This paper is concerned with behavior analysis and improvement of wind turbines with Doubly Fed Induction Generator (DFIG) when using a new fractional-order control strategy during wind variations. A doubly fed induction generator, two types of variable frequency power electronic converters and two input wind waveforms are considered. A fractional-order control strategy is proposed for the wind...

We study the ergodicity of backward product of stochastic and doubly stochastic matrices by introducing the concept of absolute infinite flow property. We show that this property is necessary for ergodicity of any chain of stochastic matrices, by defining and exploring the properties of a rotational transformation for a stochastic chain. Then, we establish that the absolute infinite flow proper...

The complete convergence is investigated for moving-average processes of doubly infinite sequence of negative dependence sub-gaussian random variables with zero means, finite variances and absolutely summable coefficients. As a corollary, the rate of complete convergence is obtained under some suitable conditions on the coefficients.

The ability to morph flat sheets into complex 3D shapes is extremely useful for fast manufacturing and saving materials while also allowing volumetrically efficient storage shipment a functional use. Direct 4D printing compelling method out of as-printed 2D plates. However, most direct methods require multi-material systems involving costly machines. Moreover, works have used an open-cell desig...

In order to decrease the fluid dynamic forces of the U-bent tube with a circular section and avoid the occurrence of fluid-structure interaction problems, three-dimensional simulations of fluid flows around the tubes are carried out. In the case that the axis of the curved tube with the circular section is prevented from being normal to the direction of the flows approaching the tube, the forma...

In this paper, the problem of large pure bending deformations of membrane is considered. The membrane is a sector of torus with a closed cross-section. This membrane is called a curved tube for short. We consider the homogenous, incompressible, isotropic and hyperelastic material. The external load is a constant pressure and bending couples acting at the edges. The equilibrium equations reduce ...

Endotracheal tubes (ETTs) constitute a resistive extra load for intubated patients. The ETT pressure drop (DeltaP(ETT)) is usually described by empirical equations that are specific to one ETT only. Our laboratory previously showed that, in adult ETTs, DeltaP(ETT) is given by the Blasius formula (F. Lofaso, B. Louis, L. Brochard, A. Harf, and D. Isabey. Am. Rev. Respir. Dis. 146: 974-979, 1992)...

introduction: the exact measurement of the root canal length is of great importance in root canal therapy. although, determination of the root canal length through radiography is the most common method, recently electronic apex locators are being used to determine working length and decrease the number of radiographs. the purpose of this study was to compare the accuracy of an electronic apex l...