Search NASA⌕ Search

SEARCH · Search NASA

Results for “Texture”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 469 records · Page 26
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Quantitative characterization of gradient microstructures: A study on friction stir spot processing of pure cobalt

Heterogeneous microstructures in polycrystalline metals can enhance the strength and ductility, outperforming homogeneous structures of similar composition. This study investigates deformed cobalt via friction stir spot processing with varying dwell times to uncover the effects of plastic deformation and heat generation on the formation of morphological, phase, and grain boundary character gradients. A new approach to quantify the morphological gradients in materials, which describes grain morphology in terms of density followed by parametric regression, enables direct quantification of processing depth and gradient sharpness. Results show that longer processing times increase the steepness of morphological gradients and reduce the deformation depth for friction stir spot processing with low plunge depths and high tool rotational speeds. The amount of retained FCC is increased in the shorter processing conditions, primarily due to refined grain size, increased defect content, and reduced heat generation. Crystallographic texture analysis of the HCP phase indicated a dominant B-fiber described by (0001) ∥ shear plane normal in the extreme processing conditions and the formation of a P-fiber, shear direction ∥ ⟨11$\bar2$0⟩ for intermediate dwell times. The texture of the FCC phase for low processing times was a C texture {100}⟨011⟩ where longer processing times were dominated by a [001] fiber texture with a main {110}⟨100⟩ orientation and emergence of a slight [111] fiber in the longest processing condition. The approaches outlined in this work give insight into quantifying gradients and improve the understanding of highly deformed cobalt.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Lipids represent a dynamic, yet stable pool of microbially-derived soil carbon

There is an emerging consensus that microorganisms are a primary source of persistent, slow-cycling soil organic matter (SOM), however which microbial residues contribute to SOM and what controls their accumulation remains unresolved. Lipids are a commonly overlooked biomolecular pool that could contribute significantly to stable SOM. While current estimates for phospholipid degradation in soils are rapid, lipids are structurally heterogeneous molecules that could turnover at different rates. Through a year-long soil incubation and compound-specific, stable isotope probing (SIP)-lipidomics, we were able to rigorously track the persistence of lipid compounds in silty and sandy switchgrass bioenergy crop soils. Here, we assessed the influence of lipid structure on soil lipid accrual and degradation as moderated by soil texture, since mineral association is presumed to be the primary mechanism for lipid persistence. After rapid incorporation of 13 C glucose into microbial biomass, we found 13 C label was retained broadly across chemically diverse lipid classes, even after one year. 13 C-labeled lipid profiles varied significantly with soil texture; however, we found no difference between sandy and silty soils in lipid retention, suggesting soil texture may only play a minor role in modulating lipid persistence. Only two lipid subclasses were found to be persistent (i.e., retention of 13 C label without significant degradation or production): phosphatidylinositol lipids and hydroxyceramide lipids, both of which are negatively charged, possibly facilitating stabilization by mineral complexation. However, several other subclasses displayed substantial ongoing production. In particular, the accumulation of triacylglycerol lipids across soil textures suggests that storage lipids may be an important component of SOC, highlighting a potential target for management strategies to promote C retention by lipid accrual. Overall, the retention for over a year of 13 C label in microbial intact lipid biomarkers reveals the importance of efficient biomass production and turnover when considering microbial C contributions to SOM.

compound-specific↗
DOE OSTI2025

Design and Control of Three-Dimensional Topological Magnetic Fields Using Interwoven Helical Nanostructures

Three-dimensional (3D) magnetic nanostructures are an emerging platform capable of creating complex topological magnetic fields. The control of localized nanoscale magnetic fields is seen to be of importance for diverse areas from bioapplications such as drug delivery, to particle trapping and controlling Majorana Fermions for quantum computing. Three-dimensional geometric confinement and proximity can create tailor-made spin textures not possible in two dimensions. The control of magnetization afforded here can allow the formation of unique stray field textures. Here, we report the creation of reconfigurable 3D topological magnetic field textures induced by an interwoven 3D nanostructure and applied field protocol. These field textures emerge due to distinct DWs formed in this structure and lead to the creation of an antivortex field, a hexapole cusp and a 3D skyrmion field tube of mixed chirality. In conclusion, our results therefore show a key step toward the design and control of topological magnetic fields on the nanoscale.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Reducing crystal symmetry to generate out-of-plane Dzyaloshinskii–Moriya interaction

