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作者： Benevides, Mario R.F. Schechter, L. Menasché Computer Science Department Systems and Computer Engineering Program Federal University of Rio de Janeiro Rio de Janeiro Brazil Systems and Computer Engineering Program Federal University of Rio de Janeiro Rio de Janeiro Brazil

Graphs are among the most frequently used structures in computer science. Some of the properties that must be checked in many applications are connectivity, acyclicity and the Eulerian and Hamiltonian properties. In this work, we analyze how we can express these four properties with modal logics. This involves two issues: whether each of the modal languages under consideration has enough expressive power to describe these properties and how complex (computationally) it is to use these logics to actually test whether a given graph has some desired property. First, we show that these properties are not definable in a basic modal logic or in any bisimulation-invariant extension of it, like the modal μ-calculus. We then show that it is possible to express some of the above properties in a basic hybrid logic. Unfortunately, the Hamiltonian and Eulerian properties still cannot be efficiently checked. In a second attempt, we propose an extension of CTL* with nominals and show that the Hamiltonian property can be more efficiently checked in this logic than in the previous one. In a third attempt, we extend the basic hybrid logic with the ↓ operator and show that we can check the Hamiltonian property with optimal (NP) complexity in this logic. Finally, we tackle the Eulerian property in two different ways. First, we develop a generic method to express edge-related properties in hybrid logics and use it to express the Eulerian property. Second, we express a necessary and sufficient condition for the Eulerian property to hold using a graded modal logic. © The Author 2009. Published by Oxford University Press. All rights reserved.

关键词： Model checking

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Elastic neural net algorithm for cluster analysis

Elastic neural net algorithm for cluster analysis

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Brazilian Symposium on Neural Networks

作者： R.L. Salvini L.A. V. de Carvalho Program of Systems Engineering and Computer Science COPPE/UFRJ Rio de Janeiro Brazil

Proposes a method for data clustering in a n-dimensional space using the elastic net algorithm which is a variant of the Kohonen topographic map learning algorithm. The elastic net algorithm is a mechanical metaphor in which an elastic ring is attracted by points in a bi-dimensional space while their internal elastic forces try to shun the elastic expansion. The different weights associated with these two kinds of forces lead the elastic to a gradual expansion in the direction of the bi-dimensional points. In this method, the elastic net algorithm is employed with the help of a heuristic framework that improves its performance for application in the n-dimensional space of cluster analysis. Tests were made with two types of data sets: (1) simulated data sets with up to 1000 points randomly generated in groups linearly separable with up to dimension 10 and (2) the Fisher Iris Plant database, a well-known database referred to in the pattern recognition literature. The advantages of the method presented are its simplicity, its fast and stable convergence, beyond efficiency in cluster analysis.

关键词： Neural networks Clustering algorithms Algorithm design and analysis Databases Performance analysis Testing Test pattern generators Iris Pattern recognition Convergence

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Metasurfaces for next-generation wireless communication systems

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National science Review 2023年第8期10卷 17-19页

作者： Younes Ra'di Nikita Nefedkin Petar Popovski Andrea Alù Department of Electrical Engineering and Computer Science Syracuse University Photonics Initiative Advanced Science Research Center City University of New York Department of Electronic Systems Aalborg University Physics Program Graduate Center City University of New York

The pace of development in the world of 5G communication systems has proven to be much more demanding than previous generations, with 5G-Advanced seemingly around the corner [1]. Extensive research is already underway to structure the next generation of wireless systems(i.e. 6G), which may potentially enable an unprecedented level of human–machine interaction [2].

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Towards a formal model to reason about context-aware exception handling

Towards a formal model to reason about context-aware excepti...

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2012 5th International Workshop on Exception Handling, WEH 2012

作者： Rocha, Lincoln S. Andrade, Rossana M. C. Group of Computer Networks Software Engineering and Systems Graduate Program in Computer Science Federal University of Ceará Fortaleza - CE Brazil

ISBN: (纸本)9781467317665

The context-awareness is a central aspect in the design of pervasive systems, characterizing their ability to adapt its structure and behavior. The context-aware exception handling (CAEH) is an existing approach employed to design exception handling in pervasive systems. In this approach, the context is used to define, detect, propagate, and handle exceptions. CAEH is a complex and error prone activity, needing designers' insights and domain expertise to identify and characterize contextual exceptions. However, despite the existence of formal methods to analyze the adaptive behavior of pervasive systems, such methods lack specific support to specify the CAEH behavior. In this paper, we propose a formal model to reason about the CAEH behavior. It comprises an extension of the Kripke Structure to model the context evolution of a pervasive system and a transformation function that derivates the CAEH control flow from that proposed structure. © 2012 IEEE.

