bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental study on the dynamics and parameters of nanosecond laser-induced aluminum plasma
Authors: Xu Yongfeng , Yang Liang , Zhou Dongjian , Liu Benkang , Li Qingwei , Shi Wenbo , Jin Yuqi 
Published: April 2022

Abstract
In this paper, impulse measurement, spectral diagnostics, temporal evolution images and target ablation are employed to investigate the dynamic behaviors and parameters of Nd:YAG nanosecond laser-induced aluminum plasma at different pressures and laser fluences. The impulses and coupling coefficients generated by laser ablation increase firstly and then reduce with the decrease in pressure for the laser fluences of 17.22 J cm−2 and 20.94 J cm−2, but they only drop at 0.5 Torr for a laser fluence of 6.19 J cm−2. The fast exposure images captured by the high-speed camera and ICCD show that the plasma plumes present the separation at atmospheric pressure and expansion near vacuum, but last longer time at pressures of 150 Torr and 22 Torr. The duration and dynamic property of plasma are responsible for the impulse, as well as are mainly dependent on the characteristics of plasma parameters. Therefore, the electron density and electron temperature are obtained by Stark broadening method and Boltzmann plot, respectively. The change in the electron density is proportional to pressure and laser fluence. The variation trend of the crater depth and ablative mass with pressure is opposite to that of the electron density, which is ascribed to the plasma shielding effect caused by the inverse bremsstrahlung absorption mechanism. Besides, the electron temperature varies inversely with pressure in the detection range due to various recombination processes. This study provides an insight for clarifying the energy conversion mechanism and improving the laser propulsion performance.
Weak dipole moments of heavy fermions with flavor violation induced by Z′ gauge bosons
Authors: Montaño-Domínguez J , Quezadas-Vivian B , Ramírez-Zavaleta F , Tututi E S 
Published: April 2022

Abstract
A calculation of weak dipole moments of charged fermions of the standard model at the one-loop level, in the context of a general effective extended neutral current model with flavor changing

Z

′

f

i

f

¯

j

vertices, is presented. We give numerical predictions for the anomalous weak magnetic dipole moment

a

f
i

w

, and the weak electric dipole moment (WEDM)

d

f

i

w

, for the τ lepton and t quark. For several Z′ gauge bosons considered, we find that, for the τ lepton, the best prediction for the real part of

a

τ

w

is of the order of 10−9, while the imaginary part is four orders of magnitude below. The highest value for the WEDM,

d

τ

w

, corresponds to 10−26
e cm, for its real part, and the imaginary part is three orders of magnitude below. Moreover, we found for the top quark, that the best prediction for the real part of

a

t

w

is of the order of 10−7 and its imaginary part is of the order of 10−11. We also found that

d

t

w

is of the order of 10−26
e cm for its real part, and its imaginary part can be as high as 10−31
e cm.
Extraction of different temperatures and kinetic freeze-out volume in high energy collisions
Authors: Waqas M , Peng G X , Ajaz M , Haj Ismail A , Wazir Z , Li Li-Li 
Published: April 2022

Abstract
We analyze the transverse momentum (p
T) spectra, 1/N
ev[(1/2πp
T)d2
N/dydp
T], of kaon, proton, deuteron and triton in different centrality events in gold–gold (Au–Au) collisions at relativistic heavy ion collisions (RHICs) by Hagedorn thermal model and extracted the excitation function of effective temperature, kinetic freeze-out volume, initial temperature and kinetic freeze-out temperature. We perceived that the effective temperature, initial temperature and kinetic freeze-out temperature sharply increases from 7.7 GeV to 14.5 GeV and then remain static from 14.5–39 GeV, and this consistency may disclose that the onset energy of the phase transition of partial deconfinement and the whole deconfinement are 14.5 and 39 GeV, respectively. The kinetic freeze-out volume and mean transverse momentum grows with the rise of collision energy. Furthermore, the different extracted temperatures are observed in the order of time evolution of the interacting system, and they (as well as kinetic freeze-out volume) have an increasing trend from peripheral to central collisions. We also observed the mass dependence of the effective temperature and kinetic freeze-out volume where former increases while the later decreases for heavier particles, which indicates the early freeze-out of the heavier particles.
Towards an ecological modelling approach for assessing ionizing radiation impact on wildlife populations
Authors: Vives i Batlle J , Biermans G , Copplestone D , Kryshev A , Melintescu A , Mothersill C , Sazykina T , Seymour C , Smith K , Wood M D 
Published: April 2022

