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Detecting dynamical causality by intersection cardinal concavity

Fundamental Research 2023年

作者： Tao, Peng Wang, Qifan Shi, Jifan Hao, Xiaohu Liu, Xiaoping Min, Bin Zhang, Yiheng Li, Chenyang Cui, He Chen, Luonan Key Laboratory of Systems Health Science of Zhejiang Province School of Life Science Hangzhou Institute for Advanced Study University of Chinese Academy of Sciences Chinese Academy of Sciences Hangzhou 310024 China Key Laboratory of Systems Biology Shanghai Institute of Biochemistry and Cell Biology Center for Excellence in Molecular Cell Science Chinese Academy of Sciences Shanghai 200031 China Center for Excellence in Brain Science and Intelligent Technology Institute of Neuroscience Chinese Academy of Sciences Shanghai 200031 China Chinese Institute for Brain Research Beijing 102206 China University of Chinese Academy of Sciences Beijing 100049 China Research Institute of Intelligent Complex Systems Fudan University Shanghai 200433 China State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science Institutes of Brain Science Fudan University Shanghai 200032 China School of Life Science and Technology ShanghaiTech University Shanghai 201210 China

Discovering causality from observed time series data is of great importance in various disciplines but also a challenging task. In recent years, cross-mapping methods have been developed to solve the non-separability or false-negative problem that traditional methods, e.g., Granger causality or transfer entropy, cannot handle. However, these cross-mapping methods suffer still from nonlinearity and robustness problems on the noisy data. Here, we propose cross-mapping cardinality (CMC), which detects direct causality in a robust and nonlinear manner by quantifying the intersectional cardinality (IC) from the neighbors of the cause variable to the cross-mapping neighbors of the effect variable in the delay embedding space. We theoretically and computationally show the new causal concept “IC concavity”, i.e. concave IC curve against the neighbor size implies causality in the sense of dynamical causality, in contrast to the non-causality of linear IC curve. Thus, the causal strength is measured reliably by the IC curve, which exploits both IC continuity and information transfer of the cross-mapping function from effect to cause variables. Through verification on various simulated and real-world datasets, the accuracy and robustness of CMC are demonstrated significantly better than existing methods. In particular, we validated CMC with the pulse data from motor cortex neurons by training a rhesus monkey to conduct a flexible manual interception experiment. CMC effectively identified the causal relations between neurons while the traditional methods failed. In summary, our approach with the new concept of IC concavity provides a powerful data-driven tool for detecting dynamical causality in complex systems. © 2023

关键词： Causal inference Cross mapping Dynamical causality False-negative problem Non-separability problem Nonlinear causality

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Nonlocal thermo-elastic constitutive relation of fibre-reinforced composites

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Acta Mechanica Sinica 2020年第1期36卷 176-187页

作者： Linjuan Wang Jifeng Xu Jianxiang Wang Bhushan LKarihaloo State Key Laboratory for Turbulence and Complex Systems Department of Mechanics and Engineering ScienceCollege of EngineeringPeking UniversityBeijing100871China CAPT-HEDPS and IFSA Collaborative Innovation Center of MoECollege of EngineeringPeking UniversityBeijing100871China Beijing Aeronautical Science and Technology Research Institute Beijing100083China School of Engineering Cardiff UniversityCardiffCF243AAUK

The effective properties of composite materials have been predicted by various micromechanical *** composite materials of constituents which are described by the classical governing equations of the local form,the conventional micromechanical schemes usually give effective properties of the local ***,it is recognized that under general loading conditions,spatiotemporal nonlocal constitutive equations may better depict the macroscopic behavior of these *** this paper,we derive the thermo-elastic dynamic effective governing equations of a fibre-reinforced composite in a coupled spatiotemporal integral *** coupled equations reduce to the spatial nonlocal peridynamic formulation when the microstructural inertial effects are *** static deformation and steady-state heat conduction,we show that the integral formulation is superior at capturing the variations of the average displacement and temperature in regions of high gradients than the conventional micromechanical *** approach can be applied to analogous multi-field coupled problems of composites.

