Spelling suggestions: "subject:"compound A"" "subject:"eompound A""
651 |
Vliv různého hospodaření na produkci, strukturu a chemické složení nadzemní biomasy v povodí Mlýnského potoka / Effect of different management on the production, structure and chemical composition of abovegroung biomass in the Mlýnský potok catchment.TRUHLÁŘ, Martin January 2015 (has links)
The aim of the thesis is to assess the changes in production and structure of surface biomass (the proportion of grasses, clovers and other plants) and its chemical compound in scythed and pastured grass areas in the monitored areas in the Mlýnský potok basin in years 2012 and 2014. The area is situated on the right bank of Lipno dam in Pasečná land register, 784 820 meters above sea-level. There were established three permanent sampling points in the pastured as well as scythed areas in the Mlýnský potok basin. Four samples of biomass from the area of 1 sq m were collected in each of these sampling points. These were collected on 20th June 2012, 11th September 2012, 17th June 2014 and 10th September 2014. The collected biomass was then divided into agro-botanical groups (grasses, clovers and other plants) and afterwards it was dried and weighed. The chemical analysis was conducted by a certified laboratory AGRO-LA, Ltd. in Jindřichův Hradec. The aim of the analysis was to find out the amount of nitrogen, phosphorus, potassium, magnesium and calcium. By assessing the development of the overall production of the biomass in 2012 and 2014 in the sampling area we found out a considerable decline of biomass in scythed areas and an increasing difference in the average amount of biomass between scythed and pastured areas during the monitored period. These findings were assessed as statistically conclusive. By assessing the development of overall proportions of the agro-botanical groups we could see a substantial decrease in grasses and on the other hand an increase of clovers and other plants in scythed areas compared to pastured areas. The difference between the proportion of grasses and other plants proved to be statistically conclusive. By assessing the development in difference of the overall average amount of nitrogen in the biomass, there emerged a considerable increase in the amount of nitrogen regardless the way of management. As far as phosphorus is concerned, we found out a decreasing difference in its amount between scythed and pastured areas. The amount of potassium was considerably lower in scythed areas, whereas calcium showed the exact opposite. Statistically conclusive were the findings of substantial increase of nitrogen in the surface biomass and also the changes in the amount of potassium and calcium due to the management. By evaluating these outcomes we confirmed that the permanent grass areas have a very variable productive and structural potential which holds true also for their chemical compound.
|
652 |
Análise experimental e numérica de escoamentos turbulentos em canais compostos empregando simulação de grandes escalas e método dos elementos finitos / Experimental and numerical analysis of turbulent flows in compound channels employing large eddy simulation and the finite element methodXavier, Carla Marques January 2013 (has links)
Este trabalho apresenta um estudo experimental e numérico de escoamentos em canais compostos. Simulação de grandes escalas e método dos elementos finitos, em paralelo com medições utilizando anemômetros de fio quente em um canal aerodinâmico são realizadas. Canais compostos estão presentes em muitas aplicações de engenharia. Dispositivos eletrônicos, trocadores de calor, reatores nucleares, canais de irrigação e planícies de inundação são alguns dos desafios enfrentados pela engenharia. A combinação de simulação de grandes escalas e o método dos elementos finitos para a investigação de escoamentos turbulentos pode ser de grande importância para o estudo dos escoamentos na engenharia. No caso dos escoamentos através dos canais compostos, publicações neste tema são ainda raros. Os principais objetivos deste trabalho são: analisar o escoamento de um fluido viscoso, incompressível e isotérmicas em um canal composto, empregando um código de computação tridimensional apresentado por Petry em 2002, que realiza simulação de grandes escalas com o método dos elementos finitos, para comparar os resultados numéricos com os resultados experimentais do escoamento turbulento em um canal composto cuja geometria é exactamente reproduzida pela malha numérica, para verificar a validade do método numérico e o comportamento de modelos em escala subgrade para reproduzir o fluxo no canal composto investigado; e comparar a eficácia dos esquemas Taylor-Galerkin e dois passos para analisar os resultados. O canal investigado consiste em um canal principal com seção transversal retangular, conectado a uma fenda retangular estreita. No código numérico, o modelo clássico de Smargorinsky é comparado com o modelo dinâmico de viscosidade turbulenta, inicialmente proposto por Germano et al. 1991. A segunda filtragem do processo dinâmico é feita através dos elementos finitos independentes propostos por Petry, 2002. Para a implementação do algoritmo, o método dos elementos finitos é usado, Taylor-Galerkin e esquemas dois passos são usados para a discretização no tempo e no espaço e de ligação das equações governantes. O domínio computacional é discretizadas por intermédio de elementos lineares hexaédricos. Os resultados obtidos a partir simulações de grandes escalas, usando o modelo clássico de Smagorinsky e o modelo dinâmico de submalha; mostram o desenvolvimento de uma camada de cisalhamento na direção principal do escoamento com características dinâmicas regidas pelos perfis de velocidade média. Os resultados da simulação mostraram boa concordância com os dados experimentais dos perfis de velocidade média, intensidade de turbulência e tensão de cisalhamento