Author: Antoine Boutet

Workshop on Performance Guarantees in Wireless Networks – 08-09/03 @LINCS

The CITI is glad to participate to a 2-day Workshop entitled Performance Guarantees in Wireless Networks, organized by François Baccelli (Inria and Télécom-Paris) and Jean-Marie Gorce (Insa Lyon and Inria Lyon).

The workshop will take place on March 2023, Wednesday 8th and Thursday 9th, @LINCS: Télécom-Paris, 19 place Marguerite Perey, Palaiseau, Amphi Rose Dieng.

The web site of the event is here and the list of the confirmed invited speakers and the program are there.

IMPORTANT! Registering is required to attend.


CITI seminar – Pablo Rauzy (Université Paris 8) – 10/02 at 12:15

Speaker: Pablo Rauzy (Université Paris 8)

Date: 10/02/2023

Time: 12h15

Place: Amphi Chappe/Lamarr, 6 avenue des arts, La Doua Campus

Title: Promesses et (dés)illusions : une introduction technocritique aux blockchains

Abstract: Une blockchain est un registre distribué et immuable dans lequel sont écrites des informations qui font consensus. ». Dans cet article, nous commencerons par donner du sens à cette phrase et à l’ensemble des termes qui y sont employés, en nous efforçant quand c’est nécessaire de rendre accessibles les notions informatiques (comme la décentralisation, la distribution, l’immuabilité, ou le consensus) et le fonctionnement technique des outils cryptographiques sous-jacents (comme les condensats, les signatures, ou la preuve de travail ou d’enjeu). L’objectif de cette introduction sera d’atteindre une compréhension réelle de ce qu’est une blockchain.

Ainsi équipé·es, nous discuterons ensuite de ce que les blockchains permettent effectivement d’accomplir, et donc surtout ce qu’elles ne permettent pas. Nous questionnerons alors les utilisations qui en sont proposées en nous concentrant sur des cas d’usage typiques des blockchains que nous étudierons plus en détails : les « cryptomonnaies » bien sûr, la certification de documents (avec l’exemple des diplômes), et nous mentionnerons également le cas des NFT. Cela nous permettra en conclusion de questionner de manière générale le caractère d’« innovation de rupture » que l’on associe souvent à cette technologie.

Bio: Pablo Rauzy est maître de conférences en informatique à l’Université Paris 8 et membre de l’équipe PASTIS du LIASD. Avant sa prise de poste à Paris 8 en 2016, il a été doctorant dans l’équipe SEN de Télécom ParisTech puis post-doctorant dans l’équipe Inria Privatics au CITI. Ses travaux de recherche portent de manière générale sur la sécurité et touchent à différents aspects du domaine — privacy et contrôle, formalisation et modélisation, cryptographie et implémentation —, toujours avec la volonté d’une approche émancipatrice consciente du caractère non-neutre des sciences et technologies. C’est ce souci qui l’a conduit à devoir finalement s’intéresser aux blockchains dans le cadre de sa recherche, pour rendre accessible au plus grand nombre leur fonctionnement, leurs limites, et leurs dangers.


CITI seminar – Eleftherios Kofidis (University of Patras) – 24/01 at 14:00

Speaker: Eleftherios Kofidis (University of Patras)

Date: 24/01/2023

Time: 14h00

Place: Amphi Chappe/Lamarr, 6 avenue des arts, La Doua Campus

Title: Tensor methods and applications

Abstract: Tensor models have been well established as a natural and powerful way of representing systems and data that involve multiple aspects/dimensions. Assisted by their unique ability to unveil latent information through tensor decomposition methods, they have proved successful in numerous applications. In this talk, I will present some of our recent work and results on tensor methods, with example applications including wireless communications and remote sensing.

