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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Response of the PANDA electromagnetic calorimeter to photons with energies below 100 MeV

Marcks von Würtemberg, Klas January 2011 (has links)
Characteristics of the electromagnetic calorimeter of PANDA (anti-Proton ANnihilations at DArmstadt), one of the key experiments at FAIR, have been measured at the tagged photon beam facility at MAX-lab for 61 energies in the range 12-63 MeV. The tested detector array consisted of 5x5 PbWO4 (lead tungstate) crystals designed for the forward end-cap. The array was cooled to -25 ºC and read out with conventional photomultiplier tubes. The measured energy resolution, σ/E, (for example 6 % at 20 MeV) shows that the current design meets the criterion of PANDA. The array is now ready to be equipped with vacuum phototriods designed for the forward end-cap.         As a part of the experiment, characteristics of the tagging spectrometer at MAX-lab were measured. This revealed a lowered performance in terms of resolution for low energies. A discrepancy between the nominal and the measured tagged energies was also discovered. Possible explanations to these observations are presented.
32

Controlling Object Heat Release Rate using Geometrical Features

Kraft, Stefan Marc 08 June 2017 (has links)
An experimental study was conducted to determine the effect of complex geometries on the burning rate of materials made using additive manufacturing. Controlling heat release rate has applicability in limiting fire hazards as well as for designing fuels for optimal burning rate. The burning rate of a structure is a function of the material properties as well as the airflow through it, which is dictated by the geometry. This burning rate is generally proportional to the porosity for objects in which the flow is limited by the path constriction. The relations between porosity and burning rate are well studied for wood cribs, which are layers of wood sticks. Crib and other objects with various geometric features were constructed of ABS plastic and coal powder using additive manufacturing processes. A cone calorimeter using oxygen calorimetry was used to measure the heat release rate of the crib specimens. Within the flow limited burning regime, the burning rate of an object is proportional to the porosity factor. Porosity factors calculated from a 1-D theoretical burn rate model as well as from two empirical models were found to correlate the heat release rate results for the crib samples. The heat release rate results of the complex geometries generally correlated to the same porosity factor; however, the model was modified to account for differences between regularly shaped cribs and objects with different sized flow areas. Using the empirical models provides good correlation for the crib burning data and gives a clearer delineation between the flow-limited and surface area controlled regimes. / Master of Science
33

The Development of High-Throughput and Miniaturized Differential Scanning Calorimeter for Thermodynamic Study of Bio-Molecules

