bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydro-mechanical modeling of a vegetated slope subjected to rainfall
Authors: Sadeghi Hamed , Yazdani Bene Kohal Farshad , Gholami Mostafa , Alipanahi Pouya , Song Dongri
Published: April 2023

Shallow landslides triggered by heavy rainfalls have caused casualties and economic losses to domestic infrastructures and industries worldwide. Rainfall mainly reduces the soil matric suction and the shear resistance, resulting in shallow landslides. Vegetation is an eco-friendly and cost-effective method for stabilizing slopes prone to shallow landslides. This research aims to investigate the hydrological and mechanical effects of vegetation on slope stability through a numerical study approach. Vegetated and bare slopes were subjected to a recorded climate condition and two rainfall scenarios of high intensity (HI) and low intensity (LI). Matric suction and factor of safety of vegetated and bare slopes subjected to rainfall were investigated. The matric suction of the vegetated slope at the surface was approximately four times greater than the bare slope after the HI scenario. However, the matric suction is about three times greater in the LI scenario. The results indicate that planting on slopes would reduce the vulnerability of bare slopes to the HI rainfall due to the higher matric suction and additional cohesion induced by the root system. These findings suggest that using vegetation in Rasht, Iran, where the climate data were collected, has considerable potential for stabilizing slopes.
Gas transport in a binary bentonite mixture used in sealing systems
Authors: Mesa-Alcantara Arisleidy , Romero Enrique , Mokni Nadia
Published: April 2023

Binary mixtures composed of 80% of high-density pellets and 20% of granular bentonite at hygroscopic water content are currently considered for use in vertical sealing systems for the deep and longterm disposal of radioactive wastes. By pouring the dry components without compaction, the mixturedisplays a dry density of around 1.49 Mg/m3. However, these sealing systems are subjected to long-term hydrations from the surrounding formations with the possibility of having zones with entrapped and generated gas that makes it challenging to display a homogeneous saturation of the seal. Therefore, gas transport through these bentonite-based sealing materials at different degrees of saturation is a crucial issue. Hence, several oedometer tests have been conducted to evaluate the impact of gas injection on this mixture at different degrees of saturation and constant pouring dry density. These gas injection/dissipation tests were performed at constant vertical stress or constant volume conditions. The results provided the variation of the effective gas permeability at different degrees of saturation and the gas breakthrough pressure aftersaturation. Furthermore, these gas transport results were interpreted with a microstructural study of the mixture focusing on the volumetric filling of the inter-pellet porosity.
Experimental and numerical study on homogenisation of BCV bentonite using dual density samples
Authors: Najser Jan , Mašín David
Published: April 2023

Homogenisation of bentonite materials is an essential feature for its sealing function in radioactive waste repositories. Presented study is focused on the laboratory investigation of the homogenisation of Czech BCV bentonite (Ca/Mg type). The experimental program included measurementof the swelling pressures of single-density and dual-density samples of the compacted bentonite, where dualdensity sample is composed of two layers compacted to two different dry densities. Tests were performed in constant volume cells, which allowed measurement of swelling pressure evolution. Dual-density tests included two identical samples saturated from different sides. Homogenisation was investigated through the determination of the final density distribution in a vertical profile from the post-mortem analysis. Further,the laboratory experiments were simulated by means of a thermo-hydro-mechanical hypoplastic model for bentonite implemented in the SIFEL coupled finite element code. It was found that swelling pressures developed by dual-density samples corresponded well to swelling pressures developed by single densitysamples of equivalent dry densities, while its time-evolution was different. Dual density samples also revealed very good level of density homogenisation after the test. The first observation (swelling pressure along with its temporal evolution) was predicted well by the model, which however underestimated the level of dry density homogenisation.
On the thermal hydro mechanical chemical behavior of bentonite sand mixture
Authors: Nishimura Tomoyoshi
Published: April 2023

The concept to high-level radioactive waste (HLW) repository generally involves anengineering-artificial barrier system, in which hardly compacted bentonite sand mixture blocks are placed carefully around the waste canister, and the canister is of stiffness in the design. Placed the bentonite sandmixture blocks, gradually receive hydration due to groundwater. Thermal-hydraulic-mechanical-chemical phenomena of compacted bentonite sand mixture after wetting, suction change and thermal effort are a critical parameter for buffered system This study proposes the influence of suction, relative humidity and thermal effort in thermal-hydraulic on deformation properties and mechanical properties for bentonite-sand mixture. A series of testing programs are prepared such as calibration test for changing of relative humiditywith temperatures, measurement of volume change involving heating and changing of suction, determination of unconfined compressive strength, for thermal performance triaxial compression tests for both unsaturated bentonite sand mixture and saturated bentonite sand mixture. The obtained results are further interesting, and summary provide as following. To suction increment incorporation with thermal heating produce induces obviously shrinkage of the bentonite sand mixture, and lead the decrement of strength. Elevated temperature confirm further reduction for maximum deviator stress using a developed triaxial compression apparatus that is regardless of unsaturated condition and saturated condition.
Microstructure and hydro-mechanical behaviour of compacted granular bentonite
Authors: Zeng Hao , Gonzalez-Blanco Laura , Romero Enrique , Fraccica Alessandro
Published: April 2023

