Study of Harmonic Suppression of Ship Electric Propulsion Systems

Wang, Yifei,Yuan, Youxin,Chen, Jing The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.5

This paper studies the harmonic characteristics of ship electric propulsion systems and their treatment methods. It also adopts effective measures to suppress and prevent ship power systems from affecting ship operation due to the serious damage caused by harmonics. Firstly, the harmonic characteristics of a ship electric propulsion system are reviewed and discussed. Secondly, aiming at problems such as resonant frequency and filter characteristics variations, resonance point migration, and unstable filtering performances in conventional passive filters, a method for fully tuning of a passive dynamic tunable filter (PDTF) is proposed to realize harmonic suppression. Thirdly, to address the problems of the uncontrollable inductance L of traditional air gap iron core reactors and the harmonics of power electronic impedance converters (PEICs), this paper proposes an electromagnetic coupling reactor with impedance transformation and harmonic suppression characteristics (ECRITHS), with the internal filter (IF) designed to suppress the harmonics generated by PEICs. The ECRITHS is characterized by both harmonic suppression and impedance change. Fourthly, the ECRITHS is investigated. This investigation includes the harmonic suppression characteristics and impedance transformation characteristics of the ECRITHS at the fundamental frequency, which shows the good performance of the ECRITHS. Simulation and experimental evaluations of the PDTF are carried out. Multiple PDTFs can be configured to realize multi-order simultaneous dynamic filtering, and can effectively eliminate the current harmonics of ship electric propulsion systems. This is done to reduce the total harmonic distortion (THD) of the supply currents to well below the 5% limit imposed by the IEEE-519 standard. The PDTF also can eliminate harmonic currents in different geographic places by using a low voltage distribution system. Finally, a detailed discussion is presented, with challenges and future implications discussed. The research results are intended to effectively eliminate the harmonics of ship electric power propulsion systems and to improve the power quality of ship power systems. This is of theoretical and practical significance for improving the power quality and power savings of ship power systems.

Study of Harmonic Suppression of Ship Electric Propulsion Systems

Yifei Wang,Youxin Yuan,Jing Chen 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.5

This paper studies the harmonic characteristics of ship electric propulsion systems and their treatment methods. It also adopts effective measures to suppress and prevent ship power systems from affecting ship operation due to the serious damage caused by harmonics. Firstly, the harmonic characteristics of a ship electric propulsion system are reviewed and discussed. Secondly, aiming at problems such as resonant frequency and filter characteristics variations, resonance point migration, and unstable filtering performances in conventional passive filters, a method for fully tuning of a passive dynamic tunable filter (PDTF) is proposed to realize harmonic suppression. Thirdly, to address the problems of the uncontrollable inductance L of traditional air gap iron core reactors and the harmonics of power electronic impedance converters (PEICs), this paper proposes an electromagnetic coupling reactor with impedance transformation and harmonic suppression characteristics (ECRITHS), with the internal filter (IF) designed to suppress the harmonics generated by PEICs. The ECRITHS is characterized by both harmonic suppression and impedance change. Fourthly, the ECRITHS is investigated. This investigation includes the harmonic suppression characteristics and impedance transformation characteristics of the ECRITHS at the fundamental frequency, which shows the good performance of the ECRITHS. Simulation and experimental evaluations of the PDTF are carried out. Multiple PDTFs can be configured to realize multi-order simultaneous dynamic filtering, and can effectively eliminate the current harmonics of ship electric propulsion systems. This is done to reduce the total harmonic distortion (THD) of the supply currents to well below the 5% limit imposed by the IEEE-519 standard. The PDTF also can eliminate harmonic currents in different geographic places by using a low voltage distribution system. Finally, a detailed discussion is presented, with challenges and future implications discussed. The research results are intended to effectively eliminate the harmonics of ship electric power propulsion systems and to improve the power quality of ship power systems. This is of theoretical and practical significance for improving the power quality and power savings of ship power systems.

