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Kuala Selangor, Malaysia

Taer E.,National University of Malaysia | Taer E.,University of Riau | Deraman M.,National University of Malaysia | Talib I.A.,National University of Malaysia | And 3 more authors.
Current Applied Physics | Year: 2010

The physical and electrochemical properties of the activated carbon pellet electrodes have been investigated. Activated carbon pellets were prepared from single step carbonization process of pre-carbonized rubber wood sawdust at a temperature of 800 °C that followed with a CO2 activation process at temperature in the range of 700-1000 °C. The BET characterization on the sample found that the surface area of the carbon pellet increased with the increasing of the activation temperature. The optimum value was as high as 683.63 m2 g-1. The electrical conductivity was also found to increase linearly with the increasing of the activation temperature, namely from 0.0075 S cm-1 to 0.0687 S cm-1 for the activation temperature in the range of 700-1000 °C. The cyclic voltammetry characterization of the samples in aqueous solution of 1 M H2SO4 also found that the specific capacitance increased with the increasing of the activation temperature. Typical optimum value was shown by the sample activated at 900 °C with the specific capacitance was as high as 33.74 F g-1 (scan rate 1 mV s-1). The retained ratio was as high as 32.72%. The activated carbon pellet prepared from the rubber wood sawdust may found used in supercapacitor applications. © 2010 Elsevier B.V. All rights reserved. Source

Ismail I.,University Putra Malaysia | Hashim M.,University Putra Malaysia | Matori K.A.,University Putra Malaysia | Alias R.,Telekom Research And Development Sdn Bhd | Hassan J.,University Putra Malaysia
Journal of Superconductivity and Novel Magnetism | Year: 2012

In this paper the effect of sintering temperature on Ni 0.5Zn 0.5Fe 2O 4 is examined closely. The evolution of toward magnetically ordered materials was to be tracked with the parallel evolving microstructure subjected to sintering temperatures in an ascending order. The starting powder of Ni 0.5Zn 0.5Fe 2O 4 was prepared via mechanical alloying and later molded into toroidal samples. After each sintering, we observed the resulting changes in the materials. The XRD data showed a single phase being formed as early as 600∈°C and the peak intensity was increasing with the sintering temperature indicating an increase in the degree of crystallinity. The BH hysteresis loops showed the evolution from paramagnetism to moderate ferromagnetism to strong ferromagnetism with microstructural changes. For lower sintering temperatures, the samples showed paramagnetic behavior dominating the samples. As sintering temperature increased, paramagnetic states decreased and, at 900∈°C, a moderately ferromagnetic state appeared. Sintering at 1000∈°C produced a strongly ferromagnetic state giving a well-formed sigmoid-shape hysteresis loop. © 2011 Springer Science+Business Media, LLC. Source

Phang T.C.,University Putra Malaysia | Mokhtar M.H.,Telekom Research And Development Sdn Bhd | Rokhani F.Z.,University Putra Malaysia
Proceedings - International Symposium on Quality Electronic Design, ISQED | Year: 2016

In this project, a medium access control utilizing the technique of time-division multiple access was developed for the intra-body communication. A prototype of a wearable health tracker was designed based on a commercially available development kit. The prototype consists of a base unit and three sensor nodes to form a single-hop star topology body area network. Each of the sensor nodes can be interfaced with analog or digital type of wearable sensors to measure human physiological data. © 2016 IEEE. Source

Yeoh C.Y.,Telekom Research And Development Sdn Bhd
Proceedings - 2013 Wireless and Optical Communications Conference, WOCC 2013 | Year: 2013

To avoid interference from a detected radar signal, or to reassign mesh station (STA) channels to ensure the connectivity, IEEE 802.11s defines a procedure on how to propagate the channel switch attempt throughout the mesh network, known as mesh Basic Service Set (MBSS) channel switch. Wireless Mesh Network (WMN) that utilizes single-radio nodes with omni-directional and directional antennas is ideally suited for rural area where cost and simplicity take precedence over service quality. However, single-channel single-radio mesh network is easily affected by the interference from its neighborhood, especially from co-located Wi-Fi deployment or other devices operating in the same frequency channel. Thus, the ability to switch to a new channel for self healing is indeed appealing to single-channel single-radio mesh network. The implementation of 802.11s in Linux kernel is available since the year 2007, but the MBSS channel switching has yet to be implemented. This paper describes the MBSS channel switching in details and also discusses our efforts to implement this in the Linux wireless subsystem. Our implementation are verified and evaluated in our experimental testbed. © 2013 IEEE. Source

Ismail I.,University Putra Malaysia | Hashim M.,University Putra Malaysia | Amin Matori K.,University Putra Malaysia | Alias R.,Telekom Research And Development Sdn Bhd | Hassan J.,University Putra Malaysia
Journal of Magnetism and Magnetic Materials | Year: 2012

Possible soaking-time effects on the magnetic and microstructural properties of polycrystalline samples of Ni 0.5Zn 0.5Fe 2O 4 have been studied. Nanosize powder produced by mechanical alloying was sintered at 800 °C with various soaking times. All samples showed the signature peak of Ni 0.5Zn 0.5Fe 2O 4 even with one hour of soaking time. The size distributions show a slow growth of microstructural evolution related to density, porosity and also to the magnetic hysteresis loops. Within these distributions it is observed that the formation of multi-domains is not possible and probably there are the regions of superparamagnetic and single-domain grains. From the permeability studies, it is believed that the rise of the magnetic moment on the B sites give rise to the total saturation magnetization with increase of soaking time. The hysteresis loop of one-hour soaking time showed paramagnetic behavior dominating while longer soaking times showed ferromagnetic behavior starting to dominate. The coercivity was observed to increase with soaking time, signaling the increase of the anisotropy fields which was attributed to the shape anisotropy and also to the magnetocrystalline anisotropy. By correlating the morphology, phase analysis, permeability and hysteresis loops results, it is believed that there was an increase in number of crystalline-growth regions which together formed a total mass of mixed superparamagnetic and ferromagnetic grains with the latter starting to dominate the samples. © 2012 Elsevier B.V. All rights reserved. Source

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