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Accurate quantification of the uncertainty in the mechanical characteristics of dielectric solids is crucial for advancing their application in high-precision technological domains, necessitating the development of robust computational methods. This paper introduces a Conditional Generation Adversarial Network Isogeometric Analysis (CGAN-IGA) to assess the uncertainty of dielectric solids' mechanical characteristics. IGA is utilized for the precise computation of electric potentials in dielectric, piezoelectric, and flexoelectric materials, leveraging its advantage of integrating seamlessly with Computer-Aided Design (CAD) models to maintain exact geometrical fidelity. The CGAN method is highly efficient in generating models for piezoelectric and flexoelectric materials, specifically adapting to targeted design requirements and constraints. Then, the CGAN-IGA is adopted to calculate the electric potential of optimum models with different parameters to accelerate uncertainty quantification processes. The accuracy and feasibility of this method are verified through numerical experiments presented herein. [ABSTRACT FROM AUTHOR]

A novel microfluidic device containing a bi-gap electrode pair is presented in this paper, and it is capable of continuously separating three different populations of particles using dielectrophoresis. A mixture of 5, 10, and 20 μm polystyrene particles is focused by a sheath flow and then separated based on size after flowing over a bi-gap electrode pair. A new solver is developed in OpenFOAM to investigate the effects of various parameters such as the flow rate, gaps, and electrode pair angles to achieve an appropriate configuration of the bi-gap electrode pair for efficient particle separation. Based on the numerical simulation results, three different configurations of bi-gap electrode pairs are fabricated. The paths of three populations of polystyrene particles under various operating conditions are experimentally examined and compared with numerical results. Then, by examining the purity of the separated particles with three different electrode configurations at different flow rates, the performance of the device is experimentally investigated. The results showed that by employing the proposed electrode configuration, at a maximum flow rate of 100 μL h−1 (25 μL h−1 for the sample), particles are separated precisely (with more than 99% purity for all particles at desired outlets) using a 20 Vpp sinusoidal electric potential with a frequency of 100 kHz. This novel microfluidic device is thus a practical device for continuously separating three different populations of particles/cells according to size in a heterogeneous admixture. [ABSTRACT FROM AUTHOR]

Abstract: In this article, existing technologies of switchable liquid crystal gratings and their limitations are discussed. A new mode ferroelectric liquid crystal with its unique characteristics is presented, which shows great potential for grating use. Some possible fabrication procedures and results are also presented in this paper. [ABSTRACT FROM AUTHOR]

The excitation energy transfer (EET) process for photosynthetic antenna complexes consisting of subunits, each comprised of multiple chromophores, remains challenging to describe. The multichromophoric Förster resonance energy transfer theory is a popular method to describe the EET process in such systems. This paper presents a new time-domain method for calculating energy transfer based on the combination of multichromophoric Förster resonance energy transfer theory and the Numerical Integration of the Schrödinger Equation method. After validating the method on simple model systems, we apply it to the Light-Harvesting antenna 2 (LH2) complex, a light harvesting antenna found in purple bacteria. We use a simple model combining the overdamped Brownian oscillators to describe the dynamic disorder originating from the environmental fluctuations and the transition charge from the electrostatic potential coupling model to determine the interactions between chromophores. We demonstrate that with this model, both the calculated spectra and the EET rates between the two rings within the LH2 complex agree well with experimental results. We further find that the transfer between the strongly coupled rings of neighboring LH2 complexes can also be well described with our method. We conclude that our new method accurately describes the EET rate for biologically relevant multichromophoric systems, which are similar to the LH2 complex. Computationally, the new method is very tractable, especially for slow processes. We foresee that the method can be applied to efficiently calculate transfer in artificial systems as well and may pave the way for calculating multidimensional spectra of extensive multichromophoric systems in the future. [ABSTRACT FROM AUTHOR]

