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In this paper, we consider covering graphs obtained by lifting a tree with a loop at each vertex as a voltage graph over a cyclic group. We generalize a tool of Hell et al. (2020), known as the billiard strategy, for constructing Hamiltonian cycles in the covering graphs of paths. We show that our extended tool can be used to provide new sufficient conditions for the Hamiltonicity of covering graphs of trees that are similar to those of Batagelj and Pisanski (1982) and of Hell et al. (2020). Next, we focus specifically on covering graphs obtained from trees lifted as voltage graphs over cyclic groups Z p of large prime order p. We prove that for a given reflexive tree T whose edge labels are assigned uniformly at random from a finite set, the corresponding lift is almost surely Hamiltonian for a large enough prime-ordered cyclic group Z p. Finally, we show that if a reflexive tree T is lifted over a group Z p of a large prime order, then for any assignment of nonzero elements of Z p to the edges of T , the corresponding cover of T has a large circumference. [ABSTRACT FROM AUTHOR]

Hydroxylamine nitrate (HAN)-based liquid propellants are characterized by high energy content and low toxicity ionic monopropellants, offering great potential application prospects in the space engine. This paper proposes an experimental system for electric ignition and combustion of HAN-based liquid propellant. The energy for decomposition, current, and combustion image of HAN-based liquid propellant are measured under different initial voltage, propellant volume, and the initial pressures in Ar and air atmospheres. The results show that the energy for decomposition decreased with an increase in initial voltage, propellant volume, and initial pressure. An increase in the initial voltage accelerates the reaction speed of HAN-based liquid propellant, and the energy for decomposition is approximately 3 J. An increase in the propellant volume decreases the equivalent resistance in the circuit, increasing the current and enhancing the thermal effect of the propellant. The accumulation of decomposition products and heat under high pressure reduced the energy for decomposition; the energy for decomposition is less than 1.5 J for the pressurization condition. Compared with the Ar atmosphere, the energy for decomposition of HAN-based liquid propellant shows better stability in the air atmosphere. The flow combustion device of HAN-based liquid propellant for the flow state is designed. The HAN-based liquid propellant is successfully ignited for different initial voltages and flow rates. The research results provide a reference for the design of space engine for HAN-based liquid propellant based on the electric ignition method. • Experiments for HAN electric ignition on different initial U , V , P were carried out. • The effects of initial conditions on the ignition energy of HAN was studied. • The comparison of ignition energy in air atmosphere and Ar atmosphere was analyzed. • The propellant flow combustion based-on the electric ignition method was achieved. [ABSTRACT FROM AUTHOR]

• A model for the bending of the ssDNA-microbeam with surface charge effect is established. • The electric potential distribution is calculated by using finite difference method and Newton's iteration method. • The surface charge density can modulate the bending of the ssDNA-microbeam. A unified energy model for mechanical deformation of the microbeam included by single stranded DNA (ssDNA) adsorption considering the surface charge density on substrate is investigated. First, a free energy model is established to quantify the deflection and axial displacement of the microbeam, the ion concentration in the solution, as well as the electric potential distribution inside and outside the ssDNA film with a uniform surface charge density. Then, the governing equations and corresponding boundary conditions are obtained by minimizing the free energy with three types of variational variables. And, the relationship of the electric potential difference between the two sides of the ssDNA film and the deformation of microcantilever and simply support beam are determined in different solutions (1: 1, 1: 2, 1: 3). Moreover, the numerical solutions of the electric potential distribution inside and outside the ssDNA film are investigated by using the finite difference method and Newton's iteration method. The results suggest that the nonlinear model for electric potential distribution should be used under higher surface charge density. By fitting and comparing the present predictions with Arroyo-Hernandez's experimental data, the effectiveness of the model is verified. The study shows that the surface charge density can modulate the magnitude and direction of ssDNA-microbeam deformation, which also indicates that there exists a critical surface charge density, causing the failure of ssDNA-microbeam detection. These conclusions are helpful for designing the efficient biosensors based on DNA-microbeam. [ABSTRACT FROM AUTHOR]

This paper introduces a novel Multi-Level Inverter (MLI) design which utilizes a single input and leverages capacitor voltages source to generate a four-fold increase in output voltage as the main problem that stays with the inverters is their low boost ability and efficiency while maintaining power quality at the same time. One capacitor is charged to match the input voltage magnitude, while the other two capacitors store twice this magnitude. Through a series-parallel combination with switching operations, all capacitors are effectively charged and discharged within each cycle, ensuring natural voltage balance. A comprehensive comparative analysis is conducted to highlight the advantages of this innovative approach, particularly in terms of component reduction and mitigation of voltage stress. Detailed assessment of power losses within the proposed circuit is undertaken, simulation studies are first carried out while extensive experimentation verifies its operational efficiency under diverse conditions such as varying modulation indices, loads, and supply-side fluctuations with an impressive maximum efficiency of 96.9 % at a 200 W power rating, our research contributes to advancing compact power converters, addressing crucial challenges in modern power electronics applications, and paving the way for enhanced performance and reliability in such systems. [ABSTRACT FROM AUTHOR]

Partial shading deteriorates the overall performance of photovoltaic (PV) arrays by reducing the power output. Various shading mitigation strategies have been proposed in the literature with vulnerabilities of limited applications, switches, sensor counts, design, cost, and complexities. In this paper, a multi-string differential power processing (MS-DPP) based voltage equalizer is proposed for power output improvement in the PV arrays during shading. The equalizer is utilized for the series-parallel array which is equipped with a shading detection system achieved from the optimal placement of minimum sensor counts. The technique uses the concept of a switching capacitor that balances the voltage ratio between the modules of individual strings to ensure higher power generation and convex power curves during shading. The system is simulated and validated in MATLAB simulation and further verified on the OPAL-RT 4510 hardware-in-loop FPGA-based real-time platform. The technique is executed on three array sizes and compared with existing techniques under static and dynamic partial shading cases. The analysis shows that MS-DPP enhances the array power output with a conversion efficiency higher than 99 % during shading with lower system size and 98.38 % and 95.05 % reduced counts of switches and sensors than dynamic reconfigurations. • A multi-string differential power processing (MS-DPP) voltage equalizer for PV arrays is proposed. • MS-DPP ensures higher power generation with smoother power curves during partial shading. • Validated in MATLAB and OPAL-RT environment under shading cases for multiple arrays. • Compared with conventional systems, power optimizer, static and dynamic reconfigurations. • Power conversion efficiency of higher than 99 % with 98.38 % and 95.05 % less switches and sensors than dynamic reconfiguration. [ABSTRACT FROM AUTHOR]

This paper introduces a novel droop-based decentralized control scheme to address the power-sharing challenges within a PV-fed islanded AC microgrid. This novel approach integrates both conventional (P-f/Q-V) and virtual impedance concepts to optimize and manage the precise distribution of active and reactive power among parallel operating inverters posing a significant research challenge. The conventional droop control methods encounter limitations such as voltage and frequency deviations and inaccuracies in power-sharing due to line impedance disparities. To overcome these limitations, the proposed solution integrates an enhanced virtual impedance control loop alongside the conventional control loop (P-f/Q-V). The efficacy of this approach is showcased through simulations conducted using the OPAL-RT OP4510 simulator within the MATLAB/Simulink platform. The Real-time simulation outcomes confirm the efficiency of the suggested control strategy, guaranteeing precise distribution of both active and reactive power while upholding stable voltage and frequency profiles within the system. • A novel virtual impedance structure for improved power sharing capability among parallel inverters. • PCC voltage stability under load change and line impedance mismatch scenarios. • Restoration of AC MG frequency under load transient condition. • An analytical solution for choosing the equivalent output virtual impedance. [ABSTRACT FROM AUTHOR]

