302 research outputs found
Characterization of function spaces via low regularity mollifiers
Smoothness of a function can be measured in
terms of the rate of convergence of to , where
is an appropriate mollifier. In the framework of fractional Sobolev
spaces, we characterize the "appropriate" mollifiers. We also obtain sufficient
conditions, close to being necessary, which ensure that is adapted to a
given scale of spaces. Finally, we examine in detail the case where is a
characteristic function
Asymptotic behavior of critical points of an energy involving a loop-well potential
We describe the asymptotic behavior of critical points of when . Here, is a
Ginzburg-Landau type potential, vanishing on a simple closed curve .
Unlike the case of the standard Ginzburg-Landau potential ,
studied by Bethuel, Brezis and H\'elein, we do not assume any symmetry on
or . In order to overcome the difficulties due to the lack of symmetry,
we develop new tools which might be of independent interest
Density in
Let be a smooth bounded domain in ,
0\textless{}s\textless{}\infty and 1\le p\textless{}\infty. We prove that
is dense in except when 1\le sp\textless{}2 and . The main
ingredient is a new approximation method for -maps when
s\textless{}1. With 0\textless{}s\textless{}1, 1\le p\textless{}\infty
and sp\textless{}n, a ball, and a general compact connected
manifold, we prove that is dense in
if and only if . This supplements
analogous results obtained by Bethuel when , and by Bousquet, Ponce and
Van Schaftingen when [General domains have been treated
by Hang and Lin when ; our approach allows to extend their result to
s\textless{}1.] The case where s\textgreater{}1, , is
still open.Comment: To appear in J. Funct. Anal. 49
Existence of critical points with semi-stiff boundary conditions for singular perturbation problems in simply connected planar domains
Let be a smooth bounded simply connected domain in .
We investigate the existence of critical points of the energy ,
where the complex map has modulus one and prescribed degree on the
boundary. Under suitable nondegeneracy assumptions on , we prove
existence of critical points for small . More can be said when the
prescribed degree equals one. First, we obtain existence of critical points in
domains close to a disc. Next, we prove that critical points exist in "most" of
the domains
Design of a knowledge and management system for starch bioconversion
AbstractIn this paper a knowledge acquisition and management system (KAMS) which allows the collection, analysis, ordering and storage of informations generated at starch liquefaction was developed. KAMS was structured on three levels: PostgreSQL as a backend, D2RQ as middle tier and Seaside as frontend. The system was used to store knowledge about the liquefaction process with the goal to be used as a decision support system in chosing the condition for this operation. The tests had shown that the implemented KAMS provides support for: Distributed acquisition of the scientific data generated by the researchers; Structured data storage; Support for the generation and storage of knowledge on the starch bioconversion
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