scholarly journals Gap resonance and higher harmonics driven by focused transient wave groups

2017 ◽  
Vol 812 ◽  
pp. 905-939 ◽  
Author(s):  
W. Zhao ◽  
H. A. Wolgamot ◽  
P. H. Taylor ◽  
R. Eatock Taylor
Keyword(s):  
Incident Wave ◽  
Second Harmonic ◽  
Harmonic Component ◽  
Transient Wave ◽  
Sea State ◽  
Wave Groups ◽  
Wave Basin ◽  
Higher Harmonic ◽  
Harmonic Components ◽  
Quadratic Coupling

The first and higher harmonic components of the resonant fluid response in the gap between two identical fixed rectangular boxes are experimentally investigated in a wave basin. Gap response is excited by transient wave groups (being based on scaled versions of the autocorrelation function of sea-state spectra, representing NewWaves, the average shape of large waves in a sea state). Several different wave groups with different maximum surface elevations, spectral peak frequencies and bandwidths are used, while the bilge shape of the boxes and approach angle of the waves are also varied. Unlike a simple regular wave, it is complicated to separate the harmonic components for a transient wave group due to nonlinear wave–wave and wave–structure interactions. A four-phase combination methodology is used to separate the first four harmonic components, and this also allows higher harmonic components to be isolated with simple digital frequency filtering. Harmonic components up to 14th order in the incident wave amplitude have been extracted. It is shown that for an incident group with appropriate frequency content, the linear gap response may be substantially smaller than the second harmonic component, which is strongly driven via quadratic coupling of the linear terms from the incident wave and occurs in the gap resonant modes. Double frequency excitation may have important practical implications for offshore operations. Fourth and zeroth (long-wave) harmonics in the gap are further driven via quadratic coupling of the second harmonic itself. Linear damping coefficients for the first few modes of the gap resonant response are derived from measured time series using a numerical fit and shown to be higher than those from linear diffraction calculations.

Effect of Higher-Harmonic Deflection Components on the Creep Buckling of Columns

1957 ◽  
Vol 8 (3) ◽  
pp. 215-225 ◽  
Author(s):  
Sharad A. Patel ◽  
Joseph Kempner
Keyword(s):  
Power Function ◽  
Second Harmonic ◽  
Harmonic Component ◽  
Initial Amplitude ◽  
Creep Properties ◽  
Third Harmonic ◽  
Creep Buckling ◽  
Higher Harmonic ◽  
Harmonic Components ◽  
Simple Power Function

SummaryThe influence of higher-harmonic deflection components on the creep-buckling characteristics of an idealised H-section column is investigated. The creep properties of the material of the column are defined by a simple power-function creep law. The results show that higher-harmonic deflection components reduce the column lifetime significantly only when their initial amplitudes, as well as the initial amplitude of the first harmonic component, are very large. Furthermore, it is shown that second-harmonic components have a much smaller effect on the column behaviour than do third-harmonic components.

Development of lateral interactions in the infant visual system

1992 ◽  
Vol 8 (1) ◽  
pp. 3-8 ◽  
Author(s):  
Samuel Sokol ◽  
Vance Zemon ◽  
Anne Moskowitz
Keyword(s):  
Visual System ◽  
Long Range ◽  
Short Range ◽  
Second Harmonic ◽  
Harmonic Component ◽  
Frequency Component ◽  
Human Infants ◽  
Long Range Interactions ◽  
Harmonic Components ◽  
Inhibitory Interactions

AbstractThe development of lateral inhibitory interactions in the infant visual system, as reflected by the visual-evoked potential (VEP), was studied using a radial, asymmetrical windmill-dartboard stimulus. This contrast-reversing stimulus generates VEP responses with a strong fundamental frequency component and an attenuated second harmonic component (relative to that obtained using a symmetrical stimulus). These two harmonic components reflect distinct phenomena, and appear to be the result of short-range (the fundamental) and long-range (attenuated second harmonic) lateral inhibitory interactions elicited by differential luminance-modulation of contiguous spatial regions. We studied the development of the short-and long-range interactions at 100% and 30% contrast in human infants using both VEP amplitude and phase measures. Attenuation of the second harmonic (long-range interactions) was adult-like by 8 weeks of age while the strength of the fundamental (short-range interactions) was adult-like by 20 weeks suggesting a differential development of long-range and short-range interactions. In contrast, corresponding phase data indicated significant immaturities at 20 weeks of age for both the short-and long-range components.

