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arXiv 2022年

作者： Nita, Lucian Vila, Eduardo M.G. Zagorowska, Marta A. Kerrigan, Eric C. Nie, Yuanbo McInerney, Ian Falugi, Paola Department of Electrical & Electronic Engineering Imperial College London LondonSW7 2AZ United Kingdom Department of Automatic Control and Systems Engineering University of Sheffield SheffieldS1 3JD United Kingdom

Introducing flexibility in the time-discretisation mesh can improve convergence and computational time when solving differential equations numerically, particularly when the solutions are discontinuous, as commonly found in control problems with constraints. State-of-the-art methods use fixed mesh schemes, which cannot achieve superlinear convergence in the presence of non-smooth solutions. In this paper, we propose using a flexible mesh in an integrated residual method. The locations of the mesh nodes are introduced as decision variables, and constraints are added to set upper and lower bounds on the size of the mesh intervals. We compare our approach to a uniform fixed mesh on a real-world satellite reorientation example. This example demonstrates that the flexible mesh enables the solver to automatically locate the discontinuities in the solution, has superlinear convergence and faster solve times, while achieving the same accuracy as a fixed mesh. © 2022, CC BY.

关键词： Mesh generation

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Solving optimal control problems with non-smooth solutions using an integrated residual method and flexible mesh

arXiv

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arXiv 2022年

作者： Nita, Lucian Kerrigan, Eric C. Vila, Eduardo M.G. Nie, Yuanbo Department of Electrical & Electronic Engineering Imperial College London LondonSW7 2AZ United Kingdom Department of Automatic Control and Systems Engineering University of Sheffield SheffieldS1 3JD United Kingdom

Solutions to optimal control problems can be discontinuous, even if all the functionals defining the problem are smooth. This can cause difficulties when numerically computing solutions to these problems. While conventional numerical methods assume state and input trajectories are continuous and differentiable or smooth, our method is able to capture discontinuities in the solution by introducing time-mesh nodes as decision variables. This allows one to obtain a higher accuracy solution for the same number of mesh nodes compared to a fixed time-mesh approach. Furthermore, we propose to first solve a sequence of suitably-defined least-squares problems to ensure that the error in the dynamic equation is below a given tolerance. The cost functional is then minimized subject to an inequality constraint on the dynamic equation residual. We demonstrate our implementation on an optimal control problem that has a chattering solution. Solving such a problem is difficult, since the solution involves infinitely many switches of decreasing duration. This simulation shows how the flexible mesh is able to capture discontinuities present in the solution and achieve superlinear convergence as the number of mesh intervals is increased. © 2022, CC BY.

关键词： Numerical methods

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Finite Neural Networks as Mixtures of Gaussian Processes: From Provable Error Bounds to Prior Selection

arXiv

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arXiv 2024年

作者： Adams, Steven Patanè, Andrea Lahijanian, Morteza Laurenti, Luca Delft Center for Systems and Control Technical Universiy of Delft Delft2628 CD Netherlands School of Computer Science and Statistics Trinity College Dublin Dublin 2 Ireland Department of Aerospace Engineering Sciences and Computer Science University of Colorado Boulder BoulderCO80303 United States

Infinitely wide or deep neural networks (NNs) with independent and identically distributed (i.i.d.) parameters have been shown to be equivalent to Gaussian processes. Because of the favorable properties of Gaussian processes, this equivalence is commonly employed to analyze neural networks and has led to various breakthroughs over the years. However, neural networks and Gaussian processes are equivalent only in the limit;in the finite case there are currently no methods available to approximate a trained neural network with a Gaussian model with bounds on the approximation error. In this work, we present an algorithmic framework to approximate a neural network of finite width and depth, and with not necessarily i.i.d. parameters, with a mixture of Gaussian processes with error bounds on the approximation error. In particular, we consider the Wasserstein distance to quantify the closeness between probabilistic models and, by relying on tools from optimal transport and Gaussian processes, we iteratively approximate the output distribution of each layer of the neural network as a mixture of Gaussian processes. Crucially, for any NN and ǫ > 0 our approach is able to return a mixture of Gaussian processes that is ǫ-close to the NN at a finite set of input points. Furthermore, we rely on the differentiability of the resulting error bound to show how our approach can be employed to tune the parameters of a NN to mimic the functional behavior of a given Gaussian process, e.g., for prior selection in the context of Bayesian inference. We empirically investigate the effectiveness of our results on both regression and classification problems with various neural network architectures. Our experiments highlight how our results can represent an important step towards understanding neural network predictions and formally quantifying their uncertainty. © 2024, CC BY.

