Zulkafli Hassan

Application of orthogonal optimization and feedforward backpropagation model in the microwave extraction of natural antioxidants from tropical white pepper

The tropical white peppercorns are common commodity crops which have been traditionally used for the treatment of many free radical-related diseases. These medicinal properties are due to the presence of natural antioxidants. This study investigated the combination of microwave extraction parameters for the recovery of natural antioxidants from the white pepper matrix. Microwave-assisted technique was used for the extraction of bioactive oleoresin from white pepper. Taguchi experimental design was employed to investigate the combination of independent extraction parameters for optimal recovery of natural antioxidants. The feed backpropagation artificial neural network model was thereafter applied to optimally predict the result for the different combination of operating parameters. This was achieved by evaluating different algorithms, transfer functions, and neurons. The result obtained from the orthogonal parametric study gave an optimal antioxidant activity of 91.02% at irradiation time of 120xa0min, microwave power level of 350xa0W, particle size of 0.300xa0mm, and liquid-to-solid ratio of 6xa0mL/g. The gradient descent (GD) algorithm, tansigmoid transfer function, and 4-x-3 topology were used to model the experimental data. A better prediction was then obtained with an overall coefficient (R) and mean square error (MSE) of 0.9595 and 1.4381, respectively. In this study, the feedforward backpropagation neural network was successfully applied to optimally evaluate the complex relationship between the input extraction parameters and the response.

Novel and Enviromentaly Friendly Mechanical Technique to Improve the Flow in Water Pipelienes

The paper is concerned with an experimental investigation of the drag reduction in turbulent channel flow over the mechanical chain. A circulating loop for the fluid flow with 0.0381 inside diameter of pipe is set up. The testing length of the system is 1.5m.Wall shear stress reduction performance has been investigated experimentally for various design geometry surfaces including a replica of bent consisting of stainless steel model scales. Attempts to optimize the net drag reduction by varying the design geometry and alignment are also discussed. The study indicated that the mechanical chain taken in water flow is capable to decrease the friction drag of a turbulent flow up to 40%. The maximum percentage was achieved in 39.37L/D at RE equal to 56733. The results show that a substantial drag reduction can be achieved by this mechanical chain in aqueous media.

Glycolic Acid Ethoxylate 4-Tert-Butylphenyl Ether as Drag Reducing Agent in Aqueous Media Flow

Glycolic acid ethoxylate 4-tert-butylphenyl ether was used as investigated anionic surfactants in this experimental work. A built up rig with ratio of pipe length to diameter (L/D) is equal to 59 was used to achieve the purpose of this work which is to investigate the drag reduction in turbulent flow with different flow rates and concentration of additive. In the present study, the concentrations (ppm) of additive were analyzed starting from 200, 300, 400, 500 and 600, respectively. The flow rates (Re) of the solution were from 11235, 22470, 33705, 44940, 56175, 67410 and 78645, respectively. It was found that glycolic acid ethoxylate 4-tert-butylphenyl ether is capable to reduce the drag less than 10 %. The highest drag reduction is 8 % was achieved in 600 ppm of solution for turbulent flow with Re within the range 44940 to 56175. The results of experimental work shows that this anionic surfactant perform as a poor drag reducing agent due to its drag reduction values increases only 1 to 3 % even though the concentration of solution was added about 100 ppm. This occurred probably because of the formation of micelle in the solution which is not in a fully threadlike forms and the micelle networks are not fully established in solution to surpassed the degree of turbulent flow.