Bio: Eleftherios Kofidis received the Diploma (MEng) and Ph.D. degrees in 1990 and 1996, respectively, both from the Department of Computer Engineering and Informatics, University of Patras, Patras, Greece. From 1996 to 1998 he served in the Hellenic Army. In the period 1998 to 2000, he was a postdoctoral fellow at the Institut National des Télécommunications (INT), Évry, France (now Télécom SudParis). From 2001 to 2004, he was a research associate at the University of Athens, and adjunct professor at the Universities of Peloponnese and Piraeus, Greece. In 2004, he joined the Dept. of Statistics and Insurance Science, University of Piraeus, Greece, where he is now Associate Professor. He is also affiliated with the Computer Technology Institute & Press “Diophantus” (CTI), Greece. His research interests are in signal processing and machine learning, with applications including communications and medical imaging. He has served as technical program co-chair and in the organization and technical program committees of a number of conferences. Dr. Kofidis has served as Associate Editor in the IEEE Transactions on Signal Processing, the EURASIP Journal Advances in Signal Processing, and the IET Signal Processing journal.


PhD Defence: “Resilient IoT-based Monitoring System for the Nigerian Oil and Gas Industry”, Safuriyawu Ahmed, amphi est, bâtiment des humanités, 16th of December 2022 at 10 AM

The defense will take place on Friday 16th December at 10 AM in the est amphi of the Humanities building, Insa-Lyon, Villeurbanne.

 

Title

Resilient IoT-based Monitoring System for the Nigerian Oil and Gas Industry

 

 

Abstract

Pipeline failures in crude oil transportation occur due to ageing infrastructure, third-party interferences, equipment defects and naturally occurring failures. Consequently, hydrocarbons are released into the environment resulting in environmental pollution, ecological degradation, and unprecedented loss of lives and revenue. Hence, multiple leakage detection and monitoring systems (LDMS) are employed to mitigate such failures. More recently, these LDMS include Wireless Sensor Networks (WSN) and Internet of Things (IoT)-based systems. While they are proven more efficient than other LDMS, many challenges exist in their adoption for pipeline monitoring. These include fault tolerance, energy consumption, accuracy in leakage detection and localisation, and high false alarms, to cite a few.

Therefore, our work seeks to address some of these challenges in implementing IoT-based systems for crude oil pipelines in a resilient end-to-end manner. Specifically, we consider the aspect of accurate leakage detection and localisation by introducing a unique node placement strategy based on fluid propagation for sensitive and multi-sized leakage detection. We also propose a new distributed leakage detection technique (HyDiLLEch) in the WSN layer. It is based on a fusion of existing leakage detection techniques such as the negative pressure wave method, gradient-based method, and pressure point analysis. With HyDiLLEch, we efficiently eliminate single points of failure.

Furthermore, we implement fault-tolerant data and service management in the fog layer utilising the Nigerian National Petroleum Corporation (NNPC) pipeline network as a use case. The problem is modelled as a regionalised data-driven game against nature on the NNPC pipelines. Our proposed regionalised solution (R-MDP) using reinforcement learning optimises accuracy and fault tolerance while minimising energy consumption.

Overall, our system guarantees resiliency to failures and efficiency in terms of detection and localisation accuracy and energy consumption.

 

Jury

  • Stolf, Patricia, Professeur des Universités, Université de Toulouse, Rapporteure
  • Guidec, Frédéric, Professeur des Universités, Université Bretagne Sud, Rapporteur
  • Menaud, Jean-Marc, Professeur des Universités, IMT-Atlantique, Examinateur
  • Caron, Eddy, Maître de Conférences, ENS Lyon, Examinateur
  • Takruri-Rizk, Haifa, Professeur des Universités, University of Salford, Examinatrice
  • Silva, Bhagya Nathali, Senior Lecturer, University of SriJayawardenepura, Examinatrice
  • Le Mouël, Frédéric, Professeur des Universités, INSA Lyon, Directeur de thèse
  • Stouls, Nicolas, Maître de Conférences, INSA Lyon, Co-Directeur de thèse
  • Yusuf, Kabir, Docteur en gestion des ressources environnementales, PTDF/SAPZ, Invité

PhD Defence: “Contributions to the development of passive RFID tag-to-tag communications for the Internet of Things”, Tarik Lassouaoui, amphi ouest, batiment des humanités, 16th of December 2022 at 10 AM

The defense will take place on Friday 16th December at 10 AM in the west amphi of the Humanities building, Insa-Lyon, Villeurbanne.

