Mechanical fatigue is a failure phenomenon that occurs due to repeated application of mechanical loads. Very High Cycle Fatigue (VHCF) is considered as the domain of fatigue life greater than 10 million load cycles. Increasing numbers of structural components have service life in the VHCF regime, for instance in automotive and high speed train transportation, gas turbine disks, and components of paper production machinery. Safe and reliable operation of these components depends on the knowledge of their VHCF properties. In this thesis both experimental tools and theoretical modelling were utilized to develop better understanding of the VHCF phenomena. In the experimental part, ultrasonic fatigue testing at 20 kHz of cold rolled and hot rolled stainless steel grades was conducted and fatigue strengths in the VHCF regime were obtained. The mechanisms for fatigue crack initiation and short crack growth were investigated using electron microscopes. For the cold rolled stainless steels crack initiation and early growth occurred through the formation of the Fine Granular Area (FGA) observed on the fracture surface and in TEM observations of cross-sections. The crack growth in the FGA seems to control more than 90% of the total fatigue life. For the hot rolled duplex stainless steels fatigue crack initiation occurred due to accumulation of plastic fatigue damage at the external surface, and early crack growth proceeded through a crystallographic growth mechanism. Theoretical modelling of complex cracks involving kinks and branches in an elastic half-plane under static loading was carried out by using the Distributed Dislocation Dipole Technique (DDDT). The technique was implemented for 2D crack problems. Both fully open and partially closed crack cases were analyzed. The main aim of the development of the DDDT was to compute the stress intensity factors. Accuracy of 2% in the computations was attainable compared to the solutions obtained by the Finite Element Method. / Very High Cycle Fatigue (VHCF) is considered as the domain of fatigue life greater than 10 million load cycles. Structural components that have service life in the VHCF regime include wheels and axles of high speed trains, gas turbine disks, and components of paper production machinery. Safe and reliable design, and the longevity, of these components depends on the knowledge of their VHCF properties. The overall aim of the experimental portion of this thesis was to gain in-depth knowledge of the VHCF properties of stainless steels. Fatigue test data in the VHCF regime was generated for different stainless steel grades using ultrasonic fatigue testing. The mechanisms for fatigue crack initiation and short crack growth were investigated using electron microscopes. Theoretical modelling of complex crack geometries involving kinks and branches was carried out by using the Distributed Dislocation Dipole Technique (DDDT). The main aim of this development was to compute the stress intensity factors and to analyse the stress state around the cracks. The results showed that accuracy of 2% was attainable compared to the solutions obtained by Finite Element Method (FEM). / <p>Artikel 4 publicerad i avhandlingen som manuskript</p>

