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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 NTRSDate not supplied

Two-Phase Flow in Filters and Orifices: ISS Packed Bed Reactor Experiment Water Recovery Series (PBRE-WRS)

Understanding the hydrodynamics of adiabatic two-phase flows in packed bed reactors offers numerous benefits. It enables the optimization of chemical reactions rates and products which results in more efficient and compact reactors, thus reducing space and resource requirements, crucial for long duration space missions. The Packed Bed Reactor Experiment-Water Recovery Series (PBRE-WRS) is a flight experiment planned for operation on the Microgravity Science Glove box (MSG) facility of the International Space Station (ISS). The objective of the experiment is to validate hydrodynamic models at a range of gas and liquid flow rates, where these models are used in the design of processes for life support systems in microgravity. The microgravity environment allows for measurement and observation of aspects of fluid dynamics that are unique when compared to observations made in full or partial gravity environments. The experiment consists of testing two-phase flow hydrodynamics in three different filters, four (4) orifices and one check valve test articles. The experiment utilizes the hardware of the previously flown PBRE and PBRE-2 with packed beds of different packings materials and sizes. The fluid system of the PBRE-WRS consists of a nitrogen gas delivery and water delivery subsystems. The gas delivery subsystem can accommodate two ranges of gas flow rates, just as for the water delivery system. The nitrogen gas loop is open whereas the water loop is closed. Gas is separated from the water using a gas-liquid phase separator which is located in the water delivery module. Preliminary results from ground testing show the pressure drop across the filters increasing at different rates with the liquid and gas flow rates. In this work, a detailed system description is presented along with a summary of results from ground performance testing of different test sections in an end-to-end preflight testing campaign.

ISS↗
DOE OSTI2024

LYNM-PE1 Seismic Parameters from Borehole Log, Laboratory, and Tabletop Measurements

The goal of this work is to provide a database of quality-checked seismic parameters that can be integrated with the Geologic Framework Model (GFM) for the LYNM-PE1 (Low Yield Nuclear Monitoring – Physical Experiment 1) testbed. We integrated data from geophysical borehole logs, tabletop measurements on collected core, and laboratory measurements. We reviewed for internal consistency among each measurement type, documented the caveats of measurement conditions, and integrated lithologic logs to check the validity of outlier values. The resulting consolidated parameter tables can be used as inputs for modeling and analysis codes and are designed to interface with the GFM, which is being actively developed.

58 GEOSCIENCES↗
DOE OSTI2021

Speculative instruction wakeup to tolerate draining delay of memory ordering violation check buffers

A technique for speculatively executing load-dependent instructions includes detecting that a memory ordering consistency queue is full for a completed load instruction. The technique also includes storing data loaded by the completed load instruction into a storage location for storing data when the memory ordering consistency queue is full. The technique further includes speculatively executing instructions that are dependent on the completed load instruction. The technique also includes in response to a slot becoming available in the memory ordering consistency queue, replaying the load instruction. The technique further includes in response to receiving loaded data for the replayed load instruction, testing for a data mis-speculation by comparing the loaded data for the replayed load instruction with the data loaded by the completed load instruction that is stored in the storage location.

Kalamatianos, John↗
DOE OSTI2020

Heterotic instantons for monad and extension bundles

We consider non-perturbative superpotentials from world-sheet instantons wrapped on holomorphic genus zero curves in heterotic string theory. These superpotential contributions feature prominently in moduli stabilization and large field axion inflation, which makes their presence or absence, as well as their functional dependence on moduli, an important issue. We develop geometric methods to compute the instanton superpotentials for heterotic string theory with monad and extension bundles. Using our methods, we find a variety of examples with a non-vanishing superpotential. In view of standard vanishing theorems, we speculate that these results are likely to be attributed to the non-compactness of the instanton moduli space. We test this proposal, for the case of monad bundles, by considering gauged linear sigma models where compactness of the instanton moduli space can be explicitly checked. In all such cases, we find that the geometric results are consistent with the vanishing theorems. Surprisingly, linearly dependent Pfaffians even arise for cases with a non-compact instanton moduli space. This suggests some gauged linear sigma models with a non-compact instanton moduli space may still have a vanishing instanton superpotential.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2024

