No abstract

Malaysia is aiming to reduce the dependency on oil and gas by increasing the utilization of renewable energy. One of the promising renewable energy available is wind energy. Malaysia is located near the equator which is situated in a low wind speed region with an annual mean wind speed of 1.2-4.1 m/s. However, Malaysia also experiences two different monsoon seasons which is the southwest monsoon and the northeast monsoon. Wind speed during the southwest monsoon season can reach 7 m/s while the wind speed during the northeast monsoon can exceed 15 m/s. Limited researches and studies had been done to investigate the potentiality of wind energy in Sarawak, Malaysia. In this paper, modelling and simulation of different wind energy conversion system (WESC) using different generators operating under the same parameters will be carried out using MATLAB/SIMULINK to investigate the efficiency of the generators. PMSG has shown to be more efficient over SCIG and DFIG for lower wind speed although all of them eventually reaches the similar efficiency. Efficiency of SCIG, DFIG and PMSG for rated wind speed are 66.25%, 69.38% and 71.88% respectively.

A circular cylinder resonator modal analysis is applied to Vertical Cavity Surface Emitting Lasers (VCSELs) to obtain a resonance mode chart to identify possible lasing spectra. For the first time a two-dimensional (radial and azimuthal) calculation of the inversion population distribution in the device is done, inclusive of current spreading, carrier diffusion, (bi-molecular) spontaneous recombination, and stimulated recombination to account for above threshold operation. Analysis of corresponding modal gain competition is used to indicate possible lasing mode selection.

Dielectric barrier discharge (DBD) represent their wide application in controlling aerodynamic flow by plasma actuators. Their effectiveness is affected by the shape, type size, and thickness of electrodes. This paper investigates the influence of the number of electrodes on the electrical functioning of surface DBD plasma actuator. For this purpose, five different configurations of plasma actuator with varying electrodes number from 4 to 8 are tested. The gap between the electrodes and the length and width of each electrode remains constant in all these configurations. It was found that on increasing the number of electrodes and the applied frequency (1 kHz to 5 kHz) the value of maximum withstand voltage was decreased. However, the discharge power was increasing slightly on increasing the number of electrodes. This slight change in discharge power resulted in the significant plasma formation on the surface of the plasma actuator, the effect was visually captured by a CCD camera.

No abstract