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.

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.

A Study on the Fine Structure of the Lateral Line Organ of the Sea Eel

1973 ◽  
Vol 31 ◽  
pp. 648-649
Author(s):  
K. Hama
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Lateral Line ◽  
Low Frequency ◽  
Sensory Cells ◽  
Apical Surface ◽  
Voltage Electron ◽  
Sensory Epithelia ◽  
Low Frequency Vibration ◽  
Transmission Electron

The lateral line organs of the sea eel consist of canal and pit organs which are different in function. The former is a low frequency vibration detector whereas the latter functions as an ion receptor as well as a mechano receptor.The fine structure of the sensory epithelia of both organs were studied by means of ordinary transmission electron microscope, high voltage electron microscope and of surface scanning electron microscope.The sensory cells of the canal organ are polarized in front-caudal direction and those of the pit organ are polarized in dorso-ventral direction. The sensory epithelia of both organs have thinner surface coats compared to the surrounding ordinary epithelial cells, which have very thick fuzzy coatings on the apical surface.

scholarly journals Low frequency vibrational modes of oxygenated myoglobin, hemoglobins, and modified derivatives.

1994 ◽  
Vol 269 (49) ◽  
pp. 31047-31050
Author(s):  
S Jeyarajah ◽  
L M Proniewicz ◽  
H Bronder ◽  
J R Kincaid
Keyword(s):  
Low Frequency ◽  
Vibrational Modes
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