turbulenta. Em geral, o modelo dinâmico com o esquema de duis passos foi mais eficiente para reproduzir estruturas turbulentas, em comparação com o modelo Smagorinsky e o esquema Taylor-Galerkin particularmente ao longo da região da fenda do canal. / This work presents an experimental and numerical study of turbulent flows in compound channels. Large eddy simulation and finite element method in parallel with hot wires measurements in an aerodynamic channel are employed. Compound channels are present in many engineering applications like in electronic devices, heat exchangers, nuclear reactors and irrigation channels and flooding plains are some of the challenges faced by mechanical engineering. The combination of large eddy simulation and the finite element method for the investigation of turbulent flows can be of great relevance to the study of engineering flows. In the case of flows through compound channels, publications in this subject are still rare. The main objectives in this work are: to analyze the flow of viscous, incompressible and isothermal fluids in a compound channel; employing a three-dimensional computation code presented by Petry, 2002, which performs large eddy simulation with the finite element method; to compare the numerical results with experimental results of the turbulent flow in a compound channel whose geometry is exactly reproduced by the numerical mesh; to check the validity of the numerical method and the behavior of subgrid scale models to reproduce the flow in the compound channel investigated and compare the efficacy of the Taylor-Galerkin and Two-Steps schemes in analyzing the results. The compound channel investigated consists of a rectangular channel connected to a rectangular shaped slot. In the numerical code, Smargorinsky´s classical model is compared to the dynamic model of turbulent viscosity, initially proposed by Germano et al. The second filtering of the dynamic process is made through the independent finite elements proposed by Petry, 2002. For the implementation of the algorithm, the finite element method is used, Taylor- Galerkin and Two-Steps schemes are used for discretization in time and space and to link governing equations. The computational domain is discretized by means of linear hexahedrical elements. The results obtained from large eddy simulations, using the classical model of Smagorinsky and the Dynamic subgrid scale model show the development of a shear layer in the main direction of flow with dynamic characteristics governed by the mean velocity profiles. The simulation results showed good agreement compared to experimental data, and analysis of the profiles of mean velocity, turbulence intensities and turbulent shear stress. In general, dynamic model with the two-steps scheme was more able to reproduce turbulent structures in comparison with the Smagorinsky model with Taylor-Galerkin scheme, particularly along the channel slot.
|
653 |
Synthèse totale et évaluation biologique d’un inhibiteur d’origine naturelle de la kinase DYRK1A / Total synthesis and biological evaluation of natural inhibitor of DYRK1A kinaseLucas, Romain 06 November 2014 (has links)
Les travaux de la thèse se sont articulés autour de la synthèse totale d’un composé naturel isolé à partir de la plante Scorzoneraradiata, la RCZ. Lors d’un criblage sur un panel de kinases, dont la kinase DYRK1A, les résultats ont montré la très grande sélectivité de ce composé avec une action d’inhibition sur DYRK1A (IC50 = 220 nM). De nombreuses études disponibles dans la littérature ont établi le lien entre la dérégulation de la protéine DYRK1A avec le syndrome de Down (trisomie 21) et certaines maladies neurodégénératives tel que la maladie d’Alzheimer. En vue de l’obtention de ce composé prometteur présentant un squelette dihydrostilbène porteur d’une fonction cétone et d’un groupement osidique. Trois voies d’approche ont été successivement mises en œuvre. Le groupement cétone est construit par le biais d’une réaction de Sonogashira suivit par une hydratation en présence d’un sel mercurique. La réaction de Wittig permet l’assemblage du squelette stilbène. Lors de la première approche, un isomère de position du composé final avec un pouvoir inhibiteur divisé par dix par rapport à RCZ a été obtenu. L’utilisation de différents groupements protecteurs a permis l’obtention du composé final RCZ en seulement 15 étapes. Ce travail ouvre de nouvelles perspectives dans le développement d’analogues par des pharmacomodulations en se basant sur les informations fournies par le co-cristal de RCZ avec la protéine DYRK2. / This thesis focuses on the synthesis of RCZ, a natural compound isolated from the plant Scorzonera radiata. During a high-throughput screening, this compound has demonstrated, on a large panel of kinases, a high and unusual degree of selectivity against the kinase DYRK1A. On a structural point of view, the compound is a glycosylated dihydrostlibene, which also bears two phenols and an acetyl group. Recently, a link between the deregulation of the kinase DYRK1A with Down syndrom and some neurodegenerative diseases such as Alzheimer disease has been established. In order to perform the synthesis of this compound, three approaches were undertaken. In these approaches, the acetyl group was built through a Sonogashira coupling followed by a mercury salt catalyzed hydration of the acetylenic group. Also, the stilbene scaffold was always obtained by Wittig condensdation. In the first approach, an isomer was obtained with approximately a ten times less potent inhibitory activity against DYRK1A than RCZ. By the use of different protective groups the final compound RCZ was successfully obtained. In conclusion, a total and efficient synthesis of RCZ has been constructed in 15 steps. This work opens future perspective in the design of new inhibitors based on the determination of the crystal structure of the RCZ-DYRK2 complex.
