Search

Superluminescent diodes based on AlGaInAs/InP separate-confinement double heterostructures with strain-compensated quantum wells are investigated. The influence of elastic strains in the active region on the output characteristics of the devices is analysed. It is shown that such a design of a superluminescent diode allows an optical power of more than 5 mW, a radiation spectrum width of more than 60 nm, a degree of output radiation polarisation up to 30 dB to be obtained at the output of a single-mode fibre, and has a great potential for further improvement.

This paper presents a study of the properties of erbium-doped optical fibres with enhanced gamma-ray resistance at a high dose rate. The fibres have a silica core containing different dopants. The gamma-ray resistance of the fibres is due to additional doping of their core with cerium and germanium ions, as well as to aluminium concentration optimisation. We assess the effect of fibre composition on the radiation-induced loss at a wavelength of 1310 nm and the output power and weighted average wavelength of superluminescent fibre sources based on erbium-doped fibre under pulsed gamma irradiation (dose per pulse, ∼ 20 Gy). The fibre doped with aluminium, germanium and cerium oxides is shown to be optimal for use in gamma-ray-resistant broadband superluminescent fibre sources.

The paper presents to topical issues of functional food production technology, which has its own characteristics. Since milk and dairy products are initially a source of bioactive substances in the form of vitamin B2 (riboflavin) and Ca, from a technological point of view, it is advisable to add functional components rich in dietary fiber and antioxidants to the formulation. At the same time, special attention should be paid to the issues of preserving the beneficial properties of bioactive substances not only in the process of preparing raw materials for introduction into a product, but also at subsequent stages of the production-consumption cycle. Food products made from milk and its derivatives have functional properties aimed at normalizing the functioning of the gastrointestinal tract, increasing the body's immune resistance to pathogens of infectious diseases and leveling the harmful effects of the environment. Herbal preparations from essential oil plants of the Lamiaceae family are distinguished by a high content of dietary fiber, have high antioxidant activity and have an immune-strengthening effect on the human body. The average annual increase in the output of curd products in the dairy industry is about 8-13%, which indicates the prospects for the development of new recipes for functional curd-based products.

The problem of constructing fundamental solutions to the thermoelasticity problem for a piecewise-homogeneous transversely isotropic space is reduced to the matrix Riemann problem in the space of generalized slow growth functions. As a result of the solution of which, were obtained expressions in explicit form for the components of the stress tensor and the displacement vector in plane of connection of transversely isotropic elastic half-spaces containing concentrated stationary heat sources. The temperature distribution is investigated depending on the thermophysical characteristics of the half-space materials.

The purpose of the article was to study the quality as a basis for the export potential of Ukrainian meat products and to determine the conditions for its improvement. The following methods were used: abstract-logical; monographic; comparative analysis; statistical; tabular. The results of the research show that the problem of quality assurance of both agricultural products in general and poultry meat in particular is most relevant in both domestic and foreign markets. It covers all participants in the food chain “production-processing-sale-consumption”. Product quality is the main factor in the stable development of production and ensures the export of domestic products. It is established that the production of poultry meat in Ukraine fully meets domestic demand and has reserves for export. It is substantiated that the recognition and provision of competitive advantages in the international and domestic markets can be achieved only by those enterprises that implement international standards of product quality and safety, constantly upgrade technological equipment, introduce new technologies and have highly qualified personnel, create their own feed and raw materials processing.

A method of numerical modeling based on splitting by physical processes of two-phase fluid transfer in a formation with fractured-porous reservoirs is described. Reservoirs of this type have a natural fracture system and are described by the dual porosity model. A four-block mathematical model of the fluid redistribution between a pore-type matrix and a natural fracturing pattern is proposed and studied. The resulting system is complex and entails a number of difficulties associated with a large number of variables and the absence of important properties of a linearized system of equations, such as self-adjointness and symmetry, which are present in the description of piezoconductive processes. The complete splitting by physical processes is carried out to solve this problem. The resulting split model is differentially equivalent to the discrete initial balance equations of the system (conservation of the mass components of the fluids and the total energy of the system), written in divergent form. This approach is associated with a nonlinear approximation of the grid functions in time, which depends on the fraction of the volume occupied by the fluids in the pores, and is easy to implement.

