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ABSTRACTNeutron hardening and embrittlement of pressure vessel steels is due to a high density of nanometer scale features, including Cu-rich precipitates which form as a result of radiation enhanced diffusion. High-energy displacement cascades generate large numbers of both isolated point defects and clusters of vacancies and interstitials. The subsequent clustering, diffusion and ultimate annihilation of primary damage is inherently coupled with solute transport and hence, the overall chemical and microstructural evolutions under irradiation. In this work, we present atomistic simulation results, based on many-body interatomic potentials, of the migration of vacancies, solute and self-interstitial atoms (SIA) in pure Fe and binary Fe-0.9 and 1.0 at.% Cu alloys. Cu diffusion occurs by a vacancy mechanism and the calculated Cu diffusivity is in good agreement with experimental data. Strain field interactions between the oversized substitutional Cu solute atoms and SIA and SIA clusters are predominantly repulsive and result in both a decreased activation energy and diffusion pre-factor for SIA and small (N <5) SIA cluster migration, which occurs by three-dimensional motion. The Cu appears to enhance the re- orientation of the SIA clusters to different <111> directions, as well as the transition from <110> to mobile <111> configurations. The migration behavior of larger SIA clusters, which undergo only one-dimensional diffusion during molecular dynamics timescales, is largely unaffected by the Fe-Cu alloy, although SIA clusters are effectively repelled by coherent Cu precipitates.

Abstract We have added expanded vermiculite and polypropylene fibers with low thermal conductivity to lightweight gypsum. Thermal conductivity of the composites decreases on addition of vermiculite as pore-maker. Physical and mechanical properties of the composites are improved by incorporating polypropylene fibers. A nonlinear finite element model of a three point bending model and a design of experiments analysis have been developed to evaluate and optimize the additive concentrations and also to understand the effects provided by the additives on the mechanical strength. Statistical response surface method with three-level factorial was employed to evaluate the effect of addition of vermiculite and polypropylene fibers on gypsum composites. Our methodology can be applied to other nonlinear materials for property optimization.

ABSTRACTA detailed chemical kinetic model for oxidation of CH3OH at high pressure and intermediate temperatures has been developed and validated experimentally. Ab initio calculations and Rice–Ramsperger–Kassel–Marcus/transition state theory (RRKM/TST) analysis were used to obtain rate coefficients for , , , and . The experiments, involving CH3OH/O2 mixtures diluted in N2, were carried out in a high‐pressure flow reactor at 600–900 K and 20–100 bar, varying the reaction stoichiometry from very lean to fuel‐rich conditions. Under the conditions studied, the onset temperature for methanol oxidation was not dependent on the stoichiometry, whereas increasing pressure shifted the ignition temperature toward lower values. Model predictions of the present experimental results, as well as rapid compression machine data from the literature, were generally satisfactory. The governing reaction pathways have been outlined based on calculations with the kinetic model. Unlike what has been observed for unsaturated hydrocarbons, the oxidation pathways for CH3OH under the investigated conditions were very similar to those prevailing at higher temperatures and lower pressures. At the high pressures, the modeling predictions for onset of reaction were particularly sensitive to the reaction.

Coupling of Rayleigh waves propagating along two metal surfaces separated by a narrow fluid channel is predicted and experimentally observed. Although the coupling through a fluid (water) is weak, a strong synchronization in propagation of Rayleigh waves even for the metals with sufficiently high elastic contrast (brass and aluminum) is observed. Dispersion equation for two polarizations of the coupled Rayleigh waves is derived and experimentally confirmed. Excitation of coupled Rayleigh waves in a channel of finite length leads to anomalously low transmission of acoustic energy at discrete set of resonant frequencies. This effect may find useful applications in the design of acoustic metamaterial screens and reflectors.

