bluuebunny/crossref_metadata_2025 huggingface dataset:
Foundation for adaptive charging solutions: Optimised use of electric vehicle charging capacity
Authors: Simolin Toni , Rauma Kalle , Rautiainen Antti , Järventausta Pertti , Rehtanz Christian
Published: September 2021

As electric vehicles (EVs) are emerging, smart and adaptive charging algorithms have become necessary to ensure safe and efficient operation of the grid. In the scientific literature, most of the proposed charging control algorithms focus solely on EV usage‐related behaviour, while the charging characteristics of EVs are overlooked. Herein, realistic charging characteristics are illustrated and discussed. More notably, to overcome the issues caused by the non‐idealities in charging characteristics, a new adaptive charging characteristics expectation algorithm is proposed. The objective of this algorithm is to enable accurate estimation of the non‐ideal charging characteristics. This can be used to reallocate any unused charging capacity and to ensure that the intended total capacity is used effectively. The effectiveness of the proposed algorithm is demonstrated using hardware‐in‐the‐loop simulations with commercial EVs and real charging data. The results show that the proposed algorithm achieves an 88%–97% capacity usage rate, while the current benchmark solution achieves only 45%.
The intermediate neutron capture process
Authors: Goriely S. , Siess L. , Choplin A.
Published: September 2021

Context.Carbon-enhanced metal-poor (CEMP) r/s-stars show surface-abundance distributions characteristic of the so-called intermediate neutron capture process (i-process) of nucleosynthesis. We previously showed that the ingestion of protons in the convective helium-burning region of a low-mass low-metallicity star can explain the surface abundance distribution observed in CEMP r/s stars relatively well. Such an i-process requires detailed reaction network calculations involving hundreds of nuclei for which reaction rates have not yet been determined experimentally.

Aims.We investigate the nuclear physics uncertainties affecting the i-process during the asymptotic giant branch (AGB) phase of low-metallicity low-mass stars by propagating the theoretical uncertainties in the radiative neutron capture cross sections, as well as the13C(α,n)16O reaction rate, and estimating their impact on the surface-abundance distribution.

Methods.We used the STAREVOL code to follow the evolution of a 1M⊙[Fe/H] = − 2.5 model star during the proton ingestion event occurring at the beginning of the AGB phase. In the computation, we adopt a nuclear network of 1160 species coupled to the transport processes and different sets of radiative neutron capture cross sections consistently calculated with the TALYS reaction code.

Results.It is found that considering systematic uncertainties on the various nuclear ingredients affecting the radiative neutron capture rates, surface elemental abundances are typically predicted within ±0.4 dex. The 56 ≲ Z ≲ 59 region of the spectroscopically relevant heavy-s elements of Ba-La-Ce-Pr as well as the r-dominated Eu element remain relatively unaffected by nuclear uncertainties. In contrast, the inclusion of the direct capture contribution impacts the rates in the neutron-richA ≃ 45, 100, 160, and 200 regions, and the i-process production of theZ ≃ 45 and 65–70 elements. Uncertainties in the photon strength function also impact the overabundance factors by typically 0.2–0.4 dex. Nuclear level densities tend to affect abundance predictions mainly in theZ = 74 − 79 regions. The uncertainties associated with the neutron-producing reaction13C(α,n)16O and the unknownβ-decay rates are found to have a low impact on the overall surface enrichment.

Conclusions.The i-process nucleosynthesis during the early AGB phase of low-metallicity low-mass stars remains sensitive to nuclear uncertainties, substantially affecting theoretical predictions of still unknown radiative neutron capture cross sections. Improved descriptions of direct neutron capture based on shell model calculations or experimental constraints from (d, p) reactions could help to decrease the uncertainties in the estimated rates. Similarly, constraints on the photon strength functions and nuclear level densities, for example through the Oslo method, in the neutron-rich region ofA ≃ 100 and 160 would increase the predictive power of the present simulations.
CARMENES detection of the Ca II infrared triplet and possible evidence of He I in the atmosphere of WASP-76b
Authors: Casasayas-Barris N. , Orell-Miquel J. , Stangret M. , Nortmann L. , Yan F. , Oshagh M. , Palle E. , Sanz-Forcada J. , López-Puertas M. , Nagel E. , Luque R. , Morello G. , Snellen I. A. G. , Zechmeister M. , Quirrenbach A. , Caballero J. A. , Ribas I. , Reiners A. , Amado P. J. , Bergond G. , Czesla S. , Henning Th. , Khalafinejad S. , Molaverdikhani K. , Montes D. , Perger M. , Sánchez-López A. , Sedaghati E.
Published: September 2021