In recent years, granular bentonite GB has become a reference material since it facilitates the backfilling operation due to high-density compacted granules with extended grain size distribution(maximum sizes around 10 mm). This investigation explores the initial microstructure of MX80-type GB and the hydro-mechanical HM response observed at the phenomenological scale. Samples were statically compacted at a fixed dry density (1.55 Mg/m3 ), encompassing dry and wet sides of the optimum. Themicrostructural study was performed using a combination of X-ray micro-computed tomography and mercury intrusion porosimetry. The results indicate that the pore size density function of compacted GB can be simplified as a double-porosity network with micropores (intra-granular/aggregate pores) and macropores(inter-granular/aggregate pores). Compacting at the dry side increases macropores, making the sample more compressible on loading under as-compacted states despite the higher matric suction. The time evolution of the swelling pressure displays a double-peak pattern attributed to the particular microstructure of the samples. Moreover, the initial microstructure does not significantly influence the water retention properties without a marked hysteresis in the high-suction range under confined wetting/drying cycles. This work’s outcomes highlight the microstructure’s significance in the HM behaviour of compacted GB and provide further insight into the geotechnical properties of this material.
Numerical integration of the Glasgow Coupled Model (GCM)
Authors: Lloret-Cabot Martí , Wheeler Simon J. , Gens Antonio
Published: April 2023

This paper presents the derivation of the incremental constitutive relations of the Glasgow Coupled Model (GCM), an established elasto-plastic model for unsaturated soils intended to represent their mechanical and water retention behaviour. The set of incremental equations derived defines an initial value problem (IVP) that needs to be solved at each integration step once the initial (or previous) state and theincrements of suction and strain are known. To solve this IVP effectively, a small reformulation of the GCM (not involving any modification of the model, but simply presenting it differently) has been adopted withthe aim to facilitate the development of a robust algorithm capable to identify unambiguously the correct model response activated by a given stress path (i.e. elastic, mechanical yielding, water retention yielding or simultaneous mechanical and water retention yielding). Subsequent to the description of this algorithm, the paper presents an explicit substepping integration scheme with automatic error control able to integrate the incremental constitutive equations of the model for each possible response, including unsaturated and saturated conditions. The numerical capabilities of the substepping scheme in terms of accuracy and efficiency are then demonstrated in the context of the performance maps proposed originally for saturated soil models.
Assessment of tunnels stability in the Maya archaeological area of Copán, Honduras
Authors: Bilotta Emilio , Flora Alessandro , Lourenço Paulo , Pires Felipe
Published: April 2023

Copan is an important heritage site known by its preserved Maya ruins and recognized by UNESCO as a World Heritage Property since 1980. To investigate and understand the site development, extensive archaeological tunnels were excavated in the earthen fills of the temples in the twentieth century.Archaeologists found a series of superimposed temples, built one upon another, in a very complex chronological sequence and spatial disposition. Even though the tunnels were initially excavated in the earthen fill without putting in place any supporting structure, masonry lining was applied in parts of the unnels years after they were excavated, in areas that suffered local collapses. Thick walls were built, forming tunnels about 1.0 m wide and 2.0 to 3.0 m high. The excavated soil is unsaturated, and thus has a strength depending on its water content and suction. Since most of the observed collapses take place during raining events, the effect of the change of the saturation degree on tunnels stability was investigated with numerical analyses. As typical in numerical simulations, the positive effects of desaturation were considered in this work through a simplified approach, introducing an ‘apparent cohesion’ depending on the soil water content. The outcomes indicate that in order to ensure sufficient safety margins in the tunnels, water content within the soil mass close to the tunnels, in critical sections, should be carefully monitored, and drainage in the lined sections should be ensured to avoid direct water pressure on the lining.
An experimental methodology to assess the impact of desaturation on gas diffusion in clay based materials
Authors: Gowrishankar Aadithya , Jacops Elke , Maes Norbert , Verboven Pieter , Janssen Hans
Published: April 2023