|
654 |
Multiple Radar Target Tracking in Environments with High Noise and ClutterJanuary 2015 (has links)
abstract: Tracking a time-varying number of targets is a challenging
dynamic state estimation problem whose complexity is intensified
under low signal-to-noise ratio (SNR) or high clutter conditions.
This is important, for example, when tracking
multiple, closely spaced targets moving in the same direction such as a
convoy of low observable vehicles moving through a forest or multiple
targets moving in a crisscross pattern. The SNR in
these applications is usually low as the reflected signals from
the targets are weak or the noise level is very high.
An effective approach for detecting and tracking a single target
under low SNR conditions is the track-before-detect filter (TBDF)
that uses unthresholded measurements. However, the TBDF has only been used to
track a small fixed number of targets at low SNR.
This work proposes a new multiple target TBDF approach to track a
dynamically varying number of targets under the recursive Bayesian framework.
For a given maximum number of
targets, the state estimates are obtained by estimating the joint
multiple target posterior probability density function under all possible
target
existence combinations. The estimation of the corresponding target existence
combination probabilities and the target existence probabilities are also
derived. A feasible sequential Monte Carlo (SMC) based implementation
algorithm is proposed. The approximation accuracy of the SMC
method with a reduced number of particles is improved by an efficient
proposal density function that partitions the multiple target space into a
single target space.
The proposed multiple target TBDF method is extended to track targets in sea
clutter using highly time-varying radar measurements. A generalized
likelihood function for closely spaced multiple targets in compound Gaussian
sea clutter is derived together with the maximum likelihood estimate of
the model parameters using an iterative fixed point algorithm.
The TBDF performance is improved by proposing a computationally feasible
method to estimate the space-time covariance matrix of rapidly-varying sea
clutter. The method applies the Kronecker product approximation to the
covariance matrix and uses particle filtering to solve the resulting dynamic
state space model formulation. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2015
|
655 |
Atividade antinociceptiva do geraniol: estudos comportamentaise eletrofisiológicosLa Rocca, Viviana 29 February 2016 (has links)
Submitted by Leonardo Cavalcante (leo.ocavalcante@gmail.com) on 2018-07-17T18:53:07Z
No. of bitstreams: 1
Arquivototal.pdf: 3232624 bytes, checksum: 559aa25bbe9205467b3fdd737354219e (MD5) / Made available in DSpace on 2018-07-17T18:53:07Z (GMT). No. of bitstreams: 1
Arquivototal.pdf: 3232624 bytes, checksum: 559aa25bbe9205467b3fdd737354219e (MD5)
Previous issue date: 2016-02-29 / The high incidence of pain in the general population has encouraged research about this
theme. Products derived from plant species have been widely used in the
pharmacological treatment of pain relief. Recent studies have reported the important
role of monoterpenes, active compounds found in the essential oils of aromatic plants,
having relevant analgesic and anti-inflammatory potential. The geraniol (GER) is a
monoterpenic alcohol, found in >160 essential oil of plant species, especially
Cymbopogon gender. In the literature consulted, several biochemical and
pharmacological properties are shown of GER: antitumor, antimicrobial, antiinflammatory,
antioxidant, gastric and intestinal protector, neuroprotective and
antiarrhythmic. In this study was evaluated the antinociceptive activity of GER, not yet
reported, by animal behavioral and electrophysiological in vitro models. Male and
female adult Swiss mice were used. Initially the acute toxicity of GER was investigated
by calculating the lethal dose 50 (LD50) by intraperitoneal (i.p.) (= 199.9 mg/kg) and
oral (p.o.) (> 1 g/kg). In psychopharmacological screening, after the administration of
single doses of GER (i.p. and p.o.), behavioral changes were observed indicating a
depressant profile on the central nervous system (CNS) and/or peripheral nervous
system (SNP), and relevant antinociceptive effect of geraniol. Therefore, more specific
antinociceptive property evaluation tests were performed. The GER (12.5, 25 or 50
mg/kg i.p. and 50 or 200 mg/kg p.o.) decreased (p<0.001) the number of abdominal
contractions induced by i.p. injection of acetic acid, when compared with the control.
