The advantages of LPD method, low temperature process, low cost, conformal growth (good step coverage), selective growth and inexpensive deposition system make the method of LPD versatile in IC fabrication. LPD-SiOF is a potential method to replace traditional method of SiOF deposition. But, some drawbacks, including slightly low dielectric constant and poor performance of J-E relationship, still exist in LPD-SiOF process. In order to improve these shortcomings, with incorporating NH4OH into the LPD solution in this experiment, the SiOF:N film with high quality and low dielectric constant can be grown on Si by the TD-LPD method. In this study, the growth rate can be controlled well within 90~550 Å/h corresponding to the NH4OH concentration range of 0.1~0.8 M at the temperature range of 23~40 ¢XC. As TD-LPD-SiOF:N film deposited with 0.8 M NH4OH incorporation, the refractive index for can be kept at a constant 1.431 and the P-etch rate can be kept between 18.3 and 19.2 Å/s during the deposition temperature changes. The best experimental condition is found that incorporating 0.8 M NH4OH will get good results. If the concentration of 0.8 M is higher or lower than 0.8 M, the electrical characteristic will become poor. A model for TD-LPD-SiOF:N deposition mechanism is proposed. From the analysis of SIMS depth profile, the deposited film can be suggested that it is a combination of N-less LPD-SiOF film and N-rich accumulated interfacial layer. The properties of N-rich accumulated layer at the interface show the least effective oxide charges and lowest leakage current density. As the thickness of TD-LPD-SiOF:N film is 800 Å, the film has the best electrical characteristic. When the thickness is below or above 800 Å, all the properties become poor. TD-LPD-SiOF:N film deposited at 40 ¢XC with 0.8 M NH4OH incorporation with a thickness of 800 Å has the best physical, chemical, electrical properties. The F content for deposited film can reach 9.8 atom %. The dielectric constant can drop to about 3.07.

This work details the synthesis of low density porous polymers, and characterisation with an emphasis on Time Domain Nuclear Magnetic Resonance (TD-NMR). High energy laser physics utilises low density porous polymers to study astrophysical phenomena at high pressures and temperatures in the form of plasma. Low Z, low density Polymerised High Internal Phase Emulsions (PolyHIPE) and aerogels form a large part of these capabilities, however increasingly stringent laser target parameters are now required to develop new capabilities. For low density porous polymers, this demands greater control over properties such as pore size, density, composition (C[sub]nH[sub](>n)) and homogeneity through novel synthesis and characterisation. Microstructure inhomogeneity of styrene-co-divinyl benzene (S-co-DVB) polyHIPEs in conjunction with novel t-butyl styrene and para divinyl benzene polyHIPEs were investigated using ¹H spin-lattice (T₁) and spin-lock (T[sub](1ρ)) NMR relaxation experiments using TD-NMR. The strong relationship between ¹H spin-lattice relaxation times and Dynmaic Mechanical Analysis (DMA) data, and application of relaxation experiments at varied temperatures reveal that structural inhomogeneity is based on poor emulsion stability and clustering of DVB polymer affecting bulk molecular motion. Divinyl benzene (DVB) aerogels and a range of innovative C[sub]nH[sub](>n) aerogels such as poly-5-vinyl-2-norbornene were synthesised using free-radical, cationic or ring opening metathesis polymerisation techniques. A one-step synthesis of homogeneous density gradient DVB aerogels was developed for the first time, which is fundamental to be able to study plasma shock fronts. Characterisation using X-ray tomography revealed the homogeneous density gradient. Successful carbonisation of dichloroparaxylene (DCPX) aerogels has similar properties to resorcinol-formaldehyde (RF) aerogels, but is produced in significantly less time and shrinkage, presents as a candidate for future laser experiments. Correlation between NMR relaxation times to established techniques of DMA and mercury porosimetry was explored to determine the suitability of TD-NMR in characterisation of low density porous polymers.

