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Rotor dynamics analysis and experiment study of the flywheel spin test system
Tang Chang-Liang 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.9
The strength study of the flywheel is important to the flywheel energy storage. The motor and bearing are the key challenges for the high-speed flywheel spin test device in vacuum. By using a small stiffness pivot-jewel bearing and a spring squeeze film damper as the lower support of the flywheel, a simple spin system was designed at a low cost and is suitable for longtime operation. The auxiliary support at the top was not removed until the flywheel passed the first critical speed. The flywheel that kept its rigid state in sub-critical state was tested at the high speed without the top support. The dynamic model of the flywheel-bearing-damper was built by means of the Lagrangian equation to calculate critical speeds, mode shapes and modal damping ratios at different speeds. The lower damper’s effects on the modal damping ratios and forced vibration were discussed. The vibrations of the flywheel-bearing-damper system were measured at the different damping coefficients in the experiment. When the lower damper was adjusted to be overdamped, the flywheel ran up to 50000 r/min steadily, and the experimental result was in agreement with the theoretical assumption. The sub-critical rotor dynamics design and pivot-jewel bearing proved to be good solutions to the spin test for the composite flywheel.
Dynamic model of four degree of freedom rope-driven rigid-flexible hybrid wave compensation device
Liang Tang,Yuan Chen 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.5
In the process of replenishment at sea, in order to ensure the safety of workers and cargo on the deck, collisions between the cargo and the deck or cargo should be at least reduced if not avoided. Considering the actual situation of the marine environment, a fourdegree-of-freedom rope-driven rigid-flexible hybrid wave compensation mechanism for offshore hoisting equipment is proposed. First, based on the screw theory, the feasibility of a wave compensation mechanism was verified, and the experimental device of the wave compensation mechanism was designed. Then, a positional forward/reverse solution model of the wave compensation mechanism was established based on the algebraic method. Then, the kinematics model of the wave compensation mechanism was derived and the system dynamics model of the wave compensation mechanism was established based on Newton-Eulerian method. The simulation software was used to verify the derived mathematical model. It was found that the positional positive/negative solution error of the wave compensation mechanism was of the order of 10 -5 mm; the MATLAB numerical simulation results and the Adams virtual prototype results of the kinematics and dynamics models were basically consistent. The maximum error was 2.4 % of the theoretical value, which is an acceptable range. The correctness of the derived kinematics and dynamics model was verified. The research results provide a theoretical basis for further performance analysis and motion control of the wave compensation mechanism.
Liang Tang,Xiaoyu Zhang,Xianzhang Ling 대한토목학회 2016 KSCE JOURNAL OF CIVIL ENGINEERING Vol.20 No.2
Installation oF Stone Column (SC) is a promising ground improvement technique to mitigate liquefaction hazards in sand stratum. In this study, a three-dimensional (3D) Finite Element (FE) analysis was used to simulate a centrifuge experiment on the mitigation of silty sand strata liquefaction using SC approach. The predicted response of the silty sand and SC matched the experimental data well. The overall site-stiffening effects due to the installed SCs as well as the distributions of the shear stress and shear stress reductions were evaluated. A parametric study was conducted to investigate the effect of the SC permeability and the surface load at the SC zone on the effectiveness of liquefaction mitigation. The results showed that the SCs behaved in a combined shear and flexure mode. Furthermore, the SCs with permeability exceeding a threshold value can dramatically decrease the liquefaction hazard. On the other hand, larger surface load did not prevent soil liquefaction and produced negligible benefits in stiffening. The present study further enhances the current understanding of the effectiveness of SC remediation approaches in the silty sand.
Liang (Rebecca) Tang,Aikaterini Manthiou,Alastair Morrison,JungYoung Shin,Lanlung Chiang 한국관광학회 2012 International Journal of Tourism Sciences Vol.12 No.1
This study proposes a holistic approach to investigate activity preference patterns of international tourist market in Shanghai, China. The authors establish a second-order factor model of activity preference represented by activity segments. The second-order model is further compared across business and leisure tourist groups. The results indicate that the pattern of the second-order model across business and leisure tourist groups to Shanghai is consistent. The tourists in both groups show the highest interests in seeing local life, followed by entertainment, special tourism, and traditional attractions. This study leads to a more efficient allocation of resources in destination development and provides guidance regarding promotional strategies.