Ultra-hot Jupiters are highly irradiated gas giants with equilibrium temperatures typically higher than 2000 K. Atmospheric studies of these planets have shown that their transmission spectra are rich in metal lines, with some of these metals being ionised due to the extreme temperatures. Here, we use two transit observations of WASP-76b obtained with the CARMENES spectrograph to study the atmosphere of this planet using high-resolution transmission spectroscopy. Taking advantage of the two channels and the coverage of the red and near-infrared wavelength ranges by CARMENES, we focus our analysis on the study of the Ca II infrared triplet (IRT) at 8500 Å and the He I triplet at 10 830 Å. We present the discovery of the Ca II IRT at 7σ in the atmosphere of WASP-76b using the cross-correlation technique, which is consistent with previous detections of the Ca II H&K lines in the same planet, and with the atmospheric studies of other ultra-hot Jupiters reported to date. The low mass density of the planet, and our calculations of the XUV (X-ray and EUV) irradiation received by the exoplanet, show that this planet is a potential candidate to have a He I evaporating envelope and, therefore, we performed further investigations focussed on this aspect. The transmission spectrum around the He I triplet shows a broad and red-shifted absorption signal in both transit observations. However, due to the strong telluric contamination around the He I lines and the relatively low signal-to-noise ratio of the observations, we are not able to unambiguously conclude if the absorption is due to the presence of helium in the atmosphere of WASP-76b, and we consider the result to be only an upper limit. Finally, we revisit the transmission spectrum around other lines such as Na I, Li I, Hα, and K I. The upper limits reported here for these lines are consistent with previous studies.
A new method for global optimization
Authors: Kosolap Anatolii
Published: September 2021

This paper presents a new method for global optimization. We use exact quadratic regularization for the transformation of the multimodal problems to a problem of a maximum norm vector on a convex set. Quadratic regularization often allows you to convert a multimodal problem into a unimodal problem. For this, we use the shift of the feasible region along the bisector of the positive orthant. We use only local search (primal-dual interior point method) and a dichotomy method for search of a global extremum in the multimodal problems. The comparative numerical experiments have shown that this method is very efficient and promising.
Aromatherapie und Aromapflege als Teil der Integrativen
Gesundheitsversorgung
Authors: Hillert Gisela
Published: September 2021

Aromatherapie und Aromapflege, zusammengefasst unter dem Dachbegriff
Pflegetherapeutische Aromakultur (PTAK), sind mittlerweile vielfach gelebte
Realität im Palliativbereich und der ambulanten wie stationären
Altenpflege, seltener jedoch noch in der Klinik anzutreffen. Man versteht
hierunter die Anwendung naturreiner ätherischer und fetter
Pflanzenöle und Hydrolate (Pflanzenwässer) als
phytotherapeutische Behandlung und integrative Pflege sowie Maßnahmen
zur Geruchsverbesserung und Förderung des Wohlbefindens über die
Raumbeduftung. In diesem Beitrag soll neben Möglichkeiten und Nutzen der
PTAK gezeigt werden, wie eine Implementierung in das einrichtungsspezifische
Setting gelingen kann, und welche Faktoren es beim Qualitätsmanagement
und der interdisziplinären Zusammenarbeit der beteiligten Berufsgruppen
zu berücksichtigen gilt.
Stillen und Gewichtsentwicklung im Wochenbett – differenziert beurteilen und begleiten
Authors: Guóth-Gumberger Márta
Published: September 2021

Den Stillbeginn zu begleiten, ist eine essenzielle Aufgabe der Hebamme und hat einen prägenden Einfluss auf die gesamte weitere Stillzeit. Besonders wichtig ist ihre Unterstützung in Fällen, in denen sich das Gewicht des Säuglings nicht optimal entwickelt. Dieser Artikel bietet die notwendigen Informationen, die es Hebammen ermöglicht, die normalen Anlaufschwierigkeiten von den Situationen zu unterscheiden, die intensivere Begleitung, Ursachensuche und unterstützende Maßnahmen erfordern.
Synthesis of Unsymmetrically Functionalized Violanthrenes by Reductive Aromatization of Violanthrone 79
Authors: Sundermeyer Jörg , Werner Simon
Published: September 2021

The commercially available n-type semiconductive dye Violanthrone 79 was used as starting material to synthesize previously unexplored substituted violanthrenes through a reductive aromatization and functionalization strategy. By using the low-cost reducing agents zinc and sodium dithionite in combination with suitable electrophilic trapping reagents, three violanthrenes functionalized with two pivalyloxy, trimethylsiloxy, or methoxy groups were selectively obtained in high yields. Due to their octyl ether moieties, these new red dyes are highly soluble. They were characterized by means of UV/vis and fluorescence spectroscopy, and their redox properties were studied by cyclic voltammetry. The spectroscopically determined frontier molecular orbital energies are compared to those calculated by density functional theory and suggest that electron-deficient Violanthrone 79 was transformed into three electron-rich violanthrenes with molecular characteristics typically observed in molecular precursors for p-type organic semiconductors.
A Straightforward, Purification-Free Procedure for the Synthesis of Ando and Still–Gennari Type Phosphonates
Authors: Janicki Ignacy , Kiełbasiński Piotr
Published: September 2021

