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Identification of earthquake induced structural damage based on synchroextracting transform

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Earthquake engineering and engineering Vibration 2024年第2期23卷 475-487页

作者： Roshan Kumar Gaurav Kumar Wei Zhao Arvind R Yadav Gang Yu Jayendra Kumar Evans Amponsah department of Electronic and Information Technology Miami College of Henan UniversityHenan 475004China alliance University Alliance College of Engineering and DesignBanglore 562106India department of Electronics and Comm Parul UniversityVadodra 391760India School of electrical engineering University of JinanJinan 250022China department of Electronics and Comm NIT JamshedpurJamshedpur 831014India department of Civil engineering Kwame Nkrumah University of Science and TechnologyKumasi 10959Ghana

Several popular time-frequency techniques,including the Wigner-Ville distribution,smoothed pseudo-Wigner-Ville distribution,wavelet transform,synchrosqueezing transform,Hilbert-Huang transform,and Gabor-Wigner transform,are investigated to determine how well they can identify damage to *** this work,a synchroextracting transform(SET)based on the short-time Fourier transform is proposed for estimating post-earthquake structural *** performance of SET for artificially generated signals and actual earthquake signals is examined with existing *** other tested techniques,SET improves frequency resolution to a great extent by lowering the influence of smearing along the time-frequency ***,interpretation and readability with the proposed method are improved,and small changes in the time-varying frequency characteristics of the damaged buildings are easily detected through the SET method.

关键词： cross-term damage detection earthquake signal synchroextracting transform time-frequency

Free-electron crystals for enhanced X-ray radiation

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Light(Science & Applications) 2024年第7期13卷 1299-1309页

作者： Lee Wei Wesley Wong Xihang Shi Aviv Karnieli Jeremy Lim Suraj Kumar Sergio Carbajo Ido Kaminer Liang Jie Wong School of electrical and Electronic engineering Nanyang Technological University50 Nanyang AvenueSingapore 639798Singapore. Solid State Institute and Faculty of electrical and Computer engineering Technion–Israel Institute of TechnologyHaifa 3200003Israel. School of electrical engineering Fleischman Faculty of EngineeringTel Aviv UniversityTel Aviv 69978Israel department of Applied Physics Stanford UniversityStanfordCA 94305USA. Science Mathematics and TechnologySingapore University of Technology and Design8 Somapah RoadSingapore 487372Singapore. electrical and Computer engineering department UCLA420 WestwoodLos AngelesCA 90095USA. Physics and Astronomy department UCLA475 Portola PlazaLos AngelesCA 90095USA. SLAC National Accelerator Laboratory Stanford University2575 Sand Hill RoadMenlo ParkCA 94025USA

Bremsstrahlung—the spontaneous emission of broadband radiation from free electrons that are deflected by atomic nuclei—contributes to the majority of X-rays emitted from X-ray tubes and used in applications ranging from medical imaging to semiconductor chip ***,we show that the bremsstrahlung intensity can be enhanced significantly—by more than three orders of magnitude—through shaping the electron wavefunction to periodically overlap with atoms in crystalline ***,we show how to shape the bremsstrahlung X-ray emission pattern into arbitrary angular emission profiles for purposes such as unidirectionality and ***,we find that these enhancements and shaped emission profiles cannot be attributed solely to the spatial overlap between the electron probability distribution and the atomic centers,as predicted by the paraxial and nonrecoil theory for free electron light *** work highlights an unprecedented regime of free electron light emission where electron waveshaping provides multi-dimensional control over practical radiation processes like *** results pave the way towards greater versatility in table-top X-ray sources and improved fundamental understanding of quantum electron-light interactions.

关键词： overlap attributed arbitrary

Machine-learned wearable sensors for real-time hand-motion recognition: toward practical applications

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National Science Review 2024年第2期11卷 231-263页

作者： Kyung Rok Pyun Kangkyu Kwon Myung Jin Yoo Kyun Kyu Kim Dohyeon Gong Woon-Hong Yeo Seungyong Han Seung Hwan Ko department of Mechanical engineering Seoul National University IEN Center for Human-Centric Interfaces and engineering Institute for Electronics and NanotechnologyGeorgia Institute of Technology School of electrical and Computer engineering Georgia Institute of Technology department of Chemical engineering Stanford University department of Mechanical engineering Ajou University George W.Woodruff School of Mechanical engineering Georgia Institute of Technology Institute of Advanced Machinery and Design(SNU-IAMD) Seoul National University

