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Stochastic stabilization of multi-degree-of-freedom nonlinear random-time-delay controlled systems

INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL 2023年第3期33卷 2288-2303页

作者： Hu, Rongchun Lu, Xiang Zhang, Dongxu Gu, Xudong Northwestern Polytech Univ MIIT Key Lab Dynam & Control Complex Syst Dept Engn Mech Xian Peoples R China Northwestern Polytech Univ MIIT Key Lab Dynam & Control Complex Syst Dept Engn Mech Xian 710129 Peoples R China

The random-time-delay (RTD) occurs inevitably in feedback control, caused by the utilization of a multi-user network with random demands. This paper is devoted to the stochastic stabilization of multi-degree-of-freedom (MDOF) nonlinear RTD controlled systems. Firstly, a two-step approximated method is proposed to deal with RTD: by modeling the RTD as a Markov jump process, the RTD control is formulated as the one with discrete jump varying delay;utilizing the randomly periodic characteristic, the Markov jump delay is taken out of the control as a parameter. The stochastic averaging principle is applied to generate a less-dimensional averaged governing equation of system's energies. Secondly, the dynamical programming principle is applied to the ergodic control problem of the average systems with an undetermined cost function, which is determined by the demand of stabilizing the averaged systems, then the optimal control law is deduced. A largest Lyapunov exponent is introduced to the averaged systems to evaluate the asymptotic stability with probability one. Finally, an example is worked out to demonstrate the application and effectiveness of the proposed method.

关键词： largest Lyapunov exponent nonlinear systems random-time-delay stochastic stabilization

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Strider: Signal Value Transition-Guided Defect Repair for HDL Programming Assignments

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IEEE TRANSACTIONS ON COMPUTER-AIDED DESIGN OF INTEGRATED CIRCUITS AND systEMS 2024年第5期43卷 1594-1607页

作者： Yang, Deheng He, Jiayu Mao, Xiaoguang Li, Tun Lei, Yan Yi, Xin Wu, Jiang Natl Univ Def Technol Coll Comp Key Lab Software Engn Complex Syst Changsha 410073 Peoples R China Natl Univ Def Technol Coll Comp Changsha 410073 Peoples R China Chongqing Univ Sch Big Data & Software Engn Chongqing 401331 Peoples R China

Hardware description languages (HDLs) are pivotal for the development of hardware designs. The programming courses for HDLs are also popular in both universities and online course platforms. Similar to programming assignments of software languages (SLs), these of HDLs also actively call for automated program repair (APR) techniques to provide personalized feedback for students. However, the research of APR techniques targeting HDL programming assignments is still in an early stage. Due to the significantly different programming mechanism of HDLs from SLs, the only APR technique (i.e., CirFix) targeting HDL programming assignments contributes a customized repair pipeline. However, the fundamental challenges in the design of HDL-oriented fault localization and patch generation still remain unresolved. In this work, we propose a signal value transition-guided defect repair technique named Strider by capturing the intrinsic features of HDLs. This technique consists of a time-aware dynamic defect localization approach to precisely localize defects, and a signal value transition-guided patch synthesis approach to effectively generate fixes. We further construct a dataset of 57 real defects from HDL programming assignments for tool evaluation. The evaluation reveals the overfitting issue of the pioneering tool CirFix and the significant improvement of Strider over CirFix in terms of both effectiveness and efficiency. In particular, Strider is more effective by correctly fixing 2.3x as many defects as CirFix in the real defect dataset, and is 23x more efficient by generating a correct fix within 5 min on average in the synthetic defect dataset, while CirFix takes around 2 h on average.

