19672 research outputs found
Sort by
Graphene oxide-based optical waveguide for moisture sensing in transformer oil
No full textWe report on moisture detection in transformer oil based on an optical waveguide fabricated using graphene oxide (GO). The SU-8 polymer channel waveguide was coated by GO film, using a drop-casting technique. Here, for the polarized light, high absorption of transverse electric (TE) was achieved for the proposed sensor at wavelength 1550 nm. Changes in TE-polarized light absorption by the device were measured at varying water contents. Experiments were carried out for water contents in oil in the range of 16–21 ppm as well as immiscible (free) water in oil. Our observations showed a difference in the results trend obtained for different relative water contents. The TE-transmission power increased linearly with higher water content in transformer oil. A power change of +0.90 dB/ppm of water content in transformer oil was measured within the range tested. A simulation analysis using the finite element method FEM was also carried out. The proposed sensing mechanism can be used under these sensing conditions. This approach also has a fast response time as well as high sensitivity. © 2019 Elsevier B.V
Distribution and contamination assessment of potentially harmful elements (As, Pb, Ni, Cd) in top soil of Penang Island, Malaysia
No full textThis study discusses the distribution and contamination levels of potentially harmful elements (As, Pb, Ni, and Cd) in the urban top soil of Penang Island, one of the most important urban areas in Malaysia. The total surface area of Penang Island is 297 km2. Thirty-one surface soil samples (0–20 cm) were collected, digested and analysed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) for As, Pb, Ni, and Cd. The result showed that the mean concentrations of selected metals in soils were arranged in the following decreasing order: Pb > As > Ni > Cd. In terms of different soil types, soils derived from quaternary deposit have higher mean concentration of Pb, Ni, and Cd as compared to the granite residual soils which accumulate higher mean concentration of As. On the spatial distribution maps, As, Pb, Ni, and Cd are mainly concentrated in the north-to-north eastern areas of Penang Island and near to the main city, which are characterized by major residential and business areas. Thus, it suggests that the anthropogenic source is the main contributor to the As, Pb, Ni, and Cd in the top soil of Penang Island. Both Pearson correlation analysis and principal component analysis showed a strong positive correlation between Pb and Cd which indicated that they may be derived from a similar source. The contamination factor assessment indicates moderate contamination level for Pb and Ni and no element enrichment level for As and Cd. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature
Protection Coordination Toward Optimal Network Reconfiguration and DG Sizing
No full textResearch on network reconfiguration (NR) considering distributed generations (DG) is typically concerns on the issues of power loss, voltage deviation, DG sizing as well as its placement, which are important and required in the planning stage. On the other hand, another important aspect which often neglected in this stage is coordination of protection devices which is essential to prevent the network from damages following system breakdown. Without sufficient attention given to the protection coordination during NR, there is a possibility for the protective devices to miscoordinate and consequently lead to system blackout, due to changes in current flow and fault level. Therefore, this paper proposed an NR method for distribution networks with DG, incorporating protection devices. The proposed method aims to find the optimal configuration and DG size with minimum power loss, and at the same time ensuring protective devices operate correctly during normal and fault condition. Constraints on protection coordination and DG size are explicitly formulated in the proposed method. The validity of the proposed method is analyzed on three commonly used IEEE 33-bus, 69-bus and 118-bus distribution systems, employing the firefly algorithm (FA) and evolutionary programming (EP) algorithm. Comparative studies are done to prove the validity and robustness of the proposed method. © 2013 IEEE
Beetle abundance, diversity and species richness of Pulau Pangkor, Perak, Malaysia
