Previous studies found large biases between individual observational and model estimates of historical ocean anthropogenic carbon uptake. We show that the largest bias between the Coupled Model Intercomparison Project phase 5 (CMIP5) ensemble mean and between two observational estimates of ocean anthropogenic carbon is due to a difference in start date. After adjusting the CMIP5 and observational estimates to the 1791-1995 period, all three carbon uptake estimates agree to within 3Pg of C, about 4% of the total. The CMIP5 ensemble mean spatial bias compared to the observations is generally smaller than the observational error, apart from a negative bias in the Southern Ocean and a positive bias in the Southern Indian and Pacific Oceans compensating each other in the global mean. This dipole pattern is likely due to an equatorward and weak bias in the position of Southern Hemisphere westerlies and lack of mode and intermediate water ventilation.

Memoria para optar al Título Profesional de Ingeniero Forestal

Holding approximately 89,000 Tg of organic carbon, tropical peatlands are one of the largest pedological sinks of carbon (Page et al., 2011). Waterlogged conditions in undisturbed peatlands reduce heterotrophic respiration and provide environments in which organic matter accumulates (Moore et al., 2013). However, from 1990 to 2010, the forest cover in the peatlands of South East Asia fell from 77% to 36%; at this rate of decline, all of the undisturbed peatlands are likely to have disappeared by 2030 (Li et al., 2007; Koh et al., 2011; Miettinen et al., 2011). Land-use changes in these ecosystems can have important consequences for carbon (C) budgets (Page et al., 2002; Hooijer et al., 2010). Recently a number of studies have been carried out on tropical peatlands (e.g. Couwenberg et al., 2010; Hergoualc'h and Verchot, 2011; Hirano et al., 2012; Jauhiainen et al., 2005, 2012; Li et al., 2007; Melling et al., 2005; Page et al., 2009), but some parts of the C budget are yet to be quantified. In order to fill these gaps in our knowledge, the goal of this work was to assess heterotrophic and total soil respiration, litterfall, litter decomposition and evaluate peat properties in an intact peat swamp forest, a transitional logged drained forest and an oil palm plantation located on the same alluvial peat plain. This in-situ research lasted two years, and heterotrophic and total soil respiration were separated using the trenching method. Our results from the carbon dioxide flux monitoring in the three land uses showed that the trenched plots provided a good proxy for heterotrophic respiration. The annual integrated total soil respiration was lower in the intact and drained forest than in the oil palm plantation, at 20.2 ±3.4, 18.7 ±1.1 and 26.4 ±1.7 Mg C ha-1 y-1, respectively. A similar pattern was seen in the heterotrophic respiration for the same land uses, 9.6 ±7.7, 15.7 ±1.0 and 22.9 ±2.0 Mg C ha-1 y-1, respectively. When extrapolated to the landscape, the percentage of heterotrophic 4 respiration appeared to have significantly increased following drainage, even before the conversion to oil palm, with percentages of 47.6 ±10.1, 83.9 ±7.3, 86.6 ±1.9 for intact forest, drained forest and oil palm plantation, respectively. The average litterfall in the three land uses was not significantly different, at 26.3 ±4.1, 23.2 ±4.2 and 18.6 ±3.5 kg dry litter ha-1 d-1 respectively. Overall, the C fluxes results produced in this thesis point towards a negative C balance (i.e. net ecosystem loss of C) for the drained forest, a pronounced negative C balance for the oil palm plantation and a near neutral balance for the intact forest. Other relevant findings in the study were: (1) the impacts of N fertilizer application in the oil palm plantation lasted only a few days and were unlikely to have significant consequences on the annual C budget; (2) concerns over the diurnal variability of carbon dioxide fluxes are not particularly pertinent in these tropical peatlands; and (3) the principal soil property affected by drainage and land-use change was the abundance of logs in the soil. In summary, the results produced in this thesis represent noteworthy data about the C budget and C dynamics in tropical peatlands and will help decision making by policy makers and land managers for sustainable use of these ecosystems.

