Improved Distance Evaluation Research Articles

Fully automated operational modal identification of regular and irregular buildings with ensemble learning

Modal identification, a type of system identification that employs modal analysis, can be automated to reduce user interference in extracting modal parameters. Modal analysis is a valuable tool for obtaining a structure's modal parameters, which define its dynamic characteristics. Operational modal identification is a specific type of modal analysis that uses only system outputs to extract modal parameters. The present study aims to introduce a fully automated modal identification algorithm to identify modal parameters for an unknown system based on its output information. The algorithm uses a stochastic subspace algorithm to extract modal parameters, requiring only the appropriate degree of the state-space model estimated using the Singular Value Criterion. Several features are used to create a feature space that separates physical and spurious modes. The Improved Distance Evaluation algorithm selects appropriate features, making the identification process more accurate and flexible. The identification algorithm employs clustering algorithms with different approaches and the Dempster-Shafer data fusion algorithm to integrate clustering algorithm results and avoid divergence among them. Due to limited data diversity for identification in cases where only one dataset is available, statistical resampling methods are used as an alternative. The proposed algorithm can identify modal parameters using only one dataset of the building structure. Signal processing, data collection, clustering, feature extraction, model reduction, and data fusion are all aspects of this algorithm. To assess its performance, four regular and irregular buildings are considered as case studies. The presented modal identification algorithm is highly accurate and robust with the repeatable result as compared to similar algorithms, with extracted modal parameters demonstrating high stability.

Determination of moisture content and contaminated blank dried figs (Ficus carica L.) using dielectric property and artificial neural network

AbstractDried figs are a garden produce that must be graded after harvesting. Moisture levels and contaminated blank are two of the most critical effective elements on the marketability of dried figs, and they are highly related to fig quality. In the present research, an intelligent system was employed to classify dried figs based on moisture content levels and infected blank fruits. Capacitance characteristics, average diameter, and fruit area were all taken into account in this study. The dried fig dielectric constant was measured at six different frequency levels: 12, 22, 32, 42, 52, and 62 MHz. The best frequency was then chosen using the improved distance evaluation feature selection approach. Image processing was also used to determine the average diameter and area of the figures. Following that, the dielectric constant of the most effective frequency, the average diameter, and the area of the fruit were used as input parameters in the artificial neural network classification model to classify and describe the moisture and porosity level of the dried fig. The most essential dielectric constant information relating to moisture and porosity level was at frequencies of 22 and 52 MHz, respectively. Finally, classification accuracy of 95.7% for moisture and 91.3% for porosity level was attained. The results demonstrated the excellent performance and capabilities of the proposed approach for rating the internal quality of dried figs.

Early Detection of Avian Diseases Based on Thermography and Artificial Intelligence.

Non-invasive measures have a critical role in precision livestock and poultry farming as they can reduce animal stress and provide continuous monitoring. Animal activity can reflect physical and mental states as well as health conditions. If any problems are detected, an early warning will be provided for necessary actions. The objective of this study was to identify avian diseases by using thermal-image processing and machine learning. Four groups of 14-day-old Ross 308 Broilers (20 birds per group) were used. Two groups were infected with one of the following diseases: Newcastle Disease (ND) and Avian Influenza (AI), and the other two were considered control groups. Thermal images were captured every 8 h and processed with MATLAB. After de-noising and removing the background, 23 statistical features were extracted, and the best features were selected using the improved distance evaluation method. Support vector machine (SVM) and artificial neural networks (ANN) were developed as classifiers. Results indicated that the former classifier outperformed the latter for disease classification. The Dempster-Shafer evidence theory was used as the data fusion stage if neither ANN nor SVM detected the diseases with acceptable accuracy. The final SVM-based framework achieved 97.2% and 100% accuracy for classifying AI and ND, respectively, within 24 h after virus infection. The proposed method is an innovative procedure for the timely identification of avian diseases to support early intervention.

Diagnosis of Sensor Faults in Hypersonic Vehicles Using Wavelet Packet Translation Based Support Vector Regressive Classifier

In this article, a fault diagnosis scheme based on the data-driven approach of hypersonic vehicles (HVs) is studied. First, the fault features are obtained by wavelet packet translation (WPT) processing. Second, an improved distance evaluation technique (DET) based on Spearman correlation analysis is used to select features and reduce dimensions. The designed enhanced WPT-DET (EWPT-DET) method can extract sensitive features based on self-defined attention coefficients. Third, the fault pattern recognition process is achieved by support vector regression (SVR) with genetic algorithm optimization. The SVR classifier with high dimensional linear fitting ability is very suitable for HVs' reaction control system with sensor faults. The method is further used in locating and diagnosing multisensor fusion faults. Moreover, the fault occurrence time of single sensor timing faults is judged. Finally, simulation studies are provided to illustrate the enhanced performance of the proposed approach.

