Thèses sur le sujet « Metallic wares »

The use of patterned metallic surfaces for the control of the transmission of microwave radiation has been reinvigorated in recent years due to the success and interest in metamaterial research. These metallic periodic structures, commonly referred to as frequency selective screens (FSSs), allow responses to be tailored according to the geometry of the metallic structure as opposed to the material composition. A consequence of the presence of a metallic corrugation is the possible excitation of surfaces waves (commonly referred to as surface plasmon polaritons at visible frequencies). Surface waves can be utilised to achieve further control of the transmission properties of a structure. In this thesis several highly original metallic structures are investigated which use FSS and surface wave concepts. These structures exhibit interesting and previously unexplained transmission behaviour. The experimental chapters within this thesis are divided into two areas. The first three experimental chapters (4-6) present original investigations into the excitation of diffractively coupled surface waves on metallic hole/patch arrays and their role in the enhanced transmission/reflection of microwave radiation. The importance of metallic connectivity within arrays is highlighted through measurements of the metallic filling fraction dependence on the transmission properties of regular periodic and random arrays. The last two experimental chapters (7-8) contain investigations into the transmission properties of two novel resonant cavities. The structure studied in chapter 7 provides a mechanism for remarkably enhanced microwave transmission on resonance through an otherwise opaque continuous thin metal film. The second resonant cavity structure in chapter 8 uses a resonant array of metallic crosses to form a ‘resonant mirror’ Fabry-Perot cavity. These resonant FSSs exhibit a frequency dependent transmission/reflection and phase response thus producing an interesting series of modes which have very different properties to those supported by a non-resonant mirror etalon.

The equations tor the propagation of Electromagnetic and Optical waves in tapered fibers and metallic waveguides are derived. Solutions are derived for the displacement of the beam from the waveguide axis as a function of distance along the axis, and also tor the beam width as a function of distance. These equations are solved numerically for a variety of tapered guides. Experiments are conducted which verify the theoretical results.

Abstract: This master thesis presents an archaeological study of the Metallic Ware from the Tell elFar'ah North (West Bank) archaeological site, on ceramic fragments dating from the Early Bronze Age II (3000 - 2700 BC). Optical Microscopy and X-ray powder diffraction showed a Metallic Ware different from the North Canaanite one, produced with a calcareous clay with dominant quartz, common fragments of sedimentary and siliceous rocks, few feldspars, and nodules of iron oxides. The Metallic Ware quality was achieved by high firing temperature between 850-900 ºC. Tell el-Far'ah North was hypothesized as one of the main production centres of Metallic Ware.

A general recursion method (method of adlayers) for calculating the exact Green function in an arbitrary overlayer is developed. The method as presented applies to an s-band tight-binding Hamiltonian with hopping between nearest-neighbours only. The general.isation of the method to a multi-orbital band structure is described. The overlayer we consider is deposited above the (100) surface of a simple cubic semi-infinite nonmagnetic metallic substrate occupying the half-space z < O. The aim of the present thesis is twofold: firstly, the ground state of a ferromagnetic overlayer is investigated. In particular, the local densities of states (LOOS) of an overlayer are calculated using the method of adlayers. The method of adlayers is very simple, computationally stable and extremely accurate. The numerical results for the LOOS and the Hartree-Fock (HF) occupation numbers of a single-adlayer and a seven-adlayer overlayer are presented. The surface and bulk DOSs for an overlayer of seven atomic planes are compared. The presence of an adlayer may induce surface states if a strong enough perturbation occurs at the surface. Such surface states are automatically included in our method of adlayers. Secondly, spin waves in a transition metal overlayer are investigated within the framework of the itinerant theory of magnetism. The overlayer is modelled by a single-orbital tight-binding band with a strong intra-atomic repulsion U (one band Hubbard model). All the matrix elements of the HF dynamic unenhanced susceptibility in the overlayer are computed from the HF one-electron Green functions. Spin waves are then poles of the full dynamic enhanced susceptibility which is determined in the random phase approximation (RPA). It is demonstrated that a very high accuracy in solving the HF ground state is needed to determine correctly spin wave modes. When this requirement is fulfilled, the Goldstone theorem at zero wavevector and zero frequency is very well satisfied. Numerical results for the spin wave spectra of a single-adlayer are presented for a range of values of U. Spin wave energies for a single-adlayer, for an unsupported layer and the exchange stiffness constant 0 of an unsupported layer are compared. Finally, all the computed spin wave branches of an overlayer of seven atomic planes are presented and discussed. The disappearance of spin waves in the Stoner continuum is illustrated and the possibility that a surface spin wave mode might occur is briefly discussed.

