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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 613 records · Page 34
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Three-dimensional hierarchical nanoporous copper via direct ink writing and dealloying

Three-dimensional (3D) hierarchical nanoporous Cu (3DHNP-Cu) is synthesized using a combination of direct ink writing (DIW) based 3D printing, thermal sintering, and chemical dealloying of Mn–Cu alloys. Through tuning processing conditions such as ink composition and cooling rate (after sintering), with consideration of Mn loss during sintering, 3DHNP-Cu with fully bicontinuous nanostructures and negligible residual Mn can be produced after dealloying. The 3DHNP-Cu is comprised of structural features that span seven orders of magnitude, where DIW digitally controls macroscale porous features, thermal sintering and degradation of the binding polymer determines microscale porous features, and dealloying gives rise to nanoscale pores.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Object-space optimization of tomographic reconstructions for additive manufacturing

Volumetric 3D printing motivated by computed axial lithography enables rapid printing of homogeneous parts but requires a high dimensionality gradient-descent optimization to calculate image sets. Here we introduce a new, simpler approach to image-computation that algebraically optimizes a model of the printed object, significantly improving print accuracy of complex parts under imperfect material and optical precision by improving optical dose contrast between the target and surrounding regions. Quality metrics for volumetric printing are defined and shown to be significantly improved by the new algorithm. The approach is extended beyond binary printing to grayscale control of conversion to enable functionally graded materials. The flexibility of the technique is digitally demonstrated with realistic projector point spread functions, printing around occluding structures, printing with restricted angular range, and incorporation of materials chemistry such as inhibition. Finally, simulations show that the method facilitates new printing modalities such as printing into flat, rather than cylindrical packages to extend the applications of volumetric printing.

36 MATERIALS SCIENCE↗
NASA NTRSDate not supplied

Advances in Integrally Formed Metallic Structures

NASA Langley Research Center (LaRC) is applying flow forming technology to aerospace aluminum alloys for the manufacture of integrally stiffened cylinders that meet aircraft fuselage or launch vehicle specifications. High-strength 2xxx series alloys, in various temper/product form conditions, are being compared with medium-strength, very formable AA 6061 as the benchmark. Screening of candidate materials traditionally relies on empirical forming trials, but more recently on metrics derived from constant nominal strain rate tensile testing. In this work, the established hierarchy of formability metrics is adopted as the baseline; tensile area reduction, work hardening exponent, and modulus of resilience. The suite of metrics can be expanded based on phenomenological and mechanistic considerations of plastic flow instabilities to incorporate anisotropy ratio, rate of work hardening, and dynamic strain aging effects. Separate research thrusts at LaRC are aimed at formulating a protocol for scalable production of fully formed, defect-free components: 1) quantifying the extended set of formability metrics from constant and jump strain rate tensile tests with digital image correlation (DIC); 2) using statistically designed experiments on a vertical spin/flow forming facility (WF VUD-600®) to isolate the effect of convenient process variables, such as axial feed rate and thickness reduction; and 3) predicting the effect of feed ratio (roller translation relative to mandrel rotation speeds) on material response via process modeling using the DEFORM® simulation software. Current results will be discussed in terms of correlating intrinsic material properties with the bulk workability characteristics to successfully fabricate cylinders with complex cross-sections.

Aluminum↗
DOE OSTI2022

Characterizing the Thermal-Induced Distortion of Large-Scale Polymer Composite Printed Structures

The Big Area Additive Manufacturing (BAAM) system has been used to print large-scale parts, such as automotive structures and molds for tooling, with fiber-reinforced polymer composites. Incorporating reinforcing fibers in printed parts is commonly used to increase stiffness and strength, but it also introduces significant anisotropy in the thermomechanical performance, which can lead to distortion and warping during thermal cycling. Characterizing and understanding how a printed tool distorts is crucial to maintaining tolerances and avoiding part failure. This study uses digital image correlation (DIC) to measure the coefficient of thermal expansion (CTE) of a printed part from room temperature and to a known steady state temperature. The samples were printed with carbon fiber reinforced acrylonitrile butadiene styrene (CF-ABS). Various nozzle geometries were evaluated in this study with the intent of minimizing the thermal- induced distortion experienced by printed parts.

