Constant stress creep tests were performed in vacuo on alpha titanium in various thermomechanical treatments. At 500°C and 527°C annealed alpha titanium exhibits an anomalous creep arrest in the initial portion of the creep curve. After this creep arrest the creep curves swept up to a true steady state creep rate. This anomalous behavior is attributed to dynamic strain aging. The effect vanishes due to interstitial solute depletion as the interstitials are swept from the lattice by moving dislocations. The prestrained and recovered samples tested at 60006 did not show a creep arrest. This is attributed to even distribution of interstitials on the recovered dislocation substructure making dynamic strain aging less effective. Additionally, transmission electron microscopy indicates that the tilt boundaries of the recovery structure can break down during the initial portion of the creep curve releasing mobile dislocations. In steady state all conditions tested developed a dislocation subgrain substructure. The tendency for dislocation subboundaries to inhabit specific planes is not as marked as it is in the recovered structure. / Master of Science

A key factor in the vertical integration of optical waveguide devices is the uniformity of the surface across which the coupling takes place. This thesis focuses on the fabrication of annealed proton-exchanged (APE) waveguides vertically integrated with chalcogenide waveguides. While titanium diffused waveguides form a surface bump that is approximately twice the size of the originally deposited film, an annealed proton-exchange process produces waveguides with surfaces having 90% less deformation. The theory behind wave guiding devices is explored in this work along with the modeling and simulation of APE waveguides. The results obtained from the simulations are used to aid in the fabrication of these devices. A detailed review of the fabrication process of APE waveguides and chalcogenide waveguides is provided with results obtained from measurements. The first known coupling results for vertically integrated chalcogenide waveguides on top of annealed proton-exchanged waveguides are recorded. This work is concluded with future directions for this research including lowering losses by obtaining better simulation parameters and vertically integrating ring resonators along with ways in which to do this.

This study developed a reinforced steel rod bending machine for rods with diameters of up to 8 mm and annealed wire cutter for up to 5 kg for replacing manual intervention required to bend rods in reinforced concrete columns. This study aims to reduce the physical effort that could lead to occupational diseases, such as tenosynovitis, bursitis, muscle disorders. Clamp manufacturing possesses great risk for workers, who are exposed to injuries while using different cutting devices, such as grinders and electric saws. They also face potential problems such as muscular fatigue due to the nonergonomic and repetitive work positions. The proposed machine features a mechanical dragging and bending systems and manual shears. Additionally, the proposed machine has been designed theoretically and its effectiveness has been assessed through simulations conducted using the SolidWorks CAD software. A bending machine prototype for producing clamps is developed and its machine productivity is measured. Using this machine, approximately 300 clamps can be bent per hour without possessing any risk to the worker.

京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第21196号 / エネ博第370号 / 新制||エネ||72(附属図書館) / 京都大学大学院エネルギー科学研究科エネルギー変換科学専攻 / (主査)教授 木村 晃彦, 教授 星出 敏彦, 教授 今谷 勝次 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DFAM

No description available.

Annealed neural network combines the characteristics of both simulation annealing and Hopfield-Tank neural network, which are high quality solutions and fast convergence. Mobile agent planning is an important technique of information retrieval systems to provide the minimum cost of the location-aware services in mobile computing environment. By taking the time constraints of effective resources into account and the mobile agent to explore the cost optimization, we modify annealing neural network to design a new energy function and control the annealing temperature in order to deal with the dynamic temporal feature of computing environments. We not only consider the server performance and network latency when scheduling mobile agents, but also investigate the location-based constraints, such as the home site of routing sequence of the traveling mobile agent must be the start and end node. To guarantee the convergent stable state and existence of the valid solution, the energy function is reformulated into a Lyapunov function which is combined with the annealing temperature to form an activation function. The connection weights between the neurons and the activation function of state variables in the dynamic network are devised in searching for the valid solutions. Simulation of different coefficients assess the proposed model and algorithm. Furthermore, Taguchi method is used to obtain the optimal combination factors of annealing neural network. The results show that this research presents the feature of both simulated annealing and Hopfield neural network by providing fast convergence and highly quality. In addition with a larger number of sites, the experimental results demonstrate the benefits of the annealed neural network. This innovation would be applicable to improve the effectiveness of solving optimization problems.

