SEARCH · Search NASA

Results for “cover complexity”

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.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7

All sources NASA NTRS DOE OSTI

NASA NTRS1991

The 3rd Annual Controlled Structures Technology Symposium

Viewgraphs of presentations at the Controlled Structures Technology (CST) MIT Space Engineering Research Center 3rd Annual Symposium are included. Topics covered include optical interferometer testbed; active impedence matching of complex structural systems; application of CST to adaptive optics; middeck 0-G dynamics Experiment (MODE); inhibiting multiple mode vibration in controlled flexible systems; the middeck active control experiment (MACE); robust control for uncertain structures; cost averaging techniques for robust structural control; and intelligent structures technology.

Source record↗

NASA NTRS2003

Tensegrity I. Cell structure and hierarchical systems biology

In 1993, a Commentary in this journal described how a simple mechanical model of cell structure based on tensegrity architecture can help to explain how cell shape, movement and cytoskeletal mechanics are controlled, as well as how cells sense and respond to mechanical forces (J. Cell Sci. 104, 613-627). The cellular tensegrity model can now be revisited and placed in context of new advances in our understanding of cell structure, biological networks and mechanoregulation that have been made over the past decade. Recent work provides strong evidence to support the use of tensegrity by cells, and mathematical formulations of the model predict many aspects of cell behavior. In addition, development of the tensegrity theory and its translation into mathematical terms are beginning to allow us to define the relationship between mechanics and biochemistry at the molecular level and to attack the larger problem of biological complexity. Part I of this two-part article covers the evidence for cellular tensegrity at the molecular level and describes how this building system may provide a structural basis for the hierarchical organization of living systems--from molecule to organism. Part II, which focuses on how these structural networks influence information processing networks, appears in the next issue.

NASA Program Fundamental Space Biology↗

NASA NTRS1976

Development of explosive welding procedures to fabricate channeled nozzle structures

Research was conducted to demonstrate the feasibility of fabricating a large contoured structure with complex internal channeling by explosive welding procedures. Structures or nozzles of this nature for wind tunnel applications were designed. Such nozzles vary widely in their complexity. However, in their simplest form, they consist of a grooved base section to which a cover sheet is attached to form a series of internal cooling passages. The cover sheet attachment can be accomplished in various ways: fusion welding, brazing, and diffusion welding. The cover sheet has also been electroformed in place. Of these fabrication methods, brazing has proved most successful in producing nozzles with complex contoured surfaces and a multiplicity of internal channels.

Pattee, H. E.↗

NASA NTRS1995

The origin of the solar wind

The high speed solar wind, which is associated with coronal holes and unipolar interplanetary magnetic field, has now been observed in situ beyond 0.3 a.u. and at latitudes up to 80 degrees. Its important characteristics are that it is remarkably steady in terms of flow properties and composition and that the ions, especially minor species, are favored in terms of heating and acceleration. We have proposed that the high speed wind, with its associated coronal holes, forms the basic mode of solar wind flow. In contrast, the low speed wind is inherently non-stationary, filamentary and not in equilibrium with conditions at the coronal base. It is presumably the result of continual reconfigurations of the force-free magnetic field in the low-latitude closed corona which allow trapped plasma to drain away along transiently open flux tubes. Observations of high speed solar wind close to its source are hampered by the essential heterogeneity of the corona, even at sunspot minimum. In particular it is difficult to determine more than limits to the density, temperature and wave amplitude near the coronal base as a result of contamination from fore- and back-ground plasma. We interpret the observations as indicating that the high speed solar wind originates in the chromospheric network, covering only about 1% of the surface of the sun, where the magnetic field is complex and not unipolar. As a result of small-scale reconnection events in this 'furnace', Alfven waves are generated with a flat spectrum covering the approximate range 10 kHz to 10 Hz. The plasma is likely to be produced as a result of downwards thermal conduction and possibly photoionization at the top of the low density chromospheric interface to the furnace, thus controlling the mass flux in the wind. The immediate source of free (magnetic) energy is in the form of granule-sized loops which are continually carried into the network from the sides. The resulting wave spectrum is such that energy can be efficiently transferred to the ions within a few solar radii of the base of the corona, favoring heavy species and creating stable, fast solar wind.

