Search NASA⌕ Search

SEARCH · Search NASA

Results for “Trac”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Data for Clumping Index Estimation With 30°-tilted Cameras in Row Crops: Evaluation of Methods and Segment Size Effects

The clumping index (CI) quantifies the spatial distribution of foliage elements and is essential for accurately estimating the plant area index (PAI), canopy radiative transfer, and photosynthesis. Traditionally, the finite-length averaging method (LX), the gap size distribution method (CC), and a combined approach of CC and LX (CLX) have been applied to instruments like TRAC and digital hemispherical photography to estimate CI. However, a comprehensive evaluation of these methods in row crops remains limited, especially regarding the influence of segment size on CI. Meanwhile, digital cameras offer a cost-effective and user-friendly solution for canopy measurements in row crops, yet their application in this context remains underexplored. In this study, we employed a new approach using a 30°-tilted digital camera to estimate CI in corn and soybean fields, applying the LX, CC, and CLX methods. We systematically assessed the performance of these three methods by combining field measurements in real-world fields with simulations using the LESS 3D radiative transfer model. Our results showed that CLX applied to the whole image and 45° segment offered accurate estimation of CI (bias within ±0.1, RMSE < 0.2) and PAI (bias within ±0.4, RMSE < 1) in real-world fields and LESS simulations. The accuracy of the LX method was highly sensitive to segment size, with the best performance observed at the 15° segment (PAI bias within ±0.4). In contrast, the CC method remained stable across different segment sizes, and its performance was generally comparable to that of LX, except at the 15° segment. Across view zenith angles, CI derived from CC generally showed a continuous increase, while those from LX and CLX followed a rising trend at small zenith angles but began to decline at 68°, likely due to an increasing proportion of no-gap segments. Seasonally, LX tended to show decreasing CI during early growth stages but increased as the canopy matured, whereas CC and CLX showed gradually increasing CI before plateauing at peak PAI. The 30°-tilted camera effectively captured CI variations across different angles and growth stages, making it a practical and robust instrument for row crop canopy structure analysis. Applying these CI methods to digital cameras offers a low-cost and accessible CI estimation alternative, improving canopy structure monitoring accuracy in row crops.

Modeling↗
NASA NTRS1995

Long range targeting for space based rendezvous

The work performed under this grant supported the Dexterous Flight Experiment one STS-62 The project required developing hardware and software for automating a TRAC sensor on orbit. The hardware developed by for the flight has been documented through standard NASA channels since it has to pass safety, environmental, and other issues. The software has not been documented previously, therefore, this report provides a software manual for the TRAC code developed for the grant.

Everett, Louis J.↗
NASA NTRS1997

How the Theory of Computing Can Help in Space Exploration

The opening of the NASA Pan American Center for Environmental and Earth Sciences (PACES) at the University of Texas at El Paso made it possible to organize the student Center for Theoretical Research and its Applications in Computer Science (TRACS). In this abstract, we briefly describe the main NASA-related research directions of the TRACS center, and give an overview of the preliminary results of student research.

Kreinovich, Vladik↗
NASA NTRS2001

Analysis of Measured and Predicted Acoustics From an XV-15 Flight Test

Flight acoustic and vehicle state data from an XV-15 acoustic flight test are examined. Flight predictions using TiltRotor Aeroacoustic Code (TRAC) are performed for a level flight (repeated) and four descent conditions (including a blade vortex interaction (BVI)). The assumptions and procedures used for TRAC flight predictions as well as the variability in flight measurements, which are used for input and comparison to predictions, are investigated in detail. Differences were found in the measured vehicle airspeed, altitude, glideslope, and vehicle orientation (yaw, pitch, and roll angle) between each of the repeat runs. These differences violate some of the prediction assumptions and significantly impacted the resulting acoustic predictions. Multiple acoustic pulses, with a variable time between the pulses, were found in the measured acoustic time histories for the repeat runs. These differences could be attributed in part to the variability in vehicle orientation. Acoustic predictions that used the measured vehicle orientation for the repeat runs captured this multiple pulse variability. Thickness noise was found to be dominant on approach for all the cases, except the BVI condition. After the aircraft passed overhead, broadband noise and low frequency loading noise were dominant. The predicted LowSPL time histories compared well with measurement on approach to the array for the non-BVI conditions and poorly for the BVI condition. Accurate prediction of the lift share between the rotor and fuselage must be known in order to improve predictions. At a minimum, measurements of the rotor thrust and tip-path-plane angle are critical to further develop accurate flight acoustic prediction capabilities.

