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  • Other Sources  (29)
  • Aerospace Medicine  (11)
  • SPACECRAFT PROPULSION AND POWER  (11)
  • Cybernetics, Artificial Intelligence and Robotics  (7)
  • 1
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    The presence of lysylpyridinoline in the hypertrophic cartilage of newly hatched chicks (1993)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: The presence of lysylpyridinoline (LP) as a nonreducible cross-link in appreciable quantities has primarily been limited to the mineralized tissues, bone and dentin. However, the results reported here show that LP is not only present in the hypertrophic cartilage of the tibiotarsus isolated from newly hatched broiler chicks, but it is approx. 4-fold as concentrated as hydroxylysylpyridinoline (HP). Bone and articular cartilage surrounding the hypertrophic cartilage do not contain measurable quantities of LP. Purified LP has a fluorescent scan similar to purified HP and literature values, confirming that we indeed were measuring LP. Also, the cartilage lesion produced by immature chondrocytes from birds with tibial dyschondroplasia had LP but the HP:LP ratio was 〉 1. Thus, the low HP:LP ratio could be a marker for hypertrophic cartilage in avians.
    Keywords: Aerospace Medicine
    Type: Biochimica et biophysica acta (ISSN 0006-3002); Volume 1157; 3; 229-32
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  • 2
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    Cortical bone growth and maturational changes in dwarf rats induced by recombinant human growth hormone (1996)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The growth hormone (GH)-deficient dwarf rat was used to investigate recombinant human (rh) GH-induced bone formation and to determine whether rhGH facilitates simultaneous increases in bone formation and bone maturation during rapid growth. Twenty dwarf rats, 37 days of age, were randomly assigned to dwarf plus rhGH (GH; n = 10) and dwarf plus vehicle (n = 10) groups. The GH group received 1.25 mg rhGH/kg body wt two times daily for 14 days. Biochemical, morphological, and X-ray diffraction measurements were performed on the femur middiaphysis. rhGH stimulated new bone growth in the GH group, as demonstrated by significant increases (P 〈 0.05) in longitudinal bone length (6%), middiaphyseal cross-sectional area (20%), and the amount of newly accreted bone collagen (28%) in the total pool of middiaphyseal bone collagen. Cortical bone density, mean hydroxyapatite crystal size, and the calcium and collagen contents (microgram/mm3) were significantly smaller in the GH group (P 〈 0.05). Our findings suggest that the processes regulating new collagen accretion, bone collagen maturation, and mean hydroxyapatite crystal size may be independently regulated during rapid growth.
    Keywords: Aerospace Medicine
    Type: The American journal of physiology (ISSN 0002-9513); Volume 270; 1 Pt 1; E51-9
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  • 3
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    Hindlimb unloading alters ligament healing (2003)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: We investigated the hypothesis that hindlimb unloading inhibits healing in fibrous connective tissue such as ligament. Male rats were assigned to 3- and 7-wk treatment groups with three subgroups each: sham control, ambulatory healing, and hindlimb-suspended healing. Ambulatory and suspended animals underwent surgical rupture of their medial collateral ligaments, whereas sham surgeries were performed on control animals. After 3 or 7 wk, mechanical and/or morphological properties were measured in ligament, muscle, and bone. During mechanical testing, most suspended ligaments failed in the scar region, indicating the greatest impairment was to ligament and not to bone-ligament insertion. Ligament testing revealed significant reductions in maximum force, ultimate stress, elastic modulus, and low-load properties in suspended animals. In addition, femoral mineral density, femoral strength, gastrocnemius mass, and tibialis anterior mass were significantly reduced. Microscopy revealed abnormal scar formation and cell distribution in suspended ligaments with extracellular matrix discontinuities and voids between misaligned, but well-formed, collagen fiber bundles. Hence, stress levels from ambulation appear unnecessary for formation of fiber bundles yet required for collagen to form structurally competent continuous fibers. Results support our hypothesis that hindlimb unloading impairs healing of fibrous connective tissue. In addition, this study provides compelling morphological evidence explaining the altered structure-function relationship in load-deprived healing connective tissue.
    Keywords: Aerospace Medicine
    Type: Journal of applied physiology (Bethesda, Md. : 1985) (ISSN 8750-7587); Volume 94; 1; 314-24
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  • 4
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    Effect of a growth hormone treatment on bone orthotropic elasticity in dwarf rats (1997)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: A refinement of the current ultrasonic elasticity technique was used to measure the orthotropic elastic properties of rat cortical bone as well as to quantify changes in elastic properties, density, and porosity of the dwarf rat cortex after a treatment with recombinant human growth hormone (rhGH). The ultrasonic elasticity technique was refined via optimized signal management of high-frequency wave propagation through cubic cortical specimens. Twenty dwarf rats (37 days old) were randomly assigned to two groups (10 rats each). The dwarf rat model (5-10% of normal GH) was given subcutaneous injections of either rhGH or saline over a 14-day treatment period. Density was measured using Archimedes technique. Porosity and other microstructural characteristics were also explored via scanning electron microscopy and image analysis. Statistical tests verified significant decreases in cortical orthotropic Young's (-26.7%) and shear (-16.7%) moduli and density (-2.42%) concomitant with an increase in porosity (+125%) after rhGH treatments to the dwarf model (p 〈 0.05). A change in material symmetry from orthotropy toward planar isotropy within the radial-circumferential plane after GH treatments was also noted. These results demonstrate some alteration in bone properties at this time interval. Structural implications of these changes throughout physiological loading regimens should be explored.
