AB Dor: A Single Star with RSCVn Like Activity in X-ray Band

Using the archival ROSAT PSPC observations, AB Dor is found to be variable in X-rays. The periodic variations are consistent with previously reported rotational period of 0.514 days. The average spectrum of AB Dor is best represented with two-temperature Raymond-Smith model with kT values of 0.19+/-0.07 and 1.17+/-0.02 keV. The quiescent luminosity of the system is found to be 4.36+/-0.6 10^30 ergs/s. A flare with a rise time of about 350 seconds is detected during which X-ray luminosity rises from 5.8+/-1.6 10^30 to 15.8+/-4.9 10^30 ergs/s. We conclude that AB Dor is very similar to the active components of RS CVn binaries and other active classes. In view of the wide separation from the binary companion Rst 137B, this activity must be intrinsic to the active star.Comment: 11 pages in PostScript including figures, accepted for publication in Astrophysics and Space Science, available at http://astroa.physics.metu.edu.tr/preprints.htm

An elastic-plastic stress analysis on a thermoplastic composite beam of arbitrary orientation supported from two ends acted upon with a force at the midpoint

An analytical elastic-plastic stress analysis is presented for a low density polyethylene thermoplastic composite reinforced by woven steel fibers supported at the ends acted upon with a force at the midpoint. The expansion of the plastic region and the residual stress component of sigma(x) are determined for theta = 0degrees, 15degrees, 30degrees and 45degrees orientation angles. Plastic yielding occurs for 0degrees and 45degrees orientation angles on the lower and upper surfaces of the beam at the same distances from the midpoint. But, it starts first at the lower surface for 15degrees and 30degrees orientation angles. The residual stress components are obtained after releasing the external force. The residual stress component of q, is maximum at the lower and upper surfaces. However, the intensity of the residual stress component tau(xy) is maxiumu on or around the x axis of the beam. The beam can be strengthened by using the residual stresses

An elastic-plastic stress analysis of simply supported metal-matrix composite beams under a transverse uniformly distributed load

An analytical elastic-plastic stress analysis is carried out on metal-matrix composite beams of arbitrary orientation, supported from two ends under a transverse uniformly distributed load. The composite layer consists of stainless steel fiber and aluminum matrix. The material is assumed to be perfectly plastic during the elastic-plastic solution. The intensity of the uniform force is chosen at a small value; therefore, the normal stress component sigma(y) is neglected in the elastic-plastic solution. The expansion of the plastic region and the residual stress component of sigma(x) are determined for orientation angles of 0, 30, 45, 60 and 90degrees. Plastic yielding occurs for 0degrees and 90degrees orientation angles on the lower and upper surfaces of the beam at the same distances from the mid-point. However, it starts first at the lower surface for 30, 45 and 60degrees orientation angles. The intensity of the residual stress component of a, is found to be maximum at the lower and upper surfaces; however, the intensity of the residual stress component of tau(xy) is a maximum on or around the x axis of the beam. (C) 2002 Elsevier Science Ltd. All rights reserved

An elastic-plastic stress analysis of simply supported thermoplastic composite beams under a transverse uniformly distributed load

WOS: 000177623300003An analytical elastic-plastic stress analysis is carried out on thermoplastic composite beams supported from two ends under transverse uniformly distributed load. The composite beams consist of woven steel fiber and thermoplastic matrix. The material is assumed to be perfectly plastic for the elastic-plastic solution. The intensity of the uniform force is chosen at a small value; therefore the normal stress components of sigma(y), is neglected during the elastic-plastic solution. The expansion of the plastic region and the residual stress component of sigma(x) are determined for 0degrees, 15degrees, 30 and 45degrees orientation angles. Plastic yielding occurs first 0degrees and 45degrees orientation angles on the lower and upper surfaces of the beam at the same distances from the ends. However; it starts first at the lower surface for 15degrees, 3degrees orientation angles. The intensity of the residual stress component of sigma(x) is found to be maximum at the lower and upper surfaces; whereas the intensity of residual stress component tau(xy) is maximum on or around the x axis of the beam

An elastic-plastic stress analysis of simply supported thermoplastic composite beams under a transverse uniformly distributed load

WOS: 000177623300003An analytical elastic-plastic stress analysis is carried out on thermoplastic composite beams supported from two ends under transverse uniformly distributed load. The composite beams consist of woven steel fiber and thermoplastic matrix. The material is assumed to be perfectly plastic for the elastic-plastic solution. The intensity of the uniform force is chosen at a small value; therefore the normal stress components of sigma(y), is neglected during the elastic-plastic solution. The expansion of the plastic region and the residual stress component of sigma(x) are determined for 0degrees, 15degrees, 30 and 45degrees orientation angles. Plastic yielding occurs first 0degrees and 45degrees orientation angles on the lower and upper surfaces of the beam at the same distances from the ends. However; it starts first at the lower surface for 15degrees, 3degrees orientation angles. The intensity of the residual stress component of sigma(x) is found to be maximum at the lower and upper surfaces; whereas the intensity of residual stress component tau(xy) is maximum on or around the x axis of the beam