Ihsan Faraj

Knowledge-based learning environments for construction

Abstract Developments in information technology have revolutionised the delivery of online learning to such an extent that interoperability, scalability, adaptability and mass-customisation are now becoming practical solutions for pan global delivery. However, whilst advocates of virtual learning environments, and advanced learning management systems often extol the virtues of e-learning per se, they often fail to articulate the limitations of such systems, especially concerning the ‘personalisation’ of the learning process and incompatibility with pedagogic needs. This paper presents an analysis of previous research in the field of knowledge based learning environments using the context of construction as an exemplar. A conceptual framework for developing a fully-customisable knowledge-based learning environment is proposed which uses knowledge objects linked to an object oriented database, the concept of which embraces interoperability, intelligent tutoring, shareability (learning content), and an intelligent interface to manage advanced learning object metadata.

Manufacturing features: verification interaction accessibility and machinability

A major problem in CAD/CAM integration lies in the difficulty in representing the component definition adequately for all applications. Features are considered as a main factor in the CAD and CAM link because various design, engineering and manufacturing data can be associated with a feature. However, tagging feature labels onto geometry does not guarantee the geometric correctness of the resultant feature; knowledge of the topology and analysis of the geometry is needed to correctly identify the validity of the resultant feature. This paper discusses a feature-based design system capable of representing 2.5D components in terms of manufacturing features such as holes, slots and pockets, which are associated with distinctive manufacturing processes. The system is capable of verifying all the defined features by comparing the definition of the resultant features against those of the applied features. Feature interactions are considered to investigate the effect of the interaction on the validity, accessibility and machinability of each feature. Individual features can be extracted from the product model, where all the information about the product is held, for analyses. Each volumetric feature corresponds to a solid that can be removed by one or more machining operations; as a consequence of applying volumetric features, surface features are generated. These surface features provide enough information to enable the validity and machinability of the individual features to be determined and to establish the possible routes in which the feature can be accessed, if any. The proposed approach has been explored in a rapid prototyping test bed consisting of product modelling environment coupled with a solid modeller.

Global project collaboration in the construction industry: standardisation and integration

Collaborative working in construction is becoming widely spread as many activities are performed globally with actors based in various geographical locations. A number of technologies have evolved over the last few years that make it possible to explore new architectures for computer integrated environments. This paper discusses the underlying standard data models (IFC) and their implementation in an integrated database. The database has evolved to be a central repository to a number of distributed construction applications. CORBA is used to enable data to be transparently shared through an integrated computer environment. This environment is based on a three-tier architecture, where user interfaces, business logic and database are kept separate. It supports design (CAD), visualisation (VR and Drawing Web Format – DWF, data sheet), estimating, planning, specifications and supplier information. The environment also enables project information to be exchanged through a STEP Part-21 file and shared through the IFC database. A set of web pages allows for remote interaction, as well as access to the distribution of applications. This provides great flexibility and portability, thereby enabling construction professionals to contribute as well as to perform and manage their own activities.

Verification and spatial clearance of features in a product modelling environment

In features based design systems that are underpinned by solid models, buildings are designed by applying features to the design domain. A feature may be translated and/or rotated in order to position it in the desired place. Contradiction between the applied features and resulting features may occur due to the features interaction, wrong positioning, or inadequate parameters supplied by the user during the product definition. Moreover, the application of other features may cause some features to degenerate to further features. Therefore, verification of the resulting features must be performed against the applied features to establish whether the resulting features conform to the underlying geometry. Current feature‐based design systems employ a mechanism of tagging feature labels onto geometry. This approach does not guarantee the geometric correctness of the resultant feature and knowledge of the topology of the resulting feature and a geometric analysis is necessary to correctly identify the validity of the resultant feature. The research reported in this paper proposes an alternative approach which uses a product model that permits all geometrical and technological information associated with the design and construction stages to be represented. Individual features can be extracted from the product model and analysed to determine their accessibility. Methods which use the product description and other construction data to determine feature validity, accessibility and machinability are used. Each volumetric feature corresponds to a solid that can be added by one or more construction process or removed by one or more machining operations; as a consequence of applying volumetric features, surface features are generated. These surface features provide enough information to enable the accessibility, and machinability of the individual features to be determined and establish the possible routes in which the feature can be accessed if any.

Geometric verification of design

This paper discusses an approach for constructing product models in terms of features. In particular, the work focused on features verification and their accessibility using the solid model representation of the design. The research was motivated by the inadequacy of the current geometric modellers to perform verification and accessibility analyses, resulting in possible contradictions between the intended and the resultant features. Consequently, the wrong data are passed to the applications that use the data. The paper describes an alternative approach that considers the geometry, topology of the design and other construction and engineering information of the product rather than the simplistic approach, which is implemented in many geometric modellers; and is based on tagging feature labels on geometry. Individual features are extracted from the product model, where all the information about the product is held, for analyses. Each volumetric feature corresponds to a solid. As a consequence of applying volumetric features to the design model, surface features are generated. These surface features provide enough information to enable the validity and accessibility of the individual features to be determined and establish the possible routes in which the feature can be accessed, if any. The algorithms that are used to determine the validity and accessibility of features will be discussed.