372 research outputs found
A control problem arising in the process of waste water purification
AbstractIn this paper we state and solve an optimal control problem arisen from the management of the sewage disposal which is dumped into the sea through submarine outfalls. Firstly, we fix oxygen and amount of organic matter as water quality indicators and we state a partial differential equations model to simulate them in a domain occupied by shallow waters. Constraints about water quality and economic objectives lead us to a pointwise optimal control problem with state and control constraints. (The theoretical analysis of the problem has been developed by the authors in (Martinez et al., C. R. Acad. Sci. Paris, Serie I 328 (1999) 35.) (Martinez et al., Preprint, Dept. Matematica Aplicada, Univ. Santiago de Compostela, Spain, 1998.)). We deal with the problem by using time and space discretizations and we propose two algorithms for the numerical resolution of the discretized problem. Finally, we give numerical results obtained by applying the described techniques for a realistic problem posed in the rıÌa of Vigo (Spain)
Physical limitations of travel time based shallow water tomography
Travel-time-based tomography is a classical method for inverting sound-speed perturbations in an arbitrary environment. A linearization procedure enables relating travel-time perturbations to sound-speed perturbations through a kernel matrix. Thus travel-time-based tomography essentially
relies on the inversion of the kernel matrix and is commonly called âlinear inversion. In practice, its spatial resolution is limited by the number of resolved and independent arrivals, which is a basic linear algebra requirement for linear inversion performance. Physically, arrival independency is much more difficult to determine since it is closely related to the sound propagating channel characteristics. This paper presents a brief review of linear inversion and shows that, in deep water,
the number of resolved arrivals is equal to the number of independent arrivals, while in shallow water the number of independent arrivals can be much smaller than the number of resolved arrivals.
This implies that in shallow water there are physical limitations to the number of independent travel times. Furthermore, those limitations are explained through the analysis of an equivalent environment with a constant sound speed. The results of this paper are of central importance for the
understanding of travel-time-based shallow water tomography
Propagation mechanism modelling in the near region of circular tunnels
ArtĂculo sobre comunicaciones ferroviarias.
Abstract: Along with the increase in operating frequencies in advanced radio communication systems utilised inside tunnels, the location of the break point is further and further away from the transmitter. This means that the near region lengthens considerably and even occupies the whole propagation cell or the entire length of some short tunnels. To begin with, this study analyses the
propagation loss resulting from the free-space mechanism and the multi-mode waveguide mechanism in the near region of circular tunnels, respectively. Then, by conjunctive employing the propagation theory and the three-dimensional solid geometry, a general analytical model of the dividing point between two propagation mechanisms is presented for the first time. Moreover, the model is validated by a wide range of measurement campaigns in different tunnels at different frequencies. Finally, discussions on the
simplified formulae of the dividing point in some application situations are made. The results in this study can be helpful to grasp the essence of the propagation mechanism inside tunnels
Logistic regression for simulating damage occurrence on a fruit grading line
Many factors influence the incidence of mechanical damage in fruit handled on a grading line. This makes it difficult to address damage estimation from an analytical point of view. During fruit transfer from one element of a grading line to another, damage occurs as a combined effect of machinery roughness and the intrinsic susceptibility of fruit. This paper describes a method to estimate bruise probability by means of logistic regression, using data yielded by specific laboratory tests. Model accuracy was measured via the statistical significance of its parameters and its classification ability. The prediction model was then linked to a simulation model through which impacts and load levels, similar to those of real grading lines, could be generated. The simulation output sample size was determined to yield reliable estimations. The process makes it possible to derive a suitable line design and the type of fruit that should be handled to maintain bruise levels within European Union (EU) Standards. A real example with peaches was carried out with the aid of the software implementation SIMLINÂź, developed by the authors and registered by Madrid Technical University. This kind of tool has been demanded by inter-professional associations and grading lines designers in recent year
Supression of magnetic subbands in semiconductor superlattices driven by a laser field
The effect of strong laser radiation on magnetic subbands in semiconductor
superlattices is investigated. Due to the presence of a magnetic field
perpendicular to the growth direction, non-linear effects such as band
supression and electron localization become relevant at relatively lower
intensities and for any polarization perpendicular to the magnetic field.
Electron quasienergies and density of states are calculated in the
Kramers-Henneberger approximation, whose validity is discussed. The conditions
under which collapse of magnetic subbands and quenching of N-photon emission or
absorption processes occur are discussed. We conclude that at laser frequencies
close to cyclotronic frequency and intensities typical of c.w. lasers, magnetic
subbands become flat, magnetotunneling is inhibited and multiphotonic processes
dominate optical absorption.Comment: 4 pages RevTex, 2 figure
Curvature singularity of the distributional BTZ black hole geometry
For the non-rotating BTZ black hole, the distributional curvature tensor
field is found. It is shown to have singular parts proportional to a
-distribution with support at the origin. This singularity is related,
through Einstein field equations, to a point source. Coordinate invariance and
independence on the choice of differentiable structure of the results are
addressed.Comment: Latex, 7 page
Quantum superintegrability and exact solvability in N dimensions
A family of maximally superintegrable systems containing the Coulomb atom as
a special case is constructed in N-dimensional Euclidean space. Two different
sets of N commuting second order operators are found, overlapping in the
Hamiltonian alone. The system is separable in several coordinate systems and is
shown to be exactly solvable. It is solved in terms of classical orthogonal
polynomials. The Hamiltonian and N further operators are shown to lie in the
enveloping algebra of a hidden affine Lie algebra
Muon Track Reconstruction and Data Selection Techniques in AMANDA
The Antarctic Muon And Neutrino Detector Array (AMANDA) is a high-energy
neutrino telescope operating at the geographic South Pole. It is a lattice of
photo-multiplier tubes buried deep in the polar ice between 1500m and 2000m.
