Exponential decay in mixtures with localized dissipative term

In this note we prove the exponential decay of solutions of the equations of motion of a mixture of two linear isotropic one-dimensional elastic materials when the diffusive force is a function which depends on the point and can be localized. That means that the diffusive function can be zero in a part of the domain, but the coefficient that multiplies the relative velocity is always non-negative and the measure of the support is positive.     

Fast quantitative processing of particle image velocimetry photographs by a whole-field filtering technique

A fast quantitative processing of particle image velocimetry photographs by a whole-field spatial filtering technique is described. Photographs are observed through a conventional filtering setup. This produces fringe patterned images with each fringe corresponding to a fixed value of one velocity component. These images are acquired with a CCD camera and digitally processed to retrieve the fringe centerline positions. The interpolation of these data provides the velocity value on a grid of regularly spaced points.Photographs taken from a Rayleigh-Bénard convective flow have been processed with this technique and with a previously reported point-by-point technique. Results from both techniques compare well.This work was supported by Diputación General de Aragón under Grant No. PCB6-90     

A hybrid genetic algorithm for the resource-constrained project scheduling problem

In this paper we propose a Hybrid Genetic Algorithm (HGA) for the Resource-Constrained Project Scheduling Problem (RCPSP). HGA introduces several changes in the GA paradigm: a crossover operator specific for the RCPSP; a local improvement operator that is applied to all generated schedules; a new way to select the parents to be combined; and a two-phase strategy by which the second phase re-starts the evolution from a neighbour’s population of the best schedule found in the first phase. The computational results show that HGA is a fast and high quality algorithm that outperforms all state-of-the-art algorithms for the RCPSP known by the authors of this paper for the instance sets j60 and j120. And that it is competitive with other state-of-the-art heuristics for the instance set j30.     

A note on the two temperature theory with dual-phase-lag delay: Some exact solutions

In this note we present exact solutions of two initial-boundary value problems (IBVP)s in the setting of a recently-introduced theory of heat conduction, wherein the two temperature theory of the late 1960s is merged with Tzou’s dual-phase-lag flux relation. First, we solve a one-dimensional problem on a finite interval for a simple, parabolic initial condition. We then describe how to extend the analysis to the general three-dimensional case. In particular, it is demonstrated that the instability which generally arises in connection with the dual-phase-lag model can be avoided under this hybrid formulation.     

Spatial and continuous dependence estimates in linear viscoelasticity

In this paper we consider the problem determined by the anti-plane shear dynamic deformations for the linear theory of viscoelasticity. First, we prove existence of solutions of the problem determined in a semi-infinite strip. Then, we show that the rate of decay of the end effects in this problem is faster than that known for the Laplace equation. In the last section, we study the influence of the mass density on the decay of end effects.     

Time and work generalised precedence relationships in project scheduling with pre-emption: An application to the management of Service Centres

In this paper we present an application of project scheduling concepts and solution procedures for the solution of a complex problem that comes up in the daily management of many company Service Centres. The real problem has been modelled as a multi-mode resource-constrained project scheduling problem with pre-emption, time and work generalised precedence relationships with minimal and maximal time lags between the tasks and due dates. We present a complete study of work GPRs which includes proper definitions, a new notation and all possible conversions amongst them. Computational results that show the efficiency of the proposed hybrid genetic algorithm and the advantages of allowing pre-emption are also presented.     

A note on the spatial behavior for the generalized Tricomi equation

This short note is devoted to the study of the spatial decay estimates for the solutions of the generalized Tricomi equation. The relevance of this kind of study is that we obtain the decay for an equation which can be elliptic, parabolic and hyperbolic depending on the different points of the region. This equation is relevant in the study of fluids as well as for the anti-plane deformations of prestressed functionally graded linear elastic solids.     

Ab initio and experimental thermodynamic and kinetic study of proton-assisted bond activation in gaseous hydrocarbons: deconvolution of reaction efficiencies in the case of adamantane

1) Protonation at all possible sites of adamantane (C(10)H(16)) was studied at the MP2/6-311++G(3df,2p)//MP2/6-311++G(d,p) level. This provided values of the changes in the thermodynamic state functions for these processes. Whenever direct comparison was possible, the agreement with experimental data was very good. 2) By the same means, the reaction paths linking the various species obtained in these reactions were analyzed. 3) Fourier transform ion cyclotron resonance (FT-ICR) spectroscopy was used to determine the rate constants for proton transfer from 16 protonated reference bases to adamantane in the gas phase. Also, the rate constants for the formation of ionic products in these reactions were determined. 4) The experimental reaction rates were successfully predicted and refined on the basis of a simple mechanistic model based on the reaction profiles indicated above. 5) Our results hint at the potential usefulness of this approach for mechanistic studies.