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Dissertations / Theses on the topic 'Rats in the Ranks'

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Published: 4 June 2021
Last updated: 28 January 2023

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1

Lima, Mariana dos Reis. "Effect of calendula officinalis in rats submitted to experimental periodontitis: participation of RANK-RANKL-OPG and WNT / Β-CATENIN PATHWAYS." Universidade Federal do CearÃ, 2016. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=18394.

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FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico
Periodontitis is an infecto-inflammatory disease that leads to connective tissue and alveolar bone loss. Calendula officinalis (CLO) has been used due to its anti-inflammatory effects. Therefore the aim of this study was to evaluate the effect of CLO on alveolar bone loss (ABL) in rats focusing on RANK-RANKL-OPG and WNT signaling pathways. Experimental periodontitis (EP) was induced through placement of a nylon ligature around the upper left 2nd molar, and the hemimaxilla used as control. The animals were divided in groups: Normal, subjected to no treatment; Saline (SAL), that received 2 ml/kg of 0,9% saline solution orally; or CLO at 90 mg/kg orally, 30 minutes before EP and daily for 11 days until euthanasia. In order to evaluate the periodontal tissue, it macroscopic, micro-tomographic, electron scanning microscopy (SEM), confocal microscopy and polarized light microscopy analyses were performed, as well as immunohistochemistry for WNT 10b, β-catenin, DKK-1, RANK, RANKL, and OPG. During euthanasia the gingival tissue was removed for malonaldehyde (MDA) assay. Treatment with CLO significantly prevented ABL, preserved bone internal microstructure (p<0.05) and topography, and also preserved collagen fibers from the periodontal ligament, when compared to SAL. CLO significantly increased the number of immunopositive cells for WNT 10b, β-catenin and OPG and reduced DKK-1, RANK (p>0.05) and RANKL. CLO reduced the gingival levels of MDA compared to SAL (p<0.05). In this way, we can conclude that CLO prevented ABL via RANK-RANKL-OPG and WNT signaling pathway.
A periodontite à uma doenÃa infecto-inflamatÃria que causa perda de tecido conjuntivo e osso alveolar. A Calendula officinalis (CLO) tem sido utilizada pelos seus efeitos anti-inflamatÃrios. Nesse contexto, o objetivo deste trabalho foi avaliar efeito da CLO na perda Ãssea alveolar (POA) em ratos com foco na participaÃÃo do eixo RANK-RANKL-OPG e da via WNT/β-catenina. A periodontite experimental (PE) foi induzida atravÃs da inserÃÃo do fio (nailon 3.0) em torno do 2 molar superior esquerdo, e hemiarcada contralateral usada como controle. Os animais foram divididos em grupos: Normal, nÃo submetido a nenhum procedimento; Salina (SAL), que receberam 2 ml/kg de soluÃÃo salina 0,9% - v.o.; ou CLO na dose de 90 mg/kg - v.o. 30 min antes da PE e diariamente durante por 11 dias atà eutanÃsia. Para avaliaÃÃo do tecido periodontal realizaram-se anÃlises macroscÃpica, por microtomografia computadorizada, por microscopia eletrÃnica de varredura (MEV), microscopia confocal e microscopia por luz polarizada, imunohistoquÃmica para WNT 10b, β-catenina, DKK-1, RANK, RANKL e OPG. Por ocasiÃo da eutanÃsia foi removido tecido gengival para avaliaÃÃo dos nÃveis de malondialdeÃdo (MDA). O tratamento com CLO preveniu de forma significante a POA, preservou a microestrutura interna (p<0,05) e topografia do tecido Ãsseo, e preservou tambÃm as fibras colÃgenas do ligamento periodontal, quando comparado a SAL. A CLO provocou aumento significante de cÃlulas imunopositivas para WNT 10b, β-catenina e OPG e reduÃÃo na imunomarcaÃÃo de DKK-1, RANK (p>0,05) e RANKL. CLO reduziu os nÃveis de MDA gengivais comparados a SAL (p<0,05). Desta forma, podemos concluir que a CLO previne a POA com participaÃÃo do eixo RANK-RANKL-OPG e da via WNT/β-catenina.
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2

Valente, Fabrício Luciani. "Histomorfometria e expressão imunoistoquímica de RANKL em fêmur e vértebra de ratos com osteoporose secundária." Universidade Federal de Viçosa, 2007. http://locus.ufv.br/handle/123456789/4972.

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Osteoporosis is a common human disease affecting both men and women, and it can classified as (1) primary, related to sexual hormones deficiency or senility, or (2) secondary, for what the most common example is the chronic therapies with glucocorticoids. Whatever is its cause, the osteoporosis outcomes are bone loss and increased fracture risk. Although osteoporosis is considered a systemic condition, bone loss seen in osteoporosis is not homogeneous throughout the skeleton. RANKL is a cytokine able to activate the osteoclasts function and its expression is inducible in osteoblasts and T cells by a range of stimuli. Function of RANKL has been considered a possible therapeutic target for the treatment of osteoporosis. To evaluate the trabecular bone loss related to the RANKL expression, immunochemistry and histomorphometric assays were used in femur and vertebra of castrated and/or glucocorticoid-treated male and female rats, at the day 56 after induction. RANKL expression was evident only in the castrated group, both male and female, but not in the group of castrated rats that also received glucocorticoid therapy. But histomorphometric data showed that bone loss was similar in both groups. That could happen because glucocorticoid can inhibit osteoblast metabolism. Histomorphometry also reveals that trabecular bone mass in male is similar to female, and bone loss is not homogenous between distal and proximal femur and vertebra body. At the day 56 after induction, bone loss, in femur and vertebra, both male and female, was compatible to osteoporosis.
A osteoporose é uma doença comum em humanos, acometendo tanto mulheres quanto homens. A doença pode ter origem primária, relacionada à deficiência de hormônios sexuais ou a senilidade, ou secundária, cujo exemplo mais comum é o uso crônico de glicocorticóides. Independente da causa, a conseqüência da osteoporose é a diminuição da massa óssea, aumentando o risco de fraturas. Apesar de ser considerada uma doença sistêmica, a redução de massa óssea na osteoporose não é uniforme no esqueleto. RANKL é uma citocina capaz de ativar a função osteoclástica e sua expressão é indutível em osteoblastos e linfócitos T. A função desta citocina tem sido considerada um possível alvo terapêutico no tratamento da osteoporose. Para avaliar a relação da perda óssea trabecular e a expressão de RANKL, foram realizados testes imunoistoquímicos e histomorfométricos em fêmur e vértebras de ratos castrados e/ou tratados com glicocorticóides, 56 dias após a indução. A expressão imunoistoquímica de RANKL pôde ser verificada nos animais castrados, tanto machos quanto fêmeas, mas não no grupo castrado que também recebeu glicocorticóide. Entretanto, a diminuição da massa óssea em ambos os grupos foi similar na avaliação histomorfométrica. Isso pode ocorrer por causa do efeito inibitório que os glicocorticóides têm sobre o metabolismo. As análises histomorfométricas revelaram ainda, que a massa óssea trabecular avaliada por este método é similar em machos e fêmeas, e que a perda óssea não é uniforme entre o colo femoral, o côndilo femoral e o corpo vertebral. Aos 56 dias de indução, o quadro de perda óssea instalado tanto em machos quanto em fêmeas, para todos os fragmentos ósseos analisados, é compatível com o quadro de osteoporose.
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3

Manfrin, Thais Mara [UNESP]. "Imunomarcação das proteínas OPG, RANK e RANKL em dentes reimplantados de rato." Universidade Estadual Paulista (UNESP), 2007. http://hdl.handle.net/11449/101206.

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O sistema OPG, RANK e RANKL é uma das mais importantes descobertas da biologia óssea. Essas proteínas regulam as atividades celulares na remodelação do tecido ósseo e na literatura há diversas investigações nos tecidos dentários. No entanto, no reimplante dentário, ainda não foram encontrados relatos. Foi objetivo deste trabalho, avaliar a imunomarcação das proteínas OPG, RANK e RANKL em dentes reimplantados de rato. Um grupo controle foi formado com quatro ratos no qual o reimplante dentário não foi realizado. Vinte e quatro ratos (Rattus norvegicus, albinus) tiveram seu incisivo superior extraído e depois reimplantado formando os seguintes grupos: grupo I – reimplante imediato; grupo II - reimplante tardio sem tratamento e grupo III - reimplante tardio com tratamento endodôntico (ressecção da papila dentária e preenchimento do canal com pasta de hidróxido de cálcio) e tratamento da superfície radicular (raspagem mecânica do ligamento periodontal necrosado e imersão em solução de flúor fosfato acidulado de sódio a 2,5%). Ao final dos períodos experimentais (10 e 60 dias) os ratos foram eutanasiados. Foram obtidos cortes longitudinais parafinados com 6μm de espessura. Os cortes foram submetidos à reação imunoístoquímica mediante a utilização de anticorpos primários para OPG, RANK e RANKL. Os resultados mostraram que a imunomarcação de OPG e RANKL ocorreu em todos os grupos e períodos estudados, muito embora RANKL não tenha sido observada no grupo reimplante imediato aos 60 dias. RANK foi observada somente aos 10 dias de todos os grupos no qual o reimplante foi realizado. A análise qualitativa dos resultados demonstrou que o sistema OPG, RANK e RANKL apresentou marcação evidente no reimplante tardio, sugerindo a efetiva participação no início do processo de reabsorção radicular, uma vez que aos 60 dias a imunomarcação foi discreta.
The OPG, RANK and RANKL system is one of the most important discoveries in bone biology. These proteins are key regulators of bone remodeling and in the literature there are several studies of tooth resorption. However, in tooth replantation, reports have not been found. The purpose of this study was to determine the immunolabeling of OPG, RANK and RANKL in replanted teeth in rats, using immunohistochemistry methodology. A control group (no replanted teeth) was formed by four rats. Twenty-four rats (Rattus norvegicus, albinus) were submitted to the extraction of their upper right incisors. The replantation was performed according to the groups below: group I – immediate replantation; group II – delay replantation without treatment and group III – delay replantation with endodontic treatment (extirpation of papilla and the root canal filled with calcium hydroxide) and root surface treatment (periodontal ligament was removed with scalpel and teeth were immersed in 2% acidulated phosphate sodium fluoride). The animals were euthanized at the end of the experimental periods (10 and 60 days). Longitudinal 6μm slices embedded in paraffin were obtained. The slices were submitted to immunohistochemistry reaction by means of the primary antibodies for OPG, RANK and RANKL proteins. The results showed the expression of OPG in all groups and periods. RANKL expression was observed in all groups, except in the immediate replanted teeth group (60 days). RANK expression was observed only at 10 days in all groups which replantation was performed. The qualitative analysis of our findings indicated that the system OPG, RANK and RANKL presented strong expression in delayed replantation, suggesting effective participation at the beginning of root resorption, since at 60 days the immunostained cells were discreet.
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4

Manfrin, Thais Mara. "Imunomarcação das proteínas OPG, RANK e RANKL em dentes reimplantados de rato /." Araçatuba : [s.n.], 2007. http://hdl.handle.net/11449/101206.

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Resumo: O sistema OPG, RANK e RANKL é uma das mais importantes descobertas da biologia óssea. Essas proteínas regulam as atividades celulares na remodelação do tecido ósseo e na literatura há diversas investigações nos tecidos dentários. No entanto, no reimplante dentário, ainda não foram encontrados relatos. Foi objetivo deste trabalho, avaliar a imunomarcação das proteínas OPG, RANK e RANKL em dentes reimplantados de rato. Um grupo controle foi formado com quatro ratos no qual o reimplante dentário não foi realizado. Vinte e quatro ratos (Rattus norvegicus, albinus) tiveram seu incisivo superior extraído e depois reimplantado formando os seguintes grupos: grupo I - reimplante imediato; grupo II - reimplante tardio sem tratamento e grupo III - reimplante tardio com tratamento endodôntico (ressecção da papila dentária e preenchimento do canal com pasta de hidróxido de cálcio) e tratamento da superfície radicular (raspagem mecânica do ligamento periodontal necrosado e imersão em solução de flúor fosfato acidulado de sódio a 2,5%). Ao final dos períodos experimentais (10 e 60 dias) os ratos foram eutanasiados. Foram obtidos cortes longitudinais parafinados com 6μm de espessura. Os cortes foram submetidos à reação imunoístoquímica mediante a utilização de anticorpos primários para OPG, RANK e RANKL. Os resultados mostraram que a imunomarcação de OPG e RANKL ocorreu em todos os grupos e períodos estudados, muito embora RANKL não tenha sido observada no grupo reimplante imediato aos 60 dias. RANK foi observada somente aos 10 dias de todos os grupos no qual o reimplante foi realizado. A análise qualitativa dos resultados demonstrou que o sistema OPG, RANK e RANKL apresentou marcação evidente no reimplante tardio, sugerindo a efetiva participação no início do processo de reabsorção radicular, uma vez que aos 60 dias a imunomarcação foi discreta.
Abstract: The OPG, RANK and RANKL system is one of the most important discoveries in bone biology. These proteins are key regulators of bone remodeling and in the literature there are several studies of tooth resorption. However, in tooth replantation, reports have not been found. The purpose of this study was to determine the immunolabeling of OPG, RANK and RANKL in replanted teeth in rats, using immunohistochemistry methodology. A control group (no replanted teeth) was formed by four rats. Twenty-four rats (Rattus norvegicus, albinus) were submitted to the extraction of their upper right incisors. The replantation was performed according to the groups below: group I - immediate replantation; group II - delay replantation without treatment and group III - delay replantation with endodontic treatment (extirpation of papilla and the root canal filled with calcium hydroxide) and root surface treatment (periodontal ligament was removed with scalpel and teeth were immersed in 2% acidulated phosphate sodium fluoride). The animals were euthanized at the end of the experimental periods (10 and 60 days). Longitudinal 6μm slices embedded in paraffin were obtained. The slices were submitted to immunohistochemistry reaction by means of the primary antibodies for OPG, RANK and RANKL proteins. The results showed the expression of OPG in all groups and periods. RANKL expression was observed in all groups, except in the immediate replanted teeth group (60 days). RANK expression was observed only at 10 days in all groups which replantation was performed. The qualitative analysis of our findings indicated that the system OPG, RANK and RANKL presented strong expression in delayed replantation, suggesting effective participation at the beginning of root resorption, since at 60 days the immunostained cells were discreet.
Orientador: Wilson Roberto Poi
Coorientador: Roberta Okamoto
Banca: Sônia Regina Panzarini Barioni
Banca: Celso Koogi Sonoda
Banca: Luiz Guilherme Brentegani
Banca: Mirian Marubayashi Hidalgo
Doutor
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5

Amorim, Fernanda Penna Lima Guedes de. "Expressão do receptor ativador de NF-kBETA (Rank), Rank ligante (RANKL), e Osteoproterina (OPG) em sítios de reparo ósseo de ratos diabéticos." reponame:Repositório Institucional da UnB, 2007. http://repositorio.unb.br/handle/10482/1847.

