Stochastic and Statistical Methods in Hydrology and Environmental Engineering
Optimal operation for Tiete River (Brazil) hydroelectric system composed of six hydroelectric pla... more Optimal operation for Tiete River (Brazil) hydroelectric system composed of six hydroelectric plants is studied to characterize its stochastic aspects via dynamic programming. The optimization problem is expressed as the minimization of expected value of energy required to meet local demand for different periods of operation discretized in trimesters. The stochastic process of occurence of natural river discharge is represented by 4th order multivariate autoregressive model. Problem solution is obtained by Stochastic Dual Dynamic Programming (SSDP) via Benders1 decomposition as proposed by Pereira and Pinto (1985, 1988) which incorporates hydrologic variability admitting multiple equally likely future flow scenarios at each stage. Repeated optimizations are made with independent flow sequences to evaluate the importance of the number of flow scenarios in a tree-like structure of synthetic hydrologic inputs and the period of operation as regards the variability of the expected value of the energy import costs for optimal operation.
A operacao de uma unidade de filtracao numa estacao de tratamento de agua requer numerosas deciso... more A operacao de uma unidade de filtracao numa estacao de tratamento de agua requer numerosas decisoes com profundas consequencias economicas. Os projetos de unidades de filtracao que explicam a maior parte dos custos de investimento para esas estacoes requerem uma metodologia que considere os diversos aspectos dos procesos e da operacao de uma maneira abrangente. Esta pesquisa aproxima o projeto de filtro rapido de areia pelo criterio de minimizacao do custos de filtracao. Tres pasos distintos foram seguidos para obter o projeto otimo. Funcoes tecnologicas baseadas em um modelo matematico de filtracao em forma de equacoes diferenciais parciais foram desenvolvidas e uma funcao de custo estabelecida para quatro "lay-outs" de filtros. O problema do projeto foi finalmente expreso como o de minimizacao irrestrita da funcao de custo nao linear em termos de seis variaveis de decisao e repetidamente resolvida pelo algoritmo quase-Newton. A solucao otimizada para as variaveis de deci...
Um dos elementos mais importantes no projeto de obras de drenagem urbana para o controle de cheia... more Um dos elementos mais importantes no projeto de obras de drenagem urbana para o controle de cheias é a intensidade máxima média de precipitação para dada duração e probabilidade anual. Tipicamente, essa informação é apresentada no formato de Curvas de Intensidade - Duração e Frequência (IDF). Porém a frequente ausência de séries extensas de precipitação leva à necessidade de extrapolações estatísticas via distribuições teóricas de probabilidade. Decidir qual é a melhor distribuição de probabilidade que explique as observações e permita a extrapolação para maiores tempos de retorno depende das observações de precipitação e de sua qualidade. Desse modo, o objetivo desse artigo é avaliar via análises estatísticas (Coeficiente de Determinação) não paramétricas (teste de Kolmogorov-Smirnov e P-Valor) e visuais as melhores combinações entre os métodos de avaliação de frequência empíricos (Weibull, Mediana, Hosking, Blow, Cunnane, Gringorten, Hazen, Tukey’s e Chegodayev’s) e teóricos (Gumb...
Healthcare Waste (HW) management in Brazil has been discussed since last years, mainly by RDC 306... more Healthcare Waste (HW) management in Brazil has been discussed since last years, mainly by RDC 306/2004 and Resolution Conama 358/2005, which laws require improvements in all stages of this management (segregation, internal collection and packaging, external transport and storage ), and give the responsibility of these wastes to theirs generators. The city of Sao Carlos produce, monthly, about 20 tonnes of HW and, approximately, 50% come from Santa Casa of Sao Carlos. The management of the realized procedures in this hospital was never evaluated until now considering performance improvement. Investigated methods pointed to some applications using performance indicators and these can be evaluated by Factorial Analyses (FA) and Analytic Hierarchy Process (AHP). A framework of interview was elaborated containing 29 qualitative observation variables, which questions were applied to 98 employers in this hospital. The obtained information were associated a different scales of response, acc...
Shop ASCE; MyASCE; Donate Now; Contact Us; About Civil Engineering; About ASCE. ASCE Join Now. Kn... more Shop ASCE; MyASCE; Donate Now; Contact Us; About Civil Engineering; About ASCE. ASCE Join Now. Knowledge & Learning: Books & Journals; CE Body of Knowledge; Certification; Codes & Standards; Conferences; Continuing ...
Water supply systems are large consumers of energy, and a reduction is one of the factors most de... more Water supply systems are large consumers of energy, and a reduction is one of the factors most desired by their managers and the use of hybrid systems for energy production was a new proposes that group the reduction of energy consumption from the national network and the production of more “green” energy. This work presents a computational model based on neural networks to determine the best configuration of a hybrid system to generate energy, to be applied to a typical water supply. The components of the energy used to make this hybrid system are the national power grid, micro-hydro and wind turbines. The artificial neural network is composed of six layers, trained using data generated by a model of hybrid configuration and economic simulator – CES (e.g. HOMER). The reason for the development of an advanced model of forecasting based on neural networks is to allow rapid simulation and proper interaction with hydraulic and power model simulator – HPS (e.g. EPANET). The results show...
