Numerical Study on Key Parameters of Magnetorheological Fluid Reciprocating Seal with Four Magnetic Sources

Xiao-long Yang,Fu-xiang Hao,Peng Sun 한국자기학회 2020 Journal of Magnetics Vol.25 No.2

In order to improve the pressure capability of Magnetorheological fluid (MRF) reciprocating seal with four magnetic sources, MRF reciprocating seal structure was designed based on the formula of MRF reciprocating seal. The magnetic field distributons in the sealing gap of MRF reciprocating seals were analyzed by using finite element analysis of magnetic field. The influences of structure parameters such as sealing gap, ratio of permanent magnet height to length, ratio of pole tooth length to width, ratio of slot width to pole tooth width and ratio of pole piece height to the shaft radius on the sealing capabilities were studied. The results were analyzed and discussed. The results show that the pressure capability of MRF seal decreases significantly with the increase of sealing gap. The pressure capability of the MRF seal increases firstly and then decreases with the increase in the ratio of permanent magnet height to its length. The pressure capability of the MRF seal increases firstly and then decreases with the increase in the ratio of pole tooth length to its width. The pressure capability of the MRF seal increases firstly and then decreases with the increase in the ratio of slot width to pole teeth width. The pressure capability of MRF seal decreases with the increase in the ratio of pole piece height to shaft radius.

Numerical and Experimental Study on Strain Rate Effect of Ordinary Concrete under Low Strain Rate

Xiao Chen,Chong Shi,Yu-Long Zhang,Jun-Xiong Yang 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.5

The strain rate effect of ordinary concrete is researched through the particle discrete element method. A random construction method of three-dimensional aggregate is used, and the numerical sample consistent with the experimental specimen is constructed using particle flow code. Moreover, the simulation method that can properly reflect the strain rate effect with the parallel bond model is proposed. The meso-parameters are calibrated by triaxial compression test. Based on the proposed simulation method and calibrated meso-parameters, the numerical tests of direct tension, uniaxial compression, and cyclic loading under strain rates from 10−5 s−1 to 10−1 s−1 are carried out. The results show that the strain rate effect of concrete can be simulated with particle flow code by assuming that the micromechanical properties of materials vary with the strain rate, and the strength and failure characteristics of numerical samples under different strain rates are described well by the proposed method. In addition, the different mechanical responses of the samples to the strain rate in the compression test and the tensile test are obtained, and the changes of mechanical parameters and damage degree with strain rates in the cyclic loading test are also successfully simulated. This study can provide a feasible numerical method for the follow-up research of dynamic mechanical behavior of concrete and offer theoretical guidance for the stability assessment of concrete engineering.

Comparative proteomic analysis of proteins expression changes in the mammary tissue of cows infected with Escherichia coli mastitis

Xiao-wei Zhao,Yong-xin Yang,Dong-wei Huang,Guang-long Cheng,Hui-ling Zhao 대한수의학회 2015 Journal of Veterinary Science Vol.16 No.3

Cows infected with Escherichia (E.) coli usually experience severe clinical symptoms, including damage to mammary tissues, reduced milkyield, and altered milk composition. In order to investigate the host response to E. coli infection and discover novel markers for mastitistreatment, mammary tissue samples were collected from healthy cows and bovines with naturally occurring severe E. coli mastitis. Changesof mammary tissue proteins were examined using two-dimensional gel electrophoresis and label-free proteomic approaches. A total of 95differentially expressed proteins were identified. Of these, 56 proteins were categorized according to molecular function, cellular component,and biological processes. The most frequent biological processes influenced by the proteins were response to stress, transport, andestablishment of localization. Furthermore, a network analysis of the proteins with altered expression in mammary tissues demonstrated thatthese factors are predominantly involved with binding and structural molecule activities. Vimentin and -enolase were central “functionalhubs” in the network. Based on results from the present study, disease-induced alterations of protein expression in mammary glands andpotential markers for the effective treatment of E. coli mastitis were identified. These data have also helped elucidate defense mechanismsthat protect the mammary glands and promote the pathogenesis of E. coli mastitis.