Yu, Shifeng 19 February 2019 (has links)
Biomolecular interactions are fundamentally important for a wide variety of biological processes. Understanding the temperature dependence of biomolecular interactions is hence critical for applications in fundamental sciences and drug discovery. Micro-Electro-Mechanical Systems (MEMS) technology holds great potential in facilitating temperature-dependent characterization of biomolecular interactions by providing on-chip microfluidic handling with drastically reduced sample consumption, and well controlled micro- or nanoscale environments in which biomolecules are effectively and efficiently manipulated and analyzed. This dissertation is focused on a high-through and miniaturized differential scanning calorimeter for thermodynamic study of bio-molecules using MEMS techniques. The dissertation firstly introduces the overall design and operation principles. This miniaturized DSC was fabricated based on a polyimide (PI) thin film. Highly temperature sensitive vanadium oxide was used as the thermistor material. A PDMS (Polydimethylsiloxane) microfluidic chamber was separately fabricated and then bonded firmly with the PI substrate by a stamp-and-stick method. Meanwhile, the micro heater design was optimized to reach better uniformity. A heating stage was constructed for fast and reliable scanning. In this study, we used syringes to deliver the 0.63 μL liquid sample into both the sample and reference chambers. All the testing processes were functionalized using the LabVIEW programs. The sensing material was also characterized. To seek a higher temperature coefficient of resistance (TCR) and less resistive behavior, explorations about various PVD (physical vapor deposition) parameters and annealing conditions were conducted for optimization. In this research, we found vanadium oxide deposited under certain conditions leads to the highest TCR value (a maximum of 2.51%/oC). To better understand the material’s property, we also did the XRD (X-ray Diffraction), SEM (Scanning electron microscope). The micro calorimeter was calibrated using a step thermal response. The time constant was around 3s, the thermal conductance was 0.6mW/K, and the sensitivity was 6.1V/W. The static power resolution of the device at equilibrium is 100 nW, corresponding to 250 nJ/K. These performances confirmed the design and material to be appropriate for both good thermal isolation and power sensitivity. We demonstrated the miniaturized DSC’s performance on several different kinds of protein samples: lysozyme, and mAb (monoclonal antibody) and a DVD IgG (double variable domain immunoglobulin G). The results were found to be reasonable by comparing it with the commercial DSC’s tests. Finally, this instrument may be ideal for incorporation into high throughput screening workflows for the relative comparison of thermal properties between large numbers of proteins when only small quantities are available. The micro-DSC has the potential to characterize the thermal stability of the protein sample with significantly higher throughput and less sample consumption, which could potentially reduce the time and cost for the drug formulation in the pharmaceutical industry. / Ph. D. / Virtually all biological phenomena depend on molecular interactions, which is either intra-molecular as protein folding/unfolding or intermolecular as in ligand binding. A basic biology problem is to understand the folding and denaturation processes of a protein: the kinetics, thermodynamics and how a protein unfolds and folds back into its native state. Both folding/unfolding and denaturation processes are associated with enthalpy changes. The thermodynamics of binding compounds helps a great deal to understand the nature and potency of such molecules and is essential in drug discovery. As a label-free and immobilization-free method, calorimetry can evaluate the Gibbs free energy, enthalpy, entropy, specific heat, and stoichiometry, and thus provides a fundamental understanding of the molecular interactions. Calorimetric systems including isothermal titration calorimeters (ITC) and differential scanning calorimeters (DSC) are the gold standard for characterizing molecular interactions. In this research, a micro DSC is developed for direct thermodynamic study of bio-molecules. Compared with the current commercial DSC, it is on a much smaller scale. It consumes much less sample and time in each DSC measurement. It can enable comprehensive high-content thermodynamics study in the early stage of drug discovery and formulation. It also enables direct, precise, and rapid evaluation of the folding and unfolding of the large biomolecules like proteins, DNAs, and enzymes without labeling or immobilization. It can also be used as a powerful tool to study the membrane proteins, which is often impractical or impossible before.
34

