Many systems can be approximated as linear with coefficients that vary periodically with time. For example, an anisotropic shaft rotating at constant speed on anisotropic bearings can be modeled as periodically time varying (PTV). Similar models can be obtained for wind turbines, some mechanisms, etc... However, the vast majority of modal analysis algorithms and techniques apply only to linear ...

This paper presents an axisymmetric rotational inertia shaker for reducing the structure borne noise radiated by rotating machinery. This modular inertia shaker uses a piezostack to generate a compensating force on a rotating element by accelerating a ring shaped mass. The piezostack is controlled using an adaptive shunt circuit, which emulates the impedance of a variable inductance. The inerti...

Recently, work on rotating losses in magnetic bearings has focused mainly on the measurement of rotating losses, and on the creation of models that attempt to reproduce these results. Though there has been some success on both counts, there has been less emphasis on interpreting what these results mean in terms of practical guidelines for the design of low-loss bearings. The present work reform...

(In English) The topic of the paper deals with full spectrum evaluation. The full spectrum plays a key role in the processing of complex signals. The real part of this kind of signals is a displacement in the X-direction while the imaginary part is a displacement in the perpendicular direction, as we say in the Y-direction. A good example is a shaft rotating in the journal bearing. The shaft di...

The paper presents control system for positioning of rotating shaft ends with magnetic bearings. Problem of identification and modelling is presented as well as control algorithms. The main difficulty of the control are disturbances caused by rotation (controlled by push-pull drivers) of the shaft. Weighted minimumvariance controller has been applied and compared with built-in PD controllers. T...

For effective colonic polypectomy, the polyp has to be positioned in the 5 ± 7− o clock position in the field of view. This has traditionally been achieved by chan− ging the patient s position or by twisting the shaft of the scope, or both [1]. How− ever, rotating a heavily sedated patient is not easy, and twisting the scope exerts a force on the shaft, the position of which has to be maintaine...

By fixing two FBGs on the surface of a rotating shaft along the direction of ± 45° and using dynamic wavelength demodulation technology, we propose an optical fiber sensing system to monitor the driving torque and torsion angle of the rotating shaft. In theory, the dependence relation of the dynamic difference of central wavelengths on the torque and torsion angle of the rotating shaft has been...

This article deals with a possibility of how to determine a power dissipation in a rotating machine. It divides losses in three parts according to their origin – losses arising around the rotating disc, in bearings, and by a friction of a shaft surface due to viscosity. A precise determination of the power dissipation is important when evaluating the efficiency of the whole device. The procedur...

Laser speckle produced from a diffuse object can be used in determining the angular position of a rotating object. When the object rotates the backscattered speckle pattern, which changes continuously but repeats exactly with every revolution, is sampled by a suitably positioned photodetector. The photodetector output signal is periodic, and one period is stored in the memory as a reference. Sh...