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Dissertação (mestrado)—Universidade de Brasília, Faculdade de Medicina, 2007.
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Os mecanismos envolvidos na modificação do reparo ósseo em diabéticos ainda permanece pouco elucidado. Assim, esse estudo investigou a expressão de reguladores do metabolismo ósseo receptor ativador de NFkB (RANK), RANK ligante (RANKL) e osteoprotegerina (OPG), através da imunohistoquímica e RT-PCR, em sítios de fratura óssea de ratos diabéticos. Foram realizadas fraturas ósseas fechadas em tíbias esquerdas de ratos controle e com diabetes induzido pelo aloxano. A análise histomorfométrica dos sítios de fratura após 7 dias revelaram que os ratos diabéticos (db) apresentaram menor formação óssea e de cartilagem em comparação com o grupo controle. Paralelamente, o número de células RANK e RANKL positivas foi reduzido no grupo diabético. Além disso, células OPG positivas apresentaram-se significantemente diminuídas no grupo diabético comparado ao grupo controle (p=0,05). Entretanto, a razão RANKL/OPG foi similar no grupo controle (0,074) e diabético (0,099) nesse período. Após 14 dias, o número de células RANKL e OPG positivas e a expressão de RNAm desses marcadores foi maior no grupo controle (p=0.008). Apesar de menores níveis, a razão RANKL/OPG no grupo diabético (1,29) foi maior do que no grupo controle (0,90), o que sugere o favorecimento dos mecanismos de reabsorção óssea. Os resultados obtidos demonstram a expressão de marcadores da atividade de formação/remodelação de tecidos duros em sítios de fratura. Modificações no balanço da expressão de RANKL/OPG pode contribuir para o retardo do reparo de fraturas associado ao estado diabético. ____________________________________________________________________________________ ABSTRACT
To clarify the mechanisms of altered bone reapair in diabetic state, we investigate the RANK, RANKL and OPG expression by immunohistochemistry and RT-PCR in the fracture sites of diabetic rats. A closed fracture was performed on the anatomical left tibia in rats either healthy or made diabetic by alloxan. Histomorphometric analysis of fracture site at 7 days after fracture revealed that diabetic rats (db) have significantly lesser bone and cartilage formation at fracture site in comparison with controls. Parallel with this, the number of RANK and RANKL positive cells were slighly decreased in db group. Furthermore, OPG+ cells were significantly lower in db than control (p=0.05). However, the RANKL/OPG ratio was similar in control (0.074) and db (0.099) at this time. At day 14, the numbers of RANKL and OPG positive cells and the mRNA expression for these markers were increased in control group (P=0.008). Despite lower levels, the RANKL/OPG ratio in db group (1.29) was greater than in controls (0.90) what suggets a favoring of pro-resorptive pathways. Our results demonstrate the expression of consistent markers of hard tissue formation/remodeling activities in sites of fractures. The imbalance of RANKL/OPG expression may contribute to the delay of fracture repair during diabetes course.
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Coutinho, Carolina Chiantelli Cláudio [UNESP]. "Expressão das proteínas osteoprotegerina, RANK e RANKL durante o processo de reparo alveolar em ratos: estudo imunoistoquímico." Universidade Estadual Paulista (UNESP), 2005. http://hdl.handle.net/11449/88947.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Na dinâmica da reparação óssea os fenômenos de reabsorção e neoformação são dependentes e acoplados. Proteínas efetivamente envolvidas na diferenciação celular determinam ativação ou inibição das atividades que regulam o ganho ou perda de massa óssea. Dentre as proteínas ósseas identificadas e envolvidas na dinâmica óssea podemos destacar a OPG, a RANK e RANKL como marcadores de atividades celulares. O presente trabalho tem como objetivo identificar, nos diferentes períodos da cronologia do processo de reparo alveolar através de técnica imunoistoquímica, a presença das proteínas OPG, RANK e RANKL. Para tanto foram utilizados 60 ratos machos submetidos à exodontia do incisivo superior direito e perfundidos aos 14, 21 e 28 dias pós-operatórios. As hemi-maxilas contendo o alvéolo dental em reparação foram removidas, pósfixadas, descalcificadas em EDTA, crioprotegidas e obtidos cortes longitudinais com 14æm em criostato. Os cortes foram submetidos à reação imunoistoquímica mediante a utilização de anticorpos primários para OPG, RANK e RANKL, como amplificador foi utilizado o sistema avidina-biotina e a diaminobenzidina (DAB) como cromógeno. Os resultados mostram que qualitativamente ocorre um balanço na expressão das proteínas que caracterizam reabsorção e neoformação óssea nos diferentes períodos estudados, onde aos 14 e 21 dias ocorre maior expressão de RANK. Com relação às proteínas OPG e RANKL, observa-se que elas apresentam-se expressas nas células da linhagem osteoblástica de forma similar, sendo que 28 dias é o período de maior expressão destas proteínas.
In the bone healing dynamics, the resorption and neoformation processes are dependent. Proteins involved in the cellular differentiation determinate the activation or inhibition of the activities that regulate the gain or loss of bone mass. From all of the identified bone proteins, it may be distinguished the OPG, RANK and RANKL. The present study has the aim to identify, in the different periods of alveolar bone healing chronology, the expression of OPG, RANK and RANKL proteins using the immunohistochemistry methodology. To perform this study, 60 male rats had the right upper incisive extracted and they were perfused at 14, 21 and 28 pos-operative days. The hemimaxilla with the rat extraction socket was removed, pos fixed and decalcified in EDTA. Then, they were cryoprotected and longitudinal slices with 14 ìm thickness were obtained in cryostat. The slices were submitted to immunohistochemistry reaction and the primary antibodies used were against OPG, RANK and RANKL proteins. It was used the avidinbiotin system to amplify the sign and diaminobenzidine was the cromogen. The results show that there is a balance in the expression of the proteins, showing that there is an increase in the expression of RANK at 14 and 21 pos-operative periods. In relation to OPG and RANKL, these proteins presents a similar expression in all of the pos-extraction periods analysed in this study and at 28 days after the extraction there is the greater expression of both proteins.
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Coutinho, Carolina Chiantelli Cláudio. "Expressão das proteínas osteoprotegerina, RANK e RANKL durante o processo de reparo alveolar em ratos : estudo imunoistoquímico /." Araçatuba, 2005. http://hdl.handle.net/11449/88947.

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Resumo: Na dinâmica da reparação óssea os fenômenos de reabsorção e neoformação são dependentes e acoplados. Proteínas efetivamente envolvidas na diferenciação celular determinam ativação ou inibição das atividades que regulam o ganho ou perda de massa óssea. Dentre as proteínas ósseas identificadas e envolvidas na dinâmica óssea podemos destacar a OPG, a RANK e RANKL como marcadores de atividades celulares. O presente trabalho tem como objetivo identificar, nos diferentes períodos da cronologia do processo de reparo alveolar através de técnica imunoistoquímica, a presença das proteínas OPG, RANK e RANKL. Para tanto foram utilizados 60 ratos machos submetidos à exodontia do incisivo superior direito e perfundidos aos 14, 21 e 28 dias pós-operatórios. As hemi-maxilas contendo o alvéolo dental em reparação foram removidas, pósfixadas, descalcificadas em EDTA, crioprotegidas e obtidos cortes longitudinais com 14æm em criostato. Os cortes foram submetidos à reação imunoistoquímica mediante a utilização de anticorpos primários para OPG, RANK e RANKL, como amplificador foi utilizado o sistema avidina-biotina e a diaminobenzidina (DAB) como cromógeno. Os resultados mostram que qualitativamente ocorre um balanço na expressão das proteínas que caracterizam reabsorção e neoformação óssea nos diferentes períodos estudados, onde aos 14 e 21 dias ocorre maior expressão de RANK. Com relação às proteínas OPG e RANKL, observa-se que elas apresentam-se expressas nas células da linhagem osteoblástica de forma similar, sendo que 28 dias é o período de maior expressão destas proteínas.
Abstract: In the bone healing dynamics, the resorption and neoformation processes are dependent. Proteins involved in the cellular differentiation determinate the activation or inhibition of the activities that regulate the gain or loss of bone mass. From all of the identified bone proteins, it may be distinguished the OPG, RANK and RANKL. The present study has the aim to identify, in the different periods of alveolar bone healing chronology, the expression of OPG, RANK and RANKL proteins using the immunohistochemistry methodology. To perform this study, 60 male rats had the right upper incisive extracted and they were perfused at 14, 21 and 28 pos-operative days. The hemimaxilla with the rat extraction socket was removed, pos fixed and decalcified in EDTA. Then, they were cryoprotected and longitudinal slices with 14 ìm thickness were obtained in cryostat. The slices were submitted to immunohistochemistry reaction and the primary antibodies used were against OPG, RANK and RANKL proteins. It was used the avidinbiotin system to amplify the sign and diaminobenzidine was the cromogen. The results show that there is a balance in the expression of the proteins, showing that there is an increase in the expression of RANK at 14 and 21 pos-operative periods. In relation to OPG and RANKL, these proteins presents a similar expression in all of the pos-extraction periods analysed in this study and at 28 days after the extraction there is the greater expression of both proteins.
Orientador: Roberta Okamoto
Coorientador: Roelf Justino Cruz Rizollo
Banca: Idelmo Rangel Garcia Júnior
Banca: Victor Elias Arana-Chavez
Mestre
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8

Maia, Concei??o Aparecida Dornelas Monteiro. "An?lise imuno-histoqu?mica das prote?nas RANK, RANKL e OPG em dentes de ratos reimplantados." Universidade Federal do Rio Grande do Norte, 2014. http://repositorio.ufrn.br/handle/123456789/19980.

