Circuit for early lightning warning alarm system

Lightning is among the most deadly natural phenomena to mankind. This phenomenon is seen to increase globally as well as in Malaysia. Lightning does strike open areas such as playing fields and playgrounds and these areas are places people gather. Sensors that can detect the early occurrence of lightning have been developed for detecting approaching lightning activity in this project. The main objective is to provide early lightning warning system to the public and hence to reduce the number of fatalities due to lightning strike. The warning circuit was designed and simulated using Multism11. Basic operational method of the circuit is based on the comparative voltage method using LM339N integrated circuit comparator (IC). Light Emitting Diodes (LEDs) were used as indicators to indicate if the incoming voltage level is higher or lower than that of the safety level

Comparative study on preliminary breakdown pulse trains observed in Johor, Malaysia and Florida, USA

In this paper, the preliminary breakdown (PB) pulse train preceding the negative first return stroke (RS) is recorded using a broad band antenna system. These analyses were carried out in Johor Bahru, Malaysia and Florida, United States. This is a novel initiative at examining and identifying the characteristics of the PB pulse trains in the negative cloud-to-ground flashes observed in Malaysia. The arithmetic mean of the total pulse train duration is 12.3 ms and the weighted arithmetic mean of the pulse durations and interpulse intervals are 11 s and 152 s, respectively. The arithmetic mean ratio between the maximum peak amplitude of the PB pulse and the peak RS electric field was 27.8%, and the corresponding value in Florida was 29.4%. The arithmetic mean of the time duration between the most active part of the pulse train, and the RS was 57.6 ms in Malaysia and 22 ms in Florida. A qualitative comparison of our results with those obtained earlier in Sri Lanka, Sweden and Finland supports the hypothesis that the PBP/RS ratio is higher in the northern regions compared to the tropical regions

Effect of Humidity on Partial Discharge Characteristics of Epoxy/Boron Nitride Nanocomposite under High Voltage Stress

Partial discharge (PD) may lead to the degradation of insulating materials and affect the lifetime of high voltage equipment. This paper describes the effect of relative humidity on PD characteristic of epoxy/boron nitride (BN) nanocomposite under high voltage (HV) stress. In this work, CIGRE Method II was utilized as an electrode configuration. BN nanofiller was chosen because of its high insulating properties with high thermal conductivity. The PD characteristics such as PD charge magnitude, PD number or occurrence, and average of PD charge during certain of ageing time under HV stress against relative humidity were examined. The results revealed that PD number of humid samples is higher about 8~14% compared to the normal ones. It is considered due to the decrease of surface resistance of the humid samples. The PD charge magnitudes of humid samples are slightly higher compared to the normal ones. The epoxy/BN nanocomposite has lesser PD number and magnitude compared to the neat epoxy samples

The Almanac of AMG UMP YASA Programme 2021 2022

t is said that learning a new language opens a whole new world of opportunities, and the Akademi Menara Gading Universiti Malaysia Pahang Yayasan Al-Sultan Abdullah Programme (AMG UMP YASA) 2021-2022 is a perfect reflection of that ideal

Measurement of Dielectric Properties of Low-Density Polyethylene Nanocomposites Using “Sub-Hertz” Dielectric Spectroscopy

Recently, many studies have been conducted on the dielectric properties of Low-Density Polyethylene (LDPE) nanocomposites and produced different results. However, the composition of LDPE polymer and boron nitride (BN) as nanofiller has neither been well understood nor producing a convenient result. Similarly, the dielectric spectroscopy measured at “sub–hertz” frequency has been of little interest among researchers since it is often influenced by “conduction-like” effect. This research identified the dielectric properties of LDPE nanocomposites filled with hexagonal boron nitride (h-BN) nanofillers by using dielectric spectroscopy technique. The dielectric loss and relative permittivity for three different filler concentrations were investigated under “sub-hertz” frequency ranges at room temperature. The cylindrical electrode with guard ring configuration was used to conduct the experiment, in accordance to the ASTM D150 standard. The results revealed that 5 wt% filled polymer has lower loss tangent and permittivity compared to the unfilled polymer, due to the strong interaction between nano-particle and the polymer. This strong interaction is believed to limit the movement of the polymer chain. The decrease in loss tangent also indicates lower quasi-DC at low frequency. However, further increase in the filler loading has recorded an increment in the value of permittivity and loss tangent. This higher effective permittivity is mainly due to the influence of the filler permittivity

