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Transfer matrix for rotor coupler with parallel misalignmen
Chao-Yang Tsai,Shyh-Chin Huang 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.5
A transfer matrix for shafts coupler with parallel misalignment (offset) was derived. The responses of a rotor system composed of flexible shafts, unbalanced disks, elastic supports and shafts coupler with misalignment were then investigated. Through the derivation, the boundary shears induced by a rotating shaft were first discovered to be coupled in two perpendicular directions. These coupling shears might reduce the first critical speed up to 50% in the free-free case. The studies showed that the shafts coupler altered the rotor’s critical speeds and the misalignment played as an external load resulting through the whole driven shaft. The combined effects of disk unbalance and shaft misalignment showed that the misalignment predominated the response in most of the rotation speeds, but the unbalance could become significant at high speed. The whirling orbits before and after the misalignment were illustrated as well, and numerical results showed that the two ends of the misalignment whirled asynchronously as the rotation fell into some regions.
What Drives China’s 2015 Stock Market Surges and Turmoil?
Jui-Jung Tsai,Yang-Chao Wang,Xiongwei Li 한국증권학회 2019 Asia-Pacific Journal of Financial Studies Vol.48 No.3
Using high-frequency data, we investigate China’s stock market surges and turmoil from 2014 to 2015 by employing GARCH family models to evaluate the effects of government policies, economic factors, and related announcements. The results indicate that China’s stock market has primarily been driven by government policies rather than economic factors. During the period, the commentaries of the People’s Daily further amplified the direction of market movements in the market surges and turmoil. In addition to individual policies and announcements, we explore the structural changes in volatility in different market stages and provide explanations for the distinct features of each stage.
Tzu-Chau Chen,Chao-Tsai Huang,Yan-Chen Chiu,Wei-Da Wang,Cheng-Li Hsu,Chen-Yang Lin,Lung-Wen Kao 한국정밀공학회 2013 International Journal of Precision Engineering and Vol. No.
Runner system plays a very important role in injection molding process. A quality runner design is helpful in improving product qualities and saving material. However, traditional cold runner systems have certain inherent issues. Moreover, poor product cosmetics are commonly seen with the use of traditional cold runners. As a result, hot runner technology has been widely applied. On the other hand, It has been one of the green molding solutions for material/energy saving and clean environments. But the mechanism behind the hot runner system is too complicated to be fully understood. There exist some critical issues currently. As a result, the simulation technolgy is highly needed to examine hot runner designs before the real manufacturing. Through simulation analyses, designers and manufafctuers are able to catch the potential issues on their hot runner systems and revise their designs. Hot runner simulation technology helps with the investigations into the behavior in hot runner system. In this paper, a true 3D numerical method is proposed and applied to investigate the temperature behavior in a real hot runner system for PC material. The experiment is conducted and the simulating result is compared with that from the experiment for the validation purpose.
Parametric study on a collocated PZT beam vibration absorber and power harvester
Shyh-Chin Huang,Chao-Yang Tsai,Hsiao-Hui Liao 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.11
The parametric effects of a PZT beam that is simultaneously used as a vibration absorber and a power harvester were investigated in this study. A cantilever beam paved with PZT layers and with added tip mass has been widely used as a harvester or sometimes as a Dynamic vibration absorber (DVA). However, the beam is rarely considered a collocated device. In this study, the first step was theoretical derivation of a distributed beam covered with bimorph PZT layers. Then, the beam was attached to a 1DOF vibratory main system. Two indicators for vibration absorption and power harvesting were defined. Numerical results demonstrated that the lumped mass ratio favored both of the abilities, but that the DVA mass ratio influenced these two abilities in exactly the opposite way. The conjunction of a harvester circuit into a DVA shifted its resonance frequency up to 5 % (an extreme case of open circuit R→∞). Simultaneous power harvesting diminished the absorption capability up to 35 % for each set of mass ratios. To achieve the maximum degree of power harvesting, a corresponding load resistance that somewhat increases with the lumped mass ratio is applied. Experimental results verified the existence of the best load resistance, but the measured harvested curve was lower than the theoretical calculation because of structure damping and deviations of PZT material properties.