Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “angle”

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 1,135 records · Page 63
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Investigation of the structure of unilamellar dimyristoylphosphatidylcholine vesicles in aqueous sucrose solutions by small-angle neutron and X-ray scattering

The structure of a polydispersed population of unilamellar dimyristoylphosphatidylcholine (DMPC) vesicles in sucrose solutions has been investigated by small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS). Calculations within the model of separated form factors (SFF) show that the structure of the vesicle system depends strongly on the sucrose concentration.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2016

Porosity and structural parameters of Karelian shungites according to the data of small-angle synchrotron radiation scattering and microscopy

The nanoporosity and structure of natural carbons has been investigated on the example of Karelian carbon-rich shungites by comparing the data of small-angle synchrotron radiation scattering and highresolution microscopy. The analysis of small-angle scattering data is based on the model of scattering spheres with lognormal size distribution. It is found that the structure of samples from the Maksovo and Zazhogino deposits subjected to high temperatures in the geological medium and (also to a lesser extent) a sample from the Shunga deposit can be described as an aggregation of polydisperse scattering spheres with lognormal size distribution; the characteristic scatterer size is determined for them. A comparison with microscopy data shows that these scatterers are mainly associated with pores, and the character of their size distribution is similar to that previously established for nanoglobules in schungites.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Microfluidic Cell for Studying the Precrystallization Stage Structure of Protein Solutions by Small-Angle X-Ray Scattering

A microfluidic cell has been developed for studying the structure of protein solutions using small-angle X-ray scattering. The use of prefabricated elements, which provide a small sample volume, allows one to adjust the microfluidic cell parameters to specific problems. Tests of lysozyme solutions were performed on a laboratory diffractometer AMUR-K (Institute of Crystallography, Russian Academy of Sciences), BM29 beamline (ESRF, Grenoble), and “DICSY” beamline of the Kurchatov synchrotron radiation source (National Research Centre “Kurchatov Institute”). Experiments showed that, when a 60-μm-thick quartz glass of special purity grade is applied as an X-ray-transparent window, the intrinsic level of cell background scattering in the range of measured angles is lower than that for quartz capillaries, due to which the measurement accuracy can be increased.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2020

Infrared Optical Constants from Pressed Pellets of Powders: I. Improved n and k Values of (NH4)(2)SO(4)from Single-Angle Reflectance

In combination with other parameters, the real, n(?), and imaginary, k(?), components of the complex refractive index, = n + ik, can be used to simulate the optical properties of a material in different forms, e.g. its infrared spectra. But obtaining reliable values of the optical constants n/k for solid materials is challenging due to the lack of optical quality specimens, usually crystals, large enough to measure. An alternative to crystals is to press the powder into a uniform disk. We have produced pellets from ammonium sulfate, (NH4)2SO4, powder and derived the pellets’ n and k values via single-angle reflectance using a specular reflectance device in combination with a Fourier transform infrared spectrometer. The single-angle technique measures amplitude of light reflected from the material as a function of wavelength over a wide spectral domain; the optical constants are determined from the reflectance data using the Kramers-Kronig relationship. We investigate several parameters associated with the pellets and pellet formation and their effects upon delivering the most reliable n/k values. Parameters studied include pellet diameter, mass and density (void space), drying, grinding, sieving and particle size in the pellet formation, as well as pressing pressure and duration. Of these parameters, using size-selected mixtures of dried, small (< 100 µm) particles and pressing at = 10 tons for at least 30 minutes were found key to forming highly reflective samples. Comparison to two sets of previous literature n(?) and k(?) values obtained from crystalline (NH4)2SO4 both as crystal reflectance as well as extinction spectra of aerosols measured in a flow tube show reasonable agreement, but suggests the present values, as confirmed from two independent techniques, represent a substantial improvement for n/k values for (NH4)2SO4, also demonstrating promise to measure the optical constants of other materials.