In this thesis I present experimental measurements on a number of different quasi-one and quasi-two-dimensional metallic crystal systems susceptible to density-wave formation. I outline the discovery of a density-wave superstructure found via X-ray diffraction measurements in the quasi-two-dimensional Na2Ti2As2O and Na2Ti2Sb2O compounds. Na2Ti2Sb2O and Na2Ti2As2O are members of the Ti-based oxy-pnictides a group of compounds which exhibit complex phase diagrams and share structural similarities with the high temperature superconductors. Temperature-dependent X-ray diffraction measurements confirmed the superstructure in both materials to be concomitant with transitions seen in resistivity and magnetic data. The observation of the superstructure combined with results from other experimental techniques demonstrated the transition to be a charge-density-wave. I also present results on a series of intercalated charge-density-wave compounds NixZrTe3. NixZrTe3 was measured using X-ray diffraction and ARPES to investigate the effects of chemical pressure on charge-density-wave formation. The transition temperature for density-wave formation in this series of compounds had been previously shown to vary as a result of Ni-content. X-ray diffraction measurements on the series revealed no changes in the wavevector of the associated superstructure modulation across the series. However ARPES measurements on NixZrTe3 showed subtle changes in the binding energy of the one-dimensional band associated with the charge-density-wave thought to be a result of the Ni-intercalation. Through a combination of XPS, EDX and ARPES measurements the Ni-content in these crystals was deduced to be much lower than growth parameters suggested. Finally I describe the construction and testing of a straining device designed specifically for use with X-ray synchrotron type measurements. The straining device was successfully tested at the I16 beamline at the Diamond Light Source and shown to induce dynamic strain in a test sample of M2Mo6Se6. Further testing at the ID28 beamline at the ESRF revealed that the strain induced in a M2Mo6Se6 was significant and resulted in a change in the lattice dynamics of the material.

The development of protective structures to resist highly energetic dynamic loads such as impact and blasts is a widely researched domain with many civil and military-related applications. With increased emphasis on material, structural and geometrical optimization, a special class of multi-material systems called functionally graded materials have gained significant interest in this field of research. This thesis investigates the performance of a novel multi-metallic system, where the metals are functionally graded in reducing order of their impedance. The scope of the thesis is limited to dynamic loads that generate high strain rates in metals. Under such conditions, metals behave predominantly in a uniaxial state of strain, where the analysis must consider the propagation of stress waves. These stress waves can be in the form of elastic, plastic or shock waves. Hence, Impedance - which is the product of volumetric mass density and wave velocity - was chosen as the function, as it plays a governing role in the propagation of elastic, plastic and shock waves. The main objective of the thesis is to investigate the possibility of attenuating stress waves through the proposed system and a comprehensive experimental, analytical and numerical investigation is carried out to achieve this. The experiments consist of low velocity and high-velocity impact tests and are carried out using a single-stage gas gun test setup, as well as near-field blast trials. The performance of the impedance-graded combinations of steel-titanium, steel-aluminium, steel-titanium-aluminium and steel-brass-aluminium are compared against a monolithic steel configuration. Numerical simulation of these events is conducted using the non-linear finite element software LS-DYNA. One-directional and two-directional wave propagation models with a Lagrangian mesh discretisation are used for the impact events to accurately capture the propagation of stress waves through the solids. In addition to the attenuation of stress waves, the experiments identified the potential of this system in minimizing common failure types under dynamic loads, such as debonding, spalling and scabbing. The reasons behind these findings were explained by referring to the generation of compressive and tensile stresses due to the propagation, transmission and reflection of stress waves. In conclusion, this thesis provides a comprehensive framework to design and apply impedance-graded multi-metallic systems in the field of protective structures.

Thesis (M.S.)--University of Kentucky, 2006.
Title from document title page (viewed on June 1, 2006). Document formatted into pages; contains ix, 94 p. : ill. (some col.). Includes abstract and vita. Includes bibliographical references (p. 91-93).

Cette thèse présente les contributions de l'auteur au domaine des ondes non-diffractives. Essentiellement, les ondes non diffractives sont des faisceaux électromagnétiques qui rayonnent une énergie localisée avec une variété d'applications pratiques potentielles. Le travail présenté dans cette thèse peut être divisé en deux parties. Dans la première partie, un nouveau concept de synthèse de lanceurs de faisceaux de Bessel/ondes X à profil spline a été proposé. Tout d'abord, un outil basé sur l'adaptation de mode est présenté. L'outil est capable d'évaluer les paramètres S, les diagrammes de rayonnement en champ proche et lointain de structures métalliques à symétrie azimutale. Ensuite, des lanceurs métalliques à faisceau de Bessel/ à impulsion sont synthétisés à l'aide de cet outil ad hoc. Le concept a été validé expérimentalement en fabriquant et en mesurant un lanceur pour fonctionner dans une gamme de fréquences de 75 à 105 GHz. Le lanceur est la première démonstration d'un lanceur d'ondes X à de telles fréquences. Dans la deuxième partie, nous avons étudié l'utilisation d'ondes non diffractives pour le transfert d'énergie sans fil. Tout d'abord, l'utilisation de faisceaux de Bessel-Gauss pour le WPT est étudiée. Les performances supérieures des faisceaux de Bessel-Gauss par rapport aux faisceaux de Bessel sont démontrées. Un lanceur Bessel-Gauss a été conçu pour valider cette affirmation. Le coefficient de transfert de puissance du lanceur dépasse 50 % pour les distances dépassant sa portée de non diffraction
This thesis present the author’s contributions to the field of non-diffractive waves. Essentially, non-diffractive waves are electromagnetic beams that radiate localized energy with a variety of potential practical applications. The work presented in this thesis can be divided into two parts. In the first part, a novel concept of synthesizing metallic spline profiled Bessel beam/X-wave launchers has been proposed. First, an ad-hoc tool based on mode matching is presented. The tool is capable of evaluating the S parameters, near-, and far-field radiation patterns of metallic structures with azimuthal symmetry. Then, metallic Bessel beam/X-wave launchers are synthesized using the ad-hoc tool. The concept has been experimentally validated by manufacturing and measuring an X-wave launcher operating in a 75-105 GHz frequency range. The fabricated launcher is the first experimental demonstration of an X-wave launcher at such frequencies. In the second part, we have investigated the use of non-diffractive waves for wireless power transfer. First, the use of Bessel-Gauss beams for WPT is investigated. The superior performance of Bessel-Gauss beams compared to Bessel beams is demonstrated. A Bessel-Gauss launcher has been designed for validating this claim. The power transfer coefficient of the launcher exceeds 50% for distances exceeding its non-diffractive range