The purpose of dissolved gas analysis (DGA) in utilities is to help detect the presence of abnormality within transformer. When faults occur in transformers, transformer engineers need to determine the location and risk of the faults. Ultimately, they have to decide, based on DGA, whether to continue operating or not, perform internal inspection, or dispose the transformer. In this study, the fault and failure types in the transformer are suggested to determine the location and risk of the faults. In particular, turn-to-turn insulation faults are classified as degradation and breakdown. These faults are difficult to identify during internal inspection, and have a high possibility of failure. Urgent decision and action are thus required to avoid failure. In degradation of turn-to-turn insulation faults, failures may occur by generating thermal gases in paper during a long period of time. In breakdown of turn-to-turn insulation faults, thermal gases are not generated in paper, and failures are rather due to sudden breakdown of insulation. This study also presents a typical example of a turn-to-turn insulation fault. This example shows the progress of the fault from thermal to discharge, which is common phenomena in winding fault. Based on the findings of this work, transformer engineers can determine by DGA if transformers can be operated with or without internal inspection, or disposed when the fault has not been identified during internal inspection. [ABSTRACT FROM AUTHOR]

An closed oil circulating system with plane electrode was built to study the effect of space charge on oil flow electrification under DC voltage. The results reveal that with the increase of applied voltage, the streaming current was always enhanced. However, the polarity of streaming current depends on the sample configuration. If the negative high voltage electrode was exposed to oil layer, streaming current was negative. Otherwise streaming current had a tendency to be positive as applied voltage increased. In experimental model without exposed electrode, the polarity of streaming current was always positive. And the amplitude of streaming current was related to the number of insulating papers placed under electrode. More craft papers placed under negative high voltage electrode led to the increase of streaming current. Based on the bipolar transport model, a new simulation method is proposed to study the effect of charge injection and transportation on flow electrification under DC voltage. The simulation results agree well with the experimental result. [ABSTRACT FROM AUTHOR]

DC railway electrification was deployed at the beginning of the 20th century in several countries in Europe. Today, this power system is no longer adapted to the demands of increased rail traffic. Due to the relatively low voltage level, the current consumed by the trains reaches several kAs. So, in the worst case, the locomotives cannot operate at their rated power due to the voltage drop along the contact line. Conventional solutions to reduce the voltage drop consist of increasing the cross-section of overhead lines or reducing the length of sectors by installing additional substations. Nevertheless, these solutions are expensive and not always feasible. The implementation of a Modular Battery Energy Storage System (MBESS) can be an alternative solution to reinforce the railway power supply. This paper first presents an MBESS based on elementary blocks associating Full-SiC Isolated DC-DC converter and battery racks. The electrical models of a railway sector and an elementary block are described, and simulations are performed considering real railroad traffic on two sectors of the French National Rail Network, electrified at 1.5 kV. The results show that the installation of an MBESS in the railway sector boosts the locomotive's voltage while also increasing overall system efficiency. [ABSTRACT FROM AUTHOR]

The inherent second harmonic power pulse in single-phase grid-connected rectifiers leads to a noticeable output voltage ripple and thus results in the degradation of the system. A novel second harmonic suppression control is introduced in this paper to address this issue. The key point of the proposed control lies in the real-time prediction of the phase-shifted full-bridge (PSFB) converter's desired duty cycle through accurate PSFB converter modeling. By accurately predicting the ideal duty cycle, the proposed control facilitates a significant enhancement in the control loop's gain specifically at the second harmonic frequency, thereby improving the overall system performance. To validate the theoretical analysis, a series of simulations and experiments were conducted. The results demonstrate the effectiveness of the proposed second harmonic suppression control in mitigating second harmonic output voltage ripple. [ABSTRACT FROM AUTHOR]

High frequency and high voltage switching converters utilizing wide bandgap semiconductors are gaining popularity thanks to their compactness and improved efficiency. However, the faster switching requirements gives rise to new challenges. A key issue is the increased oscillation of the drain–source voltage caused by the switching action of the complementary switch in the same phase or change of state of the other phase switches. The voltage stress caused by these oscillations can damage the switch. Furthermore, the high dv/dt during turning-on of one switch might result in false turn-on of the complementary switch due to the miller effect. In this paper, these issues are investigated in a T-type converter through analytical and experimental analysis. Based on the proposed analytical approach, simple and cost-wise solutions utilizing an optimum design of gate driver circuits and circuit layout modifications can be developed to cope with the aforementioned issues. A comprehensive analytical model of the converter with consideration of parasitic capacitances and inductances is developed. By performing sensitivity analysis on the model, the effect of the parasitic parameters on the drain–source voltage oscillation and gate–source voltage amplitude in case of false turn-on is studied. The validity of the model is then assessed through numerical simulations and experimental results. [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]

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 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]