The opioid antagonist naloxone (5 mg/kg) administered subcutaneously (s.c.) in mice,
subsequently treated with GER (25 mg/kg i.p.), did not reverse its antinociceptive
activity. The GER (12.5, 25 and 50 mg/kg i.p.) reduced (p<0.001) paw licking time in
the second phase (15-30 min, inflammatory phase) of the formalin test. Also, in the
glutamate test was reduced (p<0.01) paw licking time when GER 50 mg/kg i.p.
administered. In a subsequent step, it was investigated the effect of GER on the
excitability of peripheral nerve fibers through extracellular recording in the sciatic nerve
in mice. The GER presented depressant effect of the compound action potential (CAP),
which was reversed after washing and recovery period. The GER blocked components
of the CAP concentration-dependent manner and exposure time to the drug: 1 mM after
120 min for the first component (Aγ and Aβ fibers) and 0.6 mM after 90 min for the
second (Aγ and Aδ fibers). The concentration, which induces 50% inhibition of the
peak-to-peak amplitude of the PAC (IC50) for the GER was calculated, being equal to
0.48±0.04 mM. The conduction velocity was also reduced by exposure to GER from the
0.3 mM concentration, for the 1st component [46.18±2.60 m/s to 36.04±1.60 m/s;
p<0.05 (n=7)] and the 2nd component [18.37±1.31 m/s to 12.71±0.56 m/s; p<0.001
(n=7)]. In conclusion, the results obtained show that GER has antinociceptive activity,
mainly in pain related to inflammation. Participation of the opioid pathway in its
mechanism of action is unlikely, but the modulation of glutamatergic neurotransmission
in a dose-dependent manner is a possible mechanism. Its antinociceptive activity is also
related to the reduction in peripheral neuronal excitability, firstly in thinner fibers Aδ,
which are directly connected to the conduction pain. / A elevada incidência da dor na população em geral tem incentivado as pesquisas
entorno desse tema. Produtos oriundos de espécies vegetais têm sido amplamente
utilizados no tratamento farmacológico de alívio da dor. Estudos recentes têm relatado o
importante papel dos monoterpenos, princípios ativos encontrados nos óleos essenciais
de plantas aromáticas, tendo relevante potencial analgésico e anti-inflamatório. O
geraniol (GER) é um álcool monoterpênico, encontrado no óleo essencial de >160
espécies vegetais, especialmente do gênero Cymbopogon. Na literatura consultada,
pesquisas apontam várias propriedades bioquímicas e farmacológicas para o GER:
antitumoral, antimicrobiana, anti-inflamatória, antioxidante, de proteção gástrica e
intestinal, neuroprotetora e antiarrítmica. Neste estudo foi avaliada a atividade
antinociceptiva do GER, ainda não relatada, mediante modelos animais
comportamentais e eletrofisiológicos in vitro. Foram utilizados camundongos machos e
fêmeas Swiss adultos. Inicialmente, foi investigada a toxicidade aguda do GER
mediante cálculo da dose letal 50 (DL50) pela via intraperitoneal (i.p.) (=199,9 mg/kg) e
oral (v.o.) (>1 g/kg). Na triagem psicofarmacológica, após a subministração de doses
únicas de GER (i.p. e v.o.) foram observadas alterações comportamentais que indicaram
perfil depressor do sistema nervoso central (SNC) e/ou periférico (SNP), e relevante
efeito antinociceptivo do geraniol. Portanto, foram realizados testes comportamentais de
avaliação de propriedade antinociceptiva mais específicos. O GER (12,5; 25 e 50 mg/kg
i.p. e 50 ou 200 mg/kg v.o.) reduziu (p<0,001) o número de contorções abdominais
induzidas por injeção i.p. de ácido acético, quando comparado com o controle. O
antagonista opióide naloxona (5 mg/kg) administrado pela via subcutânea (s.c.) em
camundongos, subsequentemente tratados com GER (25 mg/kg i.p.), não reverteu sua
atividade antinociceptiva. O GER (12,5; 25 e 50 mg/kg i.p.) reduziu (p<0,001) o tempo
de lambida da pata na segunda fase (15-30 min, fase inflamatória) do teste da formalina.
