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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Toward a general curvilinear model for nearly-horizontal flows in two horizontal dimensions

Rodenhuis, G. S. January 1984 (has links)
No description available.
2

Investigation on the use of raw time series and artificial neural networks for flow pattern identification in pipelines

Goudinakis, George 03 1900 (has links)
A new methodology was developed for flow regime identification in pipes. The method utilizes the pattern recognition abilities of Artificial Neural Networks and the unprocessed time series of a system-monitoring-signal. The methodology was tested with synthetic data from a conceptual system, liquid level indicating Capacitance signals from a Horizontal flow system and with a pressure difference signal from a S-shape riser. The results showed that the signals that were generated for the conceptual system had all their patterns identified correctly with no errors what so ever. The patterns for the Horizontal flow system were also classified very well with a few errors recorded due to original misclassifications of the data. The misclassifications were mainly due to subjectivity and due to signals that belonged to transition regions, hence a single label for them was not adequate. Finally the results for the S-shape riser showed also good agreement with the visual observations and the few errors that were identified were again due to original misclassifications but also to the lack of long enough time series for some flow cases and the availability of less flow cases for some flow regimes than others. In general the methodology proved to be successful and there were a number of advantages identified for this neural network methodology in comparison to other ones and especially the feature extraction methods. These advantages were: Faster identification of changes to the condition of the system, inexpensive suitable for a variety of pipeline geometries and more powerful on the flow regime identification, even for transitional cases.
3

Investigation on the use of raw time series and artificial neural networks for flow pattern identification in pipelines

Goudinakis, George January 2004 (has links)
A new methodology was developed for flow regime identification in pipes. The method utilizes the pattern recognition abilities of Artificial Neural Networks and the unprocessed time series of a system-monitoring-signal. The methodology was tested with synthetic data from a conceptual system, liquid level indicating capacitance signals from a Horizontal flow system and with a pressure difference signal from a S-shape riser. The results showed that the signals that were generated for the conceptual system had all their patterns identified correctly with no errors whatsoever. The patterns for the Horizontal flow system were also classified very well with a few errors recorded due to original misclassifications of the data. The misclassifications were mainly due to subjectivity and due to signals that belonged to transition regions, hence a single label for them was not adequate. Finally the results for the S-shape riser showed also good agreement with the visual observations and the few errors that were identified were again due to original misclassifications but also to the lack of long enough time series for some flow cases and the availability of less flow cases for some flow regimes than others. In general the methodology proved to be successful and there were a number of advantages identified for this neural network methodology in comparison to other ones and especially the feature extraction methods. These advantages were: Faster identfication of changes to the condition of the system, inexpensive suitable for a variety of pipeline geometries and more powerful on the flow regime identification, even for transitional cases.
4

Study of Mechanisms of Secondarily Treated Sewage and Textile Wastewater by Hybrid Constructed Wetlands

Chuang, Hsiao-hui 13 February 2009 (has links)
The aim of this investigation was to use hybrid constructed wetlands to treat the secondary effluents from NSYSU campus sewage treatment plant, which had high phosphate and ammonium nitogen and from a textile industrial wastewater treatment plant, which had high chemical oxygen demand(COD) . The purpose of this study is to design optimum operation, conditions and to select suitable types of filter media through optimum combinations of vertical flow (VF) and horizontal flow (HF) constructed wetland systems. The flow regimes for vertical flow operation in this study include continuous flow with filled water, trickling filter type and batch type, while the flow types for horizontal flow operation include high water level and low water level effluents. The experimental of results showed that the best ammonium nitrogen removal efficiency was found in trickling filter type, which was because high oxygen was provided under this flow pattern creating a suitable condition for nitrification , especially in V3 column(39.09%), while the best denitrification effect was fonnd in low water level horizontal operation, especially in H2 bed(42.56%). The experimental results of treating the Everest effluent from the wastewater treatment plant showed that the flow regime in V3 system had best removal of COD in batch type. In trickling filter and low water level type, the optimum hybrid of V3+H3 had the COD removal efficiency eqail to(33.3%)+(49.8%) respectirely .For the experimental results of tolerance of macrophyte, Hedycbium coronarium Koenig live well, but no significant removal efficiencies of nutrient was fund.
5

Viabilidade técnica do emprego de sistemas tipo \"wetlands\" para tratamento de água cinza visando o reúso não potável. / Technical feasibility of employment of systems type \"wetlands\" for greywater treatment aiming reuse no potable.

