bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of hub inclination angle on internal and external characteristics of centrifugal pump impellers
Authors: Kuang Renfei , Zhang Zhiming , Wang Shaolong , Chen Xiaoping
Published: February 2021

The flow characteristics at a centrifugal pump impeller are significantly affected by the hub inclination angle (HIA). The large eddy simulation turbulence model is employed to simulate the centrifugal pump impeller internal flow at two HIA values under design (1.0 Qd) and off-design (0.55 Qd) conditions. The reliability of the simulation results is verified by comparing the results at a 0° impeller HIA and experimental data. The results show that an increase in HIA has a positive effect on the head of the centrifugal pump impeller, which exhibited a 5% relative deviation between HIA values of 0° and 40°. Under design conditions, there is a good and similar impeller internal flow at the two HIA values. Under off-design conditions, the relative velocity of the 40° impeller HIA channel inlet is 11.7% higher than that of the 0° impeller HIA, which reduces the flow attack angle and effectively suppresses stall. Moreover, for the 0° impeller HIA, fluctuation caused by the stall cells on the blade suction surface is observed, whereas such a phenomenon is not observed for the 40° impeller HIA.
Theoretical investigation on bisarylselanylbenzo-2,1,3-selenadiazoles as potential photosensitizers in photodynamic therapy
Authors: Mazzone Gloria , De Simone Bruna Clara , Marino Tiziana , Russo Nino
Published: February 2021

Density functional theory and time-dependent (TDDFT) calculations were carried out for recently reported bisarylselanylbenzo-2,1,3-selenadiazoles derivatives capable of producing singlet oxygen (1O2) under UV–Vis irradiation. Conformational behaviors, excitation energies, singlet–triplet energy gaps, and spin–orbit coupling constants were evaluated. The conformational analysis evidences that two different conformers have to be taken into consideration to completely describe the photophysical properties of this class of molecules. TDDFT results show that these compounds, though possessing absorption wavelengths that fall in the violet region, are characterized by singlet–triplet energy gaps greater than the energy required to excite the molecular oxygen, thus being able to produce the cytotoxic species, spin-orbit coupling constants large enough to ensure efficient singlet–triplet intersystem spin crossing, and even the highly reactive superoxide anion O2•(−) by autoionization and subsequent electron transfer to molecular oxygen in its ground state.
Fiber-optic silicon Fabry–Perot interferometric bolometer with improved detection limit for magnetic confinement fusion
Authors: Uddin Nezam , Sheng Qiwen , Mitul Abu Farzan , Lee Seungsup , Reinke Matthew L. , Donovan David , Shafer Morgan , Han Ming
Published: February 2021

Fiber-optic bolometers (FOBs) intended for plasma radiation measurement in magnetically confined fusion have been previously developed using a silicon pillar that functions as both a Fabry–Perot interferometer (FPI) for temperature measurement and an absorber for the radiation. We report an FOB design that can significantly improve the detection sensitivity over earlier designs by engineering the absorber of the FOB. Our design uses the fact that, compared with a silicon pillar, a gold film with the same x-ray absorption thickness will show a much higher temperature rise from a given power density of the radiation. Therefore, the responsivity of an FOB can be improved by attaching a large gold disk to the silicon FPI as the absorber. We have developed a fabrication method for FOBs of such design and obtained an FOB with a 4-µm-thick, 0.6-mm-diameter gold disk attached to a 200-µm-diameter, 100-µm-thick silicon FPI. We have characterized the noise, responsivity, response time, and noise-equivalent power density (NEPD) and compared these with the earlier design where the absorber is mainly the silicon FPI itself. The experimental result suggests that the FOB with the gold disk achieves a responsivity of ∼2.8 mK/(W/m2) and a noise-equivalent-power-density of 0.13 W/m2, which are, respectively, more than nine times larger and six times smaller compared to the FOB using a previous design. Improved NEPD and good absorption over a broad frequency range will make the FOB more attractive for applications in magnetic-confinement fusion devices.
Toward 40 GHz excitation of diamond-based HBAR
Authors: Sorokin Boris P. , Asafiev Nikita O. , Kvashnin Gennady M. , Scherbakov Denis A. , Terentiev Sergey A. , Blank Vladimir D.
Published: February 2021