关键词： Deep neural networks

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Sliding-Mode control of Phase Shift for Two-Rotor Vibration Setup 8th

Sliding-Mode Control of Phase Shift for Two-Rotor Vibration ...

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Proceedings of the 8th International Conference on Interactive Collaborative Robotics, ICR 2023

作者： Kuznetsov, Nikolay Andrievsky, Boris Zaitceva, Iuliia Akimova, Elizaveta Department of Applied Cybernetics Faculty of Mathematics and Mechanics St. Petersburg State University 28 Universitetsky Pr. Stary Peterhof St. Petersburg198504 Russia Institute for Problems in Mechanical Engineering of Russian Academy of Sciences 61 Bol‘Shoy Prospect V.O. St. Petersburg199178 Russia Department of Automatic Control Systems St. Petersburg Electrotechnical University "LETI" 5 Professora Popova St. St. Petersburg197376 Russia

ISBN: (纸本)9783031431104

This paper successfully developed and studied a phase shift control system for a two-rotor vibration mechatronic setup, aiming to maintain the desired revolving speed of the rotors. The sliding mode motion was achieved by utilizing a relay controller in the phase loop, while PI controllers were employed in the velocity control loops. Through numerical study and simulations using the parameters of the Mechatronic Vibration Setup SV-2M, the effectiveness of the proposed velocity and phase shift control laws was demonstrated. The possibility of sliding mode occurrence in the phase shift loop was examined through analytical and numerical analysis, confirming its presence. The relationship between the relative degree of the transfer function of the plant and the possibility of the occurrence of a sliding mode is analyzed based on the locus of a perturbed relay system approach. Simulation results indicated that sliding mode motion appeared after a finite transient time and showcased the dynamical properties of the closed-loop system. In conclusion, the findings of this study validate the efficacy of the phase shift control system in achieving the desired rotor speed and demonstrate the feasibility of implementing sliding mode motion in the mechatronic setup. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.

关键词： Induction motors

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Redox deracemization of α-substituted 1,3-dihydroisobenzofurans

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Chinese chemical Letters 2021年第7期32卷 2305-2308页

作者： Xiaohan Chen Ran Zhao Ziqiang Liu Shutao Sun Yingang Ma Qingyun Liu Xia Sun Lei Liu School of Pharmaceutical Sciences Cheeloo College of MedicineShandong UniversityJi'nan 250012China College of Chemical and Biological Engineering State Key Laboratory of Mining Disaster Prevention and Control Co-founded by Shandong Province and the Ministry of Science and TechnologyShandong University of Science and TechnologyQingdao 266590China School of Chemistry and Chemical Engineering Shandong UniversityJi'nan 250100China Shenzhen Research Institute of Shandong University Shenzhen 518057China Department of Pharmacology School of Basic Medical SciencesCheeloo College of MedicineShandong UniversityJi'nan 250012China

Chiralα-substituted 1,3-dihydroisobenzofurans are key scaffolds in a number of bioactive natural products and synthetic ***,catalytic asymmetric approaches have been rarely ***,a redox deracemization technology is adopted to address the catalytic asymmetric synthesis.A broad range ofα-aryl substituted 1,3-dihydroisobenzofurans are effectively deracemized in high efficiency with excellent ee.α-Alkynyl substituted ethers were also compatible with the deracemization technology.

