Defect Classification in Pipes by Neural Networks Using Multiple Guided Ultrasonic Wave Features Extracted After Wavelet Processing

2005 ◽  
Vol 127 (3) ◽  
pp. 294-303 ◽  
Author(s):  
Piervincenzo Rizzo ◽  
Ivan Bartoli ◽  
Alessandro Marzani ◽  
Francesco Lanza di Scalea
Keyword(s):  
Guided Waves ◽  
Fourier Transforms ◽  
Damage Index ◽  
Classification Performance ◽  
Discrete Wavelet ◽  
Cross Sectional ◽  
Classification Framework ◽  
Discrete Wavelet Decomposition ◽  
Good Classification ◽  
Good Classification Performance

This paper casts pipe inspection by ultrasonic guided waves in a feature extraction and automatic classification framework. The specific defect under investigation is a small notch cut in an ASTM-A53-F steel pipe at depths ranging from 1% to 17% of the pipe cross-sectional area. A semi-analytical finite element method is first used to model wave propagation in the pipe. In the experiment, reflection measurements are taken and six features are extracted from the discrete wavelet decomposition of the raw signals and from the Hilbert and Fourier transforms of the reconstructed signals. A six-dimensional damage index is then constructed, and it is fed to an artificial neural network that classifies the size and the location of the notch. Overall, the wavelet-based multifeature analysis demonstrates good classification performance and robustness against noise and changes in some of the operating parameters.

Combined RF-based drone detection and classification

2021 ◽  
Author(s):  
Sanjoy Basak ◽  
Sreeraj Rajendran ◽  
Sofie Pollin ◽  
Bart Scheers
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Goodness Of Fit ◽  
Detailed Comparison ◽  
Classification Performance ◽  
Classification Framework ◽  
Good Classification ◽  
Good Classification Performance ◽  
Transmitted Signal ◽  
Combined Detection

Despite several beneficial applications, unfortunately, drones are also being used for illicit activities such as drug trafficking, firearm smuggling or to impose threats to security-sensitive places like airports and nuclear power plants. The existing drone localization and neutralization technologies work on the assumption that the drone has already been detected and classified. Although we have observed a tremendous advancement in the sensor industry in this decade, there is no robust drone detection and classification method proposed in the literature yet. This paper focuses on radio frequency (RF) based drone detection and classification using the frequency signature of the transmitted signal. We have created a novel drone RF dataset using commercial drones and presented a detailed comparison between a two-stage and combined detection and classification framework. The detection and classification performance of both frameworks are presented for a single-signal and simultaneous multi-signal scenario. With detailed analysis, we show that You Only Look Once (YOLO) framework provides better detection performance compared to the Goodness-of-Fit (GoF) spectrum sensing for a simultaneous multi-signal scenario and good classification performance comparable to Deep Residual Neural Network (DRNN) framework.<br>

scholarly journals Combined RF-based drone detection and classification

2021 ◽  
Author(s):  
Sanjoy Basak ◽  
Sreeraj Rajendran ◽  
Sofie Pollin ◽  
Bart Scheers
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Goodness Of Fit ◽  
Detailed Comparison ◽  
Classification Performance ◽  
Classification Framework ◽  
Good Classification ◽  
Good Classification Performance ◽  
Transmitted Signal ◽  
Combined Detection

Despite several beneficial applications, unfortunately, drones are also being used for illicit activities such as drug trafficking, firearm smuggling or to impose threats to security-sensitive places like airports and nuclear power plants. The existing drone localization and neutralization technologies work on the assumption that the drone has already been detected and classified. Although we have observed a tremendous advancement in the sensor industry in this decade, there is no robust drone detection and classification method proposed in the literature yet. This paper focuses on radio frequency (RF) based drone detection and classification using the frequency signature of the transmitted signal. We have created a novel drone RF dataset using commercial drones and presented a detailed comparison between a two-stage and combined detection and classification framework. The detection and classification performance of both frameworks are presented for a single-signal and simultaneous multi-signal scenario. With detailed analysis, we show that You Only Look Once (YOLO) framework provides better detection performance compared to the Goodness-of-Fit (GoF) spectrum sensing for a simultaneous multi-signal scenario and good classification performance comparable to Deep Residual Neural Network (DRNN) framework.<br>

IMPROVING SVM PERFORMANCE IN MULTI-LABEL DOMAINS: THRESHOLD ADJUSTMENT

2013 ◽  
Vol 22 (01) ◽  
pp. 1250038 ◽  
Author(s):  
PEERAPON VATEEKUL ◽  
SAREEWAN DENDAMRONGVIT ◽  
MIROSLAV KUBAT
Keyword(s):  
Classification Performance ◽  
Support Vector ◽  
Binary Classifier ◽  
Research Groups ◽  
Computational Costs ◽  
Vector Machines ◽  
Threshold Adjustment ◽  
Good Classification ◽  
Good Classification Performance ◽  
Suboptimal Behavior

