Wednesday, October 9, 2013
Postdoc available - institute of advanced study on a tripple geographical site: Strasbourg/Luxembourg University/Cardiff University
The goal of the post-doc is to extend the preliminary results which can be seen here: http://youtu.be/KqM7rh6sE8s and will appear shortly in the journal Medical Image Analysis
The candidate will be based in Strasbourg in the ICube laboratory http://icube.unistra.fr/en/
She/he will be collaborating intensively with the University of Luxembourg, where I am based and with Cardiff University, where I hold an adjunct professorship.
In Strasbourg, the collaboration will be with the ICube laboratory and with the SHACRA team led by Stéphane Cotin.
In Luxembourg, the collaboration will be with the other ERC Starting Grant-funded RealTcut Post-docs, in particular Dr. Jack Hale.
The successful candidate will have the chance to join a dynamic team of about 15 researchers at all level, and to contribute to the supervision of PhD students working in related areas.
There are possibilities to extend the contract beyond the 48 months through applications to the Fonds National de la Recherche du Luxembourg (http://www.fnr.lu/fr/AFR-PhD-Postdoc-Grants/Postdoc-Grants), or through the ERC Starting Grant (RealTcut).
The candidate MUST be an expert C++ programmer.
The candidate is expected to have demonstrated successful research in computational biomechanics, if possible at the interface between computer science, mathematics and mechanics.
The candidate should have proven experience in at least two of the following technical areas:
- coding iterative solvers and preconditioners on advanced architectures (GPUs, MPI, etc.)
- real-time simulation
- coding advanced mesh generators
- simulation of evolving discontinuities
- image to mesh transition in biomechanics
- domain decomposition methods in mechanics
AND have experience in at least one of the following general fields:
- algebraic model reduction for non-linear problems
- a posteriori error estimation for non-linear problems
- advanced numerical methods (extended finite element methods, mesh free methods, Cartesian grids)
- multiscale methods
- constitutive modelling of soft tissues
it would be a plus if the candidate was proficient in SOFA and had some command of either French or German.
The general research themes in the ERC project include:
- advanced discretisation (XFEM, meshless, immersed boundaries etc.)
- multiscale methods for fracture/cutting
- model reduction techniques (POD, reduced basis, morphing)
The successful candidate will join a dynamic team, based in three geographical locations (Luxembourg, Strasbourg, Cardiff), formed of a dozen PhD students and post-docs and will have ample opportunities to develop their career through doctoral supervision, grant applications, etc.
Please contact stephane . bordas @ alum. northwestern. edu
bordasS @ cardiff . ac. uk
for details.
Tuesday, August 6, 2013
CCP12 INSIST 1st UK Meshless Method Summer School
Announcement
Sunday, June 23, 2013
Sunday, June 2, 2013
Wednesday, May 15, 2013
Friday, May 10, 2013
Tuesday, May 7, 2013
Monday, May 6, 2013
Friday, April 26, 2013
MAFELAP 2013 presentation
http://people.brunel.ac.uk/~icsrsss/bicom/mafelap2013/
"Advances in extended finite element methods for fracture and heterogeneous materials"
This presentation will address recent advances in enriched numerical methods to simplify the treatment of evolving discontinuities in the field variables or their derivatives: cracks or material interfaces; and to treat geometrically intricate domains and their evolution.
The presentation will be composed of three parts:
(1) advances in numerical methods aiming at simplifying the treatment of complex geometries;
Two competing approaches coexist in the literature to simplify the solution of partial differential equations over domains of complex and/or evolving geometries. One focuses on streamlining the transition between computer aided design (CAD) data and the solution of problems over the corresponding domains. An example of this is isogeometric analysis (Hughes et al. 2005) where the geometry description and the approximation of the field variables are tied, thus enabling an exact treatment of the boundary as well as simplifying eventual geometric design iterations.
The second approach follows an orthogonal direction, where the geometry is uncoupled from the field variable discretisation, e.g. embedded boundary methods such as the structured extended finite element method of (Belytschko et al. 2003).
We will present results emanating from both lines of thought: isogeometric analysis of three-dimensional structures and embedded interfaces for complex geometries including sharp edges and vertices.
