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International audience; In this paper, we present and discuss simultaneous records of current and wideband electric field waveforms at 380 km distance from the strike point associated with an upward bipolar flash initiated from the Säntis Tower. The flash contains 23 negative strokes and one positive stroke. The height of the ionospheric reflection for the positive pulse was inferred to be about 94.9 km, a value which is significantly higher than for negative pulses of this same flash, which range from 73 to 81 km. It is also found that the ratio of the peak field to the current peak is about two times smaller for the positive pulse compared to negative pulses. This difference can be attributed to a lower return stroke speed for the positive stroke compared to that for negative strokes, and also to the fact that the enhancement of the electric field due to the presence of the tower and the mountain might be more significant for negative pulses, which are characterized by faster risetimes, than for the positive pulse. Keywords—Bipolar lightning flash, simultaneous current and field measurement, ionospheric reflection, field-to-current conversion factor

This paper proposes a new approach to modeling the radio frequency (RF) electromagnetic disturbances in broadband power line communication (PLC) networks using the multi-conductor transmission line (MTL) theory. The model includes a differential-mode (DM) current propagation model and a common-mode (CM) current propagation model. The frequency range of interest is from 1MHz to 30MHz. Practical measurements are carried out to compare with the simulation results as a form of verification of the accuracy of the proposed models. Published version

This paper presents the feasibility study of using porous metal for electromagnetic shielding purposes. Using the highly porous aluminum (close to 90% porosity) as the material under study, its shielding effectiveness (SE) was studied systematically. A preliminary measurement was carried out to evaluate the SE of porous aluminum sample. This was followed by a full-wave EM modeling of the porous aluminum shielded box. Finally, a shielded enclosure was assembled using porous aluminum panels and the overall SE of this enclosure was measured. With the conventional installation method, the enclosure has been found to provide at least 60 dB shielding effectiveness in the frequency range of 250 kHz to 1 GHz. Published version

A novel measurement method has been developed to characterize the common-mode (CM) and differential-mode (DM) impedances of power line EMI chokes under realistic loading conditions. With a proper pre-measurement calibration process, all parasitic effects in the measurement setup can be eliminated. The measurement allows designer to assess the EMI suppression performance of these chokes with reasonable accuracy under various loading conditions. With the measurement results, a proper choke with optimum EMI suppression performance could be selected for a specific loading condition. Published version

A novel measurement method is proposed to evaluate the performance of a ferrite core on a power cord under actual operating condition. The proposed method allows the common-mode impedance of a ferrite core under in-circuit condition to be measured so that it provides a more realistic assessment of the noise suppression capability of the ferrite core. With a pre-measurement characterization process, possible error due to parasitic effects of the measurement setup can be determined and eliminated. Hence, good accuracy is achieved for the proposed measurement method. Published version

In the past only critical clock circuits are running at high speed but this is no longer true in today high-speed digital design world. Most of the digital traces on board are running at speed in excess of 200 MHz and drivers output with rise time less than 1 ns. Due to constraints of board size and highly complex designs, trace bends and inter-layer transitions through vias are unavoidable. This paper carries out a comprehensive study on the impacts of bends and ground return vias optimisation on signal integrity performance using a full-wave electromagnetic simulator. (CST Microwave Studio). This study will provide high-speed digital designers an in-depth assessment of these effects in high-speed GHz applications so that some design guides to avoid these effects can be established. Published version

A comprehensive crosstalk analysis for different layout configurations has been carried out. Using a full-wave electromagnetic simulation tool, crosstalk reduction techniques based on trace-to-trace separation, guard traces, inter-layer ground plane are studied. With the comprehensive simulated results, useful design guidelines are established so that the designers can select the appropriate layout methodology to achieve the desired level of crosstalk isolation. Published version

