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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 1,711 records · Page 95
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Sound and fluctuating disturbance measurements in the settling chamber and test section of a small, Mach 5 wind tunnel

Disturbance measurements were made using a hot-wire anemometer and piezoelectric pressure transducers in the settling chamber and free stream of a small Mach 5 wind tunnel. Results from the two instruments are compared and acoustical disturbances in the settling chamber are discussed. The source of the test-section noise is identified as nozzle-wall waviness at low Reynolds numbers and as eddy-Mach-wave radiation from the turbulent boundary layer on the nozzle wall at high Reynolds numbers.

Anders, J. B.↗
NASA NTRS1975

Design of an optical fiber cable link for lightning instrumentation

A lightning instrumentation system was designed to record current magnitudes of lightning strikes that hit a launch pad service structure at NASA's Kennedy Space Center. The instrumentation system consists of a lightning ground rod with a current sensor coil, an optical transmitter, an optical fiber cable link, a detector receiver, and a recording system. The transmitter is a wideband pulse transformer driving an IR LED emitter. The transmitter operates linearly as a transducer. A low loss fiber bundle provides isolation of the recorder system from the electromagnetic field of the lightning strike. The output of an optical detector receiver module is sampled and recorded in digital format. The significant factors considered in the design were dynamic range, linearity, mechanical configuration, electromagnetic isolation, and temperature compensation.

Grove, C. H.↗
NASA NTRS1976

Ballistic range experiments on superbooms generated by refraction

The enhanced sonic boom or supersonic boom generated as a result of atmospheric refraction in threshold Mach number flights was recreated in a ballistic range by firing projectiles at low supersonic speeds into a stratified medium obtained by slowly injecting carbon dioxide into air. The range was equipped with a fast-response dynamic pressure transducer and schlieren photographic equipment, and the sound speed variation with height was controlled by regulating the flow rate of the CO2. The schlieren observations of the resulting flow field indicate that the generated shocks are reflected near the sonic cutoff altitude where local sound speed equals body speed, provided such an altitude exists. Maximum shock strength occurs very nearly at the point where the incident and reflected shocks join, indicating that the presence of the reflected shock may have an appreciable effect on the magnitude of the focus factor. The largest focus factor detected was 1.7 and leads to an estimate that the constant in the Guiraud-Thery scaling law should have a value of 1.30.

Sanai, M.↗
NASA NTRS1976

Mechanical testing - In situ fracture device for Auger electron spectroscopy

An in situ fracture device for Auger spectroscopy is described. The device is designed to handle small tensile specimens or small double-cantilever beam specimens and is fully instrumented with load and displacement transducers so that quantitative stress-strain measurements can be made directly. Some initial test results for specimens made from 4130 and 1020 steel are presented. Results indicate that impurity segregation at interfaces other than grain boundary may play a significant role in the mechanism of ductile fracture.

Moorhead, R. D.↗
NASA NTRS1975

Surface lubrication of magnetic tape

Friction minimization between magnetic media (tape, cards, drums, etc.) and magnetic transducer (heads, etc.) is a key requirement in recording systems. Results are presented for an investigation intended to eliminate previously encountered shortcomings of friction-reducing treatments by a deposition of an inert liquid film on a fully manufactured (cured) magnetic medium. The film contains no particles, represents a compound characterized by good lubricating and thermal properties, is inert with respect to the normal formulation constituents, and has low surface tension and vapor pressure characteristics. The deposited film need only be molecularly thin to impart adequate lubricating properties to the tape. The discussion covers the characteristics of the surface lubricant, method of application, and surface coated magnetic media test results. Greater than 5 million passes of the 3M 900 tape on a loop tester are achieved with no apparent effect on the tape and with head wear decreased by as much as a factor of ten

Wright, C. D.↗
NASA NTRS1975

Tape tracking and handling for magnetic tape recorders

One of the critical performance and life limiting elements of a spacecraft tape recorder instrumentation system which has received little attention in technical literature is magnetic tape tracking and handling technology. This technology is required to understand how to gently transfer tape from one reel to another with proper alignment and a desirable uniform velocity at the read and write transducer heads. The increased demand for high data rate (i.e., multi-track spacecraft recording instrumentation systems), coupled with performance under extreme environmental conditions, requires a thorough knowledge of the various parameters which establish an optimum designed tape tracking and handling system. Stress analysis techniques are required to evaluate these parameters substantiated with test tape tracking data, to show the effect of each parameter on a tape recorder instrumentation tracking system. The technology is applicable to ground type tape recorders where the detrimental effects of edge guidance can be eliminated.

Paroby, W.↗
NASA NTRS1977

Batteryless implanted echosonometer

Miniature ultrasonic echosonometer implanted within laboratory animals obtains energy from RF power oscillator that is electronically transduced via induction loop to power receiving loop located just under animal's skin. Method of powering device offers significant advantages over those in which battery is part of implanted package.

