Modeling elastic wave propagation in fluid-filled boreholes drilled in nonhomogeneous media: BEM – MLPG versus BEM-FEM coupling

The efficiency of two coupling formulations, the boundary element method (BEM)-meshless local Petrov–Galerkin (MLPG) versus the BEM-finite element method (FEM), used to simulate the elastic wave propagation in fluid-filled boreholes generated by a blast load, is compared. The longitudinal geometry is assumed to be invariant in the axial direction (2.5D formulation). The material properties in the vicinity of the borehole are assumed to be nonhomogeneous as a result of the construction process and the ageing of the material. In both models, the BEM is used to tackle the propagation within the fluid domain inside the borehole and the unbounded homogeneous domain. The MLPG and the FEM are used to simulate the confined, damaged, nonhomogeneous, surrounding borehole, thus utilizing the advantages of these methods in modeling nonhomogeneous bounded media. In both numerical techniques the coupling is accomplished directly at the nodal points located at the common interfaces. Continuity of stresses and displacements is imposed at the solid–solid interface, while continuity of normal stresses and displacements and null shear stress are prescribed at the fluid–solid interface. The performance of each coupled BEM-MLPG and BEM-FEM approach is determined using referenced results provided by an analytical solution developed for a circular multi-layered subdomain. The comparison of the coupled techniques is evaluated for different excitation frequencies, axial wavenumbers and degrees of freedom (nodal points).Ministerio de Economía y Competitividad BIA2013-43085-PCentro Informático Científico de Andalucía (CICA

RESEARCH IN ECONOMICS IN SPAIN: RANKINGS OF INSTITUTIONS AND AUTHORS

In this paper we analyse the research in Economics in Spain during the 1990s considering the contributions of both Spanish and foreign economist who have worked in Spain during that period. To do so, we use different bibliometric indicators in order to elaborate rankings for both institutions and researchers. These rankings can be useful for several potentials users such as: a) Evaluation Agencies and Funding Bodies to help them in grant-allocation decisions; b) Graduate students who whish to choose the right institution to complete their postgraduate education, and c) Young Ph Ds who have entered the academic job market and need information about the research perfomance of different institutions.

Sequential decisions in the college admissions problem

This paper models a contractual process by a sequential mechanism, which mimics matching procedures for many-to-one real-life matching problems. In this framework, we provide a family of mechanisms implementing the student-optimal matching in Subgame Perfect Equilibrium (SPE).Alcalde’s work is partially supported by the Institut Valencia` d’Investigacions Econo`miques and the Spanish Ministerio de Educacio´n y Cultura under project BEC 2001-0535. Romero-Medina acknowledges financial support from the Spanish Ministerio de Educacio´n y Cultura under project BCE-2002-02194 and Comunidad de Madrid under project 02303.Publicad

Sequential Decisions in the College Admissions Problem

This paper studies sequential mechanisms which mimic matching prodedures for many-to-one real life matching markets. We provide a family of mechanisms implementing the student´optimal allocation in Subgame Perfect Equilibriu

Simple Mechanisms to Implement the Core of College Admisions Problems

This paper analyzes simple mechanisms implementing (subselections of) the core correspondence of matching markets. We provide a sequential mechanism which mimics a matching procedure for many-to-one real life matching markets. We show that only core allocations should be attained when agents act strategically when faced with this mechanism. We also provide a second mechanism to implement the core correspondence in Subgame Perfect Equilibrium.Alcalde’s work is partially supported by the Institut Valencia d’Investigacions Econòmiques and DGICYT under project PB 97–0131. Romero–Medina acknowledges financial support from the Instituto de Estudios Fiscales and DGICYT under project PB 92–0590.Publicad

Harvesting Thermal Fluctuations: Activation Process Induced by a Nonlinear Chain in Thermal Equilibrium

