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  • STRUCTURAL MECHANICS  (5)
  • Animals  (4)
  • MECHANICAL ENGINEERING
  • 2005-2009
  • 1990-1994  (11)
  • 1980-1984
  • 1993  (11)
  • 1
    Publication Date: 2013-08-31
    Description: Composite structures have the potential to be cost-effective, structurally efficient primary aircraft structures. The Advanced Composites Technology (ACT) Program has the goal to develop the technology to exploit this potential for heavily loaded aircraft structures. As part of the ACT Program, Lockheed Aeronautical Systems Company completed the design and fabrication of the Technology Integration Box Beam (TIBB). The TIBB is an advanced composite prototype structure for the center wing section of the C-130 aircraft. Lockheed subjected the TIBB to downbending, upbending, torsion and combined upbending and torsion load conditions to verify the design. The TIBB failed at 83 percent of design ultimate load for the combined upbending and torsion load condition. The objective of this paper is to describe the mechanisms that led to the failure of the TIBB. The results of a comprehensive analytical and experimental study are presented. Analytical results include strain and deflection results from both a global analysis of the TIBB and a local analysis of the failure region. These analytical results are validated by experimental results from the TIBB tests. The analytical and experimental results from the TIBB tests are used to determine a sequence of events that resulted in failure of the TIBB. A potential cause of failure is high stresses in a stiffener runout region. Analytical and experimental results are also presented for a stiffener runout specimen that was used to simulate the TIBB failure mechanisms.
    Keywords: STRUCTURAL MECHANICS
    Type: Third NASA Advanced Composites Technology Conference, Volume 1, Part 2; p 951-965
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  • 2
    Publication Date: 1993-05-14
    Description: The CD4 antigen is a membrane glycoprotein of T lymphocytes that interacts with major histocompatibility complex class II antigens and is also a receptor for the human immunodeficiency virus. the extracellular portion of CD4 is predicted to fold into four immunoglobulin-like domains. The crystal structure of the third and fourth domains of rat CD4 was solved at 2.8 angstrom resolution and shows that both domains have immunoglobulin folds. Domain 3, however, lacks the disulfide between the beta sheets; this results in an expansion of the domain. There is a difference of 30 degrees in the orientation between domains 3 and 4 when compared with domains 1 and 2. The two CD4 fragment structures provide a basis from which models of the overall receptor can be proposed. These models suggest an extended structure comprising two rigid portions joined by a short and possibly flexible linker region.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Brady, R L -- Dodson, E J -- Dodson, G G -- Lange, G -- Davis, S J -- Williams, A F -- Barclay, A N -- New York, N.Y. -- Science. 1993 May 14;260(5110):979-83.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, University of York, United Kingdom.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8493535" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Antigens, CD4/*chemistry ; Crystallization ; Humans ; Models, Molecular ; Molecular Sequence Data ; Protein Conformation ; Protein Folding ; Protein Structure, Secondary ; Rats ; Sequence Alignment ; X-Ray Diffraction
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 1993-03-19
    Description: The alpha component of the receptor for ciliary neurotrophic factor (CNTF) differs from other known growth factor receptors in that it is anchored to cell membranes by a glycosylphosphatidylinositol linkage. One possible function of this type of linkage is to allow for the regulated release of this receptor component. Cell lines not normally responsive to CNTF responded to treatment with a combination of CNTF and a soluble form of the CNTF alpha receptor component. These findings not only demonstrate that the CNTF receptor alpha chain is a required component of the functional CNTF receptor complex but also reveal that it can function in soluble form as part of a heterodimeric ligand. Potential physiological roles for the soluble CNTF receptor are suggested by its presence in cerebrospinal fluid and by its release from skeletal muscle in response to peripheral nerve injury.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Davis, S -- Aldrich, T H -- Ip, N Y -- Stahl, N -- Scherer, S -- Farruggella, T -- DiStefano, P S -- Curtis, R -- Panayotatos, N -- Gascan, H -- New York, N.Y. -- Science. 1993 Mar 19;259(5102):1736-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Regeneron Pharmaceuticals, Inc., Tarrytown, NY 10591.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7681218" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cell Differentiation/drug effects ; Cell Division/drug effects ; Cell Membrane/metabolism ; Ciliary Neurotrophic Factor ; Cloning, Molecular ; Gene Expression ; Glycosylphosphatidylinositols/metabolism ; Growth Inhibitors/pharmacology ; Hematopoietic Stem Cells/cytology/drug effects ; Humans ; Interleukin-6/pharmacology ; Leukemia Inhibitory Factor ; Lymphokines/pharmacology ; Mice ; Muscle Denervation ; Muscles/innervation/metabolism ; Nerve Tissue Proteins/*pharmacology ; Phosphatidylinositol Diacylglycerol-Lyase ; Phosphoric Diester Hydrolases/metabolism ; Phosphotyrosine ; RNA, Messenger/genetics ; Rats ; Receptor, Ciliary Neurotrophic Factor ; Receptors, Cell Surface/chemistry/*physiology ; Signal Transduction/physiology ; Tumor Cells, Cultured ; Tyrosine/analogs & derivatives/metabolism
