基于分形和骑士巡游的图像压缩加密算法研究

将分形编码和骑士巡游相结合,提出一种基于分形和骑士巡游的图像压缩加密算法。首先用骑士巡游产生的路径作为密钥,路径用矩阵表示,矩阵中的每一元素与图像分形编码中的每个值域块相对应。然后按照骑士巡游的路径,从某个元素开始依照某个步长的顺序进行分形编码,为保证图像质量可以进行四叉树分裂。解码是其逆过程。用MATLAB对该算法进行仿真实验,测试了置乱度、密钥敏感性,在保证一定解码图像质量的情况下,压缩比优于JPEG。     

一种快速分形图像编码算法

目前,分形图像编码技术最主要的缺点仍然是编码时间太长.因此,如何提高分形图像编码速度成为当前分形图像编码技术的研究热点.本文从分形图像编码通用公式推导出一个不等式,利用此不等式,可以预先排除大量不可能与值域块匹配的定义域块,从而减少值域块与定义域块的匹配计算,以此达到缩短编码时间的目的.实验结果表明,在解码图像质量基本不变情况下,本文的方法所使用的编码时间比Fisher方案所需的编码时间减少了很多.     

基于FGSE的快速分形图像编码算法及其多描述编码方案

本文在基于分形图像编码的多描述编码方案（MDFIC）的基础上，做了两处改进：一是引入提出的基于FGSE的快速分形图像编码算法，以提高编码速度；二是利用相邻值域块均值间的相关性，以减少比特率。实验结果表明，本方案与MDFIC相比，可以在保持解码图像质量几乎不变的情况下，提高编码速度和减少比特率，并具有较高的鲁棒性。     

基于子域对角和的快速分形图像编码算法

为了改进分形图像压缩编码过程耗时过长而影响实用的问题,新定义了子域对角和来描述图像块的特征.算法把码本按照子域对角和特征的大小排序,对每个待编码的Range块,仅在赋序码本中找到与Range块的子域对角和的数值最接近的Domain块,并在此Domain块的邻域内搜索最佳匹配块.实验结果表明,在保证解码图像质量的前提下,该算法较快地提高了编码速度.     

四线和特征的快速分形图像编码

分形图像编码具有压缩比高、解码速度快、重构图像质量高等特点,但因这种算法在编码时定义域的搜索量十分巨大,导致其计算复杂度高、编码时间过长,阻碍了它的实用性和普遍应用.为解决此问题,文中提出一种基于四线和特征值编码算法,该算法根据匹配均方根误差与四线和特征间的关系,将全局搜索转化为局部搜索(近邻搜索),限定搜索空间,减少定义域块的搜索,从而提高编码速度.仿真实验结果表明:该算法解码图像质量在客观上优于1 -范数特征算法;与基本分形编码算法相比,基于四线和特征算法在主观上不改变重构图像质量,但在编码速度上却得到极大提高.     

一种改进的分形图像压缩算法

为了缩短分形编码时间,通过对图像定义域块和值域块的统计特性分析,提出了改进的分形压缩算法。设计最优匹配定义域块自适应搜索方法,缩短搜索范围;用值域块均值代替灰度偏移量,减少计算量。实验证明,运用这种改进的分形图像压缩算法进行图像压缩,在保持较高的解压图像质量的情况下,大幅缩短图像压缩编码时间。     

一种改进的分形图像压缩算法

为了提高分形图像压缩编码的速度,针对在基本分形图像压缩算法中值域块编码匹配搜索时需要对变换后的定义域块一一对应,导致编码时间较长的缺点,提出了一种基于菱形搜索算法的分形图像压缩编码新算法.菱形搜索算法是一种运动估计的快速搜索算法,主要过程是在所有的候选块中搜索当前块的最优匹配块.通过运用菱形搜索算法中的大小菱形模板进行匹配搜索,实验证明文中算法在提高编码速度和降低编码复杂度是有效的.     

基于对称性与方差的快速分形人脸图像压缩

针对人脸具有对称性特点，提出了基于对称性与方差的快速分形人脸图像压缩算法。在编码时，对某值域块，将定义域块限定在与其对称的候选区内，如在其中未找到匹配定义域块，则再扩大候选区范围。对基于方差方法与本文算法在时间复杂性上的分析表明，即使在最坏情况下，利用本算法所需编码时间也仅为基于方差方法的1／2。通过在ORL和YALE人脸库中的实验表明，利用本文算法，在基本保持恢复图像质量的同时，平均编码时间仅为基于方差方法的1／3。实验还讨论了候选区、阈值与击中值域块个数、编码时间和峰值信噪比（PSNR）间的关系。     

多级分类分形块编码

文中提出了多级分类分形块编码，在编码时，利用多级四叉树剖分方法，将图像块剖分成不同大小的平坦子块和非平坦子块，分别采用均值编码和分形编码。在对值域块进行分形编码时，为缩短分形编码时间，将值域块和定义域块分成７２类，并分别在同类进行仿射匹配，实验结果显示，多级分类分形块编码极大地缩短了编码时间，同时也提高了分形编码的压缩比。     

基于矢量量化的层次分形编码方法

文中提出了一种新的分形图像压缩方法,该方法将矢量量化的概念应用于分形块编码中,对图像的平缓区进行矢量量化的线性组合编码,对图像的丰富细节区用分形编码,并且在分形编码时,采取了层次处理。实验表明,与基本的分形块编码方法相比,本文提出的矢量量化层次分形编码方法在保证一定的重建图像质量下,使图像的压缩比有了明显的提高,并且大大提高了编码和解码速度。     

Technology innovation and process integrations for sub-100nm gate patterning

This paper presents a brief overview of the Applied Centura(R)DPS(R)system,configured with silicon etch DPS Ⅱ chamber, with emphasis on discussing tuning capability for CD uniformity control. It also presents the studies of etch process chemistry and film integration impact for an overall successful gate patterning development. Discussions will focus on resolutions to key issues, such as CD uniformity, line-edge roughness, and multilayer film etching integration.     

