1,946 research outputs found
Inequalities and bounds for the eigenvalues of the sub-Laplacian on a strictly pseudoconvex CR manifold
We establish inequalities for the eigenvalues of the sub-Laplace operator
associated with a pseudo-Hermitian structure on a strictly pseudoconvex CR
manifold. Our inequalities extend those obtained by Niu and Zhang
\cite{NiuZhang} for the Dirichlet eigenvalues of the sub-Laplacian on a bounded
domain in the Heisenberg group and are in the spirit of the well known
Payne-P\'{o}lya-Weinberger and Yang universal inequalities.Comment: To appear in Calculus of variations and Partial Differential
Equation
On the Supersymplectic Homogeneous Superspace Underlying the OSp(1/2) Coherent States
In this work we extend Onofri and Perelomov's coherent states methods to the
recently introduced coherent states. These latter are shown to be
parametrized by points of a supersymplectic supermanifold, namely the
homogeneous superspace , which is clearly identified with a
supercoadjoint orbit of by exhibiting the corresponding equivariant
supermoment map. Moreover, this supermanifold is shown to be a nontrivial
example of Rothstein's supersymplectic supermanifolds. More precisely, we show
that its supersymplectic structure is completely determined in terms of
-invariant (but unrelated) K\"ahler -form and K\"ahler metric on
the unit disc. This result allows us to define the notions of a superK\"ahler
supermanifold and a superK\"ahler superpotential, the geometric structure of
the former being encoded into the latter.Comment: 19 pgs, PlainTeX, Preprint CRM-185
Comparison of different Multiple-criteria decision analysis methods in the context of conceptual design: application to the development of a solar collector structure
At each stage of the product development process, the designers are facing an important task which consists of decision making. Two cases are observed: the problem of concept selection in conceptual design phases and, the problem of pre-dimensioning once concept choices are made. Making decisions in conceptual design phases on a sound basis is one of the most difficult challenges in engineering design, especially when innovative concepts are introduced. On the one hand, designers deal with imprecise data about design alternatives. On the other hand, design objectives and requirements are usually not clear in these phases. The greatest opportunities to reduce product life cycle costs usually occur during the first conceptual design phases. The need for reliable multi-criteria decision aid (MCDA) methods is thus greatest at early conceptual design phases. Various MCDA methods are proposed in the literature. The main criticism of these methods is that they usually yield different results for the same problem. In this work, an analysis of six MCDA methods (weighed sum, weighted product, Kim & Lin, compromise programming, TOPSIS, and ELECTRE I) was conducted. Our analysis was performed via an industrial case of solar collector structure development. The objective is to define the most appropriate MCDA methods in term of three criteria: (i) the consistency of the results, (ii) the ease of understanding and, (iii) the adaptation of the decision type. The results show that TOPSIS is the most consistent MCDA method in our case
Critical review of multi-criteria decision aid methods in conceptual design phases: application to the development of a solar collector structure
At each stage of the product development process, the designers are facing an important task which consists of decision making. Two cases are observed: the problem of concept selection in conceptual design phases and, the problem of pre-dimensioning once concept choices are made. Making decisions in conceptual design phases on a sound basis is one of the most difficult challenges in engineering design, especially when innovative concepts are introduced. On the one hand, designers deal with imprecise data about design alternatives. On the other hand, design objectives and requirements are usually not clear in these phases. The greatest opportunities to reduce product life cycle costs usually occur during the first conceptual design phases. The need for reliable multi-criteria decision aid (MCDA) methods is thus greatest at early conceptual design phases. Various MCDA methods are proposed in the literature. The main criticism of these methods is that they usually yield different results for the same problem [22,23,25]. In this work, an analysis of six MCDA methods (weighed sum, weighted product, Kim & Lin, compromise programming, TOPSIS, and ELECTRE I) was conducted. Our analysis was performed via an industrial case of solar collector structure development. The objective is to define the most appropriate MCDA methods in term of three criteria: (i) the consistency of the results, (ii) the ease of understanding and, (iii) the adaptation of the decision type. The results show that TOPSIS is the most consistent MCDA method in our case
Diagrams Editors Specification Using Reusable Components
International audienceModel Driven Engineering (MDE) encourages the use of graphical modeling tools, which facilitate the development process from modeling to coding. Such tools can be designed using the MDE approach into metamodeling environments called metaCASE tools. It turned out that the implementation of such tools is made by technologies which need as much effort as resources for modest results, requiring in most cases additional programming efforts for their adaptation. Some of these technologies are suffering from weaknesses especially in terms of reusability. In this context, this paper proposes an evaluation for modeling editors. It discusses the current state of the art, compares what was done in every tool that we evaluate; according to relevant criteria; and propose "MID": a set of metamodels supporting the easy specification of modeling editors by means of reusable components
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