We have obtained an excitation of longitudinal bulk acoustic waves in a diamond-based High overtone Bulk Acoustic Resonator (HBAR) at microwave and enhanced frequency bands as EHF up to 40 GHz. As an effective piezoelectric transducer, an aluminum-scandium nitride film is employed. The frequency response of acoustic overtones excited in the HBARs with a different aperture in the 1.0 up to 40 GHz range is measured. Some peculiarities of HBAR's frequency response concerned with the thin film piezoelectric transducer are studied. It is established that the maximal magnitude of the quality factor varies near the value of about 10 000 within all the frequency bands investigated. The approximately frequency-independent Q-factor behavior can explain in terms the Landau–Rumer approximation describing the acoustic attenuation in a diamond. An estimation of the HBAR's quality parameter as Q × f ≈ 4 × 1014 Hz at 40 GHz is obtained. In our opinion, that value exceeds all known data among the given devices. The results obtained will be helpful in the development of microwave and EHF acoustic resonators as well as highly sensitive acoustic sensors. The development of the EHF band opens up the possibility of obtaining acoustic waves of submicrometer and nanometer scales (in various media) and implementing acoustic studies of micro- and nanoobjects.
Theory of dissipation pathways in open quantum systems
Authors: Kim Chang Woo , Franco Ignacio
Published: February 2021

We introduce a simple and effective method to decompose the energy dissipation in the dynamics of open quantum systems into contributions due to individual bath components. The method is based on a vibronic extension of the Förster resonance energy transfer theory that enables quantifying the energy dissipated by specific bath degrees of freedom. Its accuracy is determined by benchmarking against mixed quantum–classical simulations that reveal that the method provides a semi-quantitative frequency-dependent decomposition of the overall dissipation. The utility of the method is illustrated by using a model donor–acceptor pair interacting to a thermal harmonic bath with different coupling strengths. The method can be used to identify the key features of a bath that leads to energy dissipation as required to develop a deep understanding of the dynamics of open quantum systems and to engineer environments with desired dissipative features.
Range extensions and habitat use of Forrest’s mouse (
Authors: Madani G. F.
Published: February 2021

Rodent populations are dynamic, and fluctuate with environmental conditions and threatening processes, so their numbers and distributions are not spatially static. Many arid and semi-arid areas also remain poorly surveyed, limiting our understanding of species’ distributions. Fauna surveys in the western division of New South Wales recorded new localities for a previously undetected species – Forrest’s mouse (Leggadina forresti) – in Culgoa and Ledknapper National Parks, equating to an easterly range extension of 430 km. Forrest’s mouse appears to persist in riverine plains, and this habitat may serve as important residual intact habitat within the rangelands of NSW. As a native and vulnerable rodent species that occurs at low density, has low trapping success and occurs in an area that is poorly sampled outside of the reserve system, it should be the target of future survey and conservation efforts within the region.
Diet, feeding behaviour and echidna beaks: a review of functional relationships within the tachyglossids
Authors: Nicol Stewart C.
Published: February 2021

Echidnas are commonly known as ‘spiny ant-eaters’, but long-beaked echidnas (Zaglossus spp.) do not eat ants, whereas short-beaked echidnas (Tachyglossus aculeatus) eat other invertebrates as well as ants. The differences in skull morphology between short- and long-beaked echidnas are related to the differences in their diets, and I tested the hypothesis that there would be differences in beak length of short-beaked echidnas from populations with different diets. Published data on diet from echidnas from different parts of Australia show that echidnas from arid and semi-arid areas (subspecies acanthion) and Kangaroo Island (subspecies multiaculeatus) principally eat ants and termites, whereas the main dietary items of echidnas from south-eastern Australia (subspecies aculeatus) and Tasmania (subspecies setosus) are ants and scarab larvae. Using museum specimens and photographs I measured skull dimensions on echidnas from different parts of Australia: acanthion and multiaculeatus have narrower skulls and shorter beaks than aculeatus and setosus, with setosus being the only Australian subspecies where beak length exceeds cranium length. Australian short-beaked echidnas fall into two groups: aculeatus and setosus from the wetter east and south-east, which eat ant and scarab larvae, and the arid and semi-arid zone acanthion and multiaculeatus, with shorter, narrower skulls, and which eat ants and termites.
Operando
characterization of conductive filaments during resistive switching in Mott VO
2
Authors: Cheng Shaobo , Lee Min-Han , Li Xing , Fratino Lorenzo , Tesler Federico , Han Myung-Geun , del Valle Javier , Dynes R. C. , Rozenberg Marcelo J. , Schuller Ivan K. , Zhu Yimei
Published: February 2021

Significance

To perform hardware-based neuromorphic computing, novel materials exhibiting a wide variety of electronic properties are currently being explored. VO
2
is well known to exhibit an insulator-to-metal transition as well as volatile resistive switching. Many questions regarding the basic mechanism of the nonvolatile switching in this material are unanswered. In this work, the formation and relaxation of conductive filaments through nonvolatile resistive switching in VO
2
devices have been realized. The V
5
O
9
Magnéli phase conductive filament has been identified. Our results demonstrate that both resistive switching behaviors can be achieved in a single material, crucial for future technology like resistive switching memories or neuromorphic logic.
Heritability of individualized cortical network topography
Authors: Anderson Kevin M. , Ge Tian , Kong Ru , Patrick Lauren M. , Spreng R. Nathan , Sabuncu Mert R. , Yeo B. T. Thomas , Holmes Avram J.
Published: February 2021

