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arXiv 2022年

作者： Zhang, Yichen Gao, Yuxiang Gao, Xue-Jian Lei, Shiming Ni, Zhuoliang Oh, Ji Seop Huang, Jianwei Yue, Ziqin Zonno, Marta Gorovikov, Sergey Hashimoto, Makoto Lu, Donghui Denlinger, Jonathan D. Birgeneau, Robert J. Kono, Junichiro Wu, Liang Law, Kam Tuen Morosan, Emilia Yi, Ming Department of Physics and Astronomy Rice University HoustonTX77005 United States Department of Physics Hong Kong University of Science and Technology Clear Water Bay Hong Kong Department of Physics and Astronomy University of Pennsylvania PhiladelphiaPA19104 United States Department of Physics University of California BerkeleyCA94720 United States Applied Physics Graduate Program Smalley-Curl Institute Rice University HoustonTX77005 United States Canadian Light Source Inc. 44 Innovation Boulevard SaskatoonSKS7N 2V3 Canada Stanford Synchrotron Radiation Lightsource SLAC National Accelerator Laboratory 2575 Sand Hill Road Menlo ParkCA94025 United States Advanced Light Source Lawrence Berekeley National Laboratory BerkeleyCA94720 United States Materials Science Division Lawrence Berekeley National Laboratory BerkeleyCA94720 United States Department of Electrical and Computer Engineering Rice University HoustonTX77005 United States Department of Materials Science and Nanoengineering Rice University HoustonTX77005 United States

Kramers nodal lines (KNLs) have recently been proposed theoretically as a special type of Weyl line degeneracy connecting time-reversal invariant momenta. KNLs are robust to spin orbit coupling and are inherent to all non-centrosymmetric achiral crystal structures, leading to unusual spin, magneto-electric, and optical properties. However, their existence in in real quantum materials has not been experimentally established. Here we gather the experimental evidence pointing at the presence of KNLs in SmAlSi, a non-centrosymmetric metal that develops incommensurate spin density wave order at low temperature. Using angle-resolved photoemission spectroscopy, density functional theory calculations, and magneto-transport methods, we provide evidence suggesting the presence of KNLs, together with observing Weyl fermions under the broken inversion symmetry in the paramagnetic phase of SmAlSi. We discuss the nesting possibilities regarding the emergent magnetic orders in SmAlSi. Our results provide a solid basis of experimental observations for exploring correlated topology in SmAlSi. © 2022, CC BY-NC-SA.

关键词： Temperature

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The economics of utility-scale portable energy storage systems in a high-renewable grid

arXiv

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arXiv 2020年

作者： He, Guannan Michalek, Jeremy Kar, Soummya Chen, Qixin Zhang, Da Whitacre, Jay F. MIT Energy Initiative Massachusetts Institute of Technology CambridgeMA United States Institute of Energy Environment and Economy Tsinghua University Beijing China MIT Joint Program on the Science and Policy of Global Change Massachusetts Institute of Technology CambridgeMA United States Department of Electrical and Computer Engineering Carnegie Mellon University PittsburghPA United States Department of Electrical Engineering Tsinghua University Beijing China Department of Engineering and Public Policy Carnegie Mellon University PittsburghPA United States Department of Mechanical Engineering Carnegie Mellon University PittsburghPA United States Department of Materials Science and Engineering Carnegie Mellon University PittsburghPA United States

Summary: Battery storage is expected to play a crucial role in the low-carbon transformation of energy systems. The deployment of battery storage in the power gird, however, is currently severely limited by its low economic viability, which results from not only high capital costs but also the lack of flexible and efficient utilization schemes and business models. Making utility-scale battery storage portable through trucking unlocks its capability to provide various on-demand services. We introduce the potential applications of utility-scale portable energy storage and investigate its economics in California using a spatiotemporal decision model that determines the optimal operation and transportation schedules of portable storage. We show that mobilizing energy storage can increase its life-cycle revenues by 70% in some areas and improve renewable energy integration by relieving local transmission congestion. The life-cycle revenue of spatiotemporal arbitrage can fully compensate for the costs of portable energy storage system in several regions in California, including San Diego and the San Francisco Bay Area. Copyright © 2020, The Authors. All rights reserved.

