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Planning maintenance of medium voltage overhead lines is one of the most important issues in the studies on power distribution network, which will prevent and reduce unwanted interruption. In this paper, long‐term maintenance of medium voltage networks was planned by multi‐objective function, including an extended mixed‐integer linear model to optimize costs, energy not supplied (ENS), and average interruption duration index (SAIDI). In addition, the uncertainty about the annual growth rate of the load, the increase in the cost of goods and services and the increase in the selling price of energy as well as various constraints are all included in the desired objective function, which is one of the main innovations of this paper compared to other published studies. To apply the uncertainties, information gap decision theory (IGDT) has been used, and to solve the objective functions, LP‐Metric method has been used. The proposed method was implemented on the standard 11‐bus RBTS network by MATLAB and GAMS. The results showed that three different long‐term maintenance plans proposed here lead to the optimization of the annual maintenance costs of network, reduction in ENS and interruption, and increase in the reliability of the network based on the uncertainty of each feeder. [ABSTRACT FROM AUTHOR]

The fast-growing influence of grid-interfaced photovoltaic (PV) networks makes it necessary to adhere to grid-code (GC) regulations. These regulations mandate that PV systems inject active power both during and after the grid fault occurrence, as well as provide reactive current to the grid during voltage dips, in order to prevent power system stability concerns. In this context, two novel control schemes have been proposed in this paper for grid-connected photovoltaic networks that can support low-voltage ride-through (LVRT). The proposed control techniques have been demonstrated to be simple and efficient in the event of severe voltage dips, i.e., work up to a voltage drop of 90% of the nominal grid voltage. Our first approach involves an enhanced reactive current injection strategy that provides reactive power support to the power grid during voltage dips without any additional devices. The control structure is comprised of a voltage level estimator and a reactive current controller. The voltage level estimator obtains power grid voltage, while the reactive current controller computes active−reactive current commands. It is particularly noteworthy that the proposed scheme generates active current as much as possible according to the voltage dips and tracks the active current reference correctly, where conventional strategies fail to cope. The second control method for LVRT presented in this research work involves using hardware, specifically a crowbar. The use of a crowbar is the most straightforward method to provide support to the power system, bypassing over-current during voltage dips and keeping the current within the normal converter rating. The control strategies proposed in this paper are validated in MATLAB/Simulink under symmetrical and unsymmetrical severe voltage dips as well as grid voltage harmonics, and a detailed comparison study with a state-of-the-art PQ-based fault-ride-through controller has been conducted. [ABSTRACT FROM AUTHOR]

This paper presents a novel, state-of-the-art predictive control architecture that addresses the computational complexity and limitations of conventional predictive control methodologies while enhancing the performance efficacy of predictive control techniques applied to three-level voltage source converters (NPC inverters). This framework's main goal is to decrease the number of filtered voltage lifespan vectors in each sector, which will increase the overall efficiency of the control system and allow for common mode voltage reduction in three-level voltage source converters. Two particular tactics are described in order to accomplish this. First, a statistical approach is presented for the proactive detection of potential voltage vectors, with an emphasis on selecting and including the vectors that are most frequently used. This method lowers the computational load by limiting the search space needed to find the best voltage vectors. Then, using statistical analysis, a plan is presented to split the sectors into two separate parts, so greatly limiting the number of voltage vectors. The goal of this improved predictive control methodology is to reduce computing demands and mitigate common mode voltage. The suggested strategy's resilience is confirmed in a range of operational scenarios using simulations and empirical evaluation. The findings indicate a pronounced enhancement in computational efficiency and a notable diminution in common mode voltage, thereby underscoring the efficacy of the proposed methodology. This increases their ability to incorporate renewable energy sources into the electrical grid. [ABSTRACT FROM AUTHOR]

The paper deals with the non-destructive experimental testing of the reinforced concrete beams under progressive corrosion. A series of experiments using electrical potential, ultrasound and low-frequency vibrations techniques are reported. Electrical potential and natural frequencies were used to characterise and monitor the corrosion process at its initial state. The P-wave velocity measurements were proved to be effective in quantitative assessment of the level of corrosion as it progresses. The possibility of early detection of damage using a proposed damage index and diagnostic framework is promising for possible applications in the non-invasive diagnostics of reinforced concrete elements. [ABSTRACT FROM AUTHOR]

Context: The compounds of the "565" parent ring structure have received much attention from researchers because of their excellent detonation performance. In the present study, 81 derivatives were designed by introducing different substituents based on 6-dinitrophenyl-5,6,7,8-tetrahydro-4-imidazo[4,5-e]furazano[3,4-b] pyrazine (DIOP), which is a compound of the parent ring structure of 565, and the performance of these derivatives, such as the electronic structure, energy gap, heat of formation, and detonation performance, were investigated. Among these energy-containing derivatives, the density ranges from 1.70 to 2.17 g/cm3, the detonation velocity ranges from 8.01 to 10.26 km/s, and the detonation pressure ranges from 27.99 to 49.88 GPa. Through comprehensive analysis of several properties of DIOP derivatives, it was found that the oxygen balance of derivatives with the -ONO2 group was greater than zero and close to zero, while the oxygen balance of derivatives with other groups was almost all less than zero. Among them, G8 (D = 10.1 km/s, P = 47.72 GPa), H8 (D = 10.11 km/s, P = 47.92 GPa), and I8 (D = 10.26 km/s, P = 49.88 GPa) had higher detonation velocity and pressure among all derivatives, and their impact sensitivity was better than RDX. Therefore, three potential high-energy and less sensitive energy-containing derivatives, G8, H8, and I8, were screened out. The intramolecular interactions of the three derivatives were further analyzed, and it was found that there were intensive van der Waals interactions and significant spatial steric effects within the molecules, which had a positive effect on reducing the shock sensitivity of the compounds. Moreover, the three derivatives have a large degree of stacking, which leads to a high density. Methods: All calculations in this paper are performed using Gaussian16 based on density functional theory. Firstly, the structures of the derivatives were optimized at the level of B3LYP-D3/6-311G**, and then single-site energy calculations were carried out at the level of M06-2X-D3/def2-TZVPP, to reveal the effects of single substituents versus multiple substituents and isomerism on the properties of the DIOP-based energetic derivatives. Multiwfn was used to plot the density of states (DOS) of the derivatives and to calculate the molecular surface electrostatic potential at 0.001 e/Bohr3 electron density, 0.25 Bohr lattice spacing surface. [ABSTRACT FROM AUTHOR]

This paper introduces a new algorithm designed to address the challenge of distribution network reconfiguration, employing the tabu search metaheuristic in conjunction with the voltage drop concept. Distinguishing itself from existing methods, our proposed approach not only utilizes voltage drop for obtaining the initial solution but also introduces a novel technique for generating a candidate solution neighborhood. This method leverages both randomness and voltage drop, ensuring a smooth and steady descent during algorithm execution. The primary goal of our algorithm is to minimize active power losses within distribution networks. To validate its effectiveness, the proposed method underwent testing on three commonly referenced distribution systems: the 33-Bus, 69-Bus, and 94-Bus systems, widely acknowledged in the literature. A pivotal aspect of our work involves the synergy of the tabu search algorithm with a combination of both random and deterministic methods for generating neighbors. This strategic amalgamation plays a crucial role, enabling rapid execution while consistently yielding high-quality solutions. Additionally, the adoption of the electric distance method for generating the initial solution adds significant value, offering a commendable solution with minimal computational effort. Comparative assessments against other algorithms documented in the literature underscore the superior efficiency of our proposed algorithm. [ABSTRACT FROM AUTHOR]

