Shaken baby syndrome is a clinicopathologic syndrome characterized by a triad of findings: subdural hemorrhage, retinal hemorrhage and axonal injury. Although shaking is widely believed to cause the triad, it is not yet entirely clear if shaking without head impact can produce the triad. Initial attempts to test the effect of shaking in mouse pups were unsuccessful as neither controlled continuous vibration nor pulse acceleration caused any of the components of the triad. With no other convenient modeling system available, a pilot study with three adult subhuman primates was conducted. Although a conclusive statement cannot be made, manual shaking did not immediately cause hemorrhagic injuries to the primates’ brains and eyes. Future studies should test for delayed development of axonal injury. In addition, a comparative anatomical study should also be conducted to test the validity of the adult primate as a model system for human infant injuries.

Shaken baby syndrome is a clinicopathologic syndrome characterized by a triad of findings: subdural hemorrhage, retinal hemorrhage and axonal injury. Although shaking is widely believed to cause the triad, it is not yet entirely clear if shaking without head impact can produce the triad. Initial attempts to test the effect of shaking in mouse pups were unsuccessful as neither controlled continuous vibration nor pulse acceleration caused any of the components of the triad. With no other convenient modeling system available, a pilot study with three adult subhuman primates was conducted. Although a conclusive statement cannot be made, manual shaking did not immediately cause hemorrhagic injuries to the primates’ brains and eyes. Future studies should test for delayed development of axonal injury. In addition, a comparative anatomical study should also be conducted to test the validity of the adult primate as a model system for human infant injuries.

The goal of the project is to develop, build, and test a modular steel structure that can be tested on an educational shaking table to demonstrate structural dynamic and earthquake engineering principles. The advantage of the structure is that it can be tested into its non-linear range and yielded parts can easily be replaced for subsequent tests. The steel modular structure represents a multi-story moment resisting frame and is comprised of sheet metal beams and columns bolted to “rigid” steel angles. This structure is tested on a unidirectional shaking table, viz. “Quanser Shake Table II”. The structure is designed to achieve a specific mode of failure through non-linear analysis. A non-linear pushover analysis is carried out to determine stiffness and strength of the structure as well as potential hinge locations. Eigen-value analysis is undertaken to determine all the natural periods and frequencies that will help in understanding its dynamic response. The structure is analyzed and tested for various ground motions to study the effects of an earthquake on a multi-storied frame. Educational modules provide a set of experiments that can be easily performed on the test structure. / text

L’industrialisation de la production des conducteurs utilisant les cuprates à haute température de transition pendant les deux dernières décennies offre aujourd’hui la possibilité de nouveaux développements dans le domaine du magnétisme supraconducteur. En particulier, nous nous intéressons ici aux applications des rubans supraconducteurs REBCO. Ceux-ci font partie des rares candidats disponibles à l’heure actuelle capables de fonctionner sous des inductions supérieures à 20 T aux températures de cryogénie classique (4,2 K), ce qui les rend quasiment incontournables dans le contexte des applications haut-champ. Parallèlement, leurs températures critiques élevées apportent également la possibilité de nouvelles conceptions d’aimants pouvant fonctionner à des températures allant jusqu’à 80 K environ. Ceci ouvre notamment la porte à de nouvelles options de cryogénie moins coûteuses, comme le refroidissement par azote liquide. Néanmoins, la mise en œuvre des rubans REBCO à l’intérieur de nouveaux aimants supraconducteurs se heurte dans certains cas au problème posé par les courants d’écrantages. Ce terme désigne les supercourants induits dans le matériau supraconducteur en réponse au champ extérieur. Ces courants parasites engendrent alors des perturbations sur le champ magnétique total produit par l’aimant : réduction de son amplitude, distorsions spatiales et instabilités temporelles. Ces multiples effets entrent généralement en collision avec les exigences sur la qualité de champ produite. Ainsi, comprendre le phénomène des courants d’écrantages, être capable de prédire sa dynamique et, idéalement, disposer de solutions afin d’y remédier, sont des tâches cruciales pour assurer la réussite des futurs projets d’aimants supraconducteurs REBCO. Cette thèse propose des éléments de réponse vis-à-vis de cette problématique. Le phénomène de courants d’écrantages y est tout d’abord approché de manière expérimentale au travers de la mesure de ses effets perturbateurs sur le champ magnétique de petits aimants tests REBCO. Les données expérimentales récoltées sont ensuite employées pour étayer le développement d’un modèle numérique de simulation magnétodynamique sous l’environnement open-source GetDP. Ce modèle est par ailleurs mis à l’essai avec de bons résultats dans le cas du dipôle 5,4 T EuCARD du CERN. Enfin dans une dernière partie, une investigation expérimentale est menée sur deux techniques capables de réduire, voire de supprimer intégralement, les impacts négatifs des courants d’écrantages sur le champ des aimants REBCO : le vortex shaking et l’overshoot en courant. Au travers de ces développements, cette thèse entend fournir aux concepteurs de futurs aimants supraconducteurs REBCO des moyens d’anticiper et de traiter les problèmes posés par les courants d’écrantages. / The industrialization of the production of high-transition temperature, cuprate-based conductors during the last two decades brings nowadays the possibility of new developments in the field of superconducting magnetism. In particular, we are interested here in the applications of superconducting REBCO tapes. Those belong to the few currently available candidates that are able to operate under magnetic induction above 20 T at classical cryogenic temperature (4.2 K), what makes them almost unavoidable in the scope of high-field applications. Besides, their high critical temperatures also bring the possibility for new magnet designs capable to operate up to temperatures of about 80 K. This notably opens the door to new, less expensive, cryogenic design options, like liquid nitrogen cooling.However, the practical implementation of REBCO tapes inside new superconducting magnets encounters a problem posed by screening currents. The latter term designates the supercurrents that are induced in the superconducting material in response to an external field. These parasitic currents then give rise to perturbations in the total magnetic field generated by the magnet: lowering of its magnitude, spatial distortions and time instabilities. Those various effects collide most of the time with the requirements on the produced field quality. Thus, understanding the phenomenon of screening currents, being able to predict its dynamic and, ideally, having of solutions to remedy this issue, are crucial tasks to ensure the success of future REBCO superconducting magnet projects.This Ph.D. work suggests some elements of answer with regard to this problematic. The phenomenon of screening currents is first approached experimentally, through the measurement of its disruptive effects of the magnetic field generated by small REBCO tests magnets. The experimental data gathered are then used to support the development of a numerical model for magnetodynamic simulations in the framework of the open-source environment GetDP. This model is furthermore tested with satisfactory results on the scenario of the 5.4 T EuCARD dipole developed by CERN. Finally, in a last section, an experimental investigation is conducted on two techniques capable at reducing, or even entirely suppressing, the negative impacts of the screening currents on the field of REBCO magnets: the vortex shaking and current overshoot.Across these developments, this Ph.D. work aims at providing the designers of future REBCO superconducting magnets with tools to anticipate and handle the issues caused by the screening currents.