Optical constants, index of refraction, single-ang↗
DOE OSTI2016

Multi-Angle Snowflake Camera Value-Added Product

The Multi-Angle Snowflake Camera (MASC) addresses a need for high-resolution multi-angle imaging of hydrometeors in freefall with simultaneous measurement of fallspeed. As illustrated in Figure 1, the MASC consists of three cameras, separated by 36°, each pointing at an identical focal point approximately 10 cm away. Located immediately above each camera, a light aims directly at the center of depth of field for its corresponding camera. The focal point at which the cameras are aimed lies within a ring through which hydrometeors fall. The ring houses a system of near-infrared emitter-detector pairs, arranged in two arrays separated vertically by 32 mm. When hydrometeors pass through the lower array, they simultaneously trigger all cameras and lights. Fallspeed is calculated from the time it takes to traverse the distance between the upper and lower triggering arrays. The trigger electronics filter out ambient light fluctuations associated with varying sunlight and shadows. The microprocessor onboard the MASC controls the camera system and communicates with the personal computer (PC). The image data is sent via FireWire 800 line, and fallspeed (and camera control) is sent via a Universal Serial Bus (USB) line that relies on RS232-over-USB serial conversion. See Table 1 for specific details on the MASC located at the Oliktok Point Mobile Facility on the North Slope of Alaska. The value-added product (VAP) detailed in this documentation analyzes the raw data (Section 2.0) using Python: images rely on OpenCV image processing library and derived aggregated statistics rely on some clever averaging. See Sections 4.1 and 4.2 for more details on what variables are computed.

47 OTHER INSTRUMENTATION↗
DOE OSTI2022

Small-Angle Neutron Scattering for Studying Lipid Bilayer Membranes

Small-angle neutron scattering (SANS) is a powerful tool for studying biological membranes and model lipid bilayer membranes. The length scales probed by SANS, being from 1 nm to over 100 nm, are well-matched to the relevant length scales of the bilayer, particularly when it is in the form of a vesicle. However, it is the ability of SANS to differentiate between isotopes of hydrogen as well as the availability of deuterium labeled lipids that truly enable SANS to reveal details of membranes that are not accessible with the use of other techniques, such as small-angle X-ray scattering. In this work, an overview of the use of SANS for studying unilamellar lipid bilayer vesicles is presented. The technique is briefly presented, and the power of selective deuteration and contrast variation methods is discussed. Approaches to modeling SANS data from unilamellar lipid bilayer vesicles are presented. Finally, recent examples are discussed. While the emphasis is on studies of unilamellar vesicles, examples of the use of SANS to study intact cells are also presented.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS1991

Use of piloted simulation for high-angle-of-attack agility research and design criteria development

This paper reviews the use of piloted simulation at Langley Research Center as part of the NASA High-Angle-of-Attack Technology Program (HAATP) program to provide methods and concepts for the design of advanced fighter aircraft. A major focus of this program is to develop the design process required to fully exploit the benefits from advanced control concept for high-angle-of-attack agility. Important methodologies associated with the effective us of piloted simulation of the research are described, particularly those relating to the test techniques, validation of the test results, and design guidelines/criteria development.

Angle of attack↗
NASA NTRS1946

Tank tests to determine the effect of varying design parameters of planing-tail hulls II : effect of varying depth of step, angle of after- body keel, length of afterbody chine, and gross load

