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Tytuł:
An improved feature extraction method for rolling bearing fault diagnosis based on MEMD and PE
Autorzy:
Zhang, H.
Zhao, L.
Liu, Q.
Luo, J.
Wei, Q.
Zhou, Z.
Qu, Y.
Powiązania:
https://bibliotekanauki.pl/articles/259770.pdf
Data publikacji:
2018
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
improved feature extraction method
rolling bearing fault diagnosis
MEMD
PE
Opis:
The health condition of rolling bearing can directly influence to the efficiency and lifecycle of rotating machinery, thus monitoring and diagnosing the faults of rolling bearing is of great importance. Unfortunately, vibration signals of rolling bearing are usually overwhelmed by external noise, so the fault frequencies of rolling bearing cannot be readily obtained. In this paper, an improved feature extraction method called IMFs_PE, which combines the multivariate empirical mode decomposition with the permutation entropy, is proposed to extract fault frequencies from the noisy bearing vibration signals. First, the raw bearing vibration signals are filtered by an optimal band-pass filter determined by SK to remove the irrelative noise which is not in the same frequency band of fault frequencies. Then the filtered signals are processed by the IMFs_PE to get rid of the relative noise which is in the same frequency band of fault frequencies. Finally, a frequency domain condition indicator FFR(Fault Frequency Ratio), which measures the magnitude of fault frequencies in frequency domain, is calculated to compare the effectiveness of the feature extraction methods. The feature extraction method proposed in this paper has advantages of removing both irrelative noise and relative noise over other feature extraction methods. The effectiveness of the proposed method is validated by simulated and experimental bearing signals. And the results are shown that the proposed method outperforms other state of the art algorithms with regards to fault feature extraction of rolling bearing.
Źródło:
Polish Maritime Research; 2018, S 2; 98-106
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A comparative study of CNN, LSTM, BiLSTM, AND GRU architectures for tool wear prediction in milling processes
Autorzy:
Zegarra, Fabio C.
Vargas-Machuca, Juan
Coronado, Alberto M.
Powiązania:
https://bibliotekanauki.pl/articles/28407329.pdf
Data publikacji:
2023
Wydawca:
Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Tematy:
tool wear
feature extraction
preprocessing
recurrent neural network
Opis:
Accurately predicting machine tool wear requires models capable of capturing complex, nonlinear interactions in multivariate time series inputs. Recurrent neural networks (RNNs) are well-suited to this task, owing to their memory mechanisms and capacity to construct highly complex models. In particular, LSTM, BiLSTM, and GRU architectures have shown promise in wear prediction. This study demonstrates that RNNs can automatically extract relevant information from time series data, resulting in highly precise wear models with minimal feature engineering. Notably, this approach avoids the need for excessively large window sizes of data points during model training, which would increase model complexity and processing time. Instead, this study proposes a procedure that achieves low prediction errors with window sizes as small as 100 data points. By employing Bayesian hyperparameter optimization and two preprocessing techniques (detrend and offset), RMSE errors consistently fall below 10. A key difference in this study is the use of boxplots to provide a better representation of result variability, as opposed to solely reporting the best values. The proposed approach matches more complex state of-the-art. methods and offers a powerful tool for wear prediction in engineering applications.
Źródło:
Journal of Machine Engineering; 2023, 23, 4; 122--136
1895-7595
2391-8071
Pojawia się w:
Journal of Machine Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An application of machine learning methods to cutting tool path clustering and rul estimation in machining
Autorzy:
Zegarra, Fabio C.
Vargas-Machuca, Juan
Roman-Gonzalez, Avid
Coronado, Alberto M.
