Análise de velocidade por otimização do semblance na reflexão sísmica

Este trabalho teve como objetivo geral desenvolver uma metodologia sistemática para a inversão de dados de reflexão sísmica em arranjo ponto-médio-comum (PMC), partindo do caso 1D de variação vertical de velocidade e espessura que permite a obtenção de modelos de velocidades intervalares, v_int,n, as espessuras intervalares, z_n, e as velocidades média-quadrática, v_RMS,n, em seções PMC individualizadas. Uma consequência disso é a transformação direta destes valores do tempo para profundidade. Como contribuição a análise de velocidade, foram desenvolvidos dois métodos para atacar o problema baseado na estimativa de velocidade intervalar. O primeiro método foi baseado na marcação manual em seções PMC, e inversão por ajuste de curvas no sentido dos quadrados-mínimos. O segundo método foi baseado na otimização da função semblance para se obter uma marcação automática. A metodologia combinou dois tipos de otimização: um Método Global (Método Price ou Simplex), e um Método Local (Gradiente de Segunda Ordem ou Conjugado), submetidos a informação à priori e vínculos. A marcação de eventos na seção tempo-distância faz parte dos processos de inversão, e os pontos marcados constituem os dados de entrada juntamente com as informações à priori do modelo a ser ajustado. A marcação deve, por princípio, evitar eventos que representem múltiplas, difrações e interseções, e numa seção pode ser feita mais de 50 marcações de eventos, enquanto que num mapa semblance não se consegue marcar mais de 10 eventos de reflexão. A aplicação deste trabalho é voltada a dados sísmicos de bacias sedimentares em ambientes marinhos para se obter uma distribuição de velocidades para a subsuperfície, onde o modelo plano-horizontal é aplicado em seções PMC individualizadas, e cuja solução pode ser usada como um modelo inicial em processos posteriores. Os dados reais da Bacia Marinha usados neste trabalho foram levantados pela PETROBRAS em 1985, e a linha sísmica selecionada foi a de número L5519 da Bacia do Camamu, e o PMC apresentado é a de número 237. A linha é composta de 1098 pontos de tiro, com arranjo unilateraldireito. O intervalo de amostragem é 4 ms. O espaçamento entre os geofones é 13,34 m com o primeiro geofone localizado a 300 m da fonte. O espaçamento entre as fontes é de 26,68 m. Como conclusão geral, o método de estimativa de velocidade intervalar apresentada neste trabalho fica como suporte alternativo ao processo de análise de velocidades, onde se faz necessário um controle sobre a sequência de inversão dos PMCs ao longo da linha sísmica para que a solução possa ser usada como modelo inicial ao imageamento, e posterior inversão tomográfica. Como etapas futuras, podemos propor trabalhos voltados direto e especificamente a análise de velocidade sísmica estendendo o caso 2D de otimização do semblance ao caso 3D, estender o presente estudo para o caso baseado na teoria do raio imagem com a finalidade de produzir um mapa continuo de velocidades para toda a seção sísmica de forma automática.

Gráficos de controle para monitoramento de processos multivariados

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Influence of the sample area in the variability of losses in the mechanical harvesting of soybeans

The mechanical harvesting is an important stage in the production process of soybeans and, in this process; the loss of a significant number of grains is common. Despite the existence of mechanisms to monitor these losses, it is still essential to use sampling methods to quantify them. Assuming that the size of the sample area affects the reliability and variability between samples in quantifying losses, this paper aimed to analyze the variability and feasibility of using different sizes of sample area (1, 2 and 3 m²) in quantifying losses in the mechanical harvesting of soybeans. Were sampled 36 sites and the cutting losses, losses by other mechanisms of the combine and total losses were evaluated, as well as the water content in seeds, straw distribution and crop productivity. Data were subjected to statistical analysis (descriptive statistics and analysis of variance) and Statistical Control Process (SCP). The coefficients of variation were similar for the three frames available. Combine losses showed stable behavior, whereas cutting losses and total losses showed unstable behavior. The frame size did not affect the quantification and variability of losses in the mechanical harvesting of soybeans, thus a frame of 1 m² can be used for determining losses.

