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coordination with other governmental organizations in areas of mutual interest.
oscillation. An experimental implementation of the control strategy using an open-loop, single axis torque that is shaped for simultaneous damping of the horizontal and vertical vibrations is described. The experimental control strategy demonstrates more than 99 percent reduction in the coupled residual vibrations.
N89-28036*# National Aeronautics and Space Administration.
A thermodynamically admissible theory of viscoplasticity with two internal variables (a back stress and a drag strength) is presented. Six material functions characterize a specific viscoplastic model. In the pursuit of compromise between accuracy and simplicity, a model is developed that is a hybrid of two existing viscoplastic models. A limited number of applications of the model to Al, Cu, and Ni are presented. A novel implicit integration method is also discussed. Applications are made to obtain solutions using this viscoplastic model.
N89-28040# New Jersey Inst. of Tech., Newark. Office of
N89-28037# Institut National Polytechnique, Grenoble (France).
The behavior of mild steel and pure copper thin plates under sequential loading is studied. A macroscopic model is developed and a Hill criterion is identified to define a mode and a predeformation rate in agreement with the experimental results. The copper anisotropic macroscopic model does not describe correctly the behavior found in experiments. Further development of the presented models is discussed.
(Grant AF-AFOSR-0182-88; AF Proj. 2304) (AD-A208589; AFOSR-89-0723TR) Avail: NTIS HC A02/MF A01 CSCL 07/4
The deformation of granular materials occurs in a variety of applications: soil dynamics; avalanch flows; and grain flow in bins. The goal in this project is to develop a more complete understanding of the mechanics of granular flow. The project consists of two distinct but related phases. One phase is a study of the mathematical structure of constitutive relations used to model the granular medium. The research here is primarily concerned with the stability and well posedness of the evolution equations governing flow. Most of the efforts have concentrated on the Critical State Theory of Soil Mechanics, a mathematically attractive theory which has some success in modeling soil deformations. In particular, the Critical State Theory is reasonably successful at modeling the deformation of so called Cam clay, a type of clay tested by the Cambridge soil mechanics group in the late 1950's.
N89-28038# Sandia National Labs., Albuquerque, NM.
A limited number of step-by-step procedures were developed to recursively evaluate the response moments of uncertain systems. In several of these procedures, the recursive evaluation depends on discrete enforcement of a Gaussian approximation to the displacement and velocity response random processes. The error associated with such an approximation is isolated for a simple system using an analytic method which is not itself approximate in the manner of perturbation or Monte Carlo approaches. DOE
N89-28041# Carnegie-Mellon Univ., Pittsburgh, PA. NON-LINEAR DYNAMICS AND CHAOTIC MOTIONS IN FEEDBACK CONTROLLED ELASTIC SYSTEM Final Report, 1 Dec. 1983 - 30 Sep. 1988 1988 9p (Grant AF-AFOSR-0051-84; AF Proj. 2304) (AD-A208628; AFOSR-89-0725TR) Avail: NTIS HC A02/MF A01 CSCL 20/11
Work was continued on the global dynamics and bifurcations of O(2) symmetric ODEs. Such systems are obtained as finite dimensional projections or reductions of spatially translation- and reflection-invariant PDE S, for example. In 1987/88, partially supported by this grant, a complete analysis was provided for the heteroclinic cycles and modulated travelling waves in two mode (k:2K) interacting systems. In particular, it was pointed out that heteroclinic cycles are structurally stable features in such systems.