AbstractThe emphasis of the international system of radiological protection of the environment is to protect populations of flora and fauna. Throughout the MODARIA programmes, the United Nations’ International Atomic Energy Agency (IAEA) has facilitated knowledge sharing, data gathering and model development on the effect of radiation on wildlife. We present a summary of the achievements of MODARIA I and II on wildlife dose effect modelling, extending to a new sensitivity analysis and model development to incorporate other stressors. We reviewed evidence on historical doses and transgenerational effects on wildlife from radioactively contaminated areas. We also evaluated chemical population modelling approaches, discussing similarities and differences between chemical and radiological impact assessment in wildlife. We developed population modelling methodologies by sourcing life history and radiosensitivity data and evaluating the available models, leading to the formulation of an ecosystem-based mathematical approach. This resulted in an ecologically relevant conceptual population model, which we used to produce advice on the evaluation of risk criteria used in the radiological protection of the environment and a proposed modelling extension for chemicals. This work seeks to inform stakeholder dialogue on factors influencing wildlife population responses to radiation, including discussions on the ecological relevance of current environmental protection criteria. The area of assessment of radiation effects in wildlife is still developing with underlying data and models continuing to be improved. IAEA’s ongoing support to facilitate the sharing of new knowledge, models and approaches to Member States is highlighted, and we give suggestions for future developments in this regard.
The optimal beam-loading in two-bunch nonlinear plasma wakefield accelerators
Authors: Wang Xiaoning , Gao Jie , Su Qianqian , Wang Jia , Li Dazhang , Zeng Ming , Lu Wei , Mori Warren B , Joshi Chan , An Weiming 
Published: April 2022

Abstract
Due to the highly nonlinear nature of the beam-loading, it is currently not possible to analytically determine the beam parameters needed in a two-bunch plasma wakefield accelerator for maintaining a low energy spread. Therefore in this paper, by using the Broyden–Fletcher–Goldfarb–Shanno algorithm for the parameter scanning with the code QuickPIC and the polynomial regression together with k-fold cross-validation method, we obtain two fitting formulas for calculating the parameters of tri-Gaussian electron beams when minimizing the energy spread based on the beam-loading effect in a nonlinear plasma wakefield accelerator. One formula allows the optimization of the normalized charge per unit length of a trailing beam to achieve the minimal energy spread, i.e. the optimal beam-loading. The other one directly gives the transformer ratio when the trailing beam achieves the optimal beam-loading. A simple scaling law for charges of drive beams and trailing beams is obtained from the fitting formula, which indicates that the optimal beam-loading is always achieved for a given charge ratio of the two beams when the length and separation of two beams and the plasma density are fixed. The formulas can also help obtain the optimal plasma densities for the maximum accelerated charge and the maximum acceleration efficiency under the optimal beam-loading respectively. These two fitting formulas will significantly enhance the efficiency for designing and optimizing a two-bunch plasma wakefield acceleration stage.
A comparative analysis and an optimized structure of vertical GaN floating gate trench MOSFET for high-frequency FOM
Authors: Jaiswal Nilesh Kumar , Ramakrishnan V N 
Published: April 2022

Abstract
A vertical GaN floating gate trench MOSFET (FG-MOSFET) device structure has been optimized to obtain an enhanced high-frequency figure of merit (HF-FOM) than the conventional SGT- and TG-MOSFET. The floating gate (FG) electrode helps to reduce the surface electric field and binges in the middle of the drift layer. Using TCAD simulation, we demonstrate that with proper design of trench depth, drift doping, and field plate oxide thickness, the corresponding electric-field distribution for FG-MOSFET can be reduced to 2.3 MV cm−1. The proposed device has been designed for 600 V blocking voltage capability and with a specific on-resistance (

R

on

) as low as 0.73 mΩ cm2 due to the higher drift doping concentration. The HF-FOM (