The transport of gas in clay-based materials is dominated by diffusion. SCK CEN has studied and recorded an extensive data set of diffusion coefficients of gases in various saturated clays (Boom Clay, Opalinus Clay, Callovo-Oxfordian claystone and bentonites) used in Europe as host formations or in engineered barrier systems in the context of deep geological disposal of high and intermediate level nuclear wastes. However, partially saturated conditions may exist during the life cycle of a radioactive waste repository. The current study aims at establishing an experimental method to measure the diffusion coefficients of various gases in partially saturated clay-based materials by means of double through diffusion tests (cross diffusion of gases across the porous sample, driven by concentration gradients) and to assess the impact of desaturation on gas diffusivity. Historically, gas diffusion measurements have been performed under dissolved conditions with continuous water and dissolved gas flow around the clay sample. However, since the saturation degree of the sample has to be constant, a novel setup has been designed and optimized to operate under a pure gas phase under controlled relative humidity (RH). The experimental concept consists of cross diffusion of gas mixtures from two reservoirs at a fixed relative humidity on either side of the sample cell, namely, the upstream and downstream reservoirs. The RH is controlled using the same saturated salt solutions in both reservoirs. During the experiment, gases will diffuse from the upstream to the downstream reservoir. By measuring the change in gas composition in the downstream reservoir with a gas analyzer equipped with a mass spectrometer (which expresses the gas composition in terms of partial pressure), the gas flux and hence the diffusion coefficient is estimated by applying steady state Fick’s first law. The experimental methodology has been validated by performing an experiment on a sandy-clay sample of known petrophysical properties, at full saturation.
The effect of microbes on the stability of an unsaturated tropical slope
Authors: de Carvalho Faria Lima Lopes Bruna
Published: April 2023

Conventional geotechnical practice considers that soil is an inert construction material and its engineering properties do not change with time. However, soil is a living ecosystem, and its engineering properties naturally change as a stable ecological system is gradually established following initial construction. Over the last few decades, researchers started exploring a way to engineer some microorganisms’ activities in order to solve problems in geotechnical engineering. This paper assesses the effect of a biostimulated Microbial Induced Calcite Precipitation (MICP) on the stability of an unsaturated tropical slope. For that, data from an experimental characterisation study carried out for a tropical soil was used. For the assessment of the stability of the slope, a critical rainfall for the region was considered and the pore water pressure distribution was obtained. The stability of the slope was assessed using a ‘simplified’ shear strength criterion formulated in terms of unsaturated cohesion. Results show that the MICP treatment contributes to the stability of the slope. This positive contribution is more significant than the contribution of suction towards the stability of the slope.
Numerical investigation on three-phase flow in unsaturated soil considering porosity effects on soil hydraulic properties
Authors: Yu Jiaren , Zhou Chao
Published: April 2023

Ground contamination by mineral oil and hydrocarbons is a serious problem worldwide. These non-aqueous phase liquid (NAPL) represents long-term contamination sources to the soil, groundwater, and ecological environment. In the existing numerical simulation models utilized in most simulation programs, the relation between porosity and the hydraulic properties of unsaturated soils is highly simplified as nonlinear. However, the nonlinear porosity effect on soil permeability and the capillary pressures cannot be well considered in this way. In this study, a new mathematical model has been developed to incorporate porosity effects into the hydraulic properties of soils, including the retention behaviour and permeability function of NAPL and water. This model has been implemented in MATLAB using the finite difference method and verified by a centrifuge test about NAPL infiltration. Then, a series of parametric studies will be carried out to investigate the multi-phase flow under a continuously leaking NAPL source. The influence of porosity magnitude and distribution will be investigated. Special attention will be paid to the influence of porosity distribution by soil consolidation on NAPL flow, which is often ignored by the existing simulations using constant porosity values.
UnSaLuDo: The development of an educational board game on unsaturated soil mechanics
Authors: Froes Cardoso Gustavo Augusto , Ramos Chrusciak Mariana , Cordao-Neto Manoel Porfirio , de Carvalho Faria Lima Lopes Bruna
Published: April 2023

Non-conventional tools of teaching are effective in delivering deep learning of scientific facts as well as skills associated with scientific disciplines. A well-known method to promote student engagement and learning in general is the use of games in classrooms. Games can provide a flexible option that could engage students, create active learning experiences, and enable them to experiment in safe playful environments. This paper presents UnSaLuDo, a board game developed by the GeoFUN group. The goal was to develop a tool that enables students to experience fun and integrational activities in a classroom setting while learning complex scientific targeted threshold concepts related to unsaturated soil mechanics. The topics covered by UnSaLuDo included fundamental concepts of cohesion and adhesion in liquids, surface tension, contact angle and capillary rise; water retention and water flow in unsaturated soils; volume change, deformation, and shear strength of unsaturated soils. This paper provides background information on the motivation for the development of the board game and an overview of the topics covered. The paper also presents all the components of the board game developed and suggests approaches for how it can be incorporated into geotechnics courses.
A microstructure-based procedure to simulate the effect of wetting-drying cycles on the soil water retention curve
Authors: Vidler Andrew , Buzzi Olivier , Fityus Stephen
Published: April 2023