Significance

The widespread use of population-average cortical parcellations has provided important insights into broad properties of human brain organization. However, the size, location, and spatial arrangement of regions comprising functional brain networks can vary substantially across individuals. Here, we demonstrate considerable heritability in both the size and spatial organization of individual-specific network topography across cortex. Genetic factors had a regionally variable influence on brain organization, such that heritability in network size, but not topography, was greater in unimodal relative to heteromodal cortices. These data suggest individual-specific network parcellations may provide an avenue to understand the genetic basis of variation in human cognition and behavior.
Sex selection techniques and their implications
Authors: Naniwa Yousuke , Uchiyama Kyoko
Published: February 2021

Sex selection techniques provide economic benefits to dairy and beef herd management. Therefore, the development of such techniques has attracted the attention of reproductive biologists. There have been numerous studies concerning the development of sex selection techniques. As the sex of the offspring is determined by certain chromosomes, namely the X and Y chromosomes in mammals, most studies have focused on sperm sexing, attempting to separate the X and Y chromosome-bearing sperm based on differences in deoxyribonucleic acid (DNA) content, head size/volume, motility, and immunological specificity. However, most of these methods have failed to show reproducibility. Only the flow cytometric method has been confirmed to be accurate and reliable thus far. More than three decades have passed since this technique was first developed. The sexed semen produced with the method is currently commercialized and widely used for artificial insemination (AI) in cattle around the world. Recently, however, another technique based on differences in DNA contents using a fluidics device was developed by a commercial company. Studies focused on immunological approaches and the modification of sperm motility have also described the successful separation of the two types of sperm. Therefore, the present review evaluated the available sex selection techniques and their implications.
Exploring the Case: Panama’s Camino Real, a Historic Walking Trail
Authors: Ward-Perkins David
Published: February 2021

Introduction

In Central America, as this case study relates, there has been a recent rediscovery of the ancient trade routes and military roads: the Caminos Reales or Royal Routes. The Camino Real of Panama that runs from the Atlantic to the Pacific coast is an example of such a trade route. Once busy, it was made obsolete by the opening of the Canal and the building of the modern roads that now serve the nation’s businesses. What is the benefit, therefore, of restoring the Camino Real as a sustainable tourism project?

By exploring the case of the Camino Real, a researcher or student can better apprehend the tourism value of heritage routes.
The MBTA pipeline for detecting compact binary coalescences in the third LIGO–Virgo observing run
Authors: Aubin F , Brighenti F , Chierici R , Estevez D , Greco G , Guidi G M , Juste V , Marion F , Mours B , Nitoglia E , Sauter O , Sordini V
Published: February 2021

We describe the multi-band template analysis (MBTA) search for gravitational waves signals from coalescences of compact objects in the LIGO–Virgo data, at the time of the third observing run (2019–2020), both for low-latency detections and for offline analysis. Details are given on the architecture and functioning of the pipeline, including transient noise mitigation strategies, parameter space for the searched signals, detection of candidates and evaluation of a false alarm rate associated to them. The performance of the low-latency search is demonstrated based on the LIGO–Virgo third observing run, during which MBTA has contributed to 42 alerts, submitting candidates with a median latency of 36 s. The performance of the offline search is illustrated on a subset of data collected during the second LIGO–Virgo observation run in 2017, and are quantified based on injections of simulated signal events on the same data.
Inversion technique to obtain local ion temperature profiles for an axisymmetric plasma with toroidal and radial velocities
Authors: Bell Ronald E
Published: February 2021

A matrix inversion technique is derived to calculate local ion temperature from line-integrated measurements of an extended emission source in an axisymmetric plasma which exactly corrects for both toroidal velocity and radial velocity components. Local emissivity and toroidal velocity can be directly recovered from line-integrated spectroscopic measurements, but an independent measurement of the radial velocity is necessary to complete the temperature inversion. The extension of this technique to handle the radial velocity is relevant for magnetic reconnection and merging compression devices where temperature inversion from spectroscopic measurements is desired. A simulation demonstrates the effects of radial velocity on the determination of ion temperature.
Approximate Fokker–Planck–Kolmo-gorov equation analysis for asymmetric multistable energy harvesters excited by white noise
Authors: Wang Wei , Cao Junyi , Wei Zon-Han , Litak Grzegorz
Published: February 2021

