一种基于人眼视觉特性的零树小波编码方法

嵌入式零树小波编码被认为是目前国际上最先进的图像编码方法之一,仍然有不足之处,其中之一是该算法在编"孤立零"码时会造成比特位冗余,因此在分析了零树编码不足的基础上,提出了基于人眼视觉特性的零树小波编码方法.该方法首先对小波系数进行基于人眼视觉特性的标量量化,然后再进行零树编码.实验结果表明该方法在保证恢复图像具有良好的视觉效果的前提下,进一步提高了压缩比.     

省略零平面的彩色视频编码

为提高彩色视频的压缩比,在定义四维矩阵零平面的基础上,提出了一种"省略零平面"的编码方法.彩色视频在经过四维矩阵离散余弦变换(4DMDCT:Four-dimensional Matrix Discrete Cosine Ttansform)和四维矩阵量化后,量化系数中存在着大量的零系数.在对这些系数进行游程编码时,过多的零系数使得互不相同的游程数目多而分散,从而降低了熵编码的效率."省略零平面"编码使得大多数描述零系数的游程变短,而且变得较为集中.而对于每个子矩阵中省略的零平面信息,用额外的几个比特来表示,并对其进行DPCM(D卅erential Pulse Code Modulation)编码.实验结果表明,在保证较好视觉效果的前提下,该方法的压缩比一般可达到200倍以上.     

一种基于人眼视觉特性的零树小波编码方法

嵌入式零树小波编码被认为是目前国际上最先进的图像编码方法之一，仍然有不足之处，其中之一是该算法在编“孤立零”码时会造成比特位冗余，因此在分析了零树编码不足的基础上，提出了基于人眼视觉特性的零树小波编码方法。该方法首先对小波系数进行基于人眼视觉特性的标量量化，然后再进行零树编码。实验结果表明该方法在保证恢复图像具有良好的视觉效果的前提下，进一步提高了压缩比。     

MPEG-4码率控制方案的改进研究

针对低码率、低时延视频通信中MPEG-4 Q2码率控制方案导致的图像质量波动问题,利用拉格朗日乘子法,提出了一个率失真优化的目标比特估计算法(LAG-BA),根据前一帧图像的编码信息和虚拟缓存器状态预测当前帧的目标比特数.LAG-BA不但降低了连续图像质量变化的幅度,而且保证了算法与输入图像内容的自适应性.针对LAG-BA的误差累积效应,根据最小二乘支持向量机的原理,进一步提出了一个考虑到多个相关图像编码信息的目标比特估计算法(LSSVM-BA),并用LAG-BA和LSSVM-BA取代MPEG-4 Q2方案中的比特分配算法设计了两个改进的MPEG-4 Q2方案.实验结果表明,与原始的MPEG-4 Q2方案相比,两种改进的MPEG-4 Q2方案不但取得了更加平稳的图像质量,而且分别使编码的峰值信噪比提高了0.12 dB和0.44 dB.     

一种适于遥感图像的图像压缩算法

提出一种适于遥感图像的压缩算法,将小波分解后的系数按照零树的方法排列为树状集合,再将树状集合排列为集合树块,为提高数据压缩效率,将集合树块划分成若干比特平面,利用分辨率之间的相似性和相邻系数之间的相关性进行比特平面编码;树块之间独立进行编码,以提高系统抗误码能力．对算法进行了系统仿真,结果表明,本算法压缩效率优于SPIHT压缩算法,且编码算法更简单,系统硬件易实现．     

基于包头信息的MPEG-2视频压缩算法优化

MPEG-2视频编码标准采用基于运动估计和补偿的自适应DCT变换.其头信息,包括运动矢量和编码模式在内,在以低码率编码视频时常常占用太大的比特率,以致降低视频质量.本文提出的基于包头信息的MPEG-2视频压缩优化算法降低了MPEG-2视频编码中的头信息和运动矢量的比特数占有率,提高了对DCT系数的比特数分配,保证了低码率下的视频图像质量,同时也很好地保持了与现有MPEG-2解码器的兼容性.     

一种用于JPEG2000的高效位平面编码电路

研究了JPEG2000编码芯片的核心模块——位平面编码电路.通过分析EBCOT编码原理、现有算法及硬件实现中存在的问题,提出了一种基于双上文窗口并行的EBCOT系数位建模方法的新型位平面编码电路架构,可以实时生成编码时所需的状态信息,在提高整体编码速度的同时节省存储资源.仿真结果表明,对于一个512×512的YUV图像,采用码块大小为64×64的方式编码,1个时钟周期可以处理4个样本,并且减少约16kbit的存储器需求.     

基于医学图像ROI形状估计的改进SPIHT算法

为提高医学图像的传输质量和编码效率,提出了一种新的位平面提升方法和基于感兴趣区域（ROI）形状估计的改进分层树集合分割排序（SPIHT）算法．位平面提升时,采用交错提升方法,在不需传输掩模的情况下实现感兴趣区域与背景的相对质量可调;对提升后的位平面,通过传输ROI外接规则形状的几何参数,根据估计的掩模信息超前判定零树,节省图像比特数．实验结果表明,在相同的截断码流下,相比SPIHT算法,改进的算法无论是ROI还是整幅图像都有更好的图像质量,且码率越低效果越明显．     

MPEG-4形状编码研究

MPEG-4标准实现了从基于像素的编码向基于对象和内容的编码的转变．标准中引入了视频对象平面（VOP）的概念，每个VOP即是一个语义意义上的对象或感兴趣的对象内容，VOP具有形状、纹理和运动三种属性，其中形状编码是MPEG-4与传统视频编码标准的最大区别．通过对MPEG-4的研究探讨，提出一种基于边缘轮廓的形状编码方法：改进的Freeman链码法，将它与传统的链码方法从码长、链码长度、是否独立于旋转操作、链码总位数四个方面进行了比较，给出比较分析结果．     

一种高效的JPEG2000位平面编码器设计

针对JPEG2000 芯片实现时的硬件复杂性和编码效率低的问题,通过分析编码所需状态变量的产生机制,得到了一种最高有效位(MSB)检测电路,它能使状态变量实时产生.同时,在 3 个通道编码时引入列快速扫描电路,它在清除通道编码中设计了游程编码和0编码的流水实现电路,最后得到了位平面编码器 0冗余时钟设计.将此方法用于实现三通道并行的位平面编码器时,相对于单通道的跳点跳列,其运算速度可提高2倍,逻辑电路节约50%,而对于64×64像素的码块,存储器节约20 kb.     

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