Design studies and sensor tests for the beam calorimeter of the ILC detector

Kuznetsova, Ekaterina 30 January 2007 (has links)
Der zukünftige Linearbeschleuniger (International Linear Collider - ILC) wird für die Teilchenforschung im Energiebereich bis zu einem Tera-Elektronenvolt (TeV scale) entwickelt. In dieser Arbeit wird der Entwurf des inneren Vorwärtsbereichs (Very Forward Region) eines Detektors füur diesen Beschleuniger beschrieben. Das Beam-Kalorimeter - eines der zwei elektromagnetischen Kalorimeter, die hier angeordnet sind - ist Gegenstand dieser Arbeit. Das Beam-Kalorimeter muss eine gute Hermetizität für hochenergetische Elektronen, Positronen und Photonen bis hinab zu sehr kleinen Polarwinkeln gewährleisten. Es dient für die schnelle Strahldiagnose und als Abschirmung des inneren Detektors gegen rückgestreute Beamstrahlungsreste und Synchrotronstrahlung. Als eine mögliche Technologie für das Beam-Kalorimeter wird eine Sandwich-Anordnung aus Diamantsensoren und Wolfram- Absorberplatten betrachtet. Es werden detaillierte Simulationen einer solchen Anordnung durchgeführt. Die Nachweiseffektivität und die Energie- sowie Winkelauflösung für elektromagnetische Schauer werden untersucht. Im Ergebnis der Simulationsrechnungen wird nachgewiesen, dass die vorgeschlagene Anordnung die Anforderungen an ein Beam-Kalorimeter erfüullt. Zusätzlich werden Untersuchungen an polykristallinem Diamantmaterial, hergestellt mittels Abscheidung aus der Dampfphase (Chemical Vapour Deposition - CVD), durchgeführt, um dessen Eigenschaften als Sensormaterial für ein Beam-Kalorimeter zu ermitteln. Die Ergebnisse der Messungen von Mustern verschiedener Hersteller werden dargestellt diskutiert. / The International Linear Collider (ILC) is being designed to explore particle physics at the TeV scale. The design of the Very Forward Region of the ILC detector is considered in the presented work. The Beam Calorimeter - one of two electromagnetic calorimeters situated there - is the subject of this thesis. The Beam Calorimeter has to provide a good hermeticity for high energy electrons, positrons and photons down to very low polar angles, serve for fast beam diagnostics and shield the inner part of the detector from backscattered beamstrahlung remnants and synchrotron radiation. As a possible technology for the Beam Calorimeter a diamond-tungsten sandwich calorimeter is considered. Detailed simulation studies are done in order to explore the suitability of the considered design for the Beam Calorimeter objectives. Detection efficiency, energy and angular resolution for electromagnetic showers are studied. At the simulation level the diamond-tungsten design is shown to match the requirements on the Beam Calorimeter performance. Studies of polycrystalline chemical vapour deposition (pCVD) diamond as a sensor material for the Beam Calorimeter are done to explore the properties of the material. Results of the measurements performed with pCVD diamond samples produced by different manufacturers are presented.
35

Novel Amine-Functionalized Phosphoryl Hydrazine Flame Retardants for Epoxy Resin Systems

Bin Sulayman, Abdulhamid January 2018 (has links)
No description available.
36

Experimental and Numerical Modeling of Heat Transfer in Wall Assemblies

2014 April 1900 (has links)
It is critical for the construction industry to ensure that new building designs and materials, including wall and floor assemblies, provide an acceptable level of fire safety. A key fire safety requirement that is specified in building codes is the minimum fire resistance rating. A manufacturer of building materials (e.g., insulation or drywall) is currently required to perform full-scale fire furnace tests in order to determine the fire resistance ratings of assemblies that use their products. Due to the cost of these tests, and the limited number of test facilities, it can be difficult to properly assess the impact of changes to individual components on the overall fire performance of an assembly during the design process. It would be advantageous to be able to use small-scale fire tests for this purpose, as these tests are relatively inexpensive to perform. One challenge in using results of small-scale fire tests to predict full-scale fire performance is the difficulty in truly representing a larger product or assembly using a small-scale test specimen. Another challenge is the lack of established methods of scaling fire test results. Cone calorimeter tests were used to measure heat transfer through small-scale specimens that are representative of generic wall assemblies for which fire resistance ratings are given in the National Building Code of Canada. Test specimens had a surface area of 111.1 mm (4.375 in.) by 111.1 mm (4.375 in.), and consisted of single or double layers of gypsum board, stone wool insulation and spruce-pine-fir (SPR) studs. As the specimens were designed to represent a one-quarter scale model of a common wall design, with studs spaced at a centre-to-centre distance of 406.4 mm (16 in.), the wood studs were made by cutting nominal 2x4 studs (38 mm by 89 mm) into 9.25 mm by 89 mm (0.375 in. by 3.5 in.) pieces. The scaled studs were then spaced at a centre-to-centre distance of 101.6 mm (4 in.). Three types of gypsum board were tested: 12.7 mm (0.5 in.) regular and lightweight gypsum board, and 15.9 mm (0.625 in.) type X gypsum board. Temperature measurements were made at various points within the specimens during 70 min exposures to an incident heat flux of 35, 50 and 75 kW/m2 using 24 AWG Type K thermocouples and an infrared thermometer. Temperature measurements made during cone calorimeter tests were compared with temperature measurements made during fire resistance tests of the same generic assemblies and the result show a very good agreement for the first 25 min of testing at the unexposed side. A one-dimensional conduction heat transfer model was developed using the finite difference method in order to predict temperatures within the small-scale wall assemblies during the cone calorimeter tests. Constant and temperature-dependent thermal properties were used in the model, in order to study the effects of changes to materials and thermal properties on fire performance. A comparison of predicted and measured temperatures during the cone calorimeter tests of the generic wall assemblies is presented in this thesis. The model had varying degrees of success in predicting temperature profiles obtained in the cone calorimeter tests. Predicted and measured times for temperatures to reach 100C and 250C on the unexposed side of the gypsum board layer closest to the cone heater were generally within 10%. There was less agreement between predicted and measured times to reach 600C at this location, and the temperature increase on the unexposed side of the test specimen. The model did not do a good job in predicting temperatures in the insulated double layer walls. Sensitivity studies show that the thermal conductivity of the gypsum board has the most significant impact on the predicted temperature.
37

