114 research outputs found
A Finite Time Analysis of Two Time-Scale Actor Critic Methods
Actor-critic (AC) methods have exhibited great empirical success compared
with other reinforcement learning algorithms, where the actor uses the policy
gradient to improve the learning policy and the critic uses temporal difference
learning to estimate the policy gradient. Under the two time-scale learning
rate schedule, the asymptotic convergence of AC has been well studied in the
literature. However, the non-asymptotic convergence and finite sample
complexity of actor-critic methods are largely open. In this work, we provide a
non-asymptotic analysis for two time-scale actor-critic methods under
non-i.i.d. setting. We prove that the actor-critic method is guaranteed to find
a first-order stationary point (i.e., ) of the non-concave performance function
, with sample
complexity. To the best of our knowledge, this is the first work providing
finite-time analysis and sample complexity bound for two time-scale
actor-critic methods.Comment: 45 page
Distinguishing Computer-generated Graphics from Natural Images Based on Sensor Pattern Noise and Deep Learning
Computer-generated graphics (CGs) are images generated by computer software.
The~rapid development of computer graphics technologies has made it easier to
generate photorealistic computer graphics, and these graphics are quite
difficult to distinguish from natural images (NIs) with the naked eye. In this
paper, we propose a method based on sensor pattern noise (SPN) and deep
learning to distinguish CGs from NIs. Before being fed into our convolutional
neural network (CNN)-based model, these images---CGs and NIs---are clipped into
image patches. Furthermore, three high-pass filters (HPFs) are used to remove
low-frequency signals, which represent the image content. These filters are
also used to reveal the residual signal as well as SPN introduced by the
digital camera device. Different from the traditional methods of distinguishing
CGs from NIs, the proposed method utilizes a five-layer CNN to classify the
input image patches. Based on the classification results of the image patches,
we deploy a majority vote scheme to obtain the classification results for the
full-size images. The~experiments have demonstrated that (1) the proposed
method with three HPFs can achieve better results than that with only one HPF
or no HPF and that (2) the proposed method with three HPFs achieves 100\%
accuracy, although the NIs undergo a JPEG compression with a quality factor of
75.Comment: This paper has been published by Sensors. doi:10.3390/s18041296;
Sensors 2018, 18(4), 129
DNAGPT: A Generalized Pre-trained Tool for Versatile DNA Sequence Analysis Tasks
Pre-trained large language models demonstrate potential in extracting
information from DNA sequences, yet adapting to a variety of tasks and data
modalities remains a challenge. To address this, we propose DNAGPT, a
generalized DNA pre-training model trained on over 200 billion base pairs from
all mammals. By enhancing the classic GPT model with a binary classification
task (DNA sequence order), a numerical regression task (guanine-cytosine
content prediction), and a comprehensive token language, DNAGPT can handle
versatile DNA analysis tasks while processing both sequence and numerical data.
Our evaluation of genomic signal and region recognition, mRNA abundance
regression, and artificial genomes generation tasks demonstrates DNAGPT's
superior performance compared to existing models designed for specific
downstream tasks, benefiting from pre-training using the newly designed model
structure
Description of three new Bisetocreagris species (Pseudoscorpiones: Neobisiidae) from Southern China
Three new Bisetocreagris species are described from southern
China: Bisetocreagris shunhuangensis sp. n. from Hunan
Province, B. wangi sp. n. and B. gaoi sp. n. from Guizhou
Province. Detailed diagnoses, descriptions and illustrations of
the three new species are presented
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