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  • Life and Medical Sciences  (3,416)
  • Organic Chemistry  (3,406)
  • EARTH RESOURCES AND REMOTE SENSING  (3,277)
  • AERODYNAMICS  (2,091)
  • 1980-1984  (12,190)
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  • 1
    Publication Date: 2011-10-14
    Description: The test capabilities of the Stability Wind Tunnel of the Virginia Polytechnic Institute and State University are described, and calibrations for curved and rolling flow techniques are given. Oscillatory snaking tests to determine pure yawing derivatives are considered. Representative aerodynamic data obtained for a current fighter configuration using the curved and rolling flow techniques are presented. The application of dynamic derivatives obtained in such tests to the analysis of airplane motions in general, and to high angle of attack flight conditions in particular, is discussed.
    Keywords: AERODYNAMICS
    Type: AGARD Dyn. Stability Parameters; 13 p
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  • 2
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    In:  CASI
    Publication Date: 2009-11-16
    Description: Background information and exercises are provided to: (1) establish or expand understanding of the concepts, methods, and terminology of computer processing of image producing data; (2) develop insight into the advantages of computer based image processing compared with the photointerpretation approach for processing, classifying, interpreting, and applying remote sensing data; (3) foster a broad perspective on the principal of the main techniques for image enhancement, pattern recognition, and thematic classification; (4) appreciate the pros and cons of batch and interactive modes of image analysis; (5) examine and evaluate some specific computer generated products for subscenes in Pennsylvania and New Jersey; and (6) interrelate these particular examples of output with more theoretical explanations of computer processing strategies and procedures.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: The LANDSAT Tutorial Workbook; p 145-232
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  • 3
    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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  • 4
    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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  • 5
    Publication Date: 2006-02-14
    Description: A KC-135A aircraft equipped with wing tip winglets was flight tested to demonstrate and validate the potential performance gain of the winglet concept as predicted from analytical and wind tunnel data. Flight data were obtained at cruise conditions for Mach numbers of 0.70, 0.75, and 0.80 at a nominal altitude of 36,000 ft. and winglet configurations of 15 deg cant/-4 deg incidence, 0 deg cant/-4 deg incidence, and baseline. For the Mach numbers tested the data show that the addition of winglets did not affect the lifting characteristics of the wing. However, both winglet configurations showed a drag reduction over the baseline configuration, with the best winglet configuration being the 15 deg cant/-4 deg incidence configuration. This drag reduction due to winglets also increased with increasing lift coefficient. It was also shown that a small difference exists between the 15 deg cant/-4 deg incidence flight and wind tunnel predicted data. This difference was attributed to the pillowing of the winglet skins in flight which would decrease the winglet performance.
    Keywords: AERODYNAMICS
    Type: KC-135 Winglet Program Rev.; p 103-116
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  • 6
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    In:  CASI
    Publication Date: 2006-02-14
    Description: A joint NASA/USAF program was conducted to accomplish the following objectives: (1) evaluate the benefits that could be achieved from the application of winglets to KC-135 aircraft; and (2) determine the ability of wind tunnel tests and analytical analysis to predict winglet characteristics. The program included wind-tunnel development of a test winglet configuration; analytical predictions of the changes to the aircraft resulting from the application of the test winglet; and finally, flight tests of the developed configuration. Pressure distribution, loads, stability and control, buffet, fuel mileage, and flutter data were obtained to fulfill the objectives of the program.
    Keywords: AERODYNAMICS
    Type: KC-135 Winglet Program Rev.; p 1-46
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  • 7
    Publication Date: 2006-02-14
    Description: A full-scale winglet flight test on a KC-135 airplane with an upper winglet was conducted. Data were taken at Mach numbers from 0.70 to 0.82 at altitudes from 34,000 feet to 39,000 feet at stabilized flight conditions for wing/winglet configurations of basic wing tip, 15/-4 deg, 15/-2 deg, and 0/-4 deg winglet cant/incidence. An analysis of selected pressure distribution and data showed that with the basic wing tip, the flight and wind tunnel wing pressure distribution data showed good agreement. With winglets installed, the effects on the wing pressure distribution were mainly near the tip. Also, the flight and wind tunnel winglet pressure distributions had some significant differences primarily due to the oilcanning in flight. However, in general, the agreement was good. For the winglet cant and incidence configuration presented, the incidence had the largest effect on the winglet pressure distributions. The incremental flight wing deflection data showed that the semispan wind tunnel model did a reasonable job of simulating the aeroelastic effects at the wing tip. The flight loads data showed good agreement with predictions at the design point and also substantiated the predicted structural penalty (load increase) of the 15 deg cant/-2 deg incidence winglet configuration.
