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Numerical Study of Ion Orbits in EAST Plasmas with a Current-reversal Equilibrium Configuration
Yi-jun Zhong,Xue-yu Gong,Ye-ming Hu,Xin-xia Li 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.66 No.11
By solving the Grad-Shafranov equation in the cylindrical coordinate system, we numerically obtain the tokamak plasma equilibrium configurations of the conventional mode and the high-to-lowfield- side current-reversal equilibrium mode (HL-CREC) by using the discharge parameters for the Experimental Advanced Superconductor Tokamak (EAST). By coupling with the particle’s motion equation, we obtain the orbits of trapped particles and passing particles under both equilibrium configurations. We find that the orbit of the passing particle in the HL-CREC is wholly confined on the low-field side and that the half width of the banana orbit of trapped particles increases greatly compared with those in the conventional equilibrium configuration. In addition, the ion loss is studied based on the Monte Carlo method. The results show that for ions near the plasma edge, a much high ion loss rate can be obtained in HL-CREC than that in the conventional equilibrium configuration.
Zhong-Yi Cai,Lin-Lin Li,Mi Wang,Ming-Zhe Li 한국정밀공학회 2014 International Journal of Precision Engineering and Vol. No.
Continuous roll forming (CRF) is a process to form three-dimensional surface based on the rolling deformation of sheet metal. Unliketraditional rolling process where the working rolls are straight and rigid, two small-diameter bendable forming rolls are used herein,and the sheet metal is bent in longitudinal and transverse directions simultaneously after it is compressed between a pair of bendedrolls. The formed surface is controlled by the curved shapes of the forming rolls and the gap between the two rolls, and the roll gapis the crucial parameter of CRF process. In this paper, the required velocity distribution of material across the exit of roll gap forthe formation of a smooth surface is analyzed, the formulations for the CRF process design is derived and a method to predict thelongitudinal bending deformation generated by roll gap is presented. Finally, the validity of the presented methods and theoreticalmodels are demonstrated by numerical simulations and CRF tests for typical surface parts.
Continuous Sheet Metal Forming for Doubly Curved Surface Parts
Zhong-Yi Cai,Ying-Wu Lan,Ming-Zhe Li,Zhi-Qing Hu,Mi Wang 한국정밀공학회 2012 International Journal of Precision Engineering and Vol. No.
Continuous sheet metal forming (CSMF) is a novel technology for manufacturing doubly curved sheet metal parts. In this process,an upper flexible roll and two lower flexible rolls are employed as a forming tool, with the rotation of flexible rolls, the sheet metal is bent in the longitudinal and transverse directions simultaneously. In this study, the basic principle of CSMF system is introduced and the basic mathematical model to control the CSMF process is presented. Based on the analysis of the sheet metal deformation in longitudinal direction, the formulations to determine the finial curvature of the deformed sheet metal and to estimate the downward displacement of upper roll are obtained. Forming experiments for torus-shaped surface and saddle-shaped surface were carried out. The dimensional accuracy and smoothness of the CSMF parts were measured and analyzed. The experiment results confirm the validity of the presented mathematical models and shows that CSMF can be effectively used in forming of doubly curved surface parts.
Yi-Cun Zhong,Ting Zhang,Wen Di,Wei-Ping Li 대한부인종양학회 2013 Journal of Gynecologic Oncology Vol.24 No.3
Objective: Over-expression of thrombin in ovarian cancer cells is associated with poor prognosis. In this study, we investigated the role of thrombin in inducing epithelial-mesenchymal transition (EMT) in SKOV3 epithelial ovarian cancer cells. Methods: After thrombin treatment SKOV3 cells were subjected to western blots, reverse-transcription PCR, and enzyme-linked immunosorbent assay to quantify EMT-related proteins, mRNA expression of SMAD2, DKK1, and sFRP1, and the secretion of matrix metalloproteinases (MMPs) and cytokines. Meanwhile, invasion ability was evaluated using transwell assays. Results: The results indicated a dose- and time-dependent down-regulation of E-cadherin and upregulation of N-cadherin and vimentin in thrombin-treated SKOV3 cells, compared with the thrombin-free control group (p<0.05). There was a dose-and time-dependent increase in the levels of SMAD2 and DKK1 mRNAs and a decrease in the levels of sFRP1 mRNA in thrombin-treated SKOV3 cells compared to control cells (p<0.05). Thrombin-treated SKOV3 cells exhibited increased secretion of MMP-9, MMP-2, interleukin (IL)-8, and IL-6 and increased invasion compared to untreated cells (p<0.05). Thrombin altered the morphology of SKOV3 cells to a spindle-like phenotype. Addition of hirudin to thrombin-treated cells reversed the effects of thrombin. Conclusion: Thrombin induced EMT and promoted the invasion of SKOV3 cells, possibly via distinct signaling pathways. Hirudin inhibited the effects of thrombin, suggesting that anticoagulant therapy could be a novel therapeutic strategy for ovarian carcinoma.
