Volume 6 (1994)
Table of Contents
Treatment of Metal Finishing Wastewater in Sequencing Batch Process
Metal finishing wastewater contains heavy metals, acids, alkalis, detergents and toxic chemicals such as cyanide far above the Standard B limits of the Environmental Quality (Sewage and Industrial Effluent) Regulation 1979. A sequencing batch process utilising two-tank system was selected to treat such wastewater from a small metal finishing plant in Kuala Lumpur. Treatment with lime and ferrous sulphate complexed and precipitated the cyanide and reduced hexavalent to trivalent chromium which was then precipitated along with other metals as metal hydroxides. The pH of effluent was accordingly adjusted. The pilot plant was designed to run automatically according to a chosen treatment and schedule. The quality of wastewater treated as above was found to meet the Standard B limits.
Pengecilan Gelombang Tekanan dan Kilasan dalam Konkrit (An Attenuation of Pressure and Shear Waves in Concrete)
The use of relative amplitude of ultrasonic waves to evaluate concrete quality is described in this paper. Other than frequency, the scattering of pressure and shear waves is also influenced by inhomogenieties of the propagated media. The attenuation of pressure and shear waves due to scattering differ for certain frequency. Experiments to examine the correlation between concrete compressive strength with relative amplitude of pressure/shear waves and velocity were performed. The results of experiment show that relative amplitude and pressure wave velocity have a good correlation with strength. Finally, a model of combined velocity and relative amplitude is proposed.
Sistem Pemeriksaan Bantuan Penglihatan Mesin (Inspection System of Help Machine Vision)
The development of a machine vision system for inspection of LED devices in industrial environment is discussed in the paper. Methods to detect flaws in LED devices is emphasized. There are two problem statement i.e.: (i) inspect flaws in the LED lead frame at the end of the production line and, (ii) inspect wire loop flaws in the LEDs prior to epoxy encapsulation. Tests were carried out to investigate the capability of the developed machine vision system. Results obtained show a high percentage of success in distinguishing between good and bad LEDs. The generic system described here has a wide application in quality control inspection in the manufacturing environment.
Sliding Mode Fuzzy Controller for the Control of Nonlinear Systems
The aim of the work described in this paper is to develop a suitable controller for positioning a pneumatic cylinder. The dynamics of a pneumatic servosystem is nonlinear because of the compressibility of air. In addition, on-off or binary valves often used in actuating pneumatic cylinders introduces a nonlinear element into the control loop. In this paper, a fuzzy logic controller based on the theory of variable structure systems is proposed. The theory of variable structure has reduced the number of rules required for fuzzy logic control. Experimental results have shown that the controller is able to overcome the nonlinearities and position a pneumatic cylinder accurately.