Due to the broadband response characteristics at low levels of excitations, nonlinear multistable systems have garnered a great deal of attention in the area of energy harvesting. Moreover, various performance enhancement strategies of multistable harvesters have been proposed and discussed extensively for systems with perfectly symmetric potentials. However, it is very difficult or even impossible in practice to modulate a nonlinear system with completely symmetric potentials. Therefore, this paper investigates the stochastic response characteristics of asymmetric potential multistable harvesters excited by Gaussian white noise. Approximate Fokker–Planck–Kolmogorov equation for multistable harvester is provided, and solved by the method of detailed balance. Numerical simulations are carried out to characterize the probability distribution and power output of the response of the harvesters. Results indicate that the theoretical method could well predict the response probability distribution of the systems under white noise excitations. To be more specific, the probability distribution of velocity response at a given excitation level is not affected by the asymmetry of potentials, while the probability density function of displacement is very dependent on the shape of potentials. In terms of the power output, the numerical results agree well with the theoretical results. However, the error between numerical and theoretical results increases with the increase in the number of the steady states and the degree of asymmetry of the harvesters.
Modeling the formation of non-diffraction parabolic beams
Authors: Plastinina T A
Published: February 2021

In this article we perform a numerical study of the generalization of parabolic non-diffraction beams of two orders formed from an analytically given distribution of the ring spatial spectrum. The formation and propagation of non-diffraction parabolic beams are simulated using the Fourier transform and the Fresnel transform. The influence of the radius and width of the circular spatial spectrum on the non-diffraction properties of the beams, as well as the nature of the symmetry of the transverse beam patterns depending on the orders of the beam are researched.
The process of pore formation on a textured silicon substrate during electrochemical etching: 3D model
Authors: Shishkin I A , Lizunkova D A , Latukhina N V
Published: February 2021

The paper presents the results of modeling the mechanism for producing porous silicon on a textured surface. For various technological tasks, it is important to learn how to control the parameters of electrolytic etching to obtain the desired result. On 3D maps of the distribution of potential and etching currents, you can see that the vectors go around the pyramids and pointly etch certain sections of the surface. Confirmations of this can be seen in photographs of a scanning electron microscope and a scanning probe microscope. A detailed description of pore formation on textured porous silicon substrates has not yet been found in other works.
Simulation of plasmons on a metal nano-ring
Authors: Kozlova E S , Kotlyar V V
Published: February 2021

Using the finite difference time domain method, it is shown that a laser beam with a wavelength of 633 nm and circular polarization forms on the silver nano-ring with a width of 260 nm a surface plasmon polariton with a full width at half maximum of 0.25λ, and the maximum intensity of 1.873 a. u.
Computer optics software construction using multi-paradigm design
Authors: Yablokov D E , Pavelyev V S , Agafonov A N , Eremin A V
Published: February 2021

The common goal for all stages of software design is the components reusing that corresponds to the basic principles of the multi-paradigm approach considered in the article. The main aim of the article is a forming of new conceptual bounds in the software design based on the most significant features of procedural, object-oriented and generic programming paradigms. For each paradigm, an example of calculating a diffractive optical element (DOE) phase function on a given set of points is considered, and their advantages and disadvantages are evaluated. Code snippets were created using the C# language supporting several programming paradigms that allows defining algorithmic, behavioral and syntactic commonality. The multi-paradigm approach creates the ability for the implementation of different programming techniques during research in the area of computer optics.
Diffraction of quasimonochromatic light beams on multilayer inhomogeneous photopolymer holographic diffraction structures
Authors: Dudnik D I , Semkin A O , Sharangovich S N
Published: February 2021

A theoretical model of quasimonochromatic light beams diffraction by spatially inhomogeneous transmitting multilayer diffraction structures formed in a photopolymer material by a holographic method is presented in this work. This model takes into account the heterogeneity of the amplitude profile of the first harmonic of the refractive index of each layer of the multilayer structure. The model is presented using method of transfer matrixes whose components are the solutions of the coupled waves equations of partial derivates.
The technology of manufacturing metal-dielectric photonic crystals for THz and millimeter ranges by 3D printing
Authors: Agafonov A N , Reshetnikov A S , Tzibizov I A , Shakhmin A A
Published: February 2021

The article considers the possibility of using 3D printing technologies to manufacture the photonic crystal structures of THz and millimeter ranges. This approach consists of the manufacturing of a polymer photonic crystal matrix by 3D printing based on photopolymerization, followed by filling the voids of the matrix with fusible material that reflects well in the terahertz range (the Wood alloy was used).
Macro usage for analyzing of a telescopic system aberrations in ZEMAX
Authors: Kachurin Yu Yu , Kryukov A V , Kananykhin O A
Published: February 2021

