Moscow State University of Civil Engineering

This paper reviews the recent research in the application of fractional calculus in the models of linear viscoelasticity utilized in dynamic problems of mechanics of solids. The brief historical survey reflecting the contribution of Soviet mechanicians in the development of hereditary mechanics is provided. Different fractional derivative models of viscoelastic materials have been analyzed, among them those considering the bulk relaxation. It is shown that the models with time-dependent Poisson’s operators allow one to describe the properties of viscoelastic auxetics, i.e. materials with negative Poisson’s ratios. A companion article will review boundary-value dynamic problems utilizing the rheological models considered in the given paper and will provide a critical estimation of the results obtained in the field during last decade in the light of new apprehensions of the role and place of the fractional calculus in engineering practice.

Human immunodeficiency virus type 1 (HIV) gag/pol and env mRNAs contain cis-acting regulatory elements (INS) that impair stability, nucleocytoplasmic transport, and translation by unknown mechanisms. This downregulation can be counteracted by the viral Rev protein, resulting in efficient export and expression of these mRNAs. Here, we show that the INS region in HIV-1 gag mRNA is a high-affinity ligand of p54nrb/PSF, a heterodimeric transcription/splicing factor. Both subunits bound INS RNA in vitro with similar affinity and specificity. Using an INS-containing subgenomic gag mRNA, we show that it specifically associated with p54nrb in vivo and that PSF inhibited its expression, acting via INS. Studying the authentic HIV-1 mRNAs produced from an infectious molecular clone, we found that PSF affected specifically the INS-containing, Rev-dependent transcripts encoding Gag-Pol and Env. Both subunits contained nuclear export and nuclear retention signals, whereas p54nrb was continuously exported from the nucleus and associated with INS-containing mRNA in the cytoplasm, suggesting its additional role at late steps of mRNA metabolism. Thus, p54nrb and PSF have properties of key factors mediating INS function and likely define a novel mRNA regulatory pathway that is hijacked by HIV-1.

Pre-harvest prediction of a crop yield may prevent a disastrous situation and help decision-makers to apply more reliable and accurate strategies regarding food security. Remote sensing has numerous returns in the area of crop monitoring and yield prediction which are closely related to differences in soil, climate, and any biophysical and biochemical changes. Different remote techniques could be used for crop monitoring and yield prediction including multi and hyper spectral data, radar and lidar imagery.This study reviews the potentialities, advantages and disadvantages of each technique and the applicability of these techniques under different agricultural conditions. It also shows the different methods in which these techniques could be used efficiently. In addition, the study expects future scenarios of remote sensing applications in vegetation monitoring and the ways to overcome any obstacles that may face this work.It was found that using satellite data with high spthermaatial resolution are still the most powerful method to be used for crop monitoring and to monitor crop parameters. Assessment of crop spectroscopic parameters through field or laboratory devices could be used to identify and quantify many crop biochemical and biophysical parameters. They could be also used as early indicators of plant infections; however, these techniques are not efficient for crop monitoring over large areas.

“Smart” buildings is an emerging technology. Very often a building “intelligence” is confused with just a building automation. This paper explores distinctive features of “smart” buildings. It was figured out that a formal definition and a quantitative measure of a building “intelligence” do exist. However, due to non-deterministic nature of Artificial Intelligence, a simulation of building operations is required to calculate Building Intelligence Quotient.

The results of studying the morphological peculiarities of polycrystalline CdS1−xSex films, obtained by screen printing, with well-formed grain boundaries of high structural quality are presented here. The developed method for screen printing provides the formation of polycrystalline films of a specified area per cycle, provided that there is a possibility for varying their thickness from tens of microns to units, which allows reducing the solar cell’s thickness and facilitating the process of its connection with the substrate. Therefore, the application of the films to a sitall substrate by screen printing contributes to reducing the product weight and facilitating the process of joining sheet materials intended for solar panels, namely attaching the lasing element to the substrate. The purpose of this work is to study the morphological peculiarities of polycrystalline CdS1−xSex films obtained by an optimized screen-printing method and to create a model of their formation process. The structural and morphological peculiarities of the samples were studied using electron microscopy, AFM, XPA, and XFS. As a result of the work, based on the obtained experimental data, a model of the film formation process was developed. The model validity is justified by the conformity of the data of the experiment performed on its basis.

