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ADAPTING BOYER-MOORE-LIKE algorithms FOR SEARCHING HUFFMAN ENCODED TEXTS

INTERNATIONAL JOURNAL OF FOUNDATIONS OF COMPUTER SCIENCE 2012年第2期23卷 343-356页

作者： Cantone, Domenico Faro, Simone Giaquinta, Emanuele Univ Catania Dipartimento Matemat & Informat Viale A Doria 6 I-95125 Catania Italy

In this paper we propose an efficient approach to the compressed string matching problem on Huffman encoded texts, based on the BOYER-MOORE strategy. Once a candidate valid shift has been located, a subsequent verification phase checks whether the shift is codeword aligned by taking advantage of the skeleton tree data structure. Our approach leads to algorithms that exhibit a sublinear behavior on the average, as shown by extensive experimentation.

关键词： String matching compression algorithms Huffman coding Boyer-Moore algorithm text processing information retrieval

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CLUE: Achieving Fast Update over Compressed Table for Parallel Lookup with Reduced Dynamic Redundancy

CLUE: Achieving Fast Update over Compressed Table for Parall...

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32nd IEEE International Conference on Distributed Computing Systems (ICDCS)

作者： Yang, Tong Duan, Ruian Lu, Jianyuan Zhang, Shenjiang Dai, Huichen Liu, Bin Tsinghua Univ Dept Comp Sci & Technol Tsinghua Natl Lab Informat Sci & Technol Beijing 100084 Peoples R China

ISBN: (纸本)9781457702952

The sizes of routing table in backbone routers continue to keep a rapid growth and some of them currently increase up to 400K entries [1]. An effective solution to deflate the large table is the routing table compression. Meanwhile, there is an increasingly urgent demand for fast routing update mainly due to the change of network topology and new emerging Internet functionalities. Furthermore, the Internet link transmission speed has scaled up to 100Gbps commercially and towards 400Gbps Ethernet for laboratory experiments, resulting in a raring need of ultra-fast routing lookup. To achieve high performance, backbone routers must gracefully handle the three issues simultaneously: routing table compression, fast routing Lookup, and fast incremental UpdatE (CLUE), while previous works often only concentrate on one of the three dimensions. To address these issues, we propose a complete set of solutions-CLUE, by improving previous works and adding a novel incremental update mechanism. CLUE consists of three parts: a routing table compression algorithm, an improved parallel lookup mechanism, and a new fast incremental update mechanism. The routing table compression algorithm is based on ONRTC algorithm [2], a base for fast TCAM parallel lookup and fast update of TCAM. The second part is the improvement of the logical caching scheme for dynamic load balancing parallel lookup mechanism [3]. The third one is the conjunction of the trie, TCAM and redundant prefixes update algorithm. We analyze the performance of CLUE by mathematical proof, and draw the conclusion that speedup factor is proportional to the hit rate of redundant prefixes in the worst case, which is also confirmed by experimental results. Large-scale experimental results show that, compared with the mechanism in [3], CLUE only needs about 71% TCAM entries, 4.29% update time, and 3/4 dynamic redundant prefixes for the same throughput when using four TCAMs. In addition, CLUE has another advantage over the mechanis

关键词： route list backbone router Telecommunications Access Method hit rate Fasting refresh time speedup factor Redundant formal proof control surfaces compression algorithms

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An Adaptive, Scalable, and Portable Technique for Speeding Up MPI-Based Applications

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18th International Conference on Euro-Par Parallel Processing

作者： Filgueira, Rosa Atkinson, Malcolm Nunez, Alberto Fernandez, Javier Univ Edinburgh Sch Informat Edinburgh EH8 9AB Midlothian Scotland Univ Complutense Madrid Dept Sistemas Informat Computac Madrid 28040 Spain Univ Carlos III Madrid Dept Arquitectura Comp Leganes 3028911 Spain

ISBN: (纸本)9783642328206

This paper presents a portable optimization for MPI communications, called PRAcTICaL-MPI (Portable Adaptive compression Library- MPI). PRAcTICaL-MPI reduces the data volume exchanged among processes by using lossless compression and offers two main advantages. Firstly, it is independent of the MPI implementation and the application used. Secondly, it allows for turning the compression on and off and selecting the most appropriate compression algorithm at runtime, depending on the characteristics of each message and on network performance. We have validated PRAcTICaL-MPI in different MPI implementations and HPC clusters. The evaluation shows that compressing MPI messages with the best algorithm and only when it is worthwhile, we obtain a great reduction in the overall execution time for many of the scenarios considered.

关键词： MPI Library Parallel techniques High-Performance Computing compression algorithms Adaptive systems Portable optimizations

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Systematic Approaches for PI System ™ Data compression Tuning

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IFAC Proceedings Volumes 2012年第15期45卷 309-313页

作者： Rodrigo P. Silveira Jorge O. Trierweiler Marcelo Farenzena Herbert C. Teixeira Departamento de Engenharia Química Escola de Engenharia Universidade Federal do Rio Grande do Sul Brazil (Tel: +55 51 3308-4167) Centro de Pesquisas e Desenvolvimento Leopoldo Américo M. de Mello (CENPES) PETROBRAS Brazil

The consolidation of automation in the process industry has brought a challenge: translate the large volume of data in useful information. The algorithms for plant data compression emerge as an alternative to reduce the space demanded by such information. On the other hand, they should preserve the important features that data hold. PI ™ ( Plant Information , OSIsoft ® ) is a virtual tool structured to automate the collection, historization and displaying data of companies. Nevertheless, the efficiency of the compression algorithm used in this system is often not satisfactory, because of poor tuning. This paper presents two methodologies to automate the tuning of process parameters for data compression of PI ™ , based on a representative dataset extracted from the measurements. The applicability of the proposed techniques is corroborated by several case studies.