Axford, W. I.↗

NASA NTRS1982

Analysis of volatile metabolites in biological fluids as indicators of prodromal disease condition

The volatile profile cannot be defined as a single class of substances, rather it is a broad spectrum of materials of different polarities characterized by having a boiling-point in the low to medium range (up to approximately 300 C) and the fact that the compounds are suitable for gas chromatography without derivatization. The organic volatile profiles are very complex mixtures of metabolic byproducts, intermediates, and terminal products of enzymatic degradations composed mainly of alcohols, ketones, aldehydes, pyrazines, sulfides, isothiocyanates, pyrroles, and furans. The concentration of organic volatiles in biological fluids covers a wide range with many important components present at trace levels. The complexity of the organic volatile fraction requires the use of capillary columns for their separation.

Zlatkis, A.↗

NASA NTRS1981

Application of remote sensing to the photogeologic mapping of the region of the Itatiaia alkaline complex

Remote sensing methods applied to geologically complex areas, through interaction of ground truth and information obtained from multispectral LANDSAT images and radar mosaics were evaluated. The test area covers parts of Minos Gerais, Rio De Janeiro and Sao Paulo states and contains the alkaline complex of Itatiaia and surrounding Precambrian terrains. Geological and structural mapping was satisfactory; however, lithological varieties which form the massif's could not be identified. Photogeological lineaments were mapped, some of which represent the boundaries of stratigraphic units. Automatic processing was used to classify sedimentary areas, which includes the talus deposits of the alkaline massifs.

Dejesusparada, N.↗

NASA NTRS2014

A Framework for Land Cover Classification Using Discrete Return LiDAR Data: Adopting Pseudo-Waveform and Hierarchical Segmentation

Acquiring current, accurate land-use information is critical for monitoring and understanding the impact of anthropogenic activities on natural environments.Remote sensing technologies are of increasing importance because of their capability to acquire information for large areas in a timely manner, enabling decision makers to be more effective in complex environments. Although optical imagery has demonstrated to be successful for land cover classification, active sensors, such as light detection and ranging (LiDAR), have distinct capabilities that can be exploited to improve classification results. However, utilization of LiDAR data for land cover classification has not been fully exploited. Moreover, spatial-spectral classification has recently gained significant attention since classification accuracy can be improved by extracting additional information from the neighboring pixels. Although spatial information has been widely used for spectral data, less attention has been given to LiDARdata. In this work, a new framework for land cover classification using discrete return LiDAR data is proposed. Pseudo-waveforms are generated from the LiDAR data and processed by hierarchical segmentation. Spatial featuresare extracted in a region-based way using a new unsupervised strategy for multiple pruning of the segmentation hierarchy. The proposed framework is validated experimentally on a real dataset acquired in an urban area. Better classification results are exhibited by the proposed framework compared to the cases in which basic LiDAR products such as digital surface model and intensity image are used. Moreover, the proposed region-based feature extraction strategy results in improved classification accuracies in comparison with a more traditional window-based approach.

Light Detection & Ranging (LIDAR)↗

NASA NTRS1971

The radio astronomy explorer satellite, a low-frequency observatory.

The RAE-1 is the first spacecraft designed exclusively for radio astronomical studies. It is a small, but relatively complex, observatory including two 229-meter antennas, several radiometer systems covering a frequency range of 0.2 to 9.2 MHz, and a variety of supporting experiments such as antenna impedance probes and TV cameras to monitor antenna shape. Since its launch in July, 1968, RAE-1 has sent back some 10 billion data bits per year on measurements of long-wavelength radio phenomena in the magnetosphere, the solar corona, and the Galaxy. In this paper we describe the design, calibration, and performance of the RAE-1 experiments in detail.

