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  • EARTH RESOURCES AND REMOTE SENSING  (3,802)
  • AERODYNAMICS  (3,347)
  • ASTRONOMY
  • 1980-1984  (7,101)
  • 1970-1974  (1,878)
Collection
Keywords
Years
Year
  • 1
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    Radar-visible wind streaks in the Altiplano of Bolivia (1984)
    In:  CASI
    Details
    Publication Date: 2006-04-06
    Description: Isolated knobs that are erosional remnants of central volcanoes or of folded rocks occur in several areas of the Altiplano are visible on both optical and images. The optically visible streaks occur in the immediate lee of the knobs, whereas the radar visible streaks occur in the zone downwind between the knobs. Aerial reconnaissance and field studies showed that the optically visible streaks consist of a series of small ( 100 m wide) barchan and barchanoid dunes, intradune sand sheets, and sand hummocks (large shrub coppice dunes) up to 15 m across and 5 m high. On LANDSAT images these features are poorly resolved but combine to form a bright streak. On the radar image, this area also appears brighter than the zone of the radar dark streak; evidently, the dunes and hummocks serve as radar reflectors. The radar dark streak consists of a relatively flat, smooth sand sheet which lacks organized aerolian bedforms, other than occasional ripples. Wind velocity profiles show a greater U value in the optically bright streak zone than in the radar dark streak.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: NASA. Washington Rept. of Planetary Geology Program, 1983; p 271-272
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  • 2
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    The erosion of streamlined islands, longitudinal grooves and scour marks: Implications to the origin of the Martian outflow channels (1984)
    In:  CASI
    Details
    Publication Date: 2006-04-06
    Description: The diversity of proposed origins for large Martian outflow channels results from the differing interpretations given to the landforms associated with the outflow channels. In an attempt to help limit the possible mechanisms of channel erosion, detailed studies of three of the channel features were done; the streamlined islands, longitudinal grooves and scour marks. This examination involved a comparison of the martian streamlined islands with various streamlined landforms on Earth including those found in the Channel Scabland in large rivers, glacial drumlins, and desert yardangs. The comparisons included statistical analyses of the landform lengths versus widths and positions of maximum width, and an examination of the degree of shape agreement with the geometric lemniscate which was in turn demonstrated to correspond closely with true airfoil shapes. The analyses showed that the shapes of the martian islands correspond closely to the streamlined islands in rivers and the Channel Scabland land. Drumlins show a much smaller correlation. Erosional rock islands formed by glaciers are very much different in shape.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: NASA. Washington Rept. of Planetary Geol. Programs; p 200-202
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  • 3
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    The PDS-VAX intelligent plate scanning system of Trieste Astronomical Observatory (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: An intelligent subsystem for interfacing a PDS1010A digital microdensitometer to a DEC DR11W DMA 16 bit UNIBUS port in DEC VAX VMS environment was tested. The subsystem employs two MOTOROLA M68000 microprocessors with 128 KB data memory. The PDS primitives and the user defined high level scanning functions and preprocessing modules are loaded from the host computer into two 8 KB RAM memories in the microprocessors using a dedicated PDS control language. The subsystem is planned to employ a nonstandard photomultiplier electronics. Two design schemes were tested: (1) based on three amplifiers of gain 10 cascaded and multiplexed to a 12 bit AD converter, and (2) based on a single amplifier of gain 100 and two 14 bit AD converters.
    Keywords: ASTRONOMY
    Type: NASA. Goddard Space Flight Center Astron. Microdensitometry Conf.; p 175-187
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  • 4
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    Status of advanced airfoil tests in the Langley 0.3-meter transonic cryogenic tunnel (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A joint NASA/U.S. industry program to test advanced technology airfoils in the Langley 0.3-meter Transonic Tunnel (TCT) was formulated under the Langley ACEE Project Office. The objectives include providing U.S. industry an opportunity to compare their most advanced airfoils to the latest NASA designs by means of high Reynolds number tests in the same facility. At the same time, industry would again experience in the design and construction of cryogenic test techniques. The status and details of the test program are presented. Typical aerodynamic results obtained, to date, are presented at chord Reynolds number up to 45 x 10(6) and are compared to results from other facilities and theory. Details of a joint agreement between NASA and the Deutsche Forschungs- und Versuchsantalt fur Luft- and Raumfahrt e.V. (DFVLR) for tests of two airfoils are also included. Results of these tests will be made available as soon as practical.
    Keywords: AERODYNAMICS
    Type: Advan. Aerodyn.: Selected NASA Res.; p 37-53
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  • 5
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    Component testing for dynamic model verification (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Dynamic model verification is the process whereby an analytical model of a dynamic system is compared with experimental data, adjusted if necessary to bring it into agreement with the data, and then qualified for future use in predicting system response in a different dynamic environment. These are various ways to conduct model verification. The approach taken here employs Bayesian statistical parameter estimation. Unlike curve fitting, whose objective is to minimize the difference between some analytical function and a given quantity of test data (or curve), Bayesian estimation attempts also to minimize the difference between the parameter values of that funciton (the model) and their initial estimates, in a least squares sense. The objectives of dynamic model verification, therefore, are to produce a model which: (1) is in agreement with test data; (2) will assist in the interpretation of test data; (3) can be used to help verify a design; (4) will reliably predict performance; and (5) in the case of space structures, will facilitate dynamic control.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 2; 15 p
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  • 6
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    Post and a random-walk search mode (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Multidisciplinary analysis often requires optimization of nonlinear systems that are subject to constraints. Trajectory optimization is one example of this situation. The Program to Optimize Simulated Trajectories (POST) was used successfully for a number of problems. The purpose is to describe POST and a new optimization approach that has been incorporated into it. Typical uses of POST will also be illustrated. The projected-gradient approach to optimization is the preferred option in POST and is discussed. A new approach to optimization, the random-walk approach, is described, and results with the random-walk approach are presented.
    Keywords: AERODYNAMICS
    Type: Recent Experiences in Multidisciplinary Analysis and Optimization, Part 2; 23 p
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  • 7
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    Wall interference measurements for three-dimensional models in transonic wind tunnels: Experimental difficulties (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The purpose is not to provide a detailed discussion of several wall interference experiments, but rather to use these experiments (recently accomplished in the Boeing Transonic Wind Tunnel (BTWT) to illustrate the problems associated with many of the measurements required by current wall interference assessment/correction (WIAC) procedures. The wall correction to lift is emphasized. It is shown that, because conventional tunnels and relatively small models continue to be used, the flow field or flow boundary measurements to be made impose severe requirements on the experiment itself. In some cases, existing instrumentation and test techniques may not be adequate to obtain the data accuracies needed.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 21-42
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  • 8
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    Adaptation of a four-wall interference assessment/correction procedure for airfoil tests in the 0.3-m TCT (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Based upon limited, initial observations of wall interference corrections obtained for one airfoil test, there is a need for assessing the upstream flow direction. If there is no direct measurement then a two-pass correction procedure similar to the one described here is required. Questions have arisen pertaining to the correct interpretation of the pressure coefficients measured on the slats of a slotted tunnel wall, the interpretation of just what the calculated equivalent body encompasses or should include, and what can or should be considered as quantitative criteria for data correctability. Further studies using this modified procedure will address these questions. Hopefully, a meaningful WIAC procedure can be validated for the airfoil tests in the 0.3-m TCT.
    Keywords: AERODYNAMICS
    Type: Wind Tunnel Wall Interference Assessment and Correction, 1983; p 393-414
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  • 9
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    Some experience with Barnwell-Sewall type correction to two-dimensional airfoil data (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A series of airfoils were tested in the Langley 0.3-Meter Transonic Cryogenic Tunnel (TCT) at Reynolds numbers from 2 to 50 million. The 0.3-m TCT is equipped with Barnwell slots designed to minimize blockage due to the tunnel flow and ceiling. This design suggests that sidewall corrections for blockage is needed, and that a lifting airfoil produces a change in angle of attack. Sidewall correction methods were developed for subsonic and subsonic-transonic flow. Comparisons of theory with experimental data obtained in the 0.3-m TCT for two airfoils, the British NPL 9510 and the German R-4 are presented. The NPL 9510 was tested as part of the NASA/United Kingdom Joint Aeronautical Program and R-4 was tested as part f the DFVLR/NASA Advanced Airfoil Research Program. For the NPL 9510 airfoil, only those test points that one would anticipate being difficult to predict theoretically are presented.
