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Power sources play an important role in the characteristics and the applications of the electrothermal (ET) plasma as an edge localized mode (ELM) heat flux simulator. A repetitive high current ET plasma source with the capability of working at a 10 Hz repetition rate and peak current 7.5 kA is presented in this paper. By controlling the sequence of discharge of ten pulse power modules, a repetitive high heat flux plasma jet can be generated. A two-stage capillary structure is presented, and its repetitive trigger driving circuit based on surface flashover ignition is designed to achieve reliable and repetitive discharge. The topology of the inductive and capacitive (LC) series resonant circuit is applied to the charging system of the pulsed power source. The charging current is limited to 500 A with a charging time of 3.5 ms, and the ratio of the charging voltage to the operating voltage is 1.85. A diode and a power resistor in series are used to suppress the negative overvoltage, which is helpful to increase the thyristors’ operating reliability. Using the designed repetitive ET plasma source, the characteristics of the ET plasma jet are investigated by measuring the voltages and currents and by obtaining images of the discharges. Experimental results show that the repetitive ET plasma generator can be used as an appropriate way to simulate the ELM-like heat flux plasma.

Low voltage circuit breaker is a crucial component for protecting power distribution system. The breaking capability is the key parameter of low voltage circuit breaker. Outgassing material is commonly used to improve the breaking capability in low voltage circuit breakers. Therefore, the evaluation method of outgassing characteristic of outgassing material is critical. This paper focus on the experimental study on outgassing properties evaluation of polymers. The detachable experimental prototype is designed and produced. In order to ensure that the arc burns in the middle of the quenching chamber, the electrode is designed in a triangular shape. Outgassing material is arranged around the arc quenching chamber. The copper wire is used to ignite arc in experiment. The arc voltage, arc current, pressure of quenching chamber, ablation mass of outgassing material, insulation resistance after arcing are obtained. The effects of different polymers on arc characteristic at various current levels are comparatively analyzed. The metrics for evaluating the properties of polymers are proposed. It provides a theoretical basis for the selection of outgassing polymers.

Overheating is one of the key factors affecting the normal service life of switch cabinets. Therefore, it is of great significance to find out methods to reduce the temperature rise of the switch cabinet. In this paper, based on a 400V low-voltage switchgear, a three-dimensional simulation model is established using the electromagnetic-thermal-fluid multi-physics coupling method. Under the conditions of simulating natural convection, considering eddy current effects, proximity effects, and skin effects, heat transfer methods such as thermal conduction, thermal convection, and thermal radiation are comprehensively used to calculate and analyze the thermal distribution characteristics of the distribution cabinet shells and three-phase current-carrying conductors. Moreover, a temperature-rise experiment is performed to verify the feasibility and accuracy of the electromagnetic-thermal-fluid multi-physics coupling method and the accuracy and effectiveness of the calculation model under the current simulation conditions. In addition, in order to reduce the temperature rise of the cabinet, A strategy for optimizing the switchgear is proposed, and the heat distribution characteristics of the optimized model is calculated using the multi-physics coupling method. The results show that the temperature rise of the switch cabinets of the scheme has been reduced in different degrees, which effectively solves the overheating problem of the switch cabinet.

With the rapid development of dc system, the residual current in dc system has become an urgent problem to be solved. However, the type B residual current devices (RCD) for ac systems could not be directly used in dc systems. The ac residual current caused by distributed capacitance and the rectifier seriously interferes with the accurate detection of the dc residual current. A detection simulation model of dc residual current based on magnetic modulation was established. The authors also proposed detection algorithms based on Kalman filter and moving average filter separately. The experimental results showed that the proposed model and detection algorithms were effective. They could detect the residual current in the dc system under ac interferences.

For intensely burning photovoltaic (PV) series arc faults without strong noise interferences, their time-frequency features are easily to be discovered. However, various PV systems would generate noise interferences to the arc fault signal, causing difficulties to distinguish the arc fault and normal states. To solve this kind of problem, new measurements should be taken to acquire obvious arc fault features even from the weak arc fault electrical signals.In this paper, weak PV series arc fault electrical signals are acquired from the designed experimental setup with different load types firstly. Then it is found that the performance of arc fault features are not that satisfying in higher frequency bands after directly applying the existing Db9 based wavelet transform, causing the arc fault detection problem. Next, arc fault features are enhanced in most frequency bands by conducting the proposed Rbio3.1 based wavelet transform. Finally, the stochastic resonance (SR) method is proposed to further enhance Rbio3.1-based arc fault feature. The compared results prove that the combination between SR method and Rbio3.1 wavelet transform show the effective feature enhancement ability facing weak PV series arc fault electrical signals with different inverters and resistors.

