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Accurate segmentation of lesions in lung CT images remains challenging due to blurred boundaries, small lesion sizes, and the scarcity of annotated data. To address these issues, this paper proposes a semi-supervised contrastive learning framework with a novel multiple attention UNet (MA-UNet) for lung CT image segmentation. The MA-UNet integrates a dual-attention module (DAM) and attention gates (AGs) to enhance spatial-channel feature refinement and boundary sensitivity. The DAM captures global context and channel-wise dependencies, while the AG emphasizes lesion-related features. Furthermore, residual blocks are used to improve gradient propagation and computational efficiency. To overcome limited annotations, we propose a contrastive learning framework that can fully utilize both labeled and unlabeled data to improve segmentation accuracy. To verify the validity of the methods and parameters design in this paper, we systematically carry out multiple ablation experiments. The experimental results show that the Dice, MIoU and Recall scores of MA-UNet based on comparative learning with only 1/2 ratio of labeled data are 78.41%, 88.78% and 91.79%, respectively, which are close to its supervised segmentation model, which effectively overcomes the problem of lack of labeled data.
Keyword ：
Attention mechanism Attention mechanism Contrastive learning Contrastive learning Lung CT image Lung CT image Semi-supervised segmentation Semi-supervised segmentation
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| GB/T 7714 | Qi, Yiwen , Yao, Caibin , Chen, Hao et al. Semi-supervised segmentation of lung CT images based on contrastive learning [J]. | SIGNAL IMAGE AND VIDEO PROCESSING , 2025 , 19 (7) . |
| MLA | Qi, Yiwen et al. "Semi-supervised segmentation of lung CT images based on contrastive learning" . | SIGNAL IMAGE AND VIDEO PROCESSING 19 . 7 (2025) . |
| APA | Qi, Yiwen , Yao, Caibin , Chen, Hao , Wang, Xufei . Semi-supervised segmentation of lung CT images based on contrastive learning . | SIGNAL IMAGE AND VIDEO PROCESSING , 2025 , 19 (7) . |
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This paper proposes an optimal output synchronization control method for heterogeneous multi -agent systems (HMASs) under a performance -dependent switching topology and DoS attacks. First, local and global switched performance index functions (SPIF) and SPIF-dependent topology switching law are proposed, respectively, thus, the control performance and topology quality can be quantitatively expressed. Second, an adaptive dynamic programming (ADP) algorithm with mode switching is proposed, aimed at dealing with the difficult Hamilton-Jacobi- Bellman equation, as well as the analytical complexity caused by the switching dynamics. The convergence of the switched ADP algorithm is proven to ensure its correct implementation. Then, for different topologies, multi -mode Actor-Critic neural networks (NNs) are built for each agent to calculate optimized control policies and SPIF, respectively. Furthermore, an NNbased state compensation mechanism is designed to expand the applicability of the designed switched ADP algorithm when the leader's output transmission is unreliable. Finally, the results of numerical examples confirm that the proposed method is feasible.
Keyword ：
DoS attacks DoS attacks Heterogeneous multi-agent systems Heterogeneous multi-agent systems Switched adaptive dynamic programming Switched adaptive dynamic programming Switching topology Switching topology
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| GB/T 7714 | Qi, Yiwen , Wang, Yunlong , Geng, Honglin et al. Optimal synchronization for multi-agent systems: A performance-dependent switching topology [J]. | JOURNAL OF THE FRANKLIN INSTITUTE-ENGINEERING AND APPLIED MATHEMATICS , 2024 , 361 (6) . |
| MLA | Qi, Yiwen et al. "Optimal synchronization for multi-agent systems: A performance-dependent switching topology" . | JOURNAL OF THE FRANKLIN INSTITUTE-ENGINEERING AND APPLIED MATHEMATICS 361 . 6 (2024) . |
| APA | Qi, Yiwen , Wang, Yunlong , Geng, Honglin , Xing, Ning , Zheng, Zonghua , Li, He . Optimal synchronization for multi-agent systems: A performance-dependent switching topology . | JOURNAL OF THE FRANKLIN INSTITUTE-ENGINEERING AND APPLIED MATHEMATICS , 2024 , 361 (6) . |
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This paper explores event-triggered model predictive control (MPC) for constrained switched systems, incorporating a buffer-based anti-attack (BBAA) approach to ensure network security. Since the system state is unknown and disturbed, an observer-based $ H_{\infty } $ H infinity MPC approach is used to estimate the system state and suppress disturbance. Furthermore, the estimated state and control input can be optimised by minimising the performance function. Considering that the system state is subject to denial of service (DoS) attacks in the feedback channel, the BBAA approach is used to reconstruct the estimated state, thereby reducing the impact of attacks on system performance. To improve the utilisation of network resources, a set of event-triggering mechanisms (ETMs) is used. In addition, a set of matrix inequality conditions is given to constrain the gains of controllers and observers. Then, the system $ H_{\infty } $ H infinity performance is demonstrated by applying the average dwell time (ADT) and the Lyapunov function method, and the complex coupling between model switching, DoS attacks and event-triggering is analysed. Simulation results validate the effectiveness of the proposed approach.
