bluuebunny/crossref_metadata_2025_split huggingface dataset:
Methods of synthesis of energy-efficient structures for regulating semiconductor frequency converters
Authors: Bukhanov S S , Imanova A A , Kornienko M N , Zhuravleva L A , Fediakov V V 
Published: June 2019

Abstract
A mathematical model of the power part of the semiconductor converter was developed in this article. The analysis of processes in systems with synchronous electric drives. Experimental and analytical studies have shown that in electric drives with traditional synchronous motors with electromagnetic excitation it is necessary to take into account the influence of winding stray fluxes when setting up a control system. In electric drives with powers exceeding 1000 kW, the effect of leakage fluxes will increase significantly. Experimental methods have established that in multiphase electric drives, when the number of phases is greater than three, the influence of inductive scattering resistance can be neglected, and the mathematical model of the power section of a semiconductor converter is simplified. At the stages of adjustment, it is allowed to approximate the mathematical model of the system by sequential connection of aperiodic links of the first order, the time constants of which are specified during the study of frequency characteristics. The parameters of corrective relationships should also be refined by frequency response methods. Considered recommendations were successfully used in adjusting frequency converters for high-speed objects for LLC “RiK-Energo”.
Control of energy-efficient electric drive of pumping stations
Authors: Platonov Vladislav V , Tsirkunenko Anatoly T , Bukhanov Sergey S 
Published: June 2019

Abstract
The principles of pumping station control, providing the most efficient modes of operation are discussed in the article. To perform calculations of energy-efficient operation modes, a mathematical description of the system has been proposed. It is shown that the increase of energy efficiency in the system is achieved by choosing a power circuit, splitting up sections of the pumping station, selecting the appropriate operation algorithms for each of the sections. An electrical equivalent circuit of the control object is proposed. Comparison of the energy consumption of the pumping station was carried out for the following cases: in the first, the cascade did not work, and in the second, the flow was controlled in a cascade over the entire range of flow variation. It is established that the proposed control algorithms can significantly reduce energy consumption from the mains supply by about 30%.
The stages of development of high-performance adjustable AC drives for the objects of metallurgical production
Authors: Grigorev M A , Gryzlov A A , Katrichek V S 
Published: June 2019

Abstract
In the scientific article the requirements for regulated energy-efficient AC electric drives of metallurgical production facilities are formulated. The main stages of development of synchronous reluctance electric drives, including the development of power units, the synthesis of the control system, the choice of mathematical apparatus, as well as the experimental study of the developed system are shown. For the mechanism of a flying shear at PJSC “Chelyabinskiy metalurgicheskiy kombinat” the use of contactless synchronous electric drive with brushless salient pole rotor is most effective, as this allows you to implement over the time of 4-6 times of the rated value and the ability to work in chemically aggressive conditions. It is shown that the task of providing the trajectory of motion can be implemented only in systems with independent control over the excitation channel and the armature. It is shown that as a mathematical description of the system, the structure of the electric drive can be used, similar to the DC drive, but the control signals are supplied from the phase current formation node. The method of experimental research shows that the synthesis of current control circuits can be performed by frequency response methods. Analysis of the experimental current waveforms showed that the separate control of the armature and excitation current is realized independently, while the specific indicators of the system were better than synchronous frequency-controlled electric drives by about 25.
Financial losses of electric power industry, caused by corrosion wear designs lighting poles
Authors: Korobov Yuriy I , Muhambetov Serk B , Laskov Nikolay N , Shveikin Igor E , Chernykh Valentin K 
Published: June 2019

Abstract
Today, the total length of overhead power lines is very high. Supports for power lines and lighting lines exposed to corrosive wear. In this regard, the electricity sector is suffering huge economic losses. The article deals with the problem of the durability of the lighting line supports, reduce the economic costs of maintaining them. Are some of the results of experimental studies. The known methods for measuring the depth of corrosion on the power lines and light lines, as well as full-scale study designs. It is noted that during the survey revealed the specifics of building structures, which limits the possibility of restoring the protective coating in the field, which affects the financial costs. The methods of predicting the losses from corrosion, data observations. The contribution of corrosion losses in the increased likelihood of component failure and financial loss.
Differential twin-engine automobile electric drive
Authors: Belousov E V , Savosteenko N V , Funk T A , Denisova T V , Rumyantseva E A 
Published: June 2019

