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Classical and relativistic balance of configurational forces
No full textInternational audienceThis article develops a unified variational framework for configurational (or material) forces in both Classical (3D, non-relativistic) and Relativistic (4D) Continuum Mechanics. Configurational forces describe the evolution of material defects-such as cracks, dislocations, and interfaces-which move relative to the material rather than through physical space. In the classical setting of hyperelasticity, the authors revisit the balance of configurational forces using an intrinsic Lagrangian formulation, where the material body is modeled as an abstract three-dimensional manifold. By treating the reference configuration as a variable and performing a Lagrangian variation with respect to it, they show that the configurational forces balance naturally emerges. Importantly, this balance equation is not independent: it is equivalent to the standard balance of linear momentum combined with constitutive relations, and it is expressed through the Eshelby stress tensor on the reference configuration. The framework is then extended to Relativistic Hyperelasticity within General Relativity. Matter is described by a matter field, a vector valued function, defined on the four-dimensional Universe, and the Lagrangian (i.e., Action) includes both matter and gravitational contributions. Two stress-energy tensors arise: the Noether stress-energy tensor (from variations with respect to the matter field) and the Hilbert stress-energy tensor (from variations with respect to the Universe metric). Assuming General Covariance, the authors prove that these tensors and their associated balance laws are equivalent. By introducing the notion of an observer and specializing to static spacetimes, the authors define a relativistic generalization of the deformation and derive a four-dimensional Eshelby tensor. They show that in Special Relativity, as in Classical Continuum Mechanics, the relativistic configurational forces balance is not a new equation but follows from the conservation laws of the Noether stress-energy tensor. Finally, they recover the classical configurational forces balance as the non-relativistic limit of the relativistic theory. Overall, the paper provides a rigorous geometric and variational interpretation of configurational forces, unifying classical and relativistic formulations and clarifying their deep connection with standard equilibrium equations.</div
Expressing the weighting factor with Planck function in the wide-band based WSGG model
No full textInternational audienceThe weighting factor is expressed from Planck function in the wide-band based WSGG model, which provides a more physically meaningful formulation. The pressure absorption coefficient is expressed with a quadratic polynomial function of the normalized temperature. An objective function based on the combined errors of S r and Q r allows achieving a good accuracy both on these two quantities. A new method is proposed to determine an optimal spectrum partitioning and a genetic algorithm is used to determine the model parameters based on LBL and HITEMP 2010 data. The full spectrum is subdivided into 6 bands and using 1 gray gas per band, the new model is applied to non-isothermal and non-homogeneous CO 2 -H 2 O mixtures with black walls, mole fraction ratios (H 2 O to CO 2 ) R equal to 1 and 2, over a temperature range from 300 K to 3,000 K, and at atmospheric pressure. Over 92 test cases and for both R = 1 and R = 2, the maximum normalized errors on S r and Q r are below 6.9% and 5% respectively, while the corresponding average errors are below 3.7%. Nomenclature a kWeighting factor of the k-th gray gas b k,i Polynomial coefficient of index i associated with κ p,k for the k-th gray gas ε max SrMaximum normalized error of S r , dimensionless</div
Influence of Fe-Rich Materials on the Evolution of Amino Acids under Asteroidal Aqueous Alteration
No full textInternational audienceAmino acids have been detected in carbonaceous chondrites, with abundances and isotopic compositions varying significantly between different meteorites as well as within individual meteorites. In this study, we assessed whether the presence and abundance of Fe-rich phases during parent body alteration can account for observed variations in amino acid concentrations and isotope composition. To test this, we examined the chemical and 13C-isotopic signatures of six amino acids–glycine, β-alanine, α-alanine, 2-aminoisobutyric acid, γ-aminobutyric acid, and isovaline–following experimental exposure to hydrothermal conditions (150°C, 10 days) in the presence or absence of Fe-bearing materials (Fe, Fe2O3, FeS2). In the absence of Fe-rich materials, glycine and α-alanine rather withstood hydrothermal conditions, consistently with abundances reported for carbonaceous chondrites having experienced various degrees of aqueous alteration. In contrast, upon exposure to similar hydrothermal conditions, the degradation of β-alanine produced a new compound, possibly 3-aminoadipic acid, via the recombination of products of its decarboxylation and deamination, while more than 95% of γ-aminobutyric acid was converted to 2-pyrrolidone through self-cyclization. The presence of Fe-rich materials inhibited the destruction of β-alanine, 2-aminoisobutyric acid, and γ-aminobutyric acid. Fe2O3 promoted the conversion of glycine into aspartic acid, and the resulting organics interacted with Fe2O3, leading to a relatively higher organic content in the residues compared to other Fe-containing materials after the experiments. Oxides in CI chondrites may exhibit variable effects on each amino acid compound during aqueous alteration, potentially explaining the higher β-Alanine/Glycine ratios observed compared with CM chondrites. The slight changes in δ13C values of amino acids upon exposure to hydrothermal conditions, independent of the presence or absence of Fe-rich materials, could not account for the variations observed in the δ13C values of chondritic amino acids. Hence, the δ13C values of amino acids reported in CR and CM chondrites may be inherited from the preaccretion processes
Stroke Research Projects at Empenn: Invited Seminar, MIND Team (INRIA, CEA, Neurospin)
No full textInvited Seminar, MIND Team (INRIA, CEA, Neurospin
