The dynamics of an experimental electrodynamic loudspeaker is studied by using the tools of chaos theory and time series analysis. Delay time, embedding dimension, fractal dimension, and other empirical quantities are determined from experimental data. Particular attention is paid to issues of stationarity in a system in order to identify sources of uncertainty. Lyapunov exponents and fractal dimension are measured using several independent techniques. Results are compared in order to establish independent confirmation of low dimensional dynamics and a positive dominant Lyapunov exponent. We thus show that the loudspeaker may function as a chaotic system suitable for low dimensional modeling and the application of chaos control techniques.
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http://dx.doi.org/10.1121/1.2967843 | DOI Listing |
Sci Rep
January 2025
School of Mechanical and Engineering, Liaoning Technical University, Fuxin, 123000, China.
As the depth of coal mining in China continues to increase, the fracturing of coal rock masses has an increasingly complex impact on the surrounding rock roadways. The majority of the mine's roadways run through coal rock masses with hard roofs and soft bottoms, which typically exhibit complex dynamic behaviour. To further research the mechanical behaviour and fracture evolution of coal rock masses under hard-roof and soft-floor conditions, the study is based on the majority of working faces in a mine, which have hard roofs and soft floors.
View Article and Find Full Text PDFActa Bioeng Biomech
June 2024
1Faculty of Rehabilitation, Józef Piłsudski University of Physical Education in Warsaw, Warsaw, Poland.
: External factors can disrupt postural control, but the intricate workings of the postural control system enable an appropriate response. This study seeks to assess how external perturbations affect postural control. : Twenty women participated in study, which consisted four trials involved quiet standing and experiencing induced perturbations by being struck with a boxing bag from the back, right, and left sides, respectively.
View Article and Find Full Text PDFJ Vis Exp
January 2025
Fever Outpatient Clinic, Dongzhimen Hospital, Affiliated to Beijing University of Chinese Medicine;
Non-invasive assessment of pulmonary nodule malignancy remains a critical challenge in lung cancer diagnosis. Traditional methods often lack precision in differentiating benign from malignant nodules, particularly in the early stages. This study introduces an approach using multifractal spectrum analysis to quantitatively evaluate pulmonary nodule characteristics.
View Article and Find Full Text PDFOphthalmic Physiol Opt
January 2025
Robert O Curle Ophthalmology Suite, Institute for Regeneration and Repair, The University of Edinburgh, Edinburgh, UK.
Purpose: To determine whether imaging features derived from fundus photographs contain 3D eye shape information beyond that available from spherical equivalent refraction (SER).
Methods: We analysed 99 eyes of 68 normal adults in the UK Biobank. An ellipsoid was fitted to the entire volume of each posterior eye (vitreous chamber without the lens)-segmented from magnetic resonance imaging of the brain.
Polymers (Basel)
January 2025
School of Civil Engineering and Transportation, Northeast Forestry University, Harbin 150040, China.
This article systematically investigated the improvement effect of polypropylene fiber (PPF) on the mechanical and freeze-thaw properties of alkali-activated fly ash slag concrete (AAFSC) with high fly ash content and cured at room temperature. Fly ash and slag were used as precursors, with fly ash accounting for 80% of the total mass. A mixed solution of sodium hydroxide and sodium silicate was used as alkali activator, and short-cut PPF was added to improve the performance of AAFSC.
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