Vol. 3, Issue 2 (2020)

Journal of Defence Science, Engineering & Technology

APPLICATION OF ULTRA-HIGH FREQUENCY ANTENNA FOR PARTIAL DISCHARGE DETECTION IN OIL-FILLED POWER TRANSFORMER: A REVIEW

Azharudin Mukhtaruddin, Muzamir Isa, Mohd Fadzil Ain, Mazlee Mohd Noor, Mohd Rafi Adzman, Mohamad Nur Khairul Hafizi Rohani

 

Abstract

Partial discharge (PD) is a phenomenon that may lead to dielectric breakdown and can provide important information for condition monitoring on electrical power equipment, in particular transformer. One of the methods is the detection of the electromagnetic (EM) wave signal emitted by PD. Although the frequency spectrum in EM is very wide, this paper discusses the detection of EM only at ultra-high frequency (UHF). One of the detectors that can be used to detect EM is the antenna. There are a lot of antenna designs that have been proposed to detect the signal. The designs can be generally divided into two: PCB-based design and physical antenna design. An example of the latter is monopole. Some of the proposed antennas were left at the design stage while others went to be applied in actual PD experimentation. Discussion on the capabilities of these antennas can lead to the selection of a suitable antenna.


PATH FINDING OF STATIC INDOOR MOBILE ROBOT VIA AOR ITERATIVE METHOD USING HARMONIC POTENTIALS

A'qilah Ahmad Dahalan, Azali Saudi, Jumat Sulaiman 

 

Abstract

Mobile robots often have to discover a path of collision-free towards a specific goal point in their environment. We are trying to resolve the mobile robot problem iteratively by means of numerical technique. It is built on a method of potential field that count on the use of Laplace’s equation in the mobile robot’s configuration space to constrain/which reduces the generation of a potential function over regions. This paper proposed an iterative approach in solving robot path finding problem known as Accelerated Over-Relaxation (AOR). The experiment shows that these suggested approach can establish a smooth path between the starting and goal points by engaging with a finite-difference technique. The simulation results also show that a more rapidly solution with smoother path than the previous work is achieved via this numerical approach. 

 

PEMANTAUAN TAHAP HINGAR SEMASA OPERASI PESAWAT SUKHOI DI NO. 11 SKUADRON

Mohd Rizal Hamid, Ahmad Faruq Mohamad Rosli, Kesavan Manokaran, Siti Shafiqa Shamira Hashin, Nik Mohd Dzarrin Ghifari Azmy, Baba Md Deros, Dian Darina Indah Daruis 

 

Abstract

Kesedaran terhadap bunyi bising di tempat kerja sememangnya semakin meningkat. Di pengkalan No. 11 Skuadron serta bangunan bersebelahan dengannya, pesawat Sukhoi merupakan punca utama bunyi bising atau hingar yang memberi kesan kepada pekerja dan orang awam. Objektif kajian ini adalah untuk menentukan kadar bunyi yang dihasilkan oleh pesawat Sukhoi ketika operasi penyelenggaraan. Pesawat Sukhoi mempunyai dua enjin yang merupakan punca bunyi bising di lapangan ini. Kajian ini dijalankan dengan menggunakan alat pengukur bunyi mudah alih Bruel & Kjaer 2250 yang diletakkan di tengah-tengah pesawat di dalam hangar untuk mengukur bunyi pada jarak 10 meter, 50 meter, 100 meter, 500 meter, 1000 meter dan 1500 meter. Enjin pesawat tersebut beroperasi pada dua tahap, 72% RPM dan kemudiannya pada 85% RPM. Pada setiap jarak, golongan yang terdedah berbeza di mana orang awam hanya terlibat bermula dari jarak 1000 meter dan ke atas. Pekerja TUDM dan pekerja yang terlibat dengan penyelenggaraan pesawat tersebut terdedah dengan bunyi bermula dari jarak 0 meter lagi (yakni berada dibawah enjin pesawat). Data yang diperoleh dianalisa untuk menghasilkan peta hingar dan kontur hingar. Hasil daripada lakaran tersebut, tahap pendedahan hingar dapat dikenalpasti. Bunyi maksima yang telah direkodkan adalah 122 db(A) manakala yang terendah adalah 60 dB(A). Kadar bunyi yang direkodkan semakin rendah apabila jarak dari punca bunyi bertambah. Dari peta lakaran tersebut, kesan pendedahan terhadap kedua-dua pekerja dan orang awam dapat dikenalpasti. Walaupun pendedahan selama 5-10 minit sahaja setiap kali ia berlaku, tetapi ia tetap menjengkelkan (annoyance) dan untuk jangka masa panjang ia tetap dapat mengancam kesihatan mereka yang terlibat.

