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All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Analysis and Evaluation of NASA's MK40B Six-Component Task Balance

The MK40B balance is NASA's newest balance of Task design. Its load range was optimized for use in the NASA Ames 11-ft Transonic Wind Tunnel. The balance was calibrated in 2019 in Calspan's Automatic Balance Calibration System. The data analysis was performed at the Ames Balance Calibration Laboratory. First, bi-directional characteristics of the six gage outputs of the balance were assessed by applying a semi-empirical test to the calibration data. These tests indicated that four of the six gages have bi-directional characteristics. Therefore, the use of absolute value terms in the regression models of the calibration data is justified. Then, the machine calibration data was analyzed using both the Non-Iterative and the Iterative Method. Analysis results for the two methods were compared using the percent contributions, the calibration load residuals, the primary sensitivities, and the principle linear terms. These results confirmed that the two methods describe bi-directional characteristics of the balance gages correctly. In addition, it was concluded that the load prediction accuracies of the two methods are the same for all practical purposes.

wind tunnel balance↗
NASA NTRS2001

Determining the Mass Density Along Magnetic Field Lines from Toroida Eigenfrequencies

Toroidal eigenfrequencies can be used to remotely sense the equatorial mass density rho(sub eq) and the density dependence along a magnetic field line. Here we present improvements to the method of Schulz [1996], which allows rho(sub eq) and the power law index alpha (for mass density along a field line proportional to R(sup -alpha), where R is the radial distance from the center of the Earth) to be determined from the y intercept and slope of a plot of toroidal frequency versus toroidal harmonic number n. Our modifications include a model form for eigenfrequencies with a fractional precision of 0.0005 for -6 less than or = alpha less than or = 6 and 2 less than or = L less than or = 8 (accuracy is doubtful beyond L = 5) and an iterative procedure for getting more accurate results than those found using Schulz's method. In addition, we do an analysis of the effect of random measurement errors. Observed frequencies need to be accurate to approx. 6% (3%) of the fundamental frequency in order to determine rho(sub eq) (alpha) to a precision of 30% (unity). We then apply our method to data generated using the Global Core Plasma Model for plasmaspheric mass density; our analysis demonstrates clearly bow the alpha index represents the mass density dependence on the outer part of the field line (R/(LR(sub E)) greater than or approx. 2/3).

Denton, R.↗
NASA NTRS1981

Sensitivity of wind analyses to barotropic energetics during summer

Three analysis schemes - the extended correction method of the University of Hawaii at Manoa (UHM), the National Meteorological Center (NMC) Hough analysis, and Sadler's subjective stream analysis (SUB) - were used to obtain grid-point winds using data for a five-day period in late summer, and barotropic energetics computations obtained using the three schemes for six limited regions in the Pacific and Indian Oceans were compared. Few differences were observed between UHM and NMC stream-function analyses, but significant differences were found in the wind fields and energetics obtained using the subjective method and the two objective methods in data-sparse regions. Major features in the local barotropic criteria field were found to be less sensitive to the analysis scheme used.

Sumi, A.↗
NASA NTRS1990

Boundary-layer stability analysis of flight-measured transition data

Correlation of in-flight boundary-layer transition experiments with linear boundary-layer stability theory contributes both to the validation of the numerical methods as well as the analysis of the measured transition process. Transition results obtained in a recent flight experiment, in which the extent of laminar flow and the transition process on the wing of a business-jet fitted with an instrumented glove section were determined, are analyzed. The experiment was conducted at freestream Mach numbers from 0.55 to 0.82, chord Reynolds numbers from 10 to 20 x 10 to the 6th, and leading-edge sweep angles 17 deg to 20 deg. The growth of both Tollmien-Schlichting and crossflow instabilities are predicted using the e exp n method for several flight conditions and the calculated n-factors at transition onset are correlated. Comparison of the measured dominant boundary-layer disturbance frequencies and the predicted unstable frequencies shows fair agreement for several of the flight conditions studied.

