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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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NASA NTRS2020

Guidance for Human Error Analysis (HEA)

NASA’s Human-Rating Requirements for Space Systems in NASA Procedural Requirements (NPR) 8705.2C requires Program Managers to conduct a human error analysis (HEA) for all mission phases. The purpose of the HEA is to enable programs to understand and manage potential catastrophic hazards that could be caused by human error, understand the relative risks and uncertainties within the system design, and influence decisions throughout the system lifecycle. This document provides guidance to NASA civil servants and contractors on how the Agency’s HEA requirement can be fulfilled.

Human Error Analysis; NASA Procedural Requirement;↗
NASA NTRS2019

Fabrication and Performance of NiCuCoFeMn High Entropy Alloy Nanopastes for Brazing Inconel 718

Overview: High entropy alloys (HEAs) are a class of metallic alloys consisting of 5 plus elemental components and have four core effects - 1. High mixing entropy - 2. Sluggish diffusion kinetics - 3. High lattice distortion - 4. Cocktail effect; Boron-free, silicon-free brazing materials for nickel superalloys to avoid brittle intermetallic and eutectic phase formation; Size-dependent melting point depression can eliminate the need for boron, silicon and other melting point depressants; A Ni-Mn-Fe-Co-Cu HEA with low solidus and liquidus temperatures (1080 °C and 1150 °C) was developed; Low solidus and liquidus temperatures of the HEA combined with the nanoscale melting point depression in this study; Bulk HEA fabricated by induction melting of elemental powders; HEA nanoparticles (NPs) fabricated by ball milling of the HEA micropowder; Inconel 718 was laser brazed in air using the HEA and bulk and NP performances are compared.

Bridges, Denzel↗
NASA NTRSDate not supplied

Human Error Analysis for Human-Rated Space Systems

Humans bring unique capabilities to space systems and contribute to mission success in a manner that cannot be matched by machines. Nevertheless, from time to time, human error can present a threat to system performance, and system designers must anticipate and manage this risk. NASA’s Human-Rating Requirements for Space Systems call for program managers to conduct a human error analysis (HEA) during system development but does not specify how to do this. In 2018, NASA’s Engineering and Safety Center asked the authors to develop a guidance document on HEA. The resulting position paper outlines a suggested method for HEA and makes it clear that error analysis is about identifying and mitigating problems at a system level, and not about finding fault with individuals. Error management strategies must be directed at error-producing conditions, thereby reducing the likelihood of human error, while retaining the positive contribution that humans make to system operations.

human error human-rated space↗
NASA NTRS2019

Microstructural and Mechanical Characterization of a Dispersion Strengthened Medium Entropy Alloy Produced Using Selective Laser Melting

High entropy alloys (HEAs) are an interesting new class of alloys which have been shown to exhibit both notable strength and ductility for a wide range of temperature and stresses. In addition, the remarkably small difference between the solvus and liquidus temperatures for many face centered cubic HEAs makes them an excellent candidate for selective laser melting fabrication. In this study, the microstructure and mechanical properties of a dispersion strengthened equiatomic NiCoCr alloy successfully produced using selective laser melting are explored. The effect laser speed, laser power, and powder recyclability have on final part density and microstructural segregation are analyzed through both x-ray diffraction and high resolution scanning electron microscopy. These results are further validated and compared to stable phase predictions produced using a commercially available high entropy alloy mobility database. Lastly, the tensile strengths resulting from different heat treatment pathways are detailed.

Smith, T. M.↗
NASA NTRSDate not supplied

Modeling and Trade Space for Fuel Cell Powered Aircraft

Hydrogen has gained significant traction in research as a potential carbon-neutral fuel for future aircraft propulsion. The focus of this paper is on the hydrogen-electric aircraft (HEA) propulsion system which is a highly integrated network of high-power electrical, mechanical, fluidic, cryogenic, and thermal management components. These systems require careful analysis to determine the most efficient and light-weight design that ultimately reduces carbon emissions and operating cost. Fuel cell and energy storage sizing and optimization will be major factors that contribute to the aircraft feasibility independent of hydrogen storage. This paper describes the framework and modeling approach for the analysis of hydrogen-electric aircraft (HEA) propulsion systems for a under the National Aeronautics and Space Administration (NASA) Commercially-viable Hydrogen Aircraft for Reduction of Greenhouse Emissions (CH 2 ARGE) Project. For the first time, the Electrical Power System – Sizing and Analysis Tool (EPS-SAT) is used to conduct the sizing and trade studies on the hydrogen-electric aircraft propulsion system.

Hydrogen Electric Aircraft↗
NASA NTRS1972

Lee-surface vortex effects over configurations in hypersonic flow.

The role of vortices in producing intense localized hea ting to the leeward regions of a variety of configurations is shown and discussed. From experimental results, flow-field models are proposed which account for the interaction of the vortex and the upper surface boundary layer; correlation of the heating is then possible for planar delta wings. Guidelines derived from these studies are offered which reduce the vortex-induced heating by appropriate shaping of configurations such as the space shuttle. Reynolds number is shown to exert a large influence on the magnitude and location of the induced heating.

