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In this work, Ti3C2/single-layer black phosphorus (BP)/Ti3C2 resistive random access memory (RRAM) was studied based on the first-principles theory. First, after determining the size of the material, the Ti3C2/BP(100) interface was built. By studying the electrostatic potential of the interface, it was found that there was a Schottky barrier at the interface, and the barrier height was obtained by calculating the work function and the band structure of the interface. Next, a Ti3C2/BP(100)/Ti3C2 RRAM device was designed based on the mechanism of the Schottky barrier at the interface. The bipolar switching characteristics were confirmed after calculating the I–V curve of the device, in which the turn-on threshold voltage is about 1.5 V, the turn-off threshold voltage is about 0.5 V, and the switch ratio is greater than 105. However, there are still shortcomings such as insufficient drive current. So, in the end, the optimization program is determined through a series of studies of device doping and vacancy, and it is found that after a certain concentration of Mg atoms are adsorbed, the conductivity of the resistive switching layer can be increased, the interface barrier can be adjusted, and the device performance such as the turn-on voltage, drive current, and switching ratio can be improved. This work may have guiding significance and value for the experimental research of manufacturing a new two-dimensional material RRAM. [ABSTRACT FROM AUTHOR]

An analytical model for transient stability assessment of hybrid AC–DC transmission systems is formulated, implemented, and validated. The equal‐area criterion, as known from the transient stability analysis of AC power systems, is redeveloped for AC–DC power systems using high‐voltage direct current (HVDC) transmission based on the voltage sourced converter and in particular the modular multilevel converter (MMC). Through the proposed analytical solution, the critical clearing angle and the critical clearing time are obtained through symbolic calculations for the most severe DC and AC short‐circuit faults. The assumptions made to enable the formulation of the analytical solution are conservative with respect to the assessment of transient stability. Since the analytical solution is a function of main system parameters and prefault active power flows, it offers an answer to an entire set of problems. It so yields a direct method of transient stability assessment that provides an in‐depth and educational insight into the parameters influencing transient stability. As an illustrative application, the impact of scheduled power flows on DC versus AC lines on the transient stability is analysed. In the performed validation involving the comparison with a computationally more expensive numerical solution, the assumptions underlying the analytic solution were justified. [ABSTRACT FROM AUTHOR]

Electrochemical chloride extraction (ECE) is an effective method to remove chloride ions in reinforced concrete. In addition, cracks in concrete have self‐healing properties. The self‐healing properties of concrete may affect the ECE process. Based on moving mesh technology, this paper simulates the ion migration process of ECE in crack‐self‐healing concrete. According to the simulation results, the distribution of ions in the reinforced concrete and the electric potential change law inside the concrete are analyzed during the ECE process. The effects of cracks or no cracks in the anode area of ECE, self‐healing or no self‐healing, and different self‐healing rates on the efficiency of ECE were discussed. This research will have a positive impact on ECE's research. [ABSTRACT FROM AUTHOR]

With the rapid development of microgrids, voltage drop has become one of the focuses on the research of microgrid stability and grid-connected operation. In this article, an improved fuzzy voltage compensation control strategy (FVCC) is proposed to solve the bus voltage drop problem. This method takes the influence of feeder impedance into account, and there is no need to accurately measure the feeder impedance value. Since droop control and feeder impedance can lead to voltage drop and bus voltage instability, fuzzy control is applied to compensate bus voltage. Specifically, aiming at the voltage drop caused by droop control, an adaptive fuzzy controller is designed to automatically find suitable gain parameters to reduce the voltage difference. In addition, bus voltage gain module is added to compensate the voltage consumed by feeder impedance. The compensation only needs to measure the voltage at both ends of the line, without testing the line parameters. Finally, the simulation results show that the control strategy achieves the expected effect. [ABSTRACT FROM AUTHOR]

The penetration level of photovoltaic (PV) keeps increasing in modern distribution networks, which leads to various severe voltage limits violation problems. This article aims to aggregate and utilize the PV inverters for voltage regulation by a fully distributed two-level Volt/VAr control (VVC) scheme. In the lower-level VVC (real-time scale), the rooftop PV inverters are aggregated via consensus algorithms and then governed by droop controllers in medium-voltage networks. The droop controller adjusts the reactive power output of each PV aggregator in real-time from its dispatched value depending on the bus voltage variations. In the upper-level VVC (15-min timescale), the reactive power of PV aggregators is dispatched for power loss minimization, where control signals are set as base values for PV aggregators. This problem is formulated as second-order cone programming and solved by the alternating direction method of multipliers. The simulation results demonstrate the effectiveness of the proposed method in both short-term and long-term scenarios with different system scales. [ABSTRACT FROM AUTHOR]