关键词： Model checking

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A verification mechanism of feature models for mobile and context-aware software product lines

A verification mechanism of feature models for mobile and co...

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5th Brazilian Symposium on Components, Architectures and Reuse, SBCARS 2011

作者： Marinho, Fabiana G. Andrade, Rossana M.C. Werner, Cláudia Graduate Program in Computer Science Federal University of Ceará Fortaleza Brazil Systems Engineering and Computer Science Program Federal University of Rio de Janeiro Rio de Janeiro Brazil

ISBN: (纸本)9780769546261

Software Product Lines (SPLs) have been used to develop mobile and context-aware applications, which provide services and data for their users from anywhere and at any time using context information. In SPLs, commonality and variability of a system family are identified and often documented in a feature model. However, the development of a feature model for mobile and context-aware SPLs is not trivial, since it should comprise system and context information. Furthermore, the consistency check of feature models in the considered domain is also complex and demands advanced skills of software engineers. This paper proposes a mechanism to formalize and verify the correctness and consistency of feature models for mobile and context-aware SPLs based on a profile enriched with OCL specifications. © 2011 IEEE.

关键词： Verification

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Deep Semantic and Attentive Network for Unsupervised Video Summarization

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ACM Transactions on Multimedia Computing, Communications and Applications 2022年第2期18卷 1-21页

作者： Zhong, Sheng-Hua Lin, Jingxu Lu, Jianglin Fares, Ahmed Ren, Tongwei College of Computer Science and Software Engineering Shenzhen University Shenzhen518060 China Department of Electrical Engineering Computer Systems Engineering Program Faculty of Engineering at Shoubra Benha University Cairo Egypt State Key Laboratory for Novel Software Technology Nanjing University Nanjing210023 China

With the rapid growth of video data, video summarization is a promising approach to shorten a lengthy video into a compact version. Although supervised summarization approaches have achieved state-of-the-art performance, they require frame-level annotated labels. Such an annotation process is time-consuming and tedious. In this article, we propose a novel deep summarization framework named Deep Semantic and Attentive Network for Video Summarization (DSAVS) that can select the most semantically representative summary by minimizing the distance between video representation and text representation without any frame-level labels. Another challenge associated with video summarization tasks mainly originates from the difficulty of considering temporal information over a long time. Long Short-Term Memory (LSTM) performs well for temporal dependencies modeling but does not work well with long video clips. Therefore, we introduce a self-attention mechanism into our summarization framework to capture the long-range temporal dependencies among the frames. Extensive experiments on two popular benchmark datasets, i.e., SumMe and TVSum, show that our proposed framework outperforms other state-of-the-art unsupervised approaches and even most supervised methods. © 2022 Association for Computing Machinery.

关键词： Semantics

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Exploring parallelism in volume ray casting: Understanding the programming issues of multithreaded accelerators

Exploring parallelism in volume ray casting: Understanding t...

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2012 International Workshop on programming Models and Applications for Multicores and Manycores, PMAM 2012

作者： Cox, Guilherme Silva, Cleomar Cupertino, Leandro Bentes, Cristiana Farias, Ricardo Department of Computer Science Rutgers University United States Department of Electrical Engineering Pontifical Catholic University of Rio de Janeiro Brazil Department of Systems Engineering State University of Rio de Janeiro Brazil COPPE/Systems Engineering and Computer Science Federal University of Rio de Janeiro Brazil

ISBN: (纸本)9781450312110

Direct volume rendering of irregular 3D datasets demands high computational power and memory bandwidth. Recent research in optimizing volume rendering algorithms are exploring the high processing power offered by a new trend in hardware design: multithreaded accelerator devices. Accelerators like the Graphics Processing Units (GPU) and the Cell Broadband Engine processor (Cell BE) are used as integrated coprocessors, and the off-loading of the application from the CPU to the accelerator offers promising speedups. The difficulty in using these devices, however, is how to program them efficiently, since their architectural features may be completely distinct. In this paper, we present some new architectural-aware algorithms for irregular grid rendering based on the ray casting method, designed for the Cell BE and the GPU. We investigate the ray traversal inside each accelerator in terms of data access, load balancing, and code divergence, and find new opportunities for performance optimizations based on the ray casting specific needs. Our results show that squeezing these architectures for performance reveals their limitations and can significantly improve the ray casting efficiency. © 2012 ACM.

