检索结果-内蒙古大学图书馆

arXiv 2018年

作者： Watanabe, Yohei Hino, Ken-Ichi Maeshima, Nobuya Petek, Hrvoje Hase, Muneaki Doctoral Program in Materials Science Graduate School of Pure and Applied Sciences University of Tsukuba Tsukuba Ibaraki305-8573 Japan Division of Materials Science Faculty of Pure and Applied Sciences University of Tsukuba Tsukuba305-8573 Japan Center for Computational Sciences University of Tsukuba Tsukuba305-8577 Japan Department of Physics and Astronomy Pittsburgh Quantum Institute University of Pittsburgh PittsburghPA15260 United States Division of Applied Physics Faculty of Pure and Applied Sciences University of Tsukuba Tsukuba305-8573 Japan

We investigate the spectral profiles of time signals attributed to coherent phonon generation in an undoped Si crystal. Here, the retarded longitudinal-optical (LO) phonon Green function relevant to the temporal variance of induced charge density of ionic cores is calculated by employing the polaronic quasiparticle model developed by the authors [Y. Watanabe et al., Phys. Rev. B 95, 014301 (2017);ibid., 96, 125204 (2017)]. The spectral asymmetry is revealed in the frequency domain of the signals under the condition that an LO phonon mode stays almost energetically resonant with a plasmon mode in the early time region;this lasts for approximately 100 fs immediately after the irradiation of an ultrashort pump-laser pulse. It is understood that based on the adiabatic picture in time, this asymmetry is caused by the Rosen-Zener coupling between both modes. The associated experimental results are obtained by measuring time-dependent electro-optic reflectivity signals, and it is proved that these are in harmony with the calculated ones. The spectra become more symmetric, as the photoexcited carrier density further changes from that meeting the above condition to higher and lower sides of carrier densities. Moreover, the effect of optical nutation of carrier density on the CP signals is addressed, and the present results are compared with the asymmetry caused by transient Fano resonance, and the spectral profiles observed in a GaAs crystal in the text. Copyright © 2018, The Authors. All rights reserved.

关键词： Carrier concentration

来源：评论

学校读者我要写书评

暂无评论

TOI-2015 b: A sub-Neptune in strong gravitational interaction with an outer non-transiting planet

