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On convergence of covariance matrix of empirical Bayes hyper-parameter estimator

Control Theory and technology 2024年第2期22卷 149-162页

作者： Yue Ju Biqiang Mu Tianshi Chen School of Data Science and Shenzhen Research Institute of Big Data The Chinese University of Hong KongShenzhenShenzhen518172GuangdongChina Division of Decision and Control Systems School of Electrical Engineering and Computer ScienceKTH Royal Institute of Technology10044StockholmSweden Key Laboratory of Systems and Control Institute of Systems ScienceAcademy of Mathematics and System ScienceChinese Academy of SciencesBeijing100190China

Regularized system identification has become the research frontier of system identification in the past *** related core subject is to study the convergence properties of various hyper-parameter estimators as the sample size goes to *** this paper,we consider one commonly used hyper-parameter estimator,the empirical Bayes(EB).Its convergence in distribution has been studied,and the explicit expression of the covariance matrix of its limiting distribution has been ***,what we are truly interested in are factors contained in the covariance matrix of the EB hyper-parameter estimator,and then,the convergence of its covariance matrix to that of its limiting distribution is *** general,the convergence in distribution of a sequence of random variables does not necessarily guarantee the convergence of its covariance ***,the derivation of such convergence is a necessary complement to our theoretical analysis about factors that influence the convergence properties of the EB hyper-parameter *** this paper,we consider the regularized finite impulse response(FIR)model estimation with deterministic inputs,and show that the covariance matrix of the EB hyper-parameter estimator converges to that of its limiting ***,we run numerical simulations to demonstrate the efficacy of ourtheoretical results.

关键词： Regularized system identification Hyper-parameter estimator Empirical Bayes Convergence of covariance matrix

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Wavelet-Based Hybrid Ensemble Forecasting for Accurate Web Traffic Prediction 1

Wavelet-Based Hybrid Ensemble Forecasting for Accurate Web T...

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1st International Conference on Innovations in Communications, Electrical and Computer engineering, ICICEC 2024

作者： Manoj Kumar, M.V. Puneetha, B.H. Prashanth, B.S. Sneha, H.R. Patil, N.S. Ranjana, B.J. Nitte Meenakshi Institute of Technology Department of Information Science & Engineering Karnataka Bangalore560064 India Bapuji Institute of Engineering and Technology Department of Computer Science and Business Systems Karnataka Davanagere577004 India Bapuji Institute of Engineering and Technology Department of Information Science and Engineering Karnataka Davanagere577004 India Karnataka Davanagere577004 India

ISBN: (数字)9798350376517

ISBN: (纸本)9798350376517

This paper presents a novel approach for accurate web traffic prediction on the websites using a Wavelet-Based Hybrid Ensemble Forecasting method. The proposed method decomposes the web traffic time series into time-shifted discrete wavelets, enabling individual forecasting on each decomposed series. Four models - SARIMA, ARIMA, LSTM, and KNN - were evaluated, and their forecasts were combined in a hybrid ensemble model. Evaluation metrics such as accuracy percentage, MAE, RMSE, and MAPE were employed. The hybrid model exhibited superior performance, achieving an accuracy of 99.39%, along with the lowest MAE and RMSE values. Combining forecasts from multiple models significantly improved accuracy and reduced error rates in web traffic prediction. © 2024 IEEE.

关键词： Prediction models

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Dynamic motion of quadrupedal robots on challenging terrain:a kinodynamic optimization approach

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Frontiers of Mechanical engineering 2024年第3期19卷 23-40页

作者： Qi LI Lei DING Xin LUO Engineering Research Center of Hubei Province for Clothing Information Wuhan 430200China School of Computer Science and Artificial Intelligence Wuhan Textile UniversityWuhan 430200China State Key Laboratory of Digital Manufacturing Equipment and Technology Huazhong University of Science and TechnologyWuhan 430074China

