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Unraveling exciton dynamics in an atomically thin van der Waals magnet

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Unraveling exciton dynamics in an atomically thin van der Wa...

International Conference on Infrared and Millimeter Waves

作者： Niloufar Nilforoushan Christian Meineke Jakob Schlosser Martin Zizlsperger Marlene Liebich Kseniia Mosina Sophia Terres Alexey Chernikov Zdenek Sofer Markus A. Huber Matthias Florian Mackillo Kira Florian Dirnberger Rupert Huber Department of Physics and Regensburg Center for Ultrafast Nanoscopy (RUN) University of Regensburg Regensburg Germany Department of Inorganic Chemistry University of Chemistry and Technology Prague Prague 6 Czech Republic Institute of Applied Physics and Würzburg-Dresden Cluster of Excellence Dresden University of Technology Dresden Germany Dept. of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA

ISBN: (数字)9798350370324

ISBN: (纸本)9798350370331

Within the realm of atomically thin semiconductors, CrSBr stands out uniquely as it harbors quasi-one-dimensional magnetic excitons in both its bulk and monolayer forms. Despite its fundamental significance, the precise exciton formation, relaxation and decay dynamics remained elusive. While terahertz polarization probing offers a direct avenue for tracking excitons, the resulting far-field signal can be affected by signals originating beyond the lateral dimensions of the sample. Here, we combine terahertz polarization spectroscopy with near-field microscopy to unveil the sub-picosecond decay dynamics of paramagnetic excitons in a CrSBr monolayer, which is faster by a factor of 30 than its bulk counterpart. Our analysis also unravels low-energy fingerprints of bound and unbound electron-hole pairs in bulk and gives access to the non-equilibrium dielectric function of the monolayer. These findings provide direct insight into the ultrafast dielectric response of quasi-one-dimensional excitons in CrSBr, with potential applications in quantum devices leveraging ultrathin van der Waals magnets.

关键词： Spectroscopy Millimeter wave devices Excitons Atomic layer deposition Fingerprint recognition Dielectrics Electron microscopy Magnets Magnetic semiconductors Magnetic force microscopy

Active Disturbance Rejection Control for 3D Crane Systems

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Procedia computer science 2024年 242卷 976-983页

作者： Raul-Cristian Roman Radu-Emil Precup Emil M. Petriu Politehnica University of Timisoara Dept. Automation and Applied Informatics Bd. V. Parvan 2 300223 Timişoara Romania Center for Fundamental and Advanced Tech. Res. Romanian Academy – Timisoara Br. Bd. Mihai Viteazu 24 300223 Timisoara Romania University of Ottawa School of Electrical Engineering and Computer Science 800 King Eduard Ottawa ON K1N 6N5 Canada

Active Disturbance Rejection Control (ADRC) is a data-driven algorithm that offers a promising approach for robust control design. This paper investigates the effectiveness of first-order and second-order ADRC for 3D cranes. To compare the results fairly and reduce the heuristics in parameter tuning, the ADRC parameters were optimally computed via the African Vultures Optimization Algorithm. Both controllers based on ADRC are validated using experiments on a 3D crane laboratory system and their design and performance evaluation are done by minimizing the sum of squared errors. The results demonstrate the robustness of the ADRCs. This comparative analysis highlights the advantages and limitations of both control strategies, providing valuable insights for selecting the appropriate ADRC order for specific applications.

关键词： 3D crane systems ADRC data-driven control optimization

Hierarchical Federated Learning based Anomaly Detection using digital twins for smart healthcare

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arXiv 2021年

作者： Gupta, Deepti Kayode, Olumide Bhatt, Smriti Gupta, Maanak Tosun, Ali Saman Dept. of Computer Science University of Texas at San Antonio San AntonioTX78249 United States Dept. of Computer Science Frostburg State University FrostburgMD21532 United States Dept. of Computer and Information Technology Purdue University West LafayetteIN47907 United States Dept. of Computer Science Tennessee Technological University CookevilleTN38505 United States Dept. of Math. and Comp. Sci. University of North Carolina at Pembroke PembrokeNC28372 United States

