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Articles by M. Othman
Total Records ( 9 ) for M. Othman
  M. K. Hasan , J. Sulaiman , S. Ahmad , M. Othman and S. A.A. Karim
  Problem statement: Development of mathematical models based on set of observed data plays a crucial role to describe and predict any phenomena in science, engineering and economics. Therefore, the main purpose of this study was to compare the efficiency of Arithmetic Mean (AM), Geometric Mean (GM) and Explicit Group (EG) iterative methods to solve system of linear equations via estimation of unknown parameters in linear models. Approach: The system of linear equations for linear models generated by using least square method based on (m+1) set of observed data for number of Gauss-Seidel iteration from various grid sizes. Actually there were two types of linear models considered such as piece-wise linear polynomial and piece-wise Redlich-Kister polynomial. All unknown parameters of these models estimated and calculated by using three proposed iterative methods. Results: Thorough several implementations of numerical experiments, the accuracy for formulations of two proposed models had shown that the use of the third-order Redlich-Kister polynomial has high accuracy compared to linear polynomial case. Conclusion: The efficiency of AM and GM iterative methods based on the Redlich-Kister polynomial is superior as compared to EG iterative method.
  M.S. Bhuyan , B.Y. Majlis , M. Othman , Sawal H. Md Ali , C. Kalaivani and Shabiul Islam
  Dependency on battery as the only power source is putting an enormous burden in many applications due to size, weight, safety and lifetime constraints etc. Emerging applications like wireless sensor networks, implantable medical devices, heating ventilation and air conditioning system for indoor and automotive environmental comfort are examples of such class. In addition, it is often impractical to operate these systems using battery owing to the difficulty in replacing battery. Therefore, the ability to harvest ambient energy is vital for battery less operation. In this study, novel modeling of a micro energy harvester aimed at harvesting energy from fluid-flow induced vibration, through piezoceramic cantilever means is presented. The strategy pursued in order to harvest energy in low fluid-flow conditions, couples vortex shedding from a D-shaped bluff-body to a piezoelectric cantilever attached to the bluff-body. Fluidic pressure impulse on piezoelectric cantilever beam due to vortex shedding results in lift force. Fluctuation of fluidic pressure causes flexible cantilever to vibrate in the direction normal to fluid flow. Deformation of the piezoceramic cantilever converts mechanical energy into electrical energy through its crystalline structure. COMSOL-multiphysics simulations and results are presented in details to demonstrate the feasibility of the harvester in low fluid-flow velocities conditions ranging 1-5 m sec-1. In a (200x150x150) μm3 rectangular duct, at 5 m sec-1 fluid velocity, the (50x40x2) μm3 piezoelectric cantilever experienced concluding statement concluding statement 3088 Pa stress. The resulting cantilever deflection produced 2.9 mv, which is sufficient to drive an ultra-low-power rectifier circuit. This harvester is designed as a useful power source to replace or supplement batteries.
  M. Azaga and M. Othman
  A proposed design of Ultra Wideband (UWB) pulse generator circuit is presented. The design is based on Source Couple Logic (SCL) for its low power and high immune to noise so it can be used in mixed signal ICs environment. The pulse is digitally generated by using SCL inverters and NAND gates; the output of clock pulse input is dual pulse signals opposite to each other. The design is simulated and result of the circuit is dual pulses with width of sub-nanosecond. The results gotten have satisfied the design idea as desired. Post simulation has been carried out by using HSPICE, the layout is done using Cadence Virtuoso and verification is done by Mentor Graphic Interactive tool. All simulations are based on MIMOS 0.35 μm process PDK.
  H.M. Jalalian , L.A. Latiff , S.T. Syed Hassan , P. Hanachi and M. Othman
  The present study focuses on the role of information technology in blood safety policies. In order to reach to higher levels of blood safety we have to put our maximum force in the recruitment of safe blood donors via public education. Innovative use of mass media in recruitment of blood donors, especially the youth and those of higher education level and disseminating the basic information about blood donation can be our success key. There is an urgent need to find new ways of recruiting blood donors rather than traditional methods of donor education. Effectiveness of internet based educational intervention in other disciplines of health has already been proven; however, few researches exist concerning internet application for online recruitment of safe blood donors. Finally, internet users` population and blood donors are similar in many aspects of their socio-demographic determinants and it is reasonable to deduce that online education and dissemination of knowledge of safe blood donation can be considered an efficient modus of recruitment of voluntary non-remunerated blood donors.
  M.K. Hasan , J. Sulaiman , S.A.A. Karim and M. Othman
  The objective of this study was to describe numerical methods that apply complexity reduction approach to solve various scientific problems. Due to their low in complexity, their computations are faster than their standard form. Some of the methods have even higher in accuracy compared to their standard methods. In this study, we will describe the development of some of the methods that have been recently used to solve various scientific problems.
  H.N. Jasem , Z.A. Zukarnain , M. Othman and S. Subramaniam
  When using of the Internet increased dramatically; the congestion avoidance problem became even more important. The congestion is usually caused by the multiplexing for packets when the packets are at the bottleneck links. Efficiency and fairness are the important metrics in the performance of congestion avoidance mechanisms. And also all of the researches for the congestion avoidance algorithms, interest about this parameters metrics to evaluate the performance of the algorithms. This research studied the performance of the New-Additive Increase Multiplicative Decrease (AIMD) algorithm as one of the core protocols for the TCP congestion avoidance and control mechanism. In addition, to evaluate the effect of using the AIMD algorithm after its development to measure the efficiency and fairness and find new enhancement results for our approach, which named as the New-AIMD algorithm. The NCTUns simulator is used to obtain the results after implementing the modifications to the mechanism.