Consideration of Nonsinusoidal/Unbalanced Operating Conditions of a Municipal Electric Network for Calculating the Current Level through the Neutral Conductor

2021 ◽  
Vol 1 (1) ◽  
pp. 35-43
Author(s):  
Mukhammadzhon М. KAMOLOV ◽  
◽  
Sagid A. АBDULKERIMOV ◽  
Khurshed B. NAZIROV ◽  
Shokhin D. DZHURAEV ◽  
...  
Keyword(s):  
Harmonic Component ◽  
Operating Conditions ◽  
Electric Networks ◽  
Electric Network ◽  
Three Phase ◽  
Zero Sequence ◽  
Flow Through ◽  
Higher Harmonic ◽  
Harmonic Components ◽  
Electric Loads

During the operation of 0.4 kV electric networks, asymmetry of currents and voltages is unavoidable. As is known, unbalanced operation of 0.4 kV networks is stemming from nonuniform distribution of loads between the phases. This results in that a fundamental frequency zero-sequence current will flow through the neutral conductor in a four-wire three-phase electric network. On the other hand, during balanced operation of a four-wire electric network containing loads with a nonlinear volt-ampere characteristic, higher harmonic currents multiple to three are summed in the neutral conductor. Therefore, it is of relevance to analyze unbalanced operating conditions of a four-wire electric network containing loads with a nonlinear volt-ampere characteristic. The article presents the characteristics of a municipal load for analyzing unbalanced/nonsinusoidal conditions of its operation. For carrying out full-valued assessment of unbalanced operating conditions of a four-wire electric network, a simulation model of a 0.4 kV network section containing a nonsinusoidal load is developed. It is shown that during unbalanced operation of an electric network containing electric loads with a nonlinear volt-ampere characteristic it is recommended to take into account zero-sequence current higher harmonic components that are not multiple to three. An algorithm for calculating the neutral conductor current harmonic component for determining the cable temperature rating is developed.

NONLINEAR TRANSPORT OF ELECTRONS UNDER A STRONG HIGH FREQUENCY ELECTRIC FIELD IN SEMICONDUCTORS

1992 ◽  
Vol 06 (07) ◽  
pp. 1007-1036 ◽  
Author(s):  
W. Cai ◽  
M. Lax
Keyword(s):  
Electric Field ◽  
High Frequency ◽  
Second Harmonic ◽  
Memory Function ◽  
Harmonic Component ◽  
Nonlinear Transport ◽  
Field Limit ◽  
High Frequency Electric Field ◽  
Dc Electric Field ◽  
Harmonic Components

The nonlinear transport of electrons in semiconductors is studied when a strong high frequency (HF) electric field is applied together with a direct current (dc) electric field. A set of equations is developed, from which the amplitude and phase of each harmonic component of the electron drift velocity and the electron temperature can be computed. In the weak HF field limit our approach reduces to the well-known memory function method. The DC conductivity decreases and definitely becomes negative with increase of the first and second harmonic components of the applied HF field. Comparison is made with experiment.

