2,091 research outputs found

    Group V Mixing Effects in the Structural and Optical Properties of (ZnSi)1/2(P)1/4(As)1/4

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    We present {\it ab initio} total energy and band structure calculations based on Density Funtional Theory (DFT) within the Local Density Aproximation (LDA) on group-V mixing effects in the optoelectronic material (ZnSi)1/2P1/4As3/4(ZnSi)_{1/2}P_{1/4}As_{3/4}. This compound has been recently proposed by theoretical design as an optically active material in the 1.5 μ\mum (0.8 eV) fiber optics frequency window and with a monolithic integration with the Si (001) surface. Our results indicate that alloy formation in the group V planes would likely occur at typical growth conditions. In addition, desired features such as in-plane lattice constant and energy gap are virtually unchanged and the optical oscillator strength for band-to-band transitions is increased by a factor of 6 due to alloying

    A covariant constituent-quark formalism for mesons

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    Using the framework of the Covariant Spectator Theory (CST) [1] we are developing a covariant model formulated in Minkowski space to study mesonic structure and spectra. Treating mesons as effective qqˉq\bar{q} states, we focused in [2] on the nonrelativistic bound-state problem in momentum space with a linear confining potential. Although integrable, this kernel has singularities which are difficult to handle numerically. In [2] we reformulate it into a form in which all singularities are explicitely removed. The resulting equations are then easier to solve and yield accurate and stable solutions. In the present work, the same method is applied to the relativistic case, improving upon the results of the one-channel spectator equation (1CSE) given in [3].Comment: 6 pages, 5 figures, Presented at EEF70, Workshop on Unquenched Hadron Spectroscopy: Non-Perturbative Models and Methods of QCD vs. Experimen

    Correction to: Northerly wind trends along the Portuguese marine coast since 1950

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    All figure captions are not accurate. Also, there is a repeated error in most figures because the vertical scales incorrectly show Wind Strenght instead of Wind Strength and in Fig. 4 (mid-panel) 2003 instead of 2004.info:eu-repo/semantics/publishedVersio

    High resolution tsunami modelling for the evaluation of potential risk areas in Setúbal (Portugal)

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    The use of high resolution hydrodynamic modelling to simulate the potential effects of tsunami events can provide relevant information about the most probable inundation areas. Moreover, the consideration of complementary data such as the type of buildings, location of priority equipment, type of roads, enables mapping of the most vulnerable zones, computing of the expected damage on man-made structures, constrain of the definition of rescue areas and escape routes, adaptation of emergency plans and proper evaluation of the vulnerability associated with different areas and/or equipment. <br><br> Such an approach was used to evaluate the specific risks associated with a potential occurrence of a tsunami event in the region of Setúbal (Portugal), which was one of the areas most seriously affected by the 1755 tsunami. <br><br> In order to perform an evaluation of the hazard associated with the occurrence of a similar event, high resolution wave propagation simulations were performed considering different potential earthquake sources with different magnitudes. Based on these simulations, detailed inundation maps associated with the different events were produced. These results were combined with the available information on the vulnerability of the local infrastructures (building types, roads and streets characteristics, priority buildings) in order to impose restrictions in the production of high-scale potential damage maps, escape routes and emergency routes maps
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