Gamma decays from high-spin states in the A=51 mirror-pair "'Mn and "Fe, and the A=53 mirror pair 53Fe and 53 Co have been observed up to, and in one nucleus beyond, the fä band terminating states. For "Fe and 53Co, this represents the first observation of states of this type. The nuclei were studied in two GAMMASPHERE experiments with the addition of the FRAGMENT MASS ANALYSER recoil separator and an ion chamber at Argonne National Laboratory in Chicago, Illinois; and the MICROBALL light charged particle detector and the NEUTRON SHELL neutron detector system at Lawrence Berkeley National Laboratory in Berkeley, California. The observation of these isobaric analogue states allowed a detailed comparison of the level energies in each mirror pair. The mirror nuclei have the same mass number, but differing numbers of protons and neutrons. Thus, any difference in excitation energies can be interpreted as being due mainly to the Coulomb interaction, leading to a Coulomb Energy Difference (CED) plot as a function of angular momentum. The changes of the CED with spin have been interpreted in terms of the spatial arrangement of the valence protons, from rotational alignments and the effects of proton-proton recoupling. The observed level energies and the CED have been compared with the results of full pf shell-model calculations, with the Coulomb interaction included via the Coulomb Matrix Elements (CME). This comparison has allowed a detailed understanding of the microscopic mechanisms behind the changes in the CED. The CME were investigated in a fit to the A=53 CED, which revealed an anomalously high and counter-intuitive J=2 component. Extensive results from the study of these CME have been presented, including their role in the evolution of the CED, the physical meaning of the matrix elements themselves, and in particular the origin of the J=2 anomaly.

The work described in this thesis is principally concerned with the measurement of the anharmonicity associated with 'isolated' CH stretching frequencies, and the prediction of individual bond dissociation energies from these values. In addition, CHC1F₂ was the subject of an extended anharmonic vibrational analysis, and CHD₂C1 of a similar vibration-rotation one. In the first of these studies, the IR gas phase spectra of the two isotopic species: CH³⁵C1F₂ and CH³⁷C1F₂, were recorded in the range 15000 - 300 cm^-1. The frequencies of all fundamental vibrations have been accurately determined and analysis of the 800 cm^-1 region Fermi resonance dyad between v4 and 2v6 by the method of isotope shifts yielded an initial estimate of the k₄₆₆ potential energy term. This value enabled the complex pattern of 'hot' bands observed here and in the 1200, 1400, 1600 and 2000 cm^-1 regions, where related Fermi resonances occur, to be analysed, yielding several X<i>ij</i> (i,j = 4,5,6,9) values for both isotopic species. An initial refinement calculation on the data for the ³⁵C1 species from these regions resulted in more accurate X_ij values and a superior estimate of K₄₆₆. A subsequent refinement using data up to 10000 cm^-1 for the vibrational modes v1, v4, and v6 enabled further X_ij (i,j = 1,4,6) values to be determined and several features associated with the CH stretching overtones to be successfully explained. However, the unexpected doublet observed in the region of the CH stretching fundamental could not be unambiguously assigned beyond that one component results from a 'hot' transition. Finally, several more X_ij values were determined from the many overtone and combination bands of other vibrational modes observed in this study, thus defining in total 32 of the 45 anharmonicity constants for this molecule. Secondly, the CH stretching and CH bending modes, their overtones and combinations, in a series of tri-halogenated methanes were studied. The observed spectral features of interests were explained by application of simple second order perturbation theory. However, this approach failed to account for the spectra above approximately 10000 cm^-1 at which point it apparently becomes necessary to apply first order perturbation theory. During the course of this study several ωi and X_ij values were determined. In addition, the inclusion of terms of the type ωey_evi + 1/2)³ when treating an 'isolated' CH bond in a polyatomic molecule as a simple diatomic was investigated. In the next two groups of studies the technique of partial deuteration was employed in order to obtain information on individual CH bond strengths in methyl groups. Firstly, some molecules having symmetrical methyl groups are discussed, specifically CHD₂X (X = C1, Br, I). For the bromide and the iodide the CH stretching mode, v1, and its first two overtones were recorded whilst the entire spectrum of the chloride in the region 12000 - 400 cm^-1 was observed. The bands of these compounds are amenable to both rotational and vibrational analysis in many instances. Thus, for each molecule a value of A_o was determined along with the anharmonicity constant X₁₁. In CHD₂C1 the analysis led to a number of harmonic frequencies, ωi.

