O objetivo principal deste trabalho é apresentar um modelo de análise probabilística do comportamento ao longo do tempo de estruturas de concreto. Para isso, é realizada a análise probabilística em conjunto com análise numérica. A análise numérica é realizada através de um programa computacional, baseado no método dos elementos finitos, que considera o comportamento não-linear e dependente do tempo dos materiais, assim como o processo evolutivo da construção. Para determinar o efeito das incertezas dos parâmetros é realizada uma análise probabilística, utilizando o método de amostragem por hipercubo latino. O modelo apresentado pode ser aplicado para a análise probabilística do comportamento ao longo do tempo das estruturas de concreto em geral. No entanto, foi aplicado na análise das flechas diferidas de lajes pré-moldadas formadas por vigotas com armação treliçada. Com esta análise, pôde-se propor um coeficiente multiplicador das flechas imediatas para a avaliação das flechas diferidas no tempo. O coeficiente multiplicador obtido para as lajes pré-moldadas formadas por vigotas com armação treliçada pode alcançar valores muito superiores ao fator 'alfa'f recomendado pela NBR 6118 (2003) para o caso de vigas de concreto armado. / The goal of this research is to present a probabilistic analysis model of the long-term behavior of concrete structures. For that, the probabilistic analysis is carried out together with numerical analysis. The numerical analysis is carried out using a software based on the finite element method that takes into account the nonlinear and time dependent behavior of the materials, as well as the evolutionary construction process. A probabilistic analysis is carried out in order to determine the effects of the uncertainties of the parameters, using latin hypercube sampling method. The presented model can be applied in the probabilistic analysis of the long-term behavior of concrete structures in general. However, it was applied in the analysis of the long-term deflections of precast slabs made by joist with lattice reinforcement. By this analysis, a multiplier coefficient of immediate deflections to evaluate long-term deflections could be proposed. The multiplier coefficient obtained for precast slabs made by joist with lattice reinforcement can reach values much higher than the factor 'alfa'f recommended by NBR 6118 (2003) for the case of reinforced concrete beams.

Dissertação(mestrado) - Universidade Federal do Rio Grande, Programa de Pós-Graduação em Engenharia Oceânica, Escola de Engenharia, 2009. / Submitted by Lilian M. Silva (lilianmadeirasilva@hotmail.com) on 2013-04-20T22:47:54Z No. of bitstreams: 1 Estudo probabilístico da resistência à compressão e da resistência à tração na flexão dos concretos utilizados na construção do dique seco do estaleiro Rio Grande, No Superporto, Em.pdf: 10848965 bytes, checksum: 809b5f8cbee32e8c634ff304349206bb (MD5) / Approved for entry into archive by Bruna Vieira(bruninha_vieira@ibest.com.br) on 2013-06-04T16:19:35Z (GMT) No. of bitstreams: 1 Estudo probabilístico da resistência à compressão e da resistência à tração na flexão dos concretos utilizados na construção do dique seco do estaleiro Rio Grande, No Superporto, Em.pdf: 10848965 bytes, checksum: 809b5f8cbee32e8c634ff304349206bb (MD5) / Made available in DSpace on 2013-06-04T16:19:35Z (GMT). No. of bitstreams: 1 Estudo probabilístico da resistência à compressão e da resistência à tração na flexão dos concretos utilizados na construção do dique seco do estaleiro Rio Grande, No Superporto, Em.pdf: 10848965 bytes, checksum: 809b5f8cbee32e8c634ff304349206bb (MD5) Previous issue date: 2009 / A variação presente nos ensaios de aceitação do concreto, sobretudo a resistência, torna fundamental a utilização de uma grande quantidade de dados amostrais para estabelecer parâmetros de avaliação e calibração das normas técnicas. Distintos controles tecnológicos, metodologias de dosagem e características dos materiais, são alguns dos fatores que fazem com que o concreto tenha peculiaridades relacionadas à região do planeta onde o mesmo é produzido.O presente trabalho aplicou diversos métodos de controle e aceitação de estruturas de concreto aos resultados práticos oriundos do concreto lançado na execução