数字方式成像技术的临床应用

目的:探讨数字方式成像技术在临床对患者进行诊断过程中的临床疗效。方法:收集我院1年间进行胸部影像学检查的患者100例,随机分为观察组和对照组,各50例。对照组患者使用常规的X线的检查方法对患者进行诊断,观察组患者使用数字X线摄影的方法对患者进行诊断,比较两种方法对患者进行检查完成后的图像质量以及对患者进行诊断完成后的准确程度。结果:两组患者均有一定的诊断效果,但观察组患者的图片清晰程度以及对比度均明显优于对照组患者,在质量分级方面,观察组患者的图像质量分级明显优于对照组患者,同时观察组患者的检出率90%明显优于对照组患者的检出率60%,所有差异均为显著性差异(P0.05),有统计学意义。结论:在临床对于患者进行诊断的过程中,通过使用数字方式成像技术能够显著的提升对患者进行诊断过程中的漏诊率,同时数字成像技术能够显著的克服一些非直接转换技术探测器在实际使用过程中由于光线散射造成的图片清晰度不高的情况,同时在实际的对患者进行诊断的过程中的环节相对较为简单,能够显著的降低影像信息的丢失情况,提升在对患者进行诊断过程中的诊断效果,在临床上值得推广应用。     

数字放射成像技术的临床应用

目的：探讨数字放射成像技术的临床应用价值。方法：收集2013年1月至2014年1月期间,我院接受胸部影像学检查的患者115例,分别应用常规X线检查以及数字X射线DR摄影,比较两种检查技术的图像质量。结果：115例患者经胸部数字化X射线检查显示,图像的清晰度以及对比度均较好,对于细微结构的图像显示效果也较为清晰。数字化X射线图像质量分级显著优于常规X射线检查图像（P〈0.05）。结论：数字化X射线DR摄影能够有效克服非直接转换技术探测器因闪烁体或者增感屏内光纤散射所致图像模糊等情况,提高图像清晰度,且数字化过程环节相对减少,可降低影像信息丢失,提高空间分辨率和诊断效能,值得推广应用。     

数字加网图像的质量评价研究

介绍了两类典型的数字半色调算法以及主观评价和客观评价两种传统的半色调图像质量评价方法.基于VisualC#编程语言建立了加网算法实验平台,并根据所得图像质量参数对各算法在再现图像的质量、运行时间等方面进行了比较和分析.     

成像降质效应对前视红外图像质量的影响分析

前视红外图像质量对于目标检测与跟踪算法能否准确定位目标具有十分重要的作用。目前对自动目标识别领域前视红外图像质量的研究大都与场景内容相关,而忽视了成像降质效应对图像质量的影响。本文通过分析噪声和模糊两种降质效应的成因,结合前人的模拟方法,得到了高性能前视红外成像设备获取的图像中噪声和模糊模拟的新方法。将该方法用于分析不同程度噪声和模糊对图像质量的影响,结果显示,噪声对于图像质量有害,而模糊对于图像质量并不一定有害。基于这一结论,采用去噪方法对前视红外图像进行预处理。对比实验结果表明,该方法比去模糊方法能更有效地提高匹配概率。     

错流离心分级技术的研究

通过分析分级设备中分级力场方向和介质流体流动方向 ,提出了错流分级和逆流分级的概念 ,并在详细讨论这两种不同分级形式各自特点的基础上 ,设计出一种新型的错流离心分级设备。分级实验结果表明 ,该分级设备不仅适用于微细粉末分级 ,而且能在一次分级过程中获取多个窄级别分级产品     

ERT技术图像重建算法研究

两相流参数测量中,电阻层析成像技术的图像重建算法可归为两大类,即直接法和迭代法。对常用的几种图像重建算法进行了比较性研究,结果表明:直接法速度快,但重建图像质量不理想,仅可作定性分析;迭代法总体上说重建图像质量较高,但速度较慢。当增加像素数以提高重建图像分辨率时,直接法重建图像耗时增量较小,迭代型算法中改进的Newton-Raphson算法、BFGS算法由于目标函数的Hessian矩阵维数增加,计算时间大大增加,而改进的BFGS算法因简化了Hessian矩阵及其逆矩阵的计算,时间增量则较小。     

