Baharudin Yatim

Thermal performance of the double-pass solar collector with and without porous media

This paper presents the thermal performance of a double-pass solar collector with and without porous media in the second or lower channel of the collector. The experimental setup has been designed to study the thermal performance over a range of design and operating conditions. Several important relationships between the design and operating conditions have been obtained. These relationships effect the thermal performance of the double-pass solar collector. The relationships include the effect of changes in upper and lower channel depth on the thermal efficiency with and without porous media. Moreover, the effects of mass flow rate, solar radiation, and temperature rises on the thermal efficiency of the double-pass solar collector have been studied. The study concluded that the presence of porous media in the second channel increases the outlet temperature, therefore increases the thermal efficiency of the systems.

Smart antenna UKM testbed for digital beamforming system

A new design of smart antenna testbed developed at UKM for digital beamforming purpose is proposed. The smart antenna UKM testbed developed based on modular design employing two novel designs of L-probe fed inverted hybrid E-H (LIEH) array antenna and software reconfigurable digital beamforming system (DBS). The antenna is developed based on using the novel LIEH microstrip patch element design arranged into uniform linear array antenna. An interface board is designed to interface to the ADC board with the RF front-end receiver. The modular concept of the system provides the capability to test the antenna hardware, beamforming unit, and beamforming algorithm in an independent manner, thus allowing the smart antenna system to be developed and tested in parallel, hence reduces the design time. The DBS was developed using a high-performance floating-point DSP board and a 4-channel RF front-end receiver developed in-house. An interface board is designed to interface to the ADC board with the RF front-end receiver. A four-element receiving array testbed at 1.88–2.22 GHz frequency is constructed, and digital beamforming on this testbed is successfully demonstrated.

Diurnal pattern of global solar radiation in the Tropics : a case study in Malaysia

Global solar radiation patterns in Bangi (2°56′7.3″N, 105°47′0.2″E), Malaysia are discussed. The frequency of occurrence of the various solar radiation patterns observed over a 5-year period is derived. These observations will provide useful information for the design of solar energy systems and equipment for installation in tropical countries having a similar global solar radiation pattern.

Development of Electromagnetic Band Gap Structures in the Perspective of Microstrip Antenna Design

Electromagnetic band gap (EBG) technology has become a significant breakthrough in the radio frequency (RF) and microwave applications due to their unique band gap characteristics at certain frequency ranges. Since 1999, the EBG structures have been investigated for improving performances of numerous RF and microwave devices utilizing the surface wave suppression and the artificial magnetic conductor (AMC) properties of these special type metamaterial. Issues such as compactness, wide bandwidth with low attenuation level, tunability, and suitability with planar circuitry all play an important role in the design of EBG structures. Remarkable efforts have been undertaken for the development of EBG structures to be compatible with a wide range of wireless communication systems. This paper provides a comprehensive review on various EBG structures such as three-, two-, and one-dimensional (3D, 2D, and 1D) EBG, mushroom and uniplanar EBG, and their successive advancement. Considering the related fabrication complexities, implementation of vialess EBG is an attractive topic for microwave engineers. For microstrip antennas, EBG structures are used in diversified ways, which of course found to be effective except in some cases. The EBG structures are also successfully utilized in antenna arrays for reducing the mutual coupling between elements of the array. Current challenges and limitations of the typical microstrip antennas and different EBG structures are discussed in details with some possible suggestions. Hopefully, this survey will guide to increasing efforts towards the development of more compact, wideband, and high-efficient uniplanar EBG structures for performance enhancement of antenna and other microwave devices.

Design of an experimental solar assisted dryer for palm oil fronds

This paper presents the design of an experimental solar assisted dryer for palm oil fronds. The system consists of collector, a dryer, an auxiliary burner and a fan. The collector is of the double-pass configuration with porous media in the lower channel. The dryer is of the batch type where hot air introduced from the bottom. The size of the collector is 120 cm width and 240 cm in length. The upper and lower channels are adjustable for optimal operations. The size of the dryer is 100 cm width, 100 cm long and 80 cm in height. The project is funded by the Malaysian government and will be carried out at the Solar Energy Research Park University Kebangsaan Malaysia, Bangi.

Fabrication and Irradiance Mapping of a Low Cost Solar Simulator for Indoor Testing of Solar Collector

The fabrication and testing of a solar simulator for indoor testing of solar collector are described. Consisting of Philips 500 W halogen lamps with built-in reflector, which are arranged at 30 cm apart, the system covers a test area suitable for a solar collector of size 120 cm by 53 cm. The height of the lamps above the solar collector under test is set to 160 cm. Measurement of the uniformity of the irradiance over the test area has been made. Four sets of irradiance mapping were performed at 466, 580, 686, and 804 W/m2 , yielding at each point the irradiance uniformity percentage of 8.9, 7.6, 6.9, and 7.8%, respectively. The infrared radiation produced by the lamps was filtered by air flowing over the test area.

Design of broadband multi-slotted microstrip patch antenna for wireless system

A multiple slot microstrip patch antenna for wireless communication is presented. In this paper, inverted microstrip patch antenna, direct probe feed technique and the novel multiple shaped patch is integrated. This antenna offers low profile, wide bandwidth, high gain, and compact antenna element. The proposed multi-slotted microstrip patch antenna achieves a fractional bandwidth of 27.89% (1.82 to 2.41 GHz) at 10 dB return loss. The maximum achievable gain of the antenna is 10.01 dBi. The proposed patch has a compact dimension of 0.557 lambda0 times 0.374 lambda0 (where lambda0 is the guided wavelength of the center operation frequency).

Analysis of broadband slotted microstrip patch antenna

In this paper, a novel multiple slot microstrip patch antenna with enhanced bandwidth is presented. The design adopts contemporary techniques namely; probe feeding, inverted patch structure and multiple slotted patch. The composite effect of integrating these techniques and by introducing the novel multiple shaped patch, offer a low profile, wide bandwidth, high gain and compact antenna element. The proposed patch has a compact dimension of 0.707 lambda0 times 0.354 lambda0 (where lambda0 is the guided wavelength of the center operation frequency). With the proposed concept, an antenna prototype is simulated and analyzed. The proposed antenna achieves a fractional bandwidth of 27.15% (1.91 to 2.51 GHz) at 10 dB return loss while maintaining a maximum gain of 10.5 dBi. The design is suitable for array applications especially for base station.

Chicken dung biogas power generating system in Malaysia

A study on the possibility of developing biogas power generating system from layers farming is presented. The farm consists of 300,000 heads of layer producing 9000 kg/day dry weight of the chicken dung. The gas will be used in a combined heat and power system to meet the energy requirements of the farm. The solid residue from the biogas digestor will be sold as fertiliser. It is envisaged that this study will promote wider application of the system in Malaysia.

GPS water vapor monitoring and TroWav updated for ENSO studies

The GPS receiver and the meteorology sensors have been installed at Universiti Malaysia Sabah (UMS), Kota Kinabalu (UMSK: 6.03°N, 116.12°E and 63.49 m) for study a climate condition that has associated with El Niño Southern Oscillation (ENSO). The atmospheric precipitable water vapor (PWV) derived from GPS technique was used as an indicator of ENSO detection. In the processing, the Niell Mapping Function (NMF) used to map the atmospheric delay from zenith to the line-of-site was updated using the Vienna Mapping Function (VMF). With GPS antenna co-located with meteorological sensors, the comparison of GPS PWV with time-dependent surface pressure and sea surface temperature (SST) during the first ten weeks observation found that surface pressure is opposed to the PWV changes.