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arXiv 2024年

作者： Venkatesan, Balaji Guan, Syu-You Chang, Jen-Te Chiu, Shiang-Bin Yang, Po-Yuan Su, Chih-Chuan Chang, Tay-Rong Raju, Kalaivanan Sankar, Raman Fongchaiya, Somboon Chu, Ming-Wen Chang, Chia-Seng Chang, Guoqing Lin, Hsin Del Maestro, Adrian Kao, Ying-Jer Chuang, Tien-Ming Department of Physics National Taiwan University Taipei10617 Taiwan Nano Science and Technology Program Taiwan International Graduate Program Academia Sinica National Taiwan University Taipei11529 Taiwan Institute of Physics Academia Sinica Taipei11529 Taiwan Department of Physics National Cheng-Kung University Tainan701 Taiwan Center for Condensed Matter Sciences National Taiwan University Taipei10617 Taiwan Molecular Science and Technology Program Taiwan International Graduate Program Academia Sinica Taipei11529 Taiwan Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University 21 Nanyang Link 637371 Singapore Department of Physics and Astronomy University of Tennessee KnoxvilleTN37996 United States Institute for Advanced Materials & Manufacturing University of Tennessee KnoxvilleTN37996 United States Min H. Kao Department of Electrical Engineering and Computer Science University of Tennessee KnoxvilleTN37996 United States Center for Quantum Science and Technology National Taiwan University Taipei10607 Taiwan

Electronic liquid crystal (ELC) phases are spontaneous symmetry breaking states believed to arise from strong electron correlation in quantum materials such as cuprates and iron pnictides. Here, we report a direct observation of a smectic phase in a weakly correlated Dirac nodal line (DNL) semimetal GdSbxTe2-x. Incommensurate smectic charge modulation and intense local unidirectional nanostructure are visualized by using spectroscopic imaging - scanning tunneling microscopy. As topological materials with symmetry protected Dirac or Weyl fermions are mostly weakly correlated, the discovery of such an ELC phase are anomalous and raise questions on the origin of their emergence. Specifically, we demonstrate how chemical substitution generates these symmetry breaking phases before the system undergoes a charge density wave (CDW) - orthorhombic structural transition. Our results highlight the importance of impurities in realizing ELC phases and present a new material platform for exploring the interplay among quenched disorder, topology and electron correlation. Copyright © 2024, The Authors. All rights reserved.

关键词： Charge density waves

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Nonvolatile Tuning of Bragg Structures Using Transparent Phase-Change Materials

arXiv

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arXiv 2023年

作者： Nobile, Nicholas A. Lian, Chuanyu Sun, Hongyi Huang, Yi-Siou Mills, Brian Popescu, Cosmin Constantin Callahan, Dennis Hu, Juejun Ríos Ocampo, Carlos A. Youngblood, Nathan Electrical & Computer Engineering Department The University of Pittsburgh PittsburghPA15213 United States Department of Materials Science & Engineering University of Maryland College ParkMD20742 United States Institute for Research in Electronics & Applied Physics University of Maryland College ParkMD20742 United States Department for Materials Science & Engineering Massachusetts Institute of Technology CambridgeMA02139 United States Draper Scholar Program The Charles Stark Draper Laboratory Inc CambridgeMA02139 United States The Charles Stark Draper Laboratory Inc CambridgeMA02139 United States

Bragg gratings offer high-performance filtering and routing of light on-chip through a periodic modulation of a waveguide’s effective refractive index. Here, we model and experimentally demonstrate the use of Sb2Se3, a nonvolatile and transparent phase-change material, to tune the resonance conditions in two devices which leverage periodic Bragg gratings—a stopband filter and Fabry-Perot cavity. Through simulations, we show that similar refractive indices between silicon and amorphous Sb2Se3 can be used to induce broadband transparency, while the crystalline state can enhance the index contrast in these Bragg devices. Our experimental results show the promise and limitations of this design approach and highlight specific fabrication challenges which need to be addressed in future implementations. © 2023, CC BY.

