Articles de revues : « Passive magnetic suspension »

1

Nguyen, V., J. Delamare et J. P. Yonnet. « A passive damper for magnetic suspension ». IEEE Transactions on Magnetics 30, n^o 6 (1994) : 4749–51. http://dx.doi.org/10.1109/20.334210.

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Zádor, István, Ádám Török, Pál Rácz et Istvan Vajda. « Green Energy from Road Vehicle Shock Absorber ». Materials Science Forum 792 (août 2014) : 287–92. http://dx.doi.org/10.4028/www.scientific.net/msf.792.287.

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It is still a difficult problem to solve for a suspension system simultaneously to hold the body of the car in comfort and to execute the requirements of other safety systems like ABS, ESP, steer-by-wire, etc systems. Passive suspension systems are unlikely to provide a solution, the introduction of semi-active suspensions in the practical use is necessary. A possible solution could be a permanent magnetic (PM) synchronous tube generator, which can operate as a controllable shock absorber parallel with energy recuperative operation. Designer software is realized, to calculate the geometrical and electrical parameters of permanent magnetic (PM) or high temperature superconductor (HTS) magnets for arbitrary vehicle suspension systems

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Zador, István, Ádám Török, István Vajda et László Palkovics. « OSCILLATION CONTROL OVER LIGHT DUTY CARS USING MAGNETIC SEMI-ACTIVE SHOCK ABSORBERS ». TRANSPORT 26, n^o 3 (5 octobre 2011) : 284–89. http://dx.doi.org/10.3846/16484142.2011.622357.

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The present vehicles on the road are equipped with an extended range of actuators, sensors and software controlling dynamics. It is still a difficult problem to solve for a suspension system simultaneously holding the body of the car in comfort and executing requirements imposed for other safety systems like ABS, ESP, steer-by-wire etc. Passive suspension systems are unlikely to provide a solution, and therefore the introduction of semi-active suspensions in practical use is necessary. A possible solution could be a permanent magnetic (PM) synchronous tube generator that can operate as a controllable shock absorber parallel with energy recuperative operation. Design software is realized to calculate geometrical and electrical parameters for arbitrary vehicle suspension systems.

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D’Angola, A., G. Carbone, L. Mangialardi et C. Serio. « Non-linear oscillations in a passive magnetic suspension ». International Journal of Non-Linear Mechanics 41, n^o 9 (novembre 2006) : 1039–49. http://dx.doi.org/10.1016/j.ijnonlinmec.2006.10.013.

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LeMarquand, Guy, et Jean‐Paul Yonnet. « A partially passive magnetic suspension for a discoidal wheel ». Journal of Applied Physics 64, n^o 10 (15 novembre 1988) : 5997–99. http://dx.doi.org/10.1063/1.342128.

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Bonisoli, E., et A. Vigliani. « Identification techniques applied to a passive elasto-magnetic suspension ». Mechanical Systems and Signal Processing 21, n^o 3 (avril 2007) : 1479–88. http://dx.doi.org/10.1016/j.ymssp.2006.05.009.

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Foong Soong, Ming, Rahizar Ramli, Ahmad Abdullah Saifizul et Mahdieh Zamzamzadeh. « Applicability of A Rotary Eddy Current Damper in Passenger Vehicle Suspension with Parallel Inerter ». International Journal of Engineering & ; Technology 7, n^o 3.17 (1 août 2018) : 76. http://dx.doi.org/10.14419/ijet.v7i3.17.16626.

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Numerous studies have proven that the performance of vehicle suspension can be benefited by an inerter in parallel to conventional spring-damper setup, yet its usability in passenger vehicle suspension is still limited by practical consideration in physical implementation. One way of achieving better physical implementation of the parallel inerter suspension layout is to exploit the inerter’s flywheel as a metallic conductor to integrate passive damping in the form of a rotary eddy current damper. However, the feasibility of eddy current damping in this specific application remains unknown. This study investigates the applicability of eddy current damping incorporated in an inerter in terms of the achievable damping rates as required in typical passenger vehicle suspensions. In the study, passive eddy current damping due to constant magnetic field around the flywheel of a mathematically designed inerter was computed through simulation, and the range of achievable damping rates due to parametric variations, for instance air gap and magnetic coverage, was evaluated. Results of the parametric analysis showed that the induced eddy current damping from a rack-and-pinion inerter’s flywheel, considering the designed inertance as prerequisite, was at least capable of achieving 1500 Nsm-1. As the achievable damping was within the range of suitable damping rates for typical passenger vehicles, rotary eddy current damper was deemed applicable in passenger vehicle suspension employing parallel inerter.

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Cao, Shinan, Pingjuan Niu, Wei Wang, Tiantian Zhao, Qiang Liu, Jie Bai et Sha Sheng. « Novel Magnetic Suspension Platform with Three Types of Magnetic Bearings for Mass Transfer ». Energies 15, n^o 15 (5 août 2022) : 5691. http://dx.doi.org/10.3390/en15155691.

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For ultra-precision, large stroke, and high start/stop acceleration, a novel magnetic suspension platform with three types of magnetic bearings is proposed. The structure and working principle of the novel platform are introduced. The passive magnetic bearings are used to compensate for the weight of the actuator. The repulsive force of the passive magnetic bearing model is established and analyzed. The Lorentz force-type magnetic bearings are used to provide driving force and rotational torque in the XY-plane. The driving force model and rotational torque model are established. The electromagnetic suspension bearing is used to provide driving force in the Z-axis and rotational torque along the X-axis and Y-axis. A novel Halbach magnetic array is designed to improve the magnetic flux density in the air gap. The finite element method is used to validate the force model, torque model, and magnetic flux density in the air gap. The results show that the maximum force of the passive magnetic bearing is 79 N, and the rotational torque stiffness is 35 N/A in the XY-plane and 78 N/A along the Z-axis. The driving force stiffness is 91 N/A in the XY-plane and 45 N/A along Z-axis.

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Linares, Henrique, Carlos Frajuca, Fabio S. Bortoli, Givanildo A. Santos et Francisco Y. Nakamoto. « Magnetic Suspension with Motorization to Measure the Speed of Gravity ». International Journal of Modern Physics : Conference Series 45 (janvier 2017) : 1760020. http://dx.doi.org/10.1142/s2010194517600205.

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This work aims to design a magnetic suspension for an experiment to measure gravitys velocity. Such device must rotate two objects symmetrically with the greatest mass and largest radius as possible, at the speed of [Formula: see text], which means this device falls into the high-speed machines category. The guidelines and solutions proposed in this paper constitute a contribution to this class of engineering problems and were based on an extensive literature search, contacts with experts, the tutors and author’s experience, as well as on experimental results. The main solution proposed is a hybrid bearing that combines a radial passive magnetic bearing with an axial sliding bearing, here called MPS (Magnetic Passive and Sliding) bearing.

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Falkowski, Krzysztof, Maciej Henzel, Paulina Kurnyta-Mazurek, Mariusz Janczewski et Mariusz Ważny. « Magnetic Suspension Technology for Electric Jet Engines ». Bulletin of the Military University of Technology 70, n^o 3 (30 septembre 2021) : 49–70. http://dx.doi.org/10.5604/01.3001.0015.8771.

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Reducing the emission of harmful compounds such as carbon dioxide and nitrogen oxides has been identified as a priority target in the European Union. Aviation is one of the main sources of pollution. The reduction of pollutant emissions can be achieved by the use of the electric jet engine. This type of a jet engine differs significantly from a kerosene-powered engine. The article presents the concept of an electric jet engine with the rotor that is magnetically suspended. Demonstrators of active and passive magnetic bearing technologies and bearingless electric motors, developed at the Avionics Department, are presented in the paper.

