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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 253 records · Page 14
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NASA NTRS1991

Relationship between gas exchange, wind speed, and radar backscatter in a large wind-wave tank

The relationships between the gas exchange, wind speed, friction velocity, and radar backscatter from the water surface was investigated using data obtained in a large water tank in the Delft (Netherlands) wind-wave tunnel, filled with water supersaturated with SF6, N2O, and CH4. Results indicate that the gas-transfer velocities of these substances were related to the wind speed with a power law dependence. Microwave backscatter from water surface was found to be related to gas transfer velocities by a relationship in the form k(gas) = a 10 exp (b A0), where k is the gas transfer velocity for the particular gas, the values of a and b are obtained from a least squares fit of the average backscatter cross section and gas transfer at 80 m, and A0 is the directional (azimuthal) averaged return.

Wanninkhof, Richard H.↗
NASA NTRS1991

Airborne precursor missions in support of SIR-C/X-SAR

The NASA DC-8 and DLR E-SAR airborne imaging radars have been deployed over several sites in Europe and the U.S. in support of SIR-C/X-SAR (Shuttle Imaging Radar-C/X-Synthetic Aperture Radar) science team investigations. To date, data have been acquired in support of studies of alpine glaciers, forests, geology, oceanography, and calibration. An experimental campaign with airborne sensors will take place in Europe in June to July 1991 which will allow multitemporal surveys of several Europeans sites. Current plans are for calibration and ecology experiments to be undertaken in Germany, the Netherlands, Italy, France, and the United Kingdom. Coordinated multitemporal aircraft and ground campaigns are planned in support of hydrology experiments in Italy, the United Kingdom, and Austria. Data will also be acquired in support of oceanogrqhy in the Gulf of Genova, North Atlantic, Straits of Messina and the North Sea. Geology sites will include Campi Flegrei and Vesuvio, Italy.

Evans, D.↗
NASA NTRS1991

Multi-frequency and polarimetric radar backscatter signatures for discrimination between agricultural crops at the Flevoland experimental test site

We describe the calibration and analysis of multi-frequency, multi-polarization radar backscatter signatures over an agriculture test site in the Netherlands. The calibration procedure involved two stages: in the first stage, polarimetric and radiometric calibrations (ignoring noise) were carried out using square-base trihedral corner reflector signatures and some properties of the clutter background. In the second stage, a novel algorithm was used to estimate the noise level in the polarimetric data channels by using the measured signature of an idealized rough surface with Bragg scattering (the ocean in this case). This estimated noise level was then used to correct the measured backscatter signatures from the agriculture fields. We examine the significance of several key parameters extracted from the calibrated and noise-corrected backscatter signatures. The significance is assessed in terms of the ability to uniquely separate among classes from 13 different backscatter types selected from the test site data, including eleven different crops, one forest and one ocean area. Using the parameters with the highest separation for a given class, we use a hierarchical algorithm to classify the entire image. We find that many classes, including ocean, forest, potato, and beet, can be identified with high reliability, while the classes for which no single parameter exhibits sufficient separation have higher rates of misclassification. We expect that modified decision criteria involving simultaneous consideration of several parameters increase performance for these classes.

Freeman, A.↗
NASA NTRS1992

First Results from TROLIX 1991: an Intercomparison of Tropospheric Ozone Lidars

Within the framework of the European environmental research programme EUROTRAC, lidar systems for routine measurements of vertical ozone profiles throughout the planetary boundary layer and the free troposphere are currently under development. Several of these systems are now operational and an intercomparison experiment was undertaken in the period from June 10 to June 28, 1991 in Bilthoven, the Netherlands. The main scientific objectives defined for the campaign are: (1) compare the lidar measurements to in situ measurements of the ozone concentration; (2) determine how many and which wavelengths are needed for a sufficiently accurate ozone retrieval in the lower troposphere under realistic conditions; (3) assess the accuracy that can be achieved under realistic conditions; and (4) compare the performance of the participating systems.

