Hafiz Ahmed received a PhD thesis award from the GdR MACS
Hafiz Ahmed - © Inria
Hafiz Ahmed did his PhD among the Non-A project-team (associated with École Centrale of Lille, CNRS and University of Lille − sciences et technologies). His work has just been rewarded by the GdR MACS prizef or thesis.
2017 best thesis prize of the GdR MACS
A native of Dhaka, the capital of Bangladesh, Hafiz Ahmed has been a student in France since his master’s degree. He did his PhD in the Non-A project team. He worked on the development of models to study the behavior of oysters in marine ecosystems in the Arcachon Basin with the aim of identifying disturbances to their biological cycles that may be indicators of water-borne pollution
March 28, the jury of GdR MACS rewarded Hafiz Ahmed for his thesis work. Thesis which has been co-directed by Denis Efimov and Rosane Ushirobira, researchers in Non-A project-team of Inria Lille – Nord Europe center and Damien Tran, CR CNRS, EA team of the laboratory EPOC, Arcachon.
Focus on the thesis
Modeling, analysis and control of oscillations, notably biological rhythms have been studied in this thesis. The thesis is divided into two parts. Part I deals with a real-life application while part II studies more theoretical problems, with potential practical applications. In the first part, motivated by a practical problem of environmental monitoring of coastal environment, this thesis considers the biological rhythms of oysters. Using the information of biological rhythms, an indirect environmental monitoring solution using oysters as bio-sensor has been proposed. The proposed solution works on estimating the perturbation by modeling the biological rhythm of oysters through Van der Pol oscillator model. An inherent limit of this approach is that it works through detecting abnormal behavior only. However abnormal behaviors are not all related to pollution. So, we consider the detection of a particular type of abnormal oscillatory behavior i.e. spawning (behavior during reproduction) which is a natural phenomenon and not related to pollution.
In the second part, oscillations are studied from a theoretical point of view. Having better understanding on the modeling, analysis and control of oscillations may give rise in the future improved environmental monitoring solutions. The first problem of this part is the robustness of oscillations under cell division. Oscillations persist in genetic oscillators (circadian clocks, synthetic oscillators) after cell division. In this thesis, we provide analytical conditions that guarantee phase synchronization after cell division using Phase Response Curve (PRC) formalism. Finally we consider the problem of synchronization of multi-stable systems using Input-to-State (ISS) stability tool. Many oscillatory systems are multi-stable. Using a recent generalization of ISS theory for multi-stable systems, we propose sufficient conditions for the synchronization of multi-stable systems. As a side result, this work has been applied for the global synchronization of a recently proposed oscillator model called theBrockettoscillator.