The aim of this thesis was to create a model of thermal conversion of solid fuel. This is achieved by means of standard modelling tools included in software ANSYS Fluent in combination with user-defined functions (UDF). In first part of thesis basic approaches to CFD modelling of solid fuel combustion are presented. Building of a mathematical model and corresponding algorithms follows. Individual parts of a created model and its parts are tested on simple physical cases and then on case of experimental reactor for analysing biomass combustion.

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This thesis aims to explore the two dominant functional roles of the hippocampal formation, in the relational encoding of episodic memory and the neural representation of allocentric space, using a combination of pharmaceutical manipulations and single-unit recording techniques in rodents. The first part of this thesis focuses on episodic-like memory, defined by the original episodic memory triad: ‘what-where-when’ (Tulving 1972), which enables the behavioural aspects of episodic memory to be tested in non-human animals. Permanent neurotoxic lesions of the hippocampus and it’s subregions were induced to assess their role in a putative episodic-like memory task developed by Eacott and Norman (2004). In view of the difficulties encountered in successfully demonstrating the temporal component of episodic-like memory in rats, this task tested integrated memory for ‘what-where-which’, where the temporal component (when) was replaced with another event specifier: context (on ‘which’ occasion). Disruption of the hippocampal circuitry led to a specific impairment in the integration of all three event components, whereas the associative recognition of any combination of these features in isolation was left intact. These results confirm the hippocampal dependence of this episodic-like memory task and further reveals the necessity of both CA3 and CA1, hypothetically due to the underlying autoassociative role of CA3 with CA1 functioning as the vital output pathway for this associated information and/or as a mismatch detector. There has been much debate over the inclusion of the temporal component and sceptics may argue that any such interpretations of task-dependence on episodic-like memory processing are invalid considering the requirement for temporal processing is absent. Due to the proposal that a temporal framework necessarily provides the foundation on which episodic memories are built, the second chapter focuses on the development of a suitable protocol in which integrated memory for the original ‘what-where-when’ episodic memory triad can be reliably tested. The other main function attributed to the hippocampus was brought to light by the fascinating revelation that it’s neurons selectively fire in different regions of an environment, termed ‘place cells’ (O’Keefe and Dostrovsky 1971). From the numerous publications resulting from this discovery it has emerged that place cells not only respond to the spatial features of the environment but are also sensitive to a multitude of non-spatial features. These characteristics support the logical assumption that the primary firing patterns of the hippocampus should underlie it’s main purported roles, leading to speculations that they reflect episodic memory processes. The second part of this thesis aims to examine the relationship between hippocampal cells and behaviour by extending the work of Ainge et al. (2007a), in which a subset of hippocampal place cells were found to encode both current and intended destination in a double Y-maze ‘win-stay’ task. The development of these ‘goal-sensitive’ cells were initially investigated during the learning phase of this task. An exciting pattern of results showed a strong positive correlation between the emergence of goal-sensitive firing and behavioural performance on the task, tempting speculations that these firing patterns may underlie spatial learning and future planning, necessary to support performance. To ensure these firing patterns were not a mere reflection of greater experience on the maze, a second study was conducted in which the task demands changed over set periods of days. A significant increase in the proportion of cells demonstrating goal-sensitive firing was revealed when the protocol shifted to incorporate the spatial memory demands of the ‘win-stay’ task, with all other parameters of the protocol remaining constant. These results support the theory that goal-sensitive firing patterns are specifically related to the learning and memory demands of the spatial task, not a result of increased exploration of the maze. The last of this series of studies assessed hippocampal-dependence of this task and revealed that bilateral hippocampal lesions induced an impairment in spatial ‘win-stay’ performance. Collectively, these experiments demonstrate that goal-sensitive firing of hippocampal cells emerge in line with behavioural performance in a hippocampal-dependent task and the emergence of these firing patterns are specific to the learning and memory demands of a spatial ‘win-stay’ protocol. The functional role of the hippocampus in allocentric spatial processing may thus underpin it’s function in episodic memory and potentially in the imagining and planning of future events, whereby the hippocampus provides a ‘space’ in which retrieved information can be integrated in a coherent context to support the fluent and flexible use of information. This hippocampal function would necessarily require visual information to be accessed, concerning the arrangement of landmarks and cues within the environment, in association with information regarding internal orientation and direction and this leads to the question assessed in the final part of this thesis of where this integration occurs. Based on anatomical evidence and the current literature, the postsubiculum, an input structure to the hippocampus, emerged as a potential site for the convergence of sensory cues into the internally generated head direction cell and place cell networks to enable hippocampal-dependent spatial processing. Thus, the effects of temporary pharmacological blockade of AMPARs and NMDARs in the postsubiculum were assessed on the encoding of spatial memory in an object recognition paradigm. The impairment revealed in the ability to recognise novel object-place configurations demonstrates a key role for NMDAR-dependent plasticity within the postsubiculum itself in the formation of allocentric spatial memory. In summary, the experimental results reported in this thesis further elucidate the critical role the hippocampal formation plays in spatial and episodic memory by combining evidence from cellular physiology and neuroanatomy to the behaving animal and extends these findings to discuss a more general role for the hippocampus in imagining both past and future events, in order to successfully navigate, learn and enable past experience to influence our intended future plans and decisions.