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Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico - CNPq
Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES
O sistema RANK/RANKL/OPG contribui para a compreens?o do processo e regula??o da forma??o e reabsor??o do osso, tendo sido o maior avan?o na biologia ?ssea com rela??o a osteoclastog?nese. RANKL e OPG inibem RANK regulando a forma??o, ativa??o e sobreviv?ncia de osteoclastos na remodela??o ?ssea. O objetivo desse estudo foi investigar a express?o dos marcadores RANKL/RANK/OPG em dentes de ratos reimplantados, bem como observar a rela??o entre a express?o desses marcadores com o processo de reabsor??o dent?ria e ?ssea. Foram utilizados 30 incisivos superiores direitos de 30 ratos machos, adultos, da linhagem Wistar (Rattus norvegicus albinus). Os dentes foram avulsionados e divididos em dois grupos que permaneceram extra-alveolar em ar seco: G1 (n=15) - 5 minutos e G2 (n=15) - 60 minutos, e em seguida foram reimplantados e analisados nos intervalos de 1, 3 e 7 dias. Finalizado os per?odos experimentais, ocorreu a eutan?sia dos animais. Cortes longitudinais com 5?m de espessura foram obtidos e corados pela t?cnica H/E para a an?lise histol?gica e cortes com 3?m de espessura foram submetidos ? rea??o imuno-histoqu?mica mediante a utiliza??o de anticorpos prim?rios para ratos como OPG, RANK e RANKL. Os resultados demonstraram que o sistema RANK/RANKL/OPG participa ativamente, tanto do processo de reparo de dentes de ratos reimplantados, quanto das reabsor??es dent?rias e ?sseas; que RANKL apresentou maior imunomarca??o em ambos os grupos, participando em todas as fases da reabsor??o ?ssea e dent?ria; e o aumento da express?o de RANKL foi observada em ambos os grupos em todos os intervalos de tempo, comprovando que a resposta inflamat?ria no ligamento periodontal ocorre no in?cio do processo de reparo; e que a fraca express?o de RANK e OPG e o aumento da express?o de RANKL sugere uma diminui??o da reabsor??o ativa e aumento da reabsor??o reparada no osso e no cemento, sendo maior no osso.
The RANK / RANKL / OPG sy stem plays an important role in bone formation and resorption . This finding has been regarded as one of the m ost important advances in the understanding of bone biology with respect to osteoclastogenesis. The aim of this study was to investigate the expression of RANKL / RANK / OPG markers in reimplanted t eeth of rats, and to observe the relationship between the expression of these markers and to oth and bone resorption. Thirty male Wistar rats (Rattus norvegicus albinos) had their maxillary right incisors extrac ted , and were divided into 2 groups according to the period that the extracted teeth were kept in dry air before reimplantation : G1 (n = 15) - 5 minutes , and G2 (n = 15) - 60 minutes . After reimplantation, teeth were analyzed at intervals of 1, 3 and 7 da ys. After these experimental periods, the animals were euthanized. Longitudinal sections with 5?m thick were obtained and stained with Hematoxylin and Eosin for histological analysis , while 3?m thick sections were subjected to immunohistochemical analysis of OPG , RANK and RANKL. The results showed that the RANK / RANKL / OPG system actively participates in both the repair process, as well as tooth and bone resorption . Extr a - alveolar time of 60 minutes before replantation caused minor expressions of RANKL a nd OPG, not influencing the expression of RANK; RANKL immunostaining showed higher in both groups when compared to other biomarkers, participating in all phases of bone and tooth resorption; RANKL was associated to both osteoclastogenesis and c ell ular proliferation , and was expressed in both groups.
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9

Mycio-Mommers, Luba. "An investigation of the robustness of the Type I error rate of the t, M-W-W, Welch and Welch on ranks tests applied to reaction time populations with unequal variances." Thesis, University of Ottawa (Canada), 1995. http://hdl.handle.net/10393/10419.

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This thesis investigates the robustness of the Type I error rate of the t test, the t test on ranks (Mann-Whitney-Wilcoxon), the Welch test and the Welch test on ranks applied to reaction time populations with unequal variances. Reaction time is often encountered as a dependent variable in educational and behavioural research. Reaction time data are typically skewed and are commonly modelled on a family of distributions known as the ex-Gaussian. A Monte Carlo study compared the robustness of type I error rates of the four tests under study under 36 conditions wherein four factors were observed: total sample size ($N=24$ and 72), ratio of sample sizes ($n\sb1:n\sb2$ = 1:1, 1:2, and 1:3); ratio of population variances (var1:var2 = 1:1, 1:2, 1:4, and 1:9), and negative and positive conditions. In each condition, 5,000 scores were generated from Miller's (1988) most skewed distribution that represented a boundary condition of reaction time data. The results indicated that the t test was the preferred option under all simulated conditions, except the negative condition. Furthermore, under the negative condition, all four tests produced liberal Type I errors.
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10

Barkov, Ilia. "Diagonal Ranks of Semigroups." Thesis, Linnéuniversitetet, Institutionen för matematik (MA), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-31383.

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We introduce the notion of diagonal ranks of semigroups,which are numerical characteristics of semigroups. Some base propertiesof diagonal ranks are obtained. A new criterion for a monoidbeing a group is obtained using diagonal ranks.For some semigroup classes we investigate whether their diagonal acts are finitely generatedor not. For the semigroups of full transformations, partial transformations andbinary relations we find the general form of the generating pairs.
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11

Summerhayes, Catherine, and catherine summerhayes@anu edu au. "Film as Cultural Performance." The Australian National University. School of Art, 2002. http://thesis.anu.edu.au./public/adt-ANU20090210.095136.

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This thesis investigates how Victor Turner’s concept of ‘cultural performance’ can be used to explore and analyse the experience of film. Drawing on performance theory, hermeneutics, phenomenology and Bakhtin’s dialogism, Sections One and Two develop this investigation through a theoretic discussion which relates and yet distinguishes between three levels of ‘performance’ in film: filmmaking performance, performances as text and cultural performances. The theory is grounded within four films which were researched for this thesis: Once Were Warriors (Lee Tamahori, 1994), Rats in the Ranks (Bob Connolly and Robin Anderson,1996), beDevil (Tracey Moffatt, 1993) and Link-Up Diary (David MacDougall, 1987). Section Three undertakes the close analyses of the latter two films. These analyses address specific cultural performances that are performed ‘across’ cultures and which are concerned particularly with Australian society’s relationship with indigenous Australians. ¶ Section One locates Turner’s concept of ‘cultural performance’ within his wider theory of ‘social drama’ and introduces the three-tiered mode of analysis which is developed throughout this thesis. His concept of ‘liminality’ is also investigated in order to consider specific relationships between performances which take place in film and theatre. Performances which take place in film are located in this Section within the theatrical understanding of performance as ‘for an audience’. I describe this relationship between performances in film and theatre through Kristeva’s interpretation of Bakhtin’s concept of heteroglossia as intertextuality, especially through her distinction of a ‘transformative’ intertextuality. Three specific concepts from theatre and performance theory are interrogated for their relevance to film theory: 1. Brecht’s theory of ‘gest’, 2. ‘direct address to the audience’ in relation to the ‘gaze’ in film and 3. Rebecca Schneider’s conceptualisation of ‘the performance artist’. ¶ Using these three tropes of performance, Section Two develops a theory of performance in film. Besides Turner’s concept of ‘cultural performance’, this theory draws on aspects of several other substantial bodies of work. These works include Richard Schechner’s performance theory, Michael Taussig’s understanding of ‘mimesis’, Vivian Sobchack’s phenomenology of film, Paul Ricoeur’s theory of text ‘as meaningful action’, Gadamer’s concept of ‘meaningful play’, Bakhtin’s conceptualisation of a ‘dialogic’ text and Catherine Bell’s theory of ‘ritualised behaviour’. The two analyses in Section Three do not rigidly follow the three-tiered process of analysis which is developed in the previous two Sections. They rather focus on the films as sites for particular cultural performances which are specific for each film and which need for their description, different aspects of the theory that is offered through this thesis. These analyses especially draw on my interpretation of David MacDougall’s ‘transcultural cinema’ and Jodi Brook’s conceptualisation of a ‘gestural practice’ in film, which she positions both in terms of Brecht’s theatrical concept of ‘gest’ and Walter Benjamin’s concept of the ‘shock’ of modernity. ¶ The film analyses are of one fiction film, beDevil, and one non-fiction film, Link-Up Diary. Both films use audiovisual images of Aboriginal Australians as content. According the terms of this thesis, these people must also be considered as filmmakers. Although this role may constitute varying degrees of authority and power, a film analysis which considers the filmmaking roles of people whose images are present in the filmic text also allows a particular consideration of the social relationships which exist between people who ‘film’ and people who ‘are filmed’. My focus on the cultural performances of these two films allowed an even closer description of this relationship for two reasons. Firstly, both Moffatt and MacDougall respectively present their own images in the films. Secondly, my analyses of these films as cultural performance draw out and describe the different ways in which the two films address the same ‘social drama’: the relationship between indigenous and non-indigenous Australians. My analyses expose how a description of these differences in address can extend beyond the distinction between one film as ‘fiction’ and the other as ‘non-fiction’ towards a description of the different ways in which people relate to each other, at both the individual level and at the level of society, through the production and reception of a particular film. While locating these films as cultural performances within in particular sets of social relationships, my consideration of film in this thesis in terms of theatrical performance also enables a description of the experience of film which draws on the social experience of live theatre. The theory developed in this thesis and its application in the analyses of these two films suggest further areas of research which might look more closely at whether or not, or how much people draw from the social practices of live theatre as they live their lives with film – a signifying practice which has existed just over one hundred years.
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12

Mankada, Covilakom Mithun Varma. "RANS AND HYBRID RANS/LES COMPUTATIONS FOR THREE-DIMENSIONAL WINGS WITH ICE ACCRETION." MSSTATE, 2006. http://sun.library.msstate.edu/ETD-db/theses/available/etd-11092006-232711/.

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Computational investigations were carried out to evaluate the effectiveness and usability of hybrid RANS/LES techniques for predicting the unsteady separated flow over wings with ice accretion. RANS and hybrid RANS/LES computations were performed using the viscous flow solver CHEM with the SST turbulence model. Two configurations were considered during the study: an extruded wing with a glaze-ice shape and a swept wing with a simulated glaze-ice accretion. Hybrid RANS/LES results, in general, predict a less active shear layer ``roll up' than seen in the experimental data. Qualitative improvements are seen in the hybrid RANS/LES results over corresponding RANS results. The extruded wing results show that the CHEM hybrid RANS/LES results are similar to the AVUS DES results. The use of preconditioning and a different turbulent model in CHEM showed a slight improvement in results.
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13

Lima, Mariana dos Reis. "Efeito da calendula officinalis em ratos submetidos a periodontite experimental: participação das vias RANK-RANKL-OPG e WNT B-CATENINA." reponame:Repositório Institucional da UFC, 2016. http://www.repositorio.ufc.br/handle/riufc/21662.

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LIMA, M. R. Efeito da calendula officinalis em ratos submetidos a periodontite experimental: participação das vias RANK-RANKL-OPG e WNT B-CATENINA. 2016. 66 f. Dissertação (Mestrado em Ciências Morfofuncionais) - Faculdade de Medicina, Universidade Federal do Ceará, Fortaleza, 2016.
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Periodontitis is an infecto-inflammatory disease that leads to connective tissue and alveolar bone loss. Calendula officinalis (CLO) has been used due to its anti-inflammatory effects. Therefore the aim of this study was to evaluate the effect of CLO on alveolar bone loss (ABL) in rats focusing on RANK-RANKL-OPG and WNT signaling pathways. Experimental periodontitis (EP) was induced through placement of a nylon ligature around the upper left 2nd molar, and the hemimaxilla used as control. The animals were divided in groups: Normal, subjected to no treatment; Saline (SAL), that received 2 ml/kg of 0,9% saline solution orally; or CLO at 90 mg/kg orally, 30 minutes before EP and daily for 11 days until euthanasia. In order to evaluate the periodontal tissue, it macroscopic, micro-tomographic, electron scanning microscopy (SEM), confocal microscopy and polarized light microscopy analyses were performed, as well as immunohistochemistry for WNT 10b, β-catenin, DKK-1, RANK, RANKL, and OPG. During euthanasia the gingival tissue was removed for malonaldehyde (MDA) assay. Treatment with CLO significantly prevented ABL, preserved bone internal microstructure (p<0.05) and topography, and also preserved collagen fibers from the periodontal ligament, when compared to SAL. CLO significantly increased the number of immunopositive cells for WNT 10b, β-catenin and OPG and reduced DKK-1, RANK (p>0.05) and RANKL. CLO reduced the gingival levels of MDA compared to SAL (p<0.05). In this way, we can conclude that CLO prevented ABL via RANK-RANKL-OPG and WNT signaling pathway.
A periodontite é uma doença infecto-inflamatória que causa perda de tecido conjuntivo e osso alveolar. A Calendula officinalis (CLO) tem sido utilizada pelos seus efeitos anti-inflamatórios. Nesse contexto, o objetivo deste trabalho foi avaliar efeito da CLO na perda óssea alveolar (POA) em ratos com foco na participação do eixo RANK-RANKL-OPG e da via WNT/β-catenina. A periodontite experimental (PE) foi induzida através da inserção do fio (nailon 3.0) em torno do 2º molar superior esquerdo, e hemiarcada contralateral usada como controle. Os animais foram divididos em grupos: Normal, não submetido a nenhum procedimento; Salina (SAL), que receberam 2 ml/kg de solução salina 0,9% - v.o.; ou CLO na dose de 90 mg/kg - v.o. 30 min antes da PE e diariamente durante por 11 dias até eutanásia. Para avaliação do tecido periodontal realizaram-se análises macroscópica, por microtomografia computadorizada, por microscopia eletrônica de varredura (MEV), microscopia confocal e microscopia por luz polarizada, imunohistoquímica para WNT 10b, β-catenina, DKK-1, RANK, RANKL e OPG. Por ocasião da eutanásia foi removido tecido gengival para avaliação dos níveis de malondialdeído (MDA). O tratamento com CLO preveniu de forma significante a POA, preservou a microestrutura interna (p<0,05) e topografia do tecido ósseo, e preservou também as fibras colágenas do ligamento periodontal, quando comparado a SAL. A CLO provocou aumento significante de células imunopositivas para WNT 10b, β-catenina e OPG e redução na imunomarcação de DKK-1, RANK (p>0,05) e RANKL. CLO reduziu os níveis de MDA gengivais comparados a SAL (p<0,05). Desta forma, podemos concluir que a CLO previne a POA com participação do eixo RANK-RANKL-OPG e da via WNT/β-catenina.
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14

Acar, B. Serpil. "Statistical data analysis by using ranks." Thesis, Loughborough University, 1985. https://dspace.lboro.ac.uk/2134/32010.

