Cluster analysis for multivariate data in micropaleontology

In collaboration with a PhD student in micropaleontology and in order to understand the evolution of fossilized marine organisms, we conducted several statistical analyzes to determine whether the characteristic dimensions of these organisms allowed them to be grouped into different families. These analyzes were conducted for two distinct observation periods at different geographical locations.

Ref: Dr Monica Constandache,
Ref: Dr Monica Constandache, “Morphometric study of porosity and morphology of fossil Globigerinoides, during the Late Oligocene and Early Pliocene”

Psychosoziale Risiken, die auf den wahrgenommenen Konflikt zwischen Arbeit und Privatleben zurückzuführen sind: Rolle einiger organisatorischer und psychografischer Variablen – Eine empirische Studie bei einer Schweizer Polizei

In dieser Studie versuchen wir, die Mittel zu identifizieren, die einer öffentlichen Organisation zur Verfügung stehen, um Konflikte im Berufsleben der Polizei zu verhindern.

Um dies zu tun, werden wir versuchen zu verstehen, was sind die Auswirkungen bestimmter organisatorischer Variablen (die Wahrnehmung der Autonomie, die Anforderungen der Aufgabe, soziale und organisatorische Unterstützung) und eines psychografischen Variables (das Gefühl der Kohärenz) auf die Wahrnehmung dieses Konflikts.

Unsere gemischte Methodik mobilisiert verschiedene Ansätze: eine quantitative Studie und Einzelinterviews.

pexels-photo-289588

Structure and Dynamics of Niche-Overlap Graphs

food web


This project was conducted during my PhD thesis: a joint collaboration between the University of Fribourg (Ecology and Informatics departments) and the HEIA-FR. Using a real dataset of niche-overlap graphs (graphs that depict the competition between species in the nature), we firstly developed a novel algorithm to detect efficiently chordless cycles and showed that these cycles are numerous in these graphs. Secondly, we investigated the structure of these networks using the theory of graphs. Finally, we simulated the abundance of species over time using systems of Lotka-Volterra differential equations and investigated the persistence of these species inside niche-overlap graphs networks using a generalized linear model.

Gas balloon dynamics

ballon

The Gordon Bennett race (https://en.wikipedia.org/wiki/Gordon_Bennett_Cup_(ballooning)) is the oldest and the most popular gas balloon race.

We have developped a model that captures the trajectory of a gas balloon. With some sensors installed in the gondola we can anticipate potential instable atmospheric situations and predict the sand and gas consumption.

delestage

Moreover, we have developped tools to predict the trajectory of a balloon.

trajectoire

See Fribourg Freiburg Challenge for some nice pictures and videos.

Jupyter: a datascience interactive platform

Jupyter logo

The ASAM Group has recently launched its jupyter hub.  The project intends to give students a set of interactive courses, as an introduction to the statistical software R. Thank Jupyter, one has the possibility to learn and test in a “live” environment line codes from different languages, as R, Python, Julia, etc.  In the next years, the applied statistics master courses given by the ASAM Group will be each completed by jupyter notebooks.

Absolute vs relative Kennzahl

key performance indicator

Um die Absatzzahlen verschiedengrosser Verkaufskanäle sinnvoll vergleichen und interpretieren zu können, sind absolute und relative Messungen unzureichend. In diesem Projekt wurde ausgehend von wenigen ökonomisch natürlichen Axiomen eine neue Kennzahl entwickelt, welche die Vergleichbarkeit verschiedener Kanäle auf verschiedenen Skalen ermöglicht. Die Grösse ist auch in Bezug auf die Grundlagenforschung interessant, weil sie einerseits einen Bezug zwischen Grenzfunktionen und ökonomischer Elastizität offenlegt und andererseits als spezielle Cobb-Douglas-Funktion interpretiert werden kann.

Mechanik des Pflanzenwachstums

Air quality investigations in new and renovated energy-efficient houses

 image_mesqualair_copyright_felix

In order to study the air quality in houses, a large collection of data was carried out in new or renovated energy-efficient houses from Western Switzerland. The statistics consisted of analyzing questionnaires completed by the inhabitants as well as the measures of radon, volatile organic compounds and occurrence of molds. We had also to find which parameters (structure of the house, type of ventilation, maintenance,…) have an influence on a high level of radon, of volatile organic compound and mold.

Mathematik in Ihren Diensten