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arXiv 2023年

作者： Jin, Zheting Ismail-Beigi, Sohrab Department of Applied Physics Yale University New HavenCT06520 United States Department of Physics Yale University New HavenCT06520 United States Department of Mechanical Engineering and Materials Science Yale University New HavenCT06520 United States

Materials-realistic microscopic theoretical descriptions of copper-based superconductors are challenging due to their complex crystal structures combined with strong electron interactions. Here, we demonstrate how density functional theory can accurately describe key structural, electronic, and magnetic properties of the normal state of the prototypical cuprate Bi2Sr2CaCu2O8+x (Bi-2212). We emphasize the importance of accounting for energy-lowering structural distortions, which then allows us to: (a) accurately describe the insulating antiferromagnetic (AFM) ground state of the undoped parent compound (in contrast to the metallic state predicted by previous ab initio studies);(b) identify numerous low-energy competing spin and charge stripe orders in the hole-overdoped material nearly degenerate in energy with the AFM ordered state, indicating strong spin fluctuations;(c) predict the lowest-energy hole-doped crystal structure including its long-range structural distortions and oxygen dopant positions that match high-resolution scanning transmission electron microscopy (STEM) measurements;and (d) describe electronic bands near the Fermi energy with flat antinodal dispersions and Fermi surfaces that in agreement with angle-resolved photoemission spectroscopy (ARPES) measurements and provide a clear explanation for the structural origins of the so-called "shadow bands". We also show how one must go beyond band theory and include fully dynamic spin fluctuations via a many-body approach when aiming to make quantitative predictions to measure the ARPES spectra in the overdoped material. Finally, regarding spatial inhomogeneity, we show that the local structure at the CuO2 layer, rather than dopant electrostatic effects, modulates the local charge-transfer gaps, local correlation strengths, and by extension the local superconducting gaps. © 2023, CC BY.

关键词： Spin fluctuations

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Enhancing Fieldwork Productivity in Subsurface Characterization: Advancements in Data Acquisition with Masw-Ds

SSRN

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SSRN 2024年

作者： Hamdan, Hamdan Ali Kritikakis, George Elsamani, Mahmoud Harb, Mahmoud Abdel-Fattah, Mohamed Soupios, Pantelis University of Sharjah Petroleum Geosciences and Remote Sensing Program Department of Applied Physics and Astronomy United Arab Emirates Applied Geophysics Lab Technical University of Crete Greece United Arab Emirates Department of Geosciences College of Petroleum Engineering and Geosciences King Fahd University of Petroleum and Minerals Dhahran31261 Saudi Arabia

The Multichannel Analysis of Surface Waves (MASW) method utilizes low-frequency surface waves, to characterize the shallow subsurface layers. It is a very useful tool in geotechnical engineering for evaluating soil quality and mapping the characteristics of the upper sedimentary layers. Despite its efficiency, the limited productivity of conventional MASW due to its relatively slow data acquisition process presents a challenge, especially for large-scale projects, such as those carried out in the Gulf Cooperation Council (GCC) region. To address this issue, we introduce the Multichannel Analysis of Surface Waves-Dual Streamer (MASW-DS) technique to enhance fieldwork productivity by almost 90%. This approach involves towing two parallel land streamers simultaneously behind a truck and enabling the acquisition of data from the two adjacent MASW profiles with a single source activated between the two land streamers. Our study evaluates the precision and effectiveness of MASW-DS through a set of synthetic and real data testing across diverse sites, demonstrating its potential for expedited surveys and reduced project costs. While MASW-DS introduces assumptions that may impact the resulting S-wave profiles, our findings indicate its comparable performance to conventional MASW, with negligible differences in dispersion curves and promising results, even in challenging geological settings. The proposed technique managed to reproduce the S-wave profiles resulting from the classic MASW deployment in the framework of an acceptable error for engineers. These results prove the reliability of the MASW-DS technique for subsurface characterization while achieving significant time and cost savings. MASW-DS also holds the potential for further enhancement by towing more than two land streamers simultaneously, positioning it as a valuable and effective tool for geotechnical investigations and civil engineering projects worldwide. © 2024, The Authors. All rights reserved.

