scholarly journals Experimental study on ground vibration attenuation induced by heavy freight wagons on a railway viaduct

2018 ◽  
Vol 37 (4) ◽  
pp. 881-895 ◽  
Author(s):  
Jingjing Hu ◽  
Yi Luo ◽  
Zaitian Ke ◽  
Penghui Liu ◽  
Jiayun Xu
Keyword(s):  
Ground Vibration ◽  
Dominant Frequency ◽  
Vertical Vibration ◽  
Correlation Factor ◽  
Frequency Bands ◽  
Vibration Effect ◽  
Significant Difference ◽  
Normal Speed ◽  
Train Speed ◽  
Freight Wagons

Studies on ground vibration induced by railway operation usually focused on wagons running on ground or abutments, while vibration from a railway viaduct is often assumed to be much lower. Based on field test in the vicinity of a heavy freight railway viaduct above Shenshan Village, China, the attenuation of ground vibration induced by heavy freight wagons for coal transportation is studied. And evaluation is conducted on an adjacent house to access vibration disturbance to residents near a viaduct. Propagation and attenuation of vibration induced from viaduct are studied by analyzing peak particle velocity and spectra of ground and house vibration in the vicinity of the viaduct. Vibration signals were collected for 34 trains with different train speed and wagon weight. In all monitored situations, vertical vibration is generally larger than horizontal vibration. The relationship between distance to pier and PPV is revealed by a power function modified from Sadovskii formula with high correlation factor. Analysis also indicates a much lower dominant frequency induced by low-speed trains with or without acceleration than normal speed trains. A dramatic amplitude reduction is shown within frequency between 25 Hz and 35 Hz when train speed is reduced. Empty wagons also show smaller amplitude in most frequency bands, with significant difference in 15–25 Hz. Analysis on the house also shows larger vibration in vertical than horizontal, and vibration amplitude in some frequency bands has exceeded relative criteria. Analysis result shows significant ground and house vibration effect form a viaduct, and piers should be considered as vibration sources for ground and houses in future studies.

Experimental modeling of adjacent parallel shield tunnels subjected to train-induced vibration loads

2021 ◽  
pp. 095440972098626
Author(s):  
Junchen Zhang ◽  
Qixiang Yan ◽  
Kai Yang ◽  
Minghui Sun
Keyword(s):  
Experimental Studies ◽  
Bimodal Distribution ◽  
Dominant Frequency ◽  
Experimental Modeling ◽  
Load Curve ◽  
Hilbert Huang Transform ◽  
Frequency Peak ◽  
Train Speed ◽  
Vibration Loads ◽  
Train Induced Vibration

Previous studies have performed numerical simulations of adjacent parallel shield tunnels under train-induced vibration loads. However, few experimental studies have been performed for the interaction mechanisms. In this study, experimental modeling is conduced to explore the interaction of adjacent parallel shield tunnels subjected to different train-induced vibration loads. A new Hilbert-Huang transform (HHT) is applied to obtain the instantaneous responses of tunnels. The results show that the acceleration of the tunnel follows the trend of the train load curve. The peak accelerations of the tunnels experience a unimodal distribution along the train speed, while the dominant frequencies of the tunnels follow a bimodal distribution. The interaction between the adjacent parallel tunnels is significant. The transform of the vibration loads to the adjacent tunnel is through the soil below the tunnel. The farther away from the train load is, the greater the train speed corresponding to the dominant frequency peak.

scholarly journals Clinical Outcomes of Computational Virtual Mapping-Guided Catheter Ablation in Patients With Persistent Atrial Fibrillation: A Multicenter Prospective Randomized Clinical Trial

2021 ◽  
Vol 8 ◽  
Author(s):  
Yong-Soo Baek ◽  
Oh-Seok Kwon ◽  
Byounghyun Lim ◽  
Song-Yi Yang ◽  
Je-Wook Park ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Clinical Trial ◽  
Catheter Ablation ◽  
Computational Modeling ◽  
Controlled Trial ◽  
Dominant Frequency ◽  
Complication Rates ◽  
Clinical Recurrence ◽  
Significant Difference