In this article, a fixed and smooth-switch-sequence modulation strategy is proposed to equalize the dc-link voltages among the cascaded rectifier. The structure of a single-phase three-level neutral-point-clamped cascaded rectifier is studied. Three core steps of this strategy are analyzed respectively, including carrier wave disposition calculation, fixed pulse generator, and voltage rank function. In addition, a criterion of the degree of the load unbalance is established in order to measure the voltage balancing boundary of the presented approach. The superiorities of the proposed control strategy embody the smooth switch sequence, the strong voltage balance capability, as well as the fixed switch sequence. Owe to these advantages, the cascaded rectifier could effectively reduce the switching frequency, achieve the goals of voltage balancing, and reduce the calculation burden of the controller when the number of cascaded modules is large. The effectiveness of the proposed strategy is verified by simulation and experiment results. [ABSTRACT FROM AUTHOR]

In this work, we propose a flexible ferroelectric tunnel junction (FTJ) with a nanometer-thick single-crystalline BaTiO3 barrier prepared by exfoliating and transferring epitaxial BaTiO3 thin films onto flexible poly(styrenesulfonate)-doped poly(3,4-ethylenedioxythiophene) (PEDOT:PSS) conductive electrodes using a water-soluble Sr3Al2O6 sacrificial layer. The transferred freestanding BaTiO3 films remain single crystalline and exhibit clear ferroelectric hysteresis, no matter being flat or bent. A combined piezoelectric force microscopy and conductive atomic force microscopy measurement reveals that the Pt/BaTiO3/PEDOT:PSS FTJ shows a clear polarization direction modulated tunneling resistance. By using x-ray photoelectron spectroscopy, the polarization direction-dependent electrostatic potential profile of this flexible FTJ has been reconstructed, consistent with the observed resistance modulation. [ABSTRACT FROM AUTHOR]

A liquid crystal (LC)-based double dipole terahertz phase shifter is proposed. The block model is utilized in simulations to analysis the influence of inhomogeneity of the LC substrate. The sensitive parameters of the double dipole are simulated and analyzed. An array consisting of 30 × 30 patch elements is designed and fabricated. Experimental results exhibit that the phase shift is over 360° in the range of 355.8–358.8 GHz at 1 kHz, at an applied AC bias in the 0–50 V range. The phase change at different frequencies of AC bias voltage is also investigated, and the effect of the frequency of AC bias voltage is expressed by the coefficient of the amplitude of the bias voltage. [ABSTRACT FROM AUTHOR]

A repetitive electron beam driver based on 6-stage Linear Transformer Driver (LTD) cavities is presented. Each cavity consists of two Blumlein pulse forming networks (BPFNs) sharing a laser trigger switch. Voltage adding is obtained by means of Linear Transformer (LT) technology. The LTD cavity consists of two BPFNs connected in parallel, an LT with a ratio of 1:1, and a laser-triggered spark switch. The energy efficiency of a single LTD was investigated. The results show that the energy efficiency of an L-type BPFN and an LT was 94.3% and 92.8%, respectively. An electron beam driver consisting of 6 such cavities was developed with an output voltage of 740 kV, a current of 12.3 kA, and a power of 9.1 GW. The repetition frequency operation results show that the electron beam driver can operate stably for 20 s at 25 Hz with a jitter of approximately 1.7 ns. [ABSTRACT FROM AUTHOR]

Power loss and voltage regulation are two fundamental and challenging issues in DC distributed generation system. In this paper, a multi-objective optimization problem is established to achieve trade-offs between reducing power loss and decreasing voltage deterioration by adjusting the weighting coefficients. This problem is proven to be a convex optimization under constant impedance load and constant current load. A distributed algorithm based on random coordinate descent method is developed to solve this problem without acquiring the information of line impedance. Thus, the optimal operating point of the system can be found automatically in real-time, and the deviation of optimal solution caused by the fluctuation of network parameters is avoided. In addition, the complexity of this algorithm is low and its computational requirement is reduced in practice. Finally, case studies are implemented to verify the effectiveness of the proposed algorithm under the scenarios of line parameter fluctuation, load variation, communication line failure, and plug-play capabilities. [ABSTRACT FROM AUTHOR]

Opsin‐based transmembrane voltage sensors (OTVSs) are increasingly important tools for neuroscience enabling neural function in complex brain circuits to be explored in live, behaving animals. However, the visible wavelengths required for fluorescence excitation of the current generation of OTVSs limit optogenetic imaging in the brain to depths of only a few mm due to the strong absorption and scattering of visible light by biological tissues. We report that substitution of the native A1 retinal chromophore of the widely used QuasAr1/2 OTVSs with the retinal analog MMAR containing a methylamino‐modified dimethylphenyl ring results in over a 100‐nm redshift of the maxima of the absorption and fluorescence emission bands to near 700 and 840 nm, respectively. FT‐Raman spectroscopy reveals that at pH 7 QuasAr1 with both the A1 and MMAR chromophores possess predominantly an all‐trans protonated Schiff base configuration with the MMAR chromophore exhibiting increased torsion of the polyene single‐/double‐bond system similar to the O‐intermediate of the BR photocycle. In contrast, the A1 and the MMAR chromophores of QuasAr2 exist partially in a 13‐cis PSB configuration. These results demonstrate that QuasArs containing the MMAR chromophore are attractive candidates for use as NIR‐OTVSs, especially for applications such as deep brain imaging. [ABSTRACT FROM AUTHOR]