N89-28039# Sandia National Labs., Albuquerque, NM. MODEL BASED DAMPING OF COUPLED HORIZONTAL AND VERTICAL OSCILLATIONS IN A FLEXIBLE ROD B. J. Petterson and R. D. Robinett 1989 24 p Presented at the Guidance, Navigation, and Control Conference, Boston, MA, 14 Aug. 1989 (Contract DE-AC04-76DP-00789) (DE89-007034; SAND-88-2876C; CONF-890818-3) Avail: NTIS HC A03/MF A01
The theory associated with vibrations of angularly accelerated cantilevered beams which display significant gravitational sag (coupling the out-of-plane dynamics of the flexible beam) is reviewed and a control approach is formulated for moving such beams to damp residual first horizontal and vertical modes of
N89-28042# Georgetown Univ., Washington, DC. Dept. of
The principal achievement of the research undertaken under this grant was the development of comprehensive theories of exact controllability and stabilization of thin plate dynamics by means of forces and moments applied on the edge of the plate, based on continuum models of plates. Two major research monographs, which lay the foundations of the theories, were written. The motivation for this study, and its ultimate goal, is the design and analysis of practical strategies for active control and vibration suppression in flexible structures. A second, related, area of research was the design of feedback controls acting on the edge of the plate which uniformly stabilize plate motion, i.e, which cause all of the modes to decay at some uniform rate. Once again, such control strategies were sought for a wide variety of plate models, including nonlinear models. In fact, our results for nonlinear models (in which the nonlinearities may be both in the dynamics and in the feedback control) are probably the first of their kind.
An optical technique for measuring the Crack-Tip Opening Displacement (CTOD) of pre-cracked three-point bend specimens subjected to impact loading was developed. Procedures for computing a dynamic Load-STOD plot were also developed; this enables one to determine the dynamic fracture toughness. Finite element analyses were used to verity and extend the procedures.
42 GEOSCIENCES (GENERAL)
No abstracts in this category.
N89-28043# Rhode Island Univ., Kingston. Solid Mechanics
This report is concerned with the description of the development and application of a stochastic crack growth model. It is built as a discontinuous Markov process and is inhomogeneous with respect to the number of cycles required for the crack to reach a specified crack length. The model is then used to describe the evolution of the crack length in terms of growth curves, each of whose points possess equal probability of advancing from one position to another forward position. The validity of the model is established by applying it to constant as well as to variable amplitude loading. In those applications the theoretical constant probability crack growth curves generated by the model compared to those experimentally obtained using Al 7075-T6 and Al 2024-T3 material for constant-amplitude loading while Ti-6A1-4V was used in single overload application. Results of these comparisons indicate the ability of the proposed model when fitted with parameters whose values can be obtained from a limited numbers of experimental tests, to predict the crack growth statistics under different loading conditions.
43 EARTH RESOURCES AND REMOTE
Includes remote sensing of earth resources by aircraft and spacecraft; photogrammetry; and aerial photography.
For instrumentation see 35 Instrumentation and Photography.
N89-28044# Materials Research Labs., Ascot Vale (Australia).
A finite element technique has been used to determine the stress intensity at the tip of a bore crack in a cylindrical fracture specimen. This technical note describes the detailed input for the computer programs which perform the stress analyses. Much of the preparatory work involves generating a suitable mesh of elements which represents the elastic properties of the specimen. The constraints which are imposed on the mesh geometry are described.
N89-28047*# State Univ. of New York, Binghamton. Dept. of
Original contains color illustrations (Contract NAS5-28738) (NASA-CR-183440; NAS 1.26:183440) Avail: NTIS HC A01/MF A01 CSCL 08B
The East Greenland Tertiary Igneous Province contains a variety of intrusive and extrusive rock types. The Skaergaard complex is the most well known of the intrusive centers. Landsat thematic mapping (TM) was used in conjunction with field spectrometer data to map these mafic intrusions. These intrusions are of interest as possible precious metal ore deposits. They are spectrally distinct from the surrounding Precambrian gneisses. However, subpixel contamination by snow, oxide surface coatings, lichen cover and severe topography limit the discrimination of lithologic units within the gabbro. Imagery of the Skaergaard and surrounding vicinity, and image processing and enhancement techniques are presented. Student theses and other publications resulting from this work are also listed.
N89-28045# Naval Research Lab., Washington, DC. Physical
Time-harmonic scattering and radiation by an elastic body into an inviscid fluid is studied as a problem of limiting amplitude. By supposing that all is known about the exterior Neumann-radiation problem and a certain interior traction eigenvalue problem, the interface problem is reduced to an interior one with a nonlocal boundary condition, which is shown to be well-posed in weak sense, modulo the satisfaction of a solvability condition. The convergence of a solution-approximating Galerkin procedure is established. It is shown that the acoustic field can be computed without examining the mentioned eigenvalue problem. GRA
N89-28048# Instituto de Pesquisas Espaciais, Sao Jose dos
The radiance arriving to a remote sensing satellite depends on the target illumination and reflection, and on the angles between: the terrain normal and the illuminating source, and the satellite sensor. For reforestations in mountainous regions the illumination angles are a prime factor. It is assumed that the forest reflection is Lambertian. The inclinations were obtained from a Digital Elevation Model of the area. The LANDSAT TM channels used were 3, 4 and 5, and the region was classified taking and not
N89-28046# Johns Hopkins Univ., Baltimore, MD. Dept. of
taking into account the terrain relief effect. A maximum likelihood classification has shown better results in the corrected image.