A Single Statistic for Monitoring the Covariance Matrix of Bivariate Processes

In this article, we present a new control chart for monitoring the covariance matrix in a bivariate process. In this method, n observations of the two variables were considered as if they came from a single variable (as a sample of 2n observations), and a sample variance was calculated. This statistic was used to build a new control chart specifically as a VMIX chart. The performance of the new control chart was compared with its main competitors: the generalized sampled variance chart, the likelihood ratio test, Nagao's test, probability integral transformation (v(t)), and the recently proposed VMAX chart. Among these statistics, only the VMAX chart was competitive with the VMIX chart. For shifts in both variances, the VMIX chart outperformed VMAX; however, VMAX showed better performance for large shifts (higher than 10%) in one variance.

An analysis of Taguchi's on-line quality monitoring procedure for variables based on the results of a sequence of inspections

In this paper, a procedure for the on-line process control of variables is proposed. This procedure consists of inspecting the m-th item from every m produced items and deciding, at each inspection, whether the process is out-of-control. Two sets of limits, warning (µ0 ± W) and control (µ0 ± C), are used. If the value of the monitored statistic falls beyond the control limits or if a sequence of h observations falls between the warning limits and the control limits, the production is stopped for adjustment; otherwise, production goes on. The properties of an ergodic Markov chain are used to obtain an expression for the average cost per item. The parameters (the sampling interval m, the widths of the warning, the control limits W and C(W < C), and the sequence length (h) are optimized by minimizing the cost function. A numerical example illustrates the proposed procedure.

Quality Control in the Healthcare Industry: An Analysis of Surgery Turnover Times

For virtually all hospitals, utilization rates are a critical managerial indicator of efficiency and are determined in part by turnover time. Turnover time is defined as the time elapsed between surgeries, during which the operating room is cleaned and preparedfor the next surgery. Lengthier turnover times result in lower utilization rates, thereby hindering hospitals’ ability to maximize the numbers of patients that can be attended to. In this thesis, we analyze operating room data from a two year period provided byEvangelical Community Hospital in Lewisburg, Pennsylvania, to understand the variability of the turnover process. From the recorded data provided, we derive our best estimation of turnover time. Recognizing the importance of being able to properly modelturnover times in order to improve the accuracy of scheduling, we seek to fit distributions to the set of turnover times. We find that log-normal and log-logistic distributions are well-suited to turnover times, although further research must validate this finding. Wepropose that the choice of distribution depends on the hospital and, as a result, a hospital must choose whether to use the log-normal or the log-logistic distribution. Next, we use statistical tests to identify variables that may potentially influence turnover time. We find that there does not appear to be a correlation between surgerytime and turnover time across doctors. However, there are statistically significant differences between the mean turnover times across doctors. The final component of our research entails analyzing and explaining the benefits of introducing control charts as a quality control mechanism for monitoring turnover times in hospitals. Although widely instituted in other industries, control charts are notwidely adopted in healthcare environments, despite their potential benefits. A major component of our work is the development of control charts to monitor the stability of turnover times. These charts can be easily instituted in hospitals to reduce the variabilityof turnover times. Overall, our analysis uses operations research techniques to analyze turnover times and identify manners for improvement in lowering the mean turnover time and thevariability in turnover times. We provide valuable insight into a component of the surgery process that has received little attention, but can significantly affect utilization rates in hospitals. Most critically, an ability to more accurately predict turnover timesand a better understanding of the sources of variability can result in improved scheduling and heightened hospital staff and patient satisfaction. We hope that our findings can apply to many other hospital settings.

Smooth Hazard Function Estimation for Interval Censored Data with Time Varying Covariates

In this paper we propose methods for smooth hazard estimation of a time variable where that variable is interval censored. These methods allow one to model the transformed hazard in terms of either smooth (smoothing splines) or linear functions of time and other relevant time varying predictor variables. We illustrate the use of this method on a dataset of hemophiliacs where the outcome, time to seroconversion for HIV, is interval censored and left-truncated.

Control estadístico de calidad en bibliotecología : Aplicación de gráficos de control en los procesos técnicos

A partir de la aceptación de la biblioteca como parte del ciclo de creación, organización y diseminación del conocimiento cambió el concepto de la misma de una entidad cerrada hacia un sistema dinámico en constante interacción con su entorno. Así se la reconoció como una institución social más que como una colección de documentos. Desde entonces se percibió a la biblioteca como una entidad en la que se podía aplicar los principios de gestión. Desde entonces se utilizaron distintas herramientas de gestión para la toma de decisiones en el ámbito de las bibliotecas. Entre estas herramientas son de gran importancia en el control estadístico de procesos los gráficos de control, utilizados para medir la estabilidad de un proceso a través del tiempo. Han tenido amplia aplicación en el control estadístico de la calidad, comenzando en el ámbito industrial. Hoy su aplicación se ha extendido a una gran variedad de disciplinas incluyen empresas de servicios y unidades administrativas. Aquí se presentan a los gráficos de control como una importante herramienta de gestión aplicada a los procesos técnicos permitiendo su evaluación y el monitoreo de su desempeño a partir de la utilización de indicadores y otros datos de carácter diagnóstico

