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Study of PD Location in Generators by PD Pulses Propagation
Cheng, Yang-Chun,Li, Cheng-Rong,Wang, Wei The Korean Institute of Electrical and Electronic 2006 Transactions on Electrical and Electronic Material Vol.7 No.5
When a partial discharge takes place at the stator of a generator, the electrical pulse will propagate along the stator bars and the capacitor chains formed by the end part of the stator winds. On the first path, the pulse propagates as a travel wave at slow speed. On the second path, the pulse propagates at quick speed. Based on the data of the experiments on a real 50 MW steam generator, the author has found the pulses can propagate by magnetic field of the stator winding. It was studied that how to locating the partial discharge by signals coming from the different paths, including the features of signals on the two paths at time domain and frequency domain, the measurement frequency rang of the signals, the blind area, the advantage and disadvantage of this method.
Ruptured Spinal Dermoid Cysts with Lipid Droplets into the Syrinx Cavity : Reports of Fourteen Cases
Cheng, Cheng,Li, Rong,Gao, Haihao,Tao, Benzhang,Wang, Hui,Sun, Mengchun,Gao, Gan,Wang, Jianzhen,Shang, Aijia The Korean Neurosurgical Society 2022 Journal of Korean neurosurgical society Vol.65 No.3
Objective : Dermoid cysts are uncommon in spinal cord tumors, and the phenomenon of their spontaneous rupture into the syrinx cavity is quite rare. We aimed to analyze the imaging characteristics and etiologies, and propose some surgical strategies, for this uncommon phenomenon. Methods : We retrospectively reviewed 14 cases with spinal dermoid cysts that ruptured into the cervical and thoracic syrinx cavity. There were six male and eight female cases, aged 21 to 46 years, who had lipid droplets in the syrinx cavity from C1 to L3. The dermoid cysts were always located at the conus. Based on patients' complaints, clinical manifestations, and imaging results, we adopted tumor excision and/or syrinx cavity aspiration in one stage or multiple stages. Results : Three patients had only a syrinx cavity aspiration surgery due to a history of dermoid cyst excision. Eight patients had dermoid cyst resection and syrinx cavity aspiration in one stage. One patient was operated upon in two stages due to the development of new symptoms at nine months follow-up. Two patients underwent only tumor resection since they did not show similar symptoms or signs caused by the cervicothoracic syrinx. The axial magnetic resonance imaging indicated that the lipid droplets were always not at the center but were eccentric. The clinical effect was satisfactory during the follow-up period in this group. Conclusion : The lipid droplets filled the spinal syrinx cavity, not entirely confined to the central canal. Based on the chief complaints and associated signs, we adopted different surgical strategies and had satisfactory clinical results.
Nonlinear Error Compensation of Complex Surface for Five-axis Machining
Cheng De-rong,Deng Shi-ping,Xing Xiao-Lin 보안공학연구지원센터 2015 International Journal of Hybrid Information Techno Vol.8 No.12
In order to solve non-linear errors caused by rotational movement of the rotary axis, firstly, it analyzes how non-linear errors are generated in the five-axis machining, and establishes the non-linear error model of complex surface in 3D space. Then it proposes a method of controlling and compensating for nonlinearity errors by introducing the interpolate point based on smoothing tool axis vector. In the method of surface interpolation, it is suggested to add an interpolation point, keep the tool axis vector on sector surface boundary within the start and end tool axis vector of the program block, and maintain the tool axis vector velocity and acceleration continuity. Simulation results show the nonlinearity errors of the fan blade machining are effectively controlled.
Automatic Image Segmentation with PCNN Algorithm Based on Grayscale Correlation
Hai-Rong Ma,Xin-Wen Cheng 보안공학연구지원센터 2014 International Journal of Signal Processing, Image Vol.7 No.5
In order to use pulse coupled neural networks (PCNN) for precise automatic image segmentation, we propose an improved PCNN model. We first establish a connection weight matrix based on the image local gray correlation and on the Euclid distance. We then used the minimum variance ratio criterion to automatically determine PCNN cycle times, and achieve automatic image segmentation. The simulation results show that this method can automatically determine the number of iterations PCNN, and that it is highly feasible and better segmentation effect.
Feng Xu,Hua Cheng,Rong Cai,Lin Ling Li,Jie Chang,Jun Zhu,Feng Xia Zhang,Liu Ji Chen,Yan Wang,Shu Han Cheng,Shui Yuan Cheng 한국분자세포생물학회 2008 Molecules and cells Vol.26 No.6
Anthocyanidin synthase (ANS, leucoanthocyanidin oxygenase), a 2-oxoglutarate iron-dependent oxygenase, catalyzed the penultimate step in the biosynthesis of the anthocyanin class of flavonoids, from the colorless leucoanthocyanidins to the colored anthocyanidins. The full-length cDNA and genomic DNA sequences of ANS gene (designated as GbANS) were isolated from Ginkgo biloba for the first time. The full-length cDNA of GbANS contained a 1062-bp open reading frame (ORF) encoding a 354-amino-acid protein. The genomic DNA analysis showed that GbANS gene had three exons and two introns. The deduced GbANS protein showed high identities to other plant ANSs. The conserved amino acids (H-X-D) ligating ferrous iron and residues (R-X-S) participating in 2-oxoglutarate binding were found in GbANS at the similar positions like other ANSs. Southern blot analysis indicated that GbANS belonged to a multi-gene family. The expression analysis by real-time PCR showed that GbANS expressed in a tissue-specific manner in G. biloba. GbANS was also found to be up-regulated by all of the six tested abiotic stresses, UV-B, abscisic acid, sucrose, salicylic acid, cold and ethylene, consistent with the promoter region analysis of GbANS. The recombinant protein was successfully expressed in E. coli strain with pET-28a vector. The in vitro enzyme activity assay by HPLC indicated that recombinant GbANS protein could catalyze the formation the cyanidin from leucocyanidin and conversion of dihydroquercetin to quercetin, suggesting GbANS is a bifunctional enzyme within the anthocyanidin and flavonol biosynthetic pathway.
