The control strategies of blade loads are proposed for the characteristics of blade stresses of variable-speed variablepitch wind turbine. Blade loads are divided into two static and dynamic components. The pitch angle and generator torque are controlled by Single neuron PID controller in the static part. Variables are converted from rotational coordinate to fixed coordinate through multi-blade...

The structural properties of Higher harmonic Aeroacoustic Rotor Test (HART I) blades have been measured using the original set of blades tested in the wind tunnel in 1994. A comprehensive rotor dynamics analysis is performed to address the effect of the measured blade properties on airloads, blade motions, and structural loads of the rotor. The measurements include bending and torsion stiffness...

Salt-affected soil is one of the most important abiotic stresses, leading to reduce rice productivity in many regions of the world. The objective of this investigation was to determine the Na, soluble sugar and starch contents and expression of some starch-related genes in two genotypes, Pokkali (salt tolerant) and IR29 (salt sensitive), grown under 200 mM NaCl. Three-week-old rice seedlings cv...

∗ This work is supported by the U. S. Department of Energy under Contract DE-AC04-94AL85000. Ψ This paper is declared a work of the U. S. Government and is not subject to copyright protection in the United States. ABSTRACT A fatigue test of a wind turbine blade was conducted at the National Renewable Energy Laboratory. Acoustic emission monitoring of the test was performed, starting with the se...

In this paper, the sensitivity of the structural integrity of wind turbine blades to debonding of the shear web from the spar cap was investigated. In this regard, modal analysis, static and fatigue testing were performed on a 45.7 m blade for three states of the blade: (i) as received blade (ii) when a crack of 200 mm was introduced between the web and the spar cap and (iii) when the crack was...

The extremely thick blade root airfoils of the modern megawatt-scale wind turbines are prone to having sharp stall characteristics with associated unsteady aerodynamic blade loading and fatigue. With current technology designs reaching 45% thickness, these thick airfoils are incapable of producing high lift, and as a consequence they are aerodynamically and structurally sub-optimal. A computati...

In above rated conditions, wind turbines are often subjected to undesirable high structural loading. We investigate two feedback control techniques in combination with a feedforward control method for reducing blade flap bending loads in above rated wind conditions. The feedback controls studied include both disturbance accommodating/tracking and integral augmented/repetitive types that incorpo...

In the first paper of this report “Toward phonetically grounded distinctive features. Part I: Acoustic-articulatory correlations in a four-region model of the vocal tract”, the formant frequencies F1–F4 and the quality (or gain) factors Q1–Q4 are correlated with the positions, areas, or area ratios formed by the four active articulators: tongue root, tongue body, blade, lips. Among the findings...

An aeroelastic model of a smart rotor system (which incorporates blade-mounted trailing-edge flap actuators and conventional root pitch actuation) is presented in linear time invariant state space form. The servo-flap deflections are modeled as producing incremental lift and moment variations, so that any linear aerodynamic actuator can be evaluated. This smart rotor model is used to conduct pa...