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  • 1
    In: Nuclear Energy and Technology, Pensoft Publishers, Vol. 7, No. 4 ( 2021-12-17), p. 333-339
    Kurzfassung: An economic and analytical model for evaluating the criteria of efficiency (profitability) of investments in the projects of innovative nuclear icebreakers of the Northern Sea Route is suggested. The model is based on the new analytical representation of the methodology for forecasting the investment project efficiency that is widely used in international practice. The mathematical expression for the net discounted income provides convenient formulas for calculating several investment efficiency criteria for nuclear icebreakers: internal rate of return, minimum annual revenues from icebreaker convoys, discounted payback period, and the volume of delivered cargo. The paper gives estimates of the criteria for the efficiency of investments in “ Leader ” class icebreakers that depend on the discount rate of cash flows, capital, and operating costs. It is shown that at high capital costs, typical for construction of “ Leader ” class nuclear icebreakers, the minimum required revenue of an icebreaker, representing a financial burden for ships transporting cargo along the NSR, rapidly increases with the growth of discount rate and the reduction of investment payback period. This means that the profitability of such icebreakers is only possible at low discount rates of 2–3% per year, which is an extremely low-interest credit. Even with low interest and impressive technical characteristics of the icebreaker (high speed of navigation, large number of ships in the caravan and their maximum capacity) the payback period would exceed 25 years.
    Materialart: Online-Ressource
    ISSN: 2452-3038
    Sprache: Unbekannt
    Verlag: Pensoft Publishers
    Publikationsdatum: 2021
    ZDB Id: 2858592-6
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    In: Technical Sciences and Technologies, Chernihiv Polytechnic National University, , No. 1(31) ( 2023), p. 36-45
    Kurzfassung: Milling technological operations are one of the most productive and widespread methods of metalworking. From the point of view of providing the blank with the desired configuration, thesetechnological operations represent the most universal method of processing. Technological operations of plunger milling are now becoming more and more widespread. Plunger milling is used precisely when the use of traditional methods is impossible due to excessive vibrations. Performing technological operations of plunger milling is fundamentally different from performing technological operations of traditional milling. The article contains recommendations that must be followed when performing technologicaloperations of plunger milling. The purpose of the article is to determine the possibility of using any CAM-system to ensure high-quality execution of technological operations of plunger milling. To do this, it is proposed to check whether the CAM-system supports two requirements. The article provides a list of the most common CAM-systems, indicating whether a given software module supports plunger milling. The article proposes a scheme for the implementation of the trajectory of the plunger cutter for the use of any CAM-system in order to ensure the high-quality execution of technological operations of plunger milling. This proposed scheme consists of four main stages. The first stage of the proposed scheme consists of the formation of an array ofholes within the contour of the cavity or other surface being processed. The essence of the second stage of the proposed scheme is to determine the value of the allowance for finishing (depending on the complexity of placing the holes in the contour of the cavity, it is possible to increase the allowance for processing). The third stage of the proposed scheme consists in developing, based on the array of holes that was formed in the first stage, the software code for inserting a cutter into each of the holes in accordance with the coordinates that are specified (by analogy with the development of drilling cycles). The essence of the fourth stage of the proposed scheme is to manually program the removal of the plunger cutter from the walls of the cavity or other surface being processed
    Materialart: Online-Ressource
    ISSN: 2411-5363 , 2519-4569
    Originaltitel: ТЕХНОЛОГІЧНІ ОСОБЛИВОСТІ ВИКОНАННЯ ОПЕРАЦІЙ ПЛУНЖЕРНОГО ФРЕЗЕРУВАННЯ
    URL: Issue
    Sprache: Unbekannt
    Verlag: Chernihiv Polytechnic National University
    Publikationsdatum: 2023
    ZDB Id: 2913922-3
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    In: Technical Sciences and Technologies, Chernihiv Polytechnic National University, , No. 4(30) ( 2022), p. 50-57
    Kurzfassung: The article is devoted to questions on possibility and expediency of work on working of products on DFM irrespective of works on working of products on other properties of quality. Depending on the properties, there are the following quality indicators: purpose indicators, reliability indicators, ergonomic indicators, aesthetic indicators, safety indicators, ecological indicators, manufacturability indicators, transportability indicators, standardization and unification indicators, patent lawindicators, economic indicators. The economy of countries where a lot of attention is paid to quality (both on the part of the producer and on the part of the consumer), have achieved great success in the development and provision of a high standard of living for their citizens. DFM as property of a product is a part of its quality and is one ofproperties of quality of products, and product working on DFM is an integral part of works on maintenance of quality of products. DFM is characterized by a number of indicators. DFM indicators form one of the types of product quality indicators along withindicators of purpose, reliability, level of standardization and unification, etc. The need for this research arises due to the fact that different specialists conduct the testing of products according to the main quality properties. So, for example, testing and evaluation of products according to reliability indicators is carried out by specialists in the field of reliability theory, engineers-designers are involved to test the ergonomic properties of products, testing of products for manufacturability should be carried out by technologists, etc. For the decision of the given problem it is offered to use methods of the theory of potential efficiency of complicated systems. The theory of complicated systems supposes that at designing of products it is supposed to conduct working of products on DFM and other separate properties or quality indicators, however working of designs of products on DFM and other separate indicators of quality is less effective, than simultaneous working on all indicators of quality.
