05.00.00 Technical science
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OBTAINING OF FREQUENCY CHARACTERISTICS FOR INDUCTION MOTORS USING THE RESULTS OF THE EXPERIMENT
DescriptionThe 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
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Description
This article is devoted to the problems of the improvement of foodstuffs quality as a component of food security of the country and its regions. The analysis of the difficulties of domestic producers of foodstuffs associated with the imperfection of the regulatory framework is made. Insufficient supply of good quality foodstuffs can significantly affect the well-being of the population, the health of the nation, the sustainable economic growth of the country, its financial stability, and overall economic security of Russia. The priorities of the Strategy of improving the foodstuffs quality till 2030 are given; the main of those ones is the organization of monitoring over the foodstuffs quality in security issues, power, food and biological value, as well as in the field of consumer characteristics (appearance, marking, etc.)
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Description
Waterflooding helps in the recovery of great amount of oil that would have otherwise been abandoned in the reservoir that is depleted. A reservoir in the Niger Delta, Reservoir X has been used to illustrate this. Reservoir X had oil initially in place as 7.345 MMSTB and was produced for some time with the reservoir natural energy. The remaining oil in the reservoir as at the time that the natural energy of the reservoir was no more sufficient to produce oil was 2.96MMSTB. The reservoir has been left as depleted reservoir with the remaining oil in it. But from the analysis conducted in this work it is seen that if secondary oil recovery project by waterflooding is embarked on the reservoir, part of the remaining abandoned oil would be recovered. With the specifications given, about 1.22MMSTB of the 2.96MMSTB of oil in reservoir X would be produced as at the breakthrough time of 580 days. Moreover, considering the economic aspect of the project, reservoir X and is good to be invested in. From the NPV calculations performed, it is seen that the NPV of reservoir X at discount rate of 10% is $4.13 million
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Description
The article reveals the basic principle of stabilizing the DC voltage, providing automatic control of electrical devices and electrical equipment, control systems, control and protection, etc. There are functional diagrams (operated and promising) of DC voltage stabilization with a device included in the input and output power circuits of the rectifier, and a new structural solution to a functional circuit of the rectifier made of two controllable power electronic devices and transformer with midpoint. The article lists peculiarities of the circuits of the voltage regulators and their main advantages and disadvantages. We have reviewed functional diagrams of existing and new solutions of the stabilizers and the characteristics of their work; it will increase the effectiveness of pre-project works on the development of stabilizers of the DC voltage with improved performance characteristics. This article might be useful for post-graduates and research workers who are involved in the development of DC voltage stabilizers
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Description
Now in different branches of the industry there is a need for the new equipment and mechanisms with the seized characteristics. Special requirements are shown to energetic and mass-dimensional indices of systems of electric drives as one of the main components of such devices. Mass-dimensional and energetic indices due to constructional features and the used management system will allow improving use of special or controlled asynchronous cascade systems of an electric actuator of cylindrical construction. One of the main difficulties is simulation and design of special systems of the electric drive. In this article, a new approach to determination of magnetic model parameters of the stator of a component of the controlled asynchronous cascade electrical drive of cylindrical construction is offered
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Description
Improvement is offered for working bodies’ forms in devices for preparation of forages by methods of engineering geometry and computer graphics. That opens not only great opportunities for intensification, increase in productivity and efficiency of the technological processes, but also opens ways for creation of small-sized devices for their realization. Constructive study of geometry of working bodies surface, allows us to give wavy movement to particles of forage and impart them the movement with bigger power consumption. In such installations forage particles components, meeting walls of working body, change their direction and, meeting other portions of particles of forage components, mix up. From loading to unloading, throughout the installations working body length, flexible and strong waves of forage particles components movement inside the working body are born. The conducted pilot studies have shown that as a result of working bodies’ forms improvement of devices for preparation of forages by methods of descriptive geometry such devices can be implemented in a variety of industries
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PARAMETRIC IDENTIFICATION OF THE PROCESS OF DRYING CORRUGATED BOARD
DescriptionThe article identifies the unknown parameters of the transfer functions of governing and operating channels of the control object. To do this, we have carried out processing of results of experiments. It is shown that there is not only dynamic but also static nonlinearity of the control object, expressed in physically less persistence processes increase the pressure by increasing the opening of the steam regulating valve compared with the opposite processes
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RESEARCH THE FILLING PILE’S SETTLEMENT IN CLAY SOILS DURING REPEATED STATIC LOADING
DescriptionThe object of the study is bored piles and their joint work with clay soils. The analysis of the field of static tests of bored piles, arranged by continuous flight auger technology (CFA), was carried out by repeated loading. Curve of settlement and the rate of its development from the applied force was obtained. Linear relationship reducing the amount of settlement in the second cycle from residual displacements after unloading pile on the first cycle was found. There was a relationship increment of settlements in the second cycle from the involvement of the bottom end in the work
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BUILDING AN EMPIRICAL DEPENDENCE OF THE GRANULOMETRIC COMPOSITION OF FOUNDRY DUST
DescriptionThe article considers the model of granulometric composition of foundry dust. We used the method of particle size analysis, which is based on the dependence between the size and the velocity of a body under the action of gravitational or centrifugal forces. Determination of granulometric composition of the given sample of powder was made using the laser diffraction method, implemented on a laser particle analyzer, Fritsch NanoTec “ANALISETTE 22”. A model of dust particle size distribution has been obtained
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Description
The work is done in scientific and practical directions for minimization of power losses in transmission of electricity to local distribution networks between the actors of the energy (producers and consumers) of energy-saving technologies focused on technological activities such as modernization and reconstruction of networks. Quite often in various circuits of power systems, it is advisable to transfer energy and its power through intermediate (transit) nodes. Structural changes in the electricity sector, at present, are mainly associated with the introduction of market relations between the subjects of energy exchange; therefore, in this work special attention is paid to the problem of calculating the power losses, as it is nonlinearly dependent on the power at the nodes and branches of a network. It should be noted that the nodes in problems transit capacity could be both sources and consumers. The latter necessitated the need for search of possible ways to reduce transportation losses of energy due to both the improvement and optimization of distribution networks and through the use of intermediate transit nodes. It follows that the transportation problem in this formulation is more General and expands the possibilities of optimization of power losses for the local subsystems of the energy clusters. The work is composed of the transport matrix for solving problems transit capacity, where the algorithm taking into account the distinctive features of which consist in the use of continuous numbering of sources and consumers in the matrix, and any node can be a transit country. The transit capacity ii-th node Zii=0, and the dimension of the matrix in contrast to the previously considered tasks has (n+m) (n+m) and it remains square as all the transport problems of linear programming. Transit variables Xii are included in the solution of the problem with a minus sign, and all transit variables are considered basic. From the above example in the work of a number of branches of a network is minimal, which significantly reduces the cost of building and maintaining the network, and the solver minimizes the power loss between the subjects of energy exchange and, as a result to savings from the standpoint of cost of construction of the network and the management of overflows of energy in it