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Results for “tracked winds”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Description of Seasat radiometer status and results

Improved geophysical algorithms are shown to be able to determine sea surface temperature (SST) to an accuracy of 1 C (1 sigma) under favorable surface and atmospheric conditions over an SST range of 10-30 C. Under similar conditions, the radiometer wind retrievals track the scatterometer winds within a scatter of 2 m/s (1 sigma) over a wind speed range of 0-25 m/s. These conditions require that contamination from land, rain, sun glint, and radio frequency interference be avoided. What is more, water vapor determinations in the midlatitudes and in the tropical Pacific are found to agree with estimates of precipitable water from radiosondes to within 10%.

Lipes, R. G.↗
NASA NTRS1984

Total energy-rate feedback for automatic glide-slope tracking during wind-shear penetration

Low-altitude wind shear is recognized as an infrequent but significant hazard to all aircraft during the take-off and landing phases of flight. A total energy-rate sensor was developed for measuring the specific total energy rate of an airplane with respect to the air mass. Control-system designs, both with and without energy-rate feedback, for the approach to landing of a transport airplane through a severe-wind-shear and gust environment are presented in order to evaluate this application of the sensor. A system model incorporates wind-shear-dynamics equations with the airplane equations of motion to permit analysis of the control systems under various wind-shear conditions. The control systems are designed using optimal-output feedback and are analyzed using frequency-domain control-theory techniques. Control-system performance is evaluated using a complete nonlinear simulation of the airplane combined with a severe-wind-shear and gust data package. This evaluation is concerned with control system stability and regulation capability only.

Belcastro, C. M.↗
NASA NTRS1980

On the constancy of solar particle fluxes from track, thermoluminescence and solar wind measurements in lunar rocks

Evidence contained within lunar rocks concerning possible variations in solar activity over the last 1 to 2 million years is reviewed. The effects of solar wind particles, which are implanted at shallow depths, solar flare protons, which produce thermoluminescence as well as stable and radionuclides, and solar flare heavy nuclei, which produce tracks, are considered, and the quality and limitations of nuclear tracks measurements as indicators of solar flare flux histories are discussed. Methods used for the determination of the solar flare track production rate, which must be known in order to measure lunar rock surface exposure times, are compared, and it is concluded that most of the evidence favors the rate obtained by Blanford et al. (1975). Information on the constancy of the solar flare particle flux obtained by comparison of the effects of different surface phenomena with solar particle effects is then illustrated for the cases of comparisons between solar flare tracks and microcrater densities, solar flare particle fluxes measured over different periods, and comparisons of the solar flare track production rate with the solar wind flux and microcratering rate. It is noted that these studies provide no evidence for a change in solar particle flux by more than a factor of two over the last 10,000 to 1 million years, or for a change in the solar flare Fe/H ratio in the last 2 million years.

Zinner, E.↗
NASA NTRS1989

Neptune's wind speeds obtained by tracking clouds in Voyager images

Images of Neptune obtained by the narrow-angle camera of the Voyager 2 spacecraft reveal large-scale cloud features that persist for several months or longer. The features' periods of rotation about the planetary axis range from 15.8 to 18.4 hours. The atmosphere equatorward of -53 deg rotates with periods longer than the 16.05-hour period deduced from Voyager's planetary radio astronomy experiment (presumably the planet's internal rotation period). The wind speeds computed with respect to this radio period range from 20 meters per second eastward to 325 meters per second westward. Thus, the cloud-top wind speeds are roughly the same for all the planets ranging from Venus to Neptune, even though the solar energy inputs to the atmospheres vary by a factor of 1000.

Hammel, H. B.↗
NASA NTRS2003

HARLIE Aerosol and Cloud Structure and Wind Observations during HARGLO and IHOP

The Holographic Airborne Rotating Lidar Instrument Experiment (HARLIE) is a conical-scanning, 1-micron wavelength lidar that has been adapted for ground-based applications and used to infer horizontal wind information by tracking the motions of aerosol and cloud scattering structures. In addition, HARLIE's rapid continuous scanning enables boundary layer statistics and a new cloud lidar data product that gives cloud coverage as a function of altitude with high temporal resolution. HARLIE has been used in several field campaigns while developing the techniques for wind, boundary layer (BL), and cloud data products. These campaigns involved a variety of wind measuring instruments including rawindsondes, cloud-tracked winds from video imagery, Doppler lidars and Doppler radars. HARGLO-2 was one of these campaigns and was dedicated to wind profile intercomparisons over a 1-week period in November of 2001. The most recent of these campaigns was the International H20 Project (IHOP) located in the Southern Great Plains of the US during May and June of 2002.

