Journal ArticleDOI
Modeling of the Lung Impedance Using a Fractional-Order Ladder Network With Constant Phase Elements
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TLDR
This study investigates the identification of a model for the respiratory tree by means of its electrical equivalent based on intrinsic morphology, and reveals that both models characterize the data well, whereas the averaged CPE values are supraunitary and subunitary for the ladder network and the lumped model, respectively.Abstract:
The self similar branching arrangement of the airways makes the respiratory system an ideal candidate for the application of fractional calculus theory. The fractal geometry is typically characterized by a recurrent structure. This study investigates the identification of a model for the respiratory tree by means of its electrical equivalent based on intrinsic morphology. Measurements were obtained from seven volunteers, in terms of their respiratory impedance by means of its complex representation for frequencies below 5 Hz. A parametric modeling is then applied to the complex valued data points. Since at low-frequency range the inertance is negligible, each airway branch is modeled by using gamma cell resistance and capacitance, the latter having a fractional-order constant phase element (CPE), which is identified from measurements. In addition, the complex impedance is also approximated by means of a model consisting of a lumped series resistance and a lumped fractional-order capacitance. The results reveal that both models characterize the data well, whereas the averaged CPE values are supraunitary and subunitary for the ladder network and the lumped model, respectively.read more
Citations
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What Is Systems Analysis
TL;DR: Laxenburg has a new director but an uncertain future and it also needs a policy.
Journal ArticleDOI
Fractional Order Modeling of Large Three-Dimensional RC Networks
Roberto Kawakami Harrop Galvão,Sillas Hadjiloucas,Karl Heinz Kienitz,Henrique Mohallem Paiva,Rubens Junqueira Magalhães Afonso +4 more
TL;DR: The proposed analysis can be used to model charge migration in amorphous materials, which may be associated to specific macroscopic or microscopic scale fractal geometrical structures in composites displaying a viscoelastic electromechanical response, as well as to model the collective responses of processes governed by random events described using statistical mechanics.
Journal ArticleDOI
And I say to myself: “What a fractional world!”
TL;DR: In this paper, several complex systems in the perspective of fractional dynamics are discussed, including deoxyribonucleic acid decoding, financial evolution, earthquakes events, global warming trend, and musical rhythms.
Journal ArticleDOI
Application of Fractional Calculus Theory to Robust Controller Design for Wind Turbine Generators
TL;DR: In this paper, a robust controller design method for wind turbine generators using the concepts of fractional calculus is presented, which uses isodamping feature, which desensitizes the phase-frequency variations about a gain crossover frequency.
Journal ArticleDOI
From Traditional to Fractional PI Control: A Key for Generalization
TL;DR: The fractional-order PI controller is a modified version of the PI controller that originated with fractional calculus, known as a generalization for classical calculus, and it is attracting increased interest in control system design uses.
References
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Book
The Fractal Geometry of Nature
TL;DR: This book is a blend of erudition, popularization, and exposition, and the illustrations include many superb examples of computer graphics that are works of art in their own right.
Journal ArticleDOI
The Fractal Geometry of Nature
TL;DR: A blend of erudition (fascinating and sometimes obscure historical minutiae abound), popularization (mathematical rigor is relegated to appendices) and exposition (the reader need have little knowledge of the fields involved) is presented in this article.
Journal ArticleDOI
An Interior Trust Region Approach for Nonlinear Minimization Subject to Bounds
Thomas F. Coleman,Yuying Li +1 more
TL;DR: In this paper, a trust region approach for minimizing nonlinear functions subject to simple bounds is proposed, where the trust region is defined by minimizing a quadratic function subject only to an ellipsoidal constraint and the iterates generated by these methods are always strictly feasible.
Journal ArticleDOI
The forced oscillation technique in clinical practice: methodology, recommendations and future developments
Ellie Oostveen,D. MacLeod,H. Lorino,Ramon Farré,Zoltán Hantos,Kristine Desager,François Marchal +6 more
TL;DR: The forced oscillation technique (FOT) is a non-invasive method with which to measure respiratory mechanics as mentioned in this paper, which employs small-amplitude pressure oscillations superimposed on the normal breathing and therefore has the advantage over conventional lung function techniques that does not require the performance of respiratory manoeuvres.