Multilevel inverters produce waveforms that lead to better power quality. Switched-capacitor inverters are one kind that is capable of generating boosted voltage and encourages a single-stage grid-tied inverter solution. In this paper, a four-times boost nine-level inverter with fewer switches is presented in standalone and grid-connected mode. Two switched capacitors, along with eleven switches and one diode, are employed to generate the required boosted nine-level output. The circuit modulation allows self-charging of the capacitors, with the first capacitor charging to the DC source and the second charges to twice of it by shunting it with the combination of the first capacitor voltage and the DC source. This inverter's application can be as a solar PV microinverter due to its fewer components and small filter requirement. The topology is compared with the single-source nine-level inverters and exhibits the lowest cost of all quadruple boost inverters. The presented inverter operation is verified in Simulink and validated on the laboratory prototype. Further, to minimize the leakage current, the circuit is modified accordingly and tested in a hardware-in-the-loop environment. [ABSTRACT FROM AUTHOR]

This article investigates the free vibration behavior of functionally graded porous reinforced with graphene platelets magneto-electro-elastic (FGP-GPL-MEE) plates. The FGP-GPL-MEE plate is supported by the Winkler-Pasternak foundation and subjected to the initial external electric voltage and magnetic loads. The governing equations for FGP-GPL-MEE plates are derived from the combination of Hamilton's principle and the refined plate theory (RPT) with four variables. The FGP-GPL-MEE plate is formed by combining three porosity distributions of functionally graded materials and three patterns of graphene platelets dispersion distributed along the plate thickness. Using the modified Halpin-Tsai model, effective material properties of the FGP-GPL-MEE plate are estimated. Isogeometric approach (IGA) is used to discretize the plate geometry and extract mode shapes and natural frequencies. The effects of various parameters such as porosity distributions, porosity coefficient, GPLs distributions and magnetic and electric potentials on the natural frequencies of the FGP-GPL-MEE plate are performed. The results indicate that the GPLs reinforcement can be significantly enhanced the natural frequencies of the FGP-GPL-MEE plate. Moreover, the free vibration behavior is significantly influenced by porosity, as well as magnetic and electric fields. The results of this study provide valuable insights into the vibrational characteristics of FGP-GPL-MEE plates. [ABSTRACT FROM AUTHOR]

Ceramic PZT95/5 lies near the boundary between the ferroelectric and antiferroelectric phases and undergoes complex domain switching and various phase transitions in response to temperature, pressure, and electric fields. This phenomenon often leads to unusual performances, making it challenging to characterize and control the electromechanical properties of the material. In particular, the phase transition from ferroelectric rhombohedral to antiferroelectric orthorhombic is caused by the combined effect of polarization switching and oxygen octahedral tilt. However, the underlying mechanism of their interaction is still unclear, resulting in a lack of thermodynamic models for ferroelectric-antiferroelectrics in multifield settings. In this study, a thermodynamic model was established by considering the combined effect of oxygen octahedral tilt, polarization, and stress, which can describe the polarity characteristics of phase transitions in PZT95/5 under multiple fields. This model comprehensively accounts for all phases of PZT95/5 and successfully simulates the experimental phase diagram of PZT95/5 under hydrostatic pressure. The tilt angle of the oxygen octahedra and the polarization were incorporated to reveal the special polarity microstructure of the intermediate phase between the ferroelectric and antiferroelectric phases and determine the effect of pressure on the incommensurate modulations. Exploring the application of antiferroelectric materials in smart devices via the pressure-induced transition of incommensurate modulation phases may become a new possibility. [ABSTRACT FROM AUTHOR]

This study presents a novel voltage control strategy for low voltage (LV) distribution grids, addressing the lack of coordination between photovoltaic (PV) reactive control and energy storage system (ESS) active control. The proposed strategy concentrates on group coordination of PV and ESS to improve LV grid performance. Initially, it suggests employing PV reactive power for voltage regulation before utilizing ESS active power, relying on the voltage cost sensitivity factor (VCSF) of different regulating devices, to reach efficient PV resource utilization. Devices are categorized by their VCSF, prioritizing groups with larger VCSF for voltage regulation, enhancing overall coordination. In the PV reactive voltage regulation stage, the reactive power utilization rate is the consensus variable, while in the ESS active control stage, the change in state of charge (SOC) is the consensus variable, collectively working towards desired voltage regulation and SOC change. Coordinated control is utilized to converge key node voltages to set values and obtain effective LV grid voltage regulation. An IEEE 14-node LV grid simulation incorporating PV and ESS validates the proposed strategy, demonstrating its effectiveness and correctness in improving voltage control performance. The strategy achieves 70.56% of the capacity and 81.45% of the setup cost compared to similar research, with associated costs limited to 15.80% and 35.0% of accumulated costs. • New voltage control strategy for LV grids, coordinating PV reactive control and ESS active control. • Introducing voltage cost sensitivity factor (VCSF) for optimal PV and ESS utilization. • Group regulating devices by VCSF for effective voltage control in LV grids. • Use reactive power rate and state of charge changes for PV and ESS group consensus. • Validated strategy with IEEE 14-node LV grid simulation, improving voltage control performance. [ABSTRACT FROM AUTHOR]

Electrochemical machining (ECM) technology holds significant potential for applications in high accuracy engineering and manufacturing. To confine the electrolyte region during ECM and mitigate the effects of reaction products and heat generation, an electrolyte suction tool has been proposed. However, the complex electric field distribution on the anode surface during the application of pulse voltage, limits the further utilization of ECM with suction tool. A multi-physics simulation model is established to calculate the region of electrolyte confinement by the suction tool, current density distribution within the electrolyte region, and material removal. The model considers the combined effects of polarization and double layer, and all key parameters are calibrated through classical electrochemical testing experiments rather than fitted based on the predicted results. This study elucidates the transient response of current density on the anode surface during the application of pulse voltage. The simulation accuracy is validated by comparing experimental and simulated current waveforms, as well as material removal profiles under different pulse parameters and electrode shapes. This research is of great significance for improving surface precision and controllability of complex structures in ECM with suction tool, promoting its further application in the field of precision machining. • Establish a multi-physics field coupled simulation for ECM with electrolyte suction tool. • Calibrate all key parameters through classical electrochemical testing experiments. • Elucidate the transient response of Faraday current density on the anode surface during pulse voltage. • Elucidate the material removal mechanism under the combined effects of polarization and double layer. [ABSTRACT FROM AUTHOR]

Unipolar electrograms (uni-EGMs) are an essential part of intracardiac mapping. Although Wilson central terminal (WCT) is conventionally used as a reference for signals, avoidance of contamination by far-field and nonphysiologic signals is challenging. The aim of the study was to explore the impact of an intracardiac indifferent reference electrode close to the recording electrodes, in lieu of WCT, on electrograms. Sinus node activation was mapped in patients undergoing catheter ablation by a multielectrode array with a close indifferent electrode (CIE) embedded in the distal end of the catheter shaft. An equal number of points was sequentially acquired at each site with use of CIE as a reference first and subsequently with WCT. Uni-EGMs, bipolar EGMs, and the earliest activation area (defined as the area activated in the first 10 ms of the beat) were compared between CIE- and WCT-based activation maps. Seventeen patients (61 ± 18 years; 76% male) were studied. Uni-EGM voltages acquired with CIE were significantly larger than (n = 11) or comparable to (n = 4) those acquired with WCT. When points from the entire cohort were analyzed altogether, unipolar voltages and their maximum negative dV/dT and bipolar voltages recorded with CIE were significantly larger than those recorded with WCT (2.36 [1.42–3.79] mV vs 1.96 [1.25–3.03] mV, P <.0001; 0.40 [0.18–0.77] mV/s vs 0.35 [0.15–0.71] mV/s, P <.0001; and 1.46 [0.66–2.81] mV vs 1.33 [0.54–2.64] mV, P <.0001, respectively). The earliest activation area was significantly smaller in CIE-based activation maps than in WCT-based ones (0.3 [0.7–1.4] cm2 vs 0.6 [1.0–1.8] cm2, P =.01). CIE-based maps were associated with an approximately 20% increase in unipolar voltage and may highlight the origin of a focal activation more clearly than WCT-based ones. [Display omitted] [ABSTRACT FROM AUTHOR]

