Muhammad Abu Bakar Sidik

Analytical calculation of sensing parameters on carbon nanotube based gas sensors

Carbon Nanotubes (CNTs) are generally nano-scale tubes comprising a network of carbon atoms in a cylindrical setting that compared with silicon counterparts present outstanding characteristics such as high mechanical strength, high sensing capability and large surface-to-volume ratio. These characteristics, in addition to the fact that CNTs experience changes in their electrical conductance when exposed to different gases, make them appropriate candidates for use in sensing/measuring applications such as gas detection devices. In this research, a model for a Field Effect Transistor (FET)-based structure has been developed as a platform for a gas detection sensor in which the CNT conductance change resulting from the chemical reaction between NH3 and CNT has been employed to model the sensing mechanism with proposed sensing parameters. The research implements the same FET-based structure as in the work of Peng et al. on nanotube-based NH3 gas detection. With respect to this conductance change, the I–V characteristic of the CNT is investigated. Finally, a comparative study shows satisfactory agreement between the proposed model and the experimental data from the mentioned research.

Induced voltage on objects under six-phase transmission line

This paper presents results of an experimental investigation on voltage induced on objects under a six-phase transmission line due to line switching incidences. In this work, the voltage induced on a vertical receiver and a pipeline due to line energization and de-energization in a six-phase power transmission line system is reported. The research was carried out using a six-phase transmission line mock-up system with ratio of 5/132 kV. The results showed that the induced voltage on the objects is less than 4 kV. In addition the high induced voltage experienced by the vertical receiver was from the left side of the phase composition while the pipeline experienced higher induced voltage from the right side phase composition.

Assessing induced sheath voltage in multi-circuit cables: Revising the methodology

Flow of current in a cable conductor generates a magnetic field which could induce current flow in the metallic cable shield or sheath. This paper examines induced voltage calculation in multi-circuit of the cables with the hope of proposing new methodology for induced sheath voltage computation in metallic shield of a single-core power cable operating in a triple circuit. This study considers a few examples to demonstrate the method of examining the induced voltage in single, double and triple-circuits. The calculated values for induced voltages were 0.079 V/m, 0.074 V/m and 0.068 V/m for triple, double and single circuit. It is found that induced sheath voltage increased with the increase in number of the cables.

Chemical Analysis on the Effect of Pulsed Electric Fields in Pineapple Juices Preservation

The application of high voltage electric field for preservation of fruit juices has a promising scope in the food industry. The pulsed electric field (PEF) is an innovative non- thermal technique and free from bio-toxic effects. The technique has a viable solution of the problem yet faced in the food industry to prolong life and preserve and maintain quality with natural properties of the liquid food and beverages. In this study, we have treated the pineapples juice samples by different strengths of pulsed electric field such as 10, 20 and 30kV/cm for 5 minutes in each test. This study used new design of helix treatment chamber with three different lengths of 20, 30and 50cm. In these experiments, all samples were kept in same and normal condition with a temperature around 25-26 andthe humidity was between 55 and 65%. Then the observation based on chemical tests such as pH, conductivity, salinity and total dissolved solids (TDS) was recorded for all samples before and after the test. Based on results obtained by chemical parameters suggest that the injection on pulsed electric field of 30 kV/cm by the 50 cm treatment chamber has the best effect on pineapple juices characteristic as compared to the other value. The result of this experiment is encouraging and supportive of the better way for pasteurization the pineapple juices and increasing longevity of pineapple juices.

Modelling and optimization of simultaneous AC-DC transmission to enhance power transfer capacity of the existing transmission lines

With ever-growing population, the demand of electric power is also increasing day by day. To meet this increasing demand, the power transferred should also increase. However, the existing EHV transmission lines cannot be loaded up to their thermal limits because of the considerations of their transient stability. To address this issue simultaneous power transfer scheme came into existence. With this scheme it is possible to load the transmission lines close to their thermal limits, thus increasing the power transfer capacity of the line. This is done by the transferring AC power with DC current superimposed on it. A double circuit line is converted into composite AC-DC line which will be used for simultaneous AC-DC transmission. In this work, simple mathematical model of composite line is developed and analysed to track down the conditions for maximum power transfer. Developed mathematical approach is also compared with the existing graphical method for calculating maximum power transfer. The results obtained from mathematical model are found to be in close proximity to those obtained by graphical analysis.

