EDCE Awards laureates

Dr. Anne-Claire Billault-Roux

Ph.D. in the Environmental Remote Sensing laboratory, LTE

Thesis title: Snowfall microphysics: a dual-frequency and Doppler spectral radar perspective

Snowfall is an essential component of the hydrological cycle, as it is involved in most precipitation on Earth, either directly as snow falling to the ground or indirectly as rain melted from snow. At the same time, the ice phase in clouds and precipitation is a key contributor to the Earth’s radiative budget, making it a crucial aspect of climate-oriented research. Properly modeling snowfall for both weather and climate applications requires knowledge of the “microphysics of snowfall”, that is, a microscale description of snow particles and of the mechanisms by which they form, grow, and decay.

Among different approaches to studying snowfall microphysics, remote sensing techniques and, in particular, meteorological radars, offer decisive insights. The goal of my thesis was to investigate the microphysical properties and processes of snowfall by relying primarily on measurements from radars transmitting at different frequencies and on radar Doppler spectra – which disclose how radar signals are distributed between large, fast-falling, and small, slow-falling particles.

One aspect of my work consisted in collecting a multi-sensor dataset of in situ and remote sensing measurements of snowfall, during a field campaign in the Swiss Jura mountains. I then introduced new methods to retrieve cloud and snowfall properties from remote sensing measurements, making use of cutting-edge machine-learning techniques. With a slightly different perspective, I then focused on a specific snowfall event: there, we showed that a lot could be learnt, using radar measurements, about certain ice growth and multiplication mechanisms which are still poorly understood. Overall, this work sheds a new light on remote sensing studies of snowfall microphysics, both in terms of quantifying snowfall properties, and understanding the complex processes at work.

As a postdoctoral researcher at the Environmental Remote Sensing laboratory, I am currently working on a continuation of the research questions I explored during my thesis. My goal is to better characterize the intrinsic limitations and uncertainties of such radar-based studies of cloud and precipitation microphysics, to understand how far we can hope to take them.

Dr. Mahmood Hamze Ziabari

Ph.D in the Ecological Engineering Laboratory, ECOL

Thesis title: Unraveling submesoscale processes associated with meso- and basin-scale gyres in Lake Geneva

The evaluation of biological, chemical, and physical processes within large lakes, alongside the study of how climate change impacts these processes, mainly relies on conventional single-station monitoring techniques. These methods overlook the lateral variability inherent in the three-dimensional (3D) processes occurring in large lakes. By integrating field observations, 3D numerical simulations, Lagrangian particle tracking, remote sensing data, and statistical analyses, my thesis investigates the dynamics of rotating coherent water masses and their associated submesoscale processes in Lake Geneva. The primary objective of my thesis was to detect and examine previously unobserved or studied 3D physical processes that have been overlooked in the field of limnology. Furthermore, the aim was to elucidate the implications of these dynamics for water quality heterogeneity.

First, a novel framework is developed that permits study the spatiotemporal characteristics of basin-scale and mesoscale processes during different seasons by allowing efficient design of field sampling strategies with unprecedented precision in time and space. Building on this novel framework, the existence of submesoscale processes caused by large-scale gyres is demonstrated for the first time in a lake. The dynamics of pelagic upwelling within a cyclonic gyre in Lake Geneva were investigated. The spatial heterogeneity of water quality parameters caused by (sub)mesoscale flow features is then revealed.

In general, my thesis offers new perspectives on how (sub)mesoscale processes impact the vertical exchange of heat, contaminants and oxygen between the atmosphere and the pelagic zone of large lakes, as well as in oceans where carrying out such field measurements is very challenging.

As a postdoctoral researcher at the CRYOS lab, I am currently involved in the UrbanTwin project. My main focus is on examining the impact of heat islands formed during heatwaves on the temperature of Lake Geneva, as well as investigating how climate change might affect the natural ventilation provided by Lake Geneva in the city of Lausanne.

