Search results for "Modeling"
showing 10 items of 4489 documents
Computing oscillatory solutions of the Euler system via đť’¦-convergence
2021
We develop a method to compute effectively the Young measures associated to sequences of numerical solutions of the compressible Euler system. Our approach is based on the concept of [Formula: see text]-convergence adapted to sequences of parameterized measures. The convergence is strong in space and time (a.e. pointwise or in certain [Formula: see text] spaces) whereas the measures converge narrowly or in the Wasserstein distance to the corresponding limit.
Numerical Algorithms Based on Characteristic Domain Decomposition for Obstacle Problems
1997
A new numerical solution algorithm for obstacle problems is proposed, where the characteristic domain decomposition into active and inactive subdomains separated by the free boundary is approximated by a Schwarz method. Such an approach gives an opportunity to apply fast linear system solvers to genuinely non-linear obstacle problems. Other solution algorithms, like projected relaxation methods and active set strategies, are compared to the new solution algorithm. Numerical experiments related to the elastoplastic torsion problem are included showing the efficiency of the new approach.
Computation of a few smallest eigenvalues of elliptic operators using fast elliptic solvers
2001
The computation of a few smallest eigenvalues of generalized algebraic eigenvalue problems is studied. The considered problems are obtained by discretizing self-adjoint second-order elliptic partial differential eigenvalue problems in two- or three-dimensional domains. The standard Lanczos algorithm with the complete orthogonalization is used to compute some eigenvalues of the inverted eigenvalue problem. Under suitable assumptions, the number of Lanczos iterations is shown to be independent of the problem size. The arising linear problems are solved using some standard fast elliptic solver. Numerical experiments demonstrate that the inverted problem is much easier to solve with the Lanczos…
Fractional-order poromechanics for a fully saturated biological tissue: Biomechanics of meniscus
2023
Biomechanics of biological fibrous tissues as the meniscus are strongly influenced by past histories of strains involving the so-called material hereditariness. In this paper, a three-axial model of linear hereditariness that makes use of fractional-order calculus is used to describe the constitutive behavior of the tissue. Fluid flow across meniscus' pores is modeled in this paper with Darcy relation yielding a novel model of fractional-order poromechanics, describing the evolution of the diffusion phenomenon in the meniscus. A numerical application involving an 1D confined compression test is reported to show the effect of the material hereditariness on the pressure drop evolution.
A Hardware and Secure Pseudorandom Generator for Constrained Devices
2018
Hardware security for an Internet of Things or cyber physical system drives the need for ubiquitous cryptography to different sensing infrastructures in these fields. In particular, generating strong cryptographic keys on such resource-constrained device depends on a lightweight and cryptographically secure random number generator. In this research work, we have introduced a new hardware chaos-based pseudorandom number generator, which is mainly based on the deletion of an Hamilton cycle within the $N$ -cube (or on the vectorial negation), plus one single permutation. We have rigorously proven the chaotic behavior and cryptographically secure property of the whole proposal: the mid-term eff…
Impulsive Tests on Historical Structures: The Dome of Teatro Massimo in Palermo
2016
Cultural heritage is the set of things, that having particular historical cultural and aesthetic are of public interest and constitute the wealth and civilization of a place and its people. Sharpen up methodologies aimed at safeguarding of monuments is crucial because the future may have in mind the historical past. Italy is a country that has invested heavily on its historical memory returned in large part by the historical building or the monuments. Furthermore, culture represents a fundamental indicator of the growth of the culture of a country. Consider a monitoring project of one of the most Impressive theater in the world, like “Teatro Massimo” in Palermo (Italy), means to add value t…
Towards a local approach to fatigue, for the calculation of structures, applied to continuous fibre reinforced composite materials and structures
2018
The original concept of mechanical fatigue was linked to the failure of structures and was treated at first within the framework of Fracture Mechanics. Models developed to explain this phenomenon must therefore be able to be applied to structures: changing the structure means changes to the model and its identification. It is therefore judicious to develop models capable of treating both the damage processes and also able to be used within a local framework: to this end a method based on Damage Mechanics seems appropriate. This approach has long been employed and requires only the identification of damage processes at the level of the RVE (Representative Volume Element) to be used for any s…
Influence of Teacher and Family Support on University Student Motivation and Engagement
2021
Although many studies endorse the notion that the way students perceive support influences their engagement, very few have explored the possible mediator role of intention to learn between these variables. The present work provides new evidence to the existing literature because it analyses the work of intention to learn (measured with expectancy–value beliefs and achievement goals) as a mediating motivational variable in the relation between university students’ external support (teacher and family) and their engagement. The Educational Situation Quality Model (MOCSE, its acronym in Spanish) has employed as a theoretical framework to perform this analysis. A sample of 267 Spanish universit…
Internal Structure and Dynamics of the Decamer D(ATGCAGTCAG) 2 In Li + -H 2 O Solution: A molecular Dynamics Simulation Study
2003
Molecular dynamics simulation of the decamer d(ATGCAGTCAG) 2 in aqueous solution, electroneutralized by Li + ions has been carried out. Emphasis is on the verification of the equilibrium conditions and the related structural and dynamical properties. Applicability of the kinetic part of Boltzmann's H function as a measure of thermodynamic equilibrium is tested. Overall structural stability has been confirmed by different RMSDs. Conformational and helicoidal parameters have been analyzed statistically and dynamically. Dynamical analysis reveals the existence of dynamical sub-states, which typically appear as abrupt changes from a mean level to another in the value of parameter. In statistica…
A comparison of two different formulations for Arc Routing Problems on Mixed graphs
2006
[EN] Arc routing problems on mixed graphs have been modelled in the literature either using just one variable per edge or associating to each edge two variables, each one representing its traversal in the corresponding direction. In this paper, and using the mixed general routing problem as an example, we compare theoretical and computationally both formulations as well as the lower bounds obtained from them using Linear Programming based methods. Extensive computational experiments, including some big and newly generated random instances, are presented.