Keyword ：
buffer-based anti-attack approach buffer-based anti-attack approach DoS attacks DoS attacks model predictive control model predictive control Switched systems Switched systems
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| GB/T 7714 | Lv, Yanbo , Qi, Yiwen , Guo, Shitong et al. Enhancing network security in constrained switched systems: event-triggered MPC with a buffer-based anti-attack approach [J]. | INTERNATIONAL JOURNAL OF SYSTEMS SCIENCE , 2024 , 55 (14) : 2963-2979 . |
| MLA | Lv, Yanbo et al. "Enhancing network security in constrained switched systems: event-triggered MPC with a buffer-based anti-attack approach" . | INTERNATIONAL JOURNAL OF SYSTEMS SCIENCE 55 . 14 (2024) : 2963-2979 . |
| APA | Lv, Yanbo , Qi, Yiwen , Guo, Shitong , Qu, Ziyu , Li, He . Enhancing network security in constrained switched systems: event-triggered MPC with a buffer-based anti-attack approach . | INTERNATIONAL JOURNAL OF SYSTEMS SCIENCE , 2024 , 55 (14) , 2963-2979 . |
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This paper explores online learning model predictive control (MPC) for switched systems with stable terminal constraints. In order to reduce the computational burden, we decompose the infinite horizon MPC into n finite horizons, and adopt adaptive dynamic programming (ADP) to assist MPC in online solving the optimal control problem in each finite horizon. Further, we use a set of stable terminal constraints to ensure both the convergence of online learning MPC in each finite horizon and the connection of adjacent finite horizons. In addition, in order to ensure the uniform ultimate boundedness (UUB) of the triggered switched systems, on the one hand, a novel performance dependent mixed switching law (PD-MSL) is proposed to both avoid frequent switching and take advantage of performance dependent decision-making; on the other hand, an analytical framework of the coupling between mode switching and event-triggering is proposed. Finally, the validity of the presented approach is demonstrated through simulations.
Keyword ：
Online learning MPC Online learning MPC Performance dependent mixed switching law Performance dependent mixed switching law Stable terminal constraints Stable terminal constraints Switched systems Switched systems
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| GB/T 7714 | Qi, Yiwen , Lv, Yanbo , Qu, Ziyu et al. Online learning MPC for switched systems with performance dependent mixed switching law [J]. | JOURNAL OF THE FRANKLIN INSTITUTE-ENGINEERING AND APPLIED MATHEMATICS , 2024 , 361 (15) . |
| MLA | Qi, Yiwen et al. "Online learning MPC for switched systems with performance dependent mixed switching law" . | JOURNAL OF THE FRANKLIN INSTITUTE-ENGINEERING AND APPLIED MATHEMATICS 361 . 15 (2024) . |
| APA | Qi, Yiwen , Lv, Yanbo , Qu, Ziyu , Guo, Shitong . Online learning MPC for switched systems with performance dependent mixed switching law . | JOURNAL OF THE FRANKLIN INSTITUTE-ENGINEERING AND APPLIED MATHEMATICS , 2024 , 361 (15) . |
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In this article, the full differential privacy-preserving problem for switched LPV systems is concerned. The security of a control system is the ability to avoid intentional sabotage or accidental interference affecting its normal operation. For switched LPV systems, it contains both internal (scheduling variable and switching signal) and external (system output) information that needs to be protected, we adopt differential privacy to achieve its full privacy preserving. The resulting challenges are: 1) privacy design for three types of system signals and 2) dual asynchronization analysis under triple privacy noise. Accordingly, three differential privacy definitions and Laplace (resp. uniform) noise design methods are presented. Sufficient conditions for H-infinity control design with dual asynchronization analysis are given. Finally, simulation results verify the effectiveness of the proposed method.
