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  • Other Sources  (7,098)
  • NASA Technical Reports  (7,098)
  • Articles (OceanRep)
  • ASTROPHYSICS  (2,970)
  • METEOROLOGY AND CLIMATOLOGY  (1,775)
  • INSTRUMENTATION AND PHOTOGRAPHY  (1,282)
  • COMMUNICATIONS AND RADAR  (1,071)
  • 1980-1984  (7,093)
  • 1955-1959  (5)
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  • Other Sources  (7,098)
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  • NASA Technical Reports  (7,098)
  • Articles (OceanRep)
Keywords
Years
Year
  • 1
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    Radar backscatter modelling (1984)
    In:  CASI
    Details
    Publication Date: 2006-04-06
    Description: The terrain analysis software package was restructured and documentation was added. A program was written to test Johnson Space Center's four band scatterometer data for spurious signals data. A catalog of terrain roughness statistics and calibrated four frequency multipolarization scatterometer data is being published to support the maintenance of Death Valley as a radar backscatter calibration test site for all future airborne and spacecraft missions. Test pits were dug through sand covered terrains in the Eastern Sahara to define the depth and character of subsurface interfaces responsible for either backscatter or specular response in SIR-A imagery. Blocky sandstone bedrock surfaces at about 1 m depth were responsible for the brightest SIR-A returns. Irregular very dense CaCO3 cemented sand interfaces were responsible for intermediate grey tones. Ancient river valleys had the weakest response. Reexamination of SEASAT l-band imagery of U.S. deserts continues.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA. Washington Rept. of Planetary Geology Program, 1983; p 268-269
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  • 2
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    Design optimization of the 34-meter DSN-NCP antennas (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The new NASA Deep Space Network (DSN) 34-m-diameter azimuth-elevation (Az-El) antenna structure is an example of an essentially computer-automated design. In addition to pivotal comptuer Lagrange multiplier design optimization software, much of the associated pre- and post-processing was also performed by computer. The construction of one of these antennas at Goldstone, California, is well advanced and will be completed this summer. A second installation is in progress in Australia. Both atennas will be used primarily for spacecraft tracking and will operate in the 8.5-GHz, 3.5-cm (1.4-in.) wavelength microwave frequency.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 2; 16 p
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  • 3
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    Distortion measurement of antennas under space simulation conditions with high accuracy and high resolution by means of holography (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The use of laser holography for measuring the distortion of antennas under space simulation conditions is described. The subject is the so-called double exposure procedure which allows to measure the distortion in the order of 1 to 30/micrometers + or - 0.5 per hologramme of an area of 4 m diameter max. The method of holography takes into account the constraints of the space simulation facility. The test method, the test set up and the constraints by the space simulation facility are described. The results of the performed tests are presented and compared with the theoretical predictions. The test on the K-Band Antenna e.g., showed a distortion of approximately 140/micrometers + or - 5/micrometers measured during the cool down from -10 C to -120 C.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center 13th Space Simulation Conf.; p 309-319
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  • 4
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    Speech communications in noise (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The physical characteristics of speech, the methods of speech masking measurement, and the effects of noise on speech communication are investigated. Topics include the speech signal and intelligibility, the effects of noise on intelligibility, the articulation index, and various devices for evaluating speech systems.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Physiol., Psychol., and Social Effects of Noise; p 57-110
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  • 5
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    RIMSTAR: Rapid image scanning technology and archiving (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Conventional schemes for digitizing large volumes of photographic data are far too costly and time consuming to encourage the undertaking of the ambitious projects using traditional technology. There is a distinct need for fast digitizing systems such as could be derived from development of large format, optically multiplexed CCD systems designed to address these problems. The use of CCD chips for data handling and the capability of using polaroids in the optical path for reduced light scattering are discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 419-427
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  • 6
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    Photographic surveys of the southern sky (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Parameters of the UK 1.2 meter Schmidt telescope are described. Plates taken with this instrument are in two categories, those for systematic sky surveys and those taken at the request of research users. A collaborative project with the European Southern Observatory was undertaken to obtain a two-color survey of the sky south of -20 deg declination to complement the Palomar survey. A near infrared survey of the Galactic Plane and the Megallanic Clouds is being done. The area south of -20 deg and the zone between 0 deg and -15 deg are also being surveyed. Pending a decision on survey parameters, all available A quality prism plates are being retained to form a basis for systematic survey. Nearly half the plates taken on a service basis for the UK astronomical community are to fulfill nonsurvey requests. Plates taken for surveys which are not of A grade quality are also made available for research purposes.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 379-385
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  • 7
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    The preparation of the measurements at the PDS at the Padova Observatory: Report on an experience with the development of an astronomical data base environment (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Some software facilities used mainly for information retrieval and analysis at the Padova-Asiago Observatory are discussed. These facilities help guest and resident astronomers to make easier the preparation of plate measurements. The problems connected with the creation, use and management of a data base in a scientific (astronomical) environment are reviewed on the basis of the experience gathered during the last three years. The development plan of the user session environment and its possible applications in a computer network are briefly sketched.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 361-369
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  • 8
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    Plans for a fast image recording system at ESO (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A 256 diode-array will be installed as detector on the ESO OPTRONICS S-3000 measuring machine in order to increase the acquisition rate. A high intensity LED will be used as light source in a pulse mode. The data will be stored on a random access mass storage device as density values for later education. The scanning time for a 30 cm x 30 cm plate with a step size of 10 micron will be less than 10 hours while the dynamic range of the data is expected to be 2.5 density units with an offset of at least 1 unit.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 317-328
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  • 9
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    The automated photographic measuring facility at Cambridge (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The design and performance of the automated photographic measuring facility at Cambridge is described. It consists of a precision laser scanning microdensitometer connected to a series of computers that process the data on-line. Plates up to 350 mm square can be measured. The microdensitometer samples the plate to 12 bit accuracy at a speed of 230,000 samples/second. The positional accuracy is better than a micron. Other features include platen rotation and automatic focus.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 277-288
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  • 10
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    Techniques of isophotometry (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The expected performance of the Minnesota automated dual-plate scanner (APS) is discussed with regard to photometry, position measurement accuracy, and ability to classify images. In addition, a fast algorithm for calculating image parameters is described.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 267-276
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  • 11
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    The current status and future upgrade of the PDS at the Royal Greenwich Observatory (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Various aspects of the performance of the PDS 1010A microdensitometer are described. The primary points in an upgrade propsal for the unit are outlined. Photometric instabilities in the PDS are mentioned.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 129-134
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  • 12
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    Microdensitometer electronics modification (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Minor modifications of electronic components in the PDS 1010A microdensitometer are discussed. The operational requirements and performance limitations of the PDS are noted. Replacement of the photomultiplier and front-end analog circuitry significantly improved the photometric performance of the PDS. The improvement in density repeatability is marked, and the permissible density slew speed is greatly increased.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 121-128
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  • 13
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    Performance testing of the high altitude observatory PDS microdensitometer (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: High Altitude Observatory HAO microdensitometer undergoes monthly testing to assure its consistent performance. These tests check positional and photometric stability at the 10 micron aperture level. The HAO test procedure is designed to run without operator intervention following initial configuration of the microdensitometer for each subprocedure. Specialized test software is resident in the PDP 8. The operator selects the proper subprocedure by entering commands. Once computer control is established, it is not relinquished until the test is complete.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Astron. Microdensitometry Conf.; p 19-34
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  • 14
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    Diagnosing a PDS microdensitometer (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A number of diagnostic tests are developed for the Photometric Data System PDS 2020G microdensitometer to monitor its performance and to isolate various electromechanical problems. A number of tests which help to diagnose problems with the photometer, positional accuracy and data collection are described. The tests include: (1) scanning a razor blade edge to study the response of the photometer and zero point losses in the coordinate system, (2) scanning a long straight line to evaluate the drunkness of the stage motions, (3) scanning photometric step wedge calibrations to study the response of the photometer, and (4) measurement of a series of high signal to noise plates of the same region of the sky to evaluate the overall performance of the microdensitometer. A variety of electronic tests to isolate electromechanical problems are also performed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 3-18
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  • 15
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    Ruled and holographic gratings experiment (A0138-5) (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The behavior of ruled and holographic gratings with various coatings after extended exposure to the space environments was examined. The coatings and differentiating between the influences of vacuum and solar illumination were examined. In the past, several ruled and holographic gratings with various coatings were successfully flown on rocket experiments. Future utilizations of such gratings are considered for the Space Telescope and for various Spacelab projects under development. The techniques which is used to replicate gratings can also be used to obtain a wide range of lightweight optical components, including sophisticated aspherical, highly polished mirrors.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 163-164
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  • 16
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    Space debris impact experiment (S0001) (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The specific objectives of this experiment are to establish the population and size distribution of meteoroids in the mass range from 10 to the minus 10 power to 10 to the minus 4 power G, to establish the current population of man-made debris in the same mass range, and to obtain data on the physical properties (composition and density) of meteoroids.
