Volume Volume 2 No.2 1992

ABSTRACT: Although prototyping has been widely publicized recently, it has only been adopted by a few organizations. The lack of explicit guidelines for controlling the iterations is one of the principal reasons for its under-utilization. There have been attempts by researchers to overcome this problem but none of them offer any explicit suggestions on how to exercise more control on the prototyping approach. A new controlling scheme known as the User Satisfaction Approach together with a model on how to implement the principles and ideas is presented here. Explicit guidelines are offered for monitoring and controlling the progress of the prototype. This approach greatly improves the controlling mechanism and therefore encourages data-processing managers to adopt prototyping approach in their systems development. AUTHOR: Mohd. Hasan Selamat and Md Mahbubur Rahim KEYWORDS : Prototyping, systems development, user satisfaction, control, management.

ABSTRACT: The kinetics of extraction of a soluble constituent from rose-hip tea has been interpreted by a steady state model. The model is able to derive a quantitative relationship between the concentration of a particular constituent in the bulk solution and the time leading towards the. determination of an overall rate constant for the infusion. The kinetic equation shows the overall rate constant is made up of three contributions which arise from the diffusion of the constituent through the particle, its transfer across the particle/water interface, and its diffusion through the Nernst layer before reaching the bulk solution. The infusion of ascorbic acid and selected mineral ions into water from rose-hip teas thus provide a model for future quantitative kinetic and equilibrium study of solute extraction for other similar materials. AUTHOR: S.S. Chen KEYWORDS: Kinetics, extraction rate, steady state, diffusion, infusion, rose-hip, ascorbic acid, high performance liquid chromatograph, ion chromatograph, mineral elements.

ABSTRACT: Among the Al-, Fe- and Mn-doped lanthanum modified lead zirccinate titanate {PLZT) prepared, only manganese affected the mechanical quality factor Qm of the ceramic. The manganese ions enhances the oxygen vacancies which act as pinning points to the domain wall motion and thus increases the Om value. The high oxygen diffusion coefficient reflects the abundance of oxygen vacancies within the sample. AUTHOR: Aishah Isnin, Josefina Celorico, K. Tsuji, H. Haneda, A. Watanabe and S. Shirasaki KEYWORDS: Lanthanum modified lead zirconate titanate {PLZT) doped, mechanical quality factor, oxygen vacancies, oxygen diffusion coefficient.

ABTRACT: The use of diaphragm electrolysis in the disposal of toxic s!udge was studied with the aim of conserving heavy metal resources and re-utilizing valuable metals recovered from the sludge. This process could eliminate sludge quantity of more than 90 percent by volume, thereby saving on treatment and disposal costs. Benchscale studies were carried out to determine the optimum conditions for good recovery of nickel from factory-segregated nickel sludge. A scale-up on a 110-litre prototype confirmed similar results of 90-100% cathode efficiencies using factory-segregated nickel sludge. The product was tested for its purity. Economic assessment was attempted which showed the viability of the process especially if the treatment and disposal costs were included. This process is applicable for recovery of other heavy metals such as copper and zinc. AUTHOR: T.Y. Chew and G.H. Tee KEYWORDS : Clean technology, diaphragm electrolysis, toxic sludge, electroplating, heavy metal recovery, re-utilization, economic assessment, sludge disposal, sludge treatment, disposal costs.

ABSTRACT: This paper addresses the development of intelligent self-learning controllers using back propagation neural networks for two kinds of temperature control processes: a miniaturized model of an industrial furnace and a water. bath. The method does not require the use of any prior conventional controller or knowledge regarding dynamics which can be easily applied to a wide variety of stable control systems. The neural networks learn the inverse dynamic models from the.open-loop input-output behaviour of the process plants. Once trained, they are configured as direct controllers to the plants similar to a conventional feedback control scheme. A novel feature of the neurocontrollers is that they can be continuously trained on-line by specialized learning, to further improve their performance. Experimental results show that the neuro-controllers compare well with conventional feedback controllers, giving improved performance and robustness, and are easier to implement with no requirement for tuning when confronted with moderate load disturbances. AUTHOR: Marzuki Khalid KEY WORDS : Backpropagation neural networks, intelligent controllers, input-output behaviour, self-learning, inverse dynamic models, real-time control.