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arXiv 2020年

作者： Harirchi, Farshad Kim, Doohyun Khalil, Omar Liu, Sijia Elvati, Paolo Baranwal, Mayank Hero, Alfred Violi, Angela Department of Electrical Engineering and Computer Science University of Michigan Ann ArborMI48109–2125 United States Department of Mechanical Engineering University of Michigan Ann ArborMI48109–2125 United States Departments of Chemical Engineering Biomedical Engineering Macromolecular Science and Engineering Biophysics Program University of Michigan Ann ArborMI48109–2125 United States

A wide variety of real life complex networks are prohibitively large for modeling, analysis and control. Understanding the structure and dynamics of such networks entails creating a smaller representative network that preserves its relevant topological and dynamical properties. While modern machine learning methods have enabled identification of governing laws for complex dynamical systems, their inability to produce white-box models with sufficient physical interpretation renders such methods undesirable to domain experts. In this paper, we introduce a hybrid black-box, white-box approach for the sparse identification of the governing laws for complex, highly coupled dynamical systems with particular emphasis on finding the influential reactions in chemical reaction networks for combustion applications, using a data-driven sparse-learning technique. The proposed approach identifies a set of influential reactions using species concentrations and reaction rates, with minimal computational cost without requiring additional data or simulations. The new approach is applied to analyze the combustion chemistry of H2 and C3H8 in a constant-volume homogeneous reactor. The influential reactions determined by the sparse-learning method are consistent with the current kinetics knowledge of chemical mechanisms. Additionally, we show that a reduced version of the parent mechanism can be generated as a combination of the significantly reduced influential reactions identified at different times and conditions and that for both H2 and C3H8 fuel, the reduced mechanisms perform closely to the parent mechanisms as a function of the ignition delay time over a wide range of conditions. Our results demonstrate the potential of the sparse-learning approach as an effective and efficient tool for dynamical system analysis and reduction. The uniqueness of this approach as applied to combustion systems lies in the ability to identify influential reactions in specified conditions and times dur

关键词： Learning systems

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Thermally driven long-range magnon spin currents in yttrium iron garnet due to intrinsic spin Seebeck effect

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Physical Review B 2017年第18期96卷 180412(R)-180412(R)页

作者： Brandon L. Giles Zihao Yang John S. Jamison Juan M. Gomez-Perez Saül Vélez Luis E. Hueso Fèlix Casanova Roberto C. Myers Department of Materials Science and Engineering The Ohio State University Columbus Ohio 43210 USA Department of Electrical and Computer Engineering The Ohio State University Columbus Ohio 43210 USA CIC nanoGUNE 20018 Donostia-San Sebastian Basque Country Spain IKERBASQUE Basque Foundation for Science 48013 Bilbao Basque Country Spain Department of Physics The Ohio State University Columbus Ohio 43210 USA

The longitudinal spin Seebeck effect refers to the generation of a spin current when heat flows across a normal metal/magnetic insulator interface. Most explanations of the spin Seebeck effect use the interfacial temperature difference as the conversion mechanism between heat and spin fluxes. However, recent theoretical and experimental works claim that a magnon spin current is generated in the bulk of a magnetic insulator even in the absence of an interface. This is the so-called intrinsic spin Seebeck effect. Here, by utilizing a nonlocal spin Seebeck geometry, we provide additional evidence that the total magnon spin current in the ferrimagnetic insulator yttrium iron garnet (YIG) actually contains two distinct terms: one proportional to the gradient in the magnon chemical potential (pure magnon spin diffusion), and a second proportional to the gradient in magnon temperature (∇Tm). We observe two characteristic decay lengths for magnon spin currents in YIG with distinct temperature dependences: a temperature independent decay length of ∼10μm consistent with earlier measurements of pure (∇Tm=0) magnon spin diffusion, and a longer decay length ranging from about 20μm around 250 K and exceeding 80μm at 10 K. The coupled spin-heat transport processes are modeled using a finite element method revealing that the longer-range magnon spin current is attributable to the intrinsic spin Seebeck effect (∇Tm≠0), whose length scale increases at lower temperatures in agreement with our experimental data.

