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arXiv 2022年

作者： Rigby, Jane Perrin, Marshall McElwain, Michael Kimble, Randy Friedman, Scott Lallo, Matt Doyon, René Feinberg, Lee Ferruit, Pierre Glasse, Alistair Rieke, Marcia Rieke, George Wright, Gillian Willott, Chris Colon, Knicole Milam, Stefanie Neff, Susan Stark, Christopher Valenti, Jeff Abell, Jim Abney, Faith Abul-Huda, Yasin Acton, D. Scott Adams, Evan Adler, David Aguilar, Jonathan Ahmed, Nasif Albert, Loïc Alberts, Stacey Aldridge, David Allen, Marsha Altenburg, Martin Álvarez-Márquez, Javier de Oliveira, Catarina Alves Andersen, Greg Anderson, Harry Anderson, Sara Argyriou, Ioannis Armstrong, Amber Arribas, Santiago Artigau, Etienne Arvai, Amanda Atkinson, Charles Bacon, Gregory Bair, Thomas Banks, Kimberly Barrientes, Jaclyn Barringer, Bruce Bartosik, Peter Bast, William Baudoz, Pierre Beatty, Thomas Bechtold, Katie Beck, Tracy Bergeron, Eddie Bergkoetter, Matthew Bhatawdekar, Rachana Birkmann, Stephan Blazek, Ronald Blome, Claire Boccaletti, Anthony Böker, Torsten Boia, John Bonaventura, Nina Bond, Nicholas Bosley, Kari Boucarut, Ray Bourque, Matthew Bouwman, Jeroen Bower, Gary Bowers, Charles Boyer, Martha Bradley, Larry Brady, Greg Braun, Hannah Breda, David Bresnahan, Pamela Bright, Stacey Britt, Christopher Bromenschenkel, Asa Brooks, Brian Brooks, Keira Brown, Bob Brown, Matthew Brown, Patricia Bunker, Andy Burger, Matthew Bushouse, Howard Cale, Steven Cameron, Alex Cameron, Peter Canipe, Alicia Caplinger, James Caputo, Francis Cara, Mihai Carey, Larkin Carniani, Stefano Carrasquilla, Maria Carruthers, Margaret Case, Michael Catherine, Riggs Chance, Don Chapman, George Charlot, Stéphane Charlow, Brian Chayer, Pierre Chen, Bin Cherinka, Brian Chichester, Sarah Chilton, Zack Chonis, Taylor Clampin, Mark Clark, Charles Clark, Kerry Coe, Dan Coleman, Benee Comber, Brian Comeau, Tom Connolly, Dennis Cooper, James Cooper, Rachel Coppock, Eric Correnti, Matteo Cossou, Christophe Coulais, Alain Coyle, Laura Cracraft, Misty Curti, Mirko Cuturic, Steven Davis, Katherine Davis, Michael Dean, Bruce DeLisa, Amy deMeest NASA's Goddard Space Flight Center United States Space Telescope Science Institute United States Université de Montréal Canada European Space Agency United Kingdom UK Astronomy Technology Centre United Kingdom University of Arizona United States Canada Ball Aerospace United States Honeywell International United States Airbus Defence and Space GmbH Germany Spain Katholieke Universiteit Leuven Belgium Northrop Grumman Space Systems United States Observatoire de Paris France Niels Bohr Institute Denmark Max-Planck-Institut für Astronomie Germany Jet Propulsion Laboratory California Institute of Technology United States University of Oxford United Kingdom Scuola Normale Superiore di Pisa Italy Institut d'Astrophysique de Paris France Commissariat à l'énergie Atomique et aux énergies Alternatives France University of Cambridge United Kingdom Canadian Space Agency Canada Center for Astrophysics | Harvard & Smithsonian United States Rutherford Appleton Laboratory United Kingdom Lockheed Martin Advanced Technology Center United States ATG Europe for the European Space Agency Netherlands Eidgenössische Technische Hochschule Switzerland NASA's Ames Research Center United States Association of Universities for Research in Astronomy United States National Aeronautics and Space Administration United States University of California Santa Cruz United States University of Copenhagen Denmark Dublin Institute for Advanced Studies Ireland AURA for the European Space Agency United States Telespazio UK for the European Space Agency United Kingdom Aurora Technology for the European Space Agency Netherlands Quantum Circuits United States University of Groningen Netherlands ATA Aerospace United States Heliospace United States NASA's Johnson Space Center United States John Hopkins University United States Princeton University United States University of Leicester United Kingdom

