569 research outputs found
Stylised procedural animation
This thesis develops a stylised procedural paradigm for computer graphics animation. Cartoon effects animations - stylised representations of natural phenomena - have presented a long-standing, difficult challenge to computer animators. We propose a framework for achieving the intricacy of effects motion with minimal animator intervention.Our approach is to construct cartoon effects by simulating the hand-drawing process through synthetic, computational means. We create a system which emulates the stylish appearance, movements of cartoon effects in both 2D and 3D environments. Our computational models achieve this by capturing the essential characteristics common to all cartoon effects: structure modelling, dynamic controlling and stylised rendering.To validate our framework, we have implemented a cartoon effects system for a range of effects including water effects, fire, smoke, rain and snow. Each effect model has its own static structure such as how the different parts are related temporarily. The flexibility of our approach is suggested most evidently by the high-level controls on shape, colour, timing and rendering on the effects. Like their hand-drawn counterparts, they move consistently while retaining the hand-crafted look.Since the movements of cartoon effects are animated procedurally, their detailed motions need not be keyframed. This thesis therefore demonstrates a powerful approach to computer animation in which the animator plays the role of a high level controller, rather than the more conventional hand-drawing slave. Our work not only achieves cartoon effects animation of un-precedented complexity, but it also provides an interesting experimental domain for related research disciplines toward more creative and expressive image synthesis in animation
Centralized Feature Pyramid for Object Detection
Visual feature pyramid has shown its superiority in both effectiveness and
efficiency in a wide range of applications. However, the existing methods
exorbitantly concentrate on the inter-layer feature interactions but ignore the
intra-layer feature regulations, which are empirically proved beneficial.
Although some methods try to learn a compact intra-layer feature representation
with the help of the attention mechanism or the vision transformer, they ignore
the neglected corner regions that are important for dense prediction tasks. To
address this problem, in this paper, we propose a Centralized Feature Pyramid
(CFP) for object detection, which is based on a globally explicit centralized
feature regulation. Specifically, we first propose a spatial explicit visual
center scheme, where a lightweight MLP is used to capture the globally
long-range dependencies and a parallel learnable visual center mechanism is
used to capture the local corner regions of the input images. Based on this, we
then propose a globally centralized regulation for the commonly-used feature
pyramid in a top-down fashion, where the explicit visual center information
obtained from the deepest intra-layer feature is used to regulate frontal
shallow features. Compared to the existing feature pyramids, CFP not only has
the ability to capture the global long-range dependencies, but also efficiently
obtain an all-round yet discriminative feature representation. Experimental
results on the challenging MS-COCO validate that our proposed CFP can achieve
the consistent performance gains on the state-of-the-art YOLOv5 and YOLOX
object detection baselines.Comment: Code: https://github.com/QY1994-0919/CFPNe
Electromagnetic fields in ultra-peripheral relativistic heavy-ion collisions
Ultra-peripheral heavy-ion collisions (UPC) provide unique opportunities to
study processes under strong electromagnetic fields. Highly-charged moving ions
carry strong electromagnetic fields that act as fields of photons. The exchange
of photons could induce photonuclear and two-photon interactions as well as
excite the ions into giant dipole resonances (GDRs) or even higher excitation.
The GDRs typically decay by emitting photons and even a single neutron, while
high-excited resonances usually decay by emitting two or more photons and/or
neutrons. On the other hand, the electromagnetic fields of heavy ions are very
strong, so one of the two colliding ions is enforced by the other's
electromagnetic field. As a result, the two colliding ions are pushed into
opposite directions by the electromagnetic forces, and thus the neutrons
emitted from different ions could present a back-to-back correlation. Using a
Monte-Carlo simulation implementing the electromagnetic fields as well as the
neutron emission from previous measurements or model calculations, we
qualitatively demonstrate that the above electromagnetic effect is large enough
to be observed in UPC, which would provide a clear means to study the strong
electromagnetic fields and its effects.Comment: 4 pages, 3 figure
Recalibration of the binding energy of hypernuclei measured in emulsion experiments and its implications
The separation energy for -hypernuclei, denoted
, measured in 1967, 1968, and 1973 are recalibrated using the
current best mass estimates for particles and nuclei. The recalibrated
are systematically larger (except in the case of He)
than the original published values by about 100 keV. The effect of this level
of recalibration is very important for light hypernuclei, especially for the
hypertriton. The early values measured in 1967, 1968, and 1973 are
widely used in theoretical research, and the new results provide better
constraints on the conclusions from such studies.Comment: To be published in Chinese Physics
Fiber-optic acoustic pressure sensor based on large-area nanolayer silver diaghragm
This is the published version. © 2014 Optical Society of AmericaA fiber-optic acoustic pressure sensor based on a large-area nanolayer silver diaphragm is demonstrated with a high dynamic pressure sensitivity of 160  nm/Pa at 4 kHz frequency. The sensor exhibits a noise limited detectable pressure level of 14.5  μPa/Hz1/2. Its high dynamic pressure sensitivity and simple fabrication process make it an attractive tool for acoustic sensing and photo-acoustic spectroscopy
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