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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 1,207 records · Page 67

Method to measure orientation of discontinuous fiber embedded in the polymer matrix from computerized tomography scan data

Usage of discontinuous glass fibers in injection and compression molded resin components is rapidly increasing to improve their mechanical properties. Since added fiber contributes to more strength along the fiber direction compared to transverse direction, the mechanical properties of such components strongly depend on the fiber orientation. Thus it is important to estimate the fiber orientation distribution in such materials. Here, we are presenting recently developed method to estimate fiber orientation from 3D image of fibers generated using micro CT scan. Typically the 3D images from CT scan are very large and it becomes difficult to separate each fiber and extract end point information. In this paper a novel method to address this challenge is presented. The micro-CT images were broken into finite volume, reducing data size, and then each fiber was reduced to its own center line, further reducing the data size, using Mimics Innovation Suite (Materialise NV). These 3D centerlines were then used to quantify the 2nd order orientation tensor. Our results from the proposed method are compared with the measurements using well established industry standard approach called method of ellipses for validation. The key challenges in estimating the fiber orientation are identified and future improvements are proposed.

36 MATERIALS SCIENCE↗

Near-MHz temperature and H 2 O measurements in post-detonation fireballs of 25 g hemispherical explosives using scanned-wavelength-modulation spectroscopy

A laser absorption spectroscopy diagnostic integrated within a hardened optical probe was used to measure temperature and water mole fraction at 500 kHz in post-detonation fireballs of explosives. In the experiments, an exploding-bridgewire detonator initiated a 25 g hemisphere of explosive (N5 or PETN). This produced a hemispherical fireball that traveled radially towards a hardened measurement probe. The probe contained a pressure transducer and optical equipment to pitch fiber-coupled laser light across a 12.6 cm gap onto a detector. Tunable diode lasers emitting near 7185.6 and 6806 c m − <#comment/> 1 were used to measure the absorbance spectrum of H 2 O utilizing peak-picking scanned-wavelength-modulation spectroscopy with a scan frequency of 500 kHz and modulation frequencies of 35 and 45.5 MHz, respectively. This enabled measurements of temperature and X H 2 O in the shock-heated air and trailing fireball at 500 kHz. Time histories of pressure, temperature, and H 2 O mole fraction were acquired at different standoff distances to quantify how the fireball evolved in space and time as well as to compare measured quantities between PETN and N5 fireballs. The standard deviation of temperature and X H 2 O during one representative test were found to be 17 K (1.3%) and 0.011 (5%), respectively. These measurements demonstrate this diagnostic’s ability to provide rapid and reliable measurements in harsh, highly transient post-detonation environments produced by solid explosives.

Schwartz, Charles J.↗

Scanning holographic optical tweezers

The aim of this Letter is to introduce a new optical tweezers approach, called scanning holographic optical tweezers (SHOT), which drastically increases the working area (WA) of the holographic-optical tweezers (HOT) approach, while maintaining tightly focused laser traps. A 12-fold increase in the WA is demonstrated. The SHOT approach achieves its utility by combining the large WA of the scanning optical tweezers (SOT) approach with the flexibility of the HOT approach for simultaneously moving differently structured optical traps in and out of the focal plane. This Letter also demonstrates a new heuristic control algorithm for combining the functionality of the SOT and HOT approaches to efficiently allocate the available laser power among a large number of traps. The proposed approach shows promise for substantially increasing the number of particles that can be handled simultaneously, which would enable optical tweezers additive fabrication technologies to rapidly assemble microgranular materials and structures in reasonable build times.

42 ENGINEERING↗

The ABCs of phase retrieval: Connecting the acronyms of scanning transmission electron microscopy

