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Epée fencing involves repeated bouts of high-intensity intermittent exercise with competitions lasting 9-11 hours consisting of Poule (3-minute or first to 5 points) and Direct Elimination (DE; 3x3-minute bouts or first to 15 points) fights. Fencers are required to wear thick protective clothing which could create a hot micro-climate and impede heat loss during exercise. Chapter 4 assessed the physiological demands of epée during simulated competition comprising of Poule and DE fights. Results showed epée is reliant on phosphocreatine and aerobic energy systems shown by decreasing blood lactate concentration from Poule to DE (Poule 1 ~4.5 mmol.L-1; DE 7 ~2.0 mmol.L-1). Maximum heart rate, ratings of perceived exertion, peak speed, training load per minute and percentage of zone 2 accelerations were greater in DE than Poule fights indicating greater physiological strain. There was a considerable energy demand (~13 kcal.min-1) exhibited during the competition. Chapter 5 focussed on the thermoregulatory demands of epée, using the same competition protocol as chapter 4. There was a moderate thermoregulatory demand during Poule fights (gastrointestinal temperature (Tgast) ~38.0°C and mean skin temperature (Tskin) ~34.5°C) and high thermoregulatory demand during DE fights (Tgast >38.0°C pre and >38.5°C post fight and Tskin >35.0°C, thermal sensation ~7.0). Mask temperature was greater than ambient temperature highlighting a hot micro-climate created by protective clothing. Mean skin temperature also increased during recovery between fights for Poule and DE. There was a decrease from DE 1 to DE 7 for distance covered (~900m vs. ~600m) and distance covered per minute (~80.6 m.min-1 vs. ~71.4 m.min-1). Previous research has shown thermoregulatory and performance benefits of cooling on exercise performance. Chapter 5 showed a high thermoregulatory demand of epée especially during DE rounds. Therefore, chapter 7 assessed the effects of external (EXT; evaporative cooling vest (ECV)), and mixed-method (MIX; ECV + cold water ingestion) cooling on physiological, thermoregulatory, perceptual, performance, and cognitive components of epée. Results showed there was a significantly lower Tskin ~0.8-0.9°C and thermal sensation in EXT and MIX cooling interventions than control (CON). There was a limited performance benefit of cooling with greater points difference in MIX compared to CON and EXT. Wheelchair fencing competition structure and protective clothing is similar to able-bodied fencing. Physiological, thermoregulatory, and performance variables were recorded during Poule and DE fights during wheelchair fencing. Results showed a need to ensure training intensity mirrors competition when mixing category A and B fencers through appropriate fight durations and work to rest ratios. Individual thermoregulatory responses existed for each participant for Tgast and Tskin. Mask temperature increased during DE fights (0.34-3.04°C) and Tskin increased during recovery between Poule and DE fights. In conclusion, results of this thesis demonstrate a high physiological and thermoregulatory demand of epée. Furthermore, practical cooling methods between fights lowered Tskin and thermal sensation during DE fights and with a limited performance benefit of MIX for points difference. This thesis provides novel data on thermoregulatory responses of able-bodied and wheelchair epée fencing and movement data of epée using an accelerometer-based athlete tracking system.

Prolonged intermittent exercise or passive rest/daily ambulation in hot environmental conditions have been shown to place the Paralympic athlete under far greater thermal and perceptual strain when compared to the Olympic athlete. Consequently, in wheelchair sports (e.g., wheelchair basketball, rugby and tennis) decrements in performance are evident due to potential dysfunctional thermoregulatory systems because of the impairment type (e.g., spinal cord injury [SCI], amputation etc.). Four main focuses; warm-up, cooling interventions available in SCI, recovery following induced increases in body temperature, and pre-cooling have been investigated in an attempt to provide further insights to the physical preparations of wheelchair rugby players, who have a large proportion of players with an SCI. The current thesis examined the thermoregulatory responses to warming-up and the subsequent effects on simulated performance (chapter 3) in wheelchair rugby players. Those players with an SCI experienced a greater peak core temperature (Tcore) at the end of the simulated game. Notably, a high intensity warm-up improved performance (e.g., increased power output) during the first quarter in some players. In chapter 4, the cooling strategies available to athletes with an SCI were characterised using a meta-analysis. Pre- and per-cooling were found to attenuate the increase in thermal strain in this cohort of athletes. The specific focus on the timing of cooling interventions (pre- and per-cooling), indicated that pre-cooling had a greater effect on Tcore than per-cooling, with the beneficial effects of cooling being greater in athletes with a high SCI lesion level. To further these recommendations, chapter 5 investigated the use of ice slurry ingestion on thermal strain in response to hyperthermia, and as a pre-cooling method in wheelchair rugby players (chapter 6). Reductions in thermal strain (notably heat storage and rectal temperature) from ice slurry ingestion during a 60-minute passive recovery period following hyperthermia were noted. Specifically, when heat loss via evaporation and convection was compromised, a delay in reducing markers of thermal strain was apparent. To investigate the effects of internal cooling on thermal strain in wheelchair rugby players during "real-world" sporting scenarios, the final study employed a passive heating phase replicating typical environmental conditions of the then upcoming Tokyo 2020 Paralympic Games, followed by an intermittent sprint protocol. Prior to the start of the intermittent sprint protocol, ice slurry ingestion reduced thermal strain in the SCI group. No performance benefits were apparent. These novel studies were designed to be used in real-life competitive sporting environments. It may be obvious that wheelchair rugby players with an SCI should consider cooling interventions to offset the rise in thermal strain as a result of daily ambulation in hot/humid environments such as when getting to the sporting venue and/or increased intensity of their preconditioning routines. To date not many coaches have individualised these strategies and this thesis provides practical recommendations and supports the use of 'internal cooling', since ice slurry ingestion does not neglect the rules of game play.

