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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 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS2011

Alaska: Glaciers of Kenai Fjords National Park and Katmai and Lake Clark National Parks and Preserve

There are hundreds of glaciers in Kenai Fjords National Park (KEFJ) and Katmai National Park and Preserve (KATM) covering over 2276 sq km of park land (circa 2000). There are two primary glacierized areas in KEFJ -- the Harding Icefield and the Grewingk-Yalik Glacier Complex, and three primary glacierized areas in KATM - the Mt. Douglas area, the Kukak Volcano to Mt. Katmai area and the Mt. Martin area. Most glaciers in these parks terminate on land, though a few terminate in lakes. Only KEFJ has tidewater glaciers, which terminate in the ocean. Glacier mapping and analysis of the change in glacier extent has been accomplished on a decadal scale using satellite imagery, primarily Landsat data from the 1970s, 1980s, and from 2000. Landsat Multispectral Scanner (MSS), Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) imagery was used to map glacier extent on a park-wide basis. Classification of glacier ice using image processing software, along with extensive manual editing, was employed to create Geographic Information System (GIS) outlines of the glacier extent for each park. Many glaciers that originate in KEFJ but terminate outside the park boundaries were also mapped. Results of the analysis show that there has been a reduction in the amount of glacier ice cover in the two parks over the study period. Our measurements show a reduction of approximately 21 sq km, or -1.5% (from 1986 to 2000), and 76 sq km, or -7.7% (from 1986/87 to 2000), in KEFJ and KATM, respectively. This work represents the first comprehensive study of glaciers of KATM. Issues that complicate the mapping of glacier extent include: debris-cover (moraine and volcanic ash), shadows, clouds, fresh snow, lingering snow from the previous season, and differences in spatial resolution between the MSS and TM or ETM+ sensors. Similar glacier mapping efforts in western Canada estimate mapping errors of 3-4%. Measurements were also collected from a suite of glaciers in KEFJ and KATM detailing terminus positions and rates of recession using datasets including the 15-minute USGS quadrangle maps (1950/1951), Landsat imagery (1986/1987, 2000, 2006) and 2005 Ikonos imagery (KEFJ only).

Giffen, bruce A.↗
NASA NTRS2014

Alaska: Glaciers of Kenai Fjords National Park and Katmai National Park and Preserve

There are hundreds of glaciers in Kenai Fjords National Park (KEFJ) and Katmai National Park and Preserve (KATM) covering over 2,276 sq km of park land (ca. 2000). There are two primary glacierized areas in KEFJ (the Harding Icefield and the Grewingk-Yalik Glacier Complex) and three primary glacierized areas in KATM (the Mt. Douglas area, the Kukak Volcano to Mt. Katmai area, and the Mt. Martin area). Most glaciers in these parks terminate on land, though a few terminate in lakes. Only KEFJ has tidewater glaciers, which terminate in the ocean. Glacier mapping and analysis of the change in glacier extent has been accomplished on a decadal scale using satellite imagery, primarily Landsat data from the 1970s, 1980s, and from2000. Landsat Multispectral Scanner (MSS),Thematic Mapper (TM), and Enhanced Thematic Mapper Plus (ETM) imagery was used to map glacier extent on a park-wide basis. Classification of glacier ice using image-processing software, along with extensive manual editing, was employed to create Geographic Information System (GIS)outlines of the glacier extent for each park. Many glaciers that originate in KEFJ but terminate outside the park boundaries were also mapped. Results of the analysis show that there has been a reduction in the amount of glacier ice cover in the two parks over the study period. Our measurements show a reduction of approximately 21 sq km, or 1.5(from 1986 to 2000), and 76 sq km, or 7.7 (from19861987 to 2000), in KEFJ and KATM, respectively. This work represents the first comprehensive study of glaciers of KATM. Issues that complicate the mapping of glacier extent include debris cover(moraine and volcanic ash), shadows, clouds, fresh snow, lingering snow from the previous season, and differences in spatial resolution between the MSS,TM, or ETM sensors. Similar glacier mapping efforts in western Canada estimate mapping errors of 34. Measurements were also collected from a suite of glaciers in KEFJ and KATM detailing terminus positions and rates of recession using datasets including 15 min USGS quadrangle maps(19501951), Landsat imagery (19861987, 2000,2006), and 2005 IKONOS imagery (KEFJ only).