Também, no teste do glutamato houve redução (p<0,01) do tempo de lambida da pata
quando administrado GER 50 mg/kg i.p. Em uma etapa subsequente, investigou-se o
efeito do GER sobre a excitabilidade de fibras nervosas periféricas, mediante registro
extracelular em nervo ciático de camundongo. O GER apresentou efeito depressor do
potencial de ação composto (PAC), o qual foi parcialmente revertido após lavagem
durante o período de recuperação. O GER bloqueou as componentes do PAC, de
maneira dependente da concentração e do tempo de exposição à droga: 1 mM aos 120
min para a primeira componente (fibras Aγ e Aβ) e 0,6 mM aos 90 min para a segunda
(fibras Aγ e Aδ). Foi calculada para o GER, a concentração que induz 50% de inibição
da amplitude pico-a-pico do PAC (CI50), sendo igual a 0,48±0,04 mM. A velocidade de
condução também, foi reduzida pela exposição ao GER, a partir da concentração de 0,3
mM para a 1ª componente [46,18±2,60 m/s para 36,04±1,60 m/s; p<0,05 (n=7)] e para a
2ª componente [18,37±1,31 m/s para 12,71±0,56 m/s; p<0,001 (n=7)]. Em conclusão, os
resultados obtidos mostram que o GER tem atividade antinociceptiva, principalmente na
dor relacionada à inflamação. A participação da via opióide no seu mecanismo de ação é
pouco provável, mas a modulação da neurotransmissão glutamatérgica de maneira
dependente da dose é um mecanismo possível. Sua atividade antinociceptiva tambèm,
está relacionada à redução da excitabilidade neuronal periférica, primeiramente de
fibras mais finas como Aδ, ligadas diretamente à condução da dor.
|
656 |
Desenvolvimento de pastas cimentantes utilizando cimentos portland compostos para cimenta??o de po?os petrol?ferosBel?m, Francisco Ademir Teles 11 October 2010 (has links)
Made available in DSpace on 2014-12-17T14:08:48Z (GMT). No. of bitstreams: 1
FranciscoATB_DISSERT.pdf: 170574 bytes, checksum: 1c8ab112e2d611ca8a276251605aaaa3 (MD5)
Previous issue date: 2010-10-11 / The Compound Portland cements are commonly used in construction, among them
stand out the CPII-Z, CPII-F and CPIV. These types of cement have limited application
on oil well cementing, having its compositional characteristics focused specifically to
construction, as cement for use in oil wells has greater complexity and properties
covering the specific needs for each well to be coated. For operations of oil wells
cementing are used Portland cements designed specifically for this purpose. The
American Petroleum Institute (API) classifies cements into classes designated by letters
A to J. In the petroleum industry, often it is used Class G cement, which is cement that
meets all requirements needed for cement from classes A to E. According to the
scenario described above, this paper aims to present a credible alternative to apply the
compound cements in the oil industry due to the large availability of this cement in
relation to oil well cements. The cements were micro structurally characterized by
XRF, XRD and SEM tests, both in its anhydrous and hydrated state. Later technological
tests were conducted to determine the limits set by the NBR 9831. Among the
compound cements studied, the CPII-Z showed satisfactory properties for use in
primary and secondary operations of oil wells up to 1200 meters cementing / Os cimentos Portland Compostos s?o comumente utilizados na constru??o civil, dentre
eles destacam-se os CPII-Z, CPII-F e o CPIV. Estes tipos de cimento t?m sua aplica??o
limitada para cimenta??o de po?os de petr?leo, tendo em vista suas caracter?sticas
composicionais direcionadas especificamente para a constru??o civil. Cimentos para uso
em po?os de petr?leo possuem uma maior complexidade e propriedades que d?o suporte
?s necessidades especificas para cada po?o a ser revestido. Para as opera??es de
cimenta??o de po?os petrol?feros, s?o usados cimentos Portland desenvolvidos
especialmente para tal finalidade de acordo com as normas API (American Petroleum
Institute), os quais s?o classificados por classes, designadas pelas letras de A a J. Na
ind?stria do petr?leo, comumente se utiliza o cimento da classe G, por ser um cimento
que atende praticamente todas as condi??es previstas para os cimentos das classes A at?
