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- 저자 : Quan Sun (검색결과 165 건)
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Prognostics of capacitors for power converters based on data augmentation and IPSO‑GRU
Quan Sun,Lichen Yang,Hongsheng Li,Guodong Sun 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.12
Aluminum electrolytic capacitors (AECs) play a crucial role in traction power electronic converters, which are also the most likely to be responsible for breakdowns. Fault prediction for AECs is helpful to realize preventive maintenance and to reduce the cost of the entire system. However, it is restricted by the collected data scale and the period of the deteriorative process of AECs. Thus, this paper takes the advantages of the synthetic minority oversampling technique (SMOTE) that is used to augment the degradation data information and the gate recurrent unit (GRU) that can be suitable for degradation samples to establish a prediction model. An improved particle swarm optimization (IPSO) algorithm is utilized to optimize the hyper parameters of the GRU to promote the feature learning and prediction performance. Thereupon, a prognostics model based on data augmentation and a GRU optimized by IPSO is simulated on a degradation dataset of AECs under an aging test. The results show that the integrated prediction model achieves better accuracy and reliability when compared to some traditional models. Furthermore, the relative error of each prediction point is less than 2.5% for single step and 3.0% for multi-step, respectively.
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Study on the Linkage Effect between China and South Korea Stock Market
Sun Jian quan,Sun Xiao lin,Chen Xiao long 한국유통과학회 2017 KODISA ICBE (International Conference on Business Vol.2017 No.-
As the trend of the world financial integration gradually strengthen, the research of the relationship between different stock markets mean a lot to improve the capital markets. The purpose of this article is to explore the linkage effect of market between China and South Korea. There is no evidence to prove that the five variables on behalf of the Chinese stock market have any relationship with KOSPI200 index by the granger causality test. There is no co-integration relationship between two markets by using co integration test to explore the long-term stable equilibrium relationship between China and South Korea stock markets. Therefore there is no significant relationship between China and South Korea market.
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Cross‑domain health status assessment of three‑phase inverters using improved DANN
Quan Sun,Fei Peng,Hongsheng Li,Jiacai Huang,Guodong Sun 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.9
Information and large number of fault labels are required to achieve intelligent health status assessment of three-phase inverters. However, the current signals of inverters cannot be sufficiently collected since open-circuit faults (OCFs) occur briefly, which makes it difficult to determine the OCF mode of the various power switches. A transfer learning model that effectively uses a small amount of sample data to achieve domain adaptation is proposed to address this problem. First, collected fault-sensitive signals are subjected to a continuous wavelet transform (CWT) to obtain two-dimensional image data with more abundant fault feature information. Second, the source domain and target domain features are projected into the same feature space through a domain adversarial neural network (DANN) to achieve multi-domain feature extraction and adaptation. Then, in the feature extraction module of the DANN, the deep residual network (Resnet) structure is used to replace the typical convolutional neural network (CNN) structure. Finally, an intelligent diagnosis network is used to identify the health status of the inverter samples under variable conditions. Experimental results show that the proposed model can accurately and effectively realize the cross-domain health assessment of three-phase inverters in the case of small samples. The accuracy of the proposed model is better than that of other classical transfer learning models.
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Yan Quan Sun,Colin Cole,Maksym Spiryagin 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.3
A rail vehicle-track interaction dynamics model has been applied to determine the track vertical dynamic forces due to rail short-wavelength dip defects such as squat, dip joints and welds, etc., which are required in both rail vehicle acceptance procedure and track maintenance. The model is validated using the field measurement data of rail squat defects and accelerations on a vehicle axlebox. The simulated track dynamic forces – the P2 forces due to rail dipped joints have been compared with those calculated by using a well-known formula. The results are compared and the formula’s limitations have been discussed. The dependence of the track vertical dynamic forces on the rail dip defect size and vehicle speed has also been investigated.
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Ziwei Sun,Qingtao Liu,Zhen Wang,Baobao Zhao,Quan Feng,Yanyan Sun,Min Zhong 한국고분자학회 2023 Macromolecular Research Vol.31 No.12
A hierarchical chitosan/polyvinyl alcohol/polyethylene glycol/nonwoven fabric (CS/PVA/PEG/NWF) micro/nanofiber composite membrane (CM) was prepared via electrospinning as a potential wound dressing. The polyester/viscose NWF acting as a substrate to receive the nanofiber layer was modified by alkali deweighting. Meanwhile, PEG with various additive amount was used to afford morphological regulation and control. As a result, the NWF modified with 7.5% NaOH solution exhibited a good hydrophilia and a superior dimensional stability based on smaller elongation at break and higher peel strength. In addition, the morphology of the nanofiber layer was closely related to PEG content. CS/PVA/PEG nanofiber with smaller diameter was spun when PEG content reached to 3.0%. Accordingly, the micro/nanofiber CM showed an opportune water absorption and good air permeability. Furthermore, neither hemolysis nor cytotoxicity phenomena appeared for the resultant CM, since the hemolysis rate and the cell viability were less than 5% and more than 70%, respectively.
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Study on the Influence of Population Aging on the Economic Development of Shandong Province
Jian quan Sun 한국유통과학회 2017 한국유통과학회 학술대회 논문집 Vol.2017 No.-
The change of population structure will inevitably have an impact on social and economic development, especially on the existing old-age security system and the labor market. This paper analyzed the economic development situation in Shandong province and the aging of the population, discussed the mechanism of the impact of population aging on economic development. By means of econometric analysis, this paper studied the mutual influence between population aging and economic growth in Shandong Province, and draw a conclusion that the aging population has a certain degree of slowing down effect on regional economic development. The aging of the population has a profound impact on the development of regional economy and its impact on regional economic development in the long run will be more obvious. In essence, population aging is not the ultimate decisive factor in economic development, but its regional economic development has a certain deceleration effect.