关键词： Refractive index

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Model technology Service E-Participation - Voting (E-PV) for Political Communication between the Council of Regional Representatives (DPRD) and the Citizens Using the Framework Information technology Infrastructure Library (ITIL V.3) Transition Domain Service 7

Model Technology Service E-Participation - Voting (E-PV) for...

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7th International Conference on ICT for Smart Society, ICISS 2020

作者： Hilabi, Shofa Shofiah Harso Supangat, Suhono Hendric Spits Warnars, Harco Leslie Prabowo, Harjanto Mursitama, Tirta Nugraha Universitas Buana Perjuangan Faculty of Engineering and Computer Science Karawang Indonesia Institute of Technology Bandung School of Electrical Engineering and Informatics Bandung Indonesia Nusantara University Doctor of Computer Science Bina Computer Science Department BINUS Graduate Program Jakarta11530 Indonesia Bina Nusantara University Doctor of Computer Science Jakarta11530 Indonesia Bina Nusantara University Faculty of Humanities International Relations Department Jakarta11480 Indonesia

ISBN: (纸本)9781665404228

E-voting is an electronic voting information technology service, while E-participation is an information technology service for citizens of the public to provide reports, polls, or suggestions on government policies electronically. The technology Services E-Participation-VOT (EPV) model is a combined E-Participation and E-Voting service model. The concept of this service model is that citizens transform from E-participation and E-voting services into an EPV model. The purpose of this model is to provide information to participants (citizens) about online-based voting services. This method of developing the EP-Voting Anticipation (EPV) technology model uses agile methods that are effective and flexible in various cases of designing Information technology models for Information technology (IT) services that apply a Framework Information technology Infrastructure Library (ITIL). The results obtained from this study are an Information technology service system model that provides recommendations for participation in conducting electronic elections (E-Voting). © 2020 IEEE.

关键词： Surveys

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Comprehensive energy, economic, and environmental analysis of a hybrid photovoltaic–thermal (PVT) heat pump system

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Energy 2025年 331卷

作者： Hugo Arnesson Andreas V. Olympios Asmaa A. Harraz Jingyuan Xu Institute for Microstructure Technology Karlsruhe Institute of Technology Hermann-von-Helmholtz-Platz 1 76344 Eggenstein-Leopoldshafen Germany PV Technology Laboratory Department of Electrical and Computer Engineering University of Cyprus Nicosia Cyprus PHAETHON Centre of Excellence for Intelligent Efficient and Sustainable Energy Solutions Nicosia Cyprus Environmental Engineering Program University of Science and Technology Zewail City of Science and Technology Egypt

This study investigates a parallel indirect-expansion solar-assisted heat pump (SAHP) system integrating photovoltaic–thermal (PVT) collectors to meet domestic space heating, hot water, and appliance electricity demands for a typical household in Germany. A transient mathematical model captures the interdependencies between heat and electricity flows, enabling evaluation of thermodynamic, economic, and environmental performance across 54 heat pump designs with 3 refrigerants. The SAHP is compared to standalone heat pumps and natural gas boilers under varying electricity and natural gas prices. Results indicate that the SAHP system can cover over one-third of annual heating demand and half of appliance electricity demand using solar energy, with Munich achieving the highest solar coverage (39 %). HFC-32 (R32) outperforms propane, which in turn outperforms R410A, with levelized costs of energy, in electricity equivalents, of 0.272, 0.276 and 0.283 Euro/kWh, respectively. The SAHP system proves more cost-effective than standalone heat pumps or natural gas boilers unless energy prices are exceptionally low. Optimizing water tank designs for lower-temperature operation could further enhance SAHP competitiveness against PV-driven heat pumps.

