Design and Evaluation of Submersible 11/0.415kV Distribution Substation for Flood Prone Areas

Flood levels exceeding 2 metres above ground level has been observed causing electrical equipment in the 11/0.415kV substation to be fully submerged. This caused widespread supply disruption as the equipment need to be switched off due to safety reasons and prevention of further equipment damage. The use of submersible equipment and accessories has been identified as one of the mitigation methods to ensure continuous electrical supply during flood events. A research project was undertaken to develop the design criteria of the selection of submersible equipment and accessories as well as to develop the test method and evaluate the selected submersible equipment and accessories in a substation configuration. All the equipment could continuously operate in ON condition during the wet test. However, design improvements are suggested for the submersible switchgear and feeder pillar for better performance during and after flood events

Corona Detection Using Wide Band Antenna and Time Delay Method

IEEE Std 100-2000 defines corona as a luminous discharge due to ionization of the air surrounding a conductor caused by a voltage gradient exceeding a certain critical value. It occurs when the insulating material begins to ionize or conduct due to voltage stress. Corona brings a lot of damages such as corrosion, loss inoverhead transmission lines and electromagnetic interference. Monitoring of corona may reduce the maintenance and replacement cost of electrical equipment. The motivation of this experiment is to calibrate corona detector antennas in the future. The error obtained will determine the efficiency of the antenna to detect and locate potential coronas in electrical equipment in a substation with switchgears or transformers. The operation bandwidth of the antenna is 320MHz to 1.20GHz making it useful to detect and corona. The measurement method of utilizing delay between signals first peak is effective with average 4.76% error with maximum 10.0% error recorded. This may be used to develop a corona online measuring system in the future

The mechanical performance of sugar palm fibres (Ijuk) reinforced phenolic composites

Sugar palm fibres are one of the natural fibres which have many features and need further study to understand their properties. The aim of this work is to investigate the flexural, compressive and impact properties of sugar palm fibres reinforced phenolic composites. Sugar palm fibres were used as a filler (particle size 150 μm) and with loading of 0, 10, 20, 30, and 40 vol.%. The fibres were treated by sea water and then fabricated into composites by hot press technique. Flexural, compressive, and impact tests were carried out as per ASTM D790, ASTM D695-08a, and ASTM D256 standards, respectively. Scanning electron microscopy (SEM) was used to investigate the morphology and the interfacial bonding of the fibres-matrix in composites. The results show that the mechanical properties of the composites improve with the incorporation of fibres. The composite of 30 vol.% particle loading exhibit optimum values which are 32.23 MPa, 61.66 MPa, and 4.12 kJ/m2 for flexural, compressive, and impact strength, respectively. This was because good compatibility of fibre-matrix bonding. Consequently, sugar palm fibre is one of the prospective fibres and could be used as a potential resource to reinforcement polymer composite

Application of region growing segmentation method for mangrove zonation at Pulau Kukup, Johor

The anticipated impact of Sea Level Rise (SLR) for the next century has been studied for the past long years. Prolonged submergence and changes in tidal inundation frequency changed the intertidal community landscape including the mangroves zonation pattern. This study aims to identify the mangrove species distribution at Pulau Kukup, Johor using a high resolution, Worldview-2 satellite data. Mangrove extent was extracted from multispectral and panchromatic images using region growing segmentation method. Several thresholds were used to identify the best-fit segmentation parameters. Eleven plots of 100m transects were established in the study area to sample the representative mangrove trees. The type of mangrove species, tree height, Diameter at the Breast Height (DBH), elevation, coordinate location and the sediment sample were collected during the field survey based on Point-Centre-Quadrate Method (PCQM). The general characteristics of mangrove tree were investigated and sampled from 186 mangrove trees. Rhizophoraapiculata and R.mucronata were found dominating the outer part of the mangrove island facing the seaward area. From the field analyses, the relative density of Rhizophoraapiculata and R.mucronataare 41.9% and 16.7% respectively. The mangrove characteristic and coordinate locations were then mapped out and used as a reference point for training processes. The image classification is determined based on Bhattacharyya method and the mangrove zonation pattern was mapped from the result

