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 0.64 GHz and 2.42 GHz. The measured result had good agreement with the simulated results for dual frequencies in terms of magnitude and phase

Dielectric spectroscopy on mixture of rice husk, rice husk ash and rice bran from 4 Hz to 1 MHz

In this study, mixtures of rice husk/rice husk ashes (RHA) with RB on different ratios were prepared. Dielectric permittivity (ε'), loss factor (ε") and AC conductivity (σ') were measured in the frequency range of 4 Hz to 1 MHz in ambient temperature. Results for mixture of RHA and RB indicate that a dipolar relaxation occurring between 103 - 105 Hz and the peak is depressed and shifted to lower frequency as the RB content increases in the mixture. Moreover, AC conductivity decreases as the RB content increase. This may attributed to production of natural oil content from RB. In contrast, a dielectric characteristic for RH is generally not affected by the RB contents. This study explore dielectric characteristic of mixture between RH/RHA and RB in low frequency range because lack of literature is reported on low frequency response. Additionally, the potential application of RH/RHA and RB could be explored in effort to diminish waste disposal and enhance environmental protection

Overcoming issues of oil palm plantations manual1 work with ergonomic and engineering considerations

This paper is an initial study by reviewing current situation and researches to determine the issues with manual works in an oil palm plantation and the need for mechanisation with consideration for the application in the smallholder plantations. The smallholder oil palm plantations in certain areas, activities of harvesting, collecting, loading and pruning are still done using manual tools. The small land size ownership means it is not economical to acquire large machineries and current harvesting technologies to reduce the burden of the plantation works. Therefore, the current practise is still in favour. With the increasing awareness and role of ergonomic in recent days, a new solution for this current situation must be taken action not only for the benefit of human in terms of wellbeing but also towards the better gain margin as human productivity increases. Reviews on this paper is based on the three job scopes that had been identified high risk for musculoskeletal disorders, the use of manual tools and equipment, mechanised option for the manual tools and equipment, and issues with both manual and some developed mechanised solution

In vitro evaluation of finger's hemodynamics for vein graft surveillance using electrical bio-impedance method

Electrical bio-impedance measurement has great potential in many biomedical applications including vein graft surveillance. Studies have shown that thrombosis was the major cause of the vein graft failure. The meticulous skills of the surgeon and effective postoperative surveillance of vein graft remain the cornerstones of clinical success in the current surgical management of vein graft survival. Vascular blood flow is the key clinical indicators for the evaluation of patency of the vein graft and ensuring the patient's quality of life. In this work, electrical bio-impedance method has been proposed as an alternative to the existing surveillance method as it is non-invasive, portable, easy applicable in practice, fast response, radiation free, and required only low-cost instrumentation. It was employed to measure pulsatile changes in longitudinal bio-impedance to quantify arterial blood flow and blood volume. We expect that by measuring the changes in tissue bio-impedance which can be used to evaluate important peripheral hemodynamic, it allows the detection of early stage stenosis within vascular and vein graft as well as estimate its severity with predetermined normative data provided

CFD analysis on mismatched end-to-end internal diameter of RSVG models

A digital arterial disease in upper extremity is uncommon happened compare to arterial disease in lower extremity. A surgical vein graft interposition is performed as revascularization procedure. However, mismatching between end-to-end internal diameter of reverse saphenous vein graft (RSVG) and existing digital artery cause blockage in RSVG vessel. In previous study, size discrepancy (small to large) in vessel causes the abnormal blood flow and will initiate the thrombosis formations as stated by Rory F. et al. Furthermore, their previous study is also supported by clinical theory as written in Wilmer W. et al. and Krishnan B. Chandran et al.s’ text books. The main goal of this study is to analyze the relationship the patterns of blood flow through mismatching between end-to-end internal diameter of RSVG models and existing digital artery (large to small) with effect to the initiation of thrombus formation in RSVG models. A Three-dimensional Computational Fluid Dynamic (3-D CFD) method is employed to investigate blood flow velocity, blood pressure gradient and wall shear stress (WSS) on ideal straight (well matched between internal diameter of RSVG and recipient arteries) and internal diameter mismatched of end-to-end RSVG models. In this experiment, we expect that steady state laminar blood flow demonstrates abnormal flow pattern in mismatched internal diameter RSVG models compared to an ideal straight model. As conclusion, any abnormal blood flow pattern will initiate the formation of thrombus and reduce the vein graft survival

Performance Factors of the Photovoltaic System: A Review

Photovoltaic (PV) technology is one of the clean sustainable energy technology which sourced from the sun. However, there are many issues that can potentially degrade the system. This paper extensively discusses on the hybrid system power generation for the photovoltaic (PV) system. In addition, this paper also reviews the factor that affecting the photovoltaic system performance including the types of PV cell, the effect of ambient condition, system components, and the power quality characteristics. The performance of the monocrystalline type greater than the polycrystalline type around 5-7%. The usage of an inverter gives an impact with 8-20% of total energy losses. Finally, this paper summarises the future research work needed to overcome the drawback of the available photovoltaic systems

Performance Factors of the Photovoltaic System: A Review

Photovoltaic (PV) technology is one of the clean sustainable energy technology which sourced from the sun. However, there are many issues that can potentially degrade the system. This paper extensively discusses on the hybrid system power generation for the photovoltaic (PV) system. In addition, this paper also reviews the factor that affecting the photovoltaic system performance including the types of PV cell, the effect of ambient condition, system components, and the power quality characteristics. The performance of the monocrystalline type greater than the polycrystalline type around 5-7%. The usage of an inverter gives an impact with 8-20% of total energy losses. Finally, this paper summarises the future research work needed to overcome the drawback of the available photovoltaic systems

The effect of physical changes in a furnished indoor environment on Wireless Local Area Network (WLAN) signals

This paper describes the investigation of the effect on the Wireless Local Area Network (WLAN) signals due to fixed and non-fixed variables in the indoor environment. The measurement system consisted of a spectrum analyzer and a log-periodic antenna. Line-of-sight (LOS) propagation and non-line-of-sight (NLOS) propagation (in furnished rooms) were discussed. All the measurement sites mentioned in this paper are located in the Division of Information Technology at Universiti Putra Malaysia. The furnished rooms included a teaching laboratory, a computer laboratory, and an operating office plus a server room. The effects of the various types of materials at the measurement sites also are described here

An overview of the oil palm empty fruit bunch (OPEFB) potential as reinforcing fibre in polymer composite for energy absorption applications

The oil palm empty fruit bunch (OPEFB) natural fibres were comprehensively reviewed to assess their potential as reinforcing materials in polymer composites for energy absorption during low-velocity impact. The typical oil palm wastes include trunks, fronds, kernel shells, and empty fruit bunches. This has a tendency to burden the industry players with disposal difficulties and escalates the operating cost. Thus, there are several initiatives have been employed to convert these wastes into value added products. The objective of this study is to review the potential of oil palm empty fruit bunch (OPEFB) as natural fibre polymer composite reinforcement to absorb the energy during low-velocity impact as another option for value added products. Initially, this paper reviewed the local oil palm waste issues. Previous research works on OPEFB polymer composite, and their mechanical characterization is appraised. Their potential for energy absorption in low-velocity impact application was also elaborated. The review suggests high potential applications of OPEFB as reinforcing materials in composite structures. Furthermore, it is wisely to utilize the oil palm biomass waste into a beneficial composite, hence, promotes the green environment