E. De acordo com o cen?rio descrito acima, esse trabalho teve como objetivo apresentar
uma alternativa confi?vel para aplica??o de cimentos compostos na ind?stria do
petr?leo em fun??o da grande disponibilidade destes cimentos em rela??o aos cimentos
petrol?feros. Os cimentos foram caracterizados microestruturalmente atrav?s de ensaios
de FRX, DRX e MEV, tanto em seu estado anidro quanto hidratado. Posteriormente,
foram realizados ensaios tecnol?gicos para determinar os limites estabelecidos pela
norma NBR 9831. Dentre os cimentos compostos estudados, o cimento CPII-Z
apresentou propriedades satisfat?rias para aplica??o em opera??es de cimenta??o
prim?ria e secund?ria de po?os petrol?feros at? 1200 metros
|
657 |
Análise experimental e numérica de escoamentos turbulentos em canais compostos empregando simulação de grandes escalas e método dos elementos finitos / Experimental and numerical analysis of turbulent flows in compound channels employing large eddy simulation and the finite element methodXavier, Carla Marques January 2013 (has links)
Este trabalho apresenta um estudo experimental e numérico de escoamentos em canais compostos. Simulação de grandes escalas e método dos elementos finitos, em paralelo com medições utilizando anemômetros de fio quente em um canal aerodinâmico são realizadas. Canais compostos estão presentes em muitas aplicações de engenharia. Dispositivos eletrônicos, trocadores de calor, reatores nucleares, canais de irrigação e planícies de inundação são alguns dos desafios enfrentados pela engenharia. A combinação de simulação de grandes escalas e o método dos elementos finitos para a investigação de escoamentos turbulentos pode ser de grande importância para o estudo dos escoamentos na engenharia. No caso dos escoamentos através dos canais compostos, publicações neste tema são ainda raros. Os principais objetivos deste trabalho são: analisar o escoamento de um fluido viscoso, incompressível e isotérmicas em um canal composto, empregando um código de computação tridimensional apresentado por Petry em 2002, que realiza simulação de grandes escalas com o método dos elementos finitos, para comparar os resultados numéricos com os resultados experimentais do escoamento turbulento em um canal composto cuja geometria é exactamente reproduzida pela malha numérica, para verificar a validade do método numérico e o comportamento de modelos em escala subgrade para reproduzir o fluxo no canal composto investigado; e comparar a eficácia dos esquemas Taylor-Galerkin e dois passos para analisar os resultados. O canal investigado consiste em um canal principal com seção transversal retangular, conectado a uma fenda retangular estreita. No código numérico, o modelo clássico de Smargorinsky é comparado com o modelo dinâmico de viscosidade turbulenta, inicialmente proposto por Germano et al. 1991. A segunda filtragem do processo dinâmico é feita através dos elementos finitos independentes propostos por Petry, 2002. Para a implementação do algoritmo, o método dos elementos finitos é usado, Taylor-Galerkin e esquemas dois passos são usados para a discretização no tempo e no espaço e de ligação das equações governantes. O domínio computacional é discretizadas por intermédio de elementos lineares hexaédricos. Os resultados obtidos a partir simulações de grandes escalas, usando o modelo clássico de Smagorinsky e o modelo dinâmico de submalha; mostram o desenvolvimento de uma camada de cisalhamento na direção principal do escoamento com características dinâmicas regidas pelos perfis de velocidade média. Os resultados da simulação mostraram boa concordância com os dados experimentais dos perfis de velocidade média, intensidade de turbulência e tensão de cisalhamento turbulenta. Em geral, o modelo dinâmico com o esquema de duis passos foi mais eficiente para reproduzir estruturas turbulentas, em comparação com o modelo Smagorinsky e o esquema Taylor-Galerkin particularmente ao longo da região da fenda do canal. / This work presents an experimental and numerical study of turbulent flows in compound channels. Large eddy simulation and finite element method in parallel with hot wires measurements in an aerodynamic channel are employed. Compound channels are present in many engineering applications like in electronic devices, heat exchangers, nuclear reactors and irrigation channels and flooding plains are some of the challenges faced by mechanical engineering. The combination of large eddy simulation and the finite element method for the investigation of turbulent flows can be of great relevance to the study of engineering flows. In the case of flows through compound channels, publications in this subject are still rare. The main objectives in this work are: to analyze the flow of viscous, incompressible and isothermal fluids in a compound channel; employing a three-dimensional computation code presented by Petry, 2002, which performs large eddy simulation with the finite element method; to compare the numerical results with experimental results of the turbulent flow in a compound channel whose geometry is exactly reproduced by the numerical mesh; to check the validity of the numerical method and the behavior of subgrid scale models to reproduce the flow in the compound channel investigated and compare the efficacy of the Taylor-Galerkin and Two-Steps schemes in analyzing the results. The compound channel investigated consists of a rectangular channel connected to a rectangular shaped slot. In the numerical code, Smargorinsky´s classical model is compared to the dynamic model of turbulent viscosity, initially proposed by Germano et al. The second filtering of the dynamic process is made through the independent finite elements proposed by Petry, 2002. For the implementation of the algorithm, the finite element method is used, Taylor- Galerkin and Two-Steps schemes are used for discretization in time and space and to link governing equations. The computational domain is discretized by means of linear hexahedrical elements. The results obtained from large eddy simulations, using the classical model of Smagorinsky and the Dynamic subgrid scale model show the development of a shear layer in the main direction of flow with dynamic characteristics governed by the mean velocity profiles. The simulation results showed good agreement compared to experimental data, and analysis of the profiles of mean velocity, turbulence intensities and turbulent shear stress. In general, dynamic model with the two-steps scheme was more able to reproduce turbulent structures in comparison with the Smagorinsky model with Taylor-Galerkin scheme, particularly along the channel slot.