Boyd, D. Douglas, Jr.↗
NASA NTRS2001

Analysis of Measured and Predicted Acoustics from an XV-15 Flight Test

Flight acoustic and vehicle state data from an XV-15 acoustic flight test are examined. Flight predictions using TRAC are performed for a level flight (repeated) and four descent conditions (including a BVI). The assumptions and procedures used for TRAC flight predictions as well as the variability in flight measurements, which are used for input and comparison to predictions, are investigated in detail. Differences were found in the measured vehicle airspeed, altitude, glideslope, and vehicle orientation (yaw, pitch and roll angle) between each of the repeat runs. These differences violate some of the prediction assumptions and significantly impacted the resulting acoustic predictions. Multiple acoustic pulses, with a variable time between the pulses, were found in the measured acoustic time histories for the repeat runs. These differences could be attributed in part to the variability in vehicle orientation. Acoustic predictions that used the measured vehicle orientation for the repeat runs captured this multiple pulse variability. Thickness noise was found to be dominant on approach for all the cases, except the BVI condition. After the aircraft passed overhead, broadband noise and low frequency loading noise were dominant. The predicted LowSPL time histories compared well with measurement on approach to the array for the non-BVI conditions and poorly for the BVI condition. Accurate prediction of the lift share between the rotor and fuselage must be known in order to improve predictions. At a minimum, measurements of the rotor thrust and tip-path-plane angle are critical to further develop accurate flight acoustic prediction capabilities.

Boyd, D. Douglas, Jr.↗
NASA NTRS2011

Modeling Off-Nominal Recovery in NextGen Terminal-Area Operations

Robust schedule-based arrival management requires efficient recovery from off-nominal situations. This paper presents research on modeling off-nominal situations and plans for recovering from them using TRAC, a route/airspace design, fast-time simulation, and analysis tool for studying NextGen trajectory-based operations. The paper provides an overview of a schedule-based arrival-management concept and supporting controller tools, then describes TRAC implementations of methods for constructing off-nominal scenarios, generating trajectory options to meet scheduling constraints, and automatically producing recovery plans.

Callantine, Todd J.↗
NASA NTRS2014

Towards a Formal Semantics of Flight Plans and Trajectories

In the National Airspace System, ight plans are often used only as a planning tool by air trac controllers and aircraft operators. These plans are implicitly translated into trajectories by the pilot or by the ight management system, and subsequently own by the aircraft. This translation process inevitably introduces di erences between the plan and the trajectory. However, given the current intended usage, exact correspondence between the plan and the trajectory is not needed. To achieve greater capacity and eciency, future air trac management concepts are being designed around the use of trajectories where predictability is extremely important. In this paper, a mathematical relationship between ight plans and trajectories is explored with the goal of making feasible, highly accurate predictions of future positions and velocities of aircraft. The goal here is to describe, in mathematically precise detail, a formal language of trajectories, whereby all receivers of the trajectory information will be able to arrive at precisely the same trajectory predication and to do this without having aircraft broadcast a large amount of data. Although even a four-dimensional ight plan is simple in structure, this paper will show that it is inherently ambiguous and will explore these issues in detail. In e ect, we propose that a rigorous semantics for ight plans can be developed and this will serve as an important stepping stone towards trajectory-based operations in the National Airspace System.

Hagen, George E.↗
DOE OSTI2025

Clumping index estimation with 30°-tilted cameras in row crops: Evaluation of methods and segment size effects

