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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS1998

Reusable Rocket Engine Operability Modeling and Analysis

This paper describes the methodology, model, input data, and analysis results of a reusable launch vehicle engine operability study conducted with the goal of supporting design from an operations perspective. Paralleling performance analyses in schedule and method, this requires the use of metrics in a validated operations model useful for design, sensitivity, and trade studies. Operations analysis in this view is one of several design functions. An operations concept was developed given an engine concept and the predicted operations and maintenance processes incorporated into simulation models. Historical operations data at a level of detail suitable to model objectives were collected, analyzed, and formatted for use with the models, the simulations were run, and results collected and presented. The input data used included scheduled and unscheduled timeline and resource information collected into a Space Transportation System (STS) Space Shuttle Main Engine (SSME) historical launch operations database. Results reflect upon the importance not only of reliable hardware but upon operations and corrective maintenance process improvements.

Christenson, R. L.↗
DOE OSTI2016

Sensitivity analysis of simulated SOA loadings using a variance-based statistical approach: SENSITIVITY ANALYSIS OF SOA

We investigate the sensitivity of secondary organic aerosol (SOA) loadings simulated by a regional chemical transport model to 7 selected tunable model parameters: 4 involving emissions of anthropogenic and biogenic volatile organic compounds, anthropogenic semi-volatile and intermediate volatility organics (SIVOCs), and NOx, 2 involving dry deposition of SOA precursor gases, and one involving particle-phase transformation of SOA to low volatility. We adopt a quasi-Monte Carlo sampling approach to effectively sample the high-dimensional parameter space, and perform a 250 member ensemble of simulations using a regional model, accounting for some of the latest advances in SOA treatments based on our recent work. We then conduct a variance-based sensitivity analysis using the generalized linear model method to study the responses of simulated SOA loadings to the tunable parameters. Analysis of SOA variance from all 250 simulations shows that the volatility transformation parameter, which controls whether particle-phase transformation of SOA from semi-volatile SOA to non-volatile is on or off, is the dominant contributor to variance of simulated surface-level daytime SOA (65% domain average contribution). We also split the simulations into 2 subsets of 125 each, depending on whether the volatility transformation is turned on/off. For each subset, the SOA variances are dominated by the parameters involving biogenic VOC and anthropogenic SIVOC emissions. Furthermore, biogenic VOC emissions have a larger contribution to SOA variance when the SOA transformation to non-volatile is on, while anthropogenic SIVOC emissions have a larger contribution when the transformation is off. NOx contributes less than 4.3% to SOA variance, and this low contribution is mainly attributed to dominance of intermediate to high NOx conditions throughout the simulated domain. The two parameters related to dry deposition of SOA precursor gases also have very low contributions to SOA variance. This study highlights the large sensitivity of SOA loadings to the particle-phase transformation of SOA volatility, which is neglected in most previous models.

Shrivastava, Manish↗
NASA NTRS1988

An approach to simultaneous system design. II - Nonswitching gain and dynamic feedback compensation by algebraic geometric methods

This paper studies structured uncertainty problems in feedback system design, considers a compact parameterization of the space of linear dynamical systems and introduces 'base points' and 'critical points' as two algebraic-geometric objects that have significance in sensitivity and robustness studies, respectively. Using the Nevanlinna-Pick interpolation theory, the author obtains a necessary and sufficient condition for simultaneous stabilization of a structured one-parameter family of plants. A recent result due to Kharitonov, on the simultaneous stability of a parameterized family of polynomials, leads to a sufficiency condition for simultaneous stabilization of a structured multiparameter family of plants. Furthermore, the author considers 'simultaneous pole placement' of an r-tuple of plants as a means to arbitrarily tune the natural frequencies of a multimode linear dynamical system. The concept of 'nondegenerate' and 'twisted' r-tuples of plants is introduced as the pole placement problem is studied via Schubert enumerative geometry as an intersection problem on the associated Grassmannian. Various other design problems, viz., the strong stabilization problem and the dead beat control problem, are also considered.

