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  • INSTRUMENTATION AND PHOTOGRAPHY  (533)
  • 1990-1994  (264)
  • 1975-1979  (269)
  • 1945-1949
  • 1
    Publication Date: 2013-08-31
    Description: Total ozone data obtained during summers at Mauna Loa Observatory, Hawaii, with Dobson Spectrophotometer 83 are routinely compared with overpass total ozone data from the Total Ozone Mapping Spectrometer (TOMS) and the Solar Backscatter Ultraviolet (SBUV) spectrometer launched aboard the Nimbus 7 satellite in 1978. Results from the TOMS/Dobson instrument comparisons through 1990 have been presented by McPeters and Komhyr (1991). Dobson spectrophotometer 83 was established as the standard instrument for the U.S.A. Dobson instrument station network in 1962. In 1980, the instrument was designated by the World Meteorological Organization (WMO) as the Standard Dobson Spectrophotometer for the World. Long-term ozone measurement precision of the instrument has been maintained at plus or minus 0.5 percent (Komhyr et al., 1989). On an absolute scale, the ozone measurement accuracy of the instrument is estimated to plus or minus 3 percent. In early April, 1990, comparison of total ozone and vertical distribution (Umkehr) observations were made for the first time with Dobson spectrophotometer 8.3. The work was conducted at the NOAA Climate Monitoring and Diagnostics Laboratory (CMDL) in Boulder, Colorado, and at the research and instrument manufacturing facility of the Ball Aerospace System Division located about 2 km east of Boulder. (The SBUV-2 S/N-2 instrument, built by Ball Aerospace Systems Division, is scheduled for launch aboard the NOAA-13 satellite). We present results of the comparisons which include ozone vertical distribution data obtained with a balloon-borne electrochemical concentration cell (ECC) ozonesonde (Komhyr, 1969).
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center, Ozone in the Troposphere and Stratosphere, Part 2; p 962-965
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  • 2
    Publication Date: 2013-08-31
    Description: The Dobson ozone spectrophotometer measures the difference of intensity between selected wavelengths in the ultraviolet. The method uses an optical attenuator (the 'Wedge') in this measurement. The knowledge of the relationship of the wedge position to the attenuation is critical to the correct calculation of ozone from the measurement. The procedure to determine this relationship is time-consuming, and requires a highly skilled person to perform it correctly. The relationship has been found to change with time. For reliable ozone values, the procedure should be done on a Dobson instrument at regular intervals. Due to the skill and time necessary to perform this procedure, many instruments have gone as long as 15 years between procedures. This article describes an apparatus that performs the procedure under computer control, and is adaptable to the majority of existing Dobson instruments. Part of the apparatus is usable for normal operation of the Dobson instrument, and would allow computer collection of the data and real-time ozone measurements.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center, Ozone in the Troposphere and Stratosphere, Part 2; p 749-753
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  • 3
    Publication Date: 2011-08-17
    Description: Described in detail is a laser induced fluorescence system which has been successfully interfaced with two aircraft sampling platforms (i.e., Sabreliner jet and an L-188C Electra). This system, which has been under development for four years, presently consists of the following major components: (1) a Nd-Yag laser driven oscillator-amplifier dye laser; (2) a sampling manifold with associated fluorescence detection optics; (3) an OH calibration chamber; (4) a laser beam steering assembly; and (5) sampling electronics and data processing hardware. During the last three years, this system has been flown some 50,000 air miles making tropospheric OH radical measurements over the latitude range of 70 N to 57 S. OH concentrations measured during these flights have ranged from 30 parts-per-quadrillion (3.7 x 10 to the 5th molecules/sq cm) at altitudes of 6 km to 0.8 parts-per-trillion (2.0 x 10 to the 7th molecules/sq cm) at 0.5 km. Computations have been completed which indicate that the existing aircraft system with modest modifications should also be capable of detecting natural tropospheric levels of NO, SO2, CH2O, NO2, HNO2, NO3, H2O2 and CS2 by using both conventional laser-induced fluorescence methodology and multiphoton techniques.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 50; Dec. 197
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  • 4
    Publication Date: 2019-06-28
    Description: This paper focuses on the design, construction, preliminary testing, and potential applications of three forms of miniaturized analytical instrumentation. The first is an optical fiber instrument for monitoring pH and other cations in aqueous solutions. The instrument couples chemically selective indicators that were immobilized at porous polymeric films with a hardware package that provides the excitation light source, required optical components, and detection and data processing hardware. The second is a new form of a piezoelectric mass sensor. The sensor was fabricated by the deposition of a thin (5.5 micron) film of piezoelectric aluminum nitride (AIN). The completed deposition process yields a thin film resonator (TFR) that is shaped as a 400 micron square and supports a standing bulk acoustic wave in a longitudinal mode at frequencies of approx. 1 GHz. Various deposition and vapor sorption studies indicate that the mass sensitivity of the TFR's rival those of the most sensitive mass sensors currently available, though offering such performance in a markedly smaller device. The third couples a novel form of liquid chromatography with microlithographic miniaturization techniques. The status of the miniaturization effort, the goal of which is to achieve chip-scale separations, is briefly discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-CR-191988 , NAS 1.26:191988
