38,048 research outputs found

    Radio Properties of the Auroral Ionosphere, Final Report (Phase I)

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    It has been found in recent years that a study of the fluctuations in the signals received from radio stars affords a powerful means of investigating the irregular structure of the ionosphere. In 1955 studies of this type, using frequencies of 223 Me and 456 Me, were initiated at the Geophysical Institute, with a view to investigating the smallscale structure of the highly disturbed auroral ionosphere. The purpose of this report is to present a complete description of the initial experimental arrangement. Further developments of the equipment and some results of analysis of the data have been presented in Quarterly Progress Reports covering the period since 1 June 1956, The report is divided into three sections. Section I contains a description of the basic philosophy of the experiment with an elementary discussion of the various parameters involved. Section II contains a brief description of the actual field installation, and Section III is devoted to the electronic design features. The diagrams pertaining to each section are located at the end of the section.Air Force Contract No. AF 30(635)-2887 Project No. 5535 - Task 45774 Rome Air Development Center, Griffiss Air Force Base Rome, New YorkABSTRACT AND GENERAL INTRODUCTION -- [SECTION I] Investigation of the Ionosphere Using Extra- Terrestrial Radio Sources : 1.1 Introduction ; 1.2 Extra-Terrestrial Sources ; Apparent Positions ; 1.3 Instrumental Techniques for the Study of Radiation from Radio Stars ; Interferometer Methods ; Advantages of the Phase-Switch Interferometer ; Interferometer Parameters ; 1.5 Limitations on Accuracy -- References -- [SECTION II] The Field Installation : 2.1 Introduction ; 2.2 The Radio Telescope Towers ; 2.3 The Antennas ; 2.4 Acknowledgements -- [SECTION III] Electronic Design of Phase-Switch Interferometers : 3.1 Introduction ; 3.2 223 Mc Phase-Switch Equipment ; 3.3 456 Mc Phase-Switch Equipment ; 3.4 Auxiliary EquipmentYe

    Carbon deposition in the Bosch process with ruthenium and ruthenium-iron alloy catalysts

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    The effectiveness of ruthenium and the alloys 50Ru50Fe and 33Ru67Fe as alternatives to iron, nickel, and cobalt catalysts in recovering oxygen from metabolic carbon dioxide was investigated. Carbon deposition boundaries over the unsupported alloys are reported. Experiments were also carried out over 50Ru50Fe and 97Ru3Fe3 catalysts supported on gamma-alumina to determine their performance in the synthesis of low molecular weight olefins. High production of ethylene and propylene would be beneficial for an improvement of an overall Bosch process, as a gas phase containing high olefin content would enhance carbon deposition in a Bosch reactor

    A multifrequency evaluation of active and passive microwave sensors for oil spill detection and assessment

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    An evaluation is given of how active and passive microwave sensors can best be used in oil spill detection and assessment. Radar backscatter curves taken over oil spills are presented and their effect on synthetic aperture radar (SAR) imagery are discussed. Plots of microwave radiometric brightness variations over oil spills are presented and discussed. Recommendations as to how to select the best combination of frequency, viewing angle, and sensor type for evaluation of various aspects of oil spills are also discussed

    New broadband square-law detector

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    Compact device has wide dynamic range, accurate square-law response, good thermal stability, high-level dc output with immunity to ground-loop problems, ability to insert known time constants for radiometric applications, and fast response times compatible with computer systems

    Acoustic signatures of the seafloor: Tools for predicting grouper habitat

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    Groupers are important components of commercial and recreational fisheries. Current methods of diver-based grouper census surveys could potentially benefit from development of remotely sensed methods of seabed classification. The goal of the present study was to determine if areas of high grouper abundance have characteristic acoustic signatures. A commercial acoustic seabed mapping system, QTC View Series V, was used to survey an area near Carysfort Reef, Florida Keys. Acoustic data were clustered using QTC IMPACT software, resulting in three main acoustic classes covering 94% of the area surveyed. Diver-based data indicate that one of the acoustic classes corresponded to hard substrate and the other two represented sediment. A new measurement of seabed heterogeneity, designated acoustic variability, was also computed from the acoustic survey data in order to more fully characterize the acoustic response (i.e., the signature) of the seafloor. When compared with diver-based grouper census data, both acoustic classification and acoustic variability were significantly different at sites with and without groupers. Sites with groupers were characterized by hard bottom substrate and high acoustic variability. Thus, the acoustic signature of a site, as measured by acoustic classification or acoustic variability, is a potentially useful tool for stratifying diver sampling effort for grouper census

    Gauge Symmetry, T-Duality and Doubled Geometry

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    String compactifications with T-duality twists are revisited and the gauge algebra of the dimensionally reduced theories calculated. These reductions can be viewed as string theory on T-fold backgrounds, and can be formulated in a `doubled space' in which each circle is supplemented by a T-dual circle to construct a geometry which is a doubled torus bundle over a circle. We discuss a conjectured extension to include T-duality on the base circle, and propose the introduction of a dual base coordinate, to give a doubled space which is locally the group manifold of the gauge group. Special cases include those in which the doubled group is a Drinfel'd double. This gives a framework to discuss backgrounds that are not even locally geometric.Comment: 16 page

    A Parametric Study of Tillage Effects on Radar Backscatter

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    Radar backscatter data for different field configurations and modulation function curves for angular and frequency variations are presented. A simplistic approach to modeling this effect is presented. It is concluded that: (1) row direction is a significant contributor to radar backscatter from cropland and must be considered when making radar measurements over bare or sparsely vegetated fields; (2) while the effect decrease with increasing frequency, it is still large (5 dB) at 13.3 GHz; (3) row effects are independent of linear polarization; (4) there is a strong aspect angle sensitivity which is a function of the scene and radar system parameters

    Oxygen complexes formed at 4 K

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    Storage stability of oxygen complexes at 4

    Radiation Information from 1958 δ2

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    The telemetered radiation information from the satellite 1958 δ2 (Sputnik III) has been analyzed for sixty-two separate passes recorded in College, Alaska. The data indicate a dependence of radiation intensity on altitude in the range 250-500 km. Both the high and low energy components apparently contribute to the overall increase of intensity with altitude, but the presence of a continuous afterglow in the scintillating crystal prevented detailed interpretation of the results.IGY Project No. 32.42 NSF Grant No. Y/32.42/268Ye
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