This paper characterizes the actual science performance of the James Webb Space Telescope (JWST), as determined from the six month commissioning period. We summarize the performance of the spacecraft, telescope, science instruments, and ground system, with an emphasis on differences from pre-launch expectations. Commissioning has made clear that JWST is fully capable of achieving the discoveries for which it was built. Moreover, almost across the board, the science performance of JWST is better than expected;in most cases, JWST will go deeper faster than expected. The telescope and instrument suite have demonstrated the sensitivity, stability, image quality, and spectral range that are necessary to transform our understanding of the cosmos through observations spanning from near-earth asteroids to the most distant galaxies. © 2022, CC BY.

关键词： Asteroids

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Overview of composite airframe life extension program project 2: Tools for assessing the durability and damage tolerance of fastened composite joints

Overview of composite airframe life extension program projec...

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AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 2018

作者： Bartley-Cho, Jonathan D. Palm, Tod E. Ranatunga, Vipul Northrop Grumman Corporation Advanced Structures Development Group One Space Park Redondo BeachCA90278 United States Structures Technology Branch Air Force Research Laboratory Wright-Patterson AFB 2790 D Street OH45433 United States

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Possible unconventional surface superconductivity in the half-Heusler compound YPtBi

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Physical Review B 2025年第24期111卷 245417-245417页

作者： Eylon Persky Alan Fang Xinyang Zhang Carolina Adamo Phillip Wu Eli Levenson-Falk Chandra Shekhar Claudia Felser Binghai Yan Aharon Kapitulnik Geballe Laboratory for Advanced Materials Stanford University Stanford California 94305 USA Stanford Institute for Materials and Energy Sciences SLAC National Accelerator Laboratory 2575 Sand Hill Road Menlo Park California 94025 USA Department of Applied Physics Stanford University Stanford California 94305 USA Present address: Northrop Grumman Corporation Redondo Beach CA 90278 USA. Present address: Center of Science Education National Chung-Hsing University Department of Chemistry Taichung City 402 Taiwan ROC. Present address: Center for Quantum Information Science and Technology University of Southern California Los Angeles California 90089 USA. Max Planck Institute for Chemical Physics of Solids 01187 Dresden Germany Department of Condensed Matter Physics Weizmann Institute of Science Rehovot 7610001 Israel Department of Physics Stanford University Stanford California 94305 USA

We report an extensive study of the noncentrosymmetric half-Heusler superconductor YPtBi, revealing an unusual relation between bulk superconductivity and the possible appearance of surface superconductivity on the (111) oriented surface, at temperatures up to three times the bulk transition temperature. Transport measurements confirmed the low carrier density of the material and its bulk superconducting transition, which was also observed in ac susceptibility through mutual inductance (MI) measurements. However, a weak signature of superconductivity in the MI measurements appeared much above the bulk transition temperature, which was further observed in scanning tunneling spectroscopy, pointing to a possible surface superconducting state. Polar Kerr effect measurements suggest that while the bulk superconductor may exhibit an unusual nodal superconducting state, only the surface state breaks time reversal symmetry. Complementary tunneling measurements on LuPtBi are used to establish the observations on YPtBi, while density-functional theory calculations may shed light on the origin of this unusual surface state.