    Keywords: AERODYNAMICS
    Type: Wind Tunnel Wall Interference Assessment and Correction, 1983; p 375-392
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  • 10
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    Experiences with a high-blockage model tested in the NASA Ames 12-foot pressure wind tunnel (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Representation of the flow around full-scale ships was sought in the subsonic wind tunnels in order to a Hain Reynolds numbers as high as possible. As part of the quest to attain the largest possible Reynolds number, large models with high blockage are used which result in significant wall interference effects. Some experiences with such a high blockage model tested in the NASA Ames 12-foot pressure wind tunnel are summarized. The main results of the experiment relating to wind tunnel wall interference effects are also presented.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 345-360
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  • 11
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    An inerference assessment approach for a three-dimensional slotted tunnel with sparse wall pressure data (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The various procedures referred to as wall interference assessment and correction procedures presume the existence of a surface distribution of data (usually static pressure) measured over a surface on or near the tunnel walls for each test point to be assessed. An alternative approach in which a reasonably sophisticated computer model of the test section flow would be fitted parametrically to a sparse set of measured data is presented. The measurements provides line distributions of static pressure near the center lines of the top, side and bottom walls. The development of a test section model incorporating explicit recognition of discrete slots of finite length with controlled flow reentry into the solid wall downstream portion of the tunnel is shown.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center. Wind Tunnel Wall Interference Assessment and Correction, 1983; p 323-334
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  • 12
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    Multiprocess evolution of landforms in the Kharga Region, Egypt: Applications to Mars (1984)
    In:  CASI
    Details
    Publication Date: 2006-04-06
    Description: In order to understand better the polygenetic evolution of landforms on the martian surface, field studies were conducted in and around the Kharga Depression, Egypt. The Kharga region, on the eastern edge of Egypt's Western Desert, was subject to erosion under mostly hyperarid climatic conditions, punctuated by brief pluvial episodes of lesser aridity, since early Pleistocene time. The region contains numerous landforms analogous to features on the martian surface: yardangs carved in layered surficial deposits and in bedrock, invasive dune trains, wind-modified channels and interfluves, and depressions bounded by steep scarps. Like many of the topographic depresions on Mars, the Kharga Depression was invaded by crescentic dunes. In Egypt, stratigraphic relations between dunes, yardangs, mass-wasting debris, and wind-eroded flash-flood deposits record shifts in the relative effectiveness of wind, water, and mass-wasting processes as a function of climate change.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: NASA. Washington Rept. of Planetary Geology Program, 1983; p 225-227
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  • 13
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    Interference from slotted walls (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Wall interference is made predominant in tunnel models and by wall geometries to facilitate the study of slot flow. The viscous effects in slots are studied by two dimensional measurements of flow. Wall interference is assessed by measuring pressure distributions at two levels near the walls. Interference on lifting delta wings is calculated. Pressure distributions at inner boundaries show basis axisymetries between the pressure side and the suction side, pointing to the necessity of having wider slots on the pressure side.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 293-300
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  • 14
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    Development in UK of a method for calculating tunnel wall corrections from flow measurements (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Classical methods for calculation of wall corrections which are not satisfactory for a number of flows of interest are discussed. To meet these objections, a number of methods were developed which use measurements of the low at or close to the tunnel walls as an outer boundary condition to define wall interference. The development, assessment and application of one such method is summarized.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 259-271
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  • 15
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    NLR activities in the field of wind tunnel wall interference (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Measured field data as a boundary condition for calculating the interference flow field were applied. They are divided into two categories. In the first category, the field data must consist of distributions of a single velocity component, and an accurate estimate of the hypothetical free air contribution of the model to this component is required. The differences between measured values and estimated model contributions are attributed to wall interference and they establish the boundary condition. The associated field data measurements are simple, yet the necessary model representation generally is a serious drawback. The second category requires field data which consist of velocity vector distributions at the price of multicomponent measurements, but at the profit that no information at all is required about the model. In solid wall test sections, the price is reduced to virtually zero but the profit remains.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 221-229
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  • 16
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    Performance of two transonic airfoil wind tunnels utilizing limited ventilation (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A limited-zone ventilated wall panel was developed for a closed-wall icing tunnel which permitted correct simulation of transonic flow over model rotor airfoil sections with and without ice accretions. Candidate porous panels were tested in the Ohio State University 6- x 12-inch transonic airfoil tunnel and result in essentially interference-free flow, as evidenced by pressure distributions over a NACA 0012 airfoil for Mach numbers up to 0.75. Application to the NRC 12- x 12-inch icing tunnel showed a similar result, which allowed proper transonic flow simulation in that tunnel over its full speed range.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 165-170
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  • 17
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    Investigations of flow field perturbations induced on slotted transonic-tunnel walls (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The free-stream interference caused by the flow through the slotted walls of the test sections of transonic wind tunnels has continuously a problem in transonic tunnel testing. The adaptive-wall transonic tunnel is designed to actively control the near-wall boundary conditions by sucking or blowing through the wall. In order to make the adaptive-wall concept work, parameters for computational boundary conditions must be known. These parameters must be measured with sufficient accuracy to allow numerical convergence of the flow field computations and must be measured in an inviscid region away from the model that is placed inside the wind tunnel. The near-wall flow field was mapped in detail using a five-port cone probe that was traversed in a plane transverse to the free-stream flow. The initial experiments were made using a single slot and recent measurements used multiple slots, all with the tunnel empty. The projection of the flow field velocity vectors on the transverse plane revealed the presence of a vortex-like flow with vorticity in the free stream. The current research involves the measurement of the flow field above a multislotted system with segmented plenums behind it, in which the flow is controlled through several plenums simultaneously. This system would be used to control a three-dimensional flow field.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 119-142
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  • 18
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    Assessment of lift- and blockage-induced wall interference in a three-dimensional adaptive-wall tunnel (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A three-dimensional adaptive-wall wind tunnel experiment was conducted at Ames Research Center. This experiment demonstrated the effects of wall interference on the upwash distribution on an imaginary surface surrounding a lifting wing. This presentation demonstrates how the interference assessment procedure used in the adaptive-wall experiments to determine the wall adjustments can be used to separately assess lift- and blockage-induced wall interference in a passive-wall wind tunnel. The effects of lift interference on the upwash distribution and on the model lift coefficient are interpreted by a simple horseshoe vortex analysis.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 89-100
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  • 19
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    Wind tunnel wall interference in closed, ventilated and adaptive test sections (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A wall interference correction method for closed rectangular test sections was developed which uses measured wall pressures. Measurements with circular discs for blockage and a rectangular wing as a lift generator in a square closed test section validate this method. These measurements are intended to be a basis of comparison for measurements in the same tunnel using ventilated (in these case, slotted) walls. Using the vortex lattice method and homogeneous boundary conditions, calculations were performed which show sufficiently high pressure levels at the walls for correction purposes in test sections with porous walls. In Gottingen, an adaptive test section (which is a deformable rubber tube of 800 mm diameter) was built and a computer program was developed which is able to find the necessary wall adaptation for interference-free measurements in a single step. To check the program prior to the first run, the vortex lattice method was used to calculate wall pressure distributions in the nonadapted test section as input data for the one-step method. Comparison of the pressure distribution in the adapted test section with free-flight data shows nearly perfect agreement. An extension of the computer program can be made to evaluate the remaining interference corrections.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 61-78
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  • 20
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    Review of the advanced technology airfoil test program in the 0.3-meter transonic cryogenic tunnel (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The following areas were addressed: interchangeable test sections in the 0.3-M Transonic Cryogenic Tunnel (TCT); typical airfoil installation; airfoil capability; advanced technology airfoil test (ATAT); effects of the Reynolds number on the normal force coefficient; effects of the Reynolds number on the drag coefficient; and comparison of experimental results with theory.
    Keywords: AERODYNAMICS
    Type: Wind Tunnel Wall Interference Assessment and Correction, 1983; p 361-374
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  • 21
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    Determination of equivalent model geometry for tunnel wall interference assessment/correction (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A formula for the determination of equivalent model geometry with two variables measured at the interface is derived, based on two dimensional subsonic flow. This predicted model profile is a reasonable initial estimate for transonic flow as long as the sonic region does not reach the interface. A general formula is given in two forms. One is in terms of complex variable functions and the other is an integral equation. The complex-function formula has the advantage of using analytic expressions. The integral equation form requires a numerical solution after assuming the model geometry as a polynomial function. Examples are given to illustrate the application of the formulas.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 335-342
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  • 22
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    Experiments examining the shapes of isolated bars in comparison with those occurring in braided rivers (1984)
    In:  CASI
    Details
    Publication Date: 2006-04-06
    Description: Sand bars and islands within braided rivers have characteristic rhomboid or diamond shapes, often becoming very complex in form as the density of islands increases. Similar forms are observed in the martian outflow channels where the islands occur in groups. This contrasts with the more isolated martian islands which have airfoil shapes, as do isolated streamlined islands in rivers and in the Channeled Scabland. These observations indicate that the bar and island forms are controlled by the density of the islands, with increasing island interaction and flow modification as the density increases. As a continuation of previous flume experiments on the shapes of isolated islands, a new series of experiments investigate the modifications produced by a progressive increase in island density, finally leading to a true braided system.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: NASA. Washington Rept. of Planetary Geol. Programs; p 198-199
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  • 23
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    STEP flight experiments Large Deployable Reflector (LDR) telescope (1984)
    In:  CASI
    Details
    Publication Date: 2006-04-03
    Description: Flight testing plans for a large deployable infrared reflector telescope to be tested on a space platform are discussed. Subsystem parts, subassemblies, and whole assemblies are discussed. Assurance of operational deployability, rigidization, alignment, and serviceability will be sought.
