Joao Maupelo da Costa - Academia.edu (original) (raw)

Uploads

Papers by Joao Maupelo da Costa

Research paper thumbnail of Statistical Audit via Gaussian Mixture Models in Business Intelligence Systems

Anais do Simpósio Brasileiro de Sistemas de Informação (SBSI), 2015

A Business Intelligence (BI) System employs tools from several areas of knowledge for the collect... more A Business Intelligence (BI) System employs tools from several areas of knowledge for the collection, integration and analysis of data to improve business decision making. The Brazilian Ministry of Planning, Budget and Management (MP) uses a BI System designed with the University of Brasília to ascertain irregularities on the payroll of the Brazilian federal government, performing audit trails on selected items and fields of the payroll database. This current auditing approach is entirely deterministic, since the audit trails look for previously known signatures of irregularities which are composed by means of an ontological method used to represent auditors concept maps. In this work, we propose to incorporate a statistical filter in this existing BI system in order to increase its performance in terms of processing speed and overall system responsiveness. The proposed statistical filter is based on a generative Gaussian Mixture Model (GMM) whose goal is to provide a complete stoch...

Research paper thumbnail of A Parallel Approach to PCA Based Malicious Activity Detection in Distributed Honeypot Data

The International Journal of Forensic Computer Science, 2011

Model order selection (MOS) schemes, which are frequently employed in several signal processing a... more Model order selection (MOS) schemes, which are frequently employed in several signal processing applications, are shown to be effective tools for the detection of malicious activities in honeypot data. In this paper, we extend previous results by proposing an efficient and parallel MOS method for blind automatic malicious activity detection in distributed honeypots. Our proposed scheme does not require any previous information on attacks or human intervention. We model network traffic data as signals and noise and then apply modified signal processing methods. However, differently from the previous centralized solutions, we propose that the data colected by each honeypot node be processed by nodes in a cluster (that may consist of the collection nodes themselves) and then grouped to obtain the final results. This is achieved by having each node locally compute the Eigenvalue Decomposition (EVD) to its own sample correlation matrix (obtained from the honeypot data) and transmit the resulting eigenvalues to a central node, where the global eigenvalues and final model order are computed. The model order computed from the global eigenvalues through RADOI represents the number of malicious activities detected in the analysed data. The feasibility of the proposed approach is demonstrated through simulation experiments. (6)

Research paper thumbnail of Blind Joint Channel Estimation and Data Detection for Precoded Multi-Layered Space-Frequency MIMO Schemes

Circuits, Systems, and Signal Processing, 2013

Due to the scarcity of the electromagnetic spectrum, multidimensional signaling schemes that take... more Due to the scarcity of the electromagnetic spectrum, multidimensional signaling schemes that take into account several signal dimensions such as space, time, frequency and constellation, are good candidates for increasing the data rate and/or improving the link reliability in future communication systems. This work addresses the problem of joint channel estimation and data detection in precoded multi-layered space-frequency codes (MLSFC) in multiple input multiple output (MIMO) systems based on orthogonal frequency division multiplexing (OFDM). First, we consider a modified (precoded) MLSFC transmit structure that consists in extending the constellation rotation across multiple OFDM symbols. By recasting the received signal as trilinear model, we propose a low-complexity blind receiver based on the least squares Khatri-Rao factorization (LSKRF). Our proposed LSKRF receiver is a closed-form solution and it outperforms the classical alternating least squares (ALS) receiver while being less complex since no iteration is need. Our results attest to the benefits of the proposed receiver in a variety of MLSFC schemes in comparison with the non-blind zero-forcing-based MLSFC receiver that assumes perfect channel knowledge.

Research paper thumbnail of Clinical and epidemiological findings and response to treatment of 25 cases of tetanus in horses occurred in Norte Fluminense, Rio de Janeiro, Brazil

Revista Brasileira De Medicina Veterinaria, 2016

Research paper thumbnail of High performance perovskite hollow fibres for oxygen separation

Journal of Membrane Science, 2011

Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3−ı (BSCF) hollow fibres are very attractive to deliver high oxygen... more Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3−ı (BSCF) hollow fibres are very attractive to deliver high oxygen fluxes at low manufacturing costs. These membranes efficiently separate oxygen from air via ionic diffusion, and have been exclusively prepared with sulphur containing binders, a vital ingredient to aggregate ceramic particles to shape hollow fibre geometries. Here we show that the choice of binder influences the stoichiometry of the crystal structure with the formation of non-ionic conduction domains, ultimately affecting oxygen ionic diffusion. Our synthesis method used sulphur free binders for the preparation of BSCF hollow fibres, resulting in an oxygen flux increase of 105% to 9.5 ml min −1 cm −2 at 950 • C. In addition, catalytic surface modification of the BSCF hollow fibres further increased oxygen fluxes to 14.5 ml min −1 cm −2. More importantly, oxygen fluxes significantly increased by a factor of 10 below 700 • C, thus reducing operating temperature requirements by 250 • C.

