Thelaha Masri - Academia.edu (original) (raw)

Papers by Thelaha Masri

ARCHIVE: Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 1994-1996 (vols 208-210), 1995

The friction and wear behaviour of four structural ceramics (two aluminium oxides of different pu... more The friction and wear behaviour of four structural ceramics (two aluminium oxides of different purity, a silicon nitride and a tetragonal zirconia polycrystal) have been investigated under boundary lubrication against a 100C6 hard steel (52100 steel). The effect of three initial surface roughnesses of the ceramics is studied. Lubrication is by a commercial oil used ‘as received’ (new oil) and ‘aged’ (used oil). Tests are performed on an alternating ‘pin-on-plate’ tribometer. The friction and wear responses are analysed in terms of three main parameters depending on the mechanical preparation mode of the ceramics surface: the roughness magnitude, the morphology of the asperities (sharps or blunts) and the mechanical strength of the asperities. The evolution of these parameters during sliding leads to significant changes of tribological behaviour and contact pressure. The friction and wear transitions result from changes of the lubrication mode where roughness and oil have a competiti...

Communications in Soil Science and Plant Analysis, 2011

... 200610. Darwish, T., Khawlie, M., Jomaa, I., Abou Daher, M., Awad, M., Masri, T., Shaban, A.,... more ... 200610. Darwish, T., Khawlie, M., Jomaa, I., Abou Daher, M., Awad, M., Masri, T., Shaban, A., Faour, G., Bou Kheir, R., Abdallah, C. and Haddad, T. 2006. ... Nitrate was determined colorimetrically with the chromotropic acid method (Ryan et al. 199629. ...

Mobile Satellite (MS) Signal performance is affected by many factors such as ionospheric effect, ... more Mobile Satellite (MS) Signal performance is affected by many factors such as ionospheric effect, multipath fading tree-shadowed and buildingshadowed. These cause variations in the received signal quality. Although many studies have been carried out in order to improve the performance of MS signal, there are still many areas lacking data especially from the less-developed and developing countries. Furthermore, costly data acquisition method hinders more study to be carried out in these regions. This paper discusses the cost effective alternative method for MS data acquisition for satellite operating in the L-band by utilizing the GPS satellites data. Details methodology for doing the experimental works will be discussed. The measurements of the signal performance are performed for open space environment in Sarawak. The analysis of the signal performance under different MS environments is performed with respect to the information such as elevation and azimuth angles. The analysis prod...

Electricity is the basic need of everyone in urban and rural areas. In Sarawak, most of the rural... more Electricity is the basic need of everyone in urban and rural areas. In Sarawak, most of the rural dweller depends on diesel generator for electrical power. However, there are problems such as high cost of fossil fuel, transportation and stepping down of 33/132 kV transmission lines that pass through the areas, to overcome the aforementioned problems. Wind energy provides an alternative to the current dependency on fossil fuel. This paper presents a suitable conceptual framework of wind characteristics and energy potential modeling for rural electrification in Sarawak. The proposed concept consist of six (6) different subsystem namely; topographic, wind data collection and processing, development of numerical wind prediction model, wind speed variation and energy potentials modeling analysis, Micrositing model development and GIS model-based wind mapping

The Under-Frequency Load Shedding (UFLS) scheme has been used by power utility companies around t... more The Under-Frequency Load Shedding (UFLS) scheme has been used by power utility companies around the world to mitigate frequency drop caused by simultaneous or cascading tripping of transmission lines and/or generators in a power system. There are many factors that will affect how a UFLS scheme will respond in the event of a system contingency. This paper reviews researches done on UFLS design and applications for industrial customers, interconnected power systems and power systems with distributed generations and pumped storages connected.

Journal of Cleaner Production, 2017

Nigerian Journal of Technology, 2015

2nd European Conference on Antennas and Propagation (EuCAP 2007), 2007

... FOR WLAN APPLICATIONS &amp;amp;amp;amp;#x27;S .Z. Ibrahim &amp;amp;amp;amp;#x... more ... FOR WLAN APPLICATIONS &amp;amp;amp;amp;#x27;S .Z. Ibrahim &amp;amp;amp;amp;#x27;MKARahim, &amp;amp;amp;amp;#x27;TMasri, &amp;amp;amp;amp;#x27;MNAKarim, 2M.ZAAbdulAziz &amp;amp;amp;amp;#x27;Wireless Communication Centre, Faculty of Electrical Engineering, Universiti Teknologi Malaysia, 81310 Skudai Johore Baharu. ...

2006 International RF and Microwave Conference, 2006

2013 IEEE 4th Control and System Graduate Research Colloquium, 2013

The Under-frequency Load Shedding (UFLS) scheme has been used by utility companies around the wor... more The Under-frequency Load Shedding (UFLS) scheme has been used by utility companies around the world to mitigate frequency drop caused by simultaneous or cascading tripping of transmission lines and/or generators in a power system. In the effort to devise an optimal load shedding scheme, it is imperative that investigations are done on the many factors that may affect the response of the scheme in the event of a system contingency. This paper starts by analysing the implementation of UFLS in various power utility companies in Asia, Europe, Australasia, South Africa, Middle East and the Americas. It is observed that UFLS in these continents differ in terms of total load shed, number of UFLS blocks, average block size and trip frequency deviation thresholds depending on their system size, system inertia and generation mix. This paper also looked at the usage of System Frequency Response (SFR) models in the computation of UFLS and system parameters. Analysis on the SFR model showed that...

Satellite signals for communication and navigation experience impairment effects due to ionospher... more Satellite signals for communication and navigation experience impairment effects due to ionosphere especially in the equatorial region. The causes and significance of ionosphere disturbances are a kind of research that is of great interest in this area. Space-based radio communication systems such as the Global Positioning System (GPS) is providing a unique chance to explore the impact of the ionosphere as the signals propagate from the satellites to the GPS receivers. Sarawak which is located near to the equatorial region has been selected for the aim of this research. By utilizing the Total Electron Content (TEC), data recorded by the GPS Ionospheric Scintillation & TEC Monitor (GISTM), the ionospheric effect was examined and related to the signal strength performance. The recorded TEC were tested by comparing to TEC obtained from CODE Global Ionosphere Maps (GIMs) in time series. The results have shown a high consistency of TEC in the time domain with their corresponding minimum ...

Journal of Telecommunication, Electronic and Computer Engineering, 2018

In this paper, the design of a high gain modified antipodal Vivaldi antenna (HG-MAVA) for ultra-w... more In this paper, the design of a high gain modified antipodal Vivaldi antenna (HG-MAVA) for ultra-wideband applications is presented. The proposed antenna designed on a low-cost FR4 substrate with a thickness of 1.6mm was realized by incorporating a combination of exponential slot edge corrugation on the radiating flare and a high permittivity dielectric director in the flare aperture of a conventional antipodal Vivaldi antenna (CAVA). Compared to the CAVA, the proposed antenna extends the lower end frequency limit of the CAVA to 2.15 GHz. Improvement in realized gain is also achieved throughout the 2.15 GHz to more than 11 GHz operating frequency band of the proposed antenna with the highest improvement of 1.61 dBi at 7 GHz. The surface current distribution and the radiation pattern of the proposed antenna were studied to further characterize the performance of the antenna.