bluuebunny/crossref_metadata_2025 huggingface dataset:
What Caused the Bhopal Gas Tragedy? The Philosophical Importance of Causal and Pragmatic Details
Authors: Hanley Brian J.
Published: February 2021

In cases in which many causes together bring about an effect, it is common to select some as particularly important. Philosophers since Mill have been pessimistic about analyzing this reasoning because of its variability and the multifarious causal and pragmatic details of how it works. I argue Mill was right to think these details matter but wrong that they preclude philosophical analysis of causal selection. I show that analyzing the pragmatic details of scientific debates about the important causes of the Bhopal Gas Tragedy can illuminate causal reasoning about disasters and shed new light on causality and causal selection.
Fluoropolymer coatings deposited on rotating cylindrical surfaces by HW CVD: experiment and simulation
Authors: Bykov Nikolay Y , Ronshin Fedor V , Safonov Alexey I , Starinskiy Sergey V , Sulyaeva Veronica S
Published: February 2021

The hot wire chemical vapor deposition method has been adapted to deposit fluoropolymer coatings on small-radius rotating surfaces. The influence of the rotational frequency of a cylindrical sample during the deposition process on the formation of a layer of fluoropolymer coating was studied. It was found that the rotational frequency of the cylindrical sample significantly changed the morphology of the resulting coating. It was shown that with an increase in the sample’s rotational frequency from 1 to 100 rpm, the deposition rate decreased and the coating structure degraded. To establish the reasons for this effect, a numerical study of the flow around a rotating cylindrical sample was carried out for a range of low gas velocities and densities in the reactor. The simulations are based on solving the Navier–Stokes equation with no slip and velocity slip boundary conditions for a rotating surface. It was found that the main reason for the decrease in the deposition rate was associated with the effect of the formation of a closed circulation flow region above the sample’s surface during rotation. The dependence of the characteristic size of this region on the rotational frequency of the cylinder sample was close to linear. The effects of surface boundary conditions were also analyzed.
Recent progress in deep-depletion diamond metal–oxide–semiconductor field-effect transistors
Authors: Masante Cédric , Rouger Nicolas , Pernot Julien
Published: February 2021

Diamond has been explored to develop prototype field-effect transistors (FETs). At present, various architectures that are suited to high temperature and high-radiation environments are still under investigation for power electronics applications. Recently, the deep-depletion diamond metal–oxide–semiconductor FET (D3MOSFET) concept has been introduced and demonstrated to be a good candidate for designing efficient diamond MOSFETs. In this paper, a general introduction to the concept of deep depletion is given. The key issues concerning the design and fabrication of this kind of diamond MOSFET are then described and discussed in terms of quasi static performance (the ‘on’ and ‘off’ states). A demonstration of the working regimes of a fabricated normally-on D3MOSFET is described, which reached a critical field of at least 5.4 MV cm−1 at a drain–source bias of −175 V, without electric field relaxation structures. The minimum on-state resistance was measured and found to be R

ON,S
 = 50 mΩ cm2 at 250 ∘C. Finally, the D3MOSFET is contextualized as part of a global research effort to develop diamond power FETs. Some of the main challenges regarding the fabrication of competitive D3MOSFETs and, more generally, diamond power devices are discussed.
Perfect absorber with separated ‘dielectric–metal–ground’ metamaterial structure
Authors: Wang Han , Yan Bo , Jin Huizhen , Wang Zhigang , Guo Lanjun , Li Boyan , Yu Bo , Gong Cheng
Published: February 2021

A metamaterial perfect absorber whose effective thickness is less than 1/1000 of the operating wavelength is proposed. Different from the traditional ‘metal–dielectric–ground’ type metamaterial absorber, it adopts a novel ‘dielectric–metal–ground’ structure, and the ‘dielectric–metal’ structure is separated from the ‘ground’. Through this design, the effective thickness of the absorber is reduced to about 1/2200 of the wavelength. This will make the absorber suitable for imaging and sensing applications. Next, a bi-material cantilever absorber based on the proposed structure is designed and fabricated to demonstrate the high absorption properties in the case of ultra-thin thickness. In addition, a reflective spectroscopy system based on a vector network analyzer is built to test the absorption performance. The measured results, showing that it has an absorptivity of close to 97% at 94 GHz, are in good agreement with simulations.
Absence of local moments in the kagome metal KV3Sb5 as determined by muon spin spectroscopy
Authors: Kenney Eric M , Ortiz Brenden R , Wang Chennan , Wilson Stephen D , Graf Michael J
Published: February 2021

We have carried out muon spin relaxation and rotation measurements on the newly discovered kagome metal KV3Sb5, and find a local field dominated by weak magnetic disorder which we associate with the nuclear moments present, and a modest temperature dependence which tracks the bulk magnetic susceptibility. We find no evidence for the existence of V4+ local moments, suggesting that the physics underlying the recently reported giant unconventional anomalous Hall effect in this material warrants further studies.
Nanometre imaging of Fe3GeTe2 ferromagnetic domain walls
Authors: Hopkinson David G , Seki Takehito , Clark Nicholas , Chen Runze , Zou Yichao , Kimura Ayumi , Gorbachev Roman V , Thomson Thomas , Shibata Naoya , Haigh Sarah J
Published: February 2021