In recent years, the perfluoroketone (C 5 F 100 ) has drawn much attention as one of the potential environmental-friendly gas to substitute SF6 in power industry. C 5 F 100 performs well in insulation with the low GWP of less than 1. In the gas-insulated systems, the insulation gases will have inevitable and direct contact with different solid surfaces. The $\alpha$ -Al 2 O 3 -filled epoxy resin and Al 2 O 3 ceramics always be used as insulation materials in GIS and GIL. In this paper, the interaction between C 5 F 10 O and $\alpha$ -aluminum oxide under electric field was investigated by density functional theory (DFT) calculations. Based on several adsorption structures, an electric field was applied in Z direction, simulating the working condition of electrical apparatuses in practical engineering. The adsorption energy and charge transfer have been calculated, and it has been confirmed that the interaction of CsF 10 O on $\alpha$ -Al 2 O 3 (0001) surface belongs to chemisorption, and the external E-field have little impacts on the adsorption properties in practical engineering, which can provide basics for further study on compatibility of the insulated gas-solid systems and guidance for the stable operation of eco-friendly apparatus using C 5 F 10 O.

In recent years, a new electromagnetic repulsion mechanism (ERM) has been applied in high voltage vacuum circuit breakers (HVVCBs). However, the current research on ERM mainly focuses on the design and improvement of mechanical structures, ignoring the aspect of their fault diagnosis. In order to determine the fault types occurred in ERM, a fault diagnosis method based on improved S transform (IST) and support vector machine (SVM) is proposed. Firstly, the vibration signals are obtained at two different positions of the HVVCB with ERM during the operating process. Then, the IST is used to conduct the time-frequency analysis on the vibration signals. The feature is extracted based on the energy entropy from the normalized energy. Finally, the grid search (GS) and particle swarm optimization (PSO) algorithms are adopted to realize parameters optimization of support vector machine (SVM). Moreover, the other two features and three classifiers are used to verify the effectiveness of IST. The results show that the proposed method is suitable for HVVCB mechanical fault diagnosis.

SF 6 gas is widely used in power equipment for its excellent arc extinguishing and insulation properties. However, SF 6 is a strong greenhouse effect gas with a global warming potential (GWP) of 23,500 times that of CO 2 . Therefore, the Kyoto Protocol signed in 1997 has included SF 6 in one of the six greenhouse gases which are restricted for use. Nowadays, finding an environmentally friendly alternative gas for SF 6 is a hot issue in the world. The research on SF 6 environmental alternative gas has made great progress these years. C5F 10 O is considered the most likely gas to replace SF 6 in the near future. Although C 5 F 10 Ohas a good arc extinguishing property in general, the arc extinguishing mechanism of it in the load switch is not clear. Because arc extinguishing is a complex physical and chemical process involving the interaction of gas flow fields, electromagnetic fields, and ablation the nozzle materials. In this paper, by combining the computational fluid dynamics (CFD) analysis and the Mayr arc model the interruption processes for a load switch filled with 5%C 4 F 7 N/CO 2 and 5%C 5 F 10 O/CO 2 at 0.135 MPa, as well as pure SF6 and CO 2 at 0.135 MPa, are investigated. The time constant θ and arc cooling coefficient $Q$ at the current zero point is calculated based on the Mayr equation. In the end, the critical values of the rising rate of the recovery voltage (RRRV) are obtained. These parameters are the most important issues to determine whether breaking success or not. Through the analysis of the post arc medium recovery, the arc extinguishing performance of different gas medium can be theoretically and quantitatively evaluated. It can provide a sufficient theoretical basis to enhance the arc extinguishing ability of the load switch through the CFD analysis.

SF 6 is widely used in high-voltage electrical equipment due to its excellent insulation and arc quenching ability. However, SF 6 is a greenhouse gas with a very high global warming potential (GWP), about 23,500 times than that of CO 2 . Recently, many studies have demonstrated that C 4 F 7 N has excellent insulation properties and environmental characteristics. So it is a promising alternative gas to SF 6 . Researchers have made some progress towards understanding the decomposition characteristics of C 4 F 7 N under overheating condition. However, there are few studies of C 4 F 7 N decomposition characteristics under partial discharge from theory and experiment aspects. In this paper, the partial discharge experiment platform is established and the calculation model is applied to calculate the decomposition pathways and main products under partial discharge. The relevant results may provide the reference for electrical application.

