Experimental Verification of an Approximate Admittance Equation for Center-Fed Dipoles Arranged Parallel Beside Each Other and Estimation of Its Effective Frequency Range

2021 ◽  
Author(s):  
Kyoichi Iigusa ◽  
Hirokazu Sawada ◽  
Takeshi Matsumura ◽  
Fumihide Kojima ◽  
Hiroshi Harada
Keyword(s):  
Experimental Verification ◽  
Frequency Range ◽  
Effective Frequency

The effective frequency range of an active suspended handle based on the saturation effects of a piezo stack actuator

2016 ◽  
Vol 23 (5) ◽  
pp. 752-769 ◽  
Author(s):  
Ahmad Zhafran Ahmad Mazlan ◽  
Zaidi Mohd Ripin
Keyword(s):  
Excitation Frequency ◽  
Saturation Effect ◽  
Feedback Gain ◽  
Operating Speed ◽  
Frequency Range ◽  
Effective Frequency ◽  
Novel Approach ◽  
Saturation Effects ◽  
Force Displacement ◽  
Proportional Feedback

This paper presents a novel approach to the design of an active suspended handle by identifying the effective frequency range, based on the saturation effects of the piezo stack actuator, in terms of the force-displacement-voltage relationship as a function of the excitation frequency. The effective range allows for proper matching between the operating speed of the machine and the suspended handle. A model of the active suspended handle was developed, which took into account the non-linear saturation effect of the piezo stack actuator. A proportional-integral-derivative controller generated the counter voltage for the piezo stack actuator, using a proportional feedback gain (P) step up method, in order to attenuate the vibration transmitted to the handle. By including the saturation effect, the Pearson’s correlation coefficient ( R2) of the model improved to 0.97, within the frequency range of 50 ∼ 500 Hz. Using this approach, we identified that the effective frequency range of isolation with transmissibility less than unity is between 250 ∼ 450 Hz. The active suspended handle was attached to a die grinder with a nominal operating speed of 25000 rpm and the vibration transmitted from the die grinder to the handle was reduced by 91%.

Traveling-wave control of the bending wave in a beam for high quality sound radiation

2021 ◽  
Vol 263 (6) ◽  
pp. 925-928
Author(s):  
Ki-Ho Lee ◽  
Jeong-Guon Ih ◽  
Donghyun Jung
Keyword(s):  
Traveling Wave ◽  
Control Method ◽  
Wave Form ◽  
Frequency Range ◽  
Effective Frequency ◽  
Reflected Waves ◽  
Radiated Sound ◽  
Sound Spectrum ◽  
Bending Wave ◽  
Wave Control

The bending wave generated by the actuator exciting a panel can be controlled to be in the traveling wave form void the structural resonances, which deteriorates the radiated sound if the panel is used as a speaker. Although such traveling-wave control method (TCM) yields a wider effective frequency range than the modal control method, the requirement of using many actuators is the practical problem yet. If a beam is employed instead of a plate as a panel speaker, the number of actuators can be reduced despite a smaller radiating surface than a plate. This study adopts three actuators for the beam control using TCM. An actuator excites the beam in the middle position, and the two actuators near the two edges are used to suppress the reflected waves from the boundaries. The control result shows that the driving-point mobility of the primary actuator is converted into that of an infinite beam, which means that the boundaries are changed into anechoic ones and the structural resonances are eliminated. Accordingly, the beam radiates a smooth sound spectrum without sharp peaks and troughs related to the resonant responses. Effects of material and dimension in determining the effective frequency range are also explored.

Experimental investigation on hydrodynamic performance of a dual pontoon–power take-off type wave energy converter integrated with floating breakwaters

2018 ◽  
Vol 233 (4) ◽  
pp. 991-999 ◽  
Author(s):  
Dezhi Ning ◽  
Xuanlie Zhao ◽  
Ming Zhao ◽  
Haigui Kang
Keyword(s):  
Transmission Coefficient ◽  
Wave Energy ◽  
Wave Energy Converter ◽  
Hydrodynamic Performance ◽  
Width Ratio ◽  
Frequency Range ◽  
Effective Frequency ◽  
Energy Converter ◽  
Damping Force ◽  
Capture Width Ratio

