Search results for "equation"

Nonlinear finite element analysis of no-tension masonry structures

1995

A numerical approach for structural analysis of masonry walls in plane stress conditions is presented. The assumption of a perfectly no-tension material (NTM) constitutive model, whose relevant equations are in the form of classical rate-independent associated flow laws of elastoplastic material, allows one to adopt numerical procedures commonly used in computational plasticity. An accuracy analysis on the integration algorithm employed in the solution of constitutive relations has been carried out. The results obtained for some relevant case-studies and their comparison with data, available in the literature show the effectiveness of the proposed method.

A marching in space and time solver for the complete 2D shallow water equations. Application to real test cases.

2006

Extracting string motif bases for quorum higher than two

2012

Bases of generators of motifs consisting of strings in which some positions can be occupied by a don’t care provide a useful conceptual tool for their description and a way to reduce the time and space involved in the discovery process. In the last few years, a few algorithms have been proposed for the extraction of a basis, building in large part on combinatorial properties of strings and their autocorrelations. Currently, the most efficient techniques for binary alphabets and quorum q = 2 require time quadratic in the length of the host string. The present paper explores properties of motif bases for quorum q ≥ 2, both with binary and general alphabets, by also showing that important resu…

Electronic properties of graphene: A learning path for undergraduate students

2016

The purpose of this work is to present a learning path aimed at deepening student understanding of the fundamental concepts underlying the electronic properties of new materials, graphene in particular. To achieve this task, we propose a five-week long workshop where students may be introduced to fundamental concepts of advanced physics, rarely used in learning paths, such as the symmetry properties of the crystal lattice, the group theory , the features of the free electron wave functions and energy levels, the relativistic Dirac equation. Particular emphasis is given to the manner of introducing these concepts, since an essential knowledge of solid state physics, quantum physics and relat…

More Power through Symbolic Computation: Extending Stata by using the Maxima Computer algebra system

2015

Maxima is a free and open-source computer algebra system that can perform symbolic computations such as solving equations, determining derivatives of functions, obtaining Taylor series, and manipulating algebraic expressions. In this article, I present the Maxima Bridge System, which is a collection of software programs that allows Stata to interface with Maxima so that Maxima can be used for symbolic computation to transfer data from Stata to Maxima and to retrieve results from Maxima. The cooperation between Stata and Maxima provides an environment for statistical analysis in which symbolic computation can be easily used together with all the facilities supplied by Stata. In this environ…

Analogical Modeling and Numerical Simulation for Sintering Phenomena

2013

In this paper the authors propose an approach for analogical modeling and numerical simulation of the phenomena of sintering, taking into account different cases depending on the type of energy used in the process of aggregation and the nature of the material powder, using a software which simulates the propagation and the control of the temperature. Many physical phenomena encountered in science and engineering can be described mathematically through partial differential equations (PDE) and ordinary differential equations (ODE) such as propagation phenomena, engineering applications, hydrotechnics, chemistry, pollution a.s.o. There may be situations when the exact establish of the analytic…

Multiple Crack Localization and Debonding Mechanisms for Thin Thermal Coating Films

2020

Experimental tests, carried out on small scale alloy specimens covered on one side with a thin thermal coating, have shown complex failure mechanisms. The failure mechanisms observed are due to the competition between two fracture mechanisms. The two mechanisms are: (i) Vertical tensile coating surface cracks and (ii) debonding shear decohesion mechanisms along the interface between the coating and the substrate. The present paper analyzes the mechanical problem of the nonlinear behavior thin film on a stiff substrate adopting a computational approach. Namely, incremental 2D nonlinear finite element simulations. The stiff superalloy substrate is modeled as a thermo-elastic material. The coa…

Estimation of Nucleation Barriers from Simulations of Crystal Nuclei Surrounded by Fluid in Equilibrium

2016

Nucleation rates for homogeneous nucleation are commonly estimated in terms of an Arrhenius law involving the nucleation barrier, written in terms of a competition of the contribution in surface free energy of the nucleus and the free energy gain proportional to the nucleus volume. For crystal nuclei this “classical nucleation theory” is hampered by the problem that the nucleus in general is non spherical, since the interfacial excess free energy depends on the orientation of the interface relative to the crystal axes. This problem can be avoided by analyzing the equilibrium of a crystal nucleus surrounded by fluid in a small simulation box in thermal equilibrium. Estimating the fluid press…

A Unified Perspective on the Dynamics of Axisymmetric Hurricanes and Monsoons

2006

Abstract This paper provides a unified perspective on the dynamics of hurricane- and monsoonlike vortices by identifying them as specific limiting cases of a more general flow system. This more general system is defined as stationary axisymmetric balanced flow of a stably stratified non-Boussinesq atmosphere on the f plane. The model is based on the primitive equations assuming gradient wind balance in the radial momentum equation. The flow is forced by heating in the vortex center, which is implemented as relaxation toward a specified equilibrium temperature Te. The flow is dissipated through surface friction, and it is assumed to be almost inviscid in the interior. The heating is assumed …

Coexistence of active Brownian disks: van der Waals theory and analytical results

2020

At thermal equilibrium, intensive quantities like temperature and pressure have to be uniform throughout the system, restricting inhomogeneous systems composed of different phases. The paradigmatic example is the coexistence of vapor and liquid, a state that can also be observed for active Brownian particles steadily driven away from equilibrium. Recently, a strategy has been proposed that allows to predict phase equilibria of active particles [Solon et al., Phys. Rev. E 97, 020602(R) (2018)2470-004510.1103/PhysRevE.97.020602]. Here we elaborate on this strategy and formulate it in the framework of a van der Waals theory for active disks. For a given equation of state, we derive the effecti…