Effects of an unsynchronized RTS attack on a hardware 802.11ah test bed
No full textInternational audienceWi-Fi HaLow is expected to play a pivotal role inIoT 2.0; however, its increasing adoption makes it an attractivetarget for cyber adversaries. Enabling more than 8,000 deviceson a single deployment, Wi-Fi HaLow awakens the possibility ofmassive network creation along 1 km distances. Unfortunately,attackers can easily take advantage of this extensive reach.Current research shows how an RTS attack, a MAC sub-layerattack, can shut down the communication exchange of an entireWi-Fi HaLow network, yet no real test bed implementation hasbeen done. This is the first article that studies the effects of anunsynchronized RTS attack on a hardware-implemented Wi-FiHaLow network. The results show that the STA can not detectthe attack based on the metrics and the attack has an impact of95.7% at the physical layer and a 4.3% at the MAC sub-layer
Deception Detected: An Empirical Study of SSH Honeypot Detection and Fingerprinting in a Capture-the-Flag Competition
No full textThe effectiveness of cyber deception technologies relies on their ability to remain indistinguishable from production systems under adversarial scrutiny. Consequently, this paper presents an empirical study of SSH honeypot detection techniques observed during a high-interaction honeypot challenge deployed in the qualification phase of the European Cyber Week (ECW) Capture-the-Flag (CTF) competition. The challenge was designed to log and analyze the methods used by hackers to distinguish a simulated SSH service from a genuine operational environment. We analyze a dataset of adversarial fingerprinting behaviors, including protocol-level, behavioral, and environmental indicators used for honeypot identification. Based on observed attacker actions, we derive a taxonomy of effective SSH honeypot detection vectors. The results highlight practical weaknesses in deployed deception systems and provide actionable insights for improving the realism, robustness, and operational management of SSH honeypots. These findings support the design of more resilient deception infrastructures and contribute to measurement-based network security and threat intelligence practices
On quantum relations
No full textThis contribution proposes a conceptual framework for quantum relations understood as operator-based, scale-dependent semantic structures. It explores the “Fractaquantum” hypothesis, emphasizing that nature exhibits quantum properties at all scales, from subatomic particles to social structures. Using Pauli operators we propose a semantic theory of quantum relations based on the “semiotic square” and on Eigenlogic. The quantum two “one-half” spin composition defines the exchange operator at the basis of fundamental quantum relations. The approach is applied to macroscopic phenomena such as “Social Lasers” and the rhythmic “breathing” of entanglement, suggesting that individuality and social coherence are governed by scale-invariant quantum principles. This project aims to unify several quantum-like approaches under a common relational paradigm and highlights the role of fractal scaling, contextuality, non-commutativity, exchange, indistinguishability and entanglement in the emergence of semantic relations across physical, cognitive, social and artistic domains
Insights into the stability analysis of 2-by-2 linear weakly hyperbolic systems
No full textIn this paper, we address the exponential stability analysis of steady states for one-dimensional linear weakly hyperbolic systems of conservation laws and balance laws, characterized by non-diagonalizable coefficient matrices. We derive sufficient conditions to ensure exponential stability, conducting the analysis both in the Laplace domain for a system of conservation laws and in the time domain using Lyapunov-based techniques. Numerical examples are presented to demonstrate the effectiveness of the proposed methods
Proposition of an ontology supporting context modeling in operational scenario development
No full textInternational audienceAir Traffic Control systems are complex sociotechnical systems which do not comprise solely technical elements, but also have human and organizational dimensions. Recent approaches to Systems Engineering, and in particular Human Systems Integration, are placing increasing emphasis on incorporating these non-technical considerations into the design processes of complex sociotechnical systems. In particular, one crucial aspect in design is to understand the operational context of the system. There is a lack of tools and languages expressive enough to include contextual information into system models. This is especially true for the Air Traffic Control field, as the operational context of a control tower and the tower itself are deeply intertwined and interdependent. This paper is a step towards the achievement of better integration of context-related knowledge into system design processes. We conducted a case study analysis based on a literature review and feedback from civilian and military air traffic control practitioners, and we propose an ontology of the contextual elements that characterize the context of air traffic control operations
Experimental characterization of nanosecond discharges in methane
No full textInternational audienceNanosecond Repetitively Pulsed (NRP) discharges initiated in CH4 are experimentally characterized using optical and electrical diagnostics. Measurements of voltage and current in the circuit indicate that the energy deposition is decomposed into successive steps due to the propagation of the nanosecond pulse in the coaxial cable, and its reflections. The spatialtemporal evolution of the total emission suggests that the plasma is initially out of equilibrium and transitions to a thermal spark regime during subsequent reflected pulses, which is confirmed by measurements showing the evolution of the electron density obtained via Stark broadening of Hα. Finally, traces of N2 are injected into the mixture to determine the translational temperature from the N2 second positive system. The dataset provides a partial view of the discharge dynamics and is part of an ongoing effort to determine the dominant processes driving the thermokinetics of NRP discharges in CH4. The data are also employed in a companion paper to validate models describing these dynamics