Z-Selective Still–Gennari and Ando modifications of the typically E-selective Horner–Wadsworth–Emmons reaction are highly valuable synthetic tools in organic chemistry. These procedures are based on application of bis(2,2,2-trifluoroethyl) phosphonates or diaryl phosphonates, respectively, for the olefination of carbonyl groups. In our research, we present an improved, straightforward, purification-free procedure for the synthesis of these reagents. The key step of our procedure is the reaction of phosphonic dichlorides with the appropriate sodium alkoxides, which results in 52–97% isolated yields of the desired products on a gram scale. The whole three-step process is performed in one pot. Most importantly, the product is obtained in over 95% purity after simple extraction, avoiding column chromatography and distillation. Moreover, we present the synthesis of a novel Still–Gennari type reagent, bis(1,1,1,3,3,3-hexafluoroisopropyl) phosphonates, which may exhibit improved Z-selectivity in Still–Gennari olefinations.
Clifford quantum cellular automata: Trivial group in 2D and Witt group in 3D
Authors: Haah Jeongwan
Published: September 2021

We study locality preserving automorphisms of operator algebras on D-dimensional uniform lattices of prime p-dimensional qudits quantum cellular automata (QCAs), specializing in those that are translation invariant (TI), and map every prime p-dimensional Pauli matrix to a tensor product of Pauli matrices (Clifford). We associate antihermitian forms of the unit determinant over Laurent polynomial rings to TI Clifford QCA with lattice boundaries and prove that the form determines the QCA up to Clifford circuits and shifts (trivial). It follows that every 2D TI Clifford QCA is trivial since the antihermitian form in this case is always trivial. Furthermore, we prove that for any D, the fourth power of any TI Clifford QCA is trivial. We present explicit examples of nontrivial TI Clifford QCA for D = 3 and any odd prime p and show that the Witt group of the finite field Fp is a subgroup of the group C(D=3,p) of all TI Clifford QCA modulo trivial ones. That is, C(D=3,p≡1mod4)⊇Z2×Z2 and C(D=3,p≡3mod4)⊇Z4. The examples are found by disentangling the ground state of a commuting Pauli Hamiltonian, which is constructed by coupling layers of prime dimensional toric codes such that an exposed surface has an anomalous topological order that is not realizable by commuting Pauli Hamiltonians strictly in two dimensions. In an appendix independent of the main body of this paper, we revisit a recent theorem of Freedman and Hastings that any two-dimensional QCA, which is not necessarily Clifford or translation invariant, is a constant depth quantum circuit followed by a shift. We give a more direct proof of the theorem without using any ancillas.
Approximate tensor decompositions: Disappearance of many separations
Authors: De las Cuevas Gemma , Klingler Andreas , Netzer Tim
Published: September 2021

It is well known that tensor decompositions show separations, that is, constraints on local terms (such as positivity) may entail an arbitrarily high cost in their representation. Here, we show that many of these separations disappear in the approximate case. Specifically, for every approximation error ɛ and norm, we define the approximate rank as the minimum rank of an element in the ɛ-ball with respect to that norm. For positive semidefinite matrices, we show that the separations between rank, purification rank, and separable rank disappear for a large class of Schatten p-norms. For non-negative tensors, we show that the separations between rank, positive semidefinite rank, and non-negative rank disappear for all ℓp-norms with p > 1. For the trace norm (p = 1), we obtain upper bounds that depend on the ambient dimension. We also provide a deterministic algorithm to obtain the approximate decomposition attaining our bounds. Our main tool is an approximate version of the Carathéodory theorem. Our results imply that many separations are not robust under small perturbations of the tensor, with implications in quantum many-body systems and communication complexity.
Temperature response for active thermography using laser scanning heating and method of images
Authors: Hoshimiya Tsutomu , Endoh Haruo
Published: September 2021

When scanning a specimen using a line heat source at a constant velocity, a temperature change occurs partly due to specular reflection at the defect interface. Assuming that the reflection of a transient thermal response is similar to that of geometrical optics, we performed waveform analysis using an imaging method. Image points are calculated based on differential geometry; this can also be performed for a curved surface using a general equation. A combination of the steepest descent analysis of a moving heat source problem and a convolution technique successfully yielded waveforms comparable to those of experimental temperature responses. We designed and constructed an active thermographic imaging system in which a linearly focused continuous wave laser beam was scanned perpendicular to the beam as it covered the entire surface of specimens with simulated internal defects. The real-time response was recorded as a temperature waveform at each image pixel. Waveforms were calculated for specimens without or with buried cylindrical defects parallel to their surfaces and compared to the experimental data. The theory well-explains the signal generation mechanism, and excellent agreement was obtained in waveforms. Some discrepancy between theory and experiment indicates more complicated problems in heat and mass transfer.
Measurement of magnetic field distribution produced by high-current pulse using Zeeman splitting of Na emission distributed by laser ablation
Authors: Jiang Zhiyuan , Wu Jian , Zhang Daoyuan , Chen Ziwei , Wang Zhenyu , Shi Huantong , Li Xingwen , Qiu Aici
Published: September 2021

