2,587 research outputs found
Efficient Truss Maintenance in Evolving Networks
Truss was proposed to study social network data represented by graphs. A
k-truss of a graph is a cohesive subgraph, in which each edge is contained in
at least k-2 triangles within the subgraph. While truss has been demonstrated
as superior to model the close relationship in social networks and efficient
algorithms for finding trusses have been extensively studied, very little
attention has been paid to truss maintenance. However, most social networks are
evolving networks. It may be infeasible to recompute trusses from scratch from
time to time in order to find the up-to-date -trusses in the evolving
networks. In this paper, we discuss how to maintain trusses in a graph with
dynamic updates. We first discuss a set of properties on maintaining trusses,
then propose algorithms on maintaining trusses on edge deletions and
insertions, finally, we discuss truss index maintenance. We test the proposed
techniques on real datasets. The experiment results show the promise of our
work
A Fast Order-Based Approach for Core Maintenance
Graphs have been widely used in many applications such as social networks,
collaboration networks, and biological networks. One important graph analytics
is to explore cohesive subgraphs in a large graph. Among several cohesive
subgraphs studied, k-core is one that can be computed in linear time for a
static graph. Since graphs are evolving in real applications, in this paper, we
study core maintenance which is to reduce the computational cost to compute
k-cores for a graph when graphs are updated from time to time dynamically. We
identify drawbacks of the existing efficient algorithm, which needs a large
search space to find the vertices that need to be updated, and has high
overhead to maintain the index built, when a graph is updated. We propose a new
order-based approach to maintain an order, called k-order, among vertices,
while a graph is updated. Our new algorithm can significantly outperform the
state-of-the-art algorithm up to 3 orders of magnitude for the 11 large real
graphs tested. We report our findings in this paper
Incremental Maintenance of Maximal Cliques in a Dynamic Graph
We consider the maintenance of the set of all maximal cliques in a dynamic
graph that is changing through the addition or deletion of edges. We present
nearly tight bounds on the magnitude of change in the set of maximal cliques,
as well as the first change-sensitive algorithms for clique maintenance, whose
runtime is proportional to the magnitude of the change in the set of maximal
cliques. We present experimental results showing these algorithms are efficient
in practice and are faster than prior work by two to three orders of magnitude.Comment: 18 pages, 8 figure
Advancing automation and robotics technology for the space station and for the US economy: Submitted to the United States Congress October 1, 1987
In April 1985, as required by Public Law 98-371, the NASA Advanced Technology Advisory Committee (ATAC) reported to Congress the results of its studies on advanced automation and robotics technology for use on the space station. This material was documented in the initial report (NASA Technical Memorandum 87566). A further requirement of the Law was that ATAC follow NASA's progress in this area and report to Congress semiannually. This report is the fifth in a series of progress updates and covers the period between 16 May 1987 and 30 September 1987. NASA has accepted the basic recommendations of ATAC for its space station efforts. ATAC and NASA agree that the mandate of Congress is that an advanced automation and robotics technology be built to support an evolutionary space station program and serve as a highly visible stimulator affecting the long-term U.S. economy
The Mod-2 wind turbine development project
A major phase of the Federal Wind Energy Program, the Mod-2 wind turbine, a second-generation machine developed by the Boeing Engineering and Construction Co. for the U.S. Department of Energy and the Lewis Research Center of the National Aeronautics and Space Administration, is described. The Mod-2 is a large (2.5-MW power rating) horizontal-axis wind turbine designed for the generation of electrical power on utility networks. Three machines were built and are located in a cluster at Goodnoe Hills, Washington. All technical aspects of the project are described: design approach, significant innovation features, the mechanical system, the electrical power system, the control system, and the safety system
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