bluuebunny/crossref_metadata_2025_split huggingface dataset:
New exact solutions to the Eddington-inspired-Born-Infeld equations for a relativistic perfect fluid in a Bianchi type I spacetime
Authors: Tadmon Calvin , Djiodjo-Seugmo Guichard 
Published: April 2022

Abstract
We consider a Bianchi type I physical metric g, an auxiliary metric q and a density matter ρ in Eddington-inspired-Born-Infeld theory. We first derive a system of second order nonlinear ordinary differential equations. Then, by a suitable change of variables, we arrive at a system of first order nonlinear ordinary differential equations. Using both the solution-tube concept for the first order nonlinear ordinary differential equations and the nonlinear analysis tools such as the Arzelá–Ascoli theorem, we prove an existence result for the nonlinear system obtained. The resolution of this last system allows us to obtain new exact solutions for the model considered. Finally, by studying the asymptotic behaviour of the exact solutions obtained, we conclude that this solution is the counterpart of the Friedman–Lemaître–Robertson–Walker spacetime in Eddington-inspired-Born-Infeld theory.
Protected two-qubit entangling gate with mechanical driven continuous dynamical decoupling
Authors: Sun Xue-Jian , Liu Wen-Xiao , Chen Hao , Wang Cheng-Yuan , Ma Hui-Zhong , Li Hong-Rong 
Published: April 2022

Abstract
In this work, we propose a high-fidelity phonon-mediated entangling gate in a hybrid mechanical system based on two silicon-vacancy color centers in diamond. In order to suppress the influence of the spin decoherence on the entangling gate, we use a continuous dynamical decoupling approach to create new dressed spin states, which are less sensitive to environmental fluctuations and exhibit an extended

T

2

*

spin dephasing time. The effective spin–spin Hamiltonian modified by the mechanical driving field and the corresponding master equation are derived in the dispersive regime. We show that in the presence of the mechanical driving field, the effective spin–spin coupling can be highly controlled. By calculating the entangling gate fidelity in the dressed basis, we find that once the mechanical field is turned on, the gate fidelity can be significantly improved. In particular, under an optimized spin-phonon detuning and a stronger Rabi frequency of the mechanical driving field, the two-qubit gate is capable of reaching fidelity exceeding 0.99. Moreover, by employing appropriate driving modulation, we show that a high-fidelity full quantum gate can be also realized, in which the initial and final spin states are on a bare basis. Our work provides a promising scheme for realizing high-fidelity quantum information processing.
Experimental and simulation studies of localization and decoding of single and double dipoles
Authors: Zhang Hao , Xu Minpeng , Zhang Chen , He Feng , Song Xizi , Chen Shanguang , Jian Xiqi , Ming Dong 
Published: April 2022

Abstract

Objective. Electroencephalography is a technique for measuring normal or abnormal neuronal activity in the human brain, but its low spatial resolution makes it difficult to locate the precise locations of neurons due to the volume conduction effect of brain tissue. Approach. The acoustoelectric (AE) effect has the advantage of detecting electrical signals with high temporal resolution and focused ultrasound with high spatial resolution. In this paper, we use dipoles to simulate real single and double neurons, and further investigate the localization and decoding of single and double dipoles based on AE effects from numerical simulations, brain tissue phantom experiments, and fresh porcine brain tissue experiments. Main results. The results show that the localization error of a single dipole is less than 0.3 mm, the decoding signal is highly correlated with the source signal, and the decoding accuracy is greater than 0.94; the location of double dipoles with an interval of 0.4 mm or more can be localized, the localization error tends to increase as the interval of dipoles decreases, and the decoding accuracy tends to decrease as the frequency of dipoles decreases. Significance. This study localizes and decodes dipole signals with high accuracy, and provides a technical method for the development of EEG.
Rectification in a mixture of active and passive particles subject to a ratchet potential
Authors: Derivaux Jean-François , Jack Robert L , Cates Michael E 
Published: April 2022

