基于EM算法相关噪声模型估计的Wyner-Ziv分级视频编码

文中提出了一种基于EM算法的相关噪声模型估计的Wyner-Ziv分级视频编码方法,基本层用复杂度相对较低的DISCOVER相关噪声模型参数估计方法,保证了基本的图像质量;增强层利用EM算法在线学习,建立相关噪声模型.实验结果表明,文中提出的噪声模型估计算法与DISCOVER的噪声模型相比,在相关噪声分布有拖尾现象时,能使编码器的率失真性能明显提高.     

基于VTS的稳健语音识别

为了进一步提高矢量Taylor级数(VTS)算法的模型补偿精度以及在噪声环境下的识别性能,提出将无监督聚类与VTS算法相结合。无监督聚类算法利用噪声模型之间的Kullback-Leibler距离将含噪语音段划分为若干个子段。然后针对各个子段分别进行一阶Taylor级数展开,并在此基础上逐段估计噪声参数和补偿声学模型。该算法结合一个中文数字串识别系统进行实验,在Babble噪声和Gauss白噪声环境下该算法的误识率相对传统的VTS算法分别下降了27.7%和17.8%。证明这种结合无监督聚类的分段VTS算法能够更加有效地将语音和噪声在倒谱域上的非线性混合模型用一阶线性模型来近似。     

一种基于巴克域噪声估计的语音增强算法

为了在保证语音增强算法性能的同时,降低算法复杂度,提出了一种巴克域最小统计量控制递归平均噪声估计算法.将带噪信号在巴克域进行分解并进行最小统计量分析,基于此最小统计量控制噪声的递归平均估计.算法基于听觉模型,充分利用巴克带内频带间的相关性,具有较好的噪声跟踪估计性能.该算法复杂度低,适用于常见语音增强方法.仿真结果表明,基于该噪声估计的语音增强可以有效地抑制噪声,增强后语音失真较小,在低信噪比条件下能够有效改善语音编码合成后的语音质量.     

单向分布式视频编码中迭代相关性噪声细化方法

针对单向分布式视频编码(UDVC),文中提出了迭代相关性噪声细化方法.在迭代解码过程中,利用上次解码的重构系数对相关性噪声进行细化,提高相关性噪声的估计精度,并且在细化过程中根据系数的解码可靠性对残差进行分类加权细化来避免错误解码系数对细化的误导.实验结果表明,经过相关性噪声细化后,重构帧中由于码率欠估计导致的质量退化问题得到了明显的改善,不同视频序列重构WZ帧的平均峰值信噪比(PSNR)可以提高0.32～0.13 dB;和未细化的单向DVC相比,文中基于相关性噪声细化的单向DVC系统的整体平均PSNR也提高了约0.21 dB.     

空间相关信道下空时分组码的子空间修正解码

针对空时分组码子空间盲解码算法在空间相关信道下性能下降的问题，提出了一种修正解码算法．在分析空间相关性破坏信号子空间和统计噪声子空间正交性的基础上，利用接收端已知的信道相关矩阵，修正接收端用于搜索的码字矩阵集合，使相关信道下分解得到的统计噪声子空间正交于修正的发送信号子空间，提高了解码性能．与传统解码的算法不同，该算法无需在发送端进行信道相关矩阵的估计和预编码，降低了发送端的编码复杂度．Monte-Carlo仿真实验表明，空间强相关信道下空时分组码子空间盲解码性能下降比较剧烈，采用新算法修正后的解码性能明显改善，在误比特率为10^-2、相关系数为0．8时，修正性能提高约2dB．     

基于MDT特征补偿的噪声鲁棒语音识别算法

针对噪声环境下语音识别系统性能下降的问题,提出一种基于语音时频相关性的Mel特征矢量聚类补偿算法。该算法首先实现掩码估计,利用纯净语音信号时域和频域的相关性,实现了时频块的有效划分和基于时频块的语音特征聚类。在此基础上,对带噪语音的Mel语谱进行特征补偿。采用HTK工具和TIDIGITS数据库加入不同类别噪声的语音测试结果表明:该算法在不同信噪比条件下,获得了较基于频域相关性聚类特征补偿算法更好的性能。     

分布式视频编码中相关噪声模型优化算法

在分布式视频编码中,准确的相关噪声模型(correlaiton noise model,CNM)是影响系统的关键因素。通过研究变换域中WZ帧与相应边信息的残差系数的分布关系,发现实际的残差分布与拉普拉斯分布模型存在一定的偏差。通过分析相关噪声模型的特性,提出相关改进算法。即根据残差系数的大小与实际概率置信度的关系,采用不同的分布参数,使得改进后的拉普拉分布模型更接近实际的残差分布。实验结果表明,该优化算法有效提高了系统的率失真性能,不仅降低了系统解码的码率,同时提升了最小均方误差(minimun mean square error,MMSE)重建的质量。     

利用改进的超像素分割和噪声估计的图像拼接篡改定位方法

通过检测图像局部噪声水平的不一致性,提出一种图像拼接篡改区域的定位方法.首先,用改进的简单线性迭代聚类(SLIC)超像素分割算法将待检测图像分割成具有相似特征的像素块;然后,采用基于主成分分析的噪声水平估计方法计算每个图像块的局部噪声水平;最后,利用3种聚类算法对估算的噪声水平进行聚类,根据聚类结果定位出被篡改的区域.实验结果表明:文中方法不仅能有效定位被篡改的区域,而且能保留检测区域更多的边缘信息.     

基于子带信噪比估计和软判决的鲁棒双耳声源定位算法

为了提高噪声和混响环境下的双耳声源定位算法性能,提出了一种基于子带信噪比估计和软判决的双耳互功率谱和耳间时间差估计算法.首先根据每帧中每个子带双耳声信号的自相关矩阵估计子带信噪比;其次,将子带信噪比映射为软判决值,并对双耳互功率谱进行加权;最后利用加权后的互功率谱估计耳间时间差,从而判断目标声源方位.仿真测试和实际环境测试均表明:与基于互相关函数、过零率的传统双耳声源定位算法相比,所提算法在噪声和混响的复杂声学环境下,显著提高了双耳声源定位性能.     

一种基于核的模糊聚类算法

结合核技术与改进的模糊c均值算法聚类准则提出一 种基于核的模糊聚类算法. 通过引入核函数, 样本点被非线性变换映射到高维特征空间进行聚类, 提高了聚类性能. 同时, 算法改进了模糊c-均值聚类模型中的概率型约束条件, 使其对噪声和野值点具有较好的鲁棒性. 在真实数据和人造数据上与常用聚类算法进行了对比实验, 结果表明该算法具有较低的时间、 空间复杂度与较好的聚类性能.     

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     

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     

Journal of Donghua University ( English Edition) Contents of Volume 31

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