Effect of Shifting the Pole-shoe and Damper-bar Centerlines on the No-load Voltage Waveform of a Tubular Hydro-generator

Fan, Zhen-nan,Han, Li,Liao, Yong,Xie, Li-dan,Wen, Kun,Wang, Jun,Dong, Xiu-cheng,Yao, Bing The Korean Institute of Electrical Engineers 2018 Journal of Electrical Engineering & Technology Vol.13 No.3

This study optimises the no-load voltage waveform of tubular hydro-generators by a simple design scheme. For different centerlines of the pole shoe and damper bar, the optimisation effects on the no-load voltage waveform are investigated in two tubular hydro-generators with different weighted powers (34 MW and 18 MW). The results are compared with those of the traditional stator-slots skewed design. The quality of the no-load voltage waveform was related to the shifting degree, and the different optimisation effects between the integer slot generator (q = 2) and the fractional slot generator (q = 11/2) were analysed. This research can improve the quality of the power output and no-load voltage waveform, and provide an effective reference for improving the industrial design and manufacture level of tubular hydro-generators.

Study on Leading-phase Operation Capability of a 770 MW Jumbo Hydro-generator based on Stability Analysis and End-Region Heat Analysis

Fan, Zhen-nan,Zhou, Zhi-ting,Li, Jian-fu,Wen, Kun,Wang, Jun,Sun, Zhang,Wang, Tao,Yao, Bing The Korean Institute of Electrical Engineers 2018 Journal of Electrical Engineering & Technology Vol.13 No.3

A generator-grid coupling calculation model is established to study the leading-phase operational capability of a 770 MW jumbo hydro-generator in a Chinese ultra-mega hydropower station. The static and dynamic stability of the generator are analyzed and calculated to obtain stability limits under leading-phase operating conditions. Three-dimensional (3D) time-varying nonlinear moving electromagnetic and temperature field models of the generator end-region are also established and used to determine the magnetic field, loss, and temperature of the end-region under the leading-phase operating condition. The simulation results agree with data measured from the actual 770 MW hydro-generator. This paper provides reliable reference data for the leading-phase operation of a jumbo hydro-generator, which will help to improve in the design and manufacture of future hydro-generators.

Effect of Shifting the Pole-shoe and Damper-bar Centerlines on the No-load Voltage Waveform of a Tubular Hydro-generator

Zhen-nan Fan,Li Han,Yong Liao,Li-dan Xie,Kun Wen,Jun Wang,Xiu-cheng Dong,Bing Yao 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.3

This study optimises the no-load voltage waveform of tubular hydro-generators by a simple design scheme. For different centerlines of the pole shoe and damper bar, the optimisation effects on the no-load voltage waveform are investigated in two tubular hydro-generators with different weighted powers (34 MW and 18 MW). The results are compared with those of the traditional stator-slots skewed design. The quality of the no-load voltage waveform was related to the shifting degree, and the different optimisation effects between the integer slot generator (q = 2) and the fractional slot generator (q = 11/2) were analysed. This research can improve the quality of the power output and no-load voltage waveform, and provide an effective reference for improving the industrial design and manufacture level of tubular hydro-generators.

Study on Leading-phase Operation Capability of a 770 MW Jumbo Hydro-generator based on Stability Analysis and End-Region Heat Analysis

Zhen-nan Fan,Zhi-ting Zhou,Jian-fu Li,Kun Wen,Jun Wang,Zhang Sun,Tao Wang,Bing Yao 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.3

A generator-grid coupling calculation model is established to study the leading-phase operational capability of a 770 MW jumbo hydro-generator in a Chinese ultra-mega hydropower station. The static and dynamic stability of the generator are analyzed and calculated to obtain stability limits under leading-phase operating conditions. Three-dimensional (3D) time-varying nonlinear moving electromagnetic and temperature field models of the generator end-region are also established and used to determine the magnetic field, loss, and temperature of the end-region under the leading-phase operating condition. The simulation results agree with data measured from the actual 770 MW hydro-generator. This paper provides reliable reference data for the leading-phase operation of a jumbo hydro-generator, which will help to improve in the design and manufacture of future hydro-generators.

