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The Equatorial Ionization Anomaly (EIA), a manifestation of Ionospheric plasma irregularities, is closely linked to the equatorial fountain, influenced by solar activity and Earth's geomagnetic field. While previous studies on EIA have predominantly focused on specific regional analyses using TEC data from GPS stations, revealing correlations between peaks, discrepancies with models, and temporal variations, there exists a gap in comprehensive global statistics, consideration of different solar activity years, and exploration of EIA characteristics across various local time scales. To address these, this study employs high spatiotemporal data from the Global Ionospheric Map (GIM) to comprehensively analyze EIA across different periods of the day during high solar activity in 2014 and low solar activity in 2020. The study delves into the subtle variations of EIA under different solar activity levels and seasonal conditions, focusing on changes in occurrence rate, intensity, and geomagnetic latitude positions concerning longitude, month, and local time. Our study reveals several findings: (1) EIA exhibited more frequent and intense trends during high solar activity years, with higher occurrence rates and intensity observed during the equinoxes; (2) EIA exhibits significant variations across different longitudes and local times, showing systematic patterns in its occurrence rates over time; (3) The crest-to-trough TEC Ratio (CTR) effectively characterizes nighttime EIA intensity, while the crest-to-trough TEC Difference (CTD) is suitable for representing daytime EIA intensity; (4) The temporal changes in EIA positions may be related to electric fields and wind patterns, while differences in longitudes are attributed to variations in the geomagnetic field. [ABSTRACT FROM AUTHOR]

The fractional-slot, concentrated-winding, interior permanent magnet synchronous motor (FSCW IPMSM) has advantages, such as reducing motor copper consumption, improving flux-weakening capability, and motor fault tolerance, and has certain development potential in application fields such as electric vehicles. However, fractional-slot concentrated-winding motors often contain rich harmonic components due to their winding characteristics, leading to increased motor losses and back electromotive force harmonics, thereby affecting the efficiency and constant power speed regulation range of the motor. Based on this, this article first uses the winding function method to explore the inductance and saliency ratio of the interior permanent magnet synchronous motor with different slot pole combinations in the fractional-slot concentrated- winding of electric vehicles. Secondly, this article will establish a 2D finite element parameterized model to analyze and compare the performance of fractional-slot concentrated-winding motors with different slot pole combinations, including air gap magnetic density, back electromotive force distortion rate, overload multiple, and torque. The structural parameters of the motor were optimized with the objective of minimizing the torque ripple under the constraint of minimizing the average torque reduction. The motor slot width, permanent magnet angle, and permanent magnet pole arc angle were analyzed and optimized. The simulation results showed that 12 slots and 8 poles were the optimal design schemes, providing a theoretical basis for the selection of slot pole coordination in the fractional-slot concentrated-winding interior permanent magnet synchronous motor for electric vehicles. [ABSTRACT FROM AUTHOR]

Power quality improvements help guide and solve the problems of inefficient energy production and unstable power output in wind power systems. The purpose of this paper is mainly to explore the influence of different energy storage batteries on various power quality indicators by adding different energy storage devices to the simulated wind power system, and to explore the correlation between system entropy generation and various indicators, so as to provide a theoretical basis for directly improving power quality by reducing loss. A steady-state experiment was performed by replacing the wind wheel with an electric motor, and the output power qualities of the wind power system with and without energy storage were compared and analyzed. Moreover, the improvement effect of different energy storage devices on various indicators was obtained. Then, based on the entropy theory, the loss of the internal components of the wind power system generator is simulated and explored by Ansys software. Through the analysis of power quality evaluation indicators, such as current harmonic distortion rate, frequency deviation rate, and voltage fluctuation, the correlation between entropy production and each evaluation indicator was explored to investigate effective methods to improve power quality by reducing entropy production. The results showed that the current harmonic distortion rate, voltage fluctuation, voltage deviation, and system entropy production are positively correlated in the tests and that the power factor is negatively correlated with system entropy production. In the frequency range, the frequency deviation was not significantly correlated with the system entropy production. [ABSTRACT FROM AUTHOR]

The paper presents the results of research on the spatial distribution of the multi-phase, distributed windings in electric machines. The focus was on the analysis of the harmonics of the current linkage spatial distributions. To perform calculations for different windings patterns, taking into account the number of phases, pole pairs, and the number q of slots per pole and phase, the dedicated code was developed in the Matlab environment. Nine different multi-phase windings were studied, for which magnetomotive force (MMF) was determined to investigate the harmonic content and total harmonic distortion. The obtained results were compared with a reference three-phase symmetric system. Studies were also carried out on torque ripple and power density for different numbers of winding phases. [ABSTRACT FROM AUTHOR]

With the increasing number of distributed power sources such as photovoltaic power and wind power and electric vehicles connected to the grid, the structure and operation state of the traditional distribution network have undergone great changes. Therefore, through the establishment of a distributed power grid-connected evaluation system, it has become an important research topic to evaluate the access of distributed power and the carrying capacity of electric vehicles in the distribution network of new power systems. Firstly, the situation of distributed power supply and electric vehicles and the impact of grid connection are introduced. Secondly, the traditional distribution network carrying capacity evaluation method is studied and introduced. Then, the distribution network carrying capacity evaluation considering uncertainty is reviewed and investigated. Finally, in view of the lack of existing research, further research is needed, aiming to provide a reference for the realization of distributed power supply and grid-connected EV carrying capacity evaluation and a scientific basis for the future operation planning of distributed power supply and EV integration into the distribution network. [ABSTRACT FROM AUTHOR]