Рецензируемые научные журналы МГОУ. Журналы МГОУ входящие в перечень ВАК: География, История, Международные отношения, Политология, Лингвистика, Педагогика, Психология, Филология, Физика-математика, Философия, Экономика, Юриспруденция

In this research, we present an efficient implementation of machine learning (ML) models that forecast the mechanical properties of basalt fiber-reinforced high-performance concrete (BFHPC). The objective of the present study was to predict compressive, flexural, and tensile strengths of BFHPC through ML techniques and propose some correlations between these properties. Moreover, the modulus of elasticity (ME) values and compressive stress–strain curves were simulated using ML techniques. In this regard, three predictive algorithms, including linear regression (LR), support vector regression (SVR), and polynomial regression (PR), were considered. LR, SVR, and PR were utilized to forecast the compressive, flexural, and tensile strengths of BFHPC, and the PR technique was employed to simulate the compressive stress–strain curves. The performance of the models was also determined by the coefficient of determination (R2), mean absolute errors (MAE), and root mean square errors (RMSE). According to the obtained values of R2, MAE, and RMSE, the performance of PR was better than other types of algorithms in estimating the compressive, tensile, and flexural strengths. For example, R2 values were 0.99, 0.94, and 0.98 in predicting the compressive, flexural, and tensile strengths using PR, respectively. This shows the higher accuracy and reliability of the PR technique compared with other predictive algorithms. Finally, we concluded that ML techniques can be appropriately applied to assess the mechanical characteristics of BFHPC.

Carbon materials are promising for use as electrodes for supercapacitors and lithium–ion batteries due to a number of properties, such as non-toxicity, high specific surface area, good electronic conductivity, chemical inertness, and a wide operating temperature range. Carbon-based electrodes, with their characteristic high specific power and good cyclic stability, can be used for a new generation of consumer electronics, biomedical devices and hybrid electric vehicles. However, most carbon materials, due to their low electrical conductivity and insufficient diffusion of electrolyte ions in complex micropores, have energy density limitations in these devices due to insufficient number of pores for electrolyte diffusion. This work focuses on the optimization of a hybrid material based on porous carbon and carbon nanotubes by mechanical mixing. The purpose of this work is to gain new knowledge about the effect of hybrid material composition on its specific capacitance. The material for the study is taken on the basis of porous carbon and carbon nanotubes. Electrodes made of this hybrid material were taken as an object of research. Porous carbon or nitrogen-containing porous carbon (combined with single-, double-, or multi-layer carbon nanotubes (single-layer carbon nanotubes, bilayer carbon nanotubes or multilayer carbon nanotubes) were used to create the hybrid material. The effect of catalytic chemical vapor deposition synthesis parameters, such as flow rate and methane-to-hydrogen ratio, as well as the type of catalytic system on the multilayer carbon nanotubes structure was investigated. Two types of catalysts based on Mo12O28 (μ2-OH)12{Co(H2O)3}4 were prepared for the synthesis of multilayer carbon nanotubes by precipitation and combustion. The resulting carbon materials were tested as electrodes for supercapacitors and lithium ion intercalation. Electrodes based on nitrogen-containing porous carbon/carbon nanotubes 95:5% were found to be the most efficient compared to nitrogen-doped porous carbon by 10%. Carbon nanotubes, bilayer carbon nanotubes and multilayer carbon nanotubes synthesized using the catalyst obtained by deposition were selected as additives for the hybrid material. The hybrid materials were obtained by mechanical mixing and dispersion in an aqueous solution followed by lyophilization to remove water. When optimizing the ratio of the hybrid material components, the most effective porous carbon:carbon nanotubes component ratio was determined.

