Vibration mitigation

Yang G (2001) Large-scale magnetorheological fluid damper for vibration mitigation modeling, testing and control. Ph.D. Dissertation. University of Notre Dame, Notre Dame, IN, 2001... 

Conventional dynamic vibration absorbers are composed of a mass, spring, and damper. Although dynamic vibration absorbers do not have sensors or controllers, they can provide vibration mitigation similar to that of actively controlled systems with a complicated sensor, control, and actuator system. Since an absorbers mass/spring/damper forms a single degree of freedom (DOF) vibration system, it consequently has a single resonant frequency and can exhibit an amplified response at this frequency. Dynamic absorbers behave similar to a system with a sensor to detect the specific frequency and a controller to amplify the vibration. Therefore, the absorbers natural frequency should be carefully tuned to a specific frequency for which the vibration amplitude of the host structure is to be reduced. The tuned frequency usually corresponds to natural modes and harmonically excited vibrations of a system. 

Semi-Active (Adaptive-Passive) Systems Refer to an adjustable passive vibration control scheme, that is, the passive treatment can adjust itself in response to changes in the structure. For example, the stiflfiiess, damping coefficient or other variables of the passive control scheme can change automatically so that optimal vibration mitigation is induced. These variable components, also known as tunable parameters of the control system, are re-tailored via a properly developed semi-active control algorithm. Being more versatile than passive control techniques and more affordable (in terms of cost and energy consumption) than active control schemes, has made semi-active control methods very popular. 

Casciati F, Magonetle G, Marazzi F (2006) Technology of semiactive devices and applications in vibration mitigation. Wiley, Chichester. ISBN 978-0-470-02289-4... 

J Appl Mech, ASME 13, A-284 Carpineto N, Lacarbonara W, Vestroni F (2014) Hyster-etic tuned mass dampers for stmctural vibration mitigation. J Sound Vib 333(5) 1302-1318 Cartmell M, Cartmell M (1990) Introduction to linear, parametric and nonlinear vibrations. Chapman and Hall, London... 

Beeause the study of rotor dynamies and vibration analysis is eontained in numerous texts only some basie troubleshooting tables and guidelines are presented. They deseribe the most eommon peaks in a typieal vibration analysis speetrum and how these symptoms might be mitigated. 

Organic polymers and resins have also been used for zeolite binding. An early example is the use polyurethane in the formahon of vibration-resistant zeolite porous bodies for refrigerant drying [90]. Organic binders such as cellulose acetate and other cellulose-based polymers have also used to mitigate problems with binder dissolution in aqueous phase separations [91, 92]. Latex has also been used as a water-stable organic binder [93]. More recently, thermoplastic resins, such as polyethylene have also been used as binders for zeolites [94]. 

Any action in mitigating flow maldistribution must be preceded by an identification of possible reasons that may cause the performance deterioration and/or may affect mechanical characteristics of the heat exchanger. The possible reasons that affect the performance are [131,147] (1) deterioration in the heat exchanger effectiveness and pressure drop characteristics, (2) fluid freezing, as in viscous flow coolers, (3) fluid deterioration, (4) enhanced fouling, and (5) mechanical and tube vibration problems (flow-induced vibrations as a consequence of flow instabilities, wear, fretting, erosion, corrosion, and mechanical failure). 

The dissociation yield and temperature limitation (5-122) is usually stronger than the restriction related to explosion of the hydrogen-oxygen mixture (Fig. 5-55), which is mitigated because of essential vapor fraction, and hence dilution, in the produced mixture (H2-O2-H2O). The domain of vibrational and translational temperatures of water vapor, where the product stability with respect to explosion and reverse reactions can be achieved, are shown in Fig. 5-56. 

While the use of direct absorption methods has grown, indirect action spectroscopic methods continue to be widely and successfully used in the study of neutral molecular clusters. As mentioned earlier, there are two commonly used detection methods, mass spectrometers and bolometers. Because of the variety of mass-spectroscopic methods, there is an equally wide range of techniques used in neutral cluster spectroscopy. One of the oldest among these involves electron-impact mass spectrometry of a cw neutral beam combined with vibrational predissociation spectroscopy using a tunable cw or pulsed laser. The advent of continuously tunable infrared sources (such as color center lasers and LiNbOa optical parametric oscillators) allowed for detailed studies of size and composition variation in neutral clusters. However, fragmentation of the clusters within the ionizer of the mass spectrometer, severely limited the identification of particular clusters with specific masses. Isotopic methods were able to mitigate some of the limitations, but only in a few cases. 

Essentially, the problem of adiabatic leak is mitigated by the presence of constraints, whether in the form of steric hindrance, external forces, or in reduction of dimensionality (for example, simulations in torsion space). In simulations of proposed nanomachines, for example, rigid body dynamics is sometimes applied to components or substructures in order to make the entire nanostructure more rigid. All of this suggests that the prediction of failure modes in some nanomachine designs due strictly to vibrational motion is overly pessimistic. However, this does not by any means minimize concerns such as the difficulty of building desired nanostructures, chemical reactivity. 

Shock absorbing liquid (SALi) Technology -based cushions consist of small, compressible elastic capsules blended with an incompressible matrix fluid for protection from violent impacts, crash, vibrations and shock waves. It is suggested that the cushions offer four damage mitigation mechanisms in the impact energy absorption process ... 

Infrared intensities depend on the change in dipole moment of a species with the particular vibrational mode. As shown above, the calculated frequencies depend on the square-root of the eigenvalues, so errors are mitigated in calculating frequencies. On the other hand, infrared intensities depend on the square of the dipole moment derivative with respect to atomic displacements (Wilson et al. 1955). Hence, errors calculating intensities are exaggerated making accurate predictions of absorption coefficients more difficult (Kubicki et al. 1993). 

Spacer fabrics are composed of numerous spacer yams. Each spacer yam functions as an Euler s rod, which can be engineered to mitigate vibration to suit different applications (Virgin and Davis, 2003). Eigure 6.32 shows the transmissibility of three warp-knitted spacer fabrics A, B and C with a thickness of 13.31,15.14 and 19.46 mm, respectively (Liu and Hu, 2011b). The results indicate that such fabrics are very suitable for vibration isolation. The fabrics can be used to produce antivibration gloves, wheel chair cushions and so on. 

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