The need for conducting real-time bridge deformation monitoring is addressed in the context of the development of bridge management system (BMS) and land transportation safety in this thesis. Current instruments used for bridge dynamic deformation monitoring are compared in terms of system productivity and reliability. An integrated sensor system of Global Positioning System (GPS) receiver and triaxial accelerometer is then proposed with the capabilities to accurately monitor long-term deformation and short-term dynamics of a bridge. Since the investigation of the bridge dynamic responses is of great importance in research and practice, the emphasis of this thesis is on the monitoring of dynamic bridge deformation. Zero baseline (ZBL) and short baseline (SBL) tests are conducted to evaluate the performance of three types of Leica GPS receivers at 10 Hz sampling rate. Statistic characteristics of positioning solutions and the achievable accuracy of each receiver type are analysed, which are employed to design optimal filters for various GPS error suppressions. By using a moving average (MA) technique, millimetre baseline accuracy can be achieved even with a single frequency receiver. It demonstrates the possibilities to conduct millimetre bridge deformation monitoring if appropriate filtering techniques are applied to the positioning solutions and integer ambiguity has been fixed. A simple but accurate triaxial accelerometer calibration technique is proposed in the thesis with a solid mathematical derivative to evaluate the precisions of estimated parameter offsets. A specially designed cage is used to house a GPS antenna with a triaxial accelerometer to avoid complex sensor alignment and simplify the coordinate transformations between different reference frames. The determination of instantaneous attitude of an accelerometer body frame is realised by three GPS stations on the deck of a bridge at a rate of 10 Hz and the sensed 3D accelerations are then transformed into a bridge coordinate system (BCS) simultaneously. BCS is the computation frame of a hybrid bridge deformation monitoring system (BDMS). Important issues in sensor integration such as local gravity determination, synchronisation of time series from different sensors are addressed. Bridge trials are briefed with the emphasis on the instrument configuration for effective error mitigation and sensor integration. A group of reference stations consisting of two reference stations closely setup near a bridge and the permanent continuous GPS stations are recommended for reducing relative tropospheric delay, multipath, and receiver noise both at reference stations and monitoring sites. GPS satellite sky distribution and its impact on propagating ranging errors in mid latitude areas such as in the UK and high latitude areas are analysed both with analytical and simulation approaches. The error propagation formulae are derived to analyse the defects of current satellite constellation on the GPS positioning solutions in each direction of a BCS. This is further exploited to improve the component accuracy of particular interest through changing the dilution of precision (DOP) values. The degree of positioning improvement is illustrated with GPS/GLONASS positioning. A simulator according to ranging error propagation is used to simulate the achievable accuracy from the best and the worst GPS constellations. Modified precise satellite ephemeris by inserting the positions of pseudolites is employed to investigate the changes of DOP values in each direction of a BCS. The summaries of this simulation have universe significance in guiding the selection of the best locations of pseudolites. Adaptive Finite Impulse Response (FIR) filtering or adaptive filtering (AF) for short and important application issues are addressed in the thesis. Autocorrelation lags of ZBL and SBL tests of each type of receiver are used to determine the filter lengths according to the fundamentals of low pass and high pass filter designs. A real-time AF algorithm is introduced and widely employed as an analytical tool in the error mitigation and real bridge deformation signal extraction. The application defects of MA technique in bridge deformation monitoring are compared with AF approach according to the component analysis of GPS positioning solutions. A recursive AF algorithm is proposed to gradually isolate actual bridge deflection signals from multipath and receiver noise both at reference stations and monitoring sites. Spectral analysis is applied to the input and output signals to investigate the efficiency of the designed filter. In order to effectively isolate actual bridge deformation, misalignment and its consequence are demonstrated with day-to-day shifted time series of bridge deflection. Cross-correlation is also used to analyse the feasibility and efficiency of the proposed AF algorithm. Acceleration aided AF approach is detailed in the thesis. A simple algorithm, based on the principles of digital signal filtering and optimal filter design, is proposed to estimate relative displacements of bridge sensed by a triaxial accelerometer in three dimensions. With the relative displacements, GPS receiver noise has been filtered out and the cleaned displacements are obtained. AS another data fusion approach, a software package based on discrete Fourier transform (DFT) to integrate GPS and accelerometer data with a position output rate up to that of a triaxial accelerometer is introduced. Relative tropospheric delay is another major error source identified in GPS-based bridge deformation monitoring. Methods applied to distinguish the impacts of multipath and tropospheric delay are presented. The cause for relative tropospheric delay is analysed and microclimate effect is recognised as the major impact factor in this particular environment. Numerical calculations also confirm the assumption. The way to effectively remove relative tropospheric delay is recommended. The research emphasis in this thesis is to develop a prototype of a hybrid BDMS to achieve centimetre level positioning accuracy at each epoch in three dimension of a BCS. The findings from this research are summarised and the future work is predicted.

