bluuebunny/crossref_metadata_2025 huggingface dataset:
High-efficiency sound absorption by a nested and ventilated metasurface based on multi-slit synergetic resonance
Authors: Liu Hongxing , Wu Jiu Hui , Ma Fuyin
Published: February 2021

A nested, sound-absorbing, ventilated metasurface was proposed based on multi-slit synergetic resonance, which could simultaneously achieve high-efficiency (>0.85), sound absorption, and effective (speed ratio >0.67) ventilation in a frequency range of 470–657 Hz. The unit of the sound-absorbing and ventilated metasurface (USAVM) consisted of a ventilation channel and a stepped micro-slit absorber, which could effectively trade-off ventilation and absorption performance. The sound absorption mechanism was revealed via the coupling of the ventilation channel and micro-slit absorber, relying on strong air friction and the slit walls near the resonance frequency. Furthermore, after a parametric study of the USAVM, a compact nested metasurface with a thickness of only 39.1 mm (1/17 wavelength) was constructed using eight parallel USAVMs, with a surface panel area of only 1/7 of the traditional parallel structure. Finally, the sound absorption and ventilation performance of the nested metasurface were verified experimentally. In addition, the absorption bandwidth could be further improved by using more USAVMs. This work provides a new possibility for achieving highly efficient sound absorption with a subwavelength ventilated structure in a low-frequency range that could be applied in buildings or industrial areas.
Elucidating the dominant mechanisms in burn rate increase of thermite nanolaminates incorporating nanoparticle inclusions
Authors: Julien Baptiste , Wang Haiyang , Tichtchenko Emilian , Pelloquin Sylvain , Esteve Alain , Zachariah Michael R , Rossi Carole
Published: February 2021

It was experimentally found that silica and gold particles can modify the combustion properties of nanothermites but the exact role of the thermal properties of these additives on the propagating combustion front relative to other potential contributions remains unknown. Gold and silica particles of different sizes and volume loadings were added into aluminum/copper oxide thermites. Their effects on the flame front dynamics were investigated experimentally using microscopic dynamic imaging techniques and theoretically via a reaction model coupling mass and heat diffusion processes. A detailed theoretical analysis of the local temperature and thermal gradients at the vicinity of these two additives shows that highly conductive inclusions do not accelerate the combustion front while poor conductive inclusions result in the distortion of the flame front (corrugation), and therefore produce high thermal gradients (up to 1010 K.m−1) at the inclusion/host material interface. This results in an overall slowing down of the combustion front. These theoretical findings contradict the experimental observations in which a net increase of the flame front velocity was found when Au and SiO2 particles are added into the thermite. This leads to the conclusion that the faster burn rate observed experimentally cannot be fully associated with thermal effects only, but rather on chemical (catalytic) and/or mechanical mechanisms: formation of highly-stressed zones around the inclusion promoting the reactant mixing. One additional experiment in which physical SiO2 particles were replaced by voids (filled with Ar during experiment) to cancel the potential mechanical effects while preserving the thermal inhomogeneity in the thermite structure confirms the hypothesis that instead of pure thermal conduction, it is the mechanical mechanisms that dominate the propagation velocity in our specific Al/CuO multilayered films.
Dry sonication process for preparation of hybrid structures based on graphene and carbon nanotubes usable for chemical sensors
Authors: Prosheva Marija , Ehsani Maryam , Pérez-Martínez Bertha T , Blazevska Gilev Jadranka , Joseph Yvonne , Tomovska Radmila
Published: February 2021

The combination of graphene (G) and multi-walled carbon nanotubes (MWCNTs) creates three-dimensional hybrid structures particularly suitable as next-generation electrical interface materials. Nevertheless, efficient mixing of the nanopowders is challenging, unless previous disaggregation and eventual surface modification of both is reached. To avoid use of solvents and multistep purification process for synthesis of stable G/MWCNTs hybrids, herein, a novel dry method based on an air sonication process was used. Taking advantage from the vigorous turbulent currents generated by powerful ultrasonication in air that induces strong thermal convection or radiation to and from the particles, it simultaneously ensures disentanglement of the large MWCNT bundles and G exfoliation and their only mild surface modifications. By changing the ratio between MWCNTs and G, a range of hybrids was obtained, different in surface morphology and chemistry. These hybrids have shown great potential as sensing material for designing mass-based sensors for toxic gases and chemiresistor for vapors detection.
Spectral characteristics of broad band-rejection filter based on Bragg grating, one-dimensional photonic crystal, and subwavelength grating waveguide
Authors: Khonina S N , Kazanskiy N L , Butt M A
Published: February 2021

