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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Two phase mixing comparison, oil contamination comparison and manufacturing accuracy effect on calibration of slotted orifice meter

Sparks, Sara A. 15 November 2004 (has links)
In previous studies the slotted orifice plate has demonstrated superior performance characteristics to those of the standard orifice plate. In this study, these comparisons are investigated further. The response characteristics of the slotted orifice plate to the standard orifice plate and V-Cone for two-phase flows of water and air at various qualities, flow rates, and pressures are shown visually. The effect of oil as it flows through a slotted orifice plate and standard orifice plate are visually documented. The effect of manufacturing accuracy on the slotted orifice plates is investigated as to the effect on the coefficient of discharge, percent change in pressure, and Reynolds number. The slotted orifice plate mixes two-phase flow better than the standard orifice plate and V-Cone. There is a manufacturing effect on the slotted orifice plates; the larger the area of the slots, the larger the discharge coefficient.
2

Two phase mixing comparison, oil contamination comparison and manufacturing accuracy effect on calibration of slotted orifice meters

Sparks, Sara A. 15 November 2004 (has links)
In previous studies the slotted orifice plate has demonstrated superior performance characteristics to those of the standard orifice plate. In this study, these comparisons are investigated further. The response characteristics of the slotted orifice plate to the standard orifice plate and V-Cone for two-phase flows of water and air at various qualities, flow rates, and pressures are shown visually. The effect of oil as it flows through a slotted orifice plate and standard orifice plate are visually documented. The effect of manufacturing accuracy on the slotted orifice plates is investigated as to the effect on the coefficient of discharge, percent change in pressure, and Reynolds number. The slotted orifice plate mixes two-phase flow better than the standard orifice plate and V-Cone. There is a manufacturing effect on the slotted orifice plates; the larger the area of the slots, the larger the discharge coefficient.
3

Wave propagation, phase mixing and dissipation in Hall MHD

Threlfall, James W. January 2012 (has links)
In this thesis the effect of the Hall term in the generalised Ohm's law on Alfvén (shear) and fast wave propagation and dissipation in the ion cyclotron frequency range is investigated. The damping of an initially Gaussian field perturbation in a uniform Hall MHD plasma is treated analytically. Subsequently a 2D Lagrangian remap code (Lare2d) is used to study the damping and phase mixing of initially Gaussian field perturbations and a harmonic series of boundary-driven perturbations in a uniform field (in the presence of a transverse equilibrium density gradient). The same code is then used to study a range of initially shear and fast-wave perturbations in the vicinity of a magnetic X-type null point. The magnetic energy associated with an initially Gaussian field perturbation in a uniform resistive plasma is shown to decay algebraically at a rate that is unaffected by the Hall term to leading order in kδ where k is wavenumber and δ is ion skin depth. A similar decay law applies to whistler perturbations in the limit kδ>>>1. We demonstrate that in both geometries considered, the inclusion of the Hall term reduces the effectiveness of phase-mixing in plasma heating. The reduction in the damping rate in the uniform field (non-uniform density) cases, arising from dispersive effects, tends to zero in both the weak and strong phase mixing limits. In the Hall MHD X-point case, minimal reductions are seen for initially shear wave pulses, suggesting that little or no phase-mixing takes place. Nonlinear fast wave pulses which interact with the initial X-point destabilise the local field sufficiently to generate multiple null pairs; subsequent oscillatory current sheet behaviour appears unaffected by earlier differences between the MHD and Hall MHD cases.
4

Design and Fabrication of Piezoresistive Flexible Sensors based on Graphene/ Polyvinylidene Fluoride (PVDF) Nanocomposite

Maharjan, Surendra 15 September 2022 (has links)
No description available.
5

A Multi-Wilkinson Power Divider Based Complex Reflection Coefficient Detector

Cooper, James Roger 19 May 2010 (has links)
In the field of applied electromagnetics, there is always a need to create new methods for electrical characterization of materials, systems, devices, etc. Many applications need small and/or inexpensive equipment in performing these characterizations. The current method for making measurements of electrical properties at frequencies above 300 MHz, the transmission/reflection method, has severe limitations in these areas due large size and high price of the necessary equipment for making them. Therefore, presented herein is the conceptualization, design and analysis of a complex reflection coefficient detector which is relatively small, lightweight, and inexpensive. A reflection coefficient detector is a device designed to isolate and compare a driving signal against a reflected signal. The reflection of the second signal is caused by a mismatch between the device's output impedance and a load's input impedance. By comparing the driving, or transmitted, signal and the reflected signal, the reflection coefficient at the boundary can be calculated. This coefficient can be used to calculate a load's input impedance, or a material's permittivity when combined with an attached probe's characteristics. The reflection coefficient detector presented is built using microstrip and surface mount components. This makes the device comparably cheap. Its design is based upon five Wilkinson Power Dividers which lends itself to be scaled down for implementation in on-chip, and other micro- and nano- scale systems. The accuracy and functionality of the device will be demonstrated through the use of S-Parameters measurements and CAD simulations. Through this, it will be shown that the device is a practical form of making measurements in applications which are otherwise restricted to certain limitations. In closing, applications, alternative designs and future advancements of the complex reflection coefficient detector will be discussed.

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