Feature Classification Method of Frequency Cepstrum Coefficient Based On Weighted Extreme Gradient Boosting

Cepstrum coefficient and decision tree classification provide a feasible method for mechanical fault diagnosis. However, this method has the problems of low accuracy of feature extraction and low reliability of feature classification. The efficiency and classification results of this method are not ideal. Therefore, this paper proposes a feature classification method of frequency cepstrum coefficients based on weighted extreme gradient boosting. The proposed method is mainly divided into two parts: feature extraction and feature classification. In the part of feature extraction, Considering the limitation of Mel frequency scale in MFCC, an adaptive frequency cepstrum coefficient (AFCC) method is proposed, which can adaptively obtain the frequency scale of the corresponding signal, thus improving the feature accuracy extracted by MFCC method. In the aspect of feature classification, XGboost algorithm has strong learning ability, which easily leads to over fitting and affects the classification accuracy, A weighted extreme gradient boosting (WXGB) method is proposed, and an improved distance evaluation method (IDE) is introduced to modify the feature weights learned by XGboost, so as to improve the prediction accuracy of the classification model. In order to verify the effectiveness of the method, the vibration signals of rolling bearings with different fault types are taken as samples to carry out feature extraction and classification. The results of feature extraction and classification of different methods are compared, and the effectiveness of the proposed feature classification method based on weighted extremum gradient boosting frequency cepstrum coefficient in rolling bearing fault diagnosis is verified.

Bearing remaining useful life prediction under starved lubricating condition using time domain acoustic emission signal processing

In this paper, the estimation of the remaining useful life (RUL) of angular contact ball bearing using time-domain signal processing method is discussed. An experimental setup based on acoustic emission (AE) signal is used to extract and collect the desired data. The residual life test is performed on the SKF 7202 BEP angular contact ball bearing. Sixty-time domain features have been introduced and used for fault detection. Improved Distance Evaluation (IDE) method has been used for feature dimensionality reduction and the best 10 features have been selected. K-Nearest Neighbors (KNN) algorithm has been used to investigate the classification accuracy of IDE based on selected features for classifying healthy and faulty bearings. The results show that the IDE method enables natural fault detection in bearings with high precision. To validate the performance of the KNN classifier, performance indices such as accuracy, precision, and specificity are applied. The results show that kurtosis, FM4, k factor, energy, and peak are the best features and kurtosis has the highest KNN rank with accuracy, precision, and specificity of 97%, 93%, and 94%, respectively.

Extraction of the structural mode shapes utilizing image processing method and data fusion

Dynamic properties of structures, such as natural frequency, mode shapes, and damping ratios, play a decisive role in the structural behavior against dynamic loads such as earthquakes. One of the utilizations of these properties is the determination of the earthquake forces imposed on structures based on the design spectra. Other applications of these features could be utilized to update the finite element model, detect damage in structures, and long-term health-monitoring of the structures. So, accuracy and reducing the cost of evaluating these properties would have a significant role in increasing the efficiency and the consequences of the useful life of the structures. Image processing is one of the methods for determination of dynamic properties of structures. The aim of this article is presenting a data fusion method to improve the accuracy of extraction of the mode shapes by image processing. For this purpose, a cantilever aluminum beam and a Three-story frame with additional mass have been considered, then their vibration was recorded utilizing the image processing method. To extract dynamic properties of structure, peak survey method was used. The proposed average method in signal level and Improved Distance Evaluation (IDE) in feature level were utilized to improve the accuracy of obtained mode shapes. The accuracy of the novel technique was investigated by comparing the seismic properties to the results from the accelerometer sensors and the finite element method. The results show that this method could enhance the accuracy of the image processing method for remote sensing.

A road quality classification technique based on vehicle system responses with experimental validation

Aiming at estimating the road surface condition with improvement of the accuracy in spatial, this paper proposes a new method to classify road surface condition by considering identification interval based on vehicle system responses. First, the response signals in different vehicle speeds are decomposed by using both Wavelet Transform (WT) and Empirical Mode Decomposition (EMD) techniques. Then characteristics of the signals in both the time and decomposed frequency domain are subsequently extracted. An Improved Distance Evaluation Technique (IDET) is used to select superior features from the characteristics. Finally, a Support Vector Machine (SVM) classifier is applied to determine the road classification. The influences of identification intervals in spatial accuracy are discussed, and an adaptive classification interval was proposed to improve accuracy. The algorithm is validated by using both simulation and experimental results.

