Thomas Decomposition and Nonlinear Control Systems

This paper applies the Thomas decomposition technique to nonlinear control systems, in particular to the study of the dependence of the system behavior on parameters. Thomas' algorithm is a symbolic method which splits a given system of nonlinear partial differential equations into a finite family of so-called simple systems which are formally integrable and define a partition of the solution set of the original differential system. Different simple systems of a Thomas decomposition describe different structural behavior of the control system in general. The paper gives an introduction to the Thomas decomposition method and shows how notions such as invertibility, observability and flat outputs can be studied. A Maple implementation of Thomas' algorithm is used to illustrate the techniques on explicit examples

A sonographic spectrum of psoriatic arthritis: “the five targets”

Ultrasound is a rapidly evolving technique that is gaining an increasing success in the assessment of psoriatic arthritis. Most of the studies have been aimed at investigating its ability in the assessment of joints, tendons, and entheses in psoriatic arthritis patients. Less attention has been paid to demonstrate the potential of ultrasound in the evaluation of skin and nail. The aim of this pictorial essay was to show the main high-frequency grayscale and power Doppler ultrasound findings in patients with psoriatic arthritis at joint, tendon, enthesis, skin, and nail level

Formation mechanism of graphite hexagonal pyramids by argon plasma etching of graphite substrates

International audienceA new graphite crystal morphology has been recently reported, namely the graphite hexagonal pyramids (GHPs). They are hexagonally-shaped crystals with diameters ranging from 50 to 800 nm and a constant apex angle of 40 degrees. These nanostructures are formed from graphite substrates (flexible graphite and highly ordered pyrolytic graphite) in low pressure helicon coupling radiofrequency argon plasma at 25 eV ion energy and, purportedly, due to a physical etching process. In this paper, the occurrence of peculiar crystals is shown, presenting two hexagonal orientations obtained on both types of samples, which confirms such a formation mechanism. Moreover, by applying a pretreatment step with different time durations of inductive coupling radiofrequency argon plasma, for which the incident ion energy decreases at 12 eV, uniform coverage of the surface can be achieved with an influence on the density and size of the GHPs

Signature of polycyclic aromatic hydrocarbons in very low-pressure helium plasmas

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PAHs as dust formation precursors in really-low pressure plasmas

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PAHs as dust formation precursors in really-low pressure plasmas

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Analysis of the high-energy electron population in surface-wave plasma columns in presence of collisionless resonant absorption

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Charging and heating processes of dust particles in an electron cyclotron resonance plasma

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Transport of Dust Particles in Very Low-Pressure Magnetized Plasma Studied by Rapid Imaging

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