Analysing unsaturated soil response often requires the soil-water-retention-curve (SWRC). The SWRC depends upon the soil microstructure, which evolves with hydromechanical loading such as in-situ exposure to wetting-drying cycles. If in-situ response is of interest and studied in the laboratory, it is essential specimens have a structure representative of in-situ conditions. Simulating wetting-drying cycles in the laboratory is possible albeit time-consuming and a faster alternative procedure would be preferred, which is the focus of this paper. Mixtures of two soils were prepared in the laboratory by either: exposure to three simulated wetting-drying cycles, or one of two compaction approaches. The microstructure and drying-path SWRC of the specimens prepared with each method were measured. Most of the compacted specimens achieved similar pore size distributions to the cycled samples though the outcomes in terms of achieving a target SWRC, which was the objective of the study, are mixed. The SWRCs of most compacted samples had similar gravimetric water contents yet significantly higher saturation degree at every suction measured. This is explained by the compacted samples containing less macro pores than cycled samples. The compaction procedure, designed to produce specimens having a SWRC similar to that of cycled materials, seems promising but needs modification.
Soil water retention curve of silty sand – experimental investigation using different laboratory methods
Authors: Matziaris Vasileios , Osinski Piotr , Vimalan Jeganathan , Koda Eugeniusz
Published: April 2023

Most of the infrastructure investments and earthworks not requiring deep foundations are usually designed in the vadose zone to avoid excessive groundwater-structure interactions. The mechanical behaviour of soil material, under partially saturated conditions, is greatly influenced by pore-water tension, known as soil suction, and the characteristics of the Soil Water Retention Curve (SWRC). In the present paper, the SWRC of a silty sand was determined using two different experimental methods. In the first method, a modified pore water pressure transducer was used for suction monitoring, while the specimen was allowed to change its moisture content by natural evaporation. For the second method, a modified consolidation cell fitted with a high air entry value ceramic disc on the base pedestal was used. Suction was applied using the axis translation technique by utilising pore air and pore water pressure controllers, while moisture was monitored using a volumetric measurement system. Through the determination of the SWRC for the silty sand, this paper intends to compare the abovementioned testing methods basedon the produced SWRCs and to reveal advantages and limitations.
Influence of speed of rail flaw detection on the reliability of its results
Authors: Davydkin A.V. , Dymkin G.Ya. , Konshina V.N.
Published: April 2023

The system of non-destructive testing of rails during their operation on the railroad network of the Russian Federation is based on the use of removable and mobile means of flaw detection. The increase in the volume of control by mobile means in recent years is explained by their higher productivity due to the higher speed of control. But the increase in the speed of control inevitably leads to the loss of acoustic contact and missing defects.
Modeling frame of a diesel locomotive bogie in solidworks software
Authors: Grischenko A. , Shrajber M. , Ivanov V.
Published: April 2023

The article considers the possibility of using the finite element method for strength calculations of nodes and parts of modern locomotives. There are examples of solid-state models construction of bogie frames in SolidWorks software package. Developed finite-element models allow determining the tense-strained state of the elements of the crew part of locomotives. The final outcome of modeling is the construction of stress distribution diagrams in the locomotive bogie frame. The data obtained as a result of finite-element modeling can be recommended for use when creating new modern units of locomotives as well as for modernizing and increasing the reliability of existing.
Application of ballastless construction of the railroad track in the Arctic zone
Authors: Dudkin Evgeni , Sultanov Nariman , Malakhov Maksim
Published: April 2023

Abstract: the article provides a calculation justification of the proposed railway structure on a reinforced concrete sleeper-free base, for which an analysis of the existing methodology for calculating the railway track for strength is carried out, according to which for a railway track on a sleeper-free base, dynamic loads acting from the rolling stock on the track are determined. The analysis of the applied sleeper-less structures of the railway track and the results of measurements of emerging stresses in the substructure, the measured depth of the core are carried out. Using the previously obtained results of studies of the depth of the core, the justification of the required height of the embankment and the calculation of the parameters of the subplate base is carried out. Next, the finite element method calculates the bending stresses arising in the bearing plate, where the maximum is 1.82 MPa and is compared with the permissible value, which is much greater for a reinforced concrete slab. Also, the result is the obtained elastic vertical movements, which indicate a more uniform distribution of the load from the rolling stock on the roadbed.
Peculiarities of protection of railroad tracks from snow drifts in the arctic zone
Authors: Blazhko L. , Seleznev V.
Published: April 2023

The natural and climatic conditions of Russia's Arctic zone require special designs and technological solutions for railroad operation, due to the simultaneous presence of permafrost soils and gigantic volumes of snow transport. The article talks about the need for theoretical justification of calculation schemes for permafrost processes.
Specifical features of designing of magneticaly levitated transport systems using permanent magnets
Authors: Nikitin Victor , Zimenkova Tatyana , Kazhacheev Sergey
Published: April 2023

