This paper presents an approach to the test generation for synchronous sequential circuits. This approach utilizes an extended logic simulation, called 7eal-valued logic simulation, and solves the sequential test generation problem as a kind of optimization problem. The approach has the possibility of high speed test generation, because high speed processing techniques, such as, vector processing, parallel processing, and so on, can be efficiently applied to the most time-consuming part of this approach. Experimental results for ISCAS'89 benchmark sequential circuits also illustrate the eficiency of this approach.
SUMMARYThis paper presents a test generation method using an optimization technique for a single stuck-at fault in synchronous sequential circuits. This method utilizes a new real number simulation for defining the cost of an input pattern for a given fault and leads an input pattern to a test pattern by changing the input repeatedly to minimize its cost.Since a sequential circuit has internal states, a test pattern for a fault is a sequence of input vectors for several time frames. For generating the whole test pattern, the concept of forward test generation, which performs the convergence calculation process at multiple time frames, is introduced to avoid the problem of local optimum.Experimental results for ISCAS '89 benchmark sequential circuits show the effectiveness of the proposed method for sequential circuit test generation.
An AC magnetic suspension system with an LC circuit consisting of an electromagnet and a capacitor has selfstabilization property. Such property is achieved by setting the frequency of the applied voltage to be higher than the resonant frequency of the LC circuit. The AC magnetic suspension system with indirect damping can achieve stable suspension without active control. The previous study indicated that self-stabilization failed due to interferences among the electromagnets in a multiple-degree-of-freedom AC magnetic suspension system. In this paper, the influences of interferences among the electromagnets on floating characteristics are studied experimentally. It is found that the resonant frequencies of LC circuits vary according to the interferences among the electromagnets. It explains why stable suspension could not be achieved. A new apparatus with a larger size and a different structure for reducing the interferences are developed. Stable noncontact suspension is achieved in the apparatus. In addition, the interferences are further reduced by making the resonant frequency of each LC circuits different. It leads to the improvement of floating characteristics.
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