scholarly journals Identification of Pyrotechnic Shock Sources for Shear Type Explosive Bolt

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Yanhua Li ◽  
Shihui Xiong ◽  
Yuan Li ◽  
Xiaogang Li ◽  
Yuquan Wen ◽  
...  
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Shock Source ◽  
Propellant Combustion ◽  
Relative Contribution ◽  
Shear Type ◽  
The Mean ◽  
Weak Surface ◽  
Response Output ◽  
Piston Stroke

To identify the shock generated sources of shear type explosive bolt, five kinds of explosive bolts with different states, including high preload, low preload, no preload, no piston shear, and only propellant combustion, were designed. The decoupling of four kinds of shock sources, including the collision of propellant combustion, piston shear weak surface, end of piston stroke, and preload release, was realized. Their acceleration responses at 15 cm from the shock source center on 60 cm × 60 cm × 1 cm equivalent aluminum plate were measured by using the piezoresistive accelerometer. On this account, the relative contribution values along with frequency and the mean relative values without regard to frequency of various sources were calculated in high and low preload. Results show that the characteristics of different shock sources are different, and the shock induced by propellant combustion is mainly caused by high frequency, while piston shear and piston impact are concentrated in medium and low frequency. In the high preload condition, the preload release is major contributor to the overall shock response output, accounting for approximately 57.51%, while the contributions of the three shock sources of propellant combustion, piston shear, and piston impact are equivalent, but they are significant contributors in the low preload condition. This study provides design reference to reduce the pyrotechnic shock of shear type explosive bolt.

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 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).

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.

scholarly journals Evolution of low-frequency contribution in emission of steep-spectrum radio sources

2014 ◽  
Vol 11 (S308) ◽  
pp. 631-635
Author(s):  
Alla P. Miroshnichenko
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Radio Spectrum ◽  
Unified Model ◽  
Linear Size ◽  
Radio Sources ◽  
Mean Values ◽  
Spectrum Radio ◽  
Size Characteristic ◽  
The Mean

AbstractWe consider evolution properties of galaxies and quasars with steep radio spectrum at the decametre band from the UTR-2 catalogue. The ratios of source's monochromatic luminosities at the decametre and high-frequency bands display the dependence on the redshift, linear size, characteristic age of examined objects. At that, the mean values of corresponding ratios for considered galaxies and quasars have enough close quantities,testifying on the unified model of sources. We analyse obtained relations for two types of steep-spectrum sources (with linear steep spectrum (S) and low-frequency steepness after a break (C+)) from the UTR-2 catalogue.

scholarly journals Influence of Autonomic Control on the Specific Intermittent Performance of Judo Athletes

2018 ◽  
Vol 64 (1) ◽  
pp. 99-109
Author(s):  
Bruno T. Campos ◽  
Eduardo M. Penna ◽  
João G.S. Rodrigues ◽  
Mateus Diniz ◽  
Thiago T. Mendes ◽  
...  
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Training Experience ◽  
Specific Performance ◽  
Before And After ◽  
Post Test ◽  
Judo Athletes ◽  
The Mean ◽  
Hrv Analysis ◽  
Different Levels

Abstract Judo is a high-intensity intermittent combat sport which causes cardiac adaptations both morphologically and related to the autonomic nervous system (ANS). Therefore, this study aims to verify the correlation between heart rate variability (HRV) at rest with performance in the Special Judo Fitness Test (SJFT) and whether groups with different RR values at rest show different performance in the SJFT and during post-test recovery. Sixteen judo athletes with 7.2 ± 3.9 years of training experience participated in the study. Before and after the SJFT execution HRV and lactate measurements were conducted. For HRV analysis, we used the mean interval RR, the standard deviation of the RR interval (SDNN), the root mean square of successive differences in RR intervals (RMSSD), the low frequency (LF) and high frequency (HF) in normalized and absolute units. The sample was split into two groups (low RR and high RR) to verify if this variable could differentiate between specific performance. For the SDNN, a significant and moderate correlation (r = 0.53) was found with the total number of throws and throws in the series A (r = 0.56) and B (r = 0.54) and for the RMSSD a correlation with throws during series B (r = 0.59) in the SJFT. However, the groups did not differ in performance and recovery. Therefore, HRV is related to intermittent judo performance; however, it cannot differentiate between judokas at different levels of performance.

