The disturbance suppression of magnetic levitation turbomolecular pumps is a critical problem in industrial applications. This work addresses the stability control of high-speed magnetic levitation turbomolecular pumps with shock-excited disturbance. A disturbance suppression method based on improved linear extended state observer is proposed to attenuate the impact of external low-frequency disturbing force on a magnetic levitation turbomolecular pump. Firstly, a linear extended state observer of an active magnetic bearing is obtained by analyzing the rotor dynamics model. Then, the detailed descriptions of external disturbance suppression method using linear extended state observers and adaptive notch filters are discussed for the system. The boundary condition of the parameters of the improved linear extended state observer is determined. The root loci of the closed-loop system with improved linear extended state observers is also investigated. Finally, simulation and experimental results on a magnetic levitation turbomolecular pump show the applicability of the proposed method. The results show that the proposed method can attenuate the rotor vibration displacement caused by impact by 46.9%.
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http://dx.doi.org/10.1016/j.isatra.2023.07.045 | DOI Listing |
Phys Rev Lett
December 2024
Laboratoire De Physique de l'École Normale Supérieure, ENS, PSL, CNRS, Sorbonne Université, Université de Paris, 24 rue Lhomond, 75005 Paris, France.
Electric quadrupole traps are a leading technology for suspending charged objects ranging in size from single protons to atomic and molecular ions, and even to nano- and micron-sized bodies. If the levitated objects' charge distribution contains multipoles, the time-dependent trapping fields can significantly impact its rotational motion. Here, we experimentally observe the transition from librational motion to a regime where a microparticle rotates in sync with the trap drive.
View Article and Find Full Text PDFJACC Heart Fail
December 2024
Brigham and Women's Hospital Heart and Vascular Center, Harvard Medical School, Boston, Massachusetts, USA.
Background: Prior analyses have suggested that a smaller left ventricular end-diastolic diameter (LVEDD) is associated with reduced survival following HeartMate 3 left ventricular assist device implantation.
Objectives: In this trial-based comprehensive analysis, the authors sought to examine clinical characteristics and association with the outcome of this specific relationship.
Methods: The authors analyzed the presence of LVEDD <55 mm among 1,921 analyzable HeartMate 3 patients within the MOMENTUM 3 (Multicenter Study of MagLev Technology in Patients Undergoing Mechanical Circulatory Support Therapy With HeartMate 3) trial portfolio, on endpoints of overall survival and adverse events at 2 years.
Artif Organs
December 2024
Department of Cardiac-, Thoracic-, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany.
Background: The study assesses the feasibility of the DuoCor BiVAS, a novel biventricular assist system integrating magnetic levitation technology.
Methods: In an acute large animal model involving five sheep, each received the DuoCor BiVAS without cardiopulmonary bypass. Hemodynamic and device parameters were monitored continuously for 1-h post-implantation.
Phys Rev Lett
November 2024
Laboratoire De Physique de l'École Normale Supérieure, École Normale Supérieure, PSL Research University, CNRS, Sorbonne Université, Université Paris Cité, 24 rue Lhomond, 75231 Paris Cedex 05, France.
Nuclear magnetic resonance (NMR) spans diverse fields from biology to quantum science. Employing NMR on a floating object could unveil novel possibilities beyond conventional operational paradigms. Here, we observe NMR within a levitating microdiamond using the nuclear spins of nitrogen-14 atoms.
View Article and Find Full Text PDFSci Rep
December 2024
School of Electrical Engineering and Automation, Jiangxi University of Science and Technology, Ganzhou, 341000, China.
Permanent magnet magnetic levitation (PMFL) system has the characteristics of zero-power levitation, strong load-carrying capacity and self-stabilization, so it has obvious advantages in the application of rail transportation and heavy-duty transmission and other fields. However, due to the lack of active control of electromagnetism and the existence of multi-point coupling, it is easily affected by external factors, and its dynamic characteristics and its complexity. This paper aims to reveal the levitation mechanism of permanent magnet magnetic levitation system and the coupling motion law of bogie by combining theoretical analysis and experimental verification.
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