Response of plasma rotation to resonant magnetic perturbations in J-TEXT tokamak

Yan, W,Chen, Z Y,Huang, D W,Hu, Q M,Shi, Y J,Ding, Y H,Cheng, Z F,Yang, Z J,Pan, X M,Lee, S G,Tong, R H,Wei, Y N,Dong, Y B IOP 2018 Plasma physics and controlled fusion Vol.60 No.3

<P>The response of plasma toroidal rotation to the external resonant magnetic perturbations (RMP) has been investigated in Joint Texas Experimental Tokamak (J-TEXT) ohmic heating plasmas. For the J-TEXT’s plasmas without the application of RMP, the core toroidal rotation is in the counter-current direction while the edge rotation is near zero or slightly in the co-current direction. Both static RMP experiments and rotating RMP experiments have been applied to investigate the plasma toroidal rotation. The core toroidal rotation decreases to lower level with static RMP. At the same time, the edge rotation can spin to more than 20 km s<SUP>−1</SUP> in co-current direction. On the other hand, the core plasma rotation can be slowed down or be accelerated with the rotating RMP. When the rotating RMP frequency is higher than mode frequency, the plasma rotation can be accelerated to the rotating RMP frequency. The plasma confinement is improved with high frequency rotating RMP. The plasma rotation is decelerated to the rotating RMP frequency when the rotating RMP frequency is lower than the mode frequency. The plasma confinement also degrades with low frequency rotating RMP.</P>

CHINA'S RELATIONS WITH THE TWO SUPERPOWERS IN THE CONTEXT OF MODERNIZATION DIPLOMACY

Cheng, Joseph Y S 경남대학교 극동문제연구소 1988 ASIAN PERSPECTIVE Vol.12 No.2

Magnetization Reversal Behaviors and Domain Wall Magnetoresistance Effect in Nanobridges

Y. S. Chen,Jen-Hwa Hsu,C. Yu,K. W. Cheng,S. F. Lee,Y. Liou,Y. D.Yao 한국자기학회 2008 한국자기학회 학술연구발표회 논문개요집 Vol.- No.-

CHINA'S RELATIONS WITH THE TWO SUPERPOWERS IN THE CONTEXT OF MODERNIZATION DIPLOMACY

Cheng, Joseph Y.S. The Institute for Far Eastern Studies Kyungnam Uni 1988 ASIAN PERSPECTIVE Vol.12 No.2

Formation kinetics and structures of high-density vertical Si nanowires on (111)Si substrates

S. L. Cheng,C. H. Chung,Y. H. Chang 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.3

We report here the first study of formation kinetics of high-density vertical Si nanowire arrays formed on (111)Si substrates in aqueous AgNO3/HF etching solutions. From TEM and electron diffraction analyses, the as-prepared Si nanowires were determined to be perfectly single crystals and the axial orientation of the Si nanowires was identified to be parallel to the [111] direction, which was identical to the orientation of the (111)Si wafers used. The typical widths of the Si nanowires prepared are in the range of 25-150 nm. The lengths of the Si nanowires were found to increase linearly with the reaction time in samples treated at 5-30℃. By measuring the growth rate at different temperatures, the activation energy for the linear formation of Si nanowire arrays on blank-(111)Si was obtained from an Arrhenius plot to be about 0.38 eV. The results of the contact angle measurements further indicated that the hydrophobicity of the Si samples was enhanced significantly by the formation of Si nanowire arrays. The hydrophobic behavior of the HF-treated Si nanowire arrays could be explained by Cassie’s model. We report here the first study of formation kinetics of high-density vertical Si nanowire arrays formed on (111)Si substrates in aqueous AgNO3/HF etching solutions. From TEM and electron diffraction analyses, the as-prepared Si nanowires were determined to be perfectly single crystals and the axial orientation of the Si nanowires was identified to be parallel to the [111] direction, which was identical to the orientation of the (111)Si wafers used. The typical widths of the Si nanowires prepared are in the range of 25-150 nm. The lengths of the Si nanowires were found to increase linearly with the reaction time in samples treated at 5-30℃. By measuring the growth rate at different temperatures, the activation energy for the linear formation of Si nanowire arrays on blank-(111)Si was obtained from an Arrhenius plot to be about 0.38 eV. The results of the contact angle measurements further indicated that the hydrophobicity of the Si samples was enhanced significantly by the formation of Si nanowire arrays. The hydrophobic behavior of the HF-treated Si nanowire arrays could be explained by Cassie’s model.

