scholarly journals A new class of chimeras in locally coupled oscillators with small-amplitude, high-frequency asynchrony and large-amplitude, low-frequency synchrony

2021 ◽  
Vol 31 (12) ◽  
pp. 123111
Author(s):  
Tasso J. Kaper ◽  
Theodore Vo
Keyword(s):  
High Frequency ◽  
Large Amplitude ◽  
Coupled Oscillators ◽  
Small Amplitude ◽  
Low Frequency ◽  
New Class

Design and Research on the New Combining Vibrating Screen

2011 ◽  
Vol 201-203 ◽  
pp. 504-509 ◽  
Author(s):  
Nian Qin Guo ◽  
Hong Min Lou ◽  
Wei Ping Huang
Keyword(s):  
High Frequency ◽  
Large Amplitude ◽  
Small Amplitude ◽  
Low Frequency ◽  
The Other ◽  
Vibration Exciter ◽  
Vibrating Screen ◽  
Screening Efficiency ◽  
New Type ◽  
Equal Thickness

Basing on the traditional vibrating screen with double amplitudes and different frequency, a new type vibrating screen called combining vibrating screen is developed. It consists of two vibrating screen units. Each unit has an independent vibration exciter, realizing that one screen unit has a parameter of high-frequency with small-amplitude while the other screen unit has a parameter of low-frequency with large-amplitude. The two screen units are installed at different obliquities, so that the equal thickness screening principle can be realized. And comparing with the traditional vibrating screen, its screening efficiency and capacity are greatly improved. This new kind vibrating screen is especially suitable for the dry screening to moist particles.

scholarly journals Performance of a Self-Paced Brain Computer Interface on Data Contaminated with Eye-Movement Artifacts and on Data Recorded in a Subsequent Session

2008 ◽  
Vol 2008 ◽  
pp. 1-13 ◽  
Author(s):  
Mehrdad Fatourechi ◽  
Rabab K. Ward ◽  
Gary E. Birch
Keyword(s):  
Eye Movements ◽  
Eye Movement ◽  
High Frequency ◽  
Large Amplitude ◽  
Low Frequency ◽  
Computer Interface ◽  
Robust Performance ◽  
Contaminated Data ◽  
Online Test ◽  
Movement Artifacts

The performance of a specific self-paced BCI (SBCI) is investigated using two different datasets to determine its suitability for using online: (1) data contaminated with large-amplitude eye movements, and (2) data recorded in a session subsequent to the original sessions used to design the system. No part of the data was rejected in the subsequent session. Therefore, this dataset can be regarded as a “pseudo-online” test set. The SBCI under investigation uses features extracted from three specific neurological phenomena. Each of these neurological phenomena belongs to a different frequency band. Since many prominent artifacts are either of mostly low-frequency (e.g., eye movements) or mostly high-frequency nature (e.g., muscle movements), it is expected that the system shows a fairly robust performance over artifact-contaminated data. Analysis of the data of four participants using epochs contaminated with large-amplitude eye-movement artifacts shows that the system's performance deteriorates only slightly. Furthermore, the system's performance during the session subsequent to the original sessions remained largely the same as in the original sessions for three out of the four participants. This moderate drop in performance can be considered tolerable, since allowing artifact-contaminated data to be used as inputs makes the system available for users at ALL times.

scholarly journals Nonlinear low-frequency gravity waves in a water-filled cylindrical vessel subjected to high-frequency excitations

2013 ◽  
Vol 469 (2153) ◽  
pp. 20120536 ◽  
Author(s):  
Chunyan Zhou ◽  
Dajun Wang ◽  
Song Shen ◽  
Jing Tang Xing
Keyword(s):  
Gravity Waves ◽  
High Frequency ◽  
Water Waves ◽  
Large Amplitude ◽  
Low Frequency ◽  
Approximation Model ◽  
Fluid Structure Interactions ◽  
Governing Equations ◽  
Low Frequencies ◽  
Nonlinear Fluid

In the experiments of a water storage cylindrical shell, excited by a horizontal external force of sufficient large amplitude and high frequency, it has been observed that gravity water waves of low frequencies may be generated. This paper intends to investigate this phenomenon in order to reveal its mechanism. Considering nonlinear fluid–structure interactions, we derive the governing equations and the numerical equations describing the dynamics of the system, using a variational principle. Following the developed generalized equations, a four-mode approximation model is proposed with which an experimental case example is studied. Numerical calculation and spectrum analysis demonstrate that an external excitation with sufficient large amplitude and high frequency can produce gravity water waves with lower frequencies. The excitation magnitude and frequencies required for onset of the gravity waves are found based on the model. Transitions between different gravity waves are also revealed through the numerical analysis. The findings developed by this method are validated by available experimental observations.