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Aerodynamic shape optimized design for wind turbine blade using new airfoil series
Quan Wang,Jun Wang,Jin Chen,Song Luo,Jinfeng Sun 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.7
This paper introduces a new airfoil series to optimize the aerodynamic shape of wind turbine blades. It is verified that the CQU-A airfoilseries exhibits high aerodynamic performance by using the wind tunnel experimental data and RFOIL. The geometry of a 2 MWwind turbine blade with new airfoil families is designed preliminarily based on the shape of Tjaereborg 2 MW rotor. A multi-objectiveoptimized model combining the maximum power coefficient of the wind turbine with minimum area of the blade surface is proposed forthe pitch regulated wind turbine. An optimized code is developed based on the corrected blade element momentum (BEM) theory andparticle swarm optimization (PSO) algorithm. The optimization results show that, compared with that of the original rotor and the Tjaereborgrotor, not only the power coefficient and annual power production is improved, but also the area of the blade surface is reduced. The decreased area indicates that the mass of the optimized blades is reduced. It is beneficial for increasing the fatigue life and reducingcost of composite materials if the internal structure of the wind turbine blades is unchanged. Furthermore, the load of the blade root iseffectively controlled by using this alternative optimization program.
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Quan, Bo,Lee, Chaedong,Yoo, Jung Sun,Piao, Yuanzhe Royal Society of Chemistry 2017 Journal of Materials Chemistry B Vol. No.
<P>Cancer nanomedicine involving nanotechnology-based drugs and <I>in vivo</I> imaging agents is an active field of nanoscience that provides new ways of enhancing therapeutic and diagnostic efficacy. Translating cancer nanomedicine mainly comes from rational and scalable design of nanoparticles to achieve versatile properties including specific size because nanomaterials whose properties confer unique advantages can only optimize clinical impact. Here, a facile scalable synthesis of highly monodisperse small silica nanoparticles was developed by screening various alkaline buffer solutions as catalysts. The size of silica nanoparticles ranging from 7 to 30 nm was finely controlled by varying the reaction temperature. Moderate sized silica nanoparticles in the range of 30 to 50 nm and large sized silica nanoparticles (>100 nm) were readily synthesized by <I>in situ</I> adding tetraethylorthosilicate (TEOS) and applying the Stöber method in the reaction solution using small silica nanoparticles as the seeds, respectively. Having shown the ability to precisely synthesize size controlled silica nanoparticles with a process compatible with good manufacturing practices, we performed <I>in vivo</I> fluorescence imaging and immunofluorescence analysis of sentinel lymph nodes (SLNs) with the synthesized nanoparticles having different sizes to investigate the size effect for effective identification of SLNs. The synthesized nanoparticles with a diameter of 12 nm showed effective SLN uptake within 10 min after intradermal injection both in noninvasive and in intraoperative imaging mode and were localized evenly inside the SLN, whereas the 120 nm sized nanoparticles failed to identify the SLN with noninvasive imaging at 10 min post-injection and distributed only in the medulla region not in the superficial cortex of the SLN. Taken together, a new facile scalable synthesis technique to achieve fine size controlling capability from very small silica nanoparticles (7 nm) was developed and it made possible to investigate the optimal size of nanoparticles for efficient SLN mapping which is still controversial.</P>
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( Sun Woo Lim ),( Kyung Woon Kim ),( Bo Mi Kim ),( Yoo Jin Shin ),( Kang Luo ),( Yi Quan ),( Sheng Cui ),( Eun Jeong Ko ),( Byung Ha Chung ),( Chul Woo Yang ) 대한내과학회 2022 The Korean Journal of Internal Medicine Vol.37 No.2
Background/Aims: Renal ischemia followed by reperfusion (I/R) is a leading cause of acute kidney injury (AKI), which is closely associated with high morbidity and mortality. Studies have shown that induced pluripotent stem cell (iPSC)-derived mesenchymal stem cells (iMSCs) exert powerful therapeutic effects in renal ischemia. However, the efficacy of iMSC-derived exosomes (iExo) on I/R injuries remains largely unknown. Methods: Human iPSCs were differentiated into iMSCs using a modified one-step method. Ultrafiltration, combined with purification, was used to isolate iExo from iMSCs. iExo was administered following I/R injury in a mouse model. The effect of iExo on I/R injury was assessed through changes in renal function, histology, and expression of oxidative stress, inflammation, and apoptosis markers. Further, we evaluated its association with the extracellular signal-regulated kinase (ERK) 1/2 signaling pathway. Results: Mice subjected to I/R injury exhibited typical AKI patterns; serum creatinine level, tubular necrosis, apoptosis, in flammatory cytokine production, and oxidative stress were markedly increased compared to sham mice. However, treatment with iExo attenuated these changes, significantly improving renal function and tissue damage, similar to the renoprotective effects of iMSCs on I/R injury. Significant induction of activated ERK 1/2 signaling molecules was observed in mice treated with iExo compared to those in the I/R injury group. Conclusions: The present study demonstrates that iExo administration ameliorated renal damage following I/R, suggesting that iMSC-derived exosomes may provide a novel therapeutic approach for AKI treatment.
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