441 research outputs found
Lack of compactness in the 2D critical Sobolev embedding, the general case
This paper is devoted to the description of the lack of compactness of the
Sobolev embedding of in the critical Orlicz space {\cL}(\R^2). It
turns out that up to cores our result is expressed in terms of the
concentration-type examples derived by J. Moser in \cite{M} as in the radial
setting investigated in \cite{BMM}. However, the analysis we used in this work
is strikingly different from the one conducted in the radial case which is
based on an estimate far away from the origin and which is no
longer valid in the general framework. Within the general framework of
, the strategy we adopted to build the profile decomposition in
terms of examples by Moser concentrated around cores is based on capacity
arguments and relies on an extraction process of mass concentrations. The
essential ingredient to extract cores consists in proving by contradiction that
if the mass responsible for the lack of compactness of the Sobolev embedding in
the Orlicz space is scattered, then the energy used would exceed that of the
starting sequence.Comment: Submitte
On the lack of compactness in the 2D critical Sobolev embedding
This paper is devoted to the description of the lack of compactness of
in the Orlicz space. Our result is expressed in terms of the
concentration-type examples derived by P. -L. Lions. The approach that we adopt
to establish this characterization is completely different from the methods
used in the study of the lack of compactness of Sobolev embedding in Lebesgue
spaces and take into account the variational aspect of Orlicz spaces. We also
investigate the feature of the solutions of non linear wave equation with
exponential growth, where the Orlicz norm plays a decisive role.Comment: 38 page
Planning for the future of Masmoudi’s business family
The following work project has the purpose of advising the Masmoudi family to plan for the
future. The family and business were presented, the current situation of family governance
was assessed, and the need for developing a family constitution was identified. For the
purpose of developing such document, qualitative data from the members of the family was
collected and analyzed, to eventually present a draft of the constitution. In the process, the
concepts referred to in the literature review regarding family business and family business
governance, were demonstrated in the discussions with the Masmoudi’s family members
A Taguchi method application for the part routing selection in Generalized Group Technology: A case Study
Cellular manufacturing (CM) is an important application of group technology (GT) that can be used to enhance both flexibility and efficiency in today’s small-to-medium lot production environment. The crucial step in the design of a CM system is the cell formation (CF) problem which involves grouping parts into families and machines into cells. The CF problem are increasingly complicated if parts are assigned with alternative routings (known as generalized Group Technology problem). In most of the previous works, the route selection problem and CF problem were formulated in a single model which is not practical for solving large-scale problems. We suggest that better solution could be obtained by formulating and solving them separately in two different problems. The aim of this case study is to apply Taguchi method for the route selection problem as an optimization technique to get back to the simple CF problem which can be solved by any of the numerous CF procedures. In addition the main effect of each part and analysis of variance (ANOVA) are introduced as a sensitivity analysis aspect that is completely ignored in previous research.Cellular Manufacturing; generalized Group Technology; route selection problem; Taguchi method; ANOVA; sensitivity analysis
An improvement of a cellular manufacturing system design using simulation analysis
Cell Formation (CF) problem involves grouping the parts into part families and machines into manufacturing cells, so that parts with similar processing requirements are manufactured within the same cell. Many researches have suggested methods for CF. Few of these methods; have addressed the possible existence of exceptional elements (EE) in the solution and the effect of correspondent intercellular movement, which cause lack of segregation among the cells. This paper presents a simulation-based methodology, which takes into consideration the stochastic aspect in the cellular manufacturing (CM) system, to create better cell configurations. An initial solution is developed using any of the numerous CF procedures. The objective of the proposed method which provides performances ratings and cost-effective consist in determine how best to deal with the remaining EE. It considers and compares two strategies (1) permitting intercellular transfer and (2) exceptional machine duplication. The process is demonstrated with a numerical exampleCell Formation; Exceptional Elements; Simulation; Alternative costs; Improvement
Formation of machine groups and part families in cellular manufacturing systems using a correlation analysis approach
The important step in the design of a cellular manufacturing (CM) system is to identify the part families and machine groups and consequently to form manufacturing cells. The scope of this article is to formulate a multivariate approach based on a correlation analysis for solving cell formation problem. The proposed approach is carried out in three phases. In the first phase, the correlation matrix is used as similarity coefficient matrix. In the second phase, Principal Component Analysis (PCA) is applied to find the eigenvalues and eigenvectors on the correlation similarity matrix. A scatter plot analysis as a cluster analysis is applied to make simultaneously machine groups and part families while maximizing correlation between elements. In the third stage, an algorithm is improved to assign exceptional machines and exceptional parts using respectively angle measure and Euclidian distance. The proposed approach is also applied to the general Group Technology (GT) problem in which exceptional machines and part are considered. Furthermore, the proposed approach has the flexibility to consider the number of cells as a dependent or independent variable. Two numerical examples for the design of cell structures are provided in order to illustrate the three phases of proposed approach. The results of a comparative study based on multiple performance criteria show that the present approach is very effective, efficient and practical.cellular manufacturing; cell formation; correlation matrix; Principal Component Analysis; exceptional machines and parts
A New Combined Framework for the Cellular Manufacturing Systems Design
Cellular Manufacturing (CM) system has been recognized as an efficient and effective way to improve productivity in a factory. In recent years, there have been continuous research efforts to study different facet of CM system. The literature does not contain much published research on CM design which includes all design aspects. In this paper we provide a framework for the complete CM system design. It combines Axiomatic Design (AD) and Experimental Design (ED) to generate several feasible and potentially profitable designs. The AD approach is used as the basis for establishing a systematic CM systems design structure. ED has been a very useful tool to design and analyze complicated industrial design problems. AD helps secure valid input-factors to the ED. An element of the proposed framework is desmontrate through a numerical example for cell formation with alternative process.Cellular manufacturing; Design methodology Axiomatic Design; Experimental Design.
Energy scattering for 2D critical wave equation
We investigate existence and asymptotic completeness of the wave operators
for nonlinear Klein-Gordon and Schr\"odinger equations with a defocusing
exponential nonlinearity in two space dimensions. A certain threshold is
defined based on the value of the conserved Hamiltonian, below which the
exponential potential energy is dominated by the kinetic energy via a
Trudinger-Moser type inequality.
We prove that if the energy is below or equal to the critical value, then the
solution approaches a free Klein-Gordon solution at the time infinity. The
interesting feature in the critical case is that the Strichartz estimate
together with Sobolev-type inequalities can not control the nonlinear term
uniformly on each time interval, but with constants depending on how much the
solution is concentrated. Thus we have to trace concentration of the energy
along time, in order to set up favorable nonlinear estimates, and then to
implement Bourgain's induction argument. We show the same result for the
"subcritical" nonlinear Schr\"odinger equation.Comment: 33 pages, submitte
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