Qiu, Can = / Thesis (M.Phil.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 82-87). / Abstracts in English and Chinese. / Qiu, Can = / Abstract --- p.i / 摘要 --- p.ii / Acknowledge --- p.iii / Table of Contents --- p.iv / List of Figures --- p.v i i / List of Tables --- p.xi / Chapter Chapters I --- Introduction --- p.1 / Chapter 1.1 --- Turbulence --- p.1 / Chapter 1.2 --- Rayleigh-Benard convection --- p.3 / Chapter 1.2.1 --- Physics picture-Motion in the convection cell --- p.4 / Chapter 1.2.2 --- The governing equations and parameters --- p.6 / Chapter 1.2.3 --- Multilayer convection --- p.9 / Chapter 1.2.4 --- The Nu scaling --- p.9 / Chapter 1.2.5 --- Boundary layers --- p.11 / Chapter 1.3 --- Present work and the organization of the thesis --- p.14 / Chapter II --- Experimental Setup --- p.16 / Chapter 2.1 --- The convection cell --- p.16 / Chapter 2.2 --- The thermistors --- p.20 / Chapter 2.2.1 --- Calibration --- p.20 / Chapter 2.3 --- The multimeter --- p.21 / Chapter 2.4 --- Thermostat box --- p.22 / Chapter 2.5 --- Visualization --- p.23 / Chapter 2.6 --- Motorized translation stage --- p.24 / Chapter 2.7 --- AC Wheatstone Bridge and Lock in amplifier --- p.24 / Chapter 2.8 --- Test different heaters --- p.26 / Chapter III --- "Heat flux, boundary layer and Reynolds number measurement of one-layer FC77 thermal convection" --- p.30 / Chapter 3.1 --- Heat flux measurement with correction --- p.30 / Chapter 3.1.1 --- Sidewall correction --- p.31 / Chapter 3.1.2 --- Bottom plate correction --- p.31 / Chapter 3.1.3 --- Post correction --- p.31 / Chapter 3.2 --- The Nu result --- p.32 / Chapter 3.3 --- Boundary layer measurement --- p.34 / Chapter 3.4 --- The Pr dependence of the Reynolds number Re --- p.37 / Chapter 3.5 --- Summary --- p.40 / Chapter IV --- "Heat transfer, thermal boundary layer and flow property measurement of multilayer immiscible fluid turbulent thermal convection" --- p.41 / Chapter 4.1 --- Introduction --- p.41 / Chapter 4.2 --- Experiment --- p.44 / Chapter 4.3 --- The temperature and temperature fluctuation across the interface --- p.46 / Chapter 4.3.1 --- The temperature near the interface --- p.46 / Chapter 4.3.2 --- Position and temperature of the interface --- p.47 / Chapter (a) --- Using the profile to get the temperature of the interface --- p.47 / Chapter (b) --- Using the traveling microscope to get the absolute position of the interface --- p.50 / Chapter 4.4 --- The Nu result --- p.50 / Chapter 4.5 --- Boundary layer thickness and scaling --- p.54 / Chapter 4.6 --- Statistical properties of the temperature field across the interface --- p.58 / Chapter 4.6.1 --- Temperature time series and the corresponding histogram of the interface --- p.58 / Chapter 4.6.2 --- "The mean, root mean square, skewness, time derivative skewness and flatness of the temperature profiles across the interface" --- p.64 / Chapter 4.6.3 --- Scaling of the temperature fluctuation in two-layer system --- p.71 / Chapter 4.7 --- The temperature oscillation --- p.74 / Chapter 4.8 --- Passive scalar and active scalar --- p.77 / Chapter 4.9 --- Summary --- p.79 / Chapter V --- Conclusion --- p.80 / Chapter 5.1 --- One-layer thermal convection --- p.80 / Chapter 5.2 --- Two-layer thermal convection --- p.80 / Chapter 5.3 --- Future works --- p.81 / References --- p.82

