12,917 research outputs found
Multiscale Snapshots: Visual Analysis of Temporal Summaries in Dynamic Graphs
The overview-driven visual analysis of large-scale dynamic graphs poses a
major challenge. We propose Multiscale Snapshots, a visual analytics approach
to analyze temporal summaries of dynamic graphs at multiple temporal scales.
First, we recursively generate temporal summaries to abstract overlapping
sequences of graphs into compact snapshots. Second, we apply graph embeddings
to the snapshots to learn low-dimensional representations of each sequence of
graphs to speed up specific analytical tasks (e.g., similarity search). Third,
we visualize the evolving data from a coarse to fine-granular snapshots to
semi-automatically analyze temporal states, trends, and outliers. The approach
enables to discover similar temporal summaries (e.g., recurring states),
reduces the temporal data to speed up automatic analysis, and to explore both
structural and temporal properties of a dynamic graph. We demonstrate the
usefulness of our approach by a quantitative evaluation and the application to
a real-world dataset.Comment: IEEE Transactions on Visualization and Computer Graphics (TVCG), to
appea
WFIRST Coronagraph Technology Requirements: Status Update and Systems Engineering Approach
The coronagraphic instrument (CGI) on the Wide-Field Infrared Survey
Telescope (WFIRST) will demonstrate technologies and methods for high-contrast
direct imaging and spectroscopy of exoplanet systems in reflected light,
including polarimetry of circumstellar disks. The WFIRST management and CGI
engineering and science investigation teams have developed requirements for the
instrument, motivated by the objectives and technology development needs of
potential future flagship exoplanet characterization missions such as the NASA
Habitable Exoplanet Imaging Mission (HabEx) and the Large UV/Optical/IR
Surveyor (LUVOIR). The requirements have been refined to support
recommendations from the WFIRST Independent External Technical/Management/Cost
Review (WIETR) that the WFIRST CGI be classified as a technology demonstration
instrument instead of a science instrument. This paper provides a description
of how the CGI requirements flow from the top of the overall WFIRST mission
structure through the Level 2 requirements, where the focus here is on
capturing the detailed context and rationales for the CGI Level 2 requirements.
The WFIRST requirements flow starts with the top Program Level Requirements
Appendix (PLRA), which contains both high-level mission objectives as well as
the CGI-specific baseline technical and data requirements (BTR and BDR,
respectively)... We also present the process and collaborative tools used in
the L2 requirements development and management, including the collection and
organization of science inputs, an open-source approach to managing the
requirements database, and automating documentation. The tools created for the
CGI L2 requirements have the potential to improve the design and planning of
other projects, streamlining requirement management and maintenance. [Abstract
Abbreviated]Comment: 16 pages, 4 figure
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