Abstract
We study by simulation a mixture of active (run-and-tumble) and passive (Brownian) particles with repulsive exclusion interactions in one dimension, subject to a ratchet (smoothed sawtooth) potential. Such a potential is known to rectify active particles at one-body level, creating a net current in the ‘easy direction’. This is the direction in which one encounters the lower maximum force en route to the top of a potential barrier. The exclusion constraint results in single-file motion, so the mean velocities of active and passive particles are identical; we study the effects of activity level, Brownian diffusivity, particle size, initial sequence of active and passive particles, and active/passive concentration ratio on this mean velocity (i.e. the current per particle). We show that in some parameter regimes the sign of the current is reversed. This happens when the passive particles are at high temperature and so would cross barriers relatively easily, and without rectification, except that they collide with ‘cold’ active ones, which would otherwise be localized near the potential minima. In this case, the reversed current arises because hot passive particles push cold active ones preferentially in the direction with the lower spatial separation between the bottom and top of the barrier. A qualitatively similar mechanism operates in a mixture containing passive particles of two very different temperatures, although there is no quantitative mapping between that case and the systems studied here.
Modelling and investigation of the stress state in a finite cylinder with a circular crack under sudden torsional loading
Authors: Demydov O V , Popov V G 
Published: April 2022

Abstract
This paper is devoted to the analysis of the dynamic stress state of a finite cylinder with an internal circular crack. One of the cylinder’s bases is fixed, and a time-dependent torque is applied to the other base. For solving this problem, a modified finite difference method was applied. This method consists in the difference approximation of only the time derivative. As a result, the original problem is reduced to a set of sequentially solved homogeneous boundary value problems. Their solutions contain an unknown displacement jump on the crack. The integral equation for the unknown jump is reduced to the Fredholm integral equation of the second kind, which was solved numerically. This numerical solution made it possible to obtain an approximate formula for calculating the stress intensity factor (SIF).
Methods for determining shear resistance by a system of cracks and old slip surfaces with the purpose to evaluate the stability of landslides
Authors: Hayroyan S G , Hayroyan H S 
Published: April 2022

Abstract
On slopes, landslide displacements mainly occur along bedding boundaries, lithogenetic and tectonic fractures, as well as along existing ancient slip surfaces, which are the weak zones and potential slip surfaces for new landslides.
According to experimental studies to determine the shear resistance by the standard and double cut test methods: a) without wetting the sliding surface, and b) by the wetting the sliding surface, we can conclude: when double- cutting the clay soils of a solid, semi-solid and tight-plastic consistency, the cohesion is mainly reduced, but the internal friction factor is slightly changed.
Double-cut tests of soft-plastic and flow-plastic clay soils have shown the cohesion and the internal friction factors are being changed insignificantly.
At the same time, taking into account the fact that under the condition τ > σ tan φ the soft-plastic and flowing-plastic clay soils undergo viscous-plastic deformations, we come to the following conclusion.
When developing the anti-landslide measures, independent of the consistency of the soils forming the slope, the τf
= σ tan φ component should be taken as the slip resistance index in the formula for calculating the slip resistance taking into account the condition Cc
+ Σ
w
= 0.
On a system of independent arguments for constitutive tensor functions on the growing surface in micropolar continuum
Authors: Murashkin E V 
Published: April 2022

Abstract
The present study is devoted to the boundary value problems statements for the growing materials with microstructural features. The general form of tensor relations on the propagating growing surface is derived as a consequence of the conservation laws of momentum and angular momentum. The necessary system of independent arguments of constitutive differential constraints on the growing surface in micropolar continuum is determined. A complete set of joint rational invariants of the system of tensors and vectors that determine the thermodynamics of the production process of a woven 3D material is given and discussed. An invariant-complete formulation of the constitutive relations on the growing surface is obtained.
Residual stresses calculation in a thermoelastoplastic torus after cooling
Authors: Dats E P , Kovalev V A , Murashkin E V 
Published: April 2022

