William Scott

Requirements for a Metamodel to Facilitate Knowledge Sharing between Project Stakeholders

The successful realization of the goal of Model-Based Systems Engineering (MBSE) practice, to contain all project information in models, is predicated on the ability of the system model to represent the information needs of a broad range of stakeholders such as the owners, acquirers, suppliers, maintainers, and users. The paper opens by discussing the interface between the acquirer and supplier within the pre-contract competitive Australian defence context. From this and earlier work, the need for the model of the system of interest to be built upon a comprehensive knowledge representation that can support the creation and integration of multiple stakeholder specific models is derived. Elicitation of further requirements from both stakeholder workshops and from functional analysis follows.

Stability of the Monofixation Syndrome

Eighty patients with congenital esotropia were followed after surgical alignment within 8 prism diopters of orthophoria. The patients were divided into two groups: 38 with the monofixation syndrome (the M.S. group) and 42 without monofixation (the NO M.S. group). After 17.5 years 74% of patients in the M.S. group maintained alignment within 8 prism diopters of orthophoria. In the NO M.S. group only 45% were similarly aligned after 14 years. The mean time to loss of stability was significantly shorter for the NO M.S.group (pi0.005). We conclude that the monofixation syndrome is not a permanent state although stability of ocular alignment is better if monofixation is present rather than absent.