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15

Fiallos, Ana Cristina de Mello. "Estudo do ranelato de estrÃncio no reparo Ãsseo de defeitos crÃticos em calvÃria de ratos: participaÃÃo da via RANK/RANKL/OPG." Universidade Federal do CearÃ, 2013. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=9577.

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O reparo Ãsseo à um processo multifuncional com a participaÃÃo de vÃrios mediadores. Dentre os fÃrmacos que interferem nesse processo, destaca-se o Ranelato de EstrÃncio (RSr), o qual apresenta um mecanismo de aÃÃo dual, estimulando a neoformaÃÃo ao mesmo tempo que inibe a reabsorÃÃo Ãssea. Para avaliar a capacidade osteoindutiva, modelos que favorecem o estudo do potencial de reparo Ãsseo local tÃm sido utilizados, tais como o de induÃÃo de defeitos de tamanhos crÃticos (CSD) em calvÃrias de ratos. O objetivo deste estudo foi avaliar o RSr no reparo Ãsseo de defeitos crÃticos de 8 mm de diÃmetro induzidos em calvÃria de ratos. Para tanto, imediatamente apÃs a cirurgia, os CSD receberam uma Ãnica aplicaÃÃo de RSr (2,1 e 6,3 mg) ou nenhum tratamento (Controle). Grupos de animais foram sacrificados a 0 h e aos 15, 45, 90 e 120 dias apÃs a induÃÃo do CSD e calvÃrias foram processadas para anÃlise macroscÃpica, por meio de Tomografia Computadorizada tipo Cone Beam (TCCB), histolÃgica (HE) e imunohistoquÃmica para RANKL e OPG. Na anÃlise por TCCB, verificou-se que, no grupo RSr 6,3 mg, o RSr causou reduÃÃo significativa da Ãrea do CSD aos 90 dias (67,79  2,32 mmÂ) e 120 dias (62,28  4,17 mmÂ), quando comparadas Ãs calvÃrias recÃm-induzidas (0 h) (78,61  0,96 mmÂ) (p<0,05), mas nÃo em relaÃÃo ao grupo Controle apÃs 90 dias (74,2  2,73 mmÂ) e 120 dias (72,04  1,74 mmÂ) (p>0,05). Na anÃlise histolÃgica das calvÃrias dos animais do grupo Controle foram observadas alteraÃÃes histolÃgicas significantes relacionadas ao reparo Ãsseo como neoformaÃÃo Ãssea restrita Ãs bordas do CSD quando comparados aos animais do grupo normal em todos os perÃodos experimentais (p<0,05). Os animais do grupo RSr (2,1 mg) nÃo apresentaram alteraÃÃes histolÃgicas significantes quando comparados ao grupo Controle em todos os perÃodos experimentais (p>0,05) enquanto que, nos animais do grupo RSr (6,3 mg), foram observados aspectos histolÃgicos compatÃveis com reparo Ãsseo aos 90 dias e aos 120 dias como neoformaÃÃo Ãssea em borda e no centro do CSD com diferenÃas significativas quando comparados aos grupos Controle ou RSr 2,1 mg (p<0,05). Complementando esses resultados, as calvÃrias dos animais apÃs 120 dias da aplicaÃÃo local de RSr (6,3 mg) apresentaram intensa imunoexpressÃo para OPG e negativa para RANKL, enquanto que as calvÃrias do grupo Controle apresentaram imunoexpressÃo moderada apenas para RANKL. Assim, pode-se concluir que o tratamento local com RSr evidenciou seu papel osteoindutor favorecendo a reparaÃÃo Ãssea do CSD pela modulaÃÃo da via RANKL/RANK/OPG.
The bone repair is a multifunctional process involving various mediators. Among the many drugs that interfere with this process, we highlight the Strontium Ranelate (SrR), which has a dual mechanism of action, stimulating neoformation at the same time, which inhibits bone resorption. To evaluate the osteoinductive capacity, models of study that investigate the potential for bone repair site have been used, such as induction of critical size defects (CSD) in rat calvaria. The aim of this study was to evaluate bone healing induced by SrR in critical defects of 8 mm in diameter in rat calvaria. For this purpose, immediately after surgery, the CSD received a single application of SrR (2.1 and 6.3 mg) or no treatment (Control). Groups of animals were sacrificed at 0 h and at 15, 45, 90 and 120 days after induction of CSD and calvarial samples were removed and processed for analysis by macroscopic type Cone Beam Computed Tomography (CBCT), histological (HE) and immunohistochemical for RANKL and OPG. In CBCT analysis, it was found that induction of CSD group SrR 6.3 mg caused a significant reduction of the areas of CSD at 90 days (67.79  2.32 mmÂ) and at 120 days (62.28  4.17 mmÂ) compared to calvariae newly induced (0 h) (78.61 mm  0.96) (p<0.05) but not compared to Control groups at 90 days (74.2  2.73 mmÂ) and at 120 days (72.04 Â1.74 mmÂ) (p>0.05). We observed in the histological analysis of calvariae of Control groups significant changes related to bone repair when compared to normal group (p<0.05). The animals that received SrR (2.1 mg) showed no significant histological changes, compared to the Control groups in all experimental periods (p>0.05), while animals of SrR 6.3 mg group showed significantly histological features consistent with bone repair at 90 days and at 120 days as neoformation in edge and center of the CSD when compared to Control or SrR 2.1 mg groups (p<0.05). To complement these results, the calvariae of animals after 120 days of topical application of SrR (6.3 mg) showed intense immunostaining for OPG and RANKL negative, whereas the calvariae of Control groups showed moderate immunoreactivity only for RANKL. Thus, it can be concluded that the local treatment with SrR (6.3 mg) revealed its role favoring osteoinductive bone repair by modulating the CSD RANK/RANKL/OPG.
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16

Fiallos, Ana Cristina de Mello. "Estudo do ranelato de estrôncio no reparo ósseo de defeitos críticos em calvária de ratos : participação da via RANK/RANKL/OPG." reponame:Repositório Institucional da UFC, 2013. http://www.repositorio.ufc.br/handle/riufc/6873.

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FIALLOS, Ana Cristina de Mello. Estudo do ranelato de estrôncio no reparo ósseo de defeitos críticos em calvária de ratos : participação da via RANK/RANKL/OPG. 2013. 106 f. Tese (Doutorado em Odontologia) - Universidade Federal do Ceará. Faculdade de Farmácia, Odontologia e Enfermagem, Fortaleza, 2013.
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The bone repair is a multifunctional process involving various mediators. Among the many drugs that interfere with this process, we highlight the Strontium Ranelate (SrR), which has a dual mechanism of action, stimulating neoformation at the same time, which inhibits bone resorption. To evaluate the osteoinductive capacity, models of study that investigate the potential for bone repair site have been used, such as induction of critical size defects (CSD) in rat calvaria. The aim of this study was to evaluate bone healing induced by SrR in critical defects of 8 mm in diameter in rat calvaria. For this purpose, immediately after surgery, the CSD received a single application of SrR (2.1 and 6.3 mg) or no treatment (Control). Groups of animals were sacrificed at 0 h and at 15, 45, 90 and 120 days after induction of CSD and calvarial samples were removed and processed for analysis by macroscopic type Cone Beam Computed Tomography (CBCT), histological (HE) and immunohistochemical for RANKL and OPG. In CBCT analysis, it was found that induction of CSD group SrR 6.3 mg caused a significant reduction of the areas of CSD at 90 days (67.79 ± 2.32 mm²) and at 120 days (62.28 ± 4.17 mm²) compared to calvariae newly induced (0 h) (78.61 mm² ± 0.96) (p<0.05) but not compared to Control groups at 90 days (74.2 ± 2.73 mm²) and at 120 days (72.04 ±1.74 mm²) (p>0.05). We observed in the histological analysis of calvariae of Control groups significant changes related to bone repair when compared to normal group (p<0.05). The animals that received SrR (2.1 mg) showed no significant histological changes, compared to the Control groups in all experimental periods (p>0.05), while animals of SrR 6.3 mg group showed significantly histological features consistent with bone repair at 90 days and at 120 days as neoformation in edge and center of the CSD when compared to Control or SrR 2.1 mg groups (p<0.05). To complement these results, the calvariae of animals after 120 days of topical application of SrR (6.3 mg) showed intense immunostaining for OPG and RANKL negative, whereas the calvariae of Control groups showed moderate immunoreactivity only for RANKL. Thus, it can be concluded that the local treatment with SrR (6.3 mg) revealed its role favoring osteoinductive bone repair by modulating the CSD RANK/RANKL/OPG.
O reparo ósseo é um processo multifuncional com a participação de vários mediadores. Dentre os fármacos que interferem nesse processo, destaca-se o Ranelato de Estrôncio (RSr), o qual apresenta um mecanismo de ação dual, estimulando a neoformação ao mesmo tempo que inibe a reabsorção óssea. Para avaliar a capacidade osteoindutiva, modelos que favorecem o estudo do potencial de reparo ósseo local têm sido utilizados, tais como o de indução de defeitos de tamanhos críticos (CSD) em calvárias de ratos. O objetivo deste estudo foi avaliar o RSr no reparo ósseo de defeitos críticos de 8 mm de diâmetro induzidos em calvária de ratos. Para tanto, imediatamente após a cirurgia, os CSD receberam uma única aplicação de RSr (2,1 e 6,3 mg) ou nenhum tratamento (Controle). Grupos de animais foram sacrificados a 0 h e aos 15, 45, 90 e 120 dias após a indução do CSD e calvárias foram processadas para análise macroscópica, por meio de Tomografia Computadorizada tipo Cone Beam (TCCB), histológica (HE) e imunohistoquímica para RANKL e OPG. Na análise por TCCB, verificou-se que, no grupo RSr 6,3 mg, o RSr causou redução significativa da área do CSD aos 90 dias (67,79 ± 2,32 mm²) e 120 dias (62,28 ± 4,17 mm²), quando comparadas às calvárias recém-induzidas (0 h) (78,61 ± 0,96 mm²) (p<0,05), mas não em relação ao grupo Controle após 90 dias (74,2 ± 2,73 mm²) e 120 dias (72,04 ± 1,74 mm²) (p>0,05). Na análise histológica das calvárias dos animais do grupo Controle foram observadas alterações histológicas significantes relacionadas ao reparo ósseo como neoformação óssea restrita às bordas do CSD quando comparados aos animais do grupo normal em todos os períodos experimentais (p<0,05). Os animais do grupo RSr (2,1 mg) não apresentaram alterações histológicas significantes quando comparados ao grupo Controle em todos os períodos experimentais (p>0,05) enquanto que, nos animais do grupo RSr (6,3 mg), foram observados aspectos histológicos compatíveis com reparo ósseo aos 90 dias e aos 120 dias como neoformação óssea em borda e no centro do CSD com diferenças significativas quando comparados aos grupos Controle ou RSr 2,1 mg (p<0,05). Complementando esses resultados, as calvárias dos animais após 120 dias da aplicação local de RSr (6,3 mg) apresentaram intensa imunoexpressão para OPG e negativa para RANKL, enquanto que as calvárias do grupo Controle apresentaram imunoexpressão moderada apenas para RANKL. Assim, pode-se concluir que o tratamento local com RSr evidenciou seu papel osteoindutor favorecendo a reparação óssea do CSD pela modulação da via RANKL/RANK/OPG.
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17

Kudo, Jun S. M. Massachusetts Institute of Technology. "Robust adaptive high-order RANS methods." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/95563.

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Thesis: S.M., Massachusetts Institute of Technology, Computation for Design and Optimization Program, 2014.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 89-94).
The ability to achieve accurate predictions of turbulent flow over arbitrarily complex geometries proves critical in the advancement of aerospace design. However, quantitatively accurate results from modern Computational Fluid Dynamics (CFD) tools are often accompanied by intractably high computational expenses and are significantly hindered by the lack of automation. In particular, the generation of a suitable mesh for a given flow problem often requires significant amounts of human input. This process however encounters difficulties for turbulent flows which exhibit a wide range of length scales that must be spatially resolved for an accurate solution. Higher-order adaptive methods are attractive candidates for addressing these deficiencies by promising accurate solutions at a reduced cost in a highly automated fashion. However, these methods in general are still not robust enough for industrial applications and significant advances must be made before the true realization of robust automated three-dimensional turbulent CFD. This thesis presents steps towards this realization of a robust high-order adaptive Reynolds-Averaged Navier-Stokes (RANS) method for the analysis of turbulent flows. Specifically, a discontinuous Galerkin (DG) discretization of the RANS equations and an output-based error estimation with an associated mesh adaptation algorithm is demonstrated. To improve the robustness associated with the RANS discretization, modifications to the negative continuation of the Spalart-Allmaras turbulence model are reviewed and numerically demonstrated on a test case. An existing metric-based adaptation framework is adopted and modified to improve the procedure's global convergence behavior. The resulting discretization and modified adaptation procedure is then applied to two-dimensional and three-dimensional turbulent flows to demonstrate the overall capability of the method.
by Jun Kudo.
S.M.
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18

Clark, David Alan. "L-series and ranks of elliptic curves." Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61910.

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19

Sitanggang, Khairil Irfan. "Boussinesq-equation and rans hybrid wave model." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-2795.