Powiązania:
https://bibliotekanauki.pl/articles/28407324.pdf
Data publikacji:
2023
Wydawca:
Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Tematy:
feature extraction
k-means clustering
time series
unsupervised learning
Opis:
Machine learning has been widely used in manufacturing, leading to significant advances in diverse problems, including the prediction of wear and remaining useful life (RUL) of machine tools. However, the data used in many cases correspond to simple and stable processes that differ from practical applications. In this work, a novel dataset consisting of eight cutting tools with complex tool paths is used. The time series of the tool paths, corresponding to the three-dimensional position of the cutting tool, are grouped according to their shape. Three unsupervised clustering techniques are applied, resulting in the identification of DBA-k-means as the most appropriate technique for this case. The clustering process helps to identify training and testing data with similar tool paths, which is then applied to build a simple two-feature prediction model with the same level of precision for RUL prediction as a more complex four-feature prediction model. This work demonstrates that by properly selecting the methodology and number of clusters, tool paths can be effectively classified, which can later be used in prediction problems in more complex settings.
Źródło:
Journal of Machine Engineering; 2023, 23, 4; 5--17
1895-7595
2391-8071
Pojawia się w:
Journal of Machine Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparative analysis of selected classifiers in posterior cruciate ligaments computer aided diagnosis
Autorzy:
Zarychta, P.
Badura, P.
Pietka, E.
Powiązania:
https://bibliotekanauki.pl/articles/200544.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
posterior cruciate ligament
computer aided diagnosis
feature extraction
classification
soft computing
więzadło krzyżowe tylne
diagnostyka wspierana komputerowo
klasyfikacja
obliczenia miękkie
Opis:
A study on computer aided diagnosis of posterior cruciate ligaments is presented in this paper. The diagnosis relies on T1-weighted magnetic resonance imaging. During the image analysis stage, the ligament region is automatically detected, localized, and extracted using fuzzy segmentation methods. Eight geometric features are defined for the ligament object. With a clinical reference database containing 107 cases of both healthy and pathological cases, a Fisher linear discriminant is used to select 4 most distinctive features. At the classification stage we employ five different soft computing classifiers to evaluate the feature vector suitability for the computerized ligament diagnosis. Among the classifiers we introduce and specify the particle swarm optimization based Sugeno-type fuzzy inference system and compare its performance to other established classification systems. The classification accuracy metrics: sensitivity, specificity, and Dice index all exceed 90% for each classifier under consideration, indicating high level of the proposed feature vector relevance in the computer aided ligaments diagnosis.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2017, 65, 1; 63-70
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Classification of the indoor environment of a mobile robot using principal component analysis
Autorzy:
Yaqub, T.
Katupitya, J.
Powiązania:
https://bibliotekanauki.pl/articles/384275.pdf
Data publikacji:
2008
Wydawca:
Sieć Badawcza Łukasiewicz - Przemysłowy Instytut Automatyki i Pomiarów
Tematy:
mobile robot environment
PCA
classification
feature extraction
training data
bootstrap method
Opis:
Large indoor environments of a mobile robot usually consist of different types of areas connected together. The structure of a corridor differs from a room, a main hall or laboratory. A method for online classification of these areas using a laser scanner is presented in this paper. This classification can reduce the search space of localization module to a great extent making the navigation system efficient. The intention was to make the classification of a sensor observation in a fast and real-time fashion and immediately on its arrival in the sensor frame. Our approach combines both the feature based and statistical approaches. We extract some vital features of lines and corners with attributes such as average length of lines and distance between corners from the raw laser data and classify the observation based on these features. Bootstrap method is used to get a robust correlation of features from training data and finally Principal Component Analysis (PCA) is used to model the environment. In PCA, the underlying assumption is that data is coming from a multivariate normal distribution. The use of bootstrap method makes it possible to use the observations data set which set, which is not necessarily normally distributed. This technique lifts up the normality assumption and reduces the computational cost further as compared to the PCA techniques based on raw sensor data and can be easily implemented in moderately complex indoor environment. The knowledge of the environment can also be up-dated in an adaptive fashion. Results of experimentation in a simulated hospital building under varying environmental conditions using a real-time robotic software Player/Stage are shown.
Źródło:
Journal of Automation Mobile Robotics and Intelligent Systems; 2008, 2, 2; 44-53
1897-8649
2080-2145
Pojawia się w:
Journal of Automation Mobile Robotics and Intelligent Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pattern Recognition Methods for Detecting Voltage Sag Disturbances and Electromagnetic Interference in Smart Grids
Autorzy:
Yalcin, T.
Ozdemir, M.