is to be validated for future crop seasons. Nevertheless it provided objective and accurate results for wheat estimation on the two crop seasons analyzed.
N89-28049# Instituto de Pesquisas Espaciais, Sao Jose dos
Presented at the 5th Brazilian Symposium on Remote Sensing, Natal, RN, 11-15 Oct. 1988 (INPE-4769-PRE/1438) Avail: NTIS HC A02/MF A01
As the map is a reduced representation of the topographic surface, the scale of the map determines the amount of information which can be shown. The consequence of scale reduction is generalization: the smaller the scale the greater the degree of generalization. An automatic solution is proposed based on the Mathematical Morphology operations of erosion and dilation. Using the SITIM, INPE's image processing system, an example of automatic scale reduction from 1:50,000 to 1:250,000 of a portion of Ilha Grande (RJ) is presented and compared to the existing topographic map.
N89-28052# Montana State Univ., Bozeman. Dept. of C/AE.
The thermomechanical properties of snow have been described in terms of microstructural processes. The constitutive theory was formulated in a form consistent with the second law of thermodynamics. The deformation was described in terms of such microstructural processes as pressure sintering, shearing deformations within the necks connecting the ice grains, and intergranular glide. The matrix material (ice) was modeled as an elastic-viscoplastic material such that transient response as well as steady state response to loading can be described. The formulation also has the ability to describe the development of material anisotropy which evolves as a result of sustained deformation. In conjunction with this, an experimental technique was developed to enable one to measure the change in the microstructure of the material due to deformation. This had to be done in order to determine if the constitutive theory was correctly describing the microstructural deformation processes. This technique involved the use of an image analysis system to quantitatively determine the important microstructural processes (grain size, pore size, neck length, bond radius, bonds/grain). Computer software had to be developed in order to automate the process as much as possible. Finally the changes in microstructure due to thermal effects were studied.
N89-28050# Instituto de Pesquisas Espaciais, Sao Jose dos Campos (Brazil). THE USE OF EDGE DETECTORS BASED ON MATHEMATICAL MORPHOLOGY IN REMOTE SENSING IMAGERY Erivaldo A. da Silva and Nelson D. A. Mascarenhas Dec. 1988 11 p In PORTUGUESE; ENGLISH summary Presented at the 5th Brazilian Symposium on Remote Sensing, Brazil, 11-15 Oct. 1988 (INPE-4777-PRE/1446) Avail: NTIS HC A03/MF A01
The edge detection problem has great importance in digital image processing. A large number of such detectors have been proposed in the literature. Recently, the theory of mathematical morphology was used as the basis for the proposal of new edge detectors. This work tests the use of one of these detectors on LANDSAT TM satellite images and compares its performance with a detector based on a digital approximation of the gradient.
N89-28053# Massachusetts Inst. of Tech., Cambridge. Marine
Presented at the MIT/Marine Industry Colleguim, Cambridge, MA, 9 Mar. 1989 (Grant NOAA-NA86AA-D-SG089) (PB89-187330; MITSG-89-3; OPPORTUNITY BRIEF-53) Avail: NTIS HC A03/MF A01 CSCL 08C
The presentations included in the workshop are: Acquisition of environmental satellite data; NOAA satellite data availability; intelligent browsing of image data; data assimilation studies with models of ocean circulation; industry data needs through the 1990s and beyond; and remarks on future satellite and data systems.