Measurement of the magnetic field distribution in Z-pinch experiments remains an ongoing challenge. We present a method of measuring the radial distribution of the magnetic field around a copper rod using Zeeman splitting of sodium (Na) emission lines, in which an Na layer is formed by the laser ablation of NaCl crystals on a load surface. The load consists of a copper rod of 2 mm diameter and is pre-covered on its surface by the NaCl crystals. An 8 ns pulsed laser with an energy of 1 J and wavelength of 532 nm is focused on the crystals. The Na plasma is produced and expands from the surface of the copper rod into a vacuum. After applying a pulsed current with a peak value of 375 kA to the load, the Na 3s–3p doublet displays significant Zeeman splitting patterns. The self-luminosity of the Na plasma is recorded by a spectrometer coupled with an intensified charge-coupled device camera from an end-on view to eliminate the effects of different observing angles and Doppler shifts. We determine the magnetic field by fitting the measured spectra with the calculated results of the Voigt profile. The measurable range of radial position is 5–7 mm, and the corresponding magnetic field is 5–15 T. The averaged error of curve fitting is less than 12%.
The α → 1 limit of the sharp quantum Rényi divergence
Authors: Bergh Bjarne , Salzmann Robert , Datta Nilanjana
Published: September 2021

Fawzi and Fawzi [Quantum 5, 387 (2021)] recently defined the sharp Rényi divergence, Dα#, for α ∈ (1, ∞), as an additional quantum Rényi divergence with nice mathematical properties and applications in quantum channel discrimination and quantum communication. One of their open questions was the limit α → 1 of this divergence. By finding a new expression of the sharp divergence in terms of a minimization of the geometric Rényi divergence, we show that this limit is equal to the Belavkin–Staszewski relative entropy. Analogous minimizations of arbitrary generalized divergences lead to a new family of generalized divergences that we call kringel divergences for which we prove various properties, including the data-processing inequality.
Impact and trends in embedding field programmable gate arrays and microcontrollers in scientific instrumentation
Authors: Carminati M. , Scandurra G.
Published: September 2021

Microcontrollers and field-programmable gate arrays have been largely leveraged in scientific instrumentation since decades. Recent advancements in the performance of these programmable digital devices, with hundreds of I/O pins, up to millions of logic cells, >10 Gb/s connectivity, and hundreds of MHz multiple clocks, have been accelerating this trend, extending the range of functions. The diversification of devices from very low-cost 8-bit microcontrollers up to 32-bit ARM-based ones and a system of chip combining programmable logic with processors make them ubiquitous in modern electronic systems, addressing diverse challenges from ultra-low power operation, with sub-µA quiescent current in sleep mode for portable and Internet of Things applications, to high-performance computing, such as in machine vision. In this Review, the main motivations (compactness, re-configurability, parallelization, low latency for sub-ns timing, and real-time control), the possible approaches of the adoption of embedded devices, and the achievable performances are discussed. Relevant examples of applications in opto-electronics, physics experiments, impedance, vibration, and temperature sensing from the recent literature are also reviewed. From this bird-eye view, key paradigms emerge, such as the blurring of boundaries between digital platforms and the pervasiveness of machine learning algorithms, significantly fostered by the possibility to be run in embedded devices for distributing intelligence in the environment.
Improved one-dimensional “piston” model of electrohydraulic shock wave based on discharge current interception
Authors: Liu Yi , Ren Yi-Jia , Liu Si-Wei , Li Hua , Lin Fu-Chang , Zhao Yong
Published: September 2021

Based on the pulsed current interception of underwater discharge, the characteristics of the steepness of electrohydraulic shock waves (EHSWs) and the peak value still increasing slowly with the electrical energy injection after the acceleration expansion phase of the plasma channel are investigated. The one-dimensional “piston” model of the EHSW generation is improved, and the calculation method for the EHSWs based on the “piston” model is modified. The modified model takes the change of starting points and the rising steepness of EHSWs into account, and the rising edge and peak value of EHSWs can be calculated more precisely.
Existence of the first magic angle for the chiral model of bilayer graphene
Authors: Watson Alexander B. , Luskin Mitchell
Published: September 2021

We consider the chiral model of twisted bilayer graphene introduced by Tarnopolsky, Kruchkov, and Vishwanath (TKV). TKV proved that for inverse twist angles α such that the effective Fermi velocity at the moiré K point vanishes, the chiral model has a perfectly flat band at zero energy over the whole Brillouin zone. By a formal expansion, TKV found that the Fermi velocity vanishes at α ≈ 0.586. In this work, we give a proof that the Fermi velocity vanishes for at least one α between 0.57 and 0.61 by rigorously justifying TKV’s formal expansion of the Fermi velocity over a sufficiently large interval of α values. The idea of the proof is to project the TKV Hamiltonian onto a finite-dimensional subspace and then expand the Fermi velocity in terms of explicitly computable linear combinations of modes in the subspace while controlling the error. The proof relies on two propositions whose proofs are computer-assisted, i.e., numerical computation together with worst-case estimates on the accumulation of round-off error, which show that round-off error cannot possibly change the conclusion of computation. The propositions give a bound below on the spectral gap of the projected Hamiltonian, an Hermitian 80 × 80 matrix whose spectrum is symmetric about 0, and verify that two real 18-th order polynomials, which approximate the numerator of the Fermi velocity, take values with a definite sign when evaluated at specific values of α. Together with TKV’s work, our result proves the existence of at least one perfectly flat band of the chiral model.
Images of point charges in conducting ellipses and prolate spheroids
Authors: Majic Matt
Published: September 2021

