342 research outputs found
Bound Controller for a Quadruped Robot using Pre-Fitting Deep Reinforcement Learning
The bound gait is an important gait in quadruped robot locomotion. It can be
used to cross obstacles and often serves as transition mode between trot and
gallop. However, because of the complexity of the models, the bound gait built
by the conventional control method is often unnatural and slow to compute. In
the present work, we introduce a method to achieve the bound gait based on
model-free pre-fit deep reinforcement learning (PF-DRL). We first constructed a
net with the same structure as an actor net in the PPO2 and pre-fit it using
the data collected from a robot using conventional model-based controller.
Next, the trained weights are transferred into the PPO2 and be optimized
further. Moreover, target on the symmetrical and periodic characteristic during
bounding, we designed a reward function based on contact points. We also used
feature engineering to improve the input features of the DRL model and improve
performance on flat ground. Finally, we trained the bound controller in
simulation and successfully deployed it on the Jueying Mini robot. It performs
better than the conventional method with higher computational efficiency and
more stable center-of-mass height in our experiments.Comment: 7page
MCP: Self-supervised Pre-training for Personalized Chatbots with Multi-level Contrastive Sampling
Personalized chatbots focus on endowing the chatbots with a consistent
personality to behave like real users and further act as personal assistants.
Previous studies have explored generating implicit user profiles from the
user's dialogue history for building personalized chatbots. However, these
studies only use the response generation loss to train the entire model, thus
it is prone to suffer from the problem of data sparsity. Besides, they
overemphasize the final generated response's quality while ignoring the
correlations and fusions between the user's dialogue history, leading to rough
data representations and performance degradation. To tackle these problems, we
propose a self-supervised learning framework MCP for capturing better
representations from users' dialogue history for personalized chatbots.
Specifically, we apply contrastive sampling methods to leverage the supervised
signals hidden in user dialog history, and generate the pre-training samples
for enhancing the model. We design three pre-training tasks based on three
types of contrastive pairs from user dialogue history, namely response pairs,
sequence augmentation pairs, and user pairs. We pre-train the utterance encoder
and the history encoder towards the contrastive objectives and use these
pre-trained encoders for generating user profiles while personalized response
generation. Experimental results on two real-world datasets show a significant
improvement in our proposed model MCP compared with the existing methods
A sequential inspection and replacement policy for degradation-based systems
© 2017 IEEE. Condition-based maintenance (CBM) has been extensively studied. However, the majority of existing CBM research either consider a periodic inspection schedule or a fixed preventive maintenance threshold. While policies with periodic inspections and/or fixed maintenance threshold are easy to implement in practice, they may incur more-than-necessary inspections and induce more failures. In this paper, we develop a sequential CBM policy for systems subject to stochastic degradation. The aim of the proposed policy is to prevent or delay failures and perform maintenance activities just in time. Unlike conventional preventive maintenance that often fixes the inspection interval and the preventive maintenance threshold, both the next inspection time and the corresponding maintenance threshold in this paper are dynamically determined based on the current state of the system. The proposed sequential predictive maintenance policy is particularly important and applicable for general non-homogeneous degradation processes. The proposed model enables optimal scheduling of inspection and preventive maintenance decisions, in order to minimize the long-run maintenance cost rate including inspection, preventive and corrective maintenance costs. The performance of the proposed predictive maintenance policy is evaluated using a simulation-based optimization approach. Frequency of system failures and total maintenance cost rates are computed and compared with a bench mark maintenance policy, a periodic inspection/replacement policy. Our results show that there can be potential savings from the proposed predictive maintenance policy
Now and Future of Artificial Intelligence-based Signet Ring Cell Diagnosis: A Survey
Since signet ring cells (SRCs) are associated with high peripheral metastasis
rate and dismal survival, they play an important role in determining surgical
approaches and prognosis, while they are easily missed by even experienced
pathologists. Although automatic diagnosis SRCs based on deep learning has
received increasing attention to assist pathologists in improving the
diagnostic efficiency and accuracy, the existing works have not been
systematically overviewed, which hindered the evaluation of the gap between
algorithms and clinical applications. In this paper, we provide a survey on SRC
analysis driven by deep learning from 2008 to August 2023. Specifically, the
biological characteristics of SRCs and the challenges of automatic
identification are systemically summarized. Then, the representative algorithms
are analyzed and compared via dividing them into classification, detection, and
segmentation. Finally, for comprehensive consideration to the performance of
existing methods and the requirements for clinical assistance, we discuss the
open issues and future trends of SRC analysis. The retrospect research will
help researchers in the related fields, particularly for who without medical
science background not only to clearly find the outline of SRC analysis, but
also gain the prospect of intelligent diagnosis, resulting in accelerating the
practice and application of intelligent algorithms
Hollow mesoporous zeolite microspheres: hierarchical macro-/meso-/ microporous structure and exceptionally enhanced adsorption properties
Exploring Open-Vocabulary Semantic Segmentation without Human Labels
Semantic segmentation is a crucial task in computer vision that involves
segmenting images into semantically meaningful regions at the pixel level.
However, existing approaches often rely on expensive human annotations as
supervision for model training, limiting their scalability to large, unlabeled
datasets. To address this challenge, we present ZeroSeg, a novel method that
leverages the existing pretrained vision-language (VL) model (e.g. CLIP) to
train open-vocabulary zero-shot semantic segmentation models. Although acquired
extensive knowledge of visual concepts, it is non-trivial to exploit knowledge
from these VL models to the task of semantic segmentation, as they are usually
trained at an image level. ZeroSeg overcomes this by distilling the visual
concepts learned by VL models into a set of segment tokens, each summarizing a
localized region of the target image. We evaluate ZeroSeg on multiple popular
segmentation benchmarks, including PASCAL VOC 2012, PASCAL Context, and COCO,
in a zero-shot manner (i.e., no training or adaption on target segmentation
datasets). Our approach achieves state-of-the-art performance when compared to
other zero-shot segmentation methods under the same training data, while also
performing competitively compared to strongly supervised methods. Finally, we
also demonstrated the effectiveness of ZeroSeg on open-vocabulary segmentation,
through both human studies and qualitative visualizations
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