感兴趣区域的非线性变换多描述编码

介绍一种基于感兴趣区域的非线性变换的多描述图像编码,能够与目前的标准图像压缩算法兼容,对图像的感兴趣区域进行更好的保护。由感兴趣区域的非线性几何变换产生冗余,对图像进行采样形成多描述编码。通过仿真实验,证实当图像在差错信道下传输而丢失描述时,该算法能够使图像感兴趣区域得到更好的恢复。     

基于小波域的图像多描述编码方法

多描述编码(MDC)是有效应对不可靠网络传输的一种新技术.本文结合二维小波域在三个方向上的相关性,提出一种基于小波域的图像多描述算法.实验证明该算法性能稳定,具有良好的重构图效果.     

基于小波域降采样的低比特率图像压缩算法

针对无线传输背景下低比特率图像压缩存在的模糊和振铃问题,提出一种基于小波域降采样和插值的高效图像压缩算法.在编码端,对图像进行小波变换,根据各高频子带特点对其进行自适应降采样处理,并采用基于小波树的小波差分缩减编码算法进行编码.在解码端,采用基于边缘方向的插值方法将解码的高频子带进行放大,对解码重建的图像采用基于强边缘的自适应滤波算法以消除振铃效应.实验结果表明,与基于空域降采样的图像压缩算法相比,该算法具有较高的图像解码质量,可有效抑制低比特率下重建图像的模糊和振铃问题.     

基于改进SPIHT的静态图像编码

本文在零树编码算法分析的基础上,针对SPIHT算法的不足,提出了一种新的零树编码算法。该算法以SPIHT为基础,改进了其零树结构及编码流程,同时引入LZC算法的标志位图思想,在保证恢复图像质量的前提下,降低了内存消耗,提高了编解码速度。仿真实验结果表明,相对于SPIHT算法而言,重构图像的峰值信噪比和直观图像质量,本文算法都表现出了优良的性能,尤其是在低比特率下表现跟明显。     

基于人眼视觉特性的低比特率图像压缩编码

为了提高编码速度和改进视觉效果,提出了一种改进的低比特率SPIHT算法。算法首先用提升小波对原始图像进行分解,再结合人眼视觉掩蔽特性,对不同区域内图像信息所对应的小波系数赋予不同视觉权值,以保证优先传输视觉上的最重要系数,最后根据系数重要性,对低频系数采用新的排列结构,并采用SPIHT编码思想完成图像压缩。实验结果表明,该算法压缩效果优于SPIHT图像压缩方案,特别在低比特率下。     

DCT子域辐射状分割的图像多描述编码算法

多描述编码（MDC）是有效提高不可靠网络中数据接收质量的一种新方法。结合JPEG编码中DCT子域系数的分布特点,在已有算法（MDBDS）的基础上提出了DCT子域辐射状分割系数的4描述图像MDC算法。该算法采用DC系数重复分配、缺失AC系数补零的方法获取较好的描述重构效果。实验证明,在相同压缩码率下,该算法的整体性能优于MDEZW、MDBDS等同类MDC算法。     

结构相似指数噪声整形算法及其在图像编码中的应用

提出一种基于双树小波变换的结构相似指数噪声整形算法（SSIM-NS） 算法并将其应用于图像编码传输中。算法是在双树小波变换后的噪声整形过程中引入结构相似指数度量（SSIM）,自适应地调整增益因子以达到最大限度聚集图像能量减少小波系数的目的,运用SPIHT编码算法对噪声整形后的小波系数进行编码并传输。实验结果表明,该算法不仅能够有效地削减小波系数个数聚集图像能量,而且在低比特率条件下重构图像具有更高的峰值信噪比（PSNR）,能够显著提高解码图像的质量。     

基于分裂系数的多描述编码

提出了一种新的多描述图像编码方案---基于分裂系数的多描述编码。通过对每一个小波系数进行按位下采样,把一个系数分裂为奇数位系数和偶数位系数。奇数位系数信息和偶数位系数保护信息构成一个描述,偶数位系数信息和奇数位系数保护信息构成另一个描述。两个描述通过不同的信道进行传输。由于每个描述都包含了奇数位系数和偶数位系数的部分或全部信息,因此,接收到一个信道的信息就可以重建出一定质量的图像。如果所有的信道传输的信息都被接收,就会得到比任何一个单独信道更好的重建图像。实验结果表明,该算法的性能优于多相变换与选择量化算法。     

一种新的低比特率图像压缩编码算法

提出一种新的低比特率图像压缩编码算法,该算法能够通过以下措施提高SPIHT算法工作效率：①结合人眼视觉掩蔽特性,对不同区域内图像信息所对应的小波系数赋予不同视觉权值,以保证优先传输视觉上的最重要系数;②结合增设预先测试及合并前两次扫描,优化了SPIHT编码方案的分集排序过程．仿真实验结果表明,所提出的图像编码方法是一种高效的图像压缩算法,其压缩效果明显优于SPIHT等编码方法(特别是低比特率下)．     

