195 research outputs found
Quantum phases of the biased two-chain-coupled Bose-Hubbard Ladder
We investigate the quantum phases of bosons in a two-chain-coupled ladder.
This bosonic ladder is generally in a biased configuration, meaning that the
two chains of the ladder can have dramatically different on-site interactions
and potential energies. Adopting the numerical density-matrix
renormalization-group method, we analyze the phase transitions in various
parameter spaces. We find signatures of both insulating-to-superfluid and
superfluid-to-insulating quantum phase transitions as the interchain tunnelling
is increased. Interestingly, tunning the interaction to some intermediate
values, the system can exhibit a reentrant quantum phase transition between
insulating and superfluid phases. We show that for infinite interaction bias,
the model is amenable to some analytical treatments, whose prediction about the
phase boundary is in great agreement with the numerical results. We finally
clarify some critical parameters which separate the system into regimes with
distinct phase behaviours, and briefly compare typical properties of the biased
and unbiased bosonic ladder systems. Our work enriches the Bose-Hubbard
physics.Comment: 10 pages, 7 figure
SelfNeRF: Fast Training NeRF for Human from Monocular Self-rotating Video
In this paper, we propose SelfNeRF, an efficient neural radiance field based
novel view synthesis method for human performance. Given monocular
self-rotating videos of human performers, SelfNeRF can train from scratch and
achieve high-fidelity results in about twenty minutes. Some recent works have
utilized the neural radiance field for dynamic human reconstruction. However,
most of these methods need multi-view inputs and require hours of training,
making it still difficult for practical use. To address this challenging
problem, we introduce a surface-relative representation based on
multi-resolution hash encoding that can greatly improve the training speed and
aggregate inter-frame information. Extensive experimental results on several
different datasets demonstrate the effectiveness and efficiency of SelfNeRF to
challenging monocular videos.Comment: Project page: https://ustc3dv.github.io/SelfNeR
Towards Generative Modeling of Urban Flow through Knowledge-enhanced Denoising Diffusion
Although generative AI has been successful in many areas, its ability to
model geospatial data is still underexplored. Urban flow, a typical kind of
geospatial data, is critical for a wide range of urban applications. Existing
studies mostly focus on predictive modeling of urban flow that predicts the
future flow based on historical flow data, which may be unavailable in
data-sparse areas or newly planned regions. Some other studies aim to predict
OD flow among regions but they fail to model dynamic changes of urban flow over
time. In this work, we study a new problem of urban flow generation that
generates dynamic urban flow for regions without historical flow data. To
capture the effect of multiple factors on urban flow, such as region features
and urban environment, we employ diffusion model to generate urban flow for
regions under different conditions. We first construct an urban knowledge graph
(UKG) to model the urban environment and relationships between regions, based
on which we design a knowledge-enhanced spatio-temporal diffusion model
(KSTDiff) to generate urban flow for each region. Specifically, to accurately
generate urban flow for regions with different flow volumes, we design a novel
diffusion process guided by a volume estimator, which is learnable and
customized for each region. Moreover, we propose a knowledge-enhanced denoising
network to capture the spatio-temporal dependencies of urban flow as well as
the impact of urban environment in the denoising process. Extensive experiments
on four real-world datasets validate the superiority of our model over
state-of-the-art baselines in urban flow generation. Further in-depth studies
demonstrate the utility of generated urban flow data and the ability of our
model for long-term flow generation and urban flow prediction. Our code is
released at: https://github.com/tsinghua-fib-lab/KSTDiff-Urban-flow-generation
IntrinsicNGP: Intrinsic Coordinate based Hash Encoding for Human NeRF
Recently, many works have been proposed to utilize the neural radiance field
for novel view synthesis of human performers. However, most of these methods
require hours of training, making them difficult for practical use. To address
this challenging problem, we propose IntrinsicNGP, which can train from scratch
and achieve high-fidelity results in few minutes with videos of a human
performer. To achieve this target, we introduce a continuous and optimizable
intrinsic coordinate rather than the original explicit Euclidean coordinate in
the hash encoding module of instant-NGP. With this novel intrinsic coordinate,
IntrinsicNGP can aggregate inter-frame information for dynamic objects with the
help of proxy geometry shapes. Moreover, the results trained with the given
rough geometry shapes can be further refined with an optimizable offset field
based on the intrinsic coordinate.Extensive experimental results on several
datasets demonstrate the effectiveness and efficiency of IntrinsicNGP. We also
illustrate our approach's ability to edit the shape of reconstructed subjects.Comment: Project page:https://ustc3dv.github.io/IntrinsicNGP/. arXiv admin
note: substantial text overlap with arXiv:2210.0165
Improving effect of Platycodin D on ethanol-induced fatty liver via Keape-NRF2-are signal path
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