Semi-active control of ship mast vibrations using magneto-rheological dampers

Cheng, Y.S.,Au, F.T.K.,Zhong, J.P. Techno-Press 2008 Structural Engineering and Mechanics, An Int'l Jou Vol.30 No.6

On marine vessels, delicate instruments such as navigation radars are normally mounted on ship masts. However the vibrations at the top of mast where the radar is mounted often cause serious deterioration in radar-tracking resolution. The most serious problem is caused by the rotational vibrations at the top of mast that may be due to wind loading, inertial loading from ship rolling and base excitations induced by the running propeller. This paper presents a method of semi-active vibration control using magneto-rheological (MR) dampers to reduce the rotational vibration of the mast. In the study, the classical optimal control algorithm, the independent modal space control algorithm and the double input - single output fuzzy control algorithm are employed for the vibration control. As the phenomenological model of an MR damper is highly nonlinear, which is difficult to analyse, a back- propagation neural network is trained to emulate the inverse dynamic characteristics of the MR damper in the analysis. The trained neural network gives the required voltage for each MR damper based on the displacement, velocity and control force of the MR damper quickly. Numerical simulations show that the proposed control methods can effectively suppress the rotational vibrations at the top of mast.

Semi-active control of ship mast vibrations using magneto-rheological dampers

Y.S. Cheng,F.T.K. Au,J.P. Zhong 국제구조공학회 2008 Structural Engineering and Mechanics, An Int'l Jou Vol.30 No.6

On marine vessels, delicate instruments such as navigation radars are normally mounted on ship masts. However the vibrations at the top of mast where the radar is mounted often cause serious deterioration in radar-tracking resolution. The most serious problem is caused by the rotational vibrations at the top of mast that may be due to wind loading, inertial loading from ship rolling and base excitations induced by the running propeller. This paper presents a method of semi-active vibration control using magneto-rheological (MR) dampers to reduce the rotational vibration of the mast. In the study, the classical optimal control algorithm, the independent modal space control algorithm and the double input – single output fuzzy control algorithm are employed for the vibration control. As the phenomenological model of an MR damper is highly nonlinear, which is difficult to analyse, a back- propagation neural network is trained to emulate the inverse dynamic characteristics of the MR damper in the analysis. The trained neural network gives the required voltage for each MR damper based on the displacement, velocity and control force of the MR damper quickly. Numerical simulations show that the proposed control methods can effectively suppress the rotational vibrations at the top of mast.

A novel evidence theory model and combination rule for reliability estimation of structures

Y.R. Tao,Q. Wang,L. Cao,S.Y. Duan,Z.H.H. Huang,G.Q. Cheng 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.62 No.4

Due to the discontinuous nature of uncertainty quantification in conventional evidence theory(ET), the computational cost of reliability analysis based on ET model is very high. A novel ET model based on fuzzy distribution and the corresponding combination rule to synthesize the judgments of experts are put forward in this paper. The intersection and union of membership functions are defined as belief and plausible membership function respectively, and the Murfhy’s average combination rule is adopted to combine the basic probability assignment for focal elements. Then the combined membership functions are transformed to the equivalent probability density function by a normalizing factor. Finally, a reliability analysis procedure for structures with the mixture of epistemic and aleatory uncertainties is presented, in which the equivalent normalization method is adopted to solve the upper and lower bound of reliability. The effectiveness of the procedure is demonstrated by a numerical example and an engineering example. The results also show that the reliability interval calculated by the suggested method is almost identical to that solved by conventional method. Moreover, the results indicate that the computational cost of the suggested procedure is much less than that of conventional method. The suggested ET model provides a new way to flexibly represent epistemic uncertainty, and provides an efficiency method to estimate the reliability of structures with the mixture of epistemic and aleatory uncertainties.

