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Interactive Case Memories as Knowledge Mediators between Strategic Planners and Technical Simulation Systems in the Electricity Supply Industry


1. Abstract

This proposal is to investigate the use of Case Based Reasoning (CBR) [Kolodner, 93] in the form of Interactive Case Memories (ICMs) [Dearden, 95] as a mediating technology for communicating knowledge between two domains of expertise, each of which offers a  distinct perspective on common subject matter. We hope to uncover principles governing the use of CBR in this mediating capacity, and to improve our understanding of the issues arising when embedding case-based assistance to support the users of complex systems.
As a case study, we aim to collaborate with EA Technology Ltd., via ERCOS funding, in developing and evaluating an ICM to mediate between a suite of tools that support the construction of simulations of electricity supply networks based on detailed engineering knowledge, and strategic planners working within the industry.

Strategic planners in the industry are concerned with the same artefacts as power systems engineers, but their expertise may typically  relate more to financial planning and customer service issues and may not include detailed knowledge of power systems. The ICM will be used to provide access to, and interpretation of, the technical knowledge about the engineering and mathematical modelling of electricity supply networks needed to permit the strategic planners to construct and interpret detailed simulations. The results of such simulations would be valuable in strategic planning because of the need to evaluate the consequences of different investment and maintenance policies.

This application of ICMs will extend knowledge of the use of case based reasoning technology within user-interfaces to complex tools; will contrast with previous work on interactive knowledge based systems which typically assume that the user is either a novice in the domain, or an expert in the same domain as the knowledge within the system; and will evaluate a new approach to supporting the users of simulation tools.

2. Background

In most applications of interactive knowledge based systems, the user is assumed either to be a knowledge worker within the same domain of expertise as the system, as in medical and legal expert systems[Keravnou & Washbrook, 89], or to be a novice, as in the case of simple fault diagnosis systems. In contrast, in this project we propose to investigate an application of an ICM to act as a mediator between two knowledge domains that have only a limited overlap. The two knowledge domains we intend to study are the technical simulation of power systems, and the strategic planning of electricity supply services. These two domains share common units of discourse, but offer substantially different perspectives. Constructing and interpreting simulations of technical systems is typically time consuming and expensive. It may require detailed knowledge of: the simulation language; the domain to be modelled; the mathematical modelling techniques employed; and an understanding of the issues of validation and qualification of the simulation results [Murray-Smith, 94]. As a result of this complexity, strategic planners in technical domains are often unable to benefit from the understanding and information that simulation might provide [Kiviat, 91]. EA Technology are currently developing a suite of tools that is intended to support simulations of power systems based on detailed electrical engineering knowledge. We hope to collaborate with EA Technology by investigating ways in which an ICM can act as a mediator delivering the knowledge required to develop and interpret such simulations to strategic planners in the electricity supply industry.

One proposal that has been made to simplify simulation is the development of domain specific simulation facilities that provide the user with simple building blocks that correspond to significant concepts in a domain. This approach is intended to permit the construction of coarse grained simulations without requiring detailed knowledge of the simulation language. Agentsheets  [Repenning, 93] is an interface development environment in which domain specific simulation facilities can be simply constructed. However, coarse grained, low-fidelity simulations alone are insufficient to support critical business planning decisions. To support such decision making, strategic planners will require support in moving from coarse grained simulations within a domain specific environment, to the editing and interpretation of hi-fidelity simulations that make use of additional technical knowledge.

We propose to exploit work on CBR and ICMs in order to provide the necessary support. ICMs may be an appropriate technology for a number of reasons:
Firstly, the construction of meaningful and informative simulations requires consideration of a large space of possible configurations of the various elements (lines, transformers, customers etc.) of the power system. Also, for each element of the system to be simulated, a range of parameters must be considered, and the way in which the proposed strategy will alter them must be described. ICMs have been suggested as an appropriate method for supporting users investigating large search spaces [Dearden, 95]. Also the construction of technical descriptions of network components is likely to be easier for strategic planners to perform using a strategy of retrieve and adapt than by attempting to construct the description from first principles. Some preliminary work on embedding a design catalogue within a design environment has been conducted at Colorado [Nakakoji, 93].
Secondly, an ICM can be characterised as an extensional representation of a relation between sentences in two languages, a language of problems and a language of solutions [Dearden, 95; Jankte, 93]. The problem of knowledge mediation can similarly be considered as explicating the relation between two languages of discourse. The extensional (i.e. case-based) representation of such a relation has the advantage over intensional representations, such as might be provided by a rule-based system, of being better suited to problems where the domain knowledge is incomplete [Dearden & Bridge, 93; Chi & Kiang, 93].
Thirdly, we hypothesise that many of the components and parameter evolution projections that will be required within simulations to evaluate a particular policy, will share important similarities with elements from prior simulations. By using an ICM to organise information from previous simulations, we hope to exploit this repetition by providing access to precedent cases. Likewise, in interpreting the output of simulations, the results of previous simulations may  be informative. This may be particularly important where a previous similar simulation indicates a potential risk of undesirable consequences.
Finally, the system will need to communicate a very diverse body of knowledge to the user. The use of precedents and cases may provide a natural encapsulation of this knowledge for pedagogic purposes.
We believe that the results that we obtain will generalise not only to other technical domains where simulation would be a valuable technique for strategic planning, but also to other problems involving the  transfer of expertise between knowledge workers in different domains. For example, supporting the users of typesetting systems who have expertise in document authoring, or supporting users in managing the complex system software that is now supported on personal computers.

