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The land (or ‘terrestrial’) biosphere strongly influences the exchange of carbon, energy and water between the land surface and the atmosphere. The size of the land carbon store and the magnitude of the interannual variability of the carbon exchange make models of the land surface a vital component in climate models. This thesis addresses two aspects of land surface modelling: soil respiration and phenology modelling, using different techniques with the goal of improving model representation of land-atmosphere interaction. The release of heat associated with soil respiration is neglected in the vast majority of large-scale models but may be critically important under certain circumstances. In this thesis, the effect of this heat release is considered in two ways. Firstly, a deliberately simple model for soil temperature and soil carbon, including biological heating, is constructed to investigate the effect of thermal energy generated by microbial respiration on soil temperature and soil carbon stocks, specifically in organic soils. Secondly, the mechanism for biological self-heating is implemented in the Joint UK Land Environment Simulator (JULES), in order to investigate the impacts of the extra feedback in a complex model. With the intention of improving estimates of the parameters governing modelled land surface processes, a data assimilation system based on the JULES land surface model is presented. The ADJULES data assimilation system uses information from the derivative of JULES (or adjoint) to search for a locally optimum parameter set by calibrating against observations. In this thesis, ADJULES is used with satellite-derived vegetation indices to improve the modelling of phenology in JULES.

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Ce travail porte sur la fabrication d’un support inorganique de nanofils de silicium dédié à la détection sensible de biomolécules par désorption/ionisation laser (LDI) en spectrométrie de masse (MS). Cette technique, contrairement à l’analyse LDI assistée par matrice (MALDI), permet de s’affranchir des ions parasites de la matrice organique qui interfèrent avec les molécules de masses inférieures à 700 Da. La littérature fait état de la difficulté à déterminer les paramètres liés à la performance de la technique : nous avons varié la morphologie, la composition, la chimie de surface des nanofils de silicium et nous avons discuté de l’importance des propriétés optiques et thermiques, de la mouillabilité de surface et de l’accessibilité des molécules au faisceau laser. Le support de nanofils optimal montre une haute sensibilité de détection des molécules de petites masses (50 fois supérieure au MALDI), il s’adapte à des analyses protéomiques et nous a permis d’instaurer un contrôle complémentaire au suivi de la réaction de méthylation pour la conception d’une biopuce à peptides. Nous avons finalement travaillé sur l’intégration de ce support dans un laboratoire sur puce. Une goutte d’1 µL d’un mélange de peptide (50.10-15M) a été déplacée par microfluidique discrète (électromouillage sur diélectrique) puis analysée avec succès par LDIMS. Finalement, nous avons développé une méthode originale combinant la chimie et la topographie de surface des nanofils de silicium à des techniques de lithographie optique : des zones de différentes tensions de surface liquide/solide sont ainsi créées et sont favorables à l’adhésion localisée de protéines, de cellules et de bactéries. / This work deals with the fabrication of an inorganic silicon nanowires substrate dedicated to the sensitive detection of biomolecules by laser desorption/ionisation mass spectrometry (LDI-MS). This technique, in contrast to the matrix-assisted LDI mass spectrometry (MALDI), allows low mass molecules’ (<700Da) analysis without parasitic peaks from the organic matrix. The literature reports the difficulty to determine the parameters linked to the technique’s performance. We varied the morphology, composition and surface chemistry of silicon nanowires, and discussed the importance of optical and thermal properties, wetting properties and accessibility of analytes to the laser beam on the silicon nanowires performance. The optimized nanowire’s substrate shows a high sensitivity for the detection of low mass molecules (50 times higher than classical MALDI). Moreover, the silicon nanowires substrate was successfully used to follow the course of the methylation reaction of peptides in a biochip format. Furthermore, the substrate integration in a lab on chip was investigated. A 1 µL droplet of a peptide mixture (50.10-15M) was displaced by digital microfluidics (electrowetting on dielectric) and successfully analyzed by LDI-MS. Finally, we developed an original method combining the chemistry and topography of silicon nanowires surface using optical lithography technique: areas with different liquid/solid surface tensions are created this way, enabling localized adhesion of proteins, cells and bacteria.

