Physics and Mathematics
Methods of integrated optimization of transport networks are developed. They are based on their approximation by non-Markov networks of queuing with multi-linear nodes (roads), the speed of which decreases with increasing load. The proposed methods are oriented to different modes of transport load. Examples of the application of the proposed methods are given. It is demonstrated that the greatest effect in combating blockings is provided by the integrated optimization of transport networks oriented to the regime of high transport load.
The article describes the deduced formula for the three-dimensional model of a composite cage material in a stress-strain state. The paper presents the formula for reactive lateral compression from a composite cage to a concrete. The analytical solution to the problem of compressing a concrete column in a composite cage taking into account the nonlinear behavior of concrete is obtained. The increases in the loadbearing capacity of the concrete column in steel and composite basalt-plastic cages are compared.
It brings us to the conclusion that the use of composite cage in concrete-filled steel tube structures is a promising direction for further research and that it is necessary to use fibers having higher deformation characteristics.
The author resolved an issue of finding a particle reflection probability from the medium. Mathematical simulation of this task is given, mathematical solutions of finding a particle reflection probability from the nonuniform medium are provided. The mathematical description of the designated tasks allows solving more complex problems of random walks in the continuous anisotropic medium. Pure scattering is also considered and the corresponding formulas are obtained.
The proposed simulator concept involves the development of a complex simulator for training a team of control operators (for example, operators of a multi-stage oil refining process). Simulations should be performed with a visual simulation of the production by mnemonic diagrams, providing operators with the necessary information, as well as supporting them in decisions making using indicators, audio signals and information messages. Time parameters of operators’ interaction and criteria of quality control are assumed to be estimated to analyze the quality of operators’ teamwork.
Engeneering
The task of calculating the resonant frequencies is relevant in the design of printed circuit assemblies structures of onboard electronic devices. Analysis of the amplitude-frequency characteristics based on the estimated values of the resonant frequencies and their subsequent analysis is indicative of the technical condition of the object of study.
All geometrical dimensions of the structural elements of the electronic device and the location of the electronic components on the printed circuit board have to meet the tolerances specified in the design documentation. It is impossible to maintain an exact technology during production, therefore all parameters may have tolerance limits.
Any changes in the parameters of the printed circuit assembly within the tolerance leads to a variation of the resonant frequencies relative to the idealized value, therefore forming the tolerance intervals of the resonant frequencies.
The paper describes the methods for calculating the diversities of the printed circuit resonant frequencies: experimental, the worst case method, the method of moments and the Monte Carlo method. The analysis of the features of each method is made. It is proposed to use the Monte Carlo method, as having the greatest accuracy and ease of implementation, taking into account the computational capabilities of modern electronic computers.
A block diagram of the Monte Carlo method application is proposed, the mathematical apparatus is presented. The process of integrating software systems for calculating the diversities of the resonant frequencies of a printed circuit assembly is described.
A comparative analysis of the speed for the proposed method and the method based on the analysis of system tables is carried out using test sets of random data.
The usage of the tensor representation of the information system's databases allows obtaining a compact mathematical description, and the binary coding of the relational model entities allows simplifying the programmatic access to the integrated data storage. Experimentally confirmed that the sample contains more than 15 000 records, the tensor representation of the data storage allows shortening the time of execution from 25 % to 11 500 %.
PiktoMir allows performing not only the individual but also team (joint) programming tasks. Each team member individually works on his part of the program on his computer during a team task, which makes it possible to objectively evaluate the contribution of each team member to the overall collective result. Cooperative programming can be used both in the regular programming course and for conducting team competitions.