The second part of a series of tests made in Langley tank no. 2 to determine the effect of varying design parameters of planing-tail hulls is presented. Results are given to show the effects on resistance characteristics of varying angle of afterbody keel, depth of step, and length of afterbody chine. The effect of varying the gross load is shown for one configuration. The resistance characteristics of planing-tail hulls are compared with those of a conventional flying-boat hull. The forces on the forebody and afterbody of one configuration are compared with the forces on a conventional hull. Increasing the angle of afterbody keel had small effect on hump resistance and no effect on high-speed resistance but increased free-to-trim resistance at intermediate speeds. Increasing the depth of step increased hump resistance, had little effect on high-speed resistance, and increased free-to-trim resistance at intermediate speeds. Omitting the chines on the forward 25 percent of the afterbody had no appreciable effect on resistance. Omitting 70 percent of the chine length had almost no effect on maximum resistance but broadened the hump and increased spray around the afterbody. Load-resistance ratio at the hump decreased more rapidly with increasing load coefficient for the planing-tail hull than for the representative conventional hull, although the load-resistance ratio at the hump was greater for the planing-tail hull than for the conventional hull throughout the range of loads tested. At speeds higher than hump speed, load-resistance ratio for the planing-tail hull was a maximum at a particular gross load and was slightly less at heavier and lighter gross loads. The planing-tail hull was found to have lower resistance than the conventional hull at both the hump and at high speeds, but at intermediate speeds there was little difference. The lower hump resistance of the planing-tail hull was attributed to the ability of the afterbody to carry a greater percentage of the total load while maintaining a higher value of load-resistance ratio.

HULLS - RESISTANCE - TANK TESTS (NACA-#2)↗
NASA NTRS1922

Effect of periodic changes of angle of attack on behavior of airfoils

This report presents the results of a series of experiments, which gave some quantitative results on the effect of periodic changes in the direction of the relative air flow against airfoils. The first series of experiments concerned how the angle of attack of the wing model was changed by causing the latter to oscillate about an axis parallel to the span and at right angles to the air flow. The second series embraced all the experiments in which the direction of the air flow itself was periodically changed.

AIRFOILS - ANGLE OF ATTACK↗
NASA NTRS1995

Sensitivity of Multi-Angle Remote Sensing Observations to Aerosol Sphericity

Multi-angle, multi-spectral remote sensing observations, such as those anticipated from the Earth Observing System (EOS) Multi-angle Imaging SpectroRadiometer (MISR), can distinguish spherical from non-spherical particles over calm ocean for mineral-dust-like particles with the range of sizes and column amounts expected under natural conditions. The ability to make such distinctions is critical if remote sensing of atmospheric aerosol properties is to provide significant new contributions to our understanding of the global-scale, clear-sky solar radiation balance.

MISR aerosol aerosol properties↗
NASA NTRS1993

The Coherent Backscattering Opposition Effect: Measurements at Very Small Phase Angles

This oral presentation explains that measurements of the opposition surge (the nonlinear increase in reflectance seen in particulate materials when observed at small phase angles) are the first ever made using the JPL long-arm goniometer, which permits very small phase angle measuremnets to be made.

long-arm goniometer phase angles coherent backscat↗
NASA NTRS1995

Second Order Angle of Incidence Corrections for GaAs /Ge Solar cells with Low Absorptance Coverglass

The objective of this paper was to determine any angle of incidence effects beyond the cosine and Fresnel reflection corrections. Two samples each of several GaAs /Ge cell assemblies were measured at incidence angles from 0 to 85o to provide a survey for possible second order corrections that would have to be applied to solar arrays with non-normal incident light.

angle of incidence effects↗
NASA NTRS2003

MISR Multi-Angle Imaging SpectroRadiometer

This viewgraph presentation reviews the concept of the Multi-Angle Imaging SpectroRadiometer (MISR), a methodology to use the MISR to retrieve aerosols over water and land. The presentation shows some of the results of the use of the MISR in graphs and charts. Multi-angle remote sensing provides unique ways of retrieving aerosol properties over many surface types, including bright deserts which are major source regions.

global maps↗
NASA NTRS2014

Geostationary Coastal and Air Pollution Events (GeoCAPE) Wide Angle Spectrometer (WAS)

