Comparison of Linear and Nonlinear Electromagnetic Coupling Models for a Linear Oscillator

2011 ◽  
Author(s):  
Benjamin A. M. Owens ◽  
Brian P. Mann
Keyword(s):  
Peak Power ◽  
Nonlinear Models ◽  
Electromagnetic Coupling ◽  
Analytical Models ◽  
Linear Oscillator ◽  
System Response ◽  
Excitation Threshold ◽  
Current Response ◽  
And Behavior ◽  
Low Amplitude

This paper examines the modeling and behavior of two forms of electromagnetic coupling with a linear oscillator. With coupling as either a linear or a nonlinear term dependent on position, analytical results were derived and numerical simulations performed for the mechanical and electrical system response. Analytical models were found to correlate well with their respective simulations. Linear coupling showed wider power bandwidth at certain excitation levels and higher theoretical power output than nonlinear beyond an excitation threshold. Nonlinear models showed increasingly complex harmonic current response at high excitation amplitudes and increased peak power at low amplitude excitation levels for certain offset coil positions.

Damped Transition of a Strongly Nonlinear System of Coupled Oscillators Into a State of Continuous Resonance Scattering

2011 ◽  
Author(s):  
David Andersen ◽  
Xingyuan Wang ◽  
Yuli Starosvetsky ◽  
Kevin Remick ◽  
Alexander Vakakis ◽  
...  
Keyword(s):  
Equations Of Motion ◽  
Resonance Scattering ◽  
Linear Oscillator ◽  
System Response ◽  
Analytical Treatment ◽  
Strongly Nonlinear ◽  
Damped System ◽  
Initial Excitation ◽  
Strongly Nonlinear System ◽  
Energy Plane

We examine analytically and experimentally a new phenomenon of ‘continuous resonance scattering’ in an impulsively excited, two-mass oscillating system. This system consists of a grounded damped linear oscillator with a light, strongly nonlinear attachment. Previous numerical simulations revealed that for certain levels of initial excitation, the system engages in a special type of response that appears to track a solution branch formed by the so-called ‘impulsive orbits’ of this system. By this term we denote the periodic (under conditions of resonance) or quasi-periodic (under conditions of non-resonance) responses of the system when a single impulse is applied to the linear oscillator with the system being initially at rest. By varying the magnitude of the impulse we obtain a manifold of impulsive orbits in the frequency-energy plane. It appears that the considered damped system is capable of entering into a state of continuous resonance scattering, whereby it tracks the impulsive orbit manifold with decreasing energy. Through analytical treatment of the equations of motion, a direct relationship is established between the frequency of the nonlinear attachment and the amplitude of the linear oscillator response, and a prediction of the system response during continuous scattering resonance is provided. Experimental results confirm the analytical predictions.

Human auditory system response to modulated electromagnetic energy

1962 ◽  
Vol 17 (4) ◽  
pp. 689-692 ◽  
Author(s):  
Allan H. Frey
Keyword(s):  
Power Density ◽  
Peak Power ◽  
Acoustic Noise ◽  
Average Power ◽  
Critical Factor ◽  
Electromagnetic Energy ◽  
Acoustic Energy ◽  
System Response ◽  
Peak Power Density ◽  
Energy Sensor

The intent of this paper is to bring a new phenomenon to the attention of physiologists. Using extremely low average power densities of electromagnetic energy, the perception of sounds was induced in normal and deaf humans. The effect was induced several hundred feet from the antenna the instant the transmitter was turned on, and is a function of carrier frequency and modulation. Attempts were made to match the sounds induced by electromagnetic energy and acoustic energy. The closest match occurred when the acoustic amplifier was driven by the rf transmitter's modulator. Peak power density is a critical factor and, with acoustic noise of approximately 80 db, a peak power density of approximately 275 mw/ cm2 is needed to induce the perception at carrier frequencies of 425 mc and 1,310 mc. The average power density can be at least as low as 400 μw/cm2. The evidence for the various possible sites of the electromagnetic energy sensor are discussed and locations peripheral to the cochlea are ruled out.

scholarly journals Generation of Subpicosecond Pulse Trains in Fiber Cascades Comprising a Cylindrical Waveguide with Propagating Refractive Index Wave

Photonics ◽  
2021 ◽  
Vol 8 (11) ◽  
pp. 484
Author(s):  
Aleksei Abramov ◽  
Igor Zolotovskii ◽  
Vladimir Kamynin ◽  
Andrei Domanov ◽  
Aleksandr Alekseev ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Fiber ◽  
Peak Power ◽  
Continuous Wave ◽  
Optical Gain ◽  
High Repetition Rate ◽  
Cylindrical Waveguide ◽  
Picosecond Pulses ◽  
Pulse Trains ◽  
Low Amplitude