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Xu, Xiao Zhuo, Xiao Feng Qin et Xu Dong Wang. « Characteristics Analysis of a Novel Detent-Force-Based Magnetic Suspension System ». Advanced Materials Research 383-390 (novembre 2011) : 2644–48. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.2644.

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A novel Detent-force-based Magnetic Suspension System (DMSS) is presented. The topological structure and operating principle of DMSS are analyzed. The characteristics of the axial, radial force and magnetic field and torsion moment are studied with FEA method respectively. Simulation results show that the DMSS can generate larger levitation force than common levitation systems, and its levitation mode is a passive suspension in the axial direction and torsion without external control.

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Dai, Changming, Zhengyuan Liu, Yu Wang, Xiang Lin, Hui Liu et Bo Zhou. « Design and Optimization of a New Type of Magnetic Suspension Vibration Absorber for Marine Engineering ». Journal of Marine Science and Engineering 11, n^o 11 (30 octobre 2023) : 2070. http://dx.doi.org/10.3390/jmse11112070.

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The magnetic suspension damper, which is based on magnetic suspension technology, is receiving more and more attention from academics as active–passive hybrid damping technology develops. A new symmetric magnetic suspension structure is constructed in this study, and the accuracy of the simulation findings is confirmed by contrasting the output from finite element simulation with the theoretical formulations. On the basis of this, how the structure, size, and material of the electromagnet and armature affect the magnetic flux density, electromagnetic force, and suspension force is investigated. The structure optimization of the electromagnet and armature was performed in accordance with the simulation results, and a new symmetric magnetic suspension structure was produced. The results of the simulation demonstrate that DT4(electrical pure iron) is the ideal material for armatures and electromagnets. The reinforcing ring construction can be built up by the armature to increase suspension force. The suspension force output by the armature will be greatly increased when the size and placement of the reinforcing ring structure are right. The system stiffness adjustment range will expand at this point, enhancing the magnetic suspension damper’s functionality. This study offers novel perspectives for designing structures that reduce vibration and noise in various projects and serves as a guide to constructing magnetic suspension dampers.

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Falkowski, Krzysztof. « Second-Order Model of the Radial Passive Magnetic Bearing with Halbach's Array ». Solid State Phenomena 198 (mars 2013) : 400–405. http://dx.doi.org/10.4028/www.scientific.net/ssp.198.400.

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In the paper is presented model of the passive magnetic bearing. The response of bearing is approximate by second order model. There are presented the damping and stiffness coefficient of suspension. The coefficients derived from Biot-Savards law, Ohms law and Lorenzs force. There is presented loop with molecular current as a model of magnet, final formula of damping and stiffness coefficients and static characteristic of passive magnetic bearing.

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Song, Chun Sheng, et Ye Fa Hu. « Optimized Fuzzy Neural Networks Control of a Magnetic Suspension Vibration Isolation System ». Applied Mechanics and Materials 226-228 (novembre 2012) : 328–34. http://dx.doi.org/10.4028/www.scientific.net/amm.226-228.328.

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Active vibration isolation technology can overcome the defects of passive vibration isolation technology that the poor vibration isolation performance in low and resonant frequencies. Compared with other active vibration isolation technologies, magnetic suspension isolation technology has shown useful characteristics, such as wide response frequency range, fast response, high reliability and long-life. However, the control of MSVI is still one of the areas that require further investigation. This paper presents a Fuzzy Neural Networks(FNN) control algorithm for a magnetic suspension isolation vibration system, which is optimized by improved Genetic Algorithm(GA). The output force responses of the FNN and passive vibration isolation system under same excitation are simulated. The simulation results show that the fuzzy control system has much better performance in vibration isolation.

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Shen, Peng, Yiwen Wang, Yun Chen, Pengqiang Fu, Lijie Zhou et Lijia Liu. « Hydrodynamic Bearing Structural Design of Blood Pump Based on Axial Passive Suspension Stability Analysis of Magnetic–Hydrodynamic Hybrid Suspension System ». Machines 9, n^o 11 (27 octobre 2021) : 255. http://dx.doi.org/10.3390/machines9110255.

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Rotor suspension stability is one of the important performance indexes of a blood pump and the basis of determining whether the blood pump can be used in a clinic. Compared with the traditional magnetic suspension system, a single-winding, bearingless motor has the advantages of a compact structure, simple control system and low power consumption. In this pursuit, the present study aimed to envisage and design the magnetic suspension system coupled with a single-winding bearingless motor and permanent magnet bearings, establish the theoretical models of axial force and electromagnetic torque, and calculate the stiffness of the magnetic suspension system at the equilibrium point. Addressing the problem of the negative axial stiffness of the magnetic suspension system being negative, which leads to the instability of the suspension rotor, the hydrodynamic bearing structure was proposed and designed, and the critical stiffness to realize the stable suspension of the rotor was obtained based on the stability criterion of the rotor dynamics model. The optimal structural parameters of the hydrodynamic bearing are selected by integrating various factors based on the solution of the Reynolds equation and a stiffness analysis. Furthermore, the vibration experiment results proved that the blood pump rotor exhibited a good suspension stability, and the maximum offset under the impact external fluid was no more than 2 μm.

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Li, Qiang, Deng Feng Xu, Jin Chun Hu et Liu Hao. « A Low Frequency Permanent Magnet Passive Vibration Isolator ». Advanced Materials Research 586 (novembre 2012) : 328–36. http://dx.doi.org/10.4028/www.scientific.net/amr.586.328.

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Magnetic suspension vibration isolators have attracted significant attention in the field of semiconductor industry and high precision equipments. However, it is impossible to levitate an object by only permanent magnet due to instability of permanent magnets. It needs a guide device or active control to hold the magnetic suspension passive vibration isolator (MSPVI) at equilibrium position. In order to overcome the instability of the permanent magnets, the linear bearing, rubber O-ring and rubber membrane are applied in the MSPVI. The transmissibility of the MSPVI was calculated and subsequently measured. The experimental results show that the MSPVI can achieve low natural frequency with the help of the rubber membrane which is superior to the linear bearing and o-ring. Beside, the vibration isolating performance of the MSPVI is measured. The experimental results reveal that the MSPVI achieves the lowest resonant frequency when the load capacity of the MSPVI reaches maximum value.

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Seto, Kazuto. « Special Issue on Advanced Vehicle Dynamics and, Control ». Journal of Robotics and Mechatronics 7, n^o 4 (20 août 1995) : 273. http://dx.doi.org/10.20965/jrm.1995.p0273.

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Various attempts have been made from olden days on vehicles for better riding comfort and for improved maneuverability. Past vehicles have achieved vibration isolation performance, which relaxes impact from road surfaces, by means of link mechanisms and passive suspensions consisting of springs and dampers, as well as basic motion performance such as running, turning, and stopping. However, as far as passenger cars are concerned, a passive suspension has its own limitation, and the contradiction that if riding comfort is to be improved at low speeds, the maneuverability during high-speed operations becomes bad has not been solved. Demand of users has become stronger and stronger for vehicles which satisfy riding comfort and maneuverability at the same time. Moreover, as far as trains are concerned, the past technology has increased the vibration of trains as they are operated at higher speeds; thus a drop in riding comfort has been a cause for preventing high-speed operations. Nevertheless, in line with progress in mechatronic technology, active suspensions have been adopted aggressively in automobiles and trains in recent years, and attempts have been started for improving both riding comfort and maneuverability to satisfy demand of users. Some passenger cars have already appeared which are equipped with an active suspension. A similar trend is found in the case of trains; by the introduction of active suspensions, operations of trains on conventional lines at higher speeds are being started. Under these circumstances, this special issue has been created. Although high performance in vehicles may be achieved by means of active suspensions, the problem of increased energy consumption has become a serious issue, which has been brought to the fore with the bursting of the bubble. This problem seems to be solved by saying how effectively semi-active suspensions may be realized. In this special issue, new trends have been taken up, such as vehicle dynamics, design theory on active suspension systems, reduction of engine vibration by optimum design of hydraulic engine mounts, design of control systems for neural networks of semi-active suspension systems, control of variable structures of suspension systems, predictive control, magnetic levitation suspension, etc. It is hoped that these articles will be useful in future research.