The experience of optical system aberration analysis using ZEMAX software demonstrates the necessity to acquire and combine data from different text windows such as windows of Longitudinal Aberration, Ray Fan, Field Curvature and Distortion, Lateral Colour etc. This routine operation takes much time and significantly slows down the design process. Moreover, an engineer should always remember about some features of data interpretation connected with different calculation algorithms in different optical schools. It instigated us to develop a macro that forms one-window aberration summary for afocal systems with proper data interpretation according to domestic optical scientific school.
Media competence of an editor as a factor of the effective promotion of scientific journals in the international information environment
Authors: Zhilavskaya I V
Published: February 2021

The article gives insights into the concept of media competence regarding the profession of an editor of a scientific journal. Currently, the media competence is gaining the same relevance as other important competencies of publishers of scientific periodicals. The ability to find the required information quickly and efficiently, the ability to work professionally with international scientometric databases, a good understanding of the process of promoting a publication in the information environment, an ability to see if the publication corresponds to the research request and bibliographic description - all these and other skills and knowledge become crucial in organizing the work of the editorial staff of a scientific journal. At the same time, it should be recognized that the editorial staff of scientific journals acquire professional media competences directly in the process of work on the basis of their own successful or less successful experience. The country does not have a training system for such personnel, despite the fact that the challenges faced by the publishers are ambitious. These challenges require an integrated approach, including the increase of the media competence of editors of scientific journals.
70 years’ anniversary of Professor Sergei B. Odinokov
Authors: Danilov V A , Greisukh G I
Published: February 2021

This article briefly describes scientific, pedagogical and organizational achievements of Professor, Doctor of Technical Science Sergei Borisovich Odinokov.
Solution of the inverse kinetics problem for the catalytic cracking process based on a 16-component kinetic model
Authors: Mannanova G , Bikbova G , Gizzatova E
Published: February 2021

This article presents a 16-lump model of catalytic cracking of vacuum gasoil, which allows to take into account the quantity and quality of the main products of the process: gasoline, propane-propylene and butane-butylene fractions; and by-products of the process: light and heavy catalytic gasoil. To solve the direct problem of solving a system of differential equations, the Runge-Kutta method of order 4 is used, to solve the inverse problem of choosing the constants of the rate of chemical transformations, the method of direct search for minimizing the function of the sum of deviations of calculated values from experimental ones is applied. Thus, the reaction rate constants were chosen for the developed model.
Solving the problem of planning a chemical experiment based on genetic algorithms
Authors: Antipina E V , Mustafina S A , Antipin A F , Mustafina S I
Published: February 2021

The article is devoted to the task of planning an experiment in chemistry and chemical technology. The problem statement of finding the optimal ratio of the initial substances of reaction is defined. A genetic algorithm for solving this problem is proposed. The algorithm is tested on the example of the reaction of aminomethylation of thiols using tetramethylmethanediamine. The optimal initial concentrations of reagents are calculated to obtain the maximum yield of the target reaction product.
Mathematical modelling of formation process of a reinforced hole in a composite structure
Authors: Vashukov Yu A
Published: February 2021

Research of strained state of installation process of a reinforcing bushing in a hole of a part made of polymer composite material has been carried out using finite-element model. To deter-mine forces and work of installation process and influence of design factors on bushing strained state along the contour of the reinforced hole, the mathematical model has been developed.
Mathematical modeling of geothermal energy from a well extraction
Authors: Gabdrakhmanova K F , Izmailova G R , Samigullina L Z
Published: February 2021

The authors of the article examine the possibility of extracting geothermal energy to the Earth’s surface using the circulation of a heat carrier – water. For this purpose, an oil well is operated that is already suspended and is no longer used for its original purpose. A system of heat and mass transfer equations describing heat distribution in the ground around the well and in the coolant is presented. A mathematical model is developed for calculating the heat flow amount from the ground to the well distribution depending on time, thermal parameters and soil temperature; the temperature field in the near-well space calculation determining the parameters of the heating system transporting heat energy from the well to the surface is performed; the optimal period of well operation by the potential of non-reduced temperature is determined; the temperature field recovery time in the near-well space required for subsequent operation is calculated. Various well depths, geothermal gradient, and water injection rates are considered. For the first time, the relationship between ground temperature and liquid temperature in the inter-tube space and in the inner tube is considered simultaneously.
Tether system motion analysis of the various space debris’ anchor point positions
Authors: Faizullin L F , Pikalov R S
Published: February 2021

