DCA - Departamento de Engenharia de Computação

URI Permanente desta comunidadehttps://repositorio.ufrn.br/handle/1/128

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Agora exibindo 1 - 20 de 33

Algorítmo de mapeamento usando modelagem probabilística
(2007) Souza, Anderson A.; Medeiros, Adelardo Adelino Dantas de; Gonçalves, Luiz M. G.
Uma arquitetura distribuída de hardware e software para controle de um robô móvel autônomo
(8º Simpósio Brasileiro de Automação Inteligente, 2007-10-08) Britto, Ricardo de Sousa; Medeiros, Adelardo Adelino Dantas de; Alsina, Pablo Javier
Column generation bounds for numerical microaggregation
(Springer, 2014-02-18) Rocha, Caroline Thennecy de Medeiros; Aloise, Daniel; Hansen, Pierre; Santi, Éverton
The biggest challenge when disclosing private data is to share information contained in databases while protecting people from being individually identified. Microaggregation is a family of methods for statistical disclosure control. The principle of microaggregation is that confidentiality rules permit the publication of individual records if they are partitioned into groups of size larger or equal to a fixed threshold value, where none is more representative than the others in the same group. The application of such rules leads to replacing individual values by those computed from small groups (microaggregates), before data publication. This work proposes a column generation algorithm for numerical microaggregation in which its pricing problem is solved by a specialized branch-and-bound. The algorithm is able to find, for the first time, lower bounds for instances of three real-world datasets commonly used in the literature. Furthermore, new best known solutions are obtained for these instances by means of a simple heuristic method with the columns generated
Development of an active orthosis prototype for lower limbs
(2009-11) Araújo, Márcio V.; Alsima, Pablo J.; Medeiros, Adelardo Adelino Dantas de; Pereira, Jonathan P. P.; Domingos, Elber C.; Araújo, Fábio M. U.; Silva, Jáder S.
Distributed-Memory load balancing with cyclic token-based work-stealing applied to reverse time migration
(Institute of Electrical and Electronics Engineers, 2019) Martins, Idalmis Milian Sardina; Assis, Ítalo Augusto Souza; Oliveira, Antônio D. S.; Barros, Tiago; Bianchini, Calebe P.; Souza, Samuel Xavier de
Reverse time migration (RTM) is a prominent technique in seismic imaging. Its resulting subsurface images are used in the industry to investigate with higher confidence the existence and the conditions of oil and gas reservoirs. Because of its high computational cost, RTM must make use of parallel computers. Balancing the workload distribution of an RTM is a growing challenge in distributed computing systems. The competition for shared resources and the differently-sized tasks of the RTM are some of the possible sources of load imbalance. Although many load balancing techniques exist, scaling up for large problems and large systems remains a challenge because synchronization overhead also scales. This paper proposes a cyclic token-based work-stealing (CTWS) algorithm for distributed memory systems applied to RTM. The novel cyclic token approach reduces the number of failed steals, avoids communication overhead, and simplifies the victim selection and the termination strategy. The proposed method is implemented as a C library using the one-sided communication feature of the message passing interface (MPI) standard. Results obtained by applying the proposed technique to balance the workload of a 3D RTM system present a factor of 14.1 % speedup and reductions of the load imbalance of 78.4 % when compared to the conventional static distribution
Uma ferramenta computacional par o agendamento de operações do programa de acessibilidade especial porta a porta - PRAE
(SOBRAPO, 2014) Rocha, Caroline Thennecy de Medeiros; Dantas, Saulo de Tarso Alves; Aloise, Daniel; Galvão, José Claudio; Martins, Ana Maria da Silva