 

 Awareness of occupational noise and its effects is growing. At No. 11 squadron base, Sukhoi jet was identified as the main culprit of occupational noise that affects not just the employees of the base but also civilian people in the surrounding area. The objective of the study is to identify the noise level produced by Sukhoi two-engines jet during maintenance operations. Investigations were carried out using Bruel & Kjaer 2250 sound level meter hand-analyser. Measurements were performed directly under the Sukhoi jet body and then 10 metres, 50 metres, 100 metres, 1000 metres and 1500 metres away. The jet engines could operate at two levels, at 72% RPM and at 85% RPM. The civilians are only exposed to its noise from more than 1000 metres away. The results from this study are analysed and noise mapping and noise contouring are produced which give the level of noise exposure. The maximum noise is recorded t 122dB(A) and the minimum is at 60dB(A). The farther the noise from the jet is measured, the lower the values recorded. From the noise mapping, the effects of noise exposures on both the employees at the base and the civilian at the neighbouring surrounding could be identified. Even though the exposures are only for 5-10 minutes, it is still considered as a threat. 

 

A REVIEW ON TECHNIQUES AND CHALLENGES IN SENTIMENT ANALYSIS OF STUDENT’S COMMENTS

Siti Rohaidah Ahmad, Nurhafizah Moziyana Mohd Yusof, Siti Hajar Zainal Rashid, Abdul Ghapor Hussin 

 

Abstract

Assessment of instructors by students is needed for assessing the teaching quality of a lecturer towards achieving the objectives of a course. This paper aims to examine the techniques used in sentiment analysis for assessing the effectiveness of a lecturer’s or a teacher’s teaching style in the learning process at a university or school. In addition, the effectiveness of sentiment analysis techniques in assisting the teaching evaluation process is also discussed. The challenges for assessing the quality of teaching of National Defence University of Malaysia (UPNM) lecturers are also discussed in this paper. The sentiment analysis technology is capable of analysing views or opinions on a matter, regardless of whether they are positive or negative. Data from the sentiment analysis can be used by specific parties or anyone else to rectify any weakness or to improve any aspect that the user commented on. The purpose of this study is not to find the weakness of the lecturer, but rather the results of this assessment process can be useful to the management for rectifying weaknesses and for improving the teaching process. 

 

THE RESPONSE OF HYPOXIA BIOMARKERS TO HYPERBARIC OXYGEN THERAPY IN PREVENTING HYPOXIA AT HIGH ALTITUDE

Shazreen Shaharuddin, Fathinul Fikri Ahmad Saad, Aminuddin Abdul Hamid Karim 

 

Abstract

Training at high altitude for prolonged periods can cause low oxygen tension which can developed complication of hypoxia. Hypoxia is a cascade activity from a level of down regulation and function of cell’s nucleus. Early detection of biomarker and physiological changes are important in prevent the hypoxia at high altitude. Hyperbaric medicine is a new treatment that were used an oxygen therapy to treat hypoxic and inflammatory driven conditions which patients are treated with 100% oxygen at pressure greater than atmospheric pressure. The review discusses physiological changes associated with hypoxia, the response of biomarker hypoxia changes in high altitude and the role of hyperbaric oxygen therapy can play as part of the treatment for pilots and athletes training at high altitudes that suffering from disease with underlying hypoxia. 

 

ISSN: 2773-5281