Ghosh, Bijoy K.↗
NASA NTRS1994

Conceptual radiometer design studies for Earth observations from low Earth orbit

A conceptual radiometer design study was performed to determine the optimum design approach for spaceborne radiometers in low Earth orbit. Radiometric system configurations which included total power radiometers, unbalanced Dicke radiometers, and balanced Dicke, or as known as noise injection, radiometers were studied. Radiometer receiver configurations which were analyzed included the direct detection radiometer receiver, the double sideband homodyne radiometer receiver, and the single sideband heterodyne radiometer receiver. Radiometer system performance was also studied. This included radiometric sensitivity analysis of the three different radiometer system configurations studied. Both external and internal calibration techniques were analyzed. An accuracy analysis with and without mismatch losses was performed. It was determined that the balanced Dicke radiometer system configuration with direct detection receivers and external calibrations was optimum where frequent calibration such as once per minute were not feasible.

Harrington, Richard F.↗
NASA NTRS2006

A Parametric Design Tool for Large Space Telescope Sunshields

In what follows, we describe the thermal-mechanical model, the thermo-optical properties assumed for the components, and the environment which influences the thermal performance. Following this, we present predictions of performance sensitivity to variation in some of the optical characteristics. Studies of the performance sensitivity are continuing, to inform the direction of technology investment for further development of capabilities for large space telescopes.

SAFIR↗
DOE OSTI2019

Imaging Individual Barium Atoms in Solid Xenon for Barium Tagging in nEXO

The search for neutrinoless double beta decay probes the fundamental properties of neutrinos, including whether or not the neutrino and antineutrino are distinct. Double beta detectors are large and expensive, so background reduction is essential for extracting the highest sensitivity. The identification, or “tagging”, of the 136Ba daughter atom from double beta decay of 136Xe provides a technique for eliminating backgrounds in the nEXO neutrinoless double beta decay experiment. The tagging scheme studied in this work utilizes a cryogenic probe to trap the barium atom in solid xenon, where the barium atom is tagged via fluorescence imaging in the solid xenon matrix. Here we demonstrate imaging and counting of individual atoms of barium in solid xenon by scanning a focused laser across a solid xenon matrix deposited on a sapphire window. When the laser sits on an individual atom, the fluorescence persists for ~30 s before dropping abruptly to the background level, a clear confirmation of one-atom imaging. No barium fluorescence persists following evaporation of a barium deposit to a limit of =0.16%. This is the first time that single atoms have been imaged in solid noble element. It establishes the basic principle of a barium tagging technique for nEXO.

Chambers, C↗
DOE OSTI2020

Shock initiation of cyclotol (75/25) at both ambient temperature and 70 °C

Here, six shock initiation experiments have been carried out to study the shock sensitivity and develop the unreacted Hugoniot for the Cyclotol composition 75/25 %wt RDX/TNT. The experiments were carried out both at ambient temperature, and elevated to 70 °C, close to the TNT melt temperature of 80 °C. Two sets of three experiments were fired at nominal pressures of 4.1, 6.0 and 7.7 GPa. Comparison has been made to the previously studied (80/20 %wt RDX/TNT) composition and analysis shows that the five percent decrease in RDX content has resulted in a significant increase in shock sensitivity. The increase in initial temperature has yielded an unexpectedly small increase in shock sensitivity, particularly relative to the effects of the compositional change. Wave profiles will be presented, along with a discussion of the unreacted Hugoniot and relative sensitivities presented in the Pop plot.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS1998

Computation of the Effects of Inhomogeneous Clouds on Retrieval of Remotely Sensed Properties

Current and future earth observation programs depend on satellite measurements of radiance to retrieve the properties of clouds on a global basis. At present, this retrieval is made assuming that the clouds in the instrument field of view are plane parallel and independent of adjacent pixels. While this assumption is known to be false except in very limited cases, its impact can be evaluated, and if possible corrected, based on emerging theoretical techniques. In this study, the Spherical Harmonic Discrete Ordinate Method (SHDOM, Evans, 1996) has been used to assess the sensitivity of the retrieval to a variety of cloud parameters. SHDOM allows the plane parallel assumption to be relaxed and makes 2D and even 3D radiative solutions practical. A previous study (Chambers et al., 1996) assessed the effect of horizontal inhomogeneity in 45 LANDSAT scenes of boundary layer clouds over ocean. The four scenes studied here represent overcast, broken, scattered and strongly thermally forced cloud fields and are used to perform sensitivity studies to a wider variety of parameters. Comparisons are made at three solar zenith angles (theta (sub 0) = 0, 49, and 63 degrees) to avoid ambiguity in the results due to solar zenith angle.

