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Measurement of the carrier transport in the GaAs photoconductive semiconductor switch (PCSS) is important for the study of the GaAs PCSS current filament and the design of improved GaAs PCSS devices. In this study, an optical testing method was proposed for the measurement of the time-dependent carrier density distribution in the GaAs PCSS. The measured electron density curves show that the carrier density distribution between the two electrodes is nonuniform for Δt = 0, and as Δt increase from 0.6 ns to 6 ns, a large number of carriers concentrate near the anode of the GaAs PCSS. These phenomena are analyzed in detail and the measured curves are found to be in good agreement with the simulation results.

This letter focuses on the power module (PM) capacitor voltage balancing of a $\pm 350$ -kV/1000-MW modular multilevel converter (MMC). For this MMC, the current flowing through the IGBTs will exceed the nominal current of the adopted commercial high-voltage (3.3 kV or higher) IGBT products, i.e., 1500 A. As for the PM voltage balancing of this MMC, the switching frequency must be kept low to reduce the losses and the accurate calculation of the PM switching frequency is of great importance to the design of the cooling system. This letter presented a low-switching frequency PM balancing method by introducing the balancing adjusting number (BAN). The PM switching frequency calculation method is also presented with different BANs. Computer simulation and the real-time control hardware in the loop test results based on RT-LAB show the effectiveness of the proposed PM balancing method and the accuracy of the switching frequency calculation method under the rated power.

Purpose To examine the cognition, spontaneous epilepsy, and electroencephalography (EEG) characteristics of rats with malformations of cortical development (MCD) and their use as an animal model for investigating the pathogenesis of intractable epilepsy and screening novel antiepileptic drugs. Methods An epileptic rat model of MCD was established with the F1 generation of pregnant rats after X-irradiation with 175 cGy (Group L), 195 cGy (Group M), or 215 cGy (Group H). Long-term video-EEG monitoring was used to record the seizures in the rats with MCD. Cognition was assessed with the Morris water maze. The EEGs were recorded and analyzed in the frontal and parietal lobes and hippocampi of adult rats. Finally, the brain tissues were processed for Nissl staining. Results The model groups exhibited markedly prolonged escape latencies and distinct decrements in the percent distance traveled in the target quadrant and platform-crossing frequency. These findings were dose-dependent. Frequent interictal epileptiform discharges were observed in the frontal and parietal lobes and hippocampi of adult rats, and their incidences were markedly higher in the model groups compared with that in the normal controls, with Group M having the highest incidence. Spontaneous seizures were observed in the model groups (mean incidence, 46.7%). The daily mean frequency of seizures and the incidence of spontaneous seizures were highest in Group M. Nissl staining revealed a dose-dependent pattern of hippocampal abnormalities, cortical and subcortical nodular heterotopia, and callosal agenesis in the model groups. Conclusion The 195 cGy dose was most appropriate for establishing an epileptic model of MCD with X-irradiation.

The PEO process is a useful surface technology to improve wear performance and corrosion resistance on light metals such as Mg, Al and Ti and their alloys. It has been studied for several decades, but up to now, its mechanism is still not fully understood. In order to improve the understanding of PEO process and get better process design for industrial application, it is worth studying numerical approaches of the PEO process. This thesis provides a modeling and simulation approach to study the PEO process on Mg alloy AM50 under constant voltage mode. A numerical model has been built to describe the PEO process using Finite Element Method in COMSOL. Experiments are performed to provide data input for the modeling and simulation, and also to validate the correctness and usefulness of the modeling. From comparison, the simulation result of coating thickness is in good agreement with the experimental result. The application of the model was verified by studies investigating the influences of different voltage, a complex substrate geometry and the electrode distance on the formation of PEO coatings. The approach of the model can predict the coating thickness close to the experimental results and explain the effects of the main process parameters on the coating growth reasonably. Therefore, the methodology provided by the numerical model has been demonstrated to be a useful tool for predicting the coating thickness and explaining the effects of different parameters on Mg alloy under constant voltage mode.

