Search results for "Numerical"
showing 10 items of 2002 documents
Revealing the pace of river landscape evolution during the Quaternary: recent developments in numerical dating methods
2016
During the last twenty years, several technical developments have considerably intensified the use of numerical dating methods for the Quaternary. The study of fluvial archives has greatly benefited from these enhancements, opening new dating horizons for a range of archives at distinct time scales and thereby providing new insights into previously unanswered questions. In this contribution, we separately present the state of the art of five numerical dating methods that are frequently used in the fluvial context: radiocarbon, Luminescence, Electron Spin Resonance (ESR), 230Th/U and terrestrial cosmogenic nuclides (TCN) dating. We focus on the major recent developments for each technique th…
Friction Stir Welding Of AA6082-T6 Sheets: Numerical Analysis And Experimental Tests
2004
3D numerical simulation of the Friction Stir Welding process is developed with the aim to highlight the process mechanics in terms of metal flux and temperature, strain and strain rate distributions. The numerical results have been validated though a set of experimental tests.
Analytic CCSD(T) second derivatives
1997
A general-purpose implementation of analytic CCSD(T) second derivatives is presented. Its applicability is demonstrated by calculations of vibration-rotation interaction constants for the astrophysically important molecule cyclopropenylidene (C3H2) in which the required cubic force constants have been determined by numerical differentiation of analytically evaluated second derivatives of the energy.
A numerical approach for the modelling of forming limits in hot incremental forming of AZ31 magnesium alloy
2021
AbstractMagnesium alloys, because of their good specific material strength, can be considered attractive by different industry fields, as the aerospace and the automotive one. However, their use is limited by the poor formability at room temperature. In this research, a numerical approach is proposed in order to determine an analytical expression of material formability in hot incremental forming processes. The numerical model was developed using the commercial software ABAQUS/Explicit. The Johnson-Cook material model was used, and the model was validated through experimental measurements carried out using the ARAMIS system. Different geometries were considered with temperature varying in a…
A novel One Domain Approach for free fluid-porous medium transport simulation. Preliminary results
2022
We present a new numerical solver for free-fluid flowing over and inside a porous medium. It is based over a macroscopic approach and one fictitious medium is assumed inside the domain, according to the One Domain Approach. Preliminary results are shown and compared with the ones provided by the well-known DuMux solver which applies a two Domain Approach.
Model of a Constructive Fuctional Optimization of the Cardan Cross
2015
This paper aims to establish an optimization model using the Ansys program, and taking into account the specific constraints depending on the functional role of the specific area. We present certain calculation parameters applied to the cardanic transmission of the Dacia, this cardanic transmission being considered an optimization model. The entire cardanic transmission was analyzed, resulting that the cardan crosses are parts which are strained the most, and that is why it will be here that the optimization will be focused, in terms of minimizing the Von Mises stress.
On the proper homotopy invariance of the Tucker property
2006
A non-compact polyhedron P is Tucker if, for any compact subset K ⊂ P, the fundamental group π1(P − K) is finitely generated. The main result of this note is that a manifold which is proper homotopy equivalent to a Tucker polyhedron is Tucker. We use Poenaru’s theory of the equivalence relations forced by the singularities of a non-degenerate simplicial map.
Comparison of Internal Clustering Validation Indices for Prototype-Based Clustering
2017
Clustering is an unsupervised machine learning and pattern recognition method. In general, in addition to revealing hidden groups of similar observations and clusters, their number needs to be determined. Internal clustering validation indices estimate this number without any external information. The purpose of this article is to evaluate, empirically, characteristics of a representative set of internal clustering validation indices with many datasets. The prototype-based clustering framework includes multiple, classical and robust, statistical estimates of cluster location so that the overall setting of the paper is novel. General observations on the quality of validation indices and on t…
Tools for studying water vapor at high temperatures
2014
1. Kinetics and Oxidation Mechanisms 1.1 Experimental Devices that Produce Water Vapor1.2 Using the Jump Method to Understand Oxidation Mechanisms and Kinetics1.3 Detection of Breakaway Oxidation with Acoustic Emission during Thermal Oxide Scale Growth 1.4 Stress Analysis during and after Oxidation 2. Characterization 2.1 Use and Potential of Environmental SEM (ESEM) in High-Temperature Oxidation and Corrosion Studies in Wet Air 2.2 In Situ X-Ray Diffraction for Water Vapor Analyses2.3 Use of Synchrotron Beam for Evaluating the Influence of Water Vapor on the Corrosion of Metallic Materials 2.4 Raman Spectrometry2.5 In Situ Steam Oxidation Chamber Coupled to XPS 2.6 Hydrogen Profiling in Ox…
Direct numerical simulations of creeping to early turbulent flow in unbaffled and baffled stirred tanks
2018
Abstract It has been known for a long time that the fluid flow and several global quantities, such as the power and pumping numbers, are about the same in baffled and unbaffled mechanically stirred vessels at low Reynolds numbers, but bifurcate at some intermediate Re and take drastically different values in fully turbulent flow. However, several details are not yet completely understood, notably concerning the relation of this bifurcation with the flow features and the transition to turbulence. In order to shed light on these issues, computational fluid dynamics was employed to predict the flow field in two vessels stirred by a six-bladed Rushton turbine at Reynolds numbers from 0.2 to 600…