Historically humans have settled in river valleys, which has made flooding a natural hazard for human communities. This is also the situation in the valley of Cochabamba, which is frequently affected by floods. Therefore it is of high relevance to assess and manage the flood risk in order to reduce the impact in the affected areas. For this purpose hydraulic simulations were performed with the two-dimensional model Iber. The study area includes 17 kilometers of the main river, Rio Rocha, and its tributaries. The data used in the project was elevation data of high resolution and computed hydrographs. Field work and sensitivity analysis were performed to evaluate the result. The model was used to describe the dynamics of the Rio Rocha and its tributaries during flooding, such as flow path and water levels. The simulations showed that flooding mainly occurs in the tributaries and at eleven other sites without a clear riverbank. Most of the area affected by flooding is agricultural land, but also residential areas and infrastructure were also at risk. The flood duration shown to be longest for agricultural land, which can lead to major crop damage due to anoxic condition. Even though a smaller part of the affected area is residential land, the urbanization in this area is predicted to increase and more land may be settled in the near future.This thesis, along with other studies, highlights the importance of high resolution mesh to perform a hydraulic simulation with a two-dimensional model and the need of data to validate the result.

The development of low form factor flight controls is driven by the benefits of reducing the installed volume of the control device and/or minimising the change in external geometry, with particular application to flight control of low observable aircraft. For this work, the term "low form factor" does not refer to the aspect ratio of the control device rather the overall installed volume. This thesis compares the use of low form factor geometric and fluid devices on a NACA 0015 aerofoil section through two-dimensional numerical analysis and low speed wind tunnel experiments. The geometric spoiler is implemented as a small (boundary layer scale) variable height tab oriented normal to the local surface, referred to as a Micro Geometric Spoiler (MiGS). The fluidic spoiler is implemented as an air jet tangential to the local surface acting in the forward direction, referred to as a Counter-Flow Fluidic Spoiler (CFFS). Two chordwise spoiler locations were considered: 0.35c and 0.65c. Numerical analysis was undertaken using a commercial CFD code using an unsteady solver and k-omega shear-stress-transport turbulence model. Experimental forces and moments were measured via an overhead force balance, integrated surface pressures and pressure wake survey. Device performance is assessed against the magnitude of control achievable compared to macro scale spoilers and trailing edge controls (effectiveness), the ratio of aerodynamic output to control input (efficiency or gain), the shape of control response curve (linearity), and the degree of control cross coupling. Results show that the MiG and CFF spoilers work by a similar mechanism based on inducing flow separation that increases the pressure ahead of the spoiler and reduces the pressure downstream. Increasing control input increases drag and reduces lift, however the change in pitching moment is dependent on chordwise location. Chordwise location has a significant effect on effectiveness, efficiency, linearity and separability. Forward MiGS location gives the largest drag gain however the control response is strongly nonlinear with angle of attack and there is a significant undesirable coupling of drag with pitching moment. Aft MiGS location significantly improves control linearity and reduces pitching moment coupling however the drag gain is much reduced. For the CFFS, the control linearity with respect to control input and angle of attack is good for both forward and aft locations, with the aft location giving the largest gain for lift and drag. The control response trends predicted from numerical analysis are good, however a calibration factor of around ½ has to be applied to the control input momentum to match the experimentally observed gains. Furthermore numerical control drag polars under predict the change in lift with change in drag at low blowing rates. Through the use of a CFFS device on both the upper and lower surfaces of a wing section it is possible to generate control drag inputs fully decoupled from both lift and pitching moment, thus potentially simplifying device control law implementation within an integrated yaw control system.

Clara Wieck Schumann’s 1836 Piano Concerto Op. 7 represents an era of radical formal experimentation in the early nineteenth century. As such, critics including Robert Schumann questioned its unity, thus prompting late twentieth-century scholars to reassess both its departures from tradition and its cohesive mechanisms. I propose that the concerto’s formal innovations are a result of Wieck’s decision to construct a tripartite work from her autonomous Concertsatz, which became the Finale after the addition of a first and second movement. This study uses William Caplin’s theory of formal functions and Steven Vande Moortele’s theory of two-dimensional sonata form to examine how Wieck complemented the independent Finale with a formally divergent first movement, which facilitates the projection of an overarching sonata form spanning the entire work. In doing so, this study produces a model to assess the concerto’s internal logic.