Background: Clinical recurrence after atrial fibrillation catheter ablation (AFCA) still remains high in patients with persistent AF (PeAF). We investigated whether an extra-pulmonary vein (PV) ablation targeting the dominant frequency (DF) extracted from electroanatomical map–integrated AF computational modeling improves the AFCA rhythm outcome in patients with PeAF.Methods: In this open-label, randomized, multi-center, controlled trial, 170 patients with PeAF were randomized at a 1:1 ratio to the computational modeling-guided virtual DF (V-DF) ablation and empirical PV isolation (E-PVI) groups. We generated a virtual dominant frequency (DF) map based on the atrial substrate map obtained during the clinical AF ablation procedure using computational modeling. This simulation was possible within the time of the PVI procedure. V-DF group underwent extra-PV V-DF ablation in addition to PVI, but DF information was not notified to the operators from the core lab in the E-PVI group.Results: After a mean follow-up period of 16.3 ± 5.3 months, the clinical recurrence rate was significantly lower in the V-DF than with E-PVI group (P = 0.018, log-rank). Recurrences appearing as atrial tachycardias (P = 0.145) and the cardioversion rates (P = 0.362) did not significantly differ between the groups. At the final follow-up, sinus rhythm was maintained without any AADs in 74.7% in the V-DF group and 48.2% in the E-PVI group (P < 0.001). No significant difference was found in the major complication rates (P = 0.489) or total procedure time (P = 0.513) between the groups. The V-DF ablation was independently associated with a reduced AF recurrence after AFCA [hazard ratio: 0.51 (95% confidence interval: 0.30–0.88); P = 0.016].Conclusions: The computational modeling-guided V-DF ablation improved the rhythm outcome of AFCA in patients with PeAF.Clinical Trial Registration: Clinical Research Information Service, CRIS identifier: KCT0003613.

scholarly journals Evaluation of the Diagnostic Advantage of Intraoral D and E Film for Detecting Interproximal Caries

2004 ◽  
Vol 5 (4) ◽  
pp. 58-70 ◽  
Author(s):  
Abdolrahim Davari ◽  
Fatemeh Ezoddini Ardakani ◽  
Daryoush Goodarzipour ◽  
Koorosh Goodarzipour
Keyword(s):  
High Speed ◽  
The Body ◽  
Diagnostic Image ◽  
Proximal Caries ◽  
Diagnostic Quality ◽  
Type D ◽  
Film Type ◽  
Significant Difference ◽  
Normal Speed ◽  
A Minor

Abstract Clinicians strive to reduce the exposure of patients to X-ray radiation in an effort to decrease its harmful effects on the body. A potential strategy for achieving this goal is the use of high-speed films that require less exposure to radiation to generate a diagnostic image. There are two film types commonly used in intraoral radiography: high speed or “Ekta-speed” film (Type E) and normal speed or Ultra-speed film (Type D). Type E film requires nearly half of the exposure time that is required by Type D films to produce an acceptable diagnostic image; however, the diagnosis quality and usability of these film types are under question. The purpose of this research is to compare the diagnostic quality of Type E with Type D film when used to diagnose proximal caries. In this study 40 pairs of extracted maxillary premolar teeth were chosen and divided into four groups of 10 pairs. Cavities were made on proximal surfaces at different depths (0.5, 1, 1.5, and 2 mm) for each group. Bitewing radiographs were then taken on each pair of teeth using Type E film and then again using Type D film. Radiographs were evaluated by two oral radiologists and two operative dentistry specialists who recorded the perceived diagnostic depth of the prepared cavities. Our data showed both Type D and E films are suitable for use in diagnosing proximal caries, and despite a minor discrepancy between them no significant difference was found with regard to their value in diagnosing proximal caries. Citation Ardakani FE, Davari A, Goodarizpour D, et. al. Evaluation of the Diagnostic Advantage of Intraoral D and E Film for Detecting Interproximal Caries. J Contemp Dent Pract 2004 November;(5)4:058-070.

Abstract 4104: Organization of Atrial Signals is Critical Prior to Cardioversion of Atrial Fibrillation with Intravenous Flecainide: Insight from Spectral Analysis of Intracardiac Electrograms

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Jiun Tuan ◽  
Suman Kundu ◽  
Mohamed Jeilan ◽  
Faizel Osman ◽  
Rajkumar Mantravadi ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Spectral Analysis ◽  
Catheter Ablation ◽  
Cycle Length ◽  
Dominant Frequency ◽  
Relative Increase ◽  
Significant Difference ◽  
Before And After ◽  
Atrial Activation ◽  
Relative Change