    Keywords: AERODYNAMICS
    Type: KC-135 Winglet Program Rev.; p 47-102
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  • 8
    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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  • 9
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    In:  CASI
    Publication Date: 2006-04-16
    Description: Images characteristics of geographic regions other than the northeastern part of the United States are presented for interpretation. Pre- and post-eruption imagery of Mt. St. Helens volcano serves to demonstrate the advantages of thermal infrared sensing, and the potential for developing a timely, decision oriented thematic map to be used in solving drought-related problems in Upper Volta is examined to show the applicability of satellite remote sensing in all geographic areas.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: The LANDSAT Tutorial Workbook; p 455-475
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  • 10
    Publication Date: 2006-04-12
    Description: The 1980 eruptions of Mount St. Helens in southeast Washington resulted in a pronounced effect on the surface and ground water resources of the state. In response to the volcanic activity, the U.S. Geological Survey intensified statewide surface and ground water sampling programs to determine the nature and magnitude of the volcanic-induced variations. Streams to the east of Mount St. Helens received the major ash fallout. Chemical effects were best noted in smaller streams sampled 60 to 70 miles northeast of Mount St. Helens. The chemical variations observed were pronounced but short lived. Sulfate and chloride increases in anionic composition were prevalent immediately following the eruption; however, the original bicarbonate predominance was again attained within several days. Suspended iron and aluminum concentrations were similarly elevated during the period of greatest ash deposition (highest turbidity); however, the dissolved concentrations remained relatively constant. Depressions of pH were minor and short lived. Streams draining to the south, tributaries to the Columbia river, showed little observable changes in water chemistry. Streams draining to the west (Toutle river and its tributaries) were compositionally affected by the various volcanic activities. Chloride and sulfate anion percentage exceeded the bicarbonate percentage up to one month following the eruption period. Streams and lakes sampled in the immediate vicinity of Mount St. Helens, in addition to trace metals, contained organic compounds derived from decomposing wood buried in the debris deposits. This organic material may constitute a significant source of organic compounds to surface and ground water for some time to come.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: NASA. Langley Research Center Atmospheric Effects and Potential Climatic Impact of the 1980 Eruptions of Mt. St. Helens; p 43-46
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  • 11
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    In:  CASI
    Publication Date: 2006-04-16
    Description: The benefits-to-cost ratio of satellite remote sensing, both as a substitute for conventional methods of monitoring and assessing resources, and as a supplement to these methods is examined using a model which analyzes the cost of aerial photography versus satellite scanner for producing and interpreting an image of the Earth's surface sized to LANDSAT dimensions. Examples of cost savings are tabulated for ground surveys, aerial photos, and LANDSAT. Possible additional benefits from LANDSAT D are assessed. The way in which satellites fit into more comprehensive models for resources management is discussed. It is shown that remote sensing is but one essential component in a complex system that aggregates technical. Socioeconomics, political, cultural, and other factors in the human decision process.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: The LANDSAT Tutorial Workbook; p 389-407
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  • 12
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    In:  CASI
    Publication Date: 2006-04-16
    Description: Computer processing facilitates extraction of information from every pixel by executing a variety of functional operations, called processed algorithms, in general or specialized routines. The best results are obtained when data from more than one multispectral band are used together. Multivariate tatistical analysis, computer tape characteristics, processing modes, and a choice of systems (batch or interactive) are discussed. The major operations in computer processing elaborated include: preprocessing, enhancement, effects of rationing, and classification. Techniques for multisource data correlation are considered with emphasis on geobased systems.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: The LANDSAT Tutorial Workbook; p 421-453
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  • 13
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    In:  CASI
    Publication Date: 2006-04-16
    Description: Learning objectives include: (1) developing an understanding of the implications of the term "near surface observations"; (2) associating the appearance of large ground features as seen in satellite imagery with their appearance as seen from the ground; (3) grasping criteria and procedures for selecting training sites on the ground for use in supervised classification; (4) running through an example of training site selection; (5) becoming familiar with several methods of accuracy assessment; (6) becoming aware of the approach and value of making supporting measurements of the spectral and physical properties of materials on the ground and from aircraft; (7) taking note of the different types of instruments used in making specific ground measurements; and (8) appreciating the rationale underlying laboratory and field studies on or near the Earth's surface for the purpose of developing new sensor systems.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: The LANDSAT Tutorial Workbook; p 233-276
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  • 14