    Keywords: ASTRONOMY
    Type: NASA. Langley Research Center STEP Expt. Requirements; p 257-278
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  • 24
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    Wind tunnel wall interference correction for aircraft models (1984)
    In:  CASI
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    Publication Date: 2006-02-14
    Description: Wall interference correction procedures seek to determine the required changes in certain flow or geometric parameters so that the difference between the flow properties at the model's surface in the tunnel and free air are minimized. A transonic and a linear correction procedure were developed for aircraft models. In addition to Mach number and angle of attack corrections, an estimate of the accuracy of the corrections is provided by the transonic correction procedure. Lift, pitching moment and pressure measurements near the tunnel walls are required. The efficiency and accuracy of the correction procedure are improved. Moreover, correction of both the wing and tail angles of attack is allowed. The procedure is valid for transonic as well as subcritical flows. However, for subcritical flows further approximations and simplifying assumptions are made, leading to a very simple and efficient correction procedure.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center. Wind Tunnel Wall Interference Assessment and Correction, 1983; p 301-322
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  • 25
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    Tunnel constraint for a jet in crossflow (1984)
    In:  CASI
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    Publication Date: 2006-02-14
    Description: A facet of a unified tunnel correction scheme which uses wall pressures to determine tunnel induced blockage and upwash is described. With this method, there is usually no need to use data concerning model forces or power settings to find the interference; it follows directly from the pressures and tunnel dimensions. However, highly inclined jets do not produce good pressure signatures and are highly three dimensional, so they must be treated differently. Flow modeling is also discussed.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center. Wind Tunnel Wall Interference Assessment and Correction, 1983; p 273-290
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  • 26
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    Progress in wind tunnel wall interference assessment/correction procedures at the NAE (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Wall corrections as a function of wall porosity in the transonic wall interference problem was assessed. Effective porosities primarily for the two dimensional case were established as follows: (1) comparison of experimental data for two geometrically similar models of different chord/height ratio, an overall value of wall porosity could be deduced; (2) theoretical development which allows for unequal porosity for the floor and ceiling and wall boundary pressure measurements, porosities for floor and ceiling could be deduced; (3) a scheme was developed which allowed unequal porosity of floor and ceiling and streamwise varying porosity. The boundary layer development along the perforated floor and ceiling under the influence of the model pressure field, variations in boundary layer thickness underlining the difficulties in deducing meaningful values of wall porosity were determined. Wall boundary pressure measurement, in combination with singularity modelling of the airfoil, was sufficient to yield required information on the wall interference flow without having to establish some value for wall porosity. The singularity modelling of the airfoil initially covered only lift and volume but was extended to include drag and pitching moment, and second order volume term. It is shown by asymptotic transonic small disturbance analysis, that the derived corrections to angle of attack and free stream Mach number are correct to the first order.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 231-257
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  • 27
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    Asymptotic methods for wind tunnel wall corrections at transonic speed (1984)
    In:  CASI
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    Publication Date: 2006-02-14
    Description: The effort to develop classical methods to compute wall interference at transonic speeds is outlined. The two-dimensional theory and three-dimensional development are discussed. Also, some numerical application of the two-dimensional work are indicated. The basic advantages of the asymptotic theory are noted.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 193-203
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  • 28
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    Effect of boundary layers on solid walls in three-dimensional subsonic wind tunnels (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A solution for the tunnel wall boundary layer effects for three-dimensional subsonic tunnels is presented. The model potentials are represented with simple singularities placed on the centerline of the tunnel and Laplace's equation in cylindrical coordinates is solved for either the conventional homogeneous slotted-wall boundary condition, the solid-wall viscous boundary condition, or a combination of them. The most pronounced wall boundary layer effect is on solid blockage for completely closed wind tunnels. Boundary layers on the wall reduce the blockage from the solid-wall, no-boundary-layer case in a manner similar to opening slots in a solid wall. Additionally, for solid-wall tunnel configurations, the streamline curvature interference factor is reduced by a significant amount, whereas the lift interference factor at the model station does not depend on the boundary layer parameter. For combination wall configurations, the slot effect of the horizontal walls dominates the viscous effect of the solid sidewalls.
    Keywords: AERODYNAMICS
    Type: Wind Tunnel Wall Interference Assessment and Correction, 1983; p 205-218
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    Experiments suitable for wind tunnel wall interference assessment/correction (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Three experiments suitable for wall interference assessment and evaluation of proposed correction methods are presented. The experiments are: (1) a series of airfoil tests using a newly designed transonic flow facility that employs side-wall boundary layer suction and upper- and lower-wall shaping; (2) tests on a swept airfoil section spanning a solid-wall wind tunnel with fixed contouring on all four walls; and (3) tests on a swept wing of aspect ratio 3 mounted in a solid-wall wind tunnel with fixed flat walls. Each of the experiments provides data on the airfoil sections as well as on the wind tunnel walls. All the experiments were performed in solid wall wind tunnels corrected for boundary layer displacement effects. Although the experiments were performed primarily to evaluate computer code performance, it is believed that they also provide information that can be used to evaluate methods for assessing and correcting wall interference effects.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 171-190
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    Effect of upstream sidewall boundary layer removal on an airfoil test (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Sidewall boundary layer effects were investigated by applying partial upstream sidewall boundary layer removal in the Langley 0.3-m transonic cryogenic tunnel. Over the range of sidewall boundary layer displacement thickness of these tests the influence on pressure distribution was found to be small for subcritical conditions; however, for supercritical conditions the shock position was affected by the sidewall boundary layer. For these tests (with and without boundary layer remove) comparisons with predictions of the GRUMFOIL computer code indicated that Mach number corrections due to the sidewall boundary layer improve the agreement for both subcritical and supercritical conditions. The results also show that sidewall boundary layer removal reduces the magnitude of the sidewall correction; however, a suitable correction must still be made.
    Keywords: AERODYNAMICS
    Type: Wind Tunnel Wall Interference Assessment and Correction, 1983; p 143-163
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    A data base for three-dimensional all-interference code evaluation (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A validation of a measured boundary condition technique was carried out to demonstrate the feasibility of a wall interference assessment/correction (WIAC) system. An experimental evaluation was also carried out to compare performances of various techniques, to define the number of necessary boundary measurements for accurate assessment/corrections and to define the envelope of test conditions for which accurate assessment/corrections are achieved. The relative merits of a WIAC system and an adaptive wall tunnel are compared. The measurement surface boundary data is performed with a system of two rotating pipes. These pipes sweep out a cylindrical measurement surface near the tunnel walls, approximately one inch from the wall at the closest point. The experimental model was specially designed and fabricated for the adaptive wall experiments. The model is a wing/tail/body configuration with swept lifting surface. The boundary data taken in Tunnel 1T with the rotating pipe system has been shown to offer several attractive features for WIAC code evaluation. Good spatial resolution of measurements is achieved and measurements are made upstream and downstream of the model. Also, two velocity components are determined.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 101-118
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    Survey of ONERA activities on adaptive-wall applications and computation of residual corrections (1984)
    In:  CASI
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    Publication Date: 2006-02-14
    Description: The research undertaken concerning the computation and/or reduction of wall interference follows two main axes: improvement of wall correction determinations, and use of adaptive flexible walls. The use of wall-measured data to compute interference effects is reliable when the model representation is assessed by signatures with known boundary conditions. When the computed interferences are not easily applicable to correcting the results (especially for gradients in two-dimensional cases), the flexible adaptive walls in operation in T2 are an efficient and assessed means of reducing the boundary effects to a negligible level, if the direction and speed of the flow are accurately measured on the boundary. The extension of the use of adaptive walls to three-dimensional cases may be attempted since the residual corrections are assumed to be small and are computable.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 43-60
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    Characteristics of the SIR-A system and images (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Sample images obtained with the Shuttle Imaging Radar A (SIR-A) are presented, along with design and performance features of the SIR-A, Seasat and Landsat images of the same scenes for comparison purposes. The SIR-A functions at the L-band 25 cm at a frequency of 1278 GHz with a spectral bandwidth of 6 MHz. The images were taken at an angle of 47 deg and furnished a resolution of 40 m from an altitude of 259 km. The images covered a ground swath 50 km wide. The images are provided to assist in the development of effective techniques for interpreting radar imagery. The SIR-A instrument is a precursor of another imaging device which will be flown around Venus. The images provided include sections of France, Sardinia and Algeria.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Photo Interpretation (ISSN 0031-8523); 23; 4-17
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    Viscous transonic flow computation over Space Shuttle configuration (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A thin-layer Navier-Stokes code capable of predicting steady-state viscous flows is applied to the transonic flow over a Space Shuttle configuration. The code is written in the generalized coordinate system, and the grid-generation code of Fujii (1983) is used for the discretization of the flow field. The flow-field computation is done using the CRAY 1S computer at NASA Ames. The computed result is physically reasonable, even though no experimental data is available for the comparison purpose.
    Keywords: AERODYNAMICS
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    Infrared mapping of galaxian centers: Star forming regions with kiloparsec scale sizes (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A 1 to 20 micron mapping of the centers of galaxies encompassing the regions that extend out to several kiloparsecs from the nuclei is reviewed. Power emerging at or = 5 microns is a direct measure of the number of young stars present. This conclusion is strongly supported by the large-scale association of the infrared-emitting regions with visual continuum and line emission indicative of young stars, and by the similarity of the energy distributions to those of Galactic HII region/molecular cloud complexes. Much of the young-star activity is completely hidden from view. At shorter wavelengths, a variety of processes, including bremsstrahlung, are evident.