In this paper, the spectral characteristics of broad band-rejection filters composed of Bragg grating (BG), one-dimensional Photonic crystal (1D PC) and subwavelength grating (SWG) waveguide is discussed. The numerical study is conducted via 3D-finite element method (3D-FEM). To provide a fair comparison of the bandwidth and extinction ratio (ER) of the filter designs based on three different approaches, the waveguide width, height, length, grating period are kept constant. For the filter performance analysis, the grating period is fixed at 400 nm while the remaining geometric parameters are optimized to obtain the maximum ER and bandwidth. The maximum ER of >24 dB is obtained for all the three filter models having a footprint of 13.85 × 1 μm2 while the band-rejection bandwidth of BG, 1D PC and SWG waveguide is 158 nm, 432 nm and 295 nm, respectively. We believe that the study presented in this work will assist the researchers to choose the appropriate filter configuration to obtain maximum filter performance.
Deposition pattern of drying droplets
Authors: Yang Xiuyuan , Jiang Zechao , Lyu Peihan , Ding Zhaoyu , Man Xingkun
Published: February 2021

The drying of liquid droplets is a common daily life phenomenon that has long held a special interest in scientific research. When the droplet includes nonvolatile solutes, the evaporation of the solvent induces rich deposition patterns of solutes on the substrate. Understanding the formation mechanism of these patterns has important ramifications for technical applications, ranging from coating to inkjet printing to disease detection. This topical review addresses the development of physical understanding of tailoring the specific ring-like deposition patterns of drying droplets. We start with a brief introduction of the experimental techniques that are developed to control these patterns of sessile droplets. We then summarize the development of the corresponding theory. Particular attention herein is focused on advances and issues related to applying the Onsager variational principle (OVP) theory to the study of the deposition patterns of drying droplets. The main obstacle to conventional theory is the requirement of complex numerical solutions, but fortunately there has been recent groundbreaking progress due to the OVP theory. The advantage of the OVP theory is that it can be used as an approximation tool to reduce the high-order conventional hydrodynamic equations to first-order evolution equations, facilitating the analysis of soft matter dynamic problems. As such, OVP theory is now well poised to become a theory of choice for predicting deposition patterns of drying droplets.
Research on Intention Perception of Air Pollution Control Based on Text Analysis
Authors: Pan Lu , Guan Changqing , Li Jiatong
Published: February 2021

In recent years, the issue of air pollution has attracted unprecedented attention, governments at all levels have issued intensive air pollution prevention and control policies to deal with air pollution[1], however, it is worth paying attention to how people perceive the intention of air pollution control and whether the effect can meet the actual demands of the public. This paper adopts text analysis method and uses the information of Micro Blog platform, especially the short text information, as the research object with the help of ROETCM tool to crawled the data related to air pollution control, so as to analyze the Internet users’ perception of the effect of air pollution control, at the same time, it provides reference for better, more practical and more effective control of air pollution.
New Spraying Modelling of Special Surfaces for Environmental Protection
Authors: Chen Shiming , Chen Yan , Yang Guichun , Zhou Shuang , Chen Wenzhuo , Guan Jinfa
Published: February 2021

Research on spraying models of special profiles has a great significance on optimizing spraying quality, saving paint and protecting environment and health of workers. This article establishes a paint deposition model including the spray flow field model and impact adhesion model based on the Euler-Euler method. The model is solved by using polyhedral mesh to divide the fluid calculation domain and the coupled SIMPLE algorithm to compute the governing equations. The methods of spraying along the bus bar and circumferential spraying are applied to simulate and test the conical surface and the arc surface successively. Results of the experiments demonstrate the errors of the four cases are all less and confirm that the established paint deposition model is suitable for spraying research on conical outer surface.
Analysis of the Key Factors of Pumping Well System Efficiency for Oil Field Based on Multiple Regression
Authors: Yao Bin
Published: February 2021

Many factors are affecting the efficiency of the pumping well system and the lack of pertinence in oil well governance. It is proposed to use the block as a unit to use the multiple regression method to study the key influencing factors of the system efficiency, determine the degree of influence of various factors on the system efficiency through standardized regression coefficients, and grasp the main contradictions that restrict the efficiency of the oil well system. Guide the adjustment and optimization of oil wells, provide theoretical support for the targeted management of pumping well system efficiency, and improve the comprehensive management level of the oilfield.
Integrated Energy Service Package Design Based on User Profile and Cost-benefit Analysis
Authors: Xu Weiting , Tang Quan , Wang Haiyan , Xu Hao , Cheng Chao , Wang Ziyao , Li Huaqiang
Published: February 2021