Novel Prognostic Nomograms Based on Inflammation-Related Markers for Patients with Hepatocellular Carcinoma Underwent Hepatectomy

Yifei Wang,Kaiyu Sun,Jingxian Shen,Bin Li,Ming Kuang,Qinghua Cao,Sui Peng 대한암학회 2019 Cancer Research and Treatment Vol.51 No.4

Purpose Hepatocellular carcinoma (HCC) is an aggressive disease with high recurrence rate. However, current staging systems were lack of predictive capacity for HCC recurrence. We aimed to develop prognostic nomograms based on inflammation-related markers for HCC patients underwent hepatectomy. Materials and Methods We recruited 889 surgically treated patients from two medical centers. Independent prognostic factors were identified by cox regression analyses. Nomograms for recurrence-free survival (RFS) and overall survival (OS) were established and validated internally and externally. The performance, discrimination, and calibration of nomograms were assessed and compared with existed staging systems. Results Neutrophil to lymphocyte ratio (NLR) and gamma-glutamyl transpeptidase to platelet ratio (GPR) were the two inflammation-related factor that independently correlated with survival. NLR, GPR, international normalized ratio (INR), microvascular invasion, satellite lesions, tumor number, tumor diameter, and macrovascular invasion were used to construct nomogram for RFS while GPR, total bilirubin, INR, -fetoprotein, microvascular invasion, satellite lesions, tumor diameter, and macrovascular invasion were for OS. In the training cohort, the C-index of nomogram was 0.701 (95% confidence interval [CI], 0.669 to 0.732) for RFS and 0.761 (95% CI, 0.728 to 0.795) for OS. These results received both internal and external validation with C-index of 0.701 (95% CI, 0.647 to 0.755) and 0.707 (95% CI, 0.657 to 0.756) for RFS, and 0.706 (95% CI, 0.640 to 0.772) and 0.708 (95%CI, 0.646 to 0.771) for OS, respectively. The nomograms showed superior accuracy to conventional staging systems (p < 0.001). Conclusion The nomograms based on inflammation-related markers are of high efficacy in predicting survival of HCC patients after hepatectomy, which will be valuable in guiding postoperative interventions and follow-ups.

Comparative transcriptome analysis of three chrysanthemums provides insights into flavonoid and terpenoid biosynthesis

Wang Xu,Zhang Jingjing,Liu Zhige,Wang Shuaibin,Huang Bisheng,Hu Zhigang,Liu Yifei 한국식물학회 2021 Journal of Plant Biology Vol.64 No.5

Chrysanthemum indicum var. aromaticum is an important resource plant for breeding excellent aromatic varieties of ornamental and medicinal chrysanthemums. However, the biosynthesis and regulation mechanisms of typically aromatic ingredients in C. indicum var. aromaticum are poorly understood, which restricted the utilization of this plant. Here, the transcriptome of C. indicum var. aromaticum was investigated and comparative analysis was conducted with the other two closely related chrysanthemum taxa C. indicum and C. nankingense. The global transcriptome profiles showed clear difference of gene expression patterns between the three chrysanthemums, of which 52 flavonoid biosynthesis-associated genes, 157 transcription factors, and 24 flavonoid Uridine diphosphate (UDP) -glucuronosyl and -glucosyltransferase genes were significantly differentially expressed. Furthermore, 22 differential expression genes (DEGs) in relation to the terpenoid backbone biosynthesis and 183 DEGs related to terpenoid diversification were identified. Of which, 14 genes involved into TS/CYP gene cluster showed higher expression in CIA than those in CI or CN. These results increased our understanding of flavonoid diversification and aromatic ingredients accumulation in plants, and will also help improve resource conservation and sustainable utilization of the important resource plant C. indicum var. aromaticum.