Powiązania:
https://bibliotekanauki.pl/articles/136160.pdf
Data publikacji:
2016
Wydawca:
EEEIC International Barbara Leonowicz Szabłowska
Tematy:
C4.5 decision trees
electromagnetic interference
feature extraction
hilbert huang transform
power quality disturbance
smart grids
support vector machines
Opis:
Identification of system disturbances, detection of them guarantees smart grids power quality (PQ) system reliability and provides long lasting life of the power system. The key goal of this study is to find the best accuracy of identification algorithm for non-stationary, non-linear power quality disturbances such as voltage sag, electromagnetic interference in smart grids. PQube, power quality and energy monitor, was used to acquire these distortions. Ensemble Empirical Mode Decomposition is used for electromagnetic interference reduction with first intrinsic mode function. Hilbert Huang Transform is used for generating instantaneous amplitude and instantaneous frequency feature of real time voltage sag power signal. Outputs of Hilbert Huang Transform is intrinsic mode functions (IMFs), instantaneous frequency (IF), and instantaneous amplitude (IA). Characteristic features are obtained from first IMFs, IF, and IA. The six features—, the mean, standard deviation,skewness, kurtosis of both IF and IA are then calculated. These features are normalized along with the inputs classifiers. The proposed power system monitoring system is able to detect power system voltage sag disturbances and capable of recognize electromagnetic interference component. In this study based on experimental studies, Hilbert Huang Transform based pattern recognition technique was used to investigate power signal to diagnose voltage sag and in power grid. Support Vector Machines and C4.5 Decision Tree were operated and their achievements were matched for precision and CPU timing. According to the analysis, decision tree algorithm without dimensionality reduction produces the best solution.
Źródło:
Transactions on Environment and Electrical Engineering; 2016, 1, 3; 86-93
2450-5730
Pojawia się w:
Transactions on Environment and Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Semantic Segmentation of Diseases in Mushrooms using Enhanced Random Forest
Autorzy:
Yacharam, Rakesh Kumar
Sekhar, Dr. V. Chandra
Powiązania:
https://bibliotekanauki.pl/articles/31339414.pdf
Data publikacji:
2023
Wydawca:
Szkoła Główna Gospodarstwa Wiejskiego w Warszawie. Instytut Informatyki Technicznej
Tematy:
mushroom diseases
semantic segmentation
computer aided
Machine Learning
significant feature extraction
Random Forest classifier
Opis:
Mushrooms are a rich source of antioxidants and nutritional values. Edible mushrooms, however, are susceptible to various diseases such as dry bubble, wet bubble, cobweb, bacterial blotches, and mites. Farmers face significant production losses due to these diseases affecting mushrooms. The manual detection of these diseases relies on expertise, knowledge of diseases, and human effort. Therefore, there is a need for computer-aided methods, which serve as optimal substitutes for detecting and segmenting diseases. In this paper, we propose a semantic segmentation approach based on the Random Forest machine learning technique for the detection and segmentation of mushroom diseases. Our focus lies in extracting a combination of different features, including Gabor, Bouda, Kayyali, Gaussian, Canny edge, Roberts, Sobel, Scharr, Prewitt, Median, and Variance. We employ constant mean-variance thresholding and the Pearson correlation coefficient to extract significant features, aiming to enhance computational speed and reduce complexity in training the Random Forest classifier. Our results indicate that semantic segmentation based on Random Forest outperforms other methods such as Support Vector Machine (SVM), Naïve Bayes, K-means, and Region of Interest in terms of accuracy. Additionally, it exhibits superior precision, recall, and F1 score compared to SVM. It is worth noting that deep learning-based semantic segmentation methods were not considered due to the limited availability of diseased mushroom images.