Kenai Fjords↗
NASA NTRS1971

Geophysical aspects of remote sensing

Results obtained through the NASA Earth Resources Aircraft Program at Mill Creek, Oklahoma, provide a case history example of the application of remote sensing to the identification of geologic rock units. Thermal infrared images are interpreted by means of a sequence of models of increasing complexity. The roles of various parameters are examined: rock properties (thermal inertia, albedo, emissivity), site location (latitude), season (sun's declination), atmospheric effects (cloud cover, transmission, air temperature), and topographic orientation (slope, azimuth). The results obtained at this site also illustrate the development of an important application of remote sensing in geologic identification. Relatively pure limestones and dolomites of the Mill Creek test area can be differentiated in nighttime infrared images, and facies changes between them can be detected along and across strike. The predominance on the earth's surface of sedimentary rocks, of which limestone and dolomite are major members, indicates the importance of this discrimination.

Watson, K.↗
NASA NTRS1973

Development of simulation computer complex specification

The Training Simulation Computer Complex Study was one of three studies contracted in support of preparations for procurement of a shuttle mission simulator for shuttle crew training. The subject study was concerned with definition of the software loads to be imposed on the computer complex to be associated with the shuttle mission simulator and the development of procurement specifications based on the resulting computer requirements. These procurement specifications cover the computer hardware and system software as well as the data conversion equipment required to interface the computer to the simulator hardware. The development of the necessary hardware and software specifications required the execution of a number of related tasks which included, (1) simulation software sizing, (2) computer requirements definition, (3) data conversion equipment requirements definition, (4) system software requirements definition, (5) a simulation management plan, (6) a background survey, and (7) preparation of the specifications.

Source record↗
NASA NTRS1977

Dynamic modeling of spacecraft in a collisionless plasma

A new computational model is described which can simulate the charging of complex geometrical objects in three dimensions. Two sample calculations are presented. In the first problem, the capacitance to infinity of a complex object similar to a satellite with solar array paddles is calculated. The second problem concerns the dynamical charging of a conducting cube partially covered with a thin dielectric film. In this calculation, the photoemission results in differential charging of the object.

Katz, I.↗
NASA NTRS1985

Nondestructive equipment study

Identification of existing nondestructive Evaluation (NDE) methods that could be used in a low Earth orbit environment; evaluation of each method with respect to the set of criteria called out in the statement of work; selection of the most promising NDE methods for further evaluation; use of selected NDE methods to test samples of pressure vessel materials in a vacuum; pressure testing of a complex monolythic pressure vessel with known flaws using acoustic emissions in a vacuum; and recommendations for further studies based on analysis and testing are covered.

Source record↗
NASA NTRS1991

A distributed fault-detection and diagnosis system using on-line parameter estimation

The development of a model-based fault-detection and diagnosis system (FDD) is reviewed. The system can be used as an integral part of an intelligent control system. It determines the faults of a system from comparison of the measurements of the system with a priori information represented by the model of the system. The method of modeling a complex system is described and a description of diagnosis models which include process faults is presented. There are three distinct classes of fault modes covered by the system performance model equation: actuator faults, sensor faults, and performance degradation. A system equation for a complete model that describes all three classes of faults is given. The strategy for detecting the fault and estimating the fault parameters using a distributed on-line parameter identification scheme is presented. A two-step approach is proposed. The first step is composed of a group of hypothesis testing modules, (HTM) in parallel processing to test each class of faults. The second step is the fault diagnosis module which checks all the information obtained from the HTM level, isolates the fault, and determines its magnitude. The proposed FDD system was demonstrated by applying it to detect actuator and sensor faults added to a simulation of the Space Shuttle Main Engine. The simulation results show that the proposed FDD system can adequately detect the faults and estimate their magnitudes.

Guo, T.-H.↗
NASA NTRS1991

Eigenvalue perturbation models for flexible structures

It is pointed out that real parametric modal frequency and damping variation for lightly damped systems does not resemble disks on the complex plane. Using complex uncertainty (and therefore disklike) models can introduce conservativeness in the design method. An alternative means of developing suitable complex uncertainty models is presented. It involves treating the uncertainty as perturbations to the system eigenvalues and using a particular linear fractional transformation to cover this uncertainty. This approach is applicable to modes within the bandwidth of control. It can be used in conjunction with the standard perturbation modeling approaches. A simple SISO (single-input single-output) example, motivated by a flexible truss experiment at the Jet Propulsion Laboratory, is discussed in order to illustrate the proposed approach.

