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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

System Guidelines for EMC Safety-Critical Circuits: Design, Selection, and Margin Demonstration

Demonstration of required safety margins on critical electrical/electronic circuits in large complex systems has become an implementation and cost problem. These margins are the difference between the activation level of the circuit and the electrical noise on the circuit in the actual operating environment. This document discusses the origin of the requirement and gives a detailed process flow for the identification of the system electromagnetic compatibility (EMC) critical circuit list. The process flow discusses the roles of engineering disciplines such as systems engineering, safety, and EMC. Design and analysis guidelines are provided to assist the designer in assuring the system design has a high probability of meeting the margin requirements. Examples of approaches used on actual programs (Skylab and Space Shuttle Solid Rocket Booster) are provided to show how variations of the approach can be used successfully.

Lawton, R. M.↗

JSC Orbital Debris Website Description

Purpose: The website provides information about the NASA Orbital Debris Program Office at JSC, which is the lead NASA center for orbital debris research. It is recognized world-wide for its leadership in addressing orbital debris issues. The NASA Orbital Debris Program Office has taken the international lead in conducting measurements of the environment and in developing the technical consensus for adopting mitigation measures to protect users of the orbital environment. Work at the center continues with developing an improved understanding of the orbital debris environment and measures that can be taken to control its growth. Major Contents: Orbital Debris research is divided into the following five broad efforts. Each area of research contains specific information as follows: 1) Modeling - NASA scientists continue to develop and upgrade orbital debris models to describe and characterize the current and future debris environment. Evolutionary and engineering models are described in detail. Downloadable items include a document in PDF format and executable software. 2) Measurements - Measurements of near-Earth orbital debris are accomplished by conducting ground-based and space-based observations of the orbital debris environment. The data from these sources provide validation of the environment models and identify the presence of new sources. Radar, optical and surface examinations are described. External links to related topics are provided. 3) Protection - Orbital debris protection involves conducting hypervelocity impact measurements to assess the risk presented by orbital debris to operating spacecraft and developing new materials and new designs to provide better protection from the environment with less weight penalty. The data from this work provides the link between the environment defined by the models and the risk presented by that environment to operating spacecraft and provides recommendations on design and operations procedures to reduce the risk as required. These data also help in the analysis and interpretation of impact features on returned spacecraft surfaces. 4) Mitigation - Controlling the growth of the orbital debris population is a high priority for NASA, the United States, and the major space-faring nations of the world to preserve near-Earth space for future generations. Mitigation measures can take the form of curtailing or preventing the creation of new debris, designing satellites to withstand impacts by small debris, and implementing operational procedures ranging from utilizing orbital regimes with less debris, adopting specific spacecraft attitudes, and even maneuvering to avoid collisions with debris. Downloadable items include several documents in PDF format and executable software.and 5) Reentry - Because of the increasing number of objects in space, NASA has adopted guidelines and assessment procedures to reduce the number of non-operational spacecraft and spent rocket upper stages orbiting the Earth. One method of postmission disposal is to allow reentry of these spacecraft, either from orbital decay (uncontrolled entry) or with a controlled entry. Orbital decay may be achieved by firing engines to lower the perigee altitude so that atmospheric drag will eventually cause the spacecraft to enter. However, the surviving debris impact footprint cannot be guaranteed to avoid inhabited landmasses. Controlled entry normally occurs by using a larger amount of propellant with a larger propulsion system to drive the spacecraft to enter the atmosphere at a steeper flight path angle. It will then enter at a more precise latitude, longitude, and footprint in a nearly uninhabited impact region, generally located in the ocean.

Johnson, Nicholas L.↗

Design, Qualification, and On Orbit Performance of the CALIPSO Aerosol Lidar Transmitter

The laser transmitter for the CALIPSO aerosol lidar mission has been operating on orbit as planned since June 2006. This document discusses the optical and laser system design and qualification process that led to this success. Space-qualifiable laser design guidelines included the use of mature laser technologies, the use of alignment sensitive resonator designs, the development and practice of stringent contamination control procedures, the operation of all optical components at appropriately derated levels, and the proper budgeting for the space-qualification of the electronics and software.

Hovis, Floyd E.↗

Update on Activities Related to the Library of Graphite Microstructures

This report provides an overview and update of the ongoing efforts to create a comprehensive library of microstructures for nuclear graphite and carbon-based materials under consideration for nuclear applications. The library includes data on microstructural characterization of unirradiated graphite materials, a guide to the techniques used to analyze graphite (which complements the ASME guidelines and ASTM standards), a summary of characterization data for neutron-irradiated or oxidized material, and a compendium of microstructural information for carbon-based materials. These efforts are being conducted at various length scales for the filler and binder phases in graphite to better understand graphite’s local structure and property relationships. This report is a follow-up to the previous milestone report titled Report on initial development of a database of nuclear graphite characteristics based on microstructural characterization, ORNL/TM/-2023/2992, published in July 2023.The effort to develop the library of microstructures supports the US Department of Energy Office of Advanced Reactor Technologies program objectives of aiding the material selection, licensing, management, and core assessments of a graphite core by documenting the unirradiated microstructure of relevant grades or characterizing the microstructure’s evolution under the reactor environment. Additionally, this project aims to provide (1) information and guidelines for the characterizing of graphite and (2) a protocol to assess a nuclear graphite grade.