The Dzyaloshinskii-Moriya antisymmetric exchange interaction (DMI) stabilises topological spin textures with promising future spintronics applications. According to crystal symmetry, the DMI can be categorized as four different types that favour different chiral textures. Unlike the other three extensively-investigated types, out-of-plane DMI, as the last type that favours in-plane chirality, remained missing so far. Here we apply point-group-dependent DMI matrix analysis to show that out-of-plane DMI exists under reduced crystal symmetry. Through strain and structure engineering, we show how C s symmetry is realized in ultrathin magnets and observe the out-of-plane DMI stabilised in-plane chirality using spin-polarized electron microscopy. Our results show that extremely low out-of-plane DMI strengths at µeV/atom are sufficient to stabilise topological spin textures, including merons and bimerons. We also demonstrate field-induced reversible control of the in-plane chirality and merons. Our findings open up untapped paths on topological magnetic textures and their potential applications.

36 MATERIALS SCIENCE↗
NASA NTRS1973

Utilization of ERTS data to detect plant diseases and nutrient deficiencies, soil types and moisture levels

The author has identified the following significant results. Findings demonstrate the feasibility of delineating major terrain features, land uses, and crop species through computerized analyses. Channel 6 appears to give the most information for making separations of this type. By enlarging satellite imagery and visually comparing this with high altitude aerial photographs, locating small terrain features and cropland areas on satellite imagery is greatly facilitated. Forest types are discernable on the 2402 imagery with a #25 filter: pine stands have dark tones, hardwood stands have light tones, and pine-hardwood have intermediate tones. No textural differences are evident on this type of imagery. However, on the 2424 imagery with #89B filter, textural differences are evident but tonal differences are absent. Areas of considerable texture are interpreted as stands of high volume while areas of suppressed texture are of low volume. The 2402 imagery with a #57 filter appears to have little information of importance in timber inventory.

Parks, W. L.↗
NASA NTRS1974

Combined spectral and spatial processing of ERTS imagery data

A general procedure is presented for extracting textural properties of blocks of image data. These features are calculated in the spatial domain, taking into account the statistical nature of texture. The procedure is based on the assumption that the texture information in an image is contained in the overall or 'average' spatial relationship which the gray tones in the image have to one another. The spatial gray-tone dependence matrix is discussed together with the spectral features used in the study and the land use classification studies conducted. The results of the study show the usefulness of using both spectral and textural characteristics of ERTS multispectral scanner data for developing classification procedures.

Haralick, R. M.↗
NASA NTRS1976

Documentation of procedures for textural/spatial pattern recognition techniques

A C-130 aircraft was flown over the Sam Houston National Forest on March 21, 1973 at 10,000 feet altitude to collect multispectral scanner (MSS) data. Existing textural and spatial automatic processing techniques were used to classify the MSS imagery into specified timber categories. Several classification experiments were performed on this data using features selected from the spectral bands and a textural transform band. The results indicate that (1) spatial post-processing a classified image can cut the classification error to 1/2 or 1/3 of its initial value, (2) spatial post-processing the classified image using combined spectral and textural features produces a resulting image with less error than post-processing a classified image using only spectral features and (3) classification without spatial post processing using the combined spectral textural features tends to produce about the same error rate as a classification without spatial post processing using only spectral features.

Haralick, R. M.↗
NASA NTRS1982

Evaluation of left ventricular assist device pump bladders cast from ion-sputtered polytetrafluorethylene mandrels

A highly thromboresistant blood contacting interface for use in implanatable blood pump is investigated. Biomaterials mechanics, dynamics, durability, surface morphology, and chemistry are among the critical consideration pertinent to the choice of an appropriate blood pump bladder material. The use of transfer cast biopolymers from ion beam textured surfaces is investigated to detect subtle variations in blood pump surface morphology using Biomer as the biomaterial of choice. The efficacy of ion beam sputtering as an acceptable method of fabricating textured blood interfaces is evaluated. Aortic grafts and left ventricular assist devices were implanted in claves; the blood interfaces were fabricated by transfer casting methods from ion beam textured polytetrafluorethylene mandrels. The mandrels were textured by superimposing a 15 micron screen mesh; ion sputtering conditions were 300 volts beam energy, 40 to 50 mA beam, and a mandrel to source distance of 25 microns.