The paralleled configuration of three-phase two-level (3P2L) inverters has been put forward to increase the output power rating, operating efficiency, and system reliability. Nevertheless, this architecture brings about the serious circulating current problem, which distorts the quality of output currents, results in additional power losses, and reduces the system efficiency. Another problem is the common-mode voltage (CMV), which causes electromagnetic interference and threatens the safe operation of the system. There exists interconnection between these two issues in the paralleled 3P2L inverters. To suppress the CMV and circulating current simultaneously, an improved control method is presented. At first, the discrete model of paralleled 3P2L inverters is established, based on which the improved control method is designed to restrain the circulating current, while the parameter tuning is avoided. In addition, the zero-sequence component injection associated with the optimized configuration of carrier phase is conducted, and the CMV magnitude of each inverter is limited within one-sixth of dc-side voltage. When comparing with the traditional space vector modulation (SVM) approach, the CMV magnitude is restrained by two-thirds by the presented method. The hardware-based evaluation results have been provided to validate the presented approach. • This article investigates a control method for paralleled three-phase inverters. • The control parameters are directly obtained by the discrete model. • The configuration of carrier phase is optimized to reduce common-mode voltage. [ABSTRACT FROM AUTHOR]

The focus of this study is to investigate the critical matter of voltage sags in power systems, which have a substantial adverse effect on both the functionality of equipment and the quality of power. Central to this investigation is the integration of hydrogen fuel cells and a D-STATCOM system, which is suggested as a substitute approach for mitigating voltage fluctuations. The hydrogen fuel cell serves as the pivotal component, renowned for its ability to significantly improve power quality through the efficient mitigation of voltage sag concerns. The paper provides a comprehensive analysis of the contribution that hydrogen fuel cell integration with D-STATCOM makes to the reliability of power systems. A systematic methodology is employed, supported by simulations and modeling, to emphasize the critical significance of hydrogen fuel cells in surmounting obstacles related to voltage injection and enhancing power quality. By utilizing a Type-3 Fuzzy system, the research evaluates the dependability of the control system and proposed model. The effectiveness of this method, which is focused on hydrogen fuel cells, is verified by means of MATLAB simulations, which demonstrate its superior performance in comparison to conventional PI and ANFIS controllers. • Integrates hydrogen fuel cells with D-STATCOM for improved power quality. • Achieves notable reduction in voltage sags in power systems. • Enhances power system reliability and stability. • Employs Type-3 Fuzzy system for advanced control. • Validated by MATLAB simulations, outperforming traditional controllers. [ABSTRACT FROM AUTHOR]

The proliferation of virtual synchronous generator (VSG) technology within series-compensated double-fed induction generator (DFIG)-based wind farms is substantially hampered by the attendant risk of subsynchronous control interaction (SSCI), resulting in a significant research deficiency on systematic control interaction analysis and the development of mitigation strategies. The paper proposes an advanced active disturbance rejection control (ADRC) framework, incorporating real-time compensation mechanisms to mitigate the inadequate suppression efficacy attributable to the VSG's diminished output impedance. Initially, the mathematical expression for the VSG output impedance is rigorously deduced, and the positive damping attributes of the VSG in relation to SSCI are elucidated from the perspective of underlying mechanistic principles. Subsequently, the suppressive mechanism of SSCI by the ADRC is revealed in the context of VSG involvement, and the consequent augmentation of SSCI attributed to PI control is systematically derived. In immediate succession, the quanta of oscillation and inductive cross-coupling are encapsulated as the system's aggregate disturbance, thereby streamlining the ADRC to its primary order configuration, permitting the utilization of an extended state observer (ESO) for the dynamic estimation of said disturbance. Furthermore, a fractional-order filter function is instituted to engineer an augmented ESO, which refines the output voltage of the grid-side converter. Concurrently, a meticulous discourse on the rectification strategy for the proposed ESO parameters and its stability ensues. Ultimately, the efficacy of the mechanism analysis, alongside the robustness of the proffered control strategy for SSCI mitigation under diverse perturbation conditions, is corroborated via impedance evaluation and time-domain simulation. • The VSG characterizes positive impedance and can provide positive damping. • The suppression mechanism of SSCI by ADRC is deduced under the VSG control. • An advanced ADRC with estimation and compensation is proposed to mitigate SSCI. • The Fal function filter is established to optimize the output voltage in the GSC. [ABSTRACT FROM AUTHOR]

Three-level T-type converters are necessary interfaces for distributed energy resources to interact with the public grid. Naturally, designing a control strategy, featuring superior dynamics and strong robustness, is a promising solution to guarantee the efficient operation of converters. This article presents an improved finite-time control (IFTC) strategy for three-level T-type converters to enhance the dynamic performance and anti-disturbance capacity. The IFTC strategy integrates a dual-loop structure to regulate the dc-link voltage and grid currents. Specifically, the voltage regulation loop employs a finite-time adaptive controller that can counteract load disturbances without relying on current sensors. In the current tracking loop, finite-time controllers combined with a command filter are constructed to obtain fast and accurate current tracking. In this loop, the command filter is utilized to avoid calculating the derivative of current references. Theoretical analysis and experimental results demonstrate the IFTC strategy's effectiveness. • It aims to achieve fast finite-time tracking control of three-level T-type converters. • The proposed improved finite-time control (IFTC) strategy integrates a dual-loop structure. • The IFTC enhances the robustness against load disturbances and parameter uncertainties. • Both theoretical analysis and experimental results confirm its effectiveness. [ABSTRACT FROM AUTHOR]

To measure the electrical parameters of 25Hz phase-sensitive track circuit, a testing instrument with STM32 microcontroller as the control core is designed. It mainly uses the method of root mean square and fast Fourier transform to measure the effective value of the coil voltage of the track relay and the phase difference between the coil voltage of the track relay and the local coil voltage. The voltage waveform and calculation results are displayed on TFT-LCD, which has the advantages of simple structure, fast processing speed and high measurement accuracy. It is convenient for the daily detection and fault diagnosis of 25Hz phase-sensitive track circuit. [ABSTRACT FROM AUTHOR]

Room temperature water splitting due to reactive surface charges created by defects and porosity in metal oxides fabricated as Hydroelectric Cell (HEC) has translated it into electric current and voltage. Novel oxygen-deficient, nanoporous nanocomposites [(1- x) Na 0.5 Bi 0.5 TiO 3 - (x) MgFe 2 O 4 (x = 0, 0.2, 0.5, 0.8 and 1)] denoted as (1- x) NBT - (x) MFO used as multiferroic, have been prepared by solid state reaction for water splitting. NBT-MFO based hydroelectric cell has been fabricated to generate current and voltage by water splitting. Maximum offload current 8.23 mA and voltage 1 V has been recorded for 0.50NBT-0.50MFO nanocomposite based hydroelectric cell of area 2 × 2 cm2. Dissimilarity in ferroelectric-ferrite phase in nanocomposites generates strain in the perovskite phase evaluated by W–H plot analysis of X-Ray diffraction patterns. The validation of oxidation states of cations and the highest oxygen vacancies ratio of 80% has been calculated by X-ray photoelectron spectroscopy (XPS) peak area. The interstitial defects in nanocomposites have been analyzed by PL emission spectra. The actual charge transfer processes in HEC have been studied by circuit modeling of Nyquist plot by Electrochemical Impedance Spectroscopy (EIS). By virtue of utmost defects, highest nanoporosity and extremely low charge transfer impedance (1.169 Ω), nanocomposite 0.50NBT-0.50MFO delivered significant short circuit current. Furthermore, nanocomposites based HECs stand out as economical, facile and eco-friendly energy devices with no harmful by-products. [ABSTRACT FROM AUTHOR]