Sensor placement optimization in the artificial lateral line using optimal weight analysis combining feature distance and variance evaluation

Artificial lateral line is a multi-sensor system, mimicking the lateral line of fish to perceive the parameters of flow field. However, it can easily lead to information loss or redundancy with limited number of sensors due to unsuitable sensor placement. An optimal weight analysis algorithm is proposed to solve the problem on sensor placement of robotic fish. Firstly, signal features are extracted from the pressure data, which are collected from candidate sensor locations in different conditions. Then the improved distance evaluation is used to assess each feature, and the feature distance factor is regarded as the weight for distinguishing. Combined with the analysis of variance, the contribution vector of sensor locations is obtained. Three indexes selected by the algorithm are introduced to compare the sensor subsets. The results in both simulation and experiment show the effectiveness of the algorithm. The optimal number of sensors on the robotic fish is also studied.

Fault diagnosis of rotating machinery using wavelet-based feature extraction and support vector machine classifier

AbstractModern machine tools with high speed machining capabilities could place rotating shafts, gears, and bearings under extreme thermal, static, and impact stresses, potentially increasing their failure rates. In this research, a gearbox damage detection strategy based on discrete wavelet transform (DWT), wavelet packet transform (WPT), support vector machine (SVM), and artificial neural networks (ANN) is presented. Three case studies are conducted to compare the classification performance of SVM kernel functions and ANN. First, a fault detection analysis based on DWT and WPT is carried out to extract the damage information from the gearbox’s raw vibration signal. In this step, wavelet coefficients obtained from DWT are characterized using statistical calculations. Energy characteristics of the gearbox signal are acquired using WPT and their statistical characteristics are also computed. These three sets of information extracted from wavelet transforms are utilized as the input to SVM and ANN classifiers. Secondly, the improved distance evaluation technique (IDE) is implemented to select the sensitive input features for SVM and ANN. The penalty parameter C and kernel parameter γ in SVM are also optimized using the grid-search method. Finally, the optimized features and parameters are input into SVM and ANN algorithms to detect gearbox damage. The result shows that gearbox damage detection using energy characteristics extracted from WPT (Case 2) or their statistical values as input features (Case 3) to the learning algorithms produces higher classification accuracies than using statistical values of the DWT coefficients as inputs (Case 1). In addition, RBF-SVM has the best classification performance in Case 2 and 3 while Linear-SVM has the best classification accuracy rate in Case 1 in damage detection average.

An intelligent device for diagnosing avian diseases: Newcastle, infectious bronchitis, avian influenza

In commercial poultry production there are a number of diseases which are of particular importance due to the heavy economic losses that can arise if a flock becomes infected. The development of an automated and rapid disease detection system would therefore be of considerable benefit to both production and animal welfare. This study represents an intelligence device for diagnosing avian diseases by using Data-mining methods and Dempster-Shafer evidence theory (D-S). 14-day-old chickens were divided into four groups. Each group was deliberately infected with a disease: Newcastle Disease (ND), Bronchitis Virus (BV), Avian Influenenza (AI), and the last group was considered as control samples. Fast Fourier Transform (FFT) and Discrete Wavelet Transform (DWT) were used to process the chicken’s sound signals in frequency and time-frequency domains, respectively. In order to achieve information, 25 statistical features from frequency domains, and 75 statistical features from time-frequency domains were extracted. During dimensionality reduction stage, the best features of the sound signals were selected, using improved distance evaluation (IDE) method. The chicken’s sound signals were analyzed in two consecutive days after virus infection. Support vector machine (SVM) was used as the classifier in this study. The first classification was done with SVM and based on sound features in frequency and time-frequency domains with accuracy of 41.35 and 83.33%, respectively. The accuracy of the method based on D-S infusion of sound data reached 91.15%. The developed model based on achievement result could diagnose Newcastle Disease, Bronchitis Virus and Avian Influenza from sound signals.