    Keywords: ASTROPHYSICS
    Type: Long Duration Exposure Facility (LDEF); p 136-137
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  • 17
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    Holographic data storage crystals for LDEF (A0044) (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Electro-optic holographic recording systems were developed. The spaceworthiness of electro-optic crystals for use in ultrahigh capacity space data storage and retrieval systems are examined. The crystals for this experiment are included with the various electro-optical components of LDEF experiment. The effects of long-duration exposure on active optical system components is investigated. The concept of data storage in an optical-phase holographic memory is illustrated.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 152-153
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  • 18
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    Interplanetary dust experiment (A0201) (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The objective of this experiment is to study interplanetary dust, variously referred to as cosmic dust, cometary dust, zodiacial dust, or meteoric dust particles. Specific objectives are to obtain information regarding particle mass and velocity, and to undertake correlative analyses with other experiments, both on LDEF or near the time of the LDEF flight.
    Keywords: ASTROPHYSICS
    Type: Long Duration Exposure Facility (LDEF); p 134-135
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  • 19
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    Attempt at dust debris collection with stacked detectors (A0138-2) (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The primary objective of this experiment is to investigate the feasibility of future missions of multilayer thin-film detectors acting as energy sorter to collect micrometeoroids, if not in their original shape, at least as fragments suitable for chemical analysis. It is expected that this kind of particle collector will help in solving one of the most puzzling topics in cosmic-dust studies: the mineralogical and chemical composition of the particles. This is a matter of great interest in the study of the origin and evolution of the solar system.
    Keywords: ASTROPHYSICS
    Type: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 124-126
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  • 20
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    Multiple-foil microabrasion package (A0023) (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The specific scientific objectives of this experiment are to measure the spatial distribution, size, velocity, radiance, and composition of microparticles in near-Earth space. The technological objectives are to measure erosion rates resulting from microparticle impacts and to evaluate thin-foil meteor 'bumpers'. The combinations of sensitivity and reliability in this experiment will provide up to 1000 impacts per month for laboratory analysis and will extend current sensitivity limits by 5 orders of magnitude in mass.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 117-120
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  • 21
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    Flight test of a synthetic aperture radar antenna using STEP (1984)
    In:  CASI
    Details
    Publication Date: 2006-04-03
    Description: To establish confidence in its overall performance, credible information on the synthetic aperture radar antenna's mechanical properties in orbit must be obtained. However, the antenna's size, design, and operating environment make it difficult to simulate operating conditions under 1-g Earth conditions. The Space Technology Experiments Platform (STEP) offers a timely opportunity to mechanically qualify and characterize the antenna design in a representative environment. The proposed experimental configuration would employ a half-system of the full-scale RADARSAT antenna which would be mounted on the STEP platform in the orbiter cargo bay such that it could be deployed and retracted in orbit (as shown in this figure). The antenna would be subjected to typical environmental exposures while an array of targets and sensors on the antenna support structure and reflecting surface are observed and monitored. In particular, the typical environments would include deployment and retraction, dynamic response to vehicle thruster or base exciter inputs, and thermal soak and transient effects upon entering or exiting Earth eclipse. The proposed experiment would also provide generic information on the properties of large space structures in space and on techniques to obtain the desired information.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA. Langley Research Center STEP Expt. Requirements; p 339-354
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  • 22
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    A comparison of lightning and nuclear electromagnetic pulse response of tactical shelters (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The internal response (electromagnetic fields and cable responses) of tactical shelters is addressed. Tactical shelters are usually well-shielded systems. Apart from penetrations by signal and power lines, the main leakage paths to the interior are via seams and the environment control unit (ECU) honeycomb filter. The time domain in three-dimensional finite-difference technique is employed to determine the external and internal coupling to a shelter excited by nuclear electromagnetic pulses (NEMP) and attached lightning. The responses of interest are the internal electromagnetic fields and the voltage, current, power, and energy coupled to internal cables. Leakage through the seams and ECU filter is accomplished by their transfer impedances which relate internal electric fields to external current densities. Transfer impedances which were experimentally measured are used in the analysis. The internal numerical results are favorably compared to actual shelter test data under simulated NEMP illumination.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA. Langley Research Center Intern. Aerospace and Ground Conf. on Lightning and Static Elec.; 12 p
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  • 23
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    Lightning research: A user's lament (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: As a user of devices and procedures for lightning protection, the author is asking the lightning research community for cookbook recipes to help him solve his problems. He is lamenting that realistic devices are scarce and that his mission does not allow him the time nor the wherewithal to bridge the gap between research and applications. A few case histories are presented. In return for their help he is offering researchers a key to lightning technology--the use of the Eastern Test Range and its extensive resources as a proving ground for their experiment in the lightning capital of the United States. A current example is given--a joint lightning characterization project to take place there. Typical resources are listed.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: NASA. Langley Research Center Intern. Aerospace and Ground Conf. on Lightning and Static Elec.; 6 p
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  • 24
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    Upset susceptibility study employing circuit analysis and digital simulation (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: An approach to predict the susceptibility of digital systems to signal disturbances is described. Electrical disturbances on a digital system's input and output lines can be induced by activities and conditions including static electricity, lightning discharge, electromagnetic interference (EMI), and electromagnetic pulsation (EMP). The electrical signal disturbances employed for the susceptibility study were limited to nondestructive levels, i.e., the system does not sustain partial or total physical damage and reset and/or reload brings the system to an operational status. The front-end transition from the electrical disturbances to the equivalent digital signals was accomplished by computer-aided circuit analysis. The super-sceptre (system for circuit evaluation of transient radiation effects) programs was used. Gate models were developed according to manufacturers' performance specifications and parameters resulting from construction processes characteristic of the technology. Digital simulation at the gate and functional level was employed to determine the impact of the abnormal signals on system performance and to study the propagation characteristics of these signals through the system architecture. Example results are included for an Intel 8080 processor configuration.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Intern. Aerospace and Ground Conf. on Lightning and Static Elec.; 14 p
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  • 25
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    A comparison of lightning and nuclear electromagnetic pulse response of a helicopter (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A numerical modeling technique is utilized to investigate the response of a UH-60A helicopter to both lightning and nuclear electromagnetic pulses (NEMP). The analytical approach involves the three-dimensional time domain finite-difference solutions of Maxwell's equations. Both the external currents and charges as well as the internal electromagnetic fields and cable responses are computed. Results of the analysis indicate that, in general, the short circuit current on internal cables is larger for lightning, whereas the open-circuit voltages are slightly higher for NEMP. The lightning response is highly dependent upon the rise time of the injected current as was expected. The analysis shows that a coupling levels to cables in a helicopter are 20 to 30 dB larger than those observed in fixed-wing aircraft.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA. Langley Research Center Intern. Aerospace and Ground Conf. on Lightning and Static Elec.; 7 p
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  • 26
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    Data and results of a laboratory investigation of microprocessor upset caused by simulated lightning-induced analog transients (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Advanced composite aircraft designs include fault-tolerant computer-based digital control systems with thigh reliability requirements for adverse as well as optimum operating environments. Since aircraft penetrate intense electromagnetic fields during thunderstorms, onboard computer systems maya be subjected to field-induced transient voltages and currents resulting in functional error modes which are collectively referred to as digital system upset. A methodology was developed for assessing the upset susceptibility of a computer system onboard an aircraft flying through a lightning environment. Upset error modes in a general-purpose microprocessor were studied via tests which involved the random input of analog transients which model lightning-induced signals onto interface lines of an 8080-based microcomputer from which upset error data were recorded. The application of Markov modeling to upset susceptibility estimation is discussed and a stochastic model development.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Intern. Aerospace and Ground Conf. on Lightning and Static Elec.; 12 p
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  • 27
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    Real-time synthetic aperture radar processing (1984)
    In:  CASI
    Details
    Publication Date: 2006-04-09
    Description: Real-time acousto-optic SAR processors are described and experimentally demonstrated. SAR imaging is performed in one of the architectures by applying the signal to an acousto-optic device and correlating it with chirp signals recorded on an optical transparency by time integration on a CCD detector. In a different implementation, the imaging is preformed by interfering the light beams diffracted from two separate acousto-optic devices, one modulated the radar signal and the second by the reference chirp waveform.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA. Langley Research Center Opt. Inform. Process. for Aerospace Appl. 2; p 199-213
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  • 28
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    Microwave reflector characterization using simple instruments in EVA (1984)
    In:  CASI
    Details
    Publication Date: 2006-04-03
    Description: An antenna with rigid panels which can be measured under ground conditions, carried to space in a packaged condition, deployed into a form similar to the Earth-measured one, measured under space conditions, restowed, and brought back to Earth so that the original measurements can be verified is the type being proposed for this experiment. The antenna chosen will be measured under ground conditions, carried aloft, deployed into its antenna shape, lifted by the remote manipulator system to a position where it can be sighted by two astronauts at the two theodolites, and held there until the surface characterization can be completed. An alternate method would be to use photogrammetry and take pictures of the surface from the payload handling station. After the surface characterization is completed, the antenna will be folded and restowed into the Shuttle bay for return to Earth. The surface characterization will be repeated on Earth after its return for verification both of the original measurement taken on Earth and the measurement taken in space.