Direct modulation principle is widely used in modular multilevel converters (MMCs) for its simplicity and natural stability. However, it results in strong active and reactive power coupling. This paper carefully analyzes and identifies four power coupling paths and two power influence factors with the direct modulation principle. Full power decoupling of the MMC can be realized by cutting off the derived coupling paths and compensating the influence factors. However, this will further deteriorate the already poor damping of the MMC and significantly increase dc-bus current fluctuations. To solve this problem, the sources resulting in poor damping are identified and then a new closed-loop dc-bus current controller is incorporated into the control system. Finally, the proposed power decoupling strategy with the newly designed current controller realizes completely decoupled power regulation, avoids overload operation, and obviously improves the dynamic performance of the MMC. Furthermore, it increases the stability of the MMC system under all possible operation conditions. The proposed control strategy is confirmed by experimental results. [ABSTRACT FROM AUTHOR]

This paper presents a uniform control strategy for the bidirectional ac/dc interlinking converter (BIC) in hierarchical controlled hybrid microgrid. The uniform control strategy unifies different control structures for multifunctional BIC in terms of power management, ac and dc voltage support. With the unified control structure, various triggering mechanisms for BIC mode-switch are not compulsory in response to the relevant scenario changes in the power network. Therefore, the negative consequences, such as unsmooth transition and system collapse due to the inaccurate or slower mode switch, can be avoided. Moreover, the uniform control strategy is also applicable for the hierarchical controlled hybrid microgrid, whose control architecture is typically comprised of the centralized and decentralized levels. This enables the communication fault ride-through capability and the impact from the communication failures can thus be mitigated. To sum up the above two features, the proposed control strategy is able to provide a smooth operation for the BIC without control mode switch in the event of unintentional scenario changes in power or communication network. To verify the validity of the proposed uniform control strategy, the controller hardware-in-the-loop experimental results have been provided in this paper. [ABSTRACT FROM PUBLISHER]

Abstract: Layered O3‐type sodium oxides (NaMO2, M=transition metal) commonly exhibit an O3–P3 phase transition, which occurs at a low redox voltage of about 3 V (vs. Na+/Na) during sodium extraction and insertion, with the result that almost 50 % of their total capacity lies at this low voltage region, and they possess insufficient energy density as cathode materials for sodium‐ion batteries (NIBs). Therefore, development of high‐voltage O3‐type cathodes remains challenging because it is difficult to raise the phase‐transition voltage by reasonable structure modulation. A new example of O3‐type sodium insertion materials is presented for use in NIBs. The designed O3‐type Na0.7Ni0.35Sn0.65O2 material displays a highest redox potential of 3.7 V (vs. Na+/Na) among the reported O3‐type materials based on the Ni2+/Ni3+ couple, by virtue of its increased Ni−O bond ionicity through reduced orbital overlap between transition metals and oxygen within the MO2 slabs. This study provides an orbital‐level understanding of the operating potentials of the nominal redox couples for O3‐NaMO2 cathodes. The strategy described could be used to tailor electrodes for improved performance. [ABSTRACT FROM AUTHOR]

Li-rich layered material Li 1.1 Ni 0.35 Mn 0.65 O 2 was synthesized by a two-step calcination method, the relationship between the calcination conditions and the cyclic performance was studied. The results show the calcination conditions of the second step exhibiting great influences on the cyclic performance of the material. As the calcination temperature increases from 970 °C to 1030 °C, the discharge capacity of the prepared material increases firstly and then decreases, so does the discharge voltage fading. The material obtained at the temperature (The second step calcination) of 990 °C exhibits the highest discharge capacity and the highest discharge voltage fading. The material with longer second calcination time shows lower stable discharge capacity but smaller discharge voltage fading. The variation of the cyclic performance with the calcination conditions should be ascribed to the structural change, the electrochemical active area change and the electrochemical impedance. [ABSTRACT FROM AUTHOR]

