scholarly journals A Train-Mounted GPR System for Operating Railway Tunnel Inspection

2020 ◽  
Author(s):  
Hongqiang Xiong ◽  
Guofeng Su ◽  
Chunliu Zhang ◽  
Baoqing Li ◽  
Wentao Wei
Keyword(s):  
Time Window ◽  
Center Frequency ◽  
Maximum Speed ◽  
Railway Tunnel ◽  
Detection Depth ◽  
Tunnel Inspection ◽  
Important Means ◽  
Shared Time ◽  
Railway Passenger ◽  
Ground Penetrating

With the increasing number and aging of railway tunnels, regular inspection will be an important means to ensure the safety for operation railways. A train-mounted ground penetrating radar system with cores of air-coupled antennas and shared time-window model has been developed to allow for long-distance and fast inspection of tunnels. The system consists of 6 groups of air-coupled antennas with center frequency of 300 MHz. The distance between antenna and lining is 0.5–4.0 m, the scanning rate of the system is 976 scans/Sec and the detection depth of the GPR can reach to 2.5 m. Under the theoretical design, the maximum speed of train can reach 70.27 km/h with a scan interval of 0.02 m. The test results on Shenyang-Dandong railway passenger dedicated line show that the system can identify the thickness of lining, the void and the backfill state behind lining.

Adaptive Multiple Second-order Synchrosqueezing Wavelet Transform and Its Application in Wind Turbine Gearbox Fault Diagnosis

2021 ◽  
Author(s):  
Zhaohong Yu ◽  
Cancan Yi ◽  
Xiangjun Chen ◽  
Tao Huang
Keyword(s):  
Wavelet Transform ◽  
Wind Turbine ◽  
Time Window ◽  
Vibration Signal ◽  
Second Order ◽  
Center Frequency ◽  
Wind Turbine Gearbox ◽  
Adaptive Wavelet ◽  
Time Frequency ◽  
Window Width

Abstract Wind turbines usually operate in harsh environments and in working conditions of variable speed, which easily causes their key components such as gearboxes to fail. The gearbox vibration signal of a wind turbine has nonstationary characteristics, and the existing Time-Frequency (TF) Analysis (TFA) methods have some problems such as insufficient concentration of TF energy. In order to obtain a more apparent and more congregated Time-Frequency Representation (TFR), this paper proposes a new TFA method, namely Adaptive Multiple Second-order Synchrosqueezing Wavelet Transform (AMWSST2). Firstly, a short-time window is innovatively introduced on the foundation of classical Continuous Wavelet Transform (CWT), and the window width is adaptively optimized by using the center frequency and scale factor. After that, a smoothing process is carried out between different segments to eliminate the discontinuity and thus Adaptive Wavelet Transform (AWT) is generated. Then, on the basis of the theoretical framework of Synchrosqueezing Transform (SST) and accurate Instantaneous Frequency (IF) estimation by the utilization of second-order local demodulation operator, Adaptive Second-order Synchrosqueezing Wavelet Transform (AWSST2) is formed. Considering that the quality of actual time-frequency analysis is greatly disturbed by noise components, through performing multiple Synchrosqueezing operations, the congregation of TFR energy is further improved, and finally, the AMWSST2 algorithm studied in this paper is proposed. Since Synchrosqueezing operations are performed only in the frequency direction, this method AMWSST2 allows the signal to be perfectly reconstructed. For the verification of its effectiveness, this paper applies it to the processing of the vibration signal of the gearbox of a 750 kW wind turbine.

The Application of Ground Penetrating Radar in Railway Tunnel Concrete Quality Detection

2011 ◽  
Vol 228-229 ◽  
pp. 1185-1189
Author(s):  
Su Qi ◽  
Xing Xing Chen
Keyword(s):  
Ground Penetrating Radar ◽  
Traditional Method ◽  
Detection Methods ◽  
Railway Tunnel ◽  
Testing Method ◽  
Quality Detection ◽  
Quality Testing ◽  
Concrete Quality ◽  
Ground Penetrating ◽  
Drilling Core