Machine (deep) learning represents mainstream re- search and development direction. This success can be linked to the ever-increasing computational capabilities and vast amounts of available data, resulting in ever more sophisticated machine learning models. The design and training of such machine learning models are challenging and expensive tasks, which incentivize companies to protect and keep it secret. Additionally, the wide applicability of machine learning results in diverse deployment scenarios. Many machine learning architectures are deployed on edge devices, such as sensors or actuators, making them susceptible to side-channel attacks. This work surveys the research works considering electromagnetic side-channel and edge-based machine learning models. After discussing state-of-the-art attacks and countermeasures, we propose several open problems to be investigated in future research. National Research Foundation (NRF) Submitted/Accepted version This research is supported in parts by the National Research Foundation, Singapore, under its National Cybersecurity Research & Development Programme/Cyber-Hardware Forensic & Assurance Evaluation R&D Programme (Award: NRF2018NCR-NCR009-0001). This work received funding in the framework of the NWA Cybersecurity Call with project name PROACT with project number NWA.1215.18.014, which is (partly) financed by the Netherlands Organisation for Scientific Research (NWO). Additionally, this work was supported in part by the Netherlands Organization for Scientific Research NWO project DISTANT (CS.019).

ilustraciones, gráficas El siguiente trabajo desarrolla un modelo de pronóstico de demanda de energía a partir del empleo de datos aportados por medidores inteligentes. El algoritmo híbrido de optimización propuesto para el análisis fue implementando al integrar herramientas como series de Fourier, regresión simbólica y algoritmo multiobjetivo. Los resultados obtenidos son planteados sobre una base histórica de tres años. El estudio de pronóstico presentado se obtuvo a partir de un modelo estimador que acopla variables climáticas como presión, nubosidad, humedad, temperatura, dirección y velocidad del viento. Como también aspectos como el tipo de construcción, tipo de medidor, entre otros que contribuyen en un pronóstico a fin con el comportamiento base de demanda de energía de los usuarios analizados. Inicialmente se desarrolla el planteamiento del modelo de algoritmo híbrido empleado con el cual se realizarán los pronósticos de demanda de energía, realizando una descripción del funcionamiento de este. Posteriormente se realiza la implementación del algoritmo planteado en varios escenarios de tiempo, implementación que se desarrolla al disponer de datos históricos base de demanda de energía con los cuales se efectúan las pruebas del algoritmo, consecutivamente se evaluarán los resultados obtenidos sobre los datos de prueba de entrenamiento elegidos y prueba del código. (Texto tomado de la fuente) The following work develops an energy demand forecasting model based on the use of data provided by smart meters. The hybrid optimization algorithm proposed for the analysis was implemented by integrating tools such as Fourier series, symbolic regression and multiobjective algorithm. The results obtained are presented on a three-year historical basis. The forecast study presented was obtained from an estimator model that couples climatic variables such as pressure, cloud cover, humidity, temperature, direction, and wind speed. As well as aspects such as the type of construction, type of meter, among others that contribute to a forecast in order with the base behavior of the energy demand of the analyzed users. Initially, the approach to the hybrid algorithm model used is developed with which the energy demand forecasts will be made, making a description of its operation. Subsequently, the implementation of the algorithm proposed in various time scenarios is carried out, an implementation that is developed by having historical data base of energy demand with which the algorithm tests are carried out, the results obtained on the test data of chosen training and code testing. Maestría Magister en Ingeniería - Ingeniería de Eléctrica Medición de Energía, Pronóstico de Demanda, Optimización usando algoritmos heurísticos, Smart Grids

International audience; Electromagnetic interference (EMI) represents one of the biggest problems facing the production of any electronic device. The impact on the performance of the device caused such unwanted interference must be carefully measured to understand and quantify the electromagnetic compatibility (EMC) of the instrument under test. The electrical power conversions are among the sources of electromagnetic pollution, they provide a low power factor and generate electromagnetic interference (EMI). The white light emitting diode (LED) has attracted a lot of attention from industry and scientific researchers due to its high efficiency, easy of driving, and long life. Nevertheless, LED driver can interfere with the electronic device system due to rapid voltage variation and current. In this paper we simulate some LED driver topology on LTspice software in order to measure the electromagnetic disturbances using LISN (line impedance stabilizer network) device.