De manière à respecter les normes européennes en matière d’émission de gaz polluants, les constructeurs automobiles pratiquent le downsizing. Cette pratique consiste en une réduction de la cylindrée des moteurs tout en maintenant un bon niveau de performance. Il s’en suit des puissances spécifiques moteur importantes, l’objectif cible étant de l’ordre de 100 kW/l. Pour de telles puissances, les températures atteintes au niveau des pistons sont élevées, ce qui pose alors le problème de leur tenue thermomécanique. Le refroidissement du piston devient donc un acteur important de la fiabilité du moteur. Le procédé le plus répandu actuellement est le refroidissement par jet d’huile. Le piston est alors refroidi par un écoulement turbulent diphasique incompressible (Air/Huile) dans un environnement mobile. Il s’agit de phénomènes physiques complexes qui sont pour l’instant mal connus. L’optimisation du refroidissement nécessitant une bonne compréhension des phénomènes physiques concernés, nous nous proposons dans ce mémoire de le modéliser au moyen du modèle 1-Fluide diphasique couplé à l’équation de l’énergie. / The present work aims at studying the cooling system used in cars engine to ensure piston thermo mechanical resistance by numerical simulation. Most of actual engines use an oil jet cooling system coupled with 'cocktail shaking' to extract heat from piston. This cooling method brings into play a two-phase incompressible turbulent flow in a mobile environment, due to motion of pistons in the cylinder. The need today for more effective cooling of pistons involves an accurate understanding of the physical mechanisms which are concerned. Modeling could be a good way to achieve it. The idea is to support the engine design process to account for advanced technologies to improve turbine or engine performances, less fuel burn and green house gases. In the present work, a numerical model dedicated to the simulation at small scale of oil/air two-phase flows and related heat transfers is proposed to characterize the cooling of engine elements under fragmented jet impact.

