bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effective waves for random three-dimensional particulate materials
Authors: Gower Artur L , Kristensson Gerhard 
Published: January 2021

Abstract
How do you take a reliable measurement of a material whose microstructure is random? When using wave scattering, the answer is often to take an ensemble average (average over time or space). By ensemble averaging we can calculate the average scattered wave and the effective wavenumber. To date, the literature has focused on calculating the effective wavenumber for a plate filled with particles. One clear unanswered question was how to extend this approach to a material of any geometry and for any source. For example, does the effective wavenumber depend on only the microstructure, or also on the material geometry? In this work, we demonstrate that the effective wavenumbers depend on only microstructure, though beyond the long wavelength limit there are multiple effective wavenumbers for one fixed incident frequency. We show how to calculate the average wave scattered from a random particulate material of any shape, and for broad frequency ranges. As an example, we show how to calculate the average wave scattered from a sphere filled with particles.
Multipoint connection by long-range density interaction and short-range distance rule
Authors: Gentile Francesco 
Published: January 2021

Abstract
The performance of a system is influenced by the way its elements are connected. Networks of cells with high clustering and short paths communicate more efficiently than random or periodic networks of the same size. While many algorithms exist for generating networks from distributions of points in a plane, most of them are based on the oversimplification that a system’s components form connections in proportion to the inverse of their distance. The Waxman algorithm, which is based on a similar assumption, represents the gold standard for those who want to model biological networks from the spatial layout of cells. This assumption, however, does not allow to reproduce accurately the complexity of physical or biological systems, where elements establish both short and long-range connections, the combination of the two resulting in non-trivial topological features, including small-world characteristics. Here, we present a wiring algorithm that connects elements of a system using the logical connective between two disjoint probabilities, one correlated to the inverse of their distance, as in Waxman, and one associated to the density of points in the neighborhood of the system’s element. The first probability regulates the development of links or edges among adjacent nodes, while the latter governs interactions between cluster centers, where the density of points is often higher. We demonstrate that, by varying the parameters of the model, one can obtain networks with wanted values of small-world-ness, ranging from ∼1 (random graphs) to ∼14 (small world networks).
A comparative study between GGA, WC-GGA, TB-mBJ and GGA + U approximations on magnetocaloric effect, electronic, optic and magnetic properties of BaMnS2 compound: DFT calculations and Monte Carlo simulations
Authors: Kadim G , Masrour R , Jabar A 
Published: January 2021

Abstract
The magnetocaloric effect, electronic, optical and magnetic properties of BaMnS2 are studied using the Wu-Cohen-Generalized Gradients Approximation (WC-GGA), GGA, Tran and Blaha modified Becke-Johnson potential (TB-mBJ) and GGA + U(U is the Hubbard potential) approximations and Monte Carlo simulations. BaMnS2 has an antiferromagnetic behavior and a semiconductor character with a narrow band gap follows the trend WC-GGA < GGA < mBJ < GGA + U. The GGA + U transformed and increased the nature of the band gap, causing an apparent change in physical properties. The difference energy calculated between the magnetic configurations confirms that the ground state antiferromagnetic (AFM) is more stable than the paramagnetic (PM) states. The total magnetization, susceptibility, specific heat and magnetic entropy and relative cooling power of this compound are studied. The maximum value of the magnetic entropy was obtained near the paramagnetic AFM- PM transition for (WC-GGA, GGA) and GGA + U equal to 38.31 J.kg−1.K−1 and 16.72 J.kg−1.K−1 respectively.
Cosmological solution through gravitational decoupling in Brans-Dicke gravity
Authors: Sharif M , Majid Amal 
Published: January 2021