Ecofriendly high-performance ionic soft actuators based on graphene-mediated cellulose acetate

Nan, Minghui,Wang, Fan,Kim, Seokjae,Li, Hao,Jin, Zhen,Bang, Doyeon,Kim, Chang-Sei,Park, Jong-Oh,Choi, Eunpyo Elsevier 2019 Sensors and actuators. B Chemical Vol.301 No.-

<P><B>Abstract</B></P> <P>Ionic-type artificial muscles with eco-friendly, biodegradable, and biocompatible functionalities have attracted attention for a wide range of potential applications in wearable electronics, soft haptic-feedback systems, and active biomedical devices. Here, we report on the development of an ecofriendly high-performance ionic soft actuator based on biofriendly cellulose acetate (CA), graphene nanopowders (GN), ionic liquid (IL) as a plasticizer, and biofriendly-flexible-nonmetallic conducting polymer poly(3,4-ethylene-dioxythiopene)-polystyrenesulfonate (PEDOT: PSS) as an electrode, thereby realizing a novel ecofriendly CA-IL-GN actuator with a large bending mechanical deformation and a fast response time. The proposed CA-IL-GN (0.2 wt%) nanocomposite membrane exhibited dramatic increments in specific capacitance (2.92 times) and Young’s modulus (2.38 times), thus leading to a 2.9 times larger bending deformation and a 4.8 times faster response than those of pure CA-IL actuator. Therefore, the developed ecofriendly high-performance CA-IL-GN actuator can be considered to be a promising candidate for human-friendly electronics, including artificial muscles, flexible haptic devices, soft wearable devices, and bio-medical devices, due to its cost-effectiveness, large bending mechanical actuation, fast response, and bio-friendly functionalities.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ecofriendly soft actuator based on cellulose acetate, graphene nanopowders, ionic liquid as plasticizer, and PEDOT:PSS as soft electrode. </LI> <LI> Proposed membrane exhibited increments in specific capacitance and Young’s modulus compare with a pure cellulose acetate actuator. </LI> <LI> Proposed actuator showed a 2.9 times larger bending deformation and a 4.8 times faster response than those of pure cellulose acetate actuator. </LI> </UL> </P>

Undaria Pinnatifida Suppresses Nasal Inflammation via Inhibiting Eosinophil and Mast Cell Activation

Zhen Nan Yu,Chang Ho Song,Thi Van Nguyen,Juan Jin,Eui Hyeog Han,Yan Jing Fan,Hyoung Tae Kim,Ok Hee Chai 대한체질인류학회 2021 대한체질인류학회 학술대회 연제 초록 Vol.64 No.-

Undaria pinnatifida (U. pinnatifida), a brown alga commonly grown in the oceans of East Asia, has long been a part of human diet and medicine. Though U. pinnatifida has been reported to have immunomodulatory, anti-inflammatory, anti-oxidant, anti-diabetic and anti-bacterial activities, its specific effect on allergic rhinitis (AR) disease has not been clarified. In this study, the anti-allergic and anti-inflammatory effects of U. pinnatifida extract (UPE) were investigated in a mouse model of ovalbumin (OVA)-induced AR. After UPE treatment, the nasal and lung allergy symptoms, nasal mucosal swelling, and goblet cell hyperplasia were obviously ameliorated. Oral UPE regulated the balance of T helper (Th) 1/Th2 and Th17/Treg cells differentiation in AR mice in a dose-dependent manner. Accordingly, UPE attenuated the expression of Th2 cytokines (IL-4, IL-5, IL-13), Th17-related cytokine IL-17, proinflammatory cytokines (TNF-α, IL-6) and up-regulated the secretion of Th1 and Treg cytokines including IL-12, IFN-γ and IL-10 in nasal lavage fluid (NALF). Also, UPE attenuated the migration of eosinophils to the nasal mucosa and NALF by inhibiting eotaxin, an eosinophil-specific chemoattractant, as well as suppressed Nuclear factor-kappaB (NF-κB)/Signal transducer and activator of transcription 3 (STAT3), a signaling pathway in eosinophils. The levels of anti-OVA specific IgE and IgG1 were decreased, and as a result, the allergic response was attenuated by UPE via inhibiting mast cells accumulation in nasal mucosa. These results suggested that UPE may have therapeutic potential for treating AR through modulating important immune cells in the immune system such as Th1/Th2 and Th17/Treg balance, eosinophils and mast cells.

Caffeine ameliorates allergic rhinitis in an ovalbumin-induced murine model

Yan Jing Fan,Eui Hyeog Han,Hyoung Tae Kim,Zhen Nan Yu,Thi Van Nguyen,Juan Jin,Ok Hee Chai,Changho Song 대한체질인류학회 2021 대한체질인류학회 학술대회 연제 초록 Vol.64 No.-