Apituley, A.↗
NASA NTRS1992

Study of optical techniques for the Ames unitary wind tunnels. Part 3: Angle of attack

A review of optical sensors that are capable of accurate angle of attack measurements in wind tunnels was conducted. These include sensors being used or being developed at NASA Ames and Langley Research Centers, Boeing Airplane Company, McDonald Aircraft Company, Arnold Engineering Development Center, National Aerospace Laboratory of the Netherlands, National Research Council of Canada, and the Royal Aircraft Establishment of England. Some commercial sensors that may be applicable to accurate angle measurements were also reviewed. It was found that the optical sensor systems were based on interferometers, polarized light detector, linear or area photodiode cameras, position sensing photodetectors, and laser scanners. Several of the optical sensors can meet the requirements of the Ames Unitary Plan Wind Tunnel. Two of these, the Boeing interferometer and the Complere lateral effect photodiode sensors are being developed for the Ames Unitary Plan Wind Tunnel.

Lee, George↗
NASA NTRS1992

The design concept of the 6-degree-of-freedom hydraulic shaker at ESTEC

The European Space Agency (ESA) has decided to extend its test facilities at the European Space and Technology Center (ESTEC) at Noordwijk, The Netherlands, by implementing a 6-degree-of-freedom hydraulic shaker. This shaker will permit vibration testing of large payloads in the frequency range from 0.1 Hz to 100 Hz. Conventional single axis sine and random vibration modes can be applied without the need for a configuration change of the test set-up for vertical and lateral excitations. Transients occurring during launch and/or landing of space vehicles can be accurately simulated in 6-degrees-of-freedom. The performance requirements of the shaker are outlined and the results of the various trade-offs, which are investigated during the initial phase of the design and engineering program are provided. Finally, the resulting baseline concept and the anticipated implementation plan of the new test facility are presented.

Brinkman, P. W.↗
NASA NTRS1992

The JGOFS North Atlantic Bloom Experiment: An overview

The North Atlantic Bloom Experiment (NABE) of JGOFS presents a unique opportunity and challenge to the data management community because of the diversity and large size of biogeochemical data sets collected. NABE was a pilot study for JGOFS and has also served as a pilot study within the U.S. NODC for management and archiving of the data sets. Here I present an overview to some of the scientific results of NABE, which will be published as an Introduction to a special volume of NABE results in Deep-Sea Research later this year. An overview of NABE data management is given elsewhere in the present report. This is the first collection of papers from the Joint Global Ocean Flux Study (JGOFS). Formed as an international program in 1987, JGOFS has four principal elements: modelling and data management, multidisciplinary regional process studies, a global survey of biogeochemical properties and long-term time series observatories. In 1989-1990 JGOFS conducted a pilot process study of the spring phytoplankton bloom, the North Atlantic Bloom Experiment (NABE). JGOFS decided to conduct a large scale, internationally-coordinated pilot study in the North Atlantic because of its proximity to the founding nations of the project, the size and predictability of the bloom and its fundamental impact on ocean bio-geochemistry (Billett et al., 1983; Watson and Whitfield, 1985; Pfannkuche, 1992). In 1989, six research vessels from Canada, Germany, The Netherlands, the United Kingdom and the USA and over 200 scientists and students from more than a dozen nations participated in NABE. Some of their initial results are reported in this volume.

Ducklow, Hugh W.↗
NASA NTRS1993

An atlas of ultraviolet spectra of star-forming galaxies

A systematic study is presented of the UV spectra of star-forming galaxies of different morphological type and activity class using a sample drawn from a uniformly reduced IUE data set. The spectra for a wide variety of galaxies, including normal spiral, LINER, starburst, blue compact, blue compact dwarf, and Seyfert 2 galaxies, are presented in the form of spectral energy distributions to demonstrate the overall characteristics according to morphology and activity class and in the form of absolute flux distributions to better show the absorption and emission features of individual objects. The data support the picture based on UV spectra of the Orbiting Astronomical Observatory and of the Astronautical Netherlands Satellite that spiral galaxies of later Hubble class have more flux at the shortest UV wavelengths than do spiral galaxies of earlier Hubble class.

