bluuebunny/crossref_metadata_2025 huggingface dataset:
Supersonic Shock Wave with Landau Quantization in a Relativistic Degenerate Plasma*
Authors: Deka M. Kr. , Dev A. N.
Published: January 2020

A three-dimensional (3D) Burgers’ equation adopting perturbative methodology is derived to study the evolution of a shock wave with Landau quantized magnetic field in relativistic quantum plasma. The characteristics of a shock wave in such a plasma under the influence of magnetic quantization, relativistic parameter and degenerate electron density are studied with assistance of steady state solution. The magnetic field has a noteworthy control, especially on the shock wave’s amplitude in the lower range of the electron density, whereas the amplitude in the higher range of the electron density reduces remarkably. The rate of increase of shock wave potential is much higher (lower) with a magnetic field in the lower (higher) range of electron density. With the relativistic factor, the shock wave’s amplitude increases significantly and the rate of increase is higher (lower) for lower (higher) electron density. The combined effect of the increase of relativistic factor and the magnetic field on the strength of the shock wave, results in the highest value of the wave potential in the lower range of the degenerate electron density.
Negative Thermal Expansion and Spontaneous Magnetostriction of Nd2Fe16.5Cr0.5 Compound*
Authors: Hao Li-Yu , Yang Tie , Tan Ming
Published: January 2020

The structural, thermal expansion, and magnetic properties of the Nd2Fe16.5Cr0.5 compound are investigated by means of x-ray diffraction and magnetization measurements. The Nd2Fe16.5Cr0.5 compound has a rhombohedral Th2Zn17-type structure. There exists a small negative thermal expansion resulting from a spontaneous magnetostriction in the magnetic state of the Nd2Fe16.5Cr0.5 compound. The average thermal expansion coefficient is −1.06 × 10−6/K in a temperature range 299–394 K. The spontaneous magnetostrictive deformation and the Curie temperature are discussed.
Rejuvenation in Hot-Drawn Micrometer Metallic Glassy Wires*
Authors: Dong Jie , Feng Yi-Hui , Huan Yong , Yi Jun , Wang Wei-Hua , Bai Hai-Yang , Sun Bao-An
Published: January 2020

We report an enhanced rejuvenation in hot-drawn micrometer metallic glassy wires (MG wires) with the size reduction. Compared to metallic glasses (MGs) in bulk form, the modulus and hardness for the micro-scale MG wires, tested by nanoindentation methods, are much lower and decrease with the decreasing size, with a maximum decrease of ∼26% in modulus and ∼17% in hardness. This pronounced rejuvenation is evidenced by the larger sub-T
g relaxation enthalpy of the MG wires. The pronounced rejuvenation is physically related to the higher energy state induced by a combined effect of severely thermomechanical shearing and freezing the shear flow into a constrained small-volume region. Our results reveal that the internal states and properties of MGs can be dramatically changed by a proper modulation of temperature, flow stress and size.
Observation of Shubnikov-de Haas Oscillations in Large-Scale Weyl Semimetal WTe2 Films*
Authors: Chen Yequan , Chen Yongda , Ning Jiai , Chen Liming , Zhuang Wenzhuo , He Liang , Zhang Rong , Xu Yongbing , Wang Xuefeng
Published: January 2020

Topological Weyl semimetal WTe2 with large-scale film form has a promising prospect for new-generation spintronic devices. However, it remains a hard task to suppress the defect states in large-scale WTe2 films due to the chemical nature. Here we significantly improve the crystalline quality and remove the Te vacancies in WTe2 films by post annealing. We observe the distinct Shubnikov-de Haas quantum oscillations in WTe2 films. The nontrivial Berry phase can be revealed by Landau fan diagram analysis. The Hall mobility of WTe2 films can reach 1245 cm2V−1s−1 and 1423 cm2V−1s−1 for holes and electrons with the carrier density of 5 × 1019 cm−3 and 2 × 1019 cm−3, respectively. Our work provides a feasible route to obtain high-quality Weyl semimetal films for the future topological quantum device applications.
Bipolar Thermoelectrical Transport of SnSe Nanoplate in Low Temperature*
Authors: Zhou Li-Yan , Zheng Qi , Bao Li-Hong , Liang Wen-Jie
Published: January 2020

Bulk SnSe is an excellent thermoelectrical material with the highest figure-of-merit value of ZT = 2.8, making it promising in applications. Temperature-dependent electrical and thermoelectrical properties of SnSe nanoplates are studied at low temperature. Conductivity drops and rises again as temperature is lowered. The Seebeck coefficient is positive at room temperature and becomes negative at low temperature. The change of the sign of the Seebeck coefficient indicates influence of bipolar transport of the semiconductive SnSe nanoplate. The bipolar transport is caused by the Fermi energy changing with temperature due to different contributions from donors and acceptors at different temperatures.
Observation of Coulomb Gap and Enhanced Superconducting Gap in Nano-Sized Pb Islands Grown on SrTiO3*
Authors: Yuan Yonghao , Wang Xintong , Song Canli , Wang Lili , He Ke , Ma Xucun , Yao Hong , Li Wei , Xue Qi-Kun
Published: January 2020