This study focuses on the dynamics of the tethered towing of the space debris. The motion of the system is reached in the force-free field and central gravitational field. A mathematical model is constructed. The space tug is modeled as a material point, the space debris as a solid body. The elastic tether connects objects to each other. In this study, we assumed that the anchor point of the tether to the space debris can be chosen arbitrarily. The aim of the work is to study the influence of the choice of the tether engagement point on the dynamics of the tug - space debris system.
Computational experiment for modeling shock-impulse technology of concrete mixtures forming
Authors: Titov S P , Thi Mong Thu Tran , Kondrashchenko V I
Published: February 2021

A mathematical model has been developed for modeling the technology of shock-impulse molding of concrete mixtures, according to the results of a computational experiment on which rational parameters of the rotor of the throwing device are determined in the form of two rotating cylinders with plates along their generatrices, intended for throwing the components of the concrete mixture onto the molded surface mechanically. A mathematical description of operation of such a device, interaction of individual particles with blades and their flight in the inter-rotor space up to the molding of the manufactured product is given. To stabilize the initial fractional composition of the aggregates, designs of rotors are proposed that provide portion capture of the concrete mixture or the use of the rubberized surface of rotors in the form of elastic tubular elements.
The change in the probability of aviation accidents “Collision of an aircraft with a bird” in accordance with of a change in the temperature cycle
Authors: Burmistrova V G , Butov A A , Volkov M A , Yavtushenko M S , Kostishko B M , Moskvicheva M G , Pchelkina Yu Z
Published: February 2021

This paper considers the possibility of predicting the most frequent aviation event “Collision of an aircraft with a bird”, depending on the seasonality near the airfield. A model for determining the probability of this event is proposed, where the “time of year” is identified by the predicted air temperature near the airfield in question and the problem of determining the accumulated probability is solved. We consider the first approximation in which events are assumed to be independent (these are complex ecological and ornithological conditions and flaws of airfield’s ornithological support). Due to the first approximation of independence, the paper provides a possible way to determine the probability of the event “Collision of an aircraft with a bird”. This method (in the form of a formula) determines the probability of intersection of events caused by hazard factors. The result of the simulation is the probability of long-term forecasting of the probability of an aviation incident due to an aircraft collision.
Mixed mode fracture in perfect plastic materials for plane stress conditions
Authors: Stepanova L V , Peksheva A A
Published: February 2021

In the study the asymptotic stress fields in the neighbourhood 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 stress 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 analyzed. 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 asymptotic solution for the mixity parameter less than 0.39 and five sectors determine the solution for other values of the mixity parameter for plane stress 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.
Further boundary conditions in heat conduction problems in multilayer structures
Authors: Trubitsyn K V , Mikheeva G V , Klebleev R M , Kurganova O Y
Published: February 2021

This paper presents an approximate analytical solution of the heat conduction problem for a two-layer plate under symmetric boundary conditions of the first kind. The solution was determined on the basis of the property of the parabolic heat transfer equation associated with an infinite velocity of heat propagation, by determining the accessory unknown function and accessory boundary conditions in the integral heat balance method.

Local coordinate systems are given in order to obtain the simplest possible coordinate system satisfying the matching conditions and boundary conditions for each separate layer. An accessory unknown function is the temperature change over time in the center of symmetry. The use of this function in the heat balance integral method allows for reduction in the solution of the initial partial differential equation to the integration of an ordinary differential equation with respect to the additional unknown function.

Further boundary conditions are defined in such a way that their satisfaction by an unknown solution is equivalent to the satisfaction of the equations at the boundary points. Studies have shown that the equation fulfillment at the boundaries leads to their fulfillment within the regions.
Application of molecular dynamics for modeling processes in microfluidic devices
Authors: Agafonov A N , Eremin A V , Milanina K I , Gavrilov V M
Published: February 2021

The article considers the possibility of using the molecular dynamics (MD) as part of multi-level models for describing processes in microfluidic devices. Much attention is paid to issues related to the use of MD to describe processes at a gas-solid interface.
Numerically stable algorithm for identification of linear dynamical systems by extended instrumental variables
Authors: Ivanov D V , Zhdanov A I
Published: February 2021

Instrumental variables are widely used to identify linear dynamical systems. The advantages of instrumental variables include low computational complexity, as well as the possibility of identification for different models of color noise. Often the method of instrumental variables leads to ill-conditioned problems, which significantly limits the application of this method. The paper proposes a solution to the problem of extended instrumental variables based on augmented normal equations. Test examples showed a high accuracy of the proposed approach.
The thermal conductivity Modeling taking in single crystals into account the anisotropy of their properties
Authors: Kh Badamshin I
Published: February 2021