In January 1999, the maximum axle weight increased from IN to 11.5t for the assessmenot f highway bridges and structures. At the samet ime, the maximum vehicle weight also increased from 38t to 44t. Highway authorities are urgently searching for a more refined assessmenmt ethod to predict the behaviour of masonry arch bridges. LUSAS finite element analysis was used to study the behaviour of masonry arch bridges. Load versus deflection curves and collapse loads are given for some of the full and large scale arches previously tested to collapse. A parametric study was also performed to determine the influence of the arch material properties and the load dispersal angle: the arch tensile strength and the load dispersal angle were found to have the most significant influence on the collapse load predictions. Repeatability tests were carried out by building three nominally identical large scale arch bridges in the laboratory and testing them to collapse. The first, second and third arches collapsed at 2lkNm', 16kNm', and 25kNm 1 respectively. Finite element analysis predicted a range of 18kNm' to 39kNm 1 for the same arches. This led to an examination of a statistical, risk based, approach to bridge assessment. Two novel risk assessment programs were developed by integrating Monte Carlo simulation with the MEXE and the mechanism methods. Statistical information about the predicted collapse load and allowable axle load is given. These risk assessment tools are offered for incorporation within routine assessmenmt ethods. Their principal benefit lies in providing engineers with a feel for the reliability of their analyses. A modification has been made to the mechanism method by considering arch deflection. A mechanism prediction is accurate only when all the forces and their positions are accurately located. The modified mechanism method was used to analyse some of the full scale arch bridges, previously tested to collapse, which revealed that arch deflections had a significant influence on the collapse load prediction.

The dynamic response of highway bridges is a topic that has been thoroughly researched over many years. However, understanding of how the dynamic response of bridges is affected by the performance of their bearings over an extended period of time is, at present, not clearly defined. Although health monitoring of bridge structures is relatively advanced, the scope for further research is wide. The study presented in this thesis contains research on plate structures; ranging from a simple Euler-Bernoulli method to determine natural frequencies; modal analysis of a plate structure in the laboratory; FEA of the plate structure; modal analysis on a full-scale structure subjected to vehicle loading; and FEA of a simplified model representing the full-scale structure. A combination of these methods has allowed the conclusions presented herein to be drawn with respect to the effects of support degradation, and the consequent effect on structural performance. In the laboratory, modal analysis of a small-scale, thin rectangular plate of Perspex' has been completed. A series of boundary conditions have been investigated through altering the support offered to the plate by a series of springs, each with a different stiffness, to simulate bearings with different stiffnesses. Vibrations of varying frequency have also been forced upon the plate, and its response recorded. Displacement values provided the clearest indication of the effect of bearing stiffness, with the least stiff spring resulting in the largest displacement. Alteration of support stiffness in the model can have a marked effect on the resonant frequency of the plate (approx. 23 % frequency change between spring 1 (1.22 Nmm 1) and 5 (15.62 Nmm 1)). Full-scale testing on a highway bridge at Berwick-upon-Tweed on the Al, over the River Tweed, was completed in May 2005. These data form the baseline for future dynamic testing and condition monitoring of the structure. To describe the dynamic properties of the structure, the force generated by each type of vehicle traversing the structure was determined using instrumentation already in place on the bridge. Statistics drawn from the data are presented, which indicate that the bearings are functioning as expected, but are subjected to forces of a much larger magnitude due to overloaded HGVs than in current design specifications. Larger HGVs made up a small percentage of overall vehicles recorded, but contribute a much higher proportion of damage caused to the bridge. Displacement and frequency were both valid measures of bearing performance and therefore state of degradation. The method is offered as a condition monitoring test for bridges and their bearings.