    Keywords: Aerospace Medicine
    Type: Annals of biomedical engineering (ISSN 0090-6964); Volume 25; 1; 77-85
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  • 5
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    MPD work at MIT (1991)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: MPD work at MIT is presented in the form of the view-graphs. The following subject areas are covered: the MIT program, its goals, achievements, and roadblocks; quasi one-dimensional modeling; two-dimensional modeling - transport effects and Hall effect; microscopic instabilities in MPD flows and modified two stream instability; electrothermal stability theory; separation of onset and anode depletion; exit plane spectroscopic measurements; phenomena of onset as performance limiter; explanations of onset; geometry effects on onset; onset at full ionization and its consequences; relationship to anode depletion; summary on self-field MPD; applied field MPD - the logical growth path; the case for AF; the challenges of AF MPD; and recommendations.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA. Lewis Research Center, Magnetoplasmadynamic Thruster Workshop; 17 p
    Format: application/pdf
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  • 6
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    Annular nozzle engine technology (1992)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: The topics covered include: (1) driver rocket subsystem; (2) annular nozzle engine technology; (3) expansion-deflection nozzle; (4) aerospike-nozzled engine background; (5) aerospike testing; (6) linear aerospike; and (7) the combined cycle engine.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA. Lewis Research Center, Rocket-Based Combined-Cycle (RBCC) Propulsion Technology Workshop. Tutorial Session; 8 p
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  • 7
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    Design of a direct nuclear propulsion system for a resupply mission to Phobos (1989)
    In:  CASI
    Details
    Publication Date: 2017-03-17
    Description: For a long-term mission in space, a propulsion system with a high specific impulse and low mass must be designed. The system must also be safe in terms of human lives and must be cost efficient to a degree. The main focus is to design a direct nuclear propulsion system for a resupply mission to Phobos from an orbiting Earth space station and return. The design considered is an annular, packed particle bed nuclear reactor with hydrogen used as the reflector, moderator, coolant, and propellant. The use of hydrogen in all these areas helps reduce the total mass, since the amount of hydrogen required is only that needed for propulsion. The mass of hydrogen required for propulsion is reduced by using a direct nuclear propulsion system with a high specific impulse relative to a hydrogen oxygen system. Certain calculations were not looked at in great detail. This included the aerospace details of the mission. Most of the numbers for this section were found in tables and taken to be correct without extensive calculations. The main objective of the project was to study the thermohydraulic and neutronic aspects of the reactor.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: USRA, NASA(USRA University Advanced Design Program Fifth Annual Summer Conference; p 195-200
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  • 8
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    Concepts for space maintenance of OTV engines (1986)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Concepts for space maintainability of the Orbital Transfer Vehicle (OTV) engines are examined. An engine design is developed which is driven by space maintenance requirements and by a failure modes and effects analysis (FMEA). Modularity within the engine is shown to offer cost benefits and improved space maintenance capabilities. Space-operable disconnects are conceptualized for both engine change-out and for module replacement. A preliminary space maintenance plan is developed around a controls and condition monitoring system using advanced sensors, controls, and condition monitoring concepts.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: Johns Hopkins Univ., The 1986 JANNAF Propulsion Meeting, Volume 1; p 99-110
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  • 9
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    Orbit Transfer Rocket Engine Technology Program: Advanced engine study, task D.1/D.3 (1986)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Concepts for space maintainability of OTV engines were examined. An engine design was developed which was driven by space maintenance requirements and by a failure mode and effects (FME) analysis. Modularity within the engine was shown to offer cost benefits and improved space maintenance capabilities. Space operable disconnects were conceptualized for both engine change-out and for module replacement. Through FME mitigation the modules were conceptualized to contain the least reliable and most often replaced engine components. A preliminary space maintenance plan was developed around a controls and condition monitoring system using advanced sensors, controls, and condition monitoring concepts. A complete engine layout was prepared satisfying current vehicle requirements and utilizing projected component advanced technologies. A technology plan for developing the required technology was assembled.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA-CR-175084 , NAS 1.26:175084 , RI/RD86-116
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  • 10
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    Orbit transfer rocket engine technology program. Phase 2: Advanced engine study (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: In Phase 2 of the Advanced Engine Study, the Failure Modes and Effects Analysis (FMEA) maintenance-driven engine design, preliminary maintenance plan, and concept for space operable disconnects generated in Phase 1 were further developed. Based on the results of the vehicle contractors Orbit Transfer Vehicle (OTV) Concept Definition and System Analysis Phase A studies, minor revisions to the engine design were made. Additional refinements in the engine design were identified through further engine concept studies. These included an updated engine balance incorporating experimental heat transfer data from the Enhanced Heat Load Thrust Chamber Study and a Rao optimum nozzle contour. The preliminary maintenance plan of Phase 1 was further developed through additional studies. These included a compilation of critical component lives and life limiters and a review of the Space Shuttle Main Engine (SSME) operations and maintenance manual in order to begin outlining the overall maintenance procedures for the Orbit Transfer Vehicle Engine and identifying technology requirements for streamlining space-based operations. Phase 2 efforts also provided further definition to the advanced fluid coupling devices including the selection and preliminary design of a preferred concept and a preliminary test plan for its further development.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA-CR-179602 , NAS 1.26:179602 , RI/RD-87-126
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