检索结果-内蒙古大学图书馆

Speeding up fractal image compression by genetic algorithms

MULTIDIMENSIONAL systems AND SIGNAL PROCESSING 2005年第2期16卷 217-236页

作者： Mohamed, F Aoued, B Department of Computer Science Evolutionary Engineering and Distributed Information Systems Laboratory EEDIS University of Sidi Bel-Abbès Algeria Department of Electronics Communications Networks Architectures and Multimedia Laboratory University of Sidi Bel Abbès Algeria

The main problem with all fractal compression implementation is execution time. Algorithms can spend hours to compress a single image. Most of the major variants of the standard algorithm for speeding up computation time have led to a bad-quality or a lower compression ratio. For example, the Fisher's [ 7] proposed classification pattern greatly accelerated the algorithm, but image quality was poor due to the search-space reduction imposed by the classification, which eleminates a lot of good solutions. By using genetic algorithms to address the problem, we optimize the domain blocks search. We explore all domain blocks present in the image but not in exhaustive way ( like a standard algorithm) and without omitting any possible block (solution) as a classification pattern does. A genetic algorithm is the unique method for satisfying these constraints. And it is a way to do be a random search because the genetic one is directed by fitness selection, which produces optimal solutions. Our goal in this work is to use a genetic algorithm to solve the IFS inverse problem and to build a fractal compression algorithm based on the genetic optimization of a domain blocks search. we have also implemented standard Barnsley algorithm, the Y. Fisher based on classification, and the genetic compression algorithm with quadtree partitioning. A population of transformations was evolved for each range block, and the result is compared with the standard Barnsely algorithm and the Fisher algorithm = based classification. We deduced an optimal set of values for the best parameters combination, and we can also specify the best combination for each desired criteria: best compression ratio, best image quality, or quick compression process. By running many test images, we experimentally found the following set of optimal values of all the algorithm parameters that ensure compromise between execution time and solutions optimality: Population size = 100, Maximum generations = 20, Crossover rat

关键词：

来源：评论

学校读者我要写书评

暂无评论

An integration of Global and Enterprise Grid computing: Gridbus Broker and Xgrid perspective

引用

4th International Conference on Grid and Cooperative Computing - GCC 2005

作者： De Assunção, Marcos Dias Nadiminti, Krishna Venugopal, Srikumar Ma, Tianchi Buyya, Rajkumar Grid Computing and Distributed Systems Laboratory Australia Department of Computer Science and Software Engineering University of Melbourne Parkville Campus Melbourne Vic. 3010 Australia

ISBN: (纸本)3540305106

In this work, we present two perspectives of Grid computing by using two different Grid middleware as examples: an Enterprise Grid using Xgrid and a Global Grid with Gridbus. We also present the integration of Enterprise and Global Grids by proposing the integration of Gridbus Broker with diverse enterprise Grid middleware including Xgrid, PBS, Condor and SGE. The sample performance results demonstrate the usefulness of this integration effort. © Springer-Verlag Berlin Heidelberg 2005.

关键词： distributed computer systems

来源：评论

学校读者我要写书评

暂无评论

The grid economy

The grid economy

引用

作者： Buyya, Rajkumar Abramson, David Venugopal, Srikumar Grid Computing and Distributed Systems Laboratory Department of Computer Science and Software Engineering University of Melbourne Vic. 3010 Australia School of Computer Science and Software Engineering Monash University Vic. 3163 Australia

This paper identifies challenges in managing resources in a Grid computing environment and proposes computational economy as a metaphor for effective management of resources and application scheduling. It identifies distributed resource management challenges and requirements of economy-based Grid systems, and discusses various representative economy-based systems, both historical and emerging, for cooperative and competitive trading of resources such as CPU cycles, storage, and network bandwidth. It presents an extensible, service-oriented Grid architecture driven by Grid economy and an approach for its realization by leveraging various existing Grid technologies. It also presents commodity and auction models for resource allocation. The use of commodity economy model for resource management and application scheduling in both computational and data grids is also presented. © 2005 IEEE.