Expansion joints and bearings of conventional bridges are easily damaged and this commonly incurs high maintenance costs. The concept of the integral bridge was to reduce the maintenance costs by removing those joints. However, the thermally induced expansion-contraction of the bridge superstructure is transferred through the integral bridge’s abutments due to lack of expansion joints. Seasonal thermal cyclic displacement of the integral abutment cyclically loads the bridge backfill material. It has been observed that the lateral earth pressure behind an integral abutment increases as a result of the cyclic loading. Previous studies attribute this increase in lateral pressure to the densification of the backfill material. Granular flow was suggested to have occurred displacing the particles to form a denser and therefore stiffer matrix. An alternative suggestion was that the particles reoriented to form a stiffer matrix that wasn’t necessarily denser. The objective of this research is to explore the behaviour of integral abutment backfill at a micromechanical level by utilising the discrete element method (DEM) and possibly verify these suggested causes of earth pressure build-up behind an integral abutment. DEM models of four granular materials consisting of different particle shapes were tested with 100 cycles of strain. The results indicate that densification occurred for all samples, but the build-up of horizontal pressure did not occur for the more rounded samples. It was further suggested that the particle shape in combination with the change in coordination number closely replicate the behaviour of the sample’s horizontal stress. Particle reorientation and displacements were observed to be small for samples of non-circular particles. Particle activity is concentrated in the smallest particles within the material. It is concluded that the build-up of horizontal stress is caused by the increase in particle contacts due to particle reorientation and not densification.

As a the limit-cycle oscillation, vortex-induced vibration (VIV) does not cause catastrophic failure but it can lead to fatigue in long and slender structures and structural elements, especially for long span bridges. Assessing this behaviour during the design stage is therefore very important to ensure the safety and serviceability of a structure. Currently, this task requires very time-consuming wind tunnel or computational simulation since a reliable mathematical model is not available. Moreover, knowledge of the underlying physical mechanism of the VIV and, particularly, of the turbulence-induced effect on the VIV is insufficient. Turbulence is normally considered to produce suppressing effects on the VIV; however, this influence appears to depend on cross sections and a comprehensive explanation is yet to be found. This issue can be resulted from some limitation that most wind tunnel or computational studies have used sectional models. The flow field is therefore dominated by 2D flow features. In this research study, the 5:1 rectangular cylinder is selected as the case study since it is considered as the generic bride deck geometry. Using the wind tunnel at the University of Nottingham, a series of wind tunnel tests using a static and elastically supported sectional model is conducted in smooth flow. This wind tunnel study is complemented by a computational study of a static and dynamic sectional model; the computational simulations are carried out using the Computational Fluid Dynamics software OpenFOAM and the High Performance Computer system at the University of Nottingham. A Fluid-structure-interaction (FSI) solver is built to model the heaving VIV. By comparing the surface pressure measurement between these two studies, it uncovers the two separate flow mechanisms and associated flow features, which are both responsible for the VIV. The series of wind tunnel static and dynamic tests is also repeated in different turbulent flow regimes. By analysing the forces, moment, surface pressure and structural response, it reveals the mechanism of the turbulence-induced effect on the aerodynamic characteristics as well as on VIV. By improving the proposed FSI solver, a novel computational approach is introduced to simulate the VIV of a flexible 5:1 rectangular cylinder excited at the first bending mode shape. Employing the Proper Orthogonal Decomposition (POD) technique and comparing against results of the sectional model, some emerging span-wise flow features are revealed together with their influences on the mechanism of the bending VIV. The Hartlen and Currie mathematical model for the VIV is generalised so that it is able to simulate the VIV response of a 3D flexible structure. Such modifications and improvements are originated from and assessed by results of the computational simulation of the flexible model. A case study of the Great Belt East bridge is then carried out to verify this modified model.