Memristors with metal/insulator/metal (MIM) double terminal structure have garnered significant attention as potential candidates for next-generation non-volatile memory devices. In this study, the Pt/Ni 0.5 Zn 0.5 Fe 2 O 4 /Pt (Pt/NZFO/Pt) composite films were fabricated and their resistive switching behaviors were modulated by varying the oxygen pressure. It was confirmed that the oxygen pressure influenced the films microstructure, morphology and oxygen vacancy concentration. The resistive switching characteristics of the Pt/NZFO/Pt composite films, including adjustable set/reset voltages, a broad memory window, and robust retention properties, were also regulated by the corresponding oxygen pressure. It is speculated that the resistive switching mechanism is due to the creation and disruption of conducting paths caused by the presence of oxygen vacancies and synergistic interplay of barrier modulation by oxygen vacancies and ferroelectric polarization. Consequently, the Pt/NZFO/Pt composite films, optimized at an oxygen pressure of 0.1 Pa, emerged as suitable candidates for memristor applications. [ABSTRACT FROM AUTHOR]

The control of Proton Exchange Membrane Fuel Cell (PEMFC) is exceptionally challenging due to its complex nonlinearity, slow dynamics and load disturbance. In this paper, an Adaptive Model Free Control (AMFC) approach is introduced for regulating the PEMFC output voltage under load perturbation and measurement noise conditions. The proposed method consists of four sub-elements. Firstly, an Extended State Observer (ESO) based on a Single-Input Interval Type-2 Fuzzy intelligent PI (SI-IT-2-FLC-iPI) scheme is designed to enhance the performance of PEMFC. Secondly, a Nonlinear Sliding Mode Control-based Super Twisting Algorithm (NSMC-STA) is used as an auxiliary control approach to reduce the estimation error and ameliorate the system robustness. Thirdly, a Forgotten Recursive Least Square Error (FRLSE) is applied for adjusting the physical parameter of MFC and further ameliorating the control response. Finally, all these elements are merged together within what it is called Ultra Local Model (ULM). Through extensive simulation, the efficacy of the proposed regulator in accurately tracking the output signal is showcased, outperforming conventional controllers with remarkable improvements. The system achieves 0.001 steady-state error, 0% overshoot and settling time of approximately 8.9 s, which is good enough in the context of standalone fuel cell applications. • An intelligent Model Free Control structure is developed for tracking the output voltage of PEMFC. • Integrating FLC type-2 PI, NSMC-STA, ESO and online tuner based FRLSE within ULM. • The finite stability is fully demonstrated using Lyapunov theorems. • The proposed control enhances the performance of PEMFC under various operating conditions. [ABSTRACT FROM AUTHOR]

Mechanically activated Piezo1 channels undergo transitions from closed to open-state in response to pressure and other mechanical stimuli. However, the molecular details of these mechanosensitive gating transitions are unknown. Here, we used cell-attached pressure-clamp recordings to acquire single channel data at steady-state conditions (where inactivation has settled down), at various pressures and voltages. Importantly, we identify and analyze subconductance states of the channel which were not reported before. Pressure-dependent activation of Piezo1 increases the occupancy of open and subconductance state at the expense of decreased occupancy of shut-states. No significant change in the mean open time of subconductance states was observed with increasing negative pipette pressure or with varying voltages (ranging from -40 to -100 mV). Using Markov-chain modeling, we identified a minimal four-states kinetic scheme, which recapitulates essential characteristics of the single channel data, including that of the subconductance level. This study advances our understanding of Piezo1-gating mechanism in response to discrete stimuli (such as pressure and voltage) and paves the path to develop cellular and tissue level models to predict Piezo1 function in various cell types. [ABSTRACT FROM AUTHOR]

Proton exchange membrane fuel cell (PEMFC) is a promising hydrogen technique with various application prospects. However, all the PEMFCs are subject to degradation resulting from mechanical and chemical aging. To tackle this challenge, accurately predicting fuel cell degradation is essential for its durability optimization. In this study, an enhanced data-driven prognostic framework is developed to accurately predict short-term and medium-term degradation using only fuel cell voltage as the input feature. Firstly, a local outlier factor (LOF) algorithm is adopted for automatic detection of outliers in raw data collected from actual sensing environments. Then, an advanced deep learning model, residual–CNN–LSTM-random attention, is proposed to optimize voltage prediction to better indicate future PEMFC degradation trend. The proposed work is validated by the IEEE PHM 2014 Data Challenge. Compared to state-of-the-art methods, the proposed framework provides superior prediction accuracies with high stability. For instance, the framework improves short-term prediction, achieving a root mean square error (RMSE) of 0.0021 and a mean absolute percentage error (MAPE) of 0.0323 at steady state when training stops at 600 h. For medium-term prediction, our method also attains better results with an RMSE of 0.0085 and a MAPE of 0.4237 under same working conditions. Additionally, the comparative analyses demonstrate a lower computational burden and higher suitability of proposed work for practical applications. • An enhanced deep learning model, residual–CNN–LSTM-random attention, is proposed. • The innovative degradation prognostic framework is developed based on above model. • The efficiency of framework is verified by steady-state and quasi-dynamic aging data. • The framework improves the prediction accuracies, while maintaining high stability. • Compared to state-of-the-art methods, our work is more suitable for application. [ABSTRACT FROM AUTHOR]

The generated output voltage resulting from the hydrovoltaic effect serves to directly suppress catalyst carrier recombination, thereby enhancing the process of photocatalytic water splitting. The principal challenge lies in establishing a seamless pathway for water that facilitates the synergistic interplay of the hydrovoltaic and photocatalytic effects. Laplace pressure, generating from a specific surface pattern, emerges as a compelling force capable of aiding the autonomous transport of water. Consequently, it enables the harmonious collaboration of hydrovoltaic and photocatalytic effects. In this article, a pioneering surface pattern comprised of TiO 2 (P25), characterized by a Laplace pressure differences, engenders a self-sustaining conduit for water transport, thereby instigating an enhanced hydrovoltaic effect. This, in turn, enhances the photocatalytic water splitting capability of P25. The resulting system is denoted as hydrovoltaic-effect-enhanced photocatalytic P25 (HP–P25). Notably, the hydrovoltaic effect voltage of P25 attains a new high at 5.5 V. Furthermore, this voltage facilitates the in-situ suppression of catalyst carrier recombination, leading to a 6.6-fold enhancement in the efficiency of photocatalytic water splitting. The demonstrated system thus introduces a novel and uncomplicated paradigm for the collaborative manifestation of hydrovoltaic and photocatalytic effects. [ABSTRACT FROM AUTHOR]

Metacomposites with negative permittivity have gained increasing momentum in recent years due to their unique electromagnetic characteristics and considerable potential application. However, how to adjust negative permittivity is still a big technical challenge to overcome. In this paper, silicon dioxide (SiO 2) ceramic metacomposites consisting of carbon fibers (CFs) were fabricated by vacuum hot press sintering, and their negative permittivity might be modified by adjusting the filler content and applying external direct current (DC) bias voltages. As the CF content increased, the electrical conductivity of composites increased markedly, and the conduction mechanism transformed to a metal-like conductivity from hopping conductivity. The permittivity values of composites with high CF contents were negative at the test frequency range owing to the appearance of a low plasmonic state of unbound electrons in the percolating carbon networks. The conductivity of the composites increased when DC bias voltage was applied, because some of the accumulated local electrons at the CF-SiO 2 interface could absorb energy and become free electrons. Larger bias voltages led to increased concentration of free electrons, so the absolute values of the negative permittivity raised according to the Drude model and the frequency band of negative permittivity became wider. This work presents an effective approach for adjusting the negative permittivity value and frequency band, which is advantageous in clarifying the realization and regulation mechanisms of negative permittivity. [ABSTRACT FROM AUTHOR]