We report high-resolution scanning tunneling microscopy (STM) study of nano-sized Pb islands grown on SrTiO3, where three distinct types of gaps with different energy scales are revealed. At low temperature, we find that the superconducting gap (Δ
s) in nano-sized Pb islands is significantly enhanced from the one in bulk Pb, while there is no essential change in superconducting transition temperature T
c, giving rise to a larger BCS ratio 2Δ
s/k

B

T
c ∼ 8.31 and implying stronger electron-phonon coupling. The stronger coupling can originate from the interface electron-phonon interactions between Pb islands and SrTiO3. As the superconducting gap is totally suppressed under applied magnetic field, the Coulomb gap with apparent V-shape emerges. Moreover, the size of Coulomb gap (Δ
C) depends on the lateral size of Pb islands (R) with Δ
C ∼ 1/R
0.35, indicating that quantum size effect can significantly influence electronic correlations. Our experimental results shall shed important light on the interplay among superconductivity, quantum size effect and correlations in nano-sized strong-coupling superconductors.
Fast Liquid Phase Epitaxial Growth for Perovskite Single Crystals*
Authors: Li Yu-Wei , Wang Xin , Li Guan-Wen , Wu Yao , Pan Yu-Zhu , Xu Yu-Bing , Chen Jing , Lei Wei
Published: January 2020

Semiconductors grown by the solution-processed method have shown low-cost, facile fabrication process and comparable performance. However, there are many reasons why it is difficult to achieve high quality films. For example, lattice constant mismatch is one of the problems when photovoltaic devices made of organ metallic perovskites. In this work, MAPbBr3 (

M
A
=
C

H
3

N

H
3
+

) perovskites single crystals grown on the surface of MAPbBr2.5Cl0.5 perovskites single crystals via liquid epitaxial growth method is demonstrated. It is found that when the lattice constants of the two perovskite single crystals are matched, another crystal can be grown on the surface of one crystal by epitaxial growth. The whole epitaxy growth process does not require high heating temperature and long heating time. X-ray diffraction method is used to prove the lattice plane of the substrate and the epitaxial grown layer. A scanning electron microscope is used to measure the thickness of the epitaxial layer. Compared with perovskite-based photodetectors without epitaxial growth layer, perovskite-based photodetectors with epitaxial growth layer have lower dark current density and higher optical responsibility.
Predicting Quantum Many-Body Dynamics with Transferable Neural Networks*
Authors: Zhang Ze-Wang , Yang Shuo , Wu Yi-Hang , Liu Chen-Xi , Han Yi-Min , Lee Ching-Hua , Sun Zheng , Li Guang-Jie , Zhang Xiao
Published: January 2020

Advanced machine learning (ML) approaches such as transfer learning have seldom been applied to approximate quantum many-body systems. Here we demonstrate that a simple recurrent unit (SRU) based efficient and transferable sequence learning framework is capable of learning and accurately predicting the time evolution of the one-dimensional (1D) Ising model with simultaneous transverse and parallel magnetic fields, as quantitatively corroborated by relative entropy measurements between the predicted and exact state distributions. At a cost of constant computational complexity, a larger many-body state evolution is predicted in an autoregressive way from just one initial state, without any guidance or knowledge of any Hamiltonian. Our work paves the way for future applications of advanced ML methods in quantum many-body dynamics with knowledge only from a smaller system.
A new derivation of singularity theorems with weakened energy hypotheses
Authors: Fewster Christopher J , Kontou Eleni-Alexandra
Published: January 2020

The original singularity theorems of Penrose and Hawking were proved for matter obeying the null energy condition or strong energy condition, respectively. Various authors have proved versions of these results under weakened hypotheses, by considering the Riccati inequality obtained from Raychaudhuri’s equation. Here, we give a different derivation that avoids the Raychaudhuri equation but instead makes use of index form methods. We show how our results improve over existing methods and how they can be applied to hypotheses inspired by quantum energy inequalities. In this last case, we make quantitative estimates of the initial conditions required for our singularity theorems to apply.
Foundations of optical diagnostics in low-temperature plasmas
Authors: Engeln Richard , Klarenaar Bart , Guaitella Olivier
Published: January 2020

Over the past few decades many diagnostics have been developed to study the non-equilibrium nature of plasma. These developments have given experimentalists the possibility to measure in situ molecular and atomic densities, electron and ion densities, temperatures and velocities of species in the plasma, to just name a few. Many of the diagnostic techniques are based on the ‘photon-in, photon-out’ principle and were at first developed to perform spectroscopy on atoms and molecules. Much later they were introduced in the research of plasmas. In this foundation paper we will focus on optical-based diagnostics that are now for quite some time common use in the field of low-temperature plasma physics research. The basic principles of the diagnostics will be outlined and references will be given to papers where these techniques were successfully applied. For a more comprehensive understanding of the techniques the reader will be referred to textbooks.
Spin-to-orbital angular momentum conversion in harmonic generation driven by intense circularly polarized laser
Authors: Li Shasha , Zhang Xiaomei , Gong Weifeng , Bu Zhigang , Shen Baifei
Published: January 2020

