Browsing by Author "Tsai, C. -H."

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DYNAMIC ANALYSIS OF HULA HOOP MOTION AND OPTIMIZED ENERGY HARVEST CIRCUIT
(2014-01-01)
Huang, T. -C.
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Chao, Paul C. -P.
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Chen, W. -D.
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Tsai, C. -H.
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Lu, C. X.
The nonlinear dynamics of hula hoop motion is deciphered in this study by nonlinear dynamic modeling techniques to find solution and stability analysis. This is different from the previous study [1], where a homotopy method is employed. The analysis results are capable of transforming linear reciprocating motion into rotational motion. The dynamic governing equations of the system are first successfully derived by force balance. The non-linear dynamic analysis is next applied to derive approximate, asymptotic solutions. Stabilities associated with all solution are determined by subsequent analysis on the derived asymptotic solutions. In addition, the transformer could be integrated with coils, magnets, and electric circuits to form a portable energy scavenging device. A novel front-end circuit is proposed in this work for harvesting human\'s energy. The situation of human\'s walking and running is simulated by a shaker. And the ac-like energy is processed by the novel energy harvesting circuit, transformed as a DC voltage suitable for devices successfully. The efficiency of the entire circuit is proven up to 60%, and is an input-powered circuit with no standby power. A complete experimental system is also designed and successfully confirm the existence of the stable nonlinear solutions found by analytical and numerical analysis.
Effect of nanomechanical and microstructural properties on annealed multilayer Si0.8Ge0.2-Si films
(2012-04-01)
Lin, T. -Y.
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Tsai, C. -H.
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Yau, W. -H.
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Chou, C. -P.
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機械工程學系
In this study, ultrahigh vacuum chemical vapour deposition was employed to deposit multilayered silicon-germanium (SiGe) films. Subsequently, we take those samples for ex situ thermal treatments in the furnace system (400 and 500 degrees C). The periodic multilayer SiGe with different annealing conditions measured by a commercial nanoindenter observed the slight increase in hardness. The cross-section profile and the microstructure of SiGe multilayer films were characterised by means of atomic force microscopy and transmission electron microscopy. The effect of the thermodynamics of the thin film/substrate system is evidenced by annealing treatment. It is demonstrated that the SiGe multilayer films are more susceptible to plastic deformation while annealing treatments are carried out. The misfit dislocations in the critical pile-up event were observed in the periodical SiGe multilayer that can be relaxed at thermal annealing, thus providing the nanomechanical performance.