29,434 research outputs found
Predictive protocol of flocks with small-world connection pattern
By introducing a predictive mechanism with small-world connections, we
propose a new motion protocol for self-driven flocks. The small-world
connections are implemented by randomly adding long-range interactions from the
leader to a few distant agents, namely pseudo-leaders. The leader can directly
affect the pseudo-leaders, thereby influencing all the other agents through
them efficiently. Moreover, these pseudo-leaders are able to predict the
leader's motion several steps ahead and use this information in decision making
towards coherent flocking with more stable formation. It is shown that drastic
improvement can be achieved in terms of both the consensus performance and the
communication cost. From the industrial engineering point of view, the current
protocol allows for a significant improvement in the cohesion and rigidity of
the formation at a fairly low cost of adding a few long-range links embedded
with predictive capabilities. Significantly, this work uncovers an important
feature of flocks that predictive capability and long-range links can
compensate for the insufficiency of each other. These conclusions are valid for
both the attractive/repulsive swarm model and the Vicsek model.Comment: 10 pages, 12 figure
Siamese Instance Search for Tracking
In this paper we present a tracker, which is radically different from
state-of-the-art trackers: we apply no model updating, no occlusion detection,
no combination of trackers, no geometric matching, and still deliver
state-of-the-art tracking performance, as demonstrated on the popular online
tracking benchmark (OTB) and six very challenging YouTube videos. The presented
tracker simply matches the initial patch of the target in the first frame with
candidates in a new frame and returns the most similar patch by a learned
matching function. The strength of the matching function comes from being
extensively trained generically, i.e., without any data of the target, using a
Siamese deep neural network, which we design for tracking. Once learned, the
matching function is used as is, without any adapting, to track previously
unseen targets. It turns out that the learned matching function is so powerful
that a simple tracker built upon it, coined Siamese INstance search Tracker,
SINT, which only uses the original observation of the target from the first
frame, suffices to reach state-of-the-art performance. Further, we show the
proposed tracker even allows for target re-identification after the target was
absent for a complete video shot.Comment: This paper is accepted to the IEEE Conference on Computer Vision and
Pattern Recognition, 201
The low-noise optimisation method for gearbox in consideration of operating conditions
This paper presents a comprehensive procedure to calculate the steady dynamic response and the noise radiation generated from a stepping-down gearbox. In this process, the dynamic model of the cylindrical gear transmission system is built with the consideration of the time-varying mesh stiffness, gear errors and bearing supporting, while the data of dynamic bearing force is obtained through solving the model. Furthermore, taking the data of bearing force as the excitation, the gearbox vibrations and noise radiation are calculated by numerical simulation, and then the time history of node dynamic response, noise spectrum and resonance frequency range of the gearbox are obtained. Finally, the gearbox panel acoustic contribution at the resonance frequency range is calculated. Based on the conclusions from the gearbox panel acoustic contribution analyses and the mode shapes, two gearbox stiffness improving plans have been studied. By contrastive analysis of gearbox noise radiation, the effectiveness of the improving plans is confirmed. This study has provided useful theoretical guideline to the gearbox design
Dark matter coupling to electroweak gauge and Higgs bosons: an effective field theory approach
If dark matter is a new species of particle produced in the early universe as
a cold thermal relic (a weakly-interacting massive particle-WIMP), its present
abundance, its scattering with matter in direct-detection experiments, its
present-day annihilation signature in indirect-detection experiments, and its
production and detection at colliders, depend crucially on the WIMP coupling to
standard-model (SM) particles. It is usually assumed that the WIMP couples to
the SM sector through its interactions with quarks and leptons. In this paper
we explore the possibility that the WIMP coupling to the SM sector is via
electroweak gauge and Higgs bosons. In the absence of an ultraviolet-complete
particle-physics model, we employ effective field theory to describe the
WIMP--SM coupling. We consider both scalars and Dirac fermions as possible
dark-matter candidates. Starting with an exhaustive list of operators up to
dimension 8, we present detailed calculation of dark-matter annihilations to
all possible final states, including gamma gamma, gamma Z, gamma h, ZZ, Zh, W+
W-, hh, and f fbar, and demonstrate the correlations among them. We compute the
mass scale of the effective field theory necessary to obtain the correct
dark-matter mass density, and well as the resulting photon line signals
High resolution cathodoluminescence hyperspectral imaging of surface features in InGaN/GaN multiple quantum well structures
InGaN/GaN multiple quantum wells (MQWs) have been studied by using
cathodoluminescence hyperspectral imaging with high spatial resolution.
Variations in peak emission energies and intensities across trench-like
features and V-pits on the surface of the MQWs are investigated. The MQW
emission from the region inside trench-like features is red-shifted by
approximately 45 meV and more intense than the surrounding planar regions of
the sample, whereas emission from the V-pits is blue-shifted by about 20 meV
and relatively weaker. By employing this technique to the studied
nanostructures it is possible to investigate energy and intensity shifts on a
10 nm length scale.Comment: 3 pages, 3 figure
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