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 4
    Publication Date: 1993-06-18
    Description: The ciliary neurotrophic factor (CNTF) receptor complex is shown here to include the CNTF binding protein (CNTFR alpha) as well as the components of the leukemia inhibitory factor (LIF) receptor, LIFR beta (the LIF binding protein) and gp130 [the signal transducer of interleukin-6 (IL-6)]. Thus, the conversion of a bipartite LIF receptor into a tripartite CNTF receptor apparently occurs by the addition of the specificity-conferring element CNTFR alpha. Both CNTF and LIF trigger the association of initially separate receptor components, which in turn results in tyrosine phosphorylation of receptor subunits. Unlike the IL-6 receptor complex in which homodimerization of gp130 appears to be critical for signal initiation, signaling by the CNTF and LIF receptor complexes depends on the heterodimerization of gp130 with LIFR beta. Ligand-induced dimerization of signal-transducing receptor components, also seen with receptor tyrosine kinases, may provide a general mechanism for the transmission of a signal across the cell membrane.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Davis, S -- Aldrich, T H -- Stahl, N -- Pan, L -- Taga, T -- Kishimoto, T -- Ip, N Y -- Yancopoulos, G D -- New York, N.Y. -- Science. 1993 Jun 18;260(5115):1805-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Regeneron Pharmaceuticals, Inc., Tarrytown, NY 10591.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8390097" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Antigens, CD ; Cell Line ; Cytokine Receptor gp130 ; Growth Inhibitors/pharmacology ; Interleukin-6/pharmacology ; Leukemia Inhibitory Factor ; Lymphokines/pharmacology ; Macromolecular Substances ; Membrane Glycoproteins/chemistry/*metabolism ; Models, Biological ; Nerve Growth Factors ; Nerve Tissue Proteins/pharmacology ; Phosphorylation ; Receptor, Ciliary Neurotrophic Factor ; Receptors, Cell Surface/chemistry/*metabolism ; *Receptors, Cytokine ; Receptors, Immunologic/chemistry/*metabolism ; Receptors, Interleukin-6 ; Receptors, OSM-LIF ; *Signal Transduction ; Tumor Cells, Cultured ; Tyrosine/metabolism
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 5
    Publication Date: 1993-03-19
    Description: Tyrosine phosphorylation of proteins is required for signal transduction in cells and for growth regulation. A mitogen-induced gene (PAC-1) has been cloned from human T cells and encodes a 32-kilodalton protein that contains a sequence that defines the enzymatic site of known protein phosphotyrosine phosphatases (PTPases). Other than this sequence, PAC-1 is different from several other known related PTPases exemplified by PTP-1b. PAC-1 is similar to a phosphatase induced by mitogens or heat shock in fibroblasts, a yeast gene, and a vaccinia virus-encoded serine-tyrosine phosphatase (VH1). PAC-1 was predominantly expressed in hematopoietic tissues and localized to the nucleus in transfected COS-7 cells and in mitogen-stimulated T cells.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rohan, P J -- Davis, P -- Moskaluk, C A -- Kearns, M -- Krutzsch, H -- Siebenlist, U -- Kelly, K -- New York, N.Y. -- Science. 1993 Mar 19;259(5102):1763-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Pathology, National Cancer Institute, NIH, Bethesda, MD 20892.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7681221" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Blotting, Northern ; Cell Line ; Cell Nucleus/enzymology ; Conserved Sequence ; Cytoplasm/enzymology ; Dual Specificity Phosphatase 2 ; Fluorescent Antibody Technique ; Humans ; Immunosorbent Techniques ; Mice ; Mitogens/*pharmacology ; Molecular Sequence Data ; Organ Specificity ; Protein Phosphatase 2 ; Protein Tyrosine Phosphatases/chemistry/*genetics ; RNA/analysis ; Sequence Homology, Amino Acid ; Signal Transduction/physiology ; T-Lymphocytes/enzymology ; Transfection
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 6
    Publication Date: 2013-08-31