Keyword ：
Databases Databases Data privacy Data privacy Differential privacy Differential privacy Dual asynchronization Dual asynchronization Dynamical systems Dynamical systems full differential privacy preserving full differential privacy preserving H-infinity control H-infinity control Privacy Privacy Security Security switched LPV systems switched LPV systems Switches Switches
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| GB/T 7714 | Qi, Yiwen , Tang, Yiwen , Kawano, Yu . Full Differential Privacy Preserving for Switched LPV Systems [J]. | IEEE TRANSACTIONS ON SYSTEMS MAN CYBERNETICS-SYSTEMS , 2024 , 54 (5) : 3153-3163 . |
| MLA | Qi, Yiwen et al. "Full Differential Privacy Preserving for Switched LPV Systems" . | IEEE TRANSACTIONS ON SYSTEMS MAN CYBERNETICS-SYSTEMS 54 . 5 (2024) : 3153-3163 . |
| APA | Qi, Yiwen , Tang, Yiwen , Kawano, Yu . Full Differential Privacy Preserving for Switched LPV Systems . | IEEE TRANSACTIONS ON SYSTEMS MAN CYBERNETICS-SYSTEMS , 2024 , 54 (5) , 3153-3163 . |
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This paper concerns fault detection filter design for switched Takagi-Sugeno (T-S) fuzzy systems against deception attacks. A fuzzy fault detection filter with attacked input signal is presented to detect system faults. Switched event-triggering schemes are adopted to efficiently utilize limited network communication bandwidth resources. Moreover, the filter adopts nonsynchronous premise variables with the system to handle communication delays caused by event-triggering schemes and network transmission. Then, the switched fuzzy residual systems are developed by utilizing a model transformation technique. Furthermore, by using piecewise Lyapunov functional method and persistent dwell time (PDT) technique, the resulting criterion provides sufficient conditions to ensure that switched fuzzy residual systems under deception attacks are mean-square exponentially (MSE) stable with an H1 performance. Accordingly, the conditions for the co-design of fuzzy filter and event-triggering schemes are given. Finally, the effectiveness of the design of the fault detection filter is verified by a numerical simulation and an air path of the TCSI engine simulation.
Keyword ：
Deception attacks Deception attacks Event-triggering (ET) schemes Event-triggering (ET) schemes Fault detection filter Fault detection filter PDT PDT Switched T-S fuzzy (STSF) systems Switched T-S fuzzy (STSF) systems
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| GB/T 7714 | Yao, Zhaohui , Tang, Yiwen , Yuan, Shuo et al. Filtering for PDT Switched T-S Fuzzy Systems With Attacks and Disorders: A TCSI Engine Fault Detection [J]. | INTERNATIONAL JOURNAL OF FUZZY SYSTEMS , 2023 , 25 (4) : 1429-1443 . |
| MLA | Yao, Zhaohui et al. "Filtering for PDT Switched T-S Fuzzy Systems With Attacks and Disorders: A TCSI Engine Fault Detection" . | INTERNATIONAL JOURNAL OF FUZZY SYSTEMS 25 . 4 (2023) : 1429-1443 . |
| APA | Yao, Zhaohui , Tang, Yiwen , Yuan, Shuo , Qi, Yiwen . Filtering for PDT Switched T-S Fuzzy Systems With Attacks and Disorders: A TCSI Engine Fault Detection . | INTERNATIONAL JOURNAL OF FUZZY SYSTEMS , 2023 , 25 (4) , 1429-1443 . |
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Stability is fundamental to ensure the operation of control system, but optimality is the ultimate goal to achieve the maximum performance. This paper investigates an eventtriggered pinning optimal consensus control for switched multi-agent system (SMAS) via a switched adaptive dynamic programming (ADP) method. The technical contribution mainly lies in two aspects. On the one hand, in order to optimize the control performance and ensure the consensus, the switched local value function (SLVF) and the minimumerror switching law are constructed. Based on SLVF, an algorithm of switched ADP policy iteration is proposed, and its convergence and optimality are proved. On the other hand, considering that it is impractical to install a controller for each agent in reality, a pinning strategy is developed to guide the setting of the ADP controller, which can reduce the waste of control resources. A new condition is constructed to determine the minimum number of controlled vertices of the SMAS. Lastly, a numerical example is given to verify the effectiveness of the proposed method. (c) 2022 Elsevier Ltd. All rights reserved.