The zero-relaxation limit of Euler–Poisson systems for ion dynamics in a slow time scale leads to drift-diffusion equations. This fact was justified in previous works. This paper concerns global error estimates between solutions of Euler–Poisson systems and that of drift-diffusion equations. In the proof, we use Sobolev inequalities and employ a multiplier related to the electric potential. [ABSTRACT FROM AUTHOR]

The traditional medium-voltage distribution network fault location method uses mainly the voltage and current measurements of the medium-voltage side, which results in problems such as high installation costs at the measuring points and complicated postoperation and maintenance work. Therefore, a fault location idea based on the distributed measurement of low-voltage side voltage is proposed in this paper. First, the characteristic voltage is adaptively selected according to the fault type. Second, the suspected fault section is determined by comparing the characteristic voltage amplitude of each measuring point. Third, the fault section is located using the section unit characteristic voltage drop defined for each suspected fault section. Finally, fault distance estimation is achieved based on the voltage difference matrix and characteristic voltage analysis. This method achieves accurate fault distance identification based on the distribution difference of the characteristic voltage of the low-voltage side under the fault state. This work provides a new economical and practical idea for determining the fault locations of distribution networks. The effectiveness of this method is evaluated by considering a 10 kV distribution network in Guangdong Province built in PSCAD/EMTDC. [ABSTRACT FROM AUTHOR]

As the information technology (IT) industry advances, embedded systems are being applied in various industrial sectors. With the expansion of application areas, there is a growing demand for high-precision, high-specification embedded systems, leading to the increased complexity of embedded software. Consequently, software errors can cause system malfunctions, resulting in accidents such as airplane crashes and the sudden acceleration of cars, leading to significant loss of life and property damage. Therefore, measures to ensure the safety and stability of increasing embedded systems malfunctions are necessary. This paper proposes a system that monitors the operation of target embedded systems in real-time and compares the extracted normal operation current/voltage patterns with the current/voltage data of a target embedded system (TES). It compares the operation data of the TES with automatically generated normal operation patterns by forcibly exposing them. It suggests algorithms for immediately detecting and efficiently recovering from the TES malfunctions. The proposed system applies two algorithms. (a) Monitoring TES current: When a malfunction is detected, a monitoring embedded systme (MES) resets the TES to restore normal operation. If malfunctions persist, it controls TES by using an algorithm to shut it down. Additionally, a proportional integral derivation (PID) control is applied to stabilize the current state. (b) Monitoring TES voltage: If a voltage drop occurs, the MES immediately stops the TES operation to minimize damage. The proposed algorithms were validated through experiments. For a normal TES consuming up to 95 mA, an error detection rate of 20% was applied. The TES was reset if it consumed over 114 mA. It was confirmed that the TES was stopped upon detecting the third malfunction. Regarding voltage, when the normal operating voltage of the system was around 5 V, if the TES operating voltage dropped below 4.3 V, it was detected as a malfunction, and the algorithm to stop the TES operation was validated. [ABSTRACT FROM AUTHOR]

As the electricity market expands with increasing demand, power systems are under more pressure to operate within secure limits. One way to ensure this is through load flow studies, which analyze the steady-state conditions of a power system under various load and generator scenarios. However, the complexity of power systems and the growing demand for electricity make it difficult to accurately predict and analyze power flow. The use of simulation software like electrical transient and analysis program (ETAP) can improve the accuracy and efficiency of load flow studies, but it still poses challenges such as complexity and lack of standardization in use. This paper focuses on voltage stability, voltage regulation, and the impact of capacitor banks on buses through load flow studies. Real data from four hydropower plants is used to analyze voltage drop, voltage regulation and power losses at each bus. The findings highlight the effectiveness of capacitor banks in improving voltage profiles and reducing power losses, thus proposing an optimized system design. These enhancements facilitate better planning, operation, and expansion of power systems, ensuring more reliable and efficient electricity supply. [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]

