High Ash Non Coking Coal preparation by Tribo-Electrostatic Technique

Tribo-electrostatic method is applied to beneficiate non-coking Indian thermal coal from Ramagundam coal mines containing nearly 45% ash content. The microscopic studies revealed that quartz and kaolinite are the dominant mine-rals whereas illite, goethite, siderite and pyrite are the minor inclusions in the coal. Contact electrification of ash forming minerals and coal matter has been carried out using different tribo-charger materials of Al, Cu, brass, perspex and teflon. The Cu tribo-charger found to be opti-mum to acquire differential charge between ash-forming inorganics and coal matter. The temperature effect on the magnitude of contact charge acquisition found to be sign-ificant. Tests on a laboratory in-house built triboelectro-static free-fall separator with minus 300 microns size fraction of coal showed that the ash content can be reduc-ed from 45% to about 18% and it is feasible to obtain a clean coal as judged by the washability studies. The results illustrate that the non-coking coals can be bene-ficiated using the scientific knowledge on the response and behaviour of coal and noncoal matters to electric charges

Turn-turn short circuit fault management in permanent magnet machines

This paper presents a systematic study on turn-turn short circuit fault and ways to manage them to provide a basis for comparison of the various options available. The possible methods to reduce the likelihood of the winding SC fault and the fault mitigation techniques related to such faults are discussed. A Finite Element (FE) analysis of a surface-mount Permanent Magnet (PM) machine under application of different mitigation techniques during a turn-turn fault is presented. Both machine and drive structural adaptations for different fault mitigation techniques are addressed. Amongst the investigated fault mitigation techniques, the most promising solution is identified and validated experimentally. It is shown that the shorting terminal method adopting vertical winding arrangement is an effective method in terms of the implementation, reliability and weight

Integrated GSM-UWB Fibonacci-type antennas with single, dual, and triple notched bands

© The Institution of Engineering and Technology 2017. This study presents four integrated Fibonacci-type Global System for Mobile (GSM) ultra-wideband (UWB) antennas with single, dual, and triple band-notched characteristics. These antennas have been designed to control potential interference in Wi-Max and WLAN bands. The antenna operates in the 900 MHz GSM band and also in the 3.2-11.9 GHz extended UWB band. The 900 MHz operating band can be further tuned to get the antenna to operate in a specific GSM band. Triple notches have been created at frequencies within several bands, such as 3.4 GHz Wi-Max (3.06-3.54 GHz), 4.23 GHz WLAN (3.59-4.86 GHz), and 6.35 GHz (5.93-7.15 GHz) with voltage standing wave ratio (VSWR) levels of 7.9, 11.3, and 7, respectively. These notch bands are also tuneable to some extent. The measured gain varies from -1.92 to 10.2 dBi. Measured radiation patterns of the antenna are also presented to validate its performance. The integrated antenna has a radiation efficiency in the range of 78- 98% in the UWB and 98% in the GSM band. The fidelity factor in time domain varies between 0.76 and 0.84, depending on the orientation of the antenna. This research confirms that the Fibonacci monopole can be used as a multiband antenna in GSM and UWB bands

Wideband and high-gain circularly polarised microstrip antenna design using sandwiched metasurfaces and partially reflecting surface

© The Institution of Engineering and Technology 2018 In this study, the authors propose a new type of metasurface, namely a sandwiched anisotropic metasurface, for converting a linearly polarised elliptical patch antenna into a wideband circularly polarised antenna. A partially reflecting surface (PRS) as a superstrate is further used to enhance the gain of the antenna. The design rules of the antenna are also presented. The combined metasurface and the PRS-based patch antenna is designed on a low-cost substrate FR-4. The realised 3 dB axial ratio bandwidth (ARBW) of the antenna is 1.01 GHz (3.55-4.56 GHz), its impedance matching bandwidth is 1.33 GHz (3.08-4.41 GHz), and its peak gain varies from 7 to 7.84 dB within the band. By placing the PRS superstrate above the antenna, gain further improves to 9.32 dBi without degrading the performance of the antenna. Measured results are presented to validate the antenna performance and results are compared against a large number of similarly available antenna