Salotti J.-M.,IMS Laboratory |
Koppel C.,KopooS Consulting Ind.
Proceedings of the International Astronautical Congress, IAC | Year: 2016
For the design of manned missions to Mars, a difficult problem is the choice of the propulsion system for interplanetary transfer between Earth and Mars. Recent studies suggest the use of solar electric propulsion systems (Drake et al, Raftery et al) while others are still based on chemical propulsion (Salotti). A review of the different benefits and drawbacks is proposed. SEP is particularly appropriate for cargos that can be sent to Mars in advance without time constraints. Chemical propulsion is best suited for a manned vehicle if the duration of the trip has to be minimized, e.g. less than 6 months. Beyond these well-known considerations, other parameters are discussed. An important finding is that aerocapture allows important mass savings and makes chemical based interplanetary transportation competitive with SEP, especially for Mars landing vehicles. On the other hand, the SEP option allows more flexible departure strategies. Another idea is to use both chemical and solar electric propulsion. In the first part of the mission, all modules are sent to a high Earth orbit by means of SEP, for instance the Earth Moon lagrangian point. Once assembled, a small chemical propulsion system or kick stage is used for a quick escape of the gravity well. The efficiency of the maneuver can eventually be improved by means of an Earth flyby. SEP is then used for the remaining part of the interplanetary travel. The duration of the trip is nevertheless still longer than with chemical propulsion only and the mission remains complex, especially for the manned trip. An important parameter of the problem is the number of crew. With 3 astronauts, it is shown that the all chemical option with aerocapture is competitive in terms of IMLEO and much simpler than the SEP one. With a larger crew, the number of heavy launches quickly increases. SEP becomes much more interesting for the cargos but chemical propulsion might still be preferred for the manned vehicle in order to speed up the interplanetary transit. Copyright 2016 by Prof. Jean-Marc Salotti.
Chan Wai Po F.,CEA Grenoble |
De Foucauld E.,CEA Grenoble |
Morche D.,CEA Grenoble |
Vincent P.,CEA Grenoble |
Kerherve E.,IMS Laboratory
IEEE Transactions on Circuits and Systems I: Regular Papers | Year: 2011
We present a novel method simplifying matching network synthesis and design based on a tunable low-pass π matching network topology. This method exploits the Smith chart in a novel way. Analytic expressions for calculating the optimal matching network for automatically adapting the load to the source impedance are derived. This work is applied to a new antenna tuning unit concept able to calibrate the system in a single iteration process reducing strongly both the speed and the overall consumption of the antenna calibration module. The obtained matching network nodal and load quality factors are analyzed and the matching network efficiency is evaluated to highlight the impact of the imperfection in the design. The simulation and experimental results are presented to validate the proposed method and to evaluate the obtained matching efficiency. We perform reflection coefficients less than-dB, high efficiency matching networks with only 258 μs to calculate the proper state of the tunable matching network under a processor delivering 40 MIPS of performance. © 2011 IEEE.
Polyaniline/clay as nanostructured conductive filler for electrically conductive epoxy composites. Influence of filler morphology, chemical nature of reagents, and curing conditions on composite conductivity
Oyharcabal M.,Research Company |
Olinga T.,Research Company |
Foulc M.-P.,Research Company |
Vigneras V.,IMS Laboratory
Synthetic Metals | Year: 2012
Electrically conductive composites based on epoxy resin, anhydride hardener and polyaniline (PANI) as conductive filler have been formulated and characterized. Standard PANI (Pani) and PANI/clay (PANICN) nanofillers were used to study the impact of filler morphology on the electrical properties of composites. Clay was used as a nanostructured template to increase the PANI aspect ratio (ratio of length to diameter or thickness). The use of PANICN reduces the electrical percolation threshold of composites from 4.5 vol.% to 1.3 vol.%. Moreover, the conductivity of composites containing PANICN is improved to values superior to 10 -3 S/cm. The effects of reagents and curing conditions were also evaluated. It was demonstrated that a classical alkaline curing accelerator, such as imidazole, exhibits chemical incompatibilities with the PANI conductive form, resulting in less conductive composites. Substituting the classical alkaline curing accelerator with a cationic accelerator, such as a Lewis acid, is a promising alternative to obtain conductive epoxy composites with a low content of PANI. © 2012 Elsevier B.V. All rights reserved.
