Braiding simulation for RTM preforms

Braiding is a manufacturing process that is increasingly being used to manufacture pre-forms for Resin Transfer Moulding. A fast simulation method is presented for the prediction of the fibre distribution on complex braided parts and complex kinetic situations (e.g. changes in velocity, orientation). The implementation is suited for triangular surface representations as generated by many CAD software packages in use. Experimental results are presented to validate the model predictions, showing an acceptable correlation with the data predicted by the simulation method. The guide ring dimensions and spacing appear to have a significant effect on the accuracy of the predicted fibre orientations

Finite element and automatic remeshing methods for the simulation of complex blow molded polymer components

International audienceThis paper presents a three dimensional finite element model of the extrusion blow molding process. The code Tform3 has the following characteristics: membrane formulation, linear triangle elements, updated Lagrangian implicit formulation, viscoelastic differential constitutive equations. The paper presents a brief recall of the formulation and then addresses three key issues of the simulation: automatic identification of constitutive equation parameters, automatic remeshing, coupling between gas pressure and inflation. An example of application to the extrusion blow molding of a bottle is presented

Algunas reflexiones acerca de la modelación y la formación matemática en el nivel superior

En las últimas tres décadas la modelación en Educación Matemática viene consolidándose como un dominio de investigación que se preocupa por la formación matemática de los estudiantes en los distintos niveles de escolaridad. El presente artículo recoge algunas reflexiones, experiencias e investigación que sus autores han desarrollado cuando indagan por la modelación matemática en la formación matemática en el nivel universitario. Para ello, se harán explícitas algunas necesidades, dimensiones y tipos de contextos, situaciones o fenómenos que pueden generar procesos de modelación acordes con los requerimientos que emergen de los programas de formación de algunos profesionales. Finalmente se presentan algunos desafíos para futuras investigaciones

Capture d'interface et application au procédé d'injection assistée eau

http://hdl.handle.net/2042/16392International audienceNous proposons une amélioration des techniques de capture d'interfaces, pour la simulation d'écoulements multiphasiques, en utilisant une méthode de h-adaptation de maillage. Une technique d'adaptation de maillage anisotrope basée sur les variations de gradients de la fonction level-set permet de capturer les discontinuités des paramètres physiques qui caractérisent les écoulements fortement hétérogènes. Cette méthode permet l'observation précise de l'évolution des différentes phases (eau/ polymère liquide eau/ polymère solide) ainsi que leurs interactions. Une application directe de cette amélioration est la simulation des problèmes multiphasiques complexes intervenant dans le procédé de fabrication de pièces creuses tel que l'injection assistée eau = We propose an improvement of interface capturing techniques by using an h-adaptation technique to improve computation of the multiphase flows. An anisotropic mesh adaptation technique based on variations of the level-set function allows a better capture of the discontinuities of the physical parameters that characterize the strongly heterogeneous flows. This method allows an accurate observation of the evolution of the various phases (water/liquid polymer, water solid polymer) as well as their interactions. A direct application of this improvement is the simulation of complex multiphase problems involved in the manufacturing processes of hollow parts such as the water assisted injection process

Un Modelo de Curso Integrado de Cálculo en una Variable.

El reto del Espacio Europeo de Educación Superior, que pretende unificar los estudios de los países miembros de la Unión Europea, ha puesto de manifiesto la posibilidad de usarlas técnicas de enseñanza no presencial como un canal más de transmisión del conocimiento para ser usado, en mayor o menor medida, junto con la enseñanza “más tradicional”. Ello nos permite diseñar un curso de Cálculo que aglutine los aspectos tradicionales (clases magistrales y de problemas) de la enseñanza de las matemáticas con las nuevas tecnologías (uso de paquetes de Cálculo Simbólico, webs interactivas, libros electrónicos, applets, etc.). Esto nos permitirá por un lado profundizar en determinados conceptos matemáticos y por otro la resolución de problemas “reales” y no problemas docentes y preparados, que son los únicos que pueden resolverse por los métodos tradicionales

Estimation of the neuromuscular fatigue threshold from an incremental cycling test using 1-minute exercise periods

The objectives of this study were: 1) to evaluate the method used for estimating the neuromuscular fatigue threshold from surface electromyographic amplitude (the PWCFT test) during a single incremental cycling workout using 1-minute exercise periods, and 2) to investigate the possible associations between PWCFT and metabolic (onset of blood lactate accumulation [OBLA]) and ventilatory (ventilatory threshold [VT] and respiratory compensation point [RCP]) variables.Sixteen cyclists performed incremental cycle ergometer rides to exhaustion with bipolar surface sEMG signals recorded from the vastus lateralis. Subsequently, participants performed one constant-workload exercise test at 100% of their PWCFT.During the incremental test, the power output at PWCFT was not correlated with that of OBLA (P>0.05), but it was positively correlated with those of VT and RCP (P0.05). The average duration of the constant-workload exercise was 8-9 minutes.The application of the PWCFT method using 1-min exercise periods could lead to overestimation of the neuromuscular fatigue threshold most likely because this stage duration allows insufficient time for the sEMG response to manifest

A novel R-package graphic user interface for the analysis of metabonomic profiles

Background Analysis of the plethora of metabolites found in the NMR spectra of biological fluids or tissues requires data complexity to be simplified. We present a graphical user interface (GUI) for NMR-based metabonomic analysis. The "Metabonomic Package" has been developed for metabonomics research as open-source software and uses the R statistical libraries. /Results The package offers the following options: Raw 1-dimensional spectra processing: phase, baseline correction and normalization. Importing processed spectra. Including/excluding spectral ranges, optional binning and bucketing, detection and alignment of peaks. Sorting of metabolites based on their ability to discriminate, metabolite selection, and outlier identification. Multivariate unsupervised analysis: principal components analysis (PCA). Multivariate supervised analysis: partial least squares (PLS), linear discriminant analysis (LDA), k-nearest neighbor classification. Neural networks. Visualization and overlapping of spectra. Plot values of the chemical shift position for different samples. Furthermore, the "Metabonomic" GUI includes a console to enable other kinds of analyses and to take advantage of all R statistical tools. /Conclusion We made complex multivariate analysis user-friendly for both experienced and novice users, which could help to expand the use of NMR-based metabonomics

Una caja informática de herramientas matemáticas

Se presenta en este trabajo una propuesta de actividad para un modelo de aprendizaje basado en competencias y con apoyo de herramientas informáticas. Se sugiere que el estudiante diseñe y elabore una “caja de herramientas” con la implementación, en un sistema informático, de algoritmos matemáticos elementales, que podrá utilizar posteriormente en la resolución de problemas tanto de matemáticas como de otras asignaturas. Como ejemplo se propone una caja que contiene herramientas relacionadas con aspectos de la geometría del plano estudiados en primer curso de Bachillerat