The priority of traditional tunnel concrete quality testing method is drilling core .The traditional method damage tunnel structure and detection speed is slowly.we use this method cann’t effectively meet the demand of rapid growth of tunnel concrete qulity testing. So the more fast and effective detection methods are needed.A new fast and effective kind of concrete quality detection methods is ground penetrating radar can meet the extensive tunnel concrete nondestructive testing. This paper introduces the basic principle of ground penetrating radar.I illustrate the application of railway tunnel testing by the testing in Ju Gan runnel of Lan Yue railway.TI is significance for railway tunnel concrete in future.

scholarly journals Radar Imager for Mars’ Subsurface Experiment—RIMFAX

2020 ◽  
Vol 216 (8) ◽  
Author(s):  
Svein-Erik Hamran ◽  
David A. Paige ◽  
Hans E. F. Amundsen ◽  
Tor Berger ◽  
Sverre Brovoll ◽  
...  
Keyword(s):  
Continuous Wave ◽  
Sand Dunes ◽  
Landing Site ◽  
Wide Band ◽  
Center Frequency ◽  
Depth Range ◽  
Fmcw Radar ◽  
Shallow Subsurface ◽  
Eventual Return ◽  
Ground Penetrating

AbstractThe Radar Imager for Mars’ Subsurface Experiment (RIMFAX) is a Ground Penetrating Radar on the Mars 2020 mission’s Perseverance rover, which is planned to land near a deltaic landform in Jezero crater. RIMFAX will add a new dimension to rover investigations of Mars by providing the capability to image the shallow subsurface beneath the rover. The principal goals of the RIMFAX investigation are to image subsurface structure, and to provide information regarding subsurface composition. Data provided by RIMFAX will aid Perseverance’s mission to explore the ancient habitability of its field area and to select a set of promising geologic samples for analysis, caching, and eventual return to Earth. RIMFAX is a Frequency Modulated Continuous Wave (FMCW) radar, which transmits a signal swept through a range of frequencies, rather than a single wide-band pulse. The operating frequency range of 150–1200 MHz covers the typical frequencies of GPR used in geology. In general, the full bandwidth (with effective center frequency of 675 MHz) will be used for shallow imaging down to several meters, and a reduced bandwidth of the lower frequencies (center frequency 375 MHz) will be used for imaging deeper structures. The majority of data will be collected at regular distance intervals whenever the rover is driving, in each of the deep, shallow, and surface modes. Stationary measurements with extended integration times will improve depth range and SNR at select locations. The RIMFAX instrument consists of an electronic unit housed inside the rover body and an antenna mounted externally at the rear of the rover. Several instrument prototypes have been field tested in different geological settings, including glaciers, permafrost sediments, bioherme mound structures in limestone, and sedimentary features in sand dunes. Numerical modelling has provided a first assessment of RIMFAX’s imaging potential using parameters simulated for the Jezero crater landing site.

Application of the Ground Penetrating Radar in the Quality Detection of Tunnel Lining

2011 ◽  
Vol 243-249 ◽  
pp. 5381-5385 ◽  
Author(s):  
Ji Shun Pan ◽  
Lei Yang ◽  
Yuan Bao Leng ◽  
Zhi Quan Lv
Keyword(s):  
Data Processing ◽  
Ground Penetrating Radar ◽  
Tunnel Lining ◽  
Quality Detection ◽  
Steel Bar ◽  
Data Processing Method ◽  
Work Mechanism ◽  
Important Means ◽  
Working Principle ◽  
Ground Penetrating

Based on the ground penetrating radar's work mechanism, this article briefly introduces the working principle and the data processing method of ground penetrating radar detecting the tunnel lining. In view of the lining quality detection's characteristics, it summarizes a series of atlas reflection characteristic of the examination target such as the lining thickness, the backfill quality, the steel bar reinforcement situation, the adjacent formation structural feature and so on, and analyses and comments on them with project examples. The research believes that under appropriate working condition, as an important means to guarantee the construction security and maintain the tunnel health, ground penetrating radar technology can examine the lining quality fast and effectively, and meet the needs of the tunnel lining quality detection with suitable equipment, working method and data processing plan.