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The James Webb Space Telescope Mission: Optical Telescope Element Design, development, and Performance

arXiv

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arXiv 2023年

作者： McElwain, Michael W. Feinberg, Lee D. Perrin, Marshall D. Clampin, Mark Mountain, C. Matt Lallo, Matthew D. Lajoie, Charles-Philippe Kimble, Randy A. Bowers, Charles W. Stark, Christopher C. Acton, D. Scott Aiello, Ken Atkinson, Charles Barinek, Beth Barto, Allison Basinger, Scott Beck, Tracy Bergkoetter, Matthew D. Bluth, Marcel Boucarut, Rene A. Brady, Gregory R. Brooks, Keira J. Brown, Bob Byard, John Carey, Larkin Carrasquilla, Maria Celeste, Sid Chae, Dan Chaney, David Chayer, Pierre Chonis, Taylor Cohen, Lester Cole, Helen J. Comeau, Thomas M. Coon, Matthew Coppock, Eric Coyle, Laura Davis, Rick Dean, Bruce H. Dziak, Kenneth J. Eisenhower, Michael Flagey, Nicolas Franck, Randy Gallagher, Benjamin Gilman, Larry Glassman, Tiffany Golnik, Gary Green, Joseph J. Grieco, John Haase, Shari Hadjimichael, Theodore J. Hagopian, John G. Hahn, Walter G. Hartig, George F. Havey, Keith A. Hayden, William L. Hellekson, Robert Hicks, Brian Holfeltz, Sherie T. Howard, Joseph M. Huguet, Jesse A. Jahne, Brian Johnson, Leslie A. Johnston, John D. Jurling, Alden S. Kegley, Jeffrey R. Kennard, Scott Keski-Kuha, Ritva A. Knight, J. Scott Kulp, Bernard A. Levi, Joshua S. Levine, Marie B. Lightsey, Paul Luetgens, Robert A. Mather, John C. Matthews, Gary W. McKay, Andrew G. Mehalick, Kimberly I. Meléndez, Marcio Messer, Ted Mosier, Gary E. Murphy, Jess Nelan, Edmund P. Niedner, Malcolm B. Noël, Darin M. Ohara, Catherine M. Ohl, Raymond G. Olczak, Eugene Osborne, Shannon B. Park, Sang Patton, Kevin Perrygo, Charles Pueyo, Laurent Quesnel, Lisbeth Ranck, Dale Redding, David C. Regan, Michael W. Reynolds, Paul Rifelli, Rich Rigby, Jane R. Sabatke, Derek Saif, Babak N. Scorse, Thomas R. Seo, Byoung-Joon Shi, Fang Sigrist, Norbert Smith, Koby Smith, J. Scott Smith, Erin C. Sohn, Sangmo Tony Spina, John Stahl, H. Philip Telfer, Randal Terlecki, Todd Texter, Scott C. Van Buren, David Van Campen, Julie M. Vila, Begoña Voyton, Mark F. Waldman, Mark Walker, Chanda B. Weiser, Nick Wells, Conrad West, Garrett Whitman, Tony L. Wick, Eric Wolf, E NASA Goddard Space Flight Center 8800 Greenbelt Road GreenbeltMD20771 United States Space Telescope Science Institute 3700 San Martin Drive BaltimoreMD21218 United States NASA Headquarters 300 E Street SW WashingtonDC20546 United States Association of Universities for Research in Astronomy 1331 Pennsylvania Avenue NW Suite 1475 WashingtonDC20004 United States Ball Aerospace and Technologies Corporation 1600 Commerce Street BoulderCO80301 United States Northrop Grumman Space Systems 1 Space Park Boulevard Redondo BeachCA90278 United States Jet Propulsion Laboratory California Institute of Technology 4800 Oak Grove Dr PasadenaCA91109 United States 3700 Bay Area Blvd #600 HoustonTX77058 United States Laboratory for Atmospheric and Space Physics 1234 Innovation Dr BoulderCO80303 United States NASA Johnson Space Center 2101 E NASA Parkway HoustonTX77058 United States Smithsonian Astrophysical Observatory CambridgeMA United States NASA Marshall Space Flight Center 4600 Rideout Road HuntsvilleAL35812 United States L3Harris Corporation Space and Intelligence Systems 400 Initiative Drive P.O. Box 60488 RochesterNY14606 United States Thirty Meter Telescope 100 West Walnut Street Suite 300 PasadenaCA91124 United States Lambda Consulting LLC Advanced NanoPhotonics 4437 Windsor Farm Road HarwoodMD20776 United States Aerodyne Industries 8910 Astronaut Blvd #208 Cape CanaveralFL32920 United States Genesis Engineering Solutions Inc. 4501 Boston Way LanhamMD20706 United States SAIC 12010 Sunset Hills Road RestonVA20190 United States KBR 6200 Guardian Gateway Suite 105 AberdeenMD21005 United States ATA Aerospace 7474 Greenway Center Drive GreenbeltMD20770 United States

