M. Zulfikar Ishak

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This paper develops a single order mathematical model for correlating the various electrical discharge machining (EDM) parameters and performance characteristics utilizing relevant experimental data as obtained through experimentation. Besides the effect of the peak ampere, pulse on time and pulse off time on surface roughness has been investigated.(More)
We derive new limits on the value of the cosmological constant, Λ, based on the Einstein bending of light by systems where the lens is a distant galaxy or a cluster of galaxies. We use an amended lens equation in which the contribution of Λ to the Einstein deflection angle is taken into account and use observations of Einstein radii around several lens(More)
This paper presents the numerical study on two-dimensional forced convection heat transfer across three in-line flat tubes confined in a channel under incompressible, steady-state conditions. This system is solved in body-fitted coordinates (BFC) using the finite volume method (FVM). The constant heat flux is imposed on the surface of the tubes as the(More)
Joining dissimilar metals has recently become very popular in industries because of the advantages associated with the weld joint. This paper focuses on an investigation of mechanical and material properties, and the optimization of mechanical properties in resistance spot welding methods in lap configurations between AISI 301 stainless steel and AISI 1020(More)
A new image transmission and teleconference system using international digital telephone services was established between Japan and Malaysia. This new system consists of an ordinary personal computer, image scanner, and terminal adapter for digital telephone lines. The quality of images transferred using this system was high enough for diagnosis and(More)
  • Ghusoon Ridha Mohammed, Mahadzir Ishak, Syarifah N. Aqida, Hassan A. Abdulhadi
  • 2017
The effects of input heat of different welding processes on the microstructure, corrosion, and mechanical characteristics of welded duplex stainless steel (DSS) are reviewed. Austenitic stainless steel (ASS) is welded using low-heat inputs. However, owing to differences in the physical metallurgy between ASS and DSS, low-heat inputs should be avoided for(More)
Torrefaction process of biomass material is essential in converting them into biofuel with improved calorific value and physical strength. However, the production of torrefied biomass is loose, powdery, and nonuniform. One method of upgrading this material to improve their handling and combustion properties is by densification into briquettes of higher(More)
This paper presents the numerical study of two-dimensional forced convection heat transfer for staggered tube banks in cross flow under incompressible, steady-state conditions. This system is solved for body-fitted coordinates using the finite volume method for flow over a bundle of cylindrical tubes. A constant heat flux is imposed on the surface of the(More)
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