引用

Astronomy and Astrophysics 2025年 695卷

作者： Barkaoui, K. Korth, J. Gaidos, E. Agol, E. Parviainen, H. Pozuelos, F.J. Palle, E. Narita, N. Grimm, S. Brady, M. Bean, J.L. Morello, G. Rackham, B.V. Burgasser, A.J. Van Grootel, V. Rojas-Ayala, B. Seifahrt, A. Marfil, E. Passegger, V.M. Stalport, M. Gillon, M. Collins, K.A. Shporer, A. Giacalone, S. Yalçinkaya, S. Ducrot, E. Timmermans, M. Triaud, A.H.M.J. De Wit, J. Soubkiou, A. Watkins, C.N. Aganze, C. Alonso, R. Amado, P.J. Basant, R. Baştürk, Ö. Benkhaldoun, Z. Burdanov, A. Calatayud-Borras, Y. Chouqar, J. Conti, D.M. Collins, K.I. Davoudi, F. Delrez, L. Dressing, C.D. De Leon, J. Dévora-Pajares, M. Demory, B.O. Dransfield, G. Esparza-Borges, E. Fernández-Rodriguez, G. Fukuda, I. Fukui, A. Gallardo, P.P.M. Garcia, L. Garcia, N.A. Ghachoui, M. Geraldía-González, S. Gómez Maqueo Chew, Y. González-Rodríguez, J. Günther, M.N. Hayashi, Y. Horne, K. Hooton, M.J. Hsu, C.C. Ikuta, K. Isogai, K. Jehin, E. Jenkins, J.M. Kawauchi, K. Kagetani, T. Kawai, Y. Kasper, D. Kielkopf, J.F. Klagyivik, P. Lacedelli, G. Latham, D.W. Libotte, F. Luque, R. Livingston, J.H. Mancini, L. Massey, B. Mori, M. Muñoz Torres, S. Murgas, F. Niraula, P. Orell-Miquel, J. Rapetti, David Rebolo-López, R. Ricker, G. Papini, R. Pedersen, P.P. Peláez-Torres, A. Pérez-Prieto, J.A. Poultourtzidis, E. Rodriguez, P.M. Queloz, D. Savel, A.B. Schanche, N. Sánchez-Benavente, M. Sibbald, L. Sefako, R. Sohy, S. Sota, A. Schwarz, R.P. Seager, S. Sebastian, D. Southworth, J. Stangret, M. Stefánsson, G. Stürmer, J. Srdoc, G. Thompson, S.J. Terada, Y. Vanderspek, R. Wang, G. Watanabe, N. Wilkin, F.P. Winn, J. Wells, R.D. Ziegler, C. Zúñiga-Fernández, S. Astrobiology Research Unit Université de Liège Allée du 6 Août 19C Liège4000 Belgium Department of Earth Atmospheric and Planetary Science Massachusetts Institute of Technology 77 Massachusetts Avenue CambridgeMA02139 United States Calle Vía Láctea s/n Tenerife La Laguna38200 Spain Lund Observatory Division of Astrophysics Department of Physics Lund University Box 118 Lund22100 Sweden Department of Earth Sciences University of Hawaii at Manoa 1680 East-West Rd HonoluluHI96822 United States Institute for Astrophysics University of Vienna Türkenschanzstrasse 17 Vienna1180 Austria Department of Astronomy and Astrobiology Program University of Washington Box 351580 SeattleWA98195 United States NExSS Virtual Planetary Laboratory University of Washington Box 351580 SeattleWA98195 United States Tenerife La LagunaE-38206 Spain Glorieta de la Astronomía s/n Granada18008 Spain INAF-Palermo Astronomical Observatory Piazza del Parlamento 1 Palermo90134 Italy Komaba Institute for Science University of Tokyo 3-8-1 Komaba Tokyo Meguro153-8902 Japan Astrobiology Center 2-21-1 Osawa Tokyo Mitaka181-8588 Japan Research Institute for Advanced Computer Science Universities Space Research Association WashingtonDC20024 United States Institute for Particle Physics and Astrophysics ETH Zürich OttoStern-Weg 5 Zürich8093 Switzerland Department of Astrophysics University of Zürich Winterthurerstrasse 190 Zürich8057 Switzerland Department of Astronomy & Astrophysics University of Chicago ChicagoIL United States Department of Physics Kavli Institute for Astrophysics and Space Research Massachusetts Institute of Technology CambridgeMA02139 United States Institute Université de Liège Allée du 6 Août 19C LiègeB-4000 Belgium Instituto de Alta Investigación Universidad de Tarapacá Casilla 7D Arica Chile Gemini Observatory/NSF NOIRLab 670 N. A'ohoku Place HiloHI96720 United States Departamento de Ingeniería Topográfica y Cartografía E.

TOI-2015 is a known exoplanetary system around an M4 dwarf star, consisting of a transiting sub-Neptune planet in a 3.35-day orbital period, TOI-2015 b, accompanied by a non-transiting companion, TOI-2015 c. High-precision radial-velocity measurements were taken with the MAROON-X spectrograph, and high-precision photometric data were collected, primarily using the SPECULOOS, MUSCAT, TRAPPIST and LCOGT networks. We collected 63 transit light curves and 49 different transit epochs for TOI-2015 b. We recharacterized the target star by combining optical spectra obtained by the MAROON-X, Shane/KAST and IRTF/SpeX spectrographs, Bayesian model averaging (BMA) and spectral energy distribution (SED) analysis. The TOI-2015 host star is a K = 10.3 mag M4-type dwarf with a subsolar metallicity of [Fe/H] =-0.31 ± 0.16, and an effective temperature of Teff ≈ 3200 K. Our photodynamical analysis of the system strongly favors the 5:3 mean-motion resonance and in this scenario the planet b (TOI-2015 b) has an orbital period of Pb = 3.34 days, a mass of Mp = 9.02-0.36+0.32M⊕, and a radius of Rp = 3.309-0.011+0.013R⊕, resulting in a density of ρp = 0.25 ± 0.01 ρ⊕ = 1.40 ± 0.06 g cm-3;this is indicative of a Neptune-like composition. Its transits exhibit large (> 1 hr) timing variations characteristic of an outer perturber in the system. We performed a global analysis of the high-resolution radial-velocity measurements, the photometric data, and the TTVs, and inferred that TOI-2015 hosts a second planet, TOI-2015 c, in a non-transiting configuration. Our analysis places it near a 5:3 resonance with an orbital period of Pc = 5.583 days and a mass of Mp = 8.91-0.40+0.38M⊕. The dynamical configuration of TOI-2015 b and TOI-2015 c can be used to constrain the system's planetary formation and migration history. Based on the mass-radius composition models, TOI-2015 b is a water-rich or rocky planet with a hydrogen-helium envelope. Moreover, TOI-2015 b has a high transmission-spectroscopic met