Detection of inappropriate working conditions for the timing belt in internal-combustion engines using vibration signals and data mining

Abnormal operating conditions for the timing belt can lead to cracks, fatigue, sudden rupture and damage to engines. In this study, an intelligent system was developed to detect and classify high-load operating conditions and high-temperature operating conditions for timing belts. To achieve this, vibration signals in normal operating conditions, high-load operating conditions and high-temperature operating conditions were collected. Time-domain signals were transformed to the frequency domain and the time–frequency domain using the fast Fourier transform method and the wavelet transform method respectively. In the data-mining stage, 25 statistical features were extracted from different signal domains. The improved distance evaluation method was adopted to select the best features and to reduce the input space for the classifier. Then, the signal features from the time domain, the frequency domain and the time-frequency domain were fed into an artificial neural network to evaluate the accuracy of this designed procedure for detecting inappropriate operating conditions for the timing belt. Based on all these features extracted from the signals in the time, frequency and time–frequency domains, the artificial neural network classifier detected and classified normal operating conditions, high-load operating conditions and high-temperature operating conditions with accuracies of 73.3%, 85% and 89.2% respectively. The classification accuracies using features selected by improved distance evaluation in the signals from the time, frequency and time–frequency domains were found to be 85%, 95.8% and 95% respectively. The results showed that the developed system was capable of detecting and classifying both the normal operating conditions and abnormal operating conditions for the timing belt. The results also suggested that a combination of signal processing and feature selection can significantly enhance the classification accuracy.

Operation Reliability Assessment for Cutting Tools by Applying a Proportional Covariate Model to Condition Monitoring Information

The reliability of cutting tools is critical to machining precision and production efficiency. The conventional statistic-based reliability assessment method aims at providing a general and overall estimation of reliability for a large population of identical units under given and fixed conditions. However, it has limited effectiveness in depicting the operational characteristics of a cutting tool. To overcome this limitation, this paper proposes an approach to assess the operation reliability of cutting tools. A proportional covariate model is introduced to construct the relationship between operation reliability and condition monitoring information. The wavelet packet transform and an improved distance evaluation technique are used to extract sensitive features from vibration signals, and a covariate function is constructed based on the proportional covariate model. Ultimately, the failure rate function of the cutting tool being assessed is calculated using the baseline covariate function obtained from a small sample of historical data. Experimental results and a comparative study show that the proposed method is effective for assessing the operation reliability of cutting tools.

Gear Fault Identification Using Artificial Neural Network and Adaptive Neuro-Fuzzy Inference System

This study compares the performance of gear fault detection using Artificial Neural Networks (ANNs) and Adaptive Neuro-Fuzzy Inference System (ANFIS). The feature vector is extracted from vibration signals by standard deviation of wavelet packet coefficients at the fourth level. An improved distance evaluation technique is proposed for feature selection, and with it, the four salient features are selected from the original feature set. These features are normalized in the range zero to one and then fed into ANN and ANFIS. The gear conditions were considered to be healthy gearbox, slightly worn, and medium worn and broken-teeth gears faults. The output layer of ANN and ANFIS consists of one node indicating the status of the gearbox by four labels. A 3-layer Multi-Layer Perceptron (MLP) neural-network and an ANFIS were designed to carry out the task. The results show that the classification accuracy of ANFIS is better than MLP. Also, the effectiveness of the proposed feature selection method is demonstrated by the test results.

Application of Probabilistic Causal-effect Model based Artificial Fish-Swarm Algorithm for Fault Diagnosis in Mine Hoist

This paper presents an intelligent methodology for diagnosing incipient faults in mine hoist. As Probabilistic Causal-effect Model-Based diagnosis is an active branch of Artificial Intelligent, i n this paper, the feasibility of using probabilistic causal-effect model is studied and it is applied in artificial fish-swarm algorithm (AFSA) to classify the faults of mine hoist. In probabilistic causal-effect model, we employed probability function to nonlinearly map the data into a feature space, and with it, fault diagnosis is simplified into optimization problem from the original complex feature set. And an improved distance evaluation technique is proposed to identify different abnormal cases. The proposed approach is applied to fault diagnosis of friction hoist with many steel ropes, and testing results show that the proposed approach can reliably recognise different fault categories. Moreover, the effectiveness of the method of mapping hitting sets problem to 0/1 integer programming problem is also demonstrated by the testing results. It can get 95% to 100% minimal diagnosis with cardinal number of fault symptom sets greater than 20

Application of a modified fuzzy ARTMAP with feature-weight learning for the fault diagnosis of bearing

Considering different importance of the feature parameters to the fault conditions of bearing, a modified fuzzy ARTMAP (FAM) network model based on the feature-weight learning is presented in this paper. The features in time-domain, frequency-domain and wavelet-domain are extracted from the vibration signals to characterize the information relevant to the fault conditions of bearing. By the improved distance evaluation technique the optimal features are selected and the corresponding feature-weights which are assigned to the features to indicate their different importance to the fault conditions of bearing are obtained. Then they are combined with the modified FAM which is described by the weighted Manhattan distance and applied to the seven-class fault diagnosis of bearing. To assess the effectiveness and stability of the modified FAM network, bootstrapping method is employed to quantify the stability of the network performance statistically. Diagnosis results show that the modified FAM can more reliably and accurately recognize different fault classes.