This is an investigation into the exact forms of images of point charges in 2D conducting ellipses and 3D prolate spheroids. For an ellipse with an exterior point source, we compare two previous expressions for the analytic continuation inside the ellipse down to the focal line, the location of the image charge. For an interior source, we discover a sequence of image charges lying outside. For a point source close to the surface of a spheroid, series solutions for the potential diverge in a region that encompasses the singularities of the continuation of the reflected potential inside the spheroid. We uncover an image system for a point charge on the axis of a prolate spheroid that extends from the focal segment somewhat further up the axis. For an off-axis charge, we find a new approximate image charge. For a point charge at the center of the spheroid, the image singularity is found to lie on an infinitely wide, flat sheet with a hole around the spheroid. For a point charge located anywhere inside the spheroid, we find two new approximate image charge solutions: a point charge in real space, which applies when the source lies near the surface, or a point charge in complex space that projects as a ring in the real space which applies when the source lies near the rotation axis. When the point charge lies exactly on a focal point, a multipole of order 1/2 is an ideal image approximation.
Exact models of pure radiation in R2 gravity for spatially homogeneous wave-like Shapovalov spacetimes type II
Authors: Osetrin Konstantin , Osetrin Evgeny , Filippov Altair
Published: September 2021

Presented are exactly integrable models with pure radiation in R2 gravity with a cosmological constant related to wave-like Shapovalov spacetimes type II. Spatially homogeneous models of Shapovalov spacetimes were considered. The obtained solutions belong to spaces of type III according to the Bianchi classification and of type N according to the Petrov classification. For the models under consideration, exact solutions for the equations of motion of test particles are obtained in the Hamilton–Jacobi formalism. For the obtained exact models, solutions of the geodesic deviation equations are obtained.
Enhancement of Curie temperature and reorientation of spin in doped Cr2Si2Te6
Authors: Liu Xiao , Wang Zhong-Yi , Liu Da-Yong , Zou Liang-Jian
Published: September 2021

In this paper, we present the electronic and magnetic properties of the ferromagnetic semiconductor Cr2Si2Te6 doped by charge particles by the first-principles calculations. We find that doped Cr2Si2Te6 manifests a ferromagnetic metallic phase and its Curie temperature significantly increases from 54 to 125 K, as well as the magnetic coupling changing from weak super-exchange to strong double-exchange interaction. Moreover, the magnetic easy axis in doped Cr2Si2Te6 rotates from the ⟨001⟩ direction to the ab-plane. Our results provide an easily accessible method to considerably increase the ferromagnetic transition temperature of van der Waals crystals.
Electrochemical performance of a new all solid-state ultra-low noise electrospray electrode as a marine electric field sensor
Authors: Xin Yi , Liu Chenyang , Cui Meng , Hou Tianyuan , Liu Houyan , Tong Junye , Lin Tingting , Liu Changsheng , Yang Dapeng
Published: September 2021

A new type of Ag/AgCl electrode as a marine electric field sensor is prepared using electrospray. The surface of the electrode is porous, and the particle size of AgCl is small and uniform with an average particle size of 1.43 µm, which accelerated the speed of the oxidation–reduction reactions. Therefore, the electrode with large specific surface area has high stability and low noise. The impedance, sensitivity, self-noise, and stability of the electrode are measured to study the electrochemical performance of the electrode. The impedance of the electrode is 7.9 Ω, and the electrode shows resistance characteristics, meaning that the electrode can well receive the weak ocean electric field signals with low signal distortion. The sensitivity experiment result shows that the electrode can well restore the sinusoidal electric field signal of 1 Hz (10 mV). The voltage drift is less than 5 µV/100 h, the self-potential is between −51 and 56 µV, and the self-noise of the electrode is 2.48 nV @ 1 Hz. The AgCl layer on the surface of the electrode is porous and thick, and the particle size of AgCl is small and uniform. This makes the electrode have excellent electrochemical performance. All the experimental results show that the electrode has ultra-low noise and excellent response to low frequency weak electric field signals. The electrode is of great significance to the exploitation of marine resources as the marine electric field sensor.
First-principles magnetic treatment of the uranium nitride (100) surface and effect on corrosion initiation
Authors: Sikorski Ember L. , Jaques Brian J. , Li Lan
Published: September 2021

The magnetic properties of uranium nitride (UN) surfaces are not well understood experimentally or computationally but they have a significant effect on UN performance as a nuclear fuel. We investigated ferromagnetic (FM), antiferromagnetic (AFM), nonmagnetic (NM), and three hybrid magnetic structures of the most stable UN surface (100). To account for electron correlation and metastability, a U-ramp was performed to an effective Hubbard U-term of 2.0 eV. FM was found to be the most energetically favorable magnetic structure. Type 1 AFM slab was optimized to a new magnetic structure consisting of (100) planes with either all spin-up electrons, all spin-down electrons, or half spin-up and half spin-down electrons on uranium atoms. After OH adsorption to simulate corrosion initiation, the AFM, FM, and NM structures yield relatively similar bond lengths but varying bond angles, adsorption energies, and electronic profiles. Partial charge density maps show varying degradation mechanisms across magnetic structures. Electron localization function reveals more charge localized to AFM uranium atoms with spin-down electrons than uranium atoms with spin-up electrons. This leads to different properties depending on if an adsorbate interacts with a spin-up or spin-down terminated AFM surface. This work supports the physical accuracy of future computational studies toward corroborating with experiments and addressing UN fuel corrosion.
New instrument based on electrostatic sensor array for measuring tribo-electrification charging due to single particle impacts
Authors: Guo Jiachen , Zuo Hongfu , Zhong Zhirong , Jiang Heng
Published: September 2021

