This thesis describes possible applications of Prony's method in timing analysis of digital circuits. Such applications include predicting the future shape of the waveform in DTA(Dynamic Timing Analysis) and delay look-up table in STA(Static Timing Analysis). Given some equally spaced output values, the traditional Prony's method can be used to extract poles and residues of a linear system, i.e. to characterize a waveform using an exponential function. In this thesis, not only values but also equally spaced derivatives are tested. Still using same idea of the traditional Prony's method, poles and residues can also be extracted with those values and derivatives. The resultant poles and residues will be used to predict the output waveform in DTA analysis. The benefits brought by the using of derivatives include less simulation steps and less CPU time consuming than the regular constant step simulation. As a matter of fact, the Prony's method can precisely approximate a complicated waveform. Such property can be applied for STA analysis. The Prony's approximation can be used to precisely record an output waveform, which is used as an entry of the look-up table of STA. Since the accuracy of STA analysis relies on the accuracy of the input and output waveform in the look-up table, the accuracy of the Prony's approach is promising.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21096号 / 工博第4460号 / 新制||工||1693(附属図書館) / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 高岡 昌輝, 教授 田中 宏明, 准教授 大下 和徹 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Results of this research are available online in two published papers. / The main focus of this research was to synthesize and then to characterize the potential high-performance thermoelectric materials. In this regard, we have prepared a series of pure RECuSe2 (with RE = Pr, Sm, Gd, Dy and Er) and RECuTe2 (with RE = Er, Dy and Gd) and analyzed their crystal structure, electronic and physical properties. We used powder and single crystal X-ray diffraction techniques to analyze their crystal structures and employed energy dispersive X-ray spectrometry (EDS) to verify their chemical compositions. The temperature stability of the synthesized samples was examined by differential thermal and gravimetrical analysis. The high-purity consolidated pellets were prepared for physical properties measurements. We analyzed the relationship between their crystal structures and pertinent electronic properties through the LMTO calculations. The RECuSe2 phases adopt two structures, monoclinic and trigonal. The monoclinic structure (P21/c, z = 4) is observed for lighter rare earths (RE = Pr, Sm and Gd) and Cu-disordered trigonal structure for heavier rare earths (P m1, z = 1, RE = Dy and Er). The resistivity and Seebeck coefficient measurements indicate that the studied selenides are p-type semiconductors with relatively small activation energies (0.045-0.12 eV). However, their electrical resistivities are too high (0.49-220 Ohmcm at room temperature) to make them competitive thermoelectric materials. Electronic structure calculations indicate presence of a band gap in the RECuSe2 phases. The synthesized RECuTe2 phases (RE = Er, Dy and Gd) adopt a monoclinic-distorted variant (C2/m, z = 2) of the trigonal structure (P m1, Z= 1) observed for the RECuSe2 (with RE = Dy, Er). While such disorder may be beneficial for lowering their thermal conductivity, large values of electrical resistivity (0.02-0.87 Ohmcm at room temperature) make these phases unsuitable for practical applications. Comparing to the corresponding semiconducting selenides, the tellurides have lower resistivities, and display a metallic type resistivity. Such behavior stems from the closure of band gaps, which is verified by the electronic structures calculations. Structurally the RECuTe2 phases (with RE = Er, Dy and Gd) are similar to RECuSe2 with the P m1 structure. The monoclinic distortion in RECuTe2 is driven by Cu displacement inside the larger tetrahedral voids in the hexagonal close packing of the Te atoms. Most likely, Cu shifts to one side of the Te tetrahedra to optimize the Cu-Te interactions. / Thesis / Candidate in Philosophy

No description available.

No / To analyze the fatty acid contents of Buddleja asiatica Lour, both the non-volatile oil and fat obtained from the n-hexane soluble sub-fraction were subjected to GC/MS using BSTFA (N,O-bis(trimethylsilyl) trifloroacetamide) derivatization. The oil showed the presence of six fatty acids including palmitic acid (46.75 %), linoleic acid (37.80 %), stearic acid (10.98 %), arachidic acid, margaric acid and lignoceric acid (< 3 %). Analysis of the fat revealed nine fatty acids including lignoceric acid (43.12 %), behenic acid (26.39 %), arachidic acid (9.29 %) and stearic acid (5.3 %). Cerotic acid, montanic acid, melissic acid and palmitic acid were found in low amounts (< 5 %) while trycosylic acid (4.83 %) was the only fatty acid with odd number of carbon atoms. The oil showed a low thermal stability. / Higher Education Commission Pakistan