Comparative transcriptome analysis of salt-sensitive and salt-tolerant maize reveals potential mechanisms to enhance salt resistance

Mingquan Wang,Yufeng Wang,Yifei Zhang,Chunxia Li,Shichen Gong,Shuqin Yan,Guoliang Li,Guanghui Hu,Honglei Ren,Jianfei Yang,Tao Yu,Kejun Yang 한국유전학회 2019 Genes & Genomics Vol.41 No.7

Background Salt stress is a devastating environmental stress that causes plant growth inhibition and yield reduction. Objective The identification of salt-tolerant genes brings hope for the generation of salinity-tolerant crop plants through molecular breeding. Methods In this study, one salt-sensitive and one salt-tolerant maize inbred line were screened from 242 maize inbred lines. Reactive oxygen species (ROS)-related enzyme activities were detected and salt-responsive comparative transcriptome analysis was performed for control and 220 mM NaCl treated maize leaves. Results Salt-tolerant maize inbred line (L87) showed higher ROS-related enzyme (SOD, POD, APX and CAT) activities and accumulated relatively lower levels of ROS under salt stress. Of the total DEGs, 1856 upregulated DEGs were specific to L87, including stress tolerance-related members of the 70kDa family of heat shock proteins (Hsp70s) and aquaporins. The DEGs involved in the abscisic acid (ABA), ethylene, jasmonic acid (JA) and salicylic acid (SA) signal transduction pathways may determine the difference in salt tolerance between the two varieties, especially one central component SnRK2, that positively regulates ABA signaling and was only upregulated in L87. Analysis of DEGs related to ROS scavenging showed that some peroxidase (POD), glutathione S-transferase (GST), catalase (CAT) and superoxide dismutase (SOD) genes specific to L87 probably enhanced its salt tolerance. The analysis of differentially expressed transcription factors (TFs) suggested that WRKY TFs could contribute to the difference in salt tolerance between the two maize lines. Conclusion Compared with Salt-sensitive maize inbred line (L29), L87 exhibits specific regulatory mechanisms related to salt tolerance, including plant hormone interactions, ROS scavenging and the regulation of TFs. Our study identifies new candidate genes that may regulate maize tolerance to salt stress and provides useful information for breeding maize with high salt resistance.

Effects of chronic alcohol exposure on ischemia–reperfusion-induced acute kidney injury in mice: the role of β-arrestin 2 and glycogen synthase kinase 3

Lihua Wang,Yifei Zhu,Lili Wang,Jingjing Hou,Yongning Gao,Lei Shen,Jingyu Zhang 생화학분자생물학회 2017 Experimental and molecular medicine Vol.49 No.-

Little is known about the effects of chronic alcohol intake on the outcome of acute kidney injury (AKI). Hence, we examined the effects of chronic alcohol intake on the development of renal fibrosis following AKI in an animal model of bilateral renal ischemia–reperfusion (IR) injury. We first found that chronic alcohol exposure exacerbated bilateral IR-induced renal fibrosis and renal function impairment. This phenomenon was associated with increased bilateral IR-induced extracellular matrix deposition and an increased myofibroblast population as well as increased bilateral IR-induced expression of fibrosis-related genes in the kidneys. To explore the mechanisms underlying this phenomenon, we showed that chronic alcohol exposure enhanced β-arrestin 2 (Arrb2) expression and Akt and glycogen synthase kinase-3 (GSK3)β activation in the kidneys. Importantly, pharmacological GSK3 inhibition alleviated bilateral IR-induced renal fibrosis and renal function impairment. Furthermore, we demonstrated that Arrb2− / − mice exhibited resistance to IR-induced renal fibrosis and renal function impairment following chronic alcohol exposure, and these effects were associated with attenuated GSK3β activation in the kidneys. Taken together, our results suggest that chronic alcohol exposure may potentiate AKI via β-arrestin 2/Akt/GSK3β-mediated signaling in the kidney.

