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Active learning with multifidelity modeling for efficient rare event simulation

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arXiv 2021年

作者： Dhulipala, Somayajulu L.N. Shields, Michael D. Spencer, Benjamin W. Bolisetti, Chandrakanth Slaughter, Andrew E. Labouré, Vincent M. Chakroborty, Promit Computational Mechanics and Materials Idaho National Laboratory Idaho FallsID83402 United States Department of Civil and Systems Engineering Johns Hopkins University BaltimoreMD21218 United States Advanced Reactor Technology and Design Idaho National Laboratory Idaho FallsID83402 United States Computational Frameworks Idaho National Laboratory Idaho FallsID83402 United States Reactor Physics Methods and Analysis Idaho National Laboratory Idaho FallsID83402 United States

While multifidelity modeling provides a cost-effective way to conduct uncertainty quantification with computationally expensive models, much greater efficiency can be achieved by adaptively deciding the number of required high-fidelity (HF) simulations, depending on the type and complexity of the problem and the desired accuracy in the results. We propose a framework for active learning with multifidelity modeling emphasizing the efficient estimation of rare events. Our framework works by fusing a low-fidelity (LF) prediction with an HF-inferred correction, filtering the corrected LF prediction to decide whether to call the high-fidelity model, and for enhanced subsequent accuracy, adapting the correction for the LF prediction after every HF model call. The framework does not make any assumptions as to the LF model type or its correlations with the HF model. In addition, for improved robustness when estimating smaller failure probabilities, we propose using dynamic active learning functions that decide when to call the HF model. We demonstrate our framework using several academic case studies and two finite element (FE) model case studies: estimating Navier-Stokes velocities using the Stokes approximation and estimating stresses in a transversely isotropic model subjected to displacements via a coarsely meshed isotropic model. Across these case studies, not only did the proposed framework estimate the failure probabilities accurately, but compared with either Monte Carlo or a standard variance reduction method, it also required only a small fraction of the calls to the HF model. © 2021, CC BY-NC-ND.

关键词： Uncertainty analysis

Chromosome-scale assembly and evolution of the tetraploid Salvia splendens (Lamiaceae) genome

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Horticulture Research 2021年第1期8卷 2721-2735页

作者： Kai-Hua Jia Hui Liu Ren-Gang Zhang Jie Xu Shan-Shan Zhou Si-Qian Jiao Xue-Mei Yan Xue-Chan Tian Tian-Le Shi Hang Luo Zhi-Chao Li Yu-Tao Bao Shuai Nie Jing-Fang Guo Ilga Porth Yousry AEl-Kassaby Xiao-Ru Wang Charles Chen Yves Van de Peer Wei Zhao Jian-Feng Mao Beijing Advanced Innovation Center for Tree Breeding by Molecular Design National Engineering Laboratory for Tree BreedingKey Laboratory of Genetics and Breeding in Forest Trees and Ornamental PlantsMinistry of EducationCollege of Biological Sciences and TechnologyBeijing Forestry UniversityBeijing 100083China Ori(Shandong)Gene Science and Technology Co. LtdWeifang 261000 ShandongChina Department des Sciences du Bois et de la Foret Facultede Foresteriede Geographie et GeomatiqueUniversite LavalQuebec CityQC G1V 0A6Canada Department of Forest and Conservation Sciences Faculty of ForestryUniversity of British ColumbiaVancouverBC V6T 1Z4Canada Department of Ecology and Environmental Science UmeåPlant Science CentreUmeåUniversitySE-90187 UmeåSweden Department of Biochemistry and Molecular Biology 246 Noble Research CenterOklahoma State UniversityStillwaterOKUSA Department of Plant Biotechnology and Bioinformatics Ghent UniversityGhentBelgium VIB Center for Plant Systems Biology 9052 GhentBelgium Centre for Microbial Ecology and Genomics Department of BiochemistryGenetics and Microbiology GeneticsUniversity of PretoriaPrivate Bag X20Pretoria 0028South Africa College of Horticulture Academy for Advanced Interdisciplinary StudiesNanjing Agricultural UniversityNanjing 210095China

