京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22776号 / 工博第4775号 / 新制||工||1747(附属図書館) / 京都大学大学院工学研究科材料工学専攻 / (主査)教授 杉村 博之, 教授 邑瀬 邦明, 教授 宇田 哲也 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Concentrated solar power is a growing but expensive alternative energy resource. One of the most common issues faced when it comes to solar dish design is the complex trade-off between cost and optical quality. A novel solar dish reflector setup that makes use of low-cost, commercial television satellite dishes to support aluminised plastic membranes in a multifaceted vacuum-membrane concentrator was investigated in this work. The design aims to reduce costs while maintaining high optical accuracy with the added benefit of optical adjustability. The flux distribution of the novel solar dish reflector setup had to be determined to make recommendations on the feasibility of the design. This research presents a method to determine the expected solar flux distribution from lunar tests using a Canon EOS 700D camera. Experimental tests and different pollution treatment methods were conducted using lunar flux mapping techniques. A numerical model of the experimental setup, based on photogrammetry results of the membrane surface, was also developed in SolTrace to ascertain the sources of error and allow for further design improvements. Preliminary testing proved that JPEG image formats yielded insufficient accuracy in capturing the incident flux when compared to RAW images. Based on the flux ratio maps, the intercept factor for a large multifaceted dish setup was calculated as 88.6% for an aperture size of 0.25 m × 0.25 m, with a maximum solar flux of 1 395 kW/m2 for a 1 000 W/m2 test case. / Dissertation (MSc (Mechanical Engineering))--University of Pretoria, 2020. / National Research Foundation (NRF) / Mechanical and Aeronautical Engineering / MSc (Mechanical Engineering) / Unrestricted

The space environment possesses numerous unique and unusual attributes, creating challenges that must be considered in order to accomplish a successful space mission. Two of the detrimental aspects of the space environment include Atomic Oxygen, AO, and Ultraviolet, UV, radiation. UV radiation becomes more severe in space as there is no atmosphere to attenuate incoming photons, thereby exposing spacecraft to radiation that never reaches the surface of the Earth. Overall, space vehicles are exposed to a total of 107.4 Watts/m2 of light shorter than 400 nm. AO is created by the photo disassociation of molecular oxygen by UV radiation with wavelengths less than ~242.1 nm. AO is a major portion of the neutral atmosphere, and is the dominant species for altitudes between 180 and 675 km. Each of these environments can cause significant damage to spacecraft materials as they have sufficient energy to break molecular bonds: a generalization of AO energy is 4.5 +/- 1 eV while Vacuum Ultraviolet, VUV, radiation can break bonds as strong as 12.4 eV. Synergistic affects are observed when these two environments interact with materials simultaneously, resulting in an accelerated erosion rate. An apparatus has been developed in California Polytechnic State University’s, Cal Poly’s, space environments laboratory that can simulate the AO and VUV environments individually and simultaneously. This apparatus utilizes a radio frequency, RF, generator to produce a capacitively coupled plasma to create AO in conjunction with a deuterium lamp capable of emitting UV radiation as short as 115 nm. The system has been shown to produce an AO flux of 1.70 +/- 0.07•1016 atoms/cm2 while providing an equivalent sun power 4.5 times greater the solar output in the 120-200 nm region of UV light; all of this has been performed at a base pressure near 175 mTorr. Long duration tests of 24 hours, which would be analogous to durations used in a material interaction study, have shown an effective fluence of 1.47 +/- 0.06•1021 atoms/cm2, which would equate to an orbital exposure on the order of weeks to months. For the same duration a sample can be exposed to 108 equivalent sun hours of 120-200 nm radiation. Results from the simultaneous exposure also manifested an accelerated erosion rate, the expected synergetic reactions between the two environments.

This thesis deals with preparation of organic molecular thin film compounds and its properties like morphology and purity. The vapour deposition was used for thin films preparation, because used materials are very few soluble. Thin films properties were characterized with the infrared spectroscopy (FTIR) and scanning electron microscope. There are described basics of infrared spectroscopy, spectra measurement and interpretation in the theoretical part. Process of thin film preparation is also described in this part. In the experimental part are described used vacuum technology and measuring instruments, process of sample measurement and there is the list of studied materials. 12 derivates of diketopyrrolopyrrols (DPP) were studied in this thesis. Diketopyrrolopyrroles (DPP) and its derivates have interesting chemical and physical properties, expecting wide range of applications, especially in electronics industry.

Goal of this work is to judge the effect of different amount of waste aggregate in particular material mixture for production of clay roof tile according to norm ČSN EN 1304 (TONDACH Česká republika s r.o. – cihelna Šlapanice). This document is putting together published experience with usage of waste aggregate in the brickworks business. The effect of different mixture amount was tested in laboratories. Tests were most importantly aimed at temperature stress during burn, vacuum absorption method and mass by volume.

This diploma thesis describes the design of a translation stage for focusing objective inside the LIBS interaction chamber. It contains a description of the fundamentals and basic functions of LIBS spectroscopy. Moreover, in the thesis an overview of different translation stages as possible LIBS components is given. Their advantages and disadvantages for use in a vacuum translation stage construction are evaluated. The thesis describes the final solution of a linear translation stage for focusing objective, and his advantages for LIBS method

The aim of this thesis is constructional concept of diaphragm press for thermoplastic forming. The press consists of two chambers. First chamber is designed for forming of semi-finished product to forming temperature and second chamber is designed for heating the semi-finished product. Theoretical part of this thesis is focused on technologies in use and shaping of plastic description. Practical part of this thesis deals with detailed description of press concept including consistence calculations and drive units calculations. The whole concept, including its individual parts, is designed using the Autodesk Inventor software. At the end of this thesis, there is the economic and safety analysis.

The aim of thesis is to describe the basic methods called Rapid Prototyping in theory and using one of them to create master model. Master model will be used to create silicone mould where a limited series of wax models will be by means of vacuum casting chamber. They will also be used to make ceramic form in which the final pad will be cast from freely accessible materials. After processing it the suitability of the proposed technologies for the production of the part in question will be assessed.

In this master's thesis a design of door for helium quenching furnace is described. Based on background research, several options for the design have been compared. All calculations were carried out based on structural needs resulting from high pressure gas quenching technology. By the ending of this thesis a mounting procedure and rough cost price estimation is described. Part of master's thesis is also a virtual 3D prototype and a drawing documentation.

This diploma thesis deals with measuring the tightness of the hermetic area of nuclear power plant in the way of improving safety. Describes the layout and function of this area - the primary circuit of NPP with WWER 440/213 reactors, as well as methodology for leakage search and leakage calculation procedures. Personal contribution to the issue is a proposal improving tightness of the current state in hermetic area of NPP Jaslovské Bohunice – transition of jacketed pipe designed to collect water from the floor in the box of the steam generator to the heat exchanger of the shower system. This system belongs to the safety system designed to reduce pressure in the LOCA type of accident.