The spectra of several X–ray binary pulsars display a clear soft excess, which in most cases can be described with a blackbody model, above the main power–law component. While in the high–luminosity sources it is usually characterized by low temperature (kT < 0.5 keV) and large emission radius (R > 100 km), in the two persistent and low–luminosity pulsars 4U 0352+309 and RX J0146.9+6121 this co...

We analyze the XMM-Newton dataset of the interacting cluster of galaxies Abell 3528 located westward in the core of the Shapley Supercluster, the largest concentration of mass in the nearby Universe. A3528 is formed by two interacting clumps (A3528-N at North and A3528-S at South) separated by 0.9 h −1 70 Mpc at redshift 0.053. XMM-Newton data describe these clumps as relaxed structure with an ...

In this paper, we investigate the convergence behaviour of a class of regularized Newton methods for the solution of nonlinear inverse problems. In order to keep the overall numerical effort as small as possible, we propose to solve the linearized equations by certain semiiterative regularization methods, in particular, iterations with optimal speed of convergence. Our convergence rate analysis...

The aim of this work, is to evaluate the value of a fuzzy integral by applying the Newton-Cotes integration rules via a reliable scheme. In order to perform the numerical examples, the CADNA (Control of Accuracy and Debugging for Numerical Applications) library and the CESTAC (Controle et Estimation Stochastique des Arrondis de Calculs) method are applied based on the stochastic arithmetic. By ...

Newton-Cotes quadrature rules are based on polynomial interpolation in a set of equidistant points. They are very useful in applications where sampled function values are only available on a regular grid. Yet, these rules rapidly become unstable for high orders. In this paper we review two techniques to construct stable high-order quadrature rules using equidistant quadrature points. The stabil...

The purpose of this paper is to reduce the complexity computing components integral Fm-transform, m≥0, whose analytic expressions include definite integrals. We propose use nontrivial quadrature rules with nonuniformly distributed integration points instead widely used Newton–Cotes formulas. As weight function that determines orthogonality, we choose generating fuzzy partition associated Fm-tra...

In many applications of ageand size-structured population models, there is an interest in obtaining good approximations of total population numbers rather than of their densities. Therefore, it is reasonable in such cases to solve numerically not the PDE model equations themselves, but rather their integral equivalents. For this purpose quadrature formulae are used in place of the integrals. Si...

Fractional directional integrals are the extensions of the Riemann-Liouville fractional integrals from oneto multi-dimensional spaces and play an important role in extending the fractional differentiation to diverse applications. In numerical evaluation of these integrals, the weakly singular kernels often fail the conventional quadrature rules such as Newton-Cotes and Gauss-Legendre rules. It ...

Pricing Asian options is a long standing hard problem since there is no analytical formula for the probability density of its payoff even when the process of the underlying asset follows the simple lognormal diffusion process. It is known that the option payoff can be expressed as a recursive function of sums of independent random variables. As a result, the density function of the option payof...