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Multiobjective Robust Design of the Double Wishbone Suspension System Based on Particle Swarm Optimization

Cheng, Xianfu; Lin, Yuqun
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
Publicado em 11/02/2014 Português
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The performance of the suspension system is one of the most important factors in the vehicle design. For the double wishbone suspension system, the conventional deterministic optimization does not consider any deviations of design parameters, so design sensitivity analysis and robust optimization design are proposed. In this study, the design parameters of the robust optimization are the positions of the key points, and the random factors are the uncertainties in manufacturing. A simplified model of the double wishbone suspension is established by software ADAMS. The sensitivity analysis is utilized to determine main design variables. Then, the simulation experiment is arranged and the Latin hypercube design is adopted to find the initial points. The Kriging model is employed for fitting the mean and variance of the quality characteristics according to the simulation results. Further, a particle swarm optimization method based on simple PSO is applied and the tradeoff between the mean and deviation of performance is made to solve the robust optimization problem of the double wishbone suspension system.

The Spatial Resolution of Epidemic Peaks

Mills, Harriet L.; Riley, Steven
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 10/04/2014 Português
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The emergence of novel respiratory pathogens can challenge the capacity of key health care resources, such as intensive care units, that are constrained to serve only specific geographical populations. An ability to predict the magnitude and timing of peak incidence at the scale of a single large population would help to accurately assess the value of interventions designed to reduce that peak. However, current disease-dynamic theory does not provide a clear understanding of the relationship between: epidemic trajectories at the scale of interest (e.g. city); population mobility; and higher resolution spatial effects (e.g. transmission within small neighbourhoods). Here, we used a spatially-explicit stochastic meta-population model of arbitrary spatial resolution to determine the effect of resolution on model-derived epidemic trajectories. We simulated an influenza-like pathogen spreading across theoretical and actual population densities and varied our assumptions about mobility using Latin-Hypercube sampling. Even though, by design, cumulative attack rates were the same for all resolutions and mobilities, peak incidences were different. Clear thresholds existed for all tested populations, such that models with resolutions lower than the threshold substantially overestimated population-wide peak incidence. The effect of resolution was most important in populations which were of lower density and lower mobility. With the expectation of accurate spatial incidence datasets in the near future...

Performance Improvement of a Return Channel in a Multistage Centrifugal Compressor Using Multiobjective Optimization

Nishida, Yoshifumi; Kobayashi, Hiromi; Nishida, Hideo; Sugimura, Kazuyuki
Fonte: American Society of Mechanical Engineers Publicador: American Society of Mechanical Engineers
Tipo: Artigo de Revista Científica
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The effect of the design parameters of a return channel on the performance of a multistage centrifugal compressor was numerically investigated, and the shape of the return channel was optimized using a multiobjective optimization method based on a genetic algorithm to improve the performance of the centrifugal compressor. The results of sensitivity analysis using Latin hypercube sampling suggested that the inlet-to-outlet area ratio of the return vane affected the total pressure loss in the return channel, and that the inlet-to-outlet radius ratio of the return vane affected the outlet flow angle from the return vane. Moreover, this analysis suggested that the number of return vanes affected both the loss and the flow angle at the outlet. As a result of optimization, the number of return vane was increased from 14 to 22 and the area ratio was decreased from 0.71 to 0.66. The radius ratio was also decreased from 2.1 to 2.0. Performance tests on a centrifugal compressor with two return channels (the original design and optimized design) were carried out using two-stage test apparatus. The measured flow distribution exhibited a swirl flow in the center region and a reversed swirl flow near the hub and shroud sides. The exit flow of the optimized design was more uniform than that of the original design. For the optimized design...

Cystic Echinococcosis in the Province of Álava, North Spain: The Monetary Burden of a Disease No Longer under Surveillance

