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Experimental Study of Transition and Stability in Taylor-Couette Flow
Xin Cheng Tu,Dong Liu,Hyoung-Bum Kim(김형범) 한국가시화정보학회 2010 한국가시화정보학회 학술발표대회 논문집 Vol.2010 No.11
The confined fluid flow in a gap between an inner rotating cylinder and an outer stationary cylinder wasexperimentally investigated by using digital particle image velocimetry. Based on the analysis of velocity fields by DPIV, we observed the flow change of the transition zone from circular Couette flow (CCF) to Taylor vortex flow (TVF). The proper orthogonal decomposition (POD) technique was applied to detect the onset of transition process and dominant flow structure in the transition zone. The quantitative characteristics of transition zone were proposed by processing the oscillation characteristics of vortices.
Xin Cheng,Jinpeng Zhu,Zhijie Chen,Zhihao Wu,Fuqiang Zhang,Cai-e Wu,Gong-Jian Fan 한국식품과학회 2023 Food Science and Biotechnology Vol.32 No.10
To evaluate the storage stability of anthocyanin in stirred yoghurt, mulberry juice and different starter cultures (S) were added into milk to investigate the color stability and degradation kinetics of anthocyanin. The result showed that the redness value decreased, while the brightness value increased, and the anthocyanin content decreased significantly from 1.47 ~ 1.86 to 1.01 ~ 1.19 mg/g. The degradation kinetics followed a first-order reaction. Principal component analysis showed that S2 and S6 were correlated with anthocyanins, S8 and S4 were correlated with a*. At the later stage, S4, S8 were correlated with a*, while S2, S4, S6 were correlated with anthocyanins. At 28th day, the anthocyanin content of S4 was 1.14 mg/g, which was not the highest, but the total score was the highest. Therefore, S4 was the best choice when the storage period is 28 days. This study provided technical support for the selection of a better starter for stirring yoghurt.
Xin-feng Cheng,Min Zhang,Benu Adhikari 한국식품과학회 2014 Food Science and Biotechnology Vol.23 No.4
The effects of different freezing and thawingmethods on the physicochemical indices and nutritive valueof edamame [Glycine max (L.) Merrill] were investigated. Air-blast freezing had less of an impact on the drip loss,color, chlorophyll and ascorbic acid contents, and texturalhardness of frozen shelled edamames. Ultrasound-assistedthawing significantly (p<0.05) shortened thawing time,compared to water immersion thawing. Ultrasound-assistedthawing at a 900 W power level showed the best retentionof ascorbic acid and chlorophyll, and original hardness,and minimized the drip loss of thawed samples. Ultrasonicassisted thawing at a power level of 1,200 W caused themost pronounced loss of ascorbic acid. A combination offast air-blast freezing and ultrasound-assisted thawing at apower level of 900 W most effectively retained ascorbicacid and chlorophyll, minimized drip loss, and maintainedthe textural hardness of shelled edamame samples.
Study on Ultimate Capacity of Steel H-Section Members Under Combined Biaxial Bending and Axial Force
Cheng Xin,Wang Xiaxin,Zhang Chao,Duan Dexin 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.5
The ultimate resistance of steel H-section members under biaxial bending and compression has been discussed in the present paper. Finite element models taking account of geometrical and material nonlinearities are established and validated by previous laboratory test results. A series of parametric studies are then conducted considering diff erent loading angles and a spectrum of fl ange width-to-thickness ratios, web width-to-thickness ratios and axial force ratios. An improved energy infl ection method (EIM), which is verifi ed by comparing the analytical results with numerical results, is proposed in order to determine the ultimate state of the members under biaxial bending. It is shown that the ultimate state determined by EIM occurs when the sectional stress distribution reaches the envelop line. Finally, a simple interaction formula is proposed to predict the ultimate capacity of the steel H-section columns subjected to biaxial bending and compression. It is verifi ed that the interaction formula can provide a satisfactory prediction, in comparison against the European code which tends to off er a relatively conservative estimate. The proposed method is applicable to fl ange width-to-thickness ratios ranging from 8 to 28, web width-to-thickness ratios changing from 30 to 120, and axial force ratios varying from 0 to 0.4.
FASHION BLOGS: EFFECTS OF BLOGGING MOTIVATION AND SOCIAL CAPITALON ATTITUDE AND BLOG ENGAGEMENT
Xin Zeng,Jiyoung Kim,Kiseol Yang,Hwa-Ping Cheng 글로벌지식마케팅경영학회 2016 Global Marketing Conference Vol.2016 No.7
While it was found that consumers’ experience on purchase intention is significantly affected by greater involvement in blogging (Hsu & Tsou, 2011), not many fashion companies use blogs to improve online consumption and relationship with their employee or customer (Fieseler & Fleck, 2013). Further, despite the growing significance of blog communication, there is a lack of understanding for the impact of accumulation of social capital in the blogosphere on the consumers’ attitude and engagement in previous research. This study is designed to address this gap, and particularly the role of three dimensions of social capital (i.e., structural, relational, and cognitive) in understanding blog user’s attitude and engagement. The purpose of this study is to investigate 1) the effect of blog user’s motivation (i.e., perceived usefulness, perceived ease of use, reputation, altruism, enjoyment, community identification) on their level of social capital within the blog 2) the influence of structural social capital and cognitive social on user’s relational social capital and 3) the impact of relational social capital on blog user’s attitude and engagement. Data was collected through a marketing research firm utilizing online survey method. With 530 usable data, the results of this study indicated enjoyment have positive significant effect on structural social capital while community identification have negative significant effect on structural social capital. For the effect of blogging motivation on cognitive social capital, the result showed positive significant effect of perceived usefulness, altruism and community identification on cognitive social capital Further, structural social capital does not have relationship with relational social capital while cognitive social capital has significant effect on relational social capital. The results also indicated that the relational social capital has influence on blogging attitude, which in turn has strong positive relationship with blogging engagement. The findings of this study contribute some useful knowledge about fashion blog and the relationships of the three social capital dimensions to the literature. Also, this study not only provides theoretical insight into understanding the influence of fashion blog user’s motivation on blogging behavior and satisfaction of needs of belong, it also exposes the influence of relationships building in blog community on user’s blogging attitude and engagement. Previous studies focused more on social influence on knowledge sharing motivation, and most of the researchers paid attention to the interaction of cognitive social capital and relational capital. This study employs the knowledge sharing motivation findings of previous studies, and it uses the effective motivation factors to test if they have the same impacts on people’s blogging behavior.
A dynamic asymmetrical crack model of bridging fiber pull-out in unidirectional composite materials
Xin-gang Li,Yun-hong Cheng,Nian-chun Lü,Guo-dong Hao,Jin Cheng 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.9
As a rule, when a crack happens in composite materials, the fibrous system will generate bridging fibers resulted in the asymmetrical extending of the crack. In this paper, a dynamic asymmetrical crack model of bridging fiber pull-out in unidirectional composite materials is built for analyzing the distributions stress and displacement with the internal asymmetrical crack under the loading conditions of an applied non- stress and the traction forces on crack faces yielded by the bridging fiber pull-out model. Thus the fiber failure is determined by the maximum tensile stress, the fiber ruptures, and hence the crack propagation should also occur in self-similar modality. The formulation involves the development of a Riemann-Hilbert problem. The analytical solution of an asymmetrical extension crack in unidirectional composite materials under the conditions of moving increasing loads Pt²/x² and Px²/t is concluded, respectively. Based on relative material properties, the variable law of dynamic stress intensity factors was depicted perfectly. After the conclusion of analytical solutions with the superposition theorem, the solutions of arbitrary complex problems could be acquired.