3. Scientific / Technological Relevance

The simulation community recognises the need to provide improved support for non-expert users of simulation facilities [Kiviat, 91;  Schmidt & Gomes,92; Murray-Smith,94]. CBR, and in particular ICM technology, is increasingly popular  for stand alone advisory systems. ICMs have been applied to help desks[Dearden & Bridge, 93], technical fault diagnosis[Richter & Wess, 91], design assistance [Domeshek et al., 94], and tutoring[Hirashima et al., 93]. However, to date, only a small amount of work has been conducted on the specific issues that arise for human interaction with CBR systems [Dearden, 95]. In particular, we are not aware of any previous work that seeks to apply CBR systems as knowledge mediating tools.
CBR has been used in the context of simulation by Wendel [94]. However, Wendel's system used only a loose coupling between the interactive simulation environment and the CBR system, and the intended users were experts within the same domain as the knowledge represented within the simulator.
Our proposal aims to extend knowledge about the application of CBR and ICM technology as knowledge mediators, and to develop new ways of supporting the users of simulation tools.

4. Relevance to Beneficiaries

The chief beneficiaries of this project will include (not necessarily in priority order):
the information technology industry, which will benefit from the investigation of new ways of supporting users of complex computer systems;
the energy industry, and other network service industries which will benefit from a better understanding of the relationships between strategic planning and technical simulation of networks;
researchers interested in improving the user interface to simulation facilities;
other researchers investigating the use of  case based techniques for tutoring and educational applications.
In particular we plan to collaborate with EA Technology Ltd. through  ERCOS funding. EA Technology hope to exploit our results in developing user support for a simulation facility for electricity distribution companies and other network utilities.

5. Dissemination and Exploitation

It is hoped that the results of this work will be directly utilised  through technology transfer to our industrial partners (EA Technology Ltd. and Regional Electricity Companies).
Additionally, results will be disseminated by means of publications at national and international conferences. In particular through the UK, European and International Case Based Reasoning Workshops and decision support journals; through UK and international HCI / CHI conferences and HCI journals; through ACM SIGSIM and IEEE TCSIM conferences and simulation publications; and through electrical engineering journals, UK workshops organised by the IEE and international conferences on electricity distribution such as CIRED.

6. The Programme


The objective of this proposal is to develop and evaluate an ICM to act as a mediator between two domains of expertise both of which  include very specific and advanced technical knowledge and skills, but where the intersection between the knowledge and skills of the two domains is relatively small.
We have a particular application in mind as a case study in order to investigate this general problem.. We propose to construct and evaluate a prototype ICM to support strategic planners in the electricity supply industry interacting with a suite of simulation tools based on technical engineering models. The ICM will provide knowledge mediation so that strategic planners can use the simulation facilities offered in exploring the consequences of their decisions.
The existence of the  simulation facility for a real world application will permit empirical investigation of the effectiveness of ICMs as knowledge mediators.


The project goals are listed below.
To develop a pair of knowledge models to record key elements of domain knowledge used by engineers in simulating electricity supply networks, and by strategic planners in evaluating the performance of  such systems in commercial and economic terms, which may include safety and environmental factors.
To design and construct a domain specific interface for use in constructing low-fidelity simulations of electricity distribution systems organised around the knowledge models used by strategic planners. The success of this work should be judged by the degree to which users with some basic knowledge of power systems, and particularly strategic planners from the industry, can construct  simple simulations. The simulations produced at this point are not intended to be high fidelity simulations; rather, the purpose is to demonstrate the practicality of designing a user interface to permit simple simulations to be constructed in this domain.
To construct an ICM to support users in developing high fidelity simulations within the framework provided by the domain specific interface. The ICM will assist users in searching a store of previous simulations and components used in previous simulations, and adjusting the descriptions of these components, in order to develop new simulations. The success of this work should be judged by the ease with which the intended users, i.e. strategic planners from regional electricity companies, can construct and edit simulations to investigate a given problem, by using the ICM to search for previously used components and parameter settings.
To extend the ICM to assist users in interpreting the technical results of simulations in terms of their implications for customer service, and to assist in evaluating the quality and reliability of the knowledge provided by their simulations. The success of this work package should be judged by evaluating the appropriateness of the knowledge fragments delivered to the user investigating the outputs of the simulation. This evaluation will require the co-operation of strategic planners to make use of the system, and simulation experts from within EA Technology Ltd. to evaluate the suitability of the knowledge fragments delivered.
To investigate generic design principles that govern the delivery of on-line assistance using CBR techniques. This work will be the most difficult to assess since it represents the abstraction of the key design lessons from the project. The best assessment that would be possible would be the testing  of these techniques by application in a new domain. However, that would be beyond the scope of the current project proposal.


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Andrew M. Dearden, 1995. The use of formal models in the design of interactive case memories. DPhil thesis, Department of Computer Science, University of York
Andrew M. Dearden & Derek G. Bridge, 1993. Choosing a Knowledge Based System to Support a Help Desk. Knowledge Engineering Review, 8(3), pp201 - 222.
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A. Repenning, 1993. Agentsheets: A tool for building domain oriented dynamic visual environments. PhD thesis, Department of Computer Science, University of Colorado at Boulder.
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Oliver Wendel, 1994. Case Based Reasoning in a Simulation Environment for Biological Neural Networks, in Topics in Case Based  Reasoning, Selected Papers from the First European Workshop on Case-Based Reasoning - EWCBR-93, Stefan Wess and Klause Dieter Althoff and Michael. M. Richter (Eds.), pp424 - 435, LNCS 837, Springer Verlag.