High-resolution scanning transmission electron microscopy (S/TEM) is an indispensable tool for characterizing the structure and properties of materials down to the atomic scale. Conventional S/TEM imaging, however, is limited by the phase problem, whereby the phase of the electron exit wave is lost upon detection. Recent advances in diffractive imaging and 4D-STEM have enabled a range of phase-retrieval techniques that computationally reconstruct the missing information encoded in the phase of the transmission function. These approaches offer improved dose efficiency and enhanced sensitivity to weakly scattering signals, extending quantitative imaging to beam-sensitive materials composed of light elements. In this work, we introduce the phase problem in electron microscopy and survey the diverse landscape of phase-retrieval techniques used in the field. Despite their many acronyms and algorithmic variations, these techniques share a common physical and mathematical foundation. We present a unified framework that connects these seemingly distinct methods, from parallax imaging and tilt-corrected bright-field (tcBF-STEM), to aberration-corrected bright-field (acBF-STEM), optimum bright-field (OBF-STEM) and single-sideband (SSB) ptychography, as well as first-moment integrated center of mass techniques (iCOM) and iterative ptychographic algorithms. Based on these insights, we discuss the opportunities and practical limitations of applying these methods across different materials systems, detector designs, and microscope configurations.Graphical abstractRepresentative electron microscopy configurations used for phase retrieval and diffractive imaging in S/TEM: (a) Zernike phase-contrast transmission electron microscopy (TEM), (b) small-convergence-angle four-dimensional scanning transmission electron microscopy (4D-STEM) for nanobeam-based phase reconstruction methods, and (c) large-convergence-angle 4D-STEM for ptychographic and related diffractive imaging techniques reviewed in this work.

36 MATERIALS SCIENCE↗

Computed Tomography Scans of Naturally Mineralized Fractures in Upper Wolfcamp Shale

Computed tomography scans of fractures in small samples of Wolfcamp Shale from the Permian Basin and a depth of approximately 10,400 feet that have been cemented through natural processes. These samples were CT scanned at NETL. The data sets compliment the manuscript by Hajirezaie et al entitled "Mineral characterization of a sealed fracture: A multiscale multimodal imaging study of a syntaxial vein"

Computed Tomography↗

CT and Scanning Data of the KGS Wellington 1-32 CarbonSAFE Core

Data described in the NETL Technical Report Series "Computed Tomography Scanning and Geophysical Measurements of the Wellington 1-32 Core", including processed and raw CT and measurements from NETL's multi-sensor core logger. Paronish, T.; Schmitt, R.; Mitchell, N; Brown, S; Crandall, D.; Moore, J.; Hasiuk, F.; Potter, N.; Holubnyak, Y.E. Computed Tomography Scanning and Geophysical Measurements of the Wellington 1-32 Core; DOE.NETL-2021.2882; NETL Technical Report Series; U.S. Department of Energy, National Energy Technology Laboratory: Morgantown, WV, 2022; p 108. DOI: https://doi.org/10.2172/1894355 https://edx.netl.doe.gov/dataset/computed-tomography-scanning-and-geophysical-measurements-of-the-wellington-1-32-core

CarbonSafe↗

Evaluation of Anisotropic Magnetoresistive (AMR) Sensors for a Magnetic Field Scanning System for SRF Cavities

One of the significant causes of residual losses in superconducting radio-frequency (SRF) cavities is trapped magnetic flux. The flux trapping mechanism depends on many factors that include cool-down conditions, surface preparation techniques, and ambient magnetic field orientation. Suitable diagnostic tools are not yet available to quantitatively correlate such factors’ effect on the flux trapping mechanism. A magnetic field scanning system (MFSS) consisting of AMR sensors, fluxgate magnetometers, or Hall probes is recently commissioned to scan the local magnetic field of trapped vortices around 1.3 GHz single-cell SRF cavities. In this contribution, we will present results from sensitivity calibration and the first tests of AMR sensors in the MFSS.

Parajuli, I. P.↗

Case for an Improved Effective-Atomic-Number for the Electronic Baggage Scanning Program

Z eff , a parameter representing an 'effective atomic number' for a material, plays an important role in the Electronic Baggage Scanning Program (EBSP) to detect threats in dual-energy computed tomography (CT) baggage-scanning systems. We believe that Z eff , as defined and used on this program, does not provide the accurate representation of a material's x-ray absorption properties that is needed by the EBSP. We present the case for a new method that defines an effective atomic number for compounds and mixtures, which we refer to as Z e . Unlike Z eff , Z e is tied by definition to the x-ray absorption properties of each specific material. Use of this alternative will provide a more accurate scale for calibrating Micro-CT and EDS systems against standard reference materials and will provide a more accurate physical characterization of the x-ray properties of materials evaluated on those systems. This document: (1) Describes the current usage of the Z eff parameter; (2) Details problems entailed in the use of the Z eff parameter; (3) Proposes a well-defined alternative - Z e ; (4) Proposes and demonstrates an algorithm for optimally associating Z e with any specified compound or mixture; (5) Discusses issues that can impact the usefulness of an effective-Z model; and (6) Recommends that, in order that the chosen effective-Z parameter not materially impact the accuracy of data produced by the EBSP program, the use of Z eff be replaced by Z e .