In this paper, the efficiency of a conventional cross-coupled gate CMOS bridge rectifier used in MEMS (microelectromechanical system) piezoelectric energy harvesters is investigated. The MOSFET threshold voltage is varied between 10 mV and 800 mV to evaluate the performance of the circuit for various threshold voltage levels. The circuit is simulated using the 130 nm CMOS technology process for each MOSFET to generate performance metrics for the rectifier. The results are evaluated for optimal load resistance, and it is confirmed that a lower threshold voltage results in significant improvements to the efficiency of the rectifier at lower input voltage amplitudes, with up to 62% at 0.5 V input amplitude when a smoothing capacitor is placed across the load.

This study focused on exploring various in vitro to in vivo extrapolation (IVIVE) approaches with the primary goal of improving human hepatic clearance (CL) prediction for OATP substrates. To that effect, the impact of albumin-mediated uptake in human hepatocytes was investigated. In vitro hepatic uptake assay using suspended human hepatocytes was performed with 16 selected OATP substrates to determine the uptake CL in the absence and presence of 4% BSA and unbound hepatocyte to media partition coefficient (Kpuu). Substantial enhancement of the unbound uptake CL (PSu,inf) was observed in the presence of 4% BSA, demonstrating "albumin-mediated" uptake. Prediction of human hepatic CL was performed using two non-traditional IVIVE approaches: initial uptake CL (PSu,inf) and intrinsic metabolic CL (CLint,met) corrected by Kpuu based on extended clearance concept. Compared to traditional IVIVE using CLint,met only, the two tested IVIVE approaches significantly improved the prediction of human hepatic CL. Particularly, direct extrapolation from PSu,inf (+BSA) showed the most robust correlation with in vivo human hepatic CL for all 16 compounds with bias of 1.9-2.0 for two lots of human hepatocytes, respectively. In addition, PSu,inf (+BSA) and Kpuu were also determined in suspended cynomolgus monkey hepatocytes. Prediction of monkey hepatic CL was improved by both approaches, although with more bias compared to human. These results suggested supplementing 4% BSA in human hepatocyte uptake assay provides a useful tool to characterize hepatic uptake CL for OATP substrates, enabling more accurate human CL prediction without any empirical scaling factor (ESF).

Perfluoronitriles (PFN) and their mixtures have garnered much attention as a great potential SF 6 -substitute gas, owing to their excellent dielectric strengths and minimal impacts on the environment. The dielectric properties of C4-PFN/CO 2 and SF 6 /N 2 mixtures are investigated and compared by experiments and calculations, with taking into account the limitations of saturated vapor pressure on the mixed ratio at certain ambient temperatures. The saturated vapor pressures of these two mixtures are determined by combining the Antoine Equation and the basic law of vapor liquid equilibrium. Then, the 50% breakdown voltages V 50% of the C4-PFN/CO 2 and SF 6 /N 2 mixtures are determined by tests with up-and-down method, and the values of E/p are deduced. Finally, the dielectric properties of these two mixtures are analyzed by combining the saturated vapor pressure characteristics and the breakdown electric field strengths. The results show that a proper choice of the mixed ratio and gas pressure of the C4-PFN/CO 2 mixture can provide a stronger DS than the SF 6 /N 2 mixture and pure SF 6 . This indicates a great potential of the C4-PFN/CO 2 mixture as a SF 6 -substitute gas for high voltage apparatus.

Air circuit breaker (ACB) is widely used in power distribution system. The movable contact of ACB consists of multiple parallel contacts and the arc will be ignited between arcing contact and static contact when the short-circuit current appears. This paper focuses on the arc evolution process at various currents in multiple parallel contact systems. A 3-D magnetohydrodynamic model of a multiple parallel contact structures is developed. In this model, the anode consists to five parallel contacts, and they are separated by insulation material. The near-electrode layer with a nonlinear voltage-current density characteristic is modeled to describe the near-electrode voltage drop, and the difference between near-anode and near-cathode layers is considered. The magnetic vector potential approach is adopted to calculate the time-varying electromagnetic field produced by the current loop. The arc evolution processes at various currents are analyzed by current density and arc voltage. It is noted that the anode arc root appears on multiple contacts with the increase of current. The arc evolution process mainly depends on the arc resistance characteristic.

The air circuit breaker used for permanent magnet wind power generation systems should switch OFF the short-circuit current of variable frequencies. This paper focuses on the influence of frequency on the behavior of air arc. A 3-D magnetohydrodynamic (MHD) model of air arc plasma was developed to investigate the arc motion process at variable frequencies. In this model, the eddy currents in the whole calculation domains including the electrodes, the splitter plate, and the arc column were considered, and the magnetic vector potential approach was adopted to calculate the electromagnetic field produced by the current loop. A thin layer of elements with a nonlinear voltage–current density characteristic surrounding the splitter plate was employed to represent the formation of new arc roots and electrodes voltage drop. Based on this model, the evolutions of arc voltage, temperature, normalized time, and current density were obtained and compared among variable frequencies. The simulation results reveal that the normalized time, the eddy current density peak in splitter plate, and the arc voltage peak increase at a higher frequency.

