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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS2010

Applying Monte Carlo Simulation to Launch Vehicle Design and Requirements Analysis

This Technical Publication (TP) is meant to address a number of topics related to the application of Monte Carlo simulation to launch vehicle design and requirements analysis. Although the focus is on a launch vehicle application, the methods may be applied to other complex systems as well. The TP is organized so that all the important topics are covered in the main text, and detailed derivations are in the appendices. The TP first introduces Monte Carlo simulation and the major topics to be discussed, including discussion of the input distributions for Monte Carlo runs, testing the simulation, how many runs are necessary for verification of requirements, what to do if results are desired for events that happen only rarely, and postprocessing, including analyzing any failed runs, examples of useful output products, and statistical information for generating desired results from the output data. Topics in the appendices include some tables for requirements verification, derivation of the number of runs required and generation of output probabilistic data with consumer risk included, derivation of launch vehicle models to include possible variations of assembled vehicles, minimization of a consumable to achieve a two-dimensional statistical result, recontact probability during staging, ensuring duplicated Monte Carlo random variations, and importance sampling.

Hanson, J. M.↗
NASA NTRS2016

Hydrogen Isotopic Composition of Apatite in Northwest Africa 7034: A Record of the "Intermediate" H-Isotopic Reservoir in the Martian Crust?

Northwest Africa (NWA) 7034 and its pairings comprise a regolith breccia with a basaltic bulk composition [1] that yields a better match than any other martian meteorite to visible-infrared reflectance spectra of the martian surface measured from orbit [2]. The composition of the fine-grained matrix within NWA 7034 bears a striking resemblance to the major element composition estimated for the martian crust, with several exceptions. The NWA 7034 matrix is depleted in Fe, Ti, and Cr and enriched in Al, Na, and P [3]. The differences in Al and Fe are the most substantial, but the Fe content of NWA 7034 matrix falls within the range reported for the southern highlands crust [6]. It was previously suggested by [4] that NWA 7034 was sourced from the southern highlands based on the ancient 4.4 Ga ages recorded in NWA 7034/7533 zircons [4, 5]. In addition, the NWA 7034 matrix material is enriched in incompatible trace elements by a factor of 1.2-1.5 [7] relative to estimates of the bulk martian crust. The La/Yb ratio of the bulk martian crust is estimated to be approximately 3 [7], and the La/Yb of the NWA 7034 matrix materials ranges from approximately 3.9 to 4.4 [3, 8], indicating a higher degree of LREE enrichment in the NWA 7034 matrix materials. This elevated La/Yb ratio and enrichment in incompatible lithophile trace elements is consistent with NWA 7034 representing a more geochemically enriched crustal terrain than is represented by the bulk martian crust, which would be expected if NWA 7034 represents the bulk crust from the southern highlands. Given the similarities between NWA 7034 and the martian crust, NWA 7034 may represent an important sample for constraining the composition of the martian crust, particularly the ancient highlands. In the present study, we seek to constrain the H isotopic composition of the martian crust using Cl-rich apatite in NWA 7034. Usui et al., [9] recently proposed that a H isotopic reservoir exists within the martian crust that has a H-isotopic composition that is intermediate (δD of 1000-2000per mille) between an isotopically light mantle (Delta D is less than 275per mille [10]) and an isotopically heavy atmosphere (δD of 2500-6100per mille [11, 12]). Apatites in NWA 7034 occur in a number of lithologic domains, however apatites across all lithologic domains have been affected by a Pb-loss event at about 1.5 Ga before present [5], so they are unlikely to have retained a primary composition and are more likely to have equilibrated with fluids within the martian crust that may or may not have exchanged with the martian atmosphere. Equilibration of apatite with crustal fluids is further supported by the chlorine-rich compositions exhibited by apatites in NWA 7034 in comparison to apatites from other martian meteorites (Figure 1; [13]). Cl is more hydrophilic than F, which promotes formation of Cl-rich apatite compositions in fluid-rich systems [e.g., 14, 15-17].

