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FPGA‑based real‑time simulation of LCC‑HVDC systems with C‑NAM method
Ruolan Li,Danyong Li,Yang Gao,Chen Gu,Xiaoyi Sun,Li Fan 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.6
The real-time simulation of a line-commutated converter-high voltage direct current (LCC-HVDC) system based on a field programmable gate array (FPGA) is proposed to meet the increasingly complex dynamic characteristics and real-time simulation requirements of HVDCs. In addition, a real-time simulation platform based on a CPU + FPGA is established forsimulation verification. First, a simulation model of the 12-pulse rectifier of an LCC-HVDC is established using the compact nodal analysis method (C-NAM). When compared with the traditional node analysis method, C-NAM reduces the number of multiplication executions in a single simulation step, and the degree of program serialization is signifi cantly reduced,which greatly improves the real-time simulation speed of a FPGA. Then, this simulation model is programmed in a FPGA, and the optimization algorithm further shortens the simulation step size. Finally, a 12-pulse LCC-HVDC is compared and verified with a 1 μs simulation step on a FPGA real-time simulation platform, and a simulation analysis verifies the accuracy of the model. This method can improve the simulation scale of an LCC-HVDC system, and enhance the versatility of the LCC-HVDC real-time simulator based on a FPGA.
Zhenlu Cai,Xiaoxuan Hu,Ruolan Tan,Yunran Feng,Meiqi Sun,Ning Ma,Xingxing Li,Li Huang,Jing An,Qian Ge,Haixia Lu 대한독성 유전단백체 학회 2019 Molecular & cellular toxicology Vol.15 No.4
Backgrounds: Previous studies were mainly focused on the effect of catechins and caffeine, the main pharmacological ingredients of green tea. However, the ordinary way of taking green tea is by drinking the tea water. Hence the benefits of water extractives of green tea were investigated in the current study. Methods: H2O2 was applied to induce the oxidative stress on PC12 cells. The neuroprotective effects of green tea against oxidative stress were determined by observing the biological behaviors of PC12 cells. Results: With the pre-treatment of light green tea, the survival and proliferation of oxidative stressed PC12 cells were significantly enhanced. H2O2 induced PC12 cell apoptosis was completely reversed. Consistently, the expression of JNK was up-regulated while the caspase-3 was down-regulated. Conclusion: These results suggested that drinking green tea, particularly the light green tea, performed neuroprotective effects against oxidative stress.
SEARCHES FOR MILLISECOND PULSAR CANDIDATES AMONG THE UNIDENTIFIED<i>FERMI</i>OBJECTS
Hui, C. Y.,Park, S. M.,Hu, C. P.,Lin, L. C. C.,Li, K. L.,Kong, A. K. H.,Tam, P. H. T.,Takata, J.,Cheng, K. S.,Jin, Ruolan,Yen, T.-C.,Kim, Chunglee IOP Publishing 2015 The Astrophysical journal Vol.809 No.1
<P>Here we report the results of searching millisecond pulsar (MSP) candidates from the Fermi LAT second source catalog (2FGL). Seven unassociated gamma-ray sources in this catalog are identified as promising MSP candidates based on their gamma-ray properties. Through the X-ray analysis, we have detected possible X-ray counterparts, localized to an arcsecond accuracy. We have systematically estimated their X-ray fluxes and compared them with the corresponding gamma-ray fluxes. The X-ray to gamma-ray flux ratios for 2FGL J1653.6-0159 and 2FGL J1946.4-5402 are comparable with the typical value for pulsars. For 2FGL J1625.2-0020, 2FGL J1653.6-0159, and 2FGL J1946.4-5402, their candidate X-ray counterparts are bright enough to perform a detailed spectral and temporal analysis to discriminate their thermal/non-thermal nature and search for the periodic signal. We have also searched for possible optical/IR counterparts at the X-ray positions. For the optical/IR source coincident with the brightest X-ray object associated with 2FGL J1120.0-2204, its spectral energy distribution is comparable with a late-type star. Evidence for the variability has also been found by examining its optical light curve. All the aforementioned 2FGL sources resemble a pulsar in one or more aspects, making them promising targets for follow-up investigations.</P>