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At least 91 records · Page 5

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NASA NTRS1972

Prototype ultrasonic instrument for quantitative testing

A prototype ultrasonic instrument has been designed and developed for quantitative testing. The complete delivered instrument consists of a pulser/receiver which plugs into a standard oscilloscope, an rf power amplifier, a standard decade oscillator, and a set of broadband transducers for typical use at 1, 2, 5 and 10 MHz. The system provides for its own calibration, and on the oscilloscope, presents a quantitative (digital) indication of time base and sensitivity scale factors and some measurement data.

Lynnworth, L. C.↗

NASA NTRS1973

Microstructural study of the nickel-base alloy WAZ-20 using qualitative and quantitative electron optical techniques

The NASA nickel-base alloy WAZ-20 was analyzed by advanced metallographic techniques to qualitatively and quantitatively characterize its phases and stability. The as-cast alloy contained primary gamma-prime, a coarse gamma-gamma prime eutectic, a gamma-fine gamma prime matrix, and MC carbides. A specimen aged at 870 C for 1000 hours contained these same constituents and a few widely scattered high W particles. No detrimental phases (such as sigma or mu) were observed. Scanning electron microscope, light metallography, and replica electron microscope methods are compared. The value of quantitative electron microprobe techniques such as spot and area analysis is demonstrated.

Young, S. G.↗

NASA NTRS1973

The use of aerial photography to quantitatively delineate mixing zones - A progress report

Aerial photography has been used to characterize and model the mixing zones which result from waste effluent discharges at seven river sites throughout the state of Wisconsin. The mixing zone is defined as the portion of the river where the waste effluent is totally mixed with the ambient receiving water. An integrated program of field sampling, mathematical modeling, laboratory modeling, and remote sensing was conducted to develop a quantitative relationship for the volumetric configuration of the mixing zone as a function of the measurable characteristics of various effluents, outfalls, and receiving water bodies. Analysis of scanning microdensitometer data extracted from 9-in. color IR transparencies has confirmed the utility of employing image density measurements to quantitatively delineate surficial concentration patterns within the mixing zone.

Lillesand, T. M.↗

NASA NTRS1975

On the quantitative evaluation of edge detection schemes and their comparison with human performance

A technique for the quantitative evaluation of edge detection schemes is presented. It is used to assess the performance of three such schemes using a specially-generated set of images containing noise. The ability of human subjects to distinguish the edges in the presence of noise is also measured and compared with that of the edge detection schemes. The edge detection schemes are used on a high-resolution satellite photograph with varying degrees of noise added in order to relate the quantitative comparison to real-life imagery.

Fram, J. R.↗

NASA NTRS1975

Quantitative suspended sediment mapping using aircraft remotely sensed multispectral data

Suspended sediment is an important environmental parameter for monitoring water quality, water movement, and land use. Quantitative suspended sediment determinations were made from analysis of aircraft remotely sensed multispectral digital data. A statistical analysis and derived regression equation were used to determine and plot quantitative suspended sediment concentration contours in the tidal James River, Virginia, on May 28, 1974. From the analysis, a single band, Band 8 (0.70-0.74 microns), was adequate for determining suspended sediment concentrations. A correlation coefficient of 0.89 was obtained with a mean inaccuracy of 23.5 percent for suspended sediment concentrations up to about 50 mg/l. Other water quality parameters - secchi disc depth and chlorophyll - also had high correlations with the remotely sensed data. Particle size distribution had only a fair correlation with the remotely sensed data.

Johnson, R. W.↗

NASA NTRS1976

Cardiovascular and pulmonary dynamics by quantitative imaging

The accuracy and range of studies on cardiovascular and pulmonary functions can be greatly facilitated if the motions of the underlying organ systems throughout individual cycles can be directly visualized and readily measured with minimum or preferably no effect on these motions. Achievement of this objective requires development of techniques for quantitative noninvasive or minimally invasive dynamic and stop-action imaging of the organ systems. A review of advances in dynamic quantitative imaging of moving organs reveals that the revolutionary value of cross-sectional and three-dimensional images produced by various types of radiant energy such as X-rays and gamma rays, positrons, electrons, protons, light, and ultrasound for clinical diagnostic and biomedical research applications is just beginning to be realized. The fabrication of a clinically useful cross-section reconstruction device with sensing capabilities for both anatomical structural composition and chemical composition may be possible and awaits future development.