    Keywords: ASTRONOMY
    Type: Royal Observatory Star Formation Workshop; p 183-198
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  • 36
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    Analysis of Landsat-4 Thematic Mapper data for classification of forest stands in Baldwin County, Alabama (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A computer-implemented classification has been derived from Landsat-4 Thematic Mapper data acquired over Baldwin County, Alabama on January 15, 1983. One set of spectral signatures was developed from the data by utilizing a 3x3 pixel sliding window approach. An analysis of the classification produced from this technique identified forested areas. Additional information regarding only the forested areas. Additional information regarding only the forested areas was extracted by employing a pixel-by-pixel signature development program which derived spectral statistics only for pixels within the forested land covers. The spectral statistics from both approaches were integrated and the data classified. This classification was evaluated by comparing the spectral classes produced from the data against corresponding ground verification polygons. This iterative data analysis technique resulted in an overall classification accuracy of 88.4 percent correct for slash pine, young pine, loblolly pine, natural pine, and mixed hardwood-pine. An accuracy assessment matrix has been produced for the classification.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 37
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    Satellite land remote sensing advancements for the eighties; Proceedings of the Eighth Pecora Symposium, Sioux Falls, SD, October 4-7, 1983 (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Among the topics discussed are NASA's land remote sensing plans for the 1980s, the evolution of Landsat 4 and the performance of its sensors, the Landsat 4 thematic mapper image processing system radiometric and geometric characteristics, data quality, image data radiometric analysis and spectral/stratigraphic analysis, and thematic mapper agricultural, forest resource and geological applications. Also covered are geologic applications of side-looking airborne radar, digital image processing, the large format camera, the RADARSAT program, the SPOT 1 system's program status, distribution plans, and simulation program, Space Shuttle multispectral linear array studies of the optical and biological properties of terrestrial land cover, orbital surveys of solar-stimulated luminescence, the Space Shuttle imaging radar research facility, and Space Shuttle-based polar ice sounding altimetry.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 38
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    Nonlinear aerodynamic effects on bodies in supersonic flow (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 21; 809-815
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    Offshore oil in the Alaskan Arctic (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Oil and gas deposits in the Alaskan Arctic are estimated to contain up to 40 percent of the remaining undiscovered crude oil and oil-equivalent natural gas within U.S. jurisdiction. Most (65 to 70 percent) of these estimated reserves are believed to occuur offshore beneath the shallow, ice-covered seas of the Alaskan continental shelf. Offshore recovery operations for such areas are far from routine, with the primary problems associated with the presence of ice. Some problems that must be resolved if efficient, cost-effective, environmentally safe, year-round offshore production is to be achieved include the accurate estimation of ice forces on offshore structures, the proper placement of pipelines beneath ice-produced gouges in the sea floor, and the cleanup of oil spills in pack ice areas.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Science (ISSN 0036-8075); 225; 371-378
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  • 40
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    The Gamma-Ray Observatory mission objectives and its significance for gamma-ray astronomy (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The Gamma Ray Observatory (GRO) is an approved NASA mission, programmed for launch in 1988. Its complement of four detectors has established goals: (1) to study the nature of compact gamma-ray sources such as neutron stars and black holes, or objects whose nature is yet to be understood; (2) to search for evidence of nucleosynthesis especially in the regions of supernovae; (3) to study structural features and dynamical properties of the Galaxy; (4) to explore other galaxies, especially the extraordinary types such as radio, Seyferts, and quasars; and (5) to study cosmological effects by examining the diffuse radiation in detail. This paper discusses the design, objectives, and expected scientific results of each of the GRO instruments in view of the GRO mission goals.
    Keywords: ASTRONOMY
    Type: Advances in Space Research (ISSN 0273-1177); 3; 10-12
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  • 41
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    New implicit boundary procedures - Theory and applications (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Previously cited in issue 5, p. 579, Accession no. A83-16536
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 22; 1094-110
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  • 42
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    Numerical simulations of unsteady transonic flow in diffusers (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Previously cited in issue 15, p. 2346, Accession no. A82-31959
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 22; 1139-114
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  • 43
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    Effects of viscosity on transonic-aerodynamic and aeroelastic characteristics of oscillating airfoils (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 21; 700-707
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  • 44
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    Leeside flows over delta wings at supersonic speeds (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 21; 680-686
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  • 45
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    Calculations of radar backscattering coefficient of vegetation-covered soils (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The present investigation has the objective to develop a simple 'user's' model for simulating the measured radar backscattering coefficients from vegetation-covered fields in conjunction with the data obtained by Jackson et al. (1980, 1982). The theoretical work reported by Fung and Eom (1981) provides the basis for the model. Certain modifications are related to a consideration of the effect of a vegetation canopy. The first part of the model is concerned with a description of scatter from rough bare soil, while the second part takes into account the effect of a vegetation cover. It is shown that the measured angular distribution of the backscattering coefficient of vegetation-covered fields can be satisfactory reproduced by using the developed model.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Remote Sensing of Environment (ISSN 0034-4257); 15; 119-133
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  • 46
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    Atmospheric effect on classification of finite fields (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The atmospheric effect on the upward radiance of sunlight scattered from the earth-atmosphere system is strongly influenced by the contrasts between fields and their sizes. In this paper, the radiances above finite fields are computed to simulate radiances measured by a satellite. A simulation case including 11 agricultural fields and four natural fields (water, soil, savanah, and forest) is used to test the effect of field size, background reflectance, and optical thickness of the atmosphere on the classification accuracy. For a given atmospheric turbidity, the atmospheric effect on classification of surface features may be much stronger for nonuniform surfaces than for uniform surfaces. Therefore, the classification accuracy of agricultural fields and urban areas is dependent not only on the optical characteristics of the atmosphere, but also on the size of the surface elements to be classified and their contrasts. It is concluded that new atmospheric correction methods, which take into account the finite size of the fields, are needed.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Remote Sensing of Environment (ISSN 0034-4257); 15; 95-118
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  • 47
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    The S201 far-ultraviolet imaging survey. II - A field in Cygnus (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Far-ultraviolet imagery of a region in Cygnus, a 20 deg diameter field centered near (1950) R. A. 21 h 31.2 m decl. +37 deg 25 arcmin, was obtained by the S201 far-ultraviolet camera during the Apollo 16 mission. In a 10 minute exposure covering the 1250-1600 A wavelength range (effective wavelength 1400 A), 730 star images can be detected, corresponding to a limiting ultraviolet magnitude of about m (1400) = 10. Assuming nominal interstellar extinction values in this region near the galactic plane, this result corresponds to the detection of A0 V stars to a distance of 300 pc and of B0 V stars to 1500 pc. Uncertainties in spectral classification and interstellar extinction for individual objects are probably more significant than calibration or measurement errors. Most of the objects detected are identified with stars in the Smithsonian Astrophysical Observatory Star Catalog (1966), or the Catalog of Stellar Identifications (1979) or both, but 87 objects remain unidentified (or are identified with late-type stars).
    Keywords: ASTRONOMY
    Type: Astrophysical Journal Supplement Series (ISSN 0067-0049); 54; 271-290
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  • 48
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    Fresh attack on laminar flow (1984)
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    Publication Date: 2011-08-18
    Description: Laminar flow control is a technology with great potential for aircraft drag reduction. Stabilization of laminar boundary layers became known as natural laminar flow (NLF) and research led to the development of NLF airfoils. Research was also conducted on stabilization by suction, referred to as laminar flow control (LFC). Experiments demonstrated that extensive laminar flow could be achieved in flight. However, there remained doubts regarding the practicality of producing, with the technology then available, wing surfaces sufficiently smooth and wavefree to meet laminar-flow criteria and maintaining the wing surface quality in normal service. In 1976, the Aircraft Energy Efficiency (ACEE) program was begun by NASA to develop fuel-conservative technology for commercial transports. The progress of the ACEE program is discussed. Attention is given to LFC wing structures, and LFC leading-edge systems.
    Keywords: AERODYNAMICS
    Type: Aerospace America (ISSN 0740-722X); 22; 72-76
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    Space Shuttle heating analysis with variation in angle of attack and catalycity (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Previously cited in issue 5, p. 586, Accession no. A83-16747
    Keywords: AERODYNAMICS
    Type: Journal of Spacecraft and Rockets (ISSN 0022-4560); 21; 217-219
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  • 50
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    The influence of autocorrelation in signature extraction - An example from a geobotanical investigation of Cotter Basin, Montana (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The presence of positive serial correlation (autocorrelation) in remotely sensed data results in an underestimate of the variance-covariance matrix when calculated using contiguous pixels. This underestimate produces an inflation in F statistics. For a set of Thematic Mapper Simulator data (TMS), used to test the ability to discriminate a known geobotanical anomaly from its background, the inflation in F statistics related to serial correlation is between 7 and 70 times. This means that significance tests of means of the spectal bands initially appear to suggest that the anomalous site is very different in spectral reflectance and emittance from its background sites. However, this difference often disappears and is always dramatically reduced when compared to frequency distributions of test statistics produced by the comparison of simulated training sets possessing equal means, but which are composed of autocorrelated observations.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: International Journal of Remote Sensing (ISSN 0143-1161); 5; 315-332
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    Objective assessment of Advanced Very High Resolution Radiometer data for land cover mapping (1984)
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    Publication Date: 2011-08-18
    Description: The validity of using data from the Advanced Very High Resolution Radiometer (AVHRR) of the satellites NOAA-6 and NOAA-7 for land cover mapping is assessed by making comparisons with much higher resolution LANDSAT multi-spectral scanner (MSS) data. Near synchronous data for both systems are analysed for test sites in the Imperial Valley, California, the Nile Delta, and southern Italy. The results strongly indicate that despite the very coarse resolution of the AVHRR data compared with conventional MSS data they are sufficiently strongly correlated to suggest that the former have significant potential for land cover mapping, especially at small scales and for large areas. Hence the outstanding benefits of AVHRR data, namely their high temporal frequency, relative cheapness and low data volumes for image processing, may readily be taken advantage of for such tasks.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: International Journal of Remote Sensing (ISSN 0143-1161); 5; 497-504
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    Determining asteroid masses from perturbations on Mars (1984)
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    Publication Date: 2011-08-18
    Description: The orbit of Mars is perturbed more than 5 m, a value compatible with the accuracy of the Viking Lander ranging data, by about three dozen asteroids. In addition to larger asteroids throughout the belt, significant perturbations of long period are generated by smaller objects near commensurabilities with Mars. The largest periodic terms induced by 1 Ceres and 2 Pallas have amplitudes of 0.8 and 0.2 km, respectively, both with 10-year periods. Due to a near commensurability, 4 Vesta causes a 5-km, 52-year term. While the Viking ranges will yield significant mass determinations for the largest three asteroids, and some of the smaller bodies should be detectable, it will be difficult to separate the smaller bodies with useful accuracies. Accurate discrimination must await range data from future missions to Mars or other bodies in the neighborhood of the asteroid belt. The Viking ranges can also yield improved masses for the outer planets (except Pluto), an application which is being exploited by groups analyzing these data. Uncertainties in the asteroid masses limit the ultimate accuracy of the Viking determinations of both the long time scale motion of the system of the inner four planets with respect to an inertial frame and the rate of change of the gravitational constant.
