bluuebunny/crossref_metadata_2025_split huggingface dataset:
Concurrent deep UV diffractions enabled by the Bragg condition and crystal symmetry in silica inverse opals
Authors: Rout Dipak , Kumar Govind , Vijaya R 
Published: December 2020

Abstract
Understanding the unexplored deep ultraviolet (UV) diffraction from photonic crystals will pave the way forward for developing diffractive optical elements in the deep UV wavelength range (190–250 nm). Herein we optically characterized the deep UV diffraction from our highly ordered 3D silica inverse opals fabricated by a co-assembly method and calculated their photonic band structures. Presence of a photonic stopband along their ΓL crystallographic direction is observed from the band structure. Presence of cracks and defects in these inverse opals impacts their deep UV photonic stopbands. Angle dependent diffraction measurements quantify the spacing of the (111) planes in the face-centered cubic inverse opal. Laser diffraction in the deep UV range yields a hexagonally symmetric six-spot pattern surrounding a central bright spot associated with Bragg diffraction in these inverse opals. Unlike earlier work, this feature has been observed with light at multiple wavelengths well within the stopband. Analysis of the deep UV diffraction pattern leads to the possibility of concurrent Bragg diffraction and (111) plane symmetry derived diffraction from our inverse opal PhC that are wavelength dependent.
AdVLP: unsupervised visible light positioning by adversarial deep learning
Authors: Hua Luchi , Zhuang Yuan , Gu Fuqiang , Qi Longning , Yang Jun 
Published: December 2020

Abstract
Visible light positioning (VLP) is a promising technique to bring location-based service for numerous Internet of Things applications. Recent advances in VLP have shown that machine learning (ML)-based positioning algorithms show satisfying performance in physical environments under highly noisy and interference-rich conditions. With so many ML methods proposed, one major concern is that trained models could fail due to environmental heterogeneity. In this paper, we propose AdVLP, a novel adversarial training method for VLP based on deep neural networks, to address the issue of the vulnerability of data-driven approaches, which happens when channel parameters change. Our proposed method, which is inspired by generative adversarial networks, manages to adapt the two domains of the source dataset and the target dataset. The channel parameters, e.g. the Lambertian order of light-emitting diode (LED) lights and a photodiode, the LED power as well as the location error of the lights, were discussed. We observed in experiments that the accuracy of a neural network method would decrease as the bias of the parameters became larger. Secondly, a higher dimension of the parameter change would make the neural network method more vulnerable. However, our proposed approach could achieve substantial improvement in positioning accuracy.
Understanding Newton’s cradle. II: exploring a real cradle
Authors: Cross Rod , Gauld Colin 
Published: December 2020

Abstract
Newton’s cradle is a well-known physics toy that is commonly used by teachers to demonstrate conservation laws in mechanics. It can also be used to investigate the physics of colliding objects, by recording motion of the balls on video film. Various experiments are described using 3-ball and 5-ball cradles, showing how different types of collision can be investigated depending on whether the balls are touching or separated. The sequence of collisions was examined as a function of time, with the surprising observation that very small gaps between the balls, invisible on video film, make a significant difference to the collision dynamics. Additional experiments illustrate the effects of changes in ball stiffness and the mass of the middle ball and provide an introduction for students and teachers into possible research projects. Each experiment is illustrated with a supplementary video.
An ultrathin-barrier AlGaN/GaN heterostructure: a recess-free technology for the fabrication and integration of GaN-based power devices and power-driven circuits
Authors: Huang Sen , Wang Xinhua , Liu Xinyu , Sun Qian , Chen Kevin J 
Published: December 2020