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Jiang, Weikang, Yuanyuan Song, Yongming Xu, Ran Zhou, Feng Sun et Xiaoyou Zhang. « Energy-Harvesting Characteristics of a Dual-Mode Magnetic Suspension for Vehicles : Analysis and Experimental Verification ». Actuators 11, n^o 12 (3 décembre 2022) : 363. http://dx.doi.org/10.3390/act11120363.

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The advantages of the proposed dual-mode magnetic suspension are it having a high level of safety and a compact structure compared with the previous studies. However, the structure parameters can affect the energy harvesting of the suspension system. Therefore, this paper aims to analyze the energy-harvesting characteristics of the proposed dual-mode magnetic suspension. Firstly, the structure and working principle of the proposed suspension are introduced. Then, the influences of the various parameters for the actuator on the energy regeneration characteristics are analyzed by the finite element method, such as the magnetic ring, the fixed plug thickness, the heat dissipation, and the air gap, and the actuator parameters are defined by the orthogonal analysis method. Furthermore, the numerical results of the energy harvesting are calculated. Finally, the vibration experimental setup is manufactured, and the simulation analysis is verified by the experiment. The results demonstrate that the excitation amplitude is 3.1 mm, the frequency is 18 Hz, and the maximum induced EMF is 8.8 V. Additionally, compared with passive suspension, the energy harvesting of the proposed suspension has been verified in the laboratory, which lays the foundation for the design and analysis of the dual-mode magnetic suspension in a real vehicle.

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Diez-Jimenez, Efren, Cristina Alén-Cordero, Roberto Alcover-Sánchez et Eduardo Corral-Abad. « Modelling and Test of an Integrated Magnetic Spring-Eddy Current Damper for Space Applications ». Actuators 10, n^o 1 (2 janvier 2021) : 8. http://dx.doi.org/10.3390/act10010008.

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We present the design, manufacturing, and dynamical characterization of a mechanical suspension made by a passive magnetic spring and an eddy current damper integrated into a single device. Three configurations with 2, 3, and 4 permanent magnets axially distributed with opposite polarizations are designed, simulated, manufactured, and tested. Stiffness of 2410, 2050, 2090 N/m and damping coefficient of 5.45, 10.52 and 17.25 Ns/m are measured for the 2-, 3-, and 4-magnets configurations, respectively. The magnetic suspension provides good mechanical properties combined with excellent cleanness and high reliability, which is very desirable in mechanical systems for space applications.

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Qian, Kun Xi, Z. H. Xu et H. Wang. « Effects of Rotational Inertia and Bearing Force on Stability of Permanent Maglev Rotator ». Applied Mechanics and Materials 150 (janvier 2012) : 50–56. http://dx.doi.org/10.4028/www.scientific.net/amm.150.50.

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The authors’ former works demonstrated that a passive magnetic (PM) rotator supported merely by PM bearings has a minimal speed, above which it can stabilize its equilibrium, under the function of a so-called Gyro-effect. It is unclear, however, by which factors is this minimal speed determined. This paper investigated the factors affecting the minimal stable speed of permanent maglev rotator, namely, the rotating inertia and PMB force. Two novel permanent maglev turbine models were designed: Model A---one stator and three rotors which have the same size but different rotational inertias; Model B---one rotor and one stator, but the stator has been devised with three different passive magnetic bearings: 1. a pair of small magnetic rings; 2. a pair of big magnetic rings; and 3. both of the two pairs of magnetic rings. Four Hall sensors distributed evenly at the turbine’s stator were used to detect the rotor’s eccentricity, and the speed sensor measured rotating speed. The calculated models of rotor’s eccentricity were established respectively for the two turbine models; the rotor’s eccentricity measuring system was built up and the rotor’s eccentricity of the two turbines was measured. The experimental data demonstrated that the rotational inertia of three rotors in the model A is 6.293×10-5 kg•m2, 1.074×10-4 kg•m2 and 2.081×10-4 kg•m2 respectively, and the corresponding minimal speed for suspension are 4597rpm, 3030rpm and 2222rpm respectively; in the model B, the magnetic force between the stator and rotor in the three cases is 92.12N, 123.48N, 212.66N respectively, corresponding to the minimal speed for suspension---3730rpm, 3120rpm and 2195rpm respectively. The results exhibited that same as the permanent maglev heart pump, permanent maglev turbines also have gyroscopic effect, which makes the rotors maintain stable suspension. And the minimal speed for suspension has a negative correlation with the rotor’s rotational inertia, namely, the bigger the inertia of the rotor, the smaller the required speed for suspension; the minimal speed for suspension also has a negative correlation with the magnetic force between the stator and rotor, that is, the larger the magnetic force, the smaller the rotating speed for suspension. Smaller minimal speed means better stability of the system, thereafter larger inertia or larger bearing force means better stability; besides, larger difference between minimal speed and performance speed of the rotator means better stability, it’s suggested permanent maglev be applied in high speed rotary machines.

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Tozoni, O. V. « Gas Gun Accelerator Based on Passive Magnetodynamic Suspension ». IEEE Transactions on Magnetics 40, n^o 3 (mai 2004) : 1642–49. http://dx.doi.org/10.1109/tmag.2004.826614.

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Detoni, JG. « Progress on electrodynamic passive magnetic bearings for rotor levitation ». Proceedings of the Institution of Mechanical Engineers, Part C : Journal of Mechanical Engineering Science 228, n^o 10 (17 novembre 2013) : 1829–44. http://dx.doi.org/10.1177/0954406213511798.

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Electrodynamic suspension exploits repulsive forces due to eddy currents to produce positive stiffness by passive means, without violating the Earnshaw stability criterion. Systems employing this principle to levitate a rotor radial and/or axial degrees of freedom are called electrodynamic bearings (EDBs). Since the eddy currents can be induced either by using alternating current supplied electromagnets or by the relative motion between a conductor and a constant magnetic field, the research on EDBs has developed many different configurations. The present paper reviews the literature on electrodynamic passive magnetic bearings to analyze the evolution of this technology toward completely passive, stable, rotor levitation, and to compare the EDBs performance with other common magnetic bearing technologies. Radial and axial EDB technologies are reviewed attempting to create an organized connection between the works and to discuss some critical issues that still preclude the use of EDBs in industrial applications.

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Gao, Xiang, Junchuan Niu, Ruihao Jia et Zhihui Liu. « Influential characteristics of electromagnetic parameters on self-powered MR damper and its application in vehicle suspension system ». Proceedings of the Institution of Mechanical Engineers, Part K : Journal of Multi-body Dynamics 234, n^o 1 (27 août 2019) : 38–49. http://dx.doi.org/10.1177/1464419319870338.