The Martian bow shock has been extensively studied through magnetic field and plasma instrument observations from various Mars space missions. However, prior investigations primarily involve statistical analyses based on single spacecraft crossings, leaving the asymmetry of the Martian bow shock unstudied through simultaneous two‐spacecraft observations. In this study, utilizing simultaneous observations from Tianwen‐1 and MAVEN, we examine the instantaneous asymmetry of the Martian bow shock. We present the asymmetry of the Martian bow shock in the Mars‐Solar‐Electric and Mars‐Solar‐Orbital reference frames, possibly influenced by the solar wind motional electric field and Martian crustal magnetic field, respectively. Moreover, we suggest that the bow shock exhibits increased asymmetry under stronger solar wind motional electric field conditions. This study highlights how a two‐point observation approach offers valuable insights into the dynamic behavior of the Martian induced magnetosphere. Plain Language Summary: Scientists have been studying the Martian bow shock, which slows down the solar wind from supersonic to subsonic, using instruments on different Mars missions. But most studies only use data from one spacecraft, so we don't know much about how the bow shock varies in different places at the same time. In this study, we looked at data from two spacecraft, Tianwen‐1 and MAVEN, at the same time to see if we could find any differences. We found that the bow shock is different in the northern and southern parts of Mars in different reference frames, and this might be because of the solar wind electric field and the Martian crustal field. We also noticed that the bow shock is more different when the solar wind electric field is stronger. Such two‐spacecraft observations helps us understand more about how the magnetic environment around Mars works. Key Points: We investigated the asymmetry of Martian bow shock utilizing two‐spacecraft observations at distinct locationsThe dayside Martian crustal field may induce the north‐south asymmetry of the bow shockThe solar wind electric field may cause bow shock asymmetry in the Mars‐Solar‐Electric frame, with stronger fields increasing the effect [ABSTRACT FROM AUTHOR]

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Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Electric Solar Wind Sail (E-sail) deflects charged particles from the solar wind through an artificial electric field to generate thrust in interplanetary space. The structure of a spacecraft equipped with a typical E-sail essentially consists in a number of long conducting tethers deployed from a main central body, which contains the classical spacecraft subsystems. During flight, the reference plane that formally contains the conducting tethers, i.e., the sail nominal plane, is inclined with respect to the direction of propagation of the solar wind (approximately coinciding with the Sun–spacecraft direction in a preliminary trajectory analysis) in such a way as to vary both the direction and the module of the thrust vector provided by the propellantless propulsion system. The generation of a sail pitch angle different from zero (i.e., a non-zero angle between the Sun–spacecraft line and the direction perpendicular to the sail nominal plane) allows a transverse component of the thrust vector to be obtained. From the perspective of attitude control system design, a small value of the sail pitch angle could improve the effectiveness of the E-sail attitude maneuver at the expense, however, of a worsening of the orbital transfer performance. The aim of this paper is to investigate the effects of a constraint on the maximum value of the sail pitch angle, on the performance of a spacecraft equipped with an E-sail propulsion system in a typical interplanetary mission scenario. During flight, the E-sail propulsion system is considered to be always on so that the entire transfer can be considered a single propelled arc. A heliocentric orbit-to-orbit transfer without ephemeris constraints is analyzed, while the performance analysis is conducted in a parametric form as a function of both the maximum admissible sail pitch angle and the propulsion system's characteristic acceleration value. [ABSTRACT FROM AUTHOR]

Electric vehicles are recently prosperous due to decarbonization and electrification in transportation. However, manufacturing their motor windings with stable high quality is challenging, especially in hairpin laser welding. This study introduces a novel interpolator using polar angles as primary indicators, achieving process flexibility and high-performance synchronization between positions and powers. The interpolator is well-designed theoretically, more advantageous compared to those traditional ones in hairpin welding, while also compatible with them. Four speed planning modes are available depending on whether the speed is angular or linear, constant or variable. Additionally, energy distributions based on polar-angle power profiles can be adjusted and optimized according to practicality. Both the speed and power profiles, as two critical welding parameters, facilitate precise in-process modification dramatically. In the end, two groups of comparative experiments are performed to positively validate the interpolator's feasibility and effectivity to improve weld quality. Significantly, this work establishes a fundamental framework linking diverse paths and hairpin welding processes which is essential for weld quality control and optimization. [ABSTRACT FROM AUTHOR]

This article presents a detailed analysis of the electromagnetic force and vibration behavior of a new axial flux permanent magnet (AFPM) machine with a yokeless stator and interior PM rotor. Firstly, the configuration of an AFPM machine with a dual rotor and a sandwiched stator is introduced, including the structural design, fixation of the yokeless stator and segmented skew rotor structure. Then, the influence of anisotropic material and a fixed structure on stator modes is analyzed, including elastic modulus, shear model, the skew angle of slot and the thickness of stator yoke. Furthermore, a new non-equally segmented skew rotor structure is proposed and calculated for the reduction in vibration based on the multiphysics model. Three different segmented skew rotor schemes are compared to illustrate the influence of reducing vibration and noise. The predicted results show that the effect of the non-equally segmented skew rotor on reducing vibration is better than the other two schemes. Finally, a 120 kW AFPM motor is experimented with and the result matches well with the predicted data. The vibration performance of the AFPM motor with a dual rotor and sandwiched yokeless stator is revealed comprehensively. [ABSTRACT FROM AUTHOR]

China uses subsidies extensively to take a leading role in the global markets of green-tech products such as battery electric vehicles and wind turbines. Against the background of the current EU investigations into Chinese subsidies in these sectors, this article takes a careful look at the Chinese subsidy system and provides new data on direct government subsidies to leading Chinese producers of electric cars and wind turbines. Extensive government support has allowed Chinese companies to scale up rapidly, to dominate the Chinese market and to expand into foreign markets. The article concludes that the EU should use its strong bargaining power due to the single market to induce the Chinese government to abandon the most harmful subsidies. [ABSTRACT FROM AUTHOR]