(2) advances in enriched formulations for evolving discontinuities such as cracks
The extended finite element method (XFEM) was introduced in (Belytschko and Black, 1999), with, as a basis, the partition of unity enrichment method of (Melenk and Babuška, 1996). The XFEM enables the simulation of evolving discontinuities without or with minimal remeshing.
We present recent developments in the area and focus on tackling difficulties associated with the control of the conditioning number of the system, the control of the error in quantities of interest, element distortion and blending errors between different partitions of unity.
(3) applications of those methods to problems in Silicon wafer manufacturing and brain surgery simulation.
Finally, as an application, we will present a simple method to grow several hundreds of cracks in two-dimensions in order to predict their growth and coalescence in brittle materials using the XFEM.
We will also present recent results permitting the simulation of cutting and contact during brain surgery simulation at 30 frames per second using an implicit time integration method and a hybrid, asynchronous CPU/GPU solver.
We finish the presentation by conclusions and propositions for future work.
Acknowledgements: Stéphane P.A. Bordas wishes to thank the organisers of MAFELAP for their kind invitation. He is grateful to the European Research Council for funding the research presented (ERC Stg grant agreement No. 279578: "RealTCut Towards real time multiscale simulation of cut- ting in non-linear materials with applications to surgical simulation and computer guided surgery").
Friday, March 29, 2013
Friday, March 22, 2013
Thursday, March 21, 2013
SIAM National Student Chapter Conference 2013
Subject: SIAM National Student Chapter Conference 2013
A reminder that Registration is now open for participation in the annual SIAM National Student Chapter Conference to take place in Warwick on the 10th of May 2013:The abstracts for the invited lectures are already available there and look really interesting!!Plenary Talks:
- Accuracy and Reproducibility of Numerical Computations, Nicholas J. Higham - University of Manchester
- Magnetic chains: from self-buckling to self-assembly, Alain Goriely - University of Oxford
- Phase transitions and computational tractability, Mark Jerrum - Queen Mary, University of London
Sponsor Talks:
- Implementing Algorithms: the link between academia and industry, Edvin Deadman, The Numerical Algorithms Group (NAG)
The deadline for submission of a title/abstract for a short talk (20min) or a poster is 19 April.
Tuesday, March 19, 2013
Applied Maths/Engineering Seminar - TODAY
Seminar today - Tuesday 19th March 2013 at 16:10 in M/2.06 (MATHS)Speaker: Prof Serafim Kalliadasis (Imperial).
Title: Recent progress on the moving contact line problem.
Abstract: The moving contact line problem is a long-standing and fundamental challenge in the field of fluid dynamics, occurring when one fluid replaces another as it moves along a solid surface. Moving contact lines occur in a vast range of applications, where an apparent paradox of motion of a fluid-fluid interface, yet static fluid velocity at the solid satisfying the no-slip boundary condition arises. In this talk we will review recent progress on the problem made by our group.
The motion of a contact line is examined, and comparisons drawn, for a variety of proposed models in the literature. We first scrutinise a number of models in the classic test-bed system of spreading of a thin two-dimensional droplet on a planar substrate, showing that slip, precursor film and interface formation models effectively reduce to the same spreading behaviour. This latter model, developed by Shikhmurzaev a few years ago, is a complex and somewhat controversial one, differentiating itself by accounting for a variation in surface layer quantities and having finite-time surface tension relaxation. Extensions to consider substrate heterogeneities in this prototype system for slip models are also considered, such as for surface roughness and fluctuations in wetting properties through chemical variability. Analysis of a solid-liquid-gas diffuse-interface model is then presented, with no-slip at the solid and where the fluid phase is specified by a continuous density field. We first obtain a wetting boundary condition on the solid that allows us to consider the motion without any additional physics, i.e. without density gradients at the wall away from the contact line associated with precursor films.
Careful examination of the asymptotic behaviour as the contact line is approached is then shown to resolve the singularities associated with the moving contact line problem. Various features of the model are scrutinised alongside extensions to incorporate slip, finite-time relaxation of the chemical potential, or a precursor film at the wall. But these are not necessary to resolve the moving contact line problem.