关键词： Computational methods

来源：评论

学校读者我要写书评

暂无评论

Adopting a component-based software architecture for an industrial control system - A case study

引用

Lecture Notes in computer science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) 2005年 3778 LNCS卷 232-248页

作者： Lüders, Frank Crnkovic, Ivica Runeson, Per Department of Computer Science and Engineering Mälardalen University Box 883 SE-721 23 Västerås Sweden Department of Communication Systems Lund University Box 118 SE-221 00 Lund Sweden

ISBN: (纸本)3540306447

This chapter presents a case study from a global company developing a new generation of programmable controllers to replace several existing products. The system needs to incorporate support for a large number of I/O systems, network types, and communication protocols. To leverage its global development resources and the competency of different development centers, the company decided to adopt a component-based software architecture that allows I/O and communication functions to be realized by independently developed components. The architecture incorporates a subset of a standard component model. The process of redesigning the software architecture is presented, along with the experiences made during and after the project. An analysis of these experiences shows that the component-based architecture effectively supports distributed development and that the effort required for implementing certain functionality has been substantially reduced while, at the same time, the system's performance and other run-time quality attributes have been kept on a satisfactory level. © Springer-Verlag Berlin Heidelberg 2005.

关键词： Software architecture

来源：评论

学校读者我要写书评

暂无评论

Providing Hard Real-Time Guarantees in Context-Aware Applications: Challenges and Requirements

Providing Hard Real-Time Guarantees in Context-Aware Applica...

引用

IEEE International Symposium on Network Computing and Applications

作者： M. Boulkenafed B. Hughes R. Meier G. Biegel V. Cahill Department of Computer Science Distributed Systems Group Dublin Ireland

Context-aware applications rely on the ability to perceive the state of the surrounding environment. In this paper, we address a class of such applications where real-time guarantees are required on top of mobile ad hoc networks. While guaranteed timeliness is a critical requirement, the unpredictability of dynamic wireless networks adversely impacts such guarantees. Therefore, we identify the challenges and the requirements on different architectural levels in order to provide timeliness guarantees. None of the existing systems have succeeded in providing adequate solutions to all of the identified requirements. Therefore, we describe a cross-layer architecture that supports the development of real-time context-aware applications for wireless networks, in particular, ad hoc networks. This cross-layer architecture is based on three main components. (i) Sentient objects - mobile intelligent software agents that extract, interpret and use context information. (ii) Event-based real-time middleware supports communication between sentient objects and provides hard real-time guarantees within adaptable geographic spaces. (iii) A real-time routing and resource reservation protocol attempts to discover and maintain real-time constrained routes within these proximities in a multi-hop ad hoc network

关键词： Wireless networks computer architecture Context Ad hoc networks Mobile ad hoc networks Application software Intelligent agent Intelligent networks Software agents Data mining

来源：评论

学校读者我要写书评

暂无评论

Physical layer performance benchmarking of two metropolitan area network configurations

引用

Optical Switching and Networking 2005年第1期2卷 19-33页

作者： Sygletos, S. Skoufis, C. Matrakidis, C. Stavdas, A. LeSauze, N. Chiaroni, D. Institute of Communication and Computer Systems National Technical University of Athens Athens Greece Department of Telecommunications Science and Technology University of Peloponnese Tripolis Greece Alcatel CIT Research and Innovation Route de Nozay Marcoussis France

The current downturn in the telecommunications sector is imposing a major rethinking as regards the objectives and introductory time frame of optical networking. This is even truer in cost-sensitive segments like metropolitan networks. All-optical solutions will be introduced in a step-by-step approach and the intermediate stages need to be carefully thought out and planned in advance. In this work, two MAN solutions-one short term one using mature technologies and one longer term one using advanced ones-are benchmarked with respect to their physical layer performance. Subsequent variants of the baseline configuration deploying fewer and/or less demanding/lower performance components and subsystems are assessed to identify the trade-offs between performance and cost. It is shown via simulations that a metropolitan network of 1.28 Tb/s capacity can be constructed using four rings of 320 Gb/s capacity each. The geographic extension of such a ring could span up to 160 km with both solutions. It is also demonstrated that the technologically advanced solution is more robust when components with realistic performance are taken into account while it is able to cover a wider geographic range. © 2005 Elsevier B.V. All rights reserved.

关键词： Metropolitan area networks

来源：评论

学校读者我要写书评

暂无评论

A flexible BDI architecture supporting extensibility

A flexible BDI architecture supporting extensibility

引用

IEEE/WIC/ACM International Conference on Intelligent Agent Technology (IAT)

作者： A. Pokahr L. Braubach W. Lamersdorf Distributed Systems and Information Systems Computer Science Department University of Hamburg Germany

The BDI agent model comprises a simple but efficient folk psychological framework of mentalistic notions usable for modeling rational agent behaviour. Nevertheless, despite its usefulness it is also a popular subject for extensions that try to improve the model in certain uncovered aspects such as emotions or norms. On the architectural level the BDI model is typically represented by an abstract BDI interpreter, which implements the fixed BDI reasoning cycle. In this paper it is argued that a fixed cycle has certain inherent drawbacks and that a transition towards a flexible agenda approach based on BDI meta-actions leads to a design open for extensions in many respects because new meta-actions can be easily integrated into the architecture on demand. To prove the validity of the approach, it is shown how the extensibility can be exploited to integrate concrete new aspects of increasing complexity into the model. They range from a simple mechanism for updating beliefs to a complex goal deliberation strategy and demand only slight modifications at well-defined extension points of the architecture. The new architecture as well as the presented extensions has been realized within the open source Jadex BDI reasoning engine.

