1000 resultados para Processos estocàstics -- Models matemàtics
Resumo:
This work proposes a modified control chart incorporating concepts of time series analysis. Specifically, we considerer Gaussian mixed transition distribution (GMTD) models. The GMTD models are a more general class than the autorregressive (AR) family, in the sense that the autocorrelated processes may present flat stretches, bursts or outliers. In this scenario traditional Shewhart charts are no longer appropriate tools to monitoring such processes. Therefore, Vasilopoulos and Stamboulis (1978) proposed a modified version of those charts, considering proper control limits based on autocorrelated processes. In order to evaluate the efficiency of the proposed technique a comparison with a traditional Shewhart chart (which ignores the autocorrelation structure of the process), a AR(1) Shewhart control chart and a GMTD Shewhart control chart was made. An analytical expression for the process variance, as well as control limits were developed for a particular GMTD model. The ARL was used as a criteria to measure the efficiency of control charts. The comparison was made based on a series generated according to a GMTD model. The results point to the direction that the modified Shewhart GMTD charts have a better performance than the AR(1) Shewhart and the traditional Shewhart.
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The new management models have led to the reorganization of institutions today. Much is made in improving the delivery of public services entities, and they have sought to adopt these new initiatives in order to improve the quality of the product or service offered to users. The modernization of the management model at the Federal University of Rio Grande do Norte (UFRN) strengthened by the accession of the institution to GesPública Program, which focuses on the management modernization leading institutions to seek ways to fit to meet the demands proposed the Program. Therefore, the Department of Personnel Administration (DAP) has structured its processes and procedures using the mapping tool processes. This research starts from the question: what were the results obtained with the implementation of the management and process mapping of PAD? It is proposed as a general objective to analyze the management and the mapping of that Board processes, identifying the possible benefits in improving the quality of the services provided to users. The specific objectives to achieve results, are pointed out: describe how you carried out the implementation of the management and process mapping in DAP and how it is working at the moment; examine the line in the relationship between the actions developed by the DAP and modern theories of this theme; identify the evolution of the sector with the measures adopted and the results obtained with the implementation of the mapping tool. In the theoretical framework, it was approached a brief history of the evolution of public administration in Brazil, GesPública program and its importance for process management in public institutions as well as the Management and Process Mapping. The context of the study was the DAP, and participants were managers of the institution in the survey. Data collection was done through the study of the institution's documents, bibliography analysis available on the topic, questionnaires and semi-structured interviews with professionals of the institution involved with the object of study, since its inception until July 2015, when it was finished the search. As a result, were listed: the motivation, importance, benefits and innovations that management and the mapping of processes brought to the institution, point out what has been improved in the service users and the tools used. We also analyze the main problems identified during the implementation of the mapping. As a suggestion, it was analyzed how these procedures can, if possible, be extended to other sectors of UFRN.
Resumo:
The new management models have led to the reorganization of institutions today. Much is made in improving the delivery of public services entities, and they have sought to adopt these new initiatives in order to improve the quality of the product or service offered to users. The modernization of the management model at the Federal University of Rio Grande do Norte (UFRN) strengthened by the accession of the institution to GesPública Program, which focuses on the management modernization leading institutions to seek ways to fit to meet the demands proposed the Program. Therefore, the Department of Personnel Administration (DAP) has structured its processes and procedures using the mapping tool processes. This research starts from the question: what were the results obtained with the implementation of the management and process mapping of PAD? It is proposed as a general objective to analyze the management and the mapping of that Board processes, identifying the possible benefits in improving the quality of the services provided to users. The specific objectives to achieve results, are pointed out: describe how you carried out the implementation of the management and process mapping in DAP and how it is working at the moment; examine the line in the relationship between the actions developed by the DAP and modern theories of this theme; identify the evolution of the sector with the measures adopted and the results obtained with the implementation of the mapping tool. In the theoretical framework, it was approached a brief history of the evolution of public administration in Brazil, GesPública program and its importance for process management in public institutions as well as the Management and Process Mapping. The context of the study was the DAP, and participants were managers of the institution in the survey. Data collection was done through the study of the institution's documents, bibliography analysis available on the topic, questionnaires and semi-structured interviews with professionals of the institution involved with the object of study, since its inception until July 2015, when it was finished the search. As a result, were listed: the motivation, importance, benefits and innovations that management and the mapping of processes brought to the institution, point out what has been improved in the service users and the tools used. We also analyze the main problems identified during the implementation of the mapping. As a suggestion, it was analyzed how these procedures can, if possible, be extended to other sectors of UFRN.
Resumo:
Tese submetida à Universidade de Lisboa, Instituto Superior Técnico e aprovada em provas públicas para a obtenção do Grau de Doutor em Sistemas Sustentáveis de Energia.
