通讯机构：
[Li-an Bian] S;[Kai-da Xu] Y;School of Physics & Electronic Science, Changsha University of Science and Technology, Changsha 410114, China<&wdkj&>Hunan Province Higher Education Key Laboratory of Modeling and Monitoring on the Near-Earth Electromagnetic Environments, Changsha University of Science and Technology, Changsha 410114, China<&wdkj&>Yangtze Delta Region Institute (Quzhou), University of Electronic Science and Technology of China, Quzhou 324000, Zhejiang, China<&wdkj&>School of Information and Communications Engineering, Xi’an Jiaotong University, Xi’an 710049, China
摘要：
The wide distribution of the lateral size of lab-prepared graphene oxide (GO) sheets often complicates the measurement of accurate average size. Herein, a series of reduced-GO/polyethyleneimine (RGO/PEI) composite membranes with compact brick-wall structures were successfully prepared. The large lateral size of RGO sheets in the membrane benefited gas barrier properties, including oxygen, nitrogen, and water vapor. The RGO sheets acted as impermeable inorganic filler to prolong the diffusion path, forcing gas molecules to wiggle through the permeable and tortuous channels of the PEI/water mixture. The water vapor transmission rate of RGO/PEI composite membranes was relatively high, and a linear correlation was established between the length of PEI/water channels and the water vapor barrier property. The length of PEI/water channels under the same membrane thickness was determined by the lateral size of RGO sheets. Therefore, the statistic averages of lateral size of RGO sheets (from 2.48 & mu;m to 44.35 & mu;m) showed a linear correlation with the water vapor barrier property, as confirmed by the positron annihilation technique and molecular dynamics simulations. In sum, the linear correlation could be used to practicably measure the statistic averages of lateral size of GO sheets according to water vapor permeability measurements.
关键词：
3D modeling;Teeth;Optical engineering;Reconstruction algorithms;Image segmentation;Contour extraction;Detection and tracking algorithms;Object detection;Image enhancement;Point clouds
摘要：
Common line-structured light center extraction algorithms have limitations in accuracy and robustness when extracting the center of line-structured light obtained from objects with complex surface structures. In this study, we propose a high-precision center extraction algorithm for multi-curvature line-structured light. This algorithm improves the enhanced parallel thinning algorithm to eliminate redundant points and burrs and fills for missing center points at the end of the light stripe via the improved internal propulsion center extraction algorithm. Finally, sub-pixel centers are recalculated in the direction of the normal vector. A comparative experiment using three classical algorithms was conducted based on a tooth model with a complex curved surface. The experimental results show that the mean absolute error of this algorithm is <0.1, which is only half that of the best-performing dual-threshold grayscale center-of-gravity method in the classical method. Extraction of the center can be performed for multi-curvature line-structured light over 20 curvatures in the range of ( 0.0001 , 4.1439 ) / pixel (- 1); moreover, the end of the light stripe and the identification of the truncation can be improved. Therefore, the proposed algorithm is suitable for contour detection of multi-curvature targets and effectively improves the accuracy of high-precision object detection.
通讯机构：
[Wu, L.] C;Changsha University of Science and Technology, China
关键词：
Electron extracting;shorted-anode silicon-on-insulator lateral insulated-gate bipolar transistor (SA SOI LIGBT) forward voltage drop (VON);snapback-free;turn-off loss (EOFF)
摘要：
In this work, a novel shallow oxide trench (SOT) shorted-anode (SA) silicon-on-insulator (SOI) lateral insulated-gate bipolar transistors (LIGBTs) with an adaptive electron channel (AEC) in anode is proposed and investigated by numerical simulations. The AEC is controlled by a polysilicon electrode on the right side of the device and connected to anode, while an SOT and a P+ area are used to separate the P+ anode and N+ anode. At low anode voltage ( ${V}_{A}$ ), the AEC shows strong resistance to electrons, resulting in the N+ anode to be blocked. Once a high ${V}_{A}$ is applied, the channel will open allowing electrons to flow through. On this basis, the device can achieve low forward voltage drop ( ${V}_{ \mathrm{\scriptscriptstyle ON}}$ ) and reduce the turn-off loss ( ${E}_{ \mathrm{\scriptscriptstyle OFF}}$ ) without snapback effect. Compared to separated SA LIGBT (SSA LIGBT), a much smaller dimension of cell pitch with enhanced performance is achieved in this new structure. The simulation results demonstrate that ${V}_{ \mathrm{\scriptscriptstyle ON}}$ reduces by 28.4% under the same ${E}_{ \mathrm{\scriptscriptstyle OFF}}$ and ${E}_{ \mathrm{\scriptscriptstyle OFF}}$ reduces by 28.0% under the same ${V}_{ \mathrm{\scriptscriptstyle ON}}$ when compared to conventional (Conv.) LIGBT. Moreover, further simulations on the safe operating area (SOA) reveal that the proposed structure possesses better reliability than the SSA LIGBT.
