The work presented here provides the guidelines and results for designing and implementing a highly sensitive modified Van der Pol - Duffing oscillator with a trigonometric damping function (VTD). This VTD can exhibit periodic and quasi-chaotic behavior necessary for application in weak signal detection. Here, we present two proposals: (1) A method based on a quasi-chaotic intermittent array (ANLIOA), whose all VTD parameters are calculated and fine-tuned toward a critical state between chaotic and periodic state through a Lyapunov exponent procedure, and (2) A method based on a single oscillator in an adaptive stopping oscillation system (ANLSOS), where VTD is established within an oscillatory regime. Both systems can detect non-stationary signals while reconstructing the time-frequency spectrogram in high resolution within severe noise conditions. The systems were adapted for the detection of a synthesized Doppler signal corresponding to the blood flow velocity profile from an artery. Comparative results using typical oscillators such as Duffing or Van der Pol demonstrate the superiority of the VTD oscillator in detection when used for both methods, whose mean absolute percentage error reached around 6% for a signal-to-noise ratio (SNR) of -10 dB. Furthermore, compared to other time-frequency methods, ANLIOA and ANLSOS promise high precision in detecting Doppler signals with low rates of frequency changes while minimizing energy emission and avoiding possible bio-thermal effects.
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http://dx.doi.org/10.1002/cnm.3794 | DOI Listing |
Catheter Cardiovasc Interv
October 2024
Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands.
Magn Reson Med
July 2023
Department of Radiology and Nuclear Medicine, Maastricht University Medical Center, Maastricht, The Netherlands.
Eur J Cardiothorac Surg
August 2022
Department of Surgery, Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Amsterdam, Netherlands.
Objectives: A minimally invasive lobectomy (MIL) is the standard treatment for stage I non-small cell lung cancer (NSCLC) in medically operable patients. Stereotactic ablative radiotherapy (SABR) is recommended for inoperable patients and has been proposed as a potential alternative for operable patients as well. Here, we present the results of a feasibility study in preparation for a nationwide retrospective cohort study, comparing outcomes between both treatment modalities.
View Article and Find Full Text PDFClin Exp Allergy
August 2021
Department of Dermatology/Allergology, University Medical Center Utrecht, University of Utrecht, Utrecht, The Netherlands.
Br J Anaesth
June 2021
Department of Anaesthesiology, Pharmacology, Intensive Care and Emergency Medicine, University Hospitals of Geneva, Geneva, Switzerland; University of Geneva, Geneva, Switzerland.
Background: Neonates and infants requiring anaesthesia are at risk of physiological instability and complications, but triggers for peri-anaesthetic interventions and associations with subsequent outcome are unknown.
Methods: This prospective, observational study recruited patients up to 60 weeks' postmenstrual age undergoing anaesthesia for surgical or diagnostic procedures from 165 centres in 31 European countries between March 2016 and January 2017. The primary aim was to identify thresholds of pre-determined physiological variables that triggered a medical intervention.
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