Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Functional data analysis”

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 1,027 records · Page 57
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

Analysis of the shearout failure mode in composite bolted joints

A semi-empirical shearout strength model has been formulated for the analysis of composite bolted joints with allowance for the effects of joint geometry. The model employs a polynomial stress function in conjunction with a point stress failure criterion to predict strength as a function of fastener size, edge distance, and half spacing. The stress function is obtained by two-dimensional plane-stress finite element analysis using quadrilateral elements with orthotropic material properties. Comparison of experimentally determined shearout strength data with model predicted failures has substantiated the accuracy of the model.

Wilson, D. W.↗
NASA NTRS1985

Preliminary Evaluation of Thematic Mapper Image Data Quality

Improvements in the ability to monitor renewable resources/vegegation due to improvements in the spatial, spectral and radiometric resolution of TM data were evaluated. Results presented from the first 4 months of analysis presented include: (1) geometric performance; (2) band-to-band registration; (3) modulation transfer function; and (4) crop separabililty performance. Crop separability in Webster County, Iowa and in Mississippi County, Arkansas as determined by cluster and principal components analyses is assessed.

Macdonald, R. B.↗
NASA NTRS1985

Measurement and Modeling of the Optical Scattering Properties of Crop Canopies

The specular reflection process is shown to be a key aspect of radiation transfer by plant canopies. Polarization measurements are demonstrated as the tool for determining the specular and diffuse portions of the canopy radiance. The magnitude of the specular fraction of the reflectance is significant compared to the magnitude of the diffuse fraction. Therefore, it is necessary to consider specularly reflected light in developing and evaluating light-canopy interaction models for wheat canopies. Models which assume leaves are diffuse reflectors correctly predict only the diffuse fraction of the canopy reflectance factor. The specular reflectance model, when coupled with a diffuse leaf model, would predict both the specular and diffuse portions of the reflectance factor. The specular model predicts and the data analysis confirms that the single variable, angle of incidence of specularly reflected sunlight on the leaf, explains much of variation in the polarization data as a function of view-illumination directions.

Vanderbilt, V. C.↗
NASA NTRS1988

Telescience testbedding for life science missions on the Space Station

'Telescience', defined as the ability of distributed system users to perform remote operations associated with NASA Space Station life science operations, has been explored by a developmental testbed project allowing rapid prototyping to evaluate the functional requirements of telescience implementation in three areas: (1) research planning and design, (2) remote operation of facilities, and (3) remote access to data bases for analysis. Attention is given to the role of expert systems in telescience, its use in realistic simulation of Space Shuttle payload remote monitoring, and remote interaction with life science data bases.

Rasmussen, D.↗
NASA NTRS1990

FACE computer simulation

A computer simulation of the FACE (Flexible Arm Controls Experiment) was conducted to assess its design for use in the Space Shuttle. The FACE is supposed to be a 14-ft long articulate structure with 4 degrees of freedom, consisting of shoulder pitch and yaw, elbow pitch, and wrist pitch. Kinematics of the FACE was simulated to obtain data on arm operation, function, workspace and interaction. Payload capture ability was modeled. The simulation indicates the capability for detailed kinematic simulation and payload capture ability analysis, and the feasibility of real-time simulation was determined. In addition, the potential for interactive real-time training through integration of the simulation with various interface controllers was revealed. At this stage, the flexibility of the arm was not yet considered.

Sadeh, Willy Z.↗
NASA NTRS1991

ADDRAS - An integrated systems approach

NASA-Langley's Acoustics Division Data Reduction and Analysis System (ADDRAS) computes far-field noise spectral estimates on the basis of weather, aircraft state and position, and acoustic data sets. The structure and function of ADDRAS has been primarily determined by rotorcraft flyover test design, data acquisition, and data flow criteria. The RIM relational database management software is used to organize all noise test data for ADDRAS.