McCubbin, F. M.↗
NASA NTRS2016

H-Isotopic Composition of Apatite in Northwest Africa 7034

Northwest Africa (NWA) 7034 and its pairings comprise a regolith breccia with a basaltic bulk composition [1] that yields a better match than any other martian meteorite to estimates of Mars' bulk crust composition [1]. Given the similarities between NWA 7034 and the martian crust, NWA 7034 may represent an important sample for constraining the crustal composition of components that cannot be measured directly by remote sensing. In the present study, we seek to constrain the H isotopic composition of the martian crust using Cl-rich apatite in NWA 7034.

McCubbin, F. M.↗
NASA NTRS2019

A Diversity of Calcium-Rich Carbonates in EETA 79001

Carbonate minerals of martian origin are present in several martian meteorites in trace concentrations (less than 1 percent) and possess unique isotopic signatures that suggest that the martian environment and/or isotopic reservoirs are very different from the Earth’s. Carbonates are most common in the older martian meteorites (ALH 84001 and the nakhlites), however, there have been reports of carbonate in the younger shergottites including EETA 79001 (Mars meteorite Elephant Moraine 79001). Acidification studies of Zagami and Shergotty have shown that CO2 is released suggesting that carbonate phases are present in these meteorites, but the origin of these phases is controversial. The young ages of the shergottites makes them important samples for understanding the modern martian environment. The carbonates in EETA 79001 are the best-characterized secondary minerals in a shergottite, but their origin remains controversial. Gooding et al. argued that two types of carbonate occur with-in the glassy parts of the meteorite. One type, nearly pure CaCO3 associated with Ca-sulfate shows textural evidence for being present in the rock prior to it being shocked, suggesting formation on Mars. The second was more abundant and consists of Ca-rich carbonate, possibly with finely intergrown Mg-phosphate, but does not possess any textural relationships indicative of a martian origin. Carbon and oxygen isotopic studies of this carbonate yielded oxygen isotopes that potentially suggest a martian origin as well

Niles, P. B.↗
NASA NTRS2020

Mineralogy and Petrology of Fine-Grained Calcium-Aluminum-Rich Inclusions from the Reduced CV3 Chondrite Thiel Mountains 07007

Calcium-Aluminum-rich inclusions (CAIs) are among the oldest Solar System solids, and studies of these objects have played an essential role in developing an understanding of chemical and physical processes that initiated and characterized key events related to the Solar System’s formation and evolution. CAIs occur as μm- to cm-sized inclusions in chondritic meteorites, particularly in carbonaceous chondrites, and consist of various refractory silicate and oxide phases (e.g., melilite, spinel, Al-Ti-rich diopside, hibonite, and corundum) that are predicted by thermodynamic models to be among the first solids to con-dense from a cooling gas of solar composition. Fine grained CAIs (FGIs) are important samples to probe volatility-driven condensation processes in the solar nebula, because they have escaped thermal processes (e.g., melting) experienced by coarse-grained CAIs. In order to explore the primary nebular history of FGIs, a detailed mineralogical and petrologic study is necessary. In this research effort, we constrained the mineralogy and petrology of two CAIs 07-10 and -11 from the reduced CV3 chondrite Thiel Mountains (TIL) 07007, with the aim of evaluating their provenance as nebular condensates.

Anderkin, C. J.↗
NASA NTRSDate not supplied

Adaptive Stress Testing of Trajectory Predictions in Flight Management Systems

To find failure events and their likelihoods in flight-critical systems, we investigate the use of an advanced black-box stress testing approach called adaptive stress testing. We analyze a trajectory predictor from a developmental commercial flight management system which takes as input a collection of lateral waypoints and en-route environmental conditions. Our aim is to search for failure events relating to inconsistencies in the predicted lateral trajectories. The intention of this work is to find likely failures and report them back to the developers so they can address and potentially resolve shortcomings of the system before deployment. To improve search performance, this work extends the adaptive stress testing formulation to be applied more generally to sequential decision-making problems with episodic reward by collecting the state transitions during the search and evaluating at the end of the simulated rollout. We use a modified Monte Carlo tree search algorithm with progressive widening as our adversarial reinforcement learner. The performance is compared to direct Monte Carlo simulations and to the cross-entropy method as an alternative importance sampling baseline. The goal is to find potential problems otherwise not found by traditional requirements-based testing. Results indicate that our adaptive stress testing approach finds more failures and finds failures with higher likelihood relative to the baseline approaches.