쇼핑몰의 예술적 요소와 방문목적이 방문의도에 미치는 영향

왕이페이(Wang Yifei),신형덕(Shin, Hyung-Deok),박주연(Park, Joo-Yeon) 한국상품학회 2020 商品學硏究 Vol.38 No.3

제품이나 서비스가 가진 예술적 요소는 다른 특성들과 더불어 경쟁력의 원천으로 부상하고 있다. 특히 경쟁이 심화되고 있는 오프라인 쇼핑몰 산업에서는 소비자에게 주목받는 경쟁요소에 대한 연구의 중요성이 부각된다. 본 연구는 쇼핑몰 방문의도에 있어서 예술적 요소의 영향력을 밝히고자 하였다. 이에 본 연구는 가상으로 설정된 쇼핑몰의 잠재적 방문자가 예술적 요소를 인지하는 경우 쇼핑몰 방문의도에 긍정적으로 반응하는가에 대해 실증 분석하였다. 동일한 쇼핑몰 사진에 대해 기술하는 방식에 있어서 예술적 요소를 조작적으로 표현한 건축, 조각, 공간적 가치를 부여하는 설문지와 비예술적 요소인 안전, 교육, 경제적 가치를 표현하는 설문지에 대해 대조군의 응답을 비교하는 방법으로 144명의 설문 응답에 대한 회귀분석을 수행한 결과, 예술적 요소가 포함된 것으로 기술된 쇼핑몰에서 더 높은 방문의도를 발견했다. 또한 예술적 요소와 방문의도의 관계에 있어서 응답자가 평소에 쇼핑몰을 방문하는 목적은 유의한 조절효과를 갖는 것으로 나타났다. 본 연구결과는 소비자가 쇼핑몰을 선택함에 있어서 상품의 품질과 점포의 다양성 등 물리적인 요소가 중요하다는 기존 연구 결과를 확장하여 예술적 가치가 있는 설치물이나 거리 공연 등이 실제로 쇼핑몰 방문의도에 영향을 미칠 수 있다는 사실은 고객의 방문이 경쟁력의 중요한 원천인 다양한 매장에 있어서의 마케팅 전략에 시사점을 던진다. Artistic elements are emerging as a source of competitive advantage of products or services, among various types of physical characteristics. Especially, as the level of competition increases in a shopping mall industry, artistic elements can be important differentiating tools to catch attention to visitors. This study investigated the effects of artistic elements on intention to visit of customers. To do this, we prepared two types of survey which have the same picture of an artificial shopping mall but different descriptions of the picture, where one described artistic elements in the picture so that respondents can recognize them, and the other described in other ways for the same picture, and investigated if this difference of descriptions makes different levels of intention to visit of respondents. Moreover, we investigated if the purpose of visit to a shopping mall has a moderating effect in the relationship between recognized artistic elements and intention to visit. Using 144 survey responds of graduate and undergraduate college students, we found that recognized artistic elements in a shopping mall increase intention to visit, and social purpose of mall visit negatively moderates the relationship. This study confirms the existence of artistic elements can attract people to a shopping mall and be a source competitive advantage.

Human Amnion-Derived Mesenchymal Stem Cells Protect Human Bone Marrow Mesenchymal Stem Cells against Oxidative Stress-Mediated Dysfunction via ERK1/2 MAPK Signaling

Wang, Yuli,Ma, Junchi,Du, Yifei,Miao, Jing,Chen, Ning Korean Society for Molecular and Cellular Biology 2016 Molecules and cells Vol.39 No.3

Epidemiological evidence suggests that bone is especially sensitive to oxidative stress, causing bone loss in the elderly. Previous studies indicated that human amnion-derived mesenchymal stem cells (HAMSCs), obtained from human amniotic membranes, exerted osteoprotective effects in vivo. However, the potential of HAMSCs as seed cells against oxidative stress-mediated dysfunction is unknown. In this study, we systemically investigated their antioxidative and osteogenic effects in vitro. Here, we demonstrated that HAMSCs significantly promoted the proliferation and osteoblastic differentiation of $H_2O_2$-induced human bone marrow mesenchymal stem cells (HBMSCs), and down-regulated the reactive oxygen species (ROS) level. Further, our results suggest that activation of the ERK1/2 MAPK signal transduction pathway is essential for both HAMSCs-mediated osteogenic and protective effects against oxidative stress-induced dysfunction in HBMSCs. U0126, a highly selective inhibitor of extracellular ERK1/2 MAPK signaling, significantly suppressed the antioxidative and osteogenic effects in HAMSCs. In conclusion, by modulating HBMSCs, HAMSCs show a strong potential in treating oxidative stress- mediated bone deficiency.