QCD es una teoría que gobierna la interacción fuerte entre quarks y gluones dentro de los hadrones, por ejemplo, protones y neutrones. Esta teoría tiene dos características: libertad asintótica y color confinamiento. La dependencia de la constante de acoplamiento con la escala es tal que esta decrece con la distancia entre partones. Esto permite realizar precisos cálculos teóricos a una gran escala de energía usando teoría de perturbaciones (pQCD). Además, la fuerza de la interacción incrementa con la distancia entre partones y gluones obligando que estos estén confinados en hadrones. En el acelerador Tevatron, protones y antiprotones colisionan a una alta energía. En estas colisiones se producen jets de hadrones colimados en la misma dirección de los quarks y gluones que han colisionado. La medida de la sección eficaz de producción de jets centrales constituye una prueba de las predicciones de pQCD en más de ocho órdenes de magnitud. Además la medida también es sensible a la distribución de los partones dentro del proton (PDFs). Medidas de la producción de jets a grandes rapidititis son importantes porque ayudan a restringir la incertidumbre en esas distribuciones de los partones en una región donde no se espera señal de nueva física. Esta tesis presenta la medida de producción de jets usando datos recogidos por el experimento CDF, uno de los detectores que estudia las colisiones en Tevatron. La medida esta hecha con un algoritmo muy preciso para buscar jets, relativamente nuevo en colisionadores hadrónicos. La medida esta comparada con predicciones de pQCD, donde los efectos de efectos no-perturbativos han sido incluidos. Los resultados demuestran que hay un excelente acuerdo entre la medida y la teoría, no mostrando señal de nueva física. Además, las incertidumbre es la medida son mas pequeñas que la teoría, cosa que indica que estas medidas pueden ser usadas para restringir las PDFs. QCD is the gauge theory that governs the strong interactions between quarks and gluons inside hadrons like, for example, protons and neutrons. It shows two well established characteristics, related to the non-abelian nature of the theory, that dominate its phenomenology: asymptotic freedom and color confinement. The dependence of the strong coupling with the hard scale is such that it decreases with decreasing the distance between partons. This allows performing precise theoretical calculations at large energy transfer using perturbative QCD (pQCD). In the other hand, the strength of the interaction increases with the distance between partons and thus colored quarks and gluons are forced to be confined inside colorless hadrons. At the Tevatron at Fermilab, protons and antiprotons collide at very high energy. In those collisions, collimated jets of hadrons are produced along the direction of struck quarks and gluons in the final state. The measurement of the inclusive jet production cross section provides a stringent test of pQCD predictions over almost nine orders of magnitude. In addition, the measurement is sensitive to the parton distribution in the proton (PDFs). Jet measurements at large rapidities are important because they constrain the gluon density in a region where no effect from new physics is expected. This PhD. Thesis presents a measurement of the inclusive jet production cross section using the new data collected by the CDF experiment in Run II, one of the detectors at Tevatron. The longitudinally invariant kT algorithm has been used in order to search for jets in the final state. The measurement is compared to pQCD NLO calculations where non-perturbative effects from the underlying event and the fragmentation of partons into jets of hadrons have been taken into account. The results show an excellent agreement between the measurements and the theory, without presenting signal for new physics. In addition the systematic uncertainties in the measurements are smaller than in the theory, indicating that these measurements can be used to constrain the PDFs.

Capítulos en libros It is generally believed that plug-in electric vehicles (PEVs) offer environmental and energy security advantages compared to conventional vehicles. Policies are stimulating electric transportation deployment, and PEV adoption may grow significantly. New technology and business models are being developed to organize the PEV interface and their interaction with the wider grid. This paper analyzes the PEVs integration into a building s Energy Management System (EMS), differentiating between vehicle to macrogrid (V2M) and vehicle to microgrid (V2m) applications. This relationship is modeled by the Distributed Energy Resources Customer Adoption Model (DER-CAM), which finds optimal equipment combinations to meet microgrid requirements at minimum cost, carbon footprint, or other criteria. Results derive battery value to the building and the possibility of a contractual affiliation sharing the benefit. Under simple annual fixed payments and energy exchange agreements, vehicles are primarily used to avoid peak demand charges supplying cheaper off-peak electricity to the building during workdays. info:eu-repo/semantics/publishedVersion

