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Search Results: 1 - 10 of 108464 matches for " Jun Chen "
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Computing the Moore-Penrose Inverse of a Matrix Through Symmetric Rank-One Updates  [PDF]
Xuzhou Chen, Jun Ji
American Journal of Computational Mathematics (AJCM) , 2011, DOI: 10.4236/ajcm.2011.13016
Abstract: This paper presents a recursive procedure to compute the Moore-Penrose inverse of a matrix A. The method is based on the expression for the Moore-Penrose inverse of rank-one modified matrix. The computational complexity of the method is analyzed and a numerical example is included. A variant of the algorithm with lower computational complexity is also proposed. Both algorithms are tested on randomly generated matrices. Numerical performance confirms our theoretic results.
Service Cooperation Policy in a Dual-Channel Supply Chain under Service Differentiation  [PDF]
Jun Chen, Ying Yang
American Journal of Industrial and Business Management (AJIBM) , 2014, DOI: 10.4236/ajibm.2014.46036

A service collaboration decision problem in a dual-channel supply chain is studied with the service level and the customer’s acceptance of the Internet channel is taken into consideration. Then the Stackelberg decentralized decision model and the centralized decision model are developed for two settings that the retailer provides the same service level in both channels or not. The conclusion implies that the system profits, the manufacturer’s optimal profit and retailer’s optimal profit are always higher when different services are provided than the same service, and the optimal service level for the direct channel is a little lower than that for the traditional channel under decentralized mode.