As an extension of the single pontoon wave energy converter–type breakwater, a wave energy converter–type breakwater equipped with dual pontoon–power take-off system is proposed to broaden the effective frequency range (for transmission coefficient KT < 0.5 and capture width ratio η > 20%). The wave energy converter–type breakwater with dual pontoon–power take-off system consists of a pair of heave-type pontoons and power take-off systems for which the power take-off system is installed to harvest the kinetic energy of heave motion of the pontoon. In this paper, we experimentally confirm the advantage of the wave energy converter–type breakwater with dual pontoon–power take-off system over the one with a single pontoon–power take-off system. Both wave energy converter–type breakwater with dual pontoon–power take-off system and that with single pontoon–power take-off system are tested in regular waves. A (electronic) current controller–magnetic powder brake system is used to simulate the power take-off system. The characteristics of power take-off system are investigated and results showed that the power take-off system can simulate the (approximate) Coulomb damping force well. Experimental results reveal that the wave energy converter–type breakwater with dual pontoon–power take-off system broadens the effective frequency range compared with the single pontoon–power take-off system with the same pontoon volume (i.e. the displacement of the pontoon). Specifically, the transmission coefficient of the system is smaller while the system in relative longer waves. Furthermore, the capture width ratio of system can be improved.

scholarly journals Development and evaluation of a highly adaptive MRF-based absorber with a large effective frequency range

2019 ◽  
Vol 28 (10) ◽  
pp. 105003
Author(s):  
J Yang ◽  
S S Sun ◽  
D Ning ◽  
Z Li ◽  
L Deng ◽  
...  
Keyword(s):  
Frequency Range ◽  
Effective Frequency

Adaptive Tuned Dynamic Vibration Absorber With Variable Stiffness Property Using Magneto-Rheological Elastomers

2013 ◽  
Author(s):  
Toshihiko Komatsuzaki ◽  
Yoshio Iwata ◽  
Hirofumi Ringe ◽  
Keiji Kawagoshi
Keyword(s):  
Variable Stiffness ◽  
Vibration Absorber ◽  
Frequency Range ◽  
Magnetorheological Elastomer ◽  
Effective Frequency ◽  
Dynamic Vibration Absorber ◽  
Dynamic Vibration ◽  
Narrow Frequency Range ◽  
Dynamic Absorber ◽  
Magneto Rheological

A passive type dynamic vibration absorber offers advantages in reliability and simple constitution, however, the use of the absorber with fixed property is usually limited to harmonically excited case, where the damper is only effective for pre-determined narrow frequency range. Design of the damper following well-known optimal tuning theory could extend the effective frequency range, yet the damping performance remains at a certain amount. In this paper, the stiffness controllable elastomer composite known as Magnetorheological elastomer (MRE) is applied to the dynamic absorber whose natural frequency is tunable by the external magnetic field. MREs are first fabricated and their field-dependent properties are investigated. The MRE is then applied to a dynamic absorber along with stiffness switching scheme so that the vibration of 1-DOF structure is damped more effectively. Investigations show that the vibration of the structure can be fully reduced by the proposed dynamic absorber with variable stiffness functionality.

Application of orthogonalization methods of pseudospectra of steps for human identification

2021 ◽  
Author(s):  
E.A. Chernetsova ◽  
◽  
A.V. Gomera ◽  
T.M. Tatarnikova ◽  
Keyword(s):  
Remote Access ◽  
Acoustic Vibrations ◽  
Frequency Diversity ◽  
Biometric System ◽  
Frequency Range ◽  
Audio Signals ◽  
Effective Frequency ◽  
Classification Procedure ◽  
Access Control System ◽  
Foot Position

A method for processing audio signals of steps of various people in order to effectively separate pseudospectra of signals that can be further subjected to the classification procedure is proposed. The model of a human steps detector was based on the dynamic parameters of the foot position when walking. To record step signals, vibroacoustic sensors were used, sensitive to mechanical and acoustic vibrations in the frequency range from 10 to 1000 Hz. The processing of recorded step signals involved calculating their envelope and then calculating the pseudospectra of the envelope. The procedure for orthogonalization of the pseudospectra of steps for their effective frequency diversity can be used as the basis for the operation of an automated Remote Access Control System. This system can find the application in areas where for one reason or another it is impossible to install another biometric system or is extremely inconvenient, for example, to control access to a room into which the working personnel enter in a special uniform, gloves, and goggles.

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