This thesis focuses on enhancing knowledge on co-firing oxy-combustion cycles to boost development of this valuable technology towards the aim of it becoming an integral part of the energy mix. For this goal, the present work has addressed the engineering issues with regards to operating a retrofitted multi-fuel combustor pilot plant, as well as the development of a rate-based simulation model designed using Aspen Plus®. This model can estimate the gas composition and adiabatic flame temperatures achieved in the oxy-combustion process using coal, biomass, and coal-biomass blends. The fuels used for this study have been Daw Mill coal, El Cerrejon coal and cereal co-product. A parametric study has been performed using the pilot-scale 100kWth oxy-combustor at Cranfield University and varying the percentage of recycle flue gas, the type of recycle flue gas (wet or dry), and the excess oxygen supplied to the burner under oxy-firing conditions. Experimental trials using co-firing with air were carried out as well in order to establish the reference cases. From these tests, experimental data on gas composition (including SO3 measurement), temperatures along the rig, heat flux in the radiative zone, ash deposits characterisation (using ESEM/EDX and XRD techniques), carbon in fly ash, and acid dew point in the recycle path (using an electrochemical noise probe), were obtained. It was clearly shown during the three experimental campaigns carried out, that a critical parameter was that of minimising the air ingress into the process as it was shown to change markedly the chemistry inside the oxy-combustor. Finally, part of the experimental data collected (related to gas composition and temperatures) has been used to validate the kinetic simulation model developed in Aspen Plus®. For this validation, a parametric study considering the factor that most affect the oxy-combustion process (the above mentioned excess amount of air ingress) was varied. The model was found to be in a very good agreement with the empirical results regarding the gas composition.

As propriedades físico-químicas da superfície de pós cerâmicos desempenham um papel muito importante na obtenção de produtos cerâmicos de alta qualidade, elevada performance e confiabilidade. Estas propriedades estão relacionadas com as ligações químicas superficiais e suas interações com o meio. As superfícies dos óxidos geralmente contêm grupos hidroxilas adsorvidos e as suas modificações podem ser estudadas por espectroscopia de infravermelho. Neste trabalho, pós à base de SnO2 contendo íons Fe ou Mg foram preparados pela rota química derivada do método de Pechini. Os pós foram caracterizados quanto à sua morfologia e suas propriedades superficiais. Os resultados obtidos mostraram que os aditivos segregam na superfície e modificam as bandas de infravermelho correspondentes aos grupos hidroxilas adsorvidas superficialmente. Estas modificações causaram mudanças em propriedades macroscópicas como o ponto isoelétrico das suspensões aquosas e a área de superfície específica dos pós. Os estudos quanto à sinterização destes materiais foram feitos com pastilhas conformadas por pressão uniaxial e foram submetidas à sinterização por queima rápida, apresentando densificação em tempos muito curtos de tratamento térmico. (<1 min.) Observações microestruturais mostraram que a redução da porosidade neste sistema ocorre congruente com crescimento de grãos. O aumento da área de superfície específica dos pós com a elevação da porcentagem molar dos aditivos, bem como a densificação rápida do óxido de estanho pode estar relacionada com a redução das energias de superfície quando os aditivos estão segregados na superfície dos grãos. / Surface properties of ceramic powders frequently play an important role in producing high-quality, high-performance, and reliable ceramic products. These properties are related to the surface bond types and interactions with the surroundings. Oxide surfaces generally contain adsorbed hydroxyl groups and modifications in the chemical composition of the surface may be studied by infrared spectroscopy. In this work, SnO2 containing Fe or Mg ions were prepared by organic chemical route derived from Pechini’s method. The prepared powders were characterized by means of surface properties and morphology. Results demonstrated that the studied additives segregate onto the oxide surface and modify the hydroxyl IR bands of the adsorbed hydroxyl groups. These surface modifications change some macroscopic properties of the powder such as the isoelectric point (IEP) in aqueous suspensions and the final specific surface area. The sintering behavior of these materials was studied using pellets conformed by uniaxial pressing and the sintering was made by fast firing, showing quick densification with shorts periods of time (<1 min.). A porosity reduction congruent with grain growth is observed during microestructure characterization. Both, increase of the surface area with additive concentration and quick densification are supposedly due to the reduction of surface energy of the powders when additives segregate on the powder surface.