Développement de compteurs à scintillation hautes performances et de très basse radioactivité pour le calorimètre du projet SuperNEMO

Chauveau, Emmanuel 18 November 2010 (has links)
SuperNEMO est un projet de détecteur de nouvelle génération pour la recherche de la décroissance double bêta sans émission de neutrinos. La technique expérimental déployée est dans la lignée du son prédécesseur NEMO3, combinant un trajectographe et un calorimètre, afin d’identifier non seulement les électrons des décroissances double bêta, mais également pour mesurer l’ensemble des composantes de bruit de fond du détecteur. Le projet vise ainsi une sensibilité de 10^26 ans sur la période du 82Se, ce qui permettrait de sonder une masse effective du neutrino de 50 meV. Pour atteindre cette sensibilité, le projet prévoit notamment de mettre en place un calorimètre composé d’un millier de compteur à scintillation de basse radioactivité, dont la résolution en énergie serait meilleure que 8 % FWHM pour des électrons de 1 MeV.Ce travail de thèse apporte une contribution importante dans les travaux de Recherche et Développements pour améliorer les performances des scintillateurs et photomultiplicateurs, et pour réduire leur radioactivité, avec notamment la conception d’un nouveau photomultiplicateur en collaboration avec Photonis. / SuperNEMO is a next generation double beta decay experiment which will extend the successful “tracko-calo” technique employed in NEMO 3. The main characteristic of this type of detector is to identify not only double beta decays, but also to mesure its own background components. The projet aims to reach a sensitivity up to 1026 years on the half-life of 82Se. One of the main challenge of the Research and Development is to achieve an unprecedented energy resolution for the electron calorimeter, better than 8 % FWHM at 1 MeV.This thesis contributes to improve scintillators and photomultiplicators performances and reduce their radioactivity, including in particular the development of a new photomultiplier in collaboration with Photonis.
38

Reaction calorimetry applied to kinetic problems : the design and construction of an isothermal calorimeter with heat compensation by the Peltier effect, and the application of the calorimeter in the study of reaction kinetics in solvent/water mixtures

Canning, R. G. January 1973 (has links)
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.
39

Performance du calorimètre à argon liquide et recherche du boson de Higgs dans son canal de désintégration H -->ZZ*->4l avec l'expérience ATLAS auprès du LHC / Performance of the liquid argon calorimeter, search and study of the Higgs boson in the channel H -> ZZ* -> 4 l with the ATLAS detector