Control estadístico de calidad en bibliotecología : Aplicación de gráficos de control en los procesos técnicos

A partir de la aceptación de la biblioteca como parte del ciclo de creación, organización y diseminación del conocimiento cambió el concepto de la misma de una entidad cerrada hacia un sistema dinámico en constante interacción con su entorno. Así se la reconoció como una institución social más que como una colección de documentos. Desde entonces se percibió a la biblioteca como una entidad en la que se podía aplicar los principios de gestión. Desde entonces se utilizaron distintas herramientas de gestión para la toma de decisiones en el ámbito de las bibliotecas. Entre estas herramientas son de gran importancia en el control estadístico de procesos los gráficos de control, utilizados para medir la estabilidad de un proceso a través del tiempo. Han tenido amplia aplicación en el control estadístico de la calidad, comenzando en el ámbito industrial. Hoy su aplicación se ha extendido a una gran variedad de disciplinas incluyen empresas de servicios y unidades administrativas. Aquí se presentan a los gráficos de control como una importante herramienta de gestión aplicada a los procesos técnicos permitiendo su evaluación y el monitoreo de su desempeño a partir de la utilización de indicadores y otros datos de carácter diagnóstico

Control estadístico de calidad en bibliotecología : Aplicación de gráficos de control en los procesos técnicos

A partir de la aceptación de la biblioteca como parte del ciclo de creación, organización y diseminación del conocimiento cambió el concepto de la misma de una entidad cerrada hacia un sistema dinámico en constante interacción con su entorno. Así se la reconoció como una institución social más que como una colección de documentos. Desde entonces se percibió a la biblioteca como una entidad en la que se podía aplicar los principios de gestión. Desde entonces se utilizaron distintas herramientas de gestión para la toma de decisiones en el ámbito de las bibliotecas. Entre estas herramientas son de gran importancia en el control estadístico de procesos los gráficos de control, utilizados para medir la estabilidad de un proceso a través del tiempo. Han tenido amplia aplicación en el control estadístico de la calidad, comenzando en el ámbito industrial. Hoy su aplicación se ha extendido a una gran variedad de disciplinas incluyen empresas de servicios y unidades administrativas. Aquí se presentan a los gráficos de control como una importante herramienta de gestión aplicada a los procesos técnicos permitiendo su evaluación y el monitoreo de su desempeño a partir de la utilización de indicadores y otros datos de carácter diagnóstico

High resolution color reflectance and hematite and goethite record of ODP Hole 184-1143A in the South China Sea

Precipitation has a larger variability than temperature in tropical monsoon regions, thus it is an important climate variable. However, reconstructions of long-term rainfall histories are scarce because of the lack of reliable proxies. Here we document that iron oxide minerals, specifically the ratio of hematite to goethite (Hm/Gt), is a reasonable precipitation proxy. Using diffuse reflectance spectrophotometry, we measured samples from Ocean Drilling Program (ODP) 1143 drilling site (9°21.72'N, 113°17.11'E, 2777 m water depth) for hematite and goethite, whose formation processes are favored by opposing climate conditions. In order to determine the content of hematite and goethite we produced a set of calibration samples by removing the iron oxides to generate the natural matrix to which hematite and goethite in known percentages were added. From these calibration samples we developed a transfer function for determining hematite and goethite concentration from a sample's spectral reflectance. Applying this method to ODP 1143 sediments (top 34 m of a 510 m core with sampling interval of 10 cm) we were able to reconstruct a continuous precipitation history for SE Asia of the past 600 kyr using the Hm/Gt ratio as a proxy of the precipitation variability of Asian monsoon. The reliability of this Hm/Gt proxy is corroborated by its consistency with the stalagmite delta18O data from South China. Comparing long-term Hm/Gt records with the surface temperature gradient of equatorial Pacific Ocean, we found that monsoon precipitation and El Niño are correlated for the last 600 kyr. The development of El Niño-like conditions decreased SE Asia precipitation, whereas precipitation increases in response to La Niña intensification

