nonlinear resonators
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This work is focused on investigation of applicability of two widely used model equations for description of nonlinear standing waves in constant-cross-sectioned resonators. The investigation is based on the comparison of numerical solutions of these model equations with solutions of more accurate model equations whose validity has been verified experimentally in a number of published papers.
- MeSH
- akustika * MeSH
- časové faktory MeSH
- nelineární dynamika * MeSH
- numerická analýza pomocí počítače MeSH
- počítačová simulace MeSH
- pohyb těles MeSH
- reprodukovatelnost výsledků MeSH
- tlak MeSH
- vibrace MeSH
- zvuk * MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
Předmětem článkuje nelineární robustní 3D filtrace MR obrazu, která umožňuje realizaci vysokého prostorového rozlišení při zachování únosné míry šumu. Důraz je kladen na rozdílné vlastnosti 2D a 3D filtrů a na rozdíl mezi lineárními a nelineániími robustními technikami filtrace. Základní pojmy jsou vysvětleny v matematicky odlehčené podobě a postupy nelineární filtrace jsou dokumentovány na číselných příkladech. Rozdíly mezi jednotlivými metodami jsou zobrazeny v grafické formě. Software pro nelineární filtraci 3D MR obrazů je realizován v prostředí Matlab a zahrnuje čtení souborů podle normy Interfile, vlastní numerické výpočty, grafickou prezentaci a archivaci výsledků.
Nonlinear robust 3D filtering of MR image is a subject of the paper. It enables to realize high space resolution with guaranteed acceptable level of noise. Different properties of 2D and 3D filters plus the difference between linear and nonlinear robust techniques are pointed. Basic terms are explained in simple and „light" mathematical form and the procedures of nonlinear filtering are explained on numerical examples. The method differences are depicted using graphical form. The software for nonlinear filtering of 3D MR images is realized in Matlab environment including Interfile reading, numeric calculations, graphical presentation and result archivation.
In this paper, linearized approximations of both the forward and the inverse problems of resonant ultrasound spectroscopy for the determination of mechanical properties of thin surface layers are presented. The linear relations between the frequency shifts induced by the deposition of the layer and the in-plane elastic coefficients of the layer are derived and inverted, the applicability range of the obtained linear model is discussed by a comparison with nonlinear models and finite element method (FEM), and an algorithm for the estimation of experimental errors in the inversely determined elastic coefficients is described. In the final part of the paper, the linearized inverse procedure is applied to evaluate elastic coefficients of a 310 nm thick diamond-like carbon layer deposited on a silicon substrate.
- MeSH
- diagnostické techniky kardiovaskulární přístrojové vybavení využití MeSH
- fraktály MeSH
- lidé MeSH
- magnetismus MeSH
- počítačová simulace využití MeSH
- počítačové systémy využití MeSH
- rozhodovací podpůrné systémy pro řízení využití MeSH
- statistika jako téma MeSH
- teoretické modely MeSH
- umělá inteligence MeSH
- Check Tag
- lidé MeSH
During phonation, the respiratory, the phonatory, and the resonatory parts of the voice organ can interact, where physiological action in one subsystem elicits a direct effect in another. Here, three major subsystems of these synergies are reviewed, creating a model of voice subsystem interactions: (1) Vocal tract adjustments can influence the behavior of the voice source via nonlinear source-tract interactions; (2) The type and degree of vocal fold adduction controls the expiratory airflow rate; and (3) The tracheal pull caused by the respiratory system affects the vertical larynx position and thus the vocal tract resonances. The relevance of the presented model is discussed, suggesting, among others, that functional voice building work concerned with a particular voice subsystem may evoke side effects or benefits on other subsystems, even when having a clearly defined and isolated physiological target. Finally, four seemingly incongruous historic definitions of the concept of singing voice "support" are evaluated, showing how each of these pertain to different voice subsystems at various levels of detail. It is argued that presumed discrepancies between these definitions can be resolved by putting them into the wider context of the subsystem interaction model presented here, thus offering a framework for reviewing and potentially refining some current and historical pedagogical approaches.
- MeSH
- anatomické modely * MeSH
- biomechanika MeSH
- dýchání * MeSH
- fonace * MeSH
- hlasové řasy anatomie a histologie fyziologie MeSH
- kvalita hlasu * MeSH
- lidé MeSH
- nelineární dynamika * MeSH
- rezistence dýchacích cest MeSH
- systémová integrace * MeSH
- trachea anatomie a histologie fyziologie MeSH
- vibrace MeSH
- zpívání * MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
- MeSH
- algoritmy MeSH
- financování organizované MeSH
- lidé MeSH
- magnetická rezonanční tomografie metody využití MeSH
- mapování mozku metody přístrojové vybavení MeSH
- počítačové zpracování obrazu MeSH
- rozpoznávání automatizované metody MeSH
- schizofrenie diagnóza MeSH
- zobrazování trojrozměrné využití MeSH
- Check Tag
- lidé MeSH
The structured population LPA model is studied. The model describes flour beetle (Tribolium) population dynamics of four stage populations: eggs, larvae, pupae and adults with cannibalism between these stages. We concentrate on the case of non-zero cannibalistic rates of adults on eggs and adults on pupae and no cannibalism of larvae on eggs, but the results can be numerically continued to non-zero cannibalism of larvae on eggs. In this article two-parameter bifurcations in LPA model are analysed. Various stable and unstable invariant sets are found, different types of hysteresis are presented and abrupt changes in dynamics are simulated to explain the complicated way the system behaves near two-parameter bifurcation manifolds. The connections between strong 1:2 resonance and Chenciner bifurcations are presented as well as their very significant consequences to the dynamics of the Tribolium population. The hysteresis phenomena described is a generic phenomenon nearby the Chenciner bifurcation or the cusp bifurcation of the loop.
