Results for “Perspective” — Page 26

NASA NTRS2020

Strategic Perspectives on the Future of Systems Engineering at NASA

NASA’s Model-Based Systems Engineering (MBSE) Infusion and Modernization Initiative (MIAMI) chartered a strategy group comprising early to mid-career NASA subject matter experts with diverse experiences to look into the future of systems engineering at NASA. The purpose of the group was to provide a vision for the future state of systems engineering practices and to develop a strategic plan to enable the evolution of the art up to 20 years in the future. The group used a design thinking approach to gather ideas and obtained insight into current engineering processes and domain outlook by interviewing engineers of varying expertise and experiences who had worked on teams of different sizes for missions large and small. The group built a roadmap to highlight future needs, projected capabilities, and technology and competency gaps and developed a strategic plan to ensure the expedient introduction of these capabilities. The resulting strategic plan recommends capability development and workforce strategies and provides guidance for Agency-wide SE policy. Artifacts, details, and raw data from the strategy team’s work are contained in NASA/TM-20205002911/SUPPL, Strategic Perspectives on the Future of Systems Engineering at NASA: Supplemental Information: Appendixes A to K.

Anupa R Bajwa↗

NASA NTRS2019

Satellite Ocean Colour: Current Status and Future Perspective

Spectrally resolved water-leaving radiances (ocean colour) and inferred chlorophyll concentration are key to studying phytoplankton dynamics at seasonal and inter-annual scales, for a better understanding of the role of phytoplankton in marine biogeochemistry; the global carbon cycle; and the response of marine ecosystems to climate variability, change and feedback processes. Ocean colour data also have a critical role in operational observation systems monitoring coastal eutrophication, harmful algal blooms, and sediment plumes. The contiguous ocean-colour record reached 21 years in 2018; however, it is comprised of a number of one-off missions such that creating a consistent time-series of ocean-colour data requires merging of the individual sensors (including MERIS, Aqua-MODIS, SeaWiFS, VIIRS, and OLCI) with differing sensor characteristics, without introducing artefacts. By contrast, the next decade will see consistent observations from operational ocean colour series with sensors of similar design and with a replacement strategy. Also, by 2029 the record will start to be of sufficient duration to discriminate climate change impacts from natural variability, at least in some regions. This paper describes the current status and future prospects in the field of ocean colour focusing on large to medium resolution observations of oceans and coastal seas. It reviews the user requirements in terms of products and uncertainty characteristics and then describes features of current and future satellite ocean-colour sensors, both operational and innovative. The key role of in situ validation and calibration is highlighted as are ground segments that process the data received from the ocean-colour sensors and deliver analysis-ready products to end-users. Example applications of the ocean-colour data are presented, focusing on the climate data record and operational applications including water quality and assimilation into numerical models. Current capacity building and training activities pertinent to ocean colour are described and finally a summary of future perspectives is provided.

ocean colour↗

NASA NTRS2021

Solving Two-Equation Turbulence Models With a Perspective on Solving Transport Equations

There are three principal objectives of this report. The first objective is to investigate frequently used two-equation models when solving the RANS equations. In this study, we consider the 2006Wilcox and the 2003 Menter Shear Stress Transport (SST) models. Also, a simple change of the Wilcox model is introduced to improve computational predictions for transonic flows. Computations for flows over two different airfoils are examined to compare these turbulence models. Effects on modeling the physics of each flow due to variations in the models, such as using either strainrate or vorticity in the turbulence production term, are considered and discussed. The second objective of this report is to not only explore but also evaluate the performance of the solution algorithm for the mean flow and the transport equations. The RANS and turbulence modeling equations aresolved in a weakly coupled manner with a diagonal implicit Runge-Kutta (DIRK) solution algorithm. Throughout this report, emphasis is given to reducing the residuals to machine zero in all flow calculations, so as to eliminate the error due to numerical integration of the discrete governing equations. The final objective is to provide a perspective on solving transport equations for turbulence modeling. Aspects of solving such stiff systems of equations, as well as various numerical difficulties and possible techniques to overcome them, are considered. Discussion is also provided concerning what is called ’numerical compatibility’, which is an essential requirement when designing a solution algorithm for solving transport equations.

turbulence modeling↗

NASA NTRSDate not supplied

AAM Ecosystem Aircraft Working Group: Pilot's Perspective

NASA’s Urban Air Mobility (UAM) Sub-Project is engaged in research to support the introduction of air taxis into the National Airspace System. This presentation is for an AAM Ecosystem Working Group presentation on the pilot's perspective about flying an air taxi or flying a conventional aircraft in the same airspace as an air taxi. It introduces the aircraft and operating environment and includes questions for a pilot panel and the audience.