    Materialart: Online-Ressource
    ISSN: 2411-5363 , 2519-4569
    Originaltitel: ТЕХНОЛОГІЧНІСТЬ –НЕВІД’ЄМНА СКЛАДОВА ЯКОСТІ ВИРОБУ
    URL: Issue
    Sprache: Unbekannt
    Verlag: Chernihiv Polytechnic National University
    Publikationsdatum: 2022
    ZDB Id: 2913922-3
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
    Online-Ressource
    Online-Ressource
    Chernihiv Polytechnic National University ; 2022
    In:  Technical Sciences and Technologies , No. 4(30) ( 2022), p. 40-49
    In: Technical Sciences and Technologies, Chernihiv Polytechnic National University, , No. 4(30) ( 2022), p. 40-49
    Kurzfassung: Now methodological aspect of choosing machine tools is still not worked out, we can clearly conclude that it is a very urgent task that needs a special attention and responsibility. The purpose of the article is to create methodological foundations for a more justified choice of models of metal cutting machines when designing technological processes of manufacturing parts. It is proved in the article that the geometry of surfaces is the dominant feature of the items in the solution of the problem of choosing a particular model of machine tool, which can provide a process forthe manufacture of the part.
    Materialart: Online-Ressource
    ISSN: 2411-5363 , 2519-4569
    Originaltitel: GEOMETRIC ASPECT OF CHOOSING MODELS OF BASIC TECHNOLOGICAL EQUIPMENT
    URL: Issue
    Sprache: Unbekannt
    Verlag: Chernihiv Polytechnic National University
    Publikationsdatum: 2022
    ZDB Id: 2913922-3
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 5
    In: Koloproktologia, Russian Association of Coloproctology, Vol. 22, No. 3 ( 2023-09-21), p. 10-49
    Kurzfassung: .
    Materialart: Online-Ressource
    ISSN: 2686-7303 , 2073-7556
    Sprache: Unbekannt
    Verlag: Russian Association of Coloproctology
    Publikationsdatum: 2023
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 6
    Online-Ressource
    Online-Ressource
    Chernihiv Polytechnic National University ; 2022
    In:  Technical Sciences and Technologies , No. 1(27) ( 2022), p. 60-66
    In: Technical Sciences and Technologies, Chernihiv Polytechnic National University, , No. 1(27) ( 2022), p. 60-66
    Kurzfassung: The effect of stress concentration on fatigue behavior of steel 20 is studied. Experimental study is carried out on tubular smooth and notched specimens under uniaxial cyclic loading and alternating torsion. Load and strain controlled fatigue tests were carried out at room temperature using servohydraulic machine with independent control of push-pull and torsion loads with frequency of 0.5-3 Hz. One basic geometry for two different types of specimens shown in Figure 1 with 1.1 mm wall thickness, 22 mm inside diameter, and 40 mm gauge length was used in this work. One type was a tubular smooth thin-walled specimens, the other type was the same thin-walled specimen with 3.4 mm circular through-thickness hole at the middle of gauge length. The 5% load drop for uniaxial strain control tests and 5% strain and rotation angle increment for uniaxial and torsion load control tests respectively, as compared to midlife stable cycle for smooth specimens were considered as a small crack initiation life. The criterion of maximum principal stress was used as a control parameter of the test program. Torque loading was accompanied by a significant decrease in durability compared to uniaxial loading due to conservative methodology. Although maximum principal stress criterion could correlate axial and torsion constant amplitude data of notched specimens with a factor of 4, it could not correlate axial with torsion data of smooth specimens. It is found that the prediction of fatigue life can be successfully performed according to the shear form of Fatemi-Soci criterion by taking into account the mechanism of destruction of samples. The shear strain-life curve was generated based on von Mises criterion. The FS parameter was associated with local stress-strain condition based on FE analysis results.