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  • 5
    Publication Date: 2019-06-27
    Description: Measurements obtained with laser velocimetry in a Mach 2.9 separated turbulent boundary layer and in the transonic flow past a two-dimensional airfoil section are presented and compared to data realized by conventional techniques. Agreement in mean velocities was realized where the pressure measurements could be considered reliable; however, in regions of instantaneous reverse velocities, the laser results were found to be consistent with the physics of the flow whereas the pressure data were not. Streamwise turbulence intensities are also presented. In the transonic airfoil study, velocity measurements obtained immediately outside the upper surface boundary layer of a 6-inch chord NACA 64A010 airfoil are compared to edge velocities inferred from surface pressure measurements. For free-stream Mach numbers of 0.6 and 0.8, the agreement in results was very good. "Dual scatter" optical arrangements in conjunction with a single particle, counter-type signal processor were employed in these investigations.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-TM-X-73117 , A-6510
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  • 6
    Publication Date: 2019-06-27
    Description: The response of a tungsten-scintillator ionization spectrometer to accelerated particle beams has been investigated. Results obtained from exposure of the approx. 1000 g/sq cm apparatus to 5, 10, and 15 GeV/c electrons and pions as well as to 2.1 GeV/nucleon C-12 and O-16 ions are presented. These results include cascade-development curves, fractions of the primary energy measured by the spectrometer, and resolutions of the apparatus for measuring the primary energies. For 15 GeV/c electrons, an average of about 82% of the incident energy is measured by the apparatus with resolution (normal standard deviation) of about 6%. For 15 GeV/c pions, an average of about 65% of the incident energy is measured with resolution of about 18%. The energy resolution improves with increasing energy and with increasing depth of the spectrometer.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Nuclear Instruments and Methods; 126; 1975
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  • 7
    Publication Date: 2019-06-27
    Description: A simple technique for single-scan T1 measurements in solids is proposed and analyzed for single exponential spin-lattice relaxation. In this technique, the direct spin heating caused by the sampling process is significantly reduced in comparison with conventional techniques by utilizing the 'solid echo' to refocus the magnetization. The applicability of this technique to both the solid and liquid phases is demonstrated.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 49; Aug. 197
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  • 8
    Publication Date: 2019-06-27
    Description: The problems of developing large-area, gas-scintillation proportional counters with high resolution are considered. It is found that simple large-area, parallel-grid proportional counters suffer from a variation in gain over the counter window. Some success has been achieved in overcoming this problem by focusing the charge cloud as it drifts into the multiplication region. Measurements are reported for various mixtures of argon and xenon as well as pure xenon.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 9
    Publication Date: 2019-07-12
    Description: The application of CCDs to X-ray imaging and spectroscopy in astronomy is discussed with special attention given to the special requirements of CCDs for X-ray astronomy (as opposed to those for traditional optical applications). The development status of CCDs for X-ray astronomy applications is described, and results of recent research in the area of optimizing the CCD X-ray response are presented. It is shown that very high quantum efficiencies and Fano noise-limited energy resolutions can be obtained using CCDs.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Experimental Astronomy (ISSN 0922-6435); 2; 3 19
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  • 10
    Publication Date: 2019-08-28
    Description: This paper focuses on the design, construction, preliminary testing, and potential applications of three forms of miniaturized analytical instrumentation. The first is an optical fiber instrument for monitoring pH and other cations in aqueous solutions. The instrument couples chemically selective indicators that were immobilized at porous polymeric films with a hardware package that provides the excitation light source, required optical components, and detection and data processing hardware. The second is a new form of a piezoelectric mass sensor. The sensor was fabricated by the deposition of a thin (5.5 micron) film of piezoelectric aluminum nitride (AIN). The completed deposition process yields a thin film resonator (TFR) that is shaped as a 400 micron square and supports a standing bulk acoustic wave in a longitudinal mode at frequencies of approx. 1 GHz. Various deposition and vapor sorption studies indicate that the mass sensitivity of the TFR's rival those of the most sensitive mass sensors currently available, though offering such performance in a markedly smaller device. The third couples a novel form of liquid chromatography with microlithographic miniaturization techniques. The status of the miniaturization effort, the goal of which is to achieve chip-scale separations, is briefly discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: SAE PAPER 921179 , ; 11 p.|SAE, International Conference on Environmental Systems; Jul 13, 1992 - Jul 16, 1992; Seattle, WA; United States
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