Currently, excessive AC loss in the rectangular winding motor used for electric vehicles poses a significant challenge, necessitating effective measures to suppress the losses. This paper focuses on the Prius IV motor, employing a finite element two-dimensional model established using JMAG software. The influence of conductor material and the number of rectangular winding layers on motor AC loss under various operating conditions is thoroughly analyzed. Maintaining a constant number of rectangular winding layers, aluminum (Al) conductors replace copper (Cu) conductors in 2-layer, 4-layer, 6-layer, and 8-layer configurations, respectively. AC losses are compared among motors with 4-layer, 6-layer, 8-layer, and 10-layer Cu rectangular windings, all having identical slot dimensions. Subsequently, the 10-layer Al conductor scheme is chosen to optimize motor design. The results demonstrate an average reduction in AC loss up to 59.24% after motor optimization, further reducing motor manufacturing costs. [ABSTRACT FROM AUTHOR]

In astrodynamics, orbit cranking is usually referred to as an interplanetary transfer strategy that exploits multiple gravity-assist maneuvers to change both the inclination and eccentricity of the spacecraft osculating orbit without changing the specific mechanical energy, that is, the semimajor axis. In the context of a solar sail-based mission, however, the concept of orbit cranking is typically referred to as a suitable guidance law that is able to (optimally) change the orbital inclination of a circular orbit of an assigned radius in a general heliocentric three-dimensional scenario. In fact, varying the orbital inclination is a challenging maneuver from the point of view of the velocity change, so orbit cranking is an interesting mission application for a propellantless propulsion system. The aim of this paper is to analyze the performance of a spacecraft equipped with an Electric Solar Wind Sail in a cranking maneuver of a heliocentric circular orbit. The maneuver performance is calculated in an optimal framework considering spacecraft dynamics described by modified equinoctial orbital elements. In this context, the paper presents an analytical version of the three-dimensional optimal guidance laws obtained by using the classical Pontryagin's maximum principle. The set of (analytical) optimal control laws is a new contribution to the Electric Solar Wind Sail-related literature. [ABSTRACT FROM AUTHOR]

Using experiments by Sanya (18.3°N, 109.6°E) Incoherent Scatter Radar (SYISR) during 22 days, we first obtained the line‐of‐sight ion velocity in multiple directions, further calculated three‐dimensional vector velocity through least squares fitting, and subsequently derived northward neutral wind and electric fields from 150 to 500 km based on the momentum equation. In order to verify the reliability of the derived northward neutral wind and electric field, we used NCAR‐TIEGCM and HWM for comparative analysis. They had a good consistency in terms of diurnal variation and direction. The SYISR vertical ExB velocity during the daytime is larger than that of TIEGCM, and the direction reverses occur after 20:00 for both TIEGCM and SYISR. We further compared our wind data with that of ICON satellite. They showed a positive correlation of ∼0.62. We also used the ∆H method to verify our eastward electric field. They showed a roughly linear dependency, although the correlation coefficient is not very high. Plain Language Summary: In the low latitude ionosphere, neutral wind drives ions moving across the geomagnetic field line and generates electric field. Therefore, neutral wind and electric field are two key drivers in low latitude ionospheric dynamics. Monitoring both parameters is important for low latitude ionosphere investigation. However, measuring neutral wind and electric field, especially height profile in the F region, is very challenging and rare. In this paper, using the newly built Sanya Incoherent Scatter Radar, we have developed sophisticated algorithm to derive neutral wind and electric field from multiple beams SYISR measurements. Further evaluations show the data is reliable and therefore useful. Key Points: Northward neutral wind and electric field from 150 to 500 km are obtained using 22 days continuously SYISR observationsThe derived northward neutral wind and electric field are in good agreement with well‐known modelsThe results are further independently evaluated by ICON satellite and geomagnetism data [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Electric Solar Wind Sails (E-Sails) are a new type of spacecraft propellantless propulsion system that gathers its energy from solar wind protons and is potentially useful for interplanetary missions. Although optimal interplanetary trajectories have been the subject of thorough research, the substantial variability of the solar wind necessitates the adoption of active guidance strategies, an area that has received significantly less scholarly attention. This paper proposes guidance algorithms for E-Sails based on Model Predictive Control (MPC), a modern control methodology based on online re-planning of the trajectory. To this end, first, properties of E-sail time-optimal orbits are studied applying Pontryagin's Minimum Principle, and then time-optimal orbits for missions to Mars and Jupiter are computed via direct transcription methods. Next, solar wind perturbations are modeled, posing a challenging saturation problem due to their high variability. Guidance strategies based on Shrinking Horizon and Receding Horizon Model Predictive Control (RHMPC) are developed, analyzed and compared using Monte Carlo simulations, successfully implementing MPC to E-sail guidance. Lastly, the RHMPC strategy is successfully tested with accurate historical solar wind data from the WSA-Enlil model. • Solar wind fluctuations implies need of guidance in E-sail interplanetary missions. • Optimal planning for E-sails is performed using direct and indirect methods. • Control saturation due to solar wind pressure is reduced by leaving control margins. • Model predictive control guidance methods are compared with Monte Carlo analysis. • Receding horizon strategy in tested with semi-empirical historical solar wind. [ABSTRACT FROM AUTHOR]