Tea/coffee will be available in the UCAS Room afterwards
Tuesday, March 5, 2013
Applied Maths/Engineering Workshop - TODAY
Subject: Applied Maths/Engineering Workshop - TODAY
Tuesday 5th March
16:10 Applied Mathematics/Engineering Research Workshop: Room M/2.06
Speaker: Maurice Blount (MATHS)
Title: The adhesion and desiccation of a sessile vesicle
Abstract:
Anhydrobiosis is a proposed method of preserving biological material through drying it rather than freezing it. To understand aspects of this process, I model the cell as a semi-permeable elastic membrane (a vesicle), and first apply a long-wave approximation to describe the drying process in regimes where the vesicle is strongly adhered to a substrate. The results of this simplified model are compared with those of boundary-integral simulations, and I analyse the latter to show how the process of vesicle adhesion depends strongly on the thin layer of fluid that is trapped between the vesicle and the substrate.
Monday, February 25, 2013
Applied Maths/Engineering Workshop
Subject: Applied Maths/Engineering Workshop
are:
26 February 16:10 Applied Maths/Engineering Workshop. Room S/0.38 ENGIN
Speaker: Sam Evans (ENGIN)
Title: Errors and Uncertainties in the Identification of Material Parameters Using nn Inverse FE Approach
Abstract
Soft materials exhibit complex nonlinear mechanical behaviour which is not easily amenable to mathematical modelling. Recently the availability of fast computers and medical imaging techniques has allowed considerable progress in this area, and there are many interesting applications including engineering design, animation and games and medical problems such as surgical planning and navigation.
A major difficulty is the measurement of material properties, which typically requires an "inverse finite element" approach in which a model of an experiment is adjusted to match the experiment in order to identify the material parameters. Often complex material models with many parameters are used, making this a very challenging problem with numerous uncertainties. Although it may be possible to find a set of parameters which matches the experiment reasonably well, it is very difficult to know whether these are the best parameters or what range of other values might be equally good. Typically there are very large uncertainties which are not well understood and cannot easily be quantified. The aim of this study was to develop methods to quantify these uncertainties and identify not just a plausible set of material parameters but also a confidence space, allowing meaningful statistical analysis of the results and a better understanding of the experimental design and optimisation process.
By using Gaussian process models to as emulators for a finite element model it is possible to quantify some of these uncertainties and hence to estimate the overall uncertainty in the identified parameters. Using a Condor network, multiple finite element models were generated and solved in parallel. Gaussian process models were then generated to predict the outputs, errors and variances of these models and hence to carry out a Monte Carlo simulation to quantify the confidence space for the identified parameters.
The actual solution of large deformation, nonlinear finite element models of soft materials is also an open mathematical problem. Current methods derived from linear finite element techniques are slow and unreliable and there is an urgent need for improved algorithms that can provide faster and more reliable convergence. The problem will be discussed in terms of optimisation methods and possible solution schemes using nonlinear conjugate gradient methods will be presented.
Seminar
>
> Details of this weeks workshop are:
>
> 26 February 16:10 Applied Maths/Engineering Workshop. *Room S/0.38 ENGIN*
>
> Speaker: Sam Evans (ENGIN)
>
> Title: Errors and Uncertainties in the Identification of Material
> Parameters Using nn Inverse FE Approach
>
>
> Abstract
> Soft materials exhibit complex nonlinear mechanical behaviour which is not
> easily amenable to mathematical modelling. Recently the availability of
> fast computers and medical imaging techniques has allowed considerable
> progress in this area, and there are many interesting applications
> including engineering design, animation and games and medical problems such
> as surgical planning and navigation.
> A major difficulty is the measurement of material properties, which
> typically requires an "inverse finite element" approach in which a model of
> an experiment is adjusted to match the experiment in order to identify the
> material parameters. Often complex material models with many parameters
> are used, making this a very challenging problem with numerous
> uncertainties. Although it may be possible to find a set of parameters
> which matches the experiment reasonably well, it is very difficult to know
> whether these are the best parameters or what range of other values might
> be equally good. Typically there are very large uncertainties which are
> not well understood and cannot easily be quantified. The aim of this study
> was to develop methods to quantify these uncertainties and identify not
> just a plausible set of material parameters but also a confidence space,
> allowing meaningful statistical analysis of the results and a better
> understanding of the experimental design and optimisation process.