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In order to reuse the energy dissipated by magneto-rheological (MR) damper, a self-powered MR damper is designed and analyzed theoretically. The main thrust of this work is establishing the mechanical-electromagnetic coupling model of quarter vehicle suspension based on self-powered MR damper, whilst the energy conversion efficiency of self-powered MR damper with electromagnetic parameters changing is investigated. The magnetic circuit model is formulated firstly. The influence of electromagnetic parameters on current in MR damper is analyzed systemically in frequency domain. A multi-objective optimization method is performed to determine the electromagnetic parameters. Subsequently a quarter vehicle suspension system with self-powered MR damper is introduced. The mechanical-electromagnetic coupling model is established. The frequency response function is derived under random road excitation. The vibration isolation capability of the proposed quarter vehicle suspension system is addressed in time and frequency domain respectively. Compared to passive control, the amplitude of sprung mass velocity, acceleration and transmissibility are reduced by 51%, 78% and about 10 dB in time and frequency domain respectively. Finally the energy conversion efficiency of self-powered MR damper with magnetic parameters changing under random road excitation is discussed. The vibration isolation performance of self-powered MR damper is more effective than passive control, especially in resonance range of the suspension system.

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Vataev, Andrew S., Olga A. Dedova et Victor V. Nikitin. « Efficiency of ferromagnetic shielding of superconducting coils of high-speed maglev crew ». Modern Transportation Systems and Technologies 9, n^o 2 (30 juin 2023) : 19–32. http://dx.doi.org/10.17816/transsyst20239219-32.

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Background: Magnetic levitation transport with combined traction, suspension and guidance systems based on superconducting coils (SCC) allows reaching speeds of up to 500600 km/h with a very significant (up to 150200 mm) air gap, which is an important factor in ensuring the safety of high-speed transportation. However, SCC are a source of strong external magnetic fields, which, in conditions of limited crew dimensions, can have a harmful effect on both passengers and on-board auxiliary equipment. Aim: to analyze the external magnetic fields of the SCC systems for traction, suspension and direction of maglev vehicles and the effectiveness of ferromagnetic screens as a means of ensuring the electromagnetic safety of passengers and the electromagnetic compatibility of the SCC with other onboard equipment. Materials and methods: to achieve this goal, methods of analytical and numerical modeling of the magnetic fields of the SCC using modern software packages were used. As a prototype of the combined magnetic system of traction, suspension and direction, the system of the MLX-L0 maglev vehicle, which is undergoing pilot commercial operation at the Yamanashi test line (Japan), was adopted. Results: it is shown that the value of the external magnetic fields of the SCC of the traction and guiding systems in the passenger cabin of the prototype crew exceeds the maximum permissible levels established by domestic and foreign regulatory documents, both without shielding and with passive shielding with flat steel sheets. Conclusion: passive shielding of the SCC with steel sheets, including multilayer ones, does not provide the required reduction in the level of external magnetic fields for a given vehicle dimensions.

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Kustosz, R., I. Altyntsev, M. Darlak, T. Wierzchoń, M. Tarnowski, M. Gawlikowski, M. Gonsior et M. Kościelniak-Ziemniak. « The Tin Coatings Utilisation As Blood Contact Surface Modification In Implantable Rotary Left Ventricle Assist Device Religaheart Rot ». Archives of Metallurgy and Materials 60, n^o 3 (1 septembre 2015) : 2253–60. http://dx.doi.org/10.1515/amm-2015-0371.

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Abstract Constructions of the mechanical-bearingless centrifugal blood pumps utilize different types of non-contact physical bearings, which allows to balance the forces that have an impact on the pump impeller, stabilizing its position in the pump house without wall contact. The paper presents investigations of the hybrid (passive magnetic bearings and hydrodynamic bearings) suspension system for the centrifugal blood pump. Numerical simulations were used to evaluate the hydrodynamic bearing lifting force and magnetic bearing forces interaction. An important aspect of rotor suspension system design was the nominal gap in hydrodynamic bearing area in order to reduce the blood damage risk in this region. The analyses results confirmed that for a small diameter centrifugal pump, the nominal operating hydrodynamic bearing gap could be established within the range from 0.033 to 0.072 mm.

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Shinshi, Tadahiko, Daisuke Shimizu, Kazuhide Kodeki et Kazuhiko Fukushima. « A Fast Steering Mirror Using a Compact Magnetic Suspension and Voice Coil Motors for Observation Satellites ». Electronics 9, n^o 12 (25 novembre 2020) : 1997. http://dx.doi.org/10.3390/electronics9121997.

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Fast steering mirrors (FSMs) are used to correct images observed by satellites. FSMs need to have large apertures and realize high precision and the positioning of the mirror in the tip-tilt and axial directions needs to be highly precise and highly responsive in order to capture large-scale, high-resolution images. An FSM with a large-diameter mirror supported by a compact magnetic suspension and driven by long-stroke voice coil motors (VCMs) is proposed in this paper. The magnetic suspension and VCM actuators enable the mirror to be highly responsive and to have long-range movement in the tip-tilt and axial directions without friction and wear. The magnetic suspension is a hybrid that has active control in the lateral directions and passive support in the tip-tilt and axial directions. An experimental FSM with an 80 mm diameter dummy mirror was fabricated and tested. The mirror’s driving ranges in the tip-tilt and axial directions were ±20 mrad and ±500 μm, respectively. Furthermore, the servo bandwidths in the tip-tilt and axial directions were more than 1 kHz and 200 Hz, respectively.

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Zhou, Ran, Yuanyuan Song, Junjie Jin, Fangchao Xu, Feng Sun, Lijian Yang et Mingyin Yan. « Dynamic Performance of a Magnetic Energy-Harvesting Suspension : Analysis and Experimental Verification ». Actuators 12, n^o 8 (27 juillet 2023) : 308. http://dx.doi.org/10.3390/act12080308.

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The advantages of the proposed novel magnetic energy-harvesting suspension (MEHS) are high safety, compact structure and convenient maintenance, compared with the previous studies. However, the force generated by the energy harvester with harvesting energy can affect the motion of the mechanical system. Therefore, this paper aims to analyze the ride comfort and road handling of the MEHS, and investigates the dynamic performance of the MEHS. Firstly, the structure and the working principle of the MEHS are illustrated and introduced, and the dynamic mechanism of the quarter-vehicle with the MEHS is revealed and investigated. Secondly, the effects of the electromechanical coupling coefficient and external load resistance on the dynamic performance are investigated by numerical calculation. An experimental setup is established to verify the dynamic performance of the proposed MEHS. According to the experimental results, the dynamic performance of the suspension is contradictory with the increase of the external load resistance at the periodic frequency 7 Hz. And compared with the passive suspension, the dynamic performance of the MEHS is changed at various excitations, in which the sprung displacement and relative dynamic load of the tire of MEHS at the periodic frequency 3.3 Hz are reduced by 39.45% and 41.18%, respectively. Overall, the external load resistance of the proposed MEHS can be utilized to realize the variable damping of the suspension system and reduce the effect of vibration on the suspension system at the resonance frequency. And the dynamic performance has been verified in the laboratory, which lays the foundation for the dynamic analysis in a real vehicle.

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Martynenko, Gennadii. « APPLICATION OF NONLINEAR MODELS FOR A WELL-DEFINED DESCRIPTION OF THE DYNAMICS OF ROTORS IN MAGNETIC BEARINGS ». EUREKA : Physics and Engineering 3 (31 mai 2016) : 3–12. http://dx.doi.org/10.21303/2461-4262.2016.00074.