No full textIslands have attracted great enthusiasm for biogeographers, evolutionary biologists and ecologists as they are good testing grounds for various biological hypotheses. The objective of this study was to assess the beetle diversity and abundance of Pulau Pangkor forest reserves. Beetles were collected using 12 light traps for 4 hours at night, 24 hours collection daily using 100 pitfall traps and 12 Malaise traps for a duration of six days from 15th to 21st July 2017. A total of 277 beetle specimens comprising of 116 species from 26 families were collected, where 75.21% of the collections were singletones. Shannon-Weaver Index showed a value of 3.847 whereas, Fisher alpha diversity index and Simpson Diversity index showed 72.45 and 0.948, respectively. Margalef index for abundance showed a value of 20.09, while the estimated species richness based on Chao 1 showed 347.80. The most abundant family is Bostrichidae accounting for 86 specimens from 20 different species followed by Carabidae with 57 specimens from 10 species. The Cyclosomus sp. (Family Carabidae) collected is reported to be a new species to be described later. Species accumulation curve doesn’t reach the asymptote which is generally observed in the tropics due to the high specious nature. This study shows the beetle diversity at Pulau Pangkor is unique and it requires conservation of habitats. This study can be extended to annual beetle diversity pattern to assess the hypothesis related to biomass reduction, anthropogenic disturbances and island biogeography. © 2019 Forestry Department of Peninsular Malaysia. All Rights Reserved
Interfacial behavior between normal substrate and green ultra‐high‐performance fiber‐reinforced concrete under elevated temperatures
No full textThis study assesses the effects of elevated temperatures (100, 200, 300, 400, and 500°C) on the bonding behavior of normal concrete (NC) substrate as old concrete and the new Green Universiti Sains Malaysia Reinforced Concrete (GUSMRC) as a repair material through slant shear, pull-off, splitting tensile, and flexural tests. Sandblasting (SB) and grinding (GR) surface treatments were employed to enhance the bond strength of the NC/GUSMRC composite. The research also evaluates the mechanical characteristics of the GUSMRC mix which 50% of its content is ultrafine palm oil fuel ash prior to and after the exposure to elevated temperatures. The results showed degradation in the mechanical properties of the monolithic GUSMRC and the bonding strength of the NC/GUSMRC composite after exposure to elevated temperatures; however, the bonding quality is excellent. Moreover, the SB surface treatment enhanced the interfacial bonding more than the GR surface treatment before and after elevated temperature exposure. © 2019 fib. International Federation for Structural Concret
An assessment of the solar photovoltaic generation yield in Malaysia using satellite derived datasets
No full textPrecise and reliable estimation of energy yield for solar photovoltaic (PV) system is imperative for the accurate design of PV system components and power system planning studies with high penetration of renewables. A number of studies have conducted related to PV yield assessments in Europe and some parts of Asia. However, PV yield assessment for various locations in Malaysia is yet to be conducted. This work assesses the average annual PV yield (kWh/kWp/y) in Malaysia for the installed capacity in 2015. Meteorological data from Photovoltaic Geographic Information System (PVGIS) is utilized for yield evaluation. The comparative yield estimation based on PVGIS and yearlong-recorded data for installed PV system at the University of Malaya is conducted first. A little error is observed between the field measurements and the yield studies based on PVGIS data. Then, the expected average yield for the individual region in Malaysia is estimated from PVGIS. Finally, based on the obtained results the individual region in Malaysia is ranked for PV availability. This study could provide very useful information to the power utilities, PV industries, and policymakers regarding the planning of large-scale PV plant, network operation, and future PV system development in Malaysia. © 2019 Regional Energy Resources Information Center (RERIC). All rights reserved
Low-cost, biodegradable and highly effective adsorbents for batch and column fixed bed adsorption processes of methylene blue