Title

Contributions to the development of passive RFID tag-to-tag communications for the Internet of Things

Abstract

With the emergence of cognitive sensor networks, and in particular the IoT (Internet of Things), passive RFID (Radio Frequency Identification) UHF (Ultra High Frequency) technology is evolving with new functionalities. New types of applications going beyond the classics such as logistics, security and traceability are being developed. Still benefiting from unitary identification, new types of tags, called augmented tags, are appearing integrating new capacities such as environmental sensitivity, cognitive behaviour, data processing, communication between tags, etc. In this context, the objective of this thesis is to propose strategies and methods to optimize communications between tags, called tag-to-tag “tag-to-tag” (T2T) communications. This new type of radio link, between directly communicating tags, relies on the presence of an external radio frequency (RF) source and is based on the principle of retro-modulation. In particular, the scenarios analyzed are projected within the framework of the Spie ICS – INSA Lyon chair, which focuses on the IoT.

This thesis more specifically targets the application domain of UHF RFID for which the concept of T2T communications has been proposed and demonstrated since 2011, but with relatively little work done so far. In a T2T RFID system, two RFID tags (passive or semi- passive) communicate with each other directly without going through the reader. One of the tags plays the role of “reader tag”: in the presence of an RF source (for example an RFID reader) in its vicinity, it emits binary information by retro-modulation (or backscatter by switching charges), by switching the load seen by its antenna on two distinct impedances, thus reflecting two distinct power levels (modulation here considered in amplitude). The other tag plays the role of “receiver tag”: it receives the information transmitted and demodulates it.

In the traditional case of UHF RFID, the reader emits, in accordance with the standard, a modulated signal with a high modulation depth in order to facilitate the detection of the message transmitted by the tag. The tag responds by retro modulation and the signal it returns is then a signal where the two levels of information (in the case of amplitude modulation) are not very distinct and noisy. However, the player’s demodulator is very efficient, based on quadrature synchronous demodulation, it has very good sensitivity. In the case of T2T communication, a fundamental difference is that the detection is here performed by the second tag which is in the vicinity of the reader tag. Consequently, on the one hand, the performance of the receiver (that of a “simple” RFID tag) is much more limited, while the modulated signal is not necessarily at high modulation depth. And on the other hand, the two tags interact. This inter-tag electromagnetic coupling impacts in particular radiation patterns and impedances, and moreover, it depends on the mutual positions of the two tags, more precisely on their antennas (distance separating them, relative orientation, etc.), which leads to high variability the characteristics of the T2T system (and therefore its performance). In addition, there is the impact of the relative position of the external RF source with the pair of tags, which significantly modifies the characteristics of the retro-modulated signals.

The main challenge of the thesis is to determine a framework that can take into account all the factors (signal, component, circuit and system) impacting T2T communication with the aim of evaluating performance, particularly in terms of communication rate. binary error, a metric conventionally used in the field of telecommunications.

Keywords: Backscattering, passive tags, tag to tag communications, UHF RFID

Jury

  • Bergeret Emmanuel Professor Université Clermont Auvergne Reviewer
  • Breard Arnaud Professor Ecole Centrale de Lyon Examiner
  • Lepage Anne-Claire Associate Professor Telecom Paris Examiner
  • Lienard Martine Professor Université de Lille Examiner
  • Vena Arnaud Associate Professor HDR Université de Montpellier Reviewer
  • Villemaud Guillaume Associate Professor HDR INSA-Lyon Thesis director
  • Hutu Florin-Doru Associate Professor INSA-Lyon Co-director
  • Duroc Yvan Professor Université Claude Bernard Lyon 1 Co-director

CITI seminar – Prasenjit Mitra (Penn State) – 13/12 at 10:00

Speaker: Prasenjit Mitra (Penn State)

Date: 13/12/2022

Time: 10h00

Place: Amphi Chappe/Lamarr

Title: Secure Federated Learning: Lessons Learned, and Future Directions

Abstract: In this talk, I will introduce the topic of federated learning and discuss about its implications to computer security and machine learning. Federated learning has a wide range of applications in several areas where machine learning is gaining prominence but the need to preserve privacy arises. For example, hospitals prevented from sharing patient data can nevertheless collaborate to build a better model that utilizes data from multiple hospitals; next generation cars can share their data to enable dynamic, personalized, just-in-time preventive maintenance that can save customers money as well as make cars reliable, while preserving the privacy of individual drivers. The talk will survey the state-of-the-art for the technology, outline several open issues, and briefly mention our previous work on making federated learning solutions robust when adversaries attack. We will also briefly mention issues related to fairness and federated learning and how we can implement explainable and interpretable federated learning. The objective will be to raise questions that are of interest to the community that we can jointly address to improve the state-of-the-art in federated learning with respect to a wide range of attributes, e.g., computational complexity, security, privacy, fairness and equity, robustness, interpretability, etc.

