Search results for "Computational Mathematic"

Figures of equilibrium in close binary systems

1992

The equilibrium configurations of close binary systems are analyzed. The autogravitational, centrifugal and tidal potentials are expanded in Clairaut's coordinates. From the set of the total potential angular terms an integral equations system is derived. The reduction of them to ordinary differential equations and the determination of the boundary conditions allow a formulation of the problem in terms of a single variable.

Energy dissipative characteristic schemes for the diffusive Oldroyd-B viscoelastic fluid

2015

Domain decomposition in the symmetric boundary element analysis

2002

Recent developments in the symmetric boundary element method (SBEM) have shown a clear superiority of this formulation over the collocation method. Its competitiveness has been tested in comparison to the finite element method (FEM) and is manifested in several engineering problems in which internal boundaries are present, i.e. those in which the body shows a jump in the physical characteristics of the material and in which an appropriate study of the response must be used. When we work in the ambit of the SBE formulation, the body is subdivided into macroelements characterized by some relations which link the interface boundary unknowns to the external actions. These relations, valid for e…

Elastic plastic analysis iterative solution

1998

The step-by-step analysis of finite element elastic plastic structures subjected to an assigned (quasi-static) loading history, is considered; it identifies with the well-known sequence of linear complementarity problems. An iterative technique devoted to solve the relevant linear complementarity problem is presented. It is based on the recursive solution of a suitable linear complementarity problem, deduced from the relevant one and easier than it. The procedure convergency is proved. Some noticing particular cases are examined. The physical meaning of the procedure is shown to be a plastic relaxation. The suitable numerical ranges for some check parameter values, to be utilized in the app…

The Calderón Problem for a Space-Time Fractional Parabolic Equation

2020

In this article we study an inverse problem for the space-time fractional parabolic operator $(\partial_t-\Delta)^s+Q$ with $0<s<1$ in any space dimension. We uniquely determine the unknown bounded...

Cardinal invariants of cellular Lindelof spaces

2018

A space X is said to be cellular-Lindelof if for every cellular family $$\mathcal {U}$$ there is a Lindelof subspace L of X which meets every element of $$\mathcal {U}$$ . Cellular-Lindelof spaces generalize both Lindelof spaces and spaces with the countable chain condition. Solving questions of Xuan and Song, we prove that every cellular-Lindelof monotonically normal space is Lindelof and that every cellular-Lindelof space with a regular $$G_\delta $$ -diagonal has cardinality at most $$2^\mathfrak {c}$$ . We also prove that every normal cellular-Lindelof first-countable space has cardinality at most continuum under $$2^{<\mathfrak {c}}=\mathfrak {c}$$ and that every normal cellular-Lindel…

A theoreticalab initiostudy on the H2NO + O3reaction

2003

The deviation of the NH2 pseudo-first-order decay Arrhenius plots of the NH2 + O3 reaction at high ozone pressures measured by experimentalists, has been attributed to the regeneration of NH2 radicals due to the subsequent reactions of the products of this reaction with ozone. Although these products have not yet been characterized experimentally, the radical H2NO has been postulated, because it can regenerate NH2 radicals through the reactions: H2NO + O3 NH2 + O2 and H2NO + O3 HNO + OH + O2. With the purpose of providing a reasonable explanation from a theoretical point of view to the kinetic observed behaviour of the NH2 + O3 system, we have carried ab initio electronic structure calculat…

Problems of coding stereo images in human memory

2010

This paper discusses the memorization and recall by man of a sequence of planar or stereoscopic images, including six frames that contain a planar strip (8×8 positions of the stimulus) or a volume strip (8×4×2 positions). At the recall stage, the subject chose between the stimulus and three distractors in each frame. It is shown that the times for recognition and recall are less for volume stimuli, while the percent of correct responses is greater for planar stimuli. For volume stimuli, the distribution of errors depends on the disparity between the target and the selected distractor. A model based on a heteroassociative neural network reproduces the error distribution for planar but not fo…

On vibrating thin membranes with mass concentrated near the boundary: an asymptotic analysis

2018

We consider the spectral problem \begin{equation*} \left\{\begin{array}{ll} -\Delta u_{\varepsilon}=\lambda(\varepsilon)\rho_{\varepsilon}u_{\varepsilon} & {\rm in}\ \Omega\\ \frac{\partial u_{\varepsilon}}{\partial\nu}=0 & {\rm on}\ \partial\Omega \end{array}\right. \end{equation*} in a smooth bounded domain $\Omega$ of $\mathbb R^2$. The factor $\rho_{\varepsilon}$ which appears in the first equation plays the role of a mass density and it is equal to a constant of order $\varepsilon^{-1}$ in an $\varepsilon$-neighborhood of the boundary and to a constant of order $\varepsilon$ in the rest of $\Omega$. We study the asymptotic behavior of the eigenvalues $\lambda(\varepsilon)$ and the eige…

Adaptive Mid-Term Representations for Robust Audio Event Classification

2018

Low-level audio features are commonly used in many audio analysis tasks, such as audio scene classification or acoustic event detection. Due to the variable length of audio signals, it is a common approach to create fixed-length feature vectors consisting of a set of statistics that summarize the temporal variability of such short-term features. To avoid the loss of temporal information, the audio event can be divided into a set of mid-term segments or texture windows. However, such an approach requires to estimate accurately the onset and offset times of the audio events in order to obtain a robust mid-term statistical description of their temporal evolution. This paper proposes the use of…