关键词： Nonlocal theory Thermoelasticity Composite materials Constitutive equations

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Dispersions and magnetism of strain-induced pseudo Landau levels in Bernal-stacked bilayer graphene

arXiv

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arXiv 2024年

作者： Liu, Tianyu Li, Jun-Hong Zhu, Xingchuan Guo, Huaiming Lu, Hai-Zhou Xie, X.C. International Quantum Academy Shenzhen518048 China Shenzhen Key Laboratory of Quantum Science and Engineering Shenzhen518055 China Max Planck Institute for the Physics of Complex Systems Dresden01187 Germany Shenzhen518055 China Shenzhen518045 China School of Intelligent Manufacturing Nanjing University of Science and Technology Nanjing210094 China School of Physics Beihang University Beijing100191 China Fudan University Shanghai200433 China International Center for Quantum Materials School of Physics Peking University Beijing100871 China Hefei National Laboratory Hefei230088 China

Elastic strain can displace the massless Dirac fermions in monolayer graphene in a space-dependent fashion, similar to the effect of an external magnetic field, thus giving rise to Landau quantization. We here show that the strain-induced Landau quantization can also take place in Bernal-stacked bilayer graphene, where the low-energy excitations are massive rather than Dirac-like. The zigzag ribbon of Bernal-stacked bilayer graphene realizes a two-legged Su-Schrieffer-Heeger model with a domain wall, which coincides with the guiding center of the strain-induced pseudo Landau levels. We reduce the lattice model of the ribbon in the vicinity of the guiding center into an exactly solvable coupled Dirac model and analytically derive the dispersions of the strain-induced pseudo Landau levels. Remarkably, the zeroth and first pseudo Landau levels are dispersionless and sublattice-polarized. We elucidate that the interaction on these two pseudo Landau levels results in a global antiferromagnetic order. Our study extends the strain-induced Landau quantization to the massive excitations and indicates strain as a tuning knob of magnetism. Copyright © 2024, The Authors. All rights reserved.

关键词： Antiferromagnetism

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S4TP: Social-Suitable and Safety-Sensitive Trajectory Planning for Autonomous Vehicles

arXiv

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arXiv 2024年

作者： Wang, Xiao Tang, Ke Dai, Xingyuan Xu, Jintao Du, Quancheng Ai, Rui Wang, Yuxiao Gu, Weihao Engineering Research Center of Autonomous Unmanned System Technology Ministry of Education Anhui University Hefei230031 China Haomo Technology Co. Ltd. Beijing100192 China The State Key Laboratory for Management and Control of Complex Systems Institute of Automation Chinese Academy of Sciences Beijing100190 China Qingdao Academy of Intelligent Industries Qingdao266114 China The School of Computer and Communication Engineering University of Science and Technology Beijing Beijing100083 China The School of Artificial Intelligence University of Chinese Academy of Sciences Beijing100049 China

In public roads, autonomous vehicles (AVs) face the challenge of frequent interactions with human-driven vehicles (HDVs), which render uncertain driving behavior due to varying social characteristics among humans. To effectively assess the risks prevailing in the vicinity of AVs in social interactive traffic scenarios and achieve safe autonomous driving, this article proposes a social-suitable and safety-sensitive trajectory planning (S4TP) framework. Specifically, S4TP integrates the Social-Aware Trajectory Prediction (SATP) and Social-Aware Driving Risk Field (SADRF) modules. SATP utilizes Transformers to effectively encode the driving scene and incorporates an AV’s planned trajectory during the prediction decoding process. SADRF assesses the expected surrounding risk degrees during AVs-HDVs interactions, each with different social characteristics, visualized as two-dimensional heat maps centered on the AV. SADRF models the driving intentions of the surrounding HDVs and predicts trajectories based on the representation of vehicular interactions. S4TP employs an optimization-based approach for motion planning, utilizing the predicted HDVs’ trajectories as input. With the integration of SADRF, S4TP executes real-time online optimization of the planned trajectory of AV within low-risk regions, thus improving the safety and the interpretability of the planned trajectory. We have conducted comprehensive tests of the proposed method using the SMARTS simulator. Experimental results in complex social scenarios, such as unprotected left-turn intersections, merging, cruising, and overtaking, validate the superiority of our proposed S4TP in terms of safety and rationality. S4TP achieves a pass rate of 100% across all scenarios, surpassing the current state-of-the-art methods Fanta of 98.25% and Predictive-Decision of 94.75%. Copyright © 2024, The Authors. All rights reserved.

