METHODOLOGICAL FOUNDATIONS FOR SUBSTANTIATING SAFE LEVELS OF EXPOSURE TO ARTIFICIAL NANOMATERIALS (FOR EXAMPLE, CARBON NANOTUBES)

The unique physicochemical properties of carbon nanotubes allow them to be used in many fields. The global nanomaterials market is growing every year. An important step in introducing products to the domestic and world markets is to determine the safe exposure levels of CNTs. Establishing a corporate standard can serve as a preliminary stage before the approval of a state hygiene standard. Justification of the corporate standard is carried out in in vitro and in vivo experiments. The planning of experiments should be carried out taking into account the target organ under the influence of CNT - the respiratory system. The recommended dose / concentration range for experiments should include doses / concentrations derived from calculated and literature data. A necessary step is to obtain homogeneous dispersions in which CNTs become bioavailable for biological systems. During in vitro and in vivo experiments, the exposure level is determined at which no harmful effect is observed and / or the lowest level of exposure at which there is a harmful effect on the cell culture / respiratory tract of animals.

Mini crusher-shredder for farms

The purpose of the study is to substantiate the parameters of a mini crusher-shredder for processing coarse feed stalks in farms. The feasibility of using a mini crusher-shredder for processing coarse feed in the conditions of farms and farms with a small number of animals, which has a rotary-type shredder that combines the operations of grinding and crushing, is justified. The research uses the laws and rules of mathematical statistics, mathematical planning of experiments, and the methods given in existing regulatory documents. Experimental studies were carried out to study the influence of the rotor parameters of the mini crusher-shredder on its quality performance. A compact crusher-shredder has been developed, which has good visibility of the working bodies, high reliability, and quality of work due to zootechnical requirements. Experimental studies have established that when using a hammer of a flat-turned shape with a lower sharpening and a rotation angle of 60 or more, high-quality grinding of the stems is provided.

Parameters of the angle-lift of the front plow for smooth, rowless plowing

To improve the quality and energy indicators on the front plow in front of the housings, the angle axes are installed in the form of a triangular wedge. The purpose of the study is to substantiate the parameters of the angle-lift of the front plow, which provides high-quality performance of the technological process according to agrotechnical requirements with the lowest energy costs for smooth, rowless plowing. The research uses the laws and rules of theoretical mechanics, mathematical statistics, mathematical planning of experiments, and methods of strain measurement, as well as the methods given in existing regulatory documents. Based on the study of the process of interaction of the carbon monoxide with the soil, analytical dependences are obtained that allow us to determine the parameters of the carbon monoxide. According to the results of theoretical and experimental studies, it was found that the required quality of tillage with a front plow following the established agrotechnical requirements with minimal energy consumption is provided at the height of 22 cm, a length of 27 cm, a wing angle of 32° and an angle of inclination of the side face of 36°.

Improving the installation of fire gasing with gelelating compounds

It is established that the organization of fire extinguishing with the use of gel-forming compounds is a promising direction to increase the efficiency of extinguishing, especially in multi-storey buildings and structures of various functional purposes. Given the shortcomings of existing technical solutions for the use of gel-forming compounds for effective fire extinguishing, the need to develop new structures (spray barrels) is justified. The proposed solutions should ensure, above all, the safety of the fire rescuer. New designs of spray barrels must have a distance of supply of gelling compounds to make work of the operator safe, as well as meet the general technical requirements for fire extinguishers. An autonomous installation of extinguishing with gelling compounds for remote fire extinguishing by plane-radial jets of components of gelling compounds has been developed. It is proposed to fix the spray barrels with a special device to guide them to the object that has to be extinguished with verification of the angles to the horizon, angles of deviation relative to the plane of aiming, the height and width of the symmetrical placement. In this manner, it allows more efficient feeding at a distance of up to 10 meters of the two components of the gelling compounds and prevents premature or delayed mixing. Full-scale samples of RS-10 spray barrels were designed and manufactured to supply flat-radial jets of gel-forming compounds at a distance of up to 10 m. The method of optimal planning of experiments was used to calculate rational values of geometric parameters of the initial cross-section of the RS-10 spray barrel. The problem of 4-factor (second-order) optimal planning of the experiment of the process of plane-radial jet supply by means of RS-10 spray barrels is formulated and carried out. The main design parameters of the spray barrel (cutout of the rigid plate sector and its thickness) are determined, which correspond to the area of rational geometric parameters. The obtained results can be used in the design of extinguishing systems with gelling compounds

Technological process of uniform distribution of fertilizers over the width of the coulter

The applied methods of applying fertilizers for cotton in Uzbekistan do not fully ensure the supply of nutrients to the plant's root system. The study aims to substantiate the technological process of uniform distribution of fertilizers in the root development zone and the parameters of coulters. When the fertilizer is distributed in the root development zone in tiers and the right ratio, the coefficient of their use increases, and the yield of cotton increases. The research uses the laws and rules of theoretical mechanics, mathematical statistics, mathematical planning of experiments, and the methods given in existing regulatory documents. The technology of forming new ridges instead of existing ridges and new furrows instead of existing furrows in fields with harvested husk with simultaneous fertilization and an improved chisel cultivator-fertilizer with comb-forming agents for its implementation, as well as the results of theoretical studies to substantiate the main parameters of the tuk coulter chisel-cultivator are presented. The study determined the parameters of universal fertilizer Coulter chisel-cultivator of fertilizer: the base cone of the diffuser in the form of an ellipse with minor axis width 10 mm, height tool provider relative to the upper base of the truncated cone of 60 mm, and a diameter of a half-cylinder of 20 mm.

