scholarly journals Monitoring Vehicles on Highway by Dual-Channel φ-OTDR

2020 ◽  
Vol 10 (5) ◽  
pp. 1839 ◽  
Author(s):  
Shaohua Xu ◽  
Zujun Qin ◽  
Wentao Zhang ◽  
Xianming Xiong
Keyword(s):  
Noise Suppression ◽  
Single Channel ◽  
Strong Dependence ◽  
Vibration Signal ◽  
Differential Method ◽  
Step Size ◽  
Distributed Sensor ◽  
Optical Time Domain Reflectometer ◽  
Dual Channel ◽  
Vibration Detection

As a fully distributed sensor, the phase-sensitive optical time domain reflectometer (φ-OTDR) has attracted remarkable attention in real-time vibration detection. We present a dual-channel φ-OTDR (DC-φ-OTDR), formed by two single-channel φ-OTDRs (SC-φ-OTDR), to monitor running vehicles on a highway. In the double-channel system, an improved algorithm (will be referred to as the CDM&V) is proposed to alleviate the strong dependence of vibration detection on the differential step as in the widely used conventional differential method (CDM). The DC-φ-OTDR is first tested over campus road before applying it to locate moving vehicles on the highway. For comparison purposes, both the DC-φ-OTDR and SC-φ-OTDR are used to monitor the vehicles with respective signal processing methods of the CDM and CDM&V. The experimental results at campus show that the dual-path scheme can undoubtedly reduce vibration misjudgment relative to the single one due to the very small possibility of false measurements occurred simultaneously at the same location in both channels. In signal demodulation, the CDM&V greatly relaxes the constraints on the differencing interval for identifying the vehicle-caused vibration. With a step size of 5 or lower, the CDM fails to locate the running vehicle at z=~8.5 km, but the CDM&V successfully demonstrates the feasible capability of locating the vibration. With an increase in the differential interval, both the CDM and CDM&V are able to detect the vibration signal, but with the latter showing a much better noise suppression performance and hence a larger SNR. Importantly, in comparison with the SC-φ-OTDR system, the DC-φ-OTDR exhibits a considerable enhanced SNR for the detection signal regardless of which processing algorithm (i.e., CDM, CDM&V) is used. The vehicle locations positioned by the DC-φ-OTDR are confirmed by the monitoring cameras.

scholarly journals Rolling Bearing Fault Diagnosis Based on Component Screening Vector Local Characteristic-Scale Decomposition

2022 ◽  
Vol 2022 ◽  
pp. 1-13
Author(s):  
Tengfei Guan ◽  
Shijun Liu ◽  
Wenbo Xu ◽  
Zhisheng Li ◽  
Hongtao Huang ◽  
...  
Keyword(s):  
Fault Diagnosis ◽  
Single Channel ◽  
Simulation Analysis ◽  
Vibration Signal ◽  
Rolling Bearing ◽  
Local Characteristic ◽  
Characteristic Scale ◽  
Dual Channel ◽  
Component Selection ◽  
Envelope Spectrum

The fault vibration signal of a bearing has nonstationary and nonlinear characteristics and can be regarded as the combination of multiple amplitude- and frequency-modulation components. The envelope of a single component contains the fault characteristics of a bearing. Local characteristic-scale decomposition (LCD) can decompose the vibration signal into a series of multiple intrinsic scale components. Some components can clearly reflect the running state of a bearing, and fault diagnosis is conducted according to the envelope spectrum. However, the conventional LCD takes a single-channel signal as the research object, which cannot fully reflect the characteristic information of the rotor, and the analysis results based on different channel signals of the same section will be inconsistent. To solve this problem, based on full vector spectrum technology, the homologous dual-channel information is fused. A vector LCD method based on cross-correlation coefficient component selection is given, and a simulation analysis is completed. The effectiveness of the proposed method is verified by simulated signals and experimental signals of a bearing, which provides a method for bearing feature extraction and fault diagnosis.

SAR Image Segmentation Based on Maximum Variance Method and Morphology

2013 ◽  
Vol 798-799 ◽  
pp. 761-764
Author(s):  
Ming Xia Xiao
Keyword(s):  
Image Segmentation ◽  
Noise Suppression ◽  
Operation Time ◽  
Differential Method ◽  
Good Effect ◽  
Sar Image ◽  
Variance Method ◽  
Maximum Variance ◽  
Sar Image Segmentation ◽  
A New Technique

A new technique that combines maximum variance method and morphology was presented for Synthetic Aperture Radar (SAR) image segmentation in target detection. Firstly, using the first-order differential method to enhance the original image for highlighting edge details of the image; then using the maximum variance method to calculate the gray threshold and segment the image; lastly, the mathematical morphology was used to processing the segmented image, which could prominently improve the segmentation effects. Experiments show that this algorithm can obtain accurate segmentation results, and have a good effect on noise suppression, edge detail protection and operation time.

