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Different types of models are used to study the stress-strain behavior of asphalt concrete mixture during compaction. For modeling it is necessary to know the values of model parameters in the whole range of changes in the characteristics of the compacted material. The aim of the paper is to develop a methodology for determining model parameters based on the results of laboratory creep-recovery testing of asphalt-concrete mixture. In the paper, a model reflecting elastic, visco-elastic and visco-fluid properties of the compacted material is adopted. A differential equation representing the law of behavior of the asphalt-concrete mixture layer under load is obtained. The stages of creep-recovery testing are analytically described, namely: rapid loading with a constant load and deformation under this load; load removal and recovery. Initial conditions for the mentioned stages are determined. Taking into account the initial conditions, analytical expressions of the laws of deformation of the model under the action of a constant load and in the process of recovery are obtained. The methodology of laboratory experiments on creep-recovery is described, according to the results of which the required values of the model parameters with minimum absolute error are obtained. The developed methodology allows to determine the parameters of the model describing the stress-strain behavior of asphalt-concrete mixture of different density and temperature. Consequently, it is possible to simulate the behavior of the asphalt concrete mixture layer at the preliminary, main and final stages of compaction in order to determine the effective operating modes of compaction equipment.

Objectives. Development of a domestic technology for producing environmentally friendly non-phthalate plasticizers, lubricants and transformer fluids based on neopentyl glycol (NPG), an oxo-synthesis product.Methods. The methodology of the work was to study the kinetic laws of NPG esterification with acetic and 2-ethylhexanoic acids under self-catalysis conditions with an 8-fold molar excess of monocarboxylic acids. The production of NPG esters was carried out by azeotropic esterification in the presence of solvents—benzene and m-xylene. The resulting diesters were isolated from the reaction mass by vacuum rectification. The purity of the obtained NPG diesters was no less than 99.7 wt %. Analysis of the qualitative and quantitative composition of reaction samples was carried out using infrared spectroscopy, gas chromatography–mass spectrometry and gas–liquid chromatography.Results. The paper presents the results of kinetic studies on NPG esterification of with acetic and 2-ethylhexanoic acids. It compares the reaction rates and reactivity of the acids used. Under the given conditions, NPG diesters were produced, and some of their physicochemical properties were determined. This enabled the data obtained to be used for the development of industrial technology in the production of NPG diesters.Conclusions. It was established that with an eightfold molar excess of acid under self-catalysis conditions, a yield of NPG diacetate equal to 95% is achieved within 20–22 h at an optimal process temperature of 100–110℃; NPG di(2-ethylhexanoate)—within 26–28 h at 160–170℃. The activation energies and pre-exponential factors for the formation of NPG mono- and diesters with acetic and 2-ethylhexanoic acids were established. The paper presents the kinetic models of esterification.

Objectives. To develop and validate a methodology for determining inorganic iodine in Laminariae thalli L., corresponding to the norms of the State Pharmacopoeia of the Russian Federation, 15th edition (SPh 15). The methodology needs to be valid and suitable for the quality control of pharmaceutical raw materials in factory laboratories.Methods. Cathode inversion voltammetry was used as an instrumental method for determining inorganic iodine using a graphite electrode capable of sorbing electroactive ion associates of surfactant–iodine.Results. When compared with the titrimetric technique recommended by SPh 15, the proposed technique is more selective, sensitive and less time-consuming. The efficiency and metrological characteristics of the technique were confirmed by validation in accordance with the requirements of SPh 15.Conclusion. The paper presents a new method for determining the gross content of inorganic iodine in Laminariae thalli L. This technique can be used not only in scientific research, but also in the routine quality control of medicinal plant raw materials in control and analytical laboratories engaged in pharmaceutical quality control.

Research of changes hydro-puller device internal cavitie’s geometry for order to improve the thermal state The paper is devoted to the study of the influence on changes in their thermal balance during operation by improving the cooling conditions of sections of the drill shaft with contact surfaces of changes in geometric characteristics, such as diameter and length, of the internal cavity for supplying working fluid in high-pressure hydro-puller device for hydro-jet technologies. The axisymmetric simulation not on a full-size transmit-ting device was carried out, but on one-eighth part in order to reduce the time of both creating the model itself and the amount of calculations. A model created in the computing environment «Ansys» with a computational grid for calculating equivalent stresses is shown. The stress distributions calculated by the finite element method for various combinations of the geometry of the transfer device revealed the corresponding boundaries for the rational change in the diameter and length of the internal cavity, allowing to ensure its operability of the structural unit in combination with maximum cooling of the most thermally loaded sections of the shaft. Dimensionless geometric parameters (reduced diameter and reduced length of the internal cavity) are introduced for a general description of the geometry of transmitting devices for hydro-jet technologies. Graphs of the dependences of voltage values on the given values were obtained.