INTRODUCTION: Blood lipids, more precisely triglycerides (TG), are important fuel sources that are highly regulated since an exaggerate amount can lead to cardiovascular diseases. TG breakdown after a meal is mainly controlled by an enzyme expressed in adipose tissue called lipoprotein lipase (LPL). Recent evidence in animals report that adipose tissue LPL is inhibited after an exposure to an environment with reduced oxygen content, leading to a raised level of plasmatic TG. The objective of this thesis was to characterize the effects of an acute exposure to hypoxia on the plasmatic lipolytic activity level and on postprandial TG levels in humans. It was hypothesized that postprandial TG level and plasmatic lipolytic activity, a proxy of LPL activity, would be negatively affected by hypoxia. METHODS: Postprandial TG, non-esterified fatty acid (NEFA), glucose levels, and postheparin plasmatic lipolytic activity were measured on healthy young men (n=7) exposed for 6 h to either control (FiO2=0.2093) or hypoxia (FiO2=0.1200) in a randomized crossover fashion. RESULTS: Exposure to acute hypoxia led to a close to significant (p = .06) increase in postprandial plasmatic TG level and significant postprandial NEFA levels. Postprandial glucose levels were not affected by acute exposure to hypoxia. A significant increase in postheparin plasmatic lipolytic activity was observed after acute hypoxia exposure as compared to the control condition. CONCLUSION: Acute hypoxia in healthy men tend to negatively affects postprandial TG level while increasing plasmatic lipolytic activity. These results lend support to the increased blood lipid levels reported in individuals exposed to lower partial pressure of oxygen during sojourn at high altitude.

Submitted by Jaqueline Silva (jtas29@gmail.com) on 2014-10-06T18:08:43Z No. of bitstreams: 2 Dissertação - Thaíza Carvalho da Rocha - 2012.pdf: 1513291 bytes, checksum: 5cdef676b716525fc5590bddb862c72f (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Jaqueline Silva (jtas29@gmail.com) on 2014-10-06T19:16:52Z (GMT) No. of bitstreams: 2 Dissertação - Thaíza Carvalho da Rocha - 2012.pdf: 1513291 bytes, checksum: 5cdef676b716525fc5590bddb862c72f (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2014-10-06T19:16:52Z (GMT). No. of bitstreams: 2 Dissertação - Thaíza Carvalho da Rocha - 2012.pdf: 1513291 bytes, checksum: 5cdef676b716525fc5590bddb862c72f (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2012-05-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Thermal analysis techniques have been very useful to study the pre-formulations since it consists in techniques that can provide quick and reliable results. This study evaluated the thermoanalytical profiles of psoralen and bergapten, compounds used in the treatment of vitiligo, and their interactions with excipients. We also evaluated the thermal profile of the plant extract Brosimum gaudichaudii Trécul (Moraceae) and a medicine containing the same extract. The results showed that psoralen and bergapten are substances with decomposition and have only one melting step at 162 ° C and 190 respectively. The compounds psoralen and bergapten interact with each other, but the results by XRD clearly show that the crystal structures of the compounds are not affected by these interactions. Furthermore, the results of thermal analysis showed that there was no interaction with the excipients of these compounds under study. All results were confirmed by FT-IR, used as a complementary technique. The plant extract showed an endothermic event which can be attributed to the fusion of these assets. The DSC curve profile of the drug trade allowed the detection of lactose in their composition, whose presence is not included in the package leaflet. / As técnicas de análise térmica tem se mostrado muito úteis no estudo de pré-formulações visto que consiste em técnicas que apresentam resultados rápidos e seguros. Neste trabalho foram avaliados os perfis termoanalíticos do psoraleno e bergapteno, compostos utilizados no tratamento de vitiligo, e suas interações com excipientes. Avaliou-se também o perfil térmico do extrato da planta Brosimum gaudichaudii Trécul (Moraceae) e de um medicamento contendo o mesmo extrato. Os resultados mostraram que psoraleno e bergapteno são substâncias que possuem decomposição em apenas uma etapa e apresentam fusão em 162 e 190 °C, respectivamente. Os compostos psoraleno e bergapteno interagem entre si, mas os resultados através de DRX deixam claro que as estruturas cristalinas dos compostos não são afetadas por essas interações. Além disso, os resultados obtidos com a análise térmica evidenciam que não ocorreu nenhuma interação destes compostos com os excipientes em estudo. Todos os resultados foram confirmados por FT-IR, utilizada como técnica complementar. O extrato da planta mostrou um evento endotérmico que pode ser atribuído à fusão dos ativos presentes. O perfil da curva DSC do medicamento comercial possibilitou a detecção da lactose em sua composição, cuja presença não consta na bula do medicamento.