Research paper thumbnail of Fidelização De Doadores De Sangue: Desafios Em Busca Da Qualidade

11O Congresso Internacional Da Rede Unida, Apr 30, 2014

Introducao: Na historia da humanidade, o sangue sempre foi um elemento conceituado e associado a ... more Introducao: Na historia da humanidade, o sangue sempre foi um elemento conceituado e associado a vida, fazendo parte do patrimonio do inconsciente coletivo, tendo em vista a grande variedade de mitos, simbolos, estigmas e preconceitos em todas as culturas. O sangue, para ser transfundido com a intencao de salvar vidas, e necessario a presenca de um doador que, enquanto elemento primordial para efetivacao desta terapeutica. Para tanto, observa-se uma quantidade insuficientes de contingente efetivo, principalmente os voluntarios e altruistas. Na pratica hemoterapica exigem-se produtos de excelencia e quantidades suficientes. A captacao de doadores deve seguir os principios da universalidade, integralidade e equidade no âmbito do Sistema Unico de Saude (SUS), e que atendam a demanda de cada servico baseando-se em dados cientificos, do contrario, ocorrera desperdicio, elevando os custos e prejudicando a assistencia. Objetivo: identificar estrategias para captacao e fidelizacao de doadores de sangue, segundo a literatura nacional. Metodologia: revisao integrativa realizada na base de dados da Biblioteca Virtual da Saude (BVS), que envolve as bases LILACS, SciELO, BDENF, DESASTRES e MEDCARIB, utilizando como descritores: “servico de hemoterapia”, “seguranca do sangue” e “doadores de sangue”. Para a selecao dos artigos foram adotados os seguintes criterios: estudos disponiveis em formato completo, nos idiomas ingles, espanhol e portugues, publicados no periodo de 2008 a 2013. Resultados: foram selecionados 92 artigos; destes, 95% apresentam pesquisas relacionadas com as atividades realizadas nas unidades hemoterapicas, como avaliacoes dos perfis epidemiologicos, fatores associados a aptidao e inaptidao e resultados sorologicos. Os outros 5% apresentam estudos com estrategias para fidelizacao dos doadores de sangue como conscientizacao, acolhimento e educacao. Conclusao: observam-se poucos estudos relacionados diretamente a estrategias para a fidelizacao de doadores de sangue, ficando esta tarefa quase que voltada exclusivamente aos servicos de hemoterapias com ajuda do Ministerio da Saude com publicacoes relacionadas a esta area.

Research paper thumbnail of Statistical Audit via Gaussian Mixture Models in Business Intelligence Systems

Anais do Simpósio Brasileiro de Sistemas de Informação (SBSI), 2015

A Business Intelligence (BI) System employs tools from several areas of knowledge for the collect... more A Business Intelligence (BI) System employs tools from several areas of knowledge for the collection, integration and analysis of data to improve business decision making. The Brazilian Ministry of Planning, Budget and Management (MP) uses a BI System designed with the University of Brasília to ascertain irregularities on the payroll of the Brazilian federal government, performing audit trails on selected items and fields of the payroll database. This current auditing approach is entirely deterministic, since the audit trails look for previously known signatures of irregularities which are composed by means of an ontological method used to represent auditors concept maps. In this work, we propose to incorporate a statistical filter in this existing BI system in order to increase its performance in terms of processing speed and overall system responsiveness. The proposed statistical filter is based on a generative Gaussian Mixture Model (GMM) whose goal is to provide a complete stoch...

Research paper thumbnail of A Parallel Approach to PCA Based Malicious Activity Detection in Distributed Honeypot Data

The International Journal of Forensic Computer Science, 2011

Model order selection (MOS) schemes, which are frequently employed in several signal processing a... more Model order selection (MOS) schemes, which are frequently employed in several signal processing applications, are shown to be effective tools for the detection of malicious activities in honeypot data. In this paper, we extend previous results by proposing an efficient and parallel MOS method for blind automatic malicious activity detection in distributed honeypots. Our proposed scheme does not require any previous information on attacks or human intervention. We model network traffic data as signals and noise and then apply modified signal processing methods. However, differently from the previous centralized solutions, we propose that the data colected by each honeypot node be processed by nodes in a cluster (that may consist of the collection nodes themselves) and then grouped to obtain the final results. This is achieved by having each node locally compute the Eigenvalue Decomposition (EVD) to its own sample correlation matrix (obtained from the honeypot data) and transmit the resulting eigenvalues to a central node, where the global eigenvalues and final model order are computed. The model order computed from the global eigenvalues through RADOI represents the number of malicious activities detected in the analysed data. The feasibility of the proposed approach is demonstrated through simulation experiments. (6)

Research paper thumbnail of Blind Joint Channel Estimation and Data Detection for Precoded Multi-Layered Space-Frequency MIMO Schemes