Polyploidization plays a key role in plant evolution,but the forces driving the fate of homoeologs in polyploid genomes,i.e.,paralogs resulting from a whole-genome duplication(WGD)event,remain to be ***,we present a chromosome-scale genome assembly of tetraploid scarlet sage(Salvia splendens),one of the most diverse ornamental *** found evidence for three WGD events following an older WGD event shared by most eudicots(theγevent).A comprehensive,spatiotemporal,genome-wide analysis of homoeologs from the most recent WGD unveiled expression asymmetries,which could be associated with genomic rearrangements,transposable element proximity discrepancies,coding sequence variation,selection pressure,and transcription factor binding site *** observed differences between homoeologs may reflect the first step toward sub-and/or *** assembly provides a powerful tool for understanding WGD and gene and genome evolution and is useful in developing functional genomics and genetic engineering strategies for scarlet sage and other Lamiaceae species.

关键词： species evolution assembly

Author Correction: Ex vivo validation of magnetically actuated intravascular untethered robots in a clinical setting

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Communications engineering 2025年第1期4卷 1页

作者： Leendert-Jan W. Ligtenberg Nicole C. A. Rabou Wytze C. Duinmeijer Frank R. Halfwerk Jutta Arens Islam S. M. Khalil Constantinos Goulas H. Remco Liefers Roger Lomme Veronika Magdanz Anke Klingner Emily A. M. Klein Rot Colin H. E. Nijland Dorothee Wasserberg Pascal Jonkheijm Arturo Susarrey-Arce Michiel Warlé Department of Biomechanical Engineering University of Twente 7500 AE Enschede The Netherlands Technical Medical Centre University of Twente 7500 AE Enschede The Netherlands Department of Design Production and Management University of Twente 7500 AE Enschede The Netherlands Radboud University Medical Center 6525 GA Nijmegen The Netherlands Department of System Design Engineering University of Waterloo ON N2L 3G1 Waterloo Canada Department of Physics German University in Cairo New Cairo 11835 Egypt LipoCoat B.V. 7521 AG Enschede The Netherlands Laboratory of Biointerface Chemistry TechMed Centre University of Twente 7500 AE Enschede The Netherlands Mesoscale Chemical Systems MESA+ Institute University of Twente 7500 AE Enschede The Netherlands Department of Surgery Division of Vascular and Transplant Surgery Radboud University Medical Center Nijmegen Nijmegen The Netherlands

Toronto-3D: A large-scale mobile LiDAR dataset for semantic segmentation of urban roadways

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arXiv 2020年

作者： Tan, Weikai Qin, Nannan Ma, Lingfei Li, Ying Du, Jing Cai, Guorong Yang, Ke Li, Jonathan Department of Geography and Environmental Management University of Waterloo WaterlooONN2L 3G1 Canada Key Laboratory of Planetary Sciences Purple Mountain Observatory Chinese Academy of Sciences NanjingJS210033 China College of Computer Engineering Jimei University XiamenFJ 361021 China Department of Systems Design Engineering University of Waterloo WaterlooONN2L 3G1 Canada

Semantic segmentation of large-scale outdoor point clouds is essential for urban scene understanding in various applications, especially autonomous driving and urban high-definition (HD) mapping. With rapid developments of mobile laser scanning (MLS) systems, massive point clouds are available for scene understanding, but publicly accessible large-scale labeled datasets, which are essential for developing learning-based methods, are still limited. This paper introduces Toronto-3D, a large-scale urban outdoor point cloud dataset acquired by a MLS system in Toronto, Canada for semantic segmentation. This dataset covers approximately 1 km of point clouds and consists of about 78.3 million points with 8 labeled object classes. Baseline experiments for semantic segmentation were conducted and the results confirmed the capability of this dataset to train deep learning models effectively. Toronto-3D is released 1 to encourage new research, and the labels will be improved and updated with feedback from the research community. Copyright © 2020, The Authors. All rights reserved.

