Influence of intrauterine hemodynamics on the C segment of the aortic arch in the fetus

Objective. To assess the correlation between the hemodynamic characteristics of the left ventricle and geometric features of the aortic arch in the fetus.Methods. The study involved 31 fetuses from 29 to 34 weeks of gestation by echocardiography. The scientists assessed the morphogeometric characteristics of the left ventricle andaortic arch. They studied the following parameters: end-diastolic volume ofthe left ventricle (LVEDV), stroke volume of the leftventricle (LVSV), velocity-time integral of the flow through aortic valve (VTI AV), diameter of the aortic valve ring (AV), diameterof the aortic arch segment between brachiocephalic trunk and left carotid artery (dС). Results. The average gestational age was 31,9±1,4weeks (95% CI: 31,4–32,4 weeks). Average body weight 1899±377 g (95% CI: 1762–2038 g). LVEDV = 1,57±0,64 ml (95% CI: 1,3–1,8). LVSV = 1,3±0,45 ml (95% CI: 1,1–1,4 ml). AV 0,4±0,07 cm (95% CI: 0,39–0,44 cm). C segment of the aorticarc is 0,37±0,07 cm (95% CI: 0,035–0,040 cm). There was direct correlation between the variables used to calculate dC (Pearson correlation coefficient: LVEDV = 0,51; p=0,002; LVSV = 0,46; p=0,005; AV = 0,52, p=0,001). The diameter of the C segment of the aortic arch can be calculated using the following equations: dС= 0,76· LVSV +2,8 (95% CI LVSV 0,2–1,3 95% CI for constant2,1–3,6; Fisher’s criterion 7,6 р=0,01). dС= 0,59· LVEDV +2,8 (95% CI LVEDV 0,2–0,98; 95% CI for constant 2,2–3,5; Fisher’s criterion 10 р=0,004). dС= 0,59·AV+1,3 (95% CI AV 0,22–0,95; 95% CI for constant – 0,23–2,9; Fisher’s criterion 10,7;р=0,003).Conclusion. 1)hemodynamic characteristics of the left ventricle allow predicting the sizeof the aortic arch in fetuses from 29 to 34 weeks of gestation; 2)morphogeometric characteristics of the aortic arch are determined by the characteristics of the left ventricular stroke volume, end-diastolicvolume of the leftventricleand the sizeof the fibrous ring of the aortic valve.

Research of the Mechanical Properties of the Filament from the Percentage of Filling when Prototyping Machine Parts

The article contains the analysis of thermoplastics used in prototyping machine parts. We used several types of experimental samples with different filling percentages. The equipment on which the experimental studies were carried out is shown. During the experiment, a specialized tensile testing machine was used. The experimental samples were installed in the developed centering device. Normal conditions were observed during the tests. The results of an experimental tensile study of PLA-plastic specimens are presented. The typical stress-strain diagram of an experimental sample is described, which describes the dependence of stress on relative deformation. An equation of the linear dependence of the tensile strength on the percentage of filament filling has been compiled, which makes it possible to determine the tensile strength of the product at any percentage of the filling of the plastic filament. The assessment is adequately verified by Fisher's criterion. Recommendations for filament filling in prototyping machine parts are given.

ADEQUACY OF THE MATHEMATICAL MODEL FOR DETERMINING RATIONAL CAPITAL INVESTMENTS

Purpose. Modeling today is one of the popular research methods related to increasing the efficiency of the functioning of rail transport units, because the model is a substitute for the original object that helps to study its properties. Compliance with the results obtained by model, the behavior of a real object is an important issue for modeling, so the adequacy verification is an integral part of this process. Therefore, the purpose of this article is to present a method for verifying the adequacy of the model of determination of rational investments in terms of sustainable development. Methodology. For models of dependence of the function of elasticity of investments in the directions of sustainable development on the characteristics of demand for services, checking for the adequacy on the basis of Fisher's criterion was carried out. For what zero hypothesis was formed on the equality of dispersion of inadequacy and dispersion of the experiment. Findings. The verification of models on adequacy has shown that the dependence of the functions of elasticity of investments in the areas of sustainable development from the parameters of demand for services adequately describes experimental results. Practical value. The performance of the adequacy of models confirmed the expediency of practical use of models in the management of railway transport depending units of the functions of elasticity of investments in the directions of sustainable development on the characteristics of demand for services of departments.

