To limit the inrush currents in the stator windings, various schemes for starting an asynchronous electric motor are used. In addition, the existing devices have a complex control system, which creates certain difficulties in installation and operation. But the analysis of scientific literature and materials from certain sources testifies to the insufficient study of this problem. In scientific work, the advantages and disadvantages of a new type of contactless starter are compared with contact and non-contact starters of various types. An original circuit of a new type of thyristor starter with a simplified design has been developed and manufactured, which has the ability to smoothly start and control the power consumption of asynchronous machines. Computer simulation of a new type of contactless starter with pulse-width modulation control in the Matlab Simulink program has been carried out: a pulse current is supplied to the controlled thyristor electrode on the basis of the pulse-width modulation control and the thyristor opens and passes the current, the resistance is set to decrease the input signal level. The design of the proposed starter is based on the combination of a thyristor starter with logical control, which has the ability to smoothly start and remote control of the power consumption of asynchronous electric motors, which has the ability to save energy and resources. Modern methods of implementing a logical control system, a pulse current generator with RLC filters, are proposed, and the task of remote monitoring and control of power consumption of asynchronouselectricmotors is set.
An analysis of the dynamic response of an underground main pipeline under a longitudinal wave propagating in soil along the pipe is given in the article. The problem of the longitudinal wave impact on a pipeline of finite length, interacting with soil according to the elastic-viscous law, is considered. The ends of the pipeline are fixed to massive nodes that interact with the medium according to linear laws. Along the length of the pipeline, the coefficients of the elastic and viscous pipeline-soil interaction change depending on the coordinate. In this article, the influence of the coefficients of elastic and viscous interaction of the "pipe-soil" system is studied when these coefficients are coordinate functions. The variability of the values of the coefficients along the length of the pipeline leads to a change in displacements from 0 to 15% and strain from 0 to 18%, compared with the case when these coefficients are constant. Depending on the length of the pipeline, the response of the pipeline to seismic action is different. This is especially evident at the boundary points. Considering the weight of nodes leads largely to a decrease in the strain of the pipeline relative to the soil strain at the boundary points.
The aim of the study is to study the effect of gas pyrolysis resin on the properties of elastomeric composite materials. It has been established that in the presence of it in the thiuram vulcanizing system, the relative rate of vulcanization of styrene-butadiene rubber increases, the time to reach the optimum vulcanization decreases, but the degree of vulcanization decreases, proportional to the maximum torque, and when using a sulfur vulcanizing system, it activates the vulcanization process, which is facilitated by the presence in its composition of active functional groups (-OH, -COOH, etc.). It is shown that the tensile strength and relative elongation of the vulcanizates increase, while the elasticity remains at an average level.
It is important to research the dependence of the capacitance and capacitance on the parameters on the photodiodes. In this article, we aim research experimental and theoretical on the nCdSpSi heterostructure. A heavily doped n+CdS layer with a thickness of about 50 Å was created by deposition of a thin layer of indium (In) for 25-30 s on the surface of a CdS film in vacuum with a residual pressure of 10-5Torr at a substrate temperature of 373 K, followed by annealing at 673 K in within 300s. Then, on the surface of this heavily doped n+CdS layer, a current-collecting “P”-shaped ohmic contact with an area of 3 mm2 was obtained also by the vacuum evaporation of In.
The article examines forensic research of state, departmental and other awards: orders, medals, badges of honor. The importance and results of a set of methods commonly used in forensic research in their study are described. The main rules of the methodology and the possibilities of each of the specified types of expertise in relation to these objects, as well as the requirements for experts are given.
The article presents the results of the study of the multistage information-measuring system (IMS) of the diagnostic of traction power supply objects combined with the operational-dispatch control allowing to ensure reliability, attributing to unit value of the IMS. Taking into account the introduction of functional redundancy in the structure of duplicate channels of diagnostics of each stage. he upper level of the complex should maintain processing of information received more frequently from previous devices and issue of certain tasks to the operating personnel for the work of maintenance according to the actual condition of the diagnosed facility. Based on mathematical models of reliability of primary converters and information processing devices on probabilistic indicators. The functional block-circuits of the multi-stage IMS for obtaining and converting information on the example of power transformer diagnostics and contact network devices are disclosed. It has been shown that, given the vulnerability of communication channels, it is advisable to transmit information in large flows, for example, related to spectral analysis, to process at the lower stages of the IMS, and through communication channels to transmit their integral indicators.
This article describes how the historians of the Temurid epoch created cultural andscientific foundations, gardens, buildings, cultural objects, water facilities, canals and arches, schools, madrasas, mosques, hospitals, bathhouses, rabbats and caravan serais,promoting social cultural development of the state, their charitable activities and sponsorship
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