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    In:  CASI
    Publication Date: 2006-04-16
    Description: Learning objectives include: (1) developing a facility for applying conventional techniques of photointerpretation to small scale (satellite) imager; (2) promoting the ability to locate, identify, and interpret small natural and man made surface features in a LANDSAT image; (3) using supporting imagery, such as aerial and space photography, to conduct specific applications analyses; (4) learning to apply change detection techniques to recognize and explain transient and temporal events in individual or seasonal imagery; (5) producing photointerpretation maps that define major surface units, themes, or classes; (6) classifying or analyzing a scene for specific discipline applications in geology, agriculture, forestry, hyrology, coastal wetlands, and environmental pollution; and (7) evaluating both advantages and shortcomings in relying on the photointerpretive approach (rather than computer based analytical approach) for extracting information from LANDSAT data.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: The LANDSAT Tutorial Workbook; p 101-143
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  • 15
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    In:  CASI
    Publication Date: 2006-04-16
    Description: Activities are provided for: (1) developing insight into the way in which the LANDSAT MSS produces multispectral data; (2) promoting understanding of what a "pixel" means in a LANDSAT image and the implications of the term "mixed pixel"; (3) explaining the concept of spectral signatures; (4) deriving a simple signature for a class or feature by analysis: of the four band images; (5) understanding the production of false color composites; (6) appreciating the use of color additive techniques; (7) preparing Diazo images; and (8) making quick visual identifications of major land cover types by their characteristic gray tones or colors in LANDSAT images.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: The LANDSAT Tutorial Workbook; p 81-99
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  • 16
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    Publication Date: 2006-04-16
    Description: Learning objectives of the activities provided include: (1) reading the annotation of a LANDSAT image; (2) becoming acquainted with the characteristics of 1:1,000,000 scale transparencies and prints of MSS images; (3) noting the general information visible in LANDSAT photo products; (4) observing changes of appearance of any ground feature or class in the black and white images made from the four MSS bands and the characteristic color of each class in color composites; (5) determining the degree to which a LANDSAT image meets map accuracy standards and can be fitted to map projections; (6) assessing the effects of LANDSAT enlargements and scale changes and of the limitations of satellite resolution relative to aerial photos; (7) observing the influence of time of acquisition (season) on a scene; (8) getting a feel for image quality as dependent on processing and photoreproduction; (9) appreciating the characteristics of the RBV and thermal band imagery obtained from LANDSAT-3; and (10) becoming familiar with certain attributes of adjacent LANDSAT images which permit them to be joined in mosaics and to be viewed in stereo.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: The LANDSAT Tutorial Workbook; p 39-80
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  • 17
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    Publication Date: 2006-04-16
    Description: The primary LANDSAT mission and the system requirements are summarized and pertinent parameters of the spacecraft, its orbit, and payload are tabulated. The history acquisition to entry into the archives for storage and product generation and dissemination is recounted. The LANDSAT D data handling plan is discussed showing requirements for both the MSS CCT and the thematic mapper CCT.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: The LANDSAT Tutorial Workbook; p 409-419
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  • 18
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    Publication Date: 2006-04-16
    Description: The term remote sensing is defined as well as ideas such as class, pattern, feature, pattern recognition, feature extraction, and theme. The electromagnetic spectrum is examined especially those wavelength regions available to remote sensing. Relevant energy and wave propagation laws are discussed and the characteristics of emitted and reflected radiation and their detection are investigated. The identification of classes by their spectral signatures, the multispectral approach, and the principal types of sensors and platforms used in remote sensing are also considered.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: The LANDSAT Tutorial Workbook; p 9-38
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  • 19
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    Publication Date: 2006-06-04
    Description: Operation of the microwave instrument as a two frequency scatterometer, a synthetic aperture radar, and a passive microwave radiometer is planned. Operation of the instrument in each of its three modes is discussed and the antenna system described.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: NASA. Marshall Space Flight Center Spacelab Mission 1 Expt. Descriptions; 3 p
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  • 20
    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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  • 21
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    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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  • 22
    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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  • 23
    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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  • 24
    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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  • 25
