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Combining SysML V2 and BIP to Model and Verify CPS Interactions
No full textInternational audience<font face="arial, helvetica"><span style="font-size: 13px;"> Cyber-physical systems (CPS) require precise interaction modeling and rigorous verification to guarantee reliability and correctness, particularly in safety-critical systems, where interaction errors such as deadlocks may lead to critical failures. Although SysML v2 provides expressive modeling capabilities, it lacks explicit execution semantics for structured interactions. To address this limitation, we propose a structured subset of SysML v2 to specify interactions at the structural level. These interactions are then mapped to the Behavior, Interaction, Priority (BIP) framework, which defines their execution semantics and enables formal analysis. Specifically, we introduce Rendez-vous and Broadcast connectors to enforce synchronization and one-to-many communication, respectively, ensuring that interactions are explicitly represented and amenable to formal analysis. BIP provides precise execution semantics, facilitating rigorous verification and streamlining the process by eliminati ng the need for external verification models. We validate our approach through a case study on swarm drone coordination, demonstrating structured execution, the ability to detect and resolve critical deadlocks, and the correctness and robustness of interactions.</span></font&g
Opto-mechanical chiral microrobot for out-of-plane rotation
No full textInternational audience<font face="arial, helvetica"><span style="font-size: 13px;">Optical tweezers use tightly focused laser beams to trap and manipulate microscopic particles by balancing scattering forces with a gradient force at the beam’s focal point. This enables precise and contact-free particle control, making optical tweezers a powerful tool to activate microrobots (optobots) that give multiple degrees of freedom. However, realizing out-of-plane rotation, which is demanded for medical applications such as cellmanipulation and drilling, remains a challenge. Here, we present an optobot design leveraging chirality to achieve full-cycle out-of-plane rotation. This optobot has an elongated structure with dual optical handles and a chiral helix aligned on the long axis of the robot. The optical handles are used to be trapped by the optical tweezers beams to keep the long axis of the optobot and the helix perpendicular to the laser light propagation, while its chiral helical part generates out-of-plane rotation around its long axis under laser excitation due to broken axial parity. Finite element analysis was conducted to simulate the interaction of the chiral helix with the laser beam. The scattered beam distribution was visualized to see how it is altered by the chiral structure. The optical torque was also calculated to show that it is unidirectional following chirality. For experimental demonstration, the optobot was fabricated via two-photon lithography. The optical manipulation experiments using an optical tweezer system showed that the optobot demonstrates versatile actuation capabilities, achieving on-demand repetitive rotation, controlled-speed translation, and combined rotational-translational motion.</span></font&g
Observer-based sliding mode boundary control of uncertain Markovian stochastic reaction–diffusion system
No full textInternational audienceThis paper deals with the robust mean square exponential stabilization for uncertain Markovian stochastic reaction–diffusion systems (UMSRDS) via the observer-based sliding mode boundary control (SMBC). First, a suitable boundary-output-based observer is constructed for estimating the unknown system states. Next, to process the impact of Markovian switching, a mode-dependent integral sliding mode surface (SMS) is established, on which the closed-loop system is mean square robust exponentially stable. Furthermore, an observer-based sliding mode boundary controller (SMBCr) is designed to guarantee the almost sure reachability of the predefined SMS. Then, a mode-dependent condition is provided to ensure the robust mean square exponential stability of the closed-loop system. Finally, the proposed method is applied to a CPU thermal model to illustrate the effectiveness of theoretical results
Catalyst degradation in proton exchange membrane fuel cells: Mechanisms, investigation techniques, and predictive modelling
No full textInternational audienceProton Exchange Membrane Fuel Cells (PEMFCs) represent a promising solution for sustainable energy. However, the degradation of their catalyst layer (CL), particularly platinum-based catalysts, remains a major barrier to their efficiency and long-term durability. This review summarizes the key degradation mechanisms within the CL, including platinum dissolution, Ostwald ripening, carbon support corrosion, and nanoparticle agglomeration. It further examines experimental and characterization techniques employed to investigate these mechanisms. Specifically, it discusses accelerated stress tests (ASTs) and life tests used to mimic long-term performance loss under realistic conditions, alongside electrochemical and microscopic methods for monitoring structural and chemical transformations. In addition, it highlights predictive modelling approaches, both model-based and data-driven, that offer effective strategies to forecast degradation trends and guide catalyst design. Finally, this work proposes the use of hybrid modelling, integrating both physics-based and data-driven approaches, as a holistic framework to improve the understanding and mitigation of CL degradation, ultimately contributing to the development of more durable and efficient PEMFC systems
Distributed formation control for port-Hamiltonian multi-agent systems by average state estimation