THESIS ORGANISATION This thesis is organised into nine chapters that include seven international and national publications (six accepted and one submitted for publication). The initial overview chapter outlines the justification and direction for this thesis. With the exception of chapter 8 (accepted for publication on the 1st May 2005); all chapters are exact duplicates of published articles in international and national refereed journals (chapters 2 to 7). The initial chapters (2 and 3) presents research findings using a marine fish species, mullet (Mugil cephalus), to measure trace metal bioavailability in Lake Macquarie, NSW Australia. While subsequent chapters (4 to 8) are presenting research under taken to improve the understanding of arsenic cycling in marine and estuarine environments. The final chapter (chapter 9) is a synopsis of the major findings presented in this thesis. Due to the publication nature of this thesis, an unavoidable degree of replication exists within chapters (publications).

Aquesta tesi te com a objecte l’estudi de l’estructura electrònica de metalls de baixa dimensionalitat tant en la forma de monocapes com en el bulk. Aquest tipus de metalls sovint presenten inestabilitats electròniques del tipus ona de densitat de càrrega (CDW) o de espí (SDW). La major part dels esquemes teòrics utilitzats per entendre l’origen d’aquestes inestabilitats es basen en la noció de nesting de la superfície de Fermi. Tanmateix, si es considera en detall la informació experimental, en un nombre important dels materials que exhibeixen aquestes inestabilitats no es gens clar que aquest tipus de mecanisme sigui apropiat. L’objecte d’aquest treball es el de reconsiderar críticament aquesta situació, basant-se en el càlcul precís per mètodes de primers principis DFT de la funció de resposta de Lindhard i/o l’estructura de bandes de fonons. Hem estudiat un nombre considerable de materials d’aquest tipus: dicalcogenurs de metalls de transició (TiSe2, TiTe2 i NbSe2), òxids i bronzes ( bronze blau, bronzes monofosfats de tungstè, perovskites laminars AnBnO3n+2, amb B: Nb, Ti, fases de Magnéli com Mo4O11 i Mo8O23), tricalgogenurs (NbS3, NbSe3, TaS3, ZrTe3) i tetracalcogenurs de metalls de transició (TaTe4, (TaSe2)4I), conductors moleculars com les sals de Bechgaard (TMTSF)2X amb X = ClO4, NO3, PF6 ) i compostos intermetàl·lics de terres rares (LaAgSb2). En aquest document exposem en detall els nostres resultats per sis d’aquests materials: TiSe2, TiTe2, NbSe2, els bronzes blaus, les salts de Bechgaard i TaTe4. Com a resultat d’aquest treball hem pogut demostrar que: 1) El mecanisme de formació de CDW a TiSe2, TiTe2, NbSe2 i TaTe4 es degut a una inestabilitat de fonons que no te rés a veure amb el nesting de la superfície de Fermi; 2) fins a sis diferents estructures poden coexistir en l’estat CDW del NbSe2; 3) en el cas del bronze blau, es pot explicar la seva transició de Peierls sobre la base d’un mecanisme basat en un acoblament electrò-fonò feble dins l’aproximació adiabàtica i 4) la funció de resposta de Lindhard de les sals de Bechgaard canvia considerablement amb la temperatura I aquests canvis estan clarament associats amb variacións de la dimensionalitat del gas d’electrons.
This thesis deals with the electronic structure of low dimensional metals in the form of either single layers or bulk. Low dimensional metals often exhibit electronic instabilities like charge or spin density waves. A central role in most of the theoretical approaches to understand these instabilities is played by the notion of Fermi surface nesting. Very often this is considered to be the driving force of these instabilities. Yet a careful examination of the experimental information casts strong doubts about the appropriateness of such notion for a considerable number of these conductors. The object of the present thesis is an appraisal of this situation based on the calculation of the Lidhard response function as well as the phonon band structure for a series of low dimensional conductors based on accurate first-principles DFT calculations. Altogether we have studied from the first principles calculations standpoint the following classes of materials: transition metal dichalcogenides (TiSe2, TiTe2 and NbSe2), oxides (blue bronze, monophosphate tungsten bronzes, layered perovskite-related AnBnO3n+2 niobates and titanates, Magnèli phases Mo4O11 and Mo8O23), transition metal trichalcogenides (NbS3, NbSe3, TaS3, ZrTe3) and tetrachalcogenides (TaTe4, (TaSe2)4I), Bechgaards salts ( (TMTSF)2X with X = ClO4, NO3, PF6) and rare earth intermetallics (LaAgSb2) . In this document we report the results for six of these materials: TiSe2, TiTe2, NbSe2, the potassium blue bronze, the Bechgaard salts and TaTe4. As a result of this work, we have been able to show that: 1) The CDW mechanism in TiSe2, TiTe2, NbSe2 and TaTe4 is a phonon mediated mechanism and completely unrelated to the Fermi surface nesting mechanism; 2) 6 different structure can coexist in the CDW state of NbSe2; 3) in the blue bronze the Peierls transition can be well accounted for by the weak electron-phonon coupling theory in the adiabatic approximation. 4) that in the Bechgaard salts the Lindhard response is found to change considerably with temperature and these changes are clearly associated with dimensional crossovers.

