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  • 1
    Electronic Resource
    Electronic Resource
    In vitro velocity measurements in the near vicinity of the Bjork-Shiley aortic prosthesis using a laser-Doppler anemometer (1979)
    Springer
    Medical & biological engineering & computing 17 (1979), S. 453-459 
    Details
    ISSN: 1741-0444
    Keywords: Björk-Shiley aortic valve ; in vitro velocity measurements ; Laser-Doppler anemometer Shear stress measurements ; Thrombus formation ; Tissue overgrowth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract In this study,in vitro velocity measurements in the near vicinity of a Björk-Shiley aortic valve, one of the more commonly used aortic valve prostheses, were made using a laser-Doppler anemometer. The velocity measurements identified a zone of stagnation, about 20 mm wide, immediately downstream from the fully open disc. The measurements also showed that the flow through the valve was divided into two unequal regions, namely, the major and minor outflow regions. Because of the low flow in the minor outflow region, the shear stresses along the perimeter of the valve in that region were considerably lower than the shear stresses along the sewing ring of the major outflow region. Pathologic studies of nine recovered Björk-Shiley aortic valves indicated varying amounts of thrombus formation on the outflow face of the disc and excess growth of endothelial tissue along the perimeter of the minor outflow region. If the large stagnation zone and the relatively low shear in the minor outflow region which were observed in thein vitro measurements also existin vivo, they could lead to the clinically observed thrombus formation and tissue overgrowth, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02447057
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    Paper (German National Licenses)
    Fulltext
  • 2
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    Electromagnetic Probe Technique for Fluid Flow Measurements (1994)
    In:  CASI
    Details
    Publication Date: 2009-11-16
    Description: The probes described herein, in various configurations, permit the measurement of the volume fraction of two or more fluids flowing through a pipe. Each probe measures the instantaneous relative dielectric constant of the fluid in immediate proximity. As long as separation of the relative dielectric constants of each fluid is possible, several or even many fluids can be measured in the same flow steam. By using multiple probes, the velocity of each fluid can generally be determined as well as the distribution of each constituent in the pipe. The values are determined by statistical computation. There are many potential applications for probes of this type in industry and government. Possible NASA applications include measurements of helium/hydrazine flow during rocket tests at White Sands, liquid/gas flow in hydrogen or oxygen lines in Orbiter engines, and liquid/gaseous Freon flow in zero gravity tests with the KS135 aircraft at JSC. Much interest has been shown recently by the oil industry. In this industry, a good method is needed to measure the fractions of oil, water, and natural gas flowing in a pipeline and the velocity of each. This particular problem involves an extension of what has been developed to date and our plans and program to solve this problem will be discussed herein.
    Keywords: Fluid Mechanics and Heat Transfer
    Type: Dual-Use Space Technology Transfer Conference and Exhibition; Volume 1; 15-22; NASA-CP-3263-Vol-1
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    Determination of the Residence Time of Food Particles During Aseptic Sterilization (1994)
    In:  CASI
    Details
    Publication Date: 2009-11-16
    Description: The paper describes a non-invasive method to measure the time an individual particle takes to move through a length of stainless steel pipe. The food product is in two phase flow (liquids and solids) and passes through a pipe with pressures of approximately 60 psig and temperatures of 270-285 F. The proposed problem solution is based on the detection of transitory amplitude and/or phase changes in a microwave transmission path caused by the passage of the particles of interest. The particles are enhanced in some way, as will be discussed later, such that they will provide transitory changes that are distinctive enough not to be mistaken for normal variations in the received signal (caused by the non-homogeneous nature of the medium). Two detectors (transmission paths across the pipe) will be required and place at a known separation. A minimum transit time calculation is made from which the maximum velocity can be determined. This provides the minimum residence time. Also average velocity and statistical variations can be computed so that the amount of 'over-cooking' can be determined.
    Keywords: Life Sciences (General)
    Type: Dual-Use Space Technology Transfer Conference and Exhibition; Volume 1; 7-14; NASA-CP-3263-Vol-1
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    Electromagnetic probe technique for fluid flow measurements (1994)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The probes described herein, in various configurations, permit the measurement of the volume fraction of two or more fluids flowing through a pipe. Each probe measures the instantaneous relative dielectric constant of the fluid in immediate proximity. As long as separation of the relative dielectric constant of the fluid is possible, several or even many fluids can be measured in the same flow stream. By using multiple probes, the velocity of each fluid can generally be determined as well as the distribution of each constituent in the pipe. The values are determined by statistical computation. There are many potential applications for probes of this type in industry and government. Possible NASA applications include measurements of helium/hydrazine flow during rocket tests at White Sands, liquid/gas flow in hydrogen or oxygen lines in Orbiter engines, and liquid/gaseous Freon flow in zero gravity tests with the KS135 aircraft at JSC. Much interest has been shown recently by the oil industry. In this a good method is needed to measure the fractions of oil, water, and natural gas flowing in a pipeline and the velocity of each. This particular problem involves an extension of what has been developed to date and our plans to solve this problem will be discussed herein.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA, Washington, Technology 2003: The Fourth National Technology Transfer Conference and Exposition, Volume 2; p 301-310
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 5
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    Gemini rendezvous radar error. (1966)
    In:  Other Sources
    Details
    Publication Date: 2019-05-30
    Description: Errors in Gemini rendezvous radar interferometer due to antenna ellipticity and coupling of adjacent antennas
    Keywords: COMMUNICATIONS
    Type: MICROWAVE JOURNAL
    Format: text
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  • 6
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    Microwave-Spectral Signatures Would Reveal Concealed Objects (2004)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: A proposed technique for locating concealed objects (especially small antipersonnel land mines) involves the acquisition and processing of spectral signatures over broad microwave frequency bands. This technique was conceived to overcome the weaknesses of older narrow- band electromagnetic techniques like ground-probing radar and low-frequency electromagnetic induction. Ground-probing radar is susceptible to false detections and/or interference caused by rocks, roots, air pockets, soil inhomogeneities, ice, liquid water, and miscellaneous buried objects other than those sought. Moreover, if the radar frequency happens to be one for which the permittivity of a sought object matches the permittivity of the surrounding soil or there is an unfavorable complex-amplitude addition of the radar reflection at the receiver, then the object is not detected. Low-frequency electromagnetic induction works well for detecting metallic objects, but the amounts of metal in plastic mines are often too small to be detectable. The potential advantage of the proposed technique arises from the fact that wideband spectral signatures generally contain more relevant information than do narrow-band signals. Consequently, spectral signatures could be used to make better decisions regarding whether concealed objects are present and whether they are the ones sought. In some cases, spectral signatures could provide information on the depths, sizes, shapes, and compositions of objects. An apparatus to implement the proposed technique (see Figure 1) could be assembled from equipment already in common use. Typically, such an apparatus would include a radio-frequency (RF) transmitter/receiver, a broad-band microwave antenna, and a fast personal computer loaded with appropriate software. In operation, the counter would be turned on, the antenna would be aimed at the ground or other mass suspected to contain a mine or other sought object, and the operating frequency would be swept over the band of interest.
