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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.
11

Hydrologic behaviour and hydraulic properties of a patterned fen in Saskatchewan

Hogan, Jaime Michele 30 January 2006 (has links)
A patterned, partially-treed, fen in the mid-boreal region of central Saskatchewan was the site of renewed hydrological research from 2002 to 2004. Hydraulic conductivity, transmissivity, and storativity were determined through use of a surface loading test, pumping tests, and an enclosed field drainage test. None of these field tests have been previously described in the literature as having been used in peat environments. The combined results of field and laboratory drainage tests were used to obtain a general storativity with water table depth relationship in the upper peat layer. The hydraulic conductivity, measured with slug tests, the loading test, and pumping tests, is high near the surface, declining greatly with depth. These previously untested field methods have the advantage of representing volumes of peat from tenths of a meter to cubic meters. </p>Characterization of the hydrology of the peatland involved year round observations of water table, piezometric head, peat surface elevations, frost depth and peat temperatures. Fluctuations of the water table, and soil moisture changes produce changes in effective stress that lead to volume change in the highly compressible peat. This is particularly important for sites with thick peat deposits. Independent compressibility estimates were as high as 10-5 N/m2 in the upper peat. At three fen sites, changes in peat thickness were estimated from monthly estimates of effective stress change, using year round hydrological observations, and compared to measured annual peat thickness changes. Water table changes causing soil moisture changes, and freeze-thaw processes, explained the majority of peat surface movements.
12

Research and Applications of the Transmission Performance of Coupler-Driven Mechanisms with Sliders

Wang, Chun-yuan 13 July 2004 (has links)
This research uses Transmissivity Index (TI) and other transmission indices to analyze the transmission performance by applying those indices to coupler-driven mechanisms with sliders. Other estimative transmission indices include Total Transmission Index (TTI) and Transmissible Mechanical Advantage (TMA). The point with best transmission performance is ¡§Effective Point,¡¨ and the combination of the effective points becomes ¡§Locus of Effective Points¡¨. In addition, this research puts the influence of mechanisms with sliders including slider-friction into consideration, and also analyzes two inverses of mechanisms with sliders. Then we can extend to study the transmission performance of six-bar mechanisms. Finally, we apply the research result into some examples, such as ping pong table mechanism, four-bar and six-bar windows operator mechanisms, rowing exercise mechanism, so that we can find the better transmission performance of those mechanisms.
13

Application of fluid electrical conductivity logging for fractured rock aquifer characterisation at the University of the Western Cape's Franschhoek and Rawsonville research sites

Lasher, Candice January 2011 (has links)
<p>&nbsp / Characterisation of fractured rock aquifers is important when dealing with groundwater protection and management. Fractures are often good conduits for water and contaminants, leading to high flow velocities and the fast spread of contaminants in these aquifers. A cost effective methodology is required for the characterisation of the role of individual fractures contributing to flow to boreholes in fractured rock aquifers. Literature shows that some of the conventional methods used to characterise hydraulic properties in fractured rock aquifers are expensive, complicated, time consuming and are associated with some disadvantages such as over-or under- estimations of flow rates. iii This thesis evaluates the use of Fluid Electrical Conductivity (FEC) logging in fractured rock aquifers. This FEC data are compared to various traditional methods used to determine aquifer hydraulic properties applied at the Franschhoek and Rawsonville research sites. Both these sites were drilled into the fractured rock Table Mountain Group (TMG) Aquifer, forming one of the major aquifers in South Africa.</p>
14