N89-28051# Instituto de Pesquisas Espaciais, Sao Jose dos
Wheat plays an important role in the Brazilian commodity production. Therefore, objective and reliable methods for yield estimation are needed, especially at the farm level where several management actions have to be taken. LANDSAT TM and agrometeorological data were integrated in order to obtain a model for wheat yield estimation at the farm level for a test site in the southwest of Sao Paulo State. LANDSAT data for the crop years of 1986 (three acquisitions) and 1987 (two acquisitions), agronomic and meteorological data were related to yield estimates at the field level (250 fields, approximately). Results have shown that vegetation index derived from LANDSAT TM explained 64 and 46 percent of wheat yield variability for the two crop year analyzed. The joint use of both vegetation index and agrometeorological data in a single model improved the results to 71 and 53 percent, respectively, for the crop year of 86 and 87. The proposed model
N89-28054# Los Alamos National Lab., NM.
Presented at the 1st Geospace Environment Modeling (GEM) Workshop, San Diego, CA, 19-21 Feb. 1989 (Contract NAG5-536; NAGW-1663; W-7405-eng-36) (DE89-012620; LA-UR-89-1595; CONF-8902115-1) Avail: NTIS HC A03/MF A01
Recent multi-spacecraft observations of the magnetopause have allowed us to establish its structure and dynamical behavior. The magnetopause current sheet is thicker than expected, often ten magnetosheath ion gyroradii or more. One very important result has been the confirmation of magnetic reconnection in both its quasi-steady and transient forms. A boundary layer of magnetosheath-like plasma is often, but not always, observed earthward of the magnetopause current layer. There is considerable small-scale magnetic structure within the current layer, suggesting the presence of filamentary currents much smaller than an ion gyroradius. Such micro-structure may be important in particle diffusion and, hence, reconnection. There are many outstanding questions, among them: How does the low latitude boundary layer form. Why is the magnetopause current layer so thick. What is the detailed structure and topology of FTEs. How are quasi-steady and transient reconnection related. The GEM program may help us address these issues.
N89-28055# European Space Agency, Paris (France).
In 1985 Earthnet decided to promote the use of the Thematic Mapper in Europe. A considerable volume of data received was made available to the user community to stimulate a wide range of projects. The results presented at the workshop refer to subjects which include snow cover, hydrology, coastal waters, geology, land use, forestry and cartography. For individual titles, see N89-28056 through N89-28091.
the Earth's Environment. A Pilot Project Campaign on LANDSAT Thematic Mapper Applications (1985-1987) May 1989 P 25-31 (For primary document see N89-28055 22-43) Copyright Avail: NTIS HC A15/MF A01; ESA Publications Div., ESTEC, Noordwijk, Netherlands, 80 Dutch guilders or 40 US dollars
The utility of TM data with its increased number of narrower spectral bands and better spatial resolution is investigated to see whether this data is more suitable for water quality monitoring purposes. The software system used to extract lake statistics from TM data is described. Cluster analysis and Monte Carlo simulation techniques were used. In general, clusters correspond to various lake trophic states, indicating that TM data is capable of separating such characteristics. Some anomalies were noted and are discussed. Different regression curves should be used for different lake types, with clustering used to determine these groups. ESA
N89-28056# Innsbruck Univ. (Austria). Inst. fuer Meteorologie
May 1989 P 3-12 Sponsored by the Austrian Fonds zur Foerderung der Wissenschaftlichen Forschung and the Oesterreichische Akademie der Wissenschaften, Vienna, Austria Original contains color illustrations (For primary document see N89-28055 22-43) Copyright Avail: NTIS HC A15/MF A01; ESA Publications Div., ESTEC, Noordwijk, Netherlands, 80 Dutch guilders or 40 US dollars