Abstract
In this paper, we compute an anisotropic cosmological solution through a minimal geometric deformation on a non-static spherical spacetime in the framework of self-interacting Brans-Dicke theory. The transformation of the radial component decouples the field equations into two arrays such that the influence of the anisotropic source is limited to one set only. We use FLRW universe model to obtain a solution of the system governed by the isotropic matter source. For this purpose, power-law models of the scale factor as well as massive scalar field are assumed while isotropic pressure and density are related via barotropic equation of state. The decoupling function, appearing in the other set, is evaluated through the conservation equation of the anisotropic source. Finally, we investigate the physical behavior, viability and stability of the extended FLRW solution for different values of the equation of state parameter. It is concluded that the solution is viable and stable for the massless scalar field and the radiation dominated universe.
Control of self-sustained oscillatory behavior in the dynamics of generalized Bonhoeffer-van der Pol system: Effect of asymmetric parameter
Authors: SONNA Armel Viquit , YEMELE David 
Published: January 2021

Abstract
A generalized form of the autonomous Bonhoeffer-van der Pol (BVdP) system described by a second-order dynamical system with six independent parameters consistent with its optimal mathematical modeling, instead of three usually used, is investigated. Through its equivalent form, the generalized asymmetric van der Pol-Duffing (GAVdPD) system and the steady states of this system are derived. The analysis show that the system may exhibit one or three steady states when it is driven by an external constant impulse taken as a main control parameter. Domain ranges in which the system can function as well as monostable system as a bistable system are derived. In addition, by means of the theory of Hopf Bifurcation, it appears that there are large possibilities for the system to work as self-sustained oscillator, forced oscillator or other possibilities for which the system does not operate, indicating the richness of this generalized form of the BVdP system. Limit cycle solutions are derived at the neighboring of the Andronov-Hopf Bifurcation points even for large values of the asymmetric parameter. All these results are checked through numerical simulations. Applying these analytical investigations to the electronic circuit executing the dynamics of the basic BVdP system, two distinct working regimes are highlighted, depending on the magnitude of the capacitance with respect to a threshold value function of the characteristic parameters both of the self and of the nonlinear resistance. Through PSPICE simulations the accuracy of these analytical and numerical investigations have been confirmed.
Quasi-periodic Oscillation of Blazar PKS 1424–418 in γ-Ray Band
Authors: Yang Jianping , Cao Gang , Zhou Bing , Qin Longhua 
Published: January 2021

Abstract
We perform the quasi-periodic oscillation (QPO) analysis of blazar PKS 1424−418 in the γ-ray (0.1–300 GeV) band from 2009 May 12 to 2019 September 17 (MJD 54963−58743). Using the spectral domain methods, Bhatta & Dhital reported that this source has 353 days periodic flux oscillations in the γ-ray flux. Adopting time domain methods, we confirm the previous detection that a possible γ-ray QPO of ∼355 days with the high significance level. Combining two methods of time domain and spectral domain provides stronger evidence for the existence of the QPO. Especially, after the strongest flare, γ-ray light-curve exhibits stronger periodic significance compared with the whole observation period. Assuming that the QPO is come from the orbital motion in a supermassive binary black hole system, the mass of primary black hole for this source is estimate as M ∼ 3.5 × 108–5.5 × 109
M
⊙.
Production of super-heavy nuclei in cold fusion reactions
Authors: Denisov V. Yu. , Sedykh I. Yu. 
Published: January 2021

Abstract
A model for cold-fusion reactions related to the synthesis of super-heavy nuclei in collisions of heavy projectile-nuclei with a 208Pb target nucleus is discussed. In the framework of this model, the production of the compound nucleus by two paths, the di-nuclear system path and the fusion path, are taken into account simultaneously. The formation of the compound nucleus in the framework of the di-nuclear system is related to the transfer of nucleons from the light nucleus to the heavy one. The fusion path is linked to the sequential evolution of the nuclear shape from the system of contacting nuclei to the compound nucleus. It is shown that the compound nucleus is mainly formed by the fusion path in cold-fusion reactions. The landscape of the potential energy related to the fusion path is discussed in detail. This landscape for very heavy nucleus-nucleus systems has an intermediate state, which is linked to the formation of both the compound nucleus and the quasi-fission fragments. The decay of the intermediate state is taken into account in the calculation of the compound nucleus production cross sections and the quasi-fission cross sections. The values of the cold-fusion cross sections obtained in the model agree well with the experimental data.
Review of field characterization techniques for high intensity therapeutic ultrasound
Authors: Xing Guangzhen , Wilkens Volker , Yang Ping 
Published: January 2021