The purpose of the present research is to find approaches for the implementation of constructive solutions that allow for stable suspension and transverse stabilization of magnetolevitation transport systems based on permanent magnets. In order to achieve this goal, the methods of physical modeling were used. Measurements of the magnitude of magnetic induction were carried out using a certified magnetometer Aktakom ATE-8702. While conducting experiments and creating physical models, NdFeB permanent magnets with dimensions of 21x21x21 mm were used. As a result, the suspension and transverse stabilization design based on permanent magnets has been developed and patented. Within the framework of the research, a mock-up of a suspension device for a magnetolevitation transport system was developed and manufactured. The outcomes obtained can be used in the development of technical units with reduced energy consumption, with a minimum coefficient of friction in the guides (escalators, travelators, elevators, etc.), with reduced vibration (magnetic supports) and with minimal consumption of lubricants.
Optimization of the length of dispatching polygon sections railways
Authors: Chebotareva Evgeniia , Chebotnicov Vladimir , Chebotarev Vladimir
Published: April 2023

The article deals with the organization of work of the dispatcher’s office on directions with a high intensity of mixed cargo and passenger traffic. The North Caucasus Railway, which serves the ports of the Azov-Black Sea basin of Russia, and its main busy routes, was chosen as the research site. A methodological approach to determining the length of dispatching sections at the railway landfill within the framework of the Road Traffic Control Center has been developed. At the initial stage of studying the content of the work of train dispatchers, the algorithms developed by the authors are used solving operational management tasks. The analysis of non-optimal actions of the train dispatcher that cause losses in the transportation process is used further to develop a method for estimating losses in operators of problem algorithms based on the interval estimation method by solving a linear programming problem. As a result, based on the assessment of the capabilities of the operational personnel of the railway polygon of the road and the technological cost of delays in movement due to its suboptimal actions, a methodological approach is proposed to determine the length of dispatching sections that provide regulatory control, load level of the dispatcher device.
Errors of sensors for conversion of multi-phase currents into voltage in power supply systems
Authors: Abubakirov A. , Sadikov Zh. , Ramazonov Kh. , Allanazarov B. , Bekimbetov M. , Embergenova N.
Published: April 2023

The paper presents the structure of the sensor for converting multi-phase primary currents into secondary voltages of reactive power of power supply networks, the algorithm for modeling processes in the sensor that sends a signal to the primary current monitoring and control devices provides a highly formalized graph model based on an analytical expression, static characteristics and sensor errors studied on the basis of its analytic expression.
Parameters of the transformer substitution diagram
Authors: Gorskiy Anatoliy , Chernysheva Yulia
Published: April 2023

Determination of the parameters of the transformer circuit is a very important task, as there are a huge number of them (transformers), of different power, different designs, performing different tasks, working in different conditions at voltages and currents of different frequencies and form. This article deals with the determination of the parameters of greatest interest, the parameters that take into account the phenomena in the magnetic core, and the active resistances of the windings, which are calculated for the increased frequency (up to 30 MHz), implemented in secondary power supplies and other semiconductor devices.
Traction SRM simulation taking into account the radial interaction of the rotor and stator
Authors: Tchavychalov Maxim , Yaitskova Natalya
Published: April 2023

The article presents the features of traction switched reluctance motors with a diametric closure of the magnetic flux and a “short field”. A computer simulation of a motor with a short field is performed for the ideal location of the rotor inside the stator, as well as for two cases of rotor displacement. The hodographs of the radial interaction forces of the rotor and stator are calculated.
Comparison of quantized transfers of a given volume of gas through a pipe under its temporal and velocity probability distributions
Authors: Bubnov V. , Sultonov Sh.
Published: April 2023

The paper considers the quantization of gas volume transfers along a hypothetical pipe. The volume of gas is represented by two probability distributions in temporal and velocity form. The known model of optimal in the sense of filling information quantization is applied to quantization of material objects. There is a constant size gap between quanta. Technological aspects of formation of quanta are not considered. On the basis of the carried out minimum cost study the advantage of velocity quantization over time quantization for a number of selected quanta is determined. A normal probability distribution is taken as the initial distribution of the gas volume. The results of the article can be applied to any material and information processes. The main purpose in future research is recommended for any complex network processes, analysis and synthesis of their quality.
Pulling resistance of the front plow cornercutter
Authors: Kurbаnov Sherzod , Temirov Isroil , Khashimova Yorkinoy , Berdimuratov Parakhat , Yuldoshev Said
Published: April 2023

