Results for “admissibility” — Page 15

NASA NTRS2013

Stability of Menisci in Detached Bridgman Growth

Detached growth, also referred to as dewetted growth, is a Bridgman crystal growth process in which the melt is in contact with the crucible wall but the crystal is not. A meniscus bridges the gap between the top of the crystal and the crucible wall. The meniscus shape depends on the contact angle of the melt with the crucible wall, the growth angle of the melt with respect to the solidifying crystal, the gas pressure differential, the Weber number describing the rotation rate of the crucible, and the Bond number. Only some of the meniscus shapes are stable and the stability criterion is the sign of the second variation of the potential energy upon admissible meniscus shape perturbations. The effects of confined gas volumes above and below the melt and crucible rotation are evaluated. The analysis is applicable to the non-stationary case where the crystal radius changes during growth. Static stability maps (crystal radius versus pressure differential) are obtained for a series of Bond numbers, growth angles and Weber numbers. Also, the specific cases of Ge and InSb, in both terrestrial and microgravity conditions, are analyzed. Stability was found to depend significantly on whether the interior surface was considered to be microscopically rough or smooth, corresponding to pinned or unpinned states. It was also found that all meniscus shapes are statically stable in a microgravity environment.

Mazuruk, Konstantin↗

NASA NTRS2014

Effects of Retronasal Smelling, Variety and Choice on Appetite and Satiety

Four principal areas were investigated. Nasal Patency: Measure nasal tissue swelling and airflow in BR and compare this to PreBR baseline and PostBR recovery; Ask subjects to self‐assess nasal congestion at each test to compare with Astronaut self‐assessment. Odorant Identification: Measure subject's ability to recognize odorants obtained from food samples taken from FARU (Flight Analog Research Unit) menu and compare this with recognition of food odors not available on FARU; Compare subject assessed ratings of odorant intensity and food liking with nasal airflow measurements to determine effect of fluid shift on smell ability. Meal Acceptability: Determine the onset and progression of reported 'menu fatigue' during BR; Determine whether decreased nasal airflow or smell ability are factors in 'menu fatigue'. Daily Mood and Health: Record mood changes during study and compare with meal acceptability and smell ability. A change in smell ability is measured by tracking subject perception of 35 odorants from admission to the FARU through to dismissal.

Hunter, Jean↗

NASA NTRS2017

Characterizing the Survey Strategy and Initial Orbit Determination Abilities of the NASA MCAT Telescope for Geosynchronous Orbital Debris Environmental Studies

The NASA Orbital Debris Program Office (ODPO) recently commissioned the Meter Class Autonomous Telescope (MCAT) on Ascension Island with the primary goal of obtaining population statistics of the geosynchronous (GEO) orbital debris environment. To help facilitate this, studies have been conducted using MCAT's known and projected capabilities to estimate the accuracy and timeliness in which it can survey the GEO environment. A simulated GEO debris population is created and sampled at various cadences and run through the Constrained Admissible Region Multi Hypotheses Filter (CAR-MHF). The orbits computed from the results are then compared to the simulated data to assess MCAT's ability to determine accurately the orbits of debris at various sample rates. Additionally, estimates of the rate at which MCAT will be able produce a complete GEO survey are presented using collected weather data and the proposed observation data collection cadence. The specific methods and results are presented here.

Frith, J.↗

NASA NTRS2017

Characterizing the Survey Strategy and Initial Orbit Determination Abilities of the NASA MCAT Telescope for Geosynchronous Orbital Debris Environmental Studies

The NASA Orbital Debris Program Office (ODPO) recently commissioned the Meter Class Autonomous Telescope (MCAT) on Ascension Island with the primary goal of obtaining population statistics of the geosynchronous (GEO) orbital debris environment. To help facilitate this, studies have been conducted using MCAT's known and projected capabilities to estimate the accuracy and timeliness in which it can survey the GEO environment. A simulated GEO debris population is created and sampled at various cadences and run through the Constrained Admissible Region Multi Hypotheses Filter (CAR-MHF). The orbits computed from the results are then compared to the simulated data to assess MCAT's ability to determine accurately the orbits of debris at various sample rates. Additionally, estimates of the rate at which MCAT will be able produce a complete GEO survey are presented using collected weather data and the proposed observation data collection cadence. The specific methods and results are presented here.