青岛市计量所通过省局法定技术机构监督考核和实验室分级评审

日前．山东省局组织专家组对青岛市计量所实施年度法定技术机构监督考核．并对力学和长度实验室进行实验室分级评审。经过两天的考评．该所顺利通过了山东省局的法定技术机构监督评审．两个实验室也通过了分级考核。     

保持节目制作质量的一致性

本文介绍了伦敦格林威治大学的一套发明系统 ,它能使胶片电影和数字电视 ( DTV) /数字光盘 ( DVD)节目制作的质量保持一致。引言　现今摄影 (像 )师和导演被一种困难困扰——他们不知道自己的作品在不同媒体上播映时图像质量究竟如何。这使我们想起行业中的一句老话“无论你用胶片怎样制作 ,最终映现要靠这种或那种媒体”。但这句话如今却有了新意 ,且其新意正是目前我们面临的问题——各种媒体传送图像质量的能力差别太大。伦敦格林威治大学研究出一套方法 ,并开发出一套软件 ,使艺术创作人员可预先得知改变摄制方法图像质量将受何种影响。从而可保证数字电视 ( DTV)和数字光盘( DVD)技术质量一致。     

基于Surfels的实时渲染技术研究

介绍了一种用于实现复杂场景高品质实时渲染的新算法。已有的研究表明，基于传统几何图元的渲染技术必然涉及到大量的求交与消隐计算，而这正是实现实时绘制的瓶颈所在。利用OpenGL虽然可以实现实时绘制，但这是建立在Z－Buffer技术的基础上，并且将场景尽可能地简化来实现实时绘制的一种基于传统几何图元的绘制技术。这样渲染而得的图像质量很低，很难再现纹理及材质的特殊光照效果。笔者将图像与体图形学技术相结合，研究并实现了基于表面元素（Surface elements,即Surfels)的渲染技术，避免了耗时的求交计算，因此大大提高了复杂几何场景的绘制时间。又因为surfels中包含完整的材质属性和纹理信息，从而确保了在快速重绘时的图像质量。     

基于码书的雾天图像质量评价方法研究

近年来,无参考图像质量评价发展迅速,但是对雾天图像质量进行评价的无参考算法还鲜有报道。该文提出了一种基于码书的无参考雾天图像质量评价算法。目的是使该方法评价雾天图像质量的结果与人类主观感知相一致。寻找能反映雾天图像质量的特征,运用这些特征构建码书,然后用码书对训练图像进行编码得到训练图像的特征向量,最后用这些向量与训练图像的主观评分进行回归得到雾天图像质量评价模型。该方法在仿真的雾天图像库中进行了测试,结果表明：Pearson线性相关系数和Spearman等级相关系数值都在0.99以上。并与经典的无参考算法NIQE和CONIA方法进行了比较,优于这些算法,能够很好地预测人对雾天图像的主观感知。     

HDTV transmission formats and migration path

The current proposal for terrestrial broadcasting of HDTV in the United States incorporates a flexible approach toward encoding and transmission. Specifically, the format used to encode an HDTV picture will not be fixed. Instead, a variety of transmission formats will be available, unlike the current (NTSC) system. Furthermore, although a basic set of formats will exist initially, it is possible that this set can change over time, depending on the evolution of relevant technologies. This article will consider various topics related to the current and future transmission formats associated with HDTV systems in the United States. This article discusses the usefulness of allowing multiple transmission formats and describes the formats which will be immediately available for HDTV broadcasting, as agreed upon by the Grand Alliance. The relationship between source formats, transmission formats, and display formats are discussed, with reference to some of the signal processing modules required to convert between formats. Finally, the migration of HDTV to incorporate additional formats is addressed. This report describes a method of achieving this migration in a backward-compatible manner, so that the basic HDTV receivers will not become obsolete.©1994 John Wiley & Sons Inc     

A real‐time encoding and decoding system for nonlinear HDTV editor

A real‐time encoding and decoding system (REDS) for HDTV that can be used for nonlinear HDTV editing in studio has been developed. The intrapicture coding of motion JPEG is implemented and optimized in the REDS so that a high‐quality image can be recovered for the nonlinear editing. The REDS has a parallel architecture with multiple programmable digital signal processors (DSP) and reconfigurable field programmable logic devices (FPLD). The HDTV image is spatially partitioned and concurrently processed by the multiple processors. The programmable DSPs perform the discrete cosine transform and quantization to reduce the spatial redundancy of the HDTV image, whereas the FPLDs perform the variable length coding to reduce the statistical redundancy. In addition, field‐based quantization matrices are developed for HDTV images. The REDS has the programmability and the random accessibility of image frames, the two most important features for a nonlinear HDTV editing system. © 2000 John Wiley & Sons, Inc. Int J Imaging Syst Technol 11, 152–157, 2000     

