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  • General Chemistry  (77,717)
  • ENERGY PRODUCTION AND CONVERSION
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  • 1
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    Quantification of bone surface textures: exploring a new method of ontogenetic ageing (2023)
    In:  Journal of Analytical Science and Technology vol. 14 no. 1
    Details
    Publication Date: 2024-02-26
    Description: Identifcation of ontogenetic age classes plays an important role in the felds of zoology, palaeontology and archaeology, where accurate age classifcations of (sub)fossil remains are a crucial component for the reconstruction \nof past life. Textural ageing\xe2\x80\x94the identifcation of age-related bone surface textures\xe2\x80\x94provides a size-independent \nmethod for age assessment of vertebrate material. However, most of the work so far is limited to qualitative results. \nWhile qualitative approaches provide helpful insights on textural ageing patterns, they are heavily subject to observer \nbias and fall short of quantitative data relevant for detailed statistical analyses and cross-comparisons. Here, we present a pilot study on the application of 3D surface digital microscopy to quantify bone surface textures on the long \nbones of the grey heron (Ardea cinerea) and the Canada goose (Branta canadensis) using internationally verifed \nroughness parameters. Using a standardised measuring protocol, computed roughness values show a strong correlation with qualitative descriptions of textural patterns. Overall, higher roughness values correspond to increased numbers of grooves and pits and vice versa. Most of the roughness parameters allowed distinguishing between diferent \nontogenetic classes and closely followed the typical sigmoidal animal growth curve. Our results show that bone \ntexture quantifcation is a feasible approach to identifying ontogenetic age classes.
    Keywords: General Physics and Astronomy ; General Environmental Science ; General Biochemistry ; Genetics and Molecular Biology ; General Materials Science ; General Chemistry ; Roughness ; Surfaces ; Taphonomy ; Topography ; Bone ; Ontogeny ; Digital microscopy
    Repository Name: National Museum of Natural History, Netherlands
    Type: info:eu-repo/semantics/article
    Format: application/pdf
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  • 2
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    NASA specification for manufacturing and performance requirements of NASA standard aerospace nickel-cadmium cells (1988)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: On November 25, 1985, the NASA Chief Engineer established a NASA-wide policy to maintain and to require the use of the NASA standard for aerospace nickel-cadmium cells and batteries. The Associate Administrator for Safety, Reliability, Maintainability, and Quality Assurance stated on December 29, 1986, the intent to retain the NASA standard cell usage policy established by the Office of the Chief Engineer. The current NASA policy is also to incorporate technological advances as they are tested and proven for spaceflight applications. This policy will be implemented by modifying the existing standard cells or by developing new NASA standards and their specifications in accordance with the NASA's Aerospace Battery Systems Program Plan. This NASA Specification for Manufacturing and Performance Requirements of NASA Standard Aerospace Nickel-Cadmium Cells is prepared to provide requirements for the NASA standard nickel-cadmium cell. It is an interim specification pending resolution of the separator material availability. This specification has evolved from over 15 years of nickel-cadmium cell experience by NASA. Consequently, considerable experience has been collected and cell performance has been well characterized from many years of ground testing and from in-flight operations in both geosynchronous (GEO) and low earth orbit (LEO) applications. NASA has developed and successfully used two standard flight qualified cell designs.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NHB-8073.1 , NAS 1.18:8073.1
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    NASA TECHNICAL REPORTS
  • 3
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    Experimental determination of in situ utilization of lunar regolith for thermal energy storage (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-08-28
    Description: A Lunar Thermal Energy from Regolith (LUTHER) experiment has been designed and fabricated at the NASA Lewis Research Center to determine the feasibility of using lunar soil as thermal energy storage media. The experimental apparatus includes an alumina ceramic canister which contains simulated lunar regolith, a heater, nine heat shields, a heat transfer cold jacket, and 19 type-B platinum rhodium thermocouples. The simulated lunar regolith is a basalt that closely resembles the lunar basalt returned to earth by the Apollo missions. The experiment will test the effects of vacuum, particle size, and density on the thermophysical properties of the regolith, which include melt temperature, specific heat thermal conductivity, and latent heat of storage. Two separate tests, using two different heaters, will be performed to study the effect of heating the system using radiative and conductive heat transfer. A finite differencing SINDA model was developed at NASA Lewis Research Center to predict the performance of the LUTHER experiment. The code will predict the effects of vacuum, particle size, and density has on the heat transfer to the simulated regolith.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: In: IECEC '92; Proceedings of the 27th Intersociety Energy Conversion Engineering Conference, San Diego, CA, Aug. 3-7, 1992. Vol. 4 (A93-25851 09-44); p. 4.183-4.188.
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  • 4
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    Material properties and device evaluations of ECR-deposited a-Si:H and a-SiC:H films (1991)
    In:  Other Sources
    Details
    Publication Date: 2019-08-28
    Description: Device-quality a-Si:H and a-SiC:H films have been deposited using electron cyclotron resonance (ECR) microwave plasmas of SiH4, CH4, and H2 mixtures. Typical material properties of ECR-deposited, photosensitive a-Si:H films are: (1) high photosensitivity up to 2 x 106 with a photoconductivity of 10 exp -5 to 10 exp -4/(Ohm-cm), (2) a Tauc gap of 1.75 to 1.85 eV, (3) an Urbach slope of 50-60 meV determined by the constant photocurrent method, and (4) an integrated defect density of 1-2 x 10 exp 16/cu cm determined by junction capacitance measurements. Highly conductive, p-type a-SiC:H films have been produced by ECR plasmas with a conductivity of 0.2/(Ohm-cm).
