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Free-Standing Nanopatterned Films of Silk Sericin and Gellan Gum and the Spectroscopy Studies from Eu³⁺-Doped Films. [PDF]

ACS Omega
Torres FR, Pugina RS, de Oliveira L, Dos Santos MV, Barud HS, Ribeiro SJL, Caiut JMA.   +6 more
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Self-Excited Vibrations in Drillstrings

SPE Annual Technical Conference and Exhibition, 1987
Abstract Vibrations created by drag bits can cause premature failure of drillstring components and fracture cutters. Unfortunately, there has been no theory that adequately explains how drag bits excite drillstrings. Our paper shows that these vibrations are self excited by the interaction of drillstring, bit, and formation. Results show
C.A. Zamudio, J.L. Tlusty, D.W. Dareing
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Experimental investigation on the avoidance of self-excited vibrations

Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2007
Self-excited vibrations are observed in many technical applications. Frictional contacts are often involved in the mechanism which generates vibrations. Reasons for the excitation mechanisms are decreasing friction characteristics depending on the sliding velocity, fluctuating normal loads or different geometrical effects.
Matthias, Kröger, Marcus, Neubauer, Karl, Popp   +2 more
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Self-excited vibrations of a drillstring bit

International Applied Mechanics, 2013
The whirling vibrations of a rotating drillstring bottom-hole assembly subject to the moment of friction are analyzed qualitatively. A problem statement and solution are given. The self-excitation of vibrations is simulated. It is established that during the self-excitation of whirling vibrations, the axial line of the drill bit can slowly and rapidly ...
V. I. Gulyaev, P. Z. Lugovoi, E. I. Borshch   +2 more
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Quenching of Self-Excited Vibrations

Journal of Vibration and Acoustics, 1989
A passive vibration control system for the quenching of undesirable self-excited vibrations in mechanical systems is presented. The system is a Lanchester damper, attached to the main self-excited system; a van der Pol oscillator. A first-order perturbation solution shows that complete quenching of self-excited vibration is possible.
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Quenching of self-excited vibrations equilibrium aspects

Journal of Sound and Vibration, 1975
Abstract An analysis is presented of two types of self-excited, two-degree-of-freedom systems. The basic subsystem, in each, is governed by a Van der Pol differential equation. This subsystem is considered attached to a vibration absorber or mounted on a resilient foundation.
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Analysis Of Self-excited Longitudinal Vibration Of A Moving Tape

Journal of Sound and Vibration, 1993
Abstract Longitudinal vibration of a moving magnetic tape can be excited by frictional contact with a recording head, or with a guide that defines the path of the tape. The friction force depends on the velocity, relative to a stationary observer, of the tape element that is instantaneously located at the point of contact.
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Self-Excited Vibration of a Hydraulic Turbine

Journal of Engineering for Power, 1967
Severe vibration of a hydraulic turbine was found to be self-excited. Vibration at the natural frequency when operating at synchronous speed produced self-sustaining whirl of the shaft. Gyroscopic action of the turbine runner caused the vibration to be self-excited.
C. C. Crawford, F. O. Ruud
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On the self-excited chatter vibration in motorcycles

2023
This study is focused on the understanding of the nonlinear effects of tyre forces and chain geometry on motorcycle chatter, a self-excited oscillation arising at the rear wheel during heavy braking manoeuvres. In particular the post-bifurcation criticality is assessed, whether subcritical or supercritical, with respect to travelling speed.
Alexander Schramm, Silvio Sorrentino, Alessandro De Felice   +2 more
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Self-excited vibrations of turbomachine blading

Zeitschrift für angewandte Mathematik und Physik ZAMP, 1964
Unter Verwendung einer vereinfachten Betrachtungsweise fur die nicht-stationaren aerodynamischen Krafte wird ein Kriterium fur das Zustandekommen von selbst-erregten Schwingungen bei Axialturbinen- bzw. Axialkompressoren-Schaufeln angegeben, die entlang ihrer Hohe sowohl aerodynamisch wie auch geometrisch veranderliche Eigenschaften aufweisen.
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