This study proposes an advanced current control strategy for three-phase grid-connected inverters to reject the impact of the dc offsets and scaling errors in the grid voltage measurement on the grid current performance. The proposed current controller designed in the synchronous (d-q) reference frame is developed with a proportional integral (PI) plus three vector PI controllers. The PI controller regulates the fundamental current to follow its reference, meanwhile, three vector PI controllers tuned at the fundamental grid frequency ( \omega _s), 2\omega _s, 6\omega _s are employed to eliminate the dc, unbalance, harmonic components in the grid current. As a result, the three-phase grid currents are controlled to be balanced, sinusoidal, and extremely low dc component despite the presence of the dc offset and scaling errors in the grid voltage measurement and distorted grid voltage conditions. The main advantage of the proposed control scheme is that it is developed without the need of additional hardware circuit, dc extraction, and harmonic detection scheme so that it can be integrated into the existing grid-connected inverter system without extra cost. The effectiveness of the suggested solution is verified by experimental results under various grid voltage conditions and the grid voltage measurement errors. [ABSTRACT FROM PUBLISHER]

This article presents the voltage-dependent elastic properties of the novel piezoelectric composite metamaterials (PCMs). The angular rib of PCM consists of the bimaterial beam. Therefore, the deformation of bimaterial beam controlled by the applied voltage and stress affects the behavior of the PCM. It is possible to actively modulate the strain and Young's modulus by adjusting voltage. The effects of re-entrant angle and thickness of piezoelectric beam on their elastic properties are characterized. Considering the bending deformation of bimaterial beam based on the unit cell, the expression of voltage-dependent strain and equivalent Young's modulus are derived. A simplified model based on Euler-Bernoulli beam theory leading to the expression is derived for PCM. The finite element analysis of the mentioned structures is developed. And the correctness and validity of the closed-form analytical expressions in this paper are verified by comparing the numerical results with the analytical results. The results show that voltage-dependent Young's modulus of the PCM can be adjusted in a certain range by applying external voltage. And different elastic properties of the PCM can be shown in various combinations of re-entrant angle and thickness of piezoelectric beam. [ABSTRACT FROM AUTHOR]

Transient electromagnetic scattering by composite structures is formulated by time-domain combined field integral equations (TDCFIEs). Traditionally, the TDCFIEs are solved by combining the method of moments (MoMs) in space domain and march-on-intime (MoT) scheme in time domain. The space-domain MoM requires two basic functions to represent the electric and magnetic current densities on material interfaces, respectively, and the conventional choice of \hat n\times \mathrm RWG basis function for representing the magnetic current density may not be good in the TDCFIEs. In addition, the MoT scheme has a well-known late-time instability problem, which will aggravate in the surface integral equations with penetrable media. In this communication, the TDCFIEs for composite structures are solved by a different approach in which the Nyström method is used to discretize the space domain, while the Galerkin method with Laguerre basis and testing functions is employed to discretize the time domain. The proposed approach can fully overcome the drawbacks of the traditional approach as demonstrated by numerical examples. [ABSTRACT FROM AUTHOR]

This paper reviews results of partial discharge measurements and accelerated life tests performed on models of random and form wound insulation systems subjected to impulse voltage waveforms. The goal is to highlight how the features of the supply voltage affect the partial discharge activity and how this, eventually, reflects on the endurance of the insulation system. The most salient results are that, for both types of insulation systems, short rise times trigger PD of large magnitude, which are able to erode the insulation system faster than the partial discharges incepted using waveforms with longer rise times. In particular, failure times estimated by tests under sinusoidal voltages can be overly optimistic in assessing the long-term behavior of the insulation system subjected to impulse voltage waveforms. Frequency also is very important, as it controls the interplay between physical and chemical degradation rates. As a result, above partial discharge inception voltage the frequency acceleration rule does not hold, and can lead therefore to excessively optimistic results. [ABSTRACT FROM AUTHOR]

Multiple-voltage-region control, in which the bus-voltage range is divided into several regions, is usually implemented for dc microgrid operation in distributed manner. Voltage/power droop relationships are imposed for active power sharing among slack terminals. Conventionally, threshold voltages for voltage region partition are determined with fixed percentage of variation around the nominal value, which may result in unevenness of droop coefficients in different regions. If system droop coefficient is too high, significant bus-voltage step change due to load variation will occur. On the other hand, significant power sharing error among slack terminals will be induced if the droop coefficient is too low. In this paper, a compromised solution with power-capacity-based bus-voltage region partition is proposed to equalize the droop coefficients in different regions. However, the droop coefficients are determined based on the rated power capacity of system units. Bus-voltage discontinuity appears when the power capacity reduces in actual implementation. To eliminate the voltage discontinuity, online droop coefficient tuning according to the real-time power capacity is implemented. Algorithms for local power capacity estimation of solar photovoltaic (PV) and battery energy storage have been proposed. A lab-scale dc microgrid has been developed for verification of the proposed methods. [ABSTRACT FROM AUTHOR]