    Keywords: COMMUNICATIONS AND RADAR
    Type: STEP Expt. Requirements; p 333-338
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  • 29
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    Adaptive microwave reflector (1984)
    In:  CASI
    Details
    Publication Date: 2006-04-03
    Description: As an interim step in going to the 100-meter reflector that was evaluated, a 5-meter reflector is proposed to test the electrostatic concept under space conditions. Some of the issues which require the space environment for evaluation are the following questions: Can deployment of a box ring structure with a thin film reflector attached be manually deployed? In the absence of humidity, can a 0.3-mil aluminized Kapton film reflector be formed by the electrostatic process suitable for antenna applications? Can the photogrammetric process be used to evaluate the reflector surface with pictures taken from the payload handling station? Can the space charging effect be evaluated with the 5-meter reflector attached to the Shuttle? Does the outgassing of moisture from 0.3-mil Kapton film affect its reflector capability? A box ring truss support structure and an automatic sequence deployment system are discussed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: STEP Expt. Requirements; p 325-331
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  • 30
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    Computer simulation of the effects of transmission-averaging in microdensitometry (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: One of the principal advantages of electrography when compared to photography is the nearly linear relationship between source intensity versus resulting image density. This property allows for simplified and more accurate photometric calibration and permits a certain degree of extrapolation of the calibration to beyond the limits of the faintest photoelectric standard on an exposure. The desires to extract quantitative photometric information from electrographic (or photographic) negatives and to convert this information into a digital format for computer analysis or enhancement led to the widespread use of scanning microdensitometers to perform this A-to-D conversion. Therefore it is of vital importance to understand and, if practical, to avoid any nonlinearities which may be introduced during microdensitometry of electrographic emulsions.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 429-431
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    The role of the Automated Plate Measuring (APM) machine in developing a program to discover QSOs automatically (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The scanning of a direct plate with the automatic plate measuring machine which results in the automated selection and description of images is described. The selection of QSO candidates based on color-color diagrams constructed from the APM image data and the analysis of APM raster data for QSOs selected visually from objective prism plates are also discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 417-418
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  • 32
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    Next generation microdensitometer (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The fundamental limitations of microdensitometers are reviewed and the design of a high microdensitometer described. The system will digitize to 16 bits in transmission at a speed of 100 kHz using a laser beam moving over the emulsion. Other features are automatic platen rotation and autofocus. The cost will be of order $200,000.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 333-341
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  • 33
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    A new measuring machine in Paris (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A new photographic measuring machine is under construction at the Paris Observatory. The amount of transmitted light is measured by a linear array of 1024 photodiodes. Carriage control, data acquisition and on line processing are performed by microprocessors, a S.E.L. 32/27 computer, and an AP 120-B Array Processor. It is expected that a Schmidt telescope plate of size 360 mm square will be scanned in one hour with pixel size of ten microns.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 329-332
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  • 34
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    A preliminary analysis of a diode array for densitometry (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A diode-array based image digitizer manufactured by the Eikonix Corp. was tested to see if it can be adapted to the exacting requirements of astronomical densitometry. As the device is presently configured, a dynamic range of 400:1 can be achieved routinely, with a positional accuracy of 2 microns or better. An area of 2048 X 2048 pixels can be scanned in about 5 minutes. Preliminary tests indicate that several relatively simple enhancements can improve both the photometric and the positional accuracy of the device.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 307-315
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  • 35
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    A next generation microdensitometer? (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Motivations for construction of a next generation microdensitometer (NGM) are presented and their effect on the NGM design is discussed. A prototype of such an engine has been constructed at KPNO. Its design and performance is reviewed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 291-305
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  • 36
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    Why use a microdensitometer other than a PDS? (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The motivations for constructing a special purpose built microdensitometer are explored. The salient points of some of the microdensitometers are described and the advantages and disadvantages of the system in comparison to a PDS machine are outlined. The principal gain is in speed though at the expense of loss in dynamic range. The effects on the astronomical results are demonstrated. The astronomical results already obtained with these machines and from ongoing projects are described. It is shown that there is a large class of important astronomical problems which can be tackled by these machines but which are not feasibile on the PDS because of the speed of the machine.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 209-228
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  • 37
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    Improvements to the Photometric response and positional accuracy of the Yale PDS 2020G microdensitometer (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The necessity to incorporate several hardware changes to optimize the Yale PDS 2020G microdensitometer for photometric and astrometric research are discussed. The properties of a new high speed photometer and a positional calibration system are described. The new photometer incorporates a high speed logarithmic analog to digital converter with more than 10 times the resolution of the former system and a cycle time of approximately 50 usec. The positional calibration system monitors the drunkenness of the stages with respect to fixed index lines and enables the correction of the +/- 5 micro stage errors to an accuracy of better than 1 micro.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 151-161
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  • 38
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    Performance of the ESO PDS (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The astrometric and photometric performance of the PDS 1010A microdensitometer are discussed, including the tests used for checking it. The instrument was shown to satisfy operational requirements for photometric measurements of astronomical plates with respect to dynamic range and stability.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 89-95
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  • 39
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    Characteristics of the MSFC, PDS microdensitometer (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The results of several parametric studies carried out on the Marshall Space Flight Center (MSFC) Photometric Data System PDS-10 microdensitometer are summarized for the purposes of documenting the operation and limitations of the system for inhouse research and to provide a bench mark for comparison with other microdensitometers. The results are grouped into four general areas. These are: (1) system overall stability to drift, (2) photometric linearity and noise, (3) reproducibility, and (4) scanning performance. Test data taken in order to evaluate the interdependency of scan speed, noise and position are included. Shown also are results of tests for system stability, reproducibility, stray light and PMT settling time.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Marshall Space Flight Center Astron. Microdensitometry Conf.; p 71-88
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  • 40
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    Microdensitometer errors: Their effect on photometric data reduction (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The performance of densitometers used for photometric data reduction of high dynamic range electrographic plate material is analyzed. Densitometer repeatability is tested by comparing two scans of one plate. Internal densitometer errors are examined by constructing histograms of digitized densities and finding inoperative bits and differential nonlinearity in the analog to digital converter. Such problems appear common to the four densitometers used in this investigation and introduce systematic algorithm dependent errors in the results. Strategies to improve densitometer performance are suggested.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 45-58
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  • 41
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    Experiences with a PDS 2020 GM (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Various perturbations which occurred during the operation of a PDS 2020 GM microdensitometer are reviewed. The effects of elevated temperature, vibration, transient electrical noise, and photometric perturbations are briefly discussed. Sample astronomical results from the PDS 2020 GM unit are presented.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 97-106
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  • 42
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    Positive-feedback photometric drift in the PDS (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Digitizing flatfield images produces conditions in the Photometric Data System PDS which cause the measured density to drift by as much as .1 DN during a 10 minute interval. The drift occurs when the PDS, set up in equilibrium at fog level, subsequently scans a reasonably dense region for periods of longer than a few minutes. The drift is manifested primarily as a positive shift in density that is approximately the same for all densities. If the fog level is assumed to be in fact constant and is monitored during scans of flat fields, the PDS drift may be removed by subtracting the difference between the observed fog level and its assumed constant value for each pixel. This function is then smoothed and subtracted, as a function of scan line, from the measured density. The fog level is then adjusted to a standard value by adding a constant. The result is a flattened scan with PDS drift removed to the accuracy within which the fog level drift matches the drift at other levels.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Astron. Microdensitometry Conf.; p 59-69
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  • 43
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    Photometric and positional accuracy of the PDS Bonn in view of astronomical requirements (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The photometric and positional accuracy of a microdensitometer is examined. A calibrating plate with different density areas available is used to determine photometric accuracy. Position accuracy is evaluated by multiple scans of sharp edges and analyzed statistically.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 35-43
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  • 44