scholarly journals High-Frequency Conductive Hearing following Total Drum Replacement Tympanoplasty

2020 ◽  
Vol 162 (6) ◽  
pp. 914-921 ◽  
Author(s):  
Marc D. Polanik ◽  
Danielle R. Trakimas ◽  
Nicole L. Black ◽  
Jeffrey T. Cheng ◽  
Elliott D. Kozin ◽  
...  
Keyword(s):  
High Frequency ◽  
Care Center ◽  
Tertiary Care ◽  
Surgical Techniques ◽  
Case Series ◽  
Low Frequency ◽  
Temporalis Fascia ◽  
The Mean ◽  
Hearing Outcomes ◽  
Conductive Hearing

Objectives Conventional reporting of posttympanoplasty hearing outcomes use a pure-tone averaged air-bone gap (ABG) largely representing a low-frequency sound conduction. Few studies report high-frequency conductive hearing outcomes. Herein, we evaluate high-frequency ABG in patients following temporalis fascia total drum replacement. Study Design Case series with chart review. Setting Tertiary care center. Subjects and Methods All patients who underwent type 1 tympanoplasty using a lateral graft total drum replacement technique between August 2016 and February 2019 were identified. Patients with pre- and postoperative audiograms were included. Low-frequency ABG was calculated as the mean ABG at 250, 500, and 1000 Hz. High-frequency ABG was calculated at 4 KHz. Pre- and postoperative ABGs were compared. Results Twenty-three patients were included, and the mean age at surgery was 44 years (range, 9-68 years). Perforation etiology was from trauma (n = 14) or chronic otitis media (n = 9). Preoperative mean low-frequency ABG was 27.8 ± 12.6 dB and mean high-frequency ABG was 21.5 ± 15.1 dB ( P = .044). Postoperatively, the mean low-frequency ABG was significantly reduced by 15.5 ± 13.3 dB ( P < .001) while the mean high-frequency ABG insignificantly changed (reduced by 2.6 ± 16.2 dB, P = .450). Conclusion In a series of patients undergoing temporalis fascia total drum replacement, low-frequency ABG improved; however, high-frequency conductive hearing loss persists. Conventional methods of reporting ABG may not identify persistent high-frequency ABG. These results merit further study across a range of tympanoplasty graft materials and surgical techniques.

Potentiation of transmission at Ia-motoneuron connections induced by repeated short bursts of afferent activity

1985 ◽  
Vol 54 (6) ◽  
pp. 1541-1552 ◽  
Author(s):  
B. M. Davis ◽  
W. F. Collins ◽  
L. M. Mendell
Keyword(s):  
High Frequency ◽  
Afferent Fiber ◽  
Low Frequency ◽  
Mean Amplitude ◽  
Medial Gastrocnemius ◽  
Epsp Amplitude ◽  
Ia Afferent ◽  
Enhanced Transmission ◽  
Test Stimulation ◽  
The Mean