The clumping index (CI) quantifies the spatial distribution of foliage elements and is essential for accurately estimating the plant area index (PAI), canopy radiative transfer, and photosynthesis. Traditionally, the finite-length averaging method (LX), the gap size distribution method (CC), and a combined approach of CC and LX (CLX) have been applied to instruments like TRAC and digital hemispherical photography to estimate CI. However, a comprehensive evaluation of these methods in row crops remains limited, especially regarding the influence of segment size on CI. Meanwhile, digital cameras offer a cost-effective and user-friendly solution for canopy measurements in row crops, yet their application in this context remains underexplored. In this study, we employed a new approach using a 30°-tilted digital camera to estimate CI in corn and soybean fields, applying the LX, CC, and CLX methods. We systematically assessed the performance of these three methods by combining field measurements in real-world fields with simulations using the LESS 3D radiative transfer model. Our results showed that CLX applied to the whole image and 45° segment offered accurate estimation of CI (bias within ±0.1, RMSE < 0.2) and PAI (bias within ±0.4, RMSE < 1) in real-world fields and LESS simulations. The accuracy of the LX method was highly sensitive to segment size, with the best performance observed at the 15° segment (PAI bias within ±0.4). In contrast, the CC method remained stable across different segment sizes, and its performance was generally comparable to that of LX, except at the 15° segment. Across view zenith angles, CI derived from CC generally showed a continuous increase, while those from LX and CLX followed a rising trend at small zenith angles but began to decline at 68°, likely due to an increasing proportion of no-gap segments. Seasonally, LX tended to show decreasing CI during early growth stages but increased as the canopy matured, whereas CC and CLX showed gradually increasing CI before plateauing at peak PAI. The 30°-tilted camera effectively captured CI variations across different angles and growth stages, making it a practical and robust instrument for row crop canopy structure analysis. Furthermore, applying these CI methods to digital cameras offers a low-cost and accessible CI estimation alternative, improving canopy structure monitoring accuracy in row crops.

30°-tilted camera↗
DOE OSTI1995

Nuclear Safety [Vol. 36, No. 2, July-December 1995]

Nuclear Safety is a journal that covers significant issues in the field of nuclear safety. Its primary scope is safety in the design, construction, operation, and decommissioning of nuclear power reactors worldwide and the research and analysis activities that promote this goal, but it also encompasses the safety aspects of the entire nuclear fuel cycle, including fuel fabrication, spent-fuel processing and handling, and nuclear waste disposal, the handling of fissionable materials and radioisotopes, and the environmental effects of all these activities. Table of Contents for this issue follows. THE CHORNOBYL ACCIDENT: 195 The Chornobyl Accident Revisited, Part III: Chernobyl Source Term Release Dynamics and Reconstruction of Events During the Active Phase, A. R. Sich; GENERAL SAFETY CONSIDERATIONS: 218 Second ANS Workshop on the Safety of Soviet-Designed Nuclear Power Plants, R. A. Bari; 234 Elements of a Nuclear Criticality Safety Program, C. M. Hopper; 243 Rickover, Excellence, and Criticality Safety Programs, R. E. Wilson; ACCIDENT ANALYSIS: 249 Transient Analysis of the PIUS Advanced Reactor Design with the TRAC-PF1/MOD2 Code, B. E. Boyack, J. L Steiner, S. C. Harmony, H. J. Stumpf, and J. F. Lime; 278 The Hierarchy-By-Interval Approach to Identifying Important Models that Need Improvement in Severe-Accident Simulation Codes, T. J. Heames, M. Khatib-Rahbar, J. E. Kelly, R. P. Jenks-Johnson, and Y.-S. Chen; 290 RELAP5/MOD3 Code Coupling Model, R. P. Martin; 299 Missiles Caused by Severe Pressurized-Water Reactor Accidents, R. Krieg; DESIGN FEATURES: 310 Validation of COMMIX with Westinghouse AP-600 PCCS Test Data, J. G. Sun, T. H. Chien, J. Ding, and W T. Sha; ENVIRONMENTAL EFFECTS: 321 Spent Nuclear Fuel Characterization for a Bounding Reference Assembly for the Receiving Basin for Off-Site Fuel, S. D. Kahook, R. L. Garrett, L. R. Canas, and M J. Beckum; OPERATING EXPERIENCES: 332 Reactor Shutdown Experience, Compiled by J. W. Cletcher; U.S. NUCLEAR REGULATORY COMMISSION INFORMATION AND ANALYSES: 335 Reactor Coolant System Blowdown at Wolf Creek on September 17, 1994, J. V. Kauffman and S. L. Israel; RECENT DEVELOPMENTS: 344 Reports, Standards, and Safety Guides, D. S. Oueener; 349 Proposed Rule Changes as of June 30, 1995; ANNOUNCEMENTS: 320 Symposium on Acceptability of Risk From Radiation—Application to Manned Space Flight; 320 24th DOE/NRC Nuclear Air Cleaning and Treatment Conference; 361 Radiation Biology and Radiation Protection— Modern Developments and Tendencies in Radiation Biology; 362 1997 IEEE Sixth Conference on Human Factors and Power Plants; 354 The Authors; 360 Reviewers of Nuclear Safety, Vol. 36.

