Non-linear dynamics of the Villari effect in the presence of a non-homogeneous magnetic field

2018 ◽  
Vol 233 (4) ◽  
pp. 431-440
Author(s):  
Andrzej Rysak ◽  
Magdalena Gregorczyk
Keyword(s):  
Magnetic Field ◽  
Time Series ◽  
Hysteresis Loops ◽  
Bias Field ◽  
Homogeneous Magnetic Field ◽  
Operating Conditions ◽  
Bias Magnetic Field ◽  
Linear Dynamics ◽  
Non Linear ◽  
Magnetostrictive Devices

Investigations of systems with an active magnetostrictive element generally assume the presence of an external homogeneous bias magnetic field. This article, however, presents the results of a study investigating a bimorph magnetostrictive-aluminium beam vibrating in a non-homogeneous bias field. By comparing results obtained under different operating conditions of the system, the combined effect of the non-linear beam stress and the non-homogeneous external magnetic field on the dynamics of the Villari phenomenon is determined. The preliminary results prove that the application of non-linear magnetic fields to the magnetostrictive devices ensures the extension of energy harvesting bandwidth of these devices and can be used to improve their control possibilities. A study of time series and hysteresis loops provides more detailed information about the non-linear magnetization and dynamics of the system.

scholarly journals Alternating current magnetic susceptibility of a ferronematic

2017 ◽  
Vol 8 ◽  
pp. 2515-2520 ◽  
Author(s):  
Natália Tomašovičová ◽  
Jozef Kováč ◽  
Veronika Gdovinová ◽  
Nándor Éber ◽  
Tibor Tóth-Katona ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
Soft Matter ◽  
Experimental Studies ◽  
Bias Field ◽  
Information Storage ◽  
Isotropic Phase ◽  
Ac Magnetic Susceptibility ◽  
Bias Magnetic Field ◽  
Dc Bias

We report on experimental studies focusing on the dynamic ac magnetic susceptibility of a ferronematic. It has been shown recently, that in the isotropic phase of a ferronematic, a weak dc bias magnetic field of a few oersteds increases the ac magnetic susceptibility. This increment vanishes irreversibly if the substance is cooled down to the nematic phase, but can be reinduced by applying the dc bias field again in the isotropic phase [Tomašovičová, N. et al. Soft Matter 2016, 12, 5780–5786]. The effect has no analogue in the neat host liquid crystal. Here, we demonstrate that by doubling the concentration of the magnetic nanoparticles, the range of the dc bias magnetic field to which the ferronematic is sensitive without saturation can be increased by about two orders of magnitude. This finding paves a way to application possibilities, such as low magnetic field sensors, or basic logical elements for information storage.

Displacement model of the giant magnetostrictive actuator with strong bias magnetic field at low frequency

2016 ◽  
Vol 230 (19) ◽  
pp. 3568-3574
Author(s):  
Xue Guangming ◽  
Zhang Peilin ◽  
He Zhongbo ◽  
Li Dongwei ◽  
Yang Zhaoshu ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Low Frequency ◽  
Experimental System ◽  
Bias Field ◽  
Bias Magnetic Field ◽  
Exciting Frequency ◽  
Magnetostrictive Actuator ◽  
Mass Spring ◽  
Displacement Model ◽  
The Relationship

A giant magnetostrictive actuator is designed with strong bias magnetic field. The influence of the strong bias field is introduced, and the corresponding exciting input signal is selected. Magnetic reluctance estimation, approximate linearity between the strain and magnetic field, and a mass–spring–damper system assumption are employed to analyze the actuator’s displacement with low-frequency signal input. An experimental system is designed, and properties of the proposed actuator are tested. With the help of square wave test, appropriate direction of exciting signal for the magnetostrictive actuator is determined. With the help of sinusoidal wave test, the established model is validated and the relationship between the maximum value of the displacement and of the current is analyzed. With exciting frequency lower than 200 Hz, the errors between the calculating and testing results are within 1.0 m, which validates the model.

scholarly journals On the progress of the 2015–2016 El Niño event

2016 ◽  
Vol 16 (4) ◽  
pp. 2007-2011 ◽  
Author(s):  
Costas A. Varotsos ◽  
Chris G. Tzanis ◽  
Nicholas V. Sarlis
Keyword(s):  
Time Series ◽  
El Niño ◽  
Southern Oscillation Index ◽  
El Nino ◽  
Southern Oscillation ◽  
Linear Dynamics ◽  
El Niño Event ◽  
Non Linear ◽  
El Niño Events ◽  
Index Time Series