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A research report has been submitted. It deals with implementing a method for a mathematical description of the nonlinear dynamics of rotors in magnetic bearings of different types (passive and active). The method is based on Lagrange-Maxwell differential equations in a form similar to that of Routh equations in mechanics. The mathematical models account for such nonlinearities as the nonlinear dependencies of magnetic forces on gaps in passive and active magnetic bearings and on currents in the windings of electromagnets; nonlinearities related to the inductances in coils; the geometric link between the electromagnets in one AMB and the link between all AMBs in one rotor, which results in relatedness of processes in orthogonal directions, and other factors. The suggested approach made it possible to detect and investigate different phenomena in nonlinear rotor dynamics. The method adequacy has been confirmed experimentally on a laboratory setup, which is a prototype of a complete combined magnetic-electromagnetic suspension in small-size rotor machinery. Different variants of linearizing the equations of motion have been considered. They provide for both linearization of restoring magnetic or electromagnetic forces in passive and active magnetic bearings, and exclusion of nonlinear motion equation terms. Calculation results for several linearization variants have been obtained. An appraisal of results identified the drawbacks of linearized mathematical models and allowed drawing a conclusion on the necessity of applying nonlinear models for a well-defined description of the dynamics of rotor systems with magnetic bearings.

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Shiao, Yao Jung, et Yao Kuan Huang. « Design of a Novel Damping-Controllable Damper for Suspension Systems ». Advanced Materials Research 338 (septembre 2011) : 622–25. http://dx.doi.org/10.4028/www.scientific.net/amr.338.622.

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Conventional oil dampers are non-controllable passive dampers because the viscosity of the fluid used is not wide-range variable. By using magneto-rheological fluid (MRF), MRF damper has excellent performance for variable-damping applications. Due to the single-coil design in the general MRF damper, the obtained damping from MR effect is not quite large. This research provides a high-damping MRF damper by adopting multi-pole coil and special polarization configuration. The simulated results show that the new MRF damper has good performance in the magnetic field and damping. Compared with a similar-size general single-coil MRF damper, this new MRF damper can get 47% higher performance under the same operating conditions.

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Kublin, Tomasz, Lech Grzesiak, Paweł Radziszewski, Marcin Nikoniuk et Łukasz Ordyszewski. « Reducing the Power Consumption of the Electrodynamic Suspension Levitation System by Changing the Span of the Horizontal Magnet in the Halbach Array ». Energies 14, n^o 20 (12 octobre 2021) : 6549. http://dx.doi.org/10.3390/en14206549.

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In high-speed magnetic railways, it is necessary to create the forces that lift the train. This effect is achieved by using active (EMS) or passive (EDS) magnetic systems. In a passive system, suspension systems with permanent magnets arranged in a Halbach array can be used. In this paper, an original Halbach array with various alternately arranged horizontally and vertically magnetized magnets is proposed. Correctly selected geometry allows us to obtain higher values of levitation forces and lower braking forces in relation to a system with identical horizontally and vertically magnetized elements. The effect of such a shape of the magnetic arrangement is the reduction of instantaneous power consumption while traveling due to the occurrence of lower braking forces. In order to perform a comparative analysis of the various geometries of the Halbach array, a simulation model was developed in the ANSYS Maxwell program. The performed calculations made it possible to determine the optimal dimensions of horizontally and vertically magnetized elements. The results of calculations of instantaneous power savings for various cruising speeds are also included.

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Chauhan, Nileshkumar D., et Dipal Patel. « Design Optimization of Flow Mode Magnetorheological Damper ». Applied Mechanics and Materials 877 (février 2018) : 403–8. http://dx.doi.org/10.4028/www.scientific.net/amm.877.403.

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To control the vibrations with passive suspension system having limitation with constant damping force. By using smart material like magnetorheological fluid, it is possible to control the damping performance of suspension system using current variations in magnetic coil. Applications of this kind of damper are in front loaded washing machine and damper use in driver seat of heavy duty vehicles. Mainly flow mode MR damper is most commonly used damper for these two applications. This paper represents theoretical model and optimized design of flow mode MR damper. For any kind of MR damper design of magnetic coil is play very vital role. So for this paper mainly includes the design of coil and different parameters like number of coil distance between two coil current passing from the coil is consider for design and optimization using FEMM software. This work also includes the theoretical study of MR damper characteristics with force-displacement and force velocity plot with change in piston diameter and fluid gap.

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Mei, Hua Ping, Hao Yue Tian et Shuan Huang. « Recent Study on the Passive and Active Vibration Isolators ». Applied Mechanics and Materials 494-495 (février 2014) : 491–96. http://dx.doi.org/10.4028/www.scientific.net/amm.494-495.491.

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The vibration isolators have witnessed significant developments due to pressing demands for high resolution metrology and manufacturing, optical, physical and chemical experiments. In the view of these requirements, the engineers and physicists have exploited different types of vibration isolators. This paper firstly presents the recent developments on the passive vibration isolators. It finds that the passive vibration isolators can constrain the high frequency oscillation. The active control is the efficient method to cancel the low frequency vibration. Then, the paper is concerned with the recent advances on the active vibration isolator. The appropriate actuator, sensor and advanced control method are the key component of the active vibration isolator to enhance their vibration isolation properties. Finally, the author proposes that the magnetic suspension vibration isolator is a future research direction in the field of the vibration isolation.

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Fabbri, Massimo, Pier Luigi Ribani et Davide Zuffa. « Design and testing of a magnetic suspension for a 90° horizontal bend conveyor ». COMPEL : The International Journal for Computation and Mathematics in Electrical and Electronic Engineering 34, n^o 1 (5 janvier 2015) : 380–96. http://dx.doi.org/10.1108/compel-02-2014-0049.

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Purpose – A conveyor device is studied with the aim to reduce the friction between the inner surface of the beam and the chain. The lower is the friction between the chain and the beam, the lower is the surface wear. The magnetic repulsion force among permanent magnets (PMs) placed on the beam and on the chain is utilized to reduce friction. The paper aims to discuss these issues. Design/methodology/approach – The considered magnetic suspension is realized with PMs in repulsive configuration; it is designed by solving a constrained optimization problem, with reference to the geometry of the 90° horizontal bend FlexLink WL322 conveyor. Flux density field and its gradient are evaluated using volume integral equation method, allowing to calculate the forces acting on the chain and the stiffness of the magnetic suspension. Findings – The magnetic suspension prototype was manufactured and tested. The experimental and calculated values of the forces acting on the chain compares well. A stable horizontal equilibrium of the chain was obtained during both static and dynamical tests. Research limitations/implications – The quasi-static model used neglects the dynamical interactions among the elements of the chain, the PMs and loads weight during motions and the eddy current losses in the aluminium beam. However the dynamical tests on the prototype show that the chain motion is regular up to the nominal velocity all along the conveyor with the exception of the trailing edge of the 90° curve. Practical implications – The tests on the prototype show the possibility of a removal or at least a reduction of the friction force between the chain and the inner side of the beam by means of a passive magnetic suspension. As a consequence a reduction of noise and vibrations and an increase of the mean-time-to-failure is expected. Originality/value – Prototype testing shows that the unavoidable vertical instability of the magnetic forces has no practical consequence since, reducing the allowed vertical gap, the chain is stabilized by the gravitational force.

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Wang, Yimei, Hossein Vatandoost et Ramin Sedaghati. « Development of a Novel Magneto-Rheological Elastomer-Based Semi-Active Seat Suspension System ». Vibration 6, n^o 4 (29 septembre 2023) : 777–95. http://dx.doi.org/10.3390/vibration6040048.