A Study of the Potential Use of Red Mud to Obtain Compositions Based on Portland Cement

The paper deals with the problem of utilization of red mud which is a waste product from alumina production using the Bayer method. The principal possible use for the red mud of JSC “Bogoslovsky aluminum plant” (Sverdlovsk region) for the compositions based on Portland cement is shown. It was found that the mud introduction accelerates beginning of the cement paste setting and thickens the paste reducing its mobility. It is concluded that the introduction of red mud up to 30 % is justified in terms of strength indicators. The work is carried out using mathematical planning of experiments. Keywords: red mud, Portland cement, active mineral additive, composition, properties, bauxite, chemical composition, cement stone strength, mathematical planning of experiments

Mathematical Modeling of Fire-Proof Efficiency of Coatings Based on Silicate Composition

The paper analyzes the scientific work on fire protection, fire resistance, mathematical modeling of fire-proof properties, mathematical planning of experiments. The factors determining the efficiency of fire-proof coating have been determined. The experimental technique for determining fire-proof efficiency as an output parameter was selected. A factor space was constructed, and an experimental plan was drawn up. Experimental studies of the fire-proof effect of the coating based on the xerogel of the gel-forming system at all points of the factor space were carried out. A regression equation was obtained that describes the effect of the qualitative and quantitative composition of the coating on its fire-proof efficiency.

APPLICATION OF THE DEVICE FOR RECEIVING AND TRANSFER OF SEEDS IN THE TECHNOLOGY FOR PREPARATION OF LOWERED SEEDS AND SUBSTANTIATION OF THE BASIC PARAMETERS

The article analyzes the development of technology for the preparation of pubescent sowing seeds, based on the effectiveness of the development of a device for receiving and transferring pubescent seeds and its application in technology. The results of determining the optimal sizeof the device for receiving and transmitting pubescent seeds by the method of mathematical planning of experiments are presented.As a result of determining the optimal size of the pubescent seed receiving and transmitting device (UPS) by the method of mathematical planning of experiments, the pitch of the screw conveyor is 165 mm, the rotation speed of the screw conveyor is 20 rpm, the guide-adjuster and the distance between the screws were 50 mm

Modeling of compositions and predicting properties of modified mixtures for rough thin-layer coatings

In recent years, the approach to experimental and statistical research and optimization of complex multicomponent systems has changed radically. In various fields of scientific and technical research, methods of mathematical planning of experiments are successfully used. Their wide application significantly increases the effectiveness of research, as well as proves their universality and suitability in most studies of building materials. As a result, the authors present a method of mathematical planning of the experiment, which is used to optimize the composition and properties of modified mixtures for rough thin-layer coatings. This method allows a fairly complete and comprehensive assessment of the effect of components on the properties of modified mixtures and to obtain a mathematical model of the process in graphical form, as well as to obtain a theoretical model for evaluating and predicting the physical, mechanical and operational properties of the materials under study. In this article, the first stage of research was used to select the percentage of binder, hydrate lime and additives, and also studied the influence of the variation factor of these components on the physical and mechanical properties of the mixture. At the second stage, changes in response functions were investigated. The results of a complete three-factor experiment allowed us to establish rational ranges of values of the studied components in order to obtain mixtures for rough concolay coatings with optimal values of physical, mechanical and operational parameters.

Rationalization of the constructive form of towers with prestressed cables

Relevance. One of the main directions of development of mobile communication systems, radio engineering and telecommunication systems is the improvement of the structural form of the bearing supports, which will solve a number of practical tasks: to increase the coverage area, to ensure higher rates of data transmission speed and to ensure stable operation in an increasing number of users. These circumstances justify the relevance of research in this direction. Aims of research. Optimization of design solutions using parallel puffs, ensuring the possibility of erection and safe operation during the entire service life, which ensures that the requirements for strength, stability and deformations for such structures are met with minimal material consumption. Methods. For calculations, finite element methods are used for mathematical modeling using software and computing systems. To create linear models for numerical experiments, the method of mathematical planning of experiments was used. Results. The work of the towers of the proposed constructive solution is considered as supports for the placement of equipment of cellular operators using the example of a 42-meter tower. The method of mathematical planning of experiments was used to create a model line for numerical experiments. To establish the basic characteristics of the stress-strain state of the structures of the supports, a number of models were created and calculated in software packages, the basis of which is the finite element method. A comparative analysis of the effort in the delays determined by analytical calculation and the finite element method is performed. The analysis of changes in the stress-strain state of the towers from the influence of influencing factors, such as wind and icy-wind loads, the angle of deflection on the lower tier of the tower. By the criterion of minimum metal consumption and manufacturability of the construction of towers, rational overall dimensions of the tower were determined. The options for constructing the main junctions of the elements of the tower are proposed.