The development of electricity generation from renewable sources, particularly photovoltaic energy (PV), as well as the significant growth of electric mobility with electric vehicles (EVs), leads us to contemplate the potential impacts of these components may have on an existing distribution electrical network. An electrical distribution network is designed to supply electrical loads in one specific direction while maintaining the quality of its technical parameters, such as current, voltage, and frequency. In this article, through a literature review, we will explore how the integration of each component, photovoltaic energy, and electric vehicles, individually and in combination, can impact the electrical distribution network. In addition, we will examine based on a literature review, the methods proposed by various authors to enhance the impacts occurring on the network due to this integration. [ABSTRACT FROM AUTHOR]

In this paper, a multi-objective cooperative (MOC) controller based on average consensus algorithm is designed to achieve rapid State-of-Charge (SoC) balancing, proportional load current sharing, and flexible DC bus voltage regulation for parallel battery storage units (BSUs) in shipboard DC microgrids. Different from the conventional secondary controllers, the designed MOC controller can simultaneously achieve the above three control objectives with a fully distributed manner without requiring multiple controllers, thereby effectively improving the system stability and reducing the communication burden. Furthermore, an optimized convergence factor is designed to accelerate SoC balancing, and pinning control is introduced to obtain flexible and accurate DC bus voltage regulation. The process of SoC balancing and current sharing analysis, SoC convergence performance analysis, large-signal stability analysis, and global steady-state analysis verifies the rationality and stability of the MOC controller. Finally, the Matlab/Simulink simulation and StarSim HIL experimental results demonstrate the effectiveness and robustness of the designed MOC controller in a shipboard DC microgrid under various testing scenarios. [Display omitted] • The MOC controller can achieve rapid SoC balancing, proportional load current sharing, and flexible bus voltage regulation. • An improved SoC balancing algorithm is developed to accelerate the SoC convergence speed. • The pinning control is introduced to flexibly regulate the DC bus voltage. [ABSTRACT FROM AUTHOR]

Air-cooled proton exchange membrane fuel cells (PEMFCs) are energy-converting devices suitable for various scenarios. In the present study, the dynamic response of voltage and temperature of an air-cooled PEMFC stack with 75 thermocouples is experimentally studied under different loading and fan-controlling strategies. It is found the larger the ramp increment or step amplitude, the greater the voltage overshoot/undershoot (reaching 5.09 V), the longer the response time (reaching 11.23 s), and the higher the voltage non-uniformity (reaching 20.20 %). Under the same current, the stack generally performs better in the unloading process than in the loading process. Too low (or too high) fan pulse width modulation (PWM) will lead to insufficient (or excessive) cooling capacity, resulting in stack overheating (or water flooding). For the stack studied, a relatively low PWM of 40 % at low current is more suitable, while under a medium or high current a PWM of 60 % leads to better cell performance. • A novel experimental setup with 75 thermocouples for an air-cooled PEMFC. • Effects of current loading ramp and amplitude on voltage and temperature dynamics. • Voltage overshoot/undershoot up to 5.09 V and response time up to 11.23 s. • Temperature non-uniformity up to 20.20 % and temperature deviation index up to 5.13 °C. • Optimal fan PWM of 40 %–60 % for different current densities. [ABSTRACT FROM AUTHOR]

An appropriate clamping pressure is required to ensure the gas-tight operation of a PEMFC assembly and to improve the contacts (i.e. mechanical, thermal, electrical) between its components. However, an excessive mechanical load may also worsen the cell performance, in particular through the reduction in the porosity and mass transport ability of the Gas Diffusion Layers. In this study, the effects of mechanical compression on the global performance of a 225 cm2 PEMFC assembly are investigated by implementing cell voltage monitoring and polarisation curve measurements. The investigations are carried out with gradual increase / decrease and randomised load compression protocols applied using a specially designed mechanical compression unit. 12 levels of mechanical compression are considered, ranging from 0.35 to 2 MPa with steps of 0.15 MPa. The results of the characterisation techniques show that the PEMFC performance is improved at all tested operating conditions for mechanical compression up to 1.55 MPa. This finding is attributed to the dominant reduction of the ohmic drop against the increase of the gas diffusion losses. It is also shown that compressing the PEMFC beyond 1.55 MPa would not lead to any further improvement of the global cell voltage output. This may even worsen the cell electrical characteristics by affecting its mass transport issues. [Display omitted] • The effects of clamping on the global performance of a 225 cm2 PEMFC are studied. • A cell compression unit is used to duplicate various mechanical loads (0.35–2 MPa). • Investigations are done using cell voltage monitoring and polarisation curves. • In all cases, the PEMFC performance is improved for mechanical load up to 1.55 MPa. • The tests are correlated with ex-situ characterisations of GDL contact resistances. [ABSTRACT FROM AUTHOR]

Polycrystalline cubic boron nitrides (PcBN) have been increasingly used together with PVD coatings, mainly for hard turning operations. Within this context, effectiveness of coated PcBN as cutting tool is usually addressed by evaluation of its machining performance. Meanwhile, studies aiming to assess and understand the correlation between microstructural features and mechanical behaviour of the coating-substrate system are rather limited. Aiming to overcome such lack of information, in this study the influence of substrate bias voltage (−35 V as compared to −60 V) and microstructural assemblage (as a function of cBN content and binder chemical nature) on the mechanical integrity of TiAlN-coated PcBN systems is investigated. In doing so, contact damage response and coating adhesion strength of different coated-PcBNs are evaluated by means of indentation testing using distinct loading conditions (static and sliding) and tip geometries (spherical and conical). Such testing program is complemented by detailed FESEM inspection of the involved failure micromechanisms, as well as microstructural and micromechanical characterization of the deposited films. Results indicate that resistance against crack nucleation and propagation of coated PcBN, induced by either spherical or conical indentation, is enhanced by using harder (high content of cBN particles) and tougher (metallic binder) substrates (H-PcBN). Regarding bias voltage, systems with coatings deposited using a higher value (−60 V as compared to −35 V) show improved adhesive strength, this being particularly true for combinations involving low cBN content and ceramic binder substrate (L-PcBN). Similar beneficial effect was found, but exclusively in coated L-PcBN systems, regarding resistance to radial cracking emergence and to material removal through cohesive-failure chipping induced in Rockwell C tests. Although these findings are linked to the higher compressive residual stresses exhibited by coatings deposited under −60 V bias voltage, the latter does not translate in significant changes in microstructural and intrinsic mechanical properties of the TiAlN coating itself. [ABSTRACT FROM AUTHOR]

Power parameters are of importance to determine the microstructure and property of coatings deposited by cathode plasma electrolytic deposition (CPED). In the present study, the effect of power parameters including voltage and duty cycle on the microstructure and anti-corrosion property of zirconia (ZrO 2) CPED-coatings was investigated. The results suggested that the as-deposited coatings consisted of t -ZrO 2 and m -ZrO 2 , while the content of t -ZrO 2 exceeded 50 %. The content of t -ZrO 2 increased with the increase of voltage and decreased with the increase of duty cycle, reaching a maximum of 89.9 %. In addition, as the voltage and duty cycle increased, the porosity of the coating increased from 3.7 % to 15.5 %. Due to the high t -ZrO 2 content, high thickness and relatively dense structure, the coatings deposited at 250 V had a superior corrosion resistance in 3.5 wt% NaCl solution. This work will provide a guideline for tailoring high performance ZrO 2 CPED-coatings. [ABSTRACT FROM AUTHOR]