关键词： Life cycle

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Interplay of Purcell Effect, Stimulated Emission, and Leaky Modes in the Photoluminescence Spectra of Microsphere Cavities

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Physical Review Applied 2019年第5期11卷 051001-051001页

作者： Ching-Hang Chien Shang-Hsuan Wu Trong Huynh-Buu Ngo Yia-Chung Chang Research Center for Applied Sciences Academia Sinica Taipei 115 Taiwan Nano Science and Technology Program TIGP Academia Sinica Taipei 115 Taiwan Department of Engineering and System Science National Tsing Hua University Hsinchu 300 Taiwan Department of Electrical and Computer Engineering University of Texas at Austin USA Department of Electrical and Computer Engineering University of Alberta Edmonton Alberta T6G 2V4 Canada

A theoretical model for describing the emission spectra of microsphere cavities is presented and its predictions of detailed line shapes of emission spectra associated with whispering gallery modes (WGMs) of various orders in ZnO microspheres (MSs) are verified experimentally by photoluminescence (PL) spectroscopy. The interplay of the Purcell effect, quality factor, and leaky modes in spontaneous and stimulated emission spectra related to WGMs of all orders is revealed. The key success of the theory is based on the expansion of the full Green’s function of the MS in terms of all possible resonance modes in complex frequency space, which allows incorporation of contributions from leaky modes, stimulated emission processes, and the Purcell effect. We show that the spontaneous emission spectrum calculated according to Mie theory (without the Purcell effect) is dominated by the contribution of leaky modes, while the spontaneous and stimulated emission enhanced by the Purcell effect is responsible for the main WGM resonance peaks observed experimentally. It is found that the stimulated emission peaks are doubly enhanced by their respective mode quality factor Q: one factor from the Purcell effect and the other factor from the photon number derived from the rate equation. After combining all these effects, the theory can provide a quantitative description of fine features of both TE and TM modes (including higher-order modes) observed in the PL spectra of ZnO MSs. Surprisingly, it is found that for ZnO MS with a diameter larger than 5 μm, the PL emission spectrum is dominated by higher-order modes. The quantitative understanding of the interplay of these emission mechanisms should prove useful for optimizing the performance of light-emitting devices based on microresonators.

关键词： Cavity quantum electrodynamics Lasers Light-matter interaction Optical pumping Photonics Semiconductor quantum optics Spontaneous emission Whispering gallery mode resonators

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Acoustic Power Divider Based on Compressibility-Near-Zero Propagation

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Physical Review Applied 2020年第2期14卷 024057-024057页

作者： Hussein Esfahlani Matthew S. Byrne Andrea Alù Electrical Engineering Institute École Polytechnique Fedérale de Lausanne (EPFL) CH-1015 Lausanne Switzerland Department of Electrical & Computer Engineering The University of Texas at Austin Austin Texas 78712 USA Photonics Initiative Advanced Science Research Center New York New York 10031 USA Kymeta Corporation Redmond Washington 98052 USA Naval Surface Warfare Center Carderock Division West Bethesda Maryland 20817 USA Physics Program Graduate Center New York New York 10016 USA

Materials with properties that can be described by a near-zero index of refraction have received significant attention in the fields of electromagnetics, optics, and acoustics, due to their extraordinary capabilities in wave manipulation. It was recently demonstrated theoretically and experimentally that acoustic waves could manifest near-zero-index propagation based on the effective compressibility of a waveguide channel approaching zero. In turn, this allows tunneling of acoustic waves with nearly infinite wavelength (or equivalently, uniform phase) when the channel cross section is much larger than the feeding lines. Here, we show that these concepts can be leveraged to realize an acoustic power divider and multiplexer offering tunneling of sound to an arbitrary number of output ports, with phase shifts equal to 0° or 180° and robust response to variations in the port position. We present analytical and numerical models describing the properties of this device and study limitations and trade-offs that occur in the presence of losses as the device size is scaled.