do dique seco do Estaleiro Rio Grande em construção na cidade de Rio Grande - RS. Esta obra é uma importante fonte de informações sobre a resistência e o comportamento do concreto visto que, na mesma, foi empregado desde o início um rigoroso controle de qualidade; gerando dados raramente disponíveis em obras portuárias brasileiras. Foram utilizados como base para este trabalho dois traços de concreto; um com adição de fibras e fck= 35 MPa e outro com adição de sílica ativa e fck= 40 MPa. Foram realizadas comparações entre as estimativas de resistência das normas brasileira, européia e norte-americana de concreto. Realizadas análises estatísticas de modelos teóricos de distribuição de probabilidade destas resistências. Além disso, foram estabelecidas correlações entre as resistências à tração e à compressão do concreto. O incremento de resistência do concreto ao longo do tempo também foi estudado, tanto para compressão como para a tração. As análises apresentadas permitem atestar o atendimento dos concretos utilizados na execução do dique seco quanto aos requisitos estabelecidos pelas normas brasileiras de concreto. / Due to the variability in the results of the concrete acceptance tests, especially in the resistance tests, it is fundamental to use a large number of sample data to establish the assessment parameters and to calibrate the standard codes. Different technological controls, mixing methodologies and material characteristics are some of the factors that cause the concrete having peculiarities proper of the region where it is produced. The present work has applied different methodsof control and acceptance of concrete structures to the test results of the concreteused in the construction of the Estaleiro Rio Grande dry-dock, in the city of Rio Grande – RS. This construction site is an important source of information about the concrete resistance and behavior, because it was adopted, since the beginning of the construction, a rigorous quality control. This quality control produced a number oftest results that is seldom available in the Brazilian harbors construction sites. In this work two different concrete mixes were studied: first a fiber reinforced concrete (FRC) with fck = 35 MPa, and a second one with silica fume addition with fck = 40 MPa. The resistance assessment formulations of the Brazilian, European and North American standard codes were compared. A statistical analysis of best the probability distribution models for the resistance test results was made. Besides, it was determined a correlation between the concrete tensile and compressive resistances. The increasing of the concreteresistance with time was also studied to compression as well as to tension. The analyses performed have showed that both concrete mixes used in the construction of this dry-dock have attained the quality standards required by the Brazilian standard codes for concrete.

Current complex service systems are usually comprised of many other components which are often external services performing particular tasks. The quality of service (QoS) attributes such as availability, cost, response time are essential to determine usability and eciency of such system. Obviously, the QoS of such compound system is dependent on the QoS of its components. However, the QoS of each component is naturally unstable and di erent each time it is called due to many factors like network bandwidth, workload, hardware resource, etc. This will consequently make the QoS of the whole system be unstable. This uncertainty can be described and represented with probability distributions. This thesis presents an approach to calculate the QoS of the system when the probability distributions of QoS of each component are provided by service provider or derived from historical data, along with the structure of their compositions. In addition, an analyzer tool is implemented in order to predict the QoS of the given compositions and probability distributions following the proposed approach. The output of the analyzer can be used to predict the behavior of the system to be implemented and to make decisions based on the expected performance. The experimental evaluation shows that the estimation is reliable with a minimal and acceptable error measurement.