关键词： Velocity measurement

来源：评论

学校读者我要写书评

暂无评论

Empowering Precision Medicine: AI-Driven Schizophrenia Diagnosis via EEG Signals: A Comprehensive Review from 2002-2023

arXiv

引用

arXiv 2023年

作者： Jafari, Mahboobeh Sadeghi, Delaram Shoeibi, Afshin Alinejad-Rokny, Hamid Beheshti, Amin García, David López Chen, Zhaolin Acharya, U. Rajendra Gorriz, Juan M. Internship in BioMedical Machine Learning Lab The Graduate School of Biomedical Engineering UNSW Sydney SydneyNSW2052 Australia Data Science and Computational Intelligence Institute University of Granada Spain BioMedical Machine Learning Lab The Graduate School of Biomedical Engineering UNSW Sydney SydneyNSW2052 Australia UNSW Data Science Hub The University of New South Wales SydneyNSW2052 Australia Health Data Analytics Program Centre for Applied Artificial Intelligence Macquarie University Sydney2109 Australia Data Science Lab School of Computing Macquarie University SydneyNSW2109 Australia Monash University Melbourne Australia School of Mathematics Physics and Computing University of Southern Queensland Springfield Australia Department of Psychiatry University of Cambridge United Kingdom

Schizophrenia (SZ) is a prevalent mental disorder characterized by cognitive, emotional, and behavioral changes. Symptoms of SZ include hallucinations, illusions, delusions, lack of motivation, and difficulties in concentration. While the exact causes of SZ remain unproven, factors such as brain injuries, stress, and psychotropic drugs have been implicated in its development. SZ can be classified into different types, including paranoid, disorganized, catatonic, undifferentiated, and residual. Diagnosing SZ involves employing various tools, including clinical interviews, physical examinations, psychological evaluations, the Diagnostic and Statistical Manual of Mental Disorders (DSM), and neuroimaging techniques. Electroencephalography (EEG) recording is a significant functional neuroimaging modality that provides valuable insights into brain function during SZ. However, EEG signal analysis poses challenges for neurologists and scientists due to the presence of artifacts, long-term recordings, and the utilization of multiple channels. To address these challenges, researchers have introduced artificial intelligence (AI) techniques, encompassing conventional machine learning (ML) and deep learning (DL) methods, to aid in SZ diagnosis. This study reviews papers focused on SZ diagnosis utilizing EEG signals and AI methods. The introduction section provides a comprehensive explanation of SZ diagnosis methods and intervention techniques. Subsequently, review papers in this field are discussed, followed by an introduction to the AI methods employed for SZ diagnosis and a summary of relevant papers presented in tabular form. Additionally, this study reports on the most significant challenges encountered in SZ diagnosis, as identified through a review of papers in this field. Future directions to overcome these challenges are also addressed. The discussion section examines the specific details of each paper, culminating in the presentation of conclusions and findings. © 2023,

