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1

Avoiding Irreducible CSC Conflicts by Internal Communication

Wist D., Wollowski R., Schaefer M., Vogler W.

Fundamenta Informaticae

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2009

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Vol. 95, nr 1

1-29

EN

Resynthesis of handshake specifications obtained e.g. from BALSA or TANGRAM with speed-independent logic synthesis from STGs is a promising approach. To deal with state-space explosion,we suggested STG decomposition; a problemis that decomposition can lead to irreducible CSC conflicts. Here, we present a new approach to solve such conflicts by introducing internal communication between the components. We give some first, very encouraging results for very large STGs concerning synthesis time and circuit area.

2

Output-Determinacy and Asynchronous Circuit Synthesis

Khomenko V., Schaefer M., Vogler W.

Fundamenta Informaticae

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2008

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Vol. 88, nr 4

541-579

EN

Signal Transition Graphs (STG) are a formalism for the description of asynchronous circuit behaviour. In this paper we propose (and justify) a formal semantics of non-deterministic STGs with dummies and OR-causality. For this, we introduce the concept of output-determinacy, which is a relaxation of determinism, and argue that it is reasonable and useful in the speed-independent context. We apply the developed theory to improve an STG decomposition algorithm used to tackle the state explosion problem during circuit synthesis, and present some experimental data for this improved algorithm and some benchmark examples.

3

Certification of Highly Complex Safety-Related Systems

Reinert D., Schaefer M.

International Journal of Occupational Safety and Ergonomics

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1999

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Vol. 5, No. 4

537--552

EN

The BIA has now 15 years of experience with the certification of complex electronic systems for safety-related applications in the machinery sector. Using the example of machining centres, this presentation will show the systematic procedure for verifying and validating control systems using Application Specific Integrated Circuits (ASICs) and microcomputers for safety functions. One section will describe the control structure of machining centres with control systems using “ integrated safety.” A diverse redundant architecture combined with crossmonitoring and forced dynamisation is explained. In the main section the steps of the systematic certification procedure are explained showing some results of the certification of drilling machines. Specification reviews, design reviews with test case specification, statistical analysis, and walk-throughs are the analytical measures in the testing process. Systematic tests based on the test case specification, Electro Magnetic Interference (EMI) and environmental testing, and site acceptance tests on the machines are the testing measures for validation. A complex software driven system is always undergoing modification. Most of the changes are not safety-relevant but this has to be proven. A systematic procedure for certifying software modifications is presented in the last section of the paper.