FEM Simulation and Test Verification of PD Ultrasonic Signal Propagation in a Power Transformer Model

Zan Wang,Chaofei Gao,Liwei Zheng,Jikun Ren,Wei Wang,Yushuai Zhang,Shijie Han 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.1

Ultrasonic signals will be generated when partial discharge occurs in internal insulation faults in large oil immersed power transformers: because the ultrasonic signal has strong anti-interference ability and has no direct electromagnetic contact with the equipment, it is widely used in transformer fault detection and positioning. In this paper, the fi nite element method (FEM) is used to simulate the ultrasonic signal in a 35 kV power transformer. The infl uence of transformer case on ultrasonic signal propagation is considered, and the propagation law of the ultrasonic signal inside the transformer is obtained. Fabry–Pérot (F–P) fi bre acoustic sensors with a centre frequency of 28 kHz were fabricated. A partial discharge detection test was carried out in a 35 kV transformer winding model using the F–P sensors. The test results show that the ultrasonic waveform detected by the F–P sensors are in good agreement with the simulation results, and the propagation of the ultrasonic wave inside the transformer is verifi ed. It lays a foundation for detecting and locating PDs in power transformer by F–P acoustic sensors.

Transmission Characteristics of Indoor Infrared Diffuse Links Employing Three-Beam Optical Transmitters and Non-Imaging Receivers

Zan Wang(왕잔),Jae Kyung Pan(반재경) 한국통신학회 2008 韓國通信學會論文誌 Vol.33 No.12A

Diffuse wireless optical communication offers more robust optical links in terms of coverage and shadowing than line-of-sight links. However, traditional diffuse wireless infrared (IR) transceiver systems are more susceptible to multi-path distortion and great power decrease, which results in limiting high-speed performance. Multi-beam is an effective technique to compensate for multi-path distortion in a wireless infrared environment. The goal of this paper is to analyze the transmission characteristics by replacing traditional diffuse system (TDS) which contains single wide angle transmitter and single element receiver by system consisting of three-beam transmitter and non-imaging receiver (TNS) attached with compound parabolic concentrator (CPC). In the simulation, we use the recursive model developed by Barry and Kahn and build the scenario based on 10 different cases which have been listed in Table 1. Moreover, we also check the reliability of the TNS diffuse link channel by BER test on the basis of different receiver positions and room sizes. The simulation results not only show the basic transmission characteristics of TNS diffuse link, but also are references to design more efficient and reliable indoor infrared transmission systems.

Research on Partial Discharge Pattern Recognition in GIS Based on EFPI Sensor

Wang Zan,Liu Zhongquan,Qiao Lili,Qian Dingdong,Chen Zhongxian,Gao Chaofei,Wang Wei 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.1

An EFPI fber optic ultrasonic sensor can be used for the detection and pattern recognition of partial discharge ultrasonic signals in Gas Insulated Switchgear. Compared with traditional piezoelectric sensors, it has many advantages, such as high sensitivity and strong anti-interference ability. Based on this, four typical PD models of the tip, metal particles, suspension and creeping surface were set up in the GIS cavity flled with 0.4 MPa SF6 gas, and the EFPI sensor was innovatively used to detect the discharge ultrasonic signal and extract the single ultrasonic pulse signal. The waveform features form a feature parameter database, and the probabilistic neural network algorithm and the support vector machine algorithm are used for pattern recognition and comparative analysis, respectively. The ultrasonic signal detected by the EFPI sensor has prominent features. On the basis of extracting the feature parameters, the two pattern recognition algorithms can achieve an average recognition rate of more than 85%, and the recognition efect of the support vector machine is better than that of the probabilistic neural network

ANALYSIS ON MEMBRANE HEAT EXCHANGER APPLIED TO ABSORPTION CHILLER

ZAN-SHE WANG,ZHAO-LIN GU,GUO-ZHENG WANG,FENG CUI,SHI-YU FENG 대한설비공학회 2011 International Journal of Air-Conditioning and Refr Vol.19 No.3