Spin-to-orbital angular momentum conversion (STOC) is a very important fundamental phenomenon governed by the conservation of total angular momentum (TAM). In optics, this conversion is usually associated with the vortex light carrying the orbital angular momentum (OAM). In this paper we demonstrate a new mechanism to achieve STOC via the interaction of an intense circularly polarized (CP) laser pulse with a solid density plasma target. We find that when a laser pulse with relativistic intensity is tightly focused, a longitudinal electric field is induced owing to the finite transverse size and profile of the laser field. Therefore, even for the normally incident CP laser, the induced longitudinal electric field can drive an oscillating vortex plasma surface to emit the vortex harmonics when the laser interacts with the plasma target. Based on simulations and theoretical analysis, we verify this harmonic generation mechanism and reveal the STOC process in the harmonic generation. It is shown that the spin angular momenta of multiple fundamental-frequency photons are converted to the OAM of a single harmonic photon because of the TAM conservation. We also discuss the dynamical symmetries in the harmonic generation process, which physically constrains the harmonic orders, as well as the angular momenta. In addition, if a vortex laser beam or a spiral phase plate is used, the OAM of the harmonic photon becomes more tunable and controllable. This study provides a deep insight into the nature of the spin–orbital interaction in optics.
The improvement of protection methods from the progressive collapse of one-storey industrial buildings
Authors: Trekin N N , Kodysh E N , Kelasiev N G , Shmakov S D , Chaganov A B , Terehov I A
Published: January 2020

The article deals with the main calculation methods of load-bearing systems for protection from the progressive collapse used both in Russia and in foreign countries. On the basis of the existing experience the recommended engineering decisions help to protect single-storey industrial buildings made of precast concrete structures from the progressive collapse. There are significant heights, rare step of columns and large spans of roof structures in this type of buildings. In the case of reinforced concrete buildings they also have significant loads from their own weight so it is a difficult to design the protection from the progressive collapse especially in the case of narrow conditions and in the reconstructed construction sites. The authors suppose that the use of the recommended engineering decisions help to perform effectively the protection from progressive collapse and to reduce time and financial costs.
Modeling of Damages of Steel Structures of Industrial Buildings
Authors: Buzalo N A , Alexeeva A S , Chernykhovsky B A
Published: January 2020

in this paper, the most common types of damage to metal structures were considered. Their mathematical models were specified in Ansys. In the framework of the problem under consideration, the stress-strain state of the samples in the elastic zone and beyond is studied, i.e. beyond proportionality, in this case it is necessary to perform non-linear analysis. Nonlinear mechanical properties of the material were set in the program. As a result of the calculation, the authors obtained curves of the dependence of the maximum strain in the middle of the rack on the magnitude of the applied force. the calculation results show satisfactory convergence with the experimental results. Thus, it is possible to perform a similar assessment of the decrease in the bearing capacity of the rack for damage not studied in the full-scale experiment.
Physical modeling of reinforced concrete structures exposed to emergency loads
Authors: Chemodurov V T , Korenkov P A , Leonenko Yu S , Korenkova O O
Published: January 2020

The article examines the role of dynamic collapse modelling for reinforced concrete structures exposed to emergency dynamic loads. The authors reviewed methodological approaches to test simulation of emergency loads applied to reinforced concrete structures with the aim to consider the scale effects revealed in manufacturing of test models of reinforced concrete structures. The comparative analysis is based on the examples of the authors’ previous computational and experimental investigations of the reinforced concrete building frames made of cast-in-situ reinforced concrete. The article determines regularities in the impact of physical and geometric similarities applicable to models and full-scale specimens. The obtained results can become a base for a mathematical description of the impact produced by scale effects that shall be considered in simulation of emergency dynamic loads for the given structures.
The terms of soils removal from the defects of the underground structures’ lining
Authors: Kulikova E Yu , Ivannikov A L
Published: January 2020

The lack of filtration reliability of bearing structures of urban underground facilities laid down at the design stage is associated with the unresolved issues of their filtration interaction with the adjacent soil or rock body. Water flows through the lining of the underground structure destroy the load-bearing structures, contribute to the removal of loose material into underground workings and create unacceptable microclimatic conditions for human stay. The question arises not only about the permissible degree of permeability of these structures, about the influence of filtration processes on the properties of the lining materials and their stability, but also about the relationship of water permeability of the bearing elements with the properties of the rock mass. Therefore, ensuring the filtration reliability of urban underground structures should be based on a set of protective measures aimed at involving in the work of the relevant properties of the underground object, and rock mass and technological methods of its construction, maintenance and operation. The problem of sealing the underground structure cannot be solved only by improving the concrete lining and raises the question of the need for measures to manage the characteristics of the state of the soil mass, which is the subject of this study.
On the reinforcement of thin-walled cold-drawn C-channel beams
Authors: Manuylov G A , Begichev M M
Published: January 2020