Chu, Wai Siu = 聚合物添加劑對邊界層流動中熱傳輸量的影響 / 朱瑋韶. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 67-68). / Abstracts in English and Chinese. / Chu, Wai Siu = Ju he wu tian jia ji dui bian jie ceng liu dong zhong re chuan shu liang de ying xiang / Zhu Weishao. / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- Background --- p.3 / Chapter 3 --- Formulation of the problem --- p.9 / Chapter 3.1 --- Prandtl-Blasius equations with temperature field --- p.9 / Chapter 3.2 --- The evolution equation for Rij --- p.15 / Chapter 3.3 --- Equations of motion with polymers --- p.19 / Chapter 3.4 --- Nusselt number and drag coefficient --- p.26 / Chapter 4 --- Results and discussion --- p.29 / Chapter 4.1 --- Obtaining the converged solutions --- p.29 / Chapter 4.2 --- Studying different parameters --- p.38 / Chapter 4.3 --- The parameter a --- p.54 / Chapter 5 --- Summary and Conclusion --- p.65 / Bibliography --- p.67

Direct Numerical Simulation of channel flow was utilized to study the evolution of various vortex configurations presented as flow initial conditions. Simulations of longitudinally, laterally and cross-flow oriented vortices suggested that the predominant form of turbulent structure was the half hairpin vortex. This vortical structure was dominant in the simulations seen in this as well as other investigations. In all cases hairpin vortices quickly degenerated to half hairpin or inclined vortical structures. It is hypothesized that these structures function as the predominant momentum transfer mechanism within the boundary layer, entraining fluid into the vortex cores like miniature tornados and transporting this fluid to the top of the boundary layer while simultaneously dragging fluid viscously around the inclined core of the vortex causing mixing of low-speed and high-speed flows.

Both neuroinflammation, and an increase in microglial cells, have been associated with Autism Spectrum Disorder (ASD) through observation in human subjects as well as in mouse models. A mother having an infection early in pregnancy increases the chances for autism in her child. (Atladottir et al., 2012). This process is known as Maternal Immune Activation (MIA), and the proposed mechanism is that inflammatory signals cross from the mother to child; then in response to increased pro-inflammatory cytokines, microglia within the brain are activated to combat the infection. Microglia are essential to healthy synaptogenesis and neuronal growth, and a change in their signaling early in development has been shown to alter behavior in mouse models that replicate MIA. We use microglial depletion as a therapy to counteract the potentially harmful pro-inflammatory response in the developing mouse brain. Four experimental groups - control, MIA, microglial depleted, and a therapy group (MIA plus microglial depletion)- were run through a comprehensive series of behavioral and electrophysiological assessments. Layer 5 pyramidal cells (L5PNs) were targeted for recording in medial frontal cortex – a mouse cortical area important for cognition and social behavior. L5PNs are a heterogeneous population with cortical and subcortical targeting. Subcortical targeting neurons are thick tufted morphologically, and have an intrinsically bursting spike pattern. Analysis of the intrinsically bursting neurons revealed significant differences between the maternal inflammation and the microglial depletion groups across multiple physiological properties. Therefore, the therapy group had electrophysiological characteristics more consistent with the microglial depleted model than the autism model.

