143 research outputs found
On the dynamics of two photons interacting with a two-qubit coherent feedback network}
The purpose of this paper is to study the dynamics of a quantum coherent
feedback network composed of two two-level systems (qubits) driven by two
counter-propagating photons, one in each input channel. The coherent feedback
network enhances the nonlinear photon-photon interaction inside the feedback
loop. By means of quantum stochastic calculus and the input-output framework,
the analytic form of the steady-state output two-photon state is derived. Based
on the analytic form, the applications on the Hong-Ou-Mandel (HOM)
interferometer and marginally stable single-photon devices using this coherent
feedback structure have been demonstrated. The difference between
continuous-mode and single-mode few-photon states is demonstrated.Comment: 15 pages, 4 figures; accepted by Automatica; comments are welcome
Background Subtraction for Night Videos
Motion analysis is important in video surveillance systems and background subtraction is useful for moving object detection in such systems. However, most of the existing background subtraction methods do not work well for surveillance systems in the evening because objects are usually dark and reflected light is usually strong. To resolve these issues, we propose a framework that utilizes a Weber contrast descriptor, a texture feature extractor, and a light detection unit, to extract the features of foreground objects. We propose a local pattern enhancement method. For the light detection unit, our method utilizes the finding that lighted areas in the evening usually have a low saturation in hue-saturation-value and hue-saturation-lightness color spaces. Finally, we update the background model and the foreground objects in the framework. This approach is able to improve foreground object detection in night videos, which do not need a large data set for pre-training
NeuralMarker: A Framework for Learning General Marker Correspondence
We tackle the problem of estimating correspondences from a general marker,
such as a movie poster, to an image that captures such a marker.
Conventionally, this problem is addressed by fitting a homography model based
on sparse feature matching. However, they are only able to handle plane-like
markers and the sparse features do not sufficiently utilize appearance
information. In this paper, we propose a novel framework NeuralMarker, training
a neural network estimating dense marker correspondences under various
challenging conditions, such as marker deformation, harsh lighting, etc.
Besides, we also propose a novel marker correspondence evaluation method
circumstancing annotations on real marker-image pairs and create a new
benchmark. We show that NeuralMarker significantly outperforms previous methods
and enables new interesting applications, including Augmented Reality (AR) and
video editing.Comment: Accepted by ToG (SIGGRAPH Asia 2022). Project Page:
https://drinkingcoder.github.io/publication/neuralmarker
RD-VIO: Robust Visual-Inertial Odometry for Mobile Augmented Reality in Dynamic Environments
It is typically challenging for visual or visual-inertial odometry systems to
handle the problems of dynamic scenes and pure rotation. In this work, we
design a novel visual-inertial odometry (VIO) system called RD-VIO to handle
both of these two problems. Firstly, we propose an IMU-PARSAC algorithm which
can robustly detect and match keypoints in a two-stage process. In the first
state, landmarks are matched with new keypoints using visual and IMU
measurements. We collect statistical information from the matching and then
guide the intra-keypoint matching in the second stage. Secondly, to handle the
problem of pure rotation, we detect the motion type and adapt the
deferred-triangulation technique during the data-association process. We make
the pure-rotational frames into the special subframes. When solving the
visual-inertial bundle adjustment, they provide additional constraints to the
pure-rotational motion. We evaluate the proposed VIO system on public datasets.
Experiments show the proposed RD-VIO has obvious advantages over other methods
in dynamic environments
Geometric Scaling of the Current-Phase Relation of Niobium Nano-Bridge Junctions
The nano-bridge junction (NBJ) is a type of Josephson junction that is
advantageous for the miniaturization of superconducting circuits. However, the
current-phase relation (CPR) of the NBJ usually deviates from a sinusoidal
function which has been explained by a simplified model with correlation only
to its effective length. Here, we investigated both measured and calculated
CPRs of niobium NBJs of a cuboidal shape with a three-dimensional bank
structure. From a sine-wave to a saw-tooth-like form, we showed that deviated
CPRs of NBJs can be described quantitatively by its skewness {\Delta}{\theta}.
Furthermore, the measured dependency of {\Delta}{\theta} on the critical
current {I_0} from 108 NBJs turned out to be consistent with the calculated
ones derived from the change in geometric dimensions. It suggested that the
CPRs of NBJs can be tuned by their geometric dimensions. In addition, the
calculated scaling behavior of {\Delta}{\theta} versus {I_0} in
three-dimensional space was provided for the future design of superconducting
circuits of a high integration level by using niobium NBJs.Comment: 20 pages, 10 figure
DAB2IP Downregulation Enhances the Proliferation and Metastasis of Human Gastric Cancer Cells by Derepressing the ERK1/2 Pathway
Substantial transition to clean household energy mix in rural China
The household energy mix has significant impacts on human health and climate, as it contributes greatly to many health- and climate-relevant air pollutants. Compared to the well-established urban energy statistical system, the rural household energy statistical system is incomplete and is often associated with high biases. Via a nationwide investigation, this study revealed high contributions to energy supply from coal and biomass fuels in the rural household energy sector, while electricity comprised ∼20%. Stacking (the use of multiple sources of energy) is significant, and the average number of energy types was 2.8 per household. Compared to 2012, the consumption of biomass and coals in 2017 decreased by 45% and 12%, respectively, while the gas consumption amount increased by 204%. Increased gas and decreased coal consumptions were mainly in cooking, while decreased biomass was in both cooking (41%) and heating (59%). The time-sharing fraction of electricity and gases (E&G) for daily cooking grew, reaching 69% in 2017, but for space heating, traditional solid fuels were still dominant, with the national average shared fraction of E&G being only 20%. The non-uniform spatial distribution and the non-linear increase in the fraction of E&G indicated challenges to achieving universal access to modern cooking energy by 2030, particularly in less-developed rural and mountainous areas. In some non-typical heating zones, the increased share of E&G for heating was significant and largely driven by income growth, but in typical heating zones, the time-sharing fraction was <5% and was not significantly increased, except in areas with policy intervention. The intervention policy not only led to dramatic increases in the clean energy fraction for heating but also accelerated the clean cooking transition. Higher income, higher education, younger age, less energy/stove stacking and smaller family size positively impacted the clean energy transition
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