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Extracting structural motifs from pair distribution function data of nanostructures using explainable machine learning

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npj Computational Materials 2022年第1期8卷 2053-2063页

作者： Andy s.Anker emil t.s.kjær Mikkel Juelsholt troels Lindahl Christiansen susanne Linn skjærvø Mads ry Vogel Jørgensen Innokenty Kantor Daniel risskov sørensen simon J.L.Billinge raghavendra selvan Kirsten M.Ø.Jensen Department of Chemistry and Nano-science Center University of Copenhagen2100CopenhagenDenmark Department of Materials University of OxfordParks RoadOxfordUK Department of Chemistry&iNANO Aarhus University8000AarhusDenmark MAX IV Laboratory Lund University22484LundSweden Department of Physics Technical University of Denmark2880LyngbyDenmark Department of Applied Physics and Applied Mathematics Columbia UniversityNew YorkNY10027USA Condensed Matter Physics and Materials science Department Brookhaven National LaboratoryUptonNY11973USA Department of Computer science University of Copenhagen2100CopenhagenDenmark Department of Neuroscience University of Copenhagen2200CopenhagenDenmark

Characterization of material structure with X-ray or neutron scattering using *** Distribution Function(PDF)analysis most often rely on refining a structure model against an experimental ***,identifying a suitable model is often a ***,automated approaches have made it possible to test thousands of models for each dataset,but these methods are computationally expensive and analysing the output,*** structural information from the resulting fits in a meaningful way,is *** Machine Learning based Motif Extractor(ML-MotEx)trains an ML algorithm on thousands of fits,and uses sHAP(sHapley Additive exPlanation)values to identify which model features are important for the fit *** use the method for 4 different chemical systems,including disordered nanomaterials and ***-MotEx opens for a type of modelling where each feature in a model is assigned an importance value for the fit quality based on explainable ML.

关键词： explain structural meaningful

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Consistency Conditions for Cone-Beam Ct Data Acquired with a straight-Line source trajectory

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tsinghua science and technology 2010年第1期15卷 56-61页

作者： LEVINE Margo s sIDKY emil Y Department of radiology University of Chicago5841 S.Maryland Ave.ChicagoIL 60637USA

A consistency condition is developed for computed tomography （Ct） projection data acquired from a straight-line X-ray source trajectory. the condition states that integrals of normalized projection data along detector lines parallel to the X-ray path must be equal. the projection data is required to be untruncated only along the detector lines parallel to the X-ray path, a less restrictive requirement compared to Fourier conditions that necessitate completely untruncated data. the condition is implemented numerically on simple image functions, a discretization error bound is estimated, and detection of motion inconsistencies is demonstrated. the results show that the consistency condition may be used to quantitatively compare the quality of projection data sets obtained from different scans of the same image object.

关键词： data redundancy John's equation consistency conditions

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Gauge Inverse Monoids

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Algebra Colloquium 2020年第2期27卷 181-192页

作者： emil Daniel schwab Department of Mathematical sciences The University of Texas at El Paso El PasoTexas 79968USA

the paper introduces a class of inverse(sub)monoids which contains Jones-Lawson’s gauge inverse(sub)*** aim is to give examples and the basic properties of these ***-Lawson’s gauge inverse monoid,as an inverse submonoid of the polycyclic monoid,is the prototype in our development *** generalization leads also to Mea-kin-sapir type results involving bijections between special congruences and special wide inverse submonoids.

关键词： inverse semigroup gauge inverse monoid polycyclic monoid

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region of Interest Imaging for a General trajectory with the rebinned BPF Algorithm

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tsinghua science and technology 2010年第1期15卷 68-73页

作者： sIDKY emil Y Department of radiology University of Chicago5841 S.Maryland AvenueChicagoIL 60637USA

the back-projection-filtration （BPF） algorithm has been applied to image reconstruction for cone-beam configurations with general source trajectories. the BPF algorithm can reconstruct 3-D region- of-interest （rOI） images from data containing truncations. However, like many other existing algorithms for cone-beam configurations, the BPF algorithm involves a back-projection with a spatially varying weighting factor, which can result in the non-uniform noise levels in reconstructed images and increased computation time. In this work, we propose a BPF algorithm to eliminate the spatially varying weighting factor by using a rebinned geometry for a general scanning trajectory. this proposed BPF algorithm has an improved noise property, while retaining the advantages of the original BPF algorithm such as minimum data requirement.

