Conference Technology Transfer: fundamental and innovative technical solutions
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IMPROVED JOINTS OF REINFORCED CONCRETE ELEMENTS IN PRECAST-AND-CAST-IN-PLACE CONSTRUCTION BASED ON DESTRUCTION MECHANICS
Get PDFSystematic theoretical and experimental studies of the keyed joints of concrete and reinforced concrete elements have been carried out at PoltNTU over the recent thirty years that made it possible to formulate recommendations for their design and to improve the existing design solutions of joints. The keyed joints have higher bearing capacity. The method for calculating the strength of the joints is proposed. This method is based on the theory of concrete plasticity, the variational method and the principle of virtual velocities. It considers the stage of destruction and takes into account the full set of influence factors. The research takes into account the influence of the following factors on the joints strength: the ratio of the key depth to its height; compression level; the intensity of reinforcement and the nature of the reinforcement location. The keys of a rectangular profile of circular cross section are considered, which are formed in the voids of the slabs at their ends surface when girders concreting. For their reinforcement, a spatial cage in the form of a hollow cylinder is proposed. The results of experimental verification of the quantitative and qualitative influence on the joints strength of these factors are presented. The boundaries of the efficiency of reinforcement intensity, the degree of compression are determined, the optimal ratio of the depth of the key to its height is accepted. The design features of the joints of multi-hollow floor slabs (roofs) with a monolithic girder and between themselves in a precast-cast-in-place frame structural system, with wall panels in large-panel houses, as well as joints of wall panels on flexible loops in large-panel buildings, are taken into account. Examples of improved structural solutions for connecting elements of modern load-bearing systems based on the specifics of their work are given
DEVELOPMENT OF A WEB SERVICE FOR FORMING A SEMANTIC KERNEL OF A WEBSITE BASED ON DATA MINING METHODS
Get PDFA technique has been developed for the formation of the semantic core of a site for Internet resources with already generated or dynamically generated content. A mathematical model based on data mining methods is given. For analysis and further research, an information technology is developed – a web service. The main users of this web service will be SEO specialists, for whom it will become a convenient tool. This web service relies on data mining methods and statistics on the use of search queries obtained from the Google Search interface. Integration of the data allows to qualitatively select the necessary keywords and give a list of the most optimal, relating to the subject of the site.
For research, the site of the Department of Computer Science of the Azov State Technical University was selected. During the experiment, a list of keywords and phrases was obtained. The words in the list are sorted in decreasing order of performance. The automated formation of the semantic core eliminated the subjectivity of the SEO specialist when selecting words and phrases, the time spent on its formation is ten times less than the manual semantic analysis. The result set included only those words and phrases that are often used in the content and are most significant. Using Google Search to adjust the list of words allows to match words with search queries and select those for which users are looking for information. The web service has a flexible mechanism for regulating (limiting) the number of keywords in the result set.
The main advantage of using this service is that only those words and phrases fall into the semantic core, in response to which there is something to offer visitors on the site
NEW METAL-CONTAINING POLY(URETHANE-SEMICARBAZIDES) ON THE BASIS OF PYRIDINE DERIVATIVES
Get PDFThe growth of science and technology of polyurethanes leads to the development of new materials with more desirable properties. Modification of polyurethane (PU) by incorporating metal and functional groups are used extensively to improve various properties, such as enhanced thermal stability, fire retardancy, flexibility and solubility. In this investigation, a new metal-containing poly(urethane-semicarbazides) bearing a pyridine moiety have been synthesized and characterized by Fourier transform infrared spectroscopy (FTIR), differential thermal analysis (DTA/TG) and tensile strength measurements. The results showed that the incorporation of metal ions into the polymer chain greatly influenced their mechanical and thermal properties. The tensile strength measurements on the PU films showed a marked difference in the elongation and tensile strength for compositions with various metal salts. The nature of the anion of the salt also affects the properties of the polymers, since the anions are able to form complexes with hydrogen atoms of urethane-semicarbazide PU segments. According to the results of DTA, introduction of metal ions leads to the increase of the thermal stability of metal-containing PU, as compared to the original PU. FTIR spectra data confirmed that the metal ions Cu2+, Co2+ are coordinated in the polymer metal chelates with hydrazide and urethane groups. The research results can be used to develop the new materials and methods for the preparation and designing of metal-containing polymers required in various areas, such as development of medical equipment, functional films and other related areas
SURFACE ROUGHNESS OF PARTS MADE TITANIUM ALLOYS MACHINED WITH FACE MILL OF ORIGINAL CONSTRUCTION
Get PDFImportance of the use of titanic alloys is shown in many industries of engineer. Problems which arise at their processing are described that negatively affect process productivity and indicators of surface quality and etc. This is especially important when machining plane surfaces of parts by face milling. The surface roughness depends first of all on geometrical parameters and the shape of the cutting edge of the tool insert that contacts the processed surface. Therefore it was developed an original design of face mill with a stepped insert arrangement with a cylindrical front surface, and at the same time process productivity was improved.