关键词： Semantic Segmentation

Super-Andreev reflection and longitudinal shift of pseudospin-1 fermions

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Physical Review B 2020年第23期101卷 235417-235417页

作者： Xiaolong Feng Ying Liu Zhi-Ming Yu Zhongshui Ma L. K. Ang Yee Sin Ang Shengyuan A. Yang Research Laboratory for Quantum Materials Singapore University of Technology and Design Singapore 487372 Singapore School of Materials Science and Engineering Hebei University of Technology Tianjin 300130 China Key Lab of Advanced Optoelectronic Quantum Architecture and Measurement (MOE) Beijing Key Lab of Nanophotonics & Ultrafine Optoelectronic Systems and School of Physics Beijing Institute of Technology Beijing 100081 China School of Physics Peking University Beijing 100871 China Science and Math Singapore University of Technology and Design Singapore 487372 Singapore

Novel fermions with a pseudospin-1 structure can be realized as emergent quasiparticles in condensed matter systems. Here, we investigate its unusual properties during the Andreev reflection at a normal-metal/ superconductor (NS) interface. We show that distinct from the previously studied pseudospin-1/2 and two-dimensional electron gas models, the pseudospin-1 fermions exhibit a strongly enhanced Andreev reflection probability, and remarkably, can be further tuned to approach perfect Andreev reflection with unit efficiency for all incident angles, exhibiting a previously unknown super-Andreev reflection effect. The super-Andreev reflection leads to perfect transparency of the NS interface that strongly promotes charge injection into the superconductor and directly manifests as a differential conductance peak which can be readily probed in experiment. Additionally, we find that sizable longitudinal shifts exist in the normal and Andreev reflections of pseudospin-1 fermions. Distinct from the pseudospin-1/2 case, the shift is always in the forward direction in the subgap regime, regardless of whether the reflection is of retro- or specular type.

关键词： Andreev reflection Transport phenomena 2-dimensional systems Superconductors Bogoliubov-de Gennes equations

A SSVEP-Based Wireless Retrieval Robot System

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A SSVEP-Based Wireless Retrieval Robot System

Chinese Automation Congress (CAC)

作者： Sihao Yang Tao Xue Shicheng Yan Zekun Tian Yuxin Zhang Qihuai Zhang Jintao Chen Zhongli Bai Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology Tianjin China Tianjin Key Laboratory for Control Theory and Applications in Complicated Systems Tianjin University of Technology Tianjin China

ISBN: (数字)9781728176871

ISBN: (纸本)9781728176888

The brain-computer interface (BCI) plays an important role in assisting the disabled in life support and entertainment. In this study, a wireless retrieval robot system for steady-state visual evoked potential (SSVEP) based BCI system was proposed. In order to improve the recognition accuracy and system stability of BCI system for subjects' instructions, in this study, offline and online experiments are used to study and solve the performance parameters, obstacle avoidance and retrieval performance of BCI respectively. In the offline experiment, 5 types of SSVEP data of 4 subjects were used. Based on CCA algorithm, the multi-channel fusion recognition accuracy, time window length (TWL), command activation margin and other aspects are studied. The optimal experimental parameters are determined. Online experiments are based on the optimal test parameters of offline experiments, 8 subjects were used to study the performance of obstacle avoidance and retrieval. The online experiments achieved an average accuracy of 87.89 ± 6.62% with an ITR of 23.6 ± 4.76 bit/min. Furthermore, the rate of success in grasping three kinds of different difficulty preset targets was 61.38%.

关键词： Electroencephalography Robots Electrodes Correlation coefficient Task analysis Visualization Liquid crystal displays

Geometric Filterless Photodetectors for Mid-infrared Spin Light

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arXiv 2022年

作者： Wei, Jingxuan Chen, Yang Li, Ying Li, Wei Xie, Junsheng Lee, Chengkuo Novoselov, Kostya S. Qiu, Cheng-Wei Department of Electrical and Computer Engineering National University of Singapore Singapore117583 Singapore CAS Key Laboratory of Mechanical Behaviour and Design of Materials Department of Precision Machinery and Precision Instrumentation University of Science and Technology of China Hefei230026 China Interdisciplinary Center for Quantum Information State Key Laboratory of Modern Optical Instrumentation ZJU-Hangzhou Global Scientific and Technological Innovation Center Zhejiang University Hangzhou310027 China International Joint Innovation Center Key Lab of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang Zhejiang University Haining314400 China GPL Photonics Lab State Key Laboratory of Applied Optics Changchun Institute of Optics Fine Mechanics and Physics Chinese Academy of Sciences Changchun130033 China Center for Intelligent Sensors and MEMS National University of Singapore Singapore117608 Singapore Institute for Functional Intelligent Materials National University of Singapore Singapore117544 Singapore

