Maziah Mohamad

Prediction of the Heat Transfer Coefficient in a Small Channel with the Superposition and Asymptotic Correlations

Heat transfer coefficient as an important characteristic in heat exchanger design is determined by the correlation developed from previous experimental work or accumulation of published data. Although discrepancies still exist between the existing correlations and practical data, several researchers claimed theirs as a generalized heat transfer correlation. Through optimization method, this study predicts the heat transfer coefficient of two-phase flow of propane in a small channel at the saturation temperature of 10∘C using two categories of correlation — superposition and asymptotic. Both methods consist of the contribution of nucleate boiling and forced convective heat transfer, the mechanisms that contribute to the total two-phase heat transfer coefficient, which become as two objective functions to be maximized. The optimization of experimental parameters of heat flux, mass flux, channel diameter and vapor quality is done by using genetic algorithm within a range of 5–20kW/m2, 100–250kg/m2s, 1.5–3mm ...

Periodic Cubic Spline on Motion of Five-Link Human Bipedal Model Using Nonlinear Predictive Control

This paper studies about the performance of periodic cubic spline applied on the nonlinear predictive control (NPC) based on receding-horizon cost function optimization. The five-link human bipedal model includes a torso and two legs which has a thigh and a shank in every leg. The periodic cubic spline is used to achieve smooth walking trajectories of every joint in the bipedal model in the sagittal plane. The results show that the tracking error after using periodic cubic spline is smaller than the tracking error before using periodic cubic spline.

Adjustable Acoustical Performance Based on Deformable Origamic Shapes: A Preliminary Experimental Investigation

This paper describes a preliminary investigation on the possible use of deformable origamic shapes as a technique to provide adjustable acoustical performance in multi-purpose hall. The term ‘deformable’ means that the origamic shape undergoes deformation which automatically resulted into the change of its geometrical configurations. The experimental investigation has been carried out on three types of origamic shapes with several geometrical configurations. The measurement tests were conducted in a reverberation room and in accordance to ISO 354:2003 Measurement of Sound Absorption Coefficients in a Reverberation Room. Findings from the preliminary investigation show good trends indicating that the origamic shapes have the capability of adjusting the sound absorption coefficients by varying their geometrical configurations. Following those results, future works with details investigation will be undertaken as to validate the preliminary results.

Development of a Hand-Arm Model to Emulate Tremor Handwriting Behavior

Patients with hand tremor may find difficulties in performing their routine task especially writing. The worse when the tremor becomes severe. In this paper, a hand-arm model has been developed to study the behavior of tremor while performing handwriting. Regarding the study, the hand of patient oscillates in a perpendicular direction to the forearm rather than other directions due to hand support while the handwriting is performed. A miniature accelerometer patched to the writing device and acceleration data recorded have then been examined by power spectral density (PSD). For hand-arm model setup, the DC motor was used to emulate the hand movement to draw a straight line by connecting the linear screw thread to the writing mechanism. For writing mechanism, there are two parts, holder to hold the pen and Linear Voice Coil Actuator (LVCA) to resemble hand tremor conditions. By injecting tremor data to the LVCA the acceleration is measured once again by attaching a miniature accelerometer to the writer device. The findings show that the model can emulates hand tremor by considering its acceleration and frequency range from PSD based on record actual tremor data as references. The hand-arm model furthers can be a research conduct to design a writing device that can be cancelled or at least suppress the tremor.