Although the environmental imperative compels us to search for a low carbon system of mobility, contemporary society seemingly necessitates a low carbon automobility. The costs and impracticalities of low carbon vehicles are well documented, and although the cultural and semiotic nature of the car means that it has always been more than just a means of transport, less is known about how socio-cultural mores regarding the car might impact upon the transition to low carbon motoring. Because cars carry people, then they inevitably carry experiences and meanings too. However, a shift from conventional internal combustion-engined vehicles to more low carbon forms of propulsion, such as electric or hybrid vehicles, suggests that the nature – et ergo our experiences and perceptions – of the car will necessarily change. It is therefore desirable to investigate the contemporary ‘consumption’ of the car, not only as personal transport but also as status symbol, cultural artefact and experience, to assess how such a socio-cultural consumption might apply to low carbon vehicles and so ascertain the subsequent potential for a holistic low carbon automobility as part of a sustainable transport policy. A suite of methods was employed to investigate if or how contemporary automobilities can aspire to a low carbon automobility, or whether the everyday socio-cultural ‘consumption’ of the car might preclude a transition to low carbon vehicles. The notions of affect and/or non-representational theory were appropriated as a philosophical framework to look beyond a seemingly default postmodern ‘car-as-representation’ approach to the consumption of the car and so begin to explore a deeper, perhaps even subconscious, regard for the car. In addition, opinion was sought from stakeholders within the low carbon vehicle sector as to the technologies within, the prospects for, and the efficacy of, UK low carbon vehicle policy and its facilitation thereon, and also with a sample of EV drivers as to their experiences of electric cars. Responses to an initial online questionnaire appeared to deny any status or regard for the car beyond its utility. However, subsequent semi-structured interviews with motorists conducted (mostly) in their cars contradicted these findings, with a variety of expressed feelings – pride, empowerment, fortune – suggesting a deeper, subconscious regard for, reading of, and connection with, the car than is immediately apparent. Similarly, the utility of the electric car was transcended, this time by feelings of ‘greenness’ and ‘calm’ expressed by EV drivers. A stated amenability and aspiration by those interviewed for low carbon vehicles contrasted with an aspiration for sporty and prestige cars, suggesting an ingrained or innate idea as to what constitutes a truly desirable car. The more cultural facets of the car explored during focus group discussions established a connection between a car’s cultural representation and its meaning. Interviews with low carbon vehicle stakeholders suggest that while UK low carbon vehicle policy is broadly effective, is not as efficacious as it could be, in that itinerate market-led aspirations lack the fixity and certainty, in terms of both infrastructure and policy, that investors and consumers require, especially given a high entry price, the promise of lower running costs notwithstanding. In establishing where ‘here’ is regarding the consumption of the car and the implementation of a low carbon vehicle policy, this research provides a new perspective upon the appetite and potential for a transition to a future low carbon automobility, and shows the efficacy of appropriating the notions of affect and non-representational theory to a more holistic consumption of the car.

Ph.D. (Chemistry) / Please refer to full text to view abstract

The interfacial micromechanics of both high modulus and low modulus carbon fibres have been investigated using Raman spectroscopy. The innovative step was to make low modulus carbon fibres more Raman active by coating them with SWNTs to act as as a strain sensor. Two types of SWNTs have been employed; namely HiPCO SWNTs and COOH SWNTs. Single fibre deformation tests were carried out and the Raman band shift rates with respect to fibre strain have been determined. Meanwhile, different SWNTs coating methods have been investigated. The method of adding COOH SWNTs into the silane layer and within a hot cured epoxy layer was found to generate the highest band shift rates. Furthermore, an investigation of the effect of SWNTs on the strength of the interface was also carried out. A coating of COOH SWNTs was found to significantly improve the interfacial shear strength. Micromechanical tests have been carried out and the stress transfer between the carbon fibres and an epoxy resin was monitored using three different model composite geometries; namely microdroplet-fibre, a film-fibre and a standard fragmentation approach. The result of interfacial shear stress determined from microdroplet-fibre method varied and was found to be highly dependent on the droplet size and shape; this gave the lowest values of interfacial shear stress (ISS). The method of film-fibre obtained an intermediate ISS value which is between that from the microdroplet model test and the fragmentation test. The standard fragmentation test using Raman technique gives the highest ISS and HiPCO SWNTs were found to be a better strain sensor without affecting the original interfacial properties.

Ph.D. (Chemistry) / In this study, carbon based electrode materials such as glassy carbon, graphene, diamond and exfoliated graphite were explored as suitable electrode materials for electrochemical detection, electrochemical and photoelectrochemical degradation of organic water pollutants. Graphene modified glassy carbon electrode sensor was developed for bisphenol A. Cyclic voltammetry was used to study the electrochemical properties of the prepared graphene- modified glassy carbon electrode using potassium ferricyanide as a redox probe. The prepared graphene- modified glassy carbon electrode exhibited more facile electron kinetics and enhanced current of about 75% when compared to the unmodified glassy carbon electrode...

