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International Conference on Networking, International Conference on systems andInternational Conference on Mobile Communications and Learning Technologies, ICN/ICONS/MCL'06

作者： Bidese De Pinho, Leonardo Luis De Amorim, Claudio COPPE Systems Engineering Program Federal University of Rio de Janeiro Brazil

ISBN: (纸本)0769525520

In this work we propose Early Released First (ERF) and Bounded ERF (BERF) two new application-friendly heuristics that support scalable delivery of video-on-demand (VoD) to mobile devices. The key idea behind ERF and BERF heuristics is to exploit the slack of time known as the patience factor that VoD applications typically provide. To evaluate the benefits of ERF and BERF we coupled them to the Wireless Channel Manager (WCM) an association control unit we developed previously that schedules clients to collocated access points (APs) operating on 802.11 networks. Our simulated results indicated that ERF and BERF reduced overall blockage rate of video requests significantly and that the resulting system, which we called Cluster of INexpensive Access PointS (CINAPS), showed considerable scalability gains on VoD delivery. © 2006 IEEE.

关键词： Video on demand

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A column generation approach for solving very large scale instances of the brazilian long term power expansion planning model 17

A column generation approach for solving very large scale in...

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17th Power systems Computation Conference, PSCC 2011

作者： De Sabóia, Carlos Henrique Medeiros Lucena, Abilio CEPEL Electric Power Research Center COPPE/UFRJ Systems Engineering Program Rio de Janeiro Brazil UFRJ Faculty of Management COPPE/UFRJ Systems Engineering Program Rio de Janeiro Brazil

ISBN: (纸本)9789175012575

This paper applies the Dantzig-Wolfe decomposition principle to the mixed integer programming based Brazilian long term power expansion planning model. Since no formulation closely resembling the specific details we have to address could be found in the literature, we had to impose significant modifications to a Dantzig-Wolfe based reformulation and solution algorithm previously suggested for a power planning application. As a result, minimum mandatory thermal power plants operation levels could be imposed and were adequately dealt with within a column generation scheme. The solution algorithm we implemented initially suffered from severe stabilization problems. These were eventually settled through a nonstandard procedure we suggested and the algorithm then proved quite effective. Indeed, it was capable of solving very large scale real world instances of our planning problem, to an optimality guarantee of 1% or less. For some of these instances, such a guarantee is currently out of reach of state-of-the-art commercial optimization software.

关键词： Integer programming

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Towards the conception of scientific workflows for in silico experiments in software engineering 10

Towards the conception of scientific workflows for in silico...

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Proceedings of the 2010 ACM-IEEE International Symposium on Empirical Software engineering and Measurement

作者： Pereira, Wallace M. Travassos, Guilherme H. Federal University of Rio de Janeiro/COPPE Systems Engineering and Computer Science Program Brazil

ISBN: (纸本)9781450300391

The evolution of Science has been supported by complex computerized infrastructures with growing interest in simulation based experiments. This trend can also be observed in Software engineering. Our capacity of acquiring evidences to describe phenomena of interest in the field allowed the building of in silico models that can virtually replicate feasible software behaviors and improve our capacity of observation. In silico experiments demand additional concerns for its planning. One of them is regarding the scientific workflow conception. This task is not easy and to apply ad-hoc approaches can risky the experiment execution, validity and future replications. Regarding this topic, this paper presents some initial results from our research towards an approach to support the conception of scientific workflows for in silico experiments in Software engineering are presented. © 2010 ACM.

关键词： Computer software

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Towards supporting the specification of context-aware software system test cases 23

Towards supporting the specification of context-aware softwa...