No full textInternational audienceIn recent years, propelled by the rapid development of informationtechnology and the Internet, the formation control of multi-agentsystems has gradually emerged as a research hotspot. This paperfocuses on the formation control problem of multi-agent mechanicalsystems with port-Hamiltonian (PH) dynamics. Firstly, the formationproblem is converted into an optimization problem whose solutionmeets the formation requirements. Subsequently, in order to guidethe closed-loop system to converge to the solution of thisoptimization problem, we propose two distributed controllers. Thefirst controller is designed for multi-agent systems where theformation output is defined by position. Notably, this controllerpreserves the PH structure in the closed-loop, which simplifies theselection of candidate Lyapunov functions for proving theasymptotic convergence of the system to the desired formation. Tocharacterize the minimum convergence rate of the closed-loopsystem, the second controller is proposed. Based on thiscontroller, the exponential stability and the minimum convergencerate of the closed-loop system are provided. Additionally, thesecontrollers only require agents to exchange estimations of theaverage state with their neighbors, thereby protecting the privacyof their state and value function information. Finally, theeffectiveness of these controllers is verified through anapplication case on nonholonomic wheeled robot
Distributed Control Strategy for Rotor Speed Synchronization in Multiple PMSMs Based on Port-Hamiltonian Dynamics
No full textInternational audienceIn this paper, the synchronous rotor speed control problem ofmultiple permanent magnet synchronous motors (PMSMs) withport-Hamiltonian (PH) dynamics is considered. Firstly, we convertthe synchronous rotor speed problem to an optimization problem, andbased on this, a distributed controller is proposed for each PMSMusing the information exchange between PMSMs. However, theexchanged information is the average rotor speed estimation valueof each PMSM rather than the direct rotor speed, which mayfacilitate the sensitive state protection. Then, the stability ofthe closed-loop system is analyzed and we prove that theequilibrium of the closed-loop system is consistent with theoptimum of the value function of the optimization problem. Finally,a simulation example is provided to validate the effectiveness ofthe proposed distributed controller
Human contributions to global soundscapes are less predictable than the acoustic rhythms of wildlife
No full textInternational audienceAcross the world, human (anthropophonic) sounds add to sounds of biological (biophonic) and geophysical (geophonic) origin, with human contributions including both speech and technophony (sounds of technological devices). To characterize society’s contribution to the global soundscapes, we used passive acoustic recorders at 139 sites across 6 continents, sampling both urban green spaces and nearby pristine sites continuously for 3 years in a paired design. Recordings were characterized by bird species richness and by 14 complementary acoustic indices. By relating each index to seasonal, diurnal, climatic and anthropogenic factors, we show here that latitude, time of day and day of year each predict a substantial proportion of variation in key metrics of biophony—whereas anthropophony (speech and traffic) show less predictable patterns. Compared to pristine sites, the soundscape of urban green spaces is more dominated by technophony and less diverse in terms of acoustic energy across frequencies and time steps, with less instances of quiet. We conclude that the global soundscape is formed from a highly predictable rhythm in biophony, with added noise from geophony and anthropophony. At urban sites, animals experience an increasingly noisy background of sound, which poses challenges to efficient communication
Work passion, work–family conflict, and counterproductive work behaviors
No full textInternational audienceWe examined whether obsessive passion and harmonious passion interacted in the prediction of work–family conflict, and the indirect effects of obsessive passion on counterproductive work behaviors as mediated by work–family conflict. We collected data from two samples of employees with jobs in engineering (Sample 1) and administration (Sample 2). Obsessive passion was associated with higher levels of work–family conflict, whereas harmonious passion was negatively related to work–family conflict. Furthermore, the positive effects of obsessive passion on work–family conflict were lower at high levels of harmonious passion. Work–family conflict was also positively related to counterproductive work behaviors (Sample 2). Finally, the indirect effects of obsessive passion on counterproductive work behaviors (Sample 2) were lower at high levels of harmonious passion
Effet du type d'assistance d'une interface modulaire robotisée sur le sens d'agentivité
No full textInternational audienceRobotic modular interfaces, increasingly studied in Human-Computer Interaction, offer assistance to support users in their tasks. However, this assistance can harm the sense of agency (i.e., feeling of control), leading to non-use of the interface or a diminishing sense of responsibility regarding the consequences of users' actions. The impact of robotic modular interface assistance, during a cooperative task, on the user's sense of agency has not yet been studied. In this article, we propose to remedy this through the use of swarm robotic interfaces. We focus on nine levels of assistance, varying system autonomy and module coordination. Our study shows that: (1) the higher the autonomy, the lower the sense of agency, (2) coordination seems to have an impact on the sense of agency, and (3) three types of sense of agency emerge depending on the coordination of the modules.Les interfaces modulaires robotisées, de plus en plus étudiées en Interaction Humain-Machine, proposent de l’assistance pour soutenir les utilisatrices dans leurs tâches. Cependant, cette assistance peut nuire au sens d’agentivité (c.-à-d. sentiment de contrôle), amenant à la non-utilisation de l’interface ou à la déresponsabilisation de l’utilisatrice face aux conséquences de ses actes. L’impact de l’assistance des interfaces modulaires robotisées, lors d’une tâche de coopération, sur le sens d’agentivité de l’utilisatrice n’a pas encore été étudiée. Dans cet article, nous proposons d’y remédier via l’utilisation d’interfaces modulaires en essaim. Nous nous intéressons à neuf niveaux d’assistance, variant autonomie du système et coordination des modules. Notre étude montre que : (1) plus l’autonomie est élevée plus le sens d’agentivité sera faible, (2) la coordination semble avoir un impact sur le sens d’agentivité et, (3) trois types de sens d’agentivité émergent en fonction de la coordination des modules