Obara, Clifford J.↗
DOE OSTI2025

Cluster-Graph Fingerprinting: A Framework for Quantitative Analysis of Machine-Learned Interatomic Model Training and Simulation Data

Machine-learned interatomic models represent a significant advancement in simulation methods, extending the predictive ability of first-principles methods to previously inaccessible length and time scales. However, the data-driven nature of these models can lead to difficult-to-detect errors that can compromise prediction accuracy. To address this challenge, we introduce a novel fingerprinting approach based on the Chebyshev Interaction Model for Efficient Simulation (ChIMES) ML-IAM graph-based descriptor. Our strategy enables efficient and statistically rigorous analysis of system configurations used in ML-IAM training and those generated by their application, e.g., in molecular dynamics simulations. We demonstrate that these fingerprints can effectively assess novelty of a configuration relative to an existing data set and determine dissimilarity among individual configurations, which are two key tasks in workflows for active learning-based ML-IAM training, data set curation, and on-the-fly uncertainty quantification.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Environmental Effects Assessment for Proposed Offshore Wind Farm off the Coast of Grays Harbor, Washington

Grays Harbor Wind LLC (GHW) is proposing to develop a floating offshore wind farm offshore of west Grays Harbor County, Washington (Grays Harbor). The proposed GHW Offshore Wind Project (Project) would entail construction, installation and operation of a 1,000-megawatt (MW) offshore wind farm consisting of approximately 75 floating units, each containing a floating foundation and wind turbine generator (WTG). The Project location is approximately 25 miles (21.7 nautical miles [nmi]) offshore west of Grays Harbor, at waters depths of 360 to 700 feet. The Pacific Northwest National Laboratory (PNNL) was contracted by Herrera Environmental Consultants, Inc. on behalf of GHW to carry out this preliminary scoping study to evaluate baseline conditions and potential effects on fish and marine mammals from development and operation of a floating offshore wind farm installed within a designated area off the coast of Washington1. Floating offshore wind units installed in an ocean environment as part of the Project would interact with marine wildlife. This Study report provides an initial data aggregation and analysis, using publicly available data, of the Project effects, both negative and positive, on the marine environment. The scope of this assessment is limited by the fact that the Project development is presently at the conceptual level. Data on marine organisms were aggregated and evaluated; however seabirds were evaluated by Herrera Environmental Consulting and, along with bats, were not included in the scope of this study. Significant additional work is necessary to characterize ocean, seafloor, and environmental conditions; select appropriate floating offshore wind technologies; identify construction methods and locations; and assess facility locations, including electrical interconnection. Data aggregation and analysis of seabirds and bats is also needed. Evaluation of the full range of potential environmental effects would be conducted following an award of a lease from the Bureau of Ocean Energy Management (BOEM) as part of the leasing, National Environmental Policy Act (NEPA)/State Environmental Policy Act (SEPA) environmental review and permitting processes. While this initial data aggregation and analysis uses best available public scientific information and current assumptions about the Project configuration, the effects discussed herein are based on the status of review to-date and may change as Project-specific details are developed.

17 WIND ENERGY↗
NASA NTRS1994

Some new mathematical methods for variational objective analysis

Numerous results were obtained relevant to remote sensing, variational objective analysis, and data assimilation. A list of publications relevant in whole or in part is attached. The principal investigator gave many invited lectures, disseminating the results to the meteorological community as well as the statistical community. A list of invited lectures at meetings is attached, as well as a list of departmental colloquia at various universities and institutes.

Wahba, Grace↗
NASA NTRS1986

Application of satellite data to the variational analysis of the three dimensional wind field

The use of a hybrid vertical velocity algorithm, composed of the kinematic and adiabatic methods of Pettersen (1956), to analyze three-dimensional wind fields is studied. The basic principles and advantages and disadvantages of the adiabatic and kinematic techniques are discussed. The adiabatic method is useful in the clear regions and above the tropopause and the kinematic method is applicable near the surface and in cloudy regions. The effects of a finite difference scheme and the objective analysis of Barnes (1973) on a wind field are investigated. The variational algorithm is evaluated by applying it to SESAME data collected in April 1979.

