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Impact of nanopillars on phonon dispersion and thermal conductivity of silicon membranes

Nanoscale 2023年第5期15卷 2248-2253页

作者： Anufriev, Roman Ohori, Daisuke Wu, Yunhui Yanagisawa, Ryoto Jalabert, Laurent Samukawa, Seiji Nomura, Masahiro Institute of Industrial Science The University of Tokyo Tokyo153-8505 Japan Institute of Fluid Science Tohoku University Sendai980-8577 Japan The University of Tokyo Tokyo153-8505 Japan Advanced Institute for Materials Research Tohoku University Sendai980-8577 Japan Department of Electrical and Computer Engineering National Yang Ming Chiao Tung University Hsinchu300 Taiwan Joint Research Center of National Yang Ming Chiao Tung University Tohoku University National Yang Ming Chiao Tung University Hsinchu300 Taiwan

The performance of silicon-based thermoelectric energy generators is limited by the high thermal conductivity of silicon. Theoretical works have long proposed reducing the thermal conductivity by resonant phonon modes in nanopillars placed on the surface of silicon films. However, these predictions have never been confirmed due to the difficulty in the nanofabrication and measurements of such nanoscale systems. In this work, we report on the fabrication and measurements of silicon films with nanopillars as small as 12 nm in diameter. Our Brillouin light scattering spectroscopy experiments revealed that nanopillars indeed host resonant phonon modes. Yet, our thermal measurements using the micro time-domain thermoreflectance technique showed only a statistically insignificant difference between the thermal properties of silicon membranes with and without nanopillars. Results of this work contrast with the predictions of a substantial reduction in the thermal conductivity due to nanopillars and suggest refining the simulations to account for realistic experimental conditions. © 2023 The Royal Society of Chemistry.

关键词： Phonons

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Parallel Repetition of k-Player Projection Games

arXiv

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arXiv 2023年

作者： Bhangale, Amey Braverman, Mark Khot, Subhash Liu, Yang P. Minzer, Dor Department of Computer Science and Engineering University of California Riverside United States Department of Computer Science Princeton University United States Department of Computer Science Courant Institute of Mathematical Sciences New York University United States School of Mathematics Institute for Advanced Study PrincetonNJ United States Department of Mathematics Massachusetts Institute of Technology United States

We study parallel repetition of k-player games where the constraints satisfy the projection property. We prove exponential decay in the value of a parallel repetition of projection games with value less than 1. ©...

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Classification of Infant Sleep/Wake States: Cross-Attention among Large Scale Pretrained Transformer Networks using Audio, ECG, and IMU Data

arXiv

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arXiv 2023年

作者： Chang, Kai Chieh Hasegawa-Johnson, Mark McElwain, Nancy L. Islam, Bashima Department of Electrical and Computer Engineering University of Illinois Urbana Champaign United States Beckman Institute for Advanced Science and Technology University of Illinois Urbana-Champaign United States Department of Human Development and Family Studies University of Illinois Urbana-Champaign United States Department of Electrical and Computer Engineering Worcester Polytechnic Institute United States

Infant sleep is critical to brain and behavioral development. Prior studies on infant sleep/wake classification have been largely limited to reliance on expensive and burdensome polysomnography (PSG) tests in the laboratory or wearable devices that collect single-modality data. To facilitate data collection and accuracy of detection, we aimed to advance this field of study by using a multi-modal wearable device, LittleBeats (LB), to collect audio, electrocardiogram (ECG), and inertial measurement unit (IMU) data among a cohort of 28 infants. We employed a 3-branch (audio/ECG/IMU) large scale transformer-based neural network (NN) to demonstrate the potential of such multi-modal data. We pretrained each branch independently with its respective modality, then finetuned the model by fusing the pretrained transformer layers with cross-attention. We show that multi-modal data significantly improves sleep/wake classification (accuracy = 0.880), compared with use of a single modality (accuracy = 0.732). Our approach to multi-modal mid-level fusion may be adaptable to a diverse range of architectures and tasks, expanding future directions of infant behavioral research. © 2023, CC BY.

