No description available.

This thesis presents a search for the supersymmetric partner of the top quark in the final state with one lepton. The search focuses especially in the region of the parameter space where the 2-body decay dominates. The analysis is performed using LHC full Run 2 data at √s = 13 TeV as recorded by the ATLAS detector. No significant excess above the backgrounds is observed, and 95% confidence level exclusion limits are calculated in the stop-neutralino mass plane. Stops are excluded up to 1200 GeV in the low neutralino mass scenario of below 400 GeV. The Tile Calorimeter is part of the ATLAS calorimeter system whose main task is to measure the energy of hadrons. A performance study is conducted on the Tile Calorimeter using muons from W boson decay originating from proton-proton collisions. Each calorimeter cell response is measure in data and compared with detector simulation.  The azimuthal cell response uniformity is also investigated using a likelihood method. Overall, a good data to detector simulation agreement and azimuthal uniformity is observed which shows well-calibrated cells and uniform responses among the calorimeter modules.

Adiabatic calorimetry provides accurate and precise specific heat (Cp) data. From this data, thermodynamic functions may be calculated. Cu2OCl2, melanothallite, became of interest as part of a study of a particular thermochemical cycle. The experimental specific heat data and the calculated thermodynamic functions are reported here. Free energies of formation, calculated from the thermodynamic functions, suggest the particular cycle of interest with this compound as an intermediate is not feasible; uncertainty as to the accuracy of CuO and CuCl2 data used in the calculations indicate further study may be necessary. Upon collection of the specific heat data, an antiferromagnetic transition was observed at 70 K; this led to examination of the magnetic heat capacity and entropy of the transition in melanothallite. The entropy of the transition was estimated to be 18.1 % and 7.5 % of 2Rln2 by two methods. A theoretical calculation using an Ising model produced a result of 39 %. This is consistently low when compared to the entropies of the antiferromagnetic transitions of CuO and CuCl2. This suggests geometric frustration. This thesis reports the thermodynamic functions calculated from the specific heat; the examination of the magnetic entropy; and repairs to an adiabatic apparatus involved in the collection of this data.

3D-printing is a new and upcoming manufacturing technique that can significantly reduce time and material losses in production. Fused deposition modeling (FDM) is one of the most commonly used 3D-printing methods for processing conventional thermoplastic polymers. To reduce the printing time and usage of material via FDM technology, a user typically specifies infill density. Therefore, it is important to understand how this printing parameter affects the fire and mechanical properties of the 3D-printed object.  This study aims to investigate the effect of various infill densities on mechanical and fire properties of polylactic acid (PLA) composites produced by FDM 3D-printing technology. PLA composites of five different infill densities were 3D-printed: 20%, 40%, 60%, 80% and 100%. The samples for all tests were designed in AutoCAD and then imported into the slicing software, Ultimaker Cura. The 3D-printer used for printing was the Ultimaker S3 which uses FDM technology. To test the fire and mechanical behavior of 3D-printed PLA composites three tests were conducted: cone calorimeter test, tensile test and UL-94 flammability test. The cone calorimeter testing was done using the incident radiation of 35 kW/m2. The results showed that the trend of HHR curves of all infill densities are akin to each other, though the peak heat release rate and total heat released increases with higher infill density. Time to ignition was also longer for samples with higher infill density. Tensile testing was conducted according to the ASTM D638 standard. The results showed that with increasing infill density mechanical properties improved, with 100% infill density having the highest tensile strength (58.15 MPa) and elastic modulus (1472.1 MPa). From the UL-94 test results no difference in flammability could be observed. Every sample had no rating, which implies that PLA specimens of all infill densities are very flammable, with long afterflame and heavy flammable dripping. The study concludes that among the examined infill densities, no ideal percentage of infill density could be found. Requirements based on application will determine what infill density is most appropriate. Nevertheless, the data collected can hopefully provide a useful reference in designing and manufacturing 3D-printed PLA composites.

