1,011 research outputs found
Global L^r -estimates and regularizing effect for solutions to the p(t,x)-Laplacian systems
No full textWe consider the initial boundary value problem for the p(t,x)-Laplacian system in a bounded domain. If the initial data belongs to L^{r_0}, r_0≥2, we prove a global L^{r_0}-regularity result uniformly in t>0 that, in the particular case r_0=infty, gives a maximum modulus theorem. Under the assumption p−=inf p(t,x)>2n/(n+r_0), we also study L^{r_0}−L^r estimates for the solution, for r≥r_0
On the regularity of solution to the time-dependent p-Stokes system
No full textIn this paper we consider the time evolutionary p-Stokes problem in a smooth and bounded domain. This system models the unsteady motion or certain non-Newtonian incompressible fluids in the regime of slow motions, when the convective term is negligible. We prove results of space/time regularity, showing that first-order time-derivatives and second-order space-derivatives of the velocity and first-order space-derivatives of the pressure belong to rather natural Lebesgue spaces
Cotilting versus pure-injective modules
No full textLet R and S be arbitrary associative rings. A left R-module W-R is said to be cotilting if the class of modules cogenerated by W-R coincides with the class of modules for which the functor Ext(R)(1)(-, W) vanishes. In this paper we characterize the cotilting modules which are pure-injective. The two notions seem to be strictly connected: Indeed all the examples of cotilting modules known in the literature are pure-injective. We observe that if W-R(S) is a pure-injective cotilting bimodule, both R and S are semiregular rings and we give a characterization of the reflexive modules in terms of a suitable "linear compactness" notion
Natural second-order regularity for parabolic systems with operators having (p,δ)-structure and depending only on the symmetric gradient
No full textIn this paper we consider parabolic problems with stress tensor depending only on the symmetric gradient. By developing a new approximation method (which allows to use energy-type methods typical for linear problems) we provide an approach to obtain global regularity results valid for general potential operators with (p,delta)-structure, for all p>1 and for all delta>0. In this way we prove ``natural'' second order spatial regularity -- up to the boundary -- in the case of homogeneous Dirichlet boundary conditions. The regularity results, are presented with full details for the parabolic setting in the case p>2. However, the same method also yields regularity in the elliptic case and for
The Complier Pays Principle: The Limits of Fiscal Approaches Toward Sustainable Forest Management
No full textThis paper examines the role and impact of taxation on sustainable forest management. It is shown that fiscal instruments neither reinforce nor substitute for traditional regulatory approaches and can actually undermine sustainability. The paper uses the reasoning at the root of the Faustmann solution to draw conclusions on the incentives for sustainable tropical forest exploitation. It proposes a bond mechanism as an alternative market-based instrument to encourage sustainable forest logging while reducing monitoring costs. Copyright 2001, International Monetary Fund
Optimal error estimate for semi-implicit space-time discretization for the equations describing incompressible generalized Newtonian fluids
No full textIn this paper we study the numerical error arising in space-time approximation of unsteady power-law non-Newtonian fluids. A semi-implicit time discretization scheme, coupled with space discretization made with conforming finite elements is analyzed. The main result, which improves previous suboptimal estimates as those in [A.~Prohl, and M.~Ruzicka, SIAM J. Numer. Anal., 39 (2001), pp.~214--249] is the optimal O(k+h) error-estimate valid in the wide range pin]3/2,2], where k is the time-step and h the mesh-size.
Our results hold in three-dimensional domains (with periodic boundary conditions), are uniform with respect to the degeneracy parameter delta of the extra stress tensor, and a stability h-k-coupling depending on p is also needed
On time versus size for monotone dynamic monopolies in regular topologies
No full textJournal of Discrete Algorithm
Space-time discretization for nonlinear parabolic systems with p-structure
No full textIn this paper we consider nonlinear parabolic systems with elliptic part which can be also degenerate. We prove optimal error estimates for smooth enough solutions. The main novelty, with respect to previous results, is that we obtain the estimates directly without introducing intermediate semi-discrete problems. In addition, we prove the existence of solutions of the continuous problem with the requested regularity, if the data of the problem are smooth enough
- …
