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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 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Data Assimilation with Machine Learning Surrogate Models: A Case Study with FourCastNet

Modern data-driven surrogate models for weather forecasting provide accurate short-term predictions but inaccurate and nonphysical long-term forecasts. This paper investigates online weather prediction using machine learning surrogates supplemented with partial and noisy observations. We empirically demonstrate and theoretically justify that, despite the long-time instability of the surrogates and the sparsity of the observations, filtering estimates can remain accurate in the long-time horizon. As a case study, we integrate FourCastNet, a weather surrogate model, within a variational data assimilation framework using partial, noisy ERA5 data. Our results show that filtering estimates remain accurate over a year-long assimilation window and provide effective initial conditions for forecasting tasks, including extreme event prediction.

Adrian, Melissa [Univ. of Chicago, IL (United Stat↗
NASA NTRS1997

Formal Methods for Verification and Validation of Partial Specifications: A Case Study

This paper describes our work exploring the suitability of formal specification methods for independent verification and validation (IV&V) of software specifications for large, safety critical systems. An IV&V contractor often has to perform rapid analysis on incomplete specifications, with no control over how those specifications are represented. Lightweight formal methods show significant promise in this context, as they offer a way of uncovering major errors, without the burden of full proofs of correctness. We describe a case study of the use of partial formal models for V&V of the requirements for Fault Detection Isolation and Recovery on the space station. We conclude that the insights gained from formalizing a specification are valuable, and it is the process of formalization, rather than the end product that is important. It was only necessary to build enough of the formal model to test the properties in which we were interested. Maintenance of fidelity between multiple representations of the same requirements (as they evolve) is still a problem, and deserves further study.

Easterbrook, Steve↗
NASA NTRS1992

Strategic planning as a focus for continuous improvement. A case study

What do most of the successful people and organizations in our world have in common? Instead of worrying about the future, they work to create it. They have a plan, or a vision of what they want to accomplish and they focus their efforts on success. Strategic planning has been described as a disciplined, ongoing process to produce fundamental decisions and actions that shape what an organization is, what it does, and how it will respond to a changing environment. This case study discussion will evaluate the relationship between strategic planning and Total Quality Management (TQM), or continuous improvement, through the experience of the NASA Johnson Space Center in developing a strategy for the future. That experience clearly illustrates the value of strategic planning in setting the framework and establishing the overall thrust of continuous improvement initiatives. Equally significant, the fundamentals of a quality culture such as strong customer and supplier partnerships, participative involvement, open communications, and ownership were essential in overcoming the challenges inherent in the planning process. A reinforced management commitment to the quality culture was a clear, long-term benefit.

Oneill, John W.↗
NASA NTRS2012

Drought Monitoring for 3 North American Case Studies Based on the North American Land Data Assimilation System (NLDAS)

Both NLDAS Phase 1 (1996-2007) and Phase 2 (1979-present) datasets have been evaluated against in situ observational datasets, and NLDAS forcings and outputs are used by a wide variety of users. Drought indices and drought monitoring from NLDAS were recently examined by Mo et al. (2010) and Sheffield et al. (2010). In this poster, we will present results analyzing NLDAS Phase 2 forcings and outputs for 3 North American Case studies being analyzed as part of the NOAA MAPP Drought Task Force: (1) Western US drought (1998- 2004); (2) plains/southeast US drought (2006-2007); and (3) Current Texas-Mexico drought (2011-). We will examine percentiles of soil moisture consistent with the NLDAS drought monitor.