The electric solar wind sail (E-sail) is a new propellant-free propulsion concept. The under-actuated and highly nonlinear features of E-sail systems pose a great challenge to their attitude controller design. Conventional control schemes may not be capable of dealing with this tough problem. To this end, a reinforcement learning (RL)-based control scheme, which can explore and obtain optimal policies in the absence of training datasets, is proposed for the attitude control of a barbell E-sail system. The barbell E-sail comprises two end satellites linked to an insulated confluence point through long and conductive tethers. The voltages of the two tethers can be individually modulated for attitude control. The system attitude dynamics is described using a nonsingular formulation. The control scheme has a two-stage design. In the first stage, an RL controller based on the Proximal Policy Optimization (PPO) algorithm is used to obtain an RL control strategy, which is emulated and updated by neural networks. In the second stage, the attitude feedback control is accomplished with low computation and energy consumption and fast convergence speed by performing a real-time mapping from the system state to the control output using the updated control strategy. Finally, the simulation results demonstrate that the proposed RL-based control scheme can effectively adjust the E-sail to the design attitude by regulating the tether voltage difference. The comparisons with the NMPC scheme also indicate that the developed control scheme can significantly reduce the computation time with control accuracy maintained. • Nonlinear dynamics and inherent constraints of the E-sail system are accounted for. • The reinforcement learning method is first applied to attitude control of the E-sail system. • Easy implementation, low computational cost and wide-range attitude adjustment are achieved. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Internet of Things (IoT) is introduced in systems with electrical machines, such as in electric drive systems, wind energy generating systems, and small and special machines, to remote monitor and control the operation for data acquisition and analysis. These systems can integrate with the equipment and retrofit the existing installations. At the end of the control loops there are always motors, or actuators, of big or small ratings, of rotating or linear movements, electrical or nonelectrical, which must produce the motion. This article analyses selected aspects of research and applications of IoT-based control in electric drive systems and of wind energy conversion systems with induction machines. Various applications and study cases of control systems of electrical machines with IoT technology are described. With the IoT-based control of induction machine systems operators can remotely monitor parameters and obtain accurate real-time feedback during fast changing duty cycle operation. Thus, IoT creates multipurpose instruments in the remote control of induction machines. The paper offers a comprehensive analysis of IoT-based control applications in the field of induction machines, with technical details of design, construction, experimental testing, and prototyping, that are useful to energy engineering specialists in the sector of electric drives and wind energy conversion systems. [ABSTRACT FROM AUTHOR]

• The combination of an electric solar wind sail and an electric thruster is proposed. • A multi-objective optimization algorithm is used to evaluate mission performance. • Circle-to-circle Earth-Mars and Earth-Venus transfers are used as test case scenarios. • A small propellant consumption allows transfer time to be significantly reduced. An electric solar wind sail is a propellantless propulsive system that generates thrust by exploiting the electrostatic interaction between solar wind ions and one or more charged tethers. Assuming a realistic near-term design in which the sail is composed of a limited number of tethers, the propulsive acceleration provided to the spacecraft is small. Moreover, according to a recent thrust model, the propulsive acceleration vector is constrained to lie in a cone centered on the outward radial direction with half-angle equal to about 20 degrees, resulting in a small circumferential component of the propulsive acceleration. In order to overcome these issues, a possible strategy consists in combining the electric sail with an electric thruster that provides a low thrust steerable around the circumferential direction. The effectiveness of such a combination is thoroughly analyzed in this work for deep-space heliocentric transfers. Transfer trajectories are obtained as outputs of a multi-objective optimization procedure, in which a suitable linear function of the flight time and the propellant consumption is minimized, considering different relative weights of the two competing requirements. Two exemplary case studies, consisting of Earth-Mars and Earth-Venus ephemeris-free circle-to-circle transfers, are presented to show the effectiveness of the proposed arrangement. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Polytechnic is the property of Journal of Polytechnic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Using Challenging Minisatellite Payload and the Republic of China Satellite‐1 observations, the response of ionospheric radial current (IRC) in the F region to the enhancement of merging electric field (Em) at different magnetic local times (MLT) is investigated. Possible physical mechanisms are discussed in terms of neutral wind, conductivity, and prompt penetration electric field (PPEF). The disturbance IRC (ΔIRC) increases in the upward (downward) direction in the daytime (nighttime) within 3 hr after Em enhancement. However, disturbance zonal winds increase westward (eastward) at 12–18 MLT (00–06 MLT). The reduced F region electron density may help weaken IRC at 06–12 MLT and 18–24 MLT. This work indicates that the daytime eastward (nighttime westward) PPEF drives equatorward (poleward) Hall current (JH) at low latitudes, resulting in both upward (downward) ΔIRC and eastward (westward) plasma drift at the F region magnetic equator. Plain Language Summary: The ionospheric radial current (IRC) flows vertically in the ionospheric F region near the magnetic equator, which plays an important role in the coupling process of E and F layers in the ionosphere. IRC is generally considered to be controlled by local neutral wind. The impact of solar wind electric field on IRC is still unknown. Previous studies have reported penetration of the high‐latitude electric field to the equatorial ionosphere. For the first time, we show that a sudden increase in the solar wind merging electric field leads to drastic changes in IRC in the F layer. The local time differences in the IRC changes could be explained by the penetration electric field effect rather than the neutral wind effect. Key Points: During Em enhancement, F layer radial current increases upward (downward), and plasma accelerates eastward (westward) at day (night)Local time differences in both radial current and plasma zonal drift are due to penetration electric field rather than F layer neutral windThe weakening of F layer radial current at 06–12 magnetic local times (MLT) and 18–24 MLT could be partly induced by the decrease in F layer electron density [ABSTRACT FROM AUTHOR]

A novel micro-solenoid resonator has been designed, simulated, and measured. The solenoid core consisted of a DuroidTM circuit board with a relative permittivity of 2.2. The resonator design incorporated four embedded copper vias with a radius of 125 µm and three surface conductors to form a rectangular coil. A pitch size of 250 µm was used for a 3.02 mm thick substrate. To enhance the resonator's performance at higher frequencies, a capacitance was introduced in series through the via. This additional capacitor effectively couples the inductance, resistance, and stray capacitance. The optimization of the quality factor was investigated through pole transfer analysis, resulting in an increased resonance frequency of 12.25 GHz and an elevated Q-factor of 306. Moreover, besides its very high Q-factor, this resonator offers a simplified design and easy integration. An analytical lumped circuit model was employed to investigate the design, and the measured S-parameters closely matched the analytical model and electromagnetic simulation results. The tuned resonator exhibited a superior quality factor compared to other micro-resonators. [ABSTRACT FROM AUTHOR]