Corresponding authors: Zihao Wang; Chulsoon Hwang.; International audience; This paper proposes a jitter aware decoupling placement optimization method for capacitors that uses the genetic algorithm (GA). In addition, a novel method for defining the optimization target function in regard to power delivery network (PDN) optimization based on the GA-based tool is proposed. The proposed method can provide an optimum and economic solution for the number of decoupling capacitors to use in a power delivery network (PDN). In addition, by modifying the optimization target function with our proposed method, an optimum solution regarding both the number of decoupling capacitors and the power source induced jitter (PSIJ) can be obtained. The PSIJ analytical expressions are derived in conjunction with a resonant cavity model that includes the coordinates of the decoupling capacitors and the PSIJ transfer function. The GAbased optimization algorithm with the proposed target function is first applied to optimize the number of decoupling capacitors, and then, the PSIJ is taken into account. A comparison between these two cases is made, with the results proving the efficiency of our proposed method. Finally, the measured jitter from HSPICE simulation results is used to verify our optimization method, such that both the simulated results and analytically calculated results support the efficiency of our proposed optimization method.

A simple control strategy of the three-phase shunt active power filter that is connected to a non-linear load network is proposed. The filter consists of a three-phase voltage source inverter based on fully controlled switches, capacitor storage, and a first-order three-phase RL filter. The decomposition of the object of study according to the rates of motion of the dynamic system was performed. The fast subsystem is a circuit of compensation current control, the slow subsystem performs stabilization of the capacitor voltage. The basis of this approach is the separation of the vector of state variables into groups of components and their consistent use as control actions. To stabilize the DC voltage on the storage capacitor, a double twisting algorithm, which is based on the forced introduction of a one-dimensional second order sliding mode is used. The proposed strategy provides asymptotic stability in the error metric of the second-order sliding mode . The output signal of the voltage stabilization subsystem is a component of the reference signal for the current tracking circuit. A low pass filter to separate the subsystems is used. Compensation current is forming by the forced entering the first-order sliding mode. To reduce the number of current sensors in the system, an indirect control strategy is used. To generate the compensation current, a two-dimensional sliding manifold, which is a linear combination of components of two-dimensional vectors - the current error of the RL filter and some variable is used. The form of this variable is determined on the assumption that the first-order sliding mode in the current loop already exists and is ideal. Each component of this sliding surface is a linear combination of components of two-dimensional vectors. The first vector is the current error of the RL filter, the coordinates of the second are locally equivalent to the derivative of fundamental harmonic of this error. A simulation model is built and the simulation results are analyzed. The proposed strategy is compared with the traditional PI-regulation on the criteria of the duration of the transient process and the coefficient of harmonic distortion in the current consumed from the grid., Пропонується проста стратегія керування трифазним паралельним активним фільтром, який приєднано до мережі, з урахуванням наявності нелінійного навантаження. Фільтр складається з напівпровідникового інвертора напруги на повністю керованих ключах, ємнісного накопичувача та одноланкового RL-фільтра. Проведено декомпозицію об’єкта дослідження за темпами рухів динамічної системи. Для стабілізації постійної напруги на накопичувальному конденсаторі використано алгоритм подвійного скручування, який базується на примусовому введенні одновимірного ковзного режиму другого порядку. Слідкування за компенсаційним струмом відбувається за допомогою введення ковзного режиму першого порядку і застосовується стратегія непрямого керування. Для формування струму використовується двовимірна поверхня ковзання, яка є лінійною комбінацією компонентів двовимірних векторів - похибки струму RL-фільтра та деякої змінної. Побудовано імітаційну модель та проаналізовано результати моделювання. Проведено порівняння запропонованої стратегії з традиційним ПІ-регулюваням за критеріями тривалості перехідного процесу та коефіцієнтом гармонічних спотворень у струмі, який споживається з мережі.