36 MATERIALS SCIENCE↗

Powering Progress: Increasing capacity for State Agency participation in the development of solar guidelines

This project supported State Fish and Wildlife Agencies (SFWAs) in their participation in an industry-led process to develop nationwide utility scale solar energy wildlife guidelines intended to mitigate the impacts of large-scale solar development on wildlife and natural habitats. Led by the Association of Fish and Wildlife Agencies (AFWA), the project focused on documenting and communicating SFWA priorities, providing logistical and technical support for state engagement, and disseminating early outcomes to promote adoption and use.

14 SOLAR ENERGY↗

Reliability and quality assurance on the MOD 2 wind system

The Safety, Reliability, and Quality Assurance (R&QA) approach developed for the largest wind turbine generator, the Mod 2, is described. The R&QA approach assures that the machine is not hazardous to the public or to the operating personnel, is operated unattended on a utility grid, demonstrates reliable operation, and helps establish the quality assurance and maintainability requirements for future wind turbine projects. The significant guideline consisted of a failure modes and effects analysis (FMEA) during the design phase, hardware inspections during parts fabrication, and three simple documents to control activities during machine construction and operation.

Mason, W. E. B.↗

Quartz Clock Oscillator Design and Analysis

Engineers at Sandia National Laboratories (SNL) have used quartz - based clock oscillators in various missions since the 1980s. As such, the design of these frequency control devices requires a high degree of reliability and producibility. The quartz clock oscillators designed at SNL have evolved over many years and are currently developed in house and fabricated using SNLs internal CMOS foundry. They are designed to operate in harsh environments, including temperature, radiation, shock and vibration. This report documents the methodology behind the design of quartz clock oscillators developed at SNL and includes an overview of quartz resonator technology and usage guidelines and a detailed overview of oscillator circuits.

42 ENGINEERING↗

Photovoltaic power conditioning subsystem: State of the art and development opportunities

Photovoltaic systems, the state of the art of power conditioning subsystem components, and the design and operational interaction between photovoltaic systems and host utilities are detailed in this document. Major technical issues relating to the design and development of power conditioning systems for photovoltaic application are considered; these include: (1) standards, guidelines, and specifications; (2) cost effective hardware design; (3) impact of advanced components on power conditioning development; (4) protection and safety; (5) quality of power; (6) system efficiency; and (7) system integration with the host utility. Theories of harmonic distortion and reactive power flow are discussed, and information about power conditioner hardware and manufacturers is provided.

Krauthamer, S.↗

TCL2 National Campaign Human Factors Brief

The Technology Capability Level-2 National Campaign (TCL2nc) was conducted at six different test-sites located across the USA, during May and June of 2017. The campaign resulted in over 240 data collection flights using 24 different aircraft and involving 23 flight crews. Flights not only varied in duration, but also in the environments and terrains over which they flew. The TCL2nc highlighted beyond visual line of sight (BVLOS) and altitude-stratified operations, and saw five partners bring their own, independently built, UAS Service Supplier (USS) for use during the flight tests. This document presents data collected during the TCL2nc that informs the 'Operator' section of the 'Requirements/Best Practices' from the UTM Technical Capability Matrix and Guidelines to Operate (Rios, version as of March 2017). A review of the data collected indicated that although teams were well qualified on paper (in terms of both completing training and having experience with flying UAS vehicles), greater consideration should be given to the unique perspectives and backgrounds of future UAS operators. Overall, teams looked at a variety of sources for information, including USS client-displays, and participants became more mindful of the need to be aware of other vehicles, highlighting the value of reporting information. Observations found that flight crews' time to respond to a UTM issue depended heavily on the team structure, communication efficiency, and crew procedures. These points are discussed in more detail below.

unmanned vehicles↗

NASA's UTM Research

The Technology Capability Level-2 National Campaign (TCL2nc) was conducted at six different test sites located across the USA, during May and June of 2017. The campaign resulted in over 250 data collection flights using 26 different aircraft and involving 23 flight crews. Flights not only varied in duration, but also in the environments and terrains over which they flew. The TCL2nc highlighted beyond visual line of sight (BVLOS) and altitude-stratified operations, and saw five partners bring their own, independently built, UTM Service Supplier (USS) for use during the flight tests. This document presents data collected during the TCL2nc that informs the 'Operator' section of the 'Requirements/Best Practices' from the UTM Technical Capability Matrix and Guidelines to Operate (Rios, version as of March 2017). A review of the data collected indicated that although teams were well qualified on paper (in terms of both completing training and having experience with flying UAS vehicles), greater consideration should be given to the unique perspectives and backgrounds of future UAS operators. Overall, teams looked at a variety of sources for information, including USS client-displays, and participants became more aware of the need to be aware of other vehicles, highlighting the value of reporting information. Observations found that flight crews' time to respond to a UTM issue depended heavily on the team structure, communication efficiency, and crew procedures.