The paper considers the problem of stability of a thin-walled channel. Options for increasing the stability of the channel by changing its cross-section are proposed. Stiffness increased by adding triangular folds, as well as by adding stiffeners. The influence of initial imperfections of geometry in the channel model on the critical load of stability loss and postcritical behavior of the model is investigated. Imperfections were defined as deviations of the geometry of the pseudo-random amplitude.
Moment redistribution in concrete statically undetectable systems with FRP
Authors: Simakov O
Published: January 2020

Currently, engineers use, as a rule, the mechanics of elastic systems or take into account the inelastic properties of reinforced concrete without external reinforcement when performing calculations and designing the reinforcement of normal sections of reinforced concrete structures. It should be recognized that there is currently no model that takes into account the inelastic properties of normal sections of reinforced concrete elements with FRP. In this regard, an important issue is the evaluation of the influence of FRP on the redistribution of bending moments in a statically indeterminate system through a change in the stiffness of normal sections. This article analyzes the changes in the stiffness of normal sections, as well as the redistribution of bending moments in a statically indeterminate two-span beam on the basis of the existing model of inelastic deformations reinforced with external reinforcement sections with a model built on the basis of experiments (the actual stiffness of external reinforced normal sections).
Work flange connections of structural elements of an open profile on high-strength bolts
Authors: Shafray K , Shafray S
Published: January 2020

Design solutions of flange assemblies and their elements’ features for open structure rods of building structures are discussed in the article. The distribution of contact stresses both, between flanges and under bolt washers is obtained as a result of a numerical experiment. It is established that the nature of contact stress diagrams and the location (eccentricities) of lever forces depend on the ratio of flanges’ and bolts’ stiffnesses. The dependence of the bending moment in a flange on the magnitude of lever forces is revealed. High-strength connection bolts can work for eccentric tension, depending on the ratio of flanges and bolts stiffnesses.
Performance evaluation of the effectiveness of the use of core drivers in the construction of base plates
Authors: Chunyuk D Yu , Selviyan S M
Published: January 2020

This article is an example of the calculation of a foundation monolithic slab using void formers during the construction of an apartment complex consisting of three buildings located on one stylobation. In this example, we consider several options for calculating multi-hollow foundation slabs in order to determine the most cost-effective design. At the same time, a multi-hollow foundation slab should have the same rigidity and load-bearing capacity as usual.
Multi-factor analysis of technological operations of extinguishing exterior walls with a heat-insulating layer from concrete of low heat conductivity
Authors: Kustikova Y O
Published: January 2020

Improving the manufacturability of the construction of external walls in monolithic housing construction is achieved due to new structural and technological solutions. The main advantages of the technology of erecting monolithic external walls using concrete with low thermal conductivity in the heat-insulating layer are the reduction of the organizational and technological stages of erecting the external walls with the elimination of the technological gap between the stages, the absence of the need to attract specialized performers to erect the heat-insulating and enclosing layers of the wall, eliminating additional installation work and dismantling scaffolding during the construction of the facade, as well as reducing the number of manual processes and the nomenclature of building materials and products, the use of which is limited by the seasonality of work or requires additional costs to ensure their design physical and technical characteristics. To assess the significance of factors, a multivariate analysis technique was used.
Increase of fire protection and strength of wooden structures by modification in a thin surface layer by nanodispersion composites
Authors: Pokrovskaya E N
Published: January 2020

Currently, the industrial construction of multi-storey houses of wooden structures (DK) is increasing. In world practice, multi-storey buildings from a recreation center are being built in Austria, Great Britain, Norway, and Canada. In Russia, 9-13 storey buildings are being designed using a recreation center. High-rise construction using a recreation center for earthquake-prone areas is especially relevant. For modern multi-story building from a recreation center, effective surface fire protection should not increase the weight of structures. At the same time, their strength should increase. The solution of complex issues of DC fire protection in thin layers with a simultaneous increase in its strength is an unresolved problem.
Account of the force resistance in the calculation of reinforced concrete structures
Authors: Borovskih A V , Gorbachevskii V P , Pachomova L A
Published: January 2020

The aggressiveness of the environment of their placement has a direct impact on reinforced concrete structures. This work is aimed to present the method for constructing fundamentally modified equations of the force resistance of concrete and reinforcing steel. The results of this work present the method for the constructing quasi-linear equations of the force resistance of concrete and reinforcing steel for use in the calculation of reinforced concrete structures. The sequence for producing a quasi – linear equation of the force resistance of concrete and reinforcing steel, as well as the diagram of the stress – total relative deformations is presented.
Methods for subsoil modelling under dynamic impacts and multicomponent damping in SCAD FEA software with geophysical monitoring
Authors: Nuzhdin Leonid V , Mikhaylov Victor S , Voskresenskiy Mikhail N
Published: January 2020

