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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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Fragment-Based Ab Initio Phasing of Peptidic Nanocrystals by MicroED
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Localized Strain Measurement in Molecular Beam Epitaxially Grown Chalcogenide Thin Films by Micro-Raman Spectroscopy
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Environmental cell for in situ X-ray synchrotron micro-CT imaging with simultaneous acoustic measurements
Synchrotron radiation provides the necessary spatial and temporal resolution for non-invasive operando studies of dynamic processes under complex environmental conditions. Here a new environmental cell for simultaneous in situ dynamic X-ray imaging and measuring acoustic properties of geological samples is presented. The primary purpose of this cell is to study gas-hydrate formation in porous geo-materials and its influence on their acoustic properties. The cell is designed for cylindrical samples of 9 mm in diameter, confining and pore pressures up to 12 MPa, and temperatures from –20°C to room temperature. The cell is portable and can be easily assembled and operated at different X-ray sources. This cell enables a wide range of experiments studying physical/chemical processes in the Earth subsurface that change the mechanical properties of rocks (geochemical reactions, phase transitions, etc.).
The Sealing Mechanisms of a Fracture in Opalinus Clay as Revealed by in situ Synchrotron X-Ray Micro-Tomography
The detailed mechanisms of the sealing of a single fracture, from hydration to almost complete closure by increase of confining pressure, as monitored from in situ synchrotron X-ray microtomography during the flow of carbonated water, is here shown for the first time. Different mechanisms play the key role at different stages in the evolution of the fracture. Hydration mechanically weakens the surfaces of the fracture and induces a first closure due to microcracking at the asperity contacts, increasing their size and creating choke points. Increase in confining stress promptly hydraulically seals the fracture by closing the main choke point, with a relative small deformation of the sample. Finally, the more pervasive mechanical deformation observed at higher stresses almost completely seals the whole fracture. The evolution of the sample has been described and quantified using 4D image processing, focusing on the evolution of aperture and digital volume correlation. Hydraulic properties of the sample at different stages have been modeled via Stokes flow simulation, and the results compared to the morphometric analysis, finding positive correlations with the average fracture aperture variation along the flowpath in function of confining pressure. Opalinus Clay is found to be a rock markedly prone to sealing in case of flow with carbonated water; this behavior is the result of the large fraction of clays and of its microstructure, lacking both cementing phases and large stiff particles. CO2 in this sample has no evident role in the evolution of the fracture; chemically induced weathering on the surface has not been detected, in contrast with the behavior observed in samples with carbonates as cementing phase.
Micro-control actions of segmented actuators laminated on paraboloidal shell reflectors
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Micro power sources: objectives
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Micro-Precision Interferometer: Scoreboard on Technology Readiness for the Space Interferometer Mission
We investigate how the Space Interferometry Mission (SIM) will be able to meet some of its instrument astrometrics requirements.
An Overview of NASA's Activities in Micro-Nano Technologies
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An Overview of NASA's Activities in Micro-Nano Technologies
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An overview of NASA's activities in micro-nano technologies
An examination of how mass is used in spacecraft design indicates that technology efforts directed only to reduce the mass of electronics, both digital and analog will not significantly reduce the mass of a spacecraft, regardless of how much success those efforts achieve.
The Vaporizing Liquid Micro-Thruster: Proof of Principle and Preliminary Thermal Characterization
A microfabricated vaporizing liquid thruster was constructed and successfully tested for the first time.
Micro-Precision Interferometer: A Method to Evaluate Disturbance Isolation Solutions
This paper describes a benchmark to assess performance of six-axis vibration isolation systems.
Modified Cohesive Crack Model Adapted for Description of Interface Facture at Micro, Meso, and Macro-Scales
One of the basic assumptions underlying all cohesive crack models used in the description of inelastic fracture has to do with the shape of the cohesive force distribution.
Micro Explorers
Inspired by the world of insects and animals, the well-proven natural 'explorers' on this planet, this study is a fesibility assesment of building efficient and cost-effective 'microexplorers' for future NASA missions.
The Mars Microprobe Mission Advanced Micro-Avionics for Exploration of the Martian Surfaces
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Microscope-on-Chip Using Micro-Channel and Solid State
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