The effect of calcium uptake by hydration and diffusion from an adjacent calcium-rich soil on the performance of a geosynthetic clay liner (GCL) is examined for three cases. In Case 1 the GCL rested directly on a soil with a high calcium (1800 mg/l) concentration in the pore water (called “calcium rich soil” herein). Case 2 involved a GCL resting on 300 mm of soil with a low (200 - 300 mg/l) calcium concentration in the pore water (“foundation soil”) overlying the calcium rich soil. In the third (“control case”), the GCL only rested on the foundation soil. The overburden pressure was 15 kPa. The moisture content of GCL increased to 96%, 86% and 108% in the first 279 days for Cases 1, 2 and 3 respectively. Under isothermal conditions, the GCL moisture content decreased to 80% and 67% for Cases 1 and 2 respectively and increased to 113% for Case 3. After 1100 days, the hydraulic conductivity (k) of the GCL was 4×10-11 m/s for Case 3 but had increased up to about 7×10-11 m/s and 2×10-10 m/s for cases with and without the foundation layer respectively. The results are used to calibrate finite element models. A good correlation was found between k the bulk void ratio (eB) of GCL. Leakage and contaminant transport through 10 mm diameter hole in a geomembrane in a composite liner involving a GCL is examined at a stress of 100 kPa for hydraulic heads of 0.3 or 1 m. When permeated with distilled water, the interface transmissivity (θ) was about 2.3 × 10 11 m2/s. After 800 days of permeation with 0.14M NaCl there was only about 3% increase in the flow despite an order of magnitude increase in GCL permeability near the hole because θ decreased from 2.3×10-11 m2/s to 1.1×10-11 m2/s and controlled the leakage despite the increase in GCL permeability. Numerical modeling demonstrated reasonable agreement with the observed transport. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2010-09-09 12:20:42.298

Neste trabalho analisa-se o comportamento de duas configurações de liners através da percolação com solução de \'K\'CL\'. São utilizadas amostras de solo compactadas, do interior do estado de São Paulo, provenientes da Formação Corumbataí, combinadas a um geocomposto bentonítico (GCL) de fabricação nacional. São utilizados ensaios em coluna de percolação em dois corpos-de-prova, nas configurações: solo compactado acima do GCL e solo compactado abaixo do GCL. Esses ensaios permitiram a determinação da condutividade hidráulica e dos parâmetros de transporte dos materiais estudados. Dessa forma, compara-se o comportamento desses materiais combinados com os resultados obtidos por Musso (2008), que adotou a configuração independente. Após o início da percolação com solução \'K\'CL\' a condutividade hidráulica (\'K\') das duas configurações apresentou comportamento crescente. No entanto, este aumento no \'K\' não afetou o desempenho hidráulico dos materiais, e a condutividade hidráulica mostrou-se com valores da ordem de \'10 POT.-11\' m/s. O fator de retardamento da configuração na qual o GCL encontra-se acima da camada de solo compactado se mostrou maior com relação à outra configuração analisada. No geral, considerou-se que esta configuração apresentou melhor desempenho como liner composto. Na comparação dos resultados obtidos nesta pesquisa com os apresentados por Musso (op. cit.) a condutividade hidráulica não diferiu, e as configurações de liner compostos apresentaram maiores fatores de retardamento do que o liner do solo compactado isoladamente. / This research analyzes the behavior of two sets of liners subjected to the percolation of \'K\'CL\' solution. Samples of compacted soil from Corumbataí Formation, combined with a geosynthetic clay liner (GCL) of brazilian manufacture were used. Column percolation tests were used in two specimens, in the settings: compacted soil above the GCL and compacted soil below the GCL. These tests allowed the determination of hydraulic conductivity and transport parameters of the materials under study. Thus, the behavior of these composite liners was compared with the results obtained by Musso (2008), which tested the independent configuration. After the start of percolation of the \'K\'CL\' solution the hydraulic conductivity (\'K\') of the two settings showed an increase. However, this increase in \'K\' did not affect the hydraulic performance of materials, and the hydraulic conductivity was observed with values of about \'10 POT.-11\' m/s. The retardation factor of the configuration in which the GCL is above the layer of compacted soil was larger in relation to the other configuration analyzed. Overall, it was considered that this configuration showed better performance as composite liner. Comparing the results with those presented by Musso (2008), the hydraulic conductivity didn\'t differ, and the composite liners had higher retardation factors than the liner of compacted soil alone.

Neste trabalho analisa-se o comportamento de duas configurações de liners através da percolação com solução de \'K\'CL\'. São utilizadas amostras de solo compactadas, do interior do estado de São Paulo, provenientes da Formação Corumbataí, combinadas a um geocomposto bentonítico (GCL) de fabricação nacional. São utilizados ensaios em coluna de percolação em dois corpos-de-prova, nas configurações: solo compactado acima do GCL e solo compactado abaixo do GCL. Esses ensaios permitiram a determinação da condutividade hidráulica e dos parâmetros de transporte dos materiais estudados. Dessa forma, compara-se o comportamento desses materiais combinados com os resultados obtidos por Musso (2008), que adotou a configuração independente. Após o início da percolação com solução \'K\'CL\' a condutividade hidráulica (\'K\') das duas configurações apresentou comportamento crescente. No entanto, este aumento no \'K\' não afetou o desempenho hidráulico dos materiais, e a condutividade hidráulica mostrou-se com valores da ordem de \'10 POT.-11\' m/s. O fator de retardamento da configuração na qual o GCL encontra-se acima da camada de solo compactado se mostrou maior com relação à outra configuração analisada. No geral, considerou-se que esta configuração apresentou melhor desempenho como liner composto. Na comparação dos resultados obtidos nesta pesquisa com os apresentados por Musso (op. cit.) a condutividade hidráulica não diferiu, e as configurações de liner compostos apresentaram maiores fatores de retardamento do que o liner do solo compactado isoladamente. / This research analyzes the behavior of two sets of liners subjected to the percolation of \'K\'CL\' solution. Samples of compacted soil from Corumbataí Formation, combined with a geosynthetic clay liner (GCL) of brazilian manufacture were used. Column percolation tests were used in two specimens, in the settings: compacted soil above the GCL and compacted soil below the GCL. These tests allowed the determination of hydraulic conductivity and transport parameters of the materials under study. Thus, the behavior of these composite liners was compared with the results obtained by Musso (2008), which tested the independent configuration. After the start of percolation of the \'K\'CL\' solution the hydraulic conductivity (\'K\') of the two settings showed an increase. However, this increase in \'K\' did not affect the hydraulic performance of materials, and the hydraulic conductivity was observed with values of about \'10 POT.-11\' m/s. The retardation factor of the configuration in which the GCL is above the layer of compacted soil was larger in relation to the other configuration analyzed. Overall, it was considered that this configuration showed better performance as composite liner. Comparing the results with those presented by Musso (2008), the hydraulic conductivity didn\'t differ, and the composite liners had higher retardation factors than the liner of compacted soil alone.