Electrophysiological correlates of vernier and relative motion mechanisms in human visual cortex

1999 ◽  
Vol 16 (6) ◽  
pp. 1123-1131 ◽  
Author(s):  
ANTHONY M. NORCIA ◽  
WOLFGANG WESEMANN ◽  
RUTH E. MANNY
Keyword(s):  
Relative Motion ◽  
Second Harmonic ◽  
Harmonic Component ◽  
Retinal Eccentricity ◽  
Vernier Acuity ◽  
Full Field ◽  
Spatial Features ◽  
Displacement Threshold ◽  
Harmonic Components ◽  
The One

Vernier onset/offset thresholds were measured both psychophysically and with the steady-state VEP by introducing a series of horizontal breaks in a vertical square-wave luminance grating. Several diagnostic tests indicated that the first harmonic component of the evoked response generated by periodic modulation of offset gratings taps mechanisms that encode the relative position of spatial features. In the first test, a first harmonic component was only found with targets that contained transitions between collinear and noncollinear states. VEP vernier onset/offset thresholds obtained with foveal viewing were in the range of 15–22 arc sec. Control experiments with transitions between symmetrical, noncollinear patterns (relative motion) did not produce first harmonic components, nor did full-field motion of a collinear grating. A second series of experiments showed that VEP thresholds based on the first harmonic component of the vernier onset/offset response had an eccentricity dependence that was very similar to that found in a psychophysical discrimination task that required a left/right position judgment (vernier acuity). Other recordings showed that the first harmonic of the vernier onset/offset VEP was degraded by the introduction of a gap between stimulus elements, as is the displacement threshold. The vernier onset/offset target also produced a second harmonic component that was virtually identical to the one produced by a relative motion stimulus. Displacement thresholds based on these second harmonic components showed a more gradual decline with retinal eccentricity than did the first harmonic component elicited by vernier offsets. The second harmonic of the vernier onset/offset VEP was relatively unaffected by the introduction of gaps between the stimulus elements. The first and second harmonic components of the vernier onset/offset VEP thus tap different mechanisms, both of which support displacement thresholds that are finer than the resolution limits set by the spacing of the photoreceptors (hyperacuity).

scholarly journals Measurement of magnetic noise in magnetoimpedance sensing element

2018 ◽  
Vol 185 ◽  
pp. 02010
Author(s):  
Anatoliy S. Antonov ◽  
Nikita A. Buznikov ◽  
Timur T. Sultan-Zade ◽  
Alexey A. Shkliaev
Keyword(s):  
Second Harmonic ◽  
Signal To Noise Ratio ◽  
Magnetic Noise ◽  
Noise Performance ◽  
Sensing Element ◽  
Field Dependent ◽  
Flux Gate ◽  
Higher Harmonic ◽  
Harmonic Components ◽  
Amorphous Microwires

A method for measurement of magnetic noise in magnetoimpedance sensing element is proposed. Glass-coated Co-based amorphous microwires with a slightly negative magnetostriction were used as the sensing element. The operation principle of the sensing element was based on the nonlinear off-diagonal magnetoimpedance, when field dependent higher harmonic components appeared in voltage in the pick-up coil wound around the microwire. The magnetic noise for the second harmonic in the pick-up coil voltage was studied. The dependences of the magnetic noise and the signal-to-noise ratio in the sensitive element on the current amplitude were analyzed. The noise performance of the second harmonic in the pick-up coil voltage was compared to that for a flux-gate sensing element.

An Experimental Investigation of Wave Steepness and Cylinder Slenderness Effects on Wave Run-Up

2002 ◽  
Author(s):  
Michael Morris-Thomas ◽  
Krish Thiagarajan ◽  
Jo̸rgen Krokstad
Keyword(s):  
Experimental Investigation ◽  
Second Harmonic ◽  
Harmonic Component ◽  
Vertical Surface ◽  
The Body ◽  
Wave Steepness ◽  
Numerical Predictions ◽  
Element Program ◽  
Harmonic Components ◽  
Run Up

