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SSRN 2025年

作者： Gu, Xiongwei Xu, Liwei Huang, Xin Chen, Yingjie Shan, Yuanyu Yan, Xiaoyu Liu, Zhaojue Zeng, Hong-Hu Chen, Wenwen Huang, Huanfang Guangxi Key Laboratory of Environmental Pollution Control Theory and Technology Guilin University of Technology Guilin541006 China Engineering Research Center of Watershed Protection and Green Development University of Guangxi Guilin University of Technology Guilin541006 China State Environmental Protection Key Laboratory of Water Environmental Simulation and Pollution Control South China Institute of Environmental Sciences MEE Guangzhou510535 China SCNU Environmental Research Institute Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety & MOE Key Laboratory of Theoretical Chemistry of Environment South China Normal University Guangzhou510006 China

Groundwater is a vital drinking water source for populations in remote karst regions. However, the highly developed karst tube systems facilitate the infiltration of surface wastewater containing N-nitrosamines, raising concerns about groundwater safety. To assess the safety of groundwater and identify which types are safer for consumption, this study investigated N-nitrosamines in various groundwater types, including ground river, karst cavern, well, and mountain spring waters, in Guangxi, a typical karst region in southwestern China. The total concentrations of eight N-nitrosamines in groundwater ranged from 5.1 to 70.3 ng/L, with N-nitrosodiethylamine (NDEA), N-nitrosodimethylamine (NDMA), and N-nitrosopyrrolidine (NPYR) being the dominant species. Ground river water exhibited significantly higher N-nitrosamine concentrations than karst cavern, well, and mountain spring waters. Significant correlations between N-nitrosamines and dissolved inorganic nitrogen suggested their co-emissions from domestic wastewater and the secondary formation potential of N-nitrosamines in groundwater. Redundancy analysis further identified domestic and swine wastewater as the primary sources. Ground river and mountain spring waters posed the highest risks among the four groundwater types, with 30% and 20% of sites, respectively, exceeding acceptable cancer risk thresholds. These findings underscore the importance of thorough water treatment before groundwater is used for drinking. Strict livestock farming and domestic wastewater discharge regulations are essential to mitigate contamination risks, particularly in karst areas. © 2025, The Authors. All rights reserved.

关键词： Nitrosamines

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A control framework for autonomous e-scooters

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IFAC-PapersOnLine 2021年第2期54卷 252-258页

作者： Raffaele Soloperto Philipp Wenzelburger David Meister Dominik Scheuble Veronika S.M. Breidohr Frank Allgöwer University of Stuttgart Institute for Systems Theory and Automatic Control Pfaffenwaldring 9 70569 Stuttgart Germany University of Stuttgart Faculty 7: Engineering Design Production Engineering and Automotive Engineering Pfaffenwaldring 9 70569 Stuttgart Germany

In this paper, we address the core challenges of self-stabilization, obstacle detection, and collision avoidance arising when developing autonomous electric scooters for sharing systems. In particular, we firstly demonstrate how an e-scooter can balance itself by the usage of a reaction wheel combined with a braking mechanism. Secondly, we show how a depth-camera can be utilized to generate a grid map representation of the environment surrounding the e-scooter and how this can be used to design a computationally tractable algorithm which ensures obstacle avoidance as well as path following. Finally, the goal of this paper is to provide a starting point for the development of autonomous e-scooters for sharing systems by combining approaches from various research communities in a common application framework.

关键词： E-scooters Self-stabilization Collision avoidance Obstacle detection Smart-mobility

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Spectral asymmetry effect in terahertz generation by two-color ionizing femtosecond pulses

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Physical Review A 2025年第2期111卷 023508-023508页

作者： Zhiwen Zhang Vasily A. Kostin Alexander A. Silaev Zefu Liu Shixiang Wang Chenhui Lu Zhengquan Fan Yi Liu Shanghai Key Lab of Modern Optical System University of Shanghai for Science and Technology Shanghai 200093 China Gaponov-Grekhov Institute of Applied Physics of the Russian Academy of Sciences Nizhny Novgorod 603950 Russia Department of Control Theory Lobachevsky State University of Nizhny Novgorod Nizhny Novgorod 603022 Russia Department of Electrodynamics Lobachevsky State University of Nizhny Novgorod Nizhny Novgorod 603022 Russia School of Mechanical and Automotive Engineering Shanghai University of Engineering Science Shanghai 201620 China CAS Center for Excellence in Ultra-Intense Laser Science Shanghai 201800 China

