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The problem of dataset imbalance has raised a wide concern in many machine learning areas, but not in non-intrusive load monitoring, or load disaggregation. In this study, a pictorial evaluation method is proposed to representation the imbalance class distribution in datasets. We colored a Karnaugh maps according to the quantities of different variables combination to offer a visual impact to the whole dataset. After utilizing this method on a public dataset and its testing result, a clear imbalanced abundance in the dataset and an exciting performance have been found. A preliminary Python package to realize this mapping method has been uploaded on GitHuba.

In this paper, a 96 kJ compact synchronous discharge driver is designed. The issue of the current measurement of the six parallel gas spark switches is resolved by a multi-channel isolated current measuring system, and the driver's circuit simulation model is constructed. Then, the discharge current characteristics of each branch and load are investigated, and the results show that when the operating voltage is at least 50 kV, the parallel switches are conducted synchronously. The designed multi-channel isolated current measuring system meets the use requirements at a maximum operating voltage of 80 kV, the peak current measured by a single channel is 500 kA at this time, which corresponds to the load current of 3 MA, and the current rise time (0%–100% rise time) is about 1.15 µs. However, the asynchronous conduction of these switches will increase the branch circuit's peak current by a maximum of 25%, and the maximum value of the inverse peak current ratio of the branch will increase to 1.16, which will threaten the safe operation of the components. At this time, there is a redistribution of charge between the already conducting branches, so the impact of the load current is less than that of the basic branch current. When the conduction dispersion of the switchers is less than 452 ns, the peak current of the load reduction is less than 3%, and the current waveform meets the application requirements. The research is essential for understanding the operating status of the driver and assessing the through-current capability of the device's components, such as gas switches and capacitors. [ABSTRACT FROM AUTHOR]

Many studies have investigated the positivity rate of hepatitis B surface antibody (HBsAb) after hepatitis B vaccine (HepB) immunization. However, the antibody level, assessed monthly or at more frequent intervals after each of the three doses, particularly within the first year after birth, has not been previously reported. To elucidate the level of antibody formation at various times after vaccination, the current study used the available detection data of HBsAb in hospitalized children to analyze the HBsAb level after immunization combined with their vaccination history. Both the positivity rate and geometric mean concentration (GMC) increased sequentially with immunization doses, reaching their peaks earlier after the third dose than after the first two doses, and the rate of HBsAb positivity was able to reach 100% between 11 and 90 days after completing the three doses of HepB. Within one year after receiving the three doses, the antibody positivity rate and GMC were maintained above 90% and 100 mIU/mL, respectively, and subsequently steadily declined, reaching the lowest value in the 9th and 10th years. The current findings reveal, in more detail, the level of antibody formation at different times following each dose of HepB in hospitalized children, particularly in the age group up to one year after vaccination. For the subjects of this study, we prefer to believe that the proportion of HBsAb non-response should be less than 5% after full immunization with HepB, provided that the appropriate time for blood collection is chosen. [ABSTRACT FROM AUTHOR]

A repetitive plasma source for simulation of mitigated edge localized mode transient heat load is developed. The repetitive plasma source consists of a repetitive pulsed power supply and a pulsed plasma accelerator. The pulsed plasma accelerator is composed of a coaxial cathode, an anode, and an insulator. The inner electrode is the cathode with a diameter of 5 mm, and the outer electrode is the anode with a diameter of 15 mm. An angular magnetic field is generated by the discharge current and acts with the radial current to generate Lorentz force, which drives the plasma ejecting to the outlet. The repetitive pulsed power supply can be divided into three parts, the primary charge circuit, the resonant charge circuit, and the discharge circuit. The time interval between resonant charge and discharge is 4 ms. The repetitive discharge components include ten modules running in parallel. There are four working modes for discharge components, depending on the number of simultaneously discharged modules. For Mode A, the maximum repetitive frequency is 50 Hz, and the transient heat load is 0.06 MJ/m2 when the discharge current is 10.5 kA. For Mode D, the maximum repetitive frequency is 5 Hz, and the transient heat load is 0.45 MJ/m2 when the discharge current is 66 kA. This is of great significance for the study of the interaction between plasma and plasma-facing materials in tokamak. [ABSTRACT FROM AUTHOR]

We experimentally and theoretically study the coupling between magnons and microwave photons at zero static magnetic field in a system combined by a planar superconducting cavity and a van der Waals antiferromagnetic insulator CrCl3 crystal. Using high-temperature superconductor DyBaCO, we fabricate a planar superconducting cavity with a high-quality factor. The antiferromagnetic resonance of CrCl3 has a finite resonance frequency within a microwave electronics range at zero static magnetic field, and this frequency is sensitive to the temperature. Tuning the temperature to make the antiferromagnetic resonance mode of CrCl3 approaching the cavity mode, we experimentally achieve the coupling between the magnon in CrCl3 and the microwave photon in cavity. An anticrossing feature of the transmission spectra mapping indicates the coupling of magnons and photons at zero static magnetic field. The cooperativity of the hybrid system is 76, indicating a strong coherent information exchange between photons and magnons in CrCl3. [ABSTRACT FROM AUTHOR]

2D transition metal dichalcogenides are promising candidates for high‐performance photodetectors. However, the relatively low response speed as well as the complex transfer process hinders their wide applications. Herein, for the first time, the fabrication of a few‐layer MoTe2/Si 2D–3D vertical heterojunction for high‐speed and broadband photodiodes by a pulsed laser deposition technique is reported. Owing to the high junction quality, ultrathin MoTe2 film thickness, and unique vertical n–n heterojunction structure, the photodiode exhibits excellent device performance in terms of a high responsivity of 0.19 A W−1 and a large detectivity of 6.8 × 1013 Jones. The device is also capable of detecting a broadband light with wavelength spanning from 300 to 1800 nm. More importantly, the device possesses an ultrahigh response speed up to 150 ns with a 3‐dB electrical bandwidth approaching 0.12 GHz. This work paves the way toward the fabrication of novel 2D–3D heterojunctions for high‐performance, ultrafast photodetectors. [ABSTRACT FROM AUTHOR]

