Search results for " Numerical Methods"
showing 6 items of 26 documents
Bio-electromagnetic Numerical Modeling for Health Diagnostics
On the history of torsional stress concentrations in shafts: From electrical analogies to numerical methods
2014
This article proposes a retrospective on experimental and numerical methods developed throughout the past century to solve the torsion problem in shafts, with particular emphasis on the determination of shear stress concentration factors in discontinuities of typical use in shaft design. This article, in particular, presents the theory and related solutions distinguishing between two classes of geometries: shafts with constant cross section and axisymmetric shafts with variable diameter. Emphasis is given to approaches based on physical analog methods and, in particular, those based on electrical analogies proposed since about 1925. Experimental methods based on structural physical models …
A New Approach to the Modeling of Anisotropic Media with the Transmission Line Matrix Method
2021
A reformulation of the Transmission Line Matrix (TLM) method is presented to model non-dispersive anisotropic media. Two TLM-based solutions to solve this problem can already be found in the literature, each one with an interesting feature. One can be considered a more conceptual approach, close to the TLM fundamentals, which identifies each TLM in Maxwell’s equations with a specific line. But this simplicity is achieved at the expense of an increase in the memory storage requirements of a general situation. The second existing solution is a more powerful and general formulation that avoids this increase in memory storage. However, it is based on signal processing techniques and considerabl…
New Indicators of Approximation Errors for Problems in Continuum Mechanics
2010
In this paper we present a new error indicator for approximate solutions of elliptic problems. We discuss error indication with the paradigm of the diffusion problem, however the techniques are easily adaptable to more complicated elliptic problems, for example to linear elasticity, viscous flow models and electromagnetic models. The proposed indicator does not contain mesh dependent constants and it admits parallelization. nonPeerReviewed
Global sensitivity analysis in environmental water quality modelling: Where do we stand?
2014
Global sensitivity analysis (GSA) is a valuable tool to support the use of mathematical models for environmental systems. During the last years the water quality modelling field has embraced the use of GSA. Environmental water quality modellers have tried to transfer the knowledge and experience acquired in other disciplines. The main objective of this paper is to provide an informed problem statement of the issues surrounding GSA applications in the environmental water quality modelling field. Specifically, this paper aims at identifying, for each GSA method, the potential use, the critical issues to be solved and the limits identified in a comprehensive literature review. The paper shows …
Inserimento di restringimenti e ponti in un modello diffusivo 2D di acque basse
2010
Gli effetti su una corrente, causati dalle pile di un ponte, o più in generale da strutture che riducono la sezione trasversale dell’alveo, risultano di particolare interesse per le variazioni idrometriche che comportano alla corrente stessa. Nonostante i numerosi studi teorici e sperimentali di letteratura, l’attuale modellistica numerica diffusiva non integra la presenza di tali manufatti nelle proprie tecniche risolutive. Nella presente memoria viene presentata la metodologia implementata nel modello diffusivo bidimensionale FLOW2D per la valutazione del rigurgito provocato da restringimenti della sezione trasversale, nonché dalla presenza delle campate. I profili di rigurgito ottenuti c…