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    LDEF thermal measurements system (P0003) (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Many of the passive experiments flying on LDEF will be significantly enhanced if data are available postflight to indicate the temperature time histories of test materials and other specimens exposed in the experiments. The baseline LDEF approach was to provide postflight calculated temperature histories of experiment boundaries and solar flux data for the mission, which can in turn be used by each investigator to calculate the temperature time histories for critical experiment components. Without in-flight temperature measurements, a substantial uncertainty will exist in the calculated temperatures. The data measured by the themal measurement system (THERM) will significantly improve postflight knowledge of temperatures experienced by LDEF experiments. The THERM data will also be valuable in validating the LDEF thermal design concept and in providing better design data for experimenters on future LDEF missions. The objectives of this experiment are to determine the history of the interior average temperatures of the LDEF for the total orbital mission and to measure the temperatures of selected components and thermal boundary conditions.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Long Duration Exposure Facility (LDEF); p 78-81
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  • 45
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    Effect of space environment on space-based radar phased-array antenna (A0133) (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Kapton polyimide film was selected as the baseline material for the Grumman spce based radar (SBR) concept. To gain the requisite confidence for long-term service durability, it is desirable to subject material specimens as well as a portion of the SBR antenna directly to the combined space environment and compare property degradation to that caused by laboratory simulation. The overall objective of this program is to evauate the effect of the space environment on polymeric materials currently being considered for the Grumman SBR Phased-Array Antenna. Degradation mechanisms caused by thermal cycling, ultraviolet and charged-particle irradiation, applied load, and high-voltage plasma interaction will be evaluated. The experiment occupies a 6-in.-deep end corner tray located on the space end of the Long Duration Exposure Facility and consists of both passive and active parts. The passive part addresses the effect of environment and stress on the dimensional stability spliced and continuous Kapton, both plain and reinforced. The active part will study the interaction of high voltage and low-Earth-orbit plasma.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 21-23
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  • 46
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    Interstellar-gas experiment (A0038) (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The objectives of this experiment are to collect and isotopically analyze interstellar gas atoms around the orbit of the Earth for the purpose of obtaining new data relevant to understanding nucleosynthesis, and to study the dynamics of the interstellar wind inside the heliosphere and the isotopic composition of the interstellar medium outside the heliosphere. The experiment hardware will act as a set of simple cameras with high-purity copper-beryllium collecting foils serving as the film. The experiment housing will mount and thermally control the foils, establish the viewing angles and viewing direction, provide baffling to reject ambient neutral particles, provide a voltage grid to reject ionospheric charged particles, sequence collecting foils, control exposure times, and protect the foils from contamination during the deployment and retrieval of the LDEF. After being returned to Earth, the entrapped atoms can be analyzed by mass spectroscopy to determine the relative abundance of the different isotopes of helium and neon. An attempt will also be made to detect argon.
    Keywords: ASTROPHYSICS
    Type: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 98-100
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  • 47
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    Tropospheric calibration in radio interferometry (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A new tropospheric mapping function is derived which is more accurate than previous mapping functions above elevations of 4 deg. The error due to the given analytic aproximation is estimated to be less than 0.2 percent for elevation angles larger than 6 deg (less than 0.4 cm at 6 deg). The mathematical expansion used in the derivation is valid for any laterally homogeneous atmospheric model of refractivity. The new mapping function, computer-generated ray tracing tables, and other mapping functions are compared.
    Keywords: COMMUNICATIONS AND RADAR
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  • 48
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    Some aspects of understanding changes in the global carbon cycle (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The collective character of carbon exchanges between the atmosphere and other pools is partially revealed by comparing the record of CO2 concentration beginning in 1958 with estimates of the releases from fossil fuels during this period. In analyzing the secular increase in CO2 concentration induced by fossil fuel use, the atmosphere is generally treated as a single well-mixed reservoir; however, to study finer structure in the CO2 records, the influence of atmospheric circulation must be more carefully considered. The rate of carbon uptake by the oceans, the primary sink for fossil fuel CO2, is assessed more reliably than influences on the atmosphere due to interactions with other pools. Models of the global carbon cycle are being substantially refined while data that reflect the response of the cycle to fossil fuel use and other perturbations are being extended.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: JPL The interaction of Global Biochemical Cycles; p 55-84
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  • 49
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    A statistical correlation method for the retrieval of atmospheric moisture profiles by microwave radiometry (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A statistical correlation technique is applied to the retrieval of vertical moisture profiles under clear-sky conditions from down-looking radiometric measurements of atmospheric radiation at microwave wavelengths. For a given set of channels, the method selects the optimum radiometric channels for estimating water vapor at specific pressure levels between the surface and 300 mb. The water vapor mixing ratio at these pressure levels is then calculated from a linear combination of the selected channel brightness temperatures. To test its validity the algorithm was applied, in a numerical experiment, to fifty independent tropical radiosondes. The rms absolute deviation of the estimated moisture profiles from the actual profiles was comparable to that obtained using an iterative retrieval method reported earlier. The statistical method, however, requires several orders of magnitude less computer time than the iterative method; it is suitable for high speed processing of large amounts of data.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Climate and Applied Meteorology (ISSN 0733-3021); 23; 1110-111
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  • 50
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    High spatial resolution IR observations of young stellar objects - A possible disk surrounding HL Tauri (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: High spatial resolution images of the T Tauri star HL Tau were obtained at 1.6 microns and 2.2 microns. The original images as well as maximum entropy image reconstructions reveal a circumstellar envelope structure, similar at both wavelenghts, and extended along P.A. = 112 deg; the 10 percent width of the structure is 1.9 sec (300 AU at 160 pc). The extended structure is interpreted as light scattered toward earth by dust in a disk surrounding this young stellar object. Polarization measurements made at 2.2 microns support this hypothesis. The total solid particle mass is, at minimum, 5 x 10 to the -7th solar mass.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 283; L57-L61
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  • 51
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    Problems in simulating the stratocumulus-topped boundary layer with a third-order closure model (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The Andre et al. (1976, 1978) third-order closure model, in which the time rate of change terms, the relaxation and rapid effects for pressure-related terms, and the clipping approximation are used along with the quasi-normal closure, is invoked in the study of turbulence in a cloudy layer that is radiatively cooled from above. A spurious oscillation whose greatest amplitude lies near the inversion is shown by analysis to arise from the mean gradient and buoyancy terms of the triple-moment equations. An attempt is made to damp the oscillation through the introduction of diffusion terms into the triple-moment equations. The results obtained are noted to be sensitive to the ad hoc eddy coefficient applied in the third-moment equations.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of the Atmospheric Sciences (ISSN 0022-4928); 41; 1588-160
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  • 52
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    Very slow classical Cepheids - Theoretical models with periods longer than 50 days (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Systematics of the light curves of classical Cepheids with the longest known periods have been investigated with the help of full-amplitude models of pulsating stellar envelopes. For periods exceeding about 60 days, flat-topped light curves of the S Vul type are found to replace the smooth, asymmetric light curves characteristic of the slightly faster Cepheids. Predicted light and velocity amplitudes (although not the predicted radius amplitudes) agree well with observations. Variables with fluctuating light minima are observed to lie well off the mean period-luminosity relation, as are a few other (more stable?) variables with similarly long periods. The explanation for the long periods is probably low effective temperature rather than a low stellar mass. Because of the abnormal slowness of the classical Cepheids with periods longer than about 100 days, it is recommended that these variables not be used to calibrate the mean period-luminosity relation. Analogies between the slow classical Cepheids and the slow Population II Cepheids are drawn.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 281; 811-814
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  • 53
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    On the '3 kiloparsec arm' - Resonance excitation of linear and nonlinear waves by an oval distortion in the central region (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The mechanism responsible for the massive rapidly expanding Galactic feature known as the 3-kpc arm (Rougoor and Oort, 1960) is investigated theoretically in the framework of a density-wave model of the Galaxy. The arm is attributed to outgoing waves excited at the outer Lindblad resonance (OLR) of a small rotating oval distortion near the Galactic center. Linear and nonlinear models are developed, and it is shown that a density crest at 3.5 kpc with expansion velocity 53 km/s can be generated by a distortion turning at 118 km/s kpc with a 10-percent perturbation of the main gravitational field at the OLR (located at 3 kpc). The wave character of the nonlinear solution is found to be the same as that of the linear solution and to give good agreement with the observations in terms of expansion velocity, size, shape, and mass; only the observed asymmetry of the arm is not reproduced.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 281; 600-613
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  • 54
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    Superclustering and the large-scale structure of the Universe (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A complete redshift survey of nearby rich galactic clusters is analyzed in terms of a spatial correlation function, the growth of supercluster, the presence of superclusters around the Bootes void and the discovery of a 300 Mpc void. Abell's (1958) statistical sampling of rich clusters is used for the study. Attention is given to the dependence of the correlation function on the richness of the system, with finding that chances are greater of finding rich neighbors closer together than poor neighbors. Samples of redshifts of 4 or less correlate well with clusters of redshift 5 or more. The size of intergalactic voids is proportional to the surrounding galactic excesses. Finally, the superclusters exist on scales of about 100 Mpc/h, which is larger than expected.