Fe3GeTe2 is a layered crystal which has recently been shown to maintain its itinerant ferromagnetic properties even when atomically thin. Here, differential phase contrast scanning transmission electron microscopy is used to investigate the domain structure in a Fe3GeTe2 cross-sectional lamella at temperatures ranging from 95 to 250 K and at nanometre spatial resolution. Below the experimentally determined Curie temperature (T
C) of 191 K, stripe domains magnetised along 〈0001〉, bounded with 180◦ Bloch type domain walls, are observed, transitioning to mixed Bloch−Néel type where the cross-sectional thickness is reduced below 50 nm. When warming towards T
C, these domains undergo slight restructuring towards uniform size, before abruptly fading at T
C. Localised loss of ferromagnetic order is seen over time, hypothesised to be a frustration of ferromagnetic order from ambient oxidation and basal cracking, which could enable selective modification of the magnetic properties for device applications.
Synthesis of coralloid carbon nitride polymers and photocatalytic selective oxidation of benzyl alcohol
Authors: Gu Qian , Jiang Pingping , Shen Yirui , Leng Yan , Wai Phyu Thin , Zhang Kai , Haryono Agus
Published: February 2021

Polymeric carbon nitride (C3N4) is currently the most potential nonmetallic photocatalyst, but it suffers from low catalytic activity due to rapid electron–hole recombination behavior and low specific surface area. The morphology control of C3N4 is one of the effective methods used to achieve higher photocatalytic performance. Here, bulk, lamellar and coralloid C3N4 were synthesized using different chemical methods. The as-prepared coralloid C3N4 has a higher specific surface area (123.7 m2 · g−1) than bulk (5.4 m2 · g−1) and lamellar C3N4 (2.8 m2 · g−1), thus exhibiting a 3.15- and 2.59-fold higher photocatalytic efficiency for the selective oxidation of benzyl alcohol than bulk and lamellar C3N4, respectively. Optical characterizations of the photocatalysts suggest that coralloid C3N4 can effectively capture electrons and accelerate carrier separation, which is caused by the presence of more nitrogen vacancies. Furthermore, it is demonstrated that superoxide radicals (·O2
−) and holes (h+) play major roles in the photocatalytic selective oxidation of benzyl alcohol using C3N4 as a photocatalyst.
Rotational dynamics of proteins in nanochannels: role of solvent’s local viscosity
Authors: Haridasan Navaneeth , Sathian Sarith P
Published: February 2021

Viscosity variation of solvent in local regions near a solid surface, be it a biological surface of a protein or an engineered surface of a nanoconfinement, is a direct consequence of intermolecular interactions between the solid body and the solvent. The current coarse-grained molecular dynamics study takes advantage of this phenomenon to investigate the anomaly in a solvated protein’s rotational dynamics confined using a representative solid matrix. The concept of persistence time, the characteristic time of structural reordering in liquids, is used to compute the solvent’s local viscosity. With an increase in the degree of confinement, the confining matrix significantly influences the solvent molecule’s local viscosity present in the protein hydration layer through intermolecular interactions. This effect contributes to the enhanced drag force on protein motion, causing a reduction in the rotational diffusion coefficient. Simulation results suggest that the direct matrix-protein non-bonded interaction is responsible for the occasional jump and discontinuity in orientational motion when the protein is in very tight confinement.
Efficient radiation dose reduction in whole-brain CT perfusion imaging using a 3D GAN: performance and clinical feasibility
Authors: Dashtbani Moghari Mahdieh , Zhou Luping , Yu Biting , Young Noel , Moore Krystal , Evans Andrew , Fulton Roger R , Kyme Andre Z
Published: February 2021

Dose reduction in cerebral CT perfusion (CTP) imaging is desirable but is accompanied by an increase in noise that can compromise the image quality and the accuracy of image-based haemodynamic modelling used for clinical decision support in acute ischaemic stroke. The few reported methods aimed at denoising low-dose CTP images lack practicality by considering only small sections of the brain or being computationally expensive. Moreover, the prediction of infarct and penumbra size and location—the chief means of decision support for treatment options—from denoised data has not been explored using these approaches. In this work, we present the first application of a 3D generative adversarial network (3D GAN) for predicting normal-dose CTP data from low-dose CTP data. Feasibility of the approach was tested using real data from 30 acute ischaemic stroke patients in conjunction with low dose simulation. The 3D GAN model was applied to 643 voxel patches extracted from two different configurations of the CTP data—frame-based and stacked. The method led to whole-brain denoised data being generated for haemodynamic modelling within 90 s. Accuracy of the method was evaluated using standard image quality metrics and the extent to which the clinical content and lesion characteristics of the denoised CTP data were preserved. Results showed an average improvement of 5.15–5.32 dB PSNR and 0.025–0.033 structural similarity index (SSIM) for CTP images and 2.66–3.95 dB PSNR and 0.036–0.067 SSIM for functional maps at 50% and 25% of normal dose using GAN model in conjunction with a stacked data regime for image synthesis. Consequently, the average lesion volumetric error reduced significantly (p-value <0.05) by 18%–29% and dice coefficient improved significantly by 15%–22%. We conclude that GAN-based denoising is a promising practical approach for reducing radiation dose in CTP studies and improving lesion characterisation.
High intrinsic lattice thermal conductivity in monolayer MoSi2N4
Authors: Yu Jihai , Zhou Jian , Wan Xiangang , Li Qingfang
Published: February 2021