Carabin, Hélène; Balsera-Rodríguez, Francisco J.; Rebollar-Sáenz, José; Benner, Christine T.; Benito, Aitziber; Fernández-Crespo, Juan C.; Carmena, David
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 07/08/2014 Português
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Cystic echinococcosis (CE) is endemic in Spain but has been considered non-endemic in the province of Álava, Northern Spain, since 1997. However, Álava is surrounded by autonomous regions with some of the highest CE prevalence proportions in the nation, casting doubts about the current classification. The purpose of this study is to estimate the frequency of CE in humans and animals and to use this data to determine the societal cost incurred due to CE in the Álava population in 2005. We have identified epidemiological and clinical data from surveillance and hospital records, prevalence data in intermediate (sheep and cattle) host species from abattoir records, and economical data from national and regional official institutions. Direct costs (diagnosis, treatment, medical care in humans and condemnation of offal in livestock species) and indirect costs (productivity losses in humans and reduction in growth, fecundity and milk production in livestock) were modelled using the Latin hypercube method under five different scenarios reflecting different assumptions regarding the prevalence of asymptomatic cases and associated productivity losses in humans. A total of 13 human CE cases were reported in 2005. The median total cost (95% credible interval) of CE in humans and animals in Álava in 2005 was estimated to range between €61...

Constructing Rigorous and Broad Biosurveillance Networks for Detecting Emerging Zoonotic Outbreaks

Brown, Mac; Moore, Leslie; McMahon, Benjamin; Powell, Dennis; LaBute, Montiago; Hyman, James M.; Rivas, Ariel; Jankowski, Mark; Berendzen, Joel; Loeppky, Jason; Manore, Carrie; Fair, Jeanne
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 06/05/2015 Português
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Determining optimal surveillance networks for an emerging pathogen is difficult since it is not known beforehand what the characteristics of a pathogen will be or where it will emerge. The resources for surveillance of infectious diseases in animals and wildlife are often limited and mathematical modeling can play a supporting role in examining a wide range of scenarios of pathogen spread. We demonstrate how a hierarchy of mathematical and statistical tools can be used in surveillance planning help guide successful surveillance and mitigation policies for a wide range of zoonotic pathogens. The model forecasts can help clarify the complexities of potential scenarios, and optimize biosurveillance programs for rapidly detecting infectious diseases. Using the highly pathogenic zoonotic H5N1 avian influenza 2006-2007 epidemic in Nigeria as an example, we determined the risk for infection for localized areas in an outbreak and designed biosurveillance stations that are effective for different pathogen strains and a range of possible outbreak locations. We created a general multi-scale, multi-host stochastic SEIR epidemiological network model, with both short and long-range movement, to simulate the spread of an infectious disease through Nigerian human...

Estimated Under-Five Deaths Associated with Poor-Quality Antimalarials in Sub-Saharan Africa

Renschler, John P.; Walters, Kelsey M.; Newton, Paul N.; Laxminarayan, Ramanan
Fonte: The American Society of Tropical Medicine and Hygiene Publicador: The American Society of Tropical Medicine and Hygiene
Tipo: Artigo de Revista Científica
Publicado em 03/06/2015 Português
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Many antimalarials sold in sub-Saharan Africa are poor-quality (falsified, substandard, or degraded), and the burden of disease caused by this problem is inadequately quantified. In this article, we estimate the number of under-five deaths caused by ineffective treatment of malaria associated with consumption of poor-quality antimalarials in 39 sub-Saharan countries. Using Latin hypercube sampling our estimates were calculated as the product of the number of private sector antimalarials consumed by malaria-positive children in 2013; the proportion of private sector antimalarials consumed that were of poor-quality; and the case fatality rate (CFR) of under-five malaria-positive children who did not receive appropriate treatment. An estimated 122,350 (interquartile range [IQR]: 91,577–154,736) under-five malaria deaths were associated with consumption of poor-quality antimalarials, representing 3.75% (IQR: 2.81–4.75%) of all under-five deaths in our sample of 39 countries. There is considerable uncertainty surrounding our results because of gaps in data on case fatality rates and prevalence of poor-quality antimalarials. Our analysis highlights the need for further investigation into the distribution of poor-quality antimalarials and the need for stronger surveillance and regulatory efforts to prevent the sale of poor-quality antimalarials.