VBR流式视频的最短路径率平滑传输算法

预存储的变比特率(VBR)压缩的视频网上流式传输，提供实时视频服务．这种VBR视频呈现的突发性比特率变化特性使带宽预留和接纳控制等网络传输技术复杂化．一个行之有效的解决办法是在传输前对这种VBR视频在满足一定限制条件下进行比特率无损平滑．基于平面规划中的最短路径原理，针对存储的VBR压缩视频，文章提出了最短路径率平滑传输算法，并建立了一些相关概念．算法的结果被证明能同时满足多项优化指标：极小的峰值比特率、极大的谷值比特率及O(K)的时间复杂性，实验结果也显示算法是有效、可行的．     

有序环（域）下的程序计算与BSS机器计算

１９８９年Ｂｌｕｍ，Ｓｈｂｕ与Ｓｍａｌｅ提出了在实数域上的一个计算模型，ＢＳＳ机器计算模型主要是基于有赂图的，它很直观但没有形式化，不方便使用经典的离散计算理论中的许多成熟的工具，本文从程序设计系统出发，提出一种在任意有序与的自然的程序设计设计语言，严格定义了它的语法与语义，研究了它与     

The Expressive Power of Bijections over Weakly Arithmetized Structures

We investigate the expressive power of existential second-order formulas whose second-order quantifiers range over bijective unary functions. We show that as long as interpretations are taken over structures with a built-in linear order relation and an addition function, then quantifying over bijections is as expressive as quantifying over arbitrary unary functions. The originality of our result is that it remains true even if the first-order part of a formula contains exactly one variable (which is universally quantified). Our result immediately provides a new characterization of non-deterministic linear time on RAMs. It also permits us to derive a corollary on the Skolem normal form of first-order formulas over weakly arithmetized structures.     

An optimizing design strategy for multiple model adaptiveestimation and control

A method is proposed for designing multiple model adaptive estimators to provide combined state and parameter estimation in the presence of an uncertain parameter vector. It is assumed that the parameter varies over a continuous region and a finite number of constant gain filters are available for the estimation. The estimator elemental filters are shown by minimizing a cost functional representing the average state prediction error autocorrelation, with the average taken as the true parameter ranges over the admissible parameter set. An analogous method is proposed for designing multiple model adaptive regulators to provide stabilizing control in the presence of an uncertain parameter vector by minimizing a cost functional representing the average regulation error autocorrelation, with the average taken as the true parameter ranges over the admissible parameter set. An example is used to demonstrate the improvement in performance over previously accepted design methods     

Discovering frequent behaviors: time is an essential element of the context

One of the most popular problems in usage mining is the discovery of frequent behaviors. It relies on the extraction of frequent itemsets from usage databases. However, those databases are usually considered as a whole, and therefore, itemsets are extracted over the entire set of records. Our claim is that possible subsets, hidden within the structure of the data and containing relevant itemsets, may exist. These subsets, as well as the itemsets they contain, depend on the context. Time is an essential element of the context. The users’ intents will differ from one period to another. Behaviors over Christmas will be different from those extracted during the summer. Unfortunately, these periods might be lost because of arbitrary divisions of the data. The goal of our work is to find itemsets that are frequent over a specific period, but would not be extracted by traditional methods since their support is very low over the whole dataset. We introduce the definition of solid itemsets, which represent coherent and compact behaviors over specific periods, and we propose Sim, an algorithm for their extraction.     

Adaptive quadtree simulation of shallow flows with wet-dry fronts over complex topography

Many natural terrains have complicated surface topography. The simulation of steep-fronted flows that occur after heavy rainfall flash floods or as inundation from dyke breaches is usually based on the non-linear shallow water equations in hyperbolic conservation form. Particular challenges to numerical modellers are posed by the need to balance correctly the flux gradient and source terms in Godunov-type finite volume shock-capturing schemes and by the moving wet-dry boundary as the flood rises or falls. This paper presents a Godunov-type shallow flow solver on adaptive quadtree grids aimed at simulating flood flows as they travel over natural terrain. By choosing the stage and discharge as dependent variables in the hyperbolic non-linear shallow water equations, a new deviatoric formulation is derived that mathematically balances the flux gradient and source terms in cases where there are wet-dry fronts. The new formulation is more general in application than previous a priori approaches. Three benchmark tests are used to validate the solver, and include steady flow over a submerged hump, flow disturbances propagating over an elliptical-shaped hump, and free surface sloshing motions in a vessel with a parabolic bed. The model is also used to simulate the propagation of a flood due to a dam break over an initially dry floodplain containing three humps.     