关键词： Solar-assisted heat pump Energy–economic–environmental (3E) Photovoltaic–thermal (PVT) Propane refrigerant R32 refrigerant

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A Novel Wireless Sensor Network Data Aggregation Algorithm Based on Self-organizing Feature Mapping Neutral Network

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Ingenierie des Systemes d'Information 2019年第1期24卷 119-123页

作者： Zhou, Hong Yu, Kunming Program in Engineering Science Chung Hua University Hsinzhu30012 Taiwan Faculty of Computer and Software Engineering Huaiyin Institute of Technology Huai’an223005 China College of Computer Science and Electrical Engineer Chung Hua University Hsinzhu30012 Taiwan

Data aggregation is an efficient method to save energy and prolong the service life of wireless sensor networks (WSNs). In light of this, a data aggregation algorithm was constructed based on self-organizing feature mapping (SOFM) neural network and WSN cluster routing protocol. In this algorithm, each cluster was designed as a three-layer neural network model, which collect a large number of raw data. Then, the feature data were extracted from the raw data, and sent to the sink node. Through a simulation experiment, it is proved that the proposed algorithm, denoted as SOFMDA, outperformed a popular data aggregation method in energy consumption and data accuracy. © 2019 Lavoisier. All rights reserved.

关键词： Wireless sensor networks

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Stability, metallicity, and magnetism in niobium silicide nanofilms

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Physical Review Materials 2022年第6期6卷 064402-064402页

作者： Xuezeng Lu Dominic P. Goronzy Carlos G. Torres-Castanedo Paul Masih Das Maryam Kazemzadeh-Atoufi Anthony McFadden Corey Rae H. McRae Peter W. Voorhees Vinayak P. Dravid Michael J. Bedzyk Mark C. Hersam James M. Rondinelli Department of Materials Science and Engineering Northwestern University Evanston Illinois 60208 USA International Institute for Nanotechnology Northwestern University Evanston Illinois 60208 USA National Institute of Standards and Technology Boulder Colorado 80305 USA Department of Electrical Computer & Energy Engineering University of Colorado Boulder Boulder Colorado 80309 USA Department of Physics University of Colorado Boulder Colorado 80309 USA Northwestern University Atomic and Nanoscale Characterization Experimental Center (NUANCE) Northwestern University Evanston Illinois 60208 USA Department of Physics and Astronomy Northwestern University Evanston Illinois 60208 USA Applied Physics Program Northwestern University Evanston Illinois 60208 USA Department of Chemistry Northwestern University Evanston Illinois 60208 USA Department of Electrical and Computer Engineering Northwestern University Evanston Illinois 60208 USA

Modern superconducting qubits based on two-dimensional (2D) transmons typically involve the growth of Nb thin films on high-resistivity Si substrates. Since imperfections at the Nb-Si heterointerface have been implicated as a source of two-level systems that limit quantum coherence times, detailed characterization and understanding of niobium silicide interfacial layers are critical to improving superconducting qubit technology. While bulk binary intermetallic niobium silicide phases are well understood, the thermodynamic phase stability and properties of ultrathin niobium silicides, such as those found at the Nb-Si heterointerface in 2D transmons, have not yet been explored. Here, we report finite-sized effects for ultrathin niobium silicide films using density functional theory calculations and predict nanoscale stabilization of Nb6Si5 over the bulk α−Nb5Si3 phase. This result is consistent with our experimental observations of a niobium silicide interfacial layer between a sputtered Nb thin film and the underlying Si substrate. Furthermore, our calculations show that Nb6Si5 nanofilms are nonmagnetic, making them superior to nanofilms of α−Nb5Si3 that exhibit antiferromagnetic correlations detrimental to long coherence times in superconducting qubits. By providing atomic-scale insight into niobium silicide nanofilms, this paper can help guide ongoing efforts to optimize Nb-Si heterointerfaces for long coherence times in superconducting qubits.

关键词： Interface & surface thermodynamics Interfaces Superconducting qubits Thin films Density functional theory

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Winter Cabin Water Tap Monitor and Release System to Reduce Risk of Freezing 10

Winter Cabin Water Tap Monitor and Release System to Reduce ...

