481 |
Ultrafast Hydration Dynamics Probed by Tryptophan at Protein Surface and Protein-DNA InterfaceQin, Yangzhong 14 May 2015 (has links)
No description available.
|
482 |
Fundamental Solutions and Numerical Modeling of Internal and Interfacial Defects in Magneto-Electro-Elastic Bi-MaterialsZhao, Yanfei 10 September 2015 (has links)
No description available.
|
483 |
Study of Mechanical Properties of Carbon Nanotubes and Nanocomposites by Molecular SimulationsMokashi, Vineet V. 26 May 2005 (has links)
No description available.
|
484 |
Aqueous Biphasic 3D Cell Culture Micro-TechnologyAtefi, Ehsan January 2015 (has links)
No description available.
|
485 |
Enhanced Dielectric Properties of Multilayer Capacitor Film via Interfacial PolarizationTseng, Jung-Kai 27 January 2016 (has links)
No description available.
|
486 |
Single-molecule interfacial electron transfer dynamics in solar energy conversionDhital, Bharat 17 November 2016 (has links)
No description available.
|
487 |
Homogenization Based Damage Models for Monotonic and Cyclic Loading in 3D Composite MaterialsJain, Jayesh R. 12 January 2009 (has links)
No description available.
|
488 |
[pt] CARACTERIZAÇÃO EXPERIMENTAL DE ONDAS INTERFACIAIS EM ESCOAMENTO ESTRATIFICADO TURBULENTO GÁS-LIQUIDO UTILIZANDO VELOCIMETRIA POR IMAGEM DE PARTÍCULA / [en] EXPERIMENTAL CHARACTERIZATION OF LINEAR INTERFACIAL WAVES IN A STRATIFIED TURBULENT GAS-LIQUID PIPE FLOW USING PARTICLE IMAGE VELOCIMETRYPAULA STOFER CORDEIRO DE FARIAS 19 May 2020 (has links)
[pt] A ocorrência do escoamento slug em tubulações horizontais é de especial
interesse para a indústria de petróleo devido aos riscos operacionais indesejados
associados a esse padrão de escoamento. Portanto, nas últimas décadas um
intenso esforço foi dedicado ao estudo e modelagem do escoamento slug.
Ferramentas preditivas baseadas na estabilidade linear de Kelvin-Helmhotz foram
amplamente desenvolvidas na literatura para prever a transição para esse regime
de escoamento. Esses modelos são derivados da análise de estabilidade modal
de perturbações bem definidas. No entanto, para escoamento em tubulação, um
número bastante limitado de estudos experimentais dedicados para investigação
da evolução de perturbações que originem o regime slug está disponível. Além
disso, estudos a partir da introdução de perturbações bem definidas, que podem
fornecer informações precisas para validação de modelos e simulações
numéricas, foram encontrados. O presente trabalho abordou o problema da
transição para o regime slug a partir da caracterização da evolução de ondas
interfaciais. Essas perturbações controladas foram excitadas com um modo de
geração na interface do escoamento estratificado utilizando uma placa oscilatória.
O trabalho se concentra na caracterização de ondas interfaciais no regime linear,
que corresponde ao regime de estudo da maioria dos modelos disponíveis na
literatura. Portanto, um limiar de amplitude para ondas lineares foi estimado
experimentalmente. O acionamento da placa oscilatória foi sincronizado com as
aquisições de imagens, permitindo medições sincronizadas em fase. As medições
do campo de velocidade foram realizadas usando a técnica de Velocimetria de
Imagem de Partículas (PIV) e Iluminação de Fundo (Shadowgraphy). O perfil de
velocidade e turbulência do escoamento foram medidos simultaneamente nas
fases do liquido e do gás. A sincronização em fase permitiu a extração do perfil de
flutuação de velocidade coerentes as ondas interfaciais. Os resultados obtidos são
originais e mostraram, pela primeira vez na literatura, que os modos interfaciais
em ambas as fases são quase independentes dos modos cisalhantes, dentro da
faixa de parâmetros abordados neste trabalho. A caracterização de ondas não lineares foi brevemente investigada, indicando mudanças no perfil do escoamento
médio. Além disso, foi obtida uma correlação para o fator de atrito das ondas
interfaciais, levando a uma melhoria na estimativa da altura do líquido e da perda
de carga do tubo quando combinadas nas relações de fechamento dos modelos
1-D. A metodologia experimental proposta neste trabalho é uma ferramenta
valiosa para produzir informações precisas que podem ser usadas para validar e
aprimorar modelos teóricos e simulações numéricas. O estudo pode contribuir
para a compreensão dos mecanismos físicos envolvidos na transição do
escoamento estratificado para slug. / [en] The occurrence of slug regime in horizontal pipelines is of special interest for
the oil and gas industry due to the unwanted operational risks associated with this
flow. Hence, an intense effort has been devoted to the study and to model this flow
regime. Predictive tools based on linear Kelvin-Helmhotz stability have been widely
applied in the literature for prediction of slug onset. These models are derived from
stability analysis of well-defined disturbances. However, for pipe flows, a limited
number of experimental studies devoted to investigate the evolution of
disturbances that lead to the initiation of slugs is available. In addition, no studies
are found using of well define disturbances, which could provide accurate
information for validation of models and numerical simulations. The present work
addresses the problem by the studying of the evolution of controlled waves excited
at the liquid interface. To this end, an oscillating paddle was employed. The work
focuses the characterization of interfacial waves within the linear regime, which
correspond to the regime of most models available in the literature. The amplitude
threshold for linear waves was experimentally estimated. The driving signal of the
oscillating paddle was synchronized with image acquisitions, enabling phase
locked measurements of the waves and hence the use of ensemble averaging
techniques. Phase-locked measurements of the velocity field in the liquid and gas
layers were performed using off-axis Particle Image Velocimetry (PIV) technique
and Shadowgraph. Mean flow, streamwise and wall normal fluctuations were
measured simultaneously in the liquid and gas phases. For a range of flow rates
and exciting wave frequencies the combined techniques employed allowed the
extraction from the measured velocity fields, the coherent part of flow fluctuations
related with the exciting waves. The results obtained have shown, seemingly, for
the first time, that interfacial modes in both phases are nearly independent of near
wall disturbances within the range of parameters covered in this work.