An N-type 50 V RF LDMOS with a RESURF (reduced surface field) structure of dual field plates (grounded shield, or G-shield) was investigated. The effect of the two field plates and N-drift region, including the junction depth and dopant concentration, on the DC characteristics was analyzed by employing the Taurus TCAD device simulator. A high BV (breakdown voltage) can be achieved while keeping a low RDSON (on-resistance). The simulation results show that the N-drift region dopant concentration has an obvious effect on the BV and RDSON and the junction depth affected these values less. There is an optimized length for the second field plate for a given dopant concentration of the N-drift region. Both factors should be optimized together to determine the best DC characteristics. Meanwhile, the effect of the first field plate on the BV and RDSON can be ignored. According to the simulation results, 50 V RF LDMOS with an optimized RESURF structure of a double G-shield was fabricated using 0.35 µm technologies. The measurement data show the same trend as the TCAD simulation, where a BV of 118 V and RDSON of 26 ohm·mm were achieved. [ABSTRACT FROM AUTHOR]

To address the reliability of rotating machine insulation, the International Electrotechnical Commission implemented new standards and technical specifications that are relevant to low-voltage and medium-voltage inverter-fed motors. Insulation evaluation under such power supply relies upon partial discharge (PD) measurements and accelerated life tests, which should be conducted (at least for the turn-to-turn insulation) under impulsive voltage waveform. The effect of impulsive voltage parameters on PD inception voltage and, in particular, endurance tests must be investigated to design test procedures that can indicate insulation quality and its behavior in service. This paper examines the effect of repetitive impulsive voltage waveform parameters on PD and the endurance (life) of organic insulation for rotating machine wires based on experiments performed on single-contact crossed pairs. Results show that the features of repetitive voltage impulse affect PD time and frequency characteristics, PD phase distribution, and endurance. Consequently, evaluation of insulation subjected to power electronics waveforms should take into account the appropriate choice of impulsive voltage parameter to fit to the type of PD phenomenology occurring in service conditions. [ABSTRACT FROM PUBLISHER]

The dependence of endurance test results on repetitive square wave voltage waveform parameters is investigated in this paper focusing on crossed pair specimens made of polyamide-imide enameled wires. Endurance tests carried out on crossed pairs above partial discharge inception voltage using both sinusoidal and square wave voltages show that lifetimes can be influenced significantly by voltage waveform parameters (rise time and frequency). Partial discharge statistics, recorded from test beginning to breakdown, are used to explain the remarkable differences associated with voltage waveform parameters. According to this study, the influence of voltage waveform parameters should be carefully considered in order to obtain effective evaluation of inverter-fed motor insulation systems. [ABSTRACT FROM AUTHOR]

Aims: Increasing evidence indicates that plant responses to ions (uptake/transport, inhibition, and alleviation of inhibition) are dependent upon ion activities at the outer surface of root-cell plasma membranes (PMs) rather than activities in the bulk-phase rooting medium. Methods: A web-accessible computer program was written to calculate the electrical potential ( ψ) at the outer surface of root-cell PMs ( ψ). From these values of ψ, activities of ion I with charge Z ({ I}) can be calculated for the outer surface of the PM ({ I}). In addition, ψ and { I} in the Donnan phase of the cell walls ( ψ and { I}) can be calculated. Results: By reanalysing published data, we illustrate how this computer program can assist in the investigation of plant-ion interactions. For example, we demonstrate that in saline solutions, both Ca deficiency and Na uptake are more closely related to {Ca} and {Na} than to {Ca} and {Na} (activities in the bulk-phase media). Additional examples are given for Zn and P nutrition, Ni toxicity, and arsenate uptake. Conclusions: The computer program presented here should assist others to develop an electrostatic view of plant-ion interactions and to re-evaluate some commonly-held views regarding mechanisms of ion transport, toxicity, competition among ions, and other phenomena. [ABSTRACT FROM AUTHOR]

Indirect matrix converter (IMC) is an alternative for ac/ac energy conversion, usually operated with a voltage stepped-down gain of only 0.866. For applications like distribution generation where voltage-boost functionality is required, the traditional style of operating the IMC is therefore not appropriate. Like most power converters, the operation of the IMC can surely be reversed to produce a boosted gain, but so far its relevant control principles have not been discussed. These challenges are now addressed in this paper with distributed generation suggested as a potential application. Simulation and experimental results for validating various performance aspects of the proposed control schemes can be found in a later section of this paper. [ABSTRACT FROM AUTHOR]

This paper focuses on the influence of repetitive square wave voltage rise time on partial discharge pulse characteristics in the ultra-high frequency range. Paerial Discharge (PD) tests on single-point contact crossed pairs were carried out using repetitive square wave voltages with a wide range of rise times, from 200 ns to 400 μs, including also 50 Hz sinusoidal voltage waveforms. Experimental results show that rise time has a significant influence on magnitude and frequency spectrum of PD pulses. Voltages of shorter rise times generate larger PD pulses with a predominance of high frequency components in the energy spectrum. Interpretations are presented for this phenomenon. [ABSTRACT FROM AUTHOR]

