In a method for determining reliability characteristics for a technical installation, a single FMEA table covering all configurations is initially produced for the whole installation. In its lines, i.e. the description of faults and their consequences, the table also has the rate constants, test periods, repair times and consequences of failure, which are dependent on the configuration of the installation. The table explicitly records how the configuration-dependent entries depend on the respective configuration of the installation. In a further step, configuration-specific FMEA tables geared to a specific configuration of the installation can be extracted from this table. Using the configuration-specific FMEA tables, after conversion into Markov models, reliability characteristics can be calculated for the installation in the particular configuration. (FIG. 1)

A method and a responsive system for signal processing, particularly a system of the safety instrumentation and control of a nuclear power plant. A first database stores the association of the data processing units, data transmission units, and computer programs of the system, as well as a sequence of steps in the automatic signal processing in accordance with an integral processing specification. A second database stores in memory operating parameters and at least one reliability parameter of each data processing unit and each data transmission unit. The contents of the databases are utilized in a reliability module, which determines the reliability characteristic of the responsive system from the data of the first database and the second database. If and when the reliability parameters change, a transmission takes place to the reliability module, so that in each case an updated reliability parameter may be determined. As a result, the currently valid availability of the responsive system can be learned at any point in time, taking into account the high degree of detailing of the system.

A technique is provided for the association of constraints with data object classes in an object-oriented database. Given a constraint comprising zero or more quantifiers followed by a quantifier-free boolean expression, a non-primitive reference expression is identified in the boolean expression. The constraint is then modified as follows. First, the primitive reference expression at the head of the identified non-primitive reference expression is replaced with a variable. Then a universal quantifier which quantifies the added variable over all data objects in the class comprising that primitive reference expression is added to the constraint. Finally, a disjunctive condition specifying that the added variable is not equal to the primitive reference expression is added to the boolean expression. The modified constraint may then be associated with the class comprising the aforesaid primitive reference expression. This modification may be performed repeatedly, for each of a number of non-primitive reference expressions. The boolean expression may comprise one or more function calls with implicit non-primitive references which may be identified. The modified constraint may then also be associated with classes based on these references. The modified constraint may be evaluated whenever an object in an associated class is updated. A modified constraint which has been associated with a given class may be further modified to improve evaluation efficiency.

A knowledge base generating system includes a knowledge base having a first knowledge base containing sets of causal relation knowledge describing cause-effect relations of events taking place within a target machine, and having a second knowledge base containing sets of membership knowledge describing a structure of members of the target machine, each event of the cause-effect relations having data to identify one of the members, so that the first and second knowledge bases have mutually retrievable data, a retrieval part for retrieving a number of first members in the second knowledge base, which members correspond to similar causal relation knowledge sets within the first knowledge base, a detection part for detecting whether or not there is a high-rank member in the second knowledge base, the high-rank member corresponding to each of the first members on the basis of the membership knowledge of the second knowledge base, and a commonizing part for generating a common causal relation knowledge set, corresponding to the high-rank member, in the first knowledge base, when the high-rank member is detected.

A method for quantitative estimation of the reliability of a technical system for complex systems with a multiplicity of components. First, second and third failure rates are distinguished for the system components. An upper, lower and, if appropriate, mean value are in each case estimated for the largely unknown second failure rates by subjective expert opinion, and all upper, lower and, if appropriate, a mean probability distribution and, if appropriate, a mean probability distribution of the system reliability. Systematic correlations between expert estimates are thereby taken into account. For the first failure rates, mean values obtained from operational experience are determined with a confidence interval, and widened Poisson distributions are calculated. Furthermore, it is possible to add to the overall probability of the system reliability the Poisson distribution of third types of fault whose failure rates are known a priori or with a high statistical reliability.