[pt] Este trabalho considera o uso de um protocolo determinístico de acesso ao meio para transmissão eficiente de tráfegos assimétricos, através de um modo de operação TDD. Este modo é uma das opções selecionadas para adoção em sistemas celulares de terceira geração. São apresentados e analisados diferentes protocolos de acesso ao meio sendo um destes escolhido para ser implementado e ter o seu desempenho estudado. Diferentes modelos estatísticos para diversos tipos de tráfego assimétricos são considerados. Em seguida são discutidos os conceitos de qualidade de serviço (QoS) e os parâmetros que devem ser controlados.Continuando o trabalho são analisados detalhadamente: o protocolo escolhido, a maneira como este foi adaptado para aquele modo de operação e as medidas de desempenho que devem ser realizadas. Finalmente os resultados para cada tipo de tráfego individualmente e em conjunto são apresentados. / [en] This work has the objective of adapting a deterministic access protocol to the TDD mode of operation adopted as one of the third generation technologies in order to provide transmission of asymmetric traffic in a more efficient way. Different access methods are presented and analyzed and one of them is selected to be simulated and have its performance verified. Realistic asymmetric traffic models are discussed and actually implemented. Minimum requirements for Quality of Service for different traffics considered are introduced. The Quality of Service analysis made is focused on the minimum requirements of those traffic models. Detailed analysis of the chosen protocol is made in addition to its adaptation to the proposed situation. Finally, the results are presented showing the response of the protocol to each one of the traffic models considered and also to the situation when they are present simultaneously.

No description available.

In recent years, Eco-City, which is designed with consideration for environmental impact and is inhabited by people dedicated to minimisation of required inputs of energy, air pollution and water pollution, has emerged as a way to address sustainability issues by adapting it to their local needs and context. The sustainability of urban water resources, water recycling and more efficient use of water resources will be the key features of the Eco-City. The current study takes Sino-Singapore Tianjin Eco-City as an example to investigate the sustainable use of water resources which focus on non-traditional water usage and ecological water requirements assessment. Firstly, the potential non-traditional water supply was evaluated based on the data acquired from the gauging station and the Eco-City planning data. It was found that rainwater has a great potential for domestic use in the Eco-City from June to September. Differing from other water consumption, ecological demand of the river lake system in the Eco-City was analysed by minimum ecological water requirements determination. An improved wetted perimeter method was used in order to determine the minimum ecological water requirements in the river system. It was found that the current monthly flow rates, with the exception of January to March, are fairly satisfactory. Secondly, an idealised river-lake system was assessed by hydraulics laboratory experimentation and 2D numerical modelling. The experimental and numerical investigations described in this study were undertaken to improve understanding of the hydrdynamic and flushing process within such a river lake system. A water diversion scheme was implemented in order to study lake recharge by river water during dry periods and under augmented flows. Fluorescent tracer experiments and related computer simulations were conducted to assess the performance of different parts of the system before and after implementing the diversion scheme. The results showed that such measures improved flushing, as seen from the perspective of reducing the mean detention time. However, due to poor cross-sectional velocity distribution, recharge alone had little impact on the overall mixing level in the lake waters. The effect of inserting flow deflectors near the lake inlet combined with flow augmentation was then assessed and was found to positively affect the distribution of solutes, by mitigating the occurrence of dead zones. Finally, an eco-hydraulic model was used to determine the levels of fish habitat suitability in the fluvial and lacustrine regions of a new Eco-City. This model has been developed by combining a depth integrated hydrodynamic and water quality model with a Habitat Suitability Index model. Carps were selected as the target species as they represent the major fish population in the study area. Hydrologic data recorded during 2001-2010 were analysed to determine the base flow, average flow and high flow rates, which were used to represent the discharges in the river for the three stages of the carp life cycle: overwintering, spawning and growth, respectively. Numerical model simulations were undertaken to determine the levels of habitat suitability for carps to live at these three life stages. The model results indicated that under the current flow regime the habitat suitability level in the lacustrine region is too low for carps at the growth and overwintering stages. DO depletion, overriding the role of velocity and depth, was attributed to the poorly suited habitat conditions in the lacustrine region. To improve the suitability conditions in the lacustrine region, a DO enhancement scheme was used. Model results showed that the scheme has significantly enhanced the water quality in the lacustrine region. Due to the high flow requirement for carps to spawn in the fluvial region, further numerical model simulations were undertaken to investigate the effect of flow augmentation on the carp spawning habitat suitability.

