Distributed Observer‐based Stabilization of Nonlinear Multi‐agent Systems with Sampled‐data Control

In this paper, the distributed observer‐based stabilization problem of multi‐agent systems under a directed graph is investigated. Distributed observer‐based control protocol with sampled‐data information is proposed. The dynamics of each agent contain a nonlinear part, which is supposed to be general Lipschitz. In order to stabilize the states of the whole network, all the nodes utilize the relative output estimation error at sampling instants and only a small fraction of nodes use the absolute output estimation error additionally. By virtue of the input‐to‐state stability (ISS) property and the Lyapunov stability theory, an algorithm to design the control gain matrix, observer gain matrix, coupling strength as well as the allowable sampling period are derived. The conditions are in the form of LMIs and algebraic inequality, which are simple in form and easy to verify. Some further discussions about the solvability of obtained linear matrix inequalities (LMIs) are also given. Lastly, an example is simulated to further validate the obtained results.     

Coupled stochastic gradient identification algorithms for multivariate output-error systems using the auxiliary model

This paper considers the gradient based identification problem of a multivariate output-error system. By using the auxiliary model identification idea and the coupling identification concept, an auxiliary model based stochastic gradient (AM-SG) algorithm and a coupled AM-SG algorithm are presented. The results indicate that the parameter estimation errors converge to zero under the persistent excitation conditions. The simulation examples confirm the theoretical results.     

Heat and mass transfer effects on peristaltic flow of an Oldroyd‐B fluid in a channel with compliant walls

This investigation describes the peristaltic motion of a magnetohydrodynamic (MHD) Oldroyd‐B fluid with heat and mass transfer. An incompressible Oldroyd‐B fluid is considered in a channel with flexible walls. The relevant equations are developed by employing equations of continuity, momentum, energy, and concentration. Expressions of stream function, temperature, concentration field, and heat transfer coefficient are presented when the wave number is small. The obtained solutions are graphically discussed for the several interesting parameters entering into the problem. It is found that relaxation and retardation times have opposite effects on the size of the trapped bolus. © 2011 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.20380     

Radiation effects on MHD flow in a porous space

This paper deals with the study of the radiation effects on the magnetohydrodynamic (MHD) flow of an incompressible viscous fluid in a porous space. The flow is induced due to a non-linear stretching sheet. Two cases of heat transfer analysis are discussed. These are: (i) the sheet with constant surface temperature (CST case) and (ii) the sheet with prescribed surface temperature (PST case). By means of similarity transformation, the governing partial differential equations are reduced into highly non-linear ordinary differential equations. The resulting non-linear system has been solved analytically using a very efficient technique namely homotopy analysis method (HAM). Expressions for velocity and temperature fields are developed in series form. Convergence of the series solution is shown explicitly. The influence of various pertinent parameters is also seen on the velocity and temperature fields. The tabulated values of the wall shear stress and the Nusselt number show good agreement with the existing results.     

Spherical Wave Diffraction by a Slit in an Impedance Screen

An exact solution is developed for the problem of diffraction of an E-polarized and an H-polarized spherical waves by a slit in an impedance screen. This consideration is important in the sense that point sources are regarded as better substitutes for real sources than line sources/plane waves. The two independent problems are solved using the Fourier transform, the Wiener-Hopf technique and asymptotic approximations.     

On the influence of heat transfer in peristalsis with variable viscosity

This study concentrates on the heat transfer characteristics and endoscope effects for peristaltic flow of a third order fluid. Two models of variable viscosity are chosen. Both perturbation and numerical solutions are obtained in each case. A comparative study is also made between the two solutions. The importance of pertinent flow parameters entering into the flow modeling is discussed.     

Analysis of magnetic properties of nanoparticles due to applied magnetic dipole in aqueous medium with momentum slip condition

Neural Computing and Applications - This article examines the boundary layer flow of magnetic nanofluid over a stretching surface with velocity slip condition. Water is selected as a base liquid...     

Thin‐Film‐Based Integrated High‐Transition‐Temperature Superconductor Devices

Since the discovery of superconductivity at temperatures above the technologically promising liquid nitrogen temperatures, applications based on superconductors have expanded and are being put to commercial use. However, superconductivity at higher temperatures typically occurs in complex materials requiring stringent material and environmental constraints. Such restraints make the realization and integration of these materials with normal materials a nontrivial aspect. In this progress report, unique features of these superconductors in terms of their synthesis, physical properties determining interface electrical transport, and their applications are discussed. A detailed progress report on these applications with remarks on efforts taken to integrate these devices with traditional platforms and semiconducting materials is provided.