№ 107(3), March, 2015
Public date: 31.03.2015
Archive of journal: Articles count 114, 263 kb
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STUDY OF POLYMERIC MATERIALS PERFORMANCE IN FRICTION CONDITIONS WITH ICE AND SNOW
Description
The problem of identifying of the most promising polymer materials for sledge sliding application. The comparison of materials is given: the bench tests of polyethylene, fluoroplast, steel and ultra high molecular weight polyethylene (UHMWPE) with different molecular weight and their composites are carried out. On the basis of research of polymeric samples on ice and snow friction in exploiting condition with the use of specially designed sledges was shown that GUR 4150 UHMWPE has the lowest mass volume and linear wear. Also in article the results of research of ice adhesion to different materials are presented. Adhesion research was carried out in low temperature conditions of air from -21oC up to -46oC and in cryocamera according method which was patented by Institute of oil and gas problems of SB RAS. The research showed that GUR 4150 UHMWPE has the lowest adhesion to ice. On the basis of obtained data the authors assumed that GUR 4150 is the most perspective materials for development of sledge sliding exploiting in Arctic conditions.
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Description
Based on the analysis of the phase composition, the average grain size measured by high resolution electron microscopy and multifractal parameterization structure shows the relationship of coating properties with their structural-phase state. The regularities of the evolution of the structural parameters and multifractal characteristics of the surface layers of materials with shape memory can predict the properties of the composition of the "steel-coating". On the basis of experimental studies, it has been shown that mechanical activation of powders of materials with shape memory effect based on TiNiTa makes it possible to create an effective technology training sprayed material which will generate nano-structured surface layers by high-speed flame spraying. The influence of the mechanical activation of TiNiTa powder on the quality of surface layers formed by high-speed flame spraying was investigated, and a significant improvement in the structure of the surface layer was found, with reduced porosity, high adhesion, and, consequently, increased functionality and mechanical properties. The evolution of the structure at all stages of surface modification based on the fractal approach multifractal parameterization method, which is based on qualitative analysis and instrumental methods in addition to classic microstructure parameters like grain size and specific area related to the physical and mechanical properties, is quantitative information. It was established experimentally that after high-speed flame spraying, the performance characteristics of mechanically activated shape memory TiNiTa powder improved: cyclic durability under high-cycle fatigue increased by about 35.6%, and the wear resistance increased by 3.6 times
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MODULE HOUSE AS A PERSPECTIVE FOR FARMERS
Description
In 2014 citizens of Russia felt the whole power of the introduction of reciprocal sanctions. Since 2014 the import of pork from the European Union has been limited and since August this has happened with poultry meat from EU and the USA. These actions led to the shortage of meat raw and rise of prices on meat produce in some regions of Russia. In spite of it, many business owners positively assess the possibility of full substitution of imported raw products. The government of the Russian Federation is ready to invest the projects for substitution of import products. In the conditions of crediting with credit rate of 25% the construction of small and average companies will be too heavy for rising. The construction of even small processing enterprise takes much time and powers. In connection with it, one of the perspective ways of the decision of this problem is the use of module houses of small and average power. Such houses allow processing meat and fish of small amounts. In comparison with capital construction the installation of a module house demands only specific areas, supply of electrical energy, water and withdrawal of sewage. There were considered the examples of module houses with the description of equipment and constructive peculiarities in the article. There were cited the advantages and the disadvantages of the offered module houses. There were formulated the recommendations on using already existing companies
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Description
The most important physical properties that characterize the substance are density and saturated vapor pressure (SVP). These parameters are required for the development of new technical processes in the petroleum and chemical industries, design of pipelines, pumping and fuel equipment, etc. Existing methods for calculating of density near and on the saturation lines are imperfect, and finding of the analytic dependence of SVP of petroleum products from all defining parameters associated with great difficulties. The purpose of present work is an experimental research and development of methods for calculating the density (specific volume) near and on saturation lines, and saturated vapor pressure of gasoline straight-run fraction derived from petroleums from three fields: Mangyshlaksky, Trinity-Anastasevsky and West Siberian. The choice of objects for research is due to the necessity of creating methods for calculating of density and SVP of oils obtained from various hydrocarbon group composition petroleums. Area of state parameters in the present work by temperature (20 ÷ 320°C) and pressure (0,03 ÷ 30 MPa) provides the ability to research gasoline fractions to supercritical regions. Measurement of density and SVP of petroleum fractions performed with help of a specially created for this purpose experimental installation