    Keywords: ASTROPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 3; 10-12
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  • 55
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    Reduction of flow-measurement uncertainties in laser velocimeters with nonorthogonal channels (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Previously cited in issue 5, p. 642, Accession no. A83-16486
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: AIAA Journal (ISSN 0001-1452); 22; 1115-112
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  • 56
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    Ultraviolet spectral morphology of the O stars - The remarkable luminosity dependence of the Si IV stellar wind effect (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: An extensive survey of ultraviolet O type spectra, by means of high-resolution data from the International Ultraviolet Explorer archives, shows a strong correlation between both the photospheric and stellar wind features, and the optical spectral types. In particular, the stellar wind effect in the Si IV resonance doublet displays a strong luminosity dependence which has not been completely described before: there is no effect anywhere on the main sequence, but it develops gradually through the intermediate luminosity classes into a full P Cygni profile in the supergiants. This behavior is in sharp contrast to that of the C IV and N V, which have strong P Cygni profiles throughout most of the O type domain, including the main sequence. The Si IV effect simultaneously provides a sensitive classification criterion and poses an outstanding problem for detailed astrophysical interpretation. In addition, a new emission feature at 1574 A, possibly due to N III or to N IV forbidden line, is reported.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 280; L27-L30
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  • 57
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    Do bipolar magnetic regions exist on the surfaces of early-type stars? (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The observations of relatively narrow absorption components of the UV resonance lines in the spectra of early-type stars are reviewed, and some new observational data are presented for Rho Leo (B1 Ib). It is shown that the discrete components which are seen in the UV resonance lines of early-type stars are a result of ejection from local spots above the photospheres of hot stars. It is suggested that localized ejection is caused by magnetic flux lines associated with a bipolar magnetic region on the surface of the star.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 280; 712-728
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  • 58
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    Models of the hard X-ray spectrum of AM Herculis and implications for the accretion rate (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Phenomenological fits to the hard X-ray spectrum of AM Hercules have failed to explain the high equivalent width (0.8 + or - 0.1 keV) of Fe K-alpha emission. The scattering and fluorescent line production in a cold or partially ionized accretion column of hard X-rays emitted at the base are investigated using the Monte Carlo method. It is shown that the Fe emission equivalent width observed in the spectrum of AM Her can be explained without resorting to an overabundance of Fe in the accreting material. For sufficient optical depth across the accretion column, equivalent widths of K-alpha emission even larger than the observed values can be obtained. The accretion rate and gravitational power can be deduced from the optical depth across the column, if the column size is known, and, together with the observed hard X-ray and polarized light luminosities, imply a lower limit for the luminosity in the UV to soft X-ray range, for which the observations give model-dependent values.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 280; 734-743
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  • 59
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    Disappearance and disintegration of comets (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The present investigation has the objective to provide a summary of the existing evidence on the disappearance of comets and to draw conclusions regarding the physical processes involved in the disappearance. Information concerning the classification of evidence and the causes of apparent disappearance of comets is presented in a table. Attention is given to the dissipating comets, the headless sungrazing comet 1887 I, and the physical behavior of the dissipating comets and the related phenomena. It is found that all comets confined to the planetary region of the solar system decay on astronomically short time scales. However, only some of them appear to perish catastrophically. Some of the observed phenomena could be successfully interpreted. But little insight has been obtained into the character of the processes which the dissipating comets experience.
    Keywords: ASTROPHYSICS
    Type: Icarus (ISSN 0019-1035); 58; 81-100
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    X-ray spectral signatures of accreting black holes (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The X-ray properties of the binary black hole candidates include distinctive bimodal spectral behavior where the X-ray spectra switch between being very soft (alpha greater than 3) and hard (alpha about 0.7). It is pointed out that this spectral transition occurs at about 1 percent L(edd) (for accretion onto a 10 solar masses black hole), and that this corresponds to the luminosity where an optically thick electron-positron pair plasma will form. Active galactic nuclei (AGN) are often considered to be accreting black holes. An X-ray spectral similarity between the above binary sources and both the Seyfert I and BL Lac classes of AGN is demonstrated. As many of these objects radiate most of their luminosity as X-rays, such a similarity may be expected if the underlying mechanisms are similar.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 133; 2, Ap
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    Lightning activity and severe storm structure (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Space-time mapping of VHF sources from four severe storms on June 19, 1980 reveals that lightning processes for cloud-to-ground (CG) and large intracloud (IC) flashes are confined to an altitude below about 10 km and closely associated with the central regions of high reflectivity. Another class of IC flashes produces a splattering of sources within the storms' main electrically active volumes and also within the large divergent wind canopy aloft. There is no apparent temporal association between the small high altitude IC flashes that occur almost continuously and the large IC and CG flashes that occur sporadically in the lower portions of storms.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Geophysical Research Letters (ISSN 0094-8276); 11; 545-548
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    Spectral analysis of magnetohydrodynamic fluctuations near interplanetary shocks (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Preliminary results of an investigation of magnetic fluctuations seen upstream of two interplanetary shocks are presented. The spectral analysis includes calculation of the normalized reduced magnetic helicity spectrum, the normalized reduced cross-helicity spectrum, and the Alfven ratio as discussed by Matthaeus and Goldstein (1982). Minimum variance methods are used to compute wave polarization as a function of frequency. The Taylor 'frozen in flow' hypothesis is assumed to convert frequencies to wave vectors. Some of the basic properties of the waves, including the probable mode of propagation in association with both quasi-parallel forward and reverse shocks, are described. A comparison with previous results on the generation of waves at interplanetary and planetary shocks is presented.