A novel membrane heat exchanger was proposed and analyzed. It was expected that the novel heat exchanger could be applied to the lithium bromide absorption chiller. Polyvinylidene fluoride hollow fiber module was adopted as the solution heat exchanger. The hot feed solution from the generator flowed into the lumen side of the membranes while the cold feed solution from the absorber flowed away from the shell side. Heat transfer and mass transfer occurred simultaneously in the membrane module, and only water vapor could diffuse across the membrane pore due to the water vapor pressure difference between the inside and outside of the membrane. Mathematical equations of the heat and mass transfer processes in the membrane heat exchanger were built, and the parallel flow process and the counter flow process were compared by numerical simulation. The simulation results show that the counter flow process was the better flow mode because the mean temperature difference was larger and the mass transfer was more steadily from the lumen side to the shell side. The heat caused by water vapor mass transfer may account for one-third of the total heat transfer. As a result, the membrane heat exchanger not only reinforced the heat recovery but also enlarged the deflation range and reduced the circulation rate and the heat loads of the generator and absorber. Eventually, the coefficient of performance of the heat exchanger was increased.

Role of Preoperative Albumin Quotient in Surgical Planning for Posttraumatic Syringomyelia: A Comparative Cohort Study

Pingchuan Xia,Houyuan Lv,Chenghua Yuan,Wanru Duan,Jiachen Wang,Jian Guan,Yueqi Du,Can Zhang,Zhenlei Liu,Kai Wang,Zuowei Wang,Xingwen Wang,Hao Wu,Zan Chen,Fengzeng Jian 대한척추신경외과학회 2024 Neurospine Vol.21 No.1

Objective: Surgical procedures for patients with posttraumatic syringomyelia (PTS) remain controversial. Until now, there have been no effective quantitative evaluation methods to assist in selecting appropriate surgical plans before surgery. Methods: We consecutively enrolled PTS patients (arachnoid lysis group, n = 42; shunting group, n = 14) from 2003 to 2023. Additionally, 19 intrathecal anesthesia patients were included in the control group. All patients with PTS underwent physical and neurological examinations and spinal magnetic resonance imaging preoperatively, 3–12 months postoperatively and during the last follow-up. Preoperative lumbar puncture was performed and blood-spinal cord barrier disruption was detected by quotient of albumin (Qalb, cerebrospinal fluid/serum). Results: The ages (p = 0.324) and sex (p = 0.065) of the PTS and control groups did not differ significantly. There were also no significant differences in age (p = 0.216), routine blood data and prognosis (p = 0.399) between the arachnoid lysis and shunting groups. But the QAlb level of PTS patients was significantly higher than that of the control group (p < 0.001), and the shunting group had a significantly higher QAlb (p < 0.001) than the arachnoid lysis group. A high preoperative QAlb (odds ratio, 1.091; 95% confidence interval, 1.004–1.187; p = 0.041) was identified as the predictive factor for the shunting procedure, with the receiver operating characteristic curve showing 100% specificity and 80.95% sensitivity for patients with a QAlb > 12.67. Conclusion: Preoperative QAlb is a significant predictive factor for the types of surgery. For PTS patients with a QAlb > 12.67, shunting represents the final recourse, necessitating the exploration and development of novel treatments for these patients.

Channel Characteristics of Indoor Wireless Infrared Communication System Due to Different Transceiver Conditions

Chuan Peng,Zan Wang,Ji Do Kim,Jae Kyung Pan 한국통신학회 2007 한국통신학회 학술대회논문집 Vol.2007 No.11

Transmission Characteristics of Indoor Infrared Diffuse Links Employing Three-Beam Optical Transmitters and Non-Imaging Receivers

왕잔,반재경,Wang, Zan,Pan, Jae-Kyung The Korea Institute of Information and Commucation 2008 韓國通信學會論文誌 Vol.33 No.12A

Diffuse wireless optical communication offers more robust optical links in terms of coverage and shadowing than line-of-sight links. However, traditional diffuse wireless infrared (IR) transceiver systems are more susceptible to multi-path distortion and great power decrease, which results in limiting high-speed performance. Multi-beam is an effective technique to compensate for multi-path distortion in a wireless infrared environment. The goal of this paper is to analyze the transmission characteristics by replacing traditional diffuse system (TDS) which contains single wide angle transmitter and single element receiver by system consisting of three-beam transmitter and non-imaging receiver (TNS) attached with compound parabolic concentrator (CPC). In the simulation, we use the recursive model developed by Barry and Kahn and build the scenario based on 10 different cases which have been listed in Table 1. Moreover, we also check the reliability of the TNS diffuse link channel by BER test on the basis of different receiver positions and room sizes. The simulation results not only show the basic transmission characteristics of TNS diffuse link, but also are references to design more efficient and reliable indoor infrared transmission systems.