关键词： data compression data storage compression algorithms piecewise linear global optimization

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Tiled Image Container for Web Compatible Compound Image compression

Tiled Image Container for Web Compatible Compound Image Comp...

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International IEEE Conference on Signal-Image Technologies and Internet-Based System

作者： Ashok Mathew Kuruvilla Adobe Systems Inc.

Encoding images containing mixed content in web compatible formats like PNG, GIF and JPEG poses challenges in maintaining the quality along with good compression. In this paper, we describe a method for improving the compression of web compatible compound images while retaining high quality. The proposed method is based on the principle that the compression ratio of a given image depends upon both the image content and the compression algorithm used. Therefore, encoding various tiled regions in a given image with the algorithm appropriate to the content in the region improves the overall compression of the image. Further optimizations like sharing of indexed colors between the various tiles in the same image and removal of duplicate tiles improve the compression. This method would support both lossy and loss less compression. The resulting encoded data can be rendered by a web browser supporting CSS background-cropping or HTML5 canvas APIs.

关键词： Tiles Image coding Image color analysis Transform coding compression algorithms Compounds Image reconstruction

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Searching for optimal alphabet for data compression using simulated annealing

Searching for optimal alphabet for data compression using si...

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IEEE International Conference on Systems, Man and Cybernetics

作者： Jan Platos Pavel Kromer Department of Computer Science FEECS VSB-Technical University of Ostrava Ostrava Poruba Czech Republic

Data compression is very important today and it will be even more important in the future. Textual data use only limited alphabet - total number of used symbols (letters, numbers, diacritics, dots, spaces, etc.). In most languages, letters are joined into syllables and words. All three approaches are useful in text compression, but none of them is the best for any file. This paper describes a variant of algorithm for evolving alphabet from characters, 2-grams and 3-grams, which is optimal for compression of text files. We used Simulated Annealing for this evolution of the alphabet. The efficiency of the new variant will be tested on four compression algorithms. The achieved results are very promising.

关键词： compression algorithms Data compression Simulated annealing Encoding Genetic algorithms Cooling

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Performance analysis of a 2-D EEG compression algorithm using an automatic seizure detection system

Performance analysis of a 2-D EEG compression algorithm usin...

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Asilomar Conference on Signals, Systems & Computers

作者： Hoda Daou Fabrice Labeau Department of Electrical and Computer Engineering McGill University Montreal QUE Canada

ISBN: (纸本)9781467350501

A recently developed compression algorithm that uses DWT, SPIHT and smoothness transforms to compress EEG channels in 2-D proved to give very low distortion values for high compression ratios. Although RD performance is a commonly used metric in signal compression, in medical signals, it is important to preserve important diagnostic information. In order to move towards such a diagnostics-oriented performance assessment, we propose in this paper a framework to evaluate the performance of EEG compression mechanisms in terms of post-compression seizure detection capability. In particular, we show that the above-mentioned 2-D algorithm can maintain diagnostic features down to bitrates of 2 bits per sample.

关键词： EEG DWT SPIHT Electroencephalography compression algorithms compression ratio D-Algorithm signal compression diagnostic message Seizures Detection systems Bit rate

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Improving compression Using Words

Improving Compression Using Words

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International Conference on Intelligent Networking and Collaborative Systems (INCOS)

作者： Jan Platos Pavel Kromer Department of Computer Science FEECS VSB-Technical University of Ostrava Ostrava Poruba Czech Republic

General compression algorithms were designed for usage characters as basic symbols. Later, algorithm which used words were developed. The problem is that there is no clear line which defines if is better to use characters or words. In this paper, we developed optimization algorithm based on simulated annealing that selects only several words from all possible words and combine them with character to improve overall compression. The achieved results are very promising.

关键词： Data compression compression algorithms Simulated annealing Genetic algorithms Channel coding

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A novel scheme of orientation and scale mapped RDC (OS-RDC) to improve compression in document images ensuring quality preservation

A novel scheme of orientation and scale mapped RDC (OS-RDC) ...

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International Conference on Pattern Recognition

作者： Apurba Das R Remya Imaging Tech Lab. HCL Technologies Ltd. Chennai India

Repeated appearance of any block of spatial data in document images can be cached and encoded single time to get good compression ratio. This Reusable Document Component (RDC) can replicate the blocks of each redundant image at the receiver side at different positions but with same size and orientation. We have proposed a novel algorithm of Orientation Scale mapped RDC (OS-RDC) which can identify and cache repeated image blocks even if they are of different size and orientations. Both the inter-page and intra-page redundancies are addressed ensuring significant quality preservation.

关键词： Image coding Image segmentation Conferences Transforms Printing compression algorithms PSNR

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A Ubiquitous Data Logger that Selects an Efficient Data compression Method

A Ubiquitous Data Logger that Selects an Efficient Data Comp...

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International Conference on Advanced Information Networking and Applications Workshops (AINAW)

作者： Kenji Ono Tsutomu Terada Masahiko Tsukamoto Graduate School of Engineering Kobe University Kobe Japan

ISBN: (纸本)9781467308670

Recently, ubiquitous computing has been garnering a great deal of attention. In ubiquitous computing environments, sensor nodes connected to a network are used for collecting sensor data. However, considering the cost needed to set up the network, it may be more convenient to use data loggers that directly send data to users than to use a sensor network. In this paper, we propose a ubiquitous data logger that takes sensor characteristics into consideration in managing data. The logger reduces data volume by selecting an appropriate compression algorithm that takes sensor characteristics into consideration, because the sensor characteristics vary depending on the sensor data.

关键词： Approximation methods Data compression compression algorithms Accelerometers Ubiquitous computing Humidity Educational institutions

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