Single medial gastrocnemius Ia-afferent fibers and motoneurons to which they projected were simultaneously impaled in anesthetized cats. Each Ia-afferent fiber was electrically stimulated once every 2 s with short high-frequency bursts (32 shocks at 167 Hz) followed by 1-11 test shocks. The resulting motoneuron excitatory postsynaptic potentials (EPSPs) were recorded and averaged in register. The interval between the end of one burst and the beginning of the next was 2 s; therefore, the amplitude of the first EPSP in the burst was considered to be a measure of efficacy of transmission 2 s after the burst. At most connections (23/29) the mean amplitude of the first EPSP in the burst was equal to or larger than the mean amplitude of control EPSPs produced by low-frequency (18-Hz) stimulation. Enhancement of transmission was maximum 50-100 ms after the burst, and the amplitude of the test EPSP delivered at this time was always greater than that of the control. The period of enhanced transmission appeared to decay more rapidly at connections with small EPSPs. The greatest amount of EPSP amplitude enhancement at 50 or 100 ms after the burst was observed at connections at which EPSP amplitude increased during the burst. The shape (rise time, half width) of potentiated EPSPs was the same as control EPSPs averaged during low-frequency (18-Hz) stimulation. Multiple shocks delivered at low frequency between bursts revealed that enhanced transmission following the high-frequency burst is very sensitive to the effects of low-frequency test stimulation. Furthermore, increasing the number of shocks during the interval between bursts reduced the enhancement of the first EPSP in the burst. We suggest that modulation of synaptic transmission after high-frequency bursts differs across Ia-motoneuron connections. These time-dependent changes associated with short bursts of firing (which are similar in frequency to those observed in Ia-fibers supplying hind-limb muscles during stepping) emphasize the necessity to consider the history of the discharge pattern of the group Ia fiber in assessing efficacy at individual Ia-motoneuron connections.

Abstract P399: The Relationship Between Heart Rate Variability and Common Carotid Artery Intima-media Thickness. The ELSA-Brasil

Circulation ◽  
2020 ◽  
Vol 141 (Suppl_1) ◽  
Author(s):  
Rosangela Hoshi ◽  
Paulo A LOTUFO ◽  
Itamar S Santos ◽  
Alessandra C Goulart ◽  
Jose-Geraldo Mill ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Carotid Artery ◽  
Common Carotid Artery ◽  
High Frequency ◽  
Low Frequency ◽  
Intima Media Thickness ◽  
Media Thickness ◽  
The Mean ◽  
The Relationship

Background: Both conditions as a more width common carotid artery intima-media thickness (cIMT), and a low heart rate variability (HRV) have been associated with cardiovascular health-adverse outcomes. Although previous studies have somehow explored the relationship between these markers, they have not credited the influences exerted by factors such as aging, demographics, and lifestyle variables. Aim: to investigate whether cardio autonomic alterations are accompanied or not by subclinical atherosclerosis, in apparently healthy men and women aged 35 to 74 years-old examined at the baseline of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil). Methods: The Heart Rate Variability was evaluated on 5-min segments of beat-to-beat heart rate recordings using linear time and frequency domain analyses. The c-IMT images were performed using a Toshiba (Aplio XG™) with a 7.5 MHz linear transducer. The c-IMT was measured in the outer wall during three cardiac cycles. The images were analyzed with specific software (MIA™, Coralville, IA). For this study, c-IMT was defined as the average between the mean left and mean right c-IMT values, and it was analyzed as a continuous and categorized variable (P<75 or P >= 75). Multiple linear models using continuous variables and multivariate logistic regression with categorized cIMT and HRV quartiles were performed. Results: Out of 7,201 participants eligible for analyses, 1,685 (23.4%) presented cIM >= 75th percentile. We found significantly reduced HRV variables in subjects with cIMT>=P75 in comparison to those with cIMT<P75: standard deviation of NN interval (SDNN) 33.0 ms vs. 37.0ms( P< 0.001); root of the mean of the sum of the squares of differences between adjacent NN intervals (RMSSD) 22.0 ms vs. 26.0ms (P< 0.001); Low-Frequency 191.0ms 2 vs. 260.0ms 2 ( P< 0.001); High-Frequency 164.0 ms 2 vs. 238.5ms 2 ( P< 0.001). In a crude analysis, an increased Odds Ratio (OR)and 95% Confidence Intervals for cIMT >=P75 was verified within the lowest two quartiles of Low-Frequency:1st quartile, OR = 1.75 (95%CI: 1.39 to 2.19); 2nd quartile, OR= 1.53 (1.25 to 1.87).The same was observed for High-Frequency:1st quartile, OR = 1.94 (1.38 to 2.73); 2nd quartile, OR= 1.60 (1.20 to 2.15). However, those associations did not remain after adjustments for anthropometric and clinical variables for Low-Frequency (1st quartile, OR= 1.08 (0.83 to 1.40); 2nd quartile, OR= 1.22 (0.97 to1.55), and for High Frequency, 1st quartile, OR= 1.16 (0.77 to 1.73); 2nd quartile, OR= 1.17 (0.83 to 1.64). Conclusions: Subjects with cIMT greater or equal to 75th percentile presented lower HRV values. However, no independent relationships were detected between cIMT and HRV after multivariate adjustment, suggesting that they may assess different and complementary domains and provide relevant, useful, and non-redundant information of cardiovascular risk.