Very recently, a novel two-dimension (2D) MXene, MoSi2N4, was successfully synthesized with excellent ambient stability, high carrier mobility, and moderate band gap (2020 Science
369 670). In this work, the intrinsic lattice thermal conductivity of monolayer MoSi2N4 is predicted by solving the phonon Boltzmann transport equation based on the first-principles calculations. Despite the heavy atomic mass of Mo and complex crystal structure, the monolayer MoSi2N4 unexpectedly exhibits a quite high lattice thermal conductivity over a wide temperature range between 300 to 800 K. At 300 K, its in-plane lattice thermal conductivity is 224 Wm−1 K−1. The detailed analysis indicates that the large group velocities and small anharmonicity are the main reasons for its high lattice thermal conductivity. We also calculate the lattice thermal conductivity of monolayer WSi2N4, which is only a little smaller than that of MoSi2N4. Our findings suggest that monolayer MoSi2N4 and WSi2N4 are potential 2D materials for thermal transport in future nano-electronic devices.
Non uniqueness of non runaway solutions of Abraham—Lorentz—Dirac equation in an external laser pulse
Authors: Carati A , Stroppi M
Published: February 2021

In the paper (Carati et al 1995 Non Linearity
8 65-79) it was shown that, for motions on a line under the action of a potential barrier, the third-order Abraham–Lorentz–Dirac equation presents the phenomenon of non uniqueness of non runaway solutions. Namely, at least for a sufficiently steep barrier, the physical solutions of the equation are not determined by the ‘mechanical state’ of position and velocity, and knowledge of the initial acceleration too is required. Due to recent experiments, both in course and planned, on the interactions between strong laser pulses and ultra relativistic electrons, it becomes interesting to establish whether such a non uniqueness phenomenon extends to the latter case, and for which ranges of the parameters. In the present work we will consider just the simplest model, i.e., the case of an electromagnetic plane wave, and moreover the Abraham–Lorentz–Dirac equation will be dealt with in the non relativistic approximation. The result we found is that the non uniqueness phenomenon occurs if, at a given frequency of the incoming wave, the field intensity is sufficiently large. An analytic estimate of such a threshold is also given. At the moment it is unclear whether such a phenomenon applies also in the full relativistic case, which is the one of physical interest.
Inhibition of Na+/H+ exchanger modulates microglial activation and scar formation following microelectrode implantation
Authors: Dubaniewicz Mitchell , Eles James R , Lam Stephanie , Song Shanshan , Cambi Franca , Sun Dandan , Wellman Steven M , Kozai Takashi D Y
Published: February 2021

Objective. Intracortical microelectrodes are an important tool for neuroscience research and have great potential for clinical use. However, the use of microelectrode arrays to treat neurological disorders and control prosthetics is limited by biological challenges such as glial scarring, which can impair chronic recording performance. Microglia activation is an early and prominent contributor to glial scarring. After insertion of an intracortical microelectrode, nearby microglia transition into a state of activation, migrate, and encapsulate the device. Na+/H+ exchanger isoform-1 (NHE-1) is involved in various microglial functions, including their polarity and motility, and has been implicated in pro-inflammatory responses to tissue injury. HOE-642 (cariporide) is an inhibitor of NHE-1 and has been shown to depress microglial activation and inflammatory response in brain injury models. Approach. In this study, the effects of HOE-642 treatment on microglial interactions to intracortical microelectrodes was evaluated using two-photon microscopy in vivo. Main results. The rate at which microglia processes and soma migrate in response to electrode implantation was unaffected by HOE-642 administration. However, HOE-642 administration effectively reduced the radius of microglia activation at 72 h post-implantation from 222.2 µm to 177.9 µm. Furthermore, treatment with HOE-642 significantly reduced microglial encapsulation of implanted devices at 5 h post-insertion from 50.7 ± 6.0% to 8.9 ± 6.1%, which suggests an NHE-1-specific mechanism mediating microglia reactivity and gliosis during implantation injury. Significance. This study implicates NHE-1 as a potential target of interest in microglial reactivity and HOE-642 as a potential treatment to attenuate the glial response and scar formation around implanted intracortical microelectrodes.
Potential-based three-dimensional route choice model for pedestrian evacuation on terraced stands
Authors: Liu Ying , Du Jiawang , Sun Cheng
Published: February 2021