Strontium isotope ratios of middle Eocene to Oligocene sediments from Maud Rise, Antarctica

A 87Sr/86Sr isotope curve of the middle Eocene to Oligocene was produced from analysis of foraminifera in Ocean Drilling Program Hole 689B, Maud Rise, near the coast of Antarctica. Sediments from the hole are well preserved with no evidence of diagenetic alteration. The sequence is nearly complete from 46.3 to 24.8 Ma, with an average sampling interval of 166 kyr. Excellent magnetostratigraphy in Hole 689B allows calibration to the geomagnetic polarity time scale of Cande and Kent (1992). Marine strontium isotopic ratios were nearly stable from 46.3 to 35.5 Ma, averaging near 0.70773, after which they began to increase. A slow increase began after 40.4 Ma, rising at a rate of only about 8*10**-6/m.y. from base values of 0.707707. From 35.5 Ma to 24.8 Ma the average slope increased to 40*10**-6/m.y. The slope remained constant at least until 24.8 Ma, when the record becomes discontinuous owing to unconformities. We evaluate several possible controls on the marine strontium isotope curve that could have led to the observed growth in 87Sr/86Sr ratios near the Eocene/Oligocene boundary. Three mechanisms are considered, including the onset of Antarctic glaciation, increased mountain building in the Himalayan-Tibetan region, and decreased hydrothermal activity. None of the mechanisms alone seems to adequately explain the increased 87Sr/86Sr ratios during the Oligocene. Glaciation as a weathering agent was too episodic and probably began too late to explain the upturn in marine 87Sr/86Sr ratios. There is evidence that uplift in the Himalayan-Tibetan region began in the Miocene, much too late to control Oligocene strontium isotope ratios. Lastly, hydrothermal flux changes since the Eocene were apparently not great enough alone to account for the rise in marine 87Sr/86Sr ratios. We suggest that a combination of causes, such as decreased hydrothermal activity perhaps followed by increased glaciation and mountain building, might best explain the growth of the marine 87Sr/86Sr curve during the Oligocene.

Criterios de calidad del servicio prestado en el ámbito de la línea de atraque de las terminales portuarias de contenedores

Esta Tesis Doctoral evalúa empíricamente la calidad del servicio en la línea de atraque de las terminales portuarias de contenedores. La metodología propuesta utiliza indicadores de calidad y se basa en el concepto de la segmentación de servicio. Para ello se desarrolla la teoría del Control Estadístico de Procesos (CEP) y se utilizan los gráficos de control para clasificar el servicio en las terminales de contenedores. El propósito de la Tesis es proporcionar una metodología basada en el Control Estadístico de Procesos (CEP) para evaluar la calidad del servicio y detectar las escalas de un servicio regular de línea que se encuentran fuera de control. Por tanto, la metodología se puede utilizar para detectar eventos que son indicativos de cambio real del proceso en la línea de atraque. Esta detección puede ser compleja pues las características de los procesos en terminales de contenedores son variables. La metodología proporciona mediante los gráficos de control criterios estadísticamente objetivos de cambio. Cuando el cambio es detectado y considerado bueno sus causas deben ser identificadas y posiblemente convertirse en la nueva forma de trabajar, cuando el cambio es negativo, entonces sus causas deberían ser identificadas y eliminadas. La Tesis Doctoral está organizado de la siguiente manera: La primera parte es la introducción, e incluye los capítulos 1 al 4, la segunda parte presenta el Estado del Arte (capítulo 5) y algunos de los estudios que han inspirado esta investigación, la tercera parte se centra en la metodología utilizada (capítulo 6) y su aplicación sobre un caso de estudio (capítulo 7). Finalmente, en la cuarta parte se presentan las conclusiones y se proponen algunas de las nuevas líneas de investigación que quedan abiertas (capítulo 8). This Thesis empirically evaluates the quality of service in the berthing face of container terminals. The methodology proposed is focused on quality of service indicators and is based on the concept of service segmentation. The Statistical Process Control (SPC) theory and the control charts are used to classify container terminal service. The aim of this Thesis is to provide a methodology based on Statistical Process Control that can evaluate the quality of service and also can detect scales of shipping liner service that are out of control. Therefore, the methodology can be used to detect events that are indicative of real change in the berthing process of container vessels. The methodology proposed allows simple detection of events that are indicative of actual process change in container terminals. This detection is complex because the characteristics of the processes are variable in the container terminals; the control chart provides statistically objective criteria of change. When change is detected and considered good its cause should be identified and possibly become the new way of working, where the change is bad then its cause should be identified and eliminated. This Thesis is organized as follows: The first part is the introduction (includes Chapters 1 to 4), the second part presents the State of the Art (Chapter 5) and some of the studies that have inspired this research. The third part focuses on the methodology used (Chapter 6) and its application to a case study (Chapter 7). Finally, Part 4 presents the conclusions and suggests future research (Chapter 8).

