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.

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.

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.

A Comparative Study of DEA-SFA for Industry-level in China

Zhen-Nan Kang,Tae-Hwang Kim 한국무역연구원 2018 貿易 硏究 Vol.14 No.3

This paper aims to make a comparative analysis between Data Envelopment Analysis (DEA) and Stochastic Frontier Analysis (SFA) based efficiency scores and decomposed TFP (Total Factor Productivity) index, which are estimated from constructed industry-level data in China from 1985 to 2014. On one hand, the results are that DEA and SFA efficiency scores appear positively correlated and estimated TFP growth is in similar shape. On the other hand, for industry-level productivity in China, we found that according to the SFA, the estimation of TFP change and all decomposed elements showed a less noisy and much smoother shape when compared to DEA. The paper concludes that for an analysis of TFP of Chinese industry, the methodology of an SFA is more effective in explaining the changes and impacts as compared to the DEA. Since most of China’s industry level productivity studies have been done using DEA, we expect different and more practically significant results for future inter-industry studies. In this context, this paper would contribute to develop analytic methodology of China’s industry level productivity studies.

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.

Dynamic Behavior of Rock Joint Under Different Impact Loads

Nan Wu,Zhen-de Zhu,Cong Zhang,Zhihua Luo 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.2

In order to investigate the influence of the rock joint to rock mass on dynamic loading, the Split Hopkinson Pressure Bar (SHPB) apparatus is used as an effective instrument. Using three different samples of intact (Series A), unfilled joint (Series B), and filled joint (Series C) interfaces, impact tests were performed under different impact speeds. Results showed that the peak strength of series B and C was 55%–75% that of series A. Series C was 10%–20% lower than series B because the former was filled with gypsum in the interface. The attenuation law of the transmission coefficient and failure mode caused by the rock joint was also obtained. To address the problem of classic rock joint constitutive relations being unsuitable under dynamic loading, a new regular expression is proposed by defining two velocity impact factors at respective impact velocities of 3.6 m/s, 6.6 m/s, and 9.6 m/s. Calculation results of this function are tested and verified, and the data are highly consistent.

Investigation on Properties of Rock Joint in Compression Dynamic Test

Nan Wu,Cong Zhang,Semaierjiang Maimaitiyusupu,Zhen-de Zhu 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.9

This paper is devoted to investigate rock joint interaction with stress waves by split Hopkinson pressure bar (SHPB) during wave propagation on dynamic loading. Taking two different specimens from the intact specimen (Series N) and the joint specimen (Series J),this study focused on three aspects: the influence of joint specimens on waveform propagation, inversion analysis of rock joint parameters using the waveform transmission coefficient, and the influence of the joint on rock specimens. With an increase in impact air pressure, compared with the intact sample, the transmittance and reflectance of joint specimens showed the opposite change rule; the closure rate change process of rock joint was converted from an exponential function to a linear function; the peak strength of the intact specimens was higher than the joint specimens at the same impact pressure above 19.58%, 21.21%, 21.56%, and 22.68% (mean values), respectively; and the strain rates (mean value) of the intact specimens were respectively 1.61, 1.31, 1.20, and 1.09 times that of the joint specimens.

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>

Prognostic Value of Serum AFP, AFP-L3, and GP73 in Monitoring Short-term Treatment Response and Recurrence of Hepatocellular Carcinoma after Radiofrequency Ablation

Wang, Nan-Ya,Wang, Cong,Li, Wei,Wang, Guan-Jun,Cui, Guo-Zhen,He, Hua,Zhao, Heng-Jun Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.4

Purpose: Alpha-fetoprotein (AFP), Lens culinaris agglutinin-reactive fraction of AFP (AFP-L3), and Golgi protein 73 (GP73) levels have been widely used as tumor markers for the diagnosis of hepatocellular carcinoma (HCC). The aim of this study was to investigate whether these tumor markers could be used to monitor short-term treatment response and recurrence of HCC in patients undergoing radiofrequency ablation (RFA). Methods: Between July 2012 and July 2013, 53 consecutive patients with newly diagnosed HCC were prospectively enrolled in this study. Among these, 32 patients underwent RFA, after which they were followed up prospectively at the First Hospital of Jilin University in China. Results: AFP, AFP-L3, and GP-73 values pre-RFA were not associated with tumor size, whereas AFP and GP-73 levels tended to be associated with tumor number, the presence of vascular invasion, deterioration of liver function, advanced-stage disease, and a poor performance status. GP-73 levels were dramatically elevated in the patients with hepatitis C-associated HCC. Neither pre-RFA nor 1-month post-RFA tumor marker values were associated with short-term outcome. The short-term recurrence rate of AFP-positive patients measured 1 month post-RFA was obviously higher than that of AFP-negative patients. Conclusions: AFP and GP-73 values were associated with clinical variables representing tumor growth and invasiveness, and the AFP value measured 1 month post-RFA was a strong predictor of short-term recurrence in patients with HCC.