Abstract
The present study deals with the boundary value problems under toroidal symmetry conditions. The residual stresses after cooling (unloading) in an elasto-plastic material are calculated. Throughout the paper the conventional Prandtl-Reuss model is generalised and used. The solution to the problem of hollow torus cooling under a temperature gradient is obtained and discussed. Analytical solutions, as an approximation of complete boundary value problem, describing residual deformations and stresses under conditions of toroidal symmetry are constructed and discussed.
Exact and beam solutions for a narrow clamped rectangle
Authors: Kovalenko M D , Menshova I V , Kerzhaev A P , Shulyakovskaya T D 
Published: April 2022

Abstract
The paper presents formulas describing an exact solution to the boundary value problem of the theory of elasticity in a rectangle in which the horizontal sides are rigidly clamped, and normal and tangential stresses are given on the vertical ones. Only an odd-symmetric deformation of the rectangle with respect to the horizontal axis of symmetry and an even-symmetric deformation of the rectangle with respect to the vertical axis of symmetry are considered. The paper is based on the previously obtained solutions for a free half-strip and a free rectangle.
Development of a mathematical model of a force actuator for the opening of a space structure with transformable configuration
Authors: Zimin V N , Krylov A V , Kuvyrkin G N , Shakhverdov A O 
Published: April 2022

Abstract
The prospects for the development of radio astronomy, solar energy, space communications, exploration of the Earth’s surface and other planets from space are currently associated with the creation of fundamentally new large-sized space structures. The inevitable complication of the design schemes of promising large-sized systems due to the increase in their operational functionality requires the development of mathematical models that adequately describe the mechanical properties of structures. When designing large-sized systems, the scheme of which allows for automatic configuration change of the structure, it is necessary to take into account shock loads. They inevitably arise when the working state of the structure fixes in orbit upon completion of the process of its opening. To ensure smooth, reliable and shock-free opening of large-sized space structures, it is proposed to use force actuators with active elements made of titanium nickelide material with a shape memory effect. During the tests of the active elements, the main parameters of the force actuator were determined: the generated force, the actuation time and the length of the working stroke. The length of the working stroke was determined by the change in the relative elongation of the active element of the force actuator during its heating. The conducted experimental and theoretical studies are aimed at developing a mathematical model of the functioning of an active element made of titanium nickelide with a shape memory effect for the opening of a space structure with transformable configuration.
Thermodynamic simulation of radioactive graphite combustion in water vapor
Authors: Barbin N M , Kobelev A M , Terent’ev D I , Alexeev S G , Titov S A 
Published: April 2022

Abstract
The paper analyzes the gas phase, the behavior uranium, the calculation of thermophysical properties during heating of nuclear reactor graphite containing various actinides. The study was carried out by thermodynamic modeling using the TERRA software package in the range from 423 to 2123 K at a constant pressure of 0.1 MPa. Up to a temperature of 623 K, the main components of the gas phase are water vapor, carbon dioxide, methane and hydrogen. Above 1023 K, the gas phase contains predominantly carbon dioxide and monoxide. It was revealed that in the range of 423-923 K uranium is present in the form of condensed compounds - uranium dioxide and uranyl chloride. Up to a temperature of 1623 K, uranium is present in the form of condensed uranium dioxide and calcium uranate. At temperatures above 2023 K, condensed uranium compounds are converted into gaseous and ionized compounds of uranium trioxide and dioxide. The thermophysical characteristics change unevenly up to a temperature of 923 K.
Numerical study of the effect of superheated steam supply during the combustion of liquid fuel in a burner on the reduction of harmful emissions
Authors: Kuznetsov V A , Dekterev Ar A , Anufriev I S , Minakov A V 
Published: April 2022

Abstract
In this work, the process of combustion of hydrocarbon fuel in the original burner of the evaporative type with the supply of superheated water vapor to the reaction zone is investigated using numerical modeling. N-heptane was used as a model fuel. The turbulent flow of gases was modeled on the basis of the RANS (Reynolds-averaged Navier–Stokes) approach. The combustion was simulated with the EDC (Eddy Dissipation Concept) model using a reduced chemical reaction mechanism. Calculation studies of the effect of steam on the processes occurring in the combustion chamber were carried out. Comparative analysis of the calculation results with experimental data showed good agreement in terms of the main integral parameters. The positive effect of the influence of steam injection into the active combustion zone of hydrocarbon fuel on the reduction of harmful emissions is shown.
Energy distribution and bremsstrahlung spectra of energetic electrons escaping from the ECR plasma with high energy input
Authors: Kiseleva E.M. , Izotov I. V. , Skalyga V.A. , Vybin S.S , Lapin R.L. 
Published: April 2022