Li-N2 batteries present a relatively novel approach to N2 immobilization, and an advanced N2/Li3N cycling method is introduced in this study. The low operating overpotential of metal–air batteries is quite favorable to their stable cycling performance, providing a prospect for the development of a new type of battery with extreme voltage. The battery system of Li-N2 uses N2 as the positive electrode, lithium metal as the negative electrode, and a conductive medium containing soluble lithium salts as the electrolyte. In accordance with its voltage-distribution trend, a variety of lithium-nitrogen molecule intermediates are produced during the discharge process. There is a lack of theoretical description of material changes at the microscopic level during the discharge process. In this paper, the first-principles approach is used to simulate and analyze possible material changes during the discharge process of Li-N2 batteries. The discharge process is simulated on a 4N-graphene anode substrate model, and simulations of its electrostatic potential, Density of States (DOS), HOMO (Highest Occupied Molecular Orbital) and LUMO (Lowest Unoccupied Molecular Orbital) aspects confirm that the experimentally found Li3N becomes the final stabilized product of the Li-N2 battery. It can also be seen in the density of states that graphene with adsorption of 4N transforms from semiconducting to metallic properties. In addition, the differential charge also indicates that the Li-N2 material has a strong adsorption effect on the substrate, which can play the dual role of electricity storage and nitrogen fixation. [ABSTRACT FROM AUTHOR]

The main purpose of the paper is to show how a magnetoresistive (MR) element can work as a current sensor instead of using a Wheatstone bridge composed by four MR elements, defining the concept of a magnetoresistive shunt (MR-shunt). This concept is reached by considering that once the MR element is biased at a constant current, the voltage drop between its terminals offers information, by the MR effect, of the current to be measured, as happens in a conventional shunt resistor. However, an MR-shunt has the advantage of being a non-dissipative shunt since the current of interest does not circulate through the material, preventing its self-heating. Moreover, it provides galvanic isolation. First, we propose an electronic circuitry enabling the utilization of the available MR sensors integrated into a Wheatstone bridge as sensing elements (MR-shunt). This circuitry allows independent characterization of each of the four elements of the bridge. An independently implemented MR element is also analyzed. Secondly, we propose an electronic conditioning circuit for the MR-shunt, which allows both the bridge-integrated element and the single element to function as current sensors in a similar way to the sensing bridge. Third, the thermal variation in the sensitivity of the MR-shunt, and its temperature coefficient, are obtained. An electronic interface is proposed and analyzed for thermal drift compensation of the MR-shunt current sensitivity. With this hardware compensation, temperature coefficients are experimentally reduced from 0.348%/°C without compensation to −0.008%/°C with compensation for an element integrated in a sensor bridge and from 0.474%/°C to −0.0007%/°C for the single element. [ABSTRACT FROM AUTHOR]

The distributed direct current (DC) power system relies heavily on the cascaded DC–DC converter that employs a common bus to connect multiple DC–DC converters. The first stage of the cascaded DC–DC converter is responsible for injecting power from a renewable source or a battery into the DC bus. Conversely, the second stage connects a load to the DC bus, creating a constant power load (CPL) that consumes constant power regardless of the supply voltage. This behavior often causes disturbances and instabilities, leading to unwanted oscillations that adversely impact the quality of the input current. To address this issue, this paper proposes an active current ripple-damping technique that extracts the fundamental of the inductor current. When combined with the super-twisting sliding mode control, this approach effectively mitigates input current ripples and enhances the stability of the CPL. The key to this approach is the sliding surface selection, which requires a cleaned inductor current from the second boost converter. Experimental results are provided to demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

This paper addresses the issue of LED short-circuit fault detection in signaling and lighting systems in the automotive industry. The conventional diagnostic method commonly implemented in newer vehicles relies on measuring the voltage drop across different LED branches and comparing it with threshold values indicating faults caused by open circuits or LED short circuits. With this algorithm, detecting cases of a few LEDs short-circuited within a branch, particularly a single malfunctioning LED, is particularly challenging. In this work, two easily implementable algorithms are proposed to address this issue within the vehicle's control unit. One is based on a mathematical prediction model, while the other utilizes a neural network. The results obtained offer a 100% LED short-circuit fault detection rate in the majority of analyzed cases, representing a significant improvement over the conventional method, even in scenarios involving a single malfunctioning LED within a branch. Additionally, the neural network-based model can accurately predict the number of failed LEDs. [ABSTRACT FROM AUTHOR]

Paper Spray (PS) is an ambient ionisation technique that is conceptually simple, economical, direct and versatile. In its simplest form, the procedure for operation relies on the application of an electric potential to a triangular-shaped paper substrate with the addition of an extraction/spray solvent to generate charge droplets, without requiring any pneumatic assistance. Despite its promise and rapidly growing popularity, there are some practical challenges associated with PS implementation with scope to enhance its performance further. One such challenge relates to only a small fraction of the Taylor cone expansion being sampled at the MS inlet. In this work we propose a new arrangement for PS, which retains the inherent advantages of this popular technique without introducing additional variables, by using an ambient ion focusing lens that is held at the same potential as the paper substrate. A thorough investigation, consisting of visual spray inspection, electric field simulations and analytical evaluation, including analysis of paracetamol from saliva, shows that ambient ion focusing can provide up to a 50% improvement in spray stability, 60% increase in signal intensity and a 30% improvement in detection limits for routine paper spray mass spectrometry analysis. [Display omitted] • Ion lens arrangement provides a simple means to produce a stable and collimated beam profile. • Ambient ion focusing leads to improvements in spray stability, signal intensity, accuracy and detection limits. • Analysis of paracetamol in saliva is demonstrated using ambient ring lens paper spray mass spectrometry. [ABSTRACT FROM AUTHOR]

In this paper, high-performance indium gallium oxide (IGO) thin-film transistor (TFT) with a double-gate (DG) structure was developed using an atomic layer deposition route. The device consisting of 10-nm-thick IGO channel and 2/48-nm-thick SiO2/HfO2 dielectric was designed to be suitable for a display backplane in augmented and virtual reality applications. The fabricated DG TFTs exhibit outstanding device performances with field-effect mobility (μFE) of 65.1 ± 2.3 cm2V−1 s−1, subthreshold swing of 65 ± 1 mVdec−1, and threshold voltage (VTH) of 0.42 ± 0.05 V. Both the (μFE) and SS are considerably improved by more than two-fold in the DG IGO TFTs compared to single-gate (SG) IGO TFTs. Important finding was that the DG mode of IGO TFTs exhibits the nearly temperature independent μFE variations in contrast to the SG mode which suffers from the severe remote Coulomb scattering. The rationale for this disparity is discussed in detail based on the potential distribution along the vertical direction using technology computer-aided design simulation. Furthermore, the DG IGO TFTs exhibit a greatly improved reliability with negligible VTH shift of − 0.22 V under a harsh negative bias thermal and illumination stress condition with an electric field of − 2 MVcm−1 and blue light illumination at 80 °C for 3600 s. It could be attributed to the increased electrostatic potential that results in fast re-trapping of the electrons generated by the light-induced ionization of deep level oxygen vacancy defects. [ABSTRACT FROM AUTHOR]