    Materialart: Online-Ressource
    ISSN: 2411-5363 , 2519-4569
    Originaltitel: ВПЛИВ КОНЦЕНТРАЦІЇ НАПРУЖЕНЬ НА ДЕФОРМУВАННЯ СТАЛІ 20 ПРИ ЦИКЛІЧНИХ НАВАНТАЖЕННЯХ
    URL: Issue
    Sprache: Unbekannt
    Verlag: Chernihiv Polytechnic National University
    Publikationsdatum: 2022
    ZDB Id: 2913922-3
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 7
    In: Technical Sciences and Technologies, Chernihiv Polytechnic National University, , No. 4(30) ( 2022), p. 14-23
    Kurzfassung: The main problem of manufacturing products in conditions of flexible automated production is the achievement of high quality indicators of parts, such as accuracy characteristics, surface roughness and surface layer condition. Obtaining of high quality parts in modern technological systems requires the study of specific features of flexible production. Frequent readjustment of equipment, replacement of tools, redistribution of characteristics of the elastic system of machine tools, the production of parts from materials of different workability determine the variablenature of the accuracy parameters of products manufactured in flexible manufacturing systems (FMS). In addition, the difficulties associated with the full automation of the technological process are added: automatic basing and fixing of workpieces and tools, transfer and reorientation of parts for processing on various machine modules, accumulation of errors when basing blanks on satellites, branching of dimensional connections of multipurpose machines, inaccuracies of automatic adjustment and positioning of the tool, the need for active control of the treated surface and the condition of the cutting tools, providing feedback between real and specified accuracy, automatic maintenance of thermal characteristics of machine equipment, ensuring optimal cuttingmodes for all FMS machines. The solution of most of these problems is achieved through adaptive management of the processes in order to obtainspecified indicators of processing quality. Designing the optimal technological process under changing conditions of flexible production is a very difficult task, due to the multivariate technology of processing parts included in the group. Meanwhile,in the theory of group production there are methods to optimize the process of choosing the right technological solution. With the optimization of group technologies, it is necessary to be able to specialize in real production. On the first stage on the basis of advanced technological processes, it is necessary to create a type for the development of technological processes. The cost of developing such processes is insignificant, so that the technology is widely implemented. In the process of developing group technological processes of machining complex parts or a complex combination of surface elements of a part in order to ensure the efficiency of the process, it is necessary to solve the problem of optimizing machining parameters in accordance with accepted optimality criteria and taking into account the main technical limitations. At the same time, it is considered as the optimization of constantly set, for a specific instrumental group adjustment, processing modes using the methods of mathematical modeling and automated information processing, and continuous optimization with the help of control systems for technological equipment, which are part of the FMS. Therefore, the problem of calculating and optimizing cutting modes on interconnected FMS machines is extremely urgent. At the same time, not the most intense modes are considered optimal, but just those that ensure the stable operation of the FMS for a long time.