Semiconductor quantum dots (QDs) have inherited the long-standing trope: 'artificial atoms' . On one hand this does great justice to their exquisite light-matter interface, allowing the investigation of fundamental, solid-state quantum optics. On the other hand, it downplays the true complexity of the system, since a single QD electron spin is coupled to approximately 100,000 nuclear spins. Combining these two elements, we have an isolated many-body nuclear ensemble interfaced to a central, proxy qubit, which we can interrogate optically. The system then plays host to a plethora of rich spin physics and complex many-body interactions. This can be exploited in the applied physics of quantum information storage and processing, as well as the fundamental exploration of collective phenomena. This thesis begins with a pedagogical review of QD physics ranging through its bound states; their coupling to light; and the hyperfine and quadrupolar coupling of the nuclei to the electron. The interplay of these couplings becomes a tool for the initialisation, control and readout of the mesoscopic nuclear ensemble, which we use to effect the two main results of this work. The first of these is the realisation of an ultra-precise quantum sensor for the detection of the effective magnetic field of a single nuclear-spin excitation -- a nuclear magnon. In this way we readout magnon population in modes distinguished by polarity and nuclear species. This work constitutes a step towards quantum state tomography of nuclear spin-wave superposition states; a valuable tool in the operation of a magnon-based quantum memory. Moreover the sensing of coherent magnon dynamics offers hints towards emerging quantum correlations in the ensemble. The second result involves the design of a quantum-algorithm for the initialisation of the QD nuclei from infinite temperature to a purified state. This is a key requirement to observe and harness the quantum properties of the system. Importantly, our approach is demonstrably capable of purifying a general spin system down to a single macrostate. Moreover, we argue that our algorithm constitutes the optimum approach in the face of real-world dissipation. Experimentally, we achieve a reduction in the nuclear spin fluctuations of two orders of magnitude and engineer non-trivial, designer nuclear states. We further propose an extension to the algorithm for the preparation of quantum states of nuclei. This work, combined with the recent development of highly coherent QD nuclei, promises a route towards a fully fledged magnon-based quantum register.

This thesis highlights the challenges faced when cooling low dimensional electrons through the progress made towards achieving the coldest possible electron temperature and optimisation of cooling methods. AlGaAs/GaAs heterostructures are two dimensional systems and provide an interesting playground for understanding quantum mechanics. Many fundamental physical phenomena can be explored, including using common effects for thermometry, metrology studies as well as many body effects. At low temperatures, the electrons isolate from the lattice due to phonon freezing and the main source of cooling is through leads. The two–dimensional electron gas is connected to the cryostat by AuGeNi ohmic contacts in order to conduct as well as thermalise through leads to the coldest point of a dilution refrigerator. In order to achieve low electron temperature the contact resistance of the electrical contacts to the sample needs to be minimised. The sample itself must have high enough mobility and sufficient carrier density, while having low resistance to allow thermalisation throughout the system of study. The fabrication, use and characterisation of such devices upon investigating their compatibility with ultra-low-temperature measurements in the micro-Kelvin regime is described. Optimisation of ohmic contacts to these devices was achieved through a systematic study of the contact resistance and investigation of the contacting mechanism. The optimal annealing condition for layered AuGeNi contacts was found to be a rapid thermal anneal at 430?C for 80 seconds, giving a reproducibly low contact resistance of 1 ?mm. Measurement techniques at 4.2 K are compared, with direct electrical measurements made possible by a new test device giving insight into contact resistance. A study of our ohmic contact structure through systematic imaging studies (SEM/EDS) shows they are similar to those in literature. Measurements of standard two-dimensional electron gases showed a superconducting transition below 1 K. This is due to superconductivity in the ohmic contacts to the devices, in series with the measurement, and can be observed. AuGeNi ohmic superconductivity was investigated at lowtemperature on samples of different wafers, annealing conditions and geometries. Through investigation of the contacting mechanism, drawing from literature and the study on our ohmic contacts, this superconductivity is attributed to gold-gallium compounds forming in the contact. The experimental results and their implications are discussed as well as advances to achieving the coldest possible electron temperature. The implications on cooling lowdimensional electrons to less than 1 mK are considered.

The evolution of volcanic sulfur, stratospheric composition and radiative forcing following explosive volcanic eruptions injecting sulfur directly into the stratosphere is well understood. However, how the co-emission of volcanic halogens, climate change, and concurrent sulfate aerosol geo-engineering would alter the atmospheric effects of sulfur-only explosive volcanic eruptions has, previously, been under-researched. In this thesis, aerosol-chemistry-climate model simulations are utilised to show that the co-emission of volcanic halogens alongside sulfur (halogen co-emission) and climate change amplify the volcanic forcing of volcanic eruptions, mainly caused by a reduction in the aerosol lifetime and aerosol size. Stratospheric ozone is shown to be less vulnerable to sulfur-only eruptions, but more sensitive to halogen co-emission eruption scenarios in the future compared to the present-day, due to the projected decline in stratospheric halogen abundance and ozone recovery. An explosive volcanic eruption during stratospheric sulfate aerosol geo-engineering is found to lead to additional negative radiative forcing and total column ozone depletion, but the response is complex and non-additive. This thesis emphasises the need to include volcanic halogen emissions when simulating the climate effects of past or future eruptions as well as the necessity to maintain space-borne observations of stratospheric compounds to better constrain the stratospheric injection estimates of volcanic eruptions. It identifies a novel climate-volcano feedback and highlights the need to re-evaluate the use of constant volcanic forcing typically used in future climate projections. Furthermore, this thesis demonstrates the difficulties associated with maintaining a stable level of radiative forcing in the event of an explosive volcanic eruption during sulfate aerosol geo-engineering.

Solid-state refrigerants that exhibit electrically driven reversible thermal changes, known as electrocaloric (EC) effects, represent a potentially eco-friendly alternative to the greenhouse gases currently used as refrigerants in refrigerators and heat pumps. The phenomenology of EC effects is first briefly discussed, and EC materials and prototypes are then reviewed. Methods for parameterizing EC effects are summarized and critically analyzed with the goal of guiding experimental design and cautioning against potential pitfalls. Multilayer capacitors (MLCs) of PbSc0.5Ta0.5O3 (PST) are demonstrated to be well-suited for cooling applications. The embodiment of highly ordered PST in the MLC geometry yielded a very high breakdown strength in this macroscopic EC working body, allowing the first-order ferroelectric transition to be driven supercritically via fields of up to E = 29.0 V μm ̅1. The resultant EC effects in the large central area of the capacitor were found to peak at 5.5 K near room temperature, and exceed 3 K for starting temperatures that span 176 K. These EC effects compare favourably to magnetocaloric (MC) effects in gadolinium working bodies, suggesting that MC heat-pump design could be repurposed to achieve better performance. Efficiency values for cooling cycles based on MLCs of PST are computed and analyzed by assuming a hypothetical fluid regenerator that is ideal. The refrigerant efficiency γ is defined as the factor by which the coefficient of performance (COP) for any given cycle is reduced due to losses in the working body. For balanced regenerative cycles with large temperature spans near room temperature (e.g. Th − Tc = 50 K), the MLCs of PST are found to attain refrigerant efficiencies of up to γ ~ 97%. MLCs of PST are exploited as the EC working body in a device where Peltier elements that separate it from a load and sink are synchronously driven at constant current and voltage. This protocol is found to increase the efficiency of Peltier cooling, but device optimization is required to evaluate meaningful improvements in efficiency.