Abstract
An AlGaN-recess-free, ultrathin-barrier (UTB) AlGaN (<6 nm)/GaN heterostructure is presented for the fabrication and integration of AlGaN/GaN enhancement/depletion-mode (E/D-mode) heterojunction field-effect transistors (HFETs), and metal–insulator-semiconductor HFETs (MIS-HFETs). The 2D electron gas in the access region of the UTB-AlGaN/GaN (MIS)HFETs can effectively be recovered by a low-pressure chemical-vapor-deposited SiNx passivation layer (LPCVD-SiNx), which is capable of introducing about 2.75 × 1013 cm−2 positive fixed charges at the LPCVD-SiNx/(Al)GaN interface. LPCVD-SiNx can also serve as a good gate insulator for D-mode MIS-HFETs. Using the self-terminating etching of LPCVD-SiNx on III-nitride as well as a low-damage remote plasma pretreatment, high uniformity E-mode HFETs and low-hysteresis E-mode MIS-HFETs have been fabricated using the GaN-on-Si platform. E/D-mode MIS-HFET inverters with a large logic swing have also been demonstrated on this platform. The UTB-AlGaN/GaN heterostructure is an attractive technology platform for the on-chip integration of power and RF devices with power-driven circuits for GaN-based smart power integrated circuits.
A design framework for actively crosslinked filament networks
Authors: Fürthauer Sebastian , Needleman Daniel J , Shelley Michael J 
Published: December 2020

Abstract
Living matter moves, deforms, and organizes itself. In cells this is made possible by networks of polymer filaments and crosslinking molecules that connect filaments to each other and that act as motors to do mechanical work on the network. For the case of highly cross-linked filament networks, we discuss how the material properties of assemblies emerge from the forces exerted by microscopic agents. First, we introduce a phenomenological model that characterizes the forces that crosslink populations exert between filaments. Second, we derive a theory that predicts the material properties of highly crosslinked filament networks, given the crosslinks present. Third, we discuss which properties of crosslinks set the material properties and behavior of highly crosslinked cytoskeletal networks. The work presented here, will enable the better understanding of cytoskeletal mechanics and its molecular underpinnings. This theory is also a first step toward a theory of how molecular perturbations impact cytoskeletal organization, and provides a framework for designing cytoskeletal networks with desirable properties in the lab.
Coherence protection and decay mechanism in qubit ensembles under concatenated continuous driving
Authors: Wang Guoqing , Liu Yi-Xiang , Cappellaro Paola 
Published: December 2020

Abstract
Dense ensembles of spin qubits are valuable for quantum applications, even though their coherence protection remains challenging. Continuous dynamical decoupling can protect ensemble qubits from noise while allowing gate operations, but it is hindered by the additional noise introduced by the driving. Concatenated continuous driving (CCD) techniques can, in principle, mitigate this problem. Here we provide deeper insights into the dynamics under CCD, based on Floquet theory, that lead to optimized state protection by adjusting driving parameters in the CCD scheme to induce mode evolution control. We experimentally demonstrate the improved control by simultaneously addressing a dense nitrogen-vacancy (NV) ensemble with 1010 spins. We achieve an experimental 15-fold improvement in coherence time for an arbitrary, unknown state, and a 500-fold improvement for an arbitrary, known state, corresponding to driving the sidebands and the center band of the resulting Mollow triplet, respectively. We can achieve such coherence time gains by optimizing the driving parameters to take into account the noise affecting our system. By extending the generalized Bloch equation approach to the CCD scenario, we identify the noise sources that dominate the decay mechanisms in NV ensembles, confirm our model by experimental results, and identify the driving strengths yielding optimal coherence. Our results can be directly used to optimize qubit coherence protection under continuous driving and bath driving, and enable applications in robust pulse design and quantum sensing.
Theoretical studies on the elastic scattering of e± off the ions of xenon isonuclear series
Authors: Khandker Mahmudul H , Billah M Masum , Watabe Hiroshi , Haque A K F , Uddin M Alfaz 
Published: December 2020

