一种自适应双边滤波的超声图像去噪

超声图像利用不同组织和局部细节的不同回声信号强度和分布来捕捉重要的医学病变信息,但超声图像在形成过程中产生的斑点噪声使得超声图像质量较差,给以后的图像特征提取和识别、病情诊断及定量分析造成不利影响。文中在传统双边滤波既能去噪又能保持图像边缘信息性质的基础上,对传统双边滤波的灰度权系数部分进行了改进,使其局部自适应。实验结果表明了该算法的有效性。     

套管井中仪器偏心对超声回波的影响

根据声波在介质中的传播理论和换能器的声学特性，对在套管井中仪器处于不同偏心情况下的超声回波进行了模拟，研究了偏心对超声回波的影响，并进行了实验验证。数字模拟和实验结果表明：仪器偏心不仅会引起回波信号幅度的变化，而且会导致频谱的改变，当偏心大于４ｍｍ时，对回波的影响比较明显；为了保证套管井测井资料的可靠性，仪器偏心应小于３．５ｍｍ。     

套管井中仪器偏心对超声回波的影响

根据声波在介质中的传播理论和换能器的声学特性，对在套管井中仪器处于不同偏心情况下的超声回波进行了模拟，研究了偏心对超声回波的影响，并进行了实验验证．数字模拟和实验结果表明：仪器偏心不仅会引起回波信号幅度的变化，而且会导致频谱的改变．当偏心大于４ｍｍ时，对回波的影响比较明显；为了保证套管井测井资料的可靠性，仪器偏心应小于３．５ｍｍ．     

基于二维高斯曲面拟合的图像灰度补偿算法

研究了基于CCD的带钢表面缺陷检测系统图像采集中出现的灰度失真问题,提出了在不改变系统硬件配置的基础上,根据主导退化因素采用二维高斯曲面为基本退化模型,同时兼顾其他没有明确数学模型的图像退化因素,根据图像灰度分布统计特性估计二维高斯曲面各参数以实现图像灰度补偿的软解决方法,实验结果表明,该算法有效地提高了图像质量,可以满足系统实时性及后续识别的要求．     

基于掩盖效应空间相似性的图像质量评价方法研究

掩盖效应是HVS模型的一部分,基于掩盖效应的图像质量评价方法只考虑了标准图像的影响,忽略了误差图像本身的影响。依据掩盖模型和空间向量分解,文章提出了一种新的图像质量评价方法。该方法将误差图像分解得到对比度无关分量,与掩盖阈值比较,剔除低于掩盖阈值的部分。通过实验表明,该方法简单易行,从视觉感知和结构化2个方面对图像质量进行评测,比传统客观方法更贴近人眼主观感受。     

超声破解污泥的实验研究

在超声破解污泥实验中,研究反应器形状和换能器位置对污泥滤液的COD、NH3-N、TP的影响.实验结果与理论分析符合较好,从而说明反应器形状和换能器位置是影响污泥破解效果的重要因素,也说明超声是一种有效的破解污泥的方法,进而对超声处理污泥的规律进行研究.     

基于高分辨超声成像平台的无创血管力学及动力学特性分析研究报告

该研究提出了一种可同时无创测量颈动脉壁力学特性、血管壁剪切率的变化以及脉搏波在局部短距离血管片段上传播速度的超声定量成像和评价方法。为了提高超声成像的分辨性能,同时补偿由于入射角度不同造成的血管侧壁灰度的非均匀性,在应变估计之前首先对超声图像进行了高分辨图像重建与灰度非均匀性的校正。在相同的成像平面下,保持声束与血流的夹角呈90°,血流速度与剪切率沿管径的分布可由沿血管直径方向采集的若干个位置处的横向多普勒信号重建得到。最后,使用超快速平面波成像技术结合射频互相关算法可获取沿38 mm血管片段的膨胀波群及脉搏波传播速度。目前临床动脉粥样硬化病人的在体实验已证实了该方法在斑块早期诊断中的有效性,因此该研究提出的超声定量成像和评价方法有望成为一种颈动脉粥样硬化斑块普查的新手段。     

基于多尺度边缘的血管内超声图像增强算法

血管内超声图像同时具有低对比度和低信噪比的特征,传统的图像增强算法会明显放大噪声.为此,提出一种基于边缘表示的算法来增强血管内超声图像的对比度,采用平滑函数的导数作为小波函数对图像进行二进小波分解,使用小波系数在各尺度间的局部极大值来刻画图像的多尺度边缘,通过拉伸小波系数极大值再重构图像来增强灰度图像的对比度.实验结果表明,本文提出的增强算法在有效增强图像对比度的同时避免了放大噪声,并且可以通过调节不同尺度的拉伸因子来获得不同的增强效果,同时提高了运算速度.     

基于掩盖效应图像质量评价方法的研究

文章针对原始图像对噪声图像的影响,依据人眼视觉掩盖模型,结合实验得出的掩盖阈值以及对CSF曲线的分析,给出了一种基于掩盖效应的图像质量评价方法。实验通过叠加相同噪声,考察了不同频率的原始图像对噪声的掩盖能力。结果表明,该方法简单易操作,正确反映了原始图像平均背景频率变化,对掩盖效应以及图像质量的影响,比传统客观方法更加符合人眼主观感受。     

一种基于直方图变换的光学遥感影像自动增强方法

对比度、清晰度等视觉效果是影响图像质量的重要因素。针对光学遥感图像对比度和清晰度改善问题,提出了一种新的视觉效果自动增强模型。首先对输入图像的直方图采用非线性变换,在保持灰度级有效分布的前提下充分压缩灰度分布范围,从而获得优化的变换系数,然后再利用线性拉伸算法将图像灰度扩展至整个灰度域。实验和对比结果表明,所提出的增强模型在很小的信息熵损失条件下能较大幅度地提高图像的对比度和清晰度,获得比目前主要算法更好的增强结果且效果稳定,可适用于全色图像和彩色图像视觉效果的全自动化增强处理。     

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