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Human operators in the transportation sector are exposed to whole-body vibration (WBV) while driving. Occupational exposure to WBV, predominant at low frequencies (<20 Hz), has been linked to spinal injuries and reduced functioning. This study aims at the design development of a novel semi-active seat suspension system featuring magneto-rheological elastomers (MREs) to mitigate the WBV. The proposed suspension system allows a greater range of strokes, while ensuring the MRE remains within an acceptable level of deformation. Several MRE samples were fabricated and characterized under shear mode. Afterward, a field- and frequency-dependent phenomenological model was developed to predict the viscoelastic properties of MREs as functions of both the excitation frequency and applied magnetic field. The MRE material model was subsequently used to design and optimize an adaptive seat suspension system incorporating a C-shaped MRE-based isolator in parallel and series with passive springs. The proposed adaptive seat suspension system demonstrated a frequency shift of 29% by increasing the applied current from 0 to 2 A. Finally, a 6-DOF lumped parameter model of a seated human subject combined with the proposed semi-active suspension system featuring the MRE isolator has been formulated to investigate the vibration transmissibility from the floor to the subject’s head.

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Li, Dengfeng, et Hector Martin Gutierrez. « Quasi-Sliding Mode Control of a High-Precision Hybrid Magnetic Suspension Actuator ». Journal of Robotics and Mechatronics 25, n^o 1 (20 février 2013) : 192–200. http://dx.doi.org/10.20965/jrm.2013.p0192.

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A novel 1-DOF hybrid magnetic suspension actuator for precise motion control is presented. The actuator is designed to achieve sub-micron positioning accuracy over a range of motion in excess of 1000 µm while avoiding large nominal levitation currents and iron core saturation. The proposed passive push-active pull configuration offers precise motion control with moderate actuator effort when a payload is to be accurately suspended over a large range of travel. The proposed actuator can be used modularly to control multiple axes of motion in a multi-DOF positioning application that requires millimeter-range travel with submicron accuracy. A Quasi-Sliding Mode controller (QSM) is presented in which the sliding mode dynamics are directly designed, as opposed to the typical Lyapunov function approach that is solely based on stability. Since full knowledge of the state vector is required, a nonlinear high-gain observer was also designed and implemented. Performance of the QSM algorithm in controlling the proposed actuator is compared to that of a PID controller with standard feedback linearization. Several experiments are conducted to demonstrate both the positioning and tracking capabilities of the proposed actuator. The proposed QSM method shows better transient performance than the standard PID feedback linearization approach. QSM also shows better tracking performance, which is highly desirable in systems in which fast and accurate motion control along a desired path is critical.

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Wang, Liang, Xiaoyan Tang, Zhong Yun et Chuang Xiang. « Analysis of a Novel Magnetic-Hydrodynamic Double Levitated Motor for an Implantable Axial Flow Blood Pump ». Shock and Vibration 2020 (10 décembre 2020) : 1–15. http://dx.doi.org/10.1155/2020/8833994.

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This paper presents a novel design for a bearingless axial flow blood pump based on the magnetic-hydrodynamic double levitated concept. In the axial direction, the magnetic levitation system consisted of two pairs of permanent magnet rings offsets the force of fluid. The hydrodynamic shell mounted on the impeller rotor is designed for generating dynamic pressure, which can balance the radial force like gravity when the blood pump is working. Because of the unsteady force and torque acting on the rotor and the passive suspension, the position of the rotor is not steady. The suspension force, stiffness, and torque of the rotor are calculated by the theoretical method and finite element method. Then, the dynamics of the rotor are analyzed. Arrangements of Hall-effect sensors with the corresponding data acquisition system which can measure the axial displacement of the rotor are explained. The sensorless drive control system for the blood pump is described too. With a prototype pump, an external circulation experiment system is built and then the axial and radial displacements of the rotor are measured by using Hall-effect sensors and the laser vibrometer under different working conditions.

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Aberturas, Susana, Juan Diego Aguilera, José Luis Olazagoitia, Miguel Ángel García et Antonio Hernando. « Mathematical Analysis of the Electromotive Induced Force in a Magnetically Damped Suspension ». Mathematics 12, n^o 7 (27 mars 2024) : 1004. http://dx.doi.org/10.3390/math12071004.

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This study explores the advanced mathematical modeling of electromagnetic energy harvesting in vehicle suspension systems, addressing the pressing need for sustainable transportation and improved energy efficiency. We focus on the complex challenge posed by the non-linear behavior of magnetic flux in relation to displacement, a critical aspect often overlooked in conventional approaches. Utilizing Taylor expansion and Fourier analysis, we dissect the intricate relationship between oscillation and electromagnetic damping, crucial for optimizing energy recovery. Our rigorous mathematical methodology enables the precise calculation of the average power per cycle and unit mass, providing a robust metric for evaluating the effectiveness of energy harvesting. Further, the study extends to the practical application in a combined system of passive and electromagnetic suspension, demonstrating the real-world viability of our theoretical findings. This research not only offers a comprehensive solution for enhancing vehicle efficiency through advanced suspension systems but also sets a precedent for the integration of complex mathematical techniques in solving real-world engineering challenges, contributing significantly to the future of energy-efficient automotive technologies. The cases reviewed in this article and listed as references are those commonly found in the literature.

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Kim, Su Deok, Seo Woo Song, Dong Yoon Oh, Amos Chungwon Lee, Jeong Woo Koo, Taehun Kang, Min Chang Kim et al. « Microspinning : Local Surface Mixing via Rotation of Magnetic Microparticles for Efficient Small-Volume Bioassays ». Micromachines 11, n^o 2 (7 février 2020) : 175. http://dx.doi.org/10.3390/mi11020175.

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The need for high-throughput screening has led to the miniaturization of the reaction volume of the chamber in bioassays. As the reactor gets smaller, surface tension dominates the gravitational or inertial force, and mixing efficiency decreases in small-scale reactions. Because passive mixing by simple diffusion in tens of microliter-scale volumes takes a long time, active mixing is needed. Here, we report an efficient micromixing method using magnetically rotating microparticles with patterned magnetization induced by magnetic nanoparticle chains. Because the microparticles have magnetization patterning due to fabrication with magnetic nanoparticle chains, the microparticles can rotate along the external rotating magnetic field, causing micromixing. We validated the reaction efficiency by comparing this micromixing method with other mixing methods such as simple diffusion and the use of a rocking shaker at various working volumes. This method has the potential to be widely utilized in suspension assay technology as an efficient mixing strategy.

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Li, Zhongxing, Chenlai Liu, Xinyan Song et Chengchong Wang. « Vibration suppression of hub motor electric vehicle considering unbalanced magnetic pull ». Proceedings of the Institution of Mechanical Engineers, Part D : Journal of Automobile Engineering 235, n^o 12 (22 mars 2021) : 3185–98. http://dx.doi.org/10.1177/09544070211004507.

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For the hub motor electric vehicle (HM-EV), the drive motor is directly integrated with the wheel. The unbalanced magnetic pull (UMP) of hub motor would be generated by magnet gap deformation under road surface roughness excitation. The longitudinal and vertical dynamic performances of the HM-EV system are therefore deteriorated. Firstly, to analyze and optimize the longitudinal and vertical dynamic performance of the HM-EV system, a new ten-degree-of-freedom mathematical quarter HM-EV system model equipped with air suspension model, permanent magnet brushless direct current (PM BLDC) hub motor model and rigid ring tire model is proposed. The UMP of PM BLDC hub motor is taken into consideration in this model. A HM-EV system model validation test bench is constructed. The accuracy of the model is verified by experiment. Secondly, based on quarter HM-EV system model, the BP neural network is adopted to calculate the longitudinal and vertical UMP. The relative error between results calculated by BP neural networks and electromagnetic formula is less than 5% and root-mean-square error (RMSE) is less than 2. With proposed BP neural networks calculation method, UMP calculation time is shortened by 70.3%. Finally, the adjustable force is introduced and model predictive control (MPC) method is used to suppress the longitudinal and vertical vibration of HMEV system. Two control methods, namely model predictive control (MPC) and constrained optimal control (COC) are proposed. The simulation results show that by applying MPC, the RMS value of evaluation indexes are decreased by 17.21%–44.10% respectively, which is better than COC (−14.42%–17.21%). With MPC, longitudinal and vertical vibration are suppressed. Comparison of two UMP calculation methods with MPC controller is conducted. The relative errors of evaluation indexes are within 3.85%. Therefore, the driving safety and riding comfort of the HM-EV are improved compared to the passive suspension and COC active suspension.