In “multi-label domains,” where the same example can simultaneously belong to two or more classes, it is customary to induce a separate binary classifier for each class, and then use them all in parallel. As a result, some of these classifiers are induced from imbalanced training sets where one class outnumbers the other – a circumstance known to hurt some machine learning paradigms. In the case of Support Vector Machines (SVM), this suboptimal behavior is explained by the fact that SVM seeks to minimize error rate, a criterion that is in domains of this type misleading. This is why several research groups have studied mechanisms to readjust the bias of SVM's hyperplane. The best of these achieves very good classification performance at the price of impractically high computational costs. We propose here an improvement where these cost are reduced to a small fraction without significantly impairing classification.

scholarly journals Training Classifiers under Covariate Shift by Constructing the Maximum Consistent Distribution Subset

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Xu Yu ◽  
Miao Yu ◽  
Li-xun Xu ◽  
Jing Yang ◽  
Zhi-qiang Xie
Keyword(s):  
Subset Selection ◽  
Feature Space ◽  
Classification Performance ◽  
Selection Method ◽  
Experimental Results ◽  
Training Set ◽  
Traditional Methods ◽  
Generalization Ability ◽  
Good Classification ◽  
Good Classification Performance

The assumption that the training and testing samples are drawn from the same distribution is violated under covariate shift setting, and most algorithms for the covariate shift setting try to first estimate distributions and then reweight samples based on the distributions estimated. Due to the difficulty of estimating a correct distribution, previous methods can not get good classification performance. In this paper, we firstly present two types of covariate shift problems. Rather than estimating the distributions, we then desire an effective method to select a maximum subset following the target testing distribution based on feature space split from the auxiliary set or the target training set. Finally, we prove that our subset selection method can consistently deal with both scenarios of covariate shift. Experimental results demonstrate that training a classifier with the selected maximum subset exhibits good generalization ability and running efficiency over those of traditional methods under covariate shift setting.

scholarly journals Coupled Least Squares Support Vector Ensemble Machines

Information ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 195 ◽  
Author(s):  
Dickson Keddy Wornyo ◽  
Xiang-Jun Shen
Keyword(s):  
Least Squares ◽  
Classification Performance ◽  
Support Vector ◽  
Vector Method ◽  
Wide Range ◽  
Good Classification ◽  
Coupling Strategy ◽  
Good Classification Performance ◽  
Data Driven Modeling ◽  
Model Approach

The least squares support vector method is a popular data-driven modeling method which shows better performance and has been successfully applied in a wide range of applications. In this paper, we propose a novel coupled least squares support vector ensemble machine (C-LSSVEM). The proposed coupling ensemble helps improve robustness and produce good classification performance than the single model approach. The proposed C-LSSVEM can choose appropriate kernel types and their parameters in a good coupling strategy with a set of classifiers being trained simultaneously. The proposed method can further minimize the total loss of ensembles in kernel space. Thus, we form an ensemble regressor by co-optimizing and weighing base regressors. Experiments conducted on several datasets such as artificial datasets, UCI classification datasets, UCI regression datasets, handwritten digits datasets and NWPU-RESISC45 datasets, indicate that C-LSSVEM performs better in achieving the minimal regression loss and the best classification accuracy relative to selected state-of-the-art regression and classification techniques.

Application of WAVELET-SVM in Fault Diagnosis for the UV Control System

2011 ◽  
Vol 65 ◽  
pp. 199-203
Author(s):  
Sheng Wu Wang ◽  
Xiu Hua Shi ◽  
Hui Xu ◽  
Zhao Jing Tong
Keyword(s):  
Control System ◽  
Fault Diagnosis ◽  
Wavelet Transformation ◽  
Classification Performance ◽  
Support Vector ◽  
Fault Features ◽  
Good Classification ◽  
Good Classification Performance ◽  
Simulation Results ◽  
Fault Characteristic

Wavelet Analysis extracts the main feature from the fault signal through wavelet transformation, so it is advantageous to withdraw fault characteristic for fault diagnosis. Support Vector Machine (SVM) has shown its good classification performance in fault diagnosis. A new method of fault diagnosis for UV control system based on WAVELET-SVM is raised. The sensor output is sampled in frequency domain and it is preprocessed by wavelet to extract main vectors of the fault features. Fault patterns under various states are classified using multi-class SVM, and fault diagnosis is realized. The simulation results show that WAVELET-SVM is feasible to detect and locate faults quickly and exactly and has high robustness.

scholarly journals Ultrasonic Guided Waves-Based Monitoring of Rail Head: Laboratory and Field Tests

2010 ◽  
Vol 2010 ◽  
pp. 1-13 ◽  
Author(s):  
Piervincenzo Rizzo ◽  
Marcello Cammarata ◽  
Ivan Bartoli ◽  
Francesco Lanza di Scalea ◽  
Salvatore Salamone ◽  
...  
Keyword(s):  
Wavelet Transform ◽  
Guided Waves ◽  
Detection System ◽  
Damage Index ◽  
Ultrasonic Guided Waves ◽  
Inspection System ◽  
Discrete Wavelet ◽  
Outlier Analysis ◽  
Rail Head ◽  
Rail Inspection