Le modèle du jellium est l'un des modèles fondamentaux de la matière condensée.Il est constitué d'un ensemble d'électrons et d'un fond uniforme qui assure la neutralité globale.À température nulle et sans champ extérieur, la densité électronique est le seul paramètre du système.Malgré la simplicité de ce modèle, l'état fondamental du jellium en fonction de la densité reste un problème ouvert.Nous avons étudié le modèle du jellium à 2 et 3 dimensions dans l'approximation de Hartree-Fock par une méthode numérique de descente.En utilisant des états périodiques, le nombre d’inconnues est grandement réduit et le nombre d’électrons peut atteindre le million.À type de réseau et polarisation fixés, nous montrons que le système forme un cristal de Wigner à basse densité puis, au dessus d'une densité de transition, occupe des états «métalliques» caractérisés par une structure cristalline avec une maille plus petite que celle du cristal de Wigner.Les états métalliques interpolent entre le cristal de Wigner et le gaz de Fermi, ce dernier n'étant retrouvé qu'à densité infinie.Ce comportement se retrouve à deux et trois dimensions, pour un gaz polarisé et non polarisé, et pour les différents type de réseaux considérés dans nos travaux.Le diagramme de phase à deux ou trois dimensions est alors très riche et comprend à basse densité diverses phases «cristal de Wigner» avec des symétries et polarisations différentes.À haute densité, les états métalliques non-polarisées déstabilisent le cristal de Wigner et le gaz de Fermi. Ces états métalliques s’interprètent comme une superposition d’ondes de densité de spin, prédite par Overhauser en 1962
The jellium model is a fundamental model in condensed matter. It is formed by a set of electrons and a uniform background insuring global neutrality. At zero temperature and without external field, the ground-state depends only on the electronic density. Despite its simplicity, the jellium ground-state is still an open problem. We studied the jellium model in 2 and 3 dimensions within the Hartree-Fock approximation using a numerical descent method. Assuming periodic states, we greatly reduce the number of unknowns and the system may contain up to one million of electrons. At fixed lattice symmetry and polarization, the ground-state is a Wigner crystal at low density, and a «metallic state» above a critical density value. These metallic states are crystals with a lattice constant smaller than in Wigner phase, and interpolate between the latter and the Fermi gas. The metallic states exists in two and three dimensions, for a polarized and unpolarized gas, and for various lattice symmetries. Therefore, the jellium phase diagram at zero temperature is rich : it contains several Wigner crystal phases at low density, polarized and unpolarized, and an unpolarized metallic state at high density. These states are well described by a superposition of spin-density waves, as predicted by Overhauser in 1962

Les mousses métalliques ont connu un essor important durant les dernières décennies. Leur capacité à supporter de très larges niveaux de déformation tout en transmettant de faibles contraintes les rend particulièrement adaptés à des solutions d'absorption d'énergie ou de protection contre des sollicitations intenses.Le comportement dynamique de ce type de matériau peut être influencé par les effets inertiels au niveau des parois ou des ligaments constituant son squelette (micro-inertie). Un modèle de comportement à base micromécanique a été développé pour prendre en compte les effets micro-inertiels sur le comportement macroscopique de mousses à porosités fermées. Le modèle proposé repose sur la procédure d'homogénéisation dynamique introduite par Molinari et Mercier (2001). Par cette approche, les effets micro-inertiels apparaissent sous la forme d'un terme supplémentaire dans le tenseur des contraintes, appelé contrainte dynamique. À partir de comparaisons avec des données extraites de la littérature, il est ainsi démontré qu'inclure les effets micro-inertiels permet d'obtenir une meilleure description de la réponse des mousses sous choc.L'influence d'une épaisseur de mousse localisée entre un explosif et une enveloppe cylindrique a ensuite été étudiée en suivant deux approches. La première, qui s'appuie sur les travaux de Gurney (1943), repose sur des considérations énergétiques. La seconde méthode permet d'aboutir à une description plus détaillée des tailles et vitesses de fragments. Elle repose sur la combinaison d'un modèle éléments finis pour décrire la propagation de l'onde de choc dans la mousse et l'expansion de l'enveloppe et d'un modèle de fragmentation de type Mott (1947)
Metallic foams have known a growing interest in the last decades. Their ability to undergo very large strains while transmitting only reasonable stress levels makes them particularly suitable for energy absorption applications and protection against intense solicitations. The dynamic behavior of metal foams is linked to inertial effects appearing at the walls and ligaments of the material microstructure (micro-inertia). A constitutive model has been developed to take micro-inertial effects into account when describing the macroscopic behavior of closed-cell foams submitted to dynamic loadings. The proposed approach was developed using the dynamic homogenization procedure introduced by Molinari and Mercier (2001). Within this framework, micro-inertial effects appear as an additional stress term, called dynamic stress. Comparisons with data from literature have showed that including micro-inertia effects allows one to achieve a better description of the foam response under shock loading.The influence of a foam layer placed between an explosive and a cylindrical casing has been investigated by following two approaches. The first one is based on energetic considerations, following the work of Gurney (1943). The second method allows one to obtain a more detailed description of fragment sizes and velocities. It relies on the combined use of a finite element model and a description of the shell fragmentation based on the work of Mott (1947)

