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Results for “quantitative evaluation”

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 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Feasibility of determining flat roof heat losses using aerial thermography

The utility of aerial thermography for determining rooftop heat losses was investigated experimentally using several completely instrumented test roofs with known thermal resistances. Actual rooftop heat losses were obtained both from in-situ instrumentation and aerial thermography obtained from overflights at an altitude of 305 m. In general, the remotely determined roof surface temperatures agreed very well with those obtained from ground measurements. The roof heat losses calculated using the remotely determined roof temperature agreed to within 17% of those calculated from 1/R delta T using ground measurements. However, this agreement may be fortuitous since the convective component of the heat loss is sensitive to small changes in roof temperature and to the average heat transfer coefficient used, whereas the radiative component is less sensitive. This, at this time, it is felt that an acceptable quantitative determination of roof heat losses using aerial thermography is only feasible when the convective term is accurately known or minimized. The sensitivity of the heat loss determination to environmental conditions was also evaluated. The analysis showed that the most reliable quantitative heat loss determinations can probably be obtained from aerial thermography taken under conditions of total cloud cover with low wind speeds and at low ambient temperatures.

Bowman, R. L.↗
NASA NTRS1979

Man-machine analysis of translation and work tasks of Skylab films

An objective approach to determine the concurrent validity of computer-graphic models is real time film analysis. This technique was illustrated through the procedures and results obtained in an evaluation of translation of Skylab mission astronauts. The quantitative analysis was facilitated by the use of an electronic film analyzer, minicomputer, and specifically supportive software. The uses of this technique for human factors research are: (1) validation of theoretical operator models; (2) biokinetic analysis; (3) objective data evaluation; (4) dynamic anthropometry; (5) empirical time-line analysis; and (6) consideration of human variability. Computer assisted techniques for interface design and evaluation have the potential for improving the capability for human factors engineering.

Hosler, W. W.↗
NASA NTRS2012

Calibration of Airframe and Occupant Models for Two Full-Scale Rotorcraft Crash Tests

Two full-scale crash tests of an MD-500 helicopter were conducted in 2009 and 2010 at NASA Langley's Landing and Impact Research Facility in support of NASA s Subsonic Rotary Wing Crashworthiness Project. The first crash test was conducted to evaluate the performance of an externally mounted composite deployable energy absorber under combined impact conditions. In the second crash test, the energy absorber was removed to establish baseline loads that are regarded as severe but survivable. Accelerations and kinematic data collected from the crash tests were compared to a system integrated finite element model of the test article. Results from 19 accelerometers placed throughout the airframe were compared to finite element model responses. The model developed for the purposes of predicting acceleration responses from the first crash test was inadequate when evaluating more severe conditions seen in the second crash test. A newly developed model calibration approach that includes uncertainty estimation, parameter sensitivity, impact shape orthogonality, and numerical optimization was used to calibrate model results for the second full-scale crash test. This combination of heuristic and quantitative methods was used to identify modeling deficiencies, evaluate parameter importance, and propose required model changes. It is shown that the multi-dimensional calibration techniques presented here are particularly effective in identifying model adequacy. Acceleration results for the calibrated model were compared to test results and the original model results. There was a noticeable improvement in the pilot and co-pilot region, a slight improvement in the occupant model response, and an over-stiffening effect in the passenger region. This approach should be adopted early on, in combination with the building-block approaches that are customarily used, for model development and test planning guidance. Complete crash simulations with validated finite element models can be used to satisfy crash certification requirements, thereby reducing overall development costs.

Annett, Martin S.↗
NASA NTRS1985

Four applications of a software data collection and analysis methodology

The evaluation of software technologies suffers because of the lack of quantitative assessment of their effect on software development and modification. A seven-step data collection and analysis methodology couples software technology evaluation with software measurement. Four in-depth applications of the methodology are presented. The four studies represent each of the general categories of analyses on the software product and development process: blocked subject-project studies, replicated project studies, multi-project variation studies, and single project strategies. The four applications are in the areas of, respectively, software testing, cleanroom software development, characteristic software metric sets, and software error analysis.

