Search results for "Matrices"
showing 10 items of 155 documents
Unified theory for analysis of curved thin-walled girders with open and closed cross section through HSA method
2016
Abstract The behaviour of thin-walled structures is deeply influenced by non-uniform torsion and cross section distortion. In this paper the extension of the Hamiltonian Structural Analysis (HSA) Method to thin-walled straight and curved beams is presented. The proposed method solves the structural elastic problem of thin-walled beams through the definition of a Hamiltonian system composed of 1st order differential equations. The method allows engineers to solve the elastic problem by introducing the degrees of freedom and the corresponding compatibility equations, founding equilibrium equations in the variational form. The methodology is explained in the framework of the so-called Generali…
The Role of Covariance Matrix Forecasting Method in the Performance of Minimum-Variance Portfolios
2014
Providing a more accurate covariance matrix forecast can substantially improve the performance of optimized portfolios. Using out-of-sample tests, in this paper, we evaluate alternative covariance matrix forecasting methods by looking at (1) their forecast accuracy, (2) their ability to track the volatility of the minimum-variance portfolio, and (3) their ability to keep the volatility of the minimum-variance portfolio at a target level. We find large differences between the methods. Our results suggest that shrinkage of the sample covariance matrix improves neither the forecast accuracy nor the performance of minimum-variance portfolios. In contrast, switching from the sample covariance ma…
An Investigation of the Robustness in the Travelling Salesman Problem Routes Using Special Structured Matrices
2020
In this study, the robustness of the Travelling Salesman Problem (TSP) routes is investigated by recognising the special combinatorial structures of Kalmanson matrices. A recognition algorithm encompassing three procedures based on combinatorial and linear programming (LP) is developed and executed on several randomly generated instances. These procedures produce three lower bounds which provide guarantees on the optimality of the solutions. Computational experiments show that the proposed LP-based procedure performs efficiently well across all problem dimensions and provides the best lower bounds to the TSP. This is supported by an average deviation of less than 7% between the TSP tour len…
Analytical study and exposure to Fusarium mycotoxins = Estudio analítico y de exposición a micotoxinas de Fusarium
2015
Las micotoxinas son metabolitos secundarios de determinadas especies fúngicas que se encuentran habitualmente en los alimentos. El Reglamento No. 1881/2006 de la Comisión Europea, parcialmente modificado por posteriores Reglamentos, establece los contenidos máximos de micotoxinas para diferentes productos alimenticios. La introducción de estas normas pone de manifiesto el interés por el conocimiento de valores relativos a la concentración de estos tóxicos para poder evaluar riesgos y adoptar las medidas necesarias para proteger la salud de los consumidores. Los productos agrícolas contaminados, especialmente cereales y sus derivados, son la principal fuente de micotoxinas en la dieta de la …
On Non-Gaussian limiting laws for certain statistics of Wigner Matrices
2013
This paper is a continuation of our papers [12-14] in which the limiting laws of fluctuations were found for the linear eigenvalue statistics Tr j(M(n)) and for the normalized matrix elements √n̅jjj(M(n)) of differentiable functions of real symmetric Wigner matrices M(n) as n →∞. Here we consider another spectral characteristic of Wigner matrices, xnA [j] = Tr j(M(n))A(n), where {A(n)}∞n=1 is a certain sequence of non-random matrices. We show first that if M(n) belongs to the Gaussian Orthogonal Ensemble, then xnA [j] satisfies the Central Limit Theorem. Then we consider Wigner matrices with i.i.d. entries possessing the entire characteristic function and find the limiting probability law f…
Determinant and inverse of a sum of matrices with applications in economics and statistics
1978
In this note we present some useful tools concerning the determinant and the inverse of the sum of two matrices. Some of the results shown here are found in the statistical and econometric literature, but often without proof and without a clear statement of the conditions under which they hold. Some other results, however, are believed to be original. A number of applications in the fields of economics and statistics are given.
De Cratyle à la TME : une longue tradition dans le débat sur la motivation ou l’arbitraire des mots
2016
In the specialized literature, the concepts of motivation and arbitrariness refer to very different realities. Using some essential readings, we endeavour to clarify these points in the "motivated vs arbitrary nature of lexical forms" debate inaugurated in Plato's Cratylus. Amongst other things, these reveal that the lexical motivation phenomenon is more complex than the supporters of the Saussurian doxa of arbitrariness would have us believe. Even if a considerable amount of time separates the first forms of language from the most ancient linguistic forms available to us and any attempt to reconstruct these original forms is based upon an illusion, it is, nevertheless, possible to decipher…
Matrices de pondérations et contexte spatio-temporel en économétrie spatiale
2013
International audience
Study of acoustic properties and impact behavior of porous materials homogeneous type metal foams and inhomogeneous
2015
This work is concerned with the theoretical and experimental study of the acoustical properties of macroscopically homogenous and inhomogeneous porous media as well as their mechanical response to impacts. The model of Johnson - Champoux - Allard appeared adapted for the acoustical modeling. This model, associated with a recently developed approach involving the concept of parallel transfer matrices has lead to a new approach of macroscopically inhomogeneous porous materials based on “mixtures of materials”. Furthermore, a parametric study of the absorption coefficient as a function of porosity and frequency has been proposed. The maximums of absorption as well as the envelop of the absorpt…
ORNAMENTAL SIGN LANGUAGE IN THE FIRST ORDER TRACERY BELTS
2010
18 pages; We consider ornamental sign language of first order where principles of sieve displacement, of asymmetric building blocks as base of ornament symmetry, color exchangeability and side equivalence principles work. The generic aspects of sieve and genesis of ornamental pattern and ornament sign in it are discussed. The hemiolia principle for ornamental genesis is introduced. The discoverer of most of these principles were artist Modris Tenisons [4, 5, 6, 7 (refs. 23, 24), 8 (ref. 65)]. Here we apply systematical research using simplest mathematical arguments. We come to conclusions that mathematical argument in arising ornament is of much more significance than simply symmetries in i…