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102. The influence of Ac parameters in the process of micro-arc oxidation film electric breakdown

Author

Ma Jin

Subjects
micro-arc oxidation, AC parameter, solid dielectric, gas film, break down, Engineering (General). Civil engineering (General), TA1-2040
Abstract

This paper studies the electric breakdown discharge process of micro-arc oxidation film on the surface of aluminum alloy. Based on the analysis of the AC parameters variation in the micro-arc oxidation process, the following conclusions can be drawn: The growth of oxide film can be divided into three stages, and Oxide film breakdown discharge occurs twice in the micro-arc oxidation process. The first stage is the formation and disruptive discharge of amorphous oxide film, producing the ceramic oxide granules, which belong to solid dielectric breakdown. In this stage the membrane voltage of the oxide film plays a key role; the second stage is the formation of ceramic oxide film, the ceramic oxide granules turns into porous structure oxide film in this stage; the third stage is the growth of ceramic oxide film, the gas film that forms in the oxide film’s porous structure is electric broken-down, which is the second breakdown discharge process, the current density on the oxide film surface could affect the breakdown process significantly.

Published
2016
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103. On residents’ satisfaction with community health services after health care system reform in Shanghai, China, 2011

Author

Li Zhijian, Hou Jiale, Lu Lin, Tang Shenglan, and Ma Jin

Subjects
Public aspects of medicine, RA1-1270
Abstract

Abstract Background Health care system reform is a major issue in many countries and therefore how to evaluate the effects of changes is incredibly important. This study measured residents’ satisfaction with community health care service in Shanghai, China, and aimed to evaluate the effect of recent health care system reform. Methods Face-to-face interviews were performed with a stratified random sample of 2212 residents of the Shanghai residents using structured questionnaires. In addition, 972 valid responses were retrieved from internet contact. Controlling for sex, age, income and education, the study used logistic regression modeling to analyze factors associated with satisfaction and to explain the factors that affect the residents’ satisfaction. Results Comparing current attitudes with those held at the initial implementation of the reform in this investigation, four dimensions of health care were analyzed: 1) the health insurance system; 2) essential drugs; 3) basic clinical services; and 4) public health services. Satisfaction across all dimensions improved since the reform was initiated, but differences of satisfaction level were found among most dimensions and groups. Residents currently expressed greater satisfaction with clinical service (average score=3.79, with 5 being most satisfied) and the public health/preventive services (average score=3.62); but less satisfied with the provision of essential drugs (average score=3.20) and health insurance schemes (average score=3.23). The disadvantaged groups (the elderly, the retired, those with only an elementary education, those with lower incomes) had overall poorer satisfaction levels on these four aspects of health care (P Conclusion The respondents showed more satisfaction with the clinical services (average score=3.79) and public health services/interventions (average score=3.79); and less satisfaction with the health insurance system (average score=3.23) and the essential drug system (average score=3.20). Disadvantaged groups showed lower satisfaction levels overall relative to non-disadvantaged groups.

Published
2012
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110. A General Conditional McKean-Vlasov Stochastic Differential Equation

Author

Buckdahn, Rainer, Li, Juan, and Ma, Jin

Subjects
Mathematics - Probability
Abstract

In this paper we consider a class of {\it conditional McKean-Vlasov SDEs} (CMVSDE for short). Such an SDE can be considered as an extended version of McKean-Vlasov SDEs with common noises, as well as the general version of the so-called {\it conditional mean-field SDEs} (CMFSDE) studied previously by the authors [1, 14], but with some fundamental differences. In particular, due to the lack of compactness of the iterated conditional laws, the existing arguments of Schauder's fixed point theorem do not seem to apply in this situation, and the heavy nonlinearity on the conditional laws caused by change of probability measure adds more technical subtleties. Under some structure assumptions on the coefficients of the observation equation, we prove the well-posedness of solution in the weak sense along a more direct approach. Our result is the first that deals with McKean-Vlasov type SDEs involving state-dependent conditional laws.

Published
2021

132. Microstructure and wear resistance of Fe-Cr-C-Mo-V-Ti-N hardfacing layers

Author

Son, Won Chol, Jong, Yong Gwang, Pak, Myong Chol, and Ma, Jin Song

Subjects
Condensed Matter - Materials Science, Physics - Applied Physics
Abstract

In this paper, to improve wear resistance of components such as screws under severe friction-wear, Fe-Cr-C-Mo-V-Ti-N hardfacing coatings were further developed. The hardfacing coatings were acquired by shielded manual arc welding (SMAW) method. The ferroalloys added into the coating flux of the hardfaced electrode were jointly nitrided. The microstructure of the coatings was carried out using X-ray diffraction(XRD), optical microscope(OM), field emission scanning electron microscope (FESEM) and energy dispersive Xray spectrometry (EDS). In addition, FactSage 7.0 software was employed to calculate the equilibrium phase diagram of the hardfacings. The wear resistance was performed on a pin-on-disc machine. The Fe-Cr-C- Mo-V-Ti-N hardfacings exhibited higher wear resistance than cladding layer without nitrides., Comment: 9 pages, 12 figures

Published
2021

133. Out-of-Step Detection Based On an Improved Line Potential Energy Criterion

Author

Li, Xiao, Liu, Chongru, and Ma, Jin

Subjects
Electrical Engineering and Systems Science - Systems and Control
Abstract

The line potential energy in the cutset is used as the criterion for monitoring the generator instability, but the criterion has the following two limitations due to narrowly defined conditions. The assumption of an ideal constant power load is difficult to satisfy, and the condition of the critical cutset is too narrow. The limitations are addressed by analyzing the relationship between the power of the load elements and the power of the cutset based on the two-machine equivalent. Modifications of the theoretical derivation steps of this criterion are presented to extend the applications of the criterion and provide theoretical support for its online use. Two simple strategies are proposed to ensure early detection of the generator instability., Comment: 11 pages, 12 figures, publish in "electric power system research"

Published
2021
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135. Topic Tracking from Classification Perspective: New Chinese Dataset and Novel Temporal Correlation Enhanced Model

Author

Ma, Jin, Zhang, Xinming, Fang, Yuxun, Zuo, Xinyu, Liang, Haijin, Goos, Gerhard, Founding Editor, Hartmanis, Juris, Founding Editor, Bertino, Elisa, Editorial Board Member, Gao, Wen, Editorial Board Member, Steffen, Bernhard, Editorial Board Member, Yung, Moti, Editorial Board Member, Liu, Fei, editor, Duan, Nan, editor, Xu, Qingting, editor, and Hong, Yu, editor

Published
2023
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