Peters-Lidard, Christa D.↗
DOE OSTI2024

Greater aperture counteracts effects of reduced stomatal density on WUE: a case study on sugarcane and meta-analysis

Stomata regulate CO 2 and water vapor exchange between leaves and the atmosphere. Stomata are a target for engineering to improve crop intrinsic water use efficiency (iWUE). One example is by expressing genes that lower stomatal density (SD) and reduce stomatal conductance (g sw ). However, the quantitative relationship between reduced SD, g sw , and the mechanisms underlying it is poorly understood. We addressed this knowledge gap using low-SD sugarcane (Saccharum spp. hybrid) as a case study alongside a meta-analysis of data from 10 species. Transgenic expression of EPIDERMAL PATTERNING FACTOR 2 from Sorghum bicolor (SbEFP2) in sugarcane reduced SD by 26-38% but did not affect gsw compared to wildtype. Further, no changes occurred in stomatal complex size or proxies for photosynthetic capacity. Measurements of gas exchange at low CO 2 concentrations that promote complete stomatal opening to normalize aperture size between genotypes were combined with modeling of maximum gsw from anatomical data. These data suggest that increased stomatal aperture is the only possible explanation for maintaining gsw when SD is reduced. Meta-analysis across C 3 dicots, C 3 monocots, and C 4 monocots revealed engineered reductions in SD are strongly correlated with lower gsw (r 2 =0.60-0.98), but this response is damped relative to the change in anatomy.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS1984

Some case studies of ocean wave physical processes utilizing the GSFC airborne radar ocean wave spectrometer

The NASA K sub u band Radar Ocean Wave Spectrometer (ROWS) is an experimental prototype of a possible future satellite instrument for low data rate global waves measurements. The ROWS technique, which utilizes short pulse radar altimeters in a conical scan mode near vertical incidence to map the directional slope spectrum in wave number and azimuth, is briefly described. The potential of the technique is illustrated by some specific case studies of wave physical processes utilizing the aircraft ROWS data. These include: (1) an evaluation of numerical hindcast model performance in storm sea conditions, (2) a study of fetch limited wave growth, and (3) a study of the fully developed sea state. Results of these studies, which are briefly summarized, show how directional wave spectral observations from a mobile platform can contribute enormously to our understanding of wave physical processes.

Jackson, F. C.↗
NASA NTRS1993

Electronic Performance Support for Operational Systems: A Case Study of the Link Monitor and Control Operator Assistant

For complex operational systems, help needs to come from the inside out. It is often not realistic to call a help desk for problems that need immediate attention, especially for tasks that put a heavy cognitive load on the system operator. This session addresses the issues associated with providing electronic performance support for operational systems, including situations where the system is already fielded and can only change through evolution rather than revolution. We present a case study based on our experiences in developing the Link Monitor and Control Operator Assistant for NASA's Deep Space Network (DSN). The goals of the Operator Assistant are to improve the operability of the system and increase the efficiency of mission operations.

Hill, Randall W., Jr.↗
NASA NTRS2009

Diameter Versus Mass in the Development of the Orion Life Support Umbilical: A Case Study in Systems Engineering

Systems engineering could also be called the art of compromise. At its heart, systems engineering seeks to find that solution which maximizes the utility of the system, usually compromising the performance of each individual subsystem. While seemingly straightforward, systems engineering methodology is complicated when the utility to be maximized is unclear and the costs to each individual subsystem are not - or not easily - quantifiable. In this paper, we explore one such systems engineering problem within the Constellation Program as a case study in applied systems engineering. During suited operations, astronauts within Orion will be connected to an umbilical to receive and return breathing gas. The pressure drop associated with this umbilical must be overcome by the Orion vehicle. A smaller umbilical, which is desirable for crew operations, means a higher pressure drop, resulting in additional mass and power for the vehicle. We outline the technical considerations in the development of this integrated system and discuss the method by which we reached the ultimate solution. This paper, while just one example of the kind of problem solving that happens every day, offers insight into what happens when the theories of systems engineering are put into practice.