China's Modernization Program in the 1980s

Joseph Y.S. CHENG THE INSTITUTE OF EAST AND WEST STUDIES YONSEI UNIV 1989 Global economic review Vol.18 No.2

In the foreseeable future, the first generation of revoluntionary leaders will remain a formidable force in Chinese politics, irrespective of whether they have formally retired or not. Deng will maintain his final arbiter role, while attempts will continue to be made to cultivate a second-tier collective leadership and a third-tier one, with a proper balance of conservatives and reformers endorsed by the first generation leaders. As long as Deng is presiding, political struggles will be limited to jockeying for position, especially in the propaganda and public security arenas. The best scenario is that the reformers'base will be gradually strengthened by sustained economic growth which will in turn provide the legitimacy for the reforms. Various accountability systems and the increasing reliance on the market mechanism will enlarge individual liberties. Short of a direct challenge to the ultimate control of the Party, freedom of speech and publication will be gradually tolerated. Sustained economic growth to some extent will depend on the satisfactory removal of the bottlenecks in the energy. transport and other sectors and the continued inflow of Wetern capital and technology. An international economic recession will hit China like most third world countries as it is no longer insulated from the international capitalist system, while rising protectionism will frustrate its efforts to expand exports in order to pay for its imports. The Chinese leadership certainly recognizes that the legitimacy of the regime now depends on its ability to improve the people's living standards. However, prospects for further political and economic reforms tend to be sluggish as they will be the outcome of a process of compromise and accommodation rather than a commonly accepted general policy program. An overheated economy with its accompanying inflation and economics dislocation and the leadership succession problem remain the major threats to the reformers. The key issue is to maintain the momentum of reforms so as to avoid the failure of Nikita Khrushchev and other East European leaders.

Factors associated with critical thinking cognitive skills among students studying in associate degree in health-related study prior to admission to nursing programs

S.Y. Ng,K. Cheung,H.L. Cheng 한국간호과학회 2021 한국간호과학회 학술대회 Vol.2021 No.10

The importance of fostering critical thinking (CT) in nursing education is highly recognized worldwide. Despite this, CT studies of Asian nursing students are limited, particularly for students studying associate degree (AD) in health-related studies, with whom majority would continue their studies in nursing after graduation. Aim(s): To investigate CT abilities and dispositions among these AD students and to determine the associated factors with their CT cognitive skills. Method(s): A convenience sample of 80 health-related AD students from a community college in Hong Kong were recruited in this cross-sectional study. The valid and reliable study questionnaire included the California Critical Thinking Skills Test (CCTST), the California Critical Thinking Disposition Inventory (CCTDI), and students’ profiles. Correlation analysis was performed by using SPSS 26.0. Result(s): The mean age of the students was 19.38±0.97, with 67.5% (n=54) were female. The mean CCTST scores was 17.93±4.23 and the five subscales: induction, deduction, analysis, inference and evaluation were all in moderate level. The mean CCTDI score was 277.76±20.78 and positive disposition towards CT was shown in only four subscales: open-mindedness, analyticity, confidence in reasoning and inquisitiveness. There was a significant moderate correlation between students’ overall CCTST scores and other variables including university admission examination total score (r=0.260, p<0.001), Chinese score (r=0.136, p=0.049), GPA (r=0.166, p=0.016), CT subject grade point (r=0.226, p=0.001) and CCTDI subscales: truth seeking (r=0.251, p<0.001), analyticity (r=0.208, p=0.003), inquisitiveness (r=0.200, p=0.004) and maturity of judgement (r=0.249, p<0.001). Conclusion(s): This is probably the first study to investigate the CT among AD students studying in health-related studies. The results showed that the factors associated with their CT cognitive skills were multifactorial. Strategies tackling these factors should be developed to strengthen their CT. Future studies should also involve more community colleges.