École Supérieure d'Électronique de l'Ouest

This paper presents a compact, vertically-polarized, ultra-wideband monocone antenna with low volume (24×24×15 mm3) and weight (8 g) suitable for wearable applications. It features a 96.1% smaller ground plane and a 75.2% lower volume than the smallest-height UWB reference design, while maintaining comparable performance. Its structure comprises a metal cone radiator and a modified circular top-plate shorted with four thin rods to a ground plane as small as the size of a standard four-hole flange-mount SMA connector. Detailed design guidelines are provided, including analyses of current distribution, parametric study, and equivalent circuit models. Both frequency- and time-domain results are measured to validate the design. The measured (simulated) antenna -10 dB bandwidth ranges from 3.1 (2.85) to 10.4 (10.3) GHz, exhibiting a fractional bandwidth of 108.1% (113.3%). The proposed antenna is highly efficient (over 95%) and consistently exhibits stable omni- and bi-directional radiation patterns in the two principal planes, with a stable measured and simulated average realized gain of approximately 1.35 dBi in the ϕ = 0° and θ = 90° radiation direction over the 2.9-7.5 GHz frequency range. As far as the time-domain behavior is concerned, the system fidelity factor is found adequate (higher than 0.85) for the transmission of impulse-type UWB signals in free-space independently of orientation in the azimuthal plane. Additionally, two different on-body exposure scenarios are considered, one with the Tx and Rx antennas positioned over a human forearm and the other near the human ears, to demonstrate the suitability of the proposed design for on-body communication links.

In this paper, we address both a combinatorial continuation question via Lyapunov graphs and the attainability of a preassigned level set, dubbed ground level set and given by its Betti numbers, within a morsification process of a dynamical configuration. The novelty introduced here is a componentwise Lyapunov graph morsification that keeps track of level sets during the morsification process subject to the minimality of the total number of singularities of a morsified flow. The algorithm behind the morsification translates into a system of linear equations whose feasibility is linked to that of a set of inequalities, called componentwise Poincaré-Hopf inequalities, involving the input data. This investigation combines techniques from both homological Conley index and network flow theories.

This chapter introduces a hardware implementation on the field programmable gate arrays (FPGA) Zed-Board of the power management algorithm for wind turbine associated with a batteries module is considered as an energy storage device and a variable load. This power management system (PMS) optimizes system operation and addresses power disturbances resulting from wind speed intermittency and load changes. First, the proposed PMS ensures a balance at the continuous direct current bus, maintaining equilibrium between the power supplied by the wind turbine and the power demanded by the load. Furthermore, it prevents the batteries from surpassing their maximum or minimum state of charge, maintaining it within an acceptable range of 30%-90%. This proposed methodology effectively manages power flows within a wind energy conversion system (WECS), ensuring stable power delivery to the load while extending the longevity of the battery energy storage system (BESS) device. Second, the real-time implementation on the FPGA Zed-Board of the suggested PMS with BESS for WECS, aimed at reducing control loop delays and processing multiple signals in parallel, offers substantial advantages over conventional DSP-based systems. This positions it as a promising technology for future renewable energy systems. The system's performance is assessed through digital simulation in MATLAB®/Simulink® using the Xilinx system generator and real-time implementation utilizing an FPGA Zed-Board device. The results underscore the performance of the proposed approach in optimizing the WECS's performance.

In this paper, we investigate the application of machine learning techniques as a productive solution for carrying out LoRaWAN packet collision detection. Our focus is on a common channel that is shared by several LoRa end-devices via the asynchronous ALOHA protocol, with the aim of delivering data packets in IoT scenarios. We evaluate the effectiveness of two algorithms in this setup: Random Forest and Decision Tree. Higher efficiency is exhibited for identification and likelihood of False Positive Rate, even when packets transmissions collide.

This study presents the design of a bandpass filter based on a bandstop filter configuration, utilizing transverse filtering techniques. Subsequently, the integration of SRR (Split Ring Resonator) cells into the filter structure is explored to investigate their direct impact on its performance. Initially, a single SRR cell is tested, and then a second cell is added to illustrate their combined effect on the filter structure. The experimental results highlight the influence of SRR cell integration on the overall performance of the bandpass filter, providing insights into the significant role of these cells in shaping the filter's characteristics. The simulation is carried out using Advanced Design System (ADS) and CST Studio software, with the chosen substrate material being ROGERS RT/Duroid 6002, known for its specific properties including a 0.252 mm thickness, a dielectric constant of 2.94, and a loss tangent of 0.0012.