Wood, E. H.↗

NASA NTRS1975

Clinical application of a light-pen computer system for quantitative angiography

The paper describes an angiographic analysis system which uses a video disk for recording and playback, a light-pen for data input, minicomputer processing, and an electrostatic printer/plotter for hardcopy output. The method is applied to quantitative analysis of ventricular volumes, sequential ventriculography for assessment of physiologic and pharmacologic interventions, analysis of instantaneous time sequence of ventricular systolic and diastolic events, and quantitation of segmental abnormalities. The system is shown to provide the capability for computation of ventricular volumes and other measurements from operator-defined margins by greatly reducing the tedium and errors associated with manual planimetry.

Alderman, E. L.↗

NASA NTRS1977

Quantitative analysis of aircraft multispectral-scanner data and mapping of water-quality parameters in the James River in Virginia

Statistical analysis techniques were applied to develop quantitative relationships between in situ river measurements and the remotely sensed data that were obtained over the James River in Virginia on 28 May 1974. The remotely sensed data were collected with a multispectral scanner and with photographs taken from an aircraft platform. Concentration differences among water quality parameters such as suspended sediment, chlorophyll a, and nutrients indicated significant spectral variations. Calibrated equations from the multiple regression analysis were used to develop maps that indicated the quantitative distributions of water quality parameters and the dispersion characteristics of a pollutant plume entering the turbid river system. Results from further analyses that use only three preselected multispectral scanner bands of data indicated that regression coefficients and standard errors of estimate were not appreciably degraded compared with results from the 10-band analysis.

Johnson, R. W.↗

NASA NTRS1979

Qualitative and quantitative flow visualization technique using ozone

The paper describes a new flow-visualization technique based on the absorption of ultraviolet light by ozone. Ozone is an excellent tracer, because as a gas it has the same effective physical properties as air. Ozone strongly absorbs the principal line (253.7 nm) of a mercury lamp, so that when an ozone-traced flow passes between a mercury lamp and a fluorescent screen, a sharp, shadow-like image of the ozone tracer is cast on the screen. Quantitative photometry can be carried out by replacing the screen with ultraviolet detectors that yield the path-integrated column density of ozone in the flow. High-speed quantitative point monitoring (10 Hz at 10 ppb O3) is possible with capillary probes and chemiluminescent analysis.

Dickerson, R. R.↗

NASA NTRS1980

Quantitative analysis of defects in silicon. Silicon sheet growth development for the large are silicon sheet task of the low-cost solar array project

One hundred and seventy four silicon sheet samples were analyzed for twin boundary density, dislocation pit density, and grain boundary length. Procedures were developed for the quantitative analysis of the twin boundary and dislocation pit densities using a QTM-720 Quantitative Image Analyzing system. The QTM-720 system was upgraded with the addition of a PDP 11/03 mini-computer with dual floppy disc drive, a digital equipment writer high speed printer, and a field-image feature interface module. Three versions of a computer program that controls the data acquisition and analysis on the QTM-720 were written. Procedures for the chemical polishing and etching were also developed.

Natesh, R.↗

NASA NTRS1980

Quantitative optical scanning tests of complex microcircuits

An approach for the development of the optical scanner as a screening inspection instrument for microcircuits involves comparing the quantitative differences in photoresponse images and then correlating them with electrical parameter differences in test devices. The existing optical scanner was modified so that the photoresponse data could be recorded and subsequently digitized. A method was devised for applying digital image processing techniques to the digitized photoresponse data in order to quantitatively compare the data. Electrical tests were performed and photoresponse images were recorded before and following life test intervals on two groups of test devices. Correlations were made between differences or changes in the electrical parameters of the test devices.

Erickson, J. J.↗

NASA NTRS1980

Quantitative interpretation of Great Lakes remote sensing data

The paper discusses the quantitative interpretation of Great Lakes remote sensing water quality data. Remote sensing using color information must take into account (1) the existence of many different organic and inorganic species throughout the Great Lakes, (2) the occurrence of a mixture of species in most locations, and (3) spatial variations in types and concentration of species. The radiative transfer model provides a potential method for an orderly analysis of remote sensing data and a physical basis for developing quantitative algorithms. Predictions and field measurements of volume reflectances are presented which show the advantage of using a radiative transfer model. Spectral absorptance and backscattering coefficients for two inorganic sediments are reported.