aeronautics↗

NASA NTRS2022

Climate Change Penalty and Benefit on Surface Ozone: A Global Perspective Based on CMIP6 Earth System Models

This work presents an analysis of the effect of climate change on surface ozone discussing the related penalties and benefits around the globe from the global modelling perspective based on simulations with five CMIP6 (Coupled Model Intercomparison Project Phase 6) Earth System Models. As part of AerChemMIP (Aerosol Chemistry Model Intercomparison Project) all models conducted simulation experiments considering future climate (ssp370SST) and present-day climate (ssp370pdSST) under the same future emissions trajectory (SSP3-7.0). A multi-model global average climate change benefit on surface ozone of −0.96 ± 0.07 ppbv °C−1 is calculated which is mainly linked to the dominating role of enhanced ozone destruction with higher water vapour abundances under a warmer climate. Over regions remote from pollution sources, there is a robust decline in mean surface ozone concentration on an annual basis as well as for boreal winter and summer varying spatially from −0.2 to −2 ppbv °C−1, with strongest decline over tropical oceanic regions. The implication is that over regions remote from pollution sources (except over the Arctic) there is a consistent climate change benefit for baseline ozone due to global warming. However, ozone increases over regions close to anthropogenic pollution sources or close to enhanced natural biogenic volatile organic compounds emission sources with a rate ranging regionally from 0.2 to 2 ppbv C−1, implying a regional surface ozone penalty due to global warming. Overall, the future climate change enhances the efficiency of precursor emissions to generate surface ozone in polluted regions and thus the magnitude of this effect depends on the regional emission changes considered in this study within the SSP3_7.0 scenario. The comparison of the climate change impact effect on surface ozone versus the combined effect of climate and emission changes indicates the dominant role of precursor emission changes in projecting surface ozone concentrations under future climate change scenarios.

surface ozone↗

NASA NTRS2022

Perspective - Solid Oxide Cell Technology for Space Exploration

To enable long-term manned space exploration, there are critical needs in oxygen and water for life support, electrical power for on-board operation, and in situ generation of propellants for ascent vehicles. Low temperature electrochemical devices have been developed and utilized for on-board oxygen and power generation in several manned space programs. High temperature solid oxide cell technology offers unique advantages for future space missions. This perspective highlights recent advances in solid oxide cell technology that make it feasible for adoption in aerospace applications and outlines the projected needs in future research and development to better support space exploration

solid oxide↗

NASA NTRS2022

Perspective on Satellite-Based Land Data Assimilation to Estimate Water Cycle Components in an Era of Advanced Data Availability and Model Sophistication

The beginning of the 21st century is marked by a rapid growth of land surface satellite data and model sophistication. This offers new opportunities to estimate multiple components of the water cycle via satellite-based land data assimilation (DA) across multiple scales. By resolving more processes in land surface models and by coupling the land, the atmosphere, and other Earth system compartments, the observed information can be propagated to constrain additional unobserved variables. Furthermore, access to more satellite observations enables the direct constraint of more and more components of the water cycle that are of interest to end users. However, the finer level of detail in models and data is also often accompanied by an increase in dimensions, with more state variables, parameters, or boundary conditions to estimate, and more observations to assimilate. This requires advanced DA methods and efficient solutions. One solution is to target specific observations for assimilation based on a sensitivity study or coupling strength analysis, because not all observations are equally effective in improving subsequent forecasts of hydrological variables, weather, agricultural production, or hazards through DA. This paper offers a perspective on current and future land DA development, and suggestions to optimally exploit advances in observing and modeling systems.

Data Assimilation↗

NASA NTRS2022

Coevolution of Machine Learning and Process-Based Modelling to Revolutionize Earth and Environmental Sciences: A Perspective

Machine learning (ML) applications in Earth and environmental sciences (EES) have gained incredible momentum in recent years. However, these ML applications have largely evolved in ‘isolation’ from the mechanistic, process-based modelling (PBM) paradigms, which have historically been the cornerstone of scientific discovery and policy support. In this perspective, we assert that the cultural barriers between the ML and PBM communities limit the potential of ML, and even its ‘hybridization’ with PBM, for EES applications. Fundamental, but often ignored, differences between ML and PBM are discussed as well as their strengths and weaknesses in light of three overarching modelling objectives in EES, (1) nowcasting and prediction, (2) scenario analysis, and (3) diagnostic learning. The paper ponders over a ‘coevolutionary’ approach to model building, shifting away from a borrowing to a co-creation culture, to develop a generation of models that leverage the unique strengths of ML such as scalability to big data and high-dimensional mapping, while remaining faithful to process-based knowledge base and principles of model explainability and interpretability, and therefore, falsifiability.