引用

10th IEEE Annual Ubiquitous Computing, Electronics and Mobile Communication Conference, UEMCON 2019

作者： Kaprielian, Paul L. Pham, Thach Young, Alex Dow, Douglas E. Grenquist, Scott A. Decker, Bruce M. Program in Electronic Eng. Technology Wentworth Institute of Technology Dept. of Electrical and Computer Engineering BostonMA United States

ISBN: (纸本)9781728138855

Frozen water pipes lead to leaks that result in property damage and repair costs. Frozen water pipes not only occur in northern climates, but also in more moderate climates that have occasional periods of temperatures below the freezing point. Water pipes at high risk for ice formation include ones outside of buildings, in poorly insulated structures or in seasonal buildings that are not heated during the winter months. Methods of protection include heating the building, insulation and heat tape on exposed water pipes, turning off the water supply and draining all pipes of water, or turning on a water valve to allow a continual flow of water through the pipes during the entire period having risk of low temperatures. The flow would hinder ice formation in the pipes. These protective measures have associated costs for equipment, heating fuel, and water loss. If the low temperature drops further or is sustained for longer periods than expected, there would still be a risk of frozen pipes. The purpose of this project was to develop and test a prototype system to monitor temperature, and initiate intermittent bursts of water flow only when temperatures are low enough to have risk of ice formation in the water pipes. The prototype utilized a temperature sensor, Arduino microcontroller, power supply, relay switch, and solenoid valve. The solenoid valve was incorporated into the water facet of a sink. When the sensor detected temperatures below the threshold of 25°C, intermittent bursts of flow were initiated, with 20 seconds of water flow followed by 2 minutes of no flow. Each flow event was recorded in a web service. A HTTP Get request was transmitted to a Google App Script program that stored the date and time in a Google Sheet. The owner or manager could remotely monitor the intermittent flow events. © 2019 IEEE.

关键词： Temperature

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Loss tangent fluctuations due to two-level systems in superconducting microwave resonators

arXiv

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arXiv 2024年

作者： Vallières, André Russell, Megan E. You, Xinyuan Garcia-Wetten, David A. Goronzy, Dominic P. Walker, Mitchell J. Bedzyk, Michael J. Hersam, Mark C. Romanenko, Alexander Lu, Yao Grassellino, Anna Koch, Jens McRae, Corey Rae H. Graduate Program in Applied Physics Northwestern University EvanstonIL60208 United States Fermi National Accelerator Laboratory BataviaIL60510 United States Department of Physics and Astronomy Northwestern University EvanstonIL60208 United States Department of Materials Science and Engineering Northwestern University EvanstonIL60208 United States Department of Chemistry Northwestern University EvanstonIL60208 United States Department of Electrical and Computer Engineering Northwestern University EvanstonIL60208 United States Center for Applied Physics and Superconducting Technologies Northwestern University EvanstonIL60208 United States Electrical Computing and Energy Engineering Department University of Colorado BoulderCO80309 United States Department of Physics University of Colorado BoulderCO80309 United States National Institute of Standards and Technology BoulderCO80305 United States

Superconducting microwave resonators are critical to quantum computing and sensing technologies. Additionally, they are common proxies for superconducting qubits when determining the effects of performance-limiting loss mechanisms such as from two-level systems (TLS). The extraction of these loss mechanisms is often performed by measuring the internal quality factor Qi as a function of power or temperature. In this work, we investigate large temporal fluctuations of Qi at low powers over periods of 12 to 16 hours (relative standard deviation σQi/Qi = 13%). These fluctuations are ubiquitous across multiple resonators, chips and cooldowns. We are able to attribute these fluctuations to variations in the TLS loss tangent due to two main indicators. First, measured fluctuations decrease as power and temperature increase. Second, for interleaved measurements, we observe correlations between low- and medium-power Qi fluctuations and an absence of correlations with high-power fluctuations. Agreement with the TLS loss tangent mean is obtained by performing measurements over a time span of a few hours. We hypothesize that, in addition to decoherence due to coupling to individual near-resonant TLS, superconducting qubits are affected by these observed TLS loss tangent fluctuations. © 2024, CC BY.