adaptive stress testing↗
NASA NTRS2022

Evidence for a Significant Kuiper Belt Dust Contribution to the Zodiacal Cloud

Interplanetary dust particles (IDPs) are important samples of dust-producing objects in the solar system including many primitive and organic-rich bodies that are not sampled by known meteorites. IDPs spiral in towards the Sun under the influence of Poynting-Robertson (P-R) drag forces and are exposed to solar energetic particles (SEPs) that leave tracks of ionization damage in anhydrous silicate grains. We determined the exposure ages of track-rich IDPs using a new calibration of the SEP track production rate and show that track-rich IDPs have long exposure ages (>1 My) that preclude an origin from main-belt asteroids (MBAs) and Jupiter-family comets (JFCs). We propose that track-rich IDPs represent samples of dust produced by collisions among Edgeworth-Kuiper Belt objects (EKBOs) and that appreciable amounts of EKBO dust are contributing to the Zodiacal cloud. Many track-rich IDPs also contain abundant secondary minerals that provide direct evidence for past aqueous activity on some EKBOs.

Lindsay P. Keller↗
DOE OSTI2018

The Earth Microbiome Project and Global Systems Biology

Recently, we published the first large-scale analysis of data from the Earth Microbiome Project (1, 2), a truly multidisciplinary research program involving more than 500 scientists and 27,751 samples acquired from 43 countries. These samples represent myriad specimen types and span a wide range of biotic and abiotic factors, geographic locations, and physicochemical properties. The database (https://qiita.ucsd.edu/emp/) is still growing, with over 90,000 amplicon datasets, >500 metagenomic runs, and metabolomics datasets from a similar number of samples. Importantly, the techniques, data and analytical tools are all standardized and publicly accessible, providing a framework to support research at a scale of integration that just 7 years ago seemed impossible.

Gilbert, Jack A.↗
DOE OSTI2022

Tensor networks for High Energy Physics: contribution to Snowmass 2021

Tensor network methods are becoming increasingly important for high-energy physics, condensed matter physics and quantum information science (QIS). We discuss the impact of tensor network methods on lattice field theory, quantum gravity and QIS in the context of High Energy Physics (HEP). These tools will target calculations for strongly interacting systems that are made difficult by sign problems when conventional Monte Carlo and other importance sampling methods are used. Further development of methods and software will be needed to make a significant impact in HEP. We discuss the roadmap to perform quantum chromodynamics (QCD) related calculations in the coming years. The research is labor intensive and requires state of the art computational science and computer science input for its development and validation. We briefly discuss the overlap with other science domains and industry.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

