scispace - formally typeset
Search or ask a question
Author

Bérengère Lebental

Bio: Bérengère Lebental is an academic researcher from École Polytechnique. The author has contributed to research in topics: Carbon nanotube & Graphene. The author has an hindex of 9, co-authored 54 publications receiving 387 citations. Previous affiliations of Bérengère Lebental include Université Paris-Saclay & Centre national de la recherche scientifique.


Papers
More filters
Journal ArticleDOI
01 Dec 2015-Carbon
TL;DR: In this paper, the reproducibility of the sensitivity, the most critical parameter for sensing application, has been only marginally assessed for carbon nanotube networks (CNNs) based resistive strain sensors fabricated by inkjet-printing on flexible Ethylene Tetrafluoroethylethylene (EFTE) sheets.

100 citations

Journal ArticleDOI
TL;DR: A taxonomy of the methodologies in the literature is proposed, which relies on both the architecture of the network of sensors and the algorithmic principles of the calibration methods, and focuses on in situ calibration methods for environmental sensor networks.
Abstract: The recent developments in both nanotechnologies and wireless technologies have enabled the rise of small, low-cost and energy-efficient environmental sensing devices. Many projects involving dense sensor networks deployments have followed, in particular, within the Smart City trend. If such deployments are now within economical and technical reach, their maintenance and reliability remain, however, a challenge. In particular, reaching, then maintaining, the targeted quality of measurement throughout deployment duration is an important issue. Indeed, factory calibration is too expensive for systematic application to low-cost sensors, as these sensors are usually prone to drifting because of premature aging. In addition, there are concerns about the applicability of factory calibration to field conditions. These challenges have fostered many researches on in situ calibration. In situ means that the sensors are calibrated without removing them from their deployment location, preferably without physical intervention, often leveraging their communication capabilities. It is a critical challenge for the economical sustainability of networks with large-scale deployments. In this paper, we focus on in situ calibration methods for environmental sensor networks. We propose a taxonomy of the methodologies in the literature. Our classification relies on both the architecture of the network of sensors and the algorithmic principles of the calibration methods. This review allows us to identify and discuss two main challenges: how to improve the performance evaluation of such methods and how to enable a quantified comparison of these strategies?

41 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present the design of a novel Ground Penetrating Radar (GPR) test site that has been integrated into the mini-city demonstrator Sense-City located at University Paris-Est (France).

36 citations

Journal ArticleDOI
01 Jun 2018-Carbon
TL;DR: In this article, the authors proposed a novel three dimensional CNT (3D CNT) network structure, where VACNTs are cross-linked by randomly-oriented secondary CNTs.

29 citations

Journal ArticleDOI
TL;DR: This work demonstrates the large-area formation of continuous transparent graphene layers at temperatures as low as 450 °C using a plasma-enhanced chemical vapour deposition process, and measures the optical transmittance of the layers without any transfer.
Abstract: Post-growth transfer and high growth temperature are two major hurdles that research has to overcome to get graphene out of research laboratories. Here, using a plasma-enhanced chemical vapour deposition process, we demonstrate the large-area formation of continuous transparent graphene layers at temperatures as low as 450 °C. Our few-layer graphene grows at the interface between a pre-deposited 200 nm Ni catalytic film and an insulating glass substrate. After nickel etching, we are able to measure the optical transmittance of the layers without any transfer. We also measure their sheet resistance directly and after inkjet printing of electrical contacts: sheet resistance is locally as low as 500 Ω sq-1. Finally the samples equipped with printed contacts appear to be efficient humidity sensors.

24 citations


Cited by
More filters
01 May 1993
TL;DR: Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems.
Abstract: Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

29,323 citations

Journal ArticleDOI
TL;DR: This paper reviews the latest development of the GPR’s primary infrastructure applications, namely buildings, pavements, bridges, tunnel liners, geotechnical and buried utilities and outlines the path to a more rigorous development in terms of standardization, accreditation, and procurement policy.
Abstract: The GPR (Ground Penetrating Radar) conference in Hong Kong year 2016 marked the 30th anniversary of the initial meeting in Tifton, Georgia, USA on 1986. The conference has been being a bi-annual event and has been hosted by sixteen cities from four continents. Throughout these 30 years, researchers and practitioners witnessed the analog paper printout to digital era that enables very efficient collection, processing and 3D imaging of large amount of data required in GPR imaging in infrastructure. GPR has systematically progressed forward from “Locating and Testing” to “Imaging and Diagnosis” with the Holy Grail of ’Seeing the unseen’ becoming a reality. This paper reviews the latest development of the GPR’s primary infrastructure applications, namely buildings, pavements, bridges, tunnel liners, geotechnical and buried utilities. We review both the ability to assess structure as built character and the ability to indicate the state of deterioration. Finally, we outline the path to a more rigorous development in terms of standardization, accreditation, and procurement policy.

293 citations

Journal ArticleDOI
TL;DR: In this article, an ultrathin epitaxial graphite graphite (NPEG) was grown by thermal decomposition on the (0001) surface of 6H-SiC and characterized by surface-science techniques.
Abstract: We have produced ultrathin epitaxial graphite films which show remarkable 2D electron gas (2DEG) behavior. The films, composed of typically 3 graphene sheets, were grown by thermal decomposition on the (0001) surface of 6H-SiC, and characterized by surface-science techniques. The low-temperature conductance spans a range of localization regimes according to the structural state (square resistance 1.5 kOhm to 225 kOhm at 4 K, with positive magnetoconductance). Low resistance samples show characteristics of weak-localization in two dimensions, from which we estimate elastic and inelastic mean free paths. At low field, the Hall resistance is linear up to 4.5 T, which is well-explained by n-type carriers of density 10^{12} cm^{-2} per graphene sheet. The most highly-ordered sample exhibits Shubnikov - de Haas oscillations which correspond to nonlinearities observed in the Hall resistance, indicating a potential new quantum Hall system. We show that the high-mobility films can be patterned via conventional lithographic techniques, and we demonstrate modulation of the film conductance using a top-gate electrode. These key elements suggest electronic device applications based on nano-patterned epitaxial graphene (NPEG), with the potential for large-scale integration.

290 citations

Journal ArticleDOI
TL;DR: A broad range of challenges faced by the construction industry, ranging from the performance of the materials to environmental and safety issues, relate to materials and their properties, and recent developments in various areas of nanotechnology show significant promise in addressing many of these challenges as discussed by the authors.

255 citations

Journal ArticleDOI
TL;DR: In this paper, a review article concentrates on analyzing the articles on thermal conductivity of CNT networks and summarizes the results obtained using those techniques, such as the 3-ω method, bolometric, steady-state method and their variations, hot-disk method, laser flash analysis, thermoreflectance method and Raman spectroscopy.
Abstract: Depending on their structure and order (individual, films, bundled, buckypapers, etc.), carbon nanotubes (CNTs) demonstrate different values of thermal conductivity, from the level of thermal insulation with the thermal conductivity of 0.1 W/mK to such high values as 6600 W/mK. This review article concentrates on analyzing the articles on thermal conductivity of CNT networks. It describes various measurement methods, such as the 3-ω method, bolometric, steady-state method and their variations, hot-disk method, laser flash analysis, thermoreflectance method and Raman spectroscopy, and summarizes the results obtained using those techniques. The article provides the main factors affecting the value of thermal conductivity, such as CNT density, number of defects in their structure, CNT ordering within arrays, direction of measurement in relation to their length, temperature of measurement and type of CNTs. The practical methods of using CNT networks and the potential directions of future research in that scope were also described.

219 citations