关键词： Programming Hardware design languages Maintenance engineering Hardware software Location awareness Timing Automated program repair (APR) fault localization hardware description languages (HDLs) programming assignments

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Adaptive Tracking Control for Stochastic Nonlinear Time-Delay systems With Full-State Constraints and Input Saturation Based on Multi-Dimensional Taylor Network

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INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING 2025年

作者： Zheng, Xiao-Yi Yan, Hong-Sen Southeast Univ Sch Automat Nanjing Peoples R China Minist Educ Key Lab Measurement & Control Complex Syst Engn Nanjing Peoples R China

For stochastic nonlinear time-delay systems with full-state constraints and input saturation, the existing control methods cannot be directly applied. To solve the control problem, an adaptive tracking control scheme is proposed here. The barrier Lyapunov function (BLF) and Lyapunov-Krasovskii functional (LKF) are combined in a unified framework. The former is to prevent the violation of state constraints and the latter is to address the impact of time delay. A suitable auxiliary system with the same order as the considered system is constructed to compensate for input saturation. Moreover, the multi-dimensional Taylor network (MTN) is introduced to estimate unknown nonlinear functions in the process of controller design. With the help of the Lyapunov stability theorem and the backstepping technique, an adaptive MTN tracking controller is developed to ensure that all the closed-loop signals remain bounded in probability and that the system state constraints are never violated while the output signal tracks the reference one successfully. Simulation examples with three types of reference signals (y(d) = 0.5 sin (2t), y(d) = 0.9 and the square reference signal) are provided to verify the validity of the designed control approach.

关键词： adaptive tracking control auxiliary system full-state constraints input saturation multi-dimensional Taylor network stochastic nonlinear time-delay systems

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SeSICL: Semantic and Structural Integrated Contrastive Learning for Knowledge Graph Error Detection

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IEEE ACCESS 2024年 12卷 56088-56096页

作者： Liu, Xingyu Tang, Jielong Li, Mengyang Han, Junmei Xiao, Gang Jiang, Jianchun Chinese Acad Sci Inst Software State Key Lab Intelligent Game Beijing 100190 Peoples R China Sun Yat Sen Univ Sch Artificial Intelligence Guangzhou 510330 Peoples R China Chinese Acad Sci Inst Software Integrat Innovat Ctr Beijing 100190 Peoples R China Syst Engn Inst Syst Res Dept Natl Key Lab Complex Syst Simulat AMS Beijing 100192 Peoples R China

As knowledge graphs (KGs) become more widely used in various applications, error detection for KGs has received more attention, which can reduce quality issues such as errors and inconsistencies. With the development of representation learning, embedding-based methods have significantly improved error detection performance. The recent error detection algorithm uses KG structural embedding loss and constructs a reasonable score function, ranking the confidence scores for each triplet. However, these methods ignore the factual semantics of the triplet itself, which primarily exist in the entities and relations descriptions text. Therefore, we propose Semantic and Structural Integrated Contrastive Learning(SeSICL) to simultaneously capture graph structural patterns and deep semantic features from descriptions text. Our method is based on contrastive learning without data augmentation, which utilizes encoder perturbations to generate contrasting views, making SeSICL highly suitable for complex error detection tasks and robust against real-world noise. We evaluate SeSICL on three baseline datasets with abnormal data and fluctuations. SeSICL outperforms the previous state-of-the-art methods, demonstrating our method's performance and robustness in more complex scenarios.

关键词： Knowledge graph error detection semantic embedding structural embedding contrastive learning

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Effect of methanol on the pyrolysis behaviour of kerogen by ReaxFF molecular dynamics simulations

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MOLECULAR SIMULATION 2024年第1期50卷 43-54页

作者： Yu, Mingyue Zhan, Jin-Hui Li, Xiang He, Wen Liu, Xiaoxing Shenyang Univ Chem Technol Coll Chem Technol Shenyang Peoples R China Chinese Acad Sci Inst Proc Engn State Key Lab Multiphase Complex Syst Beijing Peoples R China Chinese Acad Sci Inst Proc Engn State Key Lab Multiphase Complex Syst Beijing 100190 Peoples R China

A series of molecular dynamics simulations were performed using the ReaxFF reactive force field to investigate the pyrolysis of Longkou oil shale kerogen in the presence of methanol. The roles of methanol in kerogen pyrolysis were deeply explored to reveal the microscopic mechanism of methanolysis by analyzing the distribution of products, the consumption of methanol, and the formation processes of typical products at different temperatures. The results demonstrate that the yield of shale oil in the presence of methanol is consistently higher than that of kerogen direct pyrolysis at the same temperature, which is consistent with the trend of oil yield with temperature reported by previous methanolysis experiments. Methanol supplies a large number of small radicals under the pyrolysis condition, which can facilitate the breakage of weak bonds and take part in the formation of products through combining with the radical fragments generated by the pyrolysis of kerogen. This study will provide theoretical guidance for understanding the methanolysis process of oil shale.