Bio: Prasenjit Mitra is a Professor at The Pennsylvania State University and a visiting Professor at the L3S Center at the Leibniz University at Hannover, Germany. He obtained his Ph.D. from Stanford University in 2003 in Electrical Engineering and has been at Penn State since. His research interests are in artificial intelligence, applied machine learning, natural language processing, etc. His research has been supported by the NSF CAREER award, the DoE, DoD, Microsoft Research, Raytheon, Lockheed Martin, Dow Chemicals, McDonnell Foundation, etc. His has published over 200 peer-reviewed papers at top conferences and journals, supervised or co-supervised 15-20 Ph.D. dissertations; his work has been widely cited (h-index 60) and over 12,500 citations. Along with his co-authors, he has won the test of time award at the IEEE VIS and a best paper award at ISCRAM, etc.


CITI seminar – Alessandro Renzaglia (CITI) – 13/12 at 12:15

Speaker: Alessandro Renzaglia (CR Inria, Chroma)

Date: 13/12/2022

Time: 12h15

Place: Amphi Chappe/Lamarr

Title: Cooperative Exploration for 3D Reconstruction with Multiple Aerial Robots

Abstract: Autonomous exploration of unknown environments is a fundamental task in many robotics applications, such as map reconstruction, search and rescue operations, and inspection tasks. For this reason, it is a widely studied problem and several efficient approaches, for both single and multi-robot systems, have been proposed over the years. However, most of the existing solutions focus on 2D areas, while complex 3D environments still present several problems to be solved. In this talk, I will present some of the challenges of exploring 3D environments with a fleet of cooperating aerial vehicles and discuss different ways to quantify the expected new information contained in unexplored portions of the map and to take into account potential redundancies in the observations. Finally, I will briefly discuss the case, common in inspection tasks, where not all areas to explore are equally informative, but some regions have a higher priority and introduce a search dimension to the classical exploration task.

Bio: Alessandro Renzaglia is a research faculty member in the Chroma team at Inria Lyon / CITI Lab. He received his M.Sc. degree in Physics from the University of Rome La Sapienza, Italy, and his Ph.D. degree in Computer Science from the University of Grenoble, France. Successively he has been Postdoctoral Researcher with the Computer Science & Engineer Department at the University of Minnesota, Minneapolis, USA, and later with the Laboratory for Analysis and Architecture of Systems (LAAS), Toulouse, France, in the Robotics and Interactions group, before to join the Chroma team. His main research interests include multi-robot systems, path planning, and optimization.


CITI seminar – Anastasia Volkova (Univ. Nantes) and Florent de Dinechin (CITI) – 08/11 at 12:15

Title: Reconciling LTI filters and their implementations

Date and Place: 12h15 Tuesday 08/11/2022 in Amphi Hedy Lamarr/Chappe

Speaker: Anastasia Volkova (Univ. Nantes) and Florent de Dinechin (CITI)

 

Abstract: 

Linear time-invariant (LTI) filters are widely used in digital signal processing (DSP). Such filters can be designed out of a frequency specification (amplify some frequency bands, attenuate others), and a wide body of techniques exist to transform such a specification into an actual implementation consisting of additions and multiplications. The linearity property (the L of LTI) is essential at all the steps of this design process. However, actual implementations in hardware or software cannot be linear, due to the rounding of intermediate results: rounding is necessary to keep the result of a multiplication on the same number of bits as its inputs. But rounding is not linear, for instance the function that rounds a real to the nearest integer is not linear. So implementations of LTI filters are actually not linear, and this loss of linearity destroys in principle most mathematical foundations on which they are built. The workaround found by the DSP community so far is quite simple: ignore the problem, and hope for the best. Most of the times it works, and indeed your mobile phone is full of such filters. When it doesn’t, strange (and sometimes catastrophic) things will happen, and the community has devised all sorts of tricks and patches to evade them.