Prolonged exercise in hot environmental conditions places the body under far greater physiological and perceptual strain than when exercising at the same intensity in temperate conditions, resulting in an impaired exercise performance or capacity. The exact mechanisms that limit exercise performance are a complex interplay between the physiological and the behavioural systems, likely governed by a rising core temperature (hyperthermia). The three main interventions; hydration, cooling and heat acclimation (HA) have been investigated in an attempt to offset the reduction in exercise performance and capacity observed. The current thesis examined the effect of perceived hydration status (Chapter 3) and pre and per-cooling in isolation or in combination (Chapter 4) on the physiological and perceptual responses during a preload and 15 min timetrial (TT) performance in the heat (35 oC to 40 °C, 50% rh). In Chapter 5, Chapter 6 and Chapter 7 a daily 60 min isothermic HA protocol was investigated on the physiological, perceptual, cognitive function and lipopolysaccharide responses. To further compare whether there was a time course effect over short-term (five days) and medium-term (ten days) upon these responses. Perceived euhydration status when hypohydrated had no effect on 15 min TT performance in moderately trained individuals, when the physiological and perceptual consequences of hypohydration existed. Neither external pre- nor per-cooling in isolation or in combination improved 15 min preloaded TT performance in the heat in highly trained athletes (Chapter 4). Pre-cooling via whole-body cold water immersion (CWI); 22 °C) for 30 min was successful at lowering overall strain for a limited period during the preload; however, by the time participants commenced the TT, the majority of these benefits had worn off, with combined external per-cooling not providing any additional benefit. A short-term (five days) 60 min daily isothermic (target rectal temperature ~38.5 °C) HA protocol provided a sufficient thermal impulse to elicit the necessary thermal adaptations to reduce physiological and perceptual strain when exercising in the heat, without inducing an endotoxin response with medium-term (ten days) offering a more complete adaptation to some systems and offering protection to working memory function.

The Large Hadron Collider is scheduled for upgrade during the middle of this decade, and with it will be upgraded most of the Silicon detectors used in the four experiments of the collider. The upgraded detectors will require a more advanced cooling system that will need to be larger and operate colder than ever before. This thesis describes activities related to the modelling and simulation of the two-phased pumped-loop cooling systems that will cool these Silicon detectors. The development of the tool is described, with details on modelling fluid properties, two-phase flow and some numerical techniques used to facilitate the solver's operation. The experimental setup that was refurbished and upgraded is also described. The setup was used to collect transient data to validate the performance of the tool. The application of the tool is discussed next. The tool was initially validated by simulating a residential heat pump unit. Simulation results were compared against experimental data as well as against another established simulation tool. Residential heat pumps are well-understood two-phase systems which exhibit transients of similar complexity to pumped loop systems. The comparison is, thus, informative. The tool was then used to validate the performance of a laboratory prototype of a pumped loop cooling system representative of the full-scale Silicon detector cooling systems. Startup and step change transients were compared and the tool captured the experimental trends well. The tool is now being used to design a prototype cooling system that will serve as a proof-of-concept for the future detector cooling systems to be deployed on the LHC. The tool is used to study plant behaviour in different dynamic scenarios such as startup, temperature set-point change and detector load change. The full control system to be used for the plant was implemented in the tool and control strategies were iterated. The simulation results are in line with expected behaviour, indicating a readiness of the tool to be used for tasks such as controller parameter tuning, virtual commissioning and operator training.

Underground subway systems provide an efficient high capacity public transportation method for commuters within dense urban areas. Passengers using underground subway systems are subjected to enclosed and crowded environments that must be controlled to maintain tolerable temperatures and ventilation. Modern subway stations and trains are cooled using conventional air conditioning, providing ac- ceptable levels of passenger comfort. However, deep and old subway systems suffer from overheating problems, because they were built before the invention of modern mechanical ventilation and air conditioning, resulting in passenger discomfort and health issues during summer conditions (Gilbey et al., 2011). These systems were not designed to handle the high numbers of passengers and train traffic in current congested cities such as London or New York. The oldest deep subway lines such as the London Underground (1863), Paris (1900), New York (1902), Berlin (1902) , and Moscow Metro (1935), commonly experience overheating problems (Griffiths, 2006). When high ambient temper- atures are combined with heat rejected from train braking and passenger traffic, the temperatures of the tunnels and platforms rise substantially above tolerable levels. The London Underground, particularly the deep sections have become uncomfortable during summer due to congestion and poorly ventilated tunnels, where during the 2006 European heat wave, temperatures as high as 47 ◦C were recorded (Griffiths, 2006). Retrofitting old deep subway systems with air conditioning is often infeasible, because the tunnels only allow enough room for trains. Furthermore, heat rejected from air-conditioning in these narrow tunnel spaces could in fact further exacerbate the overheating problems. As a result, temperatures in old subway tunnels (and surrounding ground) have increased over long term (Botelle et al., 2010). The shallow ground surrounding an old overheated subway system thus has a large potential of low enthalpy energy that can be used for low-grade heating and cooling purposes. Advances in ground source heat pump configurations makes it possible to consider extracting this geothermal energy in an efficient manner (Nicholson et al., 2014). The objective of this thesis is to investigate the use of stand-alone standard closed loop vertical Ground Source Heat Exchangers (GHE) to extract excess heat from old and deep subway tunnels. Because vertical GHEs are physically and structurally independent of the underground subway structure, they can be positioned flexibly around the tunnels. Furthermore, vertical closed loop GSHP systems are standard in urban areas because they can be easily installed, do not require large spaces, and yield good system efficiency (Kavanaugh and Rafferty, 1997). In the UK, they also qualify for subsidies under the UK Government's Renewable Heat Incentive Scheme (DECC, 2014a). To evaluate the potential of vertical GHEs for usefully extracting excess heat from the subway tunnels, one must be able to quantify the net gains: How much useful heat can be feasibly extracted from underground tunnels over a time period ? What is the optimal GHE set-up that could maximize heat extraction ? and what are the resulting temperature drops in the underground tunnels and platforms ? This thesis presents a novel co-simulation framework designed to answer the above questions through simulation modelling. It couples a 1D model of a subway line with a 3D FEM model of vertical ground heat exchangers. The 1D subway model represents spatially averaged transient heat and air flows in the underground, while the FEM model simulates vertical close-loop GHEs next to the subway tunnels. The two models are co-simulated such that information is passed back and forth through a common temperature boundary layer at the outer tunnel walls until both models converge. As a result, the cooling effect of vertical GHEs on the underground climate is examined. In addition, the heat extraction rates of the GHEs placed next to the subway tunnels are compared with standard GHEs. Different arrangements and distances of the GHEs with respect to the tunnels are also examined to achieve the best heat extraction and cooling in the tunnels and stations simultaneously. Finally, partially insulated GHEs are investigated to provide for both heating and cooling demand, because the need to extract heat from the subway is most during the summer months, when demand from building is also for cooling. As an illustrative study, the London Underground's Central line is selected as a representative of an old subway system that suffers from overheating and ventilation problems. The Central Line is one of the busiest line of the London Underground, and suffers from over heating problems particularly during summer conditions, where temperatures above 35 C have been recorded in some areas (Gilbey et al., 2011). Retrofitting the Central Line with vertical closed loop GHEs is investigated to examine its benefits both underground and overground: In addition to the cooling effect in the train tunnels, the heat extracted from the Central Line system is quantified against the heating demand of the surrounding buildings above the tunnels. It is shown that the GHEs enhance the passenger thermal comfort, while providing district heating to the buildings above.