The James Webb Space Telescope (JWST) is a large, infrared space telescope that has recently started its science program which will enable breakthroughs in astrophysics and planetary science. Notably, JWST will provide the very first observations of the earliest luminous objects in the Universe and start a new era of exoplanet atmospheric characterization. This transformative science is enabled by a 6.6 m telescope that is passively cooled with a 5-layer sunshield. The primary mirror is comprised of 18 controllable, low areal density hexagonal segments, that were aligned and phased relative to each other in orbit using innovative image-based wavefront sensing and control algorithms. This revolutionary telescope took more than two decades to develop with a widely distributed team across engineering disciplines. We present an overview of the telescope requirements, architecture, development, superb on-orbit performance, and lessons learned. JWST successfully demonstrates a segmented aperture space telescope and establishes a path to building even larger space telescopes. © 2023, CC BY.

关键词： Space telescopes

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Overview of database generation for development of bolted composite joint fatigue methods 32

Overview of database generation for development of bolted co...

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32nd Technical Conference of the American Society for Composites 2017

作者： Bartley-Cho, Jonathan Ranatunga, Vipul Smyers, Brian Knoth, Philip Northrop Grumman Corporation Advanced Structures Development Group One Space Park Redondo BeachCA90278 United States AFRL Structures Technology Branch WPAFB OH45433 United States

ISBN: (纸本)9781510853065

In anticipation of service life extension for airframes in the United States Air Force (USAF) with composite materials, Air Force Research Laboratory (AFRL) is currently developing various tools for durability and damage tolerance (DADT) assessment of bolted composites joints. Under AFRL's Composite Airframe Life Extension (CALL) Project 2 program, parametric and progressive damage analysis (PDA) tools were developed for such purpose. As part of the tools development under Project 2, over 150 single shear bearing (SSB), open- and filled-hole tension and compression (OHT/FHT and OHC/FHC) and tension bearing-bypass (BB) specimens were tested in static, constant amplitude (CA) fatigue, and CA block fatigue loading to establish a database for the semi-empirical parametric model while also providing opportunities for iterative maturation of the PDA tools through many prediction/calibration cycles. Stress ratios, R, in the range of-1.0 to 0.1 were used in CA and CA block fatigue tests as one of the goals for the program was to develop tools capable of variable fatigue stress and amplitude. All specimens were fabricated from toughened 350°F-cure carbon/epoxy unidirectional material and consisted of three thidmesses-0.143", 0.191", and 0.239"-from [44/44/12] laminate family. The fastener used was a 1/4" diameter stainless steel 100° flush head rivet pin that is commonly used in production. The tests were performed at both northrop grumman Corporation (NGC) and AFRL. These tests provided data on 1) static response, 2) hole elongation %e) vs number of cycles (N), 3) joint stiffness (k/ko) vs N, and 4) residual strength and/or S-N with respect to diameter-to-thickness ratio (D/t), R, fastener preload, and fatigue load profile (i.e., CA vs CA block spectrum). This paper will provide an overview of the various test methods, summary of key results from the trial phase of the 150+ tests, and the effects of these test results on the remainder of the program testing approach. Copyri

关键词： Airframes

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Test and analysis of a buckling-critical large-scale sandwich composite cylinder

Test and analysis of a buckling-critical large-scale sandwic...

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AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 2018

作者： Schultz, Marc R. Sleight, David W. Gardner, Nathaniel W. Rudd, Michelle T. Hilburger, Mark W. Palm, Tod E. Oldfield, Nathan J. NASA Langley Research Center Structural Mechanics and Concepts Branch 8 West Taylor St. Mail Stop 190 HamptonVA23681 United States NASA Langley Research Center Structural and Thermal Systems Branch 1 North Dryden St. MS 431 HamptonVA23681 United States Analytical Services & Materials Inc. Structural Materials and Concepts Branch 8 West Taylor St. Mail Stop 190 HamptonVA23681 United States NASA Marshall Space Flight Center Dynamics Loads & Strength Branch 4600 Rideout Rd. EV31 HuntsvilleAL35812 United States NASA Langley Research Center Structural Mechanics and Concepts Branch 8 West Taylor St. Mail Stop 190 HamptonVA23681 United States Northrop Grumman Corporation Airframe Technology Development One Space Park Redondo BeachCA90278 United States Northrop Grumman Corporation Responsive Space Access 301 Voyager Way M/S UAL312-128D HuntsvilleAL35806 United States