Corum, Tyler↗
DOE OSTI2015

TU-F-201-00: Radiochromic Film Dosimetry Update

Since the introduction of radiochromic films (RCF) for radiation dosimetry, the scope of RCF dosimetry has expanded steadily to include many medical applications, such as radiation therapy and diagnostic radiology. The AAPM Task Group (TG) 55 published a report on the recommendations for RCF dosimetry in 1998. As the technology is advancing rapidly, and its routine clinical use is expanding, TG 235 has been formed to provide an update to TG-55 on radiochromic film dosimetry. RCF dosimetry applications in clinical radiotherapy have become even more widespread, expanding from primarily brachytherapy and radiosurgery applications, and gravitating towards (but not limited to) external beam therapy (photon, electron and protons), such as quality assurance for IMRT, VMAT, Tomotherapy, SRS/SRT, and SBRT. In addition, RCF applications now extend to measurements of radiation dose in particle beams and patients undergoing medical exams, especially fluoroscopically guided interventional procedures and CT. The densitometers/scanners used for RCF dosimetry have also evolved from the He-Ne laser scanner to CCD-based scanners, including roller-based scanner, light box-based digital camera, and flatbed color scanner. More recently, multichannel RCF dosimetry introduced a new paradigm for external beam dose QA for its high accuracy and efficiency. This course covers in detail the recent advancements in RCF dosimetry. Learning Objectives: Introduce the paradigm shift on multichannel film dosimetry Outline the procedures to achieve accurate dosimetry with a RCF dosimetry system Provide comprehensive guidelines on RCF dosimetry for various clinical applications One of the speakers has a research agreement from Ashland Inc., the manufacturer of Gafchromic film.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

TU-F-201-01: General Aspects of Radiochromic Film Dosimetry

Since the introduction of radiochromic films (RCF) for radiation dosimetry, the scope of RCF dosimetry has expanded steadily to include many medical applications, such as radiation therapy and diagnostic radiology. The AAPM Task Group (TG) 55 published a report on the recommendations for RCF dosimetry in 1998. As the technology is advancing rapidly, and its routine clinical use is expanding, TG 235 has been formed to provide an update to TG-55 on radiochromic film dosimetry. RCF dosimetry applications in clinical radiotherapy have become even more widespread, expanding from primarily brachytherapy and radiosurgery applications, and gravitating towards (but not limited to) external beam therapy (photon, electron and protons), such as quality assurance for IMRT, VMAT, Tomotherapy, SRS/SRT, and SBRT. In addition, RCF applications now extend to measurements of radiation dose in particle beams and patients undergoing medical exams, especially fluoroscopically guided interventional procedures and CT. The densitometers/scanners used for RCF dosimetry have also evolved from the He-Ne laser scanner to CCD-based scanners, including roller-based scanner, light box-based digital camera, and flatbed color scanner. More recently, multichannel RCF dosimetry introduced a new paradigm for external beam dose QA for its high accuracy and efficiency. This course covers in detail the recent advancements in RCF dosimetry. Learning Objectives: Introduce the paradigm shift on multichannel film dosimetry Outline the procedures to achieve accurate dosimetry with a RCF dosimetry system Provide comprehensive guidelines on RCF dosimetry for various clinical applications One of the speakers has a research agreement from Ashland Inc., the manufacturer of Gafchromic film.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

TU-F-201-02: Applications in SRS, SBRT, IMRT, VMAT, and KV Imaging

Since the introduction of radiochromic films (RCF) for radiation dosimetry, the scope of RCF dosimetry has expanded steadily to include many medical applications, such as radiation therapy and diagnostic radiology. The AAPM Task Group (TG) 55 published a report on the recommendations for RCF dosimetry in 1998. As the technology is advancing rapidly, and its routine clinical use is expanding, TG 235 has been formed to provide an update to TG-55 on radiochromic film dosimetry. RCF dosimetry applications in clinical radiotherapy have become even more widespread, expanding from primarily brachytherapy and radiosurgery applications, and gravitating towards (but not limited to) external beam therapy (photon, electron and protons), such as quality assurance for IMRT, VMAT, Tomotherapy, SRS/SRT, and SBRT. In addition, RCF applications now extend to measurements of radiation dose in particle beams and patients undergoing medical exams, especially fluoroscopically guided interventional procedures and CT. The densitometers/scanners used for RCF dosimetry have also evolved from the He-Ne laser scanner to CCD-based scanners, including roller-based scanner, light box-based digital camera, and flatbed color scanner. More recently, multichannel RCF dosimetry introduced a new paradigm for external beam dose QA for its high accuracy and efficiency. This course covers in detail the recent advancements in RCF dosimetry. Learning Objectives: Introduce the paradigm shift on multichannel film dosimetry Outline the procedures to achieve accurate dosimetry with a RCF dosimetry system Provide comprehensive guidelines on RCF dosimetry for various clinical applications One of the speakers has a research agreement from Ashland Inc., the manufacturer of Gafchromic film.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