In recent years, C 4 F 7 N has been highly concerned due to its excellent dielectric performance and arcquenching ability. As a potential alternative to SF 6 , the decomposition characteristics of C 4 F 7 N will directly affect its application prospects. However, there are few studies on the decomposition characteristics of C 4 F 7 N mixed gas. Therefore, we conducted AC discharge breakdown experiment and partial discharge experiment on C 4 F 7 N-CO 2 mixed gas, and analyzed the gas decomposition by-products of C 4 F 7 N-CO 2 mixed gas qualitatively and quantitatively by using gas chromatography-mass spectrometry (GC/MS). The results show that the major decomposition by-products under AC discharge breakdown are CO, CF 4 , C 2 F 4 , C 2 F 6 , C 3 F 8 , CF 3 -CN, C 3 F 6 , C 4 F 6 , C 4 F 10 , C 2 F 5 -CN, C 2 N 2 , HCN, C 2 F 3 CN. Under partial discharge, the major decomposition byproducts are CO, CF 4 , C 3 F 8 , CF 3 -CN, C 3 F 6 , C 4 F 10 , C 2 F 5 -CN, C 2 N 2 , HCN, C 2 F 3 -CN. Compared with the partial discharge process, AC discharge breakdown produces more types of decomposition by-products. Besides, AC breakdown tends to produce smaller molecular by-products, while partial discharge tends to produce larger molecular by-products.

SF6 has been employed as insulation and arc-quenching medium in high voltage apparatus since the 1960s. However, due to the high global warming potential (GWP) of SF6 gas, the alternative to SF6 is required. R12 and R134 gases offer good dielectric properties to be good replacements of SF6 as insulation medium considering the environmental concerns. In order to further investigate the ionization processes in those gases, the electron-impact ionization cross sections are calculated by Deutsch-Mark (DM) and its modified methods. The molecular structures and the molecular orbital compositions of R12 and R134 were determined by ab initio calculation. The results give important reference for the two SF6 substitute gases.

Electrical explosion of wires has caused the attention of researchers because of its rich physical phenomena and plenty applications. Microsecond electrical explosion of Cu wires in air under various parameters is conducted, and diverse discharge waveforms are displayed and analyzed. By statistically summarizing the experimental results, experimental parameter selection suggestions for specific applications are given. In addition, the experimental results show that the average axial breakdown field strength is greatly changed with the breakdown time. It drops linearly from ~13 to ~3 kV/cm when breakdown time varies from 2 to $6~\mu \text{s}$ , it keeps at a relatively low value about 1 kV/cm when the breakdown occurred after $8~\mu \text{s}$ . The effect of current density on the rising edge of the resistivity curve is confirmed by the experimental results. Based on the correlation between the breakdown time and breakdown field strength and the correlation between the maximum current density and specific action when resistivity reaches 200 $\mu \Omega \cdot \text {cm}$ , the specific-action model is improved empirically. The proposed “two-stage” model better reflects the actual physical process and has higher accuracy and a wider scope of application.

Short-time withstanding current is a key parameter of air circuit breakers. Due to the structure of multiple parallel contacts, the outer movable conductors tilt and slide seriously when withstanding the large short-circuit current. This paper is aimed to investigate the contact behavior of the tilted contact. A new designed experimental setup to measure the minimum repulsion current and the contact resistance of the tilted contact is developed. Contact force and tilt angle can also be measured and adjusted. Based on the measured results and the impression marks of the tilted contact, it is concluded that the repulsion force and the contact resistance are increased seriously when the contact is tilted. During the contact tilting process, the contact type is changed from the line contact to the point contact and the contact center is offset to the edge of the movable contact. In addition, with the help of contact bridge model, it is also found that the contact type transition plays a dominant role on the increase of the repulsion force and contact resistance.