Comúnmente los estudios geotécnicos de análisis de estabilidad de taludes se realizan mediante métodos determinísticos, en los cuales se obtiene como resultado un factor de seguridad (FS) de la estructura analizada. Sin embargo, estos métodos no cuantifican la incertidumbre en las variables de entrada (parámetros de resistencia del suelo), en el análisis y tampoco muestran los detalles de las variables más influyentes en la estabilidad del talud. Es por ello los métodos probabilísticos permiten superar estos problemas. Esta investigación tiene como objetivo principal realizar el análisis de estabilidad de taludes mediante el método probabilístico Primer Orden Segundo Momento (FOSM) dos recomendaciones de aplicabilidad, que ofrecen los autores Sandroni & Sayao (1992) y Mostyn y Li (1993). Se analizó un caso común y muy importantes porque fueron claves en la realización de métodos probabilísticos en la ingeniería geotécnica. El caso, es una de las carreteras más importantes de Brasil, el cual sufrió deslizamiento 2 años después de su construcción. Se realizó el análisis probabilístico dando como resultado que los parámetros de confiabilidad de la estructura eran muy bajos y la probabilidad de rotura muy alta. Se plantea la propuesta de solución de estabilidad con una probabilidad de rotura mínima. La investigación se realizó con datos realizados en Brasil, por la cantidad de datos que requieren los estudios probabilísticos. Los tipos de suelos que se estudiaron fueron cohesivos, los cuales se pueden encontrar también en la selva peruana. Sin embargo, no se está tomando en cuenta proyectos nacionales por lo que no cuentan con la información necesaria para la aplicación de esta metodología. / Geotechnical studies on slope stability analyzes are performed using deterministic methods, from which are obtained as a result of a safety factor (FS) of the structure analyzed. However, these methods do not quantify the uncertainty in the input variables (parameters of soil resistance), analysis and do not show the details of the most influential variables in the stability of the slope. Therefore, probabilistic methods can overcome these problems. This research has as main objective the analysis of slope stability by probabilistic first order second moment method (FOSM) by two applicability recommendation that we provide the authors Sandroni & Sayao (1992) and Mostyn and Li (1993); and a comparison with the results obtained. Resulting in the second method is more accurate by being number of analysis performed. The case is one of the most important roads in Brazil which suffered a landslide two years after its construction. probabilistic analysis result that reliability parameters of the structure were very low and very high probability of rupture was performed. It was decided to make the solution stability with a minimum breaking probability. The research was carried out with studies of Brazil, for the amount of data that is required when probabilistic studies are conducted. Soil types found were generally cohesive, which can be found in the Peruvian jungle. However, there is no necessary data projects with this amount of data is required. / Tesis

No description available.

Sublevel caving operations at great depths are subjected both to large stress concentrations that are redistributed as the mining front progresses and to mining-induced seismicity. This is the case for Kiirunavaara mine, Sweden’s largest underground mine. Since the mine was declared seismically active in 2007 / 2008, large rockfalls controlled by structures have happened in many parts of the mine, despite the use of rock support systems designed for bearing dynamic loads. A novel layout for sublevel caving operations, internally named “fork layout” is being tested at a satellite mine. This layout was conceived to place the ore-parallel longitudinal footwall drifts further away from the contact between the orebody and footwall drifts. That way, the differential stresses that generate stress-related damages are expected to be reduced. However, the effect of implementing the fork layout on the hazard potential for structurally controlled rockfalls has not been studied in detail yet. Large rockfalls that occurred in different parts of the mine were analysed with respect to their structures, location of the damage event and type of excavation. The majority of these occurred at footwall drift intersections. Information from damage mapping and seismic events that triggered these rockfalls was used to generate a conceptual model that illustrates the relative spatial relation between the seismic source and damage location. In addition, the seismic source parameters of the events that triggered these rockfalls were processed using scaling laws to obtain ground motion parameters such as peak particle velocity and acceleration at the damage site. The effect of implementing the fork layout on rockfall hazard was tested in the intersections between footwall drifts and crosscuts (FD-CC), and intersections between access and footwall drifts (AD-FD) in two production blocks, using the traditional layout for sublevel caving mining as a point of comparison. Two different fork layouts were tested, FD-CC at 80° (or AD-FD at 100°) and FD-CC at 70° (or AD-FD at 110°). Structural data available from face mapping and oriented core logging was used to define predominant joint sets at the investigated blocks. Using the structural input, wedge volumes at the intersections were modelled deterministically and probabilistically in Unwedge. The variations in wedge volumes formed at the intersections between layouts were used as a proxy for rockfall potential, meaning that if a layout reduced the wedge size, the smaller the rockfall hazard if triggered by a seismic event, and vice versa. It was concluded that most rockfalls at the FD-CC intersections are controlled by structures from three major joint sets. It was observed that rockfalls at FD-CC intersections occurred more often at certain footwall drift orientations. Many seismic events that triggered these rockfalls are located close to the ore passes and generated ground accelerations between 0.5 to 10 times the gravity acceleration. Implementing fork layouts with FD-CC at 80° intersection angle generates larger wedges than the traditional layout and thus, scenarios with a higher rockfall hazard. On the other hand, using fork layouts with FD-CC at 70° intersection angle reduces wedge size at the southern FD-CC intersections; hence, the rockfall hazard is reduced in these intersections. In the northern FD-CC intersections, the wedge volumes are increased and thus, a higher rockfall potential is generated in these intersections. AD-FD at 110° intersection angle generates also a smaller rockfall hazard than the traditional layout in both production blocks.