Schwemmer, Geary K.↗
DOE OSTI2026

Stereo-vision thermal imaging system for tracking flying animals in wind farm areas (CRADA #763) Abstract

CRADA 763: abstract ThermalTracker-3D (TT3D) is a stereo vision thermal imaging system that provides 3D flight information on detected birds, bats, and other flying targets. The system was initially developed for use in the siting and monitoring of offshore wind projects to establish pre-construction and operation collision risk data but can be applied to terrestrial wind energy projects as well as national security monitoring. This technology will reduce monitoring cost, decrease processing time, and provide more accurate data for wind energy developers/operators and regulatory agencies. While the current technology is at a high level of readiness, Technology Readiness Level (TRL) 7, there remain several barriers to commercialization, particularly around ease-of-use, that result in a low Adoption Readiness Level (ARL). The proposed work will advance commercialization readiness by streamlining calibration methods for built systems. This work will:1. 1. develop a software package for factory and dynamic calibration processes 2. test that package with existing prototype TT3D systems, and 3. conduct outreach with industry end-users.

ThermalTracker↗
DOE OSTI2020

Design and analysis of a wake steering controller with wind direction variability

Wind farm control strategies are being developed to mitigate wake losses in wind farms, increasing energy production. Wake steering is a type of wind farm control in which a wind turbine's yaw position is misaligned from the wind direction, causing its wake to deflect away from downstream turbines. Current modeling tools used to optimize and estimate energy gains from wake steering are designed to represent wakes for fixed wind directions. However, wake steering controllers must operate in dynamic wind conditions and a turbine's yaw position cannot perfectly track changing wind directions. Research has been conducted on robust wake steering control optimized for variable wind directions. In this paper, the design and analysis of a wake steering controller with wind direction variability is presented for a two-turbine array using the FLOw Redirection and Induction in Steady State (FLORIS) control-oriented wake model. First, the authors propose a method for modeling the turbulent and low-frequency components of the wind direction, where the slowly varying wind direction serves as the relevant input to the wake model. Next, we explain a procedure for finding optimal yaw offsets for dynamic wind conditions considering both wind direction and yaw position uncertainty. We then performed simulations with the optimal yaw offsets applied using a realistic yaw offset controller in conjunction with a baseline yaw controller, showing good agreement with the predicted energy gain using the probabilistic model. Using the Gaussian wake model in FLORIS as an example, we compared the performance of yaw offset controllers optimized for static and dynamic wind conditions for different turbine spacings and turbulence intensity values, assuming uniformly distributed wind directions. For a spacing of five rotor diameters and a turbulence intensity of 10 %, robust yaw offsets optimized for variable wind directions yielded an energy gain equivalent to 3.24 % of wake losses recovered, compared to 1.42 % of wake losses recovered with yaw offsets optimized for static wind directions. In general, accounting for wind direction variability in the yaw offset optimization process was found to improve energy production more as the separation distance increased, whereas the relative improvement remained roughly the same for the range of turbulence intensity values considered.

17 WIND ENERGY↗
DOE OSTI2021

Wake Steering Wind Farm Control With Preview Wind Direction Information: Preprint

Wake steering is a wind farm control strategy in which upstream turbines operate with a yaw misalignment to deflect their wakes away from downstream turbines, yielding a net power gain for the wind plant. But the inability of wake steering controllers to perfectly track the wind direction leads to suboptimal performance. In this paper, we propose the use of preview wind direction measurements upstream of the turbine to improve controller performance by anticipating wind direction changes. Further, data from an operational wind plant are used to determine realistic preview measurement accuracy. Using the FLORIS engineering wind farm control tool, we compare the performance of standard and preview-enabled baseline and wake steering control for a two-turbine array during below-rated operation. Assuming perfect preview information, preview-based wake steering increases energy production by the equivalent of 9.5% of the baseline wake losses, compared to a wake loss recovery of 5.6% with standard wake steering. However, when realistic measurement accuracy is included, the preview-based controller provides no advantage over standard control, motivating the need for more sophisticated control and wind direction forecasting strategies.

49 EE - Wind and Water Power Program - Wind (EE-4W↗
NASA NTRS1987

Fuel penalties and time flexibility of 4D flight profiles under mismodeled wind conditions

A parametric sensitivity study was conducted to evaluate time flexibility and fuel penalties associated with 4D operations in the presence of mismodeled wind. The final cruise and descent segments of a flight in an advanced time-metered air traffic control environment were considered. Optimal performance of a B-737-100 airplane in known, constant winds was determined. Performance in mismodeled wind was obtained by tracking no-wind reference profiles in the presence of actual winds. The results of the analysis are presented in terms of loss of time flexibility and fuel penalties compared to the optimum performance in modeled winds.