Perfluoroketone C5F10O is considered as a potential SF6 alternative. The global warming potential of C5F10O is extremely low and even close to that of air. We investigated the electrical insulation properties of the C5F10O by pulsed Townsend experiment. The rate coefficients of ionization, attachment, and effective ionization, as well as the electron drift velocity and the longitudinal electron diffusion coefficient in pure C5F10O were obtained. We conclude that the density-reduced critical electric field of pure C5F10O is (768 ± 5)Td and ion kinetics are not exist or negligible in C5F10O. Furthermore, the swarm parameters of C5F10O/CO2 and C5F10O/Air mixtures with C5F10O percentage up to 30% were measured in a wide E/N-range. C5F10O has good synergism with both CO2 and dry air and air behaves better. The synergistic effect coefficients were also calculated. To have the same (E/N)crit as pure SF6, the mixing ratio of C5F10O should be 30% in the mixture with CO2 and 26% in the mixture with dry air. The obtained electron swarm parameters in this paper provide a supplement for the fundamental data set of these novel gases, and also lay the foundation for fluid model simulations of gas discharge.

The behavior of the transient heat flux produced by a three-electrode capillary discharge generator working at a repetitive mode is presented in this paper. The radial distribution profiles of plasma temperature, electron density, and thermal load are obtained by the optical emission spectrometry and correction algorithm. Experiments with different capillary diameters and charging voltages are carried out, and the relation between the discharge characteristics and the geometry parameters of the capillary is measured. A maximum transient thermal load of 1.42 GW·m−2 is obtained with 10 Hz, which can meet the thermal load amplitude requirement of Type-I edge localized mode heat flux in the ITER-like Tokamak.

The Chinese Loess Plateau (CLP) in North China is an important terrestrial archive that witnessed the environmental changes and mammal and early human evolution in Asia over the past 2.6 Ma. Establishing precise ages for the Pleistocene faunas on the CLP is critical for better understanding of these environmental, biological, and archaeological issues. Here we report a new magnetostratigraphic record that places age constraints on the Linyi Fauna on the southeastern CLP. Our investigated 170-m-thick Linyi section mainly consists of two portions: (1) an overlying eolian Quaternary loess-paleosol sequence and (2) underlying fluvial-lacustrine sand and silty clay. Paleomagnetic results suggest that the composite section records the Brunhes chron, Jaramillo and Olduvai subchrons, and successive reverse polarity portions of the intervening Matuyama chron. The Linyi Fauna is located between Jaramillo and Olduvai subchrons in the fluvial-lacustrine interval, with an estimated age of ~1.5–1.6 Ma. Combining previously dated faunas, we establish a Pleistocene magnetochronology spanning from 2.54 to 0.65 Ma for the faunas on the CLP.

Measurement of the magnetic field distribution in Z-pinch experiments remains an ongoing challenge. We present a method of measuring the radial distribution of the magnetic field around a copper rod using Zeeman splitting of sodium (Na) emission lines, in which an Na layer is formed by the laser ablation of NaCl crystals on a load surface. The load consists of a copper rod of 2 mm diameter and is pre-covered on its surface by the NaCl crystals. An 8 ns pulsed laser with an energy of 1 J and wavelength of 532 nm is focused on the crystals. The Na plasma is produced and expands from the surface of the copper rod into a vacuum. After applying a pulsed current with a peak value of 375 kA to the load, the Na 3s-3p doublet displays significant Zeeman splitting patterns. The self-luminosity of the Na plasma is recorded by a spectrometer coupled with an intensified charge-coupled device camera from an end-on view to eliminate the effects of different observing angles and Doppler shifts. We determine the magnetic field by fitting the measured spectra with the calculated results of the Voigt profile. The measurable range of radial position is 5-7 mm, and the corresponding magnetic field is 5-15 T. The averaged error of curve fitting is less than 12%.

This paper aims at providing a reliable algorithm to identify photovoltaic (PV) series arc faults regardless of complex fault-like interferences. Through conducting various arc fault experiments with different PV current levels, arc gap lengths, and load types, PV series arc fault features have been understood comprehensively. To avoid unwanted nuisance tripping, fault-like conditions are analyzed to confirm the unique arc fault features. Based on the loop current signature, a greater unstable fluctuation in the time domain and extra arc noises in the time-frequency domain are chosen as identification features. By quantificational evaluations, optimal detection variables with the Hamming window and the proper time resolution have been established to achieve the best identification results. By building fusion coefficients, two variables are arithmetically fused to achieve the arc fault discovery. The algorithm could also classify fault-like into normal and adjust the threshold value dynamically to fit different normal current levels. Its validity has been verified by experimental results on the simulated platform.