Surrogate Model Application to the Identification of Optimal Groundwater Exploitation Scheme Based on Regression Kriging Method—A Case Study of Western Jilin Province

An, Yongkai; Lu, Wenxi; Cheng, Weiguo
Fonte: MDPI Publicador: MDPI
Tipo: Artigo de Revista Científica
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This paper introduces a surrogate model to identify an optimal exploitation scheme, while the western Jilin province was selected as the study area. A numerical simulation model of groundwater flow was established first, and four exploitation wells were set in the Tongyu county and Qian Gorlos county respectively so as to supply water to Daan county. Second, the Latin Hypercube Sampling (LHS) method was used to collect data in the feasible region for input variables. A surrogate model of the numerical simulation model of groundwater flow was developed using the regression kriging method. An optimization model was established to search an optimal groundwater exploitation scheme using the minimum average drawdown of groundwater table and the minimum cost of groundwater exploitation as multi-objective functions. Finally, the surrogate model was invoked by the optimization model in the process of solving the optimization problem. Results show that the relative error and root mean square error of the groundwater table drawdown between the simulation model and the surrogate model for 10 validation samples are both lower than 5%, which is a high approximation accuracy. The contrast between the surrogate-based simulation optimization model and the conventional simulation optimization model for solving the same optimization problem...

The Spread of Fecally Transmitted Parasites in Socially Structured Populations

Nunn, Charles Lindsay; Thrall, Peter H.; Leendertz, Fabian H.; Boesch, Christophe
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
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Mammals are infected by a wide array of gastrointestinal parasites, including parasites that also infect humans and domesticated animals. Many of these parasites are acquired through contact with infectious stages present in soil, feces or vegetation, suggesting that ranging behavior will have a major impact on their spread. We developed an individual-based spatial simulation model to investigate how range use intensity, home range overlap, and defecation rate impact the spread of fecally transmitted parasites in a population composed of social groups (i.e., a socially structured population). We also investigated the effects of epidemiological parameters involving host and parasite mortality rates, transmissibility, disease–related mortality, and group size. The model was spatially explicit and involved the spillover of a gastrointestinal parasite from a reservoir population along the edge of a simulated reserve, which was designed to mimic the introduction pathogens into protected areas. Animals ranged randomly within a “core” area, with biased movement toward the range center when outside the core. We systematically varied model parameters using a Latin hypercube sampling design. Analyses of simulation output revealed a strong positive association between range use intensity and the prevalence of infection. Moreover...

Calculating failure probabilities of passive systems during transients

Mackay, Francisco J
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 171 p.
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A time-dependent reliability evaluation of a two-loop passive Decay Heat Removal (DHR) system was performed as part of the iterative design process for a helium-cooled fast reactor. The system was modeled using RELAP5-3D. The uncertainties in input parameters were assessed and were propagated through the model using Latin Hypercube Sampling. An important finding was the discovery that the smaller pressure loss through the DHR heat exchanger than through the core would make the flow to bypass the core through one DHR loop, if two loops operated in parallel. This finding is a warning against modeling only one lumped DHR loop and assuming that n of them will remove n times the decay power. Sensitivity analyses revealed that there are values of some input parameters for which failures are very unlikely. The calculated conditional (i.e., given the LOCA) failure probability was deemed to be too high leading to the identification of several design changes to improve system reliability. This study is an example of the kinds of insights that can be obtained by including a reliability assessment in the design process. It is different from the usual use of PSA in design, which compares different system configurations, because it focuses on the thermal-hydraulic performance of a safety function.; by Francisco J. Mackay.; Thesis (S.M.)--Massachusetts Institute of Technology...

A quadrature-based technique for robust design with computer simulations

Lin, Yiben
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 90 p.
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This thesis presents a method for estimating transmitted variance to enable robust parameter design in computer simulations. This method is based on the Hermite-Gaussian quadrature for a single input. It is extended to multiple variables, in which case, for simulations with n randomly varying inputs, the method requires 4n + 1 samples. For situations in which the polynomial response is separable, it is proven that 1) the method gives exact transmitted variance if the response is up to a fourth-order separable polynomial response and 2) the error of the transmitted variance estimated by the method is smaller than zero if the response is a fifth-order separable polynomial response. For situations in which the polynomial response is not separable, two probability models based on the effect hierarchy principle are used to generate a large number of polynomial response functions. The proposed method and alternative methods are applied to these polynomial response functions to investigate accuracy. For typical populations of problems, it is shown that the method has good accuracy, providing less than 5% error in 90% of cases.; (cont.) The proposed method provides much better accuracy than Latin Hypercube Sampling or Hammersley Sequence Sampling assuming these techniques are also restricted to using 4n + 1 samples. Hammersley Sequence Sampling requires at least ten times the number of samples to provide approximately the same degree of accuracy as the quadrature technique. A cubature method provides slightly better accuracy than the proposed method...

