Topologie algébrique appliquée aux réseaux de capteurs

Simplicial complex representation gives a mathematical description of the topology of a wireless sensor network, i.e., its connectivity and coverage. In these networks, sensors are randomly deployed in bulk in order to ensure perfect connectivity and coverage. We propose an algorithm to discover which sensors are to be switched off, without modification of the topology, in order to reduce energy consumption. Our reduction algorithm can be applied to any type of simplicial complex and reaches an optimum solution. For random geometric simplicial complexes, we find boundaries for the number of removed vertices, as well as mathematical properties for the resulting simplicial complex. The complexity of our reduction algorithm boils down to the computation of the asymptotical behavior of the clique number of a random geometric graph. We provide almost sure asymptotical behavior for the clique number in all three percolation regimes of the geometric graph. In the second part, we apply the simplicial complex representation to cellular networks and improve our reduction algorithm to fit new purposes. First, we provide a frequency auto-planning algorithm for self-configuration of SON in future cellular networks. Then, we propose an energy conservation fot the self-optimization of wireless networks. Finally, we present a disaster recovery algorithm for any type of damaged wireless network. In this last chapter, we also introduce the simulation of determinantal point processes in wireless networks.Simplicial complex representation gives a mathematical description of the topology of a wireless sensor network, i.e., its connectivity and coverage. In these networks, sensors are randomly deployed in bulk in order to ensure perfect connectivity and coverage. We propose an algorithm to discover which sensors are to be switched off, without modification of the topology, in order to reduce energy consumption. Our reduction algorithm can be applied to any type of simplicial complex and reaches an optimum solution. For random geometric simplicial complexes, we find boundaries for the number of removed vertices, as well as mathematical properties for the resulting simplicial complex. The complexity of our reduction algorithm boils down to the computation of the asymptotical behavior of the clique number of a random geometric graph. We provide almost sure asymptotical behavior for the clique number in all three percolation regimes of the geometric graph. In the second part, we apply the simplicial complex representation to cellular networks and improve our reduction algorithm to fit new purposes. First, we provide a frequency auto-planning algorithm for self-configuration of SON in future cellular networks. Then, we propose an energy conservation fot the self-optimization of wireless networks. Finally, we present a disaster recovery algorithm for any type of damaged wireless network. In this last chapter, we also introduce the simulation of determinantal point processes in wireless networks.La représentation par complexes simpliciaux fournit une description mathématique de la topologie d’un réseau de capteurs, c’est-à-dire sa connectivité et sa couverture. Dans ces réseaux, les capteurs sont déployés aléatoirement en grand nombre afin d’assurer une connectivité et une couverture parfaite. Nous proposons un algorithme qui permet de déterminer quels capteurs mettre en veille, sans modification de topologie, afin de réduire la consommation d’énergie. Notre algorithme de réduction peut être appliqué à tous les types de complexes simpliciaux, et atteint un résultat optimal. Pour les complexes simpliciaux aléatoires géométriques, nous obtenons des bornes pour le nombre de sommets retirés, et trouvons des propriétés mathématiques pour le complexe simplicial obtenu. En cherchant la complexité de notre algorithme, nous sommes réduits à calculer le comportement asymptotique de la taille de la plus grande clique dans un graphe géométrique aléatoire. Nous donnons le comportement presque sûr de la taille de la plus grande clique pour les trois régimes de percolation du graphe géométrique. Dans la deuxième partie, nous appliquons la représentation par complexes simpliciaux aux réseaux cellulaires, et améliorons notre algorithme de réduction pour répondre à de nouvelles demandes. Tout d’abord, nous donnons un algorithme pour la planification automatique de fréquences, pour la configuration automatique des réseaux cellulaires de la nouvelle génération bénéficiant de la technologie SON. Puis, nous proposons un algorithme d’économie d’énergie pour l’optimisation des réseaux sans fil. Enfin, nous présentons un algorithme pour le rétablissement des réseaux sans fil endommagés après une catastrophe. Dans ce dernier chapitre, nous introduisons la simulation des processus ponctuelsdéterminantaux dans les réseaux sans fil

A Statistical Approach to Topological Data Analysis

Until very recently, topological data analysis and topological inference methods mostlyrelied on deterministic approaches. The major part of this habilitation thesis presents astatistical approach to such topological methods. We first develop model selection toolsfor selecting simplicial complexes in a given filtration. Next, we study the estimationof persistent homology on metric spaces. We also study a robust version of topologicaldata analysis. Related to this last topic, we also investigate the problem of Wassersteindeconvolution. The second part of the habilitation thesis gathers our contributions inother fields of statistics, including a model selection method for Gaussian mixtures, animplementation of the slope heuristic for calibrating penalties, and a study of Breiman’spermutation importance measure in the context of random forests

Wireless communication services to support teams of cooperating autonomous robots

