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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 739 records · Page 41

Enhanced methanol production from photothermal CO 2 reduction via multilevel interface design

Photothermal CO 2 hydrogenation is a promising route to produce methanol as a sustainable liquid solar fuel. However, most existing catalysts require a combination of solar irradiation and additional heat input to achieve a satisfactory reaction rate. For the few that can be driven solely by light, their reaction rates are one order of magnitude lower. We develop a photothermal catalyst with multilevel interfaces that achieves improved methanol production from photothermal CO 2 hydrogenation without external heat. The catalyst features a layered structure comprising Cu/ZnO/Al 2 O 3 (CZA) covered by oxidized carbon black (oCB), where the oCB/CZA interface promotes efficient heat generation and transfer, and the Cu/oxide interface contributes to high catalytic activity. Under a mild pressure of 8 bar, our oCB/CZA catalyst shows a methanol selectivity of 64.7% with a superior production rate of 4.91 mmol·g cza −1 ·h −1 , at least one order of magnitude higher than other photothermal catalysts solely driven by light. This work demonstrates a photothermal catalyst design strategy for liquid solar fuel production.

CO2 hydrogenation↗

Planar Collisionless Shock Simulations with the Semi-implicit Particle-in-cell Model FLEKS

This study investigates the applicability of the semi-implicit particle-in-cell code FLexible Exascale Kinetic Simulator (FLEKS) to heliospheric shock simulations. We examine one- and two-dimensional local planar shock simulations, initialized using MHD states with upstream conditions representative of plasmas in the hypersonic, β ∼ 1 regime, for both quasi-perpendicular and quasi-parallel configurations. The refined algorithm in FLEKS proves robust, enabling accurate shock simulations with a grid resolution on the order of the electron inertial length d e . Our simulations successfully capture key shock features, including shock structures (foot, ramp, overshoot, and undershoot), upstream and downstream waves (fast magnetosonic, whistler, Alfvén ion-cyclotron, and mirror modes), and non-Maxwellian particle distributions. Crucially, we find that at least two spatial dimensions are critical for accurately reproducing downstream-wave physics in quasi-perpendicular shocks and capturing the complex dynamics of quasi-parallel shocks, including surface rippling, shocklets, short, large-amplitude magnetic structures, magnetic reconnection, and jets. Furthermore, our parameter studies demonstrate the impact of mass ratio and grid resolution on shock physics. This work provides valuable guidance for selecting appropriate physical and numerical parameters for shock simulations using a semi-implicit PIC method, paving the way for incorporating kinetic shock processes into large-scale collisionless plasma simulations with the MHD-AEPIC model.

plasma astrophysics↗

The mechanical design of the horn-reflector antenna and radome

This paper describes the mechanical design of the horn-reflector antenna and the associated radome. The mechanical considerations dictating the final configuration of the antenna structure are discussed, along with the engineering aspects of the design, fabrication, and erection of the structure. The mechanical features of the data take-off and antenna drive systems are given in detail. The final section presents an account of the requirements, manufacture, and installation of the radome and its accessory equipment.

HORN ANTENNA↗

The structure of a sunspot. III.

Sunspot structure model explaining features of Wilson effect, using intensity profiles from microphotometer tracings across photographs during passage across disk

Cannon, C. J.↗

Mariner Mars 1969 - Atmospheric results

Mars atmospheric data from Mariner flights, discussing north polar haze, bright surface features morphology, multiring structures and water vapor exchange

Leighton, R. B.↗

The Nimbus image dissector camera system - An evaluation of its meteorological applications.

Brief description of the electronics and operation of the Nimbus image dissector camera system (IDCS). The geometry and distortions of the IDCS are compared to the conventional AVCS camera on board the operational ITOS and ESSA satellites. The unique scanning of the IDCS provides for little distortion of the image, making it feasible to use a strip grid for the IDCS received in real time by local APT stations. The dynamic range of the camera favors the white end (high reflectance) of the gray scale. Thus, the camera is good for detecting cloud structure and ice features through brightness changes. Examples of cloud features, ice, and snow-covered land are presented. Land features, on the other hand, show little contrast. The 2600 x 2600 km coverage by the IDCS is adequate for the early detection of weather systems which may affect the local area. An example of IDCS coverage obtained by an APT station in midlatitudes is presented.