At present, with the acceleration of energy transition and the continuous deepening of power market reform, energy system forms in China are showing new development trends. In order to strengthen the flexibility of the power market and solve the problem of single sales model, this paper used user portrait technology and cost-benefit analysis to analyze the IES package qualitatively and quantitatively. Qualitative analysis provides the packaged purchase mode for users; in the quantitative analysis, combined with the package-based Apriori algorithm, a model of users’ willingness to buy packages and a fixed-capacity model with the objective function of maximizing service provider revenue were established. Finally, based on five types of integrated energy services: power substitution service, PV service, CCHP service, energy saving renovation and energy efficiency improvement service, and operation and maintenance service, the reliability and scientificity of the model were verified through calculation examples. And by selling integrated energy services in the form of packages, both users and service providers can obtain certain benefits, achieve the goal of “1+1>2” and increase new sales methods in the power market.
Economic Analysis of Deep Peak-Shaving Reform of 600MW Thermal Power Unit in Beijing-Tianjin-Tangshan Power Grid
Authors: Guo Yujie , Tian Xueqin , Xu Tong , Wang Xinlei
Published: February 2021

Promoting deep peak-shaving reform to excavate the peak-shaving potential of thermal power unit is an important way to solve the renewable energy consumption contradiction in Beijing-Tianjin-Tangshan power grid, which is restricted by the rationality of deep peak-shaving revenue. Based on the peak-regulation auxiliary service in Beijing-Tianjin-Tangshan power grid, this paper analyses the economy of deep peak-shaving reform of a 600MW thermal power unit and the effect of peak-shaving demand and coal price, providing reference for the operation management of thermal power units.
An Approach of Top-DOWN Electric Generation Knowledge Graph Construction
Authors: Liang Hao , Peng Xiaojun , Zhao Ningning , Duan Liguo , Yu Pengfei , Fu Da
Published: February 2021

Knowledge Graph technology is a key research area of artificial intelligence technology. It has an obviously advantage in semantic processing and content interconnection, and widely used to provide intelligent information services in the open domain such as Web intelligent, NLP, user profile, etc. With the exploration and attempt of Knowledge Graph in vertical fields, it is confirmed that it can accelerated the intelligence application in all the electric generation life cycle, such as operation optimization, technical overhaul, intelligent marketing, material procurement, equipment maintenance. A Top-Down construction method of electric generation Knowledge Graph is proposed under the Kraftwerk-Kennzeichen system (KKS) to integrate electric generation knowledge and the knowledge management formation.
Numerical Investigation of Flow Dynamics and Improvement of Hot Primary-air Pipe Systems in Power Generation Plants
Authors: Yan Qingyun , Li You , Zhu Yuanhong , Luo Guoquan , Zheng Haitao , Liang Damei , Ye Xuemin
Published: February 2021

The pressure losses of the hot primary-air pipe system have a great influence on the economic operation of a pulverizing system. To balance the flow resistance for different branches, Fluent was applied to simulate flow dynamics and pressure drop for a hot primary-air pipe system, and two improvement schemes were proposed. Numerical simulation reveals that for the original configuration, the flow losses of each branch are quite different, and the large resistance of some branches is mainly caused by pipe tees. After improvement, the flow regime has been significantly polished, and the total pressure drop of different branches is greatly reduced. Compared with the original configuration, the total pressure loss of branch B and branch D in case 2 is reduced by 65% and 53%, respectively, then an approximately equal pressure drop of each branch is achieved after structure improvement.
Optimal Sensor Placement and Fault Diagnosis Model of PV Array of Photovoltaic Power Stations Based on XGBoost
Authors: Wang Hai , Sun Fengjie
Published: February 2021

As an important part of photovoltaic power stations, daily monitoring and maintenance of photovoltaic array are quite necessary. In order to be able to accurately locate the faulty module and diagnose fault types. The fault diagnosis model which based on XGBoost optimized by GridSearchCV on optimal sensor placement is proposed in this article. First, the change laws of external electrical characteristics of photovoltaic modules under the control of MPPT technology are analyzed in different fault states. On this basis, the parameters which can locate the faulty PV modules and the input of the XGBoost PV fault diagnosis model are obtained. Finally, during the process of the simulation and experiment, the failure data measured by the multi-sensor method can be used as a positioning quantity to locate the faulty module. The comparison results with the other three algorithms (LR, RF, XGBoost) prove that the performance of GS-XGBoost algorithm has great advantages in judging PV fault types (short circuit, open circuit, aging).
An Improved Shrunken Primal-Dual Subgradient (i-SPDS) algorithm for Optimization in Large-Scale Networked Environment
Authors: Luo Kui , Wang Qinghua
Published: February 2021

