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Search Results: 1 - 4 of 4 matches for " Dahlby "
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Too many municipalities?
Dahlby, Bev;
Revista Brasileira de Economia , 2011, DOI: 10.1590/S0034-71402011000100002
Abstract: does democracy lead to the creation of too many municipalities? we analyze this issue within the context of the alesina e spolaore (1997) model where the quality of municipal services deteriorates with the distance from the center of a municipality. individuals can vote in a referendum to split an existing municipality. we show that social welfare will decline when municipalities are split if the level of the public service, as chosen by the median voter, is lower in the new smaller municipalities. in general, the model indicates that there may be a democratic bias in favour of creating too many municipalities.
A general framework for deriving integral preserving numerical methods for PDEs
Morten Dahlby,Brynjulf Owren
Mathematics , 2010,
Abstract: A general procedure for constructing conservative numerical integrators for time dependent partial differential equations is presented. In particular, linearly implicit methods preserving a time discretised version of the invariant is developed for systems of partial differential equations with polynomial nonlinearities. The framework is rather general and allows for an arbitrary number of dependent and independent variables with derivatives of any order. It is proved formally that second order convergence is obtained. The procedure is applied to a test case and numerical experiments are provided.
Plane wave stability of some conservative schemes for the cubic Schr?dinger equation
Morten Dahlby,Brynjulf Owren
Mathematics , 2010,
Abstract: The plane wave stability properties of the conservative schemes of Besse and Fei et al. for the cubic Schr\"{o}dinger equation are analysed. Although the two methods possess many of the same conservation properties, we show that their stability behaviour is very different. An energy preserving generalisation of the Fei method with improved stability is presented.
Preserving multiple first integrals by discrete gradients
Morten Dahlby,Brynjulf Owren,Takaharu Yaguchi
Mathematics , 2010, DOI: 10.1088/1751-8113/44/30/305205
Abstract: We consider systems of ordinary differential equations with known first integrals. The notion of a discrete tangent space is introduced as the orthogonal complement of an arbitrary set of discrete gradients. Integrators which exactly conserve all the first integrals simultaneously are then defined. In both cases we start from an arbitrary method of a prescribed order (say, a Runge-Kutta scheme) and modify it using two approaches: one based on projection and one based one local coordinates. The methods are tested on the Kepler problem.
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