Kinney, A. L.↗
NASA NTRS1993

Performances of a date dissemination code on telephone lines using commercial modems

A coded time/date information dissemination system (CTD), based on telephone lines and commercial modems, is now in its experimental phase in Italy at IEN. This service, born from a cooperation with other metrological laboratories (TUG, Austria, SNT, Sweden, VSL, The Netherlands), represents an attempt towards an European standardization. Some results of an experimental analysis in which a few modems were tested, both in laboratory conditions and connected to the telephone network, in order to evaluate the timing capability of the system are given. When the system is used in a one-way mode, in many practical cases the modems delay turns out to be the main factor which limits the accuracy, even more than the telephone line delays. If the two-way mode is used, the modems asymmetry, i.e., the delay difference between transmission and reception, is almost always the most important source of uncertainty, provided the link is not including a space segment. Comparing the widely used V.22 modems to the old V.21 ones, the latters turn out to be better both in delay time (30-100 ms V.22, and 7-15 ms V.21) and asymmetry (10-50 micro-s V.22, and 10 ms V.22). Time transfer accuracies of 10 micron-s (same turn) to 100 micro-s (long distance calls) were obtained in two-way mode with commercial V.21 modems.

Cordara, F.↗
NASA NTRS1993

The International Colloquium on Atomic Spectra and Oscillator Strengths for Astrophysical and Laboratory Plasmas

This was the fourth in a series of colloquia begun at the University of Lund, Sweden in 1983 and subsequently held in Toledo, Ohio and Amsterdam, The Netherlands. The purpose of these meetings is to provide an international forum for communication between major users of atomic spectroscopic data and the providers of these data. These data include atomic wavelengths, line shapes, energy levels, lifetimes, and oscillator strengths. Speakers were selected from a wide variety of disciplines including astrophysics, laboratory plasma research, spectrochemistry, and theoretical and experimental atomic physics.

Sugar, J.↗
NASA NTRS1993

NASA/DOD Aerospace Knowledge Diffusion Research Project. Paper 33: Technical communications practices and the use of information technologies as reported by Dutch and US aerospace engineers

As part of Phase 4 of the NASA/DOD Aerospace Knowledge Diffusion Research Project, two studies were conducted that investigated the technical communications practices of Dutch and U.S. aerospace engineers and scientists. A self-administered questionnaire was distributed to aerospace engineers and scientists at the National Aerospace Laboratory (The Netherlands), and NASA ARC (U.S.), and NASA LaRC (U.S.). This paper presents responses of the Dutch and U.S. participants to selected questions concerning four of the seven project objectives: determining the importance of technical communications to aerospace engineering professionals, investigating the production of technical communications, examining the use and importance of computer and information technology, and exploring the use of electronic networks.

Barclay, Rebecca O.↗
NASA NTRS1992

Deep near-infrared survey of the Southern Sky (DENIS)