关键词： Acoustic metamaterials Acoustic wave phenomena Acoustics

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GeoT: A Geometry-aware Transformer for Reliable Molecular Property Prediction and Chemically Interpretable Representation Learning

arXiv

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arXiv 2021年

作者： Kwak, Bumju Park, Jiwon Kang, Taewon Jo, Jeonghee Lee, Byunghan Yoon, Sungroh Recommendation Team Kakao Corporation Gyeonggi13529 Korea Republic of LG Chem Seoul07795 Korea Republic of Interdisciplinary Program in Artificial Intelligence Seoul National University Seoul08826 Korea Republic of Daejeon34141 Korea Republic of Institute of New Media and Communications Seoul National University Seoul08826 Korea Republic of Department of Electronic Engineering Seoul National University of Science and Technology Seoul01811 Korea Republic of Department of Electrical and Computer Engineering Seoul National University Seoul08826 Korea Republic of Artificial Intelligence Institute Seoul National University Seoul08826 Korea Republic of

In recent years, molecular representation learning has emerged as a key area of focus in various chemical tasks. However, many existing models fail to fully consider the geometric information of molecular structures, resulting in less intuitive representations. Moreover, the widely used message-passing mechanism is limited to provide the interpretation of experimental results from a chemical perspective. To address these challenges, we introduce a novel Transformer-based framework for molecular representation learning, named the Geometry-aware Transformer (GeoT). GeoT learns molecular graph structures through attention-based mechanisms specifically designed to offer reliable interpretability, as well as molecular property prediction. Consequently, GeoT can generate attention maps of interatomic relationships associated with training objectives. In addition, GeoT demonstrates comparable performance to MPNN-based models while achieving reduced computational complexity. Our comprehensive experiments, including an empirical simulation, reveal that GeoT effectively learns the chemical insights into molecular structures, bridging the gap between artificial intelligence and molecular sciences. © 2021, CC BY.

关键词： Geometry

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BigNeuron: a resource to benchmark and predict performance of algorithms for automated tracing of neurons in light microscopy datasets

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Nature methods 2023年第6期20卷 824-835页