Induction motors (IMs) are extensively used in industrial sector. This kind of machine is subjected to several stresses that could interrupt their normal operation. An excessive stress can generate some symptoms before the IM fall in failure situation. Therefore, incipient detection of these symptoms permits the shutdown of IMs in order to avoid total destruction. Fault detection is then the main objective of diagnosis systems. Stator inter-turn short-circuits (SITSC) constitutes an important amount of cause of IM breakdown. However; unbalance supply voltage (USV) is one of the advantageous factors that affect IMs operation. Thus, in order to avoid false alarm induced by USV, the diagnosis system must make difference between USV and SITSC faults. This paper presents an efficient approach to estimate SITSC percentage and detect USV occurrence using Artificial Intelligent (AI) tool. Artificial neuronal network (ANN) plays the key-role of the proposed diagnosis system. A fault Classifier of SITSC and USV is carried out using multi-layer perceptron neuronal network (MLP-NN). The training, testing and validation phases of MLP-NN need the dataset creation. The required data is obtained from both simulated mathematical model of IM and laboratory test-bed. The reached results show the sensitivity and the well-functioning of the proposed diagnosis system. • The detection of Stator Inter-Turn Short-Circuits fault is much more based on its severity and location. • The presence of Unbalanced Supply Voltage makes us unable to know whether there is a SITSC fault or not; that's why identification of Unbalanced Supply Voltage is also very important. • The challenge of this work is to estimate the percentage of Stator Inter-Turn Short-Circuits and detect the presence Unbalanced Supply Voltage utilizing only current & voltage signals. • An MLP-NN is created and simulated for a mathematical model of the motor; in order to choose the appropriate architecture and to verify the efficacy of the proposed diagnosis system. • In the experimental investigation, no additional sensors are required since the terminal voltage and current measurements are sufficient. • the experimental investigation is adopted in order to prove the effectiveness of MLP-NN by using untreated cases of Stator Inter-Turn Short-Circuits fault and Unbalanced Supply Voltage. • The work in the paper has been compared to similar ones, and it has been found that the proposed method is efficient and has good accuracy compared to the others. • The work in the paper can be implemented on microcontroller due to its simplicity. [ABSTRACT FROM AUTHOR]

The performance of different applied voltages on the biomethanation of lignite is investigated in microbial electrolytic cells coupled with anaerobic digestion (MEC-AD). The cumulative methane production is only 35.1 mL/g lignite in the control reactor. However, the cumulative methane production is increased to 44.3 mL/g lignite in the MEC-AD reactor at the applied voltage of 1 V, and followed by 62.6 mL/g lignite (2 V), 102.8 mL/g lignite (4 V), and 123.8 mL/g lignite (8 V). The 3D fluorescence spectra further clarified that the applied voltage favored the hydrolysis of macromolecular organic matter such as humic acid in lignite. The microbial community abundance in the bulk solution shows that some specific microorganisms such as electroactive bacteria (Chloroflexi) and hydrogenotrophic methanogenic archaea (Methanobacterium) were well enriched in the MEC-AD reactors. These results indicate that MEC-AD facilitates direct interspecies electron transfer (DIET) between electroactive bacteria and archaea, and significantly increases methane production. However, the economic analysis concludes that the methane production at the applied voltage of 8 V could not compensate for the cost incurred by electricity. The MEC-AD reactor with an applied voltage of 4 V showed excellent biomethanation characteristics of lignite, which provides a basis for the resource utilization of lignite. • MEC-AD system promotes the production and biodegradation of humic acid from lignite. • Hydrogenotrophic methanogenic archaea in MEC-AD are well enriched in bulk solution. • MEC-AD system significantly enhance the DIET for methane production from lignite. • The applied voltage of 4V performs better lignite biomethanation and economic benefit. [ABSTRACT FROM AUTHOR]

Photovoltaic (PV) energy has become a considerably more attractive source of power, with costs continually declining. Along with the implementation of this sustainable energy system, the power supply stability should be extensively investigated, particularly in off-grid systems where electricity storage becomes a limitation. The performance of the standalone photovoltaic battery system (SPVBS) is mainly reliant on the DC-bus voltage and its capacitor. The shortcomings of utilizing a small film DC-bus capacitor in SPVBS include the instability and low-frequency ripple of DC-bus voltage and the system's dynamic MPPT techniques performance. Therefore, this study proposes a new technique of regulating the various system components that stabilizes the DC-bus voltage, extracts stable output power despite harsh sudden load and radiation fluctuations, and maintains the system's functionality with or without the battery storage system (BSS). The proposed approach uses a hybrid salp swarm algorithm and particle swarm optimization (SSA-PSO) combined with an intelligent direct sliding mode controller (DSMC) to eliminate the instability and ripples of DC-bus voltages. Moreover, it employs DSMC for bidirectional DC-DC converter and boost converters to enhance the system's dynamic MPPT techniques capabilities. Four different modes are considered according to the energy availability, demand, and battery's state of charge (SOC). Additionally, this easy-to-use technique keeps the DC-bus voltage stable even when the battery storage system is not available. Simulation and experimental results revealed the resilience performance of the proposed intelligent SSA-PSO-DSMC technique in terms of DC-bus regulation, output power extracted, and current harmonics reduction compared to PSO, SSA, cuckoo search optimization (CSO), and grey wolf optimization (GWO). • A novel SSA-PSO-DSMC control is designed for PV converter to achieve MPPT and regulate DC-bus voltage. • The performance of SSA-PSO-DSMC controller was investigated on several stringent and realistic environmental profiles. • SSA-PSO-DSMC improves global MPP tracking speed and dynamic performance. • HIL experiment validates the implementation feasibility. [ABSTRACT FROM AUTHOR]

Fuel-cell-based, hydrogen-driven aircraft can significantly reduce the climate impact of aviation but the low ambient pressures at high altitude negatively affect the performance of fuel cells. The influence of low pressures on the behavior of a direct hybrid-system that connects a fuel cell and a battery without a DC/DC converter, is examined and compared to a fuel-cell-only system. Low ambient pressure leads to a reduced fuel cell voltage and power output. The voltage change between maximum voltage and the voltage level at the operational power increases with a decreasing air pressure for both the hybrid-system and the fuel-cell-only system. However, in a direct hybrid, the battery stabilizes the system voltage level and the voltage decrease is significantly smaller for the hybrid-system than for the fuel-cell-only system. At an ambient pressure of 300 mbar, the voltage variation of a 4 kW system is 96% lower for a hybrid-system compared to a fuel-cell-only system. The lower pressure also reduces the power output of the fuel cell. In the direct hybrid the battery contributes a demand related share of power and the contribution from the fuel cell decreases with air pressure as the contribution of the battery rises. [Display omitted] • Influence of pressure dependent fuel cell behaviour on direct hybrid system is shown. • Influence of low pressure on voltage variation within a direct hybrid is analysed. • Low ambient pressure increases voltage variation especially in fuel cell only systems. • Direct hybridisation stabilizes the voltage. • Low ambient pressure reduces power contributed by fuel cell in a direct hybrid. [ABSTRACT FROM AUTHOR]