A Comparison of the FW-CADIS and MR-CADIS Variance Reduction Methods

The Consistent Adjoint Driven Importance Sampling (CADIS) method, which uses an adjoint deterministic estimate for making variance reduction parameters that optimize Monte Carlo (MC) shielding calculations, was introduced in 1998. This method was designed to optimize a single tally, typically an integrated response such as a detector count rate or a dose rate. Because both deterministic and stochastic methods are employed, CADIS is referred to as a hybrid method. In 2007, the forward-weighted CADIS (FW-CADIS) method was introduced to optimize several tallies at once, giving more uniform relative uncertainties among the tallies for both high-flux and low-flux areas of the problem. This method can be used for several small detectors, for semi-global problems (mesh tally over a large fraction of the problem), or for global problems (mesh tally over the entire problem). Optimization can be done for an integrated response such as a dose rate D(r) as a function of position, the total flux {phi}(r) as a function of position, or the space/energy flux {phi}(r,E). Both the CADIS and FW-CADIS methods have been in the MAVRIC sequence of SCALE for three versions (6.0 in 2009, 6.1 in 2011, and 6.2 in 2016). The ADVANTG package released in 2015 uses the CADIS and FW-CADIS methods to accelerate MCNP neutron/photon shielding calculations. In 2014, the multi-response CADIS (MR-CADIS) method was presented as a way to obtain even more uniform relative uncertainties for problems with multiple tallies than those obtained with FW-CADIS. The method does not use a forward deterministic calculation but instead uses one adjoint calculation for every tally to be optimized in the Monte Carlo calculation. This work compares the above methods.

42 ENGINEERING↗
DOE OSTI2018

Evaluating importance maps for TRIPOLI-4{sup R} using deterministic or on-line methods - 25446

Variance reduction is a key ingredient for solving radiation-protection problems with Monte-Carlo particle-transport codes. Many variance-reduction methods require the definition of an importance map and exhibit optimal performance if the importance map is given by the adjoint flux, the solution of the adjoint Boltzmann equation. This paper presents the implementation of the Consistent Adjoint-Driven Importance Sampling (CADIS) methodology via a coupling between the TRIPOLI-4 R Monte-Carlo particle-transport code and the IDT deterministic solver, Additionally, we describe the implementation of a new TRIPOLI-4 R score that makes it possible to estimate the adjoint flux during a direct Monte-Carlo calculation. These new features are expected to simplify the solution of difficult shielding problems. (authors)

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2022

Application of Monte Carlo code SHIFT for MSBR dose rate calculations

This paper presents a study that applied the Monte Carlo code SHIFT to calculate the radiological environment within a detailed Molten Salt Breeder Reactor (MSBR) model. It represents one of the first applications of the SHIFT code in stand-alone simulations for non-light water reactors to help demonstrate the code's potential uses in the design, licensing, and operation of advanced reactors. The radiological conditions of the MSBR were modeled when the reactor is at two different operation modes: normal full power and a drained state. The Forward Weighted-Consistent Adjoint Driven Importance Sampling (FW-CADIS) hybrid method in SHIFT was applied successfully to calculate the ex-core neutron and gamma dose rates for the MSBR at full power. Neutron and gamma dose rates within the drain cell were also calculated for the MSBR at the drained state by integrating the source terms obtained from an ORIGEN-S depletion calculation into the SHIFT simulation. The results indicate that in the drained state, the delayed gammas from the depleted fuel salt are the main contributors to the dose rates. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2025

The Profiled Feldman-Cousins Method for Confidence Interval Construction for the Nova 3-Flavor Oscillation Analysis

The small interaction cross-section of neutrinos makes experimental neutrino physics particularly responsive to technological advancements. A significant development leveraged by the NOvA experiment is large-scale parallel processing, enabling novel computational approaches to longstanding experimental challenges. Central to managing the resulting high-throughput data is NOvA’s implementation of the Freight Train model, designed for efficient data production and handling.This dissertation details the methodology and execution of the NOvA 2024 3-Flavor Oscillation Analysis, supported by a comprehensive dataset spanning ten years. It emphasizes frequentist results refined through the Feldman-Cousins (FC) technique, specifically addressing confidence interval corrections in parameter estimation. The computational intensity associated with Feldman-Cousins arises from extensive Monte Carlo simulations, which were substantially mitigated through parallel computing on the Perlmutter supercomputer at the National Energy Research Scientific Computing Center (NERSC), employing the MPI framework.To further enhance computational efficiency, an Importance Sampling method is introduced and evaluated, demonstrating significant potential to reduce complexity, particularly in exploring extreme parameter space regions. This thesis presents both the successful application of advanced computational resources and the development of sophisticated statistical techniques, aiming to enhance the precision and scope of neutrino oscillation analyses.

