bluuebunny/crossref_metadata_2025_split huggingface dataset:
Three-dimensional first principles simulation of a hydrogen discharge
Authors: Chew Junxian , Gibbon Paul , Brömmel Dirk , Wauters Tom , Gribov Yuri , de Vries Peter 
Published: January 2021

Abstract
Townsend discharge theory is commonly used to describe and approximate the ionisation fraction growth rate in the very early phase of plasma initiation in tokamak devices via ohmic breakdown. The prediction of the ionisation fraction growth rate is done most commonly with continuum or kinetic models, which in turn boil down to the relation between the first Townsend’s coefficient α, pressure p and electric field strength E (namely, α/p and E/p). To date there are few computational models that attempt to simulate the ionisation fraction growth rate via explicit modelling of each ionisation event through electron-neutral collisions. This is largely due to the challenge of addressing the exponential growth of charged particles from ionisation processes, combined with the high computational cost of N-body simulation. In this work, a new fully three-dimensional, first-principles model of a Townsend hydrogen discharge is demonstrated and benchmarked against prior experimental findings. These tests also include comparisons of three separate models for the scattering angle and their impact on the obtained α/p and mean electron drift velocity. It is found that isotropic scattering combined with restricting the freed electron’s scattering angle along the incident electron’s velocity vector during ionisation events gives the closest agreement of α/p compared to experimental measurements.
Jet quenching and medium response in high-energy heavy-ion collisions: a review
Authors: Cao Shanshan , Wang Xin-Nian 
Published: January 2021

Abstract
Jet quenching has been used successfully as a hard probe to study properties of the quark–gluon plasma (QGP) in high-energy heavy-ion collisions at both the relativistic heavy-ion collider and the large hadron collider. We will review recent progresses in theoretical and phenomenological studies of jet quenching with jet transport models. Special emphasis is given to effects of jet-induced medium response on a wide variety of experimental observables and their implications on extracting transport properties of the QGP in heavy-ion collisions.
Majorana bound state manipulation by current pulses
Authors: Lankhorst Martijn , Jansen Thies , Brinkman Alexander , Golubov Alexander 
Published: January 2021

Abstract
Majorana bound states (MBSs) can occur in Josephson junctions of conventional s-wave superconductors coupled via a strong topological insulator. In configurations of multiple line junctions meeting at a point, the criterion for the MBS to exist coincides with the presence of a fractional Josephson vortex with 2π phase winding. We investigate the dynamic stability of such vortices in arrays of tri- and quad-junctions. The existence of fractional vortices in arrays is demonstrated, but the dynamic stability is found to depend critically on the current-phase relation and the inductance. We propose the idea, and study the feasibility, of manipulating the location of the vortices in arrays by using current pulses, compatible with rapid single flux quantum technology. It is shown theoretically, using a modified resistively shunted junction model, that braiding operations can be achieved using current pulses injected from the edge of the array. It is necessary to use vortex sites with elevated critical current as traps.
Canted standing spin-wave modes of permalloy thin films observed by ferromagnetic resonance
Authors: Dąbrowski Maciej , Hicken Robert J , Frisk Andreas , Newman David G , Klewe Christoph , N’Diaye Alpha T , Shafer Padraic , van der Laan Gerrit , Hesjedal Thorsten , Bowden Graham J 
Published: January 2021