摘要：
In this paper, a one-bit coding metasurface comprised of 20 columns is proposed to achieve amplitude and phase modulation. Each column is dynamically controlled by p-i-n diodes to modulate the incident electromagnetic waves. By synthesizing the code sequence, the radar cross section (RCS) of the surface can be reduced to specific values. With shift coding and inverse code sequence, the metasurface can also achieve phase modulation function with almost the same amplitude responses. A metasurface prototype is fabricated and measured, showing an obvious RCS reduction in a 35.2% bandwidth from 7 to 10 GHz. Specifically, a high RCS reduction of 23 dB can be achieved at 8.5 GHz. In addition, the metasurface exhibits the capability of phase modulation with responses of 60 +/- 15 degrees and 140 +/- 30 degrees, while the amplitude responses are almost the same. Overall, the proposed dynamic metasurface is useful for radar jamming, which is expected to further improve the stealth performance of the target.
期刊：
Journal of Molecular Modeling,2023年29(12):1-11 ISSN：1610-2940
通讯作者：
Hong, JX
作者机构：
[Hong, JX; Hong, Jinxiang; Fan, Jin; Xu, Zhenghong] State Key Lab High Performance Civil Engn Mat, Nanjing 210008, Peoples R China.;[Gong, Minghui; Hong, JX; Hong, Jinxiang; Fan, Jin; Xu, Zhenghong] Sobute New Mat Co Ltd, Nanjing 211000, Jiangsu, Peoples R China.;[Xiong, Zijia] Southeast Univ, Sch Transportat, 2 Southeast Univ Rd, Nanjing 211189, Peoples R China.;[Zeng, Qing] Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha 410114, Peoples R China.
通讯机构：
[Hong, JX ] S;State Key Lab High Performance Civil Engn Mat, Nanjing 210008, Peoples R China.;Sobute New Mat Co Ltd, Nanjing 211000, Jiangsu, Peoples R China.
摘要：
CONTEXT: Graphene oxide(GO) has been widely used in asphalt modification due to its excellent properties. To reveal the interaction effect between GO and asphalt materials, the microscopic behavior and molecular structure changes of asphalt and GO/asphalt were investigated by molecular dynamics (MD) simulations. Mean square displacement (MSD) results showed that GO significantly inhibited the diffusion of molecules of asphalt components. Radial distribution function (RDF) results that GO destroys the original sol-type structure of asphalt. Simultaneously, GO adsorbed resins at low-temperature, adsorbed asphaltenes at high-temperature, and dispersed as a dispersed phase in the light components. The concentration of the dispersed phase in the asphalt colloidal structure was increased and the mutual attraction was enhanced. This improves the deformation resistance at high temperature, but weakens the ductility at low temperatures. METHODS: To investigate the mechanism of action of GO-modified asphalt, the asphalt model and the GO/asphalt composite system model were constructed using the Amorphous Cell module in Materials Studio 2020 software. Subsequently, molecular dynamics simulations of the GO/asphalt composite system were performed using the Forcite module, while the interactions between atoms and molecules were described using the COMPASS II force field.
期刊：
2023 4th International Conference on Computer Vision, Image and Deep Learning (CVIDL),2023年:613-616
作者机构：
[Qiudi Zhang; Zhonglei Gao; Xinglong Zhang] School of Physics and Electronic Sciences, Changsha University of Science and Technology, Changsha, China
摘要：
Due to the complexity of driving surroundings, current advanced driving assistance system struggle to reliably extract lane lines. Unlike most methods that select or filter potential lane lines step-by-step according to different features, this paper proposes a new detection method that creates a scoring mechanism based on lane line features, which combines multiple lane line features for comprehensive judgment, providing a new idea to detect lane lines using conventional computer vision methods. First, the region of interest (ROI) is defined and a priority pixel method is used to binarize the image after converting to grayscale. The gradient image of the binary image is then extracted using the Sobel operator and converted to an 8-bit (uint8) data format for further processing. Contour detection is then performed on the binary image, and a scoring mechanism is used to select lane contours. After that, performing an AND operation between the mask containing only the pixels within the contours of the lane line and the gradient image yields the points used to fit the lane lines. Finally, the lane lines are fitted using the least squares method. The experimental results indicate that the method proposed can significantly improve the accuracy of detection.
摘要：
A 15-kV-scale 4H-SiC insulated-gate bipolar transistor (IGBT) with a self-biased split-gate pMOS (SGPMOS) is proposed and simulated in this work. By introducing the SGPMOS, the proposed IGBT forms a hole barrier in the ON-state and a hole extraction path during the turn-on and turn-off transient, respectively. Compared to GS IGBT, the ON-state voltage ( ${V}_{\text {ON}}{)}$ of the SGPMOS IGBT is decreased by 54.95% for the same turn-off loss ( ${E}_{\text {off}}$ ). Meanwhile, compared with pMOS IGBT, the ${C}$ – ${V}$ and gate charge ( ${Q}_{g}{)}$ characteristics exhibit that the Miller capacitance ( ${C}_{\text {gc}}{)}$ and ${Q}_{g}$ of the SGPMOS IGBT are reduced by 56.60% and 35.85%, respectively. Moreover, SGPMOS can extract the hole accumulated both under the gate oxide and in the P-shield region during the turn-on transient. This diminishes reverse displacement current ( ${I}_{G\_{}{\text {dis}}}{)}$ , contributing to low electromagnetic interference (EMI) noise. Simulation results demonstrate that, compared to pMOS IGBT, the SGPMOS IGBT achieves better controllability in peak turn-on current ( ${I}_{\text {max}}{)}$ and turn-on $\text{d}{I}_{C}/\text{d}{t}$ , featuring a 52.75% lower maximum reverse recovery $\text{d}{V}_{\text {KA}}/\text{d}{t}$ for the same turn-on loss ( ${E}_{\text {on}}{)}$ .