作者： Linus Manubens-Gil Zhi Zhou Hanbo Chen Arvind Ramanathan Xiaoxiao Liu Yufeng Liu Alessandro Bria Todd Gillette Zongcai Ruan Jian Yang Miroslav Radojević Ting Zhao Li Cheng Lei Qu Siqi Liu Kristofer E Bouchard Lin Gu Weidong Cai Shuiwang Ji Badrinath Roysam Ching-Wei Wang Hongchuan Yu Amos Sironi Daniel Maxim Iascone Jie Zhou Erhan Bas Eduardo Conde-Sousa Paulo Aguiar Xiang Li Yujie Li Sumit Nanda Yuan Wang Leila Muresan Pascal Fua Bing Ye Hai-Yan He Jochen F Staiger Manuel Peter Daniel N Cox Michel Simonneau Marcel Oberlaender Gregory Jefferis Kei Ito Paloma Gonzalez-Bellido Jinhyun Kim Edwin Rubel Hollis T Cline Hongkui Zeng Aljoscha Nern Ann-Shyn Chiang Jianhua Yao Jane Roskams Rick Livesey Janine Stevens Tianming Liu Chinh Dang Yike Guo Ning Zhong Georgia Tourassi Sean Hill Michael Hawrylycz Christof Koch Erik Meijering Giorgio A Ascoli Hanchuan Peng Institute for Brain and Intelligence Southeast University Nanjing China. Microsoft Corporation Redmond WA USA. Tencent AI Lab Bellevue WA USA. Computing Environment and Life Sciences Directorate Argonne National Laboratory Lemont IL USA. Kaya Medical Seattle WA USA. University of Cassino and Southern Lazio Cassino Italy. Center for Neural Informatics Structures and Plasticity Krasnow Institute for Advanced Study George Mason University Fairfax VA USA. Faculty of Information Technology Beijing University of Technology Beijing China. Beijing International Collaboration Base on Brain Informatics and Wisdom Services Beijing China. Nuctech Netherlands Rotterdam the Netherlands. Janelia Research Campus Howard Hughes Medical Institute Ashburn VA USA. Department of Electrical and Computer Engineering University of Alberta Edmonton Alberta Canada. Ministry of Education Key Laboratory of Intelligent Computation and Signal Processing Anhui University Hefei China. Paige AI New York NY USA. Scientific Data Division and Biological Systems and Engineering Division Lawrence Berkeley National Lab Berkeley CA USA. Helen Wills Neuroscience Institute and Redwood Center for Theoretical Neuroscience UC Berkeley Berkeley CA USA. RIKEN AIP Tokyo Japan. Research Center for Advanced Science and Technology (RCAST) The University of Tokyo Tokyo Japan. School of Computer Science University of Sydney Sydney New South Wales Australia. Texas A&M University College Station TX USA. Cullen College of Engineering University of Houston Houston TX USA. Graduate Institute of Biomedical Engineering National Taiwan University of Science and Technology Taipei Taiwan. National Centre for Computer Animation Bournemouth University Poole UK. PROPHESEE Paris France. Department of Neuroscience Columbia University New York NY USA. Mortimer B. Zuckerman Mind Brain Behavior Institute Columbia University New York NY USA. Department of Computer Science Northern Illinois Universit

BigNeuron is an open community bench-testing platform with the goal of setting open standards for accurate and fast automatic neuron tracing. We gathered a diverse set of image volumes across several species that is representative of the data obtained in many neuroscience laboratories interested in neuron tracing. Here, we report generated gold standard manual annotations for a subset of the available imaging datasets and quantified tracing quality for 35 automatic tracing algorithms. The goal of generating such a hand-curated diverse dataset is to advance the development of tracing algorithms and enable generalizable benchmarking. Together with image quality features, we pooled the data in an interactive web application that enables users and developers to perform principal component analysis, t-distributed stochastic neighbor embedding, correlation and clustering, visualization of imaging and tracing data, and benchmarking of automatic tracing algorithms in user-defined data subsets. The image quality metrics explain most of the variance in the data, followed by neuromorphological features related to neuron size. We observed that diverse algorithms can provide complementary information to obtain accurate results and developed a method to iteratively combine methods and generate consensus reconstructions. The consensus trees obtained provide estimates of the neuron structure ground truth that typically outperform single algorithms in noisy datasets. However, specific algorithms may outperform the consensus tree strategy in specific imaging conditions. Finally, to aid users in predicting the most accurate automatic tracing results without manual annotations for comparison, we used support vector machine regression to predict reconstruction quality given an image volume and a set of automatic tracings.

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Plasmonic sensors on invisible substrates

Plasmonic sensors on invisible substrates

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Bio-Optics: Design and Application, BODA 2019

作者： Misbah, Ibrahim Shih, Wei-Chuan Department of Electrical and Computer Engineering University of Houston 4800 Calhoun Rd HoustonTX77004 United States Department of Biomedical Engineering University of Houston 4800 Calhoun Rd HoustonTX77004 United States Program of Materials Science and Engineering University of Houston 4800 Calhoun Rd HoustonTX77004 United States Department of Chemistry University of Houston 4800 Calhoun Rd HoustonTX77004 United States