Les imidazo[1,2-b]pyrazoles tout comme les imidazo[1,2-a]imidazoles sont des entités présentant diverses applications intéressantes notamment dans le domaine pharmacologique. Cependant, malgré ce potentiel, ces structures hétérobicycliques ont été, jusqu’à ce jour, relativement peu étudiées tant au niveau de leur préparation que de leur fonctionnalisation. De ce fait, ces travaux de thèse ont pour objet la mise au point de nouvelles voies d’accès à ces systèmes bicycliques et ce, au départ de substrats facilement accessibles. Des stratégies de fonctionnalisation de ces charpentes moléculaires ont ensuite été développées dans le but de concevoir des librairies diversifiées de ce type de composés, librairies destinées à être évaluées biologiquement. Les premiers résultats d’évaluation sur des lignées cancéreuses de dérivés imidazo[1,2-b]pyrazoliques sont également présentés
Imidazo[1,2-b]pyrazoles and imidazo[1,2-a]imidazoles are entities with some interesting applications in pharmacology. However, despite this potential, few methods of preparation and direct functionalisation of the heterocyclic moiety have been described. In this context, the overall goal of our research is to develop new routes to these bicyclic systems from readily available starting materials. Strategies of functionalisation of the heterocyclic moiety were then explored in order to design diversified libraries for the evaluation of potential biological activities. Herein, the results of the tests of imidazo[1,2-b]pyrazole series against various cancer lines are reported

Les pyrrolo[2,3-d]pyrimidines, également connues sous le nom de 7-déazapurines, sont une classe importante d’hétérocycliques aromatiques, de par leurs potentiels biologiques (antitumoral, antiinflammatoire, antibactérien, etc.). C’est pourquoi ce squelette a été une source d’intérêt pour les chimistes organiciens. Outre leurs atouts biologiques, ces molécules présentent également de remarquables propriétés physico-chimiques (fluorescence UV), ce qui permet de nouvelles applications en électronique. Bien que ces dernières années, un bon nombre de recherche ont été mises en oeuvre en vue de synthétiser ces molécules, il n’existe encore que peu de méthodes générales pour obtenir des pyrrolo[2,3-d]pyrimidines hautement substituées. Le but de ces travaux de thèse est de développer différentes stratégies régiosélectives et chimiosélectives de synthèse pour accéder à des pyrrolo[2,3-d]pyrimidines diversement substituées et ce, en un minimum d’étapes. Dans un premier temps, il a été synthétisé une famille de 7-méthylpyrrolo[2,3-d]pyrimidines 4,5,6 triarylées notamment via l’utilisation de deux réactions de Suzuki-Miyaura. Pour faire suite, nous avons envisagé la préparation d’une série de pyrrolopyrimidines 2,4,6-triarylées où le motif aromatique de la position 2 est introduit suivant les conditions de Liebeskind-Srogl. Enfin la préparation de pyrrolo[2,3-d]pyrimidines 4-aminées à partir d’alkynylpyrimidines a été mise au point et divers composés de cette famille ont été élaborés
The pyrrolo [2,3-d]pyrimidines, also known as 7-deazapurines, are an important class of aromatic heterocycles by their biological potencial (antitumor, anti-inflammatory, antibacterial, etc.). Therefore, this skeleton is a source of interest for the organic chemists. A part of the biological activity, these compounds present also outstanding physicochemical properties (UV-fluorescence); enabling new applications in electronics. The last few years, a great number of researches have been put in execution with a view to synthesizing these molecules, where still few general methods exist to obtain pyrrolo [2,3-d] pyrimidines highly substituted. The aim of these works of thesis is to develop different regioselective and chemoselective synthetic strategies to accede to pyrrolo [2,3-d]pyrimidines diversely substituted and furthemore in a reduced number of steps. First has been synthesized a family of 4,5,6-triarylated-7-methylpyrrolo[2,3-d]pyrimidines including the use of two Suzuki-Miyaura's reactions. Also we contemplated the preparation of a series of 2,4,6-triarylated pyrrolopyrimidines where the aryl group at the position 2 has been introduced under Liebeskind-Srogl reaction conditions. Finally the preparation of 4-aminated pyrrolo [2,3-d] pyrimidines from alkynylpyrimidines has been fine-tuned and diverse derivative compounds have been synthesized