关键词： Magnons Spin Seebeck effect Spin diffusion Spin waves Ferrimagnets Finite-element method Transport techniques

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Physical Review B 2019年第7期99卷 075430-075430页

作者： Matthew E. Trusheim Noel H. Wan Kevin C. Chen Christopher J. Ciccarino Johannes Flick Ravishankar Sundararaman Girish Malladi Eric Bersin Michael Walsh Benjamin Lienhard Hassaram Bakhru Prineha Narang Dirk Englund Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA John A. Paulson School of Engineering and Applied Sciences Harvard University Cambridge Massachusetts 02138 USA Department of Chemistry and Chemical Biology Harvard University Cambridge Massachusetts 02138 USA Department of Materials Science and Engineering Rensselaer Polytechnic Institute Troy New York 12180 USA College of Nanoscale Science and Engineering State University of New York Polytechnic Institute 257 Fuller Road Albany New York 12203 USA

We report on quantum emission from Pb-related color centers in diamond following ion implantation and high-temperature vacuum annealing. First-principles calculations predict a negatively charged Pb-vacancy (PbV) center in a split-vacancy configuration, with a zero-phonon transition around 2.4 eV. Cryogenic photoluminescence measurements performed on emitters in nanofabricated pillars reveal several transitions, including a prominent doublet near 520 nm. The splitting of this doublet, 5.7 THz, exceeds that reported for other group-IV centers. These observations are consistent with the PbV center, which is expected to have a combination of narrow optical transitions and stable spin states, making it a promising system for quantum network nodes.

关键词： Atomic orbital Density functional theory Electronic structure of atoms & molecules Photoemission Quantum memories Quantum repeaters Single- and few-photon ionization & excitation

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Gratings on porous silicon structures for sensing applications

Gratings on porous silicon structures for sensing applicatio...

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Conference on Lasers and Electro-Optics, CLEO 2009

作者： Liscidini, M. Wei, X. Kang, C. Rong, G. Retterer, S.T. Patrini, M. Sipe, J.E. Weiss, S.M. Department of Physics University of Toronto 60 St. George St Toronto M5S 1A7 ON Canada Department of Electrical Engineering and Computer Science Vanderbilt University Nashville TN 37235 United States Interdisciplinary Graduate Program in Materials Science Vanderbilt University Nashville TN 37235 United States Center for Nanophase Materials Sciences Oak Ridge National Laboratory Oak Ridge TN 37831 United States CNISM and Dipartimento di Fisica 'A. Volta' Università degli Studi di Pavia via Bassi 6 27100 Pavia Italy

We investigate the use of gratings on porous silicon structures for sensing applications. Examples of two classes of systems are studied: grating-coupled waveguide biosensors, and diffraction-based biosensors. © ... 详细信息

ISBN: (纸本)9781557528698

关键词： Biosensors

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Lattice-mismatched semiconductor heterostructures

arXiv

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arXiv 2018年

作者： Liu, Dong Cho, Sang June Seo, Jung-Hun Kim, Kwangeun Kim, Munho Shi, Jian Yin, Xin Choi, Wonsik Zhang, Chen Kim, Jisoo Baboli, Mohadeseh A. Park, Jeongpil Bong, Jihye Lee, In-Kyu Gong, Jiarui Mikael, Solomon Ryu, Jae Ha Mohseni, Parsian K. Li, Xiuling Gong, Shaoqin Wang, Xudong Ma, Zhenqiang Department of Electrical and Computer Engineering University of Wisconsin –Madison MadisonWI53706 United States Department of Materials Science and Engineering University of Wisconsin –Madison MadisonWI United States Department of Electrical and Computer Engineering University of Illinois – Urbana Champaign ChampaignIL61820 United States Microsystems Engineering and NanoPower Research Laboratories Rochester Institute of Technology RochesterNY14623 United States Department of Biomedical Engineering University of Wisconsin –Madison MadisonWI United States

Semiconductor heterostructure is a critical building block for modern semiconductor devices. However, forming semiconductor heterostructures of lattice-mismatch has been a great challenge for several decades. Epitaxial growth is infeasible to form abrupt heterostructures with large lattice-mismatch while mechanical-thermal bonding results in a high density of interface defects and therefore severely limits device applications. Here we show an ultra-thin oxide-interfaced approach (named as "grafting") for the successful formation of lattice-mismatched semiconductor heterostructures. Following the depiction of a theory on the role of interface oxide in forming the heterostructures, we describe experimental demonstrations of Ge/Si (diamond lattices), Si/GaAs (zinc blende lattice), GaAs/GaN (hexagon lattice), and Si/GaN heterostructures. Extraordinary electrical performances in terms of ideality factor, current on/off ratio, and reverse breakdown voltage are measured from p-n diodes fabricated from the four types of heterostructures, significantly outperforming diodes derived from other methods. Our demonstrations indicate the versatility of the ultra-thin-oxide-interface approach in forming lattice-mismatched heterostructures, open up a much larger possibility for material combinations for heterostructures, and pave the way toward broader applications in electronic and optoelectronic realms. Copyright © 2018, The Authors. All rights reserved.