Application of Constant Rate of Velocity or Pressure Change Method to Improve Annular Jet Pump Performance

Yang, Xuelong,Long, Xinping,Kang, Yong,Xiao, Longzhou Korean Society for Fluid machinery 2013 International journal of fluid machinery and syste Vol.6 No.3

To improve annular jet pump (AJP) performance, new ways named constant rate of velocity/pressure change method (CRVC/CRPC) were adopted to design its diffuser. The design formulas were derived according to the assumption of linear velocity/pressure variation in the diffuser. Based on the two-dimensional numerical simulations, the effect of the diffuser profile and the included angle on the pump performance and the internal flow details has been analyzed. The predicted results of the RNG k-epsilon turbulence model show a better agreement with the experiment data than that of the standard and the realizable k-epsilon turbulence models. The AJP with the CRPC diffuser produces a linear pressure increase in the CRPC diffuser as expected. The AJP with CRPC/CRVC diffuser has better performance when the diffuser included angle is greater or the diffuser length is shorter. Therefore, the AJP with CRPC/CRVC diffuser is suitable for applications requiring space limitation and weight restriction.

Consumption Motivations for Counterfeit Luxury Brands: Moderating Role of Genuine Brand Experience

Xiao-Long Yin,Yan-Li Yang,Hyung-Jun Kim 한국무역연구원 2021 무역연구 Vol.17 No.5

Purpose - In the Chinese market, increasing numbers of luxury brands are overwhelmed by counterfeits, and the continued success of counterfeits has become a considerable problem. Therefore, this research is to understand the purchase motivations for the counterfeits in the Chinese millennial generation, who are the main force of Chinese luxury brand market and counterfeits market. Design/Methodology/Approach - The data comes from a questionnaire survey from Chinese millennials (N= 391). This study uses the regression analysis and moderation effect model to verify causal relations or compare the difference in particular circumstances. Findings - Among the 8 variables, only 5 motivation factors influence purchase intention of counterfeits. The moderating effect of perceived risk was significant only when Mianzi influences the purchase intention of counterfeits. Millennials without experience in genuine brand more tend to buy counterfeits when they are motivated by conspicuous, Mianzi, and materialism reasons. Conversely, consumers with experience are more likely to buy counterfeits mainly when materialism, bandwagon, and Mianzi motivations become important. Notably, men also purchased counterfeits because of Mianzi or self-gift giving than women, the motivations for buying the counterfeits were more diverse relatively in case of middle-incomers. Research Implications - This study introduced the motivations of core consumer psychology factors into the analysis of counterfeits. The results will provide the theoretical basis for global luxury brand managers facing the Chinese market when formulating sustainable development strategies.

Electrochemical machining with pulsating electrolyte flow

Xiao-long Fang,Ning-song Qu,Zheng-yang Xu 한국생산제조학회 2014 한국생산제조시스템학회 학술발표대회 논문집 Vol.2014 No.9(2)

Numerical investigation on the recirculation in annular jet pumps

Longzhou Xiao,Xinping LONG,Xiaohong Li,Qinglong Zeng,Xuelong Yang 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.6

The flow within the annular jet pump (AJP), in some degree, resembles the annular wall jet developing in a pipe with great axial pressure gradient. In some working conditions, there exists the backflow near the centerline. However this differs from the case in a center jet pump (CJP) that the recirculation emerges near the inner wall of the throat. The recirculation in AJP affects a lot to its performance, especially when AJP is utilized to convey something alive, such as fish. This paper aims to numerically study the impact of two parameters, the flow ratio M and the area ratio A, on the location, size and formation of the recirculation in AJP. After being validated by the experimental results, the RNG k-ε turbulent model was adopted. It is found that: (1) As M increases, the width and height of the recirculation in AJP decreases, and the separation point of the recirculation shifts gradually far away from the nozzle exit while the reattachment point slightly moves; (2) As A becomes larger, the width and height of the recirculation enlarged, with M keeping constant; (3) For AJP with constant A, the recirculation emerges when M declines to a critical value, and the value varies linearly with A; (4) The Craya-Curtet number Ct and the momentum ratio J, which take A and M into whole consideration, are also feasible in describing the disappearance of the recirculation. However the critical value of Ct and J are different from that discovered in CJP. The critical Ct increases with decreasing A and the critical momentum ratio Jc experiences a linear relationship with A.