This study proposes a potential-based three-dimensional cellular automata model to describe the route choice behavior of pedestrians while evacuating terraced stands. The model takes into account the pedestrians’ states of sitting, standing, and moving, and the possible transitions on terraced stands. The proposed potential field algorithm reflects the influence on route choice behavior of heterogeneous heights, route distance, pedestrian congestion, and route capacity. Three parameters related to the pedestrians’ behaviors in the spaces with heterogeneous heights are then analyzed to demonstrate the ability of the model to reproduce pedestrian route choice behaviors on terraced stands. Finally, empirical data observed in a terraced stand of a stadium are applied for further validation. The results show that the proposed model performs consistently well with the observed data.
Digital sorting of laser beams by radial number: degenerate and non-degenerate states
Authors: Volyar A V , Bretsko M V , Akimova Ya E , Egorov Yu A
Published: February 2021

We have created and tested a computer sorting method of Laguerre-Gauss (LG) radial modes with permanent topological charge arising from the perturbation of both single LG beams and their composition using a diaphragm with different radius R. The method based on computer analysis of the intensity moments. We considered two types of perturbed beams: single LG beam and complex LG beams with different radial number included in an integral array. The diaphragm acts on LG beam in such a way that when the radius of the diaphragm decreases, a set of secondary LG modes with different radial indices, which are characterized by different mode spectra, arise. Reconstructed spectrum using digital processing allows one to reconstruct the real LG modes and calculate the measure of uncertainty arising under the action of a disturbance, using the concept of information entropy. The calculations performed showed that the correlation degree of the measured disturbed beams is about 0.94. It was also found that the perturbation of a complex beam leads to the appearance of a degenerate spectrum in amplitudes, since one spectral line corresponds to a whole set of modes with different radial indices. To detect the spectrum, it was required to know M keys, which are the spectra of the amplitudes of nondegenerate perturbed beams in our experiment, degree of correlation was also 0.94.
Results of the study of the possibility of replacing the Gia GemSet, designed for evaluating the color of precious stones, with digital simulators for automated control systems
Authors: Kushkoeva A S , Chertov A N , Gorbunova E V , Veselov S V
Published: February 2021

Currently, the quality of precious stones is assessed by the organoleptic method. To identify their color experts use a set of Gia GemSet imitators made of transparent acrylic plastic-a polymer with a high refractive index, and with its own GIA color space. The authors conducted research on the optical characteristics of the GIA GemSet set in order to study the possibility of replacing physical standards with digital simulators for automated control systems. The research was carried out using two methods: spectral and technical vision. Spectral measurements were performed using a USB4000 fiber-optic spectrometer. To determine the color characteristics of digital images, we used a proprietary hardware and software package. Based on the research results, a color body of the GIA GemSet for the case of a standard D65 source is constructed, which gives a visual representation of the characteristics of the set. The correspondence between the color coordinates of the samples obtained by the two methods is established, which confirms the possibility of automation of color of precious stones evaluation process.
Photonic crystal structures based on submicron particles of polymethyl methacrylate
Authors: Nemtsev I V , Shabanova O V , Shestakov N P , Ivanenko A A , Cherepakhin A V , Ya Zyryanov V
Published: February 2021

Morphological parameters, reflection spectra, IR absorption spectra, and glass transition temperatures of submicron-sized spheres of poly(methyl methacrylate) (PMMA) formed in a water-acetone dispersion medium were studied in comparison with similar spheres obtained in distilled water. Dependence of a shrinkage degree of the submicrospheres on the concentration of acetone in water is studied. Features of the formation of periodic structures based on the water-acetone dispersions of PMMA in four different ways are considered. 2D (photonic crystal films) and 3D (artificial and inverse opals) resonance structures were obtained.
Digital model to optimize the rotor assembly for aircraft engine compressor models
Authors: Bolotov M A , Pechenin V A , Yu Pechenina E , Pronichev N D
Published: February 2021

The article focuses on the problems of knowledge-intensive products assembly quality in aircraft engine industry. A mathematical model has been proposed to determine optimal conditions for mating assembly units of a low-pressure compressor (LPC) rotor of an aircraft engine. Parameters optimized include relative angular positions of parts in the rotor. Three optimization criteria have been considered: assembly geometry; imbalance value and integral criterion combining both above criteria. The model has been implemented in the MATLAB system. The calculations have been made using actual part models created based on measurements of the LPC parts geometry. The best optimization criterion has been selected.
Decomposition of a System of Equations of Motion of a Spacecraft with a Considerable Asymmetry in a Rarefied Atmosphere
Authors: Lyubimov V V
Published: February 2021