No Blind Spot: Network Coverage Enhancement Through Joint Cooperation and Frequency Reuse
Zhong, Yi,Qiao, Pengcheng,Zhang, Wenyi,Zheng, Fu-chun The Korea Institute of Information and Commucation 2016 Journal of communications and networks Vol.18 No.5
Both coordinated multi-point transmission and frequency reuse are effective approaches to mitigate inter-cell interference and improve network coverage. The motivation of this work is to explore the manner to effectively utilize the spectrum resource by reasonably combining cooperation and frequency reuse. The $Mat{\acute{e}}rn$ cluster process, which is appropriate to model networks with hot spots, is used to model the spatial distribution of base stations. Two cooperative mechanisms, coherent and non-coherent joint transmission (JT), are analyzed and compared. We also evaluate the effect of multiple antennas and imperfect channel state information. The simulation reveals that the proposed approach to combine cooperation and frequency reuse is effective to improve the network coverage for users located at both the center and the boundary of the cooperative region.
Zhong-Yi Chu,Shao-Bo Yan,Jian Hu,Shan Lu 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.2
Underactuated gripper has a broad application in the field of space robot and industrial robot because of its better shape-adaptation. However, because of the underactuated characteristics, it is a great challenge to accurately obtain the displacement of the contact point between the finger and grasped object, which makes it difficult to control the gripper grasp stably, especially the environmental parameters are unknown. This paper develops the identification of the unknown environmental parameters using a tactile array sensor based on the recursive leastsquares (RLS) method. The unknown environments are described as linear systems with unknown dynamics, and the environmental parameters are identified using the measured contact force and the derived displacement of the contact point which is obtained through the underactuated gripper dynamics. Meanwhile, an impedance adaptive control is presented to match the variability of the environment parameters, and the desired impedance model is imposed to the underactuated gripper to achieve stable grasp. A cost function that measures the contact force, velocity and displacement error is defined, and the critical impedance parameters are found to minimize it. At last, a co-simulation of ADAMS and MATLAB for an underactuated gripper grasp is implemented to show the feasibility of environmental parameters identification and its adaptive method.
Study on the constitutive behavior and hot deformation characteristic of Mg-4Sm-2Zn-0.5Zr alloy
Zhong-Yi Cai,Chao-jie Che,Ruo-Han Chang,Li-Ren Cheng,Qing-Min Chen 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.3
Mg–4Sm–2Zn–0.5Zr alloy is a new type of heat-resistant magnesium alloy, it has the mechanical properties similar to EZ33 alloy but is much cheaper than EZ33 in cost since Samarium (Sm) rather than Nd was employed in the alloy. In this paper, based on isothermal compression tests in the temperature range of 350–450 °C and strain rate range of 0.001–1.0 s−1, the Arrhenius-type constitutive equations for this alloy were established, and the hot working flow behavior and the microstructures of the alloy were examined. To evaluate the hot deformation mechanisms and determine the optimal processing parameters, 3D processing maps under different deformation conditions were developed according to the dynamic material model and Muthy instability criterion. The hot extrusion experiments were carried out, and the results show the predictions of processing maps are in agreement with the experimental results.
Study on Aging Characteristics and Chemical Composition of Hydrogenated Transformer Oil
Yi-Hua Qian,Yi-Bin Huang,Qiang Fu,Zhen-Sheng Zhong 대한전기학회 2013 Journal of Electrical Engineering & Technology Vol.8 No.3
Under the condition of Baader aging, the chemical composition variation and the influence of transformer oil aging on electrical properties such as dielectric loss factor and physicchemical properties such as interfacial tension were studied in the aging precess. Moreover, the correlation between hydrogenated transformer oil electrical and physic-chemical properties and its chemical composition variation were also investigated. The results show that these parameters of physic-chemical and electrical properties of hydrogenated transformer oil relate to each other and have closed correlation with chemical composition.