Application of a Novel Hybrid Intelligent Method to Compound Fault Diagnosis of Locomotive Roller Bearings

To diagnose compound faults of locomotive roller bearings accurately, a novel hybrid intelligent diagnosis method is proposed in this paper. First of all, vibration signals are preprocessed to mine valid fault characteristic information. They are filtered and at the same time, they are decomposed by the empirical mode decomposition method and eight intrinsic mode functions (IMFs) are acquired. The filtered signals and IMFs are further demodulated to obtain their Hilbert envelope spectrums. Second, six feature sets are extracted, and they are time- and frequency-domain statistical features of the raw and preprocessed signals. Then, each feature set is evaluated and a few salient features are selected from it by applying the improved distance evaluation technique. Correspondingly, six salient feature sets are obtained. Finally, the six salient feature sets are, respectively, input into six classifiers based on adaptive neurofuzzy inference system (ANFIS), and genetic algorithm is employed to combine the outputs of the six ANFISs and to attain the final diagnosis result. The diagnosis results of the compound faults of the locomotive roller bearings verify that the proposed hybrid intelligent method may accurately recognize not only a single fault and fault severities but also compound faults.

Fault Diagnosis Based on Novel Hybrid Intelligent Model

In order to solve the difficult problem of identifying incipient fault and compound fault for mechanical equipment,and improve diagnosis accuracy,a novel hybrid intelligent diagnosis model based on multiple feature sets from different symptom domains and multiple classifier combination,is proposed.This model combines empirical mode decomposition(EMD),the improved distance evaluation technique,adaptive neuro-fuzzy inference system(ANTIS)and genetic algorithm(GA)techniques etc.Prior to feature extraction,several signal preprocessing techniques,i.e.filtration,EMD and demodulation etc.,are employed to excavate the underlying fault information from dynamic signals.Time-domain and frequency-domain statistical features that reflect the equipment operation conditions from various aspects are extracted and six feature sets are obtained.In succession,the improved distance evaluation technique is proposed,and with it,six sensitive feature sets are selected from the six original feature sets,respectively. The six sensitive feature sets are input into the multiple ANFISs combined by GA to attain the final diagnosis result.The application to fault diagnosis of locomotive wheel pair bearings shows the model is able to reliably recognize not only different fault categories and severities but also the compound faults.Thus,a desired diagnosis effect is obtained via the hybrid model.Moreover,the application result also validates the power of the proposed feature selection method based on the improved distance evaluation technique.

A new approach to intelligent fault diagnosis of rotating machinery

This paper presents a new approach to intelligent fault diagnosis based on statistics analysis, an improved distance evaluation technique and adaptive neuro-fuzzy inference system (ANFIS). The approach consists of three stages. First, different features, including time-domain statistical characteristics, frequency-domain statistical characteristics and empirical mode decomposition (EMD) energy entropies, are extracted to acquire more fault characteristic information. Second, an improved distance evaluation technique is proposed, and with it, the most superior features are selected from the original feature set. Finally, the most superior features are fed into ANFIS to identify different abnormal cases. The proposed approach is applied to fault diagnosis of rolling element bearings, and testing results show that the proposed approach can reliably recognise different fault categories and severities. Moreover, the effectiveness of the proposed feature selection method is also demonstrated by the testing results.

Fault diagnosis of rotating machinery based on multiple ANFIS combination with GAs

This paper presents a novel method for fault diagnosis based on empirical mode decomposition (EMD), an improved distance evaluation technique and the combination of multiple adaptive neuro-fuzzy inference systems (ANFISs). The method consists of three stages. First, prior to feature extraction, some preprocessing techniques, like filtration, demodulation and EMD are performed on vibration signals to acquire more fault characteristic information. Then, six feature sets, including time- and frequency-domain statistical features of both the raw and preprocessed signals, are extracted. Second, an improved distance evaluation technique is proposed, and with it, six salient feature sets are selected from the six original feature sets, respectively. Finally, the six salient feature sets are input into the multiple ANFIS combination with genetic algorithms (GAs) to identify different abnormal cases. The proposed method is applied to the fault diagnosis of rolling element bearings, and testing results show that the multiple ANFIS combination can reliably recognise different fault categories and severities, which has a better classification performance compared to the individual classifiers based on ANFIS. Moreover, the effectiveness of the proposed feature selection method based on the improved distance evaluation technique is also demonstrated by the testing results.