A Comparative Study Between Weighing and Image Analysis Techniques for Predicting the Amount of Deposited Electrospun Nanofibres

Weighing and direct measurement are currently the two most common techniques used for estimating the amount of deposited nanofibres in electrospinning process. Nevertheless, due to its extremely small fibre size and mass, the task of measuring the weight or thickness of an electrospun nanofibres membrane is difficult and the results are arguable. This study evaluates the effectiveness of using greyscale image analysis for predicting the amount of deposited nanofibres compared to weighing technique. Polyvinyl alcohol electrospun nanofibres were collected at different deposition times on A4 black paper substrates. The substrates were weighed before and after deposition process and then scanned into 8 bit greyscale images. Analyses were carried out using ImageJ software, statistical analysis, high speed camera and scanning electron microscopy. At long deposition times, both techniques showed significant correlations between the measured values and deposition times. However, at short deposition times the weighing technique was found unreliable (p>0.05) compared to image analysis technique due to insignificant fibre masses compared to the weight variation of the substrates. Results suggest that image analysis technique was a better option to be used compared to weighing technique. This technique has the potential to be used as an automated online quality control in electrospun nanofibres manufacture

EXPERIMENTAL INVESTIGATION ON COOLING EFFECT OF SPHERICAL DIMPLED PROFILE ALUMINUM BLOCK BY THE TAGUCHI METHOD

Dimple profile plays a crucial role in enhancement of cooling process of various engineering application. This paper presents experimental investigation of convection heat transfer over spherical dimple on an aluminum block. In this study, an experimental investigation was carried out to observe the cooling effect under several conditions which are flow condition, dimple orientation, diameter of dimple, room temperature, air velocity, input of heat energy and condition of wind tunnel. A design of experiments technique was adopted in the form of orthogonal array L8 (23), Taguchi 2-Level approach. A total of 4 types dimpled surface are studied. The ANOVA results shows the room temperature is the major contributing factor towards rapid cooling process followed by wind tunnel condition, radius of dimple, air velocity, flow region and heat input. It was observed that the cooling time of 13 minutes can be achieved during laminar flow, 5 mm of dimple diameter, 60° angle of dimple orientation, 18 m/s of air velocity, 20 °C of room temperature