Transmissividade de Spins Polarizados em dupla barreira simétrica

Marques, Efraim Fernandes 02 October 2012 (has links)
Submitted by Geyciane Santos (geyciane_thamires@hotmail.com) on 2015-08-06T15:41:08Z No. of bitstreams: 1 Dissertação - Efraim Fernandes Marques.PDF: 1576792 bytes, checksum: 9f5d857f0e1015473fb55bdbd1206731 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-08-07T13:48:53Z (GMT) No. of bitstreams: 1 Dissertação - Efraim Fernandes Marques.PDF: 1576792 bytes, checksum: 9f5d857f0e1015473fb55bdbd1206731 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-08-07T13:50:56Z (GMT) No. of bitstreams: 1 Dissertação - Efraim Fernandes Marques.PDF: 1576792 bytes, checksum: 9f5d857f0e1015473fb55bdbd1206731 (MD5) / Made available in DSpace on 2015-08-07T13:50:56Z (GMT). No. of bitstreams: 1 Dissertação - Efraim Fernandes Marques.PDF: 1576792 bytes, checksum: 9f5d857f0e1015473fb55bdbd1206731 (MD5) Previous issue date: 2012-10-02 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In this dissertation, the scattering matrix technique is used to calculate the transmissivity of polarized spins through semiconductors heterostructures of symmetrical double barrier. The movement of electrons is described in the effective mass approach of the complete Dresselhaus models. The transmissivity and polarization are calculated as a function of electron energy with kjj = 0; 5x106cm􀀀1, kjj = 1x106cm􀀀1 and kjj = 2x106cm􀀀1 varying the angle GaSb=GaxAl1􀀀xSb=GaSb=GaxAl1􀀀xSb=GaSb system. Fixing the parallel moment kjj and varying = 30o, 45o, 60o and 90o, we observed that the positions of the resonant picks vary faintly with the energy and the transmission curves change more strongly in the areas out of the resonance, with the polarization reaching values among 54%􀀀!82% in the resonant levels. For the direction = 45o, the spin mixing produces a spin polarization efficiency of nearly 100 %. Applying an external voltage, the peak transmissivity and spin polarization undergo a shift towards regions to lower energies. / Neste trabalho, a técnica da matriz de espalhamento é usada para calcular a transmissividade de spins polarizados através de heteroestruturas semicondutoras de dupla barreira simétrica. O movimento de elétrons de condução são descritos na aproximação da massa efetiva do modelo completo de Dresselhaus. A transmissividade e a polarização são calculadas como função da energia do elétron para kjj = 0; 5x106cm􀀀1, kjj = 1x106cm􀀀1 e kjj = 2x106cm􀀀1 com vários valores de , para um sistema GaSb=GaxAl1􀀀xSb=GaSb=GaxAl1􀀀xSb=GaSb. Fixando o momento paralelo kjj e variando = 30o, 45o, 60o e 90o, observamos que as posições dos picos ressonantes variam fracamente com a energia e as curvas de transmissão mudam mais fortemente nas regiões fora da ressonância, com a polarização atingindo valores entre 54%􀀀!82% nos níveis ressonantes. Para a direção = 45o, o spin-mixing produz uma eficiência de polarização de quase 100%. Ao aplicarmos uma tensão externa, os picos de transmissividade e spin polarização sofrem um desclocamento para regiões de energias mais baixas.
15

Application of fluid electrical conductivity logging for fractured rock aquifer characterisation at the University of the Western Cape's Franschhoek and Rawsonville research sites

Lasher, Candice January 2011 (has links)
Magister Scientiae - MSc / Characterisation of fractured rock aquifers is important when dealing with groundwater protection and management. Fractures are often good conduits for water and contaminants, leading to high flow velocities and the fast spread of contaminants in these aquifers. A cost effective methodology is required for the characterisation of the role of individual fractures contributing to flow to boreholes in fractured rock aquifers. Literature shows that some of the conventional methods used to characterise hydraulic properties in fractured rock aquifers are expensive, complicated, time consuming and are associated with some disadvantages such as over-or under- estimations of flow rates. This thesis evaluates the use of Fluid Electrical Conductivity (FEC) logging in fractured rock aquifers. This FEC data are compared to various traditional methods used to determine aquifer hydraulic properties applied at the Franschhoek and Rawsonville research sites. Both these sites were drilled into the fractured rock Table Mountain Group (TMG) Aquifer, forming one of the major aquifers in South Africa. / South Africa
16