Mathematical Modeling of Process Optimization in Profiling Grinding Wheels via Laser

In this work, the experimental research was carried out on the processing of the cutting surface of a grinding wheel with a ceramic bond via continuous laser radiation with a wavelength of 10.6 μm. The influence of laser radiation power, processing speed on the depth and width of the obtained cut was investigated. A full factorial experiment was carried out with varying factors at two levels. In the form of a regression equation, a mathematical model of the effect of radiation power and processing speed on the output parameters of the process is obtained. Using Fisher's criterion, it is shown that the resulting equation adequately describes the process under the study. The analysis of the regression equation makes it possible to assess the relative influence of each factor and the effects of the interaction of factors on the depth and width of the cut on the surfaces of the grinding wheel.

Implementation of distance education at a medical university: an analysis of student satisfaction

Aim. Assessment of satisfaction of students of a medical university with the quality of distance learning. Materials and methods. A comparative prospective non-interventional study was conducted in December 2020 – January 2021, which included 167 students of the medical and prophylactic and pediatric faculties of the Ural State Medical University. Anonymous survey, submitted using the Google Forms platform, included answers to 18 open-ended questions with a choice of one or more answer options. Statistical analysis of the survey results was carried out on the basis of a summary of responses from the Google Forms platform, and Fisher’s criterion was also determined for nonparametric data. Results. When comparing the results of the questionnaire survey of students of the Ural State Medical University, it was found that three quarters of the students as a whole quite effectively adapted to the new conditions of on-line education, there were no significant differences in these indicators. Conducting classes in the format of video lessons, on-line testing and individual assignments on specific topics turned out to be the most welcomed by students forms of communication with teachers. At the same time, among the additional advantages of distance learning, students noted the possibility of combining study and work, the flexibility of the educational process and conducting classes in a comfortable home environment.

MULTI-FACTOR HEAT EXCHANGER DESIGN MODELS

Compressed air is widely used in enterprises, and it is possible to reduce air consumption on pneumatic devices by heating. Most often, heating is carried out in shell-and-tube heat exchangers. To increase the area of heat exchange between the heating medium and the air, finned tubes are used, which can significantly reduce the volume occupied by the heater. The design of the heater is influenced by many factors, and the importance of the influence of each of them can differ significantly. It is advisable to use the overall characteristic in the form of a compactness factor, which shows the ratio of the heat exchange area to the volume of the heater. The work developed a method for determining the optimal design of heaters by such a parameter as the compactness factor. The obtained regression equations make it possible to determine the influence of such factors as the number of rows of tubes across the flow and the length of one tube on the volume occupied by the heat exchanger and the compactness factor. According to Fisher's criterion, the equations of the model are adequate to the true dependence with a confidence level of 95%. Most of all, the volume of the heat exchanger and the compactness are affected by the number of tubes transverse to the air flow. Changing the length of one tube does not fundamentally affect the obtained values of the output parameters. With an increase in the length of one tube and their number across the flow, it is possible to achieve the highest values of the compactness coefficient, the dependence of which on the main factors has a pronounced maximum. Using the developed technique, it is possible, in a fairly simple formulation, to analyze the value of the compactness factor for various combinations of the above factors and to optimize the design of the heater.

