京都大学 / 新制・課程博士 / 博士(理学) / 甲第24171号 / 理博第4862号 / 新制||理||1695(附属図書館) / 京都大学大学院理学研究科地球惑星科学専攻 / (主査)准教授 西村 卓也, 教授 宮﨑 真一, 准教授 深畑 幸俊 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

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The Ministry of Environment and Climate Change establishes design criteria for the sizing of Low Impact Development (LID) practices in the province of Ontario. The current sizing standards are based on the concept of the 90th percentile storm and require LIDs to provide enough storage capacity to store catchment runoff from a 25 mm rainfall event. The notion of 90th percentile storm means that 90% of all rainfall events have event volumes below a 25 mm rainfall event. This research examines the performance and cost of infiltration trenches and bioretention cells sized for alternative sizing standards ranging from 5–50 mm. Analytical probabilistic equations are used to determine the runoff reduction rates of infiltration trenches and bioretention cells, while the Sustainable Technologies Evaluation Program (STEP)’s LID Practices Costing Tool is used to estimate the overall cost of each LID. The costs are used to create a ratio denoted the fraction of maximum cost by dividing each cost by the cost of the 50 mm sized LID to receive a unitless ratio. This ratio is compared with the runoff reduction rates of both LIDs. Four different catchment sizes and various soil types are included to broaden the scope of the analysis and make the conclusions more dependable. Results indicate that the current sizing standard of 25 mm is probably too high and not cost-effective. In fact, depending on the type of soil and LID, little increase in performance occurs while there is a large increase in cost. A new methodology is proposed for setting sizing criteria for infiltration trenches and bioretention cells which focuses on achieving a desired capture efficiency instead of a required volume of rainfall. The method proposes using the capture efficiency, fraction of maximum cost and sizing criteria to determine what value is an economically more justifiable sizing standard based on individual catchment size and soil type. Use of the analytical probabilistic approach allows for the capture efficiency to be easily calculated and provides better sizing targets on a case by case basis. Recommending a specific capture efficiency can be more uniformly applied LID design in any soil conditions or any catchment size. This can reduce government spending when building LIDs and greatly reduce the possibility of over-design. / Thesis / Master of Applied Science (MASc)

The emergence of static warfare on the Western Front in late 1914, encouraged the reinvention of devices associated with siege warfare and the invention of hitherto unknown munitions. These munitions included hand and rifle grenades and trench mortars and their ammunition. At the outbreak of war, the British effectively possessed none of these devices and lacked an infrastructure by which they could be quickly designed, manufactured and supplied to the BEF. The British met this challenge with considerable success and the subsequent proliferation of trench warfare munitions had profound consequences for the evolution of British tactics on the Western Front. This thesis examines the processes by which these devices were invented, developed into manufacturable devices and supplied to the BEF. It considers their novelty in respect to similar devices from the American Civil War and the Russo-Japanese War. It looks at how their technical evolution affected tactical developments. The thesis discusses the relationship between the technical characteristics of these devices and the evolution of their tactical employment on the Western Front. It also considers how the characteristics of certain munitions, such as the Stokes mortar and the Mills grenade, directly effected tactics. It argues that the tactical employment of these munitions was dependent upon their functionality, utility and reliability. The present thesis provides a different model of trench warfare conducted by the British during the First World War and thereby demonstrates the significance of the novel munitions under discussion and the role they played in changing infantry warfare. This thesis also provides a different view of the Ministry of Munitions from that usually offered and argues that certain aspects of the Ministry’s role in providing the BEF with munitions has been overstated by virtue of its having underplayed the work of the War Office, while overlooking that conducted by the Royal Engineers in France.

We report and discuss the performance of an enhancement mode n-channel pseudo-vertical GaN metal oxide semiconductor field effect transistor (MOSFET). The trench gate structure of the MOSFET is uniformly covered with an Al₂O₃ dielectric and TiN electrode material, both deposited by atomic layer deposition (ALD). Normally-off device operation is demonstrated in the transfer characteristics. Special attention is given to the estimation of the active acceptor concentration in the Mg doped body layer of the device, which is crucial for the prediction of the threshold voltage in terms of device design. A method to estimate the electrically active dopant concentration by applying a body bias is presented. The method can be used for both pseudo-vertical and truly vertical devices. Since it does not depend on fixed charges near the channel region, this method is advantageous compared to the estimation of the active doping concentration from the absolute value of the threshold voltage.

名古屋大学年代測定総合研究センターシンポジウム報告

More and more electronic products, like battery chargers and power supplies, as well as applications in telecommunications and automotive electronics are based on System-on-Chip solutions, where signal processing and power devices are integrated on the same chip. The integration of different functional units offers many advantages in terms of reliability, reduced power consumption, weight and space reduction, leading to products with better performance at a hopefully lower price. This thesis focuses on the integration of vertical high-voltage double-diffused MOS transistors (DMOSFETs) on Silicon-on-Insulator (SOI) substrates. MOSFETs possess a number of features which makes them indispensable for Power Integrated Circuits (PICs): high switching speed, high efficiency, and simple drive circuits. SOI substrates combined with trench technology is superior to traditional Junction Isolation (JI) techniques in terms of cross-talk and leakage currents. Vertical DMOS transistors on SOI have been manufactured and characterized, and an analytical model for their on-resistance is presented. A description of self-heating and operation at elevated temperatures is included. Furthermore, the switching dynamics of these components is investigated by means of device simulations with the result that the dissipated power during unclamped inductive switching tests is reduced substantially compared to bulk vertical DMOSFETs. A large number of defects is created in the device layer if the trenches are exposed to high temperatures during processing. A new fabrication process with back-end trench formation is introduced in order to minimize defect generation. In addition, a model for the capacitive coupling between trench-isolated structures is developed.