Objective. The outcomes of biatrial ablation (BA) and isolated left atrial ablation (LA) in atrial fibrillation remain inconclusive. In this meta-analysis, we assess the currently available evidence to compare outcomes between BA and LA. Methods. Electronic searches were performed from database inception to December 2016, and relevant studies were accessed. Odds ratios and weight mean differences with 95% confidence intervals are reported. Twenty-one studies comprising 3609 patients were included in the present meta-analysis. Results. The prevalence of sinus rhythm in the BA cohort was similar to that in the LA cohort at discharge, at 12 months, and after more than 1 year of follow-up. However, at 6 months, the prevalence of sinus rhythm was higher in the BA cohort than in the LA cohort. The rate of permanent pacemaker implantation was higher in the BA cohort than in the LA cohort. However, 30-day and late mortality and neurological events were similar between the BA and LA groups. Conclusion. There was no significant difference in the rate of restored sinus rhythm, the risk of death, and cerebrovascular events between BA and LA, but BA had a higher rate of permanent pacemaker implantation.

Table S1. Sampling information in the present study. (DOCX 12 kb)

Pulsed power research for military and civil applications has been conducted at the China Academy of Engineering Physics (CAEP) for more than 50 years. The pulsed power research activities include development of pulsed power components, such as different kinds of high-voltage switches, series of pulsed power sources and pulsed X-ray machines, high-current accelerators for $Z$ -pinch and flash X-ray radiography, as well as medical application and electromagnetic launch. The most recent progress of pulsed power research at CAEP will be presented.

Real-time simulation of modular multilevel converter (MMC)-based HVDC is one of the most important and difficult technologies in the area of power electronics research. This paper presents a methodology for the hardware in loop (HIL) CPU/FPGA-based real-time simulation of a one-terminal MMC HVDC of up to 468 levels using a detailed equivalent model, and the simulation system is based on full-scale physical control system, including actual sub module control boards. The testing subject control system and the accompanying one are based on same hardware and symmetric structure, without expensive third part HIL simulation system, such as RT-lab or RTDS. Small time-step sub module transient simulation in device level with FPGA based parallel computing is discussed in this paper.

Because the numerous nonlinear components and fiber interfaces are used in Module Multiple Converter (MMC), the HIL test of MMC with detailed EMT model and the full-scale interface is hard to be implemented. In recent years, this existing disadvantage caused the MMC controller hardware and software difference between the HIL test and real project. In this paper, a detailed EMT model of hybrid MMC fitting for full-scale interface HIL test is proposed, and the equivalent arm circuit of hybrid MMC and the nonlinear feature of the sub-module are introduced. Then the full-scale interface HIL test system is built to test the performance of proposed model under various conditions. Comparing with the reference model built in MATLAB with detailed semiconductor model, the accuracy of the proposed method can meet the requirement of HIL tests, the current difference of two methods is less than 0.73% and the capacitor voltage difference is less than 0.39%. Due to the full-interface structure, the proposed method can simulate the divergence of capacitor voltage and all faults of the submodule. The MMC controller tested by the proposed method can be directly used in the real project without hardware and software modification.

Magnesium alloys have been used as biodegradable implants in load bearing applications due to their biodegradability and excellent mechanical properties. However, the rapid corrosion rate still needs to be improved by surface modification, and so does the biocompatibility according to clinical demands for bone implants. This study demonstrated the effectiveness of applying a bio-composite coating on magnesium alloy by adding HA particles in electrolyte during MAO process (MAO–HA). The results suggested that HA particles took part in MAO process, getting decomposed into Ca3(PO4)2 under a high temperature caused by the intense micro-arc discharge generated at high applied voltage. In the meantime, synthesis of Mg3(PO4)2 was promoted under the high temperature. The sintering-caused phases Ca3(PO4)2 and Mg3(PO4)2 combined with HA composed the bioactive coating. Testified by scratch test, electrochemical test and short-term immersion test, the composite coating showed high bonding strength and improved corrosion resistance owning to the sintering-caused products sealed partial pores of the MAO coating. Therefore, this study indicated that the bio-composite coating obtained by MAO–HA process may be suitable for synthesizing promising bone implant materials in clinical application.