关键词： Kerogen methanolysis mechanism molecular dynamics ReaxFF

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Static analysis of linear absolute value equalities among variables of a program

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SCIENCE OF COMPUTER PROGRAMMING 2023年 225卷

作者： Chen, Liqian Wei, Dengping Yin, Banghu Wang, Ji Natl Univ Def Technol Changsha 410073 Peoples R China Hunan Key Lab Software Engn Complex Syst Changsha 410073 Peoples R China State Key Lab High Performance Comp Changsha 410073 Peoples R China

The classic linear (technically, affine) equality abstract domain, which can infer linear equality relations among variables of a program automatically, is one of the earliest and fundamental abstract domains. However, it cannot express non-convex properties that appear naturally due to the inherent disjunctive behaviors in programs. In this paper, we introduce a new abstract domain, namely the abstract domain of linear absolute value equalities (AVE), which generalizes the linear equality abstract domain with absolute value terms of variables. More clearly, we leverage the absolute value function to design the new abstract domain for discovering linear equality relations among values and absolute values of program variables. Moreover, since linear absolute value equalities can only express limited form of inequalities while programs often involve various inequalities, to help the AVE domain, we propose a so-called signed interval abstract domain as an extension of the classic interval abstract domain. The key idea is to use two intervals to track respectively the positive part and the negative part of the interval range for each variable. On this basis, we propose to combine the two new abstract domains to improve precision of each other during analysis. Experimental results are encouraging: In practice, the AVE abstract domain (together with the signed interval abstract domain) can find interesting piece-wise linear invariants that are non-convex and out of the expressiveness of the linear equality domain.(c) 2022 Elsevier B.V. All rights reserved.

关键词： Abstract interpretation Abstract domain Absolute value Invariant Interval

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Lamb waves manipulation by piezoelectric metasurface with tunable diffraction orders

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FRONTIERS IN PHYSICS 2023年 10卷

作者： Shao, Shixuan Chen, Jiyue Xia, Rongyu Li, Zheng Peking Univ Dept Mech & Engn Sci State Key Lab Turbulence & Complex Syst Beijing Peoples R China

In this paper, a piezoelectric metasurface is proposed to manipulate the anti-symmetric mode Lamb wave by altering the diffraction order. The metasurface attached to a host plate is symmetrically arranged by out-of-plane polarized piezoelectric patches connected with synthetic inductance circuits. Without changing the physical configuration, the transmitted phase of the anti-symmetric mode Lamb wave can be shifted arbitrarily in 0 similar to 2 pi range by the metasurface. Furthermore, the relationship between the phase gradient and diffraction order is investigated, and different orders of diffraction waves can be obtained by adjusting the shunting inductance circuits. The symmetric transmission and asymmetric transmission from a couple of axis symmetric incident waves can be realized by utilizing +1st-order and -1st-order diffraction. Moreover, omnidirectional wave reflection and wave trapping in channelized waveguides can also be realized by utilizing the 0th-order diffraction. The results indicate that the proposed piezoelectric metasurface has great potentials in manipulating guided waves with a large incident angle and isolating wave propagation.

关键词： metasurface Lamb wave diffraction piezoelectricity metamaterials anomalous refraction

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system log isolation for containers

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FRONTIERS OF COMPUTER SCIENCE 2025年第5期19卷 1-11页

作者： Wang, Kun Wu, Song Cui, Yanxiang Huang, Zhuo Fan, Hao Jin, Hai Huazhong Univ Sci & Technol Natl Engn Res Ctr Big Data Technol & Syst Sch Comp Sci & Technol Serv Comp Technol & Syst Lab Wuhan 430074 Peoples R China Natl Univ Def Technol State Key Lab Complex & Crit Software Environm Wuhan 430019 Hubei Peoples R China