La adsorció sobre carbó actiu és un tractament habitual para a l'eliminació de metalls contaminants d'afluents aquosos. Amb la finalitat de reduir el cost dels tractament actuals s'està estudiant la utilització d'adsorbents de baix cost com a substituts dels sorbents convencionals que s'utilitzen usualment en els tractaments d'aigües. En aquesta tesi s'ha avaluat la possibilitat d'aprofitar diversos residus vegetals procedents de processos agrícoles o residus industrials, com a sorbents per a l'eliminació de metalls de solucions aquoses. En concret, el treball s'ha centrat en assolir dos grans objectius, primer de tot, conèixer la possibilitat d'utilitzar el pinyol d'oliva com a adsorbent de metalls divalents de solucions aquoses, com són el Cd(II), Cu(II), Ni(II) i Pb(II), i en segon lloc, avaluar la utilització de quatre residus vegetals (escorça de yohimbe, rapa de raïm, suro i pinyol d'oliva) per a l'extracció de Cr(VI) de solucions aquoses i utilitzar el residu vegetal més apropiat com a base per tal d'obtenir un nou sorbent, amb més bona morfologia per ser utilitzat en sistemes d'eliminació de Cr(VI) en continu. Les dades cinètiques d'adsorció es van tractar amb el model cinètic de pseudo-segon ordre, amb el que es van determinar la velocitat inicial d'adsorció dels metalls. Els models d'isotermes d'equilibri de Langmuir i Freundlich es van utilitzar per descriure els equilibris d'adsorció i calcular els paràmetres de les isotermes. En els assajos amb mescles binàries de metalls, els resultats es van tractar amb el model ampliat de Langmuir.
En aquest treball s'ha determinat, primerament, que el pinyol d'oliva és un bon sorbent dels metalls divalents estudiats. S'ha determinat que l'adsorció dels metalls varia amb el pH de la solució i que la presència de sals en la solució provoca una davallada en l'adsorció. També es va determinar la competència en l'adsorció entre els metalls al realitzar assajos en mescles binàries.
Amb els estudis d'extracció de Cr(VI) amb els quatre materials s'ha determinat que aquests vegetals poden adsorbir el Cr(VI) en solució, tot i que la rapa i la yohimbe són els materials que presenten unes capacitats d'adsorció més elevades. Les anàlisis amb espectroscòpia electrònica de Raig-X realitzats en la rapa de raïm i la yohimbe en contacte amb Cr(VI) varen demostrar la presència del metall en els dos estats d'oxidació, Cr(VI) i Cr(III), evidenciant la participació del mecanisme de reducció de Cr(VI) en l'adsorció del metall sobre els materials.
Amb l'encapsulació de la rapa de raïm es va incrementar significativament la capacitat d'adsorció del metall respecta a la seva utilització en la forma original. Les dades experimentals es van tractar amb un model de difusió i es va determinar el coeficient de difusió en l'adsorció en el sorbent amb diferent percentatge de rapa en l'interior.
Finalment s'han realitzat estudis preliminars d'adsorció de crom hexavalent en continu utilitzant columnes de petites dimensions farcides amb el sorbent format per boles de rapa encapsulada en alginat càlcic. En aquests assajos s'ha determinat l'efecte en l'adsorció de metall de diversos paràmetres d'operació, com la concentració inicial de metall, el cabal i l'alçada de llit. El model de transferència de matèria i difusió en columna emprat pel tractament de les dades experimentals va mostrar l'efecte de la concentració inicial i del cabal en els coeficients de difusió i transferència de matèria. El model BDST no va predir correctament el temps de servei en els diferents paràmetres d'operació experimentats a causa de la complexitat del procés d'adsorció. Amb aquests assajos preliminars s'han establert les bases de l'adsorció de Cr(VI) amb el nou sorbent en sistemes en continu amb la finalitat de realitzar estudis posteriors d'eliminació del metall en columnes de majors dimensions.
Adsorption with activated carbon is a usual treatment to remove metals from wastewater. In order to reduce the cost of the treatment, several studies have been carried out to evaluate the use of low cost sorbents as an alternative to conventional sorbents used in wastewater treatment. In this work, the use of different vegetable wastes from agricultural or industrial processes has been evaluated as sorbents for metal removal from aqueous solutions. The aim of this work was to study first, the usefulness of olive stones as a sorbent for divalent metals such as Cd(II), Cu(II), Ni(II) and Pb(II) from aqueous solutions and then the use of four vegetable wastes (yohimbe bark, grape stalks, cork and olive stones) for the removal of Cr(VI) from aqueous solutions. The vegetable waste powder was encapsulated in calcium alginate to obtain spherical gel beads that were used in continuous flow process for Cr(VI) removal.
In all sorption experiments, kinetic data were modeled by the pseudo-second order kinetic equation and determine the constants sorption rates. Langmuir and Freundlich model isotherms were use to describe sorption equilibrium data and to obtain the isotherm parameters. In binary mixtures, the extended Langmuir isotherm model was used. The results showed that olive stones are a good sorbent for studied divalent metal. Metal uptake was pH dependent and the presence of salts in solution provokes a decrease in metal uptake. A clear competence between metals to be adsorbed on the waste was observed in metal binary mixtures. Although results obtained in Cr(VI) removal studies show that the four studied wastes can adsorb Cr(VI), grape stalks and yohimbe bark wastes showed the best chromium sorption capacity. X-Ray Photoelectron Spectroscopy analysis on grape stalks and yohimbe chromium loaded samples put into evidence that both Cr(VI) and Cr(III) were sorbed on wastes surface indicating that Cr(VI) sorption process involves a redox reaction.
The gel beads obtained when encapsulating grape stalks in calcium alginate showed a significant increase in Cr(VI) sorption capacity compared to the original grape stalks waste. A diffusion model was used to analyze the experimental data and to determine the diffusion coefficient for Cr(VI) sorption by beads containing different percentage of grape stalks encapsulated in calcium alginate.
Finally, preliminary studies of Cr(VI) removal in continuous flow using the beads containing grape stalks powder gel in laboratory columns have been carried out. The effect of operating parameters such as feed metal concentration, flow rate and bed depth was studied. The mass transfer and diffusion model used to describe column data showed the effect of feed metal concentration and flow rate in both, diffusion and mass transfer coefficients, respectively. The bed depth service time model (BDST) failed in predicting the service time when changing operating parameters due to the complexity of the sorption process. With these preliminary column experiments we established the basis for Cr(VI) sorption by the proposed sorbent in continuous flow process for further development of the process to be used in higher scale columns.