When installed on the frontal plow, the bodies will work in conditions of semi-blocked cutting. The purpose of the study is the theoretical determination of the traction resistance of the frontal plough's cornercutter. The basic principles and methods of classical mechanics, mathematical analysis and statistics were used in this study. Analytical equations for determination of traction resistance of cornercutter beam and plough have been obtained. It is established that traction resistance of frontal plough corners depends on cornersner and plough parameters as well as on physical-mechanical soil properties. At speeds of 1.8-2.3 m/s, traction resistance of the corrugated plough is 0.36-0.39 kN.
The connection between air flow regime and heat transfer in the boundary layer of the brake disc cooling unit
Authors: Polyakov Pavel , Yaitskov Ivan , Tagiev Ruslan , Zadayanchuk Nina
Published: April 2023

The boundary layer of the air flow blowing the surfaces of the brake mechanism prevents heat transfer from heated surfaces. The obtained analytical dependences of the velocities` and temperatures` distribution in the boundary layer represent the field of the boundary layer as a multilayer structural model, the laws of change in the velocities and temperatures of the air flow blowing depend on various sub layers of the boundary layer. According to these analytical dependencies, a thermal model “ventilated brake disc - external condition” was developed. The thicknesses of the boundary layers of the air flow blowing on the various surfaces of the brake disc are determined by various processes. For the working surfaces of the brake disc, the determining criterion is the thickness of the diffusion layer, while for the surfaces of the ventilation apparatus, the criterion for estimating the thickness of the boundary layer is thermal processes. In future, the developed thermal model “ventilated brake disc – external condition” should be the basis for thermal calculations in designing disc-shoe type brake mechanisms.
Synthesis of complex compounds of the monoammonium salt of glycyrrhizic acid and thiourea
Authors: Askarov Ibrahim , Isaev Yusup , Tashtemirova Gulnoza , Rustamov Sanjar , Kadirov Mahamadzarif , Shadmanov Kamoliddin
Published: April 2023

With poor (low) solubility in the aquatic environment, highly toxic drugs (aspirin, doxorubicin, daunorubicin, sulfonamides and others), a low level of glycyrrhizic acid (HA) leads to a decrease in the toxicity of drugs and increases their biological activity due to poor solubility in water. The stability constants (stability) and the value of the Gibbs energy of the synthesized supramolecular complex have been calculated, theoretical and experimental research methods were used to determine the conditions for obtaining supramolecular complexes of glycyrrhizic acid and thiourea. These researches were carried out as part of joint work to study the effect of the toxicity of medicines on a living organism, under an interuniversity program between Andijan State University and the Tashkent Pharmaceutical Institute of the Republic of Uzbekistan. The aim of the research is to determine the stability constant (stability) of the synthesized supramolecular complex of the monoammonium salt of glycyrrhizic acid (MASHA) with thiourea and the value of the Gibbs energy. To determine the structure and composition of the resulting supramolecular complex of MASHA with thiourea, UV and IR spectroscopy and the isomolar series method were used.
Study of a unified work process of internal combustion engines
Authors: Musabekov Zakirjon , Boymurotov Sardor , Normatov Mukhriddin , Askarov Alisher , Shukurulloyev Sarvar
Published: April 2023

Gasoline engines are characterized by high power density and low fuel efficiency. Diesels, on the contrary, have high fuel efficiency, but low specific power. A promising (unified) workflow should combine the best qualities of gasoline engines and diesel engines and work on the entire existing range of fuels produced for them. This will make it possible to switch to a single unified fuel, including fractions of modern commercial fuels, which will significantly reduce the energy intensity and cost of their production.
Synthesis of a graft copolymer of chloroprene rubber with acrylic acid as a shoe adhesive
Authors: Rafikov Adham , Khodjaeva Saodat , Sadikov Rustam , Jalilov Shukhrat
Published: April 2023

Synthesized graft copolymers of chloroprene rubber with acrylic acid. A mixture of benzene and dimethylformamide was used as a solvent, and potassium persulfate was used as a polymerization initiator. Based on the dependence of the copolymerization rate on the concentrations of components and temperature, the order of the reaction rate in terms of the concentration of acrylic acid (2.0), potassium persulfate (1.2) and the activation energy of the process (24.4 kJ/mole) were determined. The degree of grafting of polyacrylic acid increases from 2% to 140% with increasing process time, monomer and initiator concentrations. Grafting efficiency is high (70-90%) in a wide range of time and component concentrations. The graft copolymer has high adhesion to the surface of the skin and tissue.
Determination of the heat-retaining capacity of layered materials for shoe lining by the method of mathematical planning of the experiment
Authors: Mirzayev Nodir , Rafikov Adham , Yuldashev Farrukh , Alimkhonova Sevara , Pulatov Temur
Published: April 2023

A layered composite material for shoes was obtained by the adhesive bonding method. The middle layer of the material consists of a non-woven material made from a mixture of camel and sheep wool, the top and bottom layers consist of cotton jersey, and a polymer adhesive is located between the layers. The layers are bonded by thermal duplication at a temperature of 150±5°C for 2.0±0.2 minutes. As an optimization parameter, the heat-retaining capacity of the material was chosen depending on the thickness, surface density and percentage of camel wool. The strength and thermophysical properties of the layered material are determined.
Computational methods for studying the thermal state of frequency-controlled asynchronous traction motors
Authors: Iksar Elena , Akhmedova Nodira , Yuldasheva Nafisa , Kayumov Sayfulla , Agzamova Mutabar
Published: April 2023