Źródło:
Machine Graphics & Vision; 2023, 32, 2; 129-146
1230-0535
2720-250X
Pojawia się w:
Machine Graphics & Vision
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research on ship trajectory extraction based on multiattribute DBSCAN optimisation algorithm
Autorzy:
Xu, Xiaofeng
Cui, Deqaing
Li, Yun
Xiao, Yingjie
Powiązania:
https://bibliotekanauki.pl/articles/1551877.pdf
Data publikacji:
2021
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
clustering algorithm
abnormal route
DBSCAN
feature trajectory extraction
fitting analysis
Opis:
With the vigorous development of maritime traffic, the importance of maritime navigation safety is increasing day by day. Ship trajectory extraction and analysis play an important role in ensuring navigation safety. At present, the DBSCAN (density-based spatial clustering of applications with noise) algorithm is the most common method in the research of ship trajectory extraction, but it has shortcomings such as missing ship trajectories in the process of trajectory division. The improved multi-attribute DBSCAN algorithm avoids trajectory division and greatly reduces the probability of missing sub-trajectories. By introducing the position, speed and heading of the ship track point, dividing the complex water area and vectorising the ship track, the function of guaranteeing the track integrity can be achieved and the ship clustering effect can be better realised. The result shows that the cluster fitting effect reaches up to 99.83%, which proves that the multi-attribute DBSCAN algorithm and cluster analysis algorithm have higher reliability and provide better theoretical guidance for the analysis of ship abnormal behaviour.
Źródło:
Polish Maritime Research; 2021, 1; 136-148
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A diagnostic algorithm diagnosing the failure of railway signal equipment
Autorzy:
Wu, Yongcheng
Cao, Dejin
Powiązania:
https://bibliotekanauki.pl/articles/1955227.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN
Tematy:
failure diagnosis
railway signal equipment
denoising
feature extraction
diagnostyka uszkodzeń
sygnalizacja kolejowa
odszumianie
ekstrakcja cech
Opis:
Failure of railway signal equipment can cause an impact on its normal operation, and it is necessary to make a timely diagnosis of the failure. In this study, the data of a railway bureau from 2016 to 2020 were studied as an example. Firstly, denoising and feature extraction were performed on the data; then the Adaptive Comprehensive Oversampling (ADASYN) method was used to synthesize minority class samples; finally, three algorithms, back-propagation neural network (BPNN), support vector machine (SVM) and C4.5 algorithms, were used for failure diagnosis. It was found that the three algorithms performed poorly in diagnosing the original data but performed significantly better in diagnosing the synthesized samples, among which the BPNN algorithm had the best performance. The average precision, recall rate and F1 score of the BPNN algorithm were 0.94, 0.92 and 0.93, respectively. The results verify the effectiveness of the BPNN algorithm for failure diagnosis, and the algorithm can be further promoted and applied in practice.
Źródło:
Diagnostyka; 2021, 22, 4; 33-38
1641-6414
2449-5220
Pojawia się w:
Diagnostyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new approach to image-based recommender systems with the application of heatmaps maps
Autorzy:
Woldan, Piotr
Duda, Piotr
Cader, Andrzej
Laktionov, Ivan
Powiązania:
https://bibliotekanauki.pl/articles/2201330.pdf
Data publikacji:
2023
Wydawca:
Społeczna Akademia Nauk w Łodzi. Polskie Towarzystwo Sieci Neuronowych
Tematy:
feature extraction
recommender system
heatmap
Opis:
One of the fundamental issues of modern society is access to interesting and useful content. As the amount of available content increases, this task becomes more and more challenging. Our needs are not always formulated in words; sometimes we have to use complex data types like images. In this paper, we consider the three approaches to creating recommender systems based on image data. The proposed systems are evaluated on a real-world dataset. Two case studies are presented. The first one presents the case of an item with many similar objects in a database, and the second one with only a few similar items
Źródło:
Journal of Artificial Intelligence and Soft Computing Research; 2023, 13, 2; 63--72
2083-2567
2449-6499
Pojawia się w:
Journal of Artificial Intelligence and Soft Computing Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Fast Method of Feature Extraction for Lowering Vehicle Pass-By Noise Based on Nonnegative Tucker3 Decomposition
Autorzy:
Wang, H.
Cheng, G.
Deng, G.
Li, X.
Li, H.
Huang, Y.
