Analysis on harmonic characteristics of interleaving paralleled static inverters under asymmetric conditions

Chen, Yihan,Guo, Honghao,Ma, Haixiao,Liu, Chengzi The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.1

With the large number of applications for multi electric aircraft (MEA), the power capacity of the aviation static inverter (ASI) has been continuously improved. Therefore, more and more modular parallel-based topologies are being used in the ASI to achieve power expansion. Combined with carrier phase-shift modulation, the harmonic components of a system can be further reduced. However, due to the parameter asymmetry between paralleled modules and power system disturbances, additional low frequency and DC bias components are superimposed on the control signal. This paper uses exponential function analysis to analyze the harmonic distribution of a modular ASI based on carrier phase-shift modulation under non-ideal conditions. In addition, the distribution characteristics of different paralleled topologies are compared. Finally, the correctness of the theoretical analysis is verified by simulation and experimental results.

Optimal design of control loop parameters and impedance spike suppression for 400 Hz two‑module series structured inverters

Yihan Chen,Honghao Guo,Haixiao Ma,Hui Gao 전력전자학회 2024 JOURNAL OF POWER ELECTRONICS Vol.24 No.5

The structure of a DC–DC converter connected in series with a 400 Hz inverter is widely used in aviation airborne and ground power systems to provide a medium-frequency AC power supply within a wide input voltage range. To guarantee the dynamic and steady-state performance of a multi-module series converter, it is necessary to individually optimize the control loop and the parameters of each series-connected module. In addition, it is also necessary to consider the input–output impedance matching issues of each converter. In this study, a phase-shifted full-bridge converter employing an average current control strategy is used as the input-side DC–DC converter, and a medium-frequency three-phase four-leg inverter is used as the output-side inverter. The study also conducts a small-signal modeling analysis to reveal the intrinsic relationship between the closed-loop output impedance of the input-side converter and the circuit parameters. It summarizes the optimization criteria for controlling the parameters of the voltage and current loops. By suppressing the peaks of the output impedance of the input-side converter, the impedance matching between the input- and output-side converters is ensured over the entire frequency range, ensuring the stable operation of the overall system. Finally, the correctness of the theoretical analysis is verified through simulation and experimentation.

Selecting Test Cases for Result Inspection to Support Effective Fault Localization

Yihan Li,Jicheng Chen,Fan Ni,Yaqian Zhao,Hongwei Wang 한국정보과학회 2015 Journal of Computing Science and Engineering Vol.9 No.3

Fault localization techniques help locate faults in source codes by exploiting collected test information and have shown promising results. To precisely locate faults, the techniques require a large number of test cases that sufficiently exercise the executable statements together with the label information of each test case as a failure or a success. However, during the process of software development, developers may not have high-coverage test cases to effectively locate faults. With the test case generation techniques, a large number of test cases without expected outputs can be automatically generated. Whereas the execution results for generated test cases need to be inspected by developers, which brings much manual effort and potentially hampers fault-localization effectiveness. To address this problem, this paper presents a method to select a few test cases from a number of test cases without expected outputs for result inspection, and in the meantime selected test cases can still support effective fault localization. The experimental results show that our approach can significantly reduce the number of test cases that need to be inspected by developers and the effectiveness of fault localization techniques is close to that of whole test cases.

Enhanced Electrochemical Activity and Chromium Tolerance of the Nucleation‑Agent‑Free La2Ni0.9Fe0.1O4+δ Cathode by Gd0.1Ce0.9O1.95 Incorporation

Yihan Ling,Huixin Xie,Zijing Liu,Xiaoni Du,Hui Chen,Xuemei Ou,Ling Zhao,Riyan Achmad Budiman 대한금속·재료학회 2018 ELECTRONIC MATERIALS LETTERS Vol.14 No.4

