№ 131(7), September, 2017
Public date: 29.09.2017
Archive of journal: Articles count 124, 307 kb
-
OBTAINING OF FREQUENCY CHARACTERISTICS FOR INDUCTION MOTORS USING THE RESULTS OF THE EXPERIMENT
Description
The article is devoted to the solution of the urgent task, which is to increase the reliability of the power supply systems of enterprises for processing agricultural products. The material of the article has a research character, which consists in the fact that the obtained expressions for the frequency characteristics of high-voltage induction motors allow us to investigate the symmetric modes of their operation by means of a more efficient and simple apparatus. A number of provisions of the article have a scientific novelty, which consists in obtaining frequency characteristics for induction motors as a result of the experiment. A convenient procedure for obtaining the frequency response of an induction motor based on the results of an experiment using the mathematical model of an induction motor in the coordinates of the generalized vector and the Fourier transform has been developed. As an example, oscillograms of the stator current of an induction motor of the A-12-52-4 type are given for the initial stage of the start-up. For the stator current of this induction motor, a transition is made from the phase coordinate system to the coordinates of the generalized vector. The dependences of the stator current on the D and Q axes on time are constructed. The real and imaginary parts of the frequency characteristic of the engine are calculated for sliding s = 1, the calculations are illustrated by the corresponding graphical characteristics. The results of the study are proposed to be used for the calculation of transients in power supply systems for enterprises engaged in the processing of agricultural products
-
A METHOD OF CALCULATING THE COMBINE PARK IN VARIOUS CONDITIONS OF CLEANING
Description
The article discusses the technique of calculating the combine harvester under various harvesting conditions. The authors consider two options for optimizing the fleet of combines: the first, when the harvested area is set, the second, when the harvested area is not specified. In the first case, the harvester park is calculated for a known area with different harvesting times, but within the boundaries of the agro-industry. In the second variant, a park of harvesters is justified and it is calculated how much space it will be able to clean for a different duration of harvesting operations
-
WAYS TO PROVIDE STABILITY OF RAW MATERIAL DURING STORAGE
Description
The article analyzes the ways of ensuring a stable quality of fruit in the process of storage. The patented methods of storage, realization of which allows increasing of storage life of agricultural products by means of using low temperatures, regulating the content of gaseous medium in the storage, creating hermetic storing conditions, treating with chemical substances, using biopreparations, were systematized. The analysis of literature sources and patent information has show that the development of methods for storing plant raw materials with using biopreparations is up-to-date
-
APPROBATION OF THE SUBSTANTIATION METHODS OF THE INTERNATIONAL TIMBER TRANSPORTATION PROCESS
Description
Modern small logging enterprises exporting timber primarily by lorry transport do not have resources for implementing research that contributes to reducing the cost of this type of transport. Besides, there is no universal and accessible planning methodology and operative decision-making in the organization of timber export by lorry transport. Because of this, the author of the article has proposed a methodology for improving international timber transportation by timber trucks. This methodology contains logging modeling simulation, as well as analysis and contain of different options of logging. Within the framework of this methodology, a unique model based on the discrete event simulation has been developed. This model simulates a full cycle of timber transportation from the terminal to several foreign consumers. The working capacity of the model was verified by simulating several export scenarios based on data obtained during field study at one of the logging enterprises, the annual logging volume of which is 400 thousand cubic meters. The analysis and comparison of the modeling results have confirmed the possibility of using this methodology in planning and organizing international timber transportation for small logging enterprises
-
CONSTRUCTING A MATHEMATICAL MODEL OF PRICING FOR REAL ESTATE IN KRASNODAR
Description
This study proposes a method of determining the cost of 1 sq. m. apartment on the example of Krasnodar, which is especially important in connection with the necessity of reliable and valid assessment of the property value in a modern market economy. We have performed an analysis of data on apartments in Krasnodar from the site of the Regional Energy Commission - prices and tariffs department of the Krasnodar region. We have also had an exploratory analysis of available data on the subject of emissions and insignificant data (by constructing line graphs and scatter plots); we have also checked for possible dependencies between observations and between variables (built correlation matrix). We have selected variables is linear, the regression model for the variable "cost of 1 sq. m the total area, ths. rub. "(multiple regression). Using regression analysis as a method of mathematical statistics we have revealed a form of analytical dependence of the result of the predictor variables and the degree of this dependence
-
MODULAR POWER SUPPLY WITH CONFIGURABLE STRUCTURE
Description