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23rd Iberoamerican Conference on Software engineering, CIbSE 2020

作者： de Souza Doreste, Andréa Cristina Travassos, Guilherme Horta Systems Engineering and Computer Science Program COPPE Federal University of Rio de Janeiro Brazil

In Software engineering, context can be understood as the overall set of information used to characterize the situation of an entity. A software system is context-aware if it uses the context to provide relevant information or services to the user. Nowadays, different types of software systems with a profound impact on the user's life can be considered context-aware (e.g., ubiquitous and Internet of Things software systems). Therefore, it is crucial to guarantee that they behave correctly. Software Testing is the primary process for verifying system behavior. Because of the particularities of Context-Aware Software systems (CASS), conventional testing methods are not enough to test such systems. Based on that, we propose CATS#, a technique to support software engineers with the specification of CASS test cases and capture not only the context itself but its variation as well. CATS# is an evolution of the CATS (Context-Aware Test Suite) Design technique. It introduces two relevant evolutions: test case models and a new test template. The test case models were proposed after we searched for context-aware applications through the literature and realized that the context could affect the test process in different manners. The test template was proposed to capture the variation of context by specifying which variation should occur during the test case and when it should occur. We selected one example application to apply our technique, deriving different types of test cases and showing its relevance in these initial steps. © CIbSE 2020.

关键词： Software testing

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U-Net and SegNet performances on lesion segmentation of breast ultrasonography images

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Research on Biomedical engineering 2021年第2期37卷 171-179页

作者： Vianna, Pedro Farias, Ricardo de Albuquerque Pereira, Wagner Coelho Biomedical Engineering Program COPPE/Federal University of Rio de Janeiro Av. Horácio Macedo 2030 Room H327 Rio de JaneiroRJ Brazil Systems and Computing Engineering Program COPPE/Federal University of Rio de Janeiro Rio de JaneiroRJ Brazil

Purpose: Screening is the predominant strategy for the early detection of breast cancer. However, image analysis depends on the experience of the radiologist, inserting subjective factors in the evaluation of findings. Most biopsies performed on women with suspicious lesions on breast imaging tests show benignity. This medical technique is invasive and consumes time and resources;therefore, there is a demand to reduce these unnecessary procedures. Computer-aided diagnostics has been increasingly used as a second-reader tool lately, decreasing the diagnostic uncertainty of specialists. Based on this fact, the development of such systems is crucial and can be accomplished by the refinement of its steps, i.e., more accurate segmentation and classification. Considering this scenario, the present work describes the implementation of two well-known convolutional neural networks, U-Net and SegNet, for the segmentation of lesions found in breast ultrasonography. Defining which architecture is most appropriate for this task can ultimately help in reducing the number of biopsies performed. Methods: Convolutional neural networks are used in segmentation by classifying each pixel in an image, based on self-trained weights. Using a dataset of 2054 images, obtained in partnership with the National Cancer Institute, we compared the automatic segmentation performed by the networks with a manual segmentation made by a specialist. Results: Among the two proposed architectures, U-Net obtained better results in this task, obtaining a dice coefficient of 86.3%, and took 68.3% less training time than the SegNet, which achieved a dice score of 81.1%. Conclusion: The two networks can segment ultrasound images with useful accuracy depending on their configuration, with U-Net being faster to train and more accurate. © 2021, Sociedade Brasileira de Engenharia Biomedica.

关键词： Semantic Segmentation

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ELM vs. WiSARD: A performance comparison 25

ELM vs. WiSARD: A performance comparison

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25th European Symposium on Artificial Neural Networks, Computational Intelligence and Machine Learning, ESANN 2017

作者： Oliveira, Luiz Fernando R. França, Felipe M.G. Systems Engineering and Computer Science Program COPPE Universidade Federal Do Rio de Janeiro Brazil

ISBN: (纸本)9782875870391

The extreme learning machine (ELM) is known for being a fast learning neural model. This work presents a performance comparison between ELM and the WiSARD weightless neural network model, regarding training and testing times, and classification accuracy as well. The two models were implemented in the same programming language and experiments were carried out on the same hardware environment. By using a group of datasets from the public repositories UCI and Statlog, experimental results shows that the WiSARD presented training times approximately one order of magnitude smaller than ELM, while classification accuracy varied according the number of classes involved. However, while WiSARD's architecture setups were not exhaustively searched, architecture setups for ELM were kept the same as the ones found in the literature as the best for each given dataset. © ESANN 2017 - Proceedings, 25th European Symposium on Artificial Neural Networks, Computational Intelligence and Machine Learning. All rights reserved.