In the processing of particulate solids, particle–particle and particle-wall collisions can generate electrostatics. This is called contact/impact/frictional electrification and can lead to many problems such as affecting powder flow and explosion hazards. It is necessary to research the tribo-electrification charging due to single particle impacts on a target as the fundamental understanding of tribo-electrification. A new impact charging test rig based on an electrostatic sensor array that can measure charge transfer caused by a single impact between a particle and a target plane has been designed and established. Combined with the electrostatic sensor array, the compressed sensing algorithm is used to estimate not only the spatial position but also the charge amount of particle. The cross-correlation algorithm is used to determine particle’s velocity instead of using other devices such as a photodetector. The new instrument allows single particles impacting target planes at different angles with a velocity exceeding 100 m/s. An oil calibration test rig has been constructed to verify the proposed methods. The estimation errors of the spatial position and charge amount are both within 5% when the particle is located at the central area of the pipeline and the estimation errors of velocities are within 2%. The impact charging experiments show a special initial charge prior to impact for which no net charge transfer would occur for polymer particles, but the charge would completely transfer for metal particles.
Phase transition filter from controllable hybrid line shape of correlation and squeezing of Pr3+: YPO4 and Eu3+: YPO4
Authors: Ullah Habib , Li Jinyang , Mujahid Anas , Li Yufeng , Wang Yafen , Ahmed Irfan , Zhang Yanpeng
Published: September 2021

We report the symmetry-dependent intensity–noise correlation and the intensity-difference squeezing of spontaneous parametric four-wave mixing (SP-FWM) and fluorescence (FL) hybrid signals from the different phases [hexagonal (H) + tetragonal (T), T + H] of Pr3+: YPO4 and Eu3+: YPO4 crystals. The competition between FL and SP-FWM in hybrid signals determines the amplitude and hybrid line shape of the two-mode and three-mode correlation. The correlation amplitude switches from positive to negative due to strong double dressing caused by a high transition probability and a dipole moment of the (more H + less T)-phase of Pr3+: YPO4. This switching phenomenon is used to realize a metal–oxide semiconductor field-effect transistor-based logic inverter. Furthermore, the line shape of correlation changes from broad to sharp due to weak dressing, transition probability, and a low dipole moment of the (more T + less H)-phase of Pr3+: YPO4. Based on these results, we proposed the model of a tunable correlation filter. Gate position, frequency detuning, and laser power control the amplitude and hybrid line shape. Our experimental results provide an advanced technique of bandwidth contrast of about 0.9%. Such notch filters have potential applications in quantum communications.
Room temperature magnetoelectric coupling in Pb(Fe1/2Nb1/2)O3 by counterbalancing imbalanced spin moments through spin canting
Authors: Cho Jae-Hyeon , Lee Ju-Hyeon , Jang Haeseong , Lee Nyun Jong , Kang Woo-Seok , Hwang Geon-Tae , Kim Sanghoon , Kim Min Gyu , Jo Wook
Published: September 2021

In this study, ferroelectric Pb(Fe1/2Nb1/2)O3 with an antiferromagnetic polymorph at and below 150 K was converted into a room-temperature magnetoelectrically active multiferroic with soft ferromagnetism by disrupting the existing antiparallel spin alignment of Fe ions through the heavy replacement of Fe by Ni. To maximize the induced soft-ferromagnetic properties and the consequent nonlinear magnetoelectric coupling, the substitution level of Ni should be controlled such that the individual Ni ions are separated from one another to avoid mutual spin cancellation. The induced magnetoelectric coupling was found to originate from the collective contribution of oppositely canted pairs of spins in two nearby Fe3+ ions, which counterbalances the relatively smaller spin moment of the in-between Ni ions. The non-material specific nature of this strategy implies that it can be used in the development of new room-temperature multiferroic perovskite oxides.
Hyperbolic plasmon–phonon dispersion and tunable spontaneous emission enhancement in Ge2Sb2Te5-based multilayer graphene and hBN system
Authors: Zhou Kun , Lu Lu , Li Bowen , Cheng Qiang
Published: September 2021

Active tunability of phonon dispersion and spontaneous emission (SE) still remain open owing to its exciting application potential. In this study, multilayer graphene and hexagonal boron nitride (hBN) combined with the Ge2Sb2Te5 (GST) functional substrate are proposed to obtain tunable hyperbolic plasmon–phonon dispersion and SE. Results indicate that GST phase change has a profound impact on hyperbolic phonon polaritons in the hBN layer and can obtain an actively tunable SE. Moreover, when graphene is introduced into the hBN/GST system, hyperbolic plasmon–phonon polaritons inside the two reststrahlen (RS) bands of hBN and surface plasmon–phonon polaritons outside the two RS bands can be achieved, both of which can be actively tuned by adjusting the GST phase state and graphene chemical potential. In addition, the coupled polariton branches between hBN phonon polaritons and graphene plasmons become stronger and corresponding SE enhancement regions obviously broaden with increasing the graphene/hBN layer numbers for the fixed thickness multilayer graphene/hBN on GST substrate. These characteristics may provide an available route to realize active tunability of both phonon dispersion and SE enhancement of natural or artificial hyperbolic materials.
Supersymmetric quantum mechanics and coherent states for a deformed oscillator with position-dependent effective mass
Authors: da Costa Bruno G. , da Silva Genilson A. C. , Gomez Ignacio S.
Published: September 2021