Abstract
Electron energy distribution function (EEDF) is an important characteristic that defines the processes of plasma confinement and ionization. Understanding such processes is crucial for the proper tuning of ion sources. In the ECR plasma, the EEDF is significantly non-Maxwellian, and the exact shape remains still unknown. As the initial step towards the EEDF resolving, the energy distribution of the electrons lost from the magnetic mirror trap was directly measured in a wide range of neutral gas pressures and gyrotron powers along with bremsstrahlung spectra. A series of experiments were performed on the newly constructed Gasdynamic Ion Source for Multipurpose Operation (GISMO) facility allowing record-breaking specific energy input into the plasma. Obtained distributions showed unconventional behavior as the function of source parameters. The EEDF shape and the bremsstrahlung spectra showed a threshold qualitative change with the gyrotron power presumably as a result of the development of kinetic instabilities.
Experimental study on dynamic effects of H- and D- negative ions in an ECR-plasma source
Authors: Mitrou M , Svarnas P , Béchu S 
Published: April 2022

Abstract
The electrostatic probe-based photo-detachment technique with one or two laser beams can provide insight on the negative ion absolute densities and dynamics, respectively, in electronegative plasmas. In this work, this diagnostic is installed in the ECR-driven (2.45 GHz) negative ion source “Prometheus I” and details of the setup design along with main underlying physics are discussed. Potential origins of signal distortions and thus erroneous employment of this technique are demonstrated. Based on these observations, H- and D- negative ion densities and temperatures are measured in a reliable manner. The experiments are carried out for variable microwave power (2.45 GHz), at 1.33 Pa, unveiling two distinct kinetic equilibriums of the negative ions, in both gases, and an isotope effect.
H- and D- production efficiency in a multi-dipole ECR-plasma source as a function of gas pressure
Authors: Mitrou M , Svarnas P , Béchu S 
Published: April 2022

Abstract
The electron cyclotron resonance (ECR) negative ion source “Prometheus I” is operated either with high purity H2 (> 99.999%) or D2 (> 99.8%) to probe H- and D- ions, respectively, and examine the isotope effect within a wide range of gas pressure. These ions are predominantly formed in the bulk plasma by dissociative attachment (DA) of low-energy (cold) electrons to highly ro-vibrationally excited molecules. The latter result mainly from the radiative decay and excitation (EV) process sustained by high-energy (hot) electrons heated in the ECR zones. Langmuir probe and laser photo-detachment measurements are realized within the pressure range 0.27 to 2.67 Pa under constant microwave power (0.9 kW). It is revealed that: (i) the plasma potential, cold electron temperature, and cold electron density tend to be higher in deuterium; (ii) no pronounced difference in the hot electron density and temperature is found between the two plasmas; and (iii) overall a similar H- and D- negative ion yield (up to 6×109 cm-3; under the present conditions) is achieved. However, for equal plasma densities an isotope effect is exhibited showing higher H- density over the entire pressure range. Finally, the nH- / n ratio is constantly higher than the nD- / ne one and they both peak around 1.33 Pa.
Development and status of the FRIB 28 GHz SC ECRIS
Authors: Ren Haitao , Machicoane Guillaume , Bultman Nathan , Rao Xing , Morrison Phil , Omelayenko Mykola , Tobos Larry , Fogleman Jesse , Felice Helene , Hafalia Ray , Pan Heng , Prestemon Soren 
Published: April 2022