Here, we demonstrate a novel 2-D–3-D graphene (Gr)/MoS2/Si nanowires Schottky-NP bipolar van der Waals heterostructure, which allows the combination of the unique properties of 2-D layered materials with the proven merits of well-developed silicon technologies. Significantly, the resultant devices exhibit an ultrahigh response speed of 17 ns with a broad spectral response characteristic, which represents most fast response for 2-D transition metal dichalcogenide (TMD)-based photodetectors and is comparable to that of commercial Si photodetectors. A high responsivity of 0.6 A $\text{W}^{-{1}}$ and a detectivity of ${8}\times {10}^{{12}}$ Jones are also achieved. This result suggests a pathway for the fabrication of high-speed photodetectors based on TMDs. [ABSTRACT FROM AUTHOR]

This paper gives an experimental demonstration of non-line-of-sight (NLOS) visible light communication (VLC) using a single 80 μm gallium nitride (GaN) based micro-light-emitting diode (micro-LED). This device shows a 3-dB electrical-to-optical modulation bandwidth of 92.7 MHz. IEEE 802.11ac modulation scheme with 80 MHz bandwidth, as an entry level of the fifth generation of Wi-Fi, was employed to use the micro-LED bandwidth efficiently. These practical techniques were successfully utilized to achieve a demonstration of line-of-sight (LOS) VLC at a speed of 433 Mbps and a bit error rate (BER) of 10−5 with a free space transmit distance 3.6 m. Besides this, we demonstrated directed NLOS VLC links based on mirror reflections with a data rate of 433 Mbps and a BER of 10−4. For non-directed NLOS VLC using a print paper as the reflection material, 16 QAM, 195 Mbps data rate, and a BER of 10−5 were achieved. [ABSTRACT FROM AUTHOR]

This letter reports the first demonstration of 1-kV-class AlN Schottky barrier diodes on sapphire substrates by metal organic chemical vapor deposition. The device structure mimics the silicon-on-insulator (SOI) technology, consisting of thin $n$ -AlN epilayer as the device active region and thick resistive AlN underlayer as the insulator. At room temperature, the devices show outstanding performances with a low turn-ON voltage of 1.2 V, a high ON/OFF ratio of \sim 10^{5} , a low ideality factor of 5.5, and a low reverse leakage current below 1 nA. The devices also exhibit excellent thermal stability over 500 K owing to the ultra-wide bandgap of AlN. The breakdown voltage of the devices can be further improved by employing field plate, edge termination technologies, and optimizing the SOI-like device structure. This letter presents a cost-effective route to high performance AlN-based Schottky barrier diodes for high-power, high-voltage, and high-temperature applications. [ABSTRACT FROM AUTHOR]

We implement finite difference method (FDM) to calculate the optical cavity effects in InGaN micro-light-emitting diodes (LEDs) with metallic coating. The dispersion relation, mode profile, energy density W of electromagnetic field, cavity quality factor Q, and effective mode area Ae\,f\,f are theoretically investigated. The results show that although the strongest confinement of the field is achieved by surface plasmon modes at GaN/Ag interface, the energy density W is small inside the cavity, leading to a high effective mode area. Additionally, the cavity without metallic coating has the highest $Q$ factors since no metal loss is involved. These results can serve as guidelines for the design and fabrication of high efficiency and high speed LEDs for the applications of solid-state lighting and visible-light communication. [ABSTRACT FROM PUBLISHER]

We study verticalGaN p-n and Schottky power diodes with different buffer layer thicknesses grown on free-standingGaN substrates, using metalorganic chemical vapor deposition. High breakdown voltage of > 1 kV and low specific on-resistance of 3 \textm\Omega \cdot cm ^2 are achieved on GaN p-n diode with 1~\mu \textm buffer layer and 9~\mu \textm drift layer without passivation or field plate. Detailed device analysis on GaN Schottky diodes indicates that buffer layer has significant impacts on the electrical properties of drift layer and thus device performances of GaN p-n diodes. A thicker buffer layer will significantly enhance the breakdown voltages of these devices, which is possibly due to the improved material quality of drift layers with reduced defect densities. Higher doping concentration in drift layer with thicker buffer layer will, however, lower breakdown voltage. More discussions reveal improving the material quality of drift layer plays amore dominant role in achieving high breakdown GaN-on-GaN p-n and Schottky diodes with increasing buffer layer thickness. [ABSTRACT FROM PUBLISHER]

The superior low-efficiency droop performance of semipolar (20\bar2\bar1) InGaN light-emitting diodes (LEDs) makes it a hot candidate for efficient solid-state lighting and full-color displays. To unveil the mystery of this low droop and high efficiency, the emission dynamics of semipolar (20\bar2\bar1) LEDs is investigated by time-resolved and steady-state photoluminescence (PL) measurements. Much smaller carrier lifetimes (radiative and nonradiative lifetime) were obtained from semipolar (20\bar2\bar1) InGaN QWs compared with those on the c-plane samples, possibly due to the reduced quantum-confined Stark effects and smaller indium fluctuation on semipolar InGaN samples. The experimental findings indicate a much reduced excess carrier density in semipolar (20\bar2\bar1) InGaN LEDs, which will impact the device performance. Based on this, a modified ABC equation with weak phase-space-filling (PSF) effect was used to model the droop characteristics of semipolar (20\bar2\bar1) LEDs. [ABSTRACT FROM PUBLISHER]