Whitehead, A. H., Jr.↗
NASA NTRS1995

An analysis of the Antarctic Halogen Occultation Experiment trace gas observations

Analysis of the version 16 Halogen Occultation Experiment (HALOE) CH4 data shows that this long-lived trace gas is well correlated with potential vorticity (PV) computed from National Meteorological Center balanced winds. Analyzing late September and October 1992 data, we show that very low CH4 values are confined to the interior of a vortex edge defined by the maximum gradient in PV. The CH4 and HF time tendency is used to estimate the descent rate in the Antarctic vortex. After removing a component of the trend correlated with the HALOE sampling pattern, we compute the lower stratosphere vertical descent rates and net heaing rates in the spring Antarctic vortex. Our computations of the spring Antarctic vortex heating rates give -0.5 to -0.1 K/day. Over the winter season, the overall lower stratospheric descent rate averages about 1.8-1.5 km/month. These computations are in line with radiative transfer estimates of the heating and descent rate. The HALOE data thus appear to be consistent with the picture of an isolated lower stratospheric Antarctic vortex.

Schoeberl, Mark R.↗
NASA NTRS2000

A Workshop on High Energy Astrophysical for Amateur Astronomers

Amateur astronomers are, in general, an enthusiastic and dynamic group of individuals who can help greatly in astronomy public outreach and education programs. In the U.S., they outnumber professional astronomers by over a factor of ten. Over eighty amateur astronomers from all over the U.S. and abroad attended a unique workshop in Huntsville, Alabama in April of this year. Most attendees were provided with travel grants under the condition that they disseminate knowledge gained at the workshop to civic groups, astronomy clubs and science teacher groups in their home communities. Twelve lecturers were given over two days, primarily by active high-energy researchers from NASA-MSFC and NASA-GSFC. Funding for the workshop was provided by a variety of NASA-sponsored projects, offices within OSS and private funding sources. The workshop attendees were selected by the AAVSO, which also administered the funding for the workshop. This high-leverage educational and public outreach program was deemed to be highly successful and bodes well for similar, future workshops. Many of the participants have already begun to give public talks on HEA and GRBs.

Fishman, Gerald J.↗
NASA NTRS2003

Package for Interactive Analysis of Line Emission (Analysis of UV-X-Ray High-Resolution Emission Spectra)

PINTofALE is an IDL based package to analyze high-resolution grating spectra. The first version was made available to the public on 3 February 2001. Since then we have carried out numerous changes, and the current release is version 1.5, released on 9 October 2002. The changes include upgrades to handle higher versions of IDL, the new version of the CHIANTI database (v4), major enhancements in user-friendliness, improved handling of response matrices, the ability to handle 24-bit color, access to the Atomic Plasma Emission Database (APED), and beta releases of Markov Chain Monte Carlo (MCMC) based DEM fitting routines. Plans for the future include: inclusion of MCMC techniques in the fitting programs, enhanced graphics capabilities, an overhaul of the line and continuum database structure, and bug fixes. In September 2002, we hired a data analyst (LiWei Lin) to work on PINTofALE. Mr.Lin is concentrating on incorporating MCMC as well as simpler Monte-Carlo techniques, fast RMF convolution, etc., into the code base, as well as reviewing the existing documentation and searching for bugs. A detailed description of the package, together with fairly detailed documentation, example walks-throughs, and downloadable tar files, are available on-line from http://hea-www. harvard.edu/PINTofALE/

Kashyap, Vinay↗
NASA NTRS2003

Virtual Reality Training: "Cybersickness" and Effects on Sensorimotor Functions

The overall goal of this study is to examine the extent to which exposure to virtual reality (VR) systems produces motion sickness and disrupts sensorimotor functions. Two of the major problems in using VRs are: 1) potential "cybersickness", a form of motion sickness, and 2) maladaptive sensorimotor coordination following virtual environment (VE) training. It is likely that users will eventually adapt to any unpleasant perceptual experiences in a virtual environment. However the most critical problem for training applications is that sensorimotor coordination strategies learned in the VE may not be similar to the responses required in the real environment. This study will evaluate and compare responses to the two types of VR delivery systems (head-mounted display [HMD] and a dome-projection system [DOME]), two exposure duration periods (30 minutes or 60 minutes), and repeated exposures (3 sessions). Specific responses that we will examine include cybersickness severity and symptom patterns, and several sensorimotor functions (eye-hea.d and eye-head-hand coordination, and postural equilibrium). To date, all hardware and software acquisition, development, integration and testing has been completed. A database has been developed and tested for the input, management and storage of all questionnaire data. All data analysis scripts have been developed and tested. Data was collected from 20 subjects in a pilot study that was conducted to determine the amount of training necessary to achieve a stable performance level. Seven subjects are currently enrolled in the study designed to examine the effects of exposure to VE systems on postural control. Data has been collected from two subjects, and it is expected that the results from ten subjects will be presented.

Harm, Deborah L.↗
NASA NTRS2016

The lunar space communications architecture from the KARI-NASA joint study

This paper covers the lunar space communications architecture defined by the feasibility study jointly conducted by the KARI and NASA during October 2014 – April 2015. From the KARI perspective, a formalized space communications architecture, while crucial to its first lunar mission, the Korea Pathfinder Lunar Orbiter (KPLO), has many long-term ramifications to the entire lunar exploration program that the KARI will undertake during the next decade. To NASA, in spite of its multitude of lunar missions, past and present, taking another new, fresh look at the architecture with a newcomer, who can bring new ideas and concept, is a precious opportunity to address some important issues for the future lunar exploration.

Rew, Dong Young↗