Abstract
Non-collinear spin structures in materials that combine perpendicular and in-plane magnetic anisotropies are of great technological interest for microwave and spin wave-assisted magnetization switching. [Co/Pt] multilayers are well-known perpendicular anisotropy materials that have the potential to pin the magnetization of a soft magnetic layer, such as permalloy (Py), that has in-plane anisotropy, thereby forming a magnetic exchange spring. Here we report on multilayered [Co/Pt]/Pt/Py films, where an additional ultrathin Pt spacer has been included to control the coupling between the sub-units with in-plane and perpendicular magnetic anisotropy. Vector network analyser (VNA)-ferromagnetic resonance (FMR) measurements were made to obtain a complete picture of the resonant conditions, while the dynamical response of the sub-units was probed by synchrotron-based element- and phase selective x-ray detected FMR (XFMR). For all samples, only slight pinning of the dynamic magnetization of the Py by the [Co/Pt] was noted, and the FMR results were dominated by the 50 nm thick Py layer. Out-of-plane VNA-FMR maps reveal the presence of additional modes, e.g. a perpendicular standing spin-wave (PSSW) state. However, as the magnetic field is reduced below the saturation field, the PSSW state morphs continuously through a series of canted standing spin-wave (CSSW) states into a horizontal standing spin-wave (HSSW) state. The PSSW, CSSW and HSSW states are well described using a multilayer model of the Py film. The observation of CSSW modes is of particular relevance to microwave assisted magnetic recording, where microwave excitation stimulates precession of a soft layer canted out of plane by a pulsed magnetic field.
Influence of local fields on the dynamics of four-wave mixing signals from 2D semiconductor systems
Authors: Hahn Thilo , Kasprzak Jacek , Machnikowski Paweł , Kuhn Tilmann , Wigger Daniel 
Published: January 2021

Abstract
In recent years the physics of two-dimensional semiconductors was revived by the discovery of the class of transition metal dichalcogenides. In these systems excitons dominate the optical response in the visible range and open many perspectives for nonlinear spectroscopy. To describe the coherence and polarization dynamics of excitons after ultrafast excitation in these systems, we employ the Bloch equation model of a two-level system extended by a local field describing the exciton–exciton interaction. We calculate four-wave mixing (FWM) signals and analyze the dependence of the temporal and spectral signals as a function of the delay between the exciting pulses. Exact analytical results obtained for the case of ultrafast (δ-shaped) pulses are compared to numerical solutions obtained for finite pulse durations. If two pulses are used to generate the nonlinear signal, characteristic spectral line splittings are restricted to short delays. When considering a three-pulse excitation the line splittings, induced by the local field effect, persist for long delays. All of the found features are instructively explained within the Bloch vector picture and we show how the exciton occupation dynamics govern the different FWM signals.
Thermodynamics of magnetic emergent crystals under coupled magnetoelastic fields
Authors: Hu Yangfan , Wan Xuejin , Wang Biao 
Published: January 2021

Abstract
Magnetic fields and mechanical forces can change the deformation and stability of magnetic emergent crystals (MECs) such as Bloch skyrmion crystal (SkX), Néel SkX and Anti-SkX. Due to the tensor nature of strains, mechanical loads provide more fruitful ways to manipulate the MECs, while their effect on MECs other than the Bloch SkX is hitherto unclear. We construct a thermodynamic model for noncentrosymmetric ferromagnets in all possible point groups when subjected to coupled magnetoelastic fields. Compared with classic theories, we include terms coupling the elastic strains, the magnetization, and its derivatives in the free energy, which lead to strain-induced Dzyaloshinskii–Moriya interaction anisotropy. For epitaxial thin films in three types of point groups (T, C
3v
, D
2d
) hosting Bloch SkX, Néel SkX and Anti-SkX, we find the newly added terms always deform the MECs and eventually lead to their instability as the misfit strains increase. Specifically, for Bloch SkX in group T materials and Néel SkX in group C
3v
materials, a novel magnetic phase called paired-skyrmion crystal (pSkX) appears. Our theory lays the path to study deformation and phase transitions of different MECs, and to explore novel states of MECs in chiral magnets when subjected to magnetoelastic fields.
A sparse multiscale nonlinear autoregressive model for seizure prediction
Authors: Yu Pen-Ning , Liu Charles Y , Heck Christianne N , Berger Theodore W , Song Dong 
Published: January 2021

