Graeme Cole

This document summarizes the supervisory control and data acquisition (SCADA) system that allows communication with, and controlling the output of, various I/O devices in the renewable energy systems and components test facility RESLab. This SCADA system differs from traditional SCADA systems in that it supports a continuously changing operating environment depending on the test to be performed. The SCADA System is based on the concept of having one Master I/O Server and multiple client computer systems. This paper describes the main features and advantages of this dynamic SCADA system, the connections of various field devices to the master I/O server, the device servers, and numerous software features used in the system. The system is based on the graphical programming language "LabVIEW" and its "Datalogging and Supervisory Control" (DSC) module. The DSC module supports a real-time database called the "tag engine," which performs the I/O operations with all field devices attached to the master I/O server and communications with the other tag engines running on the client computers connected via a local area network. Generic and detailed communication block diagrams illustrating the hierarchical structure of this SCADA system are presented. The flow diagram outlining a complete test performed using this system in one of its standard configurations is described.

Jawa is a Java tool-kit for distributed applications development. It provides an infrastructure for automatic management of remote computers, and a framework for mobile objects applications development. The scheduling and migration of mobile objects to remote computers utilizes the parallelism and scheduling principles; in which a Jawa based application may expect performance improvements. More over, Jawa also simplifies the development cycle of its respective application.

One of the primary advantages of the internet is its ability to enable flexible, 24-h access to up-to-date information, irrespective of the geographic location of the user. It is thus rapidly becoming an important tool for the dissemination of information on a global scale. In order to take advantage of the increased accessibility available through the internet, the Murdoch University Energy Research Institute has developed an internet-based version of its physical renewable energy remote area power supply (RAPS) demonstration system. In this way, the physical site, which aims to inform the community about the cost, performance and reliability of renewable energy systems by enabling them to visit a practical operating RAPS system, is available to a much larger audience. The internet-based site, WebRAPS, contains a number of features including case studies of the three RAPS systems at the physical site, specifications of the components used in the systems and general information about the renewable energy system technologies. It also displays historical and real-time data from a monitoring system integrated with the largest of the physical RAPS systems. Visitors to the internet site are able to see how the RAPS system is operating, almost as well as if they were present at the physical site itself. This paper demonstrates the features of the WebRAPS site and discusses how it was developed. Murdoch University Energy Research Institute, Australia, developed an Internet-based version of its physical renewable energy remote area power supply (RAPS) demonstration system. Information on the cost, performance, and reliability of such systems is available to a much larger audience as users and community stakeholders can visit a practical operating RAPS system. Case studies are presented for each of the three systems in the RAPS building, including a 24 V system with 300 W solar array and 300 W wind turbine, a 48 V system with 1.2 kW solar array and 1.8 kW wind turbine, and a 12 V caravan system with 160 W solar array. (from World Renewable Energy Conf Proceedings, Perth, Australia, Feb 99).

Detection thresholds were obtained for a circularly-symmetric Gabor profile and Craik-Cornsweet profiles presented on a large white adapting field. These stimuli possessed peak spatial power between 1 and 6 c/deg. Their contrast was represented in an L, M and S cone contrast space. Detection thresholds were obtained for many vectors close to specific but theoretically important planes within this space. These data were fitted with a model comprising independent mechanisms, each a weighted sum of cone contrasts. The fit revealed a chromatic mechanism driven by ΔL/L - ΔM/M with no S cone input. Within cone contrast space, this mechanism was more sensitive than both a luminance mechanism with little S cone input but considerable variation in relative L to M cone input, and a blue-yellow chromatic mechanism.