A Novel Accelerometer Mounting Method for Sensing Performance Improvement in Acoustic Measurements From the Knee

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Goktug C. Ozmen ◽  
Mohsen Safaei ◽  
Lan Lan ◽  
Omer T. Inan
Keyword(s):  
Frequency Band ◽  
High Frequency ◽  
Low Frequency ◽  
Adhesive Tape ◽  
Spectral Centroid ◽  
Wearable Systems ◽  
Electrodynamic Shaker ◽  
3D Printed ◽  
The Mean ◽  
Sensing Performance

Abstract In this study, we propose a new mounting method to improve accelerometer sensing performance in the 50 Hz–10 kHz frequency band for knee sound measurement. The proposed method includes a thin double-sided adhesive tape for mounting and a 3D-printed custom-designed backing prototype. In our mechanical setup with an electrodynamic shaker, the measurements showed a 13 dB increase in the accelerometer's sensing performance in the 1–10 kHz frequency band when it is mounted with the craft tape under 2 N backing force applied through low-friction tape. As a proof-of-concept study, knee sounds of healthy subjects (n = 10) were recorded. When the backing force was applied, we observed statistically significant (p < 0.01) incremental changes in spectral centroid, spectral roll-off frequencies, and high-frequency (1–10 kHz) root-mean-square (RMS) acceleration, while low-frequency (50 Hz–1 kHz) RMS acceleration remained unchanged. The mean spectral centroid and spectral roll-off frequencies increased from 0.8 kHz and 4.15 kHz to 1.35 kHz and 5.9 kHz, respectively. The mean high-frequency acceleration increased from 0.45 mgRMS to 0.9 mgRMS with backing. We showed that the backing force improves the sensing performance of the accelerometer when mounted with the craft tape and the proposed backing prototype. This new method has the potential to be implemented in today's wearable systems to improve the sensing performance of accelerometers in knee sound measurements.

scholarly journals Ferrite-Loaded Spidron Fractal Loop VHF Antenna for UAV Applications

2020 ◽  
Vol 10 (15) ◽  
pp. 5392 ◽  
Author(s):  
Won Bin Park ◽  
Young-Mi Park ◽  
Keum Cheol Hwang
Keyword(s):  
Frequency Band ◽  
High Frequency ◽  
Magnetic Loss ◽  
Low Frequency ◽  
Loop Antenna ◽  
High Frequency Band ◽  
Ferrite Material ◽  
Aerial Vehicle ◽  
Flat Ground ◽  
Good Agreement

In this letter, an electrically small Spidron fractal loop antenna operating in the VHF band is proposed. The ferrite material, which consists of a nickel-zinc combination, is loaded into inside of the loop antenna to increase the gain of the antenna in the low frequency band. To minimize the magnetic loss of the ferrite in the high frequency band, the amount and configuration of the ferrite are optimized using a genetic algorithm. Through this optimization step, the amount of the ferrite is decreased to 37.5% and the gain of the antenna in the high frequency band is improved. The size of the proposed antenna is 0.0242 × 0.0242 × 0.0051 λL3 at the lowest operating frequency. The proposed antenna was fabricated to verify the performance, and the simulated and measured results are in good agreement. The measured peak gains varied from −31.6 to −1.9 dBi within the measured frequency band. To examine the performance of the proposed antenna mounted on an unmanned aerial vehicle model (UAV), the antenna on a UAV was also simulated and the results were discussed. The simulated realized peak gains of the antenna on the UAV and on flat ground are similar.

Dual-band low-profile planar antenna for mobile communication application

2015 ◽  
Vol 9 (2) ◽  
pp. 447-452 ◽  
Author(s):  
Xi-Wang Dai ◽  
Tao Zhou ◽  
Bo-Ran Guan
Keyword(s):  
Frequency Band ◽  
Mobile Communication ◽  
High Frequency ◽  
Microstrip Line ◽  
Low Frequency ◽  
Dual Band ◽  
Planar Antenna ◽  
Frequency Resonance ◽  
Low Profile ◽  
High Frequency Resonance

A novel dual-band planar antenna with a low profile for mobile communication system is proposed in this paper. The antenna is composed of one shorted patch with two radiating notches for low frequency resonance and one square patch for high frequency resonance. The low profile is achieved via the shorting patch, which introduces the parallel electrical field between the reflector and antenna. A step-impedance microstrip line is used to feed the antenna. The coupling between the square patch and microstrip line cancels out the inductance of shorting probe, which increases the working bandwidth of proposed antenna. A prototype with a low profile of 0.0286λ is fabricated and measured. The antenna achieves dual impedance bandwidths of 1.6% for the low frequency band and 60% for the high frequency band, covering the frequency range 851–865 MHz and 1.97–3.65 GHz, respectively. The measured results show good agreements with the simulated ones.

