We report on the observation of second-harmonic conical waves generated in a novel geometry of the transverse excitation of an annular periodically poled nonlinear photonic structure by a fundamental Gaussian beam. We show that the conical beams are formed as a result of the higher-order nonlinear Bragg diffraction involving two parametric processes in which an ordinary fundamental wave is conv...

We have observed phase singularities due to vortex excitation in Bose-Einstein condensates. Vortices were created by moving a laser beam through a condensate. They were observed as dislocations in the interference fringes formed by the stirred condensate and a second unperturbed condensate. The velocity dependence for vortex excitation and the time scale for re-establishing a uniform phase acro...

In this article, a 3D dynamic model and nonlinear free vibration analysis of uniform beam attached to rigid hub rotating at two adjacent rotary joints are presented. The is performed by considering the effects steady-state axial deformation, Coriolis terms, geometric nonlinearity means von Karman’s strain–displacement relations. coupled axial, chordwise, flapwise equations motion derived from H...

In this study; free vibration analysis of a uniform, rotating, cantilever Timoshenko beam featuring coupling between flapwise bending and torsional vibrations is performed. At the beginning of the study, kinetic and potential energy expressions of a rotating Timoshenko beam having single cross-sectional symmetry are derived by using several explanatory tables and figures. In the following secti...

Since the rotor blade system of an horizontal axis wind turbine is responsible for converting energy into mechanical, which turns electrical and predicting its dynamic behavior vital importance. In that sense, this paper deals with performing a modal analysis belonging to DTU 10-MW reference by using modified Myklestad’s method. The model was built on two different keystones, as follows: first,...

We have conducted a series of experiments on 30:1 scale wind turbine blade and observed coupled-mode flutter. This observation validates the theoretical studies that predict larger blades are susceptible to To conduct these experiments, we built scaled-down model 61-meter NREL 5 MW blade. The was approximately 2 meters long such ratios between its first torsional natural frequency flapwise freq...

Abstract Active Trailing Edge Flap Systems (ATEFS) have shown promising results on reducing Wind Turbine fatigue and ultimate loads increasing the Annual Energy Production. However, current lack of field validation creates uncertainty in fidelity level accuracy engineering models used for aeroelastic modeling active flaps, these systems actual load reduction capabilities are question. This arti...

This paper reports on the analysis of the signals sent by accelerometers fixed on the axles of a vehicle which passes over a bridge. The length of the bridge is divided into some parts and the transmissibility measurement is applied to the signals recorded by two following instrumented axles. As the transmissibility procedure is performed on the divided signals, the method is called Short Time ...

The suppression of the regenerative chatter phenomenon in turning process via the variation of the frequency and amplitude of the spindle motor excitation is carried out in this research. A programmable inverter is employed for variable periodic excitation of the spindle motor. A set of turning experiments is designed and performed on a number of conical work pieces both in constant spindle spe...