    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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  • 26
    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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  • 27
    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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  • 28
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    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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  • 29
    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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  • 30
    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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  • 31
    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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  • 32
    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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  • 33
    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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  • 34
    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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  • 35
    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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  • 36
    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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  • 37
    Publication Date: 2006-02-14
    Description: LANDSAT data acquired over an agricultural area along with ground enumeration of the same area are used to obtain crop acreage estimates which are better (as measured in terms of bias and variance) than can be obtained from either data source alone. Two basic approaches considered within the AgRISTARS program are a stratified crop acreage estimator and a regression estimator. A statement of the problem was mathematically formulated and some theorems were proved which relate to the variance of the two estimators. For a particular set of data, the regression and stratified estimators are compared in terms of certain easily computed parameters.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Houston Univ. The 1981 NASA ASEE Summer Fac. Fellowship Program, Vol. 2; 17 p
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  • 38
    Publication Date: 2006-02-14
    Description: The two body problem was analyzed with a specific drag model. The model treats drag as a force proportional to the vector velocity and inversely proportional to the distance to the center of attraction. The solution is expressed in terms of known functions and is of a simple and compact form. The time of flight is expressed as a quadrature in the true anomaly. The results are: (1) development of a vector differential equation which allows analysis of an infinite number of gravitational and drag models; and (2) obtaining the solution of a linear differential equation using the inverse method of laplace transforms.
    Keywords: AERODYNAMICS
    Type: Houston Univ. The 1981 NASA ASEE Summer Fac. Fellowship Program, Vol. 2; 22 p
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  • 39
    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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  • 40
    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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  • 41
    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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  • 42
    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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  • 43
    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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  • 44
    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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  • 45
    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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  • 46
    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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  • 47
    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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  • 48
    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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  • 49
    Publication Date: 2006-02-14
    Description: To determine the low speed performance characteristics of a representative high aspect ratio supercritical wing, two low speed jet transport models were fabricated. A 12-ft. span model was used for low Reynolds number tests in the Langley 4- by 7-Meter Tunnel and the second, a 7.5-ft. span model, was used for high Reynolds number tests in the Ames 12-foot Pressure Tunnel. A brief summary of the results of the tests of these two models is presented and comparisons are made between the data obtained on these two models and other similar models. Follow-on two and three dimensional research efforts related to the EET high-lift configurations are also presented and discussed.
    Keywords: AERODYNAMICS
    Type: Advan. Aerodyn.: Selected NASA Res.; p 55-77
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  • 50
    Publication Date: 2006-02-14
    Description: Highlight results are presented from subsonic and transonic pressure measurement studies conducted in the Langley Transonic Dynamics Tunnel on a supercritical wing model representative of an energy efficient transport design. Steady- and unsteady-pressure data were acquired on the upper and lower wing surface at an off-design Mach number of 0.60 and at the design Mach number of 0.78, for a Reynolds number of 2.2 x 10(6) (based on the wing average chord). The model configuration consisted of a sidewall-Mounted half-body fuselage and a semi-span wing with an aspect ratio of 10.76, a leading-edge sweepback angle of 28.8 degrees, and supercritical airfoil sections. The wing is instrumented with 252 static pressure orifices and 164 dynamic pressure gages. Model test variables included wing angle of attack, control-surface mean deflection angle, control-surface oscillating deflection angle and frequency, and phasing between oscillating leading-edge and trailing-edge controls when used together.