    Materialart: Online-Ressource
    ISSN: 2411-5363 , 2519-4569
    Originaltitel: ОПТИМІЗАЦІЯ РЕЖИМІВ РІЗАННЯ НА ВЕРСТАТАХ ГНУЧКИХ ВИРОБНИЧИХ СИСТЕМ
    URL: Issue
    Sprache: Unbekannt
    Verlag: Chernihiv Polytechnic National University
    Publikationsdatum: 2022
    ZDB Id: 2913922-3
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 8
    Online-Ressource
    Online-Ressource
    Kremenchuk Mykhailo Ostohradskyi National University ; 2018
    In:  Up-to-date resource- and energy- saving technologies in mining industry ( 2018-06-30), p. 29-37
    In: Up-to-date resource- and energy- saving technologies in mining industry, Kremenchuk Mykhailo Ostohradskyi National University, ( 2018-06-30), p. 29-37
    Materialart: Online-Ressource
    ISSN: 2074-1537
    Sprache: Unbekannt
    Verlag: Kremenchuk Mykhailo Ostohradskyi National University
    Publikationsdatum: 2018
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 9
    In: Micromachines, MDPI AG, Vol. 13, No. 11 ( 2022-11-21), p. 2033-
    Kurzfassung: Triethylaluminum Al(C2H5)3, TEA, and triethylborane, B(C2H5)3, TEB, are transparent, colorless, pyrophoric liquids with boiling points of approximately 190 °C and 95 °C, respectively. Upon contact with ambient air, TEA, TEB, as well as their mixtures and solutions, in hydrocarbon solvents, ignite. They can also violently react with water. TEA and TEB can be used as hypergolic rocket propellants and incendiary compositions. In this manuscript, a novel scheme of the heterogeneous interaction of gaseous oxygen with liquid TEA/TEB microdroplets accompanied by the release of light hydrocarbon radicals into the gas phase is used for calculating the self-ignition of a spatially homogeneous mixture of fuel microdroplets in ambient air at normal pressure and temperature (NPT) conditions. In the primary initiation step, TEA and TEB react with oxygen, producing an ethyl radical, which can initiate an autoxidation chain. The ignition delay is shown to decrease with the decrease in the droplet size. Preliminary experiments on the self-ignition of pulsed and continuous TEA–TEB sprays in ambient air at NPT conditions are used for estimating the Arrhenius parameters of the rate-limiting reaction. Experiments confirm that the self-ignition delay of TEA–TEB sprays decreases with the injection pressure and provide the data for estimating the activation energy of the rate-limiting reaction, which appears to be close to 2 kcal/mol.
    Materialart: Online-Ressource
    ISSN: 2072-666X
    Sprache: Englisch
    Verlag: MDPI AG
    Publikationsdatum: 2022
    ZDB Id: 2620864-7
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 10
    In: Fuels, MDPI AG, Vol. 3, No. 3 ( 2022-06-24), p. 375-391
    Kurzfassung: The pulsed detonation (PD) gun technology was applied for the autothermal high-temperature conversion of natural gas and atmospheric-pressure oxygen-free allothermal gasification of liquid/solid organic wastes by detonation-born ultra-superheated steam (USS) using two flow reactors of essentially different volume: 100 and 40 dm3. Liquid and solid wastes were waste machine oil and wood sawdust, with moisture ranging from 10 to 30%wt. It was expected that decrease in the reactor volume from 100 to 40 dm3, other conditions being equal, on the one hand, should not affect natural gas conversion but, on the other hand, could lead to an increase in the gasification temperature in the flow reactor and, correspondingly, to an increase in the product syngas (H2 + CO) quality. The PD gun was fed by natural gas–oxygen mixture and operated at a frequency of 1 Hz. As was expected, complete conversion of natural gas to product syngas in the PD gun was obtained with H2/CO and CO2/CO ratios equal to 1.25 and 0.25, irrespective of the reactor volume. Liquid and solid wastes were gasified to H2, CO, and CH4 in the flow reactors. The steady-state H2/CO and CO2/CO ratios in the syngas produced from waste machine oil were 0.8 and 0.5 for the 100-dm3 reactor and 0.9 and 0.2 for the 40-dm3 reactor, respectively, thus indicating the expected improvement in syngas quality. Moreover, the maximum mass flow rate of feedstock in the 40-dm3 reactor was increased by a factor of over 4 as compared to the 100-dm3 reactor. The steady-state H2/CO and CO2/CO ratios in the syngas produced from the fixed weight (2 kg) batch of wood sawdust were 0.5 and 0.8 for both reactors, and the gasification time in both reactors was about 5–7 min. The measured H2 vs. CO2 and CO vs. CO2 dependences for the syngas produced by the autothermal high-temperature conversion of natural gas and atmospheric-pressure allothermal gasification of liquid/solid organic wastes by USS at f = 1 Hz were shown to be almost independent of the feedstock and reactor volume due to high values of local instantaneous gasification temperature.
    Materialart: Online-Ressource
    ISSN: 2673-3994
    Sprache: Englisch
    Verlag: MDPI AG
    Publikationsdatum: 2022
    ZDB Id: 3040987-1
    Standort Signatur Einschränkungen Verfügbarkeit
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