Atmospheric turbulence parameters for modeling wind turbine dynamics

A model which can be used to predict the response of wind turbines to atmospheric turbulence is given. The model was developed using linearized aerodynamics for a three-bladed rotor and accounts for three turbulent velocity components as well as velocity gradients across the rotor disk. Typical response power spectral densities are shown. The system response depends critically on three wind and turbulence parameters, and models are presented to predict desired response statistics. An equation error method, which can be used to estimate the required parameters from field data, is also presented

Wind response characteristics of horizontal axis wind turbines

It was the objective of the work reported here, and in the companion paper 1 . A broader examination of wind turbine dynamic response to turbulence, and attempts to ascertain the features of turbulence that wind turbines are most sensitive to were made. A statistical description of the wind input including all three wind components and allowing linear wind gradients across the rotor disk, was used together with quasi-static aerodynamic theory and an elementary structural model involving only a few degrees of freedom. The idea was to keep the turbine model simple and show the benefits of this type of statistical wind representation before attempting to use a more complex turbine model. As far as possible, the analysis was kept in the simplest form, while still preserving key physical responses

Microcomputerized electric field meter diagnostic and calibration system

A computerized field meter calibration system which includes an apparatus for testing the calibration of field meters normally utilized for measuring electromagnetic field potentials is described. A reference voltage is applied to the field meter for causing signals to be produced on the output terminals thereof. A bank of relays is provided for selectively connecting output terminals of the field meter to a multiplexer by means of a digital voltmeter and an oscilloscope. A frequency-shift-keyed receiver is also connected to one of the terminals of the field meter for transmitting and converting a frequency shift keyed signal to a digital signal which is, subsequently, applied to the multiplexer

Wind turbulence inputs for horizontal axis wind turbines

Wind turbine response characteristics in the presence of atmospheric turbulence was predicted using two major modeling steps. First, the important atmospheric sources for the force excitations felt by the wind turbine system were identified and characterized. Second, a dynamic model was developed which describes how these excitations are transmitted through the structure and power train. The first modeling step, that of quantifying the important excitations due to the atmospheric turbulence was established. The dynamic modeling of the second step was undertaken separately

Multi-input, multi-output regulator design for constant disturbances and non-zero set points with application to automatic landing in a crosswind

Undesirable steady offsets result when a stationary, linear regulator using state feedback is subjected to constant disturbances and/or non-zero setspoints. To eliminate these offsets, the disturbances and non-zero setpoints can be fed forward to the control. Only when the number of outputs is less than or equal to the number of control inputs can the outputs be maintained at arbitrary non-zero setpoints. The state and the disturbance may be estimated using a constant gain Kalman filter or by modeling the constant disturbances as exponentially correlated processes with long correlation times

Synthesis and Characterization of Branched Polyelectrolytes: Star-branched NaPSS

In this thesis, we examined the effect of branching on the solution characteristics of polyelectrolytes using a set of star-branched NaPSS. The polystyrene precursors to these polyelectrolytes were synthesized using anionic polymerization allowing for the production of three distinct groups of star-branched polystyrenes with varying functionality and arm length. Following sulfonation, several methods commonly employed in the literature for evaluation of sulfonation degree we established that sulfonation was quantitative. TGA was also demonstrated to reveal important characteristics of the sample. We used aqueous SEC coupled with a multiple angle light scattering detector to determine several molecular characteristics of the star-branched NaPSS samples. Linear NaPSS synthesized via radical polymerization and sulfonation of polystyrene were characterized and important differences between NaPSS synthesized by the two methods were established. Dynamic light scattering experiments established a qualitative link between the presence of a slow diffusive mode and the degree of sulfonation. The branching parameter g was determined for the star-branched NaPSS samples and compared to theoretical predictions. Static light scattering experiments were performed to elucidate the effect of Cs on the Rg, where it was determined that Rg ~ Cs-0.11 for the whole range of samples. The apparent persistence length was determined and relations were established for its variation as a function of Cs, f and degree of arm polymerization. Additionally, no agreement was found between theoretical predictions of g and experimentally determined ones. A method was developed that enabled the determination of molecular dimensions of star-branched NaPSS using AFM with a high degree of agreement with the radii established using scattering methods on solutions of the polymers. The intrinsic viscosity could reliably be determined in solutions with Cs using either a Huggins or Wolf equation. For solutions with no Cs, the Huggins equation fit over the data at low Cp was confirmed by AFM measurements of the dimensions of the polyelectrolyte and comparisons to the radius determined from the intrinsic viscosities calculated using the two equations to be more accurate. The values of g‟ were calculated for solutions of the NaPSS stars in water and compared with theory

Federalism Gone Far Astray from Policy and Constitutional Concerns: The Admissions of Convictions to Impeach by State\u27s Rules-1990-2004

This is a micro study of federalism in action. This study identifies, ranks, and evaluates the current federal and state rules regulating the same issue-whether to admit prior convictions to impeach a witness and the appropriate standards for doing so. Over the last several decades, there has been an almost unanimous chorus of criticism regarding the wholesale admission of convictions, ostensibly only to impeach, especially when prosecutors are authorized by an evidence rule to use convictions to impeach the testimony of an accused in a criminal case. Despite this criticism, this study, and a companion study of how state supreme courts interpret these rules, provide a basis for concluding that this admission avenue persists and results in the admission of, in all probability, thousands of convictions against hundreds of witnesses in the United States each year

Differentiation of mammalian vestibular hair cells from conditionally immortal, postnatal supporting cells

We provide evidence from a newly established, conditionally immortal cell line (UB/UE-1) that vestibular supporting cells from the mammalian inner ear can differentiate postnatally into more than one variant of hair cell. A clonal supporting cell line was established from pure utricular sensory epithelia of H2kbtsA58 transgenic mice 2 d after birth. Cell proliferation was dependent on conditional expression of the immortalizing gene, the “T” antigen from the SV40 virus. Proliferating cells expressed cytokeratins, and patch-clamp recordings revealed that they all expressed small membrane currents with little time-dependence. They stopped dividing within 2 d of being transferred to differentiating conditions, and within a week they formed three defined populations expressing membrane currents characteristic of supporting cells and two kinds of neonatal hair cell. The cells expressed several characteristic features of normal hair cells, including the transcription factor Brn3.1, a functional acetylcholine receptor composed of a9 subunits, and the cytoskeletal proteins myosin VI, myosin VIIa, and fimbrin. Immunofluorescence labeling and electron microscopy showed that the cells formed complex cytoskeletal arrays on their upper surfaces with structural features resembling those at the apices of normal hair cells. The cell line UB/UE-1 provides a valuable in vitro preparation in which the expression of numerous structural and physiological components can be initiated or upregulated during early stages of mammalian hair cell commitment and differentiation

As-built design specification of the CAMS/CAS interface tape report generation program

There are no author-identified significant results in this report