No full textThis work reports the preparation of low-cost and ecological bioadsorbents and study of their adsorption properties in the elimination of methylene blue dye (MB) from wastewater Unmodified citrus peels (UCP) and unmodified citrus peels encapsulated with calcium alginate (UCP/A) were characterized by elementary analysis, FTIR, DRX, SEM. Isotherm studies in the batch system were investigated and the maximum adsorbed amounts were found to be 185.83 and 964.54 mg/g respectively for UCP and UCP/A. The Langmuir model fitted well experimental data of isotherms with high coefficient correlation R2, low RMSE and χ2. Fixed bed adsorption was studied with operational conditions such as the bed height, MB flow rate and MB inlet concentration to test the performance of column. The breakthrough curves and the break time increase with the decrease of the rate flow and with the increased bed height. The highest bed capacity of 31.45 mg/g and highest percentage of MB solution treated (93.6%) was obtained using 2 mL/min rate flow, 200 mg/L inlet MB concentration and 3.5 cm (4 g) bed height. The breakthrough curves were fitted using Thomas and Yoon and Nelson models. The behaviors of the breakthrough and the R2 founded by these models are high (R2>0.97) which shows good applicability of models. © 2019 Elsevier Ltd
Climate change adaptation: a corrective policy framework in the Malaysian agricultural sector
No full textA corrective policy framework is essential for sustainable agricultural management. In order to put in place a corrective policy framework, it is necessary to know the socio-economic context of local farmers and their perception of climate change. Therefore, the main objective of this study is to explore their socio-economic status and general perception of climate change and to examine its impact on adaptation practices. To achieve the research objectives, data were collected using survey questionnaires and analysed using statistical tools. The results show that most of the respondents are between the age of 31-45 years in the sample size, 45% has secondary education and 34% of the respondents' monthly income is between RM2,000-RM4,000. It has been found that approximately 76% of farmers had heard about climate change. The results also revealed that socio-economic characteristics such as education, income, type of farmer, attitudes and awareness were positive and highly significant. It is hoped that the findings of this study would be useful for policymakers in designing an appropriate policy framework to raise awareness of how to reduce the impact of climate change in the agricultural sector. Copyright © 2019 Inderscience Enterprises Ltd
Maritime journeys of European opera in the Indonesian archipelago, 1835–1869
No full textProfessional performers of European opera began to arrive in Batavia in the 1830s. More performers set foot in Batavia in the next three decades and presented the often-matching selections of Italian and French opera. By the end of the 1860s the touring circuit of the itinerant performers encompassed leading port cities and towns, including Semarang, Surabaya and Padang. This article argues the coming of professional European opera to the Indonesian archipelago and greater maritime Asia was connected to the nineteenth-century operatic expansion in which the middling and intrepid singers transmitted current works of European opera to frontier regions. The journeys of the operatic pioneers to and from the Indonesian archipelago also mirrored an ongoing structural shift in coastal shipping from a business dominated by British merchant fleets to one serviced by the private firms under the contract of the Dutch East Indies government. © The Author(s) 2019
Two-step catalytic reactive extraction and transesterification process via ultrasonic irradiation for biodiesel production from solid Jatropha oil seeds
No full textA two-step catalytic reactive extraction and transesterification process was adopted to synthesize biodiesel from solid Jatropha seeds, a non-edible source with high free acid content, directly using ultrasound irradiation. From the intensification of reactive extraction process coupled with ultrasound, esterified oil with satisfactory extraction efficiency of 84.0 ± 0.5%, FAME purity of 38.6 ± 1.3% and esterification efficiency of 71.1 ± 1.3% were obtained. High acid value (AV) of 18.2 ± 0.5 mg KOH/g was successfully reduced to 5.3 ± 0.2 mg KOH/g. In the subsequent transesterification of esterified Jatropha oil, FAME purity of 99.0 ± 1.3% and biodiesel yield of 85.2 ± 1.3% were attained at KOH loading of 1.5 wt.%, methanol to oil molar ratio of 12:1 and ultrasonic amplitude of 60% after 15 min reaction time. From the artificial neural network (ANN) modelling, coefficient of determination (R2) for FAME purity and biodiesel yield were found to be 0.9926 and 0.9845, respectively, which proved that the model had good fit with the experimental data. Under the same optimized reaction conditions, this process intensification could achieve higher FAME purity (99.0% vs. 91.8%), biodiesel yield (85.2% vs. 75.6%) and AV reduction efficiency (88.5% vs. 88.2%) than conventional magnetic stirring. © 2019 Elsevier B.V