The demands placed on back-up rolls in hot strip mills have been investigated by a combination of literature and industrial studies. The tribological operating conditions have been established and the maximum local loads and pressure distributions at the work roll/back-up roll interface have been obtained by processing mill and roll schedule data using a computer program (commercial software developed by V AI Industries (UK) Ltd) and applying the theories of contact mechanics. After a study of the responses of the rolls to these demands and possible failure mechanisms, research has centred on surface initiated damage whereby cracks can propagate into the roll substrate potentially reaching the internal residual stress fields and leading to catastrophic failure. A proposed qualitative contact and fracture mechanics model, for the rolling contact fatigue and spalling failure, has been quantified theoretically using published methods for determining the stress intensity factors at the tips of pressurised and water lubricated, inclined rolling contact fatigue cracks. The predictions of the quantitative model in terms of crack directions and lengths have been validated by microscopic observation of the morphologies cracks produced in test discs used in the "SUROS" Rolling-Sliding Testing Machine and also in a sample of material spalled from a back-up roll. The quantitative failure model includes criteria for crack branching either upwards leading to micro spalling or downwards (potentially catastrophic) and the link between these two cases has been related quantitatively to the value of the mode I threshold for the roll material. After linking mechanics to microstructure and quantifying the interactions between wear and rolling contact fatigue in this case, practical quantitative recommendations have been made for the design of bainitic back-up roll materials, back-up roll redressing procedures and the surface roughness of both the work rolls and back-up rolls presented to the mill.

Effect of surface treatments on Strength and durability of aluminum 6061-Henkel Hysol EA 9891RP (room temperature curing epoxy) bond was studied using single lap shear, flatwise tensile and wedge crack test. The interfacial strength (IFSS) and % cohesive fracture varied with composite adhesive thickness and 0.03-0.04 mm that maximized the interfacial fracture was chosen to compare surface treatments. The effect of treatments on IFSS and tensile strength increased in the following order: PAA+BR127 (RT) < UT+BR127 (120oC) < Alodine < Alodine+EC3901(RT) < Alodine+BR127 (RT) < PAA < UT < UT+BR127 (RT) < Alodine+EC3901 (90oC) < PAA+EC3901(RT) < PAA+EC3901(90oC) < PAA+BR127 (120oC) < UT+EC3901(90oC) < UT+EC3901(RT) < Alodine+BR127 (120oC). The environmental durability decreased in the following order Alodine+EC3901 (90oC) < Alodine+BR127 (120oC) < PAA+BR127 (120oC) < PAA+EC3901 (90oC) < UT < UT+EC3901 (90oC) < UT+EC3901 (RT) < PAA+EC3901 (RT). PAA and Alodine, combined with BR127 (120 oC) and EC3901 (90oC) are the optimal surface treatments / October 2016

It is said that a topologist is a mathematician who can not tell the difference between a doughnut and a coffee cup. The surfaces of the two objects, viewed as topological spaces, are homeomorphic to each other, which is to say that they are topologically equivalent. In this thesis, we acknowledge some of the most well-known examples of surfaces: the sphere, the torus, and the projective plane. We then observe that all surfaces are, in fact, homeomorphic to either the sphere, the torus, a connected sum of tori, a projective plane, or a connected sum of projective planes. Finally, we delve into algebraic topology to determine that the aforementioned surfaces are not homeomorphic to one another, and thus we can place each surface into exactly one of these equivalence classes.

Master of Science / Department of Industrial & Manufacturing Systems Engineering / Shuting Lei / Malgorzata Rys / The demand of synthetic implants for good quality of life is high and increasing continuously due to limitations of autogenous bone grafting. Development of various synthetic bio materials and their manufacturing methods in the fields of orthopedics and dentistry has been done and still under way. Close physical properties with human bone make sintered hydroxyapatite (HAP) a suitable bioceramic material for hard tissue replacement. Newly developed fully dense nanocrystalline hydroxyapatite (nHAP) bioceramic has better mechanical properties than porous hydroxyapatite and has potential to be used alone, without metallic support in certain applications. When being used as implant devices in the human body, the nHAP bioceramic needs to be machined to the closest possible configuration with minimal surface roughness. This study investigates the machinability of nHAP bioceramic in milling operations. Efforts are focused on the effects of various machining conditions on surface integrity. Surface roughness is measured using a surface profilometer and the machined surface is observed using an optical microscope and a scanning electron microscope (SEM). Chip morphology and tool wear are examined using an optical microscope. Machined surface analysis showed that the surface integrity was good and the required surface roughness value (R[alpha]) of 1 - 1.5 [mu]m was achieved in many experiments. It was found that material removal is caused by brittle fracture without plastic flow. A first order surface roughness model for the end milling of nHAP under dry condition has been described. The mathematical model for surface roughness has been developed based on the cutting parameters: cutting speed, feed and depth of cut. The effects of these parameters on surface roughness have been studied using factorial designs and response surface method. Model analysis showed that all three cutting parameters have significant effect on surface roughness. However the current model has limited statistical power for prediction purposes and it demands a higher order model for accurate prediction of surface roughness value.

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