Video compression for the grand alliance: A historical perspective

This article outlines the evolution of the Grand Alliance (GA) highdefinition television (HDTV) standard from its divided beginnings among several systems to its final state as the proposed standard for HDTV transmission in the United Stales today. Earlier video compression standards are briefly described, and their influence on the first four all-digital HDTV proposals is demonstrated. The salient features of each proposed video compression system are high-lighted, and the more recent MPEG-2 compression standard is introduced. MPEG-2 was adopted as the basis for video compression by the GA, a group of the former HDTV competitiors. The formation of the GA is described, and the work of its Video Compression Specialists Group on evaluating modifications to MPEG-2 is reviewed.©1994 John Wiley & Sons Inc     

Scalable optical hypercube-based interconnection network for massively parallel computing

Two important parameters of a network for massively parallel computers are scalability and modularity. Scalability has two aspects: size and time (or generation). Size scalability refers to the property that the size of the network can be increased with nominal effect on the existing configuration. Also, the increase in size is expected to result in a linear increase in performance. Time scalability implies that the communication capabilities of a network should be large enough to support the evolution of processing elements through generations. A modular network enables the construction of a large network out of many smaller ones. The lack of these two important parameters has limited the use of certain types of interconnection networks in the area of massively parallel computers. We present a new modular optical interconnection network, called an optical multimesh hypercube (OMMH), which is both size and time scalable. The OMMH combines positive features of both the hypercube (small diameter, high connectivity, symmetry, simple routing, and fault tolerance) and the torus (constant node degree and size scalability) networks. Also presented is a three-dimensional optical implementation of the OMMH network. A basic building block of the OMMH network is a hypercube module that is constructed with free-space optics to provide compact and high-density localized hypercube connections. The OMMH network is then constructed by the connection of such basic building blocks with multiwavelength optical fibers to realize torus connections. The proposed implementation methodology is intended to exploit the advantages of both space-invariant free-space and multiwavelength fiber-based optical interconnect technologies. The analysis of the proposed implementation shows that such a network is optically feasible in terms of the physical size and the optical power budget.     

论高清晰度电视和电影的图像质量

本文论述了电视分解率的基本概念和最新的高清晰度电视(HSTV)扫描格式相应的技术数据,并综述和分析了国际上对电影和HDTV在这方面的技术研究成果。基本结论是HDTV和影院放映35毫米电影的图侣质量相当。本文为电视图像质量的研究提供了渊博而精粹的基础,必将促进我国高清晰度电视的发展。     

高性能计算机的关键技术和发展趋势

介绍高性能计算机的关键技术和发展趋势。简要回顾高性能计算机的发展历史和当前形势,重点讨论大规模并行处理（MPP）所面临的挑战,包括可扩展性、友善性和可用性。介绍神威高性能计算机及其应用情况,并对如何发展我国高性能计算机提出一些初浅的看法。     

Scale-up and scale-down of membrane-based separation processes

Methods for demonstrating the scalability of purification and separation procedures depend on the technology which is being used, and therefore it is necessary to establish the physical parameters which are important to the scaling processes. This article briefly looks at these factors for direct-flow, and tangential-flow filtration technologies.     

高清晰度电视与电影图像质量的评价

高清晰度电视的出现,大大地缩短了电视图像与电影图像之间的差距。本文从制作高清晰度电视节目所需的性能参数的角度,比较了ＨＤＴＶ图像和电影图像的质量。这些性能参数包括：图像锐度、灵敏度与曝光指数,以及噪声。给出了它们之间的对比关系式,评价了ＨＤＴＶ摄像机与彩色负片的总体性能。     

Architecture and implementation of the grand alliance HDTV video encoder

A high-definition television (HDTV) video compression encoder is being constructed for use during the standardization process for United States terrestrial broadcast HDTV. The encoder generates an MPEG-2 main profile/high level compliant bitstream at compressed data rates from 10–80 million bits/second. Both interlaced and progressive image formats in image sizes up to 1080 lines × 1920 pixels per line are supported.©1994 John Wiley & Sons Inc