Caffeine is one of the most widely consumed pharmacologically active products worldwide. Caffeine exhibits various pharmacological activities in central nervous, cardiovascular, and respiratory systems. Additionally, caffeine exhibited anti-inflammatory effects in lipopolysaccharide-challenged rats. However, the potential anti-inflammatory activity of caffeine in allergic rhinitis (AR) has not been investigated yet. Therefore, we aimed to examine the anti-allergic effects of caffeine in ovalbumin (OVA)-induced AR mice in this study. Briefly, BALB/c mice were sensitized and challenged with OVA. Caffeine (5, 10, 20 mg/kg) and dexamethasone (Dex, 2.5 mg/kg) were treated by intranasal instillation of 20 µL/nasal cavity for 13 days. In this study, caffeine attenuated the nasal symptoms, including rubbing and sneezing. Caffeine ameliorated the inflammation in the lungs. In addition, caffeine reduced the thickness of the nasal mucosa, alleviated goblet cell hyperplasia and reduced mast cell recruitment in the nasal mucosa. Caffeine decreased OVA-specific immunoglobulin (Ig) E and IgG1 levels in the serum, whereas increased the level of OVA-specific IgG2a. Caffeine also reduced T helper (Th) 2 cytokines (interleukin(IL)-4, IL-5 and IL-13) and Th17 family related factors (IL-17, IL-6, retinoic-related orphan receptor gamma, signal transducer and activator of transcription-3 and phospho-signal transducer and activator of transcription-3) levels and elevated Th1 cytokines (IL-12 and interferon gamma) levels in the nasal lavage fluid. However, the level of malondialdehyde was down-regulated, the levels of superoxide dismutase, nuclear factor erythroid 2-related factor 2 and heme oxygenase-1 were up-regulated in the caffeine treatment. Collectively, we suggest that caffeine might have therapeutic effects on AR.

Anti-allergic Effects of Caffeine in an Allergic Rhinitis Mouse Model

Yan Jing Fan,Chun Hua Piao,Thi Van Nguyen,Zhen Nan Yu,Ok Hee Chai,Chang Ho Song 대한체질인류학회 2020 대한체질인류학회지 Vol.33 No.1

Caffeine (1, 3, 7-trimethylxanthine) is one of the most widely consumed pharmacologically active products worldwide. Caffeine exhibits various pharmacological activities in central nervous, cardiovascular, and respiratory systems. Additionally, caffeine exhibited anti-inflammatory effects in lipopolysaccharide-challenged rats. However, to our knowledge, the potential anti-inflammatory activity of caffeine in allergic rhinitis (AR) has not yet been investigated. Therefore, in this study, we aimed to examine the anti-allergic effects of caffeine in ovalbumin (OVA)-induced AR in mice. We showed that caffeine attenuated the nasal symptoms, including rubbing and sneezing. It reduced the thickness of the nasal mucosa and alleviated goblet cell hyperplasia in the nasal mucosa. In addition, caffeine ameliorated the inflammation in the lungs and decreased OVA-specific immunoglobulin E (IgE) and IgG1 levels in the serum. It also reduced T helper type 2 (Th2) cytokine (interleukin (IL)-4 and IL-5) levels and elevated Th1 cytokine (IL-12 and IFN-γ) levels in the nasal lavage fluid. Collectively, we suggest that caffeine might have therapeutic effects in AR owing to its anti-inflammatory activities.

Analysis and Correction of Through-bolt End-region Overheating and Breakdown Failure in a Large Tubular Hydro-generator

Zhi-ting Zhou,Zhen-nan Fan,Jian-fu Li,Kun Wen,Bide Zhang,Tao Wang,Yan-kun Xia,Zhang Sun,Bing Yao 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.6

A field-circuit coupling model of a typical faulty generator is established to correct through-bolt end-region overheating and breakdown failure in a tubular hydro-generator. Using the model, eddy current loss and electromagnetic forces on through bolts under normal and failure conditions are analyzed and compared and the natural frequency of a through bolt is determined. Based on the analysis results, the causative mechanism of failure is revealed and targeted improvement design measures are proposed. The numerical results are found to be consistent with the actual fault characteristics, validating the design measure improvements. The results are useful in improving the design and manufacturing standards and enhancing the operational reliability of large tubular hydrogenerators.

Analysis and Correction of Through-bolt End-region Overheating and Breakdown Failure in a Large Tubular Hydro-generator

Zhou, Zhi-ting,Fan, Zhen-nan,Li, Jian-fu,Wen, Kun,Zhang, Bide,Wang, Tao,Xia, Yan-kun,Sun, Zhang,Yao, Bing The Korean Institute of Electrical Engineers 2018 Journal of Electrical Engineering & Technology Vol.13 No.6

A field-circuit coupling model of a typical faulty generator is established to correct through-bolt end-region overheating and breakdown failure in a tubular hydro-generator. Using the model, eddy current loss and electromagnetic forces on through bolts under normal and failure conditions are analyzed and compared and the natural frequency of a through bolt is determined. Based on the analysis results, the causative mechanism of failure is revealed and targeted improvement design measures are proposed. The numerical results are found to be consistent with the actual fault characteristics, validating the design measure improvements. The results are useful in improving the design and manufacturing standards and enhancing the operational reliability of large tubular hydro-generators.