Dr. Andronikos Skiadopoulos

Ph.D. at the Resilient Steel Structures Laboratory, RESSLab

Thesis title: Welded Moment Connections with Highly Dissipative Panel Zones for Enhanced Seismic Performance of Steel Moment Frames

Research conducted after the 1994 Northridge earthquake in the U.S. and the 1995 Kobe earthquake in Japan led to the development of today’s welded beam-to-column connections for steel moment resisting frames in high-seismicity regions. To mitigate fracture-related issues, welded moment connections over the last 25 years feature rigorous weld details that are challenging from a fabrication standpoint. Moreover, the stable hysteretic response of the column web panel zones is not exploited, leading to concentration of damage in the steel beams in the advent of moderate earthquake events, thereby engendering structural repair costs.
My doctoral thesis aimed at advancing the state-of-knowledge regarding the seismic design and behavior of steel moment resisting frames with highly dissipative column web panel zones. Firstly, I developed a new panel zone model that addresses the limitations of available models in literature. The reliability of the developed model allows for a seismic design that exploits the beneficial aspects of panel zone shear yielding. One step further, in my thesis I revisited the current detailing of welded connections by proposing simplifications in their fabrication process, without impairing the connection’s ductility. Full-scale experiments of the proposed connection demonstrated that, contrary to the current design paradigm, a stable hysteretic response is achieved until unrealistically large lateral drifts. Finally, in my doctoral thesis I demonstrated through large-scale system level simulations that steel moment resisting frames designed with the proposed connection design methodology enjoy up to two times lower seismic collapse risk and reduction in the structural repairs in the advent of earthquake events compared to the current status quo.
As a postdoctoral fellow at EPFL in the Resilient Steel Structures Laboratory (RESSLab), I am currently focusing on characterizing fracture in welded moment connections for capacity designed steel moment resisting frames.

Dr. Joseph Lemaitre

Ph.D at the Laboratory of Ecohydrology, ECHO

Thesis title: Modeling infectious disease dynamics towards informed public health interventions, with applications on COVID-19 and cholera

Centuries after the first cholera pandemics and 160 years after the realization that safe drinking water and adequate sanitation prevent its transmission, cholera remains a threat to millions living in hotspots or at-risk areas. The recent emergence of the new coronavirus disease 2019, COVID-19, and the strain it put on the world’s most advanced healthcare systems recalls the constant risks posed by emerging diseases. Today, communicable diseases cause approx. 15% of global deaths every year. In many cases, the burden of these diseases is preventable through public health interventions. However, taking the right decisions and designing effective policies is an intricate task: epidemics are complex phenomena resulting from the interaction between the environment, pathogens, individuals, and societies. 
My thesis explores modeling as a way to reason about infectious disease dynamics from scarce and biased information and to guide decision-makers toward effective policies. The results presented range from scientific insight on the relationship between cholera and rainfall in Juba, South Sudan to the COVID Scenario Pipeline, a modeling framework that produces reports used to inform the response to the COVID-19 pandemic of different governmental entities. Furthermore, the effectiveness of the non-pharmaceutical interventions against COVID-19 in Switzerland is evaluated; and so is the probability of eliminating cholera from Haiti under different scenarios of mass vaccination campaigns. Finally, the development of an optimal control framework towards the effective spatial allocation of vaccines against SARS-CoV-2 in Italy closes this conversation of models. From scientific insights on transmission pathways to weekly reports distributed to health officials, my thesis demonstrates how infectious disease modeling enables informed decision-making by projecting uncertainties under the light of the available evidence. It also highlights the effort needed to tailor the models and inference methods to the specificities of the transmission setting and the research question considered. Methods developed along the way enrich the toolbox available to modelers, to guide policy decisions further toward a reduction of the burden of infectious diseases on communities around the world.
As a postdoctoral researcher at the Gillings School of Global Public Health at the University of North Carolina at Chapel Hill, I am currently working on the direct continuation of my thesis, producing regular forecasts of influenza and COVID-19 transmission while developing novel statistical approaches for infectious disease modeling.

Massimo Bourquin – Jury Award

Global Response of Glacier-Fed Stream Bacterial Microbiome to Climate Change

The poster “Global Response of Glacier-Fed Stream Bacterial Microbiome to Climate Change” delves into the implications of climate change on the glacier-fed stream ecosystem. Using a modelling approach combined with a global sampling of glacier-fed streams gathered by the Vanishing Glaciers Project, this study aims at understanding how these unique ecosystems will be altered by the combined effect of climate change and glacier shrinkage, especially the bacterial communities. Under future conditions, the latter are predicted to overall increase in abundance as primary production increases. However, this growth is accompanied by ecological shifts and we highlight potential risks to specific taxa. Additionally, the modelling approach enabled to improve our comprehension of how climate, glacier influence, and physicochemical factors interplay to shape glacier-fed stream ecological communities.

