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2,249 results on '"Xie, Qian"'

1. MGDepth: Motion-Guided Cost Volume For Self-Supervised Monocular Depth In Dynamic Scenarios

Author

Zhou, Kaichen, Zhong, Jia-Xing, Bian, Jia-Wang, Xie, Qian, Zheng, Jian-Qing, Trigoni, Niki, and Markham, Andrew

Subjects
Computer Science - Computer Vision and Pattern Recognition
Abstract

Despite advancements in self-supervised monocular depth estimation, challenges persist in dynamic scenarios due to the dependence on assumptions about a static world. In this paper, we present MGDepth, a Motion-Guided Cost Volume Depth Net, to achieve precise depth estimation for both dynamic objects and static backgrounds, all while maintaining computational efficiency. To tackle the challenges posed by dynamic content, we incorporate optical flow and coarse monocular depth to create a novel static reference frame. This frame is then utilized to build a motion-guided cost volume in collaboration with the target frame. Additionally, to enhance the accuracy and resilience of the network structure, we introduce an attention-based depth net architecture to effectively integrate information from feature maps with varying resolutions. Compared to methods with similar computational costs, MGDepth achieves a significant reduction of approximately seven percent in root-mean-square error for self-supervised monocular depth estimation on the KITTI-2015 dataset.

Published
2023

3. Ethylenedioxythiophene‐based Small Molecular Donor with Multiple Conformation Locks for Organic Solar Cells with Efficiency of 19.3%

Author

Xie, Qian, primary, Deng, Xiangmeng, additional, Zhao, Chaowei, additional, Fang, Jie, additional, Xia, Dongdong, additional, Zhang, Yuefeng, additional, Ding, Feng, additional, Wang, Jiali, additional, Li, Mengdi, additional, Zhang, Zhou, additional, Xiao, Chengyi, additional, Liao, Xunfan, additional, Jiang, Lang, additional, Huang, Bin, additional, Dai, Runying, additional, and Li, Weiwei, additional

Published
2024
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12. Accelerating relaxation through Liouvillian exceptional point

Author

Zhou, Yan-Li, Yu, Xiao-Die, Wu, Chun-Wang, Li, Xie-Qian, Zhang, Jie, Li, Weibin, and Chen, Ping-Xing

Subjects
Quantum Physics
Abstract

We investigate speeding up of relaxation of Markovian open quantum systems with the Liouvillian exceptional point (LEP), where the slowest decay mode degenerate with a faster decay mode. The degeneracy significantly increases the gap of the Liouvillian operator, which determines the timescale of such systems in converging to stationarity, and hence accelerates the relaxation process. We explore an experimentally relevant three level atomic system, whose eigenmatrices and eigenspectra are obtained completely analytically. This allows us to gain insights in the LEP and examine respective dynamics with details. We illustrate that the gap can be further widened through Floquet engineering, which further accelerates the relaxation process. Finally, we extend this approach to analyze laser cooling of trapped ions, where vibrations (phonons) couple to the electronic states. An optimal cooling condition is obtained analytically, which agrees with both existing experiments and numerical simulations. Our study provides analytical insights in understanding LEP, as well as in controlling and optimizing dissipative dynamics of atoms and trapped ions.

Published
2023
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15. Smooth Non-Stationary Bandits

Author

Jia, Su, Xie, Qian, Kallus, Nathan, and Frazier, Peter I.

Subjects
Computer Science - Machine Learning, Computer Science - Artificial Intelligence, Mathematics - Optimization and Control, Mathematics - Statistics Theory
Abstract

In many applications of online decision making, the environment is non-stationary and it is therefore crucial to use bandit algorithms that handle changes. Most existing approaches are designed to protect against non-smooth changes, constrained only by total variation or Lipschitzness over time, where they guarantee $\tilde \Theta(T^{2/3})$ regret. However, in practice environments are often changing {\bf smoothly}, so such algorithms may incur higher-than-necessary regret in these settings and do not leverage information on the rate of change. We study a non-stationary two-armed bandits problem where we assume that an arm's mean reward is a $\beta$-H\"older function over (normalized) time, meaning it is $(\beta-1)$-times Lipschitz-continuously differentiable. We show the first separation between the smooth and non-smooth regimes by presenting a policy with $\tilde O(T^{3/5})$ regret for $\beta=2$. We complement this result by an $\Omg(T^{(\beta+1)/(2\beta+1)})$ lower bound for any integer $\beta\ge 1$, which matches our upper bound for $\beta=2$., Comment: Accepted by ICML 2023

Published
2023

16. Cost-aware Defense for Parallel Server Systems against Reliability and Security Failures

Author

Xie, Qian, Wang, Jiayi, and Jin, Li

Subjects
Electrical Engineering and Systems Science - Systems and Control, Computer Science - Computer Science and Game Theory, Mathematics - Optimization and Control
Abstract

Parallel server systems in transportation, manufacturing, and computing heavily rely on dynamic routing using connected cyber components for computation and communication. Yet, these components remain vulnerable to random malfunctions and malicious attacks, motivating the need for fault-tolerant dynamic routing that are both traffic-stabilizing and cost-efficient. In this paper, we consider a parallel server system with dynamic routing subject to reliability and stability failures. For the reliability setting, we consider an infinite-horizon Markov decision process where the system operator strategically activates protection mechanism upon each job arrival based on traffic state observations. We prove an optimal deterministic threshold protecting policy exists based on dynamic programming recursion of the HJB equation. For the security setting, we extend the model to an infinite-horizon stochastic game where the attacker strategically manipulates routing assignment. We show that both players follow a threshold strategy at every Markov perfect equilibrium. For both failure settings, we also analyze the stability of the traffic queues under control. Finally, we develop approximate dynamic programming algorithms to compute the optimal/equilibrium policies, supplemented with numerical examples and experiments for validation and illustration., Comment: Major Revision in Automatica

Published
2023

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