    Keywords: ASTROPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 89; 3762-377
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    A variational formulation for time-dependent climate models (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A variational principle for time dependent diffusion problems is presented and is demonstrated by applying it to simple seasonal climate models. Two cases are treated. The first, a North-Coakley-type model with constant properties, is used as a tutorial example for the application of the technique. For the second case, heat capacity and thermal conductivity are considered to be latitude dependent in order to treat the effects of land/ocean distribution on the seasonal temperature distribution over the earth. The variational equations are derived and approximate analytical solutions are developed which delineate the influences of the physical asymmetries of the hemispheres in producing an asymmetric annual cycle.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Geophysical Research (ISSN 0148-0227); 89; 2601-260
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    Requirements for a passive IR advanced moisture and temperature sounder (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The design of a high spectral resolution, lambda/delta lambda being approximately 1200 IR, sounder capable of increasing the vertical resolution of atmospheric temperature profiles and achieving a rms accuracy of approximately 1.5 K is discussed. This sounder permits improved determination of meteorological parameters on cloudiness, surface temperature, and air-surface interactions. A set of channels from the high J lines in the R branch of the 4.3-micron CO2 band complemented by a larger set of window, humidity, and temperature channels in the 3.7-, 6.3-, 9-, and 15-micron regions is used. Design and simulation studies show that such a sounder is within the present state of the art.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 23; 979-989
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    Solar disk sextant (1984)
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    Publication Date: 2011-08-18
    Description: This paper presents the conceptual design of an instrument, called the solar disk sextant, to be used in space to measure the shape and the size of the sun and their variations. The instrumental parameters required to produce sufficient sensitivity to address the problems of solar oblateness, solar pulsations, and global size changes of climatic importance are given.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 23; 1235-123
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    Analogs in the wintertime 500 mb height field (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Lorenz (1969) has considered the possibility that an atmospheric circulation pattern might recur, taking into account the definition of a pair of analogous flows or 'analogs'. The present investigation is concerned with a search of time series of Northern Hemisphere wintertime geopotential heights for possible analogs. Attention is given to data and analysis procedure, analog quality, and error growth rates. The obtained results imply that the found analogs are not a useful tool for forecasting the evolution of the midlatitude flow on time scales of several days. It is pointed out, however, that the negative results should not be extended to other applications of analog forecasting.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of the Atmospheric Sciences (ISSN 0022-4928); 41; 177-189
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    HEAO 3 observations of the Crab pulsar (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The Crab pulsar (PSR 0531+21) is the only pulsar which has been observed throughout almost the entire electromagnetic spectrum from 0.5 keV to over 2000 GeV. In general, the emission from the Crab nebula and its pulsar has been remarkably constant in time (except for the pulsations). However, several recent observations, especially of gamma-ray line emission, indicate possible time variations. The present investigation is concerned with the data obtained with the HEAO C-1 experiment. The data have been studied with the hope of finding information regarding a number of questions, taking into account the existence of line emission from the pulsar, the variation of the shape of the light curve with time, and the spectral variations as a function of pulsar phase. The spectrum of the total phase-averaged pulsed emission is found to be consistent with a single power-law spectrum from 50 keV to 10 MeV.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 278; 784-790
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    X-ray observations of X Persei (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The HEAO 2 Einstein Observatory was used to confirm the identification of 4U 0352 + 30 with X Per. The HEAO 2 data were analyzed in order to determine an additional point in the pulse period history of the X-ray source and to search for short binary periods. In addition, a majority of the historical X-ray observations was reanalyzed and more refined values for the pulse period as a function of time were obtained. The period history possess significant scatter, but no evidence for a measurable long-term spin-up trend is found, and hence a lower limit to the spin-up time scale is set. This lower limit is consistent with the presence of a neutron star, but it does not rule out a degenerate dwarf. The period history was also searched for evidence of binary motion, and upper limits to a(x) sin i were obtained.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 278; 711-715
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    Variable ultraviolet emission in SY Muscae (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The results of continued IUE monitoring of the symbiotic variable SY Muscae, following an earlier report of a radical enhancement in UV emission from the star, are reported. Over the course of one year, the prominent emission lines of N V, O V, C IV, and He II appear to be gradually decreasing in absolute intensity. This appears to coincide with a steady decline in electron density in the emission line forming region. The data are consistent with a sudden ejection event in which material expelled from the surface of a hot subdwarf has exposed the underlying UV continuum of the star. A number of strong emission lines that are photoexcited by the intense radiation field of the secondary also exhibit broad pedestal emission that suggests turbulent velocities of about 150-300 km/s in an expanding shell or possibly in an accretion disk.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 207; 575-583
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    A laser interferometer for measuring skin friction in three-dimensional flows (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Previously cited in issue 05, p. 643, Accession no. A83-16685
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: AIAA Journal (ISSN 0001-1452); 22; 557-559
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    The remarkable ultraviolet spectrum of the planetary nebula Abell 30 (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Abell 30 has been identified as a planetary nebula in which the nucleus has experienced a final helium shell flash after ejection of the original, outer envelope. Around the central star of the nebula, four knots of material are observed. In view of the importance of the chemical composition of the ejected material for studies of advanced stages of stellar evolution, clarification of the physical conditions in the knots is vital. Data obtained of Abell 30 with the aid of the International Ultraviolet Explorer (IUE) satellite are discussed along with aspects of extinction, the He II flux, ionic abundances, the C II lambda 4267 line, questions regarding the existence of a carbon-rich core in the knot, the heating of the nebular gas, the central star, and heating by suprathermal particles from the stellar wind. The UV spectrum of the inner nebulosity of Abell 30 indicates that an extraordinary amount of energy is being deposited in the gas.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 277; 716-724
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  • 72
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    Simple high-temperature thermal diffusivity apparatus (1984)
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    Publication Date: 2011-08-18
    Description: A simple and inexpensive thermal diffusivity apparatus is described for measurement up to 1600 K. The novel features of apparatus include a light pipe, a long furnace, and a differential thermocouple. A low heat-load sample holder for clamping the sample in a vertical position is also described. The results of measurements on AXM-5Q graphite are reported.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments (ISSN 0034-6748); 55; 235-237
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  • 73
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    Highlights of the Symposium on the Multiple-Parameter Radar Measurements of Precipitation - Personal reflections. (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Radio Science (ISSN 0048-6604); 19; 238-242
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    A study of extreme carbon stars. I - Silicon carbide emission features (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: 10-micron spectra of many extreme carbon stars reveal a prominent emission feature near 11 microns. This is compared with laboratory spectra of SiC grains. Two distinct types of features are found, perhaps indicative of different mechanisms of grain formation in different stars. Estimates are made of probable column densities and total masses of SiC in the circumstellar shells.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 206; 137-147
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    Differential detection of Gaussian MSK in a mobile radio environment (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Minimum shift keying with Gaussian shaped transmit pulses is a strong candidate for a modulation technique that satisfies the stringent out-of-band radiated power requirements of the mobil radio application. Numerous studies and field experiments have been conducted by the Japanese on urban and suburban mobile radio channels with systems employing Gaussian minimum-shift keying (GMSK) transmission and differentially coherent reception. A comprehensive analytical treatment is presented of the performance of such systems emphasizing the important trade-offs among the various system design parameters such as transmit and receiver filter bandwidths and detection threshold level. It is shown that two-bit differential detection of GMSK is capable of offering far superior performance to the more conventional one-bit detection method both in the presence of an additive Gaussian noise background and Rician fading.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Vehicular Technology (ISSN 0018-9545); VT-33; 307-320
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    MHD processes in the outer heliosphere (1984)
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    Publication Date: 2011-08-19
    Description: The magnetic field measurements from Voyager and the magnetohydrodynamic (MHD) processes in the outer heliosphere are reviewed. A bibliography of the experimental and theoretical work concerning magnetic fields and plasmas observed in the outer heliosphere is given. Emphasis in this review is on basic concepts and dynamical processes involving the magnetic field. The theory that serves to explain and unify the interplanetary magnetic field and plasma observations is magnetohydrodynamics. Basic physical processes and observations that relate directly to solutions of the MHD equations are emphasized, but obtaining solutions of this complex system of equations involves various assumptions and approximations. The spatial and temporal complexity of the outer heliosphere and some approaches for dealing with this complexity are discussed.
    Keywords: ASTROPHYSICS
    Type: Space Science Reviews (ISSN 0038-6308); 39; 255-316
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    Cosmogony as an extrapolation of magnetospheric research (1984)
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    Publication Date: 2011-08-19
    Description: A theory of the origin and evolution of the Solar System which considered electromagnetic forces and plasma effects is revised in light of information supplied by space research. In situ measurements in the magnetospheres and solar wind can be extrapolated outwards in space, to interstellar clouds, and backwards in time, to the formation of the solar system. The first extrapolation leads to a revision of cloud properties essential for the early phases in the formation of stars and solar nebulae. The latter extrapolation facilitates analysis of the cosmogonic processes by extrapolation of magnetospheric phenomena. Pioneer-Voyager observations of the Saturnian rings indicate that essential parts of their structure are fossils from cosmogonic times. By using detailed information from these space missions, it is possible to reconstruct events 4 to 5 billion years ago with an accuracy of a few percent.