Abstract
This article considers work stability of a system with two-channel regulation of an autonomous electric drive’s speed, where the first channel is a high-torque drive, where the engine is connected through a gear unit with reducing transfer factor; and the second – high-speed with the similar motor is directly connected. The power summation is realized by using the differential gear unit. It is shown that the stable work can be achieved by a fixation of a speed setting through one channel, and the regulation through the other channel at the same time; control algorithms are shown. Optimal values of transmission ratio of high-torque drive gear unit j = 4 are defined, as well as a turn-on factor (rate of participation in transient process) of high-torque motor with its transient process time minimum.
Predictive model of the trunk oil pipeline technological section on the basis of results of transient conditions test
Authors: Agafonov E D , Mironov A G , Vashchenko G V , Kuklina A I 
Published: June 2019

Abstract
The paper deals with the problem of predicting the hydraulic parameters of the trunk oil pipeline (TOP) in transient operating practice. The requirements and assumptions for the model of the trunk oil pipeline are discussed. The basic differential equations describing hydraulic processes in the linear part of the TOP and pumping units are given. The paper analyzes the features of building models of trunk oil pipelines using the Matlab / SimHydraulics tool. As a result, a method for modifying standard Matlab / SimHydraulics tools for building TOP models was proposed. The TOP model “Omsk - Anzhero-Sudzhensk” was built using the modified features of the Matlab / SimHydraulics tool. A model quality criterion is proposed. Comparison of the results obtained in the TOP modeling with measurement data revealed the need to further adjust the model. Using optimization algorithms embedded in the Matlab package, the unknown parameters of the trunk oil pipeline model were adjusted according to the test of transient operating practice using the selected quality criterion.
Influence of thermal insulation from PUR foam to improve thermo-technical parameters of building envelope for broiler housing
Authors: Szabóová T , Balková M 
Published: June 2019

Abstract
The article deals with the thermo-technical assessment of a hall building for broiler breeding. There was a large heat losses in the examined object before the thermal insulation. For this reason, the cladding was from internal side insulated with sprayed PUR foam. In the building was assessed the hygiene criterion, thermo-technical properties of perimeter walls and the life of the structure before and after the insulation. It has been shown that the thermal insulation of the walls had a significant impact on improving the conditions in the hall. Due to the fact that from hygienic assessment and thermovision measurements have been proven heat losses and unsatisfactory condition of uninsulated parts of the hall envelope, it will be necessary to additionally insulate also the soffit part of the ceiling-roof construction and the plinth part.
Possibilities of use of glass recyclate from photovoltaic panels for concrete masonry units
Authors: Stehlík M , Knapová J , Kostka V 
Published: June 2019

Abstract
The paper deals with the possibilities of use of glass recyclate from photovoltaic panels for concrete masonry units. It compares different recipes and its physical and mechanical properties with the focus on the compressive strength, density. It then compares the values of these recipes with the values of commonly used composite materials for masonry units without recyclates. Recycling of materials from photovoltaic panels is a highly discussed topic nowadays. The paper presents possibility for secondary use of glass from these panels in building industry, namely the substitution of aggregate in concrete with glass recyclate.
Experimental determination of the influence of additives on shrinkage in self-compacting concrete
Authors: Alexa M , Kucharczyková B , Kocáb D , Daněk P 
Published: June 2019

Abstract
The paper deals with the influence of additives on the progress of shrinkage and mass losses in self-compacting concrete. Limestone and fly ash at varying amounts were used as an additive in the production of four types of self-compacting concrete. Volume changes were observed from an early stage of setting (the measurement was commenced within 1 hour of mixing) using shrinkage drains with a moveable wall, followed by a long-term manual measurement using an external strain gauge. For the first 48 hours the volume-change measurement was continuous, and for the next few months it was performed manually. Mass losses were determined simultaneously with shrinkage – during the first 48 hours by weighing on a special weighing table capable of continuous recording, and manually afterwards.
Non-destructive diagnostics of steel-reinforced concrete structures: detecting and locating reinforcement
Authors: Cikrle P , Hüblová S , Kocáb D , Karel O 
Published: June 2019

Abstract
The paper describes the possibilities of non-destructive determination of the location and depth of reinforcement in concrete structures using electromagnetic cover meters. It is currently one of the most popular methods for determining the location, cover depth and diameter of reinforcement. However, there are not many sources that would give a detailed description of specific measurement results. This paper describes the use of the Profometer PM-630 cover meter for in-situ measurement of a steel-reinforced-concrete road bridge deck. The paper details the results of measurements of cover depth, bends in reinforcement, and discusses the strong and weak points of the method.
Measurement of acoustic emission at fibre reinforcement concrete slab with subsoil
Authors: Sucharda O , Pazdera L , Marcalikova Z , Topolar L , Kozielova M , Bilek V 
Published: June 2019