Chambers, Lin H.↗
NASA NTRS1990

Computational aspects of sensitivity calculations in linear transient structural analysis

A study was performed focusing on the calculation of sensitivities of displacements, velocities, accelerations, and stresses in linear, structural, transient response problems. One significant goal of the study was to develop and evaluate sensitivity calculation techniques suitable for large-order finite element analyses. Accordingly, approximation vectors such as vibration mode shapes are used to reduce the dimensionality of the finite element model. Much of the research focused on the accuracy of both response quantities and sensitivities as a function of number of vectors used. Two types of sensitivity calculation techniques were developed and evaluated. The first type of technique is an overall finite difference method where the analysis is repeated for perturbed designs. The second type of technique is termed semi-analytical because it involves direct, analytical differentiation of the equations of motion with finite difference approximation of the coefficient matrices. To be computationally practical in large-order problems, the overall finite difference methods must use the approximation vectors from the original design in the analyses of the perturbed models. In several cases this fixed mode approach resulted in very poor approximations of the stress sensitivities. Almost all of the original modes were required for an accurate sensitivity and for small numbers of modes, the accuracy was extremely poor. To overcome this poor accuracy, two semi-analytical techniques were developed. The first technique accounts for the change in eigenvectors through approximate eigenvector derivatives. The second technique applies the mode acceleration method of transient analysis to the sensitivity calculations. Both result in accurate values of the stress sensitivities with a small number of modes and much lower computational costs than if the vibration modes were recalculated and then used in an overall finite difference method.

Greene, William H.↗
NASA NTRS1987

X-ray selected high redshift clusters of galaxies

Studies of the evolution of X-ray emission from clusters of galaxies have so far used distant clusters discovered optically and then observed at X-ray wavelengths (Henry et al., 1982; Henry and Lavery, 1984). A different approach to the study of cluster evolution is to use clusters selected directly by their X-ray emission, since X-ray selection is extremely successful at discovering high-redshift clusters (up to z = 0.5). The Extension of the Medium Sensitivity Survey, a study of serendipitous X-ray sources discovered with the Einstein Imaging Proportional Counter, has so far provided a sample of more than 60 clusters with relatively high redshifts. Upon completion of the identification programs the sample will include over 100 clusters. Here the data currently available are presented, and the basic properties of this new sample of clusters of galaxies are discussed. A preliminary number-counts distribution is also derived.

Gioia, Isabella M.↗
NASA NTRS1991

Disinfection susceptibility of waterborne pseudomonads and Legionellae under simulated space vehicle conditions

The sensitivity of waterborne bacteria from iodinated systems to iodine is examined with particular attention to the recovery of the organisms. The use of iodine as a disinfectant for space-vehicle water is described, and references are made to studies of iodine sensitivity and the relationship between growth rate and iodine sensitivity. Growth following iodination is discussed, and bacterial responses to nutrient restriction are examined for both P aeruginosa and Legionella pneumophila. The low level of organic nutrients in spacecraft water allows the selection for bacteria that are less sensitive to halogens. The formation of biofilms within the water-treatment system enhances bacterial resistance to iodine, and in the case of high-quality water it is shown that sublethal doses of iodine can stimulate bacterial growth. Water treatment should therefore be based on antecedent growth conditions, nutrient limitation, biofilm formation, and ambient selective pressures.