Automobile système embarqué est une architecture distribuée de l'ordinateur des applications basées sur. La prolifération des systèmes embarqués dans une automobile a apporté de nombreux avantages,tels que le remplacement du système mécanique ancienne avec capteur électronique en réseau et desactionneurs, par exemple, dans des applications telles suspensions adaptatives. Le remplacement des systèmes mécaniques avec ceux électroniques et l'intégration de nouvelles fonctionnalités dans l'électronique soulève une grave préoccupation, c'est de fournir des garanties que ces systèmes embarqués seront en mesure d'effectuer, même dans des environnements difficiles, en particulier dans un système critique pour la sécurité comme un automobile. De plus, ceux-ci l'actualité informatique applications à la demande, imposée par un processus physique.Par exemple, pour éviter un événement catastrophique comme un accident de la demande de freinage doit répondre aux contraintes de minutage. Ce qui implique que la durée de temps entre l'instance de l'application du frein (à la pédale de frein) et l'instance de l'actionnement au niveau des roues d'un véhicule automobile doit être inférieure à la limite. En outre, l'application de freinage est généralement répartie sur le nombre de nœuds, qui sont embarqués communicants les uns avec les autres en utilisant une ressource de communication partagée. Par conséquent, il est important que nous fournissons des garanties que la demande, individuellement et collectivement, est atteinte de ses contrainte temporelle; qui est dans la composition de plusieurs nœuds embarqués. En outre, la prolifération des applications informatiques est également livré avec une hétérogénéité croissante et la complexité de l'architecture intégrée, ce qui conduira à l'augmentation de la complexité de l'analyse pour les systèmes automobiles.Par conséquent, il ya un besoin croissant d'assurer que ces systèmes automobiles embarqués répondre à des contraintes temporelles et de fournir des garanties de sécurité au cours de leur fonctionnement normal ou lors de situations critiques. Cette thèse vise à développer les analyses d'ordonnançabilité pour systèmes automobiles et les réseaux intégrés, avec le but de faciliter,d'une manière rentable et fiable, la conception et l'analyse des systèmes embarqués automobiles. Les analyses sont élaborées et appliquées dans le contexte de l'automobile; de ​​façon à réduire le risque d'échec en raison de délai: les limites du matériel; frais généraux de mise en œuvre, et les interférences dues à la circulation probaliste / Automotive embedded system is a distributed architecture of computer-based applications. The proliferation of embedded systems in an automobile has brought numerous benefits; such as replacement of old mechanical system with networked electronic sensor and actuators, for example, in applications like adaptive suspensions. The replacement of mechanical systems with electronic onesand the integration of new functionality in electronics raises a serious concern; that is to provide guarantees that these embedded systems will be able to perform, even in harsh environments, particularly in a safety-critical system like an automobile.Moreover, these computer-based applications demand timeliness, imposed by a physical process. For example, to avoid a catastrophic event like a crash the braking application has to meet thetiming-constraints. This implies that the time duration between the instance of application of the brake (at brake pedal) and the instance of actuation at the wheels of an automobile should be less than the deadline. Moreover, the braking application is usually spread over number of embedded nodes, which are communicating with each other using a shared communication resource. Therefore, it is important that we provide some guarantees that an application, individually and collectively, is meeting its timing constraint; that is in the composition of multiple embedded nodes. Moreover, theproliferation of computer-based applications also comes with an increasing heterogeneity