Weber, R. R.↗

NASA NTRS1982

Evaluating near-surface soil moisture using Heat Capacity Mapping Mission data

Four dates of Heat Capacity Mapping Mission (HCMM) data were analyzed in order to evaluate HCMM thermal data use in estimating near-surface soil moisture in a complex agricultural landscape. Because of large spatial and temporal ground cover variations, HCMM radiometric temperatures alone did not correlate with soil water content. The radiometric temperatures consisted of radiance contributions from different canopies and their respective soil backgrounds. However, when surface soil temperatures were empirically estimated from HCMM temperatures and percent cover of each pixel, a highly significant correlation was obtained between the estimated soil temperatures and near-surface soil water content.

Heilman, J. L.↗

NASA NTRS1989

Current analytical gaps: Future needs for large space systems

Viewgraphs on current analytical gaps for future needs for large space systems are presented. Topics covered include: future spacecraft; common control objectives; accuracy requirements; increasing complexity; promising approaches; and analytical gaps.

Taylor, Larry↗

NASA NTRS2000

Verification and Validation Data for Computational Unsteady Aerodynamics

Computational Unsteady Aerodynamics computer codes are being increasingly used. In order to validate their results they must be tested against valid experimental data. The present report aims at collecting reliable experimental data on unsteady aerodynamics and presenting them in a form which permits use for verification of codes. For ease of handling, the data are also presented in machine readable form (CD-ROM). Data on increasingly complex generic forms were selected and the following categories are covered: flutter, buffet, stability and control, dynamic stall, cavity flows, store separation. Computational solutions are included in order to permit evaluation of codes and analysis of solutions which differ from experimental data.

Applied Vehicle Technology Panel (AVT)Task Group↗

NASA NTRS2021

DSN Radio Astronomy Spectrometer

The Deep Space Network (DSN) enables NASA to communicate with its deep space spacecraft. By virtue of its large antennas, the DSN can be used as a powerful instrument for radio astronomy. In particular, Deep Space Station (DSS) 43, the 70 m antenna at the Canberra Deep Space Communications Complex (CDSCC) has a K-band radio astronomy system covering a 10 GHz bandwidth at 17 to 27 GHz. This spectral range covers a number of atomic and molecular lines, produced in a rich variety of interstellar gas conditions. A new high-resolution spectrometer was deployed at CDSCC in November 2019 and connected to the K-band downconverter. The system has two different firmware modes: 1) Using a 65k-pt FFT to provide 32,768 spectral channels at ~30.5 kHz (0.45 km/s velocity resolution) and 2) Using a 16k-pt polyphase filterbank (PFB) to provide 8,192 spectral channels with ~122 kHz resolution (1.8 km/s velocity resolution). Previous work extensively described the spectrometer system. In this paper we present added functionality and updates to the commissioned spectrometer. The changes include developments in system timing, metadata, firmware and data products.

Bradford, Brian↗

NASA NTRS2024

Launch Complex 34 SWMU CC054 Hot Spot Area 6 Expansion - Phase Three Implementation Work Plan

This Hot Spot (HS) Area 6 Air Sparge Expansion – Phase Three Implementation Work Plan (IWP) was prepared by Tetra Tech, Inc., for the National Aeronautics and Space Administration (NASA) under the Indefinite Delivery Indefinite Quantity Contract 80KSC019D0011-80KSC019F0067, for the implementation of an Air Sparging (AS) Interim Measure (IM) at Launch Complex 34 (LC34), located at Cape Canaveral Space Force Station (CCSFS), Florida. LC34 has been designated as Solid Waste Management Unit (SWMU) CC054 under the Kennedy Space Center (KSC) Resource Conservation and Recovery Act (RCRA) operating permit. Expansion of the HS 6 IM will include installation of an additional 192 AS wells to depths of approximately 40 feet below land surface (bls) to remediate contaminated groundwater within two areas located west and northeast of the existing HS 6 AS treatment area. These areas were delineated via direct push technology investigations in September and October 2023. The expansion will target “hot spot” concentrations of cis-1,2-dichloroethene (cDCE) and vinyl chloride (VC), which are the contaminants of concern in these areas with concentrations greater than 10-times Florida Department of Environmental Protection Natural Attenuation Default Concentrations. The highest cDCE and VC concentrations detected in the proposed phase three expansion area were 58,000 micrograms per liter (μg/L) (32 to 36 feet bls) and 12,000 μg/L (23 to 27 feet bls), respectively. The objective for this expansion is to remediate contaminated groundwater within the treatment zone to support transition to long-term monitoring. This phase three expansion will add an additional 9.4 acres of treatment area to the HS 6 IM, which currently covers approximately 26.9 acres.

