7,472 research outputs found
Palaeoecological evaluation of the recent acidification of Welsh lakes: 3. Llyns Conwy and Gamalt, Gwynedd
No full textPalaeoecological evaluation of the recent acidification of susceptible lakes. Methods utilised under DoE contract PECD 7/7/139 and the Royal Society SWAP Project
No full textStevenson Barrett, Music Faculty
No full textStevenson Barrett was a member of the Music faculty at Jacksonville State College (now Jacksonville State University) in Summer 1953-1954.https://digitalcommons.jsu.edu/lib-ac-histimg/6516/thumbnail.jp
Influence of ac ageing on space charge dynamics in LDPE
No full textPolymeric materials have been widely used as insulation in power industry due to their excellent electrical properties. However, these properties deteriorate in time irreversibly when the material is subjected to electric stress. Although space charge is believed to play an important role in ac ageing, exact mechanisms are poorly understood due to very limited experimental data. In the present work efforts have been made to investigate the influence of ac ageing on space charge dynamics in low-density polyethylene (LDPE). LDPE films with 200mm were aged at 50 kV/mm at 50 Hz for various times at ambient temperature. Space charge dynamics in the samples prior to and after ageing were monitored using the pulsed electroacoustic (PEA) technique under dc electric stress. The results indicate that there is a significant amount of homocharge accumulation in the unaged sample due to charge injection. These injected charges are the captured by the deep traps originated from the interface between crystalline and amorphous regions in LDPE. Ageing under ac condition does not necessarily lead to an increase in amount of charge in the bulk but leads to an increase in mobility of charge carriers. Chemical analysis by infrared spectroscope (FTIR) reveals there are chemical changes taken place in the bulk of the material after ac ageing. It is believed that the chemical changes introduce shallow traps which promote the movement of charge carriers in the bulk. Consequently, the injected charges spread across the sample
Palaeoecological evaluation of the recent acidification of Welsh lakes: 2. Llyn Berwyn, Dyfed
No full text
A power sharing series power BJT array with isolated low voltage control for AC power control applications
No full textA technique for a continuously variable AC resistance using a series BJT array is presented. This array provides high power dissipation capability and uniform voltage and power distribution across the individual transistors. The array, controlled using a set of optoisolators to maintain the electrical isolation between the control circuits and the power stage, could be used as the basis to develop several useful techniques including a solid state AC regulator with comparable performance to the commonly used ferro-resonant systems; a linear AC electronic load suitable for testing UPS and other power conditioners; and, in other AC power control applications such as switching capacitors in AC resonant circuits
Horace Lee Stevenson, Associate Professor
No full textHorace Lee Stevenson was an Associate Professor of History at Jacksonville State College (now Jacksonville State University) in 1963-1964.https://digitalcommons.jsu.edu/lib-ac-histimg/29397/thumbnail.jp
Palaeoecological evaluation of there recent acidification of Welsh lakes: 7. Llyn y Bi, Gwynedd
No full textAllen Stevenson, 1975-1976 Football Player
No full textAllen Stevenson was a member of the football team at Jacksonville State University in 1975-1976.https://digitalcommons.jsu.edu/lib-ac-histimg/47828/thumbnail.jp
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