A novel one transistor and one diode (1T-1D) dynamic random access memory cell for embedded applications is proposed. This memory cell consists of a floating-gate (FG) MOSFET and a gated diode. The anode of the diode is connected to the FG, so that the threshold voltage of the FG MOSFET can be modulated by the current through the diode. In this paper, basic device operations, speed, retention, and disturb performance are investigated using Silvaco technology computer-aided design simulation tools. The process compatibility is also investigated by integrating the memory array and specific sense amplifier. [ABSTRACT FROM PUBLISHER]

Abstract: The novel diamond-wire sawing technology has been applied in the wafering of Czochralski (CZ) silicon. It is found that phase transformations take place on the wafer surfaces, associated with a smaller roughness. The wafers sliced by the diamond-wire saw have a greater mechanical strength than those by the conventional cutting process, beneficial for the preparation of thin wafers. With the decrease of silicon wafers, both the transmittance and the reflectance of sunlight increase in the long wavelength range. After fabricated into the solar cells by a standard process, their performances have been investigated. The short-circuit current significantly decreases with the wafer thickness, which is attributed to the reduction of effective light absorption. The open-circuit voltage also reduces to some extent since the surface recombination becomes more and more dominant in the minority carrier lifetime. For the ultrathin wafers with a thickness of 60μm, an average conversion efficiency of 16.8% can still be achieved for solar cells based on the standard fabrication process in photovoltaic industry. [Copyright &y& Elsevier]

For measuring currents flowing in three-phase rectangular-shaped busbars, in this paper, a planar coil with air core is used as a current sensing unit. The vector potential of the busbar and the electromotive forces of the planar coil for single- and three-phase currents are calculated with a numerical integration arithmetic. The relative error caused by adjacent busbars was simulated when the transducers were used for the three-phase current measurement. The simulation results show that the relative error induced by the adjacent busbars is less than 2%. Planar-coil-based current transducers enclosed with silicon rubber insulator are developed. The successful field trial of the transducers for more than four years shows that the transducers can meet the field requirement. [ABSTRACT FROM PUBLISHER]

In this paper, a modified one-cycle-control (OCC) scheme is proposed for regulating three-phase pulsewidth-modulated (PWM) rectifiers operating under unbalanced and distorted supply conditions. Mathematical analysis is first presented to show the dominant harmonic-voltage components appearing across the dc link of the PWM rectifier when it is controlled by an existing OCC scheme. Such dc-link harmonics when produced may aggravate harmonic currents flowing into the input terminals of the three-phase rectifier. To address these interrelated unbalance and harmonic concerns, the concept of reconstructing the appropriate reference signals in the OCC control core is introduced, before modifications are recommended for altering the key control equation. The improved OCC controller eventually developed is proven to exhibit minimal input-current distortion and a smoother dc-link voltage without using large capacitance. Other advantages exhibited by the traditional OCC scheme, such as no phase-locked loop, no frame transformation, and constant switching frequency, are also retained by the improved controller, whose theoretical findings are fully verified by experimental results obtained from a 1.2-kW three-phase PWM rectifier built in the laboratory. [ABSTRACT FROM PUBLISHER]

• PD detection using impulse voltage waveforms for electric vehicle motors insulation. • Impact of impulse voltage frequency on partial discharge inception voltage (PDIV) • Statistical analysis of PD signal on delay time and PD magnitude. • Influence of temperature on PD magnitude and delay time on Pharrell bar model. The urgent need for electric vehicles is the leading research to safer operation of electric motors on high frequency impulsive voltages. For low voltage electric vehicles partial discharge (PD) inception voltage tests under impulse voltage waveforms are desired. However, measuring PD using repetitive impulse waveforms is critical in selecting generators with appropriate parameters to increase PD detection sensitivity. Here, we report on PD characteristics for such kind of voltage waveforms, demonstrated with the high frequency and thermal impact on different types of motor insulation models. The increasing frequency of impulsive voltages tends to result in PD activities with low magnitude and short delay times. In this case, some PD pulses are missed because the PD and disturbance pulses produced by power electronic devices will likely overlap. Therefore, these parameters are carefully considered to evaluate the insulation performance of EV motors. [ABSTRACT FROM AUTHOR]

The Kerr effect in liquid of propylene carbonate near an insulator surface excited by pulsed high voltage was electro-optically measured with the data produced in the form of finite fringe interferograms. The fringe in the cathode region near the insulator surface was observed to shift inward, which implies a decrease of the cathode field near the insulator surface and somewhere near the cathode on the insulator surface being negatively charged. [ABSTRACT FROM PUBLISHER]

Intertied ac–ac microgrids offer many potential benefits like flexible frequency and voltage selection, reserve sharing and enhanced supply reliability. Operating them is however challenging due to their larger size and presence of more power converters with different responsibilities. These complexities can further be amplified when reliance on fast communication links is not permitted. To address these concerns, a new autonomous droop scheme is proposed here for managing intertied microgrids in either the islanded or grid-connected mode. The scheme prioritizes various power generation/transfer responsibilities among power converters found in the intertied microgrids. The objective is to smoothly maximize the overall power handling capability of the intertied microgrids without relying on fast communication links. The proposed scheme has been tested experimentally in the laboratory. [ABSTRACT FROM AUTHOR]