关键词： Electroencephalography

来源：评论

学校读者我要写书评

暂无评论

Evolutionary Design of an Isothermal Double Y-Shaped Cavity

SSRN

引用

SSRN 2023年

作者： Gonzales, Gill Velleda Biserni, Cesare Oliveira Rocha, Luiz Alberto Isoldi, Liércio André da Silva Diaz Estrada, Emanuel da Silva Neto, Antônio José dos Santos, Elizaldo Domingues Graduate Program of Computational Modeling Federal University of Rio Grande - FURG RS Rio GrandeCEP 96201-900 Brazil Federal Institute of Education Science and Technology Sul-Rio-Grandense Pelotas Campus RS PelotasCEP 96015-360 Brazil Alma Mater Studiorum - University of Bologna Viale Risorgimento 2 Bologna40136 Italy Polytechnic Institute Rio de Janeiro State University RJ Nova Friburgo28625-570 Brazil

This work deals with constructal design (CD) for the geometrical investigation of a complex cavity in the form of double Y inserted for chilling a rectangular heat-generating solid body. The purpose is to minimize the dimensionless maximum temperature excess in the solid domain for the geometry with four constraints and seven degrees of freedom (DOF). The optimization process is performed with exhaustive search (ES) and differential evolution (DE) apart for the first three investigated DOFs to validate the metaheuristic application. From the fourth DOF onward, an association of the two methods (ES and DE) is employed to reproduce the effect of the analyzed DOFs on the performance indicator and design. For square solids, the optimal geometries were obtained when the branches of the investigated cavity were stretched, covering the solid body and distributing more homogeneously the hot regions, i.e., following the optimal distribution of imperfections principle. Moreover, the performance of the new cavity was higher than other configurations (I, T, Y, X, H, and double T) and similar to the ψ-shaped cavity previously studied in the literature. For low and high height/length (H/L) ratios of the solid domain, the optimal configurations were obtained when the double Y-shaped cavity changed to double T and I configurations, respectively, showing the impact of the constraints on the design of the cavity. © 2023, The Authors. All rights reserved.

关键词： Optimization

来源：评论

学校读者我要写书评

暂无评论

Automated Generation of Narrative Sleep Reports Utilizing Portable Electroencephalogram Data Through ChatGPT

Automated Generation of Narrative Sleep Reports Utilizing Po...

引用

IEEE International Conference on Healthcare Informatics (ICHI)

作者： Saki Tsumoto Fusae Kawana Kazumasa Horie Minori Masaki Kei Nishida Kazuya Miyanishi Jaehoon Seol Morie Tominaga Takashi Amemiya Tetsuro Hiei Akihiro Tani Masaki Matsubara Atsuyuki Morishima Hiroyuki Kitagawa Masashi Yanagisawa Ph.D. Program in Humanics University of Tsukuba Tsukuba Japan Juntendo University Graduate School of Medicine Tokyo Japan Center for Computational Sciences (CCS) University of Tsukuba Tsukuba Japan Faculty of Health and Sports Sciences University of Tsukuba Tokyo Japan S ‘ UIMIN Inc Tokyo Japan Institute of Library Information and Media Science University of Tsukuba Tsukuba Japan International Institute for Integrative Sleep Medicine (WPI-IIIS)) University of Tsukuba Tsukuba Japan

ISBN: (数字)9798350383737

ISBN: (纸本)9798350383744

Sleep is a very important activity, but many people do not know their own sleep conditions. A sleep test personalizes sleep quality assessment and detects potential sleep disorders by measuring biological signals. The rise in sleep-related issues has necessitated the development of automated testing methods. Machine learning plays a pivotal role in interpreting sleep data and determining sleep stages. However, the generation of detailed reports and tailored recommendations still demands expert intervention. Automating the report generation to provide personalized sleep insights is a crucial and desired step for the future of sleep healthcare. Recently emerged Generative AI, such as ChatGPT, has attracted considerable attention in recent years. It can generate new sentences and images from input data. In this study, we investigate the practicality and applicability of using ChatGPT to generate narrative sleep reports for sleep test. In our proposed method, GPT-4 receives the information about the sleep habits of the participants and the sleep assessment automatically summarized by the rule-based algorithm. In the evaluation, we used in-home sleep EEG data obtained from 100 subjects by S'UIMIN inc. The generated reports were evaluated by experienced technicians and physicians on a 5- point scale for medical correctness and appropriateness as informative reports. The results of the evaluation showed that 60 % of the reports were the acceptable or above range in both aspects. While more than half of the results were judged to be above the acceptable range, differences between the generative AI and humans were also identified. Whereas humans comment on semantically weighted important findings such as medication and subjective insomnia, ChatGPT tends to make broad, shallow and flat comments on the input data. These facts suggest that although practical report generation only using generative AI is at present not easy, generative AI is a promising tool for improving the ef