    Keywords: ASTRONOMY
    Type: Icarus (ISSN 0019-1035); 57; 1-13
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    A search for the 10-micron silicate feature in periodic Comet Grigg-Skjellerup (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A 10-micron spectrum of periodic Comet Grigg-Skjellerup was obtained on 22 June 1982 with the UCL array spectrometer at the United Kingdom Infrared Telescope, Mauna Kea. No emission feature is obvious in the spectrum. The observed spectrum can be fit equally well by a model of small hot absorbing grains or by a composite model with less than or equal to 30 percent (3sigma) warm, 'dirty' silicate grains. The latter model is consistent with the silicate abundance in Comet Kohoutek, which did display an emission feature at 10 microns.
    Keywords: ASTRONOMY
    Type: Astronomical Journal (ISSN 0004-6256); 89; 170
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  • 54
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    Broad band X-ray astronomical spectroscopy (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The Broad Band X-Ray Telescope (BBXRT) experiment has been designed for high sensitivity, moderate resolution spectrophotometry of cosmic sources in the range 0.5 to 12 keV. Principal elements are two co-aligned imaging telescopes with cooled Si(Li) detectors at each focus. The mirror design uses an approximate geometry of tightly nested, conical, foil reflectors that allow a large filling factor (high throughput) at small grazing angles (high energy response). Each detector consists of a cluster of five elements defined with grooves on a single crystal. This arrangement affords some spatial resolution as well as a means of substantial background reduction. Shuttle borne measurements will typically be of 2000 s duration for sources with a flux of 10 to the -12 erg/sq cm-s.
    Keywords: ASTRONOMY
    Type: IEEE Transactions on Nuclear Science (ISSN 0018-9499); NS-31; 786-790
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    Thermal microwave emission from vegetated fields - A comparison between theory and experiment (1984)
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    Publication Date: 2011-08-18
    Description: The radiometric measurements over bare field and fields covered with grass, soybean, corn, and alfalfa were made with 1.4- and 5-GHz microwave radiometers during August-October 1978. The measured results are compared with radiative transfer theory treating the vegetated fields as a two-layer random medium. It is found that the presence of a vegetation cover generally gives a higher brightness temperature T sub B than that expected from a bare soil. The amount of this T sub B excess increases with increase in the vegetation biomass and in the frequency of the observed radiation. The results of radiative transfer calculations, which include a parameter characterizing ground surface roughness, generally match well with the experimental data.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: IEEE Transactions on Geoscience and Remote Sensing (ISSN 0196-2892); GE-22; 143-150
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  • 56
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    Inversion of vegetation canopy reflectance models for estimating agronomic variables. II - Use of angle transforms and error analysis as illustrated by Suits' model (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The technique for inverting a vegetation canopy reflectance model described earlier (Goel and Strebel, 1983) is investigated further. The novel concept of an 'angle transform' is introduced. This concept allows the formation of functions of reflectances at different view zenith and azimuth angles, which are either sensitive or insensitive to a certain agronomic parameter. A proper combination of these functions can allow determination of all the important agronomic and spectral parameters from measured canopy reflectance data. The technique is demonstrated using Suits' (1972) model for homogeneous canopies. It is shown that leaf area index, leaf reflectance and transmittance, and average leaf angle all can be determined from the canopy reflectance at a set of selected view zenith and azimuth angles. A sensitivity analysis of the calculated values to the errors in the data is also carried out. Guidelines are formulated for the number and types of observations required to obtain the values of a particular canopy variable to within a given degree of accuracy for a given level of error in the measurement of canopy reflectance.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Remote Sensing of Environment (ISSN 0034-4257); 14; 77-111
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  • 57
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    Ultraviolet spectra of planetary nebulae. X - Physical conditions in the compact planetary nebula Sw St 1 (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Photoelectric visual and ultraviolet observations of the compact planetary nebula Sw St 1 are analyzed. The electron density, determined from the C III 1907/1909 A line ratio, is N(e) = (1.1 + or - 0.1) x 10 to the 5th/cu cm, consistent with the high emission measure and high critical frequency determined from observations of the thermal radio emission. The C/O abundance ratio in the nebula is found to be N(C)/N(O) = 0.72 + or - 0.1, i.e. the envelope is oxygen-rich, as suggested by the identification of the silicate feature in the 8-13 micron infrared spectrum. Difficulties remain in accurately determining the reddening constant to the nebula and its electron temperature.
    Keywords: ASTRONOMY
    Type: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 206; 293-304
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    Mapping of glacial landforms from Seasat radar images (1984)
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    Publication Date: 2011-08-19
    Description: Glacial landforms in the drumlin drift belt of Ireland and the Alaska Range can be identified and mapped from Seasat synthetic-aperture radar (SAR) images. Drumlins cover 60 percent of the Ireland scene. The width/length ratio of individual drumlins can be measured on the SAR images, allowing regional differences in drumlin shape to be mapped. This cannot be done with corresponding Landsat multispectral scanner (MSS) images because of lower spatial resolution and because of shadowing effects that vary seasonally. The Alaska scene shows the extent and nature of morphological features such as medial and lateral moraines, stagnant ice, and fluted ground moraine in glaciated valleys. Perception of these features on corresponding Landsat MSS images is limited by seasonal diffrences in solar illumination. Because SAR is not affected by such differences or by cloud cover, it is particularly well suited for monitoring glacial movement. The disadvantage of distorted high-relief features on Seasat SAR images can be reduced in future SAR systems by modifying the radar illumination geometry.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Quaternary Research (ISSN 0033-5894); 22; 314-327
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    Statistical analysis of Thematic Mapper Simulator data for the geobotanical discrimination of rock types in southwest Oregon (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: An evaluation of Thematic Mapper Simulator (TMS) data for the geobotanical discrimination of rock types based on vegetative cover characteristics is addressed in this research. A methodology for accomplishing this evaluation utilizing univariate and multivariate techniques is presented. TMS data acquired with a Daedalus DEI-1260 multispectral scanner were integrated with vegetation and geologic information for subsequent statistical analyses, which included a chi-square test, an analysis of variance, stepwise discriminant analysis, and Duncan's multiple range test. Results indicate that ultramafic rock types are spectrally separable from nonultramafics based on vegetative cover through the use of statistical analyses.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: IEEE Transactions on Geoscience and Remote Sensing (ISSN 0196-2892); GE-22; 525-530
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  • 60
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    Feature selection and the information content of Thematic Mapper simulator data for forest structural assessment (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: An assessment is made of the information content of Thematic Mapper Simulator (TMS) data for the case of a forested region, in order to determine the sensitivity of such data to forest crown closure and tree size class. Principal components analysis and Monte Carlo simulation indicated that channels 4, 7, 5 and 3 were optimal for four-channel forest structure analysis. As the number of channels supplied to the Monte Carlo feature selection routine increased, classification accuracy increased. The greatest sensitivity to the forest structural parameters, which included succession within clearcuts as well as crown closure and size class, was obtained from the 7-channel TMS data.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: IEEE Transactions on Geoscience and Remote Sensing (ISSN 0196-2892); GE-22; 482-489
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    A summary of the history of the development of automated remote sensing for agricultural applications (1984)
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    Publication Date: 2011-08-19
    Description: An historical account is given of the development of technology for the processing of satellite-acquired multispectral data aimed at the identification of the type, condition, and ontogenic stages of agricultural areas. During 1972 and 1973, research established the feasibility of automating digital classification for the processing of large volumes of Landsat MSS data. This capability was successfully demonstrated during the Large Area Crop Inventory Experiment, which estimated wheat crop production on a global basis. This achievement in turn led to the Agriculture and Resources Inventory Surveys Through Aerospace Remote Sensing, which investigated other portions of the electromagnetic spectrum and expanded the study of key commercial crops in important agricultural areas.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: IEEE Transactions on Geoscience and Remote Sensing (ISSN 0196-2892); GE-22; 473-482
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  • 62
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    Radioastronomical observations of comets IRAS-Araki-Alcock (1983d) and Sugano-Saigusa-Fujikawa (1983e) (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Continuum and spectral-line radio observations of the comets IRAS-Araki-Alcock and Sugano-Saigusa-Fujikawa obtained at a number of observatories during May and June, 1983, are compiled in tables and briefly characterized. The species NH3, H2O, CO, and HCN are considered in detail; visible-range observations of CN are compared; and the implications of the results and the experience gained in performing and coordinating the observations for the detection of important species in other comets, especially Halley's Comet, are explored.