This paper deals with the control and performance improvement of parallel-operated voltage-source inverters (VSIs) controlled as virtual synchronous generators (VSGs). In publications regarding the parallel-operated VSGs, transmission lines are considered to be mainly inductive. However, less analytical works have been done regarding the control of paralleled VSGs in low-voltage grids with dominant resistive impedances. Once VSIs are controlled as VSGs in a microgrid with more resistive transmission lines, swing equation and system representation for the power-angle synchronization will change leading to a new control structure. Therefore, this paper deals with the control of parallel-operated converter-based VSGs in low-voltage grids with dominant resistive line impedances. In this way, the VSG representation, comprising the swing equation and V-P droop characteristic, for applications in highly resistive microgrids is presented, in which the swing equation and VSG frequency are related to reactive power. Then, the V-P droop characteristic is modified and an enhanced P-V droop characteristic for proper sharing of active power between the VSGs in highly resistive microgrids is proposed. Next, the VSG control is modified so that the R/X ratio at the VSG output increases and thus the decoupled control of active/reactive powers in relatively inductive cases is realized as well. [ABSTRACT FROM AUTHOR]

This paper presents application and tuning of the equilibrated residual method (ERM) of a posteriori error estimation for coupled electromechanical problems of direct, inverse and general piezoelectricity. In these three cases, either electric potential is induced by strains or strains appear due to the applied electric potential or both phenomena occur simultaneously. The mentioned ERM is assigned for the assessment of modeling and approximation errors of the numerical finite element solution. Such error values usually serve as indication for adaptive hierarchical modeling and adaptive mesh changes within thin and/or solid piezoelectric members so as to obtain the solution of assumed accuracy. [ABSTRACT FROM AUTHOR]

In this paper, a new GaSe/ZnS van der Waals heterostructure (vdWH) is devised and subjected to systematic analysis through first principles calculations in terms of its geometric, electronic and transport properties. The stability of GaSe/ZnS vdWH is verified through binding energy, phonon spectrum, and ab initio molecular dynamics (AIMD) simulation. Additionally, detailed calculations of plane average electron density difference and average electrostatic potential in the features of GaSe/ZnS vdWH interface are provided. The results show that GaSe/ ZnS vdWH comprises a heterostructure with a direct band gap of 2.19 eV and high carrier mobility. Among them, the electron mobility along the x direction reaches 1 394.63 cm²V-1⋅s-1, while the electron mobility along the y direction reaches 1 913.18 cm² ⋅V-1 ⋅s-1, demonstrating excellent performance and potential applications in electronic nano devices. [ABSTRACT FROM AUTHOR]

Solar photovoltaics in Malta have increased substantially over the years, both at large scale and residential scale. The present installed capacity is already having a negative impact on Malta's' grid infrastructure, causing problems due to the reverse power flows (resulting from oversupply) and related issues such as voltage rise. This paper considers the integration of a low voltage regulator in a low voltage feeder in a semi‐rural area in Malta. A thyristor‐controlled transformer‐based low voltage regulator was modelled and simulated in MATLAB/Simulink using the PLECS blockset. Experimental results were also obtained via measurements of the voltage profiles at 70% of the actual low voltage feeder that showed several instances of over and under voltage events. The outputs obtained from the simulation model strongly agreed with those obtained from the field testing thereby validating the simulation models that were developed in this study. Results show that the voltage on the feeder was successfully regulated to around the nominal voltage of 240 V. The regulator failed to correct the voltage to within ±10% in one occurrence where the load demand and hence the voltage drop was too high. [ABSTRACT FROM AUTHOR]

2-(3-Bromophenyl)-1-(4-morpholinyl)ethanone belongs to one of morpholine derivatives. In this paper, 2-(3-bromophenyl)-1-(4-morpholinyl)ethanone was synthesized by a two-step synthesis method. In order to determine the structure of the target compound, FT-IR,1H NMR,13C NMR and MS were used for detection. Meanwhile, X-ray diffraction was used to detect the single crystal and obtain the crystal structure data of the target compound. The molecular crystal structure was compared with that determined by density functional theory. The frontier molecular orbitals and molecular electrostatic potential energy were used to further study the physical properties of the compounds. [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]

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]

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]

In this paper, the governing equation of a piezoelectric semiconductor (PSC) is derived after a consideration of flexoelectricity and the strain gradient effect. A one-dimensional first-order beam model is obtained through integration across its section. Based on this model, theoretical analysis is carried out for a cantilever PSC nanowire subjected to a time-harmonic transverse shear force. The effects of flexoelectricity and the strain gradient on bending vibration characteristics are investigated, including the natural frequencies and distributions of physical quantities. The results show that the strain gradient effect on the natural frequency and stiffness of a PSC nanowire is greater than that of flexoelectricity, while with regard to the influence on electric potential and carrier concentration, the reverse is true. Our findings shed light on the design and optimization of PSC devices such as energy harvesters at the nanoscale. [ABSTRACT FROM AUTHOR]