Heart rate variability and dissociation in panic disorder

2011 ◽  
Vol 26 (S2) ◽  
pp. 147-147
Author(s):  
T. Diveky ◽  
D. Kamaradova ◽  
A. Grambal ◽  
K. Latalova ◽  
J. Prasko ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Panic Disorder ◽  
Frequency Band ◽  
High Frequency ◽  
Power Spectra ◽  
Low Frequency ◽  
Very Low Frequency ◽  
Significant Difference ◽  
Before And After

The aim of our study is to measure very low frequency band (VLF), low frequency band (LF) and high frequency band (HF) components of R-R interval during orthostatic experiment in panic disorder patients before and after treatment.MethodsWe assessed heart rate variability in 19 patients with panic disorder before and after 6-weeks treatment with antidepressants combined with CBT and 18 healthy controls. They were regularly assessed on the CGI, BAI and BDI. Heart rate variability was assessed during 5 min standing, 5 min supine and 5 min standing positions before and after the treatment. Power spectra were computed using a fast Fourier transformation for very low frequency - VLF (0.0033 - 0.04 Hz), low-frequency - LF (0.04-0.15 Hz) and high frequency - HF (0.15-0.40 Hz) powers.Results19 panic disorder patients entered a 6-week open-label treatment study with combination of SSRI and cognitive behavioral therapy. A combination of CBT and pharmacotherapy proved to be the effective treatment of patients. They significantly improved in all rating scales. There were highly statistical significant differences between panic patients and control group in all components of power spectral analysis in 2nd and in two component of 3rd (LF and HF in standing) positions. There was also statistically significant difference between these two groups in LF/HF ratio in supine position (2nd). During therapy there was tendency to increasing values in all three positions in components of HRV power spectra, but there was only statistically significant increasing in HF1 component.Supported by project IGA MZ ČR NS 10301-3/2009

Fusion Algorithm of Infrared and Visible Images Based on Multiresolution Decomposition

2012 ◽  
Vol 239-240 ◽  
pp. 229-232
Author(s):  
Chen Ding
Keyword(s):  
Statistical Model ◽  
Image Fusion ◽  
Frequency Band ◽  
High Frequency ◽  
Wavelet Coefficient ◽  
Low Frequency ◽  
High Frequency Band ◽  
Fusion Algorithm ◽  
Regional Energy ◽  
Multiresolution Decomposition

Information redundancy and complementarity are existing between the images obtained by multi-sensor, image fusion can improve the certainty and reliability of the information. Traditional method of image fusion based on multiresolution decomposition is susceptible to high frequency noise, fusion is often ineffective. A image fusion algorithm has been studied based on the wavelet multiresolution decomposition which is regional energy maximum for low-frequency decomposition image, and the bivariate statistical model for high-frequency part. The results show that: in the conditions of Daubechies 3 wavelet basis function, decomposition level 5 multiresolution decomposition, the bivariate statistical model for the high-frequency band is robust to noise based on the joint probability of wavelet coefficient pair - a wavelet coefficient and its parent; in the same time, the regional energy maximum for low-frequency band can be effective on the high-frequency band based on the bivariate statistical model. The fusion image has the biggish contrast, the preferable details, the higher gray level resolution.

scholarly journals Acoustical study on spectral characteristics of teachers’ English vocalization

2021 ◽  
Vol 257 ◽  
pp. 02027
Author(s):  
Yao Xiao ◽  
Yue-Zhe Zhao
Keyword(s):  
Frequency Band ◽  
High Frequency ◽  
Sound Pressure ◽  
Spectral Characteristics ◽  
Low Frequency ◽  
Sound Intensity ◽  
English Teaching ◽  
Female Teachers ◽  
Acoustical Study ◽  
Second Peak

