Air University (Islamabad)

About: Air University (Islamabad) is a education organization based out in Islamabad, Pakistan. It is known for research contribution in the topics: Heat transfer & Nanofluid. The organization has 923 authors who have published 1488 publications receiving 11164 citations.

Frequency Diverse Array Radar With Logarithmically Increasing Frequency Offset

Abstract: In recent years, frequency diverse array (FDA) radar with uniform interelement frequency offset has been proposed and investigated. It has been shown that the beampattern of this form of radar is range-angle-dependent, and it exhibits maxima at multiple range values. Due to the multiple maxima, a number of reflectors located at any of the maxima can interfere the target-return, thus deteriorating signal-to-interference-plus-noise ratio (SINR). In this letter, we have proposed FDA with logarithmically increasing frequency offset to achieve a beampattern with a single maximum at the target location. A transmitter for the proposed radar system has been described and analyzed mathematically. Furthermore, the transmit beampattern has been derived and plotted and compared to that of phased-array radar (PAR) and the existing forms of FDA employing uniform frequency offset.

Factors affecting Halal purchase intention – evidence from Pakistan’s Halal food sector

Abstract: Purpose – The purpose of this paper is to identify and determine the connection of various antecedents from educational literary works with Halal purchase intention. It also aims to investigate which antecedents, among all antecedents, have the highest possible participation toward the development of Halal food purchase intention. Consumers across the globe have an ever increasing demand for Halal items nowadays. Similarly, food stuff in Halal category has an increased acceptance across the globe. Numerous researches have therefore focused on Halal food perception, Halal understanding and its approval in various areas of the world. Design/methodology/approach – A total of 300 respondents were taken from four major cities of Pakistan to examine the relationship of factors that influence customer’s Halal purchase intention. Data were collected through structured questionnaire having seven-point Likert scale. It was divided into eight sections with statements measuring Halal Awareness, Halal Marketing, Subje...

Review of harmonic analysis, modeling and mitigation techniques

Abstract: Power quality problems are manifested in voltage, current or frequency deviations causing malfunction of sensitive equipment. Integration of inverter connected PV and wind power plants, and rampant rise in nonlinear loads have led to harmonic problem in power system. Nonlinear loads and switched devices energized by sinusoidal sources or linear loads and switched devices with non-sinusoidal sources, produce harmonics in distribution system. Academic harmonic analysis study consists of modeling nonlinear loads to develop Norton and Thevenin equivalent circuits of devices for integration into harmonic analysis software. Experimental researchers often use harmonic analyzers to measure the harmonics in real systems to evaluate suitable mitigation alternatives. The distortive power losses force utilities to increase apparent power to maintain reliable and uniform power supply. Harmonic analyzers use data acquisition hardware and inbuilt software algorithms to perform onsite measurements. Harmonic analyzers help find true power factor, total harmonic distortions, reactive and distortive power losses. Use of shunt capacitance at unity power factor worsens the situation instead of supplying distortive power compensation. Active power factor correction techniques, using smart algorithm to cancel the distortive power, have been reviewed for further research. Nonlinear physics of harmonic phenomenon is described to explore its applications. Harmonic mitigation technologies have been compared, current state of the art technology reviewed and demonstrated by designing a harmonic filter. Measurement of harmonics, waveform distortions, and true power factor (TPF) of single and three phase electronic loads is carried out to test their compliance to harmonic standard limits. Energy conservation concept requires reduction of harmonics in distribution networks. This study found 60±10% reduction in power factor and more than 2% increase in line losses due to widespread use of nonlinear loads. Utility apparent power demand increases due to consumers’ inadvertent violation of IEC Standard 61000-3-2 and IEEE Standard 519–1992.