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Description
The article describes the methods of calibration and working measurements, planning of experiment and experimental data processing, characterized objects of study and provides illustrations of research results of P-t depending for petroleum fractions. We have described the results of generalization of density (specific volume) of the examined samples in the liquid and on the saturation line and SVP in the two-phase region. The article shows that existing methods of calculation based primarily on the results of the study of the density and SVP of individual hydrocarbons and extremely limited experimental data of petroleum products. We have detected a necessity of creation calculation methods based on reliable experimental data, providing greater accuracy, substantiated choice of directions for research SVP and density of petroleum products. Modern technology of petroleum processing and using of petroleum products requires the creation of more perfect installation for the study of SVP of substances and obtaining experimental data with greater accuracy. Generalized analytic dependence of SVP of petroleum products from all determining parameters have not yet been received. Therefore, experimental determination of this pressure should be the basis of the calculation of any device, because the calculations of petroleum products by the formulas and nomograms obtained with considerable error
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ESTIMATION OF BEARING STRENGTH OF BRACES AND STRUTS OF FARMS OF COVERAGE OF 6D TYPE HOTHOUSES
Description
The method of estimation of bearing strength of braces and struts of farms of coverage of hothouses is presented in the article. The deep analysis of the question of bearing strength appeared in the light of mass erection of hothouses, especially in the South Federal district, the construction of which had been bought in the countries of Near East. However, simple transfer of the constructions of hothouses made in foreign countries can not be considered as rational on the territory of the Russian Federation. The constructions of hothouses in most do not maintain exploitation even in one winter, when the considerable snow loadings are, and wind as well. The necessity of bringing of clarity for the folded situation became more obvious. Conducted successive static, dynamic and seismic analyses, executed upon the normative documents and due to the norms of supplier operating on the territory of the Russian Federation, in attachment to the real sections of bearings structural elements, allowed to expose the stated below percents of the use of the examined elements of constructions. Supporting braces of farms of coverage: on the norms of the Russian Federation, on the first maximum state percent of the use – 999 %; there is a percent of the use on the second maximum state – 999 %; on the norms of the Russian Federation taking into account loadings of supplier, on the first maximum state percent of the use – 999 %; there is a percent of the use on the second maximum state – 999 %; Stretched braces of farms of coverage: on the norms of the Russian Federation, on the first maximum state percent of the use – 64,2%; there is a percent of the use on the second maximum state – 721,8 %; on the norms of the Russian Federation taking into account loadings of supplier, on the first maximum state percent of the use – 25,8 %; there is a percent of the use on the second maximum state – 721,8%. Analysis presented allows establishing that at the load of supporting, stretched and central braces of farms of coverage of hothouses, by combinations of loadings characteristic for the place of location of hothouse of type of 6d, their bearing strength, and buildings can not be provided in general
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Description
A method is considered, on the concrete example of hothouses of type of 6D, for calculation of bearing strength of overhead and lower belts of farms of coverage. The vital necessity of deep analysis of the question of bearing strength appeared in the light of satisfied mass erection of hothouses constructions of which are bought in the countries of Near East. However, a simple transfer of constructions of hothouses made in the countries of Near East can not be successful on the territory of the Russian Federation. These constructions of hothouses can not be maintained in some conditions, according to service exploitation, like snow loadings, in other cases - wind loadings, and in third case, a construction can collapse without visible reasons. The conducted successive static, dynamic and seismic analysis, executed due to the normative documents and the norms of supplier operating on the territory of the Russian Federation, in attachment to the real sections of bearings structural elements, allowed us expose the stated below percentage of the use of the examined elements of constructions. Lower belt of farms of coverage: on the norms of the Russian Federation, on the first maximum state percent of the use – 395 %; there is a percent of the use on the second maximum state – 999 %; on the norms of the Russian Federation taking into account loadings of supplier, on the first maximum state percent of the use – 339,3 %; there is a percent of the use on the second maximum state – 999 %. Overhead belt of farms of coverage: on the norms of the Russian Federation, on the first maximum state percent of the use – 495,2%; there is a percent of the use on the second maximum state – 361,4 %; on the norms of the Russian Federation taking into account loadings of supplier, on the first maximum state percent of the use – 150,8 %; there is a percent of the use on the second maximum state – 146,2%. Analysis presented allows establishing that at the load of overhead and lower belts of farms of coverage of hothouses, by combinations of loadings characteristic for the place of location of hothouse of type of 6d, their bearing strength, and buildings in general can not be provided
