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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Driving macro-scale transformations in three-dimensional-printed biopolymers through controlled induction of molecular anisotropy at the nanoscale

Motivated by the need to harness the properties of renewable and biodegradable polymers for the design and manufacturing of multi-scale structures with complex geometries, we have employed our additive manufacturing platform that leverages molecular self-assembly for the production of metre-scale structures characterized by complex geometries and heterogeneous material composition. As a precursor material, we used chitosan, a chemically modified form of chitin, an abundant and sustainable structural polysaccharide. We demonstrate the ability to control concentration-dependent crystallization as well as the induction of the preferred orientation of the polymer chains through the combination of extrusion-based robotic fabrication and directional toolpathing. Anisotropy is demonstrated and assessed through high-resolution micro-X-ray diffraction in conjunction with finite element simulations. Using this approach, we can leverage controlled and user-defined small-scale propagation of residual stresses to induce large-scale folding of the resulting structures.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Results of Long-Term Analyses of the Salt (Macro) Batch 11 Tank 21H Qualification Sample

Savannah River National Laboratory (SRNL) analyzed samples from Tank 21H in support of qualification of Salt Waste Processing Facility (SWPF) Salt Batch 11. This document reports the long-term results of the analyses of the sample of Tank 21H. Analysis of this sample indicates that the material does not display any unusual characteristics or observations, such as visually apparent solids. However, the sample was dark colored. This report satisfies Deliverable 3 of the Technical Task Request (TTR). This revision adds a further triplicate analysis for 129 I content.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2024

Results of Long-Term Analyses of the Salt (Macro) Batch 13 Tank 42H Qualification Sample

Savannah River National Laboratory (SRNL) analyzed samples from Tank 42H in support of qualification of Salt Waste Processing Facility (SWPF) Salt Batch 13. This document reports the long-term results of the analyses of the sample of Tank 42H. Analysis of this sample indicates that the material does not display any unusual characteristics or observations, such as visually apparent solids. This report satisfies Deliverable 3 of the Technical Task Request (TTR).

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2025

Results of Long-Term Analyses of the Salt (Macro) Batch 14 Tank 21H Qualification Sample

Savannah River National Laboratory (SRNL) analyzed samples from Tank 21H in support of qualification of Salt Waste Processing Facility (SWPF) Salt Batch 14. This document reports the long-term results of the analyses of the sample of Tank 21H. Analysis of this sample indicates that the material does not display any unusual characteristics or observations, such as visually apparent solids. This report satisfies Deliverable 3 of the Technical Task Request (TTR).

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2026

Advancing SiC clad fuel performance model: bridging micro- and macro-scale models and experimental validation

This report presents a workflow for advancing fuel performance modeling of SiC composite cladding for light-water reactors by linking microscale, experimental data-informed finite element analysis with rod-scale fuel performance codes such as BISON. The workflow uses X-ray computed tomography (XCT) to capture the actual geometry and processing-induced defects of as-fabricated SiC composite tube specimens, particularly porosity and wall-thickness variations, and converts the segmented XCT volumes into image-based finite element meshes for high fidelity structural analysis.

Koyanagi, Takaaki [Oak Ridge National Laboratory (↗
NASA NTRS1976

Fracture in macro-molecules

Techniques available for the observation of molecular bond rupture during fracture of polymers are briefly outlined. Additional pertinent information can also often be inferred from microscopic and macroscopic measures.

Devries, K. L.↗
NASA NTRS1978

A computer program to automatically generate state equations and macro-models

A computer program, PROSE, that produces nonlinear state equations from a simple topological description of an electrical or mechanical network is described. Unnecessary states are also automatically eliminated, so that a simplified terminal circuit model is obtained. The program also prints out the eigenvalues of a linearized system and the sensitivities of the eigenvalue of largest magnitude.

Garrett, S. J.↗
NASA NTRS1985

Multiple muons in MACRO

An analysis of the multiple muon events in the Monopole Astrophysics and Cosmic Ray Observatory detector was conducted to determine the cosmic ray composition. Particular emphasis is placed on the interesting primary cosmic ray energy region above 2000 TeV/nucleus. An extensive study of muon production in cosmic ray showers has been done. Results were used to parameterize the characteristics of muon penetration into the Earth to the location of a detector.

Heinz, R.↗
NASA NTRS1985

Search for stellar collapse with the MACRO detector at Gran Sasso

It is viewed that in stellar evolution stars in the range of 8 to 12 solar masses evolve gradually as increasingly heavier nuclei are produced and then consumed in a series of exothermic thermonuclear processes ultimately leading to the formation of a core composed almost entirely of nickel and iron. When the mass of this hot iron-nickel core reaches the critical value of approximately 1.4 solar masses, electron degeneracy pressure is no longer able to support the outer layers of the star and a collapse process begins. Since the core has exhausted its thermonuclear fuel, further stages of thermonuclear burning cannot prevent a runaway collapse. As the density reaches 10 to the 10th power gm sub/cm at a temperature near 10 to the 10th power k, most of the heavy nuclei are dissociated into free nucleons and electron capture on free protons leads to a decrease in the degeneracy pressure and further acceleration of the collapse process. Although this general picture has received substantial confirmation over the past two decades with the discovery of radio pulsars (neutron stars), X-ray pulsars (accreting binary neutron stars) and Cyg X-1 (probably an accreting black hole), an actual neutrino burst is not yet convincingly detected.

Steinberg, R.↗
NASA NTRS1987

Micro and macro approaches to tough polymers for composites

The progress to date on the development of techniques to toughen continuous thermoplastic composites is summarized. The work, using the approach of toughening the polycarbonate composite matrix with rubber particles, has focused on determining the differences between Double Cantilever Beam (DCB) samples molded inhouse and those molded by NASA. Specifically, an effort was made to account for the differences in fracture toughness observed between the various specimens. In addition, preliminary results of tensile dilatometry tests are described; these tests suggest that processes leading to increased volume and enhanced shear banding are occurring within the rubber toughened system. The results of the effort using another approach, the preparation of random block copolycarbonates, are presented. The synthetic route to these species was modified so that higher molecular weights of these materials can be obtained. In addition, an attempt is being made to determine the exact block length or the number of functional groups in the oligomers since this procedure also should lead to high molecular weight materials. Dynamic mechanical analysis of the copolymer prepared so far indicates that the scale of cooperative molecular motion of the PBA polycarbonate at sub-Tg temperatures is larger than five monomer units. Efforts to find a suitable rubber-toughener for a thermoset system (bismaleimides) is also discussed. Included is a description of the various tougheners intended for use or currently being used.

Yee, Albert F.↗