Il periodo tra la fine del III e l'inizio del II millennio a.C. in Alta Mesopotamia rappresenta nella storia e nell'archeologia del Vicino Oriente Antico una 'Media Aetas', un'età oscura tra la fioritura delle culture urbane del Bronzo Antico a metà del III millennio a.C. e lo sviluppo degli stati amorrei del Bronzo Medio, alla fine del XIX sec. a.C. L'identificazione nella sequenza archeologica di Tell Barri, l'antica città di Kahat, dell'orizzonte ceramico coevo alla 'crisi urbana' che precede la diffusione della ceramica dipinta del Khabur, associata ad un nuovo fenomeno di sedentarizzazione, permette di ridefinire la cronologia degli eventi nella regione, e di delineare i processi di interazione tra le diverse realtà sociali alto mesopotamiche in quella fase formativa che sta alla base del successivo sviluppo culturale di II millennio a.C.

碩士
國立臺南藝術大學
應用藝術研究所
95
Starting from the issue of “monster”, the text inquires into monster recorded on related ancient books. From literal meaning to the pictures of monster in history, the text goes further into defining what the creators called “monster”. The text sums up the development of monster’s style, compares with the growth process and observation on life of creators, combines various association of thoughts, and converted it into the context of each work and apply it to daily household utensils. At last, the text discusses the research and the craft skills of creation and interpreter the shaping points of each part one by one by diagram examples which can be used as reference for afterward creators.

Terahertz range of frequency has found a fast growing number of applications in material characterization and sensing, imaging and extreme bandwidth communication. Different structures have been proposed for sensing at these frequencies. Surface plasmon waves have successfully been applied to ultra-high precision sensing at optical frequencies, because of their strong field confinement and enhancement. These waves are not as confined in THz due to metal properties over this range of frequencies. However, it has been shown that surface waves on properly designed periodic metallic structure have behavior very similar to plasmonic waves in optical range. These surface wave modes are called surface plasmon-like waves. Here we consider several periodic metallic structures, which support these surface plasmon-like modes, for THz sensing applications. The first one is a two dimensional array of metallic rods which is excited by prism. Many existing plasmonic sensing configurations use prism for plasmonic wave excitation. However, prism is too bulky for integration. Interests in integrated surface plasmonic devices at optical frequencies have been growing recently. As compared with free space configuration, integrated structures have distinct advantages such as small size and multi-channel sensing capabilities. An integrated sensing configuration using plasmonic-like wave is proposed. The new configuration uses a metallic grating that acts as a THz waveguide with a stop-band with a sharp transition edge. Excitation of such metallic grating waveguide through a dielectric waveguide will be described and analyzed. Moreover, it will be shown that the frequency of the transition edge between pass-band and stop-band is highly sensitive to the refractive index of the surrounding medium, and therefore it can be used for dielectric sensing. The excitation requirements of the proposed sensor and its sensitivity will be presented.

by Leung, Kwok Kong.
Thesis (M.Phil.)--Chinese University of Hong Kong, 1999.
Includes bibliographical references (leaves 67).
Text in English; abstracts in English and Chinese.
by Leung, Kwok Kong.
Abstract --- p.ii
Acknowledgement --- p.iii
Contents --- p.iv
List of Figures --- p.vi
Chapter Chapter 1. --- Introduction --- p.1
Chapter Chapter 2. --- Transmittance in Metal-Dielectric Multilayers --- p.4
Chapter 2.1 --- Introduction --- p.4
Chapter 2.2 --- Transfer matrix approach --- p.5
Chapter 2.3 --- Transfer matrix simulation --- p.7
Chapter 2.4 --- Physical explanation --- p.14
Chapter Chapter 3. --- Optical Nonlinear Response of Composite Layer --- p.17
Chapter 3.1 --- Transfer matrix formalism for oblique incidence --- p.18
Chapter 3.1.1 --- Transfer matrix method in nonlinear region --- p.18
Chapter 3.1.2 --- S-polarization --- p.19
Chapter 3.1.3 --- P-polarization --- p.19
Chapter 3.1.4 --- Backward propagation technique --- p.22
Chapter 3.2 --- Nonlinear phase shift --- p.22
Chapter 3.3 --- Transfer matrix method approach --- p.24
Chapter 3.4 --- Analytic solution formalism --- p.26
Chapter Chapter 4. --- Study of Photonic Band Gap of Nonlinear Dielectrics --- p.33
Chapter 4.1 --- Introduction --- p.33
Chapter 4.2 --- Nonlinear response of single thin nonlinear layer --- p.34
Chapter 4.3 --- Nonlinear response of δ-function between two linear dielectric --- p.37
Chapter 4.4 --- Photonic band structure --- p.41
Chapter 4.4.1 --- Photonic band structure of linear thin films --- p.41
Chapter 4.4.2 --- Photonic band structure of linear layers --- p.42
Chapter 4.5 --- Photonic band gap of nonlinear dielectric multilayers --- p.46
Chapter Chapter 5. --- Optical Limiting of Composite Material --- p.49
Chapter 5.1 --- Transmittance of periodic multilayer structures --- p.50
Chapter 5.1.1 --- Transmittance properties at low intensity --- p.50
Chapter 5.1.2 --- Transmittance at high intensity: optical limiting effect --- p.52
Chapter 5.2 --- The effect of layer thickness on optical limiting --- p.53
Chapter 5.3 --- Optical limiting property of PBG materials --- p.55
Chapter Chapter 6. --- Conclusion --- p.63
Chapter Appendix A. --- Effective dielectric function --- p.64
Bibliography --- p.67