42 ENGINEERING↗

X-band Scanning ARM Precipitation Radar (X-SAPR) Instrument Handbook

The X-band scanning ARM cloud radar (X-SAPR) is a full-hemispherical scanning polarimetric Doppler radar transmitting simultaneously in both H and V polarizations. With a 200 kW magnetron transmitter, this puts 100 kW of transmitted power for each polarization. The receiver for the X-SAPR is a Vaisala Sigmet RVP-900 operating in a coherent-on-receive mode. Three X-SAPRs are deployed around the Southern Great Plains (SGP) Central Facility in a triangular array. A fourth X-SAPR is deployed near Barrow, Alaska on top of the Barrow Arctic Research Center.

01 COAL, LIGNITE, AND PEAT↗

C-Band Scanning ARM Precipitation Radar (C-SAPR) Handbook

The C-band scanning ARM precipitation radar (C-SAPR) is a scanning polarimetric Doppler radar transmitting simultaneously in both H and V polarizations. With a 350-kW magnetron transmitter, this puts 125 kW of transmitted power for each polarization. The receiver for the C-SAPR is a National Center for Atmospheric Research (NCAR) -developed Hi-Q system operating in a coherent-on-receive mode. The ARM Climate Research Facility operates two C-SAPRs; one of them is deployed near the Southern Great Plains (SGP) Central Facility near the triangular array of X-SAPRs, and the second C-SAPR is deployed at ARM’s Tropical Western Pacific (TWP) site on Manus Island in Papua New Guinea.

47 OTHER INSTRUMENTATION↗

Measurements of transverse beam halo diffusion rates in the LHC with collimator scans

Measurements of beam halo dynamics were conducted in the LHC on 22 June 2012 at 4 TeV using collimator scans. Four scans were performed: on proton beam 1 with a vertical collimator and on beam 2 with a horizontal collimator, first with squeezed separated beams and subsequently in collision. The time evolution of losses following collimator steps provides experimental estimates of halo diffusion, halo population, impact parameter distributions, and beam jitter. Besides its general interest for beam dynamics and machine performance characterization, this information forms an essential input for the general design of collimation systems, including new methods such as crystal collimators and hollow electron lenses. In this note, the results of an analysis of the data is presented.

43 PARTICLE ACCELERATORS↗

Case for an Improved Effective-Atomic Number for the Electronic Baggage Scanning Program (Rev. 1)

Z eff , a parameter representing an “effective atomic number” for a material, plays an important role in the Electronic Baggage Scanning Program (EBSP) to detect threats in dual-energy computed tomography (CT) baggage-scanning systems. We believe that Zeff, as defined and used on this program, does not provide the most accurate representation of a material's x-ray properties.. We present the case for a new method that defines an effective atomic number for compounds and mixtures, which we refer to as Z e . Unlike Z eff , Z e is tied by definition to the x-ray absorption properties of each specific material. Use of this alternative will provide a more accurate scale for calibrating LLNL-designed Micro-CT systems and vendor-built Explosives Detection Systems (EDS) against standard reference materials, and it will provide a more accurate physical characterization of the x-ray properties of materials evaluated on those systems. This document, (1) Describes the current usage of the Z eff parameter; (2) Details problems entailed in the use of the Z eff parameter; (3) Proposes a well-defined alternative—Z e ; (4) Proposes and demonstrates an algorithm for optimally associating Z e with any specified compound or mixture; (5) Discusses issues that can impact the usefulness of an effective-Z model; and (6) Recommends that, in order that the chosen effective-Z parameter not materially impact the accuracy of data produced by the EBSP program, the use of Z eff be replaced by Z e .

42 ENGINEERING↗

Rapid Scan-Humidified Growth Cloud Condensation Nuclei Instrument

This research focused on enhancements to the streamwise thermal gradient cloud condensation nuclei counter to support the rapid scan mode and to enhance the capability for aerosol humidified growth measurements. The research identified the needs for flow system modifications and range of capability for operating the conventional instrument in the rapid scan and humidified growth modes.

