scholarly journals Development of a Tactile Actuator with Non-Contact and Trans-Object Characteristics Using a Time-Varying Magnetic Field

Actuators ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 106
Author(s):  
Hyung-Sik Kim ◽  
Ji-Hun Jo ◽  
Je-Hyeop Lee ◽  
Jin-Ju Jung ◽  
Jin-Su An ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Power Unit ◽  
Tactile Stimulation ◽  
Stimulus Frequency ◽  
Control Unit ◽  
Event Related Potential ◽  
Time Varying ◽  
Output Unit ◽  
Frequency Changes ◽  
The Magnetic Field

A non-contact tactile stimulation system using a time-varying magnetic field was developed. The system comprises a control unit, power unit, output unit, and actuator. The control unit adjusts stimulation parameters, particularly the signal intensity and frequency. The power unit produces high voltages for generating the magnetic field, whereas the output unit transmits the energy generated according to the signal from the control unit to the actuator. A spiral coil actuator generates the magnetic field. To validate the effectiveness of the system, preliminary experiments on 10 male adults without neurological disorders (23.2 ± 3.05 years) were conducted. Magnetic field stimuli were presented to the right palm of the subjects at three different frequencies (10, 30, and 50 Hz), and corresponding electroencephalogram (EEG) signals were measured simultaneously. Event-related potential (ERP) analysis showed that N100 and P300 components were identified in somatosensory areas. Subjective evaluations revealed that feelings such as “tingling,” “trembling,” “tapping,” and “percussing” were induced. Moreover, as the stimulus frequency changes, differences may occur in induced feeling. The system uses a time-varying magnetic field, which not only induces tactile stimulation without contact but also has trans-object characteristics that can present tactile sensations, even when there is an obstacle between an actuator and skin.

Magnetic Field Aligned Potentials as an Acceleration Mechanism at Jupiter

2021 ◽  
Author(s):  
Dave Constable ◽  
Licia Ray ◽  
Sarah Badman ◽  
Chris Arridge ◽  
Chris Lorch ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Temporal Evolution ◽  
Charged Particles ◽  
Uniform Mesh ◽  
Time Varying ◽  
Potential Structure ◽  
Field Aligned Current ◽  
Field Lines ◽  
The Magnetic Field ◽  
Insight Into

<p>Since arriving at Jupiter, Juno has observed instances of field-aligned proton and electron beams, in both the upward and downward current regions. These field-aligned beams are identified by inverted-V structures in plasma data, which indicate the presence of potential structures aligned with the magnetic field. The direction, magnitude and location of these potential structures is important, as it affects the characteristics of any resultant field-aligned current. At high latitudes, Juno has observed potentials of 100’s of kV occurring in both directions. Charged particles that are accelerated into Jupiter’s atmosphere and precipitate can excite aurora; likewise, particles accelerated away from the planet can contribute to the population of the magnetosphere.</p> <p>Using a time-varying 1-D spatial, 2-D velocity space Vlasov code, we examine magnetic field lines which extend from Jupiter into the middle magnetosphere. By applying and varying a potential difference at the ionosphere, we can gain insight into the effect these have on the plasma population, the potential structure, and plasma densities along the field line. Utilising a non-uniform mesh, additional resolution is applied in regions where particle acceleration occurs, allowing the spatial and temporal evolution of the plasma to be examined. Here, we present new results from our model, constrained, and compared with recent Juno observations, and examining both the upward and downward current regions.</p>

scholarly journals EM Site A.C. Magnetic Field Sources, Surveys and Solutions Part IV: Survey Data Analysis

1996 ◽  
Vol 4 (4) ◽  
pp. 20-21
Author(s):  
Curt Dunnam
Keyword(s):  
Magnetic Field ◽  
Data Analysis ◽  
Magnetic Fields ◽  
Survey Data ◽  
Field Survey ◽  
Survey Methods ◽  
Time Varying ◽  
Measured Field ◽  
The Magnetic Field ◽  
Analyze Data