Submitted by Angela Maria de Oliveira (amolivei@uepg.br) on 2018-11-06T17:35:07Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Geisa Liandra.pdf: 3414564 bytes, checksum: b9fc4d1a56d56c9c5c38f3f88871810e (MD5) / Made available in DSpace on 2018-11-06T17:35:07Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Geisa Liandra.pdf: 3414564 bytes, checksum: b9fc4d1a56d56c9c5c38f3f88871810e (MD5) Previous issue date: 2017-02-09 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Araucaria angustifolia (Bert.) O. Kuntze é uma conífera presente nas florestas brasileiras e as suas sementes apresentam alto teor de amido. Os pinhões utilizados nesta pesquisa foram provenientes de materiais genéticos e selecionados com base em testes preliminares por apresentarem temperatura de gelatinização inferior a 60ºC. Esta é considerada uma característica interessante e vantajosa, podendo economizar tempo e energia durante o processo de gelatinização do amido. O amido na sua forma natural apresenta limitações, portanto uma das alternativas é a hidrólise ácida que tem o intuito de alterar as suas propriedades físico-químicas. Este tratamento aliado a solução alcoólica apresenta a capacidade de recuperar grande parte do grânulo. O objetivo deste estudo foi identificar os efeitos da modificação ácida em meio aquoso e alcoólico de amidos de pinhão (A. angustifolia) com temperaturas de gelatinização abaixo de 60 ºC. As amostras foram avaliadas quanto ao pH e Colorimetria, por análise térmica (TG-DTA e DSC), pelo comportamento reológico (RVA), por análises estruturais (DRX e MEV) e por análises estatísticas (ANOVA e Tukey). A recuperação do grânulo de amido foi maior no meio aquoso e no meio alcoólico os valores ficaram próximos a 90% de recuperação. Os valores de pH comprovaram que o processo eliminou o ácido utilizado na modificação e a colorimetria identificou a coloração branca e levemente amarela para ambos os acessos, mostrando que os tratamentos não alteraram as características colorimétricas dos amidos de pinhão. Nas curvas TGDTA em ar sintético foram observadas três perdas de massa. As amostras nativas apresentaram diferença no DTA e as temperaturas finais demonstraram maior resistência térmica dos amidos. Nas curvas TG-DTA em nitrogênio foram encontradas duas perdas de massa. As amostras tratadas apresentaram semelhança no DTA e as temperaturas finais não foram alteradas devido à atmosfera inerte. Na análise de DSC, a Tc e a ∆Hgel não apresentaram diferenças significativas, apenas no To e Tp. Os tratamentos mais intensos mostraram leve resistência térmica e menor ∆Hgel. No RVA foi observado redução nos parâmetros de viscosidade conforme a intensidade do tratamento. O DRX identificou o padrão do tipo C para os amidos e a cristalinidade relativa aumentou conforme a intensidade da hidrólise ácida. Pelo MEV foram observadas alterações superficiais nos grânulos. Diante dos resultados encontrados, os amidos de pinhão demonstraram ser promissores para aplicações industriais visando specialties, ou seja, para produtos com escala reduzida. O intuito é estimular os pequenos produtores, proporcionar agregação de valor ao produto final e a manutenção da espécie A. angustifolia. / Araucaria angustifolia (Bert.) O. Kuntze is a conifer present in Brazilian forests and its seeds are high in starch. The pinhões used in this research were derived from genetic material and selected based on preliminary tests because they presented a gelatinization temperature below the 60 ºC. This is considered an interesting and advantageous feature, which can save time and energy during the starch gelatinization process. Starch in its natural form has limitations, so one of the alternatives is acid hydrolysis, which has the purpose of altering its physicochemical properties. This treatment combined with alcoholic solution has the ability to recover majority of the granule. The aim of this study was to identify the effects of acidic modification on aqueous and alcoholic solutions of pinhão starches (A. angustifolia) with gelatinization temperatures below of 60 ºC. The samples were evaluated for pH and Colorimetry by thermal analysis (TG-DTA e DSC), by rheological behavior (RVA), by structural analysis (XRD and SEM) and by statistical analysis (ANOVA and Tukey). The recovery of the starch granule was higher in the aqueous medium and in the alcoholic solution; the values were close to 90% recovery. The pH values showed that the process eliminated the acid used in the modification and the Colorimetry identified the white and slightly yellow coloration for both accessions, showing that the treatments did not alter the colorimetric characteristics of the pinhão starches. In the TG-DTA curves in synthetic air, three mass losses were observed. The native samples presented a difference in the DTA and the final temperatures showed a higher thermal resistance of the starches. In the TG-DTA curves in nitrogen, two mass losses were found. The treated samples showed similarity in DTA and the final temperatures were not changed due to the inert atmosphere. In the DSC analysis, Tc and ΔHgel did not show significant differences, only in To and Tp. The most intense treatments showed light thermal resistance and lower ΔHgel. In the RVA, a reduction in the viscosity parameters was observed according to the intensity of the treatment. XRD identified the type C pattern for starches and relative crystallinity increased as the acid hydrolysis rate increased. Superficial changes in the granules were observed by SEM. Considering the results found, the pinhão starches demonstrated to be promising for industrial applications aiming specialties, that is, for products with reduced scale. The intention is to stimulate small producers, provide benefits to the final product and the maintenance of the species A. angustifolia.