Dynamic Scheduling Model and Algorithm for Dispatching Trains in High-Speed Railway Passenger Station

2010 ◽  
Author(s):  
Yixiang Yue ◽  
Leishan Zhou
Keyword(s):  
High Speed ◽  
Large Scale ◽  
Job Shop ◽  
Dynamic Scheduling ◽  
Time Window ◽  
Real Life ◽  
Greedy Heuristic ◽  
Railway Station ◽  
High Speed Railway ◽  
Railway Passenger

Regarding the railway station tracks and train running routes as machines, all trains in this railway station as jobs, dispatching trains in high-speed railway passenger stations can be considered as a special type of Job-Shop Problem (JSP). In this paper, we proposed a multi-machines, multi-jobs JSP model with special constraints for Operation Plan Scheduling Problem (OPSP) in high-speed railway passenger stations, and presented a fast heuristic algorithm based on greedy heuristic. This algorithm first divided all operations into several layers according to the yards attributes and the operation’s urgency level. Then every operation was allotted a feasible time window, each operation was assigned to a specified “machine” sequenced or backward sequenced within the time slot, layer by layer according to its priority. As we recorded and modified the time slots dynamically, the searching space was decreased dramatically. And we take the South Beijing High-speed Railway Station as example and give extensive numerical experiment. Computational results based on real-life instance show that the algorithm has significant merits for large scale problems; can both reduce tardiness and shorten cycle times. The empirical evidence also proved that this algorithm is industrial practicable.

scholarly journals A compact lightweight multipurpose ground-penetrating radar for glaciological applications

2011 ◽  
Vol 57 (206) ◽  
pp. 1113-1118 ◽  
Author(s):  
E.V. Vasilenko ◽  
F. Machío ◽  
J.J. Lapazaran ◽  
F.J. Navarro ◽  
K. Frolovskiy
Keyword(s):  
Dynamic Range ◽  
Time Window ◽  
Signal To Noise Ratio ◽  
High Signal ◽  
Peak Voltage ◽  
Recording Time ◽  
Single Person ◽  
Radio Echo Sounding ◽  
Power Peak ◽  
Ground Penetrating

AbstractWe describe a compact lightweight impulse radar for radio-echo sounding of subsurface structures designed specifically for glaciological applications. The radar operates at frequencies between 10 and 75 MHz. Its main advantages are that it has a high signal-to-noise ratio and a corresponding wide dynamic range of 132 dB due mainly to its ability to perform real-time stacking (up to 4096 traces) as well as to the high transmitted power (peak voltage 2800 V). The maximum recording time window, 40 μs at 100 MHz sampling frequency, results in possible radar returns from as deep as 3300 m. It is a versatile radar, suitable for different geophysical measurements (common-offset profiling, common midpoint, transillumination, etc.) and for different profiling set-ups, such as a snowmobile and sledge convoy or carried in a backpack and operated by a single person. Its low power consumption (6.6 W for the transmitter and 7.5 W for the receiver) allows the system to operate under battery power for >7 hours with a total weight of <9 kg for all equipment, antennas and batteries.

Simulation Test of Equipment of Non-Contact Detection with GPR

2011 ◽  
Vol 317-319 ◽  
pp. 2416-2420
Author(s):  
Yan Qing Yang ◽  
Shao Hui He ◽  
Bo Jiang ◽  
Fa Lin Qi
Keyword(s):  
Work Conditions ◽  
Contact Detection ◽  
Simulation Test ◽  
Railway Tunnel ◽  
Detection Distance ◽  
Main Technique ◽  
Simple Detection ◽  
Set Up ◽  
Composite Lining ◽  
Ground Penetrating

The composite lining model of railway tunnel is set up and then simulation test is presented by non-contact detection with the simple detection equipment of ground penetrating radar (GPR) to study the main technique parameters of the equipment. The results show that the lining can be detected by the way, and the quality of GPR scan obtained in the simulation test decreases with the detection distance increasing. In the GPR scan obtained when keeping ground-coupled shielding antenna of 400MHz 20cm away from the ground(the distant from the bottom of GPR antenna to the surface of lining specimen), a variety of work conditions that has been preset in the experimental design can be identified, moreover, the location and range of both uncompacted backfill and cavity behind the lining etc. approach those that can be get when the antenna sticking to the lining, thus providing satisfactory qualitative interpretation of GPR scan. In addition, the deviation range of GPR non-contact detection is close to that when the antenna sticking to the lining, thus ensuring the detection value accuracy of lining thickness.