Refined numerical simulation in wind resource assessment
Cheng, Xue-Ling,Li, Jun,Hu, Fei,Xu, Jingjing,Zhu, Rong Techno-Press 2015 Wind and Structures, An International Journal (WAS Vol.20 No.1
A coupled model system for Wind Resource Assessment (WRA) was studied. Using a mesoscale meteorological model, the Weather Research and Forecasting (WRF) model, global-scale data were downscaled to the inner nested grid scale (typically a few kilometers), and then through the coupling Computational Fluid Dynamics (CFD) mode, FLUENT. High-resolution results (50 m in the horizontal direction; 10 m in the vertical direction below 150 m) of the wind speed distribution data and ultimately refined wind farm information, were obtained. The refined WRF/FLUENT system was then applied to assess the wind resource over complex terrain in the northern Poyang Lake region. The results showed that the approach is viable for the assessment of wind energy.
Structure and bioactivity of triterpenoids from the stems of Schisandra sphenanthera
Cheng-Qin Liang,Rong-Hua Luo,Ju-Ming Yan,Yan Li,Xiao-Nian Li,Yi-Ming Shi,Shan-Zhai Shang,Zhong-Hua Gao,Liu-Meng Yang,Yong-Tang Zheng,Wei-Lie Xiao,Hong-Bin Zhang,Han Dong Sun 대한약학회 2014 Archives of Pharmacal Research Vol.37 No.2
Two new triterpenoids, schisphendilactoneA and B (1 and 2), together with three known triterpenoids,were isolated from the stems of Schisandra sphenanthera. Their structures were elucidated by spectroscopic methods,and the absolute configuration of 1 was determined bysingle-crystal X-ray diffraction. Compound 2 showedmoderate inhibitory activity against SW480 cancer cellline, and compound 5 exhibited promising anti-HIV-1activity with EC50 value of 0.52 lg ml-1 and therapeuticindex value of 117.12.
Flexible tactile sensor array for foot pressure mapping system in a biped robot
Cheng-Hsin Chuang,Yi-Rong Liou,Ming-Yuan Shieh 국제구조공학회 2012 Smart Structures and Systems, An International Jou Vol.9 No.6
Controlling the balance of motion in a context involving a biped robot navigating a rugged surface or a step is a difficult task. In the present study, a 3×5 flexible piezoelectric tactile sensor array is developed to provide a foot pressure map and zero moment point for a biped robot. We introduce an innovative concept involving structural electrodes on a piezoelectric film in order to improve the sensitivity. The tactile sensor consists of a polymer piezoelectric film, PVDF, between two patterned flexible print circuit substrates (FPC). Additionally, a silicon rubber bump-like structure is attached to the FPC and covered by a polydimethylsiloxane (PDMS) layer. Experimental results show that the output signal of the sensor exhibits a linear behavior within 0.2 N ~ 9 N, while its sensitivity is approximately 42 mV/N. According to the characteristic of the tactile sensor, the readout module is designed for an in-situ display of the pressure magnitudes and distribution within 3×5 taxels. Furthermore, the trajectory of the zero moment point (ZMP) can also be calculated by this program. Consequently, our tactile sensor module can provide the pressure map and ZMP information to the in-situ feedback to control the balance of moment for a biped robot.
Cheng Gui,Yike Zhang,Rui Jin,Yang Song,Rong Li,Yanjun Xing 한국섬유공학회 2021 Fibers and polymers Vol.22 No.4
Most previous work on the preparation of electrode materials has usually used to grind carbon nanofibers and addnon-reactive binders, which lead to limited surface area and lower electrochemical performance in electrode materials. In thisstudy, porous carbon nanofibers were prepared from non-miscible PAN/PVDF polymer blends by electrospinning andcarbonization to obtain electrode materials with high performance and high specific surface area. In the process of preparingelectrode materials, carbon nanofibers can be directly prepared as electrodes with high-performance and flexibility withoutadding any inactive materials, such as polymer binders or electronic conductors. Results showed that PF-C-50 has themaximum specific surface area of 773 m2 g-1 and the specific capacitance as high as 181 F/g at the current density of 0.4 A/gand 134 F/g at the current density of 1 A/g. PF-C-80 exhibits a specific capacitance as high as 156 F/g at the current densityof 0.4 A/g and 117 F/g at the current density of 1 A/g with the smallest IR drop and Rct. The prepared porous carbonnanofiber electrode improves the electrochemical performance and flexibility of the electrode material. These uniquestructures and characteristic materials can be excellent candidates for high-performance flexible electrodes, laying a goodfoundation for wearable devices.