The design calculation of crane metal structures is usually performed according to load combinations, for which the dynamic coefficients are strictly defined in the regulatory documentation. In fact, these coefficients depend on the departure and the length of the suspension of the load, they are different when lifting loads of different weights. A review of the literature has revealed a clear gap in the studies of the dynamics of gantry cranes, which are characterized by a change in the characteristics of their design even during one cycle of their operation. In this paper, to study the influence of the parameters of the gantry crane system on the magnitude of the dynamism coefficients, a dynamic model consisting of the mass of the crane’s metal structure brought to the point of suspension of the load and the weight of the load is applied. The weight of the rope, the elasticity of the lifting mechanism, and the damping of vibrations are not taken into account, and the characteristic of the drive is considered absolutely rigid. A method for determining the parameters of a dynamic model such as structural rigidity, its reduced masses is presented, and the results of calculating the dynamism coefficients for the metal structure of a crane and a rope suspension under various parameters and operating modes are presented. Calculations for a gantry crane with a lifting capacity of 10 tons have shown that with small departures, the dynamic load coefficient in the rope is always less than for a metal structure, while its value is maximum. For large departures, the values of the dynamics coefficients are close to those accepted for calculations according to regulatory documents. These circumstances should be taken into account both in the static calculation of portal cranes and in the calculation of their elements for durability, which will increase their reliability in determining the loading of metal structures.

Hydrogen energetics is undoubtedly highly relevant today as it not only allows solving the issue of energy production from a renewable water source but can also prevent the formation of greenhouse gases. They say that any new idea is a well forgotten old one. The paper is dedicated to an excellent but still unimplemented work of Sainte-Claire Deville who managed to obtain hydrogen from water vapor using membrane technology. He used a clay pipe as a membrane which selectively permeated hydrogen. This process occurred with heating up to 950 °C. Sainte-Claire Deville managed to obtain only a mixture of hydrogen and oxygen in a ratio of 4:1 and then to clean the product from oxygen using chemical reactions. Modern membrane catalysts based on palladium or its alloys are selectively permeable only for hydrogen. This means that the membrane catalysis method with palladium membranes could allow to realize of hermal water disassociation more effectively and solve the issues of hydrogen energetics using only renewable raw materials. The history of hydrogen discovery and methods of its production was also studied in this review. Different methods of energy production were analyzed, including mineral resources, wind turbines, solar panels, hydroenergetics, electrolysis, and nuclear power, and a forecast was presented based on them. The review should be considered as an invitation to further discussions regarding this highly relevant and important topic

Although widely used in the textile industry, methyl orange is considered one of the most toxic dyes, which have negative impacts on the aquatic environment and needs to be removed from water bodies. Hence, the present paper reports the synthesis of new floating photo-Fenton catalysts based on the immobilization of Fe2O3 nanoparticles on the surface of Luffa sponges for the oxalate-induced-degradation of methyl orange. The floating catalytic sponges were prepared through a simple precipitation method followed by a reflux heating process and then characterized by field emission scanning electron microscopy, X-ray diffraction, atomic absorption spectrometry, and nitrogen adsorption-desorption experiments. According to the experimental results, methyl orange was effectively degraded over our floating catalytic sponges under light illumination at near neutral pH. The catalytic activity was also found to be enhanced with the increase in crystallinity of Fe2O3 nanoparticles, which can be achieved by the reflux heating. Besides, owing to the floating feature, these sponges are easily separated from the solution, thereby not forming a secondary source of pollution for water

Spontaneous photomagnetoelectric effect in ferromagnetic GaMnAs epitaxial layers has been investigated. The goal of this work is to study the temperature dependence of the spontaneous PME effect, determined along [110] and [110] crystal axes. GaMnAs layers with Mn concentration of 2.9 atomic percent studied in this paper were grown by low-temperature molecular beam epitaxy on semi-insulating GaAs (001) substrate. It was shown that below Curie temperature in the illuminated GaMnAs epilayers a transverse voltage (photo-EMF) was observed. This photo-EMF is associated with the photomagnetoelectric effect resulting from the separation the photogenerated carriers by the intrinsic magnetic field of the semiconductor matrix in ferromagnetic state. The temperature dependence of intrinsic photomagnetoelectric effect in GaMnAs epilayer was determined along [110] and [110] crystallographic axes. It was found that the photo-EMF measured along [110] crystal axis exhibits a maximum at temperatures of 35–40 K, while the photo-EMF measured along [110] axis increases monotonically with temperature decay. It was shown that the non-monotonous temperature dependence of the photomagnetoelectric effect along [110] axis can arise due to the reorientation of the easy axis of the sample with decreasing temperature

The paper proposes a new approach to the analysis of electrochemical impedance spectra of porous tantalum bodies, which involves modeling the frequency response via an equivalent circuit that takes into account the pore hierarchy. It was shown that the proposed circuit describes well the experimental data and allows characterization of the porous structure, including the contribution of different types of pores to the total capacitance of the porous body, characteristic relaxation times, and activation frequencies for different type pores. Two types of samples were analyzed: a porous tantalum body obtained by sintering Ta powder and a porous tantalum body covered with a Ta2O5 dielectric layer. Modeling showed a significant redistribution of contributions from pores of different types into the total capacitance after the formation of Ta2O5 due to the preferential isolation of the smallest pores and/or those difficult to access. The results of modeling of the frequency response of the analyzed samples agree well with the scanning electron microscopy data. The proposed approach has the potential to be advantageous for the technology of tantalum capacitors