Transient ischaemic attack (TIA) and minor stroke are associated with a high risk of recurrent stroke which can be predicted with a clinical rule and reduced with urgent treatment. Delay in accessing assessment and vascular risk factor modification should therefore be as short as possible, yet little is known in the UK about where patients seek care and the key influences of the time to contact healthcare services. However, using cohort studies to answer questions on healthcare access requires an assessment of how well such cohorts represent the wider population. Within the primary care consultation, the recognition of TIA is an important step in the care pathway as definitive treatment is initiated by specialists, yet TIA presentations are not common for individual GPs and difficulties in diagnosis may be due to low clinical exposure in routine practice or inadequacies in training. For patients where GPs suspect that TIA may be the cause of symptoms, inaccurate risk prediction and diagnosis of TIA can result in delay to definitive care and the existing tools for prognosis and diagnosis have been exclusively derived from clinical assessments in secondary care rather than primary care.

Critical components in coal-fired power plants such as final superheater heat exchangers experience severe conditions associated with high metal temperatures and high temperature gradients during base load and transient operations. Such adverse conditions could significantly reduce the life span of the components, especially due to the requirement of greater plant flexibility that is an essential part of the global power system transformation. Integrated thermofluid process models can be employed to obtain a better understanding of the relationship between the operational conditions and the metal temperatures. Thus, a methodology was developed to model radiant superheater heat exchangers in steady state and transient operations. The methodology is based on a network approach which entails solving the transient one-dimensional forms of the conservation equations for mass, energy and momentum. The model building blocks account for the convective thermal resistance on the steam side, the conductive thermal resistances of the tube wall and scaling or fouling on the tube walls, as well as the convective and radiative thermal resistances and direct radiation on the flue gas side. The model captures the physical layout of the tube passes in a tubesheet via the arrangement of the network building blocks. It is also possible to connect tubesheets together across the width of the boiler as per the arrangement in a real plant. The modelling methodology was first used to develop a process model of a convective cross-flow primary superheater heat exchanger with complex flow arrangement. The dual-tube 12-pass superheater was discretized along the flue gas flow path as well as along the steam flow path. The model was qualitatively validated using real plant data from literature and for reference purposes also systematically compared to conventional lumped parameter models. The ability of the model to analyse the effect of ramp rate during load changes on the tube metal temperature was demonstrated, as well as the ability to determine the maldistribution of flow and temperature on the steam and flue gas sides. The methodology was also applied to model a U-shaped radiant superheater heat exchanger. Due to the challenges associated with obtaining comprehensive real plant data in an industrial setting, a validation methodology was proposed that is based on a combination of plant design C-schedules and a boiler mass and energy balance, as well as limited plant measurements. The consistent comparisons with C-schedule data provide evidence of the validity of the model, which was further demonstrated via the comparisons with real plant data. The model allows prediction of the steam mass flow and temperature distribution going into the outlet stub headers as well as the main outlet headers for different inlet flow and temperature distributions on the steam and flue gas sides. These results were compared to detail real-plant measurements of the outlet header temperatures. The model also allows prediction of the metal temperatures along the length of the tubes which cannot readily be measured in the plant. The model was applied to demonstrate the impact of different operational conditions on the tube metal temperatures. Such integrated process models can be employed to study complex thermofluid process phenomena that may occur during intermittent, transient and low load operation of power plants. In addition, such models could be useful for predictive and preventative maintenance as well as online condition monitoring.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第21595号 / 理博第4502号 / 新制||理||1646(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)教授 寺嶋 正秀, 教授 林 重彦, 教授 竹腰 清乃理 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

京都大学 / 新制・課程博士 / 博士(理学) / 甲第23033号 / 理博第4710号 / 新制||理||1675(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)教授 寺嶋 正秀, 教授 林 重彦, 教授 渡邊 一也 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

京都大学 / 新制・課程博士 / 博士(医科学) / 甲第23472号 / 医科博第131号 / 新制||医科||9(附属図書館) / 京都大学大学院医学研究科医科学専攻 / (主査)教授 滝田 順子, 教授 髙折 晃史, 教授 江藤 浩之 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Diploma thesis deals with ferroresonance phenomena which is present in power networks with saturable inductances and capacitors. A distinction drawn between resonance and ferroresonance will highlight the specific. Lack of knowledge means that it is readily considered responsible for a number of unexplained destructions or malfunctionings of equipment. In the work is a description of such behaviours means risk for electrical power systems. Finally, last part presentat produkt by ABB company intend for damping oscillations and summaries measures on it.