|
658 |
Variants of compound models and their application to citation analysisLow, Wan Jing January 2017 (has links)
This thesis develops two variant statistical models for count data based upon compound models for contexts when the counts may be viewed as derived from two generations, which may or may not be independent. Unlike standard compound models, the variants model the sum of both generations. We consider cases where both generations are negative binomial or one is Poisson and the other is negative binomial. The first variant, denoted SVA, follows a zero restriction, where a zero in the first generation will automatically be followed by a zero in the second generation. The second variant, denoted SVB, is a convolution model that does not possess this zero restriction. The main properties of the SVA and SVB models are outlined and compared with standard compound models. The results show that the SVA distributions are similar to standard compound distributions for some fixed parameters. Comparisons of SVA, Poisson hurdle, negative binomial hurdle and their zero-inflated counterpart using simulated SVA data indicate that different models can give similar results, as the generating models are not always selected as the best fitting. This thesis focuses on the use of the variant models to model citation counts. We show that the SVA models are more suitable for modelling citation data than other previously used models such as the negative binomial model. Moreover, the application of SVA and SVB models may be used to describe the citation process. This thesis also explores model selection techniques based on log-likelihood methods, Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC). The suitability of the models is also assessed using two diagrammatic methods, randomised quantile residual plots and Christmas tree plots. The Christmas tree plots clearly illustrate whether the observed data are within fluctuation bounds under the fitted model, but the randomised quantile residual plots utilise the cumulative distribution, and hence are insensitive to individual data values. Both plots show the presence of citation counts that are larger than expected under the fitted model in the data sets.
|
659 |
MatemÃtica financeira: o estudo de emprÃstimos consignados e consÃrcios voltados para o ensino mÃdio / Financial mathematics: the study of payroll loans and consortia aimed at high schoolAntonio Sabino de Paula Neto 12 April 2014 (has links)
CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Vive-se em um mundo com muitos recursos computacionais, planilhas grÃficas ou calculadoras financeiras. Tornam-se indiscutÃveis e indispensÃveis que alÃm desses recursos necessitamos, no mÃnimo, dos conceitos bÃsicos da MatemÃtica Financeira, para um entendimento mais apurado do assunto, possibilitando a aplicaÃÃo de cÃlculos financeiros na tomada de decisÃes. O objetivo dessa dissertaÃÃo à mostrar como se comporta os emprÃstimos consignados e os consÃrcios buscando fazer ligaÃÃo imediata com a nossa realidade. / We live in a world with many computational resources, financial spreadsheets or graphical calculators. Become indisputable and indispensable addition to these features we need at least the basic concepts of financial mathematics to a more accurate understanding of the subject, enabling the application of financial calculations in making decisions. The objective of this dissertation is to show how it behaves payroll loans and consortia seeking to make direct connection with our reality.
