Real-time event location using model-based estimation of arrival times and back azimuths of seismic phases

Geophysics ◽  
2016 ◽  
Vol 81 (2) ◽  
pp. KS25-KS40 ◽  
Author(s):  
Nobuyasu Hirabayashi
Keyword(s):  
Hydraulic Fracturing ◽  
Real Time ◽  
Time Window ◽  
Signal To Noise Ratio ◽  
Estimation Method ◽  
Signal To Noise ◽  
Arrival Times ◽  
Event Location ◽  
Single Well ◽  
Noise Ratio

I have devised a real-time procedure for locating events using an estimation method that analyzes arrival times and back azimuths of phases. The new procedure is applicable to data acquired by local array receivers, such as those used in single-well monitoring as well as by dense receiver networks, and also to noisy waveforms, such as those observed in hydraulic fracturing monitoring if the signal-to-noise ratio is greater than approximately 6 dB. The new procedure uses coalescence microseismic mapping to obtain predictions of arrival times. Based on these predictions, arrival times were estimated by picking the maximum of the ratio of the short-term average to the long-term average of a characteristic function computed for waveforms in an appropriate time window. The estimated arrival times were used in a probabilistic location method, and the probability density function (PDF) of the event location was generated. To locate events for a local array of receivers, the PDFs of event back azimuths obtained using polarizations were combined with the traveltime data to remove directional ambiguities. I have developed this method to generate the PDF of event back azimuths using the average of polarization misfits, which are the differences of the measured and computed polarizations for trial event locations, weighted by the signal-to-noise ratio. Synthetic and field data examples of single-well monitoring of hydraulic fracturing, which required the estimation of event back azimuths in addition to arrival times, were evaluated to determine the effectiveness of the new procedure.

Weak Transient Electromagnetic Radiation Signal Detection Method Considering the New Watershed Image Segmentation Algorithm

2019 ◽  
Vol 34 (03) ◽  
pp. 2054009
Author(s):  
Wenjun Huo ◽  
Peng Chu ◽  
Kai Wang ◽  
Liangting Fu ◽  
Zhigang Niu ◽  
...  
Keyword(s):  
Electromagnetic Radiation ◽  
Cross Correlation ◽  
Detection Efficiency ◽  
Signal To Noise Ratio ◽  
Estimation Method ◽  
Detection Methods ◽  
Signal To Noise ◽  
Long Distance ◽  
Transient Electromagnetic ◽  
Noise Ratio

In order to study the detection methods of weak transient electromagnetic radiation signals, a detection algorithm integrating generalized cross-correlation and chaotic sequence prediction is proposed in this paper. Based on the dual-antenna test and cross-correlation information estimation method, the detection of aperiodic weak discharge signals under low signal-to-noise ratio is transformed into the estimation of periodic delay parameters, and the noise is reduced at the same time. The feasibility of this method is verified by simulation and experimental analysis. The results show that under the condition of low signal-to-noise ratio, the integrated method can effectively suppress the influence of 10 noise disturbances. It has a high detection probability for weak transient electromagnetic radiation signals, and needs fewer pulse accumulation times, which improves the detection efficiency and is more suitable for long-distance detection of weak electromagnetic radiation sources.

scholarly journals DOA Estimation for UCAs Based on Virtual Subarray Beamforming Technique

2018 ◽  
Vol 232 ◽  
pp. 01012
Author(s):  
Bo Xu ◽  
Zhigang Huang
Keyword(s):  
Signal To Noise Ratio ◽  
Estimation Method ◽  
Direction Of Arrival ◽  
Doa Estimation ◽  
Signal To Noise ◽  
Circular Arrays ◽  
Noise Ratio ◽  
Subarray Beamforming ◽  
Beamforming Technique

Direction-of-arrival (DOA) estimation is always a hotspot research in the fields of radar, sonar, communication and so on. And uniform circular arrays (UCAs) are more attractive in the context of DOA estimation since their symmetrical structures have potential to provide two directions coverage. This paper proposed a new DOA estimation method for UCAs via virtual subarray beamforming technique. The method would provide an acceptable DOA estimate even if the number of sources is great than the number of array elements. Also, the performance of the proposed method would hold good when the snapshot length or the signal-to-noise ratio (SNR) is small. Simulations show that the proposed technique offers significantly improved estimation resolution, capacity, and accuracy relative to the existing techniques.

Fault Detection Using Acoustic Methods for the Sodium-Water Reaction Monitoring in a Liquid Metal Reactor

2006 ◽  
Vol 321-323 ◽  
pp. 455-459
Author(s):  
Seop Hur ◽  
Seung Hwan Seong ◽  
Seong O Kim ◽  
Sang J. Lee
Keyword(s):  
Liquid Metal ◽  
Signal To Noise Ratio ◽  
System Modeling ◽  
Estimation Method ◽  
Acoustic Method ◽  
Liquid Sodium ◽  
High Signal ◽  
Signal To Noise ◽  
Liquid Metal Reactor ◽  
Noise Ratio

This study was aimed at developing a new method for detecting the sodium-water reaction as a result of a water leakage into the liquid sodium boundary for the liquid metal reactor. In the case of a passive acoustic method, to develop the leak detection algorithm, several signal processing methods have been evaluated. When the acoustic emission signal has a relatively high signal-to-noise ratio for the acoustic noises the spectral estimation method could be used to detect the sodium water reaction. In the case of a low signal-to-noise ratio within -5 dB to -15 dB, the system modeling and the identification methods using an autoregressive and an adaptive algorithm could be used to detect the sodium-water reaction. Regarding the active acoustic method, the basic attenuation factors of the ultrasonic beam were evaluated in the case of normal and abnormal plant conditions.