The phrase “Multi-Power System (MPS)” refers to an application that combines different energy conversion technologies to meet a specific energy need. These integrated power systems are rapidly being lauded as essential for future decarbonized grids to achieve optimum efficiency and cost reduction. The fact that MPSs multiply several sources also multiplies their advantages to be environmentally friendly and increases the possibility of energy autonomy as they do not depend on a single source. Consequently, this increases the reliability and reduces the production costs and the size of the storage system. However, the main disadvantages of such a system are the complexity of its architecture and the difficulty in managing the power level, which leads the system to face many faults and sometimes failure. In this case, a fault-tolerant control (FTC) system can automatically adapt to component malfunctions while maintaining closed-loop system stability to achieve acceptable performance. However, on the way to build efficient FTC, one first needs to study the faults that may occur in the system in order to tolerate them. This review paper presents the faults of the MPS electrical sources used in a hybrid system, including a photovoltaic generator and a diesel generator, plus a lead–acid battery as a storage device. Only the most-encountered faults are treated.

The unique set of LoRaWAN design prerequisites, which include low power consumption, costeffectiveness, and high scalability, requires its security protocols to be equally robust and enduring, especially since devices are often deployed for extended durations in the field. This research paper elucidates a novel cryptographic method for LoRaWAN, hinged on the Advanced Encryption Standard (AES) employing a 256-bit key. The efficacy and efficiency of the proposed cryptographic solution are analyzed through a comprehensive performance evaluation. Key performance indicators include the security metric, network throughput, and energy utilization of end-devices. It was observed that augmenting the key size from 128 to 256 bits notably bolsters the resilience of LoRaWAN against various cyber attacks. The results also indicate a marginal disparity between the proposed AES256-based method and the existing AES128-based method with regards to network throughput and energy consumption. However, the enhanced security provided by the AES256 standard underscores its potential as a viable cryptographic method for LoRaWAN, providing a favorable balance between improved security and operational performance.

The advent of autonomous vehicles has brought about significant advancements in transportation technology, promising safer and more efficient means of travel. However, their full integration into society depends on the accuracy of path-tracking realised by a lateral controller. Lateral control is achieved by regulating the steering angle to minimise the lateral error between the vehicle and a target point at a look-ahead distance on the reference path. This paper investigates the look-ahead distance as it is considered a key parameter that impacts vehicle performance, stability, and energy consumption. A qualitative analysis is performed to deduct a set of rules to adapt the look-ahead distance to three parameters: vehicle velocity, road curvature, and road adherence. Then, an original explicit mathematical formulation is developed for the look-ahead distance as a function of the considered parameters. A fuzzy logic decision for the look-ahead distance is further established and compared with the formulated one. Both approaches are implemented on a look-ahead distance-based lateral controller based on the super-twisting sliding mode control. Simulation results carried out in a joint simulation between Simulink/MatLab and SCANeR TM Studio vehicle dynamics simulator demonstrate the effectiveness of the developed model on vehicle performance, stability, computational efficiency, and energy consumption.

This research paper presents a methodology for optimizing the placement of an electric single source in a DC islanded microgrid mesh network with the aim of minimizing line losses while considering minimal cables weight. The paper utilizes the Dijkstra algorithm (a graph algorithm used in Google Maps) to identify the shortest path between a potential source node and all other variable loads in a predefined electric distribution mesh network topology. The resulting optimal placement of sources is ordered based on their corresponding line losses and optimal cables weight. Connected nodes in the mesh network are predefined, but lines optimal resistances are computed by the algorithm. The study only considers active power and provides insights into optimizing the placement of sources in DC microgrid mesh networks. The main contribution of this paper is to rank source node positions from least to highest line losses. The paper also provides a comparison of the mesh networks based on the optimal cables weight used when placing a source at a defined position. The proposed methodology can be useful for system designers and operators seeking to minimize line losses and optimize energy distribution in DC microgrids using a mesh network topology.