Abstract

Objectives. Accurate seizure prediction is highly desirable for medical interventions such as responsive electrical stimulation. We aim to develop a classification model that can predict seizures by identifying preictal states, i.e. the precursor of a seizure, based on multi-channel intracranial electroencephalography (iEEG) signals. Approach. A two-level sparse multiscale classification model was developed to classify interictal and preictal states from iEEG data. In the first level, short time-scale linear dynamical features were extracted as autoregressive (AR) model coefficients; arbitrary (usually long) time-scale linear and nonlinear dynamical features were extracted as Laguerre–Volterra AR model coefficients; root-mean-square error of model prediction was used as a feature representing model unpredictability. In the second level, all features were fed into a sparse classifier to discriminate the iEEG data between interictal and preictal states. Main results. The two-level model can accurately classify seizure states using iEEG data recorded from ten canine and human subjects. Adding arbitrary (usually long) time-scale and nonlinear features significantly improves model performance compared with the conventional AR modeling approach. There is a high degree of variability in the types of features contributing to seizure prediction across different subjects. Significance. This study suggests that seizure generation may involve distinct linear/nonlinear dynamical processes caused by different underlying neurobiological mechanisms. It is necessary to build patient-specific classification models with a wide range of dynamical features.
Kinetic ballooning mode unstable in the 2nd stability regime as a possible source of the low-k broadband fluctuation observed in the wide-pedestal QH-mode
Authors: Kim J.Y. , Han H.S. 
Published: January 2021

Abstract
The kinetic ballooning mode destabilized by the ion magnetic curvature drift resonance in the 2nd ballooning stability regime is shown to be a plausible candidate for the low-k broadband fluctuation recently observed in the wide-pedestal quiescent-H (QH) mode of DIII-D. With its intrinsic real frequency approaching very closely to the ion pressure diamagnetic frequency in the pedestal-like condition with a steep gradient, this mode can be nearly free from the first-order ExB flow shear effect driven by the ion pressure gradient. As a result, it can be sensitive to the next-order one by toroidal rotation, with the possible strong excitation in the low toroidal rotation limit. The frequency in the lab frame and the peak wavenumber spectrum of the mode appear to be in the range similar to those of the observed low-k fluctuation.
Scaling of impurity fractions for divertor detachment in high-density high-power operation scenarios
Authors: Huber A. , Chankin A.V. 
Published: January 2021

Abstract
For future reactor designs and for planning of operational scenarios in the present and future machines, impurity fractions in the tokamak divertor plasma, c

Z
, is an essential input for predictive scalings of divertor detachment. A new quantitative scaling law for c

Z
, averaged over the scrape-off layer (SOL), required to attain detachment is developed for high power H-mode plasmas operated at high densities close to the density limit. It is based on a simple SOL radiation model which uses the combination of the empirical scaling laws for the H-mode power threshold and the separatrix density limit imposed by MHD instabilities. Additionally, it assumes, in agreement with experimental observations that the width of the power conducting layer outside of the separatrix scales approximately with the ion poloidal gyro-radius. The derived expression for c

Z
scales strongly with toroidal magnetic field, B, major radius R, the factor of access of the power flow through the separatrix over that required for the L–H transition, f
LH, and isotope mass A:

c

Z

∝

B

1.47

R

1.59

f

L
H

1.38

/

A

1.38

. Estimates of required impurity fractions for divertor detachment for an number of impurity species (N2, Ne and Ar) in future tokamak reactors ITER and DEMO are made in the paper.
Comparative Characteristics of Big Data Storage Formats
Authors: Belov Vladimir , Tatarintsev Andrey , Nikulchev Evgeny 
Published: January 2021

Abstract
One of the most important tasks of any platform for big data processing is the task of the storing data received. Different systems have different requirements for the storage formats of big data, which raises the problem of choosing the optimal data storage format to solve the current problem. This paper describes the five most popular formats for storing big data, presents an experimental evaluation of these formats and a methodology for choosing the format.
The two-stage classification based on 1-SVM and RF classifiers
Authors: Demidova Liliya , Klyueva Irina 
Published: January 2021

Abstract
The approach to the two-stage classification based on the 1-SVM classifier used as the main classifier and the RF classifier used as the auxiliary classifier has been considered. The proposed approach improves the quality of classification when using imbalanced datasets. The results of the comparative analysis of the proposed approach and the alternative approach to the two-stage classification, in which the binary SVM classifier is used as the main classifier, and the RF classifier as the auxiliary classifier, are presented.
Laboratory complex for studying the quality of materials using spectral analysis of signals
Authors: Khamitov R M , Kolchurina M A , Kolchurina I Y , Ponomareva K V , Silvestrov Y G 
Published: January 2021