Research on corona wind generation has been increasing in recent years because of its potential technological applications, particularly those related to improving heat transfer in small-scale devices. Since numerical simulations play a key role in the design of these applications, computationally efficient modeling of corona discharge is imperative. This work presents a new approach that allows rapid computation of the electrohydrodynamic (EHD) force density responsible for the generation of electric wind. Arbitrary electrode configurations can easily be dealt with in the model, since only the Laplacian electric field lines have to be determined numerically. Then, using approximated analytical approximations of the electric field intensity along the field lines, the spatial distribution of the current density and the space charge density can be easily determined. The model has been satisfactorily tested against experimental measurements of the current–voltage characteristic and the current density distribution on the cathode. Furthermore, the electric wind computed from the EHD force agrees quite satisfactorily with measurements carried out in different electrode configurations. Finally, the model has been applied to a new electrode configuration that has greater potential for heat transfer applications. [ABSTRACT FROM AUTHOR]

The electric solar wind sail (E-sail) spacecraft is a fuel-free propulsion system with promising potential in deep space explorations and solar activity monitoring missions. It is challenging to conduct attitude control for a full-scale flexible E-sail spacecraft due to its complex dynamical characteristics, including the spatial multi-scale, high-speed spinning, and large deformations. In this work, a double-loop attitude control strategy for the flexible E-sail spacecraft with high accuracy and efficiency is proposed. The E-sail spacecraft is firstly modeled by the referenced nodal coordinate formulation, where the rotations are described by the Lie group approach. A state-feedback controller developed from the Lyapunov stability theory is prescribed as the inner loop. The gain is obtained by solving a semidefinite programming problem with linear matrix inequality constraints, which is globally optimal and numerically reliable. A multi-variable proportional-integral-derivative controller is then introduced as the outer loop for flexibly enhancing the control performance. Several missions of the E-sail spacecraft, including attitude maneuvers on heliocentric and displaced non-Keplerian orbits, are studied to show that the desired attitude adjustments are accurately and efficiently achieved without exciting high-frequency oscillations. The double-loop control strategy has great prospects in designing and implementing orbital transformation and long-term stable Sun-orbiting missions. • A double-loop attitude control strategy for the full-scale flexible E-sail spacecraft. • The rotation is described by a Lie group approach without singularity. • The Lyapunov stability is adopted to model and calculate the inner loop gain. • The accuracy and adjustability are improved by the multi-variable PID controller. • The strategy is accurate and efficient for displaced non-Keplerian orbit missions. [ABSTRACT FROM AUTHOR]

Serious requirements are put forward for aircraft electric machines (EMs) in terms of weight and size indicators. To reduce the mass of EMs, it is possible to consider aluminum windings, the density of which is 3 times less than that of copper windings. However, due to the much lower electrical conductivity of aluminum (40% less than that of copper), the overall performance of EMs with the same output parameters with aluminum windings is higher. In this regard, there is an interest in the electrical industry in increasing the electrical conductivity of aluminum windings. This problem can theoretically be solved by using carbon nanotubes (CNTs) together with aluminum. This article presents the results of a study of additive windings of aircraft EMs from a powder alloy based on aluminum with CNTs. Visual inspection shows that aluminum windings with CNTs have a 7.4 times more porous structure. The results of experimental studies show that after adding CNTs, the electrical conductivity of aluminum windings became 35% lower and the resistance 50% higher compared to aluminum windings without CNTs. Thus, in the presented work, additive aluminum windings with CNTs exhibit much worse electromagnetic properties compared to aluminum windings without CNTs. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Studies on catching up and industrial leadership have often used market-related variables to evaluate the catch-up trajectories of latecomer countries and firms. In this study, we aim to enhance our understanding of these concepts by presenting an integrated market-technology framework. Using natural language processing techniques allows us to go beyond patent numbers and analyze patent novelty and impact as well as technological changes over time. In empirical case studies on wind energy and electric vehicles in China, Japan, and South Korea, we compare and identify country and sector-specific catch-up trajectories and potential catch-up traps. [ABSTRACT FROM AUTHOR]

An Electric Solar Wind Sail (E-sail) is a propellantless propulsion concept that extracts momentum from the high-speed solar wind stream to generate thrust. This paper investigates the performance of such a propulsion system in obtaining the transition from a prograde to a retrograde motion. The spacecraft is assumed to initially trace a circular heliocentric orbit of given radius. This particular trajectory, referred to as Circular Orbit Flip Trajectory (COFT), is analyzed in a two-dimensional mission scenario, by exploiting the capability of a medium-high performance E-sail to change the spacecraft angular momentum vector during its motion in the interplanetary space. More precisely, the paper describes a procedure to evaluate the E-sail optimal performance in a set of COFTs, by calculating their minimum flight times as a function of the sail reference propulsive acceleration. It is shown that a two-dimensional COFT can be generated by means of a simple steering law in which the E-sail nominal plane has a nearly fixed attitude with respect to an orbital reference system, for most of the time interval of the interplanetary transfer. [ABSTRACT FROM AUTHOR]

Modern electric machines are attracting great interest from the research community as a result of the increasing number of current applications, including electric vehicles and wind power generators, among others. Different machines, power converters, and control technologies are used, and the number of sensors is usually minimized to reduce the total cost of the system. Particularly interesting are the current and speed sensors, which are essential to the normal functioning of the entire system. This work analyzes different calibration techniques of these sensors, using as a case example a five-phase induction motor drive. Experimental results are included to show the influence of calibration techniques on the system analyzed. The obtained results can be extrapolated to any other similar system. [ABSTRACT FROM AUTHOR]