A novel x-ray anode for electron spectroscopy is investigated for application in the surface analysis field, monochromatic Ag Lalpha (hnu =2984. 3eV), its energy being capable of exciting 1s electrons up to chlorine in the periodic table. Resolution available with this source is satisfactory, with a limitation of approximately 1. 3eV. An increase in sensitivity is achieved for those peaks in the range 1500-3000BE, whilst there is no serious reduction within the conventional XPS energy range. The agreement between experimental sensitivity factors and theoretical cross-section values is good, allowing the transmission function for the VG ESCA3 Mkll spectrometer to be confirmed constant from 0-3000eV. A comprehensive investigation of the LEG51 electron flood gun preceded its successful application for the charge neutralisation of insulating materials. This allowed the application of this source to such materials as chlorides, pertinent to the breakdown in passivity on stainless steels, and silicon compounds, involving thermal oxides on silicon of interest to the microchip industry, zeolites for catalysis in the petrochemical industry and siloxane copolymers for the opthalmic industry. The ability to excite the 1s orbital, together with the 2p and KLL Auger lines, affords calculation of Auger parameters and extra-atomic relaxation energies for the accurate description of the chemical environment of a particular chemical species. A method for internal energy referencing is investigated, involving the vaccum-deposition of Au, Cu and Pt metals. This allows the measurement of photoelectron binding energies to an accuracy of +/-0.1-0.2eV for insulating materials, when referenced to the vacuum level.

Chemistry of intermetallic bonded diamond is studied. The impact resistance and energies of intermetallic bonded diamond is compared to current poly crystalline diamond compacts. IBD’s are found to have high standards of hardness and have more impact energies absorbed. Intermetallic bonded diamond composite comprises of diamond particles dispersed in Tungsten carbide using Nickel aluminide (Ni3Al) as binder. In previous research conducted on IBD’s, diamonds are successfully dispersed in intermetallic alloy of nickel aluminide and processed at 1350°C such that diamond particles remain intact without forming graphite. Composites are formed by milling, pressing the intermetallic binder and diamond particles and sintering at high temperature conditions.

Afin de lutter contre le changement climatique et de préserver les ressources naturelles, de nombreux pays ont mis en place des politiques plus ou moins ambitieuses de développement des énergies renouvelables électriques à court et moyen terme, tandis que, en parallèle, des scénarii de prospective à long terme envisagent un approvisionnement électrique majoritairement d'origine renouvelable. Certaines de ces énergies sont intermittentes et non contrôlables et, du fait des faibles économies d'échelle dont elles bénéficient, peuvent être développées de manière décentralisée, intégrées au bâtiment et raccordées au réseau de distribution, à l'opposé des moyens de production actuels. Concomitamment, les pointes de consommation augmentent à un rythme soutenu et obligent les gestionnaires de réseaux et les producteurs/fournisseurs à toujours plus d'investissements dans des moyens de production et de transport qui ne seront utilisés que pendant un faible nombre d'heures par an.Les changements décrits ci-dessus vont avoir un impact sur les trois grands objectifs de la planification et de la gestion du système électrique : minimiser le coût global, assurer la sûreté de l'approvisionnement et garantir la qualité de la fourniture. Si on analyse le fonctionnement actuel du système, les transformations à venir et les possibilités offertes par l'intégration de solutions de contrôle et de gestion (compteurs électriques communicants, transformateurs régleur en charge, onduleurs PV avec gestion de réactif, stockages, etc.) au réseau de distribution, il est possible de mettre en évidence trois grands domaines d'application - et donc de valorisation - pour celles-ci. Il s'agit du déplacement temporel d'énergie, de la fourniture de services auxiliaires (régulation et suivi de charge, réserve ou gestion de tension, par exemple) et de l'optimisation de la planification et de la gestion du réseau (évitement et/ou retardement d'investissement).Cependant, l'ensemble des procédures et méthodes de planification et d'opération actuel est basé sur l'hypothèse d'une production centralisée et d'un réseau de distribution passif. Dans ce contexte, cette thèse contribue au développement d'une méthode de simulation d'un réseau de distribution actif en proposant trois avancées: une méthode de décomposition-coordination permettant la simulation intégrée du système centralisé et du réseau de distribution, un algorithme de résolution du problème des flux optimaux dans le réseau de distribution et un critère de criticité diminuant les besoins en capacité de calcul de la simulation si elle est employé dans un cadre de planification. / Many countries have set up mechanism support in favor of renewable energy development at a short or long term, while, in parallel, long-term scenarios of predominantly renewable energy provisioning are studied. Some of these energies are intermittent and non-dispatchable and, due to the low economies of scale they exhibit, can be deployed in a decentralized manner, integrated in buildings and connected to the distribution system.However, the methods and tools currently used to plan and operate the power system rely on hypothesis of centralized generation and passive distribution network. In this context, this thesis contributes to the development of a method aimed at simulated an active distribution network by proposing three novel approaches: a decomposition and coordination method allowing the integrated simulation of the centralized power system and the active distribution network, an algorithm to solve the single-stage optimal power flow in the distribution system as well as two criticality criteria allowing to decrease the computational burden of the simulation when it is used for planning purposes.