Expediency of use of the proposed design of a face mill it is proved by comparative experimental studies of influence of a form of a front surface of round inserts on roughness of the machined surface of parts from titanium alloy VT1-0. The comparison was made between the machining of the face mill with a cylindrical front insert surface and a standard face mill with round inserts (ISO 6462:2011). A non-composite second-order plan was received results of the study were obtained for the conditions of machining titanium alloy.
The profile of the machined surface was investigated to evaluate the roughness Ra and it was determined that, with the maximum cutting modes, the face mill of the original design provided a lower roughness of the machined surface than a standard mill. The optimum cutting modes are determined by the criterion of the roughness of the machined surface of parts made of titanium alloy VT1-0 and the process productivity of face milling. The proposed face mill provides a 1.26 time increase in productivity compared to machining a standard face mill while obtaining minimal roughness
EXPERIMENTAL STUDY OF THE TECHNIQUE OF CREATION OF REFERENCE FIRE-FIGHTING LINES BY EXPLOSION OF SHELLS WITH A COMBUSTIBLE MIXTURE
Get PDFAbout 40 thousand fires occur in Ukraine in natural ecosystems every year. Fires cause enormous damage to the environment, the population, and also the country's entire economy. Prevention and suppression of fires is one of the most relevant and most important tasks in Ukraine. To combat fires in natural ecosystems, such methods of fighting fires as the creation of reference fire-fighting lines are widely used. The results of an experiment on the creation of fire-fighting lines using an explosion of a single and double shell with a combustible mixture were carried out. To fill the shell, a stoichiometric mixture of acetylene with atmospheric pressure air was used. The shell was a plastic film 150 μm thick. During the experiment, the influence of the size (radius) of the shell and the number of lines on the width of the created reference fire-fighting lines, the distribution of the mass of vegetation along the shell with a combustible mixture before and after the explosion was studied.
The obtained results of the experiment showed that the vegetation removal degree along the charge axis to the vegetation cover after the explosion is 0.05. The dependences of the vegetation removal degree on the reduced energy per one meter of the line with a combustible mixture are obtained. It is calculated that in the experiment, the energy per linear meter of the line with the combustible mixture was 3.04 MJ/m, 6.6 MJ/m and 10.9 MJ/m for the line with a radius of 0.5 m, 0.65 m and 0.9 m, respectively.
The distribution of the vegetation removal degree was experimentally established, and based on the processing of the results obtained, dependencies were determined that made it possible to calculate the width of the reference fire-fighting line
Mathematical modelling of the reaction of condensation telomerization and the investigation of the model
Get PDFA mathematical model of the distribution of mixture components in the equilibrium condensation telomerization is developed depending on the ratio of the amounts of monomers and telogen, as well as the number of HX as regulating parameters, the computer implementation of the model is carried out, and its study is carried out by numerical simulation. The model is based on the well-known schematic diagram of the flow of the condensation telomerization process under the assumption of equal reactivity of the same functional groups (Flory principle). Based on the analysis of the flow pattern of the process, 6 structural elements are identified, reproducible at each stage associated with an increase in the degree of polymerization based on 4 basic components. It is proved that the equilibrium concentrations of these elements, depending on the polymerization degree, depend on the equilibrium concentration of products with a degree of polymerization 1 and are described by infinite geometric progression with the same denominator. According to the physical content of the task, this progression must be convergent. Equations of material balance of components are contained in the form of a system with 4 equations containing infinite sums. It is possible to minimize these sums using the properties of geometric progressions and to obtain a closed system with 4 nonlinear equations for the equilibrium concentrations of the base components.
