scholarly journals Study of Rail Squat Characteristics through Analysis of Train Axle Box Acceleration Frequency

2021 ◽  
Vol 11 (15) ◽  
pp. 7022
Author(s):  
Hojin Cho ◽  
Jaehak Park
Keyword(s):  
Surface Defects ◽  
Field Tests ◽  
Wavelet Spectrum ◽  
Measured Data ◽  
Acceleration Measurement ◽  
Field Verification ◽  
Matlab Program ◽  
General Line ◽  
Joint Section ◽  
Prototype Design

In this study, a method for detecting the railway surface defects called “squats” using the ABA (Axle Box Acceleration) measurement of trains was proposed. ABA prototype design, implementation, and field tests were conducted to derive and verify the results. The field test was performed using a proven precision measurement system, and the measured data were signal-processed using a Matlab program. The algorithm used to determine the position of the squats was developed based on wavelet spectrum analysis. This study was verified for a section of a domestic general line and, following field verification for the section, squats was detected with a hit rate of about 88.2%. The main locations where the squats occurred were the rail welds and the joint section, and it was confirmed that in some sections, unsupported sleepers occurred at the locations where the squats occurred.

Wavelet spectrum estimation

Geophysics ◽  
1999 ◽  
Vol 64 (6) ◽  
pp. 1836-1846 ◽  
Author(s):  
Tik Hing Tan
Keyword(s):  
Material Properties ◽  
Pressure Field ◽  
Wavelet Spectrum ◽  
Measured Data ◽  
Complex Spectrum ◽  
Spectrum Estimation ◽  
Wave Propagation Velocity ◽  
Complex Source ◽  
Individual Source ◽  
Source Array

A method for complex source signature estimation for offshore acquisition is presented. Although the wave‐propagation velocity in the water is assumed to be known, no assumptions about the material properties underwater are made. The inputs to the algorithm are the pressure field measured along an end of spread streamer cable, the coordinates of the sources, and the depth of the cable. The output is the complex spectrum of each individual source in the source array. This article discusses the physical interpretation of the equations. It is shown that the estimated wavelets depend on the direct field only. The sensitivities of the method are also discussed. Application of the algorithm on generated and measured data is presented.

Hoist Positioning System Based on the Acceleration Sensor

2013 ◽  
Vol 273 ◽  
pp. 542-546
Author(s):  
Fu Zhong Wang ◽  
Fu Kai Zhang ◽  
Li Min Zhang
Keyword(s):  
Circuit Design ◽  
Measurement Accuracy ◽  
Field Tests ◽  
Signal Interference ◽  
Acceleration Sensor ◽  
Acceleration Measurement ◽  
Acceleration Signal ◽  
Calculation Results ◽  
Composite Filter ◽  
Hardware Circuit

A displacement measurement based on the acceleration sensor, the acceleration signal detection, conditioning hardware circuit design and displacement calculation; Due to signal interference in the measurement process, in order to improve the measurement accuracy of the acceleration signal, a composite filter, and completed the programming of the MSP430 microcontroller, field tests showed that the displacement calculation results obtained on the basis of the acceleration measurement to fully meet the accuracy requirements of field measurement.

scholarly journals Detection and Classification System for Rail Surface Defects Based on Eddy Current

Sensors ◽  
2021 ◽  
Vol 21 (23) ◽  
pp. 7937
Author(s):  
Tiago A. Alvarenga ◽  
Alexandre L. Carvalho ◽  
Leonardo M. Honorio ◽  
Augusto S. Cerqueira ◽  
Luciano M. A. Filho ◽  
...  
Keyword(s):  
Embedded System ◽  
Eddy Current ◽  
Wavelet Transforms ◽  
Surface Defects ◽  
Field Tests ◽  
Network Size ◽  
Automatic Identification ◽  
Railway System ◽  
The Embedded System ◽  
Railway Maintenance

The prospect of growth of a railway system impacts both the network size and its occupation. Due to the overloaded infrastructure, it is necessary to increase reliability by adopting fast maintenance services to reach economic and security conditions. In this context, one major problem is the excessive friction caused by the wheels. This contingency may cause ruptures with severe consequences. While eddy’s current approaches are adequate to detect superficial damages in metal structures, there are still open challenges concerning automatic identification of rail defects. Herein, we propose an embedded system for online detection and location of rails defects based on eddy current. Moreover, we propose a new method to interpret eddy current signals by analyzing their wavelet transforms through a convolutional neural network. With this approach, the embedded system locates and classifies different types of anomalies, enabling an optimization of the railway maintenance plan. Field tests were performed, in which the rail anomalies were grouped in three classes: squids, weld and joints. The results showed a classification efficiency of ~98%, surpassing the most commonly used methods found in the literature.

Lessons from two field tests on pipeline damage detection using acceleration measurement

2011 ◽  
Author(s):  
Masanobu Shinozuka ◽  
Sungchil Lee ◽  
Sehwan Kim ◽  
Pai H. Chou
Keyword(s):  
Damage Detection ◽  
Field Tests ◽  
Acceleration Measurement

Defect and Position Measurement of Pipeline Inner Surface Defects

2013 ◽  
Vol 552 ◽  
pp. 475-478
Author(s):  
Su Ping Bai ◽  
Hai Yang Jiang ◽  
Zhong Yao Zhu
Keyword(s):  
Large Scale ◽  
Surface Defects ◽  
Measured Data ◽  
Step Motor ◽  
Position Measurement ◽  
Gear Drive ◽  
Inner Surface ◽  
Exact Position ◽  
On Line

The paper aims to measure the exact position while detecting inner surface defects of large scale pipeline. A realizable method using opto-electrical is presented in this paper, which can give the position of opto-electrical sensor. On-line measured data is automatically recorded and processed with precision because of the application of step motor and gear drive, as well as software controlling computer.