Abstract
This work presents the calculations of differential, integrated elastic and momentum transfer cross sections for the elastic scattering of electrons from the ions of xenon isonuclear series over the incident energy range 1 eV–1000 eV. Coulomb glory, the amplification of elastic backscattering of electrons from positive ions owing to the electrostatic screening of nuclear potential by atomic electrons, is investigated throughout the ionic series of xenon, argon and neon. Cross sections for the angular distribution of elastically scattered positron from selected xenon ions are also calculated. Energy dependency of differential cross sections and Sherman functions are predicted for both the projectiles and a comparison is presented to exhibit the dissimilarity arising out of the difference of the interactions of the projectiles with ions. The theoretical methodology of this work employs the Dirac relativistic partial wave analysis using a complex optical potential, comprising static, exchange, polarization and imaginary components, and a pure Coulomb potential. The results obtained show reasonable agreements with the available experimental data and other theoretical calculations.
The simulate of the stratification of an explosive mixture of hydrogen and air in the RBMK-1000 spent-fuel storage pool
Authors: Osipov A M , Bragin E U , Prochorenkov S V , Tupotilov I A 
Published: December 2020

Abstract
Currently, in Russia, codes with concentrated parameters are used as software tools to justify the hydrogen explosion safety of nuclear power units, which use the concept of “average concentration of hydrogen” in the calculated volume and do not take into account the stratification of hydrogen, due to which local concentrations of hydrogen can significantly exceed the “average”. This paper presents the hydrogen explosion safety analysis results during a beyond-design accident in the RBMK-1000 spent-fuel storage pool taking into account local concentrations of gas components using the gas dynamic code ANSYS FLUENT. The vapor-gas mixture propagation problem in the spent-fuel storage pool was solved in a two-dimensional approximation. The following sources of hydrogen were considered radiolysis hydrogen generation, hydrogen generation by reducing its solubility in water and the vapor-zirconium reaction. As a result of modeling, the possible accumulation areas of an explosive mixture and their sizes were determined. It is shown that under certain combinations of boundary conditions, due to the presence of convective flows, an explosive concentration is not achieved even if the mixture components stratification is taken into account.
Modernization of the CHAIN code for fission gas release calculation
Authors: Smirnova A K , Krayushkin A V 
Published: December 2020

Abstract
The issue of a quantitative assessment of the fission products release from the fuel is one of the important part of the analysis of the radiation consequences of accidents. In the reactor fission products that accumulate as a result of the fission reaction are contained within the fuel elements. The article discusses the modification of the CHAIN code for the calculation of the isotopic composition of the fuel, which was added a subroutine calculating the fission gas release from the fuel. The subroutine is based on the diffusion equation, the modification of which makes it possible to take into account the release of radionuclides from uranium dioxide of fuel elements. The coefficients in the diffusion equation were selected experimentally. The results of the calculations for two verification tests of the modified code are also presented. Comparisons of the calculation results of the code were carried out for emergency fuel heating and during normal operation of the reactor.
Comparison of the operation of the equations of the surface harmonics method and the finite difference method in the test problem
Authors: El’shin A V , Koreshkova A U , Makovets A K 
Published: December 2020

Abstract
Currently, one of the main methods of neutron-physical calculation of the reactor is the homogenization method, in which after obtaining effective small-group characteristics of cells, the heterogeneous core, in fact, turns into a piecewise homogeneous one. To find the distribution of neutrons in such a zone, the diffusion equation is solved by finite-difference (or nodal) methods. One of the methods justifying this approach is the surface harmonics method (SHM), which in the initial period of its development acted as a justification and refinement of the homogenization method. In the simplest versions of the SHM, the resulting finite-difference equations are reduced to a form similar to the finite-difference approximation of the diffusion equation. It is interesting to compare in the simplest cases the advantages and disadvantages of a simple finite-difference approximation of the diffusion equation and the finite-difference equations obtained using SHM. An analytical comparison is made using the example of two-dimensional geometry. To do this, the paper briefly describes how to obtain equations in SHM.
Advanced Nuclear Security Program at The Joint Institute for Power and Nuclear Research - Sosny
Authors: Korbut T , Zenevich V , Kravchenko M , Bobkova M , Zubets I 
Published: December 2020