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: IEEE Photovoltaic Specialists Conference; Oct 07, 1991 - Oct 11, 1991; Las Vegas, NV; United States
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    NASA TECHNICAL REPORTS
  • 5
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    Performance projections of alternative AMTEC systems and devices (1991)
    In:  Other Sources
    Details
    Publication Date: 2019-08-28
    Description: The alkali metal thermoelectric converted (AMTEC) converts heat to electrical power without moving parts. Attention is presently given to two AMTEC devices that have been optimized for conversion efficiencies of the order of 30 percent or more at 1100 K, in conjunction with high volumetric power densities. A 'tube-bundle' AMTEC configuration yields a peak power of 426 W/l; a flat-plate AMTEC system yields 2.4 W/l.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: In: Space nuclear power systems; Proceedings of the 8th Symposium, Albuquerque, NM, Jan. 6-10, 1991. Pt. 1 (A93-13751 03-20); p. 472-481.
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    NASA TECHNICAL REPORTS
  • 6
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    Thermal mathematical modeling of a multicell common pressure vessel nickel-hydrogen battery (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-08-28
    Description: A two-dimensional and time-dependent thermal model of a multicell common pressure vessel (CPV) nickel-hydrogen battery was developed. A finite element solver called PDE/Protran was used to solve this model. The model was used to investigate the effects of various design parameters on the temperature profile within the cell. The results were used to help find a design that will yield an acceptable temperature gradient inside a multicell CPV nickel-hydrogen battery. Steady-state and unsteady-state cases with a constant heat generation rate and a time-dependent heat generation rate were solved.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Electrochemical Society, Journal (ISSN 0013-4651); 139; 10; p. 2781-2787.
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    NASA TECHNICAL REPORTS
  • 7
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    Advances in high temperature components for AMTEC (Alkali Metal Thermal-to-Electric Converter) (1991)
    In:  Other Sources
    Details
    Publication Date: 2019-08-28
    Description: The basic performance of Alkali Metal Thermal-to-Electric Converter (AMTEC) cells is well understood, and quantitative modeling of the electrode performance has been carried out. Tests have been carried out to evaluate the high temperature performance of critical AMTEC components. Progress made in understanding the relative performance of AMTEC components, such as electrodes, electrolytes, working fluids, and seals, as device operating temperature is varied is discussed. Most metallic components are especially subject to corrosion in hot liquid alkali metals containing dissolved oxides. Stability issues of AMTEC components may be addressed by life testing, accelerated testing, and modeling based on known kinetic and thermochemical data.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: IECEC ''91: Intersociety Energy Conversion Engineering Conference; Aug 04, 1991 - Aug 09, 1991; Boston, MA; United States
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    NASA TECHNICAL REPORTS
  • 8
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    Solar cells for lunar applications by vacuum evaporation of lunar regolith materials (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-08-28
    Description: The possibility of the direct fabrication of solar cells on the lunar surface by the vacuum evaporation of lunar regolith is examined as an alternative approach to electric power generation on the surface of the moon. The raw materials for large-scale solar cell growth could be available from the waste products generated in regolith processing for volatiles collection and oxygen extraction. The production of vast areas of solar cells can be implemented through a self-generation process whereby the power generated by grown cells is used to produce more cells.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: IAF PAPER 92-0158
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    NASA TECHNICAL REPORTS
  • 9
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    Beamed microwave power transmission and its application to space (1992)
    In:  Other Sources
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    Publication Date: 2019-08-28
    Description: The general principles and special components of beamed microwave power transmission systems are outlined and their application to the space program are discussed. The beamed system is defined as starting with a dc source of power at the transmitting end, converting it to a microwave beam for transmission through space, and ending with the dc power output at the receiving end. An experimentally measured and certified dc-to-dc efficiency of 54 percent has been achieved, using this definition. The application discussed is that of a LEO to GEO transportation system that depends upon vehicles propelled by electric thrusters whose power is supplied by a microwave beam originating at the earth's surface. The advantages of the all-electronic system over a chemically propelled system are enumerated. The principles of space propulsion, particularly as they relate to electric propulsion, are outlined. Key components of the system and environmental considerations are discussed.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: IEEE Transactions on Microwave Theory and Techniques (ISSN 0018-9480); 40; 6, Ju; 1239-125
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    NASA TECHNICAL REPORTS
  • 10
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    Martian resource utilization. 1: Plant design and transportation selection criteria (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-08-28
    Description: Indigenous Space Materials Utilization (ISMU) provides an opportunity to make Mars exploration mission scenarios more affordable by reducing the initial mass necessary in Low Earth Orbit (LEO). Martian propellant production is discussed in terms of simple design and economic tradeoffs. Fuel and oxidizer combinations included are H2/O2, CH4/O2, and CO/O2. Process flow diagrams with power and mass flow requirements are presented for a variety of processes, and some design requirements are derived. Maximum allowable plant masses for single use amortization are included.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Space Power - Resources, Manufacturing and Development (ISSN 0883-6272); 11; 4-Mar; p. 343-373
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    NASA TECHNICAL REPORTS
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