Q

GD

×

R

on

) of FG-MOSFET shows a lower by two times and four times compared to SGT- and TG-MOSFET, due to FP oxide. Our results show that the FG-MOSFET device produces 15% and 47% reductions in the switching energy losses when compared with the similar current rated SGT- and TG-MOSFET devices, respectively.
Information theoretic limits of learning a sparse rule
Authors: Luneau Clément , Macris Nicolas , Barbier Jean 
Published: April 2022

Abstract
We consider generalized linear models in regimes where the number of nonzero components of the signal and accessible data points are sublinear with respect to the size of the signal. We prove a variational formula for the asymptotic mutual information per sample when the system size grows to infinity. This result allows us to derive an expression for the minimum mean-square error (MMSE) of the Bayesian estimator when the signal entries have a discrete distribution with finite support. We find that, for such signals and suitable vanishing scalings of the sparsity and sampling rate, the MMSE is nonincreasing piecewise constant. In specific instances the MMSE even displays an all-or-nothing phase transition, that is, the MMSE sharply jumps from its maximum value to zero at a critical sampling rate. The all-or-nothing phenomenon has previously been shown to occur in high-dimensional linear regression. Our analysis goes beyond the linear case and applies to learning the weights of a perceptron with general activation function in a teacher-student scenario. In particular, we discuss an all-or-nothing phenomenon for the generalization error with a sublinear set of training examples.
Strength, thermal resistance and electrical conductivity of aluminum-based composite wire
Authors: Yu Murashkin M , Sadykov D I , Mavlyutov A M , Magomedova D K , Kazykhanov V U 
Published: April 2022

Abstract
In this work, we demonstrate the possibility of producing a composite high strength and thermal resistant Al-based wire with ultrafine-grained (UFG) structure. Such composite wire consists of two aluminum alloys. Its clad is made of Al-1.17Mg-0.35Zr (wt.%) alloy, and the core is of Al-0.4Zr (wt.%). The specimens of Al alloys separately and as parts of a composite wire were subjected to thermomechanical treatment (TMT) that included annealing at 400°C, equal-channel angular pressing via “Conform” scheme (ECAP-C) and cold drawing (CD). The ratio between the core and clad materials in the composite wire was determined experimentally as well as calculated from the rule of mixtures (additivity). It has been shown that, an ultimate tensile strength over 360 MPa and a long-term operation temperature of 150°C can be achieved in a composite wire at a rational ratio between the chosen aluminum alloys with the UFG structures. Such combination of strength and thermal resistance is accompanied with an electrical conductivity of no less than 50% IACS in a composite wire.
Mathematical modeling of temperature stresses in a nonlocal thermoviscoelastic continuous medium
Authors: Kuvyrkin G N , Yu Savelyeva I , Kuvshinnikova D A 
Published: April 2022

Abstract
The improvement of the properties of structural and functional materials is associated with the synthesis of materials from structures with limiting values of properties (for example, extremely strong, refractory, thermostable, etc.). Such materials have an inhomogeneous structure, justified by the technological features of their preparation. In recent years, such materials have come to be called “structure–sensitive,” and the study of their thermomechanical characteristics has become possible within the framework of generalized mechanics of a continuous medium. Mathematical models describing such materials belong to the class of non-local models proposed by A. K. Ehringen. Now, there are few works on the use of nonlocal viscoelasticity, while many materials exhibit viscoelastic properties, even nonlocal viscoelastic properties, for example, solid propellants, composite materials, etc. The paper considers a mathematical model of a nonlocal thermoviscoelastic continuous medium. Using the finite element method, the temperature stress distributions are found for high-intensity pulsed heating of a nonlocal half-space.
Experimental study of the characteristics of heptane combustion in a high-speed steam jet
Authors: Sadkin I S , Kopyev E P , Mukhina M A , Anufriev I S 
Published: April 2022

Abstract
This paper is devoted to the experimental study of the characteristics of heptane combustion in a high-speed superheated steam jet. The completeness of the combustion under steam gasification conditions and the gas composition of the heptane combustion products cooled to room temperature were determined. The averaged temperature of the flame was measured. It is shown that the presence of superheated steam ensures high combustion efficiency and reduces emissions of nitrogen oxides in comparison with a heated air combustion. It is also shown that the organization of liquid fuel combustion in a high-speed steam jet ensures effective burning of fuel in the absence of nozzles and swirlers.
Integrated use of coal and coal-containing waste
Authors: Golubev V A , Platov I V 
Published: April 2022

