461 research outputs found

    Auxiliary State Variables for Rotor Crack Detection

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    In the present study, a new model-based method for rotor crack detection and crack location is proposed. The finiteelement model of the rotor-bearing system accounts for the breathing mechanism of the crack. The model of the rotor system is augmented with an auxiliary single-degree-of-freedom oscillator. The observer is designed and the estimates of its two auxiliary state variables are proposed as crack indicators. The crack location along the shaft is determined by designing a set of observers, which calculate the values of these indicators for different possible crack locations along the shaft. The proposed method is validated numerically and the results prove its capability to detect and locate the crack. Further study will include experimental and numerical investigations to make the approach more robust

    Controlled Deflection Approach for Rotor Crack Detection

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    Atransverse shaft crack is a serious malfunction that can occurdue to cyclic loading, creep, stress corrosion, and other mechanismsto which rotating machines are subjected. Though studied for manyyears, the problems of early crack detection and warning arestill in the limelight of many researchers. This is dueto the fact that the crack has subtle influence onthe dynamic response of the machine and still there areno widely accepted, reliable methods of its early detection. Thispaper presents a new approach to these problems. The methodutilizes the coupling mechanism between the bending and torsional vibrationsof the cracked, nonrotating shaft. By applying an external lateralforce of constant amplitude, a small shaft deflection is induced.Simultaneously, a harmonic torque is applied to the shaft inducingits torsional vibrations. By changing the angular position of thelateral force application, the position of the deflection also changesopening or closing of the crack. This changes the waythe bending and torsional vibrations are being coupled. By studyingthe coupled lateral vibration response for each angular position ofthe lateral force one can assess the possible presence ofthe crack. The approach is demonstrated with a numerical modelof a rotor. The model is based on the rigidfinite element method (RFE), which has previously been successfully appliedfor the dynamic analysis of many complicated, mechanical structures. TheRFE method is extended and adopted for the modeling ofthe cracked shafts. An original concept of crack modeling utilizingthe RFE method is presented. The crack is modeled asa set of spring-damping elements (SDEs) of variable stiffness connectingtwo sections of the shaft. By calculating the axial deformationsof the SDEs, the opening/closing mechanism of the crack isintroduced. The results of numerical analysis demonstrate the potential ofthe suggested approach for effective shaft crack detection

    Same-sign W pair production as a probe of double parton scattering at the LHC

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    We study the production of same-sign W boson pairs at the LHC in double parton interactions. Compared with simple factorised double parton distributions (dPDFs), we show that the recently developed dPDFs, GS09, lead to non-trivial kinematic correlations between the W bosons. A numerical study of the prospects for observing this process using same-sign dilepton signatures, including same-sign WWjj, di-boson and heavy flavour backgrounds, at 14 TeV centre-of-mass energy is then performed. It is shown that a small excess of same-sign dilepton events from double parton scattering over a background dominated by single scattering WZ(gamma*) production could be observed at the LHC.Comment: 14 pages, 8 figures. Added references, slight changes in the text

    Direct Democracy Institutions in Authoritarian States in Pre-War Europe

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    The aim of the paper is to present direct democracy institutions provided for in the constitutions of authoritarian states in pre-war Europe, or applied in practice by authoritarian states. Such institutions were included in the constitutions created by authoritarian governments in Lithuania (1928), Austria (1934) and Estonia (1937) or used in practice: in Portugal (1933), Greece (1935), Estonia (1936) and Romania (1938). Two authoritarian states included in their constitutions provisions on opinion–giving and law–giving referenda. These were Austria (1934) and Estonia (1937). However, these provisions had never been applied in practice. Seeking the genesis of the phenomenon described in the paper, it is necessary to go back to the start of the 19th century and point to the reign of Napoleon Bonaparte, initially as First Consul and then Emperor of France. The nature of these republican and subsequently imperial plebiscytes was clearly anti-parlamentary and [email protected] WarszawskiBonarek J., Czekalski T., Sprawski S., Turlej S., Historia Grecji, Kraków 2005.Baszkiewicz J., Powszechna historia ustrojów państwowych, wyd. 2, Gdańsk 2001.Demel J., Historia Rumunii, wyd. 2 popr. i uzup., Warszawa 1986.Gembarzewski L., Nowe konstytucje. Konstytucja austriacka, „Biuletyn Urzędniczy” 1934, nr 5-6 i nr 7-8.Gembarzewski L., Nowe konstytucje. Konstytucja Estonii, „Biuletyn Urzędniczy” 1938, nr 7-8.Gembarzewski L., Nowe konstytucje. Konstytucja litewska, „Biuletyn Urzędniczy” 1938, nr 5-6.Gembarzewski L., Nowe konstytucje. Konstytucja Portugalii, „Biuletyn Urzędniczy” 1935, nr 5-6.Hermano Soraiva J., Krótka historia Portugalii, Kraków 2000.Konstytucja Litwy, red. L. Garlicki, Warszawa 2006.Konstytucje Finlandii, Włoch, Niemieckiej Republiki Federalnej i Francji, red. A. Burda, M. Rybicki, Wrocław 1971.Kozeński J., Historia Austrii 1918-1968, Poznań 1970.Makowski J., Nowe konstytucje, Warszawa 1925.Miller A., Nowa konstytucja państwa litewskiego, Warszawa 1930.Ochmański J., Historia Litwy, Warszawa 1982.Oliveira Marques A. de, Historia Portugalii, Warszawa 1987.Romer M., Organizacja władzy politycznej w rozwoju konstytucyjnym Republiki Litewskiej, Wydawnictwa Grup Polskich Porozumień Prawniczych z Zagranicą, Warszawa 1939, zeszyt 4.Tanty M., Bałkany w XX wieku Dzieje polityczne, Warszawa 2003.Uluots J., Rozwój konstytucyjny Estonii ze specjalnym uwzględnieniem roli prezydenta republiki [w:] Państwa bałtyckie, Wydawnictwa Grup Polskich Porozumień Prawniczych z Zagranicą, Warszawa 1939, z. 4.Wereszycki H., Historia Austrii, Wrocław 1986.127-14
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