Dark sink enhances the direct detection of freeze-in dark matter

We describe a simple dark sector structure which, if present, has implications for the direct detection of dark matter (DM); the dark sink. A dark sink transports energy density from the DM into light dark-sector states that do not appreciably contribute to the DM density. As an example, we consider a light, neutral fermion ψ which interacts solely with DM Χ via the exchange of a heavy scalar Φ. We illustrate the impact of a dark sink by adding one to a DM freeze-in model in which Χ couples to a light dark photon γ' which kinetically mixes with the Standard Model (SM) photon. This freeze-in model (absent the sink) is itself a benchmark for ongoing experiments. In some cases, the literature for this benchmark has contained errors; we correct the predictions and provide them as a public code. We then analyze how the dark sink modifies this benchmark, solving coupled Boltzmann equations for the dark-sector energy density and DM yield. We check the contribution of the dark sink ψ’s to dark radiation; consistency with existing data limits the maximum attainable cross section. For DM with a mass between MeV –Ο⁡(10 GeV), adding the dark sink can increase predictions for the direct detection cross section all the way up to the current limits.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS1987

Independent Orbiter Assessment (IOA): Analysis of the orbiter main propulsion system

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items (PCIs). To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results for the Orbiter Main Propulsion System (MPS) hardware are documented. The Orbiter MPS consists of two subsystems: the Propellant Management Subsystem (PMS) and the Helium Subsystem. The PMS is a system of manifolds, distribution lines and valves by which the liquid propellants pass from the External Tank (ET) to the Space Shuttle Main Engines (SSMEs) and gaseous propellants pass from the SSMEs to the ET. The Helium Subsystem consists of a series of helium supply tanks and their associated regulators, check valves, distribution lines, and control valves. The Helium Subsystem supplies helium that is used within the SSMEs for inflight purges and provides pressure for actuation of SSME valves during emergency pneumatic shutdowns. The balance of the helium is used to provide pressure to operate the pneumatically actuated valves within the PMS. Each component was evaluated and analyzed for possible failure modes and effects. Criticalities were assigned based on the worst possible effect of each failure mode. Of the 690 failure modes analyzed, 349 were determined to be PCIs.

Mcnicoll, W. J.↗
NASA NTRS1989

A cache-aided multiprocessor rollback recovery scheme

This paper demonstrates how previous uniprocessor cache-aided recovery schemes can be applied to multiprocessor architectures, for recovering from transient processor failures, utilizing private caches and a global shared memory. As with cache-aided uniprocessor recovery, the multiprocessor cache-aided recovery scheme of this paper can be easily integrated into standard bus-based snoopy cache coherence protocols. A consistent shared memory state is maintained without the necessity of global check-pointing.

Wu, Kun-Lung↗
NASA NTRS1989

A polynomial time algorithm for checking the robust stability of a polytope of polynomials

An efficient algorithm to check the robust stability of a polytope of polynomials is proposed. This problem is equivalent to a zero-exclusion condition at each frequency. It is shown that such a condition has to be checked at only a finite number of frequencies. This problem is formulated as a parametric linear program, which can be solved by the simplex procedure with additional computations between steps, consisting of polynomial evaluations and calculation of positive polynomial roots. The algorithm requires a finite number of steps (corresponding to frequency checks), and, in the important case of the polytope of parameters being a hypercube, this number is at most O(m3n), where n is the degree of the polynomials in the family and m is the number of parameters.