Gráfico de controle para monitoramento da razão da demanda e mão de obra em retaguarda de serviços no setor bancário.

O monitoramento da razão Z de duas variáveis através de gráfico de controle tem sido um tema recentemente explorado na literatura. Para analisar mais o assunto, o estudo avalia a eficiência e viabilidade de aplicação dessa ferramenta como suporte na tomada de decisão para gerenciamento de capacidade de mão de obra de retaguarda (doravante mencionado como Backoffice) de serviço de empresa do setor bancário. Tradicionalmente, gráficos de controle tem sido utilizados para monitorar o processo produtivo de manufaturas, mas recentemente tem sido adotado para monitoramento de alguns serviços. Apesar de ainda seguir muitos conceitos pioneiros na manufatura, a atividade do setor de serviços apresenta suas particularidades como, por exemplo, a impossibilidade de gerar estoque. Assim, a necessidade de adequar seus recursos à demanda torna-se essencial, sendo fundamental a gestão de controles e sua urgência para que possa reagir rapidamente em caso de variação de demanda e adequar sua capacidade. Em um cenário de restrição de recursos, planejar é crucial para evitar desperdícios e garantir eficiência. O objetivo deste estudo é apresentar o gráfico de controle como ferramenta para monitorar a razão de duas variáveis aleatórias: a demanda e a mão de obra em Backoffice de serviço em um banco. Nesse trabalho, gráfico de controle de Shewhart tradicional e gráfico de controle de Shewhart com regras suplementares são analisados e os resultados obtidos confirmam a possibilidade de utilização da ferramenta de gráficos de controle para o gerenciamento e adequação de mão de obra para atender a demanda. O monitoramento da razão (demanda/ mão de obra) ajudará o gestor a alocar adequadamente o time (mão de obra) de acordo com a demanda e a capacidade produtiva. Como contribuição, o estudo avalia o comportamento da razão Z = X/Y em situação de alta variabilidade da variável X e baixa variabilidade da variável Y .

Sinking rates of particles measured from deployments in the Atlantic Ocean based on seasonal data

The flux of materials to the deep sea is dominated by larger, organic-rich particles with sinking rates varying between a few meters and several hundred meters per day. Mineral ballast may regulate the transfer of organic matter and other components by determining the sinking rates, e.g. via particle density. We calculated particle sinking rates from mass flux patterns and alkenone measurements applying the results of sediment trap experiments from the Atlantic Ocean. We have indication for higher particle sinking rates in carbonate-dominated production systems when considering both regional and seasonal data. During a summer coccolithophorid bloom in the Cape Blanc coastal upwelling off Mauritania, particle sinking rates reached almost 570 m per day, most probably due the fast sedimentation of densely packed zooplankton fecal pellets, which transport high amounts of organic carbon associated with coccoliths to the deep ocean despite rather low production. During the recurring winter-spring blooms off NW Africa and in opal-rich production systems of the Southern Ocean, sinking rates of larger particles, most probably diatom aggregates, showed a tendency to lower values. However, there is no straightforward relationship between carbonate content and particle sinking rates. This could be due to the unknown composition of carbonate and/or the influence of particle size and shape on sinking rates. It also remains noticeable that the highest sinking rates occurred in dust-rich ocean regions off NW Africa, but this issue deserves further detailed field and laboratory investigations. We obtained increasing sinking rates with depth. By using a seven-compartment biogeochemical model, it was shown that the deep ocean organic carbon flux at a mesotrophic sediment trap site off Cape Blanc can be captured fairly well using seasonal variable particle sinking rates. Our model provides a total organic carbon flux of 0.29 Tg per year down to 3000 m off the NW African upwelling region between 5 and 35° N. Simple parameterisations of remineralisation and sinking rates in such models, however, limit their capability in reproducing the flux variation in the water column.