Detection of voids behind segments in the shield tunnels by using Ground Penetrating Radar

2021 ◽  
Author(s):  
Hai Liu ◽  
JianYing Lin ◽  
Xu Meng ◽  
Yanliang Du
Keyword(s):  
Remote Sensing ◽  
Field Experiment ◽  
Ground Penetrating Radar ◽  
Center Frequency ◽  
Concrete Lining ◽  
Shield Tunnel ◽  
Reverse Time ◽  
Reverse Time Migration ◽  
Time Migration ◽  
Ground Penetrating

&lt;p&gt;&lt;em&gt;Abstract&amp;#8212;&lt;/em&gt;Metro traffic in subsurface tunnels is under a rapid development in many cities in the recent decades. However, the voids and other concealed defects inside and/or behind the tunnel lining pose critical threat to the safety of the operating metro tunnels. Ground penetrating radar (GPR) is a non-destructive geophysical technique by transmitting electromagnetic (EM) waves and receiving the reflected signals. GPR has proved its capability in the detection of the existence of tunnel structural defects and anomalies. However, the voids are still hard to be recognized in a GPR image due to the strong scattering clutter caused by the dense steel bars reinforced inside the concrete lining [1]. In this paper, we analyze the propagations of EM waves through reinforce concrete segments of shield tunnels by finite difference time domain (FDTD) simulations and model test. &amp;#160;Firstly, a series of simulations results we have done, indicates that the center frequency of GPR ranges from 400 MHz to 600 MHz has a good penetration through the densely reinforced concrete lining. And the distance between the antennas and the surface of shield tunnel segments should be less than 0.2 m to ensure a good coupling of incident electromagnetic energy into the concrete structure. Then, to image the geometric features of the void behind the segment, reverse-time migration method is applied to the simulated GPR B-scan profile, which presents higher resolution results than the results by using the traditional diffraction stack migration (Figure 1) [2]. Finally, the field experiment results prove that a commercial GPR system operating at a center frequency of 600 MHz do detect a void behind the shield tunnel (Figure 2). The reflection from the void, which starts from the back interface of the segments and lasts over 20 ns, are significantly different from the reflections from the rebars (Figure 3). In summary, GPR has potential in the detection of voids behind the shield tunnel segment. More simulations and field experiments will be performed in the future.&lt;/p&gt;&lt;p&gt;Keywords&amp;#8212;ground penetrating radar (GPR); shield tunnel; voids; reverse time migration (RTM)&lt;/p&gt;&lt;p&gt;Acknowledgement&amp;#8212;this work was supported by Shenzhen Science and Technology program (grant number:KQTD20180412181337494).&lt;/p&gt;&lt;p&gt;&lt;img src=&quot;https://contentmanager.copernicus.org/fileStorageProxy.php?f=gnp.5ecbddc6f70069664311161/sdaolpUECMynit/12UGE&amp;app=m&amp;a=0&amp;c=eb6a5ae55b4b24b5585021db0e5ca760&amp;ct=x&amp;pn=gnp.elif&amp;d=1&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&lt;p&gt;Fig. 1 Numerical simulation of two segments of 2D shield tunnel. (a) numerical model, (b) simulated GPR B-scan profile, (c) migrated profile by using diffraction stack migration and (d) migrated profile by using reverse-time migration.&lt;/p&gt;&lt;p&gt;&lt;img src=&quot;https://contentmanager.copernicus.org/fileStorageProxy.php?f=gnp.659ecbe6f70069964311161/sdaolpUECMynit/12UGE&amp;app=m&amp;a=0&amp;c=07531c033a4f74c3a8e3ac1f5f47316c&amp;ct=x&amp;pn=gnp.elif&amp;d=1&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&lt;p&gt;Fig. 2 One photo of the field experiment.&lt;/p&gt;&lt;p&gt;&lt;img src=&quot;https://contentmanager.copernicus.org/fileStorageProxy.php?f=gnp.d7c12807f70068274311161/sdaolpUECMynit/12UGE&amp;app=m&amp;a=0&amp;c=dd5c073fd4c06a9fd77db502c1d017f2&amp;ct=x&amp;pn=gnp.elif&amp;d=1&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&lt;p&gt;Fig. 3 GPR reflections from a void behind the segment of a subway tunnel&lt;/p&gt;&lt;p&gt;References&lt;/p&gt;&lt;p&gt;[1]&amp;#160;&amp;#160;&amp;#160;&amp;#160; H. Liu, H. Lu, J. Lin, F. Han, C. Liu, J. Cui, B. F. Spencer, &amp;#8220;Penetration Properties of Ground Penetrating Radar Waves through Rebar Grids&amp;#8221; , IEEE Geoscience and Remote Sensing Letters ( &lt;strong&gt;DOI:&lt;/strong&gt; 10.1109/LGRS.2020.2995670)&lt;/p&gt;&lt;p&gt;[2]&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160; H. Liu, Z. Long, F. Han, G. Fang, Q. H. Liu, &amp;#8220;Frequency-Domain Reverse-Time Migration of Ground Penetrating Radar Based on Layered Medium Green's Functions&amp;#8221;, IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, vol. 11, no. 08, pp. 2957-2965, 2018.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

