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Multi-Granular Trend Detection for Time-Series Analysis
Time series (such as stock prices) and ensembles (such as model runs for weather forecasts) are two important types of one-dimensional time-varying data. Such data is readily available in large quantities but visual analysis of the raw data quickly becomes infeasible, even for moderately sized data sets. Trend detection is an effective way to simplify time-varying data and to summarize salient information for visual display and interactive analysis. We propose a geometric model for trend-detection in one-dimensional time-varying data, inspired by topological grouping structures for moving objects in two- or higher-dimensional space. Our model gives provable guarantees on the trends detected and uses three natural parameters: granularity, support-size, and duration. These parameters can be changed on-demand. Our system also supports a variety of selection brushes and a time-sweep to facilitate refined searches and interactive visualization of (sub-)trends. We explore different visual styles and interactions through which trends, their persistence, and evolution can be explored
Mesh sensitivity in discrete element simulation of flexible protection structures
The Discrete Element Method (DEM) has been employed in recent years to simulate flexible protection structures undergoing dynamic loading due to its inherent aptitude for dealing with inertial effects and large deformations. The individual structural elements are discretized with an arbitrary number of discrete elements, connected by spring-like remote interactions. In this work, we implement this approach using the parallel bond contact model and compare the numerical results at different discretization intervals with the analytical solutions of classical beam theory. Successively, we use the same model to simulate the punching test of a steel wire mesh and quantify the influence of a different number of elements on the macroscopic response
Res2Net: A New Multi-scale Backbone Architecture
Representing features at multiple scales is of great importance for numerous
vision tasks. Recent advances in backbone convolutional neural networks (CNNs)
continually demonstrate stronger multi-scale representation ability, leading to
consistent performance gains on a wide range of applications. However, most
existing methods represent the multi-scale features in a layer-wise manner. In
this paper, we propose a novel building block for CNNs, namely Res2Net, by
constructing hierarchical residual-like connections within one single residual
block. The Res2Net represents multi-scale features at a granular level and
increases the range of receptive fields for each network layer. The proposed
Res2Net block can be plugged into the state-of-the-art backbone CNN models,
e.g., ResNet, ResNeXt, and DLA. We evaluate the Res2Net block on all these
models and demonstrate consistent performance gains over baseline models on
widely-used datasets, e.g., CIFAR-100 and ImageNet. Further ablation studies
and experimental results on representative computer vision tasks, i.e., object
detection, class activation mapping, and salient object detection, further
verify the superiority of the Res2Net over the state-of-the-art baseline
methods. The source code and trained models are available on
https://mmcheng.net/res2net/.Comment: 11 pages, 7 figure
Magnetic pattern at supergranulation scale: the Void Size Distribution
The large-scale magnetic pattern of the quiet sun is dominated by the
magnetic network. This network, created by photospheric magnetic fields swept
into convective downflows, delineates the boundaries of large scale cells of
overturning plasma and exhibits voids in magnetic organization. Such voids
include internetwork fields, a mixed-polarity sparse field that populate the
inner part of network cells. To single out voids and to quantify their
intrinsic pattern a fast circle packing based algorithm is applied to 511
SOHO/MDI high resolution magnetograms acquired during the outstanding solar
activity minimum between 23 and 24 cycles. The computed Void Distribution
Function shows a quasi-exponential decay behavior in the range 10-60 Mm. The
lack of distinct flow scales in such a range corroborates the hypothesis of
multi-scale motion flows at the solar surface. In addition to the
quasi-exponential decay we have found that the voids reveal departure from a
simple exponential decay around 35 Mm.Comment: 6 pages, 8 figures, to appear in Astronomy and Astrophysic
Pair separation of magnetic elements in the quiet Sun
The dynamic properties of the quiet Sun photosphere can be investigated by
analyzing the pair dispersion of small-scale magnetic fields (i.e., magnetic
elements).
By using hr-long Hinode magnetograms at high spatial resolution
(), we tracked magnetic element pairs within a supergranular
cell near the disk center.
The computed pair separation spectrum, calculated on the whole set of
particle pairs independently of their initial separation, points out what is
known as a super-diffusive regime with spectral index , in
agreement with the most recent literature, but extended to unprecedented
spatial and temporal scales (from granular to supergranular). Furthermore, for
the first time, we investigated here the spectrum of the mean square
displacement of pairs of magnetic elements, depending on their initial
separation . We found that there is a typical initial distance above
(below) which the pair separation is faster (slower) than the average. A
possible physical interpretation of such a typical spatial scale is also
provided
Silicon Photomultipliers in Particle and Nuclear Physics
Following first large-scale applications in highly granular calorimeters and
in neutrino detectors, Silicon Photomultipliers have seen a wide adoption in
accelerator-based particle and nuclear physics experiments. Today, they are
used for a wide range of different particle detector types, ranging from
calorimeters and trackers to particle identification and veto detectors, large
volume detectors for neutrino physics and timing systems. This article reviews
the current state and expected evolution of these applications, highlighting
strengths and limitation of SiPMs and the corresponding design choices in the
respective contexts. General trends and adopted technical solutions in the
applications are discussed.Comment: 17 pages, 18 figures, review paper published in Nuclear Instruments
and Methods A; v2 correcting a missing figure link in tex
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