关键词： 1,3-Dihydroisobenzofuran Asymmetric catalysis Redox deracemization Oxocarbenium ion Synthetic method

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Selective Capture of Palladium by Protonation-Armed Pyridine Nitrogen in Extreme Water Environments

SSRN

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SSRN 2023年

作者： Li, Dewei Shao, Penghui Li, Min Liu, Wenjin Yao, Ziwei Zhang, Li Meng, Zhu Yang, Liming Shi, Hui Tang, Huan Luo, Xubiao Luo, Shenglian National-Local Joint Engineering Research Center of Heavy Metals Pollutants Control and Resource Utilization Nanchang Hangkong University Nanchang330063 China Key Laboratory of Northwest Water Resource Environment and Ecology MOE and Shaanxi Key Laboratory of Environmental Engineering Xi’an University of Architecture and Technology Xi’an710055 China Department of Chemical Engineering Chongqing University of Science and Technology Chongqing401331 China

Due to the hostile environment in which it is recovered, selective separation of palladium from the leachate of spent catalysts containing palladium is of considerable utility but faces substantial obstacles. This work designed and synthesized a bipyridine-based porous organic polymer (POP-BPy). Meanwhile, its adsorption characteristics and the mechanism of adsorption were examined. In hostile conditions, the resultant POP-BPy display exceptional mechanical stability and environmental resistance. Impressively, POP-BPy has an excellent adsorption capacity of Pd(II) (248 mg/g) in harsh environments (AR"1+1"), and had superior selectivity and rapid kinetics. The selectivity of POP-BPy for Pd(II) was verified in combination with relevant experiments (βPd(II)/Pt(II)=36.19, βPd(II)/Pt(II)=23.90). Furthermore, combining density functional theory and molecular dynamics simulations, the mechanism of selectivity of POP-BPy for Pd(II) was revealed from static adsorption sites to dynamic adsorption processes, which attributed to the strong attraction of protonated pyridine nitrogen to PdCl42- and site suitability. Furthermore, the application of POP-BPy to spent catalyst recovery resulted in up to 100% removal of Pd(II) from the actual leaching solution, and fixed bed column experiments can effectively treat 2688 bed volumes of feed streams. Overall, this work has opened up new avenues for the selective recycling of valuable metals in harsh environments. © 2023, The Authors. All rights reserved.

关键词： Mechanical stability

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Design and Implementation of a Two-Limbed 3T1R Haptic Device

Design and Implementation of a Two-Limbed 3T1R Haptic Device

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IEEE/RSJ International Conference on Intelligent Robots and systems (IROS)

作者： Long Kang Yang Yang Byung-Ju Yi PCA Lab Key Laboratory of Intelligent Perception and Systems for High-Dimensional Information of Ministry of Education School of Computer Science and Engineering Nanjing University of Science and Technology Nanjing China Xi'an Modern Control Technology Research Institute Xi'an China School of Automation Nanjing University of Information Science and Technology Nanjing China Department of the Electronic Systems Engineering Hanyang University Ansan South Korea

This paper presents a haptic device with a simple architecture of only two limbs that can provide translational motion in three degrees of freedom (DOF) and one-DOF rotational motion. Actuation redundancy eliminates all forward-kinematic singularities and improves the motion-force transmission property. Thanks to the special structure of the kinematic chains, all actuators are close to the base and full gravity compensation is achieved passively by using springs. Force producibility analysis shows that this haptic device is able to produce long-term continuous force feedback of 15–30 N in each direction. By developing a prototype of the haptic device and a virtual three-dimensional simulator, a preliminary performance evaluation of the haptic device was conducted. In addition, a torque distribution algorithm considering a relaxed form of actuator-torque saturation was experimentally evaluated, and a comparison with other algorithms reveals that this algorithm offers several advantages.