Regarding the advances in technology and anxieties around high and growing prices of fossil fuels, government incentives increase to produce cleaner and sustainable energy through distributed generations. This makes trends in the using microgrids which consist of electric demands and different distributed generations and energy storage systems. The optimum operation of microgrids with considering demand-side management increases efficiency and reliability and maximize the advantages of using distributed generations. In this paper, the optimal operation scheduling and unit commitment of generation units installed in a microgrid are investigated. The microgrid consists of technologies based on natural gas that are microturbine and phosphoric acid fuel cell and technologies based on renewable energy, including wind turbine and photovoltaic unit along with battery energy storage system and plug-in electric vehicle commercial parking lot. The goal of the paper is to solve a multi-objective problem of maximizing revenues of microgrid operator and minimizing emissions. This paper uses an augmented epsilon constraint method for solving the multi-objective problem in a stochastic framework and also implements a fuzzy-based decision-maker for choosing the suitable optimal solution amid Pareto front solutions. This new model implements the three type of the price-based and incentive-based demand response program. It also considers the generation reserve in order to enhance the flexibility of operations. The presented model is tested on a microgrid and the results demonstrate the efficacy of the proposed model economically and environmentally compared to other methods. [ABSTRACT FROM AUTHOR]

A kind of material, microencapsulated electronic ink, was prepared and supported on ITO glass used as backplane electrode and etched panels of the words "N-P-U" as pixel electrode. In addition, a quasi-dynamic display device was designed for electronic paper. The control signal generated by monostable process of 555 counter was used to drive the relay to work. The actual output of this kind of display was also observed. Through the combination of 555 counter and relay, quasi-dynamic electronic ink display was able to be achieved at the voltage of 15V. Furthermore, the delay time can be controlled within 0-10 seconds by adjusting monostable trigger time of the counter. [ABSTRACT FROM AUTHOR]

In this paper, a new hybrid stator fabrication with 2-D steel sheets lamination and 3-D end cap structure for high-speed motor application is provided. With the additional overhead end cap design, the new motor not only features lower iron losses in high frequency and reduces copper losses like traditional soft magnetic composite (SMC) motor but also achieves higher permeability and lower production cost at the same time. In this paper, the motor characteristics, i.e., back electromotive force and efficiency between the traditional lamination, SMC, and the new hybrid design are investigated by 3-D FEA simulation. Moreover, a prototype is fabricated by 3-D printing for the verification of the analytical and simulation results. [ABSTRACT FROM AUTHOR]

Dynamic response of molecular reorientation near the alignment surface of bistable cholesteric liquid crystal devices was observed by means of the total reflection ellipsometry. From the experimental results, the deviation from the original switching voltage to which the image sticking problem has a close relationship was confirmed, and the cause of the image sticking problem was considered from the viewpoint of the surface energy and Helfrich-type modulation. Especially when the surface free energy is low, director near the alignment surface seems to be distorted by disclinations and Helfrich-type modulation. [ABSTRACT FROM AUTHOR]

The introduction of an equivalent model for a regional power area in a large-scale power system with complex loads is essential for reducing the computation burden in real-time dynamic analyses. In this paper, we propose a generalized discrete-time equivalent model (GDEM) with specific relations among model parameters for simulating the physical characteristics of a regional power area. The GDEM facilitates the interconnection of equivalent models representing regional power areas and improving the simulation accuracy and speed in large-scale dynamic power systems. This paper first investigates the inherent relations among GDEM parameters in the discrete-time models of synchronous generators and composite loads so as to guide the GDEM parameter estimation in regional power areas. This paper then develops relations among GDEM parameters for a regional power area. Numerical experiments are conducted by simulating ground faults in the China Electric Power Research Institute system and the accuracy of the proposed GDEM is verified by analyzing the dynamic simulation results. In addition, this paper has applied the GDEM to study the regional power area of Central China, which validates the use of GDEM in practical power system analyses. [ABSTRACT FROM AUTHOR]