With the increase of English teaching courses, the specific vocal characteristics of teachers in English teaching are studied and used as the basic data for the design of teachers’ spatial acoustics. In order to study this problem, three different English voice materials were read in a anechoic room under three sound intensity levels: large, medium and small, respectively, so as to analyse the equivalent continuous sound pressure level (SPL) and frequency characteristic curves of male and female teachers at 0.3m. In the low frequency band, the SPL increases as the frequency increases. In the mid-frequency band, the SPL reaches the first peak, then decreases briefly as the frequency increases, then increases again to the second peak, and then decreases again briefly as the frequency increases. Then increase again to the third peak. In the high frequency band, the SPL decreases as the frequency increases.

scholarly journals Краевые колебания нанолент графана

2018 ◽  
Vol 60 (5) ◽  
pp. 1029
Author(s):  
А.В. Савин
Keyword(s):  
Force Field ◽  
Frequency Spectrum ◽  
High Frequency ◽  
Low Frequency ◽  
Dispersion Curves ◽  
Linear Vibrations ◽  
The Mean

AbstractUsing the COMPASS force field, natural linear vibrations of graphane (graphene hydrogenated on both sides) nanoribbons are simulated. The frequency spectrum of a graphane sheet consists of three continuous intervals (low-frequency, mid-frequency, and narrow high-frequency) and two gaps between them. The construction of dispersion curves for nanoribbons with a zigzag and chair structure of the edges show that the frequencies of edge vibrations (edge phonons) can be present in the gaps of the frequency spectrum. In the first type of nanoribbons, two dispersion curves are in the low-frequency gap of the spectrum and four dispersion curves in the second gap. These curves correspond to phonons moving only along the nanoribbon edges (the mean depth of their penetration toward the nanoribbon center does not exceed 0.15 nm).

scholarly journals Vibration Attenuation Investigations on a Distributed Phononic Crystals Beam for Rubber Concrete Structures

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Chao Li ◽  
Sifeng Zhang ◽  
Liyong Gao ◽  
Wei Huang ◽  
Zhaoxin Liu
Keyword(s):  
Band Gap ◽  
Frequency Band ◽  
High Frequency ◽  
Concrete Beam ◽  
Vibration Isolation ◽  
Civil Engineering ◽  
Low Frequency ◽  
Band Gaps ◽  
Spring Force ◽  
Rubber Concrete

Locally resonant phononic crystals (LRPCs) beam is characterized by the band gaps; some frequency ranges within which flexural waves cannot propagate freely. So, the LRPCs beam can be used for noise or vibration isolation. In this paper, a LRPCs beam with distributed oscillators is proposed, and the general formula of band gaps and transmission spectrum are derived by the transfer matrix method (TMM) and spectrum element method (SEM). Subsequently, the parameter effects on band gaps are investigated in detail. Finally, a rubber concrete beam is designed to demonstrate the application of distributed LRPCs beam in civil engineering. Results reveal that the distributed LRPCs beam has multifrequency band gaps and the number of the band gaps is equal to that of the oscillators. Compared with others, the distributed LRPCs beam can reduce the stress concentration when subjected to vibration. The oscillator interval has no effect on the band gaps, which makes it more convenient to design structures. Individual changes of oscillator mass or stiffness affect the band gap location and width. When the resonance frequency of oscillator is fixed, the starting frequency of the band gap remains constant, and increasing oscillator mass of high-frequency band gap widens the high-frequency band gap, while increasing oscillator mass of low-frequency gap widens both high-frequency and low-frequency band gaps. External loads, such as the common uniform spring force provided by foundation in civil engineering, are conducive to the band gap, and when the spring force increases, all the band gaps are widened. Taken together, a configuration of LRPCs rubber concrete beam is designed, and it shows good isolation on the vibration induced by the railway. By the presented design flow chart, the research can serve as a reference for vibration isolation of LRPCs beams in civil engineering.

scholarly journals Mechanistic Characteristics of Double Dominant Frequencies of Acoustic Emission Signals in the Entire Fracture Process of Fine Sandstone

Energies ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3959 ◽  
Author(s):  
Chuangye Wang ◽  
Xinke Chang ◽  
Yilin Liu ◽  
Shijiang Chen
Keyword(s):  
Frequency Band ◽  
High Frequency ◽  
Fracture Process ◽  
Low Frequency ◽  
High Amplitude ◽  
Dominant Frequency ◽  
Band Energy ◽  
Ae Signal ◽  
Low Amplitude ◽  
Frequency Band Energy