Ultrabroadband intense terahertz (THz) radiation generated by two-color femtosecond pulses is a promising tool for applications in many areas involving linear and nonlinear terahertz spectroscopy and light-matter interactions. The essential challenge is to understand and control the THz spectrum in order to optimize it for specific applications. Here we study the frequency-dependent modulation of the THz spectrum with the relative phase between the second-harmonic and fundamental-field components of the linearly polarized femtosecond pulse. Analytical consideration reveals the physical reason for the suppression of the spectral modulation, which is local (induced by the local ionization dynamics and electron motion and not related to propagation effects such as phase slippage) and coherent (associated only with the phase-dependent coherent THz waveforms). The spectral modulation is sensitive to the frequency detuning, both its absolute value and the sign. Having this asymmetric dependence on the detuning, the suppressed modulation can be observed even in commensurate two-color pulses with the effect enhanced additionally by the ionization blueshift. The theoretical findings are confirmed by the experiment, where we employed chirped two-color pulses with a variable time delay between their components, effectively enabling a scan over the detuning. The obtained results show that not only the THz yield but also the spectral shape can be effectively controlled by the relative phase and may be very sensitive to a small frequency detuning arising naturally during two-color pulse propagation.

关键词： Terahertz spectroscopy

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Reinforcement Learning and Trajectory Planning based on Model Approximation with Neural Networks applied to Transition Problems

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IFAC-PapersOnLine 2020年第2期53卷 1581-1587页

作者： Max Pritzkoleit Carsten Knoll Klaus Röbenack TU Dresden Faculty of Electrical and Computer Engineering Institute of Control Theory Dresden Germany

In this paper we use a multilayer neural network to approximate the dynamics of nonlinear (mechanical) control systems. Furthermore, these neural network models are combined with offline trajectory planning, to form a model-based reinforcement learning (RL) algorithm, suitable for transition problems of nonlinear dynamical systems. We evaluate the algorithm on the swing-up of the cart-pole benchmark system and observe a significant performance gain in terms of data efficiency compared to a state-of-the-art model-free RL method (Deep Deterministic Policy Gradient (DDPG)). Additionally, we present first experimental results on a cart-triple-pole system test bench. For a simple transition problem, the proposed algorithm shows a good controller performance.

关键词： Trajectory planning Reinforcement learning Learning control Neural-network models Model approximation Tracking control

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Self-triggered MPC robust to bounded packet loss via a min-max approach: extended version

arXiv

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arXiv 2022年

作者： Wildhagen, Stefan Pezzutto, Matthias Schenato, Luca Allgöwer, Frank University of Stuttgart Institute for Systems Theory and Automatic Control Germany Université Libre de Bruxelles Service d’Automatique et d’Analyse des Systèmes Belgium University of Padova Department of Information Engineering Italy

Networked control Systems typically come with a limited communication bandwidth and thus require special care when designing the underlying control and triggering law. A method that allows to consider hard constraints on the communication traffic as well as on states and inputs is self-triggered model predictive control (MPC). In this scheme, the optimal length of the sampling interval is determined proactively using predictions of the system behavior. However, previous formulations of self-triggered MPC have neglected the widespread phenomenon of packet loss, such that these approaches might fail in practice. In this paper, we present a novel self-triggered MPC scheme which is robust to bounded packet loss by virtue of a min-max optimization problem. We prove recursive feasibility, constraint satisfaction and convergence to the origin for any possible packet loss realization consistent with the boundedness constraint, and demonstrate the advantages of the proposed scheme in a numerical example. Copyright © 2022, The Authors. All rights reserved.

关键词： Model predictive control

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Do We Run Large-scale Multi-Robot Systems on the Edge? More Evidence for Two-Phase Performance in System Size Scaling

Do We Run Large-scale Multi-Robot Systems on the Edge? More ...

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IEEE International Conference on Robotics and Automation (ICRA)

作者： Jonas Kuckling Robin Luckey Viktor Avrutin Andrew Vardy Andreagiovanni Reina Heiko Hamann Department of Computer and Information Science University of Konstanz Konstanz Germany Centre for the Advanced Study of Collective Behaviour University of Konstanz Germany Institute of Computer Engineering University of Lübeck Lübeck Germany Institute for Systems Theory and Automatic Control University of Stuttgart Stuttgart Germany Department of Computer Science and the Department of Electrical and Computer Engineering Memorial University of Newfoundland St. John’s Canada IRIDIA Université Libre de Bruxelles Brussels Belgium

ISBN: (数字)9798350384574

ISBN: (纸本)9798350384581

With increasing numbers of mobile robots arriving in real-world applications, more robots coexist in the same space, interact, and possibly collaborate. Methods to provide such systems with system size scalability are known, for example, from swarm robotics. Example strategies are self-organizing behavior, a strict decentralized approach, and limiting the robot-robot communication. Despite applying such strategies, any multi-robot system breaks above a certain critical system size (i.e., number of robots) as too many robots share a resource (e.g., space, communication channel). We provide additional evidence based on simulations, that at these critical system sizes, the system performance separates into two phases: nearly optimal and minimal performance. We speculate that in real-world applications that are configured for optimal system size, the supposedly high-performing system may actually live on borrowed time as it is on a transient to breakdown. We provide two modeling options (based on queueing theory and a population model) that may help to support this reasoning.

