Fabrication and characterization of a force coupled sensor–actuator system for adjustable resonant low frequency vibration detection

2008 ◽  
Vol 145-146 ◽  
pp. 245-256 ◽  
Author(s):  
Roman Forke ◽  
Dirk Scheibner ◽  
Karla Hiller ◽  
Thomas Gessner ◽  
Wolfram Dötzel ◽  
...  
Keyword(s):  
Low Frequency ◽  
Sensor Actuator ◽  
Vibration Detection ◽  
Low Frequency Vibration ◽  
Actuator System ◽  
Fabrication And Characterization

Low Frequency Vibration Detection and Compensation in Hard Disk Drive

2011 ◽  
Vol 47 (7) ◽  
pp. 1964-1969 ◽  
Author(s):  
Wen-Jun Cao ◽  
JianYi Wang ◽  
MingZhong Ding ◽  
Qiang Bi ◽  
KianKeong Ooi
Keyword(s):  
Hard Disk Drive ◽  
Low Frequency ◽  
Hard Disk ◽  
Disk Drive ◽  
Vibration Detection ◽  
Low Frequency Vibration

Dynamic Response of Normal and Osteoporotic Trabecular Bone by Vibration Analysis

2005 ◽  
Author(s):  
Wafa Tawackoli ◽  
Gemunu Gunaratne ◽  
Fazle Hussain ◽  
Michael Liebschner
Keyword(s):  
Treatment Efficacy ◽  
Low Frequency ◽  
Osteoporotic Fractures ◽  
Vibrational Modes ◽  
Response Signal ◽  
Noninvasive Sensors ◽  
Low Frequency Vibration ◽  
The Us ◽  
Monitoring Treatment

Osteoporosis afflicts about 200 million people worldwide; and osteoporotic fractures are in the millions annually in the US alone and cost tens of billions of dollars [1]. Characterization of bone quality in osteoporotic patients is important with respect to monitoring treatment efficacy, though currently quite limited. While some technical hurdles in developing a noninvasive diagnostic tool using low frequency vibration have been overcome, changes in the frequency response signal of bone have not been investigated at the various bone organizational levels. Our principal hypothesis is that the vibrational modes of bone tissue change significantly with the deterioration of bone micro-architecture and that these modes can be captured by noninvasive sensors.

A MEMS resonant accelerometer for low-frequency vibration detection

2018 ◽  
Vol 283 ◽  
pp. 151-158 ◽  
Author(s):  
Shudong Wang ◽  
Xueyong Wei ◽  
Yulong Zhao ◽  
Zhuangde Jiang ◽  
Yajing Shen
Keyword(s):  
Low Frequency ◽  
Vibration Detection ◽  
Low Frequency Vibration ◽  
Resonant Accelerometer

Design of Low-frequency Vibration Detection System

2014 ◽  
Vol 8 (1) ◽  
pp. 330-334
Author(s):  
Ding Ji-feng ◽  
Xu Shuang ◽  
Yang Ya-ning
Keyword(s):  
Embedded System ◽  
Interface Design ◽  
Detection System ◽  
Low Frequency ◽  
Vibration Signal ◽  
Wireless Transmission ◽  
Widespread Application ◽  
Display Module ◽  
Vibration Detection ◽  
Low Frequency Vibration

In order to improve the accuracy, feasibility and convenience of the vibration detection system, design a simple and practical low-frequency vibration detection system. This system is designed based on STM32 platform, composed of shaping circuit, the measurement of vibration signal, wireless transmission and TFT touch screen display module, μC/OS-II embedded system transplantation, miniGUI interface design, and finally realize the display of waveform and frequency of vibration signal. By testing this system, find that it is stable, reliable and real-time, basically reached the expected requirements and can be very good to meet the actual demand, which has a widespread application prospect.

Experimental Characterization of Synchronous Vibrations of Blades

2011 ◽  
Author(s):  
Juan C. Jauregui ◽  
Mihir Sen ◽  
Carlos S. Lopez-Cajun
Keyword(s):  
Weak Interactions ◽  
Low Frequency ◽  
Turbine Rotor ◽  
Time Intervals ◽  
Low Frequency Vibration ◽  
Time Period ◽  
Manufacturing Errors ◽  
Blade Tip ◽  
Medium Time

Blades in a turbine rotor synchronize their individual vibrations after a certain period of time. Each blade has a slightly different natural frequency due to manufacturing errors, and it responds individually to external excitations. Nevertheless, after a period of time the blades synchronize and vibrate at the same frequency due to weak interactions between them. In this work, experiments are reported that identify blade synchronization. Individual blade vibrations were measured simultaneously under different conditions. Measurements were made with accelerometers attached to the tip of each blade which were very light in comparison with the mass of the blade. The blades were first excited by an impact force and the natural frequencies were identified. Then, the blades were excited by airflow and individual blade-tip vibrations were recorded at several subsequent time intervals. Synchronization is analyzed through the correlation between the time responses of every blade. The correlation was calculated at each of these intervals and the results were plotted in maps. It was found that the synchronization evolves as a function of time; it is high after a medium time period and reduced at longer time periods. Thus blade synchronization presents a long wave variation that could be a source of a very low frequency vibration. It was also possible to say that synchronization is dominated by the structure of the rotor.

scholarly journals Hearing in the African lungfish ( Protopterus annectens ): pre-adaptation to pressure hearing in tetrapods?

2010 ◽  
Vol 7 (1) ◽  
pp. 139-141 ◽  
Author(s):  
Jakob Christensen-Dalsgaard ◽  
Christian Brandt ◽  
Maria Wilson ◽  
Magnus Wahlberg ◽  
Peter T. Madsen
Keyword(s):  
Sound Pressure ◽  
Low Frequency ◽  
West African ◽  
Low Frequencies ◽  
Frequency Responses ◽  
Protopterus Annectens ◽  
Vibration Detection ◽  
Low Frequency Vibration ◽  
African Lungfish ◽  
Early Tetrapods

Lungfishes are the closest living relatives of the tetrapods, and the ear of recent lungfishes resembles the tetrapod ear more than the ear of ray-finned fishes and is therefore of interest for understanding the evolution of hearing in the early tetrapods. The water-to-land transition resulted in major changes in the tetrapod ear associated with the detection of air-borne sound pressure, as evidenced by the late and independent origins of tympanic ears in all of the major tetrapod groups. To investigate lungfish pressure and vibration detection, we measured the sensitivity and frequency responses of five West African lungfish ( Protopterus annectens ) using brainstem potentials evoked by calibrated sound and vibration stimuli in air and water. We find that the lungfish ear has good low-frequency vibration sensitivity, like recent amphibians, but poor sensitivity to air-borne sound. The skull shows measurable vibrations above 100 Hz when stimulated by air-borne sound, but the ear is apparently insensitive at these frequencies, suggesting that the lungfish ear is neither adapted nor pre-adapted for aerial hearing. Thus, if the lungfish ear is a model of the ear of early tetrapods, their auditory sensitivity was limited to very low frequencies on land, mostly mediated by substrate-borne vibrations.

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