Basili, Victor R.↗
NASA NTRS1974

Rhythmic variation in heart rate and respiration rate during space flight - Apollo 15

As part of the operational biomedical monitoring for Apollo manned missions, ECG and respiration rate are telemetered at selected intervals to mission control. The data were collected as part of this monitoring program. These data were evaluated for circadian and ultradian rhythmicity because of their uniqueness. The ability to detect and quantitate biorhythms in living systems during space flight is an important aspect of evaluating hypotheses concerning the underlying mechanisms of these phenomena. Circadian variation in heart rate during space flight is demonstrated here. In analyzing generated time series data it has been found that period discrimination is much better than the theoretical limit.

Rummel, J. A.↗
NASA NTRS2000

NIST Efforts to Quality-Assure Gunpowder Measurements

In the past few years, the National Institute for Standards and Technology (NIST) has been promoting the idea of quantitatively determining the additives in smokeless gunpowder using micellar capillary electrophoresis as a means of investigating the criminal use of hand guns and pipe bombs. As a part of this effort, we have evaluated both supercritical fluid and ultrasonic solvent extractions for the quantitative recovery of nitroglycerin (NG), diphenylamine (DPA), N-nitrosodiphenylamine (NnDPA), and ethyl centralite (EC) from gunpowder. Recoveries were evaluated by repeat extraction and matrix spiking experiments. The final extraction protocol provides greater than 95 percent recoveries. To help other researches validate their own analytical method for additive determinations, NIST is exploring the development of a standard reference material, Additives in Smokeless Gunpowder. The evaluated method is being applied to two double-base (NG-containing) powders, one stabilized with diphenylamine and the other with ethyl centralite. As part of this reference material development effort, we are conducting an interlaboratory comparison exercise among the forensic and military gunpowder measurement community.

MacCrehan, William A.↗
NASA NTRS1975

Results from the crop identification technology assessment for remote sensing /CITARS/ project

The CITARS (Crop Identification Technology Assessment for Remote Sensing) task design, objectives, and results are reviewed along with relevant conclusions and recommendations. The principal assessment concern crop identification performance for corn and soybeans in six sites in Illinois and Indiana. Use of quantitative measures of classification performance and statistical evaluations of the results have been important parts of the technology assessment. Relation of crop and sensor characteristics is discussed. Factors affecting crop identification performance are identified as crop maturity and site characteristics, type of single-date automatic data processing procedure used for local recognition, nonlocal recognition with and without processing for extension of recognition signatures, and use of multidate or multitemporal data. In particular, the probability of correct classification of field center pixels is not well correlated and thus is not a reliable indicator of proportion estimation performance.

Bizzell, R. M.↗
NASA NTRS1977

Vectorcardiographic results from Skylab medical experiment M092: Lower body negative pressure

Electrocardiographic interval changes suggesting effects of increased vagal tone were observed early in some Gemini crewmembers. Preflight versus postflight amplitude differences appeared in electrocardiograms of several of the early Apollo crewmembers. In preflight and postflight crew evaluations of the last three Apollo flights, quantitative postflight vectorcardiographic changes were for the first time determined in American space crews. Changes not considered related to heart rate were mainly those of increased P and QRS vector magnitudes and orientation shifts. But since most of these postflight findings resembled those observed with the orthostatic stress of lower body negative pressure, it was inferred then that upon their return from space, these Apollo astronauts exhibited exaggerated responses to orthostasis in the vectorcardiogram as well as in measures of cardiovascular hemodynamics.

Hoffler, G. W.↗
NASA NTRS1976

Image processing system performance prediction and product quality evaluation

The author has identified the following significant results. A new technique for image processing system performance prediction and product quality evaluation was developed. It was entirely objective, quantitative, and general, and should prove useful in system design and quality control. The technique and its application to determination of quality control procedures for the Earth Resources Technology Satellite NASA Data Processing Facility are described.