Sideris, Athanasios↗
NASA NTRS2013

Support Routines for In Situ Image Processing

This software consists of a set of application programs that support ground-based image processing for in situ missions. These programs represent a collection of utility routines that perform miscellaneous functions in the context of the ground data system. Each one fulfills some specific need as determined via operational experience. The most unique aspect to these programs is that they are integrated into the large, in situ image processing system via the PIG (Planetary Image Geometry) library. They work directly with space in situ data, understanding the appropriate image meta-data fields and updating them properly. The programs themselves are completely multimission; all mission dependencies are handled by PIG. This suite of programs consists of: (1)marscahv: Generates a linearized, epi-polar aligned image given a stereo pair of images. These images are optimized for 1-D stereo correlations, (2) marscheckcm: Compares the camera model in an image label with one derived via kinematics modeling on the ground, (3) marschkovl: Checks the overlaps between a list of images in order to determine which might be stereo pairs. This is useful for non-traditional stereo images like long-baseline or those from an articulating arm camera, (4) marscoordtrans: Translates mosaic coordinates from one form into another, (5) marsdispcompare: Checks a Left Right stereo disparity image against a Right Left disparity image to ensure they are consistent with each other, (6) marsdispwarp: Takes one image of a stereo pair and warps it through a disparity map to create a synthetic opposite- eye image. For example, a right eye image could be transformed to look like it was taken from the left eye via this program, (7) marsfidfinder: Finds fiducial markers in an image by projecting their approximate location and then using correlation to locate the markers to subpixel accuracy. These fiducial markets are small targets attached to the spacecraft surface. This helps verify, or improve, the pointing of in situ cameras, (8) marsinvrange: Inverse of marsrange . given a range file, re-computes an XYZ file that closely matches the original. . marsproj: Projects an XYZ coordinate through the camera model, and reports the line/sample coordinates of the point in the image, (9) marsprojfid: Given the output of marsfidfinder, projects the XYZ locations and compares them to the found locations, creating a report showing the fiducial errors in each image. marsrad: Radiometrically corrects an image, (10) marsrelabel: Updates coordinate system or camera model labels in an image, (11) marstiexyz: Given a stereo pair, allows the user to interactively pick a point in each image and reports the XYZ value corresponding to that pair of locations. marsunmosaic: Extracts a single frame from a mosaic, which will be created such that it could have been an input to the original mosaic. Useful for creating simulated input frames using different camera models than the original mosaic used, and (12) merinverter: Uses an inverse lookup table to convert 8-bit telemetered data to its 12-bit original form. Can be used in other missions despite the name.

Deen, Robert G.↗
NASA NTRS1999

Skin Friction Drag Predictions: Summary of CFD Cross Checks, Wing/Body

The objective of the present study was to address the questions of: 1) how reliably or consistently the Navier-Stokes methods and processes used by the various organizations can predict integrated skin friction drag, and 2) how well the methods can predict trends within a family of optimized configurations. As a first step, all available skin friction drag predictions were accumulated to obtain a mean and standard deviation for the TCA (Technology Concept Airplane) baseline and each of the optimized configurations. It is observed that the optimization process has had little effect on the predicted skin friction drags. The variation in the mean that is observed is dwarfed by the standard deviations. In order to understand the reasons for the relatively large spreads in the computed results, a number of auxiliary computations have been performed using the UPS and OVERFLOW codes in an effort to identify and quantity potential sources of the variations.

Lawrence, Scott↗
NASA NTRS1973

Investigation of the detection and monitoring of forest insect infestations in the Sierra Nevada Mountains of California

The author has identified the following significant results. In earlier reports it has been indicated that it is possible to delineate areas of lodgepole pine timber mortality into three degrees of damage from enlarged ERTS-1 color composites; light, medium, and heavy. It can also be confidently reported that it is now possible to detect all major areas of lodgepole pine defoliated by the needle miner. It has also been confirmed, through ground checking and helicopter observation that previous designation of the following features have been consistently accurate: timbered vs non-timbered areas; timber types; damaged vs undamaged areas; lakes, dome shadows which resemble lakes, mountain meadows, pasture and agricultural land, desert; riparian vegetation; and glaciers.