TU-F-201-03: Applications in Brachytherapy

Since the introduction of radiochromic films (RCF) for radiation dosimetry, the scope of RCF dosimetry has expanded steadily to include many medical applications, such as radiation therapy and diagnostic radiology. The AAPM Task Group (TG) 55 published a report on the recommendations for RCF dosimetry in 1998. As the technology is advancing rapidly, and its routine clinical use is expanding, TG 235 has been formed to provide an update to TG-55 on radiochromic film dosimetry. RCF dosimetry applications in clinical radiotherapy have become even more widespread, expanding from primarily brachytherapy and radiosurgery applications, and gravitating towards (but not limited to) external beam therapy (photon, electron and protons), such as quality assurance for IMRT, VMAT, Tomotherapy, SRS/SRT, and SBRT. In addition, RCF applications now extend to measurements of radiation dose in particle beams and patients undergoing medical exams, especially fluoroscopically guided interventional procedures and CT. The densitometers/scanners used for RCF dosimetry have also evolved from the He-Ne laser scanner to CCD-based scanners, including roller-based scanner, light box-based digital camera, and flatbed color scanner. More recently, multichannel RCF dosimetry introduced a new paradigm for external beam dose QA for its high accuracy and efficiency. This course covers in detail the recent advancements in RCF dosimetry. Learning Objectives: Introduce the paradigm shift on multichannel film dosimetry Outline the procedures to achieve accurate dosimetry with a RCF dosimetry system Provide comprehensive guidelines on RCF dosimetry for various clinical applications One of the speakers has a research agreement from Ashland Inc., the manufacturer of Gafchromic film.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

TU-F-201-04: Applications in Small Fields and Proton Beams

Since the introduction of radiochromic films (RCF) for radiation dosimetry, the scope of RCF dosimetry has expanded steadily to include many medical applications, such as radiation therapy and diagnostic radiology. The AAPM Task Group (TG) 55 published a report on the recommendations for RCF dosimetry in 1998. As the technology is advancing rapidly, and its routine clinical use is expanding, TG 235 has been formed to provide an update to TG-55 on radiochromic film dosimetry. RCF dosimetry applications in clinical radiotherapy have become even more widespread, expanding from primarily brachytherapy and radiosurgery applications, and gravitating towards (but not limited to) external beam therapy (photon, electron and protons), such as quality assurance for IMRT, VMAT, Tomotherapy, SRS/SRT, and SBRT. In addition, RCF applications now extend to measurements of radiation dose in particle beams and patients undergoing medical exams, especially fluoroscopically guided interventional procedures and CT. The densitometers/scanners used for RCF dosimetry have also evolved from the He-Ne laser scanner to CCD-based scanners, including roller-based scanner, light box-based digital camera, and flatbed color scanner. More recently, multichannel RCF dosimetry introduced a new paradigm for external beam dose QA for its high accuracy and efficiency. This course covers in detail the recent advancements in RCF dosimetry. Learning Objectives: Introduce the paradigm shift on multichannel film dosimetry Outline the procedures to achieve accurate dosimetry with a RCF dosimetry system Provide comprehensive guidelines on RCF dosimetry for various clinical applications One of the speakers has a research agreement from Ashland Inc., the manufacturer of Gafchromic film.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2026

Powder metallurgy hot isostatic pressing - workshop report

The findings of the powder metallurgy (PM) hot isostatic pressing (HIP) workshop confirmed that the accelerated adoption of this technology requires the following action items: 1. By 2035, the HIP infrastructure must be scaled to sizes larger than 4 .0 meters for manufacturing components relevant to energy and defense industries at large. 2. The community must develop cost-effective and agile standards, qualifications, and certification pathways for these HIP parts. 3. At the same time, domestic powder production should be expanded to a wide range of metallic alloys, including Cr-Mo steels, stainless steels, and titanium- and nickel-based superalloys, as well as to emerging alloy classes in the refractory space. 4. The above initiatives can be enhanced by implementing digital modeling and controls, including AI-driven simulations, in situ monitoring, and digital twins.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Impact of Linearity and Write Noise of Analog Resistive Memory Devices in a Neural Algorithm Accelerator

Resistive memory (ReRAM) shows promise for use as an analog synapse element in energy-efficient neural network algorithm accelerators. A particularly important application is the training of neural networks, as this is the most computationally-intensive procedure in using a neural algorithm. However, training a network with analog ReRAM synapses can significantly reduce the accuracy at the algorithm level. In order to assess this degradation, analog properties of ReRAM devices were measured and hand-written digit recognition accuracy was modeled for the training using backpropagation. Bipolar filamentary devices utilizing three material systems were measured and compared: one oxygen vacancy system, Ta-TaO x , and two conducting metallization systems, Cu-SiO 2 , and Ag/chalcogenide. Analog properties and conductance ranges of the devices are optimized by measuring the response to varying voltage pulse characteristics. Key analog device properties which degrade the accuracy are update linearity and write noise. Write noise may improve as a function of device manufacturing maturity, but write nonlinearity appears relatively consistent among the different device material systems and is found to be the most significant factor affecting accuracy. As a result, this suggests that new materials and/or fundamentally different resistive switching mechanisms may be required to improve device linearity and achieve higher algorithm training accuracy.