For the sake of improving the electrochemical activity and chromium tolerance of the K2NiF4- type oxide, La2NiO4+ δ (LNO), with nonnucleation agents like Mn and Sr elements, the electrochemical performance and degradation were comparatively studied at two cathodes La2Ni0.9Fe0.1O4+ δ (LNF) and LNF-40wt%Gd0.1Ce0.9O1.95 (LNF-GDC) on the GDC electrolyte,where 5wt%Cr2O3 incorporation provides Cr-containing atmosphere. Compared with non-doped LNO, LNF shows a higherinterstitial oxygen concentration (δ = 0.298) and a lower electrical conductivity, where bivalent Ni ion, Ni×Ni , and trivalentNi ion, Ni⋅Ni , and trivalent Fe ion on Ni-site, Fe⋅Ni , were observed from the XPS measurements. LNF-GDC shows greatlyreduced interfacial polarization resistances (Rp), which are only half of those of LNF, indicating a better electrochemicalperformance. More importantly, no significant degradation of LNF-GDC in performance has been observed under exposureof Cr-containing atmosphere at 700 °C for 350 h, while Rp of LNF increased by nearly 20%, suggesting LNF by GDCincorporation can enhance the electrochemical performance as well as chromium tolerance for intermediate temperaturesolid oxide fuel cells (IT-SOFCs).

Selecting Test Cases for Result Inspection to Support Effective Fault Localization

Li, Yihan,Chen, Jicheng,Ni, Fan,Zhao, Yaqian,Wang, Hongwei Korean Institute of Information Scientists and Eng 2015 Journal of Computing Science and Engineering Vol.9 No.3

Fault localization techniques help locate faults in source codes by exploiting collected test information and have shown promising results. To precisely locate faults, the techniques require a large number of test cases that sufficiently exercise the executable statements together with the label information of each test case as a failure or a success. However, during the process of software development, developers may not have high-coverage test cases to effectively locate faults. With the test case generation techniques, a large number of test cases without expected outputs can be automatically generated. Whereas the execution results for generated test cases need to be inspected by developers, which brings much manual effort and potentially hampers fault-localization effectiveness. To address this problem, this paper presents a method to select a few test cases from a number of test cases without expected outputs for result inspection, and in the meantime selected test cases can still support effective fault localization. The experimental results show that our approach can significantly reduce the number of test cases that need to be inspected by developers and the effectiveness of fault localization techniques is close to that of whole test cases.

Research on Urban Traffic Optimal Path Planning Method based on Improved Genetic Algorithm

Xuejun Liu,Yihan Chen 보안공학연구지원센터 2016 International Journal of Smart Home Vol.10 No.10

The traditional genetic algorithm randomly selects nodes in two chromosomes for crossover operation, which may result in individuals of disconnected or loop circuit and lead to issues as meaningless crossover operations. In order to increase the diversity of the population and prevent the occurrence of premature mutation algorithm which might cause local convergence, this essay presents a new urban traffic optimal path planning method. Initialized from the improvement of population genetic algorithm, it designs the fitness function and optimizes crossover and mutation operators so that the optimal or near-optimal solution can be quickly figured out. Moreover, the Matlab software simulation test exhibits the feasibility and effectiveness of the method.

Development of Recombinase Polymerase Amplification Combined with Lateral Flow Strips for Rapid Detection of Cowpea Mild Mottle Virus

Xinyang Wu,Shuting Chen,Zixin Zhang,Yihan Zhang,Pingmei Li,Xinyi Chen,Miaomiao Liu,Qian Lu,Zhongyi Li,Zhongyan Wei,Pei Xu 한국식물병리학회 2023 Plant Pathology Journal Vol.39 No.5

Cowpea mild mottle virus (CPMMV) is a global plant virus that poses a threat to the production and quality of legume crops. Early and accurate diagnosis is essential for effective managing CPMMV outbreaks. With the advancement in isothermal recombinase polymerase amplification and lateral flow strips technologies, more rapid and sensitive methods have become available for detecting this pathogen. In this study, we have developed a reverse transcription recombinase polymerase amplification combined with lateral flow strips (RT-RPA-LFS) method for the detection of CPMMV, specifically targeting the CPMMV coat protein (CP) gene. The RT-RPA-LFS assay only requires 20 min at 40°C and demonstrates high specificity. Its detection limit was 10 copies/μl, which is approximately up to 100 times more sensitive than RT-PCR on agarose gel electrophoresis. The developed RT-RPA-LFS method offers a rapid, convenient, and sensitive approach for field detection of CPMMV, which contribute to controlling the spread of the virus.