关键词： computed tomography region of interest general trajectory rebinned backprojection-filtration

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recent behavior and possible future evolution of the glacieret in the cirque Golemiya Kazan in the Pirin Mountains under conditions of climate warming

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Journal of Mountain science 2019年第1期16卷 16-29页

作者： Peter NOJArOV emil GACHEV Karsten GrUNEWALD National Institute of Geophysics Geodesy and Geography Bulgarian Academy of Sciences south-West University "Neofit rilski" Leibniz Institute of Ecological Urban and regional Development

this research reveals relationships between climate variables and inter-annual dynamics in the area of the glacieret located in the cirque Golemiya Kazan in the Pirin Mountains. the study period is 1993–2017. the correlations are identified using statistical methods. Also, a statistical model is constructed, including some climate variables as predictors. Despite the evident decrease of the glacieret's size in the period from the 1950 s onwards, the long-term trends for the last decades have been insignificant. the main climatic factors influencing the inter-annual dynamics in the area of the glacieret are air temperature, precipitation, zonal and meridional winds and relative humidity. With respect to the dynamics in the area of the glacieret, the important trends in the different climate variables are those of the warm period air temperatures and zonal(u) wind. they also determine to a great extent its future development by acting in two opposite directions – rising temperatures in the warm period will lead to a rapid decrease of its area by the end of the melting season, while the change of wind directionfrom west to east in the warm period will increase its area. the influence of the zonal wind in the warm period is explained mainly by the location of the glacieret in the cirque. Generally, the glacieret is tilted downwards from west to east. thus, westerly winds facilitate blowing away the snow from the surface of the glacieret, assisting its melting in the warm period. Easterly winds do not have such an effect. the combination of the opposite effects of these two most important climate variables leads to the most likely scenario for the future development of the glacieret, according to which by the middle of this century it is expected to turn into a semi-permanent snow patch, which disappears after some summers, and by the end of the century to completely melt every year before the end of the melting season.

关键词： Climate warming Glacieret Pirin Mountains statistical modeling Glacieret area Projection

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Microscopic theory of light-induced ultrafast skyrmion excitation in transition metal films

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npj Computational Materials 2022年第1期8卷 598-604页

作者： emil Viñas Boström Angel rubio Claudio Verdozzi Max Planck Institute for the structure and Dynamics of Matter Luruper Chaussee 14922761HamburgGermany Center for Computational Quantum Physics(CCQ) The Flatiron Institute162 Fifth AvenueNew YorkNY10010USA Division of Mathematical Physics and EtsF Lund UniversityPO Box 11822100LundSweden

Magnetic skyrmions are topological excitations of great promise for compact and efficient memory ***,to interface skyrmionics with electronic devices requires efficient and reliable ways of creating and destroying such *** this work,we unravel the microscopic mechanism behind ultrafast skyrmion generation by femtosecond laser pulses in transition metal thin *** employ a theoretical approach based on a two-band electronic model,and show that by exciting the itinerant electronic subsystem with a femtosecond laser ultrafast skyrmion nucleation can occur on a 100 fs *** combining numerical simulations with an analytical treatment of the strong s–d exchange limit,we identify the coupling between electronic currents and the localized d-orbital spins,mediated via rashba spin–orbit interactions among the itinerant electrons,as the microscopic and central mechanism leading to ultrafast skyrmion *** results show that an explicit treatment of itinerant electron dynamics is crucial to understand optical skyrmion generation.

关键词： excitation transition topological

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Dual-Energy technique at Low tube Voltages for small Animal Imaging

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tsinghua science and technology 2010年第1期15卷 79-86页

作者： CHO seungryong sIDKY emil Y Department of radiology University of ChicagoChicagoIL 60637USA

We investigate the feasibility of dual-energy method for image contrast enhancement in small animal studies using a low kV X-ray radiographic system. A robust method for X-ray spectrum estimation from transmission measurements, based on expectation-maximization （EM） method, is applied to an X-ray specimen radiographic system for dual energy imaging of a mouse. From transmission measurements of two known attenuators at two different X-ray tube voltages, the X-ray energy spectra are reconstructed using the EM-based method. From the spectra information thus obtained, the transmission data for bone and soft tissue in terms of vadous thicknesses are generated. two polynomial functions of transmission data are then sought for to fit the inverted thicknesses of bone and soft-tissue. scatters in cone-beam projection data acquired at two X-ray energies were corrected. From the scatter-corrected data, a bone thickness map is separated from a soft-tissue thickness map by use of the polynomial functions.