Dye ajdye11190@gmail.com, Andrew Joseph [Mississip↗
NASA NTRS2018

The Importance of Mars Samples in Constraining the Geological and Geophysical Processes on Mars and the Nature of Its Crust, Mantle, and Core

In situ compositional and mineralogical measurements on the Martian surface, combined with analyses of Martian meteorites, indicate that most igneous rocks are lavas and volcaniclastic rocks of basaltic composition and cumulates of ultramafic composition. Alkaline rocks are common in Early Hesperian terranes and tholeiitic rocks dominate younger Amazonian martian meteorites. Very uncommon feldspathic rocks represent the ultimate fractionation products, while granitoid rocks have not been identified. The impact-driven delivery mechanism for the Martian meteorites biases in favor of more competent samples - young, igneous rocks - and against rocks that are more representative of the Martian crust. Comparisons of rock types found among the meteorites to those documented by landed missions demonstrates this bias unequivocally; furthermore, of the over 100 martian lithologies represented by the martian meteorites, only one (NWA 7034 and pairs) is a regolith breccia.

Source record↗
NASA NTRS2019

Generating Excitement and Increasing Awaressness of NASA Planetary Science and Astromaterials Assets

Students, educators, the public, and the scientific community are so often inspired by NASA science and exploration. Millions have joined NASA during live mission event broadcasts and also follow NASA on social media. Exploration of worlds in our solar system enable the scientific community to obtain and analyze data that provide clues to better understand the history and evolution of our solar system. Missions that collect and return samples to Earth from a target solar system body provide scientists with samples they can research and analyze in their laboratories. For those who are not planetary scientists, they may not understand the significance of these samples and/or the importance of sample return missions. The Astromaterials Research and Exploration Science (ARES) Science Engagement team, through work supported by NASA’s Science Mission Directorate (SMD) Science Education Cooperative Agreement Notice NNH15ZDA004C, provides access to samples from NASA’s Astromaterials Collections through NASA sponsored exhibits at educator and scientific conferences, NASA relevant public outreach events, and collaborations with other Science Activation Teams supported by the SMD Cooperative Agreement Notice. The goal of this work is to generate excitement while enhancing knowledge and awareness of NASA’s unique assets, thus highlighting NASA planetary science and exploration.

Graff, P. V.↗
NASA NTRS2000

Reduction of Sample Rotation in Electrostatic Levitation

In many containerless processing systems, control of sample rotation is an important issue. Sample rotation is even more important for microgravity containerless processing systems, where the centrifugal acceleration can approach 1 g for even a small rotation rate. Prior work on rotation control by Rhim focused on driving the sample rotation at a controlled rate for droplet dynamics experiments and measurement of electrical conductivity. His technique allows controlled, fast rotation, but for many microgravity experiments the goal is zero rotation. To minimize sample rotation, two approaches are apparent: first, to identify and balance or eliminate the driving forces for undesired sample rotation, or second, implement a feedback-based rotation control loop in parallel with the position control loop. In this work, we have taken the first approach. To minimize sample rotation, the simplest approach is to identify and balance or eliminate the driving forces for undesired sample rotation. Our experiments show that the dominant driving force for rotation of machined Zr spheres in the MSFC ESL is photon pressure from the heating laser. Experimental results showing the correlation between heating power and torque are compared to theoretical predictions, and a strategy for minimizing the torque due to photon pressure is presented.

Hyers, R. W↗
NASA NTRS1991

A perception and manipulation system for collecting rock samples

An important part of a planetary exploration mission is to collect and analyze surface samples. As part of the Carnegie Mellon University Ambler Project, researchers are investigating techniques for collecting samples using a robot arm and a range sensor. The aim of this work is to make the sample collection operation fully autonomous. Described here are the components of the experimental system, including a perception module that extracts objects of interest from range images and produces models of their shapes, and a manipulation module that enables the system to pick up the objects identified by the perception module. The system was tested on a small testbed using natural terrain.

Choi, T.↗