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Optimizing chemical Phosphorus Removal for Wastewater Treatment: Insights from Binary Machine Learning Modeling with Elasticity and Productivity Evaluation

SSRN

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SSRN 2024年

作者： Huang, Runyao Wang, Hongtao Mąkinia, Jacek Jin, Sitian Zhou, Zhen Zhang, Ming Yu, Chenyang Xie, Li College of Environmental Science and Engineering Key Laboratory of Yangtze River Water Environment Ministry of Education State Key Laboratory of Pollution Control and Resource Reuse Tongji University Shanghai200092 China UNEP-Tongji Institute of Environment for Sustainable Development Tongji University Shanghai200092 China Shanghai Institute of Pollution Control and Ecological Security Tongji University Shanghai200092 China Faculty of Civil and Environmental Engineering Gdańsk University of Technology Narutowicza Street 11/12 Gdańsk80-233 Poland Shanghai Engineering Research Center of Energy – Saving in Heat Exchange Systems College of Environmental and Chemical Engineering Shanghai University of Electric Power Shanghai200090 China Shanghai Chengtou Wastewater Treatment Co. Ltd Shanghai201203 China

Ensuring compliance with legal discharge regulations for total phosphorus (TP) is crucial in wastewater treatment plants (WWTPs), considering the minimization of chemical consumption like poly aluminum chloride (PAC). However, the relationship between actual TP removal and PAC consumption presents numerical complexities, hindering data-driven modeling efforts. This study analyzed daily observations over one-year period in WWTP to assess elasticity and productivity, revealing decoupling and congestion patterns between PAC consumption and TP removal. Binary dependent features were established for modeling. The results highlighted the importance of wastewater inflow and biological treatment features, suggesting PAC reduction to mitigate decoupling and congestion. Thus, insights were obtained for sustainable WWTP operations to sufficiently leverage influent characteristics and utilize biological treatment to minimize chemical dosing. The assessment workflow, incorporating elasticity and productivity considerations, establishes a robust basis for further optimization within a normalized production trajectory in wastewater sector, concurrently lowering resource depletion and enhancing environmental benefits. © 2024, The Authors. All rights reserved.

关键词： Wastewater treatment

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Bio-inspired Multi-agent Model and Optimization Strategy for Collaborative Aerial Transport

Bio-inspired Multi-agent Model and Optimization Strategy for...

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2021中国智能自动化大会(CIAC 2021)

作者： Kangyao Huang Jingyu Chen John Oyekan Xinyu Zhang Tsinghua University School of Vehicle and Mobility Department of Automatic Control and Systems Engineering The University of Sheffield

Collaboration between robots provides solutions for transporting more complex and heavier loads. In this work, inspired by the ant colony foraging and transport, we put forward two collaborative models, Coupled-Carriers and Navigator-Carrier, for aerial cooperative transport. To achieve this, a linear quadratic regulator(LQR) is applied to optimize the performance. The results show the task of dual-drone transport of a bar load is successfully accomplished.

关键词： Cooperative transport Swarm intelligence Swarm robotics Multi-agent system Optimal control

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Lidar-Based Multiple Object Tracking with Occlusion Handling

Lidar-Based Multiple Object Tracking with Occlusion Handling

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IEEE/RSJ International Conference on Intelligent Robots and systems (IROS)

作者： Ruo-Tsz Ho Chieh-Chih Wang Wen-Chieh Lin Institute of Electrical and Control Engineering National Yang Ming Chiao Tung University Hsinchu Taiwan Department of Electronics and Electrical Engineering National Yang Ming Chiao Tung University Mechanical and Mechatronics Systems Research Laboratories Industrial Technology Research Institute Hsinchu Taiwan Department of Computer Science National Yang Ming Chiao Tung University Hsinchu Taiwan

Occlusion remains an issue in multiple object tracking, which could cause ambiguity in object detection, such as incorrect or missing detection. Under occlusion, a track could experience an early termination, resulting in identity switches and/or fragmentation. To recover from different lengths of occlusions, the track should be maintained by considering its occlusion status. To address the issues mentioned above, we propose an indicator that can model the track's occlusion extent via geometric information provided by LiDAR data. Through incorporating the indicator into the track management and data association process, it is feasible to prevent tracks from premature termination. The proposed method is evaluated on the collected dataset which undergoes frequent and severe occlusions. Compared to the state-of-the-art probabilistic tracking approach, our approach achieves improvements of 3.26% in MOTA and 5.36% in IDF1. Additionally, we obtain 9.89% improvements in IDF1 specifically for objects experiencing severe occlusions.

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