Powiązania:
https://bibliotekanauki.pl/articles/177883.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
vehicle pass-by noise
NTD
feature extraction
sound pressure level
Opis:
Usually, the judgement of one type fault of vehicle pass-by noise is difficult for engineers, especially when some significant features are disturbed by other interference noise, such as the squealing noise is almost simultaneous with the whistle in the exhaust system. In order to cope with this problem, a new method, with the antinoise ability of the algorithm on the condition by which the features are entangled, is developed to extract clear features for the fault analysis. In the proposed method, the nonnegative Tucker3 decomposition (NTD) with fast updating algorithm, signed as NTD_FUP, can find out the natural frequency of the parts/components from the exhaust system. Not only does the NTD_FUP extract clear features from the confused noise, but also it is superior to the traditional methods in practice. Then, an aluminium-foil alloy material, which is used for the heat shield for its lower noise radiation, replaces the aluminium alloy alone. Extensive experiments show that the sound pressure level of the vehicle pass-by noise is reduced 0.9 dB(A) by the improved heat shield, which is also considered as a more lightweight design for the exhaust system of an automobile.
Źródło:
Archives of Acoustics; 2017, 42, 4; 619-629
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research on bispectrum analysis of secondary feature for vehicle exterior noise based on nonnegative tucker3 decomposition
Badania nad analizą bispektrum cech drugorzędnych hałasu zewnętrznego pojazdów w oparciu o nieujemną dekompozycję Tuckera3
Autorzy:
Wang, H.
Deng, G.
Li, Q.
Kang, Q.
Powiązania:
https://bibliotekanauki.pl/articles/301586.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
Tematy:
feature extraction
vehicle exterior noise
NTD
updating algorithm
ekstrakcja cech
hałas zewnętrzny pojazdu
algorytm aktualizacyjny
Opis:
Nowadays, analysis of external vehicle noise has become more and more difficult for NVH (noise vibration and harshness) engineer to find out the fault among the exhaust system when some significant features are masked by the jamming signals, especially in the case of the vibration noise associating to the bodywork. New method is necessary to be explored and applied to decompose a high-order tensor and extract the useful features (also known as secondary features in this paper). Nonnegative Tucker3 decomposition (NTD) is proposed and applied into secondary feature extraction for its high efficiency of decomposition and well property of physical architecture, which serves as fault diagnosis of exhaust system for an automobile car. Furthermore, updating algorithm conjugating with Newton-Gaussian gradient decent is utilized to solve the problem of overfitting, which occurs abnormally on traditional iterative method of NTD. Extensive experimen results show the bispectrum of secondary features can not only exceedingly interpret the state of vehicle exterior noise, but also be benefit to observe the abnormal frequency of some important features masked before. Meanwhile, the overwhelming performance of NTD algorithm is verified more effective under the same condition, comparing with other traditional methods both at the deviation of successive relative error and the computation time.
Obecnie inżynierowie NVH (zajmujący się problematyką hałasu, drgań i uciążliwości akustycznych) napotykają na coraz większe trudności przy analizie hałasu zewnętrznego pojazdów wynikające z faktu, że istotne cechy związane z nieprawidłowościami układu wydechowego są maskowane przez sygnały zakłócające, szczególnie hałas wibracyjny związany z pracą nadwozia. Niezbędna jest zatem nowa metoda, która pozwoli rozkładać tensory wysokiego rzędu i wyodrębniać przydatne cechy (zwane w tym artykule także cechami drugorzędnymi). Do ekstrakcji cech drugorzędnych wykorzystano w prezentowanej pracy metodę nieujemnej faktoryzacji tensorów znaną także jako nieujemna dekompozycja Tuckera 3 (NTD) , która cechuje się wysoką efektywnością dekompozycji i może być wykorzystywana w diagnostyce uszkodzeń układu wydechowego samochodów. Problem nadmiernego dopasowania, który występuje w tradycyjnej metodzie iteracyjnej NTD rozwiązano przy pomocy algorytmu aktualizacyjnego sprzężonego z gradientem prostym Newtona-Gaussa. Wyniki doświadczeń pokazują, że bispektrum cech drugorzędnych nie tylko pozwala doskonale interpretować stan hałasu zewnętrznego pojazdu, ale również umożliwia wykrywanie wcześniej maskowanych nieprawidłowych częstotliwości odpowiadających niektórym ważnym cechom. Badania potwierdzają, że algorytmu NTD jest bardziej efektywny, w tych samych warunkach, w porównaniu z innymi tradycyjnymi metodami zarówno w zakresie odchyleń błędu względnego jak i czasu obliczeń.
