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Wyświetlanie 1-3 z 3
Tytuł:
Developing automatic recognition system of drill wear in standard laminated chipboard drilling process
Autorzy:
Kurek, J.
Kruk, M.
Osowski, S.
Hoser, P.
Wieczorek, G.
Jegorowa, A.
Górski, J.
Wilkowski, J.
Śmietańska, K.
Kossakowska, J.
Powiązania:
https://bibliotekanauki.pl/articles/200766.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
diagnostic expert systems
neural networks
wavelet packets
wear monitoring
diagnostyczny system ekspercki
sieci neuronowe
pakiety falkowe
monitorowanie zużycia
Opis:
The paper presents an automatic approach to recognition of the drill condition in a standard laminated chipboard drilling process. The state of the drill is classified into two classes: “useful” (sharp enough) and “useless” (worn out). The case “useless” indicates symptoms of excessive drill wear, unsatisfactory from the point of view of furniture processing quality. On the other hand the “useful” state identifies tools which are still able to drill holes acceptable due to the required processing quality. The main problem in this task is to choose an appropriate set of diagnostic features (variables), based on which the recognition of drill state (“useful” versus “useless”) can be made. The features have been generated based on 5 registered signals: feed force, cutting torque, noise, vibration and acoustic emission. Different statistical parameters describing these signals and also their Fourier and wavelet representations have been used for defining the features. Sequential feature selection is applied to detect the most class discriminative set of features. The final step of recognition is done by using three types of classifiers, including support vector machine, ensemble of decision trees and random forest. Six standard drills of 12 mm diameter with tungsten carbide tips were used in experiments. The results have confirmed good quality of the proposed diagnostic system.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2016, 64, 3; 633-640
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Joint time-frequency and wavelet analysis - an introduction
Autorzy:
Majkowski, A.
Kołodziej, M.
Rak, R. J.
Powiązania:
https://bibliotekanauki.pl/articles/220841.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
frequency analysis
time-frequency analysis
short-time Fourier transform
Gabor transform
Wigner-Ville transform
Cone-Shaped Transform
wavelet analysis
time-scale analysis
wavelet decomposition
filter banks
wavelet packets
Opis:
A traditional frequency analysis is not appropriate for observation of properties of non-stationary signals. This stems from the fact that the time resolution is not defined in the Fourier spectrum. Thus, there is a need for methods implementing joint time-frequency analysis (t/f) algorithms. Practical aspects of some representative methods of time-frequency analysis, including Short Time Fourier Transform, Gabor Transform, Wigner-Ville Transform and Cone-Shaped Transform are described in this paper. Unfortunately, there is no correlation between the width of the time-frequency window and its frequency content in the t/f analysis. This property is not valid in the case of a wavelet transform. A wavelet is a wave-like oscillation, which forms its own “wavelet window”. Compression of the wavelet narrows the window, and vice versa. Individual wavelet functions are well localized in time and simultaneously in scale (the equivalent of frequency). The wavelet analysis owes its effectiveness to the pyramid algorithm described by Mallat, which enables fast decomposition of a signal into wavelet components.
Źródło:
Metrology and Measurement Systems; 2014, 21, 4; 741-758
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Infrared devices and techniques (revision)
Autorzy:
Rogalski, A.
Chrzanowski, K.
Powiązania:
https://bibliotekanauki.pl/articles/221154.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
frequency analysis
time-frequency analysis
short-time Fourier transform
Gabor transform
Wigner-Ville transform
Cone-Shaped Transform
wavelet analysis
time-scale analysis
wavelet decomposition
filter banks
wavelet packets
Opis:
The main objective of this paper is to produce an applications-oriented review covering infrared techniques and devices. At the beginning infrared systems fundamentals are presented with emphasis on thermal emission, scene radiation and contrast, cooling techniques, and optics. Special attention is focused on night vision and thermal imaging concepts. Next section concentrates shortly on selected infrared systems and is arranged in order to increase complexity; from image intensifier systems, thermal imaging systems, to space-based systems. In this section are also described active and passive smart weapon seekers. Finally, other important infrared techniques and devices are shortly described, among them being: non-contact thermometers, radiometers, LIDAR, and infrared gas sensors.
Źródło:
Metrology and Measurement Systems; 2014, 21, 4; 565-618
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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