Launch Complex 34↗

NASA NTRS2014

Forward Bay Cover Separation Modeling and Testing for the Orion Multi-Purpose Crew Vehicle

Spacecraft multi‐body separation events during atmospheric descent require complex testing and analysis to validate the flight separation dynamics model and to verify no recontact. NASA Orion Multi‐Purpose Crew Vehicle (MPCV) teams examined key model parameters and risk areas to develop a robust but affordable test campaign in order to validate and verify the Forward Bay Cover (FBC) separation event for Exploration Flight Test‐1 (EFT‐1). The FBC jettison simulation model is highly complex, consisting of dozens of parameters varied simultaneously, with numerous multi‐parameter interactions (coupling and feedback) among the various model elements, and encompassing distinct near‐field, mid‐field, and far‐field regimes. The test campaign was composed of component‐level testing (for example gas‐piston thrusters and parachute mortars), ground FBC jettison tests, and FBC jettison air‐drop tests that were accomplished by a highly multi‐disciplinary team. Three ground jettison tests isolated the testing of mechanisms and structures to anchor the simulation models excluding aerodynamic effects. Subsequently, two air‐drop tests added aerodynamic and parachute parameters, and served as integrated system demonstrations, which had been preliminarily explored during the Orion Pad Abort‐1 (PA‐1) flight test in May 2010. Both ground and drop tests provided extensive data to validate analytical models and to verify the FBC jettison event for EFT‐1, but more testing is required to support human certification, for which NASA and Lockheed Martin are applying knowledge from Apollo and EFT‐1 testing and modeling to develop a robust but affordable human spacecraft capability.

Ali, Yasmin↗

NASA NTRS1973

Plan for the uniform mapping of earth resources and environmental complexes from Skylab imagery

The author has identified the following significant results. Below approximately 25% cover visual photointerpretation of vegetation analogs of Skylab 2 Sl9OA color infrared imagery is poor. Correct identifications of vegetation analogs in this category range from 28 to 57%. Good photointerpretation results (64 to 96%) were obtained on vegetation analogs with higher cover values. The four semidesert vegetation analogs (greasewood, saltbush, big sagebrush, and pinyon-juniper) are consistently distinguishable as a group. Photointerpretation accuracy equals 90.1%. When these same types are broken into two sub-groups (salt desert vegetation and shrub steppe/sparse pinyon-juniper vegetation) interpretation success drops to 76% and 85%, respectively. Band ratioing and transmittance differences between two forested analogs as imaged on Skylab 2 S19OA film shows significant differences. In the infrared wavelength both analogs have very similar transmittance characteristics while the visible wavelength shows separation between the two. Relative transmittance values for stands of ponderosa pine forestland and pinyon-juniper woodland are 719.3 + or - 65.9 and 223.6 + or - 48.1, respectively on negative transparencies. In image interpretation along the low-elevation fringe of forested regions these are the two forest analogs most frequently requiring separation.