Źródło:
Eksploatacja i Niezawodność; 2016, 18, 2; 291-298
1507-2711
Pojawia się w:
Eksploatacja i Niezawodność
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Classification Method Related to Respiratory Disorder Events Based on Acoustical Analysis of Snoring
Autorzy:
Wang, Can
Peng, Jianxin
Zhang, Xiaowen
Powiązania:
https://bibliotekanauki.pl/articles/176601.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
acoustical analysis
feature extraction
support vector machine
snoring sound
Opis:
Acoustical analysis of snoring provides a new approach for the diagnosis of obstructive sleep apnea hypopnea syndrome (OSAHS). A classification method is presented based on respiratory disorder events to predict the apnea-hypopnea index (AHI) of OSAHS patients. The acoustical features of snoring were extracted from a full night’s recording of 6 OSAHS patients, and regular snoring sounds and snoring sounds related to respiratory disorder events were classified using a support vector machine (SVM) method. The mean recognition rate for simple snoring sounds and snoring sounds related to respiratory disorder events is more than 91.14% by using the grid search, a genetic algorithm and particle swarm optimization methods. The predicted AHI from the present study has a high correlation with the AHI from polysomnography and the correlation coefficient is 0.976. These results demonstrate that the proposed method can classify the snoring sounds of OSAHS patients and can be used to provide guidance for diagnosis of OSAHS.
Źródło:
Archives of Acoustics; 2020, 45, 1; 141-151
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Klasyfikacja stanów przedkrytycznych
Classification of pre-critical states
Autorzy:
Topczewska, M.
Frischmuth, K.
Powiązania:
https://bibliotekanauki.pl/articles/154431.pdf
Data publikacji:
2012
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
klasyfikacja
ekstrakcja cech
classification
feature extraction
Opis:
Praca zawiera przykład klasyfikacji danych rzeczywistych opisujących sygnały niekrytyczne, przedkrytyczne i krytyczne. Celem jest rozpoznanie stanów niebezpiecznych tak wcześnie jak to możliwe. Ze względu na brak separowalności liniowej danych w celu separacji klas użyto klasyfikacji hierarchicznej z cięciami za pomocą klasyfikatorów liniowych oraz z podejściem one-versus-rest z wyróżnioną klasą sygnałów bezpiecznych. W wyniku ośmiu cięć uzyskano ostateczny podział przestrzeni skutkujący odseparowaniem klasy sygnałów bezpiecznych od podejrzanych, tj. przedkrytycznych i krytycznych oraz dający najmniejszą liczbę błędnie sklasyfikowanych obiektów z klasy sygnałów niekrytycznych.
The paper presents an application of classification methods to time-continuous signals (1). Signals with values that exceed a certain critical maximum are called dangerous or critical, otherwise we speak about normal or routine operation of the system under consideration, Fig. 1. The problem is to recognize pre-critical states, i.e. states preceding the actual dangerous ones, and that as early as possible. False negative classifications may have very serious consequences, while false positive verdicts cause expensive but unnecessary counter-measures. As pre-processing, the input signals are characterized by a number of features, which form sequences of vector data, indexed by the cycle number (2). In a first stage, suspicious feature vectors are selected, from which in a second sweep unlikely candidates are removed. The focus of the present paper is this second stage, i.e. the distinction between actual pre-critical and the harmless routine states among the suspicious states, indicated in the first stage by a certain preliminary test. The choice of features and the logic behind the preliminary test are beyond our present scope. Let it suffice to say that the first step is a combination of Principal Component Analysis and some statistical test, and that it is very effective but unspecific in the application at hand.For the real-world data we used to develop the method, it turned out that the obtained feature vectors were linearly non-separable. For that reason a hierarchical approach was applied, where in several steps linear cuts (4,5) of the one-versus-rest type were performed in order to single out the true pre-critical states. For the example under consideration, in eight iterations separation between pre-critical and non-pre-critical ones was achieved. We succeeded to keep the number of wrong negatives at zero while reducing the number of wrong positives to a fraction of the starting value, established by the preliminary test, Fig. 3, 4, 5. The final sensitivity, for the given data set, is 100%, and the achieved specificity is at 93.15%. Numerical experiments, using nonlinear classifiers on much larger data sets, are under way. The present aim is to find an optimal set of features and a one-step criterion which further improves the quality of the classification.