Thunderstorm Prediction Model Using SMOTE Sampling and Machine Learning Approach

Thunderstorms are one of the most destructive phenomena worldwide and are primarily associated with lightning and heavy rain that cause human fatalities, urban floods, and crop damage. Therefore, predicting thunderstorms with reasonable accuracy is one of the crucial requirements for the planning and management of many applications, including agriculture, flood control, and air traffic control. This study extensively applied the historical lightning and meteorological data from 2011 to 2018 of the southern regions of Peninsular Malaysia to predict thunderstorm occurrence. Positive CG lightning rarely occurs compared to negative CG lightning and also due to the non-linear and complex characteristics of the thunderstorm and lightning itself, leading to an imbalance in the dataset. The resampling technique called SMOTE is introduced to overcome the imbalance of the training dataset. Then the dataset is trained and tested with five Machine Learning (ML) algorithms, including Decision Trees (DT), Adaptive Boosting (AdaBoost), Random Forest (RF), Extra Trees (ET), and Gradient Boosting (GB). The results have shown a good prediction with accuracy (74% to 95%), recall (72% to 93%), precision (76% to 97%), and F1-Score (74% to 95%) with SMOTE. The SMOTE and GB model prediction model is the best algorithm for thunderstorm prediction for this region in terms of performance metrics. In the future, the prediction results based on the lightning pattern and weather dataset will likely alert the related authorities to make an early strategy to handle the occurrence of thunderstorms

The Almost Forgotten Library: Revisiting Toxic Sources

The modern library is an almost forgotten species. With the Internet, new technologies and social media, the library has changed to being an information resource repository of the world. The World Wide Web has thus become the library. But what does that mean? How does that factor in universal versus local knowledge? How does that facilitate us in terms of domination and empowerment? This paper looks at the need for revisiting the library and a sense of reconciliation with the past by non-Western societies. If the whole world is the library, which world are we or should we be most concerned with

Word sense disambiguation for English Quranic IR system

Quranic text Information Retrieval (IR) is quite demanding yet very trivial due to that user will not always use the exact keywords to retrieve the relevant Quranic text (verse). Many have tried to overcome this problem by expanding or reformulating the query entered by users using semantic approaches with resources such as ontologies and thesauri. Word Sense Disambiguation (WSD) has been less interest to the IR research community due to the insignificant or very little significant impact on the IR performance. Recently, researchers pay interest on applying WSD to the IR problem due to the intuition that deep semantic analysis on the query process will give good impact on the IR performance. However, we have not seen any articles mentioning the use of WSD for Quranic IR, which we are assuming less or none research on WSD for Quranic IR have been carried out. Thus, this motivates us to explore WSD impact on Quranic IR performance. This paper will describe our on-going project on building an English Quranic WSD at the early stage, which is still at the proposal stage, where we layout what could be the best approach, resources and disambiguation algorithm for Quranic WSD for IR

Experimental Investigation on Vegetative Oils under Accelerated Thermal Ageing against Their Dielectric Strength

Insulation is one of the most important parts in high voltage apparatus such as power transformer. Most power transformer use liquid insulation material, known as power transformer oil. Petroleum-based oil so called mineral oil has been used for many years as power transformer oil. This is due to its high dielectric field strength, low dielectric loses and good long-term performance. This research work has been carried out to investigate the effect of thermal accelerated ageing on electrical properties for several vegetative-based oils. The oil samples that have been used in this research work are soy bean-based oil (FR3) and commercial palm-based oil (PFAE). As comparison, Hyrax mineral oil has also been investigated. The results revealed that vegetative-based oils have as well as dielectric strength compared with mineral oil.  It was found that the dielectric strength for all oil samples decreased when undergo the thermal accelerated ageing process