In the present dissertation the formation of microstructure, the kinetics of densification and the formation of surface layers developing during liquid phase sintering of silicon carbide are studied. The focus is on the additive systems Al2O3 plus Y2O3 and AlN plus Y2O3. Phase and especially liquid phase formation in both of the systems SiC, Al2O3 , Y2O3 and AlN, Al2O3 , Y2O3 are investigated in detail examining 12 espectively 17 different compositions per system. Melting temperatures have been determined by TG/DTA, in both systems for the first time. Phase composition of samples was analysed by the combination of XRD, SEM and EDX. In the system SiC, Al2O3 , Y2O3 the formation of the phases expected from the quasibinary Al2O3 , Y2O3 could be observed thus silicon carbide has to be in equilibrium with the oxide additives. The low solubility of SiC in the oxide melt, which was suggested by Hoffmann and Nader, could be confirmed. In the system AlN, Al2O3 , Y2O3 the formation of phases as stated by Medraj was confirmed, except for the dimension of the stability region of the γ- spinel and YAG which is wider in the present work. For the first time diffusion coefficients of the species Y3+ and Al3+ in the oxide melt formed by Al2O3 and Y2O3 at temperatures above 1825 ◦ C were determined. The values are in the order of 2 · 10−6 cm2 /s which results in a diffusion length of 14.1 μm for a diffusion time of one second. This allows the fast equilibration of Y and Al deficiencies. Kinetics of densification was modeled by kinetic field, master curve and thermokinetic method, based on detailed experimental investigation of the shrinkage during liquid phase sintering of SiC. It could be proved that the first 30 − 40 % of densification are controlled by solid phase reactions which accelerate particle rearrangement without presence of a liquid phase. During the remaining 60 − 70 % of densification a liquid is present, resulting in the predominance of mechanisms of liquid phase sintering. The models deliver activation energies in the range from 608 KJ/mol to 1668 kJ/mol and allow, within the scope of validity of each method the prediction of densification during liquid phase sintering of silicon carbide. When sintering silicon carbide with Al2O3 plus Y2O3 the formation of several surface layers, depending on atmosphere, maximum temperature, dwelling time and amount and composition of additives was observed. In nitrogen atmosphere with low partial pressures a surface layer consisting of AlN is forming whilst at high partial pressures SiAlON- polytypes occur. After sintering in Argon or Ar-CO- atmosphere three main types of surface layers are present. One consists of alumina, one contains only YAG and one shows highly porous, additive depleted regions. An explanation for the formation of the several surface layers could be given by the combination of the determined diffusion coefficients with the results achieved in the thermodynamics part. The results achieved in this work can be a contribution to the knowledge based design of the production process of liquid phase sintering of silicon carbide.

En vue de la réduction des problèmes engendrés par les phénomènes de retrait-gonflement des sols dans la dépression de la Lama au Sud du Bénin, nous avons entrepris des recherches dans le but de maîtriser le comportement de ces sols. Six échantillons de sols fins dont quatre argileux de cette région ont été prélevés. Différents essais ont été réalisés : une caractérisation macroscopique concernant les propriétés mécaniques et géotechniques et les essais microscopiques prenant en compte les analyses chimiques, thermiques, minéralogiques et microstructurales. Les sols étudiés sont constitués de différents minéraux argileux. Celle à structure fibreuse est à l'origine d’un comportement macroscopique particulier décelé par l’essai de gonflement libre. Les essais ont confirmé le fort potentiel de gonflement et de retrait de certains sols qui sont donc à l'origine des fortes dégradations rencontrées.Les résultats montrent que les sols traités se distinguent par les performances mécaniques acquises et peuvent être utilisés à différents niveaux de la chaussée selon leur teneur en liant.Les différentes méthodes utilisées ont révélé des facettes particulières de l'étude de traitement des sols fins. Principalement, nous avons noté que les informations apportées par les observations au Microscope Electronique à Balayage, les analyses thermiques et les analyses de Diffraction aux Rayons X ont permis de compléter l’analyse des résultats géotechniques. En somme, les méthodes de caractérisation géotechnique permettent d’avoir une idée générale du potentiel de gonflement, mais pour les études d’envergure, la réalisation d’études microscopiques est primordiale. / To help reduce the problems caused by phenomena due to the shrink-swell soil in the depression of the Lama in southern Benin, we have undertaken research in order to control the behavior of these soils. Six soil samples, including four clay from this area were taken. Different types of tests were performed: a macroscopic characterization concerning mainly mechanical and geotechnical properties and microscopic tests taking into account the chemical, thermal, microstructural and mineralogical analysis. The soils studied consist of different clay minerals. The fibrous structure is at the origin of a particular macroscopic behavior detected by the free swell test. The tests confirmed the potential for swelling and shrinking of some soils that are causing heavy damage.Three soils treated with different contents at Binder Hydraulic Road, were subjected to several tests. The results show that these soils are distinguished by the acquired mechanical performance and may be used at different levels of the floor according to binder content.Also, the different methods revealed specific facets of fine soil treatment study. Mainly, we noted that the information provided by the observations scanning electron microscope, thermal analysis and the analysis of diffraction X-Ray are very important and helped complete the analysis of geotechnical results for soil treatment. In sum, geotechnical characterization methods used to get a general idea of the swelling potential, but for large-scale studies, conducting microscopic studies is paramount.