El model estandar (ME) és actualment el marc teòric més complet que descriu la física de les partícules elementals. En ell s'hi descriuen les partícules de matèria (fermions) i les seves interaccions (bosons). Fins ara no s'ha trobat cap desviació significativa entre l'experiment i les prediccions del model. Així i tot, el ME no pot ser la teoria final que descriu la física de partícules perquè pateix dificultats teòriques importants a més altes energies. Una de les possibles extensions del ME amb més acceptació és la Supersimetria (SUSY) que relaciona masses i acoblaments entre bosons i fermions. D'aquesta forma, per cada bosó existent al ME ha d'existir una "super-parella" fermiònica i a l'inrevés. A més, una altra simetria anomenada "paritat R" s'hi acostuma a introduir per tal d'evitar la violació del nombre bariònic i leptònic. Si això és així, aquestes noves partícules, que apareixerien a l'escala energètica dels TeV, s'haurien de formar per parelles i no podrien desintegrar-se completament en partícules del ME. Això implica l'existència d'una partícula supersimètrica que sigui la més lleugera de totes (LSP), la qual serà estable i un candidat a explicar la presència de matèria fosca freda a l'univers.Precisament l'escala energètica dels TeV és el rang d'energies accessible per al col·lisionador protó-antiprotó Tevatron (Fermilab). Tevatron i els seus dos experiments, els detectors CDF i D0 van ser preparats per l'anomenat "Run II" en el que les col·lisions se succeeixen cada 396 ns amb un centre de masses d'1.96 TeV. Degut a què les noves partícules són molt massives, es desintegren en cascades amb múltiples raigs de partícules (jets) d'alt moment transversal. Quan la paritat R es conserva, dos LSP són produïts que escapen del detector deixant un important desequilibri en el balanç energètic del succés.Aquesta tesi tracta de la recerca de les super-parelles dels quarks (squarks) i gluons (gluinos) en múltiples jets i energia transversa mancant, amb les dades recollides amb el detector CDF durant gran part del Run II (371 pb-1 de lluminositat). Per aquest motiu, s'ha dut a terme un estudi curós de les condicions del feix i dels diferents processos del ME que tenen estats finals similars al senyal. Diferents talls per reduir la seva presència tot potenciant el possible senyal s'han estudiat i optimitzat. També s'han considerat les diferents fonts d'errors experimentals i teòrics per tal de fer una bona caracterització de les dades.Observant les dades, no s'ha trobat cap desviació significativa de les prediccions del ME. Degut a aquests resultats, s'han posat límits inferiors a la massa squarks i gluinos (menor de 387 GeV/c2) en un determinat escenari del model teòric anomenat mSUGRA. Aquest estudi és pioner al Run II de CDF i els resultats presenten millores significatives respecte a anteriors límits. En aquest sentit, el present treball constitueix la base i serà la referència per a futures extensions amb més dades.

AbstractSequential photoinduced energy transfer followed by electron transfer and the formation of charge‐separated states, which are primary events of natural photosynthesis, have been demonstrated in a newly synthesized multichromophoric covalently linked triad, PDI‐SiPc‐C60. The triad comprises a perylenediimide (PDI), which primarily fulfils antenna and electron‐acceptor functionalities, silicon phthalocyanine (SiPc) as an electron donor, and fulleropyrrolidine (C60) as a second electron acceptor. The multi‐step convergent synthetic procedure developed here produced good yields of the triad and control dyads, PDI‐SiPc and SiPc‐C60. The structures and geometries of the newly synthesized donor–acceptor systems have been established from spectral, computational, and electrochemical studies with reference to appropriate control compounds. Ultrafast energy transfer from 1PDI* to SiPc in the case of PDI‐SiPc and PDI‐SiPc‐C60 was witnessed. An energy‐level diagram established from spectral and electrochemical data suggested the formation of two types of charge‐separated states, that is, PDI‐SiPc.+‐C60.− and PDI.−‐SiPc.+‐C60 from the 1SiPc* in the triad, with generation of the latter being energetically more favorable. However, photochemical studies involving femtosecond transient spectroscopy revealed the formation of PDI‐SiPc.+‐C60.− as a major charge‐separated product. This observation may be rationalized in terms of the closer spatial proximity to SiPc of C60 compared to PDI in the triad. The charge‐separated state persisted for a few nanoseconds prior to populating the 3SiPc* state during charge recombination.