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  • 1
    Publication Date: 2015-02-27
    Description: Porphyry dikes and hydrothermal veins from the porphyry Cu-Mo deposit at Butte, Montana, contain multiple generations of quartz that are distinct in scanning electron microscope-cathodoluminescence (SEM-CL) images and in Ti concentrations. A comparison of microprobe trace element profiles and maps to SEM-CL images shows that the concentration of Ti in quartz correlates positively with CL brightness but Al, K, and Fe do not. After calibrating CL brightness in relation to Ti concentration, we use the brightness gradient between different quartz generations as a proxy for Ti gradients that we model to determine time scales of quartz formation and cooling. Model results indicate that time scales of porphyry magma residence are ~1,000s of years and time scales from porphyry quartz phenocryst rim formation to porphyry dike injection and cooling are ~10s of years. Time scales for the formation and cooling of various generations of hydrothermal vein quartz range from 10s to 10,000s of years. These time scales are considerably shorter than the ~0.6 m.y. overall time frame for each porphyry-style mineralization pulse determined from isotopic studies at Butte, Montana. Simple heat conduction models provide a temporal reference point to compare chemical diffusion time scales, and we find that they support short dike and vein formation time scales. We interpret these relatively short time scales to indicate that the Butte porphyry deposit formed by short-lived episodes of hydrofracturing, dike injection, and vein formation, each with discrete thermal pulses, which repeated over the ~3 m.y. generation of the deposit.
    Print ISSN: 0361-0128
    Topics: Geosciences
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  • 2
    Publication Date: 2015-02-24
    Print ISSN: 0361-0128
    Electronic ISSN: 1554-0774
    Topics: Geosciences
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  • 3
    Publication Date: 2018-06-21
    Description: Existing literature on economic growth and structural change relies on trade data to make pronouncements about a country's competitiveness and long-term growth prospects through the acquisition of capabilities. However, insufficient data give us a limited view of what is happening within the domestic economy, and how the development of manufacturing through links in the production process leads to the export of intermediate or final products. Using input-output data, this paper devises an agglomeration indicator to measure economic diversification and to compare Bangladesh with other key economies. In the process, we shed light on the symbiotic relationship between manufacturing and services as the country develops. Despite Bangladesh's astounding growth over the past 15 years, diversification has been somewhat slower than expected for its level of development.
    Keywords: D24 ; D57 ; F15 ; O14 ; ddc:330 ; Bangladesh ; business services ; economic diversification ; global value chains ; input-output tables ; ready-made garments ; structural transformation
    Repository Name: EconStor: OA server of the German National Library of Economics - Leibniz Information Centre for Economics
    Language: English
    Type: doc-type:workingPaper
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  • 4
    Publication Date: 2018-12-01
    Description: Supercritical technology has been applied to the design of a forward-swept-wing fighter configuration, and an assessment has been made of the relative performance of forward versus aft sweep. The wing and canard for this forward-swept wing configuration were designed for transonic maneuver by the use of a transonic computational analysis method and a transonic design procedure. The computational method calculates the transonic flow over a canard-wing-fuselage combination so that the strong transonic induced-flow effects of the canard on the wing are taken into account. A model of this configuration was constructed and was tested in the Langley 16-Foot Transonic Tunnel. The transonic theory gave a reasonably good estimate of the wing pressure distributions at transonic maneuver conditions. Comparison of this configuration with an equivalent aft-swept wing configuration showed that, at a Mach number of 0.9 and a lift coefficient of 0.9, the two configurations have essentially the same drag. This forward-swept wing configuration was also found to have very good maneuver performance relative to the Rockwell International HiMAT highly-maneuverable aircraft configuration.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: AIAA PAPER 85-4069
    Format: text
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  • 5
    Publication Date: 2013-08-31
    Description: Fiber optic delivery systems promise to extend the application of holography to severe environments by simplifying test configurations and permitting the laser to be remotely placed in a more benign location. However, the introduction of optical fiber leads to phase stability problems. Environmental effects cause the pathlengths of the fibers to change randomly, preventing the formation of stationary interference patterns which are required for holography. An active phase control system has been designed and used with an all-fiber optical system to stabilize the phase difference between light emitted from two fibers, and to step the phase difference by 90 deg without applying any constraints on the placement of the fibers. The accuracy of the phase steps is shown to be better than 0.02 deg., and a stable phase difference can be maintained for 30 min. This system can be applied to both conventional and electro-optic holography, as well as to any system where the maintenance of an accurate phase difference between two coherent beams is required.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: E-4277 , NASA-TM-101295 , NAS 1.15:101295
    Format: application/pdf
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  • 6
    Publication Date: 2013-08-31
    Description: A transonic computational analysis method and a transonic design procedure have been used to design the wing and the canard of a forward-swept-wing fighter configuration for good transonic maneuver performance. A model of this configuration was tested in the Langley 16-Foot Transonic Tunnel. Oil-flow photographs were obtained to examine the wind flow patterns at Mach numbers from 0.60 to 0.90. The transonic theory gave a reasonably good estimate of the wing pressure distributions at transonic maneuver conditions. Comparison of the forward-swept-wing configuration with an equivalent aft-swept-wing-configuration showed that, at a Mach number of 0.90 and a lift coefficient of 0.9, the two configurations have the same trimmed drag. The forward-swept wing configuration was also found to have trimmed drag levels at transonic maneuver conditions which are comparable to those of the HiMAT (highly maneuverable aircraft technology) configuration and the X-29 forward-swept-wing research configuration. The configuration of this study was also tested with a forebody strake.