A cylindrical waveguide structure with the running refractive index wave has been recently demonstrated as a means for the generation of high-repetition-rate pulse trains. The operation mechanism involves a proper combination of the frequency modulation and modulation instability simultaneously experienced by the input continuous wave (CW) signal as it propagates through the cylinder waveguide. Here, we explore the same idea but employ the cylindrical waveguide only as a part of the cascaded optical fiber configuration now comprising both passive and active optical fiber segments. The new system design enables the improved control of the pulse train formation process in the cascaded system elements, relaxes strong requirements for the CW signal power, and provides an additional optical gain for the advanced pulse peak power scaling. In particular, using a low-amplitude, weakly modulated, continuous wave as an input signal we explore and optimize the nonlinear mechanisms underlying its cascaded transformation into the train of kilowatt peak power picosecond pulses.

Transient electromagnetic field computations for polygonal loops on layered earths

Geophysics ◽  
1987 ◽  
Vol 52 (6) ◽  
pp. 785-793 ◽  
Author(s):  
A. P. Raiche
Keyword(s):  
Digital Filters ◽  
Computation Time ◽  
Hankel Transform ◽  
Electromagnetic Response ◽  
System Response ◽  
Current Response ◽  
Loop Area ◽  
Transient Electromagnetic ◽  
The Time Domain ◽  
Dipole Response

The transient electromagnetic response (vertical and horizontal components of dB/dt) of a large polygonal transmitting loop on a layered earth is calculated using a nested interpolation scheme based on the dipole‐dipole response function. The frequency‐domain field of a vertical magnetic dipole is inverse Laplace transformed into the time domain, for selected values of the Hankel transform variable, using the Gaver‐Stehfest method. After interpolation, the result is inverse Hankel transformed (for selected values of distance) using digital filters. Interpolating over distance allows integration of the dipole response over the area of one or more transmitting loops. An interpolation over time gives the step‐current response, which in turn is convolved with the transmitter‐receiver characteristics to yield the system response. This method allows robust calculation of several transmitting loops (with different signal parameters) and several receiver positions in little more time than that required for one loop with one receiver. The computation time for the single transmitter‐receiver response can be decreased by analytical integration of the Bessel function over the transmitter loop area before performing the inverse Hankel transform. Since this procedure precludes the use of standard digital filters for the inverse Hankel transform, it is not efficient for multireceiver computations.

The Motor Output and Behavior Produced by Rhythmogenic Sacrocaudal Networks in Spinal Cords of Neonatal Rats

2001 ◽  
Vol 85 (5) ◽  
pp. 2100-2110 ◽  
Author(s):  
I. Delvolvé ◽  
H. Gabbay ◽  
A. Lev-Tov
Keyword(s):  
High Amplitude ◽  
Motor Output ◽  
Neonatal Rats ◽  
Motor Behaviors ◽  
Afferent Projections ◽  
Unilateral Stimulation ◽  
Afferent Activation ◽  
And Behavior ◽  
Low Amplitude ◽  
Stimulation Of

The characteristics of the rhythmic motor output and behavior produced by intrinsic sacrocaudal networks were studied in isolated tail-spinal cord preparations of neonatal rats. An alternating left-right rhythm could be induced in the sacral cord by stimulus trains applied to sacrocaudal afferents at various intensities. Strengthening the stimulation intensity enhanced the rhythmic efferent firing and accelerated the rhythm by ≤30%. High stimulation intensities induced tonic excitation or inhibition and thereby perturbed the rhythm. Increasing the stimulation frequency from 1 to 10 Hz decreased the cycle time of the rhythm by 36%. The rhythm was blocked during prolonged afferent stimulation but could be restored by stimulation of contralateral afferents. Sacrocaudal afferent activation produced ventroflexion accompanied by either low- or high-amplitude rhythmic abduction of the tail. The low-amplitude abductions were produced by alternating flexor bursts during long stimulus trains. The activity of abductors and extensors was substantially reduced during these trains, their recruitment lagged after that of the flexors, and their activity bursts were much shorter. It is suggested that tail extensor/abductor motoneurons were suppressed during the stimulus train by inhibitory afferent projections. The high-amplitude abductions appeared after cessation of stimulus trains. Alternating left-right activation of the tail muscles, and coactivation of the principal muscles on each side of the tail were observed during these abductions. It is suggested that flexors and extensors assist the abductors to produce the high-amplitude abductions. This suggestion is supported by the finding that tail abduction could be produced by direct unilateral stimulation of any of the principal tail muscles. The relevance of the findings described in the preceding text to the use of regional sacral circuits in generation of stereotypic motor behaviors and to future studies of rhythmogenic sacrocaudal networks is discussed.