Introduction & Hypothesis: Studies in catheter ablation of atrial fibrillation (AF) show that an increase in cycle length (CL) and higher organization index (OI) is associated with termination of AF. We hypothesize that similar changes can be seen in chemical cardioversion with Flecainide Methods: Patients who were still in AF at the end of catheter ablation for AF were given intravenous flecainide. OI and dominant frequency (DF) were obtained by Fast Fourier Transform of coronary sinus electrograms over 10s in AF, before and after flecainide infusion. Mean CL was also calculated. Results: 28 patients were identified (18 paroxysmal AF and 10 persistent AF). 8 cardioverted to sinus rhythm (SR) with flecainide. In all patients, mean CL increased from 211 ± 44 ms to 321 ± 85 ms (p <0.001). Mean DF decreased from 5.2 ± 1.03 Hz to 3.6 ± 1.04 Hz (p <0.001). Mean OI was 0.33 ± 0.13 before and 0.32 ± 0.11 after flecainide (p = 0.90). Comparing patients who cardioverted to SR with those who did not, OI post-flecainide was 0.41 ± 0.12 vs 0.29 ± 0.10 (p=0.013) and relative change in OI was 29 ± 33% vs −3.9 ± 27% (p=0.016) respectively. No significant difference was noted in the change in CL and DF in the 2 groups. Logistic regression showed that a greater relative increase in OI (p=0.04), a higher OI post-flecainide (p=0.03) and SR at start of procedure (p=0.03) are independently associated with cardioversion to SR with flecainide. Conclusion: Increase in OI, independent of changes to the CL and DF, appears critical to AF termination with flecainide. The increase in OI may reflect an increase in size and reduction in the number of re-entrant circuits, which together with slowing of atrial activation, result in return to SR.

Effects of meal volume and composition on gastric myoelectrical activity

1998 ◽  
Vol 274 (2) ◽  
pp. G430-G434 ◽  
Author(s):  
Daniela Levanon ◽  
Ming Zhang ◽  
William C. Orr ◽  
J. D. Z. Chen
Keyword(s):  
Dominant Frequency ◽  
Gastric Myoelectrical Activity ◽  
Myoelectrical Activity ◽  
Standard Meal ◽  
High Fiber ◽  
Gastric Slow Waves ◽  
Food Properties ◽  
Postprandial Motility ◽  
Significant Difference ◽  
Effect Of Food

The absence of a standard meal in electrogastrography may limit its clinical significance. Different meals may fail to produce the expected postprandial motility pattern. The aim of this study was to investigate the effect of meal volume and composition on postprandial myoelectrical activity. Fourteen healthy subjects were given four meals that differed from a “reference meal” in one single parameter (volume, calorie, or fiber content). Gastric myoelectrical activity was measured using surface electrogastrography. Spectral and statistical analyses were performed to investigate the effect of food properties on electrogastrogram (EGG) parameters. It was found that the reference meal produced a postprandial increase in the dominant frequency ( P < 0.007), dominant power ( P < 0.04), and percentage of normal 2–4 cycle/min gastric slow waves ( P > 0.05). Similar changes were observed with the low-volume and high-fiber meals but not with the reduced-calorie meal. Fasting EGG parameters in all four sessions showed no significant difference. It was concluded that low-calorie meals do not result in expected postprandial physiological responses and thus are not appropriate for EGG tests. A volume reduction of down to one-half the volume of a regular meal does not affect postprandial changes of the EGG; thus a condensed test meal may be recommended for symptomatic patients.

scholarly journals An Experimental Investigation of Moisture-Induced Softening Mechanism of Marble Based on Quantitative Analysis of Acoustic Emission Waveforms

2019 ◽  
Vol 9 (3) ◽  
pp. 446
Author(s):  
Huang Yiming ◽  
Deng Jianhui ◽  
Zhu Jun
Keyword(s):  
Acoustic Emission ◽  
Dominant Frequency ◽  
Uniaxial Compression Test ◽  
Test Results ◽  
Frequency Bands ◽  
Softening Mechanism ◽  
Final Failure ◽  
Shear Failures ◽  
Microcosmic Mechanism ◽  
Ae Signals

The decrease of strength after saturation of rocks is known as moisture-induced softening. To date, there are numerous studies on the mechanism of moisture-induced softening of different rocks. However, due to a lack of effective observational methods, the microcosmic mechanism of moisture-induced softening still needs to be understood. We collected and processed acoustic emission (AE) signals during the uniaxial compression test of marble specimens. The results of spectral and statistical analysis show that two dominant frequency bands of AE waveforms exist regardless of the specimen’s water content. Additionally, for the AE signals from the saturated specimens, the ranges of the low and high frequency bands are wider than dried rock samples. Besides, since the tensile and shear failures in the rock release low and high dominant frequency AE signals, respectively, the test results of this paper show that micro-shear and micro-tensile failures dominate the final failure of dried and saturated rocks, respectively.

scholarly journals Kolmogorov Complexity of Coronary Sinus Atrial Electrograms before Ablation Predicts Termination of Atrial Fibrillation after Pulmonary Vein Isolation