Becker, Lawrence E.↗
NASA NTRS1993

Cross-correlation between the 170 GHz survey map and the COBE differential microwave radiometer first-year maps

This letter describes results of a cross-correlation between the 170 GHz partial-sky survey, made with a 3.8 deg beam balloon-borne instrument, and the COBE DMR 'Fit Technique' reduced galaxy all-sky map with a beam of 7 deg. The strong correlation between the data sets implies that the observed structure is consistent with thermal variations in a 2.7 K emitter. A chi-square analysis applied to the correlation function rules out the assumption that there is no structure in either of the two maps. A second test shows that if the DMR map has structure but the 170 GHz map does not, the probability of obtaining the observed correlation is small. Further analyses support the assumption that both maps have structure and that the 170 GHz-DMR cross-correlation is consistent with the analogous DMR correlation function. Maps containing various combinations of noise and Harrison-Zel'dovich power spectra are simulated and correlated to reinforce the result. The correlation provides compelling evidence that both instruments have observed fluctuations consistent with anisotropies in the cosmic microwave background.

Ganga, Ken↗
NASA NTRS1993

Functional approximation using artificial neural networks in structural mechanics

The artificial neural networks (ANN) methodology is an outgrowth of research in artificial intelligence. In this study, the feed-forward network model that was proposed by Rumelhart, Hinton, and Williams was applied to the mapping of functions that are encountered in structural mechanics problems. Several different network configurations were chosen to train the available data for problems in materials characterization and structural analysis of plates and shells. By using the recall process, the accuracy of these trained networks was assessed.

Alam, Javed↗
NASA NTRS1995

Optoelectronic Particle-Fallout Sensor

Portable optoelectronic system monitors fallout of small particles (dust and fibers) onto surface at given location during extended time. Data on accumulated fallout downloaded from system to computer for display and analysis. Typical display is plot of signal proportional to amount of accumulated fallout as function of time and read to determine when contamination occurs. In many cases, possible to establish correlations between accumulations of particles and activities in vicinity. Also capable of signaling alarm in event contamination by fallout exceeds specified level. System made very inexpensively and used to monitor accumulation of dust and fibers associated with motion of air in variety of environments. Phenomena monitored indirectly by use of system might include circulation of air in buildings, and human and animal activity. Also serves as auxiliary intrusion monitor (though probably not real-time alarm) in sealed room because motion of intruder inevitably stirs up some dust.

Ihlefeld, Curtis↗
NASA NTRS2000

Planning and Processing Space Science Observations Using NASA's SPICE System

The Navigation and Ancillary Information Facility (NAIF) team, acting under the directions of NASA's Office of Space Science, has built a data system-named SPICE, to assist scientists in planning and interpreting scientific observations from space-borne instruments. The principal objective of this data system is that it will provide geometric and other ancillary data used to plan space science missions and subsequently recover the full value of science instrument data returned from these missions, including correlation of individual instrument data sets with data from other instruments on the same or other spacecraft. SPICE is also used to support a host of mission engineering functions, such as telecommunications system analysis and operation of NASA's Deep Space Network antennas. This paper describes the SPICE system, including where and how it is used. It also touches on possibilities for further development and invites participation it this endeavor.

Acton, Charles H.↗
NASA NTRS2006

Assisting Public Organizations in Their Outsourcing Endeavors: A Decision Support Mode

There has been a tremendous growth in outsourcing practices in recent years. The public organizations in the United States have outsourced some functions and are now being compelled to outsource additional ones. While there are numerous studies that document and analyze outsourcing practices, there is limited research to guide public or governmental organizations in determining what functions to outsource. This study fills this gap by developing a decision support model for a typical public organization in determining what to outsource and how. A set of outsourcing decision factors is identified that can be used as parameters in the three integer programming formulations developed. These formulations are used as solution engines in the model. The first formulation identifies which functions are the best candidates for outsourcing given the organization's priorities. The other formulations place the functions into recommended contracts and re-assign displaced employees. Data from NASA Glenn Research Center in Ohio is used to test and analyze the model. Analysis indicates that cost and skills-related factors are the most sensitive parameters for the data tested. The model and the formulations are a relatively comprehensive package and may help guide outsourcing decisionmakers and policymakers in public organizations.