Made available in DSpace on 2017-07-24T19:38:14Z (GMT). No. of bitstreams: 1 RAFAELA D OLIVEIRA.pdf: 2756499 bytes, checksum: e1e60d222b6dbe62066658f22ea4de0b (MD5) Previous issue date: 2014-08-22 / In this work, starch-stabilized silver nanoparticles (AgNPs-Am) were synthesized by reduction of AgNO3 using the NaBH4. The temperature and concentration of reagents of the synthesis were optimized. The formation of AgNPs-Am was monitored by UV-Vis spectroscopy and dynamic light scattering (DLS). The optimum conditions found for the AgNPs-Am synthesis were starch 0.6 % (w/v), 3.6 x 10-3 mol L-1 NaBH4, 0.9 x 10-3 mol L-1 AgNO3 and synthesis in bath ice. The average size of the AgNPs-Am was between 21 and 77 nm. Transmission electron microscopy (TEM) confirmed the AgNPs-Am formation inside and outside of the starch chains, however the smaller sizes were referred to the NPs stabilized by starch. Measurements of Potential zeta indicated stability of the particles, confirmed by DLS monitoring that demonstrated low agglomeration of NPs in a period of 115 days. For the characterization of AgNPs-Am it was also used infrared spectroscopic (FTIR) and X-ray diffraction (XRD). The AgNPs-Am were applied as polyanion for the construction of films by Layer-by-Layer technique (LbL), alternating with polycation 3-n-propylpyridinium-silsesquioxane (SiPy+Cl-). In order to obtain the films, pH and immersion time of the polyelectrolytes were optimized, as well as the concentration of SiPy+Cl-, monitoring the deposition by UV-Vis. The optimum parameters were immersion time 240 seconds, 2 mg/mL SiPy+Cl- pH 6.5 and AgNPs-Am pH 9.0. Atomic force microscopy (AFM) images showed that film thickness increases linearly and the roughness decrease with the bilayers number. FTIR spectra and Raman confirmed the interaction between the polyelectrolytes in the assembly of LbL films. The LbL films with architecture (SiPy+Cl-/AgNPs-Am)n (n = bilayers number) were applied as modified electrodes for iodine detection, using differential pulse voltammetry (DPV). It was verified that interaction of the components in the LbL films improved the current intensity. The film (SiPy+Cl-/AgNPs-Am)n (n=5) showed better current response in phosphate buffered saline (PBS) 0.1 mol L-1 pH 7.0. The instrumental parameters Epulse, and tpulse were optimized by 23 factorial design. It was verified a significant effect for third order interaction for the intensity of iodine redox peak currents, so the instrumentals parameters were evaluated together. The results of optimization were tpulse = 0.05 s, = 40 mV/s e Epulse = 50 mV. Accordingly, the modified electrode obtained a linear response for iodine concentrations ranging from 4.34 x 10-5 to 3.47 x 10-4 mol L-1 (R=0,9936) and from 4.40 x 10-4 to 4.24 x 10-3 mol L-1 (R=0,9938). It was obtained limit of detection (LOD) 5.56 x 10-6 and 1.51 x 10-5 mol L-1 and for limit of quantification (LOQ) 1.85 x 10-5 and 5.04 x 10-5 mol L-1, respectively. The AgNPs-Am synthesized in this work also acted as colorimetric sensor for iodine, with three regions of linearity. Two analytical curves were obtained for iodine concentration range from 2.40 x 10-7 to 9.50 x 10-7 mol L-1 and from 2.40 x 10-6 mol L-1 to 1.60 x 10-5 mol L-1. It was obtained a LOD of 1.71 x 10-8 and 1.06 x 10-6 mol L-1 and LOQ of 5.69 x 10-8 to 3.55 x 10-6 mol L-1, respectively for each range. Color variations obtained in these concentrations correspond to interaction between iodine and silver, which were monitored by UV-Vis band showed in 410 nm. At concentrations above 5.50 x 10-5 mol L-1 there is the appearance of blue color, absorbance in 600 nm, corresponding to the interaction between starch and iodine. It was also obtained a linear relationship for iodine concentration from 5.50 x 10-5 mol L-1 to 9.50 x 10-5 mol L-1. For this concentration range, LOD and LOQ were respectively 1.37 x 10-6 and 4.58 x 10-6 mol L-1. The results presented confirm the potential use of AgNPs-Am for iodine detection, both for the modification of electrodes for