Zhengwei Tang,Aimin Liang,Handong Liang,Jiangwei Zhao,Lin Xu,Jie Zhang 한국고분자학회 2019 Macromolecular Research Vol.27 No.8
This study involves an investigation of the chain transfer reaction of butadiene (Bd) polymerization, under the neodymium tris[bis(2-ethylhexyl)phosphate] (Nd)/diisobutyl aluminum hydride (Al)/ethylaluminum sesquichloride (Cl)/Bd catalytic system. The results show that the chain transfer reaction itself is reversible. Only chain propagation and chain exchange reactions occurred during the later period of polymerization, and there was a linear relationship between the molecular weight and the conversion rate. All polymer chains showed sufficient reactivity to propagate by reacting with the monomer. The degree of the chain transfer reaction can be determined by the amount of Al, and the molecular weight in the synthetic polybutadiene can be accurately designed by the formula Mn=54·Bd/Nd/(0.67Al/Nd-7.17). The catalyst-polymerized butadiene afforded products featuring a relatively narrow molecular weight distribution and a high cis-1,4 stereospecificity. One of these products, polybutadiene rubber, showed narrow distribution in the sample, and exhibited good physical and mechanical properties, low abrasion, and low rolling resistance.
Jiang, Zhi-Liang,Tang, Ya-Fang,Wei, Lin,Liang, Ai-Hui Korean Chemical Society 2011 Bulletin of the Korean Chemical Society Vol.32 No.8
In pH 4.2 HAc-NaAc buffer solution, horseradish peroxidase (HRP) catalyzed $H_2O_2$ oxidation of nanosilver to form $Ag^+$. After centrifugation, $Ag^+$ in the supernatant can be measured by graphite furnace atomic absorption spectrophotometry (GFAAS) at the silver absorption wavelength of 328.1 nm. When HRP concentration increased, the $Ag^+$ concentration in the supernatant increased, and the absorption value enhanced. The HRP concentration in the range of 0.84-50 $ng{\cdot}mL^{-1}$ was linear to the enhanced absorption value (${\Delta}A$), with a regression equation of ${\Delta}A$=0.012C+0.11, correlation coefficient of 0.9988, and detection limit of 0.41 $ng{\cdot}mL^{-1}$ HRP. The proposed GFAAS method was used to detect HRP in waste water samples, with satisfactory results.
Man-Lai Tang,Guo-Liang Tian,Nian-Sheng Tang,Zhenqiu Liu 한국통계학회 2009 Journal of the Korean Statistical Society Vol.38 No.4
In this article, we develop a non-randomized multi-category response model for a single sensitive survey question with multiple outcomes. Unlike existing randomized response models, our proposed model does not require any randomizing device and the respondents are merely asked to answer a non-sensitive question. It thus reduces cost, ensures reproducibility of respondents' answer (i.e., the same respondent gives the same answer if the survey is re-conducted under the non-randomized multi-category model), enhances respondents' trust on the privacy policy, and motivates respondents' cooperation. We show maximum likelihood estimates (MLEs) of cell probabilities can be obtained in closed- form. Bootstrap standard errors and confidence intervals (CIs) of the cell probabilities or their functions are then given. Bayesian estimation via the data augmentation algorithm is developed when prior information on the parameters of interest is available. Simulation studies are conducted to evaluate the performance of the MLEs and CI estimates. A real data set from a questionnaire on sexual activities in Korean adolescents is used to illustrate the proposed design and analysis methods.
Hepatitis B Virus Gene Mutations and Hepatocarcinogenesis
Liang, Tao,Chen, En-Qiang,Tang, Hong Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.8
Chronic hepatitis B virus (HBV) infection has long been the most common cause of hepatocellular carcinoma (HCC). However, some aspects of the pathogenesis of HBV infection and genesis of hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) are still inconclusive. An increasing number of published studies indicate that hepatitis B virus mutations are associated with risk of HCC. These variations include, in particular, mutations in ORF S,C,X gene regions. This mini-review summarizes results of clinical studies and molecular mechanisms on the possible relations of HBV mutations with the development of hepatocellular carcinoma.