    Keywords: AERODYNAMICS
    Type: Advan. Aerodyn.: Selected NASA Res.; p 21-36
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  • 51
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    Publication Date: 2006-04-16
    Description: The history of remote sensing is reviewed and the scope and versatility of the several remote sensing systems already in orbit are discussed, especially those with sensors operating in other EM spectral modes. The multisensor approach is examined by interrelating LANDSAT observations with data from other satellite systems. The basic principles and practices underlying the use of thermal infrared and radar sensors are explored and the types of observations and interpretations emanating from the Nimbus, Heat Capacity Mapping Mission, and SEASAT programs are examined. Approved or proposed Earth resources oriented missions for the 1980's previewed include LANDSAT D, Stereosat, Gravsat, the French satellite SPOT-1, and multimission modular spacecraft launched from space shuttle. The pushbroom imager, the linear array pushbroom radiometer, the multispectral linear array, and the operational LANDSAT observing system, to be designed the LANDSAT-E series are also envisioned for this decade.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: The LANDSAT Tutorial Workbook; p 327-387
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  • 52
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    In:  CASI
    Publication Date: 2006-04-16
    Description: The use of computer aided classification of LANDSAT data in developing water quality plans for New Jersey watersheds is used to exemplify how a state natural resource management program benefits from satellite imagery. The transition of a research and development system into an operational remote sensing system to help decision makers is demonstrated. Nontechnial issues that can assist (or hinder) an agency in adopting a new technology are examined. The progress of LANDSAT use by state government from the earliest stage of curiosity through to incorporation in actual state planning methods is charted. Potential applications of LANDSAT data to real information needs and solutions to management problems are examined. The problems and mistakes that occurred in using LANDSAT data in the past are discussed as well as the ways by which these problems were overcome.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: The LANDSAT Tutorial Workbook; p 309-326
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  • 53
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    In:  CASI
    Publication Date: 2006-04-16
    Description: Information and activities are provided to: (1) enhance the ability to distinguish between a Geographic Information System (GIS) and a data management system; (2) develop understanding of spatial data handling by conventional methods versus the automated approach; (3) promote awareness of GIS design and capabilities; (4) foster understanding of the concepts and problems of data base development and management; (5) facilitate recognition of how a computerized GIS can model conditions in the present "real world" to project conditions in the future; and (6) appreciate the utility of integrating LANDSAT and other remotely sensed data into the GIS.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: The LANDSAT Tutorial Workbook; p 277-308
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  • 54
    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center, Theoretical Aerodynamics Contractors' Workshop, Volume 2; p 607-63
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  • 55
    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center, Theoretical Aerodynamics Contractors' Workshop, Volume 2; p 557-58
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  • 56
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center, Theoretical Aerodynamics Contractors' Workshop, Volume 2; p 539-55
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  • 57
    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center, Theoretical Aerodynamics Contractors' Workshop, Volume 2; p 461-49
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  • 58
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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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  • 59
    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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  • 60
    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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  • 61
    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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  • 62
    Publication Date: 2011-08-18
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 21; 809-815
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  • 63
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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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  • 64
    Publication Date: 2011-08-18
    Description: A multistage sampling procedure using image processing, geographical information systems, and analytical photogrammetry is presented which can be used to guide the collection of representative, high-resolution spectra and discrete reflectance targets for future satellite sensors. The procedure is general and can be adapted to characterize areas as small as minor watersheds and as large as multistate regions. Beginning with a user-determined study area, successive reductions in size and spectral variation are performed using image analysis techniques on data from the Multispectral Scanner, orbital and simulated Thematic Mapper, low altitude photography synchronized with the simulator, and associated digital data. An integrated image-based geographical information system supports processing requirements.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 65
    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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  • 66
    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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  • 67
    Publication Date: 2011-08-18
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 21; 700-707
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  • 68