International audience; AC railways are characterized by peculiar Power Quality phenomena, where moving loads (trains, locomotives, etc.) inter- act with the supply network that provides electrical energy through the overhead contact line. Distortion, resonances, transients overlap in a complex dynamic scenario, that sees several and various problems of Power Quality, network stability, power and energy metering and disturbance to systems and equipment. For all related studies and analysis raw experimental data are extremely important. The provided data consists of time-domain waveforms of sampled panto- graph voltage and current: each recording is tagged with the specific train operating condition (traction, cruising/coasting, braking, standstill), the active power and the speed, to sup- port correlation and clustering of data.

International audience; Numerical solution methods for electromagnetic scattering problems lead to large systems of equations with millions or even billions of unknown variables. The coefficient matrices are dense, leading to large computational costs and storage requirements if direct methods are used. A commonly used technique is to instead form a hierarchical representation for the parts of the matrix that corresponds to far-field interactions. The overall computational cost and storage requirements can then be reduced to O(N log N). This still corresponds to a large-scale simulation that requires parallel implementation. The hierarchical algorithms are rather complex, both regarding data dependencies and communication patterns, making parallelization non-trivial. In this chapter, we describe two classes of algorithms in some detail, we provide a survey of existing solutions, we show results for a proof-of-concept implementation, and we provide various perspectives on different aspects of the problem. The list of authors is organized into three subgroups, Larsson and Zafari (coordination and proof-of-concept implementation), Righero, Francavilla, Giordanengo, Vipiana, and Vecchi (definition of and expertise relating to the application), Kessler, Ancourt, and Grelck (perspectives and parallel expertise).

Several recent contributions have envisioned the possibility of increasing currently exploitable maximum channel capacity of a free space link, both at optical and radio frequencies, by using vortex waves, i.e. carrying Orbital Angular Momentum (OAM). Our objective is to disprove these claims by showing that they are in contradiction with very fundamental properties of Maxwellian fields. We demonstrate that the Degrees of Freedom (DoF) of the field cannot be increased by the helical phase structure of electromagnetic vortex waves beyond what can be done without invoking this property. We also show that the often-advocated over-quadratic power decay of OAM beams with distance does not play any fundamental role in the determination of the channel DoF., Comment: 8 pages, 7 figures

International audience; Lightning is highly destructive due to its high power density and unpredictable character. Directing lightning away would allow to protect sensitive sites from its direct and indirect impacts (electromagnetic perturbations). Up to now, lasers have been unable to guide lightning efficiently since they were not offering simultaneously terawatt peak powers and kHz repetition rates. In the framework of the Laser Lightning Rod project, we develop a laser system for lightning control, with J-range pulses of 1ps duration at 1kHz. The project aims at investigating its propagation in the multiple filamentation regime and its ability to control high-voltage discharges. In particular, a field campaign at the S ̈antis mountain will assess the laser ability to trigger upward lightning.

International audience; The authors present an analysis of different charge transfer modes during upward negative flashes. The analysis includes a total number of 94 pulses that occurred during two upward negative flashes recorded at the Säntis Tower. The pulses included 59 mixed-mode (MM) initial continuous current (ICC) pulses, 17 M-component-type ICC (M-ICC) pulses, 8 returnstroke pulses, and 10 classical M-component (MC) pulses. It is found that the initial stage of the flash is responsible for the largest share of the total charge transferred to the ground. Simulation results for the electric fields associated with the considered charge transfer modes are presented and discussed. Return stroke (RS) and MM pulses were simulated adopting the MTLE model, while MCs and M-ICC pulses were simulated using the guided wave model of Rakov et al. The simulated results are shown to be in good agreement with simultaneous records of electric fields measured at a distance of 15 km from the Säntis Tower. The inferred velocities for MCs and M-ICC pulses range from 2.0 × 10 7 to 9.0 × 10 7 m/s, and the corresponding junction point heights range from 1.0 to 2.0 km. The inferred pulse velocities for RSs and MM pulses range from 1.3 × 10 8 to 1.65 × 10 8 m/s. The inferred current attenuation constants of the MTLE model obtained in this study range from 0.3 to 0.8 km, lower than the value of 2 km previously suggested for RSs in downward flashes. The obtained results support the assumption that the mode of charge transfer to the ground giving rise to MM pulses is similar to that of RSs. The results are also in support of the generally assumed similarity between M-ICC pulses and classical MCs.