Paralleled high-voltage SF6 circuit breakers with a highly coupled split reactor (HCSR) could realize the function of automatic current-sharing and current-limiting. Aiming at investigating the arc characteristics of paralleled SF6 circuit breakers with an HCSR, the single-phase tests for the paralleled high-voltage SF6 circuit breakers with an HCSR were carried out, including the opening and closing–opening operations. The influence of the capacitor paralleled to one of the breaks was studied. A mathematical model was developed for the paralleled high-voltage SF6 circuit breakers with an HCSR by coupling the equivalent circuit equations into the magnetohydrodynamic (MHD) arc model through the embedded codes, laying the foundation for the further research. The variation of the short-circuit currents in the branches during the breaking process was analyzed in detail. The current-sharing and current-limiting effects are quite satisfying. The temperature distribution of both arc chambers was presented. The calculated results were in agreement with the experimental results to some extent.

c-C 4 F 8 and CF 3 I and their mixtures have garnered much attention as possible substitutes for SF 6 due to their excellent electrical strength and minimal impact on the environment. Taking into account the limitations of saturated vapor pressure on the mixed ratio, the insulation performances of c-C 4 F 8 -N 2 and CF 3 I-N 2 mixtures are numerically investigated and compared in this paper. The saturated vapor pressures of c-C 4 F 8 -N 2 and CF 3 I-N 2 mixtures are determined by combining the Antoine equation and the basic law of vapor liquid equilibrium. Then, the critical electric-field strengths of these mixtures are calculated by Boltzmann analysis. By analyzing the saturated vapor pressure characteristic and critical electric-field strength, it is found that the CF 3 I-N 2 mixture shows greater potential than the c-C 4 -F 8 -N 2 mixture as an insulating medium, from the view of electrical strength. Under a gas temperature of -10°C, the CF 3 I-N 2 mixture at CF 3 I concentrations of 20% and 30% can be used under 0.79 MPa and 0.53 MPa, and the electrical strength of the CF 3 I-N 2 mixtures can approach 1.02 and 0.75 times that of pure SF6 at 0.5 MPa, respectively.

Ubiquitination is one of the fundamental post-translational modifications of proteins with ubiquitin, a conserved 76-amino acid protein present in eukaryotes, which is catalyzed by ubiquitin ligase. Compared with humans, the number of ubiquitin ligase genes is nearly double in plant species such as Arabidopsis and rice, suggesting that this enzyme plays critical roles in many aspects of plant growth, including development and abiotic and biotic environmental stress responses. In addition to its fundamental activities in eukaryotic cells, ubiquitin signaling mediates plant specific cellular functions, including phytohormone response, seed and fruit development, and biotic and abiotic stress responses. The ATL family is a RING-H2 type ubiquitin ligase widely conserved in plant species. We previously showed that the plant specific ubiquitin ligase ATL31 regulates the carbon/nitrogen-nutrient response and pathogen resistance in Arabidopsis, and we identified and characterized the basic biochemical function of an ATL31 homologue in tomato plants (Solanum lycopersicum L.). This protein, called SlATL31, may act as a ubiquitin ligase in tomato fruit. The tomato is a major crop plant and a model system for fleshy fruit development. This review provides an overview of the ubiquitin ligases and related enzymes, and highlights the ubiquitin ligase ATL family in tomato plants.

CO2 attracts a lot of attention of researchers as a possible substitute for SF6. The arc interruption capabilities of SF6-CO2 mixtures for different mixed ratios are investigated in this paper by carrying out tests with a 126 kV puffer gas circuit breaker prototype and calculations. Based on the measured arc voltage and current around current zero, the post-arc current characteristics and the thermal interruption properties are investigated for SF6-CO2 mixtures under different rise rate of the recovery voltage RRRV and di/dt before current zero. It is found that the interruption performance of SF6-CO2 increases greatly with increasing SF6 concentration, and the critical RRRV and di/dt before current zero of SF6-CO2 mixtures for SF6 content of 0, 20 and 50% are about 39, 45 and 70% of that of SF6 respectively, at the short-circuit current of 10 kA. The pressure increment at current zero is found to have a great effect on the interruption of the short-circuit current. In addition, the pressure buildup in CO2 is much lower than that in SF6 for both no-load and loaded operations.

Direct current (DC) miniature circuit breaker (MCB) is a crucial component for controlling and protecting the DC power system, especially in photovoltaic power generation system. In this paper, experiments under various current are carried out in different structures of DC MCB. Except arc current waveforms, the arc images during the interruption process are recorded by CCD. The interruption characteristics are analyzed. Also, a 2-D magneto-hydro-dynamic (MHD) model for the relevant MCB is developed. Based on the model, the effects of arc current, arc quenching chamber on the arc evolution process are analyzed. The experimental phenomena are well explained based on the simulation results. It is showed that the MCB with tilting contact has better breaking capacity due to the airflow acceleration effect of tilting contact, and the developed model could be used to optimize the design of the arc quenching chamber and contact system of DC MCB.