Abstract
The current aggravation of such serious challenges as minimization of harmful emissions and suppression of the carbon footprint can be largely resolved through the more efficient and integrated use of fossil fuels with the accompanying production of additional products. Coals, including low-grade, carbon-containing, and vegetable waste, can be recycled into combustible gases, liquid fuels, and special types of coke, or smokeless fuel briquettes. On the other hand, this requires the development of new highly efficient technologies for the preparation, recycling, and use of fuels. The article discusses theoretical and experimental studies, and also presents schemes for thermal contact fuel preparation and recycling aimed at effective integrated use of fuels in standard boilers, and boilers with a circulating fluidized bed (CFB), or in special units with waste heat boilers. In CFB boilers, heat is transferred from the circulating particles to the processed fuel by direct thermal contact. In typical boilers, fuel preparation and recycling are carried out in conveyors with a heating jacket. Recycling of coals into special types of coke is carried out in a thermal-oxidative coking unit.
Interaction of components of the mineral part of Kansko-Achinsk coals in chamber combustion technologies with regard to thermodynamic and kinetic factors
Authors: Elsukov V K 
Published: April 2022

Abstract
The paper considers the physical and chemical properties of ash and slag waste generated in boilers of different types. Various literature sources and the results of industrial research conducted by the author are analyzed. Factors, influencing the properties of ash and slag wastes are formulated and considered. Issues to be solved for additional use of ash from Kansko-Achinsk coals (KAC) are formulated and partially considered in terms of reducing sulphur dioxide emissions. The article shows the possibility and expediency of low-temperature flaring of KAC (at temperatures of 1450 K) and the additional use of ash in technologies of chamber combustion, as well as the necessity of taking into account the changes in the electrophysical properties of ash produced during combustion with a high fraction of SO2 binding is shown. For the sulfur dioxide (SO2) binding reaction, the kinetic and differential equations are compiled and solved. Based on the solved equations, the efficiency of ash recirculation to the upper part of the cooling chamber of the BKZ 320-140 boiler was evaluated.
Experimental study of liquid hydrocarbon combustion under conditions of steam gasification in the presence of diluent gas
Authors: Kopyev E P , Sadkin I S , Mukhina M A , Shadrin E Yu , Krasinsky D V , Shimchenko S Yu 
Published: April 2022

Abstract
This research is devoted to the study of the influence of diluent gas presence on liquid hydrocarbons combustion at the example of diesel fuel. Carbon dioxide was used as a diluent gas. Superheated steam was gradually replaced by carbon dioxide, which had the same temperature and delivery location, which allows performing a comparative analysis of the burner operation at different parameters of the atomizer (superheated steam, carbon dioxide, and their mixture). Temperature profiles measures along the flame symmetry axis and combustion products analysis were performed. The presence of carbon dioxide does not affect the temperature distribution at different modes. A higher diluent gas flow rate causes a slight increase in the NOx content in the flue gases.
Determination of the ignition temperature of mechanically activated carbon of various degrees of metamorphism and type of grinding
Authors: Kuznetsov A V , Pochtar A S , Vinogradov S V , Burdukov A P 
Published: April 2022

Abstract
The experiments carried out using two methods of TGA (thermogravimetric analysis) made it possible to determine the ignition temperatures for brown coal, hard coal and anthracite treated both with activator mills (VCM, disintegrator) and with a standard hammer mill (initial coal). Practically all the results of coal ignition obtained by different methods correlate with each other. They show a decrease in the ignition temperature of micromilled coals during mechanically activated grinding. The analysis of the results of experimental studies made it possible to calculate kinetic parameters such as the ignition index, the maximum burning rate, the burnout index, and the comprehensive index. The data obtained are new and prove the effectiveness of mechanical activation treatment of coal fuel.
Numerical study of different electron density observed in Hydrogen and Deuterium ion source plasmas
Authors: Shibata T , Kato R , Nakano H , Hayashi K , Sato J , Miyamoto K , Hoshino K , Hatayama A 
Published: April 2022