    Keywords: AERODYNAMICS
    Type: NASA-TP-2628 , NAS 1.60:2628 , L-16120
    Format: application/pdf
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  • 7
    Publication Date: 2013-08-31
    Description: The equations used by the 16 foot transonic tunnel in the data reduction programs are presented in eight modules. Each module consists of equations necessary to achieve a specific purpose. These modules are categorized in the following groups: tunnel parameters; jet exhaust measurements; skin friction drag; balance loads and model attitudes calculations; internal drag (or exit-flow distributions); pressure coefficients and integrated forces; thrust removal options; and turboprop options. This document is a companion document to NASA TM-83186, A User's Guide to the Langley 16 Foot Transonic Tunnel, August 1981.
    Keywords: RESEARCH AND SUPPORT FACILITIES (AIR)
    Type: NASA-TM-86319-REV-1 , NAS 1.15:86319-REV-1
    Format: application/pdf
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  • 8
    Publication Date: 2013-08-31
    Description: A wind tunnel investigation was conducted to study the application of supercritical technology to highly maneuverable combat aircraft. The configuration studied has a leading-edge sweep of 45 deg and an aspect ratio of 3.28. Two supercritical-wing shapes were tested at Mach numbers from 0.60 to 0.95 with angles of attack from -2 deg to 17 deg. On supercritical wing was designed to achieve a high level of transonic maneuver performance at a Mach number of 0.90; however, excessive flow separation developed on this wing at a Mach number of 0.85. A second supercritical wing was tested which had significantly reduced flow separation and improved drag characteristics at a Mach number of 0.85 and maintained the performance of the original wing at the higher Mach numbers. Leading-edge vortex generators did not improve the performance of the second wing; however, a sharp leading-edge flap produced sizable drag reductions at Mach numbers from 0.60 to 0.90.
    Keywords: AERODYNAMICS
    Type: NASA-TM-84513 , NAS 1.15:84513 , L-15399
    Format: application/pdf
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  • 9
    Publication Date: 2013-08-31
    Description: Numerical procedures to compute gradients in aerodynamic loading due to planform shape changes using panel method codes were studied. Two procedures were investigated: one computed the aerodynamic perturbation directly; the other computed the aerodynamic loading on the perturbed planform and on the base planform and then differenced these values to obtain the perturbation in loading. It is indicated that computing the perturbed values directly can not be done satisfactorily without proper aerodynamic representation of the pressure singularity at the leading edge of a thin wing. For the alternative procedure, a technique was developed which saves most of the time-consuming computations from a panel method calculation for the base planform. Using this procedure the perturbed loading can be calculated in about one-tenth the time of that for the base solution.
    Keywords: STRUCTURAL MECHANICS
    Type: FLOW-RR-186 , NASA-CR-3489
    Format: application/pdf
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  • 10
    Publication Date: 2013-08-31
    Description: A partial accounting of Apollo Orbital Science Photographic Team (APST) work is presented as reported by one of its members who provided scientific recommendations for, guidance in, and reviews of photography in astronomy. Background on the formation of the team and its functions and management are discussed. It is concluded that the APST clearly performed the overall objective for which it was established - to improve the scientific value of the Apollo lunar missions. Specific reasons for this success are given.
    Keywords: SPACE SCIENCES
    Type: NASA-CR-137376
    Format: application/pdf
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