Energy expenditure in humans is partially understood. Sympathetic drive is an important stimulator of brown-adipose tissue-mediated increases in energy expenditure, and it is known that leptin-mediated pathways in part contribute to this. This thesis has sought to understand human energy expenditure further by two different methods. Firstly, we have characterised the first rare human mutations in G protein-coupled receptor 10 (GPR10), a G protein coupled receptor expressed in key brain areas associated with energy homeostasis. GPR10-mediated signalling in the dorsomedial hypothalamus is necessary for the thermogenic effects of leptin. We have undertaken a detailed functional study of the mutations found from the whole exome and targeted resequencing of patients with severe early onset obesity, recruited to the Genetics of Obesity Study (GOOS). We have demonstrated that thirteen of the fifteen mutations found result in a complete or partial loss of function in vitro. We have additionally demonstrated that the mutations resulting in a complete loss of function on wild type receptor. This is important because the human mutations are found in heterozygous form. Secondly, we have conducted a randomised cross-over study of the effects of mild cooling on healthy lean men. We have demonstrated that exposure to temperatures of 16oC for two hours results in an increase in systolic blood pressure and pulse rate, relative to thermoneutral conditions. Cold exposure resulted in a drop in circulating leptin, which in common with previous studies on macronutrient preference in patients with disrupted leptin-melanocortin signalling, is associated with an increase in consumption of high fat food. Cooling is known to be neuroprotective in acute brain injury, and recent published data suggests a protective effect in chronic neurodegenerative conditions by improvements in synaptic plasticity. We have demonstrated an improvement in neurocognition after two hours of mild cooling. We have additionally shown increases in docoshexaenoic acid, a polyunsaturated fatty acid known to play a role in neuroprotection, with a role in maintaining membrane fluidity. These studies broaden our knowledge of human energy homeostasis. They provide evidence for the role of GPR10 in human energy homeostasis, and a rationale for the targeting of GPR10-mediated signalling pharmacologically, and provide some evidence for a role in improved neurocognition in humans.

Neurodegenerative diseases are characterised by the accumulation of misfolded proteins and the progressive loss of synapses, leading eventually to neuronal demise. Synapse loss occurs early in disease and is a reversible process: the pruning and regeneration of synapses, known as structural plasticity, is a continuous process in the brain and represents an important point for therapeutic intervention. Recent evidence has shown that synapse loss in mice models of neurodegeneration is due to a failure of synapse regeneration, driven by failed induction of the cold shock protein, RNA-binding motif protein 3 (RBM3). Overexpression of neuronal RBM3, either by cooling or lentiviral delivery, restores synapse regeneration, preventing subsequent neuronal loss and significantly prolonging survival. How RBM3 regulates structural synaptic plasticity, however, is not well understood. Alongside neuronal pathology, astrocytic activation is a hallmark of many neurodegenerative diseases. Astrocytes play a key role in support of synapses and in regulating structural plasticity. In this thesis, I use in vitro and in vivo approaches to examine the hypothesis that astrocytic RBM3 expression plays a role in synapse formation and structural plasticity, in health and during neurodegeneration. In vitro data indicate that whilst neuronal RBM3 expression is necessary for synapse formation both in development and in cooling-induced structural plasticity, the role of astrocytic RBM3 expression is restricted to non-developmental structural plasticity. Mice with a complete knockout of RBM3 display accelerated disease progression compared to wild type mice with prion disease, supporting a role of both neuronal and astrocytic RBM3 in maintaining structural synaptic plasticity in disease. Finally, expression of RBM3 protein in human blood and brain was quantified. RBM3 was shown to form part of the human cold-shock response in individuals undergoing hypothermia in a number of situations. Given the established link between RBM3 and neuroprotection in mouse models, the data presented support the possibility of therapeutic manipulation of RBM3 for neuroprotection in humans.

