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Chong Tian

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3 papers

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JBHI Journal 2026 Journal Article

Towards Unconstrained Fall Detection Using Vision Language Model: Dataset, Theory and Practices

Shiman Wu
Tianyi Chen
Zhihao Zha
Bin Wu
Yixin Li
Ran Wang
Yanan Li
Chong Tian

Unconstrained fall detection is essential for real-world applications. However, it remains underexplored due to the scarcity of real-world fall data and the limited generalization ability of existing methods. To address these challenges, we first introduce HUST-FALL, a fine-grained text-video dataset for unconstrained fall detection, featuring diverse fall scenarios and rich semantic annotations. Building on this dataset, we propose Action-R1, a lightweight vision-language model that leverages structured textual guidance and reasoning to improve the understanding of fall events. In challenging cross-dataset tests, Action-R1 achieves an average F1 score of 0. 827 on three benchmarks, significantly outperforming conventional CNN/RNN-based methods. Despite having only 1/16 the parameters, Action-R1 achieves competitive performance against MiniCPM-V 2. 6, even surpassing it on UPFall by 116. 22%. These results demonstrate that Action-R1 is a lightweight yet powerful solution for unconstrained fall detection in real-world scenarios.

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UAI Conference 2025 Conference Paper

On the Privacy Risks of Spiking Neural Networks: A Membership Inference Analysis

Junyi Guan
Abhijith Sharma
Chong Tian
Salem Lahlou

Spiking Neural Networks (SNNs) are increasingly explored for their energy efficiency and robustness in real-world applications, yet their privacy risks remain largely unexamined. In this work, we investigate the susceptibility of SNNs to Membership Inference Attacks (MIAs)-a major privacy threat where an adversary attempts to determine whether a given sample was part of the training dataset. While prior work suggests that SNNs may offer inherent robustness due to their discrete, event-driven nature, we find that its resilience diminishes as latency (T) increases. Furthermore, we introduce an input dropout strategy under black box setting, that significantly enhances membership inference in SNNs. Our findings challenge the assumption that SNNs are inherently more secure, and even though they are expected to be better, our results reveal that SNNs exhibit privacy vulnerabilities that are equally comparable to Artificial Neural Networks (ANNs).

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NeurIPS Conference 2023 Conference Paper

FedNAR: Federated Optimization with Normalized Annealing Regularization

Junbo Li
Ang Li
Chong Tian
Qirong Ho
Eric Xing
Hongyi Wang

Weight decay is a standard technique to improve generalization performance in modern deep neural network optimization, and is also widely adopted in federated learning (FL) to prevent overfitting in local clients. In this paper, we first explore the choices of weight decay and identify that weight decay value appreciably influences the convergence of existing FL algorithms. While preventing overfitting is crucial, weight decay can introduce a different optimization goal towards the global objective, which is further amplified in FL due to multiple local updates and heterogeneous data distribution. To address this challenge, we develop {\it Federated optimization with Normalized Annealing Regularization} (FedNAR), a simple yet effective and versatile algorithmic plug-in that can be seamlessly integrated into any existing FL algorithms. Essentially, we regulate the magnitude of each update by performing co-clipping of the gradient and weight decay. We provide a comprehensive theoretical analysis of FedNAR's convergence rate and conduct extensive experiments on both vision and language datasets with different backbone federated optimization algorithms. Our experimental results consistently demonstrate that incorporating FedNAR into existing FL algorithms leads to accelerated convergence and heightened model accuracy. Moreover, FedNAR exhibits resilience in the face of various hyperparameter configurations. Specifically, FedNAR has the ability to self-adjust the weight decay when the initial specification is not optimal, while the accuracy of traditional FL algorithms would markedly decline. Our codes are released at \href{https: //anonymous. 4open. science/r/fednar-BE8F}{https: //anonymous. 4open. science/r/fednar-BE8F}.

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