ISBN: (数字)9781624105326

ISBN: (纸本)9781624105326

Structural stability is an important design consideration for launch-vehicle shell structures and it is well known that the buckling response of such shell structures can be very sensitive to small geometric imperfections. As part of an effort to develop new buckling design guidelines for sandwich composite cylindrical shells, an 8-ft-diameter honeycomb-core sandwich composite cylinder was tested under pure axial compression to failure. The results from this test are compared with finite-element-analysis predictions and overall agreement was very good. In particular, the predicted buckling load was within 1% of the test and the character of the response matched well. However, it was found that the agreement could be improved by including composite material nonlinearity in the analysis, and that the predicted buckling initiation site was sensitive to the addition of small bending loads to the primary axial load in analyses. © 2018, (publisher Name). All rights reserved.

关键词： Buckling

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The James Webb Space Telescope Mission

arXiv

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arXiv 2023年

作者： Gardner, Jonathan P. Mather, John C. Abbott, Randy Abell, James S. Abernathy, Mark Abney, Faith E. Abraham, John G. Abraham, Roberto Abul-Huda, Yasin M. Acton, Scott Adams, Cynthia K. Adams, Evan Adler, David S. Adriaensen, Maarten Aguilar, Jonathan Albert Ahmed, Mansoor Ahmed, Nasif S. Ahmed, Tanjira Albat, Rüdeger Albert, Loïc Alberts, Stacey Aldridge, David Allen, Mary Marsha Allen, Shaune S. Altenburg, Martin Altunc, Serhat Alvarez, Jose Lorenzo Álvarez-Márquez, Javier de Oliveira, Catarina Alves Ambrose, Leslie L. Anandakrishnan, Satya M. Andersen, Gregory C. Anderson, Harry James Anderson, Jay Anderson, Kristen Anderson, Sara M. Aprea, Julio Archer, Benita J. Arenberg, Jonathan W. Argyriou, Ioannis Arribas, Santiago Artigau, Étienne Arvai, Amanda Rose Atcheson, Paul Atkinson, Charles B. Averbukh, Jesse Aymergen, Cagatay Bacinski, John J. Baggett, Wayne E. Bagnasco, Giorgio Baker, Lynn L. Balzano, Vicki Ann Banks, Kimberly A. Baran, David A. Barker, Elizabeth A. Barrett, Larry K. Barringer, Bruce O. Barto, Allison Bast, William Baudoz, Pierre Baum, Stefi Beatty, Thomas G. Beaulieu, Mathilde Bechtold, Kathryn Beck, Tracy Beddard, Megan M. Beichman, Charles Bellagama, Larry Bely, Pierre Berger, Timothy W. Bergeron, Louis E. Darveau-Bernier, Antoine Bertch, Maria D. Beskow, Charlotte Betz, Laura E. Biagetti, Carl P. Birkmann, Stephan Bjorklund, Kurt