关键词： Heterojunctions

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Annealing of semiconductor core optical fibers

Annealing of semiconductor core optical fibers

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Specialty Optical Fibers, SOF 2012

作者： Gupta, N. McMillen, C. Singh, R. Podila, R. Rao, A.M. Hawkins, T. Foy, P. Morris, S. Poole, K.F. Zhu, L. Ballato, J. Rice, R. Holcombe Department of Electrical and Computer Engineering Clemson University Clemson SC 29634 United States Center for Silicon Nanoelectronics Clemson University Clemson SC 29634 United States Department of Chemistry Clemson University Clemson SC 29634 United States Department of Physics and Astronomy Clemson University Clemson SC 29634 United States School of Materials Science and Engineering Clemson University Clemson SC 29634 United States Dreamcatchers Consulting Simi Valley CA 93065 United States

Ex-situ rapid photothermal annealing is shown, through X-ray diffraction, Raman spectroscopy and Schottky diodes, to enhance the structural homogeneity of silicon optical fibers by increasing local crystallinity, thus... 详细信息

ISBN: (纸本)9781557529466

关键词： Optical fibers

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Robust and High-Performance Electrodes Via Crumpled Au-CNT Forests for Stretchable Supercapacitors

SSRN

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SSRN 2020年

作者： Zhou, Yihao Cao, Changyong Cao, Yunteng Han, Qiwei Parker, Charles Glass, Jeffrey T. Department of Mechanical Engineering & Materials Science Duke University DurhamNC27708 United States Departments of Mechanical Engineering Electrical & Computer Engineering Michigan State University East LansingMI48824 United States Department of Civil and Environmental Engineering Massachusetts Institute of Technology CambridgeMA02139 United States Department of Chemistry Duke University DurhamNC27708 United States Department of Electrical & Computer Engineering Duke University DurhamNC27708 United States

Stretchable supercapacitors based on vertically aligned nanotubes or nanowires have attracted considerable attention because of their improved robustness and electrochemical performance under large and repeated deformations. However, it is still challenging to maintain the low electric resistance of stretchable electrodes of such a stretchable supercapacitor under extremely large strains due to the variation of the contacts between individual nanotubes/wires. Here, we develop and demonstrate a robust and high-performance stretchable electrode based on crumpled Au coated CNT forest (Au-CNT-forest), which significantly increases the conductivity of the original CNT-forest electrode while maintaining its unique crumpled hierarchical structures. Experimental measurements show that the resistance of the Au-CNT- forest electrode is around one order magnitude lower than that of a pure CNT-forest electrode and is comparable to that of a conventional thin film electrode. The biaxially crumpled Au-CNT-forest electrode demonstrates nearly identical electrochemical performance at all the measured charge/discharge rates (i.e., from 0.5 to 80 mA cm-2) under different strain conditions (i.e., from 0% to 800%), which can not be achieved by a pure CNT-forest electrode. The as-prepared symmetric supercapacitor with crumpled Au-CNT forest electrodes demonstrates a maximum specific capacitance of ~ 6 mF cm-2 at the scan rate of 40 mA cm-2 under different strains, exhibiting superior mechanical and electrochemical stability. This research demonstrates a facile process to fabricate highly stretchable supercapacitors based on vertically aligned nanotubes or nanowires for achieving exceptional and robust electrochemical performance. © 2020, The Authors. All rights reserved.

关键词： Supercapacitor

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Subdiffusive wave transport and weak localization transition in three-dimensional stealthy hyperuniform disordered systems

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Physical Review B 2022年第6期105卷 064204-064204页

作者： F. Sgrignuoli S. Torquato L. Dal Negro Department of Electrical and Computer Engineering & Photonics Center Boston University 8 Saint Mary's Street Boston Massachusetts 02215 USA Department of Chemistry Department of Physics Princeton Institute for the Science and Technology of Materials and Program in Applied and Computational Mathematics Princeton University Princeton New Jersey 08540 USA Division of Material Science and Engineering Boston University 15 Saint Mary's Street Brookline Massachusetts 02446 USA Department of Physics Boston University 590 Commonwealth Avenue Boston Massachusetts 02215 USA

The purpose of this work is to understand the fundamental connection between structural correlations and light localization in three-dimensional (3D) open scattering systems of finite size. We numerically investigate the transport of vector electromagnetic waves scattered by resonant electric dipoles spatially arranged in 3D space by stealthy hyperuniform disordered point patterns. Three-dimensional stealthy hyperuniform disordered systems are engineered with different structural correlation properties determined by their degree of stealthiness χ. Such fine control of exotic states of amorphous matter enables the systematic design of optical media that interpolate in a tunable fashion between uncorrelated random structures and crystalline materials. By solving the electromagnetic multiple scattering problem using Green's matrix spectral method, we establish a transport phase diagram that demonstrates a distinctive transition from a diffusive to a weak localization regime beyond a critical scattering density that depends on χ. The transition is characterized by studying the Thouless number and the spectral statistics of the scattering resonances. In particular, by tuning the χ parameter, we demonstrate large spectral gaps and suppressed subradiant proximity resonances, facilitating light localization. Moreover, consistently with previous studies, our results show a region of the transport phase diagram where the investigated scattering systems become transparent. Our work provides a systematic description of the transport and weak localization properties of light in stealthy hyperuniform structures and motivates the engineering of photonic systems with enhanced light-matter interactions for applications to both classical and quantum devices.