关键词： Sleep Generative AI Medical services Machine learning Chatbots Electroencephalography Quality assessment

来源：评论

学校读者我要写书评

暂无评论

Variable precision distance search for random fractalcluster simulations

引用

WSEAS Transactions on Computers 2009年第8期8卷 1245-1255页

作者： Antonio, Sosa-Herrera Suemi, Rodriguez-Romo Computational Science Graduate Program Universidad Nacional Autónoma de México Campus Cuautitlán Av. 1 de Mayo s/n. Col.Atlanta 54740 Cuautitlán Izcalli Edo. Mex. Mexico Center of Theoretical Research Universidad Nacional Autónoma de México Campus Cuautitlán Av. 1 de Mayo s/n. Col.Atlanta 54740 Cuautitlán Izcalli Edo. Mex. Mexico

A simple an effective algorithm for performing distance queries between a large number of points stored in quadtrees and octrees. The algorithm is developed and tested for the construction of diffusion-limited aggregates. To achieve an enhancement on the searching time we accept approximate distance values with low precision at the first levels of the hierarchical structure, and accurate ones at the last level. The structure of the trees is the only feature used for the determination of approximate distances at any stage. These techniques allowed us to build DLA clusters with up to 109 particles for the two-dimensional case and up to 108 particles for the three-dimensional case. We also worked with the PDLA model obtaining fractal clusters with up to 1010 and 109 particles for two and three dimension clusters respectively. We worked on a supercomputer to run the PDLA simulations, as well as a high performance server for DLA simulations. We employed POSIX threads to provide parallelization and mutexes as control mechanisms to achieve synchronization between groups of 4 processors, hence simulating PDLA clusters with early convergence to the DLA model.

关键词： Supercomputers

来源：评论

学校读者我要写书评

暂无评论

Hypostatic jammed packings of frictionless nonspherical particles

arXiv

引用

arXiv 2017年

作者： VanderWerf, Kyle Jin, Weiwei Shattuck, Mark D. O'Hern, Corey S. Department of Physics Yale University New HavenCT06520 United States Benjamin Levich Institute and Physics Department City College of New York New YorkNY10031 United States Department of Mechanics and Engineering Science Peking University Beijing100871 China Department of Mechanical Engineering & Materials Science Yale University New HavenCT06520 United States Department of Applied Physics Yale University New HavenCT06520 United States Graduate Program in Computational Biology and Bioinformatics Yale University New HavenCT06520 United States

We perform computational studies of static packings of a variety of nonspherical particles including circulo-lines, circulo-polygons, ellipses, asymmetric dimers, dumbbells, and others to determine which shapes form packings with fewer contacts than degrees of freedom (hypostatic packings) and which have equal numbers of contacts and degrees of freedom (isostatic packings), and to understand why hypostatic packings of nonspherical particles can be mechanically stable despite having fewer contacts than that predicted from naïve constraint counting. To generate highly accurate force- and torque-balanced packings of circulo-lines and -polygons, we developed an interparticle potential that gives continuous forces and torques as a function of the particle coordinates. We show that the packing fraction and coordination number at jamming onset obey a master-like form for all of the nonspherical particle packings we studied when plotted versus the particle asphericity A, which is proportional to the ratio of the squared perimeter to the area of the particle. Further, the eigenvalue spectra of the dynamical matrix for packings of different particle shapes collapse when plotted at the same A. For hypostatic packings of nonspherical particles, we verify that the number of "quartic" modes along which the potential energy increases as the fourth power of the perturbation amplitude matches the number of missing contacts relative to the isostatic value. We show that the fourth derivatives of the total potential energy in the directions of the quartic modes remain nonzero as the pressure of the packings is decreased to zero. In addition, we calculate the principal curvatures of the inequality constraints for each contact in circulo-line packings and identify specific types of contacts with inequality constraints that possess convex curvature. These contacts can constrain multiple degrees of freedom and allow hypostatic packings of nonspherical particles to be mechanically stable. C