F. Blackwood, James D. Blazek, Ronald Paul Blossfeld, Stephen Bluth, Marcel Boccaletti, Anthony Boegner, Martin E. Bohlin, Ralph C. Boia, John Joseph Böker, Torsten Bonaventura, N. Bond, Nicholas A. Bosley, Kari Ann Boucarut, Rene A. Bouchet, Patrice Bouwman, Jeroen Bower, Gary Bowers, Ariel S. Bowers, Charles W. Boyce, Leslye A. Boyer, Christine T. Boyer, Martha L. Boyer, Michael Boyer, Robert Bradley, Larry D. Brady, Gregory R. Brandl, Bernhard R. Brannen, Judith L. Breda, David Bremmer, Harold G. Brennan, David Bresnahan, Pamela A. Bright, Stacey N. Broiles, Brian J. Bromenschenkel, Asa Brooks, Brian H. Brooks, Keira J. Brown, Bob Brown, Bruce Brown, Thomas M. Br NASA Goddard Space Flight Center 8800 Greenbelt Rd GreenbeltMD20771 United States Ball Aerospace & Technologies Corp. 1600 Commerce Street BoulderCO80301 United States Space Telescope Science Institute 3700 San Martin Drive BaltimoreMD21218 United States Department of Astronomy & Astrophysics University of Toronto 50 St. George Street TorontoONM5S 3H4 Canada Dunlap Institute for Astronomy and Astrophysics University of Toronto 50 St George Street TorontoONM5S 3H4 Canada European Space Agency HQ Daumesnil 52 rue Jacques Hillairet Paris75012 France Université de Montréal Département de Physique C.P. 6128 Succ. Centre-ville MontréalQCH3C 3J7 Canada Steward Observatory University of Arizona 933 N. Cherry Ave TucsonAZ85721 United States Honeywell Aerospace #100 303 Terry Fox Drive OttawaONK2K 3J1 Canada Airbus Defence and Space GmbH Ottobrunn Germany European Space Agency European Research & Technology Centre Keplerlaan 1 Postbus 299 Noordwijk2200 AG Netherlands Carretera de Ajalvir Torrejón de Ardoz MadridE-28850 Spain European Space Agency European Space Astronomy Centre Camino bajo del Castillo s/n Urbanización Villafranca del Castillo Villanueva de la Cañada Madrid28692 Spain Northrop Grumman One Space Park Redondo BeachCA90278 United States Instituut voor Sterrenkunde KU Leuven Celestijnenlaan 200D Bus-2410 Leuven3000 Belgium LESIA Observatoire de Paris Université PSL CNRS Sorbonne Université Université de Paris 5 place Jules Janssen Meudon92195 France Faculty of Science University of Manitoba 230 Machray Hall 186 Dysart Road WinnipegMBR3T 2N2 Canada Department of Astronomy University of Wisconsin Madison MadisonWI53706 United States Université Côte d’Azur Observatoire de la Côte d’Azur CNRS Laboratoire Lagrange NiceF-06108 France NASA Exoplanet Science Institute IPAC Jet Propulsion Laboratory California Institute of Technology 1200 E California Blvd PasadenaCA91125 United States European Space