Three-phase series resonant DC-DC boost converter with double LLC resonant tanks and variable frequency control

This paper proposes a three-phase inverter combined with two LLC resonant tanks series resonant DC-DC boost converter with variable frequency control. The three-phase inverter side of the proposed circuit is connected to identical two-level LLC tanks to ensure balanced resonant currents. The proposed converter requires less switching devices and transformers as compared to the conventional interleaved LLC resonant converter, which competitively offers higher efficiency and reduced size and cost. Furthermore, the proposed converter works above the resonant frequency to achieve zero voltage switching (ZVS) for the entire operating frequency range {(42.5kHz < }{f}{s}{ < 50kHz)} for all switches. Variable frequency controller is considered in order to obtain better stability for diverse loads. Therefore, the proposed converter will have the ability to respond to the load changes by varying the switching frequency to the value that fulfils the requirement. In order to verify the improvement of the proposed converter, the converter performance is compared to conventional interleaved LLC resonant converter. The theoretical outcomes are confirmed through simulation studies using MATLAB/SIMULINK and validated experimentally using a laboratory prototype. Selected results are presented to verify the effectiveness of the proposed converter

All static spherically symmetric perfect fluid solutions of Einstein's Equations

An algorithm based on the choice of a single monotone function (subject to boundary conditions) is presented which generates all regular static spherically symmetric perfect fluid solutions of Einstein's equations. For physically relevant solutions the generating functions must be restricted by non-trivial integral-differential inequalities. Nonetheless, the algorithm is demonstrated here by the construction of an infinite number of previously unknown physically interesting exact solutions.Comment: Final form to appear in Phys Rev D. Includes a number of clarification

How strong is the evidence for accelerated expansion?

We test the present expansion of the universe using supernova type Ia data without making any assumptions about the matter and energy content of the universe or about the parameterization of the deceleration parameter. We assume the cosmological principle to apply in a strict sense. The result strongly depends on the data set, the light-curve fitting method and the calibration of the absolute magnitude used for the test, indicating strong systematic errors. Nevertheless, in a spatially flat universe there is at least a 5 sigma evidence for acceleration which drops to 1.8 sigma in an open universe.Comment: 16 pages, 3 figure

LIFE EXTENSION TECHNIQUE FOR WELDED STRUCTURE USING HFMI/PIT: A REVIEW ON PAST AND CURRENT RESEARCHES WITH APPLICATIONS

In this paper, High Frequency Mechanical Impact (HFMI) using Pneumatic Impact Treatment (PIT) which can be applied for new or aging welded structure towards asset integrity will be discussed. The technology HFMI/PIT which falls under post weld treatment process is primarily aimed to enhance fatigue life and to strengthen welded joint. At first, the basic principle on fatigue of welded structure based on the IIW Recommendation will be briefly described. Further, various investigations conducted by prominent research universities or institutions and various industrial applications in European countries will be reviewed and discussed. Lastly, the current research on application of HFMI/PIT carried out under Advanced Manufacturing Technology Excellence Centre (AMTEx) at Faculty of Mechanical Engineering UiTM Shah Alam will be presented. As conclusion, it is stated that HFMI/PIT can be applied for extending the structural life and also for design optimization

LIFE EXTENSION TECHNIQUE FOR WELDED STRUCTURE USING HFMI/PIT: A REVIEW ON PAST AND CURRENT RESEARCHES WITH APPLICATIONS

In this paper, High Frequency Mechanical Impact (HFMI) using Pneumatic Impact Treatment (PIT) which can be applied for new or aging welded structure towards asset integrity will be discussed. The technology HFMI/PIT which falls under post weld treatment process is primarily aimed to enhance fatigue life and to strengthen welded joint. At first, the basic principle on fatigue of welded structure based on the IIW Recommendation will be briefly described. Further, various investigations conducted by prominent research universities or institutions and various industrial applications in European countries will be reviewed and discussed. Lastly, the current research on application of HFMI/PIT carried out under Advanced Manufacturing Technology Excellence Centre (AMTEx) at Faculty of Mechanical Engineering UiTM Shah Alam will be presented. As conclusion, it is stated that HFMI/PIT can be applied for extending the structural life and also for design optimization