关键词： Autonomous vehicles

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Synthesis, characterization and dielectric properties of a novel temperature stable（1-x）CoTiNb2O8-xZnNb2O6 ceramic

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Journal of Advanced Ceramics 2019年第2期8卷 228-237页

作者： Mengjuan WU Yingchun ZHANG Maoqiao XIANG School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China

(1-x)CoTiNb2O8-x ZnNb2O6 microwave dielectric ceramics were prepared via the conventional solid-state reaction route with the aim of reducing thetf value and improving the thermal *** phase composition and the microstructure were investigated using X-ray diffraction,Raman spectra,and scanning electron microscopy.A set of phase transitions which were induced by composition had been confirmed via the sequence:rutile structure→coexistence of rutile and columbite phase→columbite ***(1-x)CoTiNb2O8-x ZnNb2O6 microwave dielectric ceramics,the addition of ZnNb2O6 content(x=0–1)led to the decrease ofer from 62.98 to *** a result of the high Q×?of ZnNb2O6 ceramics,the increase of ZnNb2O6 content also led to the lower sintering temperatures and the higher Q×?*** value was reduced from+108.04(x=0)to–49.31 ppm/℃(x=1).Among them,high density 0.5CoTiNb2O8-0.5ZnNb2O6 ceramics were obtained at 1175℃with excellent microwave dielectric properties of εr 39.2,Q×? 40013 GHz,and tf+3.57 ppm/℃.

关键词： solid-state reaction (1-x)CoT iN b2O8-x ZnN b2O6 ceramics crystal structure microwave dielectric property

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Utilizing Causal Network Markers to Identify Tipping Points ahead of Critical Transition

arXiv

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arXiv 2024年

作者： Bian, Shirui Wang, Zezhou Leng, Siyang Lin, Wei Shi, Jifan School of Mathematical Sciences Fudan University Shanghai200433 China Shanghai Center for Mathematical Sciences Fudan University Shanghai200433 China Research Institute of Intelligent Complex Systems Fudan University Shanghai200433 China Institute of AI and Robotics Academy for Engineering and Technology Fudan University Shanghai200433 China Shanghai Artificial Intelligence Laboratory Shanghai200232 China State Key Laboratory of Medical Neurobiology MOE Frontiers Center for Brain Science Fudan University Shanghai200032 China

Early-warning signals of delicate design are always used to predict critical transitions in complex systems, which makes it possible to render the systems far away from the catastrophic state by introducing timely interventions. Traditional signals including the dynamical network biomarker (DNB), based on statistical properties such as variance and autocorrelation of nodal dynamics, overlook directional interactions and thus have limitations in capturing underlying mechanisms and simultaneously sustaining robustness against noise perturbations. This paper therefore introduces a framework of causal network markers (CNMs) by incorporating causality indicators, which reflect the directional influence between variables. Actually, to detect and identify the tipping points ahead of critical transition, two markers are designed: CNM-GC for linear causality and CNM-TE for non-linear causality, as well as a functional representation of different causality indicators and a clustering technique to verify the system’s dominant group. Through demonstrations using benchmark models and real-world datasets of epileptic seizure, the framework of CNMs shows higher predictive power and accuracy than the traditional DNB indicator. It is believed that, due to the versatility and scalability, the CNMs are suitable for comprehensively evaluating the systems. The most possible direction for application includes the identification of tipping points in clinical disease. Copyright © 2024, The Authors. All rights reserved.

关键词： Autocorrelation

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Parameter estimation survey for multi-joint robot dynamic calibration case study

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science China(Information sciences) 2019年第10期62卷 102-116页

作者： Shaolin ZHANG Shuo WANG Fengshui JING Min TAN The State Key Laboratory of Management and Control for Complex Systems Institute of AutomationChinese Academy of Sciences University of Chinese Academy of Sciences CAS Center for Excellence in Brain Science and Intelligence Technology

Accurate model parameters are the basis of robot dynamics. Many linear and nonlinear models have been proposed to calibrate the inertial parameters and friction parameters of multi-joint ***, methods of choosing a model and calculating its parameters still have few summaries. This paper reviews typical linear/nonlinear models and different calculation methods for robot dynamic *** simulations, the features of different methods are analyzed, including torque error, parameter error, model adaptability, solution time, and anti-interference ability of the calibration results. Finally, an experiment performed on a six-degree-of-freedom industrial manipulator is used as an example to illustrate how to select the model for a specified robot. These comparisons and experiments provide references for the parameter calibration of multi-joint robots.

关键词： dynamic parameter calibration friction calibration robot dynamics industrial manipulator dynamic models

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The 110kV Live-Maintaining Robot Control System Design for Substation Equipment in complex Working Conditions 42

The 110kV Live-Maintaining Robot Control System Design for S...