    Keywords: ASTROPHYSICS
    Type: Space Science Reviews (ISSN 0038-6308); 39; 65-90
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    The small ice cap instability in diffusive climate models (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Simple climate models which invoke diffusive heat transport and ice cap albedo feedback have equilibrium solutions with no stable ice cap smaller than a radius of about 20 deg on a great circle. Attention is presently given to a solution of this phenomenon which is physically appealing. The ice-free solution has a thermal minimum, and if the minimum temperature is just above the critical value for ice formation, then the artificial addition of a patch of ice leads to a widespread depression of the temperature below the critical freezing temperature. A second stable solution will then exist whose spatial extent is determined by the range of the influence function of a point sink of heat, due to the albedo shift in the patch.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of the Atmospheric Sciences (ISSN 0022-4928); 41; 3390-339
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    Comments on 'Comparative diagnostic case study of east coast secondary cyclogenesis under weak versus strong synoptic-scale forcing' (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A comment is presented on a recent paper by Pagnotti and Bosart (1984) which contrasted different forcing mechanisms for weak and strong cyclones along the east coast of the U.S., and Bosart replies. The comment argues that the paper did not give a clear definition of 'weak' upper-level forcing and did not provide sufficient evidence to support its claim that the return branch of transverse circulations may be coupled to the middle as opposed to the lower troposphere.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Monthly Weather Review (ISSN 0027-0644); 112; 2540
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    The Harp probe - An in situ Bragg scattering sensor (1984)
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    Publication Date: 2011-08-19
    Description: A wave sensor, consisting of parallel, evenly spaced capacitance wires, whose output is the sum of the water surface deflections at the wires, has been built and tested in a wave tank. The probe output simulates Bragg scattering of electromagnetic waves from a water surface with waves; it can be used to simulate electromagnetic probing of the sea surface by radar. The study establishes that the wave probe, called the 'Harp' for short, will simulate Bragg scattering and that it can also be used to study nonlinear wave processes.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Atmospheric and Oceanic Technology (ISSN 0739-0572); 1; 358-371
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    Radiosonde pressure sensor performance - Evaluation using tracking radars (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The standard balloon-borne radiosonde employed for synoptic meteorology provides vertical profiles of temperature, pressure, and humidity as a function of elapsed time. These parameters are used in the hypsometric equation to calculate the geopotential altitude at each sampling point during the balloon's flight. It is important that the vertical location information be accurate. The present investigation was conducted with the objective to evaluate the altitude determination accuracy of the standard radiosonde throughout the entire balloon profile. The tests included two other commercially available pressure sensors to see if they could provide improved accuracy in the stratosphere. The pressure-measuring performance of standard baroswitches, premium baroswitches, and hypsometers in balloon-borne sondes was correlated with tracking radars. It was found that the standard and premium baroswitches perform well up to about 25 km altitude, while hypsometers provide more reliable data above 25 km.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Atmospheric and Oceanic Technology (ISSN 0739-0572); 1; 321-327
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    A numerical simulation of barotropic instability. II Wave-wave interaction (1984)
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    Publication Date: 2011-08-19
    Description: A fully nonlinear numerical model of the point jet barotropic instability is used to test and confirm the hypothesis that the magnitude of the wave vorticity does not exceed the magnitude of the initial shear. This result arises directly from the local conservation of vorticity following a parcel and the fact that unstable waves are principally confined to the region where the zonal mean vorticity can be smoothed by the wave so as to eliminate the instability. Comparisons are made between fully nonlinear and quasi-linear models of the point jet instability and their tracer transport properties. Differences become particularly evident after wave saturation. The most important effect neglected by the wave-mean flow model appears to be the advection of wave vorticity by the most unstable mode. However, as equilibration of the instability proceeds, the globally averaged properties of both models are found to be similar.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of the Atmospheric Sciences (ISSN 0022-4928); 41; 2869-288
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    Abundances in galactic H II regions. III - G25.4-0.2, G45.5+0.06, M8, S159, and DR 22 (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Measurements of the ARII (6.99 microns), ArIII (8.99 microns), NeI (12.81 microns), SIII (18.71 microns), and SIV (10.51 microns) lines are presented for five compact HII regions along with continuum spectroscopy. From these data and radio data, lower limits to the elemental abundances of Ar, S, and Ne were deduced. The complex G25.4-0.2 is only 5.5 kpc from the galactic center, and is considerably overabundant in all these elements. Complex G45.5+0.06 is at seven kpc from the galactic center, and appears to be approximately consistent with solar abundance. The complex S159 in the Perseus Arm, at 12 kpc from the galactic center, has solar abundance, while M8 in the solar neighborhood may be somewhat overabundant in Ar and Ne. Complex DR 22, at 10 kpc from the galactic center in the Cygnus Arm, is overabundant in Ar. A summary of results from a series of papers on abundances is given.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 285; 174-180
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    A SAR correlation algorithm which accommodates large-range migration (1984)
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    Publication Date: 2011-08-19
    Description: This paper presents an algorithm for azimuth correlation of synthetic aperture radar (SAR) data with extraordinarily large-range migration which cannot be accommodated by the existing frequency domain interpolation approach used in current Seasat SAR processing. A mathematical model is provided for the SAR range-correlated point-target response both in the spatial and frequency domains. A simple and efficient processing algorithm derived from the exact two-dimensional correlation algorithm is given. This algorithm enables azimuth correlation by two cascaded one-dimensional correlation steps. The first step is to transform the range-correlated SAR data into the frequency domain in azimuth, followed by a newly developed range convolution filter to correct the range-dispersed spectrum of the range-correlated point-target response (RCPTR). The second step is the frequency-domain range migration correction approach for the azimuth compression. Simulation results provided here indicate that this processing algorithm yields a satisfactory compressed impulse response for SAR data with large-range migration whereas previous methods were subject to a broadening of the impulse response along range.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: IEEE Transactions on Geoscience and Remote Sensing (ISSN 0196-2892); GE-22; 592-597
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    Intense X-ray flares from active stellar systems - EV Lacertae and HD 8357 (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The HEAO A-1 Sky Survey Experiment included X-ray data used to define light curves for the flare star EV Lac and for X-ray flares observed in the binary system HD 8357. The data were taken during flare events and were detailed enough to calculate the flare rates and flaring luminosities. The peak luminosities during flares were several times the luminosities in normal X-ray flares emitted by the objects. Peak luminosities reached 30-50 times the normal variations and were associated with an order of magnitude increase in energy output. EV Lac was sufficiently active to be recommended for inclusion in future X-ray monitoring programs.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 284; 270-277
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    Regularized Monte-Carlo calculations of the optical polarization induced by scattering in X-ray binaries (1984)
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    Publication Date: 2011-08-19
    Description: The results of regularized Monte Carlo calculations of the optical polarization Stokes parameters expected as a result of scattering from gas streams or accretion wakes in close binary systems whose properties resemble those of X-ray binaries are presented. The physical processes occurring in the system are represented by a model which follows a selected sample of individual photon paths from each emitting element on the surface of the primary to the photon's detection at earth. The result represents the variations in the intensity from each individual emitting element caused by the effects of limb darkening, gravity darkening, and variation in the projected area of the emitting element as seen from the scattering element.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 138; 1, Se
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    Performance of OOK and low-order PPM modulations in optical communications when using APD-based receivers (1984)
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    Publication Date: 2011-08-19
    Description: The paper computes direct detection laser communications receiver performance when using avalanche photodiode (APD) detectors. The performances are compared in terms of bit error probability vs average signal required per bit when the transmitter uses either on-off keying (OOK) or low-order PPM formats. It is shown that QPPM requires 3 dB less signal than OOK, while BPPM requires the same or slightly more than OOK for the same performance. Optimum APD gain values range from 200 to 400. When using QPPM, k(eff) = 0.006, and optimum gain, 60 signal counts/bit are required at 500 Mbits/s for a 0.000001 bit error probability. It is concluded that QPPM may be an attractive signaling format for some fiber or free space laser communication applications.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Communications (ISSN 0090-6778); COM-32; 1140-114
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    Some aspects of the interannual variation of mean monthly sea level pressure on the Southern Hemisphere (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: We calculate the seasonal changes that are largely associated with the half-yearly wave, autocorrelation functions, and the mean planetary waves in the monthly mean sea level pressure from two data sources. One covers the period from 1951 to 1958 (from the South African Weather Bureau) and the other the period from 1972 to 1980 (from the Australian Bureau of Meteorology). Thirty years of data from stations over the southern hemisphere are used to assess the reliability of the differences between the two periods that the grid-point data show. These differences are especially large over the Atlantic Ocean and the Pacific Ocean. The station data confirm the changes between the two periods and thus the observed differences in the mean waves, which are especially large for wave number 3.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Geophysical Research (ISSN 0148-0227); 89; 9541-954
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  • 89
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    Precession model for the nucleus of periodic Comet Kopff (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The existing data base on certain characteristics of the periodic Comet Kopff, a candidate for a NASA rendezvous mission in the 1990s, is summarized. The comet was discovered in 1906. The data are used to calculate limits to the nuclear mass (0.7-1.5 x 10 to the 16th g), equatorial radius (1.26-1.64 km), and a geometric albedo of 0.08. An equatorial rotation velocity of 8.1-10.7 hr is projected. The estimates are highly dependent on the present photometric data, which in turn depend on the insolation rate, which if different than assumed could mean that all parameters would be revised upward significantly.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal (ISSN 0004-6256); 89; 1573-158