Large-scale optimization in networked environment is challenged by scalability. To address this challenge, this paper sets its aim on developing algorithms for optimization problems with strongly coupled objective function and global constraints. As a radical improvement of the state-of-the-art algorithms, this paper develops an improved shrunken-primal-dual subgradient (i-SPDS) algorithm that establishes fast convergence and eliminates optimality gap. The developed algorithm is rather generic in that it can be readily implemented in any applications that involve large-scale networked environment. Simulations are conducted to demonstrate the efficacy and efficiency of the proposed i-SPDS.
Application of Particle Swarm Optimization in Overturning Moment of Crawler Crane
Authors: Xu Haixiang , Zhang Ye , Lei Juyang , Wu Fengqi , Gong Wen
Published: February 2021

The rotating angle is one of the important operation parameters of jib crane, while the on-site survey of slewing angle is a difficult problem to evaluate the accuracy of angle display. This paper put forward a survey methodology based on the coordinate data around the rotation of marked points on the crane boom, and constructed the cost function by the geometric relations of marked point trajectory, used the particle swarm optimization algorithm to find the optimal solution of estimated angle. The simulation, laboratory experiment and on-site tests showed the survey methodology has the satisfied accuracy and be easy to implement.
First and second order sensitivity analysis of discontinuous parametric periodic systems
Authors: Wójcicki Z
Published: February 2021

The paper concerns sensitivity analysis of discontinuous parametric periodic systems. The eigenderivatives of monodromy matrix (Floquet transient matrix) were the first calculated. Then the first and second derivatives of multiplier, which are the complex eigenvalues of monodromy matrix, were obtained. Then, by solving the sensitivity equation obtained in this way, to evaluate the first and second derivative of monodromy matrix and finally the first and second derivatives of multipliers. The theory has been expanded to cover a class of discontinuous parametric periodic excitations, including a situations when: the period of parametric excitation depends on the design parameters, the position of discontinuity points depends on the design parameters, and both discontinuity points and parametric constraints are a function of the design parameter. In analysis of discontinuous parametric systems the definition of distributional derivatives was applied.
Absorbers impact on the reliability of structures subjected to random vibrations
Authors: Podwórna M , Grosel J , Śniady P
Published: February 2021

The paper considers the problem of optimizing the absorber parameters when random vibrations of the structure create a filtered Poisson process. A new parameter optimization criterion was proposed, consisting in minimizing the probability of the maximum vibrations of the structure exceeding a certain permissible value of displacements. This criterion means maximizing the reliability of the vibrating structure with regard to the maximum vibration amplitudes.
Third formulation of the space-time finite element method
Authors: Kacprzyk Z
Published: February 2021

The paper explains differences existing between the space-time finite elements, which fundamentals were presented by the Kączkowski in 1975 and 1976, and its modification. The replacement of load with concentrated forces and moments (which are to satisfy equilibrium conditions at nodes) was given up, namely in the latter one; instead, a requirement was made that functions approximating the solution would satisfy differential equation in inter-node areas in a specified integral way. This leads to a system of algebraic equations, in which kinematic parameters existing in the solution approximating functions are the unknowns. Displacements and their derivatives (of any order) at nodes are those parameters.
Dynamic and static response of a slightly compressible hyperelastic solid
Authors: Franus A , Marek A
Published: February 2021

The paper presents dynamic and static response of a slightly compressible hyperelastic solid. Material models under consideration are obtained by extending incompressible material models which are consistent second and third order approximation of existing stored energy function in terms of a deformation measure, namely MCMV and MCIZ. The problems of a uniaxial compression of a rod and a twisting column are solved using ABAQUS which is a powerful finite element program designed for general use in nonlinear problems. The models are defined with a help of user subroutine UHYPER. In the case of including dynamic effects, an implicit integration scheme available in the software is used. For the twisting column problem, results are compared against available in the ABAQUS library polynomial model where the volumetric stored energy function does not meet basic growth conditions. Experimental data on synthetic rubber neoprene published in the literature is utilized.
Modern lightweight deployable engineering structures
Authors: Al Sabouni-Zawadzka A , Zawadzki A , Gilewski W
Published: February 2021

The paper concerns the formulations and areas of possible scientific research in the field of modern deployable structures. The key problem is to provide a precise definition of modern deployable structures and to define the inherent properties that such structures should have. The objective was accomplished by specifying how the words deployable and lightweight are understood and assigning the constructions the necessary smart features. The defined features are fulfilled by tensegrity structures whose characteristics, from the point of view of deployability, are given in the paper.
The associated non-stationary thermal elasticity problem for a two-layer plate
Authors: Shlyakhin D A , Kusaeva Zh M
Published: February 2021