In this paper, an integrated technology for performing finite element calculations in SCAD Office FEA-software and identification of dynamic characteristics of Soil-Structure Interaction models with the use of geophysical hardware REGISTR and SINUS is proposed.
Optimization of plane frame structure with consideration of semi-rigid connections
Authors: Van Tran Thi Thuy , Quyen Vu Thi Bich , Thuy Nguyen Le
Published: January 2020

Beam-column connections play an important role in the load capacity of frame structures. In Vietnam, in the current design calculation standards for steel frame structures, to simplify calculations, the beam-column connections in the frame structures is considered as the two idealized extremes of either rigid connection or pinned connection. The actual behavior of beam-column connection is neglected. The paper presents the optimization calculation of steel frame structure taking into account the semi-rigid beam-column connections. The optimization problem is solved by Genetic algorithm method and the calculation procedure was implemented by Matlab programming software. Some numerical examples are conducted and from there the conclusions and recommendations of calculations and design of steel frames will be proposed.
Comprehensive assessment of fire protective intumescent paint “terma”
Authors: Eremina T Yu , Korolchenko D A , Kuznetsova I N
Published: January 2020

Fire protection of steel structures is aimed at increasing their fire resistance, the indicator of which is the fire resistance limit. The paper presents a calculation approach to solution of the problem of critical heating time determining for building structures with intumescent compositions. Methodological approach for assessment of heating layers of intumescent fire protective coating for different types of steel structures is developed. The applied approach allows taking into account the influence of the basic thermophysical parameters of the fire protection composition on its efficiency. The paper presents the calculations for a particular coating, which allow to determine the dependences of the thicknesses of dry layers on different reduced metal thicknesses and to obtain relevant correspondences between the calculation results and experimental data.
Limit state of steel reinforced concrete round plates in the operational stage
Authors: Razzakov S R , Razzakov KH S , Razzakov J S
Published: January 2020

The results of the study of round thin reinforced concrete thin reinforced concrete and steel concrete slabs with external sheet reinforcement at short and long operational load are presented. According to the results of theoretical and experimental studies, the behavior of thin plates at various stages of the stress-strain state and also the possible fracture patterns, taking into account the flexibility of the contour structures of the changing properties of the materials and the duration of operation, are revealed.
An analytical solution to the problem of bending-torsional vibrations of a thin-walled rod
Authors: Ibragimov A
Published: January 2020

The article provides a brief overview of the works devoted to the stability and bending-torsional vibrations of thin-walled rods. The problem is formulated and an analytical solution to the problem of bending-torsional vibrations of a thin-walled rod is given. The analysis of the obtained solutions is given.
Seismic barriers: mathematical foundations and dimensional analysis
Authors: Ilyashenko A V
Published: January 2020

The concept of a vertical barrier embedded in soil to protect from seismic waves of the Rayleigh type is discussed. The principle idea for such a barrier is to reflect and scatter wave energy by the barrier, thus decreasing amplitude of surface vibrations beyond the barrier. Numerical FE simulations of a plane model are presented and discussed.
Simulation of Wireless Network Throughput in Providing the Monitoring of Building Structures
Authors: Grigoreva S V
Published: January 2020

The article shows the feasibility of using wireless networks in the field of construction monitoring. It is established that there is a need to increase the data transmission rate over the network in order to collect readings from distributed sensors in order to timely detect defects in building structures. An experiment with predefined parameters for the size of the transmitted packets was conducted using a software implementation of a model of network throughput assessment.
Towards Building Information Modelling for diagnosis, assessment and rehabilitation automation for existing buildings
Authors: Garyaev N A , Ayoub F
Published: January 2020

While building information modelling (BIM) developed for new buildings, the majority of existing buildings needs to be maintained, rehabilitated or reconstructed. The promising benefits of BIM motivate the researchers to extend the BIM functionalities for existing buildings. This paper presents a BIM-based computer application that we have developed for diagnosis of concrete structural elements based on a knowledge base acquired from multiple references and the opportunities of BIM technology.
The impact of hydro-wear parts of pumps for operational efficiency of the pumping station
Authors: Mamajonov M , Bazarov D R , Uralov B R , Djumabaeva G U , Rahmatov N
Published: January 2020

During the work considered questions of the occurrence of cavitation in hydro abrasive flows, which can lead to a rather complex phenomenon that is difficult to understand the essence of this process. Today, the wear of the working bodies of centrifugal and axial pumps, depending on the mode of their operation has not been learned much, and there has been developed a technique for selecting operating modes, taking into account the wear of their parts. Also, the results of complex laboratory and field studies on the intensity of wear of the flow elements of centrifugal and axial pumps are presented. It has been established that the alternating, pulsating load leads to an increase in the force of interaction of the hydro abrasive flow with the camera surface and increases its wear by 10 %, and also reduces the capacity of the pumping unit to 9%.
Search for optimal methods for calculating atypical spatial structures on the example of a climbing wall
Authors: Tarasov A V , Loktev D A , Deordiev S V , Petuhova I Y , Tarasov I V
Published: January 2020