Propriedades termo-eletr?nicas da mol?cula do DNA

Moreira, Darlan Ara?jo 29 September 2008 (has links)
Made available in DSpace on 2015-03-03T15:16:23Z (GMT). No. of bitstreams: 1 DarlanAM.pdf: 1538525 bytes, checksum: af051bdcc4894d0bf236b2e6f943baa9 (MD5) Previous issue date: 2008-09-29 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Esta tese apresenta um abrangente e atualizado estudo de algumas propriedades f?sicas da mol?cula do DNA, tais como seus aspectos termodin?micos (calor espec?fico) e eletr?nicos (transmissividade eletr?nica, fator de localiza??o, entre outros). A mol?cula do DNA pode ser considerada uma seq??ncia simb?lica de quatro letras: guanina (G), adenina (A), citosina (C) e timina (T). Ela ? usualmente descrita como uma cadeia bidimensional aleat?ria com correla??o de curto-alcance, mas n?o h? impedimentos para que a cadeia seja crescida seguindo seq??ncias quasi-peri?dicas, como por exemplo, as sequ?ncias de Fibonacci e Rudin-Shapiro. Com o intuito de investigar a relev?ncia das correla??es subjacentes nas distribui??oes dos nucleot?deos, comparamos os resultados para a sequ?ncia gen?mica do DNA (Ch22) com as duas seq??ncias artificiais citadas acima, que possuem correla??ao de longo alcance. A an?lise do calor espec?fico ? feita considerando-se formalismos apropriados; o cl?ssico, utilizando a distribui??o de Maxwell-Boltzmann; a descri??oo qu?ntica, utilizando a distribui??o de Fermi-Dirac; e o formalismo da n?o-extensividade, usando a entropia de Tsallis. Os espectros de energias s?o calculados utilizando-se a equa??o de Schrodinger unidimensional na aproxima??o de liga??o forte. N?s calculamos tamb?m a transmissividade eletr?nica, o comprimento de localiza??o, bem como I (corrente) vs V (potencial), curva que caracteriza as propriedades el?tricas de uma mol?cula de DNA dupla fita. O modelo te?rico considerado faz uso de um Hamiltoniano efetivo com aproxima??o de liga??o-forte descrevendo um el?tron movendo-se em uma cadeia com um simples orbital por s?tio e intera??es entre vizinhos mais pr?ximos, juntamente com a equa??o de Schrodinger, e a muito conveniente t?cnica da matriz de transfer?ncia
17

Optimalizace bezdrátových WiFi distribuovaných sítí / Optimization of WiFi Distributed Nets

Žlůva, Ivan January 2009 (has links)
This thesis describes theoretic proposal and two practical realization of multi - point wireless network, first for communications between two endpoints and second for wireless signal coverage of a structured space. The wireless network is realized by the equipment working in unlicenced 2,4GHz and 5GHz ISM band. The wireless device are configured in three different wireless mods: WDS, WDS bridge and AP. This paper contains short information about IEEE 802.11a/b/g/n standard and associated proprietary wireless specifications. Practical workshop describes several variants connections and present the result of throughtput measurements, depending on wireless network topology.
18