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least 4m. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the 6.5m James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit. © 2023, CC BY.

关键词： Space telescopes

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Energetic electron precipitation driven by electromagnetic ion cyclotron waves from ELFIN’s low altitude perspective

arXiv

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arXiv 2022年

作者： Angelopoulos, V. Zhang, X.-J. Artemyev, A.V. Mourenas, D. Tsai, E. Wilkins, C. Runov, A. Liu, J. Turner, D.L. Li, W. Khurana, K. Wirz, R.E. Sergeev, V.A. Meng, X. Wu, J. Hartinger, M.D. Raita, T. Shen, Y. An, X. Shi, X. Bashir, M.F. Shen, X. Gan, L. Qin, M. Capannolo, L. Ma, Q. Russell, C.L. Masongsong, E.V. Caron, R. He, I. Iglesias, L. Jha, S. King, J. Kumar, S. Le, K. Mao, J. McDermott, A. Nguyen, K. Norris, A. Palla, A. Roosnovo Tam, J. Xie, E. Yap, R.C. Ye, S. Young, C. Adair, L.A. Shaffer, C. Chung, M. Cruce, P. Lawson, M. Leneman, D. Allen, M. Anderson, M. Arreola-Zamora, M. Artinger, J. Asher, J. Branchevsky, D. Cliffe, M. Colton, K. Costello, C. Depe, D. Domae, B.W. Eldin, S. Fitzgibbon, L. Flemming, A. Frederick, D.M. Gilbert, A. Hesford, B. Krieger, R. Lian, K. McKinney, E. Miller, J.P. Pedersen, C. Qu, Z. Rozario, R. Rubly, M. Seaton, R. Subramanian, A. Sundin, S.R. Tan, A. Thomlinson, D. Turner, W. Wing, G. Wong, C. Zarifian, A. Earth Planetary and Space Sciences Department Institute of Geophysics and Planetary Physics University of California Los Angeles Los AngelesCA90095 United States University of Texas at Dallas RichardsonTX75080 United States CEA DAM DIF Arpajon France Atmospheric and Oceanic Sciences Departments University of California Los AngelesCA United States Johns Hopkins University Applied Physics Laboratory LaurelMD United States Department of Astronomy Center for Space Physics Boston University BostonMA United States Mechanical and Aerospace Engineering Department Henry Samueli School of Engineering University of California Los AngelesCA90095 United States School of Mechanical Industrial Manufacturing Engineering Oregon State University CorvallisOR97331 United States University of St. Petersburg St. Petersburg Russia Jet Propulsion Laboratory California Institute of Technology PasadenaCA91109 United States Space Science Institute BoulderCO80301 United States Sodankylä Geophysical Observatory University of Oulu Sodankylä Finland Materials Science and Engineering Department Henry Samueli School of Engineering University of California Los AngelesCA90095 United States Deloitte Consulting New YorkNY10112 United States Computer Science Department Henry Samueli School of Engineering University of California Los AngelesCA90095 United States Microsoft RedmondWA98052 United States Physics and Astronomy Department University of California Los AngelesCA90095 United States Department of Astronomy and Astrophysics The University of Chicago ChicagoIL60637 United States Raybeam Inc. Mountain ViewCA94041 United States SpaceX HawthorneCA90250 United States Reliable Robotics Corporation Mountain ViewCA94043 United States Los Alamos National Laboratory Los AlamosNM87545 United States Mathematics Department University of California Los AngelesCA90095 United States Planet Labs PBC San FranciscoCA94107 United States KSAT Inc. De

We review comprehensive observations of electromagnetic ion cyclotron (EMIC) wave-driven energetic electron precipitation using data from the energetic electron detector on the Electron Losses and Fields InvestigatioN (ELFIN) mission, two polar-orbiting low-altitude spinning CubeSats, measuring 50-5000 keV electrons with good pitch-angle and energy resolution. EMIC wave-driven precipitation exhibits a distinct signature in energy-spectrograms of the precipitating-to-trapped flux ratio: peaks at >0.5 MeV which are abrupt (bursty) (lasting ∼17s, or ∆L ∼ 0.56) with significant substructure (occasionally down to sub-second timescale). We attribute the bursty nature of the precipitation to the spatial extent and structuredness of the wave field at the equator. Multiple ELFIN passes over the same MLT sector allow us to study the spatial and temporal evolution of the EMIC wave - electron interaction region. Case studies employing conjugate ground-based or equatorial observations of the EMIC waves reveal that the energy of moderate and strong precipitation at ELFIN approximately agrees with theoretical expectations for cyclotron resonant interactions in a cold plasma. Using 2 years of ELFIN data uniformly distributed in local time, we assemble a statistical database of ∼50 events of strong EMIC wave-driven precipitation. Most reside at L ∼ 5 − 7 at dusk, while a smaller subset exists at L ∼ 8 − 12 at post-midnight. The energies of the peak-precipitation ratio and of the half-peak precipitation ratio (our proxy for the minimum resonance energy) exhibit an L-shell dependence in good agreement with theoretical estimates based on prior statistical observations of EMIC wave power spectra. The precipitation ratio’s spectral shape for the most intense events has an exponential falloff away from the peak (i.e., on either side of ∼ 1.45 MeV). It too agrees well with quasi-linear diffusion theory based on prior statistics of wave spectra. It should be noted though that this diffusive

关键词： Radiation belts

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Validation process of the physics-based modeling of navigation sensors for sea-based aviation automated landing

Validation process of the physics-based modeling of navigati...