关键词： Parallel architectures

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Toward Parallelization Technique for Stream-based Lossless Data Compression

Toward Parallelization Technique for Stream-based Lossless D...

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2023 IEEE International Conference on Big Data, BigData 2023

作者： Kato, Taiki Yamagiwa, Shinichi Wada, Koichi Master's Program in Computer Science Degree Program in Systems and Information Engineering University of Tsukuba Ibalaki Tsukuba Japan University of Tsukuba Faculty of Engineering Information and Systems Ibalaki Tsukuba Japan

ISBN: (纸本)9798350324457

IoT edge platform has become popular in various distributed environments. The edge devices need to communicate BigData among them or with the cloud servers by collaborating with AI technologies for finding events from the applications. Those devices exchange data streams from such as distributed sensors and remote image/video devices. We focus on an acceleration technique for the communication performance using a stream-based lossless data compression technology. This paper proposes a parallelization technique for the compression process in a software environment running on a multicore processor. The technique invokes concurrent compression processes assigned to multiple threads with splitting a data stream to chunks. The paper exposes three scheduling methods for assigning the chunks to the threads: in-order, hybrid and out-of-order. As an original data order of chunks must be obtained in decompression side, the proposed technique introduces packeting mechanisms in each chunk by adding headers to support the scheduling methods. Through experimental performance evaluations, we discuss the packeting overhead focusing on compression ratio and speedup by the parallelization with three scheduling methods. © 2023 IEEE.

关键词： Data Stream IoT Lossless Data Compression Multi-Threading Parallelization

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Understanding the performance of DSM applications 1st

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1st Workshop on Communication and Architectural Support for Network-based Parallel Computing, CANPC 1997

作者： Meira, Wagner Leblanc, Thomas J. Hardavellas, Nikolaos Amorim, Clgudio Department of Computer Science University of Rochester RochesterNY14627 United States COPPE Systems Engineering UFRJ Rio de Janeiro21945-970 Brazil

ISBN: (纸本)3540625739

Carnival is a performance measurement and analysis tool that assists users in understanding the performance of DSM applications and protocols. Using traces of program executions, Carnival presents performance data as a hierarchy of execution profiles. During analysis, Carnival automates the inference process that relates performance phenomena to specific causes in the source code or DSM protocol using techniques that focus on the two most important sources of overhead in DSM systems: waiting time analysis identifies the causes of synchronization overhead, and produces an explanation for each source of waiting time in the program;communication analysis identifies the sequence of requests that result in invalidations, and produces an explanation for each source of communication. We describe these techniques and their implementation in TreadMarks, and show how to use waiting time analysis and communication analysis to improve the running time of two programs froIn the SPLASH application snite when executed on DEC Alphas connected by a DEC Memory Channel network. © Springer-Verlag Berlin Heidelberg 1997.

关键词： Application programs

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Performance Enhancement of Stream-Based Decompression Process by Notifying Compression Buffer Size 28

Performance Enhancement of Stream-Based Decompression Proces...

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28th IEEE Symposium on computers and Communications, ISCC 2023

作者： Kato, Taiki Yamagiwa, Shinichi Marumo, Koichi University of Tsukuba Master's Program in Computer Science Degree Program in Systems and Information Engineering Ibalaki Tsukuba Japan University of Tsukuba Faculty of Engineering Information and Systems Ibalaki Tsukuba Japan

ISBN: (纸本)9798350300482

This paper focuses on a performance enhancement of communication performance by compressing data stream. ASE coding is an effective lossless data compression method for data stream. The software implementation of the coding/decoding method inevitably meets a performance mismatch in memory and storage devices. In the compressor side, it is predictable to decide the size of an original data block and is available to process a flexible buffer memory. However, the decompressor is not able to predict the buffer size because the original data size is not obvious before the decompression. This causes a performance mismatch in the filesystem level. This paper proposes a novel method to address the performance mismatch by applying a notification mechanism of compression size from the compressor. This paper describes the mechanism focusing on the system call usage. Through experimental evaluations, we show the performance improvement of the decompression performance for handling data stream. © 2023 IEEE.

关键词： Virtual storage

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