[Display omitted] • The solubility of 5-chloro-2-nitroaniline in twelve mono-solvent systems were measured. • The modified Apelblat, Margules, Wilson, NRTL and UNIQUAC models were employed to correlate the solubility. • HS and MEPS were used to determine the internal interactions within 5-chloro-2-nitroaniline solutions. • The mixing thermodynamic characteristics were derived by the NRTL model. The solubility of 5-chloro-2-nitroaniline in twelve mono-solvents (water, methanol, ethanol, n -propanol, isopropanol, n -butanol, isobutanol, acetone, 2-butanone, acetonitrile, methyl acetate, ethyl acetate) at 101.2 kPa (T = 283.15 ∼ 323.15 K) was investigated by experimental determination and molecular simulation. The static gravimetric tests showed that the solubility of 5-chloro-2-nitroaniline increased with the increase of absolute temperature, in the following order: 2-butanone > acetone > methyl acetate > ethyl acetate > acetonitrile > n -butanol > n -propanol > ethanol > isopropanol > isobutanol > methanol > water. The modified Apelblat, Wilson, NRTL, UNIQUAC and Margules models were used to correlate the experimental data, and the fitting results of the five models were satisfactory. By comparing the average ARD and RMSD values of the five models, the correlation results of the modified Apelblat model were the best. Hirshfrld surface analysis (HS) and molecular electrostatic potential surface (MEPS) were used to determine the internal interaction of 5-chloro-2-nitroaniline solution. The Hansen solubility parameters (HSPs) was utilized to assess the solvents' capability and to elucidate its ability to dissolve 5-chloro-2-nitroaniline. Furthermore, mixing thermodynamic characteristics of 5-chloro-2-nitroaniline in selected solvents were calculated by the NRTL model, which revealed that the mixing process was spontaneous and entropy-driven. These experimental results could be utilized for the purification, crystallization, and industrial applications of 5-chloro-2-nitroaniline as well as similar substances. [ABSTRACT FROM AUTHOR]

[Display omitted] • The solubility of N -acetyl- L -glutamine in twelve mono-solvent systems were measured. • The modified Apelblat model, Wilson model, NRTL model and UNIQUAC model were employed to correlate the solubility. • HS and MEPS were used to determine the internal interactions within N -acetyl- L -glutamine solutions. • The coverage Pearson correlation coefficients heatmap reflected the binary correlation between solubility and each parameter. • The mixing thermodynamic characteristics were derived by the NRTL model. In this work, the solid–liquid equilibrium solubility and solvent effects of N -acetyl- L -glutamine in twelve mono-solvent systems (water, methanol, ethanol, n -propanol, n -butanol, isobutanol, sec -butanol, acetonitrile, acetone, ethyl acetate, 2-butanone, methyl acetate) were reported at the pressure of 101.2 kPa (at T = 283.15–––323.15 K). Among the twelve mono-solvents, the solubility increased with the increase of absolute temperature, the order is: water > methanol > ethanol > sec -butanol > n -propanol > 2-butanone > isobutanol > acetone > methyl acetate > ethyl acetate > n -butanol > acetonitrile. The modified Apelblat model, Wilson model, NRTL model and UNIQUAC model were employed to correlate the experimental solubility, and the fitting results of the four models were all satisfactory. In addition, through comparison of the average ARD and RMSD values of the four models, the modified Apelblat model achieved the best correlation result. Hirshfeld surface analysis (HS) and molecular electrostatic potential surface (MEPS) were used to determine the internal interactions within N -acetyl- L -glutamine solutions. The Hansen solubility parameters (HSPs) and the coverage Pearson correlation coefficients (PCC) heatmap were utilized to assess the solvents' capability and to elucidate its ability to dissolve N -acetyl- L -glutamine. Furthermore, mixing thermodynamic characteristics of N -acetyl- L -glutamine in selected solvents were calculated by the NRTL model, which revealed that the mixing process was spontaneous and entropy-driven. These experimental results could be utilized for the purification, crystallization, and industrial applications of N -acetyl- L -glutamine as well as similar substances. [ABSTRACT FROM AUTHOR]

To improve the fault ride-through capability and power quality of a hybrid microgrid (HMG), a series compensation link (SCL) is inserted between an AC–DC HMG and a utility grid, which forms a new HMG topology. Correspondingly, a decoupling coordinated control strategy for the SCL and a bidirectional AC–DC interlinking converter (BIC) is proposed based on a small signal model of the entire system and the principle of voltage regulation. The interferences between the SCL and the BIC due to the coupling of control factors are eliminated by the series and parallel decoupling methods that adopt additional current closed-loop control and output voltage feedforward control, respectively. The proposed HMG topology and strategy can ensure the realization of the predesigned functions of dual converters and avoid frequent switching between the grid-tied mode and the island mode, which improves the fault ride-through capability and power quality. Finally, the effectiveness of the proposed approach is verified by simulations and experiments. [ABSTRACT FROM AUTHOR]

