bluuebunny/crossref_metadata_2025_split huggingface dataset:
The role of chemical and microstructural inhomogeneities on interface magnetism
Authors: Laureti S , Gerardino A , D’Acapito F , Peddis D , Varvaro G 
Published: February 2021

Abstract
The study of interfacing effects arising when different magnetic phases are in close contact has led to the discovery of novel physical properties and the development of innovative technological applications of nanostructured magnetic materials. Chemical and microstructural inhomogeneities at the interfacial region, driven by interdiffusion processes, chemical reactions and interface roughness may significantly affect the final properties of a material and, if suitably controlled, may represent an additional tool to finely tune the overall physical properties. The activity at the Nanostructured Magnetic Materials Laboratory (nM2-Lab) at CNR-ISM of Italy is aimed at designing and investigating nanoscale-engineered magnetic materials, where the overall magnetic properties are dominated by the interface exchange coupling. In this review, some examples of recent studies where the chemical and microstructural properties are critical in determining the overall magnetic properties in core/shell nanoparticles, nanocomposites and multilayer heterostructures are presented.
Antiferromagnetic skyrmion repulsion based artificial neuron device
Authors: Bindal Namita , Ian Calvin Ang Chin , Lew Wen Siang , Kaushik Brajesh Kumar 
Published: February 2021

Abstract
Magnetic skyrmions are potential candidates for neuromorphic computing due to their inherent topologically stable particle-like behavior, low driving current density, and nanoscale size. Antiferromagnetic skyrmions are favored as they can be driven parallel to in-plane electrical currents as opposed to ferromagnetic skyrmions which exhibit the skyrmion Hall effect and eventually cause their annihilation at the edge of nanotracks. In this paper, an antiferromagnetic skyrmion based artificial neuron device consisting of a magnetic anisotropy barrier on a nanotrack is proposed. It exploits inter-skyrmion repulsion, mimicking the integrate-fire (IF) functionality of a biological neuron. The device threshold represented by the maximum number of skyrmions that can be pinned by the barrier can be tuned based on the particular current density employed on the nanotrack. The corresponding neuron spiking event occurs when a skyrmion overcomes the barrier. By raising the device threshold, lowering the barrier width and height, the operating current density of the device can be decreased to further enhance its energy efficiency. The proposed device paves the way for developing energy-efficient neuromorphic computing in antiferromagnetic spintronics.
Bottom-up field-directed self-assembly of magnetic nanoparticles into ordered nano- and macrostructures
Authors: Preger Calle , Josefsson Martin , Westerström Rasmus , Messing Maria E 
Published: February 2021

Abstract
Directed self-assembly of nanoparticles (NPs) is a promising strategy for bottom-up fabrication of nanostructured materials with tailored composition and morphology. Here, we present a simple and highly flexible method where charged magnetic aerosolized (i.e. suspended in a gas) NPs with tunable size and composition are self-assembled into nanostructures using combined electric and magnetic fields. Size-selected Co, Ni, and Fe NPs have been generated by spark ablation, and self-assembled into different structures, ranging from one-dimensional nanochains to macroscopic three-dimensional networks. By comparing the resulting structures with simulations, we can conclude that the magnetization of the NPs governs the self-assembly through interparticle magnetic dipole−dipole interactions. We also show how the orientation of the external magnetic field directs the self-assembly into differently aligned nano- and macroscopic structures. These results demonstrate how aerosol deposition in a combined electric and magnetic field can be used for directed bottom-up self-assembly of nanostructures with specialized composition and morphology.
An enhancement on supercapacitor properties of porous CoO nanowire arrays by microwave-assisted regulation of the precursor
Authors: Sun Yin , Zhang Junjie , Liu Sen , Sun Xiannian , Huang Naibao 
Published: February 2021