Abstract. It has been recently reported that the current 2015–2016 El Niño could become "one of the strongest on record". To further explore this claim, we performed the new analysis described in detail in Varotsos et al. (2015) that allows the detection of precursory signals of the strong El Niño events by using a recently developed non-linear dynamics tool. In this context, the analysis of the Southern Oscillation Index time series for the period 1876–2015 shows that the running 2015–2016 El Niño would be rather a "moderate to strong" or even a "strong" event and not “one of the strongest on record", as that of 1997–1998.

scholarly journals Magnetoelectric effect in a Terfenol-D and electret capacitor system

2018 ◽  
Vol 238 ◽  
pp. 01004
Author(s):  
Tian-Xiang Gao ◽  
Yan-Wei Zhou ◽  
Su-Su Wang ◽  
Yun Zhou
Keyword(s):  
Magnetic Field ◽  
Magnetoelectric Effect ◽  
Hysteresis Loops ◽  
Dynamic Measurement ◽  
Test Period ◽  
Bias Magnetic Field ◽  
Magnetoelectric Sensors ◽  
Potential Applications ◽  
Dc Bias

A capacitor system based on a Terfenol-D rod and an electret film has been proposed. We used the traditional dynamic measurement to investigate the magnetoelectric effect of the system at the frequency of 50 kHz. The results show that the ME coefficient of the system is significantly affected by the DC bias magnetic field. The maximum tunability of the magnetoelectric effect based on the DC bias magnetic field is more than 10%. The induced AC voltage of effective values increases almost lineally with increasing AC signal magnetic field. The detected magnetoelectric effect of the system exhibits hysteresis, and the magnetoelectric hysteresis loops are almost unchanged with the test period. These findings provide a type of capacitor for potential applications in magnetic detections and magnetoelectric sensors.

Impulse acoustics based ejection of ferrofluid grains from a ferrofluid: the blueprint of a concept for a nozzle-free inkjet printer

2000 ◽  
Vol 627 ◽  
Author(s):  
Felicia S. Manciu ◽  
Marian Manciu ◽  
Surajit Sen
Keyword(s):  
Magnetic Field ◽  
Numerical Simulations ◽  
Homogeneous Magnetic Field ◽  
Magnetic Dipoles ◽  
Non Linear ◽  
Dynamical Simulations ◽  
Inkjet Printers ◽  
Inkjet Printer

ABSTRACTWe present numerical simulations to demonstrate that it may be possible to eject ferrofluid grains from a ferrofluid using non-linear acoustic impulses. The study considers a container with some dilute ferrofluid that is placed in a strong, vertical, homogeneous magnetic field. The field induces the formation of magnetic dipoles into vertical chains that approximately span the region between the base and the surface of the container. We use particle dynamical simulations to show that an impulse generated at the base of any chain, will typically travel as a weakly dispersive bundle of energy. When the impulse magnitudes are appropriate (typically ∼60 m/s or more) the ferrofluid grain nearest to the surface of the liquid may be ejected by the impulse. Since all ferrofluid grains possess a coating of the liquid host, the ejected grain can be used as an ink-drop, with typical diameter of 15 or so nanometers. The velocities of the ejecting grains can be controlled and hence the method, if experimentally feasible, may have wide ranging applications. One of these applications is likely to be in designing special-purpose nozzle-free inkjet printers of unprecedented resolution.

scholarly journals Technical note: On the progress of the 2015–2016 El Niño event

2015 ◽  
Vol 15 (24) ◽  
pp. 35787-35797 ◽  
Author(s):  
C. A. Varotsos ◽  
C. G. Tzanis ◽  
N. V. Sarlis
Keyword(s):  
Time Series ◽  
El Niño ◽  
Southern Oscillation Index ◽  
El Nino ◽  
Southern Oscillation ◽  
Technical Note ◽  
Linear Dynamics ◽  
El Niño Event ◽  
Non Linear ◽  
Index Time Series

Abstract. It has been recently reported that the current 2015–2016 El Niño could become "one of the strongest on record". To further explore this claim, we performed the new analysis described in detail in Varotsos et al. (2015) that allows the detection of precursory signals of the strong El Niño events by using a recently developed non-linear dynamics tool. In this context, the analysis of the Southern Oscillation Index time series for the period 1876–2015 shows that the running 2015–2016 El Niño would be rather a "moderate to strong" or even a "strong" event and not "one of the strongest on record", as that of 1997–1998.

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