Abstract
The article describes the process of development and testing of a laboratory complex for spectral analysis of measured data, which is based on a signal processing method based on measuring the frequency and amplitude of the signal (spectral method) with further evaluation using fast Fourier transform. The described laboratory complex consists of a spectrum analyzer connected to a personal computer with special software installed on it, a loudspeaker and a laser sensor. The paper substantiates the relevance of the development, due to the fairly wide use of spectral analysis methods in science, technology and production, the advantages of using a laboratory complex in comparison with analogues were shown. There is a description of the experiments to measure the speed of objects, control their location, vibration measurement. The procedure of verification and calibration is performed with the use of this complex, as well as the use of the system of automatic regulation and stabilization of production processes and the training of laboratory works for students of different directions of training in technical and economic specialties.
Ultrasonic testing of concrete hardening in pile foundations
Authors: Loseva E S , Potapov A I , Osokin A I 
Published: January 2021

Abstract
This article discusses the ultrasonic method for monitoring the strength of concrete in piles. Geotechnical conditions of the city territory are indicated. The conditions of hardening of the concrete mixture in the pile shaft and the normal conditions of hardening of concrete samples are described. A detailed description of the control technique is given. The dependence of the ultrasonic wave propagation velocity on the age of concrete in piles and concrete samples is established. Based on the results of the work, it was concluded that it is possible to control the strength of concrete in-situ.
Physical principles of work and basic features of Universal Software Radio Peripheral
Authors: Ryabov I V , Nikitin P V , Bazhenov R I , Melnikova A I , Gorokhova R I 
Published: January 2021

Abstract
The current stage in the development of info communication systems is characterized by an active search for a solution to the problem of signal processing in dynamically changing conditions. Growing requirements for bandwidth implemented in practice lead researchers to search for new solutions that can work under restrictions previously considered fundamental, such as a high level of intersymbol distortions [1]. There are many useful signal recognition techniques that use a statistical apparatus, an apparatus for predicting dynamic processes, and means combining the features of different principles. Ensuring the reception of signals transmitted over the meteor channel of a radio communication requires, in addition to modern analog-to-digital conversion devices, the ability to directly synthesize precision signals for heterodyning systems, correlation analysis and statistical processing of a signal-noise complex. Similar problems arise in more traditional applications, such as radar and radio navigation. The most preferred tools of the developer and designer in all cases are devices that implement the technology of software-defined radio (SDR). The article describes the physical principles of Universal Software Radio Peripheral operating using software-defined radio (SDR) technology. It shows the implementation of the technology of software-defined radio system according to the concept of USRP for various tasks, architecture and generalized structure.
Equipment and technology for wastewater post-treatment for returning it to production cycle
Authors: Levin E V , Balgynova A M , Kyzy Ardak M , Korotkov V G , Kolotvin A V , Voloshin E V , Dudorov V E , Arstanaliev E U , Kh Galieva L , Akhmadiyeva Z R , Tsyrkaeva E A 
Published: January 2021

Abstract
Given there is development of state-of-the art technologies in the field of water treatment and the demanding requirements for environmental control, as well as trends in the cost increase of chemicals and usage costs of primary resources, it deemed necessary to modernize the water treatment and water purification systems in such a way as: firstly, to minimize discharges as such; secondly, to increase the degree of use of circulating water; thirdly, using modern non-reagent cleaning technologies to minimize the consumption of necessary chemical agents, which has a complex effect – both in merely economic terms (procurement, transportation, storage, movement and control), and from a practical perspective – increasing the environmental safety of production, area release, etc.
A Revised Particle Swarm Optimization Model of Airplane Evacuations
Authors: Luo Yuandan 
Published: January 2021