Recent train accidents have reaffirmed the need for developing a rail defect detection system more effective than that currently used. One of the most promising techniques in rail inspection is the use of ultrasonic guided waves and noncontact probes. A rail inspection prototype based on these concepts and devoted to the automatic damage detection of defects in rail head is the focus of this paper. The prototype includes an algorithm based on wavelet transform and outlier analysis. The discrete wavelet transform is utilized to denoise ultrasonic signals and to generate a set of relevant damage sensitive data. These data are combined into a damage index vector fed to an unsupervised learning algorithm based on outlier analysis that determines the anomalous conditions of the rail. The first part of the paper shows the prototype in action on a railroad track mock-up built at the University of California, San Diego. The mock-up contained surface and internal defects. The results from three experiments are presented. The importance of feature selection to maximize the sensitivity of the inspection system is demonstrated here. The second part of the paper shows the results of field testing conducted in south east Pennsylvania under the auspices of the U.S. Federal Railroad Administration.

scholarly journals Advanced Ultrasonic Structural Monitoring of Waveguides

2008 ◽  
Vol 56 ◽  
pp. 477-482
Author(s):  
M. Cammarata ◽  
D. Dutta ◽  
Hoon Sohn ◽  
P. Rizzo ◽  
Kent A. Harries
Keyword(s):  
Lead Zirconate Titanate ◽  
Structural Damage ◽  
Fatigue Cracks ◽  
Linear Method ◽  
Damage Index ◽  
High Sensitivity ◽  
Nonlinear Acoustics ◽  
Lead Zirconate ◽  
Discrete Wavelet ◽  
Cross Sectional

Ultrasonic Guided Waves (UGWs) are a useful tool in those structural health monitoring applications that can benefit from built-in transduction, moderately large inspection ranges and high sensitivity to small flaws. This paper describes two methods, based on linear and nonlinear acoustics for structural damage detection based on UGWs. The linear method combine the advantages of UGW inspection with the outcomes of the Discrete Wavelet Transform (DWT) that is used for extracting defect-sensitive features that can be combined to perform a multivariate diagnosis of damage. In particular, the DWT is exploited to generate a set of relevant wavelet coefficients to construct a uni-dimensional or multi-dimensional damage index that, in turn is fed to an outlier algorithm to detect anomalous structural states. The nonlinear acoustics method exploits the circumstance that a cracked medium exhibits high acoustic nonlinearity which is manifested as harmonics in the power spectrum of the received signal. Experimental results also indicate that the harmonic components increase non-linearly in magnitude with increasing amplitude of the input signal. The proposed nonlinear technique identifies the presence of cracks by looking at the harmonics and their nonlinear relationship to the input amplitude. The general framework presented in this paper is applied to the detection of fatigue cracks in an I-shaped steel beam. The probing hardware consists of Lead Zirconate Titanate (PZT) materials used for both ultrasound generation and detection at chosen frequency. The effectiveness of the proposed methods for the structural diagnosis of defects that are small compared to the waveguide cross-sectional area is discussed.

scholarly journals A Study on Enhancement of Fish Recognition Using Cumulative Mean of YOLO Network in Underwater Video Images

2020 ◽  
Vol 8 (11) ◽  
pp. 952
Author(s):  
Jin-Hyun Park ◽  
Changgu Kang
Keyword(s):  
Classification Performance ◽  
Current Frame ◽  
Exotic Invasive Species ◽  
Video Images ◽  
Underwater Environment ◽  
Good Classification ◽  
Exotic Invasive ◽  
Rare And Endangered ◽  
Good Classification Performance ◽  
Classification Probability

In the underwater environment, in order to preserve rare and endangered objects or to eliminate the exotic invasive species that can destroy the ecosystems, it is essential to classify objects and estimate their number. It is very difficult to classify objects and estimate their number. While YOLO shows excellent performance in object recognition, it recognizes objects by processing the images of each frame independently of each other. By accumulating the object classification results from the past frames to the current frame, we propose a method to accurately classify objects, and count their number in sequential video images. This has a high classification probability of 93.94% and 97.06% in the test videos of Bluegill and Largemouth bass, respectively. The proposed method shows very good classification performance in video images taken of the underwater environment.

Generic Object Detection Based on Boosting Embedded with Bag-of-Words

2011 ◽  
Vol 109 ◽  
pp. 285-289
Author(s):  
Xue Na Qiu ◽  
Shi Rong Liu ◽  
Jia Tao Song
Keyword(s):  
Object Detection ◽  
Detection Efficiency ◽  
Classification Performance ◽  
Complex Object ◽  
Detection Accuracy ◽  
Bag Of Words ◽  
Good Classification ◽  
Local Patch ◽  
Good Classification Performance ◽  
Boosting Method

This paper studies generic object detection. In the view of complexity and diversity of generic object, it proposes Boosting generic object detection method with bag-of-words. Boosting method has good detection efficiency, but it has some fault detections due to the diversity and complexity of the object. While Bag-of-words method has some advantages, such as local patch features, simplicity and robustness, and it has good classification performance of complex object. The proposed method applies Bag-of-words to remove the fault detection and to improve the tracking results of Boosting, and thus it achieves high generic object detection accuracy.

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