关键词： Degrees of freedom (mechanics)

来源：评论

学校读者我要写书评

暂无评论

Theoretical insights into the chemical bonding, electronic structure, and spectroscopic properties of the lanarkite Pb2SO5 structure

arXiv

引用

arXiv 2023年

作者： Fabris, Guilherme S.L. Ferrer, Mateus M. Sambrano, Julio R. Almeida, Cláudio R.R. Paskocimas, Carlos A. La Porta, Felipe A. Graduate Program in Materials Science and Engineering Technological Development Center Universidade Federal de Pelotas RS Pelotas96010-610 Brazil Modeling and Molecular Simulation Group São Paulo State University Bauru São Paulo17033-360 Brazil Department of Materials Engineering Federal University of Rio Grande do Norte RN Natal59078-970 Brazil Postgraduate Program in Science and Engineering of Materials Federal University of Rio Grande do Norte RN Natal59078-970 Brazil Federal University of Technology - Paraná Nanotechnology and Computational Chemistry Laboratory Avenida dos Pioneiros 3131 CEP PR Londrina86036-370 Brazil State University of Londrina Post-Graduation Program in Chemistry Rodovia Celso Garcia Cid 445 km 380 CEP PR Londrina86057-970 Brazil

Lanarkite is a mineral formed by a combination of lead, sulphur, and oxygen atoms arranged in the general chemical formula Pb2SO5 (PSO) that crystallises with monoclinic symmetry (belonging to the C2/m space group, No. 12). This mineral was first discovered in Lanarkshire, Scotland and was named after its location. PSO has a unique structure comprising alternating penta-coordinated lead [PbO5] and tetra-coordinated sulphur [SO4] clusters. This lanarkite-type structure has recently attracted significant scientific interest and has been the focus of the superconducting material research community. However, its chemistry needs to be explored further. This article presents a comprehensive investigation on the chemical bonding, electronic structure, and spectroscopic properties of the lanarkite-type PSO structure from a computational perspective. Thus, different functionals in the DFT (e.g., PBE, PBE0, PBESOL, PBESOL0, BLYP, WC1LYP37, and B3LYP) were assessed to accurately predict their fundamental properties. All the DFT calculations were performed using a triple-zeta valence plus polarisation basis set. Among all the DFT functionals tested in this study, PBE showed the best agreement with the experimental data available in the literature. Our results also reveal that the [PbO5] clusters are formed with three Pb–O bond lengths, with values of about 2.32, 2.59, and 2.84 Å, respectively, while the [SO4] clusters have the same S–O bond length of 1.57 Å. We performed a complete topological analysis of this system to comprehend these structural differences. Additionally, the PSO structure has an indirect band gap energy of 2.9 eV and an effective mass ratio (mℎ∗ /me∗) of about 0.415 (using PBE calculations) which may, in principle, indicate a low recombination of electron-hole pairs in the lanarkite structure. Therefore, we believe that a detailed understanding of their electronic structures, spectroscopic properties as well as their chemical bonding is critically important

关键词： Lead compounds

来源：评论

学校读者我要写书评

暂无评论

Theoretical study on adsorption and reaction of polymeric formic acid on the Cu(111) surface