Cloe Cortes Balcells – Audience Award

Mobility and Individual Choices in Infectious Disease Spread: Enhacing Activity-Based Models with Awareness and Testing Dynamics

The SARS-CoV-2 pandemic highlights the need to understand human mobility for disease control. Mobility patterns, vital in virus transmission, require modeling individual behaviors. The epidemiological models can be categorized into three types: compartmental, network-based, and activity-based. Although activity-based models demand greater computational resources, they allow a more detailed representation of individual behaviors, positioning them as critical for predicting the spread of a disease. However, the literature indicates that these models tend to focus primarily on infection probabilities, overlooking personal choices like testing decisions. This study refines the activity-based model by integrating latent states for agents’ behavior, combining infection probabilities, and testing propensities based on health and socioeconomic factors.

A core element of our model is the ‘awareness’ indicator modeling if an individual knows to be infected. From a mobility standpoint, awareness is crucial as an individual’s activity-travel behavior is altered only when being aware of the infection. Using a dynamic, fully disaggregated model, we trace each individual’s decision-making sequence, offering a detailed perspective on testing decisions and daily infection dynamics.

Tatjana Milojevic – Jury Award

Impacts of Extreme Precipitation on Alpine Reservoirs
This poster is about the investigation of the impacts of extreme precipitation and drought events on Alpine reservoirs. First, a comparison of traditional and novel approaches for determining the return periods of extreme events is presented. These results, in combination with general expected changes in precipitation in Switzerland (both average and extreme) are used to generate precipitation (or drought) sample scenarios across different seasons.  Potential impacts on reservoir water levels and the resulting effects on electricity production potential in various seasons are then shown. The important point is that not all reservoirs are equally vulnerable to the same type of event or at the same time of year. Therefore, understanding the spatial dynamics of extreme events and assessing the impact risk at a local level is a critical next step.

Marko Pejatovic – Audience Award

Are our bridges “tired”

The poster design is symbolically linked to cracks in concrete.

Cracked concrete structures are typically acceptable, but not always. There are different conditions when cracks have to be verified. One of the cases when cracks might be problematic refers to stress concentrations in steel reinforcing bars close to cracks due to the dowel action (the transverse force causing the local bending of the reinforcement).

The poster presents relevant steps of an experimental investigation on the dowel action in concrete structures. First two steps show the test set-up and a specimen which is equipped by advanced measurement devices such as Digital Image Correlation (DIC) and Optical Fibres. Representative results based on these measurements are treated in steps 3-5. The step 6 at the bottom of the poster gives a chance to ask a question.

Janisse Deluigi

The aim of my PhD at the Plant Ecology Research Laboratory (PERL) is to determine how warming and drought individually and simultaneously impact tree net carbon uptake and the potential role of biodiversity in modulating these effects in natural forests.

Over the past years, I conducted a climatic manipulation in open-top chambers and a field experiment in a natural forest in the warm and dry region of Valais, to assess trees responses and acclimation capacity to a warmer and drier climate and the modulating role of tree species interactions. During these experiments, I realized that while increasing species diversity is a forest management strategy widely used to mitigate climate change impacts, little is known about how these more diverse forests are created.

During my academic visit at the University of Freiburg, I will have the opportunity to work with Prof. Jürgen Bauhus, who is the leader of the Chair of Silviculture and has a deep knowledge on forest management and climate change ecology. Under his guidance, I would like to review how more climate-resistant forests are created, where do they occur and what are their consequences for ecosystem functions and processes, providing key information for the community working in this field and beyond.

Jaïr Campfens

My PhD research at EPFL focuses on using participatory modelling to develop sustainable energy scenarios. More specifically, my work integrates quantitative modelling approaches with socio-technical insights to achieve high shares of decentralized renewable energy for Swiss cities, midlands, and alpine regions.

During my academic visit to the Planning of Landscape and Urban Systems (PLUS) group, I will specialize myself in Dynamic Bayesian Networks (DBNs), which add a temporal dimension to traditional Bayesian Networks. These models will track changes in key energy indicators, such as greenhouse gas emissions, over time, making them highly relevant for long-term energy planning.

Through three workshops in the Swiss city of Winterthur, I will validate the DBNs with stakeholders, ensuring their practical applicability. By engaging with stakeholders, my research bridges the gap between theoretical models and practical implementation. This collaboration with the PLUS group will advance my research and contribute innovative tools for energy transition planning in Switzerland.