Without zero-crossings, dc series arc faults result in much more serious safety threats. As the dc voltage level rises and the system capacity increases, series arc faults appear in dc systems more frequently. To eliminate their damages, specific arc fault circuit interrupters (AFCI) should be developed. In this paper, two kinds of dc systems are considered in the designed experimental setup. Firstly, a dc simulated source with the ac-dc-dc structure is connected to a resistor. This source could act as a constant voltage or photovoltaic (PV) source by operating in different U-I output modes. Then a real PV array outputting the nonlinear U-I output curve is also conducted as a comparison. Next, a simple detection algorithm is proposed based on the established time-domain detection variable. Finally, this series arc fault detection algorithm is implemented using a digital signal processing (DSP) chip. The performance of this hardware behaves satisfying under various system transitions and multiple arc fault conditions with diverse operation points and current levels.

The erosion of electrode plays a crucial role in the reliability and life of low-voltage circuit breaker. Therefore, developing a valid erosion model for a range of current is important. In this paper, the arc-electrode unified model is established to determine mass loss under direct current air arc. This model includes two types of electrode material erosion: vaporization and sputter erosion. A two-dimensional magnetic hydrodynamics (MHD) model is built. In this model, the molten pool and arc are combined together. And the energy balance on the interface between electrode and arc is considered. The erosion model is established on the basis of the molten pool model. The vaporization flux caused by concentration gradient is calculated using the Langmuir formula when the surface temperature of molten pool is lower than its boiling point. The vaporization rate caused by pressure gradient is bigger than it caused by concentration gradient. The vaporization rate caused by pressure gradient is calculated by the fundamental principles of gas dynamics. The sputter rate is obtained based on statistical methods. The influence of electrode gap on the erosion is also carried out. The simulation results are compared with the experimental results in order to verify the accuracy and validity of the simulation model in the current simulation conditions.

Air circuit breaker (ACB) is widely used in power distribution system. The movable contact of ACB consist of multiple parallel contacts and the arc will be ignited when the short-circuit current appears. This paper focuses on the arc motion process in multiple parallel contacts system. A 3-D magneto-hydro-dynamic (MHD) model of multiple parallel contacts system is built. In this model, the nonlinear B-H curve of splitter plate is used in calculation. The magnetic vector potential approach is adopted to calculate the time-varying electromagnetic field produced by the current loop. The difference of voltage drop between near-anode and near-cathode is considered. In addition, the interaction among multiple parallel contacts is included in numerical simulation. Based on this calculation, the arc voltage, temperature and current density were obtained. The arc motion process is analyzed by current density and temperature. The simulation results show that the anode arc root will appears on multiple contacts with the increase of current. The upper arc moves faster than low arc after the arc column is divided by the splitter plate.

DC microgrids have the higher efficiency, higher flexibility, and lower cost than ac networks due to the fewer conversion stages. However, the protection of dc microgrids is still challenging because the limited ac protection technologies could be directly migrated to the dc system. For the sake of the human and equipment safety, the arc fault protection technology is one of urgently concerned aspects. In dc microgrids, arc electrical characterizations would be inevitably interfered by switching noises and higher system electric levels, making the arc fault detection more challenging.In this paper, dc series arc faults under the background of different switching noise interferences are conducted through the designed experimental platform firstly. Having analyzing arc faults with the single and multiple switching noise interference sources based on the signal separation method, the influence of switching noises on arc electrical characterizations is discussed. For arc faults with these inference factors, the existing arc fault features used in the resistive system indicate some limitations, leading to new arc fault detection difficulties. Finally, corresponding measures are taken to give the larger arc fault time discovery pulse and better separated arc fault states. The enlarged arc fault differences are of great benefit to improve the detection effectiveness in these complicated scenes.

The formation of precursor plasma and ablation dynamics of Al thin liner explosion are investigated in this manuscript. The size of 12 mm in diameter, 10 μm in thickness Al liners are exploded on the Qin-1 facility (about 450 ns, 450 kA). An axial laser shadowgraphy and interferometry platform is set up to observe the plasma dynamics inside the liner. To solve the problem that the inside plasma density of the liner cannot be absolutely calibrated due to the lack of a zero plasma density area, we have established a CW laser interference system using a streak camera which can trace the interference lines over time. Low-density (10−7−10−6 g cm−3) precursor plasma is generated from the interior wall and flows towards the center with a velocity of about 150–200 km s−1, thus forming a column with high electron density by accumulation. Simultaneously, a high-density plasma layer flows toward the center at about 10 km s−1. The electron density of the central plasma column rises up rapidly after the precursor reaches the center and achieves 2.5 × 1018 cm−3 at 280 ns after the current starts. To fully understand the process, we have used the resistive magnetohydrodynamic code FLASH to realize a simulation to study interior precursor dynamics. We compared these simulation results with our experiments. Finally, we measured the voltage for the whole process and derived the inductance change and effective current radius. We compared the simulated current density distribution with the experimental result which proves that a considerable amount of current flows through the center plasma column, making the effective radius of current become smaller over time.

