37,441 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
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
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
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 Behavioral Foundation for Models of Evolutionary Drift
Binmore and Samuelson (1999) have shown that perturbations (drift) are crucial to study the stability properties of Nash equilibria. We contribute to this literature by providing a behavioural foundation for models of evolutionary drift. In particular, this article introduces a microeconomic model of drift based on the similarity theory developed by Tversky (1977), Kahneman and Tversky (1979) and Rubinstein (1988),(1998). An innovation with respect to those works is that we deal with similarity relations that are derived from the perception that each agent has about how well he is playing the game. In addition, the similarity relations are adapted to a dynamic setting. We obtain different models of drift depending on how we model the agent´s assessment of his behaviour in the game. The examples of the ultimatum game and the chain-store game are used to show the conditions for each model to stabilize elements in the component of Nash equilibria that are not subgame- perfect. It is also shown how some models approximate the laboratory data about those games while others match the data.similarity relations, drift, Nash equilibrium, selection dynamics, learning
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
The New Energy System in the Mexican Constitution
This study analyzes the new legal framework and definitions governing Mexico's energy sector as a result of the constitutional reform, and the implications for the hydrocarbons and electrical sectors. This paper is part of a Baker Institute Mexico Center research project examining the rule of law in Mexico (https://www.bakerinstitute.org/the-rule-of-law/) and the challenges it poses to implementing the country's energy reform
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