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  • 1
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    Obtaining a tomographic image from transmission projections (1978)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Technique for obtaining tomographic images work directly in signal space and is used to find object configuration by simple summation of density values. Image is reconstructed by precise inverse of scanning. Signal values corresponding to density of projection are added as constant terms along line corresponding to original path between two probes that give rise to that density value.
    Keywords: MATHEMATICS AND INFORMATION SCIENCES
    Type: NPO-13739 , NASA Tech Briefs (ISSN 0145-319X); 2; 4; P. 3
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Tissue identification by ultrasound (1978)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The ultrasonic properties of animal and human soft tissue were measured over the frequency range of 1.5 to 10.0 MHz. The method employed a swept-frequency, coherent technique known as time delay spectrometry. Measurements of attenuation versus frequency on liver, backfat, kidney, pancreas, spleen, breast, and other tissue were made. Considerable attention was paid to tissue handling and in determining the effects of fixing on the attenuation of ultrasound in the tissue.
    Keywords: AEROSPACE MEDICINE
    Type: NASA-CR-157776 , JPL-PUB-78-90
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Medical ultrasonic tomographic system (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An electro-mechanical scanning assembly was designed and fabricated for the purpose of generating an ultrasound tomogram. A low cost modality was demonstrated in which analog instrumentation methods formed a tomogram on photographic film. Successful tomogram reconstructions were obtained on in vitro test objects by using the attenuation of the fist path ultrasound signal as it passed through the test object. The nearly half century tomographic methods of X-ray analysis were verified as being useful for ultrasound imaging.
    Keywords: AEROSPACE MEDICINE
    Type: NASA-CR-155269 , JPL-PUB-77-72
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    A new ultrasonic imaging system using time delay spectrometry (1974)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: A new method of forming a visual image by ultrasound is described. A shadowgraphic transmission image similar to an X-ray radiograph is produced by the application of a technique known as Time Delay Spectrometry. The system uses a repetitive frequency sweep with a linear relationship between frequency and time and the transmitting and receiving crystal are scanned in raster fashion about the subject. By electronic processing, an image may be built up which represents the energy transmitted through the specimen with a given time delay. An intensity modulated picture encompassing the full shades-of-gray capability of the recording system can be produced. A second type of image showing transmission time through the specimen may also be formed. Brightness changes in the displayed image in this case correspond to changes in the ultrasonic transmission time through the specimen.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Ultrasound in Medicine and Biology; 1; 2-B,; 1974
    Format: text
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  • 5
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    Time-adjusted variable resistor (1972)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Timing mechanism was developed effecting extremely precisioned highly resistant fixed resistor. Switches shunt all or portion of resistor; effective resistance is varied over time interval by adjusting switch closure rate.
    Keywords: ELECTRONIC COMPONENTS AND CIRCUITS
    Type: NPO-11306
    Format: application/pdf
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  • 6
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    Temperature and frequency dependence of ultrasonic attenuation in selected tissues (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Ultrasonic attenuation over the frequency range of 1.5-10 MHz has been measured as a function of temperature for porcine liver, backfat, kidney and spleen as well as for a single specimen of human liver. The attenuation in these excised specimens increases nearly linearly with frequency. Over the temperature range of approximately 4-37 C the attenuation decreases with increasing temperature for most soft tissue studied.
    Keywords: LIFE SCIENCES (GENERAL)
    Type: Ultrasound in Medicine and Biology; 5; 1979
    Format: text
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  • 7
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    Method for shaping and aiming narrow beams (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A sonar method and apparatus is discribed which utilizes a linear frequency chirp in a transmitter/receiver having a correlator to synthesize a narrow beamwidth pattern from otherwise broadbeam transducers when there is relative velocity between the transmitter/receiver and the target. The chirp is so produced in a generator in bandwidth, B, and time, T, as to produce a time bandwidth product, TB, that is increased for a narrower angle. A replica of the chirp produced in a generator is time delayed and Doppler shifted for use as a reference in the receiver for correlation of received chirps from targets. This reference is Doppler shifted to select targets preferentially, thereby to not only synthesize a narrow beam but also aim the beam in azimuth and elevation.
    Keywords: COMMUNICATIONS AND RADAR
    Format: application/pdf
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  • 8
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    Pulse-width-modulated device for precision temperature control (1972)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Temperature controller is described which reduces difference between temperature oscillations about control point. Standard temperature-sensitive resistor element is utilized which is highly stable and reproducible. Temperature sensing circuitry is conventional dc bridge with power supplied by battery or highly regulated supply source.
    Keywords: ELECTRONIC SYSTEMS
    Type: NPO-11407
    Format: application/pdf
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  • 9
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    Temperature control system with a pulse width modulated bridge (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A temperature control system, which includes a modified wheatstone bridge with a resistive-capacitive (RC) circuit in one leg of the bridge, is disclosed. The RC circuit includes a resistor which provides an effective resistance as a function of its absolute resistance and the on-time to off-time ratio of pulses supplied to a switch connected across it. A sawtooth voltage is produced across the RC circuit. The voltage is compared with the voltage across a temperature sensor with heat being applied during each pulse period portion when the sawtooth voltage exceeds the voltage across the temperature sensor.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Format: application/pdf
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  • 10
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    Containerless-Processing Module (1984)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: High-temperature, containerless-processing module positions and melts molten glass or metal without contact with container wall. Fluid masses manipulated, stirred, and controlled by acoustic forces. Module provides photographic monitoring and transfer of solidified specimens to storage bins.
    Keywords: FABRICATION TECHNOLOGY
    Type: NPO-14932 , NASA Tech Briefs (ISSN 0145-319X); 8; 1; P. 142
    Format: text
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