and complexity of the embedded architecture; which lead to the increase in the complexity of the analysis for the automotive systems Therefore, there is an increasing need to ensure that these automotive embedded systems meet temporal constraints and provide safety guarantees during their normal operation or during critical situations. This thesis aims at developing the schedulability analyses for automotive systems and embedded networks; with the aim to facilitate, in a cost-effective and reliable manner, the design and analysis of automotive embedded systems. The analyses are developed and applied in the automotive context; so as to reduce the risk of deadline failure due to: hardware limitations ; implementation overheads; and nterference due to probabilistic traffic

A Engenharia de Ventos Baseada em Desempenho (Performance-based Wind Engineering - PBWE) é uma filosofia de projeto que preconiza identificar e quantificar as incertezas envolvidas no projeto estrutural a fim de assegurar níveis previsíveis de desempenho às edificações, não mais gerenciando o risco através da clássica abordagem determinística. Contudo, devido à recente proposição da metodologia, ainda há poucos estudos relacionados à PBWE, cada qual apresentando diferentes limitações. Assim, o presente trabalho propõe uma adaptação da metodologia da Engenharia de Ventos Baseada em Desempenho à análise probabilística do comportamento de torres metálicas, avaliando diferentes modelos de cálculo para estimativa das forças do vento neste tipo de estrutura. Para tanto, investigou-se as incertezas envolvidas na caracterização do campo de ventos e da resistência estrutural e foram analisados quatro métodos distintos para a estimativa das forças de vento em torres metálicas: dois procedimentos de cálculo correspondentes à norma brasileira de ventos ABNT NBR 6123:1988 (ABNT, 1988), a metodologia de Davenport (1993) e a de Holmes (1994). Um estudo de caso envolvendo a estimativa da confiabilidade de uma torre de telecomunicação também foi conduzido. Constatou-se que ambos os procedimentos de cálculo admitidos conduzem a níveis de segurança de mesma ordem de grandeza e que a elaboração de projetos de torres considerando a direção de incidência do vento como sendo a mais desfavorável à estrutura é demasiadamente conservadora. Como contribuição, verifica-se que o projeto ótimo de torres pode ser alcançado com base no nível de segurança desejado para diferentes velocidades máxima de vento associadas a intervalos de recorrência específicos. / Performance-based Wind Engineering (PBWE) is a design philosophy that aims to identify and quantify the uncertainties involved in the structural design in order to ensure predictable performance levels to buildings, no longer managing risk through the classical deterministic approach. However, due to the recent proposal of the methodology, there are few studies related to PBWE, each presenting different limitations. Thus, this paper proposes an adaptation of the Performance-based Wind Engineering methodology to the probabilistic analysis of the behavior of steel towers, evaluating different calculation models for estimating wind forces on this type of structure. To this end, uncertainties involved in the characterization of the wind field and structural strength were investigated and four different methods for the estimation of wind forces on steel towers were analyzed: two procedures relative to the Brazilian winds standard ABNT NBR 6123:1988 (ABNT, 1988), and the methodologies of Davenport (1993) and Holmes (1994). A case study concerning the reliability estimation of a telecommunication tower was also conducted. It was found that both assumed calculation procedures lead to security levels of the same order of magnitude and that the design of towers considering that the wind always blows from the worst direction is too conservative. As a contribution, it is found that the optimum design of towers can be achieved based on the desired security level for different maximum wind speeds associated to specific recurrence intervals.

