Browsing by Author "YANG, Shaofa"

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    The Discrete Time Behaviour of Restricted Linear Hybrid Automata
    (2008-12-15T01:59:32Z) AGRAWAL, Manindra; STEPHAN, Frank; THIAGARAJAN, P. S.; YANG, Shaofa
    We summarize results from [2, 3, 1] on the discrete time behaviour of a class of restricted linear hybrid automata. Specifically, we show the regularity of the discrete time behaviour of hybrid automata in which the rates of continuous vari- ables are governed by linear operators in a diagonal form and in which the values of the continuous variables can be observed only with finite precision. Crucially, we do not demand—as is usually done—that the values of the continuous vari- ables be reset during mode changes. We can cope with polynomial guards and we can tolerate bounded delays both in sampling the values of the continuous variables and in effecting changes in their rates required by mode switchings. We also show that if the rates are governed by diagonalizable linear operators with rational eigenvalues and there is no delay in effecting rate changes, the discrete time behaviour of the hybrid automaton is recursive. However, the control state reachability problem in this setting is undecidable.
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    Improved Algorithms for Low Power Multiplexor Decomposition
    (2006-05-17T09:04:24Z) YANG, Shaofa; LEONG, Hon Wai
    It has been estimated that multiplexors (MUXes) make up a major portion of the circuitry in a typical chip. Therefore, to reduce power consumption of a chip, it is important to consider the design of MUXes that consumes less power. This is called the low power MUX decomposition problem and has been studied in [NLCL97]. This paper improves on the results of [NLCL97] in two ways: (a) we propose a method to speed up the algorithms in [NLCL97], and (b) we propose a post-optimization procedure to further reduce the overall power dissipation of decompositions obtained by any MUX decomposition algorithm. Using this post-optimization procedure, we have been able to further reduce the power dissipation results of [NLCL97]. [NLCL97] U. Narayanan, H.W. Leong, K.-S. Chung, and C.L. Liu, ``Low power multiplexer decomposition", in Proc. of Int. Symp. on Low Power Electronics and Design 1997, pp. 269--274, IEEE Press, 1997.