The primary goal of this detector is to discover astrophysical sources of high
energy neutrinos. A high-energy muon neutrino coming through the earth from the
Northern Hemisphere can be identified by the secondary muon moving upward
through the detector. The muon tracks are reconstructed with a maximum
likelihood method. It models the arrival times and amplitudes of Cherenkov
photons registered by the photo-multipliers. This paper describes the different
methods of reconstruction, which have been successfully implemented within
AMANDA. Strategies for optimizing the reconstruction performance and rejecting
background are presented. For a typical analysis procedure the direction of
tracks are reconstructed with about 2 degree accuracy.Comment: 40 pages, 16 Postscript figures, uses elsart.st
Responsiveness of pituitary to galanin throughout the reproductive cycle of male European sea bass (Dicentrarchus labrax)
The neuropeptide galanin (Gal) is a putative factor regulating puberty onset and reproduction through its actions on the pituitary. The present study investigated the pituitary responsiveness to galanin and the patterns of galanin receptors (Galrs) expression throughout the reproductive cycle of two years old male European sea bass (Dicentrarchus labrax), an important aquaculture species. Quantitative analysis of pituitary and hypothalamus transcript expression of four galr subtypes revealed differential regulation according to the testicular developmental stage, with an overall decrease in expression from the immature stage to the mid-recrudescence stage. Incubation of pituitary cells with mammalian 1-29 Gal peptide induced significant changes in cAMP concentration, with sensitivities that varied according to the testicular development stages. Furthermore 1-29 Gal was able to stimulate both follicle stimulating hormone (Fsh) and luteinizing hormone (Lh) release from pituitary cell suspensions. The magnitude of the effects and effective concentrations varied according to reproductive stage, with generalized induction of Fsh and Lh release in animals sampled in January (full spermiation). The differential expression of galrs in pituitary and hypothalamus across the reproductive season, together with the differential effects of Gal on gonadotropins release in vitro strongly suggests the involvement of the galaninergic system in the regulation the hypothalamus-pituitary-gonad axis of male sea bass. This is to our knowledge the first clear evidence for the involvement of galanin in the regulation of reproduction in non-mammalian vertebrates. (C) 2017 Elsevier Inc. All rights reserved.European Union Seventh Framework Programme [262336]Spanish Ministry of Science and Innovation (MICINN)Spanish Ministry of the Economy and Competitiveness (MINECO) [AGL2009-11086]Spanish Ministry of the Economy and CompetitivenessRegional Government of Valencia [PROME-TEOH/2014/051]info:eu-repo/semantics/acceptedVersio
Crystal structure of sinhalite MgAlBO4 under high pressure
This document is the Accepted Manuscript version of a Published Work that appeared in final form in
Journal of Physical Chemistry C, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://dx.doi.org/10.1021/jp512131eWe report on high-pressure angle-dispersive X-ray diffraction data up to 27 GPa for natural MgAlBO4 sinhalite mineral and ab initio total energy calculations. The experimental bulk modulus of sinhalite is B-0 = 171(3) GPa with a first-pressure derivative of B-0' = 4.2(3). A comparison with other olivine-type compounds shows that the value for B0 is 27% larger than that of Mg2SiO4 forsterite and 29% smaller than that of Al2BeO4 chrysoberyl. These differences are interpreted, on the basis of our ab initio calculations, in terms of the relative incompressibility of Al-O bonds in AlO6 octahedra (with a calculated bulk modulus of 250(1) GPa) as compared to Mg-O bonds in MgO6 octahedra (with a calculated bulk modulus of 130(1) GPa). The spatial cation distribution in the Pbnm orthorhombic unit cell and different polyhedral compressibilities entails a strong anisotropic compression comparable to that of forsterite. The axial compressibilities are 1.06(2) x 10(-3), 2.17(2) x 10(-3), and 1.30(3) x 10(-3) GPa(-1) for a, b, and c axes, respectively. The crystal chemistry of sinhalite under compression is compared to that of other olivine-like compounds. Compressibility trends and possible high-pressure phases are discussed.This study was supported by the Spanish government MEC under Grants No: MAT2010-21270-C04-01/03/04, MAT2013-46649-C4-1/2/3-P, and CTQ2009-14596-C02-01, by the Comunidad de Madrid and European Social Fund (S2009/PPQ1551 4161893), by MALTA Consolider Ingenio 2010 project (CSD2007-00045), and by Generalitat Valenciana (GVA-ACOMP-2013-1012 and GVA-ACOMP-2014-243). Experiments were performed at MSPD beamline at ALBA Synchrotron Light Facility with the collaboration of ALBA staff A.M. and P.R-H. acknowledge computing time provided by Red Espanola de Supercomputacion (RES) and MALTA-Cluster. J.A.S. acknowledges financial support through the Juan de la Cierva fellowship. We are particularly grateful to Angel Vegas for stimulating discussions and critical reading of this manuscript.SantamarĂa PĂ©rez, D.; Errandonea, D.; Gomis, O.; Sans Tresserras, JĂ.; Pereira, ALJ.; ManjĂłn Herrera, FJ.; Popescu, C.... (2015). Crystal structure of sinhalite MgAlBO4 under high pressure. Journal of Physical Chemistry C. 119(12):6777-6784. https://doi.org/10.1021/jp512131eS677767841191
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