Nitrogen-doped graphene forests as electrodes for high-performance wearable supercapacitors

Wang, Mei,Ma, Yifei Elsevier 2017 ELECTROCHIMICA ACTA Vol.250 No.-

<P><B>Abstract</B></P> <P>Recently, a graphene forest (GF) is synthesized by a plasma enhanced chemical vapor deposition (PECVD) process, which subverts the stereotyped morphology of vertical graphene. The GF is demonstrated to possess excellent performance in flexible and bendable electrical double-layer capacitors (EDLCs). In this work, synthesis process of the GF has been optimized and N-doped GF is successfully achieved by introducing NH<SUB>3</SUB> as the nitrogen precursor during the PECVD process. The N-doping obviously affects the morphology of the GF and the in-plane conductivity of GF is desirably enhanced. The specific area capacitances and volumetric capacitances of N-doped GF-based EDLC increases 26% and 89% in average, respectively, at different current densities compared with the non-doped GF-based EDLC. In addition, both the energy and power densities are improved, and impressively, the energy densities improve 87% by the N-doping of GF electrodes. The GF-based EDLC also provides the desirable stability that no degradation can be observed within 10,000 cycles. Finally, the flexible N-doped GF-based EDLC is also tested as a wearable supercapacitor, exhibiting no capacitance decrease under the dynamic bending situation. Our approach to synthesize the N-doped GF electrodes can achieve the fine-scale nano-structured GF electrodes and provide a new way forward for improved energy storage devices.</P> <P><B>Highlights</B></P> <P> <UL> <LI> N-doped graphene forest (GF) is successfully synthesized by in-situ PECVD process. </LI> <LI> Morphology of N-doped GF electrode realizes a better in-plane electron transfer. </LI> <LI> Areal and volumetric capacitances increase 26% and 89% by the N-doping of GF. </LI> <LI> Energy and power densities increase 87% and 50% by the N-doping of GF. </LI> <LI> The N-doped GF-based EDLC shows excellent bendability and reliable durability. </LI> </UL> </P>

Semisupervised Tripled Dictionary Learning for Standard-Dose PET Image Prediction Using Low-Dose PET and Multimodal MRI

Wang, Yan,Shen, Dinggang,Ma, Guangkai,An, Le,Shi, Feng,Zhang, Pei,Lalush, David S.,Wu, Xi,Pu, Yifei,Zhou, Jiliu IEEE 2017 IEEE Transactions on Biomedical Engineering Vol.64 No.3

<P>Objective: To obtain high-quality positron emission tomography (PET) image with low-dose tracer injection, this study attempts to predict the standard-dose PET (S-PET) image from both its low-dose PET (L-PET) counterpart and corresponding magnetic resonance imaging (MRI). Methods: It was achieved by patch-based sparse representation (SR), using the training samples with a complete set of MRI, L-PET and S-PET modalities for dictionary construction. However, the number of training samples with complete modalities is often limited. In practice, many samples generally have incomplete modalities (i.e., with one or two missing modalities) that thus cannot be used in the prediction process. In light of this, we develop a semisupervised tripled dictionary learning (SSTDL) method for S-PET image prediction, which can utilize not only the samples with complete modalities (called complete samples) but also the samples with incomplete modalities (called incomplete samples), to take advantage of the large number of available training samples and thus further improve the prediction performance. Results: Validation was done on a real human brain dataset consisting of 18 subjects, and the results show that our method is superior to the SR and other baseline methods. Conclusion: This paper proposed a new S-PET prediction method, which can significantly improve the PET image quality with low-dose injection. Significance: The proposed method is favorable in clinical application since it can decrease the potential radiation risk for patients.</P>