Stochastic and Statistical Methods in Hydrology and Environmental Engineering
Optimal operation for Tiete River (Brazil) hydroelectric system composed of six hydroelectric pla... more Optimal operation for Tiete River (Brazil) hydroelectric system composed of six hydroelectric plants is studied to characterize its stochastic aspects via dynamic programming. The optimization problem is expressed as the minimization of expected value of energy required to meet local demand for different periods of operation discretized in trimesters. The stochastic process of occurence of natural river discharge is represented by 4th order multivariate autoregressive model. Problem solution is obtained by Stochastic Dual Dynamic Programming (SSDP) via Benders1 decomposition as proposed by Pereira and Pinto (1985, 1988) which incorporates hydrologic variability admitting multiple equally likely future flow scenarios at each stage. Repeated optimizations are made with independent flow sequences to evaluate the importance of the number of flow scenarios in a tree-like structure of synthetic hydrologic inputs and the period of operation as regards the variability of the expected value of the energy import costs for optimal operation.
A operacao de uma unidade de filtracao numa estacao de tratamento de agua requer numerosas deciso... more A operacao de uma unidade de filtracao numa estacao de tratamento de agua requer numerosas decisoes com profundas consequencias economicas. Os projetos de unidades de filtracao que explicam a maior parte dos custos de investimento para esas estacoes requerem uma metodologia que considere os diversos aspectos dos procesos e da operacao de uma maneira abrangente. Esta pesquisa aproxima o projeto de filtro rapido de areia pelo criterio de minimizacao do custos de filtracao. Tres pasos distintos foram seguidos para obter o projeto otimo. Funcoes tecnologicas baseadas em um modelo matematico de filtracao em forma de equacoes diferenciais parciais foram desenvolvidas e uma funcao de custo estabelecida para quatro "lay-outs" de filtros. O problema do projeto foi finalmente expreso como o de minimizacao irrestrita da funcao de custo nao linear em termos de seis variaveis de decisao e repetidamente resolvida pelo algoritmo quase-Newton. A solucao otimizada para as variaveis de deci...
Um dos elementos mais importantes no projeto de obras de drenagem urbana para o controle de cheia... more Um dos elementos mais importantes no projeto de obras de drenagem urbana para o controle de cheias é a intensidade máxima média de precipitação para dada duração e probabilidade anual. Tipicamente, essa informação é apresentada no formato de Curvas de Intensidade - Duração e Frequência (IDF). Porém a frequente ausência de séries extensas de precipitação leva à necessidade de extrapolações estatísticas via distribuições teóricas de probabilidade. Decidir qual é a melhor distribuição de probabilidade que explique as observações e permita a extrapolação para maiores tempos de retorno depende das observações de precipitação e de sua qualidade. Desse modo, o objetivo desse artigo é avaliar via análises estatísticas (Coeficiente de Determinação) não paramétricas (teste de Kolmogorov-Smirnov e P-Valor) e visuais as melhores combinações entre os métodos de avaliação de frequência empíricos (Weibull, Mediana, Hosking, Blow, Cunnane, Gringorten, Hazen, Tukey’s e Chegodayev’s) e teóricos (Gumb...
Healthcare Waste (HW) management in Brazil has been discussed since last years, mainly by RDC 306... more Healthcare Waste (HW) management in Brazil has been discussed since last years, mainly by RDC 306/2004 and Resolution Conama 358/2005, which laws require improvements in all stages of this management (segregation, internal collection and packaging, external transport and storage ), and give the responsibility of these wastes to theirs generators. The city of Sao Carlos produce, monthly, about 20 tonnes of HW and, approximately, 50% come from Santa Casa of Sao Carlos. The management of the realized procedures in this hospital was never evaluated until now considering performance improvement. Investigated methods pointed to some applications using performance indicators and these can be evaluated by Factorial Analyses (FA) and Analytic Hierarchy Process (AHP). A framework of interview was elaborated containing 29 qualitative observation variables, which questions were applied to 98 employers in this hospital. The obtained information were associated a different scales of response, acc...
Shop ASCE; MyASCE; Donate Now; Contact Us; About Civil Engineering; About ASCE. ASCE Join Now. Kn... more Shop ASCE; MyASCE; Donate Now; Contact Us; About Civil Engineering; About ASCE. ASCE Join Now. Knowledge & Learning: Books & Journals; CE Body of Knowledge; Certification; Codes & Standards; Conferences; Continuing ...
Water supply systems are large consumers of energy, and a reduction is one of the factors most de... more Water supply systems are large consumers of energy, and a reduction is one of the factors most desired by their managers and the use of hybrid systems for energy production was a new proposes that group the reduction of energy consumption from the national network and the production of more “green” energy. This work presents a computational model based on neural networks to determine the best configuration of a hybrid system to generate energy, to be applied to a typical water supply. The components of the energy used to make this hybrid system are the national power grid, micro-hydro and wind turbines. The artificial neural network is composed of six layers, trained using data generated by a model of hybrid configuration and economic simulator – CES (e.g. HOMER). The reason for the development of an advanced model of forecasting based on neural networks is to allow rapid simulation and proper interaction with hydraulic and power model simulator – HPS (e.g. EPANET). The results show...
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Papers by Luisa Fernanda Ribeiro Reis