A new analytical solution of a non-stationary thermal elasticity problem for a rigidly fixed round two-layer plate was constructed. The case of temperature change on its upper face surface is considered and the heat exchange of the lower face surface with the environment is taken into account. When constructing a General solution, the mathematical apparatus for separating variables in the form of finite integral Fourier–Bessel transformations and generalized biorthogonal transformation is used. The solution peculiarity is the application of control and measuring device. The calculated relations make it possible to determine the stress-strain state and the distribution nature of the temperature field in a rigid round two-layer plate under any external temperature influence.
Related thermoelastic elastomeric task for cylinder
Authors: Shlyakhin D A , Kalmova M A
Published: February 2021

A new closed solution of the coupled non-stationary problem of thermoelectroelasticity for a long piezoceramic radially polarized cylinder is constructed when the boundary conditions of the 1st kind of thermal conductivity are satisfied on its front surfaces. The case is considered when the rate of change of the temperature field does not affect the inertial characteristics of the elastic system, which makes it possible to include in the initial calculated relations of the problem under consideration the linear equations of equilibrium, electrostatics and thermal conductivity with respect to the radial component of the displacement vector, electric potential, as well as the function of changing the temperature field. The calculations use the classical Fourier law of thermal conductivity. To solve the problem, the mathematical apparatus of incomplete separation of variables is used in the form of a generalized biorthogonal finite integral transformation (KIP), based on a multicomponent relation of eigenvector-functions of two homogeneous boundary value problems. An important point in the procedure of the structural algorithm of this method is the selection of the adjoint operator, without which it is impossible to solve non-self-adjoint linear problems of mathematical physics.
Parametric study of the stress state of beams with round holes in pure bending
Authors: Saiyan S , Paushkin A
Published: February 2021

A parametric study of the stress state of a rectangular cross-section beam with round holes in pure bending is performed by the finite element method implemented in the ANSYS Mechanical APDL software package. Correction coefficients were obtained for normal stresses determined by strength of materials methods. The coefficients of stress concentration during bending were determined depending on the size of the holes, as well as the distance between them. The research results obtained can be used in practical problems of designing perforated beams.
Numerical study of the stress-strain state of the vertical four-compartment cylindrical tank
Authors: Saiyan S , Paushkin A
Published: February 2021

A numerical study of the stress-strain state of the construction of the vertical four-compartment cylindrical tank at the stage of operation for storing various substances has been carried out. The purpose of the finite element calculation is to determine the optimal value of the thickness of its load-bearing walls and partitions, which ensure the mechanical safety of the construction under different modes of filling the containers. The reliability of the calculation results, which are carried out both in linear and geometrically nonlinear formulations, is provided by calculations in two software packages SCAD and ANSYS Mechanical APDL with comparison of solutions.
Stress-stain state in elastic spherical shells under the action some asymmetrical of circular loads
Authors: Astakhova A
Published: February 2021

The paper presents the basic differential equations for calculating shells of rotation. It is considered that the material of the shell works beyond the elastic limit. The conclusion of the resolving system of differential equations is based on the linear shell theory and the Kirchhoff-Love hypothesis. The physical correlations are based on the small elastic-plastic deformation theory. With the construction of the solution of the load function, also unknown resolving functions expand to the Fourier series along the circumferential coordinate. In the present work, the action of the asymmetrical distribution along the parallel loads is considered. The solution is approached by the elastic decisions method. The study of stress-stain state in the isotropic spherical shells is presented in the work. The results of the calculation are presented in the example of a spherical shell. The work of the material beyond the elastic limit is taken into account using assuming linear hardening of the material. The shell is loaded with ring distributed loads, and they are applied on a certain segment in a parallel circle. The diagrams of bending moments and areas of the appearance of plastic deformations along the thickness of the shell are presented. The areas of plastic deformations for ring loads distributed along the parallel relative to the zero meridian in the range of 45, 90,135 degrees are shown.
Plate tensegrity structures controlled with self-stress
Authors: Martyniuk-Sienkiewicz K , Al Sabouni-Zawadzka A
Published: February 2021

The present paper focuses on the analysis of plate tensegrity structures based on the 3-strut simplex module. Two structural systems are considered: a single plate tensegrity module and a multi-module segment. It is proved that the implementation of plate elements in the basic tensegrity module not only opens new application perspectives, but also increases its stiffness. The analyses are performed with the use of the finite element method (FEM), using the second order theory and the geometrically nonlinear analysis.
Results of the study of vibrations of concrete structures of the hydropower plant building
Authors: Evdokimov S V , Seliverstov V A , Orlova A A
Published: February 2021