Hall, R. C.↗
NASA NTRS1980

The Remote Computer Control (RCC) system

A system to remotely control job flow on a host computer from any touchtone telephone is briefly described. Using this system a computer programmer can submit jobs to a host computer from any touchtone telephone. In addition the system can be instructed by the user to call back when a job is finished. Because of this system every touchtone telephone becomes a conversant computer peripheral. This system known as the Remote Computer Control (RCC) system utilizes touchtone input, touchtone output, voice input, and voice output. The RCC system is microprocessor based and is currently using the INTEL 80/30microcomputer. Using the RCC system a user can submit, cancel, and check the status of jobs on a host computer. The RCC system peripherals consist of a CRT for operator control, a printer for logging all activity, mass storage for the storage of user parameters, and a PROM card for program storage.

Holmes, W.↗
NASA NTRS1982

Measurement of the line-of-sight velocity of high-altitude barium clouds A technique

It is demonstrated that for maximizing the scientific output of future ionospheric and magnetospheric ion cloud release experiments a new type of instrument is required which will measure the line-of-sight velocity of the ion cloud by the Doppler technique. A simple instrument was constructed using a 5-cm diam solid Fabry-Perot etalon coupled to a low-light-level integrating TV camera. It was demonstrated that the system has both the sensitivity and spectral resolution for detection of ion clouds and measurement of their line-of-sight Doppler velocity. The tests consisted of (1) a field experiment using a rocket barium cloud release to check sensitivity, and (2) laboratory experiments to show the spectral resolving capabilities of the system. The instrument was found to be operational if the source was brighter than approximately 1 kR, and it had a wavelength resolution much better than 0.2 A, which corresponds to approximately 12 km/sec or in the case of barium ion an acceleration potential of 100 V. The instrument is rugged and, therefore, simple to use in field experiments or on flight instruments. The sensitivity limit of the instrument can be increased by increasing the size of the etalon.

Mende, S. B.↗
NASA NTRS1981

Techniques for the measurements of the line of sight velocity of high altitude Barium clouds

It is demonstrated that for maximizing the scientific output of future ion cloud release experiments a new type of instrument is required which will measure the line of sight velocity of the ion cloud by the Doppler Technique. A simple instrument was constructed using a 5 cm diameter solid Fabry-Perot etalon coupled to a low light level integrating television camera. It was demonstrated that the system has both the sensitivity and spectral resolution for the detection of ion clouds and the measurement of their line of sight Doppler velocity. The tests consisted of (1) a field experiment using a rocket barium cloud release to check the sensitivity, (2) laboratory experiments to show the spectral resolving capabilities of the system. The instrument was found to be operational if the source was brighter than about 1 kilorayleigh and it had a wavelength resolution much better than .2A which corresponds to about 12 km/sec or an acceleration potential of 100 volts.

Mende, S. B.↗
NASA NTRS1989

Superaromatics: The key to a unified cosmic dust theory

The theory of Superaromatics, the key to a unified cosmic dust theory, was constructed by analyzing several thousand astronomical features covering every major aspect of astrophysics and astrochemistry relating to dust. To insure consistency between disciplines, the logical structure of the conclusions in each field was checked rather than accepting the current consensus. No substantial contradictory features are known to the author. The analysis falls into seven major parts: (1) kinetics of grain formation and destruction; (2) optical spectra of the interstellar medium (ISM); (3) meteorite interplanetary dust particle (IPD) chemistry; (4) structure and chemistry of the interstellar medium arising from surface catalysis; (6) dynamics of circumstellar and interstellar dust clouds, including galactic morphology; and (7) the chemistry and physics of previously unidentified compounds. Only tentative conclusions are presented here. The principle conclusion is that quantum mechanics as it is normally formulated is incomplete. The probable cause is that it is formulated with complex numbers rather than the more fundamental quaternion system. The manifestation in astrochemistry is that the most stable compounds are superaromatic and exotic enough to confound most classical analysis.