Saman Razavi↗

NASA NTRSDate not supplied

Lessons Learned With Risk Management: A Systems Engineer's Perspective

Risk management is a communications device that, when executed as an essential task, enables systems engineering to effectively balance risk across the project. Developing and baselining risks is an essential continuous task to ensure top project concerns both from bottom up and top down are being mitigated. Risk management provides the opportunity to avoid the consequence of the risk when mitigation steps start early enough. Just discussing risk with all the project flight elements during development, even if no risks are open, provides an excellent communication opportunity between systems engineering and those elements, ensuring concerns and worries have a platform for discussion. A well-managed risk identification process will identify concerns that are serious but not being clearly communicated, and it will enable mitigation of those potential problems before they cause a failure. Effective risk management requires considerable time and effort, but that effort will save time and money across the development. Risk management must be frequent enough to be useful and in depth enough to bring out emerging issues. It also requires a trusting relationship between the lead systems engineer and element and/or subsystem leads. The discussions need to be with the right number of individuals (typically a handful) and the right duration in time (typically an hour a month). Outside of these risk working groups, there is a formal management process to input, status, and disposition risks, and a monthly Risk Management Board meeting where key project stakeholders are informed. This paper provides good guidance on effective risk management from a systems engineering perspective and provides project lessons learned from the NASA spaceflight missions NICER, Landsat 9, LRO, and OSIRIS-REx to demonstrate the effectiveness of risk management.

Lessons Learned↗

NASA NTRSDate not supplied

Lessons Learned With Risk Management: A Systems Engineer’s Perspective

Risk management is a communications device that, when executed as an essential task, enables systems engineering to effectively balance risk across the project. Developing and baselining risks is an essential continuous task to ensure top project concerns both from bottom up and top down are being mitigated. Risk management provides the opportunity to avoid the consequence of the risk when mitigation steps start early enough. Just discussing risk with all the project flight elements during development, even if no risks are open, provides an excellent communication opportunity between systems engineering and those elements, ensuring concerns and worries have a platform for discussion. A well-managed risk identification process will identify concerns that are serious but not being clearly communicated, and it will enable mitigation of those potential problems before they cause a failure. Effective risk management requires considerable time and effort, but that effort will save time and money across the development. Risk management must be frequent enough to be useful and in depth enough to bring out emerging issues. It also requires a trusting relationship between the lead systems engineer and element and/or subsystem leads. The discussions need to be with the right number of individuals (typically a handful) and the right duration in time (typically an hour a month). Outside of these risk working groups, there is a formal management process to input, status, and disposition risks, and a monthly Risk Management Board meeting where key project stakeholders are informed. This paper provides good guidance on effective risk management from a systems engineering perspective and provides project lessons learned from the NASA spaceflight missions NICER, Landsat 9, LRO, and OSIRIS-REx to demonstrate the effectiveness of risk management.

Lessons Learned↗

NASA NTRSDate not supplied

A Regional Perspective on Global NWP from North America and Recent Developments in the NASA GEOS System

Satellite data have played an important role in improving model forecast skills. This presentation will give a perspective of data usages of vital satellites on global NWP and show some examples of using existing satellite observations in the GEOS data assimilation system at NASA GMAO. The efforts to utilize emerging satellite data and to prepare for the upcoming new instruments NASA supports will be presented as well.

Yanqiu Zhu↗

NASA NTRSDate not supplied

Spacecraft Window Design from a Thermal Perspective

This paper gives a rudimentary introduction to spacecraft window design from a thermal engineering perspective. Windows have always been integral parts of all of NASA’s flown, crewed spacecraft missions and will continue to be included on future crewed vehicles. They are part of the primary structure and require high structural reliability. Often neglected by non-thermal engineers, there are important thermal impacts to including windows on a spacecraft design. Thermal radiation from the sun, planetary bodies, or other vehicles can enter the vehicle and heat the interior. Windows can also be heat leaks to space during cold operations. Windows may also serve as part of the vehicle Thermal Protection System for entry vehicles. Like all other parts of the spacecraft, windows must be included in thermal models to predict temperatures; the transparency of pane materials and the addition of coatings increase modeling complexity. Testing of windows is also more complex than typical spacecraft structure due to the uniqueness of each pane (depending on material), transmittance, and the challenge of physically measuring window material temperature during testing.

