Spotlight on Young Researchers: Hussein Rappel


Hussein Rappel uses a mathematical learning approach to try to predict and simulate physical phenomena. The Iranian national came to Luxembourg in 2014 to join the team of Prof Stephane Bordas at the University of Luxembourg, where he is now in the 3rd year of his PhD in Computational Science – and sees great potential in Luxembourg as a research destination.

Hussein Rappel has a thirst for learning new things, and in research has found the ideal job for a curious, knowledge-hungry computer scientist. Since 2014, Hussein has been working with Prof Stephane Bordas, a renowned computational science researcher at the University of Luxembourg. ‘Computational science’ is a broad term nowadays, so what exactly does Hussein do for his PhD work?

Simulating physical phenomena

“We try to simulate physical phenomena (e.g. fracture, deformation and etc.), using mathematics and computer programming.

“In my research I am trying to use a mathematical learning approach called ‘Bayesian inference’ to identify the parameters for the material behaviour laws. The approach is very similar to what we do in our regular life to learn about an event and predict the next step. As an example you can imagine yourself driving your car, for any action that you are going to take for the next step you combine the current state information (the car speed, its position etc.) with the information from your surroundings ( such as the other cars, road situation…) and then you make your decision.

“This is almost what I do in my research by combing the measurements, the information that I already have and my physical model I identify the parameters for governing physical laws.”

In terms of what this looks like on in practice, Hussein explains that apart from reading up on the latest findings in his field and developing the mathematical models and codes needed for the simulation, discussing his findings and progress with his supervisors Dr Lars Beex and Prof. Stephane Bordas is a significant part of his regular activities.

Learning how to do original research in an up-and-coming research location

Being just over halfway through his PhD and thus still at the beginning of his research career, Hussein’s main goal as a researcher at the moment is mainly to learn how to do original research independently and publish the associated results – he adds: “Furthermore I would like to improve my skills by learning to write research proposals which would let me to convert my ideas from a simple idea to a research project.”

Hussein relocated from Iran to Luxembourg for his PhD, which he explains was more due to the chance to work PhD supervisor Stephane Bordas, (who himself came to Luxembourg a few years ago with his then newly-awarded ERC grant), than due to Luxembourg itself. As Hussein points out, however, the University of Luxembourg is slowly but surely building a reputation for itself:

“Considering the condition in Luxembourg and available resources I believe the country is going in the right direction and has great potential to become a very popular destination for researchers from various countries in the world.

“The University of Luxembourg is quite young but it gets recognised every year more than the previous year as it is a research-oriented university. Furthermore the possibility of creating various research centres in the university framework can help it to get even more research-oriented and as result more recognised.

“As an example you can consider creation of the Centre of Excellence in Scientific Computing which can help to do lots of interdisciplinary projects. These research projects can be in fields of finance, engineering, physics and so on.”

“This shows a schematic of Bayesian inference for parameter identification in Biomechanics. The figure in general shows how the Bayesian updating approach works for a parameter identification problem.”

“This figure shows the Bayesian inference prediction for the elasticity constant (Young’s modulus) after having one observation. As it is shown, the inference output is a probability density function which shows degree of our knowledge about the parameter of interest.”

“This shows the Bayesian approach output after four updates, or in other words, after having four measurements. One can see that as the number of our measurements increases the uncertainty decreases.”

Hussein Rappel

About Spotlight on Young Researchers

Spotlight on Young Researchers is an FNR initiative to highlight early career researchers across the world who have a connection to Luxembourg. This article is the 21st in a series of around 25 articles, which will be published on a weekly basis. You can see more articles below as and when they are published.

Spotlight on Young Researchers: Kacy Greenhalgh

Kacy Greenhalgh has always had an affectation for medicine and health, and how health can be influenced by dietary habits. During her Master studies, the Luxembourg-American national was introduced to FNR ATTRACT Fellow Paul Wilmes and the ‘gut on a chip’, HuMiX. Fascinated by its potential, and how it could be used to study the relation between diet and health, Kacy’s curiosity led her straight to an AFR PhD at the LCSB at the University of Luxembourg.

Spotlight on Young Researchers: Damien Brevers

Postdoc Damien Brevers has a passion for studying self-control abilities in humans. Having spent time in Belgium and the US building expertise in areas including clinical psychology, sport psychology and brain imaging, the Belgian national has just joined the University of Luxembourg and embarked on a project looking at gambling addiction in the age of online betting.

Spotlight on Young Researchers: Maxime Brami

Archaeologist and trained anthropologist Maxime Brami works on uncovering the origins and spread of agriculture, and has just landed a sought-after Marie Skłodowska-Curie Individual Fellowship. We speak to the Luxembourg national about what it’s like to be an archaeologist in academia, the collaborative nature of the field and why archaeologists have a certain responsibility.

Spotlight on Young Researchers: Gil Georges

Gil Georges is driven by the quest for knowledge and strives to have a real impact, beyond publications. The Luxembourg national has just made the jump from early-career researcher to lecturer and group leader at the IET-LAV at ETH Zürich in Switzerland, where the data analyst and modeller gets to use one of Europe’s most powerful super computers when it is time for some serious number crunching.

Spotlight on Young Researchers: Thomas Schaubroeck

Thomas Schaubroeck specialises in sustainability assessment of products. We speak to the Belgian national about the research he is undertaking in the framework of an Industrial Fellowship between the Luxembourg Institute of Science and Technology (LIST) and company Tarkett; how working with industry differs from academia; and how he hopes his research can help industry steer toward a more sustainable future.

Spotlight on Young Researchers: Katharina Baum

When Katharina Baum was a teenager, her mother took her to a presentation about the Human Genome Project. Fascinated, she stood up and asked what she would have to do to be able to study genes. Some years and a degree in mathematics later, the German national and mother of two children now splits her time between Luxembourg and Berlin as part of her two postdocs. In her work at the Luxembourg Institute of Health, Katharina combines computer science, maths and biology to identify faulty regulatory mechanisms in cancerous cells.

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