The dynamic motion of quadrupedal robots on challenging terrain generally requires elaborate spatial–temporal kinodynamic motion planning and accurate control at higher refresh rate in comparison with regular ***,conventional quadrupedal robots usually generate relatively coarse planning and employ motion replanning or reactive strategies to handle terrain *** resultant complex and computation-intensive controller may lead to nonoptimal motions or the breaking of locomotion *** this paper,a kinodynamic optimization approach is *** generate long-horizon optimal predictions of the kinematic and dynamic behavior of the quadruped robot on challenging terrain,we formulate motion planning as an optimization problem;jointly treat the foot’s locations,contact forces,and torso motions as decision variables;combine smooth motion and minimal energy consumption as the objective function;and explicitly represent feasible foothold region and friction constraints based on terrain *** track the generated motions accurately and stably,we employ a whole-body controller to compute reference position and velocity commands,which are fed forward to joint controllers of the robot’s *** verify the effectiveness of the developed approach through simulation and on a physical quadruped robot *** show that the quadruped robot can successfully traverse a 30°slope and 43% of nominal leg length high step while maintaining the rhythm of dynamic trot gait.

关键词： quadrupedal robot kinodynamic planning nonlinear optimization challenging terrain whole-body control

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Enhancing undulation of soft robots in granular media:A numerical and experimental study on the effect of anisotropic scales

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Biomimetic Intelligence & Robotics 2024年第2期4卷 63-70页

作者： Longchuan Li Chaoyue Zhao Shuqian He Qiukai Qi Shuai Kang Shugen Ma College of Information Science and Technology Bejing University of Chemical TechnologyBejing 100029China School of Engineering Mathematics and Technology University of BristolBristol BS81THUK College of Mechanical and Electrical Engineering Beijing University of Chemical TechnologyBeijing 100029China Thrust of Robotics and Autonomous Systems The Hong Kong University of Science and Technology(Guangzhou)Guangzhou 511453China

Generating efficient locomotion in granular media is important,although it is difficult for *** by the fact that sand vipers usually have saw-like scales,in this study,we design a soft undulation robot with tangential anisotropic friction to enhance the undulation performance of soft robots in granular media.A mathematical model was derived and numerical simulations were conducted accordingly to investigate the effectiveness of tangential friction anisotropy for undulation gait generation in granular *** particular,we introduce a pseudo-rigid-body dynamics model consisting of links and joints while simulating the pneumatic actuation method to more closely approximate the response of soft ***,a soft snake-like robot was fabricated,and its forward and reverse undulations were compared in two sets of controlled *** consistency between the experimental results and the numerical simulations confirms that tangential anisotropic friction induces a propulsive effect in undulation,thereby increasing the robot's locomotion *** discovery provides new insights into the design of undulation robots in granular environments.2024 The Author(s).Published by Elsevier *** behalf of Shandong *** is an open access articleunder the CCBY license(http://***/licenses/by/4.0/).

关键词： Granular media Anisotropicity Pseudo-rigid-body model Soft robot Undulation

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On Cylinder- vs. Sphere-Based Stochastic Modeling of Space-Time Correlated UAV-to-UAV Channels 24

On Cylinder- vs. Sphere-Based Stochastic Modeling of Space-T...

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24th IEEE International Conference on Communication technology, ICCT 2024

作者： Zeng, Linzhou Liao, Xuewen Zhu, Yunzhe Ma, Zhangfeng Jiang, Hao Xi'an Jiaotong University Shaanxi Key Laboratory of Deep Space Exploration Intelligent Information Technology School of Information and Communications Engineering Xi'an710049 China Hunan Institute of Science and Technology School of Information Science and Engineering Yueyang414006 China Shaoyang University School of Information Science and Engineering Shaoyang422000 China Nanjing University of Information Science and Technology School of Artificial Intelligence Nanjing210044 China

ISBN: (纸本)9798350363760

The two-cylinder model and the two-sphere model are two widely-used geometrical channel models that are both the generalizations of the two-ring model;however, a comparative study between them seems to be missing in literature. In this paper, under the background of unmanned aerial vehicle (UAV) air-to-air propagation modeling, similarities and differences between the two geometry-based stochastic models (GBSMs) are analyzed by reviewing their respective closed-form space-time correlation functions (ST-CFs). Notably, some interesting properties of the ST-CFs are analytically obtained, which reveals the behaviors of the ST-CF with respect to several UAV-related parameters, including the moving directions and the antenna orientations. © 2024 IEEE.