For new materials, information on the thermal conductivity and propagation velocity of oscillation characteristics necessary for calculating the stress-strain state of the design elements is limited. In these conditions, there is a need for theoretical methods for calculating the thermophysical properties. The proposed theoretical methods based on forces of interatomic interaction calculation. The classical methods based on the hypothesis of continuity do not allow calculating the material thermophysical properties.
On the structure of the orthotropic 3D permeability tensor of an anisotropic porous body in heat and mass transfer problems
Authors: Ryazhskikh V I , Nikolenko A V , Konovalov D A
Published: February 2021

The structure of a 3D permeability tensor with orthotropic properties is proposed to describe various heat and mass transfer processes in anisotropic porous media. This structure of the permeability tensor has advantages over the monoclinic and triclinic because of the minimum number of elements to be determined, which greatly simplifies the formulation, conduct and processing of the corresponding experiments. In addition, the confirmation of the operability of such a structure opens up new opportunities for the artificial creation of porous materials with specified properties and the required anisotropy architecture on 3D printers. Using the Jacobians of rotations in the Cartesian reference system, the matrix of rotations is found as a result of successive multiplication of Jacobians by different angles around the axes of the base coordinate system. The final form of the tensor is identified as the product of the orthotropic tensor on the left and right by the turn matrix and the transposed turn matrix, respectively. This representation allowed us to calculate the inverse permeability tensor and synthesize a mathematical 3D model of Darcy-Brinkman type of unidirectional flow in a porous channel of rectangular cross-section on the example of hydrodynamic filtration of a Newtonian fluid. It is shown that such linearization does not level the property of anisotropy in a porous medium, while maintaining three-dimensionality.
Recovery of the hydrounit performance characteristics via a few observations
Authors: Kovartcev A , Nazarova A , Zakharchenko V
Published: February 2021

The performance characteristic of hydrounits is used very often in various control systems on hydro power plant for velocity control, power distribution, for displaying at different levels of automation pyramid for technicians, technologists, management and so on. As building of new HPP is very expensive, last years main investments in this sphere were made to reconstruction, modernization and increasing of efficiency of the existing HPPs. Before new or reconstructed hydrounit is put into industrial operation, it should pass a set of tests to check its operability at set parameters of safety operating conditions. In this case variety of hydrounit tests is significantly limited. Resulted from this fact there is a problem of the hydrounits performance characteristics recovery via a few observations. The present paper describes the hydrounit characteristics recovery method based on usage of limited number of experimental data. Results of examination of properties of the method offered are also described.
The use of the spatial-structural model of a video signal from the television scanistor in tasks of monitoring the geometric parameters of small objects
Authors: Arkhipov I O , Shelkovnikov Yu K , Meteleva A A
Published: February 2021

The paper proposes a video signal model for determining the size and coordinates of the light zone on a television scanistor. The key idea is to represent the profile of the light zone in the form of a vector of spatial and structural parameters that can localize the light zone and restore its width and illumination. The use of the spatial-structural model of the video signal allows expanding the scope of scanistor optoelectronic systems for monitoring the geometric parameters of small objects.
Analysis of the possibility of deterministic chaos occurrence during moving of an Earth remote sensing satellite with gyro dampers
Authors: Pankratov V M , Barulina M A , Golikov A V , Pankratova E V
Published: February 2021

The purpose of the work is the mathematical modeling and analysis of pitch oscillations of an Earth remote sensing satellite, in the point of view of the possibility of occurrence of deterministic chaos during the process of calming the natural vibrations relative to the satellite’s center of mass. A nonlinear mathematical model of oscillations of an Earth remote sensing satellite with floated gyrodampers with an integrated thermal control system based on Peltier thermopiles is constructed. According to the results of computer simulation by using the developed library of temperature perturbation models, it is shown that for some values of the parameters of the system under study, deterministic chaos can occur. Phase portraits of the transition of the satellite in pitch oscillation from regular to chaotic motions were constructed. Areas of deterministic chaos are created as functions of the parameters of systems with gyro dampers and the characteristics of external temperature and mechanical disturbances.
On a static solution to the contact interaction of a flexible rectangular in plane of a microshell with a rectangular in plane of microplate
Authors: Papkova I V
Published: February 2021

The mathematical model of the contact interaction of a flexible rectangular in plane of a spherical microshell and a flexible rectangular microplate is constructed. The material of the shell and plate is elastic isotropic and homogeneous. Kirchhoff hypotheses are taken into account. A system of nonlinear partial differential equations is derived from the Hamiltonian energy principle on the basis of a modified couple stress theory. The contact pressure function was determined according to the theory of B.Ya. Cantor. Contact interaction of sensitive elements of micromechanical sensors of inertial information in the form of a micro-shell and micro-plate is investigated. A micro-shell is affected by a static, uniformly distributed load. The static solution is determined by the establishment method. A new phenomenon related to the loss of stability is obtained.
Optimization the main thermodynamics parameters of the aviation turbofan engines with heat recovery in the aircraft system
Authors: Omar H H , Kuz’michev V S , Tkachenko A Y
Published: February 2021