The three-phase four-wire voltage source inverter (3P4W VSI) is widely used in applications like uninterrupted power supply (UPS) and bidirectional onboard charger. The increasing power density demand requires higher switching frequency and lower switching loss. To fulfill the conflicting objectives, two-fold methodology is proposed in this paper: 1) SiC/Si hybrid switches (HyS) together with recently reported gate trigger are reported for the first time in the 3P4W VSI; 2) the natural point voltage is controlled to track a sinusoidal voltage with the frequency equal to 3 times of fundamental frequency in order to achieve higher DC-bus voltage utilization rate, and further reduce the switching loss. The traditional PI controller is very hard to achieve desired performance due to both the nonlinearity and the variant reference of the natural point voltage control system. Thereby, the super-twisting sliding mode control (ST-SMC) is proposed in this paper to achieve desired tracking performance and fast dynamic response. The effectiveness and superiority of the system are verified by both simulation and experiment comparison with the existing methods using a 5 kW prototype. • A new trigger circuit proposed recently is used for the first time in a 4 legs inverter. • The relationship of DC-bus voltage and HyS switching loss is derived and testified. • The super-twisting sliding mode control achieves high tracking accuracy in 3P4W inverter. • HyS and suitable controller comprehensively improve the performance of 3P4W inverter. [ABSTRACT FROM AUTHOR]

• Split DC link balancing problem is discussed. • Dynamics of partial DC link voltages is derived. • Factors forcing DC link imbalance are analyzed. • Expression for optimal modulating signals zero-sequence component is obtained. Three-phase three-level AC/DC and DC/AC converters have demonstrated several advantages over their classical two-level counterparts such as better efficiency, enhanced total harmonic distortion, lower dv/dt and lesser overall chip area. T-type and neutral point clamped (NPC) topologies dominate the family of three-phase three-level converters, widely used in 10kVA – 100kVA power range. However, control of three-level converters is more complicated than of their classical two-level counterparts due to necessity of adopting an additional voltage loop, aimed to balance partial split DC link voltages. Moreover, the latter contain multiples of triple-base-frequency harmonic ripple even under balanced AC-side operation (this does not happen in two-level converters), which should be minimized by the balancing loop mentioned above. The nature of partial DC link ripple formation was analyzed in-depth for unity power factor operation, yet hardly extended to non-unity power factor cases. Moreover, inaccurate conclusions were drawn in some of the related studies. Consequently, this paper focuses on comprehensive modeling and formulation of split DC link capacitors balancing problem in three-phase three-level bidirectional AC/DC converters operating with arbitrary power factor. Analytical expression for dynamics of partial DC link voltages difference is derived and studied in depth. The relation between zero-sequence component of modulation signals and neutral point current, tending to unbalance partial DC link voltages is explicitly established for arbitrary power factor values. Practical cases of restricted and unrestricted zero-sequence component of modulation signals are presented. Analytical predictions are shown to be fully supported by simulations based on both switching-cycle-averaged and full switched converter models. Experimental results obtained employing a 10kVA T-type converter prototype operating with restricted zero-sequence component of modulation signals under different power factor values are also given to further validate the presented methodology. [ABSTRACT FROM AUTHOR]

The μ10 gridded ion thruster, designed and developed at the Institute of Space and Astronautical Science, Japan, is used in the asteroid explorer Hayabusa2. In this propulsion system, the cathode is negatively biased with a power supply. The potential difference between the cathode and the system ground is regarded as an essential indicator of the cathode condition. In the operation of μ10 during the Hayabusa2 mission, it was found that the potential difference increased faster than that measured in a durability test on the ground. In this study, we performed a fault tree analysis of the on-orbit increase in the potential difference between the cathode and the system ground considering the total current balance (including electrons that flow back to the spacecraft). In addition, to understand the effect of the conductive surface around the thruster on the potential difference, we experimentally simulated the change in conductive area. It was found that the potential difference increased under a certain conductive surface condition. The results suggest that the on-orbit increase in the potential difference between the cathode and the system ground is caused by a loss of surface conductivity. • Analysis on the cause of the increase in cathode voltage observed in the orbit. • A floating potential experiment simulating the loss conductivity around the thruster. • The voltage increases as the conductive surface area around the thruster decrease. • Conductive surface has position-dependent electron collection profile. • Control by the cathode bias power supply lowers the coupling voltage. [ABSTRACT FROM AUTHOR]

Model predictive control (MPC) is an outstanding control method which can achieve superior dynamic response, nonlinear control and multi-objective collaborative control. However, because of unfixed switching frequency, the harmonic spectrum of the output current is dispersed, which would make it difficult to design the output filter. In this work, a double voltage vector model predictive control (DVV-MPC) algorithm for grid-connected cascade H-bridge (CHB) multilevel inverter is presented. The algorithm not only has the advantages of MPC but also produces fixed the switching frequency of the inverter. It is realized by a modulation stage with two adjacent voltage vectors in one switching cycle. And the duty cycle of the associated voltage level is obtained by minimizing an additional cost function. This method is suitable for the cascades of n cells inverter. For reducing the computation burden and eliminating the computation delay, adjacent regions prediction method and time-delay compensation method are applied to the inverter. Finally, in this paper, the proposed strategy is applied to a single-phase grid-connected 7-level CHB inverter. Simulation and experiment are executed to show the advantages of the proposed control algorithm in dynamic state and steady state. • A double voltage vector MPC strategy is proposed for n-level CHB inverters with fixed switching frequency. • The optimal vector is composed of two voltage vectors with different action times and magnitudes in one control cycle. • The proposed method is realized to facilitate the filter design and the current THD is further improved. [ABSTRACT FROM AUTHOR]

The clinical utility of the Apple Inc.® smartwatch in scenarios beyond detecting atrial fibrillation has been debated. Although the device has the capability to record electrocardiograms (ECG) and detect arrhythmias, voltage limitations hinder its accuracy in measuring real voltage when recording precordial leads. This limitation poses challenges for its clinical use in diagnosing ischemia and screening cardiomyopathies. This review aims to analyze the ECG recording capacity of the Apple Watch, investigate the reasons for voltage limitations, and explore alternative approaches for its use in these clinical scenarios. A comprehensive literature review was conducted to examine the ECG recording capacity of the Apple Watch and the limitations encountered when recording precordial leads. Data in CSV format files were analyzed to gain insights into the underlying causes of voltage limitations. The Apple Watch demonstrates effectiveness in detecting cardiac arrhythmias such as atrial fibrillation using photoplethysmography and ECG recording. However, voltage limitations during precordial lead recordings impede accurate voltage measurement, thereby limiting its clinical utility. Analysis of the data stored in the CSV files revealed that these voltage limitations are primarily attributed to the presentation format. Exploring alternative approaches for data processing could potentially overcome this challenge. This review highlights the potential for addressing voltage limitations through alternative data processing approaches. Further research is necessary to identify suitable alternatives that enable the Apple Watch to be effectively utilized in these clinical scenarios. • The Apple Watch has demonstrated the capability to record ECGs from a single lead and detect atrial fibrillation using photoplethysmography. • Strategically placing the smartwatch on body parts allows recording up to 9 leads, mimicking a standard ECG's morphology. • The device's format limits voltage in precordial leads, leading to inaccuracies and reducing its clinical utility. • This review analyzes Apple Watch's ECG recording capacity and CSV file utilization to explore and mitigate this limitations. [ABSTRACT FROM AUTHOR]

In recent years, the research on hydrovoltaic conversion has made rapid progress, showing potential prospect in the field of power generation. However, it still faces many issues, such as expensive, uncontrollable engineering, undetermined mechanism and difficulty in commercialization. To provide a low-cost, undemanding and practical strategy, the carbonized rice husk was first used to construct a biogenetic membrane device in this work, giving a sustaining hydrovoltaic voltage at ∼160 mV. Relevant studies that associated with mechanism and key factors for hydrovoltaic process were also implemented founded on different test conditions. It is proved that the fluids flow driven by evaporation and capillary effect is an essential prerequisite for hydrovoltaic conversion. The mechanism for generating electricity should be attributed to the streaming potential theory, which can provide an electric potential difference by selective transmission of ions owing to the Debye shielding effect. Based on this as-proposed theory, the controlling projects like improving pressure difference (ΔP) of fluid, ambient temperature and humidity, which generally enhance the hydrodynamic driving force and effective flowing area, logically demonstrate positive answers on hydrovoltaic performance. Moreover, in view of the super hydrophilicity of carbonized rice husk, this biogenetic membrane has demonstrated strong sensitivity on human breath monitoring with rapid response for every breath, which provides a potential way for the practical application of hydrovoltaic effect. [ABSTRACT FROM AUTHOR]