关键词： Stochastic models

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Unformer: A Transformer-Based Approach for Adaptive Multiscale Feature Aggregation in Underwater Image Enhancement

IEEE Transactions on Artificial Intelligence

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IEEE Transactions on Artificial Intelligence 2025年第4期6卷 1024-1037页

作者： Qing, Yuhao Wang, Yueying Yan, Huaicheng Xie, Xiangpeng Wu, Zhengguang Shanghai University School of Mechatronic Engineering and Automation Shanghai200444 China East China University of Science and Technology School of Information Science and Engineering Shanghai200237 China Nanjing University of Posts and Telecommunications Institute of Advanced Technology Nanjing210023 China Zhejiang University Institute of Cyber-Systems and Control Hangzhou310027 China

Underwater imaging is often compromised by light scattering and absorption, resulting in image degradation and distortion. This manifests as blurred details, color shifts, and diminished illumination and contrast, thereby hindering advancements in underwater research. To mitigate these issues, we propose Unformer, an innovative underwater image enhancement (UIE) technique that leverages a transformer-based architecture for multiscale adaptive feature aggregation. Our approach employs a multiscale feature fusion strategy that adaptively restores illumination and detail features. We reevaluate the relationship between convolution and transformer to develop a novel encoder structure. This structure effectively integrates both long-range and short-range dependencies, dynamically combines local and global features, and constructs a comprehensive global context. Furthermore, we propose a unique multibranch decoder architecture that enhances and efficiently extracts spatial context information through the transformer module. Extensive experiments on three datasets demonstrate that our proposed method outperforms other techniques in both subjective and objective evaluations. Compared with the latest methods, Unformer has improved the peak signal-to-noise ratio (PSNR) by 19.5% and 14.8% respectively on the LSUI and EUVP datasets. The code is available at: https://***/yhflq/Unformer. © 2024 IEEE.

关键词： Light scattering

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The Seamless Connection Between Underwater and Terrestrial Communication for 6G 26

The Seamless Connection Between Underwater and Terrestrial C...

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26th International Conference on Advanced Communications technology, ICACT 2024

作者： Wu, Tin-Yu Chen, Yi-Kai Tey, Fu-Jie National Pingtung University of Science and Technology Department of Management Information Systems Pingtung Taiwan National Taiwan University of Science and Technology Department of Electrical Engineering Taipei Taiwan

ISBN: (纸本)9791188428120

Underwater communication was chiefly employed in military affairs and underwater exploration in the early days. In recent years, thanks to the progressive advancement of communication networks, many protocols have already been developed for underwater communication. However, due to technological factors, underwater communication is still looking for a seamless link to terrestrial communication. This paper proposes a novel frame format to improve the frame head of underwater communication, and presents a corresponding operation process of underwater nodes with the hope that the data link layer of the OSI 7-layer model provides the Media Access Control (MAC) protocol to the corresponding underwater network. This proposed method can be provided as a standard solution to create a seamless connection between underwater and terrestrial communication. © 2024 Global IT Research Institute - GIRI.

关键词： Head frames

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LSTM-based Forecasting using Policy Stringency and Time-varying Parameters of the SIR Model for COVID-19 19

LSTM-based Forecasting using Policy Stringency and Time-vary...