The article presents an analysis of approaches to solving non-standard spatial structural schemes with the use of modern modeling and calculation tools, by the example of the construction of the climbing wall of a complex spatial shape.
Prediction of compatibility of polypropylene and modified basalt fibers
Authors: Galitseiskii K B , Matseevich T A , Askadskii A A
Published: January 2020

The compatibility of polymer structures was forecasted using the calculation scheme proposed by one of the authors for the analysis of polymer compatibility. The forecast was made for composite materials based on secondary polypropylene (PP) and short-chopped basalt fibers (BF). To verify the accuracy of the prediction, BF was treated with CCl4 vapors in a flow reactor in order to replace oxygen atoms with chlorine atoms. Next, the chlorinated surface was treated in a stream of CH4 to replace chlorine with hydrocarbon groups. Composites contained from 5 to 20% BF; each composite was heated at temperatures of 500, 650 and 750°C. The chemical structure of hydrocarbon groups most compatible with PP was determined by calculation using the Cascade computer program (INEOS RAS). IR studies, microanalysis, and X-ray fluorescence analysis showed the presence of such groups on the surface of BF that are chemically bonded to silicon atoms. The surface treatment performed by BF improves the mechanical properties of the composites. The modulus of elasticity reaches 2120 MPa with a BF content of 20% (for secondary PP this module is 705 MPa). The strength is 44,5 MPa (for secondary PP, the strength is 26,5 MPa). The specific impact strength reaches 18,3 kJ/m2 (for the initial secondary PP, this value is 14,4 kJ/m2).
An analytical solution with a given accuracy for a nonlinear mathematical model of a console-type construction
Authors: Orlov V , Kovalchuk O
Published: January 2020

On the basis of the results obtained for one of the variants of the mathematical model of the console-type construction with sudden application of the load described by a nonlinear differential equation, an analytical approximate solution with a given accuracy is constructed. The results of the numerical experiment are presented. The proposed mathematical approach allows on the basis of analytical solutions to calculate for any point the coordinates fracture during bending of the beam.
On the theory of constructing a numerical-analytical solution of a cantilever beam bend nonlinear differential equation of the first order
Authors: Orlov V , Chichurin A
Published: January 2020

We consider a first-order nonlinear differential equation with a movable singular point. For this equation, we built an analytical approximate solution of the special form. The theorem allowing obtaining an a priori estimation of such solution is proved. To illustrate theorem and our constructive approach we give the example. The given method may be generalized to nonlinear differential equations of the higher orders.
Arrival Probability Based Parking Algorithm for Elevator Group Control Systems
Authors: Ciflikli C , Tartan E O
Published: January 2020

A main concern in elevator group control system (EGCS) is quality of service in terms of average passenger waiting time. If no parking algorithm is applied, when an elevator enters an idle state, it remains at its current floor. An additional enhancement for the system can be using parking algorithms and sending idle elevators to park floors to reduce passenger waiting times. In elevator traffic, passengers are considered in three groups according to their travel intentions as incoming, inter-floor and outgoing passengers. Traffic components representing the ratios of these groups are major factors in determining traffic pattern. Overall passenger arrival probabilities can be described by weighted sum of incoming, inter-floor and outgoing arrival distributions with corresponding traffic components. Then, arrival probabilities can be used to obtain a general adaptive parking algorithm. In this study we propose a parking algorithm for EGCS based on arrival probabilities and investigate average waiting time under varying traffic conditions.
Finite element modelling of unbonded post-tensioned simply supported beam
Authors: Barkaya T R , Gavrilenko A V
Published: January 2020

This paper describes an experience of designing of some finite element models of unbonded post-tensioned simply supported concrete beam. It was purposed to evaluate a bending moment capacity, crack resistance, increment of pre-stressing force in reinforcement and deflection of models. Their behaviour under gradual loading was in the spotlight as well. There is short information about preliminary performed experimental study of beams. Parameters of physical models of beams obtained from experiment were used as initial data while finite element models were being created. Discussion of results obtained is listed. Their comparison with an experimental data is done.
Algorithm for parametric identification of mathematical models of viscoelastic materials
Authors: Erokhin S
Published: January 2020

Mathematical models containing fractional derivatives for viscoelastic materials and parametric identification problems are being considered in the paper. Specific attention is paid to statistical methods of data processing which allow increasing the accuracy of identification. A description of software implementing the presented techniques and algorithms is also given in the passage.
Investigation of Phase Portraits Belonging to Polynomial Dynamic Systems in a Poincare Disk
Authors: Andreeva I A , Efimova T O
Published: January 2020