关键词： Electrocardiograms

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Imaging atomic-scale chemistry from fused multi-modal electron microscopy

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npj Computational Materials 2022年第1期8卷 164-171页

作者： Jonathan Schwartz Zichao Wendy Di Yi Jiang Alyssa J.Fielitz Don-Hyung Ha Sanjaya D.Perera Ismail El Baggari Richard D.Robinson Jeffrey A.Fessler Colin Ophus Steve Rozeveld Robert Hovden Department of Materials Science and Engineering University of MichiganAnn ArborMIUSA Mathematics and Computer Science Division Argonne National LaboratoryLemontILUSA Advanced Photon Source Facility Argonne National LaboratoryLemontILUSA Dow Chemical Co. MidlandMIUSA Department of Material Science and Engineering Cornell UniversityIthacaNew YorkUSA School of Integrative Engineering Chung-Ang UniversitySeoulRepublic of Korea Department of Physics Cornell UniversityIthacaNYUSA The Rowland Institute at Harvard CambridgeMAUSA Department of Electrical Engineering and Computer Science University of MichiganAnn ArborMIUSA National Center for Electron Microscopy Lawrence Berkeley National LaboratoryMolecular FoundryBerkeleyCAUSA Applied Physics Program University of MIchiganAnn ArborMIUnited States

Efforts to map atomic-scale chemistry at low doses with minimal noise using electron microscopes are fundamentally limited by inelastic ***,fused multi-modal electron microscopy offers high signal-to-noise ratio(SNR)recovery of material chemistry at nano-and atomic-resolution by coupling correlated information encoded within both elastic scattering(high-angle annular dark-field(HAADF))and inelastic spectroscopic signals(electron energy loss(EELS)or energy-dispersive x-ray(EDX)).By linking these simultaneously acquired signals,or modalities,the chemical distribution within nanomaterials can be imaged at significantly lower doses with existing detector *** many cases,the dose requirements can be reduced by over one order of *** high SNR recovery of chemistry is tested against simulated and experimental atomic resolution data of heterogeneous nanomaterials.

关键词： materials chemistry fused

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Enabling Smart Cities with Cognition Based Intelligent Route Decision in Vehicles Empowered with Deep Extreme Learning Machine

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computers, Materials & Continua 2021年第1期66卷 141-156页

作者： Dildar Hussain Muhammad Adnan Khan Sagheer Abbas Rizwan Ali Naqvi Muhammad Faheem Mushtaq Abdur Rehman Afrozah Nadeem School of Computational Sciences Korea Institute for Advanced StudySeoul02455Korea Department of Computer Science Lahore Garrison UniversityLahore54000Pakistan School of Computer Science National College of Business Administration&EconomicsLahore54000Pakistan Department of Unmanned Vehicle Engineering Sejong UniversitySeoul05006Korea Department of Information Technology Khwaja Fareed University of Engineering and Information TechnologyRahim Yar Khan64200Pakistan

The fast-paced growth of artificial intelligence provides unparalleled opportunities to improve the efficiency of various industries,including the transportation *** worldwide transport departments face many obstacles following the implementation and integration of different vehicle *** of these tasks is to ensure that vehicles are autonomous,intelligent and able to grow their repository of *** learning has recently been implemented in wireless networks,as a major artificial intelligence branch,to solve historically challenging problems through a data-driven *** this article,we discuss recent progress of applying machine learning into vehicle networks for intelligent route decision and try to focus on this emerging *** Extreme Learning Machine(DELM)framework is introduced in this article to be incorporated in vehicles so they can take human-like *** present GPS compatibility issues make it difficult for vehicles to take real-time decisions under certain *** leads to the concept of vehicle controller making *** proposed DELM based system for self-intelligent vehicle decision makes use of the cognitive memory to store route *** overcomes inadequacy of the current in-vehicle route-finding technology and its *** the relevant route-related information for the ride will be provided to the user based on its *** the DELM method,a high degree of precision in smart decision taking with a minimal error rate is *** investigation,it has been observed that proposed framework has the highest accuracy rate with 70%of training(1435 samples)and 30%of validation(612 samples).Simulation results validate the intelligent prediction of the proposed method with 98.88%,98.2%accuracy during training and validation respectively.

关键词： DELM ANN IoT feedforward route decision prediction smart city

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Printable Aligned Single-Walled Carbon Nanotube Film with Outstanding Thermal Conductivity and Electromagnetic Interference Shielding Performance

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Nano-Micro Letters 2022年第11期14卷 143-156页

作者： Zhihui Zeng Gang Wang Brendan F.Wolan Na Wu Changxian Wang Shanyu Zhao Shengying Yue Bin Li Weidong He Jiurong Liu Joseph W.Lyding Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials Ministry of EducationSchool of Materials Science and EngineeringShandong UniversityShandongJinan 250061People’s Republic of China Department of Electrical and Computer Engineering Beckman Institute for Advanced Science and TechnologyUniversity of Illinois at Urbana-ChampaignUrbanaIL 61801USA Department of Chemistry Swiss Federal Institute of Technology in Zurich(ETH Zürich)8092 ZurichSwitzerland School of Materials Science and Engineering Nanyang Technological University50 Nanyang AvenueSingapore 639798Singapore Empa Swiss Federal Laboratories for Materials Science and TechnologyÜberland Strasse 1298600 DübendorfSwitzerland Institute for Advanced Technology Shandong UniversityJinan 250061People’s Republic of China