Soft electromechanical sensors have led to a new paradigm of electronic devices for novel motion-based wearable applications in our daily lives. However, the vast amount of random and unidentified signals generated by complex body motions has hindered the precise recognition and practical application of this technology. Recent advancements in artificial-intelligence technology have enabled significant strides in extracting features from massive and intricate data sets, thereby presenting a breakthrough in utilizing wearable sensors for practical applications. Beyond traditional machine-learning techniques for classifying simple gestures, advanced machine-learning algorithms have been developed to handle more complex and nuanced motion-based tasks with restricted training data sets. Machine-learning techniques have improved the ability to perceive, and thus machine-learned wearable soft sensors have enabled accurate and rapid human-gesture recognition, providing real-time feedback to users. This forms a crucial component of future wearable electronics, contributing to a robust human–machine interface. In this review, we provide a comprehensive summary covering materials, structures and machine-learning algorithms for hand-gesture recognition and possible practical applications through machine-learned wearable electromechanical sensors.

关键词： wearable sensor soft electronics artificial intelligence machine learning human–machine interfaces gesture recognition

Quick Line Outage Identification in Urban Distribution Grids via Smart Meters

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CSEE Journal of Power and Energy Systems 2022年第4期8卷 1074-1086页

作者： Yizheng Liao Yang Weng Cin-Woo Tan Ram Rajagopal department of Civil and Environmental engineering Stanford UniversityStanfordCA94305USA School of electrical Computingand Energy EngineeringArizona State UniversityTempeAZ85287USA

The growing integration of distributed energy resources(DERs)in distribution grids raises various reliability issues due to DER's uncertain and complex *** large-scale DER penetration in distribution grids,traditional outage detection methods,which rely on customers report and smart meters'“last gasp”signals,will have poor performance,because renewable generators and storage and the mesh structure in urban distribution grids can continue supplying power after line *** address these challenges,we propose a datadriven outage monitoring approach based on the stochastic time series analysis with a theoretical ***,we prove via power flow analysis that dependency of time-series voltage measurements exhibits significant statistical changes after line *** makes the theory on optimal change-point detection suitable to identify line ***,existing change point detection methods require post-outage voltage distribution,which are unknown in distribution ***,we design a maximum likelihood estimator to directly learn distribution parameters from voltage *** prove the estimated parameters-based detection also achieves optimal performance,making it extremely useful for fast distribution grid outage ***,since smart meters have been widely installed in distribution grids and advanced infrastructure(e.g,PMU)has not widely been available,our approach only requires voltage magnitude for quick outage *** results show highly accurate outage identification in eight distribution grids with 17 configurations with and without DERs using smart meter data.

关键词： Power distribution network outage detection outage identification voltage measurement change point detection graphical model

Multi-dimensional band structure spectroscopy in the synthetic frequency dimension

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Light(Science & Applications) 2023年第7期12卷 1425-1433页

作者： Dali Cheng Eran Lustig Kai Wang Shanhui Fan Ginzton Laboratory and department of electrical engineering Stanford UniversityStanfordCA94305USA department of Physics McGll UniversityMontrealQC H3A 2T8Canada

The concept of synthetic dimensions in photonics provides a versatile platform in exploring multi-dimensional *** of these physics are characterized by band structures in more than one *** efforts on band structure measurements in the photonic synthetic frequency dimension however are limited to either onedimensional Brillouin zones or one-dimensional subsets of multi-dimensional Billouin *** we theoretically propose and experimentally demonstrate a method to fully measure multi-dimensional band structures in the synthetic frequency *** use a single photonic resonator under dynamical modulation to create a multidimensional synthetic frequency *** show that the band structure of such a lattice over the entire multidimensional Brillouin zone can be measured by introducing a gauge potential into the lattice *** this method,we perform experimental measurements of two-dimensional band structures of a Hermitian and a non-Hermitian *** measurements reveal some of the general properties of point-gap topology of the non-Hermitian Hamiltonian in more than one *** results demonstrate experimental capabilities to fully characterize high-dimensional physical phenomena in the photonic synthetic frequency dimension.

