Author: Edmund B. Weis (Jr.)
Publisher:
ISBN:
Category : Anoxemia
Languages : en
Pages : 15

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Author: J. J. Wortman
Publisher:
ISBN:
Category : Oxygen
Languages : en
Pages : 100

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The development is described of a laboratory model oxygen partial pressure sensor using a sputtered zinc oxide thin film. The film is operated at about 400 C through the use of a miniature silicon bar. Because of the unique resistance versus temperature relation of the silicon bar, control of the operational temperature is achieved by controlling the resistance. A circuit for accomplishing this is described. The response of sputtered zinc oxide films of various thicknesses to oxygen, nitrogen, argon, carbon dioxide, and water vapor caused a change in the film resistance. Over a large range, film conductance varied approximately as the square root of the oxygen partial pressure. The presence of water vapor in the gas stream caused a shift in the film conductance at a given oxygen partial pressure. A theoretical model is presented to explain the characteristic features of the zinc oxide response to oxygen.

Author: Gerald Jankowitz
Publisher:
ISBN:
Category : Air sampling apparatus
Languages : en
Pages : 48

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The objective of the program was to design and develop a compact airborne CO2 sensor unit capable of sensing and measuring the CO2 content of manned, sealed environments. A prototype carbon dioxide sensor was designed, built, and calibrated. The sensor operates by alternately comparing the infrared absorption of the air sample at 4.26 microns, where CO2 exhibits strong absorption and at 3.90 microns where it has little absorption. A two color rotating filter provides sampling 200 times per second. The unit weighs 10 pounds and has a power consumption of 70 watts. The instrument is capable of detecting a concentration of at least 0.30% CO2 and has full scale capability to 5%. (Author).

Author: Mohieddine Benammar
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Electronic instrumentation was developed for the measurement of the oxygen partial pressure, P1 (in a sample gas using fully-sealed zirconia pump-gauge oxygen sensors operated in an AC mode. These sensors, operated typically at 700?C, consisted of two discs of zirconia with porous platinum electrodes on each face separated by a gold seal and enclosing a small internal volume. One disc was operated as a pump enabling oxygen to be electrochemically transferred into and out of the enclosed volume; the other disc operated as a gauge, the Nernst EMF across the electrodes providing a measure of the ratio of the internal to the external oxygen partial pressure. By careful design of the circuitry it was possible to measure the oxygen partial pressure, P, without the need for a separate reference gas supply. Subsequently, a novel "tracking" mode of operation was proposed and implemented in which leakage effects generally associated with sealed pump-gauge devices were minimised: the sensor was operated in a feedback control-loop in order to adjust automatically the mean internal reference oxygen partial pressure, P0, so as to maintain the ratio (Px/P0) close to unity. The signal-to-noise ratio was markedly improved by using gauge EMFs with high amplitudes which inevitably display a distorted sinusoid due to the logarithmic term in the Nernst equation. Surprisingly, mathematical analysis predicted that the linearity of the output of the instrument using phase-sensitive detection should not be affected by the deviation from a sinusoid and this was confirmed experimentally: signal processing was practically implemented using simple analogue electronics. As anticipated there was a strong influence of sensor temperature on the output of the instrument: consequently, methods for temperature compensation were proposed and shown to be feasible with minimum hardware. The theory of Operation of leaky pump-gauge was also developed which indicated that a physical leak in the sensor should cause a phase shift and amplitude change in the sensor output. Experimental results were, in general, in agreement with the theory demonstrating the influences of the geometry and dimensions of the leak and of the operating frequency. Importantly, the theory predicted that, when operated in the AC mode, devices with major leakage may still be used for oxygen partial pressure measurement: again this was confirmed by experiment and the additional benefit of a concomitant substantial simplification of the electronic circuitry also realised. Interestingly an unexpected but small influence of oxygen concentration on the phase shift was observed: this requires additional study.

Author: Carl Raymond Pearson
Publisher:
ISBN:
Category : Oxygen
Languages : en
Pages : 88

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Author: Richard W. Alnutt
Publisher:
ISBN:
Category : Detectors
Languages : en
Pages : 82

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Book Description
This third, and final, volume is devoted to a discussion of monitoring systems. While the applications of physiological monitoring are many and varied, the primary concern here is with viability monitoring, the use of a measurement system to obtain factual, quantitative information about the physiological responses of a subject in a stressful environment, in order to plan protective measures which will ensure the safety and functional capability of that subject in such environments. Included are a description of instrumentation required for the measurement of individual physiological parameters, a discussion of related problems in system design, including simultaneous measurement of several parameters, data transmission or telemetry, and the use of magnetic tape recording as a system adjunct. Basic guidelines of system troubleshooting and interference reduction are also included. Section IV contains a brief survey of additional measurement techniques and data handling considerations which, while not state of the art or standard practice, will undoubtedly affect the field of physiological monitoring in the near future.

Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 1572

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Author: United States. National Aeronautics and Space Administration Scientific and Technical Information Division
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 478

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Author: United States. Wright Air Development Division
Publisher:
ISBN:
Category :
Languages : en
Pages : 28

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 216

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Book Description