Internet of Medical Things (IoMT) is becoming ubiquitous with a proliferation of smart medical devices and applications used in smart hospitals, smart-home based care, and nursing homes. It utilizes smart medical devices and cloud computing services along with core Internet of Things (IoT) technologies to sense patients' vital body parameters, monitor health conditions and generate multivariate data to support just-in-time health services. Mostly, this large amount of data is analyzed in centralized servers. Anomaly Detection (AD) in a centralized healthcare ecosystem is often plagued by significant delays in response time with high performance overhead. Moreover, there are inherent privacy issues associated with sending patients' personal health data to a centralized server, which may also introduce several security threats to the AD model, such as possibility of data poisoning. To overcome these issues with centralized AD models, here we propose a Federated Learning (FL) based AD model which utilizes edge cloudlets to run AD models locally without sharing patients' data. Since existing FL approaches perform aggregation on a single server which restricts the scope of FL, in this paper, we introduce a hierarchical FL that allows aggregation at different levels enabling multiparty collaboration. We introduce a novel disease-based grouping mechanism where different AD models are grouped based on specific types of diseases. Furthermore, we develop a new Federated Time Distributed (FEDTIMEDIS) Long Short-Term Memory (LSTM) approach to train the AD model. We present a Remote Patient Monitoring (RPM) use case to demonstrate our model, and illustrate a proof-of-concept implementation using Digital Twin (DT) and edge cloudlets. © 2021, CC BY.

关键词： Internet of things

Two variable polynomial congruences and capacity theory

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arXiv 2021年

作者： Chinburg, Ted Hemenway Falk, B. Heninger, N. Scherr, Z. Dept. of Mathematics Univ. of Pennsylvania PhiladelphiaPA19104 United States Dept. of Computer Science Univ. of Pennsylvania PhiladelphiaPA19104 United States Dept. of Computer Science and Engineering U. C. S. D. La Jolla CA92093 United States Dept. of Math and Computer Science Susquehanna University SelinsgrovePA17870 United States

We use capacity theory to analyze Coppersmith's method for finding small solutions of linear two variable polynomial congruences. We show that the method will succeed in a positive proportion of cases and fail in a different positive proportion of cases. We also bound the number of small solutions via capacity *** Codes 14H25, 11H06 Copyright © 2021, The Authors. All rights reserved.

关键词： Polynomials

GWO-based Modeling of an Unstable Transport System 9th

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GWO-based Modeling of an Unstable Transport System

9th International Conference on Information Technology and Quantitative Management, ITQM 2022

作者： Gale-Cazan, Cristiana-Bogdana Bojan-Dragos, Claudia-Adina Precup, Radu-Emil Roman, Raul-Cristian Petriu, Emil M Szedlak-Stinean, Alexandra-Iulia Politehnica University of Timisoara Dept. Automation and Applied Informatics Bd. V. Parvan 2 Timisoara300223 Romania Center for Fundamental and Advanced Technical Research Romanian Academy Timisoara Branch Bd. Mihai Viteazu 24 Timisoara300223 Romania University of Ottawa School of Electrical Engineering and Computer Science 800 King Eduard OttawaONK1N 6N5 Canada

The goal of this paper is to obtain optimal models of an unstable transport system, which is a nonlinear process represented by the two-wheeled unstable transport system. An optimization problem is defined in order to ideally minimize and practically reduce the differences of the outputs of the real-time laboratory equipment with respect to the outputs of the nonlinear model. The parameters of the nonlinear models are optimally tuned using a recent metaheuristic optimization algorithm, namely the Grey Wolf Optimizer, which solves three optimization problems. A comparison of the responses of the real-time laboratory equipment and the derived optimal nonlinear models is carried out in various simulation scenarios, which are discussed and analyzed. © 2022 The Authors. Published by Elsevier B.V.

关键词： Optimization

Thermal imaging in the 3-5 micron range for precise localization of defects: Application on frescoes at the Sforza Castle 8

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Thermal imaging in the 3-5 micron range for precise localiza...

Optics for Arts, Architecture, and Archaeology VIII 2021

作者： Daffara, Claudia Parisotto, Simone Mazzocato, Sara Mariotti, Paola Ilaria Ambrosini, Dario Dept. of Computer Science University of Verona st. le Grazie 15 VeronaI-37134 Italy Dept. of Applied Mathematics and Theoretical Physics University of Cambridge Wilberforce Road CambridgeCB3 0WA United Kingdom FirenzeI-50129 Italy University of L'Aquila pl. Pontieri 1 L'AquilaI-67100 Italy

