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 327 for “"flow velocity"”.
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The measurement of flow velocity distribution
… and accuracy achieved by the cross-correlation flowmeter is investigated. The principles of the flowmeter operation and fundamental digital signal processing techniques are reviewed. The process of the Fourier transform deconvolution is investigated. Computer simulation of the flow system is …
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Critical flow velocity in super fluid 3He-B
… in uniform linear motion at the Landau critical velocity. The experiments were performed in a “Lancaster style” nested experimental cell at ultra-low temperatures within the ballistic limit. In the first set of experiments we studied two almost identical quartz tuning fork resonators with …
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Flow velocity measurement in haemodialysis access using 4D MRI
… computer modelling techniques and computational flow dynamics. Previously, the required imaging was provided by contrasted MRI, contraindicated in renal failure. Haemodynamic data was prvided by, amongst other things, duplex Doppler. New MRI software that provides imaging data as well as …
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Effect of head elevation on intracranial blood flow velocity following acute ischemic stroke
… elevation on middle cerebral artery (MCA) mean flow velocity (MFV) in a convenience sample of 20 patients presenting with acute ischemic stroke. Transcranial Doppler (TCD) sonography mounted by head frame was used to measure MCA MFV. Patients were on average 59.5 years of age (SD = 15.4), with a …
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A flume study of bed forms in a medium sand as a function of flow velocity
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1991.
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The use of a neural network to recognize placental insufficiency from blood flow velocity waveforms in the umbilical cord
… based on measuring the umbilical arterial blood flow velocity waveforms from one site of the cord. There is an ongoing debate on the predictive value of Doppler measurements in the evaluation of the foetal condition. The aim of this thesis is to investigate the use ofa neural network to recognise …
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Plant-habitat interactions in brackish marshes
… By buffering a large part of the arriving flow velocity, attenuating wave energy and serving as erosion control for riverbanks, tidal marshes furthermore reduce the destructive effects of storm surges and storm waves and thus contribute to ecosystem-based shore protection. However, in many …
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Nonlinear Estimation and Control Methods for Mechanical and Aerospace Systems under Actuator Uncertainty
<p>Air flow velocity field control is of crucial importance in aerospace applications to prevent the potentially destabilizing effects of phenomena such as cavity ow oscillations, flow separation, flow-induced limit cycle oscillations (LCO) (flutter), vorticity, and acoustic instabilities. Flow …
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Doppler ultrasound technique used to determine the blood flow viscosity in the middle cerebral artery of a canine animal model
The cerebral blood flow velocity in the middle cerebral artery of an canine animal model was measured using the Doppler Ultrasound technique. A transducer was designed with a 20 MHz piezoelectric crystal and used for the application. An in vitro calibration system was designed and machined for the …
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Quantification of Velocity at the Sparkplug in a Lab Scale Combustion Chamber
… understand the turbulence characteristics of the flow in the optical chamber. Spark anemometry was used to obtain a relationship between the spark plasma evolution and freestream velocity. Finally, this technique has been applied to the turbulent flow inside the combustion chamber to determine the …
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Advanced Ignition Strategies for Future Internal Combustion Engines with Lean and Diluted Fuel-Air Mixtures
… or diluted fuel-air mixtures under enhanced gas flow conditions for applications in future internal combustion engines. Various spark ignition strategies were deployed by controlling the spark discharge process via different spark ignition hardware configurations. Modulated spark discharge …
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Image Analysis of Air-bubble Injection (Front and Side View) into a Turbulent Liquid Stream
… views were used: a front view in which flow velocity was 0.80 m/s (2.68 GPM) at Reynolds number, Re=7413 and to inject air bubbles into water stream air bubble injection rate was set at 0.046 m/s (350 μl/min), as well as the side view in which all the conditions were the same except the …
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Solute Transport and Biodegradation Characteristics for Models of Enhanced Subsurface Bioremediation
… that is enhanced by the retarded substrate velocity and localized nonlinear biodegradation that is limited to the mixing zone. The balanced interaction between these two processes causes the solute concentration fronts to travel downstream in unison (front coherence) and promotes the …
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Design and optimization of an MHD energy harvester for intelligent pipe systems
… conductivity of water, magnetic flux density B, flow velocity u and the channel volume to the power output is first established. This leads to the decoupled analysis and simulations of magnetic field and flow field. The prototyped energy harvester without the concentrator achieves a power output …
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Resposta dinâmica e estabilidade de tubos com escoamento interno
… quotient is used to study the influence of flow velocity on the eigenvalues behaviour, and theoretical estimates for the stability of the equilibrium position are obtained. It is shown that, for a periodic flow velocity, parametric resonance occurs and the boundaries of these instability …
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The effects of geometrical changes on airflow of developing-world solar fruit dryers
… dryers with small fans to induce active air flow, which enhances drying capabilities. This thesis examines the effects of changes in dryer geometry on the air flow within flatbed solar dryers. The interior of a dryer was simulated using Ansys Fluent, and air flow velocity and patterns were …
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