A new modular pulsed-power source with fast rise time and step-wise arbitrary output waveform generation is currently under development to drive the Gepulste Elektronenstrahlanlage device investigated at the Institute for Pulsed Power and Microwave Technology (IHM). Acknowledging the complex design procedures necessary to set up a modular pulsed-power source for voltages of up to 120 kV, this paper focuses on the circuit design for a single stage and its validation prior to the generator assembly. Using a semiconductor-based Marx generator topology, the stages are designed to have an output voltage of 1 kV with a pulse current of up to 600 A. When connected to an ohmic load, the measured current rise times are in the order of 46 ns resulting in the current rise rates of up to 10 kA/ $\mu \text{s}$ using the commercial devices. The step-wise arbitrary output waveform is created by generating the switching commands on the stage using a microprocessor and a fast optical synchronization unit. Effective stage shielding is verified by operating the stage in a 100-kV, 2.5-kA electromagnetic interference test bed. This paper presents the design considerations and the corresponding measurements. [ABSTRACT FROM AUTHOR]

This paper presents a new conformal mapping method to solve 2D Laplace and Poisson equations in MOS devices. More specifically, it consists of an analytical solution of the 2D Laplace equation in a rectangular domain with Dirichlet boundary conditions, with arbitrary values on the boundaries. The advantages of the new method are that all four edges of the rectangle are taken into account and the solution consists of closed-form analytical expressions, which make it fast and suitable for compact modeling. The new model was validated against other similar methods. It was found that the new model is much faster, easier to implement, and avoids many numerical issues, especially near the boundaries, at the cost of a very small loss in accuracy. [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]

This paper proposes a new full‐order adaptive observer algorithm to overcome the instability of speed sensorless vector control system of induction motor at low speed, especially at extremely low speed. The algorithm consists of the improved feedback matrix algorithm and the improved speed adaptive law algorithm. By establishing an observer state error equation considering the non‐linear voltage error of the inverter and the stator resistance voltage drop, a feedback matrix was designed to reduce the effect of inverter's non‐linear voltage error and stator resistance voltage drop on speed estimation. Meanwhile, this paper improves the traditional adaptive law. The basic idea is to add compensation amount equivalent to the non‐linear voltage error, and the compensation amount is adaptive to the running speed and load to improve the motor speed estimation accuracy at low speed. Extensive experimental tests have been carried out to evaluate the performance of the proposed algorithm using a 2.2 kW induction motor experimental platform. The experimental results show that the algorithm presented in this paper can guarantee the stable operation of the motor under the rated‐load and 180% rated‐load at low, extremely low and 0 speed with good dynamic and static characteristics. [ABSTRACT FROM AUTHOR]

In life as well as in engineering, many times, it is necessary to choose the best option among many different options. That will be more difficult when the criteria given for the selection contradict each other. For example, when external cylindrical grinding, the minimum surface roughness requirement necessitates a small depth of cut and feed rate. The material removal rate will be reduced in this case, and this requirement will conflict with the maximum material removal rate requirement. To solve the above problem, a very useful tool is multi-criteria decision-making (MCDM). In this paper, for the first time, MCDM results for powder mixed discharge machining (PMEDM) cylindrical parts of SKD11 tool steel with copper electrodes have been presented. In this work, eighteen experiments with the L18 (16×53) design using the Taguchi method were conducted. Six main input process parameters include the powder concentration, the pulse current, the servo voltage, the pulse on time, and the pulse off time. To select an alternative that simultaneously ensures two criteria including minimum surface roughness (RS) and maximum material removal speed (MRS), four different MCDM methods including MAIRCA (Multi-Attributive Ideal-Real Comparative Analysis), MARCOS (Measurement of Alternatives and Ranking according to Compromise Solution), TOPSIS (Technique for order of preference by similarity to ideal solution), and EAMR (Area-based Method of Ranking) and two methods of criteria weight calculation including MEREC (Method based on the Removal Effects of Criteria) and Entropy methods were selected. The results of MCDM when PMEDM SKD11 tool steel cylindrical parts with two methods for weight determination and four methods for solving MCDM problem were evaluated. In addition, the best alternative to ensure simultaneous minimum RS and maximum MRS was proposed. [ABSTRACT FROM AUTHOR]