    Keywords: Man/System Technology and Life Support
    Type: MSC-22839 , NASA Tech Briefs, September 2004; 23-24
    Format: application/pdf
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  • 7
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    Microwave/Sonic Apparatus Measures Flow and Density in Pipe (2004)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: An apparatus for measuring the rate of flow and the mass density of a liquid or slurry includes a special section of pipe instrumented with microwave and sonic sensors, and a computer that processes digitized readings taken by the sensors. The apparatus was conceived specifically for monitoring a flow of oil-well-drilling mud, but the basic principles of its design and operation are also applicable to monitoring flows of other liquids and slurries.
    Keywords: Instrumentation and Photography
    Type: MSC-23311 , NASA Tech Briefs, June 2004; 7-8
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 8
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    Microwave Treatment of Prostate Cancer and Hyperplasia (2005)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: Microwave ablation in the form of microwave energy applied to a heart muscle by a coaxial catheter inserted in a vein in the groin area can be used to heat and kill diseased heart cells. A microwave catheter has been developed to provide deep myocardial ablation to treat ventricular tachycardia by restoring appropriate electrical activity within the heart and eliminating irregular heartbeats. The resulting microwave catheter design, which is now being developed for commercial use in treating ventricular tachycardia, can be modified to treat prostate cancer and benign prostatic hyperplasia (BPH). Inasmuch as the occurrence of BPH is increasing currently 350,000 operations per year are performed in the United States alone to treat this condition this microwave catheter has significant commercial potential.
    Keywords: Man/System Technology and Life Support
    Type: MSC-23049 , NASA Tech Briefs, June 2005; 25
    Format: application/pdf
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  • 9
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    Medium-Frequency Pseudonoise Georadar (2005)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: Ground-probing radar systems featuring medium-frequency carrier signals phase-modulated by binary pseudonoise codes have been proposed. These systems would be used to locate and detect movements of subterranean surfaces; the primary intended application is in warning of the movement of underground water toward oil-well intake ports in time to shut down those ports to avoid pumping of water. Other potential applications include oil-well logging and monitoring of underground reservoirs. A typical prior georadar system operates at a carrier frequency of at least 50 MHz in order to provide useable range resolution. This frequency is too high for adequate penetration of many underground layers of interest. On the other hand, if the carrier frequency were to be reduced greatly to increase penetration, then bandwidth and thus range resolution would also have to be reduced, thereby rendering the system less useful. The proposed medium-frequency pseudonoise georadar systems would offer the advantage of greater penetration at lower carrier frequencies, but without the loss of resolution that would be incurred by operating typical prior georadar systems at lower frequencies.
    Keywords: Earth Resources and Remote Sensing
    Type: MSC-23029 , NASA Tech Briefs, September 2005; 12-13
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 10
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    Fluid flow volume measurements using a capacitance/conductance probe system (1995)
    In:  Other Sources
    Details
    Publication Date: 2019-07-17
    Description: A probe system has been developed to measure the flow volume of a single fluid passing through an orifice or flow line. The system employs both capacitance and a conductance probe at the orifice, together with phase detection and data acquisition circuitry to measure flow volume and salinity under low or zero gravity conditions. A wide variety of frequencies can be used for the radio frequency (RF) signal source which is chosen primarily by the capacitance of the orifice probe and the fluid passing through the orifice. Rapid measurements are made using the reflected signal from the orifice probe to determine the 'instantaneous' permittivity of the fluid/gas mixture passing through. The 'instantaneous' measurements are integrated over time to determine flow volume. Analysis reveals that a narrow orifice helps to reduce non-linearities caused by differing flow rates. The geometry of 'deflectors' and 'directors' for the flowing fluid are important in obtaining linearity. Measured data shows that a volume measurement accuracy of approximately four percent can be consistently achieved. The prototype hardware system and associated software have been optimized and are available for further applications. The system has immediate application in low or zero gravity environments for measurements of urine or other liquid volumes.
    Keywords: Fluid Mechanics and Heat Transfer
    Type: Proceedings of the International Conference on Integrated Micro/Nanotechnology for Space Applications; NASA-CR-201963
    Format: text
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    NASA TECHNICAL REPORTS
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