Browsing by Author "Hwang, GH"

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Perpendicular interface resistance in Co/NbxTi1-x multilayers for normal and superconducting NbTi alloy with x=0.4, 0.6
(2005-05-15)
Huang, SY
;
Lee, SF
;
Huang, JC
;
Hwang, GH
;
Yao, YD
We report here the resistance of Co/NbxTi1-x multilayers, for x=0.4 and 0.6, with current flowing perpendicular to the layer plane at 4.2 K. When NbTi films are sandwiched between Co, we found that there are critical thicknesses of 20 nm for x=0.4 and 27 nm for x=0.6, below which no superconducting transition could be found. Using a series resistor model, we extracted the unit area resistance of one pair of Co/NbTi interfaces and compared with the pure Nb case we have reported. The influence of mean free paths and superconducting coherence lengths is analyzed. (c) 2005 American Institute of Physics.
Reachability testing: An approach to testing concurrent software
(1995-12-01)
Hwang, GH
;
Tai, KC
;
Huang, TL
;
資訊工程學系
;
Department of Computer Science
Concurrent programs are more difficult to test than sequential programs because of nondeterministic behavior. An execution of a concurrent program non-deterministically exercises a sequence of synchronization events called a synchronization sequence (or SYN-sequence). Non-deterministic testing of a concurrent program P is to execute P with a given input many times in order to exercise distinct SYN-sequences. In this paper, we present a new testing approach called reachability testing. If every execution of P with input X terminates, reachability testing of P with input X derives and executes all possible SYN-sequences of P with input X. We show how to perform reachability testing of concurrent programs using read and write operations. Also, we present results of empirical studies comparing reachability and non-deterministic testing. Our results indicate that reachability testing has advantages over non-deterministic testing.