Monteiro, Rodrigo Cesar de Moraes 03 August 2009 (has links)
A disparidade entre o crescimento populacional e a oferta de água potável apresenta grandes riscos de abastecimento em grandes centros urbanos. A utilização desse recurso em residências é diferenciada em uso potável e não potável. A utilização de água potável para finalidades menos nobres leva à escassez hídrica local em menor prazo, necessitando de busca de água cada vez mais longe, encarecendo o valor desse bem aos usuários. O uso não potável deveria ser suprido por fontes alternativas, como águas pluviais ou água de reúso. Em residências, muitas vezes o volume de água não potável é suprido pela produção de água cinza, necessitando de tratamento para que seu uso não ofereça riscos aos usuários. Sistemas de tratamento tipo wetlands podem ser uma alternativa economicamente viável em locais com disponibilidade de área, tendo como atrativos a independência de energia elétrica para o processo, ausência da necessidade de produtos químicos e forte apelo estético e ambiental. O presente trabalho visou avaliar a viabilidade técnica de sistemas tipo wetlands no tratamento de água cinza, determinando a remoção de material orgânico, a constante de remoção desse substrato, determinar as taxas de remoções de nitrogênio e fósforo e avaliar a eficiência na remoção de indicadores de contaminação fecal em um sistema tipo wetlands de fluxo subsuperficial horizontal cultivado em policultura. O sistema tipo wetlands apresentou remoção média de matéria orgânica próxima a 60% nos para os parâmetros DBO, DQO e COT, possibilitando: K20 DBO = 0,40; K20 DQO = 0,34; e K20 COT 0,30. As taxas de remoção de nutriente foram: 0,07g/m².d de fósforo total e 0,22g/m².d de nitrogênio kjeldahl total. A remoção média de indicadores de contaminação fecal foi de 56% para coliformes totais e uma média de 2,7x104 UFC/100mL e 94% para Escherichia coli com média de 4,6x101 UFC/100mL no efluente final. O efluente final do sistema tipo wetlands apresenta melhora na sua qualidade. / The disparity between population growth and supply of drinking water presents major risks to supply in large urban centers. The use of this feature in homes is different in non-potable and potable use. The use of drinking water for less noble purposes leads to local water shortages in less time, requiring the search of water each time further, the value of this expensive and users. The non-potable use should be supplied by alternative sources such as rainwater or water reuse. In homes, many times the volume of non-potable water is supplied by production of greywater, requiring treatment for their use does not offer risks to users. Systems of treatment like \"wetlands\" may be an economically viable alternative in locations where the availability of area, with attractions such as the independence of electric energy to the process, no need for chemicals and strong aesthetic appeal and environmental. This study aimed to evaluate the technical feasibility of such systems \"wetlands\" in the treatment of gray water, determining the removal of organic material, the constant removal of the substrate, determining the rates of removal of nitrogen and phosphorus and evaluate the efficiency in the removal of indicators of fecal contamination in a system like \"wetlands\" of horizontal subsurface flow grown in polyculture. The system type \"wetlands\" showed average removal of organic matter close to 60% in for the parameters BOD, COD and TOC, allowing: DBO K20 = 0.40; K20 DQO = 0.34 and K20 TOC 0.30. The rates of removal of nutrients were: 0.07 g / m².d of total phosphorus, and 0.22 g / m².d of total Kjeldahl nitrogen. The average removal of indicators of fecal contamination was 56% for total coliforms and an average of 2.7x104CFU/100mL and 94% for Escherichia coli with an average of 4.6x101CFU/100mL in the final effluent. The effluent end of the system as \"wetlands\" has improved its quality.
6

Viabilidade técnica do emprego de sistemas tipo \"wetlands\" para tratamento de água cinza visando o reúso não potável. / Technical feasibility of employment of systems type \"wetlands\" for greywater treatment aiming reuse no potable.

