H∞ controller for active magnetic bearings (AMBs) with flexible rotor system was designed in this paper. The motion equations of AMBs and flexible rotor system are built based on finite element methods (FEM). Weighting function matrices of H∞ controller for AMBs are studied for both the sensitivity and the complementary sensitivity of H∞ control theory. The simulation shows that the H∞ control ...

A detailed review and analysis of the hydrodynamic characteristics of laminar developing and fully developed flows in noncircular ducts is presented. New models are proposed, which simplify the prediction of the friction factor–Reynolds product f Re for developing and fully developed flows in most noncircular duct geometries found in heat exchanger applications. By means of scaling analysis it ...

Elastomeric bridge bearings have a history of use in the USA of close to 50 years. They are capable of carrying large vertical loads and allowing horizontal movement with low lateral force due to the extreme flexibility of the elastomeric material. They require little maintenance, have no moving parts, have good longevity and are very economical. The elastomer in bridge bearings is usually eith...

This article presents an experimental study carried out on a rotor operating two foil bearings. One of the bearings was built in way to measure temperature and deformation top bearing. The dynamic performance bearing journals is presented herein using vibration trajectories journal positions sleeve. Based these results, method for predicting distribution developed. Then, correlations between pa...

The ability to evaluate the quality of explanations is an essential part of children's intellectual growth. Explanations can be faulty in structural ways such as when they are circular. A circular explanation reiterates the question as if it were an explanation rather than providing any new information. Two experiments (N=77) examined children's preferences when faced with circular and noncircu...

A general model that predicts single-phase creeping flow pressure drop in microchannels of a noncircular cross section under slip and no-slip regimes is proposed. The model accounts for gradual variations in the cross section and relates the pressure drop to geometrical parameters of the cross section, i.e., area, perimeter, and polar moment of inertia. The accuracy of the proposed model is ass...

This paper presents a perturbation model to obtain flexural mode dispersions of noncircular fluid-filled boreholes in homogeneous elastic formations. The perturbation model is based on Hamilton's principle with a modified procedure for the reference state selection in order to handle the directional sensitivity of the flexural modes. The accuracy of the perturbation model has been confirmed by ...

Rotating machinery is the most common machinery in industry. The root of the faults in rotating machinery is often faulty rolling element bearings. This paper presents a technique using optimized artificial neural network by the Bees Algorithm for automated diagnosis of localized faults in rolling element bearings. The inputs of this technique are a number of features (maximum likelihood estima...