The geodynamic consequences of the field development process include the subsidence of the earth’s surface. Monitoring of deformations in offshore fields is difficult and it is necessary to evaluate them by various methods. It is important to investigate how much the calculated amplitude of the seabed subsidence is reduced by taking into account changes in the porosity and compressibility of the pore space with a decrease in reservoir pressure. The analysis of changes in the petrophysical parameters of the reservoirs of the Daginsky horizon during the projected development of the Yuzhno-Kirinskoye hydrocarbon field for depletion and a decrease in formation pressure by 10 MPa showed that the porosity decrease will be 0.038 absolute percent, the compressibility of the pore space will decrease by 0,08 10-3 1/MPa. With the help of the Petrel software, changes in the thickness of the productive layer from 80 to 120 cm were obtained, which can be taken as an estimate of the seabed subsidence in the area of the field. The application of the genetic model of the deformable formation by Kuzmin Yu showed that the maximum amplitude of the seabed subsidence to be 101 cm. Comparison of these estimates of the seabed subsidence indicates their proximity. Taking into account the dynamics of tectonophysical and petrophysical characteristics due to the long-term development of hydrocarbon deposits significantly changes the intensity of the deformation state of the rock mass and the earth’s surface above the field.

The paper presents an algorithm for solving the problem of the process of mass transfer of a two-phase fluid in a fractured-porous reservoir in a one-dimensional formulation. The presence of natural fractures in such reservoirs impedes various types of exploration and field development. Fractured-porous reservoirs are characterized by intense exchange fluid flow between fractures and porous blocks. Each system has its own individual set of filtration-capacity parameters, and this fact complicates the problem under consideration. To study the mass transfer of a two-phase fluid in a medium with double porosity, a four-block mathematical model with splitting by physical processes is proposed. The model is described by a system of partial differential equations. The splitting method forms two functional blocks on the water saturation and the piezoconductivity. For the numerical solution of this system, an absolutely stable implicit finite-difference scheme is constructed in the one-dimensional case. On the basis of the proposed difference scheme, pressures and saturations in the fracture system and matrix are obtained.

The article presents the results of experimental studies of technological effectiveness of formation of planting furrow by working body of passive type of orchard planting machine. The authors adhered to working hypothesis that to reduce energy consumption and increase the reliability of orchard planting machine in various operating conditions, possibly due to passive type of working body, which provides undercutting the soil layer and raises it to formation of planting furrow, and after placing the seedling in it, it encloses it as before area without additional significant movement or rotation. The article presents the results of study of number of roots hooks of two-year-old apple seedlings when trying to place their root system in interval between the opener model extensions. The authors presented the models of schemes of interaction between plant stems and blade of main blade and optimized the parameters of working surface of barrel blade. The authors established the dependence of additional averaged soil resistance coefficient on planting depth. The article investigates the dependence of resistance force of working body of orchard planting machine on planting depth and soil type. The authors presented the results of technological effectiveness of prototype of working body of orchard planting machine during experimental research and production tests.

The impact of concentrated NaCl, NaNO3, and Na2SO4 solutions on the average hydrodynamic diameter and charge of particles of slightly soluble nickel and copper compounds were found to be rather identical. In electrolytes solutions, the average size of the dispersed phases particles decreased from 50–54 µm to 30–45 µm, the electrokinetic potential became more negative (-(2–10) mV). In a result, the removal of slightly soluble nickel and copper compounds decreased from 98% to 94–97% and 30–94%, respectively. Minimal efficiency of electroflotation-based extraction of nickel was observed in the presence of NaNO3. Cationic flocculants promoted increased extraction up to 98–100% regardless of the electrolyte, and decreased electroflotation duration from10–15 min to 5–7 min.