Thibaut Juillard

In the frame of my Ph.D. studies at the Plant Ecology Research Laboratory (PERL), I study the spread of non-native evergreen tree species in Switzerland, in particular invasive palm trees. In natural forests, these exotic species compete with the local ones and may alter their growth and survival, having negative consequences on biodiversity, wood production, nutrient cycling, etc.

The effect of drought events on these species is poorly understood and could have positive or negative impacts on their spread. For this reason, I am interested in measuring physiologic traits related to reduced water availability in exotic plants.

During my academic visit to the University of Tasmania (UTAS, AU), I will have the opportunity to work with Prof. Tim Brodribb, who is a renowned ecophysiologist specializing in plant water transport and use. In particular, he developed a novel, non-destructive method for measuring drought impacts on plants’ leaves and stems using cameras. Under his expert guidance, I would like to learn how to use this method and develop a measurement station at EPFL.

Valérie Zermatten

A member of the Environmental Computational Science and Earth Observation Laboratory (ECEO)

In collaboration with Swisstopo, my PhD project is centered around the application of deep learning techniques to map mountain ecosystems by leveraging diverse data sources, including remote sensing imagery, crowdsourced species observations, and textual descriptions. During the initial stages of my PhD, I developped an interpretable and interactive approach for characterizing terrestrial ecosystems based on aerial imagery provided by Swisstopo.

The next phase of my project aims to integrate  species observations obtained from citizen scientists  database such as the PlantNet Project. This task poses significant challenges, as crowdsourced observations are susceptible to various sources of biases, from the irregular collection process to species misidentification.

My research stay at the National Institute for Research in Digital Science and Technology (INRIA) in Montpellier, France, is a great opportunity for working alongside Prof. Diego Marcos and Prof. Alexis Joly, member of the PlantNet Project since its start. This collaboration  allows me to gain valuable insights into how to effectively exploit crowd-sourced ecological data, ultimately enhancing the characterization of alpine ecosystems.

Negar Rezvany

As a member of the Transport and Mobility Laboratory (TRANSP-OR), I am conducting research on integrating interactions into activity-based models. We have developed a methodology that reconstructs the daily activity schedules of individuals in a household, explicitly accommodating complex interactions among household members such as allocation of the car to household members, escorting children, joint participation of household members in activities, and sharing rides. This methodology uniquely allows capturing multiple interaction dimensions within the same framework. This framework differs from the existing activity-based models treating individuals as isolated agents, which are limited in their demonstration of behavior. Understanding and predicting complex behavior and interactions is the key to better demand-side management and adapting infrastructure systems (transportation, energy, etc.) to deliver critical services that meet the needs of society. The model works well with multi-member households and captures complex behaviors and interactions.

The Human-Centric Modelling Laboratory, directed by Dr. Tim Hillel at University College London (UCL), is focused on developing decision-aid models and tools to plan future built environments (spanning a variety of fields such as mobility, energy consumption, or infrastructure maintenance) by considering holistic systems centered around people. My academic visit to UCL would allow me to work more closely with Dr. Tim Hillel on the application of our developed methodology in addition to exploring other practical extensions of our framework in collaboration with researchers at UCL.

Qianqing Wang

Member of Earthquake Engineering and Structural Dynamics Laboratory (EESD)
Masons with years of training are needed for the construction of masonry structures. However, the scarcity of skilled masons motivates us to create intelligent construction robots for improving the productivity of the construction industry aiming at the reduction of its environmental impact. In this regard, my PhD thesis focuses on the development of efficient methods for guiding robots to perform stone-stacking tasks aiming at specific design requirements, such as seismic load resistance. Currently, I am developing an image-based stacking algorithm for finding the best sequence of actions for placing stones during the construction of stone masonry walls. Given photos of available stones, the algorithm tells robots how to select stones and where to place it. However, the computational cost of this approach could be prohibitive for real-time applications.
During my academic visit to the University of Minnesota, I plan to work with Prof. Dos Santos to create a model-free solution based on reinforcement learning. Prof. Dos Santos is an expert in the development of numerical methods for optimization and uncertainty quantification of complex engineering systems. His expertise in machine learning will help me develop an efficient decision-making framework for large-scale buildings made of irregularly-shaped stones. We expect the method to be broadly useful for application in autonomous construction.