The significance of the improved spectral and spatial capabilities of the LANDSAT Thematic Mapper (TM) are investigated. Digital methods are applied for snow mapping in two drainage basins of the Austrian Alps using spectral ratios of the TM bands 3 and 5 for the compensation of topographic effects. An algorithm is developed for estimating the snow extent in partly cloud covered scenes, based on the altitude distribution of the different surface classes in the cloud free areas. LANDSAT TM is found an excellent tool for snow mapping in Alpine drainage basins and for investigations of snow and ice areas on Alpine glaciers. ESA
N89-28059# Muenster Univ. (Germany, F.R.). Dept. of
Original contains color illustrations (For primary document see N89-28055 22-43) Copyright Avail: NTIS HC A15/MF A01; ESA Publications Div., ESTEC, Noordwijk, Netherlands, 80 Dutch guilders or 40 US dollars
A hydrological model for estimating flood hydrographs in all subcatchments of a larger river basin is developed based on a spatial disaggregation approach. LANDSAT 5 TM data are used for a spatially detailed land use classification as an essential input of the module, which transforms rainfall to direct runoff. A rough distinction between forest types, land types, impervious and water areas is sufficient for runoff estimation. The results are presented as chorological runoff maps for several components and different levels of spatial resolution in the upper Lenne basin. ESA
N89-28057# Gesellschaft fuer Angewandte Fernerkundung, Munich (Germany, F.R.). MULTITEMPORAL SNOW CLASSIFICATION WITH TM DATA Ute Gangkofner In ESA, European Coordinated Effort for Monitoring the Earth's Environment. A Pilot Project Campaign on LANDSAT Thematic Mapper Applications (1985-1987) May 1989 p 13-21 Original contains color illustrations (For primary document see N89-28055 22-43) Copyright Avail: NTIS HC A15/MF A01; ESA Publications Div., ESTEC, Noordwijk, Netherlands, 80 Dutch guilders or 40 US dollars
The areal extent of snow cover in an region of Austrian Alps is determined on TM images from April to July 1984, by means of supervised maximum likelihood classification. Interpretation is severely restricted by saturation: TM1 totally saturates over snow; TM2 and TM3 largely, and even TM4 saturates to some extent. Besides snow mapping, the major vegetation types in the July image are classified. TM band 5 proves to be of major importance not only for snow cloud discrimination, but also for differentiation within the snow covered area and the vegetation types. ESA
N89-28060# Instituut voor Culturrtechniek en Waterhuishouding, Wageningen (Netherlands). APPLICATION OF REMOTE SENSING TO IRRIGATION WATER MANAGEMENT IN TWO ITALIAN IRRIGATION DISTRICTS S. Azzali and M. Menenti In ESA, European Coordinated Effort for Monitoring the Earth’s Environment. A Pilot Project Campaign on LANDSAT Thematic Mapper Applications (1985-1987) May 1989 p 41-48 Original contains color illustrations (For primary document see N89-28055 22-43) Copyright Avail: NTIS HC A15/MF A01; ESA Publications Div., ESTEC, Noordwijk, Netherlands, 80 Dutch guilders or 40 US dollars
The feasibility of a remote sensing method to determine quantity, type, and water shortage (water stress) of crops by means of LANDSAT TM images is demonstrated in two irrigation districts in the Po valley. It is shown that an accurate crop calendar applying for each area is required for the multitemporal analysis to be successful. Reflectance measurements in bands 3, 4, 5, and 7 are more reliable than estimates of surface temperature with band 6 measurements in detecting shortage of water availabili in crops.
N89-28058# University Coll., Dublin (Ireland). Dept. of Computer
N89-28061# Centro de Estudios y Experimentacion de Obras
of classes defined in a nearby control area. Visible channels are found more useful for studying the spreading of the suspended sediments.
Div., ESTEC, Noordwijk, Netherlands, 80 Dutch guilders or 40 US dollars
Evaluation and mapping of surface limnological variables in reservoirs is made on a single date basis by making use of LANDSAT 5 TM imagery. The variables used are water temperature, chlorophyll concentration and Secchi depth transparency. In total eight images/dates are included in the study involving up to eleven reservoirs. Reliable maps of chlorophyll and Secchi depth transparency are developed in most instances.
N89-28062# Geneva Univ. (Switzerland). Dept. of Geology.