Oyharcabal M.,Research Company |
Olinga T.,Research Company |
Foulc M.-P.,Research Company |
Lacomme S.,French Institute of Health and Medical Research |
And 2 more authors.
Composites Science and Technology | Year: 2013
This study reports on the electrical conductivity and dielectric properties of conductive epoxy composites containing polyaniline (PANI) with various morphologies. Globular, fibrillar, and flake-like PANIs, with more or less high aspect ratios (ratio of length to diameter or thickness), were synthesized and dispersed into an epoxy resin. It was found that increasing the aspect ratio of PANI reduces the electrical percolation threshold of the composites (from 3.9 to 1.3vol.%), and enhances their electrical conductivity up to σ>10-3S/cm. Moreover, it was found that flake-like PANI, with increased aspect ratio, improves the microwave absorption properties of the composites in a microwave range: 2.4-8.8GHz. The imaginary permittivity (ε'') was doubled for composites containing flake-like PANI, compared to globular and fibrillar PANI. These higher values of dielectric losses have been attributed to the highly polarizable structure of flake-like PANI, which contributes to more important polarization mechanisms. © 2012 Elsevier Ltd.
Mangas A.,Institute of Neurosciences of Castilla and Leon INCYL |
Covenas R.,Institute of Neurosciences of Castilla and Leon INCYL |
Geffard M.,IMS Laboratory
Current Opinion in Neurology | Year: 2010
PURPOSE OF REVIEW: Multiple sclerosis (MS) is an autoimmune and inflammatory disease of the central nervous system (CNS) that causes neurological disability in young adults and that to date has no cure. Until now, expensive and only partially efficacious therapies have become available. For this reason, researchers, clinicians and pharmaceutical companies are currently investigating new drugs for the treatment of MS. Here, we review the most recent data on drug candidates for MS. RECENT FINDINGS: In the preclinical phase, such drug candidates have shown a beneficial effect on the onset of experimental autoimmune encephalomyelitis (microtubule-stabilizing drugs, MS14, Lithium, GEMSP⋯), a decrease in CNS cell infiltrates (recombinant T cell receptor ligand, lovastatin-rolipram, ribavirin, GEMSP⋯), prevention of demyelination (lovastatin-rolipram, calpain inhibitor, lithium⋯); and a reduction of axonal loss (phenytoin, lovastatin-rolipram, calpain inhibitor). In clinical trials, drug candidates against MS have shown safety (rituximab, ustekinumab, intravenous immunoglobulin, laquinimod, BHT-3009, fumarate, chaperonin 10, GEMSP⋯), an improvement of gadolinium-enhanced lesions (protiramer, fingolimod, laquinimod, BHT-3009, fumarate, daclizumab⋯), and an improvement of the relapse rate (fingolimod, fumarate⋯). SUMMARY: Future research into MS should focus on a combination of therapies and on the development of drugs directed against the remitting and progressive phases of the disease. In this sense, MS is a very complex multifactorial disease that requires treatment able to cover all the aspects of MS and not only the anti-inflammatory aspect. © 2010 Lippincott Williams & Wilkins.
Sabatier J.,French National Center for Scientific Research |
Lanusse P.,IMS Laboratory |
Feytout B.,VALEOL |
Control Engineering Practice | Year: 2016
This paper presents an application of CRONE control, a robust control based on fractional order differentiation, to an anti-icing/deicing system for wind turbine blades. The deicing system uses an electrically conductive polymer paint applied on the blade at ice formation areas. The voltage applied to the paint leads to its heating. Based on a temperature measure provided by various sensors placed on the blade, a control system can thus be used to prevent the blade icing up during wind turbine operation or to deice the blade after a rest time. To design the control system, a thermal model of the blade with the paint was developed and its associated parameters were identified using tests in a climatic wind tunnel. A CRONE controller was then designed and its performance evaluated both on blade subparts in the climatic wind tunnel and on a floor-standing real blade. © 2016 Elsevier Ltd.