In this article, we consider problems of power supply of modern electronic devices. The author proposes a new concept of source of power, which resolves this problem. In addition, this article describes limitations of existing desertions in the area of power supply. In the article, we suggest ways of resolving this limitation by creating a new source of power based on principles, which are different from the existing way. In this article, we develop a theory of creating a universal modular source of power, which would have some advantages. This article considers an optimal structural scheme of that source. We have developed a source of power which meets the requirements of power supply of modern electronic devices and has a potential supply for the next development
-
Description
It is estimated that (85-95%) of the electric motor failures occur due to damage to the stator winding. In this case, more than 90% of damage are because of interturn short circuits. Short circuits in stator windings of stand-alone asynchronous generator change the base magnetic flux incidentally, so the probability of its long work with such kind of damage is great. A latent failure, existing as a loop closure, significantly reduces the reliability of the generator as a backup power source. Now sensitive protections of asynchronous generators do not exist, since it is believed that in the case of short circuits (short circuit), the generator loses its excitation, and protection is not required for it. Identification of information signs of short-circuit currents in the stator winding of an asynchronous generator makes it possible to develop relay protection. The main principle of detection of stokes closures in the stator winding of an asynchronous electric motor is the measurement of the emerging asymmetry of the stator currents. It has been established that in the case of short-circuit faults, the asymmetry of the currents and voltages is not large and comparable to the asymmetry in the AAG load circuit. This does not allow performing a protection that reacts to this asymmetry. You can also say about changing the harmonic spectrum of currents and voltages. To build protection, it is necessary to use highly sensitive circuits for detecting the asymmetry of a three-phase system of currents and voltages, as well as distortion of the shape of currents and voltages, for example, by harmonic analysis. Do not exclude the possibility of using other protection devices, such as reacting the vibration of the case of an induction generator in the event of damage to the stator winding
-
MONITORING OF THE EFFICIENCY OF ASH CATCHING AT NOVOCHERKASSK SDPP
Description
The electric method of gas dedusting is the most effective, since it allows capturing solid particles with a size from 0.01 µm to tens of microns. The efficiency of dust and gas cleaning equipment of Novocherkassk SDPP for cleaning flue gases from ash at power units 1-7 in the period from February 2015 to February 2017 is considered. The main equipment is electrostatic precipitators. As a solid fuel, Donetsk culm is used. It is established that the efficiency of waste gas purification at power units 5-7 was about 99 %, while at power units from the 1st to the 4th this value was within 95-96 %. The data obtained correspond to the design data, but it is recommended that the cleaning devices be improved to improve their efficiency. The most acceptable is a combined electrofilter-bag filter
-
TECHNOLOGY AND APPLICATION OF POWDERED FOOD ADDITIVES FROM VEGETABLE RAW MATERIALS
Description
The market for functional food products is continuously increasing and, according to analysts, by 2020 its share will reach 40% of all food products. The development of the healthy food has been gathering momentum in recent years, the search for non-traditional types of raw materials is constantly being conducted, and new recipes for products enriched with natural food additives are being created. In this regard, special attention is paid to the production and use of powdered food additives from plant raw materials. Theoretical significance and practical applicability of powder technologies in different years was substantiated by such famous scientists as Deryagin B.V., Donchenko L.V., Zimon A.D., Zubchenko A.V., Kasyanov G.I., Magomedov G.О., Paschenko L.P., Rebinder P.A., Tilesnik M.A., Yankhin E.D. In their opinion, using natural food additives, it is possible to obtain functional food products with specified chemical composition and properties. The objects of our research were apricot, grape seeds, pumpkin flesh, black currant and seabuckthorn berries, spinach, apples and flour from lowfat barley. In the course of the study, the effect of dispersity of the obtained powders on their antioxidant activity and frictional properties was studied. The expediency of introducing powders into the composition of multicomponent food products for enriching them with carbohydrates, vitamins and microelements is shown. The organoleptic evaluation of the produced powders showed that they have high taste values. The study of organoleptic and microbiological indices of products enriched with such powders indicates prolongation of their shelf life. As the main results of the study, we note the assessment of the chemical composition of the powders from the investigated objects, as well as the improvement of the technology of drying of plant raw materials with sparing technological regimes of its implementation
-
COMBINATORIAL DIAGNOSIS MODEL OF A POWER OBJECT
Description
The present level of development of power systems, the need to increase their resources and increased competition have caused especially true problem of increasing the efficiency of their operation. The work is devoted to the justification of the selection and development of a technique of construction of the diagnostic model to search for failures in power objects
pdf 295.035kb
doc 295.035kb