Os procedimentos braquiterápicos atuais seguem as diretrizes apresentadas no protocolo da AAPM TG - 43, introduzido em 1995, que define a metodologia de cálculo de dose ao redor de fontes encapsuladas. Este protocolo, dentre outras considerações, adota a água como meio dosimétrico padrão e desconsidera a composição dos tecidos, densidades e dimensões do paciente nas estimativas de dose absorvida. Com o objetivo de realizar os cálculos de dose em condições mais próximas à realidade, a AAPM publicou em 2012 o TG-186, que introduz os algoritmos de cálculos de dose baseados em modelos na braquiterapia (MBDCA- model-based dose calculation algorithm). Estes algoritmos são capazes de considerar as complexidades descritas acima, além de permitirem estimativas de dose diretamente nos tecidos biológicos. Apesar deste advento, ainda há controvérsia sobre a melhor forma de se reportar a dose absorvida, com pontos favoráveis tanto para estimativas de dose na água, quanto nos tecidos. Esta tese se insere dentro deste contexto, buscando a correlação entre todo o conhecimento previamente adquirido baseado em água com os modernos algoritmos de cálculo de dose. A relação entre a dose na água e no meio é realizada através da teoria da cavidade, que assume que a fluência dos fótons na água e no meio é idêntica. Parte dos objetivos do presente trabalho foi avaliar a fluência energética de fótons em diferentes meios irradiados com fontes braquiterápicas de energias baixas (<50,0 keV), propondo uma forma eficiente de correlacionar a dose na água e no meio em situações nas quais a fluência dos fótons é relevante. Avaliou-se a dose absorvida na água e em diferentes tecidos humanos, para quantificar fatores de conversão entre as estimativas de dose, simulados por Monte Carlo. Para validar tais fatores foi proposta uma metodologia experimental com o uso de um objeto simulador, desenvolvido especificamente para a realização deste trabalho e com capacidade de medir os efeitos da heterogeneidade do meio utilizando doses absorvidas em dosímetros termoluminescentes. As correções baseadas na fluência energética obtidas neste estudo, quando necessárias, são capazes de correlacionar a dose absorvida no tecido e na água com uma precisão melhor do que 0,5 % nos casos mais críticos (ex. osso). Os fatores de conversão calculados mostraram que a dose absorvida na água subestima a dose absorvida no osso em até 80 %, mas superestima a dose no tecido adiposo em aproximadamente 75 %, ressaltando a necessidade de se considerar a composição e a densidade do meio nas estimativas de dose. Os resultados experimentais permitiram validar os fatores de conversão de dose simulados com diferenças máximas de 8,5 %, entre os valores experimentais e simulados. Todos os resultados obtidos comprovaram que a estimativa da dose absorvida em procedimentos braquiterápicos com baixas energias diferem significativamente quando realizadas na água e nos tecidos biológicos, evidenciando a necessidade do uso de algoritmos que considerem a heterogeneidade do meio. Tais resultados também enfatizaram a necessidade de se considerar com precisão a composição do corpo, uma vez que variações nas composições médias dos tecidos podem afetar as estimativas dosimétricas e aumentar as incertezas dos resultados. / Brachytherapy treatments are commonly performed using the American Association of Physicists in Medicine (AAPM) Task Group report TG-43, introduced in 1995, which defines the formalism for the calculation of absorbed dose to water, and neglects human tissue densities, material compositions, body interfaces, body shape and dose perturbations from applicators. In order to perform dose calculations in conditions closer to reality, the AAPM published in 2012 the TG-186, which introduces the model-based dose calculation algorithm (MBDCA) in brachytherapy. These algorithms are able to consider the complexities described above, in addition, it allows dose estimates directly into biological tissues. Despite the advent, the best way to report the absorbed dose is still a matter of debate, with favourable points for both water and tissue absorbed dose estimates. The present thesis is inserted within this context, searching for the correlation between all previously acquired knowledge based in absorbed dose to water with the absorbed dose calculated using modern MBDCA. The correlation between the doses in water and the doses in tissue is performed through the cavity theory, which generally assumes that the fluence of the photons in water and in tissue are identical. Part of the purpose of the present work was to evaluate the energy-fluence of photons in different medium irradiated with low energy brachytherapy sources (<50,0 keV), proposing an efficient way to correlate absorbed dose to water and absorbed dose to tissue in brachytherapy in situations in which the fluence of the photons is relevant. In addition to this objective, the dose absorbed in water and in different human tissues was evaluated to quantify conversion factors between these dose estimates, simulated by Monte Carlo. To validate such factors, an experimental methodology was proposed in a phantom with the capacity to quantify the effects of the heterogeneity of the medium measuring absorbed doses in thermoluminescent dosimeters. The energy-fluence based corrections given in this work, when necessary, are able to correlate the absorbed dose to tissue and absorbed dose to water with an accuracy better than 0.5 % in the most critical cases (e.g.: bone tissue). The calculated conversion factors showed that the absorbed dose to water underestimates the absorbed dose to bone by up to 80 % but overestimates the dose in adipose tissue by approximately 75 %, emphasizing the need to consider the composition and the density of tissue in the dose estimates. The experimental results allowed validating the simulated conversion factors with maximum differences of 8.5 % between the experimental and simulated dose values. All the results obtained showed that the estimation of the dose absorbed in low energy brachytherapy procedures differ significantly when performed in water and in biological tissues, evidencing the necessity of using MBDCA. These results also emphasized the need to accurately consider tissue composition, since the smallest variations in tissue compositions may affect dosimetric estimates and increase uncertainties of the results.