    Keywords: ASTRONOMY
    Type: Icarus (ISSN 0019-1035); 60; 215-220
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  • 63
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    A search at the millijansky level for milli-arcsecond cores in a complete sample of radio galaxies (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A complete sample of 26 extended radio galaxies was observed at 2.29 GHz with the Mark III VLBI system. The fringe spacing was about 3 milli-arcsec, and the detection limit was about 2 millijanskys. Half of the galaxies were found to possess milli-arcsec radio cores. In all but three sources, the nuclear flux density was less than 0.04 of the total flux density. Galaxies with high optical luminosity (less than -21.2) were more likely than less luminous galaxies to contain a detectable milliparcsec radio core (69 percent vs. 20 percent). For objects with arcsec cores, 80 percent were found to have a milli-arcsec core, even though the milli-arcsec object did not always contribute the greater part of the arcsec flux density.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 284; 519-522
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  • 64
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    Metric-discontinuous zonal grid calculations using the Osher scheme (1984)
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    Publication Date: 2011-08-19
    Description: Computations on zonal grids - in particular, grids with metric discontinuities resulting from the interspersion of highly clustered regions with coarse regions - are possible using a fully conservative form of the Osher upwind scheme. These zonal grids can result from an abrupt clustering of points near solution discontinuities or near other flow features that require improved resolution. The zonal approach is shown to capture shocks with almost 'shock-fitting' quality but with minimal effort. Results for inviscid flow, including quasi-one-dimensional nozzle flow, supersonic flow over a cylinder, and blast-wave diffraction by a ramp, are presented. These calculations demonstrate the powerful capabilities of the Osher scheme used in conjunction with zonal grids in simulating flow fields with complex shock patterns.
    Keywords: AERODYNAMICS
    Type: Computers and Fluids (ISSN 0045-7930); 12; 3, 19
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  • 65
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    Use of Landsat-derived profile features for spring small-grains classification (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The present model for the temporal behavior of agricultural greenness is applied to the extraction of Landsat-derived profile features, distinguishing small from large grain crops. An additional feature derivable from the temporal behavior of the ratio of greenness to brightness is noted which aids in the separation of crops from other vegetation. A limited training set of 20 pure pixels/class, obtained from ground data, is subjected to the Ho-Kashyap (1965) linear classifier. The initial correct classification value for pure pixels of about 85 percent drops to 75 percent for all Landsat pixels.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: International Journal of Remote Sensing (ISSN 0143-1161); 5; 783-797
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  • 66
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    Improved classification of small-scale urban watersheds using thematic mapper simulator data (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The utility of Landsat MSS classification methods in the case of small, highly urbanized hydrological basins containing complex land-use patterns is limited, and is plagued by misclassifications due to the spectral response similarity of many dissimilar surfaces. Landsat MSS data for the Conley Creek basin near Atlanta, Georgia, have been compared to thematic mapper simulator (TMS) data obtained on the same day by aircraft. The TMS data were able to alleviate many of the recurring patterns associated with MSS data, through bandwidth optimization, an increase of the number of spectral bands to seven, and an improvement of ground resolution to 30 m. The TMS is thereby able to detect small water bodies, powerline rights-of-way, and even individual buildings.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: International Journal of Remote Sensing (ISSN 0143-1161); 5; 761-770
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  • 67
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    Spring wheat-leaf phytomass and yield estimates from airborne scanner and hand-held radiometer measurements (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: An attempt has been made to relate hand-held radiometer measurements, and airborne multispectral scanner readings, with both different wheat stand densities and grain yield. Aircraft overflights were conducted during the tillering, stem extension and heading period stages of growth, while hand-held radiometer readings were taken throughout the growing season. The near-IR/red ratio was used in the analysis, which indicated that both the aircraft and the ground measurements made possible a differentiation and evaluation of wheat stand densities at an early enough growth stage to serve as the basis of management decisions. The aircraft data also corroborated the hand-held radiometer measurements with respect to yield prediction. Winterkill was readily evaluated.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: International Journal of Remote Sensing (ISSN 0143-1161); 5; 771-781
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  • 68
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    Granitic terrains viewed remotely by Shuttle infrared radiometry - Some compositional predictions (1984)
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    Publication Date: 2011-08-19
    Description: Ratios of intensities of near-infrared spectral bands, measured in reflectance, quantitatively predict the iron content of granitic rocks. Such data from the 1.60- and 1.05-micron bands of the Shuttle multispectral infrared radiometer have been used to study granitic rocks along orbits crossing Baja California, Mexico, and the Eastern Desert of Egypt. Both regions are arid and relatively to essentially free of vegetation, and there is no indication in the spectra that surface chemical alteration masks the true composition of the unweathered rock. Predicted values of iron are consistent with known compositional types of most of the rocks along the orbital paths. Results demonstrate that the near-infrared method used is a powerful technique to average the variability of these rocks on the scales of meters to kilometers.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Journal of Geophysical Research (ISSN 0148-0227); 89; 9439-944
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  • 69
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    Retrieval of vertical moisture profiles with microwave radiometry (1984)
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    Publication Date: 2011-08-18
    Description: A statistical correlation technique is applied to the retrieval of vertical moisture profiles from downlooking radiometric measurements of atmospheric radiation at microwave wavelengths. Only an optimum subset of available radiometer channels is selected for estimating water vapor at specific pressure levels. To test its validity the algorithm was applied, in a numerical experiment, to 50 independent tropical radiosondes over a sea surface. It was also used to retrieve continuous sequences of atmospheric moisture profiles from a set of data obtained with a 4-channel microwave radiometer carried aboard an aircraft over a land surface.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ESA IGARSS 84. Remote Sensing: From Res. towards Operational Use, Vol. 1; p 449-451
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  • 70
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    Comparison of sea surface wind speed fields by SEASAT radar altimeter, scatterometer and scanning multichannel microwave radiometer with an emphasis on the Southern Ocean (1984)
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    Publication Date: 2011-08-18
    Description: The SEASAT altimeter (ALT), scatterometer (SASS), and scanning microwave multichannel radiometer (SMMR) measured sea surface wind speed. During the satellite lifetime from June to October 1978, the Austral winter, the highest wind speeds were recorded in the Southern Ocean. Three-month, monthly, and three-day surface wind speed fields deduced from the three Seasat wind speed sensors are compared. The monthly and three-day fields show a pronounced mesoscale (1000 km) variability in wind speed. At all space and time scales analyzed, differences of 40% are found in the magnitude of the wind speed features, with the ALT consistently yielding the lowest wind speed and the SMMR the highest.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ESA IGARSS 84. Remote Sensing: From Res. towards Operational Use, Vol. 1; p 403-409
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  • 71
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    Passive microwave characteristics of the Bering Sea ice cover during Marginal Ice Zone Experiment (MIZEX) West (1984)
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    Publication Date: 2011-08-18
    Description: Passive microwave measurements of the Bering Sea were made with the NASA CV-990 airborne laboratory during February. Microwave data were obtained with imaging and dual-polarized, fixed-beam radiometers in a range of frequencies from 10 to 183 GHz. The high resolution imagery at 92 GHz provides a particularly good description of the marginal ice zone delineating regions of open water, ice compactness, and ice-edge structure. Analysis of the fixed-beam data shows that spectral differences increase with a decrease in ice thickness. Polarization at 18 and 37 GHz distinguishes among new, young, and first-year sea ice types.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ESA IGARSS 84. Remote Sensing: From Res. towards Operational Use, Vol. 1; p 379-384
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  • 72
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    Observation of variations in the composition of sea ice in the Greenland MIZ during early summer 1983 with the Nimbus-7 SMMR (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Data acquired with the Scanning Multichannel Microwave Radiometer (SMMR) on board the Nimbus-7 Satellite for a six-week period in Fram Strait were analyzed with a procedure for calculating sea ice concentration, multiyear fraction, and ice temperature. Calculations were compared with independent observations made on the surface and from aircraft to check the validity of the calculations based on SMMR data. The calculation of multiyear fraction, which was known to be invalid near the melting point of sea ice, is discussed. The indication of multiyear ice is found to disappear a number of times, presumably corresponding to freeze/thaw cycles which occurred in this time period.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ESA IGARSS 84. Remote Sensing: From Res. towards Operational Use, Vol. 1; p 373-378
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  • 73
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    Soil moisture from temperature measurements at the Earth's surface, update (1984)
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    Publication Date: 2011-08-18
    Description: Soil moisture budgets at the Earth's surface were investigated based on soil and atmospheric temperature variations. A number of data sets were plotted and statistically analyzed in order to accentuate the existence and the characteristics of mesoscale soil temperature extrema variations and their relations to other parameters. The correlations between diurnal temperature extrema for air and soil in drought and non-drought periods appear to follow different characteristic patterns, allowing an inference of soil moisture content from temperature data. The recovery of temperature extrema after a precipitation event also follows a characteristic power curve rise between two limiting values which is an indicator of evaporation rates. If these indicators are applied universally to regional temperature data, soil moisture content or drought conditions can be inferred directly from temperature measurements.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Res. Activities of the Geodyn. Branch; 6 p
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  • 74
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    Accuracy of mapping the Earth's gravity field fine structure with a spaceborne gravity gradiometer mission (1984)
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    Publication Date: 2011-08-18
    Description: The spaceborne gravity gradiometer is a potential sensor for mapping the fine structure of the Earth's gravity field. Error analyses were performed to investigate the accuracy of the determination of the Earth's gravity field from a gravity field satellite mission. The orbital height of the spacecraft is the dominating parameter as far as gravity field resolution and accuracies are concerned.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Res. Activities of the Geodyn. Branch; 6 p
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  • 75
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    SEASAT altimetry for surface height of inland seas (1984)
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    Publication Date: 2011-08-18
    Description: The capability of spaceborne altimetry to record the level, or monitor changes in the level, of inland seas was assessed. SEASAT altimetry data from Lake Baikal in Siberia; the Caspian, Black, and Aral Seas in the southern Soviet Union; the Great Salt Lake in the United States; lakes and reservoirs in northwestern and central China; and snow cover in northwestern India and on the Tibetan Plateau were examined.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Res. Activities of the Geodyn. Branch; 6 p
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  • 76
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    New infrared observations of IRS1, IRS3, and the adjacent nebula in the OMC-2 cluster (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Observations of the infrared cluster of low luminosity protostars in Orion Molecular Cloud 2 (OMC2) are reported. Results show that the asymmetric distribution of the extended emission seen about IRS1 is another infrared reflection nebula. Energy distributions show that the spectral shape is fairly constant throughout the nebula which indicates there is little internal extinction within this region. Integrated surface brightness values show that the nebula is 5 times brighter than IRS1 at K. Energy distributions show that IRS1 has a more pronounced ice band absorption feature at 3.1 micron; suggesting that there is more extinction along the direct line of sight to IRS1 than along a line from IRS1 to the scattering grains and then to the observer. The distribution of the extended emission around IRS1 is similar to the reflection nebula seen in NGC 7538 (Werner et al. 1979). The asymmetric shapes of the two nebulae are similar and in each case there is excess extinction along line of sight to the illuminating source.
