The paper presents data on the results of computer-aided mathematical modeling and experimental studies of transient processes accompanying the start of asynchronous electric drives in order to search for the methods that enable the adjustment of a soft starter to achieve minimum oscillation amplitude of the electric motor dynamic momentum in terms of the current characteristic. The indicators of smoothness, applicable to some types of electric drives of turbine mechanisms, are revealed. It is found that the correlation between the maximum value of the starting current of the electric motor and the maximum amplitude of the momentum fluctuation, as well as between the starting time and the maximum amplitude of the momentum fluctuation, is insignificant. The most informative indicator, providing the function of adaptive self-tuning of the soft starter and maximum technical and economic efficiency of its use, is the oscillation of the dynamic momentum during the start-up. It is established that the amplitude of the dynamic momentum fluctuation can be judged by the displacement of the motor housing during start-up, which will require the modernization of the electric drive. The necessity of additionally calculating the implicit components of costs in terms of the costs of entrepreneurial risk when assessing the economic effect from the modernization of asynchronous electric drives using a soft starter is substantiated.
The article deals with issues related to increasing the efficiency of working with data on the geometry of the computational domain when solving hydrophysics problems using the finite difference method. The model problem is a system of equations of the pollutant distribution, including the oil and its refined products, in the computational domain – Azov Sea. To describe the computational domain, a model of a two-dimensional computational grid is used, which is used in the implementation of numerical calculations. Class diagrams are presented for describing the geometry of the object under study, as well as its constituent segments. In order to improve the performance of calculations, an algorithm for combining geometry segments was developed, in which the original algorithm was divided into separate fragments by introducing a number of conditional structures. As a result of experimental data processing, regression equations were obtained that describe the dependence of the algorithm execution time on the number of joins. The developed algorithm and class library make it possible to work with the description of the geometry of the object under study as a set of parameterized primitives and educe the time spent on the formation of the description of the computational domain by up to 27%.
Nowadays, organic farming is one of the innovative directions for the development of agricultural production. Its implementation is based on the principles of not using chemically synthesized fertilizers and plant protection products, but applying natural organic substances and creating conditions identical to the ones for natural plants growth. The most popular in this case are physical effects based on the conversion of electrical energy including conversion into light energy. It is well known that the use of optical radiation of the required intensity and duration makes it possible to stimulate intracellular processes in the seed and the plant itself. Such influencing factors primarily include ultraviolet radiation. Experimental studies to research the effect of pre-sowing treatment of tomato seeds “Rozoviy novichok” with radiation with a wavelength of 302, 313, 334 and 365 nm, exposure dose of 48; 72; 96 and 120 W s/m2 and a treatment time of 60 seconds revealed a positive effect. The highest germination of seeds, lengths of shoots and seed roots as well as the diameter of the stem and the dry weight of stems, leaves and roots were obtained at the indicated values of the wavelength and radiation dose. It should also be noted that at these values of the wavelength and radiation dose, the height of the seedlings is minimal, which means that the seedlings will be more stocky, and their survival rate will be maximum. This approach enables to formulate requirements for the design and development of a specialized electrotechnical installation for pre-sowing stimulation of such vegetable crops as tomatoes.
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