Mcfeters, Gordon A.↗
DOE OSTI2014

An Assessment of Supercritical CO2 Power Cycles Integrated with Generic Heat Sources (Presentation)

Presentation for the 4th sCO2 Symposium Presentation (2014). Presented is a detailed analysis of the supercritical CO2 (sCO2) recompression Brayton cycle to better understand at a fundamental level the dependence of the cycle performance on operating conditions. The focus of this study is on cycle performance, particularly efficiency. No cost estimates were performed. However, a number of indirect measures of cycle cost were examined to provide an indication of whether the operating conditions were in a region of great cost sensitivity. In this study, a sCO2 recompression cycle is described and a set of baseline operating conditions proposed. The heat source for the study was considered generic or agnostic. No temperature value, temperature range, or heat flux was assumed to limit cycle design.

Generic heat source↗
DOE OSTI2014

An Assessment of Supercritical CO2 Power Cycles Integrated with Generic Heat Sources (Report)

Paper for the 4th sCO2 Symposium. (2014). This paper documents a detailed analysis of the supercritical CO2 (sCO2) recompression Brayton cycle to better understand at a fundamental level the dependence of the cycle performance on operating conditions. The focus of this study is on cycle performance, particularly efficiency. No cost estimates were performed. However, a number of indirect measures of cycle cost were examined to provide an indication of whether the operating conditions were in a region of great cost sensitivity. In this study, a sCO2 recompression cycle is described and a set of baseline operating conditions proposed. The heat source for the study was considered generic or agnostic. No temperature value, temperature range, or heat flux was assumed to limit cycle design.

Generic heat source↗
DOE OSTI2013

Sensitivity analysis of synergistic collaborative scenarios towards sustainable nuclear energy systems

The paper presents results of the study on the role of collaboration among countries towards sustainable global nuclear energy systems. The study explores various market shares for nuclear fuel cycle services, possible scale of collaboration among countries and assesses benefits and issues relevant for collaboration between suppliers and users of nuclear fuel cycle services. The approach used in the study is based on a heterogeneous world model with grouping of the non-personified nuclear energy countries according to different nuclear fuel cycle policies. The methodology applied in the analysis allocates a fraction of future global nuclear energy generation to each of such country-groups as a function of time. The sensitivity studies performed show the impacts of the group shares on the scope of collaboration among countries and on the resulting possible reactor mix and nuclear fuel cycle infrastructure versus time. The study quantitatively demonstrates that the synergistic approach to nuclear fuel cycle has a significant potential for offering a win-win collaborative strategy to both, technology holders and technology users on their joint way to future sustainable nuclear energy systems. The study also highlights possible issues on such a collaborative way. (authors)

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2020

A Comparative Study of Two BAM Designs for Friction Sensitivity Testing of Explosives

A new commercial design of BAM friction tester that utilizes a programmable servo motor was tested in comparison to the traditional cam-driven model. Displacement and velocity profiles were analyzed for both designs; significant differences were found between the two designs, most notable of which is that the traditional cam-driven unit has plate velocities that can be 50–75 % greater than those seen on the servo-driven model. Five energetic materials were also tested on each machine, including PETN, RDX, HMX, CL-20, and HNAB. Finally, results from the servo-driven model generally showed slightly less sensitivity when compared to the cam driven model, though the magnitude of the difference is not significant enough to require modification of safe handling procedures for the materials tested.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
NASA NTRS1986

Contrast-Sensitivity Research

Report presents study of visual effects of frequencies of luminance patterns and particularly how frequency components affect visibilty of spatial phase differences over several octaves. Of interest to researchers engaged in development of algorithms relating to visual processing in robots, incorporation of human factors in design of visual displays, and development of set of rules visual system uses to reconstruct three-dimensional perception from two-dimensional neural representation.

Lawton, T. A.↗
NASA NTRS1992

First Lunar Outpost crew module thermal protection design sensitivity

A thermal protection study was conducted on the first lunar outpost (FLO) crew module. The study objectives are as follows: (1) assess effects of vehicle size on aerothermodynamic environment and thermal protection system (TPS) weight; (2) assess effects of lunar-return strategies on aerothermodynamic environment and TPS weight; and (3) assess weight penalty for common TPS design for all lunar-return strategies. All material is covered in viewgraph format.

Bouslog, Stan↗

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