Three homologous genes encoding functional D8-sphingolipid desaturase in Populus tomentosa

Shu-Fen Li,Zan-Min Hu,Guo-Jun Zhang,Ying-Chun Yuan,Cong-Hui Wang,Wu-Jun Gao,Chuan-Liang Deng,Long-Dou Lu 한국유전학회 2014 Genes & Genomics Vol.36 No.3

Δ8-sphingolipid desaturase is characterized by itsability to catalyze desaturation at the C8 position of the longchainbase of sphingolipids in plants. No previous studieshave been conducted on genes encoding Δ8-sphingolipiddesaturases in the woody plant Populus tomentosa. In thisstudy, three genes that encode Δ8-sphingolipid desaturasewere isolated fromP. tomentosa. Among these genes, PtD8Aand PtD8B showed high sequence similarity; whereas PtD8Cexhibited large sequence divergence.RT-PCRresults showedthat PtD8A and PtD8B were expressed in all tissues detected,whereas PtD8C was not expressed in roots. Heterologousexpression in yeast revealed that PtD8A/B/C were functionalΔ8-sphingolipid desaturases, and can catalyze the C18-phytosphingeninedesaturation to produce 8(Z)- and 8(E)-C18-phytosphingenine.However, the conversion rate and ratios ofthe two products differed. Compared with control cells,transgenic yeasts expressing PtD8A/B/C exhibited enhancedaluminum tolerance. Our findings further elucidated thebiochemical functions and evolutionary history ofΔ8-sphingolipid desaturases in plants. Candidate genes forbreeding new poplar germplasm resources with enhancedtolerance ability to aluminium were also provided.

Channel Characteristics of Indoor Wireless Infrared Communication System Due to Different Transceiver Conditions

Chuan Peng(팽천),Zan Wang(왕잔),Ji Do Kim(김지도),Jae Kyung Pan(반재경) 한국통신학회 2008 韓國通信學會論文誌 Vol.33 No.2A

In this paper, we consider the diffuse type of indoor wireless optical communication (WOC) system. To find the channel characteristics of indoor wireless infrared communication system, we investigate the simulation process to get the impulse response of diffuse type and analyze the scenario of the indoor structure which we have built. The simulation results of the impulse response include power ratio and time delay due to bounce times. We get and discuss the receiving power distribution according to six configurations which have different transmitter and receiver positions and reflection coefficients of the indoor structure assumed. The results of this paper are useful to design the indoor wireless optical communication systems.

Insulin Inhibits the Expression of Adiponectin and AdipoR2 mRNA in Cultured Bovine Adipocytes

Sun, Y.G.,Zan, L.S.,Wang, H.B.,Guo, H.F.,Yang, D.P.,Zhao, X.L.,Gui, L.S. Asian Australasian Association of Animal Productio 2009 Animal Bioscience Vol.22 No.10

Adiponectin is an adipocyte-derived protein that has a regulatory role in energy homeostasis and influences insulin sensitivity. Its effects on glucose utilization and lipid metabolism are mediated by AdipoR1 and AdipoR2. How insulin affects adiponectin gene expression and secretion is still controversial. This study was conducted to determine the expression of adiponectin, AdipRs and $PPAR-\gamma$ during the differentiation of bovine preadipocytes and the effect of insulin on expression of these genes in bovine adipocytes. The bovine preadipocytes started to accumulate lipids three days after differentiation was induced, with increased expression of adiponectin, AdipoR2 and $PPAR-\gamma$ mRNAs. Insulin decreased the expression of adiponectin mRNA in a dose- and time-dependent fashion, and the inhibition was detectable at insulin concentrations as low as 10 nM and as early as 2 h after addition of 100 nM insulin. Insulin also inhibited the expression of AdipoR2 mRNA at concentrations from 1 to 1,000 nM or 24 h after addition of 100 nM insulin, but did not affect the expression of AdipoR1 in bovine adipocytes. Inhibition of PI3K with LY294002 reversed the inhibition of adiponectin and AdipoR2 mRNA expression by insulin. These results suggest that insulin suppresses the expression of adiponectin and AdipoR2 at least partially via the PI3K signal pathway.