Abstract
High-intensity therapeutic ultrasound (HITU) is a minimally invasive and non-ionizing medical procedure used to combat cancers. Faithful characterization of HITU fields is fundamental to ensure patient safety and clinical efficiency. However, standardized quality assurance protocols have not yet been established for HITU, which is a prerequisite for the wide acceptance of HITU as a therapeutic modality. This review discusses the challenges in the acoustic output characterization of HITU and the solutions that have been proposed to overcome this issue. The purpose of this review is to discuss the state of art of the metrological techniques, and invoke new ideas to prompt further development of HITU usage and characterization techniques, to ensure the safe and effective usage of therapeutic ultrasound.
Outer midplane neutral density measurements and H-mode fueling studies in NSTX-U
Authors: Scotti F. , Stotler D.P. , Bell R.E. , LeBlanc B.P. , Sabbagh S.A. , Soukhanovskii V.A. , Umansky M.V. , Zweben S.J. 
Published: January 2021

Abstract
Neutral density profiles are measured on the outboard midplane of the National Spherical Torus Experiment Upgrade (NSTX-U) using a two dimensional camera (ENDD, edge neutral density diagnostic) filtered for deuterium Balmer α (D
α
) emission interpreted via simulations using the Monte Carlo neutral transport code DEGAS 2. Deuterium atomic densities n
D are calculated by inverting the line-integrated D
α
brightness and using local measurements of electron density n
e and temperature T
e to determine atomic rate coefficients. The assumptions used in the derivation of n
D from D
α
emissivity are validated using DEGAS 2 to estimate contributions to emissivity due to electron impact excitation and molecular processes. Experimental measurements and DEGAS 2 simulations are compared over a database of L- and H-mode discharges, showing good agreement in D
α
emissivity profiles. Residual disagreement between experiment and simulations is suggestive of the possible role of intermittent transport and uncertainties in the molecular data. DEGAS 2 simulations are further used to complement the ENDD diagnostic, extracting neutral (atomic and molecular) densities at locations where the ENDD measurement are not made or where the assumptions used in the ENDD analysis are not valid. Deuterium atomic densities and ionization profiles on the outer midplane are compared for L-mode and H-mode discharges in NSTX-U. One-way coupling of DEGAS 2 to UEDGE multi-fluid simulations constrained by experimental data is used to study edge fueling and neutral penetration in NSTX-U discharges.
Optimizing beam-ion confinement in ITER by adjusting the toroidal phase of the 3D magnetic fields applied for ELM control
Authors: Sanchis L. , Garcia-Munoz M. , Viezzer E. , Loarte A. , Li L. , Liu Y.Q. , Snicker A. , Chen L. , Zonca F. , Pinches S.D. , Zarzoso D. 
Published: January 2021

Abstract
The confinement of neutral beam injection (NBI) particles in the presence of n = 3 resonant magnetic perturbations (RMPs) in 15 MA ITER DT plasmas has been studied using full orbit ASCOT simulations. Realistic NBI distribution functions, and 3D wall and equilibria, including the plasma response to the externally applied 3D fields calculated with MARS-F, have been employed. The observed total fast-ion losses depend on the poloidal spectra of the applied n = 3 RMP as well as on the absolute toroidal phase of the applied perturbation with respect to the NBI birth distribution. The absolute toroidal phase of the RMP perturbation does not affect the ELM control capabilities, which makes it a key parameter in the confinement optimization. The physics mechanisms underlying the observed fast-ion losses induced by the applied 3D fields have been studied in terms of the variation of the particle canonical angular momentum (δP