Ultrasonic Consolidation of stainless steel structures is being investigated for potential applications. This study investigates the suitability of Stainless Steel 316L annealed (SS316L annealed) as a building material for Ultrasonic Consolidation (UC), including research on Linear Welding Density (LWD) estimation on micrographs of samples. Experiment results are presented that include the effect of UC process parameters on SS316L annealed UC, optimum levels of these parameters, and bond quality of ultrasonically consolidated SS316L annealed structures in terms of LWD. In support to these efforts, a Measurement System Analysis for LWD assessment has been performed, and a new instrument for LWD measurement was developed. This work will determine local maximum LWD UC process parameters for SS316L annealed structures based upon systematic evaluation of sample micrographs.

This thesis explores ideas from transport theory and optimal control to develop novel Monte Carlo methods to perform efficient statistical computation. The first project considers the problem of constructing a transport map between two given probability measures. In the Bayesian formalism, this approach is natural when one introduces a curve of probability measures connecting the prior to posterior by tempering the likelihood function. The main idea is to move samples from the prior using an ordinary differential equation (ODE), constructed by solving the Liouville partial differential equation (PDE) which governs the time evolution of measures along the curve. In this work, we first study the regularity solutions of Liouville equation should satisfy to guarantee validity of this construction. We place an emphasis on understanding these issues as it explains the difficulties associated with solutions that have been previously reported. After ensuring that the flow transport problem is well-defined, we give a constructive solution. However, this result is only formal as the representation is given in terms of integrals which are intractable. For computational tractability, we proposed a novel approximation of the PDE which yields an ODE whose drift depends on the full conditional distributions of the intermediate distributions. Even when the ODE is time-discretized and the full conditional distributions are approximated numerically, the resulting distribution of mapped samples can be evaluated and used as a proposal within Markov chain Monte Carlo and sequential Monte Carlo (SMC) schemes. We then illustrate experimentally that the resulting algorithm can outperform state-of-the-art SMC methods at a fixed computational complexity. The second project aims to exploit ideas from optimal control to design more efficient SMC methods. The key idea is to control the proposal distribution induced by a time-discretized Langevin dynamics so as to minimize the Kullback-Leibler divergence of the extended target distribution from the proposal. The optimal value functions of the resulting optimal control problem can then be approximated using algorithms developed in the approximate dynamic programming (ADP) literature. We introduce a novel iterative scheme to perform ADP, provide a theoretical analysis of the proposed algorithm and demonstrate that the latter can provide significant gains over state-of-the-art methods at a fixed computational complexity.

No description available.