The article discusses methods for calculating the thermal state of a frequency-controlled asynchronous traction motor, and provides calculations of the thermal state of an asynchronous motor powered by a semiconductor frequency converter with an autonomous inverter. Methods for assessing the thermal state of traction asynchronous electric motors of locomotives under various operating modes are considered. Computational methods for assessing the thermal state of asynchronous motor units allow you to continuously monitor the thermal state of an asynchronous traction motor and prevent possible emergencies in a timely manner.
Theoretical analysis of the vibration inducing processes of the “workpiece-mandrel” assemblies during gear-tooth milling
Authors: Kharlamov O.G. , Finochenko T.A. , Chukarin A.N.
Published: April 2023

The theoretical study of the acoustic characteristics of the “workpiece-mandrel” technological system during gear-teeth milling has shown that for calculating the sound pressure levels, it is necessary to determine the vibration velocities of the workpieces and mandrels at their natural vibration frequencies. The paper presents the results of the theoretical studies of the vibration velocities of the processed gear wheels and mandrels during gear-tooth milling by the rolling and copying method.
Advanced drainage of the sides of a coal mine by horizontal wells with a camouflage cavity
Authors: Baymirzaev B. , Murodbekov U. , Mamarajabova Z. , Morozov V.
Published: April 2023

The article presents the results of experiments on models made of equivalent materials of the operability of wells with a camouflage cavity and comparison with the output of groundwater by a natural aquifer. In the experiment, the geometric, physical similarity of materials in the nature of the model was observed. The results obtained showed that when using wells with a camouflage cavity, not only increases the inflow of groundwater, but also decreases the peak loads of depression stresses on the array, as well as the moistening of rocks around the aquifer, in addition, a graph is shown of the rate of water outflow in time on which with the distribution of water inflow without peaks at the time of the formation of washouts. The conducted experiments have shown good performance of wells with camouflage cavities providing effective drainage of the instrument array.
Adaptation and optimization of a photovoltaic system for a country house
Authors: Zikrillayev N. , Ayupov K. , Mamarajabova Z. , Yuldoshev I. , Saitov E. , Sabitova I.
Published: April 2023

This chapter provides the rationale for monitoring photovoltaic (photovoltaic) systems, its purpose, the need for proper measurement, and the frequency required to obtain meaningful results. The need for system monitoring falls into three groups: user feedback, performance review, and system evaluation. Each group is briefly summarized; other related topics include calibration, data storage, and data transfer. The text covers various monitoring modes such as performance testing, system evaluation, data collection and storage, as well as data analysis and reporting. The evaluation standards given by the International Electrotechnical Commission (IEC) are noted in the Data Analysis and Reporting section. The figures are provided to illustrate several types of displays that are an integral part of monitoring. Optimized modes of operation of the power part of a household photovoltaic system consisting of photovoltaic panels, an MRRT controller, an inverter and an electric energy storage unit, with Autonomous and network connection of the load. To build an optimal and cost-effective energy management strategy, it is necessary to take into account the energy profile of the resident, the characteristics of electricity production based on photovoltaic cells, and the electricity tariff for utilities. A photovoltaic system can be connected to the grid in order to receive energy from the grid or enter it into the network to eliminate the discrepancy between the generated, consumed and stored energy.
Equation of motion of the point of the paddy mound in the dryer drum
Authors: Bekkulov B.
Published: April 2023

During the drying process, the more time the paddy pile is in the dryer, the higher the drying efficiency of the device. Thus, the movement of the paddy along the OX axis is one of the main factors affecting the drying efficiency of the device. Paddy movement along the OX axis depends on the speed of the drying agent. Therefore, in experimental studies, it is advisable to determine the optimal value of the speed of the drying agent in the range from 0,25 m/s to 0,75 m/s. The number of revolutions of the dryer drum provides mixing of the paddy mound. The mixing of the paddy during the drying process is one of the factors that leads to an increase in the drying efficiency of the device. Therefore, it is advisable to determine the optimal value of the number of revolutions of the dryer drum from 16 min-1 to 22 min-1.
Development of thermocyclic processing modes for carbon steels used on cold forming tools
Authors: Ergashev D. , Khudayberdiev O.
Published: April 2023