关键词： resonator synthetic dimensional

Spatiotemporal Input Control:Leveraging Temporal Variation in Network Dynamics

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IEEE/CAA Journal of Automatica Sinica 2022年第4期9卷 635-651页

作者： Yihan Lin Jiawei Sun Guoqi Li Gaoxi Xiao Changyun Wen Lei Deng H.Eugene Stanley the department of Precision Instrument Tsinghua University the department of Bio-engineering Stanford University IEEE the Institute of Automation Chinese Academy of Sciences the School of electrical and Electronic engineering Nanyang Technological University department of Physics and Center for Polymer Studies Boston University

The number of available control sources is a limiting factor to many network control tasks.A lack of input sources can result in compromised controllability and/or sub-optimal network performance,as noted in engineering applications such as the smart *** mechanism can be explained by a linear timeinvariant model,where structural controllability sets a lower bound on the number of required *** by the ubiquity of time-varying topologies in the real world,we propose the strategy of spatiotemporal input control to overcome the source-related limit by exploiting temporal variation of the network *** theoretically prove that under this regime,the required number of sources can always be reduced to *** is further shown that the cost of control depends on two hyperparameters,the numbers of sources and intervals,in a trade-off *** a demonstration,we achieve controllability over a complex network resembling the nervous system of Caenorhabditis elegans using as few as 6%of the sources predicted by a static control *** example underlines the potential of utilizing topological variation in complex network control problems.

关键词： Complex network complex system control theory complex system optimization temporal network time-varying system

Fast Bayesian optimization of Needle-in-a-Haystack problems using zooming memory-based initialization (ZoMBI)

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npj Computational Materials 2023年第1期9卷 1543-1555页

作者： Alexander E.Siemenn Zekun Ren Qianxiao Li Tonio Buonassisi department of Mechanical engineering Massachusetts Institute of TechnologyCambridgeMAUSA department of electrical and Computer engineering Singapore-MIT Alliance for Research and TechnologySingaporeSingapore Xinterra SingaporeSingapore department of Mathematics National University of SingaporeSingaporeSingapore Institute for Functional Intelligent Materials National University of SingaporeSingaporeSingapore

Needle-in-a-Haystack problems exist across a wide range of applications including rare disease prediction,ecological resource management,fraud detection,and material property optimization.A Needle-in-a-Haystack problem arises when there is an extreme imbalance of optimum conditions relative to the size of the ***,current state-of-the-art optimization algorithms are not designed with the capabilities to find solutions to these challenging multidimensional Needle-in-a-Haystack problems,resulting in slow convergence or pigeonholing into a local *** this paper,we present a Zooming Memory-Based Initialization algorithm,entitled ZoMBI,that builds on conventional Bayesian optimization principles to quickly and efficiently optimize Needle-in-a-Haystack problems in both less time and fewer *** ZoMBI algorithm demonstrates compute time speed-ups of 400×compared to traditional Bayesian optimization as well as efficiently discovering optima in under 100 experiments that are up to 3×more highly optimized than those discovered by similar methods.

关键词： optimization problems extreme

Polychromatic metasurfaces for complete control of phase and polarization in the mid-infrared

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Light(Science & Applications) 2023年第11期12卷 2266-2268页

作者： You Zhou Jonathan A.Fan department of electrical engineering Stanford UniversityStanfordCA 94305USA

Multifunctional metasurfaces based on wavelength-decoupled supercells are experimentally demonstrated,enabling new regimes of optical control for arbitrary orthogonal polarizations at different wavelengths.

关键词： polarization surfaces phase

Distributed Majorization-Minimization for Laplacian Regularized Problems

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IEEE/CAA Journal of Automatica Sinica 2019年第1期6卷 45-52页

作者： Jonathan Tuck David Hallac Stephen Boyd IEEE the department of electrical engineering Stanford University

We consider the problem of minimizing a block separable convex function(possibly nondifferentiable, and including constraints) plus Laplacian regularization, a problem that arises in applications including model fitting, regularizing stratified models, and multi-period portfolio optimization. We develop a distributed majorization-minimization method for this general problem, and derive a complete, self-contained, general,and simple proof of convergence. Our method is able to scale to very large problems, and we illustrate our approach on two applications, demonstrating its scalability and accuracy.

关键词： Convex optimization distributed optimization graphical networks Laplacian regularization