关键词： Qubits

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Performance limits due to thermal transport in graphene single-photon bolometers

arXiv

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arXiv 2023年

作者： Fried, Caleb Jordan Russell, B. Arnault, Ethan G. Huang, Bevin Lee, Gil-Ho Englund, Dirk Henriksen, Erik A. Fong, Kin Chung Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology CambridgeMA02139 United States Department of Earth and Planetary Sciences Harvard University CambridgeMA02138 United States Department of Physics Harvard University CambridgeMA02138 United States Raytheon BBN Quantum Engineering and Computing Group CambridgeMA02138 United States Department of Physics Washington University in St. Louis St. LouisMO United States Intelligence Community Postdoctoral Research Fellowship Program Massachusetts Institute of Technology CambridgeMA02139 United States Department of Physics Pohang University of Science and Technology Pohang790-784 Korea Republic of

In high-sensitivity bolometers and calorimeters, the photon absorption often occurs at a finite distance from the temperature sensor to accommodate antennas or avoid the degradation of superconducting circuitry exposed to radiation. As a result, thermal propagation from the input to the temperature readout can critically affect detector performance. In this report we model the performance of a graphene bolometer, accounting for electronic thermal diffusion and dissipation via electron-phonon coupling at low temperatures in three regimes: clean, supercollision, and resonant scattering. Our results affirm the feasibility of a superconducting readout without Cooper-pair breaking by mid- and near-infrared photons, and provide a recipe for designing graphene absorbers for calorimetric single-photon detectors. We investigate the tradeoff between the input-readout distance and detector efficiency, and predict an intrinsic timing jitter of ∼2.7 ps. Based on our result, we propose a spatial-mode-resolving photon detector to increase communication bandwidth. Copyright © 2023, The Authors. All rights reserved.

关键词： Graphene

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Lattice Transformation from 2-D to Quasi 1-D and Phonon Properties of Exfoliated ZrS2 and ZrSe2

arXiv

引用

arXiv 2022年

作者： Alsulami, Awsaf Alharbi, Majed Alsaffar, Fadhel Alolaiyan, Olaiyan Aljalham, Ghadeer Albawardi, Shahad Alsaggaf, Sarah Alamri, Faisal Tabbakh, Thamer A. Amer, Moh R. Center of Excellence for Green Nanotechnologies Joint Centers of Excellence Program King Abdulaziz City for Science and Technology Riyadh Saudi Arabia Department of Mechanical and Aerospace Engineering University of California Los Angeles Los AngelesCA90095 United States National Center for Nanotechnology Materials Science Institute King Abdulaziz City for Science and Technology Riyadh Saudi Arabia Department of Electrical and Computer Engineering University of California Los Angeles Los AngelesCA90095 United States

Recent reports on thermal and thermoelectric properties of emerging 2-Dimensional (2D) materials have shown promising results. Yet, most of these emerging materials are underrepresented or lack a consistent and thorough investigation. Among these materials are Zirconium based chalcogenides such as Zirconium Disulfide (ZrS2) and Zirconium Dieselenide (ZrSe2). Here, we investigate the thermal properties of these Zirconium based materials using confocal Raman spectroscopy. We observed 2 different and distinctive Raman signatures for exfoliated ZrX2 (where X = S or Se). These Raman modes generally depend on the shape of the exfoliated nanosheets, regardless of the incident laser polarization. These 2 shapes are divided into 2D- ZrX2 and quasi 1D- ZrX2. For 2D- ZrX2, Raman modes are in alignment with those reported in literature. However, for quasi 1D-ZrX2, we show that Raman modes are identical to exfoliated ZrX3 nanosheets, indicating a major lattice transformation from 2D to quasi-1D. We also measure thermal properties of each resonant Raman mode for each ZrX2 shape. Based on our measurements, most Raman modes exhibit a linear downshift dependence with temperature. However, for ZrS2, we see an upshift (blueshift) with temperature for A1g mode, which is attributed to non-harmonic effects caused by dipolar coupling with IR-active modes. Moreover, the observed temperature dependence coefficient for some phonon modes of quasi 1D-ZrX2 differ dramatically, which can be caused by the quasi 1D lattice. Finally, we measure phonon dynamics under optical heating for each of 2D-ZrX2 and quasi 1D-ZrX2 and show phonon confinement in quasi 1D-ZrX2 nanosheets. We extract the thermal conductivity and the interfacial thermal conductance for each of 2D-ZrX2 and quasi 1D-ZrX2 nanosheets. Our calculations indicate lower interfacial thermal conductance for quasi 1D-ZrX2 compared to 2D-ZrX2, which can be attributed to the phonon confinement in 1D. Based on our model, we show low thermal con

关键词： Thermal conductivity

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