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20

Aubagnac-Karkar, Damien. "Sectional soot modeling for Diesel RANS simulations." Thesis, Châtenay-Malabry, Ecole centrale de Paris, 2014. http://www.theses.fr/2014ECAP0061/document.

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Les particules de suies issues de moteur Diesel constituent un enjeu de santé publique et sont soumises à des réglementations de plus en plus strictes. Les constructeurs automobiles ont donc besoin de modèles capables de prédire l’évolution en nombre et en taille de ces particules de suies. Dans ce cadre, un modèle de suies basé sur une représentation sectionnelle de la phase solide est proposé dans cette thèse. Le choix de ce type d’approche est d’abord justifié par l’étude de l’état de l’art de la modélisation des suies. Le modèle de suies proposé est ensuite décrit. A chaque instant et en chaque point du maillage, les particules de suies sont réparties en sections selon leur taille et l’évolution de chaque section est gouvernée par : • une équation de transport;• des termes sources modélisant l’interaction avec la phase gazeuse (nucléation, condensation, croissance de surface et oxydation des suies);• des termes sources collisionnels permettant de représenter les interactions entre suies (condensation et coagulation). Ce modèle de suies nécessite donc la connaissance des concentrations locales et instantanées des précurseurs de suies et des espèces consommées par les schémas de réactions de surface des suies. Les schémas fournissant ces informations pour des conditions thermodynamiques rencontrées dans des moteurs Diesel comportant des centaines d’espèces et des milliers de réactions, ils ne peuvent être utilisés directement dans des calculs de CFD. Pour pallier cela, l’approche de tabulation de la chimie VPTHC (Variable Pressure Tabulated Homogeneous Chemistry) a été proposée. Cette approche est basée sur l’approche ADF (Approximated Diffusion Flame) qui a été simplifiée pour permettre son emploi couplé au modèle de suies sectionnel. Dans un premier temps, la capacité du modèle tabulé à reproduire la cinétique chimique a été validée par comparaison des résultats obtenus avec ceux de réacteurs homogènes avec loi de piston équivalents. Finalement, le modèle VPTHC, couplé au modèle de suies sectionnel, a été validé sur une base d’essais moteur dédiée avec des mesures de distribution en taille de suies à l’échappement. Cette base comporte des variations de durée d’injection, de pression d’injection et de taux d’EGR à la fois pour un carburant Diesel commercial et pour le carburant modèle utilisé dans les calculs. Les prédictions des débits horaires de suies et des distributions à l’échappement obtenues sont en bon accord avec les mesures.Ensuite, les résultats du modèle ont été comparés avec les mesures plus académiques et détaillées du Spray A de l’Engine Combustion Network, un spray à haute pression et température. Cette seconde validation expérimentale a permis l’étude du comportement du modèle dans des régimes transitoires
Soot particles emitted by Diesel engines cause major public health issues. Car manufacturers need models able to predict soot number and size distribution to face the more and more stringent norms.In this context, a soot model based on a sectional description of the solid phase is proposed in this work. First, the type of approach is discussed on the base of state of the art of the current soot models. Then, the proposed model is described. At every location and time-step of the simulation, soot particles are split into sections depending on their size. Each section evolution is governed by: • a transport equation;• source terms representing its interaction with the gaseous phase (particle inception, condensation surface growth and oxidation);• source terms representing its interaction with other sections (condensation and coagulation).This soot model requires the knowledge of local and instantaneous concentrations of minor species involved in soot formation and evolution. The kinetic schemes including these species are composed of hundreds of species and thousands of reactions. It is not possible to use them in 3D-CFD simulations. Therefore, the tabulated approach VPTHC (Variable Pressure Tabulated Homogeneous Chemistry) has been proposed. This approach is based on the ADF approach (Approximated Diffusion Flame) which has been simplified in order to be coupled with the sectional soot model. First, this tabulated combustion model ability to reproduce detailed kinetic scheme prediction has been validated on variable pressure and mixture fraction homogeneous reactors designed for this purpose. Then, the models predictions have been compared to experimental measurement of soot yields and particle size distributions of Diesel engines. The validation database includes variations of injection duration, injection pressure and EGR rate performed with a commercial Diesel fuel as well as the surrogate used in simulations. The model predictions agree with the experiments for most cases. Finally, the model predictions have been compared on a more detailed and academical case with the Engine Combustion Network Spray A, a high pressure Diesel spray. This final experimental validation provides data to evaluate the model predictions in transient conditions
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21

Eastwood, S. J. "Hybrid LES – RANS of complex geometry jets." Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.598741.

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A promising technique for exploring jet flows is large eddy simulation (LES). However for jet LES a number of key unanswered questions remain. These include the sensitivity of solutions to the numerical scheme, subgrid scale (SGS) model and inlet conditions. Results show that for more dissipative, robust solvers often found in industry, SGS model omission can give useful results. Solutions which use no SGS model are called Numerical LES (NLES). For less dissipative codes, solutions are found to be relatively insensitive to the choice of SGS model. An industrial based solver is selected and validated further by making acoustic and hot jet predictions using the NLES approach. Encouraging agreement with measurements is shown. To relieve computational cost, the near wall modelling issue is also addressed. A novel method is used to blend a near wall Reynolds averaged Navier Stokes (RANS) method with NLES used away from the wall. Blending between the two regions makes use of the Hamilton Jacobi equation. Real engines have high bypass ratio nozzles and so the flow through these is explored. Predictions are made using the hybrid RANS-NLES strategy. Different case set ups are simulated including hot and cold jets and a range of meshes from 6 x 106 to 50 x 106 cells. For all the meshes, results show encouraging agreement with measurements. The near wall RANS modelling is helpful in preventing non-physical separation from curved surfaces highlighting the usefulness of the hybrid approach. A pylon, which attaches the engine to the wing, is shown to influence the flow development, having a significant impact on peak turbulence levels and spreading rates. Wakes, simulating those shed by upstream turbomachinery, are included in the nozzle geometry. The wakes are introduced using a body force model which prevents the need to explicitly model blade geometry. The results have demonstrated that real geometry effects are particularly influential and should be taken into account when moving towards real engine simulations.
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Doo, Christopher R. "A RANS investigation of hull-propeller interaction." Thesis, University of Strathclyde, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401435.

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23

Lederer, Julien Pascal. "Soutenabilité, risques climatiques et analyse d'équations RANS." Rennes 1, 2006. http://www.theses.fr/2006REN1S008.

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On définit des modèles et problèmes mathématiques concernant la notion de politique soutenable/durable dans un point de vue axé sur les risques climatiques. Le résultat est un problème de contrôle optimal intégrant un système simpliste couplant économie, finance et équations de Navier-Stokes moyennées (RANS). L'analyse du système RANS est traitée dans la suite. On se concentre sur le cas des viscosités turbulentes non bornées. Sous des hypothèses compatibles avec la physique 3D, on montre l'existence de solutions scalaires (sans terme de pression) et dans des ouverts périodiques avec une estimation L∞ sur l'énergie cinétique turbulente nous permettant d'utiliser les Lemmes de De Rham classiques pour le terme de pression. Ces résultats ont fait l'objet des publications retranscrites en annexe.
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24

Zhang, Xinlei. "Optimisation de la modélisation RANS d'écoulements cavitants." Thesis, Paris, ENSAM, 2019. http://www.theses.fr/2019ENAM0060.

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Des écoulements cavitants turbulents se produisent dans de nombreuses applicationspratiques telles que les pompes et les propulseurs navals. Dans ces dispositifs, l'implosion des bulles decavitation combinée à des instabilités à différentes échelles engendrent des effets nuisibles majeurscomme des fluctuations du débit, du bruit, des vibrations et de l'érosion. Il est donc essentiel de prédirecorrectement ces instabilités, afin de réduire leurs conséquences. Pour simuler les écoulements cavitantsturbulents, l'approche la plus couramment utilisée est « Reynolds Averaged Navier-Stokes » (RANS)couplée à des modèles de cavitation homogènes, en raison du faible coût de calcul. Cependant, il estgénéralement admis que les modèles RANS ne sont pas précis pour les écoulements caractérisés par desgradients de pression adverses conduisant à des séparations et des recirculations. Cette limitation conduità la mauvaise prédiction des interactions entre la cavitation et la turbulence. Par conséquent, il estnécessaire de quantifier et de réduire les incertitudes dans les modèles RANS, pour améliorer lesperformances prédictives, soit par une approche empirique, soit par des méthodes d’assimilation dedonnées (DA). Dans cette thèse, nous étudions les performances de différentes méthodes pour desécoulements turbulents dans le but final de les appliquer aux écoulements cavitants. Plus précisément, uneméthode hybride variationnelle d’ensemble est appliquée pour reconstruire le champ d’écoulement dansun canal convergent-divergent, en déduisant une vitesse optimale d’entrée et des corrections de modèle àpartir de données d’observation. En outre, nous avons proposé une méthode de Kalman d’ensemblerégularisée, capable d’appliquer des contraintes de régularisation pour des problèmes inverses mal posés.En outre, diverses méthodes d’assimilation d’ensembles sont évaluées pour la quantification del'incertitude dans les applications CFD. Enfin, une nouvelle modification empirique de la viscositéturbulente est proposée pour les écoulements cavitants sur la base de mesures expérimentales
Turbulent cavitating flows occur in many engineering practical applications such as pumpsand propellers. In these devices, the collapse of the cavitation bubbles combines with instabilities atmultiple scales produce major detrimental effects like flow rate fluctuations, noise, vibrations, anderosion. It is thus essential to accurately predict the behavior of unsteady cavitation, thereby reducingtheir consequences for the machinery. To simulate the turbulent cavitating flows, the most commonlyused approach is still the Reynolds-averaged Navier-Stokes (RANS) method coupled with homogeneouscavitation models, due to its computational tractability. However, it is a consensus that the RANS modelsare not accurate for the complex flows in the presence of adverse pressure gradients leading to flowseparation and recirculation. This limitation leads to the poor prediction on the interactions betweencavitation and turbulence in cavitating flows. Hence, it is necessary to quantity and reduce theuncertainties in the RANS model and thus improve the predictive performance, either with an empiricalapproach or data assimilation (DA) methods. In this thesis, we investigate the applicability of suchmethods for turbulent flows with the objective of introducing the data-driven method into cavitatingflows. Specifically, we first apply the hybrid DA method, ensemble based variational method, toreconstruct the flow field in convergent-divergent channel, through inferring optimal inlet velocity andmodel corrections from observation data. Further, we proposed a regularized ensemble Kalman methodcapable of enforcing the regularization constraints for ill-posed inverse problems. Also, variousensemble-based DA methods are evaluated for uncertainty quantification in CFD applications. Finally, anew empirical modification of the turbulent viscosity is proposed for cavitating flows based onexperimental measurements
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25

Mozaffari, Sajad. "Adaptive Grid Refinement for Hybrid RANS/LES." Thesis, Ecole centrale de Nantes, 2020. http://www.theses.fr/2020ECDN0009.

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Les modèles hybrides RANS/LES, qui utilisent les capacités des modèles RANS et LES, conviennent pour la simulation d’écoulements à nombre de Reynolds élevé avec des phénomènes physiques et des géométries complexes. Pourtant, en raison de la dépendance du comportement de ces modèles par rapport à la taille locale des mailles, la génération de maillages avec une bonne résolution est cruciale. Pour une simulation hybride RANS/LES complexe, la génération du maillage est une étape qui demande un effort important. Un processus de raffinement adaptatif est une alternative intéressante, mais nécessite la prise en compte des effets du changement de maillage sur la performance du modèle. Cette thèse porte sur le développement du raffinement adaptatif de maillage basé sur du moyennage et son intégration dans le solveur fluide ISIS-CFD. Le but est d’obtenir un maillage adapté ayant une topologie globalement statique, qui suit les caractéristiques principales de l’écoulement. Premièrement, la dépendance des modèles hybrides RANS/LES par rapport aux modifications du maillage et l’effet d’une interface de raffinement sur la production et la destruction de turbulence sont étudiés. Ensuite, un moyennage en temps des solutions instantanées basé sur différents intervalles est effectué pour filtrer les fluctuations dans la solution moyenne, en fonction des fréquences caractéristiques de l’écoulement. Une procédure de raffinement est ensuite développée, basée sur deux stratégies de moyennage des critères de raffinement instantanés: le moyennage dans une fenêtre glissante et le moyennage sur la totalité du temps de calcul. Le processus d’adaptation proposé est évalué en effectuant une simulation DDES d’un navire en dérive, afin de reproduire la solution sur un maillage fin de référence. L’adaptation basée sur la moyenne réussit à reproduire les principales caractéristiques de l’écoulement et crée des maillages raffinés stables autour des tourbillons principaux. Ainsi, l’approche adaptative constitue une alternative au processus manuel de génération de maillage pour les simulations hybrides RANS/LES, en particulier avec des géométries complexes
Taking advantage of the capabilities of RANS and LES models, hybrid RANS/LES models are suitable for the simulation of high Reynolds number flow with complex physical phenomena and geometries. However, due to the dependency of the behavior of these models on the local grid size, the generation of mesh with the right resolution is crucial. For a complex hybrid RANS/LES simulation, the mesh generation is a time- and effort-consuming step. An adaptive refinement process is an attractive alternative, but requires the consideration of mesh change effects on the performance of the model. This thesis focuses on the development of adaptive grid refinement based on averaging and its integration in the ISISCFD flow solver. The aim is to obtain an adapted mesh whichhasagenerallystatictopologybasedonthemainflow features. First, the dependency of hybrid RANS/LES models on the mesh changes and the effect of a refinement interface on the turbulence production and destruction are considered. Then, time-averaging of the instantaneous solutions over various intervals is carried out to filter the flow fluctuations in the mean solution based on the frequencies of the flow features. A refinement procedure is then developed based on two averaging strategies over instantaneous refinement criteria: the sliding window averaging, and the averaging over the whole computational time. The proposed adaptation process is assessed by performing a DDES-based simulation of a ship in drift in order to reproduce the solution on a reference fine mesh. The average-based adaptation successfully follows the main flow features and creates stable refined grids around the main vortices. Thus, the adaptive approach can be an alternative for the manual mesh generation process of hybrid RANS/LES simulations, especially with complex geometries
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26

Chen, Yi-Ju. "Distribution results for certain tests based on ranks /." free to MU campus, to others for purchase, 1997. http://wwwlib.umi.com/cr/mo/fullcit?p9841272.