Instantaneous spectral attributes using scales in continuous-wavelet transform

Geophysics ◽  
2009 ◽  
Vol 74 (2) ◽  
pp. WA137-WA142 ◽  
Author(s):  
Satish Sinha ◽  
Partha Routh ◽  
Phil Anno
Keyword(s):  
Wavelet Transform ◽  
Frequency Spectrum ◽  
Continuous Wavelet Transform ◽  
Time Window ◽  
Frequency Resolution ◽  
Rock Properties ◽  
Center Frequency ◽  
Continuous Wavelet ◽  
Frequency Spectra ◽  
Time Frequency

Instantaneous spectral properties of seismic data — center frequency, root-mean-square frequency, bandwidth — often are extracted from time-frequency spectra to describe frequency-dependent rock properties. These attributes are derived using definitions from probability theory. A time-frequency spectrum can be obtained from approaches such as short-time Fourier transform (STFT) or time-frequency continuous-wavelet transform (TFCWT). TFCWT does not require preselecting a time window, which is essential in STFT. The TFCWT method converts a scalogram (i.e., time-scale map) obtained from the continuous-wavelet transform (CWT) into a time-frequency map. However, our method includes mathematical formulas that compute the instantaneous spectral attributes from the scalogram (similar to those computed from the TFCWT), avoiding conversion into a time-frequency spectrum. Computation does not require a predefined window length because it is based on the CWT. This technique optimally decomposes a multiscale signal. For nonstationary signal analysis, spectral decomposition from [Formula: see text] has better time-frequency resolution than STFT, so the instantaneous spectral attributes from CWT are expected to be better than those from STFT.

scholarly journals Spatial resolution enhancement of rotational-radar subsurface datasets using combined processing method

2021 ◽  
Vol 2090 (1) ◽  
pp. 012001
Author(s):  
Thomas McDonald ◽  
Mark Robinson ◽  
GuiYun Tian
Keyword(s):  
Spatial Resolution ◽  
Ground Penetrating Radar ◽  
Resolution Enhancement ◽  
Antenna System ◽  
Processing Method ◽  
Railway Tunnel ◽  
Cloud Data ◽  
Structural Health ◽  
Signal Processing Algorithms ◽  
Ground Penetrating

Abstract Effective visualisation of railway tunnel subsurface features (e.g. voids, utilities) provides critical insight into structural health and underpins planning of essential targeted predictive maintenance. Subsurface visualisation here utilises a rotating ground penetrating radar antenna system for 360° point cloud data capture. This technology has been constructed by our industry partner Railview Ltd, and requires the development of complimentary signal processing algorithms to improve feature localisation. The main novelty of this work is extension of Shrestha and Arai’s Combined Processing Method (CPM) to 360° Ground Penetrating Radar (360GPR) datasets, for first-time application in the context of railway tunnel structural health inspection. Initial experimental acquisition of a sample rotational transect for CPM enhancement is achieved by scanning a test section of tunnel sidewall - featuring predefined target geometry - with the rotating antenna. Next, frequency data separately undergo Inverse Fast Fourier Transform (IFFT) and Multiple Signal Classification (MUSIC) processing to recover temporal responses. Numerical implementation steps are explicitly provided for both MUSIC and two associated spatial smoothing algorithms, addressing an identified information deficit in the field. Described IFFT amplitude is combined with high spatial resolution of MUSIC via the CPM relation. Finally, temporal responses are compared qualitatively and quantitatively, evidencing the significant enhancement capabilities of CPM.

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