Kremic, TIbor↗
NASA NTRS2010

Blunt-Body Entry Vehicle Aerothermodynamics: Transition and Turbulence on the CEV and MSL Configurations

Recent, current, and planned NASA missions that employ blunt-body entry vehicles pose aerothermodynamic problems that challenge the state-of-the art of experimental and computational methods. The issues of boundary-layer transition and turbulent heating on the heat shield have become important in the designs of both the Mars Science Laboratory and Crew Exploration Vehicle. While considerable experience in these general areas exists, that experience is mainly derived from simple geometries; e.g. sharp-cones and flat-plates, or from lifting bodies such as the Space Shuttle Orbiter. For blunt-body vehicles, application of existing data, correlations, and comparisons is questionable because an all, or mostly, subsonic flow field is produced behind the bow shock, as compared to the supersonic (or even hypersonic) flow of other configurations. Because of the need for design and validation data for projects such as MSL and CEV, many new experimental studies have been conducted in the last decade to obtain detailed boundary-layer transition and turbulent heating data on this class of vehicle. In this paper, details of several of the test programs are reviewed. The laminar and turbulent data from these various test are shown to correlate in terms of edge-based Stanton and Reynolds number functions. Correlations are developed from the data for transition onset and turbulent heating augmentation as functions of momentum thickness Reynolds number. These correlation can be employed as engineering-level design and analysis tools.

Hollis, Brian R.↗
NASA NTRS2011

The Transitional Protoplanetary Disk Frequency as a Function of Age: Disk Evolution in the Coronet Cluster, Taurus, and Other 1--8 Myr-old Regions

We present Spitzer 3.6-24 micron photometry and spectroscopy for stars in the 1-3 Myr-old Coronet Cluster, expanding upon the survey of Sicilia-Aguilar et al. (2008). Using sophisticated radiative transfer models, we analyze these new data and those from Sicilia-Aguilar et al. (2008) to identify disks with evidence for substantial dust evolution consistent with disk clearing: transitional disks. We then analyze data in Taurus and others young clusters - IC 348, NGC 2362, and eta Cha -- to constrain the transitional disk frequency as a function of time. Our analysis confirms previous results finding evidence for two types of transitional disks -- those with inner holes and those that are homologously depleted. The percentage of disks in the transitional phase increases from approx.15-20% at 1-2 Myr to > 50% at 5-8 Myr; the mean transitional disk lifetime is closer to approx. 1 Myr than 0.1-0.5 Myr, consistent with previous studies by Currie et al. (2009) and Sicilia-Aguilar et al. (2009). In the Coronet Cluster and IC 348, transitional disks are more numerous for very low-mass M3--M6 stars than for more massive K5-M2 stars, while Taurus lacks a strong spectral type-dependent frequency. Assuming standard values for the gas-to-dust ratio and other disk properties, the lower limit for the masses of optically-thick primordial disks is Mdisk approx. 0.001-0.003 M*. We find that single color-color diagrams do not by themselves uniquely identify transitional disks or primordial disks. Full SED modeling is required to accurately assess disk evolution for individual sources and inform statistical estimates of the transitional disk population in large samples using mid-IR colors.

Currie, Thayne↗
NASA NTRS2011

Defining Tolerance: Impacts of Delay and Disruption when Managing Challenged Networks

Challenged networks exhibit irregularities in their communication performance stemming from node mobility, power constraints, and impacts from the operating environment. These irregularities manifest as high signal propagation delay and frequent link disruption. Understanding those limits of link disruption and propagation delay beyond which core networking features fail is an ongoing area of research. Various wireless networking communities propose tools and techniques that address these phenomena. Emerging standardization activities within the Internet Research Task Force (IRTF) and the Consultative Committee for Space Data Systems (CCSDS) look to build upon both this experience and scalability analysis. Successful research in this area is predicated upon identifying enablers for common communication functions (notably node discovery, duplex communication, state caching, and link negotiation) and how increased disruptions and delays affect their feasibility within the network. Networks that make fewer assumptions relating to these enablers provide more universal service. Specifically, reliance on node discovery and link negotiation results in network-specific operational concepts rather than scalable technical solutions. Fundamental to this debate are the definitions, assumptions, operational concepts, and anticipated scaling of these networks. This paper presents the commonalities and differences between delay and disruption tolerance, including support protocols and critical enablers. We present where and how these tolerances differ. We propose a set of use cases that must be accommodated by any standardized delay-tolerant network and discuss the implication of these on existing tool development.

