京都大学 / 新制・課程博士 / 博士(工学) / 甲第24616号 / 工博第5122号 / 新制||工||1979(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 田中 功, 教授 奥田 浩司, 教授 中村 裕之 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

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Bolivia är ett land i Sydamerika där en stor del av befolkningen lever utan tillgång till tillförlitligelektricitet på grund av olika topografiska och/eller ekonomiska förhållanden. Lösningen pådetta problem har varit att förlänga det nationella elnätet vilket är tidskrävande och inte alltidekonomiskt försvarbart. Därför har mindre system, för ett samhälle eller en familj, börjatutvecklas. Dessa system består vanligtvis av en dieselgenerator men i vissa fall är det även ettdiesel-/PV-hybridsystem. Syftet med denna rapport är att analysera potentialen hos olikahybridsystem samt att sammanställa tidigare arbeten om energi- och hybridsystem i Bolivia somen grund för framtida studier.Hypotesen i denna rapport är att Bolivia kan delas in i tre olika geografiska områden (3 fall) ochatt ett hybridsystem kan utformas för var och ett av dessa områden där sammasystemkonfiguration kan användas, endast i olika skalor. Genom detta kan kostnaden minskasför samhället eftersom det kan standardiseras. Möjligheten för samhällen, geografiskt näravarandra, att dela ett system och anslutas via ett minigrid kommer också analyseras.För detta kommer potentialen och efterfrågan på energi runt om i landet att undersökas och olikateknologier för förnybara energisystem kommer också att övervägas. Från denna informationkommer flera optimeringar i HOMER PRO-mjukvaran att utföras för att designa systemetskonfiguration och analysera systemets effektivitet.I rapporten uppskattas behovet för två olika scenarion. Ett samhälle med endast bostäder(1.5 kWh/hushåll/dag) och ett med fungerande infrastruktur så som skolor, gatubelysning etc.(4 kWh/hushåll/dag). Dessa undersöks sedan i två olika skalor vardera för att se hur ett systembeter sig när samhället växer. Behovet för ett samhälle med endast bostäder kommer analyserasför 10 och 20 hushåll medans samhället med infrastruktur analyseras för 50 och 100 hushåll.Studiens slutsats är att PV-/dieselsystemet är det mest ekonomiskt hållbara, förutom då en starkhydroresurs finns tillgänglig, för då kan ett PV-/hydrosystem eller endast hydrosystem fyllabehovet till ett bättre pris. Dessa system är även mer ekologiskt hållbara. Det kunde även ses attsmå förändringar med mer förnyelsebara resurser, för storskaliga system, kunde minskadieselförbrukningen väsentligt och detta med en låg prisökning. Förlängningen av etthybridsystem till flera samhällen visade sig emellertid inte vara effektivt. / Bolivia is a country in South America where a large part of its population lives without access toreliable electricity due to various topographical or/and economic conditions. The solution to thisproblem has been to extend the national electricity grid. This takes time and is not economicallysustainable in all cases. Smaller systems, for a community or household, have therefore started tobe developed. These systems usually consist out of a diesel generator or, in some cases, adiesel/PV hybrid system. The purpose of this report is to analyse the potential of different hybridsystems for different areas in Bolivia and to compile the previous work undertaken in energydemand and hybrid systems in Bolivia. From the gathered information, future studies will besuggested.The hypothesis of this report is that Bolivia can be divided into three different geographical areas(3 cases) and a hybrid system can be designed for each one of these areas. The same systemconfiguration can be used in all cases, only used in different scales. The cost can then be reducedfor the community, since it can be standardized. The report will also look at the possibility forcommunities’, close to each other, to share one system and be connected through a minigridsystem.To analyse this, the potential/demand of energy around the country will be examined anddifferent technologies of renewable energy systems will be considered. From this information,multiple optimizations in the HOMER PRO software will be performed to design and analysethe effectiveness of the systems. Estimations for two different scenarios will be made. Onecommunity with only resident houses (1.5 kWh/household/day) and one society with workinginfrastructure such as schools and public lighting (4 kWh/household/day). These are thenexamined in two different scales each, to see how a system behaves when scaled up. The demandfor a community with only private houses will be analyzed for 10 and 20 households. The largersociety with infrastructure for 50 and 100 households.The conclusion that could be drawn after the project is that the PV / Diesel system is the mosteconomically sustainable in all cases, except if a strong hydro-recourse is available then aPV/hydro or single hydro system can fill the demand for a better price. These systems are alsomore ecologically sustainable. It was also observed that minor changes, more renewableresources, in the system configuration for large-scale systems could significantly reduce dieselconsumption and at a lower price. The extension of a hybrid system to several communities didnot prove to be effective.