Cerium-substituted hydroxyapatites (Ce-HAs) with an estimated content of Ce3+ of 0; 0.1; 0.25; 0.5 mol. % were prepared by two different synthesis methods: precipitation from aqueous solutions of salts and mechanochemical synthesis. The powders after synthesis were heat-treated at 1250 °C to achieve well-crystallized phases. The X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), energy dispersive analysis (EDA), and dilatometry methods revealed that cerium ions didn’t not fully incorporate into the HA structure, but rather were transform to the CeO2 phase. It was attributed to the transition of Ce valency (III)→(IV) through the oxidation reaction under air conditions during materials heating. Two different synthesis methods provided similar phase composition of the obtained compounds, though different microstructure of the resulted ceramics. It was shown that cerium introduction prevents HA sintering during thermal activation, possibly due to contribution of large atomic mass of cerium ions and formation of cerium (IV) oxide at the crystal boundaries.

This work is devoted to studying the effect of the synthesis temperature on the phase composition of Al2O3. Aluminum hydroxide was obtained by a reverse heterophase deposition method. This method makes it possible to obtain the purest hydroxide powder. For the synthesis, several different temperature regimes were selected in the temperature range from 250°C to 1100°C.

The paper presents the results of studies of the impact of operating time of single-bucket excavators on their operational performance. The results of production experiments made it possible to establish the dependence of the pressure change in the hydraulic system of the excavator during the process of cutting soil on the operating time. This parameter characterizes the variation value of the cutting resistance of soil at the cutting edge of a bucket, the duration of operation cycle and its operational productive capacity. Based on the results of the study, a technique has been developed that permits to determine economically feasible periods of effective operation of excavators, as well as to establish the optimal technological parameters for cutting soil: the thickness of the soil shavings and speed of its cutting by an excavator.

Risks of organoleptic (taste and odor) effects in drinking water from three water intake facilities are assessed, and research results are presented. The highest risk values for water hardness were identified in samples from infiltration water intake; the value for color-related risks was constant and equal to 0.001. For surface water intake samples, the values of water hardness and associated organoleptic risk are the lowest, compared to other water intakes, and do not exceed 0.008. Risk values of organoleptic effects associated with color at the surface water intake facilities are within the range of 0.001-0.003. The risk values for the taste, and odor effects due to turbidity are constant for all water intakes and equal to 0.002. There is no risk of developing organoleptic-olfactory products associated with the chemical oxygen demand parameter in all samples. The research shows that the overall values of the organoleptic risks are the highest in instances form infiltration water intakes compared with the surface water intake. In addition, the water hardness parameter contributes the most to overall organoleptic risks for all water intakes. The authors conclude that the risks associated with organoleptic (taste and odor) effects do not exceed an acceptable level, both for each indicator considered separately and for their combined effect.

Safety of food products is assessed by hygiene standards, which include biological, chemical and physical risk factors. Biological risk factors include viruses, bacteria, mold and yeast fungi, protozoa, helminths and their toxins. Their presence in food products is either completely unacceptable, or should not exceed the acceptable ranges of concentrations in a certain volume of the test products. The original scoring technique was used for a quantitative assessment of biological risks. The persistence of microorganisms and helminthes was evaluated in meat, dairy and vegetable products, culinary products, eggs, canned food, pickles and marinades. Among the studied biological risk factors, the following have very low persistence in food products: adolescari of Fasciola spp.; eggs of Trichocephalus trichiuris, Enterobius vermicularis, Hymenolepis nana, Echinococcus spp., Ascaris lumbricoides, Strongyloides stercoralis larvae, cysts of Lamblia intestinalis, Entamoeba histolytica. Low persistence was demonstrated by Rotavirus, hepatitis A virus, the genus Norovirus, bacteria of the Leptospira spp. and Vibrio spp., Escherichia coli, Toxoplasma gondii and Cryptosporidium parvum. Medium persistence was demonstrated by plerocercoids of Diphyllobothrium spp, cysticercuses of Taeniarhynchus saginatus and Taenia solium, bacteria Shigella spp. and Francisella tularensis. High persistence was shown by larvae of the genus Trichinella, metacercaria Opisthorchidae, bacteria Mycobacterium spp., Proteus spp., Campylobacter spp., Yersinia spp., Brucella spp., Bacillus cereus, Clostridium perfringens, Staphylococcus aureus and Clostridium botulinum. Aphthovirus, Salmonella spp. and Listeria monocytogenes have very high persistence.