Abstract
Sequences of hydrogen (H) and deuterium (D) experiments have been done by NIFS research and development negative ion source (RNIS) for the deuterium NBI development. In the experiments, the co-extracted electron current with the negative ions and the electron density in the plasma generation region in the D experiment have been around three times higher than that in the H experiment. To explain the difference of the electron density in the RNIS driver region, a zero-dimensional numerical model is developed in the present study. The model only focuses on the isotope effect for vibrationally excited level of electronically grounded state molecules and its relevant cross-sections. The calculation results show that difference of the ionization channel numbers via molecular vibrationally excited states could be a reason to enhance ionization rate in D plasma.
Experiment of two-frequency heating for production of multiply charged ion at compact ECR ion source
Authors: Muramatsu Masayuki , Nomura Shinji , Harisaki Shuhei , Kato Yushi , Abe Yasushi , Watanabe Mihiro , Katagiri Ken , Kitagawa Atsushi 
Published: April 2022

Abstract
Several research and developments have been performed at a compact ECR ion source (Kei3) with a fixed magnetic field at HIMAC. The Kei3 is a testing machine for application of Kei series developed for high-energy carbon-ion radiotherapy. It is difficult for Kei3 to produce ions that are heavier than carbon ion because it uses the same magnetic field distribution as the Kei series. In order to improve the beam current of multiply charged ions such as neon and argon, the two-microwave-frequency heating method was tested in the Kei3. Microwaves are introduced into the plasma chamber with a WR-90 rectangular waveguide. A traveling wave tube (TWT) amplifier made by the NEC (LD79X75A1) is used as the microwave source. The frequency band is 9.75-10.25 GHz and the maximum output power is 750 W. The WR-75 waveguide is also introduced from the upper part of the upstream vacuum chamber and installed on top of the existing the WR-90 waveguide. A TWT amplifier manufactured by the Xicom (XTRD-300IJ) was used as a microwave source for the two-microwave-frequency heating. The frequency band is 10-18 GHz and the maximum output power is 300 W. A beam test with oxygen, neon, and argon was performed in order to confirm the effect of two microwave frequency heating. In this test, we focused on O6+, Ne7+, and Ar9+ ions. We measured the dependence of the XTRD-300IJ microwave frequency and the microwave power of the LD79X75A1 on a charge state distributions.
Metal evaporation study using the GANIL high temperature oven for intense metal ion beams production
Authors: Bajeat O. , Barué C. , Dubois M. , Lemagnen F. , Maunoury L. , Michel M. , Osmond B. , Royet M. 
Published: April 2022

Abstract
A new resistive oven dedicated to the production of metal ion beams using ECR ion sources has been developed at GANIL. It aims to produce beams such as 58Niq+, 50Tiq+, 50Vq+ or 238Uq+ with ECR4 ion source on cyclotrons injectors and with Phoenix V3 ion source on Spiral 2facility. Typical intensity about 1.2 1013 pps is requested for the Super Separator Spectrometer (S3). Evaporated atom fluxes and their angular distributions have been measured on a dedicated test bench thanks to a quartz microbalance. These investigations were carried out using three crucibles with various exit caps geometries for which the fluxes and angular distributions display distinct behaviors. Based on those results, crucible is designed to obtain a high flux of atoms overlapping the ECR plasma while minimizing the atoms losses on the ion source chamber.
Experiments to improve the performance of the GTS-LHC ECR ion source
Authors: Kövener T , Küchler D , Mahner E , Scrivens R , Baris A , Pfeiffer S , Mourier L , Vollenberg W 
Published: April 2022

Abstract
The GTS-LHC 14.5 GHz ECR ion source provides the ion beam, which after acceleration in the ion injector complex, is injected into the LHC, as well as being sent to fixed target experiments at CERN. Two experiments have been performed on the source. The stainless steel plasma chamber has been sputter-coated with a rather thick layer of aluminium on the surface facing the plasma; and the lead micro-oven has been modified to avoid the build-up of lead-oxide on the oven outlet. Details of the changes will be given, and results of beam measurements will be shown, with particular attention on how the stability and oven-refill schedule is impacted by these changes.