引用

Physical Review Materials 2021年第7期5卷 075801-075801页

作者： Septia Eka Marsha Putra Fahdzi Muttaqien Yuji Hamamoto Kouji Inagaki Akitoshi Shiotari Jun Yoshinobu Yoshitada Morikawa Ikutaro Hamada Department of Precision Engineering Graduate School of Engineering Osaka University 2-1 Yamada-oka Suita Osaka 565-0871 Japan Department of Engineering Physics Institut Teknologi Sumatera Jalan Terusan Ryacudu Way Hui Jati Agung South Lampung 35365 Indonesia Instrumentation and Computational Physics Research Group Faculty of Mathematics and Natural Sciences Institut Teknologi Bandung Jalan Ganesha 10 Bandung West Java 40132 Indonesia Master Program in Computational Science Faculty of Mathematics and Natural Sciences Institut Teknologi Bandung Jalan Ganesha 10 Bandung West Java 40132 Indonesia Elements Strategy Initiative for Catalysts and Batteries (ESICB) Kyoto University Goryo-Ohara Nishikyou-ku Katsura Kyoto 615-8245 Japan Department of Advanced Materials Science The University of Tokyo 5-1-5 Kashiwanoha Kashiwa Chiba 277-8561 Japan The Institute for Solid State Physics The University of Tokyo 5-1-5 Kashiwanoha Kashiwa Chiba 277-8581 Japan Research Center for Precision Engineering Graduate School of Engineering Osaka University 2-1 Yamada-oka Suita Osaka 565-0871 Japan

We investigate the polymeric adsorption of formic acid (HCOOH) on the Cu(111) surface by means of density functional theory. We present structural models for the polymeric form of HCOOH on Cu(111) and characterize their stability, electronic, and vibrational properties. Based on the energetics and dynamics, as well as simulated scanning tunneling microscopy and atomic force microscopy images, we propose that the α polymorph is likely to be formed on the Cu(111) surface and can explain the experimental findings. We also study the initial step of the catalytic dehydrogenation of HCOOH and find that the O-H bond dissociation at the edge of the polymer is facilitated, rather than that forming hydrogen bonding, agreeing well with the experiments.

关键词： Adsorption Chemical bonding Chemical kinetics, dynamics & catalysis Electronic structure Surface & interfacial phenomena Surfaces Density functional theory First-principles calculations

来源：评论

学校读者我要写书评

暂无评论

Characterizing the mechanical response of metallic glasses to uniaxial tension using a spring network model

arXiv

引用

arXiv 2023年

作者： Nawano, Aya Schroers, Jan Shattuck, Mark D. O’Hern, Corey S. Department of Mechanical Engineering and Materials Science Yale University New HavenCT06520 United States Benjamin Levich Institute and Physics Department The City College of New York New YorkNY10031 United States Department of Physics Yale University New HavenCT06520 United States Department of Applied Physics Yale University New HavenCT06520 United States Graduate Program in Computational Biology and Bioinformatics Yale University New HavenCT06520 United States

Metallic glasses are frequently used as structural materials. Therefore, it is important to develop methods to predict their mechanical response as a function of the microstructure prior to loading. We develop a novel coarse-grained spring network model, which describes the mechanical response of metallic glasses using an equivalent series network of springs, which can break and re-form to mimic atomic rearrangements during deformation. To validate the spring network model, we perform numerical simulations of quasistatic, uniaxial tensile deformation of Lennard-Jones and embedded atom method (EAM) potentials for Cu50Zr50 metallic glasses in the absence of large-scale shear band formation. We consider samples prepared using a wide range of cooling rates and with different amounts of crystalline order. We show that both the Lennard-Jones and EAM models possess qualitatively similar stress σ versus strain γ curves. By specifying five parameters in the spring network model (ultimate strength, strain at ultimate strength, slopes of σ(γ) at γ = 0 and at large strain, and strain at fracture where σ = 0), we can accurately describe the form of the stress-strain curves during uniaxial tension for the computational studies of Cu50Zr50, as well as recent experimental studies of several Zr-based metallic glasses. For the computational studies of Cu50Zr50, we find that the yield strain distribution is shifted to larger strains for slowly cooled glasses compared to rapidly cooled glasses. In addition, the average number of new springs and their rate of formation decreases with decreasing cooling rate. These effects offset each other at large strains, causing the stress-strain curve to become independent of the sample preparation protocol in this regime. In future studies, we will extract the parameters that define the spring network model directly from atomic rearrangements that occur during uniaxial deformation. © 2023, CC BY-NC-ND.

关键词： Metallic glass

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：