Abstract
A microwave-assisted hydrothermal approach with a follow up thermal treatment was employed to prepare 1D porous CoO nanowires, which is constructed by numerous high crystallinity nanoparticles. A significant change in crystal structure of the precursor were observed, as position shift and absence of some diffraction peaks, which was induced by the microwave-assistance during hydrothermal process. Moreover, the precursor’s purity was also effectively improved. As a result, the as-synthesized CoO annealed from the microwave-assisted precursor exhibited a morphology and phase structure significantly different from that of without microwave involvement. Benefiting from the ‘microwave effect’, the microwave-assisted as-fabricated porous CoO nanowires showed an enhanced specific capacitance (728.8 versus 503.7 F g−1 at 1 A g−1 ), strengthened rate performance (70.0% versus 53.2% maintenance at 15 A g−1), reduced charge transfer resistance (1.06 Ω versus 2.39 Ω), enlarged window voltage (0.85 versus 0.7 V) and enhanced cycle performance (82.3% versus 76.5% retention after 5000 cycles at 15 A g−1), compared with that of sample without microwave assistance. In addition, the corresponding electrochemical properties are also higher than those reported CoO sample prepared by solvothermal method. In conclusion, this work provides a practical way for enhancing electrochemical properties of supercapacitor materials through adjusting the precursor by microwave assistance into hydrothermal process.
Improved performance of fluorescent/phosphorescent hybrid white organic light-emitting diodes with enhanced chromatic stability utilizing bipolar interlayer
Authors: Chen Ruilin , Zhu Wenqing , Huang Lu , Luo Yun , Li Jun 
Published: February 2021

Abstract
Fluorescent/phosphorescent hybrid white organic light-emitting diodes (WOLEDs) employing a bipolar CBP interlayer with different thickness have been fabricated. The two-color hybrid WOLEDs at the optimal interlayer thickness exhibit a maximum efficiency of 11.47 cd A−1. Compared with the device without a CBP interlayer, the efficiency of the device is increased by 38.5% and the chromatic stability is also improved. This work found that appropriate thickness of the CBP interlayer with a higher triplet energy level can effectively block the Dexter energy transfer between the phosphorescent and fluorescent layers, which can reduce the energy of triplet in the exciton recombination zone and improve the efficiency of the device. Furthermore, the introduction of the bipolar interlayer with a suitable energy level adjusts the balance of exciton distribution, thereby achieving white light emission with good color stability. The present research could provide valuable strategy in developing hybrid WOLEDs with stable chromaticity.
Defect states and passivation mechanism at grain boundaries of zinc-blende semiconductors
Authors: Gu Hong-Yang , Yin Wan-Jian , Gong Xin-Gao 
Published: February 2021

Abstract
Grain boundaries (GBs) are significant in determining the electrical properties of polycrystalline semiconductors. However, the electronic structures and passivation mechanisms of polycrystalline semiconductors remain poorly understood. In this study, we systematically investigated the Σ3 (112) GB properties of several typical zinc-blende semiconductors via first-principles density functional calculations. We found significant differences of Σ3 (112) GB structures and properties between IV/III and V types, where dangling atoms formed new covalent bonds, and II–VI/I–VII types, where dangling atoms formed no new bonds. These different bonding configurations lead to different origins of defect states at GBs. We successfully designed a targeted doping approach to passivate such defect states for different types of semiconductors. We demonstrated the validity of the proposed approach in Σ3 (112) GB of the zinc-blende semiconductors. This work elucidates the defect states at GBs in common zinc-blende semiconductors, rationalizes diverse post-treatment approaches reported in previous experiments, and provides general guidance for defect passivation at the GBs of polycrystalline semiconductors.
Investigation of the non-equilibrium state of strongly correlated materials by complementary ultrafast spectroscopy techniques
Authors: Hedayat H , Sayers C J , Ceraso A , van Wezel J , Clark S R , Dallera C , Cerullo G , Da Como E , Carpene E 
Published: February 2021