We consider a system of equations simulating an uncontrolled descent of a spacecraft in a low-density atmosphere. The spacecraft is a solid body with a shape close to a solid of revolution. An important structural feature of the spacecraft is the presence of considerable geometric and aerodynamic asymmetry in its design. It should be noted that the initial system of equations of motion for the spacecraft is essentially nonlinear. In order to enable an effective asymptotic analysis of the evolution of motion of the spacecraft, it is necessary to decompose the initial system of equations of motion of the spacecraft. The aim of this study is to decompose the system of equations of motion of the spacecraft into two subsystems: slow-motion subsystem and fast-motion subsystem. The method of integral manifolds makes it possible to lower the order of the initial system of equations. The resulting slow subsystem can be represented in the form of a single-frequency system of equations with several slow variables. An important applied result of the study is the fact that the subsequent analysis of the evolution of slow variables in a slow subsystem can be performed using known asymptotic methods.
The optimal aircraft gas turbine engine control in low gas mode in the conditions of external additive noise
Authors: Novikova S V , Tutubalin P I , Snegurenko A P , Yakhina R R
Published: February 2021

The article is devoted to algorithm development to select an optimal control law of a gas turbine engine in the conditions of external additive noise and incomplete information regarding the values of control parameters. A step by-step algorithm for problem solving is given. The effectiveness of the algorithm is proved by numerical experiments.
Mathematical modeling of mass-heat transfer processes on the grain of a catalytic cracking catalyst
Authors: Uzyanbayev R M , Yusupova R R , Gizzatova E R
Published: February 2021

One of the most important processes ensuring deep oil refining both abroad and in Russia is the catalytic cracking process. This is the largest tonnage process of secondary oil refining and takes the second place in terms of the volume of processed raw materials after its primary distillation. The study of processes on the catalyst grain is necessary to create effective catalytic systems. The calculations of the chemical process on the catalyst grain are carried out on the basis of solving the equations of the mass balances of components and heat.
Synthesis of the optimal control law for the reorientation of a nanosatellite using the procedure of analytical construction of optimal regulators
Authors: Sinitsin L I , Kramlikh A V
Published: February 2021

The method is described in the article and an algorithm for the synthesis of the optimal control law for the reorientation of the nanosatellite using the procedure of analytical construction of optimal regulators is proposed. The algorithm provides a search of control for reorienting the nanosatellite along a phase trajectory close to the nominal one, subject to restrictions on the magnitude of the control torque. The nominal trajectory is divided into local sections, on each of which the required control is calculated.
3D computer-aided simulation of SHS macrokinetics in the Ni-Al porous medium with the closest packing of “mesocells”
Authors: Jordan V I , Shmakov I A , Grigoryevskaya A A
Published: February 2021

The paper discusses the methodological features of the procedure for simulation the SHS process in the “etalon” model structure of the closest packing of the so-called mesocells in the form of balls of the same radius. In the center of the mesocell there is a spherical Ni particle (radius R
Ni = 30 μm), around which aluminum particles of radius R
Al = 10 μm are contained in a spherical interlayer with a thickness of 20 μm. The etalon structure is formed by a program that takes into account the distribution of mesocells in the structure of the closest packing (alternating flat layers with square symmetry). The software has implemented the procedure for preparing the “calculation area” in the form of a three-dimensional grid of nodal points (3D Cartesian calculation grid with the same step h= 1 μm along the x, y, z coordinates), for which a 3D data structure Points[i][k][l] with several record fields was created. The record fields of the structure Points[i][k][l] are the following: T- temperature, η - depth of chemical conversion, type - type of material and etc. A technique for numerical solution of the heat conduction equation using an implicit scheme of bicyclic splitting based on the symmetric Krank-Nicholson scheme is implemented. Together with the bicyclic splitting scheme, a procedure is implemented for numerically solving the diffusion kinetics equation in mesocells. For computational speedup, the parallelization schemes of cycles are used, which determine the main time costs for performing “runs (sweep)” in the computing schemes. As a result of 3D simulation of SHS macrokinetics, sets of temperature profiles and time-varying relative radii (external boundaries) of intermetallic phase layers in mesocells are given.
Modification and training of the “ant algorithm” for planning swarm operations of moving object
Authors: Mostovoi Y A , Berdnikov V A
Published: February 2021

A swarm of mobile robots, as a system of relatively simple interconnected controlled objects, performs a common task simultaneously and in a distributed manner. When planning swarm operations associated with the creation in the service area through the frontal band of the zones of operation of the target equipment there is a need to consider the possibility of its operational regrouping, since at the time of planning the exact purpose of the swarm operation has not yet been determined, or is a secret, or is determined by a number of random circumstances. The execution of the swarm operation is advisable to carry out in two phases. The first phase starts even before the resolution of these uncertainties by creating a basic random network with a relatively small concentration of robots. In the second phase, after resolving the uncertainty, a programmable percolation route is formed by local rearrangement of the swarm objects, which provides a predetermined coverage of the target equipment of the robots with a certain service zone. A modified ant algorithm with evolutionary learning is considered in order to quickly solve the swarm problem of two-phase operation. In this case, you can significantly reduce the time for the operation.
Asymptotic stress fields near the crack tip in perfect plastic materials under mixed mode loading (plane strain conditions)
Authors: Stepanova L V
Published: February 2021