Ultrathin,lightweight,and flexible aligned single-walled carbon nanotube(SWCNT)films are fabricated by a facile,environmentally friendly,and scalable printing *** aligned pattern and outstanding intrinsic properties render“metal-like”thermal conductivity of the SWCNT films,as well as excellent mechanical strength,flexibility,and ***,the aligned cellular microstructure promotes the electromagnetic interference(EMI)shielding ability of the SWCNTs,leading to excellent shielding effectiveness(SE)of~39 to 90 dB despite a density of only~0.6 g cm^(−3) at thicknesses of merely 1.5-24μm,*** ultrahigh thickness-specific SE of 25693 dB mm^(−1) and an unprecedented normalized specific SE of 428222 dB cm^(2)g^(−1) are accomplished by the freestanding SWCNT films,significantly surpassing previously reported shielding *** addition to an EMI SE greater than 54 dB in an ultra-broadband frequency range of around 400 GHz,the films demonstrate excellent EMI shielding stability and reliability when subjected to mechanical deformation,chemical(acid/alkali/organic solvent)corrosion,and high-/low-temperature *** novel printed SWCNT films offer significant potential for practical applications in the aerospace,defense,precision components,and smart wearable electronics industries.

关键词： Aligned film Single-walled carbon nanotube Lightweight Flexible Thermal conductivity Electromagnetic interference shielding

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静态无源超构声呐实现声束动态扫描

引用

Science Bulletin 2023年第17期68卷 1862-1866页

作者：刘京京王未赵澄宇周永强张晗梁彬仇成伟程建春 Key Laboratory of Modern Acoustics(Ministry of Education) Institute of AcousticsDepartment of PhysicsCollaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing 210093China Department of Electrical and Computer Engineering National University of SingaporeSingapore 117583Singapore Key Laboratory of Noise and Vibration Institute of AcousticsChinese Academy of SciencesBeijing 100190China

声束的连续动态扫描在超声成像、水下目标定位和声呐通信等诸多领域发挥关键作用.传统方法通常依赖于发射装置的机械扫描或有源相控阵的波束整形来实时调控声束的空间指向性,存在成本高、尺寸大、主动控制系统复杂而精准操控困难等问题... 详细信息

声束的连续动态扫描在超声成像、水下目标定位和声呐通信等诸多领域发挥关键作用.传统方法通常依赖于发射装置的机械扫描或有源相控阵的波束整形来实时调控声束的空间指向性,存在成本高、尺寸大、主动控制系统复杂而精准操控困难等问题.本文提出并构建了一种基于无源声学超表面的紧凑型静态声呐器件,无需主动控制和机械移动,仅在单一声源的作用下即可实现声束的动态扫描操控.这种新型声呐器件由具有深度亚波长厚度的二值化振幅编码单元组合而成,能够将单一声源发射的梳状频率谱转化为具有相同频率和空间间隔的声焦点阵列,从而引入频率梯度这一新的声波操控自由度,并通过时空声干涉效应产生可连续旋转的动态扫描声束.实验结果验证了所设计超构声呐的高速、宽角度声束扫描性能.此外,通过与传统的相位梯度调控技术结合,该机制还可以对扫描声束的空间形态进行任意的调节.这种基于静态无源超构声呐的声束动态扫描机制为声波的时空调控开辟了新的研究范式,并有望在水下对抗、超声诊疗等重要领域产生实际应用价值.

关键词：有源相控阵相位梯度声束动态扫描声呐干涉效应机械扫描连续旋转

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A Unified Approach for Binary-Class and Multi-Class Data Augmented Generation

A Unified Approach for Binary-Class and Multi-Class Data Aug...

引用

Artificial Intelligence (CAI), IEEE Conference on

作者： Frederic Rizk Rodrigue Rizk Dominick Rizk Patrick Rizk Chee-Hung Henry Chu The Center for Advanced Computer Studies University of Louisiana at Lafayette Lafayette LA U.S.A. Department of Computer Science University of South Dakota Vermillion SD U.S.A. Department of Electrical Engineering and Computer Science The Catholic University of America Washington DC U.S.A. Department of Mechanical Engineering University of Quebec at Trois-Rivières Drummondville QC Canada The Center for Advanced Computer Studies Informatics Research Institute University of Louisiana at Lafayette Lafayette LA U.S.A.