关键词： Anderson localization Light-matter interaction Mesoscopics Photonics Scattering theory Weak localization Metamaterials

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DCGAN-based Medical Image Augmentation to Improve ELM Classification Performance

DCGAN-based Medical Image Augmentation to Improve ELM Classi...

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IEEE International Conference on Communication, Networks and Satellite (ComNetSat)

作者： Rando Noor Akhmad Setiawan Adhistya Erna Permanasari Riries Rulaningtyas Andriyan Bayu Suksmono Imas Sukaesih Sitanggang Dept. of Electrical and Information Engineering Universitas Gadjah Mada Yogyakarta Indonesia Dept. of Physics Universitas Airlangga Biomedical Engineering Program Surabaya Indonesia School of Electrical Engineering and Informatics Institut Teknologi Bandung Bandung Indonesia Department of Computer Science IPB University Bogor Indonesia

ISBN: (数字)9781665460309

ISBN: (纸本)9781665460316

Cervical cancer is one of the deadliest diseases in women. One of the cervical cancer screening methods is pap smear method. However, using a pap smear method to detect cervical cancer takes a long time for a pathologist to diagnose. Hence, a rapid development of medical computerization for early detection to get the results quickly is needed. This paper proposes synthetic data augmentation by using Deep Convolutional Generative Adversarial Network (DCGAN) to increase number of pap smear samples in dataset. Gray Level Co-occurrence Matrix (GLCM) is employed to extract features from dataset. Classification of 3 classes which are Adenocarcinoma, High-Grade Squamous Intraepithelial Lesion (HSIL), and Squamous Cell Carcinoma (SCC) is conducted using Extreme Learning Machine (ELM). The result shows that the addition of synthetic data improves the performance of ELM with the accuracy of 90%. This accuracy is better than the accuracy of ELM using only the original dataset which is 85%.

关键词： Satellites Extreme learning machines Medical services Feature extraction Generative adversarial networks Entropy Lesions

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Measurement of the conduction band spin-orbit splitting in WSe2 and WS2 monolayers

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Physical Review B 2023年第24期107卷 245407-245407页

作者： Lei Ren Cedric Robert Hanan Dery Minhao He Pengke Li Dinh Van Tuan Pierre Renucci Delphine Lagarde Takashi Taniguchi Kenji Watanabe Xiaodong Xu Xavier Marie Université de Toulouse INSA-CNRS-UPS LPCNO 135 Avenue Rangueil 31077 Toulouse France Department of Electrical and Computer Engineering University of Rochester Rochester New York 14627 USA Department of Physics and Astronomy University of Rochester Rochester New York 14627 USA Department of Physics University of Washington Seattle Washington 98195 USA International Center for Materials Nanoarchitectonics National Institute for Materials Science Tsukuba Ibaraki 305-0044 Japan Research Center for Functional Materials National Institute for Materials Science Tsukuba Ibaraki 305-0044 Japan Department of Materials Science and Engineering University of Washington Seattle Washington 98195 USA

We have investigated charge tunable devices based on WSe2 and WS2 monolayers encapsulated in hexagonal boron nitride. In addition to the well-known radiative recombination of neutral and charged excitons, stationary photoluminescence measurements highlight a weaker-intensity optical transition that appears when the monolayer is electrostatically doped with electrons. We have carried out a detailed characterization of this photoluminescence line based on its doping dependence, its variation as a function of the optical excitation power, its polarization characteristics, and its g factor measured under longitudinal magnetic field. We interpret this luminescence peak as an impurity-assisted radiative recombination of the intervalley negatively charged exciton (triplet trion). In addition to the standard direct recombination, the triplet trion has a second recombination channel triggered by elastic scattering off the short-range impurity potential. The energy difference between the emitted photons from these two possible recombination processes of the same triplet trion is simply the single-particle conduction band spin-orbit splitting Δc. We measure Δc=12±0.5 meV for the WSe2 monolayer and Δc=12±1 meV for the WS2 monolayer. These results demonstrate the importance of second-order exciton recombination processes in transition-metal dichalcogenide structures.

关键词： Excitons Luminescence Spin-orbit coupling Trions 2-dimensional systems Transition metal dichalcogenides

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