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Full-Text Articles in Physical Sciences and Mathematics

Lensed Cosmic Microwave Background Constraints On Post-General Relativity Parameters, P. Serra, A. Cooray, S. F. Daniel, R. R. Caldwell, A. Melchiorri Oct 2009

Lensed Cosmic Microwave Background Constraints On Post-General Relativity Parameters, P. Serra, A. Cooray, S. F. Daniel, R. R. Caldwell, A. Melchiorri

Dartmouth Scholarship

No abstract provided.


Flexoelectricity Of A Calamitic Liquid Crystal Elastomer Swollen With A Bent-Core Liquid Crystal, M. Chambers, R. Verduzco, J. T. Gleeson, S. Sprunt, Antal Jakli Sep 2009

Flexoelectricity Of A Calamitic Liquid Crystal Elastomer Swollen With A Bent-Core Liquid Crystal, M. Chambers, R. Verduzco, J. T. Gleeson, S. Sprunt, Antal Jakli

Antal Jakli

We have measured the electric current induced by mechanical distortion of a calamitic liquid crystal elastomer (LCE) swollen with a low molecular weight bent-core nematic (BCN) liquid crystal, and have determined, for the first time, the bend flexoelectric coefficient e(3) of such a BCN-LCE composite. In one method, we utilise air-pressure to induce a mechanical bend deformation and flexoelectric polarization in a BCN-LCE film, and then measure the polarization current as a function of time. An alternative technique uses a rotary-motor driven scotch yoke to periodically flex the BCN-LCE; in this case, the magnitude and phase of the induced current …


High Resolution Solar Observations From First Principles To Applications, Angelo P. Verdoni Aug 2009

High Resolution Solar Observations From First Principles To Applications, Angelo P. Verdoni

Dissertations

The expression "high-resolution observations" in Solar Physics refers to the spatial, temporal and spectral domains in their entirety. High-resolution observations of solar fine structure are a necessity to answer many of the intriguing questions related to solar activity. However, a researcher building instruments for high-resolution observations has to cope with the fact that these three domains often have diametrically opposed boundary conditions. Many factors have to be considered in the design of a successful instrument. Modern post-focus instruments are more closely linked with the solar telescopes that they serve than in past. In principle, the quest for high-resolution observations already …


Polarization Variability Arising From Clumps In The Winds Of Wolf-Rayet Stars., Qing-Kang Li, Joseph Cassinelli, John Brown, Richard Ignace May 2009

Polarization Variability Arising From Clumps In The Winds Of Wolf-Rayet Stars., Qing-Kang Li, Joseph Cassinelli, John Brown, Richard Ignace

ETSU Faculty Works

The polarimetric and photometric variability of Wolf-Rayet (WR) stars as caused by clumps in the winds, is revisited. In the model which is improved from Li et al. 2000, the radial expansion of the thickness is accounted for, but we retain the dependence on the beta velocity law, stellar occultation effects. We again search for parameters that can yield results consistent with observations in regards to the mean polarization, the ratio of polarimetric to photometric variability, and the volume filling factor. Clump generation and spatial distribution are randomized by the Monte Carlo method so as to produce clumps which are, …


Insulation Condition Assessment Of Power Transformers Using Accelerated Ageing Tests, Mohammad Mirzaie, Ahmad Gholami, Hamid Reza Tayebi Jan 2009

Insulation Condition Assessment Of Power Transformers Using Accelerated Ageing Tests, Mohammad Mirzaie, Ahmad Gholami, Hamid Reza Tayebi

Turkish Journal of Electrical Engineering and Computer Sciences

Thermal stress due to losses and environment temperature causes degradation to paper/oil insulation systems in transformers, even at operating temperature. Experience indicates that thermal ageing of oil and paper in power transformers leads to the change of some insulation characteristics. In this paper, insulating papers immersed in oil have been acceleratory aged at 140, 150, and 160 °C under laboratory conditions. Some of the oil properties, such as water content, breakdown voltage, acidity, together with the aged insulating paper properties such as electric strength, dielectric dissipation factor and tensile strength were measured and analyzed. Also, insulation system conditions under thermal …