Up to the present waypoint in this series on EM site magnetic fields, we have identified typical sources of time-varying magnetic field intensities, examined salient field characteristics and illustrated correct survey methods. Our goal this month is to analyze data collected at a proposed site and answer the key question of whether or not the candidate site is, as far as magnetic fields go, acceptable for EM use. In the process of analyzing the magnetic field survey data we will define some of the interpretive techniques involved and observe the distinction between localized (a.c. power) and non-localized (geomagnetic) time-varying fields. Finally, we will discuss the implications of EM susceptibility threshold vs. measured field ratios when considering remedial site shielding.

scholarly journals Multiplicity of periodic solutions in bistable equations

2006 ◽  
Vol 462 (2067) ◽  
pp. 1001-1019 ◽  
Author(s):  
Gregory Berkolaiko ◽  
Michael Grinfeld
Keyword(s):  
Magnetic Field ◽  
Periodic Solutions ◽  
Time Varying ◽  
Discontinuous Change ◽  
First Order ◽  
Stable Periodic ◽  
The Mean ◽  
Autonomous Differential Equations ◽  
Ising Magnet ◽  
The Magnetic Field

We study the number of periodic solutions in two first-order non-autonomous differential equations, both of which have been used to describe, among other things, the mean magnetization of an Ising magnet in a time-varying external magnetic field. When the amplitude of the external field is increased, the set of periodic solutions undergoes a bifurcation in both equations. We prove that despite superficial similarities between the equations, the character of the bifurcation can be very different. This results in a different number of coexisting stable periodic solutions in the vicinity of the bifurcation. As a consequence, in one of the models, the Suzuki–Kubo equation, one can effect a discontinuous change in magnetization by adiabatically varying the amplitude of the magnetic field.

Drift wave in the presence of a time varying inhomogeneous electric field

1983 ◽  
Vol 61 (7) ◽  
pp. 1099-1105 ◽  
Author(s):  
K. D. Misra ◽  
R. P. Pandey ◽  
M. S. Tiwari
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Space Plasma ◽  
Time Varying ◽  
Inhomogeneous Electric Field ◽  
Drift Wave ◽  
Plane Normal ◽  
Vlasov Equations ◽  
Drift Instability ◽  
The Magnetic Field

The drift instability has been studied in the presence of an inhomogeneous time varying electric field directed perpendicular to the impressed magnetic field in the presence of a magnetic field, and density and temperature gradients, using nonlinear particle trajectories in the Maxwell–Boltzmann–Vlasov equations. The dispersion relation and growth rate have been evaluated for the drift wave propagating obliquely to the magnetic field in a plane normal to a density gradient. The stabilization/destabilization of the drift wave by the inhomogeneous applied electric field has been discussed. The application of these results has been suggested for space plasma.

New Method of Determiner of the Position of Lightning Stroke Point by Using Dynamic Analysis

2014 ◽  
Vol 675-677 ◽  
pp. 253-256
Author(s):  
Hao Wu ◽  
Yong Huang ◽  
Yu Sheng Quan ◽  
Pu Xin Shi
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Field ◽  
Analytical Method ◽  
Simulation Analysis ◽  
New Method ◽  
Time Varying ◽  
Lightning Stroke ◽  
Exponential Form ◽  
Dynamic Potential ◽  
The Magnetic Field

This paper summarize the existing method that can explain the lightning shield failing and put forward a new method to analyze the development of the leader and the upward leader. By using time-varying electromagnetic field analytical method. Solve the dynamic potential at the streamer zone in the bottom of leader. Give a simulation analysis for the dynamic potential and find the trend grow in exponential form. Deduce the electric field and the magnetic field from the dynamic potential in time-varying electromagnetic field.

Estimating density and magnetic field turbulence in solar flares using radio zebra observations

2020 ◽  
Vol 638 ◽  
pp. A22
Author(s):  
M. Karlický ◽  
L. Yasnov
Keyword(s):  
Magnetic Field ◽  
Solar Flares ◽  
New Method ◽  
Time Varying ◽  
Harmonic Numbers ◽  
Time And Space ◽  
Resonance Model ◽  
Spatially Varying ◽  
Magnetic Field Turbulence ◽  
The Magnetic Field