Źródło:
Pomiary Automatyka Kontrola; 2012, R. 58, nr 10, 10; 872-875
0032-4140
Pojawia się w:
Pomiary Automatyka Kontrola
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Additional data preprocessing and feature extraction in automatic classification of heartbeats
Dodatkowe przetwarzanie wstępne i ekstrakcja cech w procesie automatycznej klasyfikacji rytmu serca
Autorzy:
Tadejko, P.
Powiązania:
https://bibliotekanauki.pl/articles/341075.pdf
Data publikacji:
2007
Wydawca:
Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:
ECG
przetwarzanie wstępne
morfologia matematyczna
filtrowanie ECG
ekstrakcja cech
klasyfikacja rytmu serca
preprocessing
mathematical morphology
ECG filtering
wavelet approximation
feature extraction
heartbeat classification
Opis:
The paper presents the classification performance of an automatic classifier of the electrocardiogram (ECG) for the detection abnormal beats with new concept of feature extraction stage. Feature sets were based on ECG morphology and RR-intervals. This paper compares two strategies for classification of annotated QRS complexes: based on original ECG morphology features and proposed new approach - based on preprocessed ECG morphology features. The mathematical morphology filtering and wavelet trans-form is used for the preprocessing of ECG signal. Within this framework, the problem of choosing an appropriate structuring element in mathematical morphology filtering in signal processing was studied. Configuration adopted a Kohonen self-organizing maps (SOM) and Support Vector Machine (SVM) for analysis of signal features and clustering. In this study, a classifiers was developed with LVQ and SVM algorithms using the data from the records recommended by ANSI/AAMI EC57 standard. The performance of the algorithm is evaluated on the MIT-BIH Arrhythmia Database following the AAMI recommendations. Using this method the results of identify beats either as normal or arrhythmias was improved.
Artykuł prezentuje nowe podejście do problemu klasyfikacji zapisów ECG w celu detekcji zachowań chorobowych. Podstawą koncepcji fazy ekstrakcji cech jest proces przetwarzania wstępnego sygnału ECG z wykorzystaniem morfologii matematycznej oraz innych transformacji. Morfologia matematyczna bazując na teorii zbiorów, pozwala zmienić charakterystyczne elementy sygnału. Dwie podstawowe operacje: dylatacja i erozja pozwalają na uwydatnienie lub redukcję wielkości i kształtu określonych elementów w danych. Parametry charakterystyki zapisów ECG stanowią bazę dla wektora cech. Do klasyfikacji przebiegów ECG w pracy wykorzystano samoorganizujące się mapy (SOM) Kohonena z klasyfikatorem LVQ oraz algorytm Support Vector Machines (SVM). Eksperymenty przeprowadzono klasyfikując sygnały pomiędzy trzynaście kategorii rekomendowanych przez standard ANSI/AAMI EC57, to jest: prawidłowy rytm serca i 12 arytmii. Zaproponowany w artykule algorytm opiera się na wykorzystaniu elementarnych operacji morfologii matematycznej i ich kombinacji. Ocenę wyników eksperymentów przeprowadzono na sygnałach z bazy MIT/BIH. Na tej podstawie zaproponowano wyjściową architekturę bloku filtrów morfologicznych dla celów ekstrakcji cech oraz unifikacji wejściowego sygnału ECG jako danych wejściowych do budowy wektora cech.
Źródło:
Zeszyty Naukowe Politechniki Białostockiej. Informatyka; 2007, 2; 155-173
1644-0331
Pojawia się w:
Zeszyty Naukowe Politechniki Białostockiej. Informatyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 69

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