Abstract
The Republic of Belarus is a participant in global efforts for nuclear non-proliferation, ensuring the preservation of nuclear materials and countering nuclear terrorism. In accordance with the Decree of the President of the Republic of Belarus No. 124 dated March 29, 2011, the Joint Institute for Power and Nuclear Research – Sosny of National Academy of Science of Belarus is the operator (operating organization) of a number of critical and subcritical nuclear facilities, radiation installations and fresh nuclear fuel storage, containing highly enriched uranium fuel. A nuclear security culture is an important necessary constituent of the nuclear and radiation security. The authors of this paper will report on the approach the Institute is taking in regard to advancing nuclear security program, what are the Institute’s goals and objectives, and what steps are being taken to support effective the physical protection system at the Scientific Institution “JIPNR - Sosny” and another operating organization in the Republic of Belarus. The range of measures aimed at reducing the likelihood of internal violators activity, early detection of potential internal violators and preventing from causing harm are presented.
Possibilities of Better Utilization of MOX fuel in VVER type reactors by optimizing neutron spectrum
Authors: Abuqudaira T M , Stogov Y V 
Published: December 2020

Abstract
The introduction of MOX fuel in modern nuclear fuel cycles has posed attention in all leading nuclear countries. However, the introduction of plutonium in the fuel loading in light water reactors has neutron-physical limitations. Improve the consumption of plutonium in MOX fuels is one of the important issues that have to be studied to decrease the risk of proliferation resistance. The impact of varying neutron spectrum on the discharged plutonium was studied through the variation of the fuel pellets diameter in a VVER type MOX fuel assembly without changing the lattice pitch. Neutronic calculations were performed using: MCU, Serpent, and GETERA codes. It was shown that the neutron spectrum plays a dominant role in the consumption and production of nuclides. Also, the usage of assemblies with high moderator to fuel volume ratio burned higher amounts of fissile plutonium in comparison with assemblies with low moderator to fuel volume ratio.
Physical aspects for involvement of thermonuclear reactors into nuclear power systems
Authors: Kulikov G G , Shmelev A N , Apse V A , Kulikov E G 
Published: December 2020

Abstract
The paper analyzes a possibility to involve hybrid thermonuclear reactors into the existing nuclear power systems. The possibility is related with production of non-traditional nuclear fuel in thorium blanket of hybrid thermonuclear reactors on D-T plasma. Non-traditional peculiarity of such a fuel consists in significant amounts of some non-traditional isotopes, namely231Pa and232U, together with traditional uranium isotope233U in the fuel. High-energy (14.1 MeV) thermonuclear neutrons can provide accumulation of significant231Pa and232U quantities through threshold (n,2n) and (n,3n) reactions. The promising features of the non-traditional fuel composition for nuclear power thermal reactors, basic component of the existing world-wide nuclear power industry, are defined by the following factors. As is known, 233U is able to provide more economical neutron balance in thermal reactors than235U and reactor-grade plutonium. The better neutron balance can result in higher values of the fuel breeding ratio and, as a consequence, in relaxation of the thermal reactors fuel self-sustainability problem. Isotopes231Pa and232U, being fertile and moderate fissionable nuclides, are able to stabilize time-dependent evolution of the thermal reactors power, prolong the thermal reactors lifetime through higher values of the fuel burn-up. Isotope232U, being intense α-emitter, is able to prevent any attempts for unauthorized usage of233U in nuclear explosive devices, i.e.232U can strengthen regime of nuclear non-proliferation. Thus, the hybrid thermonuclear reactors on D-T plasma with thorium blanket can be involved into nuclear power systems for generation of non-traditional, very promising fuel compositions for traditional nuclear power reactors.
Spatial-temporal characteristics of temperature fluctuations of turbulent fluid flow and velocity measurements based on them
Authors: Sardov PA , Belavina E A , Belyaev I A 
Published: December 2020