We present a model in which the immediate environment of a bistable system is a molecular chain which in turn is connected to a thermal environment of the Langevin form. The molecular chain consists of masses connected by harmonic or by anharmonic springs. The distribution, intensity, and mobility of thermal fluctuations in these chains is strongly dependent on the nature of the springs and leads to different transition dynamics for the activated process. Thus, all else (temperature, damping, coupling parameters between the chain and the bistable system) being the same, the hard chain may provide an environment described as diffusion-limited and more effective in the activation process, while the soft chain may provide an environment described as energy-limited and less effective. The importance of a detailed understanding of the thermal environment toward the understanding of the activation process itself is thus highlighted

Thermodynamic analysis of unimer-micelle and sphere-to-rod micellar transitions of aqueous solutions of sodium dodecylbenzenesulfonate

Temperature dependence of specific conductivity of sodium dodecylbenzenesulfonate (NaDBS) aqueous solutions was analyzed. Two breaks on the plot appeared for all temperature, which suggest two micellar transitions. This has been corroborated by surface tension measurements. The first transition concentration occurs at the critical micelle concentration (CMC), whilst the second critical concentration (so-called transition micellar concentration, TMC) is due to a sphere-to-rod micelles transition. The dependence of CMC and TMC on the temperature allows the computation of the corresponding thermodynamic functions: Gibbs free energy, enthalpy and entropy changes. For the CMC, enthalpy and entropy increments were found that decrease with the temperature values. However, an anomalous behavior was obtained for the TMC, where both ΔS0 and ΔH0 values raised with the temperature increase. However, for both transitions, an (enthalpy + entropy) compensation is observed. These results will be compared with similar systems reported in the literature

Detection of Non-Technical Losses in Smart Distribution Networks: a Review

With the advent of smart grids, distribution utilities have initiated a large deployment of smart meters on the premises of the consumers. The enormous amount of data obtained from the consumers and communicated to the utility give new perspectives and possibilities for various analytics-based applications. In this paper the current smart metering-based energy-theft detection schemes are reviewed and discussed according to two main distinctive categories: A) system statebased, and B) arti cial intelligence-based.Comisión Europea FP7-PEOPLE-2013-IT

Nuevas aportaciones a la definición del Círculo del Estrecho: la cultura material a través de algunos centros alfareros (ss. VI-I a.n.e.)

El objetivo de este trabajo es poner de relieve la existencia de una serie de rasgos comunes en la cultura material cerámica y en las estructuras de producción de éstas -similitudes comerciales por tantoentre varios yacimientos de lo que se ha venido denominando “Círculo del Estrecho” durante época púnica y tardopúnica, lo que nos servirá para analizar distintas interpretaciones de esta zona geopolítica del Extremo Occidente Mediterráneo.With this paper we will try to emphazise some similarities about ceramics industry -commercial activities- between some archaeological sites included in the "Círculo del Estrecho". This information will help us to analyse some interpretations given to the historical evolution of this area of the Western Mediterranean Sea

A problem on the approximation of n-roots based on the Viète's work

In this paper, after giving a brief approach about the historical question of how different authors and cultures handled approximations of the n-th root of N := An + R, we consider the particular case of the approximation of n v N by A + R d (here n, A, d are positive integers, with n = 2, d = (A + 1)n - An - 1, and 0 < R = d), explicitly considered by Viète in his De Numerosa Potestatum. Viète established in one of the precepts of his work that the n-th root is placed between A + R d+1 and A+ R d . Indeed, it is easily seen that, of course, A + R d+1 = n v N , but unfortunately n v N can be greater than A + R d when n = 3. Then the question arises whether we are able or not of determining what values of R (fixing the integer values n and A, so also d) give a true approximation by excess when n v N is estimated as A + R d , that is, to find those values of R producing an excess in relation with the exact value of the root. We give a complete answer to the cases n = 7, and we present without proof the main result for a general n.This work has been supported by the grant MTM2017-84079-P (AEI/FEDER, UE) from Ministerio de Ciencia, Innovación y Universidades (Spain).Postprint (published version