The huge amount of petroleum hydrocarbons contaminated sites is the heritage of a long history of fossil fuels usage. Reducing petroleum hydrocarbons levels in contaminated soils by Fenton reaction and with the aid of one or two agents such as solvents, surfactants, or vegetable oils has been studied in recent years, with successful reported results. Nonetheless, destruction of the aliphatic fraction of total petroleum hydrocarbon (TPH) by Fenton reaction has been studied to a lesser extent as compared to the aromatic fraction of TPH. Additionally, studies regarding the effect of humic acid (HA) on Fenton reaction reported contradictory results, and more research is necessary to clarify HA effects. Lastly, although achieving the highest efficiency is the main objective of soil remediation technologies, the environmental side effects of the applied processes should be considered as important as the efficiency. In light of these, the main aim of this project was to increase Fenton treatment efficiency by using an environmental friendly solvent, ethyl lactate (EL). The project objectives included determining optimum levels for the reagents of Fenton reaction and desorption process such as hydrogen peroxide (H2O2) and EL, identifying the kinetic of TPH desorption and destruction of petroleum hydrocarbons by Fenton reaction in addition to analysing the effects of EL on these processes. Through desorption tests, EL/water solution demonstrated great ability to increase the removal efficiency and desorption of sorbed TPH. Desorption by EL/water solution consisted of a very fast desorption stage followed by a slow stage. After 30 min of desorption, the removal efficiency of TPH increased from 63% to 81% for EL=25% and EL=100%, respectively. The initial desorption rate for 25% and 100% were 1.625 mg/min and 3.368 mg/min, respectively. The results of batch experiments indicated that EL%=10% was the optimum value for the EL-modified Fenton reaction. After 4 h, an increase in H2O2 concentration from 0.1 M to 2 M at L/S=2 and EL=25% increased the removal efficiency of TPH from 68.41% to 90.21%. HA addition up to 150 mg/l was also studied. For fraction 1, adding HA led to an increase in removal efficiency while for fraction 2, only HA=150mg/l had higher removal efficiency than the HA=0 case and for fraction 3, addition of HA in the studied range could not increase the removal efficiency. A good compatibility of zero-valent iron nanomaterial with H2O2 was proved. Laboratory column experiments were finally carried out to remove petroleum hydrocarbons from diesel-contaminated soil with EL to reproduce the conditions of in-situ treatment. The remaining diesel in soil decreased by increasing H2O2 molarity from 0.1 M to 0.5 M whereas a further increase to 2 M led to an increase in remaining diesel in soil. The stability of H2O2 in EL has been observed which signifies good potential for in-situ applications. Overall, the project has demonstrated the feasibility of EL-modified Fenton reaction for the remediation of petroleum-contaminated soil.

The debates and discussions (discourses) surrounding shale gas in the United Kingdom (UK) far outstrip any physical development of the potential energy source. The UK sits on a significant potential resource of 1329tcf. (Andrews, 2013) of shale gas, yet there are increasingly polarised positions on whether this resource should be developed. On the one hand, proponents of its development point to the United States (US) and the significant economic impact the rapid expansion of shale gas development has had. On the other, concerns are raised about the purported negative environmental impacts shale gas development may have, particularly questions about its climatic impact and the contamination of water. The polarisation of UK shale gas discourses made it impossible to conceive that proponents of each 'side' were not viewing the same version of shale gas; the differences were simply too great. An alternative research framework is therefore developed within this thesis. An approach which does not impose pre-emptive boundaries on the discourses, with the binary understandings of 'pro' or 'anti' and the thematic categorisation of content being done away with and tossed onto the bonfire. The approach draws on Actor-Network Theory (ANT) which treats shale gas discourses as actor-networks within which the content of discourse, such as water contamination, are considered actors. These actor-networks are traced to explore the form and formation of UK shale gas discourses, and ultimately why some discourses become salient, whilst others fail. Given the disconnect between different positions on shale gas, Mol's (1999 & 2002) work on multiple realities was incorporated to argue that rather than there being multiple perspectives on shale gas, there are rather "more than one, less than many" (Mol, 2002) versions, or realities, of shale gas. This research draws on 83 semi-structured interviews with a variety of stakeholders interested in the emergence of UK shale gas and were conducted between 2013 and 2014. By following these stakeholders as they lay out their realities of shale gas through actor-networks of discourses, this research explores which actors stakeholders mobilise within their discourses, and how they are performed through the alignment and translation of the actors to produce effect - shale gas discourses. This, enabled a nuanced insight into UK shale gas discourses from those mobilising them. In doing so, this research highlighted several key aspects of UK shale gas discourses. First and foremost was the dominance of water discourses. This was due to water contamination as a result of shale gas development being seen as a foregone conclusion by stakeholders, as a result of it becoming a punctualised actor, whereby water contamination was reduced to end effect. The explanations of how or why it may occur being successfully masked within the actor-networks. The research also highlighted the reason for this dominance being in no small part to the spatial aspects of the US experience of shale gas development being imported without spatial-context to the UK. The way stakeholders performed UK shale gas discourses was also a significant finding, specifically that discourses were a system of alliances with multiple actors mobilised in support of a broader discourse, as opposed to a structured thematic consideration of the issues. Finally, the incorporation of multiple realities led to the conclusion that the negativity of shale gas has become a 'matter of fact', with a dominant more-negative reality transcending all others to a lesser or greater-degree and influencing discourses of shale gas with negative translations. Overall, this research speaks to the small but growing literature on UK shale gas discourses. The development and employment of an alternative research framework based on ANT and multiple realities may have wider applications both for exploring UK shale gas discourses in greater depth, but also for considering other controversies.