05 NUCLEAR FUELS↗
DOE OSTI2024

Industry Scan of Non-SF6 Gas-Insulated Technologies

Sulfur Hexafluoride (SF 6 ) is a specialty gas with excellent electrical insulation properties which has been used extensively in the power industry. This gas is unfortunately also one of the most potent greenhouse gases known to humanity. A 2014 report by the Intergovernmental Panel on Climate Change found that SF 6 has a global warming potential (GWP) 23,000 times higher than Carbon Dioxide, and has the highest GWP of all gases assessed (Myhre 2013). SF 6 is almost exclusively man-made and is produced for use as an insulator in high voltage electrical equipment. This makes the production and use of SF 6 one of the leading sources of anthropogenic climate change. Since SF 6 recognition as a significant contributor to climate change, most governments and organizations have sought ways to reduce or eliminate their use of this gas. Many utilities have initiated leak monitoring and repair programs which have significantly reduced emissions of this gas into the atmosphere. While leak reduction programs have been effective at reducing emission rates in the developed world, leak rates remain frozen at ~1% annually. However, one of the largest and fastest growing markets for this gas is in the developing world where emissions standards are often lacking (P&S Intelligence. 2023). To fully eliminate the environmental impacts of SF 6 , alternative technology is needed. The ideal replacement would be a technology that can fulfil the same role as SF 6 , at the same cost or cheaper, but without adverse environmental effects. Currently, no technology fits this description, however several promising technologies have begun to enter the market. This report was commissioned by the United States Department of Energy’s Office of Electricity under the Transformer Resilience and Advanced Components (TRAC) program to assess the state of industry adoption and manufacturing capability for SF 6 -free alternative technologies for use at the high-voltage level, and the primary barriers to broader adoption. While this report is tailored to the United States, the findings should be relevant to all stakeholders seeking to reduce SF 6 emissions.

24 - POWER TRANSMISSION AND DISTRIBUTION↗
NASA NTRS1991

Performance related issues in distributed database systems

The key elements of research performed during the year long effort of this project are: Investigate the effects of heterogeneity in distributed real time systems; Study the requirements to TRAC towards building a heterogeneous database system; Study the effects of performance modeling on distributed database performance; and Experiment with an ORACLE based heterogeneous system.

Mukkamala, Ravi↗
NASA NTRS1991

LLNL contributions to MPD thrusters for SEI

Some of the topics covered with respect to the Lawrence Livermore National Laboratory's (LLNL's) contributions to Magnetoplasmadynamic (MPD) Thrusters for the Space Exploration Initiative (SEI) include: an IR camera, plasma-induced erosion/redeposition, the Mirror Fusion Test Facility-B (MFTF-B), the Thruster Lifetime Test Facility, the RACE Compact Torus Accelerator Facility, and a RACE program summary. Some of the other topics addressed include: flux contours for HAM simulation, comparison of RACE data of plasma ring formation with the HAM 2-D magnetohydrodynamic code, and the 2-D Ring Acceleration Code (TRAC).

Hooper, Edwin Bickford↗
NASA NTRS1992

Automation of the targeting and reflective alignment concept

The automated alignment system, described herein, employs a reflective, passive (requiring no power) target and includes a PC-based imaging system and one camera mounted on a six degree of freedom robot manipulator. The system detects and corrects for manipulator misalignment in three translational and three rotational directions by employing the Targeting and Reflective Alignment Concept (TRAC), which simplifies alignment by decoupling translational and rotational alignment control. The concept uses information on the camera and the target's relative position based on video feedback from the camera. These relative positions are converted into alignment errors and minimized by motions of the robot. The system is robust to exogenous lighting by virtue of a subtraction algorithm which enables the camera to only see the target. These capabilities are realized with relatively minimal complexity and expense.