Em todo o mundo, a demanda por serviços de transporte para pessoas portadoras de necessidades especiais, idosos, e pessoas com mobilidade reduzida vêm crescendo nos últimos anos. A população está envelhecendo, os governos precisam se adaptar a esta realidade, e este fato pode significar oportunidade de negócios para as companhias. Dentro deste contexto está inserido o Programa de Acessibilidade Especial porta a porta – PRAE do município de Natal-RN. A pesquisa presente neste trabalho procura desenvolver um modelo de programação capaz de auxiliar o processo de tomada de decisão dos gestores deste serviço de transporte. Para tanto, foi criado um algoritmo baseado em métodos de geração de soluções aproximativas conhecidas como heurísticas. O objetivo do modelo é incrementar o número de pessoas atendidas pelo PRAE, dada a frota disponível, gerando programações de roteiros otimizadas. O PRAE consiste em um problema de roteirização e programação de veículos do tipo dial-a-ride – DARP, um dos tipos mais complexos dentre os problemas de roteirização. A validação do método de resolução foi feita mediante a comparação entre os resultados auferidos pelo modelo computacional e a programação manual real atual. Os resultados mostraram que o modelo idealizado neste trabalho foi capaz de elevar a capacidade de atendimento deste serviço de transporte
Global optimization workshop 2012
(Springer, 2014-07-24) Rocha, Caroline Thennecy de Medeiros; Aloise, Daniel; Hansen, Pierre
The Global Optimization Workshop 2012 (GOW 2012) was the eleventh of a series of meetings, organized to be a forum for both academic and industrial communities to present and discuss the latest results and challenges in global optimization
Implementação de classificador de tarefas mentais baseado em EEG
(Sociedade Brasileira de Redes Neurais, 2009-10) Medeiros, Adelardo Adelino Dantas de; Barbosa, André Freitas; Souza, Bryan C.; Pereira Júnior, Antônio
Localization of a mobile robot based on odometry and natural landmarks using extended kalman filter
(International Conference on Informatics in Control, Automation and Robotics, 2008) Santana, Andre M.; Sousa, Anderson A. S.; Britto, Ricardo S.; Alsina, Pablo J.; Medeiros, Adelardo Adelino Dantas de
A model for clustering data from heterogeneous dissimilarities
(Elsevier, 2016-09-16) Santi, Éverton; Aloise, Daniel; Blanchard, Simon J.
Clustering algorithms partition a set of n objects into p groups (called clusters), such that objects assigned to the same groups are homogeneous according to some criteria. To derive these clusters, the data input required is often a single n × n dissimilarity matrix. Yet for many applications, more than one instance of the dissimilarity matrix is available and so to conform to model requirements, it is common practice to aggregate (e.g., sum up, average) the matrices. This aggregation practice results in clustering solutions that mask the true nature of the original data. In this paper we introduce a clustering model which, to handle the heterogeneity, uses all available dissimilarity matrices and identifies for groups of individuals clustering objects in a similar way. The model is a nonconvex problem and difficult to solve exactly, and we thus introduce a Variable Neighborhood Search heuristic to provide solutions efficiently. Computational experiments and an empirical application to perception of chocolate candy show that the heuristic algorithm is efficient and that the proposed model is suited for recovering heterogeneous data. Implications for clustering researchers are discussed
Modelagem dinâmica e simulação computacional de poços de petróleo verticais e direcionais com elevação por bombeio mecânico
(5º Congresso Brasileiro de Pesquisa e Desenvolvimento em Petróleo e Gás, 2009-10-15) Filipe, C. A. Lins; Kayo, G. SIlva; Medeiros, Adelardo Adelino Dantas de; Costa, Rutácio O.
