Friday December 11th, 2026 - 4:15pm - Auditorium BARB92 - Place Sainte-Barbe, 1, 1348 Louvain-la-Neuve

Sustainable hydrogen is expected to play a significant role in the energy transition, as it offers a way to store and deliver usable and clean energy while avoiding direct carbon dioxide emissions at the point of use. The objective of this thesis is to propose strategies to enhance the performance of alkaline water electrolysis and thereby contribute to the development of more efficient electrolyser designs. To this end, computational fluid dynamics (CFD) simulations are used to investigate transport phenomena within water electrolysis cells at both laboratory- and prototype-scales. At laboratory-scale, the incorporation of flow-engineered, laterally graded bilayer electrodes within laboratory cells is considered under forced electrolyte flow conditions. Complex three-dimensional (3D) materials, such as metallic foams and triply periodic minimal surfaces (TPMS) structures, are investigated through a pore-resolved CFD approach. At prototype-scale, flow distribution is quantified using residence time distribution (RTD) analyses. Single-phase flow simulations are used to study flow uniformity and the presence of recirculation regions depending on the inlet configuration and the porous transport layer (PTL). Multiphase flow simulations are subsequently introduced to account for electrogenerated hydrogen bubbles and to investigate the influence of cell geometry on gas distribution and evacuation. Overall, the findings presented here suggest that unlocking the full potential of industrial alkaline water electrolysers will require a more integrated approach to electrolyser design, in which flow fields, porous electrodes, gas evacuation pathways, and cell architectures are co-designed. Such an approach provides a pathway towards more uniform liquid distribution, improved gas evacuation, and more efficient use of the active electrode area, thereby supporting the development and scale-up of high-performance alkaline water electrolysers.

Jury members

Prof. Joris PROOST (UCLouvain), Supervisor
Prof. Aude SIMAR (UCLouvain), Chairperson
Prof. Juray DE WILDE (UCLouvain), Secretary
Prof. Alessandro MONTEVERDE (Politecnico di Torino)
Prof. Benoit SCHEID (ULB)

Pay attention : the public defense of Kevin Van Droogenbroek will also take place in the form of a videoconference

Wednesday November 25th, 2026 - 4:30pm - Auditorium BARB94 - Place Sainte-Barbe, 1 - 1348 Louvain-la-Neuve

The continued scaling of silicon technologies has extended active-circuit operation into the millimeter-wave and sub-terahertz frequency ranges, while interconnects and passive components remain constrained by propagation loss, parasitic modes, fabrication complexity, and packaging. This thesis investigates silicon-based transmission-line and waveguide technologies for integrated sub-terahertz systems, with emphasis on the trade-offs between RF performance, fabrication, integration, and functionality.

The work first establishes an experimental benchmark for planar transmission lines implemented on different silicon technologies and shows that their performance depends on the combined substrate, interface, conductor, and return-path implementation. While planar lines remain suitable for local interconnection and probe access, their accumulated loss limits longer propagation at sub-terahertz frequencies.

Two integrated waveguide platforms are then developed. A DRIE-based silicon-filled rectangular waveguide provides low-loss D-band propagation and high-quality resonators using a bonding-free fabrication approach. The concept is further investigated for post-processing and integration on a foundry CMOS die, highlighting the technological challenges associated with alignment and metallization.

A second platform based on selectively anodized porous silicon enables single-wafer waveguide fabrication without DRIE-defined sidewalls or wafer bonding. Experimental demonstrations include waveguides, resonators, a bandpass filter, and a dielectric sensor.

Together, these results establish complementary silicon-based approaches for sub-terahertz interconnects, passive components, and integrated sensing applications.

Jury members

Prof. Dimitri Lederer   (UCLouvain), Supervisor
Prof. Jean-Pierre Raskin (UCLouvain), Supervisor
Prof. Christophe De Vleeschouwer (UCLouvain), Chairperson
Prof. Laurent A. Francis  (UCLouvain), Secretary
Prof. Isabelle Huynen (UCLouvain)
Prof. Gaël Gautier (Université de Tours, France)
Dr.-Ing. Andreas Rennings (University of Duisburg-Essen, Germany)

Pay attention : the public defense of Shiqi Ma will also take place in the form of a videoconference

Lundi 23 novembre 2026 à 16h00 - Auditoire SUD01 - Croix du Sud - 1348 Louvain-la-Neuve -

Air pollution remains a major threat to human health and ecosystems, yet conventional monitoring networks are costly, too sparse to capture fine-scale variation in exposure, and restricted to a few pollutants. Biomonitoring with lichens offers a complementary approach, since these organisms respond to atmospheric conditions, integrate many contaminants over time, and can be surveyed across large areas. However, inferring air quality from the composition of lichen communities (bioindication) remains hindered by identification difficulties and incomplete knowledge of how species respond to individual pollutants, while the contaminants accumulated in lichen tissues (bioaccumulation) are hard to trace back to their sources, notably because they reflect integrated and partly legacy inputs. This thesis aims to improve the interpretation and applicability of lichen bioindication and bioaccumulation. First, a European meta-analysis identifies species with consistent responses to NH3, NOx, SO2, and climate variables. These responses are then translated into operational indices which, tested in Wallonia (Belgium), partially discriminate NH3 from NOx. In the same region, trace elements accumulated in herbarium and contemporary samples of Xanthoria parietina reveal a marked, element-specific decline in enrichment since the 1960s and identify industry, non-exhaust traffic, and dust resuspension as the main current sources. Analyzing nitrogen content and δ15N indicates that isotopic signatures alone cannot discriminate sources in multi-source landscapes and vary with spatial scale. Finally, to open biomonitoring to non-specialists, the Lichens GO citizen science protocol is evaluated and adapted: targeted changes to sampling and identification procedures improve data quality without increasing sampling effort.
Overall, this thesis supports a more pollutant-specific, source-informed, and widely deployable use of lichens to complement conventional monitoring.