Sabatini, R. R.↗

Experiments on confined turbulent jets in cross flow.

Results are reported of experiments on the effects of an opposite wall on the characteristics of turbulent jets injected into a cross flow, for unheated and heated jets. Longitudinal and transverse distributions of velocity and temperature are presented for single and multiple circular jets, and trajectories are presented for two-domensional jets. The opposite wall has relatively little effect on a single jet unless the ratio of jet to cross flow momentum flux is large enough for the jet to impinge on the opposite wall. For a row of jets aligned perpendicularly to the cross flow, the opposite wall exerts progressively larger influence as the spacing between jets decreases. Much of the effect of jet and wall proximity can be understood by considering the interaction of the vortex flow which is the major feature of the structure of a single jet in a cross flow. Smoke photographs are shown to elucidate some of the interaction patterns.

Kamotani, Y.↗

A new model for cometary nuclei.

A new model for the nucleus of comets is presented, hypothesizing formation at large heliocentric distances from many independent solid bodies. It is shown that such a configuration would collapse to a single assemblage if it is to survive into the inner solar system. Prior to collapse, the bodies would be subject to coating by interstellar gas and particles, which would form the material lost into the coma at subsequent inner solar system perihelia. Quantitative estimates place an upper limit to the body sizes of 2.3 m and a lower limit of the number as 3 x 10 to the 10th power with sizes of a few tenths of a micron and numbers of about 10 to the 33rd power most probable. The major structural and evolutionary features of such comet nuclei are consistent with the Whipple icy-conglomerate model.

O'Dell, C. R.↗

Scanning electron microscopy of the vestibular end organs

The vestibular end organs, after chemical fixation, were freeze dried, coated with gold and palladium, and studied in the scanning microscope. Scanning microscopy gives a good three dimensional view of the sensory areas and allows study of both gross anatomy and microstructures. Cross anatomical features of the structure of the ampullae are demonstrated. The form of the statoconia in different species of animals is shown. New aspects of the structure of the sensory hairs are revealed. The hair bundles in the central areas of the cristae and in the striola of the maculae differ structurally from the hair bundles at the periphery of the sensory regions. Furthermore, some hair bundles consisting of very short stereocilia were observed. The relationship between the cupula and the statoconial membrane to the epithelial surface is discussed.

Lindeman, H. H.↗

Experiments on confined turbulent jets in cross flow

Results are reported of experiments on the effects of an opposite wall on the characteristics of turbulent jets injected into a cross flow, for unheated and heated jets. Longitudinal and transverse distributions of velocity and temperature are presented for single and multiple circular jets, and trajectories are presented for two-dimensional jets. The opposite wall has relatively little effect on a single jet unless the ratio of jet to cross flow momentum flux is large enough for the jet to impinge on the opposite wall. For a row of jets aligned perpendicularly to the cross flow, the opposite wall exerts progressively larger influence as the spacing between jets decreases. Much of the effect of jet and wall proximity can be understood by considering the interaction of the vortex flow which is the major feature of the structure of a single jet in a cross flow. Smoke photographs are shown to elucidate some of the interaction patterns.

Kamotani, Y.↗

Satellite geological and geophysical remote sensing of Iceland

The author has identified the following significant results. Rhyolitic rocks in the Torfajokull geothermal area and geothermally altered ground in the Torfajokull and Reykjanes geothermal areas can also be delineated. The fallout pattern of tephra from the 1970 eruption from the volcano Hekla can be mapped where sufficient depth of deposition destroyed the vegetation. Standard NDPF 70mm negatives (3rd generation) were used to print enlargements of the volcanic islands of Surtsey and Heimaey. Sufficient resolution is maintained to directly update maps to the 1:100,000 scale. Low-sun angle imagery ( 10 deg) of Iceland has been particularly valuable in mapping new structural and volcanic features hidden beneath glacialic ice in Iceland's neovolcanic zone. ERTS-1 imagery has shown the marked differences in volcanic landforms in Iceland from a regional viewpoint. The regional distribution of crater rows, moberg ridges, table (moberg) mountains, calderas, central volcanoes, and shield volcanoes shows striking differences in volcanic geomorphology in different parts of Iceland's neovolcanic zone.