  H.A. Fua’ad , S. Shamala , M. Othman and Z. Zuriati
  Problem statement: The lack of uniformity in the choice of simulation platforms for optical WDM networks stands behind the difficulty of developing a common simulation environment. Correlating WDM unidirectional slotted ring network to Discrete Event Simulation (DES) encompassing event definition, time advancing mechanism and scheduler has yet to be developed. Approach: The study focused on the proposed and the development of an event based discrete simulator for the WDM unidirectional slotted ring network to facilitate the reuse of the protocol modules under a common simulation environment. The proposed network architecture implemented for the developed simulator employs a separate wavelength as the control information channel. This control information enabled the nodes to monitor their access to the transmission media. Each node was equipped with a tunable transmitter and fixed receiver for data communication. Access nodes were equipped with a fixed transmitter and fixed receiver for the control information exchange. The developed simulator had derived the use of dividing the wavelength into slots. Nodes used these slots to transmit fixed size packets. Slots can be reused by the access node after receiving packets by the deployment of the spatial reuse scheme, thus enhancing the bandwidth utilization. The developed simulator had derived the set of the parameters, events, performance metrics and other unique WDM simulator elements according to a detailed analysis of the base model. Results: The network delay and packet loss were investigated and compared to a benchmark of the modeled domain. Successful deployment of the developed simulator was proven by the generated results. Conclusion: Extensive performance analysis of WDM unidirectional slotted ring network can be deployed using the developed simulator with low computational overheads. Further enhancements were to extend the developed simulator for bidirectional slotted ring supporting fairness control and considering both uniform and non-uniform traffic.
  M.S. Bhuyan , B.Y. Majlis , M. Othman , Sawal H. Md. Ali and Shabiul Islam
  This study presents multi-physics three-dimensional finite element simulation of a fluid flow based self-excited micro energy harvester. This micro energy harvester is modeled inside a micro fluid channel to convert fluid flow energy into fluid oscillations. Investigations are carried out for the impact of low fluid flow velocity ranging 1-5 m sec-1, associated voltage generation by piezoelectric means and various mechanical analyses to enhance the performance and robust design considerations. The piezoelectric micro cantilever is attached to a D-shaped bluff body. An axial fluid flow and the D-shaped bluff body interaction generate Karman Vortex Street in the wake of the bluff-body. Vortex shedding causes an asymmetry in pressure distribution on the surface of the bluff body which results in time-dependent forces acting on the attached flexible micro cantilever. Due to structural vibrations induced by the uniform and steady fluid flow, periodic strains are generated in the piezoelectric cantilever which converts the strain energy into electrical charge. Finite Element Analysis Software namely COMSOL Multiphysics are used for the Harvester Model and simulation. In a 200x150x150 μm3 rectangular duct, at 5 m sec-1 fluid velocity, the 50x40x2 μm3 piezoelectric cantilever experienced 3088 Pa stress with cantilever tip displacement around 60 μm. A maximum voltage of 2.9 mV was recorded at 5 m sec-1 fluid velocity that is sufficient to drive an ultra-low-power rectifier circuit for a complete energy harvesting system. This study in detail describes the harvester device modeling and finite element analysis in COMSOL. Instead of using ambient parasitic vibration, this Energy Harvester Model directly utilize fluid flow energy to improve harvesting capability. The micro energy harvester self-charging capability makes it possible to develop untethered sensor nodes that do not require any wired connection or battery replacement or supplement batteries. Integration of fluid flow based micro energy harvester device for the autonomous sensor network such as automotive temperature and humidity sensor networks.
  M.S. Bhuyan , Sawal H. Md. Ali , M. Othman , B.Y. Majlis , Shafii A. Wahab and Shabiul Islam
  The study presented in this research targets the modeling and analysis of a 31 transverse mode type piezoelectric cantilever beam for voltage generation by transforming ambient fluid induced vibration energy into usable electrical energy. Piezoelectric materials have the ability to convert mechanical forces into an electric field in response to the application of mechanical stresses or vice versa. This property of the materials has found applications in sensor and actuator technologies and recently in the new field of energy harvesting. A mathematical model for energy harvesting by a piezoelectric cantilever beam device, based on classical beam analysis is presented. The optimization algorithm is implemented in Matlab, based on four physical dimension parameters of the energy harvesting cantilever. The optimal cantilever design from the theoretically derived algorithm determines four physical dimensions parameter to maximize output power. The output power is used to evaluate the performance of the energy harvester. Some interesting aspects that affect the generation of power are discussed. From this analysis, it is found that increasing the frequency of the vibration improve the output power while beyond a certain value further improvement can not be achieved by simply increasing the vibration frequency. Moreover, output power of the energy harvester is found as a function of external resistance. The model predicted anoptimized design with maximizes output power of 0.9 mW at a natural frequency of 200 Hz. Piezoelectric cantilever based energy harvester device can potentially replace the battery that supplies power in microwatt range necessary for operating wireless sensor devices.
 
 
 
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