Chance, Barbara A.↗
NASA NTRS2024

SMAnalytics Automated Shape Memory Test Analysis Software User's Manual: UCFTC, UPER, and DSC Test Methods, Version 1.0.2

Over the course of 60 years of shape memory alloy research and development, the properties of these alloys have been measured using various testing methods, which are often customized by the organization performing the test. However, commercial adoption of shape memory alloys in aeronautic actuator applications requires reducing property uncertainty through standardizing test methods. Historically, differential scanning calorimetry (DSC) has been used to measure transformation temperatures under stress-free conditions. This testing method is well established, and tests are run under the applicable standard, ASTM F2004-17: Standard Test Method for Transformation Temperature of Nickel-Titanium Alloys by Thermal Analysis. Two other test methods for measuring strains and transformation temperatures under constant load or free recovery after prestraining have only recently been standardized—ASTM E3097: Standard Test Method for Mechanical Uniaxial Constant Force Thermal Cycling of SMAs (UCFTC) and ASTM E3098: Standard Test Method for Mechanical Uniaxial Pre-Strain and Thermal Free Recovery of SMAs (UPFR). These standards represent a critical step forward in producing reliable material property data for the use of these alloys in aeronautics and other commercial areas. However, no standard programs or software packages were previously available for postprocessing UCFTC- and UPFR-type test data to extract property data. Each organization that performed the testing analyzed data using its own custom manual methods, such as using a plot and a straight edge, spreadsheet plotting methods, or custom code routines, to extract the required values for strains, stresses, and transformation temperatures. SMAnalytics represents the first publicly available uniform software package for processing data generated using the DSC, UCFTC, and UPFR test methods, as well as many modifications of these methods, including loading in martensite versus austenite and performing multiple thermal cycles at stress. In doing so, it provides a tool for reducing potential error or variability in the measured values due to the precision of the technique used and person-to-person variability. It is also expected that this automated data-parsing tool can accelerate the data analysis phase of the test campaign, especially for large data files. This User’s Manual describes how the SMAnalytics software works and the method for its use.

Shape Memory Alloy↗
NASA NTRS1977

Economic Analysis in the Pacific Northwest Land Resources Project: Theoretical Considerations and Preliminary Results

The Pacific Northwest Land Resources Inventory Demonstration Project i s an a ttempt to combine a whole spectrum of heterogeneous geographic, institutional and applications elements in a synergistic approach to the evaluation of remote sensing techniques. This diversity is the prime motivating factor behind a theoretical investigation of alternative economic analysis procedures. For a multitude of reasons--simplicity, ease of understanding, financial constraints and credibility, among others--cost-effectiveness emerges as the most practical tool for conducting such evaluation determinatIons in the Pacific Northwest. Preliminary findings in two water resource application areas suggest, in conformity with most published studies, that Lands at-aided data collection methods enjoy substantial cost advantages over alternative techniques. The pntential for sensitivity analysis based on cost/accuracy tradeoffs is considered on a theoretical plane in the absence of current accuracy figures concerning the Landsat-aided approach.

Morse, D. R. A.↗
NASA NTRS1981

A four dimensional variational analysis experiment

A demonstration that the four dimensional variational analysis method using the governing equations as exact constraints can be successfully employed for a perfect model and for a simple, but nonlinear, system is presented. The method is stable in an assimilation cycle. The method reconstructs the unobservable variables; in the case demonstrated, no velocity data was observed. The analysis errors are much smaller than the observing system errors.

Hoffman, R.↗
NASA NTRS2007

The Mock LISA Data Challenges: History, Status, Prospects

This slide presentation reviews the importance for the Mock LISA Data Challenges (MLDC). Laser Interferometer Space Antenna (LISA) is a gravitational wave (GW) observatory that will return data such that data analysis is integral to the measurement concept. Further rationale of the MLDC are to kickstart the development of a LISA data-analysis computational infrastructure, and to encourage, track, and compare progress in LISA data-analysis development in the open community. The MLDCs is a coordinated, voluntary effort in GW community, that will periodically issue datasets with synthetic noise and GW signals from sources of undisclosed parameters; increasing difficulty. The challenge participants return parameter estimates and descriptions of search methods. Some of the challenges and the resultant entries are reviewed. The aim is to show that LISA data analysis is possible, and to develop new techniques, using multiple international teams for the development of LISA core analysis tools