Following on from Rio de Janeiro 2016, the Tokyo 2020 Paralympic Games will present a unique challenge for athletes, needing to prepare and adapt to the potential challenging environmental conditions of 20-27°C and ~73% relative humidity. It is well known that during exercise in hot and/or humid climates, able-bodied athletes experience an increase in thermal strain and a reduction in performance compared to cooler/drier conditions. Yet these conditions prove even more problematic for athletes, who as a consequence of their impairment have a dysfunctional thermoregulatory system, such as athletes with a spinal cord injury (SCI). To date, the thermoregulatory responses of athletes with an SCI have been an under-studied area of research. To gain a greater understanding of how heat balance is altered in individuals with an SCI and the thermoregulatory consequences as a result, studies need to first be conducted at rest, removing the additional metabolic heat production from exercise. Although a large majority of athletes with an SCI compete indoors in wheelchair court sports (e.g. wheelchair basketball and rugby), exercising even in these climate-controlled environments has been shown to place these athletes under considerable thermal strain. In light of this, it is remarkable that existing research on the thermoregulatory responses of athletes with an SCI during exercise is scarce, especially studies encompassing real-world sporting environments. Athletes with high level lesions (tetraplegia, TP) are a particularly under-studied population group shown to have a greater thermoregulatory impairment than individuals with low level lesions (paraplegia, PA) during continuous exercise. Thus the aim of this thesis was to investigate the thermoregulatory responses of athletes with an SCI at rest and during real-world sporting scenarios, with specific focus on athletes with TP. Study 1 aimed to determine how evaporative heat loss is altered, as a result of an SCI, compared to the able-bodied (AB), and the effect lesion level has on this response. The results provide evidence that in individuals with TP, even at rest, evaporative heat loss is not large enough to balance the heat load, when evaporation is the primary source of heat dissipation. Even though in individuals with PA Tgi increased by a smaller magnitude and they possessed a greater sweating capacity than individuals with TP, at ambient temperatures above Tsk latent heat loss is insufficient to attain heat balance, compared to the AB. To investigate the thermoregulatory responses of athletes with an SCI during real-world sporting scenarios Study 2 examined athletes with TP compared to athletes with PA during 60 min of intermittent sprint wheelchair exercise on a wheelchair ergometer. The study was conducted in conditions representative of an indoor playing environment for wheelchair rugby and basketball (~21°C, 40% relative humidity). Results demonstrated that, despite similar external work, athletes with TP were under greater thermal strain than athletes with PA. Study 3 s novel approach investigated both physiological responses and activity profiles of wheelchair rugby players during competitive match play. Despite players with TP covering 17% less distance and pushing on average 10% slower, they were under a greater amount of thermal strain than players with non-spinal related physical impairments (NON-SCI). Furthermore, this study demonstrated that players with TP that had a larger body mass, larger lean mass, covered a greater relative distance and/or were a higher point player had a greater end Tgi. These data provide an insight for coaches and support staff regarding which players may need greater attention in regards to cooling strategies or breaks in play. The effectiveness of cooling practices currently employed by athletes with TP has not been previously investigated. Study 4 determined the effectiveness of pre-cooling, using an ice vest alone and in combination with water sprays between quarters, at attenuating thermal strain in athletes with TP. Using the activity profile data from Study 3, an intermittent sprint protocol, conducted on a wheelchair ergometer, was used to represent a wheelchair rugby match. The combination of cooling methods lowered Tgi and Tsk to a greater extent than pre-cooling only, despite neither cooling condition having a positive or negative effect on performance. Unexpectedly, the pre-cooling only condition lowered Tgi, compared to no cooling, throughout the subsequent exercise protocol, even though the reduction in Tsk was not long lasting. This thesis provides comprehensive evidence that athletes with TP experience heightened thermal strain during both rest and real-world sporting scenarios compared to the AB, athletes with PA, and within the sport of wheelchair rugby. Athletes with TP should employ practices, such as appropriate cooling methods or alter playing tactics to reduce thermal strain and the likelihood of attaining a heat related injury.

Exhausting the thermal power from a fusion tokamak is a critical engineering challenge. The life of components designed for these conditions has a strong influence on the availability of the machine. For a fusion power plant this dependence becomes increasingly important, as it will influence the cost of electricity. The most extreme thermal loading for a fusion power plant will occur in the divertor region, where components will be expected to survive heat fluxes in excess of 10 MW/m2 over a number of years. This research focussed on the development of a heat sink module for operation under such conditions, drawing on advanced cooling strategies from the aerospace industry. A reference concept was developed using conjugate Computational Fluid Dynamics. The results were experimentally validated by matching Reynolds numbers on a scaled model. Heat transfer data was captured using a transient thermochromic liquid crystal technique. The results showed excellent agreement with the corresponding numerical simulations. To facilitate comparison against other divertor heat sink proposals, a nondimensional figure of merit for cooling performance was developed. When plotted against a non-dimensional mass flow rate, the reference heat sink was shown to have superior cooling performance to all other divertor proposals to date. Results from Finite Element Analysis were used in conjunction with the ITER structural design criteria to life the heat sink. The sensitivity of life to both boundary conditions, and local geometric features, were explored. The reference design was shown to be capable of exceeding the life requirements for heat fluxes in excess of 15 MW/m2. A number of heat sinks, based on the reference design, were fabricated. These underwent non-destructive testing, before experimentation in a high-heat flux facility developed by the author. The heat transfer performance of the tested modules was found to exceed that predicted by numerical modelling, which was concluded to be caused by the fabrication processes used.

Cooling of burns is key to acute burn management, and is a widely accepted practice in modern medicine. Cooled burns are less painful, heal more quickly, require fewer skin grafts, and leave less scarring. The vast majority of research in this area has used animal models, and focussed on optimising cooling, rather than investigating its mechanism. Cooling is not without risks and limitations, and understanding the mechanism might lead to pharmacological alternatives. We aimed to develop a standardised human model for burning and cooling, and used this to investigate the transcriptional and proteomic effects of burning and cooling. This model used redundant skin discarded during surgery, and purpose-built apparatus for burn creation and cooling. Microvascular and other histological changes were demonstrated in response to burning, and modified by cooling. RNA and protein extracts from cooled and uncooled samples of burned and unburned skin were analysed with RNAseq and LC/MS3 techniques, respectively. Findings were validated with immunohistochemistry and qPCR. We demonstrated that there was a significant change in 22% of the transcriptome of the skin, with gene ontologies related to wounding, angiogenesis, inflammation, haemostasis, innate immune response, degranulation and chemotaxis among those significantly upregulated. Downregulated ontologies included keratinisation, epidermal differentiation, hair follicle development and cornified envelope. Cooling of burns significantly increased the transcription of genes related to hair follicle differentiation while reducing the transcription of heat-shock proteins. Burning caused significant activation of the complement and coagulation cascades, while cooling reduced the scale of these changes. Immunohistochemistry confirmed complement proteins, including the membrane-attack complex (MAC) localised to the immediate area of the blistered epidermis, as were fibrinogen and platelets, with evidence of early neutrophil migration. We have demonstrated the role of complement and coagulation activation as a damage-amplifying agent following thermal injury, and the role of cooling in attenuating this effect. The preservation of transcription of follicle-related genes indicates preservation of epidermal appendages as sites of re-epithelialisation. Complement blockade is already utilised in the management of autoimmune conditions, and transplant rejection, and could modify the complement activation in burns, reducing injury-progression, and the associated systemic effects, and improving patient outcomes.