Context. In solar flares the presence of magnetohydrodynamic turbulence is highly probable. However, information about this turbulence, especially the magnetic field turbulence, is still very limited. Aims. In this paper we present a new method for estimating levels of the density and magnetic field turbulence in time and space during solar flares at positions of radio zebra sources. Methods. First, considering the double-plasma resonance model of zebras, we describe a new method for determining the gyro-harmonic numbers of zebra stripes based on the assumption that the ratio R = Lb/Ln (Ln and Lb are the density and magnetic field scales) is constant in the whole zebra source. Results. Applying both the method proposed in this work and one from a previous paper for comparison, in the 14 February 1999 zebra event we determined the gyro-harmonic numbers of zebra stripes. Then, using the zebra-stripe frequencies with these gyro-harmonic numbers, we estimated the density and magnetic field in the zebra-stripe sources as n = (2.95−4.35) × 1010 cm−3 and B = 17.2−31.9 G, respectively. Subsequently, assuming that the time variation of the zebra-stripe frequencies is caused by the plasma turbulence, we determined the level of the time varying density and magnetic field turbulence in zebra-stripe sources as |Δn/n|t = 0.0112–0.0149 and |ΔB/B|t = 0.0056–0.0074, respectively. The new method also shows deviations in the observed zebra-stripe frequencies from those in the model. We interpret these deviations as being caused by the spatially varying turbulence among zebra-stripe sources; i.e., they depend on their gyro-harmonic numbers. Comparing the observed and model zebra-stripe frequencies at a given time, we estimated the level of this turbulence in the density and magnetic field as |Δn/n|s = 0.0047 and |ΔB/B|s = 0.0024. We found that the turbulence levels depending on time and space in the 14 February 1999 zebra event are different. This indicates some anisotropy of the turbulence, probably caused by the magnetic field structure in the zebra source.

Electromechanical Dynamics of a Four-Link Mechanism Operating in a Magnetic Field

1976 ◽  
Vol 98 (4) ◽  
pp. 1330-1334
Author(s):  
W. D. Smith ◽  
W. S. Reed
Keyword(s):  
Magnetic Field ◽  
Equations Of Motion ◽  
Time Varying ◽  
Current Time ◽  
Magnetic Forces ◽  
Link Mechanism ◽  
Conducting Path ◽  
Flow Through ◽  
Electromechanical Dynamics ◽  
The Magnetic Field

The electromechanical dynamics of a four-link mechanism moving in a magnetic field perpendicular to the plane of motion is considered. As the linkage moves, a voltage is generated around the closed conducting path formed by the mechanism links, causing current to flow through these links. As a result of the magnetic field and this induced current, time varying, distributed magnetic forces act on each link. The equations of motion of the mechanism and the generated current are derived for a torque input on the driving link. These equations are then integrated numerically in an example design.

scholarly journals The effect of compression and expansion of plasma on the generation of synchrotron radiation

1968 ◽  
Vol 35 ◽  
pp. 600-600
Author(s):  
S. J. Gopasyuk ◽  
N. N. Erushev ◽  
Y. I. Neshpor
Keyword(s):  
Magnetic Field ◽  
Synchrotron Radiation ◽  
Field Strength ◽  
Flux Density ◽  
Magnetic Field Strength ◽  
Power Law ◽  
Relativistic Electrons ◽  
Compression And Expansion ◽  
Frequency Changes ◽  
The Magnetic Field

We consider the variation of the synchrotron-flux density of relativistic electrons with the power law spectrum when the region of generation of this emission initially experiences a homogeneous compression and then an expansion. Ionization losses have been taken into account. The velocities of compression and expansion have been taken as constant. It is shown that in the cases of compression or expansion the flux density at a given frequency changes asS(t) ~ S0Kγ(t)where S0 = flux density before the compression, γ = index of the power law spectrum, K(t) = (H(t))/(H0 (t = 0)), and H is the magnetic-field strength. In the case of compression K(t) > 1·0 and in the case of expansion K(t)< 1·0.The results obtained are applied to an explanation of the increasing and decreasing parts of impulsive bursts of the centimeter range. Such a description of the impulsive bursts has allowed us to estimate both the parameters of the radiating region and the parameters of the differential energetic spectrum of relativistic electrons.

scholarly journals The Acoustic Change Complex in Response to Frequency Changes and Its Correlation to Cochlear Implant Speech Outcomes