The paper describes especially developed research methods and results for some original study of a broad dynamic systems’ family, which is characterized with the reciprocal polynomials in the right parts of differential equations which compose a system. The goal of this work is to obtain and analyze all the existing (and different in the topological meaning) phase portraits in a Poincare disk, as well as to indicate the criteria of each topological type of phase portraits appearance. Poincare methods of sequential transformations and displays have been successfully used along with a whole set of new research techniques developed for the purposes of this study. Over than 250 of different portraits were obtained and depicted eventually for different subsystems belong to the dynamic systems’ family under consideration. All portraits were described up to each the so-called invariant cell of the phase portrait, a boundary of it, and features of a phase flow in it, including it’s a source and a sink. Results of dynamic systems’ behavior research are useful for a wide spectrum of applications such as the mathematical modeling of physical processes, vital problems of civil engineering, for example, in the consideration of seismic stability of buildings etc., computing and producing systems, biological phenomena, and of sociological events.
About applicability of semi-Markov models of operation
Authors: Khayrullin R Z
Published: January 2020

The methodology is proposed for assessing the applicability of stationary semi-Markov models for the problems of efficient operation of control and measuring equipment. The methodology is based on the Euler method of construction a fundamental system of solutions for a system of ordinary differential equations with constant coefficients. The methodology is founded on the calculation of all eigenvalues (spectrum) and eigenvectors of the matrix of the system of differential equations. It is shown that for the classical model of operation of measuring equipment for a typical range of variation of the main parameters of the model (probabilities of failure, false failure and undetected failure), the characteristic equation of the system has two invariant eigenvalues and four eigenvalues that can be considered us functions of the model parameters. A qualitative analysis of the dependence of the spectrum of the matrix on the parameters of the model is carried out. The dependence of the non-invariant real eigenvalue, which plays a key role in the convergence of the solution of the dynamic model to the solution of the stationary semi-Markov model, on the parameters of the model is investigated in detail. The results of mathematical simulation are presented.
Modeling of subsidence of anthropogenic soil containing ice lenses
Authors: Bord E G , Shevchenko A A , Lavrov S N
Published: January 2020

The paper considers the possibilities of modelling of cyclic thermal effects on clastic water-saturated soil anthropogenic origin containing permafrost soil and ice lenses. In the formulation of the problem, there is uncertainty in the description of the structure of the layers, permeability coefficients, heat capacity and thermal conductivity. It is shown that the soil model allows the simultaneous implementation of filtration and convection modes depending on the degree of water cut in the layer. A formulation of the inverse problem is proposed, allowing an adequate interpretation of the log data.
Features extraction from non-destructive testing data in cyber-physical monitoring system of construction facilities
Authors: Kats V , Volkov A
Published: January 2020

Current paper presents a features extraction method when analyzing the acoustic emission (AE) control data of the technical condition of construction facilities as a part of decision support in cyber physical monitoring system. A set of statistical parameters that describe local properties of AE time series in time and frequency domains has been proposed. Furthermore, a features calculation method based on utilizing sliding windows with overlays in two time scales was introduced. Presented method has been pilot-tested during the technical diagnostics of the oil tank containing defects of different hazard classes.
Modeling of water permeability through the polymer nanocomposites
Authors: Matseevich Tatiana
Published: January 2020

The influence of chemical and physical parameters of polymer nanocomposites on the water permeability is analyzed. The chemical structure of the matrix polymer and the polar groups grafted onto the surface of the nanoparticles lead to the greatest influence. A large influence is exerted by the concentration of nanoparticles, their shape and size distribution. The direction of the penetration front in the nanocomposite sample has a lesser effect.
Mathematical modelling in cyber-physical construction systems
Authors: Titarenko Boris , Titarenko Roman
Published: January 2020

This paper deals with the problem of mathematical foundation for information block of cyber-physical system (CPS). CPS requires the involvement of a variety of information technologies. Their effectiveness is related to methods of data processing of contaminated data sets. The robust estimation means minimizing asymptotic bias of the estimates in the presence of contaminating observations. In the contrast to the approach of P. Huber and J. Tukey, where robustness is minimizing of the asymptotic variance of estimates, minimax asymptotic bias method is based on the maximum likelihood approach assuming an arbitrary contaminating distribution. Examples of this approach for the most common probability distributions and the ways of applying this approach are also given.
Study of the seismic isolation sliding belt: the case of a monolithic reinforced concrete building
Authors: Mkrtychev O V , Mingazova S M
Published: January 2020

This work highlights the application of an active seismic protection system using a sliding belt in the foundation to protect buildings and facilities located in earthquake-prone areas. The widespread type of seismic protection using rubber-metal supports (RMS) is complex and sometimes not cost-effective. The considered method of seismic protection using seismic isolation sliding belts has a number of advantages over the other types of seismic protection. However, the considered seismic isolation system still does not have an adequate mathematical model describing its action in the building-seismic isolation-foundation-base system. The study covered the efficiency of applying the seismic insulation sliding belt through the example of a 16-story monolithic reinforced concrete building. As a result of the calculations, the absolute accelerations, velocities, relative displacements, and intensity of stresses in the considered structure were obtained. An analysis of the calculations indicates the efficiency of seismic isolation using a sliding belt in the foundation for buildings constructed in earthquake-prone areas.
BIM as a tool for Green Building Certifications: an evaluation of the energy category of LEED, BREEAM and DGNB
Authors: Romano S , Riediger N
Published: January 2020