Abstract
Aircraft accidents such as the Sukhoi Superjet 100 aircraft crash on May 5, 2019 at Sheremetyevo airport recently have drawn the public attention, requiring a safer evacuation plan and aircraft designs. In this paper, we conduct an evacuation model based on Particle Swarm Optimization (PSO) algorithm. Also, we learn from the PSO with emotion factor algorithm which shows that increasing the emotion raises the average velocity and decreases the repulsion force exerted by neighbour passengers. Our simulations also suggest that adding reaction time and blocking the exits increase the evacuation time significantly. In addition, we conduct simulations that incorporate passengers carrying luggage, according to the real-life scenarios, which has longer evacuation time.
Cyclic Modulation Spectrum Based Bearing Defect Recognition
Authors: Li Hui , Deng Sanpeng 
Published: January 2021

Abstract
A novel practical technique for bearing defect detection and recognition based on cyclic modulation spectrum (CMS) is presented. Cyclic modulation spectrum stands as a much faster method to detect periodic modulation feature and has a lower complexity. CMS has a very fast calculation speed, but it can provide similar results with spectral correlation density. This advantage enables the cyclic modulation spectrum to extract useful information from the noisy environment in rotating machine. The validity of this technique is exhibited on bearing defect vibration data from an industrial gearbox. The results show the advantage of cyclic modulation spectrum. CMS can correctly pick up the transient features from interference signals and can accurately recognize the rolling element bearing defect.
Functionalized zeolitic imidazolate framework-8 as a drug carrier for bioimaging
Authors: Han Xu , Wen Lili , Su Zhongmin , Shan Guogang 
Published: January 2021

Abstract
There has been a surging interest in the synthesis of multifunctional nano platform for drug delivery and bioimaging. ZIF-8 of the zeolitic imidazolate series is widely used in the biological field as the leader of metal-organic frameworks (MOFs). Herein, we processed ZIF-8 nanoparticles (ZIF-8 NPs) by pyrolysis with high temperature, while ensuring that it does not destroy itself. The strategy of calcination ZIF-8 NPs at 600? for 5 min has a higher loading rate for doxorubicin hydrochloride (DOX). Moreover, through bioimaging of ZIF-8@C in A549 lung cancer cell, the red fluorescence was produced, indicating that ZC-6005@DOX successfully entered the cancer cell.
Research development of polymer modified asphalt
Authors: Liu X , Wei X 
Published: January 2021

Abstract
Since the reform and opening up policy, modified asphalt has achieved a qualitative leap from nothing to being, from small to large, from less to more, and has made great contributions to road construction in China. The good quality of modified asphalt is directly related to the safety and service life of road. Based on the research of modified asphalt at home and abroad, this paper briefly introduces the classification of modified asphalt, and according to the types of polymer modifiers in modified asphalt, the research status and progress of modified asphalt are described. At the same time, the development direction and application prospect of modified asphalt are put forward.
Monometallic phosphide catalyst of Ni2P for Hydrogen production in acidic Solution
Authors: Li Jiao , Xu Chunyan , Li Xiao , Su Zhongmin 
Published: January 2021

Abstract
Nowadays, it is particularly important to develop efficient hydrogen evolution catalyst in the process of water electrolysis. In this paper, a monometallic phosphide (Ni2P@C) was synthesized through a simple one-step calcination and phosphorization process, which was a high efficient catalyst for hydrogen evolution reaction. Ni2P@C exhibits satisfactory activity with a low overpotential of 215 mV and small Tafel slope of 105 mV dec−1 at the current density of 10 mA cm−2. In addition, the catalyst displayed favorable stability for 16 h when current density maintained at 10 mA cm−2. This work provides reference for monometallic phosphates as catalyst for hydrogen evolution.
Enhanced Optical Antennas with Fractal Metasurface
Authors: Fan Yizhe 
Published: January 2021

Abstract
Plasmonic is now a quickly expanding area of research for its versatile in a lot of areas with its perfect ability of confining EM waves and trapping light. Periodic metallic structures are excellent to manipulate the properties of the SPPs by modifying the geometry of the pattern. In this project, we demonstrate a kind of fractal metasurface based on Sierpinsky Nanocarpet to simulate a higher absorption peak and electric field enhancement. We experimentally change the dimension level, size, thickness and separation distance in order to study the geometry dependency of the photosensor. Compared to several different fractal metasurface, the optimized structure proposes an approximately 30% enhancement in light absorption compared to a commom log38 Sierpinsky Nanocarpet structure.