The NP-complete k-SAT problem - decide wether a given formula is satisfiable - is of fundamental importance in theoretical computer science. In this dissertation we study random 4-SAT formulas with > 116 n^2 clauses. These formulas are almost surly unsatisfiable. Here we show the existence of a polynomial time algorithm that certifies the unsatisfiability. Therefore we study the discrepancy of hypergraphs and multigraphs. We also combine spectral techniques with approximation algorithms to achieve the new result. Our new algorithm is adaptable for Not-All-Equal-4-SAT and the 2-colouring of 4-uniform hypergraphs. We also extends the Hajos construction of non k-colourable graphs to non k-colourable uniform hypergraphs. / Das NP-vollständige Problem k-SAT ist von zentraler Bedeutung in der theoretischen Informatik. In der Dissertation werden zufällige 4-SAT-Formeln mit > n^2 vielen Klauseln studiert. Diese Formeln sind mit hoher Wahrscheinlichkeit unerfüllbar. Hier wird erstmalig die Existenz eines Algorithmus gezeigt, der diese Unerfüllbarkeit effizient verifiziert. Hierfür wird die geringe Diskrepanz von Hypergrpahen und Multigraphen betrachtet. Der Schlüssel zu diesem Algorithmus liegt in der Kombination von spektralen Techniken mit Approximationsalgorithmen der klassischen kombinatorischen Optimierung. Der vorgestellte Algorithmus kann auf den effizienten Nachweis der Unerfüllbarkeit von Not-All-Equal-4-SAT-Formeln und die Nicht-2-Färbbarkeit von 4-uniformen Hypergraphen erweitert werden. Es wird ebenfalls eine Erweiterung der Hajos-Konstruktion nicht k-färbbarer Graphen auf nicht k-färbbare uniforme Hypergraphen angegeben.

A Engenharia de Ventos Baseada em Desempenho (Performance-based Wind Engineering - PBWE) é uma filosofia de projeto que preconiza identificar e quantificar as incertezas envolvidas no projeto estrutural a fim de assegurar níveis previsíveis de desempenho às edificações, não mais gerenciando o risco através da clássica abordagem determinística. Contudo, devido à recente proposição da metodologia, ainda há poucos estudos relacionados à PBWE, cada qual apresentando diferentes limitações. Assim, o presente trabalho propõe uma adaptação da metodologia da Engenharia de Ventos Baseada em Desempenho à análise probabilística do comportamento de torres metálicas, avaliando diferentes modelos de cálculo para estimativa das forças do vento neste tipo de estrutura. Para tanto, investigou-se as incertezas envolvidas na caracterização do campo de ventos e da resistência estrutural e foram analisados quatro métodos distintos para a estimativa das forças de vento em torres metálicas: dois procedimentos de cálculo correspondentes à norma brasileira de ventos ABNT NBR 6123:1988 (ABNT, 1988), a metodologia de Davenport (1993) e a de Holmes (1994). Um estudo de caso envolvendo a estimativa da confiabilidade de uma torre de telecomunicação também foi conduzido. Constatou-se que ambos os procedimentos de cálculo admitidos conduzem a níveis de segurança de mesma ordem de grandeza e que a elaboração de projetos de torres considerando a direção de incidência do vento como sendo a mais desfavorável à estrutura é demasiadamente conservadora. Como contribuição, verifica-se que o projeto ótimo de torres pode ser alcançado com base no nível de segurança desejado para diferentes velocidades máxima de vento associadas a intervalos de recorrência específicos. / Performance-based Wind Engineering (PBWE) is a design philosophy that aims to identify and quantify the uncertainties involved in the structural design in order to ensure predictable performance levels to buildings, no longer managing risk through the classical deterministic approach. However, due to the recent proposal of the methodology, there are few studies related to PBWE, each presenting different limitations. Thus, this paper proposes an adaptation of the Performance-based Wind Engineering methodology to the probabilistic analysis of the behavior of steel towers, evaluating different calculation models for estimating wind forces on this type of structure. To this end, uncertainties involved in the characterization of the wind field and structural strength were investigated and four different methods for the estimation of wind forces on steel towers were analyzed: two procedures relative to the Brazilian winds standard ABNT NBR 6123:1988 (ABNT, 1988), and the methodologies of Davenport (1993) and Holmes (1994). A case study concerning the reliability estimation of a telecommunication tower was also conducted. It was found that both assumed calculation procedures lead to security levels of the same order of magnitude and that the design of towers considering that the wind always blows from the worst direction is too conservative. As a contribution, it is found that the optimum design of towers can be achieved based on the desired security level for different maximum wind speeds associated to specific recurrence intervals.