Simulazione del volo di un catamarano con hydrofoil

Velocity prediction program per catamarano con V-foil anteriori e T-foil posteriori, simulazione di volo 3DOF con analisi della stabilità e dei carichi applicati.

Improved hybrid computer vehicle handling program. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Stability enhancement of DFIG wind turbine using LQR pitch control over rated wind speed

A novel pitch control design method is proposed for the doubly fed induction generator (DFIG) wind turbine (WT) using linear quadratic regulator (LQR). A seven-order model represents the DFIG WT which is linearized by truncated Taylor series expansion. A systematic approach is adopted to determine the weighting matrices in LQR design for the optimal solution. Simulations have been carried out to compare the performance of the proposed LQR pitch control method against a PI pitch control for small and large disturbances. It is shown that the proposed control method enhances low-voltage ride-through capability and improves system damping under large disturbances.

Hingeless-rotor aeromechanical stability in axial and forward flight with wake dynamics

A finite-state wake model is used to investigate aeromechanical stability of hingeless-rotor helicopters in the ground-contact, hover and trimmed-night conditions. The investigation covers three items: (1) the convergence of the damping with increasing number of wake harmonics for the lag regressing, and body pitch and roll modes; (2) a parametric study of the damping over a range of thrust level, advance ratio and number of blades; and (3) correlations, primarily with the damping and frequency measurements of these lag and body modes. The convergence and parametric studies are conducted in the hover and trimmed-flight conditions; they include predictions from the widely used dynamic inflow model. The correlations are conducted in the ground-contact conditions and include predictions from the dynamic inflow and vortex models; recently, this vortex model is proposed for the axial-flight conditions and is used to investigate the coupled free vibrations of rotor flapping and body modes. The convergence and parametric studies show that a finite-state wake model that goes well beyond the dynamic inflow model is required for fairly converged damping, Moreover, the correlations from the finite-state wake, dynamic inflow and vortex models are generally satisfactory.

Stability of a cylindrical plasma in the presence of a monotonic field-II

The stability of an incompressible inviscid, perfectly conducting cylindrical plasma against azimuthal disturbances in the presence of a monotonic decreasing magnetic field having a constant pitch is discussed by using energy principle. The results obtained by this principle are compared for m = 1 mode (which is a dangerous mode in which there is a lateral shift of the entire column) with that obtained by normal mode analysis. It is found that m = 1 mode is always unstable. Further, an axial line current, external axial field and the surface tension tend to stabilise m ≠ modes.

Response, loads, and stability of interconnected rotor-body systems

A rotor-body system with blades interconnected through viscoelastic elements is analyzed for response, loads, and stability in propulsive trim in ground contact and under forward-flight conditions, A conceptual model of a multibladed rotor with rigid flap and lag motions, and the fuselage with rigid pitch and roll motions is considered, Although the interconnecting elements are placed in the in-plane direction, considerable coupling between the flap-lag motions of the blades can occur in certain ranges of interblade element stiffness, Interblade coupling can yield significant changes in the response, loads, and stability that are dependent on the interblade element and rotor-body parameters, Ground resonance stability investigations show that by tuning the interblade element stiffness, the ground resonance instability problem can be reduced or eliminated, The interblade elements with damping and stiffness provide an effective method to overcome the problems of ground and air resonance.

Transient analysis of variable-speed wind turbines at wind speed disturbances and a pitch control malfunction

As wind power generation undergoes rapid growth, new technical challenges emerge: dynamic stability and power quality. The influence of wind speed disturbances and a pitch control malfunction on the quality of the energy injected into the electric grid is studied for variable-speed wind turbines with different power-electronic converter topologies. Additionally, a new control strategy is proposed for the variable-speed operation of wind turbines with permanent magnet synchronous generators. The performance of disturbance attenuation and system robustness is ascertained. Simulation results are presented and conclusions are duly drawn. (C) 2010 Elsevier Ltd. All rights reserved.

Issues in the development of pitch labelling skill

Pitch discrimination skills are important for general musicianship. The ability to name musical notes or produce orally any named note without the benefit of a known reference is called Absolute Pitch (AP) and is comparatively rare. Relative Pitch (RP) is the ability to name notes when a known reference is available. AP has historically been regarded as being innate. This paper will examine the notion that pitch discrimination skill is based on knowledge constructed through a suite of experiences. That is, it is learnt. In particular, it will be argued that early experiences promote the development of AP. Second it will argue that AP and RP represent different types of knowledge, and that this knowledge emerges from different experiences. AP is a unique research phenomenon because it spans the fields of cognition and perception, in that it links verbal labels with physiological sensations, and because of its rarity. It may provide a vantage for investigating the nature/nurture of musicianship; expertise; knowledge structure development; and the role of knowledge in perception. The study of AP may inform educational practice and curriculum design both in music and cross-curriculur. This paper will report an initial investigation into the similarities and differences between the musical experiences of AP possessors and the manifestation of their AP skill. Interview and questionnaire data will be used for the development and proposal of a preliminary model for AP development.

Diversity of accuracy profiles for absolute pitch recognition

Most advanced musicians are able to identify and label a heard pitch if given an opportunity to compare it to a known reference note. This is called ‘relative pitch’ (RP). A much rarer skill is the ability to identify and label a heard pitch without the need for a reference. This is colloquially referred to as ‘perfect pitch’, but appears in the academic literature as ‘absolute pitch’ (AP). AP is considered by many as a remarkable skill. As people do not seem able to develop it intentionally, it is generally regarded as innate. It is often seen as a unitary skill and that a set of identifiable criteria can distinguish those who possess the skill from those who do not. However, few studies have interrogated these notions. The present study developed and applied an interactive computer program to map pitch-labelling responses to various tonal stimuli without a known reference tone available to participants. This approach enabled the identification of the elements of sound that impacted on AP. Pitch-labelling responses of 14 participants with AP were recorded for their accuracy. Each participant’s response to the stimuli was unique. Their accuracy of labelling varied across dimensions such as timbre, range and tonality. The diversity of performance between individuals appeared to reflect their personal musical experience histories.