In the paper, “Partial Face Recognition”, K Rama Linga Reddy, G R Babu and Lal Kishore conduct a systemic study to assess the performance of face recognition techniques when partial faces are used for identification. In this study, two partial face recognition approaches have been proposed. In the first, artificial neural network is used as the classifier for multi-scaled face components, such as eyes, nose and mouth. The second method is based on linear discrimination features of face components. It is found that with partial face (face components), the percentage of recognition drops only slightly, compared to the full face recognition, and that eyes play a significant role in recognition.

The paper, “An NN-Based Three-Phase Three-Wired Hybrid Active Power Filter Under Non-Ideal Mains Voltages”, by Satya Prakash Dubey and Anurag Singh Tomer deals with the network-based control scheme for DC link voltage regulation and harmonic filtering using parallel hybrid active power filter. The neural network extracts fundamental frequency component from non-sinusoidal and unbalanced currents and then generates the required reference signals. Simulation results obtained under unbalanced and non-sinusoidal source and load have been presented to demonstrate the effectiveness of the proposed controller.

The transmission of Voice over Internet Protocol (VoIP) requires signal processing for reliable and efficient performance over the computer and the communication platform. Hardeep Singh Dalhio, M Mian and Jasvir Singh, in their paper, “VoIP Signal Processing in Digital Domain”, present a simulation model for voice processing over Internet protocol. The digital filtering algorithm is implemented on a degraded VoIP speech signal.

In any wireless communication channel, the signal can travel from the transmitter to the receiver in several paths due to the reflections of the propagating waves from a large, smooth surface and due to the diffractions that take place when there are obstructions in the radio path. The paper, “A Comparison of Rayleigh and Rician Fading Channels Under Frequency-Selective Fading”, by P Narasimha Murthy and R V S Satyanarayana, deals with the multi-path fading and motion-induced fading, which are the two most severe performance limiting phenomena in wireless environments. They analyze the Rayleigh and Rician fading channels under frequency-selective fading in terms of error probability and show that due to the presence of an LOS component, the Rician fading exhibits less error probability than the Rayleigh fading.

In the paper, “Grid-Connected PV System for PID Controller Using MATLAB”, by R Sivakumar and N Suthanthiravanitha, a single-phase five-level photovoltaic (PV) inverter topology for grid-connected system is designed. The PV arrays are connected to five-level inverter. The DC power from the PV array is applied to PWM inverter, which is controlled by Proportional-Integral-Derivative (PID) controller. The authors propose a digital PID current control algorithm for implementation in the grid-connected PV system.

The paper, “Design of a Wireless Audio Link for a Farm Settlement in the North Central Area of Nigeria”, by Paul Abraham-Attah, John Jiya Musa and Yahaya Dantani Daudu, describes the design of an audio link which is aimed at transmitting audio wirelessly using high power infrared beam frequency modulation within a localized farm settlement. The modulation is designed with a linear audio amplifier that drives two infrared diodes connected in series across a distance, which is a function of power delivered to the diodes. The wireless audio linking system is a frequency modulated scheme, in which the received signal strength at the receiver is an inverse of the distance separating the receiver and the transmitter. To cover a large distance, a number of photodiodes are used.

The optimum performance of electrical machines can be obtained by following proper maintenance strategies. The paper, “Condition-Based Predictive Maintenance Strategy for Electrical Machines: A User’s Perspective”, gives some insights into different maintenance techniques, and the authors Jaideep Gupta, A K Wadhwani and S Wadhwani stress the importance of safety and integrity.

-- MSR Murty
Consulting Editor