关键词： Classification (of information)

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Systematic mapping on the use of games for software engineering education 23

Systematic mapping on the use of games for software engineer...

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23rd Iberoamerican Conference on Software engineering, CIbSE 2020

作者： Castro, Diego Costa, Diogo Matheus Werner, Cláudia Maria Lima COPPE/Computer Systems Engineering Program Federal University of Rio de Janeiro Rio de Janeiro Brazil

Games appeal to all kinds of people and are used for a wide range of purposes, from pure entertainment to educational research. Software engineering is an area of computing that has much content to explore, distributed in different knowledge areas. Thus, there are many theoretical classes that make learning tiresome. In this scenario, educators and researchers are looking for new methods to engage students in order to facilitate the learning process. Many studies have already been produced using games as a teaching method. However, a recurring mistake when using games as a teaching method is the application of the wrong approach to a context that often hinders student learning. This paper presents a systematic mapping that aims to identify the main ways that games are being used as a teaching method focused on Software engineering. The results highlight five ways of using games as a teaching method, where Game-based Learning, Digital Game-based Learning and Gamification are the most used ones. © CIbSE 2020.

关键词： Serious games

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Formalizing the situation of a business process activity

Formalizing the situation of a business process activity

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2012 IEEE 16th International Conference on Computer Supported Cooperative Work in Design, CSCWD 2012

作者： Mattos, Talita Da Cunha Santoro, Flávia Maria Revoredo, Kate Nunes, Vanessa Tavares Postgraduate Information Systems Program UNIRIO Rio de Janeiro Brazil COPPE/PESC - Systems Engineering and Computer Science Program UFRJ Rio de Janeiro Brazil

ISBN: (纸本)9781467312127

Business processes are dynamic and constantly evolving. Contextual elements that had not yet been identified and represented can arise and influence the execution of each process instance in diverse manners. In this scenario, the identification of these elements is considered of great importance. This paper proposes a formalism for context associated with business processes that intends to identify the situation of an activity in order to subsidize decisions to be taken within the execution of a process. © 2012 IEEE.

关键词： Business Process Context

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Kairos: an architecture for securing authorship and temporal information of provenance Data in Grid-Enabled workflow management systems

Kairos: an architecture for securing authorship and temporal...

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4th IEEE International Conference on eScience, eScience 2008

作者： Gadelha Jr., Luiz M.R. Mattoso, Marta Computer and Systems Engineering Program - COPPE Federal University of Rio de Janeiro Rio de Janeiro Brazil

ISBN: (纸本)9780769535357

Secure provenance techniques are essential in generating trustworthy provenance records, where one is interested in protecting their integrity, confidentiality, and availability. In this work, we suggest an architecture to provide protection of authorship and temporal information in grid-enabled provenance systems. It can be used in the resolu-tion of conflicting intellectual property claims, and in the reliable chronological reconstitution of scientific experiments. We observe that some techniques from public key infrastructures can be readily applied for this purpose. We discuss the issues involved in the implementation of such architecture and describe some experiments realized with the proposed techniques. © 2008 IEEE.

关键词： Architecture

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An alternative QoS architecture for the IEEE 802.16 Standard 06

An alternative QoS architecture for the IEEE 802.16 Standard

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2nd Conference on Future Networking Technologies, CoNEXT'06

作者： De Moraes, Luís Felipe M. Maciel, Paulo Ditarso Systems Engineering and Computer Science Program - COPPE/UFRJ HighSpeed Networks Laboratory RAVEL Rio de Janeiro RJ Brazil

In this paper, we propose an alternative QoS architecture for the IEEE 802.16 Standard, that incorporates a priority based packet scheduling and a new traffic shaping. For this, we present the ideas of a traffic condi... 详细信息

ISBN: (纸本)1595934561

关键词： Quality of service

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