关键词： Limiting System performance Space communications Scalability Sociology Swarm robotics Mobile robots

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Data-driven control of dynamic event-triggered systems with delays

arXiv

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arXiv 2021年

作者： Wang, Xin Sun, Jian Berberich, Julian Wang, Gang Allgöwer, Frank Chen, Jie State Key Lab of Intelligent Control and Decision of Complex Systems School of Automation Beijing Institute of Technology Beijing100081 China Institute for Systems Theory and Automatic Control University of Stuttgart Stuttgart70550 Germany Department of Control Science and Engineering Tongji University Shanghai201804 China

This paper studies data-driven control of unknown sampled-data systems with communication delays under an event-triggering transmission mechanism. Data-based representations for stochastic linear systems with a known or an unknown system input matrix are first developed, along with a novel class of dynamic triggering schemes for sampled-data systems with time delays. A model-based stability condition for the resulting event-triggered time-delay system is established using a looped-functional approach. Combining this model-based condition with the data-driven representations, data-based stability conditions are derived. Building on the data-based conditions, methods for co-designing the controller gain and the event-triggering matrix are subsequently provided for both cases with or without using the input matrix. Finally, a numerical example is presented to corroborate the role of additional prior knowledge of the input matrix in reducing the conservatism of stability conditions, as well as the merits of our approaches relative to existing results. © 2021, CC BY.

关键词： Sampled data control systems

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On functional observers for polynomial systems with nonlinear oscillations

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PAMM 2023年第2期23卷

作者： Klaus Röbenack Daniel Gerbet Institute of Control Theory Faculty of Electrical and Computer Engineering TUD Dresden University of Technology Dresden Germany

In this contribution we discuss the design of functional observers for polynomial systems. Our approach is based on a high gain design employing an embedded observer. The functional to be estimated is generated from the high gain observer's state. The restriction to polynomial systems allows the representation of the system's and the observer's dynamics as polynomial ideals. For the calculations we utilize methods from algebraic geometry. Our approach is illustrated on a chaotic system.

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An embedding observer for nonlinear dynamical systems with global convergence

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PAMM 2023年第4期23卷

作者： Daniel Gerbet Klaus Röbenack Institute of Control Theory Faculty of Electrical and Computer Engineering TUD Dresden University of Technology Dresden Germany

State observers for nonlinear systems are often designed for a canonical form of this system. However, this form may possess singular points, where the vector field is not defined or a Lipschitz condition is not fulfilled. This unpleasant behavior can possibly be avoided using an embedding into a higher dimensional space. A construction of such an embedding and the corresponding inverse map is discussed for polynomial systems using methods from algebraic geometry.

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Occurrence, Distribution, and Ecological Risk Assessment of Pharmaceuticals and Personal Care Products in the Surface Water: A Case Study of Lipu River, Guilin, China

SSRN

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SSRN 2023年

作者： Zhang, Ya-Nan Huang, Gui-Bin Zhang, Qin Bi, Xiao-Qian Chu, Hang Liu, Zi-Xuan Luo, Jun Bai, Shao-Yuan Mo, Sheng-Peng Jiang, Xin Wang, Hui Fu, Ming-Ming College of Environmental Science and Engineering Guilin University of Technology Guilin541004 China The Guangxi Key Laboratory of Theory and Technology for Environmental Pollution Control Guilin University of Technology Guilin541004 China Collaborative Innovation Center for Water Pollution Control and Water Safety in Karst Area Guilin University of Technology Guilin541004 China State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil Science Chinese Academy of Sciences Nanjing210008 China Guilin University of Technology China

Pharmaceuticals and personal care products (PPCPs) are emerging organic pollutants in environmental matrices. In this study, the surface waters of the Lipu River and its major tributaries were sampled and investigated in Lipu, Guilin, China. The occurrence, concentration distribution, spatial distribution, and ecological risk assessment of 30 target PPCPs in the Lipu River were analyzed. Among the antibiotics, the main pollutants in the Lipu River were flumequine and lomefloxacin;while among the non-antibiotics, caffeine was the main pollutant. The total concentration of PPCPs in all samples ranged from 33.3 to 165.6 ng/L. The maximum concentration of caffeine was 53.6 ng/L, with a mean concentration of 12.59 ng/L and a median concentration of 8.5 ng/L. Through spatial distribution analysis, the pollution in the main tributaries of Lipu River is more serious than the main stream, and the overall concentration distribution in the midstream is significantly higher than the upstream and downstream, with midstream > downstream > upstream. The ecological risk evaluation showed that sarafloxacin, ciprofloxacin, norfloxacin, and caffeine have high ecological risk (RQ > 1) and lomefloxacin, enrofloxacin, oxolinic acid, flumequine, sulfadiazine, sulfamethazine, tetracycline, oxytetracycline, and chlortetracycline had a medium risk to aquatic organisms (0.1 ≤ RQ © 2023, The Authors. All rights reserved.

关键词： Antibiotics

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