How is information processed in the brain? This is one of the main and most challenging questions in Neuroscience. The established hypothesis is that information is encoded in the temporal dynamics of spikes. However, there is growing evidence that continuous signals such as Local Field Potentials (LFP) can play an important role in coding neural information. Recently, Montemurro et al. [2008] reported that the phase-of-firing code, a mechanism previously observed in the hippocampus, is used in the sensory cortices for information encoding. In the phase-of-firing code, the neurons communicate spikes with respect to the phase of continuous signals produced by population activity, such as the LFP. Using information-theoretic measures, it was shown that when the timing of spikes was measured with respect to the phase of the LFP, an extra amount of sensory information was revealed in the responses that was not available from the spike codes alone. On the one hand, it still remains to be established how widespread this novel coding mechanism is. So far it has been verified in a few sensory modalities and it is not clear whether it is a universal coding mechanism. On the other, the estimation of information from continuous signals poses serious challenges from a technical point of view. The main reason is that accurate estimations of information measures require unrealistic amount of experimental data, mostly due to the presence of correlated activity. When these measures are applied to assess the information content in continuous responses, they lead to severe biases in the results, which can affect the conclusions regarding the validity of specific neural codes. The main goal of this Thesis is to explore the universality of the phase-of-firing code by studying it in novel systems, establish the origin of this code, and to develop more effcient numerical methods to accurately quantify information encoded in continuous brain signals. In particular, in this Thesis we investigate the role of continuous signals in sensory modalities where it has not been explored so far. We verified the presence of a phase-of-firing code in both the somatosensory cortex of the rat, and the visual thalamus of mice, thus giving support to the possible universality of this coding mechanism. While the phase-of-firing code found in these systems shares common features with those found in previous studies, we also characterised important differences. In the rat whisker system it was found that high frequency bands of the LFP play a more prominent role than that observed in the visual and auditory cortices of monkeys. This is compatible with the behavioural and mechanical constraints of this system, which require a high discrimination of finely structured temporal information in the stimulus. In the case of the visual thalamus of mice, we found that the phase-of-firing code contributes significantly to the encoding of irradiance information conveyed by melanopsin photoreceptors in the retina. We also investigated the source of the phase-of-firing codes in cortex by modelling the relationship between population spikes and LFP. In particular, we studied the interplay between the effective spatial integration of information resulting from population activity and the temporal memory imprinted in the LFP as a consequence of filtering mechanisms in the neural tissue. We found that most of the information in the LFP comes from a neural neighbourhood of a radius of about 150-350 μm, and a temporal history of 200-300 msec. Finally, we developed novel practical methods for quantifying the information content of continuous signals in the brain, which yield accurate results under realistic experimental conditions. These methods are based on the projection of the statistics of the response space into a lower dimensional manifold. In particular, we modelled continuous neural responses as a hierarchy of Markov models of increasing order, and found that the structure of temporal dependencies of real LFP can be captured by the lowest orders. This helped us put a new light on the previous studies regarding the phase-of-firing code. Altogether, these results contribute an advance both at the level of understanding information coding strategies combining spike and continuous signals, and the required computational methods to quantify accurately information in experimental neural responses.

Suburban encroachment is a growing concern for many National Guard training installations. The Ethan Allen. Firing Range and Camp Johnson, Vermont, are either experiencing or are completely enclosed by urban encroachment. The objective of this study was to analyze the trends of suburban growth within Chittenden County, Vermont, to evaluate growth and explore future training site viability of the Ethan Allen Firing Range and Camp Johnson. This study focused on historical data, recent real estate transactions, population projections, and county plans for growth. Using historical and contemporary data, I developed a predictive model of suburban encroachment on Camp Johnson and the Ethan Allen firing Range facilities by residential and commercial development. This model may assist land managers make decisions and illustrate the viability of these installations as National Guard training sites. This model may also be applied to other installations with similar concerns.