Mercer, Joey↗

Biomedical programs operations plans

Operational guidelines for the space shuttle life sciences payloads are presented. An operational assessment of the medical experimental altitude test for Skylab, and Skylab life sciences documentation are discussed along with the operations posture and collection of space shuttle operational planning data.

Walbrecher, H. F.↗

Spacecraft Maximum Allowable Concentrations for Selected Airborne Contaminants

As part of its efforts to promote safe conditions aboard spacecraft, NASA requested the National Research Council (NRC) to develop guidelines for establishing spacecraft maximum allowable concentrations (SMACs) for contaminants, and to review SMACs for various spacecraft contaminants to determine whether NASA's recommended exposure limits are consistent with the guidelines recommended by the subcommittee. In response to this request, the NRC first developed criteria and methods for preparing SMACs for spacecraft contaminants, published in its 1992 report Guidelines for Developing Spacecraft Maximum Allowable Concentrations for Space Station Contaminants . Since then, the Subcommittee on Spacecraft Maximum Allowable Concentrations has been reviewing NASA's documentation of chemical-specific SMACs as described in the Introduction to this volume. This report is the third volume in the series Spacecraft Maximum Allowable Concentrations for Space Station Contaminants . The first volume was published in 1994 and the second in 1996.

National Research Council↗

Improving File System Performance by Striping

This document discusses the performance and advantages of striped file systems on the SGI AD workstations. Performance of several striped file system configurations are compared and guidelines for optimal striping are recommended.

Lam, Terance L.↗

Space shuttle program: Lightning protection criteria document

The lightning environment for space shuttle design is defined and requirements that the design must satisfy to insure protection of the vehicle system from direct and indirect effects of lightning are imposed. Specifications, criteria, and guidelines included provide a practical and logical approach to protection problems.

Source record↗

Carbon Conversion Technologies - NETL Techno-Economic Analysis Guidelines

This presentation was delivered as part of the Global CO2 Initiative and NETL sponsored workshop, 2022 CCU TEA and LCA Guidance - A Harmonized Approach. The presentation highlights the intent and content of forthcoming NETL guidance documents and toolsets on conducting techno-economic analysis on carbon conversion technologies. Specifically discussed are the "Performing a TEA for Carbon Conversion Technologies" guidance document, the "Cost Scaling Methodology Specific to Carbon Conversion Technologies," and brief highlights of upcoming work products.

Henry, Samuel↗

Avionics Radiation Hardness Assurance (RHA) Guidelines

Based on the need to develop and adopt timely and up-to-date guidance to ensure that natural space radiation environment threats do not compromise mission success, the NASA Engineering and Safety Center (NESC) was solicited to develop and publish guidance for deriving radiation hardness assurance (RHA) requirements and for evaluating avionics hardware elements with respect to total ionizing dose, total non-ionizing dose, and single event effects. This document contains the outcome of the NESC assessment.

Guidelines↗

Federal Metering Guidance

The Federal Metering Guidance documents the metering provisions in EO 13834, Efficient Federal Operations and other metering related statutory requirements. This document provides the meter-related reporting requirements for Federal agencies, specifies a method to verify the existence of currently installed building-level meters, provides guidelines on prioritizing the implementation of advanced energy and water meters, sets the schedule for agencies to update their five-year metering plans, provides the minimum requirements that agencies must meet when updating their five-year metering plans along with recommend elements for an effective plan.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Best practices in software development for robust and reproducible geoscientific models based on insights from the Global Carbon Budget's dynamic vegetation models

Computational models play an increasingly vital role in scientific research by enabling the numerical simulation of complex processes. Such models are also fundamental in geosciences. For instance, they offer critical insights into the impacts of global change on the Earth system today and in the future. Beyond their value as research tools, models are also software products and should therefore adhere to certain established software engineering standards. However, scientists are rarely trained as software developers, which can lead to potential deficiencies in software quality like unreadable, inefficient, or erroneous code. The complexity of models, coupled with their integration into broader workflows, also often makes it challenging to reproduce results, evaluate processes, and build upon them. In this paper, we review the state and current practices of the development processes of the state-of-the-art land surface models used by the Global Carbon Budget. We combine the experience of modelers from the respective research groups with the expertise of software engineers from tech companies to outline key principles and tools for improving software quality in research. We explore four main areas: (1) model testing and validation, (2) scientific, technical, and user documentation, (3) version control, continuous integration, and code review, and (4) the portability and reproducibility of workflows. Our review reveals that while modeling communities are incorporating many best practices, significant room for improvement remains in areas such as automated testing, automated documentation, and reproducibility. Therefore, we here identify and promote essential software engineering practices, including numerous examples of practices from within the community that can serve as guidelines for other models and could help streamline processes across the entire community. We conclude with an open-source example implementation of these principles, demonstrating portable and reproducible data flows, a continuous integration setup, and web-based visualizations. This example may serve as a practical resource for model developers, users, and all scientists engaged in scientific programming.

Gregor, Konstantin [Technical Univ. of Munich (Ger↗