Uncertainty in Greenhouse Emissions and Costs of Atmospheric Stabilization

Webster, Mort D.; Paltsev, Sergey; Parsons, John E.; Reilly, John M.; Jacoby, Henry D.
Fonte: MIT Joint Program on the Science and Policy of Global Change Publicador: MIT Joint Program on the Science and Policy of Global Change
Tipo: Relatório
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We explore the uncertainty in projections of emissions, and costs of atmospheric stabilization applying the MIT Emissions Prediction and Policy Analysis model, a computable general equilibrium model of the global economy. Monte Carlo simulation with Latin Hypercube Sampling is applied to draw 400 samples from probability distributions for 100 parameters in the EPPA model, including labor productivity growth rates, energy efficiency trends, elasticities of substitution, costs of advanced technologies, fossil fuel resource availability, and trends in emissions factors for urban pollutants. The resulting uncertainty in emissions and global costs is explored under a scenario assuming no climate policy and four different targets for stabilization of atmospheric greenhouse gas concentrations. We find that most of the IPCC emissions scenarios are outside the 90% probability range of emissions in the absence of climate policy, and are consistent with atmospheric stabilization scenarios. We find considerable uncertainty in the emissions prices under stabilization. For example, the CO2 price in 2060 under an emissions constraint targeted to achieve stabilization at 650 ppm has a 90% range of $14 to $88 per ton CO2, and a 450 ppm target in 2060 has a range of $241 to $758. We also explore the relative contribution of uncertainty in different parameters to the resulting uncertainty in emissions and costs and find that...

Risk-informed design changes for a passive cooling system

Patalano, Giovanbattista
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 121 p.
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The failure probability of a passive decay heat removal system after a LOCA is evaluated as part of a risk-informed design process for a helium-cooled fast reactor. The system was modeled using RELAP5-3D. The epistemic uncertainties in input parameters as well as the epistemic model uncertainties in the code were assessed and propagated through the model using Latin hypercube sampling. The changes in the design that we investigated reduced the overall failure probability of the system by reducing the impact of the major contributor to the failure probability. Sensitivity analyses led to two unexpected results. First, the key factors affecting the system failure probability are the location of the thermal insulation (inside or outside the hot leg) and the uncertainty in the insulation thermal conductivity. Second, the heat transfer coefficient in the core is not as important as one might expect. Our results show that the heat transfer coefficient in the containment structures is more important. Different methods for sensitivity analysis were applied and gave consistent results.; Giovanbattista Patalano.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2007.; Includes bibliographical references (p. 47-49).

Assessing methods for predicting retrofit energy savings in buildings : case study of a Norwegian school

Ricker, Elizabeth, S.M. (Elizabeth Ann). Massachusetts Institute of Technology
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 338 p.
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This work investigates methods for predicting retrofit energy savings in existing Norwegian buildings. A case study is performed on a 30 year old primary school in Trondheim, Norway. The energy consumption in the school is simulated with the EnergyPlus computer software and calibrated against measured utility data. Two simulation calibration techniques are investigated: manual calibration and Latin Hypercube Monte Carlo (LHMC) analysis. LHMC is a statistical technique for calibrating building energy simulations, whereas manual calibrations are tuned by the modeler. Calibrated simulations are then used to predict the potential for energy savings under a number of retrofit conditions. Methods of quantifying the uncertainty in energy savings predictions are also investigated. The LHMC is shown to be most appropriate for models with a high number of uncertain building simulation inputs and when monthly utility data is available. However, manual calibration is found to be more suitable for simulations with fewer uncertain inputs and when hourly utility data is available. The retrofit analysis with the manually calibrated model predicted savings of up to 55% of the 173 kWh/m² base-year energy consumption in the case study building.; by Elizabeth Ricker.; Thesis (S.M.)--Massachusetts Institute of Technology...

Mapeamento pedológico digital da folha Botucatu (SF-22-Z-B-VI-3): treinamento de dados em mapa tradicional e validação de campo.