The Monte Carlo method is used to study the features of the numerical solution of the system of equations of the model. It is found that with a random choice of initial approximations of solutions from an admissible region, the system contains 4 roots, of which 2 contain positive and negative components and are false, and 2 have completely positive components. A valid criterion for finding a real root has a physical meaning based on the calculation of the denominator of a geometric progression. The possibilities of practical use of the model are discusse
Investigation of computer-oriented technologies for the optimization of electric supply and energy saving of railway transport
Get PDFThe analysis of the current state of power electric equipment of traction substations of railways, power supply systems for traction and control systems based on what was shown that current trends to ensure a high level of efficiency of the power industry are directly related to its informatization and the development of distributed computer systems and networks intellectual technology for monitoring, identifying and intellectualizing the management of energy saving modes of electric supply systems. The temporary decomposition of the tasks of management of electric networks of railways and the methodology of the organization of intelligent electric power traction networks are proposed. The methods for registering primary information monitoring parameters of normal and emergency modes of electric networks based on the use of mathematical tools of differential transformations and the presentation of data in the form of T-spectra are developed. On the basis of the system-wide principle of a single information space and the results of experimental studies, the architecture of the computer environment is studied, which reflects the range of possibilities for intellectualizing the traction network based on the characteristics of electricity supply to railways, taking into account restrictions and specificity of consumption. And at its base, modern computer-intelligent technologies have been created for managing energy saving in the process of power supply to railways at the level of traction substations, power supply distances and the upper level of the railway as a whole. The possibilities of the proposed structure of the intellectual traction electric network of Ukrzaliznytsia developed as a result of the mutual integration of the topology of the traction network of power supply and architecture of the computer environment, which is the infrastructure for managing power supply for railway transport, as well as the possibility of integrating real-time monitoring, state, optimization of consumption and management of energy saving in the process during the maintenance of electricity for traction at all levels of management of the railway in market condition
Environmental features and resistance to the anthropogenic load of coniferous introducents in the central part of Ukraine
Get PDFThe current state of coniferous introduced plants growing on the territory of Uman, Cherkasy region is analyzed. Such representatives are the multi-age trees Pinus nigra and Thuja plicata. The studies were aimed at determining their resistance to arid environmental conditions in summer and to adverse factors in the winter period with generally accepted methods. Studies were conducted during 2015-2017. P.nigra trees during the study period received high drought tolerance scores. In Th. plicata plants observed a partial loss of needles turgor during daylight hours. When evaluating the frost resistance, P. nigra trees of different ages did not have visible damage. Young plants Th. plicata were somewhat more vulnerable to the effects of low temperatures, while no damage was found in mature trees.
In general, both species have rather high rates of winter hardiness and drought resistance. This indicates their acclimatization to the given growing conditions. Also, the studied plants tolerate the adverse conditions of the city: dust, smoke, soil compaction. Therefore, it is advisable to use them for landscaping urban areas and personal plots. A feature of these species is that they retain a high decorative effect throughout the year and are good components for creating landscape compositions.
Comparing the conditions of the natural distribution range to the conditions of the cultural areas of the studied species, it is possible to state their successful cultivation, which indicates a high ecological plasticity and significant potential of these plant
Development of the luenberger observer for the automated electric drive of hermetic compressor
Get PDFThe basic requirements for control systems of automated electric drives of hermetic compressors of small refrigeration units are determined. The analysis of the existing sensorless control systems of three-phase AC drives is carried out. The topology of the adaptive Luenberger observer is proposed, which allows real-time evaluation of the current value of the rotational speed and torque on the shaft of the hermetic compressor motor. Based on the linearized model of a three-phase asynchronous motor, the Luenberger observer is synthesized by the modal method with the distribution of the roots of the characteristic polynomial in the standard linear Bessel form. Expressions are obtained for calculating the coefficients of the Luenberger matrix and the geometric mean root of the characteristic polynomial of the observer. To ensure the necessary accuracy of identifying the coordinates of the state of an automated electric drive of a hermetic compressor, an observer structure is proposed based on a complete mathematical model of a three-phase asynchronous motor made in a fixed coordinate system. Using simulation tools, the work of the designed Luenberger observer is studied on the example of a modernized three-phase asynchronous motor of a hermetic compressor of a domestic refrigerator. For this example, the coefficients of the Luenberger matrix and the geometric mean root of the characteristic polynomial of the observer are calculated. The effectiveness of the proposed method for identifying the rotational speed and moment of resistance of a compressor electric motor by an adaptive observer based on the calculation of the electromagnetic torque of the motor from measured sensors of phase voltages and currents is confirmed. The error of the observer under investigation does not exceed 0.5 % in rotation frequency and 10 % in respect to the moment of resistance. The resulting structure of the adaptive Luenberger observer allows to build closed-loop control systems for automated electric drives of the hermetic compressor of a small refrigeration unit
Calculation of safe speed and minimally admissible distance of closing of ships during radar information usage
Get PDFExceeding the safe speed and the minimum allowable distance when ships approach each other is considered as one of the main reasons for their collision, especially when using radar information when sailing in reduced visibility or in confined areas. When assigning a safe speed, among other factors, the rules recommend to take into account the state of visibility of the maneuverable capabilities of the ship, especially the distance required to completely stop the ship, as well as the characteristics, efficiency and limitations of radar equipment. But, besides the quality recommendations in the COLREGs, there are no quantitative estimates of the safe speed and excessive convergence of the ships. Each navigator subjectively assigns a safe speed and determines the minimum allowable approach distance for ships. Therefore, the development of a universal method for calculating safe speed and the minimum allowable distance when using radar information is relevant, and the method itself is effective when used on ships, especially when sailing in difficult navigation areas and with limited visibility. The developed method allows to automate the choice of safe speed and eliminate the subjective factor when it is appointed navigato