ISBN: (数字)9781510644038

ISBN: (纸本)9781510644021

Infrared methods are of great importance in nondestructive testing of artworks, allowing a remote and wide-field imaging of interesting hidden features. Here we discuss a workflow based on thermal imaging in the mid infrared 3-5 micron range for the evaluation of subsurface defects in frescoes. Particular attention is payed to obtaining a high resolution (submillimetric) localization of the defects. The transfer of diagnostics techniques into real world applications, is discussed through the proof of concept of the proposed workflow on frescoes at the Sforza Castle (Milan, Italy). © 2021 SPIE · CCC code: 0277-786X/21/$21 ·

关键词： Defects

Kemeny consensus complexity

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arXiv 2021年

作者： Fitzsimmons, Zack Hemaspaandra, Edith Dept. of Math. and Computer Science College of the Holy Cross WorcesterMA01610 United States Department of Computer Science Rochester Institute of Technology RochesterNY14623 United States

The computational study of election problems generally focuses on questions related to the winner or set of winners of an election. But social preference functions such as Kemeny rule output a full ranking of the candidates (a consensus). We study the complexity of consensus-related questions, with a particular focus on Kemeny and its qualitative version Slater. The simplest of these questions is the problem of determining whether a ranking is a consensus, and we show that this problem is coNP-complete. We also study the natural question of the complexity of manipulative actions that have a specific consensus as a goal. Though determining whether a ranking is a Kemeny consensus is hard, the optimal action for manipulators is to simply vote their desired consensus. We provide evidence that this simplicity is caused by the combination of election system (Kemeny), manipulative action (manipulation), and manipulative goal (consensus). In the process we provide the first completeness results at the second level of the polynomial hierarchy for electoral manipulation and for optimal solution recognition. Copyright © 2021, The Authors. All rights reserved.

关键词： Polynomials

Analysis of queue length prediction from probe vehicles problem with bunch arrival headways

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arXiv 2020年

作者： Comert, Gurcan Jones, Stacey Franklin Dept. of Math and Computer Science Benedict College Dept. of Math and Computer Science Office of Institutional Effectiveness Sponsored Programs Benedict College

This paper discusses the real-time prediction of queue lengths from probe vehicles for the Bunch arrival headways at an isolated intersection for undersaturated conditions. The paper incorporates the bunching effect of the traffic into the evaluation of the accuracy of the predictions as a function of proportion of probe vehicles to entire vehicle population. Formulations are presented for predicting the expected queue length and its variance based on Negative Exponential and Bunched Exponential vehicle headways. Numerical results for both vehicle headway types are documented to show how prediction errors behave by the volume to capacity ratio and probe proportions. It is found that the Poisson arrivals generate conservative confidence intervals and demand higher probe proportions compared to Bunched Exponential headways at the same arrival rate and probe proportion. Copyright © 2020, The Authors. All rights reserved.

关键词： Queueing theory

AMG Preconditioners based on Parallel Hybrid Coarsening and Multi-objective Graph Matching

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AMG Preconditioners based on Parallel Hybrid Coarsening and ...

Euromicro Conference on Parallel, Distributed and Network-Based Processing

作者： Pasqua D'Ambra Fabio Durastante S M Ferdous Salvatore Filippone Mahantesh Halappanavar Alex Pothen National Research Council (CNR) Institute for Applied Computing “M. Picone” (IAC) Napoli Italy Department of Mathematics University of Pisa Pisa Italy Pacific Northwest National Laboratory Physical and Computational Sciences Richland WA USA Dept. of Civil and Computer Engineering University of Rome Tor-Vergata Rome Italy Computer Science Department Purdue University West Lafayette IN USA

We describe preliminary results from a multi-objective graph matching algorithm, in the coarsening step of an aggregation-based Algebraic MultiGrid (AMG) preconditioner, for solving large and sparse linear systems of equations on high-end parallel computers. We have two objectives. First, we wish to improve the convergence behavior of the AMG method when applied to highly anisotropic problems. Second, we wish to extend the parallel package PSCToolkit to exploit multi-threaded parallelism at the node level on multi-core processors. Our matching proposal balances the need to simultaneously compute high weights and large cardinalities by a new formulation of the weighted matching problem combining both these objectives using a parameter $\lambda$ . We compute the matching by a parallel $2/3-\varepsilon$ -approximation algorithm for maximum weight matchings. Results with the new matching algorithm show that for a suitable choice of the parameter $\lambda$ we compute effective preconditioners in the presence of anisotropy, i.e., smaller solve times, setup times, iterations counts, and operator complexity.

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