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Description
A thermal physical and mathematical model of laser cladding with TiNi on steel was developed which allows us to monitor the formation of the structure and the properties of the surface layer. A description of the model included assumptions and simplifications; analysis of the energy balance; numerical modeling of thermal processes; evaluation of the temperature distribution; experimental verification of the obtained solutions. The composition of the steel and TiNi alloy was examined as a two-layer material with different thermal characteristics. The energy balance of the system was described with a heat equation in a three-dimensional form. The main channels of the radiation energy costs were taken into account: absorption surface of the product, loss owed to the reflection surface, energy absorbed by the coating which did not come down to the base material. To solve the differential equation of heat conduction we used the Fourier integral method. In assessing the temperature distribution we have reviewed a dimensional problem when exposed to a point source of the Gaussian distribution in a pulsed mode. Computer calculations used MathCAD graphs of temperature changes at different depths of the TiNi layer and the steel substrate. The results obtained allowed us to develop the recommendations for optimizing the technological parameters of laser cladding of TiNi. The simulation of thermal processes significantly reduces the time and resources required to develop the technology, allowing prediction of the quality of the surface layer during the development of the technology and promoting the adoption of efficient technical and technological solutions
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CLASSIFICATION OF INDEPENDENT SOURCES OF ELECTRIC POWER
Description
In the article the description of the basic kinds of sources of the electric power, their merits and de-merits is resulted. Nowadays independent sources of the electric power on static converters are the most universal. In spite of the fact that electronic devices are capable to provide reliable enough electrosupply with consumers of various capacities and character of loading, however their bad fitness to high - dynamic loadings still is. Therefore elec-tromachine converters remain the basic source of the electric power, as the steadiest to overloads. So even in transport independent sources, for which weight-dimensions parameters are most critical, electromachine converters are used. In the article typical circuits of electromachine converters with synchronous and asynchronous generators, their advantages and lacks in relation to static converters are resulted. And as methods of increase of their efficiency, for example work on the part frequency, are resulted. For the sources executed on static converters, use of circuits with an intermediate link of the part frequency is most perspective, which, in its turn, allows to lower weight-dimensions parameters. As a rule, static converters have bad quality of a target voltage, therefore for increase of its quality use various target electric filters. Controlled filters whit electronic elements in their structure have the greatest efficiency
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REQUIREMENTS AND CONSTRUCTIVE DIFFERENCES OF A STATIC CONVERTER
Description
In this article technical requirements to static converters are examined. We can treat as the basic parameters: efficiency and quality of a target voltage. Weight-dimensional parameters, reliability, maintainability are basic operational parameters, as well as target capacity, size of an starting and target voltage belong to key parameters of static converters. As a rule designing of converters is a uniform constructive complex. As at designing, time of an operating time until first failure is taken into account, time of guaranteed work of the separate elements included in the static converter, are determined on the statistical data. Failure of separate elements of parts of converters are possible because of internal (time of guaranteed work) and external (short circuits, overloads) factors. In the article we have offered the ways of reduction of influence of external factors (for example, we used high-speed automatic switches or iterative static converters in which parts of a power circuit were included in parallel). Using universal static converters allows raising some parameters of efficiency simultaneously. In the article we have also considered a scheme of the iterative converter with variable structure which allows (depending on start and target conditions or requirements) forming an output capacity of the required level and quality without constructive change
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