Smith, Roy S.↗
NASA NTRS1993

Faulty behavior of asynchronous storage elements

It is often assumed that the faults in storage elements (SE's) can be modeled as output/input stuck-at-faults of the element. They are implicitly considered equivalent to the stuck-at faults in the combinational logic surrounding the SE cells. A more accurate higher level fault model for elementary SE's used in asynchronous circuits is presented. This model offers better representation of the physical failures. It is shown that the stuck-at model may be adequate if only modest fault coverage is desired. The enhanced model includes some common fault behaviors of SE's that are not covered by the stuck-at model. These include data-feed-through behaviors that cause the SE to be combinational. Fault models for complex SE cells can be obtained without a significant loss of information about the structure of the circuit.

Al-Assadi, Waleed K.↗
NASA NTRS2009

Jet Noise Modeling for Suppressed and Unsuppressed Aircraft in Simulated Flight

This document describes the development of further extensions and improvements to the jet noise model developed by Modern Technologies Corporation (MTC) for the National Aeronautics and Space Administration (NASA). The noise component extraction and correlation approach, first used successfully by MTC in developing a noise prediction model for two-dimensional mixer ejector (2DME) nozzles under the High Speed Research (HSR) Program, has been applied to dual-stream nozzles, then extended and improved in earlier tasks under this contract. Under Task 6, the coannular jet noise model was formulated and calibrated with limited scale model data, mainly at high bypass ratio, including a limited-range prediction of the effects of mixing-enhancement nozzle-exit chevrons on jet noise. Under Task 9 this model was extended to a wider range of conditions, particularly those appropriate for a Supersonic Business Jet, with an improvement in simulated flight effects modeling and generalization of the suppressor model. In the present task further comparisons are made over a still wider range of conditions from more test facilities. The model is also further generalized to cover single-stream nozzles of otherwise similar configuration. So the evolution of this prediction/analysis/correlation approach has been in a sense backward, from the complex to the simple; but from this approach a very robust capability is emerging. Also from these studies, some observations emerge relative to theoretical considerations. The purpose of this task is to develop an analytical, semi-empirical jet noise prediction method applicable to takeoff, sideline and approach noise of subsonic and supersonic cruise aircraft over a wide size range. The product of this task is an even more consistent and robust model for the Footprint/Radius (FOOTPR) code than even the Task 9 model. The model is validated for a wider range of cases and statistically quantified for the various reference facilities. The possible role of facility effects will thus be documented. Although the comparisons that can be accomplished within the limited resources of this task are not comprehensive, they provide a broad enough sampling to enable NASA to make an informed decision on how much further effort should be expended on such comparisons. The improved finalized model is incorporated into the FOOTPR code. MTC has also supported the adaptation of this code for incorporation in NASA s Aircraft Noise Prediction Program (ANOPP).

Stone, James R.↗
NASA NTRS2005

NASA Tech Briefs, April 2005

Gas-Tolerant Device Senses Electrical Conductivity of Liquid Nanoactuators Based on Electrostatic Forces on Dielectrics Replaceable Microfluidic Cartridges for a PCR Biosensor CdZnTe Image Detectors for Hard-X-Ray Telescopes High-Aperture-Efficiency Horn Antenna Full-Circle Resolver-to-Linear-Analog Converter Continuous, Full-Circle Arctangent Circuit Advanced Three-Dimensional Display System Automatic Focus Adjustment of a Microscope Topics covered include: FastScript3D - A Companion to Java 3D; Generating Mosaics of Astronomical Images; Simulating Descent and Landing of a Spacecraft; Simulating Vibrations in a Complex Loaded Structure; Rover Sequencing and Visualization Program; Software Template for Instruction in Mathematics; Support for User Interfaces for Distributed Systems; Nanostructured MnO2-Based Cathodes for Li-Ion/Polymer Cells; Multi-Layer Laminated Thin Films for Inflatable Structures; Two-Step Laser Ranging for Precise Tracking of a Spacecraft; Growing Aligned Carbon Nanotubes for Interconnections in ICs; Multilayer Composite Pressure Vessels; Texturing Blood-Glucose-Monitoring Optics Using Oxygen Beams; Fault-Tolerant Heat Exchanger; Atomic Clock Based on Opto-Electronic Oscillator; Microfocus/Polycapillary-Optic Crystallographic X-Ray Sys; Depth-Penetrating Luminescence Thermography of Thermal- Barrier Coatings; One-Dimensional Photonic Crystal Superprisms; Measuring Low-Order Aberrations in a Segmented Telescope; Mapping From an Instrumented Glove to a Robot Hand; Application of the Hilbert-Huang Transform to Financial Data; Optimizing Parameters for Deep-Space Optical Communication; and Low-Shear Microencapsulation and Electrostatic Coating.