In the case of certain chemical compounds, especially organic ones, electrons can be delocalized between different atoms within the molecule. These resulting bonds, known as resonance bonds, pose a challenge not only in theoretical descriptions of the studied system but also present difficulties in simulating such systems using molecular dynamics methods. In computer simulations of such systems, it is often common practice to use fractional bonds as an averaged value across equivalent structures, known as a resonance hybrid. This paper presents the results of the analysis of five forms of C60 fullerene polymorphs: one with all bonds being resonance, three with all bonds being integer (singles and doubles in different configurations), one with the majority of bonds being integer (singles and doubles), and ten bonds (within two opposite pentagons) valued at one and a half. The analysis involved the Shannon entropy value for bond length distributions and the eigenfrequency of intrinsic vibrations (first vibrational mode), reflecting the stiffness of the entire structure. The maps of the electrostatic potential distribution around the investigated structures are presented and the dipole moment was estimated. Introducing asymmetry in bond redistribution by incorporating mixed bonds (integer and partial), in contrast to variants with equivalent bonds, resulted in a significant change in the examined observables. [ABSTRACT FROM AUTHOR]

In this paper, the electro-mechanical behavior of a flexoelectric nanobeam, considering the surface effect, is studied with an induced electric potential. Based on the modified strain gradient theory and Hamilton's variational principle, the governing differential equations of the nanobeam and the corresponding boundary conditions are obtained. The exact deflection solution of the flexoelectric nanobeam is derived from static bending. The relationship between the induced electric potential, including the surface effect, and the angle of the end of the cantilever beam is presented. Moreover, the characteristic equation of natural frequency is obtained by using a separate variable method under an open circuit with surface electrodes and an induced electric potential condition (OCI). The simulated results indicate the electro-mechanical response of the cantilever beam can be controlled by adjusting the flexoelectric coefficient, residual surface stress, and material length scale parameters of strain gradient theory. The free end of the beam with a platform phenomenon is also found by setting the appropriate parameters. The results also show that the residual surface stress and the ratio of beam thickness to material length scale parameters have a more significant effect on the effective frequency shift of the flexoelectric nanobeam. Therefore, considering the induced electric potential and surface effect is of great significance for the study of flexoelectric nanobeam sensors. [ABSTRACT FROM AUTHOR]

The synthesis of gold(III) and gold(I)–gold(III) complexes with phosphide bridges is still a matter that requires solutions for their marked instability, in spite of the affinity of this metal in both oxidation states for phosphorous donor ligands. In the course of our studies, we realized that the presence of perhalophenyl groups of the type pentafluorophenyl or 3,5-dichlorotrifluorophenyl in the complexes gives rise to an increase in their stability that eases their isolation and structural characterization. In this paper, we describe two new fully characterized neutral compounds of this type to extend the knowledge on this family of compounds, [{Au(C6Cl2F3)2}2(µ-PPh2)2] (1) and [{Au(C6Cl2F3)2(µ-PPh2)2Au}2] (2). In this work, we analyze the role of the perhalophenyl groups in the stability of these complexes by using quantum chemical topology methodologies, specifically employing an analysis of the non-covalent interactions (NCIs) in real space and evaluating the electrostatic potential surfaces (ESP). Our findings reveal the existence of appreciable π-stacking interactions among the perhalophenyl and phenyl groups in both compounds, significantly contributing to the stability of the systems. [ABSTRACT FROM AUTHOR]

Permanent magnet (PM) motors are gaining prominence in subsea applications such as drilling, pumping, and boosting for oil and natural gas extraction. These motors are gradually replacing traditional induction motors. However, starting and operating PM motors at low speeds under heavy loads poses significant challenges. This is because of unknown initial rotor positions and resistive voltage drops due to the presence of a sinewave filter, transformer, and long cable. An unknown rotor position may result in temporary reverse speed, which may cause a loss of synchronism; therefore, initial rotor position estimation is preferable. Additionally, addressing the voltage drop issue requires careful voltage compensation to avoid transformer core saturation. In this paper, an enhanced V / H z starting of a PM motor is proposed with initial position detection (IPD) and voltage compensation to start the motor reliably with a heavy load. The proposed control method is verified with controller hardware in the loop (C-HIL) real-time simulation using a Typhoon HIL-604 emulator and a Texas Instruments TMS320F28335 digital signal processor (DSP) control card. [ABSTRACT FROM AUTHOR]

• A novel piezoelectric semiconductor cylindrical shell is proposed. • The principle of virtual work is applied for the governing equations. • 2D behaviors in static bending and forced vibration are considered. • Mechanical displacements and electric potentials are sensitive to the doping level. • New structure and analytical solutions are helpful for sensing and energy harvesting. This paper examines the mechanically induced electric potential and charge redistribution in a piezoelectric semiconductor cylindrical shell employing first-order shear deformation theory. The two-dimensional governing equations and corresponding boundary conditions are simultaneously derived through a principle of virtual work method and the fundamental lemma of the calculus of variation. For the application of electronic devices, static bending and forced vibration analyses of an open cylindrical shell under locally distributed normal forces are analytically solved with the derived theoretical model. The effects of doping level on electric potentials and mechanical displacements are presented. An interesting result shows that doping levels can alter the peak position of the zeroth-order electric potential. In addition, the first three order natural frequencies of the shell under time-harmonic load are identified, and the doping level is found to have an inhibiting effect on the first natural frequency. All the numerical results are beneficial for optimizing the design and performance of cylindrical shell-shaped sensors and energy harvesters. [ABSTRACT FROM AUTHOR]

Context: To explore the impact of OGs (OGs) on formaldehyde (HCHO) adsorption by modified activated carbon, this paper studied the influence of OGs on HCHO adsorption characteristics, varying the groups including ester, carboxyl, and hydroxyl. Employing density functional theory (DFT), the effects of various OGs on the structure of N-doped activated carbon through GGA-PBE exchange-correlation functionals by Materials Studio combined with Gaussian software. The types of weak interactions during the adsorption process were calculated by RDG, elucidating the mechanism through which the three OGs affect HCHO adsorption on N-doped activated carbon. The dynamic adsorption process of HCHO was simulated by molecular dynamics (MD). The influence and proportion of OGs on HCHO adsorption were subsequently analyzed using van der Waals and electrostatic interactions, determining differences in formaldehyde adsorption effects across OG types. The carboxyl group exhibits the most robust synergistic adsorption effect on the modified activated carbon. There is a notable alteration in the position and distribution of electrostatic potential extremes observed following carboxyl modification. The calculation results show that the adsorption energy of hydroxyl groups on modified activated carbon is the highest, at −5.07 kcal/mol, with a transfer charge of 0.014 e. Following the introduction of carboxyl groups, the proportion of electrostatic interactions escalated from the initial 24% to 38%. This study will provide new ideas for guiding the design of activated carbon for efficient adsorption of formaldehyde. Methods: The modified activated carbon fragments of three OGs were constructed by Materials Studio and Gaussian software, and the surface electrostatic potential polarity and area distribution, charge change, adsorption energy, and transferred charge of each molecular fragment were calculated. Moreover, cell models of OGs with the same dimensions were constructed to simulate the adsorption amount, heat of adsorption, interaction energy, radial distribution function, and hydrogen-bonding interactions for methane at room temperature and pressure. The results were consistent with the DFT simulations. [ABSTRACT FROM AUTHOR]