Abstract
Photoinduced non-thermal phase transitions are new paradigms of exotic non-equilibrium physics of strongly correlated materials. An ultrashort optical pulse can drive the system to a new order through complex microscopic interactions that do not occur in the equilibrium state. Ultrafast spectroscopies are unique tools to reveal the underlying mechanisms of such transitions which lead to transient phases of matter. Yet, their individual specificities often do not provide an exhaustive picture of the physical problem. One effective solution to enhance their performance is the integration of different ultrafast techniques. This provides an opportunity to simultaneously probe physical phenomena from different perspectives while maintaining the same experimental conditions. In this context, we performed complementary experiments by combining time-resolved reflectivity and time and angle-resolved photoemission spectroscopy. We demonstrate the advantage of this combined approach by investigating the complex charge density wave (CDW) phase in 1T-TiSe2. Specifically, we show the key role of lattice degrees of freedom to establish and stabilize the CDW in this material.
Refractive index gas thermometry between 13.8 K and 161.4 K
Authors: Ripa D Madonna , Imbraguglio D , Gaiser C , Steur P P M , Giraudi D , Fogliati M , Bertinetti M , Lopardo G , Dematteis R , Gavioso R M 
Published: February 2021

Abstract
We have measured the refractive index of helium using a quasi-spherical copper microwave resonator at five different temperatures in the interval between the triple point of hydrogen at 13.8 K and the triple point of xenon at 161.4 K for pressures up to 380 kPa. From these results and additional measurements of the refractive index of neon near 54.4 K, 83.8 K and 161.4 K we determine the differences (T − T
90) between the thermodynamic temperature T and its approximation T
90 by the International Temperature Scale of 1990 (ITS-90). We have estimated the isothermal compressibility of copper and the effective compressibility of our microwave resonator by different methods including resonant ultrasound spectroscopy (RUS) and microwave measurements with helium at 273.16 K. We compare the results of these compressibility estimates and discuss the associated uncertainty. From the refractive index measurements, we estimate the second density virial coefficient of helium and neon which are found in good agreement with the ab initio calculations of the same properties.
Performance of two redundant quantum channels for single qubits under indefinite causal order
Authors: Cardoso-Isidoro Carlos , Delgado Francisco 
Published: February 2021

Abstract
Indefinite causal order has introduced novel procedures to improve the quality of quantum communication. The superposition of paths on a set of consecutive quantum channels has demonstrated enhancement in communication on some of them. This work models a generic quantum channel for single qubits in terms of Kraus operators in the form of Pauli operators. The output state going through the channel can be obtained analytically to then analyse the quality by means of the quantum fidelity.
Einstein field equations for Bose-Einstein condensates in cosmology
Authors: Roitberg Alice 
Published: February 2021

Abstract
In this work we consider the Gross-Pitaevskii equation for Bose-Einstein condensates (BECs) in a general Riemannian metric. Given initial conditions dictated by an external potential, we consider the free expansion of the condensate when the external potential is turned off. Focusing on the forces associated with the geometry of the initial configuration, we show how these are related to the Ricci curvature tensor and the Ricci scalar and we find an Einstein field equation governing the steady flow. Some important correlations between the study of defects in BECs and the appearance of cosmological singularities will be addressed, in particular the emergence of an effective Lorentzian spacetime geometry, which is what is needed to obtain Hawking radiation effects.
gravity with scalar field viscous fluid
Authors: Myrzakul S R , Imankul M , Arzimbetova M , Myrzakul T R 
Published: February 2021

Abstract
We focus on a viable teleparallel cosmological model with a scalar field in a flat Friedman-Robertson-Walker universe. The Lagrangian and equations of motion are obtained. The case of an inhomogeneous viscous dark energy is considered and the cosmological parameters associated with the viscosity parameter are determined. It is shown that when considering constant viscosity and state parameter, the Universe expands exponentially
Influence of clustering round magnetic nano-dots on magnetization reversal
Authors: Blachowicz T , Ehrmann A 
Published: February 2021

Abstract
Square and round magnetic nano-dots of varying dimensions exhibit a large amount of possible magnetization reversal processes, from domain wall nucleation and propagation to multi-vortex states. Clustering such single nano-dots, however, may strongly modify these magnetization reversal processes due to the interactions between neighboring particles. Here we thus investigate the difference between magnetization reversal processes in clusters of hexagonally arranged round nano-dots under different orientations of the external magnetic field in comparison with single particle behavior.
New open computational resource for plasma processes modelling
Authors: Zhilkin A S , Sychugov D Yu , Vysotsky L I , Zotov I V , Soloviev S Yu , Sadykov A D 
Published: February 2021