The increasing globalization of elite soccer match-play means that soccer players are likely to compete in hot, hypoxic and hot-hypoxic environments over a season. Soccer match-play studies have identified a marked decline in soccer-specific physical performance in the heat and hypoxia due to increasing body temperatures and a reduction in partial pressure of oxygen (PO2), respectively. As hot environments are more prevalent in elite soccer match-play, cooling strategies have been assessed within the literature in an attempt to alleviate these heat-induced- decrements. However, utilising a soccer match-play design makes environmental and interventional inferences difficult to ascertain, as a plethora of match factors and adaptive pacing strategies cause high variability in key physical performance measures within soccer match-play. Therefore, the three experiments within thesis aimed to assess the reliability and validity of a non-motorised treadmill (NMT) based soccer-specific simulation [intermittent Soccer Performance Test - (iSPT)], to enable the reliable investigation of environmental stress on soccer performance and the efficacy of pre- and half-time-cooling to attenuate any heat- induced-decrements. The purpose of experiment 1 was to investigate the reliability and validity of iSPT which utilised a novel speed component called a ‘variable run’. This speed component quantified the distance covered at a self-selected speed above the second ventilatory threshold (VT2speed), which attempted to delimit a ‘high-intensity’ threshold. Twenty male University soccer players completed one maximal oxygen (O2) uptake (V̇ O2max ) test, three familiarisation (FAM) sessions and one peak speed assessment (PSA) on the NMT, before completing the iSPT twice (iSPT1 and iSPT2). The total distance, sprint distance and high-speed distance covered were 8,952 ± 476 m, 1,000 ± 74 m and 2156 ± 140 m, respectively. No significant difference (p>0.05) was found between repeated trials of the iSPT for all physical performance measures and physiological responses. Reliability measures between iSPT1 and iSPT2 showed good agreement [Coefficient of variation: <4.6%; Intraclass correlation: >0.80] compared with statistical guidelines. Furthermore, the variable run phase showed high speed running capacity was significantly decreased (p<0.05) in the last 15 min compared to the first 15 min, showing parity with previous match-play data. Experiment 1 validated the iSPT as a NMT based soccer- specific simulation compared to previous match-play data, and is a reliable tool for assessing and monitoring the physical performance and physiological responses in soccer players. Successfully completing the aim of experiment 1 facilitated the quantification of hot (HOT), hypoxia (HYP) and hot-hypoxia (HH) mediated decrements on maximal soccer-specific performance in experiment 2. Twelve male University soccer players completed three FAM sessions, one PSA and four randomised crossover experimental trials of the intermittent Soccer Performance Test (iSPT) in normoxic-temperate (CON: 18oC 50% rH), HOT (30oC; 50% rH), HYP (1,000m; 18oC 50% rH) and HH (1,000m; 30oC; 50% rH). Physical performance and its performance decrements, body temperatures [rectal (Tre), skin (Tsk) and estimated muscle temperature (Tmu)], heart rate (HR), arterial blood oxygen saturation (SaO2), perceived exertion, thermal sensation (TS), body mass changes, blood lactate (Bla) and plasma volume were all measured. Performance decrements were similar in HOT and HYP [total distance (-4%), high- speed distance (~-8%) and variable run distance (~-12%) covered] and exacerbated in HH [total distance (-9%), high-speed distance (-15%) and variable run distance (-15%)] compared to CON. A 4% increase in peak sprint speed was present in HOT compared with CON and HYP and 7% greater in HH. The sprint distance covered was unchanged (p > 0.05) in HOT and HYP and only decreased in HH (-8%) compared with CON. Body mass (-2%), temperatures (+2- 5%) and TS (+18%) were altered in HOT. Furthermore, SaO2 (-8%) and HR (+3%) were changed in HYP. Similar changes in body mass and temperatures, HR, TS and SaO2 were evident in HH compared to HOT and HYP, however, Bla (p < 0.001) and plasma volume (p <0.001) were only significantly altered in HH. Perceived exertion was elevated (p < 0.05) by 7% in all conditions compared with CON. Regression analysis identified that absolute TS and absolute rise in Tsk and estimated Tmu (r = 0.82, r = 0.84 r = 0.82, respectively; p <0.05) predicted the hot-mediated-decrements in HOT. The hot, hypoxic and hot-hypoxic environments impaired physical performance during iSPT. Future interventions should address the increases in TS and body temperatures, to attenuate these decrements in physical performance. Experiment 3 of this thesis aimed to identify three pre- and half-time-cooling strategies to attenuate the heat-induced-decrements previously seen in experiment 2. Eight male University soccer players completed four randomised experimental trials of iSPT, three with cooling and one control (i.e. No pre- or half-time cooling: CON). The pre- and half-time-cooling interventions involved were 30-min or 15 min in duration, respectively. Ice slurry ingestion (SLURRY), ice packs (PACKS) covering the upper legs and mixed-methods (MM: PACKS and SLURRY) were utilised as the three cooling interventions. Physical performance and its performance decrements, body temperatures (Tre, Tsk and estimated Tmu), HR, perceived exertion, TS, body mass changes and Bla were all measured. Compared with CON, both PACKS and SLURRY pre-cooling significantly reduced (p > 0.05) central (Tre) and peripheral (Tsk and estimated Tmu) body temperatures prior to iSPT, respectively. However, body temperature and physical performance were unchanged during the first half of PACKS and SLURRY compared with CON. The MM pre-cooling significantly reduced all body temperatures and TS both prior to and during the first half which coincided with an improvement in total distance (+3%), high-speed distance (+4%) and variable run distance (+5%) covered. Half-time-cooling via PACKS, SLURRY and MM had no ergogenic effect (p> 0.05) upon physical performance in the second half, compared with CON. The 30 min of mixed-method pre-cooling, via ice packs placed upon the upper legs and ice slurry ingestion, significantly improved simulated soccer performance during the first half, however, future research should identify a valid half-time-cooling strategy to offer further improvements to physical performance in the second half. The main findings within this thesis revealed that the iSPT showed validity with previous soccer match-play data and strong reproducibility between two tests (iSPT1 and iSPT2). Furthermore, the variable run component showed efficacy as sensitive measure of the decrements in high-speed running capability. As the iSPT demonstrated low test-retest error compared with the statistical guidelines and previous NMT based soccer-specific simulations, any changes to physical performance can be attributed to an intervention and not the variability of the measure, unlike in soccer match-play situations. No difference was seen for all physical performance measures in both HOT and HYP, however, the heat and hypoxic-induced- decrements stem from increasing body temperatures and changes to both SaO2 and HR, respectively. Such decrements may have a detrimental effect upon the match outcome. These heat-induced-decrements were attenuated in the first half after 30 min of mixed-methods pre- cooling, however, the 15 min of mixed-methods half-time-cooling did not significantly improve any physical performance measure in the second half. The mixed-method pre-cooling strategy tested within this thesis could go some way in maintaining physical performance during the first half of soccer match-play in hot environments (~30oC). However, future laboratory based research within a controlled environment should look to assess different combinations, times and strategies of cooling which may be applicable to the time constraints associated with elite soccer.