Influence of burial conditions on the seepage characteristics of uranium bearing loose sandstone

Quan Jiang,Mingtao Jia,Yihan Yang,Qi Xu,Chuanfei Zhang,Xiangxue Zhang,Meifang Chen Korean Nuclear Society 2024 Nuclear Engineering and Technology Vol.56 No.4

To investigate the influence of different burial conditions on the seepage characteristics of loose sandstone in the leaching mining of sandstone uranium ore, this study applied different ground pressures and water pressures to rock samples at different burial depths to alter the rock's seepage characteristics. The permeability, pore distribution, and particle distribution characteristic parameters were determined, and the results showed that at the same burial depth, ground pressure had a greater effect on the reduction in permeability than water pressure. The patterns and mechanisms are as follows: under the influence of ground pressure, increasing the burial depth compresses the pores in the rock samples, decreases the proportion of effective permeable pores, and causes particle fragmentation, which blocks pore channels, resulting in a decrease in permeability. Under the influence of water pressure, increasing the burial depth expands the pores but also causes hard clay particles to decompose and block pore channels. As the burial depth increases, the particles eventually decompose completely, and the permeability initially decreases and then increases. In this experiment, the relationships between permeability and the proportion of pores larger than 0.15 ㎛ and the proportion of particles smaller than 59 ㎛ were found to be the most significant.

The synthesis of polyhydroxyalkanoates from low carbon wastewater under anaerobic-microaerobic process: effects of pH and nitrogen and phosphorus limitation

Kequan Zhang,Qian Fang,Yihan Xie,Yujia Chen,Tong Wei,Yanyu Xiao 대한환경공학회 2022 Environmental Engineering Research Vol.27 No.6

Polyhydroxyalkanoate (PHA) is a new type of bio-polyester which is expected to replace traditional petroleum-based plastics. The experiment was carried out based on anaerobic-microaerobic process. Firstly, the PHA accumulation capacity of activated sludge under different pH conditions was discussed, and then the batch test of nitrogen and phosphorus limitation was carried out under the condition of optimal pH. Moreover, the content of PHA monomer under nutrient restriction was also studied. The experimental results showed that when pH was not controlled (7.5~8.5), C:N and C:P weight ratio was equal to 150, the maximum content of PHA accounted for 50.39% and 36.07% of the dry cell weight, respectively. Besides, it was found that increasing the C:N weight ratio was beneficial to increasing the proportion of polyhydroxyvalerate (PHV) monomer in PHA.

Fatty acid-binding protein 5 activates cyclooxygenase-2 and promotes hypoxic injury in LO2 cells

Pan Long,Pang Yihan,Xiao Heng,Deng Xin,Chen Qingsong 대한독성 유전단백체 학회 2022 Molecular & cellular toxicology Vol.18 No.1

Background Hepatic hypoxia always results in liver inflammation and dysfunction. Fatty acid-binding protein 5 (FABP5) has been reported as a hypoxia-inducible gene and a regulator of inflammatory reaction . Objective To evaluate the effects of FABP5 on hypoxic liver injury and its potential mechanisms. Results FABP5 was hypoxia-inducible expression in liver tissues and LO2 cells. The expression levels of IL6 and TNFα were upregulated with the increasing expression of FABP5 in LO2 cells. Downregulation of FABP5 expression decreased the expression levels of ALT, AST and increased cell viability of hypoxic LO2 cells. Downregulation of FABP5 expression inhibited the cyclooxygenase-2/prostaglandin E2 (COX-2/PGE2) pathway and decreased inflammatory reaction in hypoxic LO2 cells. Conclusions FABP5 was shown to activate COX-2/PGE2 pathway and promote hypoxic injury in LO2 cells. FABP5 may be a potential target for the treatment of hypoxic liver injury.