Diversas metodologias foram desenvolvidas nas últimas décadas para cálculo de propriedades que representassem quantitativamente a distribuição de carga eletrônica de forma mais simplista. A mais básica destas propriedades é chamada de carga atômica. Contudo, não havendo unanimidade quanto à utilização de um formalismo de cálculo de carga para situações abrangentes de estudo, há a necessidade de trabalhos voltados para uma análise comparativa entre as respostas destes formalismos em termos de carga atômica e parâmetros derivados. Assim, fez-se nesta dissertação uma investigação sobre valores de carga atômica e propriedades dinâmicas relacionadas, com importância em estudos sobre movimentos vibracionais em moléculas, como fluxo de carga e fluxo de dipolo, obtidos com os formalismos de cálculo de carga de Mulliken, NPA, CHELPG e QTAIM. Neste trabalho também se avaliou o efeito da escolha do método de cálculo, como Hartree-Fock e métodos que incluem correlação eletrônica (MP2, MP4(SDQ) e CCSD), e do conjunto de funções de base, através de funções como cc-pVDZ, cc-pVTZ e cc-pVQZ, sobre estas propriedades dinâmicas. Os sistemas analisados incluíram moléculas diatômicas e triatômicas lineares (HF, HCl, LiH, NaH, NaCl, LiF, NaF, LiCl, BF, AlF, BeO, MgO, CO, ClF, CO2, CS2, OCS, HCN e HNC) formadas por ligações de caráter variado, desde altamente iônicas até covalentes e incluindo ligações múltiplas. Também foram estudadas moléculas de clorofluorometanos (CH4, CH3Cl, CH3F, CH2Cl2, CH2F2, CH2ClF, CHCl3, CHF3, CHCl2F, CHClF2, CCl2F2, CClF3, CFCl3, CCl4, e CF4) para observação do efeito da troca de substituintes nas propriedades citadas. Pelos resultados obtidos, pode-se afirmar que apenas os formalismos NPA e QTAIM apresentam bom comportamento quanto à convergência em relação ao método de cálculo e/ou tamanho do conjunto de funções de base utilizados no estudo do fluxo de carga. Entretanto, apenas os valores QTAIM são consistentes com certas considerações químicas fundamentais, como fluxos de carga tendendo a zero durante o estiramento de ligações de predominante caráter iônico, em moléculas com estruturas próximas à geometria de equilíbrio. As cargas e seus fluxos obtidos com Mulliken apresentaram alta dependência e problemas de convergência com a escolha da função de base, além de valores incoerentes em alguns sistemas. Por sua vez, CHELPG não se mostrou adequado à aplicação da aproximação finita de dois pontos na obtenção dos valores numéricos de fluxos de carga. A análise da resposta destas propriedades à troca de substituintes em moléculas de clorofluorometanos seguiu destacando positivamente QTAIM em relação aos outros formalismos. Enquanto CHELPG demonstrou oscilações inconsistentes em gráficos destes valores em função do número de átomos de cloro e/ou flúor, NPA e Mulliken se mostraram sensíveis à troca de substituintes, entretanto, os valores de fluxo de carga observados em alguns casos estão em desacordo com a tendência esperada na troca de átomos de hidrogênio por átomos de cloro ou flúor. / Several methodologies were developed in the last few decades in order to obtain a property which could represent quantitatively electronic charge distributions in a simple way. The fundamental quantity in this treatment is called atomic charge. However, as long as there is not an agreement about the most indicated method to determine atomic charges for general systems or responses under study, it is necessary to analyze, comparatively, how these methods behave in given situations and how the values derived from them respond in each case. Hence, an investigation including charges and related quantities as charge flux and atomic dipole flux, which are of interest to vibrational analysis, was done by means of values resulting from four formalisms, that are, Mulliken, NPA, CHELPG and QTAIM. In this study were also evaluated the changes in such dynamic properties when the calculations are done by means of different methods, as Hartree-Fock and methods that include electron correlation (MP2, MP4(SDQ) and CCSD) and, with different basis sets as cc-pVDZ, cc-pVTZ and cc-pVQZ. The systems analyzed were diatomic and linear triatomic molecules (HF, HCl, LiH, NaH, NaCl, LiF, NaF, LiCl, BF, AlF, BeO, MgO, CO, FCl, CO2, CS2, OCS, HCN and HNC) including diverse bonding character, such as highly ionic or covalent bonds along with multiple bonds. Also, charge and charge flux parameters in chlorofluoromethane molecules (CH4, CH3Cl, CH3F, CH2Cl2, CH2F2, CH2ClF, CHCl3, CHF3, CHCl2F, CHClF2, CCl2F2, CClF3, CFCl3, CCl4 and CF4) were studied to analyze the effects in these properties during the exchange of substituent atoms. Considering the data obtained, one can infer that only NPA and QTAIM formalisms result in satisfactory convergence patterns with chosen methods and/or basis set sizes during the determination of charge and charge flux values. However, only QTAIM charge fluxes seem to follow certain chemical considerations, as low values for charge flux in a bond enlargement in systems with a predominant ionic character close to their equilibrium geometry. The Mulliken formalism shows high dependence and convergence issues in basis set size increments, as well as some inconsistent values. On other hand, CHELPG formalism is not suited to the finite approach for numerical derivatives in its two-point version. The study of substituent effects in chlorofluoromethanes reinforces the performance of QTAIM when compared to other formalisms. While CHELPG returned inconsistent oscillations in plots against the number of chlorine/fluorine atoms, NPA and Mulliken exhibited some sensibility with the change of substituent, though the flux values observed in a few cases are in disagreement with the tendencies expected when the hydrogen atoms are switched by chlorine or fluorine atoms.

