An hierarchical approach to performance evaluation of expert systems

The number and size of expert systems is growing rapidly. Formal evaluation of these systems - which is not performed for many systems - increases the acceptability by the user community and hence their success. Hierarchical evaluation that had been conducted for computer systems is applied for expert system performance evaluation. Expert systems are also evaluated by treating them as software systems (or programs). This paper reports many of the basic concepts and ideas in the Performance Evaluation of Expert Systems Study being conducted at the University of Southwestern Louisiana

Research Review: Application of Expert Systems in the Sciences

Author Institution: Department of Electrical Engineering, The University of AkronStudies from the field of artificial intelligence have given birth to a relatively new but rapidly growing technology known as expert systems. An expert system is a computer program which captures the knowledge of a human expert on a given problem, and uses this knowledge to solve problems in a fashion similar to the expert. The system can assist the expert during problem-solving, or act in the place of the expert in those situations where the expertise is lacking. Expert systems have been developed in such diverse areas as science, engineering, business, and medicine. In these areas, they have increased the quality, efficiency, and competitive leverage of the organizations employing the technology. During the 1980s, scientists and engineers have used this technology to search for oil, diagnose medical problems, and explore space. This paper provides an overview of this technology, highlights the major characteristics of expert systems, and reviews several systems developed for application in the area of science

A methodology for the interpretation of ground conditions from borehole information.

Geotechnical design requires the interpretation of the information obtained from a site investigation. One aspect of the interpretation is the identification of the ground conditions across the site, based on observations at discrete points, such as boreholes. If a computer system is to assist in this process it must be able to compare soils observed at two or more locations, in order to identify whether the soils observed belong to the same horizon. A methodology has been developed whereby the similarity of two soils can be calculated, based on engineering soil descriptions. The qualitative terms are converted into quantitative representations from which a Similarity Number can be derived. Individual Similarity Numbers can be calculated with respect to soil type, consistency, structure and colour. These are normalised to give values between 0 and 100 (with 100 indicating identical features) and combined using appropriate weighting factors to give an Overall Similarity Number which represents a comparison based on these features. Using die quantitative representation of the soil descriptions, a preliminary assessment of the ground conditions can be made. The correlation of the borehole information is approached at two levels. At the site-wide level, an attempt is made to identify marker beds, that is soil layers which 'stand out' from the general ground conditions. A search for possible marker beds is first made at each borehole. The search is then extended to pairs of boreholes and further, the continuity of marker beds is established inside triangles which are formed having the boreholes as vertices. Where continuous layers are observed within triangles, the dip angle and dip orientation are calculated, to form the geometrical parameters on which preliminary conclusions are based. Compatibility (or not) of these parameters between neighbouring triangles is the key factor for assessing continuity of the marker beds. Finally, the detailed ground conditions are examined on a borehole-to-borehole level. At this level, a set of hypotheses about the ground conditions is constructed by looking at pairs of adjacent boreholes. Hence, a set of hypotheses is produced, even for areas for which the site-wide level approach is unable to establish trends

A SHORT INTRODUCTION TO EXPERT SYSTEMS

Information Systems Working Papers Serie

The place of expert systems in a typology of information systems

This article considers definitions and claims of Expert Systems ( ES) and analyzes them in view of traditional Information systems (IS). It is argued that the valid specifications for ES do not differ fran those for IS. Consequently the theoretical study and the practical development of ES should not be a monodiscipline. Integration of ES development in classical mathematics and computer science opens the door to existing knowledge and experience. Aspects of existing ES are reviewed from this interdisciplinary point of view

A knowledge-based approach to full wave data processing

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1987.Microfiche copy available in Archives and Science.Bibliography: leaves 71-75.by Marc H. Larrère.M.S

A SHORT INTRODUCTION TO EXPERT SYSTEMS

Information Systems Working Papers Serie

ON THE PLAUSIBILITY AND SCOPE OF EXPERT SYSTEMS IN MANAGEMENT

Over the last decade there have been several efforts at building knowledge based "expert systemsâ, mostly in the scientific and medical arenas. Despite the fact that almost all such systems are in their experimental stages, designers are optimistic about their eventual success. In the last few years, there have been many references to the possibility of expert systems in the management literature. However, what is lacking is a clear theoretical perspective on how various management problems differ in nature from problems in other domains, and the implications of these differences for knowledge based decision support systems for management. In this paper, I examine some of these differences, what they suggest in terms of the functionality that a computer based system must have in order to support organizational decision making, and the scope of such a system as a decision aid. The discussion is grounded in the context of a computer based system called PLANET that exhibits some of the desired functionality.Information Systems Working Papers Serie

Knowledge based systems: A preliminary survey of selected issues and techniques

It is only recently that research in Artificial Intelligence (AI) is accomplishing practical results. Most of these results can be attributed to the design and use of expert systems (or Knowledge-Based Systems, KBS) - problem-solving computer programs that can reach a level of performance comparable to that of a human expert in some specialized problem domain. But many computer systems designed to see images, hear sounds, and recognize speech are still in a fairly early stage of development. In this report, a preliminary survey of recent work in the KBS is reported, explaining KBS concepts and issues and techniques used to construct them. Application considerations to construct the KBS and potential KBS research areas are identified. A case study (MYCIN) of a KBS is also provided