The article considers the environmental economic model of risk management and the costs associated with them. In the field of eco-friendly construction and labor safety, it is customary to allocate occupational hazards and hazards, expressed by quantitative or qualitative parameters of occupational risk. Risk management or environmental risk means the recognition and analysis of risks, the development and implementation of management decisions to reduce the likelihood of adverse situations, as well as the possible reduction of material or other losses. Risk management helps to get out of the zone of uncertainty into a situation with more or less predictable results. The methodology for applying the environmental economic model under consideration is a cyclic order of performing interrelated practical actions known as the Deming-Shewhart cycle, which is inextricably linked to the process approach and the quality management system. Synthesis of the principles of the quality management system and mechanisms for managing environmental risks and costs ensures high adaptability to any external and internal stress situations, reveals professional risks in a timely manner, optimizes processes and, as a result, reduces costs.

The article presents the results of the conducted researches on modifying traditional construction materials like cement concrete, anhydrite binders, silicate paint and fire-retardant coating based on liquid glass. Modification was due to multi-walled carbon nanotubes dispersions uniformly distributed in binding matrices while preparing materials, which led to modification of the structure and the properties of materials and products.

The increase in the share of physical and technical processing methods in the arsenal of deburring technologies used in modern production is associated both with the use of difficult-to-machine materials, such as beryllium bronze and the 29 NK alloy, and with the need to solve technological problems for the production of small-sized products with hard-to-reach surfaces. The aim of the study is to improve the processes of blade processing of small-sized parts made of beryllium bronze and the 29 NK alloy to provide rational conditions for thermal pulse deburring. Surface samples were experimentally obtained after turning in different modes on a CITIZEN CINCOM K16E-VII automatic lathe equipped with an Applitec micromechanics tool. The surface quality and burr characteristics were examined using a JEOL JIB-Z4500 electron microscope and a ContourGT-K optical profilometer. The program Statistica 6 allowed processing of the results. The relationship between the parameters of the turning mode and the thickness of the root of the burrs formed on the machined surface, the limitation of which is one of the conditions for the application of the thermal pulse method, was established. The obtained empirical regression dependencies establish a rational range of cutting mode parameters, and the implementation of the formulated recommendations for setting blade modes ensures deburring by the thermal pulse method in compliance with the requirements of drawing under maximum processing performance.

Damage induced in polymer composites by various impacts must be evaluated to predict a component's post-impact strength and residual lifetime, especially when impacts occur in structures related to human safety (in aircraft, for example). X-ray tomography is the conventional standard to study an internal structure with high resolution. However, it is of little use when the impacted area cannot be extracted from a structure. In addition, X-ray tomography is expensive and time-consuming. Recently, we have demonstrated that a kHz-rate laser-ultrasound (LU) scanner is very efficient both for locating large defects and evaluating the material structure. Here, we show that high-quality images of damage produced by the LU scanner in impacted carbon-fiber reinforced polymer (CFRP) composites are similar to those produced by X-ray tomograms; but they can be obtained with only single-sided access to the object under study. Potentially, the LU method can be applied to large components in-situ.

Many methods have been tested and developed all over the world to save water from evaporation process. This paper presents a state-of-art review of published research work in the last 14 years (from 2014 to 2018) in which it was focused on the physical, chemical and biological methods of evaporation reduction from water surfaces. The main characteristics, as well as the advantages and disadvantages of each method are indicated. Among these used techniques for reducing evaporation are physical methods that use floating or suspended covers and can save a large percentage of water (between 70 and 95%). The use of thermal mixing by compressed air seems to be very important for evaporation suppression on deep reservoirs (greater than +18 m). Moreover, currently chemicals are widely used to reduce water evaporation, such as WaterSavr, and can save relatively a small percentage of water (between 20 - 40%). Biological methods such as floating plants, wind breakers and palm fronds can provide a significant decrease in the volume of evaporation but they have some restrictions on their uses.