关键词： Humans Psychology Concrete computer architecture Information systems computer science Engines Cognition Learning systems Teamwork

来源：评论

学校读者我要写书评

暂无评论

A peer-to-peer mechanism for resource location and allocation over the grid

引用

2nd International Symposium on Parallel and distributed Processing and Applications, ISPA 2004

作者： Hsiao, Hung-Chang Baker, Mark King, Chung-Ta Computer and Communication Research Center National Tsing-Hua University 300 Taiwan The Distributed Systems Group University of Portsmouth PO1 2EG United Kingdom Department of Computer Science National Tsing-Hua University 300 Taiwan

ISBN: (纸本)9783540241287

Recent advances in P2P lookup overlays provide an appealing solution for distributed search without relying on a single database server. In addition to performing resource discovery, these P2P substrates also offer membership management for dynamic peers. In this paper, we propose a publicly shared architecture called VC2A that takes advantage of a P2P lookup substrate for computational applications. VC2A targets computational master-slave applications. An application running in VC2A dynamically allocates resources from the system on the fly. These allocated resources then self-manage and -heal. We have implemented an architecture based on our previous efforts that include an enhanced P2P lookup overlay and a mobile agent system on top of this overlay. We show that VC2A is not only scalable but robust, and takes advantage of heterogeneity of the resources. © Springer-Verlag Berlin Heidelberg 2004.

关键词： Substrates

来源：评论

学校读者我要写书评

暂无评论

distributed mining of partial periodic patterns in sequences

Distributed mining of partial periodic patterns in sequences

引用

作者： Hsiao, Han-Wen Tsai, Meng-Shu Tsai, Jeffrey J. P. Department of Computer Science and Information Engineering Asia University Taiwan Taiwan Institute of Information Technology Asia University Taiwan Taiwan Department of Computer Science University of Illinois Chicago United States Taichung Healthcare and Management University Department of Computer Science and Information Engineering Department of Biotechnology and Bioinformatics Department of Electrical Engineering and Computer Science University of Illinois Chicago Distributed Real-Time Intelligent Systems Laboratory

It has been an important task of discovering frequent fragments as particular patterns from large sequence databases generated from a variety of applications. In general, the patterns to be discovered may partially and asynchronously exist in sequences, and even contain gaps. In addition, it is necessary to collect the information regarding the locations and frequencies of the patterns. How to enumerate candidate patterns for evaluation without exponentially increasing the computation is another problem. In this paper, the modified periodicity transform is proposed to meet the requirements mentioned above. Also, a distributed computing framework is implemented to perform the mining task more efficiently. Both synthetic and biological sequences are utilized to examine the approach. The experimental results demonstrate the efficiency and effectiveness the system.

关键词： Data mining

来源：评论

学校读者我要写书评

暂无评论

Best fitting fixed-length substring patterns for a set of strings

引用

11th Annual International Conference on Computing and Combinatorics, COCOON 2005

作者： Ono, Hirotaka Ng, Yen Kaow Kyushu University Department of Computer Science and Communication Engineering 6-10-1 Hakozaki Fukuoka812-8581 Japan Kyushu Institute of Technology Graduate School of Computer Science and Systems Engineering Iizuka820 Japan

ISBN: (纸本)9783540280613

Finding a pattern, or a set of patterns that best characterizes a set of strings is considered important in the context of Knowledge Discovery as applied in Molecular Biology. Our main objective is to address the problem of "over-generalization", which is the phenomenon that a characterization is so general that it potentially includes many incorrect examples. To overcome this we formally define a criteria for a most fitting language for a set of strings, via a natural notion of density. We show how the problem can be solved by solving the membership problem and counting problem, and we study the runtime complexities of the problem with respect to three solution spaces derived from unions of the languages generated from fixed-length substring patterns. Two of these we show to be solvable in time polynomial to the input size. In the third case, however, the problem turns out to be NP-complete. © Springer-Verlag Berlin Heidelberg 2005.

关键词： Molecular biology

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：