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This thesis discusses Kaplan, a free conformer searching package, available at github.com/PeaWagon/Kaplan / Conformer searching algorithms find minima in the Potential Energy Surface (PES) of a molecule, usually by following a torsion-driven approach. The minima represent conformers, which are interchangeable via free rotation around bonds. Conformers can be used as input to computational analyses, such as drug design, that can convey molecular reactivity, structure, and function. With an increasing number of rotatable bonds, finding optima in the PES becomes more complicated, as the dimensionality explodes. Kaplan is a new, free and open-source software package written by the author that uses a ring-based Evolutionary Algorithm (EA) to find conformers. The ring, which contains population members (or pmems), is designed to allow initial PES exploration, followed by exploitation of individual energy wells, such that the most energetically-favourable structures are returned. The strengths and weaknesses of existing publicly available conformer searchers are discussed, including Balloon, RDKit, Openbabel, Confab, Frog2, and Kaplan. Since RDKit is usually considered to be the best free package for conformer searching, its conformers for the amino acids were optimised using the MMFF94 forcefield and compared to the conformers generated by Kaplan. Amino acid conformers are well characterised, and provide insight for protein substructure. Of the 20 molecules, Kaplan found a lower energy minima for 12 of the structures and tied for 5 of them. Kaplan allows the user to specify which dihedrals (by atom indices) to optimise and angles to use, a feature that is not offered by other programs. The results from Kaplan were compared to a known dataset of amino acid conformers. Kaplan identified all 57 conformers of methionine to within 1.2Å, and found identical conformers for the 5 lowest-energy structures (i.e. within 0.083Å), following forcefield optimisation. / Thesis / Master of Science (MSc) / A conformer search affords the low-energy arrangements of atoms that can be obtained via rotation around bonds. Conformers provide insight about the chemical reactivity and physical properties of a molecule. With increasing molecule size, the number of possible conformers increases exponentially. To search the space of possible conformers, this thesis presents Kaplan, which is a software package that implements a novel directed, stochastic, sampling technique based on an Evolutionary Algorithm (EA). Kaplan uses a special type of EA that stores sets of conformers in a ring-based structure. Unlike other conformer-specific packages, Kaplan provides the means to analyse and interact with found conformers. Known conformers of amino acids are used to verify Kaplan. Other tools for generating conformers are discussed, including a comparison of freely available software. Kaplan effectively finds the conformers of small molecules, but requires additional parametrisation to find the conformers of mid-sized molecules, such as Penta-Alanine.

The reparametization of semiempirical Hamiltonians is an emerging method used in direct dynamics studies. The use of semiempirical Hamiltonians in direct dynamics studies diminishes the computational cost of trajectory calculations and negates the need for an analytical potential energy surface when performing reaction dynamics studies. The reparametization of semiempirical Hamiltonians increases the agreement with experiment and high level ab initio theory. We have chosen to create one set of new parameters that apply to two related reactions, F + CH₄ → HF + CH₃ and F + C₂H₆ → HF + C₂H₅. We have performed an electronic structure study for these reactions. The ab initio data obtained from the electronic structure study is then used as the reference for a reparametization of the PM3 Hamiltonian. The reparametization has improved the ab initio and PM3 reaction energy and potential energy surface scan agreement. This new set of parameters for PM3 (SRP-PM3) is used to perform a direct quasiclassical trajectory study of the reactions. The vibrational and rotational HF distributions calculated using SRP-PM3 are compared with experiments. We have observed an improvement in the agreement with experimental vibrational distributions but have seen no change in the rotational distributions. / Master of Science

Yes / A new type of model, FFLUX, to describe the interaction between atoms has been developed as an alternative to traditional force fields. FFLUX models are constructed from applying the kriging machine learning method to the topological energy partitioning method, Interacting Quantum Atoms (IQA). The effect of varying parameters in the construction of the FFLUX models is analyzed, with the most dominant effects found to be the structure of the molecule and the number of conformations used to build the model. Using these models the optimization of a variety of small organic molecules is performed, with sub kJ mol-1 accuracy in the energy of the optimized molecules. The FFLUX models are also evaluated in terms of their performance in describing the potential energy surfaces (PESs) associated with specific degrees of freedoms within molecules. While the accurate description of PESs presents greater challenges than individual minima, FFLUX models are able to achieve errors of <2.5 kJ mol-1 across the full C-C-C-C dihedral PES of n-butane, indicating the future possibilities of the technique.