Poulton, C. E.↗

NASA NTRS2015

Forward Bay Cover Separation Modeling and Testing for the Orion Multi-Purpose Crew Vehicle

Spacecraft multi-body separation events during atmospheric descent require complex testing and analysis to validate the flight separation dynamics models used to verify no re-contact. The NASA Orion Multi-Purpose Crew Vehicle (MPCV) architecture includes a highly-integrated Forward Bay Cover (FBC) jettison assembly design that combines parachutes and piston thrusters to separate the FBC from the Crew Module (CM) and avoid re-contact. A multi-disciplinary team across numerous organizations examined key model parameters and risk areas to develop a robust but affordable test campaign in order to validate and verify the FBC separation event for Exploration Flight Test-1 (EFT-1). The FBC jettison simulation model is highly complex, consisting of dozens of parameters varied simultaneously, with numerous multi-parameter interactions (coupling and feedback) among the various model elements, and encompassing distinct near-field, mid-field, and far-field regimes. The test campaign was composed of component-level testing (for example gas-piston thrusters and parachute mortars), ground FBC jettison tests, and FBC jettison air-drop tests that were accomplished by a highly multi-disciplinary team. Three ground jettison tests isolated the testing of mechanisms and structures to anchor the simulation models excluding aerodynamic effects. Subsequently, two air-drop tests added aerodynamic and parachute elements, and served as integrated system demonstrations, which had been preliminarily explored during the Orion Pad Abort-1 (PA-1) flight test in May 2010. Both ground and drop tests provided extensive data to validate analytical models and to verify the FBC jettison event for EFT-1. Additional testing will be required to support human certification of this separation event, for which NASA and Lockheed Martin are applying knowledge from Apollo and EFT-1 testing and modeling to develop a robust human-rated FBC separation event.

Ali, Yasmin↗

NASA NTRS1994

Recent Advances in Organic Cosmochemistry

The Astrochemistry Laboratory at NASA's Ames Research Center pursues a variety of activities, most of which center around the use of spectroscopy (ultraviolet to far-infrared) for the interpretation of astronomical and meteoritic data. One of our key activities is the study of the chemical and physical properties of cometary, interstellar, and planetary ice analogs and matrix-isolated molecules of astrophysical interest. As a result of these studies it is now known that a significant fraction of the carbon in the interstellar medium (ISM) is in reasonably complex forms, some of which are clearly of interest for exobiology. Examples of compounds known or suspected to be present in space include polycyclic aromatic hydrocarbons (PAHs), microdiamonds, an aliphatic-rich component found in the diffuse interstellar medium, and a variety of molecular species produced by the irradiation of mixed molecular ices in dense clouds. A number of the species produced by irradiation contain nitrogen and appear to offer an additional means of producing some of the amino acids found in meteorites. I will review these complex carbonaceous materials and discuss how they are connected with each other and the organic materials that ultimately ended up as part of our own Solar System. Specific points that will probably be covered include: (1) the composition of the ices in interstellar dense molecular clouds; (2) the more complex organic compounds produced when these ices are irradiated and/or warmed; (3) the detection of microdiamonds in space; (4) the discovery that aliphatic materials may constitute as much as 15% of all the carbon in the diffuse ISM, appears to be present everywhere in the galaxy, and yet seems to be present everywhere in the galaxy, and yet seems to be significantly concentrated towards the center of the galaxy.

Sandford, Scott A.↗

NASA NTRS1978

Analysis/design of strip reinforced random composites (strip hybrids)

Advanced analysis methods and composite mechanics were applied to a strip-reinforced random composite square panel with fixed ends to illustrate the use of these methods for the a priori assessment of the composite panel when subjected to complex loading conditions. The panel was assumed to be of E-glass random composite. The strips were assumed to be of three advanced unidirectional composites to cover a range of low, intermediate, and high modulus stiffness. The panels were assumed to be subjected to complex loadings to assess their adequacy as load-carrying members in auto body, aircraft engine nacelle and windmill blade applications. The results show that strip hybrid panels can be several times more structurally efficient than the random composite base materials. Some of the results are presented in graphical form and procedures are described for use of these graphs as guides for preliminary design of strip hybrids.

Chamis, C. C.↗