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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 703 records · Page 39
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Adjusting padding of graphical charts representing data from multidimensional databases

An exemplary method of displaying a data visualization includes retrieving a dataset that includes a plurality of fields and displaying a graphical user interface with a plurality of shelves. The method further includes receiving user actions to: (i) associate a first field with a first shelf, and (ii) associate a second field with a second shelf; displaying, in accordance with the received user actions, a data visualization, where each data mark has a first size defined according to a default position of a displayed slidable affordance; and receiving an additional user action that moves the slidable affordance from the default position to a user-defined position. In response to receiving the additional user action, the method further includes updating the data visualization, where each data mark included in the updated data visualization has a second size, different from the first size, defined according to the user-defined position of the slidable affordance.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2020

A Mathematical Framework for Representing Cyber-Physical System Interdependencies and Resilience

U.S. critical infrastructure is increasingly composed of integrated cyber-physical systems (CPS) whose components are operationally interdependent. These interdependencies can create additional vulnerabilities beyond those that are typically evaluated through independent physical and cyber risk assessments. These additional vulnerabilities, previously undetected at the sub-system and/or component level, could cause cascading effects across both the physical and cyber domains that could lead to infrastructure disruption or failure. This paper will review an initial mathematical framework developed to help understand the dynamics of these interfacing physical and cyber components at a holistic system level. The resulting framework also provides a method for modeling and assessing the resilience of CPS in complex and adaptive systems. It frames the system in terms of mission performance and the potential effects to performance caused by attacks that are cyber, physical, or blended in nature. The framework utilizes a systems-based, state-space modeling approach to reason about risk, resilience, and interdependencies in CPS. Probabilities are applied to each CPS component regarding a threat (both man-made and natural) and the likelihood of that particular component being impacted, along with indirect impact to other interdependent components. These component-level impacts from threats then translate into mission-level impact and systemic state change.

Brigantic, Robert T.↗
DOE OSTI2019

Nondestructive Evaluation of Concrete Specimens Representative of Nuclear Power Plants Containing Known Defects

Many known defects that develop in concrete over time threaten the safety and security of the infrastructure in nuclear power plants (NPPs). These defects also exist in other concrete infrastructures, but the harsher nuclear environment adds significant difficulty to their detection and correction. To monitor the structural health of a concrete facility, coring and other destructive testing methods are typically employed, but this is not the ideal solution for NPP concrete infrastructure. Developing a reliable nondestructive evaluation (NDE) method to evaluate the damage in these structures will greatly improve the long-term operation and safety of NPPs. The University of Tennessee, in collaboration with Oak Ridge National Laboratory, developed a large-scale experiment to study one known defect due to the reaction between hydroxyl ions of the alkalis in cement paste and the siliceous minerals present in some aggregates known as alkali-silica reactions (ASRs). Alkali-silica gel forms and swells due to its hygroscopic characteristic, causing cracking and material failure. This paper discusses the NDE measurements performed on the large concrete specimens and the reconstructed images from these measurements.

Ezell, N Dianne↗
DOE OSTI2017

Recovering Topology of Nested Volumes Represented by Single Closed Surfaces

As scientific computing abilities continue to advance, so too have the efforts to model and simulate highly complex geometries in radiation environments. Modeling has advanced from primitive constructive solid geometry (CSG) to voxelized models, and now to high fidelity polygon mesh models. While polygon mesh surface models are very accurate, most Monte Carlo codes do not allow for their direct use. Often they are converted to voxel or tetrahedral mesh models and then used with the physics codes. The Direct Accelerated Geometry Monte Carlo (DAGMC) software package has the ability to efficiently run transport calculations directly on tessellated surface models. Typically the surface meshes used for DAGMC calculations come from CAD-based geometry models generated by solid modeling software. In some cases geometries of interest, like human phantoms, are generated by other means and may not contain all of the necessary information for particle transport. For example, mesh geometries in the OBJ file format contain vertex and connectivity data for each surface, but do not have any information about surface topology. These types of file formats necessitate a tool that can build a hierarchy of surfaces and reconstruct the topological information. The generate hierarchy tool was developed for this purpose. The following summary will explain the algorithm behind the tool, describe a test case, and finally demonstrate a real-world application of the tool with an MCNP5 calculation that directly uses a polygon mesh human phantom.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