Jordan, Nicole↗
NASA NTRS2011

A Debris Disk Case Study: 49 Ceti with Herschel

Gas-poor debris disks represent a fundamentally different class of circumstellar disk than gas-rich protoplanetary disks. Their gas probably originates from the same source as the dust, i.e. planetesimal destruction, but the low gas densities make it difficult to detect. So far, Herschel has detected far-IR gas emission from one debris disk, Beta Pictoris. Here I discuss a well-known debris disk system in the GASPS survey, 49 Ceti. It serves as a case study for modeling low-density gas in optically thin disks. The dust disk appears to be spatially resolved at 70 um. Most interestingly, there appears to be a hint of ClI 158 urn emission at the roughly 2 sigma level. Preliminary modeling suggests that reconciling the sub-mm CO emission from this system with the weak or non-existent far-IR atomic lines may require an unusual chemical composition in the gas of this disk.

Roberge, Aki↗
NASA NTRS1994

Results of ozone measurements in Northern Germany: A case study

At most of the German ozone recording stations which have records over a sufficiently long period, the results of the summer months of 1989 showed the highest values since the beginning of the measurements. One of the reasons for this phenomenon was the high duration of sunshine in that summer; for example, in Potsdam near Berlin in May 1989 the sunshine duration was the highest in May since the beginning of the records in 1893. For that reason we selected this summer for a case study. The basis for the study was mainly the ozone measuring stations of the network of Lower Saxony and the Federal Office of Environment (Umweltbundesamt). The results of these summer measurements point to intense sources of ozone, probably in form of gaseous precursors, in the Middle German industrial areas near Leipzig and Halle and in Northwestern Czechoslovakia, with coal-mining, chemical and petrochemical industries, coking plants and others. The maps of average ozone concentrations, number or days with high ozone maxima, ozone-windroses of the stations, etc., suggest that these areas could be a main source of precursors and of photochemical ozone production in summer smog episodes in Central Europe. Stations on the North Sea coast, at which early ozone measurements were made by our institute in 1973/74 are compared with similarly located stations of the Lower Saxon network in 1989 and the results show a reversal of the ozone-windroses. In 1973/74, the highest ozone concentrations were correlated with wind directions from the sea while in 1989 these concentrations were correlated with directions from the continent. In the recent years, photochemical ozone production on the continent is probably predominant, while in former years the higher ozone content of the maritime subpolar air masses has been explained by stratospheric-tropospheric exchange.

Schmidt, Manfred↗
DOE OSTI2026

Improving neutrino-nuclei interaction models: Recommendations and case studies on Peelle’s Pertinent Puzzle

Improving the modeling of neutrino-nuclei interactions using data-driven methods is crucial for high-precision neutrino oscillation experiments. This paper investigates Peelle’s Pertinent Puzzle (PPP) in the context of neutrino measurements, a longstanding challenge to fitting theoretical models to experimental data. Inconsistencies in data-model comparisons hinder efforts to enhance the accuracy and reliability of model predictions. We analyze various sources contributing to these inconsistencies and propose strategies to address them, supported by practical case studies. We advocate for incorporating model fitting exercises as a standard practice in cross section publications to enhance the robustness of results. We use a common analysis framework to explore PPP-related challenges with MicroBooNE and T2K data in an unified manner. Our findings offer valuable insights for improving the accuracy and reliability of neutrino-nuclei interaction models, particularly by systematically tuning models using data.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS1976

A comparison between conventional and LANDSAT based hydrologic modeling: The Four Mile Run case study

Models designed to support the hydrologic studies associated with urban water resources planning require input parameters that are defined in terms of land cover. Estimating the land cover is a difficult and expensive task when drainage areas larger than a few sq. km are involved. Conventional and LANDSAT based methods for estimating the land cover based input parameters required by hydrologic planning models were compared in a case study of the 50.5 sq. km (19.5 sq. mi) Four Mile Run Watershed in Virginia. Results of the study indicate that the LANDSAT based approach is highly cost effective for planning model studies. The conventional approach to define inputs was based on 1:3600 aerial photos, required 110 man-days and a total cost of $14,000. The LANDSAT based approach required 6.9 man-days and cost $2,350. The conventional and LANDSAT based models gave similar results relative to discharges and estimated annual damages expected from no flood control, channelization, and detention storage alternatives.