Abstract
The paper describes a new open access computing resource nfusion.cs.msu.ru. The resource includes modules for calculating equilibrium, vertical stability, plasma evolution, simulation systems for magnetic diagnostics, as well as a new algorithm for constructing three-dimensional tetrahedral meshes in areas of complex structure. The modules are integrated into a unified software environment designed for numerical support of experiments on tokamak installations. The possibility of accessing the calculation modules on the server via the Internet, data exchange and the issuance of calculation results in the form of files, figures, and tables has been implemented. The resource supports the simultaneous operation of several users and has an information support system in Russian and English.
Multi-fidelity sparse polynomial chaos expansion based on Gaussian process regression and least angle regression
Authors: Xiao Dong , Ferlauto Michele , Song Liming , Li Jun 
Published: February 2021

Abstract
Polynomial chaos (PC) expansion meta-model has been wildly employed and investigated in the field of uncertainty quantification (UQ) and sensitivity analysis (SA). However, the majority of the multi-fidelity polynomial chaos expansion (MF-PC) models in the literature are still focused on using high-fidelity (HF) PC model to correct low fidelity (LH) model directly, without cross-correlation between PC models of different fidelities. To address this shortcoming, a multi-fidelity sparse polynomial chaos expansion (MF-sPC) model is proposed based on least angle regression (LAR) and recursive Gaussian process regression (GPR) in this paper. From low to high degree of fidelity, the autoregressive scheme in MF GPR is employed to construct MF-sPC model, in which the sparse polynomial chaos (sPC) model of each fidelity is built iteratively coupling with GPR, LAR and cross validation (CV), as gradually expanding the design of experiment (DoE) to reach a given CV error. This recursive scheme finally yields a MF-sPC model with highest fidelity which takes advantage of all sPC models of the lower fidelities. And the proposed MF-sPC model is validated by a test example in detail, and the results reveal that this MF meta-model performs outstanding both in convergence speed and model accuracy.
About Identifiability of Oil and Water Relative Permeability Curves and Reservoir Heterogeneity through Integrated Well Test Study
Authors: Zakirov E S , Anikeev D P , Indrupskiy I M , Tsagan-Mandzhiev T N , Alekseeva Yu V 
Published: February 2021

Abstract
Relative permeabilities (RP) play an important role in reservoir engineering. RP functions together with the permeability anisotropy coefficient predetermine waterflooding efficiency and oil/water ratio in production forecast. Traditionally multiphase flow parameters are estimated from core analysis data. But such measurements suffer from small representative elementary volume (REV) and limited characterization of reservoir properties. Therefore using core data in 3D reservoir modelling could lead to distorted description of actual flow conditions. Despite those functions (RP) could be history matched with assimilated production data, such a procedure would require long history of waterflooding. So the authors’ idea is to apply integrated well test study to estimate the displacement efficiency and/or relative permeability functions at downhole conditions. Well testing is traditionally applied in reservoir engineering for single-phase reservoir parameters estimation. Our approach is extended to multi-phase flow and is based on data collection at well bottomholes and subsequent data assimilation in flow model.
In this paper we summarize both features of mathematical problem statement and identifiability of multiphase parameters through inverse problem solution, but also discuss 10+ -year experience in interpretation of two-phase well testing using our technologies. To estimate multiphase parameters, we have to jointly consider complex data of well logging and dynamic data of well testing. Both data sets are used in the inverse problem quality criteria, where the least squares method has been applied. Forward problem corresponds to a 3D multiphase fluid flow model in porous media. The latter consists of continuity equation with multiphase Darcy equation instead of moment balances. For data assimilation modern methods of optimal control theory were successfully applied. For all synthetic test cases real reservoir parameters were accurately recovered through the use of forward simulation data.
In order to estimate reservoir heterogeneity, we applied a single-phase model to get the ratio of vertical to horizontal permeability. Data of well self-interference testing were used for vertical permeability estimation. Depending on the depth of reservoir pressure perturbation, reservoir properties could be properly inferred from observations. Two other options of 3D interference testing using vertical and horizontal wells are also presented.
In other words, all the problems considered are identifiable, and the level of their correctness is completely predetermined by the amount and quality of observed data. And transition to digital (intelligent) oil-and-gas production and closed-loop reservoir management [1] provides a possibility to remove discussed restrictions and all inverse problems considered should be accounted as fully identifiable.
Numerical studies of the saturated absorption resonances in a nonlinear spectroscopy of the degenerate atomic transitions
Authors: Saprykin E G , Chernenko A A 
Published: February 2021

