Search results for "Pitch"

Wind Turbine Mechanical Characteristics and Grid Parameters Influence on the Transient Voltage Stability of a Fixed Speed Wind Turbine

2008

This paper describes the effect of wind turbine mechanical characteristic of construction and grid parameters on the transient voltage stability of a fixed speed wind turbine (FSWT) connected to a simple grid. The model of FSWT has been developed in Matlab/Simulink. Using this model, a three-phase fault is applied close to the wind turbine (WT) and cleared by disconnecting the faulted line. The effects of mechanical construction of WT and of grid parameters on the voltage stability of this simple case are evaluated and discussed. The considered parameters are the inertia coefficient of the WT, the short-circuit power at the connection bus, the hub-generator resonant frequency, the wind spee…

Effects of Electrical Parameters of Induction Generator on the Transient Voltage Stability of a Fixed Speed Wind Turbine

2008

This paper describes the effect of electrical parameters of the induction generator on the transient voltage stability of a fixed speed wind turbine connected to a simple grid; the dynamic behavior of a wind turbine connected to the grid is examined. The model of the fixed speed wind turbine has been developed in the simulation tool Matlab/Simulink. Itpsilas composed by the induction generator, the shaft system, the aerodynamic model of the wind turbine rotor and the pitch control system. Using this model, a three-phases fault is applied close to the wind turbine and cleared by disconnecting the faulted line. The effect of different electrical parameters of the induction generator on the vo…

OVERVIEW OF ANALYTICAL PROCEDURES FOR FATTY AND RESIN ACIDS IN THE PAPERMAKING PROCESS

2012

This review describes the role of wood extractives, especially fatty and resin acids, in papermaking, as well as the importance of their removal from process waters. One of the main aims is also to illustrate versatile analysis methods for this purpose and highlight recent developments in corresponding applications. Most of the current methods require time-consuming and laborious sample pretreatment procedures prior to gas chromatography coupled either with flame ionization or mass selective detection. However, some faster, even online techniques with minimum sample pretreatment, are also available, mainly including high performance liquid chromatography coupled with mass spectrometry. The …

''Isokinetic intervention in microtraumatic shoulder instability: an update''

2012

Gremeaux, V. | Croisier, J. L. | Forthomme, B.; International audience; ''Aim. Aim of the present study was to carry out a critical analysis of the use of isokinetic dynamometers for evaluation and rehabilitation in microtraumatic shoulder instability. Methods. A non-systematic literature review was conducted on Medline using the following key words: "isokinetics", "shoulder instability", "evaluation", "rehabilitation". We also analyzed the related articles, and compiled a database of expert opinion. Results. Despite a lack of consensus on testing modalities, lateral and medial rotator muscle strength can be safely and reliably assessed on isokinetic devices in subjects presenting with micr…

Modified post-bifurcation dynamics and routes to chaos from double-Hopf bifurcations in a hyperchaotic system

2012

In order to understand the onset of hyperchaotic behavior recently observed in many systems, we study bifurcations in the modified Chen system leading from simple dynamics into chaotic regimes. In particular, we demonstrate that the existence of only one fixed point of the system in all regions of parameter space implies that this simple point attractor may only be destabilized via a Hopf or double Hopf bifurcation as system parameters are varied. Saddle-node, transcritical and pitchfork bifurcations are precluded. The normal form immediately following double Hopf bifurcations is constructed analytically by the method of multiple scales. Analysis of this generalized double Hopf normal form …

Hopf bifurcation at infinity for planar vector fields

2007

We study, from a new point of view, families of planar vector fields without singularities $ \{ X_{\mu}$  &nbsp:&nbsp  $-\varepsilon < \mu < \varepsilon\} $ defined on the complement of an open ball centered at the origin such that, at $\mu=0$, infinity changes from repellor to attractor, or vice versa. We also study a sort of local stability of some $C^1$ planar vector fields around infinity.

Two-photon laser dynamics.

1995

Degenerate as well as nondegenerate three-level two-photon laser (TPL) models are derived. In the limit of equal cavity losses for both fields, it is shown that the nondegenerate model reduces to the degenerate one. We also demonstrate the isomorphism existing between our degenerate TPL model and that of a dressed-state TPL. All these models contain ac-Stark and population-induced shifts at difference from effective Hamiltonian models. The influence of the parameters that control these shifts on the nonlinear dynamics of a TPL is investigated. In particular, the stability of the periodic orbits that arise at the Hopf bifurcation of the system and the extension of the self-pulsing domains of…

Performance of a propeller embedded in the flowfield of a wing

1996

Are we "experienced listeners"? A review of the musical capacities that do not depend on formal musical training.

2006

The present paper reviews a set of studies designed to investigate different aspects of the capacity for processing Western music. This includes perceiving the relationships between a theme and its variations, perceiving musical tensions and relaxations, generating musical expectancies, integrating local structures in large-scale structures, learning new compositional systems and responding to music in an emotional (affective) way. The main focus of these studies was to evaluate the influence of intensive musical training on these capacities. The overall set of data highlights that some musical capacities are acquired through exposure to music without the help of explicit training. These ca…

Tonos condicionados por la estructura métrica y pies mínimamente recursivos en Chugach Alutiiq

2016

This article presents a reanalysis of the foot-based phonology of Chugach Alutiiq (henceforth CA), a language that displays a complex mixed ternary–binary rhythm, as well as metrically conditioned distributions of pitch, fortition and vowel lengthening. Elaborating on earlier analyses of CA that had posited some kind of ternary constituent (Hewitt, 1991, 1992; Leer, 1985a, 1985b, 1985c; Rice, 1992), we propose CA should be analyzed by means of the Internally Layered Ternary (ILT) foot, a minimal recursive foot (Prince, 1980; Selkirk, 1980), which was recently revived in a typological study of binary–ternary stress (Martínez-Paricio & Kager, 2015). It will be argued that ILT feet capture CA’…