Based on the predictions of global 3D hybrid simulations, we present a new transport/acceleration path for escaped O+ ions in the upstream solar wind region resulting from the impact of a particular IMF tangential discontinuity (TD) with negative (positive) IMF Bz on the discontinuity's anti‐sunward (sunward) side. For O+ ions escaping to the duskside magnetosheath and with gyro‐radii larger than the TD thickness, when they encounter the TD, they can first go sunward into the upstream solar wind. They then gyrate clockwise to the pre‐noon side and get accelerated within the solar wind region and circulate back to the dawnside magnetosphere. These ions may be accelerated to well within the ring current energy range depending on the solar wind electric field strength. This new transport/acceleration path can bring some of the escaped ions into the inner magnetosphere, thus providing a new mechanism for generating an O+ ring current population. Plain Language Summary: O+ ions in the magnetosphere only come from the Earth's ionosphere. For O+ ions escaping the magnetosphere, scientists have been treating them as being lost. Using simulations that can describe the O+ ion's kinetic dynamics, we find that, due to the impact of a particular solar wind structure, some escaped O+ ions can circulate back to the magnetosphere via a transport path in the upstream solar wind region and some of them can even enter the inner magnetosphere. Additionally, they are also energized by solar wind electric field and thus can contribute to the ring current population. Therefore, this study shows a new journey of escaped O+ ions. Key Points: First global 3D hybrid simulations to investigate the fate of O+ ions after escaping the dayside magnetosphereNew transport/acceleration path for escaped O+ ions in upstream solar wind region after impact of an IMF tangential discontinuityNew transport/acceleration path brings some of escaped O+ ions back to the inner magnetosphere, contributing to O+ ring current pressure [ABSTRACT FROM AUTHOR]

In this study, the force generated by atmospheric positive and negative corona discharges was investigated using a simulation of a wire–cylinder configuration. We provided new insight into the atmospheric corona discharge by introducing a nonlinear force on the charged particles in the vicinity of the wire electrode. To elucidate the origin of both forces in corona discharges, we performed 2D simulations via COMSOL Multiphysics and MATLAB software. It was observed that the direction of nonlinear force is always from the wire to the cylinder regardless of the applied voltage polarity. It was illustrated that the corresponding nonlinear force of the positive corona is larger than that of the negative corona discharge. However, the span of the nonlinear force is greater in the negative corona discharge. The numerical simulation results showed that, in addition to the linear force (Coulomb force), a strong nonlinear force is generated around the wire electrode (powered electrode) that plays a complementary role in the production of electric wind caused by corona discharge. As this nonlinear force is limited to the vicinity of the wire electrode, it is possible to ignore the nonlinear force with a good approximation in the calculation of the total electrohydrodynamic force, but this force cannot be ignored in the process of forming the electric wind. [ABSTRACT FROM AUTHOR]

Our current knowledge of the geomagnetic poleward and equatorward boundary dynamics is limited, particularly, how deep those two latitudinal boundaries can extend into lower geomagnetic latitudes during magnetic storms. We want to understand the motion of the boundary because it is important in terms of the location and magnitude of the effects of geomagnetic disturbances associated with storms on the ground. In this study we derive spherical elementary ionospheric currents from ground magnetometer arrays covering North America and Greenland during six magnetic storms in 2015 and 2018. With two dimensional maps of the auroral region current, we select the equatorward boundary of the region 2 currents by‐eye and fit the boundary with an ellipse to derive the location of the equatorward boundary at magnetic midnight. We have obtained over 500 boundaries and find that the midnight boundary location varies between 45° and 66° magnetic latitude. We examine the influence of the interplanetary magnetic field (IMF), solar wind plasma, and geomagnetic indices on the location of the magnetic midnight equatorial boundary and find that the equatorial boundary location is best correlated with the IMF Bz, VBz, and the Sym‐H index. We demonstrate that as the Bz component becomes more negative, the magnitude of VBz increases, and the magnitude of the Sym‐H index increases, the magnetic midnight equatorial boundary shifts equatorward during periods of moderate to high geomagnetic activity. Plain Language Summary: Our current knowledge of the geomagnetic poleward and equatorward boundary dynamics is limited, particularly, how deep the equatorward boundary of the auroral current system can extend into lower magnetic latitudes during magnetic storms. In this study we use two dimension ionospheric current maps derived from ground magnetometer arrays covering North America and Greenland during magnetic storms in 2015 and 2018 to understand the variability of the equatorward boundary of the auroral currents at magnetic midnight. We examine the influence of the interplanetary magnetic field (IMF), solar wind plasma, and geomagnetic indices on the location of the magnetic midnight equatorial boundary and find that the magnetic midnight equatorial boundary location is best correlated with the Bz component of the interplanetary magnetic field, the solar wind electric field (VBz), and the Sym‐H geomagnetic index. We demonstrate that as the Bz becomes more negative, the magnitude of VBz increases, and as the magnitude of the Sym‐H increases the magnetic midnight equatorial boundary moves equatorward. Key Points: We show the temporal and spatial development of the region 2 current system equatorward boundary during magnetic stormsWe show that the equatorward boundary at magnetic midnight varies in magnetic latitude between 45° and 71° MLatWe demonstrate a correlation between the equatorward boundary location and IMF Bz southward, VBz, Sym‐H, and the ε parameter [ABSTRACT FROM AUTHOR]

Nd, Pr and Dy are critical raw materials as major components for rare earth permanent magnets (REPM). These are integral for several components placed for example within electric vehicles and wind turbine generators. REE primary production is mainly realized in China (~80%) and no REPM recycling industry has been established. Hydrometallurgical recycling routes lead to iron dissolution (66 wt. % Fe in REPM), while pyrometallurgical approaches that utilize SiO2 risk contaminating the produced iron phase. A two-step process is presented that (i) creates an FeOx-CaO-Al2O3-REE2O3 molten slag at 1500 °C through oxidative smelting and (ii) separates an iron-depleted slag phase (CaO-Al2O3-REE2O3) and a molten iron phase via carbothermic or metallothermic reduction at 1700–2000 °C. The slag has been designed as a selective collector phase and the REE2O3 loading within the bulk slag can reach up 25 wt. % REE2O3 at 1700 °C. The contained minerals within the slag exhibit >40 wt. % REE (a higher REE concentration than in the initial REPM). The resulting phases are characterized via ICP-OES, CS and SEM-EDX. In addition, the first results with regard to the downstream hydrometallurgical processing of the CaO-Al2O3-REE2O3 slag are presented aiming at the recovery of REE2O3, as well as of CaO and Al2O3. The latter compounds are to be reused during the first process step, i.e., the oxidative smelting of REPM. Slag leaching with methane sulfonic acid (MSA) and separation with alternative methods, such as solvent extraction, seems promising. Future work will include slag filtration with the aim to separate REE-rich solid phases (minerals) from the slag and also molten salt electrolysis of the produced REE2O3 oxides. [ABSTRACT FROM AUTHOR]