electrochemical determination as a colorimetric sensor. / Neste trabalho foram sintetizadas nanopartículas de prata estabilizadas em amido (AgNPs-Am). A síntese foi realizada por redução do sal AgNO3 utilizando o NaBH4. A temperatura de síntese e concentração dos reagentes foram otimizadas, a formação das AgNPs-Am foi monitorada por espectroscopia na região do UV-Vis e medidas de espalhamento dinâmico da luz (DLS). As condições ótimas encontradas para síntese de AgNPs-Am foram amido 0,6 % (m/v), 3,6.10-3 mol.L-1 de NaBH4, 0,9.10-3 mol.L-1 de AgNO3 e síntese em banho de gelo. O tamanho médio das AgNPs-Am foi entre 21 e 77 nm. Imagens de microscopia eletrônica de transmissão (TEM) confirmaram que houve formação das AgNPs no interior e fora das cadeias de amido, sendo os menores tamanhos referentes às NPs estabilizadas pelo amido. Medidas de Potencial zeta indicaram estabilidade das NPs, confirmada por acompanhamento DLS que demonstrou baixa aglomeração em um período de 115 dias. Para caracterização das AgNPs-Am utilizou-se também espectroscopia na região do infravermelho (FTIR) e difração de raios X (XRD). As AgNPs-Am foram utilizadas como poliânion para construção de filmes pela técnica Layer-by-Layer (LbL), alternando com policátion 3-n-propilpiridínio-silsesquioxano (SiPy+Cl-). Para construção dos filmes, pH e tempo de imersão dos polieletrólitos foram otimizados, assim como concentração de SiPy+Cl-, monitorando a deposição por UV-Vis. Os parâmetros ótimos foram tempo de imersão 240 segundos, solução de 2 mg/mL de SiPy+Cl- pH 6,5 e AgNPs-Am pH 9,0. Imagens de microscopia de força atômica (AFM) mostram que a espessura dos filmes aumenta linearmente e a rugosidade decresce com o número de bicamadas. Espectros FTIR e Raman confirmaram a interação entre os polieletrólitos na montagem dos filmes. Os filmes LbL com configuração (SiPy+Cl-/AgNPs-Am)n (n = número de bicamadas) foram aplicados como eletrodos modificados para detecção de iodo, utilizando-se voltametria de pulso diferencial (VPD). Verificou-se que a interação dos componentes no filme LbL melhorou a intensidade de corrente. O filme (SiPy+Cl-/AgNPs-Am)n (n=5) apresentou melhor resposta de corrente em eletrólito suporte tampão fosfato salino (PBS) 0,1 mol.L-1 pH 7,0. Os parâmetros instrumentais Epulso, e tpulso foram otimizados por planejamento fatorial 23. Verificou-se efeito significativo para interação de terceira ordem para intensidade de corrente do pico de redução do iodo, portanto os parâmetros instrumentais foram avaliados em conjunto. Os resultados da otimização foram tpulso = 0,05 s, = 40 mV/s e Epulso = 50 mV. Nestas condições, o eletrodo modificado obteve resposta linear para concentrações de iodo que variam de 4,34.10-5 a 3,47.10-4 mol.L-1 (R=0,9936) e de 4,40.10-4 a 4,24.10-3 mol.L-1 (R=0,9938). Respectivamente, obteve-se limite de detecção 5,56.10-6 e 1,51.10-5 mol.L-1 e para o limite de quantificação 1,85.10-5 e 5,04.10-5 mol.L-1. As AgNPs-Am sintetizadas neste trabalho também atuaram como sensor colorimétrico de iodo, com três regiões de linearidade. Duas curvas analíticas foram construídas para concentrações de iodo de 2,40.10-7 a 9,50.10-7 mol.L-1 e de 2,40.10-6 mol.L-1 a 1,60.10-5 mol.L-1. Obteve-se LD de 1,71.10-8 e 1,06.10-6 mol.L-1 e LQ de 5,69.10-8 e 3,55.10-6 mol.L-1, respectivamente para cada intervalo. As variações de cores obtidas nestas concentrações correspondem a interação entre o iodo e a prata, as quais foram acompanhadas pela banda UV-Vis apresentada em 410 nm. Em concentrações acima de 5,50.10-5 mol.L-1 observa-se o aparecimento de coloração azul, absorbância em 600 nm, correspondente a interação entre amido e iodo. Obteve-se linearidade para concentrações de 5,50.10-5 mol.L-1 a 9,50.10-5 mol.L-1. Para este intervalo de concentração, os LD e LQ são respectivamente 1,37.10-6 e 4,58.10-6 mol.L-1. Os resultados apresentados confirmam a potencialidade do uso das AgNPs-Am para detecção de iodo, tanto na modificação de eletrodos para determinação eletroquímica, quanto o uso como sensor colorimétrico.