Worker Recruiting with Favoritism and Bribery  [PDF]
Gen Chen, Jun Tang
Theoretical Economics Letters (TEL) , 2015, DOI: 10.4236/tel.2015.53048
Abstract: This paper discusses the corruptive action widespread in the organizations’ worker recruiting: favoritism and bribery. The managers of the firm are actually able to discern the type of the productivity of the job-seekers, but they utilize the information advantage through the two types of misconduct—favoritism and bribery, at the expense of the profit share of the principal (the owner) and the workers’ wage rent. The key conclusion is drawn from this paper as follows: neither the intensity of favoritism nor the wage level matters in determining whether there’s profit or loss in the firm, whereas the key variable is the relative situation of exterior labor market.
Quasi-Bézier Curves with Shape Parameters
Jun Chen
Journal of Applied Mathematics , 2013, DOI: 10.1155/2013/171392
Favorable and Unfavorable Characteristics of EFL Teachers Perceived by University Students of Thailand
Jun Chen
International Journal of English Linguistics , 2012, DOI: 10.5539/ijel.v2n1p213
Abstract: Teachers play pivotal roles in EFL classrooms. Characteristics of EFL teachers may affect students’ attitudes and motivations to language learning. The effective/good characteristics of the EFL teachers perceived by the students have been extensively investigated by the previous research works. However, the perceptions of the students from different backgrounds to EFL teachers may vary in different learning settings. In addition, the research works on both favorable and unfavorable characteristics of EFL teachers are comparatively scarce. This study aimed to investigate the favorable and unfavorable characteristics of the EFL teachers perceived by Thai university students. The data were collected from 6o students at Vongchavalitkul University. Open-ended questionnaires and semi-structured interviews were used as the main instruments for data collection. Useful information about EFL teachers’ personal trait-related characteristics and classroom teaching-related characteristics emerged from the data. The information is very useful and beneficial for the EFL teachers to reflect their personal characteristics and reconsider their classroom teaching, which may be very helpful for them to do some adjustment and preparation in their teaching to achieve better education results.
Subsonic Flows for the Full Euler Equations in Half Plane
Jun chen
Mathematics , 2007,
Abstract: We study the subsonic flows governed by full Euler equations in the half plane bounded below by a piecewise smooth curve asymptotically approaching x1-axis. Nonconstant conditions in the far field are prescribed to ensure the real Euler flows. The Euler system is reduced to a single elliptic equation for the stream function. The existence, uniqueness and asymptotic behaviors of the solutions for the reduced equation are established by Schauder fixed point argument and some delicate estimates. The existence of subsonic flows for the original Euler system is proved based on the results for the reduced equation, and their asymptotic behaviors in the far field are also obtained.
A Class of Multi-particle Reinforced Interacting Random Walks
Jun Chen
Mathematics , 2012,
Abstract: We consider a class of multi-particle reinforced interacting random walks. In this model, there are some (finite or infinite) particles performing random walks on a given (finite or infinite) connected graph, so that each particle has higher probability to visit neighboring vertices or edges which have been seldom visited by the other particles. Specifically we investigate two particles' vertex-reinforced interacting random walks on finite complete graphs. By a dynamical approach we prove that the two particles' occupation measure asymptotically has small joint support almost surely if the reinforcement is strong.
Spectral Geometric Triangle Properties of Chlorophyll-A Inversion in Taihu Lake Based on TM Data  [PDF]
Jun Chen, Zhenhe Wen, Zhengqing Xiao
Journal of Water Resource and Protection (JWARP) , 2011, DOI: 10.4236/jwarp.2011.31008
Abstract: The main objective of this study was to develop and validate the applicability of the Area Chlorophyll-a Concentration Retrieved Model (ACCRM), Height Chlorophyll-a Concentration Retrieved Model (HCCRM), Angle Chlorophyll-a Concentration Retrieved Model (AgCCRM), and Ratio Model of TM2/TM3 (RM) in estimating the chlorophyll-a concentration in Case II water bodies, such as Taihu Lake in Jiangsu Province, China. Water samples were collected from 23 stations on the 27th and 28th of October, 2003. The four empirical models were calibrated against the calibration dataset (samples from 19 stations) and validated using the validation dataset (samples from 4 stations). The regression analysis showed higher correlation coefficients for the ACCRM and the HCCRM than for the AgCCRM and the Ratio Model; and the HCCRM was slightly superior to the ACCRM. The performance of the ACCRM and the HCCRM was validated, and the ACCRM underestimated concentration values more than the HCCRM. The distribution of chlorophyll-a concentrations in Taihu Lake on October 27, 2003 was estimated based on the Landsat/TM data using the ACCRM and the HCCRM. Both models indicated higher chlorophyll-a concentrations in the east, north and center of the lake, but lower concentrations in the south. The accuracy of results obtained from the HCCRM and the ACCRM were also supported by the validation dataset. The study revealed that the HCCRM and the ACCRM had the best potential for accurately assessing the chlorophyll-a concentration in the highly turbid water bodies.
Numerical Simulation for Shaping Feature of Molten Pool in Twin-Arc Submerged Arc Welding  [PDF]
Kuanfang He, Jun Chen, Siwen Xiao
Open Journal of Applied Sciences (OJAppS) , 2012, DOI: 10.4236/ojapps.2012.21005
Abstract: The notion of ratio of width to length is proposed to describe the shaping feature of molten pool of twin-Arc submerged arc welding accurately, and analyze the law of molten pool variation and weld formation. The temperature field finite element numerical simulation model of twin arc movement is established. The loading form of twin-arc with double ellipsoid heat source is discussed. The molten pool temperature field of twin-arc submerged arc welding is calculated and analyzed under different process parameters. The law of molten pool characteristics influenced by the welding speed, current and voltage of twin-arc submerged arc welding parameters is analyzed. The relation between shaping feature of molten pool and weld formation is discussed according to the ratio of width to length. The results manifested that the width to length ratio of weld pool decreases with the improvement of welding speed, which result in gene- ration of weld defects. The width to length ratio of weld pool is increased by adjusting the proportion of the current, voltage and the distance of the two arcs, which avoids the generation of weld defects.
The effects of comprehensive nursing interventions on sexual functions in young and middle-aged patients with coronary stent implantation  [PDF]
Hong Zhang, Gehui Zhu, Jun Chen
Health (Health) , 2013, DOI: 10.4236/health.2013.511A2001
Abstract: Objective: To study the effects of comprehensive nursing interventions on sexual functions in young and middle-aged patients with coronary stent implantation. Methods: 96 cases of coronary stent implantation were randomly divided into control group and intervention group (experimental group) with each group of 48 cases. The control group received the routine nursing measures after the coronary stent implantation and the experimental group was treated by the comprehensive nursing interventions such as psychological nursing, education of sexual knowledge, playing the full enthusiasm of spouse and appropriate exercise therapy on basis of the routine nursing measures. The two groups were given the questionnaire of brief male sexual function questionnaire (BSFI), Chinese patients with premature ejaculation sexual function score (C-ISFPE) and the international index of erectile function (IIEF-5). The scores of BSFI, C-ISFPE and IIEF-5 were compared between the two groups. Results: There were 29 cases who were satisfied with sexual life on the whole (≤1), 26 cases with different degrees of premature ejaculation symptoms and 21 cases with erectile dysfunctions, which were respectively 27.08%, 30.2% and 21.87% of the total number. The scores of BSFI, C-ISFPE and IIEF-5 inthe experimental group were significantly increased after the interventions (P < 0.05). The BSFI scores of the experimental group were significantly higher than those of the control group (P < 0.05) and the C-ISFPE and IIEF-5 scores in the two groups were significantly different (P < 0.05). Conclusions: The comprehensive nursing interventions can effectively improve the sexual functions and enhance the quality of life of young and middle-aged patients with coronary stent implantation.

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