Modern gas turbine engines run at extremely high temperatures which require the high pressure turbine blades to be extensively cooled in order to reach life requirements. This must be done using the minimum amount of coolant in order to reduce the negative impacts on the cycle efficiency. In the design process the cooling configuration and stress distribution must be carefully considered before verification of the design is conducted. Improvements to all three of these blade design areas are presented in this thesis which investigates internal cooling systems in the form of ribbed, radial passages and leading edge impingement systems. The effect of rotation on the heat transfer distribution in ribbed radial passages is investigated. An engine representative triple-pass serpentine passage, typical of a gas turbine mid-chord HP blade passage, is simulated using common industrial RANS CFD methodology with the results compared to those from the RHTR, a rotating experimental facility. The simulations are found to perform well under stationary conditions with the rotational cases proving more challenging. Further study and simulations of radial passages are undertaken in order to understand the salient flow and heat transfer features found, namely the inlet velocity profile and rib orientation relative to the mainstream flow. A consistent rib direction gives improved heat transfer characteristics whilst careful design of inlet conditions could give an optimised heat transfer distribution. The effect of rotation on the heat transfer distribution in leading edge impingement systems is investigated. As for the radial passages, RANS CFD simulations are compared and validated against experimental data from a rotating heat transfer rig. The simulations provide accurate average heat transfer levels under stationary and rotating conditions. The full target surface heat transfer in an engine realistic leading edge impingement system is investigated. Experimental data is compared to RANS CFD simulations. Experimental results are in line with previous studies and the simulations provide reasonable heat transfer predictions. A new method of combined thermal and mechanical analysis is presented and validated for a leading edge impingement system. Conjugate CFD simulations are used to provide a metal temperature distribution for a mechanical analysis. The effect of changes to the geometry and temperature profile on stress levels are studied and methods to improve blade stress levels are presented. The thermal FEA model is used to quantify the effect of HTC alterations on different surfaces within a leading edge impingement system, in terms of both temperature and stress distributions. These are then used to provide improved target HTC distributions in order to increase blade life. A new method using Gaussian process regression for thermal matching is presented and validated for a leading edge impingement case. A simplified model is matched to a full conjugate CFD solution to test the method's quality and reliability. It is then applied to two real engine blades and matched to data from thermal paint tests. The matches obtained are very close, well within experimental accuracy levels, and offer consistency and speed improvements over current methodologies.

The commercial polycrystalline superalloy RR1000 developed for turbine disc applications contains a large number of alloying elements. This complex alloy chemistry is required in order to produce appropriate microstructures and the required mechanical properties, such that the most important strengthener γʹ displays complex alloy chemistry. The broad aim of this project is to develop an approach to measuring the composition of γʹ precipitates at a broad range of length scales from nanometres to hundreds of nanometres, and subsequently develop a better understanding of the role of thermodynamics and diffusion kinetics on γʹ phase separation and precipitate growth. A solution of the absorption-corrected EDX spectroscopy to spherical particles was developed in our work, therefore enabling the quantitative analysis of precipitates' composition using an absorption-corrected Cliff-Lorimer approach. By performing this quantification, size-dependent precipitate compositional variations were obtained. Examination of this quantitative approach was compared to thermodynamic calculations of primary γ' precipitates possessing equilibrium compositions. Given the development of semi-quantitative compositional measurements for spherical γʹ precipitates and that cooling is one of the most common and critical regimes in physical metallurgy of Ni-based superalloys, this approach was then applied to study the local compositional variations that are induced in γ' precipitates when the alloy RR1000 undergoes different cooling rates. These measured compositions have been compared to detailed thermodynamic calculations and provide new experimental evidence of the importance of the dominant role of aluminium antisite diffusion in determining the low-temperature growth kinetics of fine-scale γ' precipitates. We have applied a similar analysis approach to study the compositional variations of γʹ cores within the class of secondary precipitates upon cyclic coarsening and reversal coarsening. It was shown that supersaturated Co in secondary γʹ exhibits an overall trend towards the equilibrium but Co content can significantly increase as γʹ coarsens. It was demonstrated that the limited elemental diffusivity in γ and γʹ compared to the observed coarsening rate in the coarsening regime results in the long-lasting Co supersaturation in γʹ and builds up elemental enhancements or depletions. These inhomogeneous elemental distributions produce compressive elastic constraints on large-scale secondary γʹ, therefore inducing morphological instability of these γʹ and causing the reversal coarsening. These results enable us to better understand the role that both thermodynamics and limited diffusion kinetics plays in controlling the complex microstructures of γ' precipitates.

The tips of unshrouded, high-pressure turbine blades are prone to significantly high heat loads. The gap between the tip and over-tip casing is the root cause of undesirable over-tip leakage flow that is directly responsible for high thermal material degradation and is a major source of aerodynamic loss within a turbine. Both must be minimised for the safe working and improved performance of future gas-turbines. A joint experimental and numerical study is presented to understand and characterise the heat transfer and aerodynamics of unshrouded blade tips. The investigation is undertaken with the use of a squealer or cavity tip design, known for offering the best overall compromise between the tip aerodynamics, heat transfer and mechanical stress. Since there is a lack of understanding of these tips at engine-realistic conditions, the present study comprises of a detailed analysis using a high-speed linear cascade and computational simulations. The aero-thermal performance is studied to provide a better insight into the behaviour of squealer tips, the effects of casing movement and tip cooling. The linear cascade environment has proved beneficial for its offering of spatially-resolved data maps and its ability to validate computational results. Due to the unknown tip gap height within an entire engine cycle, the effects of gap height are assessed. The squealer's aero-thermal performance has been shown to be linked with the gap height, and qualitative different trends in heat transfer are established between low-speed and high-speed tip flow regimes. To the author's knowledge, the present work is the first of its kind, providing comprehensive aero-thermal experimental research and a dataset for a squealer tip at engine-representative transonic conditions. It is also unique in terms of conducting direct and systematic validations of a major industrial computational fluid dynamics method for aero-thermal performance prediction of squealer tips at enginerepresentative transonic conditions. Finally, after recognising the highest heat loads are found on the squealer rims, a novel shaped squealer tip has been investigated to help improve the thermal performance of the squealer with a goal to improve its durability. It has been discovered that a seven percent reduction in tip temperature can be achieved through incorporating a shaped squealer and maximising the internal cooling performance.