DENIS (Deep Near-Infrared Survey of the Southern Sky) will be the first complete census of astronomical sources in the near-infrared spectral range. The challenges of this novel survey are both scientific and technical. Phenomena radiating in the near-infrared range from brown dwarfs to galaxies in the early stages of cosmological evolution, the scientific exploitation of data relevant over such a wide range requires pooling expertise from several of the leading European astronomical centers. The technical challenges of a project which will provide an order of magnitude more sources than given by the IRAS space mission, and which will involve advanced data-handling and image-processing techniques, likewise require pooling of hardware and software resources, as well as of human expertise. The DENIS project team is composed of some 40 scientists, computer specialists, and engineers located in 5 European Community countries (France, Germany, Italy, The Netherlands, and Spain), with important contributions from specialists in Australia, Brazil, Chile, and Hungary. DENIS will survey the entire southern sky in 3 colors, namely in the I band at a wavelength of 0.8 micron, in the 1.25 micron J band, and in the 2.15 micron K' band. The sensitivity limits will be 18th magnitude in the I band, 16th in the J band, and 14.5th in the K' band. The angular resolution achieved will be 1 arcsecond in the I band, and 3.0 arcseconds in the J and K' bands. The European Southern Observatory 1 m telescope on La Silla will be dedicated to survey use during operations expected to last four years, commencing in late 1993. DENIS aims to provide the astronomical community with complete digitized infrared images of the full southern sky and a catalogue of extracted objects, both of the best quality and in readily accessible form. This will be achieved through dedicated software packages and specialized catalogues, and with assistance from the Leiden and Paris Data Analysis Centers. The data will be mailed on DAT tapes from La Silla to the two Data Analysis Centers for further processing. Two centers are necessary because of the shear quantity of data and because of the complementary roles the Centers will develop, each exploiting its own particular expertise. The Leiden Data Analysis Center (LDAC) will extract objects, establish their parameters, and archive them into a source catalogue. The LDAC will collaborate with the Groningen Space Research group that has gained experience in infrared image handling from the IRAS satellite. The Paris Data Analysis Center (PDAC) will be responsible for archiving and preprocessing the raw data to provide a homogeneous set of data suitable for further reduction in both the Leiden and Paris data analysis streams. The PDAC will also extract and archive images for the sources flagged by the LDAC as extended, and create a catalogue of galaxies. In exploiting the DENIS data we foresee the collaboration with other data analysis centers, such as the Observatoire de Lyon where the relevant DENIS catalogue of galaxies can be incorporated into their extragalactic database. The Point Sources and the Small Extended Sources catalogues could be incorporated in the Late Type Star database at Montpellier, and in the SIMBAD database as CDS. At Groningen the IRAS Point Source catalogue and/or image data can be merged with the DENIS catalogues. At Meudon algorithms and software will be developed with main goal assessing the limits reachable for the homogeneity and intrinsic consistency between the ensemble of the images in the data base (flat-fielding, relative positioning of the fields, bootstrapped flux calibration) but also for the data analysis.

Deul, E.↗
NASA NTRS1992

Programmability in AIPS++

AIPS++ is an Astronomical Information Processing System being designed and implemented by an international consortium of NRAO and six other radio astronomy institutions in Australia, India, the Netherlands, the United Kingdom, Canada, and the USA. AIPS++ is intended to replace the functionality of AIPS, to be more easily programmable, and will be implemented in C++ using object-oriented techniques. Programmability in AIPS++ is planned at three levels. The first level will be that of a command-line interpreter with characteristics similar to IDL and PV-Wave, but with an intensive set of operations appropriate to telescope data handling, image formation, and image processing. The third level will be in C++ with extensive use of class libraries for both basic operations and advanced applications. The third level will allow input and output of data between external FORTRAN programs and AIPS++ telescope and image databases. In addition to summarizing the above programmability characteristics, this talk will given an overview of the classes currently being designed for telescope data calibration and editing, image formation, and the 'toolkit' of mathematical 'objects' that will perform most of the processing in AIPS++.

Hjellming, R. M.↗
NASA NTRS1992

The EXOSAT database and archive

The EXOSAT database provides on-line access to the results and data products (spectra, images, and lightcurves) from the EXOSAT mission as well as access to data and logs from a number of other missions (such as EINSTEIN, COS-B, ROSAT, and IRAS). In addition, a number of familiar optical, infrared, and x ray catalogs, including the Hubble Space Telescope (HST) guide star catalog are available. The complete database is located at the EXOSAT observatory at ESTEC in the Netherlands and is accessible remotely via a captive account. The database management system was specifically developed to efficiently access the database and to allow the user to perform statistical studies on large samples of astronomical objects as well as to retrieve scientific and bibliographic information on single sources. The system was designed to be mission independent and includes timing, image processing, and spectral analysis packages as well as software to allow the easy transfer of analysis results and products to the user's own institute. The archive at ESTEC comprises a subset of the EXOSAT observations, stored on magnetic tape. Observations of particular interest were copied in compressed format to an optical jukebox, allowing users to retrieve and analyze selected raw data entirely from their terminals. Such analysis may be necessary if the user's needs are not accommodated by the products contained in the database (in terms of time resolution, spectral range, and the finesse of the background subtraction, for instance). Long-term archiving of the full final observation data is taking place at ESRIN in Italy as part of the ESIS program, again using optical media, and ESRIN have now assumed responsibility for distributing the data to the community. Tests showed that raw observational data (typically several tens of megabytes for a single target) can be transferred via the existing networks in reasonable time.