To determine the intrinsic relationship between the acoustic emission (AE) phenomenon and the fracture pattern pertaining to the entire fracture process of rock, the present paper proposed a multi-dimensional spectral analysis of the AE signal released during the entire process. Some uniaxial compression AE tests were carried out on the fine sandstone specimens, and the axial compression stress–strain curves and AE signal released during the entire fracture process were obtained. In order to deal with tens of thousands of AE data efficiently, a subroutine was programmed in MATLAB. All AE waveforms of the tests were denoised by wavelet threshold firstly. The fast Fourier transform (FFT) and wavelet packet transform (WPT) were applied to the denoised waveforms to obtain the dominant frequency, amplitude, fractal, and frequency band energy ratio distribution. The results showed that the AE signal in the entire fracture process of fine sandstone had a double dominant frequency band of the low and high-frequency bands, which can be subdivided into low-frequency low-amplitude, high-frequency low-amplitude, high-frequency high-amplitude, and low-frequency high-amplitude signals, according to the magnitude. The low-frequency amplitude relevant fractal dimension and the high-frequency amplitude relevant fractal dimension each had turning points that corresponded to significant decreases in the middle and end stages of loading, respectively. The frequency band energy was mainly concentrated in the range of 0–187.5 kHz, and the energy ratios of some bands had different turning points, which appeared before the complete failure of the rock. It is suggested that the multi-dimensional spectral analysis may understand the failure mechanism of rock better.

Herzfrequenzvariabilität als Indikator des Aufmerksamkeitsfokus bei Golfern unterschiedlichen Leistungsniveaus

2012 ◽  
Vol 19 (1) ◽  
pp. 26-36
Author(s):  
Thomas Finkenzeller ◽  
Michael Doppelmayr ◽  
Günter Amesberger
Keyword(s):  
Frequency Band ◽  
High Frequency ◽  
Low Frequency ◽  
High Frequency Band

Aufmerksamkeitsprozesse, die sowohl für das Erlernen als auch für das optimale Ausführen von Bewegungen von zentraler Bedeutung sind, können an Sportarten wie Golf psychophysiologisch mittels Kenngrößen wie Herzfrequenzvariabilität (HRV) erfasst werden. Ziel dieser Studie ist es zu prüfen, ob sich Kennwerte der HRV von Golf-Experten (n = 12), fortgeschrittenen Golfern (n = 12) und Novizen (n = 11) während der Putt-Ausführung unterscheiden und ob es mit Fortdauer der Putt-Aufgabe zu HRV-Veränderungen kommt. Während aufeinander folgender Putt-Serien absolvierten die Probanden jeweils zehn Putts. Die Experten und Fortgeschrittenen unterscheiden sich signifikant von den Novizen im low frequency-Band (0.04 – 0.15 Hz) und im Verhältnis von low frequency zu high frequency-Band (0.15 – 0.40 Hz). Die HRV-Kennwerte verändern sich nicht mit Fortdauer der Putt-Serien. Die Unterschiede im LF-Band, die bereits bei Golfern mit mäßigem Niveau auftreten, werden als Ausdruck eines externalen Aufmerksamkeitsfokus interpretiert.

A generalized mean-field model of the natural and high-frequency actuated flow around a high-lift configuration

2009 ◽  
Vol 623 ◽  
pp. 283-316 ◽  
Author(s):  
DIRK M. LUCHTENBURG ◽  
BERT GÜNTHER ◽  
BERND R. NOACK ◽  
RUDIBERT KING ◽  
GILEAD TADMOR
Keyword(s):  
High Frequency ◽  
Field Model ◽  
Mean Field ◽  
Low Frequency ◽  
Navier Stokes ◽  
Mean Field Model ◽  
High Lift ◽  
The Mean ◽  
Generalized Mean ◽  
Low Dimensional

A low-dimensional Galerkin model is proposed for the flow around a high-lift configuration, describing natural vortex shedding, the high-frequency actuated flow with increased lift and transients between both states. The form of the dynamical system has been derived from a generalized mean-field consideration. Steady state and transient URANS (unsteady Reynolds-averaged Navier–Stokes) simulation data are employed to derive the expansion modes and to calibrate the system parameters. The model identifies the mean field as the mediator between the high-frequency actuation and the low-frequency natural shedding instability.

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