NPi-Cluster: a Low Power Energy-Proportional Computing Cluster Architecture
(Institute of Electrical and Electronics Engineers, 2017-08-09) Filho, Sebastião Emidio Alves; Burlamaqui, Aquiles Medeiros Filgueira; Aroca, Rafael Vidal; Gonçalves, Luiz Marcos Garcia
This paper presents the NPi-Cluster, an energy proportional computing cluster that automatically powers ON or OFF the number of running machines according to the actual processing demand. A theoretical model is proposed, discussed, and implemented on a cluster composed of Raspberry Pi computer boards designed and built in order to test the proposed system architecture. Experimental results show adequate performance of the proposed platform when compared with other web servers running on traditional server architectures, but with considerably less power consumption. The power consumption of the entire cluster is about 14 W when running at maximum performance. In this situation, the system is able to handle more than 450 simultaneous requests, with about 1000 transactions per second, making it possible to be used as a server capable of handling real web workloads with acceptable quality of service. When the requests demand is reduced to a minimum, the power consumption is dynamically reduced until less than 2 W. Additionally, the proposed cluster architecture also provides high availability by reducing single points of failure on the system
Optical flow using color information: preliminary results
(23º Annual ACM Symposium on Applied Computing, 2008-03-16) Aires, Kelson R. T.; Santana, André M.; Medeiros, Adelardo Adelino Dantas de
Performance evaluation of multi-UAV network applied to scanning rocket impact area
(MDPI, 2019-11-09) Silva, Maurício R.; Souza, Elitelma S.; Alsina, Pablo Javier; Leite, Deyvid Lucas; Morais, Mateus Rodrigues de; Pereira, Diego S.; Nascimento, Luís B. P.; Medeiros, Adelardo Adelino Dantas de; Cunha Junior, Francisco H.; Nogueira, Marcelo Borges; Albuquerque, Glauberto Leilson Alves de; Dantas, João B. D.
This paper presents a communication network for a squadron of unmanned aerial vehicles (UAVs) to be used in the scanning rocket impact area for Barreira do Inferno Launch Center—CLBI (Rio Grande do Norte, Brazil), aiming at detecting intruder boats. The main features of communication networks associated with multi-UAV systems are presented. This system sends information through Wireless Sensor Networks (WSN). After comparing and analyzing area scanning strategies, it presents the specification of a data communication network architecture for a squadron of UAVs within a sensor network using XBee Pro 900HP S3B modules. A brief description is made about the initial information from the construction of the system. The embedded hardware and the design procedure of a dedicated communication antenna to the XBee modules are presented. In order to evaluate the performance of the proposed architecture in terms of robustness and reliability, a set of experimental tests in different communication scenarios is carried out. Network management software is employed to measure the throughput, packet loss and other performance indicators in the communication links between the different network nodes. Experimental results allow verifying the quality and performance of the network nodes, as well as the reliability of the communication links, assessing signal received quality, range and latency
Plane detection from monocular image sequences
(2008) Aires, Kelson R. T.; Araújo, Helder de J.; Medeiros, Adelardo Adelino Dantas de
Plane Detection Using Affine Homography
(Visualization, Imaging and Image Processing, 2008) Aires, Kelson R. T.; Araújo, Hélder J.; Medeiros, Adelardo Adelino Dantas de
Pose estimation of a humanoid robot using images from a mobile external camera
(IFAC Workshop on Multivehicle Systems, 2006) Nogueira, Marcelo Borges; Medeiros, Adelardo Adelino Dantas de; Alsina, Pablo J.
A proposal to the supervision of processes in an industrial environment with heterogeneous systems
(International Conference of the IEEE Industrial Electronics Society, 2006) Souza, Rodrigo B; Medeiros, Adelardo Adelino Dantas de; Nascimento, João M A; Gomes, Heitor P; Maitelli, André L
Uma proposta de slam com determinação de informações geométricas do ambiente
(Congresso Brasileiro de Automática, 2006) Pedrosa, Diogo P. F.; Medeiros, Adelardo Adelino Dantas de; Alsina, Pablo J.
Real-Time Visual SLAM Using Pre - Existing Floor Lines as Landmarks and a Single Camera
(Congresso Brasileiro de Automática, 2008) Macedo, Andre S.; Santiago, Gutemberg S.; Medeiros, Adelardo Adelino Dantas de

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