An isothermal calorimeter controlled by the Peltier effect has been designed and constructed in order to investigate reaction rates in solventwater mixtures. Because a thermal method was used a constant temperature environment was essential and this was achieved by using a water bath controlled to + 0.0010C. This callorinieter has been used to study the alkaline hydrolysis of methyl acetate in dimethylsulphoxide, and tetrahydrofuran - water mixtures at 15, 25 and 35 [degrees]C. The results of other investigations on similar reactions have been reviewed and an attempt has been made to correlate the electrostatic theories of Laidler and Eyring, and Amis and jaffe with these results. Finally, because it appears that specific solvent interactions play a major part in the reaction rates the role of water in the reaction mechanism has been examined. A mechanistic explanation has been proposed in order to correlate the rate of reaction with the composition of water-solvent mixtures which justifies the Laidler and Eyring treatment of solvent effects on ion-molecule reactions. / Bradford University

In recent years, interest in sustainability and being environmentally friendly has increased. Wood is a durable and renewable building material, which is becoming more common in the constructions industry. In 2002, the government in Sweden adopted a national strategy to promote an increased use of wood in buildings. However, the usage of wood in construction has a potential risk – wood is ignitable and has fire-spreading properties.  The aim of this project was to investigate whether a ZnO coating can reduce the risk of ignition on wooden surfaces exposed to a radiative heat source, focusing on the time to ignition of the wood. ZnO possess a wide combination of physical properties, such as ability to reflect infrared radiation and being thermally stable at extremely high temperatures. The study has been carried out through a literature review and laboratory experiments. In the laboratory experiments, a cone calorimeter was used and the tests were performed according to ISO 5660-1. In the cone calorimeter, two different amounts of ZnO applied to the wood surface were tested, 0.5 and 1 g ZnO per dm2 and an untreated piece of wood as a reference. The test was carried out in three different heat fluxes: 20, 35 and 50 kWm-2. After completed tests, the change in the wood’s morphology was examined in a scanning electron microscopy (SEM). The result shows that an application of ZnO on a wooden surface significantly increases the time to ignition for the wood. An application of 0.5 g ZnO per dm2increased the time to ignition by 26-33 % for the three different heat fluxes. On the other hand, 1 g of ZnO per dm2 created an increase of 37-40 %. The trend of the increase of time to ignition was similar for all heat fluxes. The result showed no clear tendency that the smoke production rate was reduced with the application of ZnO. The heat release rate was not affected by the addition of ZnO, which was expected because ZnO delays the time to ignition, but once it catches fire, the wood burns. The SEM images before and after combustion showed that there is no change in the morphology of ZnO, although some ZnO has agglomerated but remains intact after combustion. The conclusion of this study is that ZnO has the potential to protect wood from fireby increasing the time to ignition. But when the wood has ignited, there is no clear tendency for ZnO to affect the growth of the fire. The study has shown that in the future ZnO could be applied to a wooden surface to reduce the risk of fire ignition. Further studies are required to find effective methods to implement the usage of ZnO, as applying ZnO on vertical wooden surfaces.

No description available.

Experiments were initiated to design and construct a respiratory apparatus for equine based on the indirect, open circuit method of calorimetry. The face mask, of light plexiglass, fit over the muzzle of the animal and was secured to the head, via a modified halter. Six one-way rubber inhalation valves were located along the lower portion of the mask permitting the animal to inspire atmospheric air. Four one-way rubber exhalation valves were situated in the false bottom of the mask. When the animal expired, the inhalation valves were forced shut and the exhalation valves were forced open, thus channeling the expired gas out of the mask. A series of flow meters, pumps, drying columns and storage containers were connected to the mask. Aliquots of expired gases were taken and analyzed for carbon dioxide and oxygen content to determine RQ and to calculate heat production values. All values were recorded at standard temperature, pressure and density. Three different diets were fed to equine in an attempt to alter the RQ: two ponies were first fed alfalfa-grass hay (Diet 1), then cracked corn and hay (Diet 2) was fed to 3 ponies and finally a commercial 18% protein grain mix and hay (Diet 3) was fed to the 3 ponies. Consumption problems occurred on some diets. Mean RQ's were .995 for Diet 1, 1.08 for Diet 2 and .956 for Diet 3. Mean heat production values were 2133.04, 2030.00 and 1727.23 kcal/kg feed/day for the alfalfa-grass hay, cracked corn and alfalfa grass-hay diet, and commercial grain mix and alfalfa-grass hay diet, respectively. / M.S.