Reynolds, A. P.↗
NASA NTRS1993

Integrating payload design, planning, and control in the Dutch Utilisation Centre

Spacecraft payload design, experiment planning and scheduling, and payload control are traditionally separate areas of activity. This paper describes the development of a prototype software tool--the Activity Scheduling System (ASS)--which integrates these activity areas. ASS is part of a larger project to build a Dutch Utilisation Centre (DUC), intended eventually to support all space utilization activities in The Netherlands. ASS has been tested on the High Performance Capillary Electrophoresis payload. The paper outlines the integrated preparation and operations concept embodied in ASS. It describes the ASS prototype, including a typical session. The results of testing are summarized. Possible enhancement of ASS, including integration into DUC, is sketched.

Grant, T. J.↗
NASA NTRS1993

Test of prototype liquid-water-content meter for aircraft use

This report describes the effort undertaken to meet the objectives of National Science Foundation Grant ATM-9207345 titled 'Test of Prototype Liquid-Water-Content Meter for Aircraft Use.' Three activities were proposed for testing the new aircraft instrument, PVM-100A: (1) Calibrate the PVM-100A in a facility where the liquid-water-content (LWC) channel, and the integrated surface area channel (PSA) could be compared to standard means for LWC and PSA measurements. Scaling constant for the channels were to be determined in this facility. The fog/wind tunnel at ECN, Petten, The Netherlands was judged the most suitable facility for this effort. (2) Expose the PVM-100A to high wind speeds similar to those expected on research aircraft, and test the anti-icing heaters on the PVM-100A under typical icing conditions expected in atmospheric clouds. The high-speed icing tunnel at NRC, Ottawa, Canada was to be utilized. (3) Operate the PVM-100A on an aircraft during cloud penetrations to determine its stability and practicality for such measurements. The C-131A aircraft of the University of Washington was the aircraft of opportunity for these-tests, which were to be conducted during the 4-week Atlantic Stratocumulus Transition Experiment (ASTEX) in June of 1992.

Gerber, Hermann E.↗
NASA NTRS1994

NASA/DOD Aerospace Knowledge Diffusion Research Project. Paper 41: Technical communication practices of Dutch and US aerospace engineers and scientists: International perspective on aerospace

As part of Phase 4 of the NASA/DOD Aerospace Knowledge Diffusion Research Project, studies were conducted that investigated the technical communications practices of Dutch and U.S. aerospace engineers and scientists. The studies had the following objectives: (1) to solicit the opinions of aerospace engineers and scientists regarding the importance of technical communication to their professions, (2) to determine the use and production of technical communication by aerospace engineers and scientists, (3) to investigate their use of libraries and technical information centers, (4) to investigate their use of and the importance to them of computer and information technology, (5) to examine their use of electronic networks, and (6) to determine their use of foreign and domestically produced technical reports. Self-administered (mail) questionnaires were distributed to Dutch aerospace engineers and scientists at the National Aerospace Laboratory (NLR) in the Netherlands, the NASA Ames Research Center in the U.S., and the NASA Langley Research Center in the U.S. Responses of the Dutch and U.S. participants to selected questions are presented in this paper.

Barclay, Rebecca O.↗
NASA NTRS1993

NASA/DoD Aerospace Knowledge Diffusion Research Project. XXXIII - Technical communications practices and the use of information technologies as reported by Dutch and U.S. aerospace engineers

As part of Phase 4 of the NASA/DOD Aerospace Knowledge Diffusion Research Project, two studies were conducted that investigated the technical communications practices of Dutch and U.S. aerospace engineers and scientists. A self-administered questionnaire was distributed to aerospace engineers and scientists at the National Aerospace Laboratory (The Netherlands), and NASA Ames Research Center (U.S.), and the NASA Langley Research Center (U.S.). This paper presents responses of the Dutch and U.S. participants to selected questions about four of the seven project objectives: determining the importance of technical communications to aerospace engineering professionals, investigating the production of technical communications, examining the use and importance of computer and information technology, and exploring the use of electronic networks.

Barclay, Rebecca O.↗