摘要：
We explore the nucleons and A isobars under strong magnetic fields in Skyrme models. The effects of the derivative dependent sextic term in Skyrme Lagrangian are investigated. When the Skyrmion is quantized, the role of the nondiagonal elements in the kinematical term is discussed. The present work has shown the nontrivial impacts on the properties of the nucleons and A isobars.
通讯机构：
[Zheng, B ] C;Changsha Univ Sci & Technol, Sch Comp & Commun Engn, Changsha 410114, Peoples R China.
关键词：
small target detection;Mul-BiFPN;M-SimAM;Focal EIoU
摘要：
At present, UAV aerial photography has a good prospect in agricultural production, disaster response, and other aspects. The application of UAVs can greatly improve work efficiency and decision-making accuracy. However, owing to inherent features such as a wide field of view and large differences in the target scale in UAV aerial photography images, this can lead to existing target detection algorithms missing small targets or causing incorrect detections. To solve these problems, this paper proposes a small target detection algorithm for UAV aerial photography based on improved YOLOv5s. Firstly, a small target detection layer is applied in the algorithm to improve the detection performance of small targets in aerial images. Secondly, the enhanced weighted bidirectional characteristic pyramid Mul-BiFPN is adopted to replace the PANet network to improve the speed and accuracy of target detection. Then, CIoU was replaced by Focal EIoU to accelerate network convergence and improve regression accuracy. Finally, a non-parametric attention mechanism called the M-SimAM module is added to enhance the feature extraction capability. The proposed algorithm was evaluated on the VisDrone-2019 dataset. Compared with the YOLOV5s, the algorithm improved by 7.30%, 4.60%, 5.60%, and 6.10%, respectively, in mAP@50, mAP@0.5:0.95, the accuracy rate (P), and the recall rate (R). The experiments show that the proposed algorithm has greatly improved performance on small targets compared to YOLOv5s.
通讯机构：
[Lijuan Wu] H;Hunan Provincial Key Laboratory of Flexible Electronic Materials Genome Engineering, The School of Physics and Electronic Science, Changsha University of Science and Technology, Changsha, China
关键词：
Breakdown voltage (BV);Insulated gate bipolar transistor (IGBT);On-state voltage (V on);Superjunction (SJ);Turn-off loss (E off)
摘要：
A superjunction (SJ) insulated gate bipolar transistor (IGBT) featuring an embedded self-biased (ESB) n-type metal-oxide-semiconductor field-effect transistor (NMOS) between the P-pillar and the emitter is proposed and simulated. During the on-state, the NMOS is turned off to maintain high conductivity modulation, achieving a relatively low on-state voltage (V-on). The P-pillar is connected to the emitter through the NMOS in the blocking state, which prevents premature breakdown at the corner of the trench gate. Consequently, a high breakdown voltage (BV) is ensured. During the turn-off period, the embedded self-biased NMOS turns on adaptively with the increasing potential of the P-pillar. An extra path is formed to extract excessive carriers in the drift region, thereby minimizing turn-off losses (E-off). Numerical simulations show that a 48.9% reduction in V-on is achieved for the proposed IGBT when compared with the conventional (Con.) SJ IGBT at the same E-off. Furthermore, the E-off of the proposed IGBT is reduced by 23.8% and the BV is improved by 21.5% compared to the SJ IGBT with a floating P-pillar (FP SJ IGBT) at the same V-on.
通讯机构：
[Akira Nagaoka] R;Research Center for Sustainable Energy & Environmental Engineering, University of Miyazaki, Miyazaki 889-2192, Japan<&wdkj&>Electrical and Electronic Engineering Program, University of Miyazaki, Miyazaki 889-2192, Japan
摘要：
Point defect chemistry strongly affects the fundamental properties of materials and has a decisive impact on device performance. The Group-V dopant is prominent acceptor species with high hole concentration in CdTe; however, its local atomic structure is still not clear owing to difficulties in definitive measurements and discrepancies between experimental observations and theoretical models. Herein, we report on direct observation of the local structure for the As dopant in CdTe single crystals by the X-ray fluorescence holography (XFH) technique, which is a powerful tool to visualize three-dimensional atomic configurations around a specific element. The XFH result shows the As substituting on both Cd (AsCd) and Te (AsTe) sites. Although AsTe has been well known as a shallow acceptor, AsCd has not attracted much attention and been discussed so far. Our results provide new insights into point defects by expanding the experimental XFH study in combination with theoretical first-principles studies in II-VI semiconductors.
