Search results for "WTO"
showing 10 items of 163 documents
Elastohydrodynamic Collision of Two Spheres Allowing Slip on Their Surfaces.
2000
Our goal is to study theoretically the effect of deformation on the collision of two solid spheres allowing slip on their surfaces. The deformed shape of the solid surface is determined via an asymptotic technique assuming that deformation is small compared with the separation between the surfaces. It has previously been shown that the slippage makes collision possible even without any surface attractive force. Here we demonstrate that even a small amount of deformation can preclude spheres from coagulation. Copyright 2000 Academic Press.
A Study on Engineering Freshman Conceptual Understanding of Newtonian Mechanics
2021
Force concept inventory is a multiple-choice questionnaire commonly used to assess students’ conceptual understanding of Newtonian mechanics. We here show that a cluster analysis method can be used to study student answers to the force concept inventory to investigate their understanding of Newtonian mechanics and provide new insights into the use of the force concept inventory. We identi- fied groups of students characterized by similar correct answers as well as by non- correct answers to the questionnaire, whose analysis allowed us to highlight student misconceptions/non-normative conceptions. Such an analysis of student answers gave us insights into the relationships between the student…
Deuring’s mass formula of a Mumford family
2015
We study the Newton polygon jumping locus of a Mumford family in char p p . Our main result says that, under a mild assumption on p p , the jumping locus consists of only supersingular points and its cardinality is equal to ( p r − 1 ) ( g − 1 ) (p^r-1)(g-1) , where r r is the degree of the defining field of the base curve of a Mumford family in char p p and g g is the genus of the curve. The underlying technique is the p p -adic Hodge theory.
Molecular-dynamics study of copper with defects under strain
1998
Mechanical properties of copper with various types of defects have been studied with the molecular-dynamics method and the effective-medium theory potential both at room temperature and near zero temperature. The loading has been introduced as constant rate straining and the dynamics of the process region of fracture is purely Newtonian. With the model three types of defects were studied: point defects, grain boundary, and an initial void serving as a crack seed. Point defects were seen to decrease the system strength in terms of fracture stress, fracture strain, and elastic modulus. Due to random microstructure, highly disordered systems turned out to be isotropic, which on the other hand …
Kinematic splitting algorithm for fluid–structure interaction in hemodynamics
2013
Abstract In this paper we study a kinematic splitting algorithm for fluid–structure interaction problems. This algorithm belongs to the class of loosely-coupled fluid–structure interaction schemes. We will present stability analysis for a coupled problem of non-Newtonian shear-dependent fluids in moving domains with viscoelastic boundaries. Fluid flow is described by the conservation laws with nonlinearities in convective and diffusive terms. For simplicity of presentation the structure is modelled by the generalized string equation, but the results presented in the paper may be generalized to more complex structure models. The arbitrary Lagrangian–Eulerian approach is used in order to take…
Deficiencias epistemológicas en la enseñanza habitual de los conceptos de campo y potencial eléctrico
1997
This article intends to analyse up to what extent the scarce learning produced when introducing the basic concepts on electrostatics is due to deficiencies and inadequacies in its routine teaching. So, on the one hand, we analyse what have been the principal epistemological leaps forward in the making of electricity as a science. On the other hand, we analyse Physics books and the teachers’ opinions.
Newtonian and Non-Newtonian Elements in Hume
2016
For the last forty years, Hume's Newtonianism has been a debated topic in Hume scholarship. The crux of the matter can be formulated by the following question: Is Hume a Newtonian philosopher? Debates concerning this question have produced two lines of interpretation. I shall call them ‘traditional’ and ‘critical’ interpretations. The traditional interpretation asserts that there are many Newtonian elements in Hume, whereas the critical interpretation seriously questions this.In this article, I consider the main points made by both lines of interpretations and offer further arguments that contribute to this debate. I shall first argue, in favor of the traditional interpretation, that Hume i…
Quasi-Newton approach to nonnegative image restorations
2000
Abstract Image restoration, or deblurring, is the process of attempting to correct for degradation in a recorded image. Typically the blurring system is assumed to be linear and spatially invariant, and fast Fourier transform (FFT) based schemes result in efficient computational image restoration methods. However, real images have properties that cannot always be handled by linear methods. In particular, an image consists of positive light intensities, and thus a nonnegativity constraint should be enforced. This constraint and other ways of incorporating a priori information have been suggested in various applications, and can lead to substantial improvements in the reconstructions. Neverth…
The double cone: a mechanical paradox or a geometrical constraint?
2011
In the framework of the Italian National Plan ‘Lauree Scientifiche’ (PLS) in collaboration with secondary schools, we have investigated the mechanical paradox of the double cone. We have calculated the geometric condition for obtaining an upward movement. Based on this result, we have built a mechanical model with a double cone made of aluminum and a couple of wooden rails.
Tests of General Relativity with GW170817
2019
The recent discovery by Advanced LIGO and Advanced Virgo of a gravitational wave signal from a binary neutron star inspiral has enabled tests of general relativity (GR) with this new type of source. This source, for the first time, permits tests of strong-field dynamics of compact binaries in presence of matter. In this paper, we place constraints on the dipole radiation and possible deviations from GR in the post-Newtonian coefficients that govern the inspiral regime. Bounds on modified dispersion of gravitational waves are obtained; in combination with information from the observed electromagnetic counterpart we can also constrain effects due to large extra dimensions. Finally, the polari…