Rodrigo Cesar de Moraes Monteiro 03 August 2009 (has links)
A disparidade entre o crescimento populacional e a oferta de água potável apresenta grandes riscos de abastecimento em grandes centros urbanos. A utilização desse recurso em residências é diferenciada em uso potável e não potável. A utilização de água potável para finalidades menos nobres leva à escassez hídrica local em menor prazo, necessitando de busca de água cada vez mais longe, encarecendo o valor desse bem aos usuários. O uso não potável deveria ser suprido por fontes alternativas, como águas pluviais ou água de reúso. Em residências, muitas vezes o volume de água não potável é suprido pela produção de água cinza, necessitando de tratamento para que seu uso não ofereça riscos aos usuários. Sistemas de tratamento tipo wetlands podem ser uma alternativa economicamente viável em locais com disponibilidade de área, tendo como atrativos a independência de energia elétrica para o processo, ausência da necessidade de produtos químicos e forte apelo estético e ambiental. O presente trabalho visou avaliar a viabilidade técnica de sistemas tipo wetlands no tratamento de água cinza, determinando a remoção de material orgânico, a constante de remoção desse substrato, determinar as taxas de remoções de nitrogênio e fósforo e avaliar a eficiência na remoção de indicadores de contaminação fecal em um sistema tipo wetlands de fluxo subsuperficial horizontal cultivado em policultura. O sistema tipo wetlands apresentou remoção média de matéria orgânica próxima a 60% nos para os parâmetros DBO, DQO e COT, possibilitando: K20 DBO = 0,40; K20 DQO = 0,34; e K20 COT 0,30. As taxas de remoção de nutriente foram: 0,07g/m².d de fósforo total e 0,22g/m².d de nitrogênio kjeldahl total. A remoção média de indicadores de contaminação fecal foi de 56% para coliformes totais e uma média de 2,7x104 UFC/100mL e 94% para Escherichia coli com média de 4,6x101 UFC/100mL no efluente final. O efluente final do sistema tipo wetlands apresenta melhora na sua qualidade. / The disparity between population growth and supply of drinking water presents major risks to supply in large urban centers. The use of this feature in homes is different in non-potable and potable use. The use of drinking water for less noble purposes leads to local water shortages in less time, requiring the search of water each time further, the value of this expensive and users. The non-potable use should be supplied by alternative sources such as rainwater or water reuse. In homes, many times the volume of non-potable water is supplied by production of greywater, requiring treatment for their use does not offer risks to users. Systems of treatment like \"wetlands\" may be an economically viable alternative in locations where the availability of area, with attractions such as the independence of electric energy to the process, no need for chemicals and strong aesthetic appeal and environmental. This study aimed to evaluate the technical feasibility of such systems \"wetlands\" in the treatment of gray water, determining the removal of organic material, the constant removal of the substrate, determining the rates of removal of nitrogen and phosphorus and evaluate the efficiency in the removal of indicators of fecal contamination in a system like \"wetlands\" of horizontal subsurface flow grown in polyculture. The system type \"wetlands\" showed average removal of organic matter close to 60% in for the parameters BOD, COD and TOC, allowing: DBO K20 = 0.40; K20 DQO = 0.34 and K20 TOC 0.30. The rates of removal of nutrients were: 0.07 g / m².d of total phosphorus, and 0.22 g / m².d of total Kjeldahl nitrogen. The average removal of indicators of fecal contamination was 56% for total coliforms and an average of 2.7x104CFU/100mL and 94% for Escherichia coli with an average of 4.6x101CFU/100mL in the final effluent. The effluent end of the system as \"wetlands\" has improved its quality.
7

Avaliação da degradação e toxicidade de formaldeído em reator anaeróbio horizontal de leito fixo / Evaluation of formaldehyde degradation and toxicity in horizontal-flow anaerobic immobilized sludge reactor

Oliveira, Sonia Valle Walter Borges de 25 May 2001 (has links)
Para minimizar os impactos ambientais causados pelo lançamento de formaldeído na natureza, é importante o desenvolvimento de tecnologias adequadas para o seu tratamento. Sistemas aeróbios têm sido utilizados, porém, as opções por tratamento anaeróbio estão tendo cada vez mais aceitação, principalmente pelo baixo consumo de energia e baixa produção de lodo. Por outro lado, substâncias tóxicas podem provocar distúrbios em reatores anaeróbios. Algumas pesquisas já foram desenvolvidas quanto ao tratamento biológico anaeróbio de formaldeído, no entanto, ainda não se chegou a um consenso sobre o seu comportamento ou qual o sistema mais eficaz. Nesse trabalho, avaliou-se a degradação e a toxicidade dessa substância em reator anaeróbio horizontal de leito fixo, a fim de trazer subsídios para essa questão. As concentrações de estudo variaram de, aproximadamente, 30 a 1500 mg/L de formaldeído, atingindo-se as eficiências de remoção de até 99,7 % de formaldeído e 92 % de DQO. A presença de ácidos graxos com até cinco carbonos durante a degradação do formaldeído pode indicar uma rota de degradação diferente da sugerida na literatura, onde os produtos intermediários seriam o metanol e o ácido fórmico. O modelo cinético de Monod foi o que melhor representou os dados experimentais, com \'R IND.max\' POT.app\' = 2,79 x \'10 POT.-3\' HCHO/mg SSV.h e \'K IND.S\' POT. app\' = 242,8 mg HCHO/L. / In order to minimize the environmental impacts caused by formaldehyde discharge in the nature, the development of appropriate technologies for its treatment is important. Aerobic systems have been used, however, anaerobic treatment options have been widely studied, mainly due to low energy consumption and sludge production. On the other hand, toxic substances can lead to disturbances in anaerobic reactors. Some formaldehyde anaerobic biological treatment researches have already been developed, although, there is no consensus about its behavior or which is the most efficient system. Degradation and toxicity of this substance were evaluated in horizontal-flow anaerobic immobilized sludge reactor, with the purpose of producing subsidies for this issue. Formaldehyde concentrations ranging from, approximately, 30 to 1500 mg/L were applied in the reactor and formaldehyde and COD removal efficiencies of 99,7% e 92% were achieved, respectively. Volatile fatty acids with up to 5 carbons, found during the formaldehyde degradation, can indicate that degradation followed different routes than those suggested in the literature, that reports the formation of intermediates such as methanol and formic acid. Monod kinetic model fitted well the experimental data, with apparent kinetic parameters estimated as \'R IND.max\' POT. app\' = 2,79 x \'10 POT.-3\' mg HCHO/mg SSV.h and \'K IND.S\' POT. app\' = 242,8 mg HCHO/L.
8