No description available.

Thermogravimetry, coupled with a mass spectrometer (TG-MS) was used to investigate the catalytic effect potassium carbonate (K2CO3) and potassium chloride (KCl), on the char conversion and the product gas composition of chars derived from a South African inertinite-rich bituminous coal. Sequential leaching of the coal with HCl-HF-HCl was performed to reduce the mineral matter present in the coal. This was done in order to reduce possible undesirable interactions between the minerals and inorganic compounds in the coal during heat treatments. The leaching process substantially reduced the ash content from 21.5% to less than 3%. K2CO3 and KCl [0.5, 1, 3, 5 K-wt %] were loaded to the demineralized coal, raw coal and demineralized coal with added mineral mixture prior to charring. The mineral mixture was made up of kaolinite, quartz, pyrite, siderite, calcite, anastase and hydromagnesite. The ‘doped’ coal samples were then subjected to heat treatments in a CO2 atmosphere up to 1200 °C. The results obtained showed that both K2CO3 and KCl exhibit a catalytic effect on the char conversion during heat treatments in CO2 atmosphere and the char conversion was increased with increasing loadings up to 5 K-wt% of K2CO3 and KCl. The temperature ranges at which conversion occurred were found to be lower for K2CO3 than for KCl. Subsequently, char conversion occurred over a relatively narrower temperature range for K2CO3 than observed for KCl. The catalytic behaviour of K2CO3 and KCl was confirmed by the results obtained. The results also indicated that the catalytic influence of K2CO3 is greater than that of KCl and that KCl is more susceptible to deactivation by minerals and inorganic compounds present in the coal than K2CO3. Different analytical techniques (XRF and XRD) were used to determine the extent of interaction of the catalysts used with the char material in the 5 K-wt% ‘doped’ coal samples. From the XRF results, it was observed that the K2O content was reduced after heat treatments in CO2, however, no potassium crystalline phases were observed in the XRD results after heat treatments in CO2. The reduced K2O content may be attributed to the potassium been taken up in other mineral matter during char reaction with CO2, forming new amorphous inorganic complex compounds. Thus the potassium retained in the sample after heat treatment, indicated by the XRF results, may be in an amorphous phase. Mass spectrometry (MS) indicated that temperatures at which the maximum rate of evolution of gaseous species occurred were relatively lower for K2CO3 loaded char samples iv than observed for KCl loaded samples. In addition, no mass-to-charge ratio (m/z) peak at 39 atomic mass unit (amu) from the MS results was observed, indicating that no potassium was detected in the gaseous phases for all the char samples. The undetected potassium in the gaseous phase may be due to the detection limit of the MS equipment. The MS results also indicated that addition of the catalyst facilitates the evolution of H2 from the coal char samples. Addition of the catalysts to the samples lowered the temperature at which maximum H2 was given off. The shift to lower temperatures was observed with increased catalyst loadings for both K2CO3 and KCl loaded samples. / Thesis (MSc (Chemistry))--North-West University, Potchefstroom Campus, 201