Improving the fuel efficiency of aircraft engines is the main global trend of modern propulsion engineering. One of the promising ways to improve fuel efficiency is the use of complex thermodynamic cycles with heat recovery of exhaust gases. An important task in the design of engines with heat recovery is to select the main thermodynamic parameters process that ensures maximum efficiency of the engine in the aircraft system. The article presents the setting problem of optimization and selection of rational parameters of the working process of turbofan engines with heat recovery. Based on the developed method of multi-criteria optimization utilizing numerical simulations conducted and presented the results of optimization of parameters of the working process of turbofan engines with heat recovery in the system of aircraft according to criteria such as the total mass of the engine and fuel required for the flight, the specific fuel consumption of the aircraft on a ton per kilometre and the specific fuel consumption of engine (SFC). The developed mathematical model for calculating the mass of a compact heat exchanger presents to solve optimization problems at the stage of the conceptual design of the engine. The developed methods and models are implemented in the ASTRA program.
Order reduction for critical traveling wave problems
Authors: Shchepakina E
Published: February 2021

The paper deals with the order reduction for critical traveling wave problems. The specificity of such traveling waves is that they separate waves with qualitatively different behaviors. W e show how the application of the geometric theory of singular perturbations allows us to reduce the traveling wave problem for the original PDE system to the analysis the projection of the system onto its slow invariant manifold. W e illustrate this approach to the problem of finding the point-to-periodic traveling wave for the reaction-diffusion model.
Order reduction for problems with traveling wave solutions to reaction–diffusion systems
Authors: Shchepakina E , Tropkina E
Published: February 2021

The paper is devoted to the order reduction for traveling wave problems for reaction-diffusion systems. The use of the method of invariant manifolds of singularly perturbed systems allows us to replace the study of the traveling wave of the original PDE system with the analysis of their profiles in the ODE system with a lower order.
Modeling of the interaction of cylindrical bodies with complex surface properties
Authors: Kazakov K E
Published: February 2021

The axisymmetric contact problem of interaction between cylindrical bodies with complex surface properties (elastic properties or shapes) is described. For this problem, its mathematical model is constructed. It is mixed integral equation. An analytical solution for the problem of finding contact stresses under the bush is obtained. It allow one to make efficient calculations even when the coating nonuniformity and bush internal profile described by rapidly changing functions.
Latest results and future prospects of the pierre auger observatory
Authors: Miramonti Lino
Published: February 2021

The Pierre Auger Observatory is the largest observatory for the detection of ultra high energy cosmic rays (UHECRs). It allows a detailed measurement of the energy spectrum, the mass composition and the arrival directions of the primary cosmic rays with energies above 100 PeV. The data collected with the Pierre Auger Observatory show a suppression of the cosmic ray flux at energies above 40 EeV but the nature of this suppression is still unclear; according to theoretical prediction it could be caused by the interaction of cosmic rays with the CMB or by energy limitations of the cosmic rays sources. Another puzzle concerns the specific origin of UHECRs. Some indications can be obtained from studying the distribution of their arrival directions. Recently a dipole anisotropy has been observed which indicates that UHECRs have an extragalactic origin. I will present the recent results of the Pierre Auger Observatory about the energy spectrum, the mass composition and the arrival directions of UHECRs. I will also discuss the future prospects of the Observatory.
Hydrodynamical evolution and their light curves for a new GRB-Afterglow modal
Authors: Zouaoui E , Mebarki N
Published: February 2021

A model of a hydrodynamic evolution of an external shock produced by the deceleration of a relativistic jet ejected by a progenitor of the gamma ray burst is proposed and studied. The model shows new aspects and gives the most realistic description of the radiation energy produced by the fireball. The properties of the light curve of the GRB-Afterglows are also discussed.
The design of optimal reversible comparator circuit using new quantum gates
Authors: Slimani A , Benslama A
Published: February 2021

This paper presents a novel approach for designing reversible n-bit comparator based on new quantum gates. Their quantum equivalent implementations are also proposed. The design of comparator circuits is completed by using existing reversible gates and the above new reversible circuits. The comparative results are presented in terms of quantum cost, quantum delay and garbage outputs.
Phase space path integral for modified pöschl-teller potential
Authors: Allal M S , Bentag B
Published: February 2021

The phase space path integral for a particle inside the modified Pöschl-Teller potential hole (MPT) is exactly evaluated by using the delta functional technique. The bound-state energy-levels and the corresponding suitably normalized wave functions are derived.