|
660 |
Análise experimental e numérica de escoamentos turbulentos em canais compostos empregando simulação de grandes escalas e método dos elementos finitos / Experimental and numerical analysis of turbulent flows in compound channels employing large eddy simulation and the finite element methodXavier, Carla Marques January 2013 (has links)
Este trabalho apresenta um estudo experimental e numérico de escoamentos em canais compostos. Simulação de grandes escalas e método dos elementos finitos, em paralelo com medições utilizando anemômetros de fio quente em um canal aerodinâmico são realizadas. Canais compostos estão presentes em muitas aplicações de engenharia. Dispositivos eletrônicos, trocadores de calor, reatores nucleares, canais de irrigação e planícies de inundação são alguns dos desafios enfrentados pela engenharia. A combinação de simulação de grandes escalas e o método dos elementos finitos para a investigação de escoamentos turbulentos pode ser de grande importância para o estudo dos escoamentos na engenharia. No caso dos escoamentos através dos canais compostos, publicações neste tema são ainda raros. Os principais objetivos deste trabalho são: analisar o escoamento de um fluido viscoso, incompressível e isotérmicas em um canal composto, empregando um código de computação tridimensional apresentado por Petry em 2002, que realiza simulação de grandes escalas com o método dos elementos finitos, para comparar os resultados numéricos com os resultados experimentais do escoamento turbulento em um canal composto cuja geometria é exactamente reproduzida pela malha numérica, para verificar a validade do método numérico e o comportamento de modelos em escala subgrade para reproduzir o fluxo no canal composto investigado; e comparar a eficácia dos esquemas Taylor-Galerkin e dois passos para analisar os resultados. O canal investigado consiste em um canal principal com seção transversal retangular, conectado a uma fenda retangular estreita. No código numérico, o modelo clássico de Smargorinsky é comparado com o modelo dinâmico de viscosidade turbulenta, inicialmente proposto por Germano et al. 1991. A segunda filtragem do processo dinâmico é feita através dos elementos finitos independentes propostos por Petry, 2002. Para a implementação do algoritmo, o método dos elementos finitos é usado, Taylor-Galerkin e esquemas dois passos são usados para a discretização no tempo e no espaço e de ligação das equações governantes. O domínio computacional é discretizadas por intermédio de elementos lineares hexaédricos. Os resultados obtidos a partir simulações de grandes escalas, usando o modelo clássico de Smagorinsky e o modelo dinâmico de submalha; mostram o desenvolvimento de uma camada de cisalhamento na direção principal do escoamento com características dinâmicas regidas pelos perfis de velocidade média. Os resultados da simulação mostraram boa concordância com os dados experimentais dos perfis de velocidade média, intensidade de turbulência e tensão de cisalhamento turbulenta. Em geral, o modelo dinâmico com o esquema de duis passos foi mais eficiente para reproduzir estruturas turbulentas, em comparação com o modelo Smagorinsky e o esquema Taylor-Galerkin particularmente ao longo da região da fenda do canal. / This work presents an experimental and numerical study of turbulent flows in compound channels. Large eddy simulation and finite element method in parallel with hot wires measurements in an aerodynamic channel are employed. Compound channels are present in many engineering applications like in electronic devices, heat exchangers, nuclear reactors and irrigation channels and flooding plains are some of the challenges faced by mechanical engineering. The combination of large eddy simulation and the finite element method for the investigation of turbulent flows can be of great relevance to the study of engineering flows. In the case of flows through compound channels, publications in this subject are still rare. The main objectives in this work are: to analyze the flow of viscous, incompressible and isothermal fluids in a compound channel; employing a three-dimensional computation code presented by Petry, 2002, which performs large eddy simulation with the finite element method; to compare the numerical results with experimental results of the turbulent flow in a compound channel whose geometry is exactly reproduced by the numerical mesh; to check the validity of the numerical method and the behavior of subgrid scale models to reproduce the flow in the compound channel investigated and compare the efficacy of the Taylor-Galerkin and Two-Steps schemes in analyzing the results. The compound channel investigated consists of a rectangular channel connected to a rectangular shaped slot. In the numerical code, Smargorinsky´s classical model is compared to the dynamic model of turbulent viscosity, initially proposed by Germano et al. The second filtering of the dynamic process is made through the independent finite elements proposed by Petry, 2002. For the implementation of the algorithm, the finite element method is used, Taylor- Galerkin and Two-Steps schemes are used for discretization in time and space and to link governing equations. The computational domain is discretized by means of linear hexahedrical elements. The results obtained from large eddy simulations, using the classical model of Smagorinsky and the Dynamic subgrid scale model show the development of a shear layer in the main direction of flow with dynamic characteristics governed by the mean velocity profiles. The simulation results showed good agreement compared to experimental data, and analysis of the profiles of mean velocity, turbulence intensities and turbulent shear stress. In general, dynamic model with the two-steps scheme was more able to reproduce turbulent structures in comparison with the Smagorinsky model with Taylor-Galerkin scheme, particularly along the channel slot.
|
Page generated in 0.0467 seconds