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Poster: A microarchitectural signals analysis platform to craft Hardware Security Counters
No full textInternational audienceDetecting malicious software or hardware behavior during the operation of a computer system requires observables from one or more abstraction layers of the system. However, this abstraction tends to limit the ability to detect behavioral deviations, especially for attack classes that exploit vulnerabilities very close to the target hardware. Conversely, too low a level of abstraction tends to significantly increase the complexity of the system model, and therefore poses a number of difficulties for the extraction and selection of relevant observables for a given class of attack. In particular, processor performance counters have been used as an indirect means of observing microarchitecture behavior and detecting software attempting to exploit hardware vulnerabilities. In order to improve the various detection methods, we propose the construction of hardware metrics designed from the outset for security, by studying the correlation between signals from the microarchitecture and the various classes of attack in the literature, targeting both usual and industrial systems. By extension, this work aims to detect attacks originating from hardware Trojans, the latter having the effect of changing the behavior of a given microarchitecture
Recent Challenges in the Fabrication of Vertical Silicon Nanowire Transistors
No full textInternational audienceVertical silicon nanowire transistors are among the most promising device concepts for future low-power electronics due to their gate-all-around nature as well as their 3D stacking potential. In this work we review the current status of transistor fabrication on vertical silicon nanostructures and identify the most important challenges for successful process integration. Channel patterning, source/drain contact formation, gate-deposition and spacer engineering are identified as key steps independent on the actual process integration sequence. We conclude the paper with two emerging device examples and discuss the influence of the processing challenges on the transistor design
Towards Canonical and Minimal Solutions in a Constraint-based Plan-Space Planner
No full textInternational audienceTemporal planning is the problem of selecting and scheduling a set of actions in order to achieve a distant objective from an initial state. Constraint Programming (CP) has historically played an important role in many automated temporal planners based on the Plan-Space Planning (PSP) algorithm. In a nutshell, PSP would drive the search for a plan by selecting which actions to add and how to resolve conflicts, with an embedded CP engine in charge of ensuring the coherence of the plan.In this paper, we consider an existing encoding of temporal planning into constraint programming that adheres to a plan-space approach, but encodes the decision of the PSP algorithm as decision variables of the CSP, thus letting the CP engine entirely drive the search for a solution plan. Analyzing the encoding, we show that the induced search space contains many symmetries that would be absent from the original PSP algorithm. Another caveat of the encoding is that it allows for non-minimal solutions, i.e., solutions in which some actions may be removed without invalidating it.We propose to extend the encoding with additional symmetry breaking constraints to enforce canonicity of the considered plans. The encoding is further improved with additional constraints to limit the presence of non-minimal plans. We show the extended encoding to very substantially improve the performance of the original version and to be competitive with state-of-the-art state-space temporal planners on the considered benchmarks
Brillouin-induced Kerr frequency comb in normal dispersion fiber Fabry Perot resonators
No full textThis work was supported by the Agence Nationale de la Recherche (Programme Investissements d’Avenir, FARCO and VISOPEC projects (A.M.)); Ministry of Higher Education and Research; European Regional Development Fund (Photonics for Society P4S, (A.M., M.C. and A.K.)) and the CNRS (IRP LAFONI, (A.M.)) and H2020 Marie Skłodowska-Curie Actions (FRESCOS, (A.M.)), Royal Academy of Engineering (EPSRC Project EP/W002868/1 (A.M.))International audienceWe report the generation of a stable, broadband frequency comb, covering more than 10 THz, using a dispersion fiber Fabry-Perot resonator with a high quality factor of 69 millions. This platform ensures robust and easy integration into photonic devices via FC/PC connectors, and feature quality factors comparable to those of microresonators. We demonstrate a passive mode-locking phenomenon induced by the coherent interaction of the Kerr effect and Brillouin scattering, which generates a frequency comb with a repetition rate exceeding the free spectral range of the cavity. This parametric process modulates the continuous wave (CW) pump and can then be transformed into a train of almost square-wave pulses thanks to the generation of switching waves. Our results are supported by advanced numerical simulations, and theoretical derivations that include the Brillouin effect in the Fabry-Perot configuration. The very high stable feature of this optical frequency comb lying in the GHz range is critical to several applications ranging from telecommunication, spectroscopy and advanced microwave generation.High quality factor nonlinear Kerr cavities have been instrumental in generating broadband and highly stable frequency combs, with operational repetition rate ranges ranging from MHz to THz 1,2 . These combs are crucial for a variety of applications, such as high bit rate modern telecommunications 3 , high-precision spectroscopy 4 , ultraprecise distance ranging 5 , and low noise microwave generation 6,7 , as highlighted in recent reviews 8-10 . The characteristics of optical frequency combs (OFCs) for each application depend largely on the dispersion regime of the cavity. The most widespread phenomenon in this context are bright cavity solitons 11-13 , predominantly because they facilitate broadband frequency combs, even enabling self 2f-3f self referencing schemes 14 . The latter exist in the anomalous dispersion regime. In the normal dispersion region, dark and gray solitons can be excited 3,15-19 . These solitons, forming through the connection of two switching waves (SW) 20 , produce narrower but flatter comb spectra, and offer higher pump power conversion efficiency compared to bright soliton configurations. In all these setups, Stimulated Brillouin Scattering (SBS) effect is typically avoided, either by employing pulsed pumps with durations shorter than the characteristic SBS coherence time (the phonon lifetime is typically 20 ns in silica 21 ), or by designing cavities with a sufficiently large free spectral range (FSR) for the SBS gain to lie just between consecutive cavity resonances, thus preventing SBS build-up. Another approach consist in stimulating this effect to exploit its high gain to generate frequency combs in resonators. In this case, CW lasers are used as pumps, and the cavities are designed so that the SBS can resonate by matching the FSR or a multiple of the FSR with the frequency offset of the SBS (typically 10 GHz in Silica 21 ). This is successfully achieved in microresonators with dimensions of about a centimeter to reach a FSR of about 10-11 GHz 22-25 , or in slightly longer resonators to to match with higher order resonances 26,27
Synthesis of Si@Au core-shell particles for directional light scattering
No full textInternational audienc
Diode PIN verticale sur diamant (100) autosupporté à base de couches i et n dopées phosphore
No full textNational audienceCet article présente la réalisation et la caractérisation de diodes bipolaires n + -i-p + en diamant sur substrat autosupporté (100) caractérisées électriquement jusqu'à 600 °C sous vide à l'aide d'un équipement unique en France. Les résultats obtenus mettent en évidence la faisabilité et les performances prometteuses des diodes PIN en diamant pour des applications en électronique de puissance
Metaheuristic methods for the VRP with shared deliveries in short food supply chains
No full textInternational audienceThis study explores the logistical challenges faced by Short Food Supply Chains (SFSC), where producers often encounter high transportation costs due to fragmented deliveries and limited economies of scale. To address this challenge, a new variant of the Vehicle Routing Problem (VRP) is proposed, allowing producers to collaborate by sharing deliveries with partner producers. In this model, a producer can either drop off goods with a partner who will complete the delivery or pick up goods from a partner to deliver them along their own route. This mutualization strategy aims to enhance efficiency while reducing logistical cost