Modélisation et simulation de la dispersion turbulente et du dépôt de gouttes dans un canal horizontal / Modeling of the droplets turbulent dispersion and deposition in a horizontal channel

Neiss, Coraline 03 October 2013 (has links)
Ce travail de thèse est consacré à l'étude des écoulements diphasiques dispersés turbulents gaz/gouttes et plus particulièrement à la modélisation du phénomène de dépôt de gouttes en canal horizontal, dont la compréhension et la prédiction sont essentielles pour de nombreuses applications industrielles. Les gouttes sont supposées de taille plus petite que les échelles de longueur caractéristiques de l'écoulement de gaz turbulent, avec une masse volumique grande devant celle de la phase continue, les forces qui agissent sur les gouttes se limitent ainsi à la traînée, à la poussée d'Archimède et à la gravité. Le taux de présence de la phase dispersée est suffisamment important pour tenir compte de l'influence des gouttes sur la turbulence du gaz (couplage à deux sens), mais suffisamment faible pour pouvoir négliger les collisions entre les gouttes. En écoulement horizontal, le dépôt des gouttes en paroi est piloté par deux mécanismes principaux qui agissent en parallèle : la gravité et la diffusion turbulente/vol libre. Cette physique du dépôt est déclinée en deux volets, avec une première étude à l'échelle 3D locale et une seconde étude à l'échelle système 1D. Dans chacune de ces approches, un modèle pour la vitesse de dépôt de gouttes en paroi est développé, puis validé par comparaison à des données expérimentales. Le modèle de dépôt local, établi sous l'hypothèse d'un film liquide infiniment mince et absorbant, est implanté dans le code de simulation numérique NEPTUNE_CFD, puis validé par comparaison aux données expérimentales de Namie & Ueda, qui étudient le dépôt des gouttes en canal horizontal. Une analyse des équations de transport des principales grandeurs moyennes de l'écoulement, ainsi que des transferts d'énergies entre phases, est menée afin de mettre en évidence les phénomènes de couplage et leurs influences sur la turbulence de la phase continue. Le modèle unidimensionnel, développé dans le cadre d'un besoin industriel, est implanté dans le code CATHARE-3 et est confronté aux données de l'expérience REGARD du CEA Grenoble. / Droplets dispersion and deposition in turbulent duct flows are important processes, occurring in numerous environmental and industrial applications. This work is devoted to the study of gas-droplets flows and, more particularly, the objective is to improve the droplets deposition modeling in horizontal flows. Droplets are supposed to be smaller than the Kolmogorov scale, with a density large compared to the density of the gas phase. Under these assumptions, the motion of a droplet is considered to be governed by the drag force, the buoyancy force, and the gravity. Dilute incompressible and isothermal gas-droplets flows are studied, so inter-particle collisions are neglected but two-way coupling is retained, which means that modulation of turbulence by the particles is accounted for. In horizontal flow, droplets reach the wall under the actions of the gravitational settling and the turbulent diffusion. Two approaches will be used in developing this deposition physics with a first study at the 3D local scale and a second one at the 1D scale, realized for an industrial need. For each case, a model is developed for the mean deposition velocity of the droplets, with is implemented in a numerical simulation tool and then validated by comparison to experimental data. The local deposition model is established under the assumptions that the liquid film is extremely thin and perfectly absorbing and is implemented in the Neptune_CFD code. The experience carried out by Namie & Ueda, which consist in small droplets deposition from a turbulent dispersed flow in a horizontal rectangular duct, is simulated. An analysis of the interphase transfer terms in the kinetic energy equations shows the interactions between the dispersed phase and the continuous one and the impact of these phenomena on the turbulence of the gas phase is pointed out. The 1D deposition model is developed for the CATHARE-3 code and experimental data from the REGARD facility of the CEA Grenoble are used for validation.
9