values data set from PolyAskInG database. The obtained results indicate that pretraining of GCNN on the "synthetic" polymer data set provides MAE which is almost twice as low as that in the case of using the QM9 data set in the pretraining stage (∼41 K). Furthermore, we address the questions associated with the influence of the differences in the size of the experimental and "synthetic" data sets (so-called "reality gap" problem), as well as their chemical composition on the training quality. Our results state the overall priority of using polymer data sets for developing deep neural networks, and GCNN in particular, for efficient prediction of polymer properties. Moreover, our work opens up a challenge for the theoretically supported generation of large "synthetic" data sets of polymer properties for the training of the complex ML models. The proposed methodology is rather versatile and may be generalized for predicting other properties of different polymers and copolymers synthesized through the polycondensation reaction.

Abstract The article investigates one‐dimensional (1‐D) suspension‐colloidal transport of size‐distributed particles with particle attachment. A population balance approach is presented for computing the particle transport and capture by porous media. The occupied area of each attached particle is particle size‐dependent. The main model assumption is the retention rate dependency of the overall vacancy concentration for all particle sizes. For the first time, we derive an exact averaging (upscaling) procedure resulting in a closed system of large‐scale equations for average concentrations of suspended and retained particles and of occupied rock surface area. The resulting large‐scale 3 × 3 system significantly differs from the traditional 2 × 2 deep bed filtration model. However, the traditional model becomes a particular case that corresponds to an equal occupied area for all particles. The averaging yields the appearance of two empirical suspension and site occupation functions, which govern the kinetics of particle retention and site occupation, respectively. One‐dimensional flow problems for the averaged equations are essentially nonlinear. However, they allow for exact solutions. We derive novel exact solutions for three 1‐D problems: continuous injection of particulate colloidal suspension, injection of colloidal suspension bank with particle‐free chase drive, and fines migration induced by high‐rate flows. The analytical model for continuous injection closely matches three series of laboratory tests on nanofluid transport.

Asphalt rubber (AR), which is prepared by blending crumb rubber and bitumen, provides various advantages, including superior rutting resistance, lower road-tire noise and longer service life. However, contractors have expressed concerns regarding its poor storage stability, which in turn limits its wider application. This study aims to address the storage stability concern by incorporating nano-montmorillonite (nanoclay). Three types of nanoclay were dispersed into hot AR binder by high shear blending. The rheological properties of nanoclay-crumb rubber modifier (CRM)-modified bitumen were evaluated through Superpave performance grade (PG) tests and the storage stability was characterized by measuring the difference in softening points or complex moduli at the top and bottom portions of binders after lab-simulated storage. X-ray diffraction (XRD) evaluation was conducted to observe the variation of nanoclay layer gap distance for mechanism investigation. It was found that all selected nanoclays had insignificant effects on workability, rutting and fatigue properties. The layered nanoclay transformed to intercalated or exfoliated structures after interaction with bitumen fractions, providing superior storage stability. Among the three selected nanoclays, pure montmorillonite with Na⁺ inorganic group, which has an intermediate hydrophilic property and middle layer gap, showed the most obvious effect on enhancing the storage stability of AR.

An analysis of the results of rail operation shows that up to a third of all rail breaks in the railway line and up to 12.9% of all withdrawn acute defective rails are associated with welded joints. This is largely explained by the formation of structures with martensite sections in the welded joints of rails and the formation of burns. This work presents the results of studying welded joints, obtained under three welding modes (continuous flash welding, pulsating flash welding and combined flash welding). The conducted studies have shown that the flash welding mode significantly influences both the cooling rate value and the very nature of the thermal cycle of the welded joint as a whole. Changes in the cooling rate under different modes exert a significant influence on the structure and properties of the weld. Resistance welding of rails from the steel grade E76HGF by pulsating flash welding can result in the appearance of needle martensite areas, which is the reason for increased embrittlement of the weld and a decrease in its properties. The conducted field experiments have reliably shown that in the conditions of the combined welding mode it becomes possible to avoid these problems. Moreover, a slight increase in the mechanical properties of the weld in the range of 2–4% has been experimentally recorded, and the destructive load of the welded joint of the rail increases by 2–3% at high values of the bending deflection. In turn, these factors allow a significant reduction in the number of cases of rail welded-joint failures in real conditions of their operation.

