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Search Results: 1 - 10 of 54372 matches for " Ant?nio Fernando Branco Costa "
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O uso da estatística de qui-quadrado no controle de processos
Costa, Antnio Fernando Branco;Magalh?es, Maysa Sacramento de;
Gest?o & Produ??o , 2005, DOI: 10.1590/S0104-530X2005000200010
Abstract: it is standard practice to use joint charts in process control, one designed to detect shifts in the mean and the other to detect changes in the variance of the process. in this paper, we propose the use of a single chart to control both mean and variance. based on the noncentral chi square statistic, the single chart is faster in detecting shifts in the mean and increases in variance than its competitor, the joint "xbar" and r charts. the noncentral chi square statistic can also be used with the ewma procedure, particularly in the detection of small mean shifts, accompanied or not by slight increases in variance.
Monitoring the mean vector and the covariance -matrix of multivariate processes with sample means and sample ranges
Costa, Antnio Fernando Branco;Machado, Marcela Aparecida Guerreiro;
Produ??o , 2011, DOI: 10.1590/S0103-65132011005000029
Abstract: the joint and r charts and the joint and s2 charts are the most common charts used for monitoring the process mean and dispersion. with the usual sample sizes of 4 and 5, the joint and r charts are slightly inferior to the joint and s2 charts in terms of efficiency in detecting process shifts. in this article, we show that for the multivariate case, the charts based on the standardized sample means and sample ranges (mrmax chart) or on the standardized sample means and sample variances (mvmax chart) are similar in terms of efficiency in detecting shifts in the mean vector and/or in the covariance matrix. user's familiarity with the computation of sample ranges is a point in favor of the mrmax chart. an example is presented to illustrate the application of the proposed chart.
Monitoring the mean vector and the covariance -matrix of multivariate processes with sample means and sample ranges Monitoramento do vetor de médias e da matriz de covariancias de processos multivariados baseado nas médias e nas amplitudes amostrais
Antnio Fernando Branco Costa,Marcela Aparecida Guerreiro Machado
Produ??o , 2011,
Abstract: The joint and R charts and the joint and S2 charts are the most common charts used for monitoring the process mean and dispersion. With the usual sample sizes of 4 and 5, the joint and R charts are slightly inferior to the joint and S2 charts in terms of efficiency in detecting process shifts. In this article, we show that for the multivariate case, the charts based on the standardized sample means and sample ranges (MRMAX chart) or on the standardized sample means and sample variances (MVMAX chart) are similar in terms of efficiency in detecting shifts in the mean vector and/or in the covariance matrix. User's familiarity with the computation of sample ranges is a point in favor of the MRMAX chart. An example is presented to illustrate the application of the proposed chart. Os gráficos conjuntos de e R e e S2 s o os mais utilizados para o monitoramento da média e da dispers o do processo. Com os tamanhos de amostra usuais de 4 e 5, os gráficos de e R em uso conjunto s o ligeiramente inferior aos gráficos de e S2 em uso conjunto em termos da eficiência em detectar altera es no processo. Neste artigo, mostra-se que para o caso multivariado, os gráficos baseados nas médias amostrais padronizadas e amplitudes amostrais (gráfico MRMAX) ou nas médias amostrais padronizadas e variancias amostrais (gráfico MVMAX) s o similares em termos da eficiência em detectar altera es no vetor de médias e/ou na matriz de covariancias. A familiaridade do usuário com o cálculo de amplitudes amostrais é um aspecto favorável do gráfico MRMAX. Um exemplo é apresentado para ilustrar a aplica o do gráfico proposto.
Monitoring the Mean Vector and the Covariance Matrix of Bivariate Processes
Marcela Aparecida Guerreiro Machado,Antnio Fernando Branco Costa
Brazilian Journal of Operations & Production Management , 2010,
Abstract: This paper proposes the joint use of two charts based on the non-central chi-square statistic (NCS statistic) for monitoring the mean vector and the covariance matrix of bivariate processes, named as the joint NCS charts. The expression to compute the ARL, which is defined as the average number of samples the joint charts need to signal an out-of-control condition, is derived. The joint NCS charts might be more sensitive to changes in the mean vector or, alternatively, more sensitive to changes in the covariance matrix, accordingly to the values of their design parameters. In general, the joint NCS charts are faster than the combined T2 and |S| charts in signaling out-of-control conditions. Once the proposed scheme signals, the user can immediately identify the out-of-control variable. The risk of misidentifying the out-of-control variable is small (less than 5.0%).
Gráfico de controle MCMAX para o monitoramento simultaneo do vetor de médias e da matriz de covariancias
Costa, Antnio Fernando Branco;Machado, Marcela Aparecida Guerreiro;Claro, Fernando Antnio Elias;
Gest?o & Produ??o , 2010, DOI: 10.1590/S0104-530X2010000100012
Abstract: the control chart and the generalized variance |s| chart are used for monitoring the mean vector and the covariance matrix of multivariate processes. in this article, we propose the use of a single chart for monitoring bivariate processes, that is, the mcmax control chart based on a new statistic, which corresponds to the maximum among four sample values: the standardized sample means (in module) and the standardized sample variances (weighted). the sample means and sample variances are well known by the users; the same cannot be said for the hotelling's statistic or the generalized variance. consequently, they will prefer to use the proposed chart instead of the joint and |s| charts. in general, the user prefers to wait until the occurrence of a second point beyond the control limit (not far from the first one) before interfering in the process. with this new rule, the proposed chart is faster in signaling out-of-control conditions, except when the correlation between the two quality characteristics is too high. in this case, the joint and |s| charts are faster is signaling assignable causes that only affect one of the two quality characteristics, changing its mean and/or increasing its variance.