关键词： Geotechnical engineering

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Ultrafast switchable polar and magnetic orders by nonlinear light-matter interaction

arXiv

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arXiv 2025年

作者： Wei, Haoyu Kaplan, Daniel Xu, Haowei Li, Ju Department of Materials Science and Engineering Massachusetts Institute of Technology CambridgeMA02139 United States Tsien Excellence in Engineering Program Tsinghua University Beijing100084 China Department of Applied Physics Yale University New HavenCT06520 United States Center for Materials Theory Department of Physics and Astronomy Rutgers University PiscatawayNJ08854 United States Department of Nuclear Science and Engineering Massachusetts Institute of Technology CambridgeMA02139 United States

An outstanding challenge in materials science and physics is the harnessing of light for switching charge order in e.g., ferroelectrics. Here we propose a mechanism through which electrons in ferroelectric bilayers excited with light cause ionic structural transitions. Using perturbation theory within a many-body formalism, we show that the ionic coupling is mediated by a resonant change in electronic occupation functions, ultimately governed by the quantum geometric tensor (QGT) of the ground state. Furthermore, we show that such transitions are generally accompanied by multiferroic order switching. We demonstrate two examples of light-induced structural and polarization switching under this mechanism using first-principle calculations on bilayer CrI3 and MoTe2 . We show that the two materials can switch between atomic stackings with a light intensity threshold of only 101-102GW/cm2, a value 1-3 orders of magnitude lower than that required by direct light-ion coupling thanks to the superior efficiency of resonant light-electron coupling. Since such switching is fast, highly controllable, contactless, and reversible, it is promising for use in optically controlled nonvolatile memory, nanophotonics and electronic devices. Copyright © 2025, The Authors. All rights reserved.

关键词： Perturbation techniques

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Effects of Artificial Collisions, Filtering, and Nonlocal Closure Approaches on Hermite-based Vlasov-Poisson Simulations

arXiv

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arXiv 2024年

作者： Issan, Opal Chapurin, Oleksandr Koshkarov, Oleksandr Delzanno, Gian Luca Department of Mechanical and Aerospace Engineering University of California San Diego La Jolla CA United States T-5 Applied Mathematics and Plasma Physics Group Los Alamos National Laboratory Los AlamosNM United States

Kinetic simulations of collisionless plasmas are computationally challenging due to phase space mixing and filamentation, resulting in fine-scale velocity structures. This study compares three methods developed to reduce artifacts related to limited velocity resolution in Hermite-based Vlasov-Poisson simulations: artificial collisions, filtering, and nonlocal closure approaches. We evaluate each method’s performance in approximating the linear kinetic response function and suppressing recurrence in linear and nonlinear regimes. Numerical simulations of Landau damping demonstrate that artificial collisions, particularly higher orders of the Lenard-Bernstein collisional operator, most effectively recover the correct damping rate across a range of wavenumbers. Moreover, Hou-Li filtering and nonlocal closures underdamp high wavenumber modes in linear simulations, and the Lenard-Bernstein collisional operator overdamps low wavenumber modes in both linear and nonlinear simulations. This study demonstrates that hypercollisions offer a robust approach to kinetic simulations, accurately capturing collisionless dynamics with limited velocity resolution. © 2024, CC BY.

关键词： Damping

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An Efficient Three-Factor Authenticated Key Agreement Technique Using FCM Under HC-IoT Architectures

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Computers, Materials & Continua 2022年第7期72卷 1373-1389页

作者： Chandrashekhar Meshram Agbotiname Lucky Imoize Sajjad Shaukat Jamal Parkash Tambare Adel R.Alharbi Iqtadar Hussain Department of Post Graduate Studies and Research in Mathematics Jayawanti Haksar Government Post-Graduation CollegeCollege of Chhindwara UniversityBetul460001M.P.India Department of Electrical and Electronics Engineering Faculty of EngineeringUniversity of LagosAkokaLagos100213Nigeria Department of Electrical Engineering and Information Technology Institute of Digital CommunicationRuhr University44801BochumGermany Department of Mathematics College of ScienceKing Khalid UniversityAbhaSaudi Arabia Water Resources&Applied Mathematics Research Lab Nagpur440027India College of Computing and Information Technology University of TabukTabuk71491Saudi Arabia Mathematics Program Department of MathematicsStatistics and PhysicsCollege of Arts and SciencesQatar University2713DohaQatar

The Human-Centered Internet of Things(HC-IoT)is fast becoming a hotbed of security and privacy *** users can establish a common session key through a trusted server over an open communication channel using a three-party authenticated key *** of the early authenticated key agreement systems relied on pairing,hashing,or modular exponentiation processes that are computationally intensive and *** order to address this problem,this paper offers a new three-party authenticated key agreement technique based on fractional chaotic *** new scheme uses fractional chaotic maps and supports the dynamic sensing of HC-IoT devices in the network architecture without a password *** projected security scheme utilized a hash function,which works well for the resource-limited HC-IoT *** results show that our new technique is resistant to password guessing attacks since it does not use a ***,our approach provides users with comprehensive privacy protection,ensuring that a user forgery attack causes no ***,our new technique offers better security features than the techniques currently available in the literature.