Comparing the Effects of Ultrasonic System of the EDM Process on Machining Cemented Carbide

2019 ◽  
Vol 950 ◽  
pp. 195-199
Author(s):  
Boonsong Chongkolnee ◽  
Chaiya Praneetpongrung
Keyword(s):  
Ultrasonic Vibration ◽  
High Frequency ◽  
Small Amplitude ◽  
Vibration Amplitude ◽  
Low Frequency ◽  
Cemented Carbide ◽  
Tool Electrode ◽  
Vibration Technique ◽  
Machining Properties ◽  
Large Vibration Amplitude

This research aim to improve the machining properties of the EDM for cemented carbide. The new methods were designed and proposed to use the ultrasonic vibration technique. Two types of USEDM systems were produced. One had a low frequency of 29 kHz with a large vibration amplitude, while the other had a high frequency of 59 kHz with a small amplitude. The Cu-W tool electrode was synchronized with the devised vibration system, and several discharge generation conditions were carried out on the cemented carbide material. The results showed that the highest machining efficiencies were obtained from the ultrasonic low frequency of 29 kHz with a large vibration amplitude. The MRR, TWR and surface roughness of the ultrasonic low frequency with the large vibration amplitude were better than the high frequency system with the small amplitude system. It was clarified that the ultrasonic vibration with the large amplitude could assist the material removal behavior of the discharge.

Theory of stimulated scattering of large-amplitude waves

1999 ◽  
Vol 61 (1) ◽  
pp. 129-134 ◽  
Author(s):  
L. STENFLO
Keyword(s):  
Dispersion Relation ◽  
High Frequency ◽  
Large Amplitude ◽  
Pump Wave ◽  
Low Frequency ◽  
Nonlinear Dispersion ◽  
Stimulated Scattering ◽  
Nonlinear Dispersion Relation

A nonlinear dispersion relation that governs the interaction between a high-frequency pump wave and the low-frequency modes in a plasma is derived. Previous results are generalized and discussed.

scholarly journals Compressive high-frequency waves riding on an Alfvén/ion-cyclotron wave in a multi-fluid plasma

2011 ◽  
Vol 77 (5) ◽  
pp. 693-707 ◽  
Author(s):  
DANIEL VERSCHAREN ◽  
ECKART MARSCH
Keyword(s):  
Acoustic Waves ◽  
High Frequency ◽  
Large Amplitude ◽  
Wave Equations ◽  
Low Frequency ◽  
Plasma Waves ◽  
Alpha Particles ◽  
Alfven Wave ◽  
Resonant Wave ◽  
High Frequency Waves

AbstractIn this paper, we study the weakly-compressive high-frequency plasma waves which are superposed on a large-amplitude Alfvén wave in a multi-fluid plasma consisting of protons, electrons, and alpha particles. For these waves, the plasma environment is inhomogenous due to the presence of the low-frequency Alfvén wave with a large amplitude, a situation that may apply to space plasmas such as the solar corona and solar wind. The dispersion relation of the plasma waves is determined from a linear stability analysis using a new eigenvalue method that is employed to solve the set of differential wave equations which describe the propagation of plasma waves along the direction of the constant component of the Alfvén wave magnetic field. This approach also allows one to consider weak compressive effects. In the presence of the background Alfvén wave, the dispersion branches obtained differ significantly from the situation of a uniform plasma. Due to compressibility, acoustic waves are excited and couplings between various modes occur, and even an instability of the compressive mode. In a kinetic treatment, these plasma waves would be natural candidates for Landau-resonant wave–particle interactions, and may thus via their damping lead to particle heating.

Energy Transfer from High-Frequency to Low-Frequency Modes in Structures

1995 ◽  
Vol 117 (B) ◽  
pp. 186-195 ◽  
Author(s):  
A. H. Nayfeh ◽  
D. T. Mook
Keyword(s):  
Energy Transfer ◽  
High Frequency ◽  
Large Amplitude ◽  
Low Frequency ◽  
Internal Resonances ◽  
Parametric Resonances ◽  
High Frequency Excitation ◽  
Frequency Excitation ◽  
Low Amplitude

A perspective of the mechanisms by which energy is transferred from high- to low-frequency modes is presented. The focus is on some recent experiments that reveal how a low-amplitude high-frequency excitation can produce a large-amplitude low-frequency response. Such a phenomenon is potentially harmful, if not catastrophic. Specifically, these experiments clarify the role of internal resonances, combination external and parametric resonances, and the interactions among modes of widely spaced frequencies.

Energy Transfer from High-Frequency to Low-Frequency Modes in Structures

1995 ◽  
Vol 117 (B) ◽  
pp. 186-195 ◽  
Author(s):  
A. H. Nayfeh ◽  
D. T. Mook
Keyword(s):  
Energy Transfer ◽  
High Frequency ◽  
Large Amplitude ◽  
Low Frequency ◽  
Internal Resonances ◽  
Parametric Resonances ◽  
High Frequency Excitation ◽  
Frequency Excitation ◽  
Low Amplitude

A perspective of the mechanisms by which energy is transferred from high- to low-frequency modes is presented. The focus is on some recent experiments that reveal how a low-amplitude high-frequency excitation can produce a large-amplitude low-frequency response. Such a phenomenon is potentially harmful, if not catastrophic. Specifically, these experiments clarify the role of internal resonances, combination external and parametric resonances, and the interactions among modes of widely spaced frequencies.

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