<p>Controlling the surface chemistry of 2D materials is critical for the development of next generation applications including nanoelectronics and organic photovoltaics (OPVs). Further, next generation nanoelectronics devices require very specific 2D patterns of conductors and insulators with prescribed connectivity and repeating patterns less than 10 nm. However, both top-down and bottom-up approaches currently used lack the ability to pattern materials with sub 10-nm precision over large scales. Nevertheless, a class of monolayer chemistry offers a way to solve this problem through controlled long-range ordering with superior sub-10 nm patterning resolution. Graphene is most often functionalized noncovalently, which preserves most of its intrinsic properties (<i>i.e.,</i> electronic conductivity) and allows spatial modulation of the surface. Phospholipids such as 1,2-bis(10,12-tricsadiynoyl)-<i>sn­</i>-glycero-3-phosphoethanolamine (diyne PE) form lying down lamellar phases on graphene where both the hydrophilic head and hydrophobic tail are exposed to the interface and resemble a repeating cross section of the cell membrane. Phospholipid is made up of a complex headgroup structure and strong headgroup dipole which allows for a diverse range of chemistry and docking of objects to occur at the nonpolar membrane, these principals are equally as important at the nonpolar interface of 2D materials. A key component in the development of nanoelectronics is the integration of inorganic nanocrystals such as nanowires into materials at the wafer scale. Nanocrystals can be integrated into materials through templated growth on to surface of interest as well as through assembly processes (i.e. interfacial adsorption). </p> <p>In this work, I have demonstrated that gold nanowires (AuNWs) can be templated on striped phospholipid monolayers, which have an orientable headgroup dipoles that can order and straighten flexible 2-nm diameter AuNWs with wire lengths of ~1 µm. While AuNWs in solution experience bundling effects due to depletion attraction interactions, wires adsorb to the surface in a well separated fashion with wire-wire distances (e.g. 14 or 21 nm) matching multiples of the PE template pitch. This suggests repulsive interactions between wires upon interaction with dipole arrays on the surface. Although the reaction and templating of AuNWs is completed in a nonpolar environment (cyclohexane), the ordering of wires varies based on the hydration of the PE template in the presence of excess oleylamine, which forms hemicylindrical micelles around the hydrated headgroups protecting the polar environment. Results suggest that PE template experience membrane-mimetic dipole orientation behaviors, which in turn influences the orientation and ordering of objects in a nonpolar environment.</p> <p>Another promising material for bottom-up device applications is MoS₂substrates due to their useful electronic properties. However, being able to control the surface chemistry of different materials, like MoS₂, is relatively understudied, resulting in very limited examples of MoS₂substrates used in bottom-up approaches for nanoelectronics devices. Diyne PE templates adsorb on to MoS₂­in an edge-on conformation in which the alkyl tails stack on top of each other increasing the overall stability of the monolayer. A decrease in lateral spacing results in high local concentrations of orientable headgroups dipoles along with stacked tails which could affect the interactions and adsorption of inorganic materials (i.e. AuNW) at the interface. </p> <p>Here, I show that both diyne PE/HOPG and diyne PE/MoS₂ substrates can template AuNW of various lengths with long range ordering over areas up to 100 µm². Wires on both substrates experience repulsive interactions upon contact with the headgroup dipole arrays resulting in wire-wire distances greater than the template pitch (7 nm). As the wire length is shortened the measured distance between wires become smaller eventually resulting in tight packed ribbon phases. Wires within these ribbon phases have wire-wire distances equal to the template. Ribbon phases occur on diyne PE/HOPG substrates when the wire length is ~50 nm, whereas wire below ~600 nm produce ribbon phases on diyne PE/MoS_2­substrates. </p> <p>Another important aspect to future scientific development is the catalysis of organic reactions, specifically oxygenation of organic sulfides. Sulfide oxygenation is important for applications such as medicinal chemistry, petroleum desulfurization, and nerve agent detoxification. Both reaction rates and the use of inexpensive oxidants and catalysts are important for practical applications. Hydrogen peroxide and <i>tert</i>-butyl hydroperoxide are ideal oxidants due to being cost efficient and environmentally friendly. Hydrogen peroxide can be activated through transition metal base homogeneous catalysts. Some of the most common catalysts are homo- and hetero-polyoxometalates (POMs) due their chemical robustness. Heptamolybdate [Mo₇O₂₄]^6-is a member of the isopolymolybdate family and its ammonium salt is commercially available and low in cost.²² Heteropolyoxometalates have been widely studied as a catalyst for oxygenation reactions whereas heptamolybdate has been rarely studied in oxygenation reactions. </p> <p> Here I report sulfide oxygenation activity of both heptamolybdate and its peroxo derivate [Mo₇O₂₂(O₂)₂]^6-. Sulfide oxygenation of methyl phenyl sulfide (MPS) by H₂O₂to sulfoxide and sulfone occurs rapidly with 100 % utility of H₂O₂ in the presence of [Mo₇O₂₂(O₂)₂]^6-, suggesting the peroxo adduct is an efficient catalyst. However, heptamolybdate is a faster catalyst compared to [Mo₇O₂₂(O₂)₂]^6- for MPS oxygenation and all other sulfides tested under identical conditions. Pseudo-first order <i>k</i>_cat constants from initial rate kinetics show that [Mo₇O₂₄]^6-catalyzes sulfide oxygenation faster. The significant difference in the <i>k</i>_cat suggests differences in the active catalytic species, which was characterized by both UV-Vis and electrospray ionization mass spectrometry. ESI-MS suggest that the active intermediate of [Mo₇O₂₄]^6-under catalytic reaction conditions for sulfide oxygenation by H₂O₂ is [Mo₂O₁₁]^2-. These results show that heptamolybdate is a highly efficient catalyst for H₂O₂oxygenation of organic sulfides.</p>

This project is focused on computer modeling of so-called meta-materials, and on the exploitation of metamaterials in the design of electrically small antennas. For modeling, COMSOL Multiphysics 3.3 was used. Simulations were focused on impedance matching of antennas. Antennas with metamaterials were compared with corresponding conventional antennas without metamaterial layers. The project does not investigate the creation of metamaterials; the project concentrates on their influence on crucial parameters of antennas. Next step this project is focused on optimalization this structure in program Matlab version R2009b. We used optimalization method PSO (swarms of particles) and results are comparing whit results calculating in COMSOL program.