Williams, R. S., Jr.↗

Interdisciplinary applications and interpretations of ERTS data within the Susquehanna River basin

The author has identified the following significant results. The full potential of high quality data is achieved only with the application of efficient and effective interpretation techniques. An excellent operating system for handling, processing, and interpreting ERTS-1 and other MSS data was achieved. Programs for processing digital data are implemented on a large nondedicated general purpose computer. Significant results were attained in mapping land use, agricultural croplands, forest resources, and vegetative cover. Categories of land use classified and mapped depend upon the geographic location, the detail required, and the types of lands use of interest. Physiographic and structural provinces are spectacularly displayed on ERTS-1 MSS image mosaics. Geologic bedrock structures show up well and formation contacts can sometimes be traced for hundreds of kilometers. Large circular structures and regional features, previously obscured by the detail of higher resolution data, can be seen. Environmental monitoring was performed in three areas: coal strip mining, coal refuse problems, and damage to vegetation caused by insects and pollution.

Mcmurtry, G. J.↗

A candidate mission using the Shuttle and solar electric propulsion

It is suggested that an out-of-the-ecliptic solar electric propulsion (SEP) mission be performed. Data would be gathered pertaining to the three-dimensional structure of solar features at radio and X-ray wavelengths, the properties of the solar wind as a function of latitude and time, the configuration of the interplanetary field and its relation to solar fields, and the modulations of cosmic rays to determine the spectrum of interstellar cosmic rays. The mission would also, it is thought, demonstrate the capability of SEP for use in Shuttle missions. The SEP spacecraft and the ongoing development of related systems are examined. The weight of a SEP stage is contrasted with the weight of a chemical rocket stage.

Duxbury, J. H.↗

Satellite geological and geophysical remote sensing of Iceland

The author has identified the following significant results. The ERTS imagery has sufficient resolution to map, from MSS color composites, areas of altered ground caused by high temperature geothermal activity at the Namafjall, Torfajokull, and Reykjanes geothermal areas. The major axes of the fallout pattern of tephra from the May - July 1970 volcanic eruption from Hekla Volcano can be mapped where sufficient depth of deposition was present to seriously affect the normal vegetation. Lava flows from the 1961 volcanic eruption at Askja; some of the lava flows from the 1947-48 eruption, and and all of the lava flows from the 1970 eruption at Hekla; and the areas covered by tephra and lava from the 1973 eruption on Heimaey could be delineated. Low sun angle imagery of less than 10 deg of snow covered terrain was particularly valuable in mapping structural and volcanic features concealed beneath glacial ice in the active volcanic zones of Iceland.

Williams, R. S., Jr.↗

Can acoustic emission detect the initiation of fatigue cracks: Application to high-strength light alloys used in aeronautics

Acoustic emission was used for the detection of fatigue cracking in a number of high-strength light alloys used in aeronautical structures. Among the features studied were: the influence of emission frequency, the effect of surface oxidation, and the influence of grains. It was concluded that acoustic emission is an effective nondestructive technique for evaluating the initiation of fatigue cracking in such materials.

Bathias, C.↗

Coronal gas in the Galaxy. I - A new survey of interstellar O VI

Ultraviolet spectra of 40 O- and B-type stars have been intensively scanned in the vicinity of the O VI transitions at 1032 and 1038 A with the Copernicus satellite. This survey of the high-temperature (log T about 5.5) phase of interstellar gas is an extension of the earlier observations of interstellar O VI by Jenkins and Meloy (1974), bringing the total coverage up to 72 stars. Except for a few distant stars, the overall quality of the present data surpasses that of the earlier work. Plots of absorption optical depths versus radial velocity are presented for both transitions in each star. Total column densities (or their upper limits), velocity centroids, and velocity widths have been extracted from the profiles and tabulated, with the results of Jenkins and Meloy (1974) included. Qualitatively, the highly variable O VI densities and velocities seem to exhibit no systematic patterns or regional trends; there is no recognizable correlation in the behavior of coronal gas with pronounced features of galactic structure.

Jenkins, E. B.↗

The 1st generation low cost point focus solar concentrator

A point focus solar concentrator that, given a high volume of production, will optimize the ratio of performance to cost is considered. The concentrator design approach has evolved by a systematic process of examining the operating requirements particular to the solar application, minimizing material content through detail structural design and structurally efficient subsystem features, and utilizing materials and processes compatible with high volume production techniques. The design approach, the rationale for the configuration and subsystem selections, and the development status are described.

Zimmerman, J.↗