Stein, E. K.↗
NASA NTRS1977

Postural equilibrium following exposure to weightless space flight

Postural equilibrium performance by Skylab crewmen following exposure to weightlessness of 28, 59, and 84 days respectively was evaluated using a modified version of a quantitative ataxia test developed by Graybiel and Fregly (1966). Performance for this test was measured under two sets of conditions. In the first, the crewman was required to maintain postural equilibrium on narrow metal rails (or floor) with his eyes open. In the second condition, he attempted to balance with his eyes closed. A comparison of the preflight and postflight data indicated moderate postflight decrements in postural equilibrium in three of the crewmen during the eyes open test condition. In the eyes-closed condition, a considerable decrease in ability to maintain balance on the rails was observed postflight for all crewmen tested. The magnitude of the change was most pronounced during the first postflight test day. Improvement was slow; however, on the basis of data obtained, recovery of preflight baseline levels of performance was evidently complete at the end of approximately two weeks for all crewmen. The findings are explained in terms of functional alterations in the kinesthetic, touch, vestibular and neuromuscular sensory mechanisms induced by the prolonged absence of a normal 1-G gravitational environment.

Homick, J. L.↗
NASA NTRS1988

Input-output characterization of fiber composites by SH waves

Input-output characterization of fiber composites is studied theoretically by tracing SH waves in the media. A fiberglass epoxy composite is modeled as a homogeneous transversely isotropic continuum plate. The reflection of an SH wave at a stress-free plane boundary in a semi-infinite transversely isotropic medium is considered first. It is found that an incident SH wave reflects only a similar SH wave back into the medium. It is also established that the angle of reflection of the reflected wave is equal to the angle of incidence of the incident wave. The phase velocity of the SH waves and the delay time of the SH waves in reaching the receiving transducer are computed as functions of a reflection index, defined as the number of reflections of the SH waves from the bottom face of the continuum plate. The directivity function corresponding to the shear stress associated with the SH waves in the continuum plate is also derived as a function of the reflection index. A theoretical output voltage from the receiving transducer is calculated for a tone burst (a periodic input voltage of finite duration). The output voltage is shown for tone bursts of duration 60 microseconds and center frequencies of 0.75, 1.00, and 1.25 MHz. The study enhances the quantitative and qualitative understanding of the nondestructive evaluation (NDE) of fiber composites which can be modeled as transversely isotropic media.

Renneisen, John D.↗
NASA NTRS1988

The quantitative modelling of human spatial habitability

A theoretical model for evaluating human spatial habitability (HuSH) in the proposed U.S. Space Station is developed. Optimizing the fitness of the space station environment for human occupancy will help reduce environmental stress due to long-term isolation and confinement in its small habitable volume. The development of tools that operationalize the behavioral bases of spatial volume for visual kinesthetic, and social logic considerations is suggested. This report further calls for systematic scientific investigations of how much real and how much perceived volume people need in order to function normally and with minimal stress in space-based settings. The theoretical model presented in this report can be applied to any size or shape interior, at any scale of consideration, for the Space Station as a whole to an individual enclosure or work station. Using as a point of departure the Isovist model developed by Dr. Michael Benedikt of the U. of Texas, the report suggests that spatial habitability can become as amenable to careful assessment as engineering and life support concerns.

Wise, James A.↗
NASA NTRS1990

Input-output characterization of fiber reinforced composites by P waves

Input-output characterization of fiber composites is studied theoretically by tracing P waves in the media. A new path motion to aid in the tracing of P and the reflection generated SV wave paths in the continuum plate is developed. A theoretical output voltage from the receiving transducer is calculated for a tone burst. The study enhances the quantitative and qualitative understanding of the nondestructive evaluation of fiber composites which can be modeled as transversely isotropic media.