In the next decade, the demand for copper is expected to grow by 25%, posing a challenge for mining facilities to increase their production by opening new mines or upgrading existing ones. To optimize the electrical infrastructure of mining facilities, the integration of flexible AC transmission systems (FACTSs) can be instrumental in mitigating voltage stability issues that may arise during the installation of new gearless motor drives (GMDs). The purpose of this paper is to conduct a comparative analysis of the dynamic performance of static VAR systems (SVSs) as a means of enhancing voltage stability in mining expansion projects, particularly in the context of the integration of new GMDs into the system. This paper presents a case study of an existing three crushing-line mine configuration that has been upgraded with two new GMD systems. The primary contribution of this research is a comprehensive methodology designed to enhance the stability of a mining system through the integration of an SVS, which includes the sizing of the SVS system, an analysis of costs, as well as a determination of the required installation surface and optimal placement of the SVS within the system. The simulation results conclusively demonstrate the effectiveness of the SVS systems in reducing the voltage drop by 2% upon activation of new GMDs, as well as mitigating the adverse impact of transient disturbances on the system. Specifically, the first oscillation voltage peak value is improved by 3.5%, following a three-phase short circuit of 1 second duration, while overvoltage is reduced by 1% in response to sudden load changes. When compared with the system without an installed SVS, these findings highlight the significant advantages and benefits of integrating SVSs into mining operations. [ABSTRACT FROM AUTHOR]

This paper presents a detailed study of the energy savings that can be achieved through residential appliances by implementing conservation voltage reduction (CVR). The computed energy savings are derived from the ZIP coefficients of a load model (static) under varying voltage conditions that represent the power consumed by each appliance tested. Multiple studies have shown energy savings at the substation level but not at the level of a specific residence and appliance; hence, the latter is the focus of this analysis. The appliances are determined based on the type of heating and cooling loads, and the daily duration of use for each appliance, which contributes to the total monthly consumption that is billed for a household are included in this study. Energy savings in Malaysia has been a focus of many current studies, and this study is the first attempt to achieve energy savings through the implementation of CVR. No published work has compared individual appliances that truly benefits from CVR, and this is addressed in this study. The main contribution of this study is that it provides very detailed and measured data that are used to analyze and generate energy savings for very specific residential appliances intended to meet every 1% voltage drop. The load model is developed for the common household appliances in Malaysia, and then a voltage reduction study is applied to the appliances as well as the Malaysian distribution networks. Here, we also provide insight for performing voltage reduction at an electric vehicle (EV) charging station in Malaysia. The results of this study should serve as a foundation for all practicing utilities engineers to address the issue of CVR in Malaysia. The CVR factors for residential, commercial, and industrial networks in Malaysia are also published in this paper. [ABSTRACT FROM AUTHOR]

The main contribution of this paper is the assets of the current and voltage ripples in a buck converter with an LED load. The results indicate that the ripples are different and that it is possible to reduce the passive filter concerning the model of the LED as a simple resistance. The paper presents the design and simulation of a buck converter as a power supply for an LED lamp. Modeling the LED as a resistor and a voltage source (SVRM), the equations to calculate the components of the circuit using the SVRM model are presented, where the Fourier series and phasors are used to calculate the output filter. The equations are validated with SPICE simulations. The results indicate that the SVRM model for the LED load affects the calculation of the output filter of the buck converter as well as the voltage and current ripples, making it a more precise design alternative to the proposed development. [ABSTRACT FROM AUTHOR]

The breaking capacity of rated current is one of the important indexes to evaluate the performance of circuit breakers, which is usually measured experimentally and cannot be analyzed in terms of the arcing characteristics of the opening process. Simulation methods based on the magnetohydrodynamic (MHD) model of the arc can be used to obtain the macroscopic motion of the arc within the interrupter and the interaction of the arc with the contacts, walls, and splitter plates. Therefore, this paper focuses on the arc interruption characteristics' underrated current in low voltage circuit breakers by MHD simulation. A more accurate and effective field-circuit coupling MHD simulation model of low voltage circuit breaker products is developed in this paper. A nonlinear conductivity model of the sheath layer is considered to better simulate the near-pole voltage drop and bending processes after the arc has been cut by the splitter. The time-dependent magnetic field generated by the arc is considered in the calculation. Additionally, the real-time parameters of the external circuit are coupled to reflect the evolution of the arc characteristics under the action of the external circuit. The simulation results intuitively and clearly show the evolution of the arc during the breaking process. Through this, an arc extinguishing chamber can be designed to effectively regulate the arc interruption characteristics, thereby improving the breaking capacity of the circuit breaker. The accuracy and efficiency of the proposed simulation method is verified by experiments. This method can be extended to the performance analysis of AC/DC low voltage circuit breakers. [ABSTRACT FROM AUTHOR]

This paper presents an innovative approach to wireless cellular stimulation therapy through the design of a magnetoelectric (ME) microdevice. Traditional electrophysiological stimulation techniques for neural and deep brain stimulation face limitations due to their reliance on electronics, electrode arrays, or the complexity of magnetic induction. In contrast, the proposed ME microdevice offers a self-contained, controllable, battery-free, and electronics-free alternative, holding promise for targeted precise stimulation of biological cells and tissues. The designed microdevice integrates core shell ME materials with remote coils which applies magnetic temporal interference (MTI) signals, leading to the generation of a bipolar local electric stimulation current operating at low frequencies which is suitable for precise stimulation. The nonlinear property of the magnetostrictive core enables the demodulation of remotely applied high-frequency electromagnetic fields, resulting in a localized, tunable, and manipulatable electric potential on the piezoelectric shell surface. This potential, triggers electrical spikes in neural cells, facilitating stimulation. Rigorous computational simulations support this concept, highlighting a significantly high ME coupling factor generation of 550 V/m·Oe. The high ME coupling is primarily attributed to the operation of the device in its mechanical resonance modes. This achievement is the result of a carefully designed core shell structure operating at the MTI resonance frequencies, coupled with an optimal magnetic bias, and predetermined piezo shell thickness. These findings underscore the potential of the engineered ME core shell as a candidate for wireless and minimally invasive cellular stimulation therapy, characterized by high resolution and precision. These results open new avenues for injectable material structures capable of delivering effective cellular stimulation therapy, carrying implications across neuroscience medical devices, and regenerative medicine. [ABSTRACT FROM AUTHOR]

For mining engineering and geological engineering, the deformation and fracture of coal and rock are the essential causes of dynamic disasters. In this paper, the loading experimental system was established on gas-bearing coal, to study the internal relationship between the spatial distribution of EP and the development process of damaging localization on coal mass. The results indicated the temporal response of EP signal could reflect the stress state and damage degree of gas-bearing coal, showing the precursor feather when coal mass failed. Particularly, when the stress dropped suddenly, the EP signal has a sudden mutation, and the acoustic emission (AE) signal suffered the pulsed increase, while the crack grew and expanded rapidly. Furthermore, when local severe damage occurs inside the coal mass, there was abnormal EP spatial distribution with high-value or dense contours in these zones, where simultaneously AE rupture events frequently occurred, and cracks expanded and gathered. The characteristics of EP spatial distribution can reveal the development process of coal mass damaging localization. Meanwhile, the mentioned zones with abnormal EP distribution above are hazard sources inducing coal mass’s instability and failure. The study results provide the foundational research work of fine forecasting on coal and gas outburst disaster hazard. [ABSTRACT FROM AUTHOR]

