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Declutching control of a point absorber with direct linear electric PTO systems
Zhang, Xian-Tao,Yang, Jian-Min,Xiao, Long-Fei Techno-Press 2014 Ocean systems engineering Vol.4 No.1
Declutching control is applied to a hemispherical wave energy converter with direct linear electric Power-Take-Off systems oscillating in heave direction in both regular and irregular waves. The direct linear Power-Take-Off system can be simplified as a mechanical spring and damper system. Time domain model is applied to dynamics of the hemispherical wave energy converter in both regular and irregular waves. And state space model is used to replace the convolution term in time domain equation of the heave oscillation of the converter due to its inconvenience in analyzing the controlled motion of the converters. The declutching control strategy is conducted by optimal command theory based on Pontryagin's maximum principle to gain the controlled optimum sequence of Power-Take-Off forces. The results show that the wave energy converter with declutching control captures more energy than that without control and the former's amplitude and velocity is relatively larger. However, the amplification ratio of the absorbed power by declutching control is only slightly larger than 1. This may indicate that declutching control method may be inapplicable for oscillating wave energy converters with direct linear Power-Take-Off systems in real random sea state, considering the error of prediction of the wave excitation force.
Zhang Qing,He Yi-Jing,Zhu Yu-Hang,Dai Min-Chen,Pan Man-Man,Wu Jia-Qi,Zhang Xian,Gu Ying-Er,Wang Fang-Fang,Xu Xiang-Rong,Qu Fan 한국한의학연구원 2020 Integrative Medicine Research Vol.9 No.3
Background: During the COVID-19 epidemic period, Traditional Chinese Medicine (TCM) course for international students of Medical Bachelor, Bachelor of Surgery (MBBS) program in Zhejiang University has shifted from traditional classroom to online environment. This study aimed to investigate MBBS international students’ perception on online TCM course, and to assess the online learning efficacy. Methods: A total of 84 MBBS international students attending course of “Basic Traditional Chinese Medicine” during 2020 academic years at Zhejiang University were enrolled in this study. A quantitative questionnaire was respectively completed before and after the TCM course using a pretest–post-test design. By means of two online learning platforms, Learning in ZJU and DingTalk, TCM course was broadcast in both live and archived format to students. Results: A total of 48 participants completed both baseline and follow-up questionnaires. The majority of participants preferred face-to-face classroom learning (26, 54.17% of total) when compared with online learning. Students felt that the course had brought in much benefits (mean 3.88, SD 0.87), and they were satisfied with the course content (mean 3.83, SD 0.95). Students’ TCM related knowledge and their behaviors of discussion and consulting were significantly improved by online TCM course (all P < 0.001). Students’ awareness of the necessity of TCM education and their feeling of difficulty in learning TCM were significantly strengthened (P = 0.042, 0.025, respectively). Conclusion: Online learning is a good alternative for TCM course of MBBS international students when classroom learning is suspended, whereas it cannot replace the need for onsite and face-to-face learning.
Mu, Xian-Min,Shi, Wei,Sun, Li-Xin,Li, Han,Wang, Yu-Rong,Jiang, Zhen-Zhou,Zhang, Lu-Yong Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.4
Background/Aim: Pristimerin isolated from Celastrus and Maytenus spp can inhibit proteasome activity. However, whether pristimerin can modulate cancer metastasis is unknown. Methods: The impacts of pristimerin on the purified and intracellular chymotrypsin proteasomal activity, the levels of regulator of G protein signaling 4 (RGS 4) expression and breast cancer cell lamellipodia formation, and the migration and invasion were determined by enzymatic, Western blot, immunofluorescent, and transwell assays, respectively. Results: We found that pristimerin inhibited human chymotrypsin proteasomal activity in MDA-MB-231 cells in a dose-dependent manner. Pristimerin also inhibited breast cancer cell lamellipodia formation, migration, and invasion in vitro by up-regulating RGS4 expression. Thus, knockdown of RGS4 attenuated pristimerin-mediated inhibition of breast cancer cell migration and invasion. Furthermore, pristimerin inhibited growth and invasion of implanted breast tumors in mice. Conclusion: Pristmerin inhibits proteasomal activity and increases the levels of RGS4, inhibiting the migration and invasion of breast cancer cells.
Shun-Qi Zhang,Min Chen,Guo-Zhong Zhao,Zhan-Xi Wang,Rüdiger Schmidt,Xian-Sheng Qin 국제구조공학회 2017 Smart Structures and Systems, An International Jou Vol.19 No.6
The complexity of macro-fiber composite (MFC) materials increasing the difficulty in simulation and analysis of MFC integrated structures. To give an accurate prediction of MFC bonded smart structures for the simulation of shape and vibration control, the paper develops a linear electro-mechanically coupled static and dynamic finite element (FE) models based on the first-order shear deformation (FOSD) hypothesis. Two different types of MFCs are modeled and analyzed, namely MFC-d31 and MFC-d33, in which the former one is dominated by the d31 effect, while the latter one by the d33 effect. The present model is first applied to an MFC-d33 bonded composite plate, and then is used to analyze both active shape and vibration control for MFC-d31/-d33 bonded plate with various piezoelectric fiber orientations.
Temporal coherent image segmentation and its applications
Song-Hai Zhang,Xian-Ying Li,Tao Chen,Yi-Fei Zhang,Shi-Min Hu,Ralph Martin (사)한국CDE학회 2010 한국CAD/CAM학회 국제학술발표 논문집 Vol.2010 No.8
We propose a trapped-ball method for image segmentation, which is fast, supports non-uniformly colored regions, and allows robust region segmentation even in the presence of imperfectly linked region edges. We also introduce two applications by using the trapped-ball image segmentation, for temporal coherent animations generation and editing. First, we present a system for vectorizing 2D raster format cartoon animations by the segmentation method and background construction. The output animations are visually flicker free, smaller in file size, and easy to edit. And then we present an automatic method for online video stream stylization, producing a temporally coherent output video stream, based on the trapped-ball segmentation and optical flow. Our system transforms video into an abstract style with large regions of constant color and highlighted bold edges.
Study on Economized Vapor Injection Heat Pump System Using Refrigerant R32
Yaoguang Shi,XIAN-MIN GUO,Xinyu Zhang 대한설비공학회 2016 International Journal of Air-Conditioning and Refr Vol.24 No.1
The refrigerant R32 is considered as a potential alternative refrigerant of R410A because of its low global warming potential (GWP) and the basic thermodynamic parameters. It can e®ectively improve the heating e±ciency and reduce the discharge temperature of the compressor to use the economized vapor injection (EVI) refrigeration system. In this paper, the performance of the EVI heat pump system using refrigerant R32 is investigated experimentally under the conditions of the evaporating temperature ranged from 2C to 15C. The experimental results indicate that the injection ratio, heat capacity and power consumption of the EVI heat pump system increase with the injection pressure. The maximum injection ratio of the EVI heat pump system is about 33% under the evaporating temperature of 15C. For the EVI heat pump system, the system COP achieves the maximum value as the injection pressure ranges from 1.48 MPa to 1.54 MPa when the evaporating temperature is lower than 6C. The discharge temperature of the EVI heat pump system drops by 11C under the evaporating temperature of 15C. As the evaporating temperature is below 6C, the COP of the EVI heat pump system is higher than that of the traditional single stage heat pump.