We study the classical and quantum oscillator in the context of a non-additive (deformed) displacement operator associated with a position-dependent effective mass by means of the supersymmetric formalism. From the supersymmetric partner Hamiltonians and the shape invariance technique, we obtain the eigenstates and the eigenvalues along with the ladders operators, thus showing a preservation of the supersymmetric structure in terms of the deformed counterpartners. The deformed space in supersymmetry allows to characterize position-dependent effective mass and uniform field interactions and to obtain a generalized uncertainty relation (GUP) that behaves as a distinguishability measure for the coherent states, these latter satisfying a periodic evolution for the corrections of the GUP.
Suppressing the interlayer-gliding of layered P3-type K0.5Mn0.7Co0.2Fe0.1O2 cathode materials on electrochemical potassium-ion storage
Authors: Zhong Wentao , Liu Xiaozhao , Cheng Qian , Tan Ting , Huang Qianhui , Deng Qiang , Hu Junhua , Yang Chenghao
Published: September 2021

In recent years, potassium-ion batteries (KIBs) have emerged as a promising alternative candidate to replace lithium-ion batteries for large-scale energy storage devices owing to the natural abundance of potassium and similar mechanism as lithium-ion batteries. In particular, transition metal oxide cathode materials have attracted growing attention due to their high theoretical capacities and low cost compared with other cathode materials. Nevertheless, due to the larger ionic radius of K-ions, transition metal oxide cathode materials suffer from irreversible structural evolution and interlayer-gliding of transition metal layers in potassiation/depotassiation, which results in sluggish kinetics and structural instability. This limited capacity and unsatisfactory cycling properties inhibit the practical application of potassium-ion batteries. It still remains a challenge to develop the suitable cathode materials for potassium-ion batteries. In this work, the interlayer-gliding and irreversible P3–O3 structure transition were suppressed via the replacement of cobalt and iron, and the doping mechanism was investigated by in situ x-ray diffraction. The incorporation of Co ions and Fe ions enlarges the d-space between the transition metal layers, reduces the resistance of K+ migration, and provides the buffer spaces to suppress the interlayer-gliding and P3–O3 phase transformation in electrochemical potassium-ion storage, leading to an enhanced rate capability (58 mA h g−1 at 1 A g−1) and superior cycling stability (71% after 300 cycles at 200 mA g−1). This strategy provides a better understanding for the effect of Co–Fe substitution in suppressing interlayer-gliding and improving electrochemical properties for the development of a novel cathode material for potassium-ion batteries.
Ion core effect on scattering processes in dense plasmas
Authors: Ramazanov T. S. , Kodanova S. K. , Nurusheva M. M. , Issanova M. K.
Published: September 2021

A pseudopotential approach was used to study the effect of an ionic core on the electron–ion scattering in dense plasmas. Screening of the ion charge is taken into account using the density response function in the long wavelength limit. Additionally, the effect of electronic non-ideality is included using the compressibilty sum-rule connecting the local field correction and the exchange-correlation part of the electronic free energy density. Using a screened pseudopotential, we have computed electron–ion scattering phase shifts, the total elastic scattering cross section, and the transport cross section. It is found that the ionic core leads to the strong decrease in the scattering cross sections. Additionally, it is shown that the transport cross section has a non-monotonic dependence on the variation of the ionic core field parameters.
Study of pressure-swirl atomizer with spiral path at design point and outside of design point
Authors: Khani Aminjan Kiumars , Heidari Milad , Ganji D. D. , Aliakbari Maryam , Salehi Fatemeh , Ghodrat Maryam
Published: September 2021

Studies on pressure-swirl atomizers have mainly focused on pressure-swirl atomizers with tangential input while there are limited studies on pressure-swirl atomizers with a spiral path. This study applies experimental and computational methods to provide a better understanding of flow development in this type of atomizer at the design point and outside the design point. Experimental results showed that as the pressure increases, the spray cone angle increases. This increase initially occurs with a higher slope and then the slope is toned down. While the drainage coefficient remains constant, the droplet diameter decreases as the pressure increases. It is observed that similar to the pressure-swirl atomizer with tangential input, the pressure-swirl atomizer with a spiral path has a conical hollow spray. At the constant mass flow rate, as the spiral path cross-section, the length of the swirl chamber and orifice diameter increase, the fluid film thickness and average diameter of droplets increase while the spray cone angle reduces. Further, increasing the number of spiral paths causes a wider spray cone angle, higher discharge coefficient, larger fluid film thickness, and larger droplet diameter. The results also showed that increasing the length of the orifice marginally affected the properties of the spray while significantly reducing the spray cone angle. It is important to note that the numerical results are in good agreement with the experimental data.
Eliminating spurious currents in phase-field-theory-based lattice Boltzmann equation for two-phase flows
Authors: Zheng Lin , Zheng Song , Zhai Qinglan
Published: September 2021