This talk will first present a gentle (but incomplete) introduction to LTI filters, their design, and the issue of non-linearity. It will then introduce a simple formalization that reconciles LTI filters and their
implementations. An additional benefit of this unified view is that filter design and implementation becomes a well-formed single global optimisation problem. The talk will conclude with the latest developments towards solving this problem.

Bio:

Anastasia Volkova est maître de conférences à l’Université de Nantes et membre de l’équipe OGRE au LS2N. Avant de commencer à Nantes en 2019, elle a été chercheuse postdoctorale à Intel San Diego, au Max-Plank Institute à Saabrucken, et à l’Inria à Lyon. Dans sa recherche elle se focalise sur des problématiques de précision finie dans des applications numériques, notamment l’analyse d’erreurs, mais aussi sur le compromis entre la précision et la performance. Elle s’intéresse en particulier à la conception et à l’implémentation logicielle ou matérielle des filtres LTI avec garantie de qualité  numérique, et à l’optimisation des ressources matérielles, e.g. sur FPGA.

Florent de Dinechin est professeur à l’INSA-Lyon après un doctorat de l’Université of Rennes-1 en 1997, un post-doctorat à Imperial College à Londres, et un premier poste à l’École Normale Supérieure de Lyon. Il s’intéresse à l’arithmétique des ordinateurs dans ses aspects mathématiques, matériels et logiciels, et particulièrement aux fonctions élémentaires, à la virgule flottante, et à l’arithmétique pour les FPGA.


PhD Defence: “Symmetric semi-discrete optimal transport for mesh interpolation”, Agathe Herrou, C5 room, Nautibus building, 20th of October 2022 at 1.30 PM

 

The defenseIt will take place on Thursday 20th october at 1:30 PM in the C5 room of the Nautibus building, Villeurbanne.

 

Title

Symmetric semi-discrete optimal transport for mesh interpolation

 

 

Abstract

This thesis aims to develop geometric methods to approximate displacement interpolation, derived from optimal transport. Optimal transport is a mathematical theory modeling movements of matter under a cost minimization constraint, with many applications in physics, computer graphics and geometry. The minimum displacement cost between two distributions defines a distance, which itself is at the origin of displacement interpolation. This interpolation may under certain conditions present discontinuities, that the discretized approximations of the optimal transport do not always successfully capture. The work of this thesis aims to develop an approximation that captures these discontinuities well. Our method relies on semi-discrete optimal transport, where only one of the distributions is discretized, thus accurately capturing the discontinuities of the distribution that remains continuous. The transport plans thus obtained partition the continuous distribution into cells associated with the samples of the discretization. A semi-discrete optimal transport plan can thus be assimilated to a power diagram made up of these cells. This variant of optimal transport however has the disadvantage of breaking the symmetry between the two distributions. We start by formalizing our problem as the search for a pair of transport plans coupled through the barycenters of their cells. We then present an algorithm for calculating these coupled transport plans. This first algorithm is based on a classical alternating algorithm scheme, successively computing the transport plans and the barycenters of their cells until convergence. The results obtained from this algorithm allow to interpolate between the initial distributions while maintaining a satisfactory precision, in particular when it comes to discontinuities, including when the discretization of the distributions is done with relatively few points. We then present our exploration of optimization methods for solving the same problem. These methods express the constraints of our problem as a critical point of a functional, and aim to reach these points using algorithms such as Newton’s method. However, this approach did not yield conclusive results, as the functions involved were too noisy to lend themselves well to optimization algorithms.

Keywords: Optimal transport, Interpolation, Optimization, Algorithmic geometry

Jury

    • Julie Delon (reviewer), Université Paris Cité
    • Boris Thibert (reviewer), Université Grenoble Alpes
    • Dominique Attali (examiner), CNRS/Université Grenoble Alpes
    • Filippo Santambrogio (examiner), Université Lyon 1
    • Nicolas Bonneel (advisor), CNRS/Université Lyon 1
    • Julie Digne (co-advisor), CNRS/Université Lyon 1
    • Bruno Lévy (co-advisor), Inria Nancy Grand Est