Aerospace structures comprising of metals and composites are exposed to extreme loading and environmental conditions which necessitates regular inspection and maintenance to verify and monitor overall structural integrity. The timely and accurate detection, characterization and monitoring of structural cracking, corrosion, delaminating, material degradation and other types of damage are of major concern in the operational environment. Along with these, stringent requirements of safety and operational reliability have lead to evolutionary methods for evaluation of structural integrity. As a result, conventional nondestructive evaluation methods have moved towards a new concept, Structural Health Monitoring (SHM). SHM provides in-situ information a bout the occurrence of damage if any, location and severity of damage and residual life of the structure and also helps in improving the safety, reliability and confidence levels of critical engineering structures. While the concepts underlying SHM are well understood, development of methods is still in a nascent stage which requires extensive research that is challenging and has been the main motivating factor for undertaking the work reported in the thesis. Under the scope of the investigations carried out in this thesis, an integrated approach using Ultrasonic (active) and Acoustic Emission (passive) methods has been explored for SHM of metallic and composite plate structures using a distributed array of surface bonded circular piezoelectric wafer active sensors(PWAS). In ultrasonic method, PWAS is used for actuation and reception of Lamb waves in plate structures. The damage detection is based on the interaction of waves with defects resulting in reflection, mode conversion and scattering. In acoustic emission (AE) technique, the same sensor is used to pick up the stress waves generated by initiation or growth of defects or damage. Thus, both the active and passive damage detection methods are used in this work for detection, location and characterization of defects and damage in metallic and composite plates with complex geometries and structural discontinuities. And, thus the strategy adopted is to use time-frequency analysis and time reversal technique to extract the information from Lamb wave signals for damage detection and a geodesic based Lamb wave approach for location of the damage in the structure. To start with experiments were conducted on aluminum plates to study the interaction of Lamb waves with cracks oriented at different angles and on a titanium turbine blade of complex geometry with a fine surface crack. Further, the interaction of Lamb wave modes with multiple layer delaminations in glass fiber epoxy composite laminates was studied. The data acquired from these experiments yielded complex sets of signals which were not easily discern able for obtaining the information required regarding the defects and damage. So, to obtain a basic understanding of the wave patterns, Spectral finite element method has been employed for simulation of wave propagation in composite beams with damages like delamination and material degradation. Following this, time-frequency analysis of a number of simulated and experimental signals due to elastic wave scattering from defects and damage were performed using wavelet transform (WT) and Hilbert-Huang transform(HHT).And, a comparison of their performances in the context of quantifying the damages has given detailed insight into the problem of identifying localized damages, dispersion of multi-frequency non-stationary signals after their interaction with different types of defects and damage, finally leading to quantification. Conventional Lamb wave based damage detection methods look for the presence of defects and damage in a structure by comparing the signal obtained with the baseline signal acquired under healthy conditions. The environmental conditions like change in temperature can alter the Lamb wave signals and when compared with baseline signals may lead to false damage prediction. So, in order to make Lamb wave based damage detection baseline free, in the present work, the time reversal technique has been utilized. And, experiments were conducted on metallic and composite plates to study the time reversal behavior ofA0 andS0Lamb wave modes. Damage in the form of a notch was introduced in an aluminum plate to study the changes in the characteristics of the time reversed Lamb wave modes experimentally. This experimental study showed that there is no change in the shape of the time reversed Lamb wave in the presence of defect implying no breakage of time reversibility. Time reversal experiments were further carried out on a carbon/epoxy composite T-pull specimen representing a typical structure. And, the specimen was subjected to a tensile loading in a Universal testing machine. PWAS sensor measurements were carried out at no load as also during different stages of delamination due to tensile loading. Application of time reversed A 0 and S0 modes for both healthy and delaminated specimens and studying the change in shape of the time reversed Lamb wave signals has resulted in successful detection of the presence of delamination. The aim of this study has been to show the effectiveness of Lamb wave time reversal technique for damage detection in health monitoring applications. The next step in SHM is to identify the damage location after the confirmation of presence of damage in the structure. Wave based acoustic damage detection methods (UT and AE) employing triangulation technique are not suitable for locating damage in a structure which has complicated geometry and contains structural discontinuities. And, the problem further gets compounded if the material of the structure is anisotropic warranting complex analytical velocity models. In this work, a novel geodesic approach using Lamb waves is proposed to locate the AE source/damage in plate like structures. The approach is based on the fact that the wave takes minimum energy path to travel from the source to any other point in the connected domain. The geodesics are computed numerically on the meshed surface of the structure using Dijkstra’s algorithm. By propagating the waves in reverse virtually from these sensors along the geodesic path and by locating the first inter section point of these waves, one can get the AE source/damage location. Experiments have been conducted on metallic and composite plate specimens of simple and complex geometry to validate this approach. And, the results obtained using this approach has demonstrated the advantages for a practicable source location solution with arbitrary surfaces containing finite discontinuities. The drawback of Dijkstra’s algorithm is that the geodesics are allowed to travel along the edges of the triangular mesh and not inside them. To overcome this limitation, the simpler Dijkstra’s algorithm has been replaced by a Fast Marching Method (FMM) which allows geodesic path to travel inside the triangular domain. The results obtained using FMM showed that one can accurately compute the geodesic path taken by the elastic waves in composite plates from the AE source/damage to the sensor array, thus obtaining a more accurate damage location. Finally, a new triangulation technique based on geodesic concept is proposed to locate damage in metallic and composite plates. The performances of triangulaton technique are then compared with the geodesic approach in terms of damage location results and their suitability to health monitoring applications is studied.