scholarly journals Design of Chatter-Resistant Damped Boring Bars Using a Receptance Coupling Approach

2020 ◽  
Vol 4 (2) ◽  
pp. 53 ◽  
Author(s):  
Ajay Yadav ◽  
Devangkumar Talaviya ◽  
Ankit Bansal ◽  
Mohit Law
Keyword(s):  
Stability Limit ◽  
Analytical Models ◽  
Classical Solutions ◽  
System Response ◽  
Chatter Vibration ◽  
Boring Bar ◽  
Damped System ◽  
Receptance Coupling ◽  
Coupling Approach ◽  
Stiffness And Damping

Deep hole boring using slender bars that have tuned mass dampers integrated within them make the boring process chatter vibration resistant. Dampers are usually designed using classical analytical solutions that presume the (un)damped boring bar which can be approximated by a single degree of freedom system, and the damper is placed at the free end. Since the free end is also the cutting end, analytical models may result in infeasible design solutions. To place optimally tuned dampers within boring bars, but away from the free end, this paper presents a receptance coupling approach in which the substructural receptances of the boring bar modelled as a cantilevered Euler–Bernoulli beam are combined with the substructural receptances of a damper modelled as a rigid mass integrated anywhere within the bar. The assembled and damped system response thus obtained is used to predict the chatter-free machining stability limit. Maximization of this limit is treated as the objective function to find the optimal mass, stiffness and damping of the absorber. Proposed solutions are first verified against other classical solutions for assumed placement of the absorber at the free end. Verified models then guide prototyping of a boring bar integrated with a damper placed away from its free end. Experiments demonstrate a ~100-fold improvement in chatter vibration free machining capability. The generalized methods presented herein can be easily extended to design and develop other damped and chatter-resistant tooling systems.

Predicting Macroscopic Dynamics in Large Distributed Systems: Part I

2011 ◽  
Author(s):  
K. L. Mills ◽  
J. J. Filliben ◽  
D.-Y. Cho ◽  
E. J. Schwartz
Keyword(s):  
Distributed Systems ◽  
Congestion Control ◽  
Analytical Models ◽  
Multidimensional Data ◽  
System Response ◽  
Small Scale ◽  
The Internet ◽  
Essential Information ◽  
Data Flows ◽  
Test Beds

Society increasingly depends on large distributed systems, such as the Internet and Web-based service-oriented architectures deployed over the Internet. Such systems constantly evolve as new software components are injected to provide increased functionality, better performance and enhanced security. Unfortunately, designers lack effective methods to predict how new components might influence macroscopic behavior. Lacking effective methods, designers rely on engineering techniques, such as: analysis of critical algorithms at small scale and under limiting assumptions; factor-at-a-time simulations conducted at modest scale; and empirical measurements in small test beds. Such engineering techniques enable designers to characterize selected properties of new components but reveal little about likely dynamics at global scale. In this paper, we outline an approach that can be used to predict macroscopic dynamics when new components are deployed in a large distributed system. Our approach combines two main methods: scale reduction and multidimensional data analysis techniques. Combining these methods, we can search a wide parameter space to identify factors likely to drive global system response and we can predict the resulting macroscopic dynamics of key system behaviors. We demonstrate our approach in the context of the Internet, where researchers, motivated by a desire to increase user performance, have proposed new algorithms to replace the standard congestion control mechanism. Previously, the proposed algorithms were studied in three ways: using analytical models of single data flows, using empirical measurements in test beds where a few data flows compete for bandwidth, and using simulations at modest scale with a few sequentially varied parameters. In contrast, by applying our approach, we simulated configurations covering four-tier network topologies, spanning continental and global distances, comprising routers operating at state-of-the-art speeds and transporting more than 105 simultaneous data flows with varying traffic patterns and temporary spatiotemporal congestion. Our findings identify the main factors influencing macroscopic dynamics of Internet congestion control, and define the specific combination of factors that must hold for users to realize improved performance. We also uncover potential for one proposed algorithm to cause widespread performance degradation. Previous engineering studies of the proposed congestion control algorithms were unable to reveal such essential information.

Analytical Models for Electromagnetic Coupling of an Open Metallic Shield Containing a Loaded Wire

2017 ◽  
Vol 59 (5) ◽  
pp. 1634-1637 ◽  
Author(s):  
Amelie Rabat ◽  
Pierre Bonnet ◽  
Khalil El Khamlichi Drissi ◽  
Sebastien Girard
Keyword(s):  
Electromagnetic Coupling ◽  
Analytical Models
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