The paper considers the results of studying vibrations of certain components of the hydropower plant building and their influence on the structure of the building as a whole. Vibration loads on various elements of the hydropower plant building which can cause damage to the building, thereby reducing the operational reliability of the whole structure and doing potential harm to the environment and human life support, is analyzed. The necessity for vibration monitoring of structures which should be conducted constantly or periodically to determine the present condition of structures is reasoned. Vibrations of the section concrete parts and vibrations of hydroelectric power plant units are considered. To detect the vibrational movements of the section as a solid body on an elastic base Section № 2of the hydropower plant building has been chosen. The recording of vibrations has been conducted for all three components: Z (vertical), H II (horizontal, parallel to the flow) and H ⊥ (horizontal, perpendicular to the flow) and the obtained data are given in this paper. The intervals of observed and dominant periods of vibrations are estimated. The research provides the data on amplitudes and accelerations of vibrations, as well as on the maximum recorded peak-to-peak swing. Based on the analysis of the received vibrograms, it is stated that the recorded vibrations are non-periodic and have a relatively narrow range of periods. In conclusion it is underlined that in order to determine the maximum possible amplitudes of section vibrations as well as to calculate the corresponding dynamic stresses in ceiling trusses it is necessary to observe vibrations when hydraulic units are operated simultaneously and the flow passes through the fully open bottom spillways of the inspected section.
To the optimization model of flexible reinforced concrete elements in monolithic frames of buildings
Authors: Tamrazyan A G
Published: February 2021

This article examines a three-span 8-storey frame building with the aim of optimizing the girders based on heuristic algorithms. A comparative analysis of modern heuristic algorithms for optimizing bending elements as applied to reinforced concrete frames of monolithic multi-storey buildings for the possibility of their use in practical engineering calculations. A mathematical model of the adapted algorithm has been formed that meets the requirements of Russian standards. The target function for cost has been determined, including the cost of materials (concrete and reinforcement), formwork, construction with the corresponding rise in price coefficients. In this case, the girder is optimized, since, despite the fact that their number in the building frame is 24, the cost is about 65% of the total cost, including reinforced concrete columns in the amount of 32.5 constant parameters and 19 variable parameters are selected, a set of limitations of the optimization algorithm was developed, including regulatory requirements for the calculation of limit states, design requirements for the reinforcement of the girder and its geometric characteristics, including the concrete cover, the step of the rods, anchoring, etc. The calculation of girders as part of a reinforced concrete monolithic frame of an 8-storey building was carried out using the developed methodology and the comparison of the results obtained with numerical calculations and solutions obtained by other methods. It is shown that the results of numerical calculations have a sufficiently high efficiency of the developed optimization technique. The final cost is after 100.000 iterations. Savings in terms of the main design characteristics range from 3 to 13%, depending on the complexity of the problem and the accepted constraints.
Investigation of the humidity regime of multilayer enclosing structures of buildings and structures
Authors: Vytchikov Yu S , Saparev M E , Kostuganov A B
Published: February 2021

The article describes an approximate analytical method for calculating the moisture regime of multilayer building envelope structures. The novelty of the proposed method lies in the use an analytical dependence for determination the position of the flatness possible condensation, obtained as a result of studying the function which is the difference between the partial pressures of water vapor in the considered section the enclosing structure and the partial pressure of saturated water vapor at the extremum. The article presents the results of calculating the moisture regime of the outer wall of a residential building under construction in Samara using monolithic sandless expanded clay blocks with a density equal to 600 kg/m3. The calculation showed that during the heating period the coordinate of flatness of possible condensation in sandless expanded clay concrete, measured from the inner surface of the wall moves from 0.444 m to 0.5 m. The made assessment of moisture accumulation in the considered outer wall, both for the annual period of operation of the building, and for the period of months with negative temperatures, showed compliance with the regulatory requirements for heated rooms.
Degradation of wooden products used in non-ventilated flat roofs
Authors: Juras P
Published: February 2021

In the recent years, the amount of flat roofs with load bearing structure from wood in Slovakia increases. This is caused by the costs and the effort to maximize the speed of built. Using the wood rafter in the flat roofs cause problem of using an organic material between two vapor tight layers, from interior a vapor barrier and from outside the roofing membrane. Additional, also oriented strand boards are also used instead of wooden boards. These are used either in condensations zones of the roofs or direct under the roofing membrane. This creates degradation of the material because of use in the humid environment in very short time. This paper briefly describes the state-of-art situation in Slovakia with some examples from the buildings and the numerical evaluation of the problem.
Accumulation of damage in reinforced concrete elements under cyclic loads
Authors: Mkrtychev O , Lokhova E
Published: February 2021

The article presents the results of research on the behavior of a frame structure in a reinforced concrete building with a full rigid frame under cyclic load typical for strong earthquakes. When creating a finite element model for the research, the models of materials were used that take into account the nonlinear nature of the structure behavior, as well as the accumulation of damage under cyclic loads. The calculation was carried out by a direct dynamic method using explicit schemes for integrating the equations of motion in the multipurpose finite element software package LS-DYNA.
Theoretical-experimental analysis of selected passive timber house wall
Authors: Michálková D , Ďurica P
Published: February 2021