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27

Léonard, Thomas. "Étude des approches de modélisation de la turbulence pour la simulation numérique d’un compresseur centrifuge à fort taux de pression." Thesis, Toulouse, ISAE, 2014. http://www.theses.fr/2014ESAE0029/document.

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Cette étude a pour objectif d’étudier différentes approches de modélisation de la turbulence sur un compresseur centrifuge industriel à fort taux de pression afin d’essayer d’élargir notre compréhension des différents phénomènes physiques mis en jeu et leur interaction avec la turbulence. D’abord, la sensibilité au maillage et au modèle turbulence est évalué sur des calculs RANS. Une analyse de simulations LES est ensuite effectuée. En particulier, une étude de l’effet de la turbulence sur l’écoulement et une comparaison aux résultats RANS et expérimentaux est réalisée. Enfin, deux approches hybrides DES sont étudiées afin d’exposer les problèmes rencontrés par ces modèles sur cette configuration. Il en résulte une évaluation des différentes méthodes et de leur applicabilité future dans un contexte industriel
This study aims to assess the abilities of existing numerical simulation methods to predict the complex physical phenomena occurring in an industrial centrifugal compressor and especialy the effect of turbulence on the different flow features. RANS simulations are first performed using various turbulence model, then LES simulations and finally, two simulations using RANS/LES hybrid models of DES type are carried out. The whole compressor operating range is simulated using RANS, but because of LES and DES high computational costs, attention is focussed on the nominal operating point. Particular care is devoted to determine the impact of grid refinement on the simulation results. To this end, simulations are performed on three grids, respectively composed of over 8, 26 and 165 million cells. Even though the grids used do not fulfill the mesh refinement criteria recommended in the litterature for an accurate wall-resolved LES simulation, the simulation performed on the denser grid provides interesting conclusions on the turbulence generation and its interaction with the mean flow.The hybrid DES approches used involve a shield function to prevent the boundary layers to be computed in LES. However, this function is found to be unsuited to this centrifugal compressor flow. Indeed, the RANS and LES regions are not correctly located and most of the tip leakage flow is resolved using a RANS approach, preventing the development of turbulence.This work allowed us to evalute the various approches and highlight some of the problems and advantages of each for the simulation of this centrifugal compressor
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28

Felis-Carrasco, Francisco. "Atomisation et dispersion d'un jet liquide : approches numérique et expérimentale." Thesis, Ecole centrale de Marseille, 2017. http://www.theses.fr/2017ECDM0001/document.

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L'atomisation d'un jet circulaire d'eau typique des applications agricoles est présentée dans cette étude. Maîtriser la dispersion de l'eau à des fins d'irrigation ou de traitements phytosanitaires implique de réduire la consommation d’eau et la pollution de l'environnement. Un cas d'étude simplifié est construit : une buse ronde dn=1.2 mm et d'une longueur Ln=50dn y est considérée. La vitesse d'injection est fixée à UJ=35 m/s et alignée avec la gravité, plaçant le jet liquide dans un régime d'atomisation turbulent. L'écoulement est statistiquement axisymétrique. L'approche est à la fois expérimentale et numérique.Un modèle multiphasique Eulérien de mélange décrit l'écoulement constitué de deux phases. Plusieurs modèles de turbulence U-RANS sont utilisés: k-ε et RSM. Une attention particulière est alors portée à la modélisation des effets de masse volumique variable issus de la formulation du fluide de mélange. Un solveur numérique spécifique est développé à l'aide du code CFD OpenFOAM. Une série de cas d'étude est construite pour tester l'influence de la modélisation de la turbulence et des fermetures de premier/second-ordre des flux massiques turbulents.Les techniques optiques (LDV et DTV) sont déployées pour recueillir des informations statistiques des phases liquide et gazeuse du spray. La campagne expérimentale est réalisée de x/dn=0 jusqu'à x/dn=800. En ce qui concerne la LDV, des gouttelettes d'huile d'olive (~1 µm) permettent d'analyser la phase gazeuse. Une distinction entre les gouttes de liquide et ces traceurs est obtenue par une configuration spécifique de la source laser et le paramétrage de la détection des bouffées Doppler (Filtre-BP et le SNR). Dans la zone dispersée, les mesures par DTV permettent d'estimer les vitesses et les tailles des gouttes. Une attention particulière est portée à l'estimation de la profondeur de champ (DOF) afin d'obtenir une corrélation taille-vitesse des gouttes moins biaisée.Les résultats numériques et expérimentaux concordent pour le champ de vitesse moyenne. Une forte dépendance au modèle de turbulence est trouvée. Cependant, le modèle RSM ne simule pas le comportement du tenseur de Reynolds. En effet, ni l'anisotropie trouvée expérimentalement (R22/R11≈0.05), ni la vitesse de glissement liquide-gaz ne peuvent être reproduites; même avec une fermeture au 2nd-ordre des flux massiques turbulents. Le fort rapport de masse volumique (eau/air), la directionnalité de l'écoulement et la production d'énergie cinétique turbulente peuvent être à l'origine d'une faible dispersion et d'un faible mélange entre les deux fluides. Ce mécanisme n'est pas encore clarifié du point de vue de la modélisation RSM
A typical water round-nozzle jet for agricultural applications is presented in this study. The dispersion of a liquid for irrigation or pesticides spraying is a key subject to both reduce water consumption and air pollution. A simplified study case is constructed to tackle both scenarios, where a round dn=1.2 mm nozzle of a length Ln=50dn is considered. The injection velocity is chosen to be UJ=35 m/s, aligned with gravity, placing the liquid jet in a turbulent atomization regime. The flow is considered statistically axisymmetric. Experimental and numerical approaches are considered.An Eulerian mixture multiphase model describes the original two-phase flow. Several U-RANS turbulence models are used: k-ε and RSM; where special attention is taken to the modelling of variable density effects from the mixture formulation. A custom numerical solver is implemented using the OpenFOAM CFD code. A series of study cases are constructed to test the influence of the turbulence modeling and first/second-order closures of the turbulent mass fluxes. LDV and DTV optical techniques are used to gather statistical information from both the liquid and the gas phases of the spray. The experimental campaign is carried out from x/dn=0 to x/dn=800. Concerning the LDV, small (~1 µm) olive-oil tracers are used to capture the gas phase, where a distinction between the liquid droplets and tracers is achieved by a specific set-up of the laser power source and the burst Doppler setting (BP-Filter and SNR). On the dispersed zone, DTV measurements are carried out to measure velocities and sizes of droplets. Special attention to the depth-of-field (DOF) estimation is taken in order to obtain a less biased droplet’s size-velocity correlation.Numerical and experimental results show good agreement on the mean velocity field. A strong dependence on the turbulence model is found. However, the RSM does not capture the same behaviour on the calculated Reynolds stresses. Indeed, neither the experimental anisotropy (R22/R11≈0.05), nor the liquid-gas slip-velocity can be reproduced, even with a second-order closure for the turbulent mass fluxes. The strong density ratio (water/air), flow’s directionality and production of turbulent kinetic energy may be the cause of a weak dispersion and mixing between the two fluids. This mechanism is not yet clarified from a RSM modeling point-of-view
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29

Friess, Christophe. "Modélisation hybride RANS / LES temporelle des écoulements turbulents." Phd thesis, Université de Poitiers, 2010. http://tel.archives-ouvertes.fr/tel-00598800.

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En situation industrielle, le calcul des caractéristiques instationnaires et tridimensionnelles d' écoulements complexes, est souvent nécessaire. La simulation des grandes échelles requiert un coût de calcul prohibitif surtout près de parois. L'un des objectifs des méthodes hybrides est d'optimiser le coût de calcul, en simulant certaines zones d'un écoulement en mode RANS et d'autres en mode LES. Cette dernière s'articule en géné́ral autour du filtrage spatial, alors que dans la plupart des écoulements, l'opérateur RANS correspond à une moyenne temporelle. L'approche PITM (Partially Integrated Transport Model ), conçue en turbulence homogène, est une méthode hybride justifié́e thé́oriquement. Sa transposition au contexte temporel (turbulence stationnaire) a déjà été explorée précédemment, montrant que, sous certaines hypothèses, les versions spatiale et temporelle sont formellement identiques. La méthode PITM présente toutefois une certaine difficulté à piloter le niveau de résolution. La présente thèse propose une approche dynamique pour corriger ce point. Dans un second temps, la version temporelle du PITM, le T -PITM, est comparé à la DES (Detached Eddy Simulation), une méthode hybride populaire, mais empirique. Il est montré que les deux méthodes produisent des résultats similaires, conférant une justification théorique par procuration, à la DES. Le modèle RANS sous-jacent est la pondération elliptique, permettant la prise en compte des effets induits par une paroi, sans utiliser de fonctions d'amortissement ni de lois de paroi.
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30

Dow, Eric Alexander. "Quantification of structural uncertainties in RANS turbulence models." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/68407.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2011.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 69-70).
This thesis presents an approach for building a statistical model for the structural uncertainties in Reynolds averaged Navier-Stokes (RANS) turbulence models. This approach solves an inference problem by comparing the results of RANS calculations to direct numerical simulation. The adjoint method is used to efficiently solve an inverse problem to determine the RANS turbulent viscosity field that most accurately reproduces the mean flow field computed by direct numerical simulation. The discrepancy between the inferred turbulent viscosity and the turbulent viscosity predicted by RANS is modeled as a Gaussian random field. Finally, the uncertainty in the turbulent viscosity field is propagated to the quantities of interest. Results are first presented for turbulent flow through a straight channel. To model the uncertainty in more complex flows, the procedure is repeated for a collection of flows through randomly generated geometries.
by Eric Alexander Dow.
S.M.
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31

Li, Jinghua. "Hybrid RANS/LES modelling of OGV/prediffuser flow." Thesis, Loughborough University, 2012. https://dspace.lboro.ac.uk/2134/9481.

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In the gas turbine engine, the OGV/prediffuser combination is key to achieve a good design for combustor external aerodynamics. Since the flow includes 3D turbulent wakes and boundary layers in adverse pressure gradients with the possibility of flow separation, the OGV/prediffuser combination offers significant turbulence modelling challenges for CFD. In order to understand the optimum approach for modelling turbulence in this important sub-component of compressor/combustor interaction, a comparison is reported in this thesis with available experimental data for both a conventional and an advanced OGV/prediffuser combination using (i) both high Re and low Re RANS CFD, (ii) LES CFD, and (iii) hybrid RANS/LES CFD. In the hybrid RANS/LES CFD, a new method based on the use of an Algebraic Stress Model and a modified Recycling and Rescaling method has been developed to generate a spatially and temporally correlated unsteady velocity field for the LES inlet conditions from the time-averaged RANS solution at OGV exit. The results show that: 1)Both high Re and low Re RANS solutions show good agreement with the experimental data for the OGV wake prediction, but high Re RANS provides better predictions of overall pressure loss and is certainly more cost effective considering computing costs. 2) The LES solution shows partial flow separation of the OGV suction side boundary layer prediction which was not noted in the experiment. This is probably caused by the presence of relaminarisation and subsequent transition of the suction side OGV boundary layer. This places high demands on the LES near wall mesh required, as well as providing an extreme challenge for the LES sub grid scale model. 3) The Hybrid RANS/LES approach is able to provide a good balance of predictive capability, matching RANS predictions on global performance (pressure rise/loss) and improving the prediction of velocity distribution at prediffuser exit, and it thus offers an optimum approach for OGV/prediffuser flow simulation considering both accuracy and cost.
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32

Azarpeyvand, Mahdi. "Some aspects of RANS based jet noise prediction." Thesis, University of Southampton, 2008. https://eprints.soton.ac.uk/66622/.

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33

Poulain, Arthur. "RANS & WMLES Simulations of Compressor Corner Separation." Thesis, KTH, Mekanik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-279819.