Assisted traveltime picking of crosshole GPR data

Geophysics ◽  
2009 ◽  
Vol 74 (4) ◽  
pp. J35-J48 ◽  
Author(s):  
Bernard Giroux ◽  
Abderrezak Bouchedda ◽  
Michel Chouteau
Keyword(s):  
Time Window ◽  
Signal To Noise Ratio ◽  
Real Data ◽  
Information Criterion ◽  
High Signal ◽  
Data Sets ◽  
Signal To Noise ◽  
Arrival Times ◽  
Common Time ◽  
Waveform Similarity

We introduce two new traveltime picking schemes developed specifically for crosshole ground-penetrating radar (GPR) applications. The main objective is to automate, at least partially, the traveltime picking procedure and to provide first-arrival times that are closer in quality to those of manual picking approaches. The first scheme is an adaptation of a method based on cross-correlation of radar traces collated in gathers according to their associated transmitter-receiver angle. A detector is added to isolate the first cycle of the radar wave and to suppress secon-dary arrivals that might be mistaken for first arrivals. To improve the accuracy of the arrival times obtained from the crosscorrelation lags, a time-rescaling scheme is implemented to resize the radar wavelets to a common time-window length. The second method is based on the Akaike information criterion(AIC) and continuous wavelet transform (CWT). It is not tied to the restrictive criterion of waveform similarity that underlies crosscorrelation approaches, which is not guaranteed for traces sorted in common ray-angle gathers. It has the advantage of being automated fully. Performances of the new algorithms are tested with synthetic and real data. In all tests, the approach that adds first-cycle isolation to the original crosscorrelation scheme improves the results. In contrast, the time-rescaling approach brings limited benefits, except when strong dispersion is present in the data. In addition, the performance of crosscorrelation picking schemes degrades for data sets with disparate waveforms despite the high signal-to-noise ratio of the data. In general, the AIC-CWT approach is more versatile and performs well on all data sets. Only with data showing low signal-to-noise ratios is the AIC-CWT superseded by the modified crosscorrelation picker.

Development and Characterization of an Electrocochleography-Guided Robotics-Assisted Cochlear Implant Array Insertion System

2021 ◽  
pp. 019459982110492
Author(s):  
Allan M. Henslee ◽  
Christopher R. Kaufmann ◽  
Matt D. Andrick ◽  
Parker T. Reineke ◽  
Viral D. Tejani ◽  
...  
Keyword(s):  
Cochlear Implant ◽  
Real Time ◽  
Signal To Noise Ratio ◽  
Electrode Array ◽  
High Signal ◽  
Animal Testing ◽  
Signal To Noise ◽  
Noise Ratio ◽  
Hearing Outcomes

Objective Electrocochleography (ECochG) is increasingly being used during cochlear implant (CI) surgery to detect and mitigate insertion-related intracochlear trauma, where a drop in ECochG signal has been shown to correlate with a decline in hearing outcomes. In this study, an ECochG-guided robotics-assisted CI insertion system was developed and characterized that provides controlled and consistent electrode array insertions while monitoring and adapting to real-time ECochG signals. Study Design Experimental research. Setting A research laboratory and animal testing facility. Methods A proof-of-concept benchtop study evaluated the ability of the system to detect simulated ECochG signal changes and robotically adapt the insertion. Additionally, the ECochG-guided insertion system was evaluated in a pilot in vivo sheep study to characterize the signal-to-noise ratio and amplitude of ECochG recordings during robotics-assisted insertions. The system comprises an electrode array insertion drive unit, an extracochlear recording electrode module, and a control console that interfaces with both components and the surgeon. Results The system exhibited a microvolt signal resolution and a response time <100 milliseconds after signal change detection, indicating that the system can detect changes and respond faster than a human. Additionally, animal results demonstrated that the system was capable of recording ECochG signals with a high signal-to-noise ratio and sufficient amplitude. Conclusion An ECochG-guided robotics-assisted CI insertion system can detect real-time drops in ECochG signals during electrode array insertions and immediately alter the insertion motion. The system may provide a surgeon the means to monitor and reduce CI insertion–related trauma beyond manual insertion techniques for improved CI hearing outcomes.

A Fast Block-Matching Motion Estimation Method Based on Difference Search Algorithm

2014 ◽  
Vol 610 ◽  
pp. 686-694
Author(s):  
Chang Jiang Liu ◽  
Chao Chen ◽  
A Fei Zhang ◽  
Xiao Lang Yan
Keyword(s):  
Motion Estimation ◽  
Search Algorithm ◽  
Signal To Noise Ratio ◽  
Estimation Method ◽  
Block Matching ◽  
Signal To Noise ◽  
Estimation Algorithms ◽  
Diamond Search ◽  
Simulation Results ◽  
Noise Ratio

The diamond search (DS) algorithm is one of the most efficient block matching motion estimation algorithms by far and has already been applied in MPEG2/4. Through our research, we found that there is still some redundancy in the algorithm. In this paper, an improved new difference based search (DBS) algorithm is proposed. Simulation results demonstrate that the new algorithm outperforms the well-known diamond search (DS) algorithm and four step-searches (4SS). It obtains almost the same Peak Signal to Noise Ratio (PSNR) while requires less computations than the DS algorithm and 4SS algorithm.

Sign in / Sign up

Export Citation Format

Share Document