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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 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Impact of Ni and Mg Loadings on Dry Reforming Performance of Pt/Ceria-Zirconia Catalysts

The isolated effects of Ni and Mg on a series of Pt/Ce 0.6 Zr 0.4 O 2 (CZO) reforming catalysts were evaluated and used to formulate an improved catalyst with both Ni and Mg present. The dry reforming reaction results indicate that Ni enhances the CH 4 conversion at low temperatures while Mg improves the H 2 :CO ratio and stability, but requires high temperatures to reach similar conversions. The detection of coke (5.5 X 10 -4 g/g cat •h) over the 2.7Ni-CZO sample led to the examination of the 2.7Ni-0.50Mg-CZO sample. The catalyst activity results and the absence of coke formation over the 2.7Ni-0.50Mg-CZO sample confirmed that both Ni and Mg are needed to obtain a balance between catalyst activity and stability. The catalysts tested yielded low temperature activity with 10 % CH 4 conversions at temperature <500 °C. Furthermore, this work provides key insights into the proper design of low temperature reforming catalysts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Instabilities of Jammed Packings of Frictionless Spheres Under Load

In this work, we consider the contribution to the density of vibrational states and the distribution of energy barrier heights of incipient instabilities in a glass modeled by a jammed packing of spheres. On approaching an instability, the frequency of a normal mode and the height of the energy barrier to cross into a new ground state both vanish. These instabilities produce a contribution to the density of vibrational states that scales as ω 3 at low frequencies ω, and a contribution to the distribution of energy barriers ΔH that scales as ΔH -1/3 at low barrier heights.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2022

Access Patterns and Performance Behaviors of Multi-layer Supercomputer I/O Subsystems under Production Load

Scientific computing workloads at HPC facilities have been shifting from traditional numerical simulations to AI/ML applications for training and inference while processing and producing ever-increasing amounts of scientific data. To address the growing need for increased storage capacity, lower access latency, and higher bandwidth, emerging technologies such as non-volatile memory are integrated into supercomputer I/O subsystems. With these emerging trends, we need a better understanding of the multilayer supercomputer I/O systems and ways to use these subsystems efficiently. In this work, we study the I/O access patterns and performance characteristics of two representative supercomputer I/O subsystems. Through an extensive analysis of year-long I/O logs on each system, we report new observations in I/O reads and writes, unbalanced use of storage system layers, and new trends in user behaviors at the HPC I/O middleware stack.

Bez, JL↗