Circuits, Systems, and Signal Processing, 2013

Due to the scarcity of the electromagnetic spectrum, multidimensional signaling schemes that take... more Due to the scarcity of the electromagnetic spectrum, multidimensional signaling schemes that take into account several signal dimensions such as space, time, frequency and constellation, are good candidates for increasing the data rate and/or improving the link reliability in future communication systems. This work addresses the problem of joint channel estimation and data detection in precoded multi-layered space-frequency codes (MLSFC) in multiple input multiple output (MIMO) systems based on orthogonal frequency division multiplexing (OFDM). First, we consider a modified (precoded) MLSFC transmit structure that consists in extending the constellation rotation across multiple OFDM symbols. By recasting the received signal as trilinear model, we propose a low-complexity blind receiver based on the least squares Khatri-Rao factorization (LSKRF). Our proposed LSKRF receiver is a closed-form solution and it outperforms the classical alternating least squares (ALS) receiver while being less complex since no iteration is need. Our results attest to the benefits of the proposed receiver in a variety of MLSFC schemes in comparison with the non-blind zero-forcing-based MLSFC receiver that assumes perfect channel knowledge.

Research paper thumbnail of Clinical and epidemiological findings and response to treatment of 25 cases of tetanus in horses occurred in Norte Fluminense, Rio de Janeiro, Brazil

Revista Brasileira De Medicina Veterinaria, 2016

Research paper thumbnail of High performance perovskite hollow fibres for oxygen separation

Journal of Membrane Science, 2011

Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3−ı (BSCF) hollow fibres are very attractive to deliver high oxygen... more Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3−ı (BSCF) hollow fibres are very attractive to deliver high oxygen fluxes at low manufacturing costs. These membranes efficiently separate oxygen from air via ionic diffusion, and have been exclusively prepared with sulphur containing binders, a vital ingredient to aggregate ceramic particles to shape hollow fibre geometries. Here we show that the choice of binder influences the stoichiometry of the crystal structure with the formation of non-ionic conduction domains, ultimately affecting oxygen ionic diffusion. Our synthesis method used sulphur free binders for the preparation of BSCF hollow fibres, resulting in an oxygen flux increase of 105% to 9.5 ml min −1 cm −2 at 950 • C. In addition, catalytic surface modification of the BSCF hollow fibres further increased oxygen fluxes to 14.5 ml min −1 cm −2. More importantly, oxygen fluxes significantly increased by a factor of 10 below 700 • C, thus reducing operating temperature requirements by 250 • C.

Research paper thumbnail of Fidelização De Doadores De Sangue: Desafios Em Busca Da Qualidade

11O Congresso Internacional Da Rede Unida, Apr 30, 2014

Introducao: Na historia da humanidade, o sangue sempre foi um elemento conceituado e associado a ... more Introducao: Na historia da humanidade, o sangue sempre foi um elemento conceituado e associado a vida, fazendo parte do patrimonio do inconsciente coletivo, tendo em vista a grande variedade de mitos, simbolos, estigmas e preconceitos em todas as culturas. O sangue, para ser transfundido com a intencao de salvar vidas, e necessario a presenca de um doador que, enquanto elemento primordial para efetivacao desta terapeutica. Para tanto, observa-se uma quantidade insuficientes de contingente efetivo, principalmente os voluntarios e altruistas. Na pratica hemoterapica exigem-se produtos de excelencia e quantidades suficientes. A captacao de doadores deve seguir os principios da universalidade, integralidade e equidade no âmbito do Sistema Unico de Saude (SUS), e que atendam a demanda de cada servico baseando-se em dados cientificos, do contrario, ocorrera desperdicio, elevando os custos e prejudicando a assistencia. Objetivo: identificar estrategias para captacao e fidelizacao de doadores de sangue, segundo a literatura nacional. Metodologia: revisao integrativa realizada na base de dados da Biblioteca Virtual da Saude (BVS), que envolve as bases LILACS, SciELO, BDENF, DESASTRES e MEDCARIB, utilizando como descritores: “servico de hemoterapia”, “seguranca do sangue” e “doadores de sangue”. Para a selecao dos artigos foram adotados os seguintes criterios: estudos disponiveis em formato completo, nos idiomas ingles, espanhol e portugues, publicados no periodo de 2008 a 2013. Resultados: foram selecionados 92 artigos; destes, 95% apresentam pesquisas relacionadas com as atividades realizadas nas unidades hemoterapicas, como avaliacoes dos perfis epidemiologicos, fatores associados a aptidao e inaptidao e resultados sorologicos. Os outros 5% apresentam estudos com estrategias para fidelizacao dos doadores de sangue como conscientizacao, acolhimento e educacao. Conclusao: observam-se poucos estudos relacionados diretamente a estrategias para a fidelizacao de doadores de sangue, ficando esta tarefa quase que voltada exclusivamente aos servicos de hemoterapias com ajuda do Ministerio da Saude com publicacoes relacionadas a esta area.