关键词： Three-party authenticated key agreement anonymity fractional chaotic maps Chebyshev polynomial password table human-centered internet of things(HC-IoT)

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Orientational ordering in active nematic solids

arXiv

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arXiv 2025年

作者： Yang, Haiqian Guo, Ming Mahadevan, L. Department of Mechanical Engineering Massachusetts Institute of Technology CambridgeMA02139 United States School of Engineering and Applied Sciences Harvard University CambridgeMA02138 United States Department of Organismic and Evolutionary Biology Harvard University CambridgeMA02138 United States Department of Physics Harvard University CambridgeMA02138 United States

In vivo and in vitro systems of cells and extra-cellular matrix (ECM) systems are well known to form ordered patterns of orientationally aligned fibers. Here, we interpret them as active analogs of the (disordered) isotropic to the (ordered) nematic phase transition seen in passive liquid crystalline elastomers. A minimal theoretical framework that couples cellular activity (embodied as mechanical stress) and the finite deformation elasticity of liquid crystal elastomers sets the stage to explain these patterns. Linear stability analysis of the governing equations about simple homogeneous isotropic base states shows how the onset of periodic morphologies depends on the activity, elasticity, and applied strain, provides an expression for the wavelength of the instability, and is qualitatively consistent with observations of cell-ECM experiments. Finite element simulations of the nonlinear problem corroborate the results of linear analysis. These results provide quantitative insights into the onset and evolution of nematic order in cell-matrix composites. © 2025, CC BY-NC-ND.

关键词： Linear stability analysis

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Deep-Strong Coupling between Cavity Photons and Terahertz TO Phonons in PbTe

Deep-Strong Coupling between Cavity Photons and Terahertz TO...

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2023 Conference on Lasers and Electro-Optics, CLEO 2023

作者： Baydin, Andrey Manjappa, Manukumara Mishra, Sobhan Subhra Xu, Hongjing Tay, Fuyang Kim, Dasom Hernandez, Felix G.G. Rappl, Paulo H.O. Abramof, Eduardo Singh, Ranjan Kono, Junichiro Department of Electrical and Computer Engineering Rice University HoustonTX77005 United States Smalley-Curl Institute Rice University HoustonTX77005 United States Instrumentation and Applied Physics Department Indian Institute of Science Bangalore560012 India Center for Disruptive Photonic Technologies The Photonics Institute Nanyang Technological University 639798 Singapore Department of Physics and Astronomy Rice University HoustonTX77005 United States Applied Physics Graduate Program Smalley-Curl Institute Rice University HoustonTX77005 United States Instituto de Física Universidade de Sao Paulo SP Sao Paulo05508-090 Brazil Laboratorio Associado de Sensores e Materiais Instituto Nacional de Pesquisas Espaciais SP Sao Jose dos Campos12201-970 Brazil Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University 637371 Singapore Department of Material Science and NanoEngineering Rice University HoustonTX77005 United States

We have investigated the resonant coupling of photons with TO phonons in lead telluride in small-mode-volume terahertz cavities, observing a giant vacuum Rabi splitting on the order of the bare cavity-phonon frequency... 详细信息

ISBN: (纸本)9781957171258

关键词： Photons

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Modeling multi-legged robot locomotion with slipping and its experimental validation

arXiv

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arXiv 2023年

作者： Wu, Ziyou Zhao, Dan Revzen, Shai Robotics University of Michigan United States Mechanical Engineering University of Michigan United States Electrical Engineering and Computer Science University of Michigan United States Ecology and Evolutionary Biology University of Michigan United States Applied Physics Program University of Michigan United States

Multi-legged robots with six or more legs are not in common use, despite designs with superior stability, maneuverability, and a low number of actuators being available for over 20 years. This may be in part due to the difficulty in modeling multi-legged motion with slipping and producing reliable predictions of body velocity. Here we present a detailed measurement of the foot contact forces in a hexapedal robot with multiple sliding contacts, and provide an algorithm for predicting these contact forces and the body velocity. The algorithm relies on the recently published observation that even while slipping, multi-legged robots are principally kinematic, and employ a friction law ansatz that allows us to compute the shape-change to body-velocity connection and the foot contact forces. This results in the ability to simulate motion plans for a large number of contacts, each potentially with slipping. Furthermore, in homogeneous environments, this kind of simulation can run in (parallel) logarithmic time of the planning horizon. © 2023, CC BY.