Effect of hot arm and foot bath on heart rate variability and blood pressure in healthy volunteers

2019 ◽  
Vol 17 (1) ◽  
Author(s):  
Samruddhi Chintaman Vyas ◽  
A. Mooventhan ◽  
N. K. Manjunath
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Heart Rate Variability ◽  
Healthy Volunteers ◽  
High Frequency ◽  
Low Frequency ◽  
Healthy Male ◽  
Before And After ◽  
Instantaneous Heart Rate ◽  
The Mean

AbstractBackgroundThough hot arm and foot bath (HAFB) is widely used, a precise physiological response is not reported. Hence, the present study was conducted to evaluate the effect of HAFB on heart rate variability (HRV) and blood pressure (BP) in healthy volunteers.Materials and MethodsSixteen healthy male volunteers’ aged 23.81 ± 5.27 (mean ± standard deviation) years were recruited. All the subjects underwent only one session of HAFB (104-degree Fahrenheit) for the duration of 20 min. Assessments such as Electrocardiography and BP were taken before and after the intervention.ResultsResults of this study showed a significant reduction in systolic-BP (SBP), diastolic-BP (DBP), mean arterial pressure (MAP), the mean of the intervals between adjacent QRS complexes or the instantaneous heart rate (RR interval), the number of interval differences of successive NN intervals greater than 50 ms (NN50), the proportion derived by dividing NN50 by the total number of NN intervals (pNN50), and high frequency (HF) band of HRV along with a significant increase in heart rate (HR), low-frequency (LF) band of HRV and LF/HF ratio compared to its baseline.ConclusionsResults of this study suggest that 20 min of HAFB produce a significant increase in HR and a significant reduction in SBP, DBP, and MAP while producing parasympathetic withdrawal.

Dynamic Textures Retrieval Using the Integrated Wavelet-Based Surfacelet Transform

2012 ◽  
Vol 263-266 ◽  
pp. 227-230
Author(s):  
Zhi Yong An ◽  
Pei Qiang Liu ◽  
Hai Lan Jiang
Keyword(s):  
High Frequency ◽  
Local Binary Pattern ◽  
Texture Feature ◽  
Low Frequency ◽  
Dynamic Texture ◽  
Directional Filter ◽  
Spatial Features ◽  
Surfacelet Transform ◽  
The Mean ◽  
Frequency Features

To reduce the redundancy, a new integrated wavelet-based surfacelet transform(WBST) is proposed. The integrated WBST is constructed by combining the integrated 3D non-redundant wavelet with nonsubsampled directional filter banks. For 3D non-redundant wavelet transform, there are seven high frequency sub-bands and one high frequency sub-bands. Therefore, we design the integrated scheme with three high frequency sub-bands. In order to get the texture-spatial features, 3D local binary pattern (3D LBP) is used to describe the dynamic texture feature of low frequency sub-band. The mean and standard deviation of coefficients in each sub bands can be used as the high frequency features. Experiments show that the proposed algorithm using the integrated WBST outperforms the 3D WT.

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