This study considers the design of a multi-link high-frequency circuit for calculating defective and defect-free insulation of mesh windings in order to increase the operational reliability of general-purpose electric machines. The object of research is mesh windings of electric machines. The problem to be solved: increasing the operational reliability of electric machines with general-purpose mesh windings by analyzing and modeling defects. The research results make it possible to model defects for the analysis of the state of insulation of electric machines with mesh windings. Special attention in the research was paid to induction motors with a worn-out resource, in particular, 4A80A4 UZ engine. The analysis includes phase-to-body capacitance, winding inductance, eddy current impedance, and winding impedance. Under the WN mode, a decrease in the impedance of the winding section from 3 % to the short-circuit mode was simulated; accordingly, the resonance frequencies for each case of 3 % were determined – 73990 Hz, short-circuit – 74450 Hz, as well as the corresponding input impedances 8938.7 and 8082.5. The corresponding voltage resonances and current resonances were also determined. Appropriate results were also given for the WG scheme. The results reported here relate to the design of the scheme and the research on the defects of the mesh winding. This contributes to the analysis of the state of insulation of mesh windings. The numerical data (resonant frequencies and input impedances) allow a better understanding of the behavior of windings in different states and degrees of defects. Given the research findings, it is possible to better identify and analyze potential defects in mesh windings, which in turn contributes to increasing the reliability of electric machines. The results of this study could be used in the field of diagnosis, service, and maintenance of electric machines with mesh windings. [ABSTRACT FROM AUTHOR]

Purpose: Nowadays there is still low awareness of creating specific supply chain hybrids in a planned manner. This paper focuses on a hybrid of the gresilient chain, which reflects the trend to act for the well-being of the environmental to eliminate disruptions in the flow of goods. The aim of the study is to determine the interdependence of the factors shaping the resilience of the supply chain and to determine which of them contribute the most to the creation of a green chain. Design/methodology/approach: AHP and DAMATEL were used as research tools. A study focused on the cognitive chain is extremely interesting, because it is a global chain in which the main coordinator is relatively small. The subject of the research is the international supply chain of a company that conducts research on engine oils, coolants and fuels for gas engines driving turbines, electric and wind turbines, hydraulic transmissions, etc. Findings: As a result, among other things, it was established, that speed is the factor that is most sensitive to the influence of other factors and, at the same time, the most important from the point of view of recipients. In addition, it was proven that redundancy is essential for creating resilience in the analyzed chain, while transparency is necessary for creating the green chain. It has also been shown that redundancy and cooperation work simultaneously to a great extent for the benefit of both chains. Research limitations/implications: Every supply chain requires a separate study. Practical implications: The results can help managers in implementing the gresilient strategy or in modifying it if it has already been implemented. The work carried out may contribute to the creation of a general matrix containing paths to the expected types of supply chains, taking into account the specificity of input and output connections. Social implications: Gresilient chains are part of the idea of corporate social responsibility. Originality/value: From the standpoint of building up resilience, this is an interesting case, because it is the discussed case does not fit into the concepts of popular models in which agility is promoted as the one that guarantees the resilience of the chain. The study is an expanding knowledge in the field of the gresilient chain, in which research is lacking due to the initial stage of science in this area. [ABSTRACT FROM AUTHOR]

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Coalescence/breakup characteristics of binary collisions of small water drops (dS = 0.4–1.8 mm diameter) with large drops (dL = 3–3.5 mm diameter) occurring in the absence/presence of horizontal electric field (EH) = 0, 100, and 300 kVm−1 have been investigated in a small vertical wind tunnel using a high‐speed digital camera. The coalescence efficiency (EC) of 0.299 observed for average diameters (dL = 3.2 mm, dS = 1.2 mm) in EH = 0 decreased to 0.244/0.211 when EH is increased to 100/300 kVm−1. The increase in the electric field reduces the probability of coalescence when Weber number (We) < 1. However, when We ≥ 1, an increase in We restricts the probability of coalescence. Our data, when plotted in the regime diagram in the We*‐p plane, delineates the collision outcomes in all‐electric field values but does show the overlapping of some data points in the adjacent categories. After a binary collision, the relaxation time for coalescence is higher than that for the breakup. Further, the relaxation time increases from the filament to sheet to disk mode of breakup in all‐electric field values. Fragment size distributions after the filament and sheet types of breakups differ and are differently affected by the applied electric field. Higher collision kinetic energy has a tendency to increase the number of fragments of the sizes between dL and dS. It is concluded therefore that, the effect of the electric field needs to be included in the estimation of drop growth and precipitation in clouds. Plain Language Summary: Effect of horizontal electric field (EH) = 0, 100, and 300 kVm−1 on the characteristics of binary collisions of small water drops (dS = 0.4–1.8 mm diameter) with large drops (dL = 3–3.5 mm diameter) has been investigated in a small vertical wind tunnel using a high‐speed digital camera. The coalescence efficiency (EC) of 0.299 observed for average diameters (dL = 3.2 mm, dS = 1.2 mm) in EH = 0 decreased to 0.244/0.211 when EH is increased to 100/300 kVm−1. The increase in the electric field reduces the probability of coalescence when a non‐dimensional parameter, Weber number (We) < 1. However, an increase in We restricts the probability of coalescence when We ≥ 1. After a binary collision, the relaxation time for coalescence is higher than that for the breakup and increases from the filament to sheet to disk mode of breakup in all‐electric field values. Fragment size distributions after the filament and sheet types of breakups differ. More violent collisions have a tendency to increase the number of fragments of the sizes between dL and dS. It is concluded therefore that, the effect of the electric field needs to be included in the estimation of drop growth and precipitation in clouds. Key Points: Horizontal electric field decreases (increases) coalescence (breakup) efficiency of colliding water dropsThe drop growth occurs mainly through the smaller size drops having small collision kinetic energyRelaxation time is higher for the coalescence than for the breakup and it increases from the filament to sheet to disk in electric field [ABSTRACT FROM AUTHOR]