Chromaticity transforms based on bands 1, 2, and 3 are computed for over 50 inland water bodies located in western Switzerland and southeastern France. Their trophic state varies between oligotrophic and eutrophic. In chomaticity space, the range from green blue, moderately saturated (clear water) to green, less saturated (high chlorophyll). A third pole is located towards isoradiance point (high mineral turbidity). Targets with bottom signal influence plot in between. It is shown that color transforms yield more information on water bodies typology and features than principal component analysis based on band radiances. ESA
N89-28065# Trinity Coll., Dublin (Ireland). THE USE OF THEMATIC MAPPER IMAGERY FOR PEATLAND MAPPING AND MINERAL EXPLORATION IN IRELAND G. W. Horgan and M. F. Critchley In ESA, European Coordinated Effort for Monitoring the Earth's Environment. A Pilot Project Campaign on LANDSAT Thematic Mapper Applications (1985-1987) May 1989 p 91-97 Original contains color illustrations (For primary document see N89-28055 22-43) Copyright Avail: NTIS HC A15/MF A01; ESA Publications Div., ESTEC, Noordwijk, Netherlands, 80 Dutch guilders or 40 US dollars
A two stage approach is used in the mapping of peatlands. Techniques base upon mathematical morphology are used to separate peatlands from other types of land cover. Maximum likelihood methods are then used to classify different types of peatlands. Using these methods it was possible to distinguish between areas of undisturbed, machine cut, hand cut, and burnt peat. Edge enhanced and directionally filtered band 4 imagery is used in mineral exploration to map geological structures. Statistical pattern analysis is found a useful method for this case. TM imagery is however hindered by agricultural features.
N89-28063# University Coll., Dublin (Ireland). Dept. of
The use of satellite imagery in the context of a proposed water quality management plan is considered. A synoptic appreciation of the heterogeneity of the Dublin Bay water body is obtained. The results, based on the reflectance patterns, generally reinforce the limited published hydrological data and the known behavior of point discharges, but suggets that the complexity of the dispersion processes is greater than that hitherto observed.
N89-28066# Freie Univ., Berlin (Germany, F.R.). Inst. of Applied Geology. LANDSAT TM STUDY OF SABKHA SURFACES IN THE QATTARA DEPRESSION, NORTHWESTERN EGYPT Frank K. List, Doris Linne, and Bernd Meissner In ESA, European Coordinated Effort for Monitoring the Earth's Environment. A Pilot Project Campaign on LANDSAT Thematic Mapper Applications (1985-1987) May 1989 p 99-110 Sponsored by the Deutsche Forschungsgeimschaft, Bonn, Fed. Republic of Germany Original contains color illustrations (For primary document see N89-28055 22-43) Copyright Avail: NTIS HC A15/MF A01; ESA Publications Div., ESTEC, Noordwijk, Netherlands, 80 Dutch guilders or 40 US dollars
A digital LANDSAT TM scene of January 1986 was studied in detail for a better discrimination of the different types of sabkha surfaces. Several combinations of spectral bands were examined in order to find out what type of color composite imagery would be best suited to visual interpretation. The digital classification by a maximum likelihood classifier, though rendering more detailed discrimination of the sabkha surfaces than visual interpretation alone, represents only an intermediary stage in the information extraction process.
N89-28064# Norwegian Hydrodynamic Labs., Trondheim.
The spreading of suspended sediments discharged from rivers into fjords are studied using visible and infrared TM data. Different methods are used to study the distribution of the surface turbidity and temperature. The color coding of brightness levels from channels 1, 2, and 3 seem to give the best resolution. Supervised classification techniques are useful in determining the presence
N89-28067# Karlsruhe Univ. (Germany, F.R.). Dept. of Photogrammetry and Remote Sensing. IMAGE PROCESSING STRATEGIES FOR MINERAL EXPLORATION IN ARID AREAS BY USE OF TM DATA H. Kaufmann in ESA, European Coordinated Effort for Monitoring the Earth's Environment. A Pilot Project Campaign on LANDSAT Thematic Mapper Applications (1985-1987) May 1989 p 111-125 Original contains color illustrations (For primary document see N89-28055 22-43) Copyright Avail: NTIS HC A15/MF A01; ESA Publications Div., ESTEC, Noordwijk, Netherlands, 80 Dutch guilders or 40 US dollars
Investigations were carried out in the Wadi Araba to trace the relationship between diagnostic signals received from LANDSAT TM data and several mineralized ground districts. Rationing, principal component analysis, and IHS decorrelation processing are used to enhance diagnostic features associated with hydrothermally altered areas. The ratio and PC approaches often fail to clearly discriminate between the diagnostic features. The main reasons are attributed to similarities in relative intensities of vegetation and minerals and to disadvantages that arise through the techniques themselves.