The advancing times and legislation require constant research of new progressive building envelope structures. Walls based on wooden material are perspective in this regard. These are capable of elimination the wall thickness while providing the required thermal resistance. The pavilion research of KPSU UNIZA laboratory includes this kind of wall structures intended for passive wooden houses. This paper deals with one of the researched wall assemblies in the annual operation. The measurements show that such a construction is suitable for near to zero energy buildings. It also points out that the correct design can eliminate thermal bridges in the area of the load-bearing wooden studs.
Identification of the collapse of the load-bearing facade cladding system of a building
Authors: Papán D , Papánová Z , Ščotka M
Published: February 2021

The aim of paper is to show how one structural fail can cause collapse of cladding system. This cladding system was one of most popular for use about 40 years ago for civic amenities buildings. The simplified theoretical approach for the collapse system reason is verified by modern FEM calculation. The results of investigation contain in situ inspections and measures on specimens. The main result of research is to amplify interest to older facades and its maintained and inspections.
Experimental studies of wind impact on religious buildings
Authors: Poddaeva O I , Fedosova A N , Gribach J S
Published: February 2021

This article is devoted to the description of experimental studies of wind impact on a religious temple in compliance with religious purposes. Studies of aerodynamic characteristics should be carried out using experimental methods for each Orthodox church individually. In the first chapter, the authors describe the specifics of the design of religious buildings, in the type of design of Orthodox churches. In the second chapter, brief information on the conduct of experimental studies of wind impact on the basis of NRU MGSU is launched. In the third chapter, a description of the experimental study of the wind effect on the Orthodox church, created in the Moscow region. Conclusions regarding this study.
Interaction of compressible barrette with surrounding soil and raft
Authors: Ter-Martirosyan Z G , Hung Dam Huu
Published: February 2021

The statement and analytical solution are handled simultaneously with the comparison with the results gained by the numerical method for addressing the problem of quantifying the stress-strain state (SSS) of a multi-layer soil cell consisting of a barrette interacting with the raft-plate. The solution to the assigned problem is considered by the authors for two cases, without and taking into account the compressibility of the underlying soil layer. In the first case, when the underlying soil layer is non-compressive, the formulas are formed in order to determine the SSS in the body of the barrette with the surrounding soil and the equivalent deformation modulus of the barrette-raft-surrounding soil system, so that engineers can absolutely estimate the bearing capacity of the underlying soil under the heel of barrettes. The second case, when the compressibility of the underlying soil layer is taken into account, the solution to the assigned problem is found by means of establishing and solving differential equations of the second order. As a result of the approach above, the formulas for determining the SSS in the body of the barrette are confirmed and the formulas for estimating the settlement of the raft and the equivalent deformation modulus for the barrette-raft-surrounding soil system are obtained. It is noted that taking into account the downward movement of the compressible barrette into the underlying soil layer lead to the decrease in the equivalent deformation modulus of the system.
Predicting the settlement of foundation bases taking into account induced anisotropy
Authors: Ter-Martirosyan Z G , Ter-Martirosyan A Z , Luzin I N
Published: February 2021

This article is devoted to the quantitative assessment of the stress-strain state of finite width foundations, taking into account their induced anisotropy. The article discusses the stress-strain state of a homogeneous base, which acquires the property of deformation inhomogeneity E(x, y, z) under the influence of an external load, due in the general case to a nonlinear dependence of stresses and deformations of the form εm
= σ
m
/K(σ
m
, τ
i
) and γi
= τ
i
/G(σ
m
, τ
i
), where εm
and γi
are volume and shear deformations, and σ
m
are τ
i
the average stress and intensity of shear stresses at each point of the base, K and G are modules of volume and shear deformation. As an example, we consider the stress-strain state of the foundation under the influence of a distributed load p=const along the strip b= 2a (plane deformation). To calculate the settlement with a nonlinear dependences εm
– σ
m
and γi
– τ
i
, it is proposed to use the experimental curves K – σ
m
and G – τ
i
. For the case of the absence of deformation inhomogeneity, when K and G are constant, an analytical solution of the problem is given for the vertical line x=0 under conditions of compression. For this case, a closed solution is obtained, according to which the settlement depends nonlinearly on the width of the loading band b=2a.
Numerical modeling of freezing of structural objects in transition zones of railways
Authors: Hodás S , Pultznerová A
Published: February 2021