Green infrastructure, including green roofs and urban vegetation, offers numerous benefits but also presents fire safety risks. Currently, there are no specific regulations in Sweden addressing the fire safety risks associated with green roofs.  Therefore, the aim of this study is to investigate the fire resistance of low-growing plants and their potential to mitigate these fire safety risks. A total of ten different plant types are analyzed, with four classified as fire-resistant and four as fire-prone based on their characteristics. The study also incorporates a 17-day dry period to assess the impact of moisture on the ignitability of the plants. By using a cone calorimeter, the plants' fire safety, their contribution to fires, and their ability to produce carbon monoxide are analyzed. For an overall assessment of fire safety, the Fire Growth Rate (FIGRA) and Fire performance index (FPI) are calculated for each plant.  The conclusions reveal that plants like Sempervivum species and chives exhibit superior moisture retention and fire safety characteristics, including low heat release rates, minimal smoke production, and effective heat capacity.  The disparity between FPI and FIGRA values indicates better flame-retardant abilities of the material, where Sempervivum species, chives, and Saxifraga Arendsii show the best values. These findings emphasize the significance of meticulous plant selection and maintenance to mitigate fire risks in both natural and urban environments. It’s essential to acknowledge that even fire-resistant plants necessitate regular maintenance, such as the removal of dead material and watering during extended dry periods, as fire resistance does not equate to fireproof.  Proposed future work entails a deeper exploration of the chemical properties and morphology of the plants to enhance our understanding of their fire resistance mechanisms. Additionally, compiling data on recommended plants for green roof installations from a fire safety perspective could aid in urban planning and vegetation management. / Grön infrastruktur, inklusive gröna tak och stadsväxtlighet, erbjuder många fördelar men innebär också brandsäkerhetsrisker. För närvarande finns det inga specifika regler i Sverige som behandlar brandsäkerhetsriskerna med gröna tak.  Därför är syftet med denna studie att undersöka brandmotståndet hos lågväxande växter och deras potential att minska dessa brandsäkerhetsrisker. Totalt analyseras tio olika växttyper, varav fyra klassificeras som brandbeständiga och fyra som brandbenägna baserat på deras egenskaper. Studien inkluderar även en simulering av en 17 dagar lång torrperiod för att bedöma fuktighetens påverkan på växternas antändbarhet. Genom användning av en konkalorimeter analyseras växternas brandsäkerhet, deras bidrag till bränder och deras förmåga att producera kolmonoxid. För en övergripande bedömning av brandsäkerheten beräknas brandspridningshastighet (FIGRA) och brandskyddsindex (FPI) för varje växt. Slutsatserna avslöjar att växter som Sempervivum-arter och gräslök uppvisar överlägsen förmågan att behålla fukt och brandsäkerhetsegenskaper, inklusive låga värden av värmeavgivningshastighet, minimal rökproduktion och effektiv värmekapacitet.   Skillnaderna mellan FPI- och FIGRA-värdena indikerar bättre flamskyddande förmåga hos materialet, där Sempervivum-arter, gräslök och Saxifraga Arendsii visar de bästa värdena. Dessa resultat understryker vikten av noggrann växtval och underhåll för att minska brandriskerna både i naturliga och urbana miljöer. Det är viktigt att förstå att även brandbeständiga växter kräver regelbunden skötsel, såsom borttagning av dött material och bevattning under långa torrperioder, eftersom brandbeständighet inte innebär att något är helt brandsäkert.   Föreslaget framtida arbete innefattar en djupare utforskning av växternas kemiska egenskaper och morfologi för att förbättra vår förståelse av deras brandsäkerhetsmekanismer. Dessutom kan sammanställning av data om rekommenderade växter för gröna takinstallationer utifrån ett brandsäkerhetsperspektiv underlätta för stadsplanering och vegetationshantering.

Après une description du LHC, de l'expérience Atlas et des systèmes calorimétriques à argon liquide, cette thèse montrera une étude qui vise à valider la simulation des gerbes électromagnétiques en utilisant des muons cosmiques. Nous discuterons ensuite de la reconstruction des pions neutres et de la cartographie de la matière dans le trajectographe interne en utilisant des photons convertis avec les premières données. Pour finir, nous présenterons les résultats obtenus concernant la recherche du boson de Higgs dans le canal H->ZZ->4l avec les données 2011 et une énergie √s=7TeV dans le centre de masse. / After a description of the LHC, the ATLAS experiment and the liquid argon calorimeter system, this thesis will show a study to validate the simulation of electromagnetic showers using cosmic muons. Then, we will discuss about neutral pion reconstruction and about the material mapping of the inner tracker using converted photons with the first data. Finally, we will present the results concerning the search for the Higgs boson in the H-> ZZ-> 4l channel with the 2011 data and a energy √s = 7TeV.