Manuel, Lawrence R.↗
NASA NTRS1994

Theoretical studies of a molecular beam generator

We consider the problem of modeling a high temperature diatomic gas N2 flowing through a converging-diverging high expansion nozzle. The problem is modeled in two ways. The first model uses a single temperature with variable specific heats as functions of this temperature. For the second model we assume that the various degrees of freedom all have a Boltzmann population distribution which means that each degree of freedom has its own temperature and consequently each system state can be characterized by these temperatures. This suggests the formulation of a second model with a vibrational degree of freedom as having its own temperature along with a rotational-translational degree of freedom with its own temperature. Initially the vibrational degree of freedom is excited by heating the gas to a high temperature. As the high temperature gas expands through the nozzle throat there is a sudden drop in the rotational-translational temperature along with a finite relaxation time for the vibrational degree of freedom to achieve equilibrium with the rotational-translational degree of freedom. That is, the temperature change that occurs when the N2 gas passes through the nozzle throat is so great that the changes in the vibrational degree of freedom lags behind the rotational-translational energy changes. The resulting relaxation time is finite. It is in this context that the term nonequilibrium is used. That is, the term nonequilibrium denotes the fact that the energy content of the various degrees of freedom are characterized by two temperatures. We neglect any chemical reactions resulting from the high temperatures which could also add nonequilibrium effects. We develop the basic equations for the two models in various forms in order to check the derivations with other sources. The final form which is solved numerically consists of the scaled equations in a conservative dimensionless form.

Heinbockel, John H.↗
NASA NTRS1994

Evaluation of SSME test data reduction methods

Accurate prediction of hardware and flow characteristics within the Space Shuttle Main Engine (SSME) during transient and main-stage operation requires a significant integration of ground test data, flight experience, and computational models. The process of integrating SSME test measurements with physical model predictions is commonly referred to as data reduction. Uncertainties within both test measurements and simplified models of the SSME flow environment compound the data integration problem. The first objective of this effort was to establish an acceptability criterion for data reduction solutions. The second objective of this effort was to investigate the data reduction potential of the ROCETS (Rocket Engine Transient Simulation) simulation platform. A simplified ROCETS model of the SSME was obtained from the MSFC Performance Analysis Branch . This model was examined and tested for physical consistency. Two modules were constructed and added to the ROCETS library to independently check the mass and energy balances of selected engine subsystems including the low pressure fuel turbopump, the high pressure fuel turbopump, the low pressure oxidizer turbopump, the high pressure oxidizer turbopump, the fuel preburner, the oxidizer preburner, the main combustion chamber coolant circuit, and the nozzle coolant circuit. A sensitivity study was then conducted to determine the individual influences of forty-two hardware characteristics on fourteen high pressure region prediction variables as returned by the SSME ROCETS model.

Santi, L. Michael↗
NASA NTRS1995

Determination of hydrocarbon abundances and the strength of eddy mixing in the stratosphere of Neptune: Analysis of UVS solar occultation lightcurves

Work on completing our analysis of the Voyager UVS solar occultation data acquired during Neptune encounter is essentially complete, as testified by the attached poster materials. The photochemical modeling addresses the recent revision in branching ratios for radical production in the photolysis of methane at H Lyman alpha implied by the lab measurements of Mordaunt et al. (1993). The software generated in this effort has been useful for checking the degree to which photochemical models addressing other datasets (mainly infrared) are consistent with the UVS data. This work complements the UVS modeling results in that the IR data refer to deeper pressure levels; as regards the modeling of UVS data, the most significant result is the convincing support for the presence of a stagnant lower stratosphere. Evidence for strong dynamical (mixing) transport of minor constituents at shallower pressures is provided by the UVS data analysis.

Bishop, James↗