Abstract
The paper deals with the possibility of using the acoustic emission (AE) measurement for the identification of cracks and failure in fibre concrete slabs in interaction with subsoil. In this specific task it is not possible to check visually cracking on the slab bottom surface. The research task included an experimental load test of a slab and supplemented laboratory testing to determine the mechanical properties of fibre concrete. The concrete used has a dosage of 25 kg/m3 fibres. Laboratory tests included cube and cylindrical compressive strength, flexural strength and split tensile strength. Homogeneity of the concrete mixture, i.e. uniform distribution of the fibres, was proven with testing of the split tensile strength both evenly and perpendicularly to the direction of filling the concrete mixture into the form. Experimental load test of slab on subsoil was performed on fibre concrete slab with plan dimensions 2000 x 2000 mm and thickness 150 mm. Concrete slab was loaded in the middle with force load step 75 kN. AE measurements were provided using track sensors.
An optimal method of determining the position of bends on shear reinforcement as part of the diagnosis of reinforced concrete beam structures
Authors: Anton O , Komárková T , Heřmánková V 
Published: June 2019

Abstract
The current period in the development of building industry can be characterized as a period of rapid development in this field, not only in the area of new constructions, but also in the area of a new uses of old constructions which find a new use after restoration, and as regards traffic facilities, especially bridge structures, in the area of verification of the existing functional characteristics and prediction of the lifetime of structures. This puts a strain on the field of diagnosis of structures, the development of which can be observed in the last 10 years in the form of a new wave of innovations of the existing NDT (non-destructive testing) methods as well as of the development of completely new devices and technologies. In spite of these facts, it can be said that in a number of cases, the diagnosis of structures is performed in traditional ways without using modern techniques and technologies. The aim of this paper is to present an optimal way of using NDT methods in the diagnosis of reinforced concrete beam structures, specifically in the determination of the position of shear bends on the main load-bearing reinforcement. The paper deals with the current state of the issue and illustrates, on a number of examples from practice, the applicability of individual methods as well as their limitations given by their physical principles and technological solutions.
Current possibilities of the diagnosis of prestressing steel in structures
Authors: Anton O , Cikrle P , Heřmánková V 
Published: June 2019

Abstract
The field of diagnosis of structures has been experiencing a dynamic development in the last decades caused by the development and expansion of new NDT methods and instrumentation. At the same time, it is possible to observe changes in the focus of interest in this field, or more precisely, alternating waves of interest in specific types of diagnosis targeted at special types of structures. These waves of interest are always caused by a certain trend in the development of the society or building industry, and most often, by some major even in the field. In the last few years, particular attention has been paid to prestressed structures, especially to bridges, in connection with the recent accidents of bridges made from prestressed concrete in the Czech Republic and abroad. Considering the relatively large number of these bridges in the Czech Republic built in the second half of the 20th century, attention is paid to basic changes in the pre-construction condition surveys aimed at determining the condition and the remaining life of these structures. The paper focuses on the analysis of possibilities of assessing the condition of prestressing steel at the level of the present state of diagnosis of structures.
An experimental preparation of fibre concrete to software’s detection of fibres
Authors: Gregorová V , Ďubek M , Ďubek S , Štefunková Z 
Published: June 2019

Abstract
Fibre concrete requirements are only met if the fibres in its volume are evenly distributed. Their direction and orientation should be equal around each axis in a three-dimensional space. The requirement is that the fibres to be evaluated in the final hardened fibre concrete are cut from fibre concrete sections. Homogeneity can also be verified on fibre-concrete cross-sections. Fibre Position Evaluation is a mathematical task that is not presented here but is currently made up of the results of this experiment. In the first step, it was necessary to prepare samples to obtain the necessary cross-sections. In the next step, it was necessary to create conditions by creating a contrast between the fibres and the concrete to create software capable of detecting fibres. In this paper, the principle of detection of fibres based on the detection of cut section images is described. There are several methods used to highlight the concrete matrix over the fibres. Also presented are the results of adding and detecting fibres.
Innovation of University education by using available online LCA methods and their role in construction sector
Authors: Ondova M , Estokova A , Wolfova M 
Published: June 2019