The GeoCAPE Wide Angle Spectrometer (WAS) Study was a revisit of the COEDI Study from 2012. The customer primary goals were to keep mass, volume and cost to a minimum while meeting the science objectives and maximizing flight opportunities by fitting on the largest number of GEO accommodations possible. Riding on a commercial GEO satellite minimizes total mission costs. For this study, it is desired to increase the coverage rate,km2min, while maintaining ground sample size, 375m, and spectral resolution, 0.4-0.5nm native resolution. To be able to do this, the IFOV was significantly increased, hence the wide angle moniker. The field of view for COEDI was +0.6 degrees or (2048) 375m ground pixels. The WAS Threshold (the IDL study baseline design) is +2.4 degrees IDL study baseline design) is +2.4 degrees.

pointing and jitter↗
DOE OSTI2016

Small-Angle Neutron Scattering Measurements of the δ Deuteride Phase in Zircaloy 4

Hydrogen pickup by Zr-based LWR fuel cladding during service leads to the formation of circumferential hydride platelet particles embedded within the Zr matrix. The precipitation of the hydride phase occurs preferentially on the water-side due to the temperature gradient within the clad wall. The non-uniform hydride morphology is known as a rim structure. Significant tensile hoop stresses within the clad wall develop during the fuel lifetime due to fission gas release and pellet-clad mechanical interaction. One potential post-service cladding failure mechanism is delayed hydride cracking (DHC) initiated by hydride reorientation under this tensile hoop stress. As a consequence, hydride reorientation and DHC have been extensively studied over the last few decades to understand the interdependencies of tensile stress, temperature, hydride morphology, and hydrogen concentration. Much of the most recent work in this area has taken advantage of 3. generation synchrotron X-ray sources to perform in situ measurements of hydride phase stability. Neutron scattering based techniques offer unique advantages in the study of hydrogen in metals (typically with deuterium substituted for hydrogen) but are under utilized in the study of hydrides in Zr. We present small-angle neutron scattering (SANS) measurements of the deuteride phase in Zircaloy 4 (Zy4) here. The SANS measurements presented here demonstrate the sensitivity of the technique to deuteride phase particles embedded in a Zy4 matrix. Quantifiable net scattering at 50 wppm effective hydrogen concentration is derived from a subtraction of a reference sample. This demonstrates that the strong χ phase Porod scattering can be effectively eliminated, revealing the response from the deuteride phase. A similar experimental protocol using small-angle X-ray scattering (SAXS) would likely fail due to poor contrast between the hydride phase and the Zr matrix. Stated in different terms, the SAXS response would be dominated by SPP Porod scattering with unresolvable net scattering from hydride particles. (authors)

36 MATERIALS SCIENCE↗
DOE OSTI2017

On the origin of low-energy electrons in the inner magnetosphere: Fluxes and pitch-angle distributions

Correct knowledge of the plasma fluxes in the inner magnetosphere is crucial for both scientific and programmatic applications. Knowledge of the low-energy electrons (approximately tens to hundreds of eV) in the inner magnetosphere is particularly important since these electrons are acted upon by various physical processes, accelerating the electrons to higher energies, and also causing their loss. However, measurements of low-energy electrons are challenging, and as a result, this population has been somewhat neglected previously. This work concerns observations of low-energy electrons made by the Helium Oxygen Proton Electron instrument on board the Van Allen Probes satellites and also observations from geosynchronous orbit made by the Magnetospheric Plasma Analyzer on board Los Alamos National Laboratory satellites. The fluxes of electrons from ~30 eV to 1 keV are quantified as a function of pitch-angle, McIlwain L parameter, and local time for both quiet and active periods. Results indicate two sources for low-energy electrons in this energy range: the low-energy tail of the electron plasma sheet and the high-energy tail of the dayside ionosphere. These populations are identified primarily as a result of their different pitch-angle distributions. Field-aligned outflows from the dayside ionosphere are observed at all L shells during quiet and active periods. Our findings also demonstrate that the dayside electron field-aligned fluxes at ~30 eV are particularly strong between L values of 6 and 7, indicating an enhanced source within the polar ionosphere.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