Keyword ：
Adaptive dynamic programming Adaptive dynamic programming Control constraint Control constraint Pinning control Pinning control Switched multi-agent system Switched multi-agent system
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| GB/T 7714 | Qi, Yiwen , Geng, Honglin . Pinning consensus control for switched multi-agent systems: A switched adaptive dynamic programming method [J]. | NONLINEAR ANALYSIS-HYBRID SYSTEMS , 2023 , 48 . |
| MLA | Qi, Yiwen et al. "Pinning consensus control for switched multi-agent systems: A switched adaptive dynamic programming method" . | NONLINEAR ANALYSIS-HYBRID SYSTEMS 48 (2023) . |
| APA | Qi, Yiwen , Geng, Honglin . Pinning consensus control for switched multi-agent systems: A switched adaptive dynamic programming method . | NONLINEAR ANALYSIS-HYBRID SYSTEMS , 2023 , 48 . |
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A high-precision variable-thrust control method based on real-time measurement of pintle displacement and closed-loop feedback control is proposed to solve the technical problems of deep throttling variable-thrust regulation and control of pintle liquid rocket engines (LRE). By optimizing the system structure and control parameters, the closed-loop control of displacement with high precision and a fast response under a wide range of variable thrust can be realized, and thus the large-range, fast-response, and high-precision control of the chamber pressure, equivalent to thrust, can be indirectly realized. The chamber pressure response time is not more than 0.3 s, the overshoot is not more than +/- 3%, and the pulsation amplitude is not more than +/- 5%, which can meet the technical requirements of the large-range thrust adjustment and control of variable-thrust LRE of reusable launch rockets. The proposed variable-thrust LRE thrust control system is simple, reliable, and easy to use and maintain, which solves the problem of the large range, high precision, and fast response of thrust adjustment and control. The proposed system can provide important technical support for carrier rocket recycling and launch cost reduction. This is the first time a closed-loop control method of displacement of an integrated gas generator/flow regulator to achieve a 5:1 large-range continuous-variable-thrust control for the LRE of a reusable launch rocket has been proposed.
Keyword ：
displacement closed-loop control displacement closed-loop control gas generator gas generator integrated flow regulator integrated flow regulator reusable launch rocket reusable launch rocket thrust control thrust control variable-thrust liquid rocket engine variable-thrust liquid rocket engine
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| GB/T 7714 | Yao, Zhaohui , Qi, Yiwen , Bao, Wen et al. Thrust Control Method and Technology of Variable-Thrust Liquid Engine for Reusable Launch Rocket [J]. | AEROSPACE , 2023 , 10 (1) . |
| MLA | Yao, Zhaohui et al. "Thrust Control Method and Technology of Variable-Thrust Liquid Engine for Reusable Launch Rocket" . | AEROSPACE 10 . 1 (2023) . |
| APA | Yao, Zhaohui , Qi, Yiwen , Bao, Wen , Zhang, Tianhong . Thrust Control Method and Technology of Variable-Thrust Liquid Engine for Reusable Launch Rocket . | AEROSPACE , 2023 , 10 (1) . |
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Uncertainty and disturbance are always the first issues to deal with in any networked system. Considering these factors, the active disturbance rejection control (ADRC) for networked switched systems (NSSs) with decentralized event-triggered communication was investigated in this study. This is the first time a comprehensive analysis and synthesis method for the ADRC of NSSs has been proposed. The technical contribution is mainly divided into two categories. On the one hand, a novel parameter-dependent switching constraint is proposed, which solves the problem of ADRC-based switching law construction and settles the complex coupling between switching, event-triggering, and ADRC components. On the other hand, triggering the output of linear extended state observer (LESO) rather than its input can result in a more accurate estimation, while reasonably configuring network resources. Accordingly, a new tight bound of the high gain adjustment parameter of the observer was obtained. In addition, the stability analysis and state convergence region calculations for switched ADRC systems are given. Finally, the effectiveness of the proposal is demonstrated by simulation.