京都大学 / 新制・課程博士 / 博士(工学) / 甲第23485号 / 工博第4897号 / 新制||工||1765(附属図書館) / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 渦岡 良介, 教授 肥後 陽介, 准教授 PIPATPONGSA Thirapong / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

This research involves the study of a one- and two-cylinder convertible reciprocating Freon compressor for air conditioning or refrigeration purposes. The main concern is the reduction of the vibration (noise) caused during the operation of the compressor. Vibration is a main concern when the compressor is shifted from the one-cylinder operation to the two-cylinder operation mode and the reverse of this shift. The objectives for this research are (1) to investigate the shaking force due to the reciprocating mass at high frequencies, which are up to 4600 Hz (80w) in this research; (2) to determine the dominant force for compressor vibration among the three possible sources of shaking force due to reciprocating mass, impact forces due to clearance at the connecting rod - piston joint, and the z-axis force from the motor torque due to the rotor's conductor rods being skewed at an angle; (3) to minimize the difference in change of kinetic energies when switching between the one- and two-cylinder operating modes of the compressor. The properties of the vibration in one- and two-cylinder operation have been studied and results have been analyzed in terms of kinetic energies generated in different setting of operation of the compressor. Dynamic simulation for the impact force is computed using SIMULINK. The Z-axis force due to the motor is computed. Results indicated that shaking force due to the reciprocating mass is the dominant force for only the first two harmonics (w, 2w). An optimization routine based on Hooke and Jeeves pattern search method is developed and an optimized setting of angle, force, and torque for balancing of the crankshaft to achieve objective (3) is determined. / Master of Science

This research employs a deterministic seismic risk assessment methodology to assess the potential damage and loss at meshblock level in the Christchurch CBD and Mount Pleasant primarily due to building damage caused by earthquake ground shaking. Expected losses in terms of dollar value and casualties are calculated for two earthquake scenarios. Findings are based on: (1) data describing the earthquake ground shaking and microzonation effects; (2) an inventory of buildings by value, floor area, replacement value, occupancy and age; (3) damage ratios defining the performance of buildings as a function of earthquake intensity; (4) daytime and night-time population distribution data and (5) casualty functions defining casualty risk as a function of building damage. A GIS serves as a platform for collecting, storing and analyzing the original and the derived data. It also allows for easy display of input and output data, providing a critical functionality for communication of outcomes. The results of this study suggest that economic losses due to building damage in the Christchurch CBD and Mount Pleasant will possibly be in the order of $5.6 and $35.3 million in a magnitude 8.0 Alpine fault earthquake and a magnitude 7.0 Ashley fault earthquake respectively. Damage to non-residential buildings constitutes the vast majority of the economic loss. Casualty numbers are expected to be between 0 and 10.

In this research, the dynamic behavior of a seismic isolation system composed of high strength geotextile placed over an ultra-high molecular weight polyethylene (UHMWPE) geomembrane (together called as composite liner) beneath the structure is investigated experimentally. The results of the shaking table experiments which were performed on model structures both under harmonic and modified earthquake motions with and without the seismic isolation (composite liner system), are presented in the thesis. The main focus is given on the potential improvement obtained by use of the composite liner system as compared to the unisolated cases. Based on the performed experiments, it is observed that the utilization of composite liner system provides significant reduction in the accelerations and interstorey drift ratios of structures under harmonic motions while signifant drop is obtained in the spectral accelerations under earthquake motions which provide noticeable improvement in the durability of structures under dynamic effects at the expense of increased translational displacements.

Vertical inclusions of expanded polystyrene (EPS) placed behind rigid retaining walls were investigated as geofoam seismic buffers to reduce earthquake-induced loads. A numerical model was developed using the program FLAC and the model validated against 1-g shaking table test results of EPS geofoam seismic buffer models. Two constitutive models for the component materials were examined: elastic-perfectly plastic with Mohr-Coulomb (M-C) failure criterion and non-linear hysteresis damping model with equivalent linear method (ELM) approach. It was judged that the M-C model was sufficiently accurate for practical purposes. The mechanical property of interest to attenuate dynamic loads using a seismic buffer was the buffer stiffness defined as K = E/t (E = buffer elastic modulus, t = buffer thickness). For the range of parameters investigated in this study, K ≤ 50 MN/m3 was observed to be the practical range for the optimal design of these systems. Parametric numerical analyses were performed to generate design charts that can be used for the preliminary design of these systems. A new high capacity shaking table facility was constructed at RMC that can be used to study the seismic performance of earth structures. Reduced-scale models of geosynthetic reinforced soil (GRS) walls were built on this shaking table and then subjected to simulated earthquake loading conditions. In some shaking table tests, combined use of EPS geofoam and horizontal geosynthetic reinforcement layers was investigated. Numerical models were developed using program FLAC together with ELM and M-C constitutive models. Physical and numerical results were compared against predicted values using analysis methods found in the journal literature and in current North American design guidelines. The comparison shows that current Mononobe-Okabe (M-O) based analysis methods could not consistently satisfactorily predict measured reinforcement connection load distributions at all elevations under both static and dynamic loading conditions. The results from GRS model wall tests with combined EPS geofoam and geosynthetic reinforcement layers show that the inclusion of a EPS geofoam layer behind the GRS wall face can reduce earth loads acting on the wall facing to values well below those recorded for conventional GRS wall model configurations. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2011-04-28 16:56:57.084