ϕ
) induced by the applied 3D fields. The presented simulations indicate that the transport is located in an edge resonant transport layer as observed previously in ASDEX upgrade studies. Similarly, our results indicate that an overlapping of several linear and nonlinear resonances at the edge of the plasma might be responsible for the observed fast-ion losses. The results presented here may help to optimize the RMP configuration with respect to the NBI confinement in future ITER discharges.
Analysis of the fusion performance, beam–target neutrons and synergistic effects of JET’s high-performance pulses
Authors: Kirov K.K. , Belonohy E. , Challis C.D. , Eriksson J. , Frigione D. , Garzotti L. , Giacomelli L. , Hobirk J. , Kappatou A. , Keeling D. , King D. , Lerche E. , Lomas P.J. , Nocente M. , Reux C. , Rimini F.G. , Sips A.C.C. , Van Eester D. , Contributors JET 
Published: January 2021

Abstract
Achieving high neutron yields in today’s fusion research relies on high-power auxiliary heating in order to attain required core temperatures. This is usually achieved by means of high neutral beam (NB) and radio frequency (RF) power. Application of NB power is accompanied by production of fast beam ions and associated beam–target (BT) reactions. In standard JET operational conditions, deuterium (D) NBs are injected into D plasmas. The injected beams comprise D atoms at full, one-half and one-third injected energy. Typically, the full energy of the injected D beams is between 90 and 120 keV, providing 1.4–2.0 MW of heating, which is about half of the injected power. Half-energy D beams carry about one-third of the injected power and the rest of the power is carried by the third energy fraction of D beams. Under these conditions, thermal fusion reactions, i.e. those between plasma ions, and BT reactions are of the same order of magnitude. This study addresses important issues regarding the impact of density, central electron and ion temperatures and their ratio, T
i(0)/T
e(0), on fusion performance, measured by the total neutron yield and BT neutron counts. NB/RF synergistic effects are discussed as well. It is demonstrated that thermal fusion gain increases linearly with normalised plasma pressure, β
N, and confinement, B
t
τ. The BT neutrons are, however, more difficult to predict and this task in general requires numerical treatment. In this study, BT neutrons in JET’s best-performing baseline and hybrid pulses are analysed and the underlying dependencies discussed. Central fast ion densities are found to decrease with increased density and density peaking. This is attributed to poorer beam penetration at high density. The BT reactions however are unchanged and can even increase if operating at higher core temperatures. An increase in the central ion temperature and T
i(0)/T
e(0) ratio leads to higher total and BT reaction rates whilst simultaneously the ratio of the BT to total neutron decreases significantly. NB/RF synergistic effects are found to have a negligible impact on total neutron rate. This can be explained by the reduced beam penetration in high-density conditions leading to lower central fast ion density.
Broadband generation of rational-order optical vortices using a bilateral meta-grating
Authors: Huang Kun , Liu Hong , Teng Jinghua 
Published: January 2021

Abstract
Optical vortices usually carry integer orbital angular momentum (OAM) of light. Recently, optical vortices with rational-order OAMs have also been created continuously for entangling the super-position OAM states of monochromatic light in a single device. Here, we report the broadband generation of such rational-order optical vortex beams by using a bilateral meta-grating. The meta-grating contains two oblique gratings that encode two sign-opposite linear phase profiles in two symmetric sides, thus leading to phase dislocation along the symmetric axis. We reveal that the encoded phase profiles are valid in a range of wavelengths due to the broadband response of the meta-grating. The measured phase, intensity and tilting angles match perfectly with theoretical prediction, suggesting the bilateral meta-grating as a powerful device to create broadband and continuous OAM of light for various applications such as optical micro-manipulation, optical communication, quantum physics, and super-resolution imaging.
Analytic treatment of nonparaxial full-Poincaré fields: singularity structure and trapping properties
Authors: Gutiérrez–Cuevas Rodrigo , Alonso Miguel A 
Published: January 2021

Abstract
An analytic extension to the nonparaxial regime of the full-Poincaré (FP) beams is presented. Instead of the stereographic mapping used in the paraxial case, these FP fields are defined in terms of a mapping from the polarization Poincaré sphere onto the sphere of plane-wave directions. It is shown that multipolar fields with complex arguments can be used to implement this mapping and provide closed-form expressions. The three-dimensional polarization singularities of the resulting fields are studied with the help of auxiliary fields presenting vortices at points where the polarization is circular or linear. Finally, the Mie scattering and trapping properties of the FP fields are studied, both of which are greatly simplified by the choice of fields.
Physical mechanism of layer-dependent strong and weak coupling with electromagnetic wave in 2H-MoS2
Authors: Liang Lin , Song Jizhe , Han Mengtong , Ding Yong , Li Qiu , Wang Jingang 
Published: January 2021