Submitted by Angela Maria de Oliveira (amolivei@uepg.br) on 2018-02-07T12:42:14Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Rolf de Campos.pdf: 5588727 bytes, checksum: d81ab37d8cd335285d51711794fbbc44 (MD5) / Made available in DSpace on 2018-02-07T12:42:14Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Rolf de Campos.pdf: 5588727 bytes, checksum: d81ab37d8cd335285d51711794fbbc44 (MD5) Previous issue date: 2017-07-05 / Fundação Araucária de Apoio ao Desenvolvimento Científico e Tecnológico do Paraná / Esta tese descreve as interações entre o surfactante não iônico p-(1,1,3,3 tetrametilbutil) fenil polietilenoglicol (denominado Triton X) e dodecil sulfato de sódio (SDS) com o polímero catiônico 3-cloreto-n-propilpiridínio silsesquioxano (SiPy) na presença da ftalocianina tetrasulfonada de níquel (NiTsPc), as quais foram avaliadas utilizando medidas de tensão superficial e viscosidade. Os efeitos dessas interações também foram estudados quando estes polieletrólitos foram transferidos para filmes finos pela técnica LbL sobre substrato condutor (óxido de estanho dopado com índio – ITO), quartzo e silício. Observou-se, por meio de técnica espectroscópica de absorção na região do UVVis, que há um efeito sinérgico proporcionado pela interação dos polieletrólitos catiônico (SiPy/surfactante) e aniônico (NiTsPc) nos filmes LbL. Por técnicas espectroscópicas FTIR e Raman, e técnicas eletroquímicas tais como impedância eletroquímica e voltametria cíclica, foi constatado que há coexistência de micelas mistas e puras e que a adsorção destes agregados tem um papel importante na superfície dos filmes LbL. Foi também realizada a síntese e a caracterização de nanopartículas de hidróxido de níquel, em sua fase α, estabilizadas pelo polímero SiPy, e pelo surfactante zwiteriônico 3-(1- alquil-3-imidazólio)propano-sulfonado. O surfactante ImS3-14 foi escolhido por sua interação preferencial com ânions, tornando-o um excelente limitante para o crescimento das nanopartículas de Ni(OH)2. A formação dos agregados foi caracterizada por espalhamento dinâmico de luz e potencial zeta, para determinar tamanho e carga das nanopartículas, respectivamente. Após a síntese das nanopartículas, estas foram depositadas através da técnica LbL em vários substratos. O crescimento dos filmes foi acompanhado por UV-VIS e sua caracterização foi realizada pelas técnicas de FTIR, Raman, AFM e MEV-FEG. As características eletroquímicas dos filmes foram estudadas por voltametria cíclica (VC) e espectroscopia de impedância eletroquímica (EIE). / This thesis describes the interactions between the nonionic surfactant p-(1,1,3,3- tetramethylbutyl)phenyl-polyethylene glycol (Triton X) and sodium dodecyl sulfate (SDS) with the cationic polymer 3-chloride-n-propylpyridinium silsesquioxane (SiPy) in the presence of nickel phthalocyanine tetrasulfonate (NiTsPc), which they were evaluated using surface tension and viscosity measurements. The effects of these interactions were also studied when these polyelectrolytes were transferred to thin films by the LbL technique on conductive substrate (indium doped tin oxide - ITO), quartz and silicon. It has been observed by UV-Vis absorption spectroscopy there is a synergistic effect provided by the interaction of the cationic polyelectrolytes (SiPy / surfactant) and anionic (NiTsPc) polyelectrolytes in the LbL films. Spectroscopic techniques, such as, FTIR and Raman, and electrochemical techniques, electrochemical impedance and cyclic voltammetry, it was observed that there is a coexistence of mixed and pure micelles. The adsorption of these aggregates plays an important role on the surface of the LbL films. The synthesis and characterization of nickel hydroxide nanoparticles, in their α phase, stabilized by the SiPy polymer, and by the zwitterionic surfactant 3- (1-alkyl-3 - imidazolium) propane sulfonate was realized. The surfactant ImS3-14 was chosen for its preferential interaction with anions, making it an excellent stabilizer for the growth of the Ni(OH)2 nanoparticles. The formation of the aggregates was characterized by dynamic scattering of light (DLS) and zeta potential to determine size and charge, respectively. After the synthesis of the nanoparticles, they were deposited by the LbL technique on several substrates. The growth of the films was accompanied by UV-VIS and their characterization was evaluated by FTIR, Raman, AFM and MEV-FEG techniques. The electrochemical characteristics of the films were studied using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS).