Sub-Grain Characterization of Slip Activity in BCC Tantalum

Russell, Tristan Kirby 07 April 2022 (has links)
BCC metals are commonly used throughout the world and understanding their deformation behavior, especially at the sub-grain level, is essential for their continued use in technological advancements. Correctly and confidently characterizing the active slip systems in BCC materials has been a difficult task throughout past research. The research described in this thesis utilizes high resolution digital image correlation (HRDIC) and relative displacement ratio (RDR) analysis to accurately characterize active slip systems in large grained BCC tantalum and provides new insights into dislocation nucleation sites, relative CRSS values for {110} and {112} slip systems, the correlation between GB transmission factors and strain gradients, the relative length of NBGZs, and slip transmission. A 99.99% pure tantalum oligo sample was sputtered with gold and remodeled to provide high resolution data points to be used in HRDIC. The high resolution of the gold remodeled samples combined with a RDR analysis made it possible to confidently identify active slip systems during tensile deformation at room temperature. One of the observations from this analysis was the discrepancy between the observed active slip systems and those predicted from a simple single-CRSS Schmid's Law. By considering the active systems observed in grains with a range of orientation, it was concluded that the {112} slip systems have a higher CRSS than the {110} by 6.7%. Independent CPFE simulations and experiments on single crystal samples of the same material, agreed with our findings establishing a range of increased CRSS for {112} of 3.9%-7.1%. These conclusions are compared with the small number of available estimates of the CRSS ratio, and lie in between the value of equal CRSS used by most modelers, and experimental estimates of 15-25% higher for {112}. The identified active slip systems were also used in the Luster and Morris equation to calculate each GBs transmissivity factor - an estimate of strain incompatibility between neighboring grains. Results indicate that there is an inverse correlation between GB transmissivity and strain gradient slope, as well as a positive correlation between GB transmissivity and slip trace reorientation for some GBs. Only one instance of slip transmission was observed from the 24 GBs analyzed, suggesting it is an uncommon occurrence in BCC tantalum. An analysis of the length of the NBGZ in relation to slip and strain gradients was compared to previous studies and suggests the relative and absolute length of the NBGZ changes with grain size, at least for large length scales. Strain gradients for each side of the GB were measured and results indicated steep negative strain gradient slopes that suggest dislocation nucleation in the GBs and propagation towards the interior of the grain. When compared against the transmissivity factor, an inverse relationship was found to exist between strain gradients and high transmissivity factors.
19

Optimalizace bezdrátových WiFi distribuovaných sítí / Optimization of WiFi Distributed Nets

Žlůva, Ivan January 2010 (has links)
This thesis describes theoretic proposal and two practical realization of multi - point wireless network, first for communications between two endpoints and second for wireless signal coverage of a structured space. The wireless network is realized by the equipment working in unlicenced 2,4GHz and 5GHz ISM band. The wireless device are configured in three different wireless mods: WDS, WDS bridge and AP. This paper contains short information about IEEE 802.11a/b/g/n standard and associated proprietary wireless specifications. Practical workshop describes several variants connections and present the result of throughtput measurements, depending on wireless network topology.
20

Quantifying high-resolution hydrologic parameters at the basin scale using InSAR and inverse modeling, Las Vegas Valley, NV

Zhang, Meijing 10 November 2014 (has links)
The overall goal of this dissertation is to determine and develop optimal strategies for inversely calibrating transmissivities (T), elastic and inelastic skeletal storage coefficients (Ske and Skv) of the developed-zone aquifer and conductance (CR) of the basin-fill faults for the entire Las Vegas basin, and to investigate future trends of land subsidence in Las Vegas Valley. This dissertation consists of three separate stand-alone chapters. Chapter 2 presents a discrete adjoint parameter estimation (APE) algorithm for automatically identifying suitable hydraulic parameter zonations from hydraulic head and subsidence measurements. Chapter 3 compares three different inversion strategies to determine the most accurate and computationally efficient method for estimating T and Ske and Skv at the basin scale: the zonation method (ZM), the adaptive multi-scale method and the Differential Evolution Adaptive Metropolis Markov chain Monte Carlo scheme (DREAM MCMC). Chapter 4 outlines a fine-scale numerical model capable of capturing far more hydrologic detail than any previously developed model of Las Vegas Valley The new model is calibrated using high-resolution InSAR data and hydraulic head data from 1912 to 2010. The calibrated model is used to investigate the influence of faults and their potential role on influencing clay thicknesses and land subsidence distributions, and to investigate future trends of land subsidence in Las Vegas Valley. / Ph. D.

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