Avaliação da degradação e toxicidade de formaldeído em reator anaeróbio horizontal de leito fixo / Evaluation of formaldehyde degradation and toxicity in horizontal-flow anaerobic immobilized sludge reactor

Sonia Valle Walter Borges de Oliveira 25 May 2001 (has links)
Para minimizar os impactos ambientais causados pelo lançamento de formaldeído na natureza, é importante o desenvolvimento de tecnologias adequadas para o seu tratamento. Sistemas aeróbios têm sido utilizados, porém, as opções por tratamento anaeróbio estão tendo cada vez mais aceitação, principalmente pelo baixo consumo de energia e baixa produção de lodo. Por outro lado, substâncias tóxicas podem provocar distúrbios em reatores anaeróbios. Algumas pesquisas já foram desenvolvidas quanto ao tratamento biológico anaeróbio de formaldeído, no entanto, ainda não se chegou a um consenso sobre o seu comportamento ou qual o sistema mais eficaz. Nesse trabalho, avaliou-se a degradação e a toxicidade dessa substância em reator anaeróbio horizontal de leito fixo, a fim de trazer subsídios para essa questão. As concentrações de estudo variaram de, aproximadamente, 30 a 1500 mg/L de formaldeído, atingindo-se as eficiências de remoção de até 99,7 % de formaldeído e 92 % de DQO. A presença de ácidos graxos com até cinco carbonos durante a degradação do formaldeído pode indicar uma rota de degradação diferente da sugerida na literatura, onde os produtos intermediários seriam o metanol e o ácido fórmico. O modelo cinético de Monod foi o que melhor representou os dados experimentais, com \'R IND.max\' POT.app\' = 2,79 x \'10 POT.-3\' HCHO/mg SSV.h e \'K IND.S\' POT. app\' = 242,8 mg HCHO/L. / In order to minimize the environmental impacts caused by formaldehyde discharge in the nature, the development of appropriate technologies for its treatment is important. Aerobic systems have been used, however, anaerobic treatment options have been widely studied, mainly due to low energy consumption and sludge production. On the other hand, toxic substances can lead to disturbances in anaerobic reactors. Some formaldehyde anaerobic biological treatment researches have already been developed, although, there is no consensus about its behavior or which is the most efficient system. Degradation and toxicity of this substance were evaluated in horizontal-flow anaerobic immobilized sludge reactor, with the purpose of producing subsidies for this issue. Formaldehyde concentrations ranging from, approximately, 30 to 1500 mg/L were applied in the reactor and formaldehyde and COD removal efficiencies of 99,7% e 92% were achieved, respectively. Volatile fatty acids with up to 5 carbons, found during the formaldehyde degradation, can indicate that degradation followed different routes than those suggested in the literature, that reports the formation of intermediates such as methanol and formic acid. Monod kinetic model fitted well the experimental data, with apparent kinetic parameters estimated as \'R IND.max\' POT. app\' = 2,79 x \'10 POT.-3\' mg HCHO/mg SSV.h and \'K IND.S\' POT. app\' = 242,8 mg HCHO/L.
10

Výzkum technologie vícestupňového filtračního systému kořenové čistírny / Research of the Multistage Constructed Treatment Wetlands Technology

Chaloupka, Ondřej January 2019 (has links)
The ways of purifying waste water produced by human society are nowadays a great deal. With the increasing pressure on sustainable construction, technology using principles close to natural processes are at the forefront. Treatment wetlands have been in use for almost 30 years and thanks mainly to developments abroad, they prove they are a suitable option for smaller producers of pollution. When designing a treatment wetland for municipalities with a larger amount of inhabitants, it is necessary to modify the proposal in order to eliminate all types of pollution. This thesis therefore compares three sewage treatment plants with a multistage filtration system. Comparing the achieved parameters will be beneficial for defining the rules for optimal design of these types of wastewater treatment plant.

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