    Description: CASES (Controls, Astrophysics and Structures Experiment in Space) is a proposed space experiment to collect x-ray images of the galactic center and solar disk with unprecedented resolution. This requires precision pointing and suppression of vibrations in the long flexible structure that comprises the 32-m x-ray telescope optical bench. Two separate electro-optical sensor systems are provided for the ground test facility (GTF). The Boom Motion Tracker (BMT) measures eigenvector data for post-mission use in system identification. The Tip Displacement Sensor (TDS) measures boom tip position and is used as feedback for the closed-loop control system that stabilizes the boom. Both the BMT and the TDS have met acceptance specifications and were delivered to MSFC in February 1992. This paper describes the sensor concept, the sensor configuration as implemented in the GTF, and the results of characterization and performance testing.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Research Center, The Fifth NASA(DOD Controls-Structures Interaction Technology Conference, Part 1; p 263-275
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  • 7
    Publication Date: 2013-08-31
    Description: Objectives of the research are: (1) to develop design requirements for damped struts to stabilize control system in the high frequency cross-over and spill-over range; (2) to design, fabricate and test viscously damped strut and viscoelastically damped strut; (3) to verify accuracy of design and analysis methodology of damped struts; and (4) to design and build test apparatus, and develop data reduction algorithm to measure strut complex stiffness. In order to meet the stringent performance requirements of the SPICE experiment, the active control system is used to suppress the dynamic responses of the low order structural modes. However, the control system also inadvertently drives some of the higher order modes unstable in the cross-over and spill-over frequency range. Passive damping is a reliable and effective way to provide damping to stabilize the control system. It also improves the robustness of the control system. Damping is designed into the SPICE testbed as an integral part of the control-structure technology.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Research Center, The Fifth NASA(DOD Controls-Structures Interaction Technology Conference, Part 1; p 239-249
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  • 8
    Publication Date: 2019-06-28
    Description: Sliding tests with a pin-on-disc tribometer and both sliding and rolling tests with a modified four-ball tester at bulk temperatures of about 500 C and contact pressures of about 2.2 GPa have demonstrated up to 80% reductions of friction and wear with silicon nitride surfaces when a stream of ethylene is directed into the conjunction region. The effects are even more pronounced when the ethylene is prenucleated by a flow over a coil of nichrome wire electrically heated to about 800 C and located about 30 cm upstream of the exit nozzle. Steel and Ni-plated steel are lubricated by this method even more efficiently at lower temperatures.
    Keywords: MECHANICAL ENGINEERING
    Type: AD-A278264 , NASA-CR-189214 , NAS 1.26:189214 , EDR-16732 , AVSCOM-TR-92-C-032
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  • 9
    Publication Date: 2019-08-28
    Description: Scientific microgravity experiments conducted on platforms such as the Soviet Mir space station and the U.S. Space Shuttle indicated that the microgravity environment is contaminated with disturbances which result in the reduction of a gravity quality, from micro-g to milli-g. This paper describes the vibration isolation technology developed by the Canadian Space Agency, the 1DOF Large Motion Isolation Mount (LMIM) and the 3DOF LMIM, for the KC-135 aircraft. The results of the developmental activity are presented, and the applicability of the approach taken to the Space Shuttle, Space Station Freedom, and the Mir space station is discussed.
    Keywords: MECHANICAL ENGINEERING
    Type: AIAA PAPER 93-0574 , ; 13 p.|AIAA, Aerospace Sciences Meeting and Exhibit; Jan 11, 1993 - Jan 14, 1993; Reno, NV; United States
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  • 10
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    In:  Other Sources
    Publication Date: 2019-07-13
    Description: FEM is here used to ascertain the stability and aeroelastic response of thin, 2D panels subjected to Mach 0.8-2.5 flows. In the absence of shocks, it is found that the Euler equations used to represent the unsteady flowfield dynamics predict response behaviors resembling those obtained via potential flow methods. Where shocks do play a significant role in the overall motion of the panel, divergence and limit cycle flutter are observed. In the Mach 1.4-1.5 range, flutter involved the higher modes of the panel, tending toward possible chaotic motion.
    Keywords: STRUCTURAL MECHANICS
    Type: AIAA PAPER 93-1476 , ; 15 p.|AIAA, ASME, ASCE, AHS, and ASC, Structures, Structural Dynamics and Materials Conference, 34th and AIAA and ASME, Adaptive Structures Forum; Apr 19, 1993 - Apr 22, 1993; La Jolla, CA; United States
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