> By using Gaussian process models to as emulators for a finite element model
> it is possible to quantify some of these uncertainties and hence to
> estimate the overall uncertainty in the identified parameters. Using a
> Condor network, multiple finite element models were generated and solved in
Thursday, February 21, 2013
Wednesday, February 13, 2013
Monday, February 11, 2013
Tuesday, February 5, 2013
Research Seminar in S/0.26 at 2.00pm
Professor ChangSi Peng from Soochow University, China will visit our school during 25th Jan. – 12th Feb.
he will make a research presentation on the topic 'Laser Interference Nano-Lithography: Research and application'
in room S026 from 2:00 to 3:00pm on the Tuesday, 5th February. Following are a brief introduction to Professor Peng and the
abstract of his presentation. You are cordially invited to attend the seminar.
Wednesday, January 30, 2013
Fwd: TODAY: IMAM Research Seminar at 12 noon (S/1.41)
You are invited to a research seminar
The Virtual Fields Method : a tool to extract materials constitutive parameters from full-field measurements
that will be given by Professor Fabrice Pierron (Engineering Sciences, University of Southampton)
Today at 12 noon in room S/1.41.
See an Abstract below.
Postgraduates and RAs are also warmly invited and encouraged to attend.
Regards
Feodor Borodich
The Virtual Fields Method : a tool to extract materials constitutive parameters from full-field measurementsAbstract:
Fabrice PIERRON
Engineering Sciences, University of Southampton,
The fast development and diffusion of full-field deformation measurement techniques (such as digital image correlation, speckle interferometry etc.) has opened new prospects in the identification of the mechanical behaviour of materials. The research group led by Professor Fabrice Pierron has been active in this area for more than 15 years. In particular, an original identification method dedicated to full-field measurements has been in the centre of most of the developments in the group. This technique is called the Virtual Fields Method (VFM, www.camfit.fr).
The presentation will provide an overview of a vast range of applications of this methodology (static, vibrations, high strain rate) on different types of materials (composites, damaged materials, metals, welds, polymers, wood, foams etc...) to enhance the capabilities of the VFM and provide tracks for the future.
Short bio:
Dr. Fabrice Pierron is currently Professor at the University of Southampton, UK. He graduated from ENSEM in Nancy, France, in 1989, and received his PhD from Lyon University, France, in 1994. He has held an Assistant Professor post at the Ecole des Mines de Saint-Etienne from 1994 to 1999, and was a Professor at Arts et Métiers ParisTech (Châlons-en-Champagne, France) before moving to his current position in Southampton in May 2012.
Prof. Pierron is an expert in mechanical testing of composite materials but has been focusing his research on the use of novel identification strategies based on full-field measurements and heterogeneous tests for the last fifteen years. In particular, he has been instrumental in the development of the Virtual Fields Method (www.camfit.fr). Prof. Pierron has published over 75 ISI referenced journal papers and co-authored about 200 conference communications. He is currently Editor-in-Chief of Strain (Wiley) and previously Associate Editor of Experimental Mechanics (Springer). He holds a Wolfson Research Merit Award from the Royal Society.