Shook, D. F.↗

NASA NTRS1981

A quantitative method for evaluating alternatives

When faced with choosing between alternatives, people tend to use a number of criteria (often subjective, rather than objective) to decide which is the best alternative for them given their unique situation. The subjectivity inherent in the decision-making process can be reduced by the definition and use of a quantitative method for evaluating alternatives. This type of method can help decision makers achieve degree of uniformity and completeness in the evaluation process, as well as an increased sensitivity to the factors involved. Additional side-effects are better documentation and visibility of the rationale behind the resulting decisions. General guidelines for defining a quantitative method are presented and a particular method (called 'hierarchical weighted average') is defined and applied to the evaluation of design alternatives for a hypothetical computer system capability.

Forthofer, M. J.↗

NASA NTRS1982

A method for the extraction and quantitation of phycoerythrin from algae

A summary of a new technique for the extraction and quantitation of phycoerythrin (PHE) from algal samples is described. Results of analysis of four extracts representing three PHE types from algae including cryptomonad and cyanophyte types are presented. The method of extraction and an equation for quantitation are given. A graph showing the relationship of concentration and fluorescence units that may be used with samples fluorescing around 575-580 nm (probably dominated by cryptophytes in estuarine waters) and 560 nm (dominated by cyanophytes characteristics of the open ocean) is provided.

Stewart, D. E.↗

NASA NTRS1983

Quantitative measurement of density and velocity in compressible flows using laser-induced iodine fluorescence

A nonintrusive optical technique for the quantitative measurement of molecular density and velocity at a point or in an entire cross-sectional plane of a compressible flowfield is reported. Iodine molecules, seeded into the flowfield reservoir, are excited by a tunable narrow-bandwidth laser and the resulting spatially-resolved fluorescence is collected by a single- or multiple-element detector. A theoretical model for the iodine laser-induced fluorescence process is essential for quantitative measurements and is developed using a rate-equation approach. Density measurements using laser-induced fluorescence are normally complicated by collisional quenching; however, the theory predicts that the off-resonant fluorescent signal is directly proportional to density. Velocity is directly related to the Doppler shift of the iodine absorption line, determined by monitoring the broadband fluorescent signal as the laser is tuned in frequency. Experiments in a steady supersonic flowfield are compared with numerical calculations to demonstrate the accuracy of the approach for density and velocity measurement and the lack of perturbation to the flowfield by the iodine seeding. Extensions of the current approach to density and velocity measurement in lower Mach number flows, to the measurement of pressure and temperature, and to temporally-resolved measurements are discussed.

Mcdaniel, J. C.↗

NASA NTRS1984

Quantitative non-destructive evaluation of composite materials based on ultrasonic wave propagation

The size, shape, and orientation of damage correlates well between the polar backscatter technique and the deply technique. There is good quantitative correlation between the areas of damage indicated by the two techniques. These results suggest that the polar backscatter technique is sensitive to specific orientations of damage. The polar backscatter technique provides a good qualitative image of the size and shape of the largest zone of damage in each of the principal orientations. A quantitative estimate of the extent of these largest damage zones is obtained from the polar backscatter technique. The selective sensitivity of polar backscatter provides a useful tool for further studies of the mechanisms of impact damage in graphite fiber reinforced composite laminates.

Miller, J. G.↗

NASA NTRS1984

Quantitative assessment of damage growth in graphite epoxy laminates by acousto-ultrasonic measurements

The acoustoultrasonic NDT method proposed by Vary (1976, 1978) for composite laminate damage growth quantitative assessment can both respond to the development of damage states and furnish quantitative parameters that monitor this damage development. Attention is presently given to data obtained for the case of quasi-static loading and fatigue testing of graphite-epoxy laminates. The shape parameters of the power spectral density for the ultrasonic signals correlate well with such other indications of damage development as stiffness degradation.

Talreja, R.↗

NASA NTRS1986

Quantitative Schlieren analysis applied to holograms of crystals grown on Spacelab 3

In order to extract additional information about crystals grown in the microgravity environment of Spacelab, a quantitative schlieren analysis technique was developed for use in a Holography Ground System of the Fluid Experiment System. Utilizing the Unidex position controller, it was possible to measure deviation angles produced by refractive index gradients of 0.5 milliradians. Additionally, refractive index gradient maps for any recorded time during the crystal growth were drawn and used to create solute concentration maps for the environment around the crystal. The technique was applied to flight holograms of Cell 204 of the Fluid Experiment System that were recorded during the Spacelab 3 mission on STS 51B. A triglycine sulfate crystal was grown under isothermal conditions in the cell and the data gathered with the quantitative schlieren analysis technique is consistent with a diffusion limited growth process.

Brooks, Howard L.↗