Frith, James↗

NASA NTRS2024

Tracking Community Building in Open Science

Open Science is enabled by a vibrant community of researchers who regularly engage with the data, from its production to its organization, curation, archiving, dissemination, analysis, and publication. This presentation will examine community building in open science. The NASA Open Science Data Repository (OSDR) makes data available to the public following the FAIR (Findability, Accessibility, Interoperability, and Reusability) principles. OSDR takes open science further with the OS Analysis Working Groups (AWGs) that facilitate community development and promotion. The primary activity of each AWG is to establish and validate analytical processes to generate higher-order data from data housed in OSDR. There are a number of these groups on various topics, including the Animal AWG, Plant AWG, Microbial AWG, Multi-Omics AWG, AI/ML AWG, and the Ames Life Sciences Data Archive (ALSDA) AWG. The international volunteers participating in these AWGs come from academia, citizen science initiatives, industry, and government. They include researchers, principal investigators, professors, trained hobbyists, and students from various domains and disciplines. Anyone may request to join the AWGs, and membership requests are vetted monthly by the group organizers before granting admission. Core to membership is demonstrated expertise through records of training, integrity, work in the professed domain(s), and good community standing. Regular virtual meetings are held for each AWG, with a varying cadence depending on the group's needs and goals. AWG communities share their expertise in research including cutting edge tools, software, frameworks, data formats, and libraries accelerating research collectively. This collaborative approach helps community members cross technology gaps and identify emerging challenges. These diverse communities encompass a wide range of individuals hailing from various sectors within the Science Mission Directorate and beyond. They serve as a means to promote and enhance transparency, accessibility, and inclusion. An annual AWG Symposium brings contributors together in person. Participation in AWGs can be synchronous or asynchronous, with some groups performing most of their work in off hours. Participants gain valuable skills and connections that allow them to add value to their communities and new organizations that they join, resulting in an expanded return on investment for the space life science community. Open science is increasingly a federal mandate and initiatives like NASA's Transform to Open Science and instruments like the Decadal Survey of Biological and Physical Sciences in Space demonstrate the need to carefully consider best practices in this domain. Here, we present greater detail about the makeup and participation metrics of the various AWGs affiliated with OSDR and details of successful peer-reviewed publication campaigns.

Christina M Johnson↗

NASA NTRSDate not supplied

Tracking Community Building in Open Science

Open Science is enabled by a vibrant community of researchers who regularly engage with the data, from its production to its organization, curation, archiving, dissemination, analysis, and publication. This presentation will examine community building in open science. The NASA Open Science Data Repository (OSDR) makes data available to the public following the FAIR (Findability, Accessibility, Interoperability, and Reusability) principles. OSDR takes open science further with the OS Analysis Working Groups (AWGs) that facilitate community development and promotion. The primary activity of each AWG is to establish and validate analytical processes to generate higher-order data from data housed in OSDR. There are a number of these groups on various topics, including the Animal AWG, Plant AWG, Microbial AWG, Multi-Omics AWG, AI/ML AWG, and the Ames Life Sciences Data Archive (ALSDA) AWG. The international volunteers participating in these AWGs come from academia, citizen science initiatives, industry, and government. They include researchers, principal investigators, professors, trained hobbyists, and students from various domains and disciplines. Anyone may request to join the AWGs, and membership requests are vetted monthly by the group organizers before granting admission. Core to membership is demonstrated expertise through records of training, integrity, work in the professed domain(s), and good community standing. Regular virtual meetings are held for each AWG, with a varying cadence depending on the group's needs and goals. AWG communities share their expertise in research including cutting edge tools, software, frameworks, data formats, and libraries accelerating research collectively. This collaborative approach helps community members cross technology gaps and identify emerging challenges. These diverse communities encompass a wide range of individuals hailing from various sectors within the Science Mission Directorate and beyond. They serve as a means to promote and enhance transparency, accessibility, and inclusion. An annual AWG Symposium brings contributors together in person. Participation in AWGs can be synchronous or asynchronous, with some groups performing most of their work in off hours. Participants gain valuable skills and connections that allow them to add value to their communities and new organizations that they join, resulting in an expanded return on investment for the space life science community. Open science is increasingly a federal mandate and initiatives like NASA's Transform to Open Science and instruments like the Decadal Survey of Biological and Physical Sciences in Space demonstrate the need to carefully consider best practices in this domain. Here, we present greater detail about the makeup and participation metrics of the various AWGs affiliated with OSDR and details of successful peer-reviewed publication campaigns.

Christina M Johnson↗

NASA NTRS2025

Magnetic Resonance Imaging (MRI) to Assess Changes to Trabecular Microarchitecture (Trb µArch) of the Hip

