Papers by Keyword: Low Frequency

Abstract: This work is devoted to modeling of physical subsystem, considering an electromagnetic exciter of low-frequency oscillations (EME LFO) as it, which is a classic example of an electromechanical system. For the simulation of electromagnetic exciter of low frequencies Simscape was chosen. Based on the principle of operation (reciprocating motion due to the configuration of the resonance circuit), and the structure of the apparatus, there is detected the operation character with several types of energy conversion: electrical to magnetic and magnetic to mechanical. And the main requirement to the developed model is the conservation of energy and power under the corresponding transformations.

Abstract: Performance of optical table with pneumatic vibration isolators is analyzed within 2–50 Hz frequency range. Specific vibrational excitation platform with a vibrator of the frequency range of 1–50 Hz in one of three directions were tested.The following pneumatic vibration isolator dynamic parameters were identified:transmissibility of vertical oscillation characteristics at 50 Hz frequency range;resonant frequency (vertical direction);damping efficiency at 5 Hz to 10 Hz for excitation frequencies.

Abstract: The low frequency voltage controlled oscillator (VCO) is designed using integrated operational amplifier. The frequency of the output signal of VCO changes with the magnitude of the input signal voltage, and show a linear relationship within a certain range through the experimental test. Experiments show that, under the input of certain amplitude and frequency range of the square wave, triangle wave, saw-tooth wave, the output waveform of VCO respectively is ambulance, fire siren and other kinds of ambulance siren Signal. This innovative design’ cost is low, realized by analog circuit. It can be used in the practice of teaching case, electronic production or development of sound panels.

Abstract: This paper presents a prototype of a new flextensional transducer with PVDF (Polyvinylidene Fluoride) piezoelectric film instead of metallic shell. Resonance frequency, bandwidth, transmitting voltage response, and horizontal directivity of the flextensional transducer with PVDF piezoelectric film were respectively measured by using laser-scanning vibrometer, and underwater acoustic measurement system. Experimental results showed that the new transducer features effectively conversion from longitudinal vibration of piezoelectric stack into radial vibration of PVDF piezoelectric film.

Abstract: In order to generate low frequency acoustic wave and minish the ratio of the length to diameter, it is appropriate to instead the circular jet by annular jet as the high pressure gas power. So the larger diameter of jet and resonator are got in the condition of the same pressure and flux. Flow simulations and experiments have been performed in order to better understand the behavior of the powered resonance tube (PRT) driven by annular. Simulation and experiment results show the PRT can be excited by a annular jet, and produce low frequency high-amplitude dynamic pressures and acoustic emission. The compression wave and expansion wave transmit into and out of the resonance tube alternately in a cycle and a cycle can be decomposed to two distinct stages of filling and evacuation. In experiment PRT can work in the low frequency at very low pressure, and PRT can generate intense sound wave at frequency from 50~3200Hz.

Abstract: In this work is presented a study of a piezoelectric energy harvesting device used for low power consumption applications operating at relative low frequency. The structure consists of a cantilever beam made by Lead Zirconate Titanate (PZT) layer with two gold electrodes for electrical contacts. The piezoelectric material was selected taking into account its high coupling coefficients. Different structures were analyzed with variations in its dimensions and shape of the cantilever. The devices were designed to operate at the resonance frequency to get maximum electrical power output. The structures were simulated using finite element (FE) software. The analysis of the harvesting devices was performed in order to investigate the influence of the geometric parameters on the output power and the natural frequency. To validate the simulation results, an experiment with a PZT cantilever with brass substrate was carried out. The experimental data was found to be very close to simulation data. The results indicate that large structures, in the order of millimeters, are the ideal for piezoelectric energy harvesting devices providing a maximum output power in the range of mW

Abstract: Piezoelectric motor under low frequency with multi-DOF rotation is issued. The establishment of single vibration mode piezoelectric motor static characteristic and dynamic characteristics is complemented, and the structure and characteristics of low frequency drive is proposed.

Abstract: Methods which are MVDR beam-forming, STMV beamforming and a method using MVDR beamforming with copy correlation are using to measure highlight of targets echoes at low frequency. Compared with conventional beam-forming, the three methods restrain noise and resist reverberation better. To reduce calculation, firstly, as the azimuth measured by using Split array cross-correlation beamforming the center, and then the neighboring area scanned using MVDR focused beamforming. Therefore, this highlight of echoes research measures have high precision and practical.

Abstract: In view of the existing of low frequency hydrophone in signal detection problems such as low sensitivity, frequency range is small, In this paper, application of PVDF piezoelectric film as sensitive material of low frequency hydrophone, use its advantages as fast response, high sensitivity, good mechanical properties, and so on [1], designed a kind of low frequency hydrophone, experiments are carried out to study the detection of low frequency signal. This paper introduces the structure, material and size of the hydrophone, and analyzes the experimental data. Experiments show that the sensor stability and high sensitivity, can effectively detect the low frequency acoustic wave in the water.

Abstract: The development and utilization of different structural materials, optimization of the cantilever geometry and power harvesting circuit are the most commonly methods used to increase the power density of MEMS energy harvester. This paper discusses the cantilever geometry optimization process of low power and low frequency of bimorph MEMS energy harvester. Three piezoelectric materials, ZnO, AlN and PZT are deposited on top and bottom of the cantilever Si substrate. This study focuses on the optimization of the cantilevers length, width, substrate thickness and PZe thickness in order to achieve lower than 600 Hz of resonant frequency. The harvested power for this work is in the range of 0.02 ~ 194.49 nW.