Tiouchichine, Elodie 14 November 2014 (has links)
Les travaux de thèse effectués au sein de la collaboration ATLAS et présentés dans ce manuscrit se sont déroulés dans le contexte de la découverte d'une nouvelle particule dans la recherche du boson de Higgs du Modèle Standard au LHC. Après une introduction du cadre théorique, le LHC et le détecteur ATLAS sont présentés ainsi que leurs performances durant cette première phase de prise de données comprenant les données acquises en 2011 et 2012. Une attention particulière est portée aux calorimètres à argon liquide et au traitement de la qualité des données enregistrées par ce système. Des études de validation des données collectées durant des conditions non nominales de la haute tension des calorimètres à argon liquide ont abouti à la récupération de 2% des données collectées, les rendant ainsi disponibles pour l'analyse de physique. Ceci a un impact direct sur le canal H -> ZZ* -> 4 l où le nombre d'événements attendus est faible. Dans le but d'optimiser l'acceptance du canal de désintégration en quatre électrons, des nouveaux algorithmes de reconstruction des électrons ont été introduits en 2012, et la mesure de son efficacité est présentée. Le gain d'efficacité allant jusqu'à 7% pour les électrons de basse énergie transverse (15<E_T<20 GeV) constitue une des améliorations de l'analyse dans le canal H -> ZZ* -> 4 l qui est présentée pour les données 2012. Les méthodes d'estimation du bruit de fond réductible des canaux contenant des électrons dans l'état final ont été au centre de l'attention durant la période qui a suivi la découverte et sont particulièrement décrites. Les mesures de propriétés du boson découvert, basées sur les données de 2011 et 2012 sont présentées. / The work presented in this thesis within the ATLAS collaboration was performed in the context of the discovery of a new particle at the LHC in the search for the Standard Model Higgs boson. My contribution to the Higgs boson search is focused in the H -> ZZ* -> 4 l channel at different level, from the data taking to the physics analysis. After a theoretical introduction, the LHC and the ATLAS detector are presented as well as their performance during the 2011 and 2012 runs. A particular consideration is given to the liquid argon calorimeters and to the data quality assesment of this system. The validation of the data recorded during non-nominal high voltage conditions is presented. This study allowed to recover 2% of the data collected available for physics analyses. This has a direct impact on the H -> ZZ* -> 4 l channel were the number of signal events expected is very low. In order to optimize the acceptance of the four electrons decay channel, novel electron reconstruction algorithms were introducted in 2012. The measurement of their efficiency is presented. The efficiency gain reaching 7% for low transverse energy electrons (15<E_T<20 GeV) is one of the main improvements in the H -> ZZ* -> 4 l analysis presented using the data recorded in 2012. The reducible background estimation methods in the channels containing electrons in the final state that were of primary importance after the discovery are detailed. Finally, the measurement of the new boson properties are presented based on the 2011 and the 2012 recorded data.
40

Experimental Analysis of Positive Displacement Compressors for Refrigerator Freezer and Air Conditioning Application

Cai S Rohleder (6251672) 14 May 2019 (has links)
<div>Vapor compression cycles are the most common method used to provide cooling to environments. In the residential area, refrigerator/freezers as well as air conditioners/heat pumps almost exclusively use vapor compression cycles. The driving force behind a vapor compression cycle is the compressor, where a variety of compressor types are used in the same application. While reciprocating compressors are found in the majority of refrigerator/freezers, scroll compressors are predominantly used in residential air conditioners. Yet other compressors have emerged as replacements due to increased efficiency. A R134a oil-free prototype scroll compressor and a R134a reciprocating compressor are operated in a hot-gas bypass test stand under refrigerator/freezer conditions to compare performance. Additionally, a R407C scroll compressor and a R410A rotary compressor are operated in a compressor calorimeter under air conditioning/heat pump conditions to compare performance. Experimental results show that the reciprocating compressor far outperforms the prototype scroll compressor in the refrigerator/freezer application, while the performance between the scroll and rotary compressors are almost equal in the air conditioning application.</div><div>Pressure fluctuation at compressor discharge is also measured in the compressor calorimeter to determine feasibility of applying a novel muffling design to air conditioning compressors, although it was found that traditional muffling methods currently used are effective to a degree such that this new method is unwarranted. Data from the compressor calorimeter is also used to investigate the accuracy of the AHRI 540 10-Coefficient Correlation compressor map in predicting performance both inside and outside the tested operating conditions. The AHRI 10-Coefficient Correlation achieves high accuracy inside tested operating conditions but is inept in extrapolating performance, where other map correlations are more accurate.</div>

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