关键词： Friction

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Impact of Ordering of Heterogeneous Vehicles on String Stability

Impact of Ordering of Heterogeneous Vehicles on String Stabi...

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International Conference on Intelligent Transportation

作者： Neelkamal Somisetty Harsha Nagarajan Swaroop Darbha Department of Mechanical Engineering Texas A & M University College Station TX USA Applied Mathematics and Plasma Physics (T-5) Los Alamos National Laboratory Los Alamos NM USA

Amplification of errors can occur in a string of vehicles equipped with an Adaptive Cruise Control System (ACC) and Cooperative Adaptive Cruise Control System (CACC), which can lead to string instability and rear-end collisions in a platoon. Traditionally, homogeneous vehicle strings have been considered in the literature, wherein every vehicle adopts the same time headway setting. A lower bound on the employable time headway in terms of maximum parasitic lag ensures string stability. Typically, vehicles with ACC and CACC systems are provided with a set of finite and discrete time headway settings choices; this leads to heterogeneity in traffic. In this paper, we address the impact of heterogeneity in time headway among autonomous and connected vehicles on string stability. We provide an analysis of the ordering of vehicles with different time headways and its effects on the spacing error between the lead and last vehicles of the platoon. We pose the problem of minimal spacing error between the lead and last vehicles as a Mixed-Integer Semi-Definite program (MISDP). Since solving an MISDP is intractable, we propose an exhaustive and a heuristic ordering-enumeration algorithm. In these algorithms, a series of continuous Semi-Definite programs (SDPs) are solved to determine the “best” and “worst” ordering of vehicles with respect to the minimum spacing error for smaller-scale platoons. We present numerical results for different platoon sizes to corroborate the analysis of the effects of vehicles employing different time headways on string stability.

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Internal dose assessment of lymphoma 18F-FDG Positron Emission Tomography (PET) scan

Internal dose assessment of lymphoma 18F-FDG Positron Emissi...

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2023 National physics Seminar, SNF 2023

作者： Murat, H. Karim, M.K.A. Kechik, M.M.A. Amer, M.F. Razak, H.R.A. Kamal, I. Chew, M.T. Department of Physics Faculty of Science Universiti Putra Malaysia Selangor Serdang Malaysia Department of Nuclear Medicine Hospital Sultanah Aminah Johor Bahru Johor Malaysia Medical Imaging Program College of Medicine and Health St Luke's Campus University of Exeter DevonEX1 2LU United Kingdom Medical Imaging Department KPJ Healthcare University Nilai Negeri Sembilan Malaysia Research Centre for Applied Physics and Radiation Technologies School of Engineering and Technology Sunway University Petaling Jaya Malaysia

This study aimed to assess the internal radiation exposure of patients who have undergone a Positron Emission Tomography (PET) scan using 18F-FDG radiopharmaceutical. A total of 24 patients (8 men, 16 women, with an average age of 43.88 ± 18.57 years and weight of 57.54 ± 13.04 kg) who had been diagnosed with lymphoma were administered with 300.80 ± 23.09 MBq of 18F-FDG for a PET scan of the whole body. The IDAC-Dose 2.1 program, developed by the International Commission on Radiological Protection (ICRP), was used to measure absorbed and effective doses. The organs selected for absorbed dose analysis were the breast, kidneys, adrenals, liver, and brain, with the brain receiving the highest absorbed dose and the breast receiving the lowest absorbed dose. The effective dose for all patients was 4.85 ± 0.37 mSv, and the ratio of the effective dose to the administered activity was 1.611 × 10-2 mSv/MBq. The safety of the current practice using 18F-FDG PET scan was ascertained, given that the ratio of effective dose to administered activity was lower than 1.9 x 10-2 mSv/MBq. © Published under licence by IOP Publishing Ltd.

关键词： Positron emission tomography

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