Complete approach to automatic identification and sub-pixel center location for ellipse feature

To meet the need of automatic image features extraction with high precision in visual inspection, a complete approach to automatic identification and sub-pixel center location for similar-ellipse feature is proposed. In the method, the feature area is identified automatically based on the edge attribute, and the sub-pixel center location is accomplished with the leastsquare algorithm. It shows that the method is valid, practical, and has high precision by experiment. Meanwhile this method can meet the need of instrumentation of visual inspection because of easy realization and without man-machine interaction.     

White organic light-emitting devices based on fac tris（2- phenylpyridine） iridium sensitized 5,6,11,12-tetraphenylnap -hthacene

We have fabricated the white organic light-emitting devices （WOLEDs） based on 4,4＇ -bis（2,2 -diphenyl vinyl）-1,1＇ - biphenyl （DPVBi） and phosphorescence sensitized 5,6,11,12,-tetraphenylnaphthacene （rubrene）. The device structure is ITO/2T-NATA （20 nm）/NPBX （20 nm）/CBP： x%Ir（ppy）3：0.5% rubrene （8 nm）/NPBX （5 nm）/DPVBi （30 nm）/Alq（30 nm）/LiF（0.5 nm）/A1. In the devices, DPVBi acts as a blue light-emitting layer, the rubrene is sensitized by a phosphorescent material, fac tris （2-phenylpyridine） iridium [Ir（ppy）3], acts as a yellow light-emitting layer, and N,N＇ -bis- （1-naphthyl）- N,N＇ -diphenyl -1, 1＇ -biphenyl-4,4＇ -diamine （NPBX） acts as a hole transporting and exciton blocker layer, respectively. When the concentration of Ir （PPY）3 is 6wt%, the maximum luminance is 24960 cd/m^2 at an applied voltage of 15 V, and the maximum luminous efficiency is 5.17 cd/A at an applied voltage of 8 V.     

小角度扩展相关性近似算法分析

本论文提出一种在多天线MIMO信道相关性建模中小角度扩展近似理论算法,并应用于分析MIMO系统性能。分析中分别对三种不同角能量分布情况下的空间相关性研发快速近似计算法,并同时提出双模(Bi-Modal)角能量分布情况下的近似运算。通过分析这些新方法的近似效率,可以得到计算简单、复杂度低、而且符合实际的MIMO相关信道矩阵,对系统级的快速高效计算法的研究和系统级的评估以及误差分析具有重要的意义。     

A Versatile Mixed-Signal Pin Approach for Cost-Effective Test of Automotive ICs

Integrated circuits (ICs) intended for increasingly sophisticated automotive applications bring unique test demands. Advanced ICs for applications such as highly integrated automatic braking system (ABS) and airbag controllers combine high voltage digital channels, significant VI demands and precise timing capability. Along with continued missioncritical reliability concerns, the trend toward higher voltage operation and increased device integration requires specialized test capabilities able to extend across the wide operating ranges found in automotive applications. Among these capabilities, automotive test requirements increasingly dictate a need for a cost-effective versatile mixed-signal pin electronics with very high data rates reaching up to 50MHz with a voltage swing of-2 V to +28 V.     

Optical vibration and deviation measurement of rotating machine parts

It is of interest to get appropriate information about the dynamic behaviour of rotating machinery parts in service. This paper presents an approach of optical vibration and deviation measurement of such parts. Essential of this method is an image derotator combined with a high speed camera or a laser doppler vibrometer （LDV）.     

社长序言（英文）

正Happy New Year!As we step into a new year,we take a look back at the key feature topics covered in China Communications over the past 12 months and set out our expecta-     

Call for Papers

正Introduction Jointly sponsored by the China Institute of Communications(CIC)and the IEEE Communications Society(IEEE ComSoc)since the year 2013,China Communications,currently,is aiming to gradually realise the transition from journal to magazine content and style.     

INTEGRATION OF OPTICAL AND WIRELESS NETWORKS

正For a long time,optical and wireless systems/net-works are developed in separate communities witha few attempts for in-depth convergence.In fact,it prom-ises many advantages to combine the optical and wire-less technologies in the levels of systems and networks.Recently,both academia and industry have made manyefforts to enter a new phase of development to take op-tical and wireless systems as fully integrated networks.To provide high bandwidth and reliable service for bothfixed and mobile users,a well-designed network must     

Call for Papers—Feature Topic,Vol.12,No.3,2015

正Smart Grid Communications The electric power industry is undergoing profound changes as the industry aims to capture the promise of a smart grid for a sustainable energy future.Enabled by the advanced sensing devices such as Phasor Measurement Units(PMUs),increasingly powerful