The technology of Internet of Things (IoT) can be integrated with systems of electrical machines, for electric drives and wind and solar generation systems, and advance controlling and monitoring. This work presented recent research and progress of electrical drives with IoT technology, regarding design, operation, and trial of the control system for induction motors (ΙΜ). Also, the developed software code and hardware units for speed control were detailed and the results obtained from tests of performance of the ΙΜ integrated with IoT were described. With the IoT integration set-up, the operator can control the frequency values, obtain real-time feedback of the process, and monitor the system during varying loads in steady state. The operation of the ΙΜ system driven by inverter and its monitoring over IoT was proven to have high-accuracy speed control and increased efficiency at supersynchronous speeds. Thus, IoT establishes potentials to become a multipurpose tool in the industrial control of electric drives. This paper established one case study of an IoT set-up and control technique for IM, which is suitable for energy engineering experts in the field of IoT control of industrial equipment. [ABSTRACT FROM AUTHOR]

For a system simulating the dynamics of a single-link electromechanical manipulator, the problem of constructing a control voltage and determining the areas of final states is solved, the transition to any point of which from the initial state of rest using the constructed control occurs in a finite time without violating the specified restrictions on the voltage and heat release power in the winding of the rotor of the electric motor. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In micro-grids (MGs), renewable energy resources (RESs) supply a major portion of the consumer demand. The intermittent nature of these RESs and the stochastic characteristics of the loads cause a frequency stabilization issue in MGs. Owing to this, in the present manuscript, the authors try to uncover the frequency stabilization/regulation issue (FRI) in a two-area MG system comprising wind turbines (WTs), an aqua-electrolyzer, a fuel cell, a bio-gas plant, a bio-diesel plant, diesel generation (DG), ship DG, electric vehicles and their energy storage devices, flywheels, and batteries in each control area. With these sources, the assessment of the FRI is carried out using different classical controllers, namely, the integral (I), proportional plus I (PI), and PI plus derivative (PID) controllers. The gain values of these I, PI, and PID controllers are tuned using the recently proposed smell agent optimization (SAO) algorithm. The simulation studies reveal the outstanding performance of the later controller compared with the former ones in view of the minimum settling period and peak amplitude deviations (overshoots and undershoots). The SAO algorithm shows superior convergence behavior when tested against particle swarm optimization and the firefly algorithm. The SAO-PID controller effectively performs in continuously changing and increased demand situations. The SAO-PID controller designed in nominal conditions was found to be insensitive to wide deviations in load demands and WT time constants. [ABSTRACT FROM AUTHOR]

In this paper, a multi-objective allocation and scheduling of wind turbines and electric vehicle parking lots are performed in an IEEE 33-bus radial distribution network to reach the minimum annual costs of power loss, purchased grid energy, wind energy, PHEV energy, battery degradation cost, and network voltage deviations. Decision variables, such as the site and size of wind turbines and electric parking lots in the distribution system, are found using an improved golden jackal optimization (IGJO) algorithm based on Rosenbrock's direct rotational (RDR) strategy. The results showed that the IGJO finds the optimal solution with a lower convergence tolerance and a better (lower) objective function value compared to conventional GJO, the artificial electric field algorithm (AEFA), particle swarm optimization (PSO), and manta ray foraging optimization (MRFO) methods. The results showed that using the proposed method based on the IGJO, the energy loss cost, grid energy cost, and network voltage deviations were reduced by 29.76%, 65.86%, and 18.63%, respectively, compared to the base network. Moreover, the statistical analysis results proved their superiority compared to the conventional GJO, AEFA, PSO, and MRFO algorithms. Moreover, considering vehicles battery degradation costs, the losses cost, grid energy cost, and network voltage deviations have been reduced by 3.28%, 1.07%, and 4.32%, respectively, compared to the case without battery degradation costs. In addition, the results showed that the decrease in electric vehicle availability causes increasing losses for grid energy costs and weakens the network voltage profile, and vice versa. [ABSTRACT FROM AUTHOR]

Copyright of Romanian Journal of Civil Engineering / Revista Română de Inginerie Civilă is the property of Matrix Rom and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A longstanding challenge with high Mg content Al alloys is the trade-off between corrosion resistance and strength, because the stabilization temperature is lower than the recrystallization temperature corresponding to a no stabilization temperature range. Herein, a stabilization temperature range is found with an excellent match of strength and corrosion resistance of high Mg content Al alloy via pulsed electric current. The stimulated atomic diffusion rate resulted in discontinuous grain boundary precipitates, along with a lower electric wind force development rate to maintain dislocation strengthening. These results provide insights into developing high-performance Al-Mg alloys by the pulsed electric field treatment. The pulsed electric current treatment provides a new measure to develop high-performance Al alloys with high Mg content, improving the corrosion resistance while ensuring dislocation strengthening. [ABSTRACT FROM AUTHOR]

The electrically assisted forming (EAF) is a hybrid manufacturing process that utilizes electric current energy to improve the productivity and efficiency of the forming process. Many studies have been accomplished to investigate the effect of process parameters on its forming abilities, including pulse current effect, grain size, and current duration. There is currently a lack of agreement on the underlying mechanisms of the electroplastic effect to the formability of metallic materials through EAF, specifically on the Joule heating and electric wind's contributions. One promising solution to this dilemma is the application of computer simulation techniques for a better understanding of the physics of EAF. Therefore, this paper provides a brief review of the previous research studying the modeling of EAF and offers new solutions aiming to further the understanding of the underlying physics of this process through computer simulation approaches. [ABSTRACT FROM AUTHOR]