Keyword ：
Active disturbance rejection control (ADRC) Active disturbance rejection control (ADRC) ADRC-based switching law ADRC-based switching law linear extended state observer (LESO)-based event-triggering scheme linear extended state observer (LESO)-based event-triggering scheme networked switched systems (NSSs) networked switched systems (NSSs)
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| GB/T 7714 | Qi, Yiwen , Zhang, Simeng , Ahn, Choon Ki . Active Disturbance Rejection Control for Networked Switched Nonlinear Systems With Decentralized Event-Triggered Communication [J]. | IEEE TRANSACTIONS ON SYSTEMS MAN CYBERNETICS-SYSTEMS , 2023 , 53 (6) : 3553-3565 . |
| MLA | Qi, Yiwen et al. "Active Disturbance Rejection Control for Networked Switched Nonlinear Systems With Decentralized Event-Triggered Communication" . | IEEE TRANSACTIONS ON SYSTEMS MAN CYBERNETICS-SYSTEMS 53 . 6 (2023) : 3553-3565 . |
| APA | Qi, Yiwen , Zhang, Simeng , Ahn, Choon Ki . Active Disturbance Rejection Control for Networked Switched Nonlinear Systems With Decentralized Event-Triggered Communication . | IEEE TRANSACTIONS ON SYSTEMS MAN CYBERNETICS-SYSTEMS , 2023 , 53 (6) , 3553-3565 . |
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This paper studies model predictive control (MPC) with control barrier function to solve the stability and safety problems of switched systems subject to input and state constraints. Considering that the system state is unmeasurable and disturbed, an observer-based MPC $ H_\infty $ H infinity method is adopted to estimate the system state and suppress disturbances. A cost function is designed to optimise the state and control input of switched systems by minimising its upper bound, and the optimisation problem is further transformed into a feasibility problem. Moreover, a control barrier function is introduced to constrain the controller gains, which ensures that the initial state of switched systems converges to the steady state without entering the specified unsafe region. Furthermore, a set of matrix inequality conditions is given to express the input and state constraints. Then, the Lyapunov function and average dwell time (ADT) approach are used to obtain sufficient conditions for the asymptotic stability of switched systems. Finally, two simulation examples are given to verify the effectiveness of the proposed method.
Keyword ：
control barrier function control barrier function input and state constraints input and state constraints model predictive control model predictive control Switched systems Switched systems
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| GB/T 7714 | Qi, Yiwen , Guo, Shitong , Tang, Yiwen et al. Safety MPC of constrained switched systems with control barrier function [J]. | INTERNATIONAL JOURNAL OF SYSTEMS SCIENCE , 2023 , 55 (1) : 87-101 . |
| MLA | Qi, Yiwen et al. "Safety MPC of constrained switched systems with control barrier function" . | INTERNATIONAL JOURNAL OF SYSTEMS SCIENCE 55 . 1 (2023) : 87-101 . |
| APA | Qi, Yiwen , Guo, Shitong , Tang, Yiwen , Geng, Honglin , Huang, Jie . Safety MPC of constrained switched systems with control barrier function . | INTERNATIONAL JOURNAL OF SYSTEMS SCIENCE , 2023 , 55 (1) , 87-101 . |
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