Flexoelectricity, referring to the electrical polarization generated by strain gradients, is an electromechanical coupling phenomenon in all dielectric materials. Based on the Kirchhoff plate theory, this paper investigates the influence of flexoelectricity on the electromechanical coupling response of piezoelectric circular nanoplates with different electric boundary conditions. Using the variational principle and Gibbs free energy, the governing equations and boundary conditions of piezoelectric nanoplates are derived. The analytical solutions of the deflection, polarization, and induced electric potential are obtained. The results show that the flexoelectric effect is size-dependent and has a more significant influence on the electrostatic responses than the piezoelectric effect at the nanoscale. The results also show that the induced electric potential due to the flexoelectric effect may be helpful for sensing or energy harvesting designs. [ABSTRACT FROM AUTHOR]

In this paper, we propose a system of nonlinear equations for the electric field potential and temperature, which describes the process of heating the semiconductor elements of an electrical board followed by thermal breakdown. For this system of equations, we prove the existence of a classical solution that is not extendable in time and also obtain sufficient conditions for the solution to blow up in finite time. [ABSTRACT FROM AUTHOR]

The existing active-type voltage arc suppression methods do not consider the influence of line voltage drop, which leads to the existence of large fault residual current at the fault point for low-resistance grounding fault occurring in the distribution network and affects the reliable extinguishing of the fault arc. In this paper, an active inverter is used to inject a compensating current to the neutral point of the system before and after the fault, and the distance between the fault point and the bus is calculated, then the reference value of the neutral point voltage which controls the fault point voltage to zero can be obtained. A double closed-loop control strategy of current inner loop and voltage outer loop is used to track the voltage reference value. The simulation results show that the proposed method is independent of the exact zero-sequence admittance value, and not only has a good arc suppression effect under different fault conditions, but also can effectively suppress the harmonic components of the fault current. [ABSTRACT FROM AUTHOR]

This paper presents an electrical endurance design method of multi-operation isolators using semi-physical simulation via algebraic multigrid iteration (AMG). The mathematical model of Magnetohydro dynamics (MHD) is built by simultaneous equations of mass conservation, horizontal momentum, vertical momentum, conservation equation of ion energy, as well as electromagnetic equation. In addition, the physical properties of plasma medium in non-solid state, including thermal conductivity, electrical conductivity, dielectric density over temperature are used to dynamically update the coupled multi-physics. The established model can thus be solved via AMG, which is a fast iterative method for solving large-scale sparse normal equations based on geometric multigrid method. The finite element method (FEM) is likewise conducted under the various operating conditions to seek arc plasma temperature, the electric potential, electromagnetic distribution. The electrical endurance reliability can be reckoned using the maximum likelihood estimator of the desired shape parameters and scale parameters of Weibull's distribution, by integrating analogical semi-physical simulation. The physical experiment is carried out which involves electrical safety test, the withstanding voltage test, also called Hipot test or dielectric test, arc ignition test, resistance test. It proves that the proposed method can realize the endurance design of electrical equipment with high convergence efficiency and low residual error, and is especially suitable for the analysis under multiple working conditions. [ABSTRACT FROM AUTHOR]

Based on the nonlocal strain gradient theory and flexoelectricity theory, a new model of transversely isotropic piezoelectric rectangular nano-plate subjected to a distributed load is proposed. The nonlocal effect, strain gradient effect and flexoelectric effect are all considered in the novel model. The governing equation and different boundary conditions for a clamped nano-plate under closed circuit and open circuit states are derived by Hamilton principle. Based on the new model, the electro-mechanical responses of piezoelectric nano-plate are numerically analyzed. When the dimensionless nonlocal scale coefficient is smaller than 3, both the central deflection and the central electric potential show significant size dependence. The nonlocal effect causes the nano-plate to be softened while the strain gradient effect makes it stiffened. Compared with the piezoelectric effect, the impact of the flexoelectric effect on the central electric potential plays a dominant role. In addition, the electric potential increases from each lateral edge to the center symmetrically, reaching a maximum at the central point. This paper elucidates the competitive relationship among the influencing effects and concurrently discovers that these effects have a comparable magnitude of impact on the electro-mechanical responses of nano-plate. [ABSTRACT FROM AUTHOR]

In electromagnetism, materials with a polarization density P → or a magnetization density M → are known to exhibit a bound surface charge density σ b = P → · n ̂ or a surface current density κ → b = M → × n ̂ , respectively, where n ̂ is the unit vector perpendicular to the material boundary surface, directed outward. These expressions can be obtained from volume integrations for the electric potential V, or the magnetic vector potential A → , in which the integrals are restricted to the material volumes delimited by their respective boundaries. In that case, applying the divergence theorem leads to surface integrals on material boundaries and to the above-mentioned surface quantities. In this paper, a simple derivation is presented, which shows that both σb and κ → b are included in the expressions for the volume charge or current densities, provided that the divergence and curl operators are evaluated at the boundary so as to account for discontinuities at interfaces. [ABSTRACT FROM AUTHOR]

This paper presents a time-of-flight image sensor based on 8-Tap P-N junction demodulator (PND) pixels, which is designed for hybrid-type short-pulse (SP)-based ToF measurements under strong ambient light. The 8-tap demodulator implemented with multiple p-n junctions used for modulating the electric potential to transfer photoelectrons to eight charge-sensing nodes and charge drains has an advantage of high-speed demodulation in large photosensitive areas. The ToF image sensor implemented using 0.11 µm CIS technology, consisting of an 120 (H) × 60 (V) image array of the 8-tap PND pixels, successfully works with eight consecutive time-gating windows with the gating width of 10 ns and demonstrates for the first time that long-range (>10 m) ToF measurements under high ambient light are realized using single-frame signals only, which is essential for motion-artifact-free ToF measurements. This paper also presents an improved depth-adaptive time-gating-number assignment (DATA) technique for extending the depth range while having ambient-light canceling capability and a nonlinearity error correction technique. By applying these techniques to the implemented image sensor chip, hybrid-type single-frame ToF measurements with depth precision of maximally 16.4 cm (1.4% of the maximum range) and the maximum non-linearity error of 0.6% for the full-scale depth range of 1.0–11.5 m and operations under direct-sunlight-level ambient light (80 klux) have been realized. The depth linearity achieved in this work is 2.5 times better than that of the state-of-the-art 4-tap hybrid-type ToF image sensor. [ABSTRACT FROM AUTHOR]