In this paper, the effect of thermocyclic processing regimes on carbon tool steels used in cold stamping tools is considered. Thermocyclic processing (TCP) is based on the idea of repeated heating-cooling of steels at a temperature different from conventional heating. In this case, the values of temperature at high and low levels, the heating-cooling rate can be constant. Unlike traditional methods, in thermocyclic processing, each successive cycle occurs with a new structure and phase change. This makes it possible to significantly increase the properties of steel that cannot be achieved with conventional heat treatment due to the combination of different properties that are formed after the final cycle of thermocycling.
Information measuring system for training assessors to determine the odour threshold using the dynamic olfactometry method
Authors: Meshalkina Marina , Moskvina Irina , Sushnikov Viktor
Published: April 2023

This article presents the results of training, selection and control of a group of assessors to determine the odour threshold. General recommendations of the European standard EN 13725: 2003 “Air quality － Determination of odour concentration by dynamic olfactometry” for the training, selection and supervision of a group of assessors were used in this work. A trained assessor team or panel is the odour measuring instrument. The dynamic olfactometry method was used to determine the concentration of odour in a gas sample. N-butanol was chosen as the odour sample. The experimental setup for the selection and training of a group of assessors to determine the odour threshold is a information measuring system. This information measuring system provides high accuracy and reliability of measurements. The authors chose the Scentroid SM 100 olfactometer and the Agilent 7800 A gas chromatography-mass spectrometer with a 5975C mass-selective detector as a mean of measuring in information system. The referenced value of odour threshold for n-butanol was set to 38 ppb for a panel of 8 selected n-butanol assessors. The number of steps in the dilution series was 6. The instrumental dilution range was 11 ppb to 145 ppb.
Model of the aggregation process of fine ferromagnetic particles
Authors: Birukov Valeriy , Opalev Aleksandr , Nikitin Roman
Published: April 2023

The most important result of the effect of interparticle interactions of ferromagnetic particles in suspensions is the formation of aggregates and modification of their physical properties, which allows changing the kinetics of separation processes. The interest of the authors to this problem is dictated by both its theoretical content and purely applied aspects within mineral processing. Based on the block-structural approach to technological equipment modeling within the framework of the ideal mixing model, a mathematical model of processes occurring in the working volumes of apparatuses using magnetic forces to intensify the separation of mineral suspensions was created. The use of the MATHCAD software has allowed obtaining analytical solutions of the differential equations system of the model and predictions of the kinetics of aggregation of ferromagnetic particles and physical properties of the formed aggregates, such as coarseness, density, deposition velocity in the gravity field as functions of medium parameters and external magnetic fields. The analytical solutions are necessary for developing simulation models of magnetic separation processes in strong, weak, uniform and non-uniform magnetic fields, magnetic deslammers and filters.
Improvement of the well cementing technology
Authors: Hadid Mahmoud , Minchenko Yulia , Shemelina Olga , Ovchinnikov Vasily , Pavelyeva Yulia
Published: April 2023

The article presents measures to improve the quality of cementing the production string of high-performance wells. The relevance of the proposed technological solutions is substantiated. The results of experimental studies of the installation simulating the processes occurring during the thickening of the cement slurry under the action of gravitational forces are presented. An algorithm for creating overpressure on the wellhead during fastening of the production string is proposed. The compositions of process fluids are described, which increase the reliability of the annular space isolation and preserve the permeability of the reservoir, and provide the main data on the results of their laboratory studies. For cementing the annular space of the production string, the composition of the expanding cement slurry has been developed and the procedure for its preparation has been established. The proposed solution has low water separation and high sedimentation resistance; has adjustable rheological parameters. Cement stone is characterized by low gas permeability and high strength properties.
Valuation of the influence of the basic specific resistance to the movement of freight cars on the energy costs of driving a train
Authors: Masharipov Masud , Rasulov Marufdjan , Suyunbayev Shinpolat , Adilova Nazdana , Ablyalimov Oleg , Lesov Altinbek
Published: April 2023

The primary specific resistance to the movement of freight wagons is a key parameter for normalizing the time and energy consumption of trains. Although the “Rules of Traction Calculations” calls for dividing wagons into six groups when calculating this resistance, in practice (using the traditional method), appropriate regulations are developed based on the separation of train wagons into two groups (4th and 8th lips). One of the main reasons for this is the inability to account for the unique features of each wagon in a given train. To address this issue, a program was developed for determining the necessary parameters of wagons for traction calculations based on their identification numbers. This software can be accessed through the website https://trainlocomotive.netlife.app/. Using this program, a method for calculating the primary specific resistance to the movement of freight wagons has been developed. Field sheets of freight trains moving through the Uzbekistan Temir Yullari railway station were analyzed. As a result, it was discovered that nearly half of the freight train composition consists of empty wagons, while the proportion of loaded gondola cars and tanks is 23%. The primary specific resistance to the movement of wagons in such a mixed composition is calculated using both traditional and developed methods. The impact of the primary specific resistance on the energy costs of maintaining the train is evaluated. As a result, the feasibility of utilizing the developed method for normalizing electricity consumption based on traction calculations is demonstrated.