STUDY OF THE MECHANICAL PROPERTIES OF THE FILAMENT DEPENDING ON THE PERCENTAGE OF FILLING WHEN PROTOTYPING THE PARTS OF MECHATRONIC COMPLEXES

The article contains an analysis of the applied thermoplastics used in prototyping parts of mechatronic complexes. Several types of experimental samples with different percent of filling are presented. Shown is the equipment on which the experimental studies were carried out. During the experiments, a specialized tensile testing machine was used. Experimental samples were installed in the developed centering device. Normal conditions were observed during the tests. The results of an experimental tensile study of PLA–plastic samples are presented. A characteristic stress–strain diagram of an experimental sample is described, which describes the dependence of stress on relative deformation. An equation of the linear dependence of the tensile strength on the percentage of filament filling has been compiled, which makes it possible to determine the ultimate strength of the product at any percentage of the filling of the plastic filament. Adequacy assessment is verified by Fisher's criterion. Recommendations are given on filament filling when prototyping machine parts.

Justification of the need to implement intelligent warehouse systems in fish processing

The paper reviews the existing state of fishing worldwide and in Bulgaria. Then the scheme is determined, according to which the live fish moves from the water basins in which it is raised and lives until it is sent to the store network and the end customers. As a result of the studies conducted, two-week points in the transitional warehouses have been identified. They are characterized by four main indexes: oxygen, temperature, Ph acidity and water level in the container. It these four are not within the determined allowances, it is possible the quality of the environment for storing the live fish to be deteriorated, which can lead to premature death of the fish. In this respect, a regression model with the four main indexes that are to be monitored and maintained within the allowance values has been created for achieving high quality of the storage environment. For the regression model has been determined a coefficient of determination R = 0.9131, and a Fisher’s criterion, which is 5.0143 compared to the one in the Table - 2.5802, which shows that the model is adequate and can be used for further calculations. For the practical solution of the problem, it has been proposed to introduce an intelligent information system in the transitional warehouses for storing live fish before the end processing. The system proposed will be used to monitor and control the four main indexes and to improve the conditions for storing live fish when it is moved along the chain of fish farms to the warehouses for end processing.

Modern Trends in the Functioning of Grain-Product Subcomplex of the Agricultural Sector of Ukraine in the Context of Implementing Its External Economic Potential

SummarySubject and purpose of work: The main purpose of the article is to research the state of grain-product subcomplex of the agro-industrial complex and identify the main trends in its functioning as a prerequisite for the implementation of the external economic potential of Ukraine.Materials and methods: The research used methodical tools for analysis, construction of econometric models, as well as open information sources of the State Statistics Service of Ukraine.Results: A set of factors (independent variables) were determined and the existence of theoretically their relationship with the production profitability of cereals and legumes (dependent variable) was substantiated. The regression equations for the investigated factors dependence were formed. The reliability of the econometric model was proved using Fisher’s criterion and Student’s t-criterion test.Conclusions: To increase the external economic potential of the grain-product subcomplex of the agro-industrial complex, it is advisable to focus on building rational mechanisms for managing the identified determinants of efficiency ensuring of the latter.

Face Recognition Using RLDA Method Based on Mutated Cuckoo Search Algorithm to Extract Optimal Features

Regularized-LDA (R-LDA) is one of the most successful holistic approaches that is introduced to overcome the “small sample size” (SSS) problem of the LDA method, which is often encountered in Face Recognition (FR) tasks. R-LDA is based on reducing the high variance of principal components of the within-class scatter matrix to optimize the regularized Fisher's criterion. In this article, the authors assume that some of these components do not have significant information and they can be discarded. To this end, the authors propose CS-RLDA that uses a Cuckoo search (CS) algorithm to select the optimal eigenvectors from a within-class matrix. However, the CS algorithm has a slow convergence speed. To deal with this problem, and to create more diversity and better trade-off between exploitation and exploration around the best solutions, the authors have modified the basic cuckoo algorithm by using a mutation operator. The experimental results performed on the ORL and UMIST databases indicate that the proposed method enhances the performance of FR.