Abstract
The physical processes forming the saturated absorption resonance spectra at a number of degenerate atomic transitions at their interaction with coherent optical fields and incoherent ield of spontaneous radiation of excited atoms are studied numerically. The features of behavior of nonlinear resonance spectra depending on the degree of degeneration and relaxation parametersof level transitions, character of polarizations and intensities, as well as direction of propagation of optical fields are analyzed.
Application of Convolutional Neural Networks in Neutrino Physics
Authors: Novotný Adam , Franc Jiří 
Published: February 2021

Abstract
Convolutional neural networks (CNNs), as a deep learning algorithm, have successfully been used for analyzing visual image data over the past years. As some of the physical experiments can produce image-like data, it is more than fitting to combine the interdisciplinary knowledge between high energy physics and deep learning. Especially in the domain of neutrino physics, the particle classification problem has played an important role and CNNs have shown exceptional results for the image classification. In this paper, results of application of CNN called SE-ResNET on Monte Carlo simulated image data is presented. These visual images are tailored to fit measured data from future Deep Underground Neutrino Experiment. The image classification focuses primarily on neutrino flavor classification, namely on classification of charged current (CC) electron νe
, CC muon νμ
, CC tauon ντ
and neutral current (NC); and secondarily on other characteristics of the image, such as whether the observed particle is neutrino or antineutrino. The results are important for further physical analysis of the neutrino experiment event, e.g. for study of neutrino oscillation.
Expected Performance of a Mobile e-nose platform for Real Time Victim Localization
Authors: Blionas S. 
Published: February 2021

Abstract
In this paper it is presented an analysis for the performance of the sensors of a mobile e-nose system that measures the atmospheric air, gas components’ concentrations (actually CO2 and O2), into a rubble void, where humans are entrapped, after a disastrous event that caused the collapsing of a building/construction. In this case, the entrapped humans in the void, they affect the air composition and temperature into the void. The existence of human(s) creates CO2 source(s), O2 sink(s), and heat source(s) as well (from body temperature). The existence of the entrapped humans constantly affect the air composition and temperature into the void and makes gas components’ concentrations dynamic. There will be presented the human CO2 source(s), and O2 sink(s) inside a cavity. The final goal is to estimate the concentrations of CO2 and O2 into the cavity as a function of time, having as parameters the number of entrapped humans. Estimating the concentrations it will enable the operator of a mobile e-nose system with sensors of a specific sensitivity and specificity, to determine the possibilities of detecting the presence of humans in a rubble void, nevertheless without considering the effect of weather conditions.
A new decomposition law for inverses modular multiplicative on (ℤ/ϱℤ)
Authors: Cortés–Vega Luis A. 
Published: February 2021

Abstract
In modular arithmetic, we find a valuable concept, the so-called “modular multiplicative inverse” (symbolized by MMI). In precise words, if ℤ/ϱℤ denoted the residue system modulo ϱ, the (MMI) of a
∈ ℤ/ϱℤ, if it exists, is a

−1
∈ ℤ/ϱℤ, such that

a
×

a

−
1

≡
1

mod
ϱ

, where p ≡ q mod ϱ is the usual modular representation of q
∈ ℤ/ϱℤ. This very special element it is one of the most wideley used mathematical concept in science, engineering and subject areas include the particle physics, the analysis and design of algorithms, data structures, databases, and computer architecture. In this paper, we establish a promising decomposition law for (MMI). In this respect, the main purpose of this paper it is shown that it is possible to express the (MMI) in terms of certain modular multiplicative inverse operators (MMIO) all, well-defined on Group of units pre-established. The main point to note here is that the result of this paper, which expands a result originally presented in [3], does not include any special conditions on the parameters involved.