No / Nonadiabatic Monte Carlo transition-state theory is used to explore competing C¿Cl and C¿Br bond fission processes in a simple model of 1[n,pi*(CO)] photoexcited bromoacetyl chloride. Morse potentials are used to represent bond stretching coordinates, and the positions and magnitudes of nonadiabatic coupling between excited state potentials are modeled using ab initio data. The main effect of nonadiabaticity is to favor C¿Cl fission over C¿Br, despite a larger barrier to C¿Cl dissociation. The absolute values of the rate constants are smaller than observed experimentally, but the calculated branching ratios are close to the experimental value. For C¿Cl fission, it is shown that the minimum energy crossing point is not sufficient to describe the rate constant, suggesting that care must be taken when using alternative models which make this assumption.

Understanding pattern formation in nature is an important topic in applied mathematics. For more than three decades, the Ohta–Kawasaki energy has attracted considerable attention from applied mathematicians. This energy functional, which combines surface energy and electrostatic potential energy, captures the intricate patterns observed in various physical and biological systems. Despite its apparent simplicity, the Ohta–Kawasaki energy serves as a versatile framework for describing a wide range of pattern formation phenomena induced by competing interactions. In this dissertation, we aim to gain a better understanding of the important properties of the Ohta–Kawasaki energy, specifically its stationary points, global minimizers, and energy landscape. We explore these properties in the context of broad applications such as nuclear physics, block copolymers, and biological membranes. In order to investigate the complicated geometries in these applications, we utilize asymptotic analysis and numerical simulations. Firstly, we explore the stationary points of the Ohta–Kawasaki energy. Specifically, we study how a three-dimensional ball loses stability as the nonlocal coefficient increases in the binary case. Our approach combines numerical simulations and bifurcation analysis. We calculate the minimum energy path for the transition from a single ball to two separate balls, as well as the bifurcation branch orginating from the ball. In the context of nuclear physics, this bifurcation branch is known as the Bohr–Wheeler branch. Our simulations suggest that, unlike the previous understanding, all the stationary points on this bifurcation branch are unstable. Similar results are observed in two dimensions. This finding illustrates the unexpected mechanism governing the stability loss of balls and disks. Secondly, we explore the global minimizers of the Ohta–Kawasaki energy. We numerically compute the one-dimensional energy minimizers of relatively short patterns in the non-degenerate ternary case. Inspired by our numerical results, we propose an array of periodic candidates. We then show that our candidates can have lower energy than the previously conjectured global minimizer which is of the cyclic pattern. Our results are consistent with simulations based on other theories and physical experiments of triblock copolymers, in which noncyclic lamellar patterns have been found. This finding indicates that even in one dimension, the global minimizers of the Ohta–Kawasaki energy can exhibit unexpected richness. Lastly, we explore the energy landscape of the Ohta–Kawasaki energy. We propose a phase-field reformulation which is shown to Gamma-converge to the original sharp interface model in the degenerate ternary case. Our phase-field simulations and asymptotic results suggest that the limit of the recovery sequence exhibits behaviors similar to the self-assembly of amphiphiles, including the formation of lipid bilayer membranes. This finding reveals the intricate landscape of the Ohta–Kawasaki energy. In summary, this dissertation sheds light on three important aspects of the Ohta–Kawasaki energy: its stationary points, global minimizers, and energy landscape. Our findings are timely contributions to the ongoing research on pattern formation driven by energetic competition.

Lors d’une rentrée atmosphérique, les boucliers thermiques des véhicules spatiaux subissent un échauffement considérable dont une fraction significative (~30%) est attribuée aux réactions chimiques à leur surface. Cette thèse contribue à la compréhension de cette réactivité hétérogène, la catalycité, au moyen des outils de la chimie théorique. Une méthode de construction de surface d’énergie potentielle globale est développée et appliquée à l’étude de la dynamique de processus élémentaires (adsorption moléculaire dissociative, absorption atomique, recombinaison Eley-Rideal …) pour les systèmes chimiques N,N2/W(100,110) et O,O2/Cu(100). Ces approches sont ensuite couplées à un modèle cinétique permettant de quantifier la catalycité. / During an atmospheric re-entry, the thermal shields of spacecrafts undergo an important heating, a significant fraction (~30%) of which is due to the chemical reactions at their surface. This thesis is a contribution to the understanding of this heterogeneous reactivity, catalycity, with the tools of theoretical chemistry. A method to build a global potential energy surface is developed and applied to the study of elementary processes dynamics (dissociative molecular adsorption, atomic absorption, Eley-Rideal recombination …) for the N,N2/W(100,110) and O,O2/Cu(100) chemical systems. These approaches are then coupled with a kinetic model quantifying catalycity.