Abstract A poled piezoelectric ceramic such as Lead Zirconate Titanate (PZT) belongs to a C∞ crystal class, with ten independent material constants. If we consider losses, all the parameters can be represented in complex form 10 also have loss components associated them. Therefore, total of 20 constants are required obtain entire model. In this work, present procedure for determining complete r...

The Black Hole Binary source Swift J175.5-0127 remained in outburst for $\sim$ 12 years from May 2005 to April 2017. For most part of the outburst, Low Hard State (LHS) displaying transitions softer states only towards end short periods time. Quasi periodic Oscillations (QPOs) were observed Power Density Spectrum (PDS) during decay. A soft thermal component was required model spectrum LHS, whic...

We have undertaken an extensive study of X-ray data from the accreting millisecond pulsar XTE J1751–305 observed by RXTE and XMM-Newton during its 2002 outburst. In all aspects this source is similar to a prototypical millisecond pulsar SAX J1808.4–3658, except for the higher peak luminosity of 13 per cent of Eddington, and the optical depth of the hard X-ray source larger by factor ∼2. Its bro...

We study the vertical structure of the transition layer between an accretion disc and corona in the context of the existence of two-phase medium in thermally unstable regions. The disc is illuminated by hard X-ray radiation and satisfies the condition of hydrostatic equilibrium. We take into account the energy exchange between hot corona (∼ 10 K) and cool disc (∼ 10 K) through the radiative pro...

Accreting black holes radiate in one of several spectral states, switching from one to another for reasons that are as yet not understood. Using the best studied example, Cyg X-1, we identify the geometry and physical conditions characterizing these states. In particular, we show that in the hard state most of the accretion energy is dissipated in a corona-like structure which fills the inner f...

The X-ray spectra of Galactic binary systems dominated by a quasi-thermal component (disc dominated or high/soft state) are well described by a standard ShakuraSunyaev disc structure down to the last stable orbit around the black hole. This is not the case in the very high (or steep power law) state, where the X-ray spectra show both a strong disc component and strong, steep tail to higher ener...