Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 58 for “"Backflow"”.
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Backflow and pairing wave function for quantum Monte Carlo methods
… wave functions for QMC. An extension of the backflow transformation to inhomogeneous electronic systems is presented and applied to atoms, molecules and extended systems. The backflow transformation I have developed typically retrieves an additional 50% of the remaining correlation energy at …
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Numerical simulation of ion thruster plume backflow for spacecraft contamination assessment
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1995.
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Thermal performance of backflow solar air heating with integrated nanoparticle enhanced pcm absorber storage system
The present study has been executed to clarify the advantage of using latent thermal storage integrated with a back pass solar air heater (SAH). The purpose of this study is to design, fabricate and evaluate the performance of SAH with integrated nanoparticles enhanced phase change material (PCM) …
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Prediction and mitigation strategies for the transient thermal performance of low thermal resistance microchannel evaporators
… revealed the presence of severe vapor backflow, large temperature overshoots, and impacted flow dynamics at the onset of nucleate boiling (ONB) despite the stability and high performance of the device under steady state heating conditions. These overshoots were exacerbated with higher …
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A quantum Monte Carlo study of the two-dimensional electron gas
… a system of many fermions. With introduction of backflow and three-body correlations, we find significant improvements in both variational and fixed-node energies over the Slater-Jastrow results which consider only two-body correlations. It is found that the backflow effect is dominant over the …
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Improved wave functions for quantum Monte Carlo
… VMC and DMC levels. Similar generalizations to backflow transformations will allow useful additional variational freedom in the wave function. In particular, the use of different backflow functions for different orbitals is expected to be important in systems where the orbitals are qualitatively …
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Role of tip clearance flow on axial compressor stability
… behavior are proposed based on trailing edge backflow and leading edge spillage to the adjacent blade passage. Both are associated with tip clearance flow and occur below the blade tip. Trailing edge backflow involves tip clearance fluid from adjacent blade passages. The leading edge spillage …
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The effect of spark timing on residual gas fraction
… modeled as the sum of two contributing factors: backflow from the exhaust port to the cylinder during valve overlap and gas trapped inside the cylinder at the time of intake valve open. Additionally, the phenomenon of choked backflow was introduced in the model. Based on the data, a correlation …
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Modelling of satellite control thruster plumes
… was also used to calculate the nozzle lip and backflow expansion regions of the same hydrazine thruster. A significant degree of backflow was found with flow angles of up to 140º. The sensitivity of the calculations to the conditions initially assumed were assessed and found to be important.
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CHAOS: A multi-GPU PIC-DSMC solver for modeling gas and plasma flows
… plume and the thruster surface, resulting in a backflow of ions towards the critical solar panel and thruster surfaces. Three backflow quantities, namely, ion flux, incidence angle, and incidence energy affect the macroscopic sputtering rate of the solar panel surfaces over extended operational …
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Optically induced orientational transitions in nematic liquid crystals
… velocity field induced by the director motion (backflow) has been neglected. In Chapter 4 I have investigated the influence of backflow on the dynamical scenario described in Chapter 2 and have shown that the backflow leads to substantial quantitative changes. It turns out that the regime of …
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Instruments design and testing for a Hall thruster plume experiment on the space shuttle
… to obtain in-space measurements in the plume and backflow regions of lowpower thrusters. The ETEEV payload will be installed on a Hitchhiker-palette onboard the Shuttle and will use plasma diagnostics mounted on the palette as well as on an articulated boom. Other objectives include contamination …
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Studies Of Liquid Crystal Response Time
… An important effect related to response time, backflow is analyzed using a homogeneous LC cell in an infrared wavelength. The Leslie viscosity coefficients can hardly be found in the literature. A new effective approach to estimate the Leslie coefficients of LC mixtures based on MBBA data is …
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Topics in low temperature Fermi liquid theory
… two extreme models for the momentum dependent backflow potential. The transport properties are calculated and found to be two to three orders of magnitude larger than those of the unpolarized liquid at the same density. The elementary excitation spectrum is found to be quite sensitive to the …
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Measurements in the bimodal region of a wing-body junction flow with a rapidly-scanning two-velocity-component laser-Doppler velocimeter
… vortex is concentrated near the nose, with large backflow, when the surface pressure signal is above the mean. The junction vortex is larger, with smaller backflow near the nose, when the surface pressure signal is below the mean. The velocity-pressure cross-correlations and space-time …
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Sturcture of Three-Dimensional Separated Flow on Symmetric Bumps
… Downstream of the saddle point the mean backflow converges to the focal separation points in a thin region confined within about 0.15delta from the local bump surface. The mean backflow zone is supplied by the intermittent large eddies as well as by the near surface flow from the side of …
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Physics Based Modeling and Characterization of Filament Extrusion Additive Manufacturing
… and the nozzle wall, referred to as annular backflow. The study presented in this dissertation explores this phenomenon, determining its cause and sensitivity to processing parameters and material properties. A dimensionless number, named the "Flow Identification Number" or FIN, is defined …
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Development, testing, and evaluation of the central-flow, double- leaflet heart valve
… compared to other prostheses. In addition, the backflow and mean leak associated with the new valve were too high. Details of the testing procedures are presented and recommendations for future valve modifications and testing are included.
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Experimental investigation of the flow field in a missile launch tube
… patterns in the baseline configuration, such as backflow, jetting, and recirculation regions, as well as for the location of several potential hot spots. The mixing of the fuel-rich gas generator effulent and the air in the launch tube was assessed by thermocouple measurements; warm water was …
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Microscopic study of salt precipitation dynamics during the injection process of CO2 storage in saline aquifers
… risk. Brine migration, driven by capillary backflow, intensifies localized precipitation. Ex-situ precipitation, caused by mobile bulk crystals moving away through residual brine, worsens pore blockage. Salt precipitation dynamics are quantified in three stages: 1) the nucleation stage, …
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