The Architecture, Engineering, and Construction (AEC) industry faces essential challenges related to the three sustainable pillars (social, economic and environmental). For instance, to decrease the carbon emissions, the consumption of energy and raw materials, to design sustainable cities and to improve the methodologies and technologies used to minimize cost and environmental problems. One alternative to overcome these challenges is the Green Building Certifications (GBCs), as for example Leadership in Energy and Environmental Design (LEED), Building Research Establishment Environmental Assessment Methodology (BREEAM), and German Sustainable Building Council (DGNB), and the new tools to support their process of implementation, for instance Building Information Modelling (BIM). The main objective of this paper is to study the viability of using BIM in the process of certification of energy category of LEED, BREEAM and DGNB for new projects using as a case study the building EUREF HAUS 12 – 13 located in Berlin - Germany. The methodology established is descriptive-exploratory and considers four research techniques, bibliography review, semi-structured interviews, BIM case study analysis, and work meetings with a BIM expert. The results illustrate that BIM can support all the energy requirements of LEED, BREEAM and DGNB and that despite the challenges that represent the implementation of BIM in GBCs, the advantages of it increases the efficiency of this process significantly.
Fatigue cracks in castellated I-beams under cyclic loads
Authors: Saiyan Sergey , Paushkin Alexander
Published: January 2020

The numerical calculation is carried out to predict the places of fatigue cracks, determine the fatigue life and the path of crack propagation of castellated beams, specifying the possibility of their use under multi-cycle loads. The method was implemented by using of the developed subroutine in the Ansys Mechanical software package in the parametric programming language APDL (ANSYS Parametric Design Language). The calculation is carried out in the form of successive quasi-static iterations.
Modeling of accidental leaks from utility lines during calculation of the temperature regime of permafrost soil bases of buildings
Authors: Rabinovich Mikhail
Published: January 2020

Article presents technique for numerical calculation of temperature regime of the buildings on permafrost soils with consideration of thermal effects of leakage from utilities. Enthalpic model of heat exchange is used.
Using counterfactuals from macroeconomic models to assess risks to accomplishment of structural innovations
Authors: Passmore D , Borkovskaya V
Published: January 2020

A macroeconomic model often described as an input-output model, is specified mathematically to characterize production and consumption in an economy. Perturbations of attributes this macroeconomic model allow the examination of counterfactuals - hypothetical scenarios that run “counter to the facts” of an existing reality – to assess risks to accomplishments of structural innovations in light of plausible endogenous or exogenous shocks to the economy.
Modeling and analysis of three-layer floor slabs made of composite materials
Authors: Khayrnasov K Z
Published: January 2020

A three-layer composite floor slab is considered, consisting of two external bearing layers made of a multilayer composite material, and a filler layer between the bearing layers made of polystyrene. Relations are given to determine the characteristics of multilayer composite materials with different locations of the base layers of the material. The technique of the optimal arrangement of the basis of the composite material in layers is given. Methodology for calculating three-layer structures consisting of external bearing layers and a filler layer between them. The analysis of the results and prospects of using three-layer composite floor slabs in construction.
Mathematical model and calculation of the working part of the power plant
Authors: Kornilov A , Vasileva E
Published: January 2020

This article deals with the problem of the flow around a thin profile with perforations on the contours. The perforations are simulated using a “sink-and source” hydrodynamic model. The formulas for calculating the main vector of the flow pressure forces on the profile as well as that of the moment of the profile regarding the front edge have been obtained.
Modeling of deformation processes of structural steels along circular paths
Authors: Zubchaninov V G , Alekseev A A , Gultiaev V I
Published: January 2020

To verify the mathematical model of the theory of processes, numerical calculations of the complex elastoplastic deformation of steel along a flat curvilinear trajectory with simultaneous tension-compression with torsion were carried out. Comparison results are compared with the data of the physical experiment. It has been shown that the mathematical model used qualitatively and quantitatively satisfactorily describes the basic effects of complex plastic deformation for a given class of paths.
Fatigue strength assessment of track rollers
Authors: Götz Sebastian , Schröder Stefan
Published: January 2020

The paper presents a general concept for fatigue strength assessment in rolling contact between track roller and rail. The multi-axial stress state is analysed using the critical plane method. Depending on the orientation of the section plane, different load cycle combinations result with different stress-amplitude and mean-stress combinations. The Haigh diagram outlines the fatigue strength of the material. The load cycles in all section planes are plotted there and the safety factor can be determined directly. In comparison to other empirical concepts, similar values are obtained for the allowable maximum contact pressure. The advantage of this method is its general applicability, without any restrictions regarding the geometry or material.