Much research has been undertaken towards determining why programming errors occur during systems development and this has resulted in improved techniques for use by practitioners and teachers. However, little research has been done on errors occurring in end-user applications such as spreadsheets that are not developed under formal system development guidelines. The approach taken in the research reported here is that many of these errors are due to an education process that concentrates on teaching 'how to do things correctly' but ignores 'how to avoid doing things incorrectly'.Research into the development of spreadsheets has identified common errors made by end users in industry and by students whilst learning. It has been shown that there is a correspondence between industry and education in the types of errors made. From this has developed an approach which, in addition to teaching correct methods of building systems, implicitly addresses the common errors identified above.

Following a proposal at Loughborough University that “reading lists should be made available online” the university library undertook responsibility to design and develop a system to achieve this aim. Using open source tools the rapid development of a reading list management system soon followed, and by Autumn 2000 the solution had been successfully implemented at the university. The system is now available to other institutions as open source software.

This paper introduces the first stage of a new model-based approach to three-dimensional (3D) human movement tracking. A 'generate-and-test' matching procedure was adopted by matching rendered images of a 3D computer graphics model of the human body to target images of rigid body motion. The set of pixels to be compared were just those corresponding to the model of the body in the rendered images. The matching criterion to optimise model position and orientation was based on the minimisation of the RGB colour difference between generated model images and associated target images. The method was able to track synthetic image sequences of a half twisting somersault accurately with root mean square errors of less than 5 mm and 0.3° for position and orientation estimates respectively. The suitability of the proposed approach for rigid body motion tracking was supported by additional tracking experiments on video image sequences of 'wooden cross' trajectories. Comparisons of tracked estimates against manual digitising estimates returned relatively small rms difference values on both side somersault and twisting somersault movements. The proposed approach has the potential to track video images of a human torso using a rigid body model and hence to track articulated movements by successively adding segments to the model in a hierarchical manner.

This paper describes the implementation and use of a prototype multicast late‐binding RPC (LbRPC) system. The system provides a mechanism for exporting arbitrary code and data across a wide area internetwork to multiple hosts for evaluation. This mechanism provides a means to ensure that the total execution time for the application is as small as possible without requiring continual monitoring and estimation of the state of the hosts and the intervening network. The impact of sending the same code and data to a group of remote hosts is minimized by using multicast Internet protocol (IP) communications for the outward leg of the transaction. This prototype implementation demonstrates the feasibility of using multicasting for process placement and some performance measurements are included to show how it stands up to usage on the Internet. The paper concludes with a discussion of outstanding issues raised by this research.

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