Entropy ◽  
2019 ◽  
Vol 21 (10) ◽  
pp. 970 ◽  
Author(s):  
Stępień ◽  
Kuklik ◽  
Żebrowski ◽  
Sanders ◽  
Derejko ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Catheter Ablation ◽  
Pulmonary Vein ◽  
Pulmonary Vein Isolation ◽  
Coronary Sinus ◽  
Kolmogorov Complexity ◽  
Similarity Index ◽  
Dominant Frequency ◽  
Significant Difference ◽  
The Rich

Atrial fibrillation (AF) is related to a very complex local electrical activity reflected in the rich morphology of intracardiac electrograms. The link between electrogram complexity and efficacy of the catheter ablation is unclear. We test the hypothesis that the Kolmogorov complexity of a single atrial bipolar electrogram recorded during AF within the coronary sinus (CS) at the beginning of the catheter ablation may predict AF termination directly after pulmonary vein isolation (PVI). The study population consisted of 26 patients for whom 30 s baseline electrograms were recorded. In all cases PVI was performed. If AF persisted after PVI, ablation was extended beyond PVs. Kolmogorov complexity estimated by Lempel–Ziv complexity and the block decomposition method was calculated and compared with other measures: Shannon entropy, AF cycle length, dominant frequency, regularity, organization index, electrogram fractionation, sample entropy and wave morphology similarity index. A 5 s window length was chosen as optimal in calculations. There was a significant difference in Kolmogorov complexity between patients with AF termination directly after PVI compared to patients undergoing additional ablation (p < 0.01). No such difference was seen for remaining complexity parameters. Kolmogorov complexity of CS electrograms measured at baseline before PVI can predict self-termination of AF directly after PVI.

Prediction of shear strain induced by blasting waves in surface structures based on coupled frequency, velocity, and displacement effects

2020 ◽  
pp. 107754632093525
Author(s):  
Reza Nateghi ◽  
Kamran Goshtasbi ◽  
Hamid Reza Nejati
Keyword(s):  
Response Spectrum ◽  
Simple Procedure ◽  
Structural Response ◽  
Ground Vibration ◽  
Horizontal Displacement ◽  
Dominant Frequency ◽  
Rock Formations ◽  
Frequency Peak ◽  
Geological Conditions ◽  
Relative Stress

Blasting ground vibration is an undesirable side effect of using explosives to fragment rocks. There is not any universally accepted standard to determine limitations of blast vibrations; however, velocity is the most commonly used method to measure ground vibrations. Because the structural response is highly frequency dependent, the frequency content is an essential characteristic of blast-induced shock waves along with the velocity. The magnitude of blast-induced displacement or velocity and their relative stress and strain are directly related to the quantity of charge, distance from blasting point, and geological conditions. These effects were not considered in the response spectrum theory of structures. This article tries to propose a new procedure to predict the shear displacement and relative strain for optimization of blasting patterns before the explosion. It can be accomplished by representing the effects of both velocity and frequency on the horizontal displacement of the structures based on measurements undertaken by the authors in two different rock formations. In this study, collected data were analyzed statistically to determine the coupled effects of dominant frequency, peak particle velocity, and peak particle displacement to propose a simple procedure for predicting the range of blast-induced displacement and related strain in structures.

In Situ Testing of the Vibration Isolation Effect of the Vibration Isolating Trench

2011 ◽  
Vol 90-93 ◽  
pp. 1679-1683 ◽  
Author(s):  
Kun Ming Mao ◽  
Guo Xing Chen ◽  
Yang Zhang ◽  
Xiao Xing Hong ◽  
Bin Ruan
Keyword(s):  
Vibration Isolation ◽  
Ground Surface ◽  
Ground Vibration ◽  
Isolation Effect ◽  
Good Effect ◽  
Vibration Velocity ◽  
Surface Vibration ◽  
Intercity Railway ◽  
Train Speed ◽  
Filtering Effect

One trench for agricultural irrigation next to the Hu-Ning Intercity Railway viaduct section were tested and analyzed in order to obtain the effect of ground vibration isolation when CRH trains run on. The result shows that with the decreasing train speed, the peak value of ground vibration velocity decreases and the main frequency of ground vibration heightens. Trench has lowpass filtering effect on ground surface vibration. The slower the train speed, the better the effect of isolation, but the phenomenon that ground surface vibration increases before trench is more obvious. When the length of trench is much longer than the length of train, the number of carriages has little effect on vibration isolation effect of the trench. When railways are built, consulting with nearby residents and department of agriculture, and the trench’s length, depth, breadth and the distance to railway should be designed reasonably. And then the trench in addition to meet need of irrigation, but also has very good effect on vibration isolation.

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