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Articles by A. Shafie
Total Records ( 6 ) for A. Shafie
  S.S. Mokri , H. Husain , W. Martono and A. Shafie
  Nonlinearities and parametric uncertainties are unavoidable problems faced in controlling robot manipulator. A single link manipulator driven by a permanent magnet brushed dc motor is a nonlinear dynamics due to effects of gravitational force, mass of the payload, posture of the manipulator and viscous friction coefficient. Furthermore, uncertainties arise because of changes of the rotor resistance with temperature and random variation of friction while operating. Due to this fact, classical PID controller can not be used effectively since it is developed based on linear system theory. In order to overcome this problem, in this research, a neural network control scheme, NARMA-L2 Control is adopted and implemented in real time for controlling a DC motor driven single link manipulator with unknown dynamics. However, the real time experimentation showed that the proposed system results in chattering of the control signal. Hence, the system also chatters within the desired trajectory. As a solution, real time Smoothed NARMA-L2 Control scheme is implemented. Physical results showed that the improved control scheme has not only reduced the chattering but has successfully controlled the single link manipulator for both point-to-point and continuous path motion control.
  A. Shafie and M.A.B. Abdelaziz
  Photovoltaic is a technology in which solar radiation is converted to electrical power, that is, direct current. The use of photovoltaic as power source for water pumping activities is one of the promising areas in photovoltaic application. The objective of this study is to develop a software that can be used as guidelines for developing suitable photovoltaic based irrigation system. This study presents the design and the technical requirements of a photovoltaic powered water pumping system for irrigation. The design of the photovoltaic system is based on the estimation of the water requirement, pumping system selection and sizing, photovoltaic arrays sizing, load matching design, along with the meteorological data of the site location. Java language was employed in the development of the software.
  M.N. Akhtar , N. Yahya , H. Daud , A. Shafie , H.M. Zaid , M. Kashif and N. Nasir
  Seabed logging is a new technology being implemented for deep target exploration. The technology uses electromagnetic (EM) wave where an antenna transmits EM wave into water layer underneath seabed and with resistivity characteristics of hydrocarbon reservoir, the wave is reflected and received by the detectors on the seafloor. However, the roughness of the sea caused by underwater sea current limits the transmission of EM wave. EM wave itself has its own attenuation in seawater that is 102 dBm and the underwater sea current has made it worst. In seabed logging technology, the vessel is towing the transmitter at a very slow speed (1.5 km h-1) with high EM wave energy for transmitting the waves of ~1250 A cm-2. Due to this large current more heat is generated. In this project, we propose an EM wave guide amplifier to be used to overcome these problems. The EM wave guide amplifier amplifies the wave without modifying the transmitter (antenna) circuit. Therefore lower energy is required for the transmitter and is sufficient for seabed logging technology. The thermionic cathode and molybdenum (Mo) anode with work function of 1 eV are selected to get higher amplification of EM wave. It is found that potential difference between the cathode and anode improves the electron acceleration in the wave guide amplifier. It has been observed that with the use of wave guide amplifier and with 20 Vpp supply to the transmitter at 5 MHz frequency, the wave received by receiver has been amplified up to 170%. The application of this new method in seabed logging shall reduce the heat generated and overcome the EM wave attenuation problems.
  N. Nasir , N. Yahya , M.N. Akhtar , M. Kashif , A. Shafie , H. Daud and H.M. Zaid
  Seabed Logging (SBL) is new technique to detect hydrocarbon reservoir under the sea bed. EM transmitter is used to transmit low frequency electromagnetic signals into the subsurface layers of the sea bed to detect different resistive layers. However, detection of resistivity contrast in different resistive layers for a deep target is still a challenge in SBL. Due to economical point of view a scaled tank with a scale factor of 2000 was built to study the resistivity contrast. In the scale tank experiment aluminium rod EM transmitter of length 50 cm is towed at 35 cm height from the bottom of the tank. Three receivers are placed at 25 cm from the bottom of the tank. A series of experiments were conducted with different resistive mediums such as (tap water, salt water and salt water with oil packets). The oil packets were placed at certain positions in the water tank. The electromagnetic field responses from different resistive layers were recorded by the receivers. Different response in the magnitude of magnetic field was observed by different resistive medium. It was also observed that the magnetic field strength had increased 50% for salt water and 150% for oil which clearly shows the resistivity contrast. Our preliminary results have shown that high resistive layers in a conductive medium can be detected by using the experimental set up.
  M. Kashif , N. Yahya , H.M. Zaid , A. Shafie , M. Jasamai , N. Nasir and M.N. Akhter
  This study describes electromagnetic heating of oil using curve transmitter with magnetic feeders in the radio frequency region. The transmitter was developed to focus the electromagnetic waves to the target. A series of experiments were done to find focus point of electromagnetic waves by using curve transmitter with magnetic feeders in water tank filled with brine at 15% salinity. The center of the transmitter has 184.4% higher magnetic field strength as compared to both end of the transmitter. Three magnetic feeders had resulted approximately 210% increased of magnetic field. The porosity and permeability of the core samples were also measured. Oil saturated core rock samples were kept in tank filled with brine of 15% salinity for efficient oil recovery. The EM waves emitted by the curve transmitter with 3 magnetic feeders were able to recover 43.71 (sample 1) and 59.26% of OIP (sample 2).
  H.M. Zaid , N.B. Yahya , M.N. Akhtar , M. Kashif , H. Daud , S. Brahim , A. Shafie , N.H.H.M. Hanif and A.A.B. Zorkepli
  Controlled Source Electromagnetic (CSEM) is a new technique used for hydrocarbons detection. This study focuses on One dimension (1D) modeling of hydrocarbon detection for onshore application using the principles of electromagnetic (EM) waves propagation. The transmitted frequency which is 0.25 Hz was used to characterize the hydrocarbon at 500 m, 1000 m and 1500 m. Electric fields detected by the receivers at 500, 1000 and 1500 m were 22.85, 20.4 and 17.1 V m-1, respectively which was determined by using 1D simulation. This non-seismic 1D modeling may provide alternative solution for hydrocarbon (HC) detection for oil and gas industry.
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