分解;然后对彩色分量的高频子带数据进行适当的抛弃;对小波图像的高频数据采取自适应阈值量化方法克服恢复图像中的分量独立点噪声污染现象;最后根据小波系数的码字分布特征,采用行程编码结合Huffman编码.该方法可保证重建图像的主观视觉效果良好,而且具有较高的压缩倍率.     

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.     

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