• A simplified lattice boltzmann model is developed for simulating two-phase electro-hydrodynamics (EHD) flow. • The model reflects a direct update of macroscopic variables within lattice boltzmann framework. • The mode performs well in studying large-conductivity-ratio two-phase EHD flow problems. • We delineate regions in the (C r ,P r)-plane in which the role of electric force components on electric force is marked. This paper proposes a numerical scheme within the lattice Boltzmann framework for effective simulations of two-phase electro-hydrodynamic (EHD) flows, in which the simplified multiphase lattice Boltzmann method serves as the flow solver and a leaky dielectric model is utilized to recover electric potential equation. The resultant formulations present direct evolution of macroscopic variables, due to which the present method outperforms the conventional lattice Boltzmann method in terms of memory cost and boundary treatment. Numerical validations are first carried out under the same parametric conditions as the benchmarking experimental studies with the conductivity ratio ranging from 0.03 to 1000, demonstrating that the present method is a practical and accurate tool to study large-conductivity-ratio two-phase EHD flows in scientific applications. Through the comparison with previous theoretical and numerical studies, the performance of the present method is further evaluated by varying physical parameters such as electric capillary number, electric field strength, interfacial tension, and electrical properties of liquids. The good agreements with the reference data confirm the accuracy and robustness of the proposed method. Additional studies of the dynamics of a deformed droplet in uniform electric field are carried out using the validated method. Specifically, we conduct a close numerical examination on the effect of the electrical conductivity ratio and permittivity ratio on the electric forces, and highlight the role of the dielectric electrophoretic force and the Coulomb force on the electric forces the deformation of a leaky dielectric droplet in the electrical conductivity ratio and the permittivity ratio phase diagram. [ABSTRACT FROM AUTHOR]

In this paper, the size-dependent free vibration of a piezoelectric semiconductor plate is investigated within the framework of the nonlocal theory and piezoelectric semiconductor theory. The displacement, electric potential and perturbation of electron concentration are provided based on the first-order shear deformation theory. The two-dimensional governing equations including the equations of motion, Gauss's law and current continuity condition are obtained by introducing the plane stress assumption and integrating the three-dimensional governing equations along the thickness direction. The vibration of a simply supported piezoelectric semiconductor plate is achieved by solving the governing equations. Some numerical examples are presented to show the effect of the initial electron concentration, nonlocal parameter, plate thickness, length to thickness ratio and length to width ratio on the vibration of the piezoelectric semiconductor plate. The results indicate that the damping characteristic of the piezoelectric semiconductor plate can be effectively designed by adding the appropriate initial electron concentration. Also, both the nonlocal parameter and the geometric property have an important effect on the natural frequency and damping characteristic of the system. [ABSTRACT FROM AUTHOR]

Context: This paper studied MP-B36 interactions through DFT. MP molecules were observed to have a substantial tendency to be adsorbed through their N heads onto B36 at its edge, based on large adsorption energy values. The B atoms at the edges of B36 nanosheets showed higher reactivity than the internal B atoms toward MP. The electronic properties changed upon MP adsorption. The MP-B36 configurations of the highest stability underwent an energy gap reduction of 11–47%. Natural bond orbital (NBO) analysis and molecular electrostatic potential (MEP) analysis were used to evaluate the MP-B36 interaction. Methods: The configurations were subjected to geometric optimization at the TPSSH/6–31 + G(d) level of theory, at which frequency analysis was carried out to evaluate the stationary points. These configurations were neutral (Q = 0). The electronic properties of MP dramatically changed upon its interaction with B36 nanosheets. The stable configurations underwent an energy gap reduction, suggesting a chemical signal. The MP molecules were observed to be effectively adsorbed onto the B36 edge within aqueous phases. The MP-B36 configurations were estimated to have relatively large dipole moments. This demonstrated that MP-B36 systems were soluble and dispersed within solar media (e.g., water). It was concluded that B36 nanosheets could serve as efficient MP carriers in nanomedical drug delivery applications. [ABSTRACT FROM AUTHOR]

The necessity for environmentally friendly transportation systems has prompted the proliferation of electric vehicles (EVs) in low-voltage (LV) distribution networks. However, large-scale integration and simultaneous charging of EVs can create power quality challenges for the distribution grid. It is therefore important to assess the impact of connecting EVs for charging in existing distribution networks and determine the hosting capacity (HC) of such a network. This paper uses a deterministic time-series method and stochastic method based on a simplified Monte Carlo simulation to estimate the HC of single-phase and three-phase EV charging, respectively, for a South African low-voltage distribution network containing 21 households. Voltage drop and equipment loading are the performance indices (PI) considered for the impact assessment and HC estimation in this study. The impact assessment result confirms that increasing EV charging penetration will result in a corresponding movement of the PIs toward the allowable limits. The results show that the HC is 5–8 three-phase EVs charging simultaneously for the worst-case scenario and 9–13 EVs for the best-case scenario. Furthermore, the single-phase HC for the popular 3.7 kW EV charger is 15 and 8 EVs for the best-case and worst-case scenarios, respectively. The result showing the seasonal variation in HC and for other EV charging power is also presented. The difference in HC for the worst-case and best-case scenarios portrays the effect that the location of charging has on the HC. [ABSTRACT FROM AUTHOR]

In this paper, the challenges of determining the optimal location and size of the flexible alternating current transmission systems (FACTS) devices on the transmission system are solved. The FACTS devices are placed and sized optimally using three optimizations: genetic algorithm, simulated annealing, and flower pollination algorithm (FPA). Three FACTS devices, capacitor, Static VAR Compensator (SVC), and static synchronous compensator (STATCOM), are determined for two parameters: location and size to solve the multi-objective problem. The simulation results are analyzed to find the best optimization and FACTS device to improve the voltage profile and simultaneously lower the active power loss of the system. To investigate its effectiveness, the proposed approach was tested using two test systems, Pakistan's transmission network and IEEE 30 bus. Conducted in three cases for the real system data, the first case being the base case with a 50% uniformly increase in both active and reactive power of the load bus voltage, the second case with a 50% increase in only the active power, and the third case with a 50% increase in reactive power. The comparison of this optimization has shown that FPA performed better than the other algorithm and with the fastest convergence rate. The simulation results demonstrate that STATCOM was effective to minimize the losses while enhancing the voltage profile. Also, the Wilcoxon test is applied to confirm the efficiency of the STATCOM device. [ABSTRACT FROM AUTHOR]

Power converter technologies have become vital in various applications due to their efficient management of electrical energy. With the growing prominence of renewable energy sources such as solar and wind, the high penetration of power electronic converters has been justified. However, ensuring power quality has emerged as a significant challenge for grid-connected power converters. The divergence from the ideal sinusoidal waveform in terms of magnitude and frequency impacts both grid-side currents and voltages. Several studies have proposed solutions to address power quality issues at the load side. The advancement of power converters has been fueled by the development of high-performance microprocessors and the emergence of high-speed switching devices, such as SiC-MOSFETs. This paper focuses on the design of voltage source converters, particularly those based on SiC-MOSFET semiconductor devices. The article presents the design of H-Bridge cells, discusses two-level voltage source converters based on cascade H-Bridge cells in a parallel configuration with experimental fault analysis, addresses the seven-level voltage source converter topology, and explores the design and experimental results of the matrix converter. The findings underscore the importance of considering the entire converter design for improved performance at high switching frequencies. The article concludes by summarizing the main outcomes and implications of this research. [ABSTRACT FROM AUTHOR]