This paper presents the design and test of a gas-insulated linear transformer driver (LTD) cavity aimed at the Z-pinch experimental device CZ-34. The LTD cavity has a diameter of 2290 mm and a height of 346 mm. It consists of 23 main bricks and 1 trigger brick. Each main brick is comprised of two 100 nF capacitors connected electrically in series with a field-distortion gas switch. The trigger brick is comprised of two 50 nF capacitors connected in series with a compact multi-gap gas switch. All bricks are placed in the cavity filled with compressed SF6 and are pluggable like drawers. The trigger pulse generated by the trigger brick passes through an azimuthal transmission line to the trigger ring and makes the main bricks discharge synchronously. The LTD cavity can deliver ∼1 MA current pulse with a rise time of 115 ns to 0.08 Ω liquid resistance load when the charging voltage is ±100 kV, which is in good agreement with the circuit simulation results. Experimental results demonstrate the successful application of using gas insulation and pluggable bricks. The technical feasibility of the charging configuration, triggering method, and isolation resistors is verified. There is little difference in output performance as return-current rods replaced the outside metal cylinder, which provides a new path for the design of LTD cavities in series.

Remote and on-line measurement of chromium on structural steel surface in nuclear power plants is critical for protection against fluid accelerated corrosion. To improve the insufficient sensitivity of fiber-optic laser-induced breakdown spectroscopy toward trace element detection, a dual-pulse spectral enhancement system is set up. In an iron matrix, for the purpose of improving sensitivity of trace chromium analysis and reducing the self-absorption of iron, the effects of key parameters are investigated. The optimal values of the parameters are found to be: 450 ns inter-pulse delay, 700 ns gate delay, 30 mJ/6 mJ pulse energy ratio, and 19.8 mm lens-to-sample distance (corresponding to a 799 μm laser focused spot size). Compared to the single-pulse system, the shot number of dual-pulse ablation is limited for reducing surface damage. After the optimization of the dual-pulse system, the signal-to-noise ratio of the trace chromium emission line has been improved by 3.5 times in comparison with the single-pulse system, and the self-absorption coefficient of matrix iron has been significantly reduced with self-reversal eliminated. The number of detectable lines for trace elements has more than doubled thus increasing the input for spectral calibration without significantly increasing the ablation mass. Three calibration methods including internal standardization, partial least squares regression and random forest regression are employed to determine the chromium and manganese concentrations in standard samples of low alloy steel, and the limit of detection is respectively calculated as 36 and 515 ppm. The leave-one-out cross validation method is utilized to evaluate the accuracy of chromium quantification, and the concentration mapping of chromium is performed on the surface of a steel sample (16MND5) with a relative error of 0.02 wt%.

Preconditioned hybrid X-pinch (HXP) experiments have been performed on the Qin-1 facility to investigate the effect of the prepulse current on the implosion dynamics and radiation characteristics. HXPs with molybdenum wires of ∼1.2 mm in length and 25 to 50 μm in diameter have been tested. Driven by the prepulse current, the molybdenum wire is heated to a core-corona structure with a Joule energy deposition of 0.5–4.8 eV/atom, which is smaller than its atomization enthalpy. The radial expansion velocity of the wire core is 0.5–3 km/s. The main current of 450 kA/400 ns is applied ∼610 ns after the prepulse current. The implosion dynamics of the preconditioned HXP is characterized by two-shell structure implosion. Immediately after the main current starts, the current mainly passes through the corona plasma located in a large radius, and the implosion of corona plasma lasts for ∼100 ns until the corona plasma collides with the wire core. Then, the current distribution switches from the corona plasma to the wire core, which results in the onset of implosion of the wire core. The implosion of the wire core generates hot spots and x-ray radiation. The calculated inductance and radius of the current sheath agree with the experimental results. The corona plasma performs as a current switch, which allows the main current passing through the wire core after 100 ns. It indirectly contributes to sharpening the main current used for implosion of the wire core. A single hot spot with x-rays over 2.5 keV is measured using the preconditioned HXP.