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19th IEEE International Colloquium on Signal Processing and Its Applications, CSPA 2023

作者： Maniamfu, Pavodi Kameyama, Keisuke University of Tsukuba Degree Programs in Systems and Information Engineering Graduate School of Science and Technology Tsukuba Japan University of Tsukuba Faculty of Engineering Information and Systems Tsukuba Japan

ISBN: (纸本)9781665476928

Accurate forecasting of the number of infections is an important task that can allow health care decision makers to allocate medical resources efficiently during a pandemic. Two approaches have been combined, a stochastic model by Vega et al. for modelling infectious disease and Long Short-Term Memory using COVID-19 data and government's policies. In the proposed model, LSTM functions as a nonlinear adaptive filter to modify the outputs of the SIR model for more accurate forecasts one to four weeks in the future. Our model outperforms most models among the CDC models using the United States data. We also applied the model on the Canadian data from two provinces, Saskatchewan and Ontario where it performs with a low mean absolute percentage error. © 2023 IEEE.

关键词： COVID-19

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Learning-based tracking control of AUV:Mixed policy improvement and game-based disturbance rejection

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CAAI Transactions on Intelligence technology 2025年第2期10卷 510-528页

作者： Jun Ye Hongbo Gao Manjiang Hu Yougang Bian Qingjia Cui Xiaohui Qin Rongjun Ding State Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle College of Mechanical and Vehicle EngineeringHunan UniversityChangshaChina School of Information Science and Technology and Institute of Advanced TechnologyUniversity of Science and Technology of ChinaHefeiChina Nanyang Technological University SingaporeSingapore Wuxi Intelligent Control Research Institute of Hunan University Hunan UniversityWuxiChina

A mixed adaptive dynamic programming(ADP)scheme based on zero-sum game theory is developed to address optimal control problems of autonomous underwater vehicle(AUV)systems subject to disturbances and safe *** combining prior dynamic knowledge and actual sampled data,the proposed approach effectively mitigates the defect caused by the inaccurate dynamic model and significantly improves the training speed of the ADP ***,the dataset is enriched with sufficient reference data collected based on a nominal model without considering modelling ***,the control object interacts with the real environment and continuously gathers adequate sampled data in the *** comprehensively leverage the advantages of model-based and model-free methods during training,an adaptive tuning factor is introduced based on the dataset that possesses model-referenced information and conforms to the distribution of the real-world environment,which balances the influence of model-based control law and data-driven policy gradient on the direction of policy *** a result,the proposed approach accelerates the learning speed compared to data-driven methods,concurrently also enhancing the tracking performance in comparison to model-based control ***,the optimal control problem under disturbances is formulated as a zero-sum game,and the actor-critic-disturbance framework is introduced to approximate the optimal control input,cost function,and disturbance policy,***,the convergence property of the proposed algorithm based on the value iteration method is ***,an example of AUV path following based on the improved line-of-sight guidance is presented to demonstrate the effectiveness of the proposed method.

关键词： adaptive dynamic programming autonomous underwater vehicle game theory optimal control reinforcement learning

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Effect of contact materials on the transient characteristics of vacuum arc plasma and anode erosion

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Plasma science and technology 2024年第11期26卷 170-180页

作者： Ze YANG Dongsheng CAI Qi HUANG Lijun WANG College of Nuclear Technology and Automation Engineering Chengdu University of TechnologyChengdu 610059People’s Republic of China Postdoctoral Mobile Station in Nuclear Science and Technology Chengdu University of TechnologyChengdu 610059People’s Republic of China School of Information Engineering Southwest University of Science and TechnologyMianyang 621010People’s Republic of China State Key Laboratory of Electrical Insulation and Power Equipment Xi’an Jiaotong UniversityXi’an 710049People’s Republic of China

In this study, the mechanisms of the anode phenomena and anode erosion with various contact materials were investigated. Arc parameters were calculated, and the anode temperature was predicted with a transient self-consistent model. The simulation results predicted a constricted arc column and obvious anode phenomena in Cu–Cr alloy contacts than in W–Cu alloy *** observation could be the reason for the concentrated anode erosion in Cu–Cr alloys. For the contacts made by pure tungsten(W) and W–Cu alloy, the anode temperature increased rapidly because of the low specific heat of W. However, the maximum energy flux from the arc column to the anode surface was lower than in other cases. The simulation results were compared with experimental results.

关键词： vacuum arc MHD model anode erosion contact materials

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