In this paper, we use the forward recursion BCJR algorithm to estimate the symmetric information rate for Two Dimensional Magnetic Recording (TDMR) channels. In particular, we consider a TDMR read/write channel whose all components, including recording medium, write and readback processes are modeled in software. Since the primary source of noise in TDMR arises from irregularities in the recording medium and leads to highly colored and data-dependent jitter, the pattern dependent noise predictive (PDNP) algorithm is implemented to improve the accuracy and performance of SIR estimation. Furthermore, we study the performance gain of using the PDNP algorithm in SIR estimation through simulations over the Voronoi based media model for different TDMR channel configurations.

No description available.

van der Waals heterostructures meet other low-dimensional materials. Stacking of about 1 nm thick nanosheets with out-of-plane anchor groups functionalized with fullerenes integrates this zero-dimensional material into layered heterostructures with a well-defined chemical composition and without degrading the mechanical properties. The developed modular and highly applicable approach enables the incorporation of other low-dimensional materials, e.g. nanoparticles or nanotubes, into heterostructures significantly extending the possible building blocks.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22452号 / 工博第4713号 / 新制||工||1736(附属図書館) / 京都大学大学院工学研究科材料化学専攻 / (主査)教授 田中 勝久, 教授 三浦 清貴, 教授 藤田 晃司 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

A typical electronic or photonic device may consist of several materials each one potentially meeting at an interface or terminating with a free-surface boundary. As modern device dimensions reach deeper into the nanoscale regime, interfaces and boundaries become increasingly influential to both electrical and thermal energy transport. While a large majority of the device community focuses on the former, we focus here on the latter issue of thermal transport which is of great importance in implementing nanoscale devices as well as developing solutions for on-chip heat removal and waste heat scavenging. In this document we will discuss how modern performance enhancing techniques (strain, nanostructuring, alloying, etc.) affect thermal transport at boundaries and across interfaces through the avenue of three case studies. We use first-principles Density Functional Perturbation Theory to obtain the phonon spectrum of the materials of interest and then use the dispersion data as input to a phonon Boltzmann Transport model. First, we investigate the combined effects of strain and boundary scattering on the in-plane and cross-plane thermal conductivity of thin-film silicon and germanium. Second, we review a recently developed model for cross-dimensional (2D-3D) phonon transport and apply it to 3D-2D-3D stacked interfaces involving graphene and molybdenum disulfide 2D-layers. Third, we combine relevant models from earlier Chapters to study extrinsic effects, such as line edge roughness and substrate effects, on in-plane and through-plane thermal transport in 1H-phase transition metal dichalcogenide (TMD) alloys. Through these investigations we show that: (1) biaxial strain in Si and Ge thin-films can modulate cross-plane conductivity due to strong boundary scattering, (2) the thermal boundary conductance between 2D-3D materials can be enhanced in the presence of an encapsulating layer, and (3) the thermal conductivity of 1H-phase TMDs can be reduced by an order of magnitude through the combination of nanostructuring, alloying, and substrate effects.

京都大学 / 新制・課程博士 / 博士(理学) / 甲第22988号 / 理博第4665号 / 新制||理||1669(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 柳瀬 陽一, 教授 田中 耕一郎, 教授 石田 憲二 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

Gaseous pollution has become a global issue and its presence above certain limits is hazardous to human health and environment. Detection of such gases is an immediate need and researchers around the world are trying to solve this problem. Metal oxides are being used as sensing materials for a long time, but a high operating temperature limits applications in many areas. On the other hand, two-dimensional (2D) materials with high surface-to-volume ratio and chemical stability are promising candidates in the field of gas sensing. This includes monolayer transition metal dichalcogenides, such as MoS2 and WS2, which are direct band gap materials. While few layer transition metal dichalcogenides are indirect band gap materials, they are easier to synthesize than monolayers. Therefore, it is important to understand whether few layer transition metal dichalcogenides possess the same sensing behavior as the corresponding monolayers. For this reason the first part of this dissertation compares the sensing behavior of monolayer and few layer MoS2 and WS2. Two dimensional hexagonal boron nitride is a highly stable structural analogue of graphene. However, its insulating behavior with large band gap is not suitable for sensing. Recently, monolayer Si2BN has been proposed to exist. As the presence of Si makes this material reactive, the second part of this dissertation addresses its application as sensing material. In the _nal part of this dissertation, in search of a metal free, non-toxic, and earth abundant sensor material, further structural analogues of graphene are considered, namely monolayer C3N, monolayer C3Si, and monolayer C6BN. In particular, different theoretical approaches for studying the sensing performance of materials are compared to each other.