SILVA, C. C. da; COELHO, R. M.; OLIVEIRA, S. R. de M.; ADAMI, S. F.
Fonte: Revista Brasileira de Ciência do Solo, Campinas, v. 37, n. 4., p. 846-857, 2013. Publicador: Revista Brasileira de Ciência do Solo, Campinas, v. 37, n. 4., p. 846-857, 2013.
Tipo: Artigo em periódico indexado (ALICE)
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O mapeamento digital de solos permite prever padrões de ocorrência de solos com base em áreas de referência e no uso de técnicas de mineração de dados para modelar associações solo-paisagem. Os objetivos deste trabalho foram produzir um mapa pedológico digital por meio de técnicas de mineração de dados aplicadas a variáveis geomorfométricas e de geologia, com base em áreas de referência; e testar a confiabilidade desse mapa por meio de validação em campo com diferentes sistemas de amostragem. O mapeamento foi realizado na folha Botucatu (SF-22-Z-B-VI-3), utilizando-se as folhas 1:50.000, Dois Córregos e São Pedro, como áreas de referência. Variáveis descritoras do relevo e de geologia associadas às unidades de mapeamento pedológico das áreas de referência compuseram a matriz de dados de treinamento. A matriz foi analisada pelo algoritmo PART de árvore de decisão, do aplicativo Weka (Waikato Environment for Knowledge Analysis), que cria regras de classificação. Essas regras foram aplicadas aos dados geomorfométricos e geológicos da folha Botucatu, para predição de unidades de mapeamento pedológico. A validação de campo dos mapas digitais deu-se por meio de amostragem por transectos em uma unidade de mapeamento da folha São Pedro e de forma aleatório-estratificada na folha Botucatu. A avaliação da unidade de mapeamento na folha São Pedro verificou confiabilidade...

Uso da otimização sequencial aproximada a problemas Uni e multiobjetivos de gerenciamento de reservatórios

Pinto, Jefferson Wellano Oliveira
Fonte: Universidade Federal de Pernambuco Publicador: Universidade Federal de Pernambuco
Tipo: Dissertação
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Na área da engenharia de reservatórios de petróleo, um dos grandes desafios enfrentados é a busca da melhor solução para a produção de óleo. Uma ferramenta disponível para previsão da produção e que fornece informações para o controle da mesma é a simulação computacional de reservatórios. Com base nessa ferramenta, a simulação do campo pode ser conduzido de forma automática através de procedimentos de otimização. Neste trabalho será abordada a otimização do gerenciamento da injeção de água, tendo como variáveis as vazões atribuídas a cada poço produtor e injetor sob diferentes condições operacionais. O valor presente líquido (VPL), a produção acumulada de óleo e a injeção acumulada de água são as funções objetivo utilizadas. Tais problemas, por envolverem repetidas simulações numéricas, na maioria das vezes são computacionalmente onerosos. Visando contornar este custo, modelos substitutos podem ser utilizados. O presente trabalho propõe apresentar uma ferramenta para a otimização de problemas de gerenciamento de reservatório uni e multiobjetivos utilizando um acoplamento das técnicas Soma Ponderada (Weighted Sum (WS)) e Intersecção Contorno-Normal (Normal Boundary Intersection (NBI)) à estratégia de otimização sequencial aproximada (Sequential Aproximation Optimization (SAO))...

Surrogate modeling techniques and heuristic optimization methods applied to design and identification problems

Viana, Felipe Antonio Chegury
Fonte: Universidade Federal de Uberlândia Publicador: Universidade Federal de Uberlândia
Tipo: Tese de Doutorado
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Avanços na capacidade de processamento computacional popularizaram a otimização numérica como uma ferramenta de engenharia. Contudo, eles favoreceram também o aumento na complexidade das simulações. Como resultado, o custo computacional de simulações complexas de alta fidelidade em engenharia dificultam o uso exclusivo de simulações em otimização. Esta pesquisa de doutorado representa um esforço em combinar técnicas de otimização global e meta-modelagem como uma forma de usar racionalmente os recursos computacionais e aumentar o nível de informação obtida durante a tarefa de otimização. As técnicas mencionadas acima foram usadas na resolução dos problemas contínuo-discretos do projeto ótimo de uma estrutura veicular e componentes estruturais aeronáuticos; identificação de derivadas de controle e estabilidade longitudinal de aviões e modelo não linear de trem de pouso; e melhoramento de meta-modelos via adição de simulações. Além disso, a solução do problema combinatorial do hipercubo latino ótimo também foi implementado. Ao final da pesquisa, a principal lição é que, assim como também acontece com algoritmos clássicos de otimização, o sucesso no uso de métodos heurísticos é altamente dependente do problema...