In order to meet the increasingly strict emissions targets required in modern civil aviation, lean burn combustors are being pursued as a means to reduce the environmental impact of gas-turbine engines. By adopting a lean air/fuel mixture NOx production may be reduced. The increase in proportional amount of high pressure air entering directly into the combustor reduces the amount available for cooling of the combustor liner tiles. A reduced mass of air places restrictions on the porosity of cooling arrays, requiring a departure from applications of pedestal and slotted film cooling typically used to cool double skin combustor liners. An alternative approach applied to lean burn combustors places impingement and effusion arrays on the cold and hot skins respectively for cooling of both sides of the hot liner skin. Although impingement cooling is well established as a means of promoting forced convection cooling, there are many areas on a liner tile where cooling behaviour is not well characterised. Additionally, film cooling reduces combustive efficiency and increases the production of NOx and CO, prompting interest in reducing its use in combustor cooling. The research for this thesis has focussed on investigations into current and proposed geometries to identify methods to enhance cold side cooling in lean burn applications. A fully modelled combustor liner tile has been used for investigation into the impact of structural and pressure blockages on cold side cooling performance of an impingementeffusion array using a transient liquid crystal technique to measure heat transfer performance. Research has found structural blockages can reduce heat transfer performance to ~60% of typical values, with crossflow development due to pressure blockage producing similar reductions in Nusselt values to ~70% of typical. A second investigation explored enhanced cooling geometries combining a distributed impingement feed over roughened channels of pedestals at variable height (H/D) and pitch (P/D). A newly proposed 'Shielded Impingement' concept combines full height pedestals, to protect impingement jets from developing crossflow, with quarter height pedestals for turbulence enhancement of crossflow cooling. The research has found that Shielded Impingement geometries displayed the strongest cooling performance of all tested designs due primarily to increased downstream Nusselt numbers. Pressure losses were comparable to short pedestal geometries, with little apparent effect of full height pedestals. Low pressure losses mean that application to extended channels in line with the full tile geometry is possible.

This thesis presents work on a holistic approach for improving the overall design of solar cooling systems driven by solar thermal collectors. Newly developed methods for thermodynamic optimization of hydraulics and control were used to redesign an existing pilot plant. Measurements taken from the newly developed system show an 81% increase of the Solar Cooling Efficiency (SCEth) factor compared to the original pilot system. In addition to the improvements in system design, new efficiency factors for benchmarking solar cooling systems are presented. The Solar Supply Efficiency (SSEth) factor provides a means of quantifying the quality of solar thermal charging systems relative to the usable heat to drive the sorption process. The product of the SSEth with the already established COPth of the chiller, leads to the SCEth factor which, for the first time, provides a clear and concise benchmarking method for the overall design of solar cooling systems. Furthermore, the definition of a coefficient of performance, including irreversibilities from energy conversion (COPcon), enables a direct comparison of compression and sorption chiller technology. This new performance metric is applicable to all low-temperature heat-supply machines for direct comparison of different types or technologies. The achieved findings of this work led to an optimized generic design for solar cooling systems, which was successfully transferred to the market.

Thermal sensitivity has been of scientific interest for almost a century. Despite this, several research questions within this field remain unanswered, particularly regarding the specific distribution of thermal sensitivity to cold across the human body. Additionally, while exercise is known to cause a cold stimulus to be perceived as less unpleasant according to the principle of thermal alliesthesia, less has been reported on the effects of exercise on thermal sensitivity to cold. With applications mainly related to clothing insulation and design in mind, the present research project aimed to investigate thermal sensitivity to cold at whole body segments, as well as within body segments, at rest and during exercise. Additionally, a comparison of thermal sensitivity to cold between genders and between ethnic groups was also performed.

Joint behaviour in fire is currently one of the most important topics of research in structural fire resistance. The collapse of World Trade Center buildings and the results of the Cardington full-scale eight storey steel framed building fire tests in the UK have demonstrated that steel joints are particularly vulnerable during the heating and cooling phases of fire. The main purpose of this research is to develop robust joints to CFT columns that are capable of providing very high rotational and tying resistances to make it possible for the connected beam to fully develop catenary action during the heating phase of fire attack and to retain integrity during the cooling phase of fire attack. This research employed the general finite element software ABAQUS to numerically model the behaviour of restrained structural subassemblies of steel beam to concrete filled tubular (CFT) columns and their joints in fire. For validation, this research compared the simulation and test results for 10 fire tests previously conducted at the University of Manchester. It was envisaged that catenary action in the connected beams at very large deflections would play an important role in ensuring robustness of steel framed structures in fire. Therefore, it was vital that the numerical simulations could accurately predict the structural behaviour at very large deflections. In particular, the transitional behaviour of the beam from compression to catenary action presented tremendous difficulties in numerical simulations due to the extremely high rate of deflection increase. This thesis will explain the methodology of a suitable simulation method, by introducing a pseudo damping factor. The comparison between the FE and the experimental results demonstrates that the 3-D finite element model is able to successfully simulate the fire tests. The validated ABAQUS model was then applied to conduct a thorough set of numerical studies to investigate methods of improving the survival temperatures under heating in fire of steel beams to concrete filled tubular (CFT) columns using reverse channel connection. This study investigated five different joint types of reverse channel connection: extended endplate, flush endplate, flexible endplate, hybrid flush/flexible endplate and hybrid extended/flexible endplate. The connection details investigated include reverse channel web thickness, bolt diameter and grade, using fire-resistant (FR) steel for different joint components (reverse channel, end plate and bolts) and joint temperature control. The effects of changing the applied beam and column loads were also considered. It is concluded that by adopting some of the joint details to improve the joint tensile strength and deformation capacity, it is possible for the beams to develop substantial catenary action to survive very high temperatures. This thesis also explains the implications on fire resistant design of the connected columns in order to resist the additional catenary force in the beam. The validated numerical model was also used to perform extensive parametric studies on steel framed structures using concrete filled tubular (CFT) columns with flexible reverse channel connection and fin plate connection to find means of reducing the risk of structural failure during cooling. The results lead to the suggestion that in order to avoid connection fracture during cooling, the most effective and simplest method would be to reduce the limiting temperature of the connected beam by less than 50°C from the limiting temperature calculated without considering any axial force in the beam.