Formulaçao de um elemento finito de cabo incorporando o efeito do atrito (Elemento de cabos escorregando)

O trabalho apresenta a formulacáo geometricamente exata e a implementaçao computacional de um elemento finito de cabo que permite o escorregamento em presenca de atrito. O novo elemento fornece procedimentos naturais para simular o processo de montagem e a resposta aos carregamentos de estruturas de cabos em geral, além de ter campos promissores de aplicaçáo no modelamento de estruturas de concreto protendido e no estudo de oscilaçoes auto-excitáveis. Resultados de exemplos elementares sáo discutidos.Peer Reviewe

Formulaçao de um elemento finito de cabo incorporando o efeito do atrito (Elemento de cabos escorregando)

O trabalho apresenta a formulacáo geometricamente exata e a implementaçao computacional de um elemento finito de cabo que permite o escorregamento em presenca de atrito. O novo elemento fornece procedimentos naturais para simular o processo de montagem e a resposta aos carregamentos de estruturas de cabos em geral, além de ter campos promissores de aplicaçáo no modelamento de estruturas de concreto protendido e no estudo de oscilaçoes auto-excitáveis. Resultados de exemplos elementares sáo discutidos.Peer Reviewe

Direct area minimization through dynamic relaxation

Minimal surfaces, characterized by the property of a minimal area within a fixed boundary, offer an interesting design option for membrane structures, since they are uniquely defined and provide economy of material and more regular fabric patterns. Analytical solution for the non-linear equation governing area minimization may be rather difficult for complex boundaries, leaving numerical solution as the only general way to tackle with the problem. In this paper we show that the dynamic relaxation method offers an interesting alternative to solve the area minimization problem, first interpreted as a nonlinear equilibrium problem, then replaced by a pseudo-dynamic analysis, where fictitious masses and damping matrices are arbitrarily chosen to control the stability of the time integration process

Implementation of a simple wrinkling model into argyris’ membrane finite element

This paper presents the implementation of a simple wrinkling/slackening model into the classical Argyris membrane element, comparing the solution performance by Newton’s iterations, using either the tangent stiffness matrix (numerically evaluated through a finite-difference approximation), or a secant stiffness matrix (obtained through the modification of the elasticity matrix, according to a projection technique which decompose deformations into elastic and wrinkle components)

Quantum phase transitions in one-dimensional nanostructures: a comparison between DFT and DMRG methodologies

In the realm of quantum chemistry, the accurate prediction of electronic structure and properties of nanostructures remains a formidable challenge. Density Functional Theory (DFT) and Density Matrix Renormalization Group (DMRG) have emerged as two powerful computational methods for addressing electronic correlation effects in diverse molecular systems. We compare ground-state energies ($e_0$), density profiles ($n$) and average entanglement entropies ($\bar S$) in metals, insulators and at the transition from metal to insulator, in homogeneous, superlattices and harmonically confined chains described by the fermionic one-dimensional Hubbard model. While for the homogeneous systems there is a clear hierarchy between the deviations, $D\%(\bar S)<D\%(e_0)< \bar D\%(n)$, and all the deviations decrease with the chain size; for superlattices and harmonical confinement the relation among the deviations is less trivial and strongly dependent on the superlattice structure and the confinement strength considered. For the superlattices, in general increasing the number of impurities in the unit cell represents less precision on the DFT calculations. For the confined chains, DFT performs better for metallic phases, while the highest deviations appear for the Mott and band-insulator phases. This work provides a comprehensive comparative analysis of these methodologies, shedding light on their respective strengths, limitations, and applications

Linear entropy fails to predict entanglement behavior in low-density fermionic systems

Entanglement is considered a fundamental ingredient for quantum technologies and condensed matter systems are among the good candidates for quantum devices. For bipartite pure states the von Neumann entropy is a proper measure of entanglement, while the linear entropy, associated to the mixedness of the reduced density matrices, is a simpler quantity to be obtained and is considered to be qualitatively equivalent to the von Neumann. Here we investigate both linear and von Neumann entropies for quantifying entanglement in homogeneous, superlattice and disordered Hubbard chains. We find regimes of parameters for which the linear entropy fails in reproducing the qualitative behavior of the von Neumann entropy. This then may lead to incorrect predictions i) of maximum and minimum entanglement states and ii) of quantum phase transitions

Nutritional quality and yield of onion as affected by different application methods and doses of humic substances

Fertilization with humic substances (HS) has been proposed as target tool to improve crop production within a sustainable agriculture framework. The dose and application method are two factors that can influence the effect of HS on nutrient composition and productivity of onion. Therefore, our main objective was to assess the effect of each of the abovementioned factors, separately or interacting, on the quality and productivity of onion bulbs in a field test. The experimental design was completely randomized in a factorial 2 × 3, with two methods of application of HS and three different doses. The combined application method, immersion together with foliar pulverization, showed highest improvement of biomass and nutritional content of bulbs. However, while the intermediate dose of HS exerted greater increases on onion yield, productivity, carbohydrates and proteins levels in bulbs, mineral nutrient accumulation resulted especially when highest doses of HS were added. From a nutritional point of view, higher sweetness (from 113 to 149 mg g−1 of soluble sugars in dry matter) and an improved P, K and Mg content of bulbs (4.00, 11.65 and 3.18 g kg−1, respectively) in response to HS addition has been ascribed.Marcelle M. Bettoni received a grant from ‘Los CAPES y Coordenação do Programa de Pós-graduação em Agronomia–Produção Vegetal’ from the Brazilian Government