The structure of the transition zone of the railway formation is composed of layered materials built into it, which must be resistant to adverse winter climatic conditions characteristic for the region. Among the most dangerous factors is the freezing of these materials and therefore the increased resistance to freezing in winter period is required. By this damage, change of their internal structures and material-technical characteristics can occur. For example, as a consequence of freezing, the structure may be affected by the consequent reduction of resistance of these layers to traffic load (axle loads, deformation modules of the individual layers, etc.). Special construction structures are also designed in the track and the paper is dedicated to transition zone, i.e. reinforced concrete tub as an intermediate element in changing the types of railway formation (the area between the slab track and the continuous track bed). In the experiments using the numerical models, the depth of freezing of the structural objects in the transition zones of the tracks is analyzed, i.e. the zero isotherm height position for 0 °C in the railway structure is determined and compared with respect to the bottom surface of the concrete tub as well as the FPL (frost protection layer) in the continuous track bed, subsequently the design of the objects may be modified.
Preliminary results of geodetic diagnostics of transition areas of ballastless track
Authors: Ižvoltová J , Chromčák J , Pisca P
Published: February 2021

Construction of ballastless track is usually used in high-speed railway, which is suffered by high traffic load. The main reason is to reduce the maintenance costs of the railway line, although the initial costs of its construction are incomparably higher than with the classic construction. From the point of view of long term deformation analysis of railway track, the critical point of such the type of the construction seems to be the place of its completion and transition to the classical the railway superstructure. In terms of dynamic effects, it is a place with a change in stiffness and therefore a special attention is paid to its diagnostics.
The role of underground urbanization in Samara city geological processes
Authors: Vasilieva D , Maltsev A , Baranova M
Published: February 2021

In all largest cities due to lack of territory there is an intensification of underground space use - underground urbanization. It allows finding solutions to transport and environmental problems while preserving the unique appearance of the city’s historical cents. However, the process of underground space development leads to activation of some exogenous processes, which may lead to negative consequences. More than one million people live in Samara city, subway line is built, there are subway objects of industrial and defense importance (bunkers) reaching considerable depth. Active underground construction leads to strengthening of geological processes (weathering, karst formation, suffosia, etc.), change of strength properties of rocks, violation of natural hydrological regime of the territory. By the example of Samara, stages of underground urbanization of the city were studied and its influence on geological processes was considered. Results of studying existing use of city underground space are described. Taking into account geological and geomorphological regionalization of the city, the areas, which underground space development is the most undesirable, were identified.
Diagnostics data in the framework of railway tracks maintenance
Authors: Šestáková J , Pultznerová A
Published: February 2021

Determining the requirement and location and deciding on the time and sources of repair action is a difficult process, influenced by requirements on cost minimization and operational constraints. The particular sections of the railway track react differently to traffic and non-traffic loads, which implies the need to determine the format of development of structural quality indicators and decision-making is based on a large amount of technical and economic information, the interconnection of which is determined by the infrastructure manager. The decision-making process on repair work in the railway infrastructure management system is therefore based on the analysis of diagnostic data, technical, technological, environmental, and economic information, or the personal professional experience of the staff of the infrastructure manager. Understanding the causes of the structure’s behaviour in this process leads to the identification of its weaknesses and the ability to predict its behaviour, which allows for timely planning and accurate targeting of adequate repair work to minimize the occurrence of structural faults.
The cost of repairing damage caused by the inadequate demolition of walls in a multi-family building
Authors: Sawicki M , Szóstak M
Published: February 2021

The article analyses the cost aspects related to the inappropriate demolition of interior walls in a multi-family building in Wroclaw. As a result of demolition and dismantle works on the ground floor of a multi-family building, which was erected using traditional masonry technology, the structural elements on the upper floors were damaged. The expertise report and performed tests confirmed the cause of damage, and the condition of the structure, resulting from the conducted works, was analysed. Recommendations for repairing the structure, and an analysis of the costs associated with the repair were also specified.
New flame-retardant composition for lowering contribution of expanded poly styrene to the propagation of fire
Authors: Mochalov A M , Akulova M V , Sokolova J A , Sokolova A G
Published: February 2021

Despite the major advances in ensuring fire safety of buildings and structures, fire risks still represent the serious issue not only on the territory of the Russian Federation but on the global basis. Presently, while erecting buildings and structures focused attention is given to lowering material consumption and reducing construction time. This is achieved by means of application of lightweight building envelopes with efficient insulators. For the most part, foam poly styrene plates are used as an insulator. Expanded or foam poly styrene has low coefficient of heat conductivity, high acoustic isolation, long-term durability, moisture resistance, and is characterized by ease of installation. However, application of foam poly styrene has constrains due to its high contribution to the propagation of fire.

In the present paper, the authors proposed new flame-retardant composition on the base of organo-siloxanes, which inhibits combustion initiating of foam poly styrene and constrains fire propagation when applied on the surface of foam poly styrene plates.