Thesis (Sc.D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Vita. / Includes bibliographical references. / by Frank Glenroy Smith, III. / Sc.D.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by Lawrence M. Hull. / Ph.D.

<div>The dynamic performance of the momentum and thermal boundary layer linked to the acoustic response dictate the efficiency of heat exchangers and the operational limits of fluid machinery. The specific time required by the boundary layer to establish or adapt to the free stream variations is vital to optimize flow control strategies as well as the thermal management of fluid systems. The proper understanding of the wall fluxes, separated flow regions and free stream response to transient conditions becomes the fulcrum of the further improvement of fluid machinery performance and endurance. Throughout this dissertation the establishment sequence and the main parameters dictating the acoustic response and the boundary layer settlement are quantified together with their implication on the wall fluxes and boundary layer detachment. </div><div><br></div><div>Unsteady Reynolds Average Navier Stokes evaluations, Large Eddy Simulations, Direct Numerical Simulations and wind tunnel experiments are exploited to analyze the transient behavior of attached and detached flow aerodynamics. The core of the research is built upon URANS simulations allowing the realization of multiple detailed parametric analyses. Thanks to its reduced computational cost, hundreds of transient flow evaluations are carried out, enabling the determination of the establishment sequence, the main flow features and relevant non-dimensional numbers. The URANS methodology is verified against experimental and analytic results on the flow conditions of the study. The Large Eddy Simulations and Direct Numerical Simulations allow further characterization of the near wall flow region behavior with much higher resolution while providing an additional source of verification for the coarser numerical tools. An experimental campaign on a novel full visual access linear wind tunnel explores the impact of mean flow sudden accelerations on the boundary layer detachment and reattachment phenomena over an ad-hoc wall mounted hump. The wind tunnel is designed based on the premises of: full visual access, spatial and temporal stability of total and static pressure together with the total temperature and fast flow settlement, minimizing the start-up phase duration of the wind tunnel. A wall mounted hump that mimics the behavior of the aft portion of a low pressure turbine is inserted in the wind tunnel guaranteeing a 2D flow separation phenomena. After steady state test article characterization series of sudden flow discharge experiments reveal the impact of mean flow transients on the boundary layer detachment inception. Finally, taking advantage of the knowledge on transient flow performance, optimum flow control mechanisms to abate boundary layer detachment are proposed. The recommended control approach effectively prevents the boundary layer separation while minimizing the energy requirement.</div>

This work seeks to apply the novel heat flux sensor called as the Atomic Layer Thermopile to measure high frequency heat flux in high speed and high temperature flows found in Gas Turbine combustors. To achieve this the sensor must be able to survive the harsh environment of high temperature and high pressure. To have any confidence in our measurement, it is also imperative that there are tools available for precise estimation of the measurement uncertainty. This works strives to achieve these objectives by developing calibration techniques for uncertainty estimation using both exposure to radiation and in convective environments by calibrating against power input in steady state flow and transient heat flux calculated using wall temperature measurement. The response of the sensor is then investigated in high speed flows by measuring the heat flux inside a supersonic nozzle when exposed to shock waves. The shock waves are generated using a fast throttle valve located at the entrance of the supersonic nozzle by generating sudden rise in pressure. Lastly a numerical study is carried out to design a cooling system that will allow the sensor to survive in high temperature conditions of 1000°C while the sensor film is maintained at 50°C. A one-dimensional model is used to provide initial design parameters and then a two-dimensional axisymmetric conjugate CFD analysis is carried out to obtain the desired geometry that can meet the design conditions. A static structural analysis is also carried out on this geometry to ensure that it will be able to survive and avoid distortion under the operational pressure required for providing the desired coolant mass flow.