This paper details an experimental investigation of wave run-up on a fixed vertical surface piercing circular cylinder. The study focuses on two important parameters, wave steepness and body slenderness, which are shown to influence the wave run-up. The wave steepness, kA, is varied from 0.041–0.284, and the body slenderness parameter, ka, is varied from 0.208–1.386. The zero-, first- and second-harmonic components of the wave run-up are compared with frequency based numerical predictions of the free-surface elevation by a commercially available boundary element program, WAMIT. The comparison illustrates the importance zero- and higher-harmonic contributions to the wave run-up. In particular we show that the linear diffraction prediction of the first-harmonic component is reasonable, however, the trends exhibited by the zero- and second-harmonics are not captured well by perturbation theory. Using a regression analysis, involving a separation of ka and kA dependence, the importance of higher-order wave steepness effects on wave run-up is demonstrated.

Transient Analysis and Modelling of 2nd- and 4th-Order LCLC Filter under Non-Symmetrical Control

1970 ◽  
Vol 111 (5) ◽  
pp. 89-94 ◽  
Author(s):  
B. Dobrucky ◽  
M. Benova ◽  
S. Kascak
Keyword(s):  
Transient Analysis ◽  
Harmonic Distortion ◽  
Harmonic Component ◽  
Switching Frequency ◽  
Sinusoidal Voltage ◽  
Higher Harmonic ◽  
Simulation Results ◽  
Harmonic Components ◽  
Lc Filter

The paper shows how it is possible to obtain the harmonic sinusoidal voltage on the load side at non-harmonic periodical supplying from the converters. It can be used either LCLC resonant filter for frequency of fundamental harmonic component, or LC filter tuned for switching frequency. Both filters have to remove higher harmonic components from the supplying voltage to reach the harmonic distortion roughly 5 %. The paper deals mainly with analysis and modelling of 4th order LCLC filter (of the first type) under non-symmetrical supply and with comparing to the other types of filtering. Simulation results as well as experimental verification confirm good quality of output quantities of the filter. Ill. 19, bibl. 10 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.111.5.364

Amplitude and phase variations of harmonic components in human achromatic and chromatic visual evoked potentials

1996 ◽  
Vol 13 (4) ◽  
pp. 639-653 ◽  
Author(s):  
D. J. McKeefry ◽  
M. H. A. Russell ◽  
I. J. Murray ◽  
J. J. Kulikowski
Keyword(s):  
Evoked Potentials ◽  
Visual Evoked Potentials ◽  
Second Harmonic ◽  
Harmonic Component ◽  
Time Domain Analysis ◽  
Low Contrast ◽  
Response Characteristics ◽  
Wide Range ◽  
Harmonic Components ◽  
Visual Evoked

AbstractOccipital visual evoked potentials (VEPs) were recorded in response to low-contrast, low spatial-frequency chromatic, and achromatic gratings. Fast Fourier Transform (FFT) and time-domain analysis were used to reveal differences in harmonic content and amplitude of chromatic and achromatic response components over a wide range of temporal frequencies. The chromatic ON/OFF VHP is dominated by the fundamental component indicating that onset and offset responses are different. This type of response is typical of neurons with sustained type response characteristics. Conversely, the achromatic onset VEP contains a predominant second harmonic component in addition to the fundamental. This similarity between onset and offset responses suggests that transient mechanisms are responsible for the generation of achromatic components. Frequency analysis of VEPs elicited by phase-reversing stimuli reveals that all of the response energy is concentrated at the second harmonic of the stimulating frequency. The magnitude of the second harmonic component is maximal for achromatic stimuli and undergoes a distinct minimum for isoluminant, chromatic stimuli. This behavior indicates that under the stimulus conditions used, magnocellular neurons with transient characteristics dominate the reversal VEP.

Extreme runup events around a ship-shaped floating production, storage and offloading vessel in transient wave groups

2021 ◽  
Vol 911 ◽  
Author(s):  
L.F. Chen ◽  
P.H. Taylor ◽  
D.Z. Ning ◽  
P.W. Cong ◽  
H. Wolgamot ◽  
...  
Keyword(s):  
Transient Wave ◽  
Wave Groups

Abstract

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