As a technique to control the voltage drop at network peak periods and voltage rise at middays when a high number of rooftop photovoltaic systems exist in a low-voltage feeder (LVF), two or more neighboring LVFs can be coupled. To add voltage controllability to the coupling point, a distribution static compensator (DSTATCOM) can be installed. An important issue for such a system is its operation under short-circuit conditions in one of the LVFs and relevant protection aspects. This paper investigates the performance of such a system under fault conditions and presents a protection scheme that can achieve the desired operation of the system, under short-circuit faults in either of the LVFs. The performance of the system of coupled LVFs is investigated by numerical analysis in MATLAB while the dynamic feasibility of the proposed technique is validated by simulation studies in PSCAD/EMTDC. [ABSTRACT FROM AUTHOR]

In this paper, analytical solutions for Rayleigh wave in a transversely isotropic piezoelectric semiconductor (PSC) substrate with a covering layer of different type doping are obtained. The PN junction (called also the depletion layer), which is created by the diffusion and drifting due to the different doping type of the substrate and the covering layer, can be considered as an electrically gradient layer between the covering layer and the substrate. Making use of the state transfer equation method, the transfer matrix of the state vector of the depletion layer is derived mathematically. Based on the numerical calculations, we investigate the physical influences of the covering layer, electric boundary conditions and doping concentrations on the dispersion and attenuation, and the effects of PN junction on the wave-mode shapes. Our results show that the semiconductor will slow the Rayleigh waves and induce the attenuation. Both the phase velocity and attenuation are dependent upon the frequency. The existence of PN junction has less influences on the dispersion and attenuation but relatively large influences on the wave-mode shapes, especially, on the electric potential, carriers concentration, electric displacement, and the current density of carriers. [ABSTRACT FROM AUTHOR]

This paper deals with the study of vibrations in piezothermoelastic microbeam resonator using modified couple stress theory. The closed form expressions for deflection, electric potential and temperature distribution for the beam have been derived. The solution is presented under clamped-free boundary condition. Analytical expressions for thermoelastic damping, frequency shift and attenuation are obtained and effects of electric potential, thermal relaxation time, temperature, beam dimensions and couple stress have been depicted graphically. The numerical results are presented with the help of MATLAB programming software in case of a lead zirconate titanate (PZT)-5A material. [ABSTRACT FROM AUTHOR]

Negative-sequence current is required to be intentionally injected to support the power grid or compensate the imbalanced load in asymmetrical faults utilizing STATCOM. However, the extreme compensation range of negative-sequence current injection becomes complicated when grid voltage becomes asymmetrical. This article presents a novel off-line strategy for negative-sequence current compensation under two typical kinds of asymmetrical grid faults — single-phase voltage drop and double-phase voltage drop, with the following two benefits simultaneously: maximizing negative current compensation capacity; avoiding iterations and reducing computation burdens. In this paper, the mechanism of DC voltage balancing among three phases in STATCOM is analyzed and a new identification method of negative-sequence current compensation range is explored out. To simplify the calculation, this paper takes the ratio of negative-sequence reactive (Iq-) and active (Id-) current as a variable (s). In this way, the relationship between the extreme compensation range, asymmetrical voltage sag depth of power grid h is drawn with MATLAB. Different from the previous iterative method, the off-line identification method is applied to avoid huge iterations. By fitting the curve, the precise ranges of negative-sequence current compensation under different asymmetrical grid faults are approximated as simple polynomials, thus significantly reducing the computation burdens. Simulation and experimental results verify the practicability of the proposed compensation method. [ABSTRACT FROM AUTHOR]

The paper deals with a simplified approach to evaluate the frequency of damage of low voltage apparatus powered by a in housing HV/LV transformer against overvoltages due to nearby lightning flashes (source of damage S4 according to IEC 62,305 standard). The approach is based on computer simulations with validated models according to the current state of the art. The paper evaluates: the overvoltages stressing the HV/LV transformer due to lightning-induced over-voltages on the supplying HV overhead line; the voltage transferred to low voltage circuit through the power transformer and the influence of the transformer characteristics and of the LV circuits feeding the apparatus; the influence of the characteristics and the number of LV circuits on the frequency of damage of the apparatus. The different contributions to the voltage at the apparatus terminals, namely, the voltage transferred by the HV/LV transformer and the voltage induced by lightning current in the circuit downstream the transformer, are recognized. The voltage drop along the earthing system between the points where the transformer and the apparatus are earthed is, in the case considered, not effective because the apparatus and the transformer are bonded at the same point to the earthing system of the electrical installation. Even if these voltage components exhibit different shape and time at peak, for safety, they are added. When the resulting voltage is higher than the rated impulse voltage of apparatus insulation, damage of apparatus occurs. The evaluation allows to conclude that the frequency of damage of the LV apparatus supplied by circuits in a multipolar cable is about a thousand times lower than the one relevant to circuits in plastic conduit. If the tolerable frequency of damage of the LV apparatus is kept in the range of 0.01 damage/year, the adoption of protection measures against overvoltages caused by the source S4 is practically not necessary, except for the case of long circuits in conduit, powered by long HV overhead lines in areas with high values of lightning flash density. As this matter has not yet been considered in the IEC 62305 standard series, the results presented in this paper will be useful in the light of the revision of requirements of this standard. [ABSTRACT FROM AUTHOR]

In this paper, to better reveal the surface effect and the screening effect as well as the nonlinear multi-field coupling characteristic of the multifunctional piezoelectric semiconductor (PS) nanodevice, and to further improve its working performance, a magneto-mechanical-thermo coupling theoretical model is theoretically established for the extensional analysis of a three-layered magneto-electro-semiconductor coupling laminated nanoplate with the surface effect. Next, by using the current theoretical model, some numerical analyses and discussion about the surface effect, the corresponding critical thickness of the nanoplate, and the distributions of the physical fields (including the electron concentration perturbation, the electric potential, the electric field, the average electric displacement, the effective polarization charge density, and the total charge density) under different initial state electron concentrations, as well as their active manipulation via some external magnetic field, pre-stress, and temperature stimuli, are performed. Utilizing the nonlinear multi-field coupling effect induced by inevitable external stimuli in the device operating environment, this paper not only provides theoretical support for understanding the size-dependent tuning/controlling of carrier transport as well as its screening effect, but also assists the design of a series of multiferroic PS nanodevices. [ABSTRACT FROM AUTHOR]

The basis for judging whether the battery pack is balanced is generally whether the voltage of the battery cell is consistent because the voltage of the battery cell is very easy to obtain. However, when the voltage of battery cells is the same and the battery management system (BMS) turns off the equalization, it will get poor balance performance. In this paper, a new balancing strategy is proposed, while the calculated state of charge (SOC) difference between the battery cells instead of the voltage reaches the set value, the BMS turns on or off, and the difference in the SOC between battery cells is obtained by adding a small amount of calculation to the difference in voltage between battery cells, due to the long balancing time of the battery, the battery will enter a steady state at the end of balancing, based on the voltage difference of battery cell, the voltage drop generated by the balancing current on the ohmic resistance and polarization resistance is added, combined with the open circuit voltage (OCV)‐SOC curve, the difference in battery voltage can be indirectly converted into a difference in SOC. This strategy will appropriately delay the battery balancing time to make up for the drop in the voltage of the balanced battery cell after the BMS turns off the balancing. In this paper, the proposed strategy and performance are analyzed in detail, the experimental platform is designed to verify, and the battery pack is tested under static and discharge conditions. Although the equalization goal is the same voltage between battery cells, using the voltage‐based equalization strategy, the voltage difference between the battery cells is 8 and 6 mV, respectively, while the strategy proposed in this paper is 2 and 3 mV, which has better performance. [ABSTRACT FROM AUTHOR]