Carbon capture and storage (CCS) is considered to be one of the strategically important carbon abatement technologies that can be used to effectively reduce the carbon emissions from fossil fuel power plants and other large scale industrial processes, which are the major stationary sources of greenhouse carbon emissions. Compared to other capture technologies, solid adsorbents looping technology (SALT) based post-combustion carbon capture, an alternative to the state-of-the-art energy intensive amine scrubbing process, is widely viewed as being the most viable technology that can be used as either as a retrofit to existing power plants or new build capacity. The potential success of SALT technology is largely determined by the development of novel CO2 adsorbents. Amine immobilized solid adsorbents are highlighted to be used in SALT technology due to their high CO2 selectivity (CO2/N2 >1000), suitable adsorption temperature and tolerance of moisture. Although they have so much advantages on carbon capture, the oxidation and degradation of solid amines are still a significant problem to be overcome. The degradation of the amine adsorbent can lead to a reduction in CO2 capture performance and selectivity, an increase in the process cost and corrosion problems. The aim of this project is to 1) develop new solid adsorbent materials with higher CO2 capture ability and superior adsorption-desorption lifetime performance; 2) to investigate effective measures to minimise or effectively prevent the thermal and oxidative degradation of the sorbent materials; 3) to explore approaches that can rejuvenate the degraded sorbents for re-use or convert them into other value-added products. Firstly, a series of PEI-the porous siliceous cellular foams (SCF) adsorbents have been developed and characterised. The results show a relationship between the textural properties of SCF and CO2 adsorption ability of adsorbents. A highly effective hydrothermal methodology was developed to produce extremely mesoporous silica materials with well-defined mesoporous structures and greatly increased pore volumes of up to 3.2 cm3/g. The PEI adsorbents prepared using SCF-3-120-24 (1.6 cm3/g) was found to have CO2 capture capacities of nearly 180.8 mg/g, which represents the highest adsorption capacity ever reported for supported PEI adsorbents. Secondly, lifetime performance testing and strategies to mitigate the thermal-oxidative degradation of PEI adsorbents and rejuvenation of the degraded PEI was investigated. The presence of moisture and additives was seen to enhance the thermal-oxidative stability of PEI. Furthermore, the doping of Na2B4O7 hydrates can increase the cyclic adsorption-desorption lifetime performance of PEI adsorbent. Meanwhile, the CO2 adsorption capacity of one heavily degraded PEI adsorbent was increased from 2.8 wt% to 6.2 wt% after rejuvenation test. Finally, hydrous pyrolysis and a continuous flow reactor system was used in catalytic hydrotreatments and hydrothermal treatments of six model MEA degradation compounds and two degraded MEA solvents. Most of the model compounds and degraded MEA was converted to piperazine derivatives in a H2 reaction atmosphere and pyrazine derivatives in NH3 reaction atmosphere. Piperazines and pyrazines are a type of important pharmaceutical intermediates.

