Two robust nonlinear controllers along with a nonlinear observer have been developed in this study to control a 1D nonlinear flexible spacecraft. The first controller is based on dynamic inversion, while the second one is composed of dynamic inversion and µ-synthesis controllers. The extension of dynamic inversion approach to flexible spacecraft is impeded by the non-minimum phase characteristi...

In this paper, a method is proposed to invert permeability from seismoelectric logs in fluid-saturated porous formations. From the analysis of both the amplitude and the phase of simulated seismoelectric logs, we find that the Stoneley wave amplitude of the ratio of the converted electric field to the pressure (REP) is sensitive to porosity rather than permeability while the tangent of the REP’...

[1] A three-stage inversion technique for surface wave tomography is applied to the Australian region. The inversion procedure consists of three independent processes. In the first stage, path-specific one-dimensional (1-D) shear velocity profiles are derived from multimode waveform inversion to provide dispersion information. The information from all paths is then combined to produce multimode...

Membranes were prepared from a castmg solution of a water-soluble polymer, poly (vmyl pyrrohdone) (PVP), and a membrane forming polymer, poly (ether sulfone), m l-methyl-2-pyrrohdone (NMP) as solvent by immersing them m mixtures of water and NMP It was found that the addltlon of PVP to the ternary system suppresses the formatlon of macrovolds m the sub-layer, while the ultraflltratlon-type top-...

We describe a class of continuously phase-modulated radiation pulses that result in coherent population inversion on resonance as well as over a large range of transition frequencies and radiation field strengths. This is a population-inversion analogy to self-induced transparency. Simulations of the inversion properties of' the modulated inversion pulse (MIP) are presented. It is shown that th...

Stable inversion is a completely new approach to the output tracking control of nonminimum phase nonlinear systems. It not only offers exact reproduction of a given reference output trajectory but also guarantees stability of all external and internal signals. After a brief review of the stable inversion problem, the paper establishes a finite energy property of stable inverses. That is, out of...

A novel technique to achieve output tracking via stable inversion of non-minimum phase linear systems is presented wherein the desired signal is obtained from field measurements, and hence corrupted by noise. The earlier approach to stable inversion does not take into account the noise in the system. The unknown input decoupled observer approach is applicable only to minimum phase systems. More...

A novel technique to achieve output tracking via stable inversion of non-minimum phase linear systems is presented wherein the desired signal is obtained from field measurements, and hence corrupted by noise. The earlier approach to stable inversion does not take into account the noise in the system. The unknown input decoupled observer approach is applicable only to minimum phase systems. More...

[1] Abstract: We predict plate motions from a comprehensive inversion of theoretical estimates of tectonic forces in order to evaluate the relative importance of these and the uncertainties of such models. Plate-driving forces from the mantle are calculated using global flow models that are driven by tomography and subduction-derived density fields. Observed and predicted plate velocities agree...