Source record↗
NASA NTRS1999

The Cognitive Consequences of Patterns of Information Flow

The flight deck of a modern commercial airliner is a complex system consisting of two or more crew and a suite of technological devices. The flight deck of the state-of-the-art Boeing 747-400 is shown. When everything goes right, all modern flight decks are easy to use. When things go sour, however, automated flight decks provide opportunities for new kinds of problems. A recent article in Aviation Week cited industry concern over the problem of verifying the safety of complex systems on automated, digital aircraft, stating that the industry must "guard against the kind of incident in which people and the automation seem to mismanage a minor occurrence or non-routine situation into larger trouble." The design of automated flight deck systems that flight crews find easy to use safely is a challenge in part because this design activity requires a theoretical perspective which can simultaneously cover the interactions of people with each other and with technology. In this paper, some concepts that can be used to understand the flight deck as a system that is composed of two or more pilots and a complex suite of automated devices is introduced.

Hutchins, Edwin↗
NASA NTRS1973

Principal sources and dispersal patterns of suspended particulate matter in nearshore surface waters of the northeast Pacific Ocean and seasonal variation in snow cover in the Sierra Nevada

The author has identified the following significant results. ERTS-1 imagery used in conjunction with the surface-drift cards indicated a southerly flow direction of the central California near surface coastal currents during mid-June 1973. The near-surface currents off northern California and southern Oregon were more complex. Some drift cards were recovered north and some south of their release points; however, the prevalent direction of flow was northerly. General agreement in flow direction of coastal currents obtained from ERTS-1 imagery and drift card data reinforces the image interpretation. Complete seasonal coverage of nearshore circulation interpreted from ERTS-1 imagery will provide information necessary for proper coastal zone management. Extent of snow cover can be readily delimited on ERTS-1 band 5. In the central Sierra Nevada Mountains this past winter season, the snow line, as recorded by ERTS-1, reached an elevation of less than 1500 meters in January but had melted back to between 2500 and 3000 meters by the end of May. ERTS-1 imagery seems to provide sufficient resolution to make it a useful tool for monitoring changes in snow cover in the Sierra Nevada Mountains.

Carlson, P. R.↗
NASA NTRS2023

The 17 April 2021 Widespread Solar Energetic Particle Event

A complex and long-lasting solar eruption on 17 April 2021 produced a widespread solar energetic particle (SEP) event that was observed by five longitudinally well-separated observers in the inner heliosphere that covered distances to the Sun from 0.42 to 1 au: BepiColombo, Parker Solar Probe, Solar Orbiter, STEREO A, and near-Earth spacecraft. The event was the second widespread SEP event detected in solar cycle 25, and it produced relativistic electrons and protons. It was associated with a long-lasting solar hard X-ray flare that showed multiple hard X-ray peaks over a duration of one hour. The event was further accompanied by a medium-fast coronal mass ejection (CME) with a speed of 880 km s -1 that drove a shock, an extreme ultraviolet wave, and long-lasting and complex radio burst activity that showed four distinct type III burst groups over a period of 40 min. We aim to understand the reason for the wide spread of elevated SEP intensities in the inner heliosphere as well as identify the underlying source regions of the observed energetic electrons and protons. We applied a comprehensive multi-spacecraft analysis of remote-sensing observations and in situ measurements of the energetic particles and interplanetary context to attribute the SEP observations at the different locations to the various potential source regions at the Sun. We used an ENLIL simulation to characterize the complex interplanetary state and its role in the energetic particle transport. The magnetic connection between each spacecraft and the Sun was determined using ballistic backmapping in combination with potential field source surface extrapolations in the lower corona. Using also a reconstruction of the coronal shock front, we then determined the times when the shock establishes magnetic connections with the different observers. Radio observations were used to characterize the directivity of the four main injection episodes, which were then employed in a 2D SEP transport simulation to test the importance of these different injection episodes. A comprehensive timing analysis of the inferred solar injection times of the SEPs observed at each spacecraft suggests different source processes being important for the electron and proton events. Comparison among the characteristics and timing of the potential particle sources, such as the CME-driven shock or the flare, suggests a stronger shock contribution for the proton event and a more likely flare-related source for the electron event. In contrast to earlier studies on widespread SEP events, we find that in this event an important ingredient for the wide SEP spread was the wide longitudinal range of about 110 o covered by distinct SEP injections, which is also supported by our SEP transport modeling.