Abstract
T o meet a beam power requirement of 400 kW for heavy ions, a high intensity 28 GHz superconducting Electron Cyclotron Resonance (ECR) ion source is under development at the Facility for Rare Isotope Beams (FRIB) in collaboration with Lawrence Berkeley National Laboratory (LBNL). The magnet was built and tested at LBNL and integrated into the ion source cryostat on the FRIB high voltage platform. Magnet cooldown to 4.2K was completed successfully in December of 2020. The static heat load at 4.2K has been measured to be around 1.2 W, in good agreement with the design value. The heat load is managed through 2 Gifford-McMahon/Joule-Thomson (GM-JT) cryocoolers that have been in operation for several months. Magnet energization is scheduled in November of 2021. Warm components preparation and assembly test are ongoing in parallel. The ion source commissioning with 18 GHz Klystron shall start in December of 2021. Details of the ion source development, status, and commissioning plan will be presented in the paper.
A few ECRIS developments at LBNL
Authors: Xie D , Benitez J , Todd D 
Published: April 2022

Abstract
In addition to the ongoing investigation of bremsstrahlung radiation produced by energetic electrons in the superconducting Electron Cyclotron Resonance (ECR) ion source VENUS, the LBNL ion source group has pursued several other research topics since 2015 to explore potential advancements of ECR ion sources. Three of these activities are investigations into the benefits of non-cylindrical plasma chambers, the development of new high-temperature ovens that will efficiently produce the intense, metallic ion beams necessary for super heavy element production at the 88-Inch Cyclotron facility, and the finalization of the conceptual and engineering design of the superconducting NbTi magnet structure for the 4th generation, 45 GHz ECR ion source MARS-D. This article summarizes and briefly discusses the highlights of these ECRIS developments.
Low Z gas mixing effects of Ar and Xe multicharged ions in electron cyclotron resonance ion source
Authors: Tsuda K , Kubo W , Harisaki S , Anan M , Sato K , Owada I , Maenaka T , Kato Y 
Published: April 2022

Abstract
An electron cyclotron resonance (ECR) ion source (ECRIS) has wide applications such as cancer therapy and material synthesis. We have constructed a single ECRIS capable of producing various ions with low to high mass/charge ratio, and have been conducting various experiments. We focus on the efficient production of multicharged ions and aim to increase the yield of multicharged ions by new effects of electromagnetic waves in ECRIS. We investigated the possibility of selective heating to low Z ions under low Z gas mixing. Therefore, as a preliminary step of these experiments, the low Z gas mixing effect with rare gases are investigated. The optimum mixing ratio of the main gas Ar and the low Z gas He was investigated by varying the mixing ratio. The Ar multicharged ion beam current, impurity fraction and plasma parameters were measured. As a result, it was confirmed that the Ar multicharged ion yield was sufficient reproducibly increased by mixing He gas into Ar plasma. In addition, this from the measured plasma parameters is not an effect of the plasma parameters, but maybe a cooling effect.
High Performance 18 GHz ECR Ion Sources Development
Authors: Qian C , Sun L T , Lu W , Jia Z H , Yang T J , Zhu L , Zheng S J , Wang X D , Fang X , Li L B , Guo J W , Ma J D , Wang H , Feng Y C , Zhang X Z , Zhao H W 
Published: April 2022

Abstract
At present, ECR ion sources are developing towards higher frequency, higher magnetic field technology. However, 18 GHz is the highest optimal operation microwave frequency for room temperature ECR ion sources, which can meet the needs of most of the existing heavy ion facilities. After the success of the 18 GHz ECR ion source LECR4, we developed the upgraded version source LECR5 aiming for higher beam intensity and higher charge state ions. With a higher radial field, bigger plasma chamber volume, longer mirror length, and flexible Bmm field, promising results have been made at the power level of ∼2.1 kW@18 GHz, for instance, 81 eμA Bi32+, and 22 eμA Bi41+. This ion source has been recently used for the heavy ion facility SESRI (Space Environment Simulation Research Infrastructure) as the pre-injector ion source. High beam intensities and reasonable beam qualities have been demonstrated during the test platform. Inspired by this outcome, a hybrid 18 GHz ion source called HECRAL has been proposed aiming for the similar performance of SECRAL at 18 GHz. This paper will present the recent update of the LECR5 ion source commissioning. The design and preliminary results of the HECRAL ion source will be described.