BACKGROUND . Calculated loss rates in trabecular (Trb) volumetric bone mineral density (vBMD), in astronauts after return from 6-month long-duration (LD) spaceflight, are rapid relative to menopause-induced loss rates and could contribute to the observed lack of recovery. Perforations in the Trb bony struts, skeletal fragility and fractures [5] have been associated with the rapid rate of bone loss in women due to menopause. The more rapid loss rate observed in astronauts could be inducing similar, irreversible losses of trabecular connectivity as seen in cadaver studies of female skeletons. These changes are not detectable by DXA technology and would not be discovered in astronauts during scheduled, triennial DXA testing for primary osteoporosis. High-resolution-peripheral quantitative computed tomography (HR-pQCT) of the lower leg have detected losses in Trb vBMD (vBMD) and changes in Trb microarchitecture (µArch) in astronauts immediately following routine 6-month spaceflights and continuing in some individuals for 1 or more years postflight with no signs of recovery. Resolution of these microarchitectural changes by whole body QCT, especially in the deeply embedded hip bone, is prohibitive due to excessive and unsafe radiation exposures. While HR-pQCT has sufficient resolution to study Trb µArch at safe and lower radiation exposure testing is restricted only to the lower leg and wrist. Hence, a technology to detect detrimental changes to Trb µArch in astronauts, especially of the hip, is needed to inform type and timing of countermeasures to irreversible deficits (preflight, inflight and postflight). METHODS . This HRP-funded study (2023-2027) will verify the sensitivity of a protocol for MRI scanning (on a 3T Siemens Vida) to detect changes to hip Trb µArch in persons following spinal cord injury (SCI); skeletal immobilization below the spinal lesion will serve as an analog for non-weight-bearing during spaceflight. The study period has been extended by 1 yr due to delayed Richmond IRB approval in Y1. A 3T MRI protocol will characterize serial changes in hip Trb µArch in SCI patients from time of admission at the Richmond VA Medical Center to their scheduled annual exam 12-months later. SCI patients with age, sex, and physical characteristics like ISS astronauts will be consented. The ability of 3T MRI hip scan to discriminate loss of trabecular connectivity subjects with SCI will be compared to age- and sex-matched ambulatory controls. A comparison between HR-pQCT and MRI measurements at the ankle (distal tibia) of study subjects will also be performed. A modified DXA scan analysis (3D-Shaper) will also be verified as a potential method for monitoring concurrent changes in hip Trb bone over 12-month. SIGNIFICANCE . Deliverables: a surveillance method for assessing for irreversible losses of connectivity and how skeletal changes after LD spaceflight(s) would modify the terrestrial risk of primary osteoporosis.

Spinal Cord Injury↗

NASA NTRS2025

Magnetic Resonance Imaging (MRI) to Assess Changes to Trabecular Microarchitecture (Trb µArch) of the Hip

BACKGROUND . Calculated loss rates in trabecular (Trb) volumetric bone mineral density (vBMD), in astronauts after return from 6-month long-duration (LD) spaceflight, are rapid relative to menopause-induced loss rates and could contribute to the observed lack of recovery. Perforations in the Trb bony struts, skeletal fragility and fractures [5] have been associated with the rapid rate of bone loss in women due to menopause. The more rapid loss rate observed in astronauts could be inducing similar, irreversible losses of trabecular connectivity as seen in cadaver studies of female skeletons. These changes are not detectable by DXA technology and would not be discovered in astronauts during scheduled, triennial DXA testing for primary osteoporosis. High-resolution-peripheral quantitative computed tomography (HR-pQCT) of the lower leg have detected losses in Trb vBMD (vBMD) and changes in Trb microarchitecture (µArch) in astronauts immediately following routine 6-month spaceflights and continuing in some individuals for 1 or more years postflight with no signs of recovery. Resolution of these microarchitectural changes by whole body QCT, especially in the deeply embedded hip bone, is prohibitive due to excessive and unsafe radiation exposures. While HR-pQCT has sufficient resolution to study Trb µArch at safe and lower radiation exposure testing is restricted only to the lower leg and wrist. Hence, a technology to detect detrimental changes to Trb µArch in astronauts, especially of the hip, is needed to inform type and timing of countermeasures to irreversible deficits (preflight, inflight and postflight). METHODS . This HRP-funded study (2023-2027) will verify the sensitivity of a protocol for MRI scanning (on a 3T Siemens Vida) to detect changes to hip Trb µArch in persons following spinal cord injury (SCI); skeletal immobilization below the spinal lesion will serve as an analog for non-weight-bearing during spaceflight. The study period has been extended by 1 yr due to delayed Richmond IRB approval in Y1. A 3T MRI protocol will characterize serial changes in hip Trb µArch in SCI patients from time of admission at the Richmond VA Medical Center to their scheduled annual exam 12-months later. SCI patients with age, sex, and physical characteristics like ISS astronauts will be consented. The ability of 3T MRI hip scan to discriminate loss of trabecular connectivity subjects with SCI will be compared to age- and sex-matched ambulatory controls. A comparison between HR-pQCT and MRI measurements at the ankle (distal tibia) of study subjects will also be performed. A modified DXA scan analysis (3D-Shaper) will also be verified as a potential method for monitoring concurrent changes in hip Trb bone over 12-month. SIGNIFICANCE . Deliverables: a surveillance method for assessing for irreversible losses of connectivity and how skeletal changes after LD spaceflight(s) would modify the terrestrial risk of primary osteoporosis.