The exponential advancements in the field of electronics and power generation have resulted in increased pressure on the thermal management of these systems where the desire for enhanced heat transfer is prevalent. A technique for enhancing heat transfer that has gained sufficient attention over the past two decades is to suspend nano-sized metallic particles in a base fluid in order to enhance its thermophysical properties. Fluids produced in such a manner are commonly termed nanofluids. Due to the promising heat transfer capabilities of nanofluids, many industrial applications are beginning to implement these fluids in their thermal practices. One of the potential applications where nanofluids may be used which has received a great deal of research attention is jet-impingement heat transfer. Concerning the existing publications on nanofluid jet impingement, most works within the steady state regime are limited to the cooling of Al2O3-water nanofluids, while transient studies do not account for cooling without the effects of boiling phenomena and for surfaces other than steel. In this study, six particle volume fractions of TiO2-water ranging between 0.025 and 1% were prepared and characterised for appropriate cooling tests. The study was conducted within both the steady and transient state with the main objective of evaluating the thermal performance of the selected nanofluid and to determine the optimum particle concentration for jet-impingement cooling applications. Therefore, an experimental rig was designed and manufactured where a copper target surface of 42 mm was impinged upon by a 1.65 mm orifice nozzle at a non-dimensional nozzle-to-target height of 4. The results indicated that the use of nanofluids in impingement applications produced adverse effects, depending on the particle fraction considered. With respect to the steady-state cooling tests, the copper surface was subjected to a constant heat flux of 145 watt and cooled by the different fluids at Reynolds numbers ranging between approximately 10 000 and 30 000. A maximum enhancement of 14.75% was observed in the measured Nusselt numbers, which occurred at a particle volume concentration of 0.05%. When increasing the volume fraction above 0.1%, unfavourable effects were observed for the heat transfer of the system in comparison with the base case tests of DI-water. Such trends were characterised by the trade-off between the enhancement in thermal conductivity and viscosity, both of which were increased with an increase in particle concentration. As for the effect of Reynolds number on the resulting thermal performance, a directly proportional relation was shown and could be described by the forced convection effect. The transient impingement tests showed that particle concentrations less than 0.1% produced an enhancement in cooling efficiency, while those of higher volume fractions showed negative effects. According to these tests the maximum enhancement was also obtained at a volume fraction of 0.05% and produced an average cooling efficiency enhancement of 16%. The results of the investigation clearly showed that the use of TiO2-water nanofluids in jet-impingement cooling applications produced thermal enhancement depending on the selected particle concentration. / Dissertation (MEng)--University of Pretoria, 2019. / NRF / Mechanical and Aeronautical Engineering / MEng / Unrestricted

The transient receptor potential (TRP) are cation channels mostly permeable to both monovalent and divalent cations. ThermoTRP is a specific group of directly thermally activated TRP channels. The vanilloid transient receptor potential 3 (TRPV3) is an ion channel widely expressed in keratinocytes, that is implicated in the regulation of skin homeostasis, thermo- sensing, nociception and development of itch sensation. Our results show the importance of the cytoplasmic inter-subunit interface in the heat sensitivity of TRPV3. As there is a structural analogy within the vanilloid receptors, our hypothesis of the identified important region is supposed to be valid also for other thermally activated TRPV receptors (TRPV1, TRPV2 and TRPV4). We have proved that TRPV3 is a substrate for ERK1/2 protein kinase (kinase regulated by extracellular signal 1 and 2) and we have identified TRPV3 phosphorylation sites that may be direct targets for ERK1/2. Of these residues, threonine 264 has been shown to be the main phosphorylation site responsible for TRPV3 sensitization mediated by ERK kinase. In human keratinocytes, the phosphorylation might be physiologically and pathophysiologically important in processes of TRPV3 sensitization mediated by MAPK signaling pathway. The transient receptor potential ankyrin 1...

Sprites, halos, and elves are members of a family of short-lived, luminous phenomena known as Transient Luminous Events (TLEs), which occur in the middle atmosphere. Sprites are vertical glows occurring at altitudes typically ranging from ~40 to 90 km. In video imagery they exhibit a red color at their top, with blue tendril-like structure at low altitudes. Elves are disk-like glows that occur at the base of the ionosphere, with diameters of ~100-300 km, and have very short lifetimes (~2-3 ms). Halos are diffuse glows that occur at low altitudes, have diameters <100 >km, and have a duration that may last up to 10s of ms. A majority of the studies of TLEs have taken place over the Midwestern U.S. where they were first discovered. This area produces large thunderstorms, which in turn generate large lightning discharges that have been associated with the formation of TLEs. Studies have used the low frequency radiation that initiates with these strokes to study characteristics of these events. This low frequency radiation has been used to determine where large numbers of TLEs may occur. Extreme southern Brazil is a region of the globe believed to have many TLEs, but few studies on these phenomena. Two collaborative campaigns involving Utah State University proceeded in 2002- 2003, and in 2006. Multiple TLE images were made, proving this is, indeed, a region of the globe where these types of events are prominent. In particular, one storm in February 2003 produced over 440 TLEs imaged by USU video cameras. Of these events, over 100 of them had associated halos. Statistical studies for halos previously had been performed in the U.S., but never abroad. Also, several events from the February storm have been associated with negative cloud to ground lightning, a surprising occurrence, as to date, less than a handful of such events have ever been witnessed or published. In analyzing the TLEs from this campaign, we have shown the halos are similar to those seen in the U.S., even though the storms may be somewhat different. Also, detailed analyses of the negative events show both temporal and spatial morphology heretofore never reported on.

No description available.