Cheyn L Worn↗

NASA NTRS2024

A Perspective on Multi-Source Energy Harvesting Technology Using Piezoelectric and Thermoelectric Materials

Energy harvesting using various locally available energy sources such as vibration energy, heat, sound, or magnetic field have become attractive topics for supplying power to modular electronic devices making them run independently in extreme environments. In this paper, we will be discussing the perspectives on thermoelectric (TE) and piezoelectric materials and devices, and then the concept of multi-source energy harvester using piezoelectric and thermoelectric devices and integration of them into a reliable and independent power source. TE materials having low thermal conductivity and high figure-of-merit ( zT ) are developed to convert even a small temperature gradient efficiently into electrical energy with the state-of-the-art conversion efficiency of ~15% and output power of ~56 W from single device. The piezoelectric device architecture is configured using high performance piezoelectric ceramics (Cu-Mn-PIN-PMN-PT). These ceramics exhibit high piezoelectric coefficient with high mechanical quality factor and low dielectric loss factor. Using these piezoelectric materials, power density as high a 2 mW/cm 2 is demonstrated in 1-1.5 g vibration environments. The piezoelectric device is attached on the surface of TE module to capture both the vibration and thermal energy sources to realize dual mode energy harvester. The multi-energy transfer strategy opens opportunities for a future generation of wireless and modular electronic devices. These devices would be useful in powering wearable electronic devices, micro sensor chargers, etc. in extreme environmental conditions using body heat/thermal sources and induced motion/vibrations.

Piezoelectric↗

NASA NTRSDate not supplied

Spacecraft Window Design From A Thermal Perspective

This paper gives a rudimentary introduction to spacecraft window design from a thermal engineering perspective. Windows have always been integral parts of all of NASA’s flown, crewed spacecraft missions and will continue to be included on future crewed vehicles. They are part of the primary structure and require high structural reliability. Often neglected by non-thermal engineers, there are important thermal impacts to including windows on a spacecraft design. Thermal radiation from the sun, planetary bodies, or other vehicles can enter the vehicle and heat the interior. Windows can also be heat leaks to space during cold operations. Windows may also serve as part of the vehicle Thermal Protection System for entry vehicles. Like all other parts of the spacecraft, windows must be included in thermal models to predict temperatures; the transparency of pane materials and the addition of coatings increase modeling complexity. Testing of windows is also more complex than typical spacecraft structure due to the uniqueness of each pane (depending on material), transmittance, and the challenge of physically measuring window material temperature during testing.

Thermal↗

DOE OSTI2019

Identification of Critical Airports from the Perspective of Delay and Disruption Propagation in Air Travel Networks

It is well-known that delays and disruptions that originate at certain airports end up spreading spread on the network to other airports, sometimes straining a large fraction of the system. Hence data-driven modeling of this phenomenon is important from the standpoint of planning and strategy. In this work, utilizing the publicly available data from the Federal Aviation Administration (FAA), we employ the well-known influence maximization paradigm, to mine for the top airports in the US airport network, from the perspective of delay spread. In the process, we develop a diffusion simulator and implement a greedy algorithm to aid our task. We then explore the temporal trends by considering one winter month and one summer month in our analysis. Finally, we characterize the clusters in the US airport network and investigate the patterns of delay spread when airports in each of the clusters are affected.

Visweswara Sathanur, Arun↗

DOE OSTI2021

Scenarios of a Sustainable Energy Transition: Perspectives from the U.S.

The energy sector has been undergoing a significant transition over the past decade, which was accelerated in 2020 during the COVD-19 pandemic. This presentation provides an overview of energy trends in the U.S., including electricity, oil and gas, coal, and renewables, the impact of the pandemic in 2020, and forecasts for recovery. Scenarios of energy use and future integrated technologies are outlined as near and mid-term approaches. The presentation concludes with potential U.S. policy priorities focused on energy and economic recovery, as well as perspectives on energy planning from the disruptions of 2020. The presentation is part of day-long series of presentations covering post-COVID-19 energy responses in Asia, Australia, Europe, and the United States.

COVID-19↗

DOE OSTI2023

Comparative Economic Analysis of Capture, Transport, and Storage from a CO2 Source Perspective

This presentation provides an overview of a study that evaluated multiple carbon capture and storage (CCS) networks within the Central United States using NETL-developed resources and models to assess management options different CO2 source types face from both economic and regional geologic perspectives when capturing, transporting and storing their CO2. It was presented at the Carbon Capture, Utilization, and Storage (CCUS) 2023 conference, organized and presented by the Society of Petroleum Engineers (SPE), American Association of Petroleum Geologists (AAPG), and Society of Exploration Geophysicists (SEG) and held in Houston, Texas, April 25-27, 2023.

Guinan, Allison↗

DOE OSTI2022

Carbon Storage and Utilization: Perspective on Water Usage and Opportunities

Disseminate technical and non-technical perspective on the opportunities for water recovery from produced water and CO2 storage in the I-WEST region. Concerned citizens and advocacy groups; farmers and ranchers; tribal, state, city, and county leaders; and project leaders working on water-related initiatives are all encouraged to participate in the workshop. This workshop is an opportunity for regional stakeholders to join the conversation about the challenges and opportunities water presents for energy transition in the Inter- Mountain West.

Vikara, Derek↗