In the paper the asymptotic stress fields in the vicinity of the crack tip in perfectly plastic Mises materials under mixed mode loading for the full range of the mode mixities are presented. This objective is engendered by the necessity of considering all the values of the mixity parameter for the full range of the mode mixities for plane strain conditions to grasp stress tensor components behaviour in the vicinity of the crack tip as the mixity parameter is changing from 0 to 1. To gain a better understanding of the stress distributions all values of the mixity parameter to within 0.1 were considered and analysed. The asymptotic solution to the statically determinate problem is obtained by the eigenfunction expansion method. Steady-state stress distributions for the full range of the mode mixities are found. The type of the mixed mode loading is controlled by the mixity parameter changing from zero for pure mode II loading to 1 for pure mode I loading. It is shown that the analytical solution is described by different relations in different sectors, the value of which is changing from 7 sectors to 5 sectors. At loadings close to pure mode II, seven sectors determine the solution whereas six and five sectors define the solution for the mixity parameter higher 0.33 and less than 0.89 and higher 0.89 respectively for plane strain conditions. The number of sectors depends on the mixity parameter. The angular stress distributions are not fully continuous and radial stresses are discontinuous for some values of the mixity parameter. It is interesting to note that the characteristic feature of the asymptotic solution obtained is the presence of a segment of values of the mixity parameter for which the solution does not depend on the mixity parameter (the solution does not depend on the mixity parameter for the mixity parameter from 0.89 to 1 and the solution coincides with the solution for mode I crack in perfect plastic materials for plane strain conditions). Thus, the salient point of the study is that the asymptotic solution is described by the same formulae for all values of the mixity parameter from 0.89 to 1 for plane strain.
Modeling of onboard systems operation of small satellites based on general logical-probabilistic method
Authors: Salmin V V , Tkachenko I S , Volgin S S , Ivanushkin M A
Published: February 2021

An approach for simulating the operation of onboard systems of small satellites has been developed. The purpose of the technique is to simulate all possible combinations of malfunctions in the onboard systems of the small satellite, leading to the occurrence of abnormal situations during their operation. As a result of using the technique, a list of emergency situations is created, which is later used to create programs for complex testing of small satellite on-board equipment at the ground testing stage. The use of the technique leads to a reduction in time for the preparation of tests, provides support in making decisions on the management of the small satellites and reduces the response time to emergency situations that arise during operation.
Determination of the main design parameters of cost-effective remote sensing satellite systems at the stage of preliminary design
Authors: Salmin V V , Kurenkov V I , Safronov S L , Tkachenko I S , Yakischik A A , Ivanushkin M A , Volgin S S , Krestina A V
Published: February 2021

This article surveys approaches to the selection of design parameters and modelling the functioning of the remote sensing satellite systems, taking into account the requirements and restrictions on customer resources. The objective of this research is to increase the efficiency of the use of space systems to solve urgent tasks of monitoring the earth’s surface. Firstly, an analysis of the requirements for space imagery materials and consumer information support was carried out, secondly, mathematical models of remote sensing equipment and onboard systems of small spacecraft were developed, and finally, a database with the technical characteristics of the onboard systems and remote sensing equipment of spacecraft, launch vehicles and ground-based reception and processing information facilities was created. As a result, software to determine main design parameters and modelling the functioning of cost-effective remote sensing satellite systems was developed.
Efficiency of different separation elements for removal of fine particles from gas
Authors: Zinurov V E , Dubkova N Z , Popkova O S , Dmitrieva O S
Published: February 2021

A paper deals with the urgent problem of studying the separation process of gas flow from fine-dispersed particles. A device developed to intensify gas flow separation from fine-dispersed particles. The principle of operation of the device is given. The effect of the shape of separation elements, gas flow velocity, as well as size and density of particles on device efficiency, has been investigated. As a result of the study, the maximum efficiency of gas flow separation (on average 85%) is achieved at a gas velocity of 8 m/s. Moreover, the separation increases when the density and diameter of the particles begin to grow. The double-T shape of separation elements was demonstrated as the most effective type of geometry.
Naimark complements in the building of simplices
Authors: Novikov S Ya , Fedina M E
Published: February 2021

We define frames for a finite dimensional Hilbert space ℍ as the complete systems in ℍ. An equiangular tight frame (ETF) is an equal norm tight frame with the same sharp angles between the vectors. A regular simplex is a special type of ETF in which the number of vectors is one more than the dimension of the space they span. A detailed and independent from other sources presentation of recent results by M. Fickus, J. Jasper, E. J. King and D. G. Mixon is given, in which a lower bound for the spark of the system of equal norm vectors is obtained using the restricted isometry property. The existence of the regular s-simplices for an arbitrary positive integer s is proved using Naimark complement. A review of recent results towards resolving the known Paulsen problem is given.
On small perturbations of Markov cyber threat models
Authors: Magazev A A , Tsyrulnik V F
Published: February 2021

In this work, we consider Markov chain-based stochastic modeling of cyber threats acting on computer systems. In the framework of this approach, computer systems are considered as systems with failures and recoveries by analogy with technical system models in reliability theory. Under the assumption that the cyber threats are independent random events, we derive the explicit analytic formulas for the state probabilities of the corresponding Markov chain and the mean time to security failure (MTSF). Then we investigate the case of dependent cyber threats and derive the approximate expressions for the state probabilities and MTSF within the framework of the first-order perturbation theory. As an illustration of our results, we consider a few simple examples.
Decentralized square-root information Kalman filtering based on J-orthogonal transformations
Authors: Tsyganov A V , Tsyganova Yu V
Published: February 2021