Renneisen, John D.↗
NASA NTRS1989

NDE in aerospace - Requirements for science, sensors and sense

The complexity of modern nondestructive evaluation (NDE) arises from four main factors: quantitative measurement science, physical models for computational analysis, realistic interfacing with engineering decisions, and direct access to management priorities. Recent advances in the four factors of NDE are addressed. Physical models of acoustic propagation are presented that have led to the development of measurement technologies advancing the ability to assure that materials and structures will perform as designed. In addition, a brief discussion is given of current research for future mission needs such as smart structures that sense their own health. Such advances permit projects to integrate design for inspection into their plans, bringing NDE into engineering and management priorities. The measurement focus is on ultrasonics with generous case examples. Problem solutions highlighted include critical stress in fasteners, residual stress in steel, NDE laminography, and solid rocket motor NDE.

Heyman, Joseph S.↗
NASA NTRS1991

Development of a figure-of-merit for space missions

The concept of a quantitative figure-of-merit (FOM) to evaluate different and competing options for space missions is further developed. Over six hundred individual factors are considered. These range from mission orbital mechanics to in-situ resource utilization (ISRU/ISMU) plants. The program utilizes a commercial software package for synthesis and visual display; the details are completely developed in-house. Historical FOM's are derived for successful space missions such as the Surveyor, Voyager, Apollo, etc. A cost FOM is also mentioned. The bulk of this work is devoted to one specific example of Mars Sample Return (MSR). The program is flexible enough to accommodate a variety of evolving technologies. Initial results show that the FOM for sample return is a function of the mass returned to LEO, and that missions utilizing ISRU/ISMU are far more cost effective than those that rely on all earth-transported resources.

Preiss, Bruce↗
NASA NTRS1992

Structural analysis of an NDE-inspected carbon-carbon component

In this research, it is demonstrated that the integration of nondestructive evaluation with the finite element method (a quantitative NDE/FEM approach) can be used for analysis and behavior prediction of advanced materials, such as fiber composites, after processing and during in-service testing. First, stress, strain, and energy data were calculated by the finite element method for square plates with a 10 percent difference in the material properties between specified segments, i.e., between the center and the outside section or between two halves of the plate. This demonstrated the efficiency of the method in predicting variations in the structural behavior based on small material property differences. Then, finite element analyses and actual axial compression tests were performed on a Space Shuttle brake stator made from woven carbon-carbon composites. The material properties used in the numerical modeling of the stator were previously characterized at a large number of points on the component by quantitative NDE-procedures, i.e., ultrasonics and radiography. The results from the experimental compressive loading tests were used to verify the NDE/FEM results. Good agreement was found for most parameters.

Striz, A. G.↗
NASA NTRS2000

NASA's New Approach for Evaluating Risk Reduction Due to Space Shuttle Upgrades

As part of NASA's intensive effort to incorporate quantitative risk assessment (QRA) tools in the Agency's decision-making process concerning Space Shuttle risk, NASA has developed a powerful risk assessment tool called the Quantitative Risk Assessment System (QRAS). The QRAS is a tool designed to estimate Space Shuttle risk and evaluate Space Shuttle upgrades. This paper presents an overview of the QRAS with focus on its application for evaluating the risk reduction due to proposed Space Shuttle upgrades. The application includes a case study from the Space Shuttle main engine (SSME). The QRAS overview section of the paper includes the QRAS development process, the technical approach to model development, the QRA quantification methods and techniques, and observations concerning the complex modeling involved in QRAS. The application section of the paper describes a practical case study using QRAS models for evaluating critical Space Shuttle Program upgrades, specifically a proposed SSME nozzle upgrade. This paper presents the method for evaluating the proposed upgrade by comparing the current nozzle (old design with well-established probabilistic models) to the channel wall nozzle (new design at the preliminary design level).

Safie, Fayssal M.↗