47 OTHER INSTRUMENTATION↗

Increase scanning efficiency for bomb book ARIES documentation [Slides]

The improvement plan that was proposed in this yellow belt will significantly increase the number of pages scanned per minute from the bomb books. The improvement plan will also reduce the number of errors through the implementation of the new database created, also better quality from new scanner. This plan will significantly reduce the cost associated with the program by approximately $1.5 million over the duration of the program (~250K bomb books). However, more bomb books will ultimately be scanned. Continuous improvement opportunity: after installation of new equipment and changes to this process, recalculate with true (i.e., classified data) numbers for program manager briefing).

99 GENERAL AND MISCELLANEOUS↗

The oxidation of aluminum at high temperature studied by Thermogravimetric Analysis and Differential Scanning Calorimetry.

The oxidation in air of high-purity Al foil was studied as a function of temperature using Thermogravimetric Analysis with Differential Scanning Calorimetry (TGA/DSC). The rate and/or extent of oxidation was found to be a non-linear function of the temperature. Between 650 and 750 ÀC very little oxidation took place; at 850 ÀC oxidation occurred after an induction period, while at 950 ÀC oxidation occurred without an induction period. At oxidation temperatures between 1050 and 1150 ÀC rapid passivation of the surface of the aluminum foil occurred, while at 1250 ÀC and above, an initial rapid mass increase was observed, followed by a more gradual increase in mass. The initial rapid increase was accompanied by a significant exotherm. Cross-sections of oxidized specimens were characterized by scanning electron microscopy (SEM); the observed alumina skin thicknesses correlated qualitatively with the observed mass increases.

Coker, Eric Nicholas↗

Documentation and Instructions for Running Two Python Scripts that Aid in Setting up 3D Measurements using the Polytec 3D Scanning Laser Doppler Vibrometer

Sandia National Laboratories has recently purchased a Polytec 3D Scanning Laser Doppler Vibrometer for vibration measurement. This device has proven to be a very nice tool for making vibration measurements, and has a number of advantages over traditional sensors such as accelerometers. The non-contact nature of the laser vibrometer means there is no mass loading due to measuring the response. Additionally, the laser scanning heads can position the laser spot much more quickly and accurately than placing an accelerometer or performing a roving hammer impact. The disadvantage of the system is that a significant amount of time must be invested to align the lasers with each other and the part so that the laser spots can be accurately positioned. The Polytec software includes a number of nice tools to aid in this procedure; however, certain portions are still tedious. Luckily, the Polytec software is readily extensible by programming macros for the system, so tedious portions of the procedure can be made easier by automating the process. The Polytec Software includes a WinWrap (similar to Visual Basic) editor and interface to run macros written in that programming language. The author, however, is much more proficient in Python, and the latter also has a much larger set of libraries that can be used to create very complex macros, while taking advantage of Python’s inherent readability and maintainability.

47 OTHER INSTRUMENTATION↗

Development of Scanning Ultrafast Electron Microscope Capability.

Modern semiconductor devices rely on the transport of minority charge carriers. Direct examination of minority carrier lifetimes in real devices with nanometer-scale features requires a measurement method with simultaneously high spatial and temporal resolutions. Achieving nanometer spatial resolutions at sub-nanosecond temporal resolution is possible with pump-probe methods that utilize electrons as probes. Recently, a stroboscopic scanning electron microscope was developed at Caltech, and used to study carrier transport across a Si p-n junction [ 1 , 2 , 3 ] . In this report, we detail our development of a prototype scanning ultrafast electron microscope system at Sandia National Laboratories based on the original Caltech design. This effort represents Sandia's first exploration into ultrafast electron microscopy.

47 OTHER INSTRUMENTATION↗

Scanning Electron Microscopy (SEM) Procedure for HE Powders on a Zeiss Sigma HD VP SEM

This method describes the characterization of inert and HE materials by the Zeiss Sigma HD VP field emission Scanning Electron Microscope (SEM). The SEM uses an accelerated electron beam to generate high-magnification images of explosives and other materials. It is fitted with five detectors (SE, Inlens, STEM, VPSE, HDBSD) to enable imaging of the sample via different secondary electron signatures, angles, and energies. In addition to imaging through electron detection, the microscope is also fitted with two Oxford Instrument Energy Dispersive Spectrometer (EDS) 80 mm detectors to generate elemental constituent spectra and two-dimensional maps of the material being scanned.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