Ragan, R. M.↗
DOE OSTI2026

Providing Thermal Stability for an Exascale Supercomputer: A Case Study of Frontier's Cooling System

High performance computing (HPC) systems frequently produce large dynamic power swings, even under typical operating conditions, that can present a significant challenge for their direct-liquid cooling systems. Further, the primary cooling loops that must remove this waste heat have response times measured in minutes while the underlying HPC component thermal stress is measured in seconds. The per-socket power demand for both compute processing units (CPUs) and graphic processing units ( GPUs) continues to increase with each successive generation while case temperatures are declining. New HPC systems are expected to exacerbate the challenge of these dynamic power swings and the impact on effective and timely cooling systems. This paper describes the cooling and controls system for Oak Ridge National Laboratory’s Frontier Supercomputer, the first sustained exascale system, as a case study for this situation. The cooling and control system for Frontier demonstrates specific success, but with a number of trade-offs and decisions that suggest further design and operating optimizations for the community at large to consider.

42 ENGINEERING↗
NASA NTRS1988

Two gimbal bearing case studies: Some lessons learned

Two troublesome, torque related problems associated with gimbal actuators are discussed. Large, thin section angular contact bearings can have a surprisingly high torque sensitivity to radial thermal gradients. A predictive thermal-mechanical bearing analysis, as described, was helpful in establishing a safe temperature operating envelope. In the second example, end-of-travel torque limits of an oscillatory gimbal bearing appoached motor stall during limit cycling life tests. Bearing modifications required to restore acceptable torque performance are described. The lessons learned from these case studies should benefit designers of precision gimbals where singular bearing torque related problems are not uncommon.

Loewenthal, Stuart H.↗
DOE OSTI2024

Defining weather scenarios for simulation-based assessment of thermal resilience of buildings under current and future climates: A case study in Brazil

In response to increasingly severe weather conditions, optimization of building performance and investment provides an opportunity to consider co-benefits of thermal resilience during energy efficiency retrofits. This work aims to assess thermal resilience of buildings using building performance simulation to evaluate the indoor overheating risk under nine weather scenarios, considering historical (2010s), mid-term future (2050s), and long-term future (2090s) typical meteorological years, and heat wave years. Such an analysis is based on resilience profiles that combine six integrated indicators. A case study with a district of 92 buildings in Brazil was conducted, and a combination of strategies to improve thermal resilience was identified. Results reflect the necessity of planning for resilience in the context of climate change. This is because strategies recommended under current conditions might not be ideal in the future. Therefore, an adaptable design should be prioritized. Cooling energy consumption could increase by 48 % by the 2050s, while excessive overheating issues could reach 37 % of the buildings. Simple passive strategies can significantly reduce the heat stress. A comprehensive thermal resilience analysis should ultimately be accompanied by a thorough reflection on the stakeholders’ objectives, available resources, and planning horizon, as well as the risks assumed for not being resilient.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2025

Deploying advanced supervisory control strategies to small- and medium-sized commercial buildings: Case study and lessons learned

Deploying advanced supervisory control strategies (ASCSs) in small- and medium-sized commercial buildings (SMBs) is vital but faces two issues: (1) a lack of building control and communication infrastructure (BCCI) in SMBs and (2) the significant engineering efforts required to implement and configurate ASCSs. Despite hindering the large-scale adoption of ASCSs in SMBs, these issues have not been adequately explored in the literature, which tends to focus more on feasibility than scalability. This paper provides a comprehensive evaluation of these two issues through a case study of an occupied SMB in eastern Tennessee of the United States. Specifically, we design and implement a BCCI for the studied building with commercial off-the-shelf products to accommodate the needs for deploying ASCSs. Here, we then deploy two ASCSs—a rule-based setback control and a model predictive control (MPC)—with the BCCI and evaluate their performance throughout the summer of 2024. This study reveals that the main bottlenecks in establishing BCCIs for SMBs are the high initial cost (∼$56/m 2 ) and communication delays (up to 9 min). Additionally, the assessment of the two ASCSs indicates that the majority (∼75 %) of the engineering effort required for implementation and configuration is spent on model identification, debugging, and tuning.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
NASA NTRS1999

