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Your search keyword '"T. A. O’Brien"' showing total 25 results
Start Over Author "T. A. O’Brien" Publisher nasa center for aerospace information (casi)
25 results on '"T. A. O’Brien"'

3. Recommending Low-Cost Compact Space Environment and Space Weather Effects Sensor Suites for NASA Missions

Author

Yihua Zheng, Michael A. Xapsos, Insoo Jun, T. P. O’Brien, Linda Parker, Wousik Kim, Justin Likar, Joseph Minow, Thomas Y. Chen, and Douglas Rowland

Subjects
Space Sciences (General)
Abstract

As miniaturized spacecraft (e.g., cubesats and smallsats) and instrumentation become an increasingly indispensable part of space exploration and scientific investigations, it is important to understand their potential susceptibility to space weather impacts resulting from the sometimes volatile space environment. There are a multitude of complexities involved in how space environment interacts with different space hardware/electronics. Measurements of such impacts, however, have been lacking. Therefore, we recommend developing and/or procuring low-cost, low-power consumption, and compact sensor suites (mainly for space weather and impact purposes) and flying them on all future NASA (and, more generally, U.S) missions in order to measure and quantify space weather impacts, in addition to the main instrumentation.

Published
2022

4. An Overview of ARTMIP’s Tier 2 Reanalysis Intercomparison: Uncertainty in the Detection of Atmospheric Rivers and their Associated Precipitation

Author

A. B. Marquardt Collow, C. A. Shields, B. Guan, S. Kim, J. M. Lora, E. E. McClenny, K. Nardi, A. Payne, K. Reid, E. J. Shearer, R. Tomé, J. D. Wille, A. M. Ramos, I. V. Gorodetskaya, L. R. Leung, T. A. O’Brien, F. M. Ralph, J. Rutz, P. A. Ullrich, and M. Wehner

Subjects
Geophysics
Abstract

Atmospheric rivers, or long but narrow regions of enhanced water vapor transport, are an important component of the hydrologic cycle as they are responsible for much of the poleward transport of water vapor and result in precipitation, sometimes extreme in intensity. Despite their importance, much uncertainty remains in the detection of atmospheric rivers in large datasets such as reanalyses and century scale climate simulations. To understand this uncertainty, the Atmospheric River Tracking Method Intercomparison Project (ARTMIP) developed tiered experiments, including the Tier 2 Reanalysis Intercomparison that is presented here. Eleven detection algorithms submitted hourly tags--binary fields indicating the presence or absence of atmospheric rivers--of detected atmospheric rivers in the Modern Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2) and European Centre for Medium-Range Weather Forecasts' Reanalysis Version 5 (ERA5) as well as six-hourly tags in the Japanese 55-year Reanalysis (JRA-55). Due to a higher climatological mean for integrated water vapor transport in MERRA-2, atmospheric rivers were detected more frequently relative to the other two reanalyses, particularly in algorithms that use a fixed threshold for water vapor transport. The finer horizontal resolution of ERA5 resulted in narrower atmospheric rivers and an ability to detect atmospheric rivers along resolved coastlines. The fraction of hemispheric area covered by ARs varies throughout the year in all three reanalyses, with different atmospheric river detection tools having different seasonal cycles.

Published
2022
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25. Fatigue and fracture research in composite materials

Author

T. Kevin O'Brien

Subjects
Composite Materials
Abstract

The fatigue, fracture, and impact behavior of composite materials are investigated. Bolted and bonded joints are included. The solutions developed are generic in scope and are useful for a wide variety of structural applications. The analytical tools developed are used to demonstrate the damage tolerance, impact resistance, and useful fatigue life of structural composite components. Standard tests for screening improvements in materials and constituents are developed.

Published
1982

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