Browsing by Author "Liu, MH"

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Cellular neural networks: Mosaic patterns, bifurcation and complexity
(2006-01-01)
Juang, J
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Li, CL
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Liu, MH
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應用數學系
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Department of Applied Mathematics
We study a one-dimensional Cellular Neural Network with an output function which is nonflat at infinity. Spatial chaotic regions are completely characterized. Moreover, each of their exact corresponding entropy is obtained via the method of transition matrices. We also study the bifurcation phenomenon of mosaic patterns with bifurcation parameters z and beta. Here z is a source (or bias) term and beta is the interaction weight between the neighboring cells. In particular, we find that by in.jecting the source term, i.e. z not equal 0,a lot of new chaotic patterns emerge with a smaller interaction weight beta. However, as beta increases to a certain range, most of previously observed chaotic patterus disappear, while other new chaotic patterns emerge.
Effect of mechanical properties using different filler metals on wide-clearance activated-diffusion-brazed Ni-based superalloy
(2000-12-01)
Su, CY
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Chou, CP
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Chang, WJ
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Liu, MH
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機械工程學系
The investigation of mechanical properties and failure mechanism of activated-diffusion-brazed (ADB) joints in IN-738 plate were conducted. Joints of this type, which had wide clearance, were formed using the brazing alloys Nicrobraz 150 and DF4B, The microstructural characterization showed that chromium borides with a blocky morphology were present in joints associated with the two brazing alloys. A major difference in matrix phase chemistry was observed, however, for the two brazing alloys, e.g., an Ni-B eutectic phase was observed in Nicrobraz 150, but DF4B exhibited a coarsened gamma prime (gamma) phase and an absence of a nickel boride matrix phase, Results of tensile test showed that ADB specimens using DF4B brazing alloy exhibited 95% nominal tensile strength of IN-738 base materials. Fracture cracks in the joint area mere initiated and confined to dispersed chromium boride sites. However, tensile test of ADB specimens using Nicrobraz 150 showed poor tensile properties at all testing temperatures, and their fractures were initiated at a brittle nickel boride site and propagated along the weak-bonded interface between the Ni-B eutectic phase and base materials.