Acquiring Both Constraint and Solution Preferences in Interactive Constraint Systems

Constraints are useful to model many real-life problems. Soft constraints are even more useful, since they allow for the use of preferences, which are very convenient in many real-life problems. In fact, most problems cannot be precisely defined by using hard constraints only.However, soft constraint solvers usually can only take as input preferences over constraints, or variables, or tuples of domain values. On the other hand, it is sometimes easier for a user to state preferences over entire solutions of the problem.In this paper, we define an interactive framework where it is possible to state preferences both over constraints and over solutions, and we propose a way to build a system with such features by pairing a soft constraint solver and a learning module, which learns preferences over constraints from preferences over solutions. We also describe a working system which fits our framework, and uses a fuzzy constraint solver and a suitable learning module to search a catalog for the best products that match the user's requirements.     

A graph model for mutual information based clustering

We propose a graph model for mutual information based clustering problem. This problem was originally formulated as a constrained optimization problem with respect to the conditional probability distribution of clusters. Based on the stationary distribution induced from the problem setting, we propose a function which measures the relevance among data objects under the problem setting. This function is utilized to capture the relation among data objects, and the entire objects are represented as an edge-weighted graph where pairs of objects are connected with edges with their relevance. We show that, in hard assignment, the clustering problem can be approximated as a combinatorial problem over the proposed graph model when data is uniformly distributed. By representing the data objects as a graph based on our graph model, various graph based algorithms can be utilized to solve the clustering problem over the graph. The proposed approach is evaluated on the text clustering problem over 20 Newsgroup and TREC datasets. The results are encouraging and indicate the effectiveness of our approach.     

An optimal path-generation algorithm for manufacturing of arbitrarily curved surfaces using uncalibrated vision

Multiple industrial manufacturing tasks require a complex path to be followed precisely over an arbitrary surface which has a geometry that is not known with precision. Examples of such tasks include welding, glue-application, cutting, plasma-spraying, etc., over commercial plates whose geometry cannot be known in advance. Such processes are in general referred to as surface manufacturing. In this work, a path is traced over the surface in an optimal fashion, using the concept of geodesic mapping. By definition, a geodesic line is the shortest line that joins two points over a surface whose algebraic representation is known. Such an optimal solution of a problem, associated with variational calculus, is the approach employed for mapping complex paths, defined in a data base, over a surface of arbitrary geometry. The straight-line segments in which a complex path can be divided are mapped onto an arbitrary surface as geodesic lines. The presented algorithm enables a user to interact with the system in a simple and efficient manner using a commercial computer pointing device. The algorithm was tested experimentally in an industrial maneuver involving arc welding, using an industrial robot and a method of vision-based, robot guidance known as camera-space manipulation. This method has the advantage of not requiring calibration of optical or mechanical components.     

An exact approach to the problem of extracting an embedded network matrix

We study the problem of detecting a maximum embedded network submatrix in a {−1,0,+1}-matrix. Our aim is to solve the problem to optimality. We introduce a 0–1 integer linear programming formulation for this problem based on its representation over a signed graph. A polyhedral study is presented and a branch-and-cut algorithm is described for finding an optimal solution to the problem. Some computational experiments are carried out over a set of instances available in the literature as well as over a set of random instances.     

An approach for supporting distributed user interface orchestration over the Web

Currently, a lot of the tasks engaged by users over the Web involve dealing with multiple Web sites. Moreover, whilst Web navigation was considered as a lonely activity in the past, a large proportion of users are nowadays engaged in collaborative activities over the Web. In this paper we argue that these two aspects of collaboration and tasks spanning over multiple Web sites call for a level of coordination that require Distributed User Interfaces (DUI). In this context, DUIs would play a major role by helping multiple users to coordinate their activities whilst working collaboratively to complete tasks at different Web sites. For that, we propose in this paper an approach to create distributed user interfaces featuring procedures that are aimed to orchestrate user tasks over multiple Web sites. Our approach supports flexible process modeling by allowing users to combine manual tasks and automated tasks from a repertoire of patterns of tasks performed over the Web. In our approach, whilst manual tasks can be regarded as simple instructions that tell users how to perform a task over a Web site, automated tasks correspond to tools built under the concept of Web augmentation (as it augments the repertoire of tasks users can perform over the Web) called Web augmenters. Both manual and automated tasks are usually supported by specific DOM elements available in different Web sites. Thus, by combining tasks and DOM elements distributed in diverse Web sites our approach supports the creation of procedures that allows seamless users interaction with diverse Web site. Moreover, such an approach is aimed at supporting the collaboration between users sharing procedures. The approach is duly illustrated by a case study describing a collaborative trip planning over the Web.