Redfield, Robin C.↗
NASA NTRS1991

Magnetic end effectors for space operations

The Magnetic End Effector (MEE) to be flown as part of the Dexterous End Effector (DEE) flight experiment was designed to operate with the Shuttle Remote Manipulator System (SRMS). Grappling or attachment of payloads is accomplished magnetically with two fault tolerant operations. The small magnetic grapple plate weighs far less than the standard grapple fixture; allows stacking and close spacing of payloads; and eliminates secondary release mechanisms. In addition to specifics regarding the MEE, the DEE project, Magnetic Attachment Tool (MAT), RMS-Force Torque Sensor (RMS-FTS), and Targeting and Reflective Alignment Concept (TRAC) are discussed.

Monford, Leo↗
NASA NTRS1995

Calculation of design load for the MOD-5A 7.3 mW wind turbine system

Design loads are presented for the General Electric MOD-SA wind turbine. The MOD-SA system consists of a 400 ft. diameter, upwind, two-bladed, teetered rotor connected to a 7.3 mW variable-speed generator. Fatigue loads are specified in the form of histograms for the 30 year life of the machine, while limit (or maximum) loads have been derived from transient dynamic analysis at critical operating conditions. Loads prediction was accomplished using state of the art aeroelastic analyses developed at General Electric. Features of the primary predictive tool - the Transient Rotor Analysis Code (TRAC) are described in the paper. Key to the load predictions are the following wind models: (1) yearly mean wind distribution; (2) mean wind variations during operation; (3) number of start/shutdown cycles; (4) spatially large gusts; and (5) spatially small gusts (local turbulence). The methods used to develop statistical distributions from load calculations represent an extension of procedures used in past wind programs and are believed to be a significant contribution to Wind Turbine Generator analysis. Test/theory correlations are presented to demonstrate code load predictive capability and to support the wind models used in the analysis. In addition MOD-5A loads are compared with those of existing machines. The MOD-5A design was performed by the General Electric Company, Advanced Energy Program Department, under Contract DEN3-153 with NASA Lewis Research Center and sponsored by the Department of Energy.

Mirandy, L.↗
NASA NTRS2000

NASA and Youth in the 21st Century

This document is several slides from a presentation: (1) shows the space shuttle main engine (SSME), and the characteristics; (2) shows models of the SSME High pressure Fuel Turbopump (HPFTP) Alternate Turbopump Design (ATD); (4) shows the X34, (5) a test firing of the Fast Trac Engine;(6) shows a thermal analysis for the housing and the Rotor. Several pictures do not have captions.

Roman, Jose↗
NASA NTRS2000

BOREAS RSS-7 LAI, Gap Fraction, and FPAR Data

The BOREAS RSS-7 team collected various data sets to develop and validate an algorithm to allow the retrieval of the spatial distribution of Leaf Area Index (LAI) from remotely sensed images. Ground measurements of LAI and Fraction of Photosynthetically Active Radiation (FPAR) absorbed by the plant canopy were made using the LAI-2000 and TRAC optical instruments during focused periods from 09-Aug-1993 to 19-Sep-1994. The measurements were intensive at the NSA and SSA tower sites, but were made just once or twice at auxiliary sites. The final processed LAI and FPAR data set is contained in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884).

Hall, Forrest G.↗
NASA NTRS1997

Simulation of Rotary-Wing Near-Wake Vortex Structures Using Navier-Stokes CFD Methods

This paper will use high-resolution Navier-Stokes computational fluid dynamics (CFD) simulations to model the near-wake vortex roll-up behind rotor blades. The locations and strengths of the trailing vortices will be determined from newly-developed visualization and analysis software tools applied to the CFD solutions. Computational results for rotor nearwake vortices will be used to study the near-wake vortex roll up for highly-twisted tiltrotor blades. These rotor blades typically have combinations of positive and negative spanwise loading and complex vortex wake interactions. Results of the computational studies will be compared to vortex-lattice wake models that are frequently used in rotorcraft comprehensive codes. Information from these comparisons will be used to improve the rotor wake models in the Tilt-Rotor Acoustic Code (TRAC) portion of NASA's Short Haul Civil Transport program (SHCT). Accurate modeling of the rotor wake is an important part of this program and crucial to the successful design of future civil tiltrotor aircraft. The rotor wake system plays an important role in blade-vortex interaction noise, a major problem for all rotorcraft including tiltrotors.

Kenwright, David↗