97 MATHEMATICS AND COMPUTING↗
NASA NTRS2014

Experimental Evaluation of Fatigue Damage Progression in Postbuckled Single Stringer Composite Specimens

The durability and damage tolerance of postbuckled composite structures are not yet completely understood, and remain difficult to predict due to the nonlinearity of the geometric response and its interaction with local damage modes. A research effort was conducted to investigate experimentally the quasi-static and fatigue damage progression in a single-stringer compression (SSC) specimen. Three specimens were manufactured with a hat-stiffener, and an initial defect was introduced with a Teflon film embedded between one flange of the stringer and the skin. One of the specimens was tested under quasi-static compressive loading, while the remaining two specimens were tested by cycling in postbuckling. The tests were performed at the NASA Langley Research Center under controlled conditions and with instrumentation that allows a precise evaluation of the postbuckling response and of the damage modes. Three-dimensional digital image correlation VIC-3D systems were used to provide full field displacements and strains on the skin and the stringer. Passive thermal monitoring was conducted during the fatigue tests using an infrared camera that showed the location of the delamination front while the specimen was being cycled. The live information from the thermography was used to stop the fatigue tests at critical stages of the damage evolution to allow detailed ultrasonic scans.

Bisagni, Chiara↗
DOE OSTI2023

Wafer-Scale Synthesis of 2D Materials by an Amorphous Phase-Mediated Crystallization Approach

The interest in the wafer-scale growth of two-dimensional (2D) materials, including transition metal dichalcogenides (TMDCs), has been rising for transitioning from lab-scale devices to commercial-scale systems. Among various synthesis techniques, physical vapor deposition, such as pulsed laser deposition (PLD), has shown promise for the wafer-scale growth of 2D materials. However, due to the high volatility of chalcogen atoms (e.g., S and Se), films deposited by PLD usually suffer from a lack of stoichiometry and chalcogen deficiency. To mitigate this issue, excess chalcogen is necessary during the deposition, which results in problems like uniformity or not being repeatable. This study demonstrates a condensed-phase or amorphous phase-mediated crystallization (APMC) approach for the wafer-scale synthesis of 2D materials. This method uses a room-temperature PLD process for the deposition and formation of amorphous precursors with controlled thicknesses, followed by a post-deposition crystallization process to convert the amorphous materials to crystalline structures. This approach maintains the stoichiometry of the deposited materials throughout the deposition and crystallization process and enables the large-scale synthesis of crystalline 2D materials (e.g., MoS 2 and WSe 2 ) on Si/SiO 2 substrates, which is critical for future wafer-scale electronics. We show that the thickness of the layers can be digitally controlled by the number of laser pulses during the PLD phase. Optical spectroscopy is used to monitor the crystallization dynamics of amorphous layers as a function of annealing temperature. The crystalline quality, domain sizes, and the number of layers were explored using nanoscale and atomistic characterization (e.g., AFM, STEM, and EDS) along with electrical characterization to explore process–structure–performance relationships. Finally, this growth technique is a promising method that could potentially be adopted in conventional semiconductor industries for wafer-scale manufacturing of next-generation electronic and optoelectronic devices.

2D electronics↗
DOE OSTI2016

Arduino based radiation survey meter

This paper presents the design of new digital radiation survey meter with LND7121 Geiger Muller tube detector and Atmega328P microcontroller. Development of the survey meter prototype is carried out on Arduino Uno platform. 16-bit Timer1 on the microcontroller is utilized as external pulse counter to produce count per second or CPS measurement. Conversion from CPS to dose rate technique is also performed by Arduino to display results in micro Sievert per hour (μSvhr{sup −1}). Conversion factor (CF) value for conversion of CPM to μSvhr{sup −1} determined from manufacturer data sheet is compared with CF obtained from calibration procedure. The survey meter measurement results are found to be linear for dose rates below 3500 µSv/hr.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS1973

Computer program to perform cost and weight analysis of transport aircraft. Volume 1: Summary

A digital computer program for evaluating the weight and costs of advanced transport designs was developed. The resultant program, intended for use at the preliminary design level, incorporates both batch mode and interactive graphics run capability. The basis of the weight and cost estimation method developed is a unique way of predicting the physical design of each detail part of a vehicle structure at a time when only configuration concept drawings are available. In addition, the technique relies on methods to predict the precise manufacturing processes and the associated material required to produce each detail part. Weight data are generated in four areas of the program. Overall vehicle system weights are derived on a statistical basis as part of the vehicle sizing process. Theoretical weights, actual weights, and the weight of the raw material to be purchased are derived as part of the structural synthesis and part definition processes based on the computed part geometry.