No description available.

Made available in DSpace on 2014-06-11T19:30:09Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-05Bitstream added on 2014-06-13T20:00:01Z : No. of bitstreams: 1 rodriguez_cjc_me_guara.pdf: 4550695 bytes, checksum: 39fdcc0a3d1ecf7ac3bdba90c51c9d49 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Após as crises do petróleo de 1973 e de 1979, notou-se um efeito nocivo dos elevados custos e contínuo aumento dos preços do petróleo, razão pela qual aumentou o interesse pelas fontes de energias renováveis, amplamente disponíveis nos países em desenvolvimento. Em todo o mundo, tornaram-se objetivos prioritários de se economizar energia e buscar tecnologias racionais, levando-se sempre em consideração os efeitos relacionados ao meio ambiente. Por outro lado, a escassez iminente dos combustíveis fósseis tem exigido da humanidade o uso racional de energia primária e como conseqüência, novas plantas em versões tecnológicas mais desenvolvidas têm sido concebidas visando sempre o aumento da eficiência energética. Neste contexto, destacam-se as tecnologias de gaseificação de madeira, que consistem em técnicas de conversão da biomassa em gás combustível. O objetivo principal deste trabalho é o desenvolvimento e a demonstração de uma metodologia de dimensionamento de um gaseificador de leito fixo tipo Downdraft para uma alimentação de 100 kg/h de biomassa lignocelulósica. Avalia-se e escolhe-se os diversos equipamentos e acessórios necessários para a limpeza e acondicionamento do gás combustível para a alimentação de um motor de combustão interna. A análise técnica inclui além dos parâmetros construtivos específicos do gaseificador, o balanço de massa, de energia, e a determinação das eficiências, tanto para a eficiência a frio como para a eficiência a quente do gaseificador. A análise econômica inclui uma avaliação e obtenção dos custos tanto do gaseificador como do Motor de Combustão Interna acoplado, os custos dos equipamentos e acessórios da zona de gaseificação, os custos operacionais e os custos da instalação e amortização do projeto. / After the oil crisis of 1973 and 1979, an effect of the increase costs and continuously increment of the oil prices was noted. For this reason, the interest for renewable energies sources widely available in developing countries was increased. The governments have formulated main objectives for energy savings and search for friendly technologies, taking into account the effects related with the environment. The new plants with improved technology have been conceived always taking into account energy savings and efficiency improvement. In this context, biomass gasification technologies are important, since they consist in techniques of parallel production of electricity and heat from just one fuel. The main objective of this work is to develop and to demonstrate a scale up methodology for the construction of a bed fix downdraft gasifier with a 100 kg/h supply using as raw material lignocelulosic biomass. It will be evaluated and analytically chosen the necessary accessories and equipments for the cleaning and preparation of the biomass fuel gas, then this gas will be used in a internal combustion engine. The technical analysis includes in addition to the constructive specifics parameters, the balance of mass, balance of energy and determination of the efficiencies for thermal generation and power generation (hot efficiencies or cold efficiencies, respectively. The economic analysis includes cost evaluation of the gasifier, internal combustion engine, equipment and accessories of the gasification zone, operational and installation and amortization of the project.

No description available.

Meter a lapse of about five years the experimental attack on the secrets of the otomio nucleus hau begun again. The num her of ocientistr3 now engaged in this work and the number of particle decelerators which exact or are under coaztruction are very much greater than at any other p rcviouo time. 1ý Since the gar there have emerged several new promising methods of accelerating particles to very high enargiea. In every case the size, expense and time of eonmtruction of the o, pnratu3 are very 1nrge. The machine which is most suitable for accelerating particles to the highest energies is the proton synchrotron. Until recently this development wes confined to the BirminChe. n University, whore a machine designed to' accelerate protons to 109 eV (and possibly deuterons and of -particles to "6x 109 aV and 109 eV reapoctinely) in v2cll under construction. It id with the theory and construction of such an accelerator that this thesis is mainly concerned (Chapters III, IV and V). While building ouch a complicated picco of apparatus it in bf course essential to appreciate its likely uses. Since the proton synchrotron will be capable of deliýrering pcrtiolea over a very viide ranee of energies (protons from 2 ý- 1,000 MoV) the possible experim©nta are likely to include nearly all thoac cihich can be performed with arty accelerator. Naturally attention will be confined largely to the very high energy region.

No description available.