Source record↗
NASA NTRS1982

Combined use of remote sensing and seismic observations to infer geologically recent crustal deformation, active faulting, and stress fields

Characteristic traits for earthquakes associated with strike-slip motion in Central California and the Salton Sea area, as revealed in ground based studies and LANDSAT imagery, were compared. The mapped lineaments are found to be oriented in several dominant directions. One direction is the same as the trend of the San Andreas fault. The other directions differ from area to area and may reflect the stresses of earlier geologic processes. The pattern of lineament orientations is significantly LANDSAT MSS data, SEASAT synthetic aperture radar data, and magnetic field data from the South Mountain area west of Gettysburg, Pennsylvania were registered to match each other in spatial position and merged. Pattern recognition techniques were applied to the composite data set to determine its utility in recognizing different rock types and structures in vegetated terrain around South Mountain. With the use of a texture algorithm to enhance geologic features, a classification of the entire area was made. A test of the correlation between SAR tone and texture, LANDSAT tone and texture, and magnetic field data revealed no tone or texture measures linking any two of the original data sets.

Alexander, S. S.↗
NASA NTRS1983

Electron microscopic observations of hydrogen implantation in ilmenites

Hydrogen ion beams were found to form submicrometer, bumpy textures on the surface of ilmenite grains. From this effect, it is believed that similar bumpy textures seen on lunar ilmenite, pyroxene, and olivine grains are likely to be caused by solar wind irradiation. As a consequence, the concentration of bumpy textured grains may be a useful index of surface maturity for lunar soils. An attempt was made to search for grains with these bumpy textures in interplanetary dust and lunar and meteoritic regolith breccias in order to obtain information about the duration of their exposure to the solar wind. Solar wind irradiation was simulated on natural, terrestrial ilmenite. Hydrogen ion beams were directed at small grains and polished sections which were then examined by electron microscopy.

Blanford, G. E.↗
NASA NTRS1986

Carbon and carbon-coated electrodes for multistage depressed collectors for electron-beam devices - A technology review

Various aspects of carbon and carbon-coated multistaged depressed collector (MDC) electrode technology are reviewed. The physical properties of untreated graphite electrodes, ion-textured graphite electrodes, and textured, carbon-coated copper electrodes, and surface treatment procedures for these electrodes are described. The secondary electron emissions of the three electrode types are analyzed. MDC fabrication methods are discussed. The performances of MDCs fabricated with untreated graphite electrodes, ion-textured graphite electrodes, and textured, carbon-coated copper electrodes are evaluated. MDC and TWT efficiency levels for tubes fabricated with the three materials are measured.

Curren, Arthur N.↗
NASA NTRS1987

Petrology and precursors of lithic clasts from feldspathic fragmental breccia 67975

Textures and mineral chemistry (by INAA) of five lithic clasts, including both light green and light gray clasts, from feldspathic fragmental breccia 67975 were studied. The presence of five rock types was confirmed: feldspathic microporphyritic melt breccia, metamorphosed mafic-rich melt breccia with zoned and mantled clasts, 'typical' reequilibrated lunar feldspathic granulites with granoblastic texture and homogeneous mineral chemistry, hornfels, and a recrystallized mafic-rich granulite with relict igneous texture and the composition of a ferroan anorthositic norite. The mineralogy and textural data corroborate the grouping of the light green clasts proposed by Lindstrom (1984). However, the light gray clasts do not appear to be coherent in petrologic (or chemical) characteristics; one is a plagioclase-rich, possibly monomict rock with ferroan anorthositic precursor(s), and the other represents a mixture of feldspathic granulite and ferroan anorthositic norite lithologies.

Mcgee, James J.↗
NASA NTRS1987

Development of 8 cm x 8 cm silicon gridded back solar cell for space station

The 8-cm x 8-cm gridded back cell being developed for the space station photovoltaic array is described. Modeling studies show that the beginning of life power output of 1.039 W per cell may be met by several different configurations, the most promising being either a fielded or nonfielded 2 ohm-cm planar 8-mil cell. Experimental data are presented which show that a thermal alpha of 0.63 is achievable on a planar cell but at the expense of some Isc. Planar cells are found to possess short-circuit currents which are 9 percent lower than on textured cells due to the loss of near-IR radiation by transmission through the cell. Preliminary modeling shows that the efficiency of the textured cell exceeds the planar cell by approximately 9 percent at 25 C but the situation is reversed in orbit due to the high thermal alpha of textured cells (0.82). Experimental data show that the IR absorption in textured cells can be reduced by about 3 alpha points without loss of efficiency by controlling the doping concentration in the diffused layers, thus increasing the efficiency in orbit.

