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Wykorzystanie metod wibracyjnych do wzorcowania systemu diagnostycznego opartego na analizie prądu zasilajacego silnik indukcyjny Application of vibration methods for calibration of diagnostic system based on motor current analysis /
No full textTyt. nagł.Bibliografia s. 205-206.Dostępny także w formie drukowanej.STRESZCZENIE: W artykule przedstawiono sposób oceny trafności diagnoz uzyskiwanych z wykorzystaniem nowej metody badawczej, opracowanej do badania uszkodzeń łożysk w silnikach indukcyjnych. Badana metoda diagnostyczna oparta jest na pomiarze i analizie prądu stojana silnika indukcyjnego. W metodzie tej, dla podwyższenia trafności diagnoz, obliczanie zarówno prędkości kątowej silnika, jak i częstotliwości sieci zasilającej jest wykonywane na podstawie tego samego widma, które dalej jest wykorzystywane do pomiaru składowych harmonicznych charakterystycznych dla uszkodzeń łożysk. Sztucznie uszkodzone łożyska poddawano kwalifikacji pod względem głębokości i rodzaju uszkodzenia, wykorzystując urządzenie pomiarowe zbudowane na podstawie opracowanej metody, również wykonując badania sprawdzonym systemem diagnostyki wibracyjnej. Niektóre wyniki badań łożysk o różnych typach i głębokości uszkodzenia oraz wnioski płynące z tych pomiarów zostały podane w niniejszym artykule. SŁOWA KLUCZOWE: prąd stojana, widmo, silniki indukcyjne, system diagnostyczny, wzorcowanie, analiza prądu, diagnostyka wibracyjna, ABSTRACT: Damage of the bearings is the most frequent cause of squirrel cage induction machines failure. In some applications the current signal is the only potential source of information about the state of the machine, including the state of its bearings. Damage of the raceway or of the rolling element is followed by additional vibrations of the rotor. These vibrations are reflected in spectral composition of the stator currents. The new measuring method and the supply current analysis were elaborated for diagnostic of the motor bearings. In this method it is possible to recognize type of bearing fault, checking the control sum for each type of possible fault. The investigation referring to real objects were performed. The investigations were carried out using motors with bearings having defects caused on purpose. Examples of diagnostic results in case of: a) faultless bearings, b) bearing with damaged outer ring are presented in Figures 2 and 3. Marks from L1 to L20 in the Figures 2 and 4 define loads from idle running (L1) to 75% of rated power (L20). The correctness of distinguishing the type of damage was investigated. The diagnosis was assumed to be correct if it conforms to the defects indicated by the standard system of the vibration diagnostics, of course, when other damages were not detected. Figures 1 and 3 show the vibration testing results. The probability of correct distinguishing the type of damage defined this way is shown in the Figure 4. The average probability of diagnostic correctness determined this way reaches 70%. The probability that the system will identify correctly at least one existing defect is more than 90%. The investigations shows, that for testing new diagnostic method it is not enough to make damage to bearing but also have other reliable diagnostic method. This method defines real state of investigated bearing. KEYWORDS: diagnostics, spectrum, current measurements, vibration measurements, induction motors
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Metoda diagnostyki łożysk na podstawie analizy przebiegów prądu i napięcia zasilającego silnik indukcyjny
No full textVariations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Elektrotechnika i Elektronika
No full textW artykule przedstawiono sposób oceny trafności diagnoz uzyskiwanych z wykorzystaniem nowej metody badawczej, opracowanej do badania uszkodzeń łożysk w silnikach indukcyjnych. Badana metoda diagnostyczna oparta jest na pomiarze i analizie prądu stojana silnika indukcyjnego. W metodzie tej, dla podwyższenia trafności diagnoz, obliczanie zarówno prędkości kątowej silnika, jak i częstotliwości sieci zasilającej jest wykonywane na podstawie tego samego widma, które dalej jest wykorzystywane do pomiaru składowych harmonicznych charakterystycznych dla uszkodzeń łożysk. Sztucznie uszkodzone łożyska poddawano kwalifikacji pod względem głębokości i rodzaju uszkodzenia, wykorzystując urządzenie pomiarowe zbudowane na podstawie opracowanej metody, również wykonując badania sprawdzonym systemem diagnostyki wibracyjnej. Niektóre wyniki badań łożysk o różnych typach i głębokości uszkodzenia oraz wnioski płynące z tych pomiarów zostały podane w niniejszym artykule.Damage of the bearings is the most frequent cause of squirrel cage induction machines failure. In some applications the current signal is the only potential source of information about the state of the machine, including the state of its bearings. Damage of the raceway or of the rolling element is followed by additional vibrations of the rotor. These vibrations are reflected in spectral composition of the stator currents. The new measuring method and the supply current analysis were elaborated for diagnostic of the motor bearings. In this method it is possible to recognize type of bearing fault, checking the control sum for each type of possible fault. The investigation referring to real objects were performed. The investigations were carried out using motors with bearings having defects caused on purpose. Examples of diagnostic results in case of: a) faultless bearings, b) bearing with damaged outer ring are presented in Figures 2 and 3. Marks from L1 to L20 in the Figures 2 and 4 define loads from idle running (L1) to 75% of rated power (L20). The correctness of distinguishing the type of damage was investigated. The diagnosis was assumed to be correct if it conforms to the defects indicated by the standard system of the vibration diagnostics, of course, when other damages were not detected. Figures 1 and 3 show the vibration testing results. The probability of correct distinguishing the type of damage defined this way is shown in the Figure 4. The average probability of diagnostic correctness determined this way reaches 70%. The probability that the system will identify correctly at least one existing defect is more than 90%. The investigations shows, that for testing new diagnostic method it is not enough to make damage to bearing but also have other reliable diagnostic method. This method defines real state of investigated bearing.wersja wydawnicz
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