105 research outputs found
Information-Theoretic Limits on Compression of Semantic Information
As conventional communication systems based on classic information theory
have closely approached the limits of Shannon channel capacity, semantic
communication has been recognized as a key enabling technology for the further
improvement of communication performance. However, it is still unsettled on how
to represent semantic information and characterise the theoretical limits. In
this paper, we consider a semantic source which consists of a set of correlated
random variables whose joint probabilistic distribution can be described by a
Bayesian network. Then we give the information-theoretic limit on the lossless
compression of the semantic source and introduce a low complexity encoding
method by exploiting the conditional independence. We further characterise the
limits on lossy compression of the semantic source and the corresponding upper
and lower bounds of the rate-distortion function. We also investigate the lossy
compression of the semantic source with side information at both the encoder
and decoder, and obtain the rate distortion function. We prove that the optimal
code of the semantic source is the combination of the optimal codes of each
conditional independent set given the side information
Spatial and temporal variation of north-west pacific tropical cyclone under the background of upper ocean warming
879-885Under the background of global warming, the activities of north-west pacific (NWP) tropical cyclones (TCs) are undergoing significant changes. The TC frequencies have been characterized by an initial slow increase followed by a rapid increase and then a decrease, the past 33 years. During the 21st century, the TC frequency of the NWP has clearly decreased. However, the three TC origin types in the NWP have experienced different types of changes. The TC frequencies of origin 1 (10°~22°N,110°~120°E) and origin 2 (8°~20°N,125°~145°E) are both increasing, but the TC frequency of origin 3 (5°~20°N,145°~155°E) is decreasing. Under the background of upper ocean warming, the average TC duration has shown a decreasing trend (-0.27d/10a), while the TC mean and maximum intensity has increased (0.93 m/s/10a and 1.57 m/s/10a, respectively). Therefore, the potential threats of TC activities to NWP coastal countries are likely to intensify. The changes in the thermal state of the upper ocean have many effects on TC activities. Sea surface temperature is not the main factor affecting the frequency of TCs. However, the response of TCs to the upper ocean heat content is obvious
GPT-NAS: Neural Architecture Search with the Generative Pre-Trained Model
Neural Architecture Search (NAS) has emerged as one of the effective methods
to design the optimal neural network architecture automatically. Although
neural architectures have achieved human-level performances in several tasks,
few of them are obtained from the NAS method. The main reason is the huge
search space of neural architectures, making NAS algorithms inefficient. This
work presents a novel architecture search algorithm, called GPT-NAS, that
optimizes neural architectures by Generative Pre-Trained (GPT) model. In
GPT-NAS, we assume that a generative model pre-trained on a large-scale corpus
could learn the fundamental law of building neural architectures. Therefore,
GPT-NAS leverages the generative pre-trained (GPT) model to propose reasonable
architecture components given the basic one. Such an approach can largely
reduce the search space by introducing prior knowledge in the search process.
Extensive experimental results show that our GPT-NAS method significantly
outperforms seven manually designed neural architectures and thirteen
architectures provided by competing NAS methods. In addition, our ablation
study indicates that the proposed algorithm improves the performance of finely
tuned neural architectures by up to about 12% compared to those without GPT,
further demonstrating its effectiveness in searching neural architectures
VCL Challenges 2023 at ICCV 2023 Technical Report: Bi-level Adaptation Method for Test-time Adaptive Object Detection
This report outlines our team's participation in VCL Challenges B Continual
Test_time Adaptation, focusing on the technical details of our approach. Our
primary focus is Testtime Adaptation using bi_level adaptations, encompassing
image_level and detector_level adaptations. At the image level, we employ
adjustable parameterbased image filters, while at the detector level, we
leverage adjustable parameterbased mean teacher modules. Ultimately, through
the utilization of these bi_level adaptations, we have achieved a remarkable
38.3% mAP on the target domain of the test set within VCL Challenges B. It is
worth noting that the minimal drop in mAP, is mearly 4.2%, and the overall
performance is 32.5% mAP
Differences in diversity and community assembly processes between planktonic and benthic diatoms in the upper reach of the Jinsha River, China
Comparing spatio-temporal patterns between planktonic and benthic algae is helpful for understanding their associations and differences. However, such studies are still rare especially in large rivers. We used a dataset collected in the upper reach of the Jinsha River in different seasons to explore biodiversity and assembly processes of planktonic and benthic diatom assemblages. We found that planktonic and benthic diatoms presented different seasonal variation in species richness and community compositions. We also found evidence that planktonic and benthic diatoms were coupled in the summer. Planktonic diatom assemblages were mainly affected by spatial processes via directional spatial dispersal, especially in the summer. By comparison, benthic diatom assemblages were more affected by environmental processes. Our findings suggest that mass effect and species sorting paradigms explain the assembly processes of planktonic and benthic diatom assemblages, respectively, but the explanatory powers of these two paradigms vary seasonally. To effectively monitor and assess ecological conditions of large rivers, we recommend using benthic algae as a biotic indicator group as they had stronger correlations with environmental factors.Peer reviewe
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