Abstract
The paper describes the temperature cross-correlation velocimetry method applied to flows of water or liquid metal. The technique allows us to measure temperature waveforms and averaged longitudinal velocity in a flow simultaneously. This approach is a simple and reliable method for measuring the velocity in flows of opaque coolants. At the same flow parameters, liquids of different origins provide non-similar spatial-temporal characteristics having a different impact on the applicability of the temperature correlation method. This work is devoted to the development of practical methods allowing to form a set of specific recommendations on the application of the technique of temperature correlation velocimetry and to determine the metrological characteristics of the technique in various conditions. Calibration was carried out using water and mercury as a model liquid. Used experimental facility and measuring system are described, accompanied by a detailed description of the developed temperature-correlation sensor. Measuring directly from within a flow is made possible by a unique micro thermocouple immersion probes technique. Data obtained are presented as fields of temperature and intensity of temperature fluctuations. Autocorrelation and cross-correlation functions are compared and analysed for two studied fluids under identical conditions.
Determining the critical concentration of boric acid and the time of its onset when reaching to minimum controllable power for VVER
Authors: Al-Shamayleh A I , Solovyov D A , Semyonov A A , Shcukin N V , Djaroum B , Tanash H A , Molev I A 
Published: December 2020

Abstract
Startup to minimum controllable power level (criticality approach) is one of the most hazardous nuclear operations during operation. In particular, the spontaneous and unauthorized startup to minimum controllable power is very dangerous, and it occurs as a result of some technological operations or changes in technological regimes. Currently, there are codes for neutron-physical calculations at NPPs with VVER, such as reactor simulator (IR) and BIPR-7A. These codes calculate the boric acid critical concentration without relying on excore ionization detectors data, which may result in inaccuracies in determining the critical concentration. In addition, feeding the primary circuit with clean condensate must be stopped at least 15 minutes before is reached, and these codes do not calculate the time to reach the critical state. As a result, the idea arose to develop a code that would predict the time to reach the critical state and the critical concentration of boric acid only using the measuring equipment readings without reliance on additional calculations.
Modeling of BN-600 Hybrid Core Benchmark (HEX-Z) with MCU-PTR and SERPENT 2
Authors: Bahdanovich R B , Abu Sondos M A , Kaprinayova K , Farkas G , Tikhomirov G V 
Published: December 2020

Abstract
For the computational support of innovative projects it is necessary to use high-fidelity codes, which must be verified and validated. In Russia, MCU and SERPENT codes are widely used. The MCU code was previously chosen as the ‘Proryv’ project code. Both of these codes are used for calculation of fast reactors, although they are certified for thermal reactors. Therefore, there is a need to show how accurately they allow calculating the characteristics of fast reactors. For cross-verification of these codes, the main characteristics of the benchmark of BN-600 reactor with a hybrid core were calculated: neutron multiplication factors, reactivity coefficients, distribution of energy release over zones, reaction rates. The values of the neutron multiplication factors for various states of the model obtained with the MCU-PTR are systematically higher than the values obtained with the SERPENT 2 (for majority of the states by 0.4%). The values of the reactivity coefficients have the same sign, however, difference between both codes can reach 160% and if compared with the benchmark – 181%. For the majority of reactivity coefficients this compares with the distribution of the results presented in the benchmark. The MCU results are closer to the benchmark than the Serpent ones.
Hydraulic resistance of an annular channel with a rectangular roughness on the wall
Authors: Medgedem S , Korsun A S , Fedoseev V N , Pisarevskii M I , Pisarevskaya Y N 
Published: December 2020

Abstract
This paper provides a brief overview of approaches to calculating the hydraulic resistance coefficient of a channel with rough walls and describes their advantages and disadvantages. One of the most popular engineering approaches is based on integral characteristics. By the influence of roughness, the logarithmic velocity profile changes, which is fully described by the second constant. It determines the interaction of a turbulent flow with a rough wall. Its numerical value depends on a large number of factors, such as geometry of the roughness protrusion, the dimensionless height of the protrusion, its shape, angle of attack, and so on. Getting a generalized dependence of this kind is an actual task of rough channel hydraulics. In this paper, the second constant of the logarithmic velocity profile is numerically calculated using turbulence models. A symmetric model of a developed turbulent flow in an annular channel with a rectangular roughness on the wall is implemented. Roughness was applied to the surface of the rod, the inner surface of the pipe was smooth. The result of numerical simulation was the obtained velocity profile, which was used to determine the numerical value of the second constant. The obtained results are satisfactory agreement with the experimental data.