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Luong, Quoc Viet, Dae-Sung Jang et Jai-Hyuk Hwang. « Intelligent Control Based on a Neural Network for Aircraft Landing Gear with a Magnetorheological Damper in Different Landing Scenarios ». Applied Sciences 10, n^o 17 (28 août 2020) : 5962. http://dx.doi.org/10.3390/app10175962.

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A typical oleo-pneumatic shock-absorbing strut (classic traditional passive damper) in aircraft landing gear has a metering pin extending through the orifice, which can vary the orifice area with the compression and extension of the damper strut. Because the metering pin is designed in a single landing condition, the traditional passive damper cannot adjust its damping force in multiple landing conditions. Magnetorheological (MR) dampers have been receiving significant attention as an alternative to traditional passive dampers. An MR damper, which is a typical semi-active suspension system, can control the damping force created by MR fluid under the magnetic field. Thus, it can be controlled by electric current. This paper adopts a neural network controller trained by two different methods, which are genetic algorithm and policy gradient estimation, for aircraft landing gear with an MR damper that considers different landing scenarios. The controller learns from a large number of trials, and accordingly, the main advantage is that it runs autonomously without requiring system knowledge. Moreover, comparative numerical simulations are executed with a passive damper and adaptive hybrid controller under various aircraft masses and sink speeds for verifying the effectiveness of the proposed controller. The main simulation results show that the proposed controller exhibits comparable performance to the adaptive hybrid controller without any needs for the online estimation of landing conditions.

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Li, Weihua, Xianzhou Zhang et Haiping Du. « Development and simulation evaluation of a magnetorheological elastomer isolator for seat vibration control ». Journal of Intelligent Material Systems and Structures 23, n^o 9 (6 février 2012) : 1041–48. http://dx.doi.org/10.1177/1045389x11435431.

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Driver fatigue is one of the leading factors contributing to road crashes. Environmental stress, such as unwanted seat vibration, is a key contributor to fatigue. This article presents the design and development of a magnetorheological elastomer isolator for a seat suspension system. By altering the magnetorheological elastomer isolator’s stiffness through a controllable magnetic field and selecting suitable control strategy, the system’s natural frequency can be changed to avoid resonance, which consequently reduce the vehicle’s vibration energy input to seat, and thus suppress the seat’s response. Experimental results show that the developed magnetorheological elastomer isolator is able to reduce vibration more when compared with the passive isolation system, indicating the significant potential of its application in vehicle seat vibration control.

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Hassan, Hiba, Ali A. Salman, Mohammed A. Munshid et Abdulhadi Al-Janabi. « Passive Q-switching using Lead Sulfide suspension as a saturable absorber in 1.5 μm region ». Optical Fiber Technology 52 (novembre 2019) : 101969. http://dx.doi.org/10.1016/j.yofte.2019.101969.

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Kim, Hwan-Choong, Yu-Jeong Shin, Wonhee You, Kyu Chul Jung, Jong-Seok Oh et Seung-Bok Choi. « A ride quality evaluation of a semi-active railway vehicle suspension system with MR damper : Railway field tests ». Proceedings of the Institution of Mechanical Engineers, Part F : Journal of Rail and Rapid Transit 231, n^o 3 (4 août 2016) : 306–16. http://dx.doi.org/10.1177/0954409716629706.

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This work presents experimental assessment of the improvements to the horizontal ride quality of a railway vehicle equipped with a semi-active magneto-rheological (MR) suspension system. The assessment includes the development of a mathematical model and magnetic circuit analysis of the MR damper, the design and manufacture of MR damper, and field test on the railway. After evaluating the field-dependent damping force characteristics, the conventional passive dampers of the operational railway vehicle are replaced with the MR dampers to evaluate horizontal dynamic characteristics that directly indicates the ride quality of the railway vehicle. Various sensors are installed in the vehicle and a skyhook controller with semi-active condition is implemented to produce an appropriate input current for the generation of the desired damping force. Three periods of testing are undertaken on the railway bridge at 120 km/h and the measured data of acceleration level are recoded and presented. It is demonstrated from the measured results that the vibration can be effectively controlled by the proposed semi-active MR suspension system associated with the skyhook controller. Finally, from the vibration control responses the horizontal ride quality of railway vehicle is evaluated and presented in frequency domain.

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OHIRA, Masato, Shuya KUREBAYASHI, Takahisa OHJI et Kenji AMEI. « Finite Element Analysis Verification of the Effect of a New Aluminum Ring Shape for Passive Magnetic Suspension Using AC Electromagnets ». Journal of the Japan Society of Applied Electromagnetics and Mechanics 31, n^o 2 (2023) : 78–83. http://dx.doi.org/10.14243/jsaem.31.78.

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Safaeian, Reza, et Hossein Heydari. « Study effect of the back irons in passive magnetic bearings with alternating radially magnetized rings by using 2D analytical method ». COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 38, n^o 6 (24 octobre 2019) : 1972–85. http://dx.doi.org/10.1108/compel-12-2018-0557.

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Purpose Permanent magnet passive magnetic bearings (PMBs) are used for suspension of rotating shafts in one direction. PMBs with alternating radially magnetized rings having back iron is one of the most optimum configurations among all configurations of PMBs. This paper aims to investigate the effect of the conductivity and permeability of these back irons on the stiffness and damping of the configuration. Design/methodology/approach The stiffness and damping of the configuration will be calculated through a 2D dynamic analytical method and validated by FEM simulations. Findings The results of the paper show how the permeability and conductivity of the back irons can affect stiffness and damping of PMB. Furthermore, the size of the magnets and the air intervals between them are optimized for maximum stiffness and damping. Originality/value The results show that these bearings can have some intrinsic damping without any loss of stiffness, which can be useful for many applications.

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Ładyżyńska-Kozdraś, Edyta, Anna Sibilska-Mroziewicz, Krzysztof Sibilski, Danyil Potoka et Andrzej Żyluk. « Dynamics of Separation of Unmanned Aerial Vehicles from the Magnetic Launcher Cart during Takeoff ». Electronics 12, n^o 13 (29 juin 2023) : 2883. http://dx.doi.org/10.3390/electronics12132883.

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Most aircraft launchers exhibit a rapid acceleration of the launching aircraft, often exceeding ten times the acceleration due to gravity. However, only magnetic launchers offer flexible control over the propulsion force of the launcher cart, enabling precise control over the aircraft’s acceleration and speed during its movement on the launcher. Consequently, extensive research is being conducted on magnetic launchers to ensure the repeatability of launch parameters, protect against aircraft overloads, and ensure operator safety. This article describes the process of modeling and analyzing the dynamical properties of a launch cart of an innovative prototype launcher, which employs a passive magnetic suspension with high-temperature superconductors, developed under the GABRIEL project. The developed mathematical model of the magnetic catapult cart was employed to conduct numerical studies of the longitudinal and lateral movement of the cart, as well as the configuration of the UAV–cart system during UAV takeoff under variable atmospheric conditions. An essential aspect of the research involved experimentally determining the magnetic levitation force generated by the superconductors as a function of the gap. The results obtained demonstrate that the analyzed catapult design enables safe UAV takeoff. External factors and potential vibrations resulting from uneven mass distribution in the UAV–cart system are effectively balanced by the magnetic forces arising from the Meissner effect and the flux pinning phenomenon. The primary advantage of the magnetic levitation catapult, in comparison to commercial catapults, lies in its ability to provide a reduced and consistent acceleration throughout the entire takeoff process.