Saturday, January 26, 2013
Friday, January 25, 2013
Open-source codes released
http://sourceforge.net/projects/elemfregalerkin/
http://sourceforge.net/projects/igabem/
http://sourceforge.net/projects/cmcodes/
http://sourceforge.net/projects/xfem/
https://sites.google.com/site/permixproject/
these links will provide open source codes in MATLAB, C++, FORTRAN and C for
element-free galerkin mesh less methods
extended finite element methods (xfem)
multiscale-fracture based on xfem, domain decomposition, bridging scale, xbdm, and arlequin methods
boundary element methods
isogeometric analysis with finite elements
isogeometric analysis with boundary elements
enriched isogeometric analysis
The Virtual Fields Method : a tool to extract materials constitutive parameters from full-field measurements
A Research seminar of the Institute of Mechanics and Advanced Materials (IMAM)The Virtual Fields Method : a tool to extract materials constitutive parameters from full-field measurements
that will be given by Professor Fabrice Pierron (Engineering Sciences, University of Southampton)
on Wednesday 30 January at 12 noon in room S/1.41.The Virtual Fields Method : a tool to extract materials constitutive parameters from full-field measurementsFabrice PIERRON
Engineering Sciences, University of Southampton,
Abstract:
The fast development and diffusion of full-field deformation measurement techniques (such as digital image correlation, speckle interferometry etc.) has opened new prospects in the identification of the mechanical behaviour of materials. The research group led by Professor Fabrice Pierron has been active in this area for more than 15 years. In particular, an original identification method dedicated to full-field measurements has been in the centre of most of the developments in the group. This technique is called the Virtual Fields Method (VFM, www.camfit.fr).
The presentation will provide an overview of a vast range of applications of this methodology (static, vibrations, high strain rate) on different types of materials (composites, damaged materials, metals, welds, polymers, wood, foams etc...) to enhance the capabilities of the VFM and provide tracks for the future.
Short bio:
Dr. Fabrice Pierron is currently Professor at the University of Southampton, UK. He graduated from ENSEM in Nancy, France, in 1989, and received his PhD from Lyon University, France, in 1994. He has held an Assistant Professor post at the Ecole des Mines de Saint-Etienne from 1994 to 1999, and was a Professor at Arts et Métiers ParisTech (Châlons-en-Champagne, France) before moving to his current position in Southampton in May 2012.
Prof. Pierron is an expert in mechanical testing of composite materials but has been focusing his research on the use of novel identification strategies based on full-field measurements and heterogeneous tests for the last fifteen years. In particular, he has been instrumental in the development of the Virtual Fields Method (www.camfit.fr). Prof. Pierron has published over 75 ISI referenced journal papers and co-authored about 200 conference communications. He is currently Editor-in-Chief of Strain (Wiley) and previously Associate Editor of Experimental Mechanics (Springer). He holds a Wolfson Research Merit Award from the Royal Society.
Stéphane P.A. Bordas, Professor
Director, Institute of Mechanics & Advanced Materials (IMAM)
ERC Starting Grant Research Group Leader (RealTCut)
School of Engineering
Cardiff University, Queen's Buildings
The Parade, CARDIFF CF24 3AA, Wales, UK.
2013 CISM COURSE ON ISOGEOMETRIC ANALYSIS http://www.cism.it/courses/C1301/
OPEN SOURCE MULTISCALE FRACTURE CODE: https://sites.google.com/site/permixproject/features
OPEN SOURCE XFEM/MESHFREE/ISOGEOMETRIC ANALYSIS CODES: http://sourceforge.net/users/cmechanicsos
Tel +44 (0)29 20875941. Room number S/1.03.
RESEARCH METRICS:
http://www.researcherid.com/rid/A-1858-2009
http://scholar.google.com/citations?user=QKZBZ48AAAAJ&hl=en
http://www.engin.cf.ac.uk/whoswho/profile.asp?RecordNo=679
POSITIONS OPEN: http://imechanica.org/blog/700
POST DOCS AVAILABLE: http://www.cardiff.ac.uk/jobs/engin/research-assistants--research-associates-3-posts-4631.html
XFEM2011 ECCOMAS CONFERENCE http://www.xfem2011.com
Sur Ernest Renan: "le but de l'humanité est la constitution d'une conscience supérieure."
Funding for PhDs at Cardiff School of Engineering http://www.cardiff.ac.uk/engin/degreeprogrammes/research/fundingyourstudies/index.html
16:10 Applied Mathematics/Engineering Research Workshop Series: Room M/2.06
Speaker: Dr Lars Beex (ENGIN)
Title: Multiscale quasicontinuum modelling of fibrous materials
Tea/Coffee and mince pies afterwards in the UCAS Room.
There are some seminars scheduled later in the term (details to follow). We'll draw up
a programme of activities after this first workshop.