Sodium tanshinone IIA sulfonate attenuates angiotensin II-induced collagen type I expression in cardiac fibroblasts in vitro

Le Yang,Xiao-Jing Zou,Xiang Gao,Hao Chen,Jin-Long Luo,Zhao-Hua Wang,Qian-Sheng Liang,Guang-Tian Yang 생화학분자생물학회 2009 Experimental and molecular medicine Vol.41 No.7

Cardiac fibrosis occurs after pathological stimuli to the cardiovascular system. One of the most important factors that contribute to cardiac fibrosis is angiotensin II (Ang II). Accumulating studies have suggested that reactive oxygen species (ROS) plays an important role in cardiac fibrosis and sodium tanshinone IIA sulfonate (STS) possesses antioxidant action. We therefore examined whether STS depresses Ang II-induced collagen type I expression in cardiac fibroblasts. In this study, Ang II significantly enhanced collagen type I expression and collagen synthesis. Meanwhile, Ang II depressed matrix metalloproteinase- 1 (MMP-1) expression and activity. These responses were attenuated by STS. Furthermore, STS depressed the intracellular generation of ROS, NADPH oxidase activity and subunit p47phox expression. In addition, N-acetylcysteine the ROS scavenger, depressed effects of Ang II in a manner similar to STS. In conclusion, the current studies demonstrate that anti-fibrotic effects of STS are mediated by interfering with the modulation of ROS. Cardiac fibrosis occurs after pathological stimuli to the cardiovascular system. One of the most important factors that contribute to cardiac fibrosis is angiotensin II (Ang II). Accumulating studies have suggested that reactive oxygen species (ROS) plays an important role in cardiac fibrosis and sodium tanshinone IIA sulfonate (STS) possesses antioxidant action. We therefore examined whether STS depresses Ang II-induced collagen type I expression in cardiac fibroblasts. In this study, Ang II significantly enhanced collagen type I expression and collagen synthesis. Meanwhile, Ang II depressed matrix metalloproteinase- 1 (MMP-1) expression and activity. These responses were attenuated by STS. Furthermore, STS depressed the intracellular generation of ROS, NADPH oxidase activity and subunit p47phox expression. In addition, N-acetylcysteine the ROS scavenger, depressed effects of Ang II in a manner similar to STS. In conclusion, the current studies demonstrate that anti-fibrotic effects of STS are mediated by interfering with the modulation of ROS.

Association between Cigarette Smoking and RASSF1A Gene Promoter Hypermethylation in Lung Cancer Patients: a Meta-analysis

Wu, Xiao-Ming,Chen, Yu,Shao, Yang,Zhou, Xiao-Long,Tang, Wen-Ru Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.19

Objectives: Epidemiological studies have shown that molecular mechanisms underlying the development of lung cancers differ between smokers and unsmokers. Aberrant promoter methylation in some tumor suppressor genes is frequent in lung tumors from smokers but rare in those from non-smokers. Recently, many studies have investigated the association between cigarette smoking and RASSF1A gene promoter hypermethylation in lung cancer patients, but a unanimous conclusion could not be reached. We therefore performed this meta-analysis to derive a more precise estimation of any association. Study Design: An electronic search of PubMed and Chinese Biomedicine databases was conducted to select studies. A total of 19 case-control studies were chosen, and odds ratios (ORs) with confidence intervals (CIs) were used to assess the strength of associations. Results: The case-control studies covered 2, 287 lung cancer patients: 63.4%(1449) of the patients were smokers, 36.6% (838) were unsmokers. The overall results suggested that smokers with lung cancer had a 1.297-fold (95% CI: 1.066~1.580, p=0.010, p=0.087) higher risk for RASSF1A gene hypermethylation than the non-smokers. In the stratified analysis, an increased risk of RASSF1A gene hypermethylation in smokers than in non-smokers was found in Asian (OR=1.481, 95%CI: 1.179~1.861, p=0.001, p=0.186). Conclusions: This meta-analysis supports the idea that RASSF1A gene hypermethylation is associated with cigarette smoking-induced lung cancer.

Application of Constant Rate of Velocity or Pressure Change Method to Improve Annular Jet Pump Performance

Xuelong Yang,Xinping LONG,Yong Kang,Longzhou Xiao 한국유체기계학회 2013 International journal of fluid machinery and syste Vol.6 No.3

To improve annular jet pump (AJP) performance, new ways named constant rate of velocity/pressure change method (CRVC/CRPC) were adopted to design its diffuser. The design formulas were derived according to the assumption of linear velocity/pressure variation in the diffuser. Based on the two-dimensional numerical simulations, the effect of the diffuser profile and the included angle on the pump performance and the internal flow details has been analyzed. The predicted results of the RNG k-epsilon turbulence model show a better agreement with the experiment data than that of the standard and the realizable k-epsilon turbulence models. The AJP with the CRPC diffuser produces a linear pressure increase in the CRPC diffuser as expected. The AJP with CRPC/CRVC diffuser has better performance when the diffuser included angle is greater or the diffuser length is shorter. Therefore, the AJP with CRPC/CRVC diffuser is suitable for applications requiring space limitation and weight restriction.