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Zhang, Yifan, Liang Hu, Rui Su et Xiaodong Ruan. « Design Method of Bearingless Permanent Magnet Slice Motor for Maglev Centrifugal Pump Based on Performance Metric Cluster ». Actuators 10, n^o 7 (5 juillet 2021) : 153. http://dx.doi.org/10.3390/act10070153.

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Different from ordinary AC machines, the design of a bearingless permanent magnet slice motor (BPMSM) considers not only the torque performance, but also the passive and active suspension properties. In addition, BPMSM for a maglev centrifugal pump has unique design characteristics due to the integration of the pump head and sensors. This paper investigates evaluation and design techniques based on a cluster of performance metrics targeting on developing BPMSM for a maglev centrifugal pump. The cluster of performance metrics for BPMSM, including passive stiffness (kz, kz/kx, kz/ky, kα, and kβ) and active factors (ki and cm), is first proposed and an evaluation function fiSi,Li is constructed. Then, practical configurations of BPMSM for a maglev centrifugal pump are summarized. Based on the cluster of performance metrics, the finite-element method (FEM) is used to explore the impact of the rotor magnetization (sinusoidal, diametric, and radial method) on motor properties. Subsequently, the complete design process of BPMSM for a maglev centrifugal pump is introduced and key differences (including three crucial geometric parameters: ratio of rotor height to diameter λ, magnetic gap length δ, and stator tooth width αst) in the design considerations between BPMSM and general bearingless motors are analyzed. Finally, the upgraded performance (kz, kα, kβ, ki, cm, and fiSi,Li increased by about 29%, 38%, 33%, 31%, 21%, and 15%, respectively) of the designed candidate is obtained, which verifies the effectiveness of the proposed design methods.

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T. S., Anilkumar, Yu-Jen Lu et Jyh-Ping Chen. « Optimization of the Preparation of Magnetic Liposomes for the Combined Use of Magnetic Hyperthermia and Photothermia in Dual Magneto-Photothermal Cancer Therapy ». International Journal of Molecular Sciences 21, n^o 15 (22 juillet 2020) : 5187. http://dx.doi.org/10.3390/ijms21155187.

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In this work, we aimed to develop liposomal nanocomposites containing citric-acid-coated iron oxide magnetic nanoparticles (CMNPs) for dual magneto-photothermal cancer therapy induced by alternating magnetic field (AMF) and near-infrared (NIR) lasers. Toward this end, CMNPs were encapsulated in cationic liposomes to form nano-sized magnetic liposomes (MLs) for simultaneous magnetic hyperthermia (MH) in the presence of AMF and photothermia (PT) induced by NIR laser exposure, which amplified the heating efficiency for dual-mode cancer cell killing and tumor therapy. Since the heating capability is directly related to the amount of entrapped CMNPs in MLs, while the liposome size is important to allow internalization by cancer cells, response surface methodology was utilized to optimize the preparation of MLs by simultaneously maximizing the encapsulation efficiency (EE) of CMNPs in MLs and minimizing the size of MLs. The experimental design was performed based on the central composite rotatable design. The accuracy of the model was verified from the validation experiments, providing a simple and effective method for fabricating the best MLs, with an EE of 87% and liposome size of 121 nm. The CMNPs and the optimized MLs were fully characterized from chemical and physical perspectives. In the presence of dual AMF and NIR laser treatment, a suspension of MLs demonstrated amplified heat generation from dual hyperthermia (MH)–photothermia (PT) in comparison with single MH or PT. In vitro cell culture experiments confirmed the efficient cellular uptake of the MLs from confocal laser scanning microscopy due to passive accumulation in human glioblastoma U87 cells originated from the cationic nature of MLs. The inducible thermal effects mediated by MLs after endocytosis also led to enhanced cytotoxicity and cumulative cell death of cancer cells in the presence of AMF–NIR lasers. This functional nanocomposite will be a potential candidate for bimodal MH–PT dual magneto-photothermal cancer therapy.

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Chenchik, D., et J. Jandosov. « Synthesis and Photo-Catalytic Activity of Nanoparticles with Structure "Core/Shell" : Fe3O4@SiO2@TiO2 ». Eurasian Chemico-Technological Journal 19, n^o 2 (30 juin 2017) : 191. http://dx.doi.org/10.18321/ectj651.

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In this work, the nanosized magnetic Fe3O4@SiO2@TiO2 photocatalyst was prepared by sol-gel methods. First the nuclei of magnetite nanoparticles were prepared by co-precipitation of iron (II&III) salts solutions. Secondly, the magnetite nanoparticles were dispersed in ethanol using sonication, and solutions of both ammonia and tetraethoxysilane were added to the suspension under intense stirring, since it was suggested that the introduction of an intermediate passive SiO2 layer between the Fe3O4 and TiO2 phases inhibits the direct electrical contact and hence prevents the photodissolution of the magnetite phase and deterioration of the surface photocatalytic properties. Finally, solution of tetrabutoxytitanium was added dropwise to the mixture of Fe3O4@SiO2 nanoparticles under sonication & intense stirring. The resulting particles were separated using a magnet, washed and dried to constant weight, the yield was 70%. The photocatalytic activity of Fe3O4@ SiO2@TiO2 nanoparticles was investigated by photodegradation of methyl orange in aqueous solution under UV light irradiation. The photodegradation dynamics revealed that even though the oxidation rate decreases over time, about 90% of methyl orange is oxidized during the first 35 min.

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Avison, M. J., S. R. Gullans, T. Ogino, G. Giebisch et R. G. Shulman. « Measurement of Na+-K+ coupling ratio of Na+-K+-ATPase in rabbit proximal tubules ». American Journal of Physiology-Cell Physiology 253, n^o 1 (1 juillet 1987) : C126—C136. http://dx.doi.org/10.1152/ajpcell.1987.253.1.c126.

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A combination of 23Na nuclear magnetic resonance (NMR) spectroscopy and a K+-selective electrode was used to make simultaneous measurements of net Na+ and K+ fluxes across plasma membranes of rabbit renal proximal tubules after an abrupt stimulation of Na+-K+-ATPase. After a step in extracellular K+ concentration ([K+]o) from low to higher concentration (0.1-0.3 mM to 0.5-5.2 mM) at 25 degrees C, net extrusion of Na+ and uptake of K+ were observed. These fluxes were completely inhibited by ouabain (10(-3) M). Because initial rates of K+ uptake in presence or absence of Ba2+ (a known inhibitor of plasma membrane K+ conductance) were indistinguishable, net K+ flux was virtually unidirectional. Because suspension buffers contained neither glucose nor amino acids and the ratio of net Na+ and K+ fluxes (JNa and JK, respectively) was constant over a wide range of transmembrane Na+ gradients and absolute values of the JNa and JK, it is likely that changes in electrogenic or passive net fluxes across plasma membranes were insignificant in the first 30–45 s after the [K+]o step. Thus the ratio of these initial net Na+ and K+ fluxes corresponds closely to the Na+-K+ coupling ratio of the Na+-K+-ATPase. In 12 experiments, the measured Na+-K+-ATPase coupling ratio was 1.54 +/- 0.07 (SE). The coupling ratio was constant over a wide range of intracellular Na+ content, intracellular sodium concentration, [K+]o and transmembrane Na+ gradient. The coupling ratio also remained constant over an eightfold range of Na+-K+-ATPase rates.

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