Container-based virtualization is increasingly popular in cloud computing due to its efficiency and flexibility. Isolation is a fundamental property of containers and weak isolation could cause significant performance degradation and security vulnerability. However, existing works have almost not discussed the isolation problems of system log which is critical for monitoring and maintenance of containerized applications. In this paper, we present a detailed isolation analysis of system log in current container environment. First, we find several system log isolation problems which can cause significant impacts on system usability, security, and efficiency. For example, system log accidentally exposes information of host and co-resident containers to one container, causing information leakage. Second, we reveal that the root cause of these isolation problems is that containers share the global log configuration, the same log storage, and the global log view. To address these problems, we design and implement a system named private logs (POGs). POGs provides each container with its own log configuration and stores logs individually for each container, avoiding log configuration and storage sharing, respectively. In addition, POGs enables private log view to help distinguish which container the logs belong to. The experimental results show that POGs can effectively enhance system log isolation for containers with negligible performance overhead.

关键词： container isolation system log cgroup namespace cloud computing

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Sub-preferential rotational wave beaming in structurally rhombus re-entrant honeycombs

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INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES 2024年 290卷

作者： Zhu, Zhiwei Deng, Zichen Shijiazhuang Tiedao Univ State Key Lab Mech Behav & Syst Safety Traff Engn Shijiazhuang 050043 Peoples R China Northwestern Polytech Univ MIIT Key Lab Dynam & Control Complex Syst Xian 710072 Peoples R China

Rotational waves frequently manifest in micro-structured materials and are often coupled with classical shear or longitudinal wave modes. In this study, a distinctive isolated optical branch, exhibiting very high polarization index related to joint rotation motion, is found in dispersion diagram of elastic wave propagation in structurally rhombus re-entrant honeycomb (SSRH). Through an analysis of group velocity, we further explore the wave beaming of the rotational wave propagation within the SRRH, and intriguingly, observe the emergence of subpreferential wave beaming occurring along the short diagonal directions. This dynamic anisotropic phenomenon stems from the intricate interplay between wave frequency and structural topology. To elucidate the underlying dynamic anisotropy of rotational waves, we propose a simple rigid-spring model and derive a modulation function that precisely captures the intricate frequency-structure coupling behavior. The obtained modulation function unveils the formation of sub-preferential directions of the rotational wave within the SRRH.

关键词： Lattice materials Frequency -structure coupling Rotational wave mode Wave beaming

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Data-driven optimization of nose profiles for water entry impact load reduction

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OCEAN ENGINEERING 2025年 315卷

作者： Lv, Kai Lin, Enfan Liu, Yongze Chen, Zongbao Wang, Yexian He, Ming Yan, Jiale Lv, Pengyu Yang, Yantao Li, Hongyuan Duan, Huiling Peking Univ Coll Engn Dept Mech & Engn Sci State Key Lab Turbulence & Complex SystBIC ESAT Beijing 100871 Peoples R China Laoshan Lab Qingdao 266237 Peoples R China

The prediction and reduction of impact loads during water entry are critical in various engineering applications, such as ship slamming and seaplane landings. Traditional methods, including theoretical models, computational fluid dynamics (CFD), and experimental approaches, often suffer from limited applicability, lengthy processing times, and high costs. To address these challenges, this study explores the use of Deep Neural Networks (DNNs) for predicting peak impact loads during the oblique water entry of cylinders with different nose profiles. Optimized Latin Hypercube Sampling (OLHS) and Sobol sequences are employed to generate dataset inputs from a 7dimensional parameter space that governs impact dynamics. These inputs are then fed into OpenFOAM solvers to compute the peak impact accelerations, serving as dataset outputs for training and testing the DNN. Experiments are conducted to validate the numerical method, confirming that the resulting dataset outputs can be considered as ground truth. With Bayesian hyperparameter optimization, the well-trained DNN model demonstrates reliable accuracy in predicting peak axial and normal accelerations. Further, this study integrates the DNN model with the Non-dominated Sorting Genetic Algorithm II (NSGA-II) to optimize the nose profiles, resulting in a maximum weighted reduction of 48% in the combined axial and normal accelerations.

关键词： Water entry Impact load Deep neural networks Artificial intelligence Nose profile optimization

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