Esta pesquisa engloba o estudo e desenvolvimento de novas heteroestruturas semicondutoras, tomando como base as estruturas SOI (Silicon-On-Insulator - silício sobre isolante) obtidas pela técnica Smart Cut, estudadas nestes últimos anos no Departamento de Engenharia de Sistemas Eletrônicos da Escola Politécnica da Universidade de São Paulo (EPUSP). Esta técnica combina a solda direta para a união de lâminas e a implantação iônica (I/I) de íons leves para a separação de camadas especificadas. São essenciais na preparação destas estruturas SOI, processos de I/I, limpeza e ativação das superfícies das lâminas e recozimentos em fornos a temperaturas moderadas. Estudamos também, diferentes métodos para a obtenção de novas heteroestruturas, basicamente combinando as técnicas de fabricação da estrutura SOI e os métodos de formação do carbeto de silício (SiC), que chamaremos de heteroestruturas SiCOI (Silicon Carbide-On-Insulator). O método usado para a formação do SiC depende, em cada caso, das características desejadas para o filme que, ao mesmo tempo, estão relacionadas com a aplicação à qual estará destinado. Analisamos três métodos de obtenção do material SiC com características específicas diferentes. A metodologia proposta aborda as seguintes tarefas: Tarefa 1: Obtenção de estruturas SOI pelo método convencional utilizado em trabalhos anteriores e melhoramento das características superficiais da estrutura resultante. Tarefa 2: partindo de uma lâmina de Si previamente coberta por uma camada isolante, fabricar a heteroestrutura SiC/isolante/Si, onde a camada de SiC é crescida pelo método de deposição química de vapor assistida por plasma (PECVD). O filme obtido por deposição PECVD é amorfo e portanto são necessárias etapas de cristalização posteriores ao crescimento. Tarefa 3: partindo de uma estrutura SOI, fabricar a heteroestrutura SiC/SiO2/Si, onde a camada de SiC é obtida por implantação de íons de carbono (C+) na camada ativa de Si da estrutura SOI para sua transformação em SiC. Tarefa 4: partindo de uma estrutura SOI, fabricar a heteroestrutura SiC/SiO2/Si, onde a camada de SiC é obtida por conversão direta da camada ativa de Si da estrutura SOI em SiC como resultado da carbonização do Si usando exposição a ambiente de hidrocarbonetos. Como resultado deste trabalho foram obtidas estruturas SOI Smart Cut com valor médio de rugosidade superficial dentro dos valores esperados segundo a bibliografia consultada. Durante o desenvolvimento de heteroestruturas SiC/isolante/Si obtidas utilizando a técnica de PECVD obtivemos filmes com boas características estruturais. Os recozimentos feitos em ambiente de N2 aparentemente trazem resultados satisfatórios, conduzindo à completa cristalização dos filmes. Nas análises feitas para a fabricação de heteroestruturas SiC/isolante/Si utilizando I/I de carbono confirma-se a formação de c-SiC depois de realizado o recozimento térmico. / In this work we study new semiconductors heterostructures, based on SOI (Silicon-On- Insulator) structures obtained by \"Smart-Cut\" process, that were studied in the last years at Departamento de Engenharia de Sistemas Eletrônicos da Escola Politécnica da Universidade de São Paulo (EPUSP). This technique combines high-dose hydrogen ion implantation (I/I) and direct wafer bonding. To produce SOI structures some processes are essential: I/I process, cleaning and activation of the surfaces, and conventional thermal treatments at moderated temperatures. We also investigate different methods to obtain new heterostructures, basically combining SOI technologies and silicon carbide (SiC) growth processes, which will be called as SiCOI (Silicon Carbide-On-Insulator) heterostructures. The utilized methods to obtain the SiC are related, in each case, with the desired film\'s characteristics, which at the same time are associated with the final application. We analyze three methods to obtain SiC material with specific different characteristics. The proposed methodology approaches the following tasks: Task 1: Fabrication of SOI structures by the conventional technology previously used by us, and the improvement of superficial characteristic of the final structure. Task 2: Fabrication of SiC/insulator/Si heterostructures from Si substrate previously covered with an insulator capping layer, where the SiC layer is deposited by plasma enhanced chemical vapor deposition (PECVD). The PECVD film is amorphous and therefore, a thermal annealing step is necessary for crystallization. Task 3: Fabrication of SiC/SiO2/Si heterostructures from SOI structure, where the SiC layer is synthesized through a high dose carbon implantation into the thin silicon overlayer of a SOI wafer. Task 4: Fabrication of SiC/SiO2/Si heterostructures from SOI structure, where the SiC layer is achieved by direct carbonization conversion of the silicon overlayer of a SOI wafer In this work we have obtained Smart Cut SOI structures with surface roughness similar to the previous reported. We also obtained SiC/insulator/Si heterostructures with good structural characteristics using PECVD technique. The investigated N2 thermal annealing appears to be suitable for the crystallization of all the amorphous films deposited by PECVD. We have shown the possibility of using carbon ion implantation and subsequent thermal annealing to form c-SiC for SiC/insulator/Si heterostructures.