data analysis↗
NASA NTRS1993

TransFit: Finite element analysis data fitting software

The Advanced X-Ray Astrophysics Facility (AXAF) mission support team has made extensive use of geometric ray tracing to analyze the performance of AXAF developmental and flight optics. One important aspect of this performance modeling is the incorporation of finite element analysis (FEA) data into the surface deformations of the optical elements. TransFit is software designed for the fitting of FEA data of Wolter I optical surface distortions with a continuous surface description which can then be used by SAO's analytic ray tracing software, currently OSAC (Optical Surface Analysis Code). The improved capabilities of Transfit over previous methods include bicubic spline fitting of FEA data to accommodate higher spatial frequency distortions, fitted data visualization for assessing the quality of fit, the ability to accommodate input data from three FEA codes plus other standard formats, and options for alignment of the model coordinate system with the ray trace coordinate system. TransFit uses the AnswerGarden graphical user interface (GUI) to edit input parameters and then access routines written in PV-WAVE, C, and FORTRAN to allow the user to interactively create, evaluate, and modify the fit. The topics covered include an introduction to TransFit: requirements, designs philosophy, and implementation; design specifics: modules, parameters, fitting algorithms, and data displays; a procedural example; verification of performance; future work; and appendices on online help and ray trace results of the verification section.

Freeman, Mark↗
NASA NTRS1978

Wing analysis using a transonic potential flow computational method

The ability of the method to compute wing transonic performance was determined by comparing computed results with both experimental data and results computed by other theoretical procedures. Both pressure distributions and aerodynamic forces were evaluated. Comparisons indicated that the method is a significant improvement in transonic wing analysis capability. In particular, the computational method generally calculated the correct development of three-dimensional pressure distributions from subcritical to transonic conditions. Complicated, multiple shocked flows observed experimentally were reproduced computationally. The ability to identify the effects of design modifications was demonstrated both in terms of pressure distributions and shock drag characteristics.

Henne, P. A.↗
NASA NTRS2004

Implementation of Coupled Skin Temperature Analysis and Bias Correction in a Global Atmospheric Data Assimilation System

The NASA/NCAR Finite Volume GCM (fvGCM) with the NCAR CLM (Community Land Model) version 2.0 was integrated into the NASA/GMAO Finite Volume Data Assimilation System (fvDAS). A new method was developed for coupled skin temperature assimilation and bias correction where the analysis increment and bias correction term is passed into the CLM2 and considered a forcing term in the solution to the energy balance. For our purposes, the fvDAS CLM2 was run at 1 deg. x 1.25 deg. horizontal resolution with 55 vertical levels. We assimilate the ISCCP-DX (30 km resolution) surface temperature product. The atmospheric analysis was performed 6-hourly, while the skin temperature analysis was performed 3-hourly. The bias correction term, which was updated at the analysis times, was added to the skin temperature tendency equation at every timestep. In this presentation, we focus on the validation of the surface energy budget at the in situ reference sites for the Coordinated Enhanced Observation Period (CEOP). We will concentrate on sites that include independent skin temperature measurements and complete energy budget observations for the month of July 2001. In addition, MODIS skin temperature will be used for validation. Several assimilations were conducted and preliminary results will be presented.

Radakovich, Jon↗
NASA NTRS1983

Optimal processing of satellite-derived magnetic anomaly data

It is shown how the concept of the power spectrum can be extended to two-dimensional spatial power spectra and how it can be used in determining optimal data processing methods for satellite-derived magnetic anomaly data and planning missions to obtain such data. The analysis techniques are applied to the data set and data-processing procedure described by Mayhew et al. (1980), a study that treats magnetic anomaly data for Australia and the surrounding ocean obtained by the polar orbit POGO series satellites. It is shown that the data-processing method used by Mayhew et al. is approximately equivalent to an invariant two-dimensional linear filter and that it is reasonably close to optimal with respect to accuracy, although some possible improvements are suggested. However, as is usual when filtering data, some real 'signal' is unavoidably removed along with the 'noise' resulting in errors that can be quite large. A method for reducing these errors by using additional data from a medium inclination orbit satellite (for example, 60 deg inclination) is proposed.

Mcleod, M. G.↗

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