    Keywords: ASTRONOMY
    Type: Royal Observatory Lab. and Observational Infrared Spectra of Interstellar Dust; p 162-166
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  • 77
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    Time dependent land and vegetation canopy temperatures (1984)
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    Publication Date: 2011-08-18
    Description: A simple interactive biosphere is presented based on an electrical analog of turbulent transport processes that produce heat and moisture fluxes between land and the atmosphere. A network of resistances that effect temperature or vapor pressure fluxes are identified and entered into the quasi steady state equations. A set of solutions that depict a realistic diurnal cycle is included.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Res. Rev., 1983; p 285-291
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  • 78
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    Lifting surface theory for a helicopter rotor in forward flight (1984)
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    Publication Date: 2011-08-19
    Description: A lifting surface theory was developed for a helicopter rotor in forward flight for compressible and incompressible flow. The method utilizes the concept of the linearized acceleration potential and makes use of the vortex lattice procedure. Calculations demonstrating the application of the method are given in terms of the lift distribution on a single rotor, a two-bladed rotor, and a rotor with swept-forward and swept-back tips. In addition, the lift on a rotor which is vibrating in a pitching mode at 4/rev is given. Compressibility effects and interference effects for a two-bladed rotor are discussed.
    Keywords: AERODYNAMICS
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  • 79
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    Transient dips of Cygnus X-1 observed from Tenma (1984)
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    Publication Date: 2011-08-19
    Description: The transient intensity dips of the binary system Cyg X-1 have been observed, using the gas scintillation proportional counter (GSPC) array onboard the Tenma X-ray astronomy satellite. The duration of the dips was in the range from several seconds to 10 minutes, with several dips occurring as much as 15 h before the superior conjunction. Within the dips, complex structures were observed with time scales of several seconds, and, in at least one case, shorter than two seconds. For a dip lasting longer than 10 minutes, a high-quality spectrum was obtained which reveals the K-absorption edge of iron at 7.18 + or - 0.18 keV. On the basis of the observed absorption, it is suggested that the dips are caused by absorption due to relatively cool matter (less than about 30,000 k); the low-energy excess observed during the dips is due either to an extended soft X-ray emitting corona or to partial obscuration of the X-ray source by multiple blobs. From the time structure of the dip, a blob size of the order of 10 to the 9th cm is derived.
    Keywords: ASTRONOMY
    Type: Astronomical Society of Japan, Publications (ISSN 0004-6264); 36; 4, 19
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  • 80
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    Changes in vegetation spectra with leaf deterioration under two methods of preservation (1984)
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    Publication Date: 2011-08-19
    Description: Changes in leaf spectra caused by mineralization under different conditions of preservation are measured using a three-band portable radiometer which simulates three Thematic Mapper bands 3, 4, and 5. Daily spectral measurements of white oak (Quercus alba) leaves did not distinguish among the fresh, bottled, and bagged vegetation in the spectral bands 3 and 5 for up to four days after collection. The reflected energy of the preserved vegetation increased thereafter, reportedly due to the loss of chlorophyll and dehydration. It is concluded that the measurement procedure is sufficiently sensitive as to discern documented patterns of variation in reflectance measurements.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Photogrammetric Engineering and Remote Sensing (ISSN 0099-1112); 50; 1737-174
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  • 81
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    An evaluation of simulated Thematic Mapper data and Landsat MSS data for discriminating suburban and regional land use and land cover (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: An airborne multispectral scanner, operating in the same spectral channels as the Landsat Thematic Mapper (TM), was used in a region east of Denver, CO, for a simulation test performed in the framework of using TM to discriminate the level I and level II classes. It is noted that at the 30-m spatial resolution of the Thematic Mapper Simulator (TMS) the overall discrimination for such classes as commercial/industrial land, rangeland, irrigated sod, irrigated alfalfa, and irrigated pasture was superior to that of the Landsat Multispectral Scanner, primarily due to four added spectral bands. For residential and other spectrally heterogeneous classes, however, the higher resolution of TMS resulted in increased variability within the class and a larger spectral overlap.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Photogrammetric Engineering and Remote Sensing (ISSN 0099-1112); 50; 1713-172
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  • 82
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    EROS main image file - A picture perfect database for Landsat imagery and aerial photography (1984)
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    Publication Date: 2011-08-19
    Description: The Earth Resources Observation System (EROS) Program was established by the U.S. Department of the Interior in 1966 under the administration of the Geological Survey. It is primarily concerned with the application of remote sensing techniques for the management of natural resources. The retrieval system employed to search the EROS database is called INORAC (Inquiry, Ordering, and Accounting). A description is given of the types of images identified in EROS, taking into account Landsat imagery, Skylab images, Gemini/Apollo photography, and NASA aerial photography. Attention is given to retrieval commands, geographic coordinate searching, refinement techniques, various online functions, and questions regarding the access to the EROS Main Image File.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Database (ISSN 0162-4105); 7; 35-52
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  • 83
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    IUE observations of the 'Butterfly' Nebula M2-9 (1984)
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    Publication Date: 2011-08-19
    Description: IUE observations of the peculiar 'Butterfy' nebula M2-9 indicate that it is not a normal planetary nebula. The ultraviolet spectrum is characterized by few emission lines and a weak continuum. Mg II 2800 A is the strongest emission line present and may be indicative of a binary nucleus. Lines of N v, Q I, N III, N IV, Si III, and C III are seen, but C IV and O III are conspicuous by their absence. T(e) = 10,250 + or - 400 K was determined for the core. Nitrogen in the core is found to be overabundant by about a factor of 5 over the solar value. M2-9 may be an object in the early stages of becoming a planetary nebula.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 287; 353-358
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  • 84
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    Sensitivity of thermal inertia calculations to variations in environmental factors (1984)
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    Publication Date: 2011-08-19
    Description: The sensitivity of thermal inertia (TI) calculations to errors in the measurement or parameterization of a number of environmental factors is considered here. The factors include effects of radiative transfer in the atmosphere, surface albedo and emissivity, variations in surface turbulent heat flux density, cloud cover, vegetative cover, and topography. The error analysis is based upon data from the Heat Capacity Mapping Mission (HCMM) satellite for July 1978 at three separate test sites in the deserts of the western United States. Results show that typical errors in atmospheric radiative transfer, cloud cover, and vegetative cover can individually cause root-mean-square (RMS) errors of about 10 percent (with atmospheric effects sometimes as large as 30-40 percent) in HCMM-derived thermal inertia images of 20,000-200,000 pixels.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Remote Sensing of Environment (ISSN 0034-4257); 16; 211-232
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  • 85
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    Cometary showers and unseen solar companions (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The possibility that an invisible solar companion passing through the Oort cloud every 28 Myr precipitates a sufficiently high rate of cometary collisions with the earth to account for periodic mass species extinctions recorded in the fossil record is discussed. A Monte Carlo simulation shows that any hypothesized 'death star' with a 28 Myr orbit would experience an average 10 percent change in period per orbit. Production of an 18-fold increase in cometary impacts would be associated with a 0.055 probability that a 10 km nucleus would hit the earth in a shower once every 510 Myr, longer than the proposed extinction periodicity. However, if the death star orbit has a 0.6 eccentricity and the Oort cloud is sufficiently densely populated, a 2 billion comet shower may be possible. A survey of large terrestrial impact craters indicates that 6-12 craters with diameters over 10 km originated in periodic showers. The extinctions in any case occur at 26 Myr periods and cannot be correlated with the 33 Myr period of recrossing the galactic plane, or with any other known phenomena.
    Keywords: ASTRONOMY
    Type: Nature (ISSN 0028-0836); 312; 380; Rep
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  • 86
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    Analysis of surface pressure distributions on two elliptic missile bodies (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Spacecraft and Rockets (ISSN 0022-4650); 21; 528-533
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  • 87
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    Evidence for material between Saturn's A and F rings from the Voyager 2 photopolarimeter experiment (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The region in the Saturn system between the F ring and the outer edge of the A ring is an area that appears, in images from the imaging experiment, to be virtually devoid of material except for three small satellites. Near the orbit of 1980S28, Atlas - the innermost satellite - the Voyager Photopolarimeter Stellar Occultation data show a discontinuity in count rate which marks a boundary between the tenuous material near the outer edge of the A ring and the orbit of Atlas. The data pertaining to this region have been examined with the aid of statistics and models generated from other similar ring structures. It is concluded that the discontinuity is real, implying the existence of tenuous material of normal optical depth of 0.01 to 0.006 in this region.
    Keywords: ASTRONOMY
    Type: Icarus (ISSN 0019-1035); 60; 409-415
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  • 88
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    1984 AB - A unique Mars-crossing asteroid (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Asteroid 1984 AB, discovered in January 1984, proved to be a unique object with a close dynamical relationship to Mars. A brief history of the discovery and subsequent 'evolution' of the orbit as it was refined is presented. The preliminary orbit of 1984 AB indicated that it might be a Mars Trojan, and an extended discussion of this interesting possibility is presented, but this hypothesis had to be dismissed after further observations had refined the orbit. The semimajor axis and orbital eccentricity are very similar to that of Mars. No other known Mars-crossing asteroid exists with an orbit as closely associated to Mars.
    Keywords: ASTRONOMY
    Type: Icarus (ISSN 0019-1035); 60; 404-408
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  • 89
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    A general perturbation approach for computational fluid dynamics (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 22; 1748-175
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  • 90
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    Mapping alluvial fans in Death Valley, California, using multichannel thermal infrared images (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Alluvial fans have been mapped in Death Valley, California using NASA's 8-12 micron six-channel airborne Thermal Infrared Multispectral Scanner (TIMS). Both composition and relative age differences were recognized. Age unit boundries are generally consistent with those obtained by conventional mapping. Composition was verified by field investigation and comparison with existing geologic maps. Bedrock and its young derived fan gravels have similar emissivities. The original composition of the fans is modified by differential erosion and weathering, permitting relative age mapping with TIMS.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Geophysical Research Letters (ISSN 0094-8276); 11; 1153-115
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  • 91
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    Active airborne infrared laser system for identification of surface rock and minerals (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Emissivity and reflectivity in the thermal infrared spectral region (8-13 microns) may be used to discriminate among rocks and minerals. Although considerable success has been achieved in remote sensing classification of rock types based on emissivity measurements made with NASA's Thermal Infreared Multispectral Scanner (TIMS), classification based on reflectivity offers several advantages: much narrower bandwidths are used, higher signal to noise ratios are possible, and measurements are little affected by surface temperature. As a demonstration, an airborne CO2 laser instrument was flown along the margin of Death Valley, California. Measurements of spectral reflectance collected with this device were compared with emissivity measurements made with the TIMS. Data from either instrument provided the means for recognizing boundaries between geologic units including different rock types and fan surfaces of different ages.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Geophysical Research Letters (ISSN 0094-8276); 11; 1149-115
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  • 92
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    A radar study of Comet IRAS-Araki-Alcock 1983d (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Radar echoes from Comet IRAS-Araki-Alcock at wavelengths 3.54 and 12.9 cm indicate that the comet's nucleus is very rough on a scale larger than the radar wavelengths; however, the low polarization ratio (25 percent at 3.54 cm) indicates that the scattering is not dominated by multiple reflections, internal reflections, or large abundances of sharp edges, cracks, and pits. The shape of the nucleus probably departs greatly from a sphere with average radii near 3-4 km. The nucleus does not appear to look significantly different from a number of Apollo and Amor asteroids except that: (1) there is a suggestion that minor structure moves rapidly across the spectra, and (2) the debris not gravitationally bound to the comet was detected, and contributes 25 percent of the total radar cross section at the 12.9-cm wavelength. Other considerations suggest that the pole was at least 45 deg away from the line of sight on two days of observation, and that the rotation period is approximately 1-2 days.
    Keywords: ASTRONOMY
    Type: Astronomical Journal (ISSN 0004-6256); 89; 1745-175
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  • 93
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    Assessment of Landsat multispectral scanner spectral indexes for monitoring arid rangeland (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Correlations between spectral indices and vegetation parameters in south-central New Mexico were used to determine the utility of Landsat Multispectral Scanner (MSS) spectral indices in arid rangeland monitoring. In addition, spectral index change for 1976-1980 was calculated from retrospective MSS data and compared with qualitative ground truth in order to evaluate vegetation change detection by means of spectral indices. Brightness index change consistently differentiated between cover increase and decrease, but index change appears to have been offset from true cover change; this may at least partly be attributed to the failure of the methods used to standardize MSS scenes for differences in sensor response. Green vegetation indices, by contrast to brightness indices, failed to consistently differentiate between cover increase and decrease.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: IEEE Transactions on Geoscience and Remote Sensing (ISSN 0196-2892); GE-22; 512-519
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  • 94
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    Considerations of and improvements to large-scale vegetation monitoring (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The NOAA-7 polar orbiting sun-synchronous operational satellite carries the 5-channel advanced very high-resolution radiometer which acquires data globally at a spatial resolution of 4 km on a daily basis. These data provide a means for frequently monitoring global vegetation at continental scales. Techniques for compositing and cloud screening a green leaf density vegetation index product for Africa are presented for 9 sequential days beginning August 16, 1982 and are compared with a semi-operational vegetation index product produced by NOAA.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: IEEE Transactions on Geoscience and Remote Sensing (ISSN 0196-2892); GE-22; 496-502
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  • 95
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    A solar spectral line list between 10 and 200 A modified for application to high spectral resolution X-ray astronomy (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A spectral line list for the 10-200 A range is developed from existing solar spectra for application to high spectral resolution measurements of astrophysical plasmas. The solar spectral line lists are merged into a single comprehensive list. The effect of the solar emission measure distribution is removed from the line intensities, which results in a set of emission rates for the lines that can be applied to many optically thin, low density high temperature plasmas in ionization equilibrium. In addition to the measured solar lines, 250 theoretical lines are added to this list. These lines fall in wavelength regions where the existing solar lists have few lines because of limitations in instrumental sensitivity. Also, some lines have been added because the sun has very little plasma at temperatures of about one million K, and consequently these lines are weak or absent in solar spectra. The entire list contains about 600 lines. Finally, predicted spectra of the two RS CVn stars, alpha Aur (Capella) and UX Ari, are presented at 1 and 0.25 A spectral resolution. Also, the solar spectrum is shown at 1 A resolution, and the emission rate spectrum (spectrum not modified by an emission measure distribution) is shown at very high spectral resolution. The predicted spectra for Capella and UX Ari are based on results obtained from the Einstein and International Ultraviolet Explorer (IUE) spacecraft.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal Supplement Series (ISSN 0067-0049); 56; 67-89
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  • 96
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    A comparison between active and passive sensing of soil moisture from vegetated terrains (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A comparison between active and passive sensing of soil moisture over vegetated areas is studied via scattering models. In active sensing three contributing terms to radar backscattering can be identified: (1) the ground surface scatter term; (2) the volume scatter term representing scattering from the vegetation layer; and (3) the surface volume scatter term accounting for scattering from both surface and volume. In emission three sources of contribution can also be identified: (1) surface emission; (2) upward volume emission from the vegetation layer; and (3) downward volume emission scattered upward by the ground surface. As ground moisture increases, terms (1) and (3) increase due to increase in permittivity in the active case. However, in passive sensing, term (1) decreases but term (3) increases for the same reason. This self conpensating effect produces a loss in sensitivity to change in ground moisture. Furthermore, emission from vegetation may be larger than that from the ground. Hence, the presence of vegetation layer causes a much greater loss of sensitivity to passive than active sensing of soil moisture.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Scattering Models in the Microwave Regime; 35 p
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  • 97
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    Scattering from randomly oriented circular discs with application to vegetation (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A vegetation layer is modeled by a collection of randomly oriented circular discs over a half space. The backscattering coefficient from such a half space is computed using the radiative transfer theory. It is shown that significantly different results are obtained from this theory as compared with some earlier investigations using the same modeling approach but with restricted disc orientations. In particular, the backscattered cross polarized returns cannot have a fast increasing angular trend which is inconsistent with measurements. By setting the appropriate angle of orientation to zero the theory reduces to previously published results. Comparisons are shown with measurements taken from milo, corn and wheat and good agreements are obtained for both polarized and cross polarized returns.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Scattering Models in the Microwave Regime; 10 p
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  • 98
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    Reduction of astrographic catalogues (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: An automatic program for the reduction of overlapping Carte du Ciel plates is described. The projection and transformation equations are given and the RAA subprogram flow is outlined. The program was applied to two different sets of data, namely to nine overlapping plates of the Cape Zone of the CdC, and to fifteen plates taken with the CIDA-refractor of the open cluster Tr10.
    Keywords: ASTRONOMY
    Type: JPL Cometary Astrometry; p 99-104
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  • 99
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    Obtaining accurate comet positions despite some inaccurate catalog stars (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: From an astrographic negative a grid is determined from measurement of all the reference stars and using their catalog positions, and other grids from selections of reference stars. These grids are determined from many stars, and individual stars will have errors with respect to the grid. There are ways to identify stars X that are not at their cataloged position: (1) determine the focal length of the telescope from the measurements of each pair of stars and look for discordant results; (2) stars X are several arcseconds off the grid, and the other stars fit better when stars X do not help determine the grid; and (3) the grid is stretched or distorted to include the stars X. Fifteen to twenty percent of the stars in the S.A.O. catalog are 1.5 seconds or more off their catalog positions. An interactive session with a computer can find and eliminate these errant stars and result in more accurate comet positions.
    Keywords: ASTRONOMY
    Type: JPL Cometary Astrometry; p 96-98
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  • 100
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    Desired characteristics of catalogs for cometary astrometry (1984)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Reference star catalogs for cometary astrometry have to provide an all-sky coverage with suitable stellar density and limiting magnitude on a fundamental coordinate system. A general catalog meeting all these requirements will not be available for a foreseen timescale. The suitability of various existing catalogs for cometary astrometry is discussed.
    Keywords: ASTRONOMY
    Type: JPL Cometary Astrometry; p 87-92
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