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During the race towards the4th generation (4G) cellular-based digital communication systems, a growth in the demand for high capacity, multi-media capable, improved Quality-of-Service (QoS) mobile communication systems have caused the developing mobile communications world to turn towards betterMultiple Access (MA) techniques, like Code Division Multiple Access (CDMA) [5]. The demand for higher throughput and better QoS in future 4G systems have also given rise to a scheme that is becoming ever more popular for use in these so-called ‘bandwidth-on-demand’ systems. This scheme is known as adaptive channel coding, and gives a system the ability to firstly sense changes in conditions, and secondly, to adapt to these changes, exploiting the fact that under good channel conditions, a very simple or even no channel coding scheme can be used for Forward Error Correction(FEC). This will ultimately result in better system throughput utilization. One such scheme, known as incremental redundancy, is already implemented in the Enhanced Data Rates for GSM Evolution (EDGE) standard. This study presents an extensive simulation study of a Multi-User (MU), adaptive channel coded Direct Sequence Spread Spectrum Multiple Access (DS/SSMA) communication system. This study firstly presents and utilizes a complex Base Band(BB) DS/SSMA transmitter model, aimed at user data diversity [6] in order to realize the MU input data to the system. This transmitter employs sophisticated double-sideband (DSB)Constant-Envelope Linearly Interpolated Root-of-Unity (CE-LI-RU) filtered General Chirp-Like (GCL) sequences [34, 37, 38] to band limit and spread user data. It then utilizes a fully user-definable, complex Multipath Fading Channel Simulator(MFCS), first presented by Staphorst [3], which is capable of reproducing all of the physical attributes of realistic mobile fading channels. Next, this study presents a matching DS/SSMA receiver structure that aims to optimally recover user data from the channel, ensuring the achievement of data diversity. In order to provide the basic channel coding functionality needed by the system of this study, three simple, but well-known channel coding schemes are investigated and employed. These are: binary Hamming (7,4,3) block code, (15,7,5) binary Bose-Chadhuri-Hocquenghem (BCH) block code and a rate 1/3 <i.Non-Systematic (NS) binary convolutional code [6]. The first step towards the realization of any adaptive channel coded system is the ability to measure channel conditions as fast as possible, without the loss of accuracy or inclusion of known data. In 1965, Gooding presented a paper in which he described a technique that measures communication conditions at the receiving end of a system through a device called a Performance Monitoring Unit (PMU) [12, 13]. This device accelerates the system’sBit Error Rate (BER) to a so-called Pseudo Error Rate(PER) through a process known as threshold modification. It then uses a simple PER extrapolation algorithm to estimate the system’s true BER with moderate accuracy and without the need for known data. This study extends the work of Gooding by applying his technique to the DS/SSMA system that utilizes a generic Soft-Output Viterbi Algorithm(SOVA) decoder [39] structure for the trellis decoding of the binary linear block codes [3, 41-50], as well as binary convolutional codes mentioned, over realistic MU frequency selective channel conditions. This application will grant the system the ability to sense changes in communication conditions through real-time BER measurement and, ultimately, to adapt to these changes by switching to different channel codes. Because no previous literature exists on this application, this work is considered novel. Extensive simulation results also investigate the linearity of the PER vs. modified threshold relationship for uncoded, as well as all coded cases. These simulations are all done for single, as well as multiple user systems. This study also provides extensive simulation results that investigate the calculation accuracy and speed advantages that Gooding’s technique possesses over that of the classic Monte-Carlo technique for BER estimation. These simulations also consider uncoded and coded cases, as well as single and multiple users. Finally, this study investigates the experimental real-time performance of the fully functional MU, adaptive coded, DS/SSMA communication system over varying channel conditions. During this part of the study, the channel conditions are varied over time, and the system’s adaptation (channel code switching) performance is observed through a real-time observation of the system’s estimated BER. This study also extends into cases with multiple system users. Since the adaptive coded system of this study does not require known data sequences (training sequences), inclusion of Gooding’s technique for real-time BER estimation through threshold modification and PER extrapolation in future 4G adaptive systems will enable better Quality-of-Service (QoS) management without sacrificing throughput. Furthermore, this study proves that when Gooding’s technique is applied to a coded system with a soft-output, it can be an effective technique for QoS monitoring, and should be considered in 4G systems of the future. / Dissertation (MEng (Computer Engineering))--University of Pretoria, 2007. / Electrical, Electronic and Computer Engineering / MEng / unrestricted