Carbonaceous materials, especially in micro and nanoscale, are useful in optical, energy storage, electronic, and biomedical devices or technologies. Techniques have been developed for preparation and modification of the carbonaceous materials, while it is still challenging to tailor the properties of carbonaceous materials effectively and economically. Laser is a powerful tool in academic and industrial laboratories, which also plays important roles in the preparation and modification of high-performance carbonaceous nanomaterials. In this study low-cost hydrothermal synthesis, high-temperature annealing, and Laser ablation (LAL) methods are developed to prepare functionalized carbon nanomaterials and modify their electrochemical and optical properties. Sub-micro hollow carbon spheres are synthesized via hydrothermal carbonization and high-temperature activation without any templates. Good capacitive properties are obtained after activation. The electrochemical properties of the activated carbon spheres depend on the media of the activation. The capacitance of the activated carbon spheres significantly increases with the addition of water as an activation agent. Carbon dots (CDs) are synthesized via a facile and economic hydrothermal (HTC) process using both small-molecule sugar (Xylose) and ground soybean residuals as precursors. The photoluminescence (PL) properties of the as-prepared and further-treated CDs are systematically studied. For the xylose-synthesized CDs, the initial green PL emission disappears after high-temperature treatment at 850 ℃ for 2 h. With further LAL treatment in NH4OH solutions, the PL emission is re-acquired, and a blue shift in emission is observed. Thus, the LAL is found to be an effective method to modify the CDs and their PL properties. For the nitrogen-doped soybean waste-derived carbon particles, they show strong blue emissions, which essentially disappear after 850 ℃ annealing for 2 hours in an argon flow. Then, PL appears again after laser ablation in a 10% NH4OH solution. The conversion from the blue emission to no emission and then back to blue emission again implies the effect of the functional groups on the PL properties of the CDs.

京都大学 / 新制・課程博士 / 博士(工学) / 甲第23389号 / 工博第4881号 / 新制||工||1763(附属図書館) / 京都大学大学院工学研究科分子工学専攻 / (主査)教授 田中 庸裕, 教授 今堀 博, 教授 佐藤 徹 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

AN ABSTRACT OF THE THESIS OFChristoph Michael Goettler, for the Master of Science degree in Mechanical Engineering, presented on Nov 6, 2020, at Southern Illinois University Carbondale. TITLE: EFFECT OF DENSITY ON FRICTION AND WEAR PERFORMANCE OF CARBON-CARBON COMPOSITE MATERIALSMAJOR PROFESSOR: Dr. Peter FilipCarbon-carbon (C/C) composite materials exhibit high thermal conductivity, high thermal stability, low density, and high mechanical strength. Due to these properties, C/C composites are ideal for use in high performance braking systems. However, C/C composites are incredibly expensive to manufacture, and thus improving the longevity of these materials is vital. C/C composite materials inherently have a density gradient due to manufacturing limitations. By determining the effect of density on friction and wear performance of C/C composite materials, manufacturers could use that data to alter manufacturing methods to improve the lifespan of C/C composites. In this study, the effect of density on friction and wear performance of C/C composite materials was studied. Friction tests were conducted through use of a universal mechanical tester (UMT) manufactured by Bruker and subsequent analysis was done through use of scanning electron microscopy, energy dispersive x-ray spectroscopy, and polarized light microscopy. Numerous samples from depths of 0 mm and 5 mm were taken from two C/C composite materials with varying matrices and friction tested at varying conditions to determine friction properties, friction surface characteristics, microstructure just below the friction surface characteristics, friction layer characteristics, and wear characteristics. Density, apparent density, and apparent porosity gradients were also measured to be able to correlate observations to density differences. It was observed that while density does not seem to be the main cause in differences in friction and wear performance of C/C materials at depths of 0 mm and 5 mm, there still existed significant differences in friction performance, wear performance, and post friction test material characteristics when comparing 0 mm samples to 5 mm samples. In conclusion, density was not found to be a significant cause in variations in friction performance. However, friction surface depth was found to have a significant effect on friction performance, wear performance, and the friction surface. Further research is needed to be able to determine the exact cause of the variations in performance at depths of 0 mm and 5 mm. Keywords: carbon-carbon, composite, C/C, density, friction, wear, brake