Kojima, G. K.↗
NASA NTRS1978

Multipurpose miniature drag-force anemometer

Simple, rugged, accurate probe measures steady-state and dynamic flow angle, and turbulence intensity in flowing fluids at subsonic velocity. Probe is simpler in design and calibration, and more durable, than hot-wire and hot-film anemometers and is not affected by flow contamination. It is less expensive and complex than laser anemometers. Associated electronics are as simple as those of strain-gage pressure transducers.

Fralick, G. C.↗
NASA NTRS1978

Particle-impact noise detector (PIND)

Package, in page assembly, is subjected to low-frequency vibration, and noise generated by particle impacts is picked up by transducer. Test procedure calls for three transverse shocks to be applied to page to dislodge any trapped particles.

Barr, R. J.↗
NASA NTRS1978

Apparatus for determining surface tension

System for studying capillary action uses pressure transducer and chart recorder instead of manometer. Apparatus enables measurements to be made under controlled atmospheres. It also may be remotely operated. These features are particularly useful when dealing with noxious liquids and for study of surface tension under high-pressure conditions that require use of all-metal apparatus.

Razouk, R. E.↗
NASA NTRS1976

Development of signal processing algorithms for ultrasonic detection of coal seam interfaces

A pattern recognition system is presented for determining the thickness of coal remaining on the roof and floor of a coal seam. The system was developed to recognize reflected pulse echo signals that are generated by an acoustical transducer and reflected from the coal seam interface. The flexibility of the system, however, should enable it to identify pulse-echo signals generated by radar or other techniques. The main difference being the specific features extracted from the recorded data as a basis for pattern recognition.

Purcell, D. D.↗
NASA NTRS1976

Biomedical technology transfer: Applications of NASA science and technology

The major efforts of the Stanford Biomedical Applications Team Program at the Stanford University School of Medicine for the period from October 1, 1975 to September 31, 1976 are covered. A completed EMG biotelemetry system which monitors the physiological signals of man and animals in space related research is discussed. The results of a pilot study involving lower body negative pressure testing in cardiac patients has been completed as well as the design and construction of a new leg negative pressure unit for evaluating heart patients. This technology utilizes vacuum chambers to stress the cardiovascular system during space flight. Laboratory tests of an intracranial pressure transducer, have been conducted. Extremely stable long term data using capacative pressure sensors has lead to the order of commercially manufactured monitoring systems base. Projects involving commercialization are: flexible medical electrodes, an echocardioscope, a miniature biotelemetry system, and an on-line ventricular contour detector.

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NASA NTRS1975

Tutorial: angiocardiography, past and present

The contribution of X-ray methodology and angiocardiography in the ability to study cardiac and cardiovascular function is presented. Angiocardiography remains the most reliable method for determination of overall chamber size and shape particularly in the face of disease states of varying etiologies. It also presents the most accurate means for obtaining dimensional information concerning the heart and blood vessels without the use of surgery or attachment of transducers.

Sandler, H.↗
NASA NTRS1975

Assessment of left ventricular ejection fraction by radionuclide angiography. Comparison to echocardiography and serial measurements in patients with myocardial infarction

Measurements of the left ventricular ejection fraction were compared in patients with previous myocardial infarctions. Left ventricular ejection fraction was measured by the radioisotopic method serially in patients early after an acute myocardial infarction and during the convalescence period. Ultrasound recordings were obtained utilizing a commercially available ultrasonoscope and a 1/9 cm transducer focused at 10 cm with a repetition rate of 1000 impulses per second. All recordings were made on a visicorder oscillography.

Schelbert, H. R.↗
NASA NTRS1975

The Stanford-Ames portable echocardioscope: A case study in technology transfer

A battery powered echocardioscope is described which was clinically validated on both normal subjects and patients. Its single hand held transducer provides a one dimensional image of the moving cardiac anatomy in real time. Its major advantages over existing ultrasonoscopes are its simplicity, portability, dc operation, and potentially lower production costs. Its versatility and diagnostic value were demonstrated by experienced echocardiographers.

Schmidt, G.↗
NASA NTRS1976

On the applicability of integrated circuit technology to general aviation orientation estimation

The criteria of the significant value of the panel instruments used in general aviation were examined and kinematic equations were added for comparison. An instrument survey was performed to establish the present state of the art in linear and angular accelerometers, pressure transducers, and magnetometers. A very preliminary evaluation was done of the computers available for data evaluation and estimator mechanization. The mathematical model of a light twin aircraft employed in the evaluation was documented, the results of the sensor survey and the results of the design studies were presented.

Debra, D. B.↗
NASA NTRS1977

Feasibility of a fetal measurement electrode system

Findings of the study are summarized and conclude that all monitoring requirements are not currently satisfied. An approach is presented to provide a multiparametric monitoring system through combinations of existing transducers. This monitoring system would be appropriate, not only for intrapartum monitoring, but also for neonatal and adult blood gas evaluations. A literature search was conducted to provide an insight into current state-of-the-art in fetal monitoring.

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