36,744 research outputs found
Numerical resolution of an exact heat conduction model with a delay term
In this paper we analyze, from the numerical point of view, a dynamic thermoelastic problem. Here, the so-called exact heat conduction model with a delay term is used to obtain the heat evolution. Thus, the thermomechanical problem is written as a coupled system of partial differential equations, and its variational formulation leads to a system written in terms of the velocity and the temperature fields. An existence and uniqueness result is recalled. Then, fully discrete approximations are introduced by using the classical finite element method to approximate the spatial variable and the implicit Euler scheme to discretize the time derivatives. A priori error estimates are proved, from which the linear convergence of the algorithm could be derived under suitable additional regularity conditions. Finally, a two-dimensional numerical example is solved to show the accuracy of the approximation and the decay of the discrete energy.Peer ReviewedPostprint (published version
Using high-frequency data and time series models to improve yield management
We show the potential contribution of time series models (TSM) to the analysis of high frequency (less than monthly) time series of economic activity. The evolution of the series is induced by stable patterns of behavior of economic agents; but these patterns are so complex that simple smoothing techniques or subjective forecasting can not consider all underlying factors and TSM are needed if a full efficient analysis is to be carried out. The main ideas are illustrated with an apllication to Spanish daily electricity consumption
Model based measures of contemporaneous economic growth
In short term economic reports the use of different growth rate measures is misleading. This paper studies the question of using an unique measure -underlying growth-, which should be smoothed and in phase with the monthly increments of the
corresponding variable. All possible solutions require the use of forecasts at the end of the sample. The paper proposes the use of models to obtain forecasts¡ then the contemporaneous underlying growth is a model based measure. An evaluation of the effects of the last innovations in the underlying growth can be obtained by comparing its last estimation with previous one. An example of its application, based on inflation analysis, is presented
EFFECTS OF TAX REFORMS IN A SHIRKING MODEL WITH UNION BARGAINING
In this paper we introduce a progressive income tax in the shirking model with union bargaining presented by in Altenburg and Straub (2002). Indeed, we differentiate taxation on employees and employers for the fiscal policy analysis. The main results show that it is possible, with a constant revenue reform, to enhance employment by shifting the tax imposition towards lower firm taxation. And, that it is crucial to consider a proportional or progressive taxation on labour income in order to be able to analyse the effect on unemployment for a constant replacement rate.Labour taxation, union bargaining, efficiency wages
On localizations of quasi-simple groups with given countable center
A group homomorphism is a localization of if for every
homomorphism there exists a unique endomorphism
, such that (maps are acting on the
right). G\"{o}bel and Trlifaj asked in \cite[Problem 30.4(4), p. 831]{GT12}
which abelian groups are centers of localizations of simple groups. Approaching
this question we show that every countable abelian group is indeed the center
of some localization of a quasi-simple group, i.e. a central extension of a
simple group. The proof uses Obraztsov and Ol'shanskii's construction of
infinite simple groups with a special subgroup lattice and also extensions of
results on localizations of finite simple groups by the second author and
Scherer, Th\'{e}venaz and Viruel.Comment: 21 page
Generators and closed classes of groups
We show that in the category of groups, every singly-generated class which is
closed under isomorphisms, direct limits and extensions is also
singly-generated under isomorphisms and direct limits, and in particular is
co-reflective. We also establish several new relations between singly-generated
closed classes.Comment: 22 page
A Model of Evolutionay Drift
Drift appears to be crucial to study the stability properties of Nash equilibria in a component specifying different out-of-equilibrium behaviour. We propose a new microeconomic model of drift to be added to the learning process by which agents find their way to equilibrium. A key feature of the model is the sensitivity of the noisy agent to the proportion of agents in his player population playing the same strategy as his current one. We show that, 1. Perturbed Payoff-Positive and PayoffMonotone selection dynamics are capable of stabilizing pure non strict Nash equilibria in either singleton or nonsingleton component of equilibria; 2. The model is relevant to understand the role of drift in the behaviour observed in the laboratory for the Ultimatum Game and for predicting outcomes that can be experimentally tested. Hence, the selection dynamics model perturbed with the proposed drift may be seen as well as a new learning tool to understand observed behaviour.drift, Nash equilibrium, similarity relations, replicator dynam, learning
Doubts and equilibria
In real life strategic interactions decision-makers are likely to entertain doubts about the
degree of optimality of their play. To capture this feature of real choice-making, we present here
a model based on the doubts felt by an agent about how well is playing a game. The doubts are
coupled with (and mutually reinforced by) imperfect discrimination capacity, which we model
here by means of similarity relations. We assume that each agent builds procedural preferences
defined on the space of expected payoffsstrategy frequencies attached to his current strategy.
These preferences, together with an adaptive learning process lead to doubt-based selection
dynamic systems. We introduce the concepts of Mixed Strategy Doubt Equilibria, Mixed
Strategy Doubt-Full Equilibria and Mixed Strategy Doubtless Equilibria and show the
theoretical and the empirical relevance of these concept
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