Nitrogen Oxides and Ozones from B-747 Measurements (NOXAR) during POLINAT 2 and SONEX: Overview and Case-Studies on Continental and Marine Convection

In the framework of the project POLINAT 2 (Pollution in the North Atlantic Flight Corridor) we measured NO(x) (NO and NO2) and ozone on 98 flights through the North Atlantic Flight Corridor (NAFC) with a fully automated system permanently installed aboard an in-service Swissair B-747 airliner in the period of August to November 1997. The averaged NO, concentrations both in the NAFC and at the U.S. east coast were similar to that measured in autumn 1995 with the same system. The patchy occurrence of NO(x), enhancements up to 3000 pptv over several hundred kilometers (plumes), predominately found over the U.S. east coast lead to a log-normal NO(x) probability density function. In three case-studies we examine the origins of such plumes by combining back-trajectories with brightness temperature enhanced (IR) satellite imagery, with lightning observations from the U.S. National Lightning Detection Network (NLDN) or with the Optical Transient Detector (OTD) satellite. For frontal activity above the continental U.S., we demonstrate that the location of NO(x) plumes can be well explained with maps of convective influence. For another case we show that the number of lightning flashes in a cluster of marine thunderstorms is proportional to the NO(x) concentrations observed several hundred kilometers downwind of the anvil outflows and suggest that lightning was the dominant source. From the fact that in autumn the NO, maximum was found several hundred kilometers off the U.S. east coast, it can be inferred that thunderstorms triggered over the warm Gulf Stream current are an important source for the regional upper tropospheric NO(x) budget in autumn.

Jeker, Dominique↗
NASA NTRS2003

Case Studies of Fatigue Life Improvement Using Low Plasticity Burnishing in Gas Turbine Engine Applications

Surface enhancement technologies such as shot peening, laser shock peening (LSP), and low plasticity burnishing (LPB) can provide substantial fatigue life improvement. However, to be effective, the compressive residual stresses that increase fatigue strength must be retained in service. For successful integration into turbine design, the process must be affordable and compatible with the manufacturing environment. LPB provides thermally stable compression of comparable magnitude and even greater depth than other methods, and can be performed in conventional machine shop environments on CNC machine tools. LPB provides a means to extend the fatigue lives of both new and legacy aircraft engines and ground-based turbines. Improving fatigue performance by introducing deep stable layers of compressive residual stress avoids the generally cost prohibitive alternative of modifying either material or design. The X-ray diffraction based background studies of thermal and mechanical stability of surface enhancement techniques are briefly reviewed, demonstrating the importance of minimizing cold work. The LPB process, tooling, and control systems are described. An overview of current research programs conducted for engine OEMs and the military to apply LPB to a variety of engine and aging aircraft components are presented. Fatigue performance and residual stress data developed to date for several case studies are presented including: * The effect of LPB on the fatigue performance of the nickel based super alloy IN718, showing fatigue benefit of thermal stability at engine temperatures. * An order of magnitude improvement in damage tolerance of LPB processed Ti-6-4 fan blade leading edges. * Elimination of the fretting fatigue debit for Ti-6-4 with prior LPB. * Corrosion fatigue mitigation with LPB in Carpenter 450 steel. *Damage tolerance improvement in 17-4PH steel. Where appropriate, the performance of LPB is compared to conventional shot peening after exposure to engine operating temperatures.

Prevey, Paul S.↗