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AIAA Modeling and Simulation Technologies Conference, 2016

作者： Good, Nathan Aboutalib, Omar Thai, Bea Yamaoka, Neil Kim, Charles Wilkinson, Colin H. Findlay, David B. Advanced Research and Technology Department United States Advanced Technology Center United States Applied Aerodynamics and Store Separation Branch 48110 Shaw Road Bldg. 2187 Aeromechanics Division 48110 Shaw Road Bldg. 2187 Northrop Grumman Aerospace Systems 1 Space Park Redondo BeachCA90278 United States Northrop Grumman Electronic Systems 600 Hicks Road Rolling MeadowsIL60008 United States Patuxent RiverMD20670 United States

ISBN: (数字)9781624103872

ISBN: (纸本)9781624103872

In this paper, a rigorous and reliable process is presented for the validation of a physics-based multi-sensor simulation required for the development of the Sea-based Automated Launch and Recovery System (SALRS). Recent advances in physics-based passive and active sensor modeling have given rise to the concept of using simulations to perform cost effective trade analyses to determine the optimal set of sensors required to meet the SALRS mission requirements. Physics-based multi-sensor simulation is required to test key SALRS functionalities including the detection and identification of the designated landing ship, detection and tracking of the ship deck, detection of ship deck features for navigation aid, estimating ship deck motion for soft landing, and timely detection of hazards for safe landing and recovery. Sensor model simulation presents two basic challenges: model verification and model validation. Model verification is the process of determining that the model is implemented correctly, while model validation is the process of determining the degree to which the output of the sensor model is an accurate representation of real sensor output from the perspective of its intended use. Although verification is a challenging problem, validation is general-ly a more difficult process. The validation process presented in this paper is based on decomposing the physics-based model into its basic components and performing piece-wise component validation, as well as a total model validation to achieve reliable validation results. This rigorous validation process builds trust in the sensor models and their ability to accurately simulate the environment, enabling the exploitation of the synergy among multiple sensors in degraded conditions. This formal validation process enables the Navy to receive systematic updates to the sensor simulation input files due to the introduction of any new sensor hardware, new ship deck materials, or newly collected at-sea degraded conditi

关键词： Landing

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A method for predicting fastener hole elongationin composite joints due to cyclic loading 57

A method for predicting fastener hole elongationin composite...

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57th AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 2016

作者： Bartley-Cho, Jonathan D. Wang, Donny P. Sheppard, William R. Palm, Tod E. Holzwarth, Richard C. Wilkinson, Capt Michael P. Advanced Structures Development Group Northrop Grumman Aerospace Systems One Space Park Redondo BeachCA90278 United States Air Force Research Laboratory Structures Technology Branch Wright-Patterson AFB 2790 D Street OH45433 United States United States Air Force Academy Department of Aeronautics 2410 Faculty Drive Colorado SpringsCO80840 United States Advanced Materials and Processes Group One Hornet Way El SegundoCA90245 United States

ISBN: (数字)9781624103926

ISBN: (纸本)9781624103926

Based on the current operational and sustainment trends in the United States Air Force (USAF), modern airframes with high composite content in primary structures will likely undergo a service life extension program (SLEP) in the future. However, unlike for metallic airframes, the USAF currently has no experience in SLEP of composites, with few enabling technical tools. One such tool is a lifing method for assessing fatigue life used and remaining for bolted joints. Virtually all of the composite airframes currently in service in USAF are assembled with fasteners. Structural integrity requirements dictate that these joints remain functional—i.e., capable of transferring load–over the design service life. One approach to meeting this requirement is to limit the hole elongation to a maximum value—e.g., 4%--relative to the nominal hole diameter. The certification process for such joints must demonstrate that detrimental hole wear does not occur during the design service life. However, if the aircraft mission changes or service life must be increased or both, the USAF must assure that these joints will remain structurally functional. In order to recertify the composite joints for use beyond the original design service life without resorting to extensive testing, an analytical method for predicting fastener hole elongation is necessary. This paper details the development and initial verification of an engineering approach for predicting bolt hole elongation that was performed under "Assess technology for Performing a Structural Life Extension Program for advanced Composite Airframe Structures" program funded by the Air Force Research Laboratory (AFRL). A total of 63 bearing specimens were excised from several 36-ply, 0.187 inch thick, [44/44/11] laminates made from IM7/977-3 unidirectional tape. These specimens were tested in a double lap shear configuration with ¼-inch high-strength (220 ksi Ftu) stainless steel bolts. Twenty two (22) constant amplitude (CA) bearing fati

关键词： Airframes

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