The role of mass movements for slope evolution : conceptual approaches and model applications in the Bonn area

Understanding slope processes and slope systems in different timescales is focused by a range of approaches from different disciplines. This work is based on a multi-disciplinary research approach within the project SFB350 `Interactions between and Modelling of Continental Geo-Systems'. Previous work indicate, that mass movements have a considerable spatial and temporal extent in the Bonn area. Moreover, the spatial pattern of these landslides indicate, that they play an important role in the superordinated system of hillslope evolution. The fundamental research objective of this work is the assessement of mass movement processes as part of hillslope systems of the Bonn area. It is queried how the geomorphological effectiveness of mass movements on hillslopes over longer timescales can be quantified, and more general, how slope development, affected by mass movements can be modelled. The methodological approach included (1) local observations and analyses of individual landslide objects, (2) analyses of data from two larger field sites, and (3) aggregation techniques of past climate conditions for the Bonn area. The analyses led to simplified models of lithological boundary conditions for the landslides and for the field sites. Three scenarios of climatic variability for the Bonn area were developed for the last 500 years, based on statistical analyses of proxy data. For each scenario, models of typical annual variation of precipitation and temperature were derived. Modelling approaches on different scales were applied. Slope stability models were used to reconstruct failure conditions for the landslide objects under investigation. A simplified model of hillslope hydrology and slope stability was developed to analyse stability of hillslopes for different climatic conditions. This model was used to calculate failure probability in a scenario approach for three sensitive hillslopes in combination with the identified climatic scenarios. Geomorphometric techniques, including hillslope profile analyses, and a simplified model of hillslope development were applied to model hillslope evolution of one field site (catchment `Melbtal'). A conceptual model for hillslope evolution of the Melbtal was developed on the basis of the results, combining the concept of ergodicity with changing system behaviour. Movement monitoring and and stability analyses indicated the sensitivity of hillslopes in the Bonn area to groundwater fluctuations caused by intensive precipitation phases. These results suggest the application of scenario models to analyse the sensitivity of the hillslopes to changing climatic conditions. The hillslope evolution model indicated five evolutionary stages for hillslope systems of the Melbtal, according to varying material sensitivity, climatic changes, dominant slope processes, and process coupling. Generally, the model results show a transition from a hillslope systems in the upper valley, which is not affected by landslides to a hillslope system in the lower valley, which is dominated by hillslope instabilities and landslides. The change in hillslope processes can be explained by different lithologic boundary conditions. The valley-side slopes affected by landslides were chosen as boundary conditions for the scenario approach (see above) to investigate the sensitivity of the hillslopes to mass movements. The results from scenario modelling led to different failure probabilities for the modelled hillslopes, which could be related to average gradient. The failure probabilities, however, showed a complex pattern in relation to the modelled climatic phases, as indicated by frequency spectra of failure probability. The sensitivity of a hillslope to climatic variation is not correlated with average failure probability, i.e. the hillslope with lowest failure probability showed high sensitivity to changing climate patterns. The scenario models, hillslope profile parameters, and field evidence showed, that the reaction of the hillslope system to changing boundary conditions (material sensitivity) is significantly different for the valley side slopes. Hillslope profile parameters indicate, that a critical system state might be reached by interactions of the hillslope (landslide) system with the fluvial system. The research approach exhibit a series of deficits and error sources. It can be assumed that statistical errors and technical errors are of minor relevance, as the topic of this study is related to relatively large spatio-temporal scales. Certainly, a simplified system of `real' hillslope evolution was modelled. The question arise, if the used model approach is an oversimplification for the complexity of the considered landform system. Studies on similar catchments in the study area could validate the results derived in this study. Validating the results against field data is certainly necessary, but not carried out in this study, because of missing data (e.g. dating results). The applied methods and the results indicated several methodological issues and deliveries within the wider framework of the assessment of hillslope systems. Hillslope profile analysis gave evidence of spatial structures in hillslope systems, which can be transfered in time using the conceptual framework of ergodicity. It could be shown, that combining these results with simplified hillslope evolution models deliver patterns of system behaviour for the process-response system of hillslopes. The scenario model results indicated patterns in process behaviour (in this case landslide processes), which are related to varying boundary conditions and spatial structure of the modelled hillslope. Although no quantification of process rates for varying climatic conditions could be reached, the potentials of this technique for assessing sensitivity of geomorphic processes to controlling factors were shown. Certainly, conceptual approaches and scenario models, require field evidence as input data. With respect to the considered scale, this study used generalised boundary conditions, here termed as `Geo-structures', as field evidence (e.g. climate scenarios). To accomplish this generalisation task, spatial and temporal aggregation techniques are required, which are only partly available today, e.g. by statistical methods and geomorphometric generalisation techniques. Based on the applied methodologies, a general framework for assessing geomorphic systems is sketched. It is proposed to model stages of geomorphic systems, which are described by higher-scale patterns in `Geo-structures' produced by changing process interactions within the related geomorphic evolutionary system (patterns in system behaviour). Different behaviour of individual processes for the systems stages can be simulated by model scenarios