We present an analysis of early BAT and XRT data for 107 gamma–ray bursts (GRBs) observed by the Swift satellite. We use these data to examine the behaviour of the X-ray light curve and propose a classification scheme for GRBs based on this behaviour. As found for previous smaller samples, the earliest X-ray light curve can be well described by an exponential which relaxes into a power law, oft...

The spatially resolved diffusive dynamic cross correlations of a pair of colloids in dense quasi-two-dimensional monolayers of identical particles are studied experimentally and theoretically at early times where motion is Fickian. In very dense systems where strong oscillatory equilibrium packing correlations are present, we find an exponential decay of the dynamic cross correlations on small ...

In the present work, FGM shells integrated with magnetostrictive layers acting as distributed sensors and actuators are modeled to control vibration attenuation of FGM shells with simply supported boundaryconditions. To achieve a mechanism for actively control of the oscillation amplitude of the integrated structure, a negative velocity proportional feedback control law is implemented in the st...

In this study, free vibration of functionally graded rectangular plates for various types of boundary conditions has been presented . The properties of the plate are assumed as power- law form along the thickness direction , while poisson's ratio is kept constant. the linear vibration equations of functionally graded rectangular plates are derived based on first order shear deformation theory b...

The thermomechanical buckling of simply supported thin shallow spherical shells made of functionally graded material is presented in this paper. A metal-ceramic functionally graded shell with a power law distribution for volume fraction is considered, where its properties vary gradually through the shell thickness direction from pure metal on the inner surface to pure ceramic on the outer surfa...

In correcting a small mistake in [10], we can prove a new result on non-exponential stability for a coupled system arising in resonators. This also gives another (surprising and) simple example for a thermoelastic system changing from exponential stability to non-exponential stability when changing from Fourier’s law to Cattaneo’s law in the modeling of heat conduction.

Gas holdup and bubble size are important parameters for simulation and designing in bubble column reactors. Because based on these parameters, the available gas-liquid interfacial area is defined for mass transfer. In this paper, the results of applying magnetic fields on the velocity field and volume fraction of gas holdup are reported. Hydrodynamics of the bubble column in the reactors is inv...

In this paper a study on the vibration of thin cylindrical shells with ring supports and made of functionally graded materials (FGMs) composed of stainless steel and nickel is presented. The properties are graded in the thickness direction according to a volume fraction power-law distribution.The cylindrical shells with ring supports which are arbitrarily placed along the shell and impose zero ...

A mesh-free method based on moving least squares approximation (MLS)  and weak form of governing equations including two dimensional equations of motion and Maxwell’s equation is used to analyze the free vibration of functionally graded piezoelectric material (FGPM) beams. Material properties in beam are determined using a power law distribution. Essential boundary conditions are imposed by the...

One challenge associated with the simulation of buried detonations involves the treatment of the multiphase flow phenomena related to the soil. At the moment when the soil “shatters” into a dense particulate cloud with detonation products escaping through the soil particles, the continuum model that assumes a single velocity shared by the blast gas and the soil at any given point no longer hold...