Small scale test model to study impulse flashover and attachment pattern of protected building structures

The consequences due to lightning on different building shapes needs a comprehensive knowledge in order to provide the information to the common man. This paper is mainly concern with the development of a small scale model to study impulse flashover and attachment pattern of protected building structures due to lightning strike. The lightning strike pattern of buildings is based on the practical experimental work in high voltage laboratory. Three models are chosen for the study and it was found that the LAT arrangement on a flat roof top square building and grounding terminal for the model must follow certain procedures in order to achieve 100% LAT attachment. The model that has been developed is useful where LATs upward streamers analysis can be applied to analyse in term of the electric field effect on the lightning air terminal and the entire building structure interaction with lightning strikes.

Evaluation and mitigation of underground gas pipeline coating stress due to nearby lightning stroke

Rapid economic developments have forced power networks and pipeline networks to share the same pathway. Induced voltages and currents appear on pipelines running parallel with high voltage transmission line when the transmission line is hit by lightning strike. In this study, a simulation had been carried out to determine the first lightning stroke effect on an underground pipeline coating stress. CDEGS software was used to solve Maxwell equations; in particular, HIFREQ and FFTSES tools were utilized. A 2-km underground pipeline and a 345-kV transmission line (TL) tower had been modeled. A suitable TL-pipeline distance need to determined based on lightning current, surrounding soil properties, and coating withstand voltage. In addition, horizontal and vertical rods are able to reduce the overvoltage across the coating. The first layer soil resistivity and thickness are important factors to be considered when carrying out mitigation in a non-uniform soil.

AC breakdown strength enhancement of LDPE nanocomposites using atmospheric pressure plasma

Polymer nanocomposites have been identified to possess superior electrical insulation properties compared to its base polymer. However, weak interfacial interaction between the nanoparticles and the host polymer matrices would result in poor insulation properties. In this study, the surfaces of Boron Nitride (BN) nanoparticles were treated with atmospheric pressure plasma discharge to strengthen the interface between the low density polyethylene (LDPE) matrices and BN nanoparticles. Furthermore, AC breakdown strengths of the untreated and treated LDPE nanocomposites were measured according to ASTM D149 standard. The obtained results were analyzed with 2-parameter Weilbull distribution. Moreover, the treated and untreated nanocomposites were characterized using Fourier Transform Infrared (FTIR) Spectroscopy in order to characterize the functional groups in LDPE nanocomposite samples after subjected to plasma discharges. It is shown that hydrogen bonds are created in the functional groups of the plasma treated LDPE nanocomposites. The results also show that the AC breakdown strength of plasma treated LDPE nanocomposites sample was improved compared with the untreated LDPE nanocomposites.

On the interaction of 132 kV transmission system with communication line: Street cabinet resistivity evaluation

Occurrence of surge voltages and surge currents in low-power circuits is initiated primarily because of two sources, i.e, natural lightning and switching phenomena; the other source of surge occurrence is possibly due to the interaction of power systems and communication system. Results have indicated that soil resistivity is crucial in determining the adequacy of an earthing system. In region with the highest resistivity, the EPR and the scalar potential of the cabinet are very high. Remarkable low induced voltages at 200 m away from the power line when subjected to a single phase-to-earth fault was observed. At 50 m away, step and touch voltages could be dangerous due to the nature of soil in the vicinity. In addition, a 132 kV double circuit transmission line sharing the same corridor with a telecommunication line was also investigated and have also shown the induced voltages in the order of thousand volts on the cable due to a single phase-to-earth fault. Cables must be protected from such dangerous voltages. During normal peak load conditions voltages are considered not to inflict any damage to equipment and livestock.

AC breakdown strength performance of plasma treated mineral oil-based nanofluids

Nanofluids have been identified to be one of the suitable approaches to increase the breakdown strength of transformer oil. However, the nanofluids tend to form sediment which nullifies its full capabilities in increasing the electrical properties such as higher AC breakdown strength. In view of foregoing, this paper presents an approach to enhance the AC breakdown strength of the transformer oil by using plasma treated silica nanoparticles to form plasma treated nanofluids. The surface of silica nanoparticle was functionalized by using atmospheric pressure plasma discharge to enhance the interfacial interaction in order to improve the sedimentation issue in nanofluids. Plasma treated nanoparticles with desired surface functionality can strongly interact with liquid molecules with better dispersed into the base fluid to form a stable suspension. The AC breakdown strength of oil samples before and after surface modification of nanoparticles were measured accordance to IEC 60156 standard. Based on obtained results, it was found that the plasma treated nanofluids had higher AC breakdown voltage compared to the pure oil and the untreated nanofluids.