In the electronics the quality, reliability, operational speed, device density and cost of circuits are fundamentally determined by carriers. If it is necessary to use better material than plastic carrier, it has to be made of ceramics or glass-ceramics. This study dealt with the ceramic based carrier production system. The types of the raw ceramics fired at low temperature (below 1000&deg / C) are called Low Temperature Co-Fired Ceramics (LTCC). In this study, a comprehensive thermal model is described for the high temperature oven which belongs to a Low Temperature Co-fired Ceramic (LTCC) substance production line. The model includes detailed energy balances with conduction, convection and radiation heat transfer mechanisms, view factor derivations for the radiative terms, thermocouple balances, heating filaments and cooling mechanisms for the system. Research was conducted mainly on process development and production conditions along with the system modeling of oven. Temperature control was made in high temperature co-firing oven. Radiation View Factors for substrate and thermocouples are determined. View factors between substrate and top-bottom-sides of the oven are calculated, and then inserted into the energy balances. The same arrangement was made for 3 thermocouples at the bottom of the oven. Combination of both expressions gave the final model. Modeling studies were held with energy balance simulations on MATLAB. Data analysis and DOE study were held with JMP Software.

Manure-based biomass (MBB) has the potential to be a source of green energy at large coal-fired power plants and on smaller-scale combustion systems at or near confined animal feeding operations. Although MBB is a low quality fuel with an inferior heat value compared to coal and other fossil fuels, the concentration of it at large animal feeding operations can make it a viable source of fuel. Mathematical models were developed to portray the economics of co-firing and reburning coal with MBB. A base case run of the co-fire model in which a 95:5 blend of coal to low-ash MBB was burned at an existing 300-MWe coal-fired power plant was found to have an overall net present cost of $22.6 million. The most significant cost that hindered the profitability of the co-fire project was the cost of operating gas boilers for biomass dryers that were required to reduce the MBB's moisture content before transportation and combustion. However, a higher dollar value on avoided nonrenewable CO2 emissions could overrule exorbitant costs of drying and transporting the MBB to power plants. A CO2 value of $17/metric ton was found to be enough for the MBB co-fire project to reach an economic break-even point. Reburning coal with MBB to reduce NOx emissions can theoretically be more profitable than a co-fire project, due to the value of avoided NOx emissions. However, the issue of finding enough suitable low-ash biomass becomes problematic for reburn systems since the reburn fuel must supply 10 to 25% of the power plant?s heat rate in order to achieve the desired NOx level. A NOx emission value over $2500/metric ton would justify installing a MBB reburn system. A base case run of a mathematical model describing a small-scale, on-the-farm MBB combustion system that can completely incinerate high-moisture (over 90%) manure biomass was developed and completed. If all of the energy or steam produced by the MBB combustion system were to bring revenue to the animal feeding operation either by avoided fueling costs or by sales, the conceptualized MBB combustion system has the potential to be a profitable venture.

Co-firing of biomass with coal in fluidized bed combustors is a promising alternative which leads to environmentally friendly use of coal by reducing emissions and provides utilization of biomass residues. Therefore, effect of biomass share on gaseous pollutant emissions from fluidized bed co-firing of various biomass fuels with high calorific value coals have extensively been investigated to date. However, effect of co-firing of olive residue, hazelnut shell and cotton residue with low calorific value lignites having high ash and sulfur contents has not been studied in bubbling fluidized bed combustors to date. In this thesis study, co-firing of typical Turkish lignite with olive residue, hazelnut shell and cotton residue in 0.3 MWt METU Atmospheric Bubbling Fluidized Bed Combustion (ABFBC) Test Rig was investigated in terms of combustion and emission performance and ash behavior of different fuel blends. The results reveal that co-firing of olive residue, hazelnut shell and cotton residue with lignite increases the combustion efficiency and freeboard temperatures compared to those of lignite firing with limestone addition only. O2 and CO2 emissions are not found sensitive to increase in olive residue, hazelnut shell and cotton residue share in fuel blend. Co-firing lowers SO2 emissions considerably while increasing CO emissions. Co-firing of olive residue and hazelnut shell has no significant influence on NO emissions, however, reduces N2O emissions. Co-firing cotton residue results in higher NO and N2O emissions. Regarding to major, minor and trace elements partitioning, co-firing lignite with biomasses under consideration shifts the partitioning of these elements from bottom ash to fly ash. No chlorine is detected in both EDX and XRD analyses of the ash deposits. In conclusion, olive residue, hazelnut shell and cotton residue can easily be co-fired with high ash and sulfur containing lignite without agglomeration and fouling problems.