The method of symmetrical components is an important mathematical tool for electrical engineering, as it simplifies the analysis of unbalanced electrical circuits. The method is used almost exclusively for three-phase networks, but with the advancement of multiphase electrical systems, it could be convenient to utilize it for such systems as well. In this paper, the method of symmetrical components is used to analyze a generic five-phase electrical system for various short-circuit faults and to determine the sequence networks connections for these faults. The analysis performed covers the derivation of the symmetrical components for voltage/current and of fault currents. The analytical results and the inferred sequence networks connections are validated by computer simulations. This paper therefore extends the literature on short-circuit analysis of multiphase electrical systems using the method of symmetrical components. [ABSTRACT FROM AUTHOR]

Describes the above-named upcoming special issue or section. May include topics to be covered or calls for papers. [ABSTRACT FROM PUBLISHER]

In this work we describe the Square Wave Anodic Stripping Voltammetry (SWASV) electrochemical technique for the determination of lead (Pb2+) and cadmium (Cd2+) metal ions at concentration of sub-part per billion (ppb) in aqueous solution. Moreover, simple and low-cost procedures for the fabrication of high performance working nano-electrode are reported. The electrode structure consists of a graphene paper (GP) $240~\mu \text{m}$ thick with the function of electrical conductor and substrate, a layer of nafion 0.5- $0.7~\mu \text{m}$ thick onto the graphene paper and bismuth nanoparticles embedded in the nafion thin layer. The bismuth nanoparticles were fabricated by electrodeposition starting from Bi(III) ions, employing a key step of hydrogen ions of nafion $\text{H}^{\mathbf {+}}$ exchange with bismuth ions Bi(III). This procedure is aimed to improve the bismuth nanoparticles concentration. The SWASV applied to the low-cost nanoelectrode allows detecting Pb2+ and Cd2+ at concentration as low as 0.1 ppb. [ABSTRACT FROM AUTHOR]

When an alternating voltage is applied to a dielectric material, dipoles in the material try to align in the direction of the applied voltages and polarization process starts. For multi-dielectric media especially in which a liquid interface is involved, such as oilpaper insulation, interfacial polarization is predominantly active among all polarization processes. This interfacial polarization is a very slow process and is effective in lower frequency range. This interfacial polarization reflects the inherent condition of the oilpaper insulation. Due to this reason, frequency domain spectroscopy is performed in lower frequency range to assess the condition of oil-paper insulation. So, the time required for frequency response measurement using conventional frequency domain spectroscopy is quite long. Considering the aforesaid facts, a different procedure has been taken here to measure the dielectric response in a significantly lesser time keeping the entire frequency range of conventional frequency domain spectroscopy. Instead of using pure sinusoidal excitation voltages over wide frequency range, dielectric response current has been measured using excitation having time growing frequency sweep (TGFS) signal. For this purpose, test samples that emulate the oil-paper insulation of real-life transformer have been prepared in the laboratory. The moisture contents of the test samples have been kept different to investigate the reliability of the proposed method. A setup has been made in the laboratory to measure dielectric response currents using the both excitations. In order to investigate the applicability of the proposed method, experiment has also been performed on actual transformers. It has been observed that the use of excitation signal having time growing frequency sweep provides almost similar information regarding insulation condition as obtained by the use of conventional sinusoidal excitation voltages. Hence, the proposed method is capable of reduction in time in FDS nearly by an amount of 85%. [ABSTRACT FROM PUBLISHER]

The rapidly drop of frequency in the microgrid (MG) system when it operates under island operation has caused frequency stability problems. In case, generators and renewable energy sources cannot supply enough power to restore the frequency, the load shedding will be proceeded. This paper proposes the load shedding method based on the coordinate multiple load shedding factors when the MG system operates in island mode. This proposed method carries out an approach through two main steps. Firstly, the optimal amount of load shedding power considering renewable energy sources and the ability to adjust the primary and secondary frequencies of the generator is calculated to restore the frequency to the allowed range. Next, distributing the optimal load shedding power for each bus is based on the combination of different criteria to meet the economic and technical goals. On the technical side, this paper also considers two criteria about the voltage distance, and the voltage sensitivity index. These two criteria contribute to reducing voltage drop and improving voltage stability when the microgrid operates in island mode. From the economic perspective, it considers the load importance factor, thereby minimizing the economic losses caused by load shedding. The AHP algorithm is applied in this paper to determine the importance of loads and the importance of the different criteria when they are combined. The effectiveness of the proposed method is demonstrated through simulation of IEEE 16-bus microgrid with 6-source. [ABSTRACT FROM AUTHOR]