Characterization of nonlinear waves was briefly investigated indicating changes in
the mean velocity. Moreover, a correlation for wave friction factor based on wave
and flow parameters was obtained, leading to an improvement on the liquid heightand pipe head loss estimation when are combined into the closure relations used
for the 1-D models. The experimental methodology proposed in this work is a
valuable tool to produce accurate information that can be used to validate and
improve theoretical models and numerical simulations. It can contribute to the
understanding of the physical mechanisms involved in the transition from stratified
to slug flows.
|
489 |
INTERFACE, PHASE CHANGE AND MOLECULAR TRANSPORT IN SUB, TRANS AND SUPERCRITICAL REGIMES FOR N-ALKANE/NITROGEN MIXTURESSuman Chakraborty (13184898) 01 August 2022 (has links)
<p> Understanding the behavior of liquid hydrocarbon propellants under high pressure and temperature conditions is a crucial step towards improving the performance of modern-day combustion engines (liquid rocket engines, diesel engines, gas turbines and so on) and designing the next generation ones. Under such harsh thermodynamic conditions (high P&T) propellent droplets may experience anywhere from sub-to-trans-to-supercritical regime. The focus of this research is to explore the dynamics of the vapor-liquid two phase system formed by a liquid hydrocarbon fuel (n-heptane or n-dodecane) and ambient (nitrogen) over a wide range of P&T leading up to the mixture critical point and beyond. Molecular dynamics (MD) has been used as the primary tool in this research along with other tools like: phase stability calculations based on Gibb’s work, Peng Robinson equation of state, density gradient theory and neural networks.</p>
|
490 |
PHASE FIELD CRYSTAL STUDIES OF STRAIN-MEDIATED EFFECTS IN THE THERMODYNAMICS AND KINETICS OF INTERFACESStolle, Jonathan F. E. 04 1900 (has links)
<p>In this dissertation, the Phase Field Crystal (PFC) Method is used to study a number of problems in which interfaces and elastic effects play important roles in alloys. In particular, the three topics covered in this work are grain boundary thermodynamics in alloys, dislocation-mediated formation of clusters in binary and ternary alloys, and solutal effects in explosive crystallization. Physical phenomena associated with grain boundaries, such as Read-Shockley-like behaviour and Gibbs adsorp- tion theorem, were shown to be accurately captured in both PFC- and XPFC-type models. In fact, a connection between the solute segregation behaviour and physical properties of the system—such as energy of mixing, mismatch, and undercooling—were shown. Also, grain boundary premelting was investigated. It was shown how solute can change the disjoining potential of a grain boundary and a mechanism for hysteresis in grain boundary premelting was discussed. Regarding the phenomenon of cluster formation, a general coexistence approach and a nucleation-like approach were used to describe the mechanism consistently with observations; the process is facilitated by lowering the energy increase associated with it. The final phenomenon studied was explosive crystallization. It was shown that the temperature oscillations due to unsteady motion of an interface could be captured with PFC-type models and that this behaviour leaves patterns, such as solute traces, in the material. The versatility of this PFC formalism was demonstrated by capturing the underlying physics and elucidating the role of misfit strain in altering interface oscillations during explosive crystallization. Finally, it was demonstrated in all projects how PFC model parameters relate to coarse-grained material properties, thereby connecting these phenomena on larger scales to atomistic-scale properties.</p> / Doctor of Philosophy (PhD)
|
Page generated in 0.0558 seconds