Williams, David H.↗
NASA NTRS1986

Mean zonal winds on Venus from Doppler tracking of the Vega balloons

Doppler measurements of the two Vega balloons yield the following provisional estimates for the mean zonal wind velocity at the 53-54 km level in the Venus atmosphere: 69 + or - 1 m/sec for Vega 1 and 66 + or - 1 m/sec for Vega 2, with westward flow. The wind data show a perturbation which might be an evidence of solar tides.

Andreev, R. A.↗
NASA NTRS2000

[Measurement of Speed and Direction of Ocean Surface Winds Using Quik Scat Scatterometer]

The SeaWinds on QuikSCAT scatterometer was developed by NASA JPL to measure the speed and direction of ocean surface winds. Simulations performed to estimate the performance of the instrument prior to its launch have indicated that the mid-swath accuracy is worse than that of the rest of the swath. This behavior is a general characteristic of scanning pencil beam scatterometers. For SeaWinds, the accuracy of the rest of the swath, and the size of the swath are such that the instrument meets its science requirements despite mid-swath shortcomings. However, by understanding the problem at mid-swath, we can improve the performance there as well. We discuss the underlying causes of the problem in detail and propose a new wind retrieval algorithm which improves mid-swath performance. The directional discrimination ability of the instrument varies with cross track distance wind speed, and direction. By estimating the range of likely wind directions for each measurement cell, one can optimally apply information from neighboring cells where necessary in order to reduce random wind direction errors without significantly degrading the resolution of the resultant wind field. In this manner we are able to achieve mid-swath RMS wind direction errors as low as 15 degrees for low winds and 10 degrees for moderate to high winds, while at the same time preserving high resolution structures such as cyclones and fronts.

Stiles, Bryan↗
NASA NTRS1975

Development and testing of a portable wind sensitive directional air sampler

A portable wind sensitive directional air sampler was developed as part of an air pollution source identification system. The system is designed to identify sources of air pollution based on the directional collection of field air samples and their analysis for TSP and trace element characteristics. Sources can be identified by analyzing the data on the basis of pattern recognition concepts. The unit, designated Air Scout, receives wind direction signals from an associated wind vane. Air samples are collected on filter slides using a standard high volume air sampler drawing air through a porting arrangement which tracks the wind direction and permits collection of discrete samples. A preset timer controls the length of time each filter is in the sampling position. At the conclusion of the sampling period a new filter is automatically moved into sampling position displacing the previous filter to a storage compartment. Thus the Air Scout may be set up at a field location, loaded with up to 12 filter slides, and left to acquire air samples automatically, according to the wind, at any timer interval desired from 1 to 30 hours.

Deyo, J.↗
NASA NTRS1972

Meteorological rocket data processor and results from the solar eclipse of 7 March 1970.

A comprehensive digital computer program is described which automatically processes precision digitized data from conventional rocketsondes and radars to produce accurately corrected temperatures and winds together with estimated uncertainties at each point. Underlying models for the systematic errors in the Arcasonde 1A temperature sensor and the radar-tracked parachute wind sensor, and for the uncertainty in corrected results are presented. Techniques used to automatically edit, synchronize and filter data are also given. Performance is illustrated by graphical output from the eight meteorological soundings in the rocket series conducted at Wallops Island, Va., during the Mar. 7, 1970 solar eclipse. An operational version (METROK) of the program is in use at NASA Wallops Station.

Staffanson, F. L.↗
NASA NTRS1986

Implications of preliminary Vega balloon results for the Venus atmosphere dynamics

The typical 1-2 m/sec vertical winds encountered by the Vega balloons probably result from thermal convection. The consistent 6.5-kelvin differential between the Vega 1 and Vega 2 temperatures is attributable to disturbances of synoptic or planetary scale. According to the Doppler tracking the winds were stronger than on earlier missions, perhaps because of solar thermal tides. The motions of Vega 2 may have been affected by waves from mountainous terrain.

Blamont, J. E.↗
NASA NTRS1992

Pointing-error simulations of the DSS-13 antenna due to wind disturbances

Accurate spacecraft tracking by the NASA Deep Space Network (DSN) antennas must be assured during changing weather conditions. Wind disturbances are the main source of tracking errors. The development of a wind-force model and simulations of wind-induced pointing errors of DSN antennas are presented. The antenna model includes the antenna structure, the elevation and azimuth servos, and the tracking controller. Simulation results show that pointing errors due to wind gusts are of the same order as errors due to static wind pressure and that these errors (similar to those of static wind pressure) satisfy the velocity quadratic law. The presented methodology is used for wind-disturbance estimation and for the design of an antenna controller with wind-disturbance rejection properties.

Gawronski, W.↗