关键词： dual-energy specimen radiography spectrum estimation

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China and the EU as Global Actors:Challenges and Opportunities for Joint Cooperation

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Economic and Political studies 2015年第1期3卷 98-113页

作者： emil KIrCHNEr the Department of Government University of Essex

this paper examines the level of cooperation which China and the EU undertake on global issues,especially with regard to the future roles of international organizations such as the UN,the IMF,the World Bank,the G20,the form and practice of multilateralism,the prospects and direction of a multipolar/core world,and whether the two tend to be partners rather than competitors on issues of climate change and energy *** applies the approach of international security cooperation and relies primarily on documentary evidence(e.g.,communiqués on global or regional governance aspects,issued at EU-China summits or separately by each).this paper argues that the"misunderstanding"on principles between the EU and China is at odds with the growing economic interdependencies between the two *** EU and China,two of the pillars in the emerging multipolar order,have fundamentally opposed attitudes to key aspects of global politics,such as sovereignty and multilateralism,and these differences are bound to create further tensions in the development of global governance regimes in the *** originality of this paper lies in that it moves beyond the traditional form of investigating on how each China and the EU perceive each other in cooperation terms by focusing instead on the level of cooperation both partners pursue with regard to multilateralism and within the activities of international organizations.

关键词： China EU multilateralism global governance securit

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Effect of moisture on the aging behavior of asphalt binder

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International Journal of Minerals,Metallurgy and Materials 2011年第4期18卷 460-466页

作者： tao Ma Xiao-ming Huang Enad Mahmoud emil Garibaldy school of transportation Southeast University Nanjing 210096 China Department of Civil and Environmental Engineering University of Wisconsin-Madison Madison 53706 USA Civil Engineering and Construction Bradley University Peoria 61625 USA

the moisture aging effect and mechanism of asphalt binder during the in-service life of pavement were investigated by laboratory simulating *** aging vessel（PAV） test simulating the long-term aging of binder during the in-service life of pavement was modified to capture the long-term moisture aging effect of *** grade tests including penetration test,soften point test,and ductility test as well as superpavetM performance grade tests including viscosity test,dynamic shear rheometer test,and bending beam rheometer test were conducted to fully evaluate the moisture aging effect of *** transform infrared spectroscopy test and Gel-permeation chromatography test were applied to provide a fundamental understanding of the moisture aging mechanism of *** results indicate that moisture condition can accelerate the aging of asphalt binder and shorten the service life of asphalt *** modified PAV test with moisture condition can well characterize the moisture aging properties of asphalt binder.

关键词： pavement asphalt aging moisture

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Investigation of sparse Data Mouse Imaging Using Micro-Ct with a Carbon-Nanotube-Based X-ray source

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tsinghua science and technology 2010年第1期15卷 74-78页

作者： sIDKY emil Y ZHOU Otto Department of radiology University of Chicago5841 S.Maryland AvenueChicagoIL 60637USA

there has been a renewed interest in algorithm development for image reconstruction from highly incomplete data in computed tomography （Ct）. such algorithms may lead to reduced imaging dose and time, and to the design of innovative configurations tailored to specific imaging tasks. In recent years, a carbon-nanotube （CNt）-based field-emission x-ray source has been developed, which offers easy electronic control of radiation and thus can be an ideal candidate for gated imaging. We have recently proposed algorithms for image reconstruction from fan- and cone-beam data collected at highly sparse angular views through minimization of the total-variation （tV） of the image subject to the condition that the estimated data are consistent with the measured data, In this work, we investigate and demonstrate the application of the tV-minimization algorithm to reconstructing images from mouse data acquired with a CNt-based Ct scanner at a number of views much lower than what is used in conventional Ct imaging. the results demon- strate that the tV-minimization algorithm can yield images with quality comparable to those obtained from a large number of views by use of the conventional algorithms. the significance of the work may lie in that the substantial reduction of projection views promised by the tV-minimization algorithm can be exploited for reducing imaging dose and time or for improving temporal resolution in tasks such as dynamic imaging.

关键词： computed tomography image reconstruction compressed sensing tV minimization

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