ISBN: (数字)9798350354096

ISBN: (纸本)9798350354102

Deep neural networks excel in a wide range of tasks but require diverse datasets to prevent overfitting. Overfitting occurs when a network fits training data too precisely, leading to poor generalization. Data Augmentation is often used to mitigate overfitting aiming at enlarging and improving the quality of training datasets, facilitating the construction of superior deep learning models. MAGAN algorithm emerges as an innovative approach that functions as a Meta-Analysis of Generative Adversarial Networks (GANs). MAGAN harnesses the latent space capabilities of GANs to confront the challenges presented by binary-class, multi-class, grayscale, and RGB images, effectively covering a wide spectrum of scenarios. In this paper, we propose the use of MAGAN algorithm for binary-class and multi-class data augmented generation. We also undertake an in-depth experimental analysis, evaluating the performance of the proposed MAGAN-based approach in comparison to two alternative baseline scenarios: one without any augmentation and another utilizing a conventional augmentation method. To gauge the effectiveness of the proposed technique, we employed diverse classification metrics, including accuracy, loss, precision, recall, F1-score, and the confusion matrix. Our results demonstrate that the proposed approach surpasses the other two scenarios achieving improvements in terms of accuracy by a factor of x1.15 and x1.03, respectively. This underscores the significant advantages of harnessing MAGAN, a meta-analysis of GANs, for data augmentation across a range of image types and classification tasks.

关键词： Deep learning Measurement Accuracy Training data Artificial neural networks Gray-scale Data augmentation

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Query lower bounds for log-concave sampling

arXiv

引用

arXiv 2023年

作者： Chewi, Sinho Dios Pont, Jaume de Li, Jerry Lu, Chen Narayanan, Shyam School of Mathematics at Institute for Advanced Study United States Department of Mathematics at University of California Los Angeles United States Microsoft Research United States Department of Mathematics at Massachusetts Institute of Technology United States Department of Electrical Engineering and Computer Science at Massachusetts Institute of Technology United States

Log-concave sampling has witnessed remarkable algorithmic advances in recent years, but the corresponding problem of proving lower bounds for this task has remained elusive, with lower bounds previously known only in dimension one. In this work, we establish the following query lower bounds: (1) sampling from strongly log-concave and log-smooth distributions in dimension d ≥ 2 requires Ω(log κ) queries, which is sharp in any constant dimension, and (2) sampling from Gaussians in dimension d (hence also from general log-concave and log-smooth distributions in dimension d) requires Ω(min(e √κ log d, d)) queries, which is nearly sharp for the class of Gaussians. Here κ denotes the condition number of the target distribution. Our proofs rely upon (1) a multiscale construction inspired by work on the Kakeya conjecture in geometric measure theory, and (2) a novel reduction that demonstrates that block Krylov algorithms are optimal for this problem, as well as connections to lower bound techniques based on Wishart matrices developed in the matrix-vector query literature. Copyright © 2023, The Authors. All rights reserved.

关键词： Number theory

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On Security-Constrained Bidding of Shared Transportation Hubs for Renewable Fuels and Refined Oil Participating Within Energy, Regulation and Pipeline Logistics Markets

On Security-Constrained Bidding of Shared Transportation Hub...

引用

IEEE Student Conference on Electric Machines and Systems

作者： Shengshi Wang Hongyi Li Danji Huang Kun Li Shichang Cui Xiaomeng Ai Jiakun Fang Jinyu Wen State Key Laboratory of Advanced Electromagnetic Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan China School of Engineering Cardiff University Cardiff UK Department of Electrical and Computer Engineering Iowa State University Ames United States Department of Electrical and Computer Engineering University of Macau Macau China PetroChina ShenZhen New Energy Research Institute Co. Ltd. Shenzhen China

ISBN: (数字)9798350366945

ISBN: (纸本)9798350366952

This paper investigates the security-constrained bidding strategy of the emerging shared transportation hubs for renewable fuels and refined oil (STH-RRs) participating within energy, regulation and pipeline logistics markets. Firstly, to excavate more flexible capability for the power system as well as to increase the revenue of the STH-RR operation company, the model for STH-RR participating in regulation market is established. Secondly, the security-constrained two-stage bidding model is first proposed for STH-RRs to balance the revenue across energy, regulation and pipeline logistics markets. Particularly, to guarantee secure operation of STH-RRs and meet the delivery demand, the rigorous multi-product transportation constraints are considered in both stages. Case studies based on the modified real-world multi-product pipelines in South China validate the proposed method, with the revenue and turnover increase of 14% and 4.7%, respectively, compared with conventional methods.

关键词： Renewable energy sources Uncertainty Oils Pipelines Transportation Regulation Fuels Frequency control Logistics Testing

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