We analyze the field in the epicentral zone for the internal Lamb problem of the action of a concentrated force within an elastic half-plane. We compare the solutions obtained using integral representations, geometric-optical methods, and finite-element approximations.

Abstract The article presents data on changes in the main hydraulic parameters of the flow in the hydrological sections of the Amudarya river located in the zone of influence of the Takhiatash and Tuyamuyun reservoirs. It has been established that in recent years an acute water shortage has been observed in the lower reaches of the river during the growing season. In dry years for the Amudarya River, the Takhiatash hydroelectric complex becomes the last section, in some periods there are even no sanitary passes through the hydroelectric complex in the prescribed manner, and as a result, a tense situation is created in the Amudarya delta below the Takhiatash hydroelectric complex. Analysis of the hydrological regime of the river showed that in the lower reaches of the Amudarya on the territory of the Kharezm region and Karakalpakstan, the water regime of the river is very different from the domestic one. The low-water period on the river practically begins in September, as there is a large flow of water in September and October. The waters coming from the upper reaches of the river are retained to fill the Tuyamuyun reservoir. At the same time, the end of the low-water period is actually shifted to the beginning of March, since in March, the work of the water accumulated in the reservoir begins and its supply for flushing irrigation begins. The flood waters entering the Tuyamuyun reservoir are either fully accumulated (if the reservoirs are not filled up to the normal retention level of the NRL) or are very strongly transformed (if the reservoir is filled up to the NRL). Analysis of the dynamics of sediment runoff showed that the amplitudes of fluctuations in sediment runoff over periods have a very wide range of changes. In the initial period of operation of the hydroelectric complex, the sediment runoff mode almost repeats the household mode, that is, the largest runoff occurs during the dry season, but with the lowest solid runoff values on average 3 and 8 (at the Samanbai station) times. For 7 years from 1975 to 1981, the annual flow at the Kipchak gauging station amounted to 41.722 thousand tons, that is, 32% of the annual household regime. The largest annual flow at the Kipchak and Samanbai gauging stations took place in the high-water year 1978 and amounted to 66329 and 57971 thousand tons соответственно. The smallest amount of annual runoff at gauging stations was observed in dry 1981 and amounted to 25074 and 3943 thousand tons. The study of the sediment runoff regime of the Amudarya river during the period of joint operation of the Takhiatash and Tyuyamuyun hydrosystems showed that the amount of solid runoff entering the zone of influence of the Takhiatash hydroelectric complex significantly decreased due to a sharp decrease in water discharge under the influence of regulation and low water. At the same time, as the analysis of field studies has shown, despite their relatively small number, accumulation of sediments is observed in the pays of the hydroelectric complex, that is, silting occurs. The amount of sediment siltation in the area of the Takhiatash hydroelectric complex varies depending on the water content of the year and the operating mode of the Takhiatash hydroelectric complex. Analysis of the alluvial regime shows that during the period of operation of the hydroelectric complex, depending on the hydrological regime of the river and the regime of the water level in front of the dam, the clarification of the flow occurs in April, May, June and August. The seasonally average clarification of the flow within the upper pool ranges from 10 to 40%, and in some months, at levels close to the NSP, reaches 90%, that is, the upper pool of the node turns into a kind of settling tank. The composition of suspended sediments of the Amudarya varies both in time and along the length of the river, but particles smaller than 0.25 mm remain predominant. Particles larger than 0.25 mm are found only in the upper areas and in an amount of no more than 3 - 4%. During the flood period, along the entire length of the river, the percentage of fines content increases in comparison with the low-water period.

The paper offers update information on wastewater removal from phosphates. The writers describe the most commonly used efficient methods to remove phosphates from wastewater based on principles of biology, chemistry, physical chemistry and biological chemistry. The paper presents the results of research on phosphate-removing wastewater treatment methods using iron-bearing reinforced charge material.