Free-space circularly polarized light (CPL) detection, requiring polarizers and waveplates, has been well established, while such spatial degree of freedom is unfortunately absent in integrated on-chip optoelectronics. So far, those reported filterless CPL photodetectors suffer from the intrinsic small discrimination ratio, vulnerability to the non-CPL field components, and low responsivity. Here, we report a distinct paradigm of geometric photodetectors in mid-infrared exhibiting colossal discrimination ratio, close-to-perfect CPL-specific response, a zero-bias responsivity of 392 V/W at room temperature, and a detectivity of ellipticity down to 0.03o Hz−1/2. Our approach employs plasmonic nanostructures array with judiciously designed symmetry, assisted by graphene ribbons to electrically read their near-field optical information. This geometry-empowered recipe for infrared photodetectors provides a robust, direct, strict, and high-quality solution to on-chip filterless CPL detection and unlocks new opportunities for integrated functional optoelectronic devices. Copyright © 2022, The Authors. All rights reserved.

关键词： Photodetectors

Distributed model predicted control of multi-agent systems with applications to multi-vehicle cooperation

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arXiv 2020年

作者： Bian, Yougang Du, Changkun Hu, Manjiang Liu, Haikuo State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle Engineering Hunan University Changsha410082 China Beijing Advanced Innovation Center for Intelligent Robots and Systems School of Mechatronical Engineering Beijing Institute of Technology Beijing100081 China School of Mechatronical Engineering Beijing Institute of Technology Beijing100081 China

This paper proposes a distributed model predicted control (DMPC) approach for consensus control of multi-agent systems (MASs) with linear agent dynamics and bounded control input constraints. Within the proposed DMPC framework, each agent exchanges assumed state trajectories with neighbors and solves a local open-loop optimization problem to obtain the optimal control input. In the optimization problem, a discrete-time consensus protocol is introduced into update law design for assumed terminal states, with which asymptotic consensus of assumed terminal states and recursive feasibility are rigorously proved. Together with the optimal cost function, an infinite series of cost-to-go functions is introduced into the design of a Lyapunov function, with which closed-loop asymptotic consensus is finally proved. Two applications including cooperation of autonomous underwater vehicles (AUVs) and connected and automated vehicles (CAVs) are used to validate the effectiveness of the proposed DMPC approach. Copyright © 2020, The Authors. All rights reserved.

关键词： Multi agent systems

design of audio to image cross-modal learning and generation based on single-layer CoPt spin-orbit torque devices

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Journal of Magnetism and Magnetic Materials 2025年 629卷

作者： Likun Qian Liu Yang Chao Zuo Ying Tao Wendi Li Fang Jin Huihui Li Kaifeng Dong School of Future Technology China University of Geosciences Wuhan 430074 China Hubei Key Laboratory of Advanced Control and Intelligent Automation for Complex Systems Wuhan 430074 China Engineering Research Center of Intelligent Technology for Geo-Exploration Ministry of Education Wuhan 430074 China School of Automation China University of Geosciences Wuhan 430074 China Wuhan Second Ship Design and Research Institute Wuhan 430064 China Beijing Superstring Academy of Memory Technology Beijing 100176 China

Despite remarkable achievements in neural network applications using spin–orbit torque (SOT) devices, current research predominantly focuses on unimodal classification tasks, while cross-modal learning tasks often suffer from suboptimal generation quality. To address this limitation, we employ generative adversarial networks (GANs) based on CoPt-SOT to achieve cross-modal learning and generation from speech to handwritten digit images. Initially, we explore the field-free switching characteristics of single-layer CoPt devices, developing spin-based implementations of Scaled Rectified Linear Unit (SReLu), Sigmoid, and Tanh neuronal functions. Simultaneously, we leverage the nonvolatile multistate characteristics of CoPt devices to realize excitatory-inhibitory synaptic plasticity. Subsequently, for the first time, we construct half-spin and full-spin GAN networks using these spin-based neurons and synapses, enabling cross-modal learning and generation between speech and image domains. Finally, we evaluate the performance of these networks through handwritten digit recognition tasks, achieving impressive recognition accuracies of 93.78 % and 88.61 % for half-spin and full-spin implementations, respectively. Notably, this work overcomes the existing bottleneck in SOT device applications, which have been largely confined to unimodal classification tasks, and demonstrates significant potential for expanding the scope of SOT-based technologies.

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