This paper presents an online method to monitor the conditions of the substation grounding grid. The proposed method utilizes phase-to-ground faults occurring in downstream feeders as test current sources and the neutral of a specially selected feeder as the electrode for GPR (ground potential rise) measurement. The measured fault currents and GPRs are then used to estimate substation grounding grid impedance. The method, once established, can monitor the grounding grid impedance continuously and automatically, and the trend of the impedance change can be observed. As a result, the proposed method can yield much more reliable information on the substation grounding conditions. The method also overcomes many disadvantages of the offline methods. The proposed idea, algorithm, and hardware setup are described in the paper. Factors contributing to measurement errors are investigated in detail. [ABSTRACT FROM AUTHOR]

This paper is concerned with a linear theory of thermopiezoelectricity in which the second gradient of the displacement, the second gradient of the electric potential and the second temperature gradient are included in the classic set of independent constitutive variables. The present paper is based on Green–Naghdi thermomechanics. The introduction of the entropy flux tensor leads to constitutive equations that depend on the second temperature gradient. The fundamental boundary-initial-value problems are formulated and the uniqueness of the solution is studied. Two applications of the theory are presented. We study the problem of a concentrated charge density acting in an unbounded region, as well as the effects of a concentrated heat source. [ABSTRACT FROM AUTHOR]

Design and application of LED driver with isolated CUK converter for 10W is realized in this paper especially for automotive purposes. The advantage of isolated CUK topology from conventional CUK topology is to have electrical isolation with supply and load and providing same polarity output. Besides, power LED models including constant voltage and exponential model are obtained and employed in simulation study. Furthermore, maximum current limitation of power LED is provided via dsPIC30f4011 microcontroller. Also, power switch is operated by 100 kHz switching frequency, and connection of the power LED driver to the source provided by LC with parallel damping filter, whose noise reduction shown by application as well. Thanks to the experimental set up and simulations, proving the desired results provided by the converter is shown by the measurement of LED currentvoltage, input voltage-current. Simulation results also verifies application. Moreover, it is shown that exponential power LED model provides more accurate results than constant voltage model. [ABSTRACT FROM AUTHOR]

This research paper aims to investigate the optimal design of grading rings for high-voltage polymeric insulators in an actual power transmission system, with a focus on improving the electrical representation of the insulator strings. One such subsidiary accessory commonly used with porcelain and polymer insulator strings is the grading ring, which is employed to improve the electric field and voltage distribution surrounding the insulator string. The efficiency of insulator strings can be enhanced by grading rings, as they facilitate a more linear potential division along the strings. The design parameters of grading rings significantly influence their performance on insulator strings. In this study, we examine the optimal design of the grading rings of high-voltage polymer insulators, since no uniform design methodology has been developed for high-voltage polymer insulators, and their optimization is currently the subject of many research studies. The electric field on an outdoor polymeric insulator is examined using finite element method (FEM) software and COMSOL Multi-Physics program. A 2D model is utilized to simulate a 220 kV polymeric insulator. The effectiveness of high-voltage polymeric insulators greatly depends on the dimensions and locations of the grading rings. Therefore, the impacts of the radius of the grading ring and that of its tube and the tube's vertical position are thoroughly investigated, under dry and humid conditions. To achieve this objective, a search algorithm is employed to adjust the dimensions and locations of the grading ring. The optimization approach in this study is based on determining the maximum electric field across the insulator surface, while ensuring that it remains below the corona initiation level. [ABSTRACT FROM AUTHOR]

The thermospheric neutral density response to the 7–9 September 2017 storms is investigated based on the Swarm satellite observations and the thermosphere‐ionosphere‐electrodynamic general circulation model (TIEGCM) simulation. The Swarm data depicted a prominent interhemispheric asymmetry (IHA) in the afternoon sector during the second storm, a feature that was yet explained. Driven by realistic high‐latitude electric potential and electron precipitation patterns, the TIEGCM is able to reproduce the observed storm‐time neutral density response. The TIEGCM simulation reveals that the differences in the traveling atmospheric disturbances (TADs) is largely responsible for the observed IHA in the neutral mass density response at low and middle latitudes, whereas the difference in mean molecular mass between the two hemispheres may contribute to the IHA in neutral density at higher latitudes. The IHAs in TADs and mean molecular mass are attributed to the IHA in Joule heating dissipation on the night and dawn sides. Plain Language Summary: During geomagnetic storms, thermospheric neutral density can increase drastically due to intense heat inputs. Enhanced neutral density increases the air drag on satellites which could lower their orbits and lead to faster atmosphere reentering of satellites. In addition, enhanced neutral mass density may cause larger uncertainties in orbit prediction which increases the risk of collisions with other space objects. Therefore, it is essential to improve the understanding of storm‐time neutral density variations to improve satellite operations. Recent satellite observations have revealed that thermospheric neutral mass density response can be interhemispherically asymmetric even under equinox conditions when the background density in the two hemispheres is comparable. This paper presents a case study of such an event based on data analysis and numerical simulations to investigate the physical mechanisms behind this intriguing phenomenon. The event took place on 7–9 September 2017 and the most prominent interhemispheric asymmetry of neutral density occurred in the afternoon sector. Our study found that the interhemispheric asymmetry during this event results from the differences in the generation, propagation and interaction of globally propagating atmospheric waves, namely traveling atmospheric disturbances, as well as the difference in mean molecular mass between the northern and southern hemispheres. Key Points: Thermosphere‐ionosphere‐electrodynamic general circulation model captures the observed interhemispheric asymmetry (IHA) in the neutral density response to the 7–9 September 2017 geomagnetic stormsThe IHA in the neutral density response results from the IHA in traveling atmospheric disturbances and mean molecular massThe observed IHA in the neutral density response is not caused by direct Joule heating dissipated at the same local time [ABSTRACT FROM AUTHOR]

The fault‐induced delayed voltage recovery (FIDVR) and short‐term voltage instability (STVI) phenomena appear in networks with high penetration of induction motor loads because the increase in requested reactive powers of these loads prevents the voltages from quickly returning to their pre‐fault levels. Load shedding (LS) is one of the ways to deal with FIDVR and STVI and reduce the imbalance between the generation and demand of reactive power. Under‐voltage (UV) relays that disconnect loads during voltage drop cannot effectively deal with this phenomenon because of their inability to detect the effective loads on the reduction of FIDVR and STVI severities. Therefore, the operation of UV relays during these phenomena causes unnecessary load disconnection, and the interference of their operations with FIDVR and STVI must be avoided. This paper presents two wide‐area approaches based on network and loads parameters, the first of which deals with the most critical FIDVR, and the second tries to simultaneously handle critical FIDVRs of all buses. Also, bus prioritization for LS during STVI has been addressed. Simulation results revealed the better performance of the proposed approaches than the previous ones in terms of the amount of LS and the number of selected buses for LS. [ABSTRACT FROM AUTHOR]