Application of complex-trace analysis to seismic data for random-noise suppression and temporal resolution improvement

Geophysics ◽  
2006 ◽  
Vol 71 (3) ◽  
pp. V79-V86 ◽  
Author(s):  
Hakan Karsli ◽  
Derman Dondurur ◽  
Günay Çifçi
Keyword(s):  
Seismic Data ◽  
Trace Analysis ◽  
Noise Suppression ◽  
Single Channel ◽  
Random Noise ◽  
Synthetic Data ◽  
Low Frequency ◽  
Bright Spot ◽  
Phase Information ◽  
Resolution Improvement

Time-dependent amplitude and phase information of stacked seismic data are processed independently using complex trace analysis in order to facilitate interpretation by improving resolution and decreasing random noise. We represent seismic traces using their envelopes and instantaneous phases obtained by the Hilbert transform. The proposed method reduces the amplitudes of the low-frequency components of the envelope, while preserving the phase information. Several tests are performed in order to investigate the behavior of the present method for resolution improvement and noise suppression. Applications on both 1D and 2D synthetic data show that the method is capable of reducing the amplitudes and temporal widths of the side lobes of the input wavelets, and hence, the spectral bandwidth of the input seismic data is enhanced, resulting in an improvement in the signal-to-noise ratio. The bright-spot anomalies observed on the stacked sections become clearer because the output seismic traces have a simplified appearance allowing an easier data interpretation. We recommend applying this simple signal processing for signal enhancement prior to interpretation, especially for single channel and low-fold seismic data.

Monaural Versus Binaural Discrimination for Normal Listeners

1963 ◽  
Vol 6 (3) ◽  
pp. 263-269 ◽  
Author(s):  
Richard G. Chappell ◽  
James F. Kavanagh ◽  
Stanley Zerlin
Keyword(s):  
Single Channel ◽  
Normal Hearing ◽  
Dual Channel ◽  
Recording Session ◽  
Monosyllabic Words ◽  
Image Separation ◽  
Test Materials ◽  
The Difference

Normal hearing adults demonstrated approximately 20% better intelligibility scores for monosyllabic words presented binaurally (with a background of conversation) than to these words presented monaurally. The test materials were recorded on dual-channel tape through two head-mounted microphones. These microphones were directed toward each of three speakers who in turn produced the monosyllabic words while two simultaneous conversations were carried on by four other participants. Throughout the recording session the experimenters attempted to preserve as naturalistic a situation as possible. The 18 subjects with normal hearing listened through earphones to a single channel of this tape presented monaurally and to both channels delivered binaurally. The difference between the monaural and binaural intelligibility scores is discussed in terms of image-separation in space.

Research of Ni-Mn-Ga Shape Memory Alloy Based Mechanical Vibration Detection Device

2014 ◽  
Vol 1006-1007 ◽  
pp. 845-848
Author(s):  
Yong Zhi Cai
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Mechanical Vibration ◽  
Vibration Signal ◽  
Experimental Results ◽  
Vibration Measurements ◽  
Vibration Detection ◽  
Vibration Sensing

The study explores the vibration sensing effect of Ni-Mn-Ga shape memory alloy, based on the experimental results, researched the characteristics of this alloy applied in mechanical vibration signal sensors, and describes the feasibility of this alloy used for vibration measurements.

scholarly journals Speed Calibration and Traceability for Train-Borne 24 GHz Continuous-Wave Doppler Radar Sensor

Sensors ◽  
2020 ◽  
Vol 20 (4) ◽  
pp. 1230
Author(s):  
Lei Du ◽  
Qiao Sun ◽  
Jie Bai ◽  
Xiaolei Wang ◽  
Tianqi Xu
Keyword(s):  
Continuous Wave ◽  
Doppler Radar ◽  
Single Channel ◽  
Full Range ◽  
Calibration Method ◽  
Simulation System ◽  
Radar Sensor ◽  
Dual Channel ◽  
Calibration Methods ◽  
24 Ghz

The 24 GHz continuous-wave (CW) Doppler radar sensor (DRS) is widely used for measuring the instantaneous speed of moving objects by using a non-contact approach, and has begun to be used in train-borne movable speed measurements in recent years in China because of its advanced performance. The architecture and working principle of train-borne DRSs with different structures including single-channel DRSs used for freight train speed measurements in railway freight dedicated lines and dual-channel DRSs used for speed measurements of high-speed and urban rail trains in railway passenger dedicated lines, are first introduced. Then, the disadvantages of two traditional speed calibration methods for train-borne DRS are described, and a new speed calibration method based on the Doppler shift signal simulation by imposing a signal modulation on the incident CW microwave signal is proposed. A 24 GHz CW radar target simulation system for a train-borne DRS was specifically realized to verify the proposed speed calibration method for a train-borne DRS, and traceability and performance evaluation on simulated speed were taken into account. The simulated speed range of the simulation system was up to (5~500) km/h when the simulated incident angle range was within the range of (45 ± 8)°, and the maximum permissible error (MPE) of the simulated speed was ±0.05 km/h. Finally, the calibration and uncertainty evaluation results of two typical train-borne dual-channel DRS samples validated the effectiveness and feasibility of the proposed speed calibration approach for a train-borne DRS with full range in the laboratory as well as in the field.

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