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In axial compressor, corner separation phenomenon can occur between the blade surface and the hub. This leads to high total pressure losses, blockage and may worsen to surge. Various studies on NACA65-009 blade were previously performed experimentally and numerically to predict the corner separation. The LMFA showed that RANS simulations tend to overestimate it while the Wall-Resolved LES (WRLES) was able to well capture it. The conclusions drawn on RANS are validated here with another solver software. An extensive parametric study is performed on RANS which highlights the good performance of two non-linear turbulence models k − ω Wilcox QCR and EARSM k − kl for for predicting the topology and the intensity of corner separation. They are however very dependent on the mesh and the numerics. A Wall-Modeled LES (WMLES) is then computed. It reproduces well the topology of the separation given by the experiments and predicts similar anisotropy to the WRLES. Nevertheless it shows high sensitivity to the level of turbulence close to the endwall and the boundary layer profile of the upstream flow. Finally, this confirms that the WMLES is a promising alternative to the WRLES in order to study the corner separation on more costly geometries (several blades for instance).
I axiell kompressor kan hörnseparationsfenomen uppstå mellan bladytan och navet. Konsekvenserna är stora totala tryckförluster och kompressor blockering. Olika studier på NACA65-009 bladet utfördes tidigare experimentellt och numeriskt för att förutsäga hörnseparationen. LMFA visade att RANS simuleringar tenderar att överskatta den hörnseparationen medan Vägg-Löst LES (WRLES på engelska) kunde fånga bra den. Slutsatserna som dras om RANS valideras här med en annan lösningsprogramvara. En omfattande parametrisk studie utförs på RANS som belyserde goda prestandan för två icke-linjära turbulensmodeller k − ω Wilcox QCRoch EARSM k − kl för att förutsäga topologin och intensiteten för hörnseparation. Dock är de mycket beroende av nät och numerik. En Vägg-Modell LES (WMLES på engelska) beräknas sedan. Det reproducerar väl topologin för separationen som ges av experimenten och förutsäger liknande anisotropi som WRLES. Dock visar det hög känslighet för turbulensnivån nära ändväggen och gränsskiktsprofilen för uppströmsflödet. Slutligen bekräftar detta att WMLES är ett lovande alternativ till WRLES för att studera hörnseparationen på dyrare geometrier (till exempelflera blad).
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Bouvattier, Marc-Antoine. "Unstructured mesh adaptation for turbo-machinery RANS computation." Thesis, KTH, Flygdynamik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-211161.

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This paper gives an overview of the mathematical and practical tools that can be used in turbo-machinery RANS simulation to realize unstructured mesh adaptation. It first presents the concept of metric and recalls that the hessian of the physical flow properties can become, thanks to small modifications, both a metric and a upper bound of the P1 projection error. The resulting metric is then studied on a simple 2D case. In a second part, the industrial application of this concept is addressed and the tools used to overcome the turbo-machinery specificities are explained. Finally, some 2D and 3D results are presented.
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35

Duan, Jiuding. "Predicting with Structured Data: Graphs, Ranks, and Time Series." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/265211.

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京都大学
新制・課程博士
博士(情報学)
甲第23439号
情博第769号
新制||情||131(附属図書館)
京都大学大学院情報学研究科知能情報学専攻
(主査)教授 鹿島 久嗣, 教授 山本 章博, 教授 阿久津 達也
学位規則第4条第1項該当
Doctor of Informatics
Kyoto University
DFAM
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36

Aumelas, Vivien. "Modélisation des hydroliennes à axe vertical libres ou carénées : développement d'un moyen expérimental et d'un moyen numérique pour l'étude de la cavitation." Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00635123.

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Cette thèse s'inscrit dans le cadre des énergies renouvelables au sein du programme HARVEST centré sur le développement d'un concept d'hydrolienne dérivé des turbines Darrieus et Gorlov. L'ajout d'un dispositif appelé carénage à la turbine permet à celle-ci d'extraire une portion de l'énergie cinétique du courant plus grande. Toutefois ce dernier peut favoriser la cavitation qui nuit à la turbine. Parmi les différents axes du programme, les travaux de thèse se situent dans cette problématique. En régime subcavitant et cavitant, l'analyse de l'hydrolienne a été menée suivant une approche numérique et expérimentale. Pour ce faire deux outils ont été mis en place. Du coté expérimental, le tunnel hydrodynamique du LEGI a été équipé d'une balance qui donne la mesure instantanée des forces et du couple qui s'exercent sur la turbine. Du coté numérique, les efforts ont été orientés sur l'amélioration et le développement du code de calcul universitaire, CAVKA. L'utilisation intensive de ces deux moyens, couplée à des modèles théoriques, a permis de mettre en évidence d'une part le fonctionnement de la turbine libre ou carénée et, d'autre part, les limites de fonctionnement vis-à-vis de la cavitation.
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37

Ruan, S. "Turbulent partially premixed combustion : DNS analysis and RANS simulation." Thesis, University of Cambridge, 2013. https://www.repository.cam.ac.uk/handle/1810/244504.

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Increasingly stringent regulation of pollutant emission has motivated the search for cleaner and more efficient combustion devices, which remain the primary means of power generation and propulsion for all kinds of transport. Fuel-lean premixed combustion technology has been identified to be a promising approach, despite many difficulties involve, notably issues concerning flame stability and ignitability. A partially premixed system has been introduced to remedy these problems, however, our understanding on this combustion mode needs to be greatly improved to realise its full potential. This thesis aims to further the understanding of various fundamental physical processes in turbulent partially premixed flames. DNS data of a laboratory-scale hydrogen turbulent jet lifted flame is analysed in this study. The partially premixed nature of this flame is established by examining the instantaneous and averaged reaction rates and the "Flame Index", which indicate premixed and diffusion burning modes coexisting. The behaviour of turbulent flame stretch and its relation to other physical processes, in particular the scalar-turbulence interaction, the effects of partial premixing on the displacement speed of iso-scalar surface and its correlation with the surface curvature are explored using DNS data. The scalar gradient alignment characteristics change from aligning with the most compressive strain to aligning with the most extensive one in regions of intensive heat release. This alignment change creates negative normal strain rate which can result in negative surface averaged tangential strain rate. The partial premixing affects the flame surface displacement speed through the mixture fraction dissipation rate and a second derivative in the mixture fraction space. The correlation of curvature and displacement speed is found to be negative in general and the effects of partial premixing act to reduce this negative correlation. The combined effects of the normal strain rate and the displacement speed/curvature correlation contribute to the negative mean flame stretch observed in the flame brush. Scalar dissipation rates (SDR) of the mixture fraction ẼZZ, progress variable Ẽcc and their cross dissipation rates (CDR) ẼcZ are identified as important quantities in the modelling of partially premixed flames. Their behaviours in the lifted flame stabilisation region are examined in a unified framework. It is found that SDR of mixture fraction is well below the quenching value in this region while SDR of progress variable is smaller than that in laminar flames. The CDR changes from weakly positive to negative at the flame leading edge due to the change in scalar gradient alignment characteristics. Axial and radial variation of these quantities are analysed and it is found that Ẽcc is an order of magnitude bigger than ẼZZ. ẼcZ is two orders of magnitude smaller than Ẽcc and it can be either positive or negative depending on local flow and flame conditions. Simple algebraic models show reasonable agreement compared to DNS when a suitable definition of c is used. Further statistics of the scalar gradients are presented and a presumed lognormal distribution is found to give reasonable results for their marginal PDFs and a bivariate lognormal distribution is a good approximation for their joint PDF. Four mean reaction rate closures based on presumed PDF and flamelets are assessed a priori using DNS data. The turbulent flame front structure is first compared with unstrained and strained laminar premixed and dif fusion flamelets. It is found that unstrained premixed flamelets give overall reasonable approximation in most parts of this flame. A joint PDF model which includes the correlation between mixture fraction and progress variable using a "copula" method shows excellent agreement with DNS results while their statistical independence does not hold in the burning regions of this partially premixed flame. The unstrained premixed flamelet with the correlated joint PDF method is identified to be the most appropriate model for the lifted jet flame calculation. This model is then used in the RANS simulation of turbulent jet lifted flames. A new model to include the contribution from diffusion burning and the effects of partial premixing due to SDR of mixture fraction is also identified and included in the calculation. These models are implemented in a commercial CFD code "Fluent" with user defined scalars and functions. It is found that both the correlated joint PDF model and the model accounting for the diffusive burning in partial premixing are important in order to accurately predict flame lift-off height compared to the experiments.
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38

De, Prisco Giuseppe. "Hybrid RANS LES simulation of non-equilibrium boundary layers." College Park, Md. : University of Maryland, 2007. http://hdl.handle.net/1903/6813.

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Thesis (Ph. D.) -- University of Maryland, College Park, 2007.
Thesis research directed by: Mechanical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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39

Knight, Kyle Cohn Davis. "Assessment of RANS Turbulence Models for Strut-Wing Junctions." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/31760.

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Multidisciplinary Design Optimization (MDO) studies show the Strut/Truss Braced Wing (SBW/TBW) concept has the potential to save a significant amount of fuel over conventional designs. For the SBW/TBW concept to achieve these reductions, the interference drag at the wing strut juncture must be small compared to other drag sources. Computational Fluid Dynamics (CFD) studies have concluded the interference drag is small enough for the TBW concept to be practical. However, the turbulence models used in these studies have not been validated for transonic, high Reynolds number, junction flows. This study intends to assess turbulence models by comparing drag and surface streamlines obtained from experiment and CFD. The test model is a NACA 0012 fin at Mach number of 0.75 and a Reynolds number of 6 million with varying angle of attack. The CFD analysis includes both the fin and tunnel test section. The main turbulence model tested is the k-w Shear Stress Transport model. The fin is tested at different Mach numbers and inlet conditions to account for experimental variations. The study shows the CFD over predicts separation. The reasons for this discrepancy is likely the turbulence models employed.
Master of Science
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40

DeSena, Geoffrey. "Improvement of RANS Forest Model via Closure Coefficient Modification." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-326514.

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As wind farms continue to take up more land throughout Northern Europe, developers are looking to sparsely populated areas, particularly in northern Fennoscandia, which hosts strong winds but also mixed and patchy forests over complex terrain. The complexity makes wind resource assessments difficult, raising uncertainty and therefore cost. Computational fluid dynamics (CFD) has the potential to increase the accuracy and reliability of wind models, but the most common form of commercial CFD modeling, Reynolds averaged Navier-Stokes (RANS), makes limiting assumptions about the effect of the forest on the wind. The wind resource assessment and energy estimation tool WindSim® , developed by WindSim AS, utilizes a porous medium model of a homogeneous forest with the influence of the forest on the airflow as a drag force term in the momentum equations. This method has provided reliable wind speed results but has been less reliable in estimating turbulence characteristics. The measure we evaluate in this study is turbulence intensity (TI). In this investigation, we make two types of modifications to the model and evaluate their impact on the TI estimates by using a benchmark data set collected by Meroney [1]. The first method is a variable profile of leaf area index (LAI) to represent the physical shape of the forest more accurately, and the second is a series of modifications to the closure coefficients in the turbulence transport equations. These modifications focus on the work of Lopes et al. [2], who used a large eddy simulation (LES) model to show that the turbulence production terms originally proposed by Green [3], expanded upon by Sanz [4], and widely used in the industry are unnecessary. Our investigations found that the implementation of a variable LAI profile has a small but non-negligible effect and that the elimination of the production terms from the turbulence transport equations does lead to a significant reduction in TI immediately above the forest. Both methods have minor effects on wind speed estimates, but the modification of closure coefficients has a much more significant impact on the TI. The coefficients proposed by Lopes et al. [2] drastically reduce TI estimates, but the model is still unable to reflect the Meroney data throughout the forest. Continued modification to new closure coefficients in combination with a variable forest LAI and other modifications such as a limited length scale may lead to significant improvement in TI estimates in future models, but these modifications must be compared against real-world data to ensure their applicability.
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41

Rajamani, Bharanidharan. "Hybrid RANS-LES modeling of High-Re turbulent flows." Diss., Restricted to subscribing institutions, 2008. http://proquest.umi.com/pqdweb?did=1779690381&sid=14&Fmt=2&clientId=48051&RQT=309&VName=PQD.

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42

Ploé, Patrick. "Surrogate-based optimization of hydrofoil shapes using RANS simulations." Thesis, Ecole centrale de Nantes, 2018. http://www.theses.fr/2018ECDN0012/document.