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  • 90
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    The H flux peak and the hydrogen abundance in N type carbon stars (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: For galactic N and late R type irregularly variable carbon stars, a comparison is made of airborne infrared spectrophotometry to spectral flux distributions derived from model atmospheres. Although the agreement is good in several respects, the H(-) emission peak at 1.6 microns, so prominent in the models, is significantly weakened in the stellar spectrophotometry. It seems unlikely that molecular bands in the stars can completely obliterate this peak. A plausible explanation is that hydrogen is deficient in these stars, most probably from an episode of mass loss. The resultant cold shells surrounding these stars should be amenable to observation by IRAS, or other far-infrared observatories.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 284; L39-L42
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  • 91
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    An X-ray survey of variable radio bright quasars (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A sample consisting primarily of radio bright quasars was observed in X-rays with the Einstein Observatory for times ranging from 1500 to 5000 seconds. Detected sources had luminosities ranging from 0.2 to 41.0 x 10 to the 45th power ergs/sec in the 0.5 to 4.5 keV band. Three of the fourteen objects which were reobserved showed flux increases greater than a factor of two on a time scale greater than six months. No variability was detected during the individual observations. The optical and X-ray luminosities are correlated, which suggests a common origin. However, the relationship (L sub x is approximately L sub op to the (.89 + or - .15) found for historic radio variables may be significantly different than that reported for other radio bright sources. Some of the observed X-ray fluxes were substantially below the predicted self-Compton flux, assuming incoherent synchrotron emission and using VLBI results to constrain the size of the emission region, which suggests relativistic expansion in these sources. Normal CIV emission in two of the sources with an overpredicted Compton component suggests that although they, like BL Lac objects, have highly relativistic material apparently moving at small angle to the line of sight, they have a smaller fraction of the continuum component in the beam.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 284; 491-496
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  • 92
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    GASP cloud encounter statistics - Implications for laminar flow control flight (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The cloud observation archive from the NASA Global Atmospheric Sampling Program (GASP) is analyzed in order to derive the probability of cloud encounter at altitudes normally flown by commercial airliners, for application to a determination of the feasability of Laminar Flow Control (LFC) on long-range routes. The probability of cloud encounter is found to vary significantly with season. Several meteorological circulation features are apparent in the latitudinal distribution of cloud cover. The cloud encounter data are shown to be consistent with the classical midlatitude cyclone model with more clouds encountered in highs than in lows. Aircraft measurements of route-averaged time-in-clouds fit a gamma probability distribution model which is applied to estimate the probability of extended cloud encounter, and the associated loss of LFC effectiveness along seven high-density routes. The probability is demonstrated to be low.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Aircraft (ISSN 0021-8669); 21; 851-857
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  • 93
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    Some properties of the filamentary nebula at 1723 - 46 (1984)
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    Publication Date: 2011-08-19
    Description: High resolution spectra of the interstellar NaI D2 absorption line have been obtained for seven B-type stars aligned with an extensive filamentary nebula. Very fine filaments have now been found on a high contrast print of a deep H-alpha and forbidden N II plate, making identification as a fossilized remnant probable but uncertain. The inferred age is about 20,000 yr, the distance less than 200 pc, the diameter less than 17.5 pec, but the initial energy is only about 2 x 10 to the 47th erg.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 210; 693-699
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  • 94
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    Vertical temperature sounding of the atmosphere (1984)
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    Publication Date: 2011-08-19
    Description: Attention is given to physical principles that affect the determination of atmospheric temperature profiles from observations of outgoing IR and microwave radiation. Simultaneous analysis of IR and microwave observations enhances observations in each spectral region. While IR soundings have higher sensitivity to lower tropospheric temperatures, ground temperatures, and sea surface temperatures, microwave observations are not only more suited to stratospheric sounding but are sensitive to snow and ice cover. They significantly aid correction of IR observations for cloud effects. Because effective cloud parameters and snow and ice cover can be inferred from the observations, 'temperature sounders' also yield data for a number of important climatic parameters.
    Keywords: METEOROLOGY AND CLIMATOLOGY
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  • 95
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    Laser-induced fluorescence of green plants. I - A technique for the remote detection of plant stress and species differentiation (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The laser-induced fluorescence (LIF) of green plants was evaluated as a means of remotely detecting plant stress and determining plant type. Corn and soybeans were used as representatives of monocots and dicots, respectively, in these studies. The fluorescence spectra of several plant pigments was excited with a nitrogen laser emitting at 337 nm. Intact leaves from corn and soybeans also fluoresced using the nitrogen laser. The two plant species exhibited fluorescence spectra which had three maxima in common at 440, 690, and 740 nm. However, the relative intensities of these maxima were distinctly different for the two species. Soybeans had an additional slight maxima at 525 nm. Potassium deficiency in corn caused an increase in fluorescence at 690 and 740 nm. Simulated water stress in soybeans resulted in increased fluorescence at 440, 525, 690, and 740 nm. The inhibition of photosynthesis in soybeans by 3-(3-4-dichlorophenyl)-1-1-dimethyl urea (DCMU) gave incresed fluorescence primarily at 690 and 740 nm. Chlorosis as occurring in senescent soybean leaves caused a decrease in fluorescence at 690 and 740 nm. These studies indicate that LIF measurements of plants offer the potential for remotely detecting certain types of stress condition and also for differentiating plant species.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 23; 134-142
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  • 96
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    The radar cross section of dielectric disks (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A solution is presented for the backscatter (monostatic) radar cross section of dielectric disks of arbitrary shape, thickness, and dielectric constant. The result is obtained by employing a Kirchhoff-type approximation to obtain the fields inside the disk. The internal fields induce polarization and conduction currents from which the scattered fields and the radar cross section can be computed. The solution for the radar cross section obtained in this manner will be shown to agree with known results in the special cases of normal incidence, thin disks, and perfect conductivity. It will also be shown that the solution can be written as a product of the reflection coefficient of an identically oriented slab times the physical optics solution for the backscatter cross section of a perfectly conducting disk of the same shape. This result follows directly from the Kirchhoff-type approximation without additional assumptions.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Antennas and Propagation (ISSN 0018-926X); AP-32; 6-12
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  • 97
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    Grain destruction in interstellar shocks (1984)
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    Publication Date: 2011-08-18
    Description: The destruction of interstellar grains by nonthermal sputtering, thermal sputtering, and grain-grain collisions is discussed. It is concluded that large grains are easily destroyed by shocks in the interstellar medium, but that small grains are much more persistent. Since the MRN model has many more small grains than large ones, this means that the total number of grains is not significantly reduced even when half or more of the grain material is returned to the gas phase. Thus, the small grains are always available as condensation cores for mantle formation or redepletion of refractory grain materials.
    Keywords: ASTROPHYSICS
    Type: Royal Observatory Lab. and Observational Infrared Spectra of Interstellar Dust; p 26-32
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  • 98
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    Role of soil moisture in maintaining droughts (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The influence of soil moisture on the persistence of an ongoing drought was investigated. The case study of drought of the summer of 1980 was selected. The difference in the simulation of two identical twin runs: one with the climatological normal soil moisture and the other with anomalous soil moisture for drought conditions, were examined on the mean monthly circulation. It is found that a reduction in soil moisture did produce a corresponding reduction in precipitation. The pattern of the rainfall anomaly however, was not identical to the soil moisture (evapotranspiration) anomaly but had a good resemblance with observations.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Res. Rev., 1983; p 335-340
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  • 99
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    The sensitivity of a general circulation model to Saharan dust heating (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: During the Northern summer, sporadic outbreaks of wind borne Saharan dust are carried out over the Atlantic by the tropical easterlies. Optical depths due to the dust can reach 3 near the African coast, and the dust cloud can be detected as far west as the Caribbean Sea (Carlson, 1979). In order to obtain insight into the possible effects of Saharan dust on the weather and climate of North Africa and the tropical Atlantic Ocean, simulation experiments have been performed with the Climate Model of the Goddard Laboratory for Atmospheric Sciences. The most recent version of the model is described by Randall (1982). The model produces realistic simulations of many aspects of the observed climate and its seasonal variation.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Res. Rev., 1983; p 3323-328
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  • 100
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    Climate sensitivity with a seasonal cycle energy balance model (1984)
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    Publication Date: 2011-08-18
    Description: The sensitivity of climate which may have a local maximum as the ice cap passes through a midlatitude region where the atmosphere's transport efficiency varies strongly with latitude is examined. This behavior, found in a two level primitive equations climate model forced with annual mean insolation, was reproduced in an energy balance model (EBM) by making the diffusion coefficient a function of latitude. The two level seasonally varying EBM was applied and the global mean surface temperature vs. solar constant for this model are shown and two regions of enhanced sensitivity appear. The snowcover distributions around the year for three cases are shown.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Res. Rev., 1983; p 227-230
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