Gold nanodisks array with minimal effect from the glass substrates have been fabricated using nanosphere lithography and HF undercutting. The undercut substrates have blueshifted plasmonic resonance with higher bulk r... 详细信息

ISBN: (纸本)9781943580545

关键词： Glass substrates

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Author Correction: Macroscopic transition metal dichalcogenides monolayers with uniformly high optical quality

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Nature communications 2023年第1期14卷 6241页

作者： Qiuyang Li Adam Alfrey Jiaqi Hu Nathanial Lydick Eunice Paik Bin Liu Haiping Sun Yang Lu Ruoyu Wang Stephen Forrest Hui Deng Department of Physics University of Michigan Ann Arbor MI 48109 USA. Applied Physics Program University of Michigan Ann Arbor MI 48109 USA. Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI 48109 USA. Michigan Center for Materials Characterization College of Engineering University of Michigan Ann Arbor MI 48109 USA. Department of Physics University of Michigan Ann Arbor MI 48109 USA. dengh@umich.edu. Applied Physics Program University of Michigan Ann Arbor MI 48109 USA. dengh@umich.edu.

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Local Convolutions Cause an Implicit Bias towards High Frequency Adversarial Examples

arXiv

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arXiv 2020年

作者： Caro, Josue Ortega Ju, Yilong Pyle, Ryan Dey, Sourav Brendel, Wieland Anselmi, Fabio Patel, Ankit B. Department of Neuroscience Baylor College of Medicine HoustonTX77030 United States Quantitative and Computational Bioscience Program Baylor College of Medicine HoustonTX70030 United States Department of Computer Science Rice University HoustonTX77005 United States Manifold AI United States University of Tübingen Germany Department of Electrical and Computer Engineering Rice University HoustonTX70005 United States

Adversarial Attacks are still a significant challenge for neural networks. Recent efforts has shown that adversarial perturbations typically contain high-frequency features, but the root cause of this phenomenon remains unknown. Inspired by theoretical work on linear full-width convolutional models, we hypothesize that convolutional operations with localized kernels are implicitly biased to learn high frequency features, and that this is one of the root causes of high frequency adversarial examples. To test this hypothesis, we analyzed the impact of different choices of linear and nonlinear architectures on the implicit bias of the learned features and the adversarial perturbations, in spatial and frequency domains. We find that, independently of the training dataset, convolutional operations have higher frequency adversarial attacks compared to other architectural parametrizations, and this phenomenon is exacerbated with stronger locality of the convolutional kernels. The explanation for the kernel size dependence involves the Fourier Uncertainty Principle: a spatially-limited (local in the space domain) filter cannot also be frequency-limited (local in the frequency domain). Using larger convolution kernel sizes or avoiding convolutions (e.g. by using Vision Transformers or MLP-style architectures) significantly reduces this high frequency bias. Looking forward, our work strongly suggests that understanding and controlling the implicit bias of architectures will be essential for achieving adversarial robustness. © 2020, CC BY.

关键词： Convolution

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Holographic optical tweezers assisted imaging spectroscopy

Holographic optical tweezers assisted imaging spectroscopy

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Optical Manipulation and Its Applications, OMA 2019 - Part of Biophotonics Congress: Optics in the Life sciences Congress 2019

作者： Rakhshandehroo, Mohsen Shih, Wei-Chuan Department of Electrical and Computer Engineering University of Houston 4800 Calhoun Rd HoustonTX77004 United States Department of Biomedical Engineering University of Houston 4800 Calhoun Rd HoustonTX77004 United States Program of Materials Science and Engineering University of Houston 4800 Calhoun Rd HoustonTX77004 United States Department of Chemistry University of Houston 4800 Calhoun Rd HoustonTX77004 United States

Holographic optical tweezers (HOT) is an effective means for optical manipulation. Herein we demonstrate its integration with imaging spectroscopy for biological and biomedical applications. © 2019 The Author(s).

ISBN: (纸本)9781943580545

关键词： Holography

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