Wannous H.,IMS Laboratory |
Lucas Y.,University of Orléans |
Treuillet S.,University of Orléans
IEEE Transactions on Medical Imaging | Year: 2011
With the widespread use of digital cameras, freehand wound imaging has become common practice in clinical settings. There is however still a demand for a practical tool for accurate wound healing assessment, combining dimensional measurements and tissue classification in a single user-friendly system. We achieved the first part of this objective by computing a 3-D model for wound measurements using uncalibrated vision techniques. We focus here on tissue classification from color and texture region descriptors computed after unsupervised segmentation. Due to perspective distortions, uncontrolled lighting conditions and view points, wound assessments vary significantly between patient examinations. The main contribution of this paper is to overcome this drawback with a multiview strategy for tissue classification, relying on a 3-D model onto which tissue labels are mapped and classification results merged. The experimental classification tests demonstrate that enhanced repeatability and robustness are obtained and that metric assessment is achieved through real area and volume measurements and wound outline extraction. This innovative tool is intended for use not only in therapeutic follow-up in hospitals but also for telemedicine purposes and clinical research, where repeatability and accuracy of wound assessment are critical. © 2010 IEEE.
Gheorghe A.,IMS Laboratory |
Zolghadri A.,University of Bordeaux 1 |
Cieslak J.,University of Bordeaux 1 |
Goupil P.,Airbus |
And 2 more authors.
IEEE Control Systems | Year: 2013
Many innovative solutions have been developed by the aeronautical sector toward achieving the future ?sustainable? aircraft that will be cleaner, quieter, smarter, and more affordable. Weight reduction is one of the most significant contributors to sustainability, as it improves aircraft performance (fuel consumption, noise, range) and consequently decreases its environmental footprint. Since the 1980s, the electrical flight controls system (EFCS), also known as fly-by-wire (FBW), introduced by Airbus on civilian aircraft , , has been a weight-saving technology in which the conventional heavy mechanical linkages between the pilot?s inputs and the control surface actuators were replaced by lighter electrical signal wires and digital flight control computers (FCCs). More recently, the electro-hydrostatic actuators introduced on the A380  allowed the replacement of three conventional hydraulic circuits by two hydraulic circuits plus two electric layouts, which resulted in a weight savings of about 1 ton of mass for the aircraft. For future aircraft, the next important issue is the structural design optimization, which will result in lighter, and therefore greener, aircraft. However, this design improvement leads to increased interactions between EFCS failures and structural loads. Therefore, structural optimization must be properly accompanied by advanced fault detection and diagnosis (FDD) techniques for limiting the impacts of flight control system failures. Highlighting the link between aircraft sustainability and fault detection, it can be demonstrated that improving the performance of FDD allows designers to further optimize the aircraft structural design, which in turn leads to further weight reduction. © 1991-2012 IEEE.
Vacar C.,IMS Laboratory |
Giovannelli J.-F.,IMS Laboratory |
Berthoumieu Y.,Bordeaux Polytechnic Institute
IEEE Signal Processing Letters | Year: 2014
This letter addresses an estimation problem based on blurred and noisy observations of textured images. The goal is jointly estimating the 1) image model parameters, 2) parametric point spread function (semi-blind deconvolution) and 3) signal and noise levels. It is an intricate problem due to the data model non-linearity w.r.t. these parameters. We resort to an optimal estimation strategy based on Mean Square Error, yielding the best (non-linear) estimate, namely the Posterior Mean. It is numerically computed using a Monte Carlo Markov Chain algorithm: Gibbs loop including a Random Walk Metropolis-Hastings sampler. The novelty is double: i) addressing this fully parametric threefold problem never tackled before through an optimal strategy and ii) providing a theoretical Fisher information-based analysis to anticipate estimation accuracy and compare with numerical results. © 2014 IEEE.
Gros J.-B.,IMS Laboratory |
Duchamp G.,IMS Laboratory |
Levant J.-L.,Atmel Corporation
Proceedings of EMC Europe 2011 York - 10th International Symposium on Electromagnetic Compatibility | Year: 2011
This paper presents the relevance of using VHDL-AMS language to achieve EMC models for integrated circuits. After an introduction about the EMC estimation, we present an emissivity model of a FLASH MEMORY using VHDL-AMS. More precisely, we illustrate the design of the Internal Activity model to predict parasitic emissions. In a third part, we expose a VHDL-AMS immunity model of an ADC circuit. Finally, the relevance of VHDL-AMS is pointed out in the whole methodology. © 2011 EMC Europe.