E.M. Cheng

THE USE OF DIELECTRIC MIXTURE EQUATIONS TO ANALYZE THE DIELECTRIC PROPERTIES OF A MIXTURE OF RUBBER TIRE DUST AND RICE HUSKS IN A MICROWAVE ABSORBER

A change in the relative proportions of a mixture of rubber tire dust and rice husks will cause a change in the mixtures electrical permittivity and its ability to absorb electromagnetic energy. An open- ended coaxial probe was used in conjunction with three dielectric mixture equations (the Kraszewski equation, the Landau equation and the Lichtenecker equation) to obtain the dielectric properties of a mixture of rubber tire dust and rice husks (RTDRH) over the frequency range of 7GHz to 13GHz. Lichteneckers equation for dielectrics proved to be a useful practical formulation for determining the efiective permittivity of homogeneous dielectric mixtures. The efiectiveness of these dielectric mixture equations in determining the efiective permittivity of RTDRH was investigated in this study. A newly developed mixture equation was derived based on these dielectric

Development of five port reflectometer for reflection based sensing system

Five-Port Reflectometer is a microwave passivedevice where it implements the six-port algorithm to measure the complex reflection coefficient of material under test (MUT) through reflection on interface between MUT and microwave sensor. Initially, the Six-Port Reflectometer (SPR) was introduced by Engen in 1977 and major component used insix-port technique was designed in many types. When Riblet and Hanssonproposed ring junction with 5 ports only on 1981. Six ports ring junction has been reduced to five ports. In this paper, a dual frequency five ports ring junction circuit was designed, simulated and fabricated for reflection based sensing system. The fabricated five port ring junction is operating at frequencies of 0.64u2005GHz and 2.42u2005GHz. The measured result had good agreement with the simulated results for dual frequencies in terms of magnitude and phase.

Microwave absorbing material based on rice husk ash/ CNTs composites

This paper presents the different type of microwave absorbing materials based on rice husk ash and carbon nanotubes (RHACNTs) composites. The microwave absorption and complex relative permittivity of RHACNTs composites were investigated in microwave frequency region X-band (8.2-12.4 GHz). A rectangular waveguide (WR-90) transmission line method was used to measure scattering parameter and Nicolson-Ross-Weir algorithm to calculate the complex relative permittivity (εr- jεr) of RHACNTs samples. The microwave absorption properties of rice husk ash with carbon nanotubes (0-5 wt %) was measured the modes of waveguides with perfectly conducting enclosures with metal backed plate. It was observed that the increase of carbon nanotubes (CNTs) influenced the εr and εr values. However, the different MAMs of RHACNTs composite have difference microwave absorption more than -10 dB at specify frequency. The complex relative permittivity and thickness of materials are important parameters for the microwave absorbing properties.

Study on Dielectric and Magnetic Properties of MWCNTs/Polyester Composites

This paper is to study the dielectric properties, magnetic properties, and dielectric conductivity of Multi-walled carbon nanotubes (MWCNTs) and polyester (PE) composites. The composites with different amount of MWCNTs (5-15%) have been studied in the Ku-Band range (12.4-18 GHz). The rectangular waveguide (WR-62) was used to measure the dielectric properties and magnetic properties of the samples. The results show the dielectric properties and conductivity of MWCNTs/PE composites is increasing with the MWCNTs filler increases. The real part of dielectric properties values increase from 5.5 to 26.6 with increasing the MWCNTs loading from 5 % to 15 %. The increasing of MWCNTs filler in the MWCNTs/PE composites does not effects on magnetic properties, the real part and imaginary part of magnetic properties are approximate to 1 and 0. The highest conductivity of 15 % MWCNTs loading is reach to 11.02 (S/m) at 18 GHz. Keywords: composites, dielectric properties, magnetic properties, conductivity

Conceptual Design for Oil Palm Evacuation to Improve Ergonomics Issues of Collecting Fresh Fruit Bunch

Oil palm evacuation are still labour dependent and room for mechanisation may still exist. With the importance of this industry as one of nation’s economic contribution the efforts are still considered viable. In order to reduce, improve and empower labours a new concept design was developed. A mock-up interaction was done in virtual environment in order to assess the ergonomic aspect of the design in order to determine the pros and cons of the concept design. The findings had led to a conclusion for a requirement of a more thorough assessment to assess human machine interaction in terms of biomechanical effects.

Comparative Study of Rapid Upper Limb Assessment (RULA) and Rapid Entire Body Assessment (REBA) between Conventional and Machine Assisted Napier Grass Harvest Works

Most of Napier grass industry in Malaysia is labored in small and medium scale. Therefore, the harvesting works are done manually by man power using conventional equipment such as sickle and machete. However, there are some efforts made to design the low cost equipment in assisting this Napier grass harvesting works. The aim of this study is to compare the Rapid Upper Limb Assessment (RULA) and Rapid Entire Body Assessment (REBA) performance in order to evaluate the certain body parts condition during harvesting works by using conventional equipment and innovation machine assisted. Based on survey, conventional harvesting method might increase the risk of low back pain (LBP) due to repetitive stooping posture. Furthermore, the back biomechanical load and force impact were also not handling wisely. The objective of this study is to prove that the usage of machine during harvesting works might improve the body posture especially on stoop level condition. Based on results, the overall RULA and REBA score are excellently improved as well as trunk position which is depicts the stooped level condition. Hence, the innovation of harvest machine could contribute to the Napier grass industry especially on small and medium entrepreneur.