6,621 research outputs found
Topological phases protected by point group symmetry
We consider symmetry protected topological (SPT) phases with crystalline
point group symmetry, dubbed point group SPT (pgSPT) phases. We show that such
phases can be understood in terms of lower-dimensional topological phases with
on-site symmetry, and can be constructed as stacks and arrays of these
lower-dimensional states. This provides the basis for a general framework to
classify and characterize bosonic and fermionic pgSPT phases, that can be
applied for arbitrary crystalline point group symmetry and in arbitrary spatial
dimension. We develop and illustrate this framework by means of a few examples,
focusing on three-dimensional states. We classify bosonic pgSPT phases and
fermionic topological crystalline superconductors with (reflection)
symmetry, electronic topological crystalline insulators (TCIs) with symmetry, and bosonic pgSPT phases with symmetry,
which is generated by two perpendicular mirror reflections. We also study
surface properties, with a focus on gapped, topologically ordered surface
states. For electronic TCIs we find a classification, where
the corresponds to known states obtained from non-interacting electrons,
and the corresponds to a "strongly correlated" TCI that requires strong
interactions in the bulk. Our approach may also point the way toward a general
theory of symmetry enriched topological (SET) phases with crystalline point
group symmetry.Comment: v2: Minor changes/additions to introduction and discussion sections,
references added, published version. 21 pages, 11 figure
Damping effects of different shock absorbing materials for tunnel under seismic loadings
Circular tunnels are widely used in infrastructure. Under the action of earthquakes, the destruction of circular tunnels will result in a large number of economic losses and casualties. Therefore, the study on shock absorption of tunnels is important. However, the research has not been sufficient on the effect of the damping layer on seismic response of a circular tunnel in sand. In this paper, the influence of the damping layer on the seismic response characteristics of circular tunnels in sand is studied by large-scale shaking table test. The actual El-centro wave is loaded to the model system in three directions during the tests. The input peak seismic acceleration values are 0.05Â g, 0.1Â g and 0.2Â g. Then the effects of two different damping materials on the dynamic response characteristics of circular tunnels are analysed quantitatively. The test results show that the damping layer reduces the seismic response of the circular tunnel. The response accelerations of the tunnel bottom and crown without damping layer are greater than that with the damping layer, which indicates that damping layer absorbs the energy caused by the seismic motion. When the sponge rubber is used, the circular tunnel dynamic response is more attenuated than that with foam board. In conclusion, the shock absorbing layer can effectively reduce the seismic response of tunnel. As a result, the damage of the tunnel decreases under the earthquake. This study has clarified the isolation mechanism of the shock absorbing materials. It is recommended to use sponge rubber material as the shock absorbing layer
A Graph Isomorphism Network with Weighted Multiple Aggregators for Speech Emotion Recognition
Speech emotion recognition (SER) is an essential part of human-computer
interaction. In this paper, we propose an SER network based on a Graph
Isomorphism Network with Weighted Multiple Aggregators (WMA-GIN), which can
effectively handle the problem of information confusion when neighbour nodes'
features are aggregated together in GIN structure. Moreover, a Full-Adjacent
(FA) layer is adopted for alleviating the over-squashing problem, which is
existed in all Graph Neural Network (GNN) structures, including GIN.
Furthermore, a multi-phase attention mechanism and multi-loss training strategy
are employed to avoid missing the useful emotional information in the stacked
WMA-GIN layers. We evaluated the performance of our proposed WMA-GIN on the
popular IEMOCAP dataset. The experimental results show that WMA-GIN outperforms
other GNN-based methods and is comparable to some advanced non-graph-based
methods by achieving 72.48% of weighted accuracy (WA) and 67.72% of unweighted
accuracy (UA).Comment: Accepted by Interspeech 202
Individualized Storyline-based News Topic Retrospection
It takes a great effort for common news readers to track events promptly, and not to mention that they can retrospect them precisely after it occurred for a long time period. Although topic detection and tracking techniques have been developed to promptly identify and keep track of similar events in a topic and monitor their progress, the cognitive load remains for a reader to digest these reports. A storyline-based summarization may facilitate readers to recall occurred events in a topic by extracting informative sentences of news reports to compose a concise summary with essential episodes. This paper proposes SToRe (Story-line based Topic Retrospection), that identifies events from news reports and composes a storyline summary to portray the event evolution in a topic. It consists of three main functions: event identification, main storyline construction and storyline-based summarization. The main storyline guides the extraction of representative sentences from news articles to summarize occurred events. This study demonstrates that different topic term sets result in different storylines, and in turn, different summaries. This adaptation is useful for users to review occurred news topics in different storylines
A characterization of graphs with rank 5
AbstractThe rank of a graph G is defined to be the rank of its adjacency matrix. In this paper, we consider the following problem: what is the structure of a connected graph G with rank 5? or equivalently, what is the structure of a connected n-vertex graph G whose adjacency matrix has nullity n-5? In this paper, we completely characterize connected graphs G whose adjacency matrix has rank 5
- …