A series of binuclear coordination complexes of 4-(2′-pyrimidal)-1,2,3,5-dithiadiazolyl and its selenium analogue have been prepared to examine their structural and magnetic properties. The zinc(II) coordination complex is the first example of a DTDA radical ligand N-coordinated to a diamagnetic metal center. The magnetic properties reveal that it exhibits Curie behaviour and can be used as a benchmark to compare the analogous coordination complexes which possess paramagnetic metal ions. The nickel(II) coordination complex of the selenium containing radical pymDSDA was shown to dimerize in the solid state and is the only binuclear complex thus far that has done so. The manganese(II) complex of pymDSDA is by far the most interesting and is isomorphous to the DTDA analogue. For both complexes, one of the two molecules in the asymmetric unit form chains in the solid state joined by intermolecular contacts between a sulfur or selenium atom from the radical, and an oxygen atom coordinated to a neighbouring molecule. This feature gives rise to a ground state spin greater than that of an individual binuclear coordination complex. The radical ligand is however disordered in the solid state and so these random chain lengths are dependent on the orientation of the ligands in adjacent complexes. The 1,2,3-DTA species examined herein are related to the 4,5-dioxo-4,5-dihydronaphtho[1,2-d][1,2,3]dithiazolyl radical and the related protonated species 4-hydroxy-5H-naphtho[1,2-d][1,2,3]dithiazol-5-one. The proton from this latter compound has shown that it can be substituted with alkyl groups and this was achieved using acetyl chloride to place an acetyl group in this position. The above radical did not exhibit the strong donor properties required for metal coordination and preliminary investigations of the radical dianionic suggest that it is chemically irreversible by cyclic voltametry. The acetyl group unfortunately did not provide the chemically reversibility of interest although has established a potential route toward the substitution chemistry of this compound. The other 1,2,3-DTA compounds discussed herein are not complete, although the data acquired on the precursor compounds leading up to the radical will be discussed.

Selective oxidation and sulfation roasting of nickel concentrate followed by leaching was investigated as a novel route for nickel production. In the oxidation roasting stage, the iron species in the nickel concentrate was preferentially oxidized to form iron oxides, leaving non-ferrous metals (Ni, Cu, Co) as sulfides. The roasted product was then sulfation roasted to convert the sulfides of the latter metals into water-soluble sulfates. The sulfates were then leached into solution for further recovery and separation from iron oxides. The oxidation of nickel concentrate was firstly studied by means of thermogravimetric and differential thermal analysis over a wide temperature range. A reaction scheme was deduced, in which preferential oxidation of iron sulfide species occurred over a wide temperature range up to about 700 ºC, forming a Ni1-xS core with iron oxide shell. A batch fluidized bed roaster was then constructed to study the oxidation and sulfation roasting of nickel sulfide concentrate. Oxidation roasting tests were carried out at temperatures between 650 °C and 775 °C. It was found that low temperatures (e.g. 650 °C) are favorable for the preferential oxidation of iron sulfide species while minimizing the formation of nickeliferous oxides, i.e. trevorite and NiO. Several parameters were varied in the sulfation roasting experiments, including the sulfation gas flowrate, sulfation roasting temperature, the addition of Na2SO4, sulfation roasting time, and the oxidation roasting temperature. Under optimized conditions of sulfation gas composition (95% air, 5% SO2), temperature (700 °C), Na2SO4 addition (10 wt%) and time (150 min), the conversions to sulfates were 79% Ni, 91% Cu, and 91% Co. Only 5% Fe forms water-soluble sulfate. The residue from the leaching of calcine in water contained 49% Fe and 10% Ni, which is a suitable feedstock for the production of ferronickel alloys. Therefore, further studies were also conducted to evaluate the reduction behavior of the residue with CO, H2 and graphite.