Abstract
In this work, we use the first-principles calculation method to theoretically study the strong and weak coupling between the layer-dependent MoS2 and electromagnetic waves. Through the calculation of the electronic structure and the analysis and fitting of Van Hove singularity (VHS), the differences between the strong coupling and weak coupling mechanisms are discussed. The exponential law of electronic structure parameters with the number of layers is explained. Finally, combined with cavity quantum electrodynamics (QED), it is revealed that the physical mechanism of strong coupling and weak coupling is related to the transition dipole moment. Strong coupling is dominated by inter-band transitions and weak coupling is dominated by in-band transitions.
Preliminary study of an open-air water-contacting discharge for direct nitrogen fixation
Authors: SHU Zhan , WANG Chuanqi , HOSSAIN Insaf , CHEN Qiang , LI Wanlian , WANG Jinqi , LIU Pengfei , XIONG Qing 
Published: January 2021

Abstract
Efficient nitrogen fixation through a reactive plasma process attracts intense interest due to the environmental issues induced by the conventional Haber–Bosch method. In this work, we present a direct and simple fixation routine without any catalysts for nitrogen in open air using an atmospheric-pressure pin-to-solution plasma electrolytic system. Nitrate, nitrite, and ammonia as the nitrogen-derived chemicals in solution were analyzed as indicators under various discharge conditions to estimate the energy efficiency of this process. The results show that the nitrogen fixation process was much more efficient by the pin-positive discharge compared to the negative one. N chemicals preferred to be formed when the solution was of negative polarity. It was also found that, with the help of solution circulation, the energy efficiency was enhanced compared to that of static liquid. However, an inverse trend was observed with the increase of the discharge current. Further study by optical emission spectroscopy indicates the important roles of active

N

2

*

and water vapour and their derived species near the plasma–water interface in the fixation process.
Nonlinear evolution and secondary island formation of the double tearing mode in a hybrid simulation
Authors: MAO Aohua , WANG Zhibin , HE Xianglei , WANG Xiaogang 
Published: January 2021

Abstract
Double tearing modes (DTMs), induced by double current sheet configurations or two neighboring rational surfaces with the same safety factor in tokamaks, are widely observed in solar, space, and fusion plasmas. In this paper, the evolution of DTMs without a guide field is investigated numerically using a hybrid model (electron fluid + ion PIC). The overall evolution processes of DTMs are qualitatively consistent with previous works using other models. The particle dynamics during the evolution of DTMs is analyzed in detail. Behaviors of ions and electrons present different characteristics around the reconnection region which gives rise to Hall effects producing the out-of-plane quadrupole magnetic field. In the explosive reconnection process with interactions between two DTMs islands, the asymmetric drive and the thin current layer feature lead to the emergence of secondary magnetic islands which develop with the late evolution of the DTMs.
Towards understanding the brittle–ductile transition in the extreme manufacturing
Authors: Zhang Tao , Jiang Feng , Huang Hui , Lu Jing , Wu Yueqin , Jiang Zhengyi , Xu Xipeng 
Published: January 2021

Abstract
The brittle–ductile transition (BDT) widely exists in the manufacturing with extremely small deformation scale, thermally assisted machining, and high-speed machining. This paper reviews the BDT in extreme manufacturing. The factors affecting the BDT in extreme manufacturing are analyzed, including the deformation scale and deformation temperature induced brittle-to-ductile transition, and the reverse transition induced by grain size and strain rate. A discussion is arranged to explore the mechanisms of BDT and how to improve the machinability based on the BDT. It is proposed that the mutual transition between brittleness and ductility results from the competition between the occurrence of plastic deformation and the propagation of cracks. The brittleness or ductility of machined material should benefit a specific manufacturing process, which can be regulated by the deformation scale, deformation temperature and machining speed.