Managing the long-term persistence of a rare cockatoo under climate change

Harris, J.; Fordham, D.; Mooney, P.; Pedler, L.; Araujo, M.; Paton, D.; Stead, M.; Watts, M.; Akcakaya, H.; Brook, B.
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Publicado em //2012 Português
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1. Linked demographic-bioclimatic models are emerging tools for forecasting climate change impacts on well-studied species, but these methods have been used in few management applications, and species interactions have not been incorporated. We combined population and bioclimatic envelope models to estimate future risks to the viability of a cockatoo population posed by climate change, increased fire frequency, beak-and-feather disease and reduced management. 2. The South Australian glossy black-cockatoo Calyptorhynchus lathami halmaturinus is restricted to Kangaroo Island, Australia, where it numbers 350 birds and is managed intensively. The cockatoo may be at particular risk from climate change because of its insular geographic constraints and specialised diet on a single plant species, Allocasuarina verticillata. The cockatoo population model was parameterised with mark-resight-derived estimates of survival and fecundity from 13 years of demographic data. Species interactions were incorporated by using a climate-change-driven bioclimatic model of Allocasuarina verticillata as a dynamic driver of habitat suitability. A novel application of Latin Hypercube sampling was used to assess the model’s sensitivity to input parameters. 3. Results suggest that unmitigated climate change is likely to be a substantial threat for the cockatoo: all high-CO2-concentration scenarios had expected minimum abundances of <160 birds. Extinction was virtually certain if management of nest-predating brush-tail possums Trichosurus vulpecula was stopped...

Friday 13th failure modelling: a new quantitative risk assessment of UV irradiation for potable water

Davey, K.; Abdul Halim, N.; Lewis, D.
Fonte: Engineers Australia; online Publicador: Engineers Australia; online
Tipo: Conference paper
Publicado em //2012 Português
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UV irradiation is an alternative to widely used chemical disinfection to produce potable water. Failure of a well-run, well-maintained UV plant can lead to catastrophic and enduring public health effects, with or without fatalities. Failure is defined as the unexpected survival of levels of pathogenic Escherichia coli. Friday 13th failure modelling (Fr 13) is an emerging method for new quantitative risk assessments of unexpected failure in process plant due to "within system" chance (stochastic) changes. In this original research a new Fr 13 risk assessment of a simplified unit-operations model for UV irradiation for potable water is presented for the first time. A comparison is made between the predictions from a traditional, single point assessment and Fr 13 model using established UV inactivation kinetics for E. coli. A process risk factor (p) is synthesised in the Fr 13 model and is solved using a refined Monte Carlo simulation with Latin Hypercube sampling. Results reveal that 47 in every 10,000 continuous UV operations can fail unexpectedly with a tolerance of 10% on the design level of reduction in E. coli. This translates, on average, to an unexpected survival of E. coli each 0.58 years of continuous operation. This new insight is not available from traditional assessments...

Assessment of different model-management techniques in history matching problems for reservoir modelling

Sayyafzadeh, M.; Haghighi, M.
Fonte: Australian Petroleum Production and Exploration Association; Australia Publicador: Australian Petroleum Production and Exploration Association; Australia
Tipo: Conference paper
Publicado em //2013 Português
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History matching is a computationally expensive inverse problem. The computation costs are dominantly associated with the optimisation step. Fitness approximation (proxy-modelling) approaches are common methods for reducing computational costs where the time-consuming original fitness function is substituted with an undemanding function known as approximation function (proxy). Almost all of the applied fitness approximation methods in history-matching problems use a similar approach called uncontrolled fitness approximation. It has been corroborated that the uncontrolled fitness approximation approach may mislead the optimisation direction to a wrong optimum point. To prevent this error, it is endorsed that the original function should be utilised along with the approximation function during the optimisation process. To make use of the original function efficiently, a modelmanagement (evolution-control) technique should be applied. There are three different techniques: individual-based, population- based, and adaptive. By using each of these techniques, a controlled fitness approximation approach is assembled, which benefits from online learning. In the first two techniques, the number of original function evaluations in each evolutioncontrol cycle is fixed and predefined...

Erosion modeling in Central China : soil data acquisition by conditioned Latin Hypercube Sampling and incorporation of legacy data; [EGU General Assembly 2013; 07-12 April 2013, Vienna, Austria]

Stumpf, Felix; Schönbrodt-Stitt, Sarah; Schmidt, Karsten; Behrens, Thorsten; Scholten, Thomas
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Artikel
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