sun↗
NASA NTRS1992

Hypersonic flows as related to the national aerospace plane

The study in the last 6 months has observed a clear evidence that the current two-equation models tend to under-predict flow separation and over-predict heat transfer rate near flow re-attachment regions. In hypersonic flow calculations, these model deficiencies appear to be even more pronounced. This is particularly true in the incapability of the model to predict the extent of the flow separation. Two major deficiencies of the current two-equation models in predicting complex hypersonic flows have been reported, i.e., under-prediction of flow separation and over-prediction of peak heat transfer rate. Two modifications to the k - epsilon model were reported and tested over a range of flows. Based on our limited study, the modified models have been found to give better agreements in both surface pressure and heat transfer predictions for several complex shock-wave boundary-layer interaction flows. However, in order to confirm our observation, more calculations will be performed in the future study covering a wider range of flows and conditions than reported here.

Kussoy, Marvin↗
NASA NTRS1993

The ROSAT spectrum of 3C 351 - A warm absorber in an X-ray-'quiet' quasar?

3C 351 is one of the most X-ray-quiet radio quasars (alpha(ox) about 1.6). We have observed 3C 351 with the ROSAT position sensitive proportional counter (PSPC) and find a complex X-ray spectrum which is not well reproduced by a power law plus low-energy cut-off model. Soft excess, partial covering, and 'warm absorber' models can all produce acceptable fits, although only the warm absorber model gives typical values for the high-energy continuum slope. The alpha(ox) measured by using quasi-simultaneous ROSAT, MMT, and HST observations is in the range 1.5-1.6, significantly above the average of 1.37 for a complete sample of 33 3CR quasars. If the soft excess or partial covering models are correct, 3C 351 appears X-ray-quiet in the PSPC band because it has an extremely steep or flat intrinsic high-energy spectral slope. However, if the warm absorber model is correct, the quasar is intrinsically X-ray-quiet; the normalization of the intrinsic (unabsorbed) X-ray emission is unusually low relative to the optical luminosity. We investigate the properties of our warm absorber model in some detail. The apparently complicated behavior of the fit parameters may be understood by considering the effects of changing absorbing column and ionization parameter on intrinsic power-law-spectra of different slopes.

Fiore, Fabrizio↗
NASA NTRS1995

Turbulence program for propulsion systems

Program goals at the Center for Modeling of Turbulence and Transition (CMOTT), NASA Lewis Research Center, are (1) to develop reliable turbulence (including bypass transition) and combustion models for complex flows in propulsion systems and (2) to integrate developed models into deliverable CFD tools for propulsion systems in collaboration with industry. This viewgraph presentation covers the following topics: development of turbulence and combustion models; collaboration with industry and technology transfer; isotropic eddy viscosity models; algebraic Reynolds stress models; scalar turbulence models; second order closure models; multiple scale k-epsilon models; and PDF modeling of turbulent reacting flows.

Shih, Tsan-Hsing↗
NASA NTRS1998

Thermomechanical Postbuckling of Shells

A number of issues involving the postbuckling of doubly-curved panels exposed to a non-uniform temperature field and subjected to a system of mechanical loads are considered in this paper. Effects played by transverse shear, initial geometric imperfections, membrane and thickness-wise temperature gradient, tangential edge constraints, linear/non-linear elastic foundation are incorporated and their implications on the non-linear response behavior of shells are discussed. Issues related with the delay of the occurrence of the snap-through buckling, alleviation of its intensity and even with its removal are addressed and remarks on conditions rendering a curved panel insensitive to initial geometric imperfections are included. Results on small vibration of shells about sub- and post-critical ranges are provided and structural modeling issues playing a non-negligible role towards a reliable prediction of the postbuckling behavior of shells under complex loading conditions are discussed. Results on non-linear response of flat reinforced panels subjected to thermomechanical loads are also presented. Finally, problems not covered by this article are briefly indicated.

Librescu, Liviu↗