Spurious currents are frequently observed near an interface in the equilibrium multiphase flow system by lattice Boltzmann equation (LBE). These unphysical phenomena are the result of force imbalance of LBE at a discrete level. In this paper, we develop a well-balanced Cahn–Hilliard equation-based LBE for incompressible two-phase flows. The effects of small initial perturbation of order parameter or dynamic pressure and nonisotropic discretization of gradient in force term on eliminating the spurious currents are investigated systematically. Numerical simulations including flat interface and stationary droplet problems are carried out to show the capability of present LBE for eliminating the spurious currents and its accuracy. The results predicted by the present LBE are compared with those by mixed isotropic discretizations scheme (MIDS) frequently used in the LBE community. Numerical results show that the initial perturbation of order parameter or dynamic pressure and nonisotropic discretization of gradient term has no significant effect on eliminating the spurious currents by present LBE, while the MIDS is sensitive to them.
Experimental observation of flow-induced vibrations of a transversely oscillating D-section prism
Authors: Chen Weilin , Zhao Yawei , Ji Chunning , Srinil Narakorn , Song Liqun
Published: September 2021

Fluid–structure interactions of non-circular prisms are of significance from a scientific and practical viewpoint. In this paper, we present a new experimental observation of flow-induced vibrations and associated spectral characteristics of a transversely oscillating D-section prism at an angle of attack α varying from 0° to 180°, where α = 0° and 180° represent the configuration with the upstream curved and flat part, respectively. The Reynolds number range is 530–9620, and the reduced velocity range is 1–32, based on the projected prism width in the crossflow direction. The mass ratio of the prism is 11.35, and the structural damping ratio in still water is 0.0036. Based on the response amplitudes and spectral traits, the D-prism exhibits the typical vortex-induced vibration (VIV) at α = 0°–30°, the first transition response at α = 45°–60°, the small-amplitude VIV response at α = 105°–135°, the second transition response at α = 150°–165°, the combined VIV-galloping response at α = 90°, and the pure galloping at α = 75° and 180°. The second transition response between low- and high-amplitude branches is found to be hysteretic and intermittent. Flow physics behind the D-prism responses are further elucidated by the wake patterns based on a high-speed camera and the flow velocity spectra downstream of the prism.
Ultrafast nonadiabatic excited-state intramolecular proton transfer in 3-hydroxychromone: A surface hopping approach
Authors: Nag Probal , Anand Neethu , Vennapusa Sivaranjana Reddy
Published: September 2021

We employ the ab initio molecular dynamics within the surface hopping method to explore the excited-state intramolecular proton transfer taking place on the coupled “bright” S1 (ππ*) and “dark” S2 (nπ*) states of 3-hydroxychromone. The nonadiabatic population transfer between these states via an accessible conical intersection would open up multiple proton transfer pathways. Our findings reveal the keto tautomer formation via S1 on a timescale similar to the O–H in-plane vibrational period (<100 fs). Structural analysis indicates that a few parameters of the five-membered proton transfer geometry that constitute the donor (hydroxyl) and acceptor (carbonyl) groups would be adequate to drive the enol to keto transformation. We also investigate the role of O–H in-plane and out-of-plane vibrational motions in the excited-state dynamics of 3-hydroxychromone.
A reliable chaos-based cryptography using Galois field
Authors: Nardo Lucas G. , Nepomuceno Erivelton G. , Bastos Gustavo T. , Santos Thiago A. , Butusov Denis N. , Arias-Garcia Janier
Published: September 2021

Chaos-based image encryption schemes have been extensively employed over the past few years. Many issues such as the dynamical degradation of digital chaotic systems and information security have been explored, and plenty of successful solutions have also been proposed. However, the impact of finite precision in different hardware and software setups has received little attention. In this work, we have shown that the finite precision error may produce distinct cipher-images on different devices. In order to overcome this problem, we introduce an efficient cryptosystem, in which the chaotic logistic map and the Galois field theory are applied. Our approach passes in the ENT test suite and in several cyberattacks. It also presents an astonishing key space of up to 24096. Benchmark images have been effectively encrypted and decrypted using dissimilar digital devices.
Frictional granular flows of rod and disk mixtures with particle shape distributions
Authors: Liu Yi , Yu Zhaosheng , Luo Kun , Guo Yu
Published: September 2021

Three-dimensional simulations of polydisperse shear flows of rod and disk mixtures are performed using the discrete element method. The effects of particle shape distribution on flow behaviors are investigated assuming that all particles have the same volume and density but different shapes in the simulations. The solid phase stresses and bulk friction coefficients show a strong dependence on the particle alignment and the structural anisotropy of interparticle contacts. The combined effects of interparticle friction and particle shape difference lead to larger stresses for mixtures of different particle shapes than the pure particle species in dense shear flows. For frictionless and frictional flows with particle shape distributions, it is observed that the particle fluctuating velocities follow non-Maxwellian distributions and the fluctuating kinetic energies are unequally partitioned among the different particle species.