AbstractCurrently, active education at universities is increasingly preferred. The introduction of innovative approaches to teaching is reflected in the increased number of practical lectures mainly. The use of new methods has also been applied to the subject of "LCA Building Materials", which is aimed at assessing the environmental impacts of building materials. Regarding the production of building materials and their use, the process of construction and operation of the building, as well as its disposal, the use of environmental assessment methods seems to be very desirable and perspective in regard to negative impacts on the environment and public health. This idea formed the basis for an active approach to teaching. During the lectures, theoretical knowledge is continuously supplemented by an illustrative example of calculating the environmental impacts of a selected family house. Through the available online LCA methods students evaluate their projects in parallel with the teacher, as if they were dealing with a real contract. Main goals of the project are to improve students’ skills, to broaden their knowledge, to look at the issues comprehensively (construction industry, environmental protection, climate change etc.), and to apply knowledge to practice.
Presence of magnesium-alumina spinel in forsterite ceramics and its influence during sintering and on resulting properties of fired body
Authors: Nguyen M , Sokolář R 
Published: June 2019

Abstract
The main objective of this paper is to describe the creation and behaviour of magnesium-alumina spinel (MA-spinel) phase from raw materials mixtures in forsterite refractory and its influence on resulting physical properties and mineralogical composition of fired body. Forsterite ceramics is mostly used for its high refractoriness as a refractory material in kilns and furnaces and also in electrotechnical engineering for its high coefficient of linear thermal expansion for ceramic-metal joints. Currently, forsterite is not produced in the Czech Republic. The primary objective is to synthesize forsterite ceramics via solid-state reaction utilizing various raw materials used in industry with stoichiometric ratio of forsterite. The resulting properties of fired body will be determined using X-ray diffraction analysis for mineralogical composition, thermal dilatometric analysis and vacuum water absorption method for physical properties of fired body and refractoriness of pyrometric cones will be conducted.
Bulk density decreasing of lightweight silicate based composite
Authors: Meszarosova L , Drochytka R 
Published: June 2019

Abstract
The newly developed silicate composite combines advantages of two types of bulk density decreasing methods. Direct bulk density decreasing method is based on introduction of pores in the structure of binder and indirect bulk density decreasing is achieved by means of using fine grained porous aggregate. This combination makes it possible to achieve maximal decrease of bulk density of the mix. Material of this type shows very low bulk density, approx. 300 kg⋅m−3 and appropriate application would be for non-structural, filling material or insulating material. Achieved results will serve as base for further modification of mix-design of aerated concrete utilizing secondary raw materials.
Polymer based grout with specially treated hazardous waste
Authors: Žlebek T , Hodul J , Drochytka R 
Published: June 2019

Abstract
The present research verified the possibility of using specially treated hazardous waste (solidification product) derived from a solidification agent (fly ash from fluidized bed combustion (FA)) and hazardous waste (end-product) as a filler in polymeric grout. Hazardous waste was pre-treated by solidification technology, while within the performed research, a total of two solidification paths were verified. One of them was a dry homogenisation (TOS1) and the other technology was wet granulation of the input materials (TOS2). The use of dry homogenization solidification technology, which is economically less demanding, seems to be more advantageous. Using such specially treated filler was verified by some selected tests and the results indicated grout with a relatively high compressive strength of about 50 MPa and a flexural strength of about 20 MPa. The developed polymeric grout also showed a very good adhesion to a cast basalt, which was tested by the pull-off test and subsequently observed in detail by optical microscope.
Possibilities of evaluation of the masonry wall affected by the explosion
Authors: Schmid P , Láník J , Žítt P , Halašta L , Čalkovský P , Bartošková M 
Published: June 2019

Abstract
At present, emphasis is placed on the safety and durability of building structures due to the effects of external loads. Among the various external influences of the load, we can also include loads caused by the blast wave. Structures subjected to extreme loads such as explosion are structurally disrupted in a manner different from that of static or dynamic external loads. In construction practice, we are sometimes faced with the question of how to evaluate the state of a structure after an explosion. The article is focused on the possibility of evaluating the masonry wall affected by the explosion in terms of the expression of residual bearing capacity based on the laboratory tests and inspection in-situ.
Biodegradation and its impact on durability of building construction
Authors: Terpakova E , Estokova A 
Published: June 2019

Abstract
The durability of building elements is influenced by a number of different factors. Among the most complicated, biocorrosion can be included without exaggeration. From practical experience, we know that biodegradation manifests itself in all kinds of materials and structural elements. Although both primary and secondary protection of a particular building structure is realized, if appropriate living conditions are created for the existence of a particular species of biodeteriogen, this kind of degradation will be initiated. The paper deals with the issue of biocorrosion, which was studied at selected parts of the technical extension in Campus of the Technical University in Košice. Undesirable bio-corrosive symptoms due to the presence of algae and fungi are often visually observed on the surfaces, but their effects also have a negative impact on the internal structure. In practical terms, a solution to identification of these symptom are required which needs to develop methods of monitoring the state of the surface over time and removing them. Diagnostic methods will be presented to check the technical state condition of construction parts as support in identification bio-corrosion symptoms.