2021 ◽  
Vol 15 ◽  
Author(s):  
Kelli McGuire ◽  
Gabrielle M. Firestone ◽  
Nanhua Zhang ◽  
Fawen Zhang
Keyword(s):  
Word Recognition ◽  
Cochlear Implant ◽  
Change Detection ◽  
Detection Threshold ◽  
Stimulus Frequency ◽  
Event Related Potential ◽  
Frequency Change ◽  
Eeg Recordings ◽  
Frequency Changes ◽  
Acoustic Change Complex

One of the biggest challenges that face cochlear implant (CI) users is the highly variable hearing outcomes of implantation across patients. Since speech perception requires the detection of various dynamic changes in acoustic features (e.g., frequency, intensity, timing) in speech sounds, it is critical to examine the ability to detect the within-stimulus acoustic changes in CI users. The primary objective of this study was to examine the auditory event-related potential (ERP) evoked by the within-stimulus frequency changes (F-changes), one type of the acoustic change complex (ACC), in adult CI users, and its correlation to speech outcomes. Twenty-one adult CI users (29 individual CI ears) were tested with psychoacoustic frequency change detection tasks, speech tests including the Consonant-Nucleus-Consonant (CNC) word recognition, Arizona Biomedical Sentence Recognition in quiet and noise (AzBio-Q and AzBio-N), and the Digit-in-Noise (DIN) tests, and electroencephalographic (EEG) recordings. The stimuli for the psychoacoustic tests and EEG recordings were pure tones at three different base frequencies (0.25, 1, and 4 kHz) that contained a F-change at the midpoint of the tone. Results showed that the frequency change detection threshold (FCDT), ACC N1′ latency, and P2′ latency did not differ across frequencies (p &gt; 0.05). ACC N1′-P2 amplitude was significantly larger for 0.25 kHz than for other base frequencies (p &lt; 0.05). The mean N1′ latency across three base frequencies was negatively correlated with CNC word recognition (r = −0.40, p &lt; 0.05) and CNC phoneme (r = −0.40, p &lt; 0.05), and positively correlated with mean FCDT (r = 0.46, p &lt; 0.05). The P2′ latency was positively correlated with DIN (r = 0.47, p &lt; 0.05) and mean FCDT (r = 0.47, p &lt; 0.05). There was no statistically significant correlation between N1′-P2′ amplitude and speech outcomes (all ps &gt; 0.05). Results of this study indicated that variability in CI speech outcomes assessed with the CNC, AzBio-Q, and DIN tests can be partially explained (approximately 16–21%) by the variability of cortical sensory encoding of F-changes reflected by the ACC.

scholarly journals Induced Voltage in an Open Wire

2017 ◽  
Vol 72 (7) ◽  
pp. 617-625
Author(s):  
K. Morawetz ◽  
M. Gilbert ◽  
A. Trupp
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Transverse Field ◽  
Open Circuit ◽  
Time Varying ◽  
Induced Voltage ◽  
Symmetry Point ◽  
Field Source ◽  
Symmetry Line ◽  
The Magnetic Field

AbstractA puzzle arising from Faraday’s law has been considered and solved concerning the question which voltage will be induced in an open wire with a time-varying homogeneous magnetic field. In contrast to closed wires where the voltage is determined by the time variance of the magnetic field and the enclosed area, in an open wire we have to integrate the electric field along the wire. It is found that the longitudinal electric field with respect to the wave vector contributes with 1/3 and the transverse field with 2/3 to the induced voltage. In order to find the electric fields the sources of the magnetic fields are necessary to know. The representation of a spatially homogeneous and time-varying magnetic field implies unavoidably a certain symmetry point or symmetry line which depend on the geometry of the source. As a consequence the induced voltage of an open wire is found to be the area covered with respect to this symmetry line or point perpendicular to the magnetic field. This in turn allows to find the symmetry points of a magnetic field source by measuring the voltage of an open wire placed with different angles in the magnetic field. We present exactly solvable models of the Maxwell equations for a symmetry point and for a symmetry line, respectively. The results are applicable to open circuit problems like corrosion and for astrophysical applications.

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