The work in this thesis focuses on the synthesis of metal organic frameworks (MOFs) both in batch and continuous work. Improvements are made in both, compared to the previous research. Furthermore, post-modification experiments are conducted to advance the characteristics of end product. Also, their application as solid sorbents in carbon capture is investigated. In Chapter 1, the background of greenhouse gas emissions is reviewed and discussed, followed by the development of carbon capture technologies and different adsorbents used in post-combustion carbon capture. An introduction to metal organic frameworks is then presented, including a literature review of the research to date, and various synthesis methods including batch and continuous routes. The last part of this chapter presents a literature review on how pre-synthetic design and post-synthetic modification synthesis of MOFs can be achieved. The theories and introductions of the characterization techniques used in this thesis are discussed in detail in Chapter 2. Chapter 3 discusses a new batch method for the efficient synthesis of micro-sized HKUST-1 with high yield (84%) under mild conditions. Different activation methods are conducted in the washing process. Both ethanol and methanol are tested to remove the impurities in pores of the samples. Finally, the optimal sample of HKUST-1 achieved is shown to produce a relatively high surface area (1615 m2/g) with a CO2 adsorption of 8.1% (measured by TGA at 1 atm and 27 oC). A step increase in the surface area is made by immersing the powders into a solution consisting of NaCl, water and methanol. Nano scale HKUST-1 is synthesized by adding trimethylamine (TEA) solution with the organic ligand precursor. The reaction rate is accelerated with this case because TEA solution is able to deprotonate the trimesic acid (the organic ligand). The method for nano scale HKUST-1 synthesis is the focus of Chapter 4. Chapter 5 reports the continuous synthesis process of HKUST-1 and ZIF-8. This work builds on previous work at Nottingham. A counter-current Nozzle reactor is used in this work. The products were compared with commercial equivalents. Post-synthetic modification of HKUST-1 was made to improve the hydrophobicity of HKUST-1 to extend its resilience to breakdown in the presence of moisture. In Chapter 6, a hybrid material TiO2@ZIF-8 is synthesized using the same reactor. Different reactor configurations were also used to generate a range of different products that are then compared. To conclude, a summary of the work conducted in this thesis is presented in Chapter 7, followed by a discussion on potential future work.

Accelerated carbonation technology (ACT) could be used for the stabilisation of hazardous wastes, remediation of contaminated soils and re-use/recycling of various waste streams. ACT has also potential for storing anthropogenic CO2 emissions into mineral silicates and alkaline waste residues via mineral or waste carbonation. Compared to ocean and geological storage, mineral and waste carbonation offer several advantages such as long-term storage and low monitoring requirements. Currently, the biggest challenge of mineral carbonation is the low conversion rate of calcium and magnesium-based minerals into thermodynamically stable carbonates under ambient temperature and pressure. Also, literature offers little information about physical techniques or chemical substances that could enhance the efficacy of accelerated carbonation of alkaline wastes. In this study, various carbonation techniques were applied for increasing the carbonation reactivity of magnesium hydroxide. The experiments were conducted under low temperature and pressure, while the maximum reaction time was 24 hours. Under these conditions the associated costs are kept to a minimum. The possibility of producing monolithic products with value-added was investigated by using blended mixtures of magnesium and calcium hydroxide. These mixtures were cured in carbon dioxide for 7 and 28 days and their physical properties were measured and compared with the properties for normal and lightweight concrete. Moreover, several alkaline residues were carbonated with the aid of ultrasound and four candidate catalysts (acetic acid, ethanol, sodium hypochlorite and sodium nitrite) and their CO2 uptake was measured. During sonication the variables: ultrasonic frequency, water content and treatment time were examined, while the applied chemicals were added at three different molarities (0.1 M, 0.5M and 2.5M). Throughout this work a number of analytical techniques were used for the characterisation of the raw and carbonated materials. These techniques included XRay fluorescence, X-ray diffraction, wet laser analysis, total organic carbon analysis and scanning electron microscopy. The results showed that the CO2-reactivity of Mg(OH)2 was low due to thermodynamic constraints that inhibited the rapid diffusion of CO2 into the system. The mixtures composed of pure Mg showed improved compressive strength and bulk density. In addition, sonication at low water content was weak, as there was lack of enough water to facilitate cavitation. On the other hand, at high water content the achieved CO2 uptake of the products increased by up to four times, as the wet conditions enhanced the cavitation of the solid particles. Finally, it was found that ethanol and acetic acid promoted the hydration rate of CO2 during accelerated carbonation, while minerals phase analysis did not reveal the formation of toxic by-products. In conclusion, the findings of this study proved that sonication depends highly on water content and is favoured at wet conditions. Furthermore, acetic acid and ethanol are two chemicals with potential to ameliorate the accelerated carbonation of various industrial wastes without the formation of un-desired or toxic compounds.