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RISS 인기검색어
- 검색키워드
- 저자 : Pan Junjie (검색결과 6 건)
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Liu Liu,Pan Luo,Junjie Zhao,Yuechen Rui 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.11
The rotating high-frequency (RHF) signal injection method is widely adopted for the initial position estimation in sensorless permanent magnet-assisted synchronous reluctance motor (PMa-SynRM) drives due to its simple implementation. However, the position estimation accuracy of the conventional method may be seriously deteriorated by the dead-zone effects of the inverter and the cross-saturation effects of the machine. Thus, to improve initial position estimation accuracy, a strategy to apply dual RHF signals is proposed in this paper. Different from the traditional solution, the proposed method sequentially injects dual RHF carrier voltages with the same frequencies but different amplitudes into the machine. Objective equations that consider the dead-zone and cross-coupling effects can be extracted from high-frequency response currents in turn. After the simple calculation, the initial position can be obtained directly and accurately, which effectively minimizes the influences of machine cross-saturation and inverter nonlinearities. The influence of the system delay on the rotor position estimation is also analyzed and deduced in detail. Finally, experimental results on a 5.5-kW PMa-SynRM indicate that the proposed method can achieve precise initial position estimation under any rotation position.
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Li Zhigang,Pan Junjie,Xia Bangyang,Qiang Shenglong,Lu Wei,Li Qing 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.9
As an important part of the digital reactor, the pin-by-pin wise fine coupling calculation is a research hotspot in the field of nuclear engineering in recent years. It provides more precise and realistic simulation results for reactor design, operation and safety evaluation. CORCA-K a nodal code is redeveloped as a robust pin-by-pin wise neutronics and thermal-hydraulic coupled calculation code for pressurized water reactor (PWR) core. The nodal green's function method (NGFM) is used to solve the threedimensional space-time neutron dynamics equation, and the single-phase single channel model and one-dimensional heat conduction model are used to solve the fluid field and fuel temperature field. The mesh scale of reactor core simulation is raised from the nodal-wise to the pin-wise. It is verified by two benchmarks: NEACRP 3D PWR and PWR MOX/UO2. The results show that: 1) the pin-by-pin wise coupling calculation system has good accuracy and can accurately simulate the key parameters in steadystate and transient coupling conditions, which is in good agreement with the reference results; 2) Compared with the nodal-wise coupling calculation, the pin-by-pin wise coupling calculation improves the fuel peak temperature, the range of power distribution is expanded, and the lower limit is reduced more
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Penghui Cao,Junjie Tan,Xuezhen Liao,Jinwei Wang,Lihuan Chen,Ziyan Fang,Nannan Pan 대한소아청소년 정신의학회 2024 소아청소년정신의학 Vol.35 No.1
Objectives: This study aimed to explore the influence of depression severity, disease course, treatment status, and other factors on cognitive function in adolescents with depressive disorders. Methods: Participants who met the inclusion criteria were enrolled in the study. Sociodemographic data of each participant were recorded, including age, sex, and family history of mental disorders. Zung’s Self-Rating Depression Scale was used to assess depression status in adolescents. Moreover, P300 and mismatch negativity (MMN) were used to objectively evaluate the participants’ cognitive function. Results: Only 26.8% of the adolescents with depression received standard antidepressant treatment. The latencies of N2 (267.80±23.34 ms), P3 (357.71±32.09 ms), and MMN (212.10±15.61 ms) in the adolescent depression group were longer than those in the healthy control group (p<0.01). Further analysis revealed that the latency of MMN was extended with increased levels of depression in adolescents. The MMN latency was short in participants with depression receiving standardized treatment. Furthermore, the latency of MMN was positively correlated with the severity and duration of depression (correlation coefficients were 0.465 and 0.479, respectively) (p<0.01). Conclusion: Receiving standardized treatment and shortening the course of depression can reduce cognitive impairment in adolescents with depression.
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Low-loss carrier-stored IGBT with p-type Schottky diode-clamped shielding layer
Yi, Bo,Zhao, Qing,Zhang, Qian,Cheng, JunJi,Huang, HaiMeng,Pan, YiLan,Hu, XiaoRan,Xiang, Yong The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.8
A novel carrier-stored trench bipolar transistor (CSTBT) with heavily doped carrier-stored layer (CSL) is proposed and investigated by TCAD tools. The voltage of CSL is shielded by a buried p-type layer (P-bury) whose potential is clamped by a p-type Schottky Barrier Diode (pSBD) in series-connection with a PN diode. Hence, the CSL can be heavily doped, and the trade-off between on-state voltage drop (V<sub>on</sub>) and turn-off loss (E<sub>off</sub>) is substantially improved. Compared with that of a conventional CSTBT with floating P-base (FP-CSTBT), the E<sub>off</sub> of the proposed CSTBT is reduced by 27.9% at V<sub>on</sub>=1.1 V. Owing to the shielding effect of the P-bury layer, the saturation current density of the proposed CSTBT is reduced by 52% compared with that of the FP-CSTBT. Consequently, significantly enlarged short-circuit safe operation area is obtained, and the short-circuit withstand time (t<sub>sc</sub>) is increased to 12.8 s at ultra-low V<sub>on</sub> (~1.1 V).
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A fast image-stitching algorithm for characterization of cracks in large-scale structures
Linlin Wang,Billie F. Spencer Jr,Junjie Li,Pan Hu 국제구조공학회 2021 Smart Structures and Systems, An International Jou Vol.27 No.4
Visual inspection of concrete cracks has been widely used in structural health monitoring (SHM). Capturing highresolution images is an effective method to visualize a complete crack, but it is difficult to show a whole crack from a single high-resolution image. One feasible method is using image stitching technique to stitch several images into a complete crack map. However, the current image stitching method is a computationally intensive process. Numerous images are required to cover large-scale structures with sufficient resolution, this can be computationally prohibitive. To address this problem, an improved image stitching method for crack damage evaluation is proposed, which can quickly stitch the crack images without affecting the quality of the stitching or the resulting images. Rather than first stitching the images together and then determining the crack maps, we propose to first develop the crack maps for the individual images and then stitch them together. The proposed method reduces the number of redundant matching points between the original images by combining their characteristics during image stitching, so it can reduce the calculation time without affecting the quality. Also, the results will not be influenced by the image stitching seam, which can reduce the complexity of the algorithm. Several experimental results are provided in this article to demonstrate that the proposed method can reduce the calculation time without affecting the quality of image stitching and have better robustness than the current method in use.
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