The paper addresses the problem of decentralization of the measurement data processing based on matrix J-orthogonal transformations in the square-root information Kalman filter. J-orthogonal transformations are applied in a decentralized filter at the stage of communication and assimilation. The results of numerical experiments confirm the efficiency of the proposed solution. The developed algorithm can be used for measurement data processing in decentralized distributed computing networks.
Algorithm for detecting a change in the motion mode of an object moving along a complex trajectory
Authors: Golubkov A V , Tsyganov A V , Petrishchev I O
Published: February 2021

The present paper solves the problem of quick detection of a change in the motion mode of an object moving along a complex trajectory. The process of the object movement is described by a hybrid stochastic model. To solve the problem, a sequential probability ratio criterion is applied. A distinctive feature of the proposed algorithm is the ability to make decisions on a limited set of values of the likelihood ratio function. The results of numerical experiments confirm the efficiency of the developed algorithm.
Approximate analytical solution of the Graetz problem
Authors: Eremin A V
Published: February 2021

The study on velocity and temperature distribution in fluid flows is important both for the theory and practical applications. The design of efficient heat-exchange equipment, the development of heat and thermomechanical modes of product treatment, the determination of heat losses in the pipeline systems include the need to determine the velocity and temperature fields in fluid flows. The key aspects of the method have been considered with help of using the example of solving the Graetz problem for parallel and cylindrical channels.

It is shown that finding the solution to a partial differential equation with respect to the temperature function can be reduced to integrating an ordinary differential equation with respect to the new unknown function q(η) which is the law of temperature change in the center of the channel. The combined use of the heat balance integral method and additional boundary characteristics made it possible to obtain a simple in form analytical solution to the problem under consideration. It is noted that the accuracy of the solutions obtained depends on the number of approximations used, i.e. the number of terms of the approximating series.

When using only one term, i.e. already in the first approximation, the relative error of the method is not more than 8 percent in the range of the longitudinal coordinate change 0.1 ≤ η < ∞ and decreases to 4 percent in the second approximation. The analytical form of the solutions obtained provides analyzing the isotherms fields, calculating the average temperature, the Nusselt number, etc.
Numerical implementation of biological kinetics multi-species model in the Azov Sea
Authors: Sukhinov A I , Nikitina A V , Filina A A , Leontyev A L
Published: February 2021

Paper covers the research of biological kinetics processes based on a multi-species model of plankton and fish interaction of the Azov Sea at low and high size considering the V erhulst and Allee effects, competition for resources, taxis, catching, spatial distribution of biogenic matter and detritus. Discrete analogue of developed model problem of water ecology, included in a software complex, were calculated using schemes of increased order of accuracy considering the partial filling of computational cells. The system of grid equations of large dimension, arising at discretization, has been solved on the basis of a two-layer variational type method – the minimum corrections method having the maximum convergence rate. Effective parallel algorithms were developed for numerical implementation of biological kinetics problem and oriented on multiprocessor computer system and NVIDIA Tesla K80 graphics accelerator with the data storage format modification of. Due to it, the reproduction processes of biogeocenose populations have been analysed in real and accelerated time.
XXIst Century Perspectives on the Micro & Macro Worlds
Authors: Mimouni J
Published: February 2021

We present a broad perspective on our (Early) XXIth century understanding of both the macro and micro worlds, and whether the dream embodied in the symbolism of Glashow’s snake (Ouroboro) has been implemented to some degree or recessed away. Do we have a unified vision of the world at those extreme scales? What about the status of that «21st century» theory «that fell accidentally into the 20th century.” aka superstrings to quote E.Witten, and which is the «ideological» cement of very powerful aspiring-to-be paradigms like Cosmic Inflation, Multiverses, extra dimensions (ED) … as well as the inspiration of most pre-Big Bang theories. We will discuss along the way the fine tuning curse, the Cosmic Inflation and Multiverse’s Pandora box, and other big mysteries perhaps of our own making, and propose that in our search for «truth», and to keep our sanity in the actual jungle of bold «new ideas» and puzzles, we be guided by the voice of reason which goes by the unpretentious name of under-determinacy of theories.
Lessons from supersymmetric black holes
Authors: Messamah I , Van Den Bleeken D
Published: February 2021

This paper studies the D4-D0 system in light of black hole puzzles. The properties of its microstates, that live in the associated quiver quantum mechanics [1, 2], are discussed. It is shown that the pure Higgs states of these quivers satisfy the needed properties to be (part of) the microstates of a single centered D4-D0 black hole.
Interacting Chaplygin gas cosmology
Authors: Bensaid A , Bouamrane R
Published: February 2021