Gráfico de controle de VMAX para o monitoramento da matriz de covariancias
Machado, Marcela Aparecida Guerreiro;Magalh?es, Maysa Sacramento de;Costa, Antnio Fernando Branco;
Produ??o , 2008, DOI: 10.1590/S0103-65132008000200003
Abstract: in this paper a control chart based on sample variances from two quality characteristics for monitoring bivariate normal processes is proposed. the points plotted on the chart are the maximum of the values of these two statistics. the proposed chart (vmax chart) detects process disturbances faster than the generalized variance |s| chart and has a better diagnostic feature, that is, with the vmax chart it is easier to relate an out-of-control signal to the variable whose variability has moved away from its in-control state. when the double sampling scheme is used the proposed chart has also a better performance, except in a few cases in which the size of the samples at the second stage is very large.
Tempo de implanta??o de sistemas ERP: análise da influência de fatores e aplica??o de técnicas de gerenciamento de projetos
Padilha, Thais Cássia Cabral;Costa, Antnio Fernando Branco;Contador, José Luiz;Marins, Fernando Augusto Silva;
Gest?o & Produ??o , 2004, DOI: 10.1590/S0104-530X2004000100006
Abstract: usually the implementation of erp systems is very complex, and not immediate, in some cases requires three or even four years. in general, the erp system is divided in modules, and its implementation is made in stages. at each stage, a few modules are implemented. according to several authors the deadlines of modules implementation are critical, and rarely are obeyed, so such delays make the customer insatisfied because they result in additional costs for them. the implementation of erp are dictaded by several factors, some of them have more influence on its duration. the technique of design planning is considered here to determine these factors. moreover, using critical path methods are identified the bottleneck activities which require more investment in order to reduce the duration of whole project.
Pimplinae (Hymenoptera, Ichneumonidae) em um fragmento de Cerrado na Reserva Biológica Unilavras/Boqueir?o, Ingaí, Minas Gerais, Brasil
Tanque, Ricardo Lima;Frieiro-Costa, Fernando Antnio;
Biota Neotropica , 2011, DOI: 10.1590/S1676-06032011000400017
Abstract: the composition of pimplinae taxocenosis (hymenoptera, ichneumonidae) was investigated in the reserva biológica unilavras/boqueir?o, ingaí, minas gerais. samples were collected using two malaise traps (townes model), installed in a gallery forest and a savanna area between april 2005 and february 2006, totalizing 16 samples in each environment. one hundred specimens of pimplinae were collected, being represented by 26 species and distributed in 12 genera. pimpla and neotheronia were the most abundant with 65 collected specimens. in gallery forest 71 individuals were collected and in savanna, 29. this survey expands the distributional records of eruga draperi gauld, 1991; polysphincta thoracica (cresson, 1874); zaglyptus simonis (marshall, 1892), and neotheronia hespenheidei gauld, 1991 towards the cerrado domain.
Macroalgas de ambientes lóticos da regi?o centro-oeste do Paraná, regi?o sul do Brasil
Branco, Ciro Cesar Zanini;Peres, Cleto Kaveski;Krupek, Rogério Antnio;Bertusso, Fernando Rodrigo;
Biota Neotropica , 2009, DOI: 10.1590/S1676-06032009000200022
Abstract: taxonomic studies focusing on the inventory of lotic macroalgae in different regions are important contributions to the basic knowledge for these algal communities. in this context, the main objective of this investigation was to accomplish a floristic survey of the stream macroalgal communities in the mid-west region of paraná state, southern brazil, a poorly investigated subtropical area. twenty-two stream segments were sampled by means of cross-transect technique. twenty-four macroalgal taxa were found, including 18 subgeneric taxa and 6 vegetative groups. chlorophyta was the most species rich division (13 taxa = 54% of the total), followed by cyanophyta (five taxa = 21%) and rhodophyta and heterokontophyta (3 taxa = 12.5%). phormidium retzii (c. agardh) gomont (cyanophyta) was the most widespread species, and mats the predominant morphological type. although all the macroalgal taxa had been previously described from brazilian streams, 5 species are new records from paraná state. even with no additional species reported, the survey in the mid-west region of paraná state are relevant, since it expanded the geographical and environmental distribution of the stream macroalgal communities in brazil.
Shrinking Lung Detected on Computed Tomography: Pictorial Essay of the Main Findings of the Image  [PDF]
Francisco Barbosa de Araújo Neto, Tiago Castello Branco Lyra, Rita Karine Veras Gomes de Mello, Vinícius Martins Valois, Tiago Bezerra Albano, Antnio Fernando Lins de Paiva, Rodrigo Caruso Chate, Cesar Higar Nomura
Open Journal of Medical Imaging (OJMI) , 2018, DOI: 10.4236/ojmi.2018.82003
Abstract:

Shrinking lung refers to a rare complication of systemic lupus erythematosus and is characterized by unexplained dyspnea, a restrictive pattern in lung function tests, and elevation of the diaphragmatic hemicuples. It is postulated to have a predilection for female involvement and occurs mainly during late stages of the disease. Chest X-rays usually show small, diaphragmatic lungs. Occasional basal atelectasis may be present. Chest tomography usually shows reduced lung volumes with diaphragmatic elevation, occasional basal atelectasis, without severe pulmonary or pleuropulmonary disease. Shrinking lung can cause significant morbidity and occasional mortality. There is no definitive therapy, while corticosteroids may decrease symptoms and improve lung function in some patients. The objective of this study was to describe the main imaging findings in Shrinking Lung, an important pulmonary alteration in lupus patients. We highlight the characteristics observed on radiography and computed tomography, with an emphasis on computed tomography. It is important that every radiologist is prepared to recognize these findings and understand the possible clinical repercussions.

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