Abdullahi Abubakar Mas'ud

Relay Selection with Limited and Noisy Feedback

Relay selection is a simple technique that achieves spatial diversity in cooperative relay networks. Nonetheless, relay selection algorithms generally require error-free channel state information (CSI) from all cooperating relays. Practically, CSI acquisition generates a great deal of feedback overhead that could result in significant transmission delays. In addition to this, the fed back channel information is usually corrupted by additive noise. This could lead to transmission outages if the central node selects the set of cooperating relays based on inaccurate feedback information. In this paper, we propose a relay selection algorithm that tackles the above challenges. Instead of allocating each relay a dedicated channel for feedback, all relays share a pool of feedback channels. Following that, each relay feeds back its identity only if its effective channel (source-relay-destination) exceeds a threshold. After deriving closed-form expressions for the feedback load and the achievable rate, we show that the proposed algorithm drastically reduces the feedback overhead and achieves a rate close to that obtained by selection algorithms with dedicated error-free feedback from all relays.

Behavior of an Inductive Loop Sensor in the Measurement of Partial Discharge Pulses with Variations in Its Separation from the Primary Conductor

Ideally, an insulation system must be capable of electrically insulating the active components of a machine or device subjected to high voltages. However, due to the presence of polluting agents or imperfections inside or on the surface of the insulation, small current pulses called partial discharges (PDs) are common, which partially short-circuit the insulation and cause it to lose its insulating properties, and thus its insulation capacity, over time. In some cases, measurements of this phenomenon are limited by the type of sensor used; if it is not adequate, it can distort the obtained results, which can lead to a misdiagnosis of the state of the device. The inductive loop sensor has experimentally been demonstrated to be capable of properly measuring different types of PDs. However, because of its current design, there are several practical limitations on its use in real devices or environments. An example is the presence of a primary conductor located at a fixed distance from the sensor, through which PD pulses must flow for the sensor to capture them. In this article, the sensor’s behavior is studied at different separation distances from the line through which the PD pulses flow. In addition, the measuring capacity of the sensor is tested by removing the presence of the primary conductor and placing the sensor directly over the line through which the PD pulses of a real device flow.

Effect of diffuse radiation on the performance of a rotationally asymmetrical optical concentrator

This paper evaluates the performance of a recently patented rotationally asymmetrical dielectric totally internally reflective concentrator (RADTIRC) under diffuse radiation. The RADTIRC has a geometrical concentration gain of 4.969 and two half acceptance angles of ± 30° and ± 40° along the x-axis and z-axis respectively. Simulation and experimental work have been carried out to determine the optical concentration gain under diffuse radiation. It was found that the RADTIRC has an optical concentration gain of 1.94 under diffuse irradiance. The experimental results for the single concentrator showed an optoelectronic gain of 2.13, giving a difference of 9.8% due to factors such as the presence of direct radiation during experiments, the increase in diffuse radiation due to the reflection from surrounded buildings as well as from the ground reflection.

Modelling the Effect of Applied Voltage and Frequency on Electroluminescence in Polymeric Material

N. A. Bani, Z. Abdul-Malek, F. Muhammad-Sukki, A. Abubakar Mas’ud, M. N. Muhtazaruddin, K Kamardin, J. J. Jamian, H. Ahmad Razak School of Engineering and Advanced Technology, Universiti Teknologi Malaysia, Kuala Lumpur, Malaysia Institute of High Voltage and High Current (IVAT), Universiti Teknologi Malaysia, Johor, Malaysia School of Engineering, Faculty of Design and Technology, Robert Gordon University, Aberdeen, United Kingdom Faculty of Engineering, Multimedia University, Persiaran Multimedia, Cyberjaya, Selangor, Malaysia Department of Electrical and Electronic Engineering Technology, Jubail Industrial College, Saudi Arabia Advanced Informatics School, Universiti Teknologi Malaysia, Kuala Lumpur, Malaysia Faculty of Electrical Engineering, Universiti Teknologi Malaysia, Johor, Malaysia Faculty of Electrical and Electronic Engineering, Universiti Tun Hussein Onn Malaysia, Malaysia

Statistical error tolerances of partial discharge recognition rates

This paper compares the statistical error tolerances of the single neural network (SNN) and the ensemble neural network (ENN) recognition efficiencies, when both the SNN and ENN are applied to recognize partial discharge (PD) patterns. Statistical fingerprints from the phased and amplitude resolved patterns of PDs, have been applied for training and testing the SNN and the ENN. Statistical mean and variances of the SNN and ENN recognition rates were compared and evaluated over several iterations in order to obtain an acceptable value. The results show that the ENN is generally more robust and often provides an improved recognition rate with higher mean value and lower variance when compared with the SNN. The result implies that it is possible to determine the accurate statistical error tolerances for the SNN and ENN recognition probability for correct diagnosis of PD fault.

Linear quadratic optimal control of a DC motor

This paper introduces a new way of controlling a DC motor, by applying a linear quadratic optimal control. It includes all the experiments that were carried out in the lab to obtain all the parameters of the motor before modelling the motor into a discrete time state space model. Based on the theory of linear optimal control using algebraic Ricatti equation, a simulation of the motor using MATLAB is presented. Finally, the implementation of the LabVIEW program is conducted to support the MATLAB simulation. It was found that experiments show good agreements with the simulation results.

Nonlinear control of a DC motor

This paper deals with a nonlinear system where an online nonlinear control is applied to a DC motor. First, nonlinear model of the motor is explained. Next, based on the model, the nonlinearity is simulated using MATLAB. The simulations were on two nonlinearities, ideal relay and relay with hysteresis. To further investigate the relay with hysteresis, the implementation of the LabVIEW program is presented to verify the results obtained from the MATLAB simulations. It was found that experiments show good agreements with the simulation results.