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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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  • 69
    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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  • 70
    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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  • 71
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    In:  Other Sources
    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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  • 72
    Publication Date: 2011-08-18
    Description: A goal of future synthetic aperture radar (SAR) system design is to yield the radiometrically accurate imagery necessary for use in classification problems. To accomplish this, a reliable calibration technique must be developed. Many such techniques have been proposed (e.g., Stiles and Holtzman, 1982); however, until now, none have been tested on spaceborne SAR digital data. In this paper, a method of significantly increasing the reproducibility of several independent Seasat SAR data sets of a test site using an automated correction procedure is described.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 73
    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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  • 74
    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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  • 75
    Publication Date: 2011-08-18
    Description: The spectral and spatial requirements for remote sensing in the next decade are presented. The requirements presented were obtained through extensive literature research and discussions with leading members of the various remote sensing research communities. In the 0.35-2.5 micron region of the spectrum, numerous bands will be needed at bandwidths as narrow as 10-20 nanometers. There is also growing interest in the thermal infrared (8-14 microns). Spatial resolution (instantaneous field of view) of 5 to 10 meters will be of great benefit to many fields of remote sensing.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 76
    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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  • 77
    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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  • 78
    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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  • 79
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    In:  Other Sources
    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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  • 80
    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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  • 81
    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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  • 82
    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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  • 83
    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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  • 84
    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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  • 85
    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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  • 86
    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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  • 87
    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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  • 88
    facet.materialart.
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    In:  Other Sources
    Publication Date: 2011-08-18
    Description: The potential of planform modification and hinge-line relocation to improve the thrust efficiency of vortex flaps was experimentally investigated on a 60-deg cropped delta wing model. Spanwise segmentation of the flap, together with chord-tailoring of the segments, allowed the vortex to be maintained on the outboard flap surfaces to higher angles of attack. In addition, location of the flap hinge aft of and underneath the wing leading edge generated substantial thrust from the vortex suction acting on the leading-edge lower surface. A combination of these beneficial effects allowed the flap/wing area to be reduced from 11.4 percent of the continuous flap to 6.3 percent of segmented flap, essentially without detriment to the incremental lift-to-drag ratio due to flap addition in the lift coefficient range 0.5-0.7 based on the basic wing area.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 20; 1062-106
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  • 89
    Publication Date: 2011-08-18
    Description: Previously cited in issue 20, p. 3138, Accession no. A82-40893
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 20; 993-1006
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  • 90
    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 spectral 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. Previously announced in STAR as N82-25602
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  • 91
    Publication Date: 2011-08-18
    Description: Previously cited in issue 06, p. 799, Accession no. A82-17876
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 21; 1611-161
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  • 92
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    Publication Date: 2011-08-18
    Description: A complete automatic unsupervised classification approach has been developed to estimate the proportion of corn, soybeans, and other crops in a Landsat 5-by-6-nanometer segment. The technique involves extracting crop growth variables that are predictable from agromet models, it provides a signature extension not possible before. The technique has been applied in 3 years (1978-1980) for 56 segments and shows neither a year-to-year effect nor any geographic effect. The results to date are considered far better than those obtainable from any other currently available technique. Nontheless, the technique can be improved to reduce the bias.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 93
    Publication Date: 2011-08-18
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 94