V disertační práci popisuji metodu syntézy dipólové anténní řady s definovanou schopností prostorové a spektrální filtrace. Díky prostorové filtraci se směr hlavního laloku a hodnota zisku mění v celém pracovním pásmu jen zanedbatelně. Díky spektrální filtraci je hodnota zisku v pracovním pásmu nejvyšší a mimo toto pásmo nejnižší. Abychom syntetizovali anténní řadu s předepsanými filtračními vlastnostmi, optimalizujeme amplitudy, fáze a rozměry prvků dipólové anténní řady. Abychom počáteční optimalizaci co nejvíce urychlili, předpokládáme při výpočtu hodnot kriteriálních funkcí idealizovanou anténní řadu. Jelikož optimalizace zahrnuje požadavky na směr hlavního laloku, zisk i impedanční přizpůsobení, využíváme k syntéze multi-kriteriální optimalizaci. Optimalizovaná anténní řada byla následně analyzována ve vlnovém simulátoru, aby byl ověřen výsledek syntézy. Syntetizovaná anténní řada byla vyrobena a experimentálně byly ověřeny její vlastnosti.

This work deals with the study of Yagi-Uda antennas, followed by analysis and design of planar antenna with wired reflector. The first part focused on the analysis of the antenna and parameters. Another part of the continuing investigation of the optimum parameters for a given antenna followed by a design in Wi-Fi 5 GHz band. The antenna is simulated in CST Microwave Studio. The final part devoted the results achieved

A new hypothesis of matter formation after the big bang based on either particle-wave duality or electric dipole asymmetry. Both assumptions allow to postulate that the probability of matter formation is slightly higher than that of antimatter formation. As a consequence, this difference of probabilities ∆Pp for protons and ∆Pe with regard to electrons avoided complete annihilation in the beginning.

Some experiments have indicated the possible existence of par ticles with a negative inertial mass. It is shown under which condit ions Weber’s electrodynamics gives rise to this effect. Some specific experiments related to this aspect of Weber’s law are described. Two particles equ ally electrified with charges of the same sign would then move toward one an other if they had negative effective inertial masses. A new concept for nuclear fusion is presented based on the possibility of creating a negative effective inertial mass for ions. It is then considered some properties of the inertial dipole, that is, a system composed by a pair of particles in which one particle has a positive effective inertial mass while the other particle has a negative effective inertial mass. The possible utilization of the inertialdipole as a propulsion system is briefly discussed.

This thesis deals with the development of new reaction methodology as well as stereochemical investigations. The first part concerns the investigation of 1,2- and merged 1,2- and 1,3- asymmetric induction in Mukaiyama aldol additions to α-heteroatom and α,β- heteroatom substituted aldehydes respectively. In particular, the unexpected 1,2-syn selectivity obtained in the addition of sterically hindered nucleophiles to α-chloroaldehydes is examined, and an explanation for the observed stereochemical trends is proposed. The second part describes the development of a novel entry to α-amino-β- hydroxy esters by a 1,3-dipolar cycloaddition reaction of aldehydes and azomethine ylides, generated by thermolysis of aziridines. The third part deals with our efforts to develop a novel entry to vicinal all- carbon quaternary centers, based on an intramolecular domino Heck- carbonylation reaction using tetrasubstituted olefins. / QC 20120611

From the point of view of the electromagnetic interaction, empirical descriptions of the nucleus involve only a few parameters, one of the most important being the nuclear charge radius. This has been well measured for ground state nuclei, but it is difficult to measure for excited states, since they decay too quickly for conventional methods to be used. We study the atomic transitions in muonic ^{90}Zr and find that the nuclear charge radius of the first excited state can be inferred by measuring the gamma emissions from certain transitions. We find that with 1keV photon resolution, we can infer a difference between the charge radius of the nuclear ground state and first excited state as small as 0.13%. We will work in units where h = c = 4\pi\epsilon_0 = 1 so that e^2 = \alpha \approx 1/137 (unless otherwise specified). Mass, momentum, and energy will have units of eV, whereas distances will be given in eV^{-1}. In qualitative discussion, we will sometimes revert to discussing distances in meters due to the familiarity of typical scales (e.g. nuclear radius, Bohr radius). When working with 4-vectors in Minkowski space, we use the metric convention (+,-,-,-). / Graduate