Penetration of wind and solar power are increasing in power systems. Intermittent characteristics of renewable sources and random load variation result in system voltage and frequency fluctuation. A load frequency control (LFC) strategy based on sliding mode control (SMC) theory and disturbance observer is proposed for the single area power system. In order to reduce the frequency deviation caused by the unmatched parameter uncertainties such as the renewable source and different load disturbance, the sliding mode load frequency controller is constructed by selecting the appropriate proportional and integral switching surface and the reaching law condition. Furthermore, the sliding mode load frequency controller is reconstructed based on the designed disturbance observer (DOB) to improve the dynamic performance and suppress the chattering. The proposed method is compared with the conventional sliding mode LFC and the robust adaptive LFC (RALFC) by using the matlab software, the simulation results show that the designed LFC has faster response speed and better robust performance. [ABSTRACT FROM AUTHOR]

Objective: To investigate the effects of 80-kilovoltage (kV) tube voltage coronary computed tomographic angiography (CCTA) with a reduced amount of contrast agent on qualitative and quantitative image quality parameters and on radiation dose in patients with a body mass index (BMI) <23.0kg/m2. Methods: One hundred and twenty consecutive patients with a BMI <23.0kg/m2 and a low calcium load undergoing retrospective electrocardiogram (ECG)-gated dual-source CCTA were randomized into two groups [standard-tube voltage (120-kV) vs. low-tube voltage (80-kV)]. The injection flow rate of contrast agent (350mgI/mL) was adjusted to body weight of each patient (4.5–5.5mL/s in the 120-kV group and 2.8–3.8mL/s in the 80-kV group). Radiation and contrast agent doses were evaluated. Quantitative image quality parameters and figure of merit (FOM) of coronary artery were evaluated. Each coronary segment was evaluated for image quality on a 4-point scale. Results: Compared with the 120-kV group, effective dose and amount of contrast agent in the 80-kV group were decreased by 57.8% and 30.5% (effective dose:2.7±0.5vs. 6.4±1.3mSv; amount of contrast agent:57.1±3.2 vs. 82.1±6.1mL; both p <0.0001), respectively. Image noise was 22.7±2.1HU for 120-kV images and 33.2±5.2HU for 80-kV images (p <0.0001). Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) in the proximal right coronary artery (RCA) and left main coronary artery (LMA) were all lower in 80-kV than 120-kV images (SNR in the proximal RCA: 16.5±1.8 vs. 19.4±2.8; SNR in the LMA: 16.3±2.0 vs.19.6±2.7; CNR in the proximal RCA: 19.4±2.3 vs.22.9±3.0; CNR in the LMA: 18.8±2.4 vs. 22.7±2.9; all p <0.0001). FOM were all significantly higher in 80-kV than 120-kV images (proximal RCA: 146.7±45.1 vs. 93.4±32.0; LMA: 139.1±47.2 vs. 91.6±31.1; all p <0.0001). There was no significant difference in image quality score between the two groups (3.3±0.8 vs. 3.3±0.8, p =0.068) despite decreased SNR and CNR of coronary artery in the 80-kV group. Conclusion: The 80-kV protocol significantly reduces radiation and contrast agent doses in CCTA in patients with a low BMI <23.0kg/m2 and a low calcium load while maintaining image quality. [ABSTRACT FROM AUTHOR]

Highlights: [•] We have investigated WOLEDs with single emission layer. [•] WOLEDs with low operating voltage and high color stability are demonstrated. [•] WOLEDs with high efficiency and low efficiency roll-off are achieved. [ABSTRACT FROM AUTHOR]

Abstract: We have investigated the effect of boron (B) and phosphorus (P) compensation on the performance of Czochralski (CZ) silicon solar cells. Both majority and minority carrier mobilities are significantly reduced by the dopant compensation. Correspondingly, the minority carrier diffusion length becomes smaller. The compensated silicon solar cells show weaker spectral responses and therefore lower short-circuit current. However, the open-circuit voltage can be influenced by the net doping concentration in our silicon wafers. A higher open-circuit voltage could be obtained from the compensated solar cells due to its larger net doping concentration. As a result, the compensated solar cells could have the same efficiency as the conventional ones. It suggests that the dopant compensation in silicon with a doping level of ≤1017 cm−3 is not a serious issue for the improvement of solar cell efficiency. The results are of significance for the upgraded metallurgical grade silicon (UMG-Si) application in the fabrication of high efficiency and low-cost solar cells. [Copyright &y& Elsevier]