Defects in Crystals

1968 ◽  
Vol 26 ◽  
pp. 244-245
Author(s):  
Kenneth R. Lawless
Keyword(s):  
Electron Microscope ◽  
Point Defects ◽  
Surface Defects ◽  
Chemical Properties ◽  
Material Point ◽  
Crystal Defects ◽  
Defects In Crystals ◽  
Irradiation Effects ◽  
Normal Lattice ◽  
Line Defects

One of the most important applications of the electron microscope in recent years has been to the observation of defects in crystals. Replica techniques have been widely utilized for many years for the observation of surface defects, but more recently the most striking use of the electron microscope has been for the direct observation of internal defects in crystals, utilizing the transmission of electrons through thin samples.Defects in crystals may be classified basically as point defects, line defects, and planar defects, all of which play an important role in determining the physical or chemical properties of a material. Point defects are of two types, either vacancies where individual atoms are missing from lattice sites, or interstitials where an atom is situated in between normal lattice sites. The so-called point defects most commonly observed are actually aggregates of either vacancies or interstitials. Details of crystal defects of this type are considered in the special session on “Irradiation Effects in Materials” and will not be considered in detail in this session.

Characterization of homoepitaxial diamond films by Electron microscopy

1991 ◽  
Vol 49 ◽  
pp. 880-881
Author(s):  
D.P. Malta ◽  
S.A. Willard ◽  
R.A. Rudder ◽  
G.C. Hudson ◽  
J.B. Posthill ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Surface Defects ◽  
Substrate Surface ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Polycrystalline Diamond ◽  
Large Degree ◽  
Rf Plasma ◽  
Semiconducting Diamond

Semiconducting diamond films have the potential for use as a material in which to build active electronic devices capable of operating at high temperatures or in high radiation environments. A major goal of current device-related diamond research is to achieve a high quality epitaxial film on an inexpensive, readily available, non-native substrate. One step in the process of achieving this goal is understanding the nucleation and growth processes of diamond films on diamond substrates. Electron microscopy has already proven invaluable for assessing polycrystalline diamond films grown on nonnative surfaces.The quality of the grown diamond film depends on several factors, one of which is the quality of the diamond substrate. Substrates commercially available today have often been found to have scratched surfaces resulting from the polishing process (Fig. 1a). Electron beam-induced current (EBIC) imaging shows that electrically active sub-surface defects can be present to a large degree (Fig. 1c). Growth of homoepitaxial diamond films by rf plasma-enhanced chemical vapor deposition (PECVD) has been found to planarize the scratched substrate surface (Fig. 1b).

Microstructure of sputter deposited Ni-Sb ohmic contacts on GaAs

1989 ◽  
Vol 47 ◽  
pp. 450-451
Author(s):  
S. Yegnasubramanian ◽  
V.C. Kannan ◽  
R. Dutto ◽  
P.J. Sakach
Keyword(s):  
High Performance ◽  
Ohmic Contacts ◽  
Surface Defects ◽  
Pure Metal ◽  
Device Fabrication ◽  
Native Oxide ◽  
Metal Thin Films ◽  
Recent Developments ◽  
Different Temperatures ◽  
Sputter Deposited

Recent developments in the fabrication of high performance GaAs devices impose crucial requirements of low resistance ohmic contacts with excellent contact properties such as, thermal stability, contact resistivity, contact depth, Schottky barrier height etc. The nature of the interface plays an important role in the stability of the contacts due to problems associated with interdiffusion and compound formation at the interface during device fabrication. Contacts of pure metal thin films on GaAs are not desirable due to the presence of the native oxide and surface defects at the interface. Nickel has been used as a contact metal on GaAs and has been found to be reactive at low temperatures. Formation Of Ni2 GaAs at 200 - 350C is reported and is found to grow epitaxially on (001) and on (111) GaAs, but is shown to be unstable at 450C. This paper reports the investigations carried out to understand the microstructure, nature of the interface and composition of sputter deposited and annealed (at different temperatures) Ni-Sb ohmic contacts on GaAs by TEM. Attempts were made to correlate the electrical properties of the films such as the sheet resistance and contact resistance, with the microstructure. The observations are corroborated by Scanning Auger Microprobe (SAM) investigations.

Contrasts of planar defects in reflection electron microscopy

1993 ◽  
Vol 51 ◽  
pp. 1004-1005
Author(s):  
Feng Tsai ◽  
J. M. Cowley
Keyword(s):  
Electron Microscopy ◽  
Surface Defects ◽  
Practical Importance ◽  
Theoretical Treatment ◽  
Crystal Surfaces ◽  
Planar Defects ◽  
Surface Steps ◽  
Surface Reconstructions ◽  
Domain Boundaries ◽  
Reflection Electron Microscopy

Reflection electron microscopy (REM) has been used to study surface defects such as surface steps, dislocations emerging on crystal surfaces, and surface reconstructions. However, only a few REM studies have been reported about the planar defects emerging on surfaces. The interaction of planar defects with surfaces may be of considerable practical importance but so far there seems to be only one relatively simple theoretical treatment of the REM contrast and very little experimental evidence to support its predications. Recently, intersections of both 90° and 180° ferroelectric domain boundaries with BaTiO3 crystal surfaces have been investigated by Tsai and Cowley with REM.The REM observations of several planar defects, such as stacking faults and domain boundaries have been continued by the present authors. All REM observations are performed on a JEM-2000FX transmission electron microscope. The sample preparations may be seen somewhere else. In REM, the incident electron beam strikes the surface of a crystal with a small glancing angle.

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