This work will consist in investigating wireless communication protocols to provide services that are commonly required to support cooperation among autonomous robots. Particular attention will be dedicated to RF-based relative localization services that are infrastructure-free. The main idea is to research the joint use of RF-ranging with RSSI-based techniques to develop a system that has improved accuracy with faster response. Beyond these services, the work will also address local state data sharing and global point-to-point communication on a volatile topology. Using a self-synchronization technique, the work will build upon previous efforts to track the topology and provide reservations (channels) on-demand, that route communications between nodes

Interoperability enhancement of IoT devices using open web standards in a smart farming use case

Dissertation submitted in partial fulfilment of the requirements for the Degree of Master of Science in Geospatial TechnologiesSince its rst appearance the Internet of Things has been subject to constant evolution, development and change. Now it has stepped out of its infancy with billions of devices embedded in the world wide web. However, IoT providers mostly de ne their own data formats and protocols and there is still a lack of a common standard that connects these devices in an interoperable manner. There are several organisations dedicated to developing common standards for IoT devices and research is focusing on de ning an e ective standard to be used by embedded devices. Unsurprisingly, IoT has also found its way into the spatial web and into environmental monitoring and sensing platforms connected over the web by wireless sensor networks are now a common way to monitor natural phenomena. This study compares three open Web Standards in the use case of SEnviro for Agriculture, a full stack IoT for monitoring vineyards. The interoperability potential of the OGC's Sensor Observation Service and SensorThings API are evaluated by integrating Web Standard implementations for each standard and contrasting their qualitative and quantitative traits. In a further step the Mozilla Corporation's Web Thing API was implemented and evaluated in an environmental monitoring and Smart Farming context. The results of the study show that the SensorThings API proves to be the most adequate Web Standard for SEnviro and IoT applications for environmental monitoring and Smart Farming in terms of interoperability. It outperforms the contesting Web Standards in terms of exibility and scalability, which strongly impacts on developer and user experience

Autonomous, Collaborative, Unmanned Aerial Vehicles for Search and Rescue

Search and Rescue is a vitally important subject, and one which can be improved through the use of modern technology. This work presents a number of advances aimed towards the creation of a swarm of autonomous, collaborative, unmanned aerial vehicles for land-based search and rescue. The main advances are the development of a diffusion based search strategy for route planning, research into GPS (including the Durham Tracker Project and statistical research into altitude errors), and the creation of a relative positioning system (including discussion of the errors caused by fast-moving units). Overviews are also given of the current state of research into both UAVs and Search and Rescue

Applications of Satellite Earth Observations section - NEODAAS: Providing satellite data for efficient research

The NERC Earth Observation Data Acquisition and Analysis Service (NEODAAS) provides a central point of Earth Observation (EO) satellite data access and expertise for UK researchers. The service is tailored to individual users’ requirements to ensure that researchers can focus effort on their science, rather than struggling with correct use of unfamiliar satellite data

Satellite monitoring of harmful algal blooms (HABs) to protect the aquaculture industry

Harmful algal blooms (HABs) can cause sudden and considerable losses to fish farms, for example 500,000 salmon during one bloom in Shetland, and also present a threat to human health. Early warning allows the industry to take protective measures. PML's satellite monitoring of HABs is now funded by the Scottish aquaculture industry. The service involves processing EO ocean colour data from NASA and ESA in near-real time, and applying novel techniques for discriminating certain harmful blooms from harmless algae. Within the AQUA-USERS project we are extending this capability to further HAB species within several European countries

Condition monitoring of belt based motion transmission systems

A key asset of Royal Mail Group consists of a nationwide network of sorting offices that forms a constituent component of the means through which the organisation provides an efficient nationwide postal service within the United Kingdom. It may be argued that the efficiency currently possessed by modem sorting offices is due to the utilisation of machines that automate the process of sorting items of mail. The modem letter-sorting machine possessed by Royal Mail can sort up to 30,000 letters per hour; such machines serve as an example of an achievement of the application of Mechatronics. The maintenance of letter sorting machines constitutes a large overhead for the organisation. In the face of competition from pervasive electronic media within the personal communications market and the prospect of deregulation, Royal Mail seeks to streamline its operation in part by the reduction of the overheads incurred through maintenance of letter sorting machinery. The adoption of condition based maintenance techniques and predictive maintenance, for letter sorting machine components such as belts and bearings, forms part of the strategy through which Royal Mail seeks to reduce this overhead. Utilisation of flat belts and timing belts for the implementation of key functions in letter sorting machinery, such as the transportation of items of mail within the mail sorting process, results in the use of many such components within letter sorting machinery. A direct link exists between the maintenance of peak performance of a sorting machine and the maintenance of belt drives; as such the maintenance of belt drives forms a substantial component of the maintenance overhead. The focus of this thesis consists of the condition monitoring of belt based motion transmission systems and in particular, flat belts. The research that forms the basis of this thesis consists of three elements. Firstly, consideration of current knowledge of belt based power transmission such as knowledge of the mechanics of the belt based power transmission process within the context of condition monitoring... [cont'd