In this paper, we study in FRW universe the interaction between the viscous Chaplygin gas and the dark energy in the modified gravity theory F(R,T), where T and R are the trace of the energy-momentum tensor and is the Ricci scalar respectively. In this model, the universe is dominated by both components Chaplygin gas and dark energy. We discuss the effect of the bulk viscosity on the dark energy state parameter, this study was carried for two interactions after obtaining the modified Friedmann equations. Finally, we found that both interaction models lead to quintessence phase of the dark energy.
A general study of charged particles dynamics near magnetic planets
Authors: Leghmouche A , Mebarki N
Published: February 2021

A general study of the Störmer problem is carried taking into account the combined effect of the dipolar and quadrupolar magnetic terms as well as the gauss coefficients for Earth and Saturn. The resulted trajectories as well as the critical states for various kinds of charged dust grains are studied.
Study of the effects of the curvature term in the density of states on some physical quantities characterizing the deconfining phase transition to a color-singlet QGP
Authors: El Djoudi A Ait , Djida R , Mezouar K , Abbad N
Published: February 2021

In the present work, we study the effect of including the curvature term, in addition to the volume term, in the density of states used in the calculation of the projected color-singlet partition function of the Quark-Gluon Plasma (QGP), on some features characterizing the phase transition to this new phase of matter. By investigating the behavior of some physical quantities well describing the mixed system with temperature for varying volume, we especially examine the behavior with volume of the shift of the effective transition temperature in a finite volume from the true one, to determine the corresponding scaling exponent. We compare the present results to those obtained in our previous works, where we have used a color-singlet QGP partition function derived with a density of states containing the volume term only.
Dark matter nature at electron-positron colliders: scalar or fermionic?
Authors: Baouche N. , Ahriche A.
Published: February 2021

In this work, we investigated the possibility of identifying DM nature, at the future electron-positron colliders such as the International Linear Collider (ILC) and Compact Linear Collider (CLIC), at

s

=

500

GeV

and 1 TeV, using the final state

b

b
¯

+

E

T

. For this purpose, we consider two models in which DM could be either a real scalar or a heavy right-handed neutrino (RHN). So we considered two parameter values sets for both models, and we defined and investigated the different recent experimental constraints. After that we define a set of kinematical cuts that suppress the background, and generate different distributions that are useful in identifying the DM nature. The use of polarized beams P(e
−, e
+) = [+0.8,−0.3] at the ILC makes the signal detection easier and the DM identification more clear, where the statistical significance gets enhanced by twice (five times) for scalar (fermionic) DM.
Path integral formulation for position–time-dependent mass systems
Authors: Berrabah Badri , Bentag Baya
Published: February 2021

The problem of position-time dependent mass with general time-dependent potential is treated in the framework of the phase space path integral approach. By means of an appropriate point canonical transformation, the problem is converted into that relative to a constant mass with stationary potential. Particular examples are also considered.
Improvements for NLP Models by Considering Language Differences
Authors: Zhang Ruiqi
Published: February 2021

Aspect extraction has been playing a critical role in opinion mining of product reviews. Most of the existing works tackling various Natural Language Processing tasks focus on English corpus and barely talked about the effect of language differences when apply the algorithm to other languages. Based on a previous aspect extraction neural model and its application to text data in Chinese, this paper analyzed possible reasons and proposed plausible approaches to address the importance of handling language differences in Natural Language Processing tasks. By bringing the importance of adaptiveness of language models to attention, future NLP research work might produce more robust and comprehensive work regardless of the impact of language differences.
Research Progress of Virtual Reality Modeling Based on Three-Dimensional Reconstruction Technology
Authors: Long Wei , Wang Tianyu , Lu Yujie , Xu Huang , Gao Qiang , Jiang Linhua
Published: February 2021

The limitations of virtual reality (VR) modeling and construction is one of the key issues in the recent research. An accurate model constructed based on real-world scenes is time and resource consuming. The three-dimensional (3D) reconstruction technology can efficiently construct models based on real-world objects, which is ideal for high-speed VR modeling system. This paper introduces the modeling examples based on 3D reconstruction in VR devices, compares the advantages/disadvantages between various reconstruction methods and comprehensively introduces the combination of the different methods. The summary and future development trend is also discussed at the end.
Theoretical Framework of Energy Internet Demand Forecasting Based on Internal and External Information Fusion
Authors: Jiang Shigong , Yang Weihong , Wu Zhili , Cao Yuwei , Zeng Ming , Shi Pengjia
Published: February 2021

Due to the limited information sources, the existing energy demand forecasting models cannot fully, truly and accurately reflect the nature of the trend change of Energy Internet demand. To solve this problem, this paper establishes a theoretical framework of Energy Internet demand forecasting based on internal and external information fusion from the perspective of information sources. The framework summarizes the data characteristics of energy internet and divides the data information into internal information and external information. According to the attribute characteristics of data information, the forecasting information is divided into data layer, feature layer and decision layer. Finally, a combined forecasting model is established for data at different levels for data forecasting. The framework uses multi-source information fusion prediction theory to fuse the internal and external prediction information of energy Internet in different situations, which increases the amount of information of the prediction model.