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Cette thèse présente un framework d’optimisation pour la conception hydrodynamique de forme d’hydrofoils. L’optimisation d’hydrofoil par simulation implique des objectifs d’optimisation divergents et impose des compromis contraignants en raison du coût des simulations numériques et des budgets limités généralement alloués à la conception des navires. Le framework fait appel à l’échantillonnage séquentiel et aux modèles de substitution. Un modèle prédictif est construit en utilisant la Régression par Processus Gaussien (RPG) à partir des données issues de simulations fluides effectuées sur différentes géométries d’hydrofoils. Le modèle est ensuite combiné à d’autres critères dans une fonction d’acquisition qui est évaluée sur l’espace de conception afin de définir une nouvelle géométrie qui est testée et dont les paramètres et la réponse sont ajoutés au jeu de données, améliorant ainsi le modèle. Une nouvelle fonction d’acquisition a été développée, basée sur la variance RPG et la validation croisée des données. Un modeleur géométrique a également été développé afin de créer automatiquement les géométries d’hydrofoil a partir des paramètres déterminés par l’optimiseur. Pour compléter la boucle d’optimisation,FINE/Marine, un solveur fluide RANS, a été intégré dans le framework pour exécuter les simulations fluides. Les capacités d’optimisation ont été testées sur des cas tests analytiques montrant que la nouvelle fonction d’acquisition offre plus de robustesse que d’autres fonctions d’acquisition existantes. L’ensemble du framework a ensuite été testé sur des optimisations de sections 2Dd’hydrofoil ainsi que d’hydrofoil 3D avec surface libre. Dans les deux cas, le processus d’optimisation fonctionne, permettant d’optimiser les géométries d’hydrofoils et confirmant les performances obtenues sur les cas test analytiques. Les optima semblent cependant être assez sensibles aux conditions opérationnelles
This thesis presents a practical hydrodynamic optimization framework for hydrofoil shape design. Automated simulation based optimization of hydrofoil is a challenging process. It may involve conflicting optimization objectives, but also impose a trade-off between the cost of numerical simulations and the limited budgets available for ship design. The optimization frameworkis based on sequential sampling and surrogate modeling. Gaussian Process Regression (GPR) is used to build a predictive model based on data issued from fluid simulations of selected hydrofoil geometries. The GPR model is then combined with other criteria into an acquisition function that isevaluated over the design space, to define new querypoints that are added to the data set in order to improve the model. A custom acquisition function is developed, based on GPR variance and cross validation of the data.A hydrofoil geometric modeler is also developed to automatically create the hydrofoil shapes based on the parameters determined by the optimizer. To complete the optimization loop, FINE/Marine, a RANS flow solver, is embedded into the framework to perform the fluid simulations. Optimization capabilities are tested on analytical test cases. The results show that the custom function is more robust than other existing acquisition functions when tested on difficult functions. The entire optimization framework is then tested on 2D hydrofoil sections and 3D hydrofoil optimization cases with free surface. In both cases, the optimization process performs well, resulting in optimized hydrofoil shapes and confirming the results obtained from the analytical test cases. However, the optimum is shown to be sensitive to operating conditions
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43

Menier, Victorien. "Numerical methods and mesh adaptation for reliable rans simulations." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066481/document.

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Cette thèse porte sur la prédiction haute-fidélité de phénomènes visqueux turbulents modélisés par les équations Reynolds-Averaged Navier-Stokes (RANS). Si l’adaptation de maillage a été appliquée avec succès aux simulations non-visqueuses comme la prédiction du bang sonique ou la propagation d’explosion, prouver que ces méthodes s’étendent et s’appliquent également aux simulations RANS avec le même succès reste un problème ouvert. Dans ce contexte, cette thèse traite des problématiques relatives aux méthodes numériques (solveur de mécanique des fluides) et aux stratégies d’adaptation de maillage. Pour les méthodes numériques, nous avons implémenté un modèle de turbulence dans notre solveur et nous avons conduit une étude de vérification et validation en deux et trois dimensions avec comparaisons à l’expérience. Des bons résultats ont été obtenus sur un ensemble de cas tests, notamment sur le calcul de la traînée pour des géométries complexes. Nous avons également amélioré la robustesse et la rapidité de convergence du solveur, grâce à une intégration en temps implicite, et grâce à une procédure d’accélération multigrille. En ce qui concerne les stratégies d’adaptation de maillage, nous avons couplé les méthodes multigrilles à la boucle d’adaptation dans le but de bénéficier des propriétés de convergence du multigrille, et ainsi, améliorer la robustesse du processus et le temps CPU des simulations. Nous avons également développé un algorithme de génération de maillage en parallèle. Celui-ci permet de générer des maillages anisotropes adaptés d’un milliard d’éléments en moins de 20 minutes sur 120 coeurs de calcul. Enfin, nous avons proposé une procédure pour générer automatiquement des maillages anisotropes adaptés quasi-structurés pour les couches limites
This thesis deals with the high-fidelity prediction of viscous turbulent flows modelized by the Reynolds-Averaged Navier-Stokes (RANS) equations. If mesh adaptation has been successfully applied to inviscid simulations like the sonic boom prediction or the blast propagation, demonstrating that these methods are also well-suited for 3D RANS simulations remains a challenge. This thesis addresses research issues that arise in this context, which are related to both numerical methods (flow solver) and mesh adaptation strategies. For the numerical methods, we have implemented a turbulence model in our in-house flow solver and carried out its verification & validation study. Accurate results were obtained for a representative set of test cases, including the drag prediction workshop. Additional developments have been done to improve the robustness and the convergence speed of the flow solver. They include the implementation of an implicit time integration and of a multigrid acceleration procedure. As regards mesh adaptation, we have coupled the adaptive process to multigrid in order to benefit from its convergence properties and thus improve the robustness while preventing losses of computational effort. We also have devised a parallel mesh generation algorithm. We are able to generate anisotropic adapted meshes containing around one billion elements in less than 20min on 120 cores. Finally, we introduced a procedure to automatically generate anisotropic adapted quasi-structured meshes in boundary layer regions
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44

Didorally, Sheddia. "Prévision des flux de chaleur turbulents et pariétaux par des simulations instationnaires pour des écoulements turbulents chauffés." Thesis, Toulouse, ISAE, 2014. http://www.theses.fr/2014ESAE0015/document.

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Cette thèse s’inscrit dans le cadre de l’amélioration des prévisions aérothermiques qui suscite l’intérêt croissant des industriels aéronautiques. Elle consiste à évaluer l’apport des méthodes URANS avancées de type SAS dans la prévision des flux de chaleur turbulents et pariétaux pour des écoulements turbulents chauffés. Elle vise aussi à situer ces approches par rapports aux modèles URANS classiques de type DRSM et hybrides RANS/LES comme la ZDES. Une extension de l’approche SAS à un modèle DRSM a d’abord été proposé afin d’obtenir une meilleure restitution des tensions de Reynolds résolues et modélisées. Ce modale SAS-DRSM a été implanté dans le code elsA de l’ONERA. Nous avons ensuite évalué les approches SAS disponibles avec ce code sur la prévention d’écoulements aérothermiques rencontrés sur avion dans un compartiment de moteur. Ces études ont montré que les approches SAS améliorent la représentation des écoulements par rapport aux modèles URANS classiques. Elles aboutissent à des écoulements fortement tridimensionnels avec de nombreuses structures turbulentes. Ces structures induisent un mélange turbulent accru et donc une meilleure prévision du flux de chaleur pariétal. De plus, nos travaux ont situé les approches de type SAS comme des méthodes plus précises que les méthodes URANS classiques sans augmentation importante du coût de calcul. Les modèles SAS ne résolvent pas les plus petites structures caractéristiques du mouvement turbulent par rapport à la ZDES qui montre des prévisions supérieures. Le modèle SAS-RDSM offre néanmoins la meilleur alternative de type SAS. Enfin, l’étude du flux de chaleur turbulent semble retrouver le fait que l’hypothèse classique de nombre de Prandtl turbulent constat n’est pas valable dans toutes les zones de l’écoulement
The improvement of aerothermal predictions is a major concern for aeronautic manufacturers. In line with this issue, SAS approaches are assessed on the prediction of wall and turbulent heat fluxes for heated-turbulent flows. This study also aims at evaluating these advanced URANS methods in regard to DRSM models and hybrid RANS/LES approaches as ZDES. Firstly, we proposed to combine the SAS approach and a DRSM model in order to better reproduce both resolved and modelled Reynolds stresses. This new model, called SAS-DRSM, was implemented in ONERA Navier-Strokes code elsA. Unsteady simulations of two heated turbulent flows encountered in an aircraft engine compartment were then performed to evaluate all the SAS models available in the code. These numerical studies demonstrated that SAS approaches improve prediction of the flows compared to classical URANS models. They lead to full 3D flows with many turbulent structures. These structures favour turbulent mixing and thus induce a better prediction of the wall heat fluxes. Moreover, the numerical simulations showed that SAS methods are more accurate than classical URANS models without increasing significantly calculation costs. SAS approaches are not able to resolve the smallest turbulent structures in relation to ZDES which provides better predictions. Finally, the investigation of the turbulent heat flux suggested that the constant turbulent Prendtl number assumption, that is characteristic of classical URANS models, may not be valid in some regions of the flow
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45

Seelinger, Matthew J. "Breaking ranks : veterans' opposition to universal military training, 1943-1948." Virtual Press, 1996. http://liblink.bsu.edu/uhtbin/catkey/1033637.

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From the colonial period to the present, Americans have debated the role of the military and its place in American society. One important part of this debate is the issue of compulsory military service and whether it is consistent with the ideals of a democratic state. Although Americans have generally accepted compulsory service in times of national emergency, they have often expressed great reservations to it in times of peace. In their view, compulsory military service raises fundamental questions about the responsibilities of citizens to the state.Following World War II, proponents of compulsory military service campaigned for implementation of Universal Military Training (UMT) as a method of insuring manpower for a potential national emergency. By stressing the universal aspect of the program, supporters hoped to demonstrate the democratic qualities of UMT and its compatibility with traditional American ideals. Ultimately, however, they were unable to convince Congress and the general public of the program's merits. Some opposed the program because of its questionable military value in the atomic age. Many others voiced their disapproval of UMT largely because of a longstanding American sentiment against peacetime compulsory service. As a result, UMT was never implemented.This thesis will explore a neglected aspect of the UMT debate and examine the opposition of veterans to UMT. Veterans generally, and veterans organizations in particular, have traditionally advocated military preparedness. Not surprisingly, the American Legion was the primary nongovernmental organization to spearhead the effort to adopt UMT. Yet significant opposition to UMT existed even within the Legion's ranks. Similarly, the American Veterans Committee (AVC), a newly formed organization comprised of World War II veterans, announced its opposition to military training. With uncertain support from a segment of American society that would normally be expected to back preparedness programs, the government's plan for military training had little chance for adoption. With the resumption of selective service in 1948, the importance of UMT to U.S. military policy greatly diminished, and UMT virtually disappeared from the political forefront.Through the use of archival sources at the American Legion National Headquarters, the records of the American Veterans Committee, congressional testimony by representatives of both organizations, and various secondary sources, this thesis demonstrates that some veterans, like many Americans, viewed peacetime compulsory military service with great ambivalence and not an obligation of citizenship in a democratic state.
Department of History
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46

Abdalatif, Fatma Alzahra. "In Search of Home; Child Soldiers in al-Shabaab's Ranks." Thesis, Linnéuniversitetet, Institutionen för statsvetenskap (ST), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-106943.

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A history of fragility and conflicts in Somalia has had severe impact on the security of citizens, most notably children. Different non-state actors and armed militias have appeared in Somalia’s timeline impacting the region’s, neighboring and global security. The prevalence of child soldiers in Somalia is alarming and so is the presence of armed groups that regularly recruit them. This paper focuses on studying the causes of child recruitment from a human security lens, examining the impact of fragility in Somalia and the ways by which one particular group; al- Shabaab exploits the fragile environment to recruit children. Qualitative data from different online sources is analyzed indicating that the instability in Somalia and the recruitment of children remain closely interlinked, and human security and development in the region are compromised by corruption, poor governance, societal division, ongoing conflicts and displacement.
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47

Yu, Kai. "Level-set RANS method for sloshing and green water simulations." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-2097.

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48

labourasse, emmanuel. "Reconstruction des fluctuations turbulentes par une approche hybride RANS/LES." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2002. http://tel.archives-ouvertes.fr/tel-00006002.

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Les méthodes actuelles de calcul instationnaire des équations de Navier-Stokes (Simulation Numérique Directe (SND), Simulation des Grandes Echelles (SGE)) demandent encore un temps de calcul excessif pour pouvoir être utilisées à des fins industrielles. D'autre part, les méthodes statistiques (RANS) moins coûteuses, ne permettent pas de rendre compte des phénomènes à large bande fréquentielle, qui sont à l'origine, par exemple, des ondes acoustiques. Le développement de méthodes localement couplées permet de concilier les avantages des deux types d'approches précités (SGE et RANS). Une méthode originale de ce type à été développée sur la base de la Non-Linear Disturbance Equations (NLDE). Elle consiste à résoudre l'intégralité du champ grâce à un calcul statistique. Ensuite, aux endroits critiques, le complément fréquentiel est calculé en SGE, de manière à enrichir le champ. Le code a été implanté sur le NEC SX5 de l'ONERA et testé sur plusieurs cas d'application en incompressible (canal plan bi-périodique) et en compressible (aube de turbomachine, aile hypersustentée). Ses possibilités ont été testées et des conditions limites spécifiques ont été développées. La méthode se comporte bien dans tous ces cas d'application et peut être utilisée de façon locale, permettant ainsi une nette réduction du temps de calcul.
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49

Makowka, Konrad [Verfasser]. "Numerically Efficient Hybrid RANS/LES of Supersonic Combustion / Konrad Makowka." München : Verlag Dr. Hut, 2016. http://d-nb.info/1084385236/34.

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50

Patel, Alpesh K. "Développement d'un solveur RANS adaptatif sur maillages non-structurés hexaédriques." Doctoral thesis, Universite Libre de Bruxelles, 2003. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/211338.

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