Common Sense Reasoning in Diagnostic Systems - Efficient Decision Support Systems: Practice and Challenges from Current to Future - page 108

The case library can be included in the structure of the knowledge base of RT IDSS or act as
a separate component of the system. The structure of case library is represented in Fig. 6.

4. Application of case-based reasoning for diagnostics of complex object
states
As a complex object, we shall view an object which has a complex architecture with various
interrelations, a lot of controllable and operated parameters and small time for acceptance of
operating actions. As a rule, such complex objects as the power unit are subdivided into
technological subsystems and can function in various modes (regular, emergency, etc.).
For the description of such complex object and its subsystems, the set of parameters is used.
The state of object is characterized by a set of concrete values of parameters.
In the operative mode, reading of parameters values from sensors for all objects is made by
the system of controllers with an interval in 4 seconds. For this time interval, it is necessary
to give out to the DMP (operator) the diagnosis and the recommendations on the given
situation.
Diagnosing and detection of operating actions is carried out on the basis of expert
knowledge, technological requirements and operative instructions. The developed software
(Case Libraries Constructor - CLC) can be applied to the decision of the specified problems.
Basic components of CLC are:
 a module for storage and loading the cases to library and for data import;
 a subsystem of visualization for browsing the structure of a case library;
 a subsystem of editing and adjustment of a case library;
 a module of new case check;
 a subsystem of case library testing and case-based reasoning.
CLC was implemented in Borland C++ Builder 6.0 for Windows 7/ NT/XP.
This tool was applied in the prototype of a RT IDSS for monitoring and control of complex
objects like power units on the example of a pressurizer in pressurized water reactor (PWR)
of the atomic power station (Fig. 7) [Eremeev et al., 2007b, 2008].
Implementation of the case library with using CLC for expert diagnostics systems is
subdivided into the following main stages:
 Creation of case libraries for subsystems of complex object;

 Adjustment of the created case libraries;

 Addition of cases in case libraries;

 Check of the added cases;

 Testing of the filled case libraries with using case-based reasoning;

 Reservation of the created case libraries for their subsequent transfer to operative

maintenance.

5. Model-based diagnostics

Many diagnostics problems require building the behaviour prognoses, the work with
contradictions and defaults, effective treatment of new facts and assumptions. The typical
problem of diagnostics is to find a faults of a diagnosed device on the basis of some set of
observations.
The generalized problem of diagnostic can be formulated as follows. There is a device
exhibiting an incorrect behaviour. The device consists of components, one or several of