Lillington, D. R.↗
NASA NTRS1987

The visual control of simulated altitude

The ability of a subject flying an experimental flight to use the different sources of visual information by looking at the vertical tracking error was investigated using a 3 (altitude) x 3 (texture) x 2 (replication) factorial design. Each subject flew these 18 flights in the same partially counterbalanced order, constructed such that there was one flight at each of the three altitudes, and over each of the three surface textures within each successive set of three flights. The three ground-surface textures used consisted of meridian, latitudinal, and square textures described by Wolpert et al. (1983). The results showed that, in displays where only splay information was available, the subjects tended to confuse lateral motion with vertical.

Johnson, Walter W.↗
NASA NTRS1990

Aeolian removal of dust from radiator surfaces on Mars

Simulated radiator surfaces made of arc-textured Cu and Nb-1 percent-Zr and ion beam textured graphite and C-C composite were fabricated and their integrated spectral emittance characterized from 300 to 3000 K. A thin layer of aluminum oxide, basalt, or iron (III) oxide dust was then deposited on them, and they were subjected to low pressure winds in the Martian Surface Wind Tunnel. It was found that dust deposited on simulated radiator surfaces may or may not seriously lower their integrated spectral emittance, depending upon the characteristics of the dust. With Al2O3 there is no appreciable degradation of emittance on a dusted sample, with basaltic dust there is a 10 to 20 percent degradation, and with Fe2O3 a 20 to 40 percent degradation. It was also found that very high winds on dusted highly textured surfaces can result in their abrasion. Degradation in emittance due to abrasion was found to vary with radiator material. Arc-textured Cu and Nb-1 percent Zr was found to be more susceptible to emittance degradation than graphite or C-C composite. The most abrasion occurred at low angles, peaking at the 22.5 deg test samples.

Gaier, James R.↗
NASA NTRS1990

Formation conditions of pyroxene-olivine and magnesian olivine chondrules

Dynamic crystallization experiments performed on a Type I and an intermediate Type II/III composition demonstrate chondrule texture is controlled by the abundance of heterogeneous nuclei. This factor is controlled by the maximum initial temperature relative to the olivine disappearance temperature for the given heating time. Glassy and excentroradial textures form from superheated melts with no nuclei, and barred textures form with initial temperatures near the olivine disappearance temperature. Porphyritic and granular textures form with initial temperatures below the liquidus with abundant nuclei. Comparison of zoning characteristics of experimental olivines with those in natural porphyritic olivine chondrules indicates cooling rates of 100 to 1000 C/h, whereas olivine morphology indicates barred olivines cooled at rates of 250 to 1000 C/h. Texture/composition relationships suggest chondrules experienced initial temperatures below 1750 C. These observations are consistent with the idea that chondrules formed by transient heating in dust-rich regions (i.e., in the midplane) of the solar nebula.

Radomsky, Patrick M.↗
NASA NTRS1990

Temperature conditions for chondrule formation

An attempt is made to constrain the chondrule-forming process from dynamic crystallization experiments on chondrule analogs and from correlations between texture and bulk composition in natural chondrules. Liquidus temperatures for chondrules from unequilibrated chondrites are calculated using Herzberg's (1979) method. The paper then infers whether each chondrule formed above, at, or below its liquidus based on textures produced in experiments. A range of temperatures to which chondrules may have been initially heated is then derived from the texture-composition-temperature relationships. Finally, the role of dust seeding, or external heterogeneous nucleation, in producing chondrule textures is examined.

Hewins, Roger H.↗
NASA NTRS1990

High emittance surfaces for high temperature space radiator applications

Surface modification techniques are evaluated for emittance enhancement of radiator surfaces. These techniques include acid etching, heat treating, abrasion, sputter texturing, electrochemical texturing, arc texturing, and atomic oxygen beam texturing. Candidate radiator surface materials under consideration include Nb-1 pct Zr, Cu, Ti, Ti-6 pct Al-4 pct V, 304 stainless steel, Al6061-T6, Mo, W, and Ta.

Banks, Bruce A.↗