In this paper a new dc to ac Interconnected Cascaded Converter (ICC) is presented. The proposed ICC consists of several modular submodules of two switches and an inductor interconnecting two capacitors. Each submodule is controlled to keep the voltage on each capacitor as a slice of a sinewave. The output voltage of the converter, according to KVL, includes the sum of the voltages on the capacitor that represents a full pure sinewave. The sinusoidal output of the converter can be varied over a wider range. The proposed converter has the following advantages: sinusoidal output voltage with v/f control; absence of dv/dt related issues; compact size/weight/volume due to the use of wide band gap switching devices. The converter is modular in construction, employs high frequency L-C components and semiconductor switches can be stacked for voltage sharing. The proposed converter is a promising candidate for multiple applications such as high performance ac motor drives, microinverters and uninterruptible power supplies, carbon neutral logistics and electric vehicles. The paper details the operating modes, control aspects along with an illustrative design example for a three and eleven module converter. Experimental results on a laboratory prototype converter employing 600 V GaN devices are discussed. [ABSTRACT FROM AUTHOR]

In this study, the effect of La doping on the resistive switching properties of BiFeO 3 (BFO) is systematically discussed. It was found that La doping can not only inhibit the volatilization of Bi and thus diminish the intrinsic oxygen vacancy of BFO, but also improve the lattice symmetry of BFO for generating orthorhombic phase BFO. To confirm these microstructural changes and their relation to the resistive switching properties of BFO, the phase structures, chemical compositions, microstructures, energy band structures, and interfacial features of BFO with different La-doping concentrations are characterized. The resistances of BFO devices with different La doping concentrations also show significant differences, especially, the 15 at. % La-doping BFO device exhibits ultra-low operation voltage of only −0.15 V and good cycling consistency due to the integration of low oxygen vacancy concentrations and precipitation of the orthorhombic phase. The multiple effects of La doping on the resistive characteristics of BFO discussed in this paper provide a reference for the application of BFO in the field of resistive memories. [ABSTRACT FROM AUTHOR]

In this paper, a new framework for distributed switching control of parallel DC–DC buck converters is investigated, which represents voltage regulation and current sharing as two decoupled control design problems. The problem is described as a cascaded switched affine system with the new variables output voltage, total current, and current difference of the load, and by employing distributed min-projection switching technique, switching control signals are provided to achieve both voltage regulation and current sharing control objectives. Stability analysis based on relay control is carried out to guarantee the asymptotic stability of the error signals. Finally, the performance and effectiveness of the proposed control strategy are demonstrated by simulation studies as well as experiments conducted on a laboratory prototype. • The voltage regulation and current sharing control problems are studied for parallel DC–DC buck converters. • The system is modeled as interconnected switched affine system resulting in multi-objective switching control design. • Design procedure of the Theorems are based on the relay control and solving some LMIs. [ABSTRACT FROM AUTHOR]

To optimize the performance of the Collinear Resonance Ionization Spectroscopy (CRIS) experiment at CERN-ISOLDE, technical upgrades are continuously introduced, aiming to enhance its sensitivity, precision, stability, and efficiency. Recently, a voltage-scanning setup was developed and commissioned at CRIS, which improved the scanning speed by a factor of three as compared to the current laser-frequency scanning approach. This leads to faster measurements of the hyperfine structure for systems with high yields (more than a few thousand ions per second). Additionally, several beamline sections have been redesigned and manufactured, including a new field-ionization unit, an electrostatic bend with a larger deflection angle, and improved ion optics. The beamline upgrades are expected to yield an improvement of at least a factor of 5 in the signal-to-noise ratio by avoiding the use of high-power lasers (which yield non-resonantly produced ions) and providing time-of-flight separation between the resonant ions and the collisional background. [ABSTRACT FROM AUTHOR]

The voltage violation in distribution networks may occur frequently due to the rising integration of flexible demands and supplies. In this paper, the reactive power of the inverter-based distributed generator (DG) and OLTC tap position are adjusted for voltage regulation in coordinated manner. Firstly, the reactive power adjustment for the voltage regulation has been carried out by use of the DG reactive power capacity. Afterwards, the tap position of the OLTC has been changed to regulate the bus voltage that has a voltage violation problem in the case of insufficient reactive power capacity of the DG inverter. The value of the distributed generator reactive power output that regulates the voltage on the bus that has a voltage violation is found with proposed curve-fitting method and tested with the Grid Search, Artificial Bee Colony methods. The proposed method derives mathematical expressions between DG reactive power output and bus voltages as quadratic equations by curve-fitting technique. Moreover, addition to inherent upper and lower reactive power limits of the DG inverter, they are determined by the proposed curve-fitting based technique while considering voltage constraints on all buses. Proposed method is much faster than other two methods because of its plain structure and gives adequate accurate results. [ABSTRACT FROM AUTHOR]

The reliability of electrical systems is a critical operational characteristic for distribution companies. On the other hand, they pay great attention on reducing losses in primary and secondary distribution lines. In this article, a modified Jellyfish Search (MJFS) algorithm is presented for handling Optimal Network reconfiguration (ONR) in Medium Voltage Distribution Feeders (MVDFs). An ONR formulation is proposed for reliability enhancement and power loss reduction in a multi-objective model where three reliability measures are incorporated which are total energy not supplied (TENS), system average interruption unavailability index (SAIUI) and system average interruption frequency index (SAIFI). The proposed MJFS expands on the JFS searching benefits by introducing a quasi-oppositional-based learning and social neighborhood strategies. Also, a proposed bus-line feeding matrix (BLFM) is incorporated to develop the MJFS. Through the BLFM, each distribution line is simulated as an outage and the regarding distribution nodes which are not supplied is estimated. The simulation results are performed on a large-scale IEEE MVFD of 137-bus which derive significant improvements of the proposed MJFS over the standard JFS algorithm. Considering the proposed multi-objective model, the proposed MJFS achieves great reduction in power losses, TENS, SAIUI and SAIFI with 44.42, 30.57, 30.78 and 23.92 %, respectively compared to the initial case. Also, versus the standard JFS, grey wolf optimizer, tuna swarm optimization, equilibrium optimizer and tunicate swarm optimization, the proposed MJFS acquires great reduction in the standard deviation with improvement of 2.5, 92.51, 10.67, 91.53 and 96.51%, respectively. [ABSTRACT FROM AUTHOR]

Direct Torque Control (DTC) of Induction Motors (IMs) is popular in motor drive applications because of its robust and simple control structure. The IM winding can be controlled on both sides using dual inverter technique which more effective for Electric Vehicle (EV) with a greater number of voltage vectors. However, the battery performance of the dual inverter will deteriorate unevenly on both sides, resulting in fluctuating voltages for the EV system. This will lead to the generation of distorted stator currents and a significant droop in the stator flux, which in turn can increase the total harmonic distortion (THD) in the system. Additionally, the performance of torque may not be able to regulate effectively. This paper examines the effect of unstable voltage on voltage vector mapping performance with tilted angles and proposes new sector definitions based on voltage ratio conditions. Moreover, the proposed sector for each predefined voltage ratio is tested under three-speed conditions. The proposed technique effectiveness is validated through hardware experiments using a dSPACE 1104 controller and retuning the stator current for proper waveform. This approach improves the stator current waveform, improves stator flux droop, enhances torque regulation and minimizes the THD in the DTC system. [ABSTRACT FROM AUTHOR]