An unusual negative lightning flash was recorded at the Santis Tower on June 15, 2012. The flash did not contain an initial continuous current typical of upward negative lightning, which is the most common type of event at the Santis Tower. The flash contained four strokes, the last three of which were normal while the current associated with the first stroke resembled a Gaussian pulse with an unusually high peak value of 102.3 kA, a long risetime of 28.4 μs, and a pulsewidth of 53.8 μs, which was followed by an opposite polarity overshoot with a peak value of 8.5 kA. Our current records suggest the involvement of a long upward connecting positive leader in response to the approaching downward negative leader in the formation of this flash. Lightning location system (LLS) data indicate that a positive cloud-to-ground stroke occurred 1 ms prior to the first stroke of the flash. In this paper, we present a detailed description of the data associated with this event. Moreover, both a return stroke model and an M-component model are used to reproduce the far-field waveform of this bipolar stroke. The simulations result in a radiated electric field waveform that is similar to those of large bipolar events (LBEs) observed in winter thunderstorms in Japan. A sensitivity analysis of the used simulation models reveals that, by proper selection of the input parameters, all field waveform characteristics, except for the positive half-cycle width, can be made to fall in the range of LBE field characteristics reported in Japan.

co-auteur étranger; International audience; Zircon U-Pb geochronology is a very robust dating method but the accuracy of determinedages can sometimes be compromised. This is because, as commonly observed, the U-Pb isotope system canbe reopened during the post-crystallization evolution of a zircon. The present manuscript investigates thecapability of traverses by LA-ICP-MS to identify zones of well-preserved U-Pb isotope systematics within zir-con crystals. The data for the different zones can be used to construct internal Discordia lines that provideage information about crystallization and metamorphism of single zircon crystals. To test our approach, weanalyzed zircons from three ca. 3.96 Ga Acasta gneisses. Results demonstrate that such a method allowsretrieval of original crystallization age in most of the studied zircons, even in those that experienced ancientU-Pb disturbances resulting in discordant U-Pb data. It was also possible to estimate disturbance ages,though not as precisely as for the igneous crystallization, in many of the studied crystal

El estudio desarrolla un análisis de la compatibilidad electromagnética en los recintos hospitalarios. En el mismo se trata de establecer las características del diseño inicial de la red eléctrica que permiten obtener un contexto electromagnético óptimo en el funcionamiento de los sistemas hospitalarios. En el trabajo se aborda el análisis de los distintos regímenes de neutro de las instalaciones de baja tension, con el objeto de establecer un estándar justificado que facilite la operación y funcionamiento de la instalación eléctrica y de comunicaciones en los sistemas hospitalarios. El análisis de los datos recabados permite proponer la utilización del régimen de neutro TN-S. Finalmente, se plantea para un futuro desarrollo normativo y de diseño la utilización del régimen de neutro TN-S como medida correctora para mejorar el funcionamiento electromagnético de centros hospitalarios. ----------ABSTRACT---------- This research analyzes the electromagnetic compatibility in hospital buildings and tries to stablish the initial design features of its low voltage systems for the better electromagnetic context. The present study analyzes different neutral regimes in low voltage networks and proposes a justified standard for electrical and communication networks which allows an optimal running in hospital systems. Based on the data and outcomings it is proposed a TN-S grounding system. It is proposed, for a future regulation development, the use of the TN-S grounding system for a better electromagnetic operation in hospital buildings.