Resumo:
Dissertação de Mestrado, Oncobiologia: Mecanismos Moleculares do Cancro, Departamento de Ciências Biomédicas e Medicina, Universidade do Algarve, 2015
Resumo:
The oscillations presents in control loops can cause damages in petrochemical industry. Canceling, or even preventing such oscillations, would save up to large amount of dollars. Studies have identified that one of the causes of these oscillations are the nonlinearities present on industrial process actuators. This study has the objective to develop a methodology for removal of the harmful effects of nonlinearities. Will be proposed an parameter estimation method to Hammerstein model, whose nonlinearity is represented by dead-zone or backlash. The estimated parameters will be used to construct inverse models of compensation. A simulated level system was used as a test platform. The valve that controls inflow has a nonlinearity. Results and describing function analysis show an improvement on system response
Resumo:
Dissertação (mestrado)—Universidade de Brasília, Faculdade UnB Planaltina, Programa de Pós-Graduação em Gestão Pública, Mestrado Profissional em Gestão Pública, 2016.
Resumo:
Prosopis rubriflora and Prosopis ruscifolia are important species in the Chaquenian regions of Brazil. Because of the restriction and frequency of their physiognomy, they are excellent models for conservation genetics studies. The use of microsatellite markers (Simple Sequence Repeats, SSRs) has become increasingly important in recent years and has proven to be a powerful tool for both ecological and molecular studies. In this study, we present the development and characterization of 10 new markers for P. rubriflora and 13 new markers for P. ruscifolia. The genotyping was performed using 40 P. rubriflora samples and 48 P. ruscifolia samples from the Chaquenian remnants in Brazil. The polymorphism information content (PIC) of the P. rubriflora markers ranged from 0.073 to 0.791, and no null alleles or deviation from Hardy-Weinberg equilibrium (HW) were detected. The PIC values for the P. ruscifolia markers ranged from 0.289 to 0.883, but a departure from HW and null alleles were detected for certain loci; however, this departure may have resulted from anthropic activities, such as the presence of livestock, which is very common in the remnant areas. In this study, we describe novel SSR polymorphic markers that may be helpful in future genetic studies of P. rubriflora and P. ruscifolia.
Resumo:
In acquired immunodeficiency syndrome (AIDS) studies it is quite common to observe viral load measurements collected irregularly over time. Moreover, these measurements can be subjected to some upper and/or lower detection limits depending on the quantification assays. A complication arises when these continuous repeated measures have a heavy-tailed behavior. For such data structures, we propose a robust structure for a censored linear model based on the multivariate Student's t-distribution. To compensate for the autocorrelation existing among irregularly observed measures, a damped exponential correlation structure is employed. An efficient expectation maximization type algorithm is developed for computing the maximum likelihood estimates, obtaining as a by-product the standard errors of the fixed effects and the log-likelihood function. The proposed algorithm uses closed-form expressions at the E-step that rely on formulas for the mean and variance of a truncated multivariate Student's t-distribution. The methodology is illustrated through an application to an Human Immunodeficiency Virus-AIDS (HIV-AIDS) study and several simulation studies.
Resumo:
Often in biomedical research, we deal with continuous (clustered) proportion responses ranging between zero and one quantifying the disease status of the cluster units. Interestingly, the study population might also consist of relatively disease-free as well as highly diseased subjects, contributing to proportion values in the interval [0, 1]. Regression on a variety of parametric densities with support lying in (0, 1), such as beta regression, can assess important covariate effects. However, they are deemed inappropriate due to the presence of zeros and/or ones. To evade this, we introduce a class of general proportion density, and further augment the probabilities of zero and one to this general proportion density, controlling for the clustering. Our approach is Bayesian and presents a computationally convenient framework amenable to available freeware. Bayesian case-deletion influence diagnostics based on q-divergence measures are automatic from the Markov chain Monte Carlo output. The methodology is illustrated using both simulation studies and application to a real dataset from a clinical periodontology study.
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Process Analytical Chemistry (PAC) is an important and growing area in analytical chemistry, that has received little attention in academic centers devoted to the gathering of knowledge and to optimization of chemical processes. PAC is an area devoted to optimization and knowledge acquisition of chemical processes, to reducing costs and wastes and to making an important contribution to sustainable development. The main aim of this review is to present to the Brazilian community the development and state of the art of PAC, discussing concepts, analytical techniques currently employed in the industry and some applications.
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Glutathione (GSH) and related enzymes are pivotal for the normal functioning of several important biological processes. In this review we discuss the biosynthesis and the catalytic cycles of glutathione as well as the major GSH-related enzymes. We also present how glutathione and enzymes are involved in cancer and the chromatographic and non-chromatographic methods used to analyze glutathione and/or its derivatives.
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Petroleum biodegradation in reservoirs is a process caused by different microorganisms affecting many oil deposits which modifies the oil composition in a quasi-stepwise process starting from n-alkanes and isoprenoids through to diasteranes. This causes oil souring and increased viscosity, sulfur and metal content, having a direct impact on oil production and refining costs.
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Arrabidaea chica (H&B) Verlot is a plant popularly known as Pariri and this species is a known source of anthocyanins, flavonoids and tannins. This report describes an approach involving enzymatic treatment prior to extraction procedures to enhance A chica crude extract anticancer activity. Anticancer activity in human cancer cell lines in vitro using a 48 h SRB cell viability assay was performed to determine growth inhibition and cytotoxic properties. The final extraction yield without enzyme treatment was higher (24.28%) compared to the enzyme-treated material (19.03%), with an enhanced aglycones anthocyanin ratio as determined by HPLC- DAD and LC-MS with direct infusion.