mobility drivers↗
NASA NTRS2019

Analysis of Shockwave Radiation Data in Nitrogen

Data from a pure nitrogen test series in the Electric Arc Shock Tube Facility were previously reported for velocities spanning 6-12 km/s at a free-stream pressure of 0.2 Torr. This test series provides validation data for a range of physical phenomena to investigate, including vibrational relaxation, molecular radiation, nitrogen dissociation and ionization, and atomic radiation and ionization. This paper details analysis of data obtained at a nominal velocity of 10.3 km/s. The spectra are analyzed to extract temperatures and the densities of excited states as a function of position behind the shock. The effect of different methods for calculating state populations and ionization processes is assessed, as is a rigorous assessment of the atomic line lists, with both missing and extra lines identified.

Nitrogen↗
NASA NTRS2019

A Chromaticity Analysis and PSF Subtraction Techniques for SCExAO/CHARIS Data

We present an analysis of instrument performance using new observations taken with the Coronagraphic High Angular Resolution Imaging Spectrograph (CHARIS) instrument and the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) system. In a correlation analysis of our data sets (which use the broadband mode covering the J band through the K band in a single spectrum), we find that chromaticity in the SCExAO/CHARIS system is generally worse than temporal stability. We also develop a point-spread function (PSF) subtraction pipeline optimized for the CHARIS broadband mode, including a forward modeling-based exoplanet algorithmic throughput correction scheme. We then present contrast curves using this newly developed pipeline. An analogous subtraction of the same data sets using only the H-band slices yields the same final contrasts as the full JHK sequences; this result is consistent with our chromaticity analysis, illustrating that PSF subtraction using spectral differential imaging (SDI) in this broadband mode is generally not more effective than SDI in the individual J, H, or K bands. In the future, the data processing framework and analysis developed in this paper will be important to consider for additional SCExAO/CHARIS broadband observations and other ExAO instruments which plan to implement a similar integral field spectrograph broadband mode.

Benjamin L. Gerard↗
NASA NTRS2011

Temporal mapping and analysis

A compositing process for selecting spatial data collected over a period of time, creating temporal data cubes from the spatial data, and processing and/or analyzing the data using temporal mapping algebra functions. In some embodiments, the temporal data cube is creating a masked cube using the data cubes, and computing a composite from the masked cube by using temporal mapping algebra.

O'Hara, Charles G.↗
NASA NTRS1993

Development of BEM for ceramic composites

BEST-CMS (boundary element solution technology - composite modeling system) is an advanced engineering system for the micro-analysis of fiber composite structures. BEST-CMS is based upon the boundary element program BEST3D which was developed for NASA by Pratt and Whitney Aircraft and the State University of New York at Buffalo under contract NAS3-23697. BEST-CMS presently has the capabilities for elastostatic analysis, steady-state and transient heat transfer analysis, steady-state and transient concurrent thermoelastic analysis, and elastoplastic and creep analysis. The fibers are assumed to be perfectly bonded to the composite matrix, or in the case of static or steady-state analysis, the fibers may be assumed to have spring connections, thermal resistance, and/or frictional sliding between the fibers and the composite matrix. The primary objective of this user's manual is to provide an overview of all BEST-CMS capabilities, along with detailed descriptions of the input data requirements. In the next chapter, a brief review of the theoretical background is presented for each analysis category. Then, chapter three discusses the key aspects of the numerical implementation, while chapter four provides a tutorial for the beginning BEST-CMS user. The heart of the manual, however, is in chapter five, where a complete description of all data input items is provided. Within this chapter, the individual entries are grouped on a functional basis for a more coherent presentation. Chapter six includes sample problems and should be of considerable assistance to the novice. Chapter seven includes capsules of a number of fiber-composite analysis problems that have been solved using BEST-CMS. This chapter is primarily descriptive in nature and is intended merely to illustrate the level of analysis that is possible within the present BEST-CMS system. Chapter eight contains a detail description of the BEST-CMS Neutral File which is helpful in writing an interface between BEST-CMS and any graphic post-processor program. Finally, all pertinent references are listed in chapter nine.

Henry, D. P.↗