Risk Surveillance↗

DOE OSTI2023

Thermal Extraction and Delivery from Advanced Reactor Systems

This document presents preliminary thermodynamic analysis of thermal extraction and delivery from advanced nuclear reactors. Light-water, high temperature gas, sodium fast, and molten salt reactors are templated and analyzed for thermal extraction from nominal steam production conditions. Uncontrolled, controlled, and partial admission steam extraction methods are described and analyzed to show the differences in system impact from the various methods. Thermal delivery modeling results show comparisons that have become possible through the computational capabilities of the thermal delivery model. Due to the significant degrees of freedom of the problem, specific cases are used to compare the thermodynamic costs of heat transport using various heat transfer fluids. All this work is done using Modelica models, allowing for the future application of models in dynamic analyses beyond the steady-state calculations presented in this report. Appendices describe additional capabilities and methods that can help users analyze complex problems using HYBRID models developed in Modelica.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

DOE OSTI2024

Intake runner for gaseous fuel engine, system, and method

A gaseous fuel engine system includes a hydrogen fuel supply, an engine housing having an intake port extending to a cylinder, and an intake runner. The intake runner includes a valve mount attached to a conduit and having a valve mounting face, and a gaseous fuel admission valve is mounted upon the valve mounting face. A hydrogen fuel passage extends from the valve mount through the conduit and is oriented angularly to at least one of a clamping face of the intake runner or the valve mounting face. Related apparatus and methodology is also disclosed.

Singh, Jaswinder↗

DOE OSTI2025

Novel Synthesis and Characterization of Uranium-Zirconium Carbonitride by Direct Casting

UZrCN has exhibited thermophysical properties beneficial to high temperature reactor applications such as nuclear thermal rockets. The present work investigates a novel liquid phase synthesis method involving the admission of nitrogen gas during arc melting of uranium, zirconium, and carbon. Initial microstructural examinations using SEM indicated that the samples remain heterogenous with zirconium-rich cores in a uranium-rich matrix. Heterogeneity resulted from large differences in melting temperature of the major constituents and rapid solidification. Additional EDS, combustion analysis, and inert gas fusion analysis proved that the core regions have both uranium and zirconium and establish that carbon and nitrogen are retained during the fabrication process. XRD clarifies that the light elements did not form compounds with the uranium matrix but rather incorporated into the core region forming a sub-stoichiometric UZrCN. Heat treatment performed on equimolar U-Zr-C resulted in an increase in the homogenous phase present with an XRD pattern reflecting a ternary UZrCN despite small amounts of segregation in the final button.

36 - MATERIALS SCIENCE↗

DOE OSTI2025

A Theoretical Operational Model for Complex Experiments and its Invariance Theorems

We develop and systematize the Theoretical–Operational Model (TOM), a framework that treats preparation and measurement —including their operational residues— as intrinsic structures of physical theory. The central contribution is a principled geometric–algebraic organization of admissible operational deformations, formulated using quantum channels, renormalization-style flows, and information-geometric tools. Within this structure, operational residues and background processes are represented as effective morphisms attached to these operational components, whose invariants yield constraints on how theoretical parameters vary under specified classes of deformations. Illustrations drawn from muon–electron conversion, long-baseline neutrino oscillations, and quark–gluon-plasma phenomenology show how TOM maps operational effects into inferences about theoretical parameters, enables systematic cross-experimental comparisons, and stabilizes parameter estimation against defined deformation families. By embedding the operational layer—together with its residues—within a structured theoretical setting, TOM supports both theory testing and theory development, clarifying the conceptual relation between experimental realization and the physical quantities represented by the theory.

Pronskikh, Vitaly [Fermilab] (ORCID:00000002518174↗

DOE OSTI2025

On Uranium-Zirconium Carbonitride Formation by Direct Casting - A Novel Synthesis Study

UZrCN has exhibited thermophysical properties beneficial to high temperature reactor applications such as nuclear thermal rockets. The present work investigates a novel liquid phase synthesis method involving the admission of nitrogen gas during arc melting of uranium, zirconium, and carbon. Initial microstructural examinations using SEM indicated that the samples remain heterogenous with zirconium-rich cores in a uranium-rich matrix. Heterogeneity resulted from large differences in melting temperature of the major constituents and rapid solidification. Additional EDS, combustion analysis, and inert gas fusion analysis proved that the core regions have both uranium and zirconium and establish that carbon and nitrogen are retained during the fabrication process. XRD clarifies that the light elements did not form compounds with the uranium matrix but rather incorporated into the core region forming a sub-stoichiometric UZrCN. Heat treatment performed on equimolar U-Zr-C resulted in an increase in the homogenous phase present with an XRD pattern reflecting a ternary UZrCN despite small amounts of segregation in the final button.

36 - MATERIALS SCIENCE↗