引用

42nd Chinese Control Conference, CCC 2023

作者： Hu, Chenyu Chen, Xin Li, Chengyu Huang, Guangxian Zhou, Cheng Jian, Xu School of Automation China University of Geosciences Wuhan430074 China Hubei Key Laboratory of Advanced Control and Intelligent Automation for Complex Systems Wuhan430074 China School of Future Technology China University of Geosciences Wuhan430074 China State Grid Hubei Electric Power Co. Ltd. Xianning Power Supply Company Distribution Department Xianning437000 China State Grid Hubei Electric Power Co. Ltd Operations and Maintenance Department Xianning xian'An District Power Supply Company Xianning437000 China Equipment Technology Center State Grid Hubei Electric Power Co. Ltd. Electric Power Science Research Institute Wuhan430077 China Engineering Research Center of Intelligent Technology for Geo-Exploration Ministry of Education Wuhan430074 China

ISBN: (纸本)9789887581543

Live-maintaining work is essential for continuous power supply to the substation. To improve the safety and efficiency of live-maintaining work, this paper proposes an equipotential live-maintaining robot system suitable for 110kV voltage levels. Considering the narrow space, complex working conditions and strong electromagnetic interference in substations, binocular vision technology, manipulator trajectory planning algorithm based on time-energy optimization, high voltage electromagnetic shielding technology are utilized to develop the system, and the live-maintaining robot is successfully applied in actual substation. By accurately identifying and locating the joint bolts and insulator, the robot system can achieve equipotential live-disassemble, live-assemble the joint bolts within 18 minutes and live-clean insulator within 5 minutes, demonstrating its the effectiveness and practicability. © 2023 Technical Committee on Control Theory, Chinese Association of Automation.

关键词： Electromagnetic pulse

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Gain and phase type multipliers for structured feedback robustness

arXiv

引用

arXiv 2022年

作者： Ringh, Axel Mao, Xin Chen, Wei Qiu, Li Khong, Sei Zhen Department of Mathematical Sciences Chalmers University of Technology The University of Gothenburg GothenburgSE-412 96 Sweden Department of Electronic and Computer Engineering The Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong Department of Mechanics and Engineering Science State Key Laboratory for Turbulence and Complex Systems Peking University Beijing100871 China Independent Researcher

It is known that the stability of a feedback interconnection of two linear time-invariant systems implies that the graphs of the open-loop systems are quadratically separated. This separation is defined by an object known as the multiplier. The theory of integral quadratic constraints shows that the converse also holds under certain conditions. This paper establishes that if the feedback is robustly stable against certain structured uncertainty, then there always exists a multiplier that takes a corresponding form. In particular, if the feedback is robustly stable to certain gain-type uncertainty, then there exists a corresponding multiplier that is of phase-type, i.e., its diagonal blocks are zeros. These results build on the notion of phases of matrices and systems, which was recently introduced in the field of control. Similarly, if the feedback is robustly stable to certain phase-type uncertainty, then there exists a gain-type multiplier, i.e., its off-diagonal blocks are zeros. The results are meaningfully instructive in the search for a valid multiplier for establishing robust closed-loop stability, and cover the well-known small-gain and the recent small-phase theorems. Copyright © 2022, The Authors. All rights reserved.

关键词： Feedback

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Real-Time Marker Localization Learning for GelStereo Tactile Sensing

Real-Time Marker Localization Learning for GelStereo Tactile...

引用

IEEE International Conference on Robotics and Biomimetics

作者： Shujuan Liu Shaowei Cui Chaofan Zhang Yinghao Cai Shuo Wang University of Science and Technology Beijing State Key Laboratory of Management and Control for Complex Systems Institute of Automation Chinese Academy of Sciences Beijing China School of Artificial Intelligence University of Chinese Academy of Sciences Beijing China Institute of Automation Chinese Academy of Sciences Beijing China Center for Excellence in Brain Science Intelligence Technology Chinese Academy of Sciences Shanghai China

ISBN: (纸本)9781665481106

Visuotactile sensing technology is becoming more popular in tactile sensing, but the effectiveness of the existing marker detection/localization methods remains to be further explored. Instead of contour-based blob detection, this paper presents a learning-based marker localization network for GelStereo visuotactile sensing called Marknet. Specifically, the Marknet presents a grid regression architecture to incorporate the distribution of the GelStereo markers. Furthermore, a marker rationality evaluator (MRE) is modelled to screen suitable prediction results. The experimental results show that the Marknet combined with MRE achieves 93.90% precision for irregular markers in contact areas, which outperforms the traditional contour-based blob detection method by a large margin of 42.32%. Meanwhile, the proposed learning-based marker localization method can achieve better realtime performance beyond the blob detection interface provided by the OpenCV library through GPU acceleration, which we believe will lead to considerable perceptual sensitivity gains in various robotic manipulation tasks.

关键词： Location awareness Sensitivity Object detection Network architecture Predictive models Robot sensing systems Real-time systems

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