Jury members :

Prof. Yannick Agnan (UCLouvain), Supervisor
Dr. Laure Turcati (Sorbonne Université), Supervisor
Prof. Emmanuel Hanert (UCLouvain), Chairperson
Prof. Guillaume Lobet (UCLouvain), Secretary
Prof. Gabrielle Martin (Toulouse Univ., Fr.)
Prof. Nadine Mattielli (ULB)
Prof. Nathalie Séjalon-Delmas (Toulouse Univ., Fr.)

Pay attention : the public defense of Hugo Counoy will also take place in the form of a videoconference


 

Jeudi 19 novembre 2026 à 15h00 - Auditoire CYCL01 - Bâtiment de Hemptinne - Chemin du Cyclotron, 2 - 1348 Louvain-la-Neuve -

During the Devonian, parts of the ocean repeatedly lost oxygen, with severe consequences for marine life. Rhythms preserved in rocks suggest a link between these crises and slow changes in Earth’s orbit and tilt. This thesis explores how these orbital cycles could have influenced ancient climates and ocean oxygen levels. We use computer models to trace the connections between climate, the continents and the sea. Rainfall affects how rocks break down and how nutrients are carried from land to sea. These nutrients support the growth of marine organisms, whose decay consumes oxygen. To study these interactions over long geological timescales, we develop a faster way to simulate ancient climates. We also investigate how the spread of early land plants changed soils and nutrient delivery, and how changes in underground water storage and land ice could alter sea level. Sea-level changes can reshape shallow seas and their connections to the open ocean, affecting the oxygen available to marine life. The aim is to understand how these linked processes could have contributed to recurring marine crises.

Jury members :

Prof. Michel Crucifix (UCLouvain) (Supervisor)
Prof. Anne-Christine Da Silva (ULiège) (Supervisor)
Prof. Qiuzhen Yin (UCLouvain) (Chairperson)
Prof. Thierry Fichefet (UCLouvain) (Secretary)
Dr. Yannick Donnadieu (CEREGE, Fr.)
Prof. Benjamin J. W. Mills (University of Leeds, U.K.)

Pay attention : the public defense of Loïc Sablon will also take place in the form of a videoconference


 

Wednesday November 18th, 2026 - 4:15pm - Ocean Room, de Serres building (B002) - Place Croix du Sud, 2 - 1348 Louvain-la-Neuve

Estuaries are a key component of coastal systems, influencing hydrodynamics, ecosystem functioning and local socio-economic activities. At the interface between the Scheldt River and the North Sea, the Scheldt estuary forms a strongly convergent channel bordered by intertidal flats and marshes, with the port of Antwerp at its head. The estuary has been extensively modelled for its morphological evolution, dredging strategies and flood management, but storm surges have received less attention, and the estuary and the adjacent sea have rarely been resolved within a single domain. In this thesis, we use the 2D version of the multiscale hydrodynamic model SLIM to study how storm surges propagate and amplify along the Scheldt–North Sea continuum. We first build and validate a configuration that resolves the continuum on a single mesh, from the tidal channels of the upper estuary to the open shelf, over five continuous years. We then assess, for Storm Xaver (2013), how the resolution of the atmospheric forcing affects the simulated estuarine surge, and find that spatial resolution matters more than temporal resolution in this case. Finally, we simulate a panel of plausible future storms under a high-emission scenario up to the end of the 21st century. The panel shows no robust intensification of the meteorological surge over the century, and surge severity varies more with position along the continuum than with storm track, extreme flood levels increasing several-fold from the open sea to the head of the estuary. In this panel, positive and negative surges behave as distinct hazards: the rarest flood levels approach an upper limit, whereas the rarest low waters keep deepening, and Antwerp ranks among the most exposed gauges for both. This thesis provides a single-domain representation of the Scheldt–North Sea continuum and underlines the need to consider both signs of the surge when assessing estuarine hazard.

Jury members

Prof Emmanuel HANERT (UCLouvain), Supervisor
Prof. Marilaure GRÉGOIRE (ULiège), Supervisor
Prof. Marnik VANCLOOSTER (UCLouvain), Chairperson
Dr. Jonathan LAMBRECHTS (UCLouvain), Secretary
Dr. Olivier GOURGUE (Royal Belgian Institute of Natural Sciences)
Prof. Xavier FETTWEIS (ULiège)
Prof. Emil STANEV (Helmholtz-Zentrum Hereon)

Pay attention : the public defense of Ny Riana Randresihaja will also take place in the form of a videoconference