Source record↗
NASA NTRS1993

The modern high rate digital cassette recorder

The magnetic tape recorder has played an essential role in the capture and storage of instrumentation data for more than thirty years. During this time, data recording technology has steadily progressed to meet user demands for more channels, wider bandwidths, and longer recording durations. When acquisition and processing moved from analog to digital techniques, so recorder design followed suit. Milestones marking the evolution of the data recorder through these various stages - multi-track analog, high density longitudinal digital, and more recently rotary digital - have often represented important breakthroughs in the handling of ever-greater quantities of data. Throughout this period there has been a very clear line of demarcation between data storage methods in the 'instrumentation world' on the one hand and the 'computer peripheral world' on the other. This is despite the fact that instrumentation data, whether analog or digital at the point of acquisition, is now likely to be processed on a digital computer at some stage. Regardless of whether the processing device is a small personal computer, a workstation, or the largest supercomputer, system integrators have traditionally been faced with the same basic problem - how to interface what is essentially a manually controlled, continuously running device (the tape recorder) into the fast start/stop computer environment without resorting to an excessive amount of complex custom interfacing and performance compromise. The increasing availability of affordable high power processing equipment throughout the scientific world is forcing recorder manufacturers to make their latest and perhaps most important breakthrough - the computer-friendly data recorder. The operating characteristics of such recorders are discussed and the resultant impact on both data acquisition and data analysis elements of system configuration are considered.

Clemow, Martin↗
NASA NTRS1995

IMS R and D program at Canada customs

Over the last few years, Revenue Canada, in collaboration with Barringer Instruments Limited, has been involved in the development of a field-usable ion mobility spectrometer (IMS) for the detection of drugs of abuse. This work has culminated in the manufacturing and commercialization by Barringer of the Ionscan 350 instruments, now in use by various law enforcement agencies worldwide. Although IMS exhibits a very strong and distinctive response toward some nitrogen containing drugs, e.g., cocaine, like all separation techniques it has inherent limitations, namely moderate resolution and low chemical signal to noise ratio which may affect the reliability of IMS-based drug detectors. A program is in place at the Laboratory and Scientific Services Directorate (LSSD) to investigate the applicability of various digital signal processing (DSP) techniques to IMS output signals. The application of neural network techniques to overlapping IMS peaks is presented.

Pilon, Pierre↗
DOE OSTI2020

Neural Learning Based Blind Source Separation for Detection of Material Defects in Pulsed Thermography Images

In this paper, we introduce a neural learning-based approach to blind source separation for detection of material flaws in pulsed thermography (PT) images. This approach can be used to detect internal defects (pores) in metallic Additively Manufactured (AM) materials. Such defects occur in high-strength alloys produced with direct laser sintering AM method for nuclear energy applications. Pulsed thermal imaging system utilizes a high intensity flash lamp to rapidly heat surface of sample, a high sensitivity infrared camera to capture data of surface temperature variations. The data cube obtained with PT (stack of surface temperature images at different times) can be analyzed with image processing algorithms to detect material defects. Compared with conventional nondestructive evaluation (NDE) methods, such as digital radiography and ultrasonic testing, the PT pulsed infrared thermal detection technique has advantages of one-sided non-contact measurements, fast processing of large sample areas captured in one image. Detection of small material defects requires finding features in thermal images, which have signal contrast levels approaching sensitivity limit of IR camera. In this study, an optimized Neural Learning based Blind Source Separation (NLBSS) algorithm, including Principal Component Analysis (PCA), and Independent Component Analysis (ICA) is demonstrated to automatically extract principal temporal and spatial features of thermography frames to enhance flaw detection. By using the NLBSS algorithm, material internal defects can be automatically detected. Furthermore, this processing approach compensates for experimental thermal imaging artifacts, such as noise and uneven heating. By merging artificial intelligence with the photothermic, the NDE system detects internal calibrated defects of various sizes and depths in AM nuclear-grade metallic alloys.

Zhang, Xin↗