    Publication Date: 2011-08-18
    Description: Since NASA's program of research concerning remote sensing was initiated in the 1960s, one of its major objectives has been to advance the state-of-the-art in machine processing of satellite acquired multispectral data. Possibilities have been studied regarding a use of these data to identify type, to monitor condition, and to estimate the ontogenetic stage of cultural vegetation. The present investigation provides a review of the state-of-the-art of the technology used to make remote sensing crop production estimates in foreign regions. Attention is given to Landsat data acquisition, aspects of registration and preprocessing, questions of data transformation, data modeling, proportion estimation, labeling, development stage models, crop condition models, and an outlook regarding future developments.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 95
    Publication Date: 2011-08-18
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 96
    Publication Date: 2011-08-18
    Description: The improved spatial resolution of the new earth resources satellites will increase the need for effective utilization of spatial information in machine processing of remotely sensed data. One promising technique is scene segmentation by region growing. Region growing can use spatial information in two ways: only spatially adjacent regions merge together, and merging criteria can be based on region-wide spatial features. A simple region growing approach is described in which the similarity criterion is based on region mean and variance (a simple spatial feature). An effective way to implement region growing for remote sensing is as an iterative parallel process on a large parallel processor. A straightforward parallel pixel-based implementation of the algorithm is explored and its efficiency is compared with sequential pixel-based, sequential region-based, and parallel region-based implementations. Experimental results from on aircraft scanner data set are presented, as is a discussioon of proposed improvements to the segmentation algorithm.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 97
    Publication Date: 2011-08-18
    Description: The scientific instruments comprising the OSTA-1 package flown on the second Shuttle mission (November 12-14, 1981) are listed, and the Shuttle Imaging Radar (SIR-A) experiments are examined in detail: SIR-A operated for 8 h and obtained images covering more than 10 million sq km at 40-m resolution. The images were recorded on photographic film and processed in holographic form at JPL, and data for Southern Europe and parts of Africa were distributed to French scientists by the Groupement pour le Developpement de la Teledetection Aerospatiale. The main areas of research were environmental studies and geology, and the SIR-A images were used in combination with aerial photography, thematic maps, and Landsat images. The technical specifications of the SIR-B radar planned for STS-17 in 1984 are compared with those of SIR-A and Seasat SAR in tables.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Societe Francaise de Photogrammetrie et de Teledetection, Bulletin (ISSN 0244-6014); 91, 1; 5-9
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  • 98
    Publication Date: 2011-08-18
    Description: The use of remote sensing in resource exploration is reviewed, with emphasis placed on new developments in high spectral resolution remote-sensing techniques for mineralogic and vegetation mapping. Topics discussed include aerial photography and satellite remote sensing, concepts and principles of spectral data collection, spectral properties of rocks and minerals, spectral properties of vegetation, and botanical aspects of geochemical stress. The discussion also covers applications of Landsat multispectral scanner data to lithologic and geobotanic studies and the future development of data acquisition and data interpretation techniques.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Economic Geology and Society of Economic Geologists, Bulletin (ISSN 0361-0128); 78; 573-590
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  • 99
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    Publication Date: 2011-08-18
    Description: A mesh system composed of multiple overset body-conforming grids is described for adapting finite-difference procedures to complex aircraft configurations. In this so-called 'chimera mesh,' a major grid is generated about a main component of the configuration and overset minor grids are used to resolve all other features. Methods for connecting overset multiple grids and modifications of flow-simulation algorithms are discussed. Computational tests in two dimensions indicate that the use of multiple overset grids can simplify the task of grid generation without an adverse effect on flow-field algorithms and computer code complexity.
    Keywords: AERODYNAMICS
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  • 100
    Publication Date: 2011-08-18
    Description: In this paper, results of a Monte Carlo simulation of the effect of noise on the relationship between the microwave emissivity of soil and its moisture content are presented. It is found that whenever the magnitude of the noise for the independent variable, in this case the soil moisture, is increased, both the slope of the regression and the correlation coefficient decrease. In particular, when the noise has magnitude equivalent to a coefficient of variation of 0.25, the slope and correlation coefficient are in good agreement